WO2013096438A1

WO2013096438A1 - Formulation for the prevention of delamination in starch-based adhesives

Info

Publication number: WO2013096438A1
Application number: PCT/US2012/070604
Authority: WO
Inventors: Mark W. Beltz; Jeffrey BOOKS; Penelope A. Patton; Geoffrey NOBES
Original assignee: Tate And Lyle Ingredients Americas Llc
Priority date: 2011-12-19
Filing date: 2012-12-19
Publication date: 2013-06-27
Also published as: AR089340A1

Abstract

A starch-based adhesive composition particularly suitable for making laminate paperboard articles, having an adhesive component selected from dent dextrins, waxy dextrins, thinned waxy starches, thinned dent starches, modified forms of said starches, esters or ethers of the foregoing, and combinations thereof, and a flexibilizing component selected from monosaccharides, disaccharides, oligosaccharides, low-molecular weight polyols and dimer or and oligomers thereof, high-molecular weight starches, and combinations thereof.

Description

FORMULATION FOR THE PREVENTION OF DELAM I NATION IN STARCH- BASED ADHESIVES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 61/577,408 filed December 19, 2011 which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] This invention relates to starch-based aqueous adhesives particularly suitable for, but not limited to, being foamed and used in the making of paperboard articles.

BACKGROUND OF INVENTION

[0003] Foamed adhesives tend to provide economic and performance benefits over adhesives that are not foamed especially when used in corrugated laminating systems. The use of foamed adhesives is advantageous for multiple reasons. For example, foamed adhesive tends to penetrate porous surfaces less than non-foamed adhesives and thus less adhesive tends to be needed to achieve adequate bonding. Further, because foamed adhesive tends to have a higher viscosity than non-foamed adhesive, it tends to remain on the top portion of the corrugation flutes. Also, for any particular thickness of adhesive, a foamed adhesive contains less water which tends to lessen or eliminate grain raise.

[0004] Synthetic foamable adhesives are known in the art and are typically adequate in performance but they are usually produced from non-renewable materials and present environmental and toxicity concerns. Natural, starch-based foamed adhesives are also known but to date they have not demonstrated

acceptable performance characteristics. For example, known foamed starch-based adhesives tend to be unstable and lose their foamed nature within a few minutes. Additionally, when used to manufacture laminated paperboard articles, they have been susceptible to delamination, relatively inflexible, and subject to score cracking. Thus, a need still exists for starch-based adhesives having one or more of the following properties: foamability, increased foam stability, increased flexibility, and reduced score cracking. SUMMARY OF INVENTION

[0005] In one embodiment, the present invention is directed to a dry adhesive composition that, when used to make a wet adhesive composition that comprises the dry adhesive composition and water, passes delamination testing, the dry adhesive composition comprising:

(a) an adhesive component selected from the group consisting of one or more dextrins, one or more thinned starches, one or more modified thinned starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof, wherein the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise, wherein said RVA Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of the first cooked mixture and water as the remainder, wherein the dry solids consists of about 83% by weight of the adhesive component and about 17% by weight of borax; and

(b) a flexibilizing component selected from the group consisting of one or more monosaccharides, one or more disaccharides, one or more oligosaccharides, one or more low-molecular weight polyols, one or more dimers of said low-molecular weight polyols, one or more oligomers of said low-molecular weight polyols, one or more high- molecular weight starches, and combinations thereof, wherein the one or more high-molecular weight starches have a RVA Viscosity that is in the range of about 600 to about 1600 centipoise, wherein said RVA Viscosity is determined using a second cooked mixture consisting of an amount of the one or more high-molecular weight starches in the range of 17 to 32 percent by weight and water as the remainder.

[0006] In one embodiment, the present invention is directed to a dry adhesive composition that, when used to make a wet adhesive composition that comprises the dry adhesive composition and water, passes delamination testing. The dry adhesive composition comprising:

(a) an adhesive component selected from the group consisting of one or more dextrins, one or more thinned waxy starches, one or more modified thinned waxy starches, one or more thinned dent starches, one or more thinned modified dent starches, one or more esters of the foregoing, one or more ethers of the foregoing, and combinations thereof, wherein the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise, wherein said RVA Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of the first cooked mixture and water as the remainder, wherein the dry solids consists of about 83% by weight of the adhesive component and about 17% by weight of borax; and

[0007] In an embodiment of the foregoing dry adhesive compositions, the adhesive component is at an amount that is in the range of about 50 to about 80% by weight of the dry adhesive composition, and the flexibilizing component is at an amount that is in the range of about 1 to about 15% by weight of the dry adhesive composition. Alternatively, the adhesive component is at an amount that is in the range of about 60 to about 75% by weight of the dry adhesive composition, and the flexibilizing component is at an amount that is in the range of about 2 to about 5% by weight of the dry adhesive composition.

[0008] In an embodiment of any the foregoing dry adhesive compositions, the dry adhesive composition, when used to make a wet adhesive composition that comprises the dry adhesive composition and water, has a set speed that is no greater than about 60 seconds. [0009] In an embodiment of any of the foregoing dry adhesive compositions, the one or more monosaccharides are selected from the group consisting of fructose, dextrose, and combinations thereof; the one or more disaccharides is sucrose; the one or more oligosaccharides are selected from one or more corn syrups that have a dextrose equivalent of no more than about 40; the one or more low-molecular weight polyols are selected from the group ethylene glycol, propylene glycol, glycerol, 1 ,3-propanediol, 1 ,4-butanediol, sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, and combinations thereof; and the one or more high-molecular weight starches are selected from the group consisting of one or more dent corn starches, one or more waxy corn starches, one or more wheat starches, one or more potato starches, one or more tapioca starches, modified forms of the foregoing, and combinations thereof.

[0010] In an embodiment of any of the foregoing dry adhesive compositions, the flexibilizing component is selected from the group consisting of low-molecular weight polyols, high-molecular weight starches, and combinations thereof.

