US 20150233058A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0233058 A1 Neumann (43) Pub. Date: Aug. 20, 2015

(54) BORAX-FREE STARCHADHESIVE Publication Classification COMPOSITIONS (51) Int. Cl. (71) Applicant: B.K. Giulini GmbH, Ludwigshafen D2 IIH 7/00 (2006.01) (DE) D2 IIH (7/66 (2006.01) D2 IIH 7/28 (2006.01) (72) Inventor: Michael Neumann, Mannheim (DE) (52) U.S. Cl. CPC ...... D2IH 1774 (2013.01); D2IH 17/28 (21) Appl. No.: 14/362,302 (2013.01); D21H 1766 (2013.01) (22) PCT Fled: Dec. 7, 2012 (57) ABSTRACT (86) PCT NO.: PCT/EP2012/074790 S371 (c)(1), The invention relates to paper or corrugated board produced (2) Date: Jun. 2, 2014 using aborax-free starch adhesive composition containing a dextrin, the starch adhesive composition being cross-linked (30) Foreign Application Priority Data with sodium aluminate in an alkaline medium, and the quan tity of sodium aluminate ranging from 1 to 35% absolutely Dec. 12, 2011 (EP) ...... 11 OO9577.5 dry relative to the quantity of dextrin. US 2015/0233058 A1 Aug. 20, 2015

BORAX-FREE STARCHADHESIVE 0014 Amylopectin is soluble in cold water and can be COMPOSITIONS used in this soluble form, while amylosis is non-soluble in 0001 Adhesives containing starch and dextrine have a water. Instead, it can be dissolved by cooking it in hot water major role to play in a wide range of industrial applications, in while adding strong alkali under pressure, mostly NaOH or at particular in the packaging industry. Starch and dextrine are 150-160° C. In its dissolved form, amylosis forms a disper used there for manufacturing packing paper and corrugated sion and solid gels at concentrations greater than 2%. Fur cardboard for gluing them. Furthermore, other porous Sub thermore, amylosis cannot be completely dissolved (at 100%) strates are glued with these adhesives. in water, and even crystalline aggregates form over time in 0002 Starch and dextrine are also very affordable raw these dispersions with H-bridges. This is a process that is also materials, easily available and they are frequently used as an called retrogradation. This process is responsible for the great aqueous dispersion because both can be used in the form of fluctuations in the Viscosity of adhesives containing starch. special formulations both cold and warm. Beyond this, starch and dextrines are used in powders dissolved in water to form 00.15 Adhesives containing starch have been manufac a relatively viscous paste. Finally, they harden with water tured state-of-the-art for the corrugated cardboard industry loss. with the Stein-Hall process since 1930. Starch-based adhe 0003. Although starch and dextrine have been used as sives/starch glues/are needed for manufacturing corrugated adhesives for a very long time, there are a whole series of cardboard that is a glued lightweight construction made of reasons why these natural adhesives cannot be replaced 100% paper. Therefore, along with paper, starch glue is the most by Synthetic products: important component for producing corrugated cardboard. 0004. They are easily available. The adhesive and gluing together have a Substantial impact on 0005. They are inexpensive. the quality of the corrugated cardboard. 0006. They have constant quality. 0016 Starch glue has the job offirmly bonding the smooth 0007. They bond well with substrates containing cellu sheets with the corrugated sheets. The deeper the starch glue lose and other porous Substrates. penetrates into the paper's pores, the better the bond. Beyond 0008. They are non-soluble in oils and greases. this, the product of corrugated cardboard is manufactured in 0009. They are not toxic and they are easily biologically a process where a paper sheet is initially corrugated on heated degradable. rollers. Afterwards, a sheet Such as this is applied on one side 0010. They are resistant to heat. by spreading starch glue on the tips of the flutes. This is then 0011. The table below shows the characteristics of some what is known as “one-sided” cardboard, even though there important types of starches: are also “double-sided cardboards. When manufacturing corrugated cardboard, it is unavoidable for the starch glue to form a fast bond between the paper surfaces. This is the maize wheat rice tapioca potato Sago reason why it is very important that the starch glue used has a origin COil CO COil root root COil Viscosity that makes it possible on the one hand to apply or corn diameter II S-26 3-35 3-8 5-25 15-100 1 B-70 spread the adhesive and on the other hand to allow it to be gelating temperature 62-72 S8-64 68-78 43-70 SO-68 60-67 bonded quickly enough. To determine the quality of the bond, C. the ripping test is used where the smooth sheet is torn off from approximate amylosis 28 25 19 2O 25 26 content of starch 96 the corrugated sheet with a piece of corrugated cardboard. approximate 70 75 8O 8O 75 74 The more fibre residues remain on the previous adhesive amylopectin content points, the better it was bonded. We can recognise excellent of starch 96 bonding from the fact that the two paper sheets can only be separated by tearing off the fibre. 