KR101277291B1 - Composition for liquid crystal aligning, liquid crystal aligning film manufactured by the same, and liquid crystal display comprising the same - Google Patents

Abstract

The present invention relates to a liquid crystal display composition, a liquid crystal alignment film prepared therefrom, a method for manufacturing the same, and a liquid crystal display including the liquid crystal alignment film.

The liquid crystal alignment film prepared from the liquid crystal alignment composition according to the present invention not only exhibits an excellent alignment state, but also excellent electrical characteristics such as voltage holding characteristics.

Polyamic acid, polyimide, diamine structure, liquid crystal alignment film

Description

Composition for liquid crystal alignment, liquid crystal alignment film prepared therefrom, and a liquid crystal display including the same.

The present invention relates to a liquid crystal display composition, a liquid crystal alignment film prepared therefrom, a method for manufacturing the same, and a liquid crystal display including the liquid crystal alignment film.

With the development of the display industry, liquid crystal displays provide low driving voltage, high resolution, reduction of monitor volume, and flattening of monitors.

In general, liquid crystal displays induce anisotropy by applying an organic film such as polyimide to two glass substrates and rubbing the surface with a cloth (rubbing), bonding the two substrates in a sandwich form, and then injecting liquid crystals and heat treatment. It is manufactured by. Typical alignment films are made of a mixture or monocomponent of polyamic acid or polyimide.

One of the important properties usually required in the alignment film is the VHR characteristic of how well the voltage in the liquid crystal cell is maintained when driving the liquid crystal by voltage application and the amount of residual accumulated charge in the cell. If the electrical characteristics are not good, the display image of the liquid crystal display device may be distorted and become poor.

Therefore, there is a need for continuous research on liquid crystal alignment compositions having excellent electrical characteristics such as voltage holding characteristics.

The present invention is to solve the problems of the prior art as described above, the object of the present invention is not only to show an excellent alignment state, but also excellent electrical properties such as voltage holding characteristics, the liquid crystal alignment composition, a liquid crystal alignment film prepared therefrom, It is to provide a liquid crystal display device comprising the manufacturing method and the liquid crystal alignment film thereof.

One aspect of the present invention for achieving the above object provides a polyamic acid comprising a repeating unit represented by the following formula (1).

[Formula 1]

Where n is an integer from 5 to 200,

A represents a tetravalent organic group,

B represents a divalent organic group, includes a group represented by the following formula (2),

[Formula 2]

R in Formula 2 is hydrogen; C ₆ substituted or unsubstituted with one or more selected from the group consisting of a C _1-40 alkyl group, an ether group, an ester group, a C _1-40 alkyl group and a cholester group, unsubstituted or substituted with a halogen or a fluorine atom A cycloalkyl group of _-20 ; C ₆ substituted or unsubstituted with one or more selected from the group consisting of a C _1-40 alkyl group, an ether group, an ester group, a C _1-40 alkyl group and a cholester group, unsubstituted or substituted with a halogen or a fluorine atom An aryl group of _-20 ; Substituted or unsubstituted with _{one or more selected from} the group consisting of C _1-40 alkyl group, ether group, ester group, C _1-40 alkyl group, ketone group, and cholester group, unsubstituted or substituted with halogen or fluorine atom C _4-20 heterocycloalkyl group having hetero atoms as O, N or S; And substituted or unsubstituted with _{one or more selected from} the group consisting of a C _1-40 alkyl group, an ether group, an ester group, a C _1-40 alkyl group, a ketone group, and a cholester group, unsubstituted or substituted with a halogen or a fluorine atom. Ring and selected from the group consisting of C _4-20 heteroaryl groups having O, N or S as hetero atoms.

A second aspect of the present invention for achieving the above object provides a polyimide comprising a repeating unit represented by the following formula (7).

[Formula 7]

Where n is an integer from 5 to 200,

D and E are the same as the description of A and B of Formula 1, respectively.

A third aspect of the present invention for achieving the above object provides a composition for liquid crystal alignment comprising a polyamic acid comprising a repeating unit represented by the formula (1).

A fourth aspect of the present invention for achieving the above object, provides a composition for liquid crystal alignment comprising a polyimide comprising a repeating unit represented by the formula (7).

