Process for drying thermoplastic materials

Claim 1

IN A PROCESS FOR REMOVING THE WATER FROM AND DRYING A DISPERSION OF POLYVINYL ACETATE IN WATER, THE STEPS WHICH COMPRISE REMOVING THE MAJOR PART OF THE WATER PRESENT IN THE AQUEOUS POLYVINYL ACETATE DISPERSION BY EXERTING A PRESSURE ON SAID DISPERSION TO FORCE THE WATER OUT SO THAT THE WATER CONTENT IS REDUCED TO A MAXIMUM OF ABOUT 10% BY WEIGHT, PASSING THE RESULTING MOIST POLYVINYL ACETATE UNDER SHEARING MECHANICAL FORCE THROUGH A NARROW ANNULAR WORK SPACE IN WHICH THE SURFACES FORMING THE WORK SPACE HAVE A ROTATIONAL MOVEMENT RELATIVE TO EACH OTHER AND IN WHICH THE DIAMETER OF SAID ANNULAR WORK SPACE INCREASES AND FLARES OUTWARDLY IN THE DIRECTION OF MOVEMENT OF SAID POLYVINYL ACETATE, CONVERTING THE POLYVINYL ACETATE BY THE SHEARING MECHANICAL FORCE WHILE IN SAID WORK SPACE INTO A PLURALITY OF STRANDS, IMPARTING A ROTATIONAL MOTION TO SAID STRANDS BY THE RELATIVE MOVEMENT OF THE SURFACES FORMING THE WORK SPACE WHILE SUBJECTING SAID STRANDS TO COMPRESSION SO THAT THE FRICTIONAL COMPONENT OF THE SHEARING MECHANICAL FORCE IS CONVERTED TO HEAT ENERGY THEREBY RAISING SAID POLYVINYL ACETATE STRANDS TO A TEMPERATURE ABOVE THE BOILING POINT OF WATER AND IN THE RANGE OF FROM 125*C. TO 200*C., MAINTAINING SAID POLYVINYL ACETATE STRANDS AT SAID TEMPERATURE AND SUBJECT TO SAID FORCE AND ROTATIONAL MOTION FOR A PERIOD OF FROM 0.5 TO 2 MINUTES WHILE PASSING THROUGH SAID OUTWARDLY FLARING ANNULAR WORK SPACE THEREBY TO PERMIT THE HEAT ENERGY PRODUCED TO VAPORIZE OFF SUBSTANTIALLY ALL OF THE WATER IN SAID POLYVINYL ACETATE, REMOVING SAID WATER VAPOR AND DISCHARGING THE POLYVINYL ACETATE FROM SAID NARROW ANNULAR WORK SPACE IN THE FORM OF STRANDS OF SUBSTANTIALLY DRY POLYVINYL ACETATE MATERIAL.