JP6519151B2 - Thermosetting composition having photoalignment, alignment layer, substrate with alignment layer and retardation plate - Google Patents

Description

  The present invention relates to a thermosetting composition having photoalignment properties used for an alignment layer.

  In addition to liquid crystal display elements, various liquid crystal elements such as retardation plates and polarizing plates can be used in various liquid crystals, taking advantage of their orientation and anisotropy of physical properties such as refractive index, dielectric constant and magnetic susceptibility. Applications are being considered.

  An alignment layer is used to align the liquid crystal. As a method of forming an alignment layer, for example, a rubbing method or a photo-alignment method is known, and the photo-alignment method is capable of quantitative control of alignment processing without generating static electricity and dust which are problems of the rubbing method. (See, for example, Patent Document 1).

  The alignment layer is required to have heat resistance, solvent resistance and the like in addition to the liquid crystal alignment ability. For example, the alignment layer may be exposed to heat or a solvent in the manufacturing process of various devices, or may be exposed to high temperatures when using various devices. When the alignment layer is exposed to high temperatures, the liquid crystal alignment ability may be significantly reduced.

  Thus, for example, in Patent Document 2, a liquid crystal aligning agent containing a polymer component having a structure capable of crosslinking reaction by light and a structure crosslinked by heat in order to obtain stable liquid crystal alignment ability, and light There has been proposed a liquid crystal aligning agent containing a polymer component having a structure capable of a crosslinking reaction and a compound having a structure which is crosslinked by heat.

  Patent Document 3 also includes (A) an acrylic copolymer having a photodimerization site and a thermal crosslinking site, in order to obtain excellent liquid crystal alignment ability, sufficient heat resistance, high solvent resistance and high transparency. (B) A heat-curable film-forming composition having photoalignment, which contains a crosslinking agent, has been proposed. The crosslinking agent (B) bonds with the thermal crosslinking site of the (A) acrylic copolymer, and the thermosetting film-forming composition having photoalignment is cured by heating to form a cured film, thereby forming a cured film. Polarized ultraviolet light can be irradiated to form an alignment layer.

  In Patent Document 4, in order to obtain excellent liquid crystal alignment ability, sufficient heat resistance, high solvent resistance and high transparency, (A) an acrylic copolymer having a photodimerization site and a thermal crosslinking site (B ) A photoalignment property containing an acrylic polymer having at least one of a predetermined alkyl ester group and a hydroxyalkyl ester group, and at least one of a carboxyl group and a phenolic hydroxy group, and (C) a crosslinking agent A thermosetting film forming composition having the above has been proposed. (C) A crosslinking agent is a thermally crosslinking film-forming composition having a photoalignment property, which is combined with the thermal crosslinking site of (A) acrylic copolymer and the carboxyl group and phenolic hydroxy group of (B) acrylic polymer. Can be cured by heating to form a cured film, and the cured film can be irradiated with polarized ultraviolet light to form an alignment layer.

  Patent Document 5 describes (A) a compound having a photoalignment group and a hydroxy group, and (B) a hydroxy group in order to obtain excellent liquid crystal alignment ability, sufficient heat resistance, high solvent resistance and high transparency. And a thermosetting resin composition having photoalignment properties, which contains a polymer having at least one of carboxyl groups and a crosslinker (C). The crosslinking agent (C) bonds with the hydroxy group of the compound (A) and the hydroxy group and carboxyl group of the polymer (B), and the thermosetting film forming composition having photoalignment is cured by heating to be a cured film. Can be formed, and the cured film can be irradiated with polarized ultraviolet light to form an alignment layer.

As described above, although it has been proposed that heat curing is performed to improve the heat resistance, solvent resistance, and the like of the alignment layer, photocuring may decrease when heat curing is performed. Among them, as described in Patent Documents 3 to 5, when heat curing is performed by a crosslinking agent, a network structure is formed in the inside of the film, so that the photoreactivity decreases. In particular, when using an acrylic copolymer having a photodimerization site and a thermal crosslinking site as in Patent Documents 3 and 4 and performing heat curing with a crosslinking agent, it is considered that dimerization hardly occurs.
In order to increase the alignment control power of the alignment layer, the irradiation amount of polarized ultraviolet light may be increased and the irradiation time may be extended, but in this case, the throughput is reduced. Therefore, in order to reduce the irradiation amount of polarized ultraviolet light and shorten the irradiation time, it is required to improve the sensitivity of the material used for the alignment layer to light also from the viewpoint of energy saving.

Therefore, in Patent Document 6, in order to obtain excellent photoreaction efficiency, solvent resistance, and high alignment sensitivity, among (A) a photoalignable group, and among a hydroxy group, a carboxyl group, an amino group and an alkoxysilyl group, A cured film-forming composition comprising a compound having at least one substituent selected from any one of the above and a polymer having a substituent capable of thermally reacting with the component (B) (A) and a self-crosslinkable polymer Proposed. The polymer (B) thermally reacts with the component (A) and undergoes a self-crosslinking reaction. The cured film-forming composition is cured by heating to form a cured film, and the cured film is irradiated with polarized ultraviolet light to be oriented. Layers can be formed.
According to Patent Document 6, a polymer having a substituent capable of thermally reacting with the component (B) and the component (A) is used, and a polymer capable of self-crosslinking is used, and a crosslinking agent is not separately added. Can.
However, the alignment control force is not sufficient and there is room for improvement.

Patent No. 4094764 Patent No. 4207430 gazette Patent No. 5459520 gazette International Publication No. 2011/0106635 brochure International Publication No. 2011/126022 brochure WO 2014/104320 pamphlet

  The present invention has been made in view of the above problems, and in a thermosetting composition containing a copolymer having both a photoalignment site and a thermal crosslinking site, an alignment layer having excellent liquid crystal alignment ability can be formed. It is a primary object of the present invention to provide a thermosetting composition having photoalignment properties, an alignment layer using the same, a substrate with an alignment layer, and a retardation plate.

  In order to achieve the above object, the present invention provides a copolymer having a photoalignable structural unit represented by the following formula (1) and a thermally crosslinkable structural unit having a self-crosslinkable thermally crosslinkable group. There is provided a thermosetting composition having photoalignment properties characterized by containing.

(Wherein, in the formula (1), X represents a photoalignable group, L ¹ represents a divalent linking group or a single bond, R ¹ represents a hydrogen atom or a monovalent organic group, k represents 1 to 5).

  According to the present invention, since the thermally crosslinkable structural unit of the copolymer has a self-crosslinkable thermally crosslinkable group, there is no need to separately add a crosslinking agent, and it is possible to enhance the photoreactivity and improve the sensitivity. it can. In addition, since the photoalignable structural unit of the copolymer has a styrene skeleton and contains a large amount of π electron system, the alignment layer formed using the photoalignable thermosetting composition of the present invention is The interaction with liquid crystal molecules is considered to be strong. Accordingly, an alignment layer excellent in liquid crystal alignment ability can be obtained. Furthermore, the thermosetting composition having photoalignment properties of the present invention has thermosetting properties, and can obtain an alignment layer excellent in heat resistance and solvent resistance.

  In the present invention, the photoalignable group is preferably a functional group which causes a photodimerization reaction or a photoisomerization reaction. More preferably, the photoalignable group is a cinnamoyl group. These photoalignable groups have the advantages of relatively high sensitivity to light and a wide choice of materials.

  Furthermore, in the present invention, the above-mentioned copolymer may further have a second thermally crosslinkable structural unit. It is because thermosetting can be improved.

  In the above case, the second thermally crosslinkable group contained in the second thermally crosslinkable structural unit is preferably a hydroxy group. It is because the reactivity is high.

  In the present invention, the photodimerization structure or photoisomerization structure of the photoalignable group contained in the photoalignable constitutional unit represented by the above formula (1), and the self-crosslinkable thermal crosslinking possessed by the thermally crosslinkable constitutional unit It provides an alignment layer characterized in that it contains a copolymer having a cross-linked structure of organic groups.

  According to the present invention, since the alignment layer contains a predetermined photodimerization structure or a photoisomerization structure, and a copolymer having a predetermined cross-linked structure, it has excellent liquid crystal alignment ability, heat resistance and solvent resistance. You can get it.

Furthermore, the present invention provides a substrate with an alignment layer comprising a substrate, and the above-mentioned alignment layer formed on the substrate.
According to the present invention, by having the above-mentioned alignment layer, it is possible to obtain an alignment layer excellent in liquid crystal alignment ability.

The present invention also provides a retardation plate comprising a substrate, the above-mentioned orientation layer formed on the above-mentioned substrate, and a retardation layer formed on the above-mentioned orientation layer.
According to the present invention, by having the above-mentioned alignment layer, it is possible to obtain a retardation plate which is excellent in liquid crystal alignment ability, heat resistance and solvent resistance and has excellent optical properties.

  In the present invention, it is possible to provide a thermosetting composition having photoalignment, which can form an alignment layer having excellent liquid crystal alignment ability, heat resistance and solvent resistance.

It is a schematic sectional drawing which shows an example of the board | substrate with alignment layers of this invention. It is a schematic sectional drawing which shows an example of the phase difference plate in this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display element in this invention.

