JP3432572B2 - Liquid crystal oligomer polymer film, method for producing the same, retardation plate and liquid crystal display device using liquid crystal oligomer polymer film - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an oriented liquid crystal oligomer polymer film useful as a member of a retardation film used in a liquid crystal display device, a method for producing the same, a laminate of the oriented liquid crystal oligomer polymer film and a substrate, The present invention relates to a composite retardation film including the uniaxially oriented retardation film and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A retardation film is a polymer film having optical homogeneity and durability and having uniaxial orientation,
It is generally used as an optical compensation plate for improving the display quality of liquid crystal display elements. A super twist nematic (hereinafter sometimes referred to as STN) type liquid crystal display device using a retardation film has advantages such as light weight, thinness, and low cost, but has poor viewing angle characteristics and poor black and white level. Had the disadvantages such as. These disadvantages have been considerably improved by a method such as laminating two retardation films, but the viewing angle characteristics have not yet reached a satisfactory level.

The viewing angle characteristics of the liquid crystal display device are largely correlated not only with the angle dependency of the birefringence of the liquid crystal cell for display but also with the angle dependency of the retardation of the retardation film. It is known that the smaller the change in retardation angle, the better. For this purpose, it has been proposed to vertically align a liquid crystalline material and use a retardation film having a high refractive index in the direction normal to the film surface. JP-A-2-73327 and JP-A-2-73327
No. 105111 discloses that the in-plane refractive index is isotropic in order to reduce the angle change of the background color of a uniaxially oriented birefringent body (liquid crystal cell for display) having positive refractive index anisotropy. However, a method using a birefringent layer having a refractive index in the thickness direction larger than the in-plane refractive index is disclosed. As a material having such a refractive index anisotropy, a homeotropic (vertical) oriented compensating liquid crystal cell is exemplified.

Further, in JP-A-2-256023, by using a film having an optical axis in the direction normal to the film surface and a retardation film having a positive birefringence value, the angle change of retardation is changed. It is described that the retardation film can be obtained and the viewing angle characteristics are improved. As a film having an optical axis in the normal direction of the film, a photopolymerizable compound and a liquid crystal monomer are mixed, and while maintaining the alignment of the liquid crystal monomer in an electric field, the polymerization proceeds and the alignment in the normal direction is fixed. How to do is listed.

In Japanese Patent Application Laid-Open No. 4-16916, a birefringent layer having a refractive index in the thickness direction larger than the in-plane refractive index is used.
It is disclosed that the birefringent layer is composed of a vertically aligned polymer liquid crystal. Regarding the method of vertically aligning polymer liquid crystals, after heating to the liquid crystal temperature, applying an electric field or magnetic field in the thickness direction, and sandwiching it with two substrates whose surfaces are treated with a vertical aligning agent such as a silane compound. A method of vertically aligning at a liquid crystal temperature is disclosed, and it is shown that a retardation film excellent in viewing angle characteristics can be obtained by combining with a retardation film obtained by stretching a polymer. On the other hand, polyvinyl alcohol, which is a polymer having a hydroxyl group in the side chain, is used as a horizontal alignment film of liquid crystal in a liquid crystal display device, is applied on the substrate of a transparent electrode, and is rubbed to horizontally align liquid crystal molecules. It is known to cause.

However, it is not known that the optical axis of a polymer laminated film obtained by laminating a liquid crystal oligomer and a hydrophilic substrate or a polymer substrate treated with a hard coat is substantially parallel to the normal direction. Further, regarding a composite retardation film of a polymer liquid crystal / polymer laminated film and a retardation film, in the conventional method, when a film having an optical axis in the normal direction of the film and a retardation film are combined, In order to have the optical axis in the normal direction, while maintaining the orientation of the liquid crystal monomer having a large orientation relaxation, photopolymerization, an external field such as an electric field or a magnetic field is required,
An operation of sandwiching between the two substrates which were made hydrophobic and peeling was required. For high molecular weight liquid crystals, the alignment method is complicated, and for low molecular weight liquid crystals, it is difficult to fix the alignment. As described above, the conventional method has a problem that an industrially advantageous manufacturing method has not been established.

[0007]

The object of the present invention is to provide an oriented liquid crystal oligomer polymer film which gives a wide viewing angle, an industrially advantageous method for producing the film, a wide viewing angle, and an excellent black and white level. It is an object of the present invention to provide a laminate of the film and a retardation film, a composite retardation plate, and a liquid crystal display device using the same, in which the viewing angle characteristics are remarkably improved and the black and white level is excellent.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a liquid crystal oligomer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase is homeotropically aligned. After that, it was found that the alignment can be fixed by polymerizing, and alignment liquid crystal oligomer polymerization that has an optical axis almost parallel to the normal direction of the substrate surface on a hydrophilic substrate or a hard-coated polymer film. Liquid crystal display device can be obtained, and by further combining the oriented liquid crystal oligomer polymer film with a retardation film having uniaxial orientation, a liquid crystal display device having an excellent black-and-white level and good viewing angle characteristics can be obtained. This has led to the completion of the present invention.

That is, the present invention comprises the following inventions. [1] A film composed of a polymer of a liquid crystal oligomer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase, wherein the liquid crystal oligomer has the following repeating units (I) and (II) as main constituent units. Selected from linear or cyclic liquid crystal oligomers, the number of repeating units (I) and (II) in one molecule of the oligomer is n and n ′, respectively.
And n and n ′ are each independently 1 to 20
And 4 ≦ n + n ′ ≦ 21, the terminal group of the repeating unit (II) is polymerized, and the optical axis of the film is substantially parallel to the normal direction of the film. Aligned liquid crystal oligomer polymer film.

[Chemical 6]

[Chemical 7] [Wherein A is a group represented by the following formula (III) or (IV), and in formula (III), -Si-O- is represented by formula (I).
Or the main chain of (II), and in the formula (IV), -C
—CH ₂ — is the backbone of formula (I) or (II),
The OO group is located on a side chain that is not R ₁ or R ₂ of the side chain. When A is formula (III) in formula (I) and A is formula (III) in formula (II), R ₁ and R ₂ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms or phenyl. It is a base. In formula (I), when A is formula (IV), and in formula (II), A is formula (I)
In the case of V), R ₁ and R ₂ independently represent hydrogen or 1 to 1 carbon atoms.
6 is an alkyl group.

[Chemical 8]

[Chemical 9] k and k'independently represent an integer of 2 to 10, m and m'independently represent 0 or 1, and Ar ₁ , Ar ₂ , A
r ₃ and Ar ₄ are independently a 1,4-phenylene group, 1,
4-cyclohexane group, pyridine-2,5-diyl group,
Pyrimidine-2,5-diyl group, L and L '-CH ₂ independently _{-O -, - O-CH 2} -, - COO -, - O
_{CO -, - CH 2 -CH 2} -, - CH = N -, - N = C
H- or

[Chemical 10] Is a divalent group represented by, p and p ′ are independently 0 or 1, R is a halogen, a cyano group, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, R'is hydrogen or an alkyl group having 1 to 5 carbon atoms. ]

[2] A linear or cyclic liquid crystal oligomer comprising the repeating units (I) and (II) described in [1] above is formed on a film and then heat-treated to make the optical axis substantially parallel to the film normal direction. And then irradiating with light or radiation, the method for producing an oriented liquid crystal oligomer polymer film according to [1].

[3] An oriented liquid crystal oligomer polymer film obtained by laminating the oriented liquid crystal oligomer polymer film according to the above [1] and a transparent or semitransparent substrate having a hydrophilic surface, and a hydrophilic group. Laminate with wood.

[4] The substrate having a hydrophilic surface is glass,
Characterized by being selected from a hydrophilic polymer film, a laminated film of a hydrophilic polymer and a transparent or translucent polymer film, and a laminated film of a hydrophilic inorganic compound and a transparent or translucent polymer film A laminate of the oriented liquid crystal oligomer polymer film as described in [3] and a substrate.

