JP2009074007A - Photocuring coating composition, overprint, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocuring coating composition having excellent non-tackiness and transparency, to provide an overprint having excellent non-tackiness and transparency and to provide its manufacturing method. <P>SOLUTION: The photocuring coating composition contains a compound (A) represented by formula (I), a photopolymerization initiator (B) and a compound (C) having an ethylenically unsaturated bond. The overprint using the photocuring coating composition and its manufacturing method are also provided. In formula (I), X denotes O, S or NR, R denotes a hydrogen atom, an alkyl group or an acyl group, R<SP>1</SP>to R<SP>8</SP>each independently denotes a hydrogen atom or a monovalent substituent, R<SP>9</SP>to R<SP>10</SP>each independently denotes a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group and each adjacent two of R<SP>1</SP>to R<SP>10</SP>may be bonded to each other to form a ring. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photocurable coating composition, an overprint, and a method for producing the same. More specifically, the present invention relates to a photocurable coating composition that can be cured by irradiation with active radiation such as an electron beam and ultraviolet rays. In particular, light for coating an image created by arranging ink and / or toner on a printing substrate (image receiving substrate) by a method such as planographic printing, relief printing, intaglio printing, screen printing, ink jetting, and electrophotography. The present invention relates to a curable coating composition. Furthermore, it relates to photocurable overprint compositions that can be used particularly suitably for coating toner-based prints printed by electrophotography.

In recent years, a large number of actinic radiation curable compositions that can be used for UV-curable printing inks, paints, and coatings have been developed and are now being popularized. However, it is difficult to obtain a photocurable composition that satisfies all of the curability, surface smoothness, strength, storage stability, and the like.
In particular, toner-based images such as electrophotography are more difficult to obtain the desired performance when a feather oil layer is present on the image surface.
In a conventional method for generating a toner-based image, such as electrophotography, an electrostatic charge is formed on the surface of the latent image carrier by uniformly charging the surface of the latent image carrier, for example, a photoreceptor. Let Then, the uniformly charged area is selectively released by the activation irradiation pattern corresponding to the image of the original. The latent image charge pattern remaining on the surface corresponds to the areas not exposed to irradiation. The photoreceptor is then passed through one or more development housings containing toner, so that the toner adheres in a charge pattern due to electrostatic attraction, thereby visualizing the latent image charge pattern. The developed image is then fixed to the imaging surface or transferred to a printing substrate, such as paper, and fixed to it by a suitable fixing technique to obtain an electrophotographic print, i.e. a toner-based print. .

As a known method for protecting a printed matter, it has been proposed to apply an overprint coating to the printed matter. For example, Patent Documents 1 and 2 propose a method of covering the surface by performing fixing after transferring a transparent toner onto a toner-based image, such as electrophotography.
Patent Document 3 proposes a method of performing overprint coating by applying a liquid film coating that can be cured by ultraviolet rays or the like, and polymerizing (crosslinking) the coating components with light.

  On the other hand, conventionally, a method for increasing the sensitivity to radiation in a radiation curable polymerizable compound by using a sensitizer together with a photopolymerization initiator has been proposed, and the use of various polymerization initiation systems has been disclosed. For example, it has been proposed to use a thioxanthone compound as a sensitizer (Patent Document 4 and Patent Document 5).

JP-A-11-70647 JP 2003-241414 A JP-A-61-210365 JP-A-6-308727 JP-A-56-143202

  The problems to be solved by the present invention include a photocurable coating composition excellent in non-tackiness and transparency, and an overshoot excellent in non-tackiness and transparency using the photocurable coating composition. It is to provide a print and a manufacturing method thereof.

The above object was achieved by <1>, <6> or <7> described below. It is described below together with <2> to <5> which are preferred embodiments.
<1> A photocurable coating composition comprising (A) a compound represented by the following formula (I), (B) a photopolymerization initiator, and (C) a compound having an ethylenically unsaturated bond. object,

（式（I）中、ＸはＯ、Ｓ、又は、ＮＲを表し、Ｒは水素原子、アルキル基、又は、アシル基を表し、Ｒ¹〜Ｒ⁸はそれぞれ独立に水素原子、又は、一価の置換基を表し、Ｒ⁹及びＲ¹⁰はそれぞれ独立に水素原子、ハロゲン原子、アルキル基、又は、アルコキシ基を表し、また、Ｒ¹〜Ｒ¹⁰はそれぞれ隣接する２つが互いに連結して環を形成していてもよい。）

(In the formula (I), X represents O, S or NR, R represents a hydrogen atom, an alkyl group or an acyl group, and R ^{1 to} R ⁸ each independently represents a hydrogen atom or a monovalent group. R ⁹ and R ¹⁰ each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and R ^{1 to} R ¹⁰ each represent a ring formed by connecting two adjacent groups to each other. (It may be formed.)

<2> The photocurable coating composition according to <1>, wherein the photopolymerization initiator is an α-aminoketone compound and / or an acylphosphine oxide compound,
<3> The photocurable coating composition according to <1> or <2>, which has substantially no absorption in a visible region,
<4> The photocurable coating composition according to any one of the above <1> to <3>, which is for overprinting,
<5> The photocurable coating composition according to any one of the above <1> to <4>, which is for overprinting of an electrophotographic printed material,
<6> An overprint having an overprint layer obtained by photocuring the photocurable coating composition according to any one of <1> to <5> above on an electrophotographic printed material,
<7> A step of obtaining an electrophotographic printed material by electrophotographic printing on a printing substrate, and coating the photocurable coating composition according to any one of <1> to <5> above on the electrophotographic printed material. And a method of photocuring the photocurable coating composition.

  According to the present invention, a photocurable coating composition excellent in non-tackiness and transparency, and an overprint excellent in non-tackiness and transparency using the photocurable coating composition and its production Could provide a way.

  Hereinafter, the present invention will be described in detail.

(Photocurable coating composition)
The photocurable coating composition of the present invention contains (A) a compound represented by the following formula (I), (B) a photopolymerization initiator, and (C) a compound having an ethylenically unsaturated bond. Features.
The overprint of the present invention preferably has an overprint layer obtained by photocuring the above photocurable coating composition on an electrophotographic printed material.
The overprint production method of the present invention includes a step of electrophotographic printing on a printing substrate to obtain an electrophotographic printed matter, a step of applying the above-described photocurable coating composition on the electrophotographic printed matter, and the light It is preferable to include a step of photocuring the curable coating composition.

（式（I）中、ＸはＯ、Ｓ、又は、ＮＲを表し、Ｒは水素原子、アルキル基、又は、アシル基を表し、Ｒ¹〜Ｒ⁸はそれぞれ独立に水素原子、又は、一価の置換基を表し、Ｒ⁹及びＲ¹⁰はそれぞれ独立に水素原子、ハロゲン原子、アルキル基、又は、アルコキシ基を表し、また、Ｒ¹〜Ｒ¹⁰はそれぞれ隣接する２つが互いに連結して環を形成していてもよい。）

(In the formula (I), X represents O, S or NR, R represents a hydrogen atom, an alkyl group or an acyl group, and R ^{1 to} R ⁸ each independently represents a hydrogen atom or a monovalent group. R ⁹ and R ¹⁰ each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and R ^{1 to} R ¹⁰ each represent a ring formed by connecting two adjacent groups to each other. (It may be formed.)

