Patent ID: 11939465
Assignee: TORAY INDUSTRIES, INC.
Field: Surface technology, coating (Chemistry)
Classification: CPC C  B | IPC C

Claim 8:
9. A prepreg production method comprising:
a step for preparing a primary prepreg by impregnating component [A] with a first epoxy resin composition comprising components [B] to [D] but substantially free of the component [E]
[A] carbon fiber,
[B] epoxy resin,
[C] curing agent,
[D] thermoplastic resin, and
[E] particles containing a thermoplastic resin as primary component and having a volume-average particle diameter of 5 to 50 μm, and
a subsequent step for impregnating each surface thereof with a second epoxy resin composition containing at least the components [B] to [E],
wherein the component [D] of the second epoxy resin composition has a weight-average molecular weight of 2,000 to 30,000 g/mol and accounts for 8 to 15 parts by mass relative to the total quantity of the components [B] to [E] of the second epoxy resin composition, which accounts for 100 parts by mass,
wherein the second epoxy resin composition has a storage elastic modulus G′ at 25° C. of 8.0×105 to 6.0×106 Pa as measured at an angular frequency of 3.14 rad/s, giving a value of 0.085 or more as calculated by the equation (1) below, and showing a glass transition temperature of −10° C. or more and less than 7° C. as measured by differential scanning calorimetry (DSC),, log
        
         1
         ⁢
         0
        
       
       (
       
        
         
          G
          ′
         
         (
         Pa
         )
        
        ⁢
           
        at
        ⁢
           
        
         25
         ∘
        
        ⁢
          
        
         C
         .
        
       
       )
      
      -
      
       
        log
        
         1
         ⁢
         0
        
       
       (
       
        
         
          G
          ′
         
         (
         Pa
         )
        
        ⁢
           
        at
        ⁢
           
        
         40
         ∘
        
        ⁢
          
        
         C
         .
        
       
       )
      
     
     
      1
      ⁢
      5
     
    
   
   
    
     equation
     ⁢
        
     
      (
      1
      ), and
wherein the component [D] of the first epoxy resin composition and the second epoxy resin composition accounts for 4 parts by mass or more and less than 8 parts by mass relative to the total quantity of the first epoxy resin composition and the second epoxy resin composition, which accounts for 100 parts by mass.