Moisture-curing, hot-melt polyurethane adhesive compositions
First Claim
1. A moisture-curing, hot-melt, polyurethane adhesive composition comprising an isocyanate-terminated polyurethane prepolymer based on a polyester or a polyether and having a melting point of 40°
- -60°
C. or a phase transition point above room temperature, the polyurethane adhesive composition produced by a process comprising introducing an inert gas under pressure to the polyurethane composition in a molten state, and releasing the resulting polyurethane composition to ambient pressure to provide a foamed polyurethane composition, whereby the foamed composition has a cure rate at least about ten times the cure rate of the adhesive composition when not foamed.
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Abstract
A moisture-curing hot-melt polyurethane adhesive foam comprising isocyanate-terminated polyurethane prepolymers based on polyester or polyether and having a melting point of 40° to 60° C. or a glass transition point above room temperature, melted together, optionally with a nucleating agent and/or a surfactant, treated with an inert gas under pressure and released in ambient pressure is allowed to cure as a foam whereby a cure rate is achieved of at least ten times that of the composition when not foamed; extremely rapid cure rates are achieved and thick bond lines are readily obtained.
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Citations
23 Claims
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1. A moisture-curing, hot-melt, polyurethane adhesive composition comprising an isocyanate-terminated polyurethane prepolymer based on a polyester or a polyether and having a melting point of 40°
- -60°
C. or a phase transition point above room temperature, the polyurethane adhesive composition produced by a process comprising introducing an inert gas under pressure to the polyurethane composition in a molten state, and releasing the resulting polyurethane composition to ambient pressure to provide a foamed polyurethane composition, whereby the foamed composition has a cure rate at least about ten times the cure rate of the adhesive composition when not foamed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- -60°
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18. A method for enhancing the cure rate of a moisture-curing, hot-melt, polyurethane adhesive composition that comprises an isocyanate-terminated polyurethane prepolymer based on a polyester or a polyether and having a melting point 40°
- -60°
C. or a phase transition point above room temperature, the method comprising;(a) introducing an inert gas under pressure to the polyurethane composition in a molten state; (b) releasing the resulting polyurethane composition to ambient pressure to provide a foamed polyurethane composition; and (c) curing the foamed composition at a rate of at least about ten times the cure rate of the polyurethane composition when not foamed. - View Dependent Claims (19, 20, 21, 22, 23)
- -60°
Specification