KR100536122B1 - Composition for photoinduced liquid crystal alignment having porous structure, the film for photoinduced liquid crystal alignment thereby, manufacturing method of the same and the liguid crystal cell comprising the film - Google Patents

Abstract

In the present invention, a liquid crystal aligning agent composition having a pore structure, a liquid crystal aligning film using the same, a manufacturing method thereof, and a liquid crystal device including the liquid crystal aligning film are disclosed. The present invention improves the electro-optical properties such as residual DC and VHR by improving problems such as high polarity and large dielectric constant of the conventional alignment agent, and also reduces voltage drop occurring along the signal line in the display, resulting in afterimage and flicker. It solves the phenomenon, makes it possible to apply to large-area display production, and achieves the effect of realizing high quality display quality.

Description

A liquid crystal aligning agent composition having a porous structure, a liquid crystal aligning film using the same, a method for manufacturing the same, and a liquid crystal device including the liquid crystal aligning film TECHNICAL FIELD THE SAME AND THE LIGUID CRYSTAL CELL COMPRISING THE FILM}

The present invention relates to a liquid crystal aligning agent composition having a porous structure, a liquid crystal aligning film using the same, a manufacturing method thereof, and a liquid crystal device including the liquid crystal aligning film.

In this invention, when a pore is formed and hold | maintained in the liquid crystal aligning film which has a liquid crystal aligning agent composition or a liquid crystal aligning agent composition, it means the structure containing the pore formed and hold | maintained in this way.

In the present invention, the bubble-forming substance refers to a substance or a polymer having many branches that can directly generate bubbles by heat.

The photosensitive polymer liquid crystal aligning agent of the present invention is used as a liquid crystal aligning agent of a device using optical properties. In general, a liquid crystal is oriented by applying an alignment agent on a substrate and irradiating ultraviolet light to the surface to form anisotropy on the surface thereof. Combinations and their constituent materials.

The liquid crystal device of the present invention is applied to various fields such as a liquid crystal display (LCD), a compensator and an optical part. In the present invention, in particular, the application to the liquid crystal display device (LCD) is mainly described, but is not limited thereto, and all applications within the scope encompassing the technical idea of the present invention are included.

The liquid crystal display device is leading the flat panel display market because it has the advantages of easy portability and low power consumption. As the usage is gradually expanded to applications such as calculator notebooks and wall-mounted TVs and high-definition TVs, high-definition, high-quality and optical Viewing angle is required.

Such liquid crystal display devices are generally filled with liquid crystals oriented between two glass substrates coated with an alignment layer, and rearrangement (switching) of liquid crystal molecules occurs by an electric field applied from the outside to form a desired image. In this case, in order to obtain uniform brightness and high contrast ratio, it is essential to orient the liquid crystal uniformly in a specific direction.

Currently, rubbing process and non-rubbing process, such as silicon oxide oblique deposition method, liquid crystal alignment induction method using ion beam, photo-alignment method and the like are known as a method of orienting the liquid crystal.

1 is a schematic view showing an alignment step of a liquid crystal alignment film by a conventional rubbing method.

In the rubbing method, as shown in FIG. 1, the rubbing drum 7 which apply | coated high molecular compounds, such as a polyimide, to the board | substrate 2 by the printing method etc., and wound the cloth which planted this surface into the nylon and polyester rayon fiber. It is a method of forming a very fine groove on the surface of the polymer by rubbing by rotating at a high speed.

While the rubbing process is carried out, the liquid crystal molecules are aligned with a constant pretilt angle (θ) on the surface of the alignment agent. This rubbing method is widely used industrially because the process is simple, large-area and high-speed treatment is possible.

However, the shape of the microgrooves formed in the alignment layer varies according to the friction strength between the alignment cloth and the alignment layer, resulting in non-uniform arrangement of liquid crystal molecules, resulting in phase distortion and light scattering. In addition, there is a problem in that the production yield is lowered by damage to the substrate 2 due to electrostatic discharge (ESD) generated by rubbing the polymer surface and fine dust generated in the rubbing drum 7.

In addition, in order to make a multi-domain display that widens the viewing angle by dividing one pixel into small pixels and changing the liquid crystal alignment state of each divided pixel, the alignment film coating, rubbing, coating of photoresist and exposure ( Complex lithographic processes such as exposure and development, rubbing, removal of photoresist, etc. are required, which is undesirable in terms of productivity.

On the other hand, as the non-rubbing method, the silicon oxide oblique direction deposition method is a method of depositing silicon oxide in an oblique direction with respect to a substrate, and it is difficult to maintain uniformity of deposition angle and film thickness with respect to the substrate, and the process is large in scale. There is a problem.

As a non-rubbing method, the photo-alignment method inclines or vertically irradiates linearly polarized ultraviolet light onto a substrate coated with a photosensitive polymer, and induces photo-dimerization or photo-isomerization. As a result, it is a method of non-contact treatment with respect to the orientation surface which forms anisotropy in a surface.

The possibility of this photoalignment method has been found using azobenzene compounds (K. lchimura et al., Langmuir, 4, 1214, 1988), followed by polymaleimide (HJChoi et al., US Patent 6218501), polyolefins (RH). Herr et al. US Patent 6201087) have been developed as photo-alignment materials.

