KR100321260B1 - Polyamic acid, and liquid crystal aligning film using the same - Google Patents

Abstract

The present invention provides a polyamic acid prepared by polymerizing tetracarboxylic dianhydride and an aromatic diamine having an aliphatic carbon component in the main chain of Formula 1, a polyimide resin obtained by imidization of such a polyamic acid, and a polyimide resin. The polyimide resin of the present invention is suitable for application to liquid crystal alignment films because it has heat resistance, transparency, and stable pretilt angle as a liquid crystal alignment film, and particularly requires a high pretilt angle. It is useful as a liquid crystal aligning film of STN liquid crystal display device.

[Formula 1]

Wherein n is an integer between 2-16,

The position of the diamine is the position of one of ortho, para and meta.

Description

POLYAMIC ACID, AND LIQUID CRYSTAL ALIGNING FILM USING THE SAME using polyamic acid and polyimide resin

The present invention relates to a novel polyamic acid and a polyimide resin prepared by polymerizing tetracarboxylic dianhydride and an aromatic diamine having an aliphatic carbon component in a main chain thereof, and a liquid crystal alignment film made from such a polyimide resin. And the liquid crystal alignment film produced from the polyimide resin can increase the pretilt angle in accordance with the required characteristics of the STN-LCD.

Recently, as the liquid crystal display has been enlarged, the wide field of view is required for the liquid crystal display as the use of a wall-mounted TV is gradually expanded in offices such as laptops. STN-LCD (super twisted nematic-LCD) as a liquid crystal display module is used for contrast and It has excellent visual characteristics and is in the spotlight. In such STN liquid crystal display, liquid crystal molecules should be twisted at 240 to 270 ° with respect to the major axis direction. However, when the conventional polyimide liquid crystal aligning film is used for the production of STN-LCD, the pretilt angle of the liquid crystal aligning film is too small, so that the liquid crystal cannot be twisted by 240 to 270 ° with respect to the major axis direction, thereby providing satisfactory display performance. none. Therefore, there is a demand for development of an alignment film capable of stably maintaining such a large pretilt angle.

Various methods for increasing the pretilt angle in the polyimide resin for liquid crystal alignment films have been studied. Specifically, a method of introducing a fluoroalkyl group into the polymer chain (US Pat. No. 4,735,492), which uses an amine having a long fluoroalkyl group, has been studied. The method (Japanese Patent Application No. H1-180518), the method using the metal complex which has a long chain alkyl chain (13th Liquid Crystal Forum printed matter, October, 1987), etc. were proposed. However, these methods did not provide a stable large pretilt angle in liquid crystal alignment films, especially in STN-LCDs requiring a wide viewing angle. In addition, the demand for a color display module is rapidly increasing, but since the heat resistance of the color filter is limited, development of a low-temperature curing type alignment film is required.

One object of the present invention is to overcome the problems of the prior art described above, and to provide a polyamic acid resin and a polyimide resin for a liquid crystal alignment film which can ensure a high pretilt angle in a stable form regardless of the curing temperature.

Another object of the present invention is to provide a liquid crystal aligning film capable of providing a high pretilt angle made from the polyamic acid and polyimide of the present invention in a stable form and a liquid crystal display device using the same.

That is, the present invention provides a polyamic acid resin prepared by reacting an aromatic diamine having an aliphatic carbon component and tetracarboxylic dianhydride in a main chain represented by the following Chemical Formula 1, and a polyimide resin prepared by curing the same.

Wherein n is an integer between 2-16,

The position of the diamine is the position of one of ortho, para and meta.

Hereinafter, the present invention will be described in more detail.

Conventionally, a polyimide resin mainly used as a material for a liquid crystal alignment layer is generally a polyamic acid resin (hereinafter referred to as "PAA resin") by reacting tetracarboxylic dianhydride and diamine in a suitable organic solvent, as shown in Scheme 1 below. After the preparation, the polyamic acid is prepared by imidization (dehydration) at a high temperature. Such polyimide resin may have various molecular structures and physical properties depending on the type of monomer used.

Wherein Q is a tetracarboxylic dianhydride monomer,

R is a diamine monomer.

