A composite board is produced by the method of blending a cellulosic filler having sufficient extractable organic content and an expandable thermoplastic polymer, adding a tacifier agent during blending for producing a pre-blown mixture, heating the mixture in a mold to a temperature above the glass...http://www.google.es/patents/US4818604?utm_source=gb-gplus-sharePatente US4818604 - Composite board and method
