High heat resistant adhesive and sealant compositions

United States Patent（美國專利號）： 8349123

Abstract：The invention provides adhesive and sealant compositions prepared from urethane prepolymers. The urethane prepolymers are obtained by reacting the novel urethane diols, polyester polyols and polyether polyols with an excess of diisocyanate. The urethane diols are prepared by reacting excess low molecular weight diols and diisocyanates. The invention is particularly useful in end use applications such as panel lamination.

Background:Urethane prepolymer is used in many industrial applications where semistructural or even structural performance is required. Traditionally, hot melt offers better processing characteristics than one-part moisture curing liquid urethane system or two-part urethane. However, at lower crosslinking density, the heat resistance of cured hot melt is generally inferior to the other two types of urethane systems. It limits the application of hot melt urethane adhesives and sealants in key areas where heat resistance is important. There has been a constant drive to improve the high temperature mechanical property of hot melt to expand its application window. 

There are several ways to improve the heat resistance of hot melt. These methods include the use of crystalline polyester polyols and thermoplastic materials, and modification of the cross-linking density of the hot melt.

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