Claims
- 1. An optically isotropic film of an aromatic polyethersulfone which is free of halogen containing solvent, which
- (A) comprises an aromatic polyethersulfone,
- (B) has a transmittance to visible light at a wavelength of 550 nm in the range of from 86 to 91%,
- (C) has a haze value in the range of from 0.1 to 1%,
- (D) shows a refractive index difference (.DELTA.n) of 0.0010 or less, which is a difference between a refractive index (n.sub.s) in the slow axis direction in an in-plane area of the film and a refractive index (n.sub.f) in the fast axis direction in the in-plane area,
- (E) has a refractive index ratio (n.sub.z /n.sub.f) of 0.9997 to 1.0000, which is a ratio (n.sub.z /n.sub.f) of a refractive index (n.sub.z) in a perpendicular direction with regard to a film surface to the refractive index (n.sub.f),
- (F) has a thickness in the range of from 30 to 300 .mu.m, and
- (G) has a thickness nonuniformity in the range of from 0.1 to 1% based on an average film thickness.
- 2. A substrate for a liquid crystal display device which is free of halogen containing solvent, formed of the optically isotropic film as recited in claim 1.
- 3. An optically anisotropic, uniaxially oriented film of an aromatic polyethersulfone which is free of halogen containing solvent, which
- (A) comprises an aromatic polyethersulfone,
- (B) has a transmittance to visible light at a wavelength of 550 nm in the range of from 86 to 91%,
- (C) has a haze value in the range of from 0.1 to 1%,
- (D) shows a refractive index difference (.DELTA.n) in the range of from 0.0013 to 0.0230, which is a difference between a refractive index (n.sub.s) in the slow axis direction in an in-plane area of the film and a refractive index (n.sub.f) in the fast axis direction in the in-plane area,
- (F) has a thickness in the range of from 30 to 300 .mu.m, and
- (G) having a thickness nonuniformity in the range of from 0.1 to 1% based on an average film thickness.
- 4. A phase difference plate for a liquid crystal display device which is free of halogen containing solvent, formed of the optically anisotropic, uniaxially oriented film of claim 3.
- 5. The film of claim 3 which is free of halogen containing solvent, wherein the film has a phase difference (Re) in the range of from 400 to 700 nm at a wavelength of 590 nm and has a phase difference nonuniformity in the range of 0.01 to 2% of a phase difference.
- 6. A substrate for a liquid crystal display device which is free of halogen containing solvent and containing thereon the optically isotropic film of claim 1.
- 7. A phase difference plate which is free of halogen containing solvent for a liquid crystal display device comprising the optically anisotropic, uniaxially oriented film of claim 3.
Parent Case Info
This is a division of application Ser. No. 08/792,219 filed Jan. 31, 1997 now U.S. Pat. No. 5,759,449, which is a division of application Ser. No. 08/415,136, filed Mar. 30, 1995, now U.S. Pat. No. 5,645,766. Application Ser. No. 08/792,219 now U.S. Pat. No. 5,759,449 is incorporated herein in its entirety by reference thereto.
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Divisions (2)
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Number |
Date |
Country |
Parent |
792219 |
Jan 1997 |
|
Parent |
415136 |
Mar 1995 |
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