Docket JNo.: XU3 U

TEREPHTHALATES AS PLASTICIZERS IN VINYL ACETATE POLYMER

COMPOSITIONS

FIELD OF THE INVENTION

The present invention relates to vinyl ester polymer compositions, and particularly aqueous compositions that contain vinyl acetate polymers (commonly referred to as "vinyl polymer emulsions") and one or more C ₄ to Cs alkyl terephthalates.

BACKGROUND OF THE INVENTION

Aqueous compositions containing vinyl acetate polymers have widespread applications in the area of adhesives and coatings. For example, stabilized aqueous polymer compositions containing vinyl acetate polymers have applications as adhesives for paper packaging and converting, woodwork, vinyl laminating, woven and non-woven fabrics, films, metallic foils and metallized films, and flexible cellular material such as polyurethane foams or sponge rubber. The adhesives are often prepared with polymers synthesized using emulsion polymerization and as such, are commonly referred to as "polymer emulsions." On evaporation or removal of the aqueous medium, the compositions cure or harden at room temperature to form a bond which is desirably characterized by high strength and resistance to heat, humidity and water. Some examples of vinyl acetate polymer aqueous emulsion compositions can be found in U.S. Patent Nos. 5,571,860, 6,803,403 and 6,762,239.

Additives such as plasticizers are useful with vinyl acetate polymer adhesive compositions, for example to provide lower glass transition temperatures, lower minimum film forming temperatures, and higher viscosities. However, there is a continuing need for new plasticizers for such uses.

SUMMARY OF THE INVENTION

The present invention is an aqueous composition containing at least one vinyl acetate polymer and at least one C ₄ to C ₈ alkyl terephthalate. The invention further includes articles containing the adhesives of the present invention. The invention further including methods of making and using the adhesives of the present invention.

Thus, the invention provides aqueous compositions that contain at least one vinyl acetate polymer, and at least one plasticizer comprising at least one C ₄ to C$ alkyl terephthalate, wherein the C ₄ to C ₈ alkyl terephthalate is present in an amount of at least 6% based on the total dry components of the composition. In some embodiments, the composition is an adhesive composition that includes an aqueous solution containing particles suspended in a stable emulsion in the aqueous solution. The particles contain at least one vinyl acetate polymer and at least one C4 to Cs alkyl terephthalate, and the C ₄ to Cs alkyl terephthalate is present in an amount of at least 6% based on the total dry components of the composition.

The invention further provides aqueous compositions comprising at least one vinyl acetate polymer, and di-n-butyl terephthalate. In some embodiments, the composition is an adhesive composition that includes an aqueous solution containing particles suspended in a stable emulsion in the aqueous solution. The particles contain at least one vinyl acetate polymer and di-n-butyl terephthalate.

The invention further provides methods of making one or more of the compositions of the present invention. In some embodiments, the method includes combining an aqueous solution containing at least one vinyl acetate polymer (such as a stable emulsion of particles that contain the polymer) with the C4 to Cs alkyl terephthalate.

The invention further provides articles containing any of the compositions of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are adhesive aqueous compositions that contain one or more vinyl acetate polymers and one or more C ₄ to Cs alkyl terephthalates. The composition has a wide variety of adhesive applications, including woodworking, paper packaging and converting, vinyl laminating, metal to wood adhesives, vacuum forming adhesives, and bonding various paper and nonwoven substrates. The invention further provides articles that include the compositions of the present invention. The invention further includes methods of making and using the adhesives of the present invention. The invention further includes methods of applying adhesives that are the compositions of the present invention.

