JP6584753B2 - Alignment film forming composition, alignment film forming method, and liquid crystal display device - Google Patents

Description

  The present invention relates to a composition for forming an alignment film, a method for forming an alignment film, and a liquid crystal display device.

Since liquid crystal display devices have characteristics such as low drive voltage, low power consumption, and light weight, they are used not only for clock display panels and mobile phone displays, but also for computers and television displays. .
In current mainstream liquid crystal display devices, driving methods such as a TN (twisted nematic) mode, a VA (vertical alignment) mode, and an IPS (in-plane switching) mode are employed. In any of these drive-type liquid crystal display devices, means for controlling the alignment of liquid crystal molecules is required, and means for forming an alignment film is generally used. For example, in a TN or IPS mode liquid crystal display device, alignment of liquid crystal molecules is controlled in a direction parallel to the substrate by an alignment film subjected to rubbing treatment. On the other hand, in a VA mode liquid crystal display device that does not require rubbing, the alignment of liquid crystal molecules is controlled in a direction perpendicular to the substrate by an alignment film.

As the alignment film, a polyimide film is generally used from the viewpoint of various properties such as alignment performance and heat resistance. This polyimide film is generally formed using a method in which a solution containing a polyimide precursor such as polyamic acid is applied to a substrate and imidized on the substrate, or a method in which a solution of soluble polyimide is applied to the substrate (for example, Patent Documents 1 and 2).
However, in the method using a solution containing a polyimide precursor, a high-temperature treatment (generally 250 ° C. or more, specifically 300 to 350 ° C.) is required to imidize the polyimide precursor. In addition, there is a problem that it is difficult to control physical properties. Further, it is necessary to use an expensive substrate having high heat resistance that can withstand high-temperature processing (for example, a glass substrate or a heat-resistant plastic substrate), and there is a problem that the manufacturing cost of the liquid crystal display device increases.

On the other hand, in the method using a solution of a soluble polyimide, an alignment film can be formed at a low temperature treatment as compared with a method using a solution containing a polyimide precursor. However, a soluble polyimide has a low solubility in a solvent. There is a problem of increased usage. In particular, since the solvent used for the soluble polyimide solution is an expensive high-boiling solvent such as N-methylpyrrolidone or γ-butyllactone, there is a problem that the cost for forming the alignment film increases.
The solubility of soluble polyimide in solvents can be improved by introducing functional groups such as alicyclic skeletons into the soluble polyimide to reduce symmetry, but the solubility of soluble polyimides previously proposed in solvents has been improved. Is about 6% at the maximum, which is not enough.

Japanese Patent No. 3150953 Japanese Patent No. 3289271

  The present invention has been made to solve the above-described problems, and can reduce the amount of solvent used, and can form an alignment film by low-temperature treatment using an inexpensive low-boiling solvent. An object is to provide a composition for forming an alignment film, a method for forming the alignment film, and a liquid crystal display device using the composition.

As a result of intensive studies to solve the above problems, the present inventors have found that the polymer having a dendron side chain is excellent in the solubility in various solvents and the alignment performance of liquid crystal molecules. As a result, it was found that the use amount of the solvent can be reduced and an alignment film having the same characteristics as the polyimide film can be easily formed by low-temperature treatment, and the present invention has been completed.
That is, this invention is a composition for alignment film formation characterized by including the polymer which has a dendron side chain.
Moreover, this invention is a formation method of the alignment film characterized by forming an alignment film by applying the said composition for alignment film formation on a board | substrate, and then making it dry.
Furthermore, the present invention provides a liquid crystal display device having a pair of substrates on which an alignment film is formed and a liquid crystal layer sandwiched between the pair of substrates, wherein the alignment film is the composition for forming an alignment film It is a liquid crystal display device characterized by being formed using.

  According to the present invention, the composition for forming an alignment film and a method for forming the alignment film, which can reduce the amount of solvent used and can form an alignment film by low-temperature treatment using an inexpensive low-boiling solvent, In addition, it is possible to provide a liquid crystal display device using the same.

