TWI475006B - Photopolymerization initiator and photosensitive composition - Google Patents

Description

Photopolymerization initiator and photosensitive composition

The present invention relates to a novel photopolymerization initiator, a photosensitive composition containing the photopolymerization initiator, and a cured product thereof.

The photosensitive composition is widely used in a form in which a photopolymerization initiator is blended in a polymerizable compound having an olefin bond, and is used in a photoresist, a photocurable ink, a photocurable coating, a photocurable adhesive, It is put into practical use for applications such as a photosensitive resin for light shaping and a photosensitive printing plate. The photosensitive composition can be polymerized and hardened by irradiating ultraviolet light or visible light (referred to as exposure) with a mercury lamp, a xenon lamp, a laser or the like as a light source, but it is desirable to obtain a high-efficiency hardening with a small amount of exposure. A photosensitive composition of sensitivity, thus requiring a high sensitivity photopolymerization initiator.

As far as the photopolymerization initiator is concerned, many compounds have been proposed so far, such as acetophenone compounds, benzophenone compounds, benzoin ether compounds, and α-amines. Alpha-aminoalkylphenone compound, thioxanthone compound, organic peroxide, biimidazole compound, titanocene compound, three (triazine) compound, acylphosphine oxide compound, quinone compound, oxime ester compound, and the like. However, these are not intended to be sufficient.

In recent years, an oxime ester compound having a carbazole skeleton (Patent Documents 1 to 9 below) has been disclosed, and there is a report that the sensitivity system greatly exceeds that of the conventional photopolymerization initiator. However, even if the photopolymerization initiator is used, there is still a need for high performance in the use of a photoresist (black resist, RGB resist) used in the manufacture of a color filter of a liquid crystal display. It is not always possible to achieve a level of satisfaction.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-359639

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-097141

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2005-220097

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2006-160634

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2008-094770

[Patent Document 6] Japanese Patent Publication No. 2008-509967

[Patent Document 7] JP-A-2009-040762

[Patent Document 8] WO2006/018973 Booklet

[Patent Document 9] WO2008/078678

Further, the photoresist used in the production of the color filter of the liquid crystal display is generally subjected to a calcination treatment at a high temperature of about 230 ° C in the production step. At this time, the photopolymerization initiator remaining in the photoresist is thermally decomposed, and sometimes the decomposition product generated may contaminate the calciner and impair the reliability of the color filter. Therefore, it is desired to obtain a photopolymerization initiator which does not have the above-mentioned concerns and is excellent in thermal stability.

The present invention has been made in view of the problems of the prior art, and an object thereof is to provide a photopolymerization initiator having high sensitivity and excellent thermal stability, and a photosensitive composition using the photopolymerization initiator.

In order to solve the problem, the present inventors have found that a specific functional group can be introduced into an oxime ester compound having a carbazole skeleton as a photopolymerization initiator, and the object is attained.

That is, the present invention is a photopolymerization initiator represented by the following formula (1):

(R ¹ represents an aryl group having at least one nitro group as a substituent, and R ² is a saturated or unsaturated monovalent organic group having 1 to 20 carbon atoms which may have a substituent, and may also form a branch. The structure or ring structure may also have a hetero atom present at any position; and, Ar is a substituent having a carbazole skeleton having a nitro group).

Here, R ² is preferably a methyl group. Furthermore, the present invention also provides a photosensitive composition containing the above photopolymerization initiator and a polymerizable compound having an olefin bond, and a cured product obtained by curing the photosensitive composition.

Hereinafter, the present invention will be described in detail.

The photopolymerization initiator of the present invention has a structure represented by the formula (1). Here, the C=N double bond at the oxime site may have geometric isomers of the E body and the Z body, but this case does not particularly distinguish this. Therefore, the structures represented by the general formula (1) and the following formulas (2) to (13) represent a mixture of any of these geometric isomers or any of them.

