KR101333592B1 - Method of forming alignment layer of liquid crystal display device - Google Patents

Abstract

The present invention relates to a method for forming an alignment film of a liquid crystal display device, wherein the method for forming an alignment film according to the present invention comprises a photoalignment material for an alignment film made of at least one monomer selected from the group consisting of monomers represented by the following general formula (1) on a substrate: Applying the light, irradiating light to the photo-alignment material formed on the substrate, applying heat to the photo-alignment material formed on the substrate, and post-heating the post-heat treatment to the light-aligning material to which the light is irradiated. Characterized in that it comprises a step of forming.

In the formula, R is represented by the following formula (2).

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UV alignment, cyclobutane anhydride, process conditions

Description

Method for forming alignment layer of liquid crystal display device {METHOD OF FORMING ALIGNMENT LAYER OF LIQUID CRYSTAL DISPLAY DEVICE}

1 is a schematic cross-sectional view of a liquid crystal display device according to the prior art;

Figure 2 is a graph showing the infrared absorbance of each when irradiated with ultraviolet light in the oxygen and nitrogen environment to the polymer consisting of CBDA monomer.

3 is a graph showing the delay value of the alignment layer according to the irradiation energy of ultraviolet rays.

Figure 4 is a graph showing the glass transition temperature (Tg) of the before / after alignment film of the post-heat treatment process of CBDA.

5 is a comparative example graph showing a difference in luminance of cells under predetermined conditions;

6 is a comparative example and an example graph showing a difference in luminance of cells under predetermined conditions;

The present invention relates to an optical alignment material for an alignment film of a liquid crystal display device and a method for forming an alignment film using the same, and more particularly, to an alignment film optical alignment that can align the liquid crystal of the liquid crystal display device uniformly by aligning the alignment film using ultraviolet rays. It relates to ash and a method of forming an alignment film using the same.

Recently, with the development of the information society, as the demand for various display devices increases, research on flat panel display devices such as liquid crystal display (LCD) and plasma display panel (PDP) has been actively conducted. . Among such display devices, liquid crystal displays (LCDs) are in the spotlight due to mass production technology, ease of driving means, and high quality.

1 is a cross-sectional view schematically showing a cross section of a liquid crystal display device 1 according to the prior art.

As shown in the figure, the liquid crystal display device 1 includes a second substrate 3 facing the first substrate 5 and the first substrate 5, and the first substrate 5 and the second substrate 3. It consists of the liquid crystal layer 7 formed in between.

The liquid crystal forming the liquid crystal layer 7 is a material having optical anisotropy, and thus the light transmittance may be adjusted because the orientation varies depending on the applied voltage. Accordingly, a still image or a moving image corresponding to the light transmittance of the liquid crystal layer is represented on the liquid crystal display device 1.

The first substrate 5 is a substrate on which a thin film transistor (TFT), which is a driving element, is formed. Although not shown in the drawing, a plurality of pixels are formed, and each pixel is formed of a thin film transistor.

The second substrate 3 is a color filter substrate, and a color filter layer for realizing color is formed. In addition, a pixel electrode and a common electrode are formed on the first substrate 5 and the second substrate 3, and an alignment layer 10 for aligning liquid crystal molecules of the liquid crystal layer 7 is coated.

The first substrate 5 and the second substrate 3 are bonded by a sealing material 9. The liquid crystal layer 7 formed between the first substrate and the second substrate is driven by a thin film transistor (not shown) formed on the first substrate 5.

In order to manufacture the liquid crystal display device 1 as described above, the alignment layer 10 for aligning the liquid crystal molecules of the liquid crystal layer 7 on the surface where the first substrate 5 and the second substrate 3 face each other. Go through the process of forming. The alignment layer 10 is formed to determine the initial alignment state of the liquid crystal layer 7, and is formed to have a different degree of line tilt angle (pretilt angle) according to the method of the liquid crystal display device.

The method mainly used for forming the pretilt angle on the alignment film is rubbing. Rubbing is a method of orientation by rubbing in a fixed direction using a roller wrapped around the velvet or the surface after applying the alignment film on the substrate.

However, since the rubbing method is performed through the direct physical contact between the alignment layer and the roller, it causes a device defect due to dust generation or static electricity generation. In addition, when applying a large area, not only uniformity may appear, but there is a problem that a cleaning / drying process for removing contamination such as dust even after rubbing is additionally required.

