JP2002365635A - Manufacturing method for homeotropically aligned liquid crystal film and homeotropically aligned liquid crystal film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a homeotropically aligned liquid crystal film wherein the homeotropic alignability of a homeotropically aligned liquid crystal layer, formed from the homeotropically aligned liquid crystal layer which is directly formed on a substrate by using a side chain type liquid crystal polymer without using a vertical alignment layer is satisfied regardless of the quality of the material of the substrate. SOLUTION: The manufacturing method for the homeotropically aligned liquid crystal film is characterized in that the side chain type liquid crystal polymer capable of forming the homeotropically aligned liquid crystal layer on the substrate on which the vertical alignment layer is not provided is applied on the substrate on which the vertical alignment layer is not provided via an anchor coating layer and the side chain type liquid crystal polymer is homeotropically aligned in a liquid crystal state and fixated in the state that the alignment state is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a homeotropically aligned liquid crystal film. The present invention also relates to a homeotropically-aligned liquid crystal film obtained by the production method, and further to an optical film. The homeotropic alignment liquid crystal film can be used alone or in combination with other films as an optical film such as a retardation film, a viewing angle compensation film, an optical compensation film, and an elliptically polarizing film. Further, the present invention relates to a liquid crystal display device using the optical film.

[0002]

2. Description of the Related Art Homeotropic alignment of a liquid crystal compound is as follows.
This occurs when the molecular long axis of the liquid crystal phase is substantially perpendicular to the substrate on which the thin film (liquid crystal phase) is formed on average. Very few materials undergo spontaneous homeotropic alignment, and therefore vertical alignment agents are generally used to effect such alignment. As a liquid crystal compound that can be homeotropically aligned by a vertical alignment agent,
For example, a nematic liquid crystal compound is known. For an overview on the alignment technique for such liquid crystal compounds, see, for example, Chemical Review 44 (Surface Modification, edited by The Chemical Society of Japan, 156-16).
3).

Various organic or inorganic aligning agents are known as vertical aligning agents capable of homeotropically aligning the liquid crystal compound, but most of the commonly used aligning agents work effectively on a glass substrate. It is designed to be.

[0004] Such conventional organic alignment agents include:
For example, lecithin, silane-based surfactant, n-octadecyltriethoxysilane, titanate-based surfactant,
Examples include a pyridinium salt-based polymer surfactant, hexadecyltrimethylammonium halide or a chromium complex. These organic aligning agents are dissolved in a suitable volatile solvent so that the active ingredient is in a very small amount (typically less than 1%) and then, for example, by spin coating or other well-known coating methods. After being applied on the substrate, the volatile solvent is evaporated to form a thin film of an organic alignment agent on the glass substrate. These organic alignment agents are characterized by having a polar end group considered to be attracted to a polar glass surface and a nonpolar long-chain alkyl chain arranged perpendicular to the glass surface. A homeotropic alignment is caused in the liquid crystal compound on such a surface.

[0005] As an inorganic alignment agent, for example,
SiO on the substrate_X Or In_Two O _Three / SnO_Two The vertical
It is known that the film is deposited at an angle,
Produces a meotropic alignment. Other, alkyl side
Polyimide films with chains can also be used in homeotropic
It is used as a pick alignment film.

However, all of the conventional alignment agents give homeotropic alignment to a liquid crystal compound only on a glass substrate, and are not very suitable for alignment on a substrate made of a polymer substance such as a plastic film or a plastic sheet. It does not work effectively. The surface of the substrate made of a polymeric material is presumed to have poor affinity for the polar end groups of the conventional aligning agents and, therefore, generally exhibits no or only a little homeotropic alignment. It only shows the orientation. Further, heat treatment at a high temperature is required for forming the polyimide film having an alkyl side chain, but only a few transparent plastic films can withstand baking of the polyimide alignment film and can be used for optical applications.

[0007]

On the other hand, the present applicant has proposed a monomer unit (a) containing a liquid crystal fragment side chain and a side chain containing a monomer unit (b) containing a non-liquid crystal fragment side chain. It has been found that a liquid crystal polymer can be homeotropically aligned on a substrate without using a vertical alignment film, thereby producing a homeotropically aligned liquid crystal film (Japanese Patent Application No. 2000-370978).