In the formula (1), a preferred structure is as shown in the following formula (2):

Here, R ¹ represents an aryl group having at least one nitro group as a substituent. From the standpoint of availability, R ^{1 is} preferably a phenyl group having at least one nitro group as a substituent, for example, 2-nitrophenyl group, 3-nitrophenyl group, 4-nitrophenyl group, 2,4-dinitrophenyl, 2,5-dinitrophenyl, 2,6-dinitrophenyl, 3,4-dinitrophenyl, 3,5-dinitrophenyl, 2,3,5-trinitrophenyl, 2,4,6-trinitrophenyl, etc. are advantageous. Further, it is preferred that the hydrogen atom on the benzene ring having at least one phenyl group of the nitro group be a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like), an alkyl group (methyl group, an ethyl group, or the like). a substituted derivative such as a propyl group, a butyl group or the like, a halogenated alkyl group (trifluoromethyl group, chloromethyl group, etc.) or a cyano group, for example, a 2-halo-3-nitrophenyl group (halogen means a halogen atom) Substituents, the same as below), 2-halo-4-nitrophenyl, 2-halo-5-nitrophenyl, 2-halo-6-nitrophenyl, 3-halo-2-nitrobenzene , 3-halo-4-nitrophenyl, 3-halo-5-nitrophenyl, 5-halo-2-nitrophenyl, 4-halo-2-nitrophenyl, 4-halo- 3-nitrophenyl, 4-halo-3,5-dinitrophenyl, 2-alkyl-3-nitrophenyl, 2-alkyl-4-nitrophenyl, 2-alkyl- 5-nitrophenyl, 2-alkyl-6-nitrophenyl, 3-alkyl-2-nitrophenyl, 3-alkyl-4-nitrophenyl, 3-alkyl-5- Nitrophenyl, 5-alkyl-2-nitrophenyl, 4-alkyl-2-nitrophenyl, 4-alkyl-3-nitrophenyl, 4-alkyl-3,5- Dinitrophenyl, 2-nitro-4-(trifluoromethyl)phenyl, 3-nitro-5-(trifluoromethyl)phenyl, 4-cyano-2-nitrophenyl, 3-cyano-5-nitrophenyl . Further, R ¹ may be a polycyclic aryl group having at least one nitro group as a substituent, for example, a naphthyl group, an anthracenyl group, a phenanthryl group or the like.

In the general formulae (1) and (2), R ² and R ³ each independently represent a saturated or unsaturated monovalent organic group having 1 to 20 carbon atoms which may have a substituent, and may also form a branched structure or a ring. Structure, there may be heteroatoms in any position. Specific examples of R ² and R ³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a second butyl group, a third butyl group, a pentyl group, an isopentyl group, and a new one. Butyl, third amyl, hexyl, heptyl, octyl, 2-ethylhexyl, decyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl , icosyl, cyclopentyl, cyclohexyl, vinyl, allyl, ethynyl, phenyl, tolyl, 2,4,6-trimethylphenyl (mesityl), a saturated or unsaturated monovalent hydrocarbon group such as naphthyl, anthracenyl, phenanthryl, benzyl, 2-phenylethyl or 2-phenylvinyl, or pyridyl, piperidyl, N-piperidino, pyrrolyl, pyrrolidinyl, imidazolyl, imidazolidinyl, furyl, tetrahydrofuranyl, thienyl, tetrahydrothiophenyl, morpholinyl, A saturated or unsaturated monovalent heterocyclic group such as a morpholino or a quinolyl group. Further, a structure in which a halogen atom, a hydroxyl group, a sulfanyl group, a carbonyl group, a thiocarbonyl group, a carboxyl group, a thiocarboxy group, or a disulfide is introduced at any of the above hydrocarbon group and heterocyclic group may be mentioned. Carboxyl, carbenyl, cyano, nitro, nitroso, sulfonate, amine, imine, decyl, ether, thioether, ester, thioester, dithioester A structure in which a group, a mercapto group, a thioguanamine group, an urethane group, a thiamine group or the like is used as a substituent. Further, R ² and R ³ include not only a monovalent organic group such as a methyl group but also a monovalent organic group located on a carbon atom, and a monovalent organic group such as a methoxy group, a methylthio group or a dimethylamino group. R ² and R ³ may be appropriately selected depending on the molecular weight, sensitivity, solubility, and the like of the photopolymerization initiator of the intended purpose, and a saturated or unsaturated monovalent hydrocarbon group having 1 to 20 carbon atoms is preferred, and R ² is a The base is optimal and the R ³ -based ethyl group is most preferred.

