KR20190084520A - High selectivity composition for removing liquid crystal alignment agent - Google Patents

Abstract

The present invention relates to a liquid crystal alignment film removing composition and, more specifically, to a liquid crystal alignment film removing composition which effectively removes impurities and a defective photo-alignment film generated during UV alignment in a manufacturing process of the liquid crystal alignment film from a substrate surface in a short time by using a removing composition comprising a specific solvent such as aminoethylpiperazine, and can be used as a photo-alignment film re-work composition.

Description

TECHNICAL FIELD [0001] The present invention relates to a high selectivity liquid crystal alignment film removing composition,

Disclosed is a method for manufacturing a liquid crystal alignment film using a liquid crystal aligning agent, which can easily remove a defective photo alignment layer and impurities from the substrate in a short period of time when the photo alignment layer is erroneously formed due to poor exposure caused by UV alignment of the liquid crystal alignment layer To a liquid crystal alignment film removing composition.

In a liquid crystal display element, a liquid crystal alignment film plays a role of aligning the liquid crystal in a certain direction. Specifically, the liquid crystal alignment layer acts as a director for the arrangement of liquid crystal molecules, and when the liquid crystal moves due to the electric field to form an image, the liquid crystal alignment film makes a proper orientation. In general, it is essential to uniformly orient the liquid crystal in order to obtain a uniform brightness and a high contrast ratio in a liquid crystal display device.

A rubbing method of applying a polymer film such as polyimide to a substrate such as glass and rubbing the surface with a fiber such as nylon or polyester in a predetermined direction has been used. However, the rubbing method may cause fine dust or electrical discharge (ESD) when the fiber and the polymer film are rubbed, which can cause serious problems in manufacturing the liquid crystal panel.

In order to solve the problem of the rubbing method due to the friction, recently, a UV alignment process has been used. The UV alignment process is an optical alignment method in which anisotropy (anisotropy) is induced in a polymer film by light irradiation and liquid crystals are aligned using the anisotropy. The UV alignment process can improve the CR and the viewing angle due to the improvement of the alignment uniformity and the pretilt angle characteristic (~ 0 degree).

The photo alignment layer is a recently developed product. When the exposure is wrong, it is necessary to remove the alignment layer. However, due to the characteristics of the photo alignment layer, the cross-linking becomes more severe during the exposure and the removal becomes difficult. In addition, if the photo alignment layer is not removed, there is a problem of discarding the glass, which is costly.

Conventionally, a general removal composition or stripper was used when the exposure was wrong, mainly after the UV alignment process. However, there is a problem in that the alignment film is removed only when a conventional stripper or a photo-alignment film is not dissolved during the cleaning liquid treatment and is dipped for a long time.

Accordingly, there is a need for a new photo alignment film removing composition capable of removing a defective liquid crystal alignment film in a short time after the UV alignment process and reducing cost loss to throw away the glass.

The present invention solves the problem that a substrate on which a defective liquid crystal alignment film is formed must be discarded by easily removing defective photo-alignment films and impurities that are not exposed in a short time in the process of manufacturing a liquid crystal alignment film obtained by the UV photo alignment method, Which is economical because the process is simple and does not greatly affect the operation time of the liquid crystal alignment film production process, thereby providing a liquid crystal alignment film removal composition.

The present invention also provides a method for removing by-products of a liquid crystal alignment film using the liquid crystal alignment film-removing composition.

According to one embodiment of the present invention, there is provided a pharmaceutical composition comprising 25% or more aminoethylpiperazine,

There is provided a composition for removing a liquid crystal alignment film used for removing impurities and a bad photo alignment layer which are generated during UV alignment of a polyimide or polyimide precursor in a process for producing a liquid crystal alignment film comprising a precursor of polyimide or polyimide.

The impurity is generated in the step of UV-aligning the precursor of polyimide or polyimide using a 240 nm cut filter, a 240 to 313 nm band path filter, or a Deep UV process.

By using the composition for removing a liquid crystal alignment film according to the present invention, the impurities of the polyimide or polyimide and the defective photo alignment layer can be removed from the substrate within at least 3 minutes.

In addition, the liquid crystal alignment film removing composition of the present invention may further include tetramethylammonium hydroxide.

Such a liquid crystal alignment film-removing composition may comprise at least one selected from the group consisting of an alkylene glycol compound having a viscosity of 10 cP or less and a boiling point of at least 150 ° C, a polar solvent having a viscosity of 5 cP or less and a boiling point of 100 ° C or more, and water; As shown in FIG.

Preferably, the liquid crystal alignment film removing composition comprises: a) 100% by weight of aminoethyl piperazine;

b) from 70 to 90% by weight of aminoethylpiperazine and from 10 to 30% by weight of tetramethylammonium hydroxide;

c) an alkylene glycol compound having a viscosity of 10 cP or less and a boiling point of at least 150 ° C, a polar solvent having a viscosity of 5 cP or less and a boiling point of 100 ° C or more, and water From 70 to 10% by weight of at least one component selected from or

d) an alkylene glycol-based compound having 30 to 70% by weight of aminoethylpiperazine, 10 to 20% by weight of tetramethylammonium hydroxide, a viscosity of 10 cP or lower and a boiling point of at least 150 ° C, A polar solvent at least 100 ° C, and water; and 10 to 30% by weight of at least one selected from the group consisting of water.

The alkylene glycol compound may be at least one selected from the group consisting of diethylene glycol t-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether , Ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.