[5] An oriented liquid crystal oligomer polymer film and a polymer in which the transparent or semitransparent polymer substrate surface is hard-coated and the oriented liquid crystal oligomer polymer film according to [1] are laminated. Laminate with substrate.

[6] A uniaxially oriented retardation film made of a thermoplastic polymer in which a substrate having a hydrophilic surface has an optical axis in the film plane and has positive refractive index anisotropy. And the refractive index of the laminate of the oriented liquid crystal oligomer polymer film and the substrate is represented by the following formula (1) n _X > n _Z > n _Y
(1) (where n _X and n _Y represent the maximum and minimum values of the in-plane refractive index of the laminate, and n _Z represents the refractive index in the thickness direction of the laminate). A laminate of the oriented liquid crystal oligomer polymer film according to [3] and a hydrophilic substrate.

[7] The polymer substrate includes a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the plane of the film and having positive refractive index anisotropy. The refractive index of the laminate of the polymer film and the substrate is represented by the following formula (1) n _X > n _Z > n _Y (1) (where n _X and n _Y are the in-plane refractive index of the laminate, respectively). The maximum value and the minimum value are represented, and n _Z represents the refractive index in the thickness direction of the laminated body.) [5] A laminated body of an oriented liquid crystal oligomer polymer film and a polymer substrate.

[8] A uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the film plane and having positive refractive index anisotropy, and [3] or [4] A composite retardation plate comprising a laminate of an oriented liquid crystal oligomer polymer film and a hydrophilic substrate, wherein the composite retardation plate has a refractive index represented by the following formula (1) n _x > n _Z > n _Y. (1) (where n _x and n _Y represent the maximum and minimum values of the in-plane refractive index of the composite retardation plate, respectively, and n _Z represents the refractive index in the thickness direction of the composite retardation plate). A composite retardation plate characterized by satisfying.

[9] A uniaxially oriented retardation film having a optic axis in the film plane and having a positive refractive index anisotropy and made of a thermoplastic polymer; and the oriented liquid crystal oligomer polymer film according to [5]. A composite retardation plate obtained by laminating a laminate with a polymer substrate, wherein the composite retardation plate has a refractive index represented by the following formula (1) n _x > n _Z > n _Y (1) (where n _x , N _Y respectively represent the maximum and minimum values of the in-plane refractive index of the composite retardation plate, and n _Z represents the refractive index in the thickness direction of the composite retardation plate.). Phase difference plate.

[10] sandwiched between substrates having electrodes,
Between the liquid crystal cell, which has a positive dielectric anisotropy and has a liquid crystal layer that is twisted and aligned substantially horizontally when no voltage is applied and the spiral axis is twisted in the direction perpendicular to the substrate, and the polarizing film that is arranged outside the liquid crystal cell. , The oriented liquid crystal oligomer polymer film according to [1] or the laminate of the oriented liquid crystal oligomer polymer film according to [3] or [4] and a hydrophilic substrate, or [5]
A liquid crystal display device comprising at least one selected from the above-mentioned laminated body of an oriented liquid crystal oligomer polymer film and a polymer substrate. [11] A liquid crystal cell sandwiched between substrates having electrodes, which has a positive dielectric anisotropy, and is composed of a liquid crystal layer that is twisted and aligned substantially horizontally when a voltage is not applied and the helical axis is twisted in a direction perpendicular to the substrate. Between the polarizing film placed on the outside,
[6] A laminated body of the oriented liquid crystal oligomer polymer film and a hydrophilic substrate, or [7] A laminated body of the oriented liquid crystal oligomer polymer film and a polymer substrate, or [8].
Or

[9] A liquid crystal display device comprising at least one selected from the composite retardation plate described in the above.

[12] The liquid crystal display device according to [11], wherein the oriented liquid crystal oligomer polymer film is provided between the retardation film and the polarizing film. Display device. [13] Between a liquid crystal cell sandwiched between electrodes having a positive dielectric constant anisotropy and composed of a liquid crystal layer aligned substantially horizontally when no voltage is applied, and a polarizing film arranged outside thereof In addition, the oriented liquid crystal oligomer polymer film according to [1], a laminate of the oriented liquid crystal oligomer polymer film according to [3] or [4] and a hydrophilic substrate, or the oriented liquid crystal oligomer polymer film according to [5]. And at least one selected from a laminate of a polymer substrate.

Next, the present invention will be described in detail. The liquid crystal oligomer comprising the repeating units (I) and (II) used in the present invention is a side chain type liquid crystal oligomer having a positive refractive index anisotropy in a liquid crystal state and having a nematic phase or a smectic phase. The side chain type liquid crystal oligomer has a skeletal chain of poly-1
Examples thereof include alkyl acrylates and polysiloxanes, and linear or cyclic ones can be used, but a cyclic structure is preferable from the viewpoint of chemical stability of the liquid crystal oligomer. The poly-1-alkyl acrylic acid ester is preferably a polymethacrylic acid ester or a polyacrylic acid ester, more preferably a polymethacrylic acid ester. Among these, polysiloxane side chain type liquid crystal oligomers are preferable. As the group that imparts liquid crystallinity (hereinafter sometimes referred to as mesogen group), a group bonded to the main chain via a bent chain (hereinafter sometimes referred to as spacer) can be generally used.

The side chain type liquid crystal oligomer is not particularly limited in the upper limit temperature at which it exhibits a liquid crystal state, but it is a transition temperature from a liquid crystal phase to an isotropic phase (due to drying or alignment treatment at the time of lamination with a substrate). Hereinafter, it may be referred to as a liquid crystal phase / isotropic phase transition temperature.), So that the transition temperature is 200 ° C. or less, preferably 170.
It is preferable to select the length of the spacer, the kind of the mesogenic group, and the degree of polymerization so that the temperature becomes not higher than 0 ° C, more preferably not higher than 150 ° C. The transition temperature between the liquid crystal phase and the crystal phase or glass phase of these liquid crystal oligomers is not particularly limited, and the transition temperature below room temperature can be used.

The side chain type liquid crystal oligomer used in the present invention is
It is necessary to orient to have anisotropy in refractive index, but the number of repeating units is important as a factor that determines the ease of operation. When the number of repeating units is large, the viscosity is high, and the liquid crystal transition temperature is high, so that high temperature and long time are required for the alignment, and when the number of repeating units is small, the alignment is relaxed at room temperature, which is not preferable. The numbers of repeating units, n and n ', are each independently an integer from 1 to 20 and are selected such that the sum of n and n'is 4 to 21. From the viewpoint of alignment of the liquid crystal oligomer and fixing of alignment after polymerization, the ratio of n and n ′ is in the range of 1: 5 to 5: 1, and more preferably 1: 3 to 3: 1. n and n '
The ratio of can be controlled when synthesizing these liquid crystal oligomers as described later.

The side chain type liquid crystal oligomer has a main chain and a mesogenic group.
The liquid crystal transition temperature and orientation are also dependent on the spacer that connects
To be affected. With a short spacer, the orientation of the mesogenic groups is
Poor and mesogenic group orientation with long spacers
Since relaxation afterwards is likely to occur, as a spacer,
Alkylene group or alkylene having 2 to 10 carbon atoms
An oxy group is preferred. Especially from the viewpoint of high orientation, it has 2 carbon atoms.
To alkylene groups or alkyleneoxy groups
preferable. In addition, due to the ease of synthesis, alkyleneoxy
More preferred are groups. Specifically, as a preferable group,-(C
H₂)₂ -,-(CH₂)₃-,-(CH₂)_Four-,-
(CH₂)_Five-,-(CH₂)₆-,-(CH₂)₃−
O-,-(CH₂)_Four-O-,-(CH₂)_Five-O-,
-(CH ₂)₆-O- is exemplified.