In the photoalignment method using the liquid crystal aligning agent, the liquid crystal aligning agent has a certain direction with respect to the polarization direction of the linearly polarized ultraviolet light, which is determined by the structure of the photosensitive polymer used. In addition, the pretilt direction varies with the incident direction of irradiated ultraviolet rays, and the pretilt angle varies with the irradiation energy and the incident angle. As the polymer mainly used up to now, for example, there are some containing an ethene group having a photosensitive property. Examples of the photosensitive portion include chalcone, cinnamoyl, and coumarin.

A method of inducing liquid crystal alignment by using an ion beam as a non-rubbing method is a method of inducing liquid crystal alignment by applying an ion beam after applying a polymer aligning agent. An ion beam is an electromagnetic beam of gas molecules such as argon, helium, oxygen, and nitrogen. Method For example, it refers to a flow state of ions that are energized by applying an electron gun or ionizing using RF electromagnetic waves and applying a voltage of 100 to 3000 eV.

When the ion beam having the energy is irradiated on the surface of the polymer material, the surface atoms are scraped off and redeposited to form characteristic surface curvatures for each polymer. Surface curvature varies in shape and size depending on the type of ions to be irradiated, the energy, the amount of radiation, and the type of polymer, and ranges from a few nanometers to hundreds of micrometers. When the surface is curved has a certain direction, which acts as a micro groove by rubbing.

Since the liquid crystal alignment induction method using the optical alignment method or the ion beam is a non-contact method, problems due to the introduction of impurities and the generation of static electricity can be basically eliminated. Therefore, the cleanliness is maintained and the alignment process is easy to improve the yield and is suitable for mass production. It has advantages

In the case of the photo-alignment method, since the multi-domain can be formed by a relatively simple process of irradiating ultraviolet rays with different polarization directions depending on the region using the photomask, it is advantageous to improve the viewing angle.

However, the photo-alignment method or the method using the ion beam has a weak physical bonding force between the liquid crystal aligning agent formed with anisotropy and the liquid crystal, poor thermal mechanical stability such as weakening of the alignment due to heat, and satisfactory electro-optic properties. There is a limit to this.

In particular, in the device using the alignment agent, image sticking of the liquid crystal panel cannot be completely removed, flicker occurs, and a high voltage drop and a current loss occur. The strong current loss is due to the high dielectric constant of the polymer, and the afterimage or flicker phenomenon is known to be caused by the ions present in the liquid crystal cell electrically acting on the alignment layer, causing adsorption and desorption repeatedly.

Residual DC (direct current) and VHR (Voltage Holding Ratio), which are typical electro-optical characteristics measurement methods, are used as a criterion for determining afterimages. The lower the value, the better. The VHR evaluates the degree to which the pulse voltage is maintained when a pulse is supplied for one screen frame during display driving. The closer to 100%, the better.

In order to prevent high voltage drop and current loss, the dielectric constant should be lowered.

FIG. 2 is a schematic diagram showing the structure of a conventional liquid crystal element, and FIG. 3 is a circuit diagram showing the capacitance of the liquid crystal element of FIG.

As shown in FIG. 2, in the liquid crystal element 5 composed of an alignment film 1, a transparent electrode ITO 3, and a glass substrate 2 facing the liquid crystal layer 4 therein, the liquid crystal layer 4. When the capacitance of) is C _LC and the capacitance of the alignment layer 1 is C _A , as shown in FIG. 3, the capacitance of the entire device 5 is the same as when two capacitors are connected in series. In this case, the capacitance C _A of the alignment layer 1 is represented by C _A = εA / d with respect to the device area A, the thickness d, and the dielectric constant ε. Therefore, when the dielectric constant is large, the capacitance of the alignment layer 1 becomes large, and thus (5) The total capacitance becomes large, which causes more current to be supplied to drive the liquid crystal element and also increases the voltage drop in the element.

Therefore, in order to prevent voltage drop and current loss, it is necessary to lower the dielectric constant, and in the case of large-area display, it is more necessary.

In order to remove the afterimage or flicker phenomenon, the polarity of the polymer must be lowered because the electrical interaction with the ions can be reduced, so that the afterimage problem can be improved by lowering the residual DC value. This is because the VHR is maintained with less influence, thereby eliminating flicker that flickers.

However, in the case of polyimide, which is conventionally used, it has a dielectric constant of about 3 to 4, and especially polymers used in photo-alignment agents using ultraviolet light have high polarity and large dielectric constant as the photoreactor exhibits high polarity. .

Therefore, attempts have been made to manufacture low dielectric constant and low polar polymers for improving the electro-optic properties. For example, methods such as molecular design and mixing low dielectric polymers have been proposed. There is a problem that does not improve the structural limit of the polymer material causing a large dielectric constant.

For example, techniques for mixing polymers for improving the performance of optical alignment agents such as Korean Patent No. 1998-057659 are proposed, all of which focus on thermal stability of polymers, and also mix low dielectric polymers. In the case of the method, since the dielectric constant of the polymer itself is not less than 2, there is a problem that it is very limited to lower the overall dielectric constant.