0012. The proportions of the types of starch amylosis and 0017 Fast conglutination and bonding is supported on the amylopectin vary depending upon the type and sort of the one hand by the high temperature of application and on the starch plant. Since amylopectin is primarily needed for indus other handby including alkali, NaOH and boron compounds trial utilisation, starch plants with the highest content of amy such as boric acid or borax in the combination of adhesives. lopectin are preferred. For instance, the genetically modified Borax (that is chemically disodium tetraborate, NaBO7) is starch potato sort amflora is presently in the licensing proce used to control the stability, rheology and the surface wetta dure in the EU and its starch consists almost exclusively of bility of the starch adhesive during manufacturing and pro amylopectin while other barley sorts whose starch consists cessing. The quantities of borax vary from 1.5-20% atro with 95% of amylopectin are based on conventional methods of reference to the starch used depending upon the applications cultivation. Both products (starch and dextrine) are what are and type of starches. Adhesive producers and processers have known as carbohydrate polymers or more precisely the starch been recently limiting its use to 7% of borax. Viscosity is a natural polysaccharide. Only a few plants contain Suffi increases as soon as borax with a mixture of starch and alkali cient starch in their leaves, corns or roots, which is why these is added while stirring and heating and it remains stable over are the only plants Suited for extracting starch from them. a long period of time. This starch comes from wheat, maize, 0013 Starch contains two main components, amylosis potatoes, tapioca or peas that are modified naturally, chemi and amylopectin, where amylosis has long chains while amy cally, enzymatically or physically in accordance with the lopectin has a branched and chain-linked structure. This com general processes. Common yellow dextrines used in normal bination (and therefore this structure) varies from plant to production of adhesives containing starch are also suitable plant. However, one important property is its amylosis con just like those that are partially preconglutinated and partially tent since the greater the proportion of amylosis, the more Swollen and are used in the normal adhesive processes (such valuable is the plant for extracting starch. as Stein-Hall). US 2015/0233058 A1 Aug. 20, 2015

0.018 Disodium tetraborate in water and an alkali milieu gated cardboard industry. Finally, using borax is limited by reacts with starch in the following steps while forming a lower water solubility (it only dissolved 3-5%) and irritating water-soluble sodium starch borate: the mucous membranes when used in powder form. 0027. One suggestion has been using freebor as a replace ment in starch adhesive formulations. Apparently, this prod uct is a gel and has a stabilising effect on viscosity when O B(OH)+HO other potential cross-linking: adding it to starch glue. Unfortunately, neither the chemical (0022 4. Na"+starch-O-B(OH)+starch'-OH->Na"+ structure nor the formula of this bond has been revealed and (starch-O B(OH)O-starch')+HO there is also a safety data sheet without any data on its chemi Due to its toxic categorisation of reproduction toxicity (FD) cal nature. The assumption is that it is an acrylate gel. 18", borax has become a controversial raw material that the 0028. In any event, there was the urgent need to com corrugated cardboard industry would like to replace. Further pletely replace the borax in starch glue compounds used in more, borax has been on the list of the European Chemical manufacturing paper or corrugated cardboard while still Agency (ECHA) of the EU for chemical substances since maintaining all of the important properties Such as Viscosity, December of 2010. Solid matter content and pH-value. Beyond this, paper or 0023 The proposal has been made in U.S. Pat. No. 6,056, corrugated cardboard should be provided using a starch glue 816 to include another additive in the starch glue, namely an compound free of borax under simplified process conditions alkali silicate. Typically, this combination contains 12-35 and with short retention times while streamlining the appli weight % of starch, 1.5-12 weight % of soluble alkali sili cation conditions and energy costs. cates, 0.25-2.5 weight% of