JP5051417B2 - Photoinitiator and polymerizable composition - Google Patents

Description

  The present invention relates to a photoinitiator useful for producing an optical anisotropic body applied to a retardation film and the like, and a polymerizable composition containing the photoinitiator.

  A method for producing an optical anisotropic body such as a retardation film by photopolymerizing a polymerizable liquid crystal material in an aligned state is known. In addition, a method for producing a liquid crystal display element in which a polymer is formed in a liquid crystal material is known by curing the polymerizable liquid crystal material with ultraviolet rays in a liquid crystal material having no polymerizability. As a photoinitiator used for curing such a polymerizable liquid crystal material, one in which a liquid crystal skeleton is introduced is disclosed from the viewpoint of reducing volatility or improving orientation (see Patent Document 1). Furthermore, a photoinitiator that efficiently generates radicals by ultraviolet rays and has a liquid crystal skeleton to enable curing in air is also disclosed (see Patent Document 2). However, the photoinitiators described in these cited documents cannot be said to be sufficiently soluble in the polymerizable liquid crystal material, and have a good solubility in the polymerizable liquid crystal material having a liquid crystal skeleton. Was demanded.

JP-A-11-181010 European Patent Application Publication No. 1388538

  The problem to be solved by the present invention is to improve the solubility in a polymerizable liquid crystal material in a photoinitiator that efficiently generates radicals by ultraviolet rays that can be cured in air and has a liquid crystal skeleton. is there.

  As a result of studying the compound structure of the photoinitiator in order to solve the above-mentioned problems, it was found that a structure in which a specific linking group was introduced into the liquid crystal skeleton was effective, and the present invention was completed. That is, the present invention relates to the general formula (I)

(In the formula, R ¹ represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may be substituted with a halogen atom or a cyano group, and is not adjacent to —CH ₂ —. Represents —O—, —S—, —NH—, —NR ₀ —, (R ₀ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), in which oxygen atoms or sulfur atoms are not directly bonded to each other. .)-SiR _a R _b- , (R _a and R _b each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms) -CO-, -COO-, -OCO-, OCOO- , -SCO-, -COS-, -CH = CH- or -C≡C- may be substituted, R ¹ also represents P-Sp-X-, and (P represents a reactive functional group) Sp represents a spacer group or a single bond, X represents -O-, -S-, -CO-, -COO-, -OCO-, OCOO-, -SCO-, -COS-, -CH = CH- , -C≡C-, -CH = CHCOO-, -OOCCH = CH- or a single bond.) R ² and R ³ each independently represents a hydrocarbon group having 1 to 20 carbon atoms, R ⁴ And R ⁵ Each independently represents a hydrocarbon group having 1 to 20 carbon atoms, or -NR ⁴ R ⁵ represents a substituted or unsubstituted aromatic ring or alicyclic ring, and these rings are substituted with a heteroatom. A and B are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane. -2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo (2,2,2) octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5 -Diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2 , 7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene 2,7-diyl group or fluorene 2,7-diyl Group 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7-diyl group, 9,10-dihydrophenanthrene -2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene 2,7-diyl group and fluorene 2,7-diyl group are unsubstituted or substituted as 1 Or two or more F, Cl, CF ₃ , OCF ₃ or CH ₃ , wherein Y ¹ and Y ² are each independently a single bond, —COO—, —OCO—, —CH═N -, -N = CH-, -C≡C-, -CH ₂ CH _2- , -CH ₂ CH ₂ CH ₂ CH _2- , -CH ₂ CH ₂ CH ₂ O-, -OCH ₂ CH ₂ CH _{2- , -CH 2 O -, - OCH} 2 -, - CF 2 O -, - OCF 2 -, - CH = NN = CH -, - CF = CF -, - CH = CH -, - CH 2 CH 2 CH = CH-, -CH = CHCH ₂ CH _2- , -CH ₂ CH = CHCH _2- , -CH = CHCOO-, -OCOCH = CH-, -CH ₂ CH ₂ OCO-, -CH ₂ CH ₂ COO-,- COOCH ₂ CH ₂ - or -OCOCH ₂ CH ₂ - represents a, at least one _{-CH 2 CH 2 OCO -, -} CH 2 CH 2 COO -, - COOCH 2 CH 2 - the -OCOCH ₂ CH ₂ - represents, n is an integer of 0 to 2. ), A polymerizable composition containing the photoinitiator, and an optical anisotropic body that is a polymer of the polymerizable composition.