Such polyimide resins are insoluble and insoluble ultra-high heat resistant resins, which have excellent thermal oxidation resistance, and long-term use temperature of about 260 ° C and short-term use temperature of about 480 ° C. In addition, 전기 excellent electrochemical and mechanical properties ⑷ excellent radiation resistance and low temperature properties ⑸ intrinsic flame retardancy and ⑹ excellent chemical resistance. Due to these advantages, it is used in a wide range of fields such as automotive materials, aviation materials, spacecraft materials, and electronic materials, and recently, it is also used in display materials such as optical fibers and liquid crystal alignment films.

The present invention is an improvement of the above-described conventional polyimide resin for liquid crystal aligning film, wherein the polyamic acid resin produced by solution polymerization of a diamine component and tetracarboxylic dianhydride, having an aliphatic carbon component in the main chain of Formula 1 An aromatic diamine is used to improve molecular structure and physical properties. In the present invention, the molar ratio of the diamine component of Chemical Formula 1 is 5 to 100 mol%, more preferably 20 to 100 mol% based on the total diamine compound.

In the present invention, in addition to the aromatic diamine having an aliphatic carbon component in the main chain represented by Formula 1, other diamine compounds may be used together as long as the effects of the diamine compound are not impaired. Examples of such diamine compounds include, but are not necessarily limited to, at least one of the following diamines: paraphenylenediamine (p-PDA), metaphenylenediamine (m-PDA), oxydianiline, methylene Dianiline, metabisaminophenoxydiphenylsulfone, parabisaminophenoxydiphenylsulfone.

Examples of diamines usable in addition to the modified aliphatic diamine in the present invention are shown in the following formula (2).

In the present invention, as the tetracarboxylic dianhydride, one or more types of tetracarboxylic dianhydrides represented by the following Chemical Formula 3 may be used, for example, pyromellitic dianhydride (hereinafter referred to as "PMDA") which is an aromatic tetracarboxylic dianhydride. Benzophenonetedracarboxylic dianhydride (hereinafter referred to as "BTDA"), oxydiphthalic dianhydride (hereinafter referred to as "ODPA"), bisphthalic dianhydride (hereinafter referred to as "BPDA"). ), Hexafluoroisopropylidenediphthalic dianhydride (hereinafter referred to as "HFDA") or cyclohexane-1,2,4,5, -tetracarboxylic dianhydride, which is an aliphatic tetracarboxylic dianhydride, 5- ( 2,5-dioxotetrahydroxyfuryl) -3-methyl-3-cyclohexene-1,2-tetracarboxylic dianhydride (hereinafter referred to as "DOCDA"), bicyclo (2,2,2) octa -7-en-2,3,5,6-tetracarboxylic dianhydride (hereinafter referred to as "BODA"), cyclopentane-1,2 , 3,4-tetracarboxylic dianhydride, cyclobutane-1,2,3,4-tetracarboxylic dianhydride (hereinafter referred to as "CBDA"), butane-1,2,3,4-tetracarboxylic At least one selected from acid dianhydrides and cyclopentane-1,2,4,5-tetracarboxylic dianhydrides may be used.

The polyamic acid prepared from the characteristic diamine monomer and tetracarboxylic dianhydride of the present invention as described above has the following formula (4) as a repeating unit.

Where Is at least one selected from the group of Formula 3

Tetracarboxylic dianhydride monomer,

Is at least one diamine monomer selected from the group consisting of the aromatic diamine of the general formula (1) and / or the general formula (2).

The polyimide resin of the present invention is prepared by heating the polyamic acid of Chemical Formula 4 or by imidization in the presence of a dehydrating agent or an imidization catalyst, and the following Chemical Formula 5 is a repeating unit.

Where Wow Is as defined in the formula (4).

The polyamic acid viscosity according to the present invention is 5 to 100 cps (solid content 5%, 25 ° C.), and solid content is 2 to 30 wt%. Polyimide obtained after curing has a glass transition temperature of 150 ~ 400 ℃ and heat resistance of 350 ℃ or more. In addition, the polyimide liquid crystal alignment film prepared from the polyamic acid of the present invention not only exhibits excellent printability, liquid crystal alignment, and chronological stability, but also has a pretilt angle of about 2 ° to 8 ° to provide a liquid crystal alignment film for TN-LCD. Moreover, it is suitable also for use as a liquid crystal aligning film for STN-LCD, and is excellent also in pretilt angle stability by the difference of hardening temperature. In addition, by adjusting the n value in the aromatic diamine of Formula 1, it is possible to freely design different pretilt angles.

