JPH11181127A - Preparation of oriented film, oriented film and liquid crystal display equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a multiple number of arbitrarily chosen orientations in one same oriented film, which is enabled by a photoorientation technique of a polymeric oriented film to accelerate orientation of a liq. crystal encapsulated in a liq. crystal panel. SOLUTION: Irradiation of ultraviolet rays 7 with a linear polarity is applied to a photosensitive polymeric film with a side chain 4, the main chain consisting of a hydrocarbon, an acrylate, a methacrylate, a siloxane or the like, and the film comprising, at a specific ratio, a substituent such as biphenyl, terphenyl, phenyl benzoate, azobenzene or the like, a side chain comprising a structure combined with a photosensitive group such as a cinnamic group and a side chain combined with no photosensitive group, to obtain an oriented film having an arbitrarily chosen orientation property, while facilitating dimerization reaction of the photosensitive group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an alignment film in which a photosensitive side-chain type polymer film is irradiated with linearly polarized ultraviolet rays. This alignment film promotes the alignment of the liquid crystal sealed in the liquid crystal panel, and is useful for improving the liquid crystal display device (of the manufacturing method).

[0002]

2. Description of the Related Art Compared with a CRT type display device, a liquid crystal display device is "flat and can be installed in a small space", "light and easy to carry", and "high speed video communication because it is a digital image". It is advantageous in that it has low power consumption because it is driven by a low voltage, and is rapidly growing as a powerful video information generating means. Many of the currently popular liquid crystal display devices use twisted nematic liquid crystals.

The general structure of a liquid crystal display device will be described with reference to the schematic sectional view of FIG. The liquid crystal display device (120)
A liquid crystal (122) is sandwiched and sealed between two panels (121, 121). The configuration of the panels (121, 121)
Polarizing plates (123, 123), glass substrates (124, 12)
4), transparent electrodes (125, 125), alignment films (126,
126) are laminated. Light rays from a light source (not shown) outside one of the polarizing plates (123) pass through the liquid crystal display device and pass through to the other polarizing plate (123). The liquid crystal display device changes the alignment state of the liquid crystal molecules (122) to the transparent electrodes (1).
25, 125), and the resulting change in the optical properties of the liquid crystal is reflected by the polarizing plates (123, 125).
23). In the no-voltage state, the liquid crystal molecules are twisted while sequentially changing the angle in the thickness direction. The alignment film controls the alignment direction at the interface of the (126, 126) liquid crystal (the surface in contact with the alignment film), and is indispensable for the configuration of the liquid crystal display device.

FIG. 3 shows an example (rubbing method) of a conventional method of manufacturing the most general alignment film. A high molecular compound (132) such as polyimito is applied to the substrate (131), and the surface is rubbed with a drum (133) wound with a cloth (134) in which nylon or polyester fibers are planted to form an extremely fine groove on the surface. This is a manufacturing method for forming an oriented film. This alignment film has the function of controlling the alignment direction of the liquid crystal along the direction of the groove. In the rubbing method, discharge due to fine dust or static electricity is likely to occur, which is a problem in a liquid crystal panel manufacturing process. In addition to the rubbing method, an oblique evaporation method obtained by obliquely depositing silicon oxide on a substrate has been employed.
This alignment film has the function of controlling the alignment direction of the liquid crystal along the tilt direction of the deposited silicon oxide. This method has problems that it is difficult to maintain the uniformity of the deposition angle and the thickness of the deposited film on the substrate, and the process becomes large. Further, in these methods of manufacturing an alignment film, the alignment direction is limited to only one fixed direction over the entire surface, and it is impossible to form a region in which the alignment direction and the degree are arbitrarily different. When an alignment film having a limited alignment direction is used in a liquid crystal display device, the phase difference increases depending on the direction in which the liquid crystal is viewed (the result is a large viewing angle dependency), and the visible angle becomes narrow.

