JP3427464B2 - New polyester imide - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel polyesterimide.

[0002]

2. Description of the Related Art Polyimide resin is an excellent plastic that has the highest heat resistance among commercially available plastics, has little change in characteristics with temperature, and has good impact resistance, dimensional stability, electrical characteristics, and abrasion resistance. . Utilizing these characteristics, it is used as a material for aerospace and machinery, including electrical and electronic fields such as insulation and sealing materials and printed circuit boards. Further, in recent years, attention has been paid as a material for an alignment film of a liquid crystal display element, and many polyimide-based alignment films have been developed.

In a liquid crystal display element used in a clock or a calculator, a twisted nematic (hereinafter referred to as TN) having a structure in which the arrangement direction of nematic liquid crystal molecules is twisted by 90 degrees or more between a pair of upper and lower electrode substrates. The mode is mainly adopted. The alignment film used in such a liquid crystal display device is not enough to simply arrange the liquid crystal molecules, and in order to improve the responsiveness and ensure the bistability, the alignment film is formed between the substrate surface and the liquid crystal molecules. It must have a pretilt angle of ~ 4 degrees.

Further, when the same scene is turned on for a long time in the liquid crystal display device, a phenomenon in which the previous image remains as an afterimage may be seen even after turning off the scene. The cause of the afterimage is that a direct current (DC) component is applied to the liquid crystal element, so that an electric double layer is generated on the surface of the alignment film due to an ionic component of impurities contained in the liquid crystal, and a bias of electrification occurs between the upper and lower substrates. It is considered that this is caused by the potential difference caused by the occurrence of the above-mentioned phenomenon and stabilization of the bias. In particular, in a thin film transistor element (TFT element) which is an active element, since the DC component cannot be removed due to the characteristics of the element, the afterimage phenomenon is more conspicuous and serious than the TN element. Therefore, the alignment film used in these liquid crystal cells must have good electric characteristics without the afterimage phenomenon.

Japanese Unexamined Patent Publication No. 61-240223 discloses a formula [4].

[Chemical 10] (However, Ar represents a tetravalent aromatic group.) A polyimide resin having a structural unit represented by the formula and a liquid crystal alignment film using the same are disclosed. However, this polyimide alignment film has a drawback that an afterimage phenomenon occurs.

Further, JP-A-5-214101 discloses a polyesterimide using bis [4- (dicarboxybenzoyloxy) phenylalkyl] dianhydride as a monomer. However, when this polyester imide is used as a liquid crystal alignment film, the degree of afterimage is not clear.

[0007]

The object of the present invention is to prevent the heat resistance of polyimide from being sacrificed.
By providing a novel polyimide-based resin that can be used as an electric and electronic material, is particularly excellent in electrical characteristics without a residual phenomenon, and is useful as a liquid crystal alignment film that can have a pretilt angle of about 1 to 4 degrees. is there.

[0008]

The inventors of the present invention have conducted various studies to solve the above-mentioned problems, and as a result, a polyesterimide having a structural unit of the above formula [1] as a diamine component has low-temperature curability. The present invention has been completed by discovering that the liquid crystal alignment film using this resin has excellent heat resistance, and that the liquid crystal alignment film has good electrical characteristics such as no afterimage phenomenon.

That is, the constitution of the present invention is as follows. Formula (1) [1] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [2] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of structural units. (2) Formula [1] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [3] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of structural units. (3) Formula [1] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [2] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [3] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of structural units. (4) Formula [1] (However, A is 3, 3 ', 4, 4' over a biphenyl group, or
Other shows the 1,1,1,3,3,3 over hexafluoroisopropylidene over 2,2 Bisufutariru group. ) A polyester imide comprising a structural unit represented by: (5) A liquid crystal alignment film using the polyesterimide described in any one of (1) to ( 3 ) above. (6) A liquid crystal display device comprising the liquid crystal alignment film described in (5) above. (7) Formula [1] (However, A is a phenyl group, 3,3 ', 4,4'-bif
Phenyl group or 1,1,1,3,3,3-hexaful
Indicates an oroisopropylidene-2,2-bisphthalyl group
You ) Polyester imide consisting of structural unit
A liquid crystal alignment film characterized by using. (8) Liquid crystal having the liquid crystal alignment film according to (7) above
Display element.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Formula [5] used for producing the polyesterimide of the present invention

[Chemical 20] 2,2-diethyl-1,3-propanediol-
Bis (4-aminobenzoate) is 2,2-diethyl-1,3-propane obtained by reacting p-nitrobenzoyl chloride with 2,2-diethyl-1,3-propanediol in the presence of pyridine. It is produced by catalytic reduction of diol-bis (4-nitrobenzoate) in the presence of a palladium catalyst.