  Hereinafter, the thermosetting composition having photoalignment properties of the present invention, an alignment layer using the same, a substrate with an alignment layer, and a retardation plate will be described in detail.

A. Thermosetting Composition Having Photoalignment Property The thermosetting composition having photoalignment property of the present invention comprises a photoalignment constituent unit represented by the following formula (1) and a thermally crosslinkable group capable of self-crosslinking. And a copolymer having a thermally crosslinkable structural unit.

(Wherein, in the formula (1), X represents a photoalignable group, L ¹ represents a divalent linking group or a single bond, R ¹ represents a hydrogen atom or a monovalent organic group, k represents 1 to 5).

  Here, self-crosslinking means that the same thermally crosslinkable groups or different thermally crosslinkable groups react with each other to form a crosslinked structure without using a crosslinking agent.

In the present invention, since the copolymer has a thermally crosslinkable structural unit having a thermally crosslinkable group capable of self-crosslinking, the crosslinking composition is not separately added to the thermosetting composition having photoalignment properties of the present invention. It can be used for Therefore, the content of the copolymer in the thermosetting composition having photoalignment can be relatively increased, and the content ratio of the photoalignment constituent unit contributing to orientation can be relatively increased. It can be enhanced. In general, the crosslinking agent is a low molecular weight component, and by not adding the crosslinking agent, the crosslinking agent can be prevented from coming out on the surface of the alignment layer, so-called bleed out can be prevented, and the liquid crystal alignment ability is impaired. Can be suppressed. Therefore, photoreactivity can be enhanced and sensitivity can be improved.
Furthermore, in the present invention, when the copolymer has the photoalignable structural unit represented by the above formula (1), it is possible to obtain an alignment layer having good liquid crystal alignment ability. Although the reason for this is not clear, it is inferred as follows. That is, the photoalignable constitutional unit represented by the above formula (1) has a styrene skeleton and contains a large amount of π electron system. Further, in general, many liquid crystal molecules have an aromatic ring such as a benzene ring, and similarly contain a π electron system. Therefore, the alignment layer formed of the thermosetting composition having photoalignment properties of the present invention has a strong interaction with liquid crystal molecules. This makes it easy to control the alignment of the liquid crystal molecules, and is considered to obtain good liquid crystal alignment ability.
Therefore, in the present invention, a thermosetting composition having high sensitivity and photoalignment can be formed, which can form an alignment layer with a small amount of exposure. Therefore, the present invention can reduce the irradiation amount of polarized ultraviolet light when forming the alignment layer, shorten the irradiation time, and is useful from the viewpoint of energy saving.

  Further, in the present invention, as described above, since the copolymer has the photoalignable structural unit represented by the above formula (1), the heat having the photoalignability of the present invention by the interaction of the π electron system. It is considered that the alignment layer formed of the curable composition also has high adhesion to the liquid crystal layer formed on the alignment layer.

  Moreover, the thermosetting composition which has the photo-alignment property of this invention has thermosetting property, and can obtain the orientation layer which is excellent in heat resistance and solvent resistance. In addition, since the thermosetting composition having photoalignment properties of the present invention has high sensitivity, it is possible to obtain the liquid crystal alignment ability even when the content ratio of the photoalignment constituent unit in the copolymer is relatively small. it can. Therefore, the content ratio of the thermally crosslinkable structural unit in the copolymer can be relatively increased, and heat resistance and solvent resistance can be further enhanced.

  Furthermore, because of high sensitivity, it is also suitable for mass production, and productivity of devices having an alignment layer formed from a thermosetting composition having photoalignment can also be improved.

  Hereinafter, each component in the photocurable thermosetting composition of the present invention will be described.

1. Copolymer The copolymer used in the present invention has a photoalignable structural unit represented by the above formula (1) and a thermally crosslinkable structural unit having a self-crosslinkable thermally crosslinkable group. .
Hereinafter, each structural unit in the copolymer will be described.

(1) Photoalignable Structural Unit The photoalignable structural unit in the present invention is represented by the following formula (1).

(Wherein, in the formula (1), X represents a photoalignable group, L ¹ represents a divalent linking group or a single bond, R ¹ represents a hydrogen atom or a monovalent organic group, k represents 1 to 5).

  The photoalignable structural unit is a site that exhibits anisotropy by causing a photoreaction by light irradiation. The photoreaction is preferably a photodimerization reaction or a photoisomerization reaction. That is, the photoalignable structural unit is a light dimerization structural unit that expresses anisotropy by causing a light dimerization reaction by light irradiation, or light that expresses anisotropy by generating a photoisomerization reaction by light irradiation It is preferable that it is an isomerization structural unit.

  X in the above formula (1) is a photoalignable group. As described above, the photoalignable group is a functional group that exhibits anisotropy by causing a photoreaction upon irradiation with light, and is preferably a functional group that produces a photodimerization reaction or a photoisomerization reaction.

  Examples of the photoalignable group causing the photodimerization reaction include cinnamoyl group, chalcone group, coumarin group, anthracene group, quinoline group, azobenzene group, stilbene group and the like. The benzene ring in these functional groups may have a substituent. As a substituent, what is necessary is just a thing which does not prevent photodimerization reaction, for example, an alkyl group, an aryl group, a cycloalkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a trifluoromethyl group, a cyano group etc. are mentioned.

  The photoalignable group causing the photoisomerization reaction is preferably one which generates a cis-trans isomerization reaction, and examples thereof include cinnamoyl group, chalcone group, azobenzene group, stilbene group and the like. The benzene ring in these functional groups may have a substituent. As a substituent, what is necessary is just a thing which does not prevent a photoisomerization reaction, for example, an alkoxy group, an alkyl group, a halogen atom, a trifluoromethyl group, a cyano group etc. are mentioned.

  Among them, the photoalignable group is preferably a cinnamoyl group. Specifically, the cinnamoyl group is preferably a group represented by the following formulas (2-1) and (2-2).

In the above formula ^{(2-1), R 11} represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group or a cycloalkyl group having 1 to 18 carbon atoms having 1 to 18 carbon atoms. However, the alkyl group, the aryl group and the cycloalkyl group may be bonded via an ether bond, an ester bond, an amide bond or a urea bond, and may have a substituent. R ¹² to R ¹⁵ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 1 to 18 aryl group or a carbon of 1 to 18 carbon atoms, having 1 to 18 carbon atoms Represents an alkoxy group or a cyano group. However, the alkyl group, the aryl group and the cycloalkyl group may be bonded via an ether bond, an ester bond, an amide bond or a urea bond, and may have a substituent. R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 18 carbon atoms.
Further, in the above formula ^{(2-2), R} 21 ~R ²⁵ independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, 1 to 18 aryl group or a carbon of 1 to 18 carbon atoms And a cycloalkyl group, an alkoxy group having 1 to 18 carbon atoms, or a cyano group. However, the alkyl group, the aryl group and the cycloalkyl group may be bonded via an ether bond, an ester bond, an amide bond or a urea bond, and may have a substituent. R ²⁶ and R ²⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 18 carbon atoms.

  In the case where the photoalignable group is a cinnamoyl group and the group represented by the above formula (2-1), the benzene ring of the styrene skeleton may be a benzene ring of a cinnamoyl group.

L ¹ in the above formula (1) is a divalent linking group or a single bond. When L ¹ is a single bond, the photoalignable group X is directly bonded to the styrene skeleton. Examples of the divalent linking group include ether bonds, thioether bonds, ester bonds, thioester bonds, carbonyl bonds, thiocarbonyl bonds, alkylene groups, arylene groups, cycloalkylene groups, and combinations thereof. Specifically, -O -, - S -, - COO -, - COS -, - CO -, - OCO -, - OCO (CH 2) n COO -, - OCO (CH 2 CH 2 O) m COO _{-, - OCOC 6 H 4 O} -, - OCOC 6 H 10 O -, - COO (CH 2) n O -, - COO (CH 2 CH 2 O) m -, - COOC 6 H 4 O -, - COOC _{6 H 10 O -, - O} (CH 2) n O -, - O (CH 2 CH 2 O) m -, - OC 6 H 4 O -, - OC 6 H 10 O -, - (CH 2) n O- and the like. n is 1-20 and m is 1-10.

R ¹ in the above formula (1) is a hydrogen atom or a monovalent organic group. The monovalent organic group is preferably a methyl group. Among them, R ¹ is preferably a hydrogen atom.

In the above formula (1), k is 1 to 5 and -L ¹ -X may be bonded to any of the ortho position, meta position and para position. When k is 2 to 5, L ¹ and X may be the same as or different from each other. Among them, k is preferably 1, and -L ¹ -X is preferably bonded at the para position. Specifically, the photoalignable structural unit is preferably a structural unit represented by the following formula (1-1). In the following formulas, each symbol is the same as the above formula (1).

  As a photoalignable structural unit, structural units represented by the following formulas (1-2) to (1-5) can be exemplified.