Photoinitiators of the present invention, as Y ¹ and Y ² in the backbone, at least one _{-CH 2 CH 2 OCO -, -} CH 2 CH 2 COO -, - COOCH 2 CH 2 -, - OCOCH 2 CH 2 By introducing-, the liquid crystal skeleton is given flexibility and solubility is ensured. Adding excessive flexibility to the liquid crystal skeleton tends to impair liquid crystal properties such as a narrow liquid crystal temperature range, but -CH ₂ CH ₂ OCO- and -COOCH ₂ CH ₂ -are polymerized as photoinitiators. The two points that the solubility in the liquid crystalline material and the property as the liquid crystal are not impaired can be achieved at a high level. In addition, in order to adjust the sensitivity wavelength range as a photoinitiator, which is an important characteristic, the absorption wavelength in consideration of the entire ring A, ring B, linking group Y ¹ and linking group Y ² from the benzene ring substituted with a carbonyl group Need to design. At this time, as Y ¹ and Y ^2, at least one _{-CH 2 CH 2 OCO -, -} CH 2 CH 2 COO -, - COOCH 2 CH 2 -, - OCOCH 2 CH 2 - I'm introducing, electronic There is also an advantage that the conjugate range can be set easily. For example, even when the sensitivity wavelength range when the aromatic ring to ring A will extend to the visible light region, -CH ₂ CH ₂ OCO as _{^{Y 1 -, - CH 2 CH}} 2 COO -, - COOCH 2 CH 2 -, If -OCOCH ₂ CH ₂ -is introduced, the conjugated structure from the benzene ring substituted with a carbonyl group can be limited to ring B, and the sensitivity wavelength range can be limited to the ultraviolet region. This also has an advantage in molecular design that it is easy to introduce an inexpensive aromatic ring such as a benzene ring into ring A.

  The photoinitiator of the present invention is excellent in solubility in the polymerizable liquid crystal material. Therefore, when the initiator of the present invention is dissolved in the polymerizable liquid crystal material, heating is minimized, so that inadvertent induction of thermal polymerization can be suppressed. Moreover, since the photoinitiator does not precipitate for a long time in a state where the photoinitiator of the present invention is added to the polymerizable liquid crystal material, the storage stability is excellent. Since radicals are efficiently generated by ultraviolet rays, the amount added to the polymerizable liquid crystal material can be minimized. Furthermore, since it has a liquid crystal skeleton, it does not impair the properties as a polymerizable liquid crystal material, so it is very useful as a photoinitiator in the production of optical anisotropic bodies and liquid crystal devices using the polymerizable liquid crystal material. Useful for.

An example of the present invention will be described below. The photoinitiator represented by the general formula (I) of the photoinitiator of the present invention preferably has the following structure. When R ¹ represents a hydrocarbon group, the number of carbon atoms in the group is preferably 2 to 12 and more preferably 3 to 8 from the viewpoint of compatibility with the polymerizable liquid crystal material. When R ¹ represents —SiR _a R _b —, R _a and R _b are each independently preferably a hydrogen atom or an alkyl having 1 to 2 carbon atoms. R ¹ preferably represents P-Sp-X. In this case, the reactive functional group P is preferably an acryloyloxy group or a methacryloyloxy group, and the spacer group Sp is an alkylene group having 3 to 8 carbon atoms. X is preferably —O—, —COO—, —OCO—, an OCOO— group or a single bond, and more preferably —O—. R ² and R ³ are preferably each independently an alkyl group having 1 to 4 carbon atoms. R ⁴ and R ⁵ are preferably each independently an alkyl group having 1 to 4 carbon atoms. More preferably, R ⁴ and R ⁵ are adjacent nitrogen atoms, and R ⁴ and R ⁵ each represent a cyclic structure, in which case the cyclic structure represents a substituted or unsubstituted aromatic ring or alicyclic ring, and these rings are Although it may be substituted with a heteroatom, among these, the formula (Ia) is particularly preferable as —NR ⁴ R ⁵ .

A and B are each independently () 1,4-phenylene group, 1,4-cyclohexylene group, decahydronaphthalene-2,6-diyl group, 1,2,3,4-tetrahydronaphthalene-2, A 6-diyl group, a 2,6-naphthylene group or a fluorene 2,7-diyl group is preferred, and a 1,4-phenylene group, a 1,4-cyclohexylene group and a fluorene 2,7-diyl group are more preferred. Y ¹ and Y ² at least one _{-CH 2 CH 2 OCO -, -} CH 2 CH 2 COO -, - COOCH 2 CH 2 - or -OCOCH ₂ CH ₂ - with the exception of, Y ¹ and Y ² are each independently In particular, a single bond, —COO— or —OCO— is preferable. From the viewpoint of imparting liquid crystal properties and suppressing volatility, n is preferably 1 or 2, and n is more preferably 1 in view of compatibility.
More specifically, examples of the photoinitiator represented by the general formula (I) include compounds represented by the following general formula (I-1) to general formula (I-34).

(In the formula, m represents an integer of 1 to 20, and a represents 0 or 1.)
Among these compounds, the general formula (I-3) includes the viewpoints of imparting compatibility with polymerizable liquid crystal materials and properties as liquid crystals, and the viewpoint of adjusting the volatility suppression / absorption wavelength region to the ultraviolet region. , (I-13), (I-14), (I-17), (I-20), (I-21), (I-27), (I-28), (I-29), ( I-30), (I-33) or (I-34) are preferred, and in view of having a reactive functional group as a photoinitiator, the compounds represented by the general formulas (I-3) and (I-17) , (I-27) or (I-30) is preferred. Further, as disclosed in Adv. Mater. 11, 573 (1999) and Special Table 2005-513241, when the use as a dichroic initiator is important, the general formulas (I-17), (I-18 ), (I-19), (I-20) or (I-21) is preferred, and general formula (I-17) or (I-20) is more preferred.

  The compound of the present invention can be synthesized by a technique used in ordinary organic synthesis. For example, the following synthesis examples can be given.