[0011 ] In an embodiment of any of the foregoing dry adhesive compositions, the dry adhesive composition further comprises a viscosity stabilizer component selected from the group consisting of one or more B₂0₃-containing compounds, urea, sodium hydroxide, potassium hydroxide, and combinations thereof. In one such embodiment, the viscosity stabilizer component is one or more B₂O₃-containing compounds and the total amount of B2O3 is in the range of about 0.5 to about 10% by weight of the dry adhesive composition. Alternatively, the total amount of B2O3 is in the range of about 0.75 to about 2% by weight of the dry adhesive composition. In another such embodiment, the viscosity stabilizer component is one or more

B₂0₃-containing compounds selected from the group consisting of borax (sodium tetraborate), sodium tetraborate pentahydrate, anhydrous borax, boric acid, and combinations thereof. In another such an embodiment the one or more

B₂0₃-containing compounds is borax and it is at an amount that is in the range of about 2 to about 20% by weight of the dry adhesive composition. Alternatively, the borax and it is at an amount that is in the range of about 2 to about 5% by weight of the dry adhesive composition.

[0012] In an embodiment of any of the foregoing dry adhesive compositions, the dry adhesive composition further comprises a foaming component at an amount that when the dry adhesive composition is used to make a wet adhesive composition that comprises the dry adhesive composition and water, the wet adhesive composition when subjected to effective aeration undergoes a volume increase that is in the range of about 20 to about 50%. Alternatively, wherein the amount of the foaming component is such that the volume increase is in the range of about 30 to about 40%. In an embodiment of the foregoing dry adhesive compositions, the foaming component is selected from the group consisting of one or more anionic surfactants, one or more cationic surfactants, one or more amphoteric surfactants, one or more non-ionic surfactants, and combinations thereof. In another such embodiment, the one or more anionic surfactants are selected from the group consisting of alkyl sulfonates, alkylaryl sulfonates, alkyl sulfates, sulfates of hydroxyalkanols, alkyl and alkyllauryl disulfonates, sulfonated fatty acids, sulfates and phosphates of polyethoxylated alkanols and alkylphenols, and esters of sulfosuccinic acid, and combinations thereof; the one or more cationic surfactants are selected from the group consisting of alkyl quaternary ammonium salts, alkyl quaternary phosphonium salts, and combinations thereof; and the one or more non- ionic surfactants are selected from the group consisting of addition products of 5-50 moles of ethylene oxide adducted to straight and branched chain alkanols having 6- 22 carbon atoms, alkylphenols, higher fatty acids, higher fatty acid amines, primary or secondary higher alkyl amines and block co-polymers of propylene oxide with ethylene oxide, and combinations thereof. In another such embodiment, the foaming component is sodium lauryl sulfate and it is at an amount that is in the range of about 0.25 to about 5% by weight of the dry adhesive composition. In another such embodiment, the foaming component is sodium linear alkyl benzene sulfonate and it is at an amount that is in the range of about 0.25 to about 5% by weight of the dry adhesive composition.

[0013] In another embodiment, the present invention is directed to a dry adhesive composition comprising:

(a) an adhesive component selected from the group consisting of one or more dextrins, one or more thinned waxy starches, one or more thinned modified dent starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof, wherein the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise, wherein said RVA Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of the first cooked mixture and water as the remainder, wherein the dry solids consists of about 83% by weight of the adhesive component and about 17% by weight of borax, and wherein the adhesive component is at an amount that is in the range of about 50 to about 80% by weight of the dry adhesive composition; and

(b) a flexibilizing component selected from the group consisting of one or more monosaccharides, one or more disaccharides, one or more oligosaccharides, one or more low-molecular weight polyols, one or more dimers of said low-molecular weight polyols, one or more oligomers of said low-molecular weight polyols, one or more high- molecular weight starches, and combinations thereof, wherein the one or more high-molecular weight starches have a RVA Viscosity that is in the range of about 600 to about 1600 centipoise, wherein said RVA Viscosity is determined using a second cooked mixture consisting of an amount of the one or more high-molecular weight starches in the range of 17 to 32 percent by weight and water as the remainder, and wherein the flexibilizing component is at an amount that is in the range of about 1 to about 15% by weight of the dry adhesive composition;

(c) one or more B₂0₃-containing compounds such that total amount of B₂0₃ is in the range of about 0.5 to about 10% by weight of the dry adhesive composition; and

(d) an effective amount of a foaming component.

[0014] In a further embodiment, the present invention is directed to a wet adhesive composition comprising water and any of the above-described dry adhesive compositions.

[0015] In an embodiment of the foregoing wet adhesive composition, the water is at a concentration that is in the range of about 30 to about 90% by weight of the wet adhesive composition. Alternatively, the water is at a concentration that is in the range of about 50 to about 80% by weight of the wet adhesive composition.

[0016] In an embodiment of the foregoing wet adhesive compositions, the wet adhesive composition is foamed.

[0017] In yet another embodiment, the present invention is directed to a method of making a wet adhesive composition comprising mixing water and any one the above-described dry adhesive compositions while heating the mixture at one or more temperatures in the range of about 80 to about 95 °C for a period of time in the range of about 20 to about 60 minutes, wherein the dry adhesive composition is at an amount that is the range of about 25 to about 50% by weight of the wet adhesive composition.

[0018] In an embodiment of the foregoing method of making a wet adhesive composition, the mixture is heated to a temperature of about 90 °C for about 30 minutes.

[0019] In an embodiment of the foregoing methods of making a wet adhesive composition, the method further comprises aerating the wet adhesive composition so that the wet adhesive composition is foamed.

[0020] In still another embodiment, the present invention is directed to a paperboard article comprising a flatstock component, a corrugated component, and a cured wet adhesive composition (as described above) securing the flatstock component to the corrugated component.

[0021] In another embodiment, the present invention is directed to a method of making a paperboard article, the method comprising:

(a) applying a wet adhesive composition (as described above) to a

flatstock component, a corrugated component, or both the flatstock component and the corrugated component;

(b) contacting the flatstock component and the corrugated component such that applied wet adhesive is therebetween; and

(c) curing the applied wet adhesive to secure the flatstock component to the corrugated component thereby making the paperboard article.