Therefore, the present invention has been made to solve the above problems,

It is an object of the present invention to provide a liquid crystal aligning agent composition having a porous structure having low polarity and low dielectric constant values and thus having improved electro-optic properties.

Another object of the present invention is to provide a liquid crystal alignment film having a porous structure using the liquid crystal aligning agent composition.

Still another object of the present invention is to provide a method for producing a liquid crystal alignment film having a porous structure using the liquid crystal aligning agent composition.

Still another object of the present invention is to provide a liquid crystal device capable of realizing high quality and high quality images including the liquid crystal alignment layer.

The object of the present invention as described above is achieved by the liquid crystal aligning agent composition which consists of a polymer mixture and has a porous structure in which a porous structure is formed in a liquid crystal aligning agent composition.

And the polymer mixture, it is preferable to include a bubble forming material for providing a pore structure, wherein the bubble forming material in the group consisting of pentane-based polymer, nucleic acid-based polymer, heptane-based polymer, methanol, ethanol, acetone More preferably it is at least one or more selected.

Another object of the present invention as described above is achieved by the liquid crystal alignment film 10 having a pore structure including the liquid crystal aligning agent composition having the pore structure.

Another object of the present invention as described above is to dissolve the polymer mixture for the liquid crystal alignment in an organic solvent (S1); Mixing a bubble-forming material in the solution or mixing a mixture of a polymer mixture and a bubble-forming material in the solution (S2); Applying the solution onto the substrate (2) by spin coating or printing to form an alignment layer (S3); And (S4) aligning the liquid crystals of the alignment layer 10. The method of manufacturing the liquid crystal alignment layer 10 having the porous structure includes a.

Another object as described above is achieved by a liquid crystal device including the liquid crystal alignment layer 10 having the porous structure.

Hereinafter, a liquid crystal aligning agent composition having a porous structure according to the present invention, a liquid crystal aligning film using the same, a manufacturing method thereof, and a liquid crystal device including the liquid crystal aligning film will be described in detail.

The present invention is based on a novel technical idea of forming a porous structure in the liquid crystal aligning agent composition and thus forming a porous structure in the liquid crystal aligning film in order to achieve low polarity and dielectric constant value in the liquid crystal aligning agent.

4 is a schematic view showing a liquid crystal device including a liquid crystal aligning film 10 using a liquid crystal aligning agent composition made of a polymer mixture having a pore structure according to one embodiment of the present invention.

As shown in FIG. 4, an alignment layer 10 is formed inside the opposing substrate 20 according to the present invention, and a liquid crystal layer 40 is formed therein. The liquid crystal aligning agent composition which has the pore 50 is apply | coated.

As a preferable example of the method of forming the retained pores 50, that is, the porous structure, a pore forming material is used.

As the pore-forming substance, a substance capable of directly generating bubbles by heat or a polymer having many branches is used.

In the method using a material capable of directly forming bubbles, the bubble direct forming material is mixed with the pre-alignment polymer alignment agent of the liquid crystal alignment layer 10 and heat is applied to the polymer alignment agent while the volume expands due to vaporization of the materials. This is a method of forming the pores 50.

This method can be used when forming pores 50 having a relatively large size of several microns.

In addition, the method using a polymer having a large number of branches creates a lot of free volume in the polymer as many branches in the polymer prevent the cross packing of molecules, and thus the free volume generated as a function of pores This is how you do it.

This method can be used to form pores 50 of several nanometers in size.

The liquid crystal aligning agent composition of the present invention based on the technical idea of forming a porous structure in the liquid crystal aligning agent as described above is a preferred example of a bubble-forming material providing a porous structure in the polymer mixture, a pentane-based polymer, a nucleic acid-based polymer, Heptane-based polymer, methanol, ethanol, acetone.

The methanol, ethanol, acetone is a bubble direct forming material for directly forming a bubble, the pentane-based polymer, nucleic acid-based polymer, heptane-based polymer corresponds to a polymer having many branches, the liquid crystal aligning agent composition of the present invention Methanol, ethanol, acetone, pentane-based polymer, nucleic acid-based polymer, heptane-based polymer selected from any one or two or more.

As the pentane-based polymer, nucleic acid-based polymer, heptane-based polymer, for example, normal pentane, normal nucleic acid, normal heptane, 2-methylbutane, 2,2-methylpropane, 2-methylpentane, 3-methylpentane, 2,3 -Methylpentane, 2-methylnucleic acid, 2,2-methylpentane and the like are preferable.

As such, when bubbles are formed in the polymer mixture, an aliphatic polyolefin-based polymer including polyethylene and polypropylene-based polymers, a polystyrene-based polymer, or an acrylic polymer including polymethyl methacrylate is used. , Polyamide based polymers, polyacetal based polymers, phenolic polymers, epoxide based polymers, polyurethane based polymers, polyisocyanate based polymers, polysiloxanes Bubble formation in the case of using a polymer or using a polymer in which at least two or more of the above-described polymers are mixed (hereinafter, at least two or more selected from the above-described polymers or polymers thereof are referred to as first polymers). This is more preferable.

