WO2001010966A1 - Deodorizing adhesive - Google Patents

Abstract

A water-based adhesive includes an adsorption agent or scavenger to eliminate undesirable odors and flavors from the adhesive. The adsorption agent is a crystalline siliceous molecular sieve having a pore diameter greater than 4 Angstroms and having a water adsorption capacity of 10 % or less. The preferred molecular sieve is a hydrophobic zeolite.

Description

DEODORIZING ADHESIVE

BACKGROUND OF THE INVENTION The present invention relates to adhesives, and more particularly to a water-based adhesive containing an adsorption agent or scavenger to eliminate undesirable odors and flavors from the adhesive.

Many of the films, adhesives and other polymeric materials utilized in applications such as food packaging, disposable non-wovens, and the like possess undesirable odors and flavors. These odors and flavors may at times become so offensive that the film, adhesive or other material becomes unsuitable for the desired application. In addition, such odors and flavors may be absorbed by a food product contained within a package resulting in an undesirable off- taste and/ or odors.

A variety of solutions have been proposed for eliminating or at least inhibiting undesirable odors and flavors in such applications. Generally, the solutions proposed are in one of two categories. One approach is to mask the undesirable odors and/ or tastes by adding a substance with a relatively pleasant odor and/ or taste which overpowers the undesirable odor and/or taste with the dominant pleasant odor and/or taste. These types of compounds have been problematic in that they may add their own strong odor and/ or taste which may result in yet a further undesirable odor and/or taste. The second approach is to sequester the undesired odor and/ or taste in a non-volatile form either by chemical reaction, adsorption or absorption on a substance that sorbs the undesirable odor and/ or taste. In this latter category, adsorbents such as zeolites, diatomaceous earth, clays, activated carbons such as activated charcoal or active carbon, silica gel, activated alumina, kieselguhr, Fuller's earth and other clay minerals, either alone or in combination, have been incorporated into certain polymer or copolymer films with varying results.

In the past, zeolites have been used as the adsorbent for air filter elements, and as a component in pet litter to control odors. Also, it has been used in polymer and copolymer films as noted above to control odors and flavors. However, zeolites have not been employed in water-based adhesives since zeolites are known to absorb water. Thus, it was conventionally believed that if zeolites were incorporated with water-based adhesives, one would obtain an undesirable increase in viscosity or thickening of the adhesive and/ or block the pores in the zeolite with water and thereby not permit the pores to be available for adsorption of anything else.

SUMMARY OF THE INVENTION

The object of the present invention is to reduce or eliminate undesirable odors and/ or flavors in water-based adhesives so that certain of such adhesives, not here-to-fore capable of being used, can now be employed for food packaging and disposable non-woven applications as well as other applications. In order to accomplish the above object, the present invention provides an adhesive composition comprising a water- based adhesive, and an adsorption agent. The preferred adsorption agent is a siliceous molecular sieve which is manufactured or subsequently treated to have high hydrophobicity. The preferred molecular sieve is a zeolite having a pore diameter of at least 4 Angstroms, preferably at least 6 Angstroms, and having a water adsorption capacity of less than 10% by weight at 25°C, most preferably less than 6% by weight. Typically, the adsorption agent will comprise at least 0.1-20% by weight of the composition, more preferably at least 0.5% by weight of the composition. However, the amount of adsorbent in the adhesive composition will depend upon various factors including the particular polymer or copolymer used in the adhesive, the films used and the coatings or inks used in the structure. DETAILED DESCRIPTION OF THE INVENTION A water- based adhesive contains an adsorption agent in the form of a siliceous molecular sieve for reducing or eliminating undesirable odors and flavors from adhesives. The preferred molecular sieve is a zeolite having a pore size of at least 4 Angstroms, preferably of at least 6

Angstroms, and manufactured or subsequently treated to have a sorption capacity for water of less than 10% by weight at 25°C, and preferably, less than 6% by weight at 25°C.

In accordance with the present invention, an adhesive may be formulated having the following composition:

Ingredient % Range by Weight

Polymer Emulsion(s) 20 to 99.9 pH adjuster(s) 0 to 5

Defoamer(s) 0 to 5

Biocide(s) 0 to 3

Filler(s) 0 to 80

Stabilizer(s) 0 to 10

Plasticizers 0 to 50

Deionized Water 0 to 50

Zeolite(s) (Molecular Sieves(s)) 0.1 to 20

Resin Dispersions or Emulsions 0 to 80

Other Additives 0 to 25

The components totaling 100% by weight of the water-based adhesive composition. The preferred embodiment of the adhesive composition comprises the following: Ingredient % Range by Weight

Polymer Emulsion(s) 80 to 96 pH adjuster (s) 0.2 to 1.5

Defoamer(s) 0.1 to 0.5

Biocide(s) 0.01 to 0.5

Filler(s) 0.0 to 20.0

Stabilizer(s) 0.0 to 1.0

Plasticizers 0.0 to 10

Deionized Water 0.1 to 7.5

Zeolite(s) (Molecular Sieve(s)) 0.1 to 5.0

Resin Dispersions or Emulsions 0.0 to 5.0

Other additives 0.0 to 2.0

The components totaling 100% by weight of the adhesive composition. The adhesive composition may contain other additives or components which can modify the adhesive properties of, or add adhesive properties to, the above basic adhesive composition. Such components may be those conventionally employed in the art for various purposes in adhesive compositions, such as, for example, dyes, pigments, antioxidants, and the like. When such optional ingredients are employed, their usage is generally in the range or loading level typically utilized in the art for such purposes, as will hereinafter be described.

