CN108369358B

CN108369358B - Composition for producing liquid crystal alignment film, liquid crystal alignment film using same, method for producing same, liquid crystal display element having liquid crystal alignment film, and method for producing same

Info

Publication number: CN108369358B
Application number: CN201680071493.5A
Authority: CN
Inventors: 原田佳和
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2015-10-07
Filing date: 2016-10-06
Publication date: 2022-02-25
Anticipated expiration: 2036-10-06
Also published as: KR20180063269A; TW201727339A; TWI722026B; JP6925584B2; WO2017061541A1; JPWO2017061541A1; CN108369358A

Abstract

The present invention provides: a composition for producing a liquid crystal alignment film, which can stably produce an alignment control capability by enlarging the range of the amount of light irradiation and can efficiently obtain a high-quality liquid crystal alignment film. The present invention provides a composition for producing a liquid crystal alignment film, comprising: (A) a side chain polymer having a side chain which exhibits liquid crystallinity in a predetermined temperature range and has a photoreactive group that undergoes photocrosslinking, photoisomerization or photo-Fries rearrangement; (B) an organic solvent; and (C) an additive, the lowest triplet energy of the additive (C) being lower than the lowest triplet energy of the compound derived from the photoreactive group.

Description

Composition for producing liquid crystal alignment film, liquid crystal alignment film using same, method for producing same, liquid crystal display element having liquid crystal alignment film, and method for producing same

Technical Field

The present invention relates to a composition for producing a liquid crystal alignment film, and particularly to a composition for producing a liquid crystal alignment film for a transverse electric field driven liquid crystal display element.

The present invention also relates to a liquid crystal alignment film produced using the composition, particularly a liquid crystal alignment film for a transverse electric field driven liquid crystal display element, a substrate having the liquid crystal alignment film, and a method for producing the liquid crystal alignment film.

The present invention also relates to a liquid crystal display element having the liquid crystal alignment film or the substrate, and a method for manufacturing the same.

In particular, the present invention relates to a composition for producing a liquid crystal alignment film, in particular, a composition for producing a liquid crystal alignment film for a transverse electric field driven type liquid crystal display element, a liquid crystal alignment film produced using the composition or a substrate having the liquid crystal alignment film, a liquid crystal display element having the same, and a method for producing a liquid crystal alignment film, a substrate having the liquid crystal alignment film, or a liquid crystal display element, which are used in a photo-alignment method for aligning a liquid crystal alignment film.

Background

Liquid crystal display elements are known as display devices that are lightweight, thin, and low in power consumption, and have been used for large-sized televisions and the like in recent years, and remarkable progress has been made. The liquid crystal display element is configured by sandwiching a liquid crystal layer between a pair of transparent substrates provided with electrodes, for example. Also, in the liquid crystal display element, an organic film formed of an organic material is used as a liquid crystal alignment film to cause the liquid crystal to assume a desired alignment state between the substrates.

That is, the liquid crystal alignment film is a component of the liquid crystal display element, is formed on the surface of the substrate that is in contact with the liquid crystal and holds the role of aligning the liquid crystal in a specific direction between the substrates. Further, the liquid crystal alignment film is sometimes required to have a function of aligning the liquid crystal in a specific direction, for example, a direction parallel to the substrate, and a function of controlling the pretilt angle of the liquid crystal. The ability of such a liquid crystal alignment film to control the alignment of liquid crystals (hereinafter referred to as alignment control ability) is imparted by performing alignment treatment on an organic film constituting the liquid crystal alignment film.

As a method for aligning a liquid crystal alignment film for imparting alignment controllability, a photo-alignment method is known in addition to a conventional brushing method. The photo-alignment method has the following advantages: compared with the conventional brushing method, the method does not require brushing, does not cause generation of dust or static electricity, and can perform alignment treatment on a substrate of a liquid crystal display element having irregularities on the surface.

In the photo-alignment method, there are various methods of forming anisotropy in an organic film constituting a liquid crystal alignment film by linearly polarized light or collimated light, and aligning liquid crystal according to the anisotropy.

As the photo-alignment method, a decomposition type photo-alignment method, a photo-crosslinking type photo-alignment method, a photo-isomerization type photo-alignment method, and the like are known.

The decomposition type photo-alignment method is: for example, a method of irradiating a polyimide film with polarized ultraviolet light, causing anisotropic decomposition of the polyimide film due to the polarization direction dependency of ultraviolet absorption of the molecular structure, and aligning the liquid crystal with the polyimide remaining without decomposition (see, for example, patent document 1).

The photo-alignment method of the photo-crosslinking type and the photo-isomerization type is as follows: for example, a method of irradiating polyvinyl cinnamate with polarized ultraviolet rays to cause dimerization reaction (crosslinking reaction) of double bond portions of 2 side chains parallel to polarized light and align liquid crystals in a direction perpendicular to the polarization direction (see, for example, non-patent document 1). In addition, when a side chain polymer having azobenzene in the side chain is used, polarized ultraviolet light is irradiated to cause an isomerization reaction of the azobenzene portion of the side chain parallel to the polarized light, and the liquid crystal is aligned in a direction perpendicular to the polarization direction (see, for example, non-patent document 2). Further, patent document 3 discloses a liquid crystal alignment film obtained by using a photo-alignment method based on photo-crosslinking, photo-isomerization, or photo-fries rearrangement.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3893659

Patent document 2: japanese laid-open patent publication No. 2-37324

Patent document 3: WO2014/054785

Non-patent document

Non-patent document 1: m.shadt et al, jpn.j.appl.phys.31,2155(1992).

Non-patent document 2: ichimura et al, chem.rev.100,1847(2000).

Disclosure of Invention

Problems to be solved by the invention

As described above, the photo-alignment method has a significant advantage in that it does not require a rubbing process itself, as compared with a rubbing process which has been industrially used as an alignment treatment method for a liquid crystal display element. In addition, the optical alignment method can control the alignment control ability by changing the irradiation amount of polarized light, compared to the rubbing method in which the alignment control ability by the rubbing is almost constant.

However, when the alignment controllability of the main component used in the photo-alignment method is too sensitive to the irradiation amount of polarized light, the alignment may be incomplete in a part or the whole of the liquid crystal alignment film, and stable liquid crystal alignment may not be achieved.

Accordingly, an object of the present invention is to provide a composition for producing a liquid crystal alignment film, particularly a composition for producing a liquid crystal alignment film for a transverse electric field driven type liquid crystal display element, which can expand a range of light irradiation amount in which alignment controllability can be stably generated and can efficiently obtain a liquid crystal alignment film having good quality.

In addition to or in addition to the above object, an object of the present invention is to provide a liquid crystal alignment film or a substrate having a liquid crystal alignment film produced using the composition, and a liquid crystal display element, particularly a transverse electric field-driven liquid crystal display element, having the liquid crystal alignment film or the substrate.

Further, another object of the present invention is to provide, in addition to or in addition to the above object, a liquid crystal alignment film, a substrate having the liquid crystal alignment film, or a method for manufacturing a liquid crystal display element, particularly a lateral electric field driven liquid crystal display element.

Means for solving the problems

The present inventors have found the following invention.

< 1 > A composition for producing a liquid crystal alignment film, particularly a composition for producing a liquid crystal alignment film for a transverse electric field-driven liquid crystal display element, comprising:

(A) a side chain polymer having a side chain which exhibits liquid crystallinity in a predetermined temperature range and has a photoreactive group that undergoes photocrosslinking, photoisomerization or photo-Fries rearrangement;

(B) an organic solvent; and

(C) an additive agent is added to the mixture,

(C) the lowest triplet energy of the additive is lower than that of the compound derived from the photoreactive group.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a composition for producing a liquid crystal alignment film, particularly a composition for producing a liquid crystal alignment film for a transverse electric field driven liquid crystal display element, which can expand the range of light irradiation amount in which alignment control capability is stably generated and can efficiently obtain a liquid crystal alignment film having good quality.