At this time, for the optical alignment as described below, the first polymer is a cinnamate of the following [structure 1], a chalcone of the following [structure 2], an azo compound of the following [structure 3], and a structure of the following [structure 4]. For example, the photoactive unit of any one of cinnamylidene malonate of the following [structure 5] and styryl acrylate of the following [structure 6] is included in the main chain or side chain as a photosensitive functional group.

[Structure 1]

Structure 2

Structure 3

[Structure 4]

[Structure 5]

[Structure 6]

The bubble-forming material is preferably included in 0.1 ~ 10wt% with respect to the polymer mixture.

If it is less than 0.1 wt%, there is no bubble formation effect and there is no improvement of the electro-optical properties. If it is more than 10 wt%, the ratio of bubbles is too large and there is a concern that the orientation characteristic may be lowered.

Then, in the case where the pores 50 are formed and maintained, the diameter of the pores 50 finally maintained after formation is preferably 1 to 1000 nm. If the pores 50 are less than 1 nm, the required electro-optic properties are not satisfied, and the thickness is 1000 nm. When exceeding, the diameter of the pore 50 becomes too large and there is a possibility of causing a fall of the orientation characteristic.

As described above, the method for producing a liquid crystal alignment film of the present invention based on the technical idea of forming a porous structure in a liquid crystal aligning agent is a porous structure in which the pores 50 are formed and maintained by performing alignment using the polymer mixture. It is based on the method of manufacturing the liquid crystal aligning film which has, and as a orientation method, the rubbing method and the photo-alignment method are preferable, and the method of depositing silicon oxide and the method of using an ion beam are also possible.

Hereinafter, the manufacturing method of the liquid crystal aligning film which concerns on this invention is explained in full detail.

First, for example, chlorobenzene, N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N, N-dimethylimidazolidinone (DMI), N, N-dipropylimidazolidinone (DPI), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), cyclopentanone, cyclohexanone, dichloroethane, butylcellulose, gamma butyrolactone and tetrahydrofuran (THF In the organic solvent consisting of any one or at least two or more mixed solvents selected from the group consisting of), the polymer mixture is dissolved so that the concentration of the polymer mixture with respect to the organic solvent is 1 to 20wt%, the organic solvent and the polymer Make the viscosity of the mixed solution of the mixture 1 ~ 100cps (S1).

Next, the bubble-forming substance is preferably mixed in a solution in which the polymer mixture is dissolved in an organic solvent in a predetermined amount, preferably 0.1-10 wt%, as described above.

Or mixing a bubble-forming substance in the polymer mixture with a predetermined amount, preferably 0.1-10 wt%, as described above, in a solution in which the polymer mixture is dissolved in an organic solvent. (S2).

Between the steps S1 and S2, if necessary for the removal of the impurity particles not dissolved in the organic solvent, a step of passing the solution dissolved in the organic solvent in the organic solvent to the filtration membrane may be further performed.

Next, the mixed solution is applied onto the substrate 2, for example, the ITO glass substrate 2, by a spin coating or printing method to form a alignment layer 10 (S3).

In the preparation of the liquid crystal alignment film according to the present invention, the method of forming the alignment is preferably performed by a rubbing method or an optical alignment method, and in the case of the optical alignment method, the thickness applied to the substrate is preferably 10 to 500 nm.

In the case of less than 10 nm, the alignment film is difficult to form, and in the case of more than 500 nm, the formation of the photo alignment is not easy.

In the case of the rubbing method, the thickness applied to the substrate is preferably 100 to 1000 nm.

When it is less than 100 nm, it is not suitable for rubbing, and when it exceeds 1000 nm, formation of orientation is not easy.

Next, the alignment agent is subjected to the alignment of the alignment film is formed (S4).

In the case of the photo-alignment method, the liquid crystal is formed by inclining or vertically irradiating ultraviolet rays linearly polarized using a polarizer or non-polarized ultraviolet rays not using a polarizer on the surface of the alignment film coated with the liquid crystal aligning agent having the photosensitive functional group. Orientation is performed (S4-1).

4 is a schematic view showing an irradiation step in the alignment process of the liquid crystal aligning film 10 using the photosensitive polymer liquid crystal aligning agent composition according to the present invention.

As shown in FIG. 4, the surface of the alignment layer 10 is inclined or vertically irradiated with a linearly polarized ultraviolet ray 80 using a polarizer or an unpolarized ultraviolet ray 80 without using a polarizer for 2 seconds to 10 minutes. Irradiation produces a liquid crystal aligning film 10 on the substrate 20.

The irradiation time depends on the power of the lamp. The larger the power, the shorter the irradiation time. The smaller the power, the larger the irradiation time. For lamps of approximately 500W, tilt or level for 2 seconds to 10 minutes.

Meanwhile, in the rubbing method, the liquid crystal is oriented by rubbing the surface of the alignment layer with a rubbing cloth attached to a conventional rubbing method (S4-2).

The manufacturing method of the liquid crystal element by which the orientation is formed by the liquid crystal aligning film 10 which has a porous structure which concerns on this invention is as follows.

After spraying a spacer having a predetermined size on the two photoreacted substrates 20 having the liquid crystal alignment layer 10 manufactured as described above, by attaching the adhesive between the two substrates 20 to have a constant thickness, After the curing process for 1 hour at 130 ° C to cure the adhesive to bond the two substrates 20 to prepare a device. Thereafter, the liquid crystal 40 is injected into the device, heat is applied at 100 to 130 ° C. for about 1 hour, and then a heat treatment step of dropping the temperature to room temperature is performed once.

