JP3044043B2 - Photoalignable polymer composition, liquid crystal alignment film and liquid crystal display device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment film used for a liquid crystal display device, and more particularly to a photo-alignable polymer composition constituting the liquid crystal alignment film. The present invention also relates to a liquid crystal alignment film and a liquid crystal display device using the photoalignable polymer composition.

[0002]

BACKGROUND OF THE INVENTION Liquid crystal display devices generally have a uniform brightness and a high contrast ratio.
In order to obtain the ntrast ratio), it is essential to uniformly align the liquid crystal. For this reason, an alignment film is used for a liquid crystal display (LCD). The alignment layer is mainly made of a polymer material and functions as a director for the alignment of liquid crystal molecules. That is, the electric fiel
When the liquid crystal molecules are moved by the application of d) to form an image, the alignment film causes the liquid crystal molecules to be oriented in an appropriate direction.

As a method of forming an alignment film, a rubbing method, a stretching method, and the like have been used until now.
Techniques such as a method and a light irradiation method are known. To date, the most widely used alignment film in the industry is a rubbing alignment film obtained by using a rubbing technique on a polyimide polymer, and the rubbing alignment film is composed of liquid crystal molecules. To induce orientation.

This method is a simple method of rubbing a substrate coated with the above-mentioned polymer with a cloth, is capable of realizing a large area and high-speed processing, and is a method widely used in industry. Since the rubbing alignment film uses polyimide, it has high heat resistance, and has a problem of rubbing since the molecular chain is steel, and also has a pretilt angle (pretilt angle).
The advantage is that the adjustment of e) is simple.

However, since the shape of the microgrooves formed in the alignment film differs depending on the frictional strength between the alignment cloth and the alignment film, the arrangement of the liquid crystal molecules becomes non-uniform, resulting in phase distortion and light scattering. (Light scattering) occurs. In addition, static electricity (ESD) generated by rubbing the polymer surface
ge) is an active matrix liquid crystal display (AM-LCD: acti
ve matrix LCD), resulting in a decrease in contrast ratio and damage to the substrate.

[0006] Depending on the use of the rubbing technique, LC
Difficult to solve the problem of narrow viewing angle, which accounts for a large part of the various disadvantages of D. Therefore, an alignment film using a new structure and an alignment method is required. An alignment processing method proposed to solve the problem of the rubbing method described above is a photo-alignment method.

The photo-alignment method is a method in which a substrate coated with a photo-alignment material is irradiated with linearly polarized ultraviolet rays to give an alignment direction to an alignment film. The orientation direction is constant with respect to the polarization direction of the linearly polarized ultraviolet light. The pretilt direction differs depending on the incident direction of the irradiated ultraviolet rays, and the pretilt angle differs depending on the irradiation energy.
Since the alignment method using light (ultraviolet light) is a non-contact method,
It is a method that can fundamentally solve the problems of impurity transfer and static electricity generation. It is easy to align and suitable for mass production, and not only can the pretilt angle be easily controlled by adjusting the amount of light, but also This is a method that can greatly improve the viewing angle of an active matrix liquid crystal display device by applying an irradiation method, and is a promising next-generation alignment method that is being actively researched and developed.

However, the known photo-alignment method has a disadvantage in that a large amount of time is required for light irradiation because of its low photosensitivity. The photo-alignment film known to date has chalcone-based and cinnamyl as the photo-alignment part.
System, azobenzene system, coumarin (coumar)
In) systems are used, but they all have such a problem.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide an excellent light-emitting device capable of shortening a light irradiation time in the application of a photo-alignment method. An object of the present invention is to provide a photo-alignable polymer composition having photosensitivity. Another object of the present invention is to provide a liquid crystal alignment film having excellent photosensitivity.

Another object of the present invention is to provide a liquid crystal display device having excellent display characteristics.

[0011]

According to a first aspect of the present invention, a polymer material used as a material for a liquid crystal alignment film comprises a photoreactive portion and a polymer main chain. The portion includes a carbon-carbon triple bond and at least two or more benzene rings, and the polymer main chain is any one selected from the group consisting of polyacrylate, polysiloxane, polymethacrylate, polysaccharide, and polyvinyl alcohol. The present invention relates to a polymer composition comprising a polymer substance comprising two substances, wherein the photoreactive portion and the polymer main chain are connected by any one selected from an ether bond and an ester bond. .

Further, the polymer composition of the present invention is characterized by containing a polymer substance having the following structural formulas (1), (2) and (3).

