PURPOSE: To provide the subject modifier consisting of a specific polyimide resin, capable of improving the adherability of the modified carbon fiber to matrix resins, leading to substantially enhancing the reinforcing effect of such modified carbon fiber.
CONSTITUTION: For example, 1,3-bis(3-aminophenoxy)benzene as diamine component is made to react with a tetracarboxylic acid dianhydride (e.g. ethylenetetracarboxylic acid dianhydride) to form a polyamic acid solution. Then, carbon fiber bundles are immersed in this solution, air-dried, and heated to carry out polyimidation, thus providing the surface of the carbon fiber with the objective modifier consisting of a polyimide resin composed of recurring unit of formula I (Y is of formula II; R is tetravalent group selected from ≥2C aliphatic groups, alicyclic groups, monocyclic aromatic groups, condensed polycyclic aromatic groups, and noncondensed polycyclic aromatic groups each with aromatic groups linked mutually either directly or via crosslinking member(s)). The resulting modified carbon fiber is improved in adherability to matrix resins, and can give a composite material substantially improved in mechanical strength by kneading it with esp. a thermoplastic resin followed by molding.
Shimamura Katsusuke
Nobuhiro Takizawa
Hiroaki Tomimoto
