Injection molded body and method for producing same, method for producing composite fiber, cnt-attached carbon fiber and method for producing same, and method for producing carbon fiber composite

A method for manufacturing an injection molded article, comprising:

• kneading a composite fiber and a thermoplastic resin;
• and
• injection-molding the thermoplastic resin containing the composite fiber to obtain an injection molded article in which the composite fiber is embedded in a matrix resin formed of the thermoplastic resin, wherein
• the composite fiber includes
• a carbon fiber,
• a structure that includes a plurality of carbon nanotubes having a bent shape with a bent portion, that forms a network structure including a contact portion where the carbon nanotubes are in direct contact with each other, and that is provided on a surface of the carbon fiber, and
• a sizing agent that is provided around at least the contact portion to cross-link the carbon nanotubes in direct contact with each other via a structure formed by a reaction with a functional group of the carbon nanotubes.

A method for manufacturing a composite fiber, comprising:

• forming, on a surface of a carbon fiber, a structure that includes a plurality of carbon nanotubes having a bent shape with a bent portion, and that forms a network structure including a contact portion where the carbon nanotubes are in direct contact with each other;
• bringing the carbon fiber on which the structure is formed into contact with a sizing treatment solution in which a raw material of a sizing agent that cross-links the carbon nanotubes in direct contact with each other is dissolved, and applying the sizing agent to obtain a composite fiber;
• and
• post-curing the sizing agent of the composite fiber.

A method for manufacturing a carbon fiber composite material, comprising:

• preparing a composite in which a resin and a carbon fiber are integrated, the carbon fiber being provided with, on a surface thereof, a structure that includes a plurality of carbon nanotubes having a bent shape with a bent portion and that forms a network structure including a contact portion where the carbon nanotubes are in direct contact with each other;
• removing the resin from the composite to obtain a CNT-adhered carbon fiber;
• and
• obtaining a carbon fiber composite material in which the CNT-adhered carbon fiber is embedded in a matrix resin.