Resin compositions of improved tolerance for high temperatures and process of producing same

Claim 1

A PROCESS FOR PREPARING A CHLORINATED POLYVINYL CHLORIDE RESIN HAVING A DENSITY AT 25*C. IN THE RANGE OF 1.43 TO 1.65 AND CHARACTERIZED IN THAT THE RESIN, WITHOUT ADDED STABILIZERS, POSSESSES A HEAT STABILITY SUCH THAT A PRESSED FILM THEREOF DOES NOT TURN BLACK WHEN EXPOSED FOR 10 MINUTES TO AIR AT A TEMPERATURE OF 375*F., SAID PROCESS COMPRISING THE STEPS OF (1) PREPARING A SUSPENSION OF A MINOR PROPORTION OF A SOLID POLYVINYL CHLORIDE RESIN IN A MAJOR PROPORTION OF A LIQUID AQUEOUS MEDIUM, THE POLYVINYL CHLORIDE RESIN BEING (A) IN MACRO-GRANULAR FORM HAVING SUBSTANTIALLY ALL ITS PARTICLES ABOVE 10 MICRONS IN DIAMETER (B) POROUS TO THE EXTENT THAT ITS PARTICLES CONTAIN BETWEEN ABOUT 5 AND 50% BY VOLUME OF PORE SPACE AND (C) OF HIGH-MOLECULAR WEIGHT SUCH THAT IT POSSESSES A SPECIFIC VISCOSITY OF AT LEAST 0.4, SAID SUSPENSION CONTAINING ABOUT 5 TO 25% BY VOLUME BASED ON THE AQUEOUS MEDIUM OF CHLOROHYDROCARBON SELECTED FROM THE CLASS CONSISTING OF MONOCHLORO METHANE, DICHLOROMETHANE AND CHLOROFORM, WHICH FUNCTIONS AS A SWELLING AGENT FOR THE SUSPENDED POLYVINYL CHLORIDE RESIN, (2) PASSING CHLORINE GAS INTO SAID SUSPENSION, WHILE SAID SUSPENSION IS MAINTAINED UNDER CONDITIONS OF RAPID AGITATION, A TEMPERATURE NO GREATER THAN ABOUT 65*C. AND IN THE SUBSTANTIAL ABSENCE OF OXYGEN, SUBSTANTIALLY TO SATURATE THE AQUEOUS PHASE OF SAID SUSPENSION WITH CHLORINE (3) PHOTO-ILLUMINATING SAID SUSPENSION, WITH CHLORINE DISSOLVED IN THE AQUEOUS PHASE THEREOF, AND WHILE MAINTAINING SAID CONDITIONS, TO INDUCE CHLORINATION REACTION BETWEEN THE DISSOLVED CHLORINE AND THE SUSPENDED, SWOLLEN, POROUS, MACRO-GRANULAR POLYVINYL CHLORIDE RESIN AND PASSING MORE CHLORINE GAS INTO SAID SUSPENSION SO THAT THERE IS ALWAYS PRESENT AN EXCESS OF DISSOLVED CHLORINE OVER THAT MOMENTARILY REACTING WITH THE SUSPENDED POLYVINYL CHLORIDE RESIN (4) TERMINATING THE CHLORINATION REACTION WHEN THE DESIRED AMOUNT OF CHLORINE HAS REACTED BY EXTINGUISHING THE PHOTO-ILLUMINATION AND (5) SEPARATING FROM SAID SUSPENSION THE SOLID MACRO-GRANULAR PRODUCT OF SAID CHLORINATION REACTION AND NEUTRALIZING SAID PRODUCT, WHEREBY TO OBTAIN THE DESIRED CHLORINTED POLYVINYL CHLORIDE RESIN.