Biaxially oriented polyester film

Patent metadata

Field	Value
Publication number	US-11186701-B2
Application number	US-202017006015-A
Country	US
Kind code	B2
Filing date	Aug 28, 2020
Priority date	Sep 2, 2019
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A biaxially oriented polyester film, which exhibits an excellent winding property in a manufacturing process, and realizes an excellent electromagnetic conversion property and less failure of signals of a magnetic recording tape to be produced thereof, is provided. This biaxially oriented polyester film satisfies the formula y≤−24.9X+3.8, where the protrusion height X is 0.075 μm, 0.100 μm, and 0.125 μm, and y denotes a base-10 logarithm value of the number of protrusions having protrusion heights of X or more in a visual field of a region of 282 μm×211 μm, and a protrusion height that corresponds to a 0.4% area of a bearing curve based on protrusion height distribution is 65-90 nm.

First claim

What is claimed is:

1. A biaxially oriented polyester film, wherein a logarithm value y of a protrusion frequency of protrusions having protrusion heights of X or more on at least one surface, which is measured by a contactless surface shape measurement device, satisfies a below relation formula (1), where the protrusion height X is 0.075 μm, 0.100 μm and 0.125 μm,
y≤− 24.9 X+ 3.8  (1)

(herein, X denotes a protrusion height (μm), y denotes a base-10 logarithm value of a protrusion number of protrusions having protrusion heights of X or more in a visual field of a region of 282 μm×211 μm), and
a protrusion height that corresponds to a 0.4% area of a bearing curve based on protrusion height distribution is 65 nm or more and less than 90 nm.

2. The biaxially oriented polyester film according to claim 1 , wherein polyester contained in the biaxially oriented polyester film has ethylene terephthalate or ethylene-2,6-naphthalenedicarboxylate as a main repeating unit.

3. The biaxially oriented polyester film according to claim 1 , wherein, when measuring the one surface and an other surface of the biaxially oriented polyester film by a contactless surface shape measurement device, center line average surface roughness of the one of the surfaces is higher than center line average surface roughness of the other surface by 1 nm or more.

4. The biaxially oriented polyester film according to claim 3 , comprising inert particles.

5. The biaxially oriented polyester film according to claim 3 , comprising two or more layers of different polyester layers laminated.

6. The biaxially oriented polyester film according to claim 1 , comprising inert particles.

7. The biaxially oriented polyester film according to claim 6 , comprising two or more layers of different polyester layers laminated.

8. The biaxially oriented polyester film according to claim 1 , comprising two or more layers of different polyester layers laminated.

Assignees

• Toyobo Film Solutions Ltd
• Toyo Boseki

Inventors

• Handa Makoto
• Muro Shinji

Classifications

• G11B5/66

  the record carriers consisting of several layers · CPC title

• C08G63/183

  Terephthalic acids · CPC title

• B32B27/36

  comprising polyesters · CPC title

• B32B2307/518

  bi-axially · CPC title

• B32B2307/732

  Dimensional properties · CPC title