It is sectional drawing of the VA mode liquid crystal display device of Embodiment 3 using the planar electrode in the case of (A) electric field OFF and (B) electric field ON. It is sectional drawing of the VA mode liquid crystal display device of Embodiment 3 using the comb-shaped electrode in the case of (A) electric field OFF and (B) electric field ON.

Embodiment 1 FIG.
The alignment film forming composition of the present embodiment is characterized by containing a polymer having a dendron side chain.
As used herein, “dendron side chain” means a regularly branched dendritic side chain, and “alignment film” means a film that controls the alignment state of liquid crystal molecules. To do.

Since the polymer having a dendron side chain is excellent in solubility in various solvents, the amount of the solvent used in the composition for forming the alignment film can be reduced and the solvent is less expensive than the high-boiling solvent. A low boiling point solvent can be used. Therefore, the cost of the composition for forming an alignment film can be reduced from the viewpoint of the type and amount of the solvent used in the composition for forming an alignment film. In addition, by using a low boiling point solvent as a solvent used in the composition for forming an alignment film, an alignment film can be formed by a low-temperature treatment, and the degree of freedom in selecting a substrate used in a liquid crystal display device is increased.
Here, in the present specification, the “low boiling point solvent” means a solvent having a boiling point of 150 ° C. or less, preferably 120 ° C. or less, more preferably 25 ° C. to 100 ° C.

  The low boiling point solvent is not particularly limited as long as it can dissolve a polymer having a dendron side chain and has a boiling point within a predetermined range, and those known in the art can be used. Examples of low boiling point solvents include polar aprotic solvents such as tetrahydrofuran (THF), acetone and acetonitrile; nonpolar solvents such as hexane, benzene, toluene, diethyl ether, chloroform, ethyl acetate and methylene chloride; acetic acid, 1- Examples include polar protic solvents such as butanol, 1-propanol, 2-propanol, ethanol, and methanol. These can be used alone or in combination of two or more. Among these, tetrahydrofuran is preferable from the viewpoints of stability and workability of the alignment film forming composition.

  A polymer having a dendron side chain is excellent in the alignment performance of liquid crystal molecules like polyimide, and an alignment film having the same characteristics as a polyimide film is formed by using an alignment film forming composition containing this polymer. can do. Therefore, the film formed from the composition for forming an alignment film containing a polymer having a dendron side chain gives the same effect as an alignment film such as a conventional polyimide film, and the liquid crystal molecules in the liquid crystal layer are attached to the substrate. It can be oriented in the vertical direction.

  The type of the main chain polymer constituting the polymer having a dendron side chain is not particularly limited, and various polymers known in the art can be used. Examples of the polymer include acrylic polymer, polystyrene polymer, polyolefin polymer, epoxy polymer, polyester polymer, polyamide polymer, polyurethane polymer and the like. Among these, acrylic polymers are preferable from the viewpoint of heat resistance and the ability to control alignment of liquid crystal molecules.

  Although it does not specifically limit as a dendron side chain, From a soluble viewpoint with respect to various solvents, what has at least 1 selected from the group which consists of an alkyl group, an alkoxy group, and a fluorine at a terminal is preferable. If it is a dendron side chain which has such a structure, the solubility with respect to various solvents is especially excellent.

  The dendron side chain preferably has a mesogenic group from the viewpoint of the alignment control ability of liquid crystal molecules. If it is a dendron side chain which has such a structure, it will be hard to inhibit the characteristic of a liquid-crystal component, and it is excellent also in liquid-crystal orientation control. Here, in the present specification, the “mesogenic group” means an organic group having a rigid structure necessary for exhibiting liquid crystallinity. The mesogenic group is not particularly limited. Biphenyl cyclohexyl, phenoxyphenyl, benzylidene aniline, benzyl benzoate, phenyl pyrimidine, phenyl dioxane, benzoyl aniline, tolan and derivatives thereof may be mentioned.