Furthermore, the polyimide resin of the present invention is dimethyl acetamide (DMAc), dimethyl formamide (DMF), N-methyl-2-pyrrolidinone (NMP) and Easily dissolved at room temperature with respect to organic solvents such as methacresol, including the same polar solvent. In addition, low boiling point solutions such as tetrahydrofuran (hereinafter referred to as "THF"), chloroform, acetone, ethyl acetate, and Υ-butyrolactone, 2-butoxyethanol, 2-ethoxyethanol, 3-butoxy Even low hygroscopic solvents such as propanol or mixed solvents thereof exhibit high solubility of at least 10% by weight at room temperature.

In the present invention, the polyamic acid is prepared by solution polymerization of 5 to 100 mol% of aromatic diamine components having aliphatic carbon components, other aromatic diamine compounds, and tetracarboxylic dianhydride in the main chain represented by the formula (1), and polyimide resin Can be produced by imidizing (dehydrating) the polyamic acid thus obtained.

The organic solvent used in the polymerization of the polyamic acid in the present invention is not particularly limited as long as it can dissolve the unique diamine component of the present invention and does not degrade the reaction. For example, NMP, DMAc, DMF, etc. can be used, and in addition to THF, chloroform Etc. can be used as a solvent. Among the solvents that can be used, NMP, DMAc, and DMF are preferable because they catalyze the polymerization reaction during the polymerization of the polyamic acid and promote imidization in the subsequent imidization process.

In the present invention, since the reaction ratio of the dianhydride and diamine to be reacted at the time of polyamic acid polymerization is 1: 1, the two monomers are reacted in the same molar ratio, and the total amount of the dianhydride and diamine monomer in the total reaction solution is 2 to 30% by weight. When it reacts, 2-30 weight% of polyamic-acid solids melt | dissolve in the resultant polyamic-acid solution. In the present invention, the synthesis of polyamic acid is carried out by reacting at a reaction temperature of 0 to 30 ° C. for 10 to 48 hours.

The polyimide resin of the present invention is produced by thermosetting the polyamic acid obtained by the above method. It is preferable to dry hardening conditions at 100-120 degreeC using a heating plate or oven, and to heat up in an oven under nitrogen atmosphere gradually, and to heat for 30 minutes-2 hours in the temperature range of 250-350 degreeC.

In the liquid crystal alignment film of the present invention, a polyimide resin solution is coated on a transparent conductive glass substrate by a roll coating method, a spin coating method, or a printing method to form an alignment film having a thickness of 0.1 to 1 μm. The liquid crystal display device is manufactured by rubbing, and the liquid crystal alignment layer is mounted on both upper and lower substrates.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the protection scope of the present invention.

Preparation Example 1 Preparation of Ethylene Glycol-3-Dinitrobenzoate (EG-3-DNB)

Dissolve 18.56 g (0.1 mol) of 3-nitrobenzoyl chloride in 130 ml DMAc solvent while slowly passing nitrogen gas through a 250 ml reactor equipped with a stirrer and a nitrogen injector, followed by 3.1 g (0.05 mol) of ethylene glycol, 7.91 g (0.1 mol) of pyridine and 60 ml DMAc mixed solution were slowly added dropwise. At this time, the reaction temperature was 4-5 ° C. After the addition of the mixed solution was completed, the reaction was performed for 3 hours while stirring the entire reaction solution. After completion of the reaction, precipitated in non-solvent methanol to obtain a white reactant, which was washed two more times with methanol and hexane, and recrystallized twice with ethyl acetate / hexane cosolvent to yield EG-3-DNB (yield: 81.2%).

Preparation Example 2 Preparation of Ethylene Glycol Diaminobenzoate (EG-3-DAB)

After EG-3-DNB (7.42g, 0.04mole) was dissolved in 200ml of ethanol, Pd / C (5%) was added to a hydrogen reactor with 2.0g for 3 hours. The reaction mixture was filtered and the reaction solvent was distilled under reduced pressure, and then recrystallized from an ethyl acetate / hexane co-solvent to obtain EG-3-DAB of Chemical Formula 6 (yield: about 70%, mp: 173-175 ° C.)

