| abstract |
Improvements in the preparation of organic multilayer polymer composites, especially useful for composites including adjacent layers of a relatively water-soluble polymer (e.g., partially hydrolyzed polyvinyl alcohol) and a relatively water-insoluble polymer (e.g., a fully hydrolyzed polyvinyl alcohol). The extruded layers are brought together inside the cover or by a press device outside the nozzle, or the relatively water-insoluble layer can be coated on the relatively water-soluble layer. Specific designs of the nozzle are required, as are specific extrudable compositions and apparatus for transporting them to the nozzles. The invention provides, for the first time, a selection of articles where the plastic parts are water-compatible under normal use, but are completely degradable upon contact with water when disposed of, such as sanitary articles thrown into the WC, and water-degradable rigid containers for oil or gasoline. |