JP4679109B2 - Method for producing negative photosensitive lithographic printing plate - Google Patents

Description

  The present invention relates to a method for producing a lithographic printing plate, and more particularly to a method for producing a negative photosensitive lithographic printing plate that has photosensitivity and forms an image. More specifically, the present invention relates to a method for producing a negative photosensitive lithographic printing plate produced by applying and drying a coating liquid containing a large amount of a highly volatile organic solvent.

  In general, a negative photosensitive lithographic printing plate having an aluminum plate as a support is obtained by applying a photosensitive composition on the support, exposing to exposure to activating light through a negative, etc., curing the exposed area, and using a developer. A cured coating having an oleophilic surface is formed on an aluminum support having a hydrophilic surface by dissolving and removing the unexposed portion while leaving the exposed portion.

  As the above-mentioned photosensitive composition, a combination of a diazo resin and a polymer compound is widely used. By Yonezawa Teruhiko, “Introduction to PS Version” (published by the Printing Society of Japan), Mototaro Nagamatsu and Hideo Inui. , “Photosensitive polymer” (published by Kodansha), Ayao Yamaoka, Mototaro Matsunaga, “Photopolymer Technology” (published by Nikkan Kogyo), etc.

  Further, various companies have proposed CTP systems that directly expose image data on a printing plate by using a laser beam directly without interposing a film by the progress of computers in recent years. For example, as disclosed in JP-A-7-20629, JP-A-7-271029, etc., an infrared absorber is subjected to photothermal conversion, and the exposed portion is locally heated to a high temperature. A lithographic printing plate in which an image portion is formed by crosslinking a resin and a novolac resin. Further, there are lithographic printing plates utilizing a photopolymerization reaction containing a polymerization initiator, a photosensitizing dye, and a polymerizable monomer, which are described in “Printing Magazine”, vol. 78, p. 9, 1995.

  However, the above-described photosensitive lithographic printing plate has a problem that it is difficult to ensure stability such as sensitivity and long-term storage stability. For this reason, the oxygen barrier property is enhanced on the upper part of the photosensitive layer, and surface scratches are prevented. It is common practice to provide an overlayer made of the desired polyvinyl alcohol or the like. Due to the presence of such an over layer, there is a problem of deterioration in image quality due to light scattering during laser exposure, and when developing, a pre-water washing step for removing the over layer is required prior to alkali development. In addition, there is a problem in that a process for applying an overlayer is necessary after the photosensitive layer is applied.

  In order to improve these problems, there is no overlayer, polymerization initiator, dye sensitizer and polymerizable compound, polymerization by radicals generated from the polymerization initiator with light energy absorbed by the dye sensitizer JP-A-2001-290271 (Patent Document 1), JP-A-2001-272778, (Patent Document 2), and JP-A-2002-28734 (Patent Document 3) as techniques using polymerization of a functional compound. A photosensitive composition containing a polymer having a phenyl group substituted with a vinyl group in the side chain, a photo radical generator, and a sensitizing dye is disclosed. It is difficult to produce a lithographic printing plate using such a high-sensitivity photosensitive composition with stable quality with good sensitivity, non-image area elution, printing durability as printing performance, and stain resistance. In particular, in organic solvent-based coating and drying, the evaporation rate is fast, and a non-uniform coated surface is often formed before being conveyed to the drying process. A non-uniform coating surface is an important issue that leads to quality fluctuations. One reason for the formation of a non-uniform coating surface is that the latent heat of vaporization of the organic solvent can lower the temperature of the coating film and cause moisture in the coating atmosphere to condense on the coating film. As a method for avoiding the phenomenon, it has been generally performed to use a solvent having a high boiling point. However, the use of a high boiling point solvent, on the contrary, promotes uneven blown air due to the drying air in the drying process, resulting in a failure to obtain a uniform coating surface, and slowing the drying speed, thus reducing productivity. Problems such as

In order to improve this productivity, measures to increase the drying temperature are taken, but by using high-temperature drying, a negative photosensitive lithographic printing plate in which the exposed area becomes an image and the unexposed area becomes a non-image area, in particular. In this case, it is often observed that the elution property and the storage property of the non-image area are affected. Moreover, the range of drying conditions for obtaining good performance is narrowed by high-temperature drying, resulting in poor production stability.
JP 2001-29071 A JP 2001-272778 A JP 2002-28734 A

  The present invention provides a negative photosensitive lithographic printing plate in which a photosensitive layer containing at least a polymer having a polymerizable double bond in a side chain and a polymerization initiator is provided on an aluminum support. It is an object of the present invention to provide a method for efficiently producing a negative photosensitive lithographic printing plate having good printability and dirtiness and having a uniform coated surface and having a stable quality.

  The above object of the present invention has been achieved by the following means.