Compositions of the present invention

The compositions of the present invention are aqueous compositions comprising at least one vinyl acetate polymer and at least one C ₄ to Cg alkyl terephthalate. By "aqueous composition" or "aqueous solution," it is meant that the composition contains water in an amount of at least 25% by weight. In some embodiments, the water is present in an amount of at least 40% by weight. In some embodiments, the water is present in an amount of 35 to 55% by weight. In some embodiments, the water is present in an amount of 40 to 50% by weight. In some embodiments, the aqueous composition is a stable emulsion of particles that contain the vinyl acetate polymer and the C ₄ to Cg alkyl terephthalate. By "stable emulsion," it is meant that the particles do not require agitation or heating to avoid separation at standard pressure (1 atmosphere) and room temperature (22° C), typically due to the presence of stabilizing or emulsifying compounds. Several stable emulsions of vinyl acetate polymers are known in the art. In some embodiments, the compositions are air-curable, meaning that they cure at room temperature and standard pressure by means of evaporation of the water in the compositions, without any need for heating or irradiation to cause a chemical curing process.

In some embodiments, the vinyl acetate polymer is present in the composition in the form of an aqueous dispersion at a solids level in the range of

-A-

30 to 65% by weight, or within a narrower subrange such as 35-60%, 30-40%, 50- 60%, 55-60%, 55-65%, and the like. In some embodiments the vinyl acetate polymer is present at levels of 50 to 90% parts by weight per 100 parts of the unsol vented (i.e. dry) formulation or a narrower subrange {e.g. 60 to 80%).

In some embodiments, the C ₄ to Cg alkyl terephthalate is present in amounts of 0.01 to 30 weight% of the adhesive composition. In some embodiments, the C ₄ to Cg alkyl terephthalate is present in amounts of from 3% to 30 weight %. In some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of at least 3% by weight. In some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of from 0.01 to 10 weight %. In some embodiments, the C ₄ to C ₈ alkyl terephthalate is present in amounts of from 3 to 10 weight %. In some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of from 3 to 15 weight %. In some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of from 10 to 30 weight %. In some embodiments, the C ₄ to Cg alkyl terephthalate is present in amounts of from 8% to 20 weight %. In some embodiments, the C ₄ to Cg alkyl terephthalate is present in amounts of from 6 to 30 weight %. In some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of from 8 to 30 weight %. In some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of from 5% to 8 weight %. In some embodiments, the C ₄ to Cg alkyl terephthalate is in amounts of at least 3% by weight. In some embodiments, the C4 to Cs alkyl terephthalate is in amounts of at least 4% by weight. In some embodiments, the C ₄ to Cg alkyl terephthalate is in amounts of at least 5% by weight. In some embodiments, the C ₄ to Cs alkyl terephthalate is in amounts of at least 6% by weight. In some embodiments, the C ₄ to Cg alkyl terephthalate is in amounts of at least 7% by weight. In some embodiments, the C ₄ to Cg alkyl terephthalate is in amounts of at least 8% by weight. In some embodiments, the C ₄ to Cs alkyl terephthalate is in amounts of at least 10% by weight. Any useful weight ranges of the terephthalates may be used. Thus, embodiments exist for each of the above weight percentages where such percentages are based on total weight of the compositions (i.e. weight including water or any other solvents). However, embodiments also exist in which the C ₄ to Cs alkyl terephthalate is present in each of the above weight ranges based

-S- on the total dry weight of the adhesive composition, (i.e. excluding the weight of water and any other liquid solvents). Thus, combinations of total and dry weights also exist. For example, in some embodiments, the C ₄ to Cs alkyl terephthalate is present in amounts of at least 3% by weight based on the total weight of composition, and at least 6% by weight based on the dry weight; at least 5% by weight based on the total weight of composition, and at least 6% by weight based on the dry weight; at least 5% by weight based on the total weight of composition, and at least 10% by weight based on the dry weight; at least 7% by weight based on the total weight of composition, and at least 10% by weight based on the dry weight, and so on.