In addition to or in addition to the above-described effects, the present invention can provide a liquid crystal alignment film or a substrate having a liquid crystal alignment film produced using the composition, and a liquid crystal display element, particularly a transverse electric field-driven liquid crystal display element, having the liquid crystal alignment film or the substrate.

Further, according to the present invention, in addition to or in addition to the above-described effects, it is possible to provide a method for manufacturing a liquid crystal alignment film, a substrate having a liquid crystal alignment film, or a liquid crystal display element, particularly a lateral electric field driven type liquid crystal display element.

Detailed Description

The present application provides: a composition for producing a liquid crystal alignment film, particularly a composition for producing a liquid crystal alignment film for a transverse electric field driven liquid crystal display element, and more particularly a composition for increasing the light irradiation dose range and improving the production efficiency of a liquid crystal alignment film in a photo-alignment method used for the alignment treatment of a liquid crystal alignment film.

In addition, the present application provides: a liquid crystal alignment film produced using the composition, particularly a liquid crystal alignment film for a transverse electric field driven liquid crystal display element, a substrate having the film, and a method for producing the same.

Further, the present application provides a liquid crystal display element having the liquid crystal alignment film or the substrate and a method for manufacturing the same.

< composition for producing liquid Crystal alignment film >

The composition for producing a liquid crystal alignment film of the present application, particularly a composition for producing a liquid crystal alignment film for a transverse electric field driven liquid crystal display element, contains:

(B) an organic solvent; and

(C) and (3) an additive.

Here, the (C) additive is characterized in that the lowest triplet energy thereof is lower than that of the compound derived from the photoreactive group.

By using the composition of the present application, the light irradiation dose range can be expanded and the production efficiency of the liquid crystal alignment film can be improved in the photo-alignment method used for the alignment treatment of the liquid crystal alignment film obtained from the composition.

Side chain type polymer (A)

(A) The side chain polymer is a side chain polymer having a side chain exhibiting liquid crystallinity in a predetermined temperature range. In addition, the side chain has a photoreactive group that undergoes photocrosslinking, photoisomerization, or photo-Fries rearrangement.

(A) The side chain type polymer is preferably reacted with light having a wavelength of 250 to 400nm and exhibits liquid crystallinity at a temperature of 100 to 300 ℃.

(A) The side chain type polymer preferably reacts with light having a wavelength ranging from 250nm to 400 nm.

(A) The side chain type polymer preferably has a mesogenic group in order to exhibit liquid crystallinity at a temperature range of 100 to 300 ℃.

(A) The side chain type polymer has a side chain having a photoreactive group bonded to a main chain thereof, and is capable of inducing a crosslinking reaction, an isomerization reaction, or a photo-fries rearrangement by light. The structure of the side chain having a photoreactive group is not particularly limited, and a structure in which a crosslinking reaction or a photo-fries rearrangement occurs by light induction is preferable, and a crosslinking reaction occurs more preferably. In this case, even if exposed to external stress such as heat, the achieved alignment controllability can be stably maintained for a long period of time. The structure of the side chain type polymer capable of exhibiting liquid crystallinity is not particularly limited as long as it satisfies the above characteristics, and it is preferable that the side chain structure has a rigid mesogenic component. In this case, when the side chain polymer is formed into a liquid crystal alignment film, stable liquid crystal alignment can be obtained.

The structure of the polymer may be, for example, as follows: a main chain and a side chain bonded thereto, the side chain having a mesogenic component such as biphenyl, terphenyl, phenylcyclohexyl, phenylbenzoate, azophenyl and the like, and a photoreactive group bonded to a distal end portion thereof and being capable of undergoing a crosslinking reaction and an isomerization reaction by light induction; has a main chain and a side chain bonded thereto, the side chain having a benzoate group which also serves as a mesogenic component and undergoes a photo-Fries rearrangement reaction.

More specific examples of the structure of the side chain type polymer having a photoreactive group that can exhibit liquid crystallinity are preferably a structure having a main chain composed of at least one kind selected from the group consisting of a radical polymerizable group such as hydrocarbon, (meth) acrylate, itaconate, fumarate, maleate, α -methylene- γ -butyrolactone, styrene, vinyl, maleimide, norbornene, and siloxane, and a side chain formed of at least one kind of the following formulas (1) to (6).

Wherein, A, B, D eachIndependently represent a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;

s is C1-C12 alkylene, and hydrogen atoms bonded to the S are optionally substituted by halogen groups;

t is a single bond or an alkylene group having 1 to 12 carbon atoms, and a hydrogen atom bonded thereto is optionally substituted with a halogen group;

Y₁a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 rings, which are the same or different, selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded thereto are each independently optionally substituted by-COOR₀(in the formula, R₀Hydrogen atom or C1-5 alkyl group), -NO₂、-CN、-CH＝C(CN)₂-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

Y₂is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a C5-C8 alicyclic hydrocarbon, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO₂、-CN、-CH＝C(CN)₂-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y₁The same definition;

x represents a single bond, -COO-, -OCO-, -N-, -CH-, -C.ident.C-, -CH-CO-O-, or-O-CO-CH-, and when the number of X is 2, X is optionally the same or different from each other;

cou represents coumarin-6-yl or coumarin-7-yl, the hydrogen atoms bonded to them each independently being optionally substituted by-NO₂、-CN、-CH＝C(CN)₂-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

one of q1 and q2 is 1 and the other is 0;

q3 is 0 or 1;

p and Q are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a C5-8 alicyclic hydrocarbon, and combinations thereof; wherein, when X is-CH-CO-O-, -O-CO-CH-, P or Q on the side to which-CH-is bonded is an aromatic ring, P is optionally the same as or different from each other when the number of P is 2 or more, and Q is optionally the same as or different from each other when the number of Q is 2 or more;

l1 is 0 or 1;

l2 is an integer of 0 to 2;

when l1 and l2 are both 0, A represents a single bond when T is a single bond;

when l1 is 1, B represents a single bond when T is a single bond;

h and I are each independently a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, and combinations thereof.

The side chain is preferably selected from the group consisting of the following formulas (7) to (10).

In the formula, A, B, D, Y₁、X、Y₂And R has the same definition as above;

l represents an integer of 1 to 12;

m represents an integer of 0 to 2, m1 and m2 represent an integer of 1 to 3;

n represents an integer of 0 to 12 (wherein, when n is 0, B is a single bond).

The side chain is preferably selected from the group consisting of the following formulas (11) to (13).

Wherein A, X, l, m2 and R have the same meanings as defined above.

The side chain is preferably a side chain represented by the following formula (14) or (15).

In the formula, A, Y₁X, l, m1 and m2 have the same definitions as above.

The side chain is preferably a side chain represented by the following formula (16) or (17).

Wherein A, X, l and m have the same meanings as defined above.

Side chain type polymer having liquid crystalline side chain

(A) The side chain type polymer may have a side chain other than the side chain having the photoreactive group. For example, the side chain polymer (a) may have any 1 liquid crystalline side chain selected from the group consisting of the following formulas (21) to (31).

Wherein A, B, q1 and q2 have the same meanings as defined above;

Y₃is a group selected from the group consisting of monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, nitrogen-containing heterocycle, C5-8 alicyclic hydrocarbon and a combination thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO₂CN, -a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms;

R₃represents a hydrogen atom, -NO₂、-CN、-CH＝C(CN)₂-CH ═ CH — CN, a halogen group, a monovalent benzene ring, naphthalene ring, biphenyl ring, furan ring, nitrogen-containing heterocycle, alicyclic hydrocarbon having 5 to 8 carbon atoms, alkyl having 1 to 12 carbon atoms, or alkoxy having 1 to 12 carbon atoms;

l represents an integer of 1 to 12, m represents an integer of 0 to 2, wherein in the formulae (25) to (26), the total sum of all m is 2 or more, in the formulae (27) to (28), the total sum of all m is 1 or more, and m1, m2 and m3 each independently represents an integer of 1 to 3;

R₂represents a hydrogen atom, -NO₂-CN, halogen radical, aBenzene ring, naphthalene ring, biphenyl ring, furan ring, nitrogen-containing heterocycle, alicyclic hydrocarbon with 5-8 carbon atoms, alkyl or alkoxy;

Z₁、Z₂represents a single bond, -CO-, -CH₂O-、-CH＝N-、-CF₂-。

Production of side chain type polymer

The side chain type polymer can be obtained as follows: the photoreactive side chain monomer having the side chain having the photoreactive group may be polymerized, or the photoreactive side chain monomer may be polymerized with another monomer, for example, a liquid crystalline side chain monomer.