[0013]

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A second embodiment of the present invention relates to a liquid crystal alignment film manufactured using the above-described polymer composition. A third embodiment of the present invention relates to a liquid crystal display device manufactured using the above-described polymer composition. Other objects and advantages of the present invention will be described below, and will be understood by the practice of the present invention. The objects, advantages, and the like of the present invention can be realized by means and combinations described in the claims.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that a photoreactive portion of a polymer substance used as a material for a liquid crystal alignment film is formed by a carbon-carbon triple bond. That is, a photo-alignment material according to a specific embodiment of the present invention increases the sensitivity of photo-alignment, and a carbon-carbon triple bond is used to obtain alignment of liquid crystal molecules using a film made of this material.

Accordingly, various kinds of derivatives are produced by changing the number of benzene rings in the photoreactive portion, the substituents on the benzene ring, the type of polymer of the polymer main chain, and the number of benzene rings between the polymer and carbon-carbon triple bond. Can be obtained by changing the number of carbon atoms. Incidentally, the polymer substance of the present invention contains at least one or more, preferably two or more benzene rings, the polymer main chain polyacrylate, polysiloxane, polymethacrylate,
Polysaccharide, polyvinyl alcohol and the like are used.

The photoreactive portion of the present invention and the polymer main chain are connected via an ester bond or an ether bond. The benzene ring of the photoreaction part is H, F, Cl, CN, C
F ₃ , OCF ₃ , C _n H _{2 n + 1} (n = 1 to 7) and OC _n H
_{2n + 1} (n = 1 to 7) including a substituent selected from the group consisting of

Specific chemical structures of the above-mentioned polymer substances are shown in the following structural formulas 1, 2 and 3.

[0019]

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Here, the above P₁Is polysacharide, or
Polyvinyl alcohol;_TwoIs polyacryle
Or polymethacrylate, P_ThreeIs polysilo
It is a xan. X, Y, and Z in the above structural formula are H,
F, Cl, CN, CF_Three, OCF_Three, C _nH_{2n + 1}(N = 1
7) or OC_nH_{2n + 1}(N = 1 to 7) and k =
0 to 1 and m = 0 to 7.

Next, a method for synthesizing a polymer having the above structural formula will be described in detail. First, in the polymer substance of the above structural formula 1, a carboxylic acid containing a carbon-carbon triple bond and an alcohol at the polymer end are synthesized through a condensation reaction. The specific synthesis reaction is understood through the following reaction formula 1.

[0022]

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The polymer of the structural formula 2 is carbon-
An alcohol containing a carbon triple bond and a carboxylic acid at the terminal of the polymer are synthesized through a condensation reaction. The specific synthesis reaction is understood through the following reaction formula 2.

[0024]

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The polymer represented by the structural formula 3 is synthesized by reacting a double bond group containing a carbon-carbon triple bond with polysiloxane. The specific synthesis reaction is understood through the following reaction formula 3.

[0026]

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[0027]

EXAMPLES Examples for producing a polymer for constituting the photo-alignable polymer composition of the present invention will be described below. The examples described below are for illustration only, and the invention is not limited to the conditions, materials, or devices mentioned below.

[0028]

Example 1 Cellulose p-methoxyphenylpropio
Synthesis of Luic Acid 0.1 mol of p-methoxyphenylpropiolic acid was placed in a 1 liter flask, 0.12 mol of SOCl ₂ was added, and a catalytic amount of DMF (dimethylformamide) was added. After reacting at room temperature for 6 hours, excess SOCl ₂ was removed under reduced pressure.

A solution prepared by dissolving the obtained acid chloride in 50 ml of methylene chloride was mixed with 500 ml of pyridine and 0.04 ml of cellulose.
It was added slowly over 30 minutes to the flask containing 3 moles. Refluxed for 24 hours. This solution was added to methanol 2
Re-precipitated by slowly pouring into liters for 2 hours and filtering. Further, the filtrate was dissolved in a minimum amount of methylene chloride, reprecipitated over methanol, and filtered. The resulting filtrate was dried under vacuum for 24 hours.

In this way, a photo-aligned polymer having polysaccharide and polyvinyl alcohol as main chains was synthesized.

[0031]

Example 2 3- (p-methoxyphenyl) propargy
Synthesis of polyacrylate 0.1 mol of 3- (p-methoxyphenyl) propargyl alcohol was placed in a 1 liter flask and dissolved in 500 ml of methylene chloride, and then DCC (1,3-dicyclohe
0.2 mol of xyl carbodimide) and 0.03 mol of polyacrylic acid. After reacting at room temperature for 24 hours, the solution was slowly poured into 2 liters of methanol over 2 hours to reprecipitate and filtered. Further, the filtrate was dissolved in a minimum amount of methylene chloride, reprecipitated over methanol, and filtered. The resulting filtrate was dried under vacuum for 24 hours.

In this manner, a photo-alignable polymer having a main chain of polyacrylate and polymethacrylate was synthesized.