sodium hydroxide and as much as 0029. The above challenge is met in an invention where 2 weight % of borax or boric acid. The remainder of this paper or corrugated cardboard (produced using a starch glue formulation is water that might contain 55-70 weight%. The compound free of borax and containing one dextrine) is pro technical benefits of this composition are Supposed to be vided where the starch glue composition is cross-linked with higher viscosity, highly heat stability and higher Solid matter Sodium aluminate in an alkali milieu and where the quantity content of as much as 45 weight% of the finished composi of sodium aluminate is in the range of 1-35% atro with ref tion, in contrast to 15-35 weight% of solid matter content as erence to the use of dextrine. Surprisingly enough, it was per state-of-the-art (also refer to column 4, from line 25). found that using the sodium aluminate both in its liquid and 0024. Although these starch glue formulations are actually sold form guarantees the maintenance of these properties very well suited to the fast process of manufacturing corru while making the compositions completely free of borax. gated cardboard, there still have been other improvements This is a major benefit in terms of toxicity and industrial Such as by adding fillers such as calcium carbonate that have hygiene. also boosted the Solid matter content. EP 1 101 809 B1 0030 Sodium aluminate can be described with the general describes this. formula: NaAl(OH) or also Na2Al-Obecause the product 0025 EP2363 440 A1 describes adding a homopolymer contains more than the Stoichiometrically required amount of ofan C, B-unsaturated acrylic acid as per the general formula: Na20. This is also the reason why the NaO/Al2O ratio is CH=CR-COOH where R can be a substituent that is given to characterise it. Furthermore, sodium aluminate is selected from H. monovalent alkyl, aryl, or aralkyl radicals or also extracted with large-scale technology by what is known monovalent cyclical alkyl radicals, haloalkyls and as the Bayer development of bauxite or also by recovering cyanoalkyls, with 1-9 C-atoms. Claim 16 states that there is a aluminate waste lye arising in industrial processes such as the typical composition of 20-80 parts by weight (GT) starch, electrolytic oxidation process of aluminium. In general, 5-50 GT NaOH, 200-250 GT starch powder, 1-25 GT borax Sodium aluminates are produced when converting excess and 0.01-5 GT polyacrylic acid or 2-methacrylactic acid addi Sodium hydroxide solution with aluminium salts. Römpp tive. This invention also had the purpose of adapting viscosity Online, 2011 states that it is used in the following fashion: to manufacturing process (also refer to page 2, lines 35. “sodium metaaluminate is used for manufacturing Soaps, O008). papers, milk glass and paints in the enamel industry, as a 0026. In spite of these additives, the aforementioned com caustic in alizarin dyeing, for water softening, fresh water positions still contain as much as 2 weight % or 25 GT of processing, sewage purification by flocculating (in particular borax depending upon what the quantity ofborax referred to. in combination with other flocculation agents), as a water The Römpp-Online Chemielexikon states that borax should proofing compound and fast hardener in building dams, tun be avoided wherever possible, especially in packaging used nels and bridges. It also can catalyse reestering vegetable oil with food or for general human consumption. Römpp-Online, to biodiesel. The Sodium aluminate added to starch glue com 2011 also states that “borax smoke irritates the mucous mem position can preferably have a granulate or powder form. branes of the nose and throat”. Consuming greater amounts 0031 Since sodium aluminate dissolves well in water, this even causes stomach pain, vomiting, diarrhoea including cir makes it possible use it in the liquid and aqueous form, which culatory insufficiency all the way to a shock. It can cause is enormously beneficial to industrial hygiene because this inflammations if it comes into contact with the skin or eyes, makes it possible to avoid caustic dust pollution. This aque althoughborax does not attack intact skin; TRGS 900 (2009): ous solution has a pH-value of 11-12. Sodium aluminate workplace concentration 0.5 mg/m.” This is the reason why dissociates in water to Na' and Al(OH) ions that enter into it also has to be ensured in all corrugated cardboard works that the following reactions with the starch molecules in an alkali it does not exceed the maximum workplace concentrations. milieu. After forming a water-soluble sodium starch alumi Therefore, many manufacturers of corrugated cardboard are nate, they are cross-linked with a second starch molecule in a switching over to “liquid borax. Contact with the skin is the second step in condensation: most frequent means of contact with packaging. A replace 0032 1. Na+Al(OH)+starch-OH ->Na"+starch ment for borax is urgently needed in the packaging or corru O Al(OH)+HO US 2015/0233058 A1 Aug. 20, 2015

