GB569043A - Improvements in or relating to modified polymers of ethylene - Google Patents

Abstract

Modified polymers of ethylene, ranging from wax-like to grease-like and oily products, are obtained by subjecting polythene to heat treatment, in the absence of air or oxidizing agents, at a temperature above 290 DEG C., preferably 330-600 DEG C. for an appropriate time and preferably until no further pyrolysis occurs. Products of particular consistency may be obtained either by complete pyrolysis at the appropriate temperature, or by partial pyrolysis at a higher temperature; data correlating temperature, time and consistency are given. Pyrolysis may be conducted as a batch, or as a continuous operation. The treatment may be applied to a solution of polythene in a heat-stable solvent, sufficient pressure being maintained to prevent volatilization of the solvent. Examples of batch processes are: (1) heating a polythene of molecular weight 17,000 for 2 hours at 400 DEG C. to produce a hard wax; (2) heating the same polymer, in an evacuated vessel, at 600 DEG C. for 4 hours, to obtain as distillate, an oily product suitable as a transformer oil; (3) heating a polythene of molecular weight 14,000 at 450 DEG C. for 3 hours to obtain a stiff grease, and of continuous processes; (4) forcing molten polythene, of molecular weight 14,000, through a tube heated to 450 DEG C. under nitrogen pressure at a rate such that the material remains in the heated zone for 30 minutes; and (5) extruding polythene of molecular weight 12,000 through an iron tube heated to 550 DEG C. at a rate such that it remains in the heated zone for 10 minutes to yield a tough wax. Specifications 471,590 and 578,584 are referred to.