Manufacture of polymeric products
AssigneeW. R. Grace & Co.-Conn.
InventorsFrancesco Martini, Luigi Perazzo, Paolo Vietto
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Abstract
HB polymers, such as copolymers of hydroxy butyric acid and hydroxy valeric acid, are provided as melt extruded films having a thickness of 5 to 200 .mu.m. Sheet materials may consist of such a film or the film may be laminated with other films to increase strength or impermeability. The films are best made by co-extrusion with a thermoplastic that is substantially non-tacky upon solidification. The sheet materials are of particular value as diaper backsheets and ostomy bags. They may include a layer of non-woven material.
Claims4
A method of making a sheet material comprising melt extruding a laminated tube of a tubular layer of HB polymer composition in molten form and a tubular layer of molten thermoplastic that is substantially non-tacky on solidification, and stretching and solidifying the extruded laminate, wherein the HB polymer is a biodegradable polymer formed of recurring units of which 50 to 100% molar are units of formula 1
- --OC.sub.n H.sub.2n CO--
- where n is 3, 4 or 5 and the HB polymer composition comprises 50 to 100% of the HB polymer and 0 to 50% diluent additive, the layer of HB polymer composition is to a thickness of 5 to 200 um and the layer of HB polymer composition has moisture vapor transmission of 30 to 200 g/25 um.m.sup.2.day at 38.degree. C. and has an oxygen transmission value of 10 to 200 cc/25 um.m.sup.2.day.bar at 23.degree. C.
Dependencies are inferred from the claim text.