MANUFACTURE OF FIBRIDS OF POLYOLEFINS

摘要

The present invention relates to a process for the manufacture of discrete, non-agglomerated fibrids of an alefin polymer having at 25.degree.C and X-ray crystallinity of more than 5% w/w, said fibrids having a high degree of fibrillation and a high specific surface area, being not agglomerating on evaporation of solvent therefrom, having substantially no shrinkage when left in air, and capable of being freed from solvents and precipitants in the absence of surfactants and antifoaming agents and without solvent exchange. Said process comprises (a) dissolving 0.5 to 30% w/w of said olefin polymer in a solvent which is pentane or a solvent mixture containing at least sufficient pentane to cause the polyolefin to separate in the form of discrete fibrids, said mixture containing up to 98% pentane, under pressure at a temperature of 100 to 180.degree.C, (b) passing a stream of the resultant solution at a pressure thereof of 4 to 60 atmospheres gauge and at a temperature of 100 to 180.degree.C through an orifice into a chamber which is at atmospheric pressure and has a temperature of 50 to 80.degree.C, (c) passing a fluid coaxially with said stream into said chamber to produce a field of shear forces in said chamber, (d) flashing off in said chamber essentially all of said solvent from said stream and thereby solidifying said olefin polymer, and simultaneously forming in said field of shear forces discrete fibrids of said olefin polymer having lengths of 1 to 40 mm and thicknesses between 2 and 30 .mu.m, and (e) removing from said chamber a mass of said discrete, non-agglomerated fibrids. The fibrids directly obtained may be used, for exemple, for the manufacture of paper of for the manufacture of textile-like webs.