The photocurable coating composition of the present invention preferably has substantially no absorption in the visible range. “Substantially no absorption in the visible region” means that there is no absorption in the visible region of 400 to 700 nm, or there is absorption in the visible region only to the extent that there is no problem as a photocurable coating composition. It means not. Specifically, it means that the 5 μm optical path length transmittance of the coating composition is 70% or more, preferably 80% or more in the wavelength range of 400 to 700 nm.
The photocurable coating composition of the present invention can be suitably used for overprinting, and can be particularly suitably used for overprinting of electrophotographic prints.
The photocurable coating composition of the present invention is excellent in non-tackiness and transparency, gloss and gloss even when an overprint layer is formed on an electrophotographic print having an image portion having a thickness equivalent to the toner. An overprint can be given and an impression similar to a conventional silver salt photographic print can be given visually.
In addition, the photocurable coating composition of the present invention is excellent in non-tackiness and transparency, gloss, gloss, and flexibility with little warping, even for a toner image having a feather oil layer on the image surface. A rich printed image can be obtained, and an overprint visually close to a silver salt photographic print can be obtained.

(A) Compound represented by formula (I) (sensitizer)
The photocurable coating composition of the present invention is characterized by containing a compound represented by the following formula (I) in order to promote the decomposition of the photopolymerization initiator by irradiation with actinic radiation.
The compound represented by the formula (I) acts as a sensitizer in the photocurable coating composition of the present invention.

（式（I）中、ＸはＯ、Ｓ、又は、ＮＲを表し、Ｒは水素原子、アルキル基、又は、アシル基を表し、Ｒ¹〜Ｒ⁸はそれぞれ独立に水素原子、又は、一価の置換基を表し、Ｒ⁹及びＲ¹⁰はそれぞれ独立に水素原子、ハロゲン原子、アルキル基、又は、アルコキシ基を表し、また、Ｒ¹〜Ｒ¹⁰はそれぞれ隣接する２つが互いに連結して環を形成していてもよい。）

(In the formula (I), X represents O, S or NR, R represents a hydrogen atom, an alkyl group or an acyl group, and R ^{1 to} R ⁸ each independently represents a hydrogen atom or a monovalent group. R ⁹ and R ¹⁰ each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and R ^{1 to} R ¹⁰ each represent a ring formed by connecting two adjacent groups to each other. (It may be formed.)

In the formula (I), X represents O, S, or NR, and R represents a hydrogen atom, an alkyl group, or an acyl group. n represents an integer of 0 to 4.
X is preferably O or S, and more preferably S.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represent a hydrogen atom or a monovalent substituent.
When R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent, examples of the monovalent substituent include a halogen atom, aliphatic group, aromatic Group, heterocyclic group, cyano group, hydroxy group, nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureido group, sulfamoylamino group, alkylthio group, arylthio Group, alkoxycarbonylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, substituted sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryloxy Carbonylamino group, imide group, heterocyclic thio group, substituted sulfinyl group, substituted phosphoryl group, acyl Group, a carboxy group, or a sulfo group. Further, a group in which two or more of these are combined may be used. Among these, an alkyl group, a halogen atom, an alkoxy group, an alkylthio group, and a carboxy group are preferable, and an alkyl group and a halogen atom are more preferable.

R ⁹ and R ¹⁰ each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group. Among these, a hydrogen atom, an alkyl group, and a halogen atom are preferable, and R ⁹ and R ¹⁰ are both most preferably a hydrogen atom.

Examples of the alkyl group when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ in formula (I) represent a monovalent substituent include a methyl group, an ethyl group, and propyl Group having 1 to 4 carbon atoms such as isopropyl group, n-butyl group, sec-butyl group and t-butyl group is preferable, and methyl group, ethyl group, propyl group and isopropyl group are more preferable, A methyl group and an ethyl group are particularly preferable.
Similarly, the alkoxy group has 1 to 4 carbon atoms such as methoxy group, ethoxy group, hydroxyethoxy group, isopropoxy group, propoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and t-butoxy group. Preferably, a methoxy group, an ethoxy group, an isopropoxy group, and a propoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable.
Similarly, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, a chlorine atom, a bromine atom and an iodine atom are more preferred, and a chlorine atom and a bromine atom are particularly preferred.

Specific examples and preferred ranges of the halogen atom, alkyl group and alkoxy group represented by R ⁹ and R ¹⁰ in formula (I) are the halogen atoms and alkyl groups described above as substituents represented by R ^{1 to} R ^8. And the same as the alkoxy group.

  The compound represented by the formula (I) is preferably a compound represented by the following formula (I-A).

In the formula (IA), X represents O or S.
R ^1A , R ^2A , R ^3A , R ^4A , R ^5A , R ^6A , R ^7A and R ^8A are each independently a hydrogen atom, halogen atom, hydroxy group, cyano group, nitro group, amino group, alkylthio group, alkyl It represents an amino group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, a carboxy group or a sulfo group.
R ^9A and R ^10A each independently represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group.

  The compound represented by the formula (I) is preferably a compound represented by the following formula (I-B).

In the formula (IB), R ^1B , R ^2B , R ^3B , R ^4B , R ^5B , R ^6B , R ^7B and R ^8B are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a nitro group, An amino group, an alkylthio group, an alkylamino group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, a carboxyl group, or a sulfo group is represented.
R ^9B and R ^10B each independently represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group.

    Specific examples of the compound represented by formula (I) that can be suitably used in the present invention [Exemplary compounds (I-1) to (I-30)] are shown below, but the present invention is limited to these. is not. In the following specific examples, Me represents a methyl group, t-Bu represents a t-butyl group, and n-Bu represents an n-butyl group. In the present invention, in the chemical formula, the hydrocarbon chain may be described by a simplified structural formula in which symbols of carbon (C) and hydrogen (H) are omitted.

  Examples of the compound represented by the formula (I) include I-4, I-5, I-6, I-7, I-12, I-19, I-21, I-22, and I-23. It is preferable that the compound has an electron withdrawing group such as I-4, I-5, I-12, I-19, I-21, I-22, I-23, and the like. It is more preferable that the compound has a high group.

  Generally, a sensitizer absorbs specific actinic radiation and enters an electronically excited state. A sensitizer in an electronically excited state is brought into contact with a polymerization initiator to cause an action such as electron transfer, energy transfer, and heat generation, thereby causing a chemical change of the polymerization initiator, that is, decomposition, radical, acid or base. The generation of active species such as these causes the active species generated here to cause and accelerate the polymerization and curing reaction of the polymerizable compound described later.

  In the coating composition of the present invention, the compound represented by the formula (I) used as a sensitizer depends on the wavelength of actinic radiation that generates an initiating species in the photopolymerization initiator used in the coating composition of the present invention. A compound may be used, but considering that it is used for the curing reaction of the coating composition of the present invention, a compound having an absorption wavelength in the region of 300 nm to 450 nm is preferable.

