JP5206434B2 - Photosensitive resin composition for letterpress production - Google Patents

Description

The present invention relates to a photosensitive resin composition suitable for producing a resin letterpress used for letterpress printing, and more specifically, has an appropriate rubber hardness necessary for letterpress printing, an aromatic solvent, The present invention relates to a photosensitive resin composition for letterpress production having excellent resistance to any of alcohol-based solvents and water-based inks.

Conventionally, a photolithography method, a vacuum deposition method, or the like has been generally used for forming a fine pattern of a display panel or an electronic circuit. The printing method is expected to reduce costs, such as faster processing speed, less waste associated with the process, and higher utilization efficiency of materials compared to the photolithography method, vacuum deposition method and the like.

As the printing method, inkjet printing method, flexographic printing method, offset printing method, gravure printing method, screen printing method, etc. are known, and among them, relief printing using particularly elastic rubber plates and resin plates is used. Since the printing speed is fast and the resin relief plate is used, the ink is transferred to the surface of the convex part, and the convex part comes into contact with the surface of the printing material, so that the printing part is not stained. In particular, a method for producing a member such as a display panel or an electronic circuit by using a relief printing method has attracted attention.

In the ink used to form display panels and electronic circuits, as solvents for dissolving or dispersing functional compounds, aromatic solvents such as toluene, xylene and anisole, alcohol solvents such as isopropyl alcohol and ethanol, And water. Moreover, in order to form a fine pattern using such an ink, it is necessary to have resistance to these various solvents so that swelling and deformation do not occur.

As the photosensitive resin composition for letterpress production, those mainly composed of rubber components such as polybutadiene, SBR and polyisoprene, those mainly composed of water-soluble polymers such as water-soluble polyamide, polyvinyl alcohol and cellulose derivatives, or Those mainly composed of polyester and polyether urethane acrylate are used.

However, photosensitive resins mainly composed of rubber components such as polybutadiene, SBR, and polyisoprene have excellent resistance to highly polar solvents and water, and are therefore applicable to printing water-based and alcohol-based inks. It cannot be applied to inks that use ether or aromatic solvents because of their poor resistance.

A photosensitive resin mainly composed of a water-soluble polymer such as water-soluble polyamide, polyvinyl alcohol, or cellulose derivative has a solubility parameter (hereinafter sometimes abbreviated as SP value) of the resin mainly composed of 13.6 (hereinafter, abbreviated as SP value). Nylon), 12.6 (polyvinyl alcohol), and 15.7 (cellulose), which are sufficiently separated from the SP value 8.9 of toluene, which is a representative aromatic solvent, and the SP value 8.8 of xylene, Although it has resistance to an aromatic solvent, there are problems that the resulting printing plate has a very high hardness and that damage to the substrate during printing is large, and that the resistance to water-based ink is poor.

Liquid photosensitive resin compositions mainly composed of polyester and polyether-based urethane acrylate are widely used for letterpress production because of their excellent friction resistance, but they are poor in resistance to aromatic solvents and can be used for repeated printing processes. As a result, the printing plate swells and the printing accuracy is remarkably deteriorated. In an extreme case, the relief printing plate may be damaged.

Photosensitive resin composition comprising a specific unsaturated polyester using a low molecular weight alkyl diol and a high molecular weight polyalkylene glycol as a diol component as a photosensitive resin for a printing plate having resistance to an ink using an aromatic solvent Is known (see, for example, Patent Document 1). However, this unsaturated polyester-based photosensitive resin composition is excellent in image forming properties, but the polymerization is slow and non-uniform because the copolymerization property of unsaturated polyester and ethylenically unsaturated monomer is not good. Proceed to. Therefore, in order to obtain sufficient resistance and strength against the aromatic solvent, it is necessary to increase the exposure amount, resulting in a problem that the manufacturing time is increased and the resolution of image formation is impaired.

Photosensitive resin composition using both unsaturated polyester and polyester urethane prepolymer, and unsaturated polyester urethane resin with a highly reactive acrylate group introduced through a urethane bond at part of the polymer end of unsaturated polyester resin Proposed photosensitive resin compositions have been proposed (see, for example, Patent Documents 2 and 3). However, in these methods, although the polymerization rate and copolymerization properties of the unsaturated polyester resin and the monomer are improved, the resistance to the aromatic solvent in the case of forming a letterpress is insufficient.

Further, a flexographic printing plate using a fluorinated elastomer having a fluorinated polyether structure resistant to an aromatic hydrocarbon solvent has been proposed (for example, see Patent Document 4). However, a fluorine-based material is very expensive, and a resin relief printing pattern is formed by casting, so that it is unsuitable for reproducing a fine pattern. As described above, in the prior art, there is no one that has resistance to printing of any ink using an aromatic solvent, an alcohol solvent, water, etc., and there is a resin relief printing that solves all of these problems. The current situation is that it has not been obtained.

Japanese Patent Publication No.51-37320 JP-A-55-717 JP-A-6-43639 JP 2004-322329 A

In view of the above circumstances, the present invention has a suitable rubber hardness necessary for letterpress printing, and has a high resistance to any of inks using aromatic solvents, alcohol solvents, water, etc. It is a technical problem to provide a photosensitive resin composition for production.

