JP4664256B2 - Image forming composition and photosensitive lithographic printing plate using the same - Google Patents

Description

  The present invention relates to an image forming composition and a photosensitive lithographic printing plate using the same. In particular, the present invention relates to an image forming composition for positive lithographic printing plate for direct plate making which can be directly made from a digital signal of a computer or the like.

  Positive lithographic printing plates for infrared lasers are composed of alkali-soluble resins such as novolak resins and photothermal conversion materials that absorb infrared light and generate heat as the main photosensitive layer components, and the structure of the novolak resin due to the heat generated by infrared irradiation. A direct plate-making method (thermal positive type) and the like have been developed in which an image is formed by increasing the solubility in a developing solution by changing.

  The image forming ability of such a positive lithographic printing plate for infrared laser depends on the heat generated by infrared laser exposure on the surface of the photosensitive layer, so that in the vicinity of the support, as heat is diffused to the support, image formation, That is, the amount of heat used to solubilize the photosensitive layer is reduced, resulting in low sensitivity. Therefore, there is a problem that the effect of disappearing the development inhibiting ability of the photosensitive layer in the non-image area cannot be sufficiently obtained, and the difference between the image area and the non-image area becomes small and the highlight reproducibility is insufficient (patent) Reference 1).

  On the other hand, not the difference in solubility due to the difference in structural change of the novolak resin as described above, but an infrared photosensitive composition utilizing a chemical reaction is also disclosed. For example, the recording material described in Patent Document 2 is composed of an alkali-soluble binder having an infrared absorber, an acid generator, and a group that is decomposed by an acid. Since this recording material is an alkali-soluble binder having 4-hydroxystyrene as a skeleton, the molecular weight is small, and as a result, the alkali solubility of the entire recording material is increased. For this reason, it can be said that the recording material is not suitable for a lithographic printing plate because there is almost no difference between an image area and a non-image area and the development latitude is narrow. Further, this recording material containing an alkali-soluble binder having poor heat resistance due to the 4-hydroxystyrene skeleton causes a significant decrease in sensitivity when stored for several days at a high temperature of 50 ° C. or higher. For this reason, there was a big problem in operating as a printing plate.

Patent Document 3 discloses a photosensitive composition containing an infrared absorber, a photoacid generator, a specific polymer compound, and an alkali-soluble resin. Although this photosensitive composition has high sensitivity and excellent development latitude, the problem of image peeling during development is not solved by rubbing between the interleaf and the photosensitive layer during handling or when using an autoloader. There was room for further improvement.
Japanese Patent Laid-Open No. 10-268512 JP 11-72919 A JP 2004-212752 A

  The present invention has been made in view of the above problems. That is, an object of the present invention is to have a positive-type image forming composition that is highly sensitive to an infrared region such as a semiconductor laser, has a wide development latitude, has high scratch resistance, highlight reproducibility, and high storage stability. The object is to provide a positive photosensitive lithographic printing plate.

The above object of the present invention is to
(A) an alkali-insoluble polymer compound represented by the following general formula (I):
(B) a photoacid generator;
(C) an infrared absorber;
(D) an acid-decomposable polymer compound represented by the following general formula (II) that generates a resin polymer [Polym-OH] having a phenolic hydroxyl group and a decomposed silanol compound by the action of an acid;
(E) An image-forming composition containing an alkali-soluble resin, or a photosensitive lithographic printing plate comprising the image-forming composition provided on a support.

(In the above formula, R ₁ and R ₂ each independently represent hydrogen or a C ₁ -C ₁₂ alkyl group. P in the general formula (I) is capable of dissociating a phenolic hydroxyl group by the action of an acid. Means protecting group.)

(In the general formula (II), two R _{3 s} each independently represent an alkyl group, an alkoxy group, a hydroxyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group. R ₄ represents hydrogen. An atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxyl group, a sulfo group, a carboxyl group, an amino group, a sulfonamide group, a fluoro group, a chloro group, or a bromo group X represents a methylene chain, n is an integer of 0 to 20, A represents —CONH— or —NH—, and m is 0 or 1.)