The polar solvent is selected from the group consisting of ethyl lactate, butyl lactate, isopropyl lactate, hydroxyl acid ester, N-methylpyrrolidone, N-ethylpyrrolidone, N-methylformamide, At least one member selected from the group consisting of imidazolidinone, dimethylsulfoxide, dimethylacetamide, dimethylformamide, and tetramethylenesulfone.

Wherein the liquid crystal alignment layer is formed by coating a substrate with a liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide and a polyimide precursor, and firing the liquid crystal alignment layer to form a polyimide film; And irradiating the substrate on which the polyimide film is formed with polarized radiation to conduct a UV alignment process.

The polyimide precursor may include a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).

[Chemical Formula 1]

(2)

(In the above formulas (1) and (2)

X ¹ and X ² are each independently a tetravalent organic group derived from a hydrocarbon having 4 to 20 carbon atoms or at least one of the tetravalent organic groups is substituted with halogen or one or more -CH ₂ - Is a tetravalent organic group substituted with -O-, -S-, -CO- or -SO- so as not to be directly connected,

R ¹ to R ⁴ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,

R ⁵ to R ⁷ are each independently a halogen, a cyano group, an alkenyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkoxy group or a fluoroalkyl group,

L ¹ is -O-, -O-CH ₂ -O-, -O-CH ₂ CH ₂ -O- or -O-CH ₂ CH ₂ CH ₂ -O-,

p, q and r are each independently an integer of 0 to 4,

and n is an integer of 1 or 2.)

According to another embodiment of the present invention, there is provided a method for removing a by-product of a liquid crystal alignment film, comprising the step of removing an impurity or a bad photo alignment layer which occurs upon UV alignment of a polyimide or polyimide precursor with the liquid crystal alignment film removing composition to provide.

In the present invention, in the step of removing the impurities and the defective photo alignment layer which are generated when the exposure is wrong in the UV alignment during the process of manufacturing the liquid crystal alignment layer, By using a composition containing a solvent, impurities of the liquid crystal alignment film and the polyimide or polyimide precursor can be easily removed from the substrate in a short time. Therefore, the present invention solves the problem of improving the processability of a liquid crystal alignment film and disposing a glass including a conventional defective photo alignment film, thereby realizing cost reduction.

FIG. 1 is an electron micrograph showing a result obtained by removing a defective photo alignment layer from a substrate using a composition for removing alignment layers of Example 1 of the present invention and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in more detail. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Also, " comprising "as used herein should be interpreted as specifying the presence of particular features, integers, steps, operations, elements and / or components, It does not exclude the presence or addition of an ingredient.

According to a preferred embodiment of the present invention, in a process for producing a liquid crystal alignment film comprising at least 25% by weight of aminoethylpiperazine and containing a precursor of polyimide or polyimide, the UV alignment of the precursor of polyimide or polyimide There is provided a composition for removing a liquid crystal alignment film used for removing an impurity and a bad photo alignment layer which are generated when the liquid crystal alignment film is removed.

In general, a liquid crystal alignment layer is formed by coating a polyimide precursor solution such as a polyamic acid or a polyamic acid ester on a substrate, heat-treating the substrate, converting the polyimide into a polyimide, and aligning the liquid crystal alignment layer. At this time, if the rubbing of the alignment film and the exposure of the photo alignment film are wrong, the alignment film should be removed and then used again.

Conventional rubbing alignment films can be removed by strippers or the like, but the photo alignment films are difficult to remove due to excessive cross-linking, unlike the rubbing alignment films. Accordingly, the present invention provides a composition for removing a photo alignment layer in a liquid crystal alignment layer for developing a product capable of rewiring a photo alignment layer.

Accordingly, in the present invention, it is possible to cause a wrong exposure after the UV alignment process in the process of manufacturing the liquid crystal redistribution film. The present invention can effectively remove the defective photo alignment layer from the substrate Can be removed.

That is, the present invention confirms that a defective photo alignment layer can be easily removed from a substrate upon exposure to a certain solvent after irradiation with polarized radiation to a polyimide film obtained by applying and firing a polyimide film or a polyimide precursor Respectively. In this case, impurities of the polyimide film or the polyimide precursor formed on the substrate can also be cleaned and removed.

Particularly, according to the present invention, it is possible to completely remove a photo alignment layer and other impurities within 5 minutes when aminoethylpiperazine represented by the following formula (4) is used or when aminoethylpiperazine and tetramethylammonium hydroxide (TMAH) are present simultaneously Respectively.

[Chemical Formula 4]

Further, in the present invention, the photo alignment layer and impurities can be easily removed from the substrate in a shorter time than in the case of using a cleaning agent or a stripper used for removing a defective photo alignment layer. When the composition for removing an alignment film of the present invention is used, the object to be removed is not a rubbing alignment film but a defective photo alignment film as described above. In addition, the composition containing the specific solvent of the present invention can be used not only for cleaning the surface of the defective photo alignment layer or for removing a part of the defective polymer film, but for dissolving the defective polyimide film formed on the substrate or the polymer comprising the precursor thereof in a short time So that it is possible to completely remove the defective photo alignment layer and impurities from the substrate. Therefore, the present invention can solve the problem of scrapping the defective substrate, and improve the workability in manufacturing the liquid crystal alignment film.

The method of the present invention will be described in more detail.

The present invention is characterized in that the defective photo alignment layer and impurities generated in the UV alignment process of the polyimide or polyimide precursor in the process of manufacturing the liquid crystal alignment layer are removed from the substrate surface with a composition containing a specific solvent.