[Chemical 21]

Further, as another diamine, a compound represented by the formula [6]

[Chemical formula 22] 2,2-bis (4-aminophenyl) -1,1,1,
3,3,3-hexafluoropropane (hereinafter abbreviated as bisA-AF) and formula [7]

[Chemical formula 23] 2,2-bis (4-aminophenoxyphenyl) -1,1,1,3,3,3-hexafluoropropane represented by

The tetracarboxylic dianhydride has the formula [8]

[Chemical formula 24] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Compounds, specifically, pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 1, 1, 1, 3,
It is 3,3, -hexafluoroisopropylidene-2,2-bisphthalic acid dianhydride (6FDA).

The molar ratio of each structural unit in the polyesterimide molecule consisting of the structural unit represented by the formula [1] and the formula [2] or the formula [3] is 5 to 70 mol in the formula [1]. %, Formula [2] or formula [3] is 95-30
It is preferably mol%. When the ratio of the formula [1] is 70 mol% or more, there is a problem that the film forming property of the obtained polyesterimide is deteriorated.

To synthesize the polyesterimide of the present invention, a polyimide precursor polyamic acid obtained by a condensation reaction of a tetracarboxylic dianhydride and a diamine is coated on a substrate and subjected to heat treatment for dehydration reaction. A method of forming a polyester imide film on a substrate is preferable. More specifically, polyamic acid is converted into N-methyl-2-
Pyrrolidone (NMP), dimethylacetamide (DMA
c), dissolved in a solvent such as dimethylformamide (DMF), dimethylsulfoxide (DMSO), butyl cellosolve, and ethyl carbitol to prepare a 0.1 to 30% by weight solution, and this solution is applied on a substrate to form a thin film. Let After coating, 100 to 450 ° C, preferably 180 to 2
Heat treatment is performed at 90 ° C., and a dehydration ring closure reaction is performed to provide a polyesterimide film.

To form the liquid crystal alignment film of the present invention on a substrate, a polyimide precursor polyamic acid obtained by a condensation reaction of tetracarboxylic dianhydride and diamine is coated on the substrate and heat-treated. A method of forming a polyimide-based polymer film on a substrate by a dehydration reaction is preferable.
More specifically, polyamic acid is converted into NMP and DMA.
Dissolve in a solvent such as c, DMF, DMSO, butyl cellosolve, ethyl carbitol and adjust to a solution of 0.1 to 30% by weight, and use this solution for brush coating, dipping, spin coating, spraying and printing. And the like to form a thin film on the substrate. After coating, heat treatment is performed at 100 to 450 ° C., preferably 180 to 290 ° C., and a dehydration ring closure reaction is performed to provide a polyimide polymer film. If the surface of the substrate is treated with a silane coupling agent before coating and a polymer film is formed thereon, the adhesion between the film and the substrate can be improved. Then, the coated surface is rubbed in one direction with a cloth or the like to obtain a liquid crystal alignment film.

The above polyamic acid is obtained by the condensation reaction of tetracarboxylic dianhydride and diamine.
These reactions are performed under anhydrous conditions under the conditions of DMAc, NMP, DM
It is carried out in a solvent such as F, DMSO, dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol, halogenated phenol, cyclohexanone, dioxane or tetrahydrofuran, preferably in a DMAc solvent at a temperature of 50 ° C. or lower.

The substrate used as a liquid crystal display element is usually one on which an electrode, specifically, a transparent electrode of ITO (indium oxide-tin oxide) or tin oxide is formed. An insulating film for preventing alkali elution from the substrate, an undercoat film such as a color filter or a color filter overcoat may be provided between the electrodes, and an overcoat film such as an insulating film or a color filter film may be provided on the electrodes. It may be provided. Further, an active element such as a TFT element or a non-linear resistance element may be formed. For these electrodes, undercoat, and other internal structure of the liquid crystal cell, the structure of a conventional liquid crystal display element can be used.