Specific examples of the photopolymerization initiator of the present invention are shown below. However, the invention is not limited thereto.

The method for producing the photopolymerization initiator of the present invention is not particularly limited, and for example, it can be carried out in the following order. First, R ^{3 is} introduced into the 9-position of 9H-carbazole by a nucleophilic substitution reaction or the like, and then the 6 position is nitrated with nitric acid. Further, the ketone body was obtained by introducing R ¹ CO at the 3-position by Friedel-Crafts Acylation Reaction. This is converted into a hydrazine by a hydroxylamine, and then esterified with hydrazine halide or an acid anhydride of R ² COOH to obtain a photopolymerization initiator of the formula (2). In addition, the order of nitrification and Ryd-Kraft is also interchangeable.

The photosensitive composition of the present invention contains a photopolymerization initiator of the formula (1) and a polymerizable compound having an olefin bond. For the polymerizable compound having an olefin bond, a known compound used in the conventional photosensitive composition can be used without particular limitation, and in particular, acrylic acid and methacrylic acid (hereinafter, collectively referred to as "(meth)acrylic acid" or the like) Derivatives of the invention are advantageous, preferably using, for example, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate a (meth) acrylate derivative such as di(trimethylolpropane)tetra(meth)acrylate or dipentaerythritol hexa(meth)acrylate, or a bisphenol A type epoxy bis(A) Acrylate, bisphenol F type epoxy di(meth) acrylate, bisphenol quinone type epoxy bis (meth) acrylate, phenol novolac type epoxy group (methyl) A (meth)acrylic acid epoxy ester derivative such as an acrylate or a cresol novolak type epoxy group poly(meth)acrylate. Further, a reaction product of the above (meth)acrylic acid derivative and a compound having a (preferably plural) isocyanate group or an acid anhydride group in the structure is also suitable. Further, a vinyl resin (acrylic (co)polymer, methacrylic (co)polymer, maleic acid (co)polymer, styrene (co)polymer, etc.) which is a known resin may be used. , a polyester resin, a polyamide resin, a polyimide resin, a polyurethane resin, a polyether resin, or the like, which introduces (meth) propylene oxime in a main chain or a side chain by an ester bond, a guanamine bond, an amine ester bond, or the like. Base resin, etc. Further, in addition to the (meth)acrylic acid derivative, there may be mentioned, for example, a maleic acid derivative, a maleic imide derivative, a crotonic acid derivative, an itaconic acid derivative, a cinnamic acid derivative, or a vinyl derivative. A vinyl alcohol derivative, a ketene derivative, a vinyl aromatic derivative or the like. The polymerizable compound having an olefin bond may be a compound having a thermoreactive functional group such as an epoxy group or an alkali-soluble functional group such as a carboxyl group. These polymerizable compounds having an olefin bond may be used singly or in combination of plural kinds.

In the photosensitive composition of the present invention, the ratio of the photopolymerization initiator represented by the formula (1) is not particularly limited, and the photopolymerization initiator is 100 parts by weight based on 100 parts by weight of the polymerizable compound having an olefin bond. It is preferably from 0.1 to 50 parts by weight, more preferably from 1 to 20 parts by weight.

The photosensitive composition of the present invention may contain other optional components as needed, such as a coloring material, a filler, a resin, an additive, a solvent, and the like. Here, examples of the coloring material include a dye, an organic pigment, an inorganic pigment, and a carbon black pigment. Examples of the filler include silica, talc, and the like, and examples of the resin include a vinyl resin (acrylic (co)polymer, a methacrylic acid (co)polymer, a maleic acid (co)polymer, a styrene (co)polymer, etc., a polyester resin, a polyamide resin, a polyimide resin, a polyurethane resin, a polyether resin, Examples of the epoxy resin, the melamine resin, and the like include a curing agent, a crosslinking agent, a dispersing agent, a surfactant, a decane coupling agent, a viscosity adjusting agent, a wetting agent, an antifoaming agent, an antioxidant, and the like, and the solvent may, for example, be an ester. Examples of the solvent, the ketone solvent, the ether solvent, the alcohol solvent, the aromatic solvent, the aliphatic solvent, the amine solvent, the guanamine solvent, and the like. Any of the optional components can be used without any particular limitation.