The fifth aspect of the present invention for achieving the above object is, by coating the liquid crystal alignment composition on the substrate surface to form a coating film, drying the solvent contained in the coating film, and rubbing on the dried coating film surface It provides a method for producing a liquid crystal alignment film comprising the step of alignment treatment.

A sixth aspect of the present invention for achieving the above object, provides a liquid crystal alignment film comprising the composition for liquid crystal alignment.

A seventh aspect of the present invention for achieving the above object, provides a liquid crystal display comprising the liquid crystal alignment film.

The liquid crystal alignment composition and the liquid crystal alignment film prepared therefrom of the present invention not only exhibit excellent alignment states, but also excellent electrical characteristics such as voltage holding characteristics.

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

One aspect of the invention relates to a polyamic acid comprising a repeating unit represented by the following formula (1).

[Formula 1]

In Formula 1,

n is an integer from 5 to 200,

A represents a tetravalent organic group,

B represents a divalent organic group and includes group represented by following formula (2).

 [Formula 2]

R in Formula 2 is as described above.

In particular, R of Formula 2 is preferably selected from the group consisting of Formula 3 to Formula 6.

[Formula 3] [Formula 4]

[Formula 5] [Formula 6]

Here, m and m 'are each independently an integer of 0 or 1, Y is independently C _1-40 alkyl group, ether group, ester group, amide group unsubstituted or substituted with hydrogen, halogen, fluorine atom It may be selected from the group consisting of _1-40 alkyl group, ketone group and cholester group.

In Formula 1, A is preferably selected from the group consisting of the following structural formulas.

Wherein Y ₁ and Y ₂ are each independently a direct bond, —O—, —CO—, —S—, —SO ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, -CONH,-(CH ₂ ) n _1- , -O (CH ₂ ) n ₂ O- and -COO (CH ₂ ) n ₃ OCO-, wherein n ₁ , n ₂ and n ₃ are each Independently an integer of 1 to 5.

The polyamic acid including the repeating unit represented by Formula 1 may be represented by the following Formula 1-1.

[Formula 1-1]

here,

A is as defined in A of Formula 1,

B is as defined in B of Formula 1,

B 'is selected from the group consisting of the following structural formulas,

N is 10 mol% or more and less than 100 mol%,

M is greater than 0 mol% and less than 90 mol%,

here,

R1 and R2 are independently of each other hydrogen, CH ₃ , OCH ₃ or CF ₃ ,

Q1 and Q2 may be simultaneously or each independently of —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —, —C (CH ₃ ) ₂ — or —C (CF ₃ ) _2- .

The second aspect of the present invention relates to a polyimide comprising a repeating unit represented by the following formula (7).

[Formula 7]

Where n is an integer from 5 to 200,

D represents a tetravalent organic group,

E represents a divalent organic group and includes the group represented by the said Formula (2).

D in Formula 7 is the same as defined for A in Formula 1.

The polyamic acid including the repeating unit represented by Formula 7 may be represented by the following Formula 7-1.

[Formula 7-1]

here,

D is the same as defined for A in Formula 7,

E is the same as defined for E in Formula 7,

E 'is selected from the group consisting of

N is 10 mol% or more and less than 100 mol%,

M is greater than 0 mol% and less than 90 mol%,

here,

R1 and R2 are independently of each other hydrogen, CH ₃ , OCH ₃ or CF ₃ ,

Q1 and Q2 may be simultaneously or each independently of —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —, —C (CH ₃ ) ₂ — or —C (CF ₃ ) _2- .

The polyimide containing the repeating units represented by Formula 7 and Formula 7-1 may be prepared by imidizing a polyamic acid including the repeating units represented by Formula 1 and Formula 1-1, respectively.

By adding an acetic anhydride and a pyridine base to the polyamic acid solution by imidizing the polyamic acid, and then heated to a temperature of 50 to 100 ℃ imidized by a chemical reaction, or by applying a polyamic acid solution to the substrate, Thermal imidation may be performed on an oven or a hot plate at 100 ° C. to 250 ° C., but is not limited thereto.