The odorous compounds suitably treated in the present process can be any organic molecular species having pleasant as well as unpleasant odors as perceived by human beings. Accordingly, since the greatest benefit of odor control involves the elimination of those which are generally unpleasant, it is preferred that the organic compounds treated in the present process are classifiable in one of the following subgeneric classes: (a) saturated or unsaturated aliphatic acids and aldehydes containing a single -COOH or -CHO group and containing less than 12 carbon atoms, such as acetic, propionic, butyric, valeric, isovaleric (alpha- methyl-butyric), caproic and caprylic acids. (b) organic sulfur-containing compounds in which the valence of the sulfur atom is less than 6, especially those in which the valence of sulfur is 2, such as the sulfhydryl compounds, i.e. mercaptans and thiophenols of the general formula R-S-H wherein "R" represents an alkyl or alkenyl group containing from 1 to 8 carbon atoms or a phenyl or substituted phenyl group containing from 6 to 9 carbon atoms; the sulfides of the general formula R-(S)_n-R wherein n has a value of from 1 to 4 and "R" represents the same groups as in the case of the aforesaid sulfhydryl compounds; the thioaldehydes and thioketones of the general formula

S R' — C — R

wherein R' is hydrogen or R, and R is an alkyl or alkenyl group containing from 1 to 8 carbon atoms or a phenyl or substituted phenyl group containing from 6 to 9 carbon atoms; and (c) organic nitrogen-containing compounds in which the valence of the nitrogen atom is 3, such as the aliphatic amines of the general formula R₂NR' wherein R is hydrogen and R' is an alkyl or alkenyl group having from 1 to 6 carbon atoms; and the heterocyclic nitrogen compounds containing an imino group in which the nitrogen atom is a part of the heterocyclic ring, particularly the pyrroles, and especially the pyrroles in which the alpha position is unsubstituted, and the condensed pyrroles which are the indoles, i.e. indole per se and the substituted derivatives thereof.

The siliceous molecular sieves suitably employed in the practice of the invention include the microporous crystalline aluminosilicates, i.e. the zeolitic molecular sieves as well as the so-called silica polymorphs. With respect to the latter compositions, their crystal lattices are ideally formed entirely of SiO₂ tetrahedral units, but the as-synthesized forms commonly contain at least trace amounts of aluminum derived from aluminum impurities in the synthesis reagents. The alumino silicate molecular sieves comprise the large class of well-known crystalline zeolites. These high-silica molecular sieves are either commercially available or are prepared by methods, well-known in the art, involving direct hydrothermal synthesis or involving certain types of crystal lattice dealuminations. Suitable and preferred siliceous molecular sieves are commercially available under the trademark "Abscents" from UOP.

The amount of adsorbent in the polymer or copolymer composition according to the invention will depend upon various factors including the particular copolymer or polymer used. Typically the adsorbent agent will comprise at least 0.1% by weight of the composition, more typically 0.1% to 20% by weight of the composition. The preferred range is 1% to 5% by weight of the adhesive composition.

Suitable siliceous molecular sieves are known in the art, see e.g. UOP's "Abscents" noted above, and have a frame-work of tetrahedral oxide units, in which at least 90% of the tetrahedral oxide units are SiO tetrahedra and have a pore diameter greater than 4.0 Angstroms (preferably at least 6.0 Angstroms) and have a sorption capacity for water of less than 10% by weight at 25°C and 4.6 torr (preferably less than 6% by weight). Preferred such sieves will have a framework S1O2/AI2O3 molar ratio greater than 35, more preferably 200 to 500. While many molecular sieves with framework SiO2/AbO3 molar ratios of greater than about 35 exhibit the requisite degree of hydrophobicity for use in the present invention, some do not. Molecular sieves which cannot be directly synthesized to have both sufficiently high Si/Al and/ or degree of hydrophobicity ratios can be subjected to dealumination techniques, fluorine treatments and the like, which result in zeolite products having the requisite molar ratios and hydrophobicity for use in the adhesives of the present invention.

The water-based adhesive is typically interposed between two or more substrates and functions to bond the substrates together. The adhesive comprises, as a primary ingredient thereof, 20% to 99.9% by weight, preferably 80% to 90% by weight, of a polymer containing one or more monomers which may be polymerized or copolymerized to yield desired adhesive properties. Monomers useful herein include, but are not limited to styrene, methylmethacrylate, vinyl acetate, vinyl chloride, and diphenylmethane diisocyanate. The monomers that can be either homopolymerized or copolymerized to obtain these polymers include but are not limited to:

1. Monomers that produce main chain acyclic carbon polymers such as:

(a) dienes that result in polydienes such as neoprene, poly butadiene, polyisoprene, and others;

(b) alkenes that result in polyalkenes such as polybutene- 1, polybutylethylene, polyethylene, polyisobutylene, polymethylene, polypropylene, and others;

(c) acrylic acid and acrylic acid esters that result in polyacrylics and polyacrylates such as polyacrylic acid, polybenzyl acrylate, polybutyl acrylate, polyethyl acrylate, polycyano acrylates, and others; (d) acrylamides that result in polyacrylamides such as polyacrylamide, polybutylacrylamides, polyisopropylacrylamide, and others;

(e) methacrylic acid and methacrylic acid esters that result in polymethacrylics and polymethacrylates such as polybutylmethacrylate, polyethylmethacrylate, polymethacrylic acid, polymethylmethacrylate, polypropylmethacrylate and others; (f) acrylamides and methacrylamides that result in polyacrylamide and polymethacrylamides such as poly (4- butoxycarbonylphenylmethacrylamide), poly (N-tert- butylmethacrylamide), poly (N-carboxyphenylmethacrylamide), and others;

(g) alpha or beta substituted acrylics or methacrylics that result in polyacrylics and polymethacrylics such as polybutychloroaciylate, polybutylcyanoaciylate, polyethylchloroacrylate, and others; (h) vinyl ethers and vinyl thioethers that result in polyvinylethers and polyvinyl thioethers such as poly butoxye thy lene, polybutylthiothylene, polyethoxyethylene, polymethoxyethylene, polymethylthioethylene, and others;

(i) vinyl alcohol that results in polyvinylalcohols such as polybenzoylethylene, poly (4-chlorobenzoylethylene), polyvinylalcohol, and others;