According to our knowledge, an image-forming composition having excellent characteristics is provided by containing the alkali-insoluble polymer compound (A) and the acid-decomposable polymer compound (D) according to the present invention. It is thought that it is done.
That is, when the image forming composition is irradiated with infrared rays such as a semiconductor laser, the infrared absorbent can instantaneously generate heat of, for example, several hundred degrees by absorbing this light. The photoacid generator can be decomposed by the generated heat and the like to generate an acid. Due to the acid thus generated, the acid-decomposable polymer compound is decomposed at the silyl group (—O—Si—) moiety, and the alkali-insoluble polymer compound is decomposed at the protecting group (—O—P—) moiety. From a polymer having a phenolic hydroxyl group as a product [Polym-OH] and a decomposed silanol compound, while from an alkali-insoluble polymer compound, a polymer having a specific phenolic hydroxyl group and a protective group To produce the compound
There is a possibility that heat further contributes to the decomposition of the acid-decomposable polymer compound and the alkali-insoluble polymer compound. A polymer having a phenolic hydroxyl group generated by decomposition, a decomposed silanol compound, and a polymer having a specific phenolic hydroxyl group have high solubility in an alkaline developer or the like.
The image-forming composition of the present invention adopts a so-called chemical amplification type reaction mechanism, whereby the specific acid-decomposable polymer compound of the present invention has a structural site of -O-Si-, and the alkali-insoluble polymer compound has Since it has a structural site of a protecting group (—O—P—), it quickly solubilizes in an alkaline developer after acid decomposition. Therefore, even when irradiated with low laser energy, alkali solubility can be promoted uniformly throughout the photosensitive film, and the sensitivity of the photosensitive layer can be greatly increased.
On the other hand, the unexposed area exhibits high scratch resistance and is affected by an alkali developer due to the intermolecular interaction between the alkali-soluble resin and the acid-decomposable polymer compound when the photosensitive layer is applied to the support by dry coating. hard.
In addition, when the alkali-insoluble polymer compound of the present invention is added, specific logic-insoluble polymers are localized on the photosensitive film surface layer, although the clear logic is not known. The high hydrophobicity and alkali resistance of this polymer compound This is considered to be a photosensitive film layer comprising For this reason, even with a small point used in FM screening, the photosensitive layer itself has high hydrophobicity and alkali resistance, so that it is considered that development reproducibility is excellent.
Furthermore, the specific alkali-insoluble polymer compound is considered to remain unchanged even under high humidity and long-term storage at high temperatures because the resin has heat resistance and an alkali-soluble resin and acid-decomposable polymer compound interact with each other.

  According to the present invention, a positive image having high sensitivity to an infrared region such as a semiconductor laser, wide development latitude, scratch resistance, highlight reproducibility, high storage stability, and good post-development plate inspection properties. A positive photosensitive lithographic printing plate having the forming composition can be provided.

Hereinafter, the present invention will be described in detail. The image forming composition and the photosensitive lithographic printing plate according to the present invention are:
(A) an alkali-insoluble polymer compound represented by the above general formula (I);
(B) a photoacid generator;
(C) an infrared absorber;
(D) an acid-decomposable polymer compound represented by the general formula (II),
(E) It contains alkali-soluble resin.
Each component of the image forming composition of the present invention will be described in detail below.

The alkali-insoluble polymer compound (A) used in the present invention protects, for example, a polymer compound obtained by condensation reaction of an aromatic hydrocarbon having a phenolic hydroxyl group and N-methylolacrylamide under an acid catalyst. It can be easily synthesized by being protected with a group. Commercial products can also be used. Although not particularly limited, in the following formula (I), R ₁ and R ₂ are each independently hydrogen or a C _{1 to} C ₁₂ alkyl group, preferably a C _{1 to} C ₄ alkyl group. It is a group. Specifically, examples of R ₁ and R ₂ include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. The weight average molecular weight of the alkali-insoluble polymer compound is preferably 1000 or more, more preferably 1500 to 100,000.

(In the above formula, R ₁ and R ₂ each independently represent hydrogen or a C _{1 to} C ₁₂ alkyl group. P is a phenolic hydroxyl group in the above general formula (I) that can be dissociated by the action of an acid. Meaning a protective group.)

  As a preferred protecting group P, general protecting groups described in vinylphenol basics and applications (edited by Research Institute, Maruzen Petrochemical Co., Ltd.) can be used. Examples thereof include a tert-butoxycarbonyl group, a tetrahydropyranyl group, an ethoxyethyl group, a methyl group, an ethyl group, a butyl group, and an acetyl group.