[0005]

In recent years, attention has been paid to a liquid crystal photo-alignment technique for aligning a (polymer) liquid crystal by using light irradiation as a method for producing an alignment film which solves the above-mentioned problems of the conventional method. ing. This technique is roughly classified into a method using a photodimer reaction, a method using photoisomerization of an azo-based polymer, and a method of applying linearly polarized ultraviolet rays to a liquid crystal vertical alignment film of a polyimide having an alkyl side chain. The conventional liquid crystal optical alignment technology has the following problems. In the method using photodimer reaction or photoisomerization of an azo polymer, the direction of the electric field of irradiated linearly polarized ultraviolet light is orthogonal to the molecular orientation direction of the alignment film.
In a liquid crystal panel, it is difficult to develop a pretilt angle required to prevent defects in liquid crystal alignment. In the method using the polyimide with an alkyl side chain, a pretilt angle can be developed, but in this method, the alkyl side chain is cut by ultraviolet rays, so that fine dust is generated, which is a problem in the production of a liquid crystal panel. The present invention provides a method for manufacturing an alignment film that has solved the above-mentioned problems of the liquid crystal photo-alignment technology.

[0006]

Means for Solving the Problems An object of the present invention to solve the problem is a method for producing a polymer alignment film which promotes the alignment of liquid crystal in a liquid crystal panel. A method for producing an alignment film, characterized in that an alignment film having an arbitrary alignment characteristic is obtained by irradiating a linearly polarized ultraviolet ray, and the structure of the photosensitive side-chain polymer is such that at least the chemical formula 1 And / or a structure represented by Chemical Formula 2;
A method for producing an alignment film, having a structure represented by Chemical Formulas 3 and 4, wherein the photosensitive side chain polymer is
A method for producing an alignment film, wherein the main chain is a homopolymer or a copolymer containing a structure selected from hydrocarbons, acrylates, methacrylates, and siloxanes, and a method for irradiating linearly polarized ultraviolet rays. A method for producing an alignment film, wherein the temperature of the side chain type polymer film is within a range of 10 ° C. or less from the transition temperature of the side chain type polymer to the isotropic phase. A method for producing an alignment film, comprising a step of heating and / or cooling the side chain type polymer film or its support, and an alignment film obtained by the method for producing an alignment film. A liquid crystal display device comprising the alignment film.

[0007]

The production method of the present invention (the alignment film) has the following specific effects. Depending on the irradiation time of the linearly polarized ultraviolet light and the copolymer composition (of the side chain)
The ability to freely control the orientation direction. as a result,
It is possible to obtain an alignment film in which any part of the alignment film is aligned with any alignment characteristics, and by combining such an alignment film with a liquid crystal display device, the pre-tilt angle of the liquid crystal,
The required characteristics can be improved. The alignment film of the present invention is formed by applying (spin coating) a polymer on a substrate,
By irradiating linearly polarized light (ultraviolet light) from a specific direction, it is possible to arrange the linearly polarized ultraviolet light irradiated on the side chain of the polymer in a direction parallel to the electric field oscillation direction and perpendicular to the irradiation light traveling direction. . By performing this irradiation in an oblique direction with respect to the substrate surface, the side chains of the polymer can be inclined and arranged. This inclination can be set in any direction by changing the direction of light irradiation. In addition, the dimer generated by the photoreaction can be oriented also in the direction perpendicular to the electric field vibration direction of the linearly polarized ultraviolet light. When the liquid crystal molecules come into contact with the polymer film thus aligned, the liquid crystal can be aligned by the interaction with the polymer side chain or the dimer of cinnamic acid group on the alignment film side.
Further, the tilt angle on the liquid crystal side can be controlled by tilting and aligning the side chains. FIG. 6 schematically shows this, in which the upper liquid crystal panel (61) and the lower alignment film (6) are formed.
At the interface (63) in contact with 2), the side chains (6
When 4) is oriented and tilted, the liquid crystal molecules (65) in the liquid crystal panel near the interface are tilted and oriented to the interface with a tilt angle α due to this effect.

