JPH10218938A - Element with alignment layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical compensating sheet which hardly undergoes reticulation in storage at high temp. and humidity and is excellent in wet heat resistance by cross-linking a polyvinyl alcohol polymer with a dialdehyde compd. in the presence of an acid and forming an alignment layer made of the cross- linked polyvinyl alcohol polymer and a liq. crystalline compd. layer on a transparent substrate. SOLUTION: The polyvinyl alcohol polymer is represented by the formula (wherein L<11> is an ether, urethane, acetal, or ester bond; R<11> is alkylene; L<12> is a group linking R<11> to L<11> ; Q<11> is vinyl, oxiranyl, or aziridinyl; x1 is 10-99.9mol%; y<1> is 0.01-80mol%; z1 is 0-70mol%; x1 +y1 +z1 =100; and k and h are each 0 or 1). The substrate is pref. one having a light transmission of 80% or higher. The liq. crystaline compd. used is a disklike one. The dialdehyde compd. is, e.g. glyoxal. The acid is, e.g. sulfuric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an element having an alignment film which can be used for an optical compensatory sheet and an optical element such as a liquid crystal cell of a liquid crystal display element.

[0002]

2. Description of the Related Art A CRT (cathode ray tube) has been mainly used as a display device of OA equipment such as a desktop personal computer and a word processor. 2. Description of the Related Art Recently, liquid crystal display devices (hereinafter, referred to as LCDs) are widely used instead of CRTs because of their thinness, light weight, and low power consumption. An LCD generally includes a liquid crystal cell and a pair of polarizing plates provided on both sides thereof. Most of such LCDs use a twisted nematic liquid crystal.

[0003] LCD display systems can be broadly divided into birefringence mode and optical rotation mode. 2. Description of the Related Art A super twisted nematic liquid crystal display device (hereinafter, referred to as an STN-LCD) using a birefringent mode uses a super twisted nematic liquid crystal having a twist angle exceeding 90 degrees and steep electro-optical characteristics. . Therefore, such an STN-LCD can display a large capacity by time-division driving. However, STN-LC
D has a problem that the response speed is slow (several hundred milliseconds) and gray scale display is difficult. Therefore, the display characteristics of the liquid crystal display devices (eg, TFT-LCD and MIM-LCD) using the active elements are difficult. Inferior compared. TFT-LCD and MIM-
In LCDs, twisted nematic liquid crystals having a 90 degree twist angle and positive birefringence are used to display images. In the display mode of the TN-LCD,
High-speed response (several tens of milliseconds) and high contrast are obtained. Thus, the optical rotation mode has many advantages over the birefringence mode and other modes. However, TN
-LCDs have different display colors and display contrast depending on the viewing angle of the liquid crystal display device (viewing angle characteristics).
The display characteristics have not reached the level of the CRT.

To improve the viewing angle characteristics (ie, to increase the viewing angle), Japanese Patent Application Laid-Open No. Hei 4-1992 proposes providing a retardation plate (optical compensation sheet) between a pair of polarizing plates and a liquid crystal cell.
229828 and JP-A-4-258923. The retardation plate proposed in the above-mentioned publication does not exert any optical action from directly in front of the liquid crystal cell because the retardation in the vertical direction is almost 0, but the retardation appears when tilted. This compensates for the phase difference generated in the liquid crystal cell. This phase difference brings about unfavorable viewing angle characteristics such as coloring and disappearance of the displayed image.
As such an optical compensation sheet, a sheet having negative birefringence so as to compensate for positive birefringence of a nematic liquid crystal and having an inclined optical axis is effective.

JP-A-8-5837 discloses a transparent support,
There is disclosed an optical compensation sheet comprising an alignment film made of rubbed polyvinyl alcohol provided thereon and an optically anisotropic layer of a discotic (discotic) liquid crystal compound formed on the present alignment film. The optical compensation sheet of the present invention can provide a wide viewing angle particularly by using a discotic liquid crystalline compound. However, this optical compensatory sheet causes a serious problem in practical use when it is used or stored for a long time, reticulation (net-like wrinkles) occurs, and the optically anisotropic layer is peeled off from the alignment film. Had.

EP 726,486 A2 discloses an optical compensatory sheet in which a group capable of reacting with a liquid crystal compound is introduced into polyvinyl alcohol, and an alignment layer and an optically anisotropic layer are chemically bonded. ing. By chemically bonding the alignment film layer and the optically anisotropic layer, the above-mentioned problem that the optically anisotropic layer was peeled off from the alignment film was solved. On the other hand, when used or stored for a long time, the above-mentioned problem that reticulation occurs may be improved to a certain degree, but it is not enough, especially for storage under high temperature and high humidity conditions. And the effect was not enough. In addition, German patent No. 1
No. 9,614,210A1 discloses an optical compensation sheet in which polyvinyl alcohol as a polymer of an alignment film is crosslinked and hardened. This optical compensatory sheet has been used for a long time, or the above-mentioned problem that reticulation occurs when stored, although a certain degree of improvement is still recognized, but it is not sufficient, especially under high temperature and high humidity conditions. Was not sufficiently effective for the preservation of

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an element which is easy to manufacture, provides an enlarged viewing angle, and has excellent durability even under high temperature and high humidity conditions. Another object of the present invention is to provide an element having an alignment film capable of easily aligning a liquid crystal compound, particularly a discotic liquid crystal compound, and stably aligning it for a long period of time.

[0008]

Means for solving the problems are as follows: 1) A transparent support, an alignment film made of a polyvinyl alcohol-based polymer, and a layer made of a liquid crystal compound are provided in this order. ,
An element characterized in that the polymer is crosslinked and hardened with a bifunctional aldehyde compound in the presence of an acid. 2) The element according to 1) above, wherein the liquid crystalline compound is a discotic liquid crystalline compound. 3) The element according to 1) above, wherein the polyvinyl alcohol-based polymer is a polymer represented by the following general formula (I). General formula (I)

[0009]

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(Where L ¹¹ represents an ether bond, a urethane bond, an acetal bond or an ester bond;
¹¹ represents an alkylene group, L ¹² represents a linking group connecting R ¹¹ and Q ¹¹ , Q ¹¹ represents vinyl, oxiranyl or aziridinyl, and x ₁ + y ₁ + z ₁ = 10
Under the condition of 0, x ₁ is 10 to 99.9 mol%, y ₁ is 0.01 to 80 mol%, and z ₁ is 0 to 70 mol%, and k and h are each 0 or 1 It is. 4) In the above item 1), the polyvinyl alcohol-based polymer may have at least one group represented by the following general formula (II).
An element which is a polyvinyl alcohol derivative in which two hydroxyl groups have been substituted. General formula (II)

[0011]

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(Provided that R ²¹ represents an alkyl group or an alkyl group substituted with alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy, and W ²¹ represents Alkyl group, alkyl,
Alkyl, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy substituted alkyl group, alkoxy group, or alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyl Represents an alkoxy group substituted by oxy or crotonoyloxy, q is 0 or 1, and n is an integer of 0-4. 5) The element according to 1) above, wherein the polyvinyl alcohol-based polymer is a polymer represented by the following general formula (III). General formula (III)

[0013]

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[0014] (wherein, L ³¹ represents an ether bond, a urethane bond, an acetal bond or an ester bond, A ³¹
Represents an arylene group; R ³¹ represents an alkylene group; L ³² represents a linking group connecting R ³¹ and Q ³¹ ;
³¹ represents vinyl, oxiranyl or aziridinyl, and under the condition of x ₂ + y ₂ + z ₂ = 100, x ₂ is 10
99.9 mol%, y ₂ is 0.01 to 80 mol%, and z ₂ are 0 to 70 mol%, k _1, h ₁ and f
Is 0 or 1, respectively. 6) The element according to 1) above, wherein the amount of the acid is from 100 μmol to 10 mmol per 1 g of the polyvinyl alcohol-based polymer. Achieved by

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a polyvinyl alcohol polymer which can be preferably used in the present invention will be described in detail. The polyvinyl alcohol-based polymer of the present invention is preferably 1) unmodified polyvinyl alcohol 2) modified polyvinyl alcohol 3) polyvinyl alcohol derivative represented by the above formula (I) 4) at least a group represented by the above formula (II) Polyvinyl alcohol derivative in which one hydroxyl group is substituted 5) The polyvinyl alcohol derivative represented by the general formula (III).