Preparation Example 3 Preparation of 1,10-decamethylene diol-3-dinitrobenzoate (DMD-3-DNB)

DMD-3-DNB was obtained in the same manner as in Preparation Example 1, except that 8.71 g of 1,10-decane diol was used instead of 3.1 g of ethylene glycol (yield: 59.2%).

Preparation Example 4 Preparation of 1,10-decamethylene diol-3-diaminobenzoate (DMD-3-DAB)

12.14 g of DMD-3-DNB was used instead of 7.42 g of EG-3-DNB to carry out the same procedure as in Preparation Example 2, to obtain DMD-3-DAB of the following Chemical Formula 7 (yield: about 43.1%; mp : 133-134 ° C.).

Preparation Example 5 Preparation of 1,4-butane diol-3-dinitrobenzoate (BTD-3-DNB)

BTD-3-DNB was obtained in the same manner as in Production Example 1, except that 4.5 g of 1,3-butane diol was used instead of 3.1 g of ethylene glycol (yield: 79.2%).

Preparation Example 6 Preparation of 1,4-butane diol-3-diaminobenzoate (BTD-3-DAB)

BTD-3-DAB of the following Chemical Formula 8 was obtained in the same manner as in Preparation Example 2, except that 8.54 g of BTD-3-DNB was used instead of 7.42 g of EG-3-DNB. (Yield 69.8%; mp: 217-218 ° C.).

Preparation Example 7 Preparation of 1,7-heptane diol-4-dinitrobenzoate (HTD-4-DNB)

HTD-4-DNB was obtained in the same manner as in Preparation Example 1, except that 6.6 g of 1,7-heptane diol was used instead of 3.1 g of ethylene glycol (yield: 49.5%).

Preparation Example 8 Preparation of 1,7-heptane diol-4-dinitrobenzoate (HTD-4-DAB)

HTD-4-DAB of the following Chemical Formula 9 was obtained in the same manner as in Preparation Example 2, except that 10.22 g of HTD-4-DNB was used instead of 7.42 g of EG-3-DNB (yield: about 19.2%; mp : 102-103 ° C.).

Preparation Example 9 Preparation of 1,7-heptane diol-2-dinitrobenzoate (HTD-2-DNB)

HTD-2-DNB was obtained in the same manner as in Preparation Example 1, except that 6.6 g of 1,7-heptane diol was used instead of 3.1 g of ethylene glycol (yield: 49.5%).

Preparation Example 10 Preparation of 1,7-heptane diol-2-dinitrobenzoate (HTD-2-DAB)

HTD-2-DAB of the following Chemical Formula 10 was obtained in the same manner as in Preparation Example 2, except that 10.22 g of HTD-2-DNB was used instead of 7.42 g of EG-3-DNB (yield: about 19.2%; mp : 102-103 ° C.).

Preparation Example 11 Preparation of 1,10-decamethylene diol-4-dinitrobenzoate (DMD-4-DNB)

DMD-4-DNB was obtained in the same manner as in Preparation Example 1, except that 8.71 g of 1,10-decane diol was used instead of 3.1 g of ethylene glycol (yield: 59.2%).

Preparation Example 12 Preparation of 1,10-decamethylene diol-4-diaminobenzoate (DMD-4-DAB)

12.14 g of DMD-4-DNB was used instead of 7.42 g of EG-3-DNB to prepare DMD-4-DAB of the following Formula 11, obtaining a yield of about 43.1%; mp : 133-134 ° C.).

Example 1

While slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, a thermostat, a nitrogen injector, a dropping funnel and a cooler, EG-3-DAB (0.62 g, 2 mmoles) of the formula (6) was added to 11.16 g of the reaction solvent DMAc. After dissolving, ODPA (0.62g, 2mmole) was slowly added while passing through nitrogen gas, and then reacted at 10 ° C. for 7 hours to obtain a 10 wt% polyamic acid solution, and evaluated the physical properties of the results in Tables 1 to 3 below. Shown in

Example 2

While slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, a temperature controller, a nitrogen injector, a dropping funnel and a cooler, DMD-3-DAB (0.84 g, 2 mmoles) of the formula (7) was added to 13.14 g of the reaction solvent. After dissolving, ODPA (0.62g, 2mmole) was slowly added while passing through nitrogen gas and reacted at 10 ° C. for 7 hours to obtain a 10 wt% polyamic acid solution, and the overall physical properties thereof were evaluated in Tables 1 to 3 below. Indicated.