When a plurality of regions having different electric field oscillation directions, irradiation directions and irradiation times of irradiation light are provided in the same alignment film by mask exposure, the alignment direction corresponding to the liquid crystal molecules in the liquid crystal panel near the interface is provided. A plurality of different areas can be set.
For example, FIG. 7 shows an enlarged view of a part of the alignment film (70) and a part of the substrate (75).
70b, 70c, 70d), linearly polarized ultraviolet rays (71a, 71) whose electric field oscillation directions differ by 90 degrees, respectively.
b, 71c, 71d), the side chains (not shown) in the respective regions are oriented in different directions. As a result, the liquid crystal molecules (72a, 7
2b, 72c, and 72d) exhibit different alignment states. FIG. 8 is an enlarged view of a part of the alignment film (80) and the substrate (85) similar to FIG. 7, and shows linearly polarized light having different irradiation angles with respect to two adjacent regions (80a, 80b). Irradiates the liquid crystal molecules (82a, 81b) in the liquid crystal panel in contact with the side chains in the two regions at different angles.
2b) shows a state where the liquid crystal molecules are oriented with different tilt angles β and γ. In a liquid crystal display device, if a liquid crystal in which the side chain of an adjacent arbitrary region in one pixel is aligned in an arbitrary alignment direction and angle can be obtained, a phase difference shift due to a direction in which the liquid crystal is viewed can be eliminated, and a viewing angle can be increased. Useful for

[0009]

Embodiments of the present invention will be described below. The homopolymer or copolymer of the present invention is biphenyl which is frequently used as a mesogen component of a liquid crystalline polymer,
Having a side chain including a structure in which a substituent such as terphenyl, phenylbenzoate, or azobenzene is bonded to a photosensitive group such as a cinnamic acid group (or a derivative group thereof);
It is a polymer having a main chain having a structure of a hydrocarbon, acrylate, methacrylate, siloxane or the like containing a certain proportion of a side chain containing a mesogen component to which no photosensitive group is bonded. These polymers are applied (spin-coated) on a substrate in the form of a solution and dried to form a polymer coating film.
This polymer coating film is non-oriented at the time of film formation, and the photosensitive side chain portion represented by the chemical formula 1 does not face a specific direction.
This state will be described with reference to FIG.
There is a photosensitive side chain (41) and a poorly photosensitive side chain (42) in the direction corresponding to the vibration direction of the irradiation polarized ultraviolet light having a photosensitive group represented by a long ellipse in a non-oriented state. I have.
When this coating film is irradiated with linearly-polarized ultraviolet light, a photosensitive group such as a cinnamic acid group (or a derivative thereof) disposed along the direction of electric field oscillation of the irradiated linearly-polarized light in the photosensitive side chain (41). Dimerization occurs most sensitively. In this dimerization reaction, cyclopropane bonds are formed linearly as shown in Reaction Formula 1, and are arranged in the direction perpendicular to the electric field direction of the irradiated linearly polarized light.

[0010]

Embedded image The rectangle described in Reaction Formula 1 is a molecular chain connecting the main chain of the polymer and the photosensitive group in the side chain type polymer liquid crystal, and includes a liquid crystal component and a bending component. To proceed with this dimerization reaction,
Irradiation of linearly polarized light having a wavelength at which the cinnamate group of the chemical formula 1 can react is required. This wavelength is represented by the formula -R
It varies depending on the type of ₁ ~-R _5, in general 200-50
0 nm, and in particular, the effectiveness of 250 to 400 nm is often high.

The orientation state of a coating film in which the dimerization reaction has not progressed after irradiation with ultraviolet rays will be described with reference to FIG.
In the coating film (50), the side chains (5
1) and dimerization occurs even if it does not have the photosensitive group represented by the chemical formula 2 or has the photosensitive group represented by the chemical formula 1 (because it is not arranged in the direction of the electric field of linearly polarized light). There are missing side chains (52). The dimerized side chains are oriented perpendicular to the direction of the applied linearly polarized electric field. In addition, the side chain (52) that did not undergo dimerization was also replaced by the dimerized side chain (5).
Orient in the same direction as in 1). As a result, in the entire polymer coating film, side chains are arranged in the direction of the electric field oscillation of the irradiated linearly polarized light. Next, when the dimerization reaction sufficiently proceeds after irradiation with ultraviolet rays, the dimer orientation becomes dominant over the side chain orientation. FIG. 10 shows a change in the alignment mode in such an alignment film with respect to the ultraviolet irradiation time. In the figure, when the irradiation time of ultraviolet rays is taken on the horizontal axis and the value ΔN representing the birefringence is taken on the vertical axis, ΔN
Increases monotonically, but ΔN starts decreasing around the irradiation time exceeding 100 seconds. This does not mean that the degree of orientation of the side chain is reduced, and the density of the dimer formed by the irradiation of the ultraviolet rays in the polymer film increases, and
This is due to a change in the orientation mode in which the orientation of the monomer becomes dominant.