The substrate thus formed is made into cells, liquid crystal is injected, and the injection port is sealed to produce a liquid crystal display element. As the liquid crystal to be enclosed, various liquid crystals such as a normal nematic liquid crystal and a liquid crystal to which a dichroic dye is added can be used. The liquid crystal alignment film of the present invention has a feature that there is no afterimage phenomenon.

The liquid crystal display device of the present invention is characterized in that it has a liquid crystal alignment film having a characteristic that the residual voltage is low and therefore there is no afterimage phenomenon, that is, the liquid crystal alignment film according to the present invention. , A voltage application unit, a liquid crystal alignment film, a liquid crystal layer, and the like.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The physical properties of the polyesterimides obtained in the examples were measured by the following methods. Decomposition temperature (Td): A differential thermogravimetric simultaneous measurement device (TG / DTA-220 manufactured by Seiko Denshi Kogyo Co., Ltd.) was used to measure the temperature at a temperature rising rate of 10 ° C./min. Glass transition temperature (Tg): measured with a differential scanning calorimeter (DSC-200 manufactured by Seiko Instruments Inc.) at a temperature rising rate of 10 ° C. per minute.

The degree of afterimage was measured by the CV curve method. In the C-V curve method, the voltage V = ± 10V is applied to the liquid crystal cell.
The triangular wave (frequency: 0.0036 Hz) is applied, and the capacitance C that changes when sweeping by superposing an alternating current of 25 mV and 1 kHz is recorded. Here, if the voltage is first swept to the positive side, the capacity increases. Next, when it is swept to the negative side, the capacitance becomes small and becomes zero. Sweeping from 0 to the negative side increases the capacity again, and sweeping to the positive side decreases the capacity again. The waveform after repeating this for several cycles is as shown in FIG. When the charge is deviated and stabilized on the surface of the liquid crystal alignment film, the voltage draws a hysteresis curve on both the positive side and the negative side. For the residual charge, two tangents are drawn on the C-V curve on both the positive side and the negative side, and the intersections (α1 to α4) of these and the capacitance (C ₀ ) at V = 0 are obtained, respectively. The positive side is the positive side, and the negative side is the negative side. The potential difference between the two points is obtained, and then the average voltage difference between these two points is obtained. This value becomes a parameter for stabilizing the bias of the electric charge if the film thickness of the liquid crystal cell and the film thickness of the alignment film are the same. That is, the residual image phenomenon can be alleviated by using an alignment film having a small residual charge.

The voltage holding ratio was measured by a circuit as shown in FIG. The measurement method was performed by reading a drain (V _D ) which changes by applying a rectangular wave (V _S ) having a gate pulse width of 69 ms, a gate frequency of 60 Hz and a wave height of ± 4.5 V to the source with an oscilloscope. For example, when a positive rectangular wave is applied to the source, the drain (V _D ) shows a positive value until the next negative rectangular wave is applied. If the retention rate is 100%, V _D shown in FIG. 3 takes a rectangular trajectory shown by a dotted line, but normally V _D becomes a trajectory shown by a solid line gradually approaching 0. Then, the area of the measured track (the area surrounded by the track where V = 0 and the track), that is, the shaded area was calculated, and this was repeated four times to obtain the average value. 100% of the area when the voltage does not decrease at all
The relative value of the measured area was defined as the voltage holding ratio (%). The pretilt angle was measured by the crystal rotation method.