The unmodified polyvinyl alcohol has, for example, a saponification degree of 70 to 100%, generally has a saponification degree of 80 to 100%, and more preferably has a saponification degree of 8 to 100%.
5 to 95%. The degree of polymerization is 100-3
A range of 000 is preferred. As the modified polyvinyl alcohol, those modified by copolymerization (for example, COONa, Si (OH) ₃ , N (CH ₃ ) ₃ .C
1, C ₉ H ₁₉ COO, SO ₃ , Na, C ₁₂ H _{25 and the} like are introduced), and those modified by chain transfer (for example, COONa, SH, C ₁₂ H _{25 and the} like are introduced as modifying groups) ), Those modified by block polymerization (as modifying groups, for example, COOH, CONH ₂ , COOR, COR
₆ H ₅ or the like is introduced). The degree of polymerization is 100-3
A range of 000 is preferred. Of these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferred, and unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% is more preferred.

The polyvinyl alcohol-based polymer of the present invention includes, in particular: 1) a polyvinyl alcohol derivative represented by the above formula (I) 2) at least one hydroxyl group is substituted by a group represented by the above formula (II) Polyvinyl alcohol derivative 3) Polyvinyl alcohol derivative represented by general formula (III) is preferable.

In the general formula (I), R ¹¹ is generally an alkylene group having 1 to 24 carbon atoms and at least one non-adjacent CH ₂ group represents —O—, CO—, —NH—, —N
R ⁷ - (R ⁷ represents an alkyl or aryl having 6 to 15 carbon atoms having 1 to 4 carbon atoms), - S -, - SO
₂ -or an alkylene group having 3 to 24 carbon atoms replaced by an arylene having 6 to 15 carbon atoms, or alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, halogen, alkylcarbonyl, arylcarbonyl, alkylsulfonyl, arylsulfonyl , Hydroxyl, mercapto, amino, alkylcarbonyloxy, arylcarbonyloxy, alkylsulfonyloxy, arylsulfonyloxy, alkylcarbonylthio, arylcarbonylthio, alkylsulfonylthio, arylsulfonylthio, alkylcarbonylamino, arylcarbonylamino, alkylsulfonylamino , Arylsulfonylamino, carboxy or any of the above alkylene groups substituted with sulfo.

R¹¹Is -R^Two-, -R^Three-(OR^Four)_t
-OR^Five-, -R^Three-CO-R⁶-, -R^Three-NH-R
⁶-, -R^Three-NR⁷-R⁶-, -R^Three-SR⁶−,
-R ^Three-SO_Two-R⁶-Or -R^Three-A^Two-R⁶-(But
Then R^Two, R^Three, R^Four, R^FiveAnd R⁶Is carbon
R 1 represents an alkylene having 1 to 24 atoms;⁷Is a carbon source
Alkyl having 1 to 12 children or ant having 6 to 15 carbon atoms
And A^TwoIs arylene having 6 to 24 carbon atoms
And t represents an integer from 0 to 4)
Is preferred. Further, R¹¹Is -R^Two-Or-
R^Three− (O-CH_TwoCH_Two)_t-(However, R^TwoAnd R^ThreeIs it
Alkylene having 1 to 12 carbon atoms and t is 0 to 2
Is an integer. ), Especially R
¹¹Is preferably an alkylene having 1 to 12 carbon atoms.

The alkylene group may have a substituent. Examples thereof include alkyl having 1 to 24 carbon atoms, aryl having 6 to 24 carbon atoms, and 1 to 2 carbon atoms.
4 alkoxy, 6 to 24 carbon atom aryloxy, 1 to 24 carbon atom alkylthio, 6 carbon atoms
To 24 arylthio, halogen (F, Cl, Br),
Alkylcarbonyl having 2 to 24 carbon atoms, arylcarbonyl having 7 to 24 carbon atoms, alkylsulfonyl having 1 to 24 carbon atoms, arylsulfonyl having 6 to 24 carbon atoms, hydroxyl, mercapto, amino, having 2 carbon atoms Alkylcarbonyloxy having 24 to 24 carbon atoms, arylcarbonyloxy having 7 to 24 carbon atoms, and having 1 carbon atom
24 alkylsulfonyloxys having 6 to 24 carbon atoms
Arylsulfonyloxy, alkylcarbonylthio having 2 to 24 carbon atoms, arylcarbonylthio having 7 to 24 carbon atoms, alkylsulfonylthio having 1 to 24 carbon atoms, arylsulfonylthio having 6 to 24 carbon atoms, carbon Alkylcarbonylamino having 2 to 24 atoms,
Examples thereof include arylcarbonylamino having 7 to 24 carbon atoms, alkylsulfonylamino having 1 to 24 carbon atoms, arylsulfonylamino having 6 to 24 carbon atoms, carboxy and sulfo.

Preferred examples of the substituent of the alkylene group include alkyl having 1 to 24 carbon atoms (particularly, alkyl having 1 to 24 carbon atoms).
To 12), aryl having 6 to 24 carbon atoms (particularly 6 to 14 carbon atoms), and alkoxyalkyl having 2 to 24 carbon atoms (particularly 2 to 12 carbon atoms). Examples of alkyl include methyl, ethyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n
-Nonyl, n-decyl, n-undecyl, n-dodecyl, i-propyl, i-butyl, sec-butyl, t-
Amyl and 2-ethylhexyl can be mentioned.
Examples of alkyl substituted with 1-4 alkoxy include 2-methoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- [2- (2-methoxyethoxy) ethoxy] ethyl, 2-n- Butoxyethyl, 2-ethoxyethyl, 2- (2-ethoxyethoxy) ethyl, 3-methoxypropyl, 3-ethoxypropyl, 3-n-propyloxypropyl and 2-methylbutyloxymethyl. Examples of aryl include phenyl, 2-tolyl, 3-tolyl, 4-tolyl, 2-anisyl, 3-anisyl, 4-anisyl, 2-biphenyl,
-Biphenyl, 4-biphenyl, 2-chlorophenyl,
Examples include 3-chlorophenyl, 4-chlorophenyl, 1-naphthyl and 2-naphthyl. Examples of the heterocyclic group include pyridyl, pyrimidyl, thiazolyl, and oxazolyl.

L ¹² represents —O—, —S—, —CO—, —O
-CO-, -CO-O-, -O-CO-O-, -CO-
O-CO-, -NRCO-, -CONR-, -NR-,
-NRCONR-, -NRCO-O- or -OCON
It is preferable to represent R- (where R represents a hydrogen atom or a lower alkyl group). − (L ¹² ) _n −Q ¹² is
Vinyl, vinyloxy, acryloyl, methacryloyl, crotonoyl, acryloyloxy, methacryloyloxy, crotonoyloxy, vinylphenoxy, vinylbenzoyloxy, styryl, 1,2-epoxyethyl, 1,2-epoxypropyl, 2,3-epoxypropyl, It is preferably 1,2-iminoethyl, 1,2-iminopropyl or 2,3-iminopropyl.
Further, vinyl, vinyloxy, acryloyl, methacryloyl, acryloyloxy, methacryloyloxy,
Crotonoyloxy, vinylbenzoyloxy, 1,2
-Epoxyethyl, 1,2-epoxypropyl, 2,3
-Epoxypropyl, 1,2-iminoethyl, 1,2-
Iminopropyl or 2,3-iminopropyl is preferred. Particularly, acryloyl, methacryloyl, acryloyloxy and methacryloyloxy are preferred.