Further, in the photosensitive composition of the present invention, in addition to the photopolymerization initiator represented by the formula (1), a known photopolymerization initiator or dye sensitizer may be used in combination. For example, it can be used without particular limitation: acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl Acetophenone compounds such as benzyl dimethyl ketal; benzophenone, 2,4,6-trimethylbenzophenone, 4,4'- Benzophenone compound such as bis(N,N-diethylamino)benzophenone; benzoin ethyl ether a benzoin ether compound such as benzoin tert-butyl ether; 2-methyl-1-[4-(methylthio)phenyl]-2-(N-morpholinyl) ) 2-methyl-1-[4-(methylsulfanylphenyl)-2-morpholinopropan-1-one), 2-benzyl-2-(N,N-dimethylamino)- 1-(4-(N-N-dimethylamino)-1-(4-morpholinophenyl)butan-1-one) --aminoalkyl benzophenone compound; thioxanthone compound such as thioxanthone or 2,4-diethylthioxanthone; 3,3'4,4'-four (first Tributyl carbonyl benzophenone (3,3'4,4'-tetra(tert-butylperoxycarbonyl) benzophenone) Machine peroxide; 2,2'-bis(2-chlorophenyl)-4,4'5,5'-tetraphenyl-1,2-biimidazole (2,2'-bis(2-chlorophenyl) -4,4'5,5'-tetraphenyl-1,2-biimidazole) bisimidazole compound; bis(η ⁵ -cyclopentadienyl) bis[2,6-difluoro-3-(1-pyrrolyl) a ferrocene compound such as bis(η ⁵ -cyclopentadienylbisbis[2,6-difluoro-3-(1-pyrrolyl)phenyl]titanium); 2,4,6-tris(trichloromethyl) )-1,3,5-three (2,4,6-tris(trichloromethyl)-1,3,5-triazine), 2-[3,4-(methylenedioxy)phenyl]-4,6-bis(trichloromethyl) -1,3,5-three (2-[3,4-(methylenedioxy)phenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine) Compound; (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, bis(2,4,6-trimethylbenzylidene) a fluorenylphosphine oxide compound such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; an anthracene compound such as camphorquinone; 1-[4-(phenylthio)phenyl] Octazol-1,2-dione = 2-[4-(phenylsulfanylphenyl) octane-1, 2-dione 2-O-benzoyloxime), 1-[9-ethyl -6-(2-methylbenzylidene)oxazol-3-yl]ethanone=O-acetamidopurine (1-[9-ethyl-6-(2-methylbenzoyl)carbazol-3-y1]ethanone An oxime ester compound such as -O-acetyloxime.

The method for producing the cured product of the photosensitive composition of the present invention can be carried out by a known method, as long as the photosensitive composition is coated or injected into a suitable substrate or mold for the purpose of blending or use, and then cured by exposure. . Here, development is further performed by selective exposure using a photomask or the like, that is, processing such as image formation and shape formation. Further, treatment such as calcination may be performed as needed.

The photopolymerization initiator of the present invention is extremely useful because it can provide a photosensitive composition having excellent sensitivity and high sensitivity which can be efficiently cured with a small amount of exposure. When the photopolymerization initiator of the present invention efficiently absorbs ultraviolet light and visible light to be in an excited state, the oxime ester bond is rapidly broken to form a highly reactive radical species, and the photosensitive composition is contained therein. The polymerizable compound having an olefin is polymerized at a high speed. Further, since the photopolymerization initiator of the present invention is excellent in thermal stability, it is subjected to a calcination treatment at a high temperature of about 230 ° C in the production step, even in the case of a photoresist used for the production of a color filter of a liquid crystal display. There is also no decomposition of the residual photopolymerization initiator to cause damage to the reliability of the color filter.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[Example 1] <(9-Ethyl-6-nitrooxazol-3-yl)(4-nitrophenyl)methanone=O-acetamidoxime>(Photopolymerization initiator of formula (3)) (Synthesis of photopolymerization initiator)

The above photopolymerization initiator was synthesized by the reaction of the four steps below. The reaction was carried out using a glass reactor under normal pressure.