(j) vinyl halides and vinyl nitriles that result in polyvinylhalides and polyvinylnitriles such as polymethacrylonitrile, polyvinylchloride, and others; (k) vinyl esters that result in polyvinylesters such as polyvinylacetate, polyvinylformate, polycyclopentanoyloxyethylene, polybenzoylethylene, and others;

(1) styrene that result in polystyrenes such as polybutylstyrenes, polychlorostyrenes, polyethylstyrenes, polymethylstyrenes, polystyrene, and others;

(m) other monomers that form polymers such as polybenzylethylene, polyvmylpyridine, polyvinylpyrolidine, and others;

2. Monomers that produce main chain carbocyclic polymers such as: (a) phenylenes that result in polyphenylenes such as poly (2-bromo- l ,4-phenyleneethylene), poly (2,5-dichloro- l ,4- phenyleneethylene), poly (1 ,4-phenyleneethylene), and others;

(b) other monomers that form polymers such as polycyclobutene, poly (1,4-naphthyleneethylene), and others;

3. Monomers that produce main chain heteroatom polymers such as:

(a) polyoxides such as polyoxyethylenes, polyoxymethylene, polyoxypropylene, and others;

(b) polycarbonates, such as poly(oxycarbonyloxy-2-chloro- 1 ,4-phenyleneisopropylidene-3-chloro- 1 ,4-phenylene) , poly(oxycarbonyloxy-2,2,3,3,4,4,5,5-octafluorohexamethylene), poly(oxycarbonyloxy- 1 ,4-phenylenecyclohexylidene- 1 ,4-phenylene) and others;

(c) polyesters, such as poly(ethylene adipate), poly(ethylene terephthalate) , poly(oxyethyleneoxyadipoyl) and others;

(d) polyanhydrides, such as poly(oxycarbonyl- 1 ,4- phenylenehexafluorotrimethylene- 1 ,4-phenylene-carbonyl) , poly(oxycarbonyl- 1 ,4-phenylenepentamethylene- 1 ,4-phenylenecarbonyl) , poly(oxyisophthaloyl), poly(methacrylic anhydride) and others;

(e) polyamides such as poly(imino-5-tert- butylisophthaloyliminomethylene- 1 ,4-phenylenemethylene), poly(iminocarboxyl- 1 ,4-cyclohexylenemethylene) , poly(iminoisophthaloyliminohexamethylene) and any of the numerous nylons known in the art; and others;

(f) polyacetals such as poly(2-ethyl-l,3-dioxa-4,6- cyclohexylenemethylene), poly(vinyl acetal), poly (vinyl butyral) and others; and (g) polypiperazines such as poly(l,4-piperazinediyladipoyl), poly(l,4- piperazinediylcarboxyloxyethyleneoxycarbonyl), poly(l,4- piperazinediylisophthaloyl) and others;

4. Isocyanates such as:

(a) hexamethylene diisocyanate;

(b) isophorone diisocyanate;

(c) trimethylhexamethylene diisocyanate;

(d) hydrogenated 4,4' - diphenylme thane diisocyanate; (e) trans-cyclohexane diisocyanate;

(f) m-tetramethylxylylene diisocyanate;

(g) 4,4'-diphenylmethane diisocyante; (h) 2,4'-diphenylmethane diisocynate; (i) 2,2'-diphenylmethane diisocyanate; (j) mixed 4,4'-diphenylmethane diisocyanate and 2,4'- diphenylme thane diisocyanate;

(k) mixed 4,4'-diphenylmethane diisocyanate and 2,2'- diphenylme thane diisocyanate;

(1) 2,4-toluene diisocyanate; (m) 2,6-toluene diisocyanate;

(n) mixed 2,4-toluene diisocyanate and 2,6-toluene diisocyanate;

(o) p-phenylene diisocyanate;

(p) 4,4'-dibenzyl diisocyanate; (q) 1,5-naphthalene diisocyanate;

(r) tolidene diisocyanate; and

(s) polymeric diphenylmethane diisocyanate.

A more complete listing of the polymers can be found in various polymer reference handbooks, and particularly in Polymer Handbook 2^nd

Edition, John Wiley 8B Sons, 1975 and Polymer Handbook 4^th Edition 1999. The polymers useful in the present compositions include a polymer or copolymer containing one or more monomers previously listed, but preferably is selected from SIS (styrene-isoprene- styrene); SBS (styrene- butadiene-styrene); SEBS (styrene-ethylene-butylene-styrene); EVA (ethylene-vinyl acetate); APAO (amorphous polyalpha olefin); SBR (styrene- butadiene-rubber); (VA) vinyl acetate homopolymer; acrylic polymers and copolymers; as well as styrene acrylic polymers and copolymers. The most preferred amount of polymer or blend of polymers is from about 80% to 99.9% by weight. The tackifying resins which are used in the adhesives of the present invention are those which extend the adhesive properties and improve the specific adhesion of the polymer. The present formulation includes from about 0% to about 80% by weight of a tackifying resin. As used herein, the term "tackifying resin" includes: (a) natural and modified rosin such as, for example, gum rosin, wood rosin, tall-oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin and polymerized resin;

(b) glycerol and pentaerythritol esters of natural and modified rosins, such as, for example, the glycerol ester of pale wood rosin, the glycerol ester of hydrogenated rosin, the glycerol ester of polymerized rosin, the pentaerythritol ester of pale wood rosin, the pentaerythritol ester of hydrogenated rosin, the pentaerythritol ester of tall oil rosin and the phenolic modified pentaerythritol ester of rosin;

(c) polyterpene resins having a softening point, as determined by ASTM method E28-58T, of from about 20°C to 140°C, the latter polyterpene resins generally resulting from the polymerization of terpene hydrocarbons, such as the monoterpene known as pinene, in the presence of Friedel-Crafts catalysts at moderately low temperatures; also included are the hydrogenated polyterpene resins; (d) copolymers and terpolymers of natural terpenes, e.g. styrene/ terpene, α-methyl styreneterpene and vinyl toluene /terpene; (e) phenolic-modified terpene resins such as, for example, the resin product resulting from the condensation, in an acidic medium, of a terpene and a phenol;

(f) aliphatic petroleum hydrocarbon resins having Ring and Ball softening points of from about 10°C to 140°C, the latter resins resulting from the polymerization of monomers consisting primarily of olefins and diolefins; also included are the hydrogenated aliphatic petroleum hydrocarbon resins; examples of such commercially available resins based on a Cs-olefin fraction of this type are "Wingtack 95" and "Wingtack 115" tackifying resins sold by Goodyear Tire and Rubber Company;

(g) aromatic petroleum hydrocarbons and the hydrogenated derivatives thereof;

(h) aliphatic/ aromatic petroleum derived hydrocarbons and the hydrogenated derivatives thereof. Mixtures of two or more of the above described tackifying resins may be required for some formulations.

