Resin compositions with high thermoplatic loading

Abstract

Uncured thermosetting resins are loaded with relatively high amounts of solid thermoplastic resin particles to form a resin precursor. The resin precursor is heat treated so as to produce an uncured resin composition wherein the thermoplastic resin particles become substantially dissolved in the thermosetting resin without causing cure of the resin mixture. Heat treatment of highly loaded thermosetting resins in accordance with the present invention provides uncured resin compositions that are well suited for use in fabricating composite structures and particularly prepreg for use in lightning protection surface coatings.

1 . An uncured resin composition comprising: 
 a thermosetting resin component comprising one or more thermosetting resins;    a curing agent for said thermosetting resin component; and    a thermoplastic resin component comprising one or more thermoplastic resins wherein said thermoplastic resin component is combined with said thermosetting resin component by adding said one or more thermoplastic resins to said one or more thermosetting resins to form a resin precursor wherein at least one of said thermoplastic resins is initially in the form of thermoplastic resin particles and wherein said resin precursor is heated to a sufficient temperature for a sufficient time to substantially dissolve said thermoplastic resin particles without curing said thermosetting resin to thereby form said uncured resin composition.    
     
     
         2 . An uncured resin composition according to  claim 1  wherein said thermosetting resin component comprises one or more resins selected from the group consisting of epoxy, bismaleimide and cyanate ester resins.  
     
     
         3 . An uncured resin composition according to  claim 1  wherein said resin particles comprise micronized or densified thermoplastic resins that have a glass transition temperature that is above 200° C.  
     
     
         4 . An uncured resin composition according to  claim 3  wherein said resin particles comprise thermoplastic resins selected from the group consisting of micronized polethersulfone, densified polyether sulfone, micorized polyetherimide and densified polyetherimide.  
     
     
         5 . An uncured resin composition according to  claim 1  wherein said thermoplastic resin component comprises one or more of said thermoplastic resins that is substantially dissolved in said thermosetting resin prior to heating of said resin precursor.  
     
     
         6 . An uncured resin composition according to  claim 5  wherein said one or more thermoplastic resins that is substantially dissolved in said thermosetting resin prior to heating of said resin precursor comprises a thermoplastic resin selected from the group consisting of polyethersulfone, polyetherimide and polyimide.  
     
     
         7 . A prepreg designed for application to a surface of a body to provide a surface finish for said body, said prepreg comprising: 
 a) an outer finish layer consisting essentially of a an uncured resin comprising a thermosetting resin component, a curing agent for said thermosetting resin component and a thermoplastic resin component comprising one or more thermoplastic resins wherein said thermoplastic resin component is combined with said thermosetting resin component by adding said one or more thermoplastic resins to said one or more thermosetting resins to form a resin precursor wherein at least one of said thermoplastic resins is initially in the form of thermoplastic resin particles and wherein said resin precursor is heated to a sufficient temperature for a sufficient time to substantially dissolve said thermoplastic resin particles without curing said thermosetting resin to thereby form said uncured resin composition; and    b) a fiber layer comprising a plurality of fibers that are impregnated with a matrix resin.    
     
     
         8 . A prepreg according to  claim 7  wherein a layer of electrically conducting material is located between said outer finish layer and said fiber layer.  
     
     
         9 . A prepreg according to  claim 8  wherein said electrically conducting material is in the form of a mesh.  
     
     
         10 . A composite material comprising a prepreg according to  claim 7  that has been heated at a sufficient temperature for a sufficient time to cure said uncured resin composition to form said composite material.  
     
     
         11 . A method for forming a surface finish on a body comprising the steps of applying an uncured resin composition to the surface of said body and curing said uncured resin composition to form a surface finish on said body, said uncured resin composition comprising: 
 a thermosetting resin component comprising one or more thermosetting resins;    a curing agent for said thermosetting resin component; and    a thermoplastic resin component that comprises one or more thermoplastic resins wherein said thermoplastic resin component is combined with said thermosetting resin component by adding said one or more thermoplastic resins to said one or more thermosetting resins to form a resin precursor wherein at least one of said thermoplastic resins is initially in the form of thermoplastic resin particles and wherein said resin precursor is heated to a sufficient temperature for a sufficient time to substantially dissolve said thermoplastic resin particles without curing said thermosetting resin to thereby form said uncured resin composition.    
     
     
         12 . A method for forming a surface finish on a body according to  claim 11  wherein said thermosetting resin component comprises one or more resins selected from the group consisting of epoxy, bismaleimide and cyanate ester resins.  
     
     
         13 . A method for forming a surface finish on a body according to  claim 11  wherein said resin particles comprise micronized or densified thermoplastic resins that have a glass transition temperature that is above 200° C.  
     
     
         14 . A method for forming a surface finish on a body according to  claim 11  wherein said thermoplastic resin component comprises one or more of said thermoplastic resins that is substantially dissolved in said thermosetting resin prior to heating of said resin precursor.  
     
     
         15 . A method for forming a surface finish on a body according to  claim 11  which includes the additional step of making said surface finish electrically conductive by combining an electrically conducting material with said uncured resin composition.  
     
     
         16 . A method for forming a surface finish on a body according to  claim 12  wherein said electrically conducting material is a metal.  
     
     
         17 . A method for forming a surface finish on a body according to  claim 12  wherein said electrically conducting material is in the form of a mesh.  
     
     
         18 . A method for forming a surface finish on a body according to  claim 11  wherein said uncured resin composition is in the form of a prepreg.  
     
     
         19 . A method for forming a surface finish on a body according to  claim 18  wherein said prepreg comprises a layer of electrically conducting mesh that is located between an outer finish layer and a fiber layer wherein said electrically conducting mesh is impregnated with said uncured resin.  
     
     
         20 . A method for forming a surface finish on a body according to  claim 11  wherein said body is located on an aircraft.