CN101231466B - Method for forming photosensitive composition, alignment film and optical compensation film - Google Patents

Abstract

The invention provides a photosensitive composition, which comprises a photosensitive polymer, a photosensitive monomer and a photoinitiating compound, can be used as an alignment film or an optical compensation film of a liquid crystal display, and is formed by ultraviolet curing. The repeating unit of the photosensitive polymer has two ethylenic double bonds, the first ethylenic double bond can be polymerized to form a main chain, and the second ethylenic double bond can be subjected to two-stage ultraviolet treatment to form the alignment film. In addition, the photosensitive monomer contains more than two ethylenic double bonds, so that the photosensitivity can be improved and the exposure amount of ultraviolet rays can be reduced.

Description

The formation method of photosensitive composite, alignment film and optical compensation films

Technical field

The present invention relates to photosensitive composite (photosensitive composition), more specifically, relate to the method that photosensitive composite forms alignment film (photoalignment film) or optical compensation films (compensation film).

Background technology

Under the trend that viewing area at display is increasing, thickness is more and more thinner, how further to make liquid crystal alignment, be that LCD is in developing important topic always.In the research in this respect, except the research and development of liquid crystal molecule, the design of alignment film and optical compensation films also is an emphasis.In the prior art, the way of alignment film is carried out orientation with directed brushing method (rubbing) after normally macromolecule membrane being taken shape in substrate.Though this method is simple and orientation is stable, has many problems as follows: the dirt bits that (1) brushing produces pollute, static is residual and scratch.(2) it is narrow that single direction can cause the visual angle, do not meet the trend at wide visual angle.Therefore, carrying out orientation as non-contacting mode how, is a chance of improving above-mentioned shortcoming.The method that several contactless orientations are arranged at present comprises light orientation method, plasma (plasma) Shu Peixiang method and ion beam orientation method.The light orientation promptly is to utilize polarized ultraviolet, cause the optical anisotropy with specific direction irradiation alignment film, make the macromolecule of film surface take place non-even to photopolymerization, isomerization or photodestruciton reaction, make film surface have special directivity, the one-step inducing liquid crystal molecule of going forward side by side is forward arranged.Be exemplified below:

(1) photocrosslinking type (photo-induced crosslinking):

As shown in the formula in, the side chain of polymkeric substance has the two keys of ethylenic, can carry out the ring-closure reaction of [2+2].The aromatic group biphenyl of two amidos (as have) that this type of material use has two amidos reacts the generation polymerization with phthalic anhydride (phthalic anhydride), form film again after forming macromolecule, make the two keys of ethylenic of side chain carry out ring-closure reaction with polarized UV rays at last.Such design mainly is to use two kinds of different polymeric species (main chain is an amidation process, and side chain is the two key cyclizations of ethylenic) to avoid just ruing out of at the first road polymerization procedure functional group of the second road cross-linking reaction.Shortcoming is that the functional group of phthalic anhydride class has color, can influence penetrability.

(2) photoisomerization type (photo-induced isomerization):

As shown in the formula in, azo group changes into cis (cis) from trans (trans) after illumination.Because the polymerization of main chain is an amidation process of using amido and acidic group, so do not influence azo group.Make the azo group isomerization of side chain behind the main chain polymerization formation film with polarized UV rays, make it have the effect of alignment film.But this isomerization is not a non-reversible reaction, and particularly its configuration of heating back will go back to transly from cis, and lose the orientation effect.Therefore lacking thermal stability is the obstacle of this material on alignment film is used.

(3) photo-cleavage type (photo-induced decomposition)

As shown in the formula in, the main chain polymerization makes the cracking of Fourth Ring functional group to have the orientation effect with polarized UV rays after forming film.This kind cracking occurs in main chain, so the rerum natura of the film after the cracking will produce change.This specific character will make the fine setting (substituent kind, number, the degree of polymerization of polymkeric substance, molecular weight or the like) of back have problems.

Above-mentioned three kinds of materials all need high exposure and could form the orientation effect, very big to yield effect, therefore, how a kind of novel materials that overcomes the problems referred to above is provided, the composition that has the height photosensitivity simultaneously, and after low exposure illumination, have good orientation effect, promptly be important goal of the present invention.