Commercially available polymerized rosins may be secured from Arizona Chemical Company under the trade designations "Sylvatac 295, RX, R85, 95, and 140," respectively. Additionally, Hercules, Inc. produces a suitable dimerized rosin under the trade designation "Demerex."

Commercially suitable partially hydrogenated rosins may be secured from Hercules, Inc. under the trade designations "Foral AX" and "Stabelite." Finally, partial ester of dibasic modified tall oil rosins may be secured from Arizona Chemical Company under the trade designation "Sylvatec 203," and "Beckacite 4901."

Both water soluble and water insoluble plasticizers can be present in the composition of the present invention either alone or in any desired combination in amounts of about 0% to about 50% by weight in order to provide desired viscosity control without substantially decreasing the adhesive strength or the service temperature of the adhesive. Both liquid and solid plasticizers can be used in the composition of the present invention.

The water soluble plasticizers used herein comprise low molecular weight polyethylene glycols, multifunctional alcohol and the general class of surfactants wherein the molecules contain both a hydrophilic group and a hydrophobic group. The hydrophilic group of the molecule generally consists of, but is not limited to, polyethylene glycol, polypropylene glycol, a mono- or di- hydroxylated amino group, an ethoxylated amino radical, polyalkylene glycol esters of carboxylic group, substituted or unsubstituted glycerol, glucose, sucrose and sorbitan groups. The hydrophobic group of the molecule generally consist of, but is not limited to, a hydrocarbon radical such as, alkylphenol groups, dialkyl phenol groups, or a linear or branched aliphatic radicals. The preferred soluble plasticizers include ethoxylated alkyphenols, ethoxylated fatty acids and ethoxylated fatty alcohol having a HLB value in the range of 8.0-20.0. An ethoxylated alkyphenol with HLB value of 13.5 can be obtained under the trade designation Triton X- 100 from Union Carbide Corporation of Danbury, Connecticut, and water soluble ethoxylated fatty acids, such as polyethylene glycol 600 monolaurate (HLB= 14.6) and polyethylene glycol 1000 dilaurate (HLB=14.2), can be purchased from Stepan Company of Northfield, Illinois under the trade designations of Kessco PEG 600MC and PEG 1000DL, respectively.

A suitable insoluble plasticizer may be selected from the group which includes dipropylene glycol dibenzoate, pentaerythritol tetrabenzoate; polyethylene glycol 400-di-2-ethylhexoate; 2-ethylhexyl diphenyl phosphate; butyl benzyl phthalate, dibutyl phthalate, dioctyl phthalate, various substituted citrates, and glycerates. Suitable dipropylene glycol dibenzoate and pentaerythritol tetrabenzoate may be purchased from Velsicol Chemical Company of Chicago, Illinois under the trade designations "Benzoflex 9-88 and S-552", respectively. Further, a suitable polyethylene glycol 400-di-2-ethylhexoate may be purchased from C.P. Hall Company of Chicago, Illinois under the trade designation "Tegner 809". A suitable 2-ethylhexyl diphenyl phosphate, and a butyl benzyl phthalate may be purchased from Monsanto Industrial Chemical Company of St. Louis, Missouri under the trade designation "Santicizer 141 and 160", respectively.

A suitable plasticizer may be selected from the group which not only includes the usual plasticizing oils, such as mineral oil, but also olefin oligomers and low molecular weight polymers, as well as vegetable and animal oil and derivatives of such oils. The petroleum derived oils which may be employed are relatively high boiling temperature materials containing only a minor proportion of aromatic hydrocarbons. In this regard, the aromatic hydrocarbons should preferably be less than 30% and more particularly less than 15%, by weight, of the oil. Alternately, the oil may be totally non-aromatic. The oligomers may be polypropylenes, polybutenes, hydrogenated polyisoprene, hydrogenated butadiene, or the like having average molecular weights between about 350 and about 10,000. Suitable vegetable and animal oils include glycerol esters of the usual fatty acids and polymerization products thereof. The plasticizer that finds usefulness in the present invention can be any number of different plasticizers but the inventors have discovered that mineral oil such as Kaydol manufactured by Witco, is particularly useful in the present invention. Benzoflex 9-88, a dipropylene glycol dibenzoate manufactured by Velsicol, as also been found to be an appropriate plasticizer. As will be appreciated, plasticizers have typically been employed to lower the viscosity of the overall adhesive composition without substantially decreasing the adhesive strength and/ or the service temperature of the adhesive. The choice of plasticizer can be useful in formulation for specific end uses (such as wet strength core applications). The present invention may include a stabilizer or antioxidant in an amount of from about 0% to 3% by weight, but preferably from about 0.1% to 1%. The stabilizers which are useful in the adhesive compositions of the present invention are incorporated to help protect the polymers noted above, and thereby the total adhesive system, from the effects of thermal and oxidative degradation which normally occurs during the application of the adhesive as well as in the ordinary exposure of the final product to the ambient environment. Such degradation is usually manifested by a deterioration in the appearance, physical properties and performance characteristics of the adhesive. Among the applicable stabilizers or antioxidants are phosphites, thioesters, substituted amines, mercaptobenzimidazole derivatives, hydroquinone derivatives, hindered phenols and multifunctional phenols, such as sulfur and phosphorus- containing phenols. Particularly useful stabilizers or antioxidants are hindered phenols. Hindered phenols are well known to those skilled in the art and may be characterized as phenolic compounds which also contain sterically bulky radicals in close proximity to the phenolic hydroxyl group thereof. Representative hindered phenols include: l ,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxbenzyl) benzene; n-octadecyl-3-(3,5-ditert-butyl-4-hydroxyphenyl) propionate;