CV to Cs alkyl terephthalates

As used throughout this application, "C4 to Cs alkyl terephthalate" means a compound having a structure described by Formula I:

wherein R] and R ₂ are each branched or unbranched alkyl or cycloalkyl groups of from 4 to 8 saturated and unsubstituted carbon atoms and wherein Ri and R ₂ may have identical or differing structures meeting the foregoing description. Any suitable alkyl or cycloalkyl groups can be used, but some examples include 2- ethylhexyl, n-octyl, 2 methyl pentyl, isobutyl, n-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, iso-heptyl and the like. Any such alkyl or cycloalkyl group may be used. In various embodiments, the terephthalate may be selected from a smaller group of terephthalates, such as C4 to C ₇ alkyl terephthalates, C ₄ to C ₆ alkyl terephthalates, Cg to Cs alkyl terephthalates or C ₅ to Cg alkyl terephthalates, or even smaller groups such as C ₄ to Cs alkyl terephthalates, C ₅ to Cβ alkyl terephthalates, C ₆ to C ₇ alkyl terephthalates or C ₇ to Cg alkyl terephthalates. In some embodiments, Ri and R ₂ are both n-butyl groups, making the terephthalate a di-n-butyl terephthalate. In some embodiments, Ri and R ₂ are

both isobutyl groups, making the terephthalate an isobutyl terephthalate. In some embodiments, R ₁ and R ₂ are both 2-ethylhexyl groups, making the terephthalate a bis 2-ethylhexyl terephthalate, also commonly referred to di-2-ethylhexyl terephthalate (DEHT) or dioctyl terephthalate (DOTP), which is a component of 168 Plasticizer available from Eastman Chemical Company. In some embodiments, the C ₄ to Cs alkyl terephthalate is selected from di-n-butyl terephthalate, di-2-ethylhexyl terephthalate and mixtures thereof. In some embodiments, the C ₄ to Cg alkyl terephthalate is selected from di-n-butyl terephthalate, di- isobutyl terephthalate and mixtures thereof.

Vinyl acetate polymers

As used throughout this application, "vinyl acetate polymer" means any polymer that is the reaction product of polymerization of monomers that include vinyl acetate and thus contain repeating monomers that are residues of the polymerization of vinyl acetate monomers, in which at least 80% by weight of the monomers of vinyl acetate polymers are residues of vinyl acetate monomers or are a combination of residues of vinyl acetate monomers and ethylene monomers. Vinyl acetate polymers include homopolymers formed from only vinyl acetate monomers and polymers that are the reaction product of vinyl acetate monomers along with one or more other monomers {e.g. copolymers, terpolymers, etc.). hi some embodiments the polymer has from 50 to 100 weight %, based on the total weight of the polymer, of vinyl acetate monomer residues. In some embodiments of the invention, the polymer has from 65 to 100 weight %, based on the total weight of the polymer, of vinyl acetate monomer residues. In some embodiments, the polymer has from 80 to 100 weight %, based on the total weight of the polymer, of the vinyl acetate monomer residues. In some embodiments, vinyl acetate monomer residues are present in the polymer in an amount of from 80 to 98 weight %, based on the total weight of the polymer. In some embodiments, vinyl acetate monomer residues are present in the polymer in an amount of from 80 to 93 weight %, based on the total weight of the polymer. In some embodiments, vinyl acetate monomer residues are present in the polymer in an amount of from 80 to 90 weight %, based on the total weight of the polymer.

In some embodiments, the polymer includes up to 80% by weight of residues of other ethylenically unsaturated copolymerizable monomers. For example, in some embodiments the monomers include one or more residues of alpha-olefins such as ethylene, propylene, butene, pentene, hexene, heptene, octene, or nonene. In some embodiments, the monomers include one or more residues of ethylenically unsaturated esters such as ethyl hexyl acrylate or dibutyl maleate. In some embodiments, the monomers include one or more residues of ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, or maleic acid. In some embodiments, the monomers include residues of one or more vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl 2-ethyl-hexanoate, vinyl isoctanoate, vinyl nonoate, vinyl decanoate, vinyl pivalate, or vinyl versatate, in each case referring to cis and trans isomers and combinations thereof. In some embodiments, the polymer includes residues of combinations of two or more of the foregoing monomers.

