| 摘要 |
A two component primerless modified urethane adhesive having good high temperature stability can be utilized to bond substrates such as sheet molded composites together which can be subsequently powder coated. The utilization of the modified adhesive generally results in the formation of channels between the cured adhesive and the sheet molded composite surface so that upon cure of the applied powder coating, volatiles can escape from the sheet molded composite thus preventing blistering of the powder paint coating. The prepolymer component of the modified urethane contains a reacted hydroxyl intermediate and has a significant excess of free isocyanate. The curative component contains a polyol curing agent, an amine sag resistant agent, a trimerization catalyst, a low amount of urethane catalyst, and optionally a phosphorus-type adhesion promoter and/or molecular sieves. The equivalent ratio of free NCO groups in the prepolymer component to OH groups plus any amine groups in the curative component is generally from about 1.2 to about 2.0.
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