Step 1: Using nitromethane as a solvent, 9-ethylcarbazole (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.10 mol, 4-nitrobenzylhydrazine chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.15 mol, and aluminum chloride 0.15 moles were reacted at 0 to 5 ° C for 6 hours. The reaction was dropped into ice water, and the precipitated solid was recovered and washed thoroughly to obtain a crude product of (9-ethyloxazol-3-yl)(4-nitrophenyl)methanone equivalent to 0.07 mol. Things.

Step 2: Using acetic acid as a solvent, the total amount of the product of Step 1 and 0.14 mol of nitric acid were reacted at 80 ° C for 6 hours. The reaction was dropped into ice water, and the precipitated solid was recovered and washed thoroughly to obtain (9-ethyl-6-nitrooxazol-3-yl) (4-nitrophenyl) equivalent to 0.06 mol. Crude product of ketone.

Step 3: Using tetrahydrofuran as a solvent, the whole amount of the product of Step 2 and 0.12 mol of hydroxylamine hydrochloride were reacted under reflux for 24 hours. After cooling, the reaction was dropped into water, and the precipitated solid was recovered and washed thoroughly to obtain (9-ethyl-6-nitrooxazol-3-yl) (4-nitrobenzene) equivalent to 0.05 mol. Methyl ketone = crude product of hydrazine.

Step 4: Using pyridine as a solvent, the whole amount of the product of Step 3 and 0.10 mol of acetic anhydride were reacted at 80 ° C for 6 hours. After cooling, the reaction was dropped into water, and the precipitated solid was recovered and thoroughly washed to obtain (9-ethyl-6-nitrooxazol-3-yl) (4-nitrobenzene) equivalent to 0.04 mol. The crude product of ketone = O-ethyl hydrazine. Further, it was refined with a rubber tube column to obtain a pure product of 0.02 mol. When the obtained pure compound was identified by ¹ H-NMR (CDCl ₃ ), the following results were shown.

δ=8.94(s,1H), 8.47(d,1H), 8.43(d,2H)8.16(s,1H), 7.96(d,1H), 7.59(d,2H),7.52(d,1H), 7.46(d,1H), 4.44(q,2H), 2.12(s,3H), 1.53(t,3H)

(Production of photosensitive composition)

Propylene glycol monomethyl ether B having 0.4% by weight of the photopolymerization initiator obtained above and an alkali-developing photosensitive resin (polymerizable compound having an olefin bond) having a bisphenol fluorene-type epoxy diacrylate structure Acid solution ("V-259ME" manufactured by Nippon Steel Chemical Co., Ltd., solid concentration: 56.5 wt%) 5.2 wt%, pentaerythritol tetraacrylate (polymerizable compound having an olefin bond) 1.0 wt%, carbon black A pigment (coloring material) obtained by dispersing a cationic polymer dispersant in propylene glycol monomethyl ether acetate (carbon black pigment concentration: 25.3% by weight, solid content concentration: 31.6 wt%), 27.7% by weight, polyfluorene Silicone surfactant ("FZ-2122" manufactured by Dow Corning Toray Co., Ltd.) 0.05% by weight, 3-(glycidoxy)propyltrimethoxydecane (decane coupling agent) 0.05% by weight, propylene glycol monomethyl The base ether acetate (solvent) (22.2% by weight) and cyclohexanone (solvent) 43.4% by weight were blended in proportion to prepare a photosensitive composition. The photosensitive composition has a solid content concentration of 13.2% by weight and a carbon black pigment concentration of 53.1% by weight in the solid content, and can be used as a photoresist (black resist) for producing a color filter of a liquid crystal display. Here, the solid content referred to herein means a component other than the solvent.