hi some embodiments, the polymer is a copolymer formed from ethylene and vinyl acetate. The exact amount of ethylene used may vary depending upon the specific end use of the composition and any amount is within the scope of the invention. In some embodiments, ethylene monomer residues are present in the copolymer in an amount from 2 to 50 weight %, based on the total weight of the copolymer. In some embodiments, ethylene monomer residues are present in the copolymer in an amount from 2 to 20 weight %, based on the total weight of the copolymer. In some embodiments, ethylene monomer residues are present in the copolymer in an amount from 7% to 20 weight %, based on the total weight of the copolymer. In some embodiments, ethylene monomer residues are present in the copolymer in an amount from 9% to 20 weight %, based on the total weight of the copolymer. In some embodiments, ethylene monomer residues are present in the copolymer in an amount from 10% to 20 weight %, based on the total weight of the copolymer. In some embodiments, ethylene monomer residues are present in the copolymer in an amount from 10% to 40 weight %, based on the total weight of the copolymer.

In some embodiments the polymer includes residues of crosslinkable monomers. Any effective type of crosslinking agents can be used, including those that crosslink during polymerization or that crosslink after polymerization. Some examples of crosslinkers that react during polymerization type include divinyl adipate, and divinyl succinate, divinyl ether, diallyl ether, triallyl cyanurate, diallyl fumarate, triallyl citrate, and diallyl maleate, and other di- or tri-allyl compounds such as diallyl melamine. Some examples of the post-reactive type crosslinking agents are glycidyl compounds such as allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, glycidyl vinyl ether, and the like; N-methylol compounds, such as N-methylol acrylamide, N-methylol methacrylamide, and their alkyl ethers, e.g., their methyl or butyl ethers.

In some embodiments of the present invention, the vinyl acetate polymer may also include residues of acrylate monomers, methacrylate monomers, monomers having a carboxylic acid group, monomers containing a sulfonic acid group, monomers containing a phosphoric acid group or nitrogen containing monoolefinically unsaturated monomer. Some examples of carboxylic acid containing monomers include C ₃ -C10 alkenoic acids, and α, β- unsaturated C ₄ -C ₁₀ alkenedioic acids. Some examples of sulfonic acid functionalized monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and sodium vinyl sulfonate. Some examples of phosphoric acid functionalized monomers include styrene phosphoric acid, sodium vinyl phosphonate, and CH ₂ =C(CH ₃ )COO(CH ₂ )NOPO ₃ H, wherein n is from 2 to 4. Some examples of nitrogen containing monoolefinically unsaturated monomer include nitriles, amides, N-methylol amides, C1-C4 alcoholic ethers of N-methylol amides, allylcarbamates, and lower alkyl ethers or lower alkanoic acid esters of N-methylol acrylamide.

The polymer may also include residues of monomers which assist in the stability of the composition. Some examples include vinyl sulfonic acid and 2- acrylamido-2-methylpropane sulfonic acid or salts thereof.

Other components in the composition

The compositions of the present invention can also contain a secondary plasticizer selected from any plasticizer conventionally used in vinyl acetate-based or ethylene vinyl acetate-based adhesives. Some examples of secondary plasticizers utilized in the adhesive compositions include, for example, acetyl tributyl citrate, butyl benzyl phthalate, butyl phthalyl butyl glycolate, dibutyl phthalate, glycerol triacetate (triacetin), dibutyl sebacate, diethyl phthalate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol dibenzoate, dipropylene glycol, an alkyl benzoate, ethyl phthalyl ethyl glycolate, ethyl-p-toluene sulfonamide, hexylene glycol, ethyl phthalyl ethyl glycolate, polyoxyethylene aryl ether, diisobutylphthalate, 2,2,4-trimethyl-l,3-pentanediol diisobutyrate, tributoxyethyl phthalate, triethylene glycol dibenzoate, phthalic acid, or combinations of any two or more of the foregoing {e.g. a combination of triacetin and 2,2,4-trimethyl-l,3-pentanediol diisobutyrate). Liquid polyesters or sulfonated types of plasticizers may also be used. In some embodiments, the secondary plasticizer is present in an amount less than 60 weight % of the total weight of plasticizers present in the adhesive composition. In some embodiments, the secondary plasticizer is less than 20 weight % of the total weight of plasticizers in the adhesive composition. In some embodiments, the secondary plasticizer is less than 10 weight % of the total weight of plasticizers in the adhesive composition.