In the oriented liquid crystal oligomer polymer film of the present invention, it is industrially advantageous that the refractive index anisotropy is large. For this purpose, the mesogen group is preferably a group having a large refractive index anisotropy. Examples of the structure giving such a mesogenic group include A in the repeating unit (I) or (II).
r ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each independently 1,
Examples thereof include 4-phenylene group, 1,4-cyclohexane group, pyridine-2,5-diyl group and pyrimidine-2,5-diyl group. Further, the divalent group L bonding Ar ₁ and Ar ₂ or Ar ₃ and Ar ₄ is —CH ₂ —O.
_{-, - O-CH 2 -} , - COO -, - OCO -, - CH
_{2 -CH 2 -, - CH =} N -, - N = CH- or

[0024]

[Chemical 11] Or a group in which Ar ₁ and Ar ₂ are directly bonded or a group in which Ar ₃ and Ar ₄ are directly bonded. More preferably, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each independently a 1,4-phenylene group, pyridine-2,
5-diyl group, pyrimidine-2,5-diyl group,
More preferably, it is a 1,4-phenylene group. Further, the bonding groups L and L ′ are independently -CH ₂ -CH ₂ -,-.
A COO- group and a -OCO- group are preferable, and a -COO- group is more preferable.

The R group in the repeating unit (I) affects the dielectric anisotropy and orientation of the mesogenic group, and from the viewpoint of obtaining a liquid crystal oligomer film having a high refractive index anisotropy,
A halogen, a cyano group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms is selected. A cyano group, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms is preferable, and a cyano group is more preferable.

The terminal group in the repeating unit (II) is a group that fixes the orientation of the liquid crystal oligomer by polymerization. The polymerization group is -OCO-C (R ') = CH 2 (R' represents hydrogen or an alkyl group having 1 to 5 carbon atoms), acrylate groups, methacrylate groups. The method of polymerizing these groups is not particularly limited, but photopolymerization or thermal polymerization with a radical initiator is exemplified, and photopolymerization is preferable from the viewpoint of ease of operation and efficiency of fixing orientation. Known photopolymerization initiators can be used.

The non-polymerizable mesogen group used in the linear or cyclic liquid crystal oligomer having the repeating unit represented by the repeating unit (I) is shown below.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

Among these mesogen groups, numbers 1 to 6, 31 to 36, 61 to 66, 181 to cyano groups having a cyano group are included.
The groups 186 and 211 to 216 are preferable, and the numbers 31 to 36 are more preferable. It is preferable that these mesogen groups are bonded to a polysiloxane-based main chain because they exhibit high orientation, and more preferably those bonded to a cyclic siloxane.

The polymerizable mesogen group used in the linear or cyclic liquid crystal oligomer having the repeating unit (II) is exemplified below.

[0034]

[Table 5]

[0035]

[Table 6]

[0036]

[Table 7]

Among these polymerizable mesogenic groups, numbers 247 to 252 and 259 to 2 having a methacrylate group.
64, 271-276, 319-324, 331-33
The group of 6 is preferable, and more preferably the numbers 259 to 264.
It is the basis of It is preferable that these mesogen groups are bonded to a linear or cyclic polysiloxane-based main chain because they exhibit good characteristics, and it is more preferable that they are bonded to a cyclic polysiloxane.

[0038] These liquid crystal as a synthesis method of the oligomer Sho 63 - 47759 and JP 2-14954
The method described in Japanese Patent No. 4 can be adopted. Examples thereof include a method of adding a mesogenic group of the side chain to a polysiloxane chain and a method of polymerizing an acrylic acid ester or a methacrylic acid ester having a mesogenic group via a flexible spacer group. When a mesogenic group is added to the polysiloxane chain, it has the same structure as the mesogenic group of the side chain of the repeating unit (I) or (II), and an unsaturated double double bond is formed at the terminal which forms an alkyleneoxy group as a spacer. It can be obtained by reacting a reaction raw material having a ω-alkenyloxy group having a bond with polysiloxane under a platinum catalyst. During this reaction,
The bonding ratio of two kinds of mesogenic groups can be controlled by the charging ratio of the reaction raw materials corresponding to the non-polymerizable mesogenic group and the polymerizable mesogenic group. Similarly, in the case where the main chain is an acrylic ester type or an α-alkyl-acrylic acid type, when the two kinds of monomers having the corresponding mesogenic groups are copolymerized, the charging ratio of the monomers is controlled so that a polymerizable mesogenic group is formed. The proportion of non-polymerizable mesogenic groups can be controlled.

The liquid crystal oligomer thus obtained preferably has a nematic phase or a smectic phase. Further, those exhibiting a smectic phase exhibit more excellent optical anisotropy and are therefore more preferred.

The liquid crystal oligomer polymer film having an optical axis substantially parallel to the film normal direction of the present invention is prepared by forming a liquid crystal oligomer polymer film on a hydrophilic base material or a hard-coated polymer substrate. Is formed and an orientation process is performed. The orientation treatment is performed by heat-treating the liquid crystal oligomer polymer film, and the transition from the liquid crystal phase to the isotropic phase at a transition temperature from the crystal phase or the glass phase to the liquid crystal phase (hereinafter sometimes referred to as Tg). The temperature (hereinafter sometimes referred to as Ti) or less is adopted.
Further, the heat treatment temperature (hereinafter sometimes referred to as Tt).
Is preferably Tg + 30 ° C. ≦ Tt <Ti, Tg
It is more preferable to perform heat treatment within the range of + 40 ° C. ≦ Tt <Ti. The heat treatment time is not particularly limited, but if it is too short, the vertical alignment property is not sufficient, and if it is too long, it is not industrially preferable. Therefore, 0.2 minutes or more and 20 hours or less are preferable,
It is more preferably 1 minute or more and 1 hour or less. By the above heat treatment, the mesogenic groups of the liquid crystal oligomer are oriented in a direction substantially perpendicular to the film surface, and have an optical axis in the direction normal to the film surface.

The method for producing the liquid crystal oligomer polymer film is not limited, but a method of applying the liquid crystal oligomer in a solution state and a method of applying it in an isotropic phase state are exemplified, and the method of applying from the solution state is preferable. . Examples of the coating method include a usual roll coating method, a gravure coating method, a bar coating method, a spin coating method, a spray coating method, a printing method, and a depping method. The obtained liquid crystal oligomer polymer film can be used as it is, but it is preferable to use it by laminating it on a substrate.

The thickness of the liquid crystal oligomer polymer film is preferably 0.1 to 20 μm, more preferably 0.5 to 10 μm, and further preferably 1 to 7 μm.
Is. When the thickness is less than 0.1 μm, the expression of optical properties becomes small, and when it exceeds 20 μm, the orientation is difficult, which is not preferable.

The liquid crystal oligomer polymer film is subjected to orientation treatment so that it has an optical axis substantially parallel to the normal line to the film surface, and then the liquid crystal oligomer is polymerized. Specifically, a method of irradiating light, irradiating radiation such as γ-ray, or heating is exemplified. A known polymerization initiator can be used when irradiating with light or heating. Among these methods, the method of irradiating with light and the method of heating are preferable from the viewpoint of easiness of steps, and the method of irradiating light is more preferable from the viewpoint of good retention of orientation.

As the substrate having a hydrophilic surface, a glass plate alone or a glass plate surface used in a liquid crystal cell can be used, and a hydrophilic material containing a hydroxyl group, a carboxylate ion group or a sulfonate ion group can be used. Polymers and hydrophilic inorganic compounds can also be used. Further, a hydrophilic polymer layer or a polymer substrate having a hydrophilic inorganic compound on the surface can also be used.