(In the formula, R ¹ , Y ¹ , A and B have the same meaning as in general formula (I).)
A phenethyl alcohol derivative of the formula (S-4) and a 2-bromoisobutyryl bromide of the formula (S-2) are subjected to Friedel-Crafts reaction and then reacted with morpholine to obtain a phenethyl alcohol derivative of the formula (S-4). The compound of the present invention represented by the general formula (S-6) can be obtained by reacting the carboxylic acid derivative of the formula (S-4) with the carboxylic acid derivative of the general formula (S-5) using a condensing agent such as dicyclohexylcarbodiimide. it can.
The following synthesis examples can also be given.

(In the formula, R ¹ , Y ¹ , A and B have the same meaning as in general formula (I).)
After the Friedel-Crafts reaction between 4-phenylbenzoic acid of formula (S-7) and isobutyryl chloride of formula (S-8), the alpha hydrogen of the carbonyl group is replaced by bromine and further reacted with morpholine To obtain a benzoic acid derivative of formula (S-10). The compound of the present invention represented by the general formula (S-12) can be obtained by reacting the alcohol derivative of the formula (S-10) and the general (S-11) with a condensing agent such as dicyclohexylcarbodiimide. .

  Next, the polymerizable liquid crystal composition of the present invention will be described. The polymerizable liquid crystal composition of the present invention is preferably prepared so as to exhibit a smectic A phase or a nematic phase at room temperature. Specifically, it is preferable that the smectic A phase or the nematic phase is maintained even at 35 ° C. or lower, preferably 30 ° C. or lower, more preferably 25 ° C. or lower. The polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition of the present invention preferably has an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group. As the polymerizable liquid crystal compound, those having two or more polymerizable functional groups in the molecule are preferable. Such bifunctional or higher functional compounds include those represented by the general formula (II)

Wherein W ¹ and W ² each independently represent a single bond, —O—, —COO— or —OCO—, and Y ³ and Y ⁴ each independently represent —COO— or —OCO—. , R and s each independently represent an integer of 2 to 18, and the hydrogen atoms of the three kinds of 1,4-phenylene groups present in the formula are alkyl groups having 1 to 7 carbon atoms, 7 or more, which may be substituted with one or more alkoxy groups, alkanoyl groups having 1 to 7 carbon atoms, cyano groups or halogen atoms). Among the compounds represented by the general formula (II), compounds represented by the general formula (II-1) to the general formula (II-8) are particularly preferable.

(In the formula, r and s each independently have the same meaning as in general formula (II).)
In General Formula (II-1) to General Formula (II-8), r and s are each independently preferably an integer of 3 to 6.
In addition, the general formula (III)

（式中、Ｗ^３及びＷ^４はそれぞれ独立的に単結合、−Ｏ−、−ＣＯＯ−又は−ＯＣＯ−を表し、Ｙ⁵は−ＣＯＯ−又は−ＯＣＯ−を表し、ｐ及びｑはそれぞれ独立的に２〜１８の整数を表し、式中に存在する３種の１，４−フェニレン基の水素原子はそれぞれ独立的に、炭素原子数１〜７のアルキル基、炭素原子数１〜７のアルコキシ基、炭素原子数１〜７のアルカノイル基、シアノ基又はハロゲン原子で一つ以上置換されていても良い。）で表される化合物も好ましい。 一般式（III）で表される化合物の中でも、一般式（III-1）〜一般式（III-8）で表される化合物が特に好ましい。

Wherein W ³ and W ⁴ each independently represent a single bond, —O—, —COO— or —OCO—, Y ⁵ represents —COO— or —OCO—, and p and q are each independently Each of the three kinds of 1,4-phenylene groups present in the formula independently represents an alkyl group having 1 to 7 carbon atoms, or 1 to 7 carbon atoms. A compound represented by an alkoxy group, an alkanoyl group having 1 to 7 carbon atoms, a cyano group, or a halogen atom may be substituted. Among the compounds represented by the general formula (III), compounds represented by the general formula (III-1) to the general formula (III-8) are particularly preferable.

(In the formula, p and q each independently represent the same meaning as in general formula (III).)
Among these compounds, they are represented by the general formula (III-2), (III-5), (III-6), (III-9) or (III-10) from the viewpoint of heat resistance and durability. Compounds are preferred, and compounds of general formula (III-2) are particularly preferred.

  In addition, as the polymerizable liquid crystal compound having two or more polymerizable functional groups in the molecule, compounds represented by general formulas (a-1) to (a-10) can be contained.