(Evaluation of photosensitive composition)

The photosensitive composition was applied onto an alkali-free glass substrate using a spin coater, and dried on a hot plate at 80 ° C for 1 minute to prepare a test piece. At this time, the coating conditions (number of rotations) were adjusted so that a cured film having a film thickness of 1.0 μm was obtained. Next, an ultraviolet ray of 100 mJ/cm ^{2 was} irradiated with an ultrahigh pressure mercury lamp having an i-ray illuminance of 30 mW/cm ² using a reticle having a transmittance of 0 to 100% in a stepwise manner, and the test piece was subjected to image exposure. Then, the test piece was treated with an alkaline developing solution (10-fold dilution of "V-2401 ID" manufactured by Nippon Steel Chemical Co., Ltd.) at 26 ° C for 1 minute, and then washed with water to visualize the image. This image can read the amount of exposure required for photohardening. Finally, the test piece was calcined in a hot air oven at 230 ° C for 30 minutes to obtain a cured film of the photosensitive composition. The amount of exposure required for photohardening determined by the image was 26 mJ/cm ² . Further, the cured film has an optical density of 4.5 μm and has high light-shielding properties.

[Embodiment 2] <(9-Hexyl-6-nitrooxazol-3-yl)(4-nitrophenyl)methanone=O-acetylindenoxime>(Photopolymerization initiator of the formula (4))

The synthesis was carried out in the same manner as in Example 1. When the obtained pure compound was identified by ¹ H-NMR (CDCl ₃ ), the following results were shown.

δ=8.92(s,1H), 8.49(d,1H), 8.47(d,2H), 8.14(s,1H), 7.96(d,1H), 7.61(d,2H), 7.48(d,1H) , 7.46 (d, 1H), 4.30 (q, 2H), 2.12 (s, 3H), 1.90-1.83 (m, 2H), 1.43-1.35 (m, 2H), 1.35-1.23 (m, 4H), 0.86 (t, 3H)

Further, in the same manner as in Example 1 was prepared and evaluated photosensitive composition, an exposure amount required for the photo-curing of 26mJ / cm ^2.

[Example 3] <(9-(2-ethylhexyl)-6-nitrooxazol-3-yl)(4-nitrophenyl)methanone=O-ethylindenyl hydrazone>(Photopolymerization of formula (5) Starting agent)

The synthesis was carried out in the same manner as in Example 1. When the obtained pure compound was identified by ¹ H-NMR (CDCl ₃ ), the following results were shown.

δ=8.93(s,1H), 8.46(d,2H), 8.41(d,1H), 8.15(s,1H), 7.95(d,1H), 7.60(d,2H), 7.48(d,1H) , 7.45 (d, 1H), 4.17 (q, 2H), 2.16 (s, 3H), 2.07 (m, 1H), 1.45-1.30 (m, 4H), 1.30-1.26 (m, 4H), 0.92 (t , 3H), 0.86 (t, 3H)

Further, a photosensitive composition was produced and evaluated in the same manner as in Example 1, and the exposure amount required for photocuring was 26 mJ/cm ² .

[Example 4] <(9-Ethyl-6-nitrooxazol-3-yl)(3-nitrophenyl)methanone=O-acetamidoxime>(Photopolymerization initiator of formula (6))

The synthesis was carried out in the same manner as in Example 1. When the obtained pure compound was identified by ¹ H-NMR (CDCl ₃ ), the following results were shown.

δ=8.94(s,1H), 8.59(s,1H), 8.54-8.50(m,2H), 8.47(d,1H), 8.43(d,1H), 8.16(s,1H), 7.96(d, 1H), 7.52 (d, 1H), 7.46 (d, 1H), 4.42 (q, 2H), 2.15 (s, 3H), 1.51 (t, 3H)

Further, a photosensitive composition was produced and evaluated in the same manner as in Example 1, and the exposure amount required for photocuring was 26 mJ/cm ² .

[Example 5] <(9-Ethyl-6-nitrooxazol-3-yl)(3,5-dinitrophenyl)methanone=O-acetamidoxime>(Photopolymerization initiator of formula (7) )

The synthesis was carried out in the same manner as in Example 1. When the obtained pure compound was identified by ¹ H-NMR (CDCl ₃ ), the following results were shown.