The number average molecular weight (Mn) of the polyamic acid or polyimide according to the present invention is preferably 5,000 to 500,000 g / mol. If the molecular weight of the polyamic acid or polyimide is less than 5,000 g / mol coating property is poor, if it exceeds 500,000 g / mol it may be difficult to implement a stable coating process because the viscosity is too high when preparing the coating solution.

Polyamic acid containing a repeating unit represented by the formula (1) or a polyimide containing a repeating unit represented by the formula (7) according to the present invention is a dianhydride compound represented by the formula (8) and diamine represented by the formula (9) It can be prepared from a compound. Other reaction conditions may use methods known in the art.

[Chemical Formula 8]

In Formula 9, R is the same as defined in Formula 2.

In addition, the method for producing a polyamic acid containing a repeating unit of Formula 1-1 or a polyimide comprising a repeating unit of Formula 7-1 may be represented by the dianhydride compound represented by Formula 8 and Formula 9 In addition to the diamine compound, it may be prepared by further adding another kind of diamine compound.

It is preferable to use 1 or more types chosen from the group which consists of a structural formula as said another kind of diamine compound.

here,

R1 and R2 are independently of each other hydrogen, CH ₃ , OCH ₃ or CF _3, etc.,

Q1 and Q2 may be simultaneously or each independently of —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —, —C (CH ₃ ) ₂ — or —C (CF ₃ ) ₂ -and so on.

When the polyamic acid or polyimide is prepared by using another diamine compound other than the diamine compound represented by the formula (9), the content of the diamine compound further included other than the compound represented by the formula (9) is added in total. It is preferable to contain more than 0 mol% and less than 90 mol% with respect to the diamine compound to become.

When the molar ratio of the diamine compound represented by the formula (9) is less than 10 mol%, the alignment characteristics, the voltage holding characteristics, and the like of the prepared liquid crystal alignment layer may be deteriorated.

 Specifically, the method for producing a polyamic acid or polyimide according to the present invention dissolves a diamine compound represented by Formula 9 or a diamine compound different from the diamine compound represented by Formula 9 in a solvent, and the formula It can manufacture by adding and reacting 1 or more types of the dianhydride compound represented by 8. The reaction of the diamine compound and dianhydride compound is preferably carried out at 0 to 25 ℃ for 24 hours. At this time, it is advantageous to mix the dianhydride compound and the diamine compound in a molar ratio of 1: 0.7 to 1: 1.3 to achieve desirable molecular weight, mechanical properties and viscosity.

The third aspect of the present invention relates to a liquid crystal alignment composition comprising a polyamic acid comprising a repeating unit represented by the formula (1).

A fourth aspect of the present invention relates to a liquid crystal alignment composition comprising a polyimide containing a repeating unit represented by the formula (7).

The composition for liquid crystal alignment according to the present invention may be prepared by dissolving at least one of a polyamic acid including a repeating unit represented by Formula 1 or a polyimide including a repeating unit represented by Formula 7 in a solvent.

The solid content concentration of the polyamic acid or polyimide is selected in consideration of the molecular weight, viscosity, volatility, and the like of the polyamic acid or polyimide including the repeating unit represented by Formula 1 or Formula 7, to achieve a desired liquid crystal alignment effect, In order to have a suitable viscosity to have the desired coating properties, it is preferable to select within the range of 1 to 20% by weight based on the total weight of the liquid crystal alignment composition.

The solvent may include cyclopentanone, cyclohexanone, N-methylpyrrolidone, dimethylformamide (DMF), acetamide, gamma butyrolactone, or a mixture thereof, but is not limited thereto. .

In addition, solvents such as 2-butoxyethanol, ethylene glycol monoethyl ether acetate, ethylene glycol monoisopropyl ether, and ethylene glycol monomethyl ether in order to prevent film thickness uniformity and printing defects after coating treatment Can be used in combination with the solvents exemplified above.

The temperature at which the polyamic acid or polyimide is dissolved in a solvent is 0 to 100 ° C, more preferably 15 to 70 ° C.

The liquid crystal alignment composition according to the present invention may include conventional solvents, additives, polyimides, and polyamic acids known in the art.