0033 2. Na+starch-O Al(OH)+starch'-OH increase in Viscosity with the beginning cross-linking reac ->Na+(starch-O Al(OH)—O-starch')+HO tion depending upon the mixtures. The finished adhesive with Acidification causes hydrolysis when forming Al-O. As low to highly viscous mixtures stays stable for a longer period Soon as the Sodium aluminate of the starch is dissolved in of time and can be used as starch adhesives for corrugated water is added while stirring and heating, the Viscosity cardboard and paper production. increases and it stays stable over a long period of time. The 0038 Sodium aluminate is used for controlling the stabil starch comes from wheat, maize, potato, tapioca or peas that ity, rheology and Surface moistening of the starch adhesive are modified naturally, chemically, enzymatically or physi during manufacture and processing on the Surfaces to be cally in accordance with the general processes. Special adhered. The quantity of sodium aluminate needed as per the degradable starches (namely dextrines) are used here. How invention ranges from 1-35% atro with reference to the starch ever, common yellow dextrines that are used in the normal and/or the use of dextrine. Polyphosphates can be worked into production of adhesives containing starch are also suitable the mixture as liquefier and/or Suitable filler systems such as just like partially preconglutinated and partially Swollen ones CaCO, for manufacturing mixtures with a high level of solids that are used with the usual technical adhesive processes concentration and to maintain a mixture with lower viscosity. 0034. Dextrines (also called starch gum or maltodex The utilisation (or possible utilisation) of sodium aluminate trines) are degradable starch products whose molecule size is both in solid and liquid form offers the user a great deal of between those of starch and oligosaccharides. Normally, they freedom in individually developing their own starch glue are in the form of white or bright yellow powders and they are recipe applying the adhesive levels to be achieved. In com mainly extracted from wheat, potato and maize starch by dry parison, borax only has limited water solubility (only 3-5% in heating (>150°C.) or with the effect of acid. In nature, dex hot water) which is why it always has to be worked in solid trine is generated from Such things as bacterium macerans form. This is among the well-known problems in industrial and dextrines also occur by enzymatic decomposition of hygiene and occupational safety. starch by means of amylase (http://de.wikipedia.org/wiki/ 0039. The sodium aluminate preferably has a Na2O to dextrine). Therefore, paper or corrugated cardboard is pre Al2O3 ratio in a range of 1.0-1.5. Furthermore, the starch glue ferred that is manufactured using a starch glue compound free compound free of borax has an alkali milieu with a pH-value of borax and containing one dextrine. This dextrine is a yel of 12.5. The starch glue compound free of borax also prefer low dextrine. ably has solid sodium aluminate before cross-linking with a 0035. The effect of the starch glue compound free ofborax Al2O3 content of 53-55% and with grain size distribution of containing one dextrine consists of a very good cold water 0.1-1 mm in quantities from 1 to 35 weight % (preferably soluble property, a short retention time and a fast increase in 2-10 weight %) with reference to the starch glue compound Viscosity where it is only necessary to use a smaller starch free of borax. Beyond this, with cross-linking, the starch glue cooker (or none at all due to coldwater-soluble property of the compound free of borax preferably has a sodium aluminate dextrine) for manufacturing the adhesives. This is in contrast solution with 10-45 weight % of solids concentration with to starch that allows lower procurement/investment costs, reference to the proportion of the starch glue compound free savings in operating expenditures, energy savings and sim ofborax and 5-25 weight% Al2O3 content as a component of plified and more flexible usage of starch glue composition in the starch glue compound free of borax. A final subject of the production. As already shown, if we compare the aforemen invention is using the starch glue compound free of borax tioned reactions with those of borax and starch, we see a mentioned above for manufacturing paperor corrugated card similar process. This reaction ensures that the starch is con board. Examples 1-3 below describe