Process for the purification of polyolefins

Abstract

Abstract D R A W I N G A PROCESS FOR THE PURIFICATION OF POLYOLEFINS POLYMERIZED IN THE PRESENCE OF A CATALYST SYSTEM OF SILICON COMPOUNDS WITH SILICONHYDROGEN COMPOUNDS, METAL COMPOUNDS OF SUBGROUPS IV TO VI OF THE PERIODIC TABLE AND, OPTIONALLY, OF THE MAIN GROUP III OF THE PERIODIC TABLE, AND IN THE PRESENCE OF INERT ORGANIC SOLVENTS WHICH CONSISTS IN THE STEPS OF (1) UTILIZING, AS SAID INERT ORGANIC SOLVENT AND AS THE PURIFICATION SOLVENT, A SOLUTION OF SATURATED HYDROCARBONS HAVING 6 TO 9 CARBON ATOMS AND A CONSTANT BOILING POINT, (2) DECOMPOSIING A POLYOLEFIN SUSPENSION IN SAID SOLVENT CONTAINING SAID CATALYST SYSTEM BY THE ACTION OF SAID SOLVENT CONTAINING FROM 1% TO 40% BY VOLUME OF AN ALKANOL HAVING 2 TO 3 CARBON ATOMS AND MIXTURES THEREOF, UNDER A DRY GAS ATMOSPHERE AT A TEMPERATURE OF FROM 50*C. TO 100*C., (3) SEPARATING MOIST POLYOLEFIN FROM SAID SOLVENT, (4) WASHING SAID MOIST POLYOLEFIN WITH SAID SOLVENT CONTAINING FROM 0 TO 40% BY VOLUME OF AN ALKANOL HAVING 2 TO 3 CARBON ATOMS AND MIXTURES THEREOF AT A TEMPERATURE OF FROM 50*C. TO 100*C., (5) CONTINUOUSLY DRYING SAID WASHED MOIST POLYOLEFIN, AND (6) RECOVERING PURIFIED POLYOLEFINS SUBSTANTIALLY FREE OF ASH AND LOW MOLECULAR WEIGHT POLYMERS. OPTIONALLY, (1) THE POLYOLEFIN SUSPENSION FROM THE POLYMERIZATION MAY BE SEPARATED FROM THE INERT SOLVENT AND WASHED WITH THE SOLVENT MIXTURE BEFORE THE DECOMPOSING STEP, (2) THE WASHED MOIST POLYOLEFIN MAY BE PULPED WITH THE SOLVENT ALCOHOL MIXTURE, THE SUSPENSION SEPARATED AND THE MOIST POLYOLEFIN AGAIN WASHED WITH THE SOLVENT ALCOHOL MIXTURE, (3) THE DECOMPOSING STEP MAY BE CONDUCTED IN THE PRESENCE OF SMALL AMOUNTS OF AIR OR OXYGEN AND (4) THE CONTINUOUS DRYING STEP MAY BE CONDUCTED IN THE PRESENCE OF SMALL AMOUNTS OF STEAM.

Inventors

• 👤 A Hundmeyer
• 👤 F Lochner
• 👤 G Piekarski

Bibliographic Details