As the polymer having a hydroxyl group among the hydrophilic polymers, a polymer selected from polyvinyl alcohol, polyethylene vinyl alcohol copolymer, pullulan obtained from starch syrup by microbial fermentation, natural polysaccharides such as dextrin, etc. It is illustrated. Polyvinyl alcohol is preferable from the viewpoint of solubility and ease of giving vertical alignment. Examples of the polymer having a carboxylate ion include polyacrylic acid, sodium polyacrylate, polymethacrylic acid, sodium polyalginate, polycarboxymethyl cellulose soda salt and the like, and sodium polyalginate, polycarboxymethyl cellulose soda salt, polyacrylic Acids are preferred. Moreover, polystyrene sulfonic acid is illustrated as a polymer containing a sulfonate ion. Among these hydrophilic polymers, polyvinyl alcohol, sodium polyalginate, polycarboxymethyl cellulose sodium salt, polyacrylic acid, pullulan and polystyrene sulfonic acid are preferable, and polyvinyl alcohol and sodium polyalginate are more preferable.

Examples of hydrophilic inorganic compounds include transparent inorganic compounds such as Si, Al, Mg and Zr, and fluorides, and ceramics. As a method for forming these inorganic compounds on a polymer film, a method of applying to a polymer film from a state of being dispersed in a solvent or a method of vapor-depositing from a solid state by a known method such as sputtering or electron beam vapor deposition in vacuum is available. It is illustrated. As the inorganic compound used for coating the substrate, a sol-like colloidal dispersion obtained by hydrolyzing silicon tetrachloride or organic aluminum in an organic solvent can be used.

In the laminate of the liquid crystal oligomer polymer film of the present invention and the hydrophilic base material, the hydrophilic base material is effective for orienting the optical axis of the liquid crystal oligomer polymer film substantially parallel to the normal direction. It is a thing. However, since the rubbing-treated polyvinyl alcohol acts as a horizontal alignment film as described above, the rubbing treatment in the hydrophilic polymer layer adversely affects the alignment of the optical axis, which is not preferable.

Polycarbonate, polysulfone, polyarylate, polyethersulfone, 2 cellulose acetate, 3 as a transparent or semitransparent polymer film for coating or vapor-depositing the hydrophilic polymer or hydrophilic inorganic compound used in the present invention. Cellulose acetate, polystyrene, ethylene vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, etc. are exemplified, and preferably polycarbonate, polysulfone, cellulose triacetate, polyethylene terephthalate, polystyrene.

In the laminate of the liquid crystal oligomer polymer film of the present invention and the hydrophilic substrate, heat treatment conditions similar to those of the liquid crystal oligomer polymer film are used in order to make the optical axis of the laminate substantially parallel to the normal direction of the film. Then, the laminate of the liquid crystal oligomer polymer film and the hydrophilic substrate is heat-treated. At that time, a polymer that does not cause changes in optical properties or shape in the temperature range is preferable, and a thermoplastic engineering polymer having a high glass transition temperature or a polymer having a plasticizer added has a high flowing temperature. Is mentioned.
The glass transition temperature of the polymer is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. Cellulose triacetate, polycarbonate, polysulfone, polyether sulfone and polyethylene terephthalate are preferable as the polymer satisfying this condition, and cellulose triacetate, polycarbonate, polysulfone and polyether sulfone are more preferable. Then, polymerization is carried out in the same manner as the liquid crystal oligomer polymer film to fix the orientation.

In the case of the laminate of the oriented liquid crystal oligomer polymer film and the hard-coated polymer substrate which is another embodiment of the present invention, the polymer substrate is polycarbonate, polysulfone, polyarylate, polyether sulfone, 2 Cellulose acetate, cellulose triacetate, polystyrene, ethylene vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate and the like are exemplified, and polycarbonate, polysulfone, polyethylene terephthalate and polystyrene are preferable. Specific treatments include applying a hard coat agent to the surface of these polymer substrates to form a hard coat layer.

Known methods and methods can be used for forming the hard coat agent and the hard coat layer used in the present invention.
There is no particular limitation, but the thickness of the hard coat layer is 0.2 μm.
It is preferably not less than the above, and more preferably not less than 1 μm. As a hard coating agent, known polyurethane type, acrylic oligomer type, acrylic-silicon type,
Examples are those described in the Technical Guide to Plastic Coating Technology for Organopolysiloxane-based and Inorganic Compounds [Published by Industrial Technology Service Center Co., Ltd., pages 183 to 191]. Among these, a photo-curable resin type hard coating agent such as an acrylic oligomer type or an organopolysiloxane type hard coating agent is preferable from the viewpoint of film forming property.

When a liquid crystal oligomer layer is formed on a hard coat-treated polymer substrate, the hard coat layer is subjected to plasma treatment, corona treatment, ultraviolet irradiation, and saponification treatment from the viewpoint of improving the uniformity of the film formation. A treatment for increasing the surface tension of these polymer films may be performed by a known surface modification technique such as.

Next, regarding the method for producing a laminate of the liquid crystal oligomer polymer film and the polymer of the present invention, a substrate having a hydrophilic polymer coated on the surface of the polymer film and a polymer substrate having a hard coat are exemplified. To explain. First, using a transparent or translucent polymer film such as polycarbonate, polysulfone, polyarylate, polyethersulfone, cellulose diacetate, cellulose triacetate, polyethylene terephthalate, polyethylene naphthalate as a substrate, Of a hydrophilic polymer or a hydrophilic inorganic compound is formed on the surface.

The method for forming the hydrophilic polymer is not particularly limited. For example, the hydrophilic polymer is dissolved in a solvent in which the hydrophilic polymer can be dissolved and the substrate is not dissolved or swollen, and then the roll coating method is used. , Gravure coating method, bar coating method, spin coating method, spray coating method, printing method,
Examples thereof include a method of applying a known method such as a depping method, and a method of melting the polymer and then applying a known method such as a roll coating method, a gravure coating method, a bar coating method, a spray coating method, and a depping method. It From the viewpoint of easy production among these film forming methods, a roll coating method, a gravure coating method, a bar coating method from a polymer solution,
It is preferable to form a film by a spin coating method, a spray coating method, a depping method or the like.

Here, polycarbonate, polysulfone,
Polymer films such as polyarylate and polyethersulfone have low surface tension and hydrophilic polymer solutions may be repelled.Therefore, use known surface modification techniques such as plasma treatment, corona treatment, ultraviolet irradiation, and saponification treatment. The hydrophilic polymer may be deposited after increasing the surface tension of these polymer films. The method for forming a hydrophilic inorganic compound is not particularly limited, and for example, after the inorganic compound is dispersed in a solvent that forms a stable colloidal dispersion system and does not dissolve or swell the base material, then roll it. A coating method, a gravure coating method, a bar coating method, a spin coating method, a spray coating method, a printing method, a coating method by a known method such as a depping method, or a sputtering method of the inorganic compound in a vacuum, an electron beam heating method, A method of vapor deposition by a known vacuum vapor deposition method such as a resistance heating method is exemplified.

When a hard-coated polymer substrate is used, first, a transparent or translucent polymer substrate such as polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, polystyrene, ethylene vinyl alcohol copolymer is used. A hard coat agent is formed on the surface of the polymer film by using a polymer film such as coalesced polyethylene terephthalate or polyethylene naphthalate as a substrate. As a film forming method of the hard coating agent, a roll coating method from a state of being dissolved or dispersed in a solvent, a dipping method, a gravure coating method,
Examples include known coating methods such as bar coating method, spin coating method, spray coating method, printing method, and film forming methods such as sputtering method in vacuum, electron beam heating vapor deposition method, and known vapor deposition method such as resistance heating method. After the film is formed by these film forming methods, it is cured by irradiation with ultraviolet rays or heat treatment depending on the type of the hard coating agent used. When forming a film by a vapor deposition method, attention must be paid to the vapor deposition direction, and oblique vapor deposition is not preferable because it adversely affects the orientation of the optical axis of the oriented liquid crystal oligomer.

The thickness of the transparent or translucent polymer film used is not particularly limited, but is preferably 1 μm or more and 500 μm or less, more preferably 10 μm or more and 300 μm or less, and further preferably 40 μm or more and 200 μm or less.