In order to solve the above problems, various alignment methods have been proposed. For example, a method using a Langmuir-Blodgett film, a method using UV irradiation, a method using lateral deposition of silicon dioxide, a method using a micro-groove formed by photolithography, And a method using ion beam irradiation.

Among them, an alignment method using ultraviolet rays (UV) is a method of determining the alignment direction of a polymer by irradiating polarized ultraviolet rays to the polymer film forming the alignment film by cutting, generating, or changing a bond of the polymer film in a predetermined direction.

However, when AC voltage is continuously applied while driving the liquid crystal layer after the ultraviolet alignment, AC afterimage may appear in some areas, thereby causing a problem in that luminance of the area is increased. These AC afterimages are often restored over a long time even if they remain permanent or restored.

The AC residual image appears to be changed by the alignment axis being stressed by the voltage applied to drive the liquid crystal layer. The change of the alignment axis can be made in two ways. The first is a case where the direction of the overall director is partially distorted, and the second is a case where the uniformity of each director is inferior even though the overall sum of the orientation directors is the same. In the first case, the director itself is distorted, so the pretilt angle of the liquid crystal molecules may be changed to cause light leakage. In the second case, the overall pretilt angle of the liquid crystal molecules may be maintained, but the disorder of each pretilted liquid crystal may be reduced. Increased light leakage may appear.

In any of the above two cases, since the orientation force is lowered, an afterimage may appear or the brightness may increase.

The present invention has been made to solve the conventional problems as described above, an object of the present invention is to provide a method for forming a high-quality alignment film by reducing the afterimage AC by selecting the process conditions according to the characteristics of the material have.

Method for forming an alignment film according to the present invention for achieving the above object, the step of applying a photo-alignment material for an alignment film made of at least one monomer selected from the group consisting of monomers represented by the formula (1) on the substrate, on the substrate Irradiating light to the photo-alignment material formed on the substrate; applying heat to the photo-alignment material formed on the substrate; and post-heating the post-heating treatment on the light-aligning material. It features.

[Formula 1]

In the formula, R is represented by the following formula (2).

(2)

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The alignment method using ultraviolet rays among the methods for orienting the alignment layer of the liquid crystal display device is a method of determining the alignment direction of the polymer by cutting off part of the bond of the polymer layer forming the alignment layer by irradiating with polarized ultraviolet rays.

In the alignment method using ultraviolet rays, photo isomerization which largely changes to cis and trans isomers and determines the orientation direction, and 2,2 monomers are combined into dimers Photo dimerization to determine the crystallization, photo decomposition to determine the orientation direction by decomposing molecules with constant bonds, and photo rearrangement to determine the orientation direction by changing the arrangement positions of molecules For example.

In both cases, the alignment material forming the alignment layer is irradiated with ultraviolet rays polarized in a specific direction to apply energy, thereby causing a chemical reaction related to bonding in a predetermined direction. In particular, by irradiating polarized ultraviolet rays, the molecular bonds are chemically reacted with the alignment material by cleaving, isomerizing, dimerizing or rearranging the molecules, thereby making the alignment material anisotropic.

However, when the AC voltage is continuously applied while driving the liquid crystal layer after the ultraviolet alignment, AC afterimage may appear in some areas, thereby causing a problem in that the luminance of the area is increased.

The increase in luminance due to the afterimage of AC may be judged as a case in which the entire alignment axis is distorted under AC stress and the alignment axis is maintained but the orientation force is decreased due to uniformity. Both of the above phenomena form an alignment layer. Due to the flowability of the material, in order to control the flowability of the material of the alignment material, an alignment material having a high glass transition temperature (Tg) is required.

The present invention is optimized in the manufacture of a liquid crystal display device comprising an alignment material having a low fluidity and high heat resistance (that is, a high glass transition temperature) and an optical alignment material in the UV alignment using photodimerization. It is related to process conditions.

Hereinafter, the present invention will be described with reference to the drawings.

Representative alignment materials for ultraviolet alignment are polyimide materials using cyclobutane anhydride (CBDA, cyclobutane dianhydride). Formula 1 shows a CBDA monomer, and a polyimide photoalignment material using CBDA is a material for inducing anisotropy by photolysis reaction of CBDA to orient liquid crystal molecules.

[Formula 1]

In this case, R may come in various functional groups. One example is the case where R is oxydianiline (ODA, oxydianiline), CBDA-ODA is a representative ultraviolet alignment material of the CBDA-based alignment material (JJAP. Vol. 38, L1435 (1999); Vol. 42, L67 (2003)) CBDA-ODA is shown in Formula 3.

