Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1993-04-30
2001-06-26
Gallagher, John J. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C524S561000, C524S564000, C524S823000, C524S833000, C525S330200, C525S369000, C428S514000
Reexamination Certificate
active
06251213
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to aqueous vinyl ester/acrylic-based laminating construction adhesive compositions with improved performance.
BACKGROUND OF THE INVENTION
Major portions of the laminating adhesives industry such as, for example, the construction adhesives industry require a laminating adhesive to permanently bond films and foils including plastic films such as, for example, plasticized polyvinyl chloride films and cellulosic foils such as, for example, decorative (printed) paper foils to construction substrates. Construction substrates include porous substrates such as, for example, particle board, plywood, hardboard, pressboard, chipboard, fiberboard, and strandboard.
Present adhesives cannot achieve a useful balance of high temperature and ambient temperature property performance in a one-part adhesive composition. In a one-part adhesive composition, a relatively hard copolymer will deliver adequate high temperature performance; however, ambient temperature performance may be inadequate. Adding a plasticizer to a relatively hard copolymer improves the ambient temperature adhesive performance but only with attrition in high temperature adhesive performance.
One solution to this problem is to employ a two-part adhesive composition in which at least one reactive copolymer is mixed with a second reactive agent, which may be low in molecular weight or polymeric. Such two-part systems are problematic in terms of handling, expense, and stability of the admixed composition.
We have now found that aqueous laminating construction adhesive compositions incorporating a one-part adhesive copolymer, the copolymer being a vinyl ester/acrylic copolymer containing from about 0.1% to about 20%, by weight based on copolymer weight, of a copolymerized polar monomer, the copolymer having a Tg from about 10 C. to about −35 C., preferably from about −5 C. to about −25 C., exhibit a good balance of high temperature and ambient temperature adhesion performance in a one-part adhesive composition.
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 4,694,056 discloses an aqueous pressure sensitive adhesive containing a copolymer of an alkyl acrylate or vinyl ester, or both, an acid functional comonomer, and a polyfunctional copolymerizable monomer.
U.S. Pat. No. 5,100,944 discloses a water-borne packaging and converting adhesive which contains 10-98 parts dispersion of a vinyl acetate homo-/co-/ter-polymer, 2-30 parts by weight of plasticizer, and 1-20 parts by weight of ethylene glycol diacetate (EGDA) as the sole organic solvent.
U.S. Pat. No. 4,540,739 discloses aqueous based pressure sensitive adhesives which incorporate a latex which contains from about 0.5 to about 40 weight percent of a C
3-9
ethylenically unsaturated carboxylic acid, the latex having been neutralized to a pH of equal to or greater than about 6 with an alkali metal hydroxide or salt.
None of the above patents disclose an aqueous laminating construction adhesive composition incorporating a one-part adhesive copolymer, the copolymer being a vinyl ester/acrylic copolymer containing from about 0.1% to about 20%, by weight based on copolymer weight, of a copolymerized polar monomer, the copolymer having a Tg from about 10 C. to about −30 C.
SUMMARY OF THE INVENTION
Aqueous vinyl ester/acrylic-based laminating construction adhesive compositions incorporating a one-part adhesive copolymer are provided. A method for laminating construction substrates is also provided.
DETAILED DESCRIPTION OF THE INVENTION
This invention is directed to aqueous laminating construction adhesive compositions incorporating a one-part adhesive copolymer, the copolymer being a vinyl ester/acrylic copolymer containing from about 0.1% to about 20%, by weight based on copolymer weight, of a copolymerized polar monomer, the copolymer having a Tg from about 10 C. to about −35 C., preferably from about −5 C. to about −25 C. which exhibit a good balance of high temperature and ambient temperature adhesion performance in a one-part adhesive composition.
Glass transition temperatures (Tgs) herein are those calculated as a weighted average of the homopolymer Tg values, that is, for calculating the Tg of a copolymer of monomers M1 and M2,
Tg
(
calc.
)=
w
(
M
1)×
Tg
(
M
1)+
w
(
M
2)×
Tg
(
M
2),
wherein
Tg(calc.) is the glass transition temperature calculated for the copolymer
w(M1) is the weight fraction of monomer M1 in the copolymer
w(M2) is the weight fraction of monomer M2 in the copolymer
Tg(M1) is the glass transition temperature of the homopolymer of M1
Tg(M2) is the glass transition temperature of the homopolymer of M2
The glass transition temperature of homopolymers may be found, for example, in “Polymer Handbook”, edited by J. Brandrup and E. H. Immergut, Interscience Publishers. By “C”, herein is meant “degrees centigrade”.
The aqueous vinyl ester/acrylic copolymers of the composition of this invention contain at least one copolymerized vinyl ester. Vinyl esters are ethylenically unsaturated ester monomers such as, for example, vinyl acetate, vinyl propionate, and vinyl versatate. Vinyl acetate is preferred.
The aqueous vinyl ester/acrylic copolymers of the composition of this invention contain at least one copolymerized acrylic monomer. Acrylic monomers are defined herein to include esters of (meth)acrylic acid, amides of (meth)acrylic acid, nitriles of (meth)acrylic acid, esters of crotonic acid, and the like.
Acrylic ester monomers such as, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and lauryl methacrylate may be used, subject to the Tg restrictions on the copolymer as stated herein. Acrylate monomers are preferred as a result of their low Tgs and the ease of polymerization with vinyl ester monomers. Butyl acrylate and 2-ethylhexyl acrylate are more preferred.
The aqueous vinyl ester/acrylic copolymers of the composition of this invention contain a copolymerized ethylenically unsaturated polar monomer such as, for example, a monomer containing a hydroxyl group such as, for example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, alkylolated amides such as, for example N-methylol (meth)acrylamide; a monomer containing an amide group such as, for example, (meth)acrylamide; a monomer containing an amino group such as, for example, dimethylaminoethyl (meth)acrylate; and a monomer containing a (carboxylic acid group,) the anhydride, or the salt thereof, such as, for example, (meth)acrylic acid, maleic acid, itaconic acid, crotonic acid, sodium vinyl sulfonate, and fumaric acid; at a level from 0.1% to about 20% by weight, based on the weight of the copolymer. Copolymerized ethylenically unsaturated carboxylic acid monomer at a level from about 0.2 to about 10% by weight, based on the weight of the copolymer is preferred. Copolymerized acrylic acid at a level from about 0.2 to about 10% by weight, based on the weight of the copolymer is more preferred.
When a carboxylic acid is incorporated into the aqueous vinyl ester/acrylic copolymer, the acid groups may be partially or wholly neutralized. Preferred is neutralization of about 5% to 200% of the equivalents of copolymerized acid. More preferred is neutralization of about 25% to 100% of the equivalents of copolymerized acid. The copolymerized carboxylic acid groups may be neutralized with a nonvolatile base such that substantially all of the nonvolatile base remains in the adhesive composition during the drying process. The copolymerized carboxylic acid groups may be neutralized with inorganic or organic bases or with salts of bases with weak acids such as, for example, sodium formate, potassium lactate, sodium citrate, potassium acetate, and sodium carbonate.
When low levels of precrosslinking or gel content are desired, low levels of multi-ethylenically unsaturated monomers such as, for example, allyl (meth)acrylate, diallyl phthalate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)
Bartman Benjamin
Eisenhart Eric Karl
Eisenhart Joann Marie
Hughes Kathleen Anne
Bakule Ronald D.
Gallagher John J.
Rohm and Haas Company
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