| 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 DEG C against a smaller proportion of a polymer which is substantially water-insoluble at that temperature. For example, 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 alcohol, which is non-toxic and useful in a number of domestic applications e.g. as a nappy backing sheet. The insoluble portion gives water resistance but negligible mechanical strength; the soluble part gives the mechanical strength. On dissolution of the soluble portion, the insoluble portion disintegrates mechanically. Articles may be made by co-extrusion or by moulding. |
