26 The Carton Packaging Fact File CARTONBOARD 5 The Carton Packaging Fact File 27 KEY FACTS Cartonboard is a multilayered material. The main types of cartonboard are solid bleached board, solid unbleached board, folding boxboard and white lined chipboard. Cartonboard usually has a white, pigmented coating on one or both surfaces Cartonboard specifications Cartonboard can be vary with respect to the pulp combined with other composition of the various materials to vary the visual layers and by the grammage appearance and to extend (weight per sq. metre in the protective properties grammes) and thickness (microns or 0.001 millimetre) Laminations, coatings and impregnations can be added to extend the range of carton applications 28 The Carton Packaging Fact File CARTONBOARD COMMON ABBREVIATIONS SBB Solid Bleached Board SUB Solid Unbleached Board FBB Folding Box Board WLC White Lined Chipboard Different types and grades the range 200-600g/m 2 for grammage product aroma, flavour and hygiene are of cartonboard and their and 350-800µm for thickness. critical. Examples of cartons where abbreviations. The principles SBB is used are perfumes, cosmetics, of cartonboard manufacture, What are the main characteristics chocolates, pharmaceuticals, frozen developments and treatments of cartonboard? foods and cigarettes. Cartonboard is mechanically strong. What is cartonboard? Its stiffness, rigidity and toughness SBB is sometimes referred to as SBS Cartonboard is a multilayer material provide compression strength to protect or GZ. with, usually, three or more layers, or products in distribution and use. It can plies, of cellulose fibre (pulp) derived be cut, creased, folded and glued, giving What is Solid Unbleached Board? from wood. The various layers are the structural designer scope to produce Solid Unbleached Board (SUB) is combined in the wet state on the functional and creative packaging. usually made entirely from unbleached board machine and may comprise one chemical pulp and is brown in colour. or several different types of pulp. The surface is usually white and smooth It is also known as SUS or UZ. For and can be printed by all the main many carton applications the printing The top layer of cartonboard usually printing processes. Printing can provide surface either has a white pigment has a smooth white pigmented important product information and coating or a bleached chemical pulp coating based on china clay and/or attractive graphical designs. top layer plus coating. calcium carbonate. The reverse side may also be coated or it may be Cartonboard can be embossed and hot The board is used where either a very white, brown, cream or grey in colour foil stamped. It can be laminated to high strength (puncture, tear etc.) or depending on the grade of fibre used. other materials, such as aluminium foil, good wet strength properties are extrusion coated with plastics, such as required. It is also referred to as Carrier How is cartonboard classified? PE, PP and PET, and given treatments Board since in addition to folding Papers and boards are classified by which extend it’s range of appearance cartons it is used for multipack their fibre composition, the processing, and performance properties. applications in canning and bottling. manufacture and treatment at the mill, by grammage and thickness. Grammage What is Solid Bleached Board? What is Folding Box Board? is the weight of a square metre in Solid Bleached Board (SBB) is made Folding Box Board (FBB) comprises grammes (g/m 2) and thickness is exclusively from bleached chemical pulp. middle layers of mechanical pulp measured in microns (µm), that is, It usually has a white pigment coated sandwiched between layers of 1000ths of a millimetre. top surface, comprising 2 or 3 layers bleached chemical pulp. The top layer, and some grades are also coated on or, liner, is usually white pigment The crossover point between paper the reverse side. coated in 2 or 3 layers. The reverse and board is normally considered to side is cream (manilla) in colour as the be around 160g/m 2 as it is only at this SBB has excellent printing, structural back layer of chemical pulp is level that a fibrous material is likely to design and embossing characteristics translucent allowing the colour of the be stiff and rigid enough to make a making it ideal for luxury products and middle layers to show through. container. Most folding cartons are in for products where preservation of As noted in the discussion about The Carton Packaging Fact File 29 mechanical pulp, some producers to 100%. The top surface will, typically Why is cartonboard multilayered? of FBB apply a mild bleaching have 2 or 3 layers of white pigment Multilayering, that is forming the treatment to mechanical pulp to coating and it is now usual