Process for producing thermoplastic resin sheet with controlled warpage

Abstract

The present invention provides a process for producing a thermoplastic resin sheet with controlled warpage, the process including extruding a thermoplastic resin sheet, while giving mechanically controlled warpage to the sheet at a position where a temperature of the sheet extruded becomes around a grass transition temperature (Tg) of a thermoplastic resin constituting the sheet. In this production process, the sheet is preferably allowed to pass through a pair of warpage-controlling upper and lower rolls at the position, and the mechanically controlled warpage is preferably given to the sheet by selecting shapes of the warpage-controlling rolls and/or by disposing the warpage-controlling rolls on an upper side or a lower side of a height where a flat sheet is obtained. According to this production process, a thermoplastic resin sheet with controlled warpage can be produced simply and easily with high efficiency.

1 . A process for producing a thermoplastic resin sheet with controlled warpage, the process comprising extruding a thermoplastic resin sheet, while giving mechanically controlled warpage to the sheet at a position where a temperature of the extruded sheet becomes around a grass transition temperature (Tg) of a thermoplastic resin constituting the sheet.  
   
   
       2 . The production process according to  claim 1 , wherein the sheet is allowed to pass through a pair of warpage-controlling upper and lower rolls at the position, and the mechanically controlled warpage is given to the sheet by selecting shapes of the warpage-controlling rolls and/or by disposing the warpage-controlling rolls on an upper side or a lower side of a height where a flat sheet is obtained.  
   
   
       3 . The production process according to  claim 2 , wherein the temperature of the sheet at a position of the warpage-controlling rolls is within a range of from (Tg−20° C.) to (Tg+20°).  
   
   
       4 . The production process of  claim 2 , wherein thermally controlled warpage is also given to the sheet by adjusting respective temperatures of the warpage-controlling rolls to generate a difference in cooling rates between upper and lower surfaces of the sheet.  
   
   
       5 . The production process according to  claim 2 , wherein thermally controlled warpage is also given to the sheet by adjusting a difference in temperatures between upper and lower surfaces of the sheet at a position or in a vicinity of the warpage-controlling rolls to generate a difference in cooling rates between the upper and lower surfaces of the sheet.  
   
   
       6 . The production process according to  claim 1 , wherein the thermoplastic resin constituting the sheet comprises fine particles.  
   
   
       7 . The production process according to  claim 1 , wherein the thermoplastic resin constituting the sheet is selected from the group consisting of polycarbonate resins, (meth)acrylic resins, styrene resins, acryl-styrene resins, and norbornene resins.  
   
   
       8 . A thermoplastic resin sheet with controlled warpage, which is obtainable by the production process according to  claim 1.