METHOD OF MANUFACTURING CELLULOSE FILM, MANUFACTURING APPARATUS, OPTICAL FILM, POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY

• US 20070148371A1
• Filed: 12/21/2006
• Published: 06/28/2007
• Est. Priority Date: 12/26/2005
• Status: Active Grant

• Current Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Original Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Inventors: KAZAMA, Kenichi
• Granted Patent: US 8,349,228 B2
• Time in Patent Office: Days
• US Class Current: 428/1.310
• CPC Class Codes: B29C 43/222 characterised by the shape of the surface
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/313 by positioning the die lips
• CPC Class Codes: B29C 48/91 Heating, e.g. for cross linking
• CPC Class Codes: B29C 48/914 cooling drums
• CPC Class Codes: B29C 48/9155 Pressure rollers
• CPC Class Codes: B29C 55/08 transverse to the direction of feed
• 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 2995/0032 Birefringent
• CPC Class Codes: C08J 2301/10 Esters of organic acids
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• 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

Abstract

An optical film characterized by a high degree of flatness that can be used as a phase difference film of a liquid crystal display, and a method for manufacturing this optical film according to melt-casting film forming method. A melt including a cellulose resin is extruded onto a rotary support member 5 (cooling roll) from a flow casting die 4. A rotary pinch member 6 (touch roll) is energized to the rotary support member 5, and a nip is formed between them. When the melt is sandwiched and pressed by the nip, a die line and irregularity in thickness are removed. The linear pressure of the rotary pinch member 6 and the temperature of the melt immediately before the melt is sandwiched and pressed by the nip are set within a predetermined range, whereby effective correction of the film flatness is achieved.

Claims

1. A cellulose film manufacturing apparatus, comprising:

a flow casting die for extruding melted material including cellulose resin in a sheet-like shape;

a rotary support member for supporting, while rotating, the sheet-like melted material extruded from the flow cast die, in order of extrusion, on a surface thereof; and

a rotary pinch member for forming a film of the melted material by pinching by a nip portion which is formed between the rotary support member and the rotary pinch member energized thereto, the rotary pinch member including a roller covered with a flexible metal sleeve whose thickness is not less than 0.1 mm and not more than 1.5 mm or a roller provided with a metal outer cylinder whose thickness is not less than 0.008 times and not more than 0.05 times of a radius of the roller,

wherein a force F, with which the rotary pinch member is energized to the rotary support member, divided by a width W of the film at the nip portion is not less than 1 kN/m and not more than 15 kN/m, and a temperature T of the melded material just before being pinched by the nip portion and a glass transition temperature Tg of the cellulose resin satisfy the following relationship;

Tg<

T<

Tg+110°

C.

2. The cellulose film manufacturing apparatus of claim 1, wherein an average thickness d1 of an edge area within 30 mm from an edge of the sheet-like melted material with respect to a width direction perpendicular to a rotating direction of the rotary support member and an average thickness d2 of an inner part than the edge area satisfy the following relationship:

d1<

d2

3. The cellulose film manufacturing apparatus of claim 1, wherein an interior portion of the metal sleeve is filled with fluid.

4. The cellulose film manufacturing apparatus of claim 1, wherein the roller covered with the metal sleeve includes an elastic roll, and the metal sleeve is pressed against the rotary support member by the elastic roll.

5. The cellulose film manufacturing apparatus of claim 4, wherein the elastic roll is constituted with an inner metal cylinder rotatably supported and provided with rubber on a surface thereof.

6. The cellulose film manufacturing apparatus of claim 1, wherein the metal outer cylinder includes a space therein and is mounted on a pair of flanges which are disposed on an axis of rotation.

7. The cellulose film manufacturing apparatus of claim 6, wherein a passage of fluid is provided in the space.

8. The cellulose film manufacturing apparatus of claim 1, wherein the force F, with which the rotary pinch member is energized to the rotary support member, divided by the width W of the film at the nip portion is not less than 5 kN/m and not more than 10 kN/m.