Example 3

While slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, a temperature controller, a nitrogen injector, a dropping funnel and a cooler, BTD-3-DAB (0.68 g, 2 mmoles) of the formula (8) was added to 11.34 g of the reaction solvent DMAc. After dissolving, DOCDA (0.53 g, 2 mmol) was slowly added while passing through nitrogen gas, and reacted at 10 ° C. for 7 hours to obtain a 10 wt% polyamic acid solution, and evaluated the physical properties thereof. Shown in

Example 4

While slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, a temperature controller, a nitrogen injector, a dropping funnel and a cooler, BTD-3-DAB (0.68 g, 2 mmoles) of the structural formula 8 was reacted with DMAc 11.79 After dissolving in g, DOCDA (0.26g, 1mmole) and BTDA (0.32g, 1mmole) were slowly added while passing through nitrogen gas and reacted at 10 ° C for 7 hours to obtain 10wt% polyamic acid solution. The results are shown in Tables 1 to 3 below.

Example 5

HTD-4-DAB (0.76g, 2mmole) in solid form of Chemical Formula 9 was added to 11.79g of reaction solvent while slowly passing nitrogen gas through a 50mL reactor equipped with a stirrer, temperature controller, nitrogen injector, dropping funnel and cooler. After dissolving, BODA (0.25g, 1mmole) and BTDA (0.32g, 1mmole) were slowly added while passing through nitrogen gas and reacted at 10 ° C for 7 hours to obtain a 10wt% polyamic acid solution. Are shown in Tables 1 to 3 below.

Example 6

HTD-2-DAB (0.76 g, 2mmole) in solid form of Chemical Formula 10 was added to 11.79 g of reaction solvent while slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, temperature controller, nitrogen injector, dropping funnel and cooler. After dissolving, BODA (0.25g, 1mmole) and BTDA (0.32g, 1mmole) were slowly added while passing through nitrogen gas and reacted at 10 ° C for 7 hours to obtain a 10wt% polyamic acid solution. Are shown in Tables 1 to 3 below.

Example 7

While slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, a temperature controller, a nitrogen injector, a dropping funnel, and a cooler, solid DMD-4-DAB (0.84 g, 2 mmoles) of Formula 11 was added to 13.14 g of reaction solvent DMAc. After dissolving, BTDA (0.64g, 2mmole) was slowly added while passing through nitrogen gas, and reacted at 10 ° C. for 7 hours to obtain a 10wt% polyamic acid solution, and the overall physical properties thereof were evaluated in Tables 1 to 3 below. Indicated.

Example 8

DMD-4-DAB (0.42g, 1mmole) and p-PDA (0.11g) in solid phase of Formula 11 while slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, temperature controller, nitrogen injector, dropping funnel and cooler. , 1mmole) was dissolved in 11.79g of the reaction solvent DMAc and then slowly added ODPA (0.31g, 1mmole) and BTDA (0.32g, 1mmole) while passing through nitrogen gas. A polyamic acid solution was obtained and the physical properties thereof were evaluated, and the results are shown in Tables 1 to 3 below.

Example 9

DMD-4-DAB (0.08g, 0.2mmole) and p-PDA (0.20) in solid phase of Formula 11 while slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, temperature controller, nitrogen injector, dropping funnel and cooler. g, 1.8mmole) was dissolved in 11.79g of the reaction solvent DMAc, and DOCDA (0.53g, 2mmole) was slowly added while passing through nitrogen gas to react at 10 ° C for 7 hours to obtain a 10wt% polyamic acid solution. The results are shown in Tables 1 to 3 below.

Example 10

HTD-4-DAB (0.61g, 1.6mmole) and ODA (0.08g, solid phase) of Formula 9 while slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, temperature controller, nitrogen injector, dropping funnel and cooler 0.4mmole) was dissolved in 11.79g of reaction solvent DMAc, and DOCDA (0.53g, 2mmole) was slowly added while passing through nitrogen gas to react at 10 ° C for 7 hours to obtain 10wt% polyamic acid solution. The results are shown in Tables 1 to 3 below.