Summary of the invention

The invention provides a kind of photosensitive composite, said composition comprises: a.80 to the photosensitive polymer of 90 weight portions, its structural formula is as follows:

M wherein ₁For containing hydrophobic functional groups R ₁Monomer, R ₁Be C ₁-C ₁₂Fluorinated alkyl, a: b is between 0: 100-99: 1; M ₂Structure as follows: R wherein ₂, R ₃Different, have R for comprising heteroatomic segment, making ₄The reactivity of the two keys of ethylenic be higher than and have R ₅The two keys of ethylenic; R ₄, R ₅Be selected from H or CH independently of one another ₃Ar is an aromatic rings; B.5 to the photo-sensitive monomer of 10 weight portions, comprise methacrylate or M ₂And c.2 to the light trigger (photoinitiator) of 10 weight portions.

The present invention also provides a kind of formation method of alignment film, comprises above-mentioned photosensitive composite is dissolved in solvent, forms solution; With solution coat on substrate; Heated substrates desolvates to remove; With polarized UV rays vertical irradiation substrate; And with unpolarized ultraviolet ray with non-perpendicular angular illumination substrate, to form alignment film.

The present invention also provides the method that forms optical compensation films, comprises above-mentioned photosensitive composite is dissolved in solvent, forms solution; With solution coat on substrate; Heated substrates desolvates to remove; This substrate is shone in ultraviolet ray form optical compensation films.

Description of drawings

Fig. 1 is the synoptic diagram that the two-part ultraviolet ray forms alignment film.

Embodiment

The invention provides a kind of photosensitive composite, its composition comprises: a. photosensitive polymer, b. photo-sensitive monomer and c. light trigger.The structural formula of above-mentioned photosensitive polymer is as follows:

M ₁For containing hydrophobic functional groups R ₁Monomer, R ₁Be C ₁-C ₁₂Fluorinated alkyl, a: b is between 0: 100-99: 1.The arrangement mode of this photosensitive polymer comprises segmented copolymer (block copolymer), alternating copolymer (alternative copolymer), random copolymers (random copolymer).The Mn of above-mentioned photosensitive polymer is between 5000-3000 (preferably between 20000-30000), and Mw is between 10000-60000 (preferably between 30000-50000), and Mw/Mn is between 2.Polymer yield is between 5-40%, and preferably between 10-25%, reason is that the productive rate of polymkeric substance improves the solubleness reduction that will make polymkeric substance and improves Mw/Mn.Form the method for above-mentioned polymkeric substance, comprise initial method of light or hot initial method, the present invention is preferably hot initial method, its hot initiator is including but not limited to replacing or unsubstituted organic peroxide (substituted or unsubstituted organicperoxides), azo compound (azo compounds) is preferably the different dibutyronitrile of azo (AIBN).

M ₂Structure as follows:

R ₂, R ₃Different, have R for comprising heteroatomic segment, making ₄The reactivity of the two keys of ethylenic be higher than and have R ₅The two keys of ethylenic.R ₄, R ₅Be selected from H or CH independently of one another ₃R ₂, R ₃Comprise array structure down:

---O---,---R---O---,

---O---R---O---,

Wherein R is C ₁-C ₁₂Alkyl.If R ₂Or R ₃For

Or

Then might form amide-type

Functional group, this functional group can improve the thermal stability and the surface stability of polymkeric substance.

M ₂Ar be aromatic rings such as phenyl, naphthyl, anthryl or heteroaromatic ring.When aromatic rings is phenyl, R ₁With R ₂The position of substitution on this phenyl ring comprises ortho position, a position, contraposition, is preferably contraposition.And can comprise more than one substituting group on the aromatic rings, make by sterically hindered or electronic effect to have R ₄The two keys of ethylenic with have R ₅The two keys of ethylenic have different reactivities.These substituting groups have comprised C _1-6Alkyl and R ₂Or R ₃N, H produce the functional group of hydrogen bond, as ester group, acidic group (hydrogen bond receptor) or hydroxyl, amido (hydrogen-bond donor).Adding hydrogen bond receptor or giving the substituting group of body is in order to increase R ₂Or R ₃Sterically hindered, and then influence the reactivity of polymerization.But synthetic for convenience, be preferably C _1-6Alkyl.Above-mentioned extra substituting group, R ₂With R ₃Relative the position of substitution and R ₂, R ₃Kind, all have R in order to make ₄Or R ₅The reactivity of the two keys of ethylenic produce difference.It should be noted that and have R ₄Or R ₅The reactive difference of the two keys of ethylenic from R ₁With R ₂, be not from R ₄With R ₅Thus, the reactive higher two keys of ethylenic (have R when polymerization ₄Substituting group) will form the skeleton of polymkeric substance, and the two keys of reactive lower ethylenic (has R ₅Substituting group) then be retained the side chain that gets off to become polymkeric substance, ultraviolet ray behind the film to be formed or Cement Composite Treated by Plasma (plasma) are to form alignment film or optical compensation films.Letter, monomer of the present invention has the two keys of two kinds of ethylenic, and a kind of is the two keys of ethylenic that form polymkeric substance, and a kind of is as the two keys of the ethylenic of ultraviolet orientation.