  As a result of intensive studies to solve the above problems, the present inventors have produced a relief printing plate containing a specific prepolymer (A), an ethylenically unsaturated monomer (B), and a photopolymerization initiator (C) as components. Photosensitive resin composition (D) has an appropriate rubber hardness necessary for letterpress printing, and has excellent resistance to any of inks using aromatic solvents, alcohol solvents, water, etc. In particular, the present invention has been found to have excellent resistance to inks using aromatic solvents that are difficult to achieve with the prior art, and the present invention has been completed.

That is, the present invention
<1> In the photosensitive resin composition for letterpress production (D) containing the prepolymer (A), the ethylenically unsaturated monomer (B), and the photopolymerization initiator (C), the following [1] to [6] ] Is a photosensitive resin composition for producing letterpress.
[1] The prepolymer (A) is an unsaturated polyester polyol (a1) obtained by polycondensation of a polyhydric alcohol and a polycarboxylic acid, a polyisocyanate (a2), a functional group having active hydrogen, and ethylene. It is an unsaturated polyurethane prepolymer obtained by reacting at least the compound (a3) having both of unsaturated unsaturated bonds in the molecule.
[2] The unsaturated polyester polyol (a1) is an unsaturated polyester polyol having at least polyethylene glycol as a polyhydric alcohol component and at least an aliphatic unsaturated dicarboxylic acid as an essential component as a polyvalent carboxylic acid component.
[3] The ethylenically unsaturated monomer (B) contains at least a monomer (b1) represented by the following general formula (1).
(In the formula, R ¹ is H or CH ₃ , R ² is an alkylene group having 2 to 5 carbon atoms, n is 1 to 4, R ³ is an alkylene group having 2 to 8 carbon atoms, the following general formula (2), General formula (3) is shown.)
[4] The weight ratio of the prepolymer (A) to the ethylenically unsaturated monomer (B) is in the range of 30 to 70/70 to 30.
[5] The acid value of the photosensitive resin composition (D) for producing a relief printing plate is in the range of 50 to 150 mgKOH / g.
[6] A cured product obtained by photopolymerizing the photosensitive resin composition (D) for producing a relief plate,
(1) Shore A 60-90 ° in JIS rubber hardness, and
(2) The weight increase rate when immersed in anisole, isopropyl alcohol and water at 25 ° C. for 24 hours is 15% by weight or less.

Moreover, as a preferable aspect,
<2> The unsaturated polyester polyol (a1) is used in an amount of 40 to 70% by weight of polyethylene glycol based on the total weight of the polyhydric alcohol component and polyvalent carboxylic acid component used in the condensation polymerization, and The photosensitive resin composition for letterpress production according to <1>, wherein the ethylenically unsaturated bond concentration is in the range of 0.5 to 3.0 mmol / g.

According to the present invention, a relief printing plate having an appropriate rubber hardness required for relief printing and having resistance to any of inks using aromatic solvents, alcohol solvents, water, etc. is produced. Therefore, a suitable photosensitive resin composition for producing a relief printing plate can be provided.

The configuration of the present invention will be described in more detail as follows.
(A) Prepolymer The prepolymer (A), which is a constituent of the present invention, comprises at least two unsaturated polyester polyols (a1) obtained by polycondensation of polyethylene glycol and an aliphatic unsaturated dicarboxylic acid and two isocyanate groups. An unsaturated polyurethane prepolymer obtained by reacting the above-described polyisocyanate (a2), a functional group having active hydrogen and a compound (a3) having both ethylenically unsaturated bonds in the molecule, and a polymer main chain portion It is essential to have a flexible oxyethylene structure and to have an ethylenically unsaturated group in both the polymer main chain portion and the polymer terminal portion. Since the unsaturated polyester polyol (a1) containing polyethylene glycol having high hydrophilicity is used for the prepolymer (A), a relief printing plate having resistance to aromatic solvents, alcohol solvents, water and the like It becomes possible to provide a photosensitive resin for production. Moreover, since the unsaturated polyurethane prepolymer obtained has good copolymerizability with the ethylenically unsaturated monomer (B), it becomes possible to obtain a cured product having a dense cross-linked structure even with a smaller exposure amount, It is possible to provide a photosensitive resin for producing a relief plate having excellent resistance to any of an aromatic solvent, an alcohol solvent, water, and the like.

(A1) Unsaturated polyester polyol Unsaturated polyester polyol (a1) used for unsaturated polyurethane prepolymer is obtained by polycondensation of a dihydric or higher polyhydric alcohol component and a divalent or higher polyvalent carboxylic acid component. However, in order to improve resistance to aromatic solvents, a polyhydric alcohol component consisting of polyethylene glycol alone or a mixture of a polyhydric alcohol other than polyethylene glycol and polyethylene glycol and an aliphatic unsaturated dicarboxylic acid alone or an aliphatic unsaturated dicarboxylic acid. It must be obtained by polycondensation of a polyvalent carboxylic acid component comprising a mixture of a polyvalent carboxylic acid other than an acid and an aliphatic unsaturated dicarboxylic acid.

Examples of polyethylene glycol include diethylene glycol, triethylene glycol, and polyethylene glycol (molecular weight 200 to 20000). In particular, diethylene glycol, triethylene glycol, and polyethylene glycol having a molecular weight of 200 to 600 are easy to produce a polyester resin. In addition, it is preferable because it can impart an appropriate rubber hardness necessary for the relief printing and resistance to an aromatic solvent.