Under the condition of x ₁ + y ₁ + z ₁ = 100, x
₁ is preferably 50 to 99.9 mol%, and y ₁ is 0.01
To 50 mol% (more preferably 0.01 to 20 mol%)
It is preferred, especially 0.01 to 10 mol%, and most preferably 0.01 to 5 mol%) and z ₁ is preferably 0.01 to 50 mol%.

When L ¹¹ in the general formula (I) is an acetal bond, the polyvinyl alcohol derivative of the general formula (I) can be represented by the following general formula (Ia).

[0025]

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(However, L ¹¹ , R ¹¹ , L ¹² , Q ¹¹ , x ₁ ,
y ₁ , z ₁ , k and h have the same meanings as in formula (I). )

Next, the general formula (II) will be described. R
²¹ represents an alkyl group, or an alkyl group substituted with an alkyl, alkoxy, aryl, or halogen,
W ²¹ preferably represents an alkyl group, an alkyl group, an alkoxy group, an aryl group substituted with a halogen, or an alkoxy group substituted with an alkyl group, an alkoxy group, an aryl group or a halogen.

R ²¹ represents an alkyl group substituted by vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy, and W ²¹ represents an alkyl group, alkyl, alkoxy, aryl, halogen, vinyl, Alkyl groups substituted by vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy,
An alkoxy group, or alkyl, alkoxy, aryl,
It preferably represents an alkoxy group substituted by halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy.

The number of carbon atoms of the alkyl or alkoxy group is preferably from 1 to 24, and particularly preferably from 1 to 12. Examples of the alkyl group include an unsubstituted alkyl group (eg, methyl, ethyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n- Dodecyl, i-propyl,
i-butyl, sec-butyl, t-amyl and 2-ethylhexyl), an alkyl group substituted with 1-4 alkoxy (for example, 2-methoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- [2 -(2-methoxyethoxy) ethoxy] ethyl, 2-n-butoxyethyl, 2-
Ethoxyethyl, 2- (2-ethoxyethoxy) ethyl, 3-methoxypropyl, 3-ethoxypropyl,
-N-propyloxypropyl, 3-benzyloxypropyl and 2-methylbutyloxymethyl), aralkyl groups (e.g., 2-phenylethyl and 2- (4-
n-butyloxyphenyl) ethyl), a vinylalkyl group (eg, vinylmethyl, 2-vinylethyl, 5-vinylpentyl, 6-vinylhexyl, 7-vinylheptyl and 8-vinyloctyl), a vinyloxyalkyl group (eg, 2-vinyloxyethyl, 5-vinyloxypentyl, 6-vinyloxyhexyl, 7-vinyloxyheptyl and 8-vinyloxyoctyl), oxiranylalkyl group (for example, 3,4-epoxybutyl,
4,5-epoxypentyl, 5,6-epoxyhexyl, 6,7-epoxyheptyl, 7,8-epoxyoctyl and 6,7-epoxyoctyl), acryloyloxyalkyl groups (for example, 2-acryloyloxyethyl, 3 -Acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl,
6-acryloyloxyhexyl, 7-acryloyloxyheptyl and 8-acryloyloxyoctyl), methacryloyloxyalkyl groups (for example, 2-
Methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl and 8-methacryloyloxyoctyl), crotonoyloxyalkyl group (for example, 2 -Crotonoyloxyethyl, 3-crotonoyloxybutyl, 4-crotonoyloxybutyl, 5-crotonoyloxypentyl, 6
-Crotonoyloxyhexyl, 7-crotonoyloxyheptyl and 8-crotonoyloxyoctyl).

The substitution position of OR ^{21 with} the benzene ring is preferably the 3- or 4-position. The polyvinyl alcohol derivative having the group represented by the general formula (II) is used as a repeating unit having the group represented by the general formula (II) in an amount of 0.1 to 10 mol% of all the repeating units.
(Particularly in the range of 0.1 to 5 mol%). The group of the general formula (II) is represented by the following general formula (IIa)
By reacting a carboxylic acid derivative having the group (1) with polyvinyl alcohol, it can be introduced into polyvinyl alcohol.

[0031]

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In the general formula (IIa), R ²¹ , W ²¹ , n
And q are as defined in general formula (II), and X
Is necessary to form a carboxylic acid site activated form (X-
CO- can be activated). The group represented by X is described in, for example, "Peptide Synthesis (Chapter 5, Maruzen 1975)" by Nobuo Izumiya. For example, when an active ester is formed, examples of X include 4-nitrophenoxy and N-oxysuccinimide. In the case of forming an acid anhydride, a symmetrical acid anhydride and a mixed acid anhydride can be mentioned. As X in the case of the mixed acid anhydride, for example, methanesulfonyloxy, trifluoroacetyloxy, ethyloxy Carbonyloxy can be mentioned. X in the case of an acid halide includes, for example, a chlorine atom and a bromine atom. These compounds having the atom group represented by X do not necessarily need to be isolated, and those generated in the reaction system may be used as they are. As the carboxylic acid derivative, mixed acid anhydrides and acid halides are preferable, and methanesulfonyloxy type mixed acid anhydrides and acid chlorides are particularly preferable.

When X is OH (that is, in the form of an acid), examples of the compound of the general formula (IIa) are shown below.

[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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In the present invention, the substituent introduced into the polymer chain (carbon atom) of polyvinyl alcohol includes:
Particularly, a substituent represented by the following general formula (IV) is preferable.

[0042]

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In the general formula (IV), L ⁴¹ represents an atom group necessary for forming a urethane bond, an acetal bond or an ester bond, and R ⁴¹ represents a vinyl, acryloyl, methacryloyl, crotonoyl group, styryl, oxiranyl or aziridinyl. Represents (especially acryloyl or methacryloyl), j and e are each 0 or 1
And d represents an integer of 2 to 24 (particularly 2 to 10).
And u represents an integer of 0 to 4.

Next, the polyvinyl alcohol derivative represented by the general formula (III) will be described. L ³¹ represents an ether bond, a urethane bond, an acetal bond or an ester bond, and A ³¹ represents an arylene group or a halogen,
Represents an arylene group substituted by alkyl, alkoxy or substituted alkoxy (substituents of the substituted alkoxy include alkoxy, aryl, halogen, vinyl, vinyloxy, acryloyl, methacryloyl, crotonoyl, acryloyloxy, methacryloyloxy,
Crotonoyloxy, vinylphenoxy, vinylbenzoyloxy, styryl, 1,2-epoxyethyl, 1,
2-epoxypropyl, 2,3-epoxypropyl,
1,2-iminoethyl, 1,2-iminopropyl or 2,3-iminopropyl), R ³¹
Represents the same group as R ¹¹ , L ³² represents the same group as L ¹² , Q ³¹ represents the same group as Q ^11, and x ₂ + y
At ₂ + z ₂ = 100 conditions, x ₂ is 10 to 99.9 mol%, y ₂ is 0.01 to 80 mol%, and z ₂ is 0-7
0 mol%, and k ₁ and h ₁ are each 0 or 1), particularly A ³¹ is an arylene group having 6 to 24 carbon atoms, or a halogen, an alkyl having 1 to 4 carbon atoms or a carbon atom. It is preferably an arylene group having 6 to 24 carbon atoms substituted with alkoxy having 1 to 4 atoms.

