AQUEOUS POLYURETHANE DISPERSION DERIVED FROM TERTIARY ALKENYL GLYCIDYL ESTERS
This invention relates to a Waterborne Polyurethane Dispersions (WPU) derived from the reaction products of tertiary alkyl glycidyl esters based hydroxyl terminal polyester polyols with polyisocyanates and chain extended with poly-functional amines and dispersed in water have shown the surprising inherent ability for self-coalescence. Furthermore the cured films have shown improved hardness and abrasion resistance over these benchmarks with a significant reduction in coalescing solvent needed to accomplish film formation.
1 . A polyurethane aqueous dispersion composition comprising a hydroxyl terminal oligomer derived from an alkyl glycidyl ester and carboxylic di-acids and anhydride hemi-ester, wherein the di-acid, the anhydride or the hemi-ester are not derived from unsaturated fatty acids, and a poly-isocyanate and a water dispersing component and a chain extender component, wherein the oligomer is characterized in that the molecular weight is between 600 and 5000, and free of meth(acrylic) derivatives.
2 . The composition of claim 1 wherein the alkyl glycidyl ester is a linear or branched alkyl glycidyl ester with an alkyl group containing from 4 to 12 carbon atoms.
3 . The composition of claims 2 wherein the alkyl glycidyl ester is a branched alkyl glycidyl ester having a tertiary alkyl chain with 4 to 12 carbon atoms.
4 . The composition of claim 1 wherein the polyisocyanate may be dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexane diisocyanate, tetramethylxylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, or, combinations thereof.
5 . The composition of claim 1 wherein the polyisocyanate is present in an amount of between 25 to 50 weight % based on total polyurethane solids content.
6 . The composition of claim 1 wherein the polyisocyanate present in an amount of between 27 to 48 weight % based upon total polyurethane solids content.
7 . The composition of claim 1 wherein the water dispersing component may be anionic or cationic or nonionic or combinations thereof.
8 . The composition of claim 1 wherein a polyol component is comprised of a hydroxyl terminal oligomer derived from an alkyl glycidyl ester and carboxylic di-acids and anhydride, wherein the alkyl chain is a tertiary alkyl chain with 4 to 12 carbon atoms.
9 . The composition of claim 8 wherein the polyol may be used as a mixture with general classes of polyols and glycols such as polyesters, polycaprolactones, polycarbonates, polyethers, short chain glycols.
10 . The composition of claim 8 wherein the polyol component is between 25 to 60 weight % based upon total polyurethane solids content.
11 . The composition of claim 1 wherein the chain extender component may be selected from aliphatic polyfunctional amines, aromatic polyfunctional amines, blocked amines, amino alcohols, polyether amines, and water.
12 . The composition of claim 1 wherein a co-solvent is present in an amount lower than 25.5 weight % based on total polyurethane solids content.
13 . The composition of claim 1 wherein the composition is preferably free of n-methylpyrolidone.
14 . The composition of claim 1 wherein the molecular weight is between 800 and 3500.
15 . The composition of claim 8 comprising 25-50 weight % diisocyanate, 25-60 weight % polyol component.
16 . The composition of claim 12 wherein the weight % level of cosolvent required for film formation at 25° C. of the resulting polyurethane polymer is 35 to 60% lower than stochiometrically equivalent polyurethane systems utilizing hexane-neopentyl adipate polyester or BDO initiated polycaprolactone or CHDM initiated polycarbonate as the polyol component.
17 . The composition of claim 1 wherein a Koenig Hardness of the resulting polyurethane polymer is 83 to 124% higher than stochiometrically equivalent polyurethane systems utilizing hexane-neopentyl adipate polyester or BDO initiated polycaprolactone as the polyol component.
18 . The composition of claim 1 17 wherein a Koenig Hardness of the resulting polyurethane polymer is 2 to 3% higher, and, the weight % level of cosolvent required for film formation at 25° C. of the resulting polyurethane polymer is 55 to 60% lower than stochiometrically equivalent polyurethane systems utilizing CHDM initiated polycarbonate as the polyol component.
19 . The composition of claim 16 wherein a Taber Abrasion resistance measured as mg loss/1000 cycles yields between 49 to 84% reduction in mg loss comparative to stochiometrically equivalent polyurethane systems utilizing hexane-neopentyl adipate polyester or BDO initiated polycaprolactone as the polyol component.
20 . The composition of claim 16 wherein a Taber Abrasion resistance measured as mg loss/1000 cycles yields between 10 to 15% reduction in mg loss comparative to stochiometrically equivalent polyurethane systems utilizing CHDM initiated polycarbonate as the polyol component.