Aqueous polyurethane dispersions useful for preparing polymers with improved moisture resistance properties
The present invention is a polyurethane dispersion that can be used to prepare polyurethane polymers which have moisture resistant properties. Moisture resistant polymers of the present invention are obtained by preparing the polymers from a polyurethane dispersion using a prepolymer formulation which includes an aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent which contains from 5 to 30 carbon atoms.
1. An aqueous polyurethane dispersion comprising polyurethane polymer particles dispersed in water wherein the polyurethane polymer particles are of an isocyanate terminated prepolymer prepared from a formulation including a polyisocyanate and a polyol mixture, wherein the polyol mixture includes at least one aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent which contains from 5 to 30 carbon atoms, and the aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent is present at a concentration of from 0.5 to 10 weight percent of the polyurethane polymer particles and said polyurethane polymer particles are dispersed with a surfactant consisting essentially of an external surfactant.
2. The aqueous polyurethane dispersion of claim 1 wherein the polyisocyanate is MDI.
3. The aqueous polyurethane dispersion of claim 1 wherein the aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent which contains from 5 to 30 carbon atoms is a glycol of a glycerin, trimethylolpropane, or trimethylolethane that has been partially esterified with a 5 to 22 carbon carboxylic acid.
4. The aqueous polyurethane dispersion of claim 3 wherein the glycol of a glycerin, trimethylolpropane, or trimethylolethane is selected from the group consisting of glycerol monooleate, glycerol monobebenate, glycerol monotallate, glycerol monostearate, glycerol monopalmitate, trimethylolpropane monostearate, and mixtures thereof.
5. The aqueous polyurethane dispersion of claim 1 wherein the aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent which contains from 5 to 30 carbon atoms is present at a concentration of from 1.0 to 4.5 weight percent of the polymer.
6. The aqueous polyurethane dispersion of claim 5 wherein the aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent which contains from 5 to 30 carbon atoms is present at a concentration of from 1.5 to 2.5 weight percent of the polymer.
7. The aqueous polyurethane dispersion of claim 1 wherein the aliphatic mono, di or polyhydroxy compound which has an aliphatic side chain substituent which contains from 5 to 30 carbon atoms is a glycerol monoester.
8. The aqueous polyurethane dispersion of claim 1 wherein the external surfactant is a triethanolamine salt of dodecyl benzene sulfonic acid.
9. The aqueous polyurethane dispersion of claim 1 wherein the polyol mixture includes a polyether polyol.
10. The aqueous polyurethane dispersion of claim 1 wherein the dispersion is prepared in the substantial absence of an organic solvent.
11. The aqueous polyurethane dispersion of claim 1 wherein the dispersion is compounded with a filler.
12. The aqueous polyurethane dispersion of claim 11 wherein the filler is selected from the group consisting of milled glass, calcium carbonate, aluminum trihydrate, talc, bentonite, antimony trioxide, kaolin, fly ash, and mixtures thereof.
13. The aqueous polyurethane dispersion of claim 11 wherein the filler is calcium carbonate.
14. The aqueous polyurethane dispersion of claim 12 , wherein the filler is milled glass.