[0045] In group A ^31, carbon atoms arylene group is generally 6-24 carbon atoms, 6-12 are preferred. Examples of the arylene group include 1,4-phenylene,
1,3-phenylene, 1,2-phenylene and 1,5-phenylene
Naphthylene can be mentioned, and 1,4-phenylene is particularly preferable. Examples of the substituent of the arylene group include a halogen atom (F, Cl, Br or I), an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. Aryl having 6 to 15 carbon atoms, halogen, vinyl, vinyloxy, oxiranyl (1,2-epoxyethyl, 1,2-epoxypropyl, 2,3-epoxypropyl), aziridinyl (1,2-iminoethyl, 1,2 -Iminopropyl or 2,3-iminopropyl), acryloyl, methacryloyl, crotonoyl, acryloyloxy, methacryloyloxy, crotonoyloxy, vinylphenoxy,
Examples thereof include an alkoxy group having 1 to 4 carbon atoms and substituted with vinylbenzoyloxy or styryl.
It is preferably a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and particularly preferably F, Cl or methyl.

X_Two+ Y_Two+ Z_Two= 100
_TwoIs preferably 50 to 99.9 mol%, and y_TwoIs 0.01
Is preferably 50 to 50 mol% (particularly 0.01 to 20 mol%
Preferred, especially 0.01 to 10 mol%, most preferably
0.01 to 5 mol%) and z _TwoIs 0.01 to 50 mol%
Is preferred. In the above general formula (III), L³¹Is an acetater
Is a polyvinyl alcohol of the general formula (III)
Can be represented by the following general formula (IIIa):
You.

[0047]

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(However, A ³¹ , R ³¹ , L ³² , Q ³¹ , x ₂ ,
y ₂ , z ₂ , k ₁ and h ₁ have the same meaning as in the general formula (III). The compound having a group to be introduced into polyvinyl alcohol or modified polyvinyl alcohol (for example, the compound represented by the general formula (II)
By reacting a)) with polyvinyl alcohol, a polyvinyl alcohol derivative having a specific group of the present invention can be obtained.

For use in the reaction with the compound having the above specific group.
Polyvinyl alcohol or modified polyvinyl alcohol used
The coal is generally of a saponification degree of 70-100%.
Examples include unmodified polyvinyl alcohol
And modified polyvinyl alcohol (modified group
Then, for example, -COONa, -Si (OH)_Three, -N
(CH_Three)_Three・ Cl, -C₉H₁₉COO, -SO_ThreeNah
Or -C₁₂H_{twenty five}Etc. have been introduced)
Modified polyvinyl alcohol (as a modifying group, for example,
For example, -COONa, -SH or C₁₂H_{twenty five}S- etc.
And poly) modified by block polymerization
Vinyl alcohol (as a modifying group, for example, -COO
H, -CONH_Two, -COOR (R: alkyl) or
Is -C₆H _FiveHave been introduced)
You. The degree of polymerization is in the range of 100 to 3000
preferable. The degree of saponification is preferably in the range of 80-100%
And a saponification degree of 85 to 95% is particularly preferable. Also the degree of polymerization
Therefore, the range of 100 to 3000 is preferable. Of the present invention
Examples of preferred polyvinyl alcohol derivatives are shown below.
You.

[0050]

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In the above general formula V-1, x, y and z
Is shown below. ────────────────────────────────── xyz (mol%) (mol%) (mol%) ─ポ リ マ ー Polymer No. 1 86.3 1.7 12 Polymer No. 2 85. 0 3.012 Polymer No. 3 87.7 0.312 Polymer No. 4 70.0 18.0 12 Polymer No. 5 86.9 1.1 12 Polymer No. 6 98.5 0.51 Polymer No. 7 97.8 0.22 Polymer No. 8 96.5 2.5 1 Polymer No. 9 94.9 4.1 1 ────────────────

[0052]

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In the above general formula V-2, x, y and z
Is shown below. ────────────────────────────────── xyz (mol%) (mol%) (mol%) ─ポ リ マ ー Polymer No. 10 86.3 1.7 12 Polymer No. 11 81. 7 0.3 18 Polymer No. 11a 87.7 0.312 Polymer No. 12 83.0 5.0 12 Polymer No. 13 89.0 10.0 1 Polymer No. 13a 78.0 10.0 12 ─ ─────────────────────────────────

[0054]

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In the general formula V-3, examples of n, x, y and z are shown below. Ｎ nxyz (mol%) (mol%) (mol%)ポ リ マ ー Polymer No. 14 2 80.3 1.7 18 Polymer No. 15 387.5 0.512 Polymer No. 164 94.0 5.0 1 Polymer No. 16a4 83.0 5.0 12 Polymer No. 175 86.9 1.1 12 Polymer No. 18 6 87 0.7 0.3 12 mm

[0056]

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In the general formula V-4, examples of n, x, y and z are shown below. Ｎ nxyz (mol%) (mol%) (mol%) ────────────────────────────────── Polymer No. 19 288.7 8 0.2 12 Polymer No. 20 287.5 0.512 Polymer No. 21 394.4 0.65 Polymer No. 21a 3 87.4 0.612 Polymer No. 22 4 86.4 1.612 Polymer No. 23 5 96 2.0 2.0 2 Polymer No. 23a5 86.0 2.012 Polymer No. 24 684.8 3.2 12 { ──────────────

[0058]

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In the above general formula V-5, examples of n, x, y and z are shown below. Ｎ nxyz (mol%) (mol%) (mol%) ────────────────────────────────── Polymer No. 25 2 87.5 0.5 12 Polymer No. 26 3 97.4 0.6 2 Polymer No. 26a 3 87.4 0.612 Polymer No. 274 86.4 1.6 12 Polymer No. 28 5 80.0 2.0 18 Polymer No. 29 6 84 .8 3.2 12 ──────────────────────────────────

[0060]

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In the above general formula V-6, examples of Y, x, y and z are shown below. ────────────────────────────────── Yxyz (mol%) (mol%) (mol%) ────────────────────────────────── Polymer No. 30 No. 30 -Y 86.3 1.7 12 Polymer No. 31 No. 31 -Y 97.3 1.7 1 Polymer No. 32 No. 32 -Y 87.4 0.6 12 Polymer No. 33 No. 33 -Y 80.8 1.2 18 Polymer No. . 34 No.34 -Y 86.3 1.7 12──────────────────────────────────

[0062]

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[0063]

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In the above general formula V-7, x, y and z
Is shown below. ────────────────────────────────── xyz (mol%) (mol%) (mol%) ─ポ リ マ ー Polymer No. 35 87.8 0.2 12 Polymer No. 36 88. 0 0.003 12 Polymer No. 37 87.86 0.14 12 Polymer No. 38 87.94 0.06 12 Polymer No. 39 87.2 0.812 Polymer No. 40 98.5 0.51 Polymer No. 41 97.8 0.22 Polymer No. 42 96.5 2.5 1 Polymer No. 43 94.9 4.1 1 Polymer No. E 86.9 1.1 12 Polymer No. F 98.5 0.5 1──────────────────────────────────

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In the general formula V-8, examples of n, x, y and z are shown below. Ｎ nxyz (mol%) (mol%) (mol%)ポ リ マ ー Polymer No. 44 3 87.8 0.212 Polymer No. 45 5 87.85 0.15 12 Polymer No. 46 6 87.7 0.312 Polymer No. 478 87.7 0.312 ────────────────

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In the general formula V-9, examples of Y, x, y and z are shown below. ────────────────────────────────── Yxyz (mol%) (mol%) (mol%) ────────────────────────────────── Polymer No. 48 No. 48-Y 96.2 1.8 2 Polymer No. 49 No. 49 -Y 84.2 0.815 Polymer No. 50 No. 50 -Y 84.9 3.112 Polymer No. 51 No. 51 -Y 87.5 2.5 10 ── ────────────────────────────────

