METHOD FOR MANUFACTURING RETARDATION FILM, RETARDATION FILM, POLARIZING PLATE, AND LIQUID CRYSTAL DISPLAY

• US 20090195877A1
• Filed: 01/27/2009
• Published: 08/06/2009
• Est. Priority Date: 01/31/2008
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: NAKAI, Shinichi
• Granted Patent: US 8,120,849 B2
• Time in Patent Office: Days
• US Class Current: 359/489.07
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/387 using a screw extruder and a gear pump
• CPC Class Codes: B29C 48/53 having a varying channel depth, e.g. varying the diameter of the longitudinal screw trunk
• CPC Class Codes: B29C 48/69 Filters or screens for the moulding material
• CPC Class Codes: B29C 48/693 Substantially flat filters mounted at the end of an extruder screw perpendicular to the feed axis
• CPC Class Codes: B29C 48/914 cooling drums
• CPC Class Codes: B29C 48/9155 Pressure rollers
• 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: B29D 11/00634 Production of filters
• 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: B29K 2995/0032 Birefringent
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133635 Multifunctional compensators
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation

Abstract

A retardation film is manufactured by stretching a thermoplastic resin film while adjusting stretching ratio α [%], temperature β [° C.], and stretching speed γ [%/min] so that the following formulas (1) and (2) are satisfied when the thermoplastic resin film is stretched at the stretching ratio α [%], the temperature β [° C.], and the stretching speed γ [%/min], therefore, stretching unevenness can be prevented:

Z>X   (1)

(X×100/k)×0.2<(Y−X)×100/k   (2)

here X represents yield stress [MPa] in a stress-strain curve, Y represents stress [MPa] in the stress-strain curve when the film is further stretched from the yield stress by k [%] which is the amount of strain until the yield stress, and Z represents stress [MPa] in the stress-strain curve when the film is stretched to α [%].

Claims

1. A method for manufacturing a retardation film, comprising:

feeding a thermoplastic resin film; and

stretching the thermoplastic resin film while adjusting stretching ratio α

[%], temperature β

[°

C.], and stretching speed γ

[%/min] so that the following formulas (1) and (2) are satisfied when the thermoplastic resin film is stretched at the stretching ratio α

[%], the temperature β

[°

C.], and the stretching speed γ

[%/min];

Z>

X  

 

(1)

(X×

100/k)×

0.2<

(Y−

X)×

100/k  

 

(2)

wherein X represents yield stress [MPa] in a stress-strain curve, Y represents stress [MPa] in the stress-strain curve when the film is further stretched from the yield stress by k [%] which is an amount of strain until the yield stress, and Z represents stress [MPa] in the stress-strain curve when the film is stretched to α

[%].

2. The method for manufacturing a retardation film according to claim 1, wherein the thermoplastic resin is a cellulose acylate resin.

3. The method for manufacturing a retardation film according to claim 1, wherein the thermoplastic resin is a saturated norbornene-based resin.

4. A retardation film manufactured by the manufacturing method according to claim 1.

5. The retardation film according to claim 4, wherein in-plane retardation Re is 20 nm to 100 nm, thickness direction retardation Rth is 40 nm to 300 nm, and a ratio of Re and Rth, Rth/Re is 0.4 to 8.

6. The retardation film according to claim 4, wherein the thermoplastic resin is a cellulose acylate resin.

7. The retardation film according to claim 4, wherein the thermoplastic resin is a saturated norbornene-based resin.

8. The retardation film according to claim 4, wherein Re unevenness in a transverse direction is 10 nm or less, and Rth unevenness in the transverse direction is 20 nm or less.

9. The retardation film according to claim 8, wherein the thermoplastic resin is a cellulose acylate resin.

10. The retardation film according to claim 8, wherein the thermoplastic resin is a saturated norbornene-based resin.

11. A polarizing plate using the retardation film according to claim 4 as a substrate.