As polyhydric alcohol components other than polyethylene glycol, for example, as divalent alcohol components, propylene glycol, dipropylene glycol, polyoxypropylene glycol, butanediol, polyoxytetramethylene glycol, pentanediol, 3-methyl-1,5 -A pentanediol, hexanediol, etc. are mentioned, As a trihydric or more alcohol component, a glycerol, a trimethylol propane, a pentaerythritol, etc. are mentioned. Among these, as the polyhydric alcohol component, butanediol, 3-methyl-1,5-pentanediol, and hexanediol are preferable because they can impart resistance to alcohol solvents and water.

Examples of the aliphatic unsaturated dicarboxylic acid component include maleic acid, fumaric acid, itaconic acid, mesaconic acid, and citraconic acid, and anhydrides thereof include maleic anhydride, itaconic anhydride, citraconic anhydride, In particular, fumaric acid, maleic acid, and maleic anhydride are preferable because they are inexpensive and easy to produce polyester resins.

Examples of the polyvalent carboxylic acid component other than the aliphatic unsaturated dicarboxylic acid include divalent carboxylic acid components, aromatic dibasic acids such as phthalic acid, isophthalic acid, and terephthalic acid, or anhydrides thereof; tetrahydrophthalic acid, And alicyclic dibasic acids such as hexahydrophthalic acid or anhydrides thereof; aliphatic dibasic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, and azelaic acid or anhydrides thereof; carbon number Examples thereof include succinic acid substituted with an alkyl group or alkenyl group of 6 to 18 or an anhydride thereof, and examples of the trivalent or higher carboxylic acid component include trimellitic acid, pyromellitic acid or an anhydride thereof. As the polyvalent carboxylic acid component other than the aliphatic unsaturated dicarboxylic acid, succinic acid, glutaric acid, adipic acid, and sebacic acid are inexpensive and preferable because both the resistance to an aromatic solvent and the resistance to water can be achieved. .

The polyethylene glycol in the present invention preferably contains 40 to 70% by weight based on the total weight of the polyhydric alcohol component and polyhydric carboxylic acid component used in the production of the unsaturated polyester polyol (a1). If it is less than 40% by weight, the hydrophilicity becomes weak and the resistance to aromatic solvents, ketone solvents and ester solvents tends to deteriorate. On the other hand, if it exceeds 70% by weight, the hydrophilicity is too strong, and the resistance to alcohol and water tends to decrease.

The aliphatic unsaturated dicarboxylic acid in the present invention varies depending on the molecular weight of the polyester polyol and the content of polyethylene glycol, but is adjusted so that the ethylenically unsaturated bond concentration is in the range of 0.5 to 3.0 mmol / g. It is preferable. The ethylenically unsaturated bond concentration represents the number of ethylenically unsaturated bonds in the polyester polyol, and is defined by the following formula.
“Ethylenic unsaturated bond concentration (mmol / g)” = (X × Y) / Z × 1000
X: Number of ethylenically unsaturated groups in aliphatic unsaturated dicarboxylic acid Y: Number of moles of aliphatic unsaturated dicarboxylic acid Z: Total weight (g) of alcohol component and acid component of polyester polyol raw material

That is, when the ethylenically unsaturated bond concentration is less than 0.5 mmol / g, the crosslinking density of the cured product is lowered, and the resistance to aromatic solvents and alcohol solvents tends to deteriorate, and 3.0 mmol / g is reduced. If it exceeds, the crosslink density of the cured product becomes too high, and not only the rubber hardness becomes high, but also it becomes brittle and the relief tends to be lost.

The production of the unsaturated polyester polyol (a1) is such that the total number of moles of hydroxyl groups contained in the polyhydric alcohol component is in excess of 10 to 100 mol% with respect to the total number of moles of carboxyl groups contained in the polyvalent carboxylic acid component. It is appropriate to carry out dehydration condensation at a temperature of 150 to 240 ° C. in a stream of inert gas by a known method at a raw material composition ratio.

In this invention, it is preferable that the molecular weight of unsaturated polyester polyol (a1) is 500-5000 in a number average molecular weight. When the number average molecular weight is less than 500, when the unsaturated urethane prepolymer (A) is used, the urethane bond concentration is increased, and the viscosity stability of the photosensitive resin composition may be deteriorated. Hardness tends to increase. When the number average molecular weight exceeds 5000, the resin viscosity increases, and the developability may be further deteriorated.

The polyisocyanate (a2) may be a compound having two or more isocyanate groups such as diisocyanate and triisocyanate. Examples of the diisocyanate include 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, p-xylylene. Diisocyanate, m-xylylene diisocyanate, p-hydrogenated xylylene diisocyanate, m-hydrogenated xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate , Naphthalene diisocyanate, p-phenylene diisocyanate and the like. Examples of the triisocyanate include a biuret form of tolylene diisocyanate and its isocyanurate form, a biuret form of isophorone diisocyanate, and its isocyanurate form, a biuret form of 1,6-hexamethylene diisocyanate, and its isocyanurate form. Etc. Among them, diisocyanate is preferable because it is easy to produce an unsaturated polyurethane prepolymer. Furthermore, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, and 1,6-hexamethylene diisocyanate are preferable.