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[0070]

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In the above general formula V-10, n, x, y
Examples of z and z are shown below. ────────────────────────────────── nR xyz (mol%) (mol%) (mol% ) ポ リ マ ー Polymer No. 52 6H 86.4 1.6 12 Polymer No. 534 H 87.2 0.812 Polymer No. 544 H 84.7 3.312 Polymer No. 555 CH ₃ 78.8 6.215 Polymer No. 569 CH ₃ 94.2 3. 82 Polymer No. 573 H 85.0 5.0 10}

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In the above general formula V-11, n, x, y
Examples of z and z are shown below. ────────────────────────────────── nR xyz (mol%) (mol%) (mol% ) ────────────────────────────────── Polymer No. 58 2 H 87.5 2.5 10 Polymer No. 594 H 84.5 0.515 Polymer No. 605 CH ₃ 97.8 0.22 Polymer No. 616 CH ₃ 94.5 4.1 1 Polymer No. 629 H 97.3 1. 7 1 ──────────────────────────────────

At least one of the polyvinyl alcohol derivative represented by the general formula (I) or (III) and the group represented by the general formula (II) which can be preferably used in the present invention.
The polyvinyl alcohol derivative having one hydroxyl group substituted can be synthesized by the method described in EP 726,486A2. The liquid crystal compound-containing layer forming the element having the alignment film of the present invention is preferably made of a discotic liquid crystal compound.

When the element of the present invention is used as an optical compensation sheet, the polyvinyl alcohol-based polymer of the present invention, a bifunctional aldehyde compound capable of cross-linking the polymer, and a cross-linked hardened film are effectively provided on a transparent support. A coating solution containing an acid that acts on the coating solution is applied, heated and dried, and then subjected to a rubbing treatment to form an alignment film. Then, a coating solution containing a liquid crystal compound, particularly a discotic liquid crystal compound, is coated on the alignment film. It can be advantageously obtained by heating to an optically anisotropic forming temperature and then cooling to form an optically anisotropic layer.

The element of the present invention preferably has a basic structure comprising a transparent support as described above, an alignment film provided thereon, and a layer of a discotic liquid crystalline compound formed on the alignment film. As the material for the transparent support of the present invention, any material can be used as long as it is transparent. A material having a light transmittance of 80% or more is preferable, and a material having optical isotropy when viewed from the front is particularly preferable. Therefore, the transparent support is preferably manufactured from a material having a small intrinsic birefringence. Such materials include ZEONEX (manufactured by ZEON CORPORATION), ARTO
Commercial products such as N (manufactured by Nippon Synthetic Rubber Co., Ltd.) and Fujitac (manufactured by Fuji Photo Film Co., Ltd.) can be used. Furthermore, even a material having a large intrinsic birefringence such as polycarbonate, polyarylate, polysulfone, and polyethersulfone can be obtained by appropriately setting conditions such as solution casting and melt extrusion.

When the element of the present invention is used as an optical compensation sheet, the main refractive index in the plane of the transparent support (film) is set to n.
When x, ny, the main refractive index in the thickness direction are nz, and the thickness of the film is d, the relationship between the triaxial main refractive indices is nz <ny =
nx (negative uniaxiality), and the formula ｛(nx + ny) / 2
The retardation represented by -nz で d is preferably from 20 nm to 400 nm (preferably from 30 to 150 nm). However, the values of nx and ny do not need to be exactly equal, but it is sufficient if they are approximately equal. Specifically, | nx-
If ny | / | nx-nz | ≦ 0.2, there is no practical problem. The front retardation represented by | nx−ny | × d is preferably 50 nm or less, more preferably 20 nm or less. Nx, ny, nz above
And d are shown in FIG.

An undercoat layer is preferably provided on the transparent support in order to increase the adhesive strength between the transparent support and the alignment film. Generally, gelatin is used.

An optical compensatory sheet obtained by forming an optically anisotropic layer made of a discotic liquid crystalline compound on an alignment film and having excellent optical characteristics such as viewing angle characteristics was used or stored under high temperature and high humidity, for example. In this case, there is a problem that reticulation (wrinkles in a network) occurs in the optically anisotropic layer or the optically anisotropic layer is peeled off from the alignment film. The alignment film of the present invention is an alignment film composed of a polymer obtained by crosslinking and hardening a polyvinyl alcohol-based polymer with a bifunctional aldehyde in the presence of an acid,
The above problem can be solved.

The polyvinyl alcohol polymer of the present invention may be used alone as a polymer for an alignment film,
Alternatively, it may be used as a mixture with a conventionally known polymer for an alignment film. In the case of a mixture, it is preferable to use at least 10% by weight, more preferably at least 30% by weight, of the polymer of the present invention.

The following are specific examples of the bifunctional aldehyde which is a crosslinking agent of the present invention. 1) Aliphatic bifunctional aldehydes such as glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde and adipaldehyde. 2) aromatic bifunctional aldehydes such as phthalaldehyde, isophthalaldehyde, and terephthalaldehyde; 3) Bifunctional aldehydes such as poval and dialdehyde starch at both terminal aldehydes. Of these, aliphatic bifunctional aldehydes having high reaction activity are preferred.

The following are specific examples of acids which can co-exist with the bifunctional aldehyde of the present invention to effectively act on the crosslinked cured film. 1) Inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, sulfurous acid, and carbonic acid. 2) acetic acid, propionic acid, oxalic acid, monochloroacetic acid,
Organic carboxylic acids such as dichloroacetic acid, trifluoroacetic acid, benzoic acid and salicylic acid. 3) Organic sulfonic acids such as methanesulfonic acid, benzenesulfonic acid and p-toluenesulfonic acid. Of these,
Inorganic acids are preferred, and non-volatile sulfuric acid is particularly preferred.
The addition amount of these acids may be as small as 10 μmol to 10 mmol, preferably 100 μmol to 10 mmol, per 1 g of the polyvinyl alcohol-based polymer. The addition amount of the bifunctional aldehyde tends to improve as the addition amount increases with respect to the moisture resistance. However, since the alignment ability as an alignment film is reduced when 50% by weight or more is added to the polymer, it is preferably 0.1 to 20% by weight, particularly preferably 0.5 to 15% by weight. The alignment film of the present invention contains a certain amount of a cross-linking agent that has not reacted even after the completion of the cross-linking reaction.
0% by weight or less, preferably 0.5% by weight
The following is preferred. If the cross-linking agent is contained in the alignment film in an amount exceeding 1.0 weight, sufficient durability cannot be obtained. That is, when used in a liquid crystal display device, reticulation may occur when used for a long time or when left in an atmosphere of high temperature and high humidity for a long time.

The alignment film of the present invention is basically applied on a transparent support containing the above polymer, a bifunctional aldehyde and an acid, which is an alignment film forming material, and then dried by heating (crosslinking).
And can be formed by rubbing,
The cross-linking reaction may be performed at any time after coating on the transparent support, as described above. When the polyvinyl alcohol-based polymer of the present invention is used as an alignment film forming material, the coating liquid is preferably a mixed solvent of an organic solvent such as methanol having defoaming action and water, and the ratio is a weight ratio. Water: methanol 0: 100-99: 1
Is common, and it is preferable that it is 0: 100 to 91: 9. Thereby, generation of bubbles is suppressed, and defects on the alignment film and further on the surface of the optically anisotropic layer are significantly reduced. Examples of the coating method include a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. In particular, the E-type coating method is preferable. The thickness is preferably 0.1 to 10 μm. Heat drying is 2
It can be performed at 0 ° C to 110 ° C. In order to form a sufficient crosslink, the temperature is preferably from 60C to 100C, particularly preferably from 80C to 100C. Drying time is 1 minute to 36
Can be done in time. Preferably 5 minutes to 30
Minutes.