δ=9.29(s,1H), 8.95(m,3H), 8.43(d,1H), 8.14(s,1H), 7.93(d,1H),7.53(d,1H), 7.48(d,1H) , 4.48 (q, 2H), 2.17 (s, 3H), 1.52 (t, 3H)

Further, a photosensitive composition was produced and evaluated in the same manner as in Example 1, and the exposure amount required for photocuring was 26 mJ/cm ² .

[Comparative Example 1]

The photopolymerization initiator of Example 1 was changed to 1-(9-ethyl-6-nitrooxazol-3-yl)ethanone=O-ethylindenyl hydrazide (the following formula (14) The photosensitive composition was prepared and evaluated in the same manner as in Example 1 except for the compound. As a result, the amount of exposure required for photohardening was 30 mJ/cm ² , which showed a lower sensitivity than the example (the less the amount of exposure required for photohardening, the higher the sensitivity).

[Comparative Example 2]

The photopolymerization initiator of Example 1 was changed to (9-ethyl-6-nitrooxazol-3-yl)phenyl ketone = O-ethyl fluorenyl hydrazide (the following formula (15) The photosensitive composition was prepared and evaluated in the same manner as in Example 1 except for the compound. As a result, the amount of exposure required for photohardening was 37 mJ/cm ² , which showed a lower sensitivity than the example.

[Comparative Example 3]

The photopolymerization initiator of Example 1 was changed to (9-ethyloxazol-3-yl)(4-nitrophenyl)methanone=O-ethylindenyl hydrazide (shown by the following formula (16)) The photosensitive composition was prepared and evaluated in the same manner as in Example 1 except for the compound. As a result, the exposure amount up to 100 mJ/cm ² was completely incapable of hardening the light, and showed a lower sensitivity than the example.

[Comparative Example 4]

The photopolymerization initiator of Example 1 was changed to 1-(9-ethyl-6-(2-methylbenzylidene)oxazol-3-yl)ethanone=O-ethylindenyl hydrazide (described below) A photosensitive composition was prepared and evaluated in the same manner as in Example 1 except that the compound represented by the formula (17), "Irgacure OXE02" manufactured by BASF Corporation) was used. As a result, the amount of exposure required for photohardening was 67 mJ/cm ² , which showed a lower sensitivity than the example.

(Evaluation of thermal stability)

The thermal stability of the photopolymerization initiators of the above Examples 1, 4, and 5 and Comparative Examples 1 and 4 was evaluated by differential scanning calorimetry. The results are shown in Table 1. The decomposition starting points of the photopolymerization initiators of the examples all exceeded 230 ° C, indicating excellent thermal stability. On the other hand, the decomposition starting point of the photopolymerization initiator of the comparative example was less than 230 ° C, and the thermal stability was insufficient.

(industrial availability)

Since the photopolymerization initiator of the present invention is excellent in high sensitivity and thermal stability, it can be suitably used as a photoresist, a photocurable ink, a photocurable coating, a photocurable adhesive, a photosensitive resin for photoforming, Use for photosensitive printing plates, etc. In particular, it is most suitable for applications requiring high performance such as photoresists (black resists, RGB resists) used in the manufacture of color filters for liquid crystal displays.

Claims (4)

A photopolymerization initiator is represented by the following formula (2): However, R ¹ represents an aryl group having at least one nitro group as a substituent, and further, R ² and R ³ are each independently a saturated or unsaturated monovalent organic group having 1 to 20 carbon atoms which may have a substituent. a branched structure or a ring structure may also be formed, and a hetero atom may be present at any position; in the formula (2), only one oxime ester group is present in the molecule; however, R ³ is a phenyl group having a substituent. situation. The photopolymerization initiator according to claim 1, wherein R ² is a methyl group. A photosensitive composition comprising: a photopolymerization initiator of the first or second aspect of the patent application; and a polymerizable compound having an olefin bond. A cured product obtained by hardening a photosensitive composition of the third application of the patent application.