  The generation of the dendron side chain (the order of branching) is not particularly limited, but generally those of the first to sixth generations can be used. Here, one having the number of branches in this specification is referred to as a first generation.

  The number average molecular weight of the polymer having a dendron side chain is not particularly limited, but is preferably 2500 to 30000, more preferably 3000 to 22000, and still more preferably 4000 to 15000. Here, the “number average molecular weight” in this specification means a molecular weight measured by gel permeation chromatography (GPC) using polystyrene as a standard.

  A polymer preferable for use in the composition for forming an alignment film of the present embodiment is an acrylic polymer represented by the following general formula (1).

In general formula (1), n is a positive number of 2 to 20, preferably a positive number of 2 to 15, more preferably a positive number of 3 to 10, and D is a dendron side chain.
The dendron side chain D is represented by the following general formula (2).

  In the general formula (2), a and b are integers of 2 to 5, preferably an integer of 2 to 4, more preferably an integer of 2 to 3, and R is represented by the following general formula (3).

  In general formula (3), c is an integer of 3 to 12, preferably an integer of 4 to 10, more preferably an integer of 5 to 8, and A is

It is. In the formula, R ¹ is an alkyl group or an alkoxy group having 1 to 12 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, or fluorine.

  A polymer having a dendron side chain can be prepared by homopolymerizing a monomer having a dendron side chain. Therefore, a monomer capable of homopolymerization may be selected according to the type of polymer to be prepared. For example, the acrylic polymer represented by the above general formula (1) can be prepared by homopolymerizing an acrylic monomer represented by the following general formula (4).

In general formula (4), D is as defined in general formula (1) above.
In general, a monomer having a dendron side chain can be prepared by previously synthesizing a dendron and then introducing the dendron into the side chain of the monomer.
The method for synthesizing the dendron is not particularly limited, and can be performed using a known method. In general, a dendron can be synthesized by reacting a compound that gives a focal point (center) with a compound that binds to this compound and gives a branch part of a dendron. For example, an acrylate derivative that gives a dendron branch and a compound having a terminal amino group that reacts with the acrylate derivative may be reacted in an organic solvent.

The compound giving a focal point is not particularly limited, and may be appropriately selected according to the dendron to be synthesized. When adjusting the generation of dendron (branch order), a branched structure may be formed by reacting a compound giving a focal point with acrylonitrile or the like.
For example, when synthesizing an acrylic monomer of the general formula (4), after synthesizing a dendron represented by the following general formula (5), the dendron is introduced into the side chain of the acrylic monomer.

In the general formula (5), a, b and R are as defined in the above general formula (2).
When synthesizing the dendron of the general formula (5), a compound having the following general formula (6) is used as a compound giving a focal point, and a compound having the following general formula (7) is used as a compound giving a branch part of a dendron, respectively. be able to.

In general formulas (6) and (7), a, b, c and A are as defined in general formulas (2) and (3) above.
The reaction ratio of a compound that gives a focal point (for example, a compound of general formula (6)) to a compound that gives a branch part of a dendron (for example, a compound of general formula (7)) depends on the type of the compound used. Although it is necessary to adjust appropriately, in general, 1 to 10 moles of a compound that gives a dendron branch part may be used per 1 mole of a compound that gives a focal point.

It does not specifically limit as an organic solvent used for said reaction, A well-known thing can be used in the said technical field. Examples of organic solvents include halogenated hydrocarbon solvents such as 1,2-dichloroethane and chloroform; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; toluene, Aromatic hydrocarbon solvents such as xylene; aprotic polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, and N, N-dimethylacetamide. These organic solvents can be used individually or in mixture of 2 or more types.
Further, the amount of the organic solvent may be appropriately adjusted according to the kind and amount of the raw material to be used, and is not particularly limited.