(In the formula, u and v each independently represents an integer of 2 to 18.)
Among these, the use of the compound of the general formula (a-2) or (a-3) is preferable. In General Formula (a-1) to General Formula (a-10), u and v are each independently preferably 3 to 18, more preferably 4 to 16, and particularly preferably 6 to 12.
Furthermore, for the purpose of adjusting the liquid crystal temperature range and birefringence, and reducing viscosity, the general formula (IV)

(In the formula, e represents an integer of 0 to 18, f represents 0 when e is 0 or 1, f represents 0 or 1 when e is 2 to 18, and i represents an integer of 0 to 2. C, D and E are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3 -Dioxane-2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo (2,2,2) octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2 , 5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene -2,7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene 2,7-diyl group or fluorene 2,7 -Diyl group, the 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene 2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9 , 10a-Octahydrophenanthrene 2,7-diyl group and fluorene 2,7-diyl group are unsubstituted or substituted with one or more F, Cl, CF ₃ , OCF ₃ or CH ₃ as substituents Y ⁶ and Y ⁷ are each independently a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ CH _2- , -CH ₂ CH ₂ CH ₂ O-, -OCH ₂ CH ₂ CH _2- , -CH ₂ O-, -OCH _2- , -CF ₂ O-,- OCF _2- , -CH = NN = CH-, -CF = CF-, -CH = CH-, -CH ₂ CH ₂ CH = CH-, -CH = CHCH ₂ CH _2- , -CH ₂ CH = CHCH ₂ -, -CH = CHCOO-, -OCOCH = CH-, -CH ₂ CH ₂ OCO- or -COOCH ₂ CH _2- , wherein Y ⁸ is a single bond, -O-, -CO-, -COO-,- _{OCO -, - CH 2 -,} - CH 2 O -, - OCH 2 -, - CONH -, - NHCO -, - CH 2 COO- or an -CH ₂ OCO-, Z is from 1 to 18 carbon atoms Alkyl group, carbon atom 2-18 alkenyl group, a halogen atom, CN or NCS, 1, or two or more F or as a substituent the alkyl group or alkenyl group is unsubstituted, Cl, CN, CH ₃ or CF ₃ One or more CH ₂ groups present in the alkyl group or alkenyl group may be substituted with O, CO or COO, assuming that the O atoms are not directly bonded to each other. Good. It is also possible to add a monofunctional polymerizable liquid crystal compound represented by The amount added is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 15% by mass or less. Among the compounds represented by the general formula (IV), compounds represented by the general formula (IV-1) to the general formula (IV-11) are particularly preferable.

(In the formula, e and f each independently represent the same meaning as in general formula (IV), and R represents an alkyl group having 1 to 12 carbon atoms or an alkenyl group having 2 to 12 carbon atoms.)
Furthermore, the polymerizable liquid crystal composition of the present invention may be added with a compound having a polymerizable functional group and not exhibiting liquid crystallinity. Such a compound can be used without particular limitation as long as it is generally recognized as a polymer-forming monomer or polymer-forming oligomer in this technical field. It is necessary to adjust to exhibit sex.

  The concentration of the photoinitiator of the present invention in the polymerizable liquid crystal composition of the present invention is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and particularly preferably 0.4 to 3% by mass. In addition to the photoinitiator of the present invention, other photoinitiators can be added. Examples of the photoinitiator include benzoin ethers, benzophenones, acetophenones, benzyl ketals, and acylphosphine oxides.

  In addition, a stabilizer can be added to the polymerizable liquid crystal composition of the present invention in order to improve its storage stability. Examples of the stabilizer that can be used include hydroquinone, hydroquinone monoalkyl ethers, tert-butylcatechols, pyrogallols, thiophenols, nitro compounds, β-naphthylamines, β-naphthols, and nitroso compounds. . When the stabilizer is used, the amount added is preferably 0.005 to 1% by mass, more preferably 0.02 to 0.5% by mass, and 0.03 to 0.1% by mass with respect to the liquid crystal composition. % Is particularly preferred.

  In addition, when the polymerizable liquid crystal composition of the present invention is used for a raw material of a polarizing film or an alignment film, a printing ink, a paint, a protective film or the like, a metal, a metal complex, a dye, or a pigment depending on the purpose. , Dyes, fluorescent materials, phosphorescent materials, surfactants, leveling agents, thixotropic agents, gelling agents, polysaccharides, ultraviolet absorbers, infrared absorbers, antioxidants, ion exchange resins, metal oxides such as titanium oxide, etc. Can also be added.

  Next, the polymer of the present invention will be described. The polymer produced by polymerizing the polymerizable liquid crystal composition of the present invention can be used for various applications. For example, when the polymerizable liquid crystal composition of the present invention is polymerized without being oriented, it can be used as a light scattering plate, a depolarizing plate, or a moire fringe prevention plate. In addition, a polymer produced by polymerizing the polymerizable liquid crystal composition of the present invention in an oriented state has anisotropy in physical properties and is useful. Such a polymer is, for example, a substrate obtained by rubbing the surface of the polymerizable liquid crystal composition of the present invention with a cloth or the like, or a substrate obtained by rubbing the surface of a substrate on which an organic thin film has been formed with a cloth or the like. It can be manufactured by polymerizing the liquid crystal of the present invention after it is supported on a substrate having a deposited alignment film or sandwiched between substrates.