Since these side chain type liquid crystal polymers form a film on a substrate without using a vertical alignment film, the Tg of the liquid crystal film is designed to be low. It is desired that these liquid crystal films have improved durability which can be used for applications such as liquid crystal displays. It has been found that durability can be solved by aligning and fixing a homeotropically aligned liquid crystalline composition containing a photopolymerizable liquid crystal compound, and then irradiating the composition with light such as ultraviolet rays (Japanese Patent Application No. 20-284).
01-136848).

However, depending on the material of the substrate and the combination of the liquid crystal polymer and the liquid crystal composition, the homeotropic alignment liquid crystal layer may not have homeotropic alignment in some cases.

The present invention relates to a homeotropic alignment liquid crystal layer formed directly on a substrate by using a side-chain type liquid crystal polymer without using a vertical alignment film, and in particular, a photopolymerizable liquid crystal to a side-chain type liquid crystal polymer. Provided is a method for producing a homeotropically-aligned liquid crystal film that can satisfy the homeotropically-oriented property of a homeotropically-aligned liquid crystal layer formed from a homeotropically-aligned liquid crystal composition containing a compound, regardless of the material of the substrate. It is another object of the present invention to provide a homeotropically-aligned liquid crystal film obtained by the production method. It is another object of the present invention to provide an optical film having a homeotropically-aligned liquid crystal film layer on a substrate.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned objects can be achieved by the following homeotropically-aligned liquid crystalline composition, thereby completing the present invention. Reached.

That is, the present invention provides a side chain type liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer on a substrate not provided with a vertical alignment film, and an anchor coating on a substrate not provided with a vertical alignment film. Coating via a layer, further homeotropically aligns the side chain type liquid crystal polymer in a liquid crystal state, and a method for producing a homeotropically aligned liquid crystal film, characterized in that the alignment is fixed while maintaining the alignment state. .

Further, the present invention provides a homeotropically aligned liquid crystal comprising a side chain type liquid crystal polymer capable of forming a homeotropically aligned liquid crystal layer on a substrate having no vertical alignment film and a photopolymerizable liquid crystal compound. The composition is applied on a substrate not provided with a vertical alignment film via an anchor coat layer, and the liquid crystal composition is homeotropically aligned in a liquid crystal state, and fixed while maintaining the alignment state. And then irradiating the film with light.

According to the manufacturing method of the present invention, the anchor coat layer is formed on the substrate on which the vertical alignment film is not provided, and good homeotropic alignment can be secured by the anchor coat layer.

In the method for producing a homeotropically aligned liquid crystal film, the anchor coat layer is preferably a transparent glassy polymer film.

As the anchor coat layer, a layer in which a liquid crystal layer formed of a side chain type liquid crystal polymer or a liquid crystal composition can ensure homeotropic alignment can be used without any particular limitation. This is preferable for ensuring homeotropic alignment of the liquid crystal layer.

The method for producing a homeotropically aligned liquid crystal film is effective when the material of the substrate is a polymer substance.

As the substrate, various materials such as a polymer substance, a glass substrate, and a metal can be used.
In particular, when the material of the substrate is a polymer substance, the homeotropic alignment property may be reduced depending on the combination of the liquid crystal polymer and the liquid crystalline composition depending on the material.
When a polymer material of such a material is used as a base material, it is effective to provide an anchor coat layer on the substrate to ensure homeotropic orientation.

The present invention also relates to a homeotropically-aligned liquid crystal film obtained by the above method.

Further, according to the present invention, a side chain type liquid crystal polymer or a side chain type liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer on a substrate on which a vertical alignment film is not provided via an anchor coat layer. The present invention relates to an optical film provided with a homeotropically aligned liquid crystal film layer in which a homeotropically aligned liquid crystalline composition containing a polymerizable liquid crystal compound is homeotropically aligned and fixed.

Furthermore, the present invention relates to a liquid crystal display device using the optical film.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, examples of the liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer include a monomer unit (a) containing a liquid crystal fragment side chain and a monomer containing a non-liquid crystal fragment side chain. A side chain type liquid crystal polymer containing the unit (b) is exemplified.

