JP2009079091A - Photocurable coating composition, overprint, and manufacturing method for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable coating composition having excellent surface smoothness, an overprint having excellent non-tackiness properties and surface smoothness, and a manufacturing method of the overprint produced by applying and curing the photocurable coating composition. <P>SOLUTION: The photocurable coating composition contains an ethylenic unsaturated compound having a cyclic amide group and/or a cyclic imide group, and a photopolymerization initiator. The photocurable coating composition has substantially no absorption in a visible range preferably and can be suitably used for an overprint of an electrophotographic printed matter. <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. More particularly, 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.
In addition, Patent Document 4 discloses a polyfunctional alkoxylated acrylic monomer or polycrystal comprising a radiation curable oligomer selected from the group consisting of trifunctional unsaturated acrylic resins and one or more di-acrylates or tri-acrylates. An overprint composition comprising a radiation curable monomer selected from the group consisting of alkoxylated acrylic monomers, at least one photopolymerization initiator, and at least one surfactant is disclosed.

JP-A-11-70647 JP 2003-241414 A JP-A-61-210365 JP-A-2005-321882

  The problem to be solved by the present invention is a photocurable coating composition excellent in surface smoothness, and an overprint excellent in non-tackiness and surface smoothness by applying and curing the photocurable coating composition. And a method of manufacturing the same.

The above object was achieved by <1>, <11> or <12> described below. It is described below together with <2> to <10> which are preferred embodiments.
<1> a photocurable coating composition comprising an ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group, and a photopolymerization initiator,
<2> The photocurable coating composition according to <1>, wherein the ethylenically unsaturated compound having a cyclic amide group is a compound represented by the formula (1):

式（１）中、Ｒ¹〜Ｒ⁷はそれぞれ独立に水素原子又は有機基を表し、ｎは０〜６の整数を表す。Ｒ¹〜Ｒ⁷のいずれか１つは、エチレン性不飽和結合を有する。

Wherein ^(1), R 1 ~R ⁷ each independently represent a hydrogen atom or an organic group, n represents an integer of 0 to 6. Any one of R ^{1 to} R ⁷ has an ethylenically unsaturated bond.

<3> The photocurable coating composition according to the above <2>, wherein n is an integer of 2 to 4 in the formula (1),
<4> The photocurable coating composition according to any one of <1> to <3> above, wherein the ethylenically unsaturated compound having a cyclic imide group is a compound represented by the formula (2):

式（２）中、Ｒ¹〜Ｒ⁵は、それぞれ独立に水素原子又は有機基を表し、ｎは０〜６の整数を表す。Ｒ¹〜Ｒ⁵のいずれか１つはエチレン性不飽和結合を有する。

Wherein (2), R ¹ ~R ⁵ each independently represent a hydrogen atom or an organic group, n represents an integer of 0 to 6. Any one of R ^{1 to} R ⁵ has an ethylenically unsaturated bond.

<5> In said Formula (2), n is an integer of 2-4, The photocurable coating composition as described in said <4>,
<6> The photocurable composition according to any one of <1> to <5>, wherein the ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group is a monofunctional ethylenically unsaturated compound. Coating composition,
<7> The photocurable coating composition according to any one of <1> to <6> above, which contains a polyfunctional ethylenically unsaturated compound,
<8> The photocurable coating composition according to any one of <1> to <7>, which has substantially no absorption in a visible region,
<9> The photocurable coating composition according to any one of <1> to <8>, which is for overprinting,
<10> The photocurable coating composition according to any one of <1> to <9> above, which is for overprinting of an electrophotographic printed material,
<11> An overprint having an overprint layer obtained by photocuring the photocurable coating composition according to any one of <1> to <10> above on an electrophotographic printed material,
<12> A step of obtaining an electrophotographic printed material by electrophotographic printing on a printing substrate, and applying the photocurable coating composition according to any one of <1> to <10> 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 surface smoothness, an overprint excellent in non-tackiness and surface smoothness by applying and curing the photocurable coating composition, and a method for producing the same Could be provided.

The photocurable coating composition of the present invention contains an ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group, and a photopolymerization initiator.
The overprint of the present invention has an overprint layer obtained by photocuring the 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 Photocuring the curable coating composition.
Hereinafter, the present invention will be described in detail.

(Photocurable coating composition)
The photocurable coating composition of the present invention contains an ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group, and a photopolymerization initiator.
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 surface smoothness, glossy and glossy even when an overprint layer is formed on an electrophotographic print having an image portion having a thickness equivalent to the toner. It gives a certain overprint and can visually give an impression close to that of a conventional silver halide photographic print.
In addition, the photocurable coating composition of the present invention is excellent in non-tackiness and surface smoothness, gloss, gloss, and flexibility with little warpage, even for a toner image having a feather oil layer on the image surface. Image prints rich in color, and an overprint visually close to a silver salt photographic print can be obtained.

<An ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group>
The photocurable coating composition of the present invention (hereinafter also simply referred to as “coating composition”) is an ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group (hereinafter also referred to as “specific cyclic monomer”). .) As an essential component.
In the following description, “cyclic amide” refers to a compound having a structure in which both ends of an alkylene group are closed by amide (—CONH—) bonds. “Cyclic imide” refers to a compound having a structure in which both ends of an alkylene group are closed by imide (—CONHCO—) bonds. This alkylene group may be substituted, or an alicyclic or aromatic ring may be condensed.
The cyclic amide group refers to an n-valent residue obtained by removing n hydrogen atoms from the cyclic amide, and the cyclic imide group refers to an n-valent residue obtained by removing n hydrogen atoms from the cyclic imide. Here, n represents an integer of 1 or more, and is preferably 1 to 3.
The hydrogen atom to be removed is preferably a hydrogen atom bonded to a nitrogen atom of an amide bond or an imide bond.
In place of the removed hydrogen atom, at least one monovalent group having an ethylenically unsaturated group is bonded to a nitrogen atom or a carbon atom of the cyclic amide group, and "the ethylenically unsaturated compound having a cyclic amide group" Become. In addition, one or more monovalent groups having an ethylenically unsaturated group instead of the removed hydrogen atom are bonded to a nitrogen atom or a carbon atom of the cyclic imide group, and “an ethylenically unsaturated compound having a cyclic imide group” It becomes. Further, the monovalent group having an ethylenically unsaturated group is preferably bonded to a nitrogen atom.
Here, an arbitrary linking group may be present between the ethylenically unsaturated group and the nitrogen atom or carbon atom. This linking group is preferably an aliphatic group, preferably a divalent group having 2 to 10 carbon atoms composed of carbon and oxygen, and a divalent group having 4 to 6 carbon atoms. More preferably.
In general, an ethylenically unsaturated compound having a cyclic amide group has one or more ethylenically unsaturated groups in an n-valent residue obtained by removing n (n represents an integer of 1 or more) hydrogen atoms from the cyclic amide. It is formed by bonding n monovalent groups having a group.
In the present invention, an ethylenically unsaturated compound having a cyclic amide group is also referred to as a “specific amide monomer”, and an ethylenically unsaturated compound having a cyclic imide group is also referred to as a “specific imide monomer”.
Hereinafter, the “ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group (specific cyclic monomer)” which is a characteristic component in the present invention will be described in detail.

[Ethylenically unsaturated compound having a cyclic amide group]
The ethylenically unsaturated compound (specific amide monomer) having a cyclic amide group that can be used in the present invention is a compound having one or more ethylenically unsaturated bonds and one or more cyclic amide groups in the molecule. Can be used without restriction. That is, it may be monofunctional or polyfunctional.
In the present invention, the cyclic amide is preferably a carboxylic acid amide.
The cyclic amide group may have a heteroatom such as O, N or S in its skeleton, and O is preferred as the heteroatom. The cyclic amide group may have a substituent, and the substituents may be linked to form an aliphatic ring or an aromatic ring.

The ethylenically unsaturated bond that the specific amide monomer has is preferably a polymerizable unsaturated bond, and more preferably a radical polymerizable double bond.
Preferred functional groups containing a radical polymerizable double bond include, for example, (meth) acryloyloxy group, (meth) acrylamide group, allyl group, styryl group, vinyl group, etc., and curing of the photocurable coating composition From the viewpoint of sensitivity, a (meth) acryloyloxy group, a (meth) acrylamide group, or a vinyl group is preferable.

The number of amide rings present in the molecule of the specific amide monomer is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1. Moreover, when it has a some amide ring, a part of carbon which forms an amide ring skeleton may be shared, for example, amide rings may form the spiro ring structure.
In addition, the number of ethylenically unsaturated double bonds present in the molecule of the specific amide monomer, preferably the number of radically polymerizable unsaturated double bonds is preferably 1 to 3, from the viewpoint of imparting curability and surface smoothness. , More preferably 1. That is, the specific amide monomer is preferably monofunctional.

  When a plurality of cyclic amide groups and ethylenically unsaturated bonds are contained in the molecule, the types of cyclic amide groups and ethylenically unsaturated bonds in the same compound may be the same or different.

  In the present invention, the specific amide monomer is preferably a compound represented by the following formula (1).

In the formula (1), R ^{1 to} R ⁷ each independently represents a hydrogen atom or an organic group, and examples of the organic group include an alkyl group, an aryl group, an alkoxy group, and an aryloxy group. A linear or branched alkyl group is preferred. Moreover, these substituents may further have a substituent. Furthermore, R ^{1 to} R ⁷ may be bonded to each other to form a ring. The formed ring structure may be an aliphatic ring or an aromatic ring.
Further, when n is 2 or more, a plurality of R ⁴ are present. In this case, R ⁴ may be the same group or different groups. The same applies to R ⁵ .
Further, at least one of R ¹ to R ⁷ have an ethylenically unsaturated bond.

  Moreover, n in Formula (1) represents the integer of 1-6, it is more preferable that it is an integer of 1-5, More preferably, it is 2-4, Especially preferably, it is 2 or 3. That is, the cyclic amide group is preferably a 5- to 10-membered ring, more preferably a 5- to 9-membered ring, still more preferably a 6- to 8-membered ring, and particularly preferably a 6-membered ring or a 7-membered ring. It is. It is preferable because the Tg of the cured film tends to be increased by increasing the ring. However, when n exceeds 6, since the solubility of the material may be decreased, n is within the above range. It is preferable.

Further, in these structures, a hydrogen atom bonded to any one of R ^{1 to} R ⁷ or a carbon atom of an organic group is removed, and a (meth) acryloyl group or vinyl is bonded via an oxygen atom or a nitrogen atom. By bonding the group, a specific amide monomer is obtained.

  Among these, in the present invention, the specific amide monomer is more specifically a compound represented by the following formula (3) or formula (4), that is, an N (nitrogen) atom forming a ring skeleton of a cyclic amide group. A compound in which a group having an ethylenically unsaturated bond is bonded via a predetermined linking group is preferred.

Equation (3), (4), R ² to R ⁷ has the same meaning as R ² to R ⁷ in each formula (1), and preferred ranges are also the same.
R ⁸ and R ⁹ represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and are preferably a methyl group or a hydrogen atom.

  Z represents a divalent linking group or a single bond, and is an oxygen atom, -NH group, or an alkylene group having 1 or more carbon atoms, preferably an alkylene group having 1 to 20 carbon atoms, More preferably, it is 12 alkylene groups. As the alkylene group becomes longer, the steric hindrance in the vicinity of the polymerizable group (ethylenically unsaturated bond) decreases, so the reactivity of the polymerizable group improves, but when the number of carbons exceeds 20, the solubility of the material decreases. Therefore, the number of carbon atoms of the alkylene group is preferably within the above range.

The alkylene group represented by Z is selected from the group consisting of —C (═O) —, —O—, —S— and —NR ⁷ — in a methylene chain consisting of a methylene group (—CH ₂ —). One or more divalent groups may be included, and those having an ether bond (—O—) in an alkylene chain composed of a methylene group are preferable. Especially, what has an ether bond (-O-) in the terminal side couple | bonded with carbon of an alkylene group is especially preferable.
Here, R ⁷ is a hydrogen atom or an alkyl group having 1 or more carbon atoms, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, It is especially preferable that it is a C1-C4 alkyl group. More preferable examples of the alkyl group include a methyl group, an ethyl group, an n-butyl group, an n-hexyl group, and an n-nonyl group, and a methyl group, an ethyl group, and a butyl group are more preferable.

[Ethylenically unsaturated compound having a cyclic imide group]
Hereinafter, the “ethylenically unsaturated compound having a cyclic imide group (specific imide monomer)” which is one of the characteristic components in the present invention will be described in detail.
The ethylenically unsaturated compound (specific imide monomer) having a cyclic imide group that can be used in the present invention is a compound having one or more ethylenically unsaturated bonds and one or more cyclic imide groups in the molecule. Can be used without restriction. That is, it may be monofunctional or polyfunctional.
The cyclic imide group may have a heteroatom such as O, N, or S in its skeleton, and O (oxygen) is preferable as the heteroatom. In addition, the cyclic imide group may have a substituent, and the substituents may be linked to form an aliphatic ring or an aromatic ring.

The ethylenically unsaturated bond that the specific imide monomer has is preferably a polymerizable unsaturated bond, and more preferably a radical polymerizable double bond.
Preferred functional groups containing a polymerizable double bond include, for example, (meth) acryloyloxy group, (meth) acryloylamide group, allyl group, styryl group, vinyl group, and the like, from the viewpoint of curing sensitivity of the coating composition. To (meth) acryloyloxy group, (meth) acryloylamide group and vinyl group.

1-4 are preferable, as for the number of the imide rings which exist in the molecule | numerator of a specific imide monomer, More preferably, it is 1-2, Especially preferably, it is 1. Moreover, when it has a several imide ring, a part of carbon which forms an imide ring skeleton may be shared, for example, you may form the spiro ring structure.
Further, the number of ethylenically unsaturated bonds, preferably radical polymerizable unsaturated double bonds present in the molecule of the specific imide monomer is preferably 1 to 2, and the adhesion function is expressed and the flexibility of the formed film More preferably 1. That is, the specific imide monomer is preferably monofunctional.

  When a plurality of cyclic imide groups and ethylenically unsaturated bonds are contained in the molecule, the types of cyclic imide groups and ethylenically unsaturated bonds in the same compound may be the same or different.

  The specific imide monomer is preferably a compound represented by the following formula (2).

In the formula (2), R ^{1 to} R ⁵ each independently represents a hydrogen atom or an organic group, and examples of the organic group include an alkyl group, an aryl group, an alkoxy group, and an aryloxy group. A linear or branched alkyl group is preferred. Moreover, these substituents may further have a substituent. Further, R ^{1 to} R ⁵ may be bonded to each other to form a ring. The formed ring structure may be an aliphatic ring or an aromatic ring.
Further, when n is 2 or more, a plurality of R ⁴ are present. In this case, R ⁴ may be the same group or different groups. The same applies to R ⁵ .

  Moreover, n in Formula (2) represents the integer of 1-6, it is preferable that it is an integer of 1-5 especially, More preferably, it is 2-4. That is, the cyclic imide group is preferably a 5- to 10-membered ring, more preferably a 5- to 9-membered ring, and further preferably a 6- to 8-membered ring. It is preferable because the Tg of the cured film tends to be increased by increasing the ring. However, when n exceeds 6, the solubility of the material may decrease, so the carbon number of the alkylene group is in the above range. It is preferable to be within.

In these structures, a hydrogen atom bonded to any one of R ^{1 to} R ⁵ or a carbon atom of an organic group is removed, and a (meth) acryloyl group or vinyl is bonded via an oxygen atom or a nitrogen atom. A specific imide monomer is obtained by combining groups.

  In particular, in the present invention, the specific imide monomer is more specifically a compound represented by the following formula (5) or formula (6), that is, an N (nitrogen) atom that forms a ring skeleton of a cyclic imide group. A compound in which an ethylenically unsaturated bond is bonded via a predetermined linking group is preferable.

Equation (5), wherein (6), R ² to R ⁵ have the same meanings as R ² to R ⁵ in each formula (2), and preferred ranges are also the same.
R ⁸ and R ⁹ represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and are preferably a methyl group or a hydrogen atom.

  Z represents a divalent linking group or a single bond, and is an oxygen atom, -NH group, or an alkylene group having 1 or more carbon atoms, preferably an alkylene group having 1 to 20 carbon atoms, More preferably, it is 12 alkylene groups. As the alkylene group becomes longer, the steric hindrance in the vicinity of the polymerizable group (ethylenically unsaturated double bond) decreases, so that the reactivity of the polymerizable group improves. In some cases, the carbon number of the alkylene group is preferably within the above range.

A divalent group selected from the group consisting of —CO—, —O—, —S— and —NR ⁷ — in the methylene chain consisting of a methylene group (—CH ₂ —) in the alkylene group represented by Z. It may have one or more groups, and preferably has an ether bond (—O—) in an alkylene chain composed of a methylene group. Especially, what has an ether bond (-O-) in the terminal side couple | bonded with carbon of an alkylene group is especially preferable.
Here, R ⁷ is a hydrogen atom or an alkyl group having 1 or more carbon atoms, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, It is especially preferable that it is a C1-C4 alkyl group. More preferable examples of the alkyl group include a methyl group, an ethyl group, an n-butyl group, an n-hexyl group, and an n-nonyl group, and a methyl group, an ethyl group, and a butyl group are more preferable.

Hereinafter, specific examples (exemplary compounds) of specific cyclic monomers (specific amide monomers and specific imide monomers) in the present invention will be shown, but the present invention is not limited to these.
In the structural formulas showing the following exemplary compounds, R represents a hydrogen atom or a methyl group.

The content of the specific cyclic monomer in the photocurable coating composition of the present invention is the weight of the entire photocurable coating composition from the viewpoint of imparting suitability for surface smoothness (leveling property) and non-tackiness (surface tackiness suppression). Is preferably 10% by weight or more, more preferably in the range of 10 to 90% by weight, still more preferably in the range of 10 to 60% by weight, and in the range of 30 to 60% by weight. It is particularly preferred that it is most preferably in the range of 40-60% by weight.
Furthermore, it is preferable that the specific cyclic monomer in the photocurable overprint composition of the present invention accounts for 50% by weight or more based on the entire polymerizable monomer to be used.
Moreover, a specific cyclic monomer may be used by 1 type and may use 2 or more types.

<Other polymerizable compounds>
The photocurable coating composition of the present invention may contain other polymerizable compounds in addition to the specific cyclic monomer.
Examples of the polymerizable compound that can be used in the present invention include an ethylenically unsaturated compound (radical polymerizable compound) that does not have a cyclic amide group and a cyclic imide group, and a cationic polymerizable compound.

  The radically polymerizable compound that can be used in combination in the present invention is a compound having an ethylenically unsaturated bond capable of radical polymerization, and is preferably copolymerizable with a specific cyclic monomer, and has a cyclic amide group and a cyclic group in the molecule. Any compound that does not have any imide group and has at least one radically polymerizable ethylenically unsaturated bond may be used, including those having chemical forms such as monomers, oligomers, and polymers. . Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties. It is preferable to use two or more kinds in combination for controlling performance such as reactivity and physical properties.

Examples of the polymerizable compound having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and salts thereof, Examples thereof include radical polymerizable compounds such as anhydrides having a saturated group, (meth) acrylate, (meth) acrylamide, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.
The (meth) acrylate represents acrylate or methacrylate, and (meth) acrylamide represents acrylamide or methacrylamide. In the present invention, for example, a monofunctional (meth) acrylate compound represents a compound having only one (meth) acryloxy group, and further has an ethylenically unsaturated bond other than the (meth) acryloxy group. Also good.

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, propylene Glycol diacrylate, dipropylene glycol diacryl , Tripropylene glycol diacrylate, tetrapropylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester Acrylic acid derivatives such as acrylate, N-methylolacrylamide, diacetoneacrylamide, epoxy acrylate, lauryl acrylate, hexanediol diacrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, allyl methacrylate, glycerol Dil methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane Examples include methacryl derivatives such as trimethacrylate and 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, and triallyl trimellitate. , Yamashita Shinzo, “Cross-linking agent handbook” (1981, Taiseisha); Kato Kiyomi ed., “UV / EB curing handbrush” "Cook (raw material edition)" (1985, Polymer publication society); Radtech study edition, "Application and market of UV / EB curing technology", p. 79, (1989, CMC); Eiichiro Takiyama, Commercially available products described in “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun), or radically polymerizable or crosslinkable monomers, oligomers and polymers known in the industry can be used.
Among these, it is preferable to use tripropylene glycol diacrylate, lauryl acrylate, and hexanediol diacrylate.

  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 radically polymerizable compound used in combination. 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.
Of these vinyl ether compounds, divinyl ether compounds and trivinyl ether compounds are preferable from the viewpoints of curability, adhesion, and surface hardness, and divinyl ether compounds are 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 an “acrylate compound”), and a compound having neither a cyclic amide group nor a cyclic imide group is preferably used. 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, methoxypolyethylene glycol acrylate, tetramethylol 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 diacrylate , Phenoxypolyethylene 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, methoxydi Propylene glycol acrylate, ditrimethylolpropane tetraacrylate, Data triacrylate, hexamethylene diisocyanate urethane prepolymer, stearyl acrylate, isoamyl acrylate, isomyristyl acrylate, isostearyl acrylate, lactone-modified acrylate.

  The acrylate monomers listed here have high reactivity, low viscosity, and excellent adhesion to a printing substrate.

It is preferable that the coating composition of this invention contains a polyfunctional ethylenically unsaturated compound as an essential specific cyclic monomer or the other polymerizable compound which can be used together arbitrarily.
Moreover, when using a polyfunctional ethylenically unsaturated compound, it is preferable that it is 5 to 40 weight% with respect to the total weight of a coating composition as content of a polyfunctional ethylenically unsaturated compound, 10-30 More preferably, it is% by weight. Within the above range, the non-tackiness is excellent, and the coating composition has an appropriate viscosity, so that good surface smoothness can be obtained.

  In the present invention, in order to improve non-tackiness (surface tackiness suppression) and surface smoothness, a specific cyclic monomer and a polyfunctional ethylenically unsaturated compound having no cyclic amide group and cyclic imide group are used in combination. It is more preferable to use a specific cyclic monomer in combination with a polyfunctional (meth) acrylate monomer having no cyclic amide group and no cyclic imide group, and a monofunctional specific cyclic monomer, a cyclic amide group and a cyclic imide. It is more preferable to use in combination with a polyfunctional acrylate monomer having no group.

  Moreover, when using together the specific cyclic monomer and the polyfunctional ethylenically unsaturated compound which does not have a cyclic amide group and a cyclic imide group, content of the polyfunctional ethylenically unsaturated compound which does not have a cyclic amide group and a cyclic imide group Is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, based on the total weight of the coating composition. Within the above range, non-tackiness is excellent, and a viscosity suitable for the coating composition can be obtained.

  In the present invention, according to various purposes, in addition to the combination of a radical polymerizable compound and a radical polymerization initiator, together with these, a cationic polymerizable compound and a cationic polymerization initiator as shown below were used in combination. 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.
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.

<Photopolymerization initiator>
The coating composition of the present invention contains a photopolymerization initiator.
A known photopolymerization 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 external energy due to actinic radiation. Examples of the active radiation 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.

Examples of radical photopolymerization initiators that can be preferably used in the present invention include (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) thios. Compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen bond And (m) alkylamine compounds and the like.
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, the compound is 2 or less, and further preferably 0.1 or less.
Among these, preferable photopolymerization initiators include (a) aromatic ketones, (b) acylphosphine compounds, and (c) aromatic onium salt compounds.
The photoinitiator in this invention may be used individually by 1 type, and may use 2 or more types together.

The content of the photopolymerization initiator in the present invention is preferably 0.01 to 35% by weight, preferably 0.1 to 30% by weight based on the total amount of the specific cyclic monomer and other polymerizable compound used in combination. %, More preferably 0.5 to 30% by weight.
Moreover, when using a sensitizer described later, the photopolymerization initiator is preferably 200: 1 to 1: 200 in a weight ratio of photopolymerization initiator: sensitizer with respect to the sensitizer. It is more preferably 50: 1 to 1:50, and further preferably 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.
The above cationic polymerization initiators may be used alone or in combination of two or more.

<Sensitizer>
A sensitizer can be added to the coating composition of the present invention in order to promote the decomposition of the photopolymerization initiator by irradiation with actinic radiation.
The sensitizer absorbs specific actinic radiation and enters an electronically excited state. The sensitizer in an electronically excited state comes into contact with the photopolymerization initiator to cause actions such as electron transfer, energy transfer, and heat generation, thereby causing a chemical change of the photopolymerization initiator, that is, decomposition, radical, acid. Or it promotes the production of bases.
In addition, the sensitizer that can be used in the present invention is preferably a compound or an amount having a small influence of coloring or the like when the coating composition of the present invention is used for overprinting.
The content of the sensitizer in the present invention is preferably 0.001 to 5% by weight, more preferably 0.01 to 3% by weight, based on the total weight of the coating composition. With this addition amount, curability is improved and the influence of coloring is small.

The sensitizer may be a compound corresponding to the wavelength of actinic radiation that generates an initiating species in the photopolymerization initiator to be used, but considering that it is used for a curing reaction of a general coating composition. Examples of preferred sensitizers include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines (Eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, Squalium), coumarins (for example, 7-diethylamino-4-methylcoumarin), benzophenones (for example, benzophenone) and the like.

  More preferable examples of the sensitizer include compounds represented by the following formulas (II) to (VI).

In the formula (II), A ¹ represents a sulfur atom or NR ⁵⁰ , R ⁵⁰ represents an alkyl group or an aryl group, and L ² represents a non-nuclear group that forms a basic nucleus together with the adjacent A ¹ and the adjacent carbon atom. R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a monovalent non-metal atomic group, and R ⁵¹ and R ⁵² may be bonded to each other to form an acidic nucleus. W represents an oxygen atom or a sulfur atom.

In formula (III), Ar ¹ and Ar ² each independently represent an aryl group, and are linked via a bond with —L ³ —. Here, L ³ represents —O— or —S—. W is synonymous with that shown in Formula (II).

In the formula (IV), A ² represents a sulfur atom or NR ⁵⁹ , L ⁴ represents a nonmetallic atomic group that forms a basic nucleus in combination with adjacent A ² and a carbon atom, R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a monovalent nonmetallic atomic group, and R ⁵⁹ represents an alkyl group or an aryl group.

In formula (V), A ³ and A ⁴ each independently represent —S— or —NR ⁶² — or —NR ⁶³ —, wherein R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl group, substituted or Represents an unsubstituted aryl group, and L ⁵ and L ⁶ each independently represent a nonmetallic atomic group that forms a basic nucleus together with adjacent A ³ , A ^4, and adjacent carbon atoms, R ⁶⁰ , R Each ⁶¹ is independently a hydrogen atom or a monovalent nonmetallic atomic group, or can be bonded to each other to form an aliphatic or aromatic ring.

In the formula (VI), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent, and A ⁵ represents an oxygen atom, a sulfur atom or NR ⁶⁷ . R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁶⁷ and R ⁶⁴ , and R ⁶⁵ and R ⁶⁷ are each an aliphatic or aromatic ring. Can be combined to form

  Preferable specific examples of the compounds represented by formulas (II) to (VI) include those shown below.

<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 (Degussa silicon dioxide particles) and organic particles such as crosslinked polymethylmethacrylate (PMMA) are added to the coating composition of the present invention to intentionally reduce the surface gloss. A print layer or overprint can be formed.

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 ° C. 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 printing substrate to obtain a printed material, a step of applying the photocurable coating composition of the present invention on the printed material, and the photocurable coating composition. It is preferable to include a step of photocuring.
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. A step of transferring to a substrate 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 photocurable coating composition. It is more 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 a method for transferring the developed image to the printing substrate 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, offset gravure coaters, slot coaters, extrusion coaters, etc. It can be illustrated. 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 ^{1g / m 2 ~10g / m 2} , 3g / m 2 ~6g / m ² is more preferable.
The formation amount of the overprint layer in the overprint of the present invention, per unit area, it is preferably in the range of ^{1g / m 2 ~10g / m 2} , is 3g / m ² ~6g / m ² More preferred.

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 preferably 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.

The following components were stirred with a stirrer to obtain a photocurable overprint composition.
Example 1
The following components were stirred with a stirrer to obtain a photocurable overprint composition.
・ Specific cyclic monomer shown in Table 1 50% by weight
Tripropylene glycol diacrylate (Aldrich) 20% by weight
・ Lauryl acrylate (Wako Pure Chemical Industries, Ltd.) 10% by weight
・ Irgacure 907 (Ciba Specialty Chemicals) 15% by weight
・ Benzophenone (Tokyo Chemical Industry Co., Ltd.) 3% by weight
・ Polydimethylsiloxane (Aldrich) 2% by weight

  The obtained solventless photocurable coating composition of Example 1 was evaluated for performance by the following method.

<Evaluation of surface smoothness (leveling property)>
For electrophotographic prints output to double-sided coated paper with a digital printer (DC8000) manufactured by Fuji Xerox Co., Ltd., coated on one side with a film thickness of 5 g / m ² using a UV varnish coater (SG610V) manufactured by Shinano Kenshi Co., Ltd. Then, 120 mJ / cm ² exposure was performed at an illuminance of 1.0 W / cm ^2, an overprint sample was prepared, and the state of occurrence of vertical stripes on the surface of the coated printed material was visually evaluated. The evaluation criteria are shown below.
◎: No vertical stripes ○: Small vertical stripes are observed ×: Vertical stripes are observed

<Non-tackiness (surface stickiness suppression) evaluation>
It is 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 has 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 UV lamp (LC8) manufactured by Hamamatsu Photonics Co., Ltd., 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 △: Slight stickiness ×: Uncured surface

  As a result of evaluation by the above method, the photocurable coating composition of Example 1 had a surface smoothness of ◯ and an overprint non-tackiness of ◎.

(Examples 2 to 20 and Comparative Examples 1 to 9)
A photocurable coating composition was prepared in the same manner as in Example 1 except that the specific cyclic monomer was changed to the monomer described in Table 1, and then this was used to make an overprint. Evaluation was performed. The evaluation results are summarized in Table 1.

(Example 21)
The following components were stirred with a stirrer to obtain a photocurable coating composition.
・ Specific cyclic monomer 30% by weight
Tripropylene glycol diacrylate (Aldrich) 20% by weight
・ Lauryl acrylate 20% by weight
・ Hexanediol diacrylate (Aldrich) 10% by weight
・ IRGACURE 907 (Ciba Specialty Chemicals) 15% by weight
・ Benzophenone (Tokyo Chemical Industry Co., Ltd.) 3% by weight
・ Polydimethylsiloxane (Aldrich) 2% by weight

  The obtained photocurable coating composition of Example 21 and an overprint obtained using the same were produced, and performance evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.

(Examples 22 to 40 and Comparative Examples 10 to 18)
A photocurable coating composition and an overprint using the same were prepared in the same manner as in Example 21 except that the specific cyclic monomer was changed to the monomer described in Table 2, and performance evaluation was performed. . The evaluation results are shown in Table 2.

  In the table, OTA-480 and Blemmer PDT-800 are compounds having the structures shown below.

(Example 41)
Twenty printed materials were produced by electrophotographic printing full color images of several frames each on both sides of A4 size double side coated paper (basis weight 100 g / m ² ). The photocurable coating compositions prepared in Examples 1 to 40 were applied to both sides of these printed materials in the same manner as in Example 1 so that the coating amount was 5 g / m ^{2 on} one side. Thereafter, ultraviolet light was irradiated to prepare a double-sided overprint. When these were bound and used as a photo album together with the cover, a photo album with the same visibility as a silver halide photo print was obtained.

(Example 42)
Full-color images and texts including menu photos were printed on both sides of 10 sheets of approximately B4 size double-side coated paper (basis weight 100 g / m ² ). The photocurable coating compositions prepared in Examples 1 to 40 were applied to both sides of these printed materials in the same manner as in Example 1 so that the coating amount was 5 g / m ^{2 on} one side. Thereafter, ultraviolet light was irradiated to prepare a double-sided overprint. 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 (12)

An ethylenically unsaturated compound having a cyclic amide group and / or a cyclic imide group, and
A photocurable coating composition comprising a photopolymerization initiator. The photocurable coating composition according to claim 1, wherein the ethylenically unsaturated compound having a cyclic amide group is a compound represented by the formula (1).

Wherein ^(1), R 1 ~R ⁷ each independently represent a hydrogen atom or an organic group, n represents an integer of 0 to 6. Any one of R ^{1 to} R ⁷ has an ethylenically unsaturated bond.   In the said Formula (1), n is an integer of 2-4, The photocurable coating composition of Claim 2. The photocurable coating composition according to any one of claims 1 to 3, wherein the ethylenically unsaturated compound having a cyclic imide group is a compound represented by the formula (2).

Wherein (2), R ¹ ~R ⁵ each independently represent a hydrogen atom or an organic group, n represents an integer of 0 to 6. Any one of R ^{1 to} R ⁵ has an ethylenically unsaturated bond.   In the said Formula (2), n is an integer of 2-4, The photocurable coating composition of Claim 4.   The photocurable coating composition according to any one of claims 1 to 5, wherein the ethylenically unsaturated compound having the cyclic amide group and / or the cyclic imide group is a monofunctional ethylenically unsaturated compound.   The photocurable coating composition as described in any one of Claims 1-6 containing a polyfunctional ethylenically unsaturated compound.   The photocurable coating composition according to any one of claims 1 to 7, which has substantially no absorption in the visible region.   The photocurable coating composition according to any one of claims 1 to 8, which is used for overprinting.   The photocurable coating composition according to any one of claims 1 to 9, 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 1-10 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 10 on the electrophotographic printed material; and
A step of photocuring the photocurable coating composition.