Example 11

HTD-4-DAB (0.03g, 0.2mmole) and p-PDA (0.18g) in solid phase of Formula 9 while slowly passing nitrogen gas through a 50 mL reactor equipped with a stirrer, temperature controller, nitrogen injector, dropping funnel and cooler. g, 1.6 mmol) and SDA (0.05 g, 0.2 mmol) were dissolved in 11.79 g of the reaction solvent DMAc, and DOCDA (0.53 g, 2 mmol) was slowly added while passing through nitrogen gas to react at 10 ° C. for 7 hours to obtain 10 wt% of A polyamic acid solution was obtained and the physical properties thereof were evaluated, and the results are shown in Tables 1 to 3 below.

Comparative Example 1

Except for reacting BAPP (0.82g, 2mmole) instead of EG-3-DAB (0.62g, 2mmole) was carried out in the same manner as in Example 1 to synthesize a polyamic acid and evaluate the overall physical properties to the results It is shown together in Tables 1-3.

Comparative Example 2

Except for reacting ODA (0.40g, 2mmole) in place of EG-3-DAB (0.62g, 2mmole) was carried out in the same manner as in Example 1 to synthesize a polyamic acid and evaluate the overall properties of the results It is shown together in Tables 1-3.

Comparative Example 3

Except for reacting ODA (0.40g, 2mmole) instead of BTD-3-DAB (0.68g, 2mmole) was carried out in the same manner as in Example 3 to synthesize a polyamic acid and evaluated the overall physical properties It is shown together in Table 1 to Table 3 below.

[Property evaluation]

The physical properties of the polyamic acid, the polyimide resin and the liquid crystal display device obtained in this example were evaluated by the following method.

(1) Intrinsic viscosity of polyamic acid and glass transition temperature (Tg) of polyimide resin

The intrinsic viscosity of the polyamic acid was measured at 30 ° C. at a concentration of 0.5 dL / g using NMP as a solvent, and the glass transition temperature was measured using a differential scanning calorimeter (DSC).

Intrinsic viscosity of polyamic acid (dl / g) Tg of polyimide (℃) Example 1 0.95 178 Example 2 0.79 138 Example 3 0.52 148 Example 4 0.65 205 Example 5 0.35 184 Example 6 0.28 170 Example 7 0.99 173 Example 8 0.80 225 Example 9 0.45 265 Example 10 0.48 200 Example 11 0.40 255 Comparative Example 1 0.97 242 Comparative Example 2 1.05 270 Comparative Example 3 0.76 265

From the viscosity of the polyamic acid obtained in the above example, it can be seen that all polymers of high molecular weight are synthesized except when the amine is substituted with ortho. The Tg of the polyimide obtained by completely curing the synthesized polyamic acid showed various values depending on the structure. In particular, the longer the alkyl group in the amine synthesized in the present invention, the lower the Tg. Also, the substitution position of amine showed the highest Tg when para.

(2) Printability and liquid crystal alignment characteristic

The polyamic acid solution obtained in the above example was added with gamma -butyrolactone so that the solid content was 5wt%. It was a thin film coating (speed: 700rpm / 5sec-1700rpm / 30sec) on an ITO glass substrate, baked at 180 ° C, 230 ° C, and 250 ° C temperature to investigate the printability, and was formed by rubbing the formed polyimide film. The orientation characteristic of was evaluated and put together in following Table 2. At this time, the alignment state of the liquid crystal was observed using a polarizing microscope, and the pretilt angles of the respective liquid crystal cells were measured using the crystal rotation method.

