One-part structural epoxy resin adhesives containing elastomeric tougheners capped with phenols and hydroxy-terminated acrylates or hydroxy-terminated methacrylates

摘要

Structural adhesives are prepared from an elastomeric toughener that contains urethane and/or urea groups, and have some terminal isocyanate groups that are capped with a phenol and other terminal isocyanate groups that are capped with a hydroxy-functional acrylate or a hydroxy-functional methacrylate. In certain embodiments, the presence of both types of capping on the toughener leads to higher impact peel strengths and a greater level of cohesive failure, than when the toughener is capped with a phenol an hydroxy-functional acrylate or hydroxy-functional methacrylate alone.

主权项

1. A one-part structural adhesive, comprising:
A) at least one epoxy resin including at least one diglycidyl ether of a polyhydric phenol; B) 8 to 30 weight percent of an elastomeric toughener containing urethane and/or urea groups, and which has capped terminal isocyanate groups, wherein from 80 to 99% of the isocyanate groups are capped with a phenol and from 1 to 20% of the isocyanate groups are capped with at least one hydroxy-functional acrylate or a hydroxy-functional methacrylate compound; C) one or more epoxy curing agents; D) a liquid rubber-modified epoxy resin, a core-shell rubber or both a liquid rubber-modified epoxy resin and a core-shell rubber; E) a curing agent F) a catalyst, and G) a latent free radical initiator that is activated by radiation or by heating to a temperature of from 80 to 130° C., wherein the adhesive cures rapidly at a temperature of 140° C. or higher but slowly if at all at a temperature of 80° C. or lower.