Structural adhesive compositions

Abstract

Disclosed herein are compositions including (a) a first component comprising (1) an epoxy-adduct that is the reaction product of reactants comprising a first epoxy compound, a polyol, and an anhydride and/or a diacid and (2) a second epoxy compound; (b) rubber particles having a core/shell structure and/or graphenic carbon particles; and (c) a second component that chemically reacts with the first component at ambient or slightly thermal conditions. Also disclosed herein are compositions including (a) an epoxy-capped flexibilizer; (b) a heat-activated latent curing agent; and optionally (c) rubber particles having a core/shell structure and/or graphenic carbon particles; (d) an epoxy/CTBN adduct; and/or (e) an epoxy/dimer acid adduct. The heat-activated latent curing agent may include at least one reaction product of reactants including an epoxy compound and an amine and/or an alkaloid.

We claim: 
     
         1 . A composition comprising:
 (a) an epoxy-capped flexibilizer; and   (b) a heat-activated latent curing agent comprising a reaction product of reactants comprising (i) an epoxy compound, and (ii) an amine and/or an alkaloid.   
     
     
         2 . The composition of  claim 1 , wherein the epoxy-capped flexibilizer comprises a reaction product of reactants comprising:
 (i) an epoxy compound;   (iii) a polyol; and   (iv) an anhydride and/or a diacid.   
     
     
         3 . The composition of  claim 1 , wherein the epoxy-capped flexibilizer comprises a reaction product of reactants comprising:
 (i) an epoxy compound;   (iii) a polyol;   (iv) an anhydride; and   (v) a diacid.   
     
     
         4 . The composition of  claim 1 , wherein the epoxy-capped flexibilizer comprises a reaction product of reactants comprising:
 (i) an epoxy compound;   (ii) an anhydride and/or a diacid; and   (iii) a caprolactone.   
     
     
         5 . The composition of  claim 1 , wherein the epoxy-capped flexibilizer comprises a reaction product of reactants comprising:
 (i) an epoxy compound; and   (ii) a primary or secondary polyether amine.   
     
     
         6 . The composition of  claim 1 , wherein the reactants comprise an amine. 
     
     
         7 . The composition of  claim 1 , wherein the reactants comprise an alkaloid. 
     
     
         8 . The composition of  claim 1 , wherein the reactants comprise an epoxy compound, an amine, and alkaloid. 
     
     
         9 . The composition of  claim 1 , wherein the reactants comprise two epoxy compounds, an amine, and alkaloid. 
     
     
         10 . The composition of  claim 1 , wherein the epoxy compound used as a reactant comprises Bisphenol A diglycidyl ether, phenyl diglycidyl ether, glycidyl methalcrylate, or combinations thereof. 
     
     
         11 . The composition of  claim 1 , wherein the amine comprises secondary amine. 
     
     
         12 . The composition of  claim 1 , wherein the amine comprises a dimethyl amine. 
     
     
         13 . The composition of  claim 1  wherein the alkaloid comprises a diazole. 
     
     
         14 . The composition of  claim 1  wherein the alkaloid comprises an imidazole. 
     
     
         15 . The composition of  claim 1  further comprising (c) graphenic carbon particles, rubber particles having a core/shell structure, an epoxy/CTBN adduct and/or an epoxy/dimer acid adduct. 
     
     
         16 . The composition of  claim 1  further comprising (c) dicyandiamine and/or 3,4-dichlorophenyl-N,N-dimethylurea. 
     
     
         17 . The composition of  claim 1 , wherein the composition is curable at a temperature below 140° C. 
     
     
         18 . The composition of  claim 1 , wherein the composition is heat-curable within 15 minutes or less. 
     
     
         19 . A method of adhering articles comprising:
 (a) applying the composition of  claim 1  to at least one of the articles; and   (b) heating the composition at a temperature of less than 140° C. for a time of less than 15 minutes to cure the composition and thereby adhering the articles together.   
     
     
         20 . The composition of  claim 1 , which, when applied at 1 mm thick to hot dipped galvanized metal with a bond area of 20 mm×10 mm×0.25 mm, and following heating, has a measured lap shear strength of at least 15 MPa when tested at room temperature.