The thickness of the obtained hydrophilic polymer or inorganic compound is not particularly limited, but is 0.1 μm or more and 500 or more.
μm or less, preferably 0.5 μm or more and 100 μm
The thickness is more preferably 1 μm or more and 50 μm or less. In the case of hydrophilic polymer, the solvent used is not particularly limited as long as it dissolves the hydrophilic polymer, but water is preferably used.

The thickness of the hard coat layer to be obtained is also not particularly limited and is 0.1 μm or more and 500 μm or less, preferably 0.5 μm or more and 100 μm or less, and more preferably 1 μm or more and 50 μm or less.

Then, a liquid crystal oligomer is deposited on the polymer film on which the hydrophilic polymer or inorganic compound is deposited or on the polymer film subjected to the hard coating treatment. The film forming method is not particularly limited, but for example, a film can be formed in the same manner as a liquid crystal oligomer film, and after dissolving the liquid crystal oligomer in a solvent that does not dissolve or swell the base material, the hydrophilic polymer, the inorganic compound or the hard coat film, , A roll coating method, a gravure coating method, a bar coating method, a spin coating method, a spray coating method, a printing method, a depping method, etc., or a liquid crystal oligomer by heating the liquid crystal oligomer to a temperature higher than the solid phase / liquid crystal phase transition temperature. After reducing the viscosity of, a known method such as a roll coating method, a gravure coating method, a bar coating method, a spray coating method, or a depping method is exemplified. From the viewpoint of easy production among these coating methods, the liquid crystal oligomer solution is roll-coated,
It is preferable to form a film by a gravure coating method, a bar coating method, a spin coating method, a spray coating method, a depping method, or the like.

The thickness of the obtained liquid crystal oligomer polymer layer is preferably 0.1 μm or more and 20 μm or less, more preferably 0.5 μm or more and 10 μm or less, and further preferably 1 μm or more and 7 μm or less. When the thickness is less than 0.1 μm, the expression of optical properties becomes small, and when the thickness is more than 20 μm, the orientation is difficult, which is not preferable.

As described above, in order to obtain a high degree of vertical alignment of the liquid crystal oligomer, the liquid crystal oligomer / polymer laminated film is heat-treated in the same manner as in the case of the liquid crystal oligomer polymer film described above at the same temperature and treatment time. However, especially in the case where the glass transition temperature of the base material used or the base material to which the additive is added is above the flow temperature of the base material, there is a problem in the production method such as deformation of the base material, the hydrophilic polymer or the hard coat film. The upper limit temperature is preferably equal to or lower than the glass transition temperature or flow temperature of the substrate. By this treatment, the liquid crystal oligomer film on the polymer substrate is almost vertically aligned. Further, there is no particular limitation on the heating rate and the cooling rate in the heat treatment.

The method for producing the transparent or translucent polymer film of the present invention includes solvent casting, extrusion molding,
A molding method such as a press molding method may be used.

Even when a glass plate or a hydrophilic polymer film is used as the substrate, a laminate of the liquid crystal oligomer polymer and the substrate can be obtained in the same manner.

The oriented liquid crystal oligomer polymer film or the laminate of the liquid crystal oligomer polymer film of the present invention and the hydrophilic substrate or the hard-coated polymer film has a optic axis substantially parallel to the normal direction of the film. By using simultaneously a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis inside and having positive refractive index anisotropy, a composite retardation plate or a composite retardation film can be obtained. it can. Hereinafter, the composite retardation plate or the composite retardation film is generically referred to as a composite retardation plate. Regarding the viewing angle dependence of the retardation of the composite retardation plate, the maximum in-plane refractive index (n _X ) and the minimum refractive index (n _Y ) of the composite retardation plate and the refractive index in the direction perpendicular to the surface of the composite retardation plate ( n
It is known to be related to the size of _Z ). As described in JP-A-3-155522, the anisotropy of the refractive index can be obtained as an arithmetic mean from the refractive index and the film thickness of each material plate or film constituting the composite retardation plate. Indicates retardation, and it is practical to estimate the anisotropy of refractive index from the angle dependence of retardation. When evaluating the anisotropy of the refractive index by the ratio R (θ) / R (0) of the retardation R (0) in the vertical direction to the composite retardation plate and the retardation R (θ) when tilted by θ degrees , 1.10> R (40 °) / R (0)>
In the range of 0.90, it corresponds to n _X > n _Z > n _Y , and shows good viewing angle characteristics.

Examples of the thermoplastic polymer having positive refractive index anisotropy used in the composite retardation plate of the present invention include polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, polyvinyl alcohol, Examples thereof include polyethylene vinyl alcohol copolymer and polyethylene terephthalate. The thermoplastic polymer is uniaxially oriented and used as a retardation film. The liquid crystal oligomer / base material laminate and the uniaxially oriented retardation film may be laminated by adhering them with an adhesive or the like, or may be used separately.

As a method for producing a film (hereinafter sometimes referred to as a raw film) used as a raw material for a retardation film composed of these thermoplastic polymers, there are solvent casting method, extrusion molding method, press molding method and the like. A molding method may be used. Examples of the stretching method for making the original film a uniaxially oriented retardation film having an optical axis in the film plane include a tenter stretching method, a roll stretching method, and a roll compression stretching method. In order to obtain a uniform retardation film, it is preferable to stretch the film formed by the solvent casting method by the tenter stretching method.

In the liquid crystal display device of the present invention, the position where the oriented liquid crystal oligomer polymer film or the laminate of the liquid crystal oligomer polymer film and the substrate is placed is not particularly limited as long as it is between the two polarizing plates of the liquid crystal display. . For example, it is exemplified between the polarizing plate and the liquid crystal cell for display, between the polarizing plate and the protective film of the polarizing plate, between the retardation film and the polarizing plate, between the retardation film and the liquid crystal cell for display. STN type LC
When it is applied to D, it is preferable to dispose it between the retardation film and the polarizing plate because an LCD having a wider viewing angle can be obtained. Further, the laminated composite retardation plate containing the liquid crystal oligomer polymer film may be placed between the polarizing plate and the liquid crystal cell for display, but when applied to the STN type LCD, the liquid crystal oligomer polymer film is polarized. It is preferable to dispose the plate side so that the LCD has a wider viewing angle.

[0069]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The glass transition point of the obtained liquid crystal oligomer and the transition temperature between the liquid crystal phase and the isotropic phase were evaluated by a polarization microscope observation and a differential scanning calorimeter (DSC). The liquid crystal oligomer was scanned at a scanning rate of 10 ° C./min, and the transition temperature was evaluated from the data of the second and subsequent times.
Regarding Tg, the peak of the first derivative of the endothermic curve at the time of temperature rise was regarded as Tg, and for Ti, the endothermic peak which is considered to be due to the liquid crystal phase / isotropic phase transition was regarded as Ti.

The obtained liquid crystal oligomer polymer film /
In order to confirm that the substrate laminate has an optical axis substantially in the direction of the normal to the film, it can be confirmed that when the substrate has no birefringence, the laminate film is almost completely extinguished when placed horizontally under crossed Nicols. It was confirmed by inclining around an arbitrary axis and increasing the retardation as the inclination angle increased. When there is birefringence in the plane, the slow axis is the tilt axis.

The laminated composite retardation film or film of the present invention was evaluated as follows, unless otherwise specified. First, the in-plane birefringence is evaluated. In a polarizing microscope equipped with a tilt stage, the laminated film is arranged horizontally and the retardation (hereinafter R (0) is measured by a Senarmon birefringence measurement method using a Senarmon compensator.
Abbreviated as)). Next, the angle dependence of retardation was evaluated by θ ° with the slow axis in the horizontal plane as the tilt axis.
Retardation (hereinafter R
(Abbreviated as (θ)).

The viewing angle in the examples is R (θ) / R
(0) = 1.10 or R (θ) / R (0) = 0.90
Θ is defined as the viewing angle.