The reaction temperature is −50 to 150 ° C., preferably 25 to 80 ° C. When the reaction temperature is lower than −50 ° C., the reaction rate may be significantly reduced. Moreover, when reaction temperature exceeds 150 degreeC, stability of a raw material may fall.
The reaction time is 2 to 200 hours, preferably 48 to 100 hours. If the reaction time is less than 2 hours, the reaction may not proceed sufficiently. If the reaction time exceeds 200 hours, it takes too much time and is not practical.
After completion of the reaction, the desired dendron can be obtained by removing the solvent. Alternatively, the dendron may be purified by adding a poor solvent such as methanol, ethanol, isopropyl alcohol, hexane, or toluene and heating to remove the supernatant.

  The dendron represented by the general formula (5) can be synthesized with an acrylic monomer of the general formula (4) by esterification with an acrylate in the presence of a base such as triethylamine or pyridine. . At this time, if necessary, a solvent such as tetrahydrofuran (THF) can be used. Since this esterification reaction is generally known in the technical field, the conditions may be adjusted according to a known method.

The method for homopolymerizing the monomer having a dendron side chain is not particularly limited, and may be appropriately selected according to the type of monomer used. Since the homopolymerization of a monomer is generally known in the technical field, the conditions may be adjusted according to a known method.
For example, when the acrylic monomer of the general formula (1) is obtained by homopolymerizing the acrylic monomer of the general formula (4), the acrylic monomer of the general formula (4) is homopolymerized using a polymerization initiator such as AIBN. Good. At this time, if necessary, a solvent such as tetrahydrofuran (THF) can be used. Since this polymerization reaction is generally known in the technical field, the conditions may be adjusted according to a known method.

  Although content of the polymer which has a dendron side chain in the composition for alignment film formation of this Embodiment is not specifically limited, It can make more than content of the soluble polyimide in the solution of the conventional soluble polyimide. Specifically, the content of the polymer having a dendron side chain in the alignment film forming composition of the present embodiment is preferably more than 6% by mass and 50% by mass or less, more preferably 8 to 45% by mass, and still more preferably. Is 10-40 mass%. By setting it as such content, the composition for alignment film formation of this Embodiment can increase content of the alignment film formation component (solid content) compared with the solution of the conventional soluble polyimide. Therefore, the amount of the alignment film forming composition used can be reduced, and the storage container for the alignment film forming composition can be made small.

Embodiment 2. FIG.
The alignment film forming method of the present embodiment is characterized in that the alignment film is formed by applying the above-described alignment film forming composition onto a substrate and then drying it.
Since the alignment film-forming composition does not contain a precursor, this alignment film forming method does not require a high-temperature treatment process (post-baking process) that causes an imidization reaction or the like. Therefore, the method for forming an alignment film according to the present embodiment can be easily performed by simply drying the applied material of the alignment film forming composition, and the alignment film forming process can be shortened. In addition, since a high-temperature treatment process is not required, various base materials such as general-purpose plastic base materials can be used, and the degree of freedom in selecting a substrate used in a liquid crystal display device is increased.
The drying temperature is not particularly limited as long as the solvent can be removed from the alignment film-forming composition, but is preferably 200 ° C. or less, more preferably 40 to 150 ° C., and even more preferably 50 to 100 ° C. It is.

  It does not specifically limit as a coating method of the composition for alignment film formation, A well-known method can be used in the said technical field. Examples of the coating method include screen printing method, offset printing method, flexographic printing method, ink jet printing method, dip coating method, roll coater coating method, spin coating method and the like.

Embodiment 3 FIG.
The liquid crystal display device of the present embodiment is a liquid crystal display device having a pair of substrates on which an alignment film is formed and a liquid crystal layer sandwiched between the pair of substrates, and the alignment film is the alignment film described above It is formed using the composition for formation.
Hereinafter, the liquid crystal display device of the present embodiment will be described in detail with reference to the drawings. Note that the liquid crystal display device of the present embodiment can adopt the configuration of a known liquid crystal display device other than the configuration of the alignment film, and is not limited to the following configuration.

