Process for the aftertreatment of polyolefins

Claim 1

A PROCESS FOR THE REDUCTION OF THE BULK DENSITY OF POLYOLEFIN, AFTER COMPLETED POLYMERIZATION, TO SUBSTANTIALLY 21 TO 38 GRAMS PER LITER, WHICH COMPRISES DISSOLVING SUBSTANTIALLY 0.6 TO 50 GRAMS OF SAID POLYOLEFINS IN ONE LITER ORGANIC SOLVENT AT A TEMPERATURE OF APPROXIMATELY 80 TO 200*C. WITH THE USE OF A PROTECTIVE GAS ATMOSPHERE; SEPARATING UNDISSOLVED CONSTITUENTS BY HOT FILTRATION AT SUBSTANTIALLY ATMOSPHERIC PRESSURE; COOLING THE SOLUTION, WHILE MAINTAINING THE ORIGINAL CONCENTRATION, FOR 0.5 TO 10 HOURS TO EFFECT PRECIPITATION OF THE POLYOLEFINS; FREECING SAID POLYOLEFINS FROM THE BULK OF SAID SOLVENT BY FILTRATION; REMOVING ADHERING RESIDUAL SOLVENT BY DISPLACEMENT WITH AN OXYGEN-CONTAINING LIQUID ORGANIC COMPOUND; REMOVING SAID OXYGEN-CONTAINING LIQUID ORGANIC COMPOUND BY REPEATED WASHING WITH WATER; AND DRYING THE POLYOLEFINS IN LAYERS OF 1 TO 5 CM. DEPTH IN VACUO AND UNDER A PROTECTIVE GAS ATMOSPHERE AT TEMPERATURES BETWEEN 20 AND 150*C., BUT NOT HIGHER THAN 20*C. BELOW THE SOFTENING POINT OF SAID POLYOLEFINS.