1. From forest to market

Paperboard the natural choice 9

The philosophy of choice 15

The paperboard product 17

Choices of raw material 19

Differences paper and paperboard 22

Fibre to board 26

The paperboard machine 36

Extrusion coating and lamination 38

Board lamination 44

Design and carton construction 46

Consumer use and appeal 56

Distribution and storage 57

Retailing 60

Taint and odour neutrality 61

Migration into foodstuffs 65

IGGESUND PAPERBOARD | Reference Manual 7 Paperboard – the natural choice

8 Reference Manual | IGGESUND PAPERBOARD Paperboard – the natural choice

Paperboard – the natural choice

When Iggesund published the Paperboard Reference how these paperboards behave in graphic post-produc- Manual in 1992 it was an attempt to create a reference tion or in packaging lines, the conclusion is even more manual for everyone who works professionally with paper- clear: the key issue is not price per kilo, it is performance. board material. Over the years the book has been much When purchasing the input material, it is important to as- appreciated, and in addition to its purely professional use sess the cost per useable end product instead of merely within the graphics and packaging industries, the book considering the price per kilo. also features in courses given by a number of universities and other third-level educational institutions. Our ambition Experiencing paperboard has been to maintain a high level of factuality and neutrality European paperboard normally has a multi-layer structure of information so that the Paperboard Reference Manual that creates a stiffness which exceeds that of all single- will remain a credible work of reference. layer, cellulose fi bre-based materials. This stiffness is part In this, the second, revised edition, we have continued of the quality that we offer our customers and that can be with this tradition, with one exception. In this introduction exploited to reinforce the quality experience or reduce the you are now reading, we discuss some aspects of paper- grammage of the input material. board which are not so easy to quantify or assess. Another parameter which is often used when choosing a material is the degree of measured whiteness. Whiteness Paperboard – a natural material as measured on the paper and board market is a simple As a material, paperboard is special. It is the material with number which is a combination of three different measured the highest added value within the material system com- values. The equation by which these values are assessed prised of paper and paperboard, and is most often used is such that paperboards which look completely different for packaging and high-quality printed materials. can have the same whiteness value. What is most absurd This material system includes everything from virgin is that the blue shade, which causes major problems when fi bre-based paperboards, such as Invercote and Incada, printing accurate skin tones, is rewarded in this combined to paper products made of fi bres that have been repeat- calculation of whiteness. At Iggesund, we have deliber- edly recycled. In the market for paper-based products, ately chosen not to attain the highest whiteness measure- pricing is typically based more on price per unit of weight ment. We do not want our paperboard to become bluer in than price in relation to the end result in terms of its func- a purely optical sense, which would make it harder for our tions, visual appearance and economy of production. customers to accurately reproduce skin tones. We would In a typical advertising or packaging project, great effort have no problem becoming even whiter if we wanted to, is taken to fi nd the right designer and photographer, and but we have chosen a whiteness level for good colour to handle all the produced material in the optimal way reproduction. throughout the production chain. As manufacturers of high-quality paperboard, we are sometimes astonished Paperboard within the goods fl ow at how casually many producers of packaging and printed Paperboard is one of the most widely used packaging materials choose their input material, after having taken materials in the world thanks to the economic benefi ts it considerable care over the quality of the entire process offers throughout the chain from producers to consumers. that precedes printing or converting. It is easy to fi nd ex- Carton blanks can be transported fl at and cost effectively pensive catalogues or cartons whose colour-printed areas until they are erected and fi lled with the contents they are have cracked along the crease even before any consumer designed to protect and preserve throughout the dis- or reader has handled them. There are also countless tribution chain to the consumer. The printing properties brochures, whose cover, if it had been made of stiff pa- of paperboard packaging make it easy to convey both perboard instead of thick fi ne paper, would have had far commercial messages that encourage purchase and greater impact on the recipient’s experience of quality. legally required information about the contents. Paper- Virgin fi bre-based paperboard is the paper-based mate- board packaging can also be recycled as a material or its rial with the greatest added value, and for many applica- stored biogenic energy can be recovered via combustion tions there are simpler and more cost-effective solutions. or anaerobic digestion in accordance with the appropriate However, for anyone who wants the possibility of creating environmental targets. Paperboard is also compostable, more complex shapes to attract attention, for anyone which means that as a material it functions in all the waste who wants taint- and odour neutrality, or for anyone who streams listed in the European directive on packaging and is looking for the ultimate in printing properties, our virgin packaging waste (EC94/62). fi bre-based paperboards, Invercote and Incada, are inter- esting options. If the potential purchaser then explores

IGGESUND PAPERBOARD | Reference Manual 9 Paperboard – the natural choice

For a better environment Compared to other materials, paperboard made of virgin At Iggesund, paperboard production goes hand in hand fi bres has high performance and relatively low weight. It with sustainable forest management. For every tree which is safe for consumers to use because it contains known is harvested and used in our production process, we plant substances and is made in the same way every time. three or four new ones. The result is a sustainable closed- In most cases paperboard packaging remains folded or loop cycle that stretches over a century or more. Those of fl at until the products are packed. Thanks to paperboard’s us who are now collecting the pine cones containing the small volume and low weight, large amounts of energy are seeds for these new trees will not be alive when Iggesund saved in the transport chain. Paperboard cartons can be harvests the trees that will be the fruits of our labour. dimensioned to maximise the use of loading pallets, which Our operations at both Iggesund and Workington are leads to further signifi cant energy savings in the distribu- energy effi cient and their environmental performance fi g- tion chain. When paperboard cartons have served their ures are well within the limits prescribed by their permits. purpose they can be folded and compressed before being One of our long-term goals is to further minimise the im- transported to a suitable recycling station. At every step pact of our large-scale industry on the local environment. of the way, paperboard packaging saves more energy and At the most fundamental level, we live off what nature has lower environmental impact than most other packag- gives us. A business that bases its operations on this fact ing solutions. – and has done so for more than four centuries – must Paperboard is made from timber, which is a renewable have a sustainable and long-term approach. resource. Sunlight and water make the trees grow, while We produce one of industrial society’s most environ- they also bind carbon dioxide and give off the oxygen es- mentally sustainable products. It is made from a renew- sential to life. The forest’s closed ecological loop provides able raw material and can be recycled both as energy and us the raw material for paperboard, while used cartons material. It has minimal impact on our air and water, and and printed matter have their own role to play in the recy- produces no waste material that is sent to landfi ll. cling system of a sustainable society. As a material, paperboard is a good component in any sustainable environmental strategy. An overall view We work within the most sustainable material system in In considering the merits of packaging and graphical ma- existence. We have been responsible stewards of our raw terials, or the impact of their manufacture on the environ- material for centuries. Our manufacturing is integrated ment, it is important to take a holistic view. The issues to – we transform our own timber into pulp that is optimised be considered will normally include four key subjects – the for board production, which gives advantages of produc- use of raw materials and energy; the production process; tion economy, quality and quality consistency. Rising product and function; and final recycling or disposal. energy prices and more stringent environmental demands It is meaningless and misleading to address narrow are increasing paperboard’s relative competitiveness issues within any of these broad headings, and at the versus other material systems. same time ignore considerations arising from the wider, On the horizon are a greater use of biomass, smarter overall view. energy solutions that further improve our economy of production, and new spinoff products that make the forest Meeting real needs raw material even more interesting. Paper and paperboard As one of the longest surviving materials for communica- are a material system whose raw material is renewable, tion and packaging, paperboard has been meeting the whose products are recyclable in many ways, and where requirements of many societies for a long time. there already exist sophisticated systems for on-site recy- Nowadays, discussions about the general topic of cling and energy recovery. packaging often focus on the issue of whether or not Our history goes back many centuries but our material packaging actually serves a useful function. The question still has a long future ahead of it! is often raised in very simplistic terms – is packaging really Paperboard is a natural material with many applica- necessary? tions. As a print medium, paperboard can withstand all the In fact, effective packaging has helped to revolutionise strains and stresses involved in the use of advanced fi nish- the mass distribution of products in advanced industrial so- ing techniques. Paperboard is also highly durable, ensur- cieties. In many cases the existence of effective packaging ing that printed materials will last for a long time. Typical actually saves spillage and waste by protecting and graphical applications are book covers, cards, and CD preserving products en route from the manufacturer to the and DVD covers. Paperboard packaging is a competitive retailer and on to the consumer. method of conveying products from the manufacturer to Packaging meets real needs. Consumers need to have the consumer while also being easy to recycle. In terms of a wide choice of conveniently available, well presented and graphic design, paperboard’s excellent printing properties well packaged products from which to choose. Manufac- give brand owners great freedom to express their brand’s turers and retailers need to effectively impart information individuality and thereby attract the consumer’s attention. and attract purchasers.

10 Reference Manual | IGGESUND PAPERBOARD Paperboard – the natural choice

IGGESUND PAPERBOARD | Reference Manual 11 Paperboard – the natural choice

Raw materials and varnishes also requires careful control to ensure that As we explain in the description of our manufacturing residues do not remain and have an impact on the taste process, the wood fi bre used to produce our products is a and odour of the product. renewable resource. The managed forests which supply the timber are constantly replenished. A vigorously grow- Knowledge material ing forest is effi cient in absorbing carbon dioxide, fi xing The Iggesund Paperboard Reference Manual is part of the carbon, and producing oxygen. Iggesund Anchor Material, a body of information material that also consists of the following publications: Energy • Iggesund Product Catalogue The chemical pulping process is highly energy effi cient and • Paperboard – the Iggesund Way the chemical recovery in the pulping process is also very • Graphics Handbook – Paperboard the Iggesund Way high. The production of pulp and the manufacture of pa- • www.iggesund.com perboard are carried out on the same site in a continuous The Reference Manual is the most extensive and techni- integrated process, giving benefi ts in quality, effi ciency, cal of these texts. It attempts to convey all the collected and economy. knowledge we can present with regard to the design and production of paperboard applications. The Reference Taint and odour Manual is primarily a consultative document intended to The taint and odour characteristics of the packaging itself assist readers who wish to improve their possibilities of are of prime importance where long term close or direct getting the most out of their paperboard material. It places contact must not impair those characteristics of the prod- great emphasis on paperboard properties, since these de- uct it is designed to protect. fi ne and limit the performance it is possible to achieve with The selected packaging must therefore be produced this natural material – whether that performance involves from raw materials which are made from pure materi- effectively conveying a message or effi ciently transporting als, selected and processed under carefully controlled a product through the entire distribution chain. conditions. Following manufacture, the application of inks

12 Reference Manual | IGGESUND PAPERBOARD Paperboard – the natural choice

The objective of the Iggesund Anchor Material is to assist Paperboard – the Iggesund Way people involved in specifying, selecting, printing, convert- Contains basic facts about Invercote and Incada and the ing or using paperboard. Both the experienced paper- paperboard manufacturing process. It also describes the board user as well as the less frequent user should fi nd the customer benefi ts available from Iggesund Paperboard’s information they require within this information package. mills and paperboard manufacturing processes, customer support and service. The Iggesund Paperboard Reference Manual contains the following information The Graphics Handbook • basic facts about paperboard – Paperboard the Iggesund Way • paperboard appearance and performance properties, Focuses primarily on graphical production and fi nishing, and their interdependencies and only touches on the topics of packaging design and • paperboard conversion methods and the possibilities/ materials knowledge. Selected parts and digital versions requirements they place on paperboard properties. of the publications are available on www.iggesund.com. If you require further help, please contact your local The Product Catalogue provides Iggesund Paperboard representative. • facts and fi gures about paperboard properties The information in the Iggesund Anchor Material is • general technical information about paperboard correct at publication. It is subject to review as part of handling, quality assurance, product safety regulations, Iggesund Paperboard’s commitment to continuing prod- sustainability and paperboard terminology. uct development.

IGGESUND PAPERBOARD | Reference Manual 13 Paperboard – the natural choice

14 Reference Manual | IGGESUND PAPERBOARD The philosophy of choice

The philosophy of choice

The paperboard choice is determined by the end use Packages with creative shapes attract attention. An exist- application. We recommend, as the fi rst priority, that the ing product might be given a new package to increase end use needs are analysed in terms of appearance and sales. Paperboard as a material provides endless options performance. for constructing creative shapes. Aspects of appearance and performance needs for the two major applications, graphical and packaging prod- Physical protection needs ucts, are described below. The concept of physical protection involves the end user’s requirement that the packages withstand external forces Graphics in order to protect and hold its contents under various Graphical applications can be postcards, brochures, or condi tions. This protection is needed during transport book covers. The purpose is to convey a message and and storage. paperboard is the medium. The medium is always a part To meet extreme requirements, e.g. deep-freeze appli- of the message, so the appearance of the medium must cations, additional functional protection is required. correspond to the message it carries. Protection can also be vital during use. A cigarette pack, Printed texts and graphic images are used to convey for example, must still look attractive after being carried in the message. A metallic, glossy or matt appearance is an a handbag or pocket. effective way of giving the graphical product, such as a magazine cover, an exclusive image. Relief and creative shapes can be used to generate interest. A graphical product that may be handled many times, for example a book cover, requires considerable durability. Transportation costs can be a major part of the total production cost in graphical applications, for example postage costs when mailing brochures to customers.