The arrangement by the molecular motion is facilitated by heating the polymer (substrate to be coated) so that the molecule can easily move. The heating temperature is desirably lower than the softening point of the photoreacted portion (that is, the portion in which the orientation is fixed) and higher than the softening point of the side chain that has not been photoreacted and the side chain portion having no photosensitive group. For example, in the side chain (chemical formula 1), n = 6, m = 2, k = 6, and R _{1 to} R ₅ =
H, R ₆ = CN, X = none, Y = none, Z = CH ₃ in the main chain (formula 3), W = COO—, a:
In the example of b = 45: 55, 75-77 ° C. is appropriate.
In addition, the polymer coating film (substrate to be coated) is T _i ± 10 ° C.
Preferably T _i ± 5 ° C, more preferably T _i ± 2 ° C
(Here, Ti is a phase transition temperature when the phase changes from a liquid crystal phase to an isotropic phase.) The orientation can be promoted by irradiating polarized ultraviolet rays while heating. When the film irradiated with polarized light and then heated and the unreacted side chain is oriented or the film exposed and polarized under heating is cooled to a temperature below the softening point of the polymer, the molecules are frozen and the orientation of the molecules is reduced. A fixed alignment film is obtained. In addition, the side chain having no photosensitive group represented by the chemical formula 2 lowers the density of cross-linking points in the photodimerization reaction, improves the degree of freedom of molecular motion at the time of reorientation, and reorganizes due to its own molecular orientation. Promotes orientation. From such a viewpoint, chemical formula 3
Or in Formula 4, a: b = 100: 0 to 0:99
But a: b = 100: 0 to 30:70
Is more desirable.

A method for synthesizing a raw material compound of a polymer material will be described below. (Monomer 1) 4,4′-biphenyldiol and 2-chloroethanol were heated under alkaline conditions to synthesize 4-hydroxy-4′-hydroxyethoxybiphenyl. This product was reacted with 1,6-dibromohexane under alkaline conditions to obtain 4-
(6-Bromohexyloxy) -4′-hydroxyethoxybiphenyl was synthesized. Next, lithium methacrylate was reacted to give 4-hydroxyethoxy-4′-
(6′-biphenyloxyhexyl) methacrylate was synthesized. Finally, cinnamoyl chloride was added under basic conditions to synthesize a methacrylic ester represented by Chemical Formula 5.

Embedded image

(Monomer 2) 4-hydroxy-4'-cyanobiphenyl is reacted with 1,6-dibromohexane under alkaline conditions to give 4- (6-bromohexyloxy)-
4′-cyanobiphenyl was synthesized. Next, lithium methacrylate was reacted to obtain 4-cyano-4 ′-(6 ′).
-Biphenyloxyhexyl) methacrylate was synthesized. A methacrylic acid ester represented by Chemical Formula 6 was synthesized.

Embedded image

(Monomer 3) 4-Hydroxy-4'-hydroxyethoxybiphenyl was synthesized by heating 4,4'-biphenyldiol and 2-chlorohexanol under alkaline conditions. This product was reacted with 1,6-dibromohexane under alkaline conditions to obtain 4-
(6-Bromohexyloxy) -4′-hydroxyethoxybiphenyl was synthesized. Next, lithium methacrylate was reacted to give 4-hydroxyethoxy-4′-
(6′-biphenyloxyhexyl) methacrylate was synthesized. Finally, under basic conditions, 4-methoxycinnamoyl chloride was added to synthesize a methacrylate represented by the formula (7).

Embedded image

(Polymer 1) Polymer 1 is obtained by dissolving Monomer 1 in tetrahydrofuran, adding AIBN (azobisisobutyronitrile) as a reaction initiator and polymerizing.
I got This polymer 1 exhibited liquid crystallinity in a temperature range of 47 to 75 ° C.