[0022] In an embodiment of the foregoing method of making a paperboard article, the adhesive composition is applied at a thickness in the range of about 0.025 to about 0.15 mm.

DETAILED DESCRIPTION OF INVENTION

[0023] The present invention is directed to a starch-based adhesive composition, wherein the adhesive composition may be formulated as a dry adhesive composition comprising an adhesive component and flexibilizing

component. Further, said dry adhesive composition may be mixed with water to form a wet adhesive composition. In certain embodiments, the dry adhesive composition and/or the wet adhesive composition may further comprise a foaming component and/or a viscosity stabilizing component. Additionally, certain

embodiments of the adhesive compositions of the present invention are particularly suitable for being used in the production of paperboard articles, wherein a wet adhesive composition is used to secure a flatstock component to a corrugated component.

[0024] As set forth above, the adhesive composition of the present invention comprises an adhesive component. Also set forth above, the adhesive composition of the present invention is starch-based, that is to say, without being held to a particular theory, it is believed that the adhesive functionality of the composition is provided by one or more types of starch (which may be from a variety of sources such as potato, tapioca, wheat, corn, etc). In the development of a starch-based, foamable adhesive particularly suitable for attaching a printed lithograph top sheet onto corrugated flutes, it was found that formulations containing dextrins as the primary adhesive component had set speeds that were short enough and viscosities low enough to be commercially viable for making laminated paperboard articles. Although these early dextrin-based adhesives with foaming agents were formulated to achieve many properties similar to that of PVA- and EVA-based adhesives, it was discovered that when cured they were brittle and paperboard articles manufactured therewith were susceptible to delamination. Specifically, the delamination observed was the separation of the flat stock or top sheet from the flutes of the corrugated paperboard that occurred when the assembly bent or folded.

[0025] To overcome these problems, glycerol, a known natural plasticizer, was used at amounts previously known to impart flexibility to dextrin-based adhesives (e.g. >30% by weight of dextrin). Although increasing the flexibility, the addition of glycerol at these amounts caused unacceptably slow set times and paperboard articles made therewith still tended to be susceptible to delamination.

[0026] Additional experiments and development work was performed and it was unexpectedly discovered that adhesive compositions with adequate flexibility, acceptable short set times, and resistance to delamination may be made by combining a starch-based adhesive component with (a) higher molecular weight starches and/or (b) glycols at levels much lower than previously believed to be effective (e.g., no more than about 10% by weight of the dry adhesive composition or even less than about 5% by weight of the dry adhesive composition).

[0027] Thus, it has been discovered that by selecting appropriate compounds and appropriate amounts thereof for the adhesive component and the flexibilizing component of the adhesive composition of the present invention, certain

embodiments thereof may be formulated that have one or more of the following characteristics with respect to starch-based adhesives previously known in the art: if foamed, increased foam stability, increased flexibility, and reduced score cracking. Additionally, in certain embodiments, the adhesive composition of the present invention may have performance properties similar to that of conventional polyvinyl acetate (PVA) adhesives and ethylene-vinyl acetate co-polymer (EVA) adhesives. Examples of these performance requirements include viscosity, viscosity stability, foaming ability, set speed, score cracking, and delamination.

[0028] The specifics of the various constituents of the adhesive compositions of the present invention are set forth in greater detail below.

[0029] As used herein the property or term referred to herein as "RVA

Viscosity" is a viscosity of the disclosed or described fluid (composition, liquid, slurry, suspension, or solution) determined (measured or quantified) using a RVA Super-4 viscometer manufactured by Newport Scientific using the following method:

• initiate stirring of the fluid (e.g., starch slurry) at 160 rpm in the RVA cup and continue stirring at this rate throughout the measurement process;

• heat the fluid to 95 °C over a period of 5 minutes, then hold at 95 °C for 5

minutes, then cool to 35 °C over a period of 2 minutes, then hold at 35 °C for 7 minutes, and then record the viscosity of the fluid while it is at 35 °C.

Adhesive Component

[0030] The adhesive component is selected from the group consisting of one or more dextrins, one or more thinned starches, one or more modified thinned starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof. In an embodiment, the adhesive component is selected from the group consisting of one or more dextrins, one or more thinned waxy starches, one or more modified thinned waxy starches, one or more thinned dent starches, one or more thinned modified dent starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof. The foregoing are selected such that the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise, wherein said RVA Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of dry solids and water as the remainder, wherein the dry solids consists of about 83% by weight of the adhesive component and about 17% by weight of borax. Commercially available examples of suitable dextrins include but are not limited to STADEX^® 10, 15, 27, 65, 67, 77, 79, 82, 90, 92, 94, 123, 124, 125, 126, 128, 132, and 140, which are available from Tate & Lyle Ingredients Americas LLC. It is readily apparent to persons of skill in the art that references to dextrins herein are applicable to, and include dent dextrins (i.e., dextrins made from dent corn starch) and waxy dextrins (i.e., dextrins made from waxy corn starch), and combinations thereof.

[0031] In one embodiment of the present invention, the adhesive component is at an amount that is in the range of about 50 to about 80% by weight of the dry adhesive composition. In another embodiment, the adhesive component is at an amount that is in the range of about 60 to about 75% by weight of the dry adhesive composition.

Flexibilizinq Component

[0032] In one embodiment, the flexibilizing component is selected from the group consisting of one or more monosaccharides, one or more disaccharides, one or more oligosaccharides, one or more low-molecular weight polyols (e.g.,≤ 200 Daltons), one or more dimers of said low-molecular weight polyols, one or more oligomers of said low-molecular weight polyols, one or more high-molecular weight starches (relative to monosaccharides, disaccharides, and oligomers), and combinations thereof. In another embodiment, the flexibilizing component is selected from the group consisting of low-molecular weight polyols, high-molecular weight starches, and combinations thereof.