  A method for synthesizing the compound represented by the formula (I) is not particularly limited, and a known method can be used. For example, JP-A-53-12896, “Synth. Commun.” Vol. 19, p 3349 (1989), and “Helv. Chim. Acta” Vol. 45, p1860 (1962) and the like.

The content of the compound represented by formula (I) in the coating composition of the present invention is preferably about 0.05 to 40% by weight, preferably 0.1 to 30% by weight, based on the solid content of the coating composition. More preferably, the content is more preferably 0.2 to 25% by weight.
In addition, since the compound represented by the formula (I) has almost no absorption in the visible light region, there is an advantage that there is no concern of affecting the hue of the coating composition even if an amount capable of producing the effect is added. I have it.
When the content in the coating composition of the present invention is described in relation to the photopolymerization initiator described later, the weight ratio of the photopolymerization initiator to the compound represented by formula (I) is preferably 200: 1 to 1: The amount is 200, more preferably 50: 1 to 1:50, still more preferably 20: 1 to 1: 5.

Further, from the viewpoint of transparency, the compound represented by the formula (I) has an absorbance at a wavelength of 400 nm of 0.3 nm when the compound represented by the formula (I) is formed into a film having a thickness of 1 g / cm ^2. The following compounds are preferable, 0.2 or less compounds are more preferable, and 0.1 or less compounds are further preferable.

[Other sensitizers]
In the present invention, in addition to the compound represented by the formula (I), a known sensitizer can be used in combination as long as the effects of the present invention are not impaired.
When other sensitizers are used, the amount of other sensitizers used is the weight ratio of the compound represented by formula (I) to the other sensitizers relative to the compound represented by formula (I). The amount is preferably 1: 5 to 100: 1, more preferably 1: 1 to 100: 1, and even more preferably 2: 1 to 100: 1.

Examples of known sensitizers that can be used in combination include benzophenone, thioxanthone, isopropylthioxanthone, anthraquinone, 3-acylcoumarin derivatives, terphenyl, styryl ketone, 3- (aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine and Examples include erythrosin.
Further examples of sensitizers that can be used in combination are as follows.

(1) Thioxanthone Thioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3- ( 2-methoxyethoxycarbonyl) thioxanthone, 4-butoxycarbonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3- Ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfylthioxanthone, 3,4-di -[2- (2-methoxyethoxy) ethoxycarbonyl] thioxanthone, 1-ethoxycarbonyl-3- (1-methyl-1-morpholinoethyl) thioxanthone, 2-methyl-6-dimethoxymethylthioxanthone, 2-methyl-6- (1,1-dimethoxybenzyl) thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, n-allylthioxanthone-3,4-dicarboximide, n-octylthioxanthone-3,4-dicarboxy Imido, N- (1,1,3,3-tetramethylbutyl) thioxanthone-3,4-dicarboximide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methyl Thioxanthone Thioxanthone-2-polyethylene glycol ester, 2-hydroxy-3- (3,4-dimethyl-9-oxo -9H- thioxanthone-2-yloxy) -N, N, N-trimethyl-1-propanaminium chloride;

(2) Benzophenone Benzophenone, 4-phenylbenzophenone, 4-methoxybenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-dimethylbenzophenone, 4,4′-dichlorobenzophenone, 4,4′-dimethylaminobenzophenone, 4 , 4'-diethylaminobenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4- (4-methylthiophenyl) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, methyl-2-benzoylbenzoate 4- (2-hydroxyethylthio) benzophenone, 4- (4-tolylthio) benzophenone, 4-benzoyl-N, N, N-trimethylbenzenemethanaminium chloride, 2-hydroxy-3- (4-benzoylphenoxy) ) -N, N, N-trimethyl-1-propanaminium chloride monohydrate, 4- (13-acryloyl-1,4,7,10,13-pentaoxatridecyl) benzophenone, 4-benzoyl-N , N-dimethyl-N- [2- (1-oxo-2-propenyl) oxy] ethylbenzenemethanaminium chloride;

(3) 3-acylcoumarin 3-benzoylcoumarin, 3-benzoyl-7-methoxycoumarin, 3-benzoyl-5,7-di (propoxy) coumarin, 3-benzoyl-6,8-dichlorocoumarin, 3-benzoyl- 6-chlorocoumarin, 3,3′-carbonylbis [5,7-di (propoxy) coumarin], 3,3′-carbonylbis (7-methoxycoumarin), 3,3′-carbonylbis (7-diethylaminocoumarin) ), 3-isobutyroylcoumarin, 3-benzoyl-5,7-dimethoxycoumarin, 3-benzoyl-5,7-diethoxycoumarin, 3-benzoyl-5,7-dibutoxycoumarin, 3-benzoyl-5 7-di (methoxyethoxy) coumarin, 3-benzoyl-5,7-di (allyloxy) coumarin, 3-benzoyl-7- Dimethylaminocoumarin, 3-benzoyl-7-diethylaminocoumarin, 3-isobutyroyl-7-dimethylaminocoumarin, 5,7-dimethoxy-3- (1-naphthoyl) coumarin, 5,7-dimethoxy-3- (1-naphthoyl) ) Coumarin, 3-benzoylbenzo [f] coumarin, 7-diethylamino-3-thienoylcoumarin, 3- (4-cyanobenzoyl) -5,7-dimethoxycoumarin;

(4) 3- (Aroylmethylene) thiazoline 3-methyl-2-benzoylmethylene-β-naphthothiazoline, 3-methyl-2-benzoylmethylenebenzothiazoline, 3-ethyl-2-propionylmethylene-β-naphthothiazoline;

(5) Anthracene 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dimethoxy-2-ethylanthracene;

(6) Other carbonyl compounds Acetophenone, 3-methoxyacetophenone, 4-phenylacetophenone, benzyl, 2-acetylnaphthalene, 2-naphthaldehyde, 9,10-naphtholaquinone, 9-fluorenone, dibenzosuberone, xanthone, 2,5 -Bis (4-diethylaminobenzylidene) cyclopentanone, α- (para-dimethylaminobenzylidene) ketone, such as 2- (4-dimethylaminobenzylidene) indan-1-one or 3- (4-dimethylaminophenyl)- 1-Indan-5-ylpropenone, 3-phenylthiophthalimide, N-methyl-3,5-di (ethylthio) phthalimide.

(B) Photopolymerization initiator The coating composition of the present invention contains a photopolymerization initiator.
A known polymerization initiator can be used as the photopolymerization initiator. In the present invention, it is preferable to use a radical photopolymerization initiator.
The photopolymerization initiator used in the coating composition of the present invention is a compound that generates a polymerization initiating species by absorbing actinic radiation. Examples of the active radiation used for initiating the polymerization include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays.
Although the wavelength to be used is not specifically limited, Preferably it is a 200-500 nm wavelength range, More preferably, it is a 200-450 nm wavelength range.

