POLYMERIC FILM

摘要

A film formed from a copolymer of ethylene and at least one mono-.alpha.-olefine has a combination of impact strength and stiffness which is such that the function is at least 750. The function is preferably at least 1000 and may be several thousands. The film may also have a high tsar strength and good tensile strength. The copolymer from which the film is formed is preferably one in which the comonomer contains at least 5 carbon atoms. The comonomer content of the polymer is typically in the range from 6.5 up to 30% by weight. The film can be produced by a tubular film technique using a temperature of 170-300.degree.C. a circumferential expansion of 1.2 to 10.0 times and a draw down of 2.5 to 50 times.