The R that connects Ar ₂, R ₃, can all not link Ar simultaneously with O, this is for fear of the Fries rearrangement reaction.As the R that links Ar with O ₂Or R ₃When producing the Fries rearrangement, another still can carry out polyreaction and unaffected, and the continuation polymerization forms polymkeric substance.And have when producing possible that Fries resets, will produce the reactivity of the two keys of ethylenic of the substituting group (substituting group that links Ar with O) that Fries resets, preferably low than the substituent reactivity that can not produce the Fries rearrangement.Preferred design comprises that the energy of activation that makes polyreaction is lower than the energy of activation of rearrangement reaction, avoids the generation of rearrangement reaction with temperature and reagent; Preferred design is to avoid application can produce the substituting group of rearrangement reaction.

In the present invention, in order further to improve the polymerization speed of photosensitive composite, in composition, add photo-sensitive monomer such as methacrylate or above-mentioned M ₂With light trigger.If adopt M ₂Monomer can reduce the complicacy of photo-sensitive monomer and photosensitive polymer polymerized product.But M ₂Monomer has only the two keys of two ethylenic, for improving degree of crosslinking, can adopt methacrylate with the two keys of multi-ethylenical, as contain diisoamyl tetrol six acrylate (the dipenthaerythiritol hexacrylate of six two keys, DPHA), the diisoamyl tetrol five acrylate (dipentaerythritolpentacrylate that contain five two keys, DPEPA), the isoamyl tetrol tetraacrylate (pentaerythritoltetraacrylate that contains four two keys, PETIA), trimethylolpropane triacrylate (the Trimethylolpropane Triacrylate that contains three two keys, TMPTA) or isoamyl tetrol triacrylate (Pentaerythritol Triacrylate, PETA).These photo-sensitive monomers can improve the photo-hardening speed of photosensitive composite.

In order to make photo-sensitive monomer (b) and photosensitive polymer (a) polymerization, need light trigger.Be applicable to that light trigger of the present invention can be general common light trigger, be preferably acetophenones, the styrax class, the diphenyl ketone, the thioxanthene ketone, the anthraquinone class, or the combination of above-mentioned substance, as 2-hydroxy-2-methyl-1-phenyl-propane-1 ketone (2-hydroxy-2-methyl-1-phenyl-propan-1-one), 4-benzoin-4-methyldiphenyl base sulfide, 2-benzyl-2-dimethylamino-1-[4-(methyl mercapto) phenyl]-2-morpholine propane-1-ketone, 2,2-diethoxy-2-phenyl acetophenone, 2-methylanthraquinone, the 2-EAQ, 2-tert-butyl group anthraquinone or 2,4-dimethyl thioxanthones.

In a preferred embodiment of the invention, photosensitive polymer accounts for 80 to 90 weight portions, and photo-sensitive monomer accounts for the 5-10 weight portion, and light trigger accounts for the 2-10 weight portion.