Such a removal composition of the present invention can be used as a photo-alignment layer re-work composition in a manufacturing process of a photo alignment layer progressing U exposure. At this time, the impurity is generated in the step of UV-aligning the precursor of polyimide or polyimide using a 240 nm cut filter, a 240 to 313 nm band path filter, or a Deep UV process.

The liquid crystal alignment film removing composition of the present invention is characterized by containing aminoethylpiperazine as a main component. Particularly, in the aminoethylpiperazine, the -NH ₂ moiety contained in the terminal moiety is cleaved in the amine composition to form an NH ₂ OH moiety to maximize the polarity, thereby facilitating the removal of the defective liquid crystal alignment film.

The liquid crystal alignment film-removing composition of the present invention may contain at least 25% by weight, preferably at least 30% by weight, of the aminoethylpiperazine, based on the total weight of the composition, Weight% can be included. That is, according to one embodiment of the present invention, it is possible to provide a composition for removing a liquid crystal alignment film comprising aminoethylpiperazine in an amount of 100% by weight, 70 to 90% by weight or 30 to 70% by weight. At this time, when the content of aminoethylpiperazine is 25 wt% or less, there is a problem that life time of the peeling liquid (i.e., composition for removing the liquid crystal alignment film) is reduced.

Further, according to another embodiment of the present invention, the liquid crystal alignment film composition may have a composition of two or more kinds in which at least one other solvent is added to the composition containing aminoethylpiperazine.

Preferably, the present invention further includes tetramethylammonium hydroxide in the liquid crystal alignment film-removing composition, thereby further reducing the impurity removal time.

In the present invention, if necessary, it may further include at least one additional solvent such as an alkylene glycol-based compound having a certain boiling point or a polar solvent, and deionized water may be added thereto. For example, if deionized water is used in the removal composition, 1 to 70% by weight based on the total amount of the total composition may be included.

Therefore, the liquid crystal alignment film removing composition of the present invention

1) Composition of one component consisting of 100% by weight of aminoethylpiperazine

2) The composition of the two components comprising 1) aminoethylpyrazine and tetramethylammonium hydroxide (TMAH)

3) The composition may include one or more additional solvents (including at least one selected from an alkylene glycol compound, a polar solvent and water) in the 1) or 2) composition.

More specifically, the composition for removing a liquid crystal alignment film of the present invention may be prepared by adding aminoethylpiperazine alone or aminoethylpiperazine and tetramethylammonium hydroxide to a removing composition, optionally having a viscosity of 10 cP or less and a boiling point of at least 150 ° C or more, a polar solvent having a viscosity of 5 cP or less and a boiling point of at least 100 ° C or more, and water.

In this case, according to a preferred embodiment, the liquid crystal alignment film removing composition

a) 100% by weight of aminoethylpiperazine;

b) from 70 to 90% by weight of aminoethylpiperazine and from 10 to 30% by weight of tetramethylammonium hydroxide;

c) an alkylene glycol compound having a viscosity of 10 cP or less and a boiling point of at least 150 ° C, a polar solvent having a viscosity of 5 cP or less and a boiling point of 100 ° C or more, and water From 10 to 70% by weight of at least one component selected from or

d) an alkylene glycol-based compound having 30 to 70% by weight of aminoethylpiperazine, 10 to 20% by weight of tetramethylammonium hydroxide, a viscosity of 10 cP or lower and a boiling point of at least 150 ° C, A polar solvent at least 100 ° C, and water; and 10 to 30% by weight of at least one selected from the group consisting of water.

According to another embodiment of the invention, in case c), the liquid crystal alignment film removing composition comprises 30 to 90% by weight of aminoethylpiperazine and an alkylene glycol having a viscosity of 10 cP or lower and a boiling point of at least 150 & Based compound and a polar solvent having a viscosity of 5 cP or less and a boiling point of at least 100 ° C or higher.

In the above c), the liquid crystal alignment film-removing composition preferably contains 30 to 70% by weight of aminoethylpiperazine, an alkylene glycol compound having a viscosity of 10 cP or lower and a boiling point of at least 150 ° C, 10 to 60 wt% of at least one selected from the group consisting of polar solvents having a boiling point of 100 DEG C or higher, and 10 to 30 wt% of water.

According to another embodiment of the invention, in the case of d), the liquid crystal alignment film removing composition comprises 30 to 70% by weight of aminoethylpiperazine aminoethylpiperazine, 10 to 20% by weight of tetramethylammonium hydroxide, 10 to 30 wt% of at least one selected from the group consisting of an alkylene glycol compound having a boiling point of at least 150 ° C and a polar solvent having a viscosity of 5 cP or less and a boiling point of at least 100 ° C or higher.

In addition, in the case of d), the liquid crystal alignment film-removing composition preferably contains 30 to 70% by weight of aminoethylpiperazine, 10 to 20% by weight of tetramethylammonium hydroxide, an alkylene glycol having a viscosity of 10 cP or lower and a boiling point of at least 150 & Based compound and a polar solvent having a viscosity of 5 cP or less and a boiling point of at least 100 ° C, and 10 to 30% by weight of water.

The alkylene glycol compound may be selected from the group consisting of diethylene glycol t-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, ethylene Glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.

The polar solvent may be selected from the group consisting of ethyl lactate, butyl lactate, isopropyl lactate, hydroxyl acid ester, N-methylpyrrolidone, N-ethylpyrrolidone, N-methylformamide, And at least one member selected from the group consisting of 2-imidazolidinone, dimethylsulfoxide, dimethylacetamide, dimethylformamide, and tetramethylene sulfone.