In the above formula (1-2), R ³¹ is the same as R ^{11 in the} above formula (2-1), and R ³² and R ³³ are the same as R ¹⁶ and R ^{17 in} the above formula (2-1) .
In the above formula (1-3), L ¹¹ represents a single bond or a divalent linking group. The divalent linking group is the same as L ^{1 in the} above formula (1). R ^{11 to} R ¹⁷ are the same as the above formula (2-1).
L < ¹² > represents a single bond or a bivalent coupling group in said Formula (1-4). As a bivalent coupling group, it is the same except removing the carbonyl bond and the thiocarbonyl bond in L ¹ of the said Formula (1).
In the formula ^{(1-5), L 13} represents a single bond or a divalent linking group. The divalent linking group is the same as L ^{1 in the} above formula (1). R ^{35 to} R ³⁷ are the same as R ^{12 to} R ¹⁵ in the above formula (2-1), and R ³⁸ and R ³⁹ are the same as R ¹⁶ and R ^{17 in} the above formula (2-1).

  The photoalignable structural unit that the copolymer has may be one type or two or more types.

Among them, the photoalignable structural unit is preferably a structural unit represented by the above formulas (1-3) and (1-4).
In the above formula (1-3), L ¹¹ is a single bond, -O-, -COO-, -OCO-, -OCO (CH ₂ ) _n COO-, -OCO (CH ₂ CH ₂ O) _m COO-, _{-OCOC 6 H 10 O -, -} COO (CH 2) n O -, - COO (CH 2 CH 2 O) m -, - COOC 6 H 10 O -, - O (CH 2) n O -, - O _{(CH 2 CH 2 O) m} -, - OC 6 H 10 O- or - _{(CH 2)} n is preferably O-. n is preferably 1 to 11, and m is preferably 1 to 5.
Moreover, it is more preferable that the photoalignable structural unit represented by said Formula (1-3) is a structural unit represented by following formula (1-6).

In the above formula ^{(1-6), R} 12 ~R ¹⁷ and ^{L 11} is the same as the above-mentioned formula (1-3). R ¹⁸ represents a hydrogen atom, an alkoxy group having 1 to 18 carbon atoms, a cyano group, an alkyl group having 1 to 18 carbon atoms, a phenyl group, a biphenyl group or a cyclohexyl group. However, the alkyl group, the phenyl group, the biphenyl group and the cyclohexyl group may be bonded via an ether bond, an ester bond, an amide bond or a urea bond. n represents 1 to 5; R ¹⁸ may be bonded at any of the ortho position, meta position and para position. When n is 2 to 5, R ¹⁸ may be the same as or different from each other. Among them, it is preferable that n is 1 and R ¹⁸ is bonded to the para position.

In the above formula ^{(1-4), L 12} represents a single _{bond, -O -, - OCOC 6 H} 10 O -, - COO (CH 2) n O -, - COO (CH 2 CH 2 O) m - _{, -COOC 6 H 10 O -,} - O (CH 2) n O -, - O (CH 2 CH 2 O) m -, - OC 6 H 10 O- or - _{(CH 2)} that n is O- Is preferred.

  When the photoalignable structural unit is a structural unit represented by the above formulas (1-6) and (1-4), an aromatic ring is disposed near the end of the photoalignable structural unit, It has a structure similar to liquid crystal molecules. Therefore, it is considered that the affinity with the liquid crystal layer formed on the alignment layer is enhanced, and the liquid crystal alignment ability and adhesion are improved.

  When the photoalignable structural unit is a structural unit represented by the above formulas (1-6) and (1-4), the photodimerization reactivity or the photoisomerization reactivity is further enhanced, and the sensitivity is increased. Can be further improved. Although the reason for this is not clear, it is inferred as follows. That is, since the photoalignable structural unit has a styrene skeleton, the stacking structure is easily formed by the interaction of the π electron systems of the styrene skeletons of the photoalignable structural unit. Further, in the photoalignable structural units represented by the above formulas (1-6) and (1-4), the photoalignable group and the styrene skeleton are close to each other. As a result, it is presumed that the photoalignable group is in a positional relationship that is likely to cause a photodimerization reaction or a photoisomerization reaction. For example, in the case of a photoisomerization reaction, the styrene skeletons of the photoalignable structural units are stacked together, and the photoalignable group and the styrene skeleton are close to each other, so that the directions of the photoalignable groups are uniform. It is considered that the photoisomerization reactivity is enhanced. In addition, in the case of the photodimerization reaction, the styrene skeletons of the photoalignable structural unit are stacked together, and the distance between the photoalignable groups is short due to the proximity of the photoalignable group and the styrene skeleton. It is considered that the photodimerization reactivity is enhanced.

  For the synthesis of the copolymer, a styrenic monomer having a photoalignable group that forms the photoalignable structural unit can be used. The styrenic monomer having a photoalignable group can be used alone or in combination of two or more.

The content ratio of the photoalignable structural unit in the copolymer can be set in the range of 10 mol% to 90 mol%, preferably 20 mol% to 100 mol%, when the entire copolymer is 100 mol%. It is within the range of 80 mol%. When the content ratio of the photoalignable structural unit is small, the sensitivity may be reduced, and it may be difficult to impart a good liquid crystal alignment ability. In addition, when the content ratio of the photoalignable structural unit is large, the content ratio of the thermally crosslinkable structural unit relatively decreases, sufficient thermosetting property can not be obtained, and it is difficult to maintain good liquid crystal alignment ability May be
In addition, the content rate of each structural unit in a copolymer can be calculated from the integral value by ¹ H NMR measurement.

(2) Thermally Crosslinkable Structural Unit The thermally crosslinkable structural unit in the present invention is one having a thermally crosslinkable group capable of self-crosslinking.

  As a self-crosslinkable thermally crosslinkable group, for example, a glycidyl group, an amido group, an N-alkoxymethyl group, an N-hydroxymethyl group, a phenolic hydroxy group whose ortho position is substituted by a hydroxymethyl group or an alkoxymethyl group, etc. It can be mentioned.

As a monomer unit which comprises a thermally crosslinkable structural unit, acrylic acid ester, methacrylic acid ester, styrene, acrylamide, methacrylamide, maleimide, vinyl ether, vinyl ester etc. are mentioned, for example. Among them, acrylic ester, methacrylic ester, acrylamide, methacrylamide and styrene are preferable.
Acrylic acid ester and methacrylic acid ester monomers have the advantages of high solubility, easy availability as commercial products, and good reactivity in copolymerization.
In addition, monomers of acrylamide and methacrylamide in which a self-crosslinkable thermally crosslinkable group such as N-alkoxymethyl group or N-hydroxymethyl group is bonded are easily available as commercial products and have an advantage of good reactivity. .
Moreover, in the case of styrene, in the copolymer, not only the photoalignable structural unit but also the thermally crosslinkable structural unit have a styrene skeleton, whereby a copolymer containing a large amount of π electron system can be obtained. Therefore, when an alignment layer is formed using the thermosetting composition having photoalignment properties of the present invention, the liquid crystal alignment ability is improved by the interaction of the π electron system, and the adhesion to the liquid crystal layer is enhanced. It is believed that

  As a thermally crosslinkable structural unit, the structural unit represented by following formula (3) can be illustrated.

In the above formula (3), Z ¹ represents a monomeric unit, for example, acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, styrene, maleimide, vinyl ethers, vinyl esters, and the like. Among them, as described above, acrylic esters, methacrylic esters, acrylamides, methacrylamides and styrenes are preferable. Specifically, monomer units represented by the following formula can be mentioned.

(Wherein R ⁴¹ represents a hydrogen atom, a methyl group, a chlorine atom or a phenyl group, R ⁴² represents a hydrogen atom or a methyl group, R ⁴³ represents a hydrogen atom, a methyl group, a chlorine atom or a phenyl group, R ⁴⁴ Represents a hydrogen atom or a lower alkyl group.)
When the monomer unit is styrene, -L ² -Y ¹ may be bonded at any of the ortho position, the meta position and the para position, and may be bonded in plural. In the plural cases, L ² and Y ¹ may be the same as or different from each other. Among them, it is preferable that one -L ² -Y ¹ be bonded to the para position.

In the above formula (3), Y ¹ represents a self-crosslinkable thermally crosslinkable group, and as described above, for example, glycidyl group, amido group, N-alkoxymethyl group, N-hydroxymethyl group, ortho position is hydroxymethyl And a phenolic hydroxy group substituted by a group or an alkoxymethyl group.

In the above formula (3), L ² represents a single bond or a divalent linking group. When L ² is a single bond, the self-crosslinkable thermally crosslinkable group Y ¹ is directly bonded to the monomer unit Z ¹ . Examples of the divalent linking group include ether bonds, thioether bonds, ester bonds, thioester bonds, carbonyl bonds, thiocarbonyl bonds, alkylene groups, arylene groups, cycloalkylene groups, and combinations thereof.

When Z ¹ is styrene, Y ¹ is a phenolic hydroxy group substituted at the ortho position with a hydroxymethyl group or an alkoxymethyl group, and L ² is a single bond, the benzene ring of the styrene skeleton is a phenolic hydroxy group. It becomes a benzene ring of a group.

  As a monomer which forms such a thermally crosslinkable structural unit, an acrylic acid ester compound, a methacrylic acid ester compound, an acrylamide compound, a methacrylamide compound, a styrene compound, a maleimide compound, a vinyl compound etc. are mentioned, for example.

  The thermally crosslinkable structural unit that the copolymer has may be one type or two or more types.