The side chain type liquid crystal polymer can realize homeotropic alignment of the liquid crystal polymer without using a vertical alignment film. The side-chain type liquid crystal polymer is a monomer unit containing a non-liquid crystal fragment side chain having an alkyl chain or the like in addition to the monomer unit (a) containing a liquid crystal fragment side chain of a normal side chain type liquid crystal polymer. (B), by the action of the monomer unit (b) containing a non-liquid crystalline fragment side chain, the nematic liquid crystal phase is developed by, for example, heat treatment to form a nematic liquid crystal phase without using a vertical alignment film. It is presumed that the tropic orientation has been shown.

The monomer unit (a) has a side chain having nematic liquid crystallinity and has, for example, the general formula (a):

Embedded image (However, R ¹ is a hydrogen atom or a methyl group, a is 1 to
A positive integer of 6, X ¹ represents a —CO ₂ — group or —OCO—
R ² is a cyano group, an alkoxy group having 1 to 6 carbon atoms,
A fluoro group or an alkyl group having 1 to 6 carbon atoms, and b and c represent an integer of 1 or 2. )).

The monomer unit (b) has a linear side chain. For example, the monomer unit (b) has the general formula (b):

Embedded image (Where R ³ is a hydrogen atom or a methyl group, R ⁴ is an alkyl group having 1 to 22 carbon atoms, a fluoroalkyl group having 1 to 22 carbon atoms, or a general formula (b1):

Embedded image However, d is a positive integer of 1 to 6, and R ⁵ is 1 to 6 carbon atoms.
Represents an alkyl group. )).

The ratio of the monomer unit (a) to the monomer unit (b) is not particularly limited, and varies depending on the type of the monomer unit. Because the liquid crystal polymer does not show liquid crystal monodomain alignment,
It is preferable that (b) / {(a) + (b)} = 0.01 to 0.8 (molar ratio). In particular, it is more preferably 0.1 to 0.5.

The liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer includes a monomer unit (a) containing the liquid crystal fragment side chain and a monomer unit containing a liquid crystal fragment side chain having an alicyclic ring structure. Side chain type liquid crystal polymers containing (c).

According to the side chain type liquid crystal polymer, homeotropic alignment of the liquid crystal polymer can be realized without using a vertical alignment film. The side chain type liquid crystal polymer,
It has a monomer unit (c) containing a liquid crystal fragment side chain having an alicyclic ring structure in addition to a monomer unit (a) containing a liquid crystal fragment side chain of a normal side chain type liquid crystal polymer. Therefore, by the action of the monomer unit (c), even if a vertical alignment film is not used,
For example, it is presumed that the liquid crystal is brought into a liquid crystal state by a heat treatment, a nematic liquid crystal phase is developed, and a homeotropic alignment is exhibited.

The monomer unit (c) has a side chain having nematic liquid crystallinity, and has, for example, the general formula (c):

Embedded image (However, R ⁶ hydrogen atom or methyl group, h is 1-6
Is an X ² —CO ₂ — group or an —OCO— group, e and g are integers of 1 or 2, f is an integer of 0 to 2, R ⁷ is a cyano group, and a carbon number of 1 to 2. Represents 12 alkyl groups. )).

The ratio between the monomer units (a) and (c) is not particularly limited, and varies depending on the type of the monomer units. Because the liquid crystal polymer does not show liquid crystal monodomain alignment,
It is preferable that (c) / {(a) + (c)} = 0.01 to 0.8 (molar ratio). In particular, it is more preferably 0.1 to 0.6.

The liquid crystal polymer which can form the homeotropic alignment liquid crystal layer is not limited to those having the above-mentioned monomer units, and the above-mentioned monomer units can be appropriately combined.

The weight average molecular weight of the side chain type liquid crystal polymer is preferably from 2,000 to 100,000. By adjusting the weight average molecular weight in such a range, the performance as a liquid crystal polymer is exhibited. If the weight average molecular weight of the side chain type liquid crystal polymer is too small, the film formability of the alignment layer tends to be poor. Therefore, the weight average molecular weight is more preferably at least 25,000. On the other hand, if the weight average molecular weight is too large, the orientation as a liquid crystal tends to be poor and it is difficult to form a uniform alignment state. Therefore, the weight average molecular weight is more preferably 50,000 or less.

