Viscosity modifier for thermosetting resin composition

Abstract

A heat curable thermosetting epoxy resin formulation useful for making prepregs and electrical laminates containing a viscosity modifier, wherein the viscosity modifier is: (a) an optionally substituted polymer of a monovinylidene aromatic monomer, optionally having one or more further unsaturated monomers copolymerized therewith; (b) an optionally substituted polyphenylene oxide; or (c) an oxazolidone ring-containing compound.

What is claimed is:  
     
         1 . A thermosetting resin composition comprising a heat-curable thermosetting resin having a molecular weight of from about 200 to about 3000, and from about 0.5 to about 40 percent by weight, based on the resin composition, of a viscosity modifier which is a thermoplastic resin having a molecular weight of at least about 5000 and a hydroxyl content not exceeding about 0.2 hydroxyl equivalents per 100 g of the resin composition, wherein the viscosity modifier is: 
 a) an optionally substituted polymer of a monovinylidene aromatic monomer and optionally one or more further unsaturated monomers copolymerized therewith;    b) an optionally substituted polyphenylene oxide; or    c) an oxazolidone ring-containing compound.    
     
     
         2 . A method of preparing a thermosetting resin composition, which method comprises combining a heat-curable thermosetting resin having a molecular weight of from about 200 to about 3000, with from about 0.5 to about 40 percent by weight, based on the resin composition, of a viscosity modifier wherein the viscosity modifier is a thermoplastic resin having a molecular weight of at least about 5000 and a hydroxyl content not exceeding about 0.2 hydroxyl equivalents per 100 g of the resin composition, wherein the viscosity modifier is: 
 a) an optionally substituted polymer of a monovinylidene aromatic monomer and optionally one or more further unsaturated monomers copolymerized therewith;    b) an optionally substituted polyphenylene oxide; or    c) an oxazolidone ring-containing compound.    
     
     
         3 . A viscosity modifier for a heat-curable thermosetting resin composition of a thermoplastic resin wherein the thermoplastic resin has a molecular weight of at least about 5000, and a hydroxyl content not exceeding about 0.2 hydroxyl equivalents per 100 g of the resin composition, and wherein the viscosity modifier comprises: 
 a) an optionally substituted polymer of a monovinylidene aromatic monomer, optionally having one or more further unsaturated monomers copolymerized therewith;    b) an optionally substituted polyphenylene oxide; or    c) an oxazolidone ring-containing compound.    
     
     
         4 . A resin composition as claimed in  claim 1 , wherein the viscosity modifier is polystyrene, brominated polystyrene, a polyphenylene oxide, or a brominated polyphenylene oxide.  
     
     
         5 . A resin composition as claimed in  claim 1 , wherein the viscosity modifier is an oxazolidone ring-containing compound which is the reaction product of: 
 a) a polyisocyanate having an isocyanate functionality of from about 1.9 to about 2.1;    b) a polyepoxide having an epoxide functionality of from about 1.9 to about 2.1; and optionally,    c) a chain extender.    
     
     
         6 . A resin composition as claimed in  claim 5 , wherein the polyisocyanate is 2,4′-methylene-bis(phenylisocyanate)4,4′-methylene-bis(phenylisocyanate), polymeric MDI or toluene diisocyanate, or a mixture of two or more thereof.  
     
     
         7 . A resin composition as claimed in  claim 5 , wherein the polyisocyanate compound is employed in an amount of from about 15 to about 43 weight percent, based on the polyepoxide and polyisocyanate reactants.  
     
     
         8 . A resin composition as claimed in  claim 7 , wherein the polyisocyanate compound is employed in an amount of from about 20 to about 40 weight percent, based on the polyepoxide and polyisocyanate reactants.  
     
     
         9 . A resin composition as claimed in  claim 8 , wherein the polyisocyanate compound is employed in an amount of from about 25 to about 35 weight percent, based on the polyepoxide and polyisocyanate reactants.  
     
     
         10 . A resin composition as claimed in  claim 5 , wherein the polyepoxide is a diglycidyl ether of a dihydric phenol or a diglycidyl ester of a dicarboxylic acid.  
     
     
         11 . A resin composition as claimed in  claim 5 , wherein the polyepoxide is a diglycidyl ether of bisphenol-A, a diglycidyl ether of bisphenol-F, a brominated diglycidyl ether of bisphenol-A, a brominated diglycidyl ether of bisphenol-F or a mixture of two or more thereof.  
     
     
         12 . A resin composition as claimed in  claim 5 , wherein the chain extender is a dihydric phenol, a halogenated dihydric phenol, a dicarboxylicacid, a diamine, or an alkanolamine.  
     
     
         13 . A resin composition as claimed in  claim 5 , wherein the amount of the oxazolidone ring-containing compound viscosity modifier is from about 0.5 to about 20 percent in weight, based on the weight of the resin composition.  
     