1) A photosensitive layer containing at least a polymer having a polymer having a phenyl group substituted with a vinyl group as a polymerizable double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component on an aluminum support. In the method for producing a negative photosensitive lithographic printing plate provided, 80% by mass or more of the organic solvent that is the solvent of the photosensitive layer coating solution is an organic solvent having a boiling point of less than 110 ° C., and the application of the photosensitive layer coating solution A process for producing a negative photosensitive lithographic printing plate, wherein the process satisfies the following conditional expression 1 and the drying process satisfies the following conditional expression 2.
T1-T2> −18 (° C.) Formula 1
T1−T3 <30 (° C.) Formula 2
In the formula, T1 represents the surface temperature (° C.) of the photosensitive layer coated on the aluminum support, T2 represents the dew point (° C.) of the coating process, and T3 represents the average boiling point of the organic solvent having a boiling point of less than 110 ° C. Represents.

  2) The method for producing a negative photosensitive lithographic printing plate as described in 1) above, wherein the photosensitive layer further contains a polymerizable monomer.

  3) The method for producing a negative photosensitive lithographic printing plate as described in 1) or 2) above, wherein the time for applying the photosensitive layer coating solution is from 3 seconds to 20 seconds.

  4) The method for producing a negative photosensitive lithographic printing plate as described in 1), 2) or 3) above, wherein the substrate is heated at a temperature before coating and the temperature is higher than the environmental temperature for coating the coating solution on the substrate.

  5) The method for producing a negative photosensitive lithographic printing plate as described in 1), 2), 3) or 4) above, wherein the substrate after coating is heated to a temperature higher than the environmental temperature at which the coating solution is applied onto the substrate. .

  6) The method for producing a negative photosensitive lithographic printing plate as described in 1), 2), 3), 4) or 5) above, wherein the temperature of the coating solution is higher than the environmental temperature at which the coating solution is applied onto the support. .

  According to the present invention, in a method for producing a negative photosensitive lithographic printing plate in which a photosensitive layer containing at least a polymer having a polymerizable double bond in a side chain and a polymerization initiator is provided on an aluminum support, the printing performance is improved. It is possible to efficiently produce a negative photosensitive lithographic printing plate having good printability and stain resistance and having a uniform coated surface and a stable quality.

The present invention will be described in detail below.
In the production process of a negative lithographic printing plate in which the photosensitive layer of the present invention is provided on an aluminum support, the surface temperature (T1) of the photosensitive layer coated on the aluminum support in the coating process and the environment of the coating process It has been found that the difference (T1-T2) from the dew point (T2) affects the coated surface of the coated photosensitive layer. That is, when the difference between T1 and T2 becomes larger on the minus side, the coated surface becomes non-uniform, and accordingly, the above problem can be solved by reducing the difference on the minus side (T1-T2> −18 ° C.). .

  In Formula 1 of the present invention, T1-T2> −15 ° C. is preferable, and T1-T2> −10 ° C. is more preferable.

  The photosensitive layer coating solution of the present invention contains an organic solvent having a boiling point of less than 110 ° C. in an amount of 50% by mass or more. When a coating liquid containing such a highly volatile organic solvent in a high ratio is applied on an aluminum support, the above-described problems are likely to occur. That is, the surface temperature (T1) of the coated photosensitive layer is lowered due to the latent heat of vaporization of the highly volatile organic solvent, resulting in a phenomenon in which the surface temperature drops below the dew point (T2) of the coating process. When the difference between T1 and T2 increases to the minus side, moisture in the atmosphere of the coating process is condensed and attached on the coating surface of the photosensitive layer, resulting in a difference in drying speed between the portion where moisture has adhered and other regions. I think this may be a factor that causes surface non-uniformity.

  In the present invention, the dew point of the coating process represented by T2 is the dew point of the atmosphere up to the place where the coating apparatus is installed and the entrance of the drying process (drying dryer), and the difference between T1 and T2 is the difference in the photosensitive layer. The comparison is made at the same position as the surface temperature (T1).

  The surface temperature (T1) of the photosensitive layer decreases with the lapse of time after coating due to the latent heat of vaporization of the low-boiling organic solvent. On the other hand, the atmosphere in the coating process is usually set to the same atmosphere from the coating installation location to the drying process entrance. Therefore, the difference between T1 and T2 is greatest on the minus side near the entrance of the drying process.

  In the present invention, as means for satisfying the difference between T1 and T2, that is, T1-T2> −18 ° C., a method for suppressing a decrease in the surface temperature (T1) of the photosensitive layer and a dew point (T2) in the coating process are lowered. There are methods and a combination of these methods.

Examples of methods for suppressing the decrease in T1 include the following methods.
1) The temperature of the coating solution for the photosensitive layer is set high in advance.
2) The aluminum support is heated and raised immediately before or immediately after application.
3) Shorten the coating process time. That is, the time from applying the coating solution for the photosensitive layer to entering the drying step is shortened.

The above method will be described more specifically.
1) The temperature of the coating solution for the photosensitive layer is often room temperature, but it is 5 to 10 ° C. higher than the dry bulb temperature in the coating process. That is, it is set to 25 to 40 ° C.
2) The temperature of the aluminum support is heated by a heating means such as a heating roller so that the temperature becomes 25 to 50 ° C. immediately before or after application.
3) Set the coating process time to be within 20 seconds. The lower limit time is about 3 seconds.