The side chain type liquid crystal polymer exemplified above is:
It can be prepared by copolymerizing an acrylic monomer or a methacrylic monomer corresponding to the monomer units (a), (b) and (c). The monomers corresponding to the monomer units (a), (b) and (c) can be synthesized by a known method. The copolymer can be prepared according to a conventional polymerization method of an acrylic monomer such as a radical polymerization method, a cationic polymerization method, or an anion polymerization method. When the radical polymerization method is applied, various polymerization initiators can be used, but the decomposition temperature of azobisisobutyronitrile or benzoyl peroxide is not high, and decomposes at an intermediate temperature that is not low. Are preferably used.

The side chain type liquid crystal polymer can be mixed with a photopolymerizable liquid crystal compound to form a liquid crystal composition.
The photopolymerizable liquid crystal compound is a liquid crystal compound having at least one unsaturated double bond such as an acryloyl group or a methacryloyl group as a photopolymerizable functional group, and a nematic liquid crystal compound is awarded. . Such a photopolymerizable liquid crystal compound includes the monomer unit (a)
Acrylate or methacrylate that can be used. As the photopolymerizable liquid crystal compound, a compound having two or more photopolymerizable functional groups is preferable for improving durability. As such a photopolymerizable liquid crystal compound, for example,

Embedded image (Wherein, R represents a hydrogen atom or a methyl group, and A and D each independently represent a 1,4-phenylene group or a 1,4-
X is each independently -COO.
—, —OCO— or —O—, wherein B is 1,4-phenylene, 1,4-cyclohexylene, 4,4′-
A biphenylene group or a 4,4′-bicyclohexylene group, and m and n each independently represent an integer of 2 to 6. )) And the like. Further, as the photopolymerizable liquid crystal compound, a compound in which the terminal “H ₂ C ＝ CR—CO ₂ —” in Chemical formula 5 is substituted with a vinyl ether group or an epoxy group,
"- (CH _{2) m} -" and / or "- (CH _{2) n}
- "and" ^{_{- (CH 2) 3 -C *}} H (CH 3) - (C
H ₂ ) ₂ — ”or“ — (CH ₂ ) ₂ —C ^* H (CH
₃ ) — (CH ₂ ) ₃ — ”.

The above photopolymerizable liquid crystal compound can be brought into a liquid crystal state by heat treatment, for example, a nematic liquid crystal layer can be developed and homeotropically aligned with the side chain type liquid crystal polymer. By crosslinking, the durability of the homeotropically aligned liquid crystal film can be improved.

The ratio of the photopolymerizable liquid crystal compound to the side chain type liquid crystal polymer in the liquid crystalline composition is not particularly limited, and is appropriately determined in consideration of the durability of the obtained homeotropically aligned liquid crystal film. Usually, photopolymerizable liquid crystal compound: side chain type liquid crystal polymer (weight ratio) is preferably about 0.1: 1 to 30: 1, particularly preferably 0.5: 1 to 20: 1.
Further, the ratio is preferably from 1: 1 to 10: 1.

The liquid crystal composition usually contains a photopolymerization initiator. Various photopolymerization initiators can be used without particular limitation. As the photopolymerization initiator, for example, Irgacure (Ir) manufactured by Ciba Specialty Chemicals, Inc.
gacure) 907, 184, 651, 369
And the like. The amount of the photopolymerization initiator added, in consideration of the type of the photopolymerized liquid crystal compound, the mixing ratio of the liquid crystal composition, and the like,
It is added to such an extent that the homeotropic alignment of the liquid crystalline composition is not disturbed. Usually, the amount is preferably about 0.5 to 30 parts by weight based on 100 parts by weight of the photopolymerizable liquid crystal compound. Especially 3
-15 parts by weight are preferred.

The substrate on which the side chain type liquid crystal polymer or liquid crystal composition is applied may be any of a glass substrate, a metal foil, a plastic sheet or a plastic film. The thickness of the substrate is usually about 10 to 1000 μm.

The plastic film is not particularly limited as long as it does not change at the temperature at which it is oriented. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, diacetyl cellulose,
Examples include films made of transparent polymers such as cellulose polymers such as triacetyl cellulose, polycarbonate polymers, and acrylic polymers such as polymethyl methacrylate. Also, polystyrene, styrene-based polymers such as acrylonitrile-styrene copolymer, polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, olefin-based polymers such as ethylene-propylene copolymer, vinyl chloride-based polymer,
A film made of a transparent polymer such as an amide polymer such as nylon or aromatic polyamide may also be used. Furthermore, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers Films made of transparent polymers such as polymers, epoxy polymers and blends of the above polymers are also included. Among these, plastic films such as triacetyl cellulose, polycarbonate, norbornene polyolefin and the like which have high hydrogen bonding properties and are used as optical films are awarded.