The deionized water to be used in the present invention may be those obtained by a general ion exchange resin method.

Further, in the present invention, the step of removing the defective photo alignment layer may be performed according to a method of immersing the substrate on which the liquid crystal alignment layer is formed for a predetermined time, or spraying the removal composition onto the substrate. Specifically, the step of removing the defective photo-alignment layer is performed at a temperature of about 30 to 1000 占 폚 for 3 to 60 minutes, preferably 50 to 70 占 폚, at a temperature of about 30 to 1000 占 폚 for a substrate on which the impurities of polyimide or polyimide and the defective photo- And immersed for 3 to 5 minutes. According to this process, the impurities of the polyimide or the polyimide and the poor photo alignment layer can be removed within one minute. Preferably, when the composition comprises aminoethylpiperazine and tetramethylammonium hydroxide, the above-mentioned impurities and poor photo alignment layer can be all removed within at least 5 minutes.

In the meantime, the method of manufacturing a liquid crystal alignment layer in the present invention may be formed by various methods known in the art, except for the step of removing impurities and a bad photo alignment layer that occur during UV alignment with the composition .

As a non-limiting example, the liquid crystal alignment film can be formed by applying and firing a liquid crystal aligning agent described later on a substrate, and then irradiating light. At this time, the firing and the light irradiation can proceed at the same time, and the light irradiation can be omitted.

For example, in the present invention, the liquid crystal alignment layer may be formed by coating a substrate with a liquid crystal aligning agent containing at least one polymer selected from the group consisting of polyimide and polyimide precursors, and firing the liquid crystal aligning agent to form a polyimide film. And irradiating the substrate on which the polyimide film is formed with polarized radiation to conduct a UV alignment process. If defects occur during the exposure by UV alignment in this process, the impurities of the polyimide or the polyimide and the defective photo alignment layer are removed as the substrate by the above-described composition.

The liquid crystal alignment film is formed on the surface of the polyimide film through the UV alignment process. Since a small amount of UV decomposition substance exists on the surface of the alignment film, a cleaning process is performed in order to remove impurities from the polymer surface of the alignment film do. The composition used in the washing step is not particularly limited, and materials known in the art can be used. Further, in the present invention, if necessary, the polyimide film may further be subjected to a cleaning process before the UV alignment, and the method is not limited and a method well known in the art can be used.

Further, in the step of forming the polyimide film, the baking process includes a soft or hard baking process. However, the firing process of the present invention is not limited to a large extent because all the general methods can be used. If necessary, both the soft baking and the hard baking process can be performed.

For example, various substrates used in the technical field of the present invention may be used as the substrate on which the liquid crystal alignment layer is to be formed, and various methods known to those skilled in the art may be employed as the application method . As a non-limiting example, the liquid crystal aligning agent may be applied by a method such as screen printing, offset printing, flexographic printing, ink jet, or the like.

Thereafter, the previously prepared coating film is baked. The firing can be performed at a temperature of about 50 캜 to 300 캜 by heating means such as a hot plate, a hot air circulation path, and an infrared ray furnace. The soft baking process may be performed at a temperature of about 70 ° C for 100 seconds to 5 minutes. When the hard baking process is performed, the soft baking process may be performed at a temperature of about 230 ° C for 1000 seconds.

Through such a baking step, the repeating units represented by formulas (1) and (3) in the polymer contained in the liquid crystal aligning agent can be imidized. The polymer can exhibit a remarkably improved imide conversion ratio as compared with the conventional polymer including the imidized repeating unit represented by the formula (2).

After the firing process, the fired film prepared above may be irradiated with light according to a desired orientation direction to impart liquid crystal alignability. That is, as polarized radiation is irradiated onto the liquid crystal alignment film obtained by using the polyimide or a precursor thereof, the alignment film reacts anisotropically to effect light distribution. Accordingly, the step of irradiating the polarized radiation may irradiate the liquid crystal alignment film with ultraviolet light or visible light having a wavelength of 150 to 450 nm, and linearly polarized light in the vertical or oblique direction may be irradiated to the alignment film. The amount of exposure upon ultraviolet irradiation may be about 0.25 to 1 J / cm < ² >.

The step of drying the cleaned substrate after completion of the cleaning step is not limited to the conditions, but the spin drying or oven drying step may be performed at a temperature of about 230 캜 for 1000 seconds.

In addition, the cell laminating process may include a Dummyl Cell laminating process, an IPC cell laminating process, and the method is not limited.

In the present invention, the composition of the liquid crystal aligning agent in the step of forming the polyimide film may be provided through various methods known in the technical field of the present invention.

As a non-limiting example, the above-mentioned polymer may be dissolved or dispersed in an organic solvent to provide a liquid crystal aligning agent.

Specific examples of the organic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2- Dimethyl sulfoxide, dimethyl sulfoxide, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide,? -Butyrolactone, 3-methoxy-N, N-dimethylacetamide, N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, 1,3-dimethyl- imidazolidinone, ethylamylketone, methylnonylketone, , Methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme and 4-hydroxy-4-methyl-2-pentanone. These may be used alone or in combination.

The liquid crystal aligning agent may further include other components besides the polyimide-based polymer and the organic solvent. As a non-limiting example, when the liquid crystal aligning agent is applied, the uniformity of the film thickness and the surface smoothness are improved, the adhesion between the liquid crystal alignment film and the substrate is improved, the dielectric constant and the conductivity of the liquid crystal alignment film are changed, An additive capable of increasing the denseness of the liquid crystal alignment film may be further included. Examples of such additives include various solvents, surfactants, silane compounds, dielectrics, and crosslinking compounds.

