PRODUCTION METHOD FOR CHLORINATED VINYL CHLORIDE RESIN

摘要

The present invention provides a method for producing a chlorinated polyvinyl chloride which is excellent in thermal stability (initial discoloration resistance, heat-resistant stability) and is capable of providing a transparent article. The present invention relates to a method for producing a chlorinated polyvinyl chloride through thermal chlorination of a reaction solution including a vinyl chloride aqueous suspension that contains a vinyl chloride resin in a hermetically sealable reaction vessel, the method including: step 1 of initiating thermal chlorination by heating the reaction solution to 55°C to 70°C and then introducing chlorine into the reaction vessel; step 2 of raising the temperature of the reaction solution while maintaining the temperature inside the reaction vessel not higher than the glass transition temperature of a partially chlorinated polyvinyl chloride; and step 3 of carrying out the thermal chlorination at a predetermined temperature of 85°C or higher but lower than 115°C after the chlorine content of the partially chlorinated polyvinyl chloride reaches 58% by weight or more, the steps 1 to 3 being performed under stirring at a net stirring power (Pv) inside the reaction vessel of 0.2 to 2.5 kw/m 3 per 1 m 3 of the reaction solution.