Examples of the metal film include a film formed of aluminum or the like.

Examples of the plastic film include Zeonor (trade name, manufactured by Nippon Zeon Co., Ltd.), Zeonex (trade name, manufactured by Nippon Zeon Co., Ltd.), and Arton (trade name, manufactured by Zeon Corporation).
A plastic film made of a polymer substance having a norbornene structure such as JSR Corporation has excellent optical characteristics. Since these polymer substances (plastic films) have very small optical anisotropy, the oriented liquid crystal film layer of the liquid crystalline composition formed on the plastic film transfers the oriented liquid crystal film layer to another plastic film. Instead, it can be used as it is as a homeotropic alignment retardation film for an optical film such as for optical compensation of a liquid crystal display.
Further, with respect to the oriented liquid crystal film layer of the liquid crystalline composition formed on a metal film such as a plastic film or aluminum foil having optical anisotropy, after the liquid crystalline composition is formed into an oriented liquid crystal film, a norbornene structure is formed. By transferring directly or via a pressure-sensitive adhesive or adhesive onto a transparent and optically anisotropic small plastic film such as a film or cellulose triacetate having,
It can be used for optical films such as optical compensation films.

As the anchor coat material, metal alkoxides, especially metal silicon alkoxide sols, can be used. The metal alkoxide is usually used as an alcohol-based solution. After the solution is applied to the substrate, the solvent is removed, and the sol-gel reaction is promoted by heating to form a transparent glassy polymer film on the substrate. A metal silicon alkoxide gel layer is formed from the metal silicon alkoxide sol. As a method of applying the metal alkoxide sol solution on a substrate, for example, a roll coating method, a gravure coating method, a spin coating method, a bar coating method, or the like can be employed. As a method for removing the solvent or promoting the reaction, drying at room temperature, drying in a drying furnace, heating on a hot plate, or the like is usually used.

The thickness of the anchor coat layer is a factor contributing to the adhesion to the homeotropically aligned liquid crystal layer. In particular, the homeotropically aligned liquid crystal layer contains a side chain type liquid crystal polymer and a photopolymerizable liquid crystal compound. When the homeotropically aligned liquid crystal composition is formed of a homeotropically aligned liquid crystal composition, the homeotropically aligned liquid crystal layer has a three-dimensional structure formed by cross-linking. And the thickness is adjusted to a thickness corresponding to the thickness of the homeotropically aligned liquid crystal film formed on the anchor coat layer. Generally, it is almost determined by the conditions for forming the homeotropic alignment liquid crystal layer and the anchor coat layer. The thickness is preferably in the range of about 0.05 to 1 μm.

The method for applying the side chain type liquid crystal polymer or the liquid crystalline composition to a substrate is a solution coating method using a solution obtained by dissolving the side chain type liquid crystal polymer or the liquid crystalline composition in a solvent or the liquid crystal polymer. Alternatively, a method of melting and applying a liquid crystalline composition by melt coating may be mentioned, and among them, a method of applying a solution of a side chain type liquid crystal polymer or a liquid crystalline composition on a supporting substrate by a solution coating method is preferable. .

The solvent used for preparing the solution varies depending on the type of the side chain type liquid crystal polymer, the photopolymerizable liquid crystal compound and the substrate, and cannot be said unconditionally, but is usually chloroform, dichloromethane, dichloroethane, tetrachloroethane. , Trichloroethylene, tetrachloroethylene, halogenated hydrocarbons such as chlorobenzene, phenols, phenols such as parachlorophenol, benzene, toluene, xylene, methoxybenzene, 1,
Aromatic hydrocarbons such as 2-dimethoxybenzene, and others, acetone, ethyl acetate, tert-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene bricol monomethyl ether, diethylene glycol dimethyl ether, ethyl cellosolve, butyl cellosolve , 2-pyrrolidone, N-methyl-
2-pyrrolidone, pyridine, triethylamine, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, acetonitrile, butyronitrile, carbon disulfide and the like can be used. The concentration of the solution cannot be determined unconditionally because it depends on the solubility of the side chain type liquid crystal polymer or liquid crystalline composition to be used and the thickness of the finally oriented liquid crystal film to be used.
%, Preferably in the range of 7 to 30% by weight.

