JPH0720434A - Production of liquid crystal high-polymer film - Google Patents

Abstract

PURPOSE:To provide the process for production of the liquid crystal high- polymer film having an orientation structure in which the average orientation direction of liquid crystal molecules constituting the film inclines with a substrate. CONSTITUTION:The liquid crystal high polymer which turns to a glass state at a temp. below the liquid crystal transition point is oriented in the state inclined in the average orientation direction of the liquid crystal high polymer at 5 to 85 deg. with the substrate plane at the temp. above the liquid crystal transition point and is then cooled to the temp. below the liquid crystal transition point to immobilize the liquid crystal state inclined in the orientation direction of the liquid crystal high polymer with the substrate plane in the method for obtaining the film formed by immobilizing the orientation of the liquid crystal high polymer onto the substrate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a liquid crystalline polymer film useful as a high-performance optical element.

[0002]

2. Description of the Related Art A birefringent polymer film has a refractive index anisotropy and functions as an optical element for controlling the phase and polarization state of light. Industrially, there are various uses such as a retardation film for improving the image quality of liquid crystal displays, a half-wave plate, and a quarter-wave plate.

Most conventional birefringent polymer films are obtained by stretching a film of polycarbonate or the like. There is a limit to the improvement of the performance because the means for controlling the physical properties such as the refractive index or the birefringence is substantially only the stretching operation which is a processing technique. In particular, there has been a limit to the control of the three-dimensional refractive index structure, which has recently been strongly demanded.

On the other hand, an optical material using a liquid crystalline polymer has a greater birefringence than a stretched film, and the orientation behavior of the liquid crystalline polymer is rich in variety, so that the refractive index or the birefringence is high. It has a great feature that the optical properties of can be controlled freely. A typical liquid crystal polymer is one having nematic alignment. When these are aligned on the substrate, a homogeneous alignment in which the alignment direction of the liquid crystal molecules is aligned substantially parallel to the substrate or a homeotropic alignment in which the liquid crystal molecules are aligned substantially vertically is obtained.

The inventors of the present invention have conducted extensive studies to create a new optical material by utilizing the characteristics of such a liquid crystalline polymer, and as a result, succeeded in developing it as a color compensating plate for liquid crystal displays. Proposed (JP-A-3-291601, JP-A-3-291620).

These optical materials were excellent in various optical characteristics as compared with the conventional retardation film made of a stretched polymer film, but there was still a limit in controlling the refractive index in three-dimensional directions.

[0007]

If the average alignment direction of the polymer liquid crystal can be realized in an alignment state (tilt alignment) in which the average alignment direction of the polymer liquid crystal is tilted from the plane of the substrate, the optical alignment using the polymer liquid crystal film produced by fixing the conventional homogeneous alignment is achieved. The flexibility of controlling the refractive index is increased compared to the material. The present inventors have focused their attention on this tilt alignment for the purpose of improving the performance of an optical material made of a polymer liquid crystal film or exhibiting new properties, and have made diligent studies on the type of liquid crystal polymer, the alignment method, and its fixing method. As a result, the present invention was finally reached. The present invention provides a method for producing a liquid crystalline polymer film having an alignment structure in which the average alignment direction of liquid crystal molecules constituting the film is inclined with respect to the substrate.

[0008]

The present invention relates to a method for obtaining a film in which a liquid crystalline polymer on a substrate is orientation-fixed, wherein the liquid crystalline polymer which is in a glass state at a temperature below the liquid crystal transition point is added to the substrate. At the temperature above the liquid crystal transition point, the average alignment direction of the liquid crystalline polymer is 5 with respect to the plane of the substrate.
The liquid crystallinity is characterized by fixing the liquid crystal state in which the alignment direction of the liquid crystalline polymer is tilted with respect to the substrate plane by orienting in a state of tilting from 85 ° to 85 ° and then cooling to a temperature below the liquid crystal transition point. It is a method for producing a polymer film.

One of the preferred embodiments of the present invention is a method for producing the above-mentioned liquid crystalline polymer film, wherein the substrate has a preferential pretilt direction, and yet another preferred embodiment is that the liquid crystalline polymer is mainly used. Polyester containing an aromatic unit having a substituent having an alkyl group having 3 or more carbon atoms in the chain, polyester containing an aliphatic unit having a carbon number of 3 or more in the main chain, and an aromatic having a fluorine or fluorine-containing substituent in the main chain The method for producing a liquid crystal polymer film as described above, which essentially includes at least one polyester selected from the group consisting of polyesters containing a group unit.