[ photoreactive side chain monomer ]

The photoreactive side chain monomer is a monomer capable of forming a polymer having a side chain having a photoreactive group at a side chain site of the polymer when the polymer is formed.

As the photoreactive group contained in the side chain, the following structures and derivatives thereof are preferable.

More specific examples of the photoreactive side chain monomer are preferably a structure having a polymerizable group composed of at least one member selected from the group consisting of a radical polymerizable group such as hydrocarbon, (meth) acrylate, itaconate, fumarate, maleate, α -methylene- γ -butyrolactone, styrene, vinyl, maleimide, norbornene and the like, and a siloxane, and a side chain formed of at least one of the above formulae (1) to (6), preferably, for example, a side chain formed of at least one of the above formulae (7) to (10), a side chain formed of at least one of the above formulae (11) to (13), a side chain represented by the above formula (14) or (15), and a side chain represented by the above formula (16) or (17).

[ liquid Crystal side chain monomer ]

The liquid crystalline side chain monomer is a monomer in which a polymer derived from the monomer exhibits liquid crystallinity and the polymer can form a mesogenic group at a side chain position.

The mesogenic group in the side chain may be a group having a single mesogenic structure such as biphenyl or phenyl benzoate, or may be a group having a mesogenic structure in which side chains are hydrogen-bonded to each other such as benzoic acid. As the mesogenic group having a side chain, the following structure is preferable.

More specific examples of the liquid crystalline side chain monomer preferably have a structure having a polymerizable group composed of at least one member selected from the group consisting of a radical polymerizable group such as hydrocarbon, (meth) acrylate, itaconate, fumarate, maleate, α -methylene- γ -butyrolactone, styrene, vinyl, maleimide, norbornene and siloxane, and a side chain formed of at least one member selected from the group consisting of the above formulae (21) to (31).

In the present application, examples of the photoreactive and/or liquid crystalline side chain monomer include compounds represented by the following formulae (a01) to (a20), but are not limited thereto.

Wherein R represents a hydrogen atom or a methyl group; s represents an alkylene group having 2 to 10 carbon atoms; r¹⁰Represents Br or CN; s represents an alkylene group having 2 to 10 carbon atoms; u represents 0 or 1; and Py represents 2-pyridyl, 3-pyridyl or 4-pyridyl. In addition, v represents 1 or 2.

(A) The side chain type polymer can be obtained by polymerization of a photoreactive side chain monomer having a side chain having a photoreactive group as described above. The side chain monomer is obtained by copolymerization of a photoreactive side chain monomer that does not exhibit liquid crystallinity and a liquid crystalline side chain monomer, or copolymerization of a photoreactive side chain monomer that exhibits liquid crystallinity and a liquid crystalline side chain monomer.

It may be copolymerized with other monomers within a range not impairing the capability of exhibiting liquid crystallinity.

Examples of the other monomers include industrially available monomers capable of radical polymerization.

Specific examples of the other monomer include unsaturated carboxylic acids, acrylate compounds, methacrylate compounds, maleimide compounds, acrylonitrile, maleic anhydride, styrene compounds, vinyl compounds, and the like.

Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

Examples of the acrylate compound include those described in [0152] of WO 2014/054785.

Examples of the methacrylate ester compound include those described in [0153] of WO 2014/054785.

Examples of the vinyl compound, styrene compound and maleimide compound include those described in [0154] of WO 2014/054785.

The method for producing the side chain polymer of the present embodiment is not particularly limited, and a general method for industrial treatment may be used. Specifically, the polymer can be produced by cationic polymerization, radical polymerization, or anionic polymerization of a liquid crystalline side chain monomer or a photoreactive side chain monomer using a vinyl group. Among them, radical polymerization is particularly preferable from the viewpoint of ease of reaction control and the like.

As the polymerization initiator for radical polymerization, known compounds such as radical polymerization initiators and reversible addition-fragmentation chain transfer (RAFT) polymerization reagents can be used.

The radical thermal polymerization initiator is a compound that generates radicals by heating to a decomposition temperature or higher. Examples of such a radical thermal polymerization initiator include those described in [0157] of WO2014/054785 publication. Such radical thermal polymerization initiators may be used in 1 kind alone, or may be used in combination of 2 or more kinds.

The radical photopolymerization initiator is not particularly limited as long as it is a compound that initiates radical polymerization by irradiation with light. Examples of such a radical photopolymerization initiator include those described in [0158] of WO2014/054785 publication. These compounds may be used alone, or 2 or more of them may be used in combination.

The radical polymerization method is not particularly limited, and emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, bulk polymerization, solution polymerization, and the like can be used.

The organic solvent used in the polymerization reaction for obtaining the side chain type polymer is not particularly limited as long as the polymer formed is dissolved. Specific examples thereof include those described in [0161] of WO 2014/054785.

These organic solvents may be used alone or in combination. Further, the solvent that does not dissolve the produced polymer may be mixed with the organic solvent and used as long as the produced polymer is not precipitated.

In addition, in radical polymerization, oxygen in an organic solvent may cause inhibition of the polymerization reaction, and therefore, it is preferable to use the organic solvent after degassing as much as possible.

The polymerization temperature in the radical polymerization can be selected from any temperature of 30 to 150 ℃, and preferably from 50 to 100 ℃. The reaction may be carried out at any concentration, but when the concentration is too low, it is difficult to obtain a polymer having a high molecular weight, and when the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring becomes difficult, and therefore the monomer concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction may be carried out at a high concentration in the initial stage of the reaction, and an organic solvent may be added thereafter.

In the radical polymerization reaction, when the ratio of the radical polymerization initiator to the monomer is large, the molecular weight of the resulting polymer becomes small, and when the ratio of the radical polymerization initiator to the monomer is small, the molecular weight of the resulting polymer becomes large, and therefore the ratio of the radical polymerization initiator to the monomer to be polymerized is preferably 0.1 to 10 mol%. In addition, various monomer components, solvents, initiators, and the like may be added during the polymerization.

[ recovery of Polymer ]

When the polymer to be produced is recovered from the reaction solution of the side chain type polymer obtained by the above reaction, the reaction solution may be charged into a poor solvent to precipitate the polymer. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, heptane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, and water. The polymer precipitated by being put into the poor solvent may be recovered by filtration and then dried at normal temperature or under reduced pressure or dried by heating. Further, when the operation of re-dissolving the polymer recovered by precipitation in the organic solvent and re-precipitating and recovering is repeated 2 to 10 times, impurities in the polymer can be reduced. Examples of the poor solvent in this case include alcohols, ketones, hydrocarbons and the like, and when 3 or more kinds of poor solvents selected from these are used, the purification efficiency is further improved, which is preferable.

The molecular weight of the side chain type polymer (A) of the present invention is preferably 2000 to 1000000, more preferably 5000 to 200000, in terms of the strength of the obtained coating film, the workability in forming the coating film, and the uniformity of the coating film, as measured by GPC (Gel Permeation Chromatography).

[ preparation of composition ]

The composition used in the present invention is preferably prepared as a coating liquid in a manner suitable for forming a liquid crystal alignment film. That is, the composition used in the present invention is preferably prepared as a solution in which a resin component for forming a resin coating is dissolved in an organic solvent. Here, the resin component refers to the resin component containing the side chain type polymer described above. In this case, the content of the resin component is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass.