The fifth aspect of the invention

1) coating the liquid crystal alignment composition on the surface of the substrate to form a coating film,

2) drying the solvent contained in the coating film, and

3) rubbing on the dried coating surface to perform alignment treatment

It relates to a method for producing a liquid crystal alignment film comprising a.

A sixth aspect of the present invention relates to a liquid crystal alignment film including the liquid crystal alignment composition.

The composition for liquid crystal alignment of step 1) may be applied onto the surface of the substrate formed by patterning a transparent conductive film or a metal electrode using a method such as a roll coater method, a spinner method, a printing method, an inkjet spraying method, or a slit nozzle method. .

In addition, in order to further improve the adhesiveness of the surface of a board | substrate, a transparent conductive film, a metal electrode, and a coating film, when apply | coating the composition for liquid crystal aligning, a functional silane containing compound, a functional fluoro containing compound, and a functional titanium containing compound are previously made. It may apply to a board | substrate.

In the step 2), the drying may be performed by heating the coating or vacuum evaporation.

In the step 2), the drying of the solvent is carried out for 10 to 60 minutes at 100 to 300 ℃, preferably 170 to 250 ℃ in the case of a liquid crystal alignment composition comprising a polyamic acid and at the same time to imidize the polyamic acid It may be dried, and in the case of a liquid crystal alignment composition including polyimide, it may be performed at 100 to 300 ° C., preferably at 170 to 230 ° C. for 10 to 60 minutes.

In step 3), an alignment capability for aligning the liquid crystal molecules by physically contacting the rubbing fibers such as nylon or rayon to the dried coating film obtained in step 2) can be imparted to the coating film.

It is preferable that the film thickness of the final coating film formed by the above series of processes is 50-200 nm, and in order to play a role in a display apparatus, the range of 70-150 nm is more preferable.

After the above-described process, it is possible to obtain a liquid crystal alignment layer having a liquid crystal alignment ability stable to external thermal, physical, and chemical impact.

A seventh aspect of the present invention relates to a liquid crystal display including the liquid crystal alignment layer.

The liquid crystal display may be manufactured according to conventional methods known in the art. For one embodiment thereof, one of the two glass substrates with the photoreaction with the liquid crystal alignment film according to the present invention is applied to the end of the glass substrate with a photoreactive adhesive containing a ball spacer at the end of the glass substrate The glass substrates are bonded together, and only the portion to which the adhesive is applied is irradiated with ultraviolet rays to bond the cells. After the liquid crystal is injected into the completed cell and heat treated, the liquid crystal cell is completed.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

Manufacturing example

The DA-TPNR according to the present invention was prepared according to the following reaction sequence.

Production Example 1 : Synthesis of 4,4'-Diamino-4 "-dodecyloxytriphenylamine (4,4'-Diamino-4"-dodecyloxytriphenylamine, DA-TPNpO12) monomer

69.5 g (0.5 mol) of 4-nitrophenol and 137 g (0.55 g) of dodecyl bromide were dissolved in 250 ml of DMF. Then, 138 g (1 mole) of potassium carbonate (K2CO3) was added, and the reaction temperature was raised to 60 degrees and stirred for 6 hours. After the reaction was cooled to room temperature, the residue was filtered off and the remaining solution was concentrated under reduced pressure. The concentrated residue was purified by recrystallization under methanol to give 146 g of 4- (dodecyloxy) nitrobenzene at 95% yield. 146 g (0.48 mol) of 4- (dodecyloxy) nitrobenzene obtained was dissolved in 600 ml of THF and 300 ml of isopropanol (IPA), and then 5 g of a 5% palladium on charchol catalyst was added, followed by hydrogen in a high pressure hydrogen reactor. The reaction was carried out at a pressure of 100 psi for 24 hours. The reaction product was removed using a cellite filter (cellite) and the resulting solution was concentrated under reduced pressure. The concentrated reaction was recrystallized using an n-hexane solvent to give 113 g of 4- (dodecyloxy) aniline at a yield of 86%. After dissolving 13.85 g (50 mmol) of 4- (dodecyloxy) aniline in 50 ml of DMSO, 28.g (200 mmol) of 4-fluoronitrobenzene and 30.4 g (200 mmol) of CsF were added thereto, and the temperature was increased to 120 ° C. Stir for 48 hours. The reaction was then cooled to room temperature and added to excess water to give a precipitate. The resulting precipitate was filtered off, washed with water and methane and dried to give 24.7 g of 4,4'-dinitro-4 "-dodecyloxytriphenylamine in 95% yield. 24.3 g (47 mmol) of -dinitro-4 "-dodecyloxytriphenylamine was dissolved in 200 ml of THF and 100 ml of isopropanol (IPA), followed by addition of 2 g of a 5% palladium on charchol catalyst. The reaction was carried out at 100 psi of hydrogen pressure for 24 hours. The reaction product was removed using a cellite filter (cellite) filter and the resulting solution was concentrated under reduced pressure. The concentrated reaction was recrystallized using a cooled n-hexane solvent to give 19.2 g of 4,4'-diamino-4 "-dodecyloxytriphenylamine in 89% yield.

