STRETCHED FILM, PROCESS FOR PRODUCING THE SAME, AND LIQUID CRYSTAL DISPLAY DEVICE

• US 20100310793A1
• Filed: 11/12/2008
• Published: 12/09/2010
• Est. Priority Date: 11/27/2007
• Status: Active Grant

• Current Assignee: ZEON Corporation
• Original Assignee: ZEON Corporation
• Inventors: Takizawa, Tadashi
• Granted Patent: US 8,993,075 B2
• Time in Patent Office: Days
• US Class Current: 428/1.1
• CPC Class Codes: B29C 55/023 using multilayered plates or sheets
• CPC Class Codes: B29C 55/16 simultaneously
• CPC Class Codes: B29K 2025/00 Use of polymers of vinyl-aromatic compounds or derivatives thereof as moulding material
• CPC Class Codes: B29K 2033/08 Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate
• CPC Class Codes: B29K 2995/0032 Birefringent
• CPC Class Codes: B32B 2250/24 All layers being polymeric
• CPC Class Codes: B32B 2250/40 Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 23/20 comprising esters
• CPC Class Codes: B32B 2307/306 Resistant to heat
• CPC Class Codes: B32B 2307/40 having particular optical properties light or UV resistant B32B2307/71
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2307/50 having particular mechanical properties
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 2307/538 Roughness
• CPC Class Codes: B32B 2307/5825 Tear resistant
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/16 specially treated, e.g. irradiated
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/20 : using fillers, pigments, thixotroping agents
• CPC Class Codes: B32B 27/281 : comprising polyimides
• CPC Class Codes: B32B 27/285 : comprising polyethers
• CPC Class Codes: B32B 27/286 : comprising polysulphones; polysulfides
• CPC Class Codes: B32B 27/30 : comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/302 : comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/304 : comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• CPC Class Codes: B32B 27/306 : comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/308 : comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 : comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 : comprising polyesters
• CPC Class Codes: B32B 27/365 : comprising polycarbonates
• CPC Class Codes: C09K 2323/00 : Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• 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: Y10T 428/2495 : Thickness [relative or absolute]

Abstract

A stretched film comprised of a “B₁” layer comprised of a thermoplastic resin 1, an “A” layer comprised of a styrene-based resin, and a “B₂” layer comprised of a thermoplastic resin 2 stacked in that order and having a width of over 1000 mm, wherein a ratio of the “A” layer in the stretched film is 45 wt % or less, an average value of an orientation angle θ with respect to a width direction across at least 1000 mm of the width direction is 0°±1°, a variation in orientation angle θ is 0.5° or less, and a value of an Nz coefficient is −3.5 to −0.5 in range.

Claims

1. A stretched film comprised of a “

B₁”

layer comprised of a methacrylic resin 1, an “

A”

layer comprised of a styrene-based resin, and a “

B₂”

layer comprised of a methacrylic resin 2, stacked in that order, simultaneously biaxially stretched, and having a width of over 1000 mm, wherein

the ratio of the “

A”

layer in said stretched film is 45 wt % or less,

the average value of an orientation angle θ

with respect to a width direction across at least 1000 mm of the width direction is 0°

±

1°

,

the variation in the orientation angle θ

is 0.5°

or less, and

a value of an Nz coefficient is −

3.5 to −

0.5 in range.

2. The stretched film as set forth in claim 1, wherein said ratio of the “

A”

layer is 35 wt % or less.

3. The stretched film as set forth in claim 1 or 2, wherein the value of the variation of the Nz coefficient is 0.2 or less.

4. The stretched film as set forth in claim 1 or 2, wherein the average value of the in-plane direction retardation Re is 80 nm or less.

5. The stretched film as set forth in claim 1 or 2, wherein a variation of the in-plane direction retardation Re is 3 nm or less.

6. The stretched film as set forth in claim 1 or 2, wherein the in-plane direction retardation Re of at least one of said “

B₁”

layer and said “

B₂”

layer is 0 nm to 15 nm in range.

7. The stretched film as set forth in claim 1 or 2, wherein the ratio of the average thickness of said “

B₁”

layer and the average thickness of said “

A”

layer (“

B₁”

layer/“

A”

layer) is 2/1 to 1/1 and the ratio of the average thickness of said “

B₂”

layer and the average thickness of said “

A”

layer (“

A”

layer/“

B₂”

layer) is 1/1 to 1/2.

8. The stretched film as set forth in claim 1 or 2, wherein the haze is over 1% to not more than 5%.

9. An IPS type liquid crystal display device comprised of an optical device produced using the stretched film as set forth in claim 1 or 2.

10. A process for producing the stretched film as set forth in claim 1 or 2, comprising

a step of using melt coextrusion to obtain an unstretched laminate “

c”

comprised of a “

b₁”

layer comprised of a methacrylic resin 1, an “

a”

layer comprised of a styrene-based resin, and a “

b₂”

layer comprised of a methacrylic resin 2 stacked in that order and

a step of stretching said laminate by simultaneous biaxial stretching.

11. The process for producing the stretched film as set forth in claim 10 wherein the stretching temperature is less than a Vicat softening temperature+20°

C. of said styrene-based resin.

12. The process for producing the stretched film as set forth in claim 10 wherein the stretching ratio in the longitudinal direction is 1.0 to 1.5 times the stretching ratio in the width direction.