4,4'-methylenebis(4-methyl-6-tert butylphenol);

4,4'-thiobis(6-tert-butyl-o-resol); 2, 6-ditert- butylphenol;

6-(4-hydroxyphenoxy)-2,4-bis(n-ocytlthio)- l,3,5-triazine;

2,4,6-tris(4-hydroxy-3,5-di-tert-butylphenoxy)-l,3,5-triazine; di-n-octadecyl-3,5-di-tert-butylbenylphosphonate;

2-(n-octylthio)ethyl-3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa-(3,3,5-di-tert-butyl-4-hydroxy-phenyl) propionate.

An especially preferred antioxidant is Irganox 1010, a tetrakis(methylene(3.5-di-tert-butyl-4-hydroxyhydrocinnamate)methane manufactured by Ciba Geigy.

The performance of these stabilizers may be further enhanced by utilizing, in conjunction therewith; (1) synergists such as, for example, thiodipropionate esters and phosphates; and (2) chelating agents and metal deactivators such as, for example, ethylenediaminetetraacetic acid, salts thereof, and disalicylalpropylenediimine.

Waxes in the composition of the present invention ranging from 0% to 10% are used to reduce the surface tack of the adhesives without appreciably decreasing their adhesive bonding characteristics. These waxes also are used to reduce the blocking of the composition without effecting the temperature performance. Among the useful waxes are:

(1) low molecular weight, that is, 1000-6000, polyethylene having a hardness value, as determined by ASTM method D- 1321 of from about 0.1 to 120 and ASTM softening points of from about 150°F to 250°F.

(2) petroleum waxes such as paraffin wax having a melting point of from about 130°F to 170°F and microcrystalline wax having a melting point of from about 135°F to 200°F, the latter melting points being determined by ASTM method D 127-60; (3) atactic polypropylene having a Ring and Ball softening point of from about 120°C to 160° C;

(4) synthetic waxes made by polymerizing carbon monoxide and hydrogen such as Fischer-Tropsch wax; and

(5) polyolefm waxes. As used herein, the term "polyolefin wax" refers to those polymeric or long-chain entities comprised of olefϊnic monomer units. These materials are commercially available from Eastman Chemical Co. under the trade name "Epolene." The materials which are preferred to use in the compositions of the present invention have a Ring and Ball softening point of 200°F to 350°F. As should be understood, each of these wax diluents is solid at room temperature. Other useful substances include hydrogenated animal, fish and vegetable fats and oils such as hydrogenated tallow, lard, soya oil, cottonseed oil, castor oil, menhadin oil, cod liver oil, etc., and which are solid at ambient temperature by virtue of their being hydrogenated, have also been found to be useful with respect to functioning as a wax diluent equivalent. These hydrogenated materials are often referred to in the adhesives industry as "animal or vegetable waxes." Additionally, hydrocarbon oils, especially naphthenic or paraffinic process oils, may also be employed herein as the wax diluent.

Fillers may also be incorporated into the adhesive composition in amounts ranging from 0% to 80% by weight, preferably 0% to 10% by weight. These are inert in the formulation, and are typically added as an anti-blocking agent. Fillers may include hydrated alumina (AI2O3-3H2O), silicates such as magnesium silicates, aluminum silicate, sodium silicate, potassium silicate and the like, mica, calcium carbonate (CaCO₃) and silica. Other commonly employed fillers may also be used as long as they do not materially alter the function of the remaining ingredients in the formulation.

Optional conditioning additives may be incorporated into the adhesive composition in order to modify particular physical properties. These additives may include colorants, such as titanium dioxide, defoamers, sequestrants, deionized water, preservatives, biocides, antiblocking agents, anticling agents, pH adjusters, surfactants, thickeners and other commonly known and used additives. As noted above, such additives can be present in amounts ranging from 0% to about 38% by weight.

As previously described, pH adjusters of from 0% to 5%, preferably 0.1% to 1.5%, by weight, may be added to the adhesive composition. Typical pH adjusters include ammonia, alkanol amines, primary amines, secondary amines, tertiary amines, sodium hydroxide, potassium hydroxide, 2-amino- l-propanol, 3-amino-l-propanol, various salts such as, carbonates, phosphates, citrates, acetates, along with their corresponding acids, and other common chemicals used for adjusting pH. 0% to 5%, preferably 0.01% to 0.8%, of a biocide which functions to prevent degradation of the adhesive by microorganisms such as yeast, fungi, bacteria, molds and mildew, as packaged for shelf life preservation may also be added to the adhesive composition. Typical biocides are benzoates, phenols, aldehydes, halogen containing compounds, nitrogen compounds, and metal containing compounds, such as, mercurials, zinc compounds and tin compounds with the preferred biocide being Proxel GXL, a l,2-benzisothiazolin-3-one available from Zeneca, Inc. Defoamers in the amount of 0% to 5%, preferably 0.05% to 1.5%, may also be added to the adhesive composition. Typical defoamers include silicone-based, mineral oil-based, surfactant-based, and kerosene-based compounds with the preferred defoamer being DEEFO-97-2, a mineral oil- based defoamer available from Ultra Additives, Inc. Opacifers in amounts ranging from 0% to 5%, preferably 0% to 2.5% may also be added to the adhesive composition. Opacifers are added to the adhesive composition to insure that one substrate cannot be seen through or bleed through to the other substrate, particularly when one substrate is a paper. Typical opacifers include titanium dioxide, calcium carbonate, barium sulfate, and other light reflecting powdered minerals or metallic oxides with the preferred opacifer being Contax AQ White, a titanium dioxide dispersion, available from Sun Chemical.

