Breathable, heat-sealable composite polymeric film

摘要

A breathable, heat-sealable composite film comprising first and second layers of polymeric material wherein (i) the polymeric material of the first layer comprises copolyester comprising monomeric units derived from one or more diol(s); one or more dicarboxylic acid(s); and one or more poly(alkylene oxide)glycol(s); and (ii) the second layer is a heat-sealable polymeric layer, and a process for the production thereof.

主权项

1. A breathable, heat-sealable composite film comprising first and second layers of polymeric material wherein:
(i) the polymeric material of the first layer comprises a copolyester comprising monomeric units derived from one or more diol(s); one or more dicarboxylic acid(s), wherein at least one of said one or more dicarboxylic acids is an aromatic acid; and one or more poly(alkylene oxide)glycol(s); (ii) the second layer is a heat-sealable polymeric layer; (iii) the composite film has an elongation to break of less than 250%; (iv) the poly(alkylene oxide)glycol of the first layer constitutes in the range of 10 to 40 mol % of all diol and glycol monomeric units of the first layer; wherein the polymeric material of the first layer comprises greater than 50% of the copolyester by weight, relative to the total amount of polymeric material in the first layer, and wherein the heat-sealable polymeric layer is formed by coating the heat-sealable polymer onto the first layer, conducted after the first layer is stretched and subsequently heat-set; and wherein: (a) the copolyester of the first layer has a glass transition temperature (Tg) of at least 0° C. and no more than 60° C.; or (b) the polymeric material of the heat-sealable second layer is derived from a first aromatic dicarboxylic acid, a low molecular weight aliphatic diol, a poly(alkylene oxide)glycol, and a further dicarboxylic acid which imparts heat-sealability.