     
         14 . A resin composition as claimed in  claim 5 , wherein the oxazolidone ring-containing compound viscosity modifier is an epoxy-terminated polyoxazolidone and the amount of the epoxy-terminated polyoxazolidone is from about 0.5 to about 20 percent by weight, based on the weight of the resin composition.  
     
     
         15 . A resin composition as claimed in  claim 1 , wherein the heat-curable thermosetting resin is an epoxy-terminated resin having a molecular weight of from about 200 to about 3000.  
     
     
         16 . A resin composition as claimed in  claim 15 , wherein the epoxy-terminated resin has a molecular weight of from about 200 to about 1500.  
     
     
         17 . A resin composition as claimed in  claim 1 , wherein the heat-curable thermosetting resin is a resin derived from the reaction of a polyepoxide with a polyisocyanate, and having an EEW of from about 200 to about 600.  
     
     
         18 . A resin composition, as claimed in  claim 1 , wherein the resin composition also comprises a chain extender, in an amount of from about 0.2 to about 0.5 equivalents of chain extender per epoxy equivalent in the epoxy-terminated resin.  
     
     
         19 . A resin composition as claimed in  claim 1 , wherein the heat-curable resin composition contains boric acid or a boron oxide as an inhibitor.  
     
     
         20 . A resin composition as claimed in  claim 1 , wherein the composition also comprises an accelerator.  
     
     
         21 . A resin composition as claimed in  claim 1 , wherein the composition also comprises a curing agent.  
     
     
         22 . A resin composition as claimed in  claim 21 , wherein the curing agent is a polyamine, polyamide, polyanhydride, polyphenol, or a polyacid compound.  
     
     
         23 . A thermoplastic oxazolidone ring-containing compound having a molecular weight of at least about 5000, which is the reaction product of: 
 a) from about 20 to about 43 weight percent, based on the polyepoxide and polyisocyanate reactants, of a polyisocyanate having an isocyanate functionality of from about 1.9 to about 2.1;    b) from about 80 to about 57 weight percent, based on the polyepoxide and polyisocyanate reactants, of a polyepoxide having an epoxide functionality of from about 1.9 to about 2.1; and optionally,    c) a chain extender.    
     
     
         24 . An oxazolidone ring-containing compound as claimed in  claim 23  wherein the chain extender is a dihydric phenol, a halogenated dihydric phenol, a dicarboxylicacid, a diamine, or an alkanolamine.  
     
     
         25 . An oxazolidone ring-containing compound as claimed in  claim 23 , wherein the polyepoxide is a diglycidyl ether of a dihydric phenol or a diglycidyl ester of a dicarboxylic acid.  
     
     
         26 . An oxazolidone ring-containing compound as claimed in  claim 25 , wherein the polyepoxide is a diglycidyl ether of bisphenol-A, a diglycidyl ether of bisphenol-F, a brominated diglycidyl ether of bisphenol-A, a brominated diglycidyl ether of bisphenol-F or a mixture of two or more thereof.  
     
     
         27 . A thermosetting resin composition as claimed in  claim 5 , wherein the said viscosity modifier composition comprises an oxazolidone ring-containing compound as defined in  claim 23 , in an amount such as to provide from about 0.01 to less than about 0.5 equivalents of oxazolidone, per kilogram of the thermosetting resin composition.  
     
     
         28 . A thermosetting resin composition as claimed in  claim 27 , wherein the said viscosity modifier composition comprises an oxazolidone ring-containing compound as defined in  claim 23 , in an amount such as to provide from about 0.05 to about 0.25 equivalents of oxazolidone, per kilogram of the thermosetting resin composition.  
     
     
         29 . A process for preparing a prepreg, which process comprises impregnating a reinforcing web with an epoxy resin composition, a hardener for the epoxy resin and an organic solvent, and heating the web to a temperature sufficient to partially react the epoxy resin with the hardener, characterized in that the epoxy resin composition is a resin composition as claimed in  claim 1 .  
     
     
         30 . A process for preparing an electrical laminate which process comprises laminating at least one layer of a prepreg prepared by a method as defined in  claim 29  with electrically conductive material and heating the so prepared laminate to cure the epoxy resin.  
     
     
         31 . A process for preparing a cured thermoset resin, which process comprises heating and thereby curing a thermosetting resin composition comprising a heat-curable thermosetting resin having a molecular weight of from about 200 to about 3000, and from about 0.5 to about 40 percent by weight, based on the resin composition, of a viscosity modifier which is a thermoplastic resin having a molecular weight of at least about 5000 and a hydroxyl content not exceeding about 0.2 hydroxyl equivalents per 100 g of the resin composition, wherein the viscosity modifier is: 
 a) an optionally substituted polymer of a monovinylidene aromatic monomer and optionally one or more further unsaturated monomers copolymerized therewith;    b) an optionally substituted polyphenylene oxide; or    c) an oxazolidone ring-containing compound and thermosetting resin composition.    
     
     
         32 . An article comprising a cured or B-staged resin composition as claimed in  claim 1.