Method for manufacturing thermoplastic sheets bearing embossed patterns thereon and an apparatus therefor

Abstract

Provided is a method for manufacturing a thermoplastic resin sheet bearing an embossed pattern, which employs a manufacturing apparatus having a first roll having an elastic material coated surface, a mirror-faced metal, endless belt, which is wound around the first roll and a second roll, and a third roll so provided that the metal, endless belt is wrapped partially around the third roll, which contacts the first roll via the metal, endless belt and which has an embossed pattern formed on one surface. According to this method, the thermoplastic resin sheet, partially melted, is fed between the metal, endless belt, which contacts the first roll, and the third roll. The elastic member is elastically deformed by application of a pressing force between the first and the third roll, while face pressure welding the thermoplastic sheet by using the first and the third rolls to transfer the embossed pattern and to cool the thermoplastic resin sheet. A surface temperature for the third roll of from 0° C. to (resin's Tg +20)°C. is maintained when the thermoplastic resin sheet is formed of an amorphous resin, and a surface temperature for the third roll of 0° C. to (resin's m.p. −30)°C. is maintained when the thermoplastic resin sheet is formed of a crystalline resin. Subsequently, face pressure welding of the thermoplastic resin sheet is performed by using the metal, endless belt relative to the third roll.

What is claimed is:  
     
       1. A method of manufacturing an amorphous thermoplastic resin sheet having an embossed pattern comprising the steps of: 
       providing a manufacturing apparatus comprising a first roll having an outer surface coated with an elastic material, a second roll, a third roll having an embossed pattern provided on an outer surface thereof and a metal endless belt having a mirror-finished surface wound around said first and second rolls and in contact with said third roll;  
       feeding the amorphous thermoplastic resin sheet, in a partially molten state, between the metal endless belt and the third roll;  
       maintaining the outer surface temperature of the third roll of from 0° C. to the amorphous thermoplastic resin's Tg;  
       elastically deforming the elastic material by applying a pressing force between said first and third rolls to conduct face pressure welding of said amorphous thermoplastic resin sheet and cool and transfer the embossed pattern to the amorphous thermoplastic resin sheet; and  
       performing face pressure welding of the amorphous thermoplastic resin sheet having the embossed pattern thereon between the metal endless belt and the third roll.  
     
     
       2. A method of manufacturing a crystalline thermoplastic resin sheet having an embossed pattern comprising the steps of: 
       providing a manufacturing apparatus comprising a first roll having an outer surface coated with an elastic material, a second roll, a third roll having an embossed pattern provided on an outer surface thereof and a metal endless belt having a mirror-finished surface wound around said first and second rolls and in contact with said third roll;  
       feeding the crystalline thermoplastic resin sheet, in a partially molten state, between the metal endless belt and the third roll;  
       maintaining the outer surface temperature of the third roll of from 0° C. to the crystalline thermoplastic resin's m.p. −30° C.;  
       elastically deforming the elastic material by applying a pressing force of from 0.1-20 MPa between said first and third rolls to conduct face pressure welding of said crystalline thermoplastic resin sheet and cool and transfer the embossed pattern to the crystalline thermoplastic resin sheet; and  
       performing face pressure welding of the crystalline thermoplastic resin sheet having the embossed pattern thereon between the metal endless belt and the third roll at a pressure of from 0.1  0.01-0.5 MPa.  
     
     
       3. A method for manufacturing a crystalline thermoplastic resin sheet bearing an embossed pattern according to  claim 2 , wherein, said surface temperature of said third roll is between zero and the resin's m.p. −50° C. 
     
     
       4. A method for manufacturing an amorphous thermoplastic resin sheet bearing an embossed pattern according to  claim 1 , wherein the pressure during said face pressure welding of said thermoplastic resin sheet is 0.1 MPa to 20.0 MPa, and wherein said pressure during said face pressure welding of said thermoplastic resin sheet having the embossed pattern thereon is from 0.1  0.01 to 0.5 MPa. 
     
     
       5. A method for manufacturing an amorphous thermoplastic resin sheet bearing an embossed pattern according to  claim 1 , wherein the surface roughness of the mirror-finished surface of said metal endless belt is 3 S or lower. 
     
     
       6. A method for manufacturing a crystalline thermoplastic resin sheet bearing an embossed pattern according to  claim 2 , wherein the surface roughness of the mirror-finished surface of said metal endless belt is 3 S or lower.