The vinyl acetate dispersion may optionally contain polyvinyl alcohol. In some embodiments the polyvinyl alcohol is used at levels of 0.1 to 10 parts based on the total weight of the composition. In some embodiments the polyvinyl alcohol is used at levels of 0.5 to 5.0 parts based on the total weight of the composition. In some embodiments the polyvinyl alcohol is used at levels of 1 to 6 parts based on the total weight of the composition. Polyvinyl alcohols can act as stabilizers in some embodiments.

The composition of the present invention may contain any other desired or useful components such as emulsifiers, tackifiers, thickeners, defoamers,

preservatives, surfactants, fillers, humectants and the like. Some examples of suitable tackifiers include coumarone-indene, ester gum, gum rosin, hydrocarbon resins, hydrogenated rosin, phenolic modified hydrocarbon resins, rosin esters, tall oil rosins, terpene phenolic, terpene resins, toluene-sulfonamideformaldehyde resin, and wood rosin. Some examples of suitable thickeners include oliginates, bentonite, casein, fumed silica, guar gum, gum tragacanth, hydroxyethylcellulose, locust bean gum, methylcellulose, polyacrylϊc acid salts (ammonium, potassium sodium), polyvinyl alcohol, sodium carboxymethyl cellulose, and starches. Some examples of suitable fillers include bentonite, calcium carbonate, calcium silicate, clay, mica, nut shell flours, silica, talc, uncooked starches, and wood flour. Some examples of suitable humectants include calcium chloride, diethylene glycol, glycerine, hexylene glycol, propylene glycol, magnesium chloride, sodium nitrate, sorbitol, sucrose, and urea. Some examples of anionic emulsifiers include alkyl sulfonates, alkylaryl sulfonates, alkyl sulfates, sulfates of hydroxyalkanols, alkyl and alkylaryl disulfonates, sulfonated fatty acids, sulfates and phosphates of polyethoxylated alkanols and alkylphenols, as well as esters of sulfosuccinic acid. Some examples of suitable non-ionic emulsifiers include the addition products of 5 to 50 moles of ethylene oxide adducted to straight-chained and branch-chained alkanols with 6 to 22 carbon atoms, or alkylphenols, or higher fatty acids, or higher fatty amides, or primary and secondary higher alkyl amines; as well as block copolymers of propylene oxide with ethylene oxide and mixtures thereof.

Articles

The invention further includes articles comprising the composition of the present invention. The articles may include, for example, an article to which a composition of the present invention has been applied as an adhesive to two or more articles or members of an article. Some examples include paper, cardboard, and packaging materials.

Methods

The invention further includes methods of formulating the compositions of the present invention. In some embodiments, the method includes combining at

least one C ₄ to C _& alkyl terephthalate and at least one vinyl acetate polymer. In some embodiments, the method is a method to enhance the viscosity of a stable emulsion of vinyl acetate polymer particles, and comprises combining at least one C ₄ to Cg alkyl terephthalate with such emulsion.

Methods of using the compositions are also within the invention. In some embodiments, the composition is applied to an article, an opening in an article, or a juncture, joint, or connection between two or more articles or members of an article. Any effective methods can be used, and several are known in the art.

The present invention is illustrated in greater detail by the specific examples presented below. It is to be understood that these examples are illustrative embodiments and are not intended to be limiting of the invention, but rather are to be construed broadly within the scope and content of the appended claims. All patents, patent applications, publications, and literature references presented herein are incorporated by reference in their entirety for any disclosure pertinent to the practice of this invention, except that such incorporations by reference shall not change the meaning of any terms defined in this application. AU parts and percentages in the examples are on a weight basis unless otherwise stated.