  The present invention must satisfy the above-described conditional expression 2 also in the drying step. That is, if the difference between the surface temperature (T1) of the photosensitive layer in the drying step and the average boiling point (T3) of the organic solvent having a boiling point of less than 110 ° C. contained in the coating solution becomes too large, a lithographic printing plate is obtained. It has been found that the above-mentioned problems can be solved by making the above difference smaller than 30 ° C., because the printing performance (printing durability, stain resistance, etc.) is not stably obtained at a high level.

  That is, in the drying process, the surface temperature (T1) of the photosensitive layer rises as the applied photosensitive layer is dried, and rises to almost the same as the dry bulb temperature of the drying air near the end of drying. Therefore, in the general drying process, the surface temperature (T1) of the photosensitive layer near the end of drying is the highest. The photosensitive layer of the present invention, that is, a polymer having a polymerizable double bond in the side chain and having a carboxyl group-containing monomer as a copolymerization component, a photopolymerization initiator, and a low boiling point organic solvent in a high ratio In the photosensitive layer, it was found that a printing plate having a high level of printing performance (printing durability and stain resistance) can be stably produced by making the difference between T1 and T3 less than 30 ° C. In particular, not only immediately after production but also after long-term storage, the elution of the non-image area was improved, and as a result, the stain resistance was improved.

In conditional expression 2, T3 represents the average boiling point of the organic solvent below 110 ° C. That is, when there is only one kind of the organic solvent, it is the boiling point of the organic solvent, but when two or more kinds are used in combination, it is a numerical value calculated in consideration of the content ratio (mass ratio).
For example, when the organic solvent having a boiling point of 90 ° C. contains 60% by mass of the total organic solvent having a boiling point of less than 110 ° C. and 40% by mass of the organic solvent having a boiling point of 70 ° C., the average boiling point is as follows: So ask.
90 ° C x 0.6 + 70 ° C x 0.4 = 82 ° C

  In the present invention, the photosensitive layer preferably further contains a polymerizable monomer, whereby a lithographic printing plate having high sensitivity and high printing durability can be obtained, but its plate surface and elution property after storage are deteriorated. Therefore, the production method of the present invention is effective in a system further containing a polymerizable monomer.

  As described above, the intended purpose of the present invention can be achieved only by combining conditional expressions 1 and 2. That is, if only the conditional expression 1 is satisfied, the ratio of the organic solvent below 110 ° C. may be reduced, and the latent heat of vaporization may be suppressed by using a coating liquid using a large amount of high-boiling organic solvent, Then, it becomes necessary to perform high temperature drying, and it becomes difficult to stably produce a high sensitivity negative photosensitive lithographic printing plate. Therefore, in the production process of a high-sensitivity negative photosensitive lithographic printing plate containing 50% by mass or more of an organic solvent having a boiling point of less than 110 ° C., a coating process and a drying process of the photosensitive layer coating solution satisfying both formulas 1 and 2 Solve these problems.

  In the present invention, the composition of the photosensitive layer provided on the aluminum support will be described in detail later, but at least a polymer having a polymerizable double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component, and It contains a photopolymerization initiator, and preferably further contains a polymerizable monomer. Furthermore, a sensitizing dye, a polymerization inhibitor, a surfactant, a color pigment, and the like are added as necessary. Accordingly, the coating solution for the photosensitive layer contains the above-described chemicals in a state dissolved or dispersed in an organic solvent.

  The concentration of all the above-mentioned drugs in the coating solution is prepared at a concentration of about 5 to 30% by mass. Among them, the polymer concentration is preferably 1 to 25% by mass. The dry film thickness of the photosensitive layer is preferably formed in the range of 0.5 to 10 μm, particularly preferably in the range of 1 to 5 μm. Therefore, the coating amount of the coating solution is set from the preset thickness of the photosensitive layer and the polymer concentration in the coating solution.

  Examples of the coating method include roll coating, dip coating, air knife coating, gravure coating, hopper coating, blade coating, and wire doctor coating.

  The organic solvent having a boiling point of less than 110 ° C. containing 50% by mass or more of the total organic solvent used in the coating liquid of the present invention is particularly limited as long as it is an organic solvent having a boiling point of less than 110 ° C. under atmospheric pressure. Can be used instead of things. For example, acetone, methyl ethyl ketone, methanol, ethanol, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, cyclohexane, methyl acetate, ethyl acetate and the like can be mentioned. Particularly preferred organic solvents include tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane. It is necessary to contain 50% by mass or more with respect to the total organic solvent, preferably 70% by mass or more, and more preferably 80% by mass or more.