Example 1 Production of Polyesterimide Consisting of Structural Units Represented by Formula [1] and Formula [2]: 1) 2,2-Diethyl-1,3-propanediol-bis Represented by Formula [5] Production of (4-aminobenzoate). Into a 500 ml three-necked flask equipped with a stirrer, add 200 ml of tetrahydrofuran (THF) and 30 ml of pyridine,
2,2-diethyl-1,3-propanediol 30.9 g (0.26
mol) was added and the mixture was stirred at room temperature. A solution prepared by dissolving 13.0 g (0.07 mol) of p-nitrobenzoyl chloride in 50 ml of THF was added dropwise over 30 minutes, and the reaction was carried out for 12 hours. After the reaction is complete, add this reaction mixture to 1 liter of water and add ethyl acetate.
Extracted with 1.5 liters. Then, the organic layer was washed with 3N hydrochloric acid to 3 times.
The extract was washed three times with saturated aqueous sodium hydrogen carbonate and further with water. The obtained ethyl acetate layer was dried over anhydrous sodium sulfate, the solvent was evaporated under reduced pressure, and the obtained crystals were recrystallized twice with ethyl acetate to give 2,2-diethyl-1,3-propanediol- 15.9 g (yield 78.1%) of bis (4-nitrobenzoate) was obtained. The melting point was 141.4-142.4 ° C. After confirming the structure of this compound by IR and NMR, the compound was subjected to catalytic reduction. That is, 12.6 g (0.03 mol) of 2,2-diethyl-1,3-propanediol-bis (4-nitrobenzoate)
Was dissolved in 300 ml of ethyl acetate, 1 g of 5 wt% palladium-carbon was added, and catalytic reduction was carried out at room temperature and atmospheric pressure. After completion of the reaction, the catalyst was filtered off, the solvent was distilled off under reduced pressure, and the obtained crystals were recrystallized twice with n-heptane / ethyl acetate to give 2,2-
Diethyl-1,3-propanediol-bis (4-aminobenzoate) 8.60 g (yield 77.8%) was obtained. Melting point 13
The temperature was 3.4 to 135.1 ° C. The structure of this compound was confirmed by IR and NMR.

2) Polymerization reaction In a 50 ml three-necked flask, 2,2-diethyl-1,3-propanediol-bis (4-aminobenzoate) 0.2778 was added.
g (0.75 mmol), 2,2-bis (4-aminophenyl)-
1,1,1,3,3,3-hexafluoropropane (hereinafter bis A-A
(Abbreviated as F) 0.2507 g (0.75 mmol) and 3 ml of DMAc were added and dissolved under stirring at room temperature under a nitrogen stream. Next, this liquid was kept at 10 ° C., and 0.4413 g (1.5 mmol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added. DM
The vessel wall was rinsed with 3 ml of Ac, and the reaction was continued for 3 hours. The obtained reaction liquid was N-methyl-2-pyrrolidone / butyl cellosolve / dimethylformamide = 16/3/1
After being diluted to 4.6 wt% with a solvent, it was applied onto a glass substrate by a spin coating method (spinner method). 1 at 100 ℃ after coating
After preheating for 0 minutes, the temperature was raised to 200 ° C. in 40 minutes. Finally, it is baked at 200 ° C for 90 minutes to give a film thickness of 600.
A polyesterimide film of was obtained. This polyesterimide has a decomposition temperature of 425.5 ° C and a glass transition temperature of 258.9.
It was ℃. Further, the remaining reaction solution was poured into 300 ml of ethanol, and the deposited precipitate was filtered. The filtration residue was dried under reduced pressure at room temperature to obtain a polyamic acid. The intrinsic viscosity of this polyamic acid is 0.37 (30 ° C, 0.5 g / dl, N
MP solution).

3) Measurement of electrical characteristics and pretilt angle Subsequently, the film surfaces of the two substrates were each rubbed, and a liquid crystal cell having a cell thickness of 6 μm was assembled so that the rubbing directions were antiparallel. LCD FB
-01 was enclosed. Then, the liquid crystal was heat-treated at 120 ° C. for 30 minutes. When the residual charge of this liquid crystal element was measured, it was 0.03 V at 20 ° C. The voltage holding ratio is 2
It was 92.4% at 0 ° C. Further, a liquid crystal cell having a cell thickness of 20 μm was assembled by the same method, and a liquid crystal Z manufactured by Merck Ltd.
LI-1132 was enclosed and the pretilt angle after heat treatment was determined to be 1.6 degrees.

Examples 2 to 4 2,2-diethyl-1,3-propanediol-bis (4-
Aminobenzoate) and bisA-AF were changed in accordance with the procedure 2) in Example 1 except that the component ratio was changed. Table 1 shows the component ratios and the thermophysical property values of the obtained polyesterimide.
Shown in.

Example 5 2) of Example 1 except that the tetracarboxylic dianhydride was changed to pyromellitic dianhydride (0.3272 g, 1.5 mmol).
It was done according to. This polyesterimide had a decomposition temperature of 427.5 ° C.