<Radical photopolymerization initiator>
Preferred radical photopolymerization initiators that can be used in the present invention include (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e ) Thio compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon Examples include compounds having a halogen bond, and (m) alkylamine compounds.
Examples of the radical photopolymerization initiator described above include the radical photopolymerization initiators described in paragraph numbers [0135] to [0208] of the specification of JP-A-2006-085049.
A preferable photopolymerization initiator from the viewpoint of transparency is preferably a compound having an absorbance at a wavelength of 400 nm of 0.3 or less when the photopolymerization initiator is formed to a thickness of 3 g / cm ² , more preferably, A compound of 0.2 or less is more preferred, and a compound of 0.1 or less is more preferred.
A radical photoinitiator may be used individually by 1 type, and may use 2 or more types together.
Among the above, from the viewpoint of the relationship with the compound represented by the formula (I) used in the present invention and transparency, the photopolymerization initiator includes an α-aminoketone compound and / or an acylphosphine oxide compound. Is preferable, and it is particularly preferable to use an α-aminoketone compound and an acylphosphine oxide compound in combination.

  The α-aminoketone compound is preferably a compound represented by the following formula (1).

In the formula (1), Ar is a phenyl group substituted with —SR ¹³ or —N (R ⁷ ) (R ⁸ ), wherein R ¹³ represents a hydrogen atom or an alkyl group.
R ¹ and R ² are each independently an alkyl group having 1 to 8 carbon atoms. R ¹ and R ² may be bonded to each other to form an alkylene group having 2 to 9 carbon atoms.
R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 2 to 4 carbon atoms substituted with 1 to 4 carbon atoms, or 3 to 5 carbon atoms. Represents an alkenyl group. Here, R ³ and R ⁴ may be bonded to each other to form an alkylene group having 3 to 7 carbon atoms, and the alkylene group is —O— or —N (R ¹² ) — in the alkylene chain. Wherein R ¹² represents an alkyl group having 1 to 4 carbon atoms.
R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms substituted with 2 to 4 carbon atoms, or an alkenyl having 3 to 5 carbon atoms. Represents a group. Here, R ⁷ and R ⁸ may be bonded to each other to form an alkylene group having 3 to 7 carbon atoms, and the alkylene group is —O— or —N (R ¹² ) — in the alkylene chain. May be included. Here, R ¹² has the same meaning as described above.

  Examples of the compounds included in the α-amino ketones include 2-methyl-1-phenyl-2-morpholinopropan-1-one, 2-methyl-1- [4- (hexyl) phenyl] -2- And morpholinopropan-1-one, 2-ethyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, and the like. In addition, Irgacure series manufactured by Ciba Geigy, for example, Irgacure 907, Irgacure 369, Irgacure 379, and the like are also available as commercial products, and these are compounds included in α-amino ketones and are suitable for the present invention. Can be used for

  The acylphosphine oxide compound is preferably a compound represented by the following formula (2) or formula (3).

In the formula (2), R ⁵ and R ⁶ each independently represents an aliphatic group, an aromatic group, an aliphatic oxy group, an aromatic oxy group, or a heterocyclic group, and R ⁷ represents an aliphatic group or an aromatic group. Represents a group or heterocyclic group.
Examples of the aliphatic group in R ⁵ , R ⁶ or R ⁷ include an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group, and a substituted aralkyl group. Among these, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group, or a substituted aralkyl group is preferable, and an alkyl group and a substituted alkyl group are particularly preferable. The aliphatic group may be a cyclic aliphatic group or a chain aliphatic group. The chain aliphatic group may have a branch.

  Examples of the alkyl group include linear, branched, and cyclic alkyl groups, and the number of carbon atoms of the alkyl group is preferably 1 to 30, and more preferably 1 to 20. The preferred range of the number of carbon atoms in the alkyl part of the substituted alkyl group is the same as in the case of the alkyl group. Further, the alkyl group may be either a substituted alkyl group or an unsubstituted alkyl group. Examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, octadecyl, cyclohexyl, cyclopentyl, neopentyl, An isopropyl group, an isobutyl group, etc. are mentioned.

Examples of the substituent of the substituted alkyl group include a carboxyl group, a sulfo group, a cyano group, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom), a hydroxy group, and an alkoxycarbonyl group having 30 or less carbon atoms (for example, methoxycarbonyl). Group, ethoxycarbonyl group, benzyloxycarbonyl group), alkylsulfonylaminocarbonyl group having 30 or less carbon atoms, arylsulfonylaminocarbonyl group, alkylsulfonyl group, arylsulfonyl group, acylaminosulfonyl group having 30 or less carbon atoms, carbon number 30 The following alkoxy groups (for example, methoxy group, ethoxy group, benzyloxy group, phenoxyethoxy group, phenethyloxy group, etc.), alkylthio groups having 30 or less carbon atoms (for example, methylthio group, ethylthio group, methylthioethylthioethyl group, etc.) An aryloxy group having 30 or less carbon atoms (eg, phenoxy group, p-tolyloxy group, 1-naphthoxy group, 2-naphthoxy group, etc.), nitro group, alkyl group having 30 or less carbon atoms, alkoxycarbonyloxy group, aryloxy A carbonyloxy group, an acyloxy group having 30 or less carbon atoms (for example, acetyloxy group, propionyloxy group, etc.), an acyl group having 30 or less carbon atoms (for example, acetyl group, propionyl group, benzoyl group, etc.), carbamoyl group (for example, Carbamoyl group, N, N-dimethylcarbamoyl group, morpholinocarbonyl group, piperidinocarbonyl group, etc.), sulfamoyl group (for example, sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfonyl group, piperidinosulfonyl group) Etc.), an aryl group having 30 or less carbon atoms For example, phenyl group, 4-chlorophenyl group, 4-methylphenyl group, α-naphthyl group, etc.), substituted amino group (for example, amino group, alkylamino group, dialkylamino group, arylamino group, diarylamino group, acylamino group) Etc.), substituted ureido groups, substituted phosphono groups, heterocyclic groups and the like. Here, the carboxyl group, the sulfo group, the hydroxy group, and the phosphono group may be in a salt state. At that time, examples of the cation forming the salt include M ⁺ described later.

  Examples of the alkenyl group include linear, branched, and cyclic alkenyl groups. The number of carbon atoms of the alkenyl group is preferably 2 to 30, and more preferably 2 to 20. The alkenyl group may be a substituted alkenyl group having a substituent or an unsubstituted alkenyl group, and the preferred range of the number of carbon atoms in the alkenyl part of the substituted alkenyl group is the same as that of the alkenyl group. . Examples of the substituent of the substituted alkenyl group include the same substituents as those of the substituted alkyl group.

  Examples of the alkynyl group include linear, branched, and cyclic alkynyl groups, and the number of carbon atoms of the alkynyl group is preferably 2 to 30, and more preferably 2 to 20. The alkynyl group may be a substituted alkynyl group having a substituent or an unsubstituted alkynyl group, and the preferred range of the number of carbon atoms in the alkynyl part of the substituted alkynyl group is the same as in the case of the alkynyl group. . Examples of the substituent for the substituted alkynyl group include the same substituents as those for the substituted alkyl group.