The compound (a3) having both a functional group having active hydrogen and an ethylenically unsaturated bond in the molecule may be any compound having both a functional group having active hydrogen and an ethylenically unsaturated bond in the molecule. Is a compound having a hydroxy group and an ethylenically unsaturated bond in the molecule, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) Examples include acrylate, polypropylene glycol mono (meth) acrylate, glycerin mono or di (meth) acrylate. Of these, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and polyethylene glycol mono (meth) acrylate are preferred from the viewpoint of resistance to aromatic solvents.

The unsaturated polyurethane prepolymer (A) can be obtained by various methods. For example, by reacting unsaturated polyester polyol (a1) and polyisocyanate (a2) at a reaction temperature of 20 to 80 ° C., a prepolymer precursor having an isocyanate group at the polymer terminal is synthesized, and active hydrogen is added to this. It can be obtained by adding a compound (a3) having both a functional group and an ethylenically unsaturated bond in the molecule. The reaction can be completed by continuing the incubation until there is no trace of the NCO characteristic absorption band near 2230 cm ⁻¹ by IR measurement.

  At this time, the ratio of the unsaturated polyester polyol (a1), the polyisocyanate (a2), the functional group having active hydrogen and the compound (a3) having both ethylenically unsaturated bonds in the molecule is not particularly limited. The molar ratio (NCO group / OH group) of the isocyanate group (NCO group) of the polyisocyanate (a2) to the hydroxyl group (OH group) of the unsaturated polyester polyol (a1) is 1.1 to 2.0. Thus, a prepolymer precursor having an NCO group at the polymer terminal is synthesized, and a hydroxyl group (OH group) of the compound (a3) having both a functional group having active hydrogen and an ethylenically unsaturated bond in the molecule is added to this. It is preferable to react so that it may become equivalent to the polymer chain terminal NCO group of a prepolymer precursor. When the ratio of the unsaturated polyester polyol (a1), the polyisocyanate (a2), the functional group having active hydrogen and the compound (a3) having both ethylenically unsaturated bonds in the molecule is out of the above range, unreacted Various physical properties may be reduced due to residual saturated polyester polyol, and storage stability may be decreased due to residual residual isocyanate groups.

  A catalyst may be used in the reaction of the unsaturated polyester polyol (a1), the polyisocyanate (a2), the functional group having active hydrogen, and the compound (a3) having both ethylenically unsaturated bonds in the molecule. Examples of such a catalyst include di-n-butyltin dilaurate, stannous octoate, triethylenediamine, diethylenediamine, triethylamine, naphthenic acid metal salt, octylic acid metal salt such as lead octylate, and the like. These catalysts may be used alone or in combination of two or more.

The number average molecular weight of the unsaturated polyurethane prepolymer (A) of the present invention is preferably 1000 to 10,000. When the number average molecular weight is less than 1000, the mechanical strength of the photocured product is low and durability against repeated printing may be deteriorated. When the number average molecular weight exceeds 10,000, developability may be deteriorated.

(B) Ethylenically Unsaturated Monomer As the ethylenically unsaturated monomer (B) in the present invention, a carboxyl group is included in the molecule represented by the general formula (1) in order to optimize the resistance to the aromatic solvent and the rubber hardness. It is necessary to contain the monomer (b1) having a group as an essential component.
(In the formula, R ¹ is H or CH ₃ , R ² is an alkylene group having 2 to 5 carbon atoms, n is 1 to 4, R ³ is an alkylene group having 2 to 8 carbon atoms, the following general formula (2), General formula (3) is shown.)

The monomer (b1) having a carboxyl group in the molecule represented by the general formula (1) is an equimolar amount of hydroxyalkyl (meth) acrylate or polyalkylene glycol mono (meth) acrylate and polycarboxylic acid or anhydride thereof. For example, commercially available products include 2-methacryloyloxyethyl succinic acid (trade name HO-MS, manufactured by Kyoeisha Chemical Co., Ltd.), 2-acryloyloxyethyl succinic acid ( Shin-Nakamura Chemical Co., Ltd., trade name NK Ester A-SA), 2-methacryloyloxyethylphthalic acid (Mitsubishi Rayon Co., Ltd., trade name acrylate PA), 2-acryloyloxyethyl phthalic acid (Kyoeisha Chemical Co., Ltd.) Product name HOA-MPL), 2-methacryloyloxyethyl hex Hydrophthalic acid (manufactured by Mitsubishi Rayon Co., Ltd., trade name ACRYESTER HH), 2-acryloyloxyethyl hexahydrophthalic acid (manufactured by Kyoeisha Chemical Co., HOA-HH), and the like. Among them, 2- (meth) acryloyloxyethyl succinic acid is particularly preferable from the viewpoint of flexibility of the photocured product.

The ethylenically unsaturated monomer (b1) having a carboxyl group in the present invention varies depending on the amount of polyethylene glycol used in the unsaturated polyester polyol (a1) or the ethylenically unsaturated bond concentration, but the photosensitive resin composition (D ) Is preferably 20 to 60% by weight. When it is less than 20% by weight, the resistance to the aromatic solvent tends to deteriorate, and when it exceeds 60% by weight, the resistance to water tends to deteriorate.