The discotic liquid crystalline compounds which can be preferably used in the present invention include benzene derivatives and triphenylenes described in The Chemical Society of Japan, Quarterly Review of Chemistry, No. 22, Liquid Crystal Chemistry (1994). Derivatives, truxene derivatives, phthalocyanine derivatives, porphyrin derivatives, anthracene derivatives, azacrown derivatives, cyclohexane derivatives, β-diketone-based metal complex derivatives, and phenylacetylene macrocycles. Further, the Chemical Society of Japan, “Chemical Review No. 15 , New Aromatic Chemistry "(1977, published by The University of Tokyo Press) and their heteroatom-substituted isoelectronic structures. Further, as in the case of the above-described metal complex, an assembly of a plurality of molecules may be formed by hydrogen bonding, coordination bond, or the like to form a disk-shaped molecule.

The discotic (disk-like) liquid crystal compound has a discotic structure as a central nucleus of a molecule, and linear alkyl groups, alkoxy groups, substituted benzoyloxy groups and the like are radially substituted as side chains. Having a structure. The core compound preferably forms a discotic nematic (N _D ) phase, and particularly preferably includes triphenylene and truxene. Examples of the side chain include an alkyl group, an alkoxy group, an alkylthio group, an acyloxy group, an alkoxycarbonyl group, and a halogen, and an alkyl group, an alkoxy group, an alkylthio group, and an acyloxy group are particularly preferable. These groups are described in C. Hansch, A. Leo, RWTaf
t, Chemical Review Magazine (Chem. Rev.), 1991, 9
1, pp. 165-195 (American Chemical Society). Further in the side chain, for example, an ether group, an ester group, a carbonyl group, a thioether group, a sulfoxide group,
It may contain a functional group such as a sulfonyl group or an amide group, or an aryl group or a heterocyclic group in the side chain.

The discotic liquid crystalline compound of the present invention can form a new bond in itself as a substituent, or can bond to another compound (same or different), and It is preferable that the polymer has a group capable of chemically bonding to the polymer. Such groups react with the same group to form a new bond, or react with a different group to form a new bond. Examples of such groups are described in Organic Functional Group Preparations by SR Sandler and W. Karo.
(Organic Functional Group Preparations), Volumes 1 and 2 (Academic Press, New York, London, 1968). Among them,
A polymerizable group is preferable, for example, a multiple bond (a constituent atom may be a carbon atom or a non-carbon atom), oxirane,
Heterocyclic rings such as aziridine are preferred, and RAM
Hikmet et al. [Macromolecules, 25, 419
4 (1992)] and [Polymer, Vol. 34, No. 8, 17,
63 (1993)], a research report by DJ Broer et al. [Ma
cromolecules, 26, 1244 (1993)] are preferred. Preferred examples of the discotic liquid crystalline compound include the following.

[0087]

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In the above D-1-1, R ⁶¹ , R ⁶² ,
Examples of R ⁶⁴ , R ⁶⁵ , R ⁶⁶ and J are shown below. ──────────────────────────────────── Compound R ⁶¹ R ⁶² R ⁶⁴ R ⁶⁵ R ⁶⁶ J ── ────────────────────────────────── TP-1 HHHHH-(CH ₂ ) ₂ OCO- TP-2 HHHHH _{- (CH 2) 3 OCO- TP} -3 HHHHH - (CH 2) 4 OCO- TP-4 HHHHH - (CH 2) 5 OCO- TP-5 HHHHH - (CH 2) 6 OCO- TP-6 HHHHH - ( CH ₂ ) ₇ OCO- TP-7 HHHHH-(CH ₂ ) ₈ OCO- TP-8 HHHH CH _3- (CH ₂ ) ₉ OCO- TP-9 HHHHC ₂ H _5- (CH ₂ ) ₆ OCO- TP-10 _{CH 3 HHHC 2 H 5 - (} CH 2) 6 OCO- TP-11 CH 3 CH 3 HHH - (CH 2) 2 OCO- TP-12 H CH 3 HHH - (CH 2) 3 OCO- TP-13 CH 3 HHHH-(CH ₂ ) ₄ OCO- TP-14 CH ₃ HHHH-(CH ₂ ) ₅ OCO- TP-15 CH ₃ HHHH-(CH ₂ ) ₆ OCO- TP-16 CH ₃ CH ₃ HHH-(CH ₂ ) ₇ OCO- TP-17 H CH ₃ HHH-(CH ₂ ) ₈ OCO- TP-18 CH ₃ HHH CH _3- (CH ₂ ) ₉ OCO- TP-19 CH ₃ HHHC ₂ H _5- (CH ₂ ) ₆ OCO - _{P-20 H CH 3 HH CH} 3 - (CH 2) 6 OCO- TP-21 HHHH nC 3 H 7 - (CH 2) 2 OCO- TP-22 HHHHH - (CH 2) 3 OC 2 H 4 OCO- TP −23 HHHHH-(C ₂ H ₄ O) ₂ C ₃ H ₆ OCO- TP−24 CH ₃ HHHH-(C ₂ H ₄ O) ₂ CO- TP−25 HHHHH-(C ₂ H ₄ O) ₃ CO- TP-26 HHH CH ₃ CH _3- (CH ₂ ) ₄ CO- TP-27 HH CH ₃ HH-(CH ₂ ) ₅ OCO- TP-28 HH CH ₃ HH-(CH ₂ ) ₆ OCO- TP-29 HH CH ₃ HH-(CH ₂ ) ₇ OCO- TP-30 HH CH ₃ HH-(CH ₂ ) ₈ OCO- ──────────────────────── ────────────

[0089]

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[0090]

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[0091]

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[0092]

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[0093]

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[0094]

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[0096]

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[0097]

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[0098]

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[0099]

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These discotic liquid crystalline compounds can be used alone or as a mixed composition. Compounds that can be added to the discotic liquid crystalline compound include:
Discotic liquid crystalline compound having no liquid crystal properties, or other compounds (low molecular weight, high molecular weight, liquid crystalline, non-liquid crystalline, which can form new bonds between molecules or within molecules, Which may not be obtained; eg, plasticizers, polymerizable monomers, surfactants, polymers). As described above, the element of the present invention is produced by providing the above-mentioned alignment film of the present invention on a transparent support, and then forming a liquid crystal compound-containing layer on the alignment film.

When the liquid crystal compound-containing layer is an optically anisotropic layer, it is a layer having a negative birefringence made of a compound having a discotic structural unit, and the surface of the discotic structural unit is disposed on the transparent support surface. It is preferable that the angle between the surface of the discotic structural unit and the surface of the transparent support is changed in the depth direction of the optically anisotropic layer.

The angle (tilt angle) of the surface of the discotic structure unit generally increases or decreases in the depth direction of the optically anisotropic layer and as the distance from the bottom surface of the optically anisotropic layer increases. Preferably, the angle of inclination increases with increasing distance. Further, the change in the inclination angle includes a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including the continuous increase and the continuous decrease, and an intermittent change including the increase and the decrease. it can. The intermittent change includes a region where the inclination angle does not change in the thickness direction. It is preferable that the tilt angle increases or decreases as a whole, even if it includes a region that does not change. Further, the inclination angle is preferably increased as a whole, and is particularly preferably changed continuously.

FIG. 2 schematically shows a typical example of a cross section of the optically anisotropic layer of the present invention. The optically anisotropic layer 23 is provided on the alignment film 22 formed on the transparent support 21.
The liquid crystalline discotic compounds 23a, 23b, and 23c constituting the optically anisotropic layer 23 have a discotic structural unit Pa, Pb, and Pc whose surface 2 is parallel to the surface of the transparent support 21.
1a, 21b, 21c, and their inclination angles θa, θb, θc (the angles formed by the plane of the discotic structural unit and the plane of the transparent support) are equal to the depth from the bottom of the optically anisotropic layer ( It increases in order with the increase in the distance in the thickness direction. 24 represents the normal line of the transparent support. The liquid crystalline discotic compound is a planar molecule, and therefore has only one plane in the molecule, ie, a disk surface (eg, 21a, 21a).
b, 21c).