The driving mode of the liquid crystal display according to the present invention can be applied to various modes, such as Super Twisted Nematic (STN), Twisted Nematic (TN), In Plane Switching (IPS), and Vertically Alligned Twisted Nematic (VATN) modes.

Hereinafter, the present invention will be described in more detail by explaining preferred embodiments of the present invention. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only common to those skilled in the art to complete the present disclosure. It is intended to facilitate the implementation of the invention to those with knowledge.

Example 1

Embodiment 1 relates to a liquid crystal aligning agent composition having a pore structure using a polyamide photosensitive polymer having a chalcon photosensitive functional group and a normal nucleic acid, a method of preparing a liquid crystal aligning film using the same, and a liquid crystal device including the liquid crystal aligning film.

(1) Synthesis of Chalcone Photosensitive Functional Group

10 g of 4-methoxychalcone and 2.05 g of sodium cyanide were dissolved in 100 ml of dimethyl sulfoxide and allowed to react for 24 hours. After completion of the reaction, the reaction solution was mixed with chloroform and stirred with distilled water to extract impurities. After removing the aqueous phase, chloroform was removed under reduced pressure at room temperature. The remaining solid phase was recrystallized in methanol and then dried in vacuo at 40 ° C. to obtain side chain 4-hydroxychalcone for photoreaction.

(2) Introduction of Chalcone Photosensitive Functional Groups into Triazine Rings

23.8 g of the obtained 4-hydroxychalcone was placed in a round bottom flask filled with nitrogen and dissolved in 240 ml of tetrahydrofuran from which moisture was removed. 2.4 g of sodium hydride (NaH) was added thereto and allowed to react at room temperature for 6 hours. 18.4 g of cyanuric chloride was added to a round bottom flask, and the solution was dissolved in 200 ml of tetrahydrofuran from which moisture was removed. The solution was reacted vigorously with vigorous stirring at −5 ° C. for 24 hours. After completion of the reaction, distillation under reduced pressure was carried out to remove tetrahydrofuran, and the obtained solid was dissolved in chloroform again. The solution was washed three times with distilled water in a separatory funnel to extract impurities, and then water was removed with calcium chloride. The solution was distilled under reduced pressure again to remove chloroform and recrystallized with a mixed solvent of methylene chloride and normal nucleic acid. The obtained material was filtered under reduced pressure and then vacuum dried to obtain triazine having a chalcone photosensitive functional group.

(3) Synthesis of Triazine Monomer Having Two Amine Functions

38.6 g of the triazine having the above-described chalcone photosensitive functional group was dissolved in 300 ml of distilled water in which 32.8 g of 4-aminophenol and 12 g of sodium hydroxide were dissolved in 3 g of cetyltrimethylammonium bromide, followed by a vigorous reaction for 24 hours. After completion of the reaction, the organic solution phase was separated, transferred to a separatory funnel, washed three times with distilled water to extract impurities, and then water was removed with calcium chloride. The water-removed solution was distilled under reduced pressure to remove chloroform, which is an organic solvent, and then recrystallized in a mixed solvent of methylene chloride and normal nucleic acid. The precipitated crystals were filtered under reduced pressure and dried in vacuo to obtain a triazine monomer.

(4) Polymerization of a polyamide photosensitive polymer liquid crystal aligning agent having a chalcone photosensitive functional group

53.15 g of the obtained triazine monomer was placed in a round bottom flask filled with nitrogen and dissolved in 400 ml of tetrahydrofuran from which moisture was removed. 20.24 g of triethylamine was added to this solution. After dissolving 20.3 g of terephthaloyl chloride in 100 ml of tetrahydrofuran from which water was removed, the mixture was stirred vigorously while slowly dropping into the solution in which the triazine monomer and triethylamine were dissolved, followed by reaction for 12 hours. After completion of the reaction, the reaction solution was slowly poured into methanol to precipitate and filtered, and the precipitate was dried in vacuo. The obtained precipitate was again dissolved in tetrahydrofuran and then precipitated in methanol twice. After vacuum drying, a polyamide photosensitive polymer liquid crystal aligning agent having a chalcon photosensitive functional group was finally polymerized using a triazine ring.

(5) Preparation of liquid crystal display element

The obtained polyamide photosensitive polymer (C1) liquid crystal aligning agent was dissolved in 5 wt% of a solvent (NMP) to form a solution. The sample was passed through a solution to a filtration membrane having a micropore size of 0.1 탆 to remove undissolved impurity particles. Meanwhile, 0.1 to 10 wt% of normal nucleic acid is mixed with the polyamide photosensitive polymer (C1), and the solid stored at 10 atm for 1 hour is mixed and dissolved in the prepared alignment agent solution. The solution is printed on a glass substrate coated with a transparent electrode to a thickness of 10 to 500 nm to apply a photoalignment agent. The substrate was left at about 80 ° C. for 1 hour to form bubbles in the alignment film, and the glass substrate was then heat treated at 180 ° C. for about 1 hour to remove the solvent. The glass substrates were prepared by inducing a complex photoreaction such as photopolymerization of chalcone groups and photolysis of polymer chains through a single irradiation of light for 2 seconds to 10 minutes at an angle of 20 ° to ultraviolet light of a 500W mercury lamp. It was.

