Pre-mixed catalyzed vinyl acetate polymer adhesive composition

Abstract

A pre-mixed adhesive composition comprised of a vinyl acetate polymer emulsion including a cross-linking catalyst and a cross-linking inhibitor providing a good cured water resistant Type II bond and extended shelf life so that the adhesive composition will not gel over an extended period of time and will therefore be usable for direct gluing application to semi-porous and porous substrates.

What is claimed is: 
     
       1. A pre-mixed catalyzed adhesive composition comprised of (a) an aqueous cross-linkable vinyl acetate resin emulsion .[.including polymerized.]. .Iadd.of ter-polymerized .Iaddend.vinyl acetate, in which the .[.polymerized.]. .Iadd.ter-polymerized .Iaddend.vinyl acetate is made from a monomer mixture of 80-97% vinyl acetate and 3-20% of a mixture of an alkyl ester of an acid selected from the class consisting of acrylic acid and methacrylic acid and an N-alkylol derivative of an amide of an alpha, beta-unsaturated carboxylic acid in an aqueous medium containing 3-6% by weight of a hydrocolloid selected from the class consisting of polyvinyl alcohol, hydroxyethylcellulose and carboxymethylcellulose, by weight of the monomer mixture, (b) an .[.acidic.]. .Iadd.inorganic acid .Iaddend.metal salt cross-linking catalyst selected from the class consisting of aluminum chloride, aluminum nitrate, chromic chloride and chromic nitrate in an amount of about 0.0032 to 0.025 gram .[.equivalents.]. .Iadd.moles .Iaddend.per 100 grams of the resin emulsion, and (c) a cross-linking inhibitor selected from the class consisting of .[.ammonia, alkyl amines and alkylol amines.]. .Iadd.ammonia, triethylamine, triethanolamine and N-methylethanolamine .Iaddend.wherein the mole ratio of the cross-linking inhibitor to catalyst ranges from a minimum of about 0.1 to 0.2 to a maximum of about 0.7 to 1.7. .[. 
     
     
       2.  The adhesive composition of claim 1 in which the polymerized vinyl acetate is made from a monomer mixture of about 90-98% vinyl acetate and about 2-10% of an N-alkylol derivative of an amide of an alpha, beta-unsaturated carboxylic acid, by weight..]. 
     
     
       3. The adhesive composition of claim 1 wherein the N-alkylol derivative of an amide of an alpha, beta-unsaturated carboxylic acid is N-methylol acrylamide. 
     
     
       4. The adhesive composition of claim 1 wherein the mole ratio of the inhibitor to the catalyst is sufficient to at least increase the shelf life of the resin emulsion plus catalyst alone, the adhesive composition when applied to substrates providing a cured water resistant bond of at least 50 psi when subjected to a one-half hour boil test. 
     
     
       5. The adhesive composition of claim 1 wherein the alkyl ester of acrylic acid is ethyl acrylate and the N-alkylol derivative of an amide of an alpha, beta-unsaturated carboxylic acid is N-methylol acrylamide. 
     
     
       6. The adhesive composition of claim 5 wherein the catalyst is aluminum chloride in an amount of about 0.0032 to 0.025 gram .[.equivalents.]. .Iadd.moles .Iaddend.of AlCl 3  per 100 grams of resin emulsion. 
     
     
       7. The adhesive composition of claim 6 wherein the cross-linking inhibitor is triethanolamine. 
     
     
       8. The adhesive composition of claim 7 wherein the hydrocolloid is polyvinyl alcohol. 
     
     
       9. A pre-mixed catalyzed adhesive composition comprised of (a) an aqueous cross-linkable vinyl acetate emulsion of a terpolymer made by polymerizing a monomer mixture of about 90-92% vinyl acetate, about 4-6% ethyl acrylate and about 2-5% N-methylol acrylamide, in an aqueous medium containing about 3-6% of polyvinyl alcohol.Iadd., .Iaddend.by weight of the monomer mixture, (b) an .[.acidic.]. .Iadd.inorganic acid metal salt .Iaddend.catalyst of about 0.0032 to 0.025 gram .[.equivalents.]. .Iadd.moles .Iaddend.of aluminum chloride per 100 grams of the resin emulsion and (c) a cross-linking inhibitor of triethanolamine, in a mole ratio of about 0.1-0.2 to about 0.7 to 1.7 of triethanolamine to aluminum chloride. 
     
     
       10. A structure comprising two substrates bonded together by the adhesive composition of claim 1 in a cured condition. .[.11. A structure comprising two substrates bonded together by the adhesive composition of claim 2 in a 
     
     
        cured condition..]. 12. A structure comprising two substrates bonded 
     
     
        together by the adhesive composition of claim 4 in a cured condition. 13. A structure comprising two substrates bonded together by the adhesive 
     
     
        composition of claim 5 in a cured condition. 14. A structure comprising two substrates bonded together by the adhesive composition of claim 6 in a 
     
     
        cured condition. 15. A structure comprising two substrates bonded together 
     
     
        by the adhesive composition of claim 7 in a cured condition. 16. A structure comprising two substrates bonded together by the adhesive 
     
     
        composition of claim 9 in a cured condition. .[.17.  The adhesive composition of claim 1 wherein the N-alkylol derivative of an amide of an 
     
     
        alpha, beta-unsaturated carboxylic acid is N-methylol acrylamide..]. 18. The adhesive composition of claim 1 wherein the catalyst is aluminum 
     
     
        chloride and the inhibitor is triethanolamine. 19. The adhesive composition of claim 1 wherein the hydrocolloid is polyvinyl alcohol.