The thickness of the homeotropically-aligned liquid crystal film layer made of the coated side chain type liquid crystal polymer or liquid crystal composition is preferably about 1 to 10 μm. In particular, when it is necessary to precisely control the thickness of the homeotropic alignment liquid crystal film, since the film thickness is substantially determined at the stage of coating on the substrate, control of the solution concentration, the film thickness of the coating film, and the like is performed. Need special attention.

As a method of applying a solution of a side chain type liquid crystal polymer or a liquid crystalline composition adjusted to a desired concentration using the above-mentioned solvent to an anchor coat layer on a substrate, for example, a roll coating method, gravure A coating method, a spin coating method, a bar coating method, or the like can be employed. After the coating, the solvent is removed to form a liquid crystal polymer layer or a liquid crystal composition layer on the substrate. The conditions for removing the solvent are not particularly limited, as long as the solvent can be substantially removed and the liquid crystal polymer layer or the liquid crystal composition layer does not flow or does not flow down. Usually, the solvent is removed by using drying at room temperature, drying in a drying oven, heating on a hot plate, or the like.

Next, the side chain type liquid crystal polymer layer or the liquid crystalline composition layer formed on the supporting substrate is brought into a liquid crystal state and homeotropically aligned. For example, heat treatment is performed so that the side chain type liquid crystal polymer or the liquid crystalline composition is in a liquid crystal temperature range, and homeotropic alignment is performed in a liquid crystal state. The heat treatment can be performed by the same method as the above-described drying method. The heat treatment temperature cannot be specified unconditionally because it differs depending on the type of the side chain type liquid crystal polymer or liquid crystal composition to be used and the type of the support substrate.
C, preferably in the range of 70 to 200C. The heat treatment time varies depending on the heat treatment temperature and the type of the side chain type liquid crystal polymer or the liquid crystal composition or the substrate to be used. Is selected. If the time is shorter than 10 seconds, homeotropic alignment may not be sufficiently formed.

After the heat treatment, a cooling operation is performed. The cooling operation can be performed by bringing the homeotropically-aligned liquid crystal film after the heat treatment from the heating atmosphere in the heat treatment operation to room temperature. Also, forced cooling such as air cooling or water cooling may be performed. The alignment of the homeotropic alignment layer of the side chain type liquid crystal polymer is fixed by cooling to a temperature equal to or lower than the glass transition temperature of the side chain type liquid crystal polymer.

In the case of a liquid crystal composition, the homeotropic liquid crystal alignment layer thus fixed is irradiated with light to polymerize or crosslink the photopolymerizable liquid crystal compound, thereby fixing the photopolymerizable liquid crystal compound. To obtain a homeotropically aligned liquid crystal film having improved durability. The light irradiation is performed by, for example, ultraviolet irradiation. The ultraviolet irradiation condition is preferably in an inert gas atmosphere in order to sufficiently promote the reaction. Usually, a high-pressure mercury ultraviolet lamp having an illuminance of about 80 to 160 mW / cm ² is typically used. Other types of lamps such as metahalide UV lamps and incandescent tubes can also be used. It should be noted that the liquid crystal layer surface temperature at the time of ultraviolet irradiation is appropriately adjusted by a cold mirror, water cooling or other cooling treatment, or increasing the line speed so that the liquid crystal layer surface temperature falls within the liquid crystal temperature range.

In this way, a thin film of the side chain type liquid crystal polymer or the liquid crystalline composition is formed, and is fixed while maintaining the orientation, whereby a homeotropically oriented liquid crystal film is obtained. The alignment liquid crystal layer has molecules aligned in the same direction. Therefore, it is well known that the freezing or stabilization of the orientation vector of the oriented liquid crystal layer and the preservation of its anisotropic physical properties are achieved, and such thin films have been confirmed for their optical properties and are used in various applications. Is done. The alignment liquid crystal layer is a thin film having a uniaxial positive birefringence.

The orientation of the homeotropically aligned liquid crystal layer obtained as described above can be quantified by measuring the optical phase difference of the liquid crystal layer at an angle inclined from normal incidence. In the case of homeotropically aligned liquid crystal films, this retardation value is symmetric about normal incidence. Several methods can be used to measure the optical phase difference,
For example, an automatic birefringence measuring device (Oak) and a polarizing microscope (Olympus) can be used. This homeotropic alignment liquid crystal film looks black between crossed Nicol polarizers. Thus, the homeotropic orientation was evaluated.