for most cartonboard in several layers, provides increase the whiteness. WLC to have a layer of white pigment important technical features and gives coating on the reverse side and this is flexibility in the choice of fibres (pulp) FBB with either mechanical pulp known as GT. WLC can be made with for each layer. It gives the cartonboard middles or bleached mechanical pulp a white, grey or, sometimes brown good stiffness, creasing, folding, and middles is described as GC2. reverse side (back). Plastic extrusion gluing properties. It also assists coatings, paper and aluminium foil grammage and thickness control. Where the reverse side or back layer laminations and other functional of chemical pulp is thicker and/or coatings are also available. It is particularly important to use good white pigment coated, so that the quality fibre in the two outer or surface appearance of both sides is white, WLC is used in a wide range of layers. This is because the fibres in the FBB is described as a White Back applications which includes cereals, these layers, or plies, experience the Folding Box Board or GC1. dry foods, frozen and chilled foods, greatest effect of externally applied detergent powders, confectionery stresses which can extend or FBB can be plastic extrusion coated, outers, toiletries, household goods, compress them in printing, conversion laminated with other materials and electrical, engineering products, car (creasing/folding) and use. given other treatments to enhance its spares, DIY, gardening, toys and appearance and functional properties. games. Special treatments are A wide range of applications include available to provide fat resistance and cosmetics, chocolate and sugar other barrier properties for uses in fast confectionery, medical and healthcare, food, pet food and soap packaging. toiletries, dry foods, frozen and chilled foods, coffee and tea, biscuits and What other boards are used baked goods, clothing, toys, games for cartons? and photographic products. A small number of cartons are made with 100% recycled unlined chipboard What is White Lined Chipboard? - this is grey on both sides. White Lined Chipboard (WLC), also known as GD, has middle layers of Cartons are also made from microflute recycled pulp made from mixed corrugated board. It is used to provide recovered papers or carton waste. additional protection for fragile products The top layer comprises either pulp such as glass, porcelain and sensitive made from selected recovered paper electronic and electrical goods, whilst at or bleached chemical pulp. Selected the same time providing a high standard recovered paper is also used for the of print and varnish appearance. back layer. The overall content of recycled pulp varies from about 80% 30 The Carton Packaging Fact File Typical solid bleached Typical solid unbleached board (SBB) construction board (SUB) construction 2 or 3 coating layers 2 or 3 coating layers bleached chemical pulp unbleached chemical pulp back coating layer Typical recovered fibre cartonboard Typical folding boxboard (FBB) whitelined chipboard (WLC) construction construction 2 or 3 coating layers 2 or 3 coating layers liner ply - waste pulp liner ply - bleached chemical pulp underliner ply - selected waste middle plies mixed middle plies mechanical pulp waste/carton waste back ply - selected waste back ply - pulp back coating layer back coating layer The Carton Packaging Fact File 31 How is cartonboard produced? Plastic extrusion coating with Many of the Folding Boxboards now Cartonboard is produced on the board polyethylene (PE), polypropylene (PP), incorporate middle layers of bleached machine in several stages. Firstly, a and polyethylene terephthalate (PET) mechanical pulp to improve the dilute suspension of cellulose fibre (pulp) or polyester, give various levels of brightness of the board. in water is formed into a thin layer of water and moisture vapour protection, entangled fibres on a moving plastic heat sealability, product resistance and There have been developments in mesh, known as the wire. Some of the heat resistance for ovenable surface coating methods, coating water is removed by drainage and packaging. Special varnishes provide formulations and board machine further layers of pulp are added to heat sealability for blister packs and processing, using techniques such as complete the grammage, thickness wax coating - “dry” waxing for surface glazing and brushing, which and composition of the cartonboard. moisture and product protection and have increased smoothness, The rest of the water is removed by “wet” waxing for high gloss, heat whiteness and sheet stability. pressing and drying, during which sealing and product protection - is This has improved visual appearance process inter-fibre bonding develops.