  For the synthesis of the copolymer, a monomer having a self-crosslinkable thermally crosslinkable group which forms the above-mentioned thermally crosslinkable structural unit can be used. The monomers having a self-crosslinkable thermally crosslinkable group can be used alone or in combination of two or more.

  The content of the thermally crosslinkable structural unit in the copolymer can be set in the range of 1 mol% to 90 mol%, preferably 5 mol% to 100 mol%, based on 100 mol% of the entire copolymer. It is within the range of 80 mol%. When the content ratio of the thermally crosslinkable structural unit is small, sufficient thermosetting property may not be obtained, and it may be difficult to maintain good liquid crystal alignment ability. In addition, when the content ratio of the thermally crosslinkable structural unit is large, the content ratio of the photoalignable structural unit relatively decreases, the sensitivity may be reduced, and it may be difficult to impart a good liquid crystal alignment ability. .

(3) Second Thermally Crosslinkable Structural Unit In the present invention, the copolymer may have a second thermally crosslinkable structural unit in addition to the above-mentioned thermally crosslinkable structural unit. The second thermally crosslinkable structural unit is a self-crosslinkable thermally crosslinkable group possessed by the thermally crosslinkable structural unit upon heating, or a site to be bonded to a crosslinking agent. The thermosetting property can be enhanced by the inclusion of the second thermally crosslinkable structural unit in the copolymer.

  The second thermally crosslinkable structural unit has a second thermally crosslinkable group, and the second thermally crosslinkable group is usually one that does not self-crosslink. Examples of the second thermally crosslinkable group include a hydroxy group, a carboxy group, a phenolic hydroxy group, a mercapto group, a glycidyl group, and an amide group. Among them, from the viewpoint of reactivity, aliphatic hydroxy groups are preferable, and primary hydroxy groups are more preferable.

  Examples of the monomer unit constituting the second thermally crosslinkable structural unit include acrylic ester, methacrylic ester, styrene, acrylamide, methacrylamide, maleimide, vinyl ether, vinyl ester and the like. Among them, acrylic acid esters, methacrylic acid esters, and styrene are preferable as in the above-mentioned thermally crosslinkable structural unit.

  As a 2nd thermally crosslinkable structural unit, the structural unit represented by following formula (4) can be illustrated.

In the formula (4), Z ² represents a monomeric unit, for example, acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, styrene, maleimide, vinyl ethers, vinyl esters, and the like. Among them, as described above, acrylic esters, methacrylic esters and styrene are preferable. In addition, since it can be made the same as that of the monomer unit of the said thermally crosslinkable structural unit about the specific monomer unit, description here is abbreviate | omitted.

In the above formula (4), Y ² represents a second thermally crosslinkable group, and examples thereof include a hydroxy group, a carboxy group, a phenolic hydroxy group, a mercapto group, a glycidyl group, and an amide group. Among them, as described above, from the viewpoint of reactivity, aliphatic hydroxy groups are preferable, and primary hydroxy groups are more preferable.

In the above formula (4), L ³ represents a single bond or a divalent linking group. When L ³ is a single bond, the second thermally crosslinkable group Y ² is directly bonded to the monomer unit Z ² . Examples of the divalent linking group include ether bonds, thioether bonds, ester bonds, thioester bonds, carbonyl bonds, thiocarbonyl bonds, alkylene groups, arylene groups, cycloalkylene groups, and combinations thereof. Among these, a divalent linking group is, - _{(CH 2) n} - or _{- (C 2 H 4 O)} m - preferably has a, n represents 4 to 11, m is preferably 2-5. If n and m are too small, the distance between the second thermally crosslinkable group and the main skeleton of the copolymer in the second thermally crosslinkable constituent unit becomes short, so that the above thermally crosslinkable structural unit in the second thermally crosslinkable group The heat crosslinkable group or the crosslinker is difficult to bond, and the reactivity between the second heat crosslinkable structural unit and the heat crosslinkable structural unit or the crosslinker may be reduced. On the other hand, when n and m are too large, the chain length of the linking group in the second thermally crosslinkable structural unit becomes long, so the terminal second thermally crosslinkable group is difficult to come out to the surface, and the second thermally crosslinkable group The thermally crosslinkable group of the thermally crosslinkable structural unit and the crosslinking agent become difficult to bond, and the reactivity of the second thermally crosslinkable structural unit with the thermally crosslinkable structural unit or the crosslinker may be lowered.

For example, when L ³ is — (C ₂ H ₄ O) _m — and Y ² is a hydroxy group, −L ³ —Y ² is — (C ₂ H ₄ O) _{m —} H be able to.

In the above formula (4), the second thermally crosslinkable group Y ² is bonded to the monomer unit Z ² via a divalent linking group or a single bond L ³ , but Y ² is a carboxy group or a hydroxy group In the case of a group, the second thermally crosslinkable structural unit represented by the above formula (4) may be a structural unit represented by the following formula. In the following formulas, each symbol is the same as the above formula.

  As a monomer which forms such a 2nd thermally crosslinkable structural unit, an acrylic acid ester compound, a methacrylic acid ester compound, an acrylamide compound, a methacrylamide compound, a styrene compound, a maleimide compound, a vinyl compound etc. are mentioned, for example.

  As the acrylic acid ester compound and methacrylic acid ester compound, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2,3-Dihydroxypropyl acrylate, 2,3-Dihydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, triethylene glycol monoacrylate, tetraethylene glycol monoacrylate, dipropylene glycol monoacrylate, tripropylene glycol monoacrylate, tetra Hydrides such as propylene glycol monoacrylate Monomers having a carboxy group and an acrylic group or methacrylic group.

  Examples of acrylamide compounds and methacrylamide compounds include 2-hydroxyethyl acrylamide, 2-hydroxyethyl methacrylamide, 2-hydroxypropyl acrylamide, 2-hydroxypropyl methacrylamide, 4-hydroxybutyl acrylamide, 4-hydroxybutyl methacrylamide, etc. And monomers having a hydroxy group of and an acrylamide group or a methacrylamide group.

  Examples of the vinyl compound include monomers having a hydroxy group and a vinyl group such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, vinyl 3-hydroxypropionate and the like.

  Examples of the styrene compound include an esterified product of 4-vinylbenzoic acid and a diol, an esterified product of 4-vinylbenzoic acid and a diethylene glycol, an etherified product of a hydroxystyrene and a diol, an etherified product of a hydroxystyrene and a diethylene glycol The monomer which has a hydroxyl group and a styrene group is mentioned.

  Examples of the maleimide compound include monomers having a hydroxy group and a maleimide group such as N- (2-hydroxyethyl) maleimide, N-hydroxymaleimide and the like.

  Also, monomers having a phenolic hydroxyl group such as hydroxystyrene, N- (hydroxyphenyl) methacrylamide, N- (hydroxyphenyl) acrylamide, N- (hydroxyphenyl) maleimide, N- (hydroxyphenyl) maleimide, acrylic acid, Methacrylic acid, crotonic acid, mono- (2- (acryloyloxy) ethyl) phthalate, mono- (2- (methacryloyloxy) ethyl) phthalate, N- (carboxyphenyl) maleimide, N- (carboxyphenyl) methacrylamide, N Examples also include monomers having a carboxy group such as-(carboxyphenyl) acrylamide, and monomers having a glycidyl group such as glycidyl methacrylate and glycidyl acrylate.

  The second thermally crosslinkable structural unit contained in the copolymer may be one type or two or more types.

  For the synthesis of the copolymer, a monomer having a second thermally crosslinkable group that forms the second thermally crosslinkable structural unit can be used. The monomers having the second thermally crosslinkable group can be used alone or in combination of two or more.

  The content of the second thermally crosslinkable structural unit in the copolymer can be set in the range of 0 mol% to 50 mol%, preferably 5 mol, based on 100 mol% of the entire copolymer. % To 30 mol%. If the content ratio of the second thermally crosslinkable structural unit is small, the effect of improving the thermosetting property may not be sufficiently obtained. In addition, when the content ratio of the second thermally crosslinkable structural unit is large, the content ratio of the photoalignable structural unit relatively decreases, the sensitivity decreases, and it becomes difficult to impart a good liquid crystal alignment ability. There is.

(4) Other Structural Units In the present invention, the copolymer has a structural unit having neither a photoalignable group nor a thermally crosslinkable group, in addition to the photoalignable structural unit and the thermally crosslinkable structural unit. It may be done. By including other structural units in the copolymer, for example, the solvent solubility, heat resistance, reactivity and the like can be enhanced.

  As a monomer unit which constitutes a structural unit which does not have a photoalignable group and a thermally crosslinkable group, for example, acrylic acid ester, methacrylic acid ester, maleimide, acrylamide, acrylonitrile, maleic anhydride, styrene, vinyl, etc. It can be mentioned. Among them, acrylic acid esters, methacrylic acid esters, and styrene are preferable as in the above-mentioned thermally crosslinkable structural unit.

  As a monomer which forms a structural unit which does not have such a photo-alignment group and a thermal crosslinkable group, an acrylic acid ester compound, a methacrylic acid ester compound, a maleimide compound, an acrylamide compound, an acrylonitrile, a maleic anhydride, styrene is mentioned, for example. Compounds, vinyl compounds and the like can be mentioned. Specifically, those described in Japanese Patent No. 5459520 can be used.

