| 摘要 |
<p>A packaging film which is permeable to smoke constituents is made from a thermoplastic copolyester. The copolyester is built up of recurrent long-chain and short-chain ester units which are joined head-to-tail through ester bonds, the long-chain ester units corresponding to the formula <IMAGE> and the short-chain ester units to the formula: <IMAGE> where R1 is a divalent radical remaining after removal of the terminal hydroxyl groups from a poly(alkylene oxide) glycol having a molecular weight in the range of 600 to 6000 and a carbon to oxygen ratio of 2,0 to 2,7; R2 is a divalent radical remaining after removal of the hydroxyl groups from a diol having a molecular weight not higher than 250; R3 is a divalent radical remaining after removal of the carboxylic acid groups from a dicarboxylic acid. Said long-chain ester units amount to 20 to 60% by weight of the copolyester and at least 70% of the R3 groups are 1,4-phenylene radicals. The phenol number of the film, expressed in mg per m2, is at least 20. The film is particularly suitable for packaging foodstuffs that are smoked in the packaged state, such as smoked sausages.</p> |
