Epoxy resin with enhanced viscosity stability and use thereof

Abstract

The present invention provides low polyphenols (such as bisphenol A) tougheners for epoxy adhesives. The tougheners, and adhesives comprising the tougheners exhibit enhanced viscosity stability, e.g., compared to tougheners prepared from higher amounts of bisphenol A (and epoxy adhesives comprising them).

1 . A toughener composition comprising a reaction product of polytetrahydrofuran, a polyphenol, trimethylolpropane, a diisocyanate, and an organometallic catalyst, wherein the amount of the polyphenol comprises less than about 20 wt % based on weight of the toughener composition. 
     
     
         2 . The toughener composition of  claim 1 , wherein the amount of polyphenol comprises less than about 18 wt % based on weight of the toughener composition. 
     
     
         3 . The toughener composition of  claim 1 , wherein the amount of polyphenol comprises less than about 15 wt % based on weight of the toughener composition. 
     
     
         4 . An epoxy adhesive comprising the toughener composition of  claim 2  in the amount of between about 10 wt % and about 50 wt % based on total weight of the epoxy adhesive. 
     
     
         5 . The epoxy adhesive of  claim 4  comprising between about 20 wt % and about 30 wt % of the toughener composition, based on total weight of the epoxy adhesive. 
     
     
         6 . An epoxy adhesive comprising the toughener composition of  claim 2 , and a dicyandiamide. 
     
     
         7 . The epoxy adhesive of  claim 6 , further comprising at least one of an accelerator, a filler, a thixotropic agent, a viscosity regulator, silica, a diluent, an adhesion promoter, a surfactant, a wetting agent, a flexibilized epoxy agent, a gelling compound, a flame retardant, a pigment, and combinations of two or more thereof. 
     
     
         8 . A toughener composition comprising a reaction product of polytetrahydrofuran, bis-phenol A, trimethylolpropane, a diisocyanate, and an organometallic catalyst, wherein the amount of the bis-phenol A comprises less than about 20 wt % based on weight of the toughener composition. 
     
     
         9 . The toughener composition of  claim 8 , wherein the amount of bis-phenol A comprises less than about 18 wt % based on weight of the toughener composition. 
     
     
         10 . An epoxy adhesive comprising the toughener composition of  claim 9 . 
     
     
         11 . The epoxy adhesive of  claim 10  comprising between about 10 wt % and about 50 wt % of the toughener composition, based on total weight of the epoxy adhesive. 
     
     
         12 . The epoxy adhesive of  claim 11  comprising between about 20 wt % and about 30 wt % of the toughener composition, based on total weight of the epoxy adhesive. 
     
     
         13 . An epoxy adhesive comprising the toughener composition of  claim 8 , and a dicyandiamide. 
     
     
         14 . The epoxy adhesive of  claim 5 , further comprising at least one of an accelerator, a filler, a thixotropic agent, a viscosity regulator, silica, a diluent, an adhesion promoter, a surfactant, a wetting agent, a flexibilized epoxy agent, a gelling compound, a flame retardant, a pigment, and combinations of two or more thereof.