  The structural unit having no photoalignable group and no thermally crosslinkable group in the copolymer may be one type or two or more types.

  The content ratio of the above constituent units in the copolymer is preferably in the range of 0 mol% to 50 mol%, and in the range of 0 mol% to 30 mol%, based on 100 mol% of the entire copolymer. It is more preferable that it is inside. When the content ratio of the structural unit is large, the content ratio of the photoalignable structural unit and the thermally crosslinkable structural unit relatively decreases, the sensitivity is lowered, and it becomes difficult to impart a good liquid crystal alignment ability. Moreover, sufficient thermosetting property may not be obtained and it may become difficult to maintain favorable liquid crystal aligning ability.

(5) Copolymer The number average molecular weight of the copolymer is not particularly limited, and may be, for example, about 3,000 to 200,000, preferably in the range of 4,000 to 100,000. It is. When the number average molecular weight is too large, the solubility in a solvent may be lowered or the viscosity may be increased to deteriorate the handleability, and it may be difficult to form a uniform film. On the other hand, if the number average molecular weight is too small, curing may be insufficient at the time of heat curing, and solvent resistance and heat resistance may be reduced.
The number average molecular weight can be measured by gel permeation chromatography (GPC).

As a method of synthesizing the copolymer, a method of copolymerizing a styrenic monomer having a photoalignable group and a monomer having a thermally crosslinkable group capable of self-crosslinking can be mentioned.
The method of synthesizing the copolymer is not particularly limited. For example, polymerization is performed in a solvent in which a styrenic monomer having a photoalignable group, a monomer having a thermally crosslinkable group capable of self-crosslinking, a polymerization initiator, etc. It can be obtained by reaction. In that case, the solvent to be used is not particularly limited as long as it dissolves a styrenic monomer having a photoalignable group, a monomer having a thermally crosslinkable group capable of self-crosslinking, a polymerization initiator and the like. Specifically, the solvent may be the same as the solvent used for the thermosetting composition having photoalignment described later. Moreover, the temperature in the case of a polymerization reaction can be set, for example at about 50 degreeC-120 degreeC. The copolymer obtained by the above method is usually in the form of a solution dissolved in a solvent.

Although the copolymer obtained by the said method can be used as it is, it can also be refine | purified and used by the method shown below.
That is, the solution of the copolymer obtained by the above method is added to diethyl ether under stirring, methanol, water and the like to cause reprecipitation, and the formed precipitate is filtered and washed, and then under normal pressure or reduced pressure. It can be dried at room temperature or dried by heating to form a copolymer powder. By this operation, the polymerization initiator coexisting with the copolymer and the unreacted monomer can be removed, and as a result, a purified copolymer powder can be obtained. If sufficient purification can not be performed by one operation, the obtained powder may be redissolved in a solvent and the above operation may be repeated.

  The copolymer may be used in the form of a solution when the copolymer is synthesized, or in the form of a powder, or in the form of a solution in which the purified powder is redissolved in a solvent described later.

  The copolymer may be of one type or a mixture of two or more types of copolymers.

2. Crosslinking Agent The photoalignable thermosetting composition of the present invention may contain a crosslinking agent. The crosslinking agent is to be bonded to the thermally crosslinkable structural unit or the second thermally crosslinkable structural unit of the above-mentioned copolymer, and can enhance the thermosetting property, the heat resistance and the solvent resistance. However, from the viewpoint of photoreactivity and sensitivity, the thermosetting composition having photoalignment properties of the present invention preferably does not contain a crosslinking agent.

As a crosslinking agent, an epoxy compound, a methylol compound, an isocyanate compound etc. are mentioned, for example. Among them, methylol compounds are preferable.
The crosslinking agent may be a compound obtained by condensing a melamine compound, a urea compound, a glycoluril compound and a benzoguanamine compound in which the hydrogen atom of the amino group is substituted with a methylol group or an alkoxymethyl group.
Furthermore, as the crosslinking agent, a polymer produced by using an acrylamide compound or a methacrylamide compound substituted with a hydroxymethyl group or an alkoxymethyl group can also be used.
Specifically, those described in Japanese Patent No. 5459520 can be used.

  In addition, a crosslinking agent containing a plurality of benzene rings in the molecule can also be used. As a crosslinking agent containing a plurality of benzene rings in the molecule, for example, a phenol derivative having a total of two or more hydroxymethyl groups or alkoxymethyl groups and having a molecular weight of 1200 or less, or at least two free N-alkoxymethyl groups And melamine-formaldehyde derivatives and alkoxymethyl glycoluril derivatives. The phenol derivative having a hydroxymethyl group can be obtained by reacting formaldehyde with a phenol compound having no corresponding hydroxymethyl group under base catalysis.

  These crosslinking agents can be used alone or in combination of two or more.

  The content of the crosslinking agent in the thermosetting composition having photoalignment properties of the present invention is preferably in the range of 1 part by mass to 40 parts by mass with respect to 100 parts by mass of the above-mentioned copolymer, and more preferably It is in the range of 2 mass parts-30 mass parts. If the content is too small, the heat resistance and solvent resistance of the cured film formed from the thermosetting composition having photoalignment may be lowered, and the liquid crystal alignment ability may be lowered. In addition, when the content is too large, the liquid crystal alignment ability and storage stability may be lowered.

3. Acid or Acid Generator The photoalignable thermosetting composition of the present invention may contain an acid or acid generator. The acid or acid generator can accelerate the thermosetting reaction of the photoalignable thermosetting composition of the present invention.

  As an acid or acid generator, a compound containing a sulfonic acid group, hydrochloric acid or a salt thereof, and a compound which thermally decomposes upon drying and heat curing of a coating to generate an acid, that is, thermally decomposed at a temperature of 50 ° C. to 250 ° C. It will not be specifically limited if it is a compound which generate | occur | produces an acid. Specifically, those described in Japanese Patent No. 5459520 can be used.

  The content of the acid or acid generator in the thermosetting composition having photoalignment properties of the present invention is preferably in the range of 0.01 parts by mass to 20 parts by mass with respect to 100 parts by mass of the above-mentioned copolymer, More preferably, it is in the range of 0.05 parts by mass to 10 parts by mass, and more preferably in the range of 0.1 parts by mass to 5 parts by mass. By making content of an acid or an acid generator into the said range, sufficient thermosetting and solvent resistance can be provided, and also the high sensitivity with respect to light irradiation can also be provided. On the other hand, if the content is too large, the storage stability of the thermosetting composition having photoalignment may be reduced.

4. Sensitizer The thermosetting composition having photoalignment properties of the present invention may contain a sensitizer. The photosensitizer such as photodimerization reaction or photoisomerization reaction can be promoted by the sensitizer.

  As the sensitizer, specifically, those described in Japanese Patent No. 5459520 can be used. Among them, benzophenone derivatives and nitrophenyl compounds are preferable. The sensitizers can be used alone or in combination of two or more compounds.

  The content of the sensitizer in the thermosetting composition having photoalignment properties of the present invention is preferably in the range of 0.1 parts by mass to 20 parts by mass with respect to 100 parts by mass of the copolymer, More preferably, it is in the range of 0.2 parts by mass to 10 parts by mass. When the content is too small, the effect as a sensitizer may not be obtained sufficiently, and when the content is too large, the transmittance may be reduced and the coating may be roughened.

5. Solvent The thermosetting composition having photoalignment properties of the present invention is mainly used in the form of a solution dissolved in a solvent.
The solvent is not particularly limited as long as it can dissolve the components described above, and specifically, those described in Japanese Patent No. 5459520 can be used. The solvents can be used singly or in combination of two or more.

6. Additives The thermosetting composition having photoalignment properties of the present invention may, if necessary, be a silane coupling agent, surfactant, rheology modifier, pigment, dye, storage, as long as the effects of the present invention are not impaired. Stabilizers, antifoaming agents, antioxidants and the like can be contained. In addition, a liquid crystalline monomer can be contained to improve the liquid crystal alignment ability.

7. Thermosetting Composition Having Photoalignment Properties The thermosetting composition having photoalignment properties of the present invention is usually used as a solution in which each component is dissolved in a solvent. The proportion of the solid content in the thermosetting composition having photoalignment properties of the present invention is not particularly limited as long as each component is uniformly dissolved in the solvent, and 0.1% by mass to 80% by mass It is in a range, preferably in a range of 0.5% by mass to 60% by mass, and more preferably in a range of 0.5% by mass to 40% by mass. If the proportion of the solid content is too low, it may be difficult to impart liquid crystal alignment ability and thermosetting properties. On the other hand, when the proportion of the solid content is too large, the viscosity of the thermosetting composition having photoalignment is high, and it becomes difficult to form a uniform film.
In addition, solid content means what remove | eliminated the solvent from all the components of the thermosetting composition which has photo-alignment property.

