PROCEDE DE PREPARATION DE FIBRES DE POLYOLEFINES

摘要

1350487 Fibrous polyolefins CROWN ZELLERBACH CORP 19 April 1971 [9 April 1970 3 Sept 1970] 26826/71 Heading C3P [Also in Division D2] Polyolefin fibres are prepared by a process which comprises firstly forming a gel of high molecular weight linear polyolefin, said gel comprising a fibrillar structure of fibrous polyolefin defining a network of interconnecting capillary spaces filled with organic solvent, any shear stress applied in the formation of the gel being insufficient to form discrete polyolefin fibres, and secondly subjecting the gel to shear stress sufficient to form discrete polyolefin fibres. The gel may be prepared by polymerizing an olefin in the presence of a co-ordination catalyst in a solvent for the polymer, at a temperature below the melt dissolution temperature of the resulting polymer and at a sufficiently rapid reaction rate to effect formation of the gel. Alternatively the polymerization may be effected above the melt dissolution temperature and the resulting solution cooled, or a preformed olefin polymer may be dissolved in a solvent and the solution cooled while subjecting to shearing stress sufficient to ensure the presence of macrofibrils of diameter 1 to 20 microns in the gel but insufficient to cause the presence of discrete fibres. The gel may be subjected to shear in a conventional disc refiner to give fibres of similar size to cellulosic paper-making fibres, which fibres may be formed into non-woven webs by conventional paper-making processes. Specified monomers are ethylene, propylene, butadiene, isoprene, butene-1, pentene-1, dodecene-1 and 4-methylpentene-1; and specified solvents are oyclohexane, decalin, heptane, tetralin, xylenes, toluene, hexane, isooctane, mineral oil, noctane, p-cymene and chlorinated hydrocarbons. Many examples are given describing the preparation of polyethylene and polypropylene fibres.