The present invention will be described in detail below. The alignment state in which the average orientation direction of the liquid crystalline polymer in the present invention is inclined with respect to the substrate plane, the average orientation direction of the liquid crystal molecules in the liquid crystal layer present between the substrate interface and the opposite interface,
It refers to a state in which the alignment state is not substantially parallel to the substrate or even substantially perpendicular to the substrate. If the angle between the plane of the substrate and the average alignment direction of the liquid crystal molecules is defined as a tilt angle, the former corresponds to a tilt angle of 0 ° and the latter corresponds to 90 °.

The preferred tilt angle employed in the manufacturing method of the present invention is in the range of 5 ° to 85 °, preferably 8 ° to 80 °, and more preferably 10 ° to 7 °.
It is in the range of 0 °. Such an alignment state is called tilt alignment. If the tilt angle is less than 5 °, or 85 °
When it is larger than the above values, the orientations are substantially the same as the homogeneous orientation and the homeotropic orientation, respectively, and the desired three-dimensional optical characteristics cannot be freely controlled.

There are several types of tilt alignment. A typical example is tilt alignment in which the angle between the alignment direction of liquid crystal molecules in the liquid crystal layer and the plane of the substrate is almost constant at any position in the film thickness direction. Further, near the interface of the substrate, the liquid crystal molecules have a homogeneous orientation or an orientation close thereto, and the liquid crystal molecules gradually rise toward the interface on the side opposite to the substrate, and a tilt orientation in which homeotropic orientation or an orientation state close to that is obtained, or In the opposite case, that is, in the vicinity of the substrate interface, the liquid crystal molecules have homeotropic orientation or an orientation close thereto, and there is a tilt orientation in which the liquid crystal molecules gradually approach homogeneous orientation as they approach the interface on the opposite side of the substrate. . Tilt alignment in which the angle between the liquid crystal molecules and the substrate plane is constant at any point in the film thickness direction, and tilt alignment in which this angle continuously changes in the film thickness direction (hybrid alignment)
Any of the above is included in the range of tilt orientation in the present invention. In the latter case, the average value of the angles that continuously change in the film thickness direction is the tilt angle in the present invention.

The liquid crystalline polymer used in the present invention has a nematic phase as a liquid crystal phase. That is, the individual liquid crystal molecules are oriented at an angle with respect to the plane of the substrate, but the projection components on the substrate always have a certain orientation structure.

The liquid crystalline polymer used in the present invention has a tilt alignment structure at a temperature above the liquid crystal transition point and can be fixed in a glass state without damaging the structure (glass fixing ability). All can be used. The following are liquid crystal polymers having these properties.

Liquid crystalline polymer having tilt orientation ability and glass fixing ability, composition of liquid crystalline polymer having tilt orientation ability and glass fixing ability and liquid crystal polymer having glass fixing ability, tilt Composition of liquid crystalline polymer having aligning ability and glass fixing ability with other liquid crystalline polymer, composition of liquid crystalline polymer having tilt aligning ability and liquid crystalline polymer having glass fixing ability object.

Examples of the liquid crystal polymer used include main chain type liquid crystal polymers such as polyester, polyamide, polycarbonate and polyester imide, and side chain type liquid crystal polymers such as polyacrylate, polymethacrylate, polymalonate and polysiloxane. be able to. Among them, polyester is preferable from the viewpoint of easiness of synthesis, orientation, glass transition point and the like.

The liquid crystalline polyester having tilt alignment ability is an aromatic unit having a substituent having an alkyl group having 3 or more carbon atoms in its main chain, a unit having an alkyl skeleton having 3 or more carbon atoms, or fluorine or A polyester containing an aromatic unit having a fluorine substituent as a constituent component can be mentioned. These structural units are exemplified below.

[0018]

[Chemical 1]

(Here, A and B respectively have 3 to 1 carbon atoms.
2 straight or branched alkyl groups, -OR, -COO
R, -OCOR (R is a straight-chain or branched alkyl group having 12 carbon number of _{3), - O (CH 2 CH} 2 O) n R ', -
_{COO (CH 2 CH 2 O)} n R ', - OCO (CH 2 C
H ₂ O) _n R ′ (R ′ represents a methyl group or an ethyl group) is shown. )

[0020]

[Chemical 2]

(Here, R "represents a linear or branched alkyl group having 3 to 12 carbon atoms)

[0022]

[Chemical 3]

Of these, the following units are particularly preferable.

[0024]

[Chemical 4]

[0025]

[Chemical 5]

[0026]

[Chemical 6]

Etc.