After the present invention is dissolved in above-mentioned photosensitive composite solvent and forms solution, with this solution coat on substrate and heated substrates desolvate to remove.Then utilize polarization or unpolarized ultraviolet ray with non-perpendicular angular illumination substrate, vertical or oblique irradiated substrate makes the formation alignment film with polarized UV rays again.Solvent is preferably polar aprotic solvent (polar aprotic solvent) as DMF.This solution coat is preferably method of spin coating in the method for substrate, and the mode of coating can be once to be finished, or earlier with make at a slow speed flow evenly after, again to make uniform film thickness, film thickness be preferably the 0.1-20 millimeter fast.The mode of heated substrates is preferably two-part heating, earlier with lower temperature (90-120 ℃) soft roasting short period (＜15 minutes), again with the roasting firmly long period (＞25 minutes) of higher temperatures (140-170 ℃), removes film thickness after desolvating between the 0.05-10 millimeter.The kind of substrate comprises the glass substrate and the flexible plastic substrates of LCD.Unpolarized ultraviolet light is with lower exposure (0-100mJ/cm ²) irradiation, non-perpendicular angle (the 15-75 degree is preferably 45 degree) is shone this film.Polarized UV rays is with suitable exposure (50-500mJ/cm ²) film on the vertical or non-perpendicular angular illumination substrate, and the alignment film that forms has good quality, can make liquid crystal molecule have the tilt angle of 0-90 degree, angular dimension is according to the type of polymer that forms alignment film.The important key aspect of using the above-mentioned alignment film of two-part ultraviolet ray formation is whether the two keys of ethylenic of side chain participate in polymerization in polymerization process.If have neither part nor lot in polymerization, ultraviolet processing procedure just can make the two keys of the ethylenic that keeps on the side chain produce reaction, reaches the effect of orientation.In addition, photo-sensitive monomer can be accelerated the photo-hardening speed of photopolymer, reduces the exposure intensity and the time of ultraviolet source, can reduce processing procedure cost and faster production.

Alignment film provided by the present invention has following feature: uniformly orientation homogeneity, average anchoring energy (about 10 ^-5Erg/cm ²), thermal stability is (after being heated above 10 ℃ of clear points (clear point) and keeping more than 10 minutes, still has uniform regiospecific, do not destroy regiospecific because of heating) and solvent resistance good, do not destroy regiospecific because of the solvent in the photonasty liquid crystal solution.

In addition, be attached to the alignment film of substrate inboard, directly contact liquid crystal molecule and make its orientation; And be attached to optical compensation films outside the substrate, make the unlikely metal gates reflection that causes in the LCD of surround lighting.And polymkeric substance of the present invention has this two kinds of purposes.The method that forms optical compensation films is as follows: above-mentioned photosensitive composite is dissolved in solvent, behind the formation solution it is coated on the substrate; Then heated substrates desolvates to remove, and with ultraviolet irradiated substrate to form alignment film, coating photoreactivity liquid crystal on alignment film with unpolarized ultraviolet irradiating liquid crystal, makes the formation optical compensation films again.

Preferred embodiment

Embodiment 1-1

The copolymer 1 of methacrylic acid 4-(methacryl amido) phenyl ester (4-(methacrylamido) phenylmethacrylate) and perfluorinate propyl methyl acid esters

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.5g (2mmol), the perfluorinate propyl methyl acid esters (2 of 0.375g (1.4mmol), 2,3,3-tetrafluoropropylmethacrylate) with the AIBN of 0.00875g, be dissolved in behind the DMF of 10mL with exhausted to air bound, after 20 minutes, reactant is slowly splashed into the ether (200mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 1 of 0.374g (productive rate 42.7%) after the filtration.IR (KBr), cm ^-1: broad peak (broad) 3430,3350 (N-H), 1750 (O-C-O-), 1670 (acid amides), 1510,1260,962,945,879,661 (aryl), other signal is as 2940,1410,1390,1320,1200,1170,1130,1100,1002,833,525.

The multipolymer 2 of methacrylic acid 4-(methacryl amido) phenyl ester and perfluorinate propyl methyl acid esters

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.91g (4mmol), the perfluorinate propyl methyl acid esters of 1g (5mmol) and the AIBN of 0.0191g, be dissolved in behind the DMF of 24mL isolated with air, after 40 minutes, reactant is slowly splashed into the ether (200mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 2 of 0.24g (productive rate 12%) after the filtration.IR (KBr), cm ^-1: broad peak 3392 (N-H), 1752 (O-C-O-), 1668 (acid amides), 1508,1253,965,904,664 (aryl), other signal is as 2937,1408,1392,1170,1156,1128,1016,805,712.

The multipolymer 3 of methacrylic acid 4-(methacryl amido) phenyl ester and perfluorinate propyl methyl acid esters

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.399g (1.6mmol), the perfluorinate propyl methyl acid esters of 0.760g (3.8mmol) and the AIBN of 0.0116g, be dissolved in behind the DMF of 5mL isolated with air, after 50 minutes, reactant is slowly splashed into the ether (100mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 3 of 0.062g (productive rate 7%) after the filtration.