DA-TPNpO12 was confirmed using a hydrogen nuclear magnetic resonance spectrometer.

¹ H NMR (500 MHz, DMSO-d ₆ ): 6.76-6.68 (m, 8H), 6.51 (d, 4H), 4.87 (s, 4H), 3.87 (t, 2H), 1.69 (m, 2H), 1.41 (m, 2H), 1.35-1.25 (m, 16H), 0.89 (t, 3H)

Preparation Example 2 Synthesis of 4,4'-Diamino-3 "-dodecyloxytriphenylamine (4,4'-Diamino-3" -dodecyloxytriphenylamine, DA-TPNmO12) Monomer

4,4'-diamino-3 "-dode using the same method as in Preparation Example 1, except for using the same molar number of 3-nitrophenol instead of 4-nitrophenol during the preparation of Preparation Example 1. Siloxytriphenylamine was prepared.

The obtained DA-TPNmO12 was confirmed using a hydrogen nuclear magnetic resonance spectrometer.

¹ H NMR (500 MHz, DMSO-d ₆ ): 6.92 (t, 1H), 6.79 (d, 4H), 6.52 (d, 4H), 6.21 (dd, 1H), 6.14 (dd, 1H), 6.05 ( m, 1H), 4.97 (s, 4H), 3.75 (t, 2H), 1.60 (m, 2H), 1.32 (m, 2H), 1.30-1.15 (m, 16H), 0.85 (t, 3H)

Production Example 3 Synthesis of 4,4'-Diamino-4 "-dodecyltriphenylamine, DA-TPNp12 Monomer

Except for using 4- (1'-dodekenyl) nitrophenol instead of 4- (dodecyloxy) nitrobenzene in the preparation process of Preparation Example 1 using the same method as Preparation Example 1 4,4'-dia Mino-4 "-dodecyltriphenylamine was prepared.

Obtained DA-TPNp12 was confirmed using the hydrogen-nuclear magnetic resonance spectrometer.

¹ H NMR (500 MHz, DMSO-d ₆ ): 6.88-6.65 (m, 4H), 6.55-6.45 (m, 8H), 4.99 (s, 4H), 2.41 (t, 2H), 1.48 (m, 2H ), 1.32, 1.35-1.18 (m, 18H), 0.85 (t, 3H)

Production Example 4 : Synthesis of 4,4'-Diamino-4 "-tetradecyloxytriphenylamine (4,4'-Diamino-4" -tetradecyloxytriphenylamine, DA-TPNpO14) monomer

4,4'-diamino-4 "-tetradecyloxy was prepared in the same manner as in Preparation Example 1, except that tetradecylbrom in the same mole number was used instead of dodecyl bromide in Preparation Example 1. Triphenylamine was prepared.

The obtained DA-TPNpO14 was confirmed using a hydrogen nuclear magnetic resonance spectrometer.

¹ H NMR (500 MHz, DMSO-d ₆ ): 6.77-6.68 (m, 8H), 6.51 (d, 4H), 4.87 (s, 4H), 3.88 (t, 2H), 1.68 (m, 2H), 1.42 (m, 2H), 1.38-1.23 (m, 20H), 0.86 (t, 3H)

Example

Example 1 : Preparation of Polyamic Acid Resin (LPA-1) and Liquid Crystal Alignment Composition

5.31 g (26.8 mmol) of methylene diamine and 5.27 g (11.5 mmol) of DA-TPNpO12 were dissolved in NMP 104 g at room temperature, followed by 3.75 g (19.1 mmol) of cyclobutanetetracarboxylic dianhydride (CBDA) and pyromellitic dianhydride. 4.17 g (19.1 mmol) was added thereto and stirred at room temperature for 12 hours to prepare a polyamic acid resin (LPA-1).

