Reactive hot melt adhesive with improved hydrolysis resistance
View Patent ↗High green strength reactive hot melt adhesives are prepared using relatively low levels of reactive acrylic, and may be prepared with liquid crystalline or crystalline diols.
1. A moisture curable polyurethane hot melt adhesive composition having improved hydrolysis resistance including a reaction product prepared from a mixture consisting of an isocyanate, optionally a polyether polyol, an amount of one or more non-polymeric diols effective to provide improved hydrolysis resistance selected from the group consisting of aromatic diols, aliphatic diols and mixtures thereof, and a functional and/or non-functional thermoplastic polymer or mixture thereof, wherein the non-polymeric diol comprises a crystalline diol and wherein the composition has an improved hydrolysis resistance over a period of at least three days as shown by the modulus, stress and strain of the composition.
2. The adhesive of claim 1 , wherein the non-polymeric diol comprises a liquid crystalline diol.
3. The adhesive of claim 1 , wherein the crystalline diol is selected from the group consisting of 1,5-Dihydroxynaphthalene, 2′,4′-Dihydroxybenzophenone; and 4,4′-(Hexanfluroisopropylidene)diphenol, 4-hydroxyphenethyl alcohol; 2-hydroxy-4-methoxybenzyl alcohol; hydroxybenzyl alcohol, 2-(2-Hydroxyethoxy)phenol, 4-hydroxy-3-methoxybenzyl alcohol, 4-hydroxyphenethyl alcohol, hydroquinone di(beta-hydroxyethyl)ether, 2,6-Dihydroxyanthraquinone; 1,5-Dihydroxynaphthalene (DHN); Diethylstilbestrol; 9H-Fluorene-9,9-dimethanol; Eosin B, 5-tert-Butyl-4-hydroxy-2-methylphenyl sulfide; 3-(4-Carboxylphenyl)2,3-dihydro-1,1,3-trimethyl indene-5-carboxylic acid; 2′,4′-Dihydroxyacetophenone, tetramethyl benzene dimethanol, dodecane diol, cyclohexane diol, decane diol, octane diol, cyclododecane diol, hexane diol and mixtures thereof.
4. The adhesive of claim 1 , wherein the adhesive comprises from about 0.1 wt % to about 40 wt % of the non-polymeric diol.
5. The adhesive of claim 1 which comprises a non-functional acrylic polymer.
6. The adhesive of claim 1 which comprises a functional acrylic polymer.
7. The adhesive of claim 6 wherein the functional acrylic polymer is a hydroxy functional acrylic polymer.
8. The adhesive of claim 1 , wherein the one or more non-polymeric diol has a molecular weight of 2,000 or less.
9. An article of manufacture comprising the adhesive of claim 1 .
10. The adhesive of claim 1 wherein the reaction product is prepared from a mixture consisting of an isocyanate, the amount of one or more non-polymeric diols effective to provide improved hydrolysis resistance selected from the group consisting of aromatic diols, aliphatic diols and mixtures thereof, and the functional and/or non-functional thermoplastic polymer or mixture thereof.