Polyester film having low electrostatic and high adhesion properties

• US 5,811,197 A
• Filed: 03/17/1997
• Issued: 09/22/1998
• Est. Priority Date: 03/21/1996
• Status: Expired due to Term

• Current Assignee: Teijin Limited
• Original Assignee: Teijin Limited
• Inventors: Handa, Makoto, Osawa, Toshifumi, Watanabe, Hideaki, Nishiyama, Masanori
• Primary Examiner(s): Mosley, Terressa
• Application Number:
  US08/818,450
• Time in Patent Office: 554 Days
• Field of Search: 528/176, 428/480
• US Class Current: 428/480
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 2467/00 Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain of polyester-amides C08J2477/12; of polyester-imides C08J2479/08; Derivatives of such polymers
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: C08L 71/00 Compositions of polyethers obtained by reactions forming an ether link in the main chain of polyacetals C08L59/00; of epoxy resins C08L63/00; of polythioether-ethers C08L81/02; of polyether-sulfones C08L81/06; Compositions of derivatives of such polymers
• CPC Class Codes: C09D 167/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C09D167/06 takes precedence
• CPC Class Codes: G11B 5/73 Base layers , i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
• CPC Class Codes: G11B 5/73927 Polyester substrates, e.g. polyethylene terephthalate
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

A polyester film having low electrostatic and high adhesion properties and having formed on at least one side thereof a primer layer which has a softening point of 100° to 170° C. and essentially consists of (1) water-dispersible polyester resin containing, as a copolymer component, a sulfonic acid metal salt group-containing compound in an amount of 0.01 mol % or more and less than 0.5 mol % of the whole dicarboxylic acid compound (component A) and (2) polyethylene oxide-monoalkyl ether or a mixture of the same and a polyethylene oxide-polypropylene oxide block copolymer (component B). This adherent polyester film has low electrostatic properties and high heat resistance and is useful as a base film for a magnetic recording medium.

Claims

1. A polyester film having low electrostatic and high adhesion properties and having formed on at least one side thereof a primer layer which has a softening point of 100°

to 170°

C. and consists essentially of component A and component B

wherein component A is a water-dispersible polyester resin containing, as a copolymer component, a sulfonic acid metal salt group-containing compound in an amount of 0.04 to 0.3 mol % of the whole dicarboxylic acid compound, and

wherein component B is

(i) a polyethylene oxide-monoalkyl ether, or

(ii) a mixture of a polyethylene oxide monoalkyl ether (i) and a polyethylene oxide-polypropylene oxide block copolymer

wherein the weight ratio of (i) to (ii) is 10;

0 to 2;

8.

2. The polyester film of claim 1, wherein the primer layer contains component A in an amount of 93 to 70% by weight and component B in an amount of 7 to 30% by weight.

3. The polyester film of claim 1, wherein the monoalkyl ether of component B-1 in the primer layer has 8 to 18 carbon atoms in its alkyl moiety.

4. The polyester film of claim 1 or 4, wherein component B-1 in the primer layer has 3 to 15 ethylene oxide recurring units.

5. The polyester film of claim 1, wherein the component B-2 in the primer layer is a block copolymer comprising polyethylene oxide units and polypropylene oxide units in a weight ratio of 50:

50 to 90;

10.

6. The polyester film of claim 1, wherein the component B-2 in the primer layer is a polyethylene oxide-polypropylene oxide block copolymer having a number average molecular weight of 5,000 to 30,000.

7. The polyester film of claim 1, wherein component A in the primer layer is a water-dispersible polyester resin containing a 2,6-naphthalenedicarboxylic acid component in an amount of 30 to 100 mol % of the whole dicarboxylic acid compound.

8. The polyester film of claim 1, wherein the primer layer has a thickness of 0.005 to 1 μ

m.

9. The polyester film of claim 1, wherein the primer layer has a center line average surface roughness (Ra) of 0.002 to 0.02 μ

m.

10. The polyester film of claim 1, wherein the polyester film has a thickness of 3 to 20 μ

m.

11. The polyester film of claim 1, wherein the primer layer consists of component A and component B-1, the proportion of component A is 93 to 70% by weight and proportion of component B is 7 to 30% by weight, and the running friction coefficient at the time of heating at 65°

C. and 105°

C. is 0.05 to 0.75.

12. The polyester film of claim 1, wherein the primer layer consists essentially of component A and component B-1, proportion of the component A is 90 to 75% by weight and the proportion of the component B-1 is 10 to 25% by weight, and the running friction coefficient at the time of heating at 65°

C. and 105°

C. is 0.10 to 0.65.

13. The polyester film of claim 1, wherein (i) the primer layer consists essentially of component A, component B-1 and the component B-2, the proportion of component A is 93 to 80 % by weight, the proportion of component B-1 is 10 to 2% by weight, and the proportion of component B-2 is 15 to 5% by weight, and (ii) the primer layer has a softening point of 140°

to 170°

C.

14. The polyester film of claim 1, wherein (i) the primer layer consists essentially of component A, component B-1 and component B-2, the proportion of component A is 90 to 80% by weight, the proportion of component B-1 is 7 to 3% by weight, and the proportion of component B-2 is 13 to 7% by weight, and (ii) the primer layer has a softening point of 146°

to 165°

C.

15. The polyester film of claim 1 for use as a base film for a magnetic recording medium.