Packaging The primary task of a package is to protect the contents from the surrounding environment, which might include impacts during handling, pressure in stacking, and extremes of temperature and moisture. In addition to its strength the paperboard package is also very suitable for promotional purposes. During transportation the protection requirement is decisive, but on a shelf in the grocery store the package is more promotional than protective. The major purposes of the package, which can change in emphasis during the products life cycle, are: • Protect the product during transportation and storage. • Promote the product with an attractive appearance. • Inform the consumer about how to use the product. • Protect the product during consumer use. The demands for protection might vary as well as the needs for promotion. Each end use application has its own combination of protection and promotional requirements.

Promotional needs The package promotes the product and creates an im- age of the product for the customer. The product and the package must create the same impression. An exclusive perfume needs a package with a corresponding appear- ance, for example a metallic fi nish. Pharmaceutical prod- ucts often have packages which are very white to empha- sise the image of a clean and effi cacious product.

IGGESUND PAPERBOARD | Reference Manual 15 The philosophy of choice

Possibilities and contradictions duction stops in converting and fi lling, due to low runnabil- Promotional and physical protection needs are met by ity, it will result in a costly package. A wise choice in the the properties of the paperboard, e.g. smoothness, stiff- beginning saves a lot of money in the end. When consid- ness and strength. Whilst it is always possible to fi nd an ering production economy in choosing paperboard it is optimum paperboard solution for packaging and graphi- important to have an overall view. cal needs it is important to realise that properties such as smoothness, stiffness and strength, while they all vary with Consistency density, do so in different ways due to the laws of nature. The importance of consistency cannot be overemphasised. The demand for consistency applies to all paperboard Limitations due to the laws of nature properties, including both appearance and performance Stiffness and strength are two properties which are depend- parameters. ent on the density of the paperboard, but in opposite ways. Two aspects of consistency are relevant: This contradiction is due to the laws of nature and is related • consistency within the order to the characteristics of the cellulose fi bres. The general re- • consistency between orders. lationship between stiffness, strength, surface appearance The cost benefi t of conversion and use without prob- and density is shown in the illustrations. lems and wastage is signifi cant. Short runs with frequent make-ready stops for new jobs put increased demands on Relative economy of production reliability. It is a great advantage if settings from a previous If a product is expensive, the package will be more intri- run can be used again and again, thereby avoiding costly cate and exclusive to match the product. However, the adjustments. cost of the package as a percentage of the value of the When choosing a paperboard it is therefore important product is still very low. to choose a paperboard supplier that has a documented Runnability is a property which is of great importance reliability. The consistency criterion is probably the most when comparing the economy of production of various important paperboard requirement. materials. If the chosen paperboard causes a lot of pro- STIFFNESS STRENGTH SURFACE APPEARANCE SURFACE

DENSITY DENSITY DENSITY

16 Reference Manual | IGGESUND PAPERBOARD The paperboard product

The paperboard product

Since the mid-19th century the primary source of cellu- exceeds the amount of timber that is harvested. lose fi bre has been wood. The fi bre is separated by either This careful forest management ensures that even in the chemical or mechanical means from naturally occurring future the forests will form part of the sustainable cycle of species. In the case of Iggesund these species are mainly nature and be a permanent source of raw materials. spruce, pine and birch from managed forests in Scandina- The fi bres in a tree trunk run parallel to its length. The via and elsewhere in Europe. Such forests are maintained fi bre length varies according to the tree species. The rela- and expanded by the industries that rely on good access tionship is indicated by the table below. to timber. As a result of these efforts the stock of growing trees is increasing every year. In many areas growth now

Spruce fi bre – long and fl at Birch fi bre – short and cylindrical

Pine fi bre – long and fl at Mixed fi bres of spruce, pine and birch

Species Fibre length mm Fibre width μm Shape

Spruce 3.1 – 3.5 19 – 50 Ribbon fl at Pine 2.0 – 3.0 22 – 50 Ribbon fl at Birch 0.9 – 1.2 20 – 35 Cylindrical with pointed ends

IGGESUND PAPERBOARD | Reference Manual 17 The paperboard product

Cellulose and the laws of nature Carbon dioxide and water are converted into simple glucose-based sugars by the action of sunlight on the OXYGEN (O2) CARBON DIOXIDE (CO2) green chlorophyll-containing cells of the plant kingdom. SUNLIGHT This process is known as photosynthesis and is accompa- nied by the emission of oxygen. The natural sugars can be polymerised in plants to produce cellulose. Cellulose has a high molecular weight and a straight- chain molecular structure. Plants use cellulose to grow by constructing cells – what we call fi bres – and other struc- tures which support the life of the plant. Each species has its own characteristic fi brous structure. Many tree species CHLOROPHYLL have been cultivated and developed over time into a renew- SUCROSE, ETC able source of raw materials for the production of a wide range of paper and paperboard products. Careful forest management and the manufacture of paper products are therefore closely linked. Cellulose makes up around 44 % of the wood fi bre. Pure cellulose fi bres are soft, fl exible and white. The other constituents are hemicelluloses, lignin and extractives. Hemicelluloses are a group of substances related to cellu- WATER (H2O) lose but have lower molecular weight and a more compli- cated chain structure. Lignin is a more complex polymer and very different from cellulose. It is hard and brittle. Both hemicelluloses and lignin occur in the fi bre but the main concentration of lignin is between the fi bres, giving adhe- sion and rigidity to the structure of wood. The process of fi bre separation, or pulping, takes ad- vantage of the differences between lignin and cellulose.

More laws of nature There are natural properties which all wood fi bres have to a greater or lesser degree as well as specific properties associated with the fi bres of particular tree species. Fibre characteristics are also infl uenced by the method of pulp- ing which is used.

The general properties • The ability of fi bres to grip each other and bond into a strong, homogeneous structure. • Flexibility, shape and dimensional properties which en- able fi bres to form a uniform interlaced network. • The capacity of the fibres to be favourably modified, mechanically or by using additives, during the production process.

Different levels of magnifi cation of the wood fi bre, revealing the difference between the seasonal growth and a close-up of the fi bre showing its hollow interior and the thin layer of lignin holding the fi bres together

18 Reference Manual | IGGESUND PAPERBOARD Choices of raw material

Choices of raw material

Types of fi bre Chemical Basically the choice is between long fi bres (spruce/pine) This process preserves the length of the virgin fi bre. The and short fi bres (e.g. birch). The board maker carefully se- pure cellulose extracted has a high degree of consolida- lects and blends different fi bres to achieve the appearance tion. Both of these features produce a very strong paper- and functional properties desired for specifi c products. board sheet. The fibre is flexible and soft, giving good creasing, Types of pulp embossing, and die-cutting properties and low dust There are three different pulping processes, which all pro- generation. duce different kinds of pulp: mechanical, chemical, and Bleached cellulose pulp has high whiteness, brightness recycled fi bre. and light stability. Paperboard made of virgin fi bre pulp has the highest possible purity and provides packaged prod- Mechanical ucts with the best odour and taste neutrality. This process gives a very high yield of fibre from the tim- ber. The presence of lignin in the pulp makes the fibres Recycled hard and rigid. This produces a paperboard with high This separation and recycling process utilises a wide vari- stiffness, limited strength, low density and lower resil - ety of waste paper and board. Each time a fi bre is recycled i ence. Mechanically separated virgin fibre pulp contain- it is contaminated and shortened and its capacity for con - ing lignin reacts more strongly to changes in external solidation is reduced. This means that virgin fibre must environment, humidity and temperature, a reaction that be added to maintain the quality of recycled pulp. Recy- can have a negative effect on flatness and dimensional cled pulp is carefully cleaned and screened during stock stability. preparation. Mixed waste paper is not usually de-inked As a result, paperboard made solely from mechanical for paperboard manufacture and hence the pulp may pulp is relatively weak. The paperboard retains the yel- retain traces of inks, adhesives and other residues which lowish colour of the wood used and is pure because it together give this kind of paperboard a grey colouration. is made solely of natural and known raw materials. The resulting product has less predictable composition and poorer functional properties than virgin fi bre-based boards.

Mechanical pulp Chemical pulp

IGGESUND PAPERBOARD | Reference Manual 19 Choices of raw material

In addition to the types of fi bres and pulp, the construction and coating of the paperboard sheet also affect the paper- Coating board’s fi nal properties. Selecting and combining types of fi bres, the pulp preparation process, sheet construction and coating give the paperboard the fi nal properties it needs to meet a wide variety of market demands.

Solid bleached board (SBB) Bleached SBB is made exclusively from bleached chemical pulp. It Bytas ut till 3-skickt , Elisabethchemical pratar pulp usually has a coated top surface and some grades are also med elena coated on the reverse side. The term SBS (Solid Bleached Sulphate), derived from the method of pulp production, is sometimes used to describe this product. This is a medium density paperboard with excellent sur- face printing properties to meet graphical and packaging needs. It gives a wide scope for structural design and can SBB cross section be cut, creased and embossed with ease. It is a pure and hygienic primary fi bre paperboard and is suitable for the packaging of aroma and fl avour sensitive products. Coating

Bleached Folding box board (FBB) chemical pulp FBB comprises middle layers of mechanical pulp sand- wiched between outer layers of chemical pulp. The top layer of chemical pulp is bleached and pigment coated. The back of the paperboard is cream (manila) in colour. Mechanical This is because the back layer of bleached or unbleached pulp chemical pulp is translucent, allowing the colour of the middle layers to infl uence the appearance. The back layer may, however, be thicker or have pigment coating – this product is known as White Back Folding Box Board. The Unbleached combination of inner layers of mechanical pulp with outer or bleached chemical pulp layers of chemical pulp creates a strong and stiff sheet, taking advantage of the well-known I-beam principle in physics. The mechanical pulp can be of CTMP (Chemi- FBB cross section thermomechanical pulp), RMP (Refi ner mechanical pulp) or TMP (Thermomechanical pulp) origin. This is a low den- sity material with high stiffness. Fully coated grades give Coating excellent printing and visual impact. This is a primary fi bre paperboard with consistent purity for product safety.

Solid unbleached board (SUB) SUB is made exclusively from unbleached chemical pulp. The base board is brown. To achieve a white surface it Unbleached chemical pulp might be coated, sometimes in combination with a layer of bleached, white fi bres under the coating. The paperboard is used where there is a high strength requirement, e.g. carrier sleeves, liquid packaging, etc.

SUB cross section

20 Reference Manual | IGGESUND PAPERBOARD Choices of raw material

White lined chipboard (WLC) WLC comprises middle plies of recycled pulp. The top lay- Coating er or liner of bleached chemical pulp is frequently pigment Bleached coated. The second layer or underliner may also comprise chemical pulp bleached chemical pulp or mechanical pulp. Bleached The reverse side layer can be made from specially reclaimed pulp selected recycled pulp or may be white through the use of bleached chemical pulp. There are additional grades of unlined chipboards with coloured (dyed) liner plies. Selected waste This is a medium density product which is widely used in general packaging. It is diffi cult to generalise about WLC because of the wide range of qualities available. Selected waste or unbleached chemical pulp

WLC cross section

Abbreviations/keys According to DIN 19303

GZ Coated SBB SBB Solid Bleached Board AZ Cast Coated SBB FBB Folding Box Board GC1 Coated FBB, white back SUB Solid Unbleached Board GC2 Coated FBB, cream back WLC White Lined Chipboard GN Coated SUB, white or brown back G Gestrichen, coated GT Coated WLC, cream or white back U Ungestrichen, uncoated GD1 Coated WLC, grey back (spec.volume >1.45 cm³/g) A Gussgestrichen, cast coated GD2 Coated WLC, grey back (spec.volume 1.3 to 1.45 cm³/g) Z Chemisch gebleichte Frischfasern, bleached virgin GD3 Coated WLC, grey back (spec.volume <1.3 cm³/g) chemical pulp UZ Uncoated SBB C Holzstoff, virgin mechnical pulp UC1 Uncoated FBB, white back N Chemisch ungebleichte Frischfasern, unbleached UC2 Uncoated FBB, cream back virgin chemical pulp UT Uncoated WLC, cream or white back UD Uncoated WLC, grey back

IGGESUND PAPERBOARD | Reference Manual 21 Differences paper and paperboard

Differences paper and paperboard

Defi nition of the term paperboard varies. According to the The existence of a middle ply enables the paperboard ISO standardisation body, a paper product with a gram- maker to optimise surface characteristics in the outer mage exceeding 200 g/m² is called paperboard; however plies without losing stiffness and paperboard converting the defi nition by the Confederation of European Paper In- advantages which are built in to the middle ply. The dual- dustries, CEPI, reads “paper is usually called board when ply or single ply construction will always lead to one or it is heavier than 220 g/m²”. Paperboard can be made in more compromises. Features which are easier to optimise a single ply or, more commonly, in several plies (multi-ply). in a multi-ply construction than in a single ply construction For quality reasons paperboard usually requires a com- without compromising are: bination of several layers of fi bre in the wet state. When • bulk studying the traditional paperboard market one can see • strength that multi-ply paperboard is already made at 160 g/m². • stiffness both through high thickness and strong outer Two clear features distinguish paperboard compared plies to paper: • surface smoothness in combination with desired • Paperboard contains a greater proportion of long fi bre strength or stiffness achievements than paper. • functional features in the respective plies such as in- • Paperboard does not normally contain fi llers. creased moisture resistance in surface or middle plies. At Iggesund Paperboard we claim that paperboard is a The ability to alter all these parameters has resulted in a heavier paper product of multi-ply construction. wide range of products in the industry which target certain The advantages of the multi-ply construction lie in the applications and end uses by tailoring features, as can be ability to optimise fi bre characteristics in the different plies seen in the following pages. The advantage of a multi-ply to reach certain functionalities. This is done by varying the construction in a paperboard mill is that the quality can be content in each ply. The main features to vary are: adapted to different end uses by utilising the possibilities • proportion of long and short fi bres in the respective plies of fi ne tuning the features mentioned above. This makes • type of pulping method it possible for one supplier to manufacture and supply • treatment of pulp to improve strength or bulk quality and paperboard to meet the demands of several different end distribution of broke in the structure. uses, whereas a single-ply or dual-ply producer has more To be able to fully utilise the potential of optimising char- limited possibilities. acteristics in the paperboard it is crucial that the multi-ply construction consist of at least three plies.