Other ethylenically unsaturated monomers can be used as part of the monomer (b1) having a carboxyl group in the molecule represented by the general formula (1). Examples of the monomer other than the ethylenically unsaturated monomer (b1) represented by the general formula (1) include (meth) acrylic acid and derivatives thereof such as alkyl (meth) acrylate, cycloalkyl (meth) acrylate, and halogenated alkyl ( (Meth) acrylate, alkoxyalkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, aminoalkyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, allyl (meth) acrylate, glycidyl (meth) acrylate, benzyl (meth) acrylate , Phenoxy (meth) acrylate, mono- or di (meth) acrylate of alkylene glycol and polyoxyalkylene glycol, polyalkylene oxide-modified bisphenol A di (meth) acrylate Trimethylolpropane mono, di, tri (meth) acrylate, pentaerythritol mono, di, tri, tetra (meth) acrylate, (meth) acrylamide or derivatives thereof, such as alkyl or hydroxyalkyl groups, N-substituted or N, N'-substituted (meth) acrylamide, diacetone (meth) acrylamide, N, N'-alkylenebis (meth) acrylamide and the like can be mentioned. Among them, hydroxyalkyl (meth) acrylate, methoxypolyoxyalkylene glycol (meth) acrylate, polyoxyalkylene glycol mono- or di (meth) acrylate, polyalkylene oxide-modified bisphenol A di (meth) acrylate are particularly aromatic. It is preferable because both resistance to the group solvent and resistance to water can be achieved, and the amount used is preferably 1 to 30% by weight with respect to the photosensitive resin composition (D).

In addition, as the ethylenically unsaturated monomer (B) in the present invention, the ethylenically unsaturated monomer (b1) having a carboxyl group in the molecule represented by the general formula (1) is essential. As a saturated monomer (B), by using an ethylenically unsaturated monomer (b1) having a carboxyl group in the molecule represented by the general formula (1) as an essential component of a photosensitive resin for letterpress production, the cured product can be obtained. This is because the relief printing plate has an appropriate rubber hardness and can have resistance to an aromatic solvent and water.

(C) Photopolymerization initiator The photopolymerization initiator (C) in the present invention is not particularly limited as long as it is a polymerization initiator by light. Examples of acetophenones include diethoxyacetophenone and 2-hydroxy-2. -Methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) -phenyl- (2-hydroxy- 2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, and benzoins include benzoin, benzoin methyl ether, benzoin ethyl ether, Benzoin isopropyl ether, benzoin isobutyl ether, benzyl dimethyl Examples of tilketals and benzophenones include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, and xanthones such as xanthone, thioxanthone, and anthraquinones such as anthraquinone, 2-methylanthraquinone, and 2-ethylanthraquinone. Two or more of these photopolymerization initiators may be used.

The addition amount of the photopolymerization initiator (C) is usually preferably in the range of 0.1 to 10% by weight with respect to the total amount of the prepolymer (A) and the ethylenically unsaturated monomer (B). If it is less than 0.1% by weight, it is difficult to photopolymerize at a predetermined exposure amount, the plate-making time is remarkably increased, and the crosslink density is lowered due to deterioration of copolymerizability. Therefore, an aromatic solvent, There is a risk of deterioration of resistance to alcohol solvents. On the other hand, if it exceeds 10% by weight, the pot life may be shortened and gelation may occur during storage, and the sensitivity may be too high during plate making, making it difficult to control the exposure time. From the viewpoint of image reproducibility during continuous plate-making, the content is more preferably 0.5 to 5% by weight.

The photosensitive resin composition for letterpress production (D) in the present invention is uniform by heating the prepolymer (A), the ethylenically unsaturated monomer (B), and the photopolymerization initiator (C) at room temperature or by heating. It can obtain by mixing. In that case, the weight ratio of the prepolymer (A) to the ethylenically unsaturated monomer (B) is 30 to 70/70 in order to optimize rubber hardness and improve resistance to aromatic solvents, alcohol solvents and water. The acid value of the photosensitive resin composition (D) must be 50 to 150 mgKOH / g.

The weight ratio of the prepolymer (A) to the ethylenically unsaturated monomer (B) is prepolymer (A) / ethylenically unsaturated monomer (B) = 30 to 70/70 to 30, and has a dense cross-linked structure. It is possible to provide a photosensitive resin for producing letterpress that can be made into a product. When the prepolymer (A) / ethylenically unsaturated monomer (B) is less than 30/70, the resolution of image formation is deteriorated, or curing shrinkage occurs during photopolymerization, and the plate curls during plate making. Or the convex portion does not have a uniform and constant thickness. When the prepolymer (A) / ethylenically unsaturated monomer (B) exceeds 70/30, the copolymerization with the ethylenically unsaturated monomer (B) is deteriorated, so the polymerization rate is lowered, and the aromatic solvent, When the resistance to the alcoholic solvent is deteriorated, the strength of the cured product is reduced, and a relief printing plate is used, there is a problem that the plate is chipped during repeated printing.

When the acid value of the photosensitive resin composition (D) is 50 to 150 mgKOH / g, it becomes possible to obtain a highly polar cured product, high strength, and excellent for both aromatic solvents and water. It is possible to provide a photosensitive resin for producing a relief plate having resistance. When the acid value is less than 50 mgKOH / g, the number of polar groups in the cured product is insufficient, and it becomes impossible to maintain the resistance to the aromatic solvent. On the other hand, when the acid value exceeds 150 mgKOH / g, the polarity of the cured product becomes too strong, the resistance to water is deteriorated, and the hygroscopic property is high, which causes a problem of reducing the strength of the cured product.