As the constitutional unit of polyester, (a)
A unit derived from a dicarboxylic acid (hereinafter referred to as a dicarboxylic acid unit), (b) a unit derived from a diol (hereinafter referred to as a diol unit), and (c) having a carboxyl group and a hydroxyl group simultaneously in one unit. Examples thereof include units derived from oxycarboxylic acids (hereinafter referred to as oxycarboxylic acid units). The polyester is appropriately selected from these units. The structure is (a) +
There are (b) type, (a) + (b) + (c) type, and (c) single type. A polyester containing at least one of the structural units (a), (b) and (c) described above effectively acts as a tilt-aligned polymer. The proportion of these units in the polyester is in the range of 1 to 50 mol%, preferably 3 to 40 mol%, more preferably 5 to 30 mol%. If the amount of the units necessary for exhibiting these tilt alignment properties is less than 1 mol%, the desired tilt alignment cannot be obtained, which is not preferable. On the other hand, if it is more than 50 mol%, adverse effects such as a decrease in liquid crystal alignment and a decrease in film flexibility are unfavorable.

Most of these polymers have bulky substituents, fluorine-containing substituents, etc., or contain aromatic units whose main chain bonds are in the meta or ortho position, and therefore are generally It has the ability to immobilize glass.
Regarding tilt-oriented polymers that can be fixed on glass,
It can be used in the present invention alone or in the form of a composition in combination with other liquid crystalline polymers (in the above cases, and). Specific examples of these polymers are shown below.

[0030]

[Chemical 7]

Polymer composed of structural units

[0032]

[Chemical 8]

Polymer composed of structural units of

[0034]

[Chemical 9]

Polymer composed of structural units of

[0036]

[Chemical 10]

Polymer composed of structural units of

[0038]

[Chemical 11]

Polymer composed of structural units of

[0040]

[Chemical 12]

Polymer composed of the structural units of

[0042]

[Chemical 13]

Polymer composed of structural units of

[0044]

[Chemical 14]

Polymer composed of structural units of

[0046]

[Chemical 15]

Polymer composed of structural units of

[0048]

[Chemical 16]

Polymer composed of the structural units of

[0050]

[Chemical 17]

Polymers composed of structural units of

Further, even a polymer having a tilt alignment ability but not a glass fixing ability can be fixed on a glass by combining it with another liquid crystalline polymer capable of fixing a glass,
It can be used in the present invention (in the above cases).

Examples of liquid crystalline polymers that can be fixed on glass are shown below. These are liquid crystalline polymers capable of taking a glassy state at a temperature lower than the liquid crystal phase, and polymers containing ortho-substituted aromatic units having ortho-positioned main chain bonds as constituents are particularly preferably used. Specific examples include catechol units, salicylic acid units, phthalic acid units, 2,3-naphthalenediol units, 2,3-naphthalenedicarboxylic acid units, and those having a substituent on the benzene ring as shown below. You can

[0054]

[Chemical 18]

Etc.

(X is hydrogen, halogen such as Cl or Br,
An alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and an aryl group such as a phenyl group are shown. Also, k is 0 to 2).

Among these, the following can be exemplified as particularly preferable examples.

[0058]

[Chemical 19]

[0059]

[Chemical 20]

The glass-immobilizable liquid crystalline polymer used first contains such ortho-substituted aromatic units, but other units constituting the polyester, (a) dicarboxylic acid units, (b) diol units and (c). ) Examples of oxycarboxylic acid units are shown below.

As the dicarboxylic acid unit (a), the following can be exemplified.

[0062]

[Chemical 21]

(Y is hydrogen, halogen such as Cl or Br,
An alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and an aryl group such as a phenyl group are shown. Also, l is 0 to 2),

[0064]

[Chemical formula 22]

[0065]

[Chemical formula 23]

Etc.

Examples of the diol unit (b) include the following.

[0068]

[Chemical formula 24]

(Z is hydrogen, halogen such as Cl or Br,
An alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and an aryl group such as a phenyl group are shown. Also, m is 0 to 2),

[0070]

[Chemical 25]

[0071]

[Chemical formula 26]

Etc.

As the oxycarboxylic acid unit (c), the following can be exemplified.

[0074]

[Chemical 27]

Etc.

(W is hydrogen, halogen such as Cl or Br,
An alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and an aryl group such as a phenyl group are shown. Also, p is 0 to 2).

The molecular weight of these polymers can be determined in various solvents such as phenol / tetrachloroethane (60/40).
The logarithmic viscosity measured at 30 ° C. in a mixed solvent is preferably 0.05 to 3.0, more preferably 0.07 to 2.
The range is 0. When the logarithmic viscosity is less than 0.05,
The strength of the obtained polymer liquid crystal becomes weak, which is not preferable. On the other hand, when it is more than 3.0, the viscosity at the time of forming the liquid crystal is too high, which causes problems such as deterioration of alignment property and increase of time required for alignment. Further, the glass transition point of these polyesters is also important and affects the stability of orientation after the orientation is fixed. Although it depends on the application, it is generally desired that the glass transition point be 30 ° C. or higher, particularly 50 ° C. or higher, considering that the glass transition point is to be used near room temperature. When the glass transition point is lower than 30 ° C., the liquid crystal structure once immobilized may change when used near room temperature, and the function derived from the liquid crystal structure deteriorates, which is not preferable.