[0033] In certain embodiments of the present invention, the one or more monosaccharides are selected from the group consisting of fructose, dextrose, and combinations thereof. In certain embodiments, the one or more disaccharides is sucrose. In certain embodiments, the one or more oligosaccharides are selected from one or more corn syrups that have a dextrose equivalent of no more than about

40 or no more than about 35. Experimental results to date indicate that corn syrups having a dextrose equivalent in excess of about 45 tend not to impart flexibility and/or delamination resistance to an adhesive composition of the present invention. Commercially available examples of such oligosaccharides include but are not limited to STALEY^® 200 (a corn syrup with a dextrose equivalent of 24-29) and STALEY^® 300 (a corn syrup with a dextrose equivalent of 33-38), which are available from Tate & Lyle Ingredients Americas LLC. The one or more low-molecular weight polyols, in certain embodiments, are selected from the group ethylene glycol, propylene glycol, glycerol, 1 ,3-propanediol, 1 ,4-butanediol, sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, and combinations thereof.

[0034] As mentioned above, it was unexpected that high-molecular weight starches would impart flexibility and resistance to delamination. These high- molecular weight starches may also be characterized in terms of RVA Viscosity. Specifically, the one or more high-molecular weight starches that may be used in various embodiments of the adhesive composition of the present invention have a RVA Viscosity in the range of about 600 to about 1600 centipoise, wherein said RVA Viscosity is determined using a second cooked mixture consisting of an amount of the one or more high-molecular weight starches in the range of 17 to 32 percent by weight (e.g., 27% by weight) and water as the remainder.

[0035] In certain embodiments, the one or more high-molecular weight starches are selected from the group consisting of one or more dent corn starches, one or more waxy corn starches, one or more wheat starches, one or more potato starches, one or more tapioca starches, modified forms of the foregoing, and combinations thereof. Stated another way, suitable starches include raw and/or carrier starches, which may be modified to contain a functional group such as a cationic, anionic, non-ionic or hydrophobic substituent. Methods for modifying starch are well known in the art. See, e.g., U.S. Pat. Nos. 2,661 ,349, 5,672,699, "Starch: Chemistry and Technology", second edition, edited by R. L. Whistler et al., 1988, pp. 341-343 and "Modified Starches: Properties and Uses", edited by O. Wurzburg, 1986, Chapter 9, pp. 131-147.

[0036] Commercially available examples of suitable high-molecular weight starches include but are not limited to ECLIPSE^® N (low conversion, white dextrin, low cold water solubles), ECLIPSE^® G (acid modified corn starch), STASIZE^® 100 (acid-thinned, octenyl succinated waxy starch), ETHYLEX^® 2005 (acid-thinned hydroxy ethylated starch), and ETHYLEX 2015 (acid-thinned hydroxy ethylated starch), each of which is available from Tate & Lyle Ingredients Americas LLC.

[0037] In one embodiment of the present invention, the flexibilizing component is at an amount that is in the range of about 1 to about 15% by weight of the dry adhesive composition. In another embodiment, the flexibilizing component is at an amount that is in the range of about 2 to about 5% by weight of the dry adhesive composition. It is to be noted, that for embodiments in which the flexibilizing component comprises one or more low-molecular weight polyols, experimental results to date indicate that as the amount of low-molecular weight polyols exceeds about 5% by weight of the dry adhesive composition, the set speed of adhesive tends to increase and if the amount exceeds about 10% by weight of the dry adhesive composition the set speed may become so long as to render the adhesive composition unsuitable for commercial paperboard lamination operations.

Wet Adhesive Composition

[0038] As mentioned above, the above-described dry adhesive composition may be mixed with water to form a wet adhesive composition. The method of making a wet adhesive composition typically comprises mixing water and a dry adhesive composition. Further, it is typical for the mixing operation to comprise maintaining the mixture at one or more temperatures in the range of about 80 to about 95 °C for a period of time in the range of about 20 to about 60 minutes. In one embodiment, the mixture is heated to a temperature of about 90 °C for about 30 minutes. Typically, the dry adhesive composition is at an amount that is in the range of about 25 to about 50% by weight of the wet adhesive composition and the amount of water in the wet adhesive composition is in the range of about 30 to about 90% by weight of the wet adhesive composition. In another embodiment, the water is at a concentration that is in the range of about 50 to about 80% by weight of the wet adhesive composition.

Delamination

[0039] Advantageously, the above-described dry adhesive composition, when used to make a wet adhesive composition that comprises the dry adhesive

composition and water, passes delamination testing. As used herein, the term "passes delamination testing" means that when an adhesive is subjected to the delamination test set forth in the Examples, below, no delamination, no fiber pick, and no cracking is observed.

Set Speed

[0040] As mentioned above, certain embodiments of the present invention are adhesive compositions that are particularly suitable with commercial paperboard lamination operations, which typically require the adhesive composition to set relatively quickly (e.g., less than about 90 seconds or 60 seconds, or even more quickly). Additionally, certain embodiments of the dry adhesive composition, when used to make a wet adhesive composition that comprises the dry adhesive

composition and water, have a set speed that is no greater than about 60 seconds. The set speeds of embodiments of the adhesive composition of the present invention are determined according to a modified form of a procedure reported in TAPPI Monograph number 35 "Testing of Adhesives" edited by Gregory Meese, Mack Printing Company, Easton, PA, 1974, which is set forth in detail in the Examples, below.

Viscosity Stabilizer Component

[0041] In addition to the foregoing components, the dry and wet adhesive compositions of the present invention may further comprise a viscosity stabilizer component in order for the viscosity of a wet adhesive composition to remain relatively stable from the point of being prepared until it may be used in a commercial operation. Those periods can be quite lengthy and may range from one week to several months (e.g., three months or longer).