Coating

Top ply

Centre plies

Bottom ply

Cross section of a multi-ply paperboard

22 Reference Manual | IGGESUND PAPERBOARD Differences paper and paperboard

IGGESUND PAPERBOARD | Reference Manual 23 Differences paper and paperboard

Characteristics of paperboard manufacture The wet end In the beginning of the 20th century the production and Paper and board are today produced both on a single wire distribution of goods and food products increased and so machine and on a multi-wire machine. did demands for better protection of these items. A cheap A board manufacturer selects the multi-wire construc- and easy solution was to use boxes made of thicker paper. tion of the wet end to meet the required surface, stiffness A change in the retail industry at this time from selling and strength properties. products in loose bulk to selling products that were pre- For a board maker with a multi-wire machine, the ideal packed placed demands on packaging to be used not only method is to combine different types of chemical fi bres in for protection but also for display. It became more important the outer layers to achieve strength and good surface pro- to attract the consumer to recognise a product in the store perties, and then to use one or more centre layers made and pick up a specifi c product for purchase. of more bulky fibres. Fibres produced by a mechanical Papermakers had to specialise in order to meet box con- pulping process provide more bulk and are often used by verters’ demands for strong and stiff boxes which protect board makers in the centre layers. the products from collapse during transport and which also Single-wire machines permit fewer possibilities to opti- provide good printing and display functions. mise bulk, and board makers must compromise more Traditional thick paper was no longer good enough. As between stiffness, strength and surface properties. a result, the fi rst paperboard machines were developed in Board manufacturers who use virgin fi bre are able to the United States. specialise and optimise the sheet better, although board Board machines are commonly built for optimum produc- manufacturers who use recycled fi bre will use similar tech- tion between 200 g/m² and 1000 g/m² while paper machines niques in how they select and refi ne the fi bre. have their optimum production grammage range from 70 to 200 g/m² depending on the intended application/end use. The press section From the layman’s point of view, a paperboard machine Physically pressing out the water from the sheet in the and a paper machine can appear to be very similar. The dif- press section uses less energy than evaporating the water ferences lie in the details. To examine these, we must look at in the drying section of the machine. the different sections on the two machines’ confi gurations. For a board maker, it is essential not to destroy the strength and bulk properties of the sheet (which have Fibre selection and stock preparation been built up in the wet end of the machine) in the press For a board maker, the selection and refi ning of fi bres section. At the same time, it is important to press out as depend both on the specifi c surface properties required much water as possible so as not to lose economy of for printing and display and on the requirements for box production. converting and the subsequent protection of the box’s Over the years, board manufacturers have developed contents. press sections that are more forgiving and have a longer Using strong and long chemical fi bres from softwood press nip in order to achieve a high dryness of the sheet in the outer layers of a board and more bulky fi bres in the before entering the drying section without compressing middle layer is ideal for achieving the relevant stiffness and the sheet too much and destroying its bulk, stiffness and strength properties. strength. Chalk is cheaper than fi bre and is often used by paper- makers to reduce cost, improve opacity and improve sur- The drying section face properties. However, chalk cannot be used by board There is no major difference between a board machine and makers because doing so results in a deterioration in the a paper machine. The drying section will typically consist strength properties of the board. Both board and paper can of a number of steam fi lled cylinders in contact with the pa- be made from recycled fi bres but the same issue of strength per or board; the number used will depend on the amount arises, because recycled fi bres are weaker than virgin fi bres. of water to be evaporated. The steam pressure in these Stock preparation for board makers must be optimised cylinders will be adjustable to control the rate of evapora- for stiffness, strength and surface properties. In contrast, tion and the fi nal moisture content. papermakers can focus solely on surface properties. In producing board and paper for packaging foods, fatty Calendering foods or liquids, manufacturers add chemicals to prevent Pre-calendering is used to make the surface of the uncoated the fi bres absorbing grease or liquid from these contents. base paper or board as smooth and even as possible so as Chemicals used for this type of application must comply to prepare the sheet for the subsequent coating operation. with regulations and directives from the EU and from the Finish calendering or gloss calendering is used to improve FDA in the United States. the coated surface and/or increase the gloss of the paper.

24 Reference Manual | IGGESUND PAPERBOARD Differences paper and paperboard

100 μm

Cross section of paperboard

Both paper- and board makers also use calendering tech- neutral. Accordingly, the chemicals used in the coating niques to achieve improved surface properties. However, must meet all the relevant safety requirements. excessively hard calendering can easily destroy the bulk of the sheet and thus the stiffness and strength properties of Winding, slitting and sheeting the board. There are no major differences between paper- and board Various types of calendering techniques have been makers with regard to the winding, slitting and sheeting developed in the board industry such as soft nip, long nip operations. In order to provide the correct end user ap- and metal belt calenders. Using these techniques it is pos- plication and be able to guarantee that the paperboard sible to improve the surface without reducing the bulk. has been produced under carefully controlled conditions, board makers must have a system of full traceability Coating throughout the process. The coating operations for paper and board are basically the same. The difference lies in the coating recipes. Board manufacturers have different requirements than paper manufacturers, depending on the intended application. Converting board into boxes carries specifi c demands, such as suitability for gluing functions. These must be taken into account when optimising the coating recipe and testing its suitability. Because one of the function of packaging is to protect and not to contaminate its contents, liquid board and board used to package food must be taint and odour

IGGESUND PAPERBOARD | Reference Manual 25 Fibre to board

Fibre to board

Today’s processes of separating fi bre and making paper- compost and road-building material. Using the entire tree board take place in facilities characterised by capital is an important part of our ambition to carry out sustain- intensity, high production volumes and the application of able production. the latest techniques of materials handling, continuous production and process control. From timber to fi bre – the pulping process In many cases, including the mills of Iggesund Paper- The timber logs which are delivered to the pulp mill are fi rst board, the production of pulp and the manufacture of debarked, since bark does not contain fi bre suitable for paperboard are carried out on the same site in a continu- pulp manufacture. Bark is removed by friction, as logs are ous integrated process, giving benefi ts in quality, effi ciency tumbled together in a rotating drum. The bark is then used and economy. as a fuel within the mill or composted to create garden soil. Managed forests provide the primary source of cellulose The next process depends on the type of separation or fi bre from wood varieties such as spruce, pine and birch. defi bration process used. The fi bre is separated by mechanical or chemical pulp- ing and the whiteness and purity may subsequently be Pulp manufacture improved by bleaching. Basically the choice is between long fibres (spruce and Processing on the paperboard machine starts with the pine) and short fibres (birch). The boardmaker optimises formation of a layer of entangled fi bres on a moving wire sheet forming, appearance and performance properties or plastic mesh from which water is removed by drainage. with an appropriate choice and blend of fi bres to meet the Further layers of pulp are usually combined in the wet state. needs of particular products. More water is subsequently removed by pressing and dry - ing. Paperboard is coated on-line or off the machine to improve the printing surface. Large diameter, full machine- width reels are produced by the machine. These reels are subsequently cut into smaller reels or sheeted, labelled, and wrapped prior to dispatch to the customer.

The forestry cycle The virgin fi bre for paperboard is derived from naturally occurring species such as spruce, pine and birch, which provide fi bres with suitable characteristics. These species are supplied by managed forestry operations in Sweden and other parts of Europe. To maintain sustainable development, including the re- quirements for biological diversity, modern forest manage- ment makes use of several combined methods. Detailed planning is done at both a county and local level. Natural regeneration, planting and sowing are used. Biologically sensitive areas and old growth forests are protected ac- cording to the local conditions. Another important characteristic is that managed for- PLANTING 0-3 years estry is an integrated operation whereby wood for pulping HARVESTING CLEANING 30-50 years UK 3-15 years UK is harvested with wood for the timber industry. Thinnings, 80-120 years 3-30 years Sweden the smaller diameter trees taken from the forest at vari- Sweden ous stages to allow other trees room to mature, are used sawn timber to produce pulp. When mature trees are harvested, the thicker part of the trunk is used as sawn timber, and the pulpwood tapered top goes to the pulp mill. This ensures maximum use of the harvested timber. Making the best use of raw materials is a key principle THINNING pulpwood within Iggesund Paperboard. The trees supplied to the 15-30 years UK mills are transformed into paperboard – but also into the 30-80 years Sweden energy that drives the production process, heats nearby homes and dries sawn timber. Other end products are soil

26 Reference Manual | IGGESUND PAPERBOARD Fibre to board

IGGESUND PAPERBOARD | Reference Manual 27 Fibre to board

Mechanical pulp characteristics which the debarked logs are fi rst converted into small fl at This process gives a very high yield from the timber. The chips. These chips, with a moisture content of 25–30 %, presence of lignin has a number of implications – the fi bre are forced between the rotating metal discs of a refi ning is hard and rigid and this gives the sheet a limited degree machine. The heat and water vapour generated soften the of consolidation, high bulk (low density), resilience, dimen- lignin so the fi bres can be separated. The pulp is screened sional stability, and stiffness. and cleaned and fi bre clumps are reprocessed. The presence of lignin and the limited degree of consoli- Mechanical pulping results in a very high yield. About dation would make a sheet made solely from mechanical 95 % of the wood is converted to fi bre. Mechanical fi bre pulp relatively weak. The pulp retains the colour of the separation requires high levels of electric power, and some wood used and is of known natural composition and purity. of the energy is usually recovered and used as heat in the Refi ner mechanical pulp (RMP) is a two-stage process in process.