The method of synthesizing these polymers is not particularly limited, and they are synthesized by a polymerization method known in the art, for example, a melt polymerization method or an acid chloride method using a corresponding acid chloride of dicarboxylic acid. In the case of synthesizing by a melt polymerization method, it can be produced, for example, by polymerizing an acetylated product of a corresponding dicarboxylic acid and a corresponding diol at high temperature under high vacuum, and the molecular weight can be easily controlled by controlling the polymerization time or controlling the charging composition. .
In order to accelerate the polymerization reaction, a conventionally known metal salt such as sodium acetate can be used. When the solution polymerization method is used, a desired amount of dicarboxylic acid dichloride and diol are dissolved in a solvent and heated in the presence of an acid acceptor such as pyridine to easily obtain the target polyester.

Composition (ie mixture) as liquid crystalline polymer
When (1) is used (the above, and), the proportion of the liquid crystalline polymer having the tilt alignment ability in the composition varies depending on the desired tilt angle, but cannot be unconditionally specified. Is in the range of 1 to 95% by weight, preferably 5 to 90% by weight.

Next, the substrate for orientation used in the present invention will be described. The substrate must first have the property of having anisotropy along the substrate surface as in the case of a substrate for homogeneous alignment, but it must also have anisotropy for defining the preferential pretilt direction. preferable. The term "pretilt" as used herein refers to a state in which liquid crystal molecules are aligned near the substrate interface at an angle other than 0 ° with the plane of the substrate. The pretilt direction refers to a direction parallel to the substrate plane from the end closer to the substrate of the molecule to the end farther from the substrate when the molecule rises at an angle. Therefore, the presence of the preferential pretilt direction indicates that the pretilt direction defined here is in a substantially constant direction. If there is no preferential pretilt direction and the substrate in which the pretilt direction is not fixed is used, a region tilted in the opposite direction to the main tilt direction may occur, which may prevent the liquid crystal layer from becoming a monodomain. . Even if the substrate has almost no preferential pretilt direction, it is possible to specify the preferential pretilt direction of the liquid crystal by applying an external force such as an electric field, a magnetic field, or shear, but a substrate having the preferential pretilt direction can be prepared in terms of ease of manufacturing. It is preferable to use.

Examples of the substrate that can be used in the present invention include a substrate having a rubbing-treated polyimide film, a polyvinyl alcohol film, a rubbing-treated or stretched plastic film or sheet, and oblique vapor deposition of silicon dioxide. Examples include membranes. When performing the rubbing treatment, it is preferable to limit the rubbing direction of the surface with a cloth or the like to one direction and not to perform the reciprocating operation in order to clearly define the pretilt direction. The following may be mentioned as the plastic film or sheet. For example, acrylic resin such as polymethyl methacrylate, polyvinyl alcohol, polystyrene, polycarbonate, polyether sulfone, polyphenylene sulfide, polyolefin, polyimide, polyamide imide, polyether imide, polyamide, polyether ketone, polyether ether ketone, polyketone sulfide, polysulfone Typical examples are polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyacetal, epoxy resin and phenol resin.

The film having the tilt-aligned structure of the present invention immobilized thereon is produced using the above-mentioned liquid crystalline polymer or a composition containing the same and a substrate. That is,
The polymer is first applied uniformly on the substrate, then heat-treated at the liquid crystal temperature of the polymer for tilt alignment,
The tilt alignment state is fixed by cooling. The application of the polymer to the substrate is usually performed in a solution state or a molten state.
When preparing a solution, the solvent that can be used depends on the type of polymer, but is usually a halogenated hydrocarbon such as chloroform, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, orthodichlorobenzene, a mixed solvent of these with phenol, tetra Fluorofuran, dimethylformamide,
Examples include dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone and the like. Although the concentration of the solution varies depending on the combination of the polymer and the solvent, it is usually used in the range of 5 to 50% by weight, preferably 10 to 30% by weight. Spin coating method, roll coating method,
A printing method, a dipping / pulling-up method, a curtain coating method or the like can be adopted, and after coating, the solvent is removed by drying. Then, a monodomain tilt alignment structure is completed by a heat treatment operation. The viscosity of the polymer is preferably low in order to assist the orientation by the interfacial effect, and therefore the heat treatment temperature is preferably high.However, the heat treatment temperature is the isotropic phase transition temperature because the polymer has an isotropic phase at a temperature higher than the liquid crystal phase. Must be done at a lower temperature. Further, the obtained tilt angle may differ depending on the heat treatment temperature depending on the polymer, and in that case, it is necessary to set the heat treatment temperature for obtaining the tilt angle according to the purpose. For example, if it becomes necessary to perform heat treatment at a relatively low temperature in order to obtain a tilt structure,
At low temperature, the viscosity of the polymer is high and the time required for orientation becomes long.In such a case, the temperature of the stepwise or gradual heat treatment should be applied after once treating at high temperature to obtain monodomain orientation. The method of lowering the temperature to be effective is effective. In any case, depending on the properties of the polymer,
It is preferable to perform the heat treatment at a temperature not lower than the glass transition temperature and not higher than the isotropic phase transition temperature, generally in the range of 50 ° C to 300 ° C, particularly preferably in the range of 100 ° C to 260 ° C. The heat treatment time required to obtain sufficient orientation in the liquid crystal state on the substrate varies depending on the composition of the polymer and the heat treatment temperature, and cannot be generally stated, but is preferably in the range of 10 seconds to 120 minutes, particularly 30 seconds to 60 minutes. Is preferred. If it is shorter than 10 seconds, the orientation may be insufficient, and if it is longer than 120 minutes, the productivity may be lowered. In this way, it is possible to first obtain uniform tilted nematic alignment over the entire surface of the alignment substrate in the liquid crystal state.

