Biaxially oriented polyester film and production method thereof

• US 6,420,011 B1
• Filed: 09/10/1999
• Issued: 07/16/2002
• Est. Priority Date: 09/11/1998
• Status: Expired due to Term

• Current Assignee: Toray Industries Incorporated
• Original Assignee: Toray Industries Incorporated
• Inventors: Higashioji, Takuji, Hosokawa, Hirofumi, Tsunekawa, Tetsuya
• Primary Examiner(s): Copenheaver, Blaine
• Assistant Examiner(s): CHEVALIER, ALICIA ANN
• Application Number:
  US09/393,819
• Time in Patent Office: 1,040 Days
• Field of Search: 428/141, 428/213, 428/215, 428/480, 428/473.5, 428/910, 525/432
• US Class Current: 428/141
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 2379/08 Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 67/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: C08L 79/08 Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: G11B 5/73931 Two or more layers, at least one layer being polyester
• CPC Class Codes: G11B 5/73935 characterised by roughness or surface features, e.g. by added particles
• CPC Class Codes: Y10S 428/91 Product with molecular orientation
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/31721 Of polyimide
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

The objects of the present invention can be achieved by a biaxially oriented polyester film, comprising a polyester (A) mainly composed of ethylene terephthalate and a polyether imide (B), having a single glass transition temperature, and having a refractive index of 1.60 to 1.80 at least in either the machine direction or the transverse direction.

Claims

1. A biaxially oriented polyester film, comprising a polyester (A) mainly composed of ethylene terephthalate and a polyether imide (B), having a single glass transition temperature, and having a refractive index of 1.60 to 1.80 at least in either the machine direction or the transverse direction.

2. A biaxially oriented polyester film, according to claim 1, which has a density of 1.35 to 1.42 g/cm³.

3. A biaxially oriented polyester film, according to claim 1, which has a face orientation factor of 0.03 to less than 0.19.

4. A biaxially oriented polyester film, according to claim 1, which has an extrapolated glass transition onset temperature (Tg-onset) of 90 to 150°

C.

5. A biaxially oriented polyester;

film, according to claim 1, wherein the heat of crystal fusion Δ

H obtained from DSC is 15 to 45 J/g.

6. A biaxially oriented polyester film, according to claim 1, wherein the number of coarse protrusions with a protrusion height of 0.5 μ

m or more on the surface is less than 30/100 cm².

7. A biaxially oriented polyester film, according to claim 1, wherein the haze as a 25 μ

m film 0.1 to 15%.

8. A biaxially oriented polyester film, according to claim 1, wherein the polyether imide (B) content is 1 to 50%.

9. A biaxially oriented polyester film, according to claim 1, which has an inherent viscosity of 0.55 to 2.0 dl/g.

10. A biaxially oriented polyester film, according to claim 1, wherein the sum (Y_MD+Y_TD) of the Young'"'"'s modulus in the machine direction (Y_MD) and the Young'"'"'s modulus in the transverse direction (Y_TD) is 8 to 25 GPa.

11. A biaxially oriented polyester film, according to claim 1, wherein the creep compliance after lapse of 30 minutes at 50°

C. and at a load of 28 MPa is 0.10 to 0.55 GPa<sup>−

1</sup>.

12. A biaxially oriented polyester film, according to claim 1, wherein the 100°

C. heat shrinkage at least in either the machine direction or the transverse direction is 1% or less.

13. A biaxially oriented polyester film, according to claim 1, which has a thickness variation of less than 15%.

14. A biaxially oriented polyester film, according to claim 1, which has a thickness of 0.5 μ

m to 300 μ

m.

15. A magnetic recording medium, comprising biaxially oriented polyester film according to claim 1.

16. A capacitor, comprising the biaxially oriented polyester film according to claim 1.

17. A thermal transfer ribbon, comprising the biaxially oriented polyester film according to claim 1.

18. A heat-sensitive mimeograph stencil, comprising the biaxially oriented polyester film according to claim 1.