[0042] If present, the viscosity stabilizer component is selected from the group consisting of one or more B20₃-containing compounds, urea, sodium hydroxide, potassium hydroxide, and combinations thereof. In one embodiment, the one or more B₂0₃-containing compounds are selected from the group consisting of borax (sodium tetraborate), sodium tetraborate pentahydrate, anhydrous borax, boric acid, and combinations thereof.

[0043] In an embodiment, the amount of the viscosity stabilizer component is such that when the dry adhesive composition is used to make a wet adhesive composition that comprises the dry adhesive composition and water, the wet adhesive composition has a viscosity that is measured when the wet adhesive composition is prepared and that is measured about one week after the wet adhesive composition is prepared and the difference between the prepared viscosity and the one-week viscosity is no greater than about 100% of the prepared viscosity, wherein the viscosity of the wet adhesive composition is measured, upon being stirred and at about 22 °C, using, for example, a BROOKFIELD Digital Viscometer, model RVTDV II, at 20 rpm.

[0044] In another embodiment, the amount of the viscosity stabilizer component is such that when the dry adhesive composition is used to make a wet adhesive composition that comprises the dry adhesive composition and water, the wet adhesive composition has a viscosity that is measured when the wet adhesive composition is prepared and that is measured at about six weeks after the wet adhesive composition is prepared which is no greater than about 10,000 centipoise when measured at about 22 °C without being stirred prior to conducting the viscosity measurement using, for example, a BROOKFIELD digital viscometer, model RVTDV II, at 20 rpm.

[0045] In another embodiment, the amount of the viscosity stabilizer component is such that when the dry adhesive composition is used to make a wet adhesive composition that comprises the dry adhesive composition and water, the wet adhesive composition has a viscosity that is measured when the wet adhesive composition is prepared and that is measured at about three months after the wet adhesive composition is prepared and the difference between the prepared viscosity and three-month viscosity is no greater than about 500% of the prepared viscosity.

[0046] In one embodiment, the viscosity stabilizer component is one or more B2O3-containing compounds and the total amount of B2O3 is in the range of about 0.5 to about 10% by weight of the dry adhesive composition. In another

embodiment, the stabilizer component is one or more B2O3-containing compounds and the total amount of B2O3 is in the range of about 0.75 to about 2% by weight of the dry adhesive composition. In yet another embodiment, the one or more

B2O3-containing compounds is borax and it is at an amount that is in the range of about 2 to about 20% by weight of the dry adhesive composition. In still another embodiment, the one or more B₂O3-containing compounds is borax and it is at an amount that is in the range of about 2 to about 5% by weight of the dry adhesive composition. Foaming Component

[0047] In addition to the foregoing components, the dry and wet adhesive compositions of the present invention may further comprise a foaming component in order for a wet adhesive composition to be foamable. Typically, foaming is achieved by aerating a wet adhesive composition that comprises a foaming component at an amount that when the dry adhesive composition is used to make a wet adhesive composition that comprises the dry adhesive composition and water, the wet adhesive composition when subjected to effective aeration undergoes a volume increase that is in the range of about 20 to about 50%. In one embodiment, the amount of the foaming component is such that the volume increase is in the range of about 30 to about 40%.

[0048] If present, the foaming component is selected from the group

consisting of one or more anionic surfactants, one or more cationic surfactants, one or more amphoteric surfactants, one or more non-ionic surfactants, and

combinations thereof. The one or more anionic surfactants may be selected from the group consisting of alkyi sulfonates, alkylaryl sulfonates, alkyi sulfates, sulfates of hydroxyalkanols, alkyi and alkyllauryl disulfonates, sulfonated fatty acids, sulfates and phosphates of polyethoxylated alkanols and alkylphenols, and esters of sulfosuccinic acid, and combinations thereof. Commercially available examples of such anionic surfactants include but are not limited to ammonium lauryl sulfate, dioctyl sodium sulfosuccinate, linear alkyi benzene sulfonic acid,

perfluorobutanesulfonic acid, perfluorononanoic acid, potassium lauryl sulfate, soap, soap substitute, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium laureth sulfate, sodium lauryl sarcosinate, sodium linear alkylbenzene sulfonates, sodium myreth sulfate, and sodium stearate. The one or more cationic surfactants may be selected from the group consisting of alkyi quaternary ammonium salts, alkyi quaternary phosphonium salts, and combinations thereof. Commercially available cationic surfactants include but are not limited to benzalkonium chloride,

benzethonium chloride, bronidox, cetrimonium bromide, cetrimonium chloride, dimethyldioctadecylammonium chloride, and tetramethylammonium hydroxide. The one or more non-ionic surfactants may be selected from the group consisting of addition products of 5-50 moles of ethylene oxide adducted to straight and branched chain alkanols having 6-22 carbon atoms, alkylphenols, higher fatty acids, higher fatty acid amines, primary or secondary higher alkyi amines and block co-polymers of propylene oxide with ethylene oxide, and combinations thereof. Commercially available examples of such non-ionic surfactants include but are not limited to cetyl alcohol, cocamide DEA, cocamide MEA, decyl glucoside, isoceteth-20, lauryl glucoside, NONIDET P-40, nonoxynol-9, nonoxynols, octaethylene glycol

monododecyl ether, poloxamer, polyglycerol, polysorbates, sorbitan monostearate, stearyl alcohol, and TRITON X.

[0049] In one embodiment, the foaming component is sodium lauryl sulfate and it is at an amount that is in the range of about 0.25 to about 5% by weight of the dry adhesive composition. In another embodiment, the foaming component is sodium linear alkyl benzene sulfonate and it is at an amount that is in the range of about 0.25 to about 5% by weight of the dry adhesive composition.