(Polymer 2) Monomer 1 and Monomer 2 are dissolved in tetrahydrofuran at various ratios and polymerized by adding AIBN (azobisisobutyronitrile) as a reaction initiator and polymerizing. Merged 2 was obtained (a: b = 55: 4)
5). This polymer 2 exhibited liquid crystallinity in a temperature range of 44 to 95 ° C.

(Polymer 3) Monomer 1 and Monomer 2 are dissolved in tetrahydrofuran at various ratios, and polymerized by adding AIBN (azobisisobutyronitrile) as a reaction initiator and polymerizing. Merged 3 was obtained (a: b = 30: 7)
0). This polymer 3 exhibited liquid crystallinity in a temperature range of 45 to 101 ° C.

(Polymer 4) Polymer 4 is obtained by dissolving monomer 3 in tetrahydrofuran, adding AIBN (azobisisobutyronitrile) as a reaction initiator, and polymerizing.
I got This polymer 4 also exhibited liquid crystallinity.

[0020]

EXAMPLES The polymer material of the present invention exhibits a phase transition temperature by thermal analysis and a liquid crystal temperature range by observation with a polarizing microscope.
The birefringent optical pattern was confirmed to be a liquid crystal material. In Chemical Formulas 1 to 3, a: b =
55:45, n = 6, m = 2, k = 6, X, Y = none,
The thermal analysis curve of the polymer material of the present invention in which W = —COO—, R _{1 to} R ₅ = H, and R ₆ = —CN shows that 4
An endothermic peak was observed at 4 ° C, and an endothermic peak was also observed at 95 ° C.
It was a liquid crystalline material that exhibited a birefringent optical pattern in the temperature region when observed with a polarizing microscope. The side chain orientation of the polymer material by linearly polarized ultraviolet light irradiation is applied to the polymer coating film formed on the substrate by applying polarized ultraviolet light, and the direction parallel to the electric field oscillation direction of the irradiation light of the polymer coating film and the vertical direction. This was verified by comparing the polarized infrared spectra of. FIG. 9 shows a difference spectrum ΔA of polarized infrared light in a direction parallel to and perpendicular to the direction of the electric field oscillation of the irradiation light 30 seconds after the irradiation of the polarized light. The absorption of -CN, O-Ph, and Ph in the parallel direction was increased by the polarized light irradiation, and it was confirmed that the side chains were oriented in the direction of the electric field oscillation of the irradiated light. At this time, the birefringence of the polymer coating film is maximized, and further exposure reduces the birefringence as shown in FIG. This decrease in birefringence suggests that the cinnamoyl group formed a dimer and was oriented perpendicular to the electric field oscillation direction of linearly polarized light. FIG. 1 shows a method (apparatus) for producing an alignment film of the present invention. The disordered light (6) generated by the ultraviolet lamp (1) excited by the power supply (2) is converted into linearly polarized ultraviolet light (7) by the optical element (3) (for example, a Glan-Taylor prism), and is converted on the substrate (5). The resin film (4) applied (coated) is irradiated.

Example 1 Polymer 1 was dissolved in chloroform and spin-coated on an optically isotropic substrate to a thickness of about 100 nm. The resin film thus prepared was irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism at room temperature for 30 seconds. Next, using a mask pattern, linearly polarized light having the same electric field direction was irradiated for another 20 minutes except for the masked region. The substrate was heated to 150 ° C., cooled to 100 ° C., held for 10 minutes, and then cooled to room temperature. Using this substrate and a substrate of a normal alignment film, a liquid crystal cell sandwiching a liquid crystal E7 manufactured by Merck Japan K.K. was assembled. Observation of the liquid crystal cell under crossed Nicols and parallel Nicols revealed that the pattern matched with the mask pattern was inverted in brightness.

