Cellulose ester film, optical film, polarizing plate,...

Details Cellulose ester film, optical film, polarizing plate,... Cellulose ester film, optical film, polarizing plate,...

2001-05-08

2004-03-30

Seidleck, James J. (Department: 1711)

Compositions: coating or plastic

Coating or plastic compositions

Carbohydrate or derivative containing

C428S050000, C536S063000, C536S064000, C536S065000, C536S067000, C536S068000, C536S069000

Reexamination Certificate

active

06712896

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to cellulose ester film, an optical film for optical use, a polarizing plate, an optical compensation film and a liquid crystal display, and particularly to an optical film such as a protective film of a polarizing plate, a phase difference film, or a viewing angle increasing film used in a liquid crystal display, various functional films such as an anti-reflective film used in a plasma display or various functional films used in an organic EL display.
BACKGROUND OF THE INVENTION
Recently, a compact note type personal computer displaying a highly precise image has been developed. Synchronizing with the development, a protective film of a polarizing plate, which is thinner and has a higher performance, has been required. Cellulose ester is widely used as material of a protective film of a polarizing plate, in view of its transparency and refractive index. However, a simple thinning of the film produces various problems.
A cellulose ester film used in a protective film of a polarizing plate contains an ultraviolet absorber, in order to protect a polarizing element or a liquid crystal from ultraviolet light. Accordingly, a simple thinning of the film cannot sufficiently shield ultraviolet light, and therefore, the ultraviolet absorber amount contained in the film need be increased.
There is a proposal regarding an ultraviolet absorber in Japanese Patent O.P.I. Publication Nos. 6-130226 and 7-11056.
It has been found that the increased amount in the film of the ultraviolet absorber proposed in these patents produces problems in that the ultraviolet absorber is adhered to peeling rollers or transporting rollers during manufacture of the film, and produces troubles or lowers production efficiency.
There is proposed, in Japanese Patent O.P.I. Publication No. 8-148430, a protective film of a polarizing plate contains an ultraviolet absorbent polymer.
However, the ultraviolet absorbent polymer proposed in this patent has poor compatibility with cellulose ester. The increased amount of the polymer provides a high haze, and the polymer is not satisfactory in its application to a liquid crystal display requiring high precision
An optical compensation film is a film having optically anisotropy capable of being used in a liquid crystal display as an alternative of CRT.
A liquid crystal display has problems in viewing angle that displaying images quality lower when viewing obliquely, since it employs a liquid crystalline material having anisotropy, and its improvement has been desired.
Anisotropic materials, which are obtained by fixing orientation of a liquid crystalline compound, have been mainly used as an optical compensation film. They are ordinarily manufactured by coating a liquid crystalline compound-containing solution on a cellulose ester film. An ultraviolet absorber contained in the cellulose ester film has problems in that it bleeds out and contaminates the liquid crystalline compound, resulting in disorder of orientation of the liquid crystalline compound or haze of the film.
SUMMARY OF THE INVENTION
An object of the invention is to provide a cellulose ester film with few coating defects, excellent productivity, and excellent transparency, and to provide an optical film, a polarizing plate, an optical compensation film and a liquid crystal display each employing the film.
Another object of the invention is to provide an optical film having an excellent spectral absorption property, reduced bleed out, and an excellent weather-proof.
DETAILED DESCRIPTION OF THE INVENTION
The above problems in the invention can be solved by the following constitutions:
1. A cellulose ester film comprising (a) an ultraviolet absorbent polymer having at least one of repeating units represented by the following formulae (1) and (2) and repeating units having ultraviolet absorbent structures represented by the following formulae (3), (4) and (5), (b) an ultraviolet absorbent polymer which is a copolymer of a repeating unit represented by the following formula (6), (7) or (19) with a monomer unit derived from another ethylenically unsaturated monomer, (c) an ultraviolet absorbent polymer which is a copolymer of a monomer represented by the following formula (8) with a monomer represented by the following formula (9), or (d) modified cellulose in which an ultraviolet absorbent structure bonds directly or through a spacer to a hydroxy group of cellulose or its derivative:
wherein J
1
represents —O—, —NR
1
—, —S—, —SO—, —SO
2
—, —POO—, —CO—, —COO—, —NR
2
CO—, —NR
3
COO—, —NR
4
CONR
5
—, —OCO—, —OCONR
6
—, —CONR
7
—, —NR
8
SO—, —NR
9
SO
2
—, —SONR
10
—, or —SO
2
NR
11
—, in which R
1
through R
11
independently represent a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; and Sp
1
represents a divalent linkage which may have a halogen atom or a substituent, provided that an ultraviolet absorbent structure bonds directly or through a spacer to Sp
1
or forms a part of the polymer main chain,
wherein J
2
and J
3
represent the same group as J
1
denoted in formula (1) above, and may be the same or different; Sp
2
and Sp
3
independently represent a divalent linkage which may have a halogen atom or a substituent, and may be the same or different, provided that an ultraviolet absorbent structure bonds directly or through a spacer to at least one of Sp
2
and Sp
3
or forms a part of the polymer main chain in at least one of Sp
2
and Sp
3
,
wherein R
12
through R
25
independently represent a hydrogen atom, a halogen atom or a substituent, provided that the two adjacent groups of R
12
through R
25
may combine with each other to form a ring, and provided that the ultraviolet absorbent structure of formula (3) bonds directly or through a spacer to the polymer main chain or forms a part of the polymer main chain,
wherein R
26
and R
27
independently represent an alkyl group having a carbon atom number of 1 to 10; R
28
, R
29
and R
30
independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group or a substituted or unsubstituted amino group; X and Y independently represent an electron withdrawing group, provided that R
26
through R
30
, X and Y may have a halogen atom or a substituent or may combine with another to form a 5- or 6-member ring, and provided that the ultraviolet absorbent structure of formula (4) bonds directly or through a spacer to the polymer main chain or forms a part of the polymer main chain,
wherein R
66
through R
71
independently represent a hydrogen atom, a halogen atom or a substituent, provided that the two adjacent groups of R
66
through R
71
may combine with each other to form a ring; X and Y independently represent an electron withdrawing group, provided that X and Y may have a halogen atom or a substituent but do not combine with each other to form a ring; and provided that the ultraviolet absorbent structure of formula (5) bonds directly or through a spacer to the polymer main chain or forms a part of the polymer main chain,
wherein R
31
and R
32
independently represent a halogen atom or a substituent; l represents 0, 1, 2, or 3, provided that when l is 2 or 3, plural R
31
s may be the same or different; m represents 0, 1, 2, 3, or 4, provided that when m is 2, 3 or 4, plural R
32
s may be the same or different; J
4
represents a group selected from *—O—, *—NR
1
—, *—S—, *—SO—, *—SO
2
—, *—POO—, *—CO—, *—COO—, *—NR
2
CO—, *—NR
3
COO—, *—NR
4
CONR
5
—, *—OCO—, *—OCONR
6
—, *—CONR
7
—, *—NR
8
SO—, *—NR
9
SO
2
—, *—SONR
10
—, *—SO
2
NR
11
— or *—OCOR
12
—, in which symbol “*” represents that the group bonds to the ultraviolet absorbent structure at the position “*” (on the side of J
4
opposite Sp
4
) and R
1
through R
12
independently represent the same as R
1
through R
11
denoted in formula (1) above; and Sp
4
represents a divalent linkage which may have a halogen atom or a substituent,
wherein R
33
and R
34
independently represent a halogen atom or a

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