From about 0% to 5%, preferably 0% to 2.5% of a thickener may also be added to the adhesive composition. Thickeners are used to increase the viscosity of the resultant adhesive without substantially affecting its adhesive characteristics. Typical thickeners include polyacrylic acid, polyvinyl alcohol, cellulosic thickeners, acrylic emulsion copolymers, polyacrylic salts, alginates, xanthan gumas, guar, starch bentonites, attapulgates, and other thickening or gelling agents. The preferred thickener is Alcogum L-15, an acrylic emulsion copolymer, available from ALCO Chemical Corp.

Melt flow modifiers in amounts ranging from 0% to 25% preferably 0% to 20%, may be added to the adhesive composition. Melt flow modifiers are added to the composition to improve the flow of the dried adhesive film under heat and pressure. Typical melt flow modifiers include: phosphate esters, benzoate esters, phthalate esters, wood rosin esters, gum rosin esters, tall oil rosin esters, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, cycloaliphatic resins, all their hydrogenated counterparts, and any combinations of the aforementioned. The preferred melt flow modifiers are phosphate esters, tall oil rosin ester, and solid benzoate esters, with the most preferred being Santicizer 141, a phosphate ester plasticizer available from Monsanto.

The adhesive composition useful in the method of the present invention may be formulated using any of the techniques known in the art.

A representative example of the procedure involves placing all the components in a mixing kettle equipped with a rotor. They are then mixed under agitation and the mixing is allowed to continue until a smooth and uniform mixture is formed.

The adhesive composition of the present invention may be used in a variety of applications. For example, the resulting pressure sensitive adhesives may be coated on paper and plastic film substrates to form food packages, peelable tape and label stocks. The nonpressure sensitive adhesives may be utilized in manufacturing corrugated boxes, in carbon sealing and bookbinding applications.

They may also be used in manufacturing of toilet tissues, paper towels, wipes and other consumer products as the laminating adhesive to bind a plurality of substrate layers.

The adhesives of the present invention, in both pressure sensitive and nonpressure sensitive forms, are especially useful in assembly or constructions of food packaging to bind a substrate composed of plastic film, paper, metal foil or the like to another substrate. This second substrate may be another plastic film, paper, or metal foil. The plastic material may be, for example, polyethylene or polypropylene film.

The adhesives of the present invention can be coated or applied with a variety of application techniques known in the art, which include, for example, slot die, spray, gravure, extrusion, application wheel, or other known application apparatus. The invention is further illustrated by way of the example which are set forth below:

EXAMPLE 1 An adhesive was prepared by charging into a mixing vessel equipped with an agitator, and then stirring at room temperature until a smooth and uniform mixture was formed, the following ingredients:

Ingredient % by Weight

Hycar 26288 - Acrylic Polymer Emulsion 16.23

Aqua Ammonia - pH adjuster and Biocide 0.626

Deefo 97-2 - Defoamer 0.2

Rovene 4020 low odor Styrene Butadiene 72.88 Elastomer - Polymer Emulsion

Lovel 29 - Filler 0.96

Michemlube 156F Carnauba Wax 0.4

Emulsion - Other Additive

Aerosol MA-80I - Stabilizer 0.192

Deionized Water 4.512

ABSCENT 2000 - Zeolite 2.0

ABSCENT 3000 - Zeolite 2.0

EXAMPLE 2

Another adhesive was prepared as described in Example 1 , except utilizing the following ingredients:

Ingredient % by Weight

Hycar 26288 - Polymer Emulsion 20.6

Aqua Ammonia-pH adjuster and Biocide 0.58

Deefo 97-2 - Defoamer 0.19

Carbotac XPD- 1814 - Polymer Emulsion 70.0 Ingredient % by Weight Lovel 29 - Filler 0.77 Colloids 999 - Defoamer 0.19 Aerosol MA-80I - Stabilizer 0.19 Deionized Water 3.48 ABSCENT 2000 - Zeolite 2.0 ABSCENT 3000 - Zeolite 2.0

EXAMPLE 3

The following adhesive was prepared as described in Example 1, but without any zeolite or other adsorbent:

Formula for 1286-192D

Ingredient % by Weight

Hycar 26288 - Acrylic Polymer Emulsion 16.88

Aqua Ammonia - pH adjuster and Biocide 0.58

Deefo 97-2 - Defoamer 0.21

Rovene 4020 low odor Styrene Butadiene 76.02 Elastomer-Polymer Emulsion

Carboset 515 - Liquid, alkali soluble 0.30 carboxylated acrylic - plasticizer

Lovel 29 - Filler 1.00

Michemlube 156F Carnauba Wax 0.42

Emulsion - Other Additive

Aerosol MA-80I - Stabilizer 0.05

Deionized Water 4.54

EXAMPLE 4 The following adhesive was prepared as described in Example 1 , but without any zeolite or other adsorbent: Formula for 1286- 192E

Ingredient % by Weight

Hycar 26288 - Acrylic Polymer Emulsion 16.91

Aqua Ammonia - pH adjuster and Biocide 0.65

Deefo 97-2 - Defoamer 0.21

Rovene 4020 low odor Styrene Butadiene 75.92 Elastomer-Polymer Emulsion

Lovel 29 - Filler 1.00

Michemlube 156F Carnauba Wax 0.42

Emulsion - Other Additive

Aerosol MA-80I - Stabilizer 0.20

Deionized Water 4.69

EXAMPLE 5 The following adhesive was prepare as described in Example 1 , but without any zeolite or other absorbent:

Formula for 1277-31

Ingredient % by Weight

Hycar 26288 - Acrylic Polymer Emulsion 21.5

Aqua Ammonia - pH adjuster and Biocide 0.6

Deefo 97-2 - Defoamer 0.2

Carbotac XPD- 1814 - Polymer Emulsion 72.9

Lovel 29 - Filler 0.8

Colloids 999 - Defoamer 0.2

Aerosol MA-80I - Stabilizer 0.2

Deionized Water 3.6

EXAMPLE 6 Test # 1 was devised to evaluate the effect of odors on the taste of foods. The food chosen was milk chocolate. The procedure used was as follows:

1. All adhesive samples were applied to the particular substrate used in the application, using a #7 wire wound rod and dried for 30 seconds at 180°F in a forced air oven.