The alignment state thus obtained is then cooled to a temperature not higher than the glass transition point of the polymer liquid crystal, whereby the alignment can be fixed without impairing the alignment uniformity. Generally, when a polymer having a crystal phase at a temperature lower than the liquid crystal phase is used, the orientation in the liquid crystal state may be broken by cooling. In the present invention, since a polymer system having a glass phase is used at a temperature below a temperature range showing a liquid crystal phase, such a phenomenon does not occur, and a completely monodomain tilted state can be fixed. There is no particular limitation on the cooling rate, and it is fixed only by exposing it from the heating atmosphere to an atmosphere having a glass transition point or lower. In addition, forced cooling such as air cooling or water cooling may be performed in order to increase production efficiency. However, the tilt angle obtained depending on the cooling rate may be slightly different depending on the polymer. When such a polymer is used, if the tilt angle needs to be strictly controlled, the cooling operation is also preferably performed under controlled conditions.

The liquid crystalline polymer film on the substrate thus obtained can be used as it is as a transmissive type if the substrate is transparent, and even when a substrate having a low transmittance such as a polyimide substrate is used, It can be used for applications that utilize reflective properties. As another film production method of the present invention, it is possible to temporarily fix the liquid crystalline polymer on these substrates, and then peel off the liquid crystal layer from the substrate and transfer it to another substrate more suitable for optical use. . For example, if the alignment substrate to be used is necessary to obtain the tilt alignment state, but it adversely affects the properties when used as an optical element, the substrate is removed from the liquid crystal layer after alignment and fixation. It can be removed and used. At that time, although the liquid crystal layer itself may not have self-supporting properties depending on the film thickness, a method of fixing it on another substrate, which is preferable in terms of optical properties, with an adhesive or the like can be used.

The thickness of the film is not particularly limited, but the thickness after fixation is usually 0.1 to 50 μm, preferably 0.5 to 30 μm.

The polymer liquid crystal film in which the tilt alignment state is thus fixed may be used as it is, or a transparent plastic protective layer may be provided for surface protection. You may combine with other optical elements, such as a polarizing plate.

As described above, the present invention provides a method for producing a polymer liquid crystal film in which polymer liquid crystal molecules constituting the film are tilt-aligned, which has not been obtained by the prior art. Since it has a completely new optical performance due to the novel alignment structure, it can be used for various optical applications including application to liquid crystal display devices, etc., and is extremely industrially valuable.

(Examples) Examples will be described below, but the present invention is not limited thereto. The analytical methods used in the examples are as follows.

(1) Determination of Polymer Composition The polymer was dissolved in deuterated chloroform or deuterated trifluoroacetic acid, and measured by ^1- NMR at 400 MHz (JNM-GX400 manufactured by JEOL Ltd.).

(2) Measurement of logarithmic viscosity Using an Ubbelohde viscometer, it was measured at 30 ° C. in a phenol / tetrachloroethane (60/40 weight ratio) mixed solvent.

(3) Determination of liquid crystal phase series DSC (DuPont 990 Thermal An)
It was determined by the measurement of the alizer) and observation with an optical microscope (BH2 polarizing microscope manufactured by Olympus Optical Co., Ltd.).

(4) Measurement of Refractive Index The refractive index was measured with an Abbe refractometer (Type-4 manufactured by Atago Co., Ltd.).

Example 1 80 mmol of terephthalic acid, 20 mmol of pimelic acid,
Hydroquinone diacetate 50 mmol, isopropylcatechol diacetate 50 mmol and sodium acetate as a catalyst under nitrogen atmosphere at 280 ° C.
Polymerization was performed at 300 ° C. for 2 hours to synthesize the polymer of formula (1). Next, the obtained polymer was dissolved in tetrachloroethane and then reprecipitated with methanol to obtain 27 g of a purified polymer. This polymer has an inherent viscosity of 0.3
As a result of DSC measurement and polarization microscope observation, the liquid crystal phase was nematic, had a glass phase without a crystal phase in the lower temperature part than the liquid crystal phase, and had a Tg of 118 ° C.