FIG. 1 is a cross-sectional view of a VA mode liquid crystal display device of the present embodiment using a planar electrode. 1A shows a case where the electric field is OFF, and FIG. 1B shows a case where the electric field is ON. This VA mode liquid crystal display device includes a pair of opposed substrates 1a and 1b such as glass substrates, and a liquid crystal layer 2 formed between the substrate 1a and the substrate 1b, and the liquid crystal layers of the substrates 1a and 1b. An alignment film 8 for controlling the alignment of liquid crystal molecules is formed on the surface in direct contact with 2. In addition, a color filter layer 4 for realizing a desired color, an overcoat layer 5 for protecting the color filter layer 4 and a planar electrode 6 are sequentially formed on the substrate 1a. A planar electrode 6 is formed. The liquid crystal layer 2 is sealed with a sealing material 9.
In this VA mode liquid crystal display device, the alignment film 8 formed by using the alignment film forming composition can align the liquid crystal molecules 3 in the liquid crystal layer 2 perpendicularly to the substrate. Therefore, in this VA mode liquid crystal display device, when (A) the electric field is OFF, the liquid crystal molecules (n-type liquid crystal molecules) 3 in the liquid crystal layer 2 are aligned perpendicular to the substrates 1a and 1b, and (B) the electric field is ON. In this case, the liquid crystal molecules (n-type liquid crystal molecules) 3 can be aligned perpendicular to the lines of electric force (arrows in the figure), that is, aligned parallel to the substrates 1a and 1b.

FIG. 2 is a cross-sectional view of the VA mode liquid crystal display device of the present embodiment using comb electrodes. 2A shows the case where the electric field is OFF, and FIG. 2B shows the case where the electric field is ON. The liquid crystal display device includes a pair of opposed substrates 1a and 1b such as glass substrates, and a liquid crystal layer 2 formed between the substrates 1a and 1b, and the liquid crystal layer 2 of the substrates 1a and 1b. An alignment film 8 for controlling the alignment of liquid crystal molecules is formed on the directly contacting surface. Further, a color filter layer 4 for realizing a desired color and an overcoat layer 5 for protecting the color filter layer 4 are sequentially formed on the substrate 1a, and the comb electrode 7 is formed on the substrate 1b. Is formed. The liquid crystal layer 2 is sealed with a sealing material 9. Note that an FFS (fringe field switching) mode (see, for example, Japanese Patent Application Laid-Open No. 2008-51846) can be used for the comb electrode structure.
In this VA mode liquid crystal display device, the alignment film 8 formed by using the alignment film forming composition can align the liquid crystal molecules 3 in the liquid crystal layer 2 perpendicularly to the substrate. Therefore, in this VA mode liquid crystal display device, when (A) the electric field is OFF, the liquid crystal molecules (p-type liquid crystal molecules) 3 in the liquid crystal layer 2 are aligned perpendicular to the substrates 1a and 1b, and (B) the electric field is ON. In this case, the liquid crystal molecules (p-type liquid crystal molecules) 3 can be aligned parallel to the lines of electric force (arrows in the figure), that is, aligned parallel to the substrates 1a and 1b.

EXAMPLES Hereinafter, although an Example demonstrates the detail of this invention, this invention is not limited by these.
First, a dendron represented by the above general formula (5) (a = 2, b = 3, R is represented below) was synthesized as follows.

<Synthesis of 2- [N, N-bis (2-cyanoethyl) amino] ethanol>
A 200 mL eggplant flask is charged with water (60 mL), 2-aminoethanol (10 g, 0.17 mmol) and acrylonitrile (22 g, 0.42 mol), and stirred at 80 ° C. for 1 hour, and then acrylonitrile and water are added under reduced pressure. Distilled off. Next, the residue was dissolved in chloroform, water was removed by adding anhydrous magnesium sulfate to this solution, and then chloroform was removed under reduced pressure to obtain a colorless transparent liquid in a yield of 27 g (yield 97%). . When IR of this liquid was measured, characteristic absorption of 3492 cm ⁻¹ (OH) and 2248 cm ⁻¹ (CN) was observed.