In the composition of the present embodiment, the resin component may be all the side chain type polymers described above, or other polymers than these may be mixed in a range not impairing the liquid crystal display ability and the photosensitive property. In this case, the content of the other polymer in the resin component is 0.5 to 80% by mass, preferably 1 to 50% by mass.

Examples of such other polymers include polymers other than the side chain type polymers described above, which are formed from poly (meth) acrylates, polyamic acids, polyimides, polyamic acid esters, polyureas, polyamic acid-polyureas obtained by polymerizing a diisocyanate compound with a tetracarboxylic acid derivative or a diamine compound, polyimide-polyureas obtained by further imidization, and the like.

< (B) organic solvent

The organic solvent used in the composition of the present invention is not particularly limited as long as it is an organic solvent capable of dissolving the resin component. Specific examples thereof are listed below.

Examples thereof include: n, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylsulfoxide, γ -butyrolactone, 3-methoxy-N, N-dimethylpropionamide, 3-ethoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, 1, 3-dimethylimidazolidinone, ethylpentyl ketone, methylnonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diethylene glycol dimethyl ether, propylene glycol dimethyl pyrrolidone, propylene glycol dimethyl ether, propylene glycol dimethyl pyrrolidone, propylene glycol dimethyl ether, propylene glycol dimethyl sulfoxide, and propylene glycol dimethyl sulfoxide, 4-hydroxy-4-methyl-2-pentanone, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol t-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, and the like. They may be used alone or in combination.

Additive (C)

The composition of the present application has an additive (C) characterized in that the lowest triplet energy is lower than that of a compound derived from a photoreactive group on a side chain of a side chain type polymer.

By using the additive (C) having the above-described characteristics, that is, the additive (C) having a specific minimum triplet energy, the light irradiation dose range can be widened and the production efficiency of the liquid crystal alignment film can be improved in the photo-alignment method used for the alignment treatment of the liquid crystal alignment film obtained from the composition.

Here, the triplet energy is energy possessed by a molecule which is excited by light energy and becomes a triplet state. In particular, the energy difference between the lowest excited triplet state (T1) and the molecule in the ground state is referred to as the lowest triplet energy.

In addition, the triplet state is a state in which 2 orbitals each have 1 unpaired electron when the molecule is excited by the energy of light, and in this case, a state in which the spin directions of 2 unpaired electrons are the same is referred to as a triplet state, and a state in which the spin directions of 2 electrons are opposite is referred to as a singlet state. Generally, the triplet state has lower energy than the corresponding singlet state, but the excited triplet state has a long lifetime, and therefore, the reaction has many opportunities, and a distinctive photoreaction is often generated based on the excited triplet state.

Generally, the lifetime of a high excited state other than the lowest excited state (S1 if the state is a single-state and T1 if the state is a triplet state) is short, and rapidly decreases to S1 and T1. Therefore, even when light having a short wavelength and high energy is used, excitation is S2 or S3, and light emission and reaction often occur at S1 or T1 which are the lowest excited states.

The lowest triplet energy can be determined as follows.

As a prerequisite for the measurement, a molecule in an excited triplet state sometimes selects a radiative transfer process of emitting phosphorescence and returning to a ground singlet state, in addition to various photoreactions. Here, if phosphorescence emitted from the lowest triplet excited state is measured by a spectrophotometer or the like, the lowest triplet energy can be estimated.

That is, the lowest triplet energy can be calculated from the measured phosphorescence spectrum. The phosphorescence spectrum can be measured using a commercially available spectrophotometer.

The general method for measuring phosphorescence spectrum includes: a method of measuring a target compound by dissolving the compound in a solvent and irradiating the solution with excitation light at a low temperature (see, for example, the 4 th edition of the laboratory chemistry lecture 7p384-398(1992) compiled by the Japan chemical society); or a method in which a thin film is formed by vapor deposition of a target compound on a silicon substrate, and the phosphorescence spectrum is measured by irradiation with excitation light at a low temperature (see, for example, japanese patent application laid-open No. 2007-022986).

The excited triplet level can be calculated as follows: the wavelength of the 1 st peak on the short wavelength side or the wavelength at the position where the short wavelength side rises in the phosphorescence spectrum is read and converted into an energy value per 1 mole of light according to the following formula, and can be calculated. In the following numerical formula (E1), N_AThe value representing the Avogastrol constant, E the lowest triplet energy, and h the Planckian constant (6.63X 10)^-34Js), c represents the speed of light (3.00X 10)⁸m/s), λ represents the wavelength (nm) at which the short-wavelength side of the phosphorescence spectrum rises.

E(kJ/mol)＝N_A×(hc/λ) (E1)

For example, the side chain of the side chain type polymer (A) has the following formula (A-1) (wherein Y is₂And R has the same definition as above. When the group represented by formula (A-1) is a part of a side chain type polymer, and is bonded thereto), the compound derived from a photoreactive group is represented by formula (A-2) (wherein Y is₂And R has the same definition as above), and (C) the lowest triplet energy of the additive is preferably lower than that of the compound represented by the formula (A-2).

The side chain of the side chain polymer (A) has the following formula (A-3) (wherein Y is₁Have the same definitions as above. When the group represented by formula (A-3) is a part of a side chain type polymer, and is bonded thereto), the compound derived from a photoreactive group is represented by formula (A-4) (wherein Y is₁Having the same definition as above), the lowest triplet energy of the (C) additive is preferably lower than that of the compound represented by the formula (a-4).

For example, the case where the group represented by the formula (A-1) is a group represented by the following formula (A-1-1) and the compound represented by the formula (A-2) is a compound represented by the following formula (A-2-1);

examples of the group represented by the formula (A-1) include, but are not limited to, a group represented by the following formula (A-1-2), and a compound represented by the formula (A-2) includes a compound represented by the following formula (A-2-2). It is to be noted that the same definitions as above are given.

Examples of the compound include, but are not limited to, a compound represented by the following formula (A-3-1) as the group represented by the formula (A-3) and a compound represented by the following formula (A-4-1) as the compound represented by the formula (A-4). It is to be noted that the same definitions as above are given.

In this case, the additive (C) includes compounds represented by the following formulas (C-1) to (C-27), but is not limited thereto.

In the present invention, it is considered that the additive (C) functions as a matting agent. Hereinafter, as an example, a case where the side chain type polymer (A) has a group represented by the formula (A-1) or (A-3) as a photoreactive group, specifically, a case where it has a cinnamic acid group is considered.

When the additive (C) is not added, the side chain polymer (a) is irradiated with light for alignment control, and the cinnamic acid group, which is a photoreactive group in the side chain polymer (a), is excited, and the side chain polymer (a) reacts sensitively to the light.

On the other hand, when an additive having an excited triplet energy lower than that of cinnamic acid is introduced, the energy of the excited state in the cinnamic acid group in the side chain polymer (a) is transferred to the additive functioning as a matting agent, and thus deactivated to be delusted. Therefore, the photoreactivity of the side chain type polymer (a) having a cinnamic acid group as a photoreactive group is lowered, and the sensitivity to the irradiation light or the irradiation amount is lowered, so that the irradiation amount range in which the alignment controllability is stably generated can be widened.

The above-described effect is not limited to the side chain type polymer (a) having a cinnamic acid group, and is similarly generated in the side chain type polymer (a) having another photoreactive group, for example, a photoreactive group such as a chalcone skeleton, a coumarin skeleton, a stilbene skeleton, or an azobenzene skeleton.

Hereinafter, a photoreactive group other than the photoreactive group including a cinnamic acid group will be described.

(C) The additive may be present in the composition in 1 or more than 2 types.

In this case, the content of the additive (C) in the composition may be 0.01 to 200 parts by mass, preferably 0.05 to 100 parts by mass, based on 100 parts by mass of the resin component contained in the composition.