(3)

When the CBDA-based polyimide is irradiated with UV light, CBDA is decomposed by a photolysis reaction, and as shown in Scheme 1, the decomposition product produces maleimide and photoacidification byproducts.

The characteristics of the CBDA-based material as described above has the disadvantage that the molecular weight decreases when irradiated with ultraviolet light, that is, the thermal properties of the material, that is, the heat resistance decreases.

Most photo-alignment materials, such as the above-mentioned CBDA-ODA is adopted in the main chain of a relatively flexible structure, in order to increase the reactivity of the photoreactor to ultraviolet light so that the dimerization reaction of the photoreactive group can easily occur. However, the flexibility of the main chain is such that the liquid crystal alignment is influenced by an externally acting thermal or electrical stimulus, in particular, AC, resulting in an afterimage and it is difficult to achieve stable alignment. For example, the CBDA-ODA described above has a low heat resistance of the material due to the flexible nature of the ether linkage and its structure can be changed relatively easily, resulting in permanent AC afterimage.

The present invention is a polyimide photo-alignment material using CBDA, comprising a monomer formed in a rod-like structure to improve the straightness of the alignment material in order to improve the heat resistance at the time of photo-alignment as described above It is characterized by.

In view of the above-mentioned CBDA in terms of heat resistance, since the CBDA is already fixed, the heat resistance of the material is determined by the structure of R, which is a functional group. R is selected from the group consisting of functional groups represented by the following formula (2).

(2)

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In this case, the structure of the substituent R is a structure for improving the heat resistance of the material, and the substituent for improving the heat resistance of the material is not limited thereto, and a single structure or a form of a copolymer of the selected structure may be possible.

In addition, in the polymer alignment layer including the monomer, when the alignment layer is made of only the monomer, the viscosity of the material may increase, and in this case, in order to lower the viscosity of the alignment layer material, the structure of some flexible form, that is, aliphatic Or an aromatic chain or a functional group such as an ether, an ester or a carbonyl group such as ODA, may further include a structure in which two or more aliphatic or aromatic groups are connected to each other.

Polymers composed of monomers having functional groups as described above have reduced fluidity of the material and improved heat resistance, so that the arrangement does not easily change and AC afterimage is reduced.

And this invention includes the method of forming an oriented film using said photo-alignment material.

Method for forming an alignment film according to an embodiment of the present invention in a liquid crystal display device, the step of applying a photo-alignment material for an alignment film made of at least one monomer selected from the group consisting of monomers represented by the formula (1) on a substrate, the Firing by applying heat to the photo-alignment material formed on the substrate, heating the photo-alignment material formed on the substrate, irradiating light to the photo-alignment material and post-heat treatment to the photo-alignment material irradiated with the light ( post-baking) to form an alignment layer.

Referring to the alignment film forming method according to the invention in order as follows.

In order to form an alignment layer, first, an optical alignment material comprising at least one monomer selected from the group consisting of monomers represented by Chemical Formula 1 is coated on a substrate to form an optical alignment material on the substrate. The method of coating the photo-alignment material on the substrate is not particularly limited, and methods such as roll printing or slit coating are also irrelevant. In addition to the method of applying the photo-alignment material, if the photo-alignment material can be formed on the substrate is not limited to the above method.

Then, light is irradiated to the optical alignment material formed on the substrate.

In this case, the irradiated light is characterized in that the polarized ultraviolet light. Although it may be irradiated with light of an appropriate wavelength if necessary, ultraviolet light is preferable because it can supply the appropriate energy for the reaction related to the photolysis of the polymer consisting of the monomer consisting of the above formula. And it is preferable to irradiate the polarized ultraviolet rays to induce bonding or cleavage to have a constant direction. Hereinafter, the use of polarized ultraviolet rays will be described as a preferred embodiment.

Here, the step of irradiating the ultraviolet light to the optical alignment material formed on the substrate is preferably carried out in a nitrogen environment. Figure 2 is a graph showing the infrared absorbance (absorbance) as a and b, respectively, when ultraviolet rays are irradiated to the polymer consisting of CBDA monomers in an oxygen environment and a nitrogen environment, respectively.