The polymer structure of the polyimide or its precursor used for obtaining the liquid crystal aligning agent is not particularly limited, and any structure capable of forming a polyimide-based polymer film well known in the art can be used.

For example, an aromatic diamine compound having a functional group and an aromatic tetracarboxylic acid anhydride can be used. The polyimide film may also be prepared by including repeating units of polyamic acid.

In the present invention, preferred examples of the polyimide precursor may include a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).

Further, the polyimide may be a polymer in which at least a part of the repeating units of the polyimide precursor is imidized.

Preferably, the polyimide precursor contains the repeating unit of Formula 1 in an amount of 50 to 95 mol%, and the repeating unit of Formula 2 may be contained in an amount of 5 to 50 mol%.

[Chemical Formula 1]

(2)

(In the above formulas (1) and (2)

X ¹ and X ² are each independently a tetravalent organic group derived from a hydrocarbon having 4 to 20 carbon atoms or at least one of the tetravalent organic groups is substituted with halogen or one or more -CH ₂ - Is a tetravalent organic group substituted with -O-, -S-, -CO- or -SO- so as not to be directly connected,

R ¹ to R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms,

R ⁵ to R ⁷ are each independently a halogen, a cyano group, an alkenyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkoxy group or a fluoroalkyl group,

L ¹ is -O-, -O-CH ₂ -O-, -O-CH ₂ CH ₂ -O- or -O-CH ₂ CH ₂ CH ₂ -O-,

p, q and r are each independently an integer of 0 to 4,

and n is an integer of 1 or 2.)

For reference, the following terms can be defined as follows, unless otherwise specified.

Examples of the hydrocarbon having 4 to 20 carbon atoms include alkane having 4 to 20 carbon atoms, alkene having 4 to 20 carbon atoms, alkyne having 4 to 20 carbon atoms, cycloalkane having 4 to 20 carbon atoms, Cycloalkene having 4 to 20 carbon atoms, arene having 6 to 20 carbon atoms, or at least one of the ring-shaped hydrocarbons is a fused ring sharing two or more atoms, or one of them Or more hydrocarbons may be chemically bonded hydrocarbons. Specific examples of the hydrocarbon having 4 to 20 carbon atoms include n-butane, cyclobutane, 1-methylcyclobutane, 1,3-dimethylcyclobutane, 1,2,3,4-tetramethylcyclobutane, cyclopentane, cyclohexane , Cycloheptane, cyclooctane, cyclohexene, 1-methyl-3-ethylcyclohexene, bicyclohexyl, benzene, biphenyl, diphenylmethane, 2,2- , 4-tetrahydronaphthalene, 1,6-diphenylhexane, and the like.

The alkyl group having 1 to 10 carbon atoms may be a straight chain, branched chain or cyclic alkyl group. Specifically, the alkyl group having 1 to 10 carbon atoms is preferably a straight chain alkyl group having 1 to 10 carbon atoms; A straight chain alkyl group having 1 to 5 carbon atoms; Branched or cyclic alkyl group of 3 to 10 carbon atoms; Or a branched or cyclic alkyl group having 3 to 6 carbon atoms. More specifically, examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, , neo-pentyl group, cyclohexyl group and the like.

The alkoxy group having 1 to 10 carbon atoms may be a straight chain, branched chain or cyclic alkoxy group. Specifically, the alkoxy group having 1 to 10 carbon atoms is preferably a straight chain alkoxy group having 1 to 10 carbon atoms; A straight chain alkoxy group having 1 to 5 carbon atoms; A branched or cyclic alkoxy group having 3 to 10 carbon atoms; Or a branched or cyclic alkoxy group having 3 to 6 carbon atoms. More specifically, examples of the alkoxy group having 1 to 10 carbon atoms include a methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, iso-butoxy group, iso-pentoxy group, neo-pentoxy group or cycloheptoxy group.

The fluoroalkyl group having 1 to 10 carbon atoms may be one in which at least one hydrogen of the alkyl group having 1 to 10 carbon atoms is substituted with fluorine.

The alkenyl group having 2 to 10 carbon atoms may be a straight chain, branched chain or cyclic alkenyl group. Specifically, the alkenyl group having 2 to 10 carbon atoms is preferably a straight chain alkenyl group having 2 to 10 carbon atoms, a straight chain alkenyl group having 2 to 5 carbon atoms, a branched alkenyl group having 3 to 10 carbon atoms, a branched alkenyl group having 3 to 6 carbon atoms, A cyclic alkenyl group having 5 to 10 carbon atoms or a cyclic alkenyl group having 6 to 8 carbon atoms. More specifically, examples of the alkenyl group having 2 to 10 carbon atoms include an ethenyl group, a propenyl group, a butenyl group, a pentenyl group, and a cyclohexenyl group.

The halogen may be fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

A multivalent organic group derived from any compound means a residue in which a plurality of hydrogen atoms bonded to any compound are removed. As an example, a tetravalent organic group derived from cyclobutane means a residue in which any four hydrogen atoms bonded to cyclobutane are removed.

는 해당 부위의 수소가 제거된 형태의 잔기를 의미한다. 예를 들어,

는 사이클로부탄의 1, 2, 3 및 4번 탄소에 결합된 수소 원자 4개가 제거된 형태의 잔기, 즉 사이클로부탄에서 유래한 4가의 유기기 중 어느 하나를 의미한다. In the present specification,

Means a residue in which the hydrogen at the site is removed. E.g,

Means a residue of a form in which four hydrogen atoms bonded to carbons 1, 2, 3 and 4 of cyclobutane are removed, that is, a quaternary organic group derived from cyclobutane.