  In addition to the organic solvent, it is one of the preferred embodiments to contain a high boiling point solvent of 110 ° C. or higher depending on various purposes such as the stability of the dispersion in the coating liquid and the coating surface stability aid. For example, N.A. N dimethylformamide, cyclohexanone, ethylene glycol monoethyl ether and the like are preferably used. However, a large amount remaining in the photosensitive layer is not preferable because it causes deterioration of storage stability with time and deterioration of printing durability as printing performance as described above. The content needs attention and is preferably 30% by mass or less, more preferably 20% or less of the total organic solvent.

  About the support body used for this invention, it is the aluminum plate which is grind | polished and has an anodized film, and the aluminum support body generally used for a lithographic printing plate is used. In general, an aluminum support used for a lithographic printing plate is a surface roughened in order to improve wettability (water retention) against dampening water during printing and to improve adhesion to the photosensitive layer. Is done. This roughening treatment (so-called graining) is performed by mechanically roughening treatment such as ball graining, wire graining or brush graining, or by chemically dissolving aluminum with chloride, fluoride or the like. A chemical surface roughening treatment, an electrolytic surface roughening treatment performed by electrochemically dissolving aluminum, and a surface roughening method using these methods in combination are known. For example, JP-A 48-28123, 53-123204, 54-146234, 55-25381, 55-132294, 56-55291, 56-150593, 56-28893, No. 58-167196, U.S. Pat. Nos. 2,344,510, 3,861,917, and 4,301,229. Regarding the surface shape of the aluminum plate, U.S. Pat. No. 2,344,510 is a grained structure in which mechanical roughening and electrolytic roughening are combined and superimposed, and U.S. Pat. No. 4,301,229 is pit. Cumulative frequency distribution of diameters and centerline average roughness, US Pat. No. 3,861,917 is the depth of the rough surface, Canadian Patent No. 955449 is the height and diameter of the rough surface, West German Patent 1,813, No. 443 describes the level difference of the rough surface. After such surface roughening treatment, anodization treatment is performed in an electrolytic solution such as sulfuric acid, phosphoric acid, nitric acid or a mixture thereof.

  The polymer having a polymerizable double bond in the side chain and having a carboxyl group-containing monomer as a copolymerization component used in the present invention will be described. As the carboxyl group-containing monomer, acrylic acid, methacrylic acid, acrylic acid 2-carboxyethyl ester, methacrylic acid 2-carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, Examples include 4-carboxystyrene and the like.

  As monomers for introducing a polymerizable double bond into the polymer side chain, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl-acrylate, 1-propenyl-methacrylate, β-phenyl-vinyl- Methacrylate, β-phenyl-vinyl-acrylate, vinyl methacrylamide, vinyl acrylamide, α-chloro-vinyl-methacrylate, α-chloro-vinyl-acrylate, β-methoxy-vinyl-methacrylate, β-methoxy-vinyl-acrylate, vinyl -Thio-acrylate, vinyl-thio-methacrylate and the like.

  Particularly preferred as the polymer used in the present invention is a polymer having a phenyl group substituted with a vinyl group as a polymerizable double bond in the side chain and a carboxy group-containing monomer as a copolymerization component. The phenyl group substituted with a vinyl group is bonded to the main chain directly or through a linking group, and the linking group is not particularly limited, and includes any group, atom, or a combination thereof. The phenyl group may be substituted with a substitutable group or atom, and the vinyl group is a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, It may be substituted with an aryl group, an alkoxy group, an aryloxy group or the like. More specifically, the polymer having a phenyl group in which a vinyl group is substituted on the side chain described above has a group represented by the following chemical formula 1 in the side chain.

In the formula, Z ₁ represents a linking group, and R ₁ , R ₂ , and R ₃ are a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, and an aryl group. A group, an alkoxy group, an aryloxy group, and the like, and these groups may be substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, or the like. R ₄ represents a substitutable group or atom. n ₁ represents 0 or 1, m ₁ represents an integer of 0 to 4, and k ₁ represents an integer of ₁ to 4.

The above general formula will be described in more detail. As the linking group for Z ₁ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₅ ) —, —C (O) —O—, —C (R ₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, and a group represented by the following chemical formula 2 alone or in combination of two or more. Here, R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole ring, indole ring. , Indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring, and the like, and a substituent may be bonded to these heterocyclic rings.
Although the example of group represented by Chemical formula 1 is shown below, it is not limited to these examples.

Among the groups represented by the above chemical formula 1, preferred ones exist. That is, it is preferable that R ₁ and R ₂ are hydrogen atoms and R ₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.). Furthermore, as the linking group for Z ₁ , those containing a heterocyclic ring are preferred, and those in which k ₁ is 1 or 2 are preferred.

