Hardener composition for epoxy resins

Abstract

A hardener composition useful for curing epoxy resins including a blend of (a) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound; (b) a copolymer of an ethylenically unsaturated anhydride and an elastomer; and optionally (c) a stabilizing agent such as a block copolymer to prevent phase separation of components (a) and (b). The hardener composition is particularly useful in electrical laminates applications.

What is claimed is:  
     
         1 . A hardener composition useful for curing a polyepoxide resin comprising a blend of 
 (a) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound; and    (b) a copolymer of an ethylenically unsaturated anhydride and an elastomer.    
     
     
         2 . The hardener composition of  claim 1  wherein the copolymer of an ethylenically unsaturated anhydride and a vinyl compound is a copolymer of styrene and maleic anhydride (SMA).  
     
     
         3 . The hardener composition of  claim 1  wherein the copolymer of an ethylenically unsaturated anhydride and an elastomer is a maleic anhydride-modified polybutadiene (PBMA).  
     
     
         4 . The hardener composition of  claim 1  including (c) a stabilizing agent to prevent phase separation of components (a) and (b).  
     
     
         5 . The hardener composition of  claim 4  wherein the stabilizing agent is a block copolymer  
     
     
         6 . The hardener composition of  claim 4  wherein the stabilizing agent is a triblock copolymer of styrene-butadiene-methyl methacrylate (SBM).  
     
     
         7 . The hardener composition of  claim 1  including (d) a solvent.  
     
     
         8 . The hardener composition of  claim 1  including (e) a cure inhibitor.  
     
     
         9 . The hardener composition of  claim 8  wherein the cure inhibitor is boric acid.  
     
     
         10 . The hardener composition of  claim 1  which further comprises (f) a bifunctional chain extender compound capable of reacting with a polyepoxide at elevated temperatures.  
     
     
         11 . The hardener composition of  claim 1  which further comprises (g) a co-crosslinking agent.  
     
     
         12 . The hardener composition of  claim 11  wherein the co-crosslinker is a hydroxy-functional co-cross-linker having a functionality of 2.2 or more.  
     
     
         13 . The hardener composition of  claim 1  wherein the amount of the carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound present in the composition is such that the epoxy to anhydride molar ratio is between about 0.8:1.0 and about 1.2:1.0.  
     
     
         14 . The hardener composition of  claim 1  wherein the amount of component (b) present in the composition is such that the component (a) to component (b) weight ratio is between about 95:5 and about 80:20.  
     
     
         15 . The hardener composition of  claim 4  wherein the amount of stabilizing agent present in the composition is such that the component (b) to component (c) weight ratio is between about 60:40 and about 95:5.  
     
     
         16 . A process for preparing a hardener composition comprising mixing 
 (a) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound; and    (b) a copolymer of an ethylenically unsaturated anhydride of an elastomer.    
     
     
         17 . A curable epoxy resin composition comprising 
 I. at least one polyepoxide, and    II. at least one crosslinker, wherein said at least one crosslinker comprises a blend of 
 (a) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound, and  
 (b) a copolymer of an ethylenically unsaturated anhydride and an elastomer.  
   
     
     
         18 . The epoxy resin composition of  claim 17  wherein the copolymer of an ethylenically unsaturated anhydride and a vinyl compound is a copolymer of styrene and maleic anhydride (SMA).  
     
     
         19 . The epoxy resin composition of  claim 17  wherein the copolymer of an ethylenically unsaturated anhydride and an elastomer is a maleic anhydride-modified polybutadiene (PBMA).  
     
     
         20 . The epoxy resin composition of  claim 17  including (c) a stabilizing agent to prevent phase separation of components (a) and (b).  
     
     
         21 . The epoxy resin composition of  claim 20  wherein the stabilizing agent is a block copolymer  
     
     
         22 . The epoxy resin composition of  claim 20  wherein the stabilizing agent is a triblock copolymer of styrene-butadiene-methyl methacrylate (SBM).  
     
     
         23 . The epoxy resin composition of  claim 17  including (d) a solvent.  
     
