Abstract: The present invention produces chlorinated vinyl chloride resin from which hydrogen chloride can easily be removed and having little coloring as a molded article. Also, chlorinated vinyl chloride resin from which hydrogen chloride can easily be removed and excellent in heat resistance and thermal stability can be produced using a process for preparing chlorinated vinyl chloride resin by gas-solid contact chlorination which is excellent in simplicity of after treatment and facility costs. Chlorination is conducted rapidly and evenly by exposing vinyl chloride resin powder in a fluidized state with light from a light source located outside the powder layer, while supplying chlorine to the powder layer, by using devices such as a rotary reactor or stirring type reactor.

Abstract: A chlorinated vinyl chloride resin composition comprising 100 parts by weight of chlorinated vinyl chloride resin and a hydroxypolycarboxylic acid salt, e.g., sodium tartrate, and/or 0.2 to 1.5 parts by weight of zeolite. The composition exhibits improved thermal stability and is particularly suited to pipe extrusion.

Abstract: A chlorinated vinyl chloride resin composition comprising 100 parts by weight of chlorinated vinyl chloride resin and a hydroxypolycarboxylic acid salt, e.g., sodium tartrate, and/or 0.2 to 1.5 parts by weight of zeolite. The composition exhibits improved thermal stability and is particularly suited to pipe extrusion.

Abstract: In producing chlorinated polyvinyl chloride resin having chlorination degree of 60-73% by weight, wherein polyvinyl chloride resin is suspended in an aqueous medium and chlorine gas is blown into said suspension under beam of a mercury lamp in the temperature range of 40-90° C., an organic peroxide compound having a 10 hour half-life in the range of 40-90° C. is added into the reaction vessel in the ratio of 0.01-1 parts to 100 parts of the polyvinyl chloride resin by weight before the chlorination reaction is started. By this method, the time for chlorination reaction can be shortened without sacrificing the initial coloring and the heat stability, whereby chlorinated polyvinyl chloride can be produced with significantly improved productivity.