Subsequently, a spacer having a size of 4˜5 μm was sprinkled on the photoreacted two glass substrates, and then attached using a epoxy adhesive such that the cell gap between the two glass substrates was 4˜5 μm. The cell was subjected to a curing process at 130 ° C. for 1 hour to cure the epoxy adhesive so that the two glass substrates were completely bonded to complete the manufacture of the cell.

After injecting the liquid crystal into the finished cell at room temperature, the crystals were treated at a clearing temperature, that is, at 100 to 130 ° C. for 5 minutes, to evenly orient and cool to complete the device.

Example 2

Embodiment 2 relates to a liquid crystal aligning agent composition having a porous structure using a polyacrylic polymer having a cinnamate photosensitive functional group and ethanol, a liquid crystal aligning film production method using the same, and a liquid crystal device including the liquid crystal aligning film.

(1) Introduction of cinnamate functional group

14.8 g of cinnamic acid was placed in a round bottom flask filled with nitrogen, and 17.8 g of thionyl chloride (SOCl ₂ ) was added thereto, followed by stirring. Then, 0.5 ml of dimethylformamide (DMF) was further added to the flask, followed by reaction at room temperature for 24 hours. After the reaction was completed, distillation under reduced pressure was carried out to obtain 16 g of cinnamoyl chloride.

(2) formation of amide linkages

7 g of aminophenol was placed in a round bottom flask filled with nitrogen, and 16 g of cinnamoyl chloride diluted in 10 ml of methylene chloride (MC) was slowly added dropwise while keeping 50 ml of pyridine at 0 ° C. After stirring for 1 hour, the reaction product formed a precipitate in 3N aqueous hydrochloric acid solution. The precipitate was filtered, the water was completely removed, recrystallized from methanol, and filtered under reduced pressure. The obtained solid substance was decompressed in vacuum to obtain 18 g of 4-hydroxyphenylcinamide.

(3) an acrylic monomer having a cinnamate photosensitive functional group

15 g of the 4-hydroxyphenyl cinnamid obtained was placed in a round bottom flask filled with nitrogen, 80 ml of tetrahydrofuran (THF) and 30 ml of triethylamine (TEA) were added thereto, dissolved at 0 ° C., and 7 g of methacryloyl chloride. Was slowly added dropwise. After the dropping was completed, the reaction was carried out for 1 hour, and the reactant was formed into a precipitate in 3N aqueous hydrochloric acid solution. . The obtained solid substance was decompressed in vacuum to obtain 10 g of an acrylic monomer having a cinnamate photosensitive functional group.

(4) Polymerization of Acrylic Photoalignment Agent

After dissolving 10 g of the obtained acrylic monomer in 100 ml of tetrahydrofuran, the temperature was maintained at 80 ° C., and then 0.1 g of 2,2 ^and -azobisisobutyronitrile as a radical initiator was slowly added dropwise. After reacting for 12 hours, the reactant formed a precipitate in methanol, and the precipitate was filtered under reduced pressure and dried in vacuo. After dissolving the obtained polymer in tetrahydrofuran and precipitating in methanol twice, vacuum drying was performed to obtain an acrylic polymer liquid crystal aligning agent having low polarity and high light efficiency.

(5) Preparation of liquid crystal display element

The obtained acrylic photosensitive polymer (A1) liquid crystal aligning agent was dissolved in 5 wt% of a solvent (NMP) to form a solution. The sample was passed through a solution to a filtration membrane having a micropore size of 0.1 탆 to remove undissolved impurity particles. On the other hand, 0.1 to 10 wt% of ethanol is mixed with the acrylic photosensitive polymer (A1), and the solid stored for 1 hour at 10 atm is mixed and dissolved in the prepared alignment agent solution. The solution is printed on a glass substrate coated with a transparent electrode to a thickness of 10 to 500 nm to apply a photoalignment agent. The substrate was left at about 80 ° C. for 1 hour to form bubbles in the alignment film, and the glass substrate was then heat treated at 180 ° C. for about 1 hour to remove the solvent. These glass substrates were subjected to complex photoreaction such as photopolymerization of cinnamate group and photodegradation of polymer chain through one-time irradiation of light for 2 seconds to 10 minutes at an angle of 20 ° to ultraviolet light of 500W mercury lamp. Prepared.

Subsequently, a spacer having a size of 4˜5 μm was sprinkled on the photoreacted two glass substrates, and then attached using a epoxy adhesive such that the cell gap between the two glass substrates was 4˜5 μm. The cell was subjected to a curing process at 130 ° C. for 1 hour to cure the epoxy adhesive so that the two glass substrates were completely bonded to complete the manufacture of the cell.

After injecting the liquid crystal into the finished cell at room temperature, the crystals were treated at a clearing temperature, that is, at 100 to 130 ° C. for 5 minutes, to evenly orient and cool to complete the device.

Comparative Example 1

In Comparative Example 1, a device was fabricated by coating a glass substrate (5 wt% in NMP) in which polyvinylcinnamate, which is a polyvinyl-based polyvinyl-containing functional group, was dissolved.