<Synthesis of 2- [N, N-bis (3-aminopropyl) amino] ethanol>
A 300 mL three-necked flask was charged with lithium aluminum hydride (6.9 g, 0.18 mol) and THF (160 mL), and stirred at room temperature for 30 minutes. Next, concentrated sulfuric acid (3.6 mL, 0.068 mol) was added to the solution at −5 ° C., and the mixture was further stirred for 1 hour. Next, a THF solution (30 mL) of 2- [N, N-bis (2-cyanoethyl) amino] ethanol (5.0 g, 0.03 mol) was added to this solution, and the mixture was further stirred at room temperature for 8 hours. Next, water (9.7 mL) was added to the mixed solution using a syringe in an ice bath. After separating the produced solid by filtration, the solid was Soxhlet extracted with methanol for 24 hours. Next, after the extract and the filtrate separated by filtration were mixed, anhydrous magnesium sulfate was added to this solution to remove moisture. Next, the solvent was removed under reduced pressure to obtain a yellow liquid in a yield of 2.9 g (yield 54%). When IR of this liquid was measured, characteristic absorption of 3285 cm ⁻¹ (OH) was observed.

<Synthesis of dendron>
In a 50 mL eggplant flask, 2- [N, N-bis (3-aminopropyl) amino] ethanol (0.18 g, 1.0 mmol), 6- [4- (trans-4-pentylcyclohexyl) phenoxy] hexyl acrylate (2.1 g, 5.1 mmol) and THF (1.0 mL) were added and stirred for 3 days under a nitrogen atmosphere. Next, after removing THF under reduced pressure, the residue was dissolved in chloroform, and this solution was washed three times with water. Next, anhydrous magnesium sulfate was added to this solution to remove moisture, and then chloroform was removed under reduced pressure. Next, after the residue was dissolved in a small amount of chloroform, this solution was added to 100 mL of methanol, and the supernatant was removed by decantation to collect the precipitate. Purification was carried out by repeating this operation 6 times to obtain a pale yellow solid in a yield of 0.85 g (49% yield).

When ¹ H-NMR (CDCl ₃ , 400 MHz) of this pale yellow solid was measured, 7.12 to 6.79 ppm (m, ArH, 16H), 4.07 ppm (t, COOCH ₂ , 8H), 3.91 ppm Characteristic absorption of (t, PhOCH ₂ , 2H), 3.53 ppm (t, HOCH ₂ , 2H) was observed. Moreover, when the molecular weight of this pale yellow solid was measured by MALDI-TOF-MS, it was an actually measured value m / Z = 1778.27 (M + H) with respect to the theoretical value m / Z = 1777.37 (M + H). Further, when DSC measurement of this pale yellow solid was performed, endothermic peaks were observed at 14 ° C. and 63 ° C. during the temperature rising process, and exothermic peaks were observed at 19 ° C. and 58 ° C. during the temperature lowering process.

<Synthesis of an acrylic monomer having a dendron side chain>
An acrylic monomer represented by the above general formula (4) (a, b and R are as shown in the above-mentioned dendron synthesis) was synthesized as follows.
Triethylamine (23.5 μL, 0.169 mmol) was added to a THF (4.0 mL) solution of the dendron (0.202 g, 0.114 mmol) obtained above, and the mixture was stirred at room temperature for 30 minutes. Next, while cooling in a water bath, acrylic acid chloride (27.5 μL, 0.340 mmol) was added dropwise, and the reaction was allowed to stir at room temperature for 3 days. The reaction was then concentrated under reduced pressure, and the concentrate was dissolved in chloroform. The solution was washed twice with saturated aqueous sodium bicarbonate (20 mL), three times with water (20 mL) and 2 times with saturated brine (20 mL). Washed twice. Next, anhydrous magnesium sulfate was added to this solution to remove moisture, followed by filtration, and the filtrate was concentrated under reduced pressure. Next, the residue was purified by GPC (solvent: chloroform), and a yellow viscous liquid (acrylic monomer) was obtained in a yield of 98 mg (0.054 mmol, yield 47%).