Example 2 Polymer 2 was dissolved in chloroform and spin-coated on an optically isotropic substrate to a thickness of about 100 nm. The resin film thus prepared was irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism at room temperature for 30 seconds. Next, using a mask pattern, linearly polarized light having the same electric field direction was irradiated for another 20 minutes except for the masked region. The substrate was heated to 150 ° C., cooled to 100 ° C., held for 10 minutes, and then cooled to room temperature. Using this substrate and a substrate of a normal alignment film, a liquid crystal cell sandwiching a liquid crystal E7 manufactured by Merck Japan K.K. was assembled. Observation of the liquid crystal cell under crossed Nicols and parallel Nicols revealed that the pattern matched with the mask pattern was inverted in brightness.

Example 3 The polymer 4 was dissolved in chloroform and spin-coated on an optically isotropic substrate to a thickness of about 100 nm. The resin film thus prepared was irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism at room temperature for 30 seconds. Next, using a mask pattern, linearly polarized light having the same electric field direction was irradiated for another 20 minutes except for the masked region. The substrate was heated to 150 ° C., cooled to 100 ° C., held for 10 minutes, and then cooled to room temperature. Using this substrate and a substrate of a normal alignment film, a liquid crystal cell sandwiching a liquid crystal E7 manufactured by Merck Japan Ltd. was assembled. Observation of the liquid crystal cell under crossed Nicols and parallel Nicols revealed that the pattern matched with the mask pattern was inverted in brightness.

Example 4 Polymer 1 was dissolved in chloroform and spin-coated on an optically isotropic substrate to a thickness of about 100 nm. The resin film thus adjusted was heated to 72 ° C., and irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism for 30 seconds. Next, using a mask pattern, linearly polarized light having the same electric field direction was irradiated for an additional 10 minutes except for the masked region. 150 substrates
After heating to 100 ° C, cooling to 100 ° C and holding for 10 minutes,
Cooled to room temperature. Using this substrate and a substrate of a normal alignment film, a liquid crystal cell sandwiching a liquid crystal E7 manufactured by Merck Japan K.K. was assembled. Observation of the liquid crystal cell under crossed Nicols and parallel Nicols revealed that the pattern matched with the mask pattern was inverted.

In each of Examples 1 to 4, since bright / dark inversion matching the mask pattern was observed, regions where the liquid crystal alignment directions of the respective regions were different from each other were formed on one alignment film (liquid crystal). It proves that they were formed at the same time.

Example 5 Polymer 1 was dissolved in chloroform and spin-coated to a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was arranged so as to be inclined by 30 degrees with respect to the horizontal plane, and irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism from the vertical direction at 72 ° C. for 30 seconds and cooled to room temperature. Using this substrate, a liquid crystal ZL manufactured by Merck Japan Ltd.
I2061 was coated, and the pretilt angle was measured by a crystal rotation method. The pretilt angle of the liquid crystal when using this substrate was 3.6 °. By manufacturing two such substrates and sandwiching the liquid crystal ZLI 2061,
A TN type liquid crystal cell having a thickness of 12 μm was assembled. The driving voltage of this TN type liquid crystal cell was 2V. It was confirmed that there was no alignment defect over the entire surface of the liquid crystal cell.

Example 6 Polymer 2 was dissolved in chloroform and spin-coated to a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was arranged so as to be inclined by 30 degrees with respect to the horizontal plane, and irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism from the direction perpendicular to the horizontal plane at an atmosphere temperature of 89 ° C. for 5 minutes and then cooled to room temperature. . Using this substrate, a liquid crystal ZLI 2061 manufactured by Merck Japan Ltd. was coated, and the pretilt angle was measured by a crystal rotation method. The pretilt angle of the liquid crystal when using this substrate was 4.2 °.

Example 7 The polymer 3 was dissolved in chloroform and spin-coated to a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was arranged so as to be inclined by 30 degrees with respect to the horizontal plane, and irradiated with ultraviolet light converted to linearly polarized light using a Glan-Taylor prism from the direction perpendicular to the horizontal plane at an atmosphere temperature of 89 ° C. for 5 minutes and then cooled to room temperature. . Using this substrate, a liquid crystal ZLI 2061 manufactured by Merck Japan Ltd. was coated, and the pretilt angle was measured by a crystal rotation method. The pretilt angle of the liquid crystal when using this substrate was 1.7 °.