Comparative Example 2

In Comparative Example 2, a liquid crystal device was fabricated by forming pores in an alignment layer by using a solution of polyvinylcinnamate, which is a polyvinyl-based polyvinylcinnamate having a cinnamate photosensitive functional group (5 wt% in NMP), and using a normal nucleic acid as in Example 1. .

The residual DC and VHR were measured as follows to evaluate the electro-optic properties of Example 1 and Example 2, and to compare the electro-optical properties of Comparative Example 1 and Comparative Example 2.

First, the measurement of the residual DC was applied while varying the DC voltage at both ends of the liquid crystal device between -10V ~ 10V to measure the capacitance value at this time and to obtain the residual DC from the magnitude of the hysteresis value.

The liquid crystal elements used were samples of TN structure having a thickness of 4 to 6 μm, which were prepared by the above production method. The two electrodes of the prepared liquid crystal device were connected to the LCR meter, and the change of capacitance was recorded at 1 kHz while the DC power was changed from 0V to 10V, 0V, -10V. The residual DC was measured by obtaining a history of capacitance change with respect to voltage.

In addition, the VHR was measured by applying a pulse having a width of 64 Hz at a period of ± 1 V and 60 Hz to measure the rate at which the initially applied voltage was maintained within one period.

Table 1 shows the residual DC, VHR values according to the nucleic acid mixing ratio in Example 1.

C1: N-Hexane weight ratio 1: 0 (C1 only) 99: 1 90:10 R-DC 20 ℃ 37mV 25 mV 19 mV 60 ℃ 75 mV 49 mV 43mV VHR 20 ℃ 94% 98% 98% 60 ℃ 90% 94% 95%

As can be seen in Table 1, according to the mixing ratio of the polyamide photosensitive polymer and nucleic acid in Example 1, the residual DC of 19 ~ 37mV at 20 ℃ was measured and VHR was 94 ~ 98%, 60 ℃ The residual DC at 43-75mV was measured and the VHR was 90-95%. Therefore, the lower the ratio of nucleic acid, the higher the residual DC value and the lower the VHR ratio, the lower the optical properties.

Table 2 shows the residual DC, VHR values according to the ethanol mixing ratio in Example 2.

A1: Ethanol weight ratio 1: 0 (A1 only) 99: 1 90:10 R-DC 20 ℃ 40 mV 27 mV 21 mV 60 ℃ 63mV 54 mV 35 mV VHR 20 ℃ 95% 97% 97% 60 ℃ 91% 93% 95%

As can be seen in Table 2, according to the mixing ratio of the acrylic photosensitive polymer and ethanol in Example 2, the residual DC of 21 ~ 40mV was measured at 20 ℃ and VHR was found to be 95 ~ 97%, at 60 ℃ Residual DCs of 35-63mV were measured and VHR was 91-95%. Therefore, the lower the ratio of ethanol, the higher the residual DC value and the lower the VHR ratio, the lower the electro-optic properties.

Table 3 shows the results of measuring the residual DC and VHR values in Comparative Example 1 and Comparative Example 2, respectively.

Comparative Example 1 Comparative Example 2 R-DC 20 ℃ 89 mV 42 mV 60 ℃ 117 mV 64 mV VHR 20 ℃ 89% 93% 60 ℃ 82% 89%

As can be seen in Table 3, in each case of 20 ° C and 60 ° C, Comparative Example 1 without pores was measured to have a higher residual DC and lower VHR than Comparative Example 2 with pores. Therefore, in the case of Comparative Example 2 including pores, it was found that the electro-optic properties were improved.

In conclusion, when the pores were formed by using a pore-forming material such as nucleic acid or ethanol, the electro-optic properties could be improved compared to the case where no pores were formed.

The present invention improves the electro-optical properties such as residual DC and VHR by improving problems such as high polarity and large dielectric constant of the conventional alignment agent, and also reduces voltage drop occurring along the signal line in the display, resulting in afterimage and flicker. It solves the phenomenon, makes it possible to apply to large-area display production, and achieves the effect of realizing high quality display quality.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

1 is a schematic view showing an alignment process of a liquid crystal alignment film by a conventional rubbing method,

2 is a schematic view showing the structure of a conventional liquid crystal element;

3 is a circuit diagram showing a capacitance of the liquid crystal element of FIG. 2;

4 is a schematic view showing a liquid crystal device including a liquid crystal aligning film using a liquid crystal aligning agent composition composed of a polymer mixture having a pore structure according to one embodiment of the present invention;

5 is a schematic view showing an irradiation step of an alignment process of a liquid crystal alignment layer using the photosensitive polymer liquid crystal aligning agent composition according to an embodiment of the present invention.

