Transparent thermoplastic film and a method of producing the same

• US 8,043,714 B2
• Filed: 04/12/2007
• Issued: 10/25/2011
• Est. Priority Date: 04/13/2006
• Status: Expired due to Fees

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Hashimoto, Kiyokazu
• Primary Examiner(s): Kiliman; Leszek
• Application Number:
  US11/783,864
• Publication Number:
  US 20070275183A1
• Time in Patent Office: 1,657 Days
• Field of Search: 428/141, 428/532, 264/288.4, 264/290.2
• US Class Current: 428/532
• CPC Class Codes: B29C 55/06 parallel with the direction of feed
• CPC Class Codes: B29C 55/08 transverse to the direction of feed
• CPC Class Codes: B29C 55/143 firstly parallel to the direction of feed and then transversely thereto
• CPC Class Codes: B29C 55/20 Edge clamps
• CPC Class Codes: B29K 2001/00 Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
• CPC Class Codes: B29K 2001/12 Cellulose acetate
• CPC Class Codes: B29K 2023/38 Polymers of cycloalkenes, e.g. norbornene or cyclopentene
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/31971 Of carbohydrate

Abstract

A method of producing a transparent thermoplastic film comprising transversely stretching a film by 1% to 200%, wherein a ratio (Lc/Wc) of a clutch length (Lc) of a chuck to a clutch depth (Wc) of the chuck in the transverse stretching zone is in the range of 3 to 50.

Claims

1. A method of producing a transparent thermoplastic film comprising transversely stretching a film by 1% to 200%, wherein a ratio (Lc/Wc) of a clutch length (Lc) of a chuck to a clutch depth (Wc) of the chuck in the transverse stretching zone is in the range of 3 to 50,

wherein the transparent thermoplastic film has in-plane retardation (Re) in the range of from 20 to 400 nm, a thermal expansion distribution of 10% or less, and an optical elasticity modulus distribution of 10% or less in a square having one side of 30 cm.

2. The method of producing a transparent thermoplastic film according to claim 1, wherein a temperature of the chuck at the time of clutching is in the range of from 60°

C. to 200°

C.

3. The method of producing a transparent thermoplastic film according to claim 1, wherein a ratio (V¹/V²) of a chuck transporting speed (V¹) in the transverse stretching zone to a taking-up speed (V²) after the transverse stretching is in the range of from 1.001 to 1.1.

4. The method of producing a transparent thermoplastic film according to claim 1, comprising heat-treating the firm after the transverse stretching at a temperature in the range of (T¹ −

50)°

C. to (T¹ −

2)°

C., in which T¹ represents the transverse stretching temperature.

5. The method of producing a transparent thermoplastic film according to claim 1, wherein the film is heat-treated at a temperature in the range of from (T¹ +2)°

C. to (T¹ +50)°

C. before the transverse stretching, in which T¹ represents the transverse stretching temperature.

6. The method of producing a transparent thermoplastic film according to claim 1, comprising longitudinally stretching the film by 1 to 100%, in which the ratio of length/width (L/W) is in the range of above 0.01 to below 0.3 or above 2 to 50 or less.

7. The method of producing a transparent thermoplastic film according to claim 1, wherein the film at least one of after the transverse stretching and after other stretching is relaxed to give the total measure of relaxation in a length direction and a width direction of 1 to 20%, within the temperature range of (Tg −

30)°

C. to (Tg +30)°

C., in which Tg is a glass translation temperature of the transparent thermoplastic film.

8. The method of producing a transparent thermoplastic film according to claim 1, wherein the film is melt-formed by using a touch roll.

9. A transparent thermoplastic film having in-plane retardation (Re) in the range of from 20 to 400 nm, a thermal expansion distribution of 10% or less and an optical elasticity modulus distribution of 10% or less in a square having one side of 30 cm, wherein the film is transversely stretched by 1% to 200% within a ratio (Lc/Wc) of a clutch length (Lc) of a chuck to a clutch depth (Wc) of the chuck in a transverse stretching zone of the range of from 3 to 50.

10. The transparent thermoplastic film according to claim 9, in which an orientation angle distribution over the entire film-forming width area is in the range of from 0 °

±

5°

or 90 °

±

5 °

.

11. The transparent thermoplastic film according to claim 9, in which retardation (Rth) in the thickness direction is in the range of from 50 to 400 nm.

12. The transparent thermoplastic film according to claim 9, comprising cellulose acylate satisfying the following formulae

2.0≦

A+B<

3.0

0.1≦

B<

3

wherein A is a substitution degree of an acetate group and B is a total substitution degree of a propionate group, a butyrate group and a pentanoyl group.

13. The transparent thermoplastic film according to claim 9, which contains cellulose acylate satisfying the following formulae (T-1) and (T-2):

2.5≦

A+C≦

3.0 and  

 

Formula (T-1)

0.1≦

C<

2. 

 

Formula (T-2)

wherein, A indicates a substitution degree of an acetate group and C indicates a substituted or unsubstituted aromatic acyl group.

14. The transparent thermoplastic film according to claim 9, which contains a saturated norbornene resin.

15. The transparent thermoplastic film according to claim 9, wherein elasticity modulus is 2.9 kN/mm²or less.

16. The transparent thermoplastic film according to claim 9, wherein the number of luminescent spots having at least one side of 10 μ

m or more is 25/cm² or less, as observed when the transparent thermoplastic film is placed between two polarization plates disposed in a crossed Nicol state.

17. The transparent thermoplastic film according to claim 9, wherein a remaining solvent is 0.5% by mass or more.