  Examples of polymers having a group represented by Chemical Formula 1 and having a carboxy group-containing monomer as a copolymerization component are shown below. In the formula, the number represents the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  The polymer of the present invention may further contain another monomer as a copolymer component. Other monomers include styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, methyl methacrylate, Methacrylic acid alkyl esters such as ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and dodecyl methacrylate, aryl methacrylates or alkylaryl esters such as phenyl methacrylate and benzyl methacrylate , 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monoester methacrylate, methoxyethylene methacrylate Methacrylic acid esters having an alkyleneoxy group such as glycol monoester and methacrylic acid polypropylene glycol monoester, amino group-containing methacrylic acid esters such as 2-dimethylaminoethyl methacrylate and 2-diethylaminoethyl methacrylate, or acrylic acid esters Examples of these corresponding methacrylic acid esters, or monomers having a phosphoric acid group such as vinylphosphonic acid, amino group-containing monomers such as allylamine and diallylamine, or vinylsulfonic acid and its salts, allylsulfone Monomers having a sulfonic acid group such as acid and its salt, methallylsulfonic acid and its salt, styrenesulfonic acid and its salt, 2-acrylamido-2-methylpropanesulfonic acid and its salt As monomers having a nitrogen-containing heterocyclic ring such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or monomers having a quaternary ammonium base, 4-vinylbenzyltrimethylammonium chloride, acryloyloxyethyl Trimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, or acrylonitrile, methacrylonitrile, Acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropyl acrylate Acrylamide or methacrylamide derivatives such as amide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, chloroacetic acid Vinyl esters such as vinyl, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, and vinyl ethers such as methyl vinyl ether and butyl vinyl ether, N-vinyl pyrrolidone, acryloyl morpholine, tetrahydrofurfuryl methacrylate, vinyl chloride , Various monomers such as vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, glycidyl methacrylate, etc. And the like.

  There is a preferable range for the molecular weight of the polymer according to the present invention, and the mass average molecular weight is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 5,000 to 500,000.

  As the polymerization initiator of the present invention, any compound can be used as long as it is a compound capable of generating radicals by light irradiation. For example, trihaloalkyl-substituted compounds (for example, triazine compounds and oxadiazole derivatives as trihaloalkyl-substituted nitrogen-containing heterocyclic compounds, trihaloalkylsulfonyl compounds), hexaarylbisimidazoles, titanocene compounds, ketoxime compounds, thio compounds, organic compounds A peroxide etc. are mentioned. Among these photopolymerization initiators, organic boron salts are preferably used, and more preferably, organic boron salts and trihaloalkyl-substituted compounds are used. As the organic boron salt preferably used, a compound having an organic boron anion represented by Chemical formula 12 is used.

In the chemical formula 12, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ may be the same or different, and may be an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocyclic group. Represents. Of these, it is particularly preferred that one of R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ is an alkyl group and the other substituent is an aryl group.

  As said organic boron salt, it is a salt containing the organic boron anion represented by the chemical formula 12 shown previously, and an alkali metal ion and an onium compound are preferably used as a cation which forms a salt. Particularly preferable examples of the onium salt with an organic boron anion include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts. Examples of particularly preferred organic boron salts are shown below.

  There is a preferable range for the proportion of the organic boron salt in the photosensitive layer, and the organic boron salt is preferably contained in the range of 0.1 to 50 parts by mass in 100 parts by mass of the photosensitive layer. .

  A preferred polymerization initiator used in combination with the organic boron salt according to the present invention is a trihaloalkyl-substituted compound. The trihaloalkyl-substituted compound mentioned here is specifically a compound having at least one trihaloalkyl group such as a trichloromethyl group or a tribromomethyl group in the molecule, and preferred examples include the trihaloalkyl group. Examples of the compound bonded to the nitrogen heterocyclic group include s-triazine derivatives and oxadiazole derivatives, or a trihaloalkylsulfonyl compound in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocyclic ring via a sulfonyl group. Can be mentioned.

  Particularly preferred examples of trihaloalkyl-substituted nitrogen-containing heterocyclic compounds and trihaloalkylsulfonyl compounds are shown below.

  When a trihaloalkyl-substituted compound is used, there is a preferred range in the photosensitive layer of the photosensitive lithographic printing plate, and the proportion in the total 100 parts by mass of the photosensitive layer is 0.1 to 50 parts by mass. It is preferably included in the range of parts. Further, these are preferable because the sensitivity is particularly improved when they are contained in the photosensitive layer together with the above-described organic boron salt. In this case, the ratio to the organic boron salt is trihaloalkyl substitution with respect to 1 part by mass of the organic boron salt. The compound is preferably contained in the range of 0.1 to 50 parts by mass.

  The photosensitive layer of the negative photosensitive lithographic printing plate of the present invention preferably contains a polymerizable monomer. By combining this, a higher sensitivity can be realized, and a lithographic printing plate excellent in printing performance can be obtained.

  Examples of the polymerizable monomer include polymerizable compounds having a polymerizable double bond. Examples of preferred polymerizable monomers include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanurate, tripropylene glycol diacrylate. Examples thereof include polyfunctional acrylic monomers such as acrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate.

  Alternatively, an oligomer having radical polymerizability is preferably used in place of the above-described polymerizable compound, and polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, etc. as various oligomers into which acryloyl group or methacryloyl group is introduced Are also used in the same manner, but these can also be preferably used as ethylenically unsaturated compounds.