Example 6 Tetracarboxylic acid dianhydride is changed to 1,1,1,1,3,3,3,3-hexafluoroisopropylidene-2,2-bisphthalic acid dianhydride (0.6664 g, 1.5 mmol). Example 1 except
No. 2). This polyester imide is
The decomposition temperature was 404.3 ° C.

Example 7 Production of Polyesterimide Consisting of Structural Units Shown in Formulas [1] and [3]: 2,2-diethyl-1,3-propanediol-bis (4-) in a 50 ml three-necked flask. Aminobenzoate) 0.0556
g (0.15 mmol), 2,2-bis (4-aminophenoxyphenyl) -1,1,1,3,3,3-hexafluoropropane 0.699
9 g (1.35 mmol), dimethylacetamide (hereinafter DMA
(abbreviated as c) 3 ml was added, and the mixture was stirred and dissolved at room temperature under a nitrogen stream. Next, this liquid was kept at 10 ° C., and 0.4413 g (1.5 mmo) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride
l) was added. The vessel wall was rinsed with 3 ml of DMAc, and the reaction was continued for 3 hours. The obtained reaction solution was diluted with a solvent of N-methyl-2-pyrrolidone / butyl cellosolve / dimethylformamide = 16/3/1 to 4.6 wt% and then applied on a glass substrate by a spin coating method (spinner method).
After coating, preheat at 100 ° C for 10 minutes and then 40
The temperature was raised to 200 ° C. in minutes. Finally, it was baked at 200 ° C. for 90 minutes to obtain a polyesterimide film having a thickness of 600. This polyesterimide had a decomposition temperature of 519.7 ° C. Further, the remaining reaction solution was poured into 300 ml of ethanol, and the deposited precipitate was filtered. The filtration residue was dried under reduced pressure at room temperature to obtain a polyamic acid. The intrinsic viscosity of this polyamic acid is 0.48 (30 ° C, 0.5g / dl, NM
P solution).

Examples 8-10 2,2-diethyl-1,3-propanediol-bis (4-
Aminobenzoate), and 2,2-bis (4-aminophenoxyphenyl) -1,1,1,3,3,3-hexafluoropropane, except that the component ratio was changed. . Table 1 shows the component ratios and the thermophysical property values of the obtained polyesterimide.

Example 11 The procedure of Example 7 was repeated except that the tetracarboxylic dianhydride was changed to pyromellitic dianhydride (0.3272 g, 1.5 mmol). This polyesterimide has a decomposition temperature of 4
It was 46.7 ° C.

Example 12 Tetracarboxylic acid dianhydride is changed to 1,1,1,1,3,3,3,3-hexafluoroisopropylidene-2,2-bisphthalic acid dianhydride (0.6664 g, 1.5 mmol). Example 7 except
It was done according to. This polyesterimide had a decomposition temperature of 473.7 ° C.

Example 13 Production of Polyesterimide Consisting of Structural Units Shown in Formula [1], Formula [2] and Formula [3]: 2,2-Diethyl-1,3-propanediol in a 50 ml three-necked flask. -Bis (4-aminobenzoate) 0.3334
g (0.9 mmol), 2,2-bis (4-aminophenyl) -1,
1,1,3,3,3-hexafluoropropane 0.1003g (0.3mmo
l), 2,2-bis (4-aminophenoxyphenyl) -1,
1,1,3,3,3-hexafluoropropane 0.1555g (0.3mmo
l) Dimethylacetamide (hereinafter abbreviated as DMAc) 3 ml
Was added, and the mixture was stirred and dissolved at room temperature under a nitrogen stream. Next, this liquid was kept at 10 ° C., and 0.4413 g (1.5 mmol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added.
The vessel wall was rinsed with 3 ml of DMAc, and the reaction was continued for 3 hours. The obtained reaction liquid was N-methyl-2-pyrrolidone / butyl cellosolve / dimethylformamide = 16/3
After diluting to 4.6 wt% with a / 1 solvent, it was applied onto a glass substrate by spin coating (spinner method). 100 ° C after application
After 10 minutes of preheating, the temperature was raised to 200 ° C. in 40 minutes. Finally, it was baked at 200 ° C. for 90 minutes to obtain a polyesterimide film. The decomposition temperature of this polyesterimide was 426.9 ° C. Further, the remaining reaction solution was poured into 300 ml of ethanol, and the deposited precipitate was filtered. The filtration residue was dried under reduced pressure at room temperature to obtain a polyamic acid. The intrinsic viscosity of this polyamic acid is 0.31 (30 ℃,
0.5 g / dl, NMP solution).