Example 1 1% of polyvinyl alcohol (Poval 117 manufactured by Kuraray Co., Ltd.) was formed on a cellulose acetate film having a thickness of 80 μm.
A 0% aqueous solution was applied and dried in hot air at 100 ° C. The thickness of the obtained polyvinyl alcohol was 3 μm.
4- (allyl-oxy) -benzoic acid-4'-cyanophenyl ester and 4- (allyloxy) -benzoic acid-
The (4′-methacryloyloxy-phenyl) ester was reacted with pentamethylcyclopentasiloxane at a mixing ratio of 1: 1 in the same manner as in the method described in JP-B-63-41400 to obtain a non-polymerizable mesogenic group and a polymerizable compound. A cyclic pentasiloxane liquid crystal oligomer having a mesogenic group was obtained. This liquid crystal oligomer has elemental analysis, infrared absorption spectrum, H-
The structure was confirmed from the NMR spectrum.

The Tg of the obtained liquid crystal oligomer is 1
It was 8.7 degreeC and Ti was 117.5 degreeC. This liquid crystal oligomer was dissolved in methylene chloride to a concentration of 5 wt%, and the product name IRGACURE 9 was used as a photopolymerization initiator.
07 (manufactured by Ciba-Geigy) to the liquid crystal oligomer 2
It mixed so that it might be set to wt%. Gap width of 40μ on the cellulose acetate film coated with polyvinyl alcohol
The liquid crystal oligomer solution was applied using an applicator of m. After coating, it was dried at room temperature. The obtained liquid crystal oligomer / polyvinyl alcohol / 3 cellulose acetate laminated film was heated on a hot plate heated to 95 ° C. for 5 minutes and cooled. Further, the liquid crystal oligomer laminated film was irradiated with a high pressure mercury lamp to obtain an integrated light amount of 500 mJ / cm ² of ultraviolet rays.

The obtained liquid crystal oligomer polymer / polymer laminate film was quenched under crossed Nicols, and the retardation was thought to be due to cellulose triacetate 5.3 nm.
However, when the laminated film was tilted from the horizontal plane, the retardation increased. The relationship between the tilted angle and the retardation at that time is shown in FIG. Since the larger the tilt angle, the larger the retardation, it was found that the liquid crystal oligomer polymer layer was vertically aligned. At this time, the thickness of the liquid crystal oligomer polymer layer was measured by a needle-contact type film thickness meter (Alpha Step AS-200 manufactured by Tencor Co., Ltd.) and found to be 2.3 μm.

Next, as a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the film plane and having a positive refractive index anisotropy, a retardation film made of polycarbonate (trade name: Sumika Light (SEF-40
0426) Sumitomo Chemical Co., Ltd., R (0) = 380n
m, viewing angle 39 °).

When the polycarbonate retardation film and the liquid crystal oligomer polymer / polymer laminated film were laminated, the viewing angle was 60 ° or more, and the composite retardation having a wider viewing angle than that of the polycarbonate retardation film alone. A film was obtained. Further, when one composite retardation film is provided between the upper and lower polarizing plates and the liquid crystal cell of the STN type liquid crystal display device, a black and white display is obtained and a good viewing angle characteristic is exhibited.

Comparative Example 1 A laminated film of a polymer of a liquid crystal oligomer and a polymer was obtained in the same manner as in Example 1 except that the heat treatment was not performed after the liquid crystal oligomer was applied. The obtained laminated film was cloudy. Observation of the laminated film obtained under crossed Nicols revealed that it was cloudy and that the liquid crystal oligomer polymer was not vertically aligned.

Example 2 A laminated film of a liquid crystal oligomer polymer film and a polymer was obtained in the same manner as in Example 1 except that polyvinyl alcohol of Example 1 was changed to sodium alginate. The obtained laminated film of the liquid crystal oligomer polymer and the polymer was transparent under crossed nicols and had a retardation of 3 nm, but when the laminated film was tilted from the horizontal plane, retardation appeared. Retardation when tilted to 50 ° is 1
It was 05 nm. It was confirmed that the liquid crystal oligomer polymer layer was vertically aligned because the retardation increased as it was tilted. The thickness of the liquid crystal oligomer polymer layer was measured and found to be 2.1 μm.

When the polycarbonate retardation film used in Example 1 and the liquid crystal oligomer polymer / polymer laminated film were laminated, the viewing angle was 60 ° or more, which was wider than that of the polycarbonate retardation film alone. A corner composite retardation film was obtained.

Further, this composite retardation film was treated with STN.
When one sheet is arranged between each of the upper and lower polarizing plates and the liquid crystal cell of the type liquid crystal display device, a black and white display is obtained, and good viewing angle characteristics are exhibited.

Example 3 Cellulose triacetate of Example 1 was converted into R (0) described in Example 1.
A laminated film of a liquid crystal oligomer polymer film and a polymer was obtained in the same manner as in Example 1 except that a polycarbonate retardation film of 380 nm (viewing angle 39 °) was used. The retardation of the obtained laminated film of the liquid crystal oligomer polymer and the polymer was 382 nm. This was almost the same as the retardation of the polycarbonate retardation film alone. Even if the laminated film was tilted from the horizontal plane, the retardation hardly changed, the viewing angle was 60 ° or more, and the viewing angle was greatly improved as compared with the case of using the retardation film alone.

Further, this composite retardation film was treated with STN.
When one sheet is arranged between the upper and lower polarizing plates and the liquid crystal cell of the type liquid crystal display device, a black and white display is obtained, and good viewing angle characteristics are exhibited.

Example 4 A laminated film of a liquid crystal oligomer polymer film and a polymer was obtained in the same manner as in Example 1 except that cellulose triacetate of Example 1 was used as an unstretched polysulfone film. The retardation of the obtained laminated film of the liquid crystal oligomer polymer and the polymer was 3 nm. This was almost the same retardation value as that of the unstretched polysulfone film alone. When this laminated film was tilted from the horizontal plane, large retardation appeared. The retardation when tilted at 60 ° was 64 nm. It was confirmed that the liquid crystal oligomer polymer layer was vertically aligned because the retardation increased as it was tilted. The thickness of the liquid crystal oligomer polymer layer was measured and found to be 2.4 μm.

When the polycarbonate retardation film used in Example 1 and the laminated film of the liquid crystal oligomer polymer and the polymer were laminated, the viewing angle was 60 ° or more.
A composite retardation film having a wider viewing angle was obtained as compared with the case of using the polycarbonate retardation film alone.

Further, this composite retardation film was treated with STN.
When one sheet is arranged between the upper and lower polarizing plates and the liquid crystal cell of the type liquid crystal display device, a black and white display is obtained, and good viewing angle characteristics are exhibited.

Example 5 A laminated film of a liquid crystal oligomer polymer film and glass was obtained in the same manner as in Example 1 except that the cellulose triacetate of Example 1 was used as a glass plate and polyvinyl alcohol was not used. The obtained laminated film of the liquid crystal oligomer polymer film and glass was transparent under crossed nicols and had a retardation of 0 nm, but when the laminated film was tilted from the horizontal plane, retardation appeared. The retardation when tilted at 50 ° was 99 nm. It was confirmed that the liquid crystal oligomer polymer layer was vertically aligned because the retardation increased as it was tilted. When the thickness of the liquid crystal oligomer polymer layer was measured, it was 2.0 μm.
Met. When a laminated film of a liquid crystal oligomer polymer film and glass and the same retardation film made of polycarbonate as described in Example 1 were laminated, the viewing angle was 60 ° or more, and the viewing angle was wider than that of the polycarbonate retardation film alone. A corner composite retardation film was obtained.

Further, this composite retardation film was treated with STN.
When one sheet is arranged between the upper and lower polarizing plates and the liquid crystal cell of the type liquid crystal display device, a black and white display is obtained, and good viewing angle characteristics are exhibited.