The method of preparing the thermosetting composition having photoalignment properties of the present invention is not particularly limited, but since the storage stability becomes long, a copolymer, a crosslinking agent, a sensitizer and other additives are obtained. And the acid or acid generator is added later. When the acid or acid generator is added from the beginning, it is preferable to use, as the acid or acid generator, a compound which is thermally decomposed during drying and heat curing of the coating to generate an acid.
In the preparation of the thermosetting composition having photoalignment properties of the present invention, a solution of a copolymer obtained by a polymerization reaction in a solvent can be used as it is. In this case, as described above, a crosslinking agent, a sensitizer and other additives are added to the solution of the copolymer to form a uniform solution, and an acid or an acid generator is then added. At this time, a solvent may be further added for the purpose of adjusting the concentration. At this time, the solvent used in the formation process of the copolymer may be the same as or different from the solvent used for adjusting the concentration of the thermosetting composition having photoalignment.

  Moreover, it is preferable to use, after filtering the solution of the thermosetting composition which has the prepared photo-alignment property using a filter with a hole diameter of about 0.2 micrometer, etc.

8. Applications Examples of applications of the thermosetting composition having photoalignment properties of the present invention include alignment layers of various optical elements such as retardation plates, and alignment layers of liquid crystal display elements. Moreover, the thermosetting composition which has the photoalignment property of this invention can also be used for the insulating film, protective film, etc. in various devices, such as a liquid crystal display element, an organic EL element, TFT, a color filter, For example, an organic EL element , An interlayer insulating film of a TFT, an overcoat layer of a color filter, and the like.

B. Alignment layer The alignment layer of the present invention is a photodimerization structure or a photoisomerization structure of a photoalignment group of the photoalignment constituent unit represented by the above formula (1), and a self-crosslinking component which the heat crosslinkable construction unit has. It is characterized in that it contains a copolymer having a crosslinked structure of possible thermally crosslinkable groups.

  Here, the crosslinked structure refers to a three-dimensional network structure. The crosslinked structure does not include a structure in which the photoalignable groups are crosslinked by the photodimerization reaction.

  According to the present invention, since the alignment layer contains a predetermined photodimerization structure or a photoisomerization structure, and a copolymer having a predetermined cross-linked structure, it has excellent liquid crystal alignment ability, heat resistance and resistance. Solvent property can be obtained.

The copolymer is thermally crosslinked having the photoalignable structural unit represented by the above formula (1) described in “A. Thermosetting composition having photoalignability” and a thermally crosslinkable group capable of self-crosslinking. It can be formed by heat curing a copolymer having a structural unit and photoalignment.
The crosslinked structure is a three-dimensional network structure in which a self-crosslinkable thermally crosslinkable group possessed by the thermally crosslinkable structural unit is crosslinked. Usually, the thermally crosslinkable group which the thermally crosslinkable structural unit has is self-crosslinked. Accordingly, the crosslinked structure is a structure in which the thermally crosslinkable groups are crosslinked by heating. In addition, when the thermosetting composition having photoalignment properties further contains a crosslinking agent, the thermally crosslinkable group contained in the thermally crosslinkable structural unit is also bonded to the crosslinking agent, and thus the thermally crosslinkable group in the crosslinked structure is Also included are structures in which the crosslinking agent is crosslinked by heating.

In addition, about each structural unit of a copolymer, since it described in said "A. thermosetting composition which has photo-alignment property" in detail, description here is abbreviate | omitted.
The fact that the alignment layer contains the above-mentioned copolymer can be confirmed by collecting and analyzing the material from the alignment layer. As an analysis method, NMR, IR, GC-MS, XPS, TOF-SIMS and a combination of these can be applied.

The photodimerization structure in the copolymer is a structure in which the photoalignable groups of the photoalignable structural unit represented by the formula (1) are crosslinked by a photodimerization reaction, and is a structure having a cyclopropane skeleton.
The photodimerization reaction is a reaction as shown below, and is a reaction in which an olefin structure contained in a photoalignable group forms a cyclopropane skeleton by photoreaction. Xa to Xd and Xa 'to Xd' differ depending on the type of photoalignable group.

  The photodimerization structure is preferably a photodimerization structure of cinnamoyl group. Specifically, a structure in which the cinnamoyl groups described in the above-mentioned “A. Thermosetting composition having photoalignment properties” are crosslinked by photodimerization reaction is preferable. Among them, the alignment layer preferably has a photodimerization structure as represented by the following formulas (5-1) and (5-2). In the following formulas, each symbol is the same as the above formulas (1-6) and (1-4).

  When the alignment layer has a photodimerization structure as represented by the above formulas (5-1) and (5-2), a large number of aromatic rings are arranged and a large number of π electrons are contained. Therefore, the affinity with the liquid crystal layer formed on the alignment layer is enhanced, the liquid crystal alignment ability is improved, and the adhesion with the liquid crystal layer is considered to be enhanced.

Moreover, the photoisomerization structure in a copolymer is a structure where the photoalignable group which the photoalignable structural unit represented by said Formula (1) has is isomerized by photoisomerization reaction. For example, in the case of a cis-trans isomerization reaction, the photoisomerization structure may be either a structure in which a cis isomer is changed to a trans isomer or a structure in which a trans isomer is changed to a cis isomer.
For example, when the photoalignable group is a cinnamoyl group, the photoisomerization reaction is a reaction as shown below, and is a reaction in which the olefin structure contained in the photoalignable group forms a cis form or a trans form by photoreaction. . Xa to Xd differ depending on the type of photoalignable group.

  The photoisomerization structure is preferably a photoisomerization structure of a cinnamoyl group. Specifically, a structure in which the cinnamoyl group described in the above-mentioned “A. Thermosetting composition having photoalignment property” is isomerized by photoisomerization reaction is preferable. In this case, the photoisomerization structure may be either a structure in which the cis isomer is changed to trans or a structure in which the trans isomer is changed to cis. Among them, the alignment layer preferably has a photoisomerization structure of a cinnamoyl group represented by the above formula (1-3) as represented by the following formula.

  In addition, it can be analyzed by NMR or IR that the orientation layer has the said photodimerization structure or a photoisomerization structure.

  The alignment layer may contain a crosslinking agent, an acid or acid generator, a sensitizer and other additives. In addition, about these additives, it is the same as that of what was described in said "A. thermosetting composition which has photo-alignment property."

The alignment layer is formed of the thermosetting composition having the above-described photoalignment.
Here, an alignment layer formed of a thermosetting composition having photoalignment properties refers to an alignment layer formed by thermally curing a film containing a thermosetting composition having photoalignment properties and further photoalignment. Say. That is, in the formation of the alignment layer, first, a thermosetting composition having photoalignment properties is coated on a substrate, dried, and heated to form a cured film. Next, the cured film is irradiated with polarized ultraviolet light to form an alignment layer.

  It will not be specifically limited if it is a method which can form a uniform film | membrane on a board | substrate as a coating method of the thermosetting composition which has photo-alignment property, For example, a spin coat method, a roll coat method, a rod bar coat And spray coating, air knife coating, slot die coating, wire bar coating, flow coating, ink jet, and the like.

  For drying of the coating film, for example, a hot plate or an oven can be used. The temperature can be set, for example, at about 30 ° C. to 160 ° C., preferably in the range of 50 ° C. to 140 ° C. The time can be set, for example, in the range of about 20 seconds to 60 minutes, and preferably in the range of 30 seconds to 10 minutes.

  A hot plate, an oven, etc. can be used also for the heat-hardening of a coating film. The temperature can be set, for example, at about 30 ° C to 250 ° C. The time can be set, for example, in about 20 seconds to 60 minutes. Also, drying and heat curing of the coating may be performed simultaneously or separately.

  The film thickness of the cured film obtained by thermosetting the thermosetting composition having photoalignment is appropriately selected according to the application etc., and can be, for example, about 0.05 μm to 30 μm. In addition, when the film thickness of a cured film is too thin, sufficient liquid crystal aligning ability may not be obtained.

  By irradiating polarized ultraviolet light to the obtained cured film, a photoreaction can be caused to exhibit anisotropy. The wavelength of polarized ultraviolet light is usually in the range of 150 nm to 450 nm. Further, the irradiation direction of polarized ultraviolet light can be perpendicular or oblique to the substrate surface.

  In addition, it can be confirmed by collecting and analyzing the material from the alignment layer that the alignment layer is formed from the thermosetting composition having the above-described photo-alignment property. As an analysis method, NMR, IR, GC-MS, XPS, TOF-SIMS and a combination of these can be applied.

C. Substrate with Alignment Layer The substrate with alignment layer of the present invention is characterized by having a substrate and the above-mentioned alignment layer formed on the substrate.

  FIG. 1 is a schematic cross-sectional view showing an example of the alignment layer-provided substrate of the present invention. In the alignment layer-provided substrate 1 illustrated in FIG. 1, the alignment layer 3 is formed on the substrate 2.

  According to the present invention, by having the above-mentioned alignment layer, excellent liquid crystal alignment ability, heat resistance and solvent resistance can be obtained.

  Hereinafter, each structure in the board | substrate with an orientation layer of this invention is demonstrated.

1. Alignment layer The alignment layer in the present invention is the above-mentioned alignment layer and has a function of aligning liquid crystal molecules.
In addition, about the orientation layer, since it described in the said "B. orientation layer" in detail, description here is abbreviate | omitted.

