| 摘要 |
In a method of extruding tubular films from molten ethylene polymer or copolymer having a density of about 0.956 to about 0.960 and containing in admixture about 20% to about 40% by weight of elastomer, the extruded tube is cooled at a rate greater than 100 DEG C. per sec. at the point of crystallization by passing it over a shaped cooler. Between the extrusion die and the cooler a gaseous medium is introduced into the tube to expand it, and after leaving the cooler the gaseous medium has a pressure sufficient to maintain the diameter without expanding it. The cooler may comprise a steel or aluminium cylinder with internal water conduits. U.S.A. Specification 2,862,917 is referred to.ALSO:In a method of extruding tubing from molten ethylene polymer or copolymer having a density of about 0,956 to about 0,960 and containing in admixture about 20% to about 40% by weight of elastomer, the extruded tube is cooled at a rate greater than 100 DEG C per sec. at the point of crystallization by passing it over a shaped cooler. Between the extrusion die and the cooler a gaseous medium is introduced into the tube to expand it, and after leaving the cooler the gaseous medium has a pressure sufficient to maintain the diameter without expanding it. The cooler may comprise a steel or aluminium cylinder with internal water conduits. U.S.A. Specification 2,862,917 is referred to. |
