Biaxially stretched polyester film and method for producing same, and optical sheet

Patent metadata

Field	Value
Publication number	US-2016130415-A1
Application number	US-201615001253-A
Country	US
Kind code	A1
Filing date	Jan 20, 2016
Priority date	Jul 23, 2013
Publication date	May 12, 2016
Grant date	—

Abstract

Disclosed is a biaxially stretched polyester film containing an antimony compound as a catalyst component, and a magnesium compound and a phosphorus compound as additives, in which an amount of metal antimony included in residues on a membrane filter having an average pore diameter of 0.1 μm, after a solution in which 1 g of the biaxially stretched polyester is dissolved in 5 ml of hexafluoroisopropanol is filtered by the filter, is greater than 1 mg per 1 kg and less than or equal to 100 mg per 1 kg of the biaxially stretched polyester.

First claim

What is claimed is:

1 . A biaxially stretched polyester film containing an antimony compound as a catalyst component, and a magnesium compound and a phosphorus compound as additives,
wherein an amount of metal antimony included in residues on a membrane filter having an average pore diameter of 0.1 μm, after a solution in which 1 g of the biaxially stretched polyester is dissolved in 5 ml of hexafluoroisopropanol is filtered by the filter, is greater than 1 mg per 1 kg and less than or equal to 100 mg per 1 kg of the biaxially stretched polyester.

2 . The biaxially stretched polyester film according to claim 1 ,
wherein a micro heat absorption peak temperature Tmeta (° C.) of the biaxially stretched polyester film obtained by differential scanning calorimetry (DSC) satisfies the following Expression 1:
210° C.≦ T meta≦230° C.  (Expression 1).

3 . The biaxially stretched polyester film according to claim 1 ,
wherein the biaxially stretched polyester film contains diethylene glycol, and a content of the diethylene glycol is from 1.0 mol % to 1.5 mol %.

4 . The biaxially stretched polyester film according to claim 1 ,
wherein the biaxially stretched polyester film further satisfies a relationship denoted by the following Expression 2:
20 ppm≦ W P ≦W Mg ≦55 ppm  (Expression 2)

wherein in Expression 2, W P represents a content (ppm) of phosphorus in the biaxially stretched polyester film, and W Mg represents a content (ppm) of magnesium in the biaxially stretched polyester film.

5 . The biaxially stretched polyester film according to claim 1 ,
wherein the biaxially stretched polyester film is used in an optical sheet.

6 . A method for producing a biaxially stretched polyester film, the method comprising:
performing an esterification reaction through at least two series-connected esterification reactors including a first esterification reactor in which a magnesium compound is added to a composition including a dicarboxylic acid component, a diol component, and an antimony compound and a second esterification reactor which is arranged on a downstream side of the first esterification reactor and in which a phosphorus compound is added to the composition to which the magnesium compound has been added; performing a polycondensation reaction with respect to an esterification reaction product generated in the esterification reaction, through at least two polycondensation reactors including a first polycondensation reactor in which a pressure is less than or equal to 6.00×10 3 Pa and a second polycondensation reactor which is arranged on a downstream side of the first polycondensation reactor and in which a pressure is less than or equal to 0.60×10 3 Pa; forming a film by melting and extruding a polyester generated via at least the esterification reaction and the polycondensation reaction; vertically stretching a formed polyester film in a longitudinal direction; and horizontally stretching the vertically stretched polyester film.

7 . The method for producing a biaxially stretched polyester film according to claim 6 ,
wherein in the esterification reaction, the esterification reaction is performed by continuously moving the composition through at least two esterification reactors in sequence from the first esterification reactor.

8 . The method for producing a biaxially stretched polyester film according to claim 6 ,
wherein in the polycondensation reaction, the polycondensation reaction is performed by continuously moving the esterification reaction product obtained in the esterification reaction through at least two polycondensation reactors in sequence from the first polycondensation reactor.

9 . An optical sheet, comprising:
the biaxially stretched polyester film according to claim 1 ; and an easily adhesive layer which is disposed on at least one surface of the biaxially stretched polyester film, and contains at least one type of resin selected from a polyester resin, a urethane resin, an acrylic resin, or a melamine resin, in an amount of greater than or equal to 50 mass %.

Assignees

• Fujifilm Corp

Inventors

• Miyasaka Rei

Classifications

• B29K2267/00

  Use of polyesters {or derivatives thereof} as reinforcement · CPC title

• C09J2475/006

  in the substrate · CPC title

• C08J2367/02

  Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) · CPC title

• C08K5/521

  Esters of phosphoric acids, e.g. of H3PO4 · CPC title

• B29C47/0021

  Operations & Transport · mapped topic