  A more preferable embodiment of the polymerizable monomer includes a polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule. When this compound is used, crosslinking is effectively carried out by recombination of styryl radicals generated by the generated radicals, which is extremely preferable for producing a highly sensitive negative photosensitive lithographic printing plate.

  A polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule is typically represented by the following general formula.

In the formula, Z ₂ represents a linking group, and R ₂₁ , R ₂₂ and R ₂₃ are a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, and an aryl group. An alkoxy group, an aryloxy group, and the like, and these groups may be substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, or the like. R ₂₄ represents a substitutable group or atom. m ₂ represents an integer of 0 to 4, and k ₂ represents an integer of 2 or more.

Further details will be described. As the linking group for Z ₂ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₂₅ ) —, —C (O) —O—, —C (R ₂₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₂₅ and R ₂₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

  Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole ring, indole ring. , Indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring and the like, and a substituent may be bonded to these.

Among the compounds represented by the formula 17, there are preferable compounds. That is, R ₂₁ and R ₂₂ are hydrogen atoms, R ₂₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k ₂ is preferably a compound having 2-10. Specific examples of the compound represented by Chemical Formula 17 are shown below, but the invention is not limited to these examples.

  There is a preferred range for the proportion of the polymerizable monomer as described above in the photosensitive layer of the negative photosensitive lithographic printing plate, and the polymerizable monomer is 1 to 60 parts by mass in 100 parts by mass of the photosensitive layer. It is preferable that it is contained in the range of 5 mass parts to 50 mass parts.

  It is preferable to add a sensitizing dye to the photosensitive layer of the negative photosensitive lithographic printing plate of the present invention. As the sensitizing dye to be added, those which sensitize the decomposition of the polymerization initiator in a wavelength range of 380 nm to 1300 nm, and various cationic dyes, anionic dyes and neutral dyes having no charge include merocyanine and coumarin. , Xanthene, thioxanthene, azo dyes and the like can be used. Among these, particularly preferable examples are dyes selected from cyanine, carbocyanine, hemicyanine, methine, polymethine, triarylmethane, indoline, azine, thiazine, xanthene, oxazine, acridine, rhodamine, and azamethine dyes as cationic dyes. It is. In combination with these cationic dyes, they are preferably used because of their particularly high sensitivity and excellent storage stability. Furthermore, in recent years, an output machine (plate setter) equipped with a violet semiconductor laser having an oscillation wavelength in the range of 380 to 410 nm has been developed. As a photosensitive system having high sensitivity corresponding to this output machine, a system containing a pyrylium compound or a thiopyrylium compound as a sensitizing dye is preferable. Examples of preferred sensitizing dyes according to the present invention are shown below.

  Examples particularly preferred as a sensitizing dye in a system for imparting photosensitivity to light in the near infrared to infrared wavelength region of 750 nm or more are shown below.

  There is a preferred range in the quantitative ratio of the sensitizing dye and the polymerization initiator as described above. The photopolymerization initiator is preferably used in the range of 0.01 parts by weight to 100 parts by weight with respect to 1 part by weight of the sensitizing dye, more preferably in the range of 0.1 parts by weight to 50 parts by weight. Is preferably used.

  The photosensitive layer of the photosensitive lithographic printing plate of the present invention preferably contains a colorant. It is used for improving the visibility of the image area, and more preferably has absorption in the visible light region in order to improve the safelight property. It is also preferable to contain a colorant in the photosensitive wavelength region for improving the image quality. Examples of these colorants include inorganic pigments, organic pigments, and dyes as described below.

  Examples of inorganic pigments include mica-like iron oxide, red lead, yellow lead, silver vermilion, ultramarine, titanium dioxide, coated mica, stone team chromate, titanium yellow, zinc chromate, molybdenum red, chromium oxide, calcium leadate, and the like. . Organic pigments include carbon black, phthalocyanine pigment, monoazo pigment, disazo pigment, condensed azo pigment, isoindolinone pigment, quinophthalone pigment, nickel azo pigment, perinone pigment, perylene pigment, anthrone pigment, quinacridone pigment, anthraquinone pigment, Examples thereof include thioindigo pigments, dioxazine pigments, indanthrone pigments, and pyranthrone pigments. Examples of the dye include various dyes such as a phthalocyanine dye, a triarylmethane dye, an anthraquinone dye, and an azo dye.

  The above pigments and dyes may be used alone, but two or more of them may be used in combination.

  A polymerization inhibitor can also be preferably added as another element constituting the photosensitive lithographic printing plate. For example, compounds such as quinone and phenol are preferably used, and compounds such as hydroquinone, p-methoxyphenol, catechol, t-butylcatechol, 2-naphthol, and 2,6-di-t-butyl-p-cresol are used. Preferably used. The preferred proportion of these polymerization inhibitors and the aforementioned ethylenically unsaturated compounds is preferably used in the range of 0.001 to 0.1 parts by mass with respect to parts by mass of the ethylenically unsaturated compounds.