Moreover, the cured product when the photosensitive resin composition (D) is photopolymerized can reduce the load on the substrate during printing when the rubber hardness is Shore A 60 to 90 ° in JIS rubber hardness. In thin film printing, printing with a uniform film thickness can be performed with high accuracy. When the rubber hardness is less than Shore A 60 °, relief deformation occurs even with a slight printing pressure, and the printed line becomes thick and a delicate image cannot be obtained. When the rubber hardness exceeds 90 ° Shore A, it is difficult to wind the plate around the plate cylinder due to the plate being hard, or the ink is poorly adhered, making it difficult to print with a uniform film thickness.

Furthermore, when the photosensitive resin composition (D) is photocured, the weight increase rate of the cured product when immersed in anisole, isopropyl alcohol and water at 25 ° C. for 24 hours is 15% or less. Even with repeated printing using printing inks composed of various solvents such as aromatic solvents, alcohol solvents, and water, it is possible to obtain highly accurate printed matter with little decrease in the dimensional accuracy of the resin relief printing plate. It becomes. The weight increase rate is preferably as low as possible, and is more preferably 10% or less in consideration of the number of times of normal repeated printing. More preferably, it is 7% or less.

In general, anisole has an ether bond in the molecule as compared with an aromatic solvent such as toluene and xylene, and therefore has high solubility in a plate material. Therefore, if resistance to anisole can be maintained, it can be said that it has resistance to various aromatic solvents. Furthermore, if resistance to isopropyl alcohol and water having a high polarity can be maintained, it can be said that they are resistant to various aromatic solvents, alcohol solvents, and water.

The viscosity of the photosensitive resin composition (D) of the present invention is preferably in the range of 2000 to 25000 mPa · s at 25 ° C. If it is lower than 2000 mPa · s, the liquid resin overflows to a place other than the effective image area at the time of producing the original plate, resulting in poor workability and lowering of the plate thickness accuracy of the original plate. When it exceeds 25000 mPa · s, pretreatment such as heating may be necessary before use.

The photosensitive resin composition for letterpress production (D) thus obtained has an appropriate rubber hardness necessary for letterpress printing, and is an ink that uses an aromatic solvent, an alcohol solvent, water, and the like. It can be suitably used as a photosensitive resin composition for letterpress production having excellent resistance.

In the photosensitive resin composition (D) of the present invention, if necessary, a thermal polymerization inhibitor, other urethane acrylic oligomer, polyurethane resin, polyester resin, polyamide resin, polyimide resin, polyvinyl acetate, epoxy resin, etc. Can be mixed and used. In addition, reinforcing fillers such as glass fibers and glass beads, and further additives such as stabilizers, plasticizers, mold release agents, and lubricants can be added to impart desired properties.

Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, 2,6-di-tert-butyl-p-cresol, pyrogallol, β-naphthol and the like. The addition amount of the thermal polymerization inhibitor is preferably in the range of 0.01 to 10% by weight with respect to the total amount of the prepolymer and the ethylenically unsaturated monomer.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples.

<Production Example 1> [Production of unsaturated polyurethane prepolymer (A-1)]
(Synthesis of unsaturated polyester polyol)
Polyethylene glycol (manufactured by NOF Corporation, average molecular weight 200, hereinafter abbreviated as PEG200) 5.74 mol, adipic acid (molecular weight 146, hereinafter abbreviated as AA) 3.83 mol, aliphatic Saturated dicarboxylic acid as fumaric acid (molecular weight 116, hereinafter abbreviated as FA) 0.43 mol, p-methoxyphenol (hereinafter abbreviated as MEHQ) 0.01 mol, and catalyst as tetra- A reaction vessel was charged with 0.005 mol of n-butyl titanate (hereinafter sometimes abbreviated as TBT), reacted in a nitrogen atmosphere at normal pressure at 200 ° C. for 4 hours, and further acidified at 200 ° C. under reduced pressure of 20 mmHg. By performing a dehydration condensation reaction until the value becomes 1 mgKOH / g or less, a hydroxyl value of 95 mgKOH / g, a polyethylene glycol content of 65 folds %, And give ethylenically unsaturated bond concentration 0.24 mmol / g, a hydroxyl value of unsaturated polyester polyol (PES-1).

(Synthesis of unsaturated polyurethane prepolymer)
66.0 parts by weight of unsaturated polyester polyol (PES-1) and 0.10 parts by weight of 2,6-di-tert-butyl-p-cresol (hereinafter sometimes abbreviated as BHT) as a thermal polymerization inhibitor Was added to a reaction vessel, and 19.5 parts by weight of 2,4-tolylene diisocyanate (hereinafter sometimes abbreviated as TDI) as a polyisocyanate was added thereto, and the mixture was stirred at 60 ° C. in a nitrogen atmosphere with good stirring. It was made to react for a time and the prepolymer precursor was obtained. Further, to this reaction product, 14.5 parts by weight of 2-hydroxyethyl methacrylate (hereinafter sometimes abbreviated as HEMA) as a compound having both a functional group having active hydrogen and an ethylenically unsaturated bond in the molecule, and 0.04 part by weight of dibutyltin dilaurate (hereinafter sometimes abbreviated as DBSL) was added as a catalyst, reacted at 80 ° C. for 3 hours, and the absorption peak of 2230 cm ⁻¹ isocyanate group disappeared by IR measurement. confirmed. Thereafter, the reaction vessel was cooled to obtain an unsaturated polyurethane prepolymer (A-1) shown in Table 1.