In addition, the polyimide precursor herein may also refer to an ester of a polyamic acid or polyamic acid that can provide a polyimide under suitable conditions.

More specifically, the repeating unit represented by Formula 1 may be a repeating unit formed by reacting a linear diamine with a tetracarboxylic acid or an anhydride thereof. The polyimide precursor according to one embodiment of the present invention can provide a liquid crystal alignment layer including a repeating unit derived from a linear diamine as shown in Formula 1, thereby remarkably improving liquid crystal alignability and reliability.

The repeating unit of the above formula (1) may include a divalent organic group derived from a linear diamine. Accordingly, the two amino groups in the repeating unit of the above formula (1) are respectively substituted at positions 1 and 4 (for example, formula 1-1) or positions 1 and 3 (for example, formula 1-2) , Or positions 3 and 3 of the biphenyl (e.g., formula 1-3), positions 4 and 4 '(e.g., formula 1-4) Position (e. G., Formula 1-5). Specific examples of the repeating unit of the formula (1) may be the same as those of the following formulas (1-1) to (1-5).

[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

[Formula 1-5]

The definitions of X ¹ , R ¹ , R ² , R ⁵ and p in the above formulas 1-1 to 1-5 are as defined in the formula (1).

When the repeating unit represented by the formula (1) is at least one of the repeating units of the formulas (1-1) and (1-4), a polyimide precursor capable of realizing a more stable liquid crystal aligning property can be provided.

On the other hand, the repeating unit of formula (2) may impart a liquid crystal aligning property to the polyimide prepared from the polyimide precursor according to one embodiment of the present invention even in the case of light irradiation with a small exposure dose. Accordingly, the orientation stability and reliability of the repeating unit of Formula 1 can be realized without undesired side reactions. That is, it is possible to provide a liquid crystal alignment layer having excellent physical properties of a photo alignment layer while realizing excellent alignment stability as the rubbing alignment layer, by the repeating units of the formulas (1) and (2).

In order to realize excellent physical properties of the photo alignment layer while realizing such excellent orientation stability and reliability, the polyimide precursor according to one embodiment has a repeating unit represented by the formula (1) in an amount of 50 to 95 mol% And the repeating unit represented by the formula (2) may be contained in an amount of 5 to 50 mol%.

Since the polyimide precursor according to one embodiment can be prepared from a tetracarboxylic acid or an anhydride thereof known in the art, X ¹ and X ² in the repeating units of the above formulas (1) and (2) And may be various tetravalent organic groups.

For example, X ¹ and X ² may each independently be a tetravalent organic group represented by the following formula (3).

(3)

In Formula 3,

R ⁸ to R ¹¹ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms,

L ² is -O-, -S-, -CO-, -SO-, -C (CF ₃ ) ₂ - or -COO-CH ₂ CH ₂ -OCO-.

At least a part of X ¹ and X ² may be a tetravalent organic group represented by the following general formula (3-1) in the general formula (3).

[Formula 3-1]

In the above formula (3-1), the definitions of R ⁸ to R ¹¹ are as defined in formula (3).

As described above, the repeating unit of formula (1) wherein X ¹ is a tetravalent organic group of formula (3-1) or the repeating unit of formula ( ^{2) wherein} X ² is a tetravalent organic group of formula (3-1) is easily decomposed by light irradiation, Can be easily implemented. In order to more effectively ensure this effect, the sum of the repeating unit of formula (1) wherein X ¹ is a tetravalent organic group of the above formula (3-1) and the repeating unit of the formula ( ² ) wherein X ² is a tetravalent organic group of the above formula Can be adjusted to 60 to 100 mol% based on the repeating units.

The polyimide precursor according to one embodiment may be a polyamic acid or a polyamic acid ester. In the case where the polyimide precursor is a polyamic acid, R ¹ to R ⁴ in the repeating units of the formulas (1) and (2) may be hydrogen. In the case of polyamic acid ester, at least a part of R ¹ to R ⁴ is an alkyl group having 1 to 10 carbon atoms Lt; / RTI >

On the other hand, in the repeating units of the above formulas (1) and (2), the diamine-derived phenylene group may be substituted with R ⁵ , R ⁶ or R ⁷ . In the phenylene group, a carbon atom not substituted by R ⁵ , R ⁶ or R ⁷ may be bonded to hydrogen. In each of the plurality of repeating units represented by the general formula (1), each R ⁵ may be the same or different, and similarly, in the plurality of repeating units represented by the general formula (2), each of R ⁶ and R ⁷ may be the same or different from each other.

The polyimide precursor according to one embodiment may be prepared to have an appropriate degree of polymerization according to desired properties. In one example, the polyimide precursor may be prepared to have a weight average molecular weight of 1,000 to 200,000 g / mol. It is possible to provide a liquid crystal alignment film exhibiting good physical properties within such a range.

According to another embodiment of the present invention, there is provided a method for removing a by-product of a liquid crystal alignment layer, which comprises removing an impurity or a bad photo alignment layer which occurs upon UV alignment of a polyimide or polyimide precursor with the liquid crystal alignment film removing composition Can be provided.

Therefore, the present invention can remove impurities or poor photo alignment layers that occur during UV alignment in a shorter time than in the prior art, thereby improving the processability and economy and maintaining the performance of the liquid crystal alignment layer.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. However, this is provided as an example of the invention, and the scope of the invention is not limited thereto in any sense.