NMP 127 g and 58 g 2-butoxyethanol were added to and diluted with the obtained polyamic acid resin (LPA-1), and then passed through a 0.2 mm filter to remove impurities to prepare a composition for liquid crystal alignment. .

As a result of confirming the molecular weight of the polyamic acid resin (LPA-1) through GPC, the number average molecular weight (Mn) was 25,000, the weight average molecular weight (Mw) was 60,000.

Example 2 : Preparation of Polyamic Acid Resin (LPA-2) and Liquid Crystal Alignment Composition

A liquid crystal alignment composition was prepared in the same manner as in Example 1, except that 5.27 g (11.5 mmol) of DA-TPNmO12 was used instead of 5.27 g (11.5 mmol) of DA-TPNpO12 to prepare a polyamic acid resin (LPA-2). .

As a result of confirming molecular weight of the polyamic acid resin (LPA-2) through GPC, the number average molecular weight (Mn) was 24,000, and the weight average molecular weight (Mw) was 55,000.

Example 3 : Preparation of polyamic acid resin (LPA-3) resin and liquid crystal alignment composition

A liquid crystal alignment composition was prepared in the same manner as in Example 1, except that polyamic acid resin (LPA-3) was prepared using 5.09 g (11.5 mmol) of DA-TPNp12 instead of 5.27 g (11.5 mmol) of DA-TPNpO12. .

As a result of checking the molecular weight of the polyamic acid resin (LPA-3) through GPC, the number average molecular weight (Mn) was 30,000, and the weight average molecular weight (Mw) was 63,000.

Example 4 : Preparation of polyamic acid resin (LPA-4) resin and liquid crystal alignment composition

A liquid crystal alignment composition was manufactured in the same manner as in Example 1, except that 5.59 g (11.5 mmol) of DA-TPNpO14 was used instead of 5.27 g (11.5 mmol) of DA-TPNpO12 to prepare a polyamic acid resin (LPA-4). .

As a result of confirming the molecular weight of the polyamic acid resin (LPA-4) through GPC, the number average molecular weight (Mn) was 28,000, the weight average molecular weight (Mw) was 55,000.

Example 5 : Preparation of Polyimide Resin (LPI-5) and Liquid Crystal Alignment Composition

To 40 g of polyamic acid resin (LPA-1) prepared in Example 1, 40 g of NMP, 2.4 g of pyridine and 4.3 g of acetic anhydride were added, followed by imidization reaction at 60 ° C. for 5 hours. Let. Thereafter, the precipitate was added dropwise to 2 L of excess methanol to form a precipitate. The precipitate was washed with methanol and dried under reduced pressure in an oven at 50 ° C. to prepare a polyimide resin (LPI-5).

44 g of NMP and 39 g of 2-butoxyethanol were added and diluted to the obtained polyimide resin (LPI-4), and then passed through a 0.2 mm filter to remove impurities to prepare a composition for liquid crystal alignment. .

The polyimide resin (LPI-4) was found to have a molecular weight through GPC, the number average molecular weight (Mn) was 18,000, the weight average molecular weight (Mw) was 35,000.

Comparative example

Comparative Example 1 : Preparation of Polyamic Acid Resin (RPA-1) and Preparation of Liquid Crystal Alignment Composition

Liquid crystal alignment composition in the same manner as in Example 1 except that polyamic acid resin (RPA-1) was prepared using 1.22 g (11.5 mmol) of p-phenylenediamine instead of 5.27 g (11.5 mmol) of DA-TPNpO12. Was prepared. .

The polyamic acid resin (RPA-1) was found to have a molecular weight through GPC, the number average molecular weight (Mn) was 23,000, the weight average molecular weight (Mw) was 42,000.

