Method of producing sheet made of a low-viscosity polyester resin
AssigneeOsaka Chemical Co., Ltd.
InventorShinji Ishikawa
Life of this patent
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Abstract
Polyester sheets are produced by melting a low-viscosity polyester such as a recovered polyester under reduced pressure, extruding the melt into a sheet, and stretching the sheet in the direction of width by 2.5 to 120%. The polyester resin of the oriented sheet thus obtained has an intrinsic viscosity of 0.40 to 0.63. Polyester sheets can be produced readily and continuously from recovered polyester resins or polyester resins below standards, which have a low intrinsic viscosity, and the cost of production of polyester sheets is reduced. These sheets can be formed into various shaped articles by vacuum forming, pressure forming or the like without occurrence of draw-down and without giving defective shaped articles.
Claims10
A method of producing low-viscosity polyester resin sheets which comprises melting a polyester resin with an intrinsic viscosity of 0.45 to 0.70 under reduced pressure extruding the melt into a sheet and stretching said sheet in a direction perpendicular to the direction of progression of said sheet.
Dependencies are inferred from the claim text.