2. Substrate The substrate used in the present invention supports the alignment layer.
The substrate is not particularly limited, and may be appropriately selected depending on the application and the like. Examples of the material of the substrate include glass, quartz, polyethylene terephthalate, polycarbonate, triacetyl cellulose, polyester, polysulfone, polyether sulfone, cyclic polyolefin, resin such as acrylic, metal such as aluminum, and ceramic such as silicon or silicon nitride. Etc. In addition, the substrate may be subjected to surface treatment.
The substrate may or may not have flexibility, and is appropriately selected depending on the application and the like.

3. Conductive Layer In the present invention, a conductive layer may be formed between the substrate and the alignment layer. The conductive layer functions as, for example, an electrode of various devices. Examples of the material of the conductive layer include transparent conductive materials such as ITO and IZO, and metal materials such as aluminum, molybdenum and chromium.

4. Applications Examples of applications of the alignment layer-provided substrate of the present invention include various optical elements such as a retardation plate, a liquid crystal display element, and a light emitting element.

D. Retardation Plate The retardation plate of the present invention is characterized by having a substrate, the above-mentioned alignment layer formed on the substrate, and a retardation layer formed on the alignment layer.

  FIG. 2 is a schematic cross-sectional view showing an example of the retardation plate of the present invention. In the retardation plate 10 illustrated in FIG. 2, the alignment layer 12 is formed on the substrate 11, and the retardation layer 13 is formed on the alignment layer 12.

  According to the present invention, by having the above-mentioned alignment layer, excellent liquid crystal alignment ability, heat resistance and solvent resistance can be obtained.

  In addition, about a board | substrate and an orientation layer, since it described in said "C. substrate with an orientation layer", description here is abbreviate | omitted. Hereinafter, other configurations in the retardation plate of the present invention will be described.

1. Retardation Layer The retardation layer in the present invention is formed on the alignment layer.
The retardation layer can be obtained by applying a liquid crystal composition on the alignment layer, heating to the phase transition temperature of the liquid crystal composition, aligning the liquid crystal molecules by the alignment layer, and curing.
The liquid crystal composition contains at least a liquid crystal compound, and usually further contains a solvent. The liquid crystal composition may further contain other components as long as the alignment of the liquid crystal compound is not inhibited.
As a liquid crystal composition, those generally used in retardation layers can be used. Examples of the liquid crystal composition include those having alignment properties such as horizontal alignment, cholesteric alignment, vertical alignment, hybrid alignment and the like, and are appropriately selected according to the combination with the alignment layer, desired retardation, and the like.
Among them, the liquid crystal compound is preferably a polymerizable liquid crystal compound having a polymerizable group. This is because the polymerizable liquid crystal compounds can be cross-linked to increase the stability of the retardation plate.
The film thickness, formation method and the like of the retardation layer can be the same as those of a general retardation layer.

2. A conductive layer may be formed between the retardation plate substrate and the alignment layer. In addition, about a conductive layer, since it described in the said "C. board | substrate with an orientation layer", description here is abbreviate | omitted.
The retardation plate may or may not have flexibility.

E. Device The device of the present invention is characterized by having the above-mentioned alignment layer.

The device is not particularly limited as long as it has an alignment layer, and examples thereof include various optical elements such as a retardation plate, a liquid crystal display element, and a light emitting element.
In addition, about a phase difference plate, since it described in said "D. phase difference plate", description here is abbreviate | omitted.
Hereinafter, the liquid crystal display element will be described.

(Liquid crystal display element)
The liquid crystal display element in the present invention has two aspects. Each aspect will be separately described below.

(1) First Mode In the first mode of the liquid crystal display element in the present invention, a first alignment layer-provided substrate having a first alignment layer formed on a first substrate, and a second alignment layer formed on a second substrate And a liquid crystal layer disposed between the first alignment layer-attached substrate and the second alignment layer-attached substrate, wherein the first alignment layer and the second alignment layer are as described above. It is an orientation layer.

  FIG. 3 is a schematic cross-sectional view showing an example of the liquid crystal display element in the present invention. The liquid crystal display element 20 illustrated in FIG. 3 is disposed between the first alignment layer-attached substrate 21a, the second alignment layer-attached substrate 21b, and the first alignment layer attached substrate 21a and the second alignment layer-attached substrate 21b. And a liquid crystal layer 25. In the first alignment layer-attached substrate 21a, the first electrode 23a and the first alignment layer 24a are sequentially laminated on the first substrate 22a, and in the second alignment-layer attached substrate 21b, the second electrode is formed on the second substrate 22b. 23 b and the second alignment layer 24 b are stacked in order.

  As a liquid crystal composition used for a liquid crystal layer, what is generally used for a liquid crystal layer can be used. For example, nematic liquid crystals, smectic liquid crystals, or the like can be used. In addition, the film thickness, formation method, and the like of the liquid crystal layer can be similar to those of a general liquid crystal layer.

In addition, a conductive layer is generally formed as an electrode between at least one of the first substrate and the alignment layer and between the second substrate and the alignment layer.
The first substrate, the second substrate, the alignment layer and the conductive layer are the same as the substrate, the alignment layer and the conductive layer in the above-mentioned “B. substrate with alignment layer”, and therefore the description thereof is omitted here.
In addition, other configurations of the liquid crystal display element can be the same as the configurations of a general liquid crystal display element.

(2) Second Aspect A second aspect of the liquid crystal display element in the present invention comprises the above retardation plate.
The structure of the liquid crystal display element can be the same as that of a general liquid crystal display element. For example, a retardation plate may be disposed outside the substrate constituting the liquid crystal display element, and the substrate constituting the liquid crystal display element also serves as the substrate constituting the retardation plate, and the alignment layer and A phase difference layer may be disposed.

  The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and it has substantially the same configuration as the technical idea described in the claims of the present invention, and any one having the same function and effect can be used. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples.

Synthesis Example 1 Synthesis of Self-Crosslinkable Monomer 2 In a 200 mL flask under a nitrogen atmosphere, 20.0 g (118 mmol) of p-acetoxystyrene is dissolved in 80 mL of ethyl acetate, and sodium methoxide 9.08 g (47.1 mmol) Was slowly dropped over about 30 minutes. After stirring for one and a half hours and confirming completion of the reaction by TLC, 56.0 mL (944 mmoL) of 37% formalin aqueous solution was slowly added to this solution at room temperature. Furthermore, after stirring at 40 degreeC under nitrogen atmosphere for 24 hours, it injected | threw-in to 200 mL of water in a beaker. While cooling with an ice bath, a 2.0 wt% aqueous acetic acid solution was slowly added until pH 5.0 was reached. The precipitate was separated by filtration, thoroughly washed with water, dried, and purified by column chromatography to obtain self-crosslinkable monomer 1.

Synthesis Example 2 Synthesis of Self-Crosslinkable Monomer 2 In a 200 mL flask under a nitrogen atmosphere, 20.0 g (118 mmol) of p-acetoxystyrene is dissolved in 80 mL of ethyl acetate, and sodium methoxide 9.08 g (47.1 mmol) Was slowly dropped over about 30 minutes. After stirring for one and a half hours, completion of the reaction was confirmed by TLC, extracted with ethyl acetate, washed with 1 N hydrochloric acid, pure water and saturated brine, and dried over sodium sulfate. The solvent was evaporated and dried to obtain a self-crosslinkable monomer derivative 1.

  In a 500 mL flask, 12 g (100 mmol) of self-crosslinkable monomer derivative 1, 16.1 g (110 mmol) of adipic acid and 1.2 g (9.8 mmol) of dimethylaminopyridine are dissolved in 130 ml of dichloromethane and N, N dissolved in 40 ml of dichloromethane 22.6 g (110 mmol) of '-dicyclohexylcarbodiimide was added dropwise over about 10 minutes. After stirring for 15 hours, the reaction solution was cooled and the precipitate was filtered off. The solvent was distilled off, methanol was added, and recrystallization gave a self-crosslinkable monomer derivative 2.

  Subsequently, 13.82 g (50 mmol) of the self-crosslinkable monomer derivative 2, 5.5 g (50 mmol) of hydroquinone and 0.176 g (1.47 mmol) of dimethylaminopyridine are dissolved in 50 ml of dichloromethane under ice cooling in a 300 mL flask, 11.3 g (55 mmol) of N, N'-dicyclohexylcarbodiimide dissolved in 10 ml of dichloromethane were added dropwise over about 10 minutes. After stirring for 15 hours, the reaction solution was cooled and the precipitate was filtered off. The solvent was distilled off, methanol was added, and recrystallization gave a self-crosslinkable monomer derivative 3.

  3.68 g (10 mmol) of a self-crosslinkable monomer derivative was added to a solution consisting of 20 mL of a 10% by weight aqueous solution of potassium hydroxide and 20 mL of ethanol, and the mixture was stirred and dissolved at room temperature. To this solution, 7.0 mL (80 mmoL) of 37% formalin aqueous solution was slowly added at room temperature. Furthermore, after stirring at 40 degreeC under nitrogen atmosphere for 24 hours, it injected | threw-in to 200 mL of water in a beaker. While cooling with an ice bath, a 2.0 wt% aqueous acetic acid solution was slowly added until pH 5.0 was reached. The precipitate was separated by filtration, thoroughly washed with water, dried, and purified by column chromatography to obtain a self-crosslinkable monomer 2.