In addition, as the additive (C), if the additive (C) to be used is a liquid, it can be used as the organic solvent (B). At this time, most of the coating film is evaporated and disappears when the coating film is obtained by heating in an oven or the like. When the additive (C) is used as the organic solvent (B) in consideration of the vanished portion, the content of the additive (C) may be 2 to 80% by mass, preferably 5 to 50% by mass of the entire organic solvent (B).

The composition used in the present invention may contain other components in addition to the side chain polymer (a), the organic solvent (B), and the additive (C). Examples thereof include, but are not limited to, solvents and compounds for improving film thickness uniformity and surface smoothness when the composition is applied, and compounds for improving adhesion between a liquid crystal alignment film and a substrate.

Specific examples of the solvent (poor solvent) for improving the uniformity of the film thickness and the surface smoothness include those described in [0171] of WO 2014/054785.

These poor solvents may be used in 1 kind, or may be used in combination of two or more kinds. When the solvent as described above is used, the solvent is preferably 5 to 80% by mass, more preferably 20 to 60% by mass of the entire solvent so as not to significantly reduce the solubility of the entire solvent contained in the composition.

Examples of the compound for improving the film thickness uniformity and surface smoothness include a fluorine-based surfactant, a silicone-based surfactant, and a nonionic surfactant.

More specifically, examples thereof include Eftop (registered trademark) 301, EF303, EF352 (manufactured by Tohkem products Corporation), Megafac (registered trademark) F171, F173, R-30 (manufactured by DIC CORPORATION), Fluorad FC430, FC431 (manufactured by Sumitomo 3M Limited), Asahiguard (registered trademark) AG710 (manufactured by Asahi Nitro Corporation), Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, and SC106(AGC SEIMI CHEMICAL CO., LTD.). The proportion of the surfactant to be used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of the resin component contained in the composition.

Specific examples of the compound for improving the adhesion between the liquid crystal alignment film and the substrate include functional silane-containing compounds described in [0174] of WO 2014/054785.

Further, in order to improve the adhesion between the substrate and the liquid crystal alignment film and to prevent the deterioration of electrical characteristics due to a backlight when the liquid crystal display element is formed, the following additives of a phenolplast type and an epoxy group-containing compound may be contained in the composition. Specific examples of the phenolic plastic additive are shown below, but the additive is not limited to this structure.

Specific examples of the epoxy group-containing compound include those described in [0177] of WO 2014/054785.

When a compound for improving adhesion to a substrate is used, the amount thereof is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of the resin component contained in the composition. When the amount is less than 0.1 part by mass, the effect of improving the adhesion cannot be expected, and when it is more than 30 parts by mass, the alignment property of the liquid crystal may be deteriorated.

In the composition of the present application, in addition to the above-mentioned substances, a dielectric substance or a conductive substance may be added for the purpose of changing electrical characteristics such as dielectric constant and conductivity of the liquid crystal alignment film, and a crosslinkable compound may be added for the purpose of improving hardness and density of the film when the liquid crystal alignment film is formed, within a range not to impair the effects of the present invention.

< liquid crystal alignment film using the composition and method for producing the same, < method for producing substrate having liquid crystal alignment film > and method for producing liquid crystal display element >

The liquid crystal alignment film using the composition can be obtained by a photo-alignment method based on polarized light irradiation of a coating film obtained using the composition, as in WO2014/054785 (the entire contents of which are incorporated herein by reference).

Specifically, a substrate having a liquid crystal alignment film, which can be provided with an alignment control capability, particularly a liquid crystal alignment film for a transverse electric field driven liquid crystal display element, can be obtained by the following steps:

[I] a step of coating the composition on a substrate having a conductive film, particularly a conductive film for driving a transverse electric field, to form a coating film;

[ II ] irradiating the coating film obtained in [ I ] with polarized ultraviolet light; and

and [ III ] a step of heating the coating film obtained in [ II ].

In addition to the substrate (1 st substrate) obtained above, a2 nd substrate was prepared to obtain a liquid crystal display element, particularly a transverse electric field drive type liquid crystal display element.

The 2 nd substrate is a substrate having a conductive film, particularly a conductive film for driving a transverse electric field, as in the 1 st substrate, and the 2 nd substrate having a liquid crystal alignment film to which an alignment controllability is imparted can be obtained by the above-described steps [ I ] to [ III ].

In addition to the above-described steps [ I ] to [ III ] (since a substrate having no conductive film is used, the steps [ I '] to [ III' ] may be abbreviated in the present application for convenience sake) as the second substrate 2 instead of the substrate having a conductive film, particularly a conductive film for driving a transverse electric field, the second substrate 2 having a liquid crystal alignment film to which an alignment control capability is added can be obtained.

A method for manufacturing a liquid crystal display element, particularly a transverse electric field drive type liquid crystal display element, comprises the steps of:

[ IV ] the step of obtaining a liquid crystal display element by disposing the 1 st and 2 nd substrates obtained in the above manner to face each other with the liquid crystal interposed therebetween so that the liquid crystal alignment films of the 1 st and 2 nd substrates face each other.

This makes it possible to obtain a liquid crystal display element, particularly a transverse electric field-driven liquid crystal display element.

The respective steps of [ I ] to [ III ] and [ IV ] of the production method of the present invention will be described below.

< Process [ I ] >

In the step [ I ], the composition is applied to a substrate having a conductive film, particularly a conductive film for driving a transverse electric field, to form a coating film.

< substrate >

The substrate is not particularly limited, and when the liquid crystal display element to be manufactured is transmissive, a substrate having high transparency is preferably used. In this case, there is no particular limitation, and a glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, or the like can be used.

In addition, in consideration of application to a reflective liquid crystal display element, an opaque substrate such as a silicon wafer may be used.

< conductive film >

The substrate has a conductive film, particularly a conductive film for driving a transverse electric field.

When the conductive film is a liquid crystal display element of a transmissive type, examples thereof include, but are not limited to, ITO (Indium Tin Oxide) and IZO (Indium Zinc Oxide).

In the case of a reflective liquid crystal display element, examples of the conductive film include, but are not limited to, materials that reflect light, such as aluminum.

As a method for forming a conductive film on a substrate, a conventionally known method can be used.

A method for applying the above composition to a substrate having a conductive film is not particularly limited.

As for the coating method, a method using screen printing, offset printing, flexographic printing, inkjet method, or the like is generally industrially used. As other coating methods, there are a dipping method, a roll coating method, a slit coating method, a spin coating method (spin coating method), a spray coating method, and the like, and they can be used according to the purpose.

After coating the composition on a substrate having a conductive film, the solvent is evaporated at 50 to 200 ℃, preferably 50 to 150 ℃ by a heating means such as a hot plate, a thermal cycle oven or an IR (infrared) oven, thereby obtaining a coating film. The drying temperature in this case is preferably lower than the liquid crystal phase appearance temperature of the side chain type polymer.

When the thickness of the coating film is too large, it is disadvantageous in terms of power consumption of the liquid crystal display element, and when the thickness of the coating film is too small, reliability of the liquid crystal display element may be lowered, and therefore, it is preferably 5nm to 300nm, more preferably 10nm to 150 nm.

After the step [ I ] and before the next step [ II ], a step of cooling the substrate having the coating film formed thereon to room temperature may be provided.

< Process [ II ] >

In the step [ II ], the coating film obtained in the step [ I ] is irradiated with polarized ultraviolet rays. When the film surface of the coating film is irradiated with polarized ultraviolet light, the substrate is irradiated with polarized ultraviolet light from a specific direction through a polarizing plate. As the ultraviolet ray to be used, ultraviolet rays having a wavelength in the range of 100nm to 400nm can be used. Preferably, the optimum wavelength is selected by means of a filter or the like according to the kind of the coating film to be used. Further, for example, ultraviolet rays having a wavelength in the range of 290 to 400nm can be selectively used so that the photocrosslinking reaction can be selectively induced. As the ultraviolet rays, light emitted from a high-pressure mercury lamp, for example, can be used.