  As the developer of the present invention, any aqueous alkaline solution can be used as long as the pH is 8 or more. Examples of the alkali agent include sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, sodium borate, potassium borate, ammonium borate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, Inorganic alkaline agents such as potassium carbonate, ammonium carbonate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, trisodium phosphate, tribasic potassium phosphate and tribasic ammonium phosphate, monomethylamine , Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine , Monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-ethylethanolimine, Nn-butylethanolamine, Nt-butylethanolamine, Nn-butyldiethanolamine, Nt-butyldiethanolamine N-methylethanolamine, N-methyldiethanolamine, N-aminoethylethanolamine, N-aminoethylpropanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Examples include organic alkali agents, alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate, and ammonium silicate. These can be used alone or in combination of two or more.

  The developer used in the present invention can be used in combination with other various surfactants, and examples thereof include anionic, cationic, nonionic and amphoteric surfactants. These surfactants used in combination are added to the developer in the range of 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

  Various development stabilizers can be used in the developer used in the present invention. Preferred examples thereof include polyethylene glycol adducts of sugar alcohols described in JP-A-6-282079, phosphonium salts such as tetrabutylphosphonium bromide, and iodonium salts such as diphenyliodonium chloride. Furthermore, anionic surfactants or amphoteric surfactants described in JP-A-50-51324, water-soluble cationic polymers described in JP-A-55-95946, and JP-A-56-142528 are described. There are water-soluble amphoteric polyelectrolytes that have been described. Further, an organic boron compound to which an alkylene glycol is added as described in JP-A No. 59-84241, a polyethylene glycol having a weight average molecular weight of 300 or more as described in JP-A No. 61-215554, and a cation as described in JP-A No. 63-175858. And a fluorine-containing surfactant having a functional group, a water-soluble ethylene oxide adduct obtained by adding 4 mol or more of an acid or an alcohol or an alcohol disclosed in JP-A-2-39157, and a water-soluble polyalkylene compound.

  It is advantageous in terms of transportation that the developer used in the present invention is a concentrated solution in which the water content is less than that in use, and is diluted with water at the time of use. The degree of concentration in this case is suitably such that each component does not cause separation or precipitation, and depending on the content, it can usually be concentrated to about concentrate: water = 1: 0 to 1:10. In addition, since the container is alkaline, it is preferable to use a material that does not permeate carbon dioxide and that does not break during transportation for safety. Usually, a resin container such as a hard bottle or a cubicener is preferably used.

  In the processing method of the present invention, the processing is performed with a normal automatic processor after exposure. The automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray tank, and is assembled by a pump while horizontally transporting the exposed printing plate. Each processing solution is sprayed from a spray nozzle to develop and post-process. Recently, a developing method has been developed in which a printing plate is dipped and conveyed by a submerged guide roll in a developing tank filled with a developing solution, and such a developing method can also be suitably applied to the present invention. . Such an automatic developer can be processed while replenishing the replenisher according to the development processing amount, operating time, and the like.

  The printing plate developed with the developer having such a composition is subjected to post-processing with a washing water, a rinse solution containing a surfactant, a finisher mainly composed of gum arabic or starch derivatives, or a protective gum solution. The In the post-treatment of the printing plate of the present invention, these treatments can be used in various combinations. For example, development → water washing → rinsing liquid treatment containing surfactant or development → water washing → finisher liquid treatment is a rinse liquid or finisher. Less liquid fatigue is preferable. Furthermore, a countercurrent multistage process using a rinse liquid or a finisher liquid is also a preferred embodiment. These post-processing are generally performed using an automatic developing machine including a developing unit and a post-processing unit. As the post-treatment liquid, a method of spraying from a spray nozzle or a method of conveying through a treatment tank filled with the treatment liquid is used. A method is also known in which a small amount of aqueous water is supplied to the plate surface after development and washed with water, and the waste solution is reused as dilution water for the developer stock solution. In such automatic processing, each processing solution can be processed while being replenished with the respective replenishing solution according to the processing amount and operating time. In addition, a so-called disposable processing method in which treatment is performed with a substantially unused post-treatment liquid can also be applied. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples as well as the effects. The part in an Example shows a mass part and% shows the mass%.

  A photosensitive layer coating solution having the following formulation is prepared as shown in Table 1, and coated on a grained and anodized aluminum plate having a thickness of 0.29 mm so that the dry film thickness is 5 μm. A sample was prepared. The manufacturing conditions are shown in Table 2.

<Coating solution for photosensitive layer>
Polymer (P-1; mass average molecular weight of about 90,000) 30 parts 1,3-dioxolane as a solvent for polymer 70 parts Polymerization initiator (BC-5) 4 parts
(BS-1) 2 parts Polymerizable monomer (C-5) 15 parts Pentaerythritol tetraacrylate 10 parts Sensitizing dye (S-33) 0.4 part Polymerization inhibitor 2,6-di-t-butylcresol 0. 2 parts Solvents listed in Table 1 (parts)
4 parts of carbon black with an average particle size of 185 nm

The support in Table 2 was heated using a heating roller so that the support was 30 ° C. immediately before coating. The drying process temperature (° C.) represents the dry bulb temperature of the drying air. Moreover, the surface temperature of the coating process indicates the result of measurement using a non-contact infrared thermometer.