[0050] One embodiment of the present invention is directed to a dry adhesive composition and/or a wet adhesive composition comprising the dry adhesive composition and water in which the dry adhesive comprises: an adhesive

component, a flexibilizing component, a viscosity stabilizing, and a foaming component. In another embodiment comprising all of the foregoing constituents, the adhesive component selected from the group consisting of one or more dent dextrins, one or more waxy dextrins, one or more thinned waxy starches, one or more thinned modified dent starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof, wherein the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise at about 25 °C, wherein said RVA Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of dry solids and water as the remainder, wherein the dry solids consists of about 83% by weight adhesive component and about 17% by weight borax, and the cooking consists of heating for about 4 minutes at about 95 °C while stirring at about 160 rpm and then cooling to 50 °C, and wherein the adhesive component is at an amount that is in the range of about 50 to about 80% by weight of the dry adhesive composition. In said embodiment, the flexibilizing component selected from the group consisting of one or more monosaccharides, one or more disaccharides, one or more oligosaccharides, one or more low-molecular weight polyols, one or more dimers of said low-molecular weight polyols, one or more oligomers of said low-molecular weight polyols, one or more high-molecular weight starches, and combinations thereof, wherein the one or more high-molecular weight starches have a RVA Viscosity that is either (i) in the range of about 600 to about 1600 centipoise at about 25 °C, wherein said RVA Viscosity is determined using a second cooked mixture consisting of about 27% by weight of high-molecular weight starches and water as the remainder, and the cooking consists of heating for about 4 minutes at about 95 °C and about 160 rpm and then cooling to 50 °C, or (ii) in the range of about 600 to about 1400 centipoise at about 65 °C, wherein said RVA Viscosity is determined using a third cooked mixture consisting of about 20% by weight of high-molecular weight starches and water as the remainder, and the cooking consists of heating for about 4 minutes at about 95 °C and about 160 rpm and then cooling to 50 °C, and wherein the flexibilizing component is at an amount that is in the range of about 1 to about 15% by weight of the dry adhesive

composition. In said embodiment, the viscosity stabilizing component is one or more B₂0₃-containing compounds such that total amount of B₂0₃ is in the range of about 0.5 to about 10% by weight of the dry adhesive composition. Preferably, the amount of the adhesive component is in the range of about 60 to about 75% by weight of the dry adhesive composition; the amount of the flexibilizing component is in the range of about 2 to about 5% by weight of the dry adhesive composition; the total amount of B₂0₃ is in the range of about 0.75 to about 2% by weight of the dry adhesive composition, and the foaming component is at an effective amount.

Making of Paperboard Articles

[0051] As mentioned above, the adhesive compositions of the present invention may be formulated and processed to be suitable for making laminated paperboard articles in which a lamination machine glues a flatstock component and a corrugated component together. This is typically accomplished by applying wet adhesive composition to the flutes and applying the flatstock component thereto.

That said, the adhesive may be applied to a flatstock component, a corrugated component, or both. The flatstock component may be a lithographed top sheet. In such operations, it is typically preferred for wet adhesive compositions to be foamed to increase the viscosity, so it adheres to the top of the flutes better without flowing into the valleys, less adhesive overall is used and less applied adhesive is "wasted" by not providing adhesive functionality. Regardless to which component(s) a wet adhesive composition is applied, the flatstock component and the corrugated component are contacted such that applied wet adhesive is therebetween. Typically, the total thickness of the wet adhesive composition applied to one or both of the components is in the range of about 0.025 to about 0.15 mm. The applied wet adhesive is cured to secure the flatstock component to the corrugated component thereby making the paperboard article.

EXAMPLES

General Procedures

Delamination Test

[0052] The following equipment and materials were used to conduct the delamination test:

1. a lithograph top sheet cut into 4 inch x 4 inch (~ 10 cm x 10 cm) squares;

2. a single faced corrugation cut into 4 inch x 4 inch (~ 10 cm x 10 cm) squares;

3. a 7.5 lb (~ 3.4 kg ) weight; and

4. a timer.

The following procedure is performed to conduct the delamination test:

1. deposit a 4 mil (~ 0.1 mm) film of a wet adhesive composition on to the tips of the single faced corrugation;

2. place the lithographed top sheet on the flute tips and apply as much

pressure as possible without crushing the flutes for 10 seconds.

3. apply the 7.5 lbs. (~ 3.4 kg ) weight to the surface of the lithographs top sheet for 1 minute;

4. allow each laminated paperboard sample to condition for 24 hours in a temperature and humidity controlled room set at a temperature of 72 °F (~ 22 °C) and a relative humidity of 50%;

5. bend the same sample 90° perpendicular to the length of the flutes

forming a third fold line and check for delamination and cracking along the third fold line; and

6. bend the same sample 180° perpendicular to the length of the flutes

forming a fourth fold line and check for delamination and cracking along the fourth fold line. Set Speed Test

[0053] The following equipment and materials were used to conduct the set speed test:

1. 50# brown Kraft paper, 6 inches (~ 15 cm) wide;

2. a 1.5 mil (~ 0.04 mm) bird applicator with 2 inch (~5 cm) gate;

3. a clipboard, longer and wider than paper stock;

4. a hand roller; and

5. a time that reads seconds.

The following procedure is performed to conduct the set speed test:

1. cut two 15 inches (~ 38 cm) long sheets of the Kraft paper;

2. make 1" (~ 2.54 cm) wide cuts 5 inches long into one of the 15 inch

pieces of paper;

3. place the paper with the 1 inch strips on top of the other piece of Kraft paper and clip both to the clipboard;

4. fold the strip sheet up and back thereby exposing the second sheet of Kraft paper

5. place a piece of paper towel underneath and to the far right of the Kraft paper to catch excess adhesive when drawdown is made;

6. set the timer to zero;

7. place the bird applicator (with adhesive placed at the opening of the

applicator), centered on the paper, to the far left on top of the bottom piece of Kraft paper;

8. draw the adhesive down across the paper (excess adhesive will be

caught by the paper towel);

9. unfold the strip sheet over top of adhesive film and immediately use the roller to compress bond with three swipes of the roller (two down the cut strips and one down the length) and then immediately start the timer; and

10. at evenly spaced time intervals, slowly pull up a 1 inch section of the paper and note the time each section was pulled until all the sections are pulled; and

11. examine the amount of fiber tear at each time interval and determine the set speed which corresponds to the time at which the earliest such pulled section exhibits a consistent 100% fiber tear. Example 1

[0054] Adhesive formulations were prepared by mixing the reactants together in the percentages listed in Table 1, below.