  Examples of the method for supporting the polymerizable liquid crystal composition on the substrate include spin coating, die coating, extrusion coating, roll coating, wire bar coating, gravure coating, spray coating, dipping, and printing. . In coating, an organic solvent may be added to the polymerizable liquid crystal composition. Examples of the organic solvent include ethyl acetate, tetrahydrofuran, toluene, hexane, methanol, ethanol, dimethylformamide, methylene chloride, isopropanol, acetone, methyl ethyl ketone, acetonitrile, and cellosolves. These may be used alone or in combination, and may be appropriately selected in consideration of the vapor pressure and the solubility of the polymerizable liquid crystal composition. The amount added is preferably 90% by weight or less. As a method for volatilizing the added organic solvent, natural drying, heat drying, reduced pressure drying, or reduced pressure heat drying can be used. In order to further improve the applicability of the polymerizable liquid crystal material, it is also effective to provide an intermediate layer such as a polyimide thin film on the substrate or to add a leveling agent to the polymerizable liquid crystal material. Providing an intermediate layer such as a polyimide thin film on the substrate is also effective as means for improving the adhesion when the polymer obtained by polymerizing the polymerizable liquid crystal material and the substrate are not good in adhesion.

  Examples of a method for sandwiching the polymerizable liquid crystal composition between the substrates include an injection method using a capillary phenomenon. It is also effective to depressurize the space formed between the substrates and then inject a polymerizable liquid crystal material.

  Examples of the alignment treatment other than the rubbing treatment or the oblique vapor deposition of SiO 2 include the use of flow alignment of a liquid crystal material and the use of an electric field or a magnetic field. These orientation means may be used alone or in combination. Furthermore, a photo-alignment method can be used as an alignment treatment method instead of rubbing. This method can be applied to, for example, an organic thin film having a functional group that undergoes photodimerization reaction in a molecule such as polyvinyl cinnamate, an organic thin film having a functional group that is isomerized by light, or an organic thin film such as polyimide. An alignment film is formed by irradiating polarized ultraviolet rays. By applying an optical mask to this photo-alignment method, the patterning of the alignment can be easily achieved, so that the molecular orientation inside the polymer can be precisely controlled.

  As a shape of the substrate, in addition to a flat plate, a curved surface may be included as a constituent part. The material which comprises a board | substrate can be used regardless of an organic material and an inorganic material. Examples of the organic material used as the substrate material include polyethylene terephthalate, polycarbonate, polyimide, polyamide, polymethyl methacrylate, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyarylate, polysulfone, and triacetyl. Cellulose, cellulose, polyether ether ketone and the like can be mentioned, and examples of the inorganic material include silicon, glass, calcite and the like.

  When appropriate orientation cannot be obtained by rubbing these substrates with a cloth or the like, an organic thin film such as a polyimide thin film or a polyvinyl alcohol thin film is formed on the substrate surface according to a known method, and this is rubbed with a cloth or the like. Also good. In addition, the polyimide thin film that provides a pretilt angle used in a normal twisted nematic (TN) element or a super twisted nematic (STN) element can control the molecular orientation structure inside the polymer more precisely. Are particularly preferred.

  Further, when the orientation state is controlled by an electric field, a substrate having an electrode layer is used. In this case, it is preferable to form an organic thin film such as the aforementioned polyimide thin film on the electrode.

As a method of polymerizing the polymerizable liquid crystal composition of the present invention, since rapid progress of polymerization is desirable, a method of polymerizing by irradiating active energy rays such as ultraviolet rays or electron beams is preferable. When ultraviolet rays are used, a polarized light source or a non-polarized light source may be used. In the case where the polymerization is carried out with the liquid crystal composition sandwiched between two substrates, at least the substrate on the irradiation surface side must be given appropriate transparency to the active energy rays. In addition, after polymerizing only a specific part using a mask at the time of light irradiation, the orientation state of the unpolymerized part is changed by changing conditions such as electric field, magnetic field or temperature, and further active energy rays are irradiated. Then, it is possible to use a means for polymerization. Moreover, it is preferable that the temperature at the time of irradiation is in the temperature range in which the liquid crystal state of the polymerizable liquid crystal composition of the present invention is maintained. In particular, in the case of producing a polymer by photopolymerization, the polymerization is carried out at a temperature as close to room temperature as possible from the viewpoint of avoiding unintentional induction of thermal polymerization, that is, typically at a temperature of 25 ° C. Is preferred. The intensity of the active energy ray is preferably 0.1 mW / cm ^{2 to 2} W / cm ² . When the intensity is 0.1 mW / cm ² or less, a great amount of time is required to complete the photopolymerization and the productivity is deteriorated. When the intensity is 2 W / cm ² or more, the polymerizable liquid crystal compound or the polymerizable liquid crystal is used. There is a risk that the composition will deteriorate.

  The polymer of the present invention obtained by polymerization can be subjected to heat treatment for the purpose of reducing initial characteristic changes and achieving stable characteristic expression. The heat treatment temperature is preferably in the range of 50 to 250 ° C., and the heat treatment time is preferably in the range of 30 seconds to 12 hours.

  The polymer of the present invention produced by such a method may be peeled off from the substrate and used alone or without peeling. Further, the obtained polymer may be laminated or bonded to another substrate for use.

EXAMPLES Hereinafter, although an Example is given and this invention is further explained in full detail, this invention is not limited to these Examples. Further, “%” in the compositions of the following Examples and Comparative Examples means “% by mass”.
Example 1
Synthesis Example of Photoinitiator A mixture of hexane 475 ml, 6-chloro-1-hexanol 63.2 g, hydroquinone 0.5 g, and p-toluenesulfonic acid 4.4 g was refluxed for 6 hours while distilling off water. After cooling to room temperature, 300 ml of THF was added, and the mixture was washed with a saturated aqueous sodium hydrogen carbonate solution and then with a saturated aqueous sodium chloride solution. After the organic layer was washed with water, the organic solvent was distilled off under reduced pressure to obtain the formula (1)

の粗生成物を100g得た。

100 g of a crude product was obtained.