< Example  1>

30% by weight of aminoethylpiperazine, 10% by weight of tetramethylammonium hydroxide and 60% by weight of DMSO were mixed to prepare a composition for removing a photo alignment layer.

< Example  2>

80% by weight of aminoethylpiperazine, 10% by weight of tetramethylammonium hydroxide and 10% by weight of diethylene glycol monobutyl ether (BDG) were mixed to prepare a composition for removing a photo alignment layer.

< Example  3>

100% by weight of aminoethylpiperazine was used as a composition for removing a photo alignment film.

< Example  4>

40% by weight of aminoethylpiperazine, 20% by weight of tetramethylammonium hydroxide, 20% by weight of diethylene glycol monobutyl ether (BDG) and 20% by weight of deionized water were mixed to prepare a composition for removing a photo alignment layer.

< Example  5>

50% by weight of aminoethylpiperazine, 10% by weight of tetramethylammonium hydroxide, 30% by weight of NMP and 10% by weight of deionized water were mixed to prepare a composition for removing a photo alignment layer.

< Comparative Example  1>

10% by weight of tetramethylammonium hydroxide and 90% by weight of DMSO were mixed to prepare a composition for removing a photo alignment layer.

< Comparative Example  2>

10% by weight of tetramethylammonium hydroxide, 40% by weight of DMSO and 50% by weight of NMP were mixed to prepare a composition for removing a photo alignment layer.

< Experimental Example >

Liquid crystal Orientation agent  And The liquid crystal cell  Produce

(1) Preparation of liquid crystal aligning agent

The polyimide polymer (Mw: 23000 to 27000) was dissolved in a mixed solvent of NMP and n-butoxyethanol in a weight ratio of 8: 2 at a ratio of 5% by weight of solids. Then, the solution thus obtained was pressure-filtered through a filter having a pore size of poly (tetrafluorene ethylene) of 0.2 占 퐉 to prepare a liquid crystal aligning agent.

(2) Production of liquid crystal cell

Using the liquid crystal aligning agent prepared above, a liquid crystal cell was prepared as follows.

A substrate having a comb-shaped IPS (in-plane switching) mode ITO electrode pattern having a thickness of 60 nm, an electrode width of 3 mu m and an inter-electrode gap of 6 mu m is formed on a rectangular glass substrate having a size of 2.5 cm x 2.7 cm And a glass substrate (upper plate) having no electrode pattern were coated with a liquid crystal aligning agent by a spin coating method.

Subsequently, the substrate coated with the liquid crystal aligning agent was placed on a hot plate at about 70 占 폚 for 1000 seconds to be dried, and then hard baked in an oven at about 230 占 폚 for 1000 seconds to obtain a polyimide coating film having a thickness of 0.1 占 퐉.

In order to orient the thus obtained coating film, ultraviolet rays of 254 nm were irradiated at an exposure amount of 0.25 to 1 J / cm ² using an exposure machine having a linear polarizer attached to each coating film of the upper and lower plates.

At this time, a substrate on which a defective liquid crystal alignment layer was formed on the composition for a photo alignment layer of the above Comparative Examples and Examples was impregnated with impurities generated during UV alignment of the polyimide or polyimide precursor and the defective photo alignment layer And the substrate was cleaned and the alignment film removing process was performed (strip condition: 70 ° C, 10 minutes). When the above process was completed, it was dried in an oven at 70 DEG C for 60 seconds.

Thereafter, a sealing agent impregnated with a ball spacer having a size of 3 mu m was applied to the edge of the upper plate of the substrate except the liquid crystal injection hole. Then, the alignment films formed on the upper plate and the lower plate face each other and aligned so that their alignment directions are aligned with each other. Then, the upper and lower plates are bonded together and the sealing agent is cured to manufacture empty cells. Then, liquid crystals were injected into the empty cells to prepare IPS mode liquid crystal cells.

<Confirmation of removal state of liquid crystal alignment film>

After using the photo alignment layer compositions of Comparative Example 1 and Example 1, it was confirmed whether or not the photo-alignment layer was removed from the substrate. The results are shown in Fig.

Referring to FIG. 1, it can be seen that the conventional method consists only of the composition of TMAH and DMSO, and the photo-alignment layer is not removed from the substrate but remains as an impurity. On the other hand, Example 1 confirmed that the alignment layer was completely removed from the substrate.

&Lt; Evaluation of characteristics of liquid crystal alignment film &

Film anisotropy, film uniformity, black level, and after-image residual ratio were measured by the following method using the compositions for removing liquid crystal alignment films used in each of the Examples and Comparative Examples.

In addition, when the alignment process is performed again after removing the alignment film, the comparison result of the alignment film characteristics between the comparative example and the example Table 1 shows the results.

(1) Anisotropy evaluation

The anisotropy of the liquid crystal focusing film was evaluated by the AxoStep method.

(Evaluation standard)

1: Reduced anisotropy value by more than 10% after cleaning

2: Reduced anisotropy value within 10% after cleaning

3: Anisotropy value is the same level as before cleaning

4: Anisotropy value increased within 10% after cleaning

5: Anisotropy value increased more than 10% after cleaning

(2) Evaluation of film uniformity

The film uniformity of the liquid crystal focusing film was evaluated by the AFM method.

(Evaluation standard)

1: Surface roughness value increased by more than 10% after cleaning

2: Surface roughness value increased by 10% after cleaning

3: The surface roughness value is the same level as before cleaning

4: Reduced surface roughness value within 10% after cleaning

5: Reduced surface roughness value by more than 10% after cleaning

(3) Black level evaluation

Black level of liquid crystal focusing film was evaluated by PR-880 method.