  As a method for introducing these protecting groups P, for example, a polymer having an N-substituted acrylamide unit as a precursor is dissolved in a solvent, and a compound corresponding to the protecting group P, for example, di-tert-butyl dicarbonate, 3,4-dihydro-2H-pyran, ethyl vinyl ether, acetic anhydride and the like are added, and the mixture is allowed to react at room temperature to 150 ° C. for 30 minutes to 20 hours, followed by washing with water and drying. Alternatively, N-substituted acrylamide may be reacted with a compound corresponding to a protecting group, and the resulting reaction product may be polymerized.

  In the present invention, the amount of the alkali-insoluble polymer compound added is preferably 0.1 to 20% by weight, more preferably the lower limit is 0.2% by weight, and the more preferable upper limit is the total solid content of the image forming composition. 10% by weight. When the addition amount is less than 0.1% by weight, the alkali resistance tends to deteriorate, and when it exceeds 20% by weight, the alkali developability tends to decrease.

The photoacid generator which is the component (B) used in the present invention is a compound capable of generating an acid when the composition of the present invention is irradiated with near infrared or infrared light, and as a photoacid generator Various known compounds used and mixtures thereof can be used. For example, BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , SiF ₆ ²⁻ , ClO ₄ ⁻ salts of diazonium, phosphonium, sulfonium, and iodonium are preferable as the photoacid generator.

  Moreover, an organic halogen compound can be used as another photoacid generator. Organohalogen compounds are preferred in terms of sensitivity in image formation by near-infrared and infrared exposure and storage stability of the image-forming composition. As the organic halogen compound, triazines having a halogen-substituted alkyl group and oxadiazoles having a halogen-substituted alkyl group are preferable, and s-triazines having a halogen-substituted alkyl group are particularly preferable. Specifically, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine and the like.

  In the present invention, the addition amount of the photoacid generator is preferably 0.1 to 20% by weight, more preferably the lower limit is 0.2% by weight, and the more preferable upper limit is the total solid content of the image forming composition. 10% by weight. When the addition amount is less than 0.1% by weight, the sensitivity tends to deteriorate, and when it exceeds 20% by weight, it is difficult to dissolve in the solvent that dissolves the image forming composition.

In the present invention, the infrared absorber as component (C) is a photothermal conversion function that generates heat by irradiation with near infrared or infrared light (preferably light having a wavelength of 700 nm to 2500 nm, more preferably light having a wavelength of 700 nm to 1300 nm). It is a substance having The infrared absorber is used to quickly decompose the photoacid generator and easily generate an acid by the generated heat. As the infrared absorbent used in the present invention, an infrared absorbing dye having absorption at a wavelength of 700 nm or more, carbon black, magnetic powder, and the like can be used. A particularly preferable infrared absorber is an infrared absorbing dye having an absorption peak at a wavelength of 700 nm to 850 nm and having a peak molar absorption coefficient ε of 10 ⁵ or more.

  As the infrared absorbing dyes, cyanine dyes, squalium dyes, croconium dyes, azurenium dyes, phthalocyanine dyes, naphthalocyanine dyes, polymethine dyes, naphthoquinone dyes, thiopyrylium dyes, dithiol metal complex dyes, Anthraquinone dyes, indoaniline metal complex dyes, intermolecular CT dyes and the like are preferable.

  These dyes can be synthesized by a known method. Moreover, the following commercial items can also be used.

Nippon Kayaku Co., Ltd .: IR750 (anthraquinone), IR002, IR003 (aluminum), IR820 (polymethine), IRG022, IRG033 (diimmonium), CY-2, CY-4, CY-9, CY-10, CY-20
In addition, the above dyes are also commercially available from companies such as Honeywell, Akzo Noble, Nippon Photosensitive Dye, Sumitomo Chemical Co., Ltd. and Showa Denko. Hereinafter, specific examples of the infrared absorber preferably used in the present invention will be given, but the present invention is not limited thereto.

  In the present invention, the amount of the infrared absorber added is preferably 0.5 to 10% by weight, more preferably 0.6% by weight, and more preferably 7% by weight based on the total solid content of the image forming composition. %. When the addition amount is less than 0.5% by weight, the sensitivity tends to be slow, and when it exceeds 7% by weight, the developability of the exposed area tends to be lowered.