  A mixture of 200 g of 2- (4-hydroxyphenyl) ethyl alcohol, 44 g of the compound of formula (1), 32 g of potassium carbonate, 0.4 g of 2,4-di-tertbutylphenol, and 200 ml of DMF was stirred with heating at 80 ° C. for 16 hours. After cooling to room temperature, the organic layer is washed with dilute hydrochloric acid aqueous solution and saturated aqueous sodium chloride solution, and then the organic solvent is distilled off under reduced pressure to obtain the formula (2)

の粗生成物6gを得た。得られた粗生成物をシリカゲルカラムクロマトグラフィーにより精製し、式（2）の精製物を4.0g得た。

6 g of a crude product was obtained. The obtained crude product was purified by silica gel column chromatography to obtain 4.0 g of a purified product of formula (2).

  After pouring into 30.0 g of aluminum chloride in 50 ml of dichloromethane and cooling to −10 ° C., 20 g of 4-phenylbenzoic acid dissolved in 100 ml of dichloromethane was added dropwise with stirring while keeping the temperature of the reaction solution at 0 ° C. or lower. Further, 12 g of isobutyryl chloride dissolved in 50 ml of dichloromethane was added dropwise while keeping the temperature of the reaction solution at 0 ° C. or lower. The temperature of the reaction solution was brought to room temperature and stirred for 5 hours. The reaction solution was gently added to a mixture of 500 g of ice and 300 ml of 10% aqueous hydrochloric acid and stirred. After washing the organic layer with a saturated aqueous sodium chloride solution, the organic solvent was distilled off under reduced pressure to obtain the formula (3)

の粗生成物を13g得た。得られた粗生成物をシリカゲルカラムクロマトグラフィーにより精製し、式（３）の精製物7.0gを得た。

13 g of a crude product was obtained. The resulting crude product was purified by silica gel column chromatography to obtain 7.0 g of a purified product of formula (3).

  A mixture of 6.5 g of the compound of formula (3) and 50 ml of dichloromethane was cooled to 10 ° C. with stirring, and then 6 g of bromine was added dropwise over 5 minutes with stirring. After completion of the dropwise addition, the temperature of the reaction solution was brought to room temperature and stirred for 10 hours. The reaction solution is washed with a saturated aqueous sodium hydrogensulfite solution and a saturated aqueous sodium chloride solution, and the organic solvent is distilled off under reduced pressure to obtain the formula (4)

の粗生成物を6.2g得た。得られた粗生成物をシリカゲルカラムクロマトグラフィーにより精製し、式（４）の精製物4.7gを得た。
式（４）の化合物4.5g、モルホリン50gの混合物を16時間110℃に保ちながら撹拌した。室温まで冷却後、水を500ml加え、有機層を飽和塩化ナトリウム水溶液で洗浄後、有機溶媒を減圧留去して本発明の式（５）

6.2 g of crude product was obtained. The obtained crude product was purified by silica gel column chromatography to obtain 4.7 g of a purified product of formula (4).
A mixture of 4.5 g of the compound of formula (4) and 50 g of morpholine was stirred while maintaining at 110 ° C. for 16 hours. After cooling to room temperature, 500 ml of water is added, the organic layer is washed with a saturated aqueous sodium chloride solution, and the organic solvent is distilled off under reduced pressure to obtain the formula (5)

の粗生成物3.9gを得た。得られた粗精製物をシリカゲルカラムクロマトグラフィーにより精製し、式（５）の精製物2.5gを得た。
ジクロロメタン50mlに、式（２）の化合物2.0g、ジメチルアミノピリジン0.1g、式（4）の化合物2.2g、ジシクロヘキシルカルボジイミド1.7gを加えて室温で8時間撹拌した。有機層を希塩酸水溶液、飽和塩化ナトリウム水溶液で洗浄後、有機溶媒を減圧留去して本発明の式（6）

3.9 g of crude product was obtained. The obtained crude product was purified by silica gel column chromatography to obtain 2.5 g of the purified product of formula (5).
To 50 ml of dichloromethane, 2.0 g of the compound of the formula (2), 0.1 g of dimethylaminopyridine, 2.2 g of the compound of the formula (4) and 1.7 g of dicyclohexylcarbodiimide were added and stirred at room temperature for 8 hours. The organic layer is washed with dilute hydrochloric acid aqueous solution and saturated sodium chloride aqueous solution, and then the organic solvent is distilled off under reduced pressure to obtain the formula (6) of the present invention.