As shown in FIG. 2, in particular, the absorbance of carbonyl (-CO-, carbonyl) groups, the carbonyl group usually absorbs light of 1820 ~ 1660 cm ^-1 , the absorbance of the irradiated sample in the nitrogen environment The width of the peak of the absorbance (b) of the irradiated sample in the oxygen environment is wider than that in (a). This seems to increase the absorbance due to the easy photooxidation reaction when irradiated with ultraviolet light in the oxygen environment. Therefore, in order to minimize such side reactions, it is desirable to irradiate ultraviolet rays in a nitrogen environment.

And, wherein the irradiation energy of ultraviolet ray to be irradiated to the photo-alignment material is characterized in that the 0.05J / cm ² to 3.0J / cm ² with a wavelength of 254nm, characterized in that preferably the 1.0J / cm ² .

3 illustrates a phase difference retardation value of an alignment layer according to irradiation energy of ultraviolet rays. In this figure, the phase difference delay value according to the temperature at the time of ultraviolet irradiation, the phase difference delay value before post-heat treatment, and the phase difference delay value after post-heat treatment are shown, respectively.

The retardation delay value refers to a retardation value according to the difference in the phase of light passing through the long axis and the short axis in the polymer forming the alignment layer. The retardation value also increases as the anisotropy of the alignment layer increases.

As shown, the retardation delay value of the alignment layer unit film changes according to the irradiation amount of ultraviolet rays. Up to about 1 J / cm ² , the larger the dose, the larger the phase retardation value. When the value is irradiated, the retardation delay value does not increase and decreases.

In particular, in the case of a dose of 1.0J / cm ² or less in the irregular order, as the case may be irradiated at a high temperature and then investigated in more, but have a high phase difference retardation value, regardless of whether the heat treatment is greater than 1.0J / cm ^2, the value after the heat treatment whether or not It has a phase difference delay value, and at 1.0 J / cm ² or more, the phase difference delay value becomes smaller after the post-heat treatment.

These results indicate that the phase retardation value increases the fluidity when irradiated with ultraviolet rays of 1.0 J / cm ² or more. When irradiated with ultraviolet rays above a predetermined level, photolysis occurs excessively or side reactions occur due to sufficient energy supply. Is caused. In other words, when photolysis or side reactions occur more than necessary, the number of portions where the bonds of the polymer molecules are cleaved increases, which increases the fluidity of the alignment layer.

Therefore, when irradiating ultraviolet rays of 1.0 J / cm ² or more, the fluidity due to photolysis of the alignment layer is increased, so the irradiation energy of ultraviolet rays is preferably 1.0 J / cm ² or less. However, depending on the low black brightness or the like, more irradiation energy may be required. However, in order to form an alignment layer with ultraviolet rays, a minimum amount of irradiation must be satisfied and at least 0.05J / cm ² is irradiated. All of the irradiation dose is based on the case of ultraviolet rays of 254nm wavelength, when the irradiation with a different wavelength is characterized in that the irradiation with the corresponding energy.

An embodiment of the present invention includes applying heat to an optical alignment material formed on the substrate. Applying the heat corresponds to removing the maleimide formed by photolysis.

At this time, the step of applying heat to the photo-alignment material and the step of irradiating ultraviolet light is characterized in that it is made at the same time. That is, the ultraviolet ray may be irradiated after the heat is applied to the optical alignment material formed on the substrate, but it is preferable to irradiate the ultraviolet ray at the same time as the heat is applied.

The reason for irradiating UV light while heating the photo-alignment material is as follows.

When CBDA-based polyimide is irradiated with ultraviolet rays as shown in Scheme 1, CBDA is decomposed by a photolysis reaction to produce maleimide and photoacidification byproducts as the decomposition products.

[Reaction Scheme 1]

The maleimide produced when CBDA is photolyzed by ultraviolet light is randomly placed without orientation but does not actually affect orientation. However, there is a problem in that the heat resistance of the alignment layer is weakened by breaking the bond of the polymer.

Therefore, in order to improve the heat resistance of the material, it is necessary to induce crosslinking reaction of maleimide to form a three-dimensional network bond.

Crosslinking reaction of maleimide can be achieved by irradiating an ultraviolet-ray or applying heat. In the case of irradiating ultraviolet rays for the crosslinking reaction, since the photolysis reaction as well as the reverse reaction proceed simultaneously, the maleimide generated by the photolysis reaction must be removed through another reaction for larger anisotropy formation.

To this end, the embodiment of the present invention is characterized in that the thermal crosslinking reaction is induced by heat treatment to the alignment material produced maleimide. The thermal crosslinking reaction has different driving forces as compared to the photocrosslinking reaction, and thus proceeds to another reactor, and finally forms a three-dimensional network bond between the maleimide and the polymer.