<Production Examples 2 to 7> [Production of unsaturated polyurethane prepolymers (A-2) to (A-7)]
With the composition shown in Table 1, polyester polyols (PES-1) to (PES-7) and unsaturated polyurethane prepolymers (A-2) to (A-7) are obtained by performing the same operations as in Production Example 1. Obtained.

Explanation of abbreviations in Table 1 DEG is diethylene glycol (molecular weight 106), PEG 200 is polyethylene glycol (manufactured by NOF Corporation, average molecular weight 200), PEG 400 is polyethylene glycol (manufactured by NOF Corporation, average molecular weight 400), and BG is 1. , 3-butanediol (molecular weight 90), MPD is 3-methyl-1,5-pentanediol (molecular weight 118), FA is fumaric acid (molecular weight 116), MA is maleic acid (molecular weight 116), AA is adipic acid ( Molecular weight 146), TDI is 2,4-tolylene diisocyanate, HDI is 1,6-hexamethylene diisocyanate, HEMA is 2-hydroxyethyl methacrylate, PEGM is polyethylene glycol (average molecular weight 350) monomethacrylate (manufactured by NOF Corporation, Product name BLEMMER PE-3 0, show that it is a hydroxyl value 128mgKOH / g).

<Example 1>
60.0 parts by weight of the unsaturated polyurethane prepolymer (A-1) produced in Production Example 1, and 2-acryloyloxyethyl succinic acid (manufactured by Shin-Nakamura Chemical Co., Ltd.) as the ethylenically unsaturated monomer represented by the general formula (1) , Trade name NK ester A-SA, acid value 257 mg KOH / g, hereinafter abbreviated as ASA) 30.0 parts by weight, ethylene oxide as a monomer component other than the ethylenically unsaturated monomer represented by the general formula (1) Modified (4 mol addition) bisphenol A diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name Light Acrylate BP-4EA, hereinafter abbreviated as BPDA) 10.0 parts by weight, 1-hydroxycyclohexylphenyl as photopolymerization initiator 2.0 parts by weight of a ketone (hereinafter sometimes abbreviated as HCHP), and BHT0. Charged parts by weight of the container, respectively, was obtained by 1 hour stirring at about 60 ° C., uniform transparent photosensitive resin composition having an acid value of 77 mgKOH / g and (D-1).

<Examples 2 to 7>
Photosensitive resin compositions (D-2) to (D-7) were obtained in the same manner as in Example 1 except that the compositions shown in Table 2 were changed.

<Comparative Example 1>
Unsaturated polyurethane prepolymer with 50.0 parts by weight of unsaturated polyester polyol (PES-4), 40.0 parts by weight of ASA, 10.0 parts by weight of BPDA, 2.0 parts by weight of HCHP, and 0.2 parts by weight of BHT Each was charged in a container and stirred at about 60 ° C. for 1 hour to obtain a uniformly transparent photosensitive resin composition (D-8) having an acid value of 103 mgKOH / g.

<Comparative Examples 2-8>
Except having changed into the composition shown in Table 2, it carried out similarly to Example 1, and obtained photosensitive resin composition (D-9)-(D-15).

<Comparative Example 9>
Synthesis was performed according to Example 1 of Patent Document 3 (Japanese Patent Laid-Open No. 6-43639) to obtain a uniform transparent liquid resin. This is designated as photosensitive resin composition (D-16).

The photosensitive resin compositions (D-1) to (D-16) obtained as described above were evaluated for basic physical properties of the following photosensitive resin for producing a relief printing plate. The results are shown in Table 3.

(Evaluation of basic physical properties of photosensitive resin for letterpress production)
<Resin acid value, hydroxyl value>
According to JIS K0070.

<Measurement of rubber hardness of cured product>
A PET film having a thickness of 100 μm was adhered to a horizontally placed glass plate, and the photosensitive resin composition obtained thereon was applied to a thickness of 40 mm × 40 mm and a thickness of 3 mm. A PET film having a thickness of 25 μm was overlaid and cured by exposure for 10 minutes using a chemical lamp (illuminance of about 3 mW / cm ² ) having a center wavelength of 360 nm. Thereafter, two cured products obtained by removing the PET film were stacked and measured according to JIS K6253 “Rubber hardness test method”.

<Measurement of weight increase rate of cured product with respect to anisole, isopropyl alcohol, and water>
Using the photosensitive resin composition, create a cured product in the same manner as in the above-mentioned “Measurement of rubber hardness of cured product”, soak it in anisole, isopropyl alcohol, and water at 25 ° C. for 24 hours, and then adhere to the surface. The weight increase rate of anisole, isopropyl alcohol, and water from the change in weight before and after immersion was determined by wiping off the droplets and measuring the weight.