Using this polyester, a 10 wt% tetrachloroethane solution was prepared. This solution was applied on a glass substrate with a rubbing polyimide alignment film, in which the rubbing direction was fixed and the preferential pretilt direction was determined, by a spin coating method, dried, and heat-treated at 220 ° C. for 30 minutes and then cooled to a film thickness of 5 μm. A uniformly aligned transparent liquid crystal film was obtained.

[0095]

[Chemical 28]

Example 2 Using the optical measurement system shown in FIGS. 1 and 2, the liquid crystal film produced in Example 1 was tilted along the rubbing direction of the substrate to obtain the retardation value (birefringence Δn and film thickness). The product of d) was measured. The obtained retardation value was maximized when the tilt angle θ was 24 °, and it was found that this film was a film in which the nematic alignment having a tilt angle of 24 °, that is, the tilt alignment was fixed.

Comparative Example 1 A polymer of formula (2) was synthesized in the same manner as in Example 1 except that catechol diacetate was used instead of isopropyl catechol diacetate. This polymer had a logarithmic viscosity of 0.27, and as a result of DSC measurement and polarization microscope observation, the liquid crystal phase was nematic, had a glass phase without a crystal phase in the lower temperature part than the liquid crystal phase, and had a Tg of 115 ° C. It was
A liquid crystal film was produced in the same manner as in Example 1, and Example 2
The retardation value was measured by the method. The retardation value becomes maximum at θ = 1.8 °, and the tilt angle is 1.8.
It was °. Therefore, the film of this comparative example is
Unlike the above, it was found that the film was a normal nematic film with almost no tilt alignment, and the homogeneous alignment was fixed.

[0098]

[Chemical 29]

Example 3 A polymer of formula (3) and a polymer of formula (4) were synthesized in the same manner as in Example 1. Ηinh of this polymer
Are 0.22 and 0.25, respectively, and both have a glass phase at a temperature lower than the liquid crystal phase, Tg is 110 ° C.,
It was 115 ° C.

Next, using a polymer mixture containing 20 wt% of the polymer of the formula (3) and 80 wt% of the polymer of the formula (4), a tetrachloroethane solution having a concentration of 10 wt% was prepared. This solution was applied onto a polyarylate film having a thickness of 100 μm with a rubbing polyimide alignment film in which the rubbing direction was fixed and the preferential pretilt direction was determined.
After being applied by a printing method, it was dried, heat-treated at 250 ° C. for 30 minutes, and then gradually cooled to 220 ° C. over 30 minutes to obtain a uniformly aligned transparent liquid crystal film having a film thickness of 5.9 μm.

Using this film by the method of Example 2,
When the retardation value was measured while tilting the film, the maximum value was obtained at θ = 30 °. Therefore, this film was found to be a film in which the nematic orientation having a tilt angle of 30 °, that is, the tilt orientation was fixed.

[0102]

[Chemical 30]

Comparative Example 2 A polymer of formula (5) was synthesized in which the t-butylcatechol unit of the polymer of formula (3) was changed to a methylcatechol unit. A liquid crystal film was produced in the same manner as in Example 3 except that the polymer of formula (5) was used instead of the polymer of formula (3). When the retardation value of this film was measured by the method of Example 2, the maximum value was obtained at θ = 1.5 °. Therefore, unlike Example 3, this film was hardly tilt-aligned, and was a normal nematic film in which the director was substantially parallel to the substrate plane.

[0104]

[Chemical 31]

Example 4 The polymer of formula (6) was synthesized in the same manner as in Example 1. ηinh was 0.20, and the polymer was a polymer having a glass phase and a Tg of 107 ° C. at a temperature lower than the liquid crystal phase. Then, the polymer of formula (7) was synthesized in the same manner.
This polymer had a ηinh of 0.20 and was a crystalline polymer having no glass phase below the liquid crystal phase.

Next, a dimethylformamide solution having a concentration of 15 wt% was prepared using a polymer mixture containing the polymer of the formula (6) at 70 wt% and the polymer of the formula (7) at 30 wt%. This solution was applied onto a polyarylate film having a rubbing polyimide alignment film and having a thickness of 100 μm by a printing method and then dried, and the temperature was 250 ° C. × 30.
After the partial heat treatment, it was gradually cooled to 220 ° C. over 30 minutes to obtain a uniformly aligned transparent liquid crystal film having a thickness of 3.5 μm.