At this time, in order to remove the maleimide at the same time irradiated with ultraviolet rays, the photocrosslinking reaction may be performed simultaneously with the thermal crosslinking reaction.

As described above, heat resistance of the alignment layer is enhanced by inducing a thermal crosslinking reaction of the maleimide formed by the photolysis reaction. In addition, when irradiated with ultraviolet rays while applying heat, the temperature of the substrate can be increased by low irradiation energy, and the photolysis reaction can easily occur due to the provision of energy.

The step of applying heat to the photo-alignment material formed on the substrate may vary depending on the amount of UV radiation or the monomer constituting the photo-alignment material is preferably characterized in that the heat of about 18 ℃ ~ 240 ℃. 3 corresponds to an embodiment in which 170 ° C, 200 ° C, and 230 ° C are taken as an example.

After irradiating ultraviolet light under the above irradiation conditions, the alignment material is subjected to post-heating to form an alignment layer.

After heat treatment, the remaining maleimide after heat treatment and UV irradiation is stabilized by combining with polymer and stabilizing energy state by applying energy to other unstable molecular bonds to reduce fluidity and increase heat resistance.

After the heat treatment is performed for about 1 hour at a temperature of about 200 ℃.

Figure 4 shows the glass transition temperature (Tg) of the before / after alignment film of the post-heat treatment process of CBDA. CBDA exhibits a glass transition temperature of about 280 ° C. before irradiating ultraviolet rays, but the glass transition temperature gradually decreases due to the increase of fluidity as the ultraviolet rays are irradiated. However, after the heat treatment process, the bond between the maleimide and the polymer is reduced, the fluidity is decreased, and the heat resistance is increased, so that the glass transition temperature is higher than 300 ° C.

As described above, when the alignment layer is formed according to the exemplary embodiment of the present invention, the heat resistance of the alignment layer increases and the fluidity decreases. The decrease in the fluidity of the alignment layer reduces the phenomenon that an afterimage occurs due to the liquid crystal alignment being influenced by an externally acting heat or an electrical stimulus, in particular, AC.

5 and 6 are graphs for indicating whether or not afterimage AC.

5 shows a liquid crystal cell divided into an applying part and an unapplying part at an external temperature of 60 ° C. to form a mosaic pattern. After applying 14 Vpp of AC to the cell for 24 hours, the power is turned off, and again 2 Vpp of AC is applied at a time of 0.5 hour. The difference between the applied portions and the unapplied portions is shown.

At this time, Comparative Example 1 of Figure 5 is the difference in luminance when the alignment film is formed by using rubbing, Comparative Examples 2 to 4 is a heat treatment after UV treatment using a conventional alignment film (R = cinnamate, chalcone, cumarine) This is a luminance difference when the alignment film is formed by conventional ultraviolet irradiation without heat treatment. In this case, the ultraviolet irradiation doses of Comparative Examples 2 to 4 are 0.8J / cm ² , 1.0J / cm ² , 1.2J / cm ² , and 1.5J / cm ² , respectively, and represent minimum values of the luminance difference according to R. (Hereinafter, the unit of luminance difference is cd / m ^2. )

As shown, in the case of the conventional invention, the luminance difference when the alignment film is formed by rubbing is 0.5 or less, but in the case of the alignment films according to Comparative Examples 2 to 4, the luminance difference is at least 2, which is higher than that due to rubbing. You can see that the difference is much larger. The large difference in luminance can be interpreted to mean that an afterimage due to AC remains without the liquid crystal returning to its original state.

On the other hand, Comparative Example 1 of FIG. 6 is the same as Comparative Example 1 of FIG. 5, and is a luminance difference when the alignment layer is formed by using the rubbing of the conventional invention, and Examples 1 to 4 show the luminance of the alignment layer formed according to the present invention. The difference is shown.

In Examples 1 to 4, the liquid crystal cell was divided into an applied part and an unapplied part at an external temperature of 60 ° C. to form a mosaic pattern. After applying 14 Vpp of AC to the cell for 24 hours, the power was turned off. AC is applied to show the difference in luminance between the applying portion and the unapplying portion. In this case, UV irradiation doses of Examples 2 to 4 are 0.8J / cm ² , 1.0J / cm ² , 1.2J / cm ² and 1.5J / cm ² , respectively, wherein R of CBDA used corresponds to a phenyl group.