の粗生成物2.5gを得た。得られた粗精製物をシリカゲルカラムクロマトグラフィーにより精製し、式（６）の精製物1.6gを得た。
1H-NMR（400MHz、CDCl₃）：δ１．３０〜１．６５（ｍ、１４Ｈ）、２．４１（ｔ、４Ｈ）、３．０１（ｔ、２Ｈ）、３．７２（ｔ、４Ｈ）、３．９７（ｔ、２Ｈ）、４．１５（ｔ、２Ｈ）、４．６４（ｔ、２Ｈ）、５．８４（ｔ、１Ｈ）、６．１３（ｄｄ、２Ｈ）、６．３８（ｄ、２Ｈ）、６．８０〜７．９５（ｍ、１２Ｈ）
（実施例２）
以下に示す組成の重合性液晶組成物（A）を調製した。

2.5 g of crude product was obtained. The obtained crude product was purified by silica gel column chromatography to obtain 1.6 g of the purified product of formula (6).
1H-NMR (400 MHz, CDCl ₃ ): δ 1.30 to 1.65 (m, 14H), 2.41 (t, 4H), 3.01 (t, 2H), 3.72 (t, 4H), 3.97 (t, 2H), 4.15 (t, 2H), 4.64 (t, 2H), 5.84 (t, 1H), 6.13 (dd, 2H), 6.38 (d 2H), 6.80-7.95 (m, 12H)
(Example 2)
A polymerizable liquid crystal composition (A) having the following composition was prepared.

The polymerizable liquid crystal composition (A) exhibited a nematic liquid crystal phase at room temperature. The nematic-isotropic liquid phase transition temperature (TNI) was 56 ° C. The extraordinary light refractive index ne at a wavelength of 589 nm was 1.664, the ordinary light refractive index no was 1.505, and the refractive index anisotropy was 0.159. A polymerizable liquid crystal composition (B) was prepared by adding 1% of the photoinitiator of the formula (6) of the present invention thereto. The temperature required to completely dissolve the initiator of formula (6) in the polymerizable liquid crystal composition (A) was 48 ° C. The TNI of the polymerizable liquid crystal composition (B) was 57 ° C., ne at a wavelength of 589 nm was 1.665, no was 1.506, and the refractive index anisotropy was 0.159. This polymerizable liquid crystal composition was injected into a homogeneous alignment cell having a length of 5 cm, a width of 5 cm, and a gap of 5 μm by a heating vacuum injection method (temperature 80 ° C., reduced pressure to 133 Pa for 30 minutes). After cooling to 25 ° C., it was confirmed that the polymerizable liquid crystal composition (B) was homogeneously aligned. When this was irradiated with ultraviolet light of 4 mW / cm ² for 120 seconds using a high-pressure mercury lamp, it was confirmed that the polymerizable liquid crystal composition (B) was cured and polymerized while maintaining a uniform alignment state. .

(Comparative Example 1)
The polymerizable liquid crystal composition (A) prepared in Example 2 was added to the photoinitiator Irgacure 651 (Ciba Specialty Chemicals) of formula (11).

Was added in an amount of 1% to prepare a polymerizable liquid crystal composition (C). The temperature required to completely dissolve Irgacure 651 in the polymerizable liquid crystal composition (A) was 66 ° C. The TNI of the polymerizable liquid crystal composition (C) was 52 ° C., ne at a wavelength of 589 nm was 1.660, no was 1.508, and the refractive index anisotropy was 0.152. This polymerizable liquid crystal composition was injected into a homogeneous alignment cell having a length of 5 cm, a width of 5 cm, and a gap of 5 μm by a heating vacuum injection method (temperature 80 ° C., reduced pressure to 133 Pa for 30 minutes). After cooling to 25 ° C., it was confirmed that the polymerizable liquid crystal composition (C) was homogeneously aligned. This was irradiated with ultraviolet rays of 4 mW / cm 2 for 120 seconds using a high-pressure mercury lamp, but the polymerizable liquid crystal composition (C) did not polymerize. As a result of investigating the cause, it was found that Irgacure 651 was almost volatilized during the vacuum injection.

From the comparison between Example 2 and Comparative Example 1, the photoinitiator of the present invention has a lower heating temperature than that of a normal photoinitiator when dissolved in the polymerizable liquid crystal material, and is compatible with the polymerizable liquid crystal material. Is high. Further, the addition of the initiator of the present invention does not lower the nematic-isotropic liquid phase transition temperature and birefringence of the polymerizable liquid crystal material, whereas the addition of a normal photoinitiator allows the polymerizable liquid crystal material to be reduced. This lowers the nematic-isotropic liquid phase transition temperature and birefringence. That is, it can be seen that even when the photoinitiator of the present invention is added, there is no tendency to impair the properties of the polymerizable liquid crystal material as a liquid crystal. Furthermore, it turns out that the photoinitiator of this invention is hard to volatilize even if a vacuum injection method is applied.
(Example 3)
A polymerizable liquid crystal composition (D) having the following composition was prepared. When the polymerizable liquid crystal composition (D) was once heated to an isotropic liquid phase and then cooled, it changed into a nematic phase at 72 ° C. This nematic phase was maintained even at room temperature.