By using this film and the method of Example 2,
When the retardation value was measured while tilting the film, the maximum value was obtained at θ = 24 °. Therefore, this film was found to be a film in which the nematic orientation having a tilt angle of 24 °, that is, the tilt orientation was fixed.

[0108]

[Chemical 32]

Example 5 The polymer of formula (8) was synthesized in the same manner as in Example 1. ηinh was 0.15, and the polymer was a polymer having a glass phase and a Tg of 89 ° C. at a temperature lower than the liquid crystal phase. Then, a polymer of formula (9) was synthesized in the same manner. This polymer had a ηinh of 0.17 and had a liquid crystal phase, but was a polymer having a crystal phase without a glass phase at a temperature lower than the liquid crystal phase.

Next, a N-methylpyrrolidone solution having a concentration of 15 wt% was prepared using a polymer mixture containing 80 wt% of the polymer of formula (8) and 20 wt% of the polymer of formula (9). This solution was applied onto a polyethersulfone film having a rubbing polyimide alignment film and having a thickness of 75 μm by a printing method, and then dried to obtain 250 ° C.
After heat treatment for 30 minutes, then rapidly cool to 220 ° C for another 22
Heat treatment was performed for 30 minutes at 0 ° C. to obtain a uniformly aligned transparent liquid crystal film having a film thickness of 5.2 μm.

Using this film and the method of Example 2,
When the retardation value was measured while tilting the film, the maximum value was obtained at θ = 18 °. Therefore, this film was found to be a film in which the nematic orientation having a tilt angle of 18 °, that is, the tilt orientation was fixed.

[0112]

[Chemical 33]

Example 6 The polymer of formula (10) was synthesized in the same manner as in Example 1. ηinh was 0.18, and the polymer was a polymer having a glass phase and a Tg of 109 ° C. at a temperature lower than the liquid crystal phase. Then, a polymer of formula (11) was synthesized in the same manner. This polymer had a ηinh of 0.12 and a Tg of 68 ° C. having a glass phase and no crystal phase at a temperature lower than the liquid crystal phase.

Next, 10 wt% of the polymer of the formula (10),
A phenol / tetrachloroethane mixed solvent (weight ratio: 6/4) solution having a concentration of 15 wt% was prepared using a polymer mixture containing the polymer of the formula (11) in a proportion of 90 wt%. This solution was applied on a polyether sulfone film having a thickness of 75 μm with a rubbing polyimide alignment film by a printing method, dried, and then heat-treated at 250 ° C. for 30 minutes, and then rapidly cooled to 220 ° C. and further at 220 ° C. for 30 minutes. Heat treatment was performed to obtain a uniformly aligned transparent liquid crystal film having a film thickness of 4.8 μm.

Using this film by the method of Example 2,
When the retardation value was measured while tilting the film, the maximum value was obtained at θ = 40 °. Therefore, this film was found to be a film in which the nematic orientation having a tilt angle of 40 °, that is, the tilt orientation was fixed.

[0116]

[Chemical 34]

Example 7 A liquid crystal film was produced in the same manner as in Example 6 except that the heat treatment conditions were changed. That is, after coating by a printing method on a polyether sulfone film, it is dried,
After heat treatment at 240 ° C for 30 minutes, it is rapidly cooled to room temperature and the film thickness is 4.9
A transparent liquid crystal film having a uniform alignment of μm was obtained. This film was a film having a fixed tilt orientation with a tilt angle of 26 °.

Example 8 Polymers of formulas (12) and (13) were synthesized by the acid chloride method. The polymer of the formula (12) showed nematic liquid crystallinity with ηinh of 0.29, but had a crystal phase at a temperature lower than the liquid crystal phase. The polymer of the formula (13) had a ηinh of 0.21 and a Tg of 106 ° C. and was a vitrifying polymer.

Next, using a polymer mixture containing the polymer of the formula (12) in an amount of 5 wt% and the polymer of the formula (13) in an amount of 95 wt%, a phenol / tetrachloroethane mixed solvent having a concentration of 10 wt% (weight ratio 6/4) was used. ) A solution was prepared. This solution was applied by spin coating to a rubbed polyether ether ketone film having a thickness of 75 μm in which the rubbing direction was kept constant and the preferential pretilt direction was determined, and then dried.
It was rapidly cooled to 0 ° C. and further heat treated at 180 ° C. for 60 minutes to obtain a uniformly aligned transparent liquid crystal film having a film thickness of 7.2 μm.

Next, a polyether sulfone film having a thickness of 50 μm was adhered to the liquid crystal layer side of this film using an adhesive, the adhesive was cured, and then only the polyether ether ketone film was gently peeled off to remove the liquid crystal layer. Was transferred onto a polyethersulfone film.

When the retardation value was measured while tilting the film by the method of Example 2 using the film thus produced, the maximum value was obtained at θ = 19 °. Therefore, this film was a film in which the nematic orientation having a tilt angle of 19 °, that is, the tilt orientation was fixed.

