Patent ID: 6306327
Filing Date: 2001-10-23
Classification: B29C

Abstract:
A method of producing a thermoplastic resin sheet, using a producing apparatus in which a metallic endless belt having a mirror face on a surface thereof is wound on and extends between a first endless belt supporting cooling roller covered with an elastic member and a second endless belt supporting cooling roller spaced from the first cooling roller, and a third cooling roller having a mirror face on a surface thereof and capable of applying pressure to the first cooling roller through a molten thermoplastic resin sheet and the metallic endless belt to hold the molten thermoplastic resin sheet pressed against the metallic endless belt are provided, the method comprising the steps of:guiding the molten thermoplastic resin sheet into an area between the first endless belt supporting cooling roller and the third cooling roller to approximately simultaneously touch the metallic endless belt and the belt and the third cooling roller;compressing the resin sheet between the first endless belt supporting cooling roller and the third cooling roller while the temperature of the metallic endless belt, directly touching the molten thermoplastic resin sheet and the third cooling roller touching the molten resin sheet is retained at less than 50.degree. C., while touch-rolling the face and cooling the molten thermoplastic resin sheet along a nip width of at least 5 mm between the first endless belt cooling roller and the third cooling roller while the elastic member is elastically deformed by a compressing force between the first endless belt cooling roller and the third cooling roller; andcooling, subsequently, the molten thermoplastic resin sheet by the touch-rolling on the face of the metallic endless belt against the third cooling roller to cool the molten resin sheet to a temperature less than 50.degree. C. before the sheet leaves the surface of the third cooling roller;wherein when the molten thermoplastic resin sheet is touch-rolled on the face of the endless belt with the elastic deformation of the elastic member, the face pressure is defined as 0.1 MPa-20.0 MPa; andwherein when the molten thermoplastic resin sheet travels downstream from the first cooling roller, the resin sheet is touch-rolled on the face of the endless belt between only the third cooling roller and the endless belt, with the face pressure defined as 0.01 MPa-0.5 MPa.