Example 6 On the polycarbonate retardation film described in Example 1, #
Using a bar coater No. 9, silicon tetrachloride partially hydrolyzed into a stable colloid was applied and air dried. The liquid crystal oligomer described in Example 1 was dissolved in toluene to a concentration of 20%, and IRGACURE 9 was used as a photopolymerization initiator.
07 (manufactured by Ciba-Geigy) to the liquid crystal oligomer 2
It melt | dissolved so that it might become%. When this solution was applied onto the above-mentioned substrate with a # 9 bar coater and dried at room temperature, 2.
A 5 μm liquid crystal oligomer film was obtained. The obtained liquid crystal oligomer film was cloudy. The obtained laminated film of the oriented liquid crystal oligomer and the substrate was heat-treated at 80 ° C. for 5 minutes and irradiated with ultraviolet rays from a high pressure mercury lamp at ² J / cm ² .

The obtained laminate of the oriented liquid crystal oligomer polymer and the substrate showed 380 nm due to the retardation film. When this laminated film was not tilted, it was tilted with the slow axis of the retardation film as the tilt axis, but there was almost no change in retardation, and the viewing angle was 60 ° or more. Is greatly improved.

Further, if one laminate film of the oriented liquid crystal oligomer polymer and the substrate is arranged between the upper and lower polarizing plates of the STN type liquid crystal display device and the liquid crystal cell, a black and white display is obtained and a good viewing angle is obtained. Show the characteristics.

Example 7 On the polycarbonate retardation film described in Example 1, #
A hard coat agent (trade name: Sumiflex XR-11, manufactured by Sumitomo Chemical Co., Ltd.) was formed into a film having a thickness of about 5 μm using a bar coater No. 9 and photocured. The film was plasma treated in Ar gas. The liquid crystal oligomer described in Example 1 was dissolved in toluene to a concentration of 20%, and IRGACURE 907 (manufactured by Ciba Geigy) was used as a photopolymerization initiator.
Was dissolved in the liquid crystal oligomer to a concentration of 2%.
When this solution was applied onto the above-mentioned substrate with a # 9 bar coater and dried at room temperature, a liquid crystal oligomer film of 2.1 μm was obtained. The obtained liquid crystal oligomer film was cloudy. The obtained laminate film of the oriented liquid crystal oligomer and the substrate was heat-treated at 80 ° C. for 5 minutes and irradiated with ultraviolet rays from a high pressure mercury lamp at 1 J / cm ² .

The obtained laminate of the oriented liquid crystal oligomer polymer and the substrate showed 380 nm due to the retardation film. When this laminated film was not tilted, it was tilted with the slow axis of the retardation film as the tilt axis, but there was almost no change in retardation, and the viewing angle was 60 ° or more. Is greatly improved.

Further, when one laminate film of the oriented liquid crystal oligomer polymer and the substrate is arranged between the upper and lower polarizing plates of the STN type liquid crystal display device and the liquid crystal cell, a black and white display is obtained and a good viewing angle is obtained. Show the characteristics.

Example 8 On the polycarbonate retardation film described in Example 1, #
Using a bar coater No. 9, a UV-curable acrylic hard coat agent was applied to a thickness of 5 μm, air-dried, and then UV-irradiated at 3 J / cm ² , and the hardened hard coat layer was subjected to corona treatment. The liquid crystal oligomer described in Example 1 was dissolved in toluene to a concentration of 20%, and Irgacure 907 (manufactured by Ciba Geigy) as a photopolymerization initiator was dissolved in a concentration of 2% with respect to the liquid crystal oligomer. This solution was applied onto the above-mentioned substrate with a # 8 bar coater and dried at room temperature to obtain a 3 μm liquid crystal oligomer film. The obtained liquid crystal oligomer film was cloudy. The obtained composite retardation film was heat-treated at 80 ° C. for 5 minutes and irradiated with ultraviolet rays from a high pressure mercury lamp at 1 J / cm ² .

The obtained composite retardation film showed 380 nm due to the retardation film. This laminated film was tilted with the slow axis of the retardation film when not tilted as the tilt axis, but there was almost no change in retardation,
The viewing angle was 60 ° or more, and the viewing angle was greatly improved as compared with the case of using the retardation film alone.

Further, when one composite retardation film is arranged between the upper and lower polarizing plates and the liquid crystal cell of the STN type liquid crystal display device, a black and white display is obtained and a good viewing angle characteristic is exhibited.

Example 9 A cellulose triacetate film (Fujitac SH-80, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm, which was surface-saponified, was used as an optically transparent and isotropic polymer substrate. A 30% toluene solution of the liquid crystal oligomer obtained in Example 1 was formed into a film by a gravure coating method so that the film thickness after drying was 2.8 μm, and heat treatment was performed at 80 ° C. for 2 minutes to vertically align the film. 500mJ as light quantity
/ Cm ² of ultraviolet rays was irradiated to obtain a liquid crystal oligomer polymer / polymer laminated film having an isotropic refractive index in the film plane and an in-plane refractive index smaller than the refractive index in the thickness direction. .

Further, as a uniaxially oriented retardation film,
Uniaxially oriented retardation film having an in-plane retardation of 428 nm (trade name: Sumikalite (SEF-360
428) Sumitomo Chemical Co., Ltd.] was used. A retardation film obtained by laminating a liquid crystal oligomer polymer / polymer laminate film and a uniaxially oriented retardation film with an adhesive (constitution: 3
Two sheets of cellulose acetate film / polymer liquid crystal layer / polycarbonate uniaxially oriented film) were obtained.

Word processor (brand name OASYS
30LX-401 FUJITSU LIMITED's FTN LCD mounted above and below the retardation film between the polarizing film and the liquid crystal cell so that the polycarbonate uniaxially oriented film is on the liquid crystal cell side. Laminated. This FTN LCD has a small change in contrast depending on the viewing angle.
Wide viewing angle characteristics were exhibited in the directions of °, 240 ° and 300 °. FIG. 2 shows isocontrast curves with contrast ratios (hereinafter sometimes referred to as CR) of 1, 5, 10, and 15.

The isocontrast curve was measured by a transmission method using LCD-7000 manufactured by Otsuka Electronics Co., Ltd. Further, the voltage applied to the liquid crystal display device was set to a state in which the contrast was the best when viewed from the front of the liquid crystal display device by visual observation in the actual driving state of the liquid crystal display device. In addition, the retardation of the uniaxially oriented retardation film in this example was measured by using a spectroscope (MCPD-1000 manufactured by Otsuka Electronics Co., Ltd.) in which two polarizing prisms are arranged in parallel in the optical system. It was calculated from the maximum wavelength.

Example 10 An FTN LCD was produced in the same manner as in Example 9 except that the thickness of the polymer liquid crystal layer of the liquid crystal oligomer polymer / polymer laminate film was 3.3 μm. This FT
The N-type LCD showed a small change in contrast depending on the viewing angle, and showed good viewing angle characteristics. CR is 1, 5, 1
The isocontrast curves of 0 and 15 are shown in FIG.

[0103]

INDUSTRIAL APPLICABILITY In the present invention, by using an oriented liquid crystal oligomer polymer film whose optical axis is substantially parallel to the normal direction, it is possible to laminate with a transparent or semitransparent polymer film or to obtain a uniaxially oriented film. By combining with a retardation film, a composite retardation plate with a wide viewing angle can be obtained. Further, by applying these to the STN type liquid crystal display device, it is possible to remarkably improve the display characteristics of the liquid crystal display device, particularly the viewing angle characteristics.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a retardation and a tilt angle of a laminated film of a liquid crystal oligomer polymer described in Example 1 and a polymer.

FIG. 2 is a diagram showing isocontrast curves in Example 9.

FIG. 3 is a diagram showing isocontrast curves in Example 10.