[0122]

[Chemical 35]

Example 9 Polymers of formulas (14) and (15) were synthesized by the acid chloride method. The polymer of the formula (14) had a nematic liquid crystallinity with ηinh of 0.12, had a glass phase at a temperature lower than the liquid crystal phase, and had a Tg of 88 ° C. Expression (1
The polymer of 5) has ηinh of 0.13 and Tg of 8
It was a nematic liquid crystalline polymer that vitrified at 4 ° C.

Next, 50 wt% of the polymer of the formula (14) is added,
A polymer mixture containing the polymer of the formula (15) in a proportion of 50 wt% was used to prepare a tetrachloroethane solution having a concentration of 20 wt%. This solution was rubbed to a thickness of 50
A polyphenylene sulfide film having a thickness of μm is coated by a spin coating method and then dried, 210 ° C. × 30
After the partial heat treatment, it was rapidly cooled to 170 ° C. and further heat-treated at 170 ° C. for 30 minutes to obtain a uniformly aligned transparent liquid crystal film having a film thickness of 5.9 μm.

Next, a 50 μm thick triacetyl cellulose film was attached to the liquid crystal layer side of this film using an adhesive, the adhesive was cured, and then the polyphenylene sulfide film was gently peeled off, and the liquid crystal layer was triacetylated. It was copied on a cellulose film.

When the retardation value was measured while tilting the film by the method of Example 2 using the film thus produced, the maximum value was obtained at θ = 26 °. Therefore, this film was a film in which the nematic orientation having a tilt angle of 26 °, that is, the tilt orientation was fixed.

[0127]

[Chemical 36]

Example 10 A vitrifying nematic liquid crystalline polymer having a ηinh of 0.31 and a Tg of 96 ° C. in the formula (16) was synthesized. Separately, a crystalline polymer having ηinh of 0.18 in the formula (17), which exhibits nematic liquid crystallinity at a liquid crystal temperature but has no glass phase, was synthesized. 70wt% of the former and 30wt of the latter
% Of the polymer mixture was used to prepare a tetrachloroethane solution having a concentration of 15 wt%. This solution was applied onto a rubbing polyimide film by a printing method. After drying, it was heat-treated at 230 ° C. for 20 minutes and then rapidly cooled to room temperature.

Next, a 50 μm-thick triacetyl cellulose film was attached to the liquid crystal layer side of this film using an adhesive, the adhesive was cured, and then the polyimide film was gently peeled off to remove the liquid crystal layer from the triacetyl cellulose film. I copied it on film.

When the retardation value was measured while tilting the film by the method of Example 2 using the film thus produced, the maximum value was obtained at θ = 24 °. Therefore, this film was a film in which the nematic orientation having a tilt angle of 24 °, that is, the tilt orientation was fixed.

[0131]

[Chemical 37]

[Brief description of drawings]

FIG. 1 shows a layout of an optical measurement system used for measuring a tilt angle of a liquid crystalline polymer film of the present invention.

FIG. 2 shows the relationship between the axial orientations of the sample of the optical measurement system and the polarizing plate used for measuring the tilt angle of the liquid crystalline polymer film of the present invention.

[Explanation of symbols]

 1 incident light 2 upper polarizing plate 3 liquid crystalline polymer film 4 lower polarizing plate 5 outgoing light 6 spectroscope (retardation measuring device) 7 upper polarizing plate transmission axis 8 rubbing axis direction of substrate of liquid crystalline polymer film 9 lower polarized light Plate transmission axis

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02F 1/1335 510 510 8408-2K 1/1347 9017-2K

Claims (3)

[Claims] 1. A method for producing a film in which a liquid crystalline polymer is alignment-fixed on a substrate, wherein the liquid crystalline polymer which becomes a glass state at a temperature below the liquid crystal transition point is formed on the substrate.
At a temperature above the liquid crystal transition point, the liquid crystal polymer is aligned with the average orientation direction inclined from 5 ° to 85 ° with respect to the plane of the substrate, and then cooled to a temperature below the liquid crystal transition point. A method for producing a liquid crystalline polymer film, which comprises fixing a liquid crystal state in which an alignment direction is inclined with respect to a substrate plane. 2. The method for producing a liquid crystalline polymer film according to claim 1, wherein the substrate has a preferential pretilt direction. 3. A liquid crystalline polymer, a polyester containing an aromatic unit having a substituent having an alkyl group having 3 or more carbon atoms in its main chain, a polyester containing an aliphatic unit having 3 or more carbon atoms in its main chain, and The method for producing a liquid crystalline polymer film according to claim 1, wherein at least one polyester selected from the group consisting of polyesters containing an aromatic unit having a fluorine or fluorine-containing substituent in the main chain is an essential component. .