The irradiation amount of the polarized ultraviolet rays depends on the coating film to be used. The irradiation amount is preferably in the range of 1% to 70%, more preferably in the range of 1% to 50%, of the amount of polarized ultraviolet light that achieves the maximum value of Δ a (hereinafter also referred to as Δ Amax), which is the difference between the ultraviolet absorbance of the coating film in the direction parallel to the polarization direction of the polarized ultraviolet light and the ultraviolet absorbance of the coating film in the direction perpendicular to the polarization direction of the polarized ultraviolet light.

< Process [ III ] >

In the step [ III ], the coating film irradiated with the polarized ultraviolet ray in the step [ II ] is heated. The orientation control ability can be imparted to the coating film by heating.

Heating means such as a hot plate, a thermal cycle type oven, or an IR (infrared ray) type oven can be used for heating. The heating temperature may be determined in consideration of the temperature at which the coating film used exhibits liquid crystallinity.

The heating temperature is preferably within a temperature range at which the side chain polymer exhibits liquid crystallinity (hereinafter referred to as "liquid crystallinity expression temperature"). In the case of a film surface such as a coating film, it is expected that the liquid crystallinity expression temperature of the coating film surface is lower than the liquid crystallinity expression temperature when a side chain polymer exhibiting photosensitivity of liquid crystallinity is observed as a whole. Therefore, the heating temperature is more preferably within the temperature range of the liquid-crystalline expression temperature of the coating film surface. That is, the temperature range of the heating temperature after the irradiation of the polarized ultraviolet ray is preferably: a temperature in a range having a temperature lower by 10 ℃ than the lower limit of the temperature range of the liquid crystal property expression temperature of the side chain polymer to be used as the lower limit and a temperature lower by 10 ℃ than the upper limit of the liquid crystal temperature range as the upper limit. When the heating temperature is lower than the above temperature range, the effect of increasing anisotropy by heat tends to be insufficient in the coating film, and when the heating temperature is too high as compared with the above temperature range, the state of the coating film tends to be close to an isotropic liquid state (isotropic phase), and in this case, it may be difficult to perform reorientation in one direction by self-assembly (self-assembly).

The liquid crystal property expression temperature is a temperature not lower than the glass transition temperature (Tg) at which the surface of the side chain polymer or the coating film undergoes a phase transition from a solid phase to a liquid crystal phase, and not higher than the Isotropic phase transition temperature (Tiso) at which the surface undergoes a phase transition from a liquid crystal phase to a homogeneous phase (Isotropic phase).

By having the above steps, the production method of the present invention can efficiently introduce anisotropy into a coating film. Further, a substrate with a liquid crystal alignment film can be efficiently produced.

< Process [ IV ] >

The step IV is a step of preparing a lateral electric field drive type liquid crystal display element by disposing a substrate (first substrate) having a liquid crystal alignment film on a conductive film obtained in the step III and a substrate (second substrate) having a liquid crystal alignment film without a conductive film obtained in the same manner as in the steps I 'to III' so as to face each other with the liquid crystal alignment films of both substrates facing each other through a liquid crystal, and preparing a liquid crystal cell by a known method. The steps [ I '] to [ III' ] can be performed in the same manner as the steps [ I ] to [ III ], except that in the step [ I ], a substrate having no conductive film is used instead of the substrate having the conductive film. The steps [ I ] to [ III ] are different from the steps [ I '] to [ III' ] only in the presence or absence of the conductive film, and therefore, the steps [ I '] to [ III' ] are omitted from description.

When an example of manufacturing a liquid crystal cell or a liquid crystal display element is described, the following method can be exemplified: a method of preparing the first substrate and the second substrate, spreading spacers on the liquid crystal alignment film of one substrate, attaching the other substrate with the liquid crystal alignment film surface facing the inside, injecting liquid crystal under reduced pressure, and sealing; or a method of dropping liquid crystal onto the liquid crystal alignment film surface on which the spacers are dispersed, and then attaching and sealing the substrate. In this case, it is preferable that the one-side substrate is a substrate having an electrode having a structure like comb teeth for driving a transverse electric field. The diameter of the spacer in this case is preferably 1 to 30 μm, more preferably 2 to 10 μm. The diameter of the spacer determines the distance between a pair of substrates sandwiching the liquid crystal layer, i.e., the thickness of the liquid crystal layer.

The method for producing a substrate with a coating film of the present invention forms a coating film by applying the composition to a substrate and then irradiates polarized ultraviolet rays. Then, by heating, the substrate with the liquid crystal alignment film having liquid crystal alignment controllability is manufactured by efficiently introducing anisotropy into the side chain type polymer film.

The coating film used in the present invention utilizes the principle of molecular reorientation induced by photoreaction of side chains and self-assembly based on liquid crystallinity, and realizes high efficiency in introducing anisotropy into the coating film. In the production method of the present invention, when the side chain type polymer has a structure in which a photocrosslinkable group is a photoreactive group, a liquid crystal display element is produced by forming a coating film on a substrate using the side chain type polymer, irradiating the coating film with polarized ultraviolet rays, and then heating the coating film.

The photoalignment method of a side chain type polymer using a structure having a photoreactive group such as a photocrosslinkable group, a group subjected to a photo-fries rearrangement, or an isomerized group is described in detail in WO2014/054785 (the entire contents of this document are incorporated herein by reference), and the same applies to this application.

As described above, the substrate for a liquid crystal display element, particularly the substrate for a transverse electric field driven liquid crystal display element, or the liquid crystal display element having the substrate, particularly the transverse electric field driven liquid crystal display element, manufactured by the composition of the present invention or the method of the present invention is excellent in reliability.

Further, since the range of the irradiation amount (so-called "irradiation amount margin") in which the alignment controllability of the liquid crystal alignment film is stably obtained can be widened by the composition of the present invention or the method of the present invention, even if the time of irradiation with polarized light or the like is slightly deviated from the control value in the production process of the liquid crystal alignment film, the liquid crystal alignment film with unchanged quality can be obtained, and the production efficiency of the liquid crystal alignment film can be improved. Therefore, the substrate for a liquid crystal display element, particularly the substrate for a transverse electric field driven liquid crystal display element, or the liquid crystal display element having the substrate, particularly the transverse electric field driven liquid crystal display element, manufactured by the composition of the present invention or the method of the present invention can be suitably used for a large-screen and high-definition liquid crystal television or the like.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Examples

The abbreviations for the (meth) acrylate compounds and additives used in the examples and their structures are shown below.

(meth) acrylate Compound

MA-1 was synthesized by a synthesis method described in patent document (WO 2011-084546).

MA-2 was synthesized by a synthesis method described in patent literature (Japanese patent application laid-open No. 9-118717).

< additive >

Commercially available products (manufactured by Tokyo chemical industry Co., Ltd.) were used as T-1 to T-8.

T-1: benzanthrone

T-2: acridine

T-3: pyrene

T-4: 9-fluorenones

T-5: benzil radical

T-6: 2-Naphthoacetophenones

T-7: 1, 10-phenanthroline

T-8: 2-methylbenzophenone

The organic solvents used in examples and the like are abbreviated as follows.

NEP: n-ethyl-2-pyrrolidone

PB: propylene glycol monobutyl ether

THF: tetrahydrofuran (THF)

Polymerization example 1

MA-1(13.3g, 40.0mmol) and MA-2(18.4g, 60.0mmol) were dissolved in THF (182.3g), degassed with a diaphragm pump, and then 2, 2' -azobisisobutyronitrile (0.82g, 5.0mmol) was added and degassed again. Thereafter, the reaction was carried out at 50 ℃ for 30 hours to obtain a polymer solution of methacrylic acid ester.

The polymer solution was added dropwise to diethyl ether (1500ml), and the resulting precipitate was filtered. The precipitate was washed with diethyl ether and dried in an oven at 40 ℃ under reduced pressure to obtain a methacrylate polymer powder.

