US T961009 I4
antistatic polyolefin films, particularly oriented polyolefin, are produced by extruding a polyolefin to form a cast extrudate, and applying to at least one surface of the cast extrudate a solution or dispersion in a volatile vehicle an amine sulfate or mixture of amine sulfates having the general formula ##STR1## where x is a positive integer, y is zero or a positive integer, the sum of x and y is from 2 to 5, A is a hydrogen atom and when y is zero A may also be a lower alkyl group, and R is a univalent aliphatic radical containing from 8 to 22 carbon atoms, and afterwards heating and stretching the extrudate to orient it. Preferred materials include amine sulphates in which the sum of x+ y is 2, A is hydrogen and R is a mixture of aliphatic hydrocarbon radicals having 8 to 18, preferably 12 to 18, carbon atoms particularly those derived from tallow or soya oil or derived from coconut oil. Examples of suitable amines from which amine sulfates may be prepared are the Endomeen's T/12, S/12 and C/12. It has been found that the corresponding hydrochloride does not provide the oriented film with satisfactory properties. The amine sulfate is conveniently employed at a concentration of up to about 60% by weight of the solution or dispersion and preferably from 10 to 50%.
Preferably the solution or dispersion also contains as a supplementary additive a quaternary ammonium compound of the general formula: ##STR2## where each of R1, R2, and R3, which may be the same or different, is a hydrogen atom or a lower alkyl radical, or R1 and R2 are each methylene groupings within a common five- or six-membered saturated heterocyclic ring, Z is a methylene group when R4 is a hydrogen atom or an acyl radical containing up to 15 carbon atoms, or Z is a carbonyl group when R4 is a hydrogen atom, and X is a univalent anion or an equivalent of a multivalent anion. The preferred quaternary ammonium compound is choline chloride. The presence of the quaternary ammonium compound in the solution or dispersions reduces the amount of amine sulfate to about 0.25 to 2.5% required to achieve the desired film properties, the total concentration of the amine sulfate and additional additive within the range of up to 60%.