     
         24 . The epoxy resin composition of  claim 17  including (e) a cure inhibitor.  
     
     
         25 . The epoxy resin composition of  claim 24  wherein the cure inhibitor is boric acid.  
     
     
         26 . The epoxy resin composition of  claim 17  which further comprises (f) a bifunctional chain extender compound capable of reacting with a polyepoxide at elevated temperatures.  
     
     
         27 . The epoxy resin composition of  claim 17  which further comprises (g) a co-crosslinking agent.  
     
     
         28 . The epoxy resin composition of  claim 27  wherein the co-crosslinker is a hydroxy-functional co-crosslinker having a functionality of 2.2 or more.  
     
     
         29 . The epoxy resin composition of  claim 17  wherein the amount of the carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound present in the composition is such that the epoxy to anhydride molar ratio is between about 0.8:1.0 and about 1.2:1.0.  
     
     
         30 . The epoxy resin composition of  claim 17  wherein the amount of component (b) present in the composition is such that the component (a) to component (b) weight ratio is between about 95:5 and about 80:20.  
     
     
         31 . The epoxy resin according to  claim 26  wherein the bifunctional chain extender compound is selected from bisphenol A, or tetrabromobisphenol A.  
     
     
         32 . The epoxy resin composition of  claim 17  including a catalytic amount of a catalyst for accelerating the reaction of the polyepoxide with the cross-linker.  
     
     
         33 . The epoxy resin composition of  claim 32 , wherein the catalyst is a heterocyclic nitrogen compound, an amine, a phosphine, an ammonium compound, a phosphonium compound, an arsonium compound, or a sulfonium compound.  
     
     
         34 . The epoxy resin composition of  claim 32 , wherein the catalyst is selected from an imidazole, or a benzimidazole.  
     
     
         35 . The epoxy resin composition of  claim 17  wherein the polyepoxide is brominated.  
     
     
         36 . The epoxy resin composition of  claim 35  wherein the polyepoxide is tetrabromobisphenol A diglycidyl ether.  
     
     
         37 . A process for preparing a curable epoxy resin composition comprising mixing 
 I. at least one polyepoxide, and    II. at least one crosslinker, wherein said at least one crosslinker comprises a blend of 
 (a) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound; and  
 (b) a copolymer of an ethylenically unsaturated anhydride and an elastomer.  
   
     
     
         38 . A fiber reinforced composite article comprising a matrix including an epoxy resin composition according to  claim 17 .  
     
     
         39 . The fiber reinforced composite article of  claim 38 , which is a laminate or a prepreg for an electric circuit.  
     
     
         40 . A fiber reinforced composite article according to  claim 39  having a dielectric constant of 4.20, or less.  
     
     
         41 . A fiber reinforced composite article according to  claim 39  having a dielectric dissipation factor of less than 0.010.  
     
     
         42 . An electric circuit component having an insulating coating of the epoxy resin composition according to  claim 17 .  
     
     
         43 . A process of producing a coated article, comprising coating an article with an epoxy resin according to  claim 17 , and heating the coated article to cure the epoxy resin.  
     
     
         44 . A prepreg comprising: 
 (a) a woven fabric,    (b) an epoxy resin, and    (c) a hardener composition comprising a blend of 
 (i) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound, and  
 (ii) a copolymer of an ethylenically unsaturated anhydride and an elastomer.  
   
     
     
         45 . A laminate comprising: 
 (a) a substrate including 
 (i) a resin composition of an epoxy resin and  
 (ii) a hardener composition comprising a blend of 
 (1) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound, and  
 (2) a copolymer of an ethylenically unsaturated anhydride and an elastomer; and  
 
   (b) a layer of metal disposed on at least one surface of said substrate.    
     
     
         46 . The laminate of  claim 45  wherein the substrate further comprises a reinforcement of a woven glass fabric, wherein the epoxy resin and the hardener are impregnated on the woven glass fabric.  
     
     
         47 . A printed wiring board (PWB) made of the laminate of  claim 45.