Table 1

STADEX 15 is the adhesive component and it is a white dextrin from dent corn starch that is commercially available from Tate & Lyle Ingredients Americas LLC; SLS is sodium lauryl sulfate included as a foaming component; borax is included as a viscosity stabilizing component; glycerol is included as a flexibilizing component; and ETHYLEX^®2015 is included as a flexibility component and it is a high-molecular weight hydroxyethylated dent corn starch.

[0055] The formulations were cooked for 30 minutes in a water bath maintained at about 190 °F (~88 °C) with stirring. The samples were then cooled to about 70 °F (~21 °C). Their viscosities were adjusted to between 1750-2000 cps using a BROOKFIELD digital viscometer, model RVTDV II, with a #3 spindle at 20 rpm by adding tap water. The formulations were then subjected to the above- described tests for delamination and set speed and the results are set forth in Table 2, below. Table 2

[0056] The results indicate that formulation 1 had a relatively short set speed but delaminated when bent at a 90° angle. The addition of either glycerol, starch, or both eliminated the delamination with little or no effect on set speed. The results also indicate that as the amount of glycerol was increased from about 2 to about 20%, the set speed increased from about 50 seconds to greater than 300 seconds. Further, it was observed that at a glycerol content of 7.7% delamination started to occur in the samples. As the amount of ETHYLEX^®2015 was increased from about 3.7 to 11.8%, the set times increased from about 40 to about 110 seconds. The adhesive composition containing more than 6% ETHYLEX^®2015 would have a set time exceeding 60 seconds. Further, delamination was observed in the samples containing more than 6% ETHYLEX^®2015.

Example 2

[0057] Additional formulations were tested in accordance with the foregoing, wherein the formulations are set forth in Table 3, below, and results are set forth in Table 4, below.

Table 3

Table 4

Example 3

[0058] Additional formulations without SLS were tested in accordance with the foregoing, wherein the formulations are set forth in Table 5, below, and results are set forth in Table 6, below.

Table 5

Table 6

[0059] Having illustrated and described the principles of the present invention, it should be apparent to persons skilled in the art that the invention can be modified in arrangement and detail without departing from such principles.

[0060] Although the materials and methods of this invention have been described in terms of various embodiments and illustrative examples, it will be apparent to those of skill in the art that variations can be applied to the materials and methods described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

[0061] As used herein, "about" will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, "about" will mean up to plus or minus 10% of the particular term.

[0062] All ranges discussed can and do necessarily also describe all subranges therein for all purposes and that all such subranges are part this invention. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves (e.g., a lower half and upper half), thirds, quarters, tenths, etc.

Claims

CLAIMS What is claimed is:

1. A dry adhesive composition that, when used to make a wet adhesive composition that comprises the dry adhesive composition and water, passes delamination testing, the dry adhesive composition comprising:

2. A dry adhesive composition that, when used to make a wet adhesive composition that comprises the dry adhesive composition and water, passes delamination testing, the dry adhesive composition comprising: (a) an adhesive component selected from the group consisting of one or more dextrins, one or more thinned waxy starches, one or more modified thinned waxy starches, one or more thinned dent starches, one or more thinned modified dent starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof, wherein the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise, wherein said RVA Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of the first cooked mixture and water as the remainder, wherein the dry solids consists of about 83% by weight of the adhesive component and about 17% by weight of borax; and

3. The dry adhesive composition of claim 1 or claim 2, wherein the adhesive component is at an amount that is in the range of about 50 to about 80% by weight of the dry adhesive composition, and the flexibilizing component is at an amount that is in the range of about 1 to about 15% by weight of the dry adhesive composition.

4. The dry adhesive composition of claim 1 or claim 2, wherein the adhesive component is at an amount that is in the range of about 60 to about 75% by weight of the dry adhesive composition, and the flexibilizing component is at an amount that is in the range of about 2 to about 5% by weight of the dry adhesive composition.

5. The dry adhesive composition of any one of claims 1-4, wherein the dry adhesive composition, when used to make a wet adhesive composition that comprises the dry adhesive composition and water, has a set speed that is no greater than about 60 seconds.

6. The dry adhesive composition of any one of claims 1-5, wherein:

the one or more monosaccharides are selected from the group consisting of fructose, dextrose, and combinations thereof;

the one or more disaccharides is sucrose;

the one or more oligosaccharides are selected from one or more corn syrups that have a dextrose equivalent of no more than about 40;

the one or more low-molecular weight polyols are selected from the group ethylene glycol, propylene glycol, glycerol, 1 ,3-propanediol, 1 ,4-butanediol, sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, and combinations thereof; and

the one or more high-molecular weight starches are selected from the group consisting of one or more dent corn starches, one or more waxy corn starches, one or more wheat starches, one or more potato starches, one or more tapioca starches, modified forms of the foregoing, and combinations thereof.

7. The dry adhesive of any one of claims 1-6, wherein the flexibilizing component is selected from the group consisting of low-molecular weight polyols, high-molecular weight starches, and combinations thereof.

8. The dry adhesive composition of any one of claims 1-7 further comprising a viscosity stabilizer component selected from the group consisting of one or more B₂0₃-containing compounds, urea, sodium hydroxide, potassium hydroxide, and combinations thereof.

9. The dry adhesive composition of claim 8, wherein the viscosity stabilizer component is one or more B₂0₃-containing compounds and the total amount of B₂0₃ is in the range of about 0.5 to about 10% by weight of the dry adhesive composition.

10. The dry adhesive composition of claim 8, wherein the viscosity stabilizer component is one or more B20₃-containing compounds and the total amount of B2O3 is in the range of about 0.75 to about 2% by weight of the dry adhesive composition.

11. The dry adhesive composition of claim 7, wherein the viscosity stabilizer component is one or more B20₃-containing compounds selected from the group consisting of borax (sodium tetraborate), sodium tetraborate pentahydrate, anhydrous borax, boric acid, and combinations thereof.