Comparative Example 2 : Preparation of Polyamic Acid Resin (RPA-2) and Liquid Crystal Alignment Composition

Polyamic acid resin using 3.68 g (11.5 mmol) of n-dodecyl-3,5-diaminobenzoate instead of 5.27 g (11.5 mmol) of DA-TPNpO12 in Example 1 A liquid crystal aligning composition was prepared in the same manner except that (RPA-2) was prepared.

The polyamic acid resin (RPA-2) was found to have a molecular weight through GPC, the number average molecular weight (Mn) was 21,000, the weight average molecular weight (Mw) was 41,000.

Experimental Example

Liquid crystal alignment characteristics of the liquid crystal alignment composition prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were performed as follows. The liquid crystal alignment composition was spin-coated on an ITO glass substrate, and then heated at 100 ° C. for 2 minutes and at 230 ° C. for 60 minutes to obtain a polyimide thin film having a thickness of 70 to 100 nm, which was rubbed using a cylindrical roll wound with a rayon cloth. . After rubbing the two glass substrates are placed in parallel with each other in the rubbing direction, they are bonded together using a UV curing agent impregnated with a 4.5 mm ball space, and then a nematic liquid crystal is injected into the cell to form a liquid crystal cell. Prepared.

Cell orientation characteristic evaluation

The cell orientation characteristic was judged to be good if the obtained cell was not unbalanced in orientation through visual observation and polarization microscopy under a polarization system. The results are shown in Table 1 below.

Pre-tilt angle

In the pretilt angle measurement, the pretilt angle of the obtained liquid crystal cell was measured by a crystal rotation method. The results are shown in Table 1 below.

Electrical property evaluation

Electrical characteristics were evaluated by measuring the voltage holding ratio (VHR) using a Toyo instrument (model 6254). Voltage retention ratio was measured after applying a voltage of 5V, 60 Hz at room temperature and high temperature (100 ℃). The results are shown in Table 1 below.

 [Table 1]

Orientation resin Cell orientation Pretilt angle
(˚) VHR (%) Room temperature 100 ℃ Example 1 LPA-1 Good 4.2 98.8 89.9 Example 2 LPA-2 Good 5.1 99.1 88.0 Example 3 LPA-3 Good 3.8 99.3 88.5 Example 4 LPA-4 Good 6.2 98.9 87.9 Example 5 LPI-5 Good 4.9 99.2 90.0 Comparative Example 1 RPA-1 Good 1.2 98.9 80.5 Comparative Example 2 RPA-2 Good 3.9 94.1 72.6

As shown in Table 1, the alignment properties of all the liquid crystal alignment compositions used in the experiment were good. However, in the pretilt angle, Comparative Example 1 did not provide sufficient pretilt angle due to the absence of the side chain group as in the case of the present invention. It is somewhat inferior. In addition, Comparative Example 2 having a side chain structure similar to Examples 1 to 5 of the present invention shows a good tritilt angle, but exhibits a very weak characteristic not only at room temperature but especially at high temperature in electrical characteristics such as voltage retention. It was. On the other hand, Examples 1 to 5 of the present invention exhibit sufficient pretilt angles for use as a liquid crystal display device, and exhibit very excellent characteristics not only at room temperature but also at high temperature in the voltage holding characteristic.

Claims (22)

Polyamic acid containing a repeating unit represented by the formula 1-1: [Formula 1-1]

here, A is one tetravalent organic group selected from the group consisting of the following structural formulas,

Y ₁ and Y ₂ are each independently a direct bond, -O-, -CO-, -S-, -SO _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -CONH ,-(CH ₂ ) n _1- , -O (CH ₂ ) n ₂ O- and -COO (CH ₂ ) n ₃ OCO-, n ₁ , n ₂ and n ₃ are each independently Is an integer from 1 to 5, B is a divalent organic group represented by the following formula (2), [Formula 2]

R in Formula 2 is hydrogen; An alkyl group having 1 to 20 carbon atoms; And alkoxy group having 1 to 20 carbon atoms; selected from the group consisting of, B ′ is an alkylene group having 1 to 10 carbon atoms, or one divalent functional group selected from Chemical Formulas 1-11, N is 10 mol% or more and less than 100 mol%, M is greater than 0 mol% and less than 90 mol%, [Formula 1-11]

