Polyester composition, polyester film, and magnetic recording medium

Patent metadata

Field	Value
Publication number	US-11739182-B2
Application number	US-201916964120-A
Country	US
Kind code	B2
Filing date	Jan 23, 2019
Priority date	Jan 31, 2018
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

An object of the present invention is to more conveniently provide a copolyester for a polyester film which exhibits excellent dimensional stability and in particular excellent dimensional stability against environmental changes in, for example, temperature and humidity, and has a small film elongation percentage at 110° C. A copolyester of the present invention comprises: (A) an aromatic dicarboxylic acid component; (B) an alkylene glycol component; and (C1) a dimer acid component and/or (C2) a dimer diol component, wherein the copolyester contains, with reference to a molar number of a total dicarboxylic acid component, 0.5 to 3.5 mol % of the dimer acid component (C1) and/or 0.3 to 5.0 mol % of the dimer diol component (C2).

First claim

The invention claimed is:

1. A copolyester comprising:
(A) an aromatic dicarboxylic acid component;
(B) an alkylene glycol component; and
(C1) a dimer acid component and/or (C2) a dimer diol component,
wherein the copolyester contains, with reference to a molar number of a total dicarboxylic acid component, 0.5 to 3.5 mol % of the dimer acid component (C1) and/or 0.3 to 4.0 mol % of the dimer diol component (C2), and wherein the dimer acid component (C1) and/or the dimer diol component (C2) has an average carbon number of at least 20.

2. The copolyester according to claim 1 , wherein the dimer acid component (C1) and/or the dimer diol component (C2) are/is derived from a mixture of an aliphatic dicarboxylic acid component and/or aliphatic diol component having an average carbon number of 20 to 55.

3. The copolyester according to claim 1 , comprising repeating units (I) to (III):
—C(O)—R A —C(O)—  (I)

—C(O)—R B —C(O)—  (II)

—O—R C —O—  (III)

wherein the repeating unit (I) is the dimer acid component (C1), and R A is an alkylene group which has 31 to 51 carbon atoms, and may contain a cyclo ring and/or a branched chain,
the repeating unit (II) is the aromatic dicarboxylic acid component (A), and R B is a phenylene group or a naphthalenediyl group, and
the repeating unit (III) is the alkylene glycol component (B), and R C is an alkylene group having 2 to 6 carbon atoms.

4. The copolyester according to claim 1 , wherein
the copolyester contains, with reference to a molar number of the aromatic dicarboxylic acid component, 0.3 to 4.0 mol % of the dimer diol component (C2),
the aromatic dicarboxylic acid component (A) is aromatic dicarboxylic acid having 6 or more carbon atoms,
the alkylene glycol component (B) is alkylene glycol having 2 to 4 carbon atoms, and
the dimer diol component (C2) is aliphatic dimer diol having 31 to 50 carbon atoms.

5. The copolyester according to claim 1 , wherein
the copolyester comprises the dimer diol component (C2), and
the dimer diol component (C2) comprises a branched chain and/or a cyclohexane ring structure.

6. A polyester film comprising the copolyester according to claim 1 .

7. The polyester film according to claim 6 , wherein the polyester film has a temperature expansion coefficient of 14 ppm/° C. or less in at least one direction in the plane direction of the polyester film.

8. The polyester film according to claim 6 , wherein the polyester film has a humidity expansion coefficient of 1 to 8.5 ppm/% RH in at least one direction in the plane direction of the polyester film.

9. A laminated polyester film comprising:
a film layer A which comprises a polyester film; and
a film layer B which comprises a polyester film and is laminated over the film layer A,
wherein at least one of the film layer A and the film layer B is the polyester film according to claim 6 .

10. The laminated polyester film according to claim 9 , wherein a content (W AB ) of the dimer acid component (C1) is within a range of 0.5 to 3.5 mol % or a content (W AB ) of the dimer diol component (C2) is within a range of 0.5 to 5.0 mol %, with reference to a molar number of a total dicarboxylic acid component in a whole of the laminated polyester film.

11. The laminated polyester film according to claim 9 , wherein a difference between a content (W A ) of the dimer acid with reference to a molar number of a total dicarboxylic acid component in the film layer A and a content (W B ) of the dimer acid with reference to a molar number of a total dicarboxylic acid component in the film layer B is 0.3 mol % or more.

12. The laminated polyester film according to claim 9 , wherein a difference between a content (W A ) of the dimer diol with reference to a molar number of a total dicarboxylic acid component in the film layer A and a content (W B ) of the dimer diol with reference to a molar number of a total dicarboxylic acid component in the film layer B is 0.3 mol % or more.

13. The laminated polyester film according to claim 9 , wherein a difference between surface roughness (Ra A ) of the film layer A and surface roughness (Ra B ) of the film layer B is 1.0 nm or more.

14. The laminated polyester film according to claim 9 , wherein at least one film layer of the film layers A and B contains, with reference to a mass of the film layer, 0.5 to 25% by mass of at least one selected from the group consisting of polyimide, polyether imide, polyether ketone, polyether ether ketone, and a mixture thereof in addition to the copolyester.

15. The laminated polyester film according to claim 9 , wherein the laminated polyester film is used for a base film of a magnetic recording medium.

16. A magnetic recording medium comprising:
the laminated polyester film according to claim 9 ; and
a magnetic layer formed on one surface of the laminated polyester film.

17. The laminated polyester film according to claim 9 , wherein a ratio (dA/dB) of a thickness (dA) of the film layer A and a thickness (dB) of the film layer B is 0.03 to 33.

18. The laminated polyester film according to claim 9 , wherein the laminated polyester film has a temperature expansion coefficient of 14 ppm/° C. or less in at least one direction in the plane direction of the laminated polyester film.

19. The laminated polyester film according to claim 9 , wherein the laminated polyester film has a humidity expansion coefficient of 1 to 8.5 ppm/% RH in at least one direction in the plane direction of the laminated polyester film.

Assignees

• Toyobo Film Solutions Ltd
• Toyo Boseki

Inventors

• Hirose Amane
• Handa Makoto
• Tojo Mitsuo
• Ogawa Tatsuya

Classifications

• C08G63/181 Primary

  Acids containing aromatic rings · CPC title

• B32B27/08

  of synthetic resin · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title

• G11B5/73931

  Two or more layers, at least one layer being polyester · CPC title

• B32B2250/02

  2 layers · CPC title