Polyphenylene sulfide block copolymer and a production method thereof

A block copolymer composed of polyphenylene sulfide units and polyorganosiloxane units, ranges glass transition temperature of 80 ° C. or less, and polyphenylene sulfide having a weight average molecular weight in the range of 35,000 or more and 100,000 or less block copolymer. Heat resistance, is excellent in heat aging resistance, provides a novel polyphenylene sulfide block copolymer having a high flexibility.