12. The dry adhesive composition of claim 11 , wherein the one or more B203-containing compounds is borax and it is at an amount that is in the range of about 2 to about 20% by weight of the dry adhesive composition.

13. The dry adhesive composition of claim 11 , wherein the one or more B20₃-containing compounds is borax and it is at an amount that is in the range of about 2 to about 5% by weight of the dry adhesive composition.

14. The dry adhesive composition of any one of claims 1-13 further comprising a foaming component at an amount that when the dry adhesive composition is used to make a wet adhesive composition that comprises the dry adhesive composition and water, the wet adhesive composition when subjected to effective aeration undergoes a volume increase that is in the range of about 20 to about 50%.

15. The dry adhesive composition of claim 14, wherein the amount of the foaming component is such that the volume increase is in the range of about 30 to about 40%.

16. The dry adhesive composition of any one of claims 14 and 15, wherein the foaming component is selected from the group consisting of one or more anionic surfactants, one or more cationic surfactants, one or more amphoteric surfactants, one or more non-ionic surfactants, and combinations thereof.

17. The dry adhesive composition of claim 16, wherein:

the one or more anionic surfactants are selected from the group consisting of alkyl sulfonates, alkylaryl sulfonates, alkyl sulfates, sulfates of hydroxyalkanols, alkyl and alkyllauryl disulfonates, sulfonated fatty acids, sulfates and phosphates of polyethoxylated alkanols and alkylphenols, and esters of sulfosuccinic acid, and combinations thereof;

the one or more cationic surfactants are selected from the group consisting of alkyl quaternary ammonium salts, alkyl quaternary phosphonium salts, and

combinations thereof; and

the one or more non-ionic surfactants are selected from the group consisting of addition products of 5-50 moles of ethylene oxide adducted to straight and branched chain alkanols having 6-22 carbon atoms, alkylphenols, higher fatty acids, higher fatty acid amines, primary or secondary higher alkyl amines and block copolymers of propylene oxide with ethylene oxide, and combinations thereof.

18. The dry adhesive composition of claim 14, wherein the foaming component is sodium lauryl sulfate and it is at an amount that is in the range of about 0.25 to about 5% by weight of the dry adhesive composition.

19. The dry adhesive composition of claim 14, wherein the foaming component is sodium linear alkyl benzene sulfonate and it is at an amount that is in the range of about 0.25 to about 5% by weight of the dry adhesive composition.

20. A dry adhesive composition comprising:

(a) an adhesive component selected from the group consisting of one or more dextrins, one or more thinned waxy starches, one or more thinned modified dent starches, one or more esters of the foregoing, one or more ethers or the foregoing, and combinations thereof, wherein the adhesive component has a RVA Viscosity that is in the range of about 400 to about 1500 centipoise at about 25 °C, wherein said RVA

Viscosity is determined using a first cooked mixture consisting of dry solids at an amount in the range of about 25 to about 38% by weight of the first cooked mixture and water as the remainder, wherein the dry solids consists of about 83% by weight of the adhesive component and about 17% by weight of borax, and wherein the adhesive component is at an amount that is in the range of about 50 to about 80% by weight of the dry adhesive composition; and

(b) a flexibilizing component selected from the group consisting of one or more monosaccharides, one or more disaccharides, one or more oligosaccharides, one or more low-molecular weight polyols, one or more dimers of said low-molecular weight polyols, one or more oligomers of said low-molecular weight polyols, one or more high- molecular weight starches, and combinations thereof, wherein the one or more high-molecular weight starches have a RVA Viscosity that is in the range of about 600 to about 1600 centipoise at about 25 °C, wherein said RVA Viscosity is determined using a second cooked mixture consisting of an amount of the one or more high-molecular weight starches in the range of 17 to 32 percent by weight and water as the remainder, and wherein the flexibilizing component is at an amount that is in the range of about 1 to about 15% by weight of the dry adhesive composition;

(d) an effective amount of a foaming component.

21. The dry adhesive composition of claim 20, wherein:

the amount of the adhesive component is in the range of about 60 to about 75% by weight of the dry adhesive composition;

the amount of the flexibilizing component is in the range of about 2 to about 5% by weight of the dry adhesive composition; and

the total amount of B₂0₃ is in the range of about 0.75 to about 2% by weight of the dry adhesive composition.

22. A wet adhesive composition comprising water and any one of the dry adhesive compositions of claims 2-21.

23. The wet adhesive composition of claim 22, wherein the water is at a concentration that is in the range of about 30 to about 90% by weight of the wet adhesive composition.

24. The wet adhesive composition of claim 22, wherein the water is at a concentration that is in the range of about 50 to about 80% by weight of the wet adhesive composition.

25. The wet adhesive composition of any one of claims 22-24, wherein the wet adhesive composition is foamed.

26. A method of making a wet adhesive composition of any one of claims 22-25, the method comprising mixing water and any one of the dry adhesive compositions of claims 2-21 while heating the mixture at one or more temperatures in the range of about 80 to about 95 °C for a period of time in the range of about 20 to about 60 minutes, wherein the dry adhesive composition is at an amount that is the range of about 25 to about 50% by weight of the wet adhesive composition.

27. The method of claim 26 wherein the mixture is heated to a temperature of about 90 °C for about 30 minutes.

28. The method of claim 26 or claim 27, wherein the method further comprises aerating the wet adhesive composition so that the wet adhesive composition is foamed.

29. A paperboard article comprising a flatstock component, a corrugated component, and a cured wet adhesive composition of any one of claims 22-25 securing the flatstock component to the corrugated component.

30. A method of making a paperboard article, the method comprising: (a) applying a wet adhesive composition of any one of claims 22-25 to a flatstock component, a corrugated component, or both the flatstock component and the corrugated component;

31. The method of claim 30, wherein the adhesive composition is applied at a thickness in the range of about 0.025 to about 0.15 mm.