NEP (127g) was added to 10.0g of the obtained powder, and the mixture was stirred at room temperature for 16 hours to dissolve it. PB (113g) was added to the solution and stirred to obtain a methacrylate polymer solution PMA-1.

(example 1)

To the methacrylate polymer solution PMA-1(5.00g) obtained above was added the additive T-1(0.010g), and the mixture was stirred at room temperature for 1 hour to obtain a liquid crystal aligning agent A-1.

(examples 2 to 5 and comparative examples 1 to 4)

Liquid crystal aligning agents A-2 to A-5 of examples 2 to 5 were obtained in the same manner as in example 1, except for using the compositions shown in Table 1.

In addition, in comparative examples 1 to 4, liquid crystal aligning agents B-1 to B-4 were prepared in the same manner.

[ Table 1]

TABLE 1 compositions of liquid crystal aligning agents A-1 to A-5 of examples 1 to 5 and liquid crystal aligning agents B-1 to B-4 of comparative examples 1 to 4

< production of substrate for measuring photoreactivity >

Using the liquid crystal aligning agent A-1 obtained above, a substrate for measuring photoreactivity was produced in the following procedure. A quartz substrate having a size of 40mm × 40mm and a thickness of 1.0mm was used as the substrate.

The liquid crystal aligning agent A-1 obtained in example 1 was filtered through a filter having a filter pore size of 1.0 μm, spin-coated on a quartz substrate, and dried on a hot plate at 70 ℃ for 90 seconds to form a liquid crystal alignment film having a film thickness of 100 nm. Then, the coated film was laminated with a polarizing plate so as to be 30mJ/cm²The substrate with the photoreactive liquid crystal alignment film was obtained by irradiating 313nm ultraviolet ray.

Substrates for measuring photoreactivity were also prepared for the liquid crystal aligning agents A-2 to A-5 and B-1 to B-4 obtained in examples 2 to 5 and comparative examples 1 to 4 in the same manner as for the liquid crystal aligning agent A-1.

< determination of photoreaction Rate >

The photoreactivity of the liquid crystal alignment film produced by the above procedure was calculated from the absorbance and the following equation.

In addition, an ultraviolet-visible near-infrared analyzer U-3100PC manufactured by Shimadzu corporation was used for the measurement of absorbance.

Here, a (initial) represents the absorbance before UV irradiation, and a (exposed) represents the absorbance after UV irradiation. In this case, the closer the photoreaction rate is to 0, the less photoreaction occurs.

< production of substrate for In-plane orientation (In-plane order parameter) measurement >

Further, in order to confirm the optical anisotropy of the liquid crystal alignment film, a substrate for in-plane alignment degree measurement was prepared using the liquid crystal aligning agent a-1 obtained above. A quartz substrate having a size of 40mm × 40mm and a thickness of 1.0mm was used as the substrate.

The liquid crystal aligning agent A-1 obtained in example 1 was filtered through a 1.0 μm filter, spin-coated on a quartz substrate, and dried on a hot plate at 70 ℃ for 90 seconds to form a liquid crystal alignment film having a film thickness of 100 nm. Then, the coated film was laminated with a polarizing plate so as to be 30mJ/cm²After irradiation with 313nm ultraviolet light, the substrate was heated on a hot plate at 140 ℃ for 10 minutes to obtain a substrate with a liquid crystal alignment film.

Substrates for in-plane alignment degree measurement were prepared for the liquid crystal aligning agents A-2 to A-5 and B-1 to B-4 obtained in examples 2 to 5 and comparative examples 1 to 4 by the same method as for the liquid crystal aligning agent A-1.

< measurement of degree of in-plane orientation >

Using the substrate with the liquid crystal alignment film prepared in the above, S, which is the in-plane alignment degree, was calculated from the absorbance of polarized light by the following equation in order to measure the optical anisotropy of the liquid crystal alignment film.

Here, A_paraDenotes the absorbance in the direction parallel to the direction of the irradiated polarized UV, A_perDenotes the absorbance in the direction perpendicular to the direction of the irradiated polarized UV. A. the_largeThe absorbance, A, is the absorbance with a larger value when the absorbance in the parallel direction is compared with the absorbance in the perpendicular direction_smallThe absorbance is smaller when the absorbance in the parallel direction is compared with the absorbance in the perpendicular direction. The closer the absolute value of the in-plane orientation degree is to 1, the more the same orientation state is exhibited.

The calculated photoreaction rate and the absolute value of the in-plane orientation S are shown in table 2. The degree of in-plane orientation is expressed by using the following reference.

Very good: s has an absolute value of 0.6 or more

O: the absolute value of S is more than 0.5 and less than 0.6

And (delta): the absolute value of S is more than 0.4 and less than 0.5

[ Table 2]

Table 2.

Photoreaction rate and degree of in-plane orientation when using the liquid crystal orientation agents of examples 1 to 5 and comparative examples 1 to 4

In Table 2, the lowest triplet energy values are described in the chemical new series photochemical (Shanghua House), Handbook of Photochemistry, Third Edition (CRC Press), Photochem photobiol. Sci.,2011,10,1902-1909, and the like.

In addition, the value of the lowest triplet energy value of comparative example 1 represents the lowest triplet energy of cinnamic acid derived from a photoreactive group in the polymer, i.e., a cinnamic acid group.

As shown in Table 2, it was confirmed that the liquid crystal aligning agents of examples 1 to 5 to which the additive of the present invention was added had a lower photoreactivity than the liquid crystal aligning agent of comparative example 1 to which no additive was added.

In addition, it was confirmed that the in-plane orientation degree S of optical anisotropy was increased under the condition that the photoreaction rate was decreased.

Further, it is found that the lower the value of the lowest triplet energy of the additive is, the lower the value is, that is, "240", the lower the photoreaction rate is, and the closer the in-plane orientation degree S is to the desired value, that is, 1.

That is, it was shown that the sensitivity of the photoreactive group was blunted in the presence of the additive of the present invention, and thus it was possible to adjust to an optimum UV irradiation region even under the condition that the ultraviolet irradiation amount was excessive.

Even under the condition of excessive ultraviolet irradiation, the ultraviolet irradiation can be adjusted to the optimum UV irradiation region, so that the treatment boundary in the UV irradiation step is enlarged, and the improvement of the manufacturing yield is expected. Further, the photoreaction rate can be suppressed to an arbitrary ratio by adjusting the kind and introduction amount of the additive. That is, the optimum UV irradiation amount can be finely adjusted to the irradiation amount at which the anisotropy becomes maximum, and a liquid crystal alignment film having higher alignment properties can be obtained.

In examples 1 to 5, the incorporation of an additive having an excited triplet energy lower than that of cinnamic acid is expected to act as a matting agent because of the effect of reducing the photoreactivity of cinnamic acid. That is, it is considered that the photoreaction rate of cinnamic acid decreases through an extinction process in which the energy of the excited state of cinnamic acid is inactivated by the energy transfer to the additive. In addition, there is a tendency that the higher the difference in the lowest triplet energy between the additive and cinnamic acid is, the lower the photoreaction rate is, thus suggesting that the lower the lowest triplet energy of the additive is, the more advantageously the extinction process can be selected.

Therefore, not limited to cinnamic acid, for example, when photoreaction by ultraviolet irradiation is performed in the presence of an additive having the lowest triplet energy lower than those photoreactive groups among a chalcone skeleton, a coumarin skeleton, a stilbene skeleton, and an azobenzene skeleton, for example, since a part of the photoreactive groups also undergoes a quenching process, the photoreactivity is expected to be equal to or lower than that in the absence of the additive. As a result, even in the same liquid crystal aligning agent in which the photoreactive group was not cinnamic acid, as in examples 1 to 5, the photoreactivity could be controlled, and the irradiation dose could be adjusted to the irradiation dose in which the anisotropy became the maximum, which is advantageous to the expansion of the treatment margin in the UV irradiation step.

