US5366682A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing phase retarder
Assignee: Sumitomo Chemical Co Ltd
•
Filing: 1992-12-09
•
Granted: 1994-11-22
•
Expires: 2012-12-09
Abstract
Abstract A process for producing a phase retarder film or sheet, which comprises subjecting a stretched thermoplastic resin film or sheet to thermal relaxation at a temperature not lower than the glass transition temperature of the thermoplastic resin to shrink the film or sheet in the stretching axis direction while suppressing the expansion of the film or sheet in a direction parallel to the film or sheet surface and perpendicular to the stretching axis.
Inventors
- 👤 Michitaka Morikawa
- 👤 Koji Higashi
- 👤 Tadashi Shindo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:55
CPC Classifications
B; B29; B29C; B29C71/00; B29C71/02; B29C61/00; B29C61/02; B29D; B29D7/00; B29D7/01; G; G02; G02B; G02B5/00; G02B5/30; G02B5/3083; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/13363; B29C55/00; B29K; B29K2069/00; B29K2995/00; B29K2995/0018; B29K2995/0026; B29K2995/0031; B29K2995/0032; B29L; B29L2011/00; Y; Y10; Y10S; Y10S264/00; Y10S264/71
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
162 words
A process for producing a phase retarder film or sheet, comprising the steps of subjecting a uniaxially stretched thermoplastic resin film or sheet to thermal relaxation at a temperature of at least the glass transition temperature of the thermoplastic resin to shrink the film or sheet in a stretching axis direction while suppressing expansion of the film or sheet in a direction parallel to the film or sheet surface and perpendicular to the stretching axis, wherein the thermal relaxation and expansion suppression are conducted until the retardation ratio of the film or sheet satisfies the following formula: 0.900<R.sub.40 /R.sub.0 <1.100 where R 40 is the retardation value measured with the film or sheet tilted 40° from horizontal around an axis corresponding to the slow axis if the thermoplastic resin has a positive intrinsic birefringence or the fast axis if the thermoplastic resin has a negative intrinsic birefringence and R 0 is the retardation value measured with the film or sheet arranged horizontally.
Claim 2
Dependent Claim
162 words
A process for producing a phase retarder film or sheet, comprising the steps of subjecting a uniaxially stretched thermoplastic resin film or sheet to thermal relaxation at a temperature of at least the glass transition temperature of the thermoplastic resin to shrink the film or sheet in a stretching axis direction while suppressing expansion of the film or sheet in a direction parallel to the film or sheet surface and perpendicular to the stretching axis, wherein the thermal relaxation and expansion suppression are conducted until the retardation ratio of the film or sheet satisfies the following formula: 0.900<R.sub.40 /R.sub.0 <1.100 where R 40 is the retardation value measured with the film or sheet tilted 40° from horizontal around an axis corresponding to the slow axis if the thermoplastic resin has a positive intrinsic birefringence or the fast axis if the thermoplastic resin has a negative intrinsic birefringence and R 0 is the retardation value measured with the film or sheet arranged horizontally.
Claim 3
Dependent Claim
40 words
A process according to claim 1, wherein the thermal relaxation is conducted while maintaining a constant length of the film or sheet in a direction parallel to the surface of the film or sheet and perpendicular to the stretching axis.
Claim 4
Dependent Claim
35 words
A process according to claim 1, wherein the thermal relaxation is conducted while applying pressure to the surface of the film or sheet in a direction perpendicular to the surface of the film or sheet.
Claim 5
Dependent Claim
60 words
A process according to claim 1, wherein the thermal relaxation is conducted while maintaining a constant length of the film or sheet in a direction parallel to the surface of the film or sheet and perpendicular to the stretching axis and applying pressure to the film or sheet in a direction perpendicular to the surface of the film or sheet.
Claim 6
Dependent Claim
103 words
A process according to claim 2, wherein the length of the film or sheet in a direction parallel to the surface of the film or sheet and perpendicular to the stretching axis is maintained constant by arranging the film or sheet in a frame wherein the film or sheet is not allowed to expand in a direction parallel to the surface of the film or sheet and perpendicular to the stretching axis of the film or sheet, thereby suppressing expansion of the film or sheet in the direction parallel to the surface of the film or sheet and perpendicular to the stretching axis.
Claim 7
Dependent Claim
104 words
A process according to claim 4, wherein the length of the film or sheet in a direction parallel to the surface of the film or sheet and perpendicular to the stretching axis is maintained constant by arranging the film or sheet in a frame wherein the film or sheet is not allowed to expand in a direction parallel to the surface of the film or sheet surface and perpendicular to the stretching axis of the film or sheet, thereby suppressing expansion of the film or sheet in the direction parallel to the surface of the film or sheet and perpendicular to the stretching axis.
Claim 8
Dependent Claim
19 words
A process according to claim 3, wherein the pressure is between 0.1 g/cm 2 to 10 Kg/cm 2 .
Claim 9
Dependent Claim
19 words
A process according to claim 4, wherein the pressure is between 0.1 g/cm 2 to 10 Kg/cm 2 .
Claim 10
Dependent Claim
38 words
A process according to claim 1, wherein the thermal relaxation is carried out at a temperature between the glass transition temperature of the thermoplastic resin and 50° C. higher than the glass transition temperature of the thermoplastic resin.
Claim 11
Dependent Claim
15 words
A process according to claim 1, wherein the thermoplastic resin has a positive intrinsic birefringence.
Claim 12
Dependent Claim
28 words
A process according to claim 10, wherein the thermoplastic resin is selected from the group consisting of a polycarbonate, a polysulfone, a polyacrylate, a polyethersulfone and cellulose diacetate.
Claim 13
Dependent Claim
13 words
A process according to claim 11, wherein the thermoplastic resin is a polycarbonate.
Claim 14
Dependent Claim
15 words
A process according to claim 1, wherein the thermoplastic resin has a negative intrinsic birefringence.
Claim 15
Dependent Claim
29 words
A process according to claim 13, wherein the thermoplastic resin is selected from the group consisting of a polystyrene, an α-methylpolystyrene, a polyvinylpyridine, a polyvinylnaphthalene and a polymethyl methacrylate.
References Cited (Backward Citations)
US3445561A
Cited
US3577510A
Cited
US4160799A
Cited
JPS61167531A
Cited
US5061042A
Cited
JPH0289006A
Cited
JPH02191904A
Cited
JPH02160204A
Cited
US5244713A
Cited
JPH02285303A
Cited
US5235450A
Cited
EP0482620A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-11-21 | 1998-05-23 | 1998-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-21 | 2002-05-23 | 2002-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-21 | 2006-05-23 | 2006-11-22 | $7700.00 | Window Closed / Lapsed |