| 摘要 |
Composite polymeric articles, which may be in layer or film form, comprise a larger portion of a polymer which is water- soluble at 20 .degree. C against a smaller proportion of a polymer which is substantially water-insoluble at that temperature. For exam- ple, a layer product may have a thin layer (e.g. less than 5.mu.m) of insoluble polymer superimposed on a thicker layer (e.g. at least 20.mu.m) of soluble polymer. Both polymers are conveniently polyvinyl alcoho l, which is non-toxic and useful in a number of dom- estic applications e.g. as a nappy backing sheet. The insoluble portion give s water resistance but negligible mechanical strength; the soluble part gives the mechanical strength. On dissolution of the solubl e portion, the insoluble portion disintegrates mechani- cally. Articles may be made by co-extrusion or by moulding.
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