Patent ID: 6870003

Claim:
A process for producing modified thermoplastic resin by subjecting a thermoplastic resin to a modifying reaction in a molten state, said process comprising the steps of: performing the modifying reaction using carbon dioxide as the reaction medium, wherein carbon dioxide is used in a proportion of 2-200 parts by weight per 100 parts by weight of the thermoplastic resin under addition of a radical initiator in an amount of 0.01 to 3 parts by weight and an unsaturated carboxylic acid or a derivative thereof in an amount of 0.1 to 20 parts by weight; heating the thermoplastic resin in an extruding machine to melt; introducing-carbon dioxide into the molten resin under a pressure of 3-50 MPa; performing the modifying reaction of the thermoplastic resin in the presence of carbon dioxide; and removing carbon dioxide and the concomitant impurities by extraction and degasification, before the modified resin is extruded through the extrusion die.