  The acid-decomposable polymer compound (D) used in the present invention can be synthesized by, for example, an addition reaction between a resin polymer [Polym-OH] having a phenolic hydroxyl group and a specific silane coupling agent. . This reaction is preferably carried out under the following conditions. That is, as a solvent, hexane, cyclohexane, benzene and the like are preferable. The amount of the solvent is preferably 10 to 200 g per 1 g of the resin polymer. Moreover, the amount of the specific silane coupling agent is preferably 0.5 to 100 mol per mol of the hydroxyl group of the resin polymer. Moreover, 50-150 degreeC of reaction temperature is preferable. The acid-decomposable polymer compound thus obtained can be purified by, for example, fractionating a solvent. The weight average molecular weight of the acid-decomposable polymer compound is preferably 1000 or more, and more preferably in the range of 1500 to 300,000.

  The specific silane coupling agent can be synthesized by various known synthesis methods. Commercial products can also be used. For example, phenethyltrimethoxysilane, phenyldiethoxysilane, N-phenylaminomethyltriethoxysilane, phenyldimethylethoxysilane, (p-methylphenethyl), which can be purchased from Toray Dow Corning, Tokyo Kasei, and Shin-Etsu Chemical Co., Ltd. Methyldichlorosilane, 3- (p-methoxyphenyl) propylmethyldichlorosilane, di (p-tolyl) dimethoxysilane diphenylmethylethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3- (p-methoxy) Phenyl) propylmethyldichlorosilane, 3- (p-methoxyphenyl) propyltrichlorosilane, pentafluorophenylpropyltrimethoxysilane, pentafluorophenylpropyltrichlorosilane, pentafluoro Phenylpropyl methyldichlorosilane, pentafluoro-phenylpropyl dimethylchlorosilane and the like are preferable.

  The resin polymer [Polym-OH] having a phenolic hydroxyl group can be synthesized by various known synthesis methods. In that case, the position of the hydroxyl group is not particularly limited, and may be directly bonded to the aromatic ring of the main chain or may be a part of the side chain. Moreover, you may use a commercial item. The weight average molecular weight of the resin polymer is preferably 1000 or more, and more preferably 1500 to 300,000. Specifically, the resin polymer having a phenolic hydroxyl group is a cresol formaldehyde resin {for example, m-cresol formaldehyde resin, p-cresol formaldehyde resin, o-cresol formaldehyde resin, m-cresol formaldehyde resin and p-cresol formaldehyde resin. Mixing, phenol / cresol (as cresol, for example, any of m-cresol, p-cresol, o-cresol, m-cresol and p-cresol, or m-cresol and o-cresol may be mixed) Formaldehyde resin, etc.}, resol type phenol resins, pyrogallol / acetone resin, polyvinyl phenol, vinyl phenol / styrene copolymer, vinyl phenol / methyl methacrylate Polymer, t-butyl substituted polyvinylphenol resin, copolymer with N- (4-hydroxyphenyl) maleimide, copolymer with N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacryl A copolymer with an amide is preferred.

  The introduction rate of the specific silane coupling agent into the resin polymer is preferably 5 to 100%. If the introduction ratio is less than 5%, the difference in solubility (contrast) in the developer between the exposed area and the unexposed area may deteriorate. The introduction rate refers to the ratio of the hydroxyl group of the resin polymer to which the specific silane coupling agent is bonded. Hereinafter, although the specific example of the acid-decomposable polymer compound preferably used for this invention is given, this invention is not restrict | limited to these.

  The acid-decomposable polymer compound used in the present invention may be used alone or in combination. The amount of these acid-decomposable polymer compounds added is preferably 1 to 60% by weight, more preferably 1.5% by weight and more preferably 60% by weight based on the total solid content of the image-forming composition. It is. When the addition amount is less than 1% by weight, the difference in solubility (contrast) in the developer between the exposed part and the unexposed part may deteriorate, and when it exceeds 60% by weight, the sensitivity may deteriorate.