manufacturing starch Verted into a water-soluble aluminate Salt while cross-linking. glues for the paper processing industry without restricting the This makes it possible to adjust rheology and the optimum invention: processability of the starch glue when manufacturing corru gated cardboard. Example 1 0036 That was in and of itself surprising because of the 0040 Starch glue is manufactured from: fact that NaOH (i.e., a very strong alkali additive) was used. 0041) 300 parts of water However, it is known that NaOH cannot bring about starch 0042 20 parts of native wheat starch cross-linking so that it only regulates the pH-value and acts as 0043 8 parts of solid sodium aluminate with 53/55 weight an alkaline decomposition agent for starch while changing % Al-O, 25 min. Stirring at 48°C., 1,100 rpms the gelatinising point. The alkali sodium silicate with NaOH 0044 600 parts of water is also not Suited to bringing about cross-linking and thus 0045 250 parts of native wheat starch stabilise viscosity without addingborax (refer to U.S. Pat. No. 0046 6 parts of sodium aluminate 53/55 weight% Al-O 6,056,816). 20 min stirring at 30°C. , 1,100 rpms 0037. As per the invention, sodium aluminate can now be 0047. The pH-value was 12.5. added in aqueous form, but also in the Solid form of a starch 0048. The final viscosity of the starch glue: 1,170 mPas water dispersion with thermal decomposition. Solid sodium (Brookfield, LV set of spindles, spindle 3, 30 rpm) aluminate is preferred with an Al-O content of 53-55% and it is used with the usual grain size of 0.1-0.063 mm and Example 2 1.0-0.09 mm or it is used as an aqueous sodium aluminate solution with a 10-45% solids concentration and 5-25% 0049 Starch glue is manufactured from: Al-O content as a component. Sodium aluminate is also 0050 500 parts of water preferred in granulate or powder form in quantities from 1 to 0051 400 parts of yellow dextrine 35 weight%, preferably 2-10%, 25-70° C. warm water where 0052 25 parts of sodium aluminate 53/55 weight % the starch is dissolved, added or dispersed with a starch (or Al-O, 30 min. dispersing at 48°C., 1,100 rpms dextrine) proportion of as much as 45% atro. We observe an 0053. The pH-value was 12.5. US 2015/0233058 A1 Aug. 20, 2015

0054) The final viscosity of the starch glue: 900 mPas 4. Paper or corrugated cardboard in accordance with claim (Brookfield, LV set of spindles, spindle 330 rpm) 1 and characterised by the fact that the sodium aluminate has a Na-O to Al-O ratio in the range of 1.0-1.5. Example 3 5. Paper or corrugated cardboard in accordance with claim 1 and characterised by the fact that the starch glue composi 0055 Starch glue is manufactured from: tion free ofborax has an alkali milieu with a pH-value of 12.5. 0056 500 parts of water 6. Paper or corrugated cardboard in accordance with claim 0057 80 parts of sodium aluminate solution at 19%. Al-O 1 and characterised by the fact that the starch glue composi 30 min. tion free ofborax has a solid sodium aluminate with an Al-O 0058 400 parts of yellow dextrine, dispersing at 48°C., content of 53-55% before chain-linking, with a grain size 1,100 rpms distribution of 0.1-1 mm, in quantities of 1-35 weight%, with 0059. The pH-value was 12.5. reference to the starch glue composition free of borax. 0060. The final viscosity of the starch glue: 950 mPas 7. Paper or corrugated cardboard in accordance with claim (Brookfield, LV set of spindles, spindle 3, 30 rpm) 1 and characterised by the fact that the starch glue composi 1. Paper or corrugated cardboard produced while using a tion free of borax contains a Sodium aluminate solution with starch glue composition free of borax that contains one dex 10-45 weight% proportion of solids when chain-linking with trine where the starch glue composition is chain-linked with reference to the proportion of starch glue composition free of Sodium aluminate in an alkali milieu and characterised by the borax and 5-25 weight% Al-O content as a component in the fact that the quantity of Sodium aluminate is in the range of starch glue composition free of borax. 1-35% atro with reference to the use of dextrine. 8. Using a starch glue composition free of borax for manu 2. Paper or corrugated cardboard in accordance with claim facturing paper or corrugated cardboard in accordance with 1 and characterised by the fact that the sodium aluminate claim 1. added to the starch glue composition has a granulate or pow 9. Paperor corrugated carboardinaccordance with claim 6, der form. characterized in that the Al-O is present in quantities of 2-10 3. Paper or corrugated cardboard in accordance with claim weight% with reference to the starch glue composition free of 1 and characterised by the fact that the dextrine is a yellow borax. dextrine.