EXAMPLES

Five hundred gram vinyl acetate and ethylene-vinyl acetate adhesive formulations were made using an electric DISPERMAT LC mixer. Commercially available adhesives were used (vinyl acetate compositions in Table 1; ethylene- vinyl acetate compositions in Table 2) as specified below. The "Trade name" column in Tables 1 and 2 indicates the manufacturer's product name. The "Mfg." column indicates the manufacturer name. "Forbo" indicates Forbo Adhesives LLC, 523 Davis Drive, Suite 400, Durham, NC 27713 USA; "Celanese" indicates Celanese Emulsions Gmbh, Frankfurt, Germany; "Vinavil" indicates Vinavil SpA, Villadossola Italy; "Synthomer" indicates Synthomer Ltd., Essex, UK; and "Air Products" indicates Air Products Polymers GmbH&Co KG, Johannes-Hess-Str. 24, 84489 Burghausen, Germany.

Compositions containing plasticizer compounds were prepared by adding plasticizers to each adhesive via a pipette, constantly stirring over a period of approximately 2 minutes. The following plasticizers were used:

DnBT: A composition containing at least 96% by weight of di-n-butyl terephthalate, a C4 to Cg alkyl terephthalate.

DIBP: Di-isobutyl phthalate, PALATINOL IC by BASF grade (available from Samuel Banner Ltd, Hampton Court, Tudor Road, Manor Park, Runcorn. Cheshire, WA7 ITU, UK);

2088 : BENZOFLEX 2088, a blend of diethylene glycol dibenzoate, dipropylene glycol dibenzoate and triethylene glycol dibenzoate, available from Velsicol Chemical Corp., 10400 W. Higgins Road Suite 600,Rosemont, Illinois 60018-3713, USA); and .

TXIB: EASTMAN TXIB, a plasticizer product containing 2,2,4-trimethyl- 1,3-pentanediol diisobutyrate and available from Eastman Chemical Company, Kingsport, TN USA.

Each formulation was blended at approximately 2000 rpm. Plasticizer was mixed into the compositions at 5% loading or 10% where indicated. For example, 50 grams of plasticizer would be added to 450 grams of compositions at 10% addition. In addition, 0.1% defoamer (Antifoam CF 16, available from Blackburn Chemicals) and 0.1% biocide (Acticide SPX, available from) was included in each mix. The viscosity of the plasticized composition was then determined using a Brookfϊeld viscometer at 23°C and 20 rpm. Viscosity is reported in Centipoise (cps).

Results are presented in Tables 3 and 4 below. Data points that were not measured are indicated as "nm." Brookfϊeld Viscosity was determined by ASTM Method D1084. Konig film hardness was determined by ASTM Method D4366. Minimum film-forming temperature (MFFT) was determined by ASTM Method D2354. Because the solutions were aqueous, any MTFT values recorded less than zero degrees Celsius are represented as zero degrees Celsius. In addition, values

marked as "nm*" for MFFT were not measured as during these experiments but other available data indicate that the MFFT for similar compositions would have been at or below zero degrees Celsius. Glass transition temperature (Tg) was determined by ASTM Method D3418 and determined upon second heating of the composition.

Table 1 Polyvinyl Acetate Composition used in Testing

Table 2 Ethylene- vinyl acetate Copolymer Compositions Used in Testing

Table 3

Table 4

Having described the invention in detail, those skilled in the art will appreciate that modifications may be made to the various aspects of the invention without departing from the scope and spirit of the invention disclosed and described herein. It is, therefore, not intended that the scope of the invention be limited to the specific embodiments illustrated and described but rather it is intended that the scope of the present invention be determined by the appended claims and their equivalents. Moreover, all patents, patent applications, publications, and literature references presented herein are incorporated by reference in their entirety for any disclosure pertinent to the practice of this invention except to the extent that they would alter the meaning of any terms defined herein.