The multipolymer 4 of methacrylic acid 4-(methacryl amido) phenyl ester and perfluorinate amyl group methacrylate

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.6g (2.4mmol), the perfluorinate amyl group methacrylate (2 of 0.072g (0.24mmol), 2,3,3,4,4,5,5-octafluoropentyl-methacrylate) with the AIBN of 0.0067g, be dissolved in behind the DMF of 10mL isolated with air, after 165 minutes, reactant is slowly splashed into the ether (100mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 4 of 0.2658g (productive rate 39%) after the filtration.IR (KBr), cm ^-1: broad peak 3440 (N-H), 1750 (O-C-O-), 1670 (acid amides), 1510,1260,964,661 (aryl), other signal is as 2940,1410,1390,1320,1200,1170,1130,1100,1002,816,714,525.

The multipolymer 5 of methacrylic acid 4-(methacryl amido) phenyl ester and perfluorinate amyl group methacrylate

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.4g (1.6mmol), the perfluorinate amyl group methacrylate of 0.342g (1.1mmol) and the AIBN of 0.0074g, be dissolved in behind the DMF of 7mL isolated with air, after 35 minutes, reactant is slowly splashed into the ether (100mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 5 of 0.1985g (productive rate 26.8%) after the filtration.IR (KBr), cm ^-1: broad peak 3420 (N-H), 1750 (O-C-O-), 1670 (acid amides), 1510,1260,966,663 (aryl), other signal is as 2940,1410,1390,1320,1200,1170,1130,1050,1002,810,525.

The multipolymer 6 of methacrylic acid 4-(methacryl amido) phenyl ester and perfluorinate amyl group methacrylate

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.74g (3mmol), the perfluorinate amyl group methacrylate of 0.9g (3mmol) and the AIBN of 0.0164g, be dissolved in behind the DMF of 22mL isolated with air, after 100 minutes, reactant is slowly splashed into the ether (200mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 6 of 0.32g (productive rate 54%) after the filtration.IR (KBr), cm ^-1: broad peak 3392 (N-H), 1752 (O-C-O-), 1668 (acid amides), 1508,1253,965,904,664 (aryl), other signal is as 2937,1408,1392,1170,1156,1128,1016,805,712.

The multipolymer 7 of methacrylic acid 4-(methacryl amido) phenyl ester and perfluorinate amyl group methacrylate

Get methacrylic acid 4-(methacryl amido) phenyl ester of 0.225g (0.9mmol), the perfluorinate amyl group methacrylate of 0.646g (2.2mmol) and the AIBN of 0.0087g, be dissolved in behind the DMF of 5mL isolated with air, after 45 minutes, reactant is slowly splashed into the ether (100mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 7 of 0.181g (productive rate 20.7%) after the filtration.

The multipolymer 8 of methacrylic acid 4-(methacryl amido) phenyl ester and octyl group methacrylate is got methacrylic acid 4-(methacryl amido) phenyl ester of 0.43g (1.7mmol), the 2-Propenoic acid, 2-methyl-, octyl ester (octylmethacrylate) of 0.17g (0.85mmol) and the AIBN of 0.0060g, be dissolved in behind the DMF of 6mL isolated with air, after 60 minutes, reactant is slowly splashed into the ether (100mL) in the stirring under the room temperature in reaction under 80 ℃.Get the co-polymer 8 of 0.0862g (productive rate 14.4%) after the filtration.

Embodiment 1-2

The preparation of alignment film

Get the copolymer 1-8 of 80 weight portions, diisoamyl tetrol six acrylate (DPHA) of 10 weight portions, the light trigger of 5 weight portions respectively and be dissolved in DMF, form photosensitive composition solution.Then the speed rotary coating that above-mentioned solution is changeed with per minute 3500 is to containing the on glass of ITO electrode, with 180 ℃ of bakings 1.5 hours to remove DMF.Then substrate is taken out and returns back to room temperature from baking oven, with the photosensitive composition film on the ultraviolet irradiated substrate of high-pressure sodium lamp generation, as shown in Figure 1.At first, with polarized UV rays inclination 45 this film of degree irradiation (about 50mJ/cm of exposure ²).Afterwards, add Polarizer, with unpolarized ultraviolet vertical irradiation film (the about 50mJ/cm of exposure ²), form alignment film.Above-mentioned polarization and unpolarized ultraviolet wavelength are single wavelength (254nm).Except the TSA processing procedure with single wavelength forms the alignment film, the present invention also can use ultraviolet wave band (270-400nm) to carry out single exposure manufacture process, to form optical compensation films, its exposure is less than 50mJ/cm as 45 these films of degree irradiation that tilt with the polarized UV rays wave band ²