Front page continued (72) Inventor Akiko Shimizu 2-10-1 Tsukahara, Takatsuki City, Osaka Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor Makoto Namioka 2-10-1 Tsukahara, Takatsuki City, Osaka Sumitomo Chemical Co., Ltd. In-company (72) Inventor Masato Kuwahara 6 Kitahara, Tsukuba-shi, Ibaraki Sumitomo Chemical Co., Ltd. In-company (56) Reference JP 62-70407 (JP, A) JP 2-113063 (JP, A) Special Kaihei 5-27235 (JP, A) JP-A-3-21904 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 5/30

Claims (13)

(57) [Claims] 1. A film comprising a polymer of a liquid crystal oligomer having a positive refractive index anisotropy and exhibiting a nematic phase or a smectic phase, the liquid crystal oligomer mainly comprising the following repeating units (I) and (II). The unit is selected from linear or cyclic liquid crystal oligomers, and the number of repeating units (I) and (II) in one molecule of the oligomer is n, respectively.
And n ′, n and n ′ are each independently an integer from 1 to 20, and 4 ≦ n + n ′ ≦ 21
Wherein the repeating unit (II) is polymerized, and the optical axis of the film is substantially parallel to the normal direction of the film. [Chemical 1] [Chemical 2] [Wherein A is a group represented by the following formula (III) or (IV), and in formula (III), -Si-O- is represented by formula (I).
Or the main chain of (II), and in the formula (IV), -C
—CH ₂ — is the backbone of formula (I) or (II),
The OO group is located on a side chain that is not R ₁ or R ₂ of the side chain. When A is formula (III) in formula (I) and A is formula (III) in formula (II), R ₁ and R ₂ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms or phenyl. It is a base. In formula (I), when A is formula (IV), and in formula (II), A is formula (I)
In the case of V), R ₁ and R ₂ independently represent hydrogen or 1 to 1 carbon atoms.
6 is an alkyl group. [Chemical 3] [Chemical 4] k and k'independently represent an integer of 2 to 10, m and m'independently represent 0 or 1, and Ar ₁ , Ar ₂ , A
r ₃ and Ar ₄ are independently a 1,4-phenylene group, 1,
4-cyclohexane group, pyridine-2,5-diyl group,
Pyrimidine-2,5-diyl group, L and L '-CH ₂ independently _{-O -, - O-CH 2} -, - COO -, - O
_{CO -, - CH 2 -CH 2} -, - CH = N -, - N = C
H- or Is a divalent group represented by, p and p ′ are independently 0 or 1, R is a halogen, a cyano group, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, R'is hydrogen or an alkyl group having 1 to 5 carbon atoms. ] 2. Repeating units (I) and (I) according to claim 1.
2. A linear or cyclic liquid crystal oligomer comprising I) is formed on a film, heat treated to make the optical axis substantially parallel to the normal direction of the film, and then irradiated with light or radiation. Of the oriented liquid crystal oligomer polymer film described in 1. 3. An oriented liquid crystal oligomer polymer film obtained by laminating the oriented liquid crystal oligomer polymer film according to claim 1 and a transparent or semitransparent substrate having a hydrophilic surface, and a hydrophilic substrate. Stack of. 4. A substrate having a hydrophilic surface is glass, a hydrophilic polymer film, a laminated film of a hydrophilic polymer and a transparent or semitransparent polymer film, and a transparent or semitransparent hydrophilic inorganic compound. 4. A laminated body of the oriented liquid crystal oligomer polymer film according to claim 3 and a hydrophilic substrate, which is selected from a laminated film of the polymer film of 1. 5. An oriented liquid crystal oligomer polymer film obtained by laminating a transparent or translucent polymer substrate surface with a hard coat treatment and the oriented liquid crystal oligomer polymer film according to claim 1, and a polymer substrate. And a laminate. 6. A uniaxially oriented retardation film made of a thermoplastic polymer, wherein the substrate having a hydrophilic surface has an optic axis in the film plane and has positive refractive index anisotropy. The refractive index of the laminate of the oriented liquid crystal oligomer polymer film and the substrate is represented by the following formula (1) n _X > n _Z > n _Y
(1) (where n _X and n _Y represent the maximum and minimum values of the in-plane refractive index of the laminate, and n _Z represents the refractive index in the thickness direction of the laminate). A laminated body of the oriented liquid crystal oligomer polymer film according to claim 3 and a hydrophilic substrate. 7. A polymer substrate comprising a uniaxially oriented retardation film made of a thermoplastic polymer having an optical axis in the plane of the film and having positive refractive index anisotropy, and alignment liquid crystal oligomer polymerization. (1) n _X > n _Z > n _Y (1) where n _X and n _Y are the maximum in-plane refractive index of the laminate. Value, the minimum value, and n _Z represents the refractive index in the thickness direction of the laminate.) The laminate of the oriented liquid crystal oligomer polymer film and the polymer substrate according to claim 5, wherein 8. A uniaxially oriented retardation film comprising a thermoplastic polymer having an optical axis in the film plane and having positive refractive index anisotropy, and the oriented liquid crystal oligomer according to claim 3 or 4. A composite retardation plate obtained by laminating a laminate of a polymer film and a hydrophilic substrate, wherein the composite retardation plate has a refractive index represented by the following formula (1) n _x > n _Z > n _Y (1) (Here, n _x and n _Y represent the maximum and minimum values of the in-plane refractive index of the composite retardation plate, respectively, and n _Z represents the refractive index in the thickness direction of the composite retardation plate.) Characteristic composite retardation plate. 9. A uniaxially oriented retardation film comprising a thermoplastic polymer having an optical axis in the film plane and having positive refractive index anisotropy, and an oriented liquid crystal oligomer polymer according to claim 5. A composite retardation plate obtained by laminating a laminate of a film and a polymer substrate, wherein the composite retardation plate has a refractive index represented by the following formula (1) n _x > n _Z > n _Y (1) (where n _x and n _Y represent the maximum and minimum values of the in-plane refractive index of the composite retardation plate, respectively, and n _Z represents the refractive index in the thickness direction of the composite retardation plate. Composite retarder. 10. A liquid crystal cell comprising a liquid crystal layer sandwiched between substrates having electrodes and having a positive dielectric anisotropy, and which is twisted and aligned substantially horizontally when a voltage is not applied and with a helical axis perpendicular to the substrate. Between the polarizing film and the polarizing film arranged on the outside thereof, or a laminate of the oriented liquid crystal oligomer polymer film according to claim 1 or the oriented liquid crystal oligomer polymer film according to claim 3 or 4 and a hydrophilic substrate, or A liquid crystal display device comprising at least one selected from the laminate of the oriented liquid crystal oligomer polymer film according to claim 5 and a polymer substrate. 11. A liquid crystal cell comprising a liquid crystal layer sandwiched between substrates having electrodes, which has a positive dielectric anisotropy, and which is twisted and aligned substantially horizontally when a voltage is not applied and with a helical axis perpendicular to the substrate. A laminated body of the oriented liquid crystal oligomer polymer film according to claim 6 and a hydrophilic substrate, or the oriented liquid crystal oligomer polymer film according to claim 7 and a polymer between the polarizing film and the polarizing film disposed outside thereof. A liquid crystal display device comprising a laminate with a substrate or at least one selected from the composite retardation plate according to claim 8 or 9. 12. The liquid crystal display device according to claim 11, wherein the oriented liquid crystal oligomer polymer film is provided between the retardation film and the polarizing film. . 13. A liquid crystal cell sandwiched between electrodes having a positive dielectric constant anisotropy, the liquid crystal cell comprising a liquid crystal layer aligned substantially horizontally when no voltage is applied, and a polarizing film arranged outside the liquid crystal cell. In between, the oriented liquid crystal oligomer polymer film according to claim 1, a laminate of the oriented liquid crystal oligomer polymer film according to claim 3 or 4 and a hydrophilic substrate, or the oriented liquid crystal oligomer polymer film according to claim 5. And at least one selected from a laminate of a polymer substrate.