Example 14 Production of Polyesterimide Consisting of Structural Units Shown Only in Formula [1]: 2,2-Diethyl-1,3-propanediol-bis (4-aminobenzoate) 0.5557 in a 50 ml three-necked flask.
g (1.5 mmol) and 3 ml of DMAc were added, and the mixture was stirred and dissolved under a nitrogen stream at room temperature. Then keep the solution at 10 ° C for 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride 0.4413
g (1.5 mmol) was added. The vessel wall was rinsed with 3 ml of DMAc, and the reaction was continued for 3 hours. The obtained reaction solution was diluted with a solvent of N-methyl-2-pyrrolidone / butyl cellosolve / dimethylformamide = 16/3/1 to 4.6 wt% and then applied on a glass substrate by a spin coating method (spinner method). After coating, preheating was performed at 100 ° C. for 10 minutes, and then the temperature was raised to 200 ° C. in 40 minutes. Finally 200
It was baked at 90 ° C. for 90 minutes to obtain a polyesterimide film. This polyesterimide had a decomposition temperature of 422.1 ° C and a glass transition temperature of 263.5 ° C. Further, the remaining reaction solution was poured into 300 ml of ethanol, and the deposited precipitate was filtered. The filtered material was dried under reduced pressure at room temperature to obtain a polyamic acid. The intrinsic viscosity of this polyamic acid is 0.42 (30
C., 0.5 g / dl, NMP solution).

[0036]

[Table 1] 1) BPDA = 3,3,4 ′, 4′-biphenyltetracarboxylic dianhydride 2) PMDA = pyromellitic dianhydride 3) 6FDA = hexafluoroisopropylidene-2,2-
Bisphthalic dianhydride 4) Intrinsic viscosity of polyamic acid: in NMP, 0.5 g / dl,
It was measured at 30 ° C. 5) Measurement was performed at a temperature rising rate of 10 ° C / min. 6) Measured at a temperature rise rate of 10 ° C / min, weight loss of 5%
Was used as the decomposition point.

[0037]

The polyesterimide obtained by the present invention has a high glass transition temperature of 230 to 280 ° C. and a decomposition temperature of 420 to 520 ° C., and can be used at high temperatures.
Also, by having a flexible aliphatic ester in the main chain, it is possible to cure at a relatively lower temperature than conventional polyimides. Furthermore, the liquid crystal alignment film using this polyesterimide has a high voltage holding ratio, no afterimage phenomenon, excellent electrical characteristics, and a good pretilt angle of 1.6 degrees, so it is an alignment film for ordinary liquid crystal cells (for TN and TFT). It is useful as a material.

[0038]

[Brief description of drawings]

FIG. 1 is a diagram showing a CV hysteresis curve.

FIG. 2 is a diagram showing a circuit of a voltage holding ratio measuring device.

FIG. 3 is a diagram showing a change with time of a drain (V _D ).

Claims (8)

(57) [Claims] 1. A formula [1] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [2] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of structural units. 2. A formula [1] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [3] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of structural units. 3. A formula [1] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [2] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Structural unit and formula [3] (However, A represents a phenyl group, a 3,3 ′, 4,4′-biphenyl group, or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of structural units. 4. A formula [1] (However, A represents a 3,3 ′, 4,4′-biphenyl group or a 1,1,1,3,3,3-hexafluoroisopropylidene-2,2-bisphthalyl group.) Polyester imide consisting of. 5. A liquid crystal alignment film comprising the polyesterimide according to any one of claims 1 to 3 . 6. A liquid crystal display device comprising the liquid crystal alignment film according to claim 5. 7. A formula [1] (However, A is a phenyl group, 3,3 ', 4,4'-bif
Phenyl group or 1,1,1,3,3,3-hexaful
Indicates an oroisopropylidene-2,2-bisphthalyl group
You ) Polyester imide consisting of structural unit
A liquid crystal alignment film characterized by using. 8. A liquid crystal alignment film according to claim 7 is provided.
Liquid crystal display device.