Comparative example

Get copolymer 1-8 and be dissolved in DMF, form photosensitive composition solution.Then the speed rotary coating that above-mentioned solution is changeed with per minute 3500 is to containing the on glass of ITO electrode, with 180 ℃ of bakings 1.5 hours to remove DMF.Then substrate is taken out and returns back to room temperature from baking oven, with polymkeric substance or the copolymer film on the ultraviolet irradiated substrate of high-pressure sodium lamp generation.At first, with polarized UV rays inclination 45 this film of degree irradiation (about 360mJ/cm of exposure ²).Afterwards, add Polarizer, with unpolarized ultraviolet vertical irradiation film (the about 360mJ/cm of exposure ²).Because Comparative Examples does not have the photonasty monomer and light trigger helps sclerosis, its exposure is much larger than the exposure of the embodiment of the invention.

Claims (14)

1. A photosensitive composition comprising: The photosensitive polymer of a.80 to 90 weight parts, its structural formula is as follows:

Wherein M ₁ is a group connected to a hydrophobic functional group R ₁ , R ₁ is a C ₁ -C ₁₂ fluorinated alkyl group, and a:b is between 0:100-99:1; The structure of _M2 is as follows:

Wherein R ₂ and R ₃ are different and are chain segments containing heteroatoms, so that the reactivity of the ethylenic double bond with R ₄ is higher than that of the ethylenic double bond with R ₅ , and R ₂ and R ₃ are selected from the following structure:

——O——,——R——O——,

——O—R——O——,

Wherein R is a C ₁ -C ₁₂ alkyl group; and R ₂ and R ₃ connected to Ar are not connected to Ar with O at the same time; R ₄ and R ₅ are each independently selected from H or CH ₃ ; Ar is an aromatic ring; b. 5 to 10 parts by weight of a photosensitive monomer including methacrylate or _M2 ; and c. 2 to 10 parts by weight of a photoinitiator. 2. The photosensitive composition as claimed in claim 1, wherein the methacrylate monomer comprises dipentylthritol hexaacrylate, dipentylthritol pentaacrylate, pentaerythritol tetraacrylate, trihydroxy Methylpropane Triacrylate, or Pentaerythritol Triacrylate. 3. The photosensitive composition as claimed in claim 1, wherein Ar of M ₂ comprises phenyl, naphthyl, anthracenyl, or a heterocyclic aromatic ring. 4. The photosensitive composition as claimed in claim 3, wherein when the aromatic ring Ar is phenyl, the relative positions of R ₂ and R ₃ substituted on the benzene ring are para-position. 5 . The photosensitive composition as claimed in claim 3 , wherein the substituents of the aromatic ring Ar include more than one substituent in addition to R ₂ and R ₃ . 6. The photosensitive composition as claimed in claim 5, wherein the more than one substituent comprises a C ₁ -C ₆ alkyl group. 7. A method for forming an alignment film, comprising: Dissolving the photosensitive composition according to claim 1 in a solvent to form a solution; coating the solution on the substrate; heating the substrate to remove the solvent; irradiating polarized ultraviolet light perpendicularly to the substrate; and The substrate is irradiated with non-polarized ultraviolet light at a non-perpendicular angle to form an alignment film. 8. The method for forming an alignment film as claimed in claim 7, wherein the concentration of the photosensitive polymer in the solution is 0.5-5 wt%. 9. The method for forming an alignment film as claimed in claim 7, wherein the method of coating the solution on the substrate comprises a spin coating method. 10 . The method for forming an alignment film according to claim 7 , wherein the substrate comprises a thin film transistor gate multi-group substrate or a color filter substrate of a liquid crystal display. 11 . 11. The method for forming an alignment film as claimed in claim 7, wherein energy of the polarized ultraviolet rays is less than energy of the unpolarized ultraviolet rays. 12 . The method for forming an alignment film as claimed in claim 7 , wherein the non-perpendicular angle at which the unpolarized ultraviolet rays irradiate the substrate is between 15° and 75°. 13. A method for forming an optical compensation film, comprising: Dissolving the photosensitive composition according to claim 1 in a solvent to form a solution; coating the solution on the substrate; heating the substrate to remove the solvent; The substrate is irradiated with ultraviolet rays to form an optical compensation film. 14. The method for forming an optical compensation film as claimed in claim 13, wherein the ultraviolet rays comprise unpolarized ultraviolet rays or polarized ultraviolet rays.

Images