2. 15 seconds after removal from the oven, the samples were cut to 6.25" x 10.0", rolled up as loosely as possible with the adhesive side out and placed into washed, sterilized quart sized jars. 3. Placed in the jars was a square of Hersheys Milk Chocolate cut into 15 slices parallel to the long dimension.

4. The jars containing the adhesive coated substrate and the chocolate were incubated at 72°F for 72 hours. An additional "control" jar containing the substrate with no adhesive and the chocolate was also incubated under the same conditions.

5. The samples were then taken out of the jars and evaluated one at a time using a testing scale of 0 to 4 with 4 being the most different tasting from the control and 0 being indistinguishable from the control.

6. There were 6 persons evaluating each sample. The number following each sample in Tables 1 and 2 represents the number of persons who gave the sample that rating.

Note 1 : The substrate used in these 2 tables was a laminated structure using printed polypropylene film, MF10, to polypropylene film, RLS.

Table 1

Sample Identification 0 1 2 3 4 Average Std. Dev.

1286- 192D 0 3 1 1 1 2.0 1.3

1286-192D with 0.1% 1 1 0 3 1 2.3 1.5

Schoenmann Sample Identification 0 1 2 3 4 Average Std. Dev.

91004 Odor Mask

1286- 192D with 0.1% 0 0 1.2 0.8 Schoenmann 84172 Odor Mask

1286- 192E 0 3 3 0 0 1.5 0.5

1286- 192E with 0.1% 3 2 1 0 0 0.7 0.8 Schoenmann 91004 Odor Mask

1286-192E with 0.1% 0 1 1 1 2.3 1.0 Schoenmann 84172 Odor Mask

C1380-01 1 5 0 0 0 0.8 0.4

Control 3 2 1 0 0 0.7 0.8

CX1523-01 0 1 3 2 0 2.2 0.8

Table 2

Sample Identification 0 1 2 3 4 Average Std. Dev.

1286-192D 2 1 2 1 0 1.3 1.2

1286-192D with 5000 ppm 2 2 2 0 0 1.0 0.9

Vanillin

1286- 192E 2 3 1 0 0 0.8 0.8

1286- 192E with 5000 ppm 0 2 3 1 0 1.8 0.8

Vanillin

C1380-01 5 0 1 0 0 0.3 0.8

Control 1 3 2 0 0 1.2 0.8

Conclusion:

Table 1 shows how by adding different odorants, the taste of food (milk chocolate) can be affected.

Table 2 shows how one odorant, vanillan, can have the opposite effect on two similar formulations. EXAMPLE 7 Test #2 was devised to evaluate the effect of odors on the taste of foods. The food chosen was milk chocolate. The procedure used was as follows: 1. All adhesive samples were applied to the particular substrate used in the application, using a #7 wire wound rod and dried for 30 seconds at 180°F in a forced air oven.

2. 15 seconds after removal from the oven, the samples were cut to 4" x 8", rolled up as loosely as possible with the adhesive side out and placed into washed, sterilized quart sized jars.

3. Placed in the jars was a square of Hersheys Milk Chocolate cut into 15 slices parallel to the long dimension.

4. The jars containing the adhesive coated substrate and the chocolate were incubated at 75°F for 48 hours. An additional "control" jar containing the substrate with no adhesive and the chocolate was also incubated under the same conditions.

5. The samples were then taken out of the jars and evaluated one at a time using a testing scale of 0 to 4 with 4 being the most different tasting from the control and 0 being indistinguishable from the control. 6. There were 4-6 persons evaluating each sample. The number following each sample in Tables 3 and 4 represents the number of persons who gave the sample that rating.

Note 1 : The substrate used in these tables was a polypropylene film, RLS without printing.

Table 3

Sample Identification 0 1 2 3 4 Average Std. Dev.

1277-31 0 2 3 1 0 1.8 0.8

1277-31 with 0.1% 1 2 2 1 0 1.5 1.0 Schoenmann 84172 Odor Mask Sample Identification 0 1 2 3 4 Average Std. Dev.

1222-31 with 0.1% 0 2 2 2 0 2.0 0.9 Schoenmann 91004 Odor Mask

1222-31 with 20 ppm Vanillin 2 3 1 0 0 0.8 0.8

C 1380-01 3 1 2 0 0 0.8 1.0

Control 1 4 1 0 0 1.0 0.6

Table 4

Sample Identification 0 1 2 3 4 Average Std. Dev.

1286- 192E 0 1 3 0 0 1.8 0.5

Control 3 1 0 0 0 0.3 0.5

1286- 192E with Zeolite, 0 4 0 0 0 1.0 0.0

Example 1

C1380-01 1 2 1 0 0 1.0 0.8

1277-31, Example 2 2 2 0 0 0 0.5 0.6 (w/ Zeolite)

Conclusion: The above data show that zeolites have a positive effect on reducing the off-taste impact of adhesives because for 1286- 192E the average rating was 1.8 versus 1286- 192E with zeolites being 1.0, and for 1277-31 the average rating was 1.8 versus 1277-31 with zeolites being 0.5.

EXAMPLE 8

The following peel testing was performed to determine whether the incorporation of a zeolite into the adhesive composition of Example 1 affects peel strength of the adhesive.

All samples were coated on OPP film, MF- 10, with a #7 wire wound rod.