Explanation of abbreviations in Table 2 ASA is 2-acryloyloxyethyl succinic acid (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK ester A-SA, acid value 257 mgKOH / g), MPA is 2-methacryloyloxyethylphthalic acid (Mitsubishi) Made by Rayon Co., Ltd., trade name acrylate PA, acid value 200 mgKOH / g), MAA is methacrylic acid (acid value 651 mgKOH / g), HEMA is 2-hydroxyethyl methacrylate, BPDA is ethylene oxide modified (4 mol adduct) Bisphenol A diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name Light Acrylate BP-4EA), PEGD represents polyethylene glycol (average molecular weight 400) dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK ester 9EG).

As is clear from the results in Table 3, the cured products obtained by photocuring the photosensitive resin compositions obtained in Examples 1 to 7 were flexible with rubber hardness of Shore A 90 ° or less, anisole, isopropyl alcohol, and The weight increase rate of water is as low as 10% or less, and it has excellent resistance to aromatic solvents, alcohol solvents, and water.

On the other hand, in Comparative Example 1 in which the prepolymer was an unsaturated polyester polyol, the rubber hardness was as soft as Shore A 78 °, but the weight increase rate of anisole was as high as 35.0%, and the resistance to aromatic solvents was insufficient. It was.

In Comparative Example 2 in which the ethylenically unsaturated monomer (b1) having a carboxyl group in the molecule represented by the general formula (1) is not used as the ethylenically unsaturated monomer, the rubber hardness is as high as Shore A 95 °, The weight increase rate of anisole was as high as 20.0%, and the resistance to aromatic solvents was insufficient. Furthermore, in Comparative Example 3 using methacrylic acid as a representative example of a monomer having a carboxyl group in the molecule, the rate of increase in the weight of anisole was as low as 5.0%, but the rubber hardness was as high as 98 ° Shore A or higher. It could not be used as a letterpress.

In Comparative Example 4, since the resin acid value was as high as 182 mgOH / g, the rubber hardness was as high as Shore A 98 °. Furthermore, in Comparative Example 5, since the amount of prepolymer used was large, the weight increase rate of anisole was as high as 25.0%, and the resistance to aromatic solvents was low. In Comparative Example 6 where the amount of prepolymer used was small, the weight increase rate of anisole was as low as 3.0%, but the rubber hardness was as high as 95 ° Shore A.

In Comparative Example 7 in which the unsaturated polyester polyol was a saturated polyester polyol, the rubber hardness was suitable as Shore A 80 °, but the weight increase rate of anisole was as high as 21.3%, and the unsaturation without using polyethylene glycol. Also in the comparative example 8 made into the polyester polyol, the weight increase rate of anisole was as high as 22.0%, and the tolerance with respect to an aromatic solvent was inadequate.

In Comparative Example 9, the rubber hardness was as high as Shore A 98 °, the weight increase rate of anisole was as high as 18.0%, and the resistance to the aromatic solvent was insufficient.

According to the present invention, it is suitable for producing a relief printing plate having an appropriate rubber hardness necessary for relief printing and having resistance to an ink using an aromatic solvent, an alcohol solvent, and water. A photosensitive resin composition for producing a relief printing plate can be provided.

Claims (2)

In the photosensitive resin composition for letterpress production (D) containing the prepolymer (A), the ethylenically unsaturated monomer (B), and the photopolymerization initiator (C), all of the following [1] to [6] A photosensitive resin composition for producing a relief plate, characterized by satisfying.
[1] The prepolymer (A) is an unsaturated polyester polyol (a1) obtained by polycondensation of a polyhydric alcohol and a polycarboxylic acid, a polyisocyanate (a2), a functional group having active hydrogen, and ethylene. It is an unsaturated polyurethane prepolymer obtained by reacting at least the compound (a3) having both of unsaturated unsaturated bonds in the molecule.
[2] The unsaturated polyester polyol (a1) is an unsaturated polyester polyol having at least polyethylene glycol as a polyhydric alcohol component and at least an aliphatic unsaturated dicarboxylic acid as an essential component as a polyvalent carboxylic acid component.
[3] The ethylenically unsaturated monomer (B) contains at least a monomer (b1) represented by the following general formula (1).
(In the formula, R ¹ is H or CH ₃ , R ² is an alkylene group having 2 to 5 carbon atoms, n is 1 to 4, R ³ is an alkylene group having 2 to 8 carbon atoms, the following general formula (2), General formula (3) is shown.)
[4] The weight ratio of the prepolymer (A) to the ethylenically unsaturated monomer (B) is in the range of 30 to 70/70 to 30.
[5] The acid value of the photosensitive resin composition (D) for producing a relief printing plate is in the range of 50 to 150 mgKOH / g.
[6] A cured product obtained by photopolymerizing the photosensitive resin composition (D) for producing a relief plate,
(1) Shore A 60-90 ° in JIS rubber hardness, and
(2) The weight increase rate when immersed in anisole, isopropyl alcohol and water at 25 ° C. for 24 hours is 15% or less. The unsaturated polyester polyol (a1) is used in an amount of 40 to 70% by weight of polyethylene glycol based on the total weight of the polyhydric alcohol component and polycarboxylic acid component used in the condensation polymerization, and is ethylenic. The photosensitive resin composition for producing a relief printing plate according to claim 1, wherein the unsaturated bond concentration is in the range of 0.5 to 3.0 mmol / g.