It is preferable that the inclination angle (angle) changes in a range of 5 to 85 degrees (particularly, in a range of 10 to 80 degrees). The minimum value of the inclination angle is preferably in the range of 0 to 85 degrees (particularly 5 to 40 degrees), and the maximum value is preferably in the range of 5 to 90 degrees (particularly 30 to 85 degrees). In FIG. 2, the tilt angle (eg, θa) of the discotic structure unit on the support side substantially corresponds to the minimum value, and the tilt angle (eg, θc) of the discotic structure unit substantially corresponds to the maximum value. I have. Further, the difference between the minimum value and the maximum value of the inclination angle is preferably in the range of 5 to 70 degrees (particularly, 10 to 60 degrees).

In general, the optically anisotropic layer is formed by applying a solution in which a discotic compound and another compound are dissolved in a solvent to an orientation film, drying the solution, and then heating the solution to a discotic nematic phase formation temperature. (Discotic nematic phase) is obtained by cooling. Alternatively, the optically anisotropic layer is formed by applying a solution in which a discotic compound and other compounds (for example, a polymerizable monomer and a photopolymerization initiator) are dissolved in a solvent onto an alignment film, drying, and then discotic nematic It is obtained by heating to a phase forming temperature, polymerizing (by irradiation with UV light or the like), and further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is preferably from 70 to
300 ° C is preferable, and 70 to 170 ° C is particularly preferable.

For example, the tilt angle of the discotic unit on the support side can be generally adjusted by selecting a discotic compound or a material of an alignment film, or by selecting a rubbing method. In addition, the tilt angle of the discotic unit on the surface side (air side) generally selects a discotic compound or another compound used together with the discotic compound (eg, a plasticizer, a surfactant, a polymerizable monomer and a polymer). Can be adjusted. Further, the degree of change of the inclination angle can be adjusted by the above selection.

The plasticizer, surfactant and polymerizable monomer have compatibility with the discotic compound.
Any compound can be used as long as it can change the tilt angle of the liquid crystalline discotic compound or does not hinder the alignment. Among these, a polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group) is preferable.
The above compounds are generally used in an amount of 1 to 50% by weight, preferably 5 to 30% by weight, based on the discotic compound.

As the polymer, any polymer can be used as long as it is compatible with the discotic compound and can change the tilt angle of the liquid crystalline discotic compound. Examples of the polymer include a cellulose ester. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropylcellulose and cellulose acetate butyrate. The polymer is generally 0.1 to 10% by weight (preferably 0.1 to 8% by weight, particularly 0.1 to 5% by weight) based on the discotic compound so as not to hinder the alignment of the liquid crystalline discotic compound. ).

The (color) liquid crystal display device having the optically anisotropic layer (optical compensatory sheet) having a variable tilt angle shown in FIG. 2 has a very wide viewing angle, and is capable of inverting a black-and-white image. Or the display image has almost no gradation or coloring.

The optically anisotropic layer of the present invention generally has a minimum absolute value of retardation other than 0 (has no optical axis) in a direction inclined from the normal direction of the support. FIG. 3 shows a typical configuration example of an element including the orientation of the present invention. In FIG. 3, a transparent support 41, an alignment film 42, and a discotic compound layer (optically anisotropic layer) 43 are sequentially laminated. R indicates the rubbing direction of the alignment film. n
₁ , n ₂ and n ₃ represent the refractive indices of the optical compensatory sheet in the triaxial directions, and satisfy the relationship of n ₁ ≦ n ₃ ≦ n ₂ when viewed from the front. β is the inclination from the normal line 44 of the optically anisotropic layer in the direction showing the minimum value of Re (retardation). In order to improve the viewing angle characteristics of the TN-LCD and the TFT-LCD, the direction showing the minimum value of the absolute value of Re is inclined from the normal line 44 of the optically anisotropic layer by 5 to 50 degrees (the average value of the inclination). And more preferably 10 to 40 degrees (the above β). Further, the sheet has the following conditions: 50 ≦ [(n ₃ + n ₂ ) / 2−n ₁ ] × D ≦ 400 (n
m) (however, the thickness of the D sheet) is preferably satisfied,
Further, the following condition: 100 ≦ [(n ₃ + n ₂ ) / 2−n ₁ ] × D ≦ 400
(Nm) is preferably satisfied.

The solution for forming the optically anisotropic layer can be prepared by dissolving the discotic compound and the other compound described above in a solvent. Examples of the solvent include polar solvents such as N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) and pyridine; non-polar solvents such as benzene and hexane; alkyl halides such as chloroform and dichloromethane; Esters such as methyl and butyl acetate; ketones such as acetone and methyl ethyl ketone; and ethers such as tetrahydrofuran and 1,2-dimethoxyethane. Alkyl halides and ketones are preferred. The solvents may be used alone or in combination.

The solution can be applied by curtain coating, extrusion coating, roll coating,
Examples include dip coating, spin coating, print coating, spray coating and slide coating. In the present invention, in the case of a mixture of only discotic compounds, a vapor deposition method can also be used. In the present invention, continuous coating is preferred. Therefore, curtain coating, extrusion coating, roll coating and slide coating are preferred. As described above, the optically anisotropic layer is obtained by applying the coating solution on the alignment film, drying the coating solution, and then heating it to a temperature equal to or higher than the glass transition temperature (then, if necessary, hardening) and cooling.

The element of the present invention relates to a liquid crystal display device,
When used as an optical compensation sheet for compensating birefringence by a liquid crystal cell, it is preferable that the wavelength dispersion of the optically anisotropic element is equal to that of the liquid crystal cell. That is, 45 of the optically anisotropic element
The retardation due to light of 0,550 μm is R
_450, if R _550, R ₄₅₀ / R ₅₅₀ representing the chromatic dispersion
The value is preferably 1.0 or more.

FIG. 4 shows a typical configuration example of a liquid crystal display device having the elements of the present invention. In FIG. 4, a liquid crystal cell TNC comprising a pair of substrates provided with transparent electrodes and a twist-aligned nematic liquid crystal sealed between the substrates, a pair of polarizing plates A and B provided on both sides of the liquid crystal cell, and a liquid crystal cell The optical compensation sheets RF ₁ , RF ₂ and the backlight BL arranged between the liquid crystal display device and the polarizing plate constitute a liquid crystal display device. Only one optical compensation sheet may be provided (ie, RF ₁ or RF ₂ ). R ₁ indicates the rubbing direction of the optical compensation sheet RF ₁ when viewed from the front, and R ₂ indicates the rubbing direction of the optical compensation sheet RF ₂ . The solid line arrow of the liquid crystal cell TNC indicates the rubbing direction of the substrate on the polarizing plate B side of the liquid crystal cell, and the dotted arrow of the liquid crystal cell TNC indicates the rubbing direction of the substrate on the polarizing plate A side of the liquid crystal cell. PA and PB are polarizing plates A and B, respectively.
Represents the polarization axis.

As described above, the element of the present invention can be usefully used as an optical compensation sheet in a liquid crystal display device. Further, it can be used for the purpose of aligning the liquid crystal of the liquid crystal display element.