Washing Logs Chipping + of raw De- and Refiner barking defibration Bleaching Pulp to material washing board mill

Bark for fuel or compost

CONVEYORS

Metering EXCESS CHIPS Screw RECIRCULATE WOOD Conveyors CHIP Preheater Preheater Preheater SILO

REFINER CHIP WASHER AND DEWATERER

BLEACHING

REFINED FIBRE

To screens and cleaners

28 Reference Manual | IGGESUND PAPERBOARD Fibre to board

Chemical pulp characteristics solve 80–90 % of the lignin, allowing the fi bres to separate This process preserves fi bre length and the pure cellulose easily. develops a high degree of consolidation, both features that The sulphate process, which is used within Iggesund, give a very strong sheet. also permits effi cient chemical recovery and energy utilisa- The fi bre is fl exible and soft, giving good creasing, emboss- tion. The fi bre yield of unbleached chemical pulp relative to ing, and cutting properties and with low dust generation. wood is in the range of 50–65 %. The dissolved lignin and Bleached cellulose pulp has high whiteness, brightness, resins from the wood are used in internal energy generation. and light stability. This material has the highest purity and provides products with the best odour and taint neutrality. In the chemical process timber is fi rst converted into wood chips. These are then cooked in chemical solutions to dis-

Washing Logs Chipping Washing Oxygen De- Impreg- Continuous Diffusion + of raw and and delignifi- barking nation cooking bleaching Pulp to material washing straining cation board mill

Chemical Bark recovery for energy fuel generation

DEFIBRATION CHIPS

O2

NaOH Modified continuous Pressure Double Oxygen delignification Final wash cooking diffuser wash straining

PULP

CIO2 CIO2 O2

NaOH H2O2 CIO2 CIO2 DIFFUSER BLEACHING

IGGESUND PAPERBOARD | Reference Manual 29 Fibre to board

Caustic soda/ High pressure steam sodium sulphide solution (white liquor)

Chips + liquor

IMPREGNATOR DIGESTER

Chips Forward flow cooking

Caustic Reverse soda/ flow sodium cooking sulphide solution (white liquor) Black liquor in recycle loop

Wash liquor

Impregnated chips Pulp (incl. liquor)

30 Reference Manual | IGGESUND PAPERBOARD Fibre to board

Bleaching All these factors have technical and economic implications, All the varieties of pulp used in the manufacture of paper- not least of which is their environmental signifi cance. board can be bleached to infl uence colour and purity. Whitening methods fall into three categories: Chemical pulp is brown in colour, the colour density • Bleaching by delignification using chlorine gas. This depending on the cooking process and degree of lignin approach has largely been replaced by processes with removal. While unbleached pulp may be used for some better environmental safeguards. The use of oxygen is purposes, such as corrugated board boxes, it is neces- being progressively introduced instead. sary to whiten the pulp for many graphical and packaging • Bleaching by oxidation using materials such as chlorine applications. dioxide, hydrogen peroxide or sodium hypochlorite. The whitening of pulp is called bleaching, though the • Bleaching by reduction using materials such as sodium process can take many forms depending on a number bisulphite. of factors. These include the degree of colour change If the pulp mill is integrated with paperboard manufac- required, choice of chemicals, method of treatment and ture, the pulp is pumped to intermediate storage facilities. whether coloured compounds are removed (delignifi ca- If the pulp is sold to the open market it is dried in sheets tion) or merely changed in colour. or by fl uffi ng and drying in hot air. Market pulp is baled for shipment.

IGGESUND PAPERBOARD | Reference Manual 31 Fibre to board

Pulp (stock) preparation steel surface. A wet paperboard web will adhere to the cyl- If the pulp is bought in bales it is fi rst mixed by agitation in inder surface and be progressively dried while at the same water in a large vessel known as a hydrapulper. All pulp, time achieving a very smooth board surface. This cylinder including the pulp which comes straight from the pulp mill is known as an MG (machine glazing) or Yankee cylinder. without drying, is then treated in various ways to prepare it for use on the paperboard machine. The processed pulp Surface sizing is referred to as “stock”. The consolidation properties of A starch solution can be applied to the paperboard surface fi bre can be improved by mechanical processing – refi ning to improve strength and anchor surface fi bres fi rmly in the – which modifi es the surface structure of the fi bre. Swelling sheet. Within Iggesund Paperboard the baseboard is sur- in water expands the fi bres’ surface area, thereby increas- face sized prior to being coated. When board is surface ing their strength and ability to consolidate. sized a starch-based solution is applied to both sides of Additives such as internal sizing can be used to increase the product: this improves surface strength and anchors the water repellency of fi bres, and retention aids to increase the fi bres to the sheet. dry strength. Fluorescent whitening agents (FWAs), also known as optical brightening agents (OBAs), can be added Calendering as required to increase the whiteness. Passing the sheet through a series of nips between steel Discards and trimmings from the board making process rollers or a soft nip calender can improve its smoothness – called “broke” – are broken up and mixed into the stock and adjust its thickness. in varying amounts depending on which paperboard layer the stock is intended for. Finally, the “consistency” (fi bre/water ratio) is fi nely adjusted prior to pumping the stock to the paperboard machine.

Forming The fibre suspension in water, at a consistency of around 99 % water, is “formed” in several even layers on a mov- ing wire or plastic mesh. Each layer has a specific stock composition suited to the layer’s function in the board construction. The composition and properties of the stock depend on the amount of long vs. short fi bres, the kind of pulp, its degree of refi nement, retention properties, and the proportion of broke that has been added. The water is drained with vacuum assistance from the layer of entang- led fi bres. The layers are brought together in the wet state.

Pressing At the end of the wire section and moving at a speed of between 100–500 m/min the combined sheet or web is suffi ciently consolidated to briefl y support its own weight Surface sizing principle as it is transferred to the press section on an absorbent textile blanket. Here the board is pressed together with blankets between hard rollers and, with vacuum assist- ance, more water is removed, reducing the moisture content to around 60–65 %.

Drying The moisture content is further reduced to 5–10 % (de- pending on the product) by passing the sheet over steam- SURFACE SIZE heated steel cylinders. Some machines include in their drying section a very large heated cylinder with a polished BASEBOARD

32 Reference Manual | IGGESUND PAPERBOARD Fibre to board

Headbox Fibre suspension

Formed sheet

Wire

The forming process

H2O H2O H2O 98% 90% 80%

H2O H2OH2OH2OH2OH2O

The forming process

IGGESUND PAPERBOARD | Reference Manual 33 Fibre to board

34 Reference Manual | IGGESUND PAPERBOARD Fibre to board

Coating used is usually a calcium carbonate (ground marble), clay Paperboard products are coated to improve the appear- or a mixture of the two. The nature of the particles that ance of the product and also to improve performance make up the pigment has profound effects on the proper- during printing. ties of the paperboard. Calcium carbonate has a very high whiteness but a relatively low opacity. Clay has a lower The process whiteness and its use results in a smooth surface with a After surface sizing the board is coated using blade higher gloss level and higher opacity. The second largest coaters, air knife or curtain coating. In a blade coater the constituent of a coating is the binder, which is often a latex coating is applied to the baseboard using an applicator roll supplied as a water-borne emulsion. At this stage the latex or a jet applicator. The sheet continues up to a blade that is a large number of very small particles. When the latex removes the excess coating. The excess coating is recir- is heated during the papermaking process the latex melts culated and reused. Once the excess coating has been and forms a fi lm that binds the pigment particles to one removed the paperboard is dried prior to the application another and also to the baseboard. Many other chemicals of the next layer of coating. are also routinely added to coatings to improve the per- formance of the coating in the production process and The coating the performance of the fi nished paperboard. White pigmented coatings are applied to the print side of the board and sometimes also to the reverse side. These Brushing and glazing consist of selected mineral pigments and synthetic bind- Some paperboard machines incorporate equipment for ers, dispersed in water. Selection depends on product further surface enhancement by brushing and glazing. requirements and processing conditions. The application and smoothing technique ensures a specifi ed coat weight Reeling and smoothness. Smoothing may be by roll bar, air knife The fi nal process on the paperboard machine is to reel up or blade. There may be one, two or even three coating the paperboard in the full machine width to specifi ed reel layers applied to achieve the required appearance, colour, diameters. smoothness and printing properties. The largest component of a coating in terms of mass is the pigment. The pigment

PRECOAT TOPCOAT

COATING

SURFACE SIZE

BASEBOARDBASEBOARD

IGGESUND PAPERBOARD | Reference Manual 35 The paperboard machine

The paperboard machine

The basic features of a typical paperboard machines is 3. Drying shown below. The drying section allows optimal control over the drying process. The paperboard web passes over steam-heated, 1. Multi-ply forming polished cylinders which gradually reduce the moisture. In contrast to paper, Iggesund paperboards are built up A sophisticated system controls the temperature of the in several layers, or plies. Fibres are supplied via inlets cylinders to ensure that the web tension is under control (“headboxes”) at the wet end of the paperboard machine. during the drying process. Concentration at the wet end is approximately 0.3 % fi bres The drying section establishes a uniform moisture pro- and 99.7 % water. A low fi bre concentration is essential in fi le, fl atness and stability. order to obtain as uniform a distribution of fi bres as pos- sible in each layer. The fi rst layer is formed on a plastic wire 4. Surface sizing and the water drains downwards. The subsequent layers Here a starch solution is applied to one or both sides to are stabilised on two upper wires and water drainage is prepare the paperboard for coating. Surface sizing binds done both upwards and downwards depending on wire the fi bres to the surface, making the paperboard more and position. In the wet state, the layers of fi bre consoli- uniform and dense. date easily. Precision in the distribution of fi bres and the consolida- 5. Calendering tion of the fi bre layers is a basic condition for qualities such The paperboard is passed between rotating steel rolls to as fl atness, smoothness, strength and good creasing further increase surface smoothness. This process also properties. controls the paperboard’s thickness and density.

2. Pressing When the paperboard web reaches the press section, water content has dropped to 80–85 %. The press section is important for achieving the correct consolidation of the fi bre layers. Sandwiched between two fabrics (felts), the paperboard web is pressed between hard rolls. The water is effectively removed so that moisture content in the pa- perboard at the end of the press section is 60–65 %. 3 Here, qualities such as fl exibility, stiffness and runnability 2 are ensured. 1

1

1

36 Reference Manual | IGGESUND PAPERBOARD The paperboard machine

6. Surface coating 8. Reel-up The liquid, white-pigmented coating is applied and The paperboard web is reeled onto a large steel core, smoothed out over the surface with a blade on either together weighing 30–40 tonnes depending on the pro- one or both sides depending on the product. Each layer duct. Each fi nished reel of paperboard is given a unique is dried independently by infra-red and hot air dryers. identifi cation code which allows the product to be traced The surface coating section allows paperboard to be all the way back to the raw materials. coated twice on both sides to provide a high degree of whiteness, smoothness and gloss. Coating also deter- 9. Online measurement and control mines the surface’s ink and varnish receptivity. The web passes thousands of measuring points from which data is transmitted to the central control system. 7. Calendering and polishing Optical on-line measurement is carried out on the mov- The fi nal gloss of the surface is achieved by gloss calen- ing web to check thickness, grammage, coating weight, dering in a gloss calender or brush polisher. In the gloss moisture content, whiteness and gloss. The resulting calender the paperboard web passes between a heated regulation and control capabilities are a prerequisite for hard steel roll and a soft polymer roll. In the brush polisher uniform, high quality. the paperboard is polished by rotating brushes. These processes give a uniform, smooth surface – which is essential for good printing and varnishing. 8

9 7 9 3

6 9

5

4

BOARD MACHINE Moisture Moisture Moisture Moisture ONLINE MEASUREMENT Grammage Grammage Grammage Thickness Coat weight Thickness Fibre Coat weight orientation Gloss Optical Properties Optical properties Formation

STOCK

FORMATION SURFACE DEWATERING PRESSING DRYING SIZING DRYING GLAZING COATING GLAZING WINDING

IGGESUND PAPERBOARD | Reference Manual 37 Extrusion coating and lamination

Extrusion coating and lamination

Paperboard is coated with plastics to combine the me- • PP (polypropylene) and PET (polyethylene terephthalate) chanical properties of the paperboard with the barrier and are two heat resistant polymers that, applied on the board, sealing properties of plastics. Paperboard combined with can be used in oven applications. a relatively small number of plastic materials will provide • Aluminium foil and metallised polyester film may be the extra features needed to make the paperboard suit- laminated to the paperboard to provide a metallic effect. able for a number of specially demanding applications. Printing can be done on a pre-treated surface. Extrusion coating is a process whereby molten plastic is applied to paperboard and subsequently chilled to form an Functional coating extremely thin, smooth layer of uniform thickness. Paperboard as such is suitable for the packaging of dry The molten plastic can be used as an adhesive to lami- products in general. However, plain paperboard is only nate a plastic fi lm or a metal foil. suitable for direct contact with moist and greasy foods to Extrusion coating and lamination are used to achieve: a limited extent, because moisture will affect the mechani- • moisture protection cal properties of the paperboard, and absorbed grease • barrier to water vapour, oxygen, aroma, etc. will cause stains. Such effects will obviously reduce the • grease resistance protective function of the package and may detract from • heat sealability the appearance as well. • sales appeal, for example shiny surfaces. Extrusion coating or lamination adds a thin layer of plastic to the paperboard. Plastic coatings can provide Sales appeal resistance to grease and moisture and, where appropri- The use of extrusion coated and laminated paperboard ate, be heat resistant. Plastic coatings can be heat sealed provides outstanding promotional benefi ts in terms of and in some constructions these seals can be leak proof. visual appeal and consumer handling. Depending on the application, the paperboard may be High gloss is created by extrusion coating and a specifi c extrusion coated on one or two sides. high gloss chill roll. A metallic effect is created by lamina- Aluminium lamination provides packages with a barrier tion with aluminium foil or metallised polyester fi lm. These to light, moisture, grease and gases. The aluminium foil materials and processes also provide tactile sensations is often plastic coated to provide product safety and heat of high quality and luxury which the consumer associates sealing abilities. with high value products packaged in these materials. Key characteristics Examples of extruded and laminated products providing A number of process parameters infl uence the sales appeal grammage of the coating. The most important are: • PE (polyethylene) extrusion coating of paperboard with a • fl ow of the plastic melt gloss or matt fi nish. Printing and gluing (with cold glue) can • temperature of the plastic melt. be done on a corona-treated surface.