Synthesis Example 3 Synthesis of Photoalignment Monomer 1 In a 300 mL flask, under cooling with ice, 20.15 g (136 mmol) of 4-vinylbenzoic acid, 21.0 (118 mmol) of methyl trans-4-hydroxycinnamate, dimethylamino 0.458 g (3.82 mmol) of pyridine was dissolved in 130 ml of dichloromethane, and 28.0 g (136 mmol) of N, N'-dicyclohexylcarbodiimide dissolved in 40 ml of dichloromethane was added dropwise over about 10 minutes. After stirring for 15 hours, the reaction solution was cooled and the precipitate was filtered off. The solvent was distilled off, methanol was added, and recrystallization gave 10.8 g of a photoalignable monomer 1.

Synthesis Example 4 Synthesis of Photoalignment Monomer 2 In a 200 mL flask and under a nitrogen atmosphere, 20.0 g (118 mmol) of p-acetoxystyrene is dissolved in 80 mL of ethyl acetate, and sodium methoxide 9.08 g (47.1 mmol) Was slowly dropped over about 30 minutes. After stirring for one and a half hours, completion of the reaction was confirmed by TLC, extracted with ethyl acetate, washed with 1 N hydrochloric acid, pure water and saturated brine, and dried over sodium sulfate. The solvent was distilled off and drying was performed to obtain a photoalignable monomer derivative 1.
In Synthesis Example 3, instead of using 4-vinylbenzoic acid, an equimolar amount of photoalignment monomer derivative 1 is used, and instead of using methyl trans-4-hydroxycinnamate, an equimolar amount of trans-cinnamic acid is used By condensing in the same manner as in Synthesis Example 3, a photoalignable monomer 2 was obtained.

Synthesis Example 5 Synthesis of Photoalignable Monomer 3 In Synthesis Example 3, condensation is performed in the same manner as in Synthesis Example 3 using equimolar amounts of ethylene glycol instead of methyl trans-4-hydroxycinnamate. Photoalignment monomer derivative 2 was obtained.
In Synthesis Example 3, instead of using 4-vinylbenzoic acid, an equimolar amount of photoalignment monomer derivative 2 is used, and instead of using methyl trans-4-hydroxycinnamate, an equimolar amount of trans-cinnamic acid is used By condensing in the same manner as in Synthesis Example 3, a photoalignable monomer 3 was obtained.

Synthesis Example 6 Synthesis of Thermally Crosslinkable Monomer 1 Photoalignment monomer derivative 1 was obtained in the same manner as in Synthesis Example 4. After dissolving 14.0 g (118 mmol) of photoalignment monomer derivative 1 in 100 ml of dimethylformamide in a 200 mL flask under a nitrogen atmosphere and ice zero, 7.07 g (177 mmol) of sodium hydroxide was added, and stirred for 15 minutes, 10.5 g (130 mmol) of 2-chloroethanol was added dropwise over about 10 minutes. After stirring for 16 hours, completion of the reaction was confirmed by TLC, extracted with ethyl acetate, washed with saturated aqueous hydrogen carbonate solution, 1 N hydrochloric acid, pure water and saturated brine, and dried over sodium sulfate. The heat-crosslinkable monomer 1 was obtained by evaporating the solvent and drying.

The structures of each monomer are shown in Tables 1 and 2 below.
Each monomer synthesize | combined confirmed the chemical structure by < ¹ > H NMR measurement using JEOL Co., Ltd. product JEOL JNM-LA400WB.

Preparation Example 1 Synthesis of Copolymer 1 1.42 g of glycidyl methacrylate, 3.08 g of a photoalignment monomer 1 and 44 mg of α, α′-azobisisobutyronitrile (AIBN) as a polymerization catalyst were dissolved in 25 ml of dioxane. The reaction was carried out at 90 ° C. for 6 hours. After completion of the reaction, the reaction product was purified by reprecipitation to obtain a copolymer 1. The number average molecular weight of the obtained copolymer was 22000.

Production Examples 2 to 18 Copolymers 2 to 18 were synthesized in the same manner as in Production Example 1 using a self-crosslinking monomer, a photoalignment monomer, and a thermosetting monomer.

Each copolymer is shown in Table 3 below.
The number average molecular weight (hereinafter referred to as “Mn”) of each synthesized copolymer is gel permeation chromatography (GPC) using polystyrene as a standard substance and NMP as an eluent using HLC-8220 GPC manufactured by Tosoh Corp. Calculated with.

Example 1
(Preparation of Thermosetting Composition 1)
The thermosetting composition 1 of the composition shown below was prepared.
・ Copolymer 1: 0.1 g
P-toluenesulfonic acid monohydrate (PTSA): 0.0015 g
Propylene glycol monomethyl ether (PGME): 2.1 g

(Formation of alignment layer)
The thermosetting composition prepared in Example 1 was applied to one surface of a transparent glass substrate by spin coating, and dried by heating in an oven at 100 ° C. for 1 minute to form a cured film, thereby obtaining a coated film. By polarized ultraviolet rays to 10 mJ / cm ² irradiated perpendicularly from the substrate normal line containing emission lines 313nm using Hg-Xe lamp and Gran Taylor prism to the surface of the cured film, to form an alignment layer.

(Preparation of phase difference plate)
5% by mass of a photopolymerization initiator IRGACURE 184 manufactured by BASF Corp. is added to a solution in which a liquid crystalline monomer represented by the following formula is dissolved in cyclohexanenon to a solid content of 15% by mass, and a polymerizable liquid crystal composition Was prepared.

The polymerizable liquid crystal composition was applied by spin coating on the surface of the transparent glass substrate on which the alignment layer was formed, and heated in an oven at 70 ° C. for 1 minute to form a coating. A retardation plate was manufactured by irradiating 300 mJ / cm ² of non-polarized ultraviolet light containing a 365 nm bright line onto the coated surface of the polymerizable liquid crystal composition using a Hg-Xe lamp in a nitrogen atmosphere on this substrate.

[Examples 2 to 28]
P-toluenesulfonic acid monohydrate (PTSA) or p-toluenesulfonic acid pyridinium salt (PPTS) as acid or acid generator, propylene glycol monomethyl ether (PGME) as solvent, hexamethoxymethylmelamine (HMM) as crosslinking agent Alternatively, using 1,3,4,6-tetrakis (methoxymethyl) glycoluril (TMGU), the thermosetting compositions of Examples 2 to 28 are prepared in the same manner as Example 1 to form an alignment layer. , And produced a retardation plate.
The composition of each thermosetting composition is shown in Table 4 below.

[Evaluation]
The following evaluation was performed about each obtained phase difference plate.

(Liquid crystal alignment)
Two linear polarizing plates were brought into a crossed nicol state, and a retardation plate was sandwiched therebetween, and observed visually. When the substrate is rotated, "◎" indicates that the light and dark pattern observed in the plane is very clear, "な も の" if the light and dark pattern observed in the plane is clear, and an orientation defect is observed Was evaluated as "x".

Claims (9)

And a copolymer having a photoalignable structural unit represented by the following formula (1) and a thermally crosslinkable structural unit having a self-crosslinkable thermally crosslinkable group ,
That the thermally crosslinkable thermally crosslinkable group is an amide group, an N-alkoxymethyl group, an N-hydroxymethyl group, or a phenolic hydroxy group substituted at the ortho position with a hydroxymethyl group or an alkoxymethyl group A thermosetting composition having photoalignment as a feature.

(Wherein, in the formula (1), X represents a photoalignable group, L ¹ represents a divalent linking group or a single bond, R ¹ represents a hydrogen atom or a monovalent organic group, k represents 1 to 5).   And a copolymer having a photoalignable structural unit represented by the following formula (1) and a thermally crosslinkable structural unit having a self-crosslinkable thermally crosslinkable group,
  A thermosetting composition having photoalignment properties characterized by containing no crosslinking agent.

(Wherein, in the formula (1), X is a photoalignable group, L ¹ Is a divalent linking group or a single bond, R ¹ Represents a hydrogen atom or a monovalent organic group, and k represents 1 to 5. ) The photocurable composition having photoalignment properties according to claim 1 or 2 , wherein the photoalignable group is a functional group which causes a photodimerization reaction or a photoisomerization reaction. Thermosetting composition having photoalignable according to claim 1, wherein the optical alignment group is characterized in that it is a cinnamoyl group to claim 3. The photocurable composition according to any one of claims 1 to 4, wherein the copolymer further comprises a second thermally crosslinkable structural unit. The thermosetting composition having photoalignment properties according to claim 5 , wherein the second thermally crosslinkable group contained in the second thermally crosslinkable structural unit is a hydroxy group. Photodimerization structure or photoisomerization structure of the photoalignable group which the photoalignable constitutional unit represented by the following formula (1) has, and crosslinked structure of the self-crosslinkable thermally crosslinkable group which the thermally crosslinkable constitutional unit has An alignment layer comprising a copolymer having

(Wherein, in the formula (1), X represents a photoalignable group, L ¹ represents a divalent linking group or a single bond, R ¹ represents a hydrogen atom or a monovalent organic group, k represents 1 to 5). A substrate with an alignment layer comprising: a substrate; and the alignment layer according to claim 7 formed on the substrate. A retardation plate comprising: a substrate; the alignment layer according to claim 7 formed on the substrate; and a retardation layer formed on the alignment layer.

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