Amideimide sizing for carbon fiber

Abstract

Sizing for carbon fibers with uncapped or capped linear polyamideimides. The uncapped linear polyamideimides useful as carbon fiber sizings generally contain repeating units having the general formula: ##STR1## Wherein R 2 =a trivalent organic radical and generally benzenetriyl; R 3 =a divalent organic radical; and n=an integer sufficiently large to provide a strong, tough coating. Useful capped, linear polyamideimide oligomers may be formed by including end caps with an unsaturated functionality (Y) containing a residue selected from the group consisting of: ##STR2## wherein R 1 =lower alkoxy, aryl, aryloxy, substituted alkyl, substituted aryl, halogen, or mixtures thereof; j=0, 1 or 2; i=1 or 2; G=--CH 2 --, --O--, --S--, --SO 2 --, --SO--, --CO--, --CHR--, or --CR 2 --; T=methallyl or allyl; Me=methyl; and R=hydrogen, lower alkyl, or phenyl. Prepregs and composites having carbon fibers sized with such polyamideimides are also described.

What is claimed is: 
     
       1. Carbon fibers sized with a linear polyamideimide comprising repeating units having the general formula: ##STR41## wherein R 2  =a trivalent organic radical; R 3  =a divalent organic radical; and   n=a small integer.   
     
     
       2. The sized carbon fibers of claim 1 wherein R 2  is benzenetriyl. 
     
     
       3. The sized carbon fibers of claim 1 wherein R 3  is phenylene. 
     
     
       4. The sized carbon fibers of claim 1 wherein R 3  is --φ--O--φSO 2  --φ--O--φ-- wherein φ is phenylene. 
     
     
       5. Carbon fibers sized with a linear polyamideimide which is the product formed by reacting in a suitable solvent under an inert gas atmosphere a mixture comprising: (a) an acid halide anhydride of the formula: ##STR42## wherein X=halogen; and R 2  =a trivalent organic radical; and     (b) a diamine of the formula:   H.sub.2 N--R.sub.3 --NH.sub.2     wherein   R 3  =a divalent organic radical     
     
     
       6. The sized carbon fibers of claim 5 wherein R 2  is benzenetriyl. 
     
     
       7. The sized carbon fibers of claim 5 wherein R 3  is phenylene or --φ--O--φSO 2  --φ--O--φ-- wherein φ is phenylene. 
     
     
       8. The sized carbon fibers of claim 5 wherein said acid halide anhydride is trimellitic anhydride acid chloride. 
     
     
       9. The sized carbon fibers of claim 5 wherein said diamine has the general formula: ##STR43## wherein Ar=an aromatic radical; L=a sulfone linkage selected from the group consisting of --SO 2  --, --S--, --CO--, --(CH 3 ) 2  C--, and --(CF 3 ) 2  --; and   m=a small integer greater than or equal to 1.   
     
     
       10. The sized carbon fibers of claim 5 wherein said diamine is bis(4-aminophenoxyphenyl) sulfone. 
     
     
       11. Carbon fibers sized with a polyamideimide oligomer, said oligomer being selected from the group consisting of: ##STR44## wherein R 1  =lower alkyl, lower alkoxy, aryl, aryloxy, substituted alkyl, substituted aryl, halogen, or mixtures thereof; j=0, 1, or 2;   i=1 or 2;   G=--CH 2  --, --O--, --S--, --SO 2  --, --SO--, --CO--, --CHR--, or --CR 2  --;   T=methallyl or allyl;   Me=methyl;   R=hydrogen, lower alkyl, or phenyl;   R 2  =a trivalent organic radical;   R 3  =a divalent organic radical; .[.and.].   .Iadd.R 4  =a divalent organic radical; and .Iaddend.   m=a small integer.   
     
     
       12. The sized carbon fibers of claim 11 wherein R 2  is benzenetriyl. 
     
     
       13. The sized carbon fibers of claim 11 wherein R 3  is phenylene or φ--O--φ--SO 2  --φ--O--φ-- wherein φ is phenylene. 
     
     
       14. The sized carbon fibers of claim 11 wherein the oligomer is selected from the group consisting of (a) and (b). 
     
     
       15. The sized carbon fibers of claim 11 wherein said oligomer is formed by the reaction of trimellitic anhydride acid chloride, bis(4-amino-phenoxyphenyl) sulfone and p-nadimidoaniline.