Print on a foil laminated paperboard where the metal details of the guitar is locked out of the photograph so that the metallic sheen underneath is entirely exposed

38 Reference Manual | IGGESUND PAPERBOARD Extrusion coating and lamination

The extrusion coating

Applications Description Examples

Liquids Ice cream and soft drinks require a good water barrier. Drinking cups Two side extrusion coatings are often required to main- tain the rigidity of the cups. First class runnability in the cup forming machine is an absolute necessity.

Frozen foods Frozen foods which are pre-frozen and packed as such Ice cream can usually be packed in one-side plastic coated paper- Frozen vegetables board. Other products, which are packed wet and even Seafood hot for chilling and freezing in the package, will generally require a two-side plastic coated paperboard to ensure that the package functions reliably all the way to the consumer.

Ovenable packs The packaging material must resist moisture and grease Baking using the pack- at elevated temperatures without penetration into the ages as a baking mould paperboard. The paperboard is given a heat-resistant plastic coating, which must not affect the taste or odour of the food.

IGGESUND PAPERBOARD | Reference Manual 39 Extrusion coating and lamination

Extrusion coating and lamination machine 3. Extrusion coating Plastic granules such as polyethylene (PE), polypropylene 1. Unwinding (PP) and polyethylene terephthalate (PET) are converted The paperboard is loaded into an unwinding position. by pressure and heat to the molten state in the barrel of the extruder. The molten plastic passes through a narrow slit 2. Surface treatment in the automatically controlled die and onto the surface of The paperboard surface is pre-treated with an electrical the paperboard. The control of temperature is critical. The corona discharge. The plastic fi lm can be treated with plastic surface is immediately pressed against the chilled ozone. These methods increase the adhesion of the face of a steel roll, controls the fi nish of the plastic surface. plastic to the paperboard. Reverse- side coatings have an NSO (Non-Set-Off) fi nish and print-side coatings usually have a gloss fi nish.

1

4

2

3 Extrusion lamination machine

3

40 Reference Manual | IGGESUND PAPERBOARD Extrusion coating and lamination

4. Extrusion lamination 6. Reel-up An unwind station is located immediately after the initial The paperboard is wound onto large steel cores (drums) plastic coating is applied. Foil or fi lm can be fed from this in batches of between 1 and 3 tonnes depending on the position into the nip between the molten plastic fi lm and product. Each drum is given a unique in-house identifi ca- the chill roll such that the plastic initially performs the tion code. functions of an adhesive.

5. Corona treatment Print-side plastic coatings are subjected to corona treatment to achieve good ink wetting. One-side plastic coatings are also corona treated to improve the sealing characteristics and permit gluing with emulsion adhesives.

4

6

2

3 5

Molten plastic Foil Molten plastic

Reel up Corona Ozone treatment Ozone Corona treatment Chill-roll

NSO Chill-roll

Corona treatment

IGGESUND PAPERBOARD | Reference Manual 41 Extrusion coating and lamination

Extrusion and lamination materials However, if the amount of the plastic barrier is below a cer- The materials used for extrusion coating and extrusion tain level (currently 5 % of the total weight) the packaging lamination are paperboard, paper, plastic resins, plastic material is regarded as a mono material from a tax point fi lms and aluminium foil. of view. There are well-proven processes in use today There are many types of coating resins and many of that can separate plastics and foils from the fi bres. These them have special features for specific end user appli- fi bres can then be used for the production of recycled fi bre cations. Film and foil suppliers produce both standard products. To facilitate recycling and maintain the quality of interchangeable products as well as their own speciality the recycled materials, it is always an advantage to sort at niche products. These can be combined with paperboard the source. to create a great variety of products. Plastic coating resins are selected for very low taint and Key properties required for extrusion coating and lamination: odour properties so that the packed products will not be • surface properties such as structure, smoothness, affected. strength and profi le European waste legislation stipulates that packaging • surface strength properties such as z- and tearing material should be easily separable to enable recycling strength and stiffness when possible. The plastic layer on extrusion coated • hydroscopic properties such as moisture, fl atness and material is by nature difficult to separate from the board, dimensional stability which makes it difficult to comply with these regula- • fl atness and dimensional stability tions. Mono materials, which are made from one basic • cleanliness of edges and surface raw material, are sometimes seen as better alternatives • polymer adhesion than composites such as extrusion-coated paperboard. • odour/taint neutrality. Composites exist because they are efficient and reliable in providing the required functions. Promoting mono Key properties for glue lamination: materials usually means sacrifi cing functional performance in addition to the above and adopting packaging materials with signifi cantly lower • surface water absorption effi ciency. • gluability.

Raw material Additional properties Applications

Polyethylene (PE) Good moisture barrier and sealability. Frozen food, ice cream, cups and confectionery.

Polypropylene (PP) Good grease and moisture barrier. Resists high tempera- Ready-made food for tures and is sealable. reheating in the package.

Polyethylene terephthalate Very good grease resistance at elevated temperatures. Trays for reheating and for (PET) The amorphous coating is heat sealable and heat resistant. baking.

Aluminium foil Good fl avour barrier and smooth surface with high gloss. Luxury products and chocolates.

Metallised PET fi lm Very high gloss and good printing characteristics. Good Gifts, wines and confec- fl avour barrier. tionery.

42 Reference Manual | IGGESUND PAPERBOARD Extrusion coating and lamination

Additional coating properties Pinholes The strength characteristics of the paperboard are slightly Pinholes are microscopic holes that might appear in the changed after extrusion coating and lamination. Plastic plastic film during the coating process. In most cases, coating with low density PE does not alter the stiffness but a limited number of pinholes is acceptable. The main PP or PET coatings will increase the stiffness considerably. reasons for the appearance of pinholes are irregularities The toughness of the resin gives increased tear strength to in the base paperboard (too high surface roughness, loose plastic-coated paperboard. fi bres, etc.), an uneven coating profi le or too low a plastic grammage. Plastic adhesion Plastic adhesion is a dimensionless property defi ning the Measurable properties relationship between the adhesive and cohesive strength Pinholes of the paperboard surface. The bonding should ideally be Coloured denaturised alcohol is applied on the test higher than the internal bond of the paperboard in order to surface. After 5 minutes the remaining liquid is wiped create fi bre tear. See Test Method in the Gluing chapter. off. Pinholes are indicated from the reverse side as Adequate adhesion is important for most converting green spots. The number of pinholes is expressed as operations, such as printing and heat sealing. number/m². For production control an internal method is used. The plastic coating or fi lm is pulled off at specifi ed angles and the degree of fi bre tear is determined. The ranking is: 6 = 100 % fi bre tear, 1 = no fi bre tear. If the strength of the paperboard/pigment coating is stronger than the bond between the paperboard and the plastic coating, no fi bre tear is achieved (e.g. fully pigment- coated paperboard). Then a different scale of evaluation is DROP OF INK applied and the ranking is: 6 = excellent adhesion, 1 = weak adhesion. In these cases the adhesion can also be measured TREATED PLASTIC SURFACE as peel strength at a 125 ° angle. The result is expressed as PAPERBOARD N/cm width. The plastic adhesion is mainly governed by: • surface properties of the baseboard DROP OF INK • pre-treatment of the baseboard (corona and ozone) • heat content of the plastic melt when applied to the paperboard. Corona treatment is necessary when: UNTREATED PLASTIC SURFACE • The plastic surface is to be printed (to enable the ink to PAPERBOARD wet the surface). • Emulsion glue is to be used (to enable the glue to wet the surface). Corona treatment also improves heat sealability. Two-side corona treatment is not available because such a material would give severe blocking problems between the sheets. The corona-treated plastic surface is extremely sensitive. Any rubbing, touching by hand, etc. will destroy the treatment. During production the corona level is mainly affected by mechanical damage. The moisture content of the paper- board can also infl uence the level. For two-side PE-coated paperboard we strongly advise never to stack more than two pallets high.

IGGESUND PAPERBOARD | Reference Manual 43 Board Lamination

Board Lamination

The basic paperboard products are produced in a limited Packaging that will come in direct contact with foodstuffs range of thicknesses because of the need for effi ciency must be designed for each specifi c end use. in paperboard manufacture. However, this thickness and stiffness range is extended considerably when two or Evaluation of paperboard lamination more layers of paperboard are glue laminated together Most of the evaluation is done off-line. The aim is to deter- into equal-sided products with the same smooth and mine and document that: white printing surface on both sides. The many raw materi- • the glue covers the whole web als available provide numerous combinations so that many • the glue keeps the webs together after drying customer needs may be met. • the sheets are fl at and free from twist Laminated paperboard offers good rigidity and smooth- • the pallets are fl at ness which, when combined with excellent visual appeal, • there is no damage (e.g. indentations) to the surfaces makes the package look more attractive to the consumer • there is no visible dust or loose particles that can disturb in the store. the converting operation. Laminated paperboard is smooth and fl at with good cohesion and adhesion. The combination of stiffness and converting possibilities makes it suitable for the packaging of expensive and luxury products.

7. Unwinding 10. Press Nip The glue lamination machine has four unwind stands. After gluing, the webs are pressed together.

8. Drying 11. Sheeting and Stacking IR (infra-red) driers are used to control the shape of the The glued board is sheeted and stacked on pallets in line. sheets.

9. Gluing Water-based adhesives are used to glue the board webs. 10

7

11

9

8 Glue lamination machine

44 Reference Manual | IGGESUND PAPERBOARD Board Lamination

Evaluation of extrusion coating and lamination Conversion operations in practice This process lends itself to control and continuous moni- Slightly different settings and techniques are necessary toring of the coat weight, coating profi le, thickness and with extrusion-coated and laminated products in printing, moisture profi les during production. die-cutting, creasing, gluing, and sealing. They are well The following properties are measured off-line: established and do not cause problems in practice. • adhesion Low odour printing inks and the programmed airing of • surface smoothness (printing side, reverse side) pallets are important to prevent the absorption of taint into • surface tension (treated side) the plastic coating. Always use well-proven procedures • pinholes as prescribed by the printing ink supplier. Uniform coat • fl atness of the sheet weight is important for successful conversion. • heat sealability (where applicable) When paperboard is glue laminated together to give a • odour and taint neutrality thicker and stiffer product, the following changes should • surface defects be considered: • blistering (where applicable).

Conversion operation Considerations for extrusion coated and laminated products

Printing Printing on a plastic-coated surface requires corona treatment of the plastic to make it wettable. In addition, the basically non-absorbent nature of the surface requires the use of printing inks that do not require absorbency. Such inks are available and they can also be used on pigment coated surfaces.

Die-cutting and creasing Plastic-coated or laminated products with an extra tough layer like PET should prefer- ably be die-cut from the plastic-coated side. In general, plastic surface layers improve creasability because they have very good elongation before breaking and tend to reduce the risk of surface cracking in the creases compared with plain paperboard.

Gluing Corona treatment improves the sealing characteristics and permits the gluing of one- side PE-coated paperboard with emulsion adhesives.

Packing The friction between the blanks should be considered, especially when they are made with a glossy PE on the outside. The glossy corona-treated surfaces may tend to stick together if not protected with printing ink or varnish plus spray powder. Such sticking or blocking tendencies may also appear in some packing lines if the un- printed glossy PE has to slide past polished steel guides. The remedy is to use varnish and spray powder on the exposed areas of the paperboard.

Conversion operation Considerations for glue laminated products

Printing Stiffness may make fl atbed printing necessary. Two-side pigment coating means that the reverse side is as smooth as the printing side. This can cause printing ink set-off.

Die-cutting and creasing Creasing must be carefully evaluated; the thicker products will need double creasing or scoring. Die-cutting and creasing will require higher pressure; this may affect the wear of the dies.

Gluing Gluing is done pigment coating to pigment coating. This procedure will be slightly differ- ent compared to gluing the printing side to the normal reverse side. The higher stiffness and different creases will give much higher spring-back force, so glue seams must be well developed before pressure is released.

