Stampable sheet

Abstract

A stampable sheet includes discontinuous carbon fibers and a thermoplastic resin as a matrix resin, wherein viscosity η of the stampable sheet in a state where the matrix resin in the stampable sheet is molten is η0≦η<η0 exp(0.20Vf)(Pa·s), and ratio Z of refined carbon fiber bundles (A) in which Mn/(Ln×D) is less than 8.5×10−1 (mg/mm2) to the total weight of carbon fibers in the stampable sheet is 10≦Z<70 (wt %). The configuration makes it possible to provide a stampable sheet provided with a controlled range of conditions, and to achieve both high flowability during molding and high mechanical properties after molding.

1 .- 11 . (canceled) 
     
     
         12 . A stampable sheet comprising discontinuous carbon fibers and a thermoplastic resin as a matrix resin, wherein viscosity η of said stampable sheet in a state where said matrix resin in said stampable sheet is molten is η 0 ≦η<η 0  exp(0.20Vf) (Pa·s), and a proportion Z of refined carbon fiber bundles (A) in which Mn/(Ln×D) is less than 8.5×10 −1  (mg/mm 2 ) to the total weight of carbon fibers in said stampable sheet is 10≦Z<90 (wt %), where η: apparent viscosity of said stampable sheet at a time when said matrix resin is molten (a viscosity at a temperature of a solidification start temperature of said matrix resin+50° C.), Vf: carbon fiber content (%) per unit volume of said stampable sheet, η 0 : hypothetical resin viscosity of said matrix resin obtained by extending a characteristic line up to a position of Vf=0% in a characteristic chart which is obtained by changing said Vf and represents a relationship between said Vf and the viscosity of said stampable sheet, Mn: weight of carbon fiber bundles, Ln: fiber length of carbon fibers, D: fiber diameter of carbon fibers. 
     
     
         13 . The stampable sheet according to  claim 12 , wherein said proportion Z of said carbon fiber bundles (A) to the total weight of carbon fibers in said stampable sheet is 10≦Z<70 (wt %), a proportion Y of carbon fiber bundles (B) in which Mn/(Ln×D) is 8.5×10 −1  (mg/mm 2 ) or more to the total weight of carbon fibers is 30≦Y<90 (wt %), an average value X of Mn/Ln of said carbon fiber bundles (B) is 1.1×10 −2 ≦X≦8.1×10 −2  (mg/mm), and said Y satisfies Y≦100X+30. 
     
     
         14 . The stampable sheet according to  claim 12 , wherein a standard deviation σ of a number of carbon fibers Xn forming a bundle of said carbon fiber bundles (B) in said stampable sheet satisfies 50≦σ≦400. 
     
     
         15 . The stampable sheet according to  claim 12 , wherein said fiber length Ln of carbon fibers in said stampable sheet is 5-25 mm. 
     
     
         16 . The stampable sheet according to  claim 12 , wherein said matrix resin comprises any one of polyamide, polypropylene and polyphenylene sulfide. 
     
     
         17 . The stampable sheet according to  claim 12 , wherein a single fiber flexural stiffness of carbon fibers forming said carbon fiber bundles (A) is 1.0×10 −11  to 2.8×10 −11  (Pa·m 4 ). 
     
     
         18 . The stampable sheet according to  claim 12 , wherein said η 0  satisfies 2.0×10 2 ≦η 0 ≦5.0×10 4  (Pa·s). 
     
     
         19 . The stampable sheet according to  claim 12 , wherein said viscosity η of said stampable sheet is η 0  exp(0.07Vf)≦η<η 0  exp(0.20Vf)(Pa·s), and said Vf is 5≦Vf≦70(%). 
     
     
         20 . The stampable sheet according to  claim 12 , wherein a carbon fiber aggregate in said stampable sheet comprises a carbon fiber nonwoven fabric made by a carding method. 
     
     
         21 . The stampable sheet according to  claim 12 , wherein said viscosity η of said stampable sheet is η 0 ≦η<η 0  exp(0.07Vf)(Pa·s), and said Vf is 5≦Vf≦70(%). 
     
     
         22 . The stampable sheet according to  claim 12 , wherein a carbon fiber aggregate in said stampable sheet comprises a carbon fiber nonwoven fabric made by an air laid method. 
     
     
         23 . The stampable sheet according to  claim 13 , wherein a standard deviation σ of a number of carbon fibers Xn forming a bundle of said carbon fiber bundles (B) in said stampable sheet satisfies 50≦σ≦400. 
     
     
         24 . The stampable sheet according to  claim 13 , wherein said fiber length Ln of carbon fibers in said stampable sheet is 5-25 mm. 
     
     
         25 . The stampable sheet according to  claim 14 , wherein said fiber length Ln of carbon fibers in said stampable sheet is 5-25 mm. 
     
     
         26 . The stampable sheet according to  claim 13 , wherein said matrix resin comprises any one of polyamide, polypropylene and polyphenylene sulfide. 
     
     
         27 . The stampable sheet according to  claim 14 , wherein said matrix resin comprises any one of polyamide, polypropylene and polyphenylene sulfide. 
     
     
         28 . The stampable sheet according to  claim 15 , wherein said matrix resin comprises any one of polyamide, polypropylene and polyphenylene sulfide. 
     
     
         29 . The stampable sheet according to  claim 13 , wherein a single fiber flexural stiffness of carbon fibers forming said carbon fiber bundles (A) is 1.0×10 −11  to 2.8×10 −11  (Pa·m 4 ). 
     
     
         30 . The stampable sheet according to  claim 14 , wherein a single fiber flexural stiffness of carbon fibers forming said carbon fiber bundles (A) is 1.0×10 −11  to 2.8×10 −11  (Pa·m 4 ). 
     
     
         31 . The stampable sheet according to  claim 15 , wherein a single fiber flexural stiffness of carbon fibers forming said carbon fiber bundles (A) is 1.0×10 −11  to 2.8×10 −11  (Pa·m 4 ).