Pretilt angle according to curing temperature Printability Liquid crystal orientation 180 ℃ 230 ℃ 250 ℃ Example 1 2.15 2.20 2.21 Great Great Example 2 6.85 6.87 6.88 Great Great Example 3 2.70 2.73 2.74 Great Great Example 4 2.65 2.66 2.67 Great Great Example 5 4.01 4.04 4.05 usually Great Example 6 4.56 4.57 4.57 usually Great Example 7 7.11 7.12 7.13 Great Great Example 8 7.05 7.25 7.30 Great Great Example 9 4.09 4.39 4.80 Great Great Example 10 4.32 4.49 4.51 Great Great Example 11 3.21 3.51 3.94 Great Great Comparative Example 1 1.47 1.83 2.20 usually Bad Comparative Example 2 0.52 0.69 0.84 Bad Bad Comparative Example 3 1.32 1.59 1.98 Great Bad

(3) Voltage retention rate

In the liquid crystal cell, one ITO glass plate electrode is connected to the drain of the TFT module, while the other ITO glass plate electrode is grounded, and a frequency of 30 Hz and a voltage of ± 4.5 V are signaled in a signal of 100 μs period to change the voltage of the drain to 180 ° C. 230 ℃, and was measured by changing to 250 ℃ summarized in Table 3 below. Voltage retention is defined as in Equation 1 below.

Voltage retention according to curing temperature 180 ℃ 230 ℃ 250 ℃ Example 1 93.8 95.4 94.9 Example 2 90.0 90.5 90.9 Example 3 91.5 93.8 92.9 Example 4 92.8 93.1 93.3 Example 5 94.0 95.6 96.1 Example 6 65.8 72.5 79.5 Example 7 98.0 98.5 99.1 Example 8 97.0 97.2 98.5 Example 9 96.7 96.5 97.2 Example 10 93.8 94.5 96.5 Example 11 80.1 89.2 92.1 Comparative Example 1 45.8 49.1 53.0 Comparative Example 2 32.5 42.2 55.3 Comparative Example 3 50.2 58.2 65.2

As confirmed through Table 3, when using an aromatic diamine having an aliphatic carbon component in the main chain characteristically used in the present invention exhibited a high voltage retention of 92% or more. In particular, the larger the value of the alkyl group n in the formula (1) was shown to be excellent voltage retention.

The polyimide resin of the present invention can be applied to liquid crystal display devices such as STN-LCDs because it is excellent in printability, transparency, molding and processability, and can be applied as a liquid crystal alignment film that exhibits high pretilt angle regardless of curing conditions. Further, since the liquid crystal display device manufactured by the polyamic acid or polyimide resin of the present invention has excellent liquid crystal orientation and reliability, it can be used in wall-mounted liquid crystal TVs, computers, word processors, and the like.

Claims (10)

A polyamic acid resin comprising a repeating unit of formula (4) prepared by polymerizing an aromatic diamine having an aliphatic carbon component and tetracarboxylic dianhydride in a main chain represented by formula (1). [Formula 1] Wherein n is an integer between 2-16, The position of the diamine is the position of one of ortho, para and meta. [Formula 4] Where Is a tetracarboxylic dianhydride component; Is a diamine component; n is an integer between 2 and 16. The tetracarboxylic dianhydride monomer of claim 1 The polyamic acid resin, characterized in that at least one member selected from the group of the formula (3). [Formula 3] According to claim 1, Diamine monomer of the formula (4), In addition to the diamine of the general formula (1), polyamic acid resin comprising a repeating unit which is at least one diamine selected from the group of the formula (2). [Formula 2] 4. The polyamic acid resin according to claim 3, wherein the molar ratio of the aromatic diamine component of Chemical Formula 1 is 5 to 100 mol% with respect to all the diamine components. A polyimide resin prepared by curing the polyamic acid of claim 1 and having a repeating unit represented by the following Chemical Formula 5. [Formula 5] Where Is a tetracarboxylic dianhydride monomer; Is a diamine monomer. The tetracarboxylic dianhydride monomer of claim 5 The polyimide resin, characterized in that at least one member selected from the group of formula (3). [Formula 3] According to claim 5, Diamine monomer of the formula (5), A polyimide resin comprising a repeating unit which is one or more diamines selected from the group of the following Chemical Formula 2 in addition to the diamine of Chemical Formula 1. [Formula 2] The polyimide resin according to claim 7, wherein the molar ratio of the aromatic diamine component of Chemical Formula 1 is 5 to 100 mol% based on the total diamine components. The liquid crystal aligning film manufactured from the polyimide resin of Claim 5. The liquid crystal display device which mounted the liquid crystal aligning film of Claim 9 on the surface of both the upper and lower board | substrates.