IGGESUND PAPERBOARD | Reference Manual 45 Design and carton construction

Design and carton construction

How is paperboard used and how can you get the most process, which in turn affects the choice of paperboard. out of it as a material? Whether you are using the paper- The converter has to reproduce the ordered quality in board for a book or brochure cover or for a packaging it is such a way that it conforms with the agreed surface design important to have a detailed knowledge of how it should using the specifi ed paperboard. be handled and what demands will be made on it from the The best basis for achieving the desired visual impact various players involved in the chain between manufac- is by using paperboard based on primary fi bres with uni- turer and consumer or sender and recipient. Matching the formly white-coated surfaces with a high smoothness and requirements for an appealing design with the require- a good print reproduction. ments for cost-effective production, simple logistics and When discussing surface design we usually mean the good functioning in a retail environment is not an easy exterior or print side of the product. Aspects of surface de- task. In the following chapters we have chosen to focus sign, depending on the product and its use, may also ap- on functional requirements, mainly in the packaging chain, ply to the reverse side or inside surface. The inside surface before we go on to describe paperboard properties that may be printed, as with chocolate and cosmetics cartons, affect your choice of the most appropriate material. or it may be important to convey a hygienic image, as with The appearance of a package or graphical product is food and pharmaceutical packaging. decided during the design process. Paperboard is a ver- satile material which provides an almost endless number Examples of surface design of possibilities. This means that when designing shapes Features which can be used in surface design are de- the only limitation is your own imagination. The design scribed below. Often a combination of techniques comprises both the surface appearance and the shape is used. or structural design, and these two aspects of design are Text and pictures bring the product’s message to the discussed separately. customer. The shape and colour create an image for the Brand owners and designers need to have a good un- product. High whiteness together with smoothness give derstanding of the different stakeholders and their respec- good print reproduction. tive needs in order to make the most of the packaging and its potential. Key paperboard properties The decisive paperboard properties for achieving good Examples of infl uencing factors design are: • the brand itself • printability • the core product • whiteness • printer/converter • surface smoothness • packer/fi ller • ink absorption and drying • distributor • rub resistance • retailer • lightfastness • consumer • strength and elasticity. • legislation • non-governmental organisations such as environmental organisations.

Surface design The surface design of a packaging or graphical product based on paperboard comprises the effect of its print presentation with the possible additional use of varnish- ing, embossing, hot foil stamping, extrusion coating or lamination. The end user must defi ne and describe the surface design needs of the packaging or graphical product. This usually relates to the promotional and information needs concerning the product and its use. The designer has to prepare suggestions to meet the surface design needs described by the end user. This may have consequences concerning the choice of conversion

46 Reference Manual | IGGESUND PAPERBOARD Design and carton construction

Text, colour and images Description Achieved by

Printing Text and pictures bring the product’s message to the • choice of paperboard customer. The shape and colour create an image for the • print method product. High whiteness together with smoothness gives • post print fi nishing good print reproduction.

Metallic appearance A metallic appearance is effective in giving the product a • choice of paperboard luxury image. • aluminium foil lamination • metallised polyester fi lm lamination • metallic ink printing • hot foil stamping • cold foil transfer • effect varnishes

Glossy or matt appea- A way to attract attention is to create a contrast between • choice of paperboard rance glossy and matt areas of the design. • varnishing • gloss PE extrusion coating • fi lm lamination

Relief An overall effect such as a linen fi nish or high relief of • choice of paperboard specifi c parts of the design will give the product an • embossing & debossing exclusive image. • effect varnishes

IGGESUND PAPERBOARD | Reference Manual 47 Design and carton construction

Structural design An end user only sees the fi nal carton shape. The critical Paperboard is widely used for graphics and packaging aspects are good presentation, effective protection and applications where its versatile cutting, creasing, folding, durability, when prolonged or extended use is required. locking and gluing properties, together with its strength, From a sales or promotional point of view the visual appeal make it suitable for a wide range of functional and creative is vital. Structural design provides creative ideas for pro- structural designs. moting new products but perhaps the main responsibility Both creative shape and functional shape are important is to provide a functional shape which in the majority of aspects of the structural design. Packaging applications cases is based on accepted or specifi ed carton shapes. have to meet functional needs, such as protection during distribution and storage, and ease of handling and display Popular carton shapes at the point of sale, as well as fulfi lling the consumer’s de- The potential of paperboard to provide an almost end- mands. Creative design is used for promotional purposes. less range of carton shapes is considerable. Some of the The graphics designer has the freedom to use a wide more popular shapes are described in the following table range of shapes. together with the specifi c requirements these place on Critical aspects of structural design differ depending conversion and end use. on both the conversion and packing processes and also the ultimate end use. To a converter these are the quali- ties of stiffness, creasability and fl exibility and the ease with which paperboard can pass through the conversion process.

Type of carton shape Description

Simple rectangular or Simple rectangular or The rectangular or square cross-section with a large or square carton shape square carton shape main display panel is the most widely used carton shape. It is based on a simply cut and creased square or rectan- gular sheet, or blank, of paperboard. The carton is side seamed, leaving ends which are closed after the product is loaded. The product, method of fi lling and the way the pack will be stored and displayed will have a major infl uence on the dimensions. The ratio of the sides of the main panel is usually between 5:3 and 5:4 as these dimensions display well. This may not be possible if the product is an object or objects with differing dimensions. The rectangular shape also makes effi cient use of space in storage, distribution and merchandising. Shelf stability of the pack will also be taken into account in defi ning panel dimensions as well as the facings expected to be made available for display with products sold through supermarkets. The dimensions of the unit package also infl uence the dimensions of the transit outer (secondary packaging) and the pallet plan. It is worth considering the latter at an early stage as a difference of a few millimetres in one or two dimensions can signifi cantly affect distribution costs.

Hinge lid carton This style of carton is widely used for cigarettes. It includes a U-card inner frame, which assists the packing of the product, is part of the unique fl ip-top closure and increases the compression strength. Security and additional pack protection is achieved by the use of an overwrapped heat- sealed clear fi lm.

48 Reference Manual | IGGESUND PAPERBOARD Design and carton construction

Type of carton shape Description

Flanged and double- Flanged and double These designs give added strength and rigidity. A popular walled cartons walled carton use is for assortments of chocolate confectionery. They may have double-walled hinged lids or separate lids and bases.

Trays Two popular applications are available: Trays 1. Thermo-formed trays made from extrusion-coated 2 paperboard enabling lids to be applied by heat sealing. These trays may be slightly tapered. With a heat-resistant plastic extrusion coating, e.g. PET, these trays are used 1 for heating chilled and frozen foods in microwave and conventional ovens. These trays can also be used to cook bakery products. 2. Shallow trays (25–38 mm deep) with glued or locked corners to hold groups of cartons or other types of pack- ages for stretch and shrink wrapping.

Top load tray erected These cartons comprise a tray erected carton (glued or Top load tray cartons erected cartons locked corners) with a hinged top flap. The product is loaded from above, i.e. top load. There are two main types 2 of closure: 1. The top fl ap has an extended tuck in fl ap feature which tucks in and can lock into the front panel of the tray. This

1 type of pack is usually fi lm overwrapped for product pro- tection and security. 2. The top flap is extended on three edges which fold down over the outside of three of the sides of the tray and are sealed by hot melt adhesive. Alternatively, if the paperboard is PE coated on one or two sides the closure can be made by heat sealing.

Cartons with windows and plastic panels These cartons can be used to show the product inside the and plastic panels carton. The windows can simply replace cut-outs of the paperboard in one panel or form part of patented, more sophisticated systems in which the clear plastic incorpo- rates creases and replaces paperboard on two or more sides of the carton.

Display outers These cartons may have crash lock or lock end bases and Display specially designed top fl aps. The cartons hold a number outers of unit packages which are sold individually from the outer in a point of sale display. The top fl ap and, optionally, addi- tional portions of the side panels are creased and perfo- rated so that they can be opened and partly tucked down behind the product and the back panel, thereby attracting attention to and promoting sale of the product.

IGGESUND PAPERBOARD | Reference Manual 49 Design and carton construction

Type of carton shape Description

Lined cartons In this style a fl exible material (paper/PE, paper/foil/PE, etc.) is either positioned inside a side seam glued carton blank by the cartonmaker, or is applied on the packag- ing line. The base of the barrier material is then sealed or folded on the packaging line, the base of the carton sealed, product fi lled, pouch sealed or folded and fi nally is the carton the top carton fl aps sealed or tuck-in closed. Associated with this type of design are cartons incorporating plastic ends, tamper-proof, and product protecting diaphragms. These cartons can be used to protect sensitive products, they can be gas fl ushed or vacuumised, e.g. for coffee, and they can be liquid tight or provide protection against the ingress of moisture vapour.

Cartons with internal Cartons with internal These have paperboard fi tments inside the carton which display fi tments display fitments support and display the contents. The carton may have a top opening hinged or separate lid or it may be a windowed carton of the types already described. The fitments may be integral parts of the carton blank or separate structures added during the packaging operation. Another type of fit- ment is a divider. These can also be either an integral part of the carton blank or a separate fi tment.

Sleeves Paperboard sleeves can be wrapped tightly around other Sleeves items, e.g. a ready prepared meal in a lidded tray, “six pack” for plastic pots or other containers, or pre-wrapped prod- ucts such as cheese. The sleeves are sealed by either locking tabs or adhesive.

Sleeves with inner sliding components Typical examples are: sliding components 1. matchbox 2. hull and slide cigarette carton.

Other shapes of paper- Typical examples are: Other shapes of board packaging paperboard packaging 1. triangular shape, e.g. chocolate confectionery 1 2. hexagonal shape, e.g. chocolate confectionery 3. wallet style, e.g. hosiery 2 4. tubes, e.g. tubes with paperboard or plastic ends for 3 products such as confectionery and cosmetics. Other packages with a high degree of ingenuity in design. 4 They display the product and often use additional paper- board fi tments to support the product. Other additional confectionery products are often incorporated in the packages. These are usually, but not exclusively, associ- ated with confectionery and toy packaging where they have a play value after use. In other product areas they are associated with gift packing.

50 Reference Manual | IGGESUND PAPERBOARD Design and carton construction

Type of carton shape Description

Cartons for This feature can be incorporated by extending the back hanging artons for hanging panel of a rectangular fi tment display shaped carton, fold- ment display ing the panel over and tucking it inside the carton. A hole may be punched through two thicknesses of paperboard which may be reinforced with a plastic clip for merchandising.

Cartons with Interesting shapes can be created with curved creases curved panels Cartons with or straight creases meeting other creases at other angles curved panels than 90 °. Typical examples are: 1. curved panels 2 1 2. round corners.

Blister and skin A printed card, often printed on both sides, is used to packaging and skin support the product by either enclosing the product in a ging plastic tray, the fl anges of which are then heat sealed to the card or, alternatively, by folding extended panels of the plastic over the edges of the card or by draping clear plastic over the product and sealing to the whole area of the card.

Tubs For example ice cream tubs. Tubs of this type may also Tubs have circular paperboard lids.

Composite Granular powder products e.g. retortable packages. packages Plastic and foil containing laminates with paperboard.

Plastic-coated 1. For example milk, fruit juice. Two-side PE coated paper- barrier cartons board and other plastic foil laminations on paperboard. 2. Cartons with PE on both sides can have heat-sealed side and end seals which are liquid tight and can give moisture vapour protection to the contents. These cartons can also have PE on the reverse only, in which case they may be sealed with a fl exible diaphragm material having PE on one side to seal across the end closure.

Media There are different solutions for covers entirely out of CD paperboard. They can have sliding components, a perfo- rated or die-cut slit or folds that hold the discs.

IGGESUND PAPERBOARD | Reference Manual 51 Design and carton construction

Closure options. These features provide security and protection of The type of closure, opening feature and, where required, the contents during storage, distribution and at the point reclosure feature can be chosen from a number of design of sale and, subsequently, convenience for the consumer.

Types of closure Description

Glued or sealed end d or sealed, end The style shown has full-depth overlapping outer fl aps with the inner fl aps meeting. This gives a leak-proof style for powdered or granular products in direct contact with the paperboard. The inner fl aps never exceed the depth of the outer fl aps as this would lead to an uneconomical use of paperboard. The outer fl aps may be shorter than the depth of the carton, in which case they are known as economy fl aps. The most common type of adhesive used is hot melt, although emulsion adhesives are also used. The position and pattern of the adhesive applied can be varied to suit the needs of security, opening and reclosure. Alternatively, if the paperboard is extrusion coated with PE (or other thermoplastic material) on one or both sides, secure closures can be achieved by heat sealing, usually with hot air or direct gas fl ame.

Tuck end The top fl ap has an extended crease-hinged section which is folded through 90 ° and simply tucked down into the carton. With tuck-in fl aps at each end there is a choice of whether they tuck in on the same side or on the oppo- site side. Small cuts at each end of the hinged tuck flap crease give greater security against accidental opening. For greater security and product protection a heat-sealed transparent overwrapping fi lm can be used. An alternative is to overlap a self-adhesive label across the 90 ° angle between the end and main panel, i.e. over the tuck-in entry position. It is also possible to position adhesive between the underside of the tuck-in panel and the inner fl aps. The tuck-in cannot then be opened without rupturing this glued area.

Lock end Lock end 1. Used as the base of a carton with a simple tuck-in fl ap at the top. 2. The carton has extra cuts in each side panel fl ap for extra security. For greater security and product protection 12 a heat sealed transparent overwrapping fi lm can be used.

Crash lock The cartonmaker pre-glues this style, which is quickly Crash lock hand erected by the packer. It is usually used as the base of a carton and can support a considerable weight.