When ¹ H-NMR (CDCl ₃ , 400 MHz) of this liquid (acrylic monomer) was measured, 7.12 to 6.81 ppm (m, Ph, 16H), 6.41 ppm (d, CH ₂ ═CH—, 1H) ), 6.14 ppm (dd, CH ₂ ═CH—, 1H), 5.81 ppm (d, CH ₂ ═CH—, 1H), 4.21 ppm (s, —OCH ₂ CH ₂ N—, 2H), 4 A characteristic absorption of 0.07 ppm (t, —OCH ₂ —, 8H), 3.92 ppm (t, —CH ₂ OPh—, 8H), 2.79 to 0.89 ppm (m) was observed.

<Synthesis of acrylic polymer having dendron side chain>
The acrylic polymer represented by the above general formula (1) (a, b and R are as shown in the above-mentioned synthesis of dendron and n is 4.2) was synthesized as follows.
AIBN (0.8 mg, 4.9 μmol) was added to a THF (0.4 mL) solution of the acrylic monomer having a dendron side chain (78 mg, 43 μmol) obtained above, and the mixture was stirred at 60 ° C. for 12 hours under a nitrogen atmosphere. And reacted. Next, after the reaction product was concentrated under reduced pressure, the residue was purified by GPC (solvent: chloroform) to obtain a brown solid (acrylic polymer) in a yield of 19 mg (yield 24%).

When the number average molecular weight of this solid (acrylic polymer) was measured using GPC, it was 7,700.
Further, this solid was measured by ¹ _H-NMR (acrylic polymer) (CDCl 3, 400MHz), 7.09~6.79ppm (m, Ph), 4.03ppm (m), 3.89ppm (m) A characteristic absorption of 2.75 to 0.79 ppm (m) was observed.

About the acrylic polymer which has the dendron side chain synthesize | combined above, the solubility (25 degreeC) test with respect to tetrahydrofuran (THF) was done.
As a result, it was visually confirmed that the acrylic polymer having a dendron side chain synthesized above was completely dissolved in THF up to 29% by mass.

Next, a liquid crystal cell was prepared using a tetrahydrofuran solution (composition for forming an alignment film) containing 10% by mass of an acrylic polymer having a dendron side chain synthesized above.
First, a chrome comb-shaped electrode (Eetchy Co., Ltd., interelectrode distance: 10 μm, electrode area: 2 cm ² ) was formed on one glass substrate, and then an alignment film forming composition was applied by spin coating, followed by 80 ° C. Then, an alignment film was formed by drying. In addition, the alignment film forming composition was formed on the other glass substrate by applying the composition for forming an alignment film by spin coating and drying at 80 ° C. Next, a dot-like column spacer (manufactured by JSR Corporation, model number JNPC-123-V2, height of about 5 μm) is arranged on one glass substrate on which the alignment film is formed, and a glass substrate excluding a portion serving as an inlet area After applying a thermosetting sealing material (model number XN21-S, manufactured by Mitsui Chemicals, Inc.) to the periphery of the substrate, it is overlapped with the other glass substrate on which the alignment film is formed, and 5 at 160 ° C. in a spring-type jig pressurizing environment. The glass substrates were bonded together by heating for a period of time. Next, after fluorinated mixed liquid crystal (ZLI 4972 manufactured by Merck Japan) was injected from the injection port with a capillary, the injection port was sealed with a UV adhesive (manufactured by ThreeBond, model number 3027D). The cell gap of the liquid crystal cell thus obtained was about 3.0 μm.