The thus obtained homeotropically aligned liquid crystal film is used as an optical film. The oriented liquid crystal film may be used after being peeled off from the substrate, or may be used as it is as an oriented liquid crystal layer formed on the substrate without being peeled off.

The homeotropically aligned liquid crystal film is used as an optical film. For example, when a homeotropically-aligned liquid crystal film is manufactured using a uniaxially-aligned retardation film as a base material, a retardation film having a wide viewing angle is obtained, and by applying this to an STN-type liquid crystal display device, the display of the liquid crystal display device is performed. The characteristics, particularly the viewing angle characteristics, can be significantly improved.

[0055]

EXAMPLES Hereinafter, one embodiment of the present invention will be described with reference to examples, but it is needless to say that the present invention is not limited to the examples. The resulting homeotropically aligned liquid crystal film was evaluated for orientation and adhesion. Table 1 shows the results.

Example 1 Ethyl silicate 2 as a sol solution for anchor coating
% Solution (trade name Colcoat P, manufactured by Colcoat Co., Ltd.)
Was applied by bar coating to a plastic film (35 μm) using polycarbonate (manufactured by Kanegafuchi Chemical Co., Ltd.) as a polymer material. Next, the mixture was heated at 120 ° C. for 1 minute to form a transparent glassy polymer film (0.3 μm).

[0057]

Embedded image The side chain type liquid crystal polymer 12.5 represented by the above formula 6 (the number in the formula represents mol% of the monomer unit and is represented by a block body for convenience, and the weight average molecular weight is 5000)
1 part by weight of a photopolymerizable liquid crystal compound (Palicolor LC242, manufactured by BASF) showing a nematic liquid crystal layer
A solution prepared by dissolving 2.5 parts by weight and 5 parts by weight of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) in 75 parts by weight of cyclohexanone was spin-coated on an anchor coat layer provided on a film substrate. Coated. Then, the liquid crystal layer was heated at 130 ° C. for 1 minute, and then cooled to room temperature at a stretch, whereby the liquid crystal layer was homeotropically aligned, vitrified while maintaining the alignment, and the homeotropically aligned liquid crystal layer (2 μm) was fixed. Furthermore, a homeotropic alignment liquid crystal film was produced by irradiating the fixed homeotropic alignment liquid crystal layer with ultraviolet rays.

(Homeotropic Alignment) When the sample (homeotropic alignment liquid crystal film with substrate) was observed from a direction perpendicular to the film surface by a polarizing microscope with crossed Nicols, nothing was seen from the front. Was. This confirmed the homeotropic alignment. That is, it was found that no optical phase difference occurred. By tilting this film, light enters obliquely,
Similarly, when observed by crossed Nicols, light transmission was observed.

The optical retardation of the film was measured by an automatic birefringence measuring device. Measurement light was incident on the sample surface perpendicularly or obliquely, and homeotropic alignment was confirmed from a chart of the optical phase difference and the angle of incidence of the measurement light. In homeotropic alignment, the phase difference (front phase difference) in the direction perpendicular to the sample surface is almost zero. For this sample, when the phase difference was measured obliquely in the slow axis direction of the liquid crystal layer, it was determined that homeotropic alignment was obtained because the phase difference value increased with an increase in the incident angle of the measurement light. did it. From the above,
The homeotropic orientation was determined to be good.

(Adhesion Test) In order to examine the adhesion, a peel test was performed. As a peeling test, an adhesive tape having an adhesive strength of 7 N / 25 mm as measured by JISZ 0237-1991 was put on the obtained homeotropically aligned liquid crystal film in a 1 mm square cut grid pattern, and was adhered to the liquid crystal surface. After leaving the tape at room temperature for 12 hours, the tape was peeled off, and the unpeeled portion was removed by an optical method (a method in which a film was sandwiched between polarizing plates to observe whether a difference in phase difference was observed due to a difference in color change, or Method of comparing the values obtained by the phase difference measurement before and after the test)
After recording, the degree of adhesion was determined by the following equation. The degree of adhesion is 95
%Met. Adhesion degree (%) = (part that did not peel / part where tape was applied) × 100.

