Chlorination of poly(vinyl chloride) in liquid chlorine, and chlorinated

Abstract

A process is disclosed for photochlorinating poly(vinyl chloride), ('PVC'), suspended in liquid chlorine ('Cl.sub.2 ') which swells the PVC and permits chlorination to occur in a gel phase. PVC starting material is in the form of solid free-flowing macrogranules which are slurried in from about 5 to about 50 times their weight of liquid Cl.sub.2 in a reaction zone maintained at a temperature in the range from about -50.degree. C. to about 50.degree. C., and a pressure sufficient to maintain the chlorine in its liquid state. Since liquid Cl.sub.2 itself swells the PVC to provide a gel phase in which photochlorination occurs, no conventional chlorinated hydrocarbon swelling agents, catalytic materials and the like are necessary. The process may be operated as a batch process, or a continuous process. Typical chlorine content of PVC is about 56.7 percent by weight (% by wt), and the product of chlorination is chlorinated poly(vinyl chloride), ('CPVC'). When formed, this CPVC is dissolved in the liquid Cl.sub.2 to form a thick syrup-like solution. CPVC is recovered as a solid by evaporation of the liquid Cl.sub.2, or as a finely divided solid by adding a halogenated lower alkane slowly to the CPVC syrup. The solid CPVC is homogeneously chlorinated, and its morphology and spectra, especially its .sup.13 C nmr spectra, differentiate it from prior art compositions.