As shown, according to Examples 1 to 4 of the present invention, it can be seen that the luminance difference is almost no difference compared with the luminance difference of the alignment layer due to rubbing. In particular, since the luminance difference has a value of 0.5 or less, the result is comparable to rubbing, and it can be seen that AC afterimage is significantly reduced.

By forming the alignment layer using the alignment layer forming method as described above, a liquid crystal display device having reduced AC afterimage can be manufactured.

In the method of manufacturing a liquid crystal display according to the present invention, a first substrate and a second substrate facing the first substrate are prepared, an alignment layer is formed on the first substrate and the second substrate by the above-described method, and then the two substrates are prepared. Forming a liquid crystal layer between the substrates.

Preparing the first substrate and the second substrate includes an array process in which a thin film transistor, which is a switching element for driving a liquid crystal layer, is formed on the first substrate, and a color filter process in which a color filter layer is formed on the second substrate. Can be done.

In this case, the process of preparing the first substrate and the second substrate is not limited to the array process and the color filter process, and may be formed by various methods such as performing a color filter process on the first substrate.

Forming the liquid crystal layer on the two substrates on which the alignment layer is formed can also be formed in various ways.

The detailed description of the invention should be construed as illustrative of preferred embodiments rather than as limiting the scope of the invention. Accordingly, the invention is not to be determined by the embodiments described, but should be determined by equivalents to the claims and the appended claims.

According to the present invention, there is an effect of reducing AC afterimage by optimizing process conditions according to characteristics of an optical alignment material, thereby providing a method of forming a high-quality alignment film having reduced AC afterimage.

Claims (10)

Applying a photoalignment agent composition comprising at least one monomer selected from the group consisting of monomers represented by Formula 1 onto a substrate; Inducing a photolysis reaction by irradiating light onto the photo-alignment agent composition; Inducing a crosslinking reaction by applying heat to the photoalignment agent composition; And And post-heating the photo-alignment material composition to form an alignment layer. [Formula 1]

In the formula, R is represented by the following formula (2). (2)

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. The method of claim 1, Irradiating light to the photo-alignment composition to induce a photolysis reaction, and applying a heat to the photo-alignment composition to induce a cross-linking reaction, characterized in that the alignment film is formed at the same time. The method according to claim 1 or 2, Inducing a crosslinking reaction by applying heat to the photo-alignment material composition is an alignment film forming method, characterized in that proceeds to a temperature of 18 ℃ ~ 240 ℃. The method of claim 1, Irradiating light to the photo-alignment material composition formed on the substrate to induce a photolysis reaction, the alignment film forming method, characterized in that carried out in a nitrogen environment. The method of claim 1, Inducing the photodegradation reaction by irradiating light to the photo-alignment material composition formed on the substrate is an alignment film forming method, characterized in that for irradiating the polarized ultraviolet light. The method of claim 1, Irradiating energy in the step of inducing a photolysis reaction by irradiating light to the photo-alignment material composition, the alignment film forming method characterized in that for irradiating at 0.05 ~ 3.0J / cm ² in the case of light of 254nm. The method of claim 1, Post-heat treatment of the photo-alignment material composition is 50 to 230 ℃ alignment film forming method, characterized in that performed for 0.1 to 2 hours. The method of claim 1, The photo-alignment agent composition, represented by the formula (1) and R further comprises a monomer having a structure in which two or more R is connected to any one of the functional group selected from the group consisting of ether, ester and garbornyl group connected to each other. An alignment film formation method characterized by the above-mentioned. Preparing a first substrate and a second substrate; Forming an alignment layer on the first substrate and the second substrate; And Forming a liquid crystal layer between the first substrate and the second substrate, Forming the alignment layer on the first substrate and the second substrate is Applying a photoalignment agent composition comprising at least one monomer selected from the group consisting of monomers represented by Formula 1 onto a substrate; Inducing a photolysis reaction by irradiating light onto the photo-alignment agent composition; Inducing a crosslinking reaction by applying heat to the photoalignment agent composition; And And post-heating the photo-alignment material composition to form an alignment layer. [Formula 1]

In the formula, R is represented by the following formula (2). (2)

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. A photo-alignment material composition for producing an alignment film by a light irradiation alignment method comprising at least one monomer selected from the group consisting of monomers represented by the following formula (1). [Formula 1]

In the formula, R is represented by the following formula (2). (2)

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