[0061] In Example 1, 1 a thickness of the homeotropic alignment liquid crystal _layer. 2 [mu] m, the thickness of the anchor coat layer _0. Except that the 1μm in the same manner as in Example 1 a homeotropic alignment liquid crystal film Produced. The obtained homeotropic alignment liquid crystal film was evaluated in the same manner as in Example 1. The homeotropic orientation was good. The degree of adhesion was 100%.

Reference Example 1 In Example 1, the thickness of the anchor coat layer was 0.1 μm _.
A homeotropically-aligned liquid crystal film was prepared in the same manner as in Example 1 except that m was used. The obtained homeotropic alignment liquid crystal film was evaluated in the same manner as in Example 1. The homeotropic orientation was good.
The degree of adhesion was 5%.

Reference Example 2 In Example 1, the thickness of the anchor coat layer was 0.2 μm _.
A homeotropically-aligned liquid crystal film was prepared in the same manner as in Example 1 except that m was used. The obtained homeotropic alignment liquid crystal film was evaluated in the same manner as in Example 1. The homeotropic orientation was good.
The degree of adhesion was 10%.

Comparative Example 1 The same operation as in Example 1 was performed except that the anchor coat layer was not formed. The obtained film was evaluated in the same manner as in Example 1. Homeotropic alignment could not be confirmed. When observed from the front, it is cloudy, and it is considered that the liquid crystal director is present in all directions, and the orientation of the liquid crystal is disordered. The degree of adhesion was 100%.

[0065]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 7/06 CER C08J 7/06 CER 4J026 CEY CEY 4J100 CEZ CEZ G02B 5/30 G02B 5/30 // C08L 51:00 C08L 51:00 F term (reference) 2H049 BA04 BA06 BA42 BB42 BC04 BC05 BC22 2H091 FA11X FA11Z FB02 HA10 JA01 LA12 LA19 4F006 AA02 AA11 AA12 AA15 AA16 AA17 AA19 AA22 AA32 AA34 AA37 AA37 AA37 AAAB AA37 AAA AAB AA AAB AA A A A A A B A A A A B A A B A A A A B A A A B A A A A A B A A A A B A A B A A A A A B A A A B A A A A A B A A A AA33 AF12 AF35 AG02 AH12 BB12 BC02 4J011 AA05 BA03 CA01 CA08 CB02 DA02 FA07 FB01 PA69 PB40 PC02 PC08 QA12 QC07 RA03 UA01 VA01 WA10 4J026 AA45 AC36 BA28 BB10 DB05 DB06 DB36 FA05 GA06 BA08 BA08P08BA08BA08 BA08BA08P08P08P BC04Q BC43P BC43Q BC44P BC44Q CA04 DA66 JA39 JA43

Claims (7)

[Claims] 1. A side chain type liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer on a substrate not provided with a vertical alignment film is provided on a substrate not provided with a vertical alignment film via an anchor coat layer. A method for producing a homeotropically-aligned liquid crystal film, which comprises applying, further homeotropically aligning the side-chain type liquid crystal polymer in a liquid crystal state, and fixing the aligned state. 2. A homeotropic alignment liquid crystal composition comprising a side chain type liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer on a substrate not provided with a vertical alignment film and a photopolymerizable liquid crystal compound, On a substrate not provided with a vertical alignment film, coating via an anchor coat layer, further homeotropically aligning the liquid crystalline composition in a liquid crystal state, and fixing the liquid crystal composition while maintaining the alignment state, A method for producing a homeotropically aligned liquid crystal film, comprising irradiating light. 3. The method according to claim 1, wherein the anchor coat layer is a transparent glassy polymer film. 4. The method for producing a homeotropically aligned liquid crystal film according to claim 1, wherein the material of the substrate is a polymer substance. 5. A homeotropically-aligned liquid crystal film obtained by the production method according to claim 1. 6. A side chain type liquid crystal polymer or a side chain type liquid crystal polymer and a photopolymerizable liquid crystal capable of forming a homeotropic alignment liquid crystal layer on a substrate on which a vertical alignment film is not provided via an anchor coat layer. An optical film provided with a homeotropically aligned liquid crystal film layer in which a homeotropically aligned liquid crystalline composition containing a compound is homeotropically aligned and fixed. 7. A liquid crystal display device to which the optical film according to claim 6 is applied.