(Evaluation standard)

1: Reduction of black value by more than 10% after cleaning

2: Increase of black value within 10% after cleaning

3: Black value is the same level as before cleaning

(4) Evaluation of fluctuation rate of AC residual image

After applying a voltage of AC 12 V for 60 seconds, 24 hours, the AC after-image variation ratio of the liquid crystal focusing film was evaluated by the PR-800 method.

(Evaluation standard)

1: Level of fluctuation of AC residual after cleaning is more than 100%

2: Level of change of AC afterglow after cleaning is more than 30%

3: Compared with before cleaning, the afterglow change rate at the same level (20% change rate)

4: Level of fluctuation of AC residual after cleaning is less than 10%

5: Level of fluctuation of AC residual after cleaning is less than 5%

Test Sample Anisotropic evaluation Film uniformity Black level AC afterimage Comparative Example 1 One One One 2 Comparative Example 2 2 2 One 3 Example 1 3 3 3 4 Example 2 3 3 3 4 Example 3 4 3 3 5 Example 4 4 3 3 5 Example 5 5 3 2 5

As can be seen from Table 1, in Comparative Examples 1 and 2, the results of anisotropy, film uniformity, black level and AC afterglow fluctuation ratio are inferior to the present invention.

However, in the case of Examples 1 to 5 of the present invention, the use of aminoethylpiperazine provided excellent anisotropy, film uniformity, black level and AC afterglow variation rate, and the effect of AC residual phase variation was particularly improved.

Claims (11)

At least 25% by weight aminoethylpiperazine,
A liquid crystal alignment film removing composition used for removing impurities and poor photo alignment layers which are generated during UV alignment of polyimide or polyimide precursors in a process for producing a liquid crystal alignment film comprising a precursor of polyimide or polyimide.
The method of claim 1, wherein the impurity is generated in a step of UV-aligning a precursor of polyimide or polyimide using a 240 nm cut filter, a 240 to 313 nm band path filter, or a Deep UV process Wherein the liquid crystal alignment film is a liquid crystal alignment film.
The liquid crystal alignment film removing composition according to claim 1, wherein the impurities of the polyimide or polyimide and the defective photo alignment layer are removed from the substrate within at least 3 minutes.
The method according to claim 1,
Wherein the removing composition further comprises tetramethylammonium hydroxide.
The liquid crystal alignment film removing composition according to claim 1 or 4,
An alkylene glycol compound having a viscosity of 10 cP or lower and a boiling point of at least 150 ° C, a polar solvent having a viscosity of 5 cP or lower and a boiling point of 100 ° C or higher, and water. Removal composition.
6. The liquid crystal alignment film removing composition according to claim 5,
a) 100% by weight of aminoethylpiperazine;
b) from 70 to 90% by weight of aminoethylpiperazine and from 10 to 30% by weight of tetramethylammonium hydroxide;
c) an alkylene glycol compound having a viscosity of 10 cP or less and a boiling point of at least 150 ° C, a polar solvent having a viscosity of 5 cP or less and a boiling point of 100 ° C or more, and water From 10 to 70% by weight of at least one component selected from or
d) an alkylene glycol-based compound having 30 to 70% by weight of aminoethylpiperazine, 10 to 20% by weight of tetramethylammonium hydroxide, a viscosity of 10 cP or lower and a boiling point of at least 150 ° C, A polar solvent having a temperature of at least 100 캜, and water; and 10 to 30% by weight of at least one selected from the group consisting of water;
Wherein the liquid crystal alignment film removing composition is a liquid crystal alignment film.
6. The method of claim 5, wherein the alkylene glycol compound is selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, Wherein the composition is at least one selected from the group consisting of dipropylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.
6. The method of claim 5, wherein the polar solvent is selected from the group consisting of ethyl lactate, butyl lactate, isopropyl lactate, hydroxyl acid ester, N-methyl pyrrolidone, N-ethyl pyrrolidone, Wherein the composition is at least one selected from the group consisting of 3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, and tetramethylene sulfone.
The liquid crystal display according to claim 1, wherein the liquid crystal alignment layer
Coating and laminating a liquid crystal aligning agent containing at least one polymer selected from the group consisting of polyimide and polyimide precursors on a substrate to form a polyimide film; And irradiating the substrate on which the polyimide film is formed with polarized radiation to perform a UV alignment process.
The composition according to claim 9, wherein the polyimide precursor comprises a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).
[Chemical Formula 1]

(2)

(In the above formulas (1) and (2)
X ¹ and X ² are each independently a tetravalent organic group derived from a hydrocarbon having 4 to 20 carbon atoms or at least one of the tetravalent organic groups is substituted with halogen or one or more -CH ₂ - Is a tetravalent organic group substituted with -O-, -S-, -CO- or -SO- so as not to be directly connected,
R ¹ to R ⁴ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
R ⁵ to R ⁷ are each independently a halogen, a cyano group, an alkenyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkoxy group or a fluoroalkyl group,
L ¹ is -O-, -O-CH ₂ -O-, -O-CH ₂ CH ₂ -O- or -O-CH ₂ CH ₂ CH ₂ -O-,
p, q and r are each independently an integer of 0 to 4,
and n is an integer of 1 or 2.)
A method for removing a by-product of a liquid crystal alignment film, comprising the step of removing an impurity or a defective photo alignment layer that occurs upon UV alignment of a polyimide or polyimide precursor with the liquid crystal alignment film removing composition of claim 1.

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