Polymer film and preparation method of polymer solution

• US 20050163923A1
• Filed: 01/26/2005
• Published: 07/28/2005
• Est. Priority Date: 01/26/2004
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Sasada, Yasuyuki
• Granted Patent: US 8,304,040 B2
• Time in Patent Office: Days
• US Class Current: 427/160
• CPC Class Codes: C08J 2301/10 Esters of organic acids
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 1/10 Esters of organic acids , i.e. acylates
• CPC Class Codes: C08L 1/12 Cellulose acetate
• CPC Class Codes: C09K 2323/035 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• 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 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis

Abstract

A polymer is swollen in a first tank. The swelling temperature is in the range of −10 to 50° C. The mixture is cooled in a first cooling vessel to the range of −100 to −10° C., and thereafter heated in a heating device to the range of 0 to 57° C. The polymer is cellulose acylate in which a degree of substitution of the acyl group for hydroxyl group is at least 2.87. A film obtained from the cellulose acylate has a negative value of ΔRe and a positive value of ΔRth, and |ΔRth| is at least 10 nm. ΔRe and ΔRth are respective difference of Re and Rth at the measurement thereof with use of wavelengths between 700 nm and 400 nm. The film is used adequately as a birefringence film, a protective film for a polarizing filter in a liquid crystal display.

Claims

1. A polymer film having an in-plane retardation Re(n) and a thickness retardation Rth(n) measured with use of a light of wavelength n (unit;

nm), comprising;

Δ

Re calculated by Re(700)−

Re(400); and

Δ

Rth calculated by Rth(700)−

Rth(400), a sing of said Δ

Rth being opposite to that of said Δ

Re.

2. A polymer film as defined in claim 1, wherein said Δ

Rth satisfies a formula of 10 nm≦

|Δ

Rth|≦

1000 nm.

3. A polymer film as defined in claim 1, wherein said Δ

Re is negative value.

4. A polymer film as defined in claim 1, wherein a polymer as a main content is cellulose acylate.

5. A polymer film as defined in claim 4, wherin said cellulose acylate has a degree of acylation at least 2.87.

6. A polymer film as defined in claim 1, wherein said polymer film is used as a retardation filter in a liquid crystal display including a liquid crystal cell sandwiched by a pair of orientation layers, and said retardation filter is oppositely disposed over said orientation layer to said liquid crystal cell.

7. A polymer film as defined in claim 1, wherein said polymer film is used as a protective film for a polarizing filter, and said protective film is adhered to at least one surface of a polarized film of said polarizing filter.

8. A preparation method of a polymer solution from a mixture containing a polymer and a solvent, comprising steps of:

regulating a temperature of said mixture in a range of −

10°

C. to 50°

C. such that said polymer may swell;

cooling said mixture after the swelling, such that the temperature of said mixture may be lower than at the swelling and in the range of −

100°

C. to −

10°

C.; and

heating said mixture after the cooling, such that said temperature of said mixture may be in the range of 0°

C. to 57°

C.

9. A preparation method as defined in claim 8, wherein the cooling of said mixture is performed under a increased pressure.

10. A preparation method as defined in claim 8, wherein main content of said solvent is chlorine type organic solvent.

11. A preparation method as defined in claim 8, wherein a polymer as a main content is cellulose acylate.

12. A preparation method as defined in claim 11, wherein said cellulose acylate has a degree of acylation at least 2.87.