[0033]

Example 3 2-propyl p-methoxyphenylpropion
Synthesis of Rate Polysiloxane 0.1 mol of p-methoxyphenylpropiolic acid was placed in a 1 liter flask and 500 ml of methylene chloride was added.
Then, 0.2 mol of DCC (1,3-dicyclohexylcarbodiimide) was added, and 0.1 mol of allyl alcohol was added. After reacting at room temperature for 24 hours, water was added for extraction. Methylene chloride was removed from the organic layer under reduced pressure, and recrystallized using an ethyl acetate / hexane solution.

[0034] 0.05 mol of the compound thus obtained is placed in a 1 liter flask, 500 ml of toluene is added, and polymethyl siloxane is added.
After adding 0.02 mol, 0.0001 mol of PtHCl was dissolved in isopropyl alcohol and added. The reaction was performed at 100 ° C. for 24 hours. The solution was slowly poured into 2 liters of methanol over 2 hours to reprecipitate and filtered. Further, the filtrate was dissolved in a minimum amount of methylene chloride, reprecipitated over methanol, and filtered. The resulting filtrate was dried under vacuum for 24 hours.

According to such a method, a photo-alignable polymer having polysiloxane as a main chain was synthesized. Next, a process of manufacturing a liquid crystal alignment film using the polymer material thus manufactured will be described. The polymer synthesized through the above embodiment was dissolved in THF (tetrahydrofuran) to prepare a solution containing 2 to 10 wt% of the photo-alignable polymer, and the solution was spun on an ITO (indium tin oxide) glass substrate. It was coated to form a film having a thickness of 500-2000 °. The film thus formed was dried by heating at 100 to 250 ° C. for 0.1 to 6 hours.

The liquid crystal alignment film was completed by irradiating ultraviolet rays on the coated surface of the film coated with the polymer substance of the present invention to perform photo alignment. At this time, a Mercury lamp of 180 W was used as a light source, and linearly polarized light was formed with a Glan-Thompson polarizer for irradiation. The wavelength was irradiated only at 365 nm or less. The amount of light applied to the coating surface was determined by the irradiation time and the intensity of the light source.

Next, a process of manufacturing a liquid crystal cell for a liquid crystal display device using the alignment film formed through the above process will be described. The two alignment film films manufactured as described above are overlapped with both teflon spacers so that the alignment directions are parallel to each other, and the interval is 5 to 50 μm.
, And liquid crystal was injected using the current state of the capillary. When the cell gap is small, the liquid crystal and the cell are heated to a high temperature (about 100 ° C or higher) to facilitate injection
While maintaining the injection.

In order to evaluate the pretilt angle of the liquid crystal cell manufactured as described above, the pretilt angle of the liquid crystal cell induced by the alignment film was measured by a crystal rotation method using a test apparatus as shown in FIG. It was measured. (Li
quid Cristal Applicationsand Uses.vol.3, Birendra B
ahadur, World Scientific, 1992) In FIG. 1, reference numeral 1 denotes an ultraviolet light source, 2 denotes a polarizer, 3 denotes a lens, 4 denotes a linearly polarized parallel light, 5 denotes a liquid crystal alignment film,
6 represents a cell holder.

The alignment films of the examples according to the present invention exhibited characteristics as shown in Table 1 below.

[0040]

[Table 1]

As can be seen from Table 1 above, the alignment film of the present invention exhibits excellent alignment characteristics and does not require a large amount of light to obtain an appropriate range of pretilt angle. Additional advantages and variations will be apparent to those skilled in the art. Accordingly, the invention, in its broader aspects, is not limited to the specific details and representative devices shown and described herein.

Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof. In addition, the present invention is not limited to the above-described embodiments, and a person having ordinary knowledge in the technical field to which the present invention pertains may have various modifications within the scope of the technical idea of the present invention and the scope of the following claims. Modifications and variations are, of course, possible.

[0043]

As described above, according to the present invention, the alignment process is simple, suitable for mass production, and the pretilt angle can be easily controlled by adjusting the amount of light to be irradiated at the time of photo alignment. Instead, by applying a complex light irradiation method capable of varying the amount of light and controlling the pretilt angle, the viewing angle in the active matrix liquid crystal display device can be greatly improved.

In particular, the photo-alignable polymer composition of the present invention comprises
Because of high photosensitivity, time required for light irradiation can be saved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an apparatus for measuring a pretilt angle of a liquid crystal alignment film containing a photoalignable polymer composition of the present invention.