52 Reference Manual | IGGESUND PAPERBOARD Design and carton construction

Opening and reclosing features method of security is broken. There are several The tuck-end carton clearly has an effi cient method of opening designs for glued-end cartons – some of which opening and reclosure once the overwrapping fi lm or other incorporate reclosure features.

Types of opening Description

Tear strip If the overlapping fl ap is full or nearly full depth, a tear strip Tear strip Hot-melt adhesive on underside with a lead-in tab comprising two intermittent lines of cuts can be incorporated across the full width of the panel between the glue line and the flap crease. This design is not normally used for reclosure, though it can be to meet special needs.

Perforation Both overlapping flaps can be perforated in the same positions in two parallel lines so that by means of a lead-in tab both thicknesses of paperboard can be removed. This method of opening is not suitable for reclosure.

Pull tab The edge of the outer overlapping fl ap incorporates a tab to facilitate pulling and tearing – not suitable for reclosure.

Perforated press A push-in area is perforated in the top of the face panel, opening with the perforations extending and widening into the end panels, so that a clean tear-open is achieved, providing a partial reclosure.

Glue lines Normally, the glue line is continuous across the full width Interrupted glue line of the end fl ap. If, however, the glue line is not applied in the middle area, a fi nger can be carefully slid under the fl ap so that by breaking the glued area to the right and left it is possible to open the carton. Reclosure is achieved by inserting a tab in the outer fl ap into a cut in the under fl ap. Glue lines A variation of this form of opening is to replace the line of adhesive with a row of dots of adhesive which more readily break open. Another alternative allows the use of a con- tinuous line of adhesive. In this case the underlapping fl ap is printed and varnished, leaving small areas without print and varnish such that good adhesion is only achieved over these areas. The perimeter of these areas can be scored so that tearing is limited to the areas of good adhesion.

p Perforated panel A perforated area in one of the main panels of the carton can be removed allowing access to the product, e.g. facial tissues.

Concora Through a scoring (half-cut) on both sides (printed side + reverse side) of the carton, tear tabs can be worked out, guaranteeing a fail-safe opening of the packaging without the assistance of a plastic strip. PAPERBOARD The appearance of the sales packaging on the shelf will not be negatively affected by this scoring.

IGGESUND PAPERBOARD | Reference Manual 53 Design and carton construction

Conversion, packaging, and graphics fi nishing Key paperboard properties The following operations are used by converters, pack- The following paperboard properties are important for ers, and graphic fi nishers to make creative and functional achieving good structural design: shapes. • stiffness Creasing makes the paperboard fold accurately along • tensile strength well-defi ned lines. • compression strength Die-cutting produces a blank for further conversion. It is • box compression strength usually performed at the same time as creasing. Perfora- • tear strength tions can be used to facilitate opening. Tabs and slits can • creasability and foldability be cut in separate panels. When tabs are inserted into the • elasticity slits a self-locking permanent structure is created. • density Folding is usually performed to 90 ° or 180 ° angles. • plybond Gluing means applying glue on a side fl ap, pressing it to • lamination strength (for plastic coatings and laminates). a carton panel and maintaining the pressure until the glue seam has set. The paperboard is converted to a perma- nent shape. Heat sealing, heat and pressure can be used to seal plastic coated surfaces or surfaces to which a pattern of hot melt adhesive has been applied in an earlier operation.

Key paperboard characteristics Stiffness is probably the most important property related to packaging structural design. As we have seen, this property is closely related to other strength related fea- tures, such as fi bre composition, particularly in the outer layers, and thickness. Important considerations for carton panels are stiffness, panel dimensions, paperboard grade and fi bre orientation. Paperboard stiffness is anisotropic with respect to the machine direction (MD) and cross direction (CD). Box compression strength is closely related to structural design requirements. When packed cartons are stored or transported they are often stacked in such a way that the boxes are subjected to compression loading. In practice the strength require- ment of the fi lled carton is dependent upon: • Package design, i.e. shape and general strength due to the structure. • Whether the contents support the package or not. • Design and strength of transit package (the outer, etc.) • Storage and distribution method – palletisation, stacking and climatic conditions. • Conversion route – presence of barrier materials may be relevant in some methods of distribution. Carton design must take into account the stresses that are likely to be exerted on creases during the pack- ing process and also during end use. To this end, creases must be well formed to avoid premature failure under com- pression, and must also provide a crease stiffness that is suitable for the packaging operation. Folded creases and adjacent panel size must not exert unnecessary stresses during the gluing operation and subsequent handling and storage.

54 Reference Manual | IGGESUND PAPERBOARD Design and carton construction

IGGESUND PAPERBOARD | Reference Manual 55 Consumer use and appeal

Consumer use and appeal

The efforts of the manufacturers of paperboard, printers, Packages should be tamper evident, especially for food, converters, manufacturers and packers of goods, distribu- gift packages, and products for personal use. Adhesive tors, and retailers must ultimately ensure consumer appeal joints and opening devices must remain secure. Packages and satisfaction with cost-effective, effi cient packaging must not appear damaged or faded on the shelf, this being that has a sound environmental background. equated with old or badly handled stock. Packages which What are consumer needs? All consumers look for attract condensation after purchase, i.e. frozen and chilled “value for money” and “fi tness for purpose” and require a food and ice cream, should have good moisture resistance. clear demonstration of brand values and access to prod- With multi-portion packaging the consumer requires uct information. The information, form and functions need packages which are easy to open, close and reclose, to be adapted to demographic groups or individuals with and ultimately empty the package entirely. A perforated special needs. opening should be easy to tear, whilst a hinged tuck-in fl ap From a consumer’s point of view, the key requirements of must not tear after repeated opening and reclosing during packaging are to promote or provide: the life of the package. • product declaration Packaging should not deteriorate in use or storage, and • handling instructions proximity to other products should not be allowed to affect • brand recognition the fl avour or aroma of the product. • product protection An element of “convenience” is necessary depending on • oxygen-, light- and moisture barriers the product and the method of use. This can be achieved • convenience in a number of ways through the material and package • safety in use design, depending on the nature and use of the product. • recyclability • economic use of resources and accurate representation Key paperboard characteristics – not excessive nor deceptive As with retailing, the decisive characteristics are depend- • a responsible attitude to the environment ent on the type of product under consideration. • “intelligent” packages The consumer expects packaging to be effi cient and • and to separate and fi x the contents. functional and to meet needs in terms of the appearance Consumers expect packaging to be functional, easy to and performance requirements of specifi c products. The handle and safe to use. They require packaging to give properties of appearance and performance do interact; “easy recognition of product”, be “easy to locate” in the thus, for example, a poor appearance usually leads to store and refl ect the perceived value. Instructions for use a poor performance. Key characteristics as regards and disposal must be clear and distinct. These are all ap- consumer appeal primarily concern the cost effectiveness pearance features relating to the material, shape, decora- of paperboard packaging and its sound environmental tion, and printed matter. background.

56 Reference Manual | IGGESUND PAPERBOARD Distribution and storage

Distribution and storage

Distribution and storage comprise those activities occur- Key paperboard characteristics ring between the point at which the product is packed and The main requirement of both the individual carton or its ultimate point of sale in the retail store, supermarket, other forms of packaging is for stacking, handling, and vending machine, pharmacy, etc. transit protection. Stacking requires vertical compression At the end of the packing line the packages are collated strength. That may be assessed under static or dynamic by hand or by machine in groups of 6, 12, 24, etc. for loading on a pallet, a transit package or an individual pack- packing in a transit package. This may comprise: age. Handling of transit packages requires strength to • A shallow-depth paperboard tray which is subsequently resist impact and uneven compression in mixed loads. stretch or shrink wrapped in fi lm. Transport hazards usually refer to impact and can be • An open-ended corrugated fi breboard sleeve which is checked on sliding planes or by drop testing. Some sensi- subsequently stretch or shrink wrapped in fi lm. tive products may need special cushioning protection and • A corrugated case with glued or taped closure. There is the needs can be assessed on variable frequency vibration also a shelf-ready corrugated case which has a crocodile- tables and by the use of special records in practical transit type opening and is designed to go directly on the super- tests. Vibration can cause damage to the package by market shelf. scuffi ng or rubbing adjacent surfaces. • A unit of 6/12/etc. packs simply shrink wrapped in fi lm These requirements may also have to be met in frozen with no additional paperboard protection. (–20 °C to –35 °C), chilled (0 to +3 °C), very damp or wet These transit packages are usually palletised, alternate conditions, or very hot and dry conditions. layers being packed in a different pattern or plan to give stability to the load. The pallet load may be further stabi- Key properties lised with strapping or stretch fi lm. In general the strength-related properties are: Standard retail pallets are reusable with a common size • grammage being 1000×1200 mm. • thickness Pallet loads are stored in warehouses which may or may • moisture content not be heated. Frozen and chilled foods are stored in ap- • stiffness propriate conditions, i.e. –20 °C to –35 °C for frozen prod- • compression strength (short span) ucts and 0 to +3 °C for chilled products. Storage is usually • box compression strength freestanding, limited to two pallets high, or in racking. • water resistance (frozen and chilled food distribution). It is unusual for full pallet loads to be delivered directly from the manufacturer to the retail store except in the case Distribution and storage in practice of very large stores. Pallet loads are usually distributed to: The following factors are essential to good distribution and • Distribution warehouses of major retail organisations. storage: These are strategically placed to meet the stocking • The strength of paperboard requirements of a number of the company’s stores in a • The structural design of the unit package given area. Mixed loads are “picked” or made up to meet • The nature of the product, i.e. if it contributes to the the needs of the respective stores. This means that mixed strength of the package numbers of transit packages of different products are • The strength and structural design of the transit package placed in special cages, often in a somewhat random ar- • The pallet plan. The dimensions of the unit transit rangement. package can now be examined by computer to give the • Distribution warehouses of companies which are inde- optimum utilisation of the pallet volume. This also leads pendent of both the manufacturer and the retail stores. to the best stacking performance as a result of close and The procedure for distribution is the same as that de- interlocked packing on the pallet. scribed previously. Some additional comments are, however, necessary for • Distribution warehouses of independent cash and carry particular conditions of storage and distribution, see the companies. These companies display pallet loads of following page. goods in bays or racking allowing small retailers to pick the goods for themselves. This type of distribution has led to a more attractive cash and carry transit package, e.g. shrink wrapped to allow the more attractively printed individual cartons to be seen, or by the use of pre-printed white lin- ers for corrugated cases.

IGGESUND PAPERBOARD | Reference Manual 57 Distribution and storage

Summary other products with which it may be in contact, or to the Appearance needs are provided by surface and structural handling, storage and use of the product. design. Performance needs relate to printing, conversion Design in the broadest sense highlights every need which and use. This may involve special protection or functional must be incorporated into the choice of paperboard for every requirements relating to the paperboard product or to any graphical or packaging product.

Distribution and storage conditions Descriptions and actions

Frozen food and ice cream The storage temperature will be around –20 °C. The printed or varnished print must not craze at this temperature.

Chilled food The storage temperature is 0 to +3 °C and the main hazard is the very high relative humidity which raises the moisture content of the paperboard with a consequent loss of stiffness and strength. There are a number of ways of reducing this effect such as by using a tight sleeve where the product is in a plastic or aluminium foil tray, or by packing the product directly into a plastic coated paperboard tray with a printed heat sealed plastic coated paper- board lid. The paperboard can be made more resistant to moisture by: • Hard sizing all layers of the paperboard, thereby improving its edgewise wicking tendency. • Functional coating with plastic, aluminium foil, wax or moisture resistance varnish.

Very damp or wet conditions The paperboard can be given enhanced moisture resistance as discussed under “Chilled food”. These conditions also demand a coating on the paper- board and a choice of compatible inks and varnish with good keying, wet rub, and scuff resistant properties.

Very hot conditions Here the main problem to arise is blocking, i.e. the sticking together of sheets or packages. It is avoided by the choice of a suitable paperboard coating and compatible non-blocking inks and varnish.