[0029]

As described above, according to the present invention, an alignment film can be obtained by photoreaction, and this film can be applied to an alignment film for a liquid crystal display. In the alignment film, an alignment film that does not require alignment operation of liquid crystal molecules such as rubbing is prepared, so that defects generated in a process of assembling a liquid crystal display device are significantly reduced. In expanding the viewing angle of a liquid crystal display device, a technique is effective in which one pixel is divided to change the liquid crystal alignment direction, a low tilt angle and a high tilt angle alignment state is developed, and a tilt angle is inverted. It is. In the polymer material of the present invention, films having different orientation directions of liquid crystal molecules and different pretilt angles can be formed on the same substrate by changing the direction of electric field oscillation of irradiation light, the amount of light irradiation, and the irradiation direction. Orientation is also possible. Furthermore,
The alignment of liquid crystal molecules can be rotated by 90 ° by the amount of irradiation of linearly polarized light, and the alignment direction can be controlled in two directions with one mask pattern, so that no two mask patterns are required and no alignment is required. Can be. An alignment film having excellent heat resistance is obtained by photocrosslinking.

[0030]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a method for manufacturing an alignment film according to the present invention. FIG. 2 is a configuration diagram of a liquid crystal display device. FIG. 3 is an example showing a conventional method for manufacturing an alignment film. FIG. 4 is a schematic view of a side chain exposed by polarized light irradiation. FIG. 5 is a schematic diagram of side chains arranged by molecular motion after irradiation of polarized light. FIG. 6 is a schematic view of an alignment state of liquid crystal by the polymer material of the present invention. FIGS. 7 and 8 are schematic diagrams of liquid crystal alignment in which pixels are divided by the alignment film of the present invention.
FIG. 9 is a graph showing a measured infrared difference spectrum ΔA in a direction parallel to and perpendicular to the direction of electric field oscillation of irradiation light after irradiation of polarized light. FIG. 10 is a graph showing a change in a birefringence index according to a polarization irradiation time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultraviolet lamp 2 ... Power supply 3 ... Optical element (Gran Taylor prism) 4 ... Resin film 5 ... Substrate 6 ... Disordered light 7 ... Linearly polarized ultraviolet light 120 ... Liquid crystal display device 122: liquid crystal 123: polarizing plate 124: glass substrate 125: transparent electrode 126: alignment film

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08J 5/18 C08J 5/18

Claims (6)

[Claims] 1. A method for producing a polymer alignment film for accelerating the alignment of liquid crystal in a liquid crystal panel, comprising irradiating a photosensitive side-chain type polymer film with linearly polarized ultraviolet light to obtain an arbitrary alignment characteristic. What is claimed is: 1. A method for producing an alignment film, comprising: 2. The method for manufacturing an alignment film according to claim 1, wherein
As the structure of the photosensitive side chain type polymer, the side chain includes at least the structure represented by Chemical Formula 1 and / or Chemical Formula 2, and has a structure represented by Chemical Formula 3 or Chemical Formula 4. A method for manufacturing an alignment film. Embedded image Embedded image Embedded image Embedded image However, in Chemical Formulas 1 to 4, n, m, k = 1 to
12, a: b = 100: 0 to 1:99 R _{1 to} R ₆ = -H, -CN, -C = C-, -C = C (C
N) ₂ , —C ＝ CH—CN, an alkyloxy group such as a halogen group or a methoxy group, X, Y = none, —COO,
-OCO -, - N = N - , - C = C -, - C 6 H 4 -,
_{Z = -H, -CH 3, -C} 2 H 5, -C 3 H 7, halogen, W = none, -COO, -OCO -, - (O-
CH ₂₎ -. 3. The method for producing an alignment film according to claim 1, wherein the temperature of the photosensitive side chain type polymer film when irradiating linearly polarized ultraviolet light is changed to the isotropic phase of the side chain type polymer. Characterized in that the difference from the transition temperature is within 10 ° C. 4. The method for producing an alignment film according to claim 1, further comprising a step of heating and / or cooling the photosensitive side chain type polymer film or its support. . 5. An alignment film obtained by the method for producing an alignment film according to claim 1. 6. A liquid crystal display device comprising the alignment film according to claim 5.