Claims

1. A composition for producing a liquid crystal alignment film, comprising:

(A) a side chain polymer having a side chain which exhibits liquid crystallinity in a temperature range of 100 to 300 ℃ and has a photoreactive group that undergoes photocrosslinking, photoisomerization or photoFries rearrangement;

(B) an organic solvent; and

(C) an additive agent is added to the mixture,

the lowest triplet energy of the (C) additive is lower than that of the compound derived from the photoreactive group;

the content of the additive (C) in the composition is 0.01 to 200 parts by mass per 100 parts by mass of the resin component contained in the composition.

2. The composition according to claim 1, wherein the side chain type polymer (A) has at least 1 type of side chain having a photoreactive group selected from the group consisting of the following formulas (1) to (6),

wherein A, B, D each independently represents a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;

Y₁a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 rings, which are the same or different, selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded thereto are each independently optionally substituted by-COOR₀、-NO₂、-CN、-CH＝C(CN)₂a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms, wherein R is₀Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;

Y₂is selected from 2-valent benzene ring, naphthalene ring, biphenyl ring, furan ring, pyrrole ring and carbonA number of 5 to 8 alicyclic hydrocarbons and combinations thereof, each hydrogen atom bonded thereto being independently optionally substituted with-NO₂、-CN、-CH＝C(CN)₂-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

one of q1 and q2 is 1 and the other is 0;

q3 is 0 or 1;

l1 is 0 or 1;

l2 is an integer of 0 to 2;

when l1 and l2 are both 0, A represents a single bond when T is a single bond;

when l1 is 1, B represents a single bond when T is a single bond;

3. The composition according to claim 1, wherein the side chain type polymer (A) has at least 1 type of side chain having a photoreactive group selected from the group consisting of the following formulas (7) to (10),

l represents an integer of 1 to 12;

m represents an integer of 0 to 2, m1 and m2 represent an integer of 1 to 3;

n represents an integer of 0 to 12, wherein B is a single bond when n is 0;

r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a group bonded to Y₁The same definition.

4. The composition according to claim 1, wherein the side chain type polymer (A) has at least 1 type of side chain having a photoreactive group selected from the group consisting of the following formulas (11) to (13),

wherein A each independently represents a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;

l represents an integer of 1 to 12, m represents an integer of 0 to 2, and m1 represents an integer of 1 to 3;

r represents a ring selected from among 1-valent benzene rings, naphthalene rings, biphenyl rings, furan rings, pyrrole rings and C5-8 alicyclic hydrocarbons, or a group in which 2 to 6 rings, which are the same or different, selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded thereto are each independently optionally substituted by-COOR₀、-NO₂、-CN、-CH＝C(CN)₂a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms, wherein R is₀Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; or R represents a hydroxyl group or an alkoxy group having 1 to 6 carbon atoms;

b represents a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-.

5. The composition according to claim 1, wherein the side chain type polymer (A) has a side chain having a photoreactive group represented by the following formula (14) or (15),

wherein A each independently represents a single bond, -O-, -CH₂-、-COO-、-OCO-、-CONH-、-NH-CO-, -CH-CO-O-, or-O-CO-CH-;

b represents a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;

l represents an integer of 1 to 12, and m1 and m2 represent an integer of 1 to 3.

6. The composition according to claim 1, wherein the side chain type polymer (A) has a side chain having a photoreactive group represented by the following formula (16) or (17),

wherein A represents a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;

l represents an integer of 1 to 12, and m represents an integer of 0 to 2.

7. The composition according to any one of claims 1 to 6,

wherein the side chain of the side chain type polymer (A) has a group represented by the following formula (A-1),

in the formula, Y₂Is a group selected from the group consisting of a 2-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, a C5-C8 alicyclic hydrocarbon, and combinations thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO₂、-CN、-CH＝C(CN)₂-CH ═ CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

r represents a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, a ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 identical or different rings selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded to these are each independently optionally substituted by-COOR₀、-NO₂、-CN、-CH＝C(CN)₂a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms, wherein R is₀Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;

a group represented by the formula (A-1) is a part of the side chain type polymer (A) and is bonded thereto,

the compound derived from a photoreactive group is a compound represented by the formula (A-2) wherein R, Y₂Have the same definitions as above-mentioned,

the lowest triplet energy of the (C) additive is lower than that of the compound represented by the formula (A-2); or

Wherein the side chain of the side chain type polymer (A) has a group represented by the following formula (A-3),

in the formula, Y₁A ring selected from a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or a group in which 2 to 6 rings, which are the same or different, selected from these substituents are bonded via a linking group B, and hydrogen atoms bonded thereto are each independently optionally substituted by-COOR₀、-NO₂、-CN、-CH＝C(CN)₂a-CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms, wherein R is₀Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;

a group represented by the formula (A-3) is a part of the side chain type polymer (A) and is bonded thereto,

the compound derived from a photoreactive group is a compound represented by the formula (A-4) wherein Y is₁Have the same definitions as above-mentioned,

the lowest triplet energy of the (C) additive is lower than that of the compound represented by the formula (A-4).

8. The composition according to claim 7, wherein the (C) additive is at least 1 selected from the group consisting of compounds represented by the following formulae (C-1) to (C-27),

9. the composition according to claim 1, wherein the side chain polymer (A) has a liquid crystalline side chain selected from any 1 of the following formulae (21) to (31),

wherein A, B each independently represents a single bond, -O-, -CH₂-, -COO-, -OCO-, -CONH-, -NH-CO-, -CH-CO-O-, or-O-CO-CH-;

Y₃is a group selected from the group consisting of 1-valent benzene ring, naphthalene ring, biphenyl ring, furan ring, nitrogen-containing heterocycle, C5-C8 alicyclic hydrocarbon and combination thereof, and hydrogen atoms bonded thereto are each independently optionally substituted by-NO₂CN, -a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

R₃represents a hydrogen atom, -NO₂、-CN、-CH＝C(CN)₂-CH ═ CH — CN, a halogen group, a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a nitrogen-containing heterocycle, an alicyclic hydrocarbon having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms;

one of q1 and q2 is 1 and the other is 0;

l represents an integer of 1 to 12, m represents an integer of 0 to 2, wherein in the formulae (25) to (26), the total of all m is 2 or more, in the formulae (27) to (28), the total of all m3 is 1 or more, and m1, m2 and m3 each independently represents an integer of 1 to 3;

R₂represents a hydrogen atom, -NO₂CN, -a halogen group, a 1-valent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a nitrogen-containing heterocycle, an alicyclic hydrocarbon with 5-8 carbon atoms, and an alkyl group or an alkyloxy group;

Z₁、Z₂represents a single bond, -CO-, -CH₂O-、-CH＝N-、-CF₂-。

10. A method for manufacturing a substrate having a liquid crystal alignment film, wherein the liquid crystal alignment film having an alignment control capability is obtained by the following steps:

[I] a step of applying the composition according to any one of claims 1 to 9 to a substrate having a conductive film to form a coating film;

and [ III ] a step of heating the coating film obtained in [ II ].

11. A substrate having a liquid crystal alignment film, which is produced by the method of claim 10.

12. A liquid crystal display element having the substrate according to claim 11.

13. A method for manufacturing a liquid crystal display element, comprising the steps of:

preparing a 1 st substrate as the substrate according to claim 11;

a step of obtaining a2 nd substrate having a liquid crystal alignment film, which has the following steps of [ I ' ], [ II ' ], and [ III ' ] to obtain the liquid crystal alignment film to which an alignment control capability is imparted; and

[ IV ] a step of obtaining a liquid crystal display element by disposing the 1 st substrate and the 2 nd substrate in opposition to each other with the liquid crystal alignment films of the 1 st substrate and the 2 nd substrate in between,

[ I' ] a step of forming a coating film by applying the composition according to any one of claims 1 to 9 on a2 nd substrate,

[ II '] irradiating the coating film obtained in [ I' ] with polarized ultraviolet ray, and

and [ III '] a step of heating the coating film obtained in [ II' ].

14. A liquid crystal display element produced by the method according to claim 13.