58 Reference Manual | IGGESUND PAPERBOARD Distribution and storage

Edge water absorption, Wick test Surface water absorption, Cobb test In many wet applications such as deep-freeze packaging, The Cobb value quantifi es the amount of water absorbed or for drinking cups, a higher degree of water resistance via the paperboard surface during the Cobb test. is needed. Examples of the most demanding applications In the offset litho printing process, where water is used, might be the packaging of hot spinach, or cups for tea there is a need for some degree of water holdout. For or coffee. Even if the inside of the package or the cup is packaging applications for deep freeze/ chilled foods the plastic coated, the edges normally remain exposed. The requirements can be demanding. Wick test is the method commonly used to evaluate water The paperboard sample is weighed and a cylinder with absorption via the paperboard edges. a cross sectional area of 1 dm² is placed on the sample. The mechanism involves capillary attraction, which is Water (100 ml) is poured into the cylinder. After 1 minute reduced when the paperboard has been treated with a the cylinder is emptied and excess water blotted from the sizing agent. As only the paperboard edges are involved in surface. The weight increase is registered as the one- this test, the internal sizing of the paperboard and also the minute Cobb value in g/m². type of fi bre in use are of major importance. The test can be used for the outer surfaces as well as The test sample is covered on both surfaces with a the internal layers of a multi-ply paperboard. The centre waterproof tape and cut to a specifi c size. The sample is plies are tested after delamination of the outer plies. then weighed before being placed in water at 80 °C, so Hard-sized Folding Box Board products, where the that water can only be absorbed through the edges. After middle plies are additionally treated to give high water 20 minutes the sample is weighed again and the increase resistance for deep-freeze and chilled food applications, in weight recorded as the Wick test value in kg/m². This are tested using an extended time. The commonly speci- wicking test is used for testing of Solid Bleached Board fi ed time is 3 minutes, with the test also performed on the products. middle plies, in addition to the outer plies. On pigment coated surfaces water absorption is to a large extent dependant on the coating composition. For uncoated surfaces internal sizing and composition of the surface size are important. The internal sizing of fi bres is of vital importance in slow- ing down the water absorption of the centre plies.

Covered surface

Open edge

IGGESUND PAPERBOARD | Reference Manual 59 Retailing

Retailing

Retailing comprises the activities involved in offering Key properties goods for sale to the general public. Key paperboard features for the retailing process: In most cases the consumer can inspect the product • Print reproduction (whiteness, gloss, smoothness) and choose at the point of sale, stores and supermarkets. • Product protection (stiffness, compression strength, Retailers often market their own private brands alongside tearing resistance, water absorption, taste and odour other producers’ branded products. They are therefore neutrality) involved in all the aspects of package specifi cation, includ- • Designability (Good creasing, embossing and folding ing the choice of paperboard. characteristics, gluability) In case of mail order, internet sales, vending machines • Wide grammage and thickness range enables a well- and the issuing of prescription medicines in pharmacies, adapted choice, depending on protection and perform- the customer does not handle the goods prior to pur- ance need. chase. Packaging protection and information are vital to There is also an important environmental dimension for meet functional needs and emotional satisfaction (post- the manufacturer and retailer to consider which is con- purchase satisfaction). The package is the last part of the sumer driven. Certifi cation schemes, such as PEFC and brand communication chain, as it is often kept for storage, FSC, have been introduced to ensure a sustainable chain e.g. CDs and perfume bottles. of custody from the forest to the consumer. Details regard- The retailing requirements of a package are listed below: ing certifi cations are available on www.iggesund.com. • Brand appeal. • Transit packages for packaged and graphical products must arrive in good condition, thereby ensuring that the contents are also in good condition. • The transit packages should be convenient for transpor- tation, handling, opening, and recycling. • Unit packages should be convenient for stacking and display. They should be shelf-stable and make optimum use of the space available. • Unit packages should have structural and graphical designs which promote the product. The graphics should be appealing, distinctive and informative. • Unit packaging should provide appropriate protection for the product to prevent damage and maintain the quality of the contents. • Unit packages should conveniently conform to the needs of the retailer in respect of store handling, e.g. bar codes, ability to apply labels, provide tamper evidence, safety in handling and in packing at check-outs. Equally, the requirement to complete the sale safely and conveniently applies to mail order, internet sales, vending, and prescription dispensing. • Primary and/or secondary (display trays) packaging needs to conform to the retailers’ shelf space standards and to their standard transit packaging sizes.

Key paperboard characteristics These characteristics will vary depending on the type of product being considered. Guidance is given for major end uses at www.iggesund.com. In general the paperboard characteristics necessary will be those providing promotional and protective features. These features may vary from surface and structural appearance to box compression strength and taste and odour neutrality.

60 Reference Manual | IGGESUND PAPERBOARD Taint and odour neutrality

Taint and odour neutrality

One purpose of a package is to protect its contents from develops large amounts of volatile substances when dry- damage. For many products, such protection also in- ing. It is essential that the printed sheets are well dried and cludes preservation of the product’s fl avour. The package well aired to prevent problems. Modern “odourless” offset itself must not contribute to any unacceptable alterations inks, which reduce these risks, are available. by releasing or absorbing odorous substances which UV curing of offset inks is sometimes used to obtain a could affect susceptible products such as cigarettes very high gloss. In case of insuffi cient or irregular curing and chocolate. this printing technique can cause odour problems. Grav- Odour from paperboard can arise from a number of ure printing is often considered the safest method to avoid sources such as wood resins from mechanical pulp or odour problems provided the solvents are carefully chosen residual chemicals from chemical pulp. During the produc- and the drying is suffi cient. tion of the paperboard, biological activity may produce To detect and measure volatile and possibly odorous odorous substances. Furthermore, the coating contains substances in paperboard or paperboard cartons, gas synthetic binders, and there is a risk that these impart an chromatography is often used. Ideally, each volatile sub- odour to the paperboard. stance in the sample is represented by a peak in the chro- Mechanical and chemical pulps are selected to mini- matogram and the peak area indicates the concentration mise odour and steps are taken within the mill to eliminate of the substance. biological activity in the machine systems. The paperboard is tested on a regular basis to ensure that the risk of taint- The paperboard choice ing of food is minimised. In addition, coating materials are Paperboard that will be used for the packaging of sensitive subject to stringent specification and control to reduce goods such as foodstuffs or tobacco should be tested to tainting risks. ensure that it meets required taint and odour standards. Experience has, however, shown that by far the greatest As mentioned earlier, the surface coating composition and risk of tainting of sensitive products by cartons comes pulp are some possible sources of odorous substances in from the printing ink or varnish residues remaining in the the paperboard. Printing inks can also cause odours and paperboard after printing. Ink solvents and vehicles are different printing methods show major differences in odour often absorbed into the paperboard and may be absorbed contribution. by the fibres only to be released later. Paperboard may Both Folding Box Board (where mechanical and chemi- also absorb odorants during storage, and care should be cal pulps are used in combination) and Solid Bleached taken to store the paperboard in an odour-free area prior Board (where only pure chemical pulp is used) consist of to printing. primary fi bres, which means that their contents are known. Different printing methods can cause odour problems to Chemical pulp offers the least contribution to taint and varying degrees. Classical offset ink, based on drying oils, odour.

TYPICAL CHROMOTOGRAMS: WLC, FBB and SBB Time: 16,997 Minutes

IGGESUND PAPERBOARD | Reference Manual 61 Taint and odour neutrality

Characteristics of taint and odour neutrality Different pulp and coating characteristics A paperboard carton must be as free as possible of odor- Bleached chemical pulp contains cellulose and only traces ous substances which could originate from: of impurities. These are small amounts of fatty acids, resins • the pulp used in the paperboard and other impurities which could create odour problems. • the coating of the paperboard Fatty acids will oxidise in storage, if present, and develop • extrusion coating a “woody” or even rancid odour. • printing, lamination or other conversion steps. Mechanical pulp contains large amounts of lignin (wood substance) and resins containing fatty acids. A paperboard Assessment of taint and odour based on this type of pulp could contribute to taint and odour An optimised paperboard package will not interact with risks, but these can be diminished with a proper manufac- its contents in such a way that their odour and fl avour are turing technique and screening. changed. In order to be regarded as a good performer with Primary fi bres can be fairly well controlled but second- regard to taint and odour, a paperboard must therefore ary fi bres are often of unknown origin and have undergone have a very low concentration of odorous substances. various converting stages such as printing before being reclaimed and reused. This means there is a considerable

Chromatogram of unprinted paperboard

Chromatogram of printed paperboard

62 Reference Manual | IGGESUND PAPERBOARD Taint and odour neutrality

risk of inconsistency in the amount of contamination and In headspace sampling, the volatile substances that impurities in the paperboard, leading to variations in the are released are collected in gas form. In GC the volatile board’s taint and odour characteristics. A paperboard substances are separated through differences in boil- based on recycled fi bres is therefore not recommended ing points and absorption rates in the GC column. Their for the packaging of sensitive products. concentrations are recorded with a detector, normally a Most high-class packaging boards have a pigment fl ame ionisation detector (FID). However, the instrument coating to ensure good printability. The binders in the cannot differentiate between odorous and non-odorous coating are normally latices, which may contain various substances. To solve this problem it is possible to split the organic substances as impurities. Some of these could gas stream after the separation and lead one part to the create odour problems and must be carefully controlled. instrument. The other part is led to a person who sniffs the gas stream and notes whether there is a noticeable odour. Key properties For paperboard and cartons to be taint and odour neutral, Quality control the following features play a crucial role: For quality control two methods may be used. The fi rst • primary fi bre uses a panel which compares the outturn sample (either • the coating ingredients fi nished product or raw material) with a reference. In the • the plastic coating second a gas chromatogram is run to detect any new • the printing method used. peaks indicating contamination or to note major changes in the concentration of known odorous substances. Measuring equipment When evaluating a gas chromatogram it is important The most sensitive instrument available to measure the to select compounds which are known as risk factors if odour and/or flavour of a substance is a human being. they occur above the detection threshold. These com- Only humans can describe an odour or a flavour. The pounds are of course different for different applications; members of trained panels assign numerical ratings and for instance, cigarettes and chocolate are susceptible to record their impression of tainting flavours or volatile different compounds. odours experienced. By using no fewer than eight asses- sors, accurate and objective results may be achieved. Sampling and sample handling A number of sensory test methods are available. The To achieve proper measurements attention must be paid choice of test method is dependent on factors such as the to the sample handling. Due to the sensitive nature of this specific issue (e.g. type of products, type of questions) type of analysis some important issues are to avoid per- and how quickly the results are needed. fume and perfumed soap before handling the samples and Instrumental techniques are valuable complements to to use proper aluminium foil as protection for the samples. the human assessments. Headspace sampling combined Please consult the Laboratory for Sensory and Chemical with gas chromatography (GC) is used to measure chemi- Analyses for advice. cal compounds that are released from the products. To Iggesund Paperboard’s Laboratory for Sensory and identify the compounds, this method is combined with Chemical Analyses is accredited (accreditation number mass spectrometry (MS). 1740 ISO/IEC 17025) for the following analyses:

Type of test Methods Type of information Remark

Robinson EN1230-2 Intensity of taint resulting Scores (0 – 4) The standard test medium from interaction material – is ground chocolate but test medium. other media can be chosen.

Odour EN1230-1 Odour intensity of the Scores (0 – 4) The materials are put into materials. glass flasks and subse- quently the air of the glass fl ask is smelled.

Difference testing Triangle Pair-wise comparison The certainty of that there Two samples are compared. test (ISO 4120) Duo-trio (mod. ISO 5495). is a difference. Can be applied both to taint test (ISO 10399) and odour.

IGGESUND PAPERBOARD | Reference Manual 63 Taint and odour neutrality

Pieces equal to 2 A4 sheets are cut into strips

C 100% M 100% Y 100% B 100% TAINT TEST PROCEDURE

(LSCA)

PAPERBOARD 51 INK VARNISH

92 31

FOOD SIMULANT (CHOCOLATE) Stored in jar placed in indirect contact with the sample room temp, 2 days Chocolate assessed

A/D SAMPLE DETECTOR CONVERTER

INJECTOR CHROMATOGRAMS

COLUMN

COLUMN OVEN

CARRIER GAS COMPUTER

Gas chromatography principle

64 Reference Manual | IGGESUND PAPERBOARD Migration into foodstuffs

Migration into foodstuffs

The maximum amounts of substances allowed to migrate analysed (resulting in identifi cation and quantifi cation of into packed foodstuffs are limited by regulations that have the substances). been sharpened in recent years. To ensure that our board The limits apply to packaging materials made of several materials fulfi l the stipulated requirements, migration tests components. It is important to realise that while the board are performed. These tests bring different types of food is often the basis of the packaging, other components simulants into contact with the board and then store them such as printing inks and varnishes may contribute con- for specific time periods at a specified temperature. The siderably to the migration. type of test food and the choice of time and temperature Specifi c methods may also be used to analyse amounts depend on the intended use of the packaging materials. of certain substances, such as optical bleaching agents, After this contact period, the amounts of substances that are not well quantified when applying the more gene- that have migrated into the food simulant may be weighted ral migration tests. (resulting in an estimate of total migration) or specifically

FOOD SIMULANT (TENAX) Stored in migration cell Migrants dissolved placed on the sample in solvent

40°C 10 days

VARNISH INK PAPERBOARD

C 100% M 100% Y 100% B 100% MIGRATION TEST PROCEDURE (FABES)

1 dm² is cut Migrants identified and quantified (GC)

MIGRATION TEST PROCEDURE (FABES), OBA:s

PAPERBOARD ETHANOL+WATER

1 g cut paperboard Stored at 60°C, 2 days. OBAs in extract quantified (UV-spectrum) Migrants are extracted

IGGESUND PAPERBOARD | Reference Manual 65