About the produced liquid crystal cell, the switching characteristic before the temperature raising / lowering process and after the temperature raising / lowering process was evaluated. This evaluation was performed by observing the behavior when an electric field was applied and when no electric field was applied, using a polarizing microscope (BX-50p, manufactured by Olympus Corporation). In the temperature raising / lowering process, the liquid crystal cell is placed on a hot stage (microscope heating / cooling device LK-600PM, manufactured by Linkham Co., Ltd.), and the temperature is raised from 20 ° C. to 120 ° C. at a temperature raising rate of 20 ° C./min. Then, it was cooled to 20 ° C. at a cooling rate of 1 ° C./min.
As a result of this evaluation, in the liquid crystal cell having the alignment film formed using the alignment film forming composition containing a polymer having a dendron side chain, both before and after the temperature increasing / decreasing process It was confirmed that uniform vertical alignment was confirmed, switching from dark field to bright field was good, and switching characteristics were excellent.

  As can be seen from the above results, according to the present invention, the composition for forming an alignment film can reduce the amount of solvent used and can form an alignment film by low-temperature treatment using an inexpensive low-boiling solvent. It is possible to provide a method for forming an object and an alignment film, and a liquid crystal display device using the same.

  1a, 1b substrate, 2 liquid crystal layer, 3 liquid crystal molecule, 4 color filter layer, 5 overcoat layer, 6 planar electrode, 7 comb electrode, 8 alignment film, 9 sealing material.

Claims (13)

An alignment film forming composition comprising a polymer having a dendron side chain, wherein the polymer is an acrylic polymer,
The acrylic polymer has the following general formula (1):

(Wherein n is a positive number from 2 to 20, and D is a dendron side chain),
The dendron side chain D is represented by the following general formula (2):

(In the formula, a and b are integers of 2 to 5, and R is the following general formula (3):


(In the formula, c is an integer of 3 to 12, and A is

(Wherein R1 is an alkyl group or alkoxy group having 1 to 12 carbon atoms, or fluorine)).
An alignment film forming composition characterized by the above.   The composition for forming an alignment film according to claim 1, wherein the dendron side chain has at least one selected from the group consisting of an alkyl group, an alkoxy group, and fluorine at the terminal. The composition for forming an alignment film according to claim 1, wherein the dendron side chain has a mesogenic group .   Content of the said polymer is 6 mass% excess 50 mass% or less, The composition for alignment film formation as described in any one of Claims 1-3 characterized by the above-mentioned.   5. The composition for forming an alignment film according to claim 1, further comprising a low-boiling solvent that dissolves the polymer and has a boiling point of 150 ° C. or less.   The composition for forming an alignment film according to claim 5, wherein the low boiling point solvent is tetrahydrofuran.   A method for forming an alignment film, wherein the alignment film is formed by applying the composition for forming an alignment film according to claim 1 onto a substrate and then drying the composition. A first substrate and a second substrate facing each other;
A liquid crystal layer sandwiched between the first substrate and the second substrate;
A first alignment film sandwiched between the first substrate and the liquid crystal layer;
A second alignment film sandwiched between the second substrate and the liquid crystal layer;
A liquid crystal display device comprising:
Each of said 1st alignment film and 2nd alignment film is formed using the composition for alignment film formation as described in any one of Claims 1-6, The liquid crystal display device characterized by the above-mentioned. . A first electrode sandwiched between the first substrate and the first alignment film;
A second electrode sandwiched between the second substrate and the second alignment film;
The liquid crystal display device according to claim 8, further comprising: A color filter layer sandwiched between the first substrate and the first electrode;
An overcoat layer sandwiched between the color filter layer and the first electrode;
The liquid crystal display device according to claim 9, further comprising:   The liquid crystal display device according to claim 8, further comprising a comb electrode sandwiched between the second substrate and the second alignment film. A color filter layer sandwiched between the first substrate and the first alignment film;
An overcoat layer sandwiched between the color filter layer and the first alignment film;
The liquid crystal display device according to claim 11, further comprising: The liquid crystal molecules in the liquid crystal layer are aligned perpendicular to the surfaces of the first substrate and the second substrate in a state where an electric field is not applied,
The liquid crystal molecules in the liquid crystal layer are aligned parallel to the surfaces of the first substrate and the second substrate in a state where an electric field is applied.
The liquid crystal display device according to claim 8, wherein the liquid crystal display device is a liquid crystal display device.