Fiber-reinforced polypropylene resin composition, molding material and prepreg

A fiber-reinforced polypropylene resin composition comprising a carbodiimide-modified polyolefin (a), a polypropylene resin (b) and reinforcing fibers (c), the reinforcing fibers (c) sizing-treated with a polyfunctional aliphatic epoxy resin(s), wherein the fiber-reinforced polypropylene resin composition satisfies the requirement (I) or (II):

• (I) the content of the carbodiimide group contained in a matrix resin component in the fiber-reinforced polypropylene resin composition is 0.0005 to 140 mmol based on 100 g of the matrix resin component;
• or
• (II) the fiber-reinforced polypropylene resin composition contains 0.01 to 50 parts by mass of the component (a), 20 to 99 parts by mass of the component (b) and 1 to 80 parts by mass of the component (c) where the total of the component (b) and the component (c) is 100 parts by mass;
• and when a mold-notched Izod impact test is conducted in accordance with ASTM D256 (1983) using test pieces which are a dry sample and a water-absorbing sample prepared by immersing the dry test sample in a constant-temperature water bath at 85° for 1 week, strength retention rate (%) calculated from a ratio of the impact strength of the water-absorbing sample to the impact strength of the dry sample is 95% or more and 99% or less.