  In the present invention, the alkali-soluble resin as the component (E) is particularly preferably a polymer alkali-soluble novolak resin having a residual monomer during resin synthesis of 10% by weight or less and a softening point of 120 ° C. to 190 ° C. By reducing the residual monomer to 10% by weight or less, it becomes difficult to be attacked by the solvent contained in the plate cleaner or the like, and furthermore, by adopting a high heat-resistant novolak resin having a softening point in the range of 120 ° C to 190 ° C, It is presumed that the acid-decomposable polymer compound, which is the component (D) of the image forming composition of the present invention, easily interacts with the molecule at the time of coating the photosensitive layer, the resistance to alkaline developer is improved and the development latitude is widened. A preferable lower limit of the residual monomer is 0% by weight. When the softening point exceeds 190 ° C., it becomes difficult to dissolve in a solvent that dissolves the image forming composition. The softening point is a value that can be generally measured by a solution viscosity test method (capillary viscometer method).

  Examples of the polymer alkali-soluble novolak resin include phenol / formaldehyde resin, cresol / novolak resin, cresol / trioxane resin, cresol / formaldehyde resin, phenol / cresol / formaldehyde copolycondensation resin (see JP-A-55-57841). ), P-substituted phenol and phenol, or a copolycondensation resin of cresol and formaldehyde (see JP-A-55-127553).

These alkali-soluble resins can be synthesized by a known method. Moreover, the following commercial items can also be used.
CKM-2400 (monomer content 1% or less, softening point 150 ° C.) (made by Showa Polymer Co., Ltd.), CKM-2432 (monomer content 0%, softening point 130 ° C.) (made by Showa Polymer Co., Ltd.), BRM-565 (Monomer content 5% or less, softening point 130 ° C.) (manufactured by Showa Polymer Co., Ltd.), CRM-957A (monomer content 7% or less, softening point 140 ° C.) (manufactured by Showa Polymer Co., Ltd.), REZ-958 (monomer Content 1% or less, softening point 160 ° C. (manufactured by Showa Polymer Co., Ltd.), RT-95 (monomer content 5% or less, softening point 170 ° C.) (manufactured by Gifu Shellac Co., Ltd.), others, Gunei Chemical Industry Co., Ltd. It is also sold by companies such as Sumitomo Bakelite and Hitachi Chemical.

  The polymer alkali-soluble novolak resins used in the present invention may be used alone or in combination of two or more. The addition amount is preferably 20 to 99% by weight, more preferably 25 to 98% by weight, based on the total solid content of the image forming composition. When the addition amount is less than 20% by weight, image formation may be deteriorated, and when it exceeds 99% by weight, chemical resistance may be deteriorated.

  Further, the photosensitive layer used in the present invention may contain a novolak resin other than those described above. The addition amount is preferably 0 to 20% by weight, more preferably 10% by weight, based on the total solid content of the image forming composition. When the addition amount exceeds 20% by weight, printing durability and chemical resistance are liable to deteriorate.

  In the photosensitive layer used in the present invention, it is more preferable in terms of development latitude to mix a novolak resin and the following alkali-soluble acrylic copolymer. The addition amount of the acrylic copolymer is preferably 5 to 40% by weight with respect to the novolak resin, the more preferable lower limit is 6% by weight, and the more preferable upper limit is 35% by weight. When the addition amount is less than 5% by weight, chemical resistance and printing durability may be deteriorated, and when it exceeds 50% by weight, image formability may be deteriorated.

As such an alkali-soluble acrylic copolymer resin, a copolymer of a monomer selected from the following (1) to (10), which is preferably an alkali-soluble acrylic copolymer having a phenolic hydroxyl group.
(1) A monomer having a phenolic hydroxyl group. For example, N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacrylamide, N- (4-hydroxyphenyl) maleimide, p-isopropenylphenol, o-hydroxystyrene, m-hydroxystyrene, p -Hydroxystyrene, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p-hydroxyphenyl methacrylate.
(2) A monomer having a sulfonamide group. For example, m-aminosulfonylphenyl methacrylate, N- (4-aminosulfonylphenyl) methacrylamide, N- (4-aminosulfonylphenyl) acrylamide.
(3) A monomer having an active imide group. For example, N- (4-toluenesulfonyl) methacrylamide and N- (4-toluenesulfonyl) acrylamide.
(4) A monomer having an aliphatic hydroxyl group. For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-phenoxypropyl methacrylate.
(5) α, β-unsaturated carboxylic acid. For example, acrylic acid, methacrylic acid, and maleic anhydride.
(6) A monomer having an allyl group. For example, allyl methacrylate and N-allyl methacrylamide.
(7) Alkyl acrylates or alkyl methacrylates. For example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, They are butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, and glycidyl methacrylate.
(8) Acrylamides or methacrylamides. For example, acrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl acrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamides, or methacrylamide, N-methylol methacrylamide, N -Ethyl methacrylamide, N-hexyl methacrylamide, N-cyclohexyl methacrylamide, N-hydroxyethyl methacrylamide, N-phenyl methacrylamide.
(9) Styrenes. For example, styrene, α-methylstyrene, chloromethylstyrene and the like.
(10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.