  Examples of the aralkyl group include linear, branched, and cyclic aralkyl groups. The number of carbon atoms in the aralkyl group is preferably 7 to 35, and more preferably 7 to 25. The aralkyl group may be a substituted aralkyl group having a substituent or an unsubstituted aralkyl group, and the preferred range of the number of carbon atoms in the aralkyl part of the substituted aralkyl group is the same as in the case of the aralkyl group. . Examples of the substituent for the substituted aralkyl group include the same substituents as those for the substituted alkyl group.

Examples of the aromatic group represented by R ⁵ , R ⁶ or R ⁷ include an aryl group and a substituted aryl group. As a carbon atom number of an aryl group, 6-30 are preferable and 6-20 are more preferable. The preferable range of the number of carbon atoms in the aryl part of the substituted aryl group is the same as that of the aryl group. Examples of the aryl group include a phenyl group, an α-naphthyl group, a β-naphthyl group, and the like. Examples of the substituent for the substituted aryl group include the same substituents as those for the substituted alkyl group.

Examples of the aliphatic oxy group represented by R ⁵ or R ⁶ include substituted or unsubstituted alkoxy groups, alkenyloxy groups, alkynyloxy groups, aralkyloxy groups, and the like. A substituted or unsubstituted alkoxy group is preferable, and examples thereof include a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, and a phenoxyethoxy group. However, it is not limited to these.

Examples of the aromatic oxy group represented by R ⁵ or R ⁶ include a substituted or unsubstituted aryloxy group, preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, such as a phenoxy group. Methylphenyloxy group, chlorophenyloxy group, methoxyphenyloxy group, octyloxyphenyloxy group and the like. However, it is not limited to these.

The heterocyclic group represented by R ⁵ , R ⁶ or R ⁷ is preferably a heterocyclic group containing an N, O or S atom, for example, a pyridyl group, a furyl group, a thienyl group, an imidazolyl group, a pyrrolyl group or the like. Is mentioned.

In addition, the compound represented by the formula (2) is bonded to another compound represented by the formula (2) in R ⁵ , R ⁶ or R ⁷ to form a multimer having two or more acylphosphine structures. May be.

R ⁸ and R ¹⁰ in the formula (3) each independently represent an alkyl group, an aryl group, or a heterocyclic group, and R ⁹ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or a heterocyclic group. To express. The alkyl group, aryl group, heterocyclic group, alkoxy group and aryloxy group represented by R ⁸ , R ⁹ or R ¹⁰ may have a substituent. The same substituents as in the case of (2) can be mentioned.
The alkyl group, aryl group, heterocyclic group, alkoxy group and aryloxy group in the formula (3) have the same meaning as in the formula (2).
In addition, the compound represented by the formula (3) is bonded to another compound represented by the formula (3) in R ⁸ , R ⁹ or R ¹⁰ to form a multimer having two or more acylphosphine structures. May be.

  Examples of the acylphosphine oxide compound represented by the formula (2) or formula (3) include Japanese Patent Publication No. 63-40799, Japanese Patent Publication No. 5-29234, and Japanese Patent Application Laid-Open No. 10-95788. And compounds described in JP-A-10-29997.

  Specific examples of the acylphosphine oxide compound include the following compounds (Exemplary compounds (P-1) to (P-26)), but the present invention is not limited to these compounds. Absent.

  Among the exemplified compounds, for example, (P-2): 2,4,6-trimethylbenzoyldiphenylphosphine oxide is available under the trade name DAROCUR TPO (manufactured by Ciba Specialty Chemicals), and (P-19 ): Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide is available under the trade name IRGACURE 819 (Ciba Specialty Chemicals).

In the photocurable coating composition of the present invention, a photopolymerization initiator other than an α-aminoketone compound and an acylphosphine oxide compound may be used as a photopolymerization initiator, or may be used in combination.
Examples of known polymerization initiators that can be used in combination include camphorquinone, benzophenone, benzophenone derivatives, acetophenone, acetophenone derivatives, such as α-hydroxycycloalkyl phenyl ketones or 2-hydroxy-2-methyl-1-phenyl-propanone. Dialkoxyacetophenones, α-hydroxy- or 4-aroyl-1,3-dioxolanes, benzoin alkyl ethers and benzyl ketals, for example, benzyl dimethyl ketal, phenyl glyoxalate and its derivatives, dimeric phenyl glyoxalate Peresters such as benzophenone tetracarboxylic acid peresters (eg as described in EP 1,126,541), halomethyltriazines such as 2- [2- (4-methoxyphenyl) vinyl] -4,6-bistrichloromethyl-1,3,5-triazine, 2- (4-methoxyphenyl) -4,6-bistrichloromethyl-1,3,5-triazine, 2- (3,4-dimethoxyphenyl) -4,6-bis-trichloromethyl-1,3,5-triazine, 2-methyl-4,6-bistrichloromethyl-1,3,5-triazine, hexaaryl Bisimidazole / co-initiator systems such as ortho-chlorohexaphenyl-bisimidazole in combination with 2-mercaptobenzothiazole; ferrocenium compounds or titanocenes such as dicyclopentadienyl bis (2,6-difluoro -3-pyrrolo-phenyl) titanium; for example, British Patent 2,339,571 It is also possible to use a mixture of O- acyloxime ester compounds as described in the book. A boric acid compound can also be used as a co-initiator.

The content of the photopolymerization initiator in the photocurable coating composition of the present invention is preferably in the range of 0.1 to 30% by weight and in the range of 0.2 to 20% by weight in terms of solid content. More preferably.
The photopolymerization initiator is a weight ratio of polymerization initiator: sensitizing dye to the compound represented by the above formula (I) in the range of 200: 1 to 1: 200, preferably 50: 1 to 1. : 50, more preferably within a range of 20: 1 to 1: 5.

In the present invention, as the cationic polymerization initiator (photoacid generator) used in combination with the above cationic polymerizable compound, for example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (for example, organic electronics). (Refer to Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), pages 187 to 192).
Examples of the cationic polymerization initiator suitable for the present invention are listed below.
That is, first, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of an aromatic onium compound such as diazonium, ammonium, iodonium, sulfonium or phosphonium. Can be mentioned. Secondly, sulfonated products that generate sulfonic acid can be mentioned. Thirdly, a halide that generates hydrogen halide by light can also be used. Fourthly, iron arene complexes can be mentioned.
A cationic polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

(C) Compound having ethylenically unsaturated bond The coating composition of the present invention contains (C) a compound having an ethylenically unsaturated bond.
The compound having an ethylenically unsaturated bond that can be used in the present invention is not particularly limited as long as it is a compound capable of radical polymerization or cationic polymerization.

The radical polymerizable compound in the present invention may be any compound as long as it has at least one ethylenically unsaturated bond, and includes monomers, oligomers, polymers, and the like.
Only one type of radically polymerizable compound may be used, or two or more types thereof may be used in combination at an arbitrary ratio in order to improve target properties. From the viewpoint of controlling performance such as reactivity and physical properties, it is preferable to use two or more kinds of radically polymerizable compounds in combination.