* A brief description of the major reference marks *

10: photo-alignment film 20: substrate

30: transparent electrode ITO 40: liquid crystal layer

50: pore 80: ultraviolet rays

Claims (21)

Liquid crystal aligning agent composition WHEREIN: As a liquid crystal aligning agent composition which consists of a polymer mixture, and a porous structure is formed, The polymer mixture is an aliphatic polyolefin-based polymer including polyethylene, polypropylene series; Polystyrene-based polymers; Acrylic polymers including polymethyl methacrylate; Polyamide-based polymers; Polyacetal polymer; Phenolic polymers; Epoxide-based polymers; Polyurethane-based polymers; Polyisocyanurate polymers; And at least one first polymer selected from the group consisting of polysiloxane-based polymers, The first polymer is a cinnamate of the following [Structure 1]; The chalcone of the following [Structure 2]; Azo compounds of the following [Structure 3]; The imide of the following [Structure 4]; Cinnamylidene malonate of the following [Structure 5]; And any photoactive unit selected from the group consisting of styryl acrylate of the following [Structure 6] in the main chain or in the side chain. [Structure 1] Structure 2 Structure 3 [Structure 4] [Structure 5] [Structure 6] The method of claim 1, The polymer mixture comprises a bubble-forming material for providing a porous structure, The bubble-forming material is composed of at least one selected from the group consisting of pentane-based polymer, nucleic acid-based polymer, heptane-based polymer, methanol, ethanol, acetone, characterized in that it comprises 0.1 to 10wt% based on the polymer mixture Liquid crystal aligning agent composition which has a porous structure. delete delete delete delete The method of claim 1, The porous structure is a liquid crystal aligning agent composition having a porous structure, characterized in that the diameter of the pores 50 is 1 ~ 1000nm. The liquid crystal aligning film which has the porous structure characterized by including the liquid crystal aligning agent composition of any one of Claims 1, 2, and 7. Dissolving the polymer mixture for liquid crystal alignment in an organic solvent (S1); Mixing a bubble-forming material into the solution or mixing a mixture of a polymer mixed liquid crystal aligning agent and a bubble-forming material into the solution (S2); Applying the solution onto the substrate (20) to form an alignment layer (S3); And As a method of manufacturing a liquid crystal alignment film comprising the step (S4) of orienting the liquid crystal of the alignment film 10, The polymer mixture is an aliphatic polyolefin-based polymer including polyethylene, polypropylene series; Polystyrene-based polymers; Acrylic polymers including polymethyl methacrylate; Polyamide-based polymers; Polyacetal polymer; Phenolic polymers; Epoxide-based polymers; Polyurethane-based polymers; Polyisocyanurate polymers; And at least one first polymer selected from the group consisting of polysiloxane-based polymers, The first polymer is a cinnamate of the following [Structure 1]; The chalcone of the following [Structure 2]; Azo compounds of the following [Structure 3]; The imide of the following [Structure 4]; Cinnamylidene malonate of the following [Structure 5]; And any photoactive unit selected from the group consisting of styryl acrylate of the following [Structure 6] in the main chain or in the side chain. [Structure 1] Structure 2 Structure 3 [Structure 4] [Structure 5] [Structure 6] The method of claim 9, wherein the step S1, A method of producing a liquid crystal alignment film having a porous structure, characterized in that the polymer mixture is dissolved at a concentration of 1 to 20 wt% with respect to the organic solvent, and the viscosity of the mixed solution of the polymer mixture and the organic solvent is 1 to 100 cps. The method of claim 9, wherein the step S1, As the organic solvent, chlorobenzene, N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N, N-dimethylimidazolidinone (DMI), N, N-dipropylimidazolidinone (DPI), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), cyclopentanone, cyclohexanone, dichloroethane, butylcellulose, gamma butyrolactone and tetrahydrofuran (THF Method for producing a liquid crystal aligning film, using any one or at least any two or more mixed solvents selected from the group consisting of delete delete The method of claim 9, wherein the step S2, A method for producing a liquid crystal alignment film having a porous structure, characterized by using at least one selected from the group consisting of a pentane-based polymer, a nucleic acid-based polymer, a heptane-based polymer, methanol, ethanol and acetone as the bubble-forming substance. The method of claim 14, wherein the step S2, A method for producing a liquid crystal alignment film having a porous structure, characterized in that the bubble-forming material is contained 0.1 to 10wt% based on the polymer mixture. The method of claim 14, wherein the step S2, A method for producing a liquid crystal alignment film having a porous structure, characterized in that the diameter of the pores 50 formed by the bubble-forming substance is 1 to 1000 nm. The method of claim 9, wherein the step S4, A method for producing a liquid crystal alignment film having a porous structure, characterized in that the liquid crystal is oriented by inclining or vertically irradiating ultraviolet (80) linearly polarized using a polarizer or non-polarized ultraviolet (80) without using a polarizer. The method of claim 17, wherein the step S3, The thickness of the orientation film 10 apply | coated on the board | substrate 20 is 10-500 nm, The manufacturing method of the liquid crystal aligning film which has a porous structure characterized by the above-mentioned. The method of claim 9, wherein the step S4, The manufacturing method of the liquid crystal aligning film which has a porous structure characterized by rubbing the surface of the oriented film (10) and orientating a liquid crystal. The method of claim 19, wherein the step S3, The thickness of the orientation film 10 apply | coated on the board | substrate 20 is 100-1000 nm, The manufacturing method of the liquid crystal aligning film which has a porous structure characterized by the above-mentioned. A liquid crystal element comprising a liquid crystal aligning film (10) produced by the method of any one of claims 9-11 and 14-20.