  Furthermore, the acrylic copolymer may be a copolymer obtained by further copolymerizing a monomer other than those that can be copolymerized with the monomer. In addition, the acrylic copolymer may be obtained by modifying an acrylic copolymer obtained by copolymerization of the monomer with, for example, glycidyl methacrylate.

  For the purpose of coloring the image-forming composition of the present invention, by adding a leuco dye and an oil-soluble dye and / or a basic dye, the image visibility can be improved without deteriorating the sensitivity (image inspection). Can be realized. Details are unknown, but adding a necessary amount of leuco pigment or oil-soluble dye and / or basic dye alone with good visibility produces a high dissolution inhibitory effect, which causes a significant decrease in sensitivity and storage stability. . Furthermore, when a necessary amount of leuco dye is added alone to reproduce sufficient image visibility, the situation becomes the same as when an excess organic acid is added, as estimated from the structural formula of the compound. The chemical resistance and alkali resistance are greatly reduced. Therefore, there are few target coloring effects and image visibility effects, with only a very small addition amount. However, when a leuco dye and an oil-soluble dye and / or a basic dye are added to the image-forming composition of the present invention, the acid-decomposable polymer as component (D) is shown although it exhibits a high dissolution inhibiting effect. Since a decomposed silanol compound having high alkali solubility is generated at the time of decomposition of the compound, it is possible to have high sensitivity and sufficient image visibility (image plate inspection) without lowering the sensitivity at the time of development.

  Examples of the leuco dye used in the present invention include 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide and 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl). -2-methylindol-3-yl) -4-azaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (4- Diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6,6′-tris (dimethyl-amino) spiro [fluorene-9,3′-phthalide], 3,3-bis (1-n-butyl-2) -Methyl-indol-3-yl) phthalide and the like are preferred.

  The amount of these leuco dyes added is preferably 0.05 to 20% by weight in the total solid content of the image forming composition. A more preferred lower limit is 0.1% by weight, a more preferred upper limit is 15% by weight, and a still more preferred upper limit is 10% by weight.

  Examples of the oil-soluble dye and / or basic dye used in the present invention include crystal violet, malachite green, Victoria blue, methylene blue, ethyl violet, rhodamine B, Victoria pure blue BOH (manufactured by Hodogaya Chemical Co., Ltd.), and oil blue. 613 (made by Orient Chemical Industry Co., Ltd.), oil green, etc. are mentioned.

  The addition amount of these dyes is preferably 0.05 to 5.0% by weight with respect to the total solid content of the image forming composition, more preferably 0.1% by weight and more preferably 4%. 0.0% by weight. If it is less than 0.1% by weight, the image forming layer may be insufficiently colored and the image may be difficult to see. If it exceeds 5.0% by weight, the dye tends to remain in the non-image area after development. Absent.

  Furthermore, an oleophilic resin can be added to the photosensitive layer formed from the image forming composition of the present invention in order to improve the sensitivity of the photosensitive layer.

  Examples of the lipophilic resin include condensates of phenols and aldehydes substituted with an alkyl group having 3 to 15 carbon atoms, or t-butylphenol formaldehyde as described in JP-A-50-125806. Resin etc. can be used.

  In the image forming composition of the present invention, if necessary, a cyclic acid anhydride, a phenol, and an organic acid can be used in combination for the purpose of improving sensitivity. As the cyclic acid anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, succinic anhydride, pyromellitic anhydride, and the like can be used.

  As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ′, 4 ′ '-Trihydroxytriphenylmethane, 4,4', 3 '', 4 ''-tetrahydroxy-3,5,3 ', 5'-tetramethyltriphenylmethane and the like are preferable.