  Examples of radically polymerizable compounds include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and other unsaturated carboxylic acids and salts thereof, anhydrides having ethylenically unsaturated bonds, acrylonitrile, styrene Furthermore, radically polymerizable compounds such as various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides and unsaturated urethanes can be mentioned.

  Specifically, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4- (Acryloxypolyethoxyphenyl) propane, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene Glycol diacrylate, pentaerythritol tria Relate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, N-methylol acrylamide, diacetone acrylamide, epoxy acrylate and other acrylic acid derivatives, methyl methacrylate, n -Butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate Methacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, methacryl derivatives such as 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, N-vinylpyrrolidone, N-vinylcaprolactam, etc. Derivatives of allyl compounds such as N-vinyl compounds, allyl glycidyl ether, diallyl phthalate, triallyl trimellitate, and the like. More specifically, Yamashita Shinzo, “Cross-linking agent handbook” (1981, Taisei Kato Kiyomi, "UV / EB Curing Handbook (Raw Materials)" (1985, Polymer Publishing Society); Radtech Research Group, "Application and Market of UV / EB Curing Technology", page 79, ( 1989, CMC); Eiichiro Takiyama, “Poly Commercially available products described in "Ester Resin Handbook", (1988, Nikkan Kogyo Shimbun) or radically polymerizable or crosslinkable monomers, oligomers and polymers known in the industry can be used.

  Examples of the radical polymerizable compound include those disclosed in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011, and the like. Photocurable polymeric compound materials used for the described photopolymerizable compositions are known and can also be applied to the coating compositions of the present invention.

Furthermore, it is also preferable to use a vinyl ether compound as the radical polymerizable compound. Suitable vinyl ether compounds include, for example, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, and cyclohexanedimethanol. Di- or trivinyl ether compounds such as divinyl ether and trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl Monovinyl ether compounds such as ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether, ethylene glycol monovinyl ether, triethylene glycol monovinyl ether, hydroxyethyl monovinyl ether, hydroxynonyl monovinyl ether, etc. Is mentioned.
Among these vinyl ether compounds, a divinyl ether compound or a trivinyl ether compound is preferable from the viewpoint of curability, adhesion, and surface hardness, and a divinyl ether compound is particularly preferable. A vinyl ether compound may be used individually by 1 type, and may be used in combination of 2 or more type as appropriate.

  Examples of other polymerizable compounds that can be used in the present invention include (meth) acrylic monomers or prepolymers, epoxy monomers or prepolymers, or (meth) acrylic acid esters such as urethane monomers or prepolymers (hereinafter referred to as “polymeric esters”). As appropriate, it is also referred to as “acrylate compound”). More preferably, they are the following compounds.

  That is, 2-ethylhexyl diglycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxybutyl acrylate, hydroxypivalate neopentyl glycol diacrylate, 2-acryloyloxyethyl phthalate, methoxy-polyethylene glycol acrylate, tetra Methylol methane triacrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, dimethylol tricyclodecane diacrylate, ethoxylated phenyl acrylate, 2-acryloyloxyethyl succinic acid, nonylphenol ethylene oxide (EO) adduct acrylate , Modified glycerin triacrylate, bisphenol A diglycidyl ether acrylic acid adduct, modified bisphenol A diacrylic , Phenoxy-polyethylene glycol acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, propylene oxide (PO) adduct diacrylate of bisphenol A, EO adduct diacrylate of bisphenol A, dipentaerythritol hexaacrylate, pentaerythritol Triacrylate tolylene diisocyanate urethane prepolymer, lactone-modified flexible acrylate, butoxyethyl acrylate, propylene glycol diglycidyl ether acrylic acid adduct, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, 2-hydroxyethyl acrylate, Methoxydipropylene glycol acrylate, ditrimethylolpropane tetraacrylate Pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, stearyl acrylate, isoamyl acrylate, isomyristyl acrylate, isostearyl acrylate, lactone-modified acrylate.

These acrylate compounds can relatively reduce the viscosity, and the polymerization sensitivity and the adhesion to the recording medium are also good.
Further, the monomers listed here have high reactivity, low viscosity, and excellent adhesion to a recording medium.

In the present invention, in order to further improve non-tackiness (surface tackiness) and transparency, among the compounds represented by the formula (I) and the compound having an ethylenically unsaturated bond described above, a polyfunctional acrylate It is preferable to use the compound in combination.
As the polyfunctional acrylate, bisphenol A epoxy diacrylate and tripropylene glycol diacrylate can be particularly preferably exemplified.
Moreover, when using a polyfunctional ethylenically unsaturated compound, it is preferable that it is 5 to 80 weight% with respect to the total weight of a coating composition as content of a polyfunctional ethylenically unsaturated compound, 40-70 More preferably, it is% by weight. Within the above range, non-tackiness is excellent.
In the present invention, in addition to a combination of a radical polymerizable compound and a radical photopolymerization initiator according to various purposes, a cation polymerizable compound and a cationic polymerization initiator as shown below were used in combination with them. Alternatively, a radical / cation hybrid coating composition may be used.

The cationically polymerizable compound that can be used in the present invention is not particularly limited as long as it is a compound that initiates a polymerization reaction with an acid generated from a photoacid generator and cures, and various known compounds known as photocationically polymerizable monomers. Cationic polymerizable monomers can be used.
When the cationically polymerizable compound to be used does not have an ethylenically unsaturated bond, a compound having an ethylenically unsaturated bond and a cationically polymerizable compound having no ethylenically unsaturated bond are used in combination.
Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and 2001-2001. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in each publication such as No. 220526.

  In addition, as the cationic polymerizable compound, for example, a polymerizable compound applied to a cationic polymerization type photocurable resin is known, and recently, a photo cationic polymerization type sensitized in a visible light wavelength region of 400 nm or more. Examples of the polymerizable compound applied to the photo-curable resin are disclosed in JP-A-6-43633 and JP-A-8-324137. These can also be applied to the coating composition of the present invention.

The content of the compound (C) having an ethylenically unsaturated bond in the photocurable coating composition of the present invention is 10 to 97 weights with respect to the weight of the entire coating composition from the viewpoint of curability and surface smoothness. % Is preferable, a range of 30 to 95% by weight is more preferable, and a range of 50 to 90% by weight is particularly preferable.
Moreover, the compound which has (C) ethylenically unsaturated bond may be used by 1 type, and may use 2 or more types together.

<Co-sensitizer>
The coating composition of the present invention can also contain a co-sensitizer.
In the present invention, the co-sensitizer has functions such as further improving the sensitivity of the sensitizer to actinic radiation or suppressing polymerization inhibition of the polymerizable compound by oxygen.
Examples of such cosensitizers include amines such as M.I. R. Sander et al., “Journal of Polymer Society”, Vol. 10, 3173 (1972), Japanese Patent Publication No. 44-20189, Japanese Patent Publication No. 51-82102, Japanese Patent Publication No. 52-134692, Japanese Patent Publication No. 59-138205. And JP-A-60-84305, JP-A-62-18537, JP-A-64-33104, Research Disclosure 33825, and the like.
Specific examples include triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like.

