Thermoplastic resin prepreg and method for manufacturing same

A method for manufacturing a thermoplastic resin prepreg, which includes a fiber-reinforced substrate and a thermoplastic resin composition containing a crystalline thermoplastic resin, and in which the thermoplastic resin composition is partially or completely impregnated into the fiber-reinforced substrate, wherein

• the content of the fiber-reinforced substrate in the entire thermoplastic resin prepreg is 40 to 85 [mass %],
• the method comprising a step of heating at a heat treatment temperature equal to or higher than a glass transition temperature of the thermoplastic resin composition and then cooling to the glass transition temperature or lower in a state in which the thermoplastic resin composition is impregnated into the fiber-reinforced substrate or when the thermoplastic resin composition is impregnated into the fiber-reinforced substrate, wherein an average cooling rate during the cooling satisfies Condition (A) or (B) below:
• Condition (A):
• in a case of (the heat treatment temperature)<(the glass transition temperature+150 [° C.]), the average cooling rate from the heat treatment temperature to the glass transition temperature is 80 [° C./sec] or less;
• or
• Condition (B):
• in a case of (the heat treatment temperature)>(the glass transition temperature+150 [° C.]), the average cooling rate from (the glass transition temperature+150 [° C.]) to the glass transition temperature is 80 [° C./sec] or less.