[0116]

[Examples 1 to 20 and Comparative Examples 1 to 6]

(Preparation of alignment film) The following coating solution containing polyvinyl alcohol shown in Table 2 described below was coated on a triacetyl cellulose film (100 μm thick, Fuji Tack Co., Ltd., Fuji Tack Co.) using a bar coater. It was dried by heating for 10 minutes to form a polymer layer having a thickness of 0.8 μm. (Hereinafter, "parts" means "parts by weight") [Coating liquid] Polyvinyl alcohol-based polymer shown in Table 1 1.0 part Water 18.0 parts Methanol 6.0 parts Bifunctional aldehyde 0.05 part Acid 0.01 part The surface of the obtained polymer layer was coated with a rubbing roll outer diameter of 8
0 mm, film transport speed: 100 m / min, rubbing roll rotation speed: 1000 rpm, and film transport tension: 1 kgf /
A rubbing treatment was performed under the condition of a cm substrate width to form an alignment film.

(Layer of Discotic Liquid Crystalline Compound (Optical Anisotropic Layer)
Formation of) A coating liquid for forming a discotic liquid crystalline compound layer having the following composition is coated on a rubbed alignment film on a film by a bar coater, and dried to obtain a discotic liquid crystalline compound. A coating layer was formed. [Coating liquid] Cellulose acetate butyrate 12 parts (CAB531, manufactured by Eastman Chemical Company) Discotic liquid crystal compound TP-3 (the above-mentioned compound) 100 parts Tripropylene glycol diacrylate 10 parts (SR306, manufactured by Somar Co., Ltd.) Polymerization initiator 2 parts (Irgacure 907, manufactured by Nippon Ciba Geigy Co., Ltd.) 400 parts of methyl ethyl ketone The film having the coating layer is passed through a heating zone at 140 ° C. for 2 minutes, and then the coating layer is irradiated with UV light to be cured. As a result, a thin film (optically anisotropic layer, layer thickness: 2 μm) in which the aligned state of the aligned discotic liquid crystal compound was fixed was formed, and an optical compensation sheet was obtained.

(Evaluation of Orientation of Disc-shaped Liquid Crystal Compound Layer (Optical Anisotropic Layer) Before and After Moisture Heat Resistance Test) A film provided with an alignment film and an optically anisotropic layer was placed on a hot stage (FP82).
Polarizing microscope (OPTI) while heating on a mold, METTLER
Using PHOT-POL, manufactured by Nippon Kogaku Co., Ltd., the orientation state of the optically anisotropic layer was observed. Examples 1 to 20 and Comparative Example 1
The optically anisotropic layers obtained in Nos. 6 to 6 looked bright even under crossed Nicols, and showed optical anisotropy. The above observation results of the obtained optically anisotropic layer are shown in Tables 1 and 2. Furthermore, the orientation of the obtained film was left for 300 hours under the conditions of 90 ° C. and 95% humidity, and then observed in the same manner as described above to evaluate the wet heat resistance. The obtained results are shown in Tables 1 and 2.
The evaluation of the orientation was performed as follows. A: Uniform orientation B: Schlieren structure remaining The evaluation of wet heat resistance was performed as follows. A: Uniform orientation B: Occurrence of reticulation after 150 hours of moist heat test C: Occurrence of reticulation after 100 hours of moist heat test D: Occurrence of reticulation after 50 hours of moist heat test E: 5 hours of moist heat test Post reticulation occurs

[0119]

[Table 1]

[0120]

[Table 2]

[0121]

The optical compensatory sheet of the present invention comprising an alignment film obtained by crosslinking and curing a polyvinyl alcohol-based polymer with a bifunctional aldehyde in the presence of an acid,
It can be seen that reticulation hardly occurs during storage under conditions of high temperature and high humidity, and that it has excellent moist heat resistance.

[Brief description of the drawings]

FIG. 1 shows a main refractive index nx in the plane of a transparent support (film),
It is a figure which shows roughly the relationship of ny and the main refractive index nz of the thickness direction.

FIG. 2 is a view showing a typical structure of an optically anisotropic layer of the optical compensation sheet of the present invention.

FIG. 3 is a diagram schematically showing the relationship between a typical configuration of an optical compensation sheet of the present invention and triaxial principal refractive indices.

FIG. 4 is a diagram showing a typical structure of a liquid crystal display device of the present invention.

[Explanation of symbols]

21, 41 Transparent support 22, 42 Orientation film 23, 43 Optically anisotropic layer 23a, 23b, 23c Liquid crystalline discotic compound Pa, Pb, Pc Surface of discotic structural unit 21a, 21b, 21c Surface of transparent support 21 Θa, θb, θc Inclination angle 24 Normal line of transparent support

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[Procedure amendment]

[Submission date] April 9, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The unmodified polyvinyl alcohol has, for example, a saponification degree of 70 to 100%, generally has a saponification degree of 80 to 100%, and more preferably has a saponification degree of 8 to 100%.
5 to 95%. The degree of polymerization is 100-3
A range of 000 is preferred. As the modified polyvinyl alcohol, those modified by copolymerization (for example, COONa, Si (OH) ₃ , N (CH ₃ ) ₃ .C
1, C ₉ H ₁₉ COO, SO ₃ Na, C ₁₂ H _{25 and the} like are introduced), and those modified by chain transfer (as modifying groups,
For example, COONa, SH, SC ₁₂ H _{25 and the} like are introduced), and those modified by block polymerization (for example, COOH, CONH ₂ , COOR, C ₆
H ₅ and the like can be mentioned modified product of polyvinyl alcohol to) such introduction. The degree of polymerization is 100 to 30
The range of 00 is also preferable. Of these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferred, and unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% is more preferred.

Claims (5)

[Claims] 1. A transparent support, an alignment film made of a polyvinyl alcohol-based polymer, and a layer made of a liquid crystal compound are provided in this order, and the polyvinyl alcohol-based polymer is a bifunctional aldehyde compound in the presence of an acid. An element characterized in that it is a polymer crosslinked and hardened by the above. 2. The element according to claim 1, wherein said liquid crystalline compound is a discotic liquid crystalline compound. 3. The method according to claim 2, wherein the polyvinyl alcohol-based polymer is
The element according to claim 1, which is a polymer represented by the following general formula (I). General formula (I) (However, L ¹¹ is an ether bond, a urethane bond, an acetal bond or an ester bond, R ¹¹ represents an alkylene group, L ¹² represents a linking group connecting the R ¹¹ and Q ^11, Q ¹¹ is , Vinyl, oxiranyl or aziridinyl, where x ₁ is 10 to 99.9 mol% and y ₁ is 0.01 to 8 under the condition of x ₁ + y ₁ + z ₁ = 100.
0 mol%, and z ₁ is 0-70 mol%, and k
And h are each 0 or 1. ) 4. The method according to claim 1, wherein the polyvinyl alcohol-based polymer is
The element according to claim 1, wherein the element is a polyvinyl alcohol derivative in which at least one hydroxyl group is substituted with a group represented by the following general formula (II). General formula (II) (However, R ²¹ represents an alkyl group or an alkyl group substituted with an alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy; W ²¹ represents an alkyl group; Alkyl, alkoxy,
Aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy-substituted alkyl group, alkoxy group, or alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or Represents an alkoxy group substituted with crotonoyloxy, q is 0 or 1, and n is an integer of 0-4. ) 5. The polyvinyl alcohol-based polymer,
The element according to claim 1, which is a polymer represented by the following general formula (III). General formula (III) (However, L ³¹ represents an ether bond, a urethane bond, an acetal bond or an ester bond, A ³¹ represents an arylene group, R ³¹ represents an alkylene group,
³² represents a linking group connecting R ³¹ and Q ³¹ , Q ³¹ represents vinyl, oxiranyl or aziridinyl, and x ₂
+ Y ₂ + z ₂ = 100, x ₂ is 10-99.
9 mol%, y ₂ is 0.01 to 80 mol%, and z ₂ are 0 to 70 mol%, k _1, h ₁ and f are each 0 or 1. )