  The uniformity of the surface of the sample produced as described above was judged visually according to the following evaluation criteria. The results are shown in Table 3.

○: Uniform coating surface ○ △: Almost uniform coating surface, no problem level ×: Non-uniform coating surface

A sample prepared in the same manner as above, using an external drum type plate setter mounted with a 830 nm semiconductor laser, PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd., drum rotation speed 1000 rpm resolution 2400 dpi, laser irradiation energy 100 mJ / cm ² The print test chart image was exposed at. After exposure, Dainippon Screen Mfg. Co., Ltd. PS plate automatic developing machine PD-1310 was used as an automatic developing machine, and the following developing solution was used to carry out the developing process at a liquid temperature of 28 ° C. for 15 seconds, followed by A gum solution having the following formulation was applied.

<Developer>
35% sodium alkylnaphthalene sulfonate
(Surfactant manufactured by Kao Corporation) 30g
KOH 25g
50 g of 20% potassium silicate aqueous solution (containing 20% SiO ₂ ) 50 g
N-aminoethylethanolamine 30g
1L with water
<Gum solution>
1g potassium phosphate 5g
Gum arabic 25g
Dehydroacetic acid 0.5g
EDTA2Na 1g
1L with water

A printing test was performed on the planographic printing plate prepared as described above. As a printing test,
As for stains, the printing press is Heidelberg TOK (trademark of Heidelberg's offset printing press), the ink is FINE INK New Champion Purple S (Dainippon Ink Chemical Co., Ltd.), and the dampening solution is Eu-3 ( Using a 0.5% aqueous solution of a fountain solution for PS plates manufactured by Fuji Photo Film Co., Ltd., we evaluated the scumming of 30,000 printed samples. As for printing durability, Heidelberg TOK (trademark of Heidelberg's offset printing machine) is used as the printing press, ink is BEST ONE black H (manufactured by T & KTOKA), and fountain solution is Astro Mark III (Co., Ltd.). Evaluation was performed using a 1% aqueous solution of dampening water manufactured by Nikken Chemical Research Co., Ltd. The stain resistance and printing durability were evaluated according to the following evaluation criteria and are summarized in Table 3.

Dirtability ○: Extremely good ○ △: Good ×: Whole surface dirt Printing durability ○: 200,000 sheets or more ○ △: 100,000 to 200,000 sheets ×: 50,000 sheets or less

From the above results, sample 1 (comparison) does not satisfy T1-T2> −18 (° C.), so only a non-uniform coated surface can be obtained, and the influence on printing durability is observed. The change in the value of T1-T2 between samples 2 and 3 (both of the present invention) was due to the effect of the coating process time. Sample 3 was 15 seconds, while sample 2 was 25 seconds. Samples 4 and 5 (both of the present invention) have an effect of increasing the temperature of the support before coating and the coating solution, respectively. Samples 6 and 7 (both of the present invention) can be used as a coating liquid containing dew point in a high coating process or tetrahydrofuran having a low boiling point as a main solvent due to the effect of raising the temperature of the support before coating and the coating liquid. A printing plate with good performance was obtained. Sample 8 (invention) produced a sample at a drying temperature of 100 ° C. , but showed satisfactory performance. Sample 9 (comparison) did not satisfy T1-T3 < 30 (° C.), resulting in poor elution of the non-image area and smeared printed matter. Sample 10 (comparative) satisfies T1-T2> −18 (° C.) and T1-T3 < 30 (° C.), but the organic solvent having a boiling point of less than 110 ° C. is less than 50% by mass and is insufficiently dried. The printability was poor.

  From the above results, it can be seen that the present invention provides a uniform coated surface at an efficient coating speed and exhibits stable and good printability.

Claims (1)

A photosensitive layer containing at least a polymer having a polymer having a phenyl group substituted with a vinyl group as a polymerizable double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component was provided on an aluminum support. In the method for producing a negative photosensitive lithographic printing plate, 80% by mass or more of the organic solvent that is the solvent of the photosensitive layer coating solution is an organic solvent having a boiling point of less than 110 ° C., and the coating process of the photosensitive layer coating solution is performed. A method for producing a negative photosensitive lithographic printing plate, wherein the following conditional expression 1 is satisfied, and the drying step satisfies the following conditional expression 2.
T1-T2> −18 (° C.) Formula 1
T1−T3 <30 (° C.) Formula 2
In the formula, T1 represents the surface temperature (° C.) of the photosensitive layer coated on the aluminum support, T2 represents the dew point (° C.) of the coating process, and T3 represents the average boiling point of the organic solvent having a boiling point of less than 110 ° C. Represents.