The polymerizable liquid crystal composition (E) of the present invention was prepared by adding 5% of the photoinitiator of the formula (6) of the present invention to the polymerizable liquid crystal composition (D). The temperature required to completely dissolve the initiator of formula (6) in the polymerizable liquid crystal composition (D) was 50 ° C. This polymerizable liquid crystal composition (E) is dissolved in a 1: 1 (volume ratio) solvent mixture of cyclohexane, propylene glycol monomethyl ether and cyclohexane to prepare a coating solution (F). did. This coating solution was spin-coated (3000 rpm, 15 seconds) on a 5 cm square glass substrate with a polyimide alignment film. This was depressurized at a temperature of 80 ° C. and 133 Pa for 20 minutes to volatilize the solvent. After cooling to room temperature in air, it was allowed to stand for 30 minutes, but no crystal precipitation of the photoinitiator of the present invention was observed. When it was irradiated with ultraviolet rays of 20 mW / cm ² in air for 300 seconds using a high-pressure mercury lamp, it was confirmed that it cured.
(Comparative Example 2)
The polymerizable liquid crystal composition (D) prepared in Example 3 was added to the photoinitiator of formula (12).

Was added in an amount of 5% to prepare a polymerizable liquid crystal composition (G). The temperature required to completely dissolve the initiator of the formula (12) in the polymerizable liquid crystal composition (D) was 89 ° C. This polymerizable liquid crystal composition (G) is dissolved in a 1: 1 (volume ratio) solvent mixture of cyclohexane, propylene glycol monomethyl ether and cyclohexane to prepare a coating solution (H). did. This coating solution was spin-coated (3000 rpm, 15 seconds) on a 5 cm square glass substrate with a polyimide alignment film. This was depressurized at a temperature of 80 ° C. and 133 Pa for 20 minutes to volatilize the solvent. After cooling to room temperature in air and leaving to stand for 30 minutes, crystal precipitation of the photoinitiator of formula (12) was partially observed. When irradiated with 20 mW / cm ² of UV light in air for 300 seconds using a high-pressure mercury lamp, it was confirmed that the portions other than the crystal precipitation portion were cured.

From the comparison between Example 3 and Comparative Example 2, the photoinitiator of the present invention has higher compatibility with the polymerizable liquid crystal material than the photoinitiator having almost the same chemical structure and the almost same molecular weight. When dissolved in the polymerizable liquid crystal material, the heating temperature can be low, and inadvertent induction of thermal polymerization of the polymerizable liquid crystal material can be suppressed. Moreover, since crystal precipitation of the photoinitiator can be suppressed, a uniform optical anisotropic body can be obtained.

Claims (4)

Formula (I)

(In the formula, R ¹ represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group may be substituted with a halogen atom or a cyano group, and is not adjacent to —CH ₂ —. Represents —O—, —S—, —NH—, —NR ₀ —, (R ₀ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), in which oxygen atoms or sulfur atoms are not directly bonded to each other. .)-SiR _a R _b- , (R _a and R _b each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms) -CO-, -COO-, -OCO-, OCOO- , -SCO-, -COS-, -CH = CH- or -C≡C- may be substituted, R ¹ also represents P-Sp-X-, where P represents a reactive functional group , Sp represents a spacer group or a single bond, X represents -O-, -S-, -CO-, -COO-, -OCO-, OCOO-, -SCO-, -COS-, -CH = CH-, -C≡C-, -CH = CHCOO-, -OOCCH = CH- or a single bond.) R ² and R ³ each independently represent a hydrocarbon group having 1 to 20 carbon atoms, R ⁴ and R ⁵ Each independently represents a hydrocarbon group having 1 to 20 carbon atoms, or -NR ⁴ R ⁵ represents a substituted or unsubstituted aromatic ring or alicyclic ring, and these rings may be substituted with a heteroatom. A and B are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane- 2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo (2,2,2) octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5- Diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2, 7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene 2,7-diyl group or fluorene 2,7-diyl group The table The 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7-diyl group, 9,10-dihydrophenanthrene- 2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene 2,7-diyl group and fluorene 2,7-diyl group are unsubstituted or have one substituent Or two or more F, Cl, CF ₃ , OCF ₃ or CH ₃ , wherein Y ¹ and Y ² are each independently a single bond, —COO—, —OCO—, —CH═N— , -N = CH-, -C≡C-, -CH ₂ CH _2- , -CH ₂ CH ₂ CH ₂ CH _2- , -CH ₂ CH ₂ CH ₂ O-, -OCH ₂ CH ₂ CH _2- , -CH ₂ O-, -OCH _2- , -CF ₂ O-, -OCF _2- , -CH = NN = CH-, -CF = CF-, -CH = CH-, -CH ₂ CH ₂ CH = CH -, -CH = CHCH ₂ CH _2- , -CH ₂ CH = CHCH _2- , -CH = CHCOO-, -OCOCH = CH-, -CH ₂ CH ₂ OCO-, -CH ₂ CH ₂ COO-, -COOCH ₂ CH ₂ - or -OCOCH ₂ CH ₂ - represents a, at least one _{-CH 2 CH 2 OCO -, -} CH 2 CH 2 COO -, - COOCH 2 CH 2 - or - Represents OCOCH ₂ CH ₂ —, and n represents an integer of 0 to 2. A photoinitiator for a polymerizable liquid crystal material represented by: R ¹ represents P-Sp-X-, P represents an acryloyloxy group, and —NR ⁴ R ⁵ is represented by the formula (I-a)

The photoinitiator according to claim 1, which represents A polymerizable composition comprising the photoinitiator according to claim 1 and a polymerizable liquid crystal compound. An optical anisotropic body, which is a polymer of the polymerizable liquid crystal composition according to claim 3 .