Other examples of co-sensitizers include thiols and sulfides such as thiol compounds described in JP-A-53-702, JP-A-55-500806, and JP-A-5-142277, The disulfide compound of 56-75643 gazette etc. are mentioned.
Specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene and the like.

  Other examples include amino acid compounds (for example, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (for example, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (for example, trithiane), phosphorus compounds described in JP-A-6-250387 (for example, diethyl phosphite), Si described in JP-A-8-54735 -H, Ge-H compounds and the like.

<Surfactant>
The coating composition of the present invention may contain a surfactant.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. Further, an organic fluoro compound or a polysiloxane compound may be used as the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826. Among these, as the surfactant, polydimethylsiloxane can be preferably exemplified.
These surfactants may be used alone or in combination of two or more.

<Other ingredients>
If necessary, other components can be added to the coating composition of the present invention. Examples of other components include a polymerization inhibitor, a solvent, inorganic particles, and organic particles.
A polymerization inhibitor may be added from the viewpoint of enhancing the storage stability. The polymerization inhibitor is preferably added in an amount of 200 to 20,000 ppm based on the total amount of the coating composition of the present invention.
Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.
Inorganic particles such as aerosil and organic particles such as crosslinked polymethylmethacrylate (PMMA) are added to the coating composition of the present invention to form an overprint layer or overprint with a deliberately reduced surface gloss. be able to.

In view of the fact that the coating composition of the present invention is a radiation curable coating composition, it is preferable that the coating composition of the present invention does not contain a solvent so that it can react quickly and be cured after application. However, a predetermined solvent can be included as long as the curing rate of the coating composition is not affected.
In the present invention, an organic solvent can be used as the solvent, and it is preferable that water is not substantially added from the viewpoint of curing speed. An organic solvent can be added to improve adhesion to a printing substrate (image receiving substrate such as paper).
When using an organic solvent, the amount is preferably as small as possible, preferably 0.1 to 5% by weight, and preferably 0.1 to 3% by weight, based on the total weight of the coating composition of the present invention. Is more preferable.

In addition, known compounds can be added to the coating composition of the present invention as necessary.
For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes and the like are appropriately selected and added. be able to.

  Moreover, in order to improve the adhesiveness to printing base materials, such as polyolefin and a polyethylene terephthalate (PET), it is also preferable to contain the tackifier (tackifier) which does not inhibit superposition | polymerization. Specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, pages 5 to 6 (for example, (meth) acrylic acid and an alcohol having an alkyl group having 1 to 20 carbon atoms). Ester, (meth) acrylic acid and a C3-14 alicyclic alcohol ester, (meth) acrylic acid and a C6-14 aromatic alcohol ester copolymer), and polymerizability Examples thereof include a low molecular weight tackifying resin having an unsaturated bond.

<Properties of photocurable coating composition>
The preferred physical properties of the photocurable coating composition of the present invention will be described.
When used as a photocurable coating composition, the viscosity at 25 to 30 ° C. is preferably 5 to 100 mPa · s, more preferably 7 to 75 mPa · s in consideration of applicability.
It is preferable that the composition ratio of the photocurable coating composition of the present invention is appropriately adjusted so that the viscosity is in the above range.
By setting the viscosity at 25 to 30 ° C. to the above value, an overprint having an overprint layer excellent in non-tackiness (no surface stickiness) and excellent in surface smoothness can be obtained.
The surface tension of the photocurable coating composition of the present invention is preferably 16 to 40 mN / m, and more preferably 18 to 35 mN / m.

(Overprint and manufacturing method thereof)
The overprint of the present invention has an overprint layer obtained by photocuring the coating composition of the present invention on a printed material.
The overprint forms at least one overprint layer on the surface of a printed material obtained by a printing method such as electrophotographic printing, inkjet printing, screen printing, flexographic printing, planographic printing, intaglio printing, or relief printing. It is what.
The overprint layer in the overprint of the present invention may be formed on a part of the printed matter or on the entire surface of the printed matter. In the case of a double-sided printed matter, it is formed on the entire surface of both sides of the printing substrate. It is preferable. Needless to say, the overprint layer may be formed in a non-printed portion of the printed material.
The printed material used for the overprint of the present invention is preferably an electrophotographic printed material. By forming an overprint layer, which is a cured layer of the coating composition of the present invention, on an electrophotographic printed matter, it is excellent in non-tackiness, surface smoothness and gloss, and visually similar to a silver salt photographic print. Can be obtained.
The thickness of the overprint layer in the overprint of the present invention is preferably 1 to 10 μm, and more preferably 3 to 6 μm.

The overprint production method of the present invention includes a step of printing on a recording medium to obtain a printed material, a step of applying the photocurable coating composition of the present invention on the printed material, and photocuring the coating composition. It is preferable to include the process to do.
The overprint manufacturing method of the present invention includes a step of generating an electrostatic latent image on a latent image carrier, a step of developing the electrostatic latent image with toner, and printing the developed electrostatic image. The method further includes a step of transferring to a base material to obtain an electrophotographic printed material, a step of applying the photocurable coating composition of the present invention on the electrophotographic printed material, and a step of photocuring the coating composition. preferable.
The printing substrate is not particularly limited, and known materials can be used. However, image receiving paper is preferable, plain paper or coated paper is more preferable, and coated paper is further used. preferable. As the coated paper, a double-sided coated paper is preferable because a full color image can be printed on both sides beautifully. When the printing substrate is paper or double-side coated paper, the preferred basis weight is 20 to 200 g / m ² , and the more preferred basis weight is 40 to 160 g / m ² .

The method for developing an image in electrophotography is not particularly limited and can be arbitrarily selected from methods known to those skilled in the art. For example, a cascade method, a touchdown method, a powder cloud method, a magnetic brush method, and the like can be given.
Examples of the method for transferring the developed image to a recording medium include a method using a corotron or a bias roll.
A fixing step for fixing an image in the electrophotographic method can be performed by various appropriate methods. Examples thereof include flash fixing, heat fixing, pressure fixing, and vapor fixing.
The image forming method, apparatus, and system by electrophotography are not particularly limited, and known ones can be used. Specifically, as described in the following US patents.
US Pat. No. 4,585,884, US Pat. No. 4,584,253, US Pat. No. 4,563,408, US Pat. No. 4,265,990, US Pat. US Pat. No. 6,180,308, US Pat. No. 6,212,347, US Pat. No. 6,187,499, US Pat. No. 5,966,570, US Pat. No. 5,627,002, US Pat. No. 5,366,840; US Pat. No. 5,346,795, US Pat. No. 5,223,368, and US Pat. 826, 147 specification.