9. An optical film manufactured by a cellulose film manufacturing apparatus, the manufacturing apparatus comprising:

a flow casting die for extruding melted material including cellulose resin in a sheet-like shape;

a rotary support member for supporting, while rotating, the sheet-like melted material extruded from the flow cast die, in order of extrusion, on a surface thereof; and

a rotary pinch member for forming a film of the melted material by pinching by a nip portion which is formed between the rotary support member and the rotary pinch member energized thereto, the rotary pinch member including a roller covered with a flexible metal sleeve whose thickness is not less than 0.1 mm and not more than 1.5 mm or a roller provided with a metal outer cylinder whose thickness is not less than 0.008 times and not more than 0.05 times of a radius of the roller,

wherein a force F, with which the rotary pinch member is energized to the rotary support member, divided by a width W of the film at the nip portion is not less than 1 kN/m and not more than 15 kN/m, and a temperature T of the melded material just before being pinched by the nip portion and a glass transition temperature Tg of the cellulose resin satisfy the following relationship;

Tg<

T<

Tg+110°

C.

10. A polarizing plate which comprises, as a protection film, an optical film manufactured by a cellulose film manufacturing apparatus, the manufacturing apparatus including:

a flow casting die for extruding melted material including cellulose resin in a sheet-like shape;

a rotary support member for supporting, while rotating, the sheet-like melted material extruded from the flow cast die, in order of extrusion, on a surface thereof; and

a rotary pinch member for forming a film of the melted material by pinching by a nip portion which is formed between the rotary support member and the rotary pinch member energized thereto, the rotary pinch member including a roller covered with a flexible metal sleeve whose thickness is not less than 0.1 mm and not more than 1.5 mm or a roller provided with a metal outer cylinder whose thickness is not less than 0.008 times and not more than 0.05 times of a radius of the roller,

wherein a force F, with which the rotary pinch member is energized to the rotary support member, divided by a width W of the film at the nip portion is not less than 1 kN/m and not more than 15 kN/m, and a temperature T of the melded material just before being pinched by the nip portion and a glass transition temperature Tg of the cellulose resin satisfy the following relationship;

Tg<

T<

Tg+110°

C.

11. An liquid crystal display which comprises a polarizing plate including, as a protection film, an optical film manufactured by a cellulose film manufacturing apparatus, the manufacturing apparatus having:

a flow casting die for extruding melted material including cellulose resin in a sheet-like shape;

a rotary support member for supporting, while rotating, the sheet-like melted material extruded from the flow cast die, in order of extrusion, on a surface thereof; and

a rotary pinch member for forming a film of the melted material by pinching by a nip portion which is formed between the rotary support member and the rotary pinch member energized thereto, the rotary pinch member including a roller covered with a flexible metal sleeve whose thickness is not less than 0.1 mm and not more than 1.5 mm or a roller provided with a metal outer cylinder whose thickness is not less than 0.008 times and not more than 0.05 times of a radius of the roller,

wherein a force F, with which the rotary pinch member is energized to the rotary support member, divided by a width W of the film at the nip portion is not less than 1 kN/m and not more than 15 kN/m, and a temperature T of the melded material just before being pinched by the nip portion and a glass transition temperature Tg of the cellulose resin satisfy the following relationship;

Tg<

T<

Tg+110°

C.

12. A method for manufacturing a cellulose film, the method comprising the steps of:

extruding melted material including cellulose resin, in a sheet-like shape, out of the flow casting die;

supporting the melted material extruded from the flow casting die, in order of extrusion, on a surface of a rotary pinch member while rotating the rotary pinch member; and

forming a film out of the melted material by pinching the melted material at a nip portion which is formed between the rotary support member and the rotary pinch member energized thereto,

wherein a force F, with which the rotary pinch member is energized to the rotary support member, divided by a width W of the film at the nip portion is not less than 1 kN/m and not more than 15 kN/m, the rotary pinch member includes a roller covered with a flexible metal sleeve whose thickness is not less than 0.1 mm and not more than 1.5 mm or a roller provided with a metal outer cylinder whose thickness is not less than 0.008 times and not more than 0.05 times of a radius of the roller, the metal sleeve is energized to the rotary support member, and the rotary pinch member pinches the melted material when a temperature T of the melded material just before being pinched by the nip portion and a glass transition temperature Tg of the cellulose resin satisfy the following relationship;

Tg<

T<

Tg+110°

C.