[Explanation of symbols]

 1: Ultraviolet light source 2: Polarizer 3: Lens 4: Parallel polarized light 5: Liquid crystal alignment film 6: Cell holder

Continuing on the front page (72) Inventor Lee Kyun Joan Gyeonggi-Do 431-080 Aniang-Shi Donggang-gu Hogyeh-Dong 555 (72) Inventor Kim Tae-min Korea Gyeonggi-Do 431-080 Anyang-Shi Donggang- Gu Ho Guy Dong 555 (72) Inventor Lee Hyeok Jin Republic of Korea Gyeonggi-do 431-080 Aniang-si Donggang-gu Ho Guy-Do Dong 555 (72) Inventor Jo Jeon-gu Ho Republic of Korea Gyeonggi-do 431-080 Anyang-si Donggang-gu Hoguiye-Dong 555 (72) Inventor Kim Jin Yo-ul Republic of Korea Gyeonggi-do 431-080 Aniang-Shi Donggang-gu Hogui-e-Dong 555 (72) Inventor Kim Key-Horn Republic of Korea Gyeonggi-do 431-080 Annie -Shi Dongan-G Hoguje-Dong 555 (72) Inventor Kim Sang Hee Republic of Korea Gyeonggi-do 431-080 Aniang-shi Dongang-gu Hogya-dong 555 (56) References JP-A-6-157441 (JP, A) JP-A-6-306040 (JP, A) JP-A-10- 142608 (JP, A) JP-A-10-125331 (JP, A) JP-A-9-211456 (JP, A) JP-A-9-197406 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1337 520 C08F 2/48 C08F 238/00

Claims (15)

(57) [Claims] 1. A polymer substance used as a material for a liquid crystal alignment film comprises a photoreactive portion and a polymer main chain, wherein the photoreactive portion contains a carbon-carbon triple bond and at least one benzene ring. The polymer main chain is polyacrylate, polysiloxane,
The photoreactive portion and the polymer main chain include any one selected from an ether bond and an ester bond, the material including any one substance selected from the group consisting of polymethacrylate, polysaccharide, and polyvinyl alcohol. A photo-alignable polymer composition characterized by being connected by two bonds. 2. The photo-alignable polymer composition according to claim 1, wherein the photo-alignable polymer composition has the following structural formula. Embedded image Here, the above X, Y, and Z are H, F, Cl, CN, CF
_{3, OCF 3, C n H} 2n + 1 (n = 1~7) or OC _n H
_{2n + 1} (n = 1 to 7), the above k = 0 to 1, and the above m = 0 to 7. 3. The method according to claim 1, wherein the P1 is polysacchalide.
3. The photo-alignable polymer composition according to claim 2, wherein the composition is a ride. 4. The method according to claim 1, wherein P1 is polyvinyl alcohol (poly).
3. The photo-alignable polymer composition according to claim 2, wherein the composition is vinyl alcohol). 5. The photo-alignable polymer composition according to claim 1, wherein the photo-alignable polymer composition has the following structural formula. Embedded image Here, the above X, Y, and Z are H, F, Cl, CN, CF
_{3, OCF 3, C n H} 2n + 1 (n = 1~7) or OC _n H
_{2n + 1} (n = 1 to 7), the above k = 0 to 1, and the above m = 0 to 7. 6. The method according to claim 1, wherein said P2 is a polyacrylate.
6. The photo-alignable polymer composition according to claim 5, which is late). 7. The method according to claim 7, wherein the P2 is polymethacrylate (polyme
The photo-alignable polymer composition according to claim 5, wherein the composition is a thacrylate). 8. The photo-alignable polymer composition according to claim 1, wherein the photo-alignable polymer composition has the following structural formula. Embedded image Here, the above X, Y, and Z are H, F, Cl, CN, CF
_{3, OCF 3, C n H} 2n + 1 (n = 1~7) or OC _n H
_{2n + 1} (n = 1 to 7), the above k = 0 to 1, and the above m = 0 to 7. 9. The method according to claim 9, wherein P3 is a polysiloxane.
9. The photo-alignable polymer composition according to claim 8, wherein the composition is ne). 10. A photo-alignment, wherein the polymer substance used as a material of the liquid crystal alignment film has at least one of the following structural formulas (1), (2) and (3): Polymer composition. Embedded image Here, the above X, Y, Z are H, F, Cl, CN, C
F ₃ , OCF ₃ , C _n H _{2n + 1} (n = 1 to 7) or OC _n H
_{2n + 1} (n = 1 to 7), the above k = 0 to 1, and the above m = 0 to 7. 11. The photo-alignable polymer composition according to claim 10, wherein P _{1 in the} structural formula (1) is one selected from polysaccharide and polyvinyl alcohol. 12. The photo-alignable polymer composition according to claim 10, wherein P _{2 in the} structural formula (2) is one selected from a polyacrylate and a polymethacrylate. 13. The photo-alignable polymer composition according to claim 10, wherein P _{3 in the} structural formula (3) is a polysiloxane. 14. A liquid crystal alignment film manufactured using the polymer composition according to claim 1. Description: 15. A liquid crystal display device manufactured using the polymer composition according to claim 1. Description: