JP5297619B2 - Resin composition for laser engraving, resin printing plate precursor for laser engraving, relief printing plate and method for producing relief printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition which has high sensitivity of laser engraving and can be used for a printing plate precursor capable of direct print making by means of laser engraving, to provide a printing plate precursor and a relief printing plate using the resin composition, and to provide a manufacturing method of the relief printing plate. <P>SOLUTION: The resin composition for laser engraving comprises a polymerizable compound (A) having at least one acetal portion and a binder polymer (B). The printing plate precursor and the relief printing plate using the resin composition are provided. Further, the method of manufacturing the relief printing plate is also provided. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a resin composition for laser engraving, a resin printing plate precursor for laser engraving, a relief printing plate, and a method for producing a relief printing plate.

As a method for forming a relief plate by forming irregularities on the surface, a photosensitive elastomer composition or a photosensitive resin composition is used, these compositions are exposed to ultraviolet light through an original film, and an image portion is selectively selected. The so-called “analog plate-making” method is well known in which an uncured portion is removed using a developer.
The photosensitive elastomer composition contains an elastomeric polymer such as a synthetic rubber as a carrier, and the resulting relief plate is flexible, so that it is called a flexographic plate.

  The flexographic plate is suitable for water-based inks, alcohol inks, ester inks and solventless UV inks using an ink vehicle that does not erode rubber. Since flexographic plates are flexible, they have printability on printed materials with large surface irregularities and low-strength packaging materials. However, since they are easily deformed by stress, it is necessary to reduce the printing pressure. On the other hand, the photosensitive resin composition uses a plastic resin (plastic) as a carrier. The resulting relief plate is hard and is called a resin relief (letter press), and is distinguished from a flexographic plate. A commercially available resin relief plate is a water development type or an alcohol development type, and contains a water-soluble resin or an alcohol-soluble resin, respectively. The ink mainly used is an oil-based ink using an ink vehicle that does not erode these resins, or a solventless UV ink. Since the resin relief printing plate is hard, it is possible to apply a strong printing pressure, and clear and sharp printing can be performed by thickening the ink.

In many cases, analog plate making requires an original film using a silver salt material, and thus requires production time and cost of the original film. Furthermore, since chemical processing is required for developing the original image film and processing of the development waste liquid is also required, there is a disadvantage in environmental hygiene.
As a technique for solving the problems associated with analog plate-making, a flexographic printing plate precursor having a laser-sensitive mask layer element capable of forming an image mask in situ on a photosensitive elastomer layer or a photosensitive resin layer, or Resin relief printing plate precursors have been proposed (see, for example, Patent Documents 1 and 2). In the plate making method of these original plates, laser irradiation is performed based on image data controlled by a digital device, an image mask is formed on the spot from a mask layer element, and thereafter, through an image mask as in analog plate making. This is a plate making method in which the photosensitive elastomer layer (or photosensitive resin layer) and the image mask are developed and removed by exposure to ultraviolet light, and is referred to as “mask CTP method” in the flexographic printing plate and resin relief printing industry. Although the mask CTP method solves the problems related to the production process of the original film described above, there is a problem related to the treatment of the waste liquid generated in the development of the photosensitive elastomer layer and the photosensitive resin layer. Furthermore, in the case of a flexographic plate, a chlorine-based solvent such as trichlorethylene is often used for development, which is disadvantageous in terms of work hygiene.

As a means for solving the problems related to the development process and development waste liquid, a so-called “thermal development method” has been proposed in which the photosensitive elastomer layer is heated and the uncured portion is softened and removed (see, for example, Patent Document 3). . Since this method does not use a developing solution, it is preferable in terms of work environment, and the development waste can be incinerated without the need for special separation processing. However, the heat development method has a problem that the development speed is remarkably slower than that of the solvent development method, so that the work efficiency is low and a complicated and expensive development facility is required.
As another means for solving the problems relating to the development process and the development waste liquid, many direct engraving plate making using a laser, so-called “direct engraving CTP method” has been proposed. The direct engraving CTP method literally engraves with a laser to form reliefs, and has the advantage that the relief shape can be freely controlled, unlike the relief formation using the original film. For example, it is possible to sculpt deeply a portion where the extracted character portion is reproduced on the printed matter, or sculpture with a shoulder so that the halftone dot is not collapsed by losing the printing pressure at the portion reproducing the fine halftone dot.

Patent Documents 4 to 6 disclose flexographic printing plate precursors capable of laser engraving or flexographic printing plates obtained by laser engraving. In these documents, a monomer is mixed with an elastomeric rubber as a binder, the mixture is cured by a thermal polymerization mechanism or a photopolymerization mechanism, and then laser engraving is performed to obtain a flexographic plate.
The problem of the direct engraving CTP method is that laser engraving is slow. In the mask CTP method, the thickness of the mask layer element to be ablated is about 1 to 10 μm, whereas in the direct engraving CTP method, it is necessary to engrave at least 100 μm in order to directly form a relief. It is. Therefore, some proposals have been made to improve the laser engraving sensitivity.
For example, a flexographic printing plate precursor for laser engraving containing an elastomer foam has been proposed (Patent Document 7). Engraving sensitivity is improved by using a foam having a low density. However, since it is a low-density material, there is a problem that strength as a printing plate is insufficient and printing durability is remarkably impaired.
For example, a flexographic printing plate precursor for laser engraving containing a microsphere encapsulating a hydrocarbon-based gas has been proposed (Patent Document 8). The engraving sensitivity is improved by a system in which the gas in the microsphere expands due to the heat generated by the laser, causing the material to be engraved to collapse. Since it is a material system containing bubbles, there is a problem that the strength as a printing plate tends to be insufficient. In addition, gas is more easily expanded by heat than solids, and even if a microsphere with a high thermal deformation start temperature is selected, volume change due to changes in external temperature is not avoided, and stability of thickness accuracy is required. Not suitable for use in printing plates.
For example, a resin relief printing plate for laser engraving containing a polymer filler having a ceiling temperature of less than 600 degrees K has been proposed (Patent Document 9). Engraving sensitivity is improved by adding a polymer filler with a low depolymerization temperature. However, if such a polymer filler is used, the surface of the printing plate precursor will be uneven, which will seriously affect printing quality. Will have an impact.

Japanese Patent No. 2773847 JP-A-9-171247 JP 2002-357907 A Japanese Patent No. 2846954 JP 11-338139 A JP-A-11-170718 JP 2000-318330 A US Patent Application Publication No. 2003/180636 JP 2000-168253 A

  An object of the present invention is to propose a resin composition that can be used for a printing plate precursor that has high engraving sensitivity with laser and can be directly made by laser engraving. Another object is to propose a resin printing plate precursor for laser engraving with high engraving sensitivity.

[1]
A resin composition for laser engraving, comprising at least a polymerizable monomer (A) having one or more acetal sites and a hydrophilic polymer containing a hydroxyethylene unit as a binder polymer (B).
[2]
The resin composition for laser engraving according to [1], comprising a photothermal conversion agent (C) capable of absorbing light having a wavelength of 700 to 1300 nm.
[3]
The resin composition for laser engraving according to [2], wherein the photothermal conversion agent (C) is carbon black.
[4]
The resin composition for laser engraving according to [2], wherein the photothermal conversion agent (C) is a cyanine compound and / or a phthalocyanine compound.
[5]
The resin composition for laser engraving according to any one of [1] to [4], further containing a sulfur atom-containing polymerizable compound.
[6]
The resin composition for laser engraving according to [5], wherein the hydrophilic polymer is a polyvinyl alcohol (PVA) derivative.
[7]
[1] A resin printing plate precursor for laser engraving, comprising a relief forming layer comprising the resin composition for laser engraving according to any one of [1] to [6].
[8]
[7] A method for producing a relief printing plate, comprising a step 1) of crosslinking the relief-forming layer according to [7] by light and / or heat and a step 2) of laser-engraving the crosslinked relief-forming layer.
[9]
The process 1) is a process for producing a relief printing plate as described in [8], wherein the relief forming layer is crosslinked by heat.
[10]
A relief printing plate produced by the method according to [8] or [9].
[11]
[8] The relief printing plate according to [10], wherein the relief-forming layer crosslinked by the method according to [9] has a thickness of 0.05 mm or more.
[12]
The relief printing plate according to [10] or [11], wherein the relief forming layer crosslinked by the method according to [8] or [9] has a Shore A hardness of 50 to 90 °.
The present invention relates to the above [1] to [12], but hereinafter, other matters (for example, the following 1) to 12)) are also described.
1) A resin composition for laser engraving, comprising at least a polymerizable compound (A) having one or more acetal moieties and a binder polymer (B).
2) The resin composition for laser engraving according to 1) above, which contains a photothermal conversion agent (C) capable of absorbing light having a wavelength of 700 to 1300 nm.
3) The resin composition for laser engraving according to 2) above, wherein the photothermal conversion agent (C) is carbon black.
4) The resin composition for laser engraving according to 2) above, wherein the photothermal conversion agent (C) is a cyanine compound and / or a phthalocyanine compound.
5) The resin composition for laser engraving according to any one of 1) to 4) above, wherein the binder polymer (B) contains a hydrophilic polymer containing a hydroxyethylene unit.
6) The resin composition for laser engraving according to 5) above, wherein the hydrophilic polymer is a polyvinyl alcohol (PVA) derivative.
7) A resin printing plate precursor for laser engraving, comprising a relief forming layer comprising the resin composition for laser engraving according to any one of 1) to 6) above.
8) Production of a relief printing plate comprising the step 1) of crosslinking the relief forming layer according to 7) above by light and / or heat and the step 2) of laser engraving the crosslinked relief forming layer. Method.
9) The method for producing a relief printing plate as described in 8) above, wherein the step 1) is a step of crosslinking the relief forming layer by heat.
10) A relief printing plate produced by the method described in 8) or 9) above.
11) The relief printing plate as described in 10) above, wherein the thickness of the relief-forming layer crosslinked by the method described in 8) or 9) is 0.05 mm or more.
12) The relief printing plate as described in 10) or 11) above, wherein the Shore A hardness of the relief-forming layer crosslinked by the method described in 8) or 9) is 50 to 90 °.

  According to the present invention, a resin composition for laser engraving having high engraving sensitivity to a laser can be obtained. For this reason, the time taken to form the relief can be shortened. Moreover, the resin printing plate precursor for laser engraving with high engraving sensitivity can be obtained by using the resin composition for laser engraving of the present invention. Although it can be used for a resin relief plate (letter press plate) having a convex relief, a flexographic plate, a stamp, an intaglio plate, and a stencil plate, its application range is not limited thereto.

Embodiments of the present invention will be described below.
[Resin composition for laser engraving]
The resin composition for laser engraving in the present invention contains at least a polymerizable compound (A) having one or more acetal sites and a binder polymer (B). Hereinafter, the elements of the resin composition for laser engraving will be described. Hereinafter, the resin composition for laser engraving of the present invention is also referred to as the resin composition of the present invention.

<(A) Polymerizable compound having one or more acetal moieties>
In the present invention, a polymerizable compound having an acetal moiety is used as a means for greatly improving the laser engraving sensitivity. Any polymerizable compound having an acetal moiety can be used without limitation.
In the present invention, the acetal moiety means a moiety containing an acetal bond.
As (A) in the present invention, an alcohol represented by the following general formula (A-1) or (A-2) is used as a raw material, and the polymerizable group-containing compound is (A-1) or (A-2). Those obtained by reacting with OH are preferred.

In formulas (A-1) and (A-2), R ₁ and R ₂ are each independently a divalent organic group which may have a substituent [for example, an alkyl group, an aralkyl group, an aryl group, Represents a divalent aliphatic hydrocarbon group, aromatic hydrocarbon group or heterocyclic group optionally having an alkoxy group, an aryloxy group, a halogen atom (—F, —Cl, —Br, —I), etc.] , R ₃ and R ₄ are each independently a hydrogen atom or a monovalent organic group which may have a substituent (for example, an alkyl group having 1 to 10 carbon atoms, an aralkyl group having 7 to 15 carbon atoms, carbon Represents an aryl group having 6 to 12 carbon atoms, preferably represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 15 carbon atoms, where the carbon number is It is also meant to include the number of carbon atoms of the substituent that may be present.
In the present invention, (A-2) is preferable in terms of laser decomposability and film properties of polyurethane obtained by using the diol as a raw material (details will be described later in the section of the binder polymer (B)).

The number of acetal sites in (A) is preferably 1 to 3, more preferably 1 or 2, and particularly preferably 1 from the viewpoint of combining sensitivity and film property.
The preferred content of the resin composition of (A) in the resin composition of the present invention is the total mass of the resin composition of the present invention from the viewpoint of enhancing the laser decomposition sensitivity and compatibility with the binder polymer constituting the film during pattern formation. When it is 100% by mass, it is preferably 1 to 95% by mass, more preferably 5 to 85% by mass, and particularly preferably 10 to 65% by mass.
The polymerizable group (A) may be any group that can cause any one of radical polymerization, cationic polymerization, anionic polymerization, and living polymerization. When used as a pattern forming material, it is preferably a radical polymerizable group in that the polymerization is hardly affected by the surrounding environment such as humidity.
Preferred radical polymerizable groups include (meth) acryloyl group, (meth) acrylamide group, styryl group, vinyl ether group and the like. A (meth) acryloyl group, a (meth) acrylamide group, and a styryl group are more preferable from the viewpoint of ease of compound synthesis, and a (meth) acryloyl group and a (meth) acrylamide group are more preferable in terms of imparting appropriate flexibility. In the present invention, the expression “(meth) acryloyl group” is a generic term for an acryloyl group and / or a methacryloyl group. In addition, the description which adds (meth) to acrylic acid and methacrylic acid, such as other (meth) acrylamide groups, (meth) acrylic acid, (meth) acrylate, and derivatives thereof is also the same.
The number of polymerizable groups in (A) is preferably 1 to 10 in the same molecule from the viewpoint of causing efficient polymerization, more preferably 2 to 6, and further preferably 2 to 4 Is the case.

Although the mechanism of action of the present invention is not clear, it is estimated as follows.
(A) The polymerizable compound having one or more acetal sites thermally decomposes at a relatively low temperature (less than 300 ° C.) with respect to (B) the binder polymer. As a result, (A) will be decomposed first, and the gas (such as carbon dioxide) generated when (A) is thermally decomposed and vaporized will assist in the scattering of the (B) pyrolyzate. To do. That is, (A) of the present application improves engraving sensitivity by two characteristics of being easily thermally decomposed (= easy to be laser decomposed) and assisting in the thermal decomposition and removal of the binder.
As a result, it is presumed that the film containing (A) has improved laser decomposability and engraving sensitivity compared to the polymerizable compound having no acetal moiety in the molecule and (B) the binder polymer alone.
In particular, when combined with a specific polyurethane as the binder polymer (B) described later, the specific polyurethane also thermally decomposes at a relatively low temperature, so the effect of the above (A) is expressed synergistically, and laser engraving dramatically. It is estimated that the sensitivity increases. Similarly, when combined with a hydrophilic polymer containing a hydroxyethylene unit (for example, polyvinyl alcohol (PVA) derivative) as a binder polymer (B) described later, a large number of OH groups in the binder and the acetal portion of (A) Therefore, the compatibility is improved and the function of assisting the thermal decomposition and removal of the binder is remarkably utilized. As a result, engraving sensitivity is increased.
In the present application, the binder polymer (B) is more preferably combined with a hydrophilic polymer containing a hydroxyethylene unit, and the hydrophilic polymer containing a hydroxyethylene unit is particularly preferably a PVA derivative.

  Hereinafter, preferred specific examples of (A) are shown below.

In the present invention, the polymerizable compound (A) having one or more acetal moieties can be used in combination with a known polymerizable compound.
Hereinafter, the case where an addition polymerizable compound is used as the polymerizable compound that can be used in combination will be described in detail.
Preferred polymerizable compounds used in the present invention include addition polymerizable compounds having at least one ethylenically unsaturated double bond. This addition polymerizable compound is preferably selected from compounds having at least one terminal ethylenically unsaturated bond, preferably two or more. Such a compound group is widely known in this industrial field, and in the present invention, these can be used without particular limitation. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or copolymers thereof, and mixtures thereof. Examples of monomers include unsaturated carboxylic acids (
For example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters thereof, and amides, preferably esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds. Amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds are used. In addition, unsaturated carboxylic acid ester having a nucleophilic substituent such as hydroxyl group, amino group, mercapto group, amide and monofunctional or polyfunctional isocyanate, addition reaction product of epoxy, monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. In addition, an unsaturated carboxylic acid ester having an electrophilic substituent such as an isocyanato group or an epoxy group, an addition reaction product of an amide with a monofunctional or polyfunctional alcohol, an amine or a thiol, a halogen group Also suitable are substitution reaction products of unsaturated carboxylic acid esters, amides with monofunctional or polyfunctional alcohols, amines, and thiols having a leaving substituent such as a tosyloxy group. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

  Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetracrotonate.

  Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.

  Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, Those having an aromatic skeleton described in JP-A-59-5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used.

  The ester monomers can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like.

  Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (V) to a polyisocyanate compound having two or more isocyanate groups. Compounds and the like.

_{CH 2 = C (R) COOCH} 2 CH (R ') OH (V)
(However, R and R ′ represent H or CH _3. )
Further, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable.

  Further, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, JP-A-1-105238 Can obtain a cured composition in a short time.

  Other examples include reacting polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191 and JP-B-52-30490. And polyfunctional acrylates and methacrylates such as epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid compounds described in JP-A-2-25493 are also included. be able to. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

From the viewpoint of photosensitive speed, a structure having a high unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable. Further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether type). A method of adjusting both photosensitivity and intensity by using a compound) is also effective. The addition polymerizable compound is used in an amount of preferably 10 to 60% by mass, more preferably 15 to 40% by mass, based on the nonvolatile components in the composition. These may be used alone or in combination of two or more. By using a polymerizable compound, film physical properties such as brittleness and flexibility can be adjusted.
Before and / or after laser decomposition, the resin composition for laser engraving containing a polymerizable compound can be polymerized and cured by energy such as light and heat.

  Preferred specific examples of the polymerizable compound used in the resin composition for laser engraving of the present invention are exemplified below.

Among the polymerizable compounds used in the present application, a compound containing a sulfur (S) atom is particularly preferable in that a relief relief is not easily generated and a sharp relief is easily obtained.
That is, it is preferable that an S atom is included in the crosslinked network.
Further, by using a plurality of S-containing polymerizable compounds having different characteristics, it is possible to contribute to the adjustment of the flexibility of the film.
Examples of the polymerizable compound containing an S atom include the following compounds.

<(B) Binder polymer>
Examples of the binder polymer (B) contained in the laser-decomposable resin composition of the present invention include polyurethane resins and acrylic resins. Hereinafter, the binder polymer (B) is also referred to as a binder (B).
As the polyurethane resin, those including the polyurethane described in JP-A-2005-250438 are preferable because of good film properties.
On the other hand, as acrylic resins, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, β-hydroxy -Β '-(meth) acryloyloxyethyl phthalate and other hydroxyl group-containing (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isoamyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, alkyl (meth) acrylate such as stearyl (meth) acrylate, cycloalkyl (meth) acrylate such as cyclohexyl (meth) acrylate , Alkoxyalkyl (meth) acrylates such as chloroethyl (meth) acrylate and chloropropyl (meth) acrylate, alkoxyalkyls such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate and butoxyethyl (meth) acrylate ( Phenoxyalkyl (meth) acrylates such as (meth) acrylate, phenoxyethyl acrylate, nonylphenoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, etc. Alkoxyalkylene glycol (meth) acrylate, (meth) acrylamide, diacetone (meth) acrylamide, N, N ′ (Meth) acrylamides such as methylenebis (meth) acrylamide, 2,2-dimethylaminoethyl (meth) acrylate, 2,2-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N A linear acrylic resin obtained by polymerizing a polymerizable compound having one ethylenically unsaturated bond in a molecule such as N, dimethylaminopropyl (meth) acrylamide.
As the polyurethane resin, those having the same acetal site as the polymerizable compound (A) having one or more acetal sites are preferable from the viewpoint of compatibility during film formation and molding.
As the polyurethane resin, a polyurethane resin represented by the following general formula (1) (hereinafter also referred to as a specific polyurethane resin) is preferable.

In General Formula (1), R ₁ and R ₂ each independently represent a divalent organic group. However, at least one of R ₁ and R ₂ is an aromatic group.

  The aromatic group in the general formula (1) is not particularly limited, but a phenylene group which may have a substituent or a naphthylene group which may have a substituent is preferable from the viewpoint of ease of synthesis. Particularly preferred is a phenylene group which may have a substituent. In particular, an electron-withdrawing substituent such as a phenylene group substituted with a carbonyl group, a halogen atom, a nitro group or the like is preferable.

Next, the basic skeleton of the specific polyurethane resin will be described. The specific polyurethane resin has a basic skeleton as a structural unit that is a reaction product of at least one diisocyanate compound represented by the following general formula (4) and at least one diol compound represented by the following general formula (5). The polyurethane resin.
OCN-X ⁰ -NCO (4)
HO-Y ⁰ -OH (5)

In general formulas (4) and (5), X ⁰ and Y ⁰ each independently represent a divalent organic residue. However, at least one of the organic residues represented by X ⁰ and Y ⁰ is bonded to the NCO group or OH group with an aromatic group.

(1) Diisocyanate Compound The diisocyanate compound represented by the general formula (4) preferably has an aromatic group in which the organic residue represented by X ⁰ is directly bonded to the NCO group.
A preferred diisocyanate compound is a diisocyanate compound represented by the following general formula (6).

OCN-L ¹ -NCO (6)

In General Formula (6), L ¹ represents a divalent aromatic hydrocarbon group which may have a substituent. Examples of the substituent include an alkyl group, an aralkyl group, an aryl group, an alkoxy group, an aryloxy group, and a halogen atom (—F, —Cl, —Br, —I). If necessary, L ¹ may have another functional group that does not react with an isocyanate group, such as an ester, urethane, amide, or ureido group.

Specific examples of the diisocyanate compound represented by the general formula (6) include those shown below. That is, 2,4-tolylene diisocyanate, 2,4-tolylene diisocyanate dimer, 2,6-tolylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate Aromatic diisocyanate compounds such as 1,5-naphthylene diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, and the like.
In particular, 4,4′-diphenylmethane diisocyanate and 1,5-naphthylene diisocyanate are preferable from the viewpoint of thermal decomposability.

The specific polyurethane resin used in the present invention uses, for example, a diisocyanate compound other than the above from the viewpoint of improving compatibility with other components in the laser-decomposable resin composition and improving storage stability. be able to.
Aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer diisocyanate, etc .; isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6 ) Alicyclic diisocyanate compounds such as diisocyanate and 1,3- (isocyanatomethyl) cyclohexane; reaction of diol and diisocyanate such as an adduct of 1 mol of 1,3-butylene glycol and 2 mol of tolylene diisocyanate The diisocyanate compound which is a product;
Further, diisocyanate obtained by adding a monofunctional alcohol to one of the three NCOs of triisocyanate can also be used.

(2) Diol Compound The diol compound preferably has an aromatic group in which the organic residue represented by Y ⁰ is directly bonded to the OH group.
Specifically, diol compounds represented by the following general formulas (A-1) to (A-3) are preferable.

HO—Ar ¹ —OH general formula (A-1)
HO— (Ar ¹ —Ar ² ) m—OH General formula (A-2)
HO—Ar ¹ —X—Ar ² —OH General Formula (A-3)

In the formula, Ar ¹ and Ar ² may be the same or different and each represents an aromatic ring. Examples of such an aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring, and a heterocyclic ring. These aromatic rings may have a substituent. Examples of the substituent include an alkyl group, an aralkyl group, an aryl group, an alkoxy group, an aryloxy group, and a halogen atom (—F, —Cl, —Br, —I).
From the viewpoint of easy availability of raw materials, a benzene ring and a naphthalene ring are preferable. A benzene ring is particularly preferable in consideration of film formability.
X is a divalent organic residue. m is preferably 1 to 3 from the viewpoint of film formation. Particularly preferred is 1.

Preferable examples of the diol compound represented by the general formula (A-1) include 1,4-dihydroxybenzene and 1,8-dihydroxynaphthalene.
Preferable examples of the diol compound represented by the general formula (A-2) include 4,4′-dihydroxybiphenyl and 2,2′-hydroxybinaphthyl.
Preferable examples of the diol compound represented by the general formula (A-3) include bisphenol A and 4,4′-bis (hydroxyphenyl) methane.

  As described above, the polyurethane resin includes an organic group including at least one of an ether bond, an amide bond, a urea bond, an ester bond, a urethane bond, a biuret bond, and an allophanate bond as a functional group in addition to the urethane bond. May be.

In particular, the specific polyurethane resin preferably further has a carbonate site and / or an acetal site in addition to the urethane bond.
When the specific polyurethane resin has a carbonate moiety, carbon dioxide gas derived from the thermal decomposition of the carbonate moiety is generated simultaneously with the thermal decomposition of the urethane bond in the main chain. As a result, it helps to disperse and remove decomposition products.
It is estimated that the laser decomposition sensitivity is improved and the laser engraving depth is increased.
The carbonate site only needs to be in one of the main chain and the side chain, and it is preferable to have the carbonate site in the main chain from the viewpoint of improving the laser decomposition sensitivity. The case where it has in a principal chain and a side chain is more preferable.
The production of a specific polyurethane resin containing a carbonate moiety can be considered in two forms: a form in which the raw material diisocyanate contains a carbonate part, and a form in which the raw material diol contains a carbonate part. May be. From the viewpoint of easy synthesis of raw materials, a form in which the diol includes a carbonate moiety is preferred.
In the specific polyurethane resin, the preferred content of the repeating unit containing a carbonate moiety is 0.1 to 50 mol% with respect to the total number of moles of raw materials constituting the specific polyurethane resin, from the viewpoint of maintaining good laser decomposition sensitivity and film property. More preferably, it is 5 to 50 mol%, particularly preferably 20 to 50 mol%.
Among the specific polyurethane resins, R ₁ and R ₂ in the general formula (1) both include a urethane bond that is an aromatic group (both adjacent to the urethane bond is an aromatic group), and have a carbonate moiety in the main chain. Are particularly preferred.
Preferable examples of the raw material for the specific polyurethane resin having a carbonate moiety include the above polycarbonate diol compounds.

On the other hand, when the specific polyurethane resin has an acetal site, the thermal decomposition efficiency as a whole of the specific polyurethane resin is improved because the specific polyurethane resin is thermally decomposed at the same time as or lower than the thermal decomposition of the urethane bond in the main chain. As a result, it is estimated that the laser decomposition sensitivity is improved and the laser engraving depth is increased.
The acetal moiety is preferably introduced into the main chain from the viewpoint of laser decomposability. For the production of a specific polyurethane resin containing an acetal moiety, there are two possible forms: a form in which the raw diisocyanate contains an acetal part, and a form in which the raw diol contains an acetal part. May be. From the viewpoint of easy synthesis of raw materials, a form in which the diol includes an acetal moiety is preferable.
In the specific polyurethane resin, the preferred content of the repeating unit containing an acetal moiety is 0.1 to 50 with respect to the total number of moles of raw materials constituting the specific polyurethane resin, from the viewpoint of maintaining good laser decomposition sensitivity and film property. It is preferable that it is mol%, More preferably, it is 5-50 mol%, Most preferably, it is 20-50 mol%.
Among the specific polyurethane resins, R ₁ and R ₂ in the general formula (1) both contain a urethane bond which is an aromatic group (both adjacent to the urethane bond are both aromatic groups), and have an acetal moiety in the main chain. Are particularly preferred.
The carbonate moiety-containing diol used as a raw material may be a chain or a ring.
Preferable examples of the raw material for the specific polyurethane resin having a carbonate moiety include an acetal diol compound.

The specific polyurethane resin used in the present invention preferably further has a unit having an ethylenically unsaturated bond.
As a method for introducing an ethylenically unsaturated bond into the side chain of the polyurethane resin, a method using a diol compound containing an ethylenically unsaturated bond in the side chain as a raw material for producing the polyurethane resin is also suitable. Such a diol compound may be a commercially available one such as trimethylolpropane monoallyl ether, or a carboxylic acid containing a halogenated diol compound, a triol compound, an aminodiol compound, and an ethylenically unsaturated bond. , An acid chloride, an isocyanate, an alcohol, an amine, a thiol, or a compound easily produced by a reaction with a halogenated alkyl compound.

When a polyurethane resin is synthesized under an NCO group-excess condition with an NCO / OH ratio of 1 or more, the end of the main chain is NC
Since it becomes an O group, an alcohol having an ethylenically unsaturated bond (2-hydroxyethyl (meth) acrylate, Blemmer PME200 (manufactured by Nippon Oil & Fats), etc.) is added separately and added to the end of the main chain to make it ethylenic. Unsaturated bonds can be introduced. In the present application, the main chain terminal may have an ethylenically unsaturated group in addition to the side chain.

The specific polyurethane resin is synthesized by adding the above-mentioned diisocyanate compound and diol compound to an aprotic solvent and adding a known catalyst having an activity corresponding to the respective reactivity, followed by heating. The molar ratio (M _a : M _b ) of the diisocyanate and diol compound used in the synthesis is preferably 1: 1 to 1.2: 1, and the molecular weight or viscosity is desired by treating with alcohols or amines. The product having the physical properties is finally synthesized in a form in which no isocyanate group remains.
Among them, the synthesis using a bismuth catalyst is preferable from the viewpoint of the environment and the polymerization rate than the tin catalyst that has been conventionally used. As such a bismuth catalyst, Neostan U-600 (trade name) (manufactured by Nitto Kasei) is particularly preferable.

Moreover, what has an ethylenically unsaturated bond in a polymer terminal and / or a polymer principal chain is also used suitably for the specific polyurethane resin which concerns on this invention.
As a method for introducing an unsaturated group into the polymer terminal, there are the following methods. That is, in the step of treating with the residual isocyanate group at the polymer end and the alcohols or amines in the above-mentioned polyurethane resin synthesis step, an alcohol or amine having an unsaturated group may be used.

  As a method for introducing an unsaturated group into a polymer main chain, there is a method of using a diol compound having an unsaturated group in the main chain direction for the synthesis of a polyurethane resin. Specific examples of the diol compound having an unsaturated group in the main chain direction include the following compounds. That is, cis-2-butene-1,4-diol, trans-2-butene-1,4-diol, polybutadiene diol, and the like.

The ethylenically unsaturated bond is preferably introduced into the polymer side chain rather than the polymer end from the viewpoint that the introduction amount can be easily controlled and the introduction amount can be increased, and the crosslinking reaction efficiency is improved.
The ethylenically unsaturated bond group to be introduced is preferably a methacryloyl group, an acryloyl group or a styryl group, more preferably a methacryloyl group or an acryloyl group, from the viewpoint of forming a crosslinked cured film. From the viewpoint of coexistence of the formability of the crosslinked cured film and the raw storage stability, a methacryloyl group is more preferable.

As an introduction amount of the ethylenically unsaturated bond contained in the specific polyurethane resin according to the present invention, in terms of equivalent, 0.3 meq / g or more of an ethylenically unsaturated bond group in the side chain, and further 0.35 to It is preferable to contain 1.50 meq / g. That is, a polyurethane resin containing 0.35 to 1.50 meq / g of methacryloyl group in the side chain is most preferable.
The molecular weight of the specific polyurethane resin according to the present invention is preferably 10,000 or more in terms of weight average molecular weight, and more preferably in the range of 40,000 to 200,000.
In particular, when the laser-decomposable resin composition of the present invention is used for the image recording layer of the pattern forming material, the strength of the image area is excellent when the weight average molecular weight is within this range.

  Specific examples of the specific polyurethane resin used in the present invention are shown below, but the present invention is not limited thereto.

  As the specific polyurethane combined with (A) of the present application, a combination with a specific polyurethane having a crosslinkable group in the side chain is particularly preferable.

On the other hand, when (A) of the present application is combined with a hydrophilic polymer containing a hydroxyethylene unit (for example, polyvinyl alcohol (PVA) derivative), many OH groups in the binder and the acetal part of (A) interact effectively. Therefore, the compatibility is improved, and the function of assisting the thermal decomposition and removal of the binder is remarkably utilized. As a result, engraving sensitivity is increased.
In this application, the case where the hydrophilic polymer containing a hydroxyethylene unit and (A) are combined as the binder (B) is more preferred, and the case where the hydrophilic polymer containing a hydroxyethylene unit is a PVA derivative is particularly preferred.

  Hereinafter, the hydrophilic polymer containing the hydroxyethylene unit will be described in detail. This hydrophilic polymer is also referred to as a hydrophilic polymer (B).

<< (B) hydrophilic polymer >>
As the hydrophilic polymer (B), one having resistance to oil-based ink is used. A hydrophilic polymer means a polymer that dissolves or swells in water. Hydrophilic resins are generally resistant to oil-based inks and are preferably used. Examples of such a resin include a polymer containing hydroxyethylene, a cellulose resin, an acrylic resin, and a polyamide resin into which a hydrophilic group such as polyethylene oxide is introduced.
Polymers containing hydroxyethylene, amino groups or carboxylic acid groups / sulfonic acid groups / sulfuric acid groups, and polar group-containing cellulose resins such as neutralized salt structures, amino groups, or carboxylic acids in terms of showing good hydrophilicity Acrylic resins and polyamide resins containing polar groups such as groups / sulfonic acid groups / sulfuric acid groups and salt structures in which these are neutralized are preferred.
More preferably, a hydrophilic polymer containing a hydroxyethylene unit, an amino group or a polar group such as a carboxylic acid group / sulfonic acid group / sulfuric acid group and a salt structure in which these are neutralized, an acrylic resin or a polyamide resin is preferable. Particularly preferred are polyvinyl alcohols and the above polyamide resins.

As the hydrophilic polymer, a PVA derivative is preferable. In the present invention, the PVA derivative means a copolymer containing 0.1 to 100 mol%, preferably 1 to 98 mol%, more preferably 5 to 95 mol% of a hydroxyethylene unit. It means a polymer or a polymer and a modified product thereof. Therefore, polyvinyl alcohol itself is also included. The monomer for forming the copolymer can be appropriately selected from known copolymerizable monomers. Examples of the modified body include those described below.
Particularly preferable examples of the PVA derivative include polyvinyl alcohol and vinyl alcohol / vinyl acetate copolymer (partially saponified polyvinyl alcohol), and these modified products also fall under this category.
A single polymer may be used as the hydrophilic polymer (B), or a plurality of types may be mixed and used.
As the hydrophilic polymer (B), it is particularly preferable to use a PVA derivative and a hydrophilic polymer not containing a hydroxyethylene unit in combination. The hydrophilic polymer containing no hydroxyethylene unit is also referred to as a non-PVA derivative.

The non-PVA derivative means one having a polarity close to the degree of compatibility with the PVA derivative.
Polyamide obtained by polymerization of only adipic acid, 1,6-hexanediamine, and ε-caprolactam is water-insoluble and clearly differs in polarity from PVA derivatives. A hydrophilic polyamide in which a hydrophilic group such as polyethylene glycol or piperazine is introduced into such a water-insoluble polyamide exhibits compatibility with the PVA derivative due to the action of the hydrophilic group, and is therefore used as a non-PVA derivative. It is suitable for. That is, since the hydrophilic polyamide used as the non-PVA derivative is compatible with the PVA derivative, it can easily enter between the molecules of the PVA derivative, and the action of the hydrophobic portion of the hydrophilic polyamide causes the PVA derivative and the non-PVA derivative to The intermolecular force between the two molecules is weakened, resulting in a softening of the polymer.
A polyamide having a polyethylene glycol unit is obtained by reacting ε-caprolactam and / or adipic acid with a polyethylene glycol modified with both terminal amines, and a hydrophilic polyamide having a piperazine skeleton is obtained by reacting with piperazine. Moreover, the hydrophilic polyamide by which the crosslinkable functional group was introduce | transduced into the polymer is obtained by making the amide group of hydrophilic polyamide react with the epoxy group of glycidyl methacrylate. These non-PVA derivatives may be used alone or in combination of two or more.

Examples of modified PVA derivatives include polymers in which at least some of the hydroxyl groups of the hydroxyethylene units are modified to carboxyl groups, polymers in which some of the hydroxyl groups are modified to (meth) acryloyl groups, and at least some of the hydroxyl groups are amino. Examples thereof include a polymer modified with a group, and a polymer in which ethylene glycol, propylene glycol and a multimer thereof are introduced into at least a part of the hydroxyl group.
A polymer in which at least a part of the hydroxyl group is modified to a carboxyl group can be obtained by esterification with polyvinyl alcohol or partially saponified polyvinyl alcohol and a polyfunctional carboxylic acid such as succinic acid, maleic acid or adipic acid. it can. The introduction amount of the carboxyl group is preferably 0.01 to 1.00 mol, more preferably 0.05 to 0.80 mol, relative to 1 mol of the hydroxyl group.
A polymer in which at least a part of the hydroxyl group is modified to a (meth) acryloyl group is obtained by adding glycidyl (meth) acrylate to the carboxyl group-modified polymer, or polyvinyl alcohol or partially saponified polyvinyl alcohol and (meth) acrylic acid, Can be obtained by esterification. The amount of (meth) acryloyl group introduced is preferably 0.01 to 1.00 mol, more preferably 0.03 to 0.50 mol, per mol of the hydroxyl group.
A polymer in which at least a part of the hydroxyl group is modified to an amino group can be obtained by esterification with polyvinyl alcohol or partially saponified polyvinyl alcohol and a carboxylic acid containing an amino group such as carbamic acid. The amount of amino group introduced is preferably 0.01 to 1.00 mol, more preferably 0.05 to 0.70 mol, per mol of the hydroxyl group.
A polymer in which ethylene glycol, propylene glycol, or a multimer thereof is introduced into at least a part of the hydroxyl group is obtained by heating polyvinyl alcohol or partially saponified polyvinyl alcohol and glycols under a sulfuric acid catalyst to remove water as a by-product. It can be obtained by removing it from the reaction system. The total amount of ethylene glycol, propylene glycol and their dimers introduced is preferably from 0.01 to 0.90 mol, more preferably from 0.03 to 0.50 mol, per mol of the hydroxyl group.

Among these modified products, a polymer obtained by modifying at least a part of the hydroxyl group to a (meth) acryloyl group is particularly preferably used. By directly introducing an unreacted crosslinkable functional group into the hydrophilic polymer (B), for example, without using a large amount of a polyfunctional monomer as an ethylenically unsaturated monomer described in the polymerizable compound (C) described later. This is because the strength of the relief forming layer can be increased and both the flexibility and strength of the relief forming layer can be achieved.
The mass average molecular weight (polystyrene conversion by GPC measurement) of the hydrophilic polymer (B) is preferably from 50,000 to 500,000. If the mass average molecular weight is 50,000 or more, the form retainability as a single resin is excellent, and if it is 500,000 or less, it is easy to dissolve in a solvent such as water, which is convenient for preparing a resin composition for laser engraving. is there. More preferably, it is 10,000 to 400,000, and particularly preferably 15,000 to 300,000.

The content of the hydrophilic polymer (B) in the resin composition for laser engraving is preferably 15% by mass to 79% by mass, and more preferably 30% by mass to 65% by mass with respect to the total mass of the solid content of the resin composition. When the content of the hydrophilic polymer (B) is 15% by mass or more, printing durability sufficient for use as a relief printing plate can be obtained, and when it is 79% by mass or less, other components may be insufficient. This is because flexibility sufficient for use as a flexographic printing plate can be obtained.
The total content when the PVA derivative and the non-PVA derivative are combined in the resin composition for laser engraving is preferably 30% by mass to 80% by mass, and 40% by mass to 70% by mass with respect to the total mass of the solid content of the resin composition. Is more preferable. By making the total content of the PVA derivative and the non-PVA derivative 30% by mass or more, it is possible to prevent cold flow of the original plate, and by making it 80% by mass or less, other components are not insufficient, This is because printing durability sufficient for use as a relief printing plate can be obtained.
In the combined use of the PVA derivative and the non-PVA derivative in the resin composition for laser engraving, the content of the PVA derivative is preferably 15% by mass to 79% by mass, and preferably 30% by mass to 65% by mass with respect to the total mass of the solid content of the resin composition. % Is more preferable. By setting the content of the PVA derivative to 15% by mass or more, printing durability sufficient for use as a relief printing plate can be obtained, and by setting it to 79% by mass or less, other components are not deficient in flexographic printing plates. This is because sufficient flexibility can be obtained. On the other hand, the content of the non-PVA derivative is preferably 1% by mass to 15% by mass and more preferably 3% by mass to 10% by mass with respect to the total mass of the solid content of the resin composition. By making the content of the non-PVA derivative 1% by mass or more, the softening of the PVA derivative is efficiently achieved and the flexibility sufficient for use as a flexographic plate is obtained, and the relief from the tough characteristics of the non-PVA derivative Printing durability sufficient to be used as a printing plate can be obtained, and by setting the content to 15% by mass or less, it is possible to reduce the amount of sticky engraving residue from which a non-PVA derivative is generated.

In the present application, it is possible to use a PVA derivative alone and a non-PVA derivative in combination, but from the viewpoint of ensuring suitability necessary for flexographic printing such as film flexibility and abrasion resistance, a PVA derivative and a non-PVA derivative are used. It is preferable to use a derivative together. The combination means may be a PVA derivative and a non-PVA derivative each alone, or one of them may be a plurality of types, or both may be a plurality of types.
In the present application, since the hydrophilic polymer (B) is used, the engraving residue is also hydrophilic, and as a result, the engraving residue can be removed by a simple operation of washing with tap water after engraving. Hydrophobic polymers and elastomers such as SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutylene-polystyrene), polyurethane, acrylic resin When slag is used as a main component binder, the engraving residue is hydrophobic, and it may be difficult to remove the engraving residue by washing with water.
For example, when a PVA derivative is used as the hydrophilic polymer (B) (particularly, the glass transition temperature is room temperature or higher), the glass transition temperature is higher than that of the above-described hydrophobic polymer or elastomer (mostly the glass transition temperature is room temperature or lower). Relief edge melting at the time of engraving due to its low tendency tends to be suppressed, which is preferable.

The hydrophilic polymer (B) may be used in combination with a relatively hydrophobic binder polymer as described above. As the relatively hydrophobic binder polymer, in order to adjust properties such as film hardness and flexibility at the time of film formation and compatibility with other components such as a polymerizable compound and an initiator, It is also possible to use a polymer containing a monomer as shown as a polymerization or copolymerization component.
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, β-hydroxy-β ′-(meth) (Meth) acrylate having a hydroxyl group such as acryloyloxyethyl phthalate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) Alkyl (meth) acrylates such as acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, chloroethyl (meth) Alkyl halides (meth) acrylates such as acrylate and chloropropyl (meth) acrylate, alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and butoxyethyl (meth) acrylate, phenoxyethyl acrylate , Alkoxyalkylene glycols (meth) such as phenoxyalkyl (meth) acrylates such as nonylphenoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate Acrylate, (meth) acrylamide, diacetone (meth) acrylamide, N, N′-methylenebis (meth) acryl (Meth) acrylamides such as amides, 2,2-dimethylaminoethyl (meth) acrylate, 2,2-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethyl Compounds having only one ethylenically unsaturated bond such as aminopropyl (meth) acrylamide, di (meth) acrylate of polyethylene glycol such as diethylene glycol di (meth) acrylate, such as dipropylene glycol di (meth) acrylate Polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol tri (meth) acrylate Such as polyvalent (meth) acrylates and glycidyl (meth) acrylates obtained by addition reaction of compounds with ethylenically unsaturated bonds and active hydrogen, such as unsaturated carboxylic acids and unsaturated alcohols, with ethylene glycol diglycidyl ether Polyhydric (meth) acrylamides such as polyvalent (meth) acrylates and methylenebis (meth) acrylamides obtained by the addition reaction of unsaturated epoxy compounds with compounds having active hydrogen such as carboxylic acids and amines, and many compounds such as divinylbenzene. And compounds having two or more ethylenically unsaturated bonds, such as a polyvalent vinyl compound. In this invention, these can be used individually or in combination of 2 or more types.

  From the viewpoint of film property, the monomer of the polymerization component is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytrile. Alkoxyalkylene glycol (meth) acrylates such as ethylene glycol (meth) acrylate and methoxydipropylene glycol (meth) acrylate, (meth) acrylamide, diacetone (meth) acrylamide, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, N -Acryloylmorpholine is preferred. Among these, acrylates are particularly preferable from the viewpoint of ensuring flexibility of the obtained polymer.

Other polymers that can be used in combination include the following.
Examples of the polymer include at least one of an olefin and a carbon-carbon triple bond in the main chain. For example, SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS ( Polystyrene-polyethylene / polybutylene-polystyrene) and the like.
The binder polymer that may be used in combination with the hydrophilic polymer (B) is preferably added to such an extent that the film property is improved without reducing the engraving sensitivity, and is preferably 1 to 50% by mass in the total binder polymer. More preferably, it is -30 mass%, and it is most preferable that it is 1-10 mass%.

In the present invention, the reason why the combination of the ionic liquid (A) and the hydrophilic polymer (B), in particular, the PVA derivative is particularly sensitive is presumed to the last. However, since the PVA derivative has many highly polar hydroxyl groups, That is, it is presumed to be very compatible with an ionic liquid having positive and negative charges and having a high polarity like PVA). As a result, the heat transfer to the PVA derivative to be thermally decomposed at the time of laser engraving is considered to be highly sensitive because it is efficiently performed.

  The resin composition of the present invention preferably contains a photothermal conversion agent (C), a polymerization initiator, a plasticizer and the like. These will be described in detail below.

<(C) Photothermal conversion agent>
The photothermal conversion agent (C) of the present invention has a maximum absorption wavelength at 700 to 1300 nm. In the resin composition for laser engraving of the present invention, when a laser (YAG laser, semiconductor laser, fiber laser, surface emitting laser, etc.) emitting infrared rays of 700 to 1300 nm is used for laser engraving as a light source, photothermal conversion is performed as an infrared absorber. Agent (C) is used. The photothermal conversion agent (C) absorbs laser light and generates heat to promote thermal decomposition of the resin composition. The photothermal conversion agent (C) used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 700 nm to 1300 nm.
As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, diimmonium compounds, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes And the like.
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59- 48187, JP-A 59-73996, JP-A 60-52940, JP-A 60-63744, etc., naphthoquinone dyes, JP-A 58-112792, etc. And cyanine dyes described in British Patent 434,875.
Also, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is preferably used, and a substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59-84248 Nos. 59-84249, 59-146063, 59-146061, pyranlium compounds, cyanine dyes described in JP-A-59-216146, US Pat. No. 4,283,475 The pentamethine thiopyrylium salts described above and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. . Moreover, as another example preferable as a dye, the near-infrared absorptive dye described as the formula (I) and (II) in US Patent 4,756,993 can be mentioned.

Other preferable examples of the photothermal conversion agent (C) of the present invention include specific indolenine cyanine dyes described in JP-A-2002-278057.
Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Furthermore, cyanine dyes and indolenine cyanine dyes are preferred.
Specific examples of cyanine dyes that can be suitably used in the present invention include paragraph numbers [0017] to [0019] of JP-A No. 2001-133969 and paragraph numbers [0012] to [0038] of JP-A No. 2002-40638. ], Paragraph number [
[0012] to [0023] can be mentioned.
The dye represented by the following general formula (d) or general formula (e) is preferable from the viewpoint of photothermal conversion.

In general formula (d), R ²⁹ to R ³¹ each independently represents a hydrogen atom, an alkyl group, or an aryl group. R ³³ and R ³⁴ each independently represents an alkyl group, a substituted oxy group, or a halogen atom. n and m each independently represents an integer of 0 to 4. R ²⁹ and R ³⁰ , or R ³¹ and R ³² may be bonded to each other to form a ring, and R ²⁹ and / or R ³⁰ are R ³³ and R ³¹ and / or R ³² is R ³⁴ taken together, may form a ring, further, when R ³³ or R ³⁴ there are a plurality, R ³³ or between R ³⁴ each other may be bonded to each other to form a ring. X ² and X ³ are each independently a hydrogen atom, an alkyl group, or an aryl group, and at least one of X ² and X ³ represents a hydrogen atom or an alkyl group. Q is a trimethine group or a pentamethine group which may have a substituent, and may form a ring structure together with a divalent organic group. Zc ^- represents a counter anion. However, Za ⁻ is not necessary when the dye represented by formula (d) has an anionic substituent in its structure and neutralization of charge is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion from the storage stability of the photosensitive layer coating solution, and particularly preferably a perchlorate ion, a hexagonal ion. Fluorophosphate ions and aryl sulfonate ions.

  In the present invention, specific examples of the dye represented by the general formula (d) that can be suitably used include those exemplified below.

In general formula (e), R ^{35 to} R ⁵⁰ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, aryl group, alkenyl group, alkynyl group, hydroxyl group, carbonyl group, thio group, sulfonyl group, sulfinyl. When a group, an oxy group, an amino group, or an onium salt structure is shown and a substituent can be introduced into these groups, it may have a substituent. M represents two hydrogen atoms or metal atoms, a halometal group, and an oxymetal group, and the metal atoms contained therein include IA, IIA, IIIB, IVB group atoms of the periodic table, first, second, second Three-period transition metals and lanthanoid elements can be mentioned, among which copper, magnesium, iron, zinc, cobalt, aluminum, titanium, and vanadium are preferable.

  In the present invention, specific examples of the dye represented by formula (e) that can be suitably used include those exemplified below.

Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.
Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.
These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. When the particle diameter of the pigment is 0.01 μm or more, the stability of the dispersion in the coating liquid increases, and when it is 10 μm or less, the uniformity of the resin composition layer is improved.
As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

Among these, a cyanine compound and a phthalocyanine compound are preferable in the present application because of high engraving sensitivity, and a cyanine compound and a phthalocyanine compound are particularly preferable. Furthermore, when used in a combination (condition) in which the thermal decomposition temperature of these photothermal conversion agents is equal to or higher than the thermal decomposition temperature of the hydrophilic polymer, the engraving sensitivity tends to be higher, which is preferable.
Specific examples of the photothermal conversion agent used in the present application include cyanine dyes such as heptamethine cyanine dyes, oxonol dyes such as pentamethine oxonol dyes, indolium dyes, benzindolinium dyes, benzothiazolium dyes Examples thereof include a dye, a quinolinium-based dye, and a phthalide compound reacted with a developer. Not all cyanine dyes have the light absorption characteristics described above. The light absorption characteristics vary greatly depending on the type of substituent and position in the molecule, the number of conjugated bonds, the type of counterion, the surrounding environment in which the dye molecule is present, and the like. Further, commercially available laser dyes, supersaturated absorbing dyes, and near infrared absorbing dyes can also be used. For example, as a laser dye, trade marks “ADS740PP”, “ADS745HT”, “ADS760MP”, “ADS740WS”, “ADS765WS”, “ADS745NH”, “ADS790NH”, “ADS800NH” of American Dye Source (Canada), Trademarks “NK-3555”, “NK-3509”, and “NK-3519” manufactured by Hayashibara Biochemical Laboratories, Inc. can be mentioned. In addition, as the near-infrared absorbing dyes, trade names “ADS775MI”, “ADS775MP”, “ADS775HI”, “ADS775PI”, “ADS775PP”, “ADS780MT”, “ADS780BP”, “ADS793EI”, trade names “ADS775MI”, “ADS775MP”, “ADS775HI” , “ADS798MI”, “ADS798MP”, “ADS800AT”, “ADS805PI”, “ADS805PP”, “ADS805PA”, “ADS805PF”, “ADS812MI”, “ADS815EI”, “ADS818HI”, “ADS818HT”, “ADS8” ADS830AT, ADS838MT, ADS840MT, ADS845BI, ADS905AM, ADS956BI, ADS1040T, “ADS1040P”, “ADS1045P”, “ADS1050P”, “ADS1060A”, “ADS1065A”, “ADS1065P”, “ADS1100T”, “ADS1120F”, “ADS1120P”, “ADS780WS”, “ADS785WS”, “ADS790WS”, “ADS790WS”, “ADS790WS” , "ADS820WS", "ADS830WS", "ADS850WS", "ADS780HO", "ADS810CO", "ADS820HO", "ADS821NH", "ADS840NH", "ADS880MC", "ADS890MC", Yamamoto Corporation , Trademarks “YKR-2200”, “YKR-2081”, “YKR-2900”, “YKR-2100”, “YKR-3071”, Arimoto Made by Manabu Industry Co., Ltd., trademark "SDO-1000B", Hayashibara Biochemical Laboratories Inc., trademark "NK-3508", mention may be made of the "NKX-114". However, it is not limited only to these. Further, as the phthalide compound reacted with the developer, those described in Japanese Patent No. 3271226 can be used. Further, a phosphoric acid ester metal compound such as a complex of a phosphoric acid ester and a copper salt described in JP-A-6-345820 and WO99 / 10354 pamphlet can also be used. Furthermore, it is also possible to use ultrafine particles having a light-absorbing property in the near-infrared region and having a number average particle diameter of preferably 0.3 μm or less, more preferably 0.1 μm or less, and further preferably 0.08 μm or less. Examples thereof include metal oxides such as yttrium oxide, tin oxide and / or indium oxide, copper oxide, and iron oxide, or metals such as gold, silver, palladium, and platinum. Furthermore, metal ions such as copper, tin, indium, yttrium, chromium, cobalt, titanium, nickel, vanadium, and rare earth ions are contained in fine particles such as glass having a number average particle size of 5 μm or less, more preferably 1 μm or less. What was added can also be used. In the case of a dye that reacts with the photosensitive resin composition and changes its light absorption wavelength, it can be contained in the microcapsule. In that case, the number average particle diameter of the capsule is preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 1 μm or less. A material obtained by adsorbing metal ions such as copper, tin, indium, yttrium, and a rare earth element to ion exchanger fine particles can also be used. The ion exchanger fine particles may be organic resin fine particles or inorganic fine particles. Examples of the inorganic fine particles include amorphous zirconium phosphate, amorphous zirconium silicophosphate, amorphous zirconium hexametaphosphate, layered zirconium phosphate, reticulated zirconium phosphate, zirconium tungstate, zeolite, and the like. Examples of organic resin fine particles include commonly used ion exchange resins and ion exchange cellulose.

On the other hand, as long as the dispersion stability of the composition is stable, carbon black can be used regardless of the classification according to ASTM and the use (for example, for color, for rubber, for dry battery, etc.). . Carbon black includes, for example, furnace black, thermal black, channel black, lamp black, acetylene black and the like. In order to facilitate dispersion, black colorants such as carbon black can be used as color chips or color pastes previously dispersed in nitrocellulose or a binder, if necessary. Such chips and pastes can be easily obtained as commercial products.
In the present application, it is also possible to use carbon black having a relatively low specific surface area and relatively low DBP absorption, and even finer carbon black having a large specific surface area.
Examples of suitable carbon blacks include Printex® U, Printex® A or Specialschwarz® 4 (from Degussa).
In the present application, in terms of improving engraving sensitivity by efficiently transferring heat generated by photothermal conversion to surrounding polymers and the like, the specific surface area is at least 150 m ² / g and the DBP number is at least 150 ml / 100 g. Carbon black is preferred.
This specific surface area is preferably at least 250, particularly preferably at least 500 m ² / g. The DBP number is preferably at least 200, particularly preferably at least 250 ml / 100 g. The carbon black described above may be acidic or basic carbon black. Carbon black (a2) is preferably basic carbon black. Of course, mixtures of different binders can also be used.
Suitable conductive carbon blacks having a specific surface area up to about 1500 m ² / g and a DBP number up to about 550 ml / 100 g are for example Ketjenluck® EC300J, Ketjenluck® EC600J (from Akzo), It is commercially available under the names Princex® XE (from Degussa) or Black Pearls® 2000 (from Cabot), Ketjen Black (manufactured by Lion).

  The concentration of the photothermal conversion agent added to the resin composition for laser engraving varies greatly depending on the molecular extinction coefficient inherent to the molecule, but it is in the range of 0.01 to 20% by mass of the total mass of the solid content of the resin composition. More preferably, it is 0.05-10 mass%, Most preferably, it is the range of 0.1-5 mass%.

<Polymerization initiator>
As the polymerization initiator, those known to those skilled in the art can be used without limitation. Specifically, for example, Bruce M. Monroe et al., Chemical Revue, 93, 435 (1993) and RSD Davidson, Journal of Photochemistry and biology A: Chemistry, 73.81 (1993); JPFaussier, "Photoinitiated Polymerization-Theory and Applications ": Rapra Review vol. 9, Report, Rapra Technology (1998); M. Tsunooka et al., Prog. Polym. Sci., 21, 1 (1996). FDSaeva, Topics in Current Chemistry, 156, 59 (1990); GGMaslak, Topics in Current Chemistry, 168, 1 (1993); HBShuster et al, JACS, 112,
6329 (1990); IDFEaton et al, JACS, 102, 3298 (1980) and the like are also known in the group of compounds that cause oxidative or reductive bond cleavage.

  Hereinafter, a specific example of a preferable polymerization initiator will be described in detail with respect to a radical polymerization initiator which is a compound that generates radicals by light and / or heat energy and initiates and accelerates a polymerization reaction with a polymerizable compound. Are not limited by these statements.

  In the present invention, preferred radical polymerization initiators include (a) aromatic ketones, (b) onium salt compounds, (c) organic peroxides, (d) thio compounds, (e) hexaarylbiimidazole compounds, (F) ketoxime ester compound, (g) borate compound, (h) azinium compound, (i) metallocene compound, (j) active ester compound, (k) compound having carbon halogen bond, (l) azo compound, etc. Is mentioned. Specific examples of the above (a) to (l) are given below, but the present invention is not limited to these.

(a) Aromatic ketones (a) Aromatic ketones preferred as the radical polymerization initiator used in the present invention include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” P. Fouassier, J. et al. F. Examples include compounds having a benzophenone skeleton or a thioxanthone skeleton described in Rabek (1993), p77-117. For example, the following compounds are mentioned.

  Among these, examples of particularly preferable (a) aromatic ketones include the following compounds.

(b) Onium Salt Compound Preferred examples of the (b) onium salt compound as the radical polymerization initiator used in the present invention include compounds represented by the following general formulas (1) to (3).

In formula (1), Ar ¹ and Ar ² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. (Z ² ) ⁻ represents a counter ion selected from the group consisting of halogen ion, perchlorate ion, carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion, and sulfonate ion, preferably perchloric acid Ions, hexafluorophosphate ions, and aryl sulfonate ions.

In Formula (2), Ar ³ represents an aryl group having 20 or less carbon atoms, which may have a substituent. (Z ³ ) ⁻ represents a counter ion having the same meaning as (Z ² ) ⁻ .

In formula (3), R ²³ , R ²⁴ and R ²⁵ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. (Z ⁴ ) ⁻ represents a counter ion having the same meaning as (Z ² ) ⁻ .

  Specific examples of onium salts that can be suitably used in the present invention include those described in paragraphs [0030] to [0033] of JP-A-2001-133969 previously proposed by the present applicant, Those described in paragraph numbers [0015] to [0046] of JP-A No. 2001-343742, JP-A No. 2002-148790, JP-A No. 2001-343742, JP-A No. 2002-6482, JP-A No. 2002-116539, Specific aromatic sulfonium salt compounds described in JP-A No. 2004-102031 can be exemplified.

(c) Organic peroxide Preferred as the radical polymerization initiator used in the present invention (c) Organic peroxide includes almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. Examples thereof include methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tertiarybutylperoxy) -3,3. 5-trimethylcyclohexane, 1,1-bis (tertiarybutylperoxy) cyclohexane, 2,2-bis (tertiarybutylperoxy) butane, tertiarybutyl hydroperoxide, cumene hydroperoxide, diisopropylbenze Hydroperoxide, parameter hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, ditertiary butyl peroxide, tertiary butyl Cumyl peroxide, dicumyl peroxide, bis (tertiarybutylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (tertiarybutylperoxy) hexane, 2,5-xanoyl peroxide, peroxy Succinic oxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, meta-toluoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxy Dicarbonate, dimethoxyisopropyl peroxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tertiary butyl peroxyacetate, tertiary butyl peroxypivalate, tertiary butyl peroxyneodecanoate, Tertiary butyl peroxyoctanoate, tertiary butyl peroxy-3,5,5-trimethylhexanoate, tertiary butyl peroxylaurate, tertiary carbonate, 3,3'4,4'-tetra- ( t-butylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-amylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-hexylperoxycarbonyl) benzophenone 3, 3'4 , 4'-tetra- (t-octylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (cumylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (p-isopropyl) Cumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogendiphthalate), carbonyldi (t-hexylperoxydihydrogendiphthalate), and the like.

  Among them, 3,3'4,4'-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-amylperoxycarbonyl) benzophenone, 3,3'4 4'-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-octylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (cumylper) Peroxyesters such as (oxycarbonyl) benzophenone, 3,3'4,4'-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, di-t-butyldiperoxyisophthalate are preferred.

(d) Thio compound (d) Thio compounds preferable as the radical polymerization initiator used in the present invention include compounds having a structure represented by the following general formula (4).

(Wherein R ²⁶ represents an alkyl group, an aryl group or a substituted aryl group, R ²⁷ represents a hydrogen atom or an alkyl group, and R ²⁶ and R ²⁷ are bonded to each other to form an oxygen, sulfur and nitrogen atom. (A group of nonmetallic atoms necessary to form a 5-membered to 7-membered ring which may contain a selected heteroatom.)
Specific examples of the thio compound represented by the general formula (4) include the following compounds.

(e) Hexaarylbiimidazole compounds (e) Hexaarylbiimidazole compounds preferable as the radical polymerization initiator used in the present invention include lophine dimers described in JP-B Nos. 45-37377 and 44-86516, for example, 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-bromophenyl) -4,4', 5,5'- Tetraphenylbiimidazole, 2,2'-bis (o, p-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,4' , 5,5'-tetra (m-methoxyphenyl) biimidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4 ', 5,5'-tetra Phenylbiimidazole, 2,2'-bis (o-nitrophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-methylphenyl) -4,4', Examples include 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, and the like.

(f) Ketooxime ester compound Preferred as the radical polymerization initiator (f) ketoxime ester compound used in the present invention is 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, 2-acetoxyiminopentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one , 3-p-toluenesulfonyloxyiminobutan-2-one, 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one, and the like.

(g) Borate Compound As an example of a preferable (g) borate compound as a radical polymerization initiator used in the present invention, a compound represented by the following general formula (5) can be given.

(Wherein R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ may be the same or different from each other, and each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, A substituted or unsubstituted alkynyl group or a substituted or unsubstituted heterocyclic group, R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ may be combined with each other to form a cyclic structure; Provided that at least one of R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ is a substituted or unsubstituted alkyl group (Z ⁵ ) ⁺ represents an alkali metal cation or a quaternary ammonium cation.)
Specific examples of the compound represented by the general formula (5) are described in US Pat. Nos. 3,567,453 and 4,343,891, European Patents 109,772 and 109,773. Examples include compounds and those shown below.

(h) Azinium Compound Preferred examples of the (h) azinium salt compound used as the radical polymerization initiator used in the present invention include JP-A Nos. 63-138345, 63-142345, and 63-142346. Examples include compounds having an N—O bond described in Japanese Utility Model Laid-Open Nos. 63-143537 and 46-42363.

(i) Metallocene Compound Preferred (i) metallocene compounds as radical polymerization initiators used in the present invention include those disclosed in JP 59-152396, JP 61-151197, JP 63-41484, and JP Examples thereof include titanocene compounds described in JP-A-2-249 and JP-A-2-4705, and iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.

  Specific examples of the titanocene compound include di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, and di-cyclopentadienyl-Ti-bis-2,3. 4,5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti- Bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4 -Difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-Ti- -2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyridin-1-yl) phenyl) titanium bis (cyclopentadienyl) bis [2,6-difluoro-3- (methylsulfonamido) phenyl] titanium, bis (cyclopentadi Enyl) bis [2,6-difluoro-3- (N-butylbialoyl-amino) phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (N-butyl- (4-chlorobenzoyl) ) Amino) phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (N-benzyl-2,2-dimethylpentanoyla) ) Phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (N- (2-ethylhexyl) -4-tolyl-sulfonyl) amino] phenyl] titanium, bis (cyclopentadienyl) ) Bis [2,6-difluoro-3- (N- (3-oxaheptyl) benzoylamino) phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (N- (3 6-dioxadecyl) benzoylamino) phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (trifluoromethylsulfonyl) amino] phenyl] titanium, bis (cyclopentadienyl) bis [2 , 6-Difluoro-3- (trifluoroacetylamino) phenyl] titanium, bis (cyclopentadienyl) bis [2 , 6-Difluoro-3- (2-chlorobenzoyl) amino] phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (4-chlorobenzoyl) amino] phenyl] titanium, bis ( Cyclopentadienyl) bis [2,6-difluoro-3- (N- (3,6-dioxadecyl) -2,2-dimethylpentanoylamino) phenyl] titanium, bis (cyclopentadienyl) bis [2, 6-difluoro-3- (N- (3,7-dimethyl-7-methoxyoctyl) benzoylamino) phenyl] titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (N-cyclohexylbenzoyl) Amino) phenyl] titanium, and the like.

(j) Active ester compound Preferred as the radical polymerization initiator used in the present invention (j) is an imide sulfonate compound described in JP-B-62-2223, JP-B-63-14340, JP-A-59-174831. And the active sulfonates described in No. 1.

(k) Compound Having Carbon Halogen Bond Preferred examples of the compound (k) having a carbon halogen bond as the radical polymerization initiator used in the present invention include the following general formulas (6) to (12).

(Wherein, X ² represents a halogen atom, Y ¹ is _{^{-C (X 2) 3, -NH}} 2, -NHR 38, -NR 38, represent -OR ^38. Wherein R ³⁸ represents an alkyl group, a substituted An alkyl group, an aryl group, or a substituted aryl group, and R ³⁷ represents —C (X ² ) ₃ , an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, or a substituted alkenyl group.

(However, R ³⁹ is an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aryl group, a substituted aryl group, a halogen atom, an alkoxy group, a substituted alkoxyl group, a nitro group, or a cyano group, and X ³ is a halogen atom. And n is an integer of 1 to 3.)

(However, R ⁴⁰ is an aryl group or a substituted aryl group, R ⁴¹ is a group or halogen shown below, and Z ⁶ is —C (═O) —, —C (═S) — or —SO _2- , X ³ is a halogen atom, and m is 1 or 2.)

(R ⁴² and R ⁴³ are an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aryl group or a substituted aryl group, and R ⁴⁴ is the same as R ³⁸ in the general formula (6).)

(Wherein, R ⁴⁵ is an optionally substituted aryl group or heterocyclic group, R ⁴⁶ is a trihaloalkyl group or trihaloalkenyl group having 1 to 3 carbon atoms, p is 1, 2 or 3.)

(Equation (10), .L ⁷ which represents a carbonylmethylene heterocyclic compound having a trihalogenomethyl group is a hydrogen atom or the ^{formula: CO- (R 47) q (} C (X 4) 3) at r substituent Q ² is a sulfur, selenium or oxygen atom, dialkylmethylene group, alkene-1,2-ylene group, 1,2-phenylene group or N—R group, and M ⁴ is a substituted or unsubstituted alkylene group or An alkenylene group or a 1,2-arylene group; R ⁴⁸ is an alkyl group, an aralkyl group or an alkoxyalkyl group; and R ⁴⁷ is a carbocyclic or heterocyclic divalent aromatic group. And X ⁴ is a chlorine, bromine or iodine atom and q = 0 and r = 1 or q = 1 and r = 1 or 2.)

(Formula (11) represents a 4-halogeno-5- (halogenomethylphenyl) oxazole derivative. X ⁵ is a halogen atom, t is an integer of 1 to 3, and s is an integer of 1 to 4. , R ⁴⁹ is a hydrogen atom or a CH _3-t X ⁵ _t group, R ⁵⁰ is s-valent optionally substituted unsaturated organic group.)

(Formula (12) represents a 2- (halogenomethylphenyl) -4-halogenoxazole derivative. X ⁶ is a halogen atom, v is an integer of 1 to 3, and u is an integer of 1 to 4. ,
R ⁵¹ is a hydrogen atom or a CH _3-v X ⁶ _v group, R ⁵² is an unsaturated organic group which may be substituted for u-valent. )
Specific examples of such a compound having a carbon-halogen bond include those described in Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969), such as 2-phenyl 4,6-bis (trichloromethyl) -S-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl)- S-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine, 2 -(2 ', 4'-dichlorophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6 -Bis (trichloromethyl) -S-triazine, 2-n-nonyl-4,6-bis (trichloromethyl) -S-triazine, 2- (α, α, β-trichloroethyl) -4,6 Bis (trichloromethyl) -S- triazine. In addition, compounds described in British Patent 1388492, for example, 2-styryl-4,6-bis (trichloromethyl) -S-triazine, 2- (p-methylstyryl) -4,6-bis (trichloromethyl) -S-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -S-triazine, 2- (p-methoxystyryl) -4-amino-6-trichloromethyl-S-triazine, etc. And compounds described in JP-A-53-133428, such as 2- (4-methoxy-naphth-1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (4-ethoxy-naphtho) 1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- [4- (2-ethoxyethyl) -naphth-1-yl] -4,6-bis-trick Rumethyl-S-triazine, 2- (4,7-dimethoxy-naphth-1-yl) -4,6-bis-trichloromethyl-S-triazine), 2- (acenaphtho-5-yl) -4,6- Examples include compounds described in German Patent No. 3333724, such as bis-trichloromethyl-S-triazine, and the like. Or even more P. Hutt, E .; F. Elslager and L.L. M.M. The following compounds that can be easily synthesized by those skilled in the art according to the synthesis method described in “Journalof Heterocyclic Chemistry”, Volume 7 (No. 3) by Herbel, page 511 et seq. (1970) Examples of the group include the following compounds.

(l) Azo-based compound Preferred as the radical polymerization initiator used in the present invention (l) As the azo-based compound, 2,2′-azobisisobutyronitrile, 2,2′-azobispropionitrile, 1 , 1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′- Azobis (4-methoxy-2,4-dimethylvaleronitrile), 4,4′-azobis (4-cyanovaleric acid), dimethyl 2,2′-azobisisobutyrate, 2,2′-azobis (2-methylpropionamide) Oxime), 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2- Hydro Cyethyl] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2 '-Azobis (N-cyclohexyl-2-methylpropionamide), 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (2,4,4- Trimethylpentane) and the like.

  As still more preferred examples of the radical polymerization initiator in the present invention, the above-mentioned (a) aromatic ketones, (b) onium salt compounds, (c) organic peroxides, (e) hexaarylbiimidazole compounds, ( i) metallocene compounds, (k) compounds having a carbon halogen bond, and most preferred examples include aromatic iodonium salts, aromatic sulfonium salts, titanocene compounds, and trihalo represented by the general formula (6). Mention may be made of methyl-S-triazine compounds.

The polymerization initiator is preferably added in a proportion of 0.01 to 10% by mass, more preferably 0.1 to 3% by mass, based on the total solid content of the resin composition for laser engraving containing a polymerizable compound. Can do.
The polymerization initiator in the present invention is suitably used alone or in combination of two or more.

<(F) Plasticizer>
Examples of the plasticizer include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, methyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, and triacetyl glycerin. Examples of the plasticizer include polyethylene glycols, polypropylene glycol (monool type and diol type), and polypropylene glycol (monool type and diol type).
A plasticizer has the effect | action which softens a relief forming layer, and needs to have a good compatibility with a binder (B). In general, a highly hydrophilic compound has good compatibility with the binder (B). Among the highly hydrophilic compounds, for example, those having a structure in which a hydrophilic group and a hydrophobic group are alternately continued, such as an ether compound containing a hetero atom in a straight chain or a secondary amine, are preferably used. This is because the presence of a hydrophilic group such as —O— or —NH— develops compatibility with the PVA derivative, and other hydrophobic groups weaken the intermolecular force of the PVA derivative and work to make it flexible. Further, those having a small number of hydroxyl groups capable of forming hydrogen bonds with the PVA derivative are preferably used. Such compounds include ethylene glycol, propylene glycol, and dimers, trimers, and single and multimers of tetramers and higher, 2 such as diethanolamine and dimethylolamine. Secondary amines. Among these, ethylene glycols (monomers, dimers, trimers, and multimers) that have low steric hindrance, excellent compatibility, and low toxicity are particularly preferably used as plasticizers.
Ethylene glycols are roughly classified into three types according to their molecular weights. The first is ethylene glycol as a monomer, the second is diethylene glycol as a dimer and the triethylene glycol as a trimer, and the third is a polyethylene glycol having a tetramer or higher. Polyethylene glycol is often marketed under the name with an average molecular weight at the end, and is broadly classified into liquid polyethylene glycol having a molecular weight of 200 to 700 and solid polyethylene glycol having a molecular weight of 1000 or more.
As a result of intensive studies, it was found that the lower the molecular weight of the plasticizer, the higher the effect of softening the resin. From this, ethylene glycol as the first group, diethylene glycol and triethylene glycol as the second group, and tetraethylene glycol (tetramer) included in the third group are particularly preferable. More preferable plasticizers are diethylene glycol, triethylene glycol, and tetraethylene glycol because they are low in toxicity and are excellent in handleability without extraction from the resin composition. A mixture of two or more of these is also preferably used.
The plasticizer can be added in an amount of 10% by mass or less based on the total mass of the resin composition for laser engraving.

<Additives for improving engraving sensitivity>
More preferably, nitrocellulose is added as an additive for improving engraving sensitivity. Since nitrocellulose is a self-reactive compound, it generates heat during laser engraving and assists in the thermal decomposition of the coexisting hydrophilic polymer. As a result, it is estimated that the engraving sensitivity is improved.
The type of nitrocellulose is not particularly limited as long as it is thermally decomposable, and may be any of RS (regular soluble) type, SS (spirit soluble) type and AS (alcohol soluble) type. The nitrogen content of the nitrocellulose is usually about 10 to 14% by mass, preferably 11 to 12.5% by mass, and more preferably about 11.5 to 12.2% by mass. The degree of polymerization of nitrocellulose can also be selected in a wide range of about 10 to 1500, for example. A preferable degree of polymerization of nitrocellulose is, for example, about 10 to 900, particularly about 15 to 150. Preferred nitrocellulose includes nitrocellulose having a solution viscosity of 20 to 1/10 seconds, preferably about 10 to 1/8 seconds, according to JIS K6703 “Industrial Nitrocellulose” (Hercules Powder Viscosity Indication Method). As nitrocellulose, nitrocellulose having a solution viscosity of 5 to 1/8 seconds, particularly about 1 to 1/8 seconds is often used. As the nitrocellulose for forming the resin composition for laser engraving, an RS type nitrocellulose that is soluble in esters such as ethyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and ethers such as cellosolve (for example, Nitrocellulose having a nitrogen content of about 11.7 to 12.2% is often used. Nitrocellulose may use 2 or more types together as needed.
The amount of nitrocellulose used can be selected within a range that does not reduce the sensitivity of the resin composition for laser engraving. For example, it is preferably 5 to 300 parts by weight, preferably 100 parts by weight of the binder (B) and the polymerizable compound (A). Is about 20 to 250 parts by mass, more preferably about 50 to 200 parts by mass, often about 40 to 200 parts by mass.

<Co-sensitizer>
By using a certain kind of additive (hereinafter referred to as a co-sensitizer), the sensitivity at the time of photocuring the resin composition for laser engraving can be further improved. These mechanisms of action are not clear, but many are thought to be based on the following chemical processes. That is, a co-sensitizer reacts with various intermediate active species (radicals and cations) generated in the process of a photoreaction initiated by a photopolymerization initiator and a subsequent addition polymerization reaction to generate new active radicals. It is estimated to be. These can be broadly divided into (a) those that can be reduced to generate active radicals, (b) those that can be oxidized to generate active radicals, and (c) radicals that are more active by reacting with less active radicals. Can be categorized as those that act as chain transfer agents, but often there is no generality as to which of these individual compounds belong.

(a) Compound that is reduced to produce an active radical Compound having a carbon-halogen bond: It is considered that an active radical is generated by reductive cleavage of the carbon-halogen bond. Specifically, for example, trihalomethyl-s-triazines and trihalomethyloxadiazoles can be preferably used.

  Compound having nitrogen-nitrogen bond: It is considered that the nitrogen-nitrogen bond is reductively cleaved to generate an active radical. Specifically, hexaarylbiimidazoles and the like are preferably used.

  Compound having oxygen-oxygen bond: It is considered that the oxygen-oxygen bond is reductively cleaved to generate an active radical. Specifically, for example, organic peroxides are preferably used.

Onium compound: An active radical is considered to be generated by reductive cleavage of a carbon-hetero bond or oxygen-nitrogen bond. Specifically, for example, diaryliodonium salts, triarylsulfonium salts, N-alkoxypyridinium (azinium) salts and the like are preferably used. Ferrocene and iron arene complexes: An active radical can be reductively generated.
(b) Compound that is oxidized to generate an active radical Alkylate complex: It is considered that an active radical is generated by oxidative cleavage of a carbon-hetero bond. Specifically, for example, triarylalkyl borates are preferably used.

  Alkylamine compound: It is considered that the C—X bond on carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical. X is preferably a hydrogen atom, a carboxyl group, a trimethylsilyl group, a benzyl group or the like. Specific examples include ethanolamines, N-phenylglycines, N-trimethylsilylmethylanilines, and the like.

  Sulfur-containing and tin-containing compounds: Compounds in which the nitrogen atoms of the above-described amines are replaced with sulfur atoms and tin atoms can generate active radicals by the same action. Further, a compound having an SS bond is also known to be sensitized by SS cleavage.

  α-Substituted methylcarbonyl compound: An active radical can be generated by oxidative cleavage of the carbonyl-α carbon bond. Moreover, what converted carbonyl into the oxime ether also shows the same effect | action. Specifically, after reacting 2-alkyl-1- [4- (alkylthio) phenyl] -2-morpholinopronone-1 and these with a hydroxyamine, N-OH was etherified. Oxime ethers can be listed.

Sulfinic acid salts: An active radical can be reductively generated. Specific examples include arylsulfin sodium.
(c) Compounds that react with radicals to convert into highly active radicals or act as chain transfer agents: For example, a group of compounds having SH, PH, SiH, GeH in the molecule is used. These can generate hydrogen by donating hydrogen to a low-activity radical species to generate radicals, or after being oxidized and deprotonated. Specific examples include 2-mercaptobenzthiazoles, 2-mercaptobenzoxazoles, 2-mercaptobenzimidazoles and the like.

  More specific examples of these co-sensitizers are described, for example, in JP-A-9-236913 as additives for the purpose of improving sensitivity, and these are also applied in the present invention. be able to. Some examples are shown below, but the present invention is not limited thereto. In the following formulae, -TMS represents a trimethylsilyl group.

  As with the photothermal conversion agent (C), the co-sensitizer can also be subjected to various chemical modifications for improving the properties of the resin composition for laser engraving. For example, photothermal conversion agent (C), polymerizable compound (A), bonding with other parts, introduction of hydrophilic sites, compatibility improvement, introduction of substituents for suppressing crystal precipitation, substituents for improving adhesion Methods such as introduction and polymerization can be used.

  A co-sensitizer can be used individually or in combination of 2 or more types. The amount used is 0.05 to 100 parts by weight, preferably 1 to 80 parts by weight, and more preferably 3 to 50 parts by weight with respect to 100 parts by weight of the polymerizable compound (A).

<Polymerization inhibitor>
In the present invention, in addition to the above components, it is desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the polymerizable compound (A) during the production or storage of the composition. Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. In addition, as a polymerization inhibitor, a resin printing plate precursor for laser engraving having a relief forming layer using the resin composition according to the present invention is created, in that it is very excellent in stability when stored, Q-1301 (10% tricresyl phosphate solution) (manufactured by Wako Pure Chemical Industries) is preferred. When this is used in combination with the polymerizable compound (A), the storage stability of the resin printing plate precursor for laser engraving is remarkably excellent and good laser engraving sensitivity can be obtained. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the total resin composition for laser engraving. If necessary, higher fatty acid derivatives such as behenic acid and behenic acid amide are added to inhibit polymerization inhibition by oxygen, and the surface of the layer is dried during the coating process on the support. It may be unevenly distributed. The amount of the higher fatty acid derivative added is preferably about 0.5% by mass to about 10% by mass of the total composition.

<Colorant>
Further, a coloring agent such as a dye or a pigment may be added for the purpose of coloring the resin composition for laser engraving. Thereby, properties such as the visibility of the image portion and the suitability of the image density measuring device can be improved. As the colorant, it is particularly preferable to use a pigment. Specific examples include pigments such as phthalocyanine pigments, azo pigments, carbon black and titanium oxide, and dyes such as ethyl violet, crystal violet, azo dyes, anthraquinone dyes, and cyanine dyes. The amount of the colorant added is preferably about 0.5% to about 5% by weight of the total composition.

<Other additives>
Furthermore, in order to improve the physical properties of the cured film of the resin composition for laser engraving, a known additive such as a filler may be added.

  Examples of the filler include carbon black, carbon nanotube, fullerene, graphite, silica, alumina, aluminum, calcium carbonate, and the like, and are used alone or as a mixture thereof.

[Resin printing plate precursor for laser engraving]
The resin printing plate precursor for laser engraving in the present invention has a relief forming layer made of the resin composition for laser engraving of the present invention on a support. When a crosslinkable resin composition is used as the resin composition for laser engraving, a crosslinkable relief forming layer is obtained. If necessary, the resin printing plate precursor for laser engraving may further have an adhesive layer between the support and the relief forming layer, and a slip coat layer and a protective film on the relief forming layer.
The resin printing plate precursor for laser engraving of the present invention can produce a relief printing plate by crosslinking the relief forming layer and then laser engraving. By crosslinking the relief forming layer, wear of the relief forming layer during printing can be prevented, and a relief printing plate having a sharp shape after laser engraving can be obtained.

The content of the binder (B) in the relief forming layer is preferably 30 to 80% by mass and more preferably 40 to 70% by mass with respect to the total solid content of the relief forming layer. By making the content of the binder (B) 30% by mass or more, it is possible to prevent cold flow of the original plate, and by making it 80% by mass or less, other components are not deficient, and as a relief printing plate This is because printing durability sufficient for use is obtained.
The content of the polymerization initiator in the relief forming layer is preferably 0.01 to 10% by mass and more preferably 0.1 to 3% by mass with respect to the total mass of the solid content of the relief forming layer. By setting the content of the polymerization initiator to 0.01% by mass or more, the crosslinkable relief forming layer is rapidly crosslinked, and by setting it to 10% by mass or less, other components are not insufficient, and the relief printing plate This is because the printing durability sufficient to be used as is obtained.
The content of the polymerizable compound (A) in the relief forming layer is preferably 10 to 60% by mass and more preferably 15 to 40% by mass with respect to the total mass of the solid content of the relief forming layer. Printing durability sufficient for use as a relief printing plate is obtained by setting the content of the polymerizable compound (A) to 10% by mass or more, and strength sufficient for use as a relief printing plate by setting the content to 60% by mass or less. Is obtained.
The relief forming layer can be obtained by molding the resin composition into a sheet shape or a sleeve shape.

Although the raw material used for the support of the resin printing plate precursor for laser engraving in the present invention is not particularly limited, a material having high dimensional stability is preferably used. For example, a metal such as steel, stainless steel, aluminum, polyester (for example, PET, PBT, PAN), plastic resins such as polyvinyl chloride, synthetic rubbers such as styrene-butadiene rubber, and plastic resins reinforced with glass fibers (such as epoxy resins and phenol resins). As the support for the relief printing plate, a PET (polyethylene terephthalate) film or a steel substrate is preferably used. The form of the support is determined depending on whether the relief forming layer is a sheet or a sleeve.
An adhesive layer may be provided between the relief forming layer and the support for the purpose of enhancing the adhesive force between the two layers. The material used for the adhesive layer may be any material that strengthens the adhesive force after the relief forming layer is crosslinked, but it is preferable that the adhesive force is strong even before the relief forming layer is crosslinked. Here, the adhesive force means both the adhesive force between the support / adhesive layer and the adhesive layer / relief forming layer.
When the adhesive layer and the relief forming layer are peeled from the laminate comprising the support / adhesive layer / relief forming layer at a rate of 400 mm / min, the peeling force per 1 cm width of the sample is 1 It is preferably 0.0 N / cm or more or non-peelable, and more preferably 3.0 N / cm or more or non-peelable.
The adhesive force of the adhesive layer / relief forming layer is such that when the adhesive layer is peeled from the adhesive layer / relief forming layer at a rate of 400 mm / min, the peel force per 1 cm width of the sample is 1.0 N / cm or more or cannot be peeled off. Preferably, it is 3.0 N / cm or more or more preferably non-peelable.

The relief forming layer becomes a part where the relief is formed after laser engraving, and the relief surface functions as an ink deposit part. Since the relief forming layer after cross-linking is reinforced by cross-linking, the surface of the relief forming layer hardly causes scratches or dents that affect printing. However, the relief forming layer before cross-linking is often insufficient in strength, and the surface is likely to have scratches and dents. For the purpose of preventing scratches and dents on the surface of the relief forming layer, a protective film may be provided on the surface of the relief forming layer.
If the protective film is too thin, the effect of preventing scratches and dents cannot be obtained. If the protective film is too thick, handling becomes inconvenient and the cost increases. Therefore, the thickness of the protective film is preferably 25 μm to 500 μm, and more preferably 50 μm to 200 μm.

As the protective film, a known material as a protective film for a printing plate, for example, a polyester film such as PET (polyethylene terephthalate), or a polyolefin film such as PE (polyethylene) or PP (polypropylene) can be used. The surface of the film may be plain or matted.
When providing a protective film on a relief forming layer, the protective film must be peelable. When the protective film cannot be peeled or when it is difficult to adhere to the relief forming layer, a slip coat layer may be provided between both layers.
The material used for the slip coat layer is a resin that is soluble or dispersible in water, such as polyvinyl alcohol, polyvinyl acetate, partially saponified polyvinyl alcohol, hydroxyalkyl cellulose, alkyl cellulose, polyamide resin, etc. It is preferable that Among these, partially saponified polyvinyl alcohol having a saponification degree of 60 to 99 mol%, hydroxyalkyl cellulose having 1 to 5 carbon atoms in the alkyl group, and alkyl cellulose are particularly preferably used from the viewpoint of tackiness.

When the protective film is peeled from the relief forming layer (and slip coat layer) / protective film at a speed of 200 mm / min, the peel force per 1 cm is preferably 5 to 200 mN / cm, more preferably 10 to 150 mN / cm. preferable. If it is 5 mN / cm or more, it can work without peeling off the protective film during the work, and if it is 200 mN / cm or less, the protective film can be peeled without difficulty.
Next, a method for producing a resin printing plate precursor for laser engraving will be described. The production method is not particularly limited, and examples thereof include a method of preparing a solution of a resin composition for laser engraving, removing the solvent from the solution, and then melt-extruding the solution on a support. Alternatively, a method of casting a solution of the resin composition for laser engraving on a support and drying it in an oven to remove the solvent from the solution may be used.
Thereafter, a protective film may be laminated on the relief forming layer as necessary. Lamination can be performed by pressure-bonding the protective film and the relief forming layer with a heated calendar roll or the like, or by bringing the protective film into close contact with the relief forming layer impregnated with a small amount of solvent on the surface.
When using a protective film, you may take the method of laminating | stacking a relief forming layer on a protective film first, and laminating a support body then.
When providing an adhesive layer, it can respond by using the support body which apply | coated the adhesive layer. When providing a slip coat layer, it can respond by using the protective film which apply | coated the slip coat layer.

The solution of the resin composition for laser engraving can be produced, for example, by dissolving the binder (B) and optionally a plasticizer in an appropriate solvent, and then dissolving the polymerization initiator and the polymerizable compound (A). Since most of the solvent components need to be removed at the stage of producing the printing plate precursor, it is preferable to use a low molecular alcohol (e.g., ethanol) that easily volatilizes and to keep the total amount of solvent added as small as possible. By increasing the temperature of the system, the amount of solvent added can be suppressed. However, if the temperature is too high, the polymerizable compound (A) is likely to undergo a polymerization reaction, so that the polymerizable compound (A) and / or the polymerization starts. The preparation temperature of the solution after the addition of the agent is preferably 30 ° C to 80 ° C.
The relief forming layer of the present application preferably has a thickness of 0.05 mm or more before and after crosslinking. From the viewpoint of satisfying various flexographic printing aptitudes such as abrasion resistance and ink transferability, 0.05 to 10 mm is preferable, 0.05 to 7 mm is more preferable, and 0.05 to 0.3 mm is particularly preferable. .

[Relief printing plate and its manufacture]
The resin printing plate precursor for laser engraving obtained as described above can produce a relief printing plate through the following steps in sequence.
The first example includes (1a) a step of irradiating a resin printing plate precursor for laser engraving with actinic rays to crosslink the relief forming layer, and (2) a step of laser engraving the crosslinked relief forming layer.
The second example includes (1b) a step of heating the resin printing plate precursor for laser engraving to crosslink the relief forming layer, and (2) a step of laser engraving the cross-linked relief forming layer.
The above (1a) and (1b) may be used in combination, and may be a simultaneous process or a separate process.
Furthermore, you may include the following process as needed. Following step (2), (3) rinsing the engraved surface with water or a liquid containing water as a main component, (4) drying the engraved relief forming layer, and (5) further crosslinking the relief forming layer Process.

Step (1a) or (1b) is a step of crosslinking the relief forming layer of the resin printing plate precursor for laser engraving. The relief forming layer of the present invention preferably contains a binder (B), a photothermal conversion agent (C), a polymerization initiator, and a polymerizable compound (A), and step (1a) or (1b) is a polymerization initiator. In this step, the polymerizable compound (A) is polymerized by action to form a crosslink. The polymerization initiator is a radical generator, and is broadly classified into a photopolymerization initiator and a thermal polymerization initiator depending on whether the trigger for generating radicals is light or heat.
When the relief forming layer contains a photopolymerization initiator, the relief forming layer can be crosslinked by irradiating the relief forming layer with an actinic ray that triggers the photopolymerization initiator. The irradiation with actinic light is generally performed on the entire surface of the relief forming layer. Visible light, ultraviolet light, or an electron beam is mentioned as actinic light, but ultraviolet light is the most common. If the support forming side of the relief forming layer is the back side, the surface may only be irradiated with actinic rays, but if the support is a transparent film that transmits actinic rays, it is preferable to irradiate actinic rays also from the back side. . When the protective film exists, the irradiation from the surface may be performed with the protective film provided or after the protective film is peeled off. Since polymerization inhibition may occur in the presence of oxygen, the crosslinkable relief forming layer may be covered with a vinyl chloride sheet and evacuated and then irradiated with actinic rays.

When the relief-forming layer contains a thermal polymerization initiator (the above-mentioned photopolymerization initiator can also be a thermal polymerization initiator), the relief-forming layer is crosslinked by heating the resin printing plate precursor for laser engraving. can do. Examples of the heating means include a method of heating the printing plate precursor in a hot air oven or a far infrared oven for a predetermined time, and a method of contacting the heated roll for a predetermined time.
In the step (1a) using light, although an apparatus for irradiating actinic rays is relatively expensive, the printing plate precursor does not become high temperature, so there are almost no restrictions on the raw materials of the printing plate precursor. The step (1b) using heat has an advantage that an extra expensive apparatus is not required, but since the printing plate precursor becomes high temperature, the thermoplastic polymer that becomes flexible at high temperature may be deformed during heating. The raw materials to be used must be carefully selected.
A thermal polymerization initiator can be added during the thermal crosslinking. In principle, commercial thermal polymerization initiators for free radical polymerization can be used as polymerization initiators, for example compounds containing suitable peroxides, hydroperoxides or azo groups. Typical vulcanizing agents are also used for crosslinking.
Thermal crosslinking can also be performed by adding a heat-curable resin, such as an epoxy resin, as a crosslinking component to the layer.

As a method for crosslinking the relief forming layer of the resin printing plate precursor for laser engraving, in the present application, crosslinking by heating is preferable from the viewpoint that the relief forming layer can be uniformly cured (crosslinked) from the surface to the inside. In the case of photocrosslinking, light is preferentially absorbed on the surface of the relief forming layer, which may cause a problem that sufficient light does not reach the deep part of the layer, and is cured (crosslinked) on the surface and inside of the relief forming layer. Is also uneven (in the case of thermal crosslinking, sufficient heat is uniformly applied from the surface to the inside of the relief forming layer).
By crosslinking the relief forming layer, there is an advantage that the relief formed first after laser engraving becomes sharp, and second, the adhesiveness of engraving residue generated during laser engraving is suppressed. When an uncrosslinked relief forming layer is laser-engraved, unintended portions are likely to melt and deform due to residual heat that has propagated around the laser-irradiated portion, and a sharp relief may not be obtained. In addition, as a general property of a material, a material having a low molecular weight tends to be liquid rather than solid, that is, the adhesiveness tends to be strong. The engraving residue generated when engraving the relief forming layer tends to become more tacky as more low-molecular materials are used. Since the polymerizable compound (A), which is a low molecule, becomes a polymer by crosslinking, the generated engraving residue tends to be less tacky.

  The Shore A hardness of the relief forming layer after crosslinking is preferably 50 ° to 90 °. By using a relief forming layer having a Shore A hardness of 50 ° or more, even if a fine halftone dot formed by engraving is subjected to a strong printing pressure of a relief printing press, it does not collapse and can be printed normally. By using a relief forming layer having a Shore A hardness of 90 ° or less, it is possible to prevent faint printing in a solid portion even in flexographic printing with a kiss touch.

(2) The step of laser engraving the crosslinked relief forming layer is a step of irradiating a laser beam corresponding to an image to be formed on the relief forming layer to form a relief, preferably to form A step of controlling the laser head with a computer based on digital image data and irradiating the relief forming layer with scanning is exemplified. When an infrared laser is irradiated, molecules in the relief forming layer undergo molecular vibrations and heat is generated. When a high-power laser such as a carbon dioxide laser or a YAG laser is used as an infrared laser, a large amount of heat is generated in the laser irradiation portion, and molecules in the photosensitive layer are selectively cut by molecular cutting or ionization, that is, Sculpture is made. The advantage of laser engraving is that the engraving depth can be set arbitrarily, so that the structure can be controlled three-dimensionally. For example, by engraving with a shallow or shoulder on the part where fine halftone dots are printed, it is possible to prevent the relief from falling down due to printing pressure, and deeply engrave the part of the groove where fine cut characters are printed. Therefore, it becomes difficult for the ink to be buried in the groove, and it is possible to suppress the crushing of the extracted characters.
In particular, when engraving with an infrared laser corresponding to the maximum absorption wavelength of the photothermal conversion agent (C), a more sensitive and sharp relief can be obtained.

When engraving residue is attached to the engraving surface, a step (3) of rinsing the engraving residue by rinsing the engraving surface with water or a liquid containing water as a main component may be added. As a means for rinsing, a method of spraying high-pressure water, a method of brushing the engraved surface mainly in the presence of water with a known batch-type or transport-type brush type washing machine as a photosensitive resin letterpress developing machine, etc. If the engraving residue cannot be removed, a rinsing solution to which soap is added may be used.
When the step (3) of rinsing the engraved surface is performed, it is preferable to add a step (4) of drying the engraved relief forming layer and volatilizing the rinse liquid.
Furthermore, you may add the process (5) which further bridge | crosslinks a relief forming layer as needed. By performing the additional crosslinking step (5), the relief formed by engraving can be further strengthened.
The relief printing plate produced by the method of the present invention can be printed with oil-based ink or UV ink by a letterpress printing machine, and can also be printed with UV ink by a flexographic printing machine.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
<Example 1>
In a three-necked flask equipped with a stirring blade and a cooling tube, 54 parts by mass of “GOHSENAL T-215 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., PVA derivative)” as a binder (B) and “Photothermal conversion agent (C)” D99-009 "(phthalocyanine compound, manufactured by Yamamoto Kasei), 20 parts by mass of diethylene glycol as a plasticizer, 35 parts by mass of water and 12 parts by mass of ethanol as a solvent, and heated at 70 ° C for 120 minutes with stirring. The polymer was dissolved. Furthermore, 25 parts by mass of Sartomer CD536 (manufactured by Sartomer) as an ethylenically unsaturated monomer as a polymerizable compound and 1.6 parts by mass of “Irgacure” 184 (α-hydroxyketone, manufactured by Ciba Geigy Co., Ltd.) as a polymerization initiator are added. Then, the mixture was stirred for 30 minutes to obtain a solution of a crosslinkable resin composition for laser engraving for a flowable crosslinkable relief forming layer.

  A spacer (frame) with a predetermined thickness is placed on the PET substrate, and the solution of the resin composition for laser engraving is gently cast so as not to flow out of the spacer (frame), and dried in an oven at 70 ° C. for 3 hours. A relief forming layer having a thickness of about 1 mm was provided to prepare a resin printing plate precursor for laser engraving.

Next, the obtained relief forming layer of the original plate was heated at 100 ° C. for 2.5 hours to thermally crosslink the relief forming layer.
For the relief forming layer, “CO2 laser marker ML-Z9500” (manufactured by Keyence Corporation) equipped with a carbon dioxide laser with a maximum output of 30 W was used as a carbon dioxide laser engraving machine. Engraving conditions were set such that the laser output was 15 W, the scanning speed was 100 mm / second, and the pitch interval was 0.15 mm, and a 2 cm square solid part was engraved to produce a relief printing plate.

  On the other hand, as a near-infrared laser engraving machine, “FD-100” (manufactured by Tosei Electrobeam Co., Ltd.) equipped with a semiconductor laser having a maximum output of 16 W (laser oscillation wavelength: 840 nm) was used. Engraving conditions were set such that the laser output was 15 W, the scanning speed was 100 mm / second, and the pitch interval was 0.15 mm, and a 2 cm square solid part was engraved to produce a relief printing plate.

  The sculpture depth is measured by observing the cross section of the solid sculpture part with an ultra-deep color 3D shape measurement microscope VK9510 (manufactured by Keyence Corporation) and reading the difference in height between the relief forming layer surface and the sculptured part. The results are shown in Table 12 (the following evaluation is also shown in Table 12).

<Examples 2 to 10>
In Example 1, the same procedure was performed except that the exemplified compound M-2 to M-10 were used in the same amount instead of Sartomer CD536 (M-1 of the exemplified compound) as the polymerizable compound.

<Example 11>
In Example 1 above, the same procedure was performed except that 10 parts by mass of 25 parts by mass of the polymerizable compound (A) were replaced with the following compounds.

<Example 12>
In Example 1, the same procedure was performed except that the photothermal conversion agent was changed to carbon black (manufactured by Mitsubishi Chemical, Diablack SA).
<Examples 13-24> In Examples 1-12, the laser for engraving was changed from a semiconductor laser to a CO2 laser, and Examples 13-24 were obtained.

<Comparative Example 1>
The same procedure as in Example 1 was performed except that the polymerizable compound was replaced with DPHA (dipentaerythritol hexaacrylate) (manufactured by Toagosei Co., Ltd.).
<Comparative example 2>
The engraving laser of Comparative Example 1 was changed from a semiconductor laser to a CO2 laser.
The evaluation results of engraving sensitivity are shown below.

Claims (12)

A resin composition for laser engraving, comprising at least a polymerizable monomer (A) having one or more acetal sites and a hydrophilic polymer containing a hydroxyethylene unit as a binder polymer (B).   The resin composition for laser engraving according to claim 1, comprising a photothermal conversion agent (C) capable of absorbing light having a wavelength of 700 to 1300 nm.   The resin composition for laser engraving according to claim 2, wherein the photothermal conversion agent (C) is carbon black.   The resin composition for laser engraving according to claim 2, wherein the photothermal conversion agent (C) is a cyanine compound and / or a phthalocyanine compound.   The resin composition for laser engraving according to claim 1, further comprising a sulfur atom-containing polymerizable compound.   The resin composition for laser engraving according to claim 5, wherein the hydrophilic polymer is a polyvinyl alcohol (PVA) derivative.   A resin printing plate precursor for laser engraving, comprising a relief forming layer comprising the resin composition for laser engraving according to claim 1.   A method for producing a relief printing plate, comprising: a step 1) of crosslinking the relief-forming layer according to claim 7 with light and / or heat; and a step 2) of laser engraving the crosslinked relief-forming layer.   9. The method for producing a relief printing plate according to claim 8, wherein the step 1) is a step of crosslinking the relief forming layer with heat.   A relief printing plate produced by the method according to claim 8 or 9.   The relief printing plate according to claim 10, wherein the relief-forming layer crosslinked by the method according to claim 8 or 9 has a thickness of 0.05 mm or more.   The relief printing plate according to claim 10 or 11, wherein the Shore A hardness of the relief-forming layer crosslinked by the method according to claim 8 or 9 is 50 to 90 °.