For peel testing, all samples were sealed at 80 psi over a 4 inch length and tested in the T-Peel mode, at 12 inches per minute. Table 5

Sample Ave. Max Ave. Min. Ave. in Type of failure in grams in grams grams

Example 1 445 336 390 Adhesive - sample 1 side to side

Example 1 463 308 386 Adhesive - sample 2 side to side

Example 1 436 290 363 Adhesive - sample 3 side to side

Example 1 409 254 331 Adhesive - sample 4 side to side

Average 438 297 368

Std. Dev. 23 34 27

Conclusion: The incorporation of zeolites did not affect peel strength. The composition clearly functions as an adhesive even with the zeolites therein.

EXAMPLE 9

The following block testing was performed to determine whether the incorporation of a zeolite into the adhesive composition of Example 1 affects blocking of the adhesive.

For Block testing, all samples were blocked against OPP film, RLS at Room Temp, for 16 hours under 100 psi.

Table 6

Sample Max. Value in grams

Example 1 Sample 1 24

Example 1 Sample 2 32

Example 1 Sample 3 30

Example 1 Sample 4 24

Example 1 Sample 5 30 Sample Max. Value in grams

Example 1 Sample 6 32

Example 1 Sample 7 24

Example 1 Sample 8 28

Average 28

Std. Dev. 3.5

Conclusion: The incorporation of zeolites did not significantly affect blocking.

EXAMPLE 10

The identical peel testing according to Example 8 and block testing according to Example 9 was performed on the adhesive formulation 1286- 192E of Example 4 with 20 ppm vanillin added as an odor masking agent, rather than a zeolite adsorption agent.

All samples were coated on OPP film, MF-10, with a #7 wire wound rod.

For peel testing, all samples were sealed at 80 psi over a 4 inch length and tests in the T-Peel mode, at 12 inches per minute.

Table 7

Sample Ave. Max Ave. Min. Ave. in Type of m grams m grams grams failure

1286- 192E with 20 ppm 454 227 341 Adhesive - Vanillin sample 1 side to side

1286- 192E with 20 ppm 409 272 341 Adhesive - Vanillin sample 1 side to side

1286- 192E with 20 ppm 431 272 352 Adhesive - Vanillin sample 1 side to side

1286- 192E with 20 ppm 476 272 375 Adhesive - Vanillin sample 1 side to side

1286- 192E with 20 ppm 454 272 363 Adhesive - Vanillin sample 1 side to side Sample Ave. Max Ave. Min. Ave. in Type of in grams in grams grams failure

Average 445 263 354 Std. Dev. 26 20 15

For Block testing, all samples were blocked against OPP film, RLS at Room Temp, for 16 hours under 100 psi.

Table 8

Sample Max. Value in grams

1286-192E with 20 ppm Vanillin 58

1286-192E with 20 ppm Vanillin 80

1286- 192E with 20 ppm Vanillin 50

1286- 192E with 20 ppm Vanillin 54

1286- 192E with 20 ppm Vanillin 68

1286- 192E with 20 ppm Vanillin 60

1286- 192E with 20 ppm Vanillin 54

1286- 192E with 20 ppm Vanillin 64

1286- 192E with 20 ppm Vanillin 48

1286- 192E with 20 ppm Vanillin 64

Average 60.0

Std. Dev. 9.5

Conclusion: As compared to other agents, like vanillin, zeolites provide better blocking (Table 6 vs. Table 8) with comparable peel strength (Table 5 vs. Table 7).

Claims

CLAIMS I claim:

1. A water-based adhesive composition, comprising:

(a) about 20% to about 99.9% by weight of a polymer or copolymer, or blend of polymers or copolymers;

(b) about 0% to about 70% by weight of a tackifying resin; (c) about 0% to about 50% by weight of a plasticizer;

(d) about 0% to about 80% by weight of a filler;

(e) about 0% to about 38% by weight of a conditioning agent;

(f) about 0.1% to about 50% by weight of water; and (g) about 0. 1% to about 20% by weight of an adsorption agent having a sorption capacity for water of less than 10% by weight at 25°C; and wherein the components total 100% by weight of the composition.

2. The composition of claim 1 wherein said adsorption agent is a siliceous molecular sieve having at least 90% SiO tetrahedral oxide units.

3. The composition of claim 2 wherein said siliceous molecular sieve has a pore diameter of 4 Angstroms or greater.

4. The composition of claim 3 wherein said siliceous molecular sieve comprises a zeolite.

5. The composition of claim 1 wherein said polymer or copolymer is selected from the group consisting of styrene-isoprene-styrene, styrene- butadiene-styrene, styrene-ethylene-butylene-styrene, ethylene-vinyl- acetate, amorphous polyalpha olefin, styrene-butadiene-rubber, styrene acrylic, and acrylate or methacrylate esters.

6. The composition of claim 1 wherein the tackifying resin is selected from the group consisting of aliphatic hydrocarbon resins, hydrogenated aromatic hydrocarbon resins, hydrogenated aliphatic hydrocarbon resins or rosin esters.

7. The composition of claim 1 further including from about 0.1% to about 3% of a stabilizer.

8. The composition of claim 7 wherein said stabilizer comprises a hindered phenol.

9. The composition of claim 2 wherein the siliceous molecular sieve has a pore diameter of 6 Angstroms or greater.

10. A water-based adhesive composition, comprising:

(a) about 80% to about 99.9% by weight of a polymer or copolymer, or blend of polymers or copolymers;

(b) about 0% to about 5% by weight of a tackifying resin; (c) about 0% to about 10% by weight of a plasticizer;

(d) about 0% to about 2% by weight of a filler;

(e) about 0.4% to about 4.5% by weight of a conditioning agent;

(f) about 0.1% to about 7.5% by weight of water; and (g) about 0.1% to about 5% by weight of a siliceous molecular sieve having a sorption capacity for water of less than 10% by weight at 25°C; and wherein the components total 100% by weight of the composition.

11. The composition of claim 10 wherein said siliceous molecular sieve has at least 90% SiO tetrahedral oxide units.

12. The composition of claim 11 wherein said siliceous molecular sieve has a pore diameter of 4 Angstroms or greater.

13. The composition of claim 12 wherein said siliceous molecular sieve comprises a zeolite.