In order to apply the photocurable coating composition, a commonly used liquid film coating device can be used. Specifically, roll coaters, rod coaters, blades, wire bars, dipping, air knives, curtain coaters, slide coaters, doctor knives, screen coaters, gravure coaters such as offset gravure coaters, slot coaters, and extrusion coaters Etc. can be exemplified. These devices can be used in the same way as usual, but for example, direct and reverse roll coating, blanket coating, dampner coating, There are curtain coating, lithographic coating, screen coating, and gravure coating. In a preferred embodiment, the coating composition of the present invention is applied and cured using two or three roll coaters and a UV curing station.
Moreover, you may heat as needed at the time of application | coating and hardening of the coating composition of this invention.
Typical levels of coating weight of the coating composition of the present invention, a weight per unit area is preferably in the range of 1 to 10 g / m ^2, and more to be 3 to 6 g / m ² preferable.
The formation amount of the overprint layer in the overprint of the present invention, per unit area, is preferably in the range of 1 to 10 g / m ^2, more preferably 3 to 6 g / m ^2.

The energy source used to initiate the polymerization of the polymerizable compound contained in the coating composition of the present invention may be actinic, for example, radiation having a spectral ultraviolet or visible wavelength. ) (Active radiation). Polymerization by irradiation with actinic radiation is excellent in initiating polymerization and adjusting the polymerization rate.
Suitable actinic radiation irradiation sources include, for example, mercury lamps, xenon lamps, carbon arc lamps, tungsten filament lamps, lasers, sunlight, and the like.

  Under ultraviolet irradiation (UV light irradiation), irradiation with a medium pressure mercury lamp using a high-speed conveyor (preferably 20 to 70 m / min) is preferable, in which case UV light irradiation has a wavelength of 200 to 500 nm. And give for less than 1 second. More preferably, the speed of the high-speed conveyor is 15 to 35 m / min, and UV light having a wavelength of 200 to 450 nm is irradiated for 10 to 50 milliseconds (ms). The emission spectrum of the UV light source usually overlaps with the absorption spectrum of the UV polymerization initiator. Curing equipment used in some cases includes a reflector that collects and diffuses UV light, and a cooling system for removing heat generated by the UV light source. It is not limited.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the embodiments in these examples.

Example 1
The following components were stirred with a stirrer to obtain a photocurable coating composition.
Ebecryl 605 (Bisphenol A epoxy diacrylate, CYTEC SURFACE SPECIALTIES) 40% by weight
Tripropylene glycol diacrylate (Aldrich) 20% by weight
・ 20% by weight of dodecyl acrylate
・ IRGACURE 907 (Ciba Specialty Chemicals) 5% by weight
・ DAROCUR TPO (Ciba Specialty Chemicals) 5% by weight
Compound represented by formula (I) (the compound (I-1)) 8% by weight
Polydimethylsiloxane (Aldrich) 2% by weight

<Non-tackiness (surface stickiness suppression) evaluation>
It was obtained by applying a bar coating on one side of the electrophotographic printed matter outputted on a double-side coated paper with a digital printer (DC8000) manufactured by Fuji Xerox Co., Ltd. so that the coating composition had a film thickness of 5 g / m ² . The coated film was exposed to 120 mJ / cm ² at an illuminance of 1.0 W / cm ² using a Hamamatsu Photonics UV lamp (LC8) to prepare an overprint sample. The non-tackiness after exposure was evaluated by touch. The evaluation criteria are shown below.
◎: No stickiness ○: Almost no stickiness △: Some stickiness ×: There is stickiness

<Transparency (hue)>
On polyethylene terephthalate (PET), coating is performed with a bar coat so as to have a film thickness of 5 g / m ² , and the obtained coating film is used by using a UV lamp (LC8) manufactured by Hamamatsu Photonics. 500 mJ / cm ² exposure was performed at an illuminance of 0 W / cm ² to prepare an overprint sample. Visual evaluation of the obtained PET sheet, a sensory evaluation of hue (transparency), using a color difference meter CR-100 manufactured by Konica Minolta, combined perceptual chromaticity index a and b with the measurement results, Evaluation was made according to the following criteria. The results are shown in Table 1 below.
○: Excellent transparency (−2.0 ≦ a ≦ 0 and −6 ≦ b ≦ −2).
Δ: It was a level that yellow could be discriminated only by placing PET on white paper (the range was −4.0 ≦ a <−2.0 and −4 <b ≦ 0).
X: It was transparent with strong yellowishness (the values of a and b were outside the above ranges).

  As a result of evaluation by the above method, the non-tackiness of the photocurable coating composition of Example 1 was ○, and the transparency was ○.

(Comparative Example 1)
A photocurable coating composition was prepared in the same manner as in Example 1 except that IRGACURE 907 and DAROCUR TPO were each changed to 4% by weight (9% by weight as a whole) instead of the compound represented by the formula (I). The product was made. Further, performance evaluation was performed in the same manner as in Example 1.

(Examples 2 to 10, Comparative Examples 2 and 3)
A photocurable coating composition was prepared in the same manner as in Example 1 except that the compound represented by the formula (I) was changed to the compounds shown in Table 1. Further, performance evaluation was performed in the same manner as in Example 1.

(Example 11)
Twenty printed materials were produced by electrophotographic printing full color images of several frames on both sides of A4 size double-side coated paper (basis weight 100 g / m ² ). Each of the photocurable coating compositions prepared in 3 was applied in the same manner as in Example 1 so that the coating amount was 5 g / m ² , and then irradiated with ultraviolet rays to prepare an overprint. When these were bound into a photo album, a photo album with the same visibility as a silver salt photo print was obtained.

Example 12
Ten printed materials were produced by electrophotographic printing full color images and text including a menu photo on both sides of a substantially B4 size double-sided coated paper (basis weight 100 g / m ² ). Each of the photocurable coating compositions prepared in 1 and 3 was applied in the same manner as in Example 1 so that the coating amount was 5 g / m ^{2 on} one side, and then irradiated with ultraviolet rays to produce a double-sided overprint. did. When these were bound into a restaurant menu, a restaurant menu was obtained that had the same visibility as a silver halide photographic print.

Claims (7)

(A) a compound represented by the following formula (I),
(B) a photopolymerization initiator, and
(C) A photocurable coating composition comprising a compound having an ethylenically unsaturated bond.

(In the formula (I), X represents O, S or NR, R represents a hydrogen atom, an alkyl group or an acyl group, and R ^{1 to} R ⁸ each independently represents a hydrogen atom or a monovalent group. R ⁹ and R ¹⁰ each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and R ^{1 to} R ¹⁰ each represent a ring formed by connecting two adjacent groups to each other. (It may be formed.)   The photocurable coating composition according to claim 1, wherein the photopolymerization initiator is an α-aminoketone compound and / or an acylphosphine oxide compound.   The photocurable coating composition according to claim 1 or 2, which has substantially no absorption in the visible region.   The photocurable coating composition according to claim 1, which is used for overprinting.   The photocurable coating composition according to any one of claims 1 to 4, which is for overprinting of electrophotographic printed matter.   The overprint which has the overprint layer which photocured the photocurable coating composition as described in any one of Claims 1-5 on an electrophotographic printed material. A step of obtaining an electrophotographic print by electrophotographic printing on a printing substrate;
Applying the photocurable coating composition according to any one of claims 1 to 5 on the electrophotographic printed material; and
A step of photocuring the photocurable coating composition.