In Chemical Formula 1-11, R1 and R2 are independently of each other hydrogen, CH ₃ , OCH ₃ or CF ₃ , Q1 and Q2 may be simultaneously or each independently of —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —, —C (CH ₃ ) ₂ — or —C (CF ₃ ) _2- . delete delete delete The polyamic acid according to claim 1, wherein the polyamic acid has a number average molecular weight of 5,000 to 200,000 g / mol. Polyimide containing a repeating unit represented by the formula 7-1: [Formula 7-1]

here, D is one tetravalent organic group selected from the group consisting of

Y ₁ and Y ₂ are each independently a direct bond, -O-, -CO-, -S-, -SO _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -CONH ,-(CH ₂ ) n _1- , -O (CH ₂ ) n ₂ O- and -COO (CH ₂ ) n ₃ OCO-, n ₁ , n ₂ and n ₃ are each independently Is an integer from 1 to 5, E is a divalent organic group represented by the following formula (2),  [Formula 2]

R in Formula 2 is hydrogen; An alkyl group having 1 to 20 carbon atoms; And alkoxy group having 1 to 20 carbon atoms; selected from the group consisting of, E ′ is an alkylene group having 1 to 10 carbon atoms, or one divalent functional group selected from Chemical Formulas 1-11, N is 10 mol% or more and less than 100 mol%, M is greater than 0 mol% and less than 90 mol%,  [Formula 1-11]

here, R1 and R2 are independently of each other hydrogen, CH ₃ , OCH ₃ or CF ₃ , Q1 and Q2 may be simultaneously or each independently of —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —, —C (CH ₃ ) ₂ — or —C (CF ₃ ) _2- . delete delete delete The polyimide of claim 6, wherein the polyimide has a number average molecular weight of 5,000 to 200,000 g / mol. A composition for liquid crystal alignment comprising the polyamic acid of claim 1. The liquid crystal alignment composition of claim 11, wherein the solid content concentration of the polyamic acid is 1 to 20 wt% based on the total weight of the liquid crystal alignment composition. A composition for liquid crystal alignment comprising the polyimide of claim 6. The composition of claim 13, wherein the solid content concentration of the polyimide is 1 to 20 wt% based on the total weight of the liquid crystal alignment composition. 1) forming a coating film by applying the liquid crystal alignment composition of any one of claims 11 to 14 on the surface of the substrate, 2) drying the solvent contained in the coating film, and 3) rubbing on the dried coating surface to perform alignment treatment Method for producing a liquid crystal alignment film comprising a. A liquid crystal alignment film comprising a polyimide containing a repeating unit represented by the formula (7-1): [Formula 7-1]

here, D is one tetravalent organic group selected from the group consisting of

Y ₁ and Y ₂ are each independently a direct bond, -O-, -CO-, -S-, -SO _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -CONH ,-(CH ₂ ) n _1- , -O (CH ₂ ) n ₂ O- and -COO (CH ₂ ) n ₃ OCO-, n ₁ , n ₂ and n ₃ are each independently Is an integer from 1 to 5, E is a divalent organic group represented by the following formula (2),  [Formula 2]

R in Formula 2 is hydrogen; An alkyl group having 1 to 20 carbon atoms; And alkoxy group having 1 to 20 carbon atoms; selected from the group consisting of, E ′ is an alkylene group having 1 to 10 carbon atoms, or one divalent functional group selected from Chemical Formulas 1-11, N is 10 mol% or more and less than 100 mol%, M is greater than 0 mol% and less than 90 mol%, [Formula 1-11]

here, R1 and R2 are independently of each other hydrogen, CH ₃ , OCH ₃ or CF ₃ , Q1 and Q2 may be simultaneously or each independently of —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —, —C (CH ₃ ) ₂ — or —C (CF ₃ ) _2- . delete delete delete The liquid crystal aligning film of claim 16, wherein the polyimide has a number average molecular weight of 5,000 to 200,000 g / mol. The liquid crystal alignment film of claim 16, wherein the liquid crystal alignment film has a thickness of 50 to 200 nm. A liquid crystal display comprising the liquid crystal alignment film according to claim 16.