Thermally stable hot melt moisture-cure polyurethane adhesive composition
AssigneeH. B. Fuller Company
InventorsVirginia C. Markevka, Sandra J. Mackey, William L. Bunnelle
Life of this patent
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Abstract
A one-package thermally stable hot melt pressure-sensitive moisture-cure polyurethane composition that can be extruded at elevated temperatures to form a hot melt glue line with very high green strength that can moisture-cure to a strong urethane adhesive bond.
Claims11
A hot melt thermosetting urethane adhesive composition having thermal stability that can be extruded as a hot melt adhesive to form an initially high green strength hot melt bond and can moisture cure to a rigid moisture cure polyurethane bond, which comprises:
- (a) an effective green bonding amount of a film-forming thermoplastic ethylene-vinyl monomer copolymer wherein the vinyl monomer comprises an acrylate monomer or a vinyl ester of a carboxylic acid compound;
- (b) an effective amount of a liquid polyurethane prepolymer composition, having a viscosity of less than 25,000 cP at 25.degree. C., comprising the reaction product of a polyfunctional hydroxy compound having a number average molecular weight of at least 1,000 and a polyfunctional isocyanate compound having an isocyanate functionality of about 2 or more at a ratio of hydroxyl groups to isocyanate groups of 0.1 to 0.7:1, sufficient to form a rigid moisture-cure bond;
- (c) a phenol-free, aromatic or aliphatic-aromatic polymer tackifier comprising a monomer selected from the group consisting of a C.sub.4-6 diene, a styrenic monomer, an indene monomer, dicyclopentadiene, and mixtures thereof;
- and
- (d) about 0 to 5 wt-% of an antioxidant.
An adhesive having both hot melt and thermosetting urethane adhesive properties which comprises:
- (a) about 10 to 50 wt-% of an ethylene vinyl acetate copolymer having a melt index of 2-90 and a vinyl acetate content of greater than 50 wt-%;
- (b) about 20 to 60 wt-% of polyurethane prepolymer comprising the reaction product of a polypropylenediol and diphenyl methane diisocyanate at a ratio of hydroxyl groups to isocyanate groups of about 0.2-0.5:1, having a viscosity of less than 10,000 cP at 25.degree. C.;
- (c) about 10 to 60 wt-% of a polymeric tackifying resin comprising a styrenic polymer compound selected from the group consisting of polystyrene and poly-alpha-methylstyrene;
- and
- (d) about 10 to 60 wt-% of an antioxidant.
Dependencies are inferred from the claim text.