  Examples of organic acids include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, Adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, etc. Can be mentioned.

  The proportion of the cyclic acid anhydride, phenols, and organic acids in the total solid content of the image forming composition is preferably 0.05 to 20% by weight, and a more preferable lower limit is 0.1% by weight, and more preferably. The upper limit is 15% by weight, and a more preferable upper limit is 10% by weight.

  Further, the image forming composition of the present invention has a nonionic surfactant as described in JP-A-62-251740 and JP-A-3-208514 in order to broaden the processing stability against development conditions. , Amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149 can be added. Preferable examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Preferred examples of amphoteric surfactants include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K”: manufactured by Daiichi Kogyo Co., Ltd.) and the like. The proportion of the nonionic surfactant and the amphoteric surfactant in the total solid content of the image forming material is preferably 0.05 to 15% by weight, and a more preferable lower limit is 0.1% by weight.

  The photosensitive lithographic printing plate according to the present invention can be produced by dissolving each component of the image forming composition in an appropriate solvent, applying the solution on a support and drying. At this time, the concentration of the image forming material is preferably 1 to 50% by weight, a more preferable lower limit is 5% by weight, and a more preferable upper limit is 30% by weight.

  As the solvent, methanol, ethanol, propanol, methylene chloride, ethyl acetate, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl cellosolve, methyl cellosolve acetate, dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, acetone , Cyclohexanone, trichloroethylene, methyl ethyl ketone and the like are preferable. These solvents can be used alone or in admixture of two or more.

Application of the solvent containing the image forming composition to the support can be performed by a conventionally known method such as spin coating, extrusion coating, wire bar coating, roll coating, air knife coating, dip coating, and curtain coating. . Although the quantity to apply | coat changes with uses, 0.5-5.0 g / m < ² > is preferable as solid content.

  The drying temperature is preferably 30 to 180 ° C, more preferably 50 to 150 ° C. The drying treatment is preferably performed for 10 seconds to 2 hours. Moreover, it is preferable to age the lithographic printing plate obtained by applying the photosensitive layer and drying it. Aging can be further performed by maintaining the temperature at 30 to 100 ° C. for 1 to 168 hours, preferably 3 to 96 hours. As an aging effect, a stronger bond is formed between the specific acid-decomposable polymer compound of the present invention and the alkali-soluble resin, and a tough photosensitive layer is formed. As a result, scratch resistance and development latitude are improved. Leads to.

  Examples of the support include a metal plate such as aluminum, zinc, copper, or steel, a metal plate plated or vapor-deposited with chromium, zinc, copper, nickel, aluminum, or iron, paper, plastic film, or glass. Examples thereof include a plate, paper coated with a resin, and a plastic film subjected to a hydrophilic treatment.

  When the present invention is applied to a photosensitive lithographic printing plate, as the support, a brush or ball-polished aluminum plate, brush-polished aluminum plate, anodized, electropolished, and then anodized An aluminum plate or an aluminum plate subjected to a combination of these is particularly preferable.

  The aluminum plate thus pretreated is further subjected to, for example, chemical conversion treatment with an alkali silicate, sodium phosphate, sodium fluoride, zirconium fluoride, alkyl titanate, trihydroxybenzoic acid or the like alone or in a mixed solution. , Sealing in a hot aqueous solution or steam bath, coating treatment with an aqueous solution of strontium acetate, zinc acetate, magnesium acetate or calcium benzoate, polyvinylpyrrolidone, polyaminesulfonic acid, polyvinylphosphonic acid, poly A surface or back surface coating treatment with acrylic acid, polymethacrylic acid or the like can also be performed as a post-treatment.

  Furthermore, as the above-mentioned support, an aluminum support subjected to the surface treatment described in JP-A-10-297130 can be used.

  As the laser light source for irradiating the image forming composition of the present invention with actinic rays, solid or semiconductor laser light having an oscillation wavelength in the near infrared to infrared region is preferable.

  As the developer used for developing the image forming composition of the present invention, an aqueous alkaline developer is suitable. As an aqueous alkaline developer, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, dibasic sodium phosphate, tribasic sodium phosphate, etc. An aqueous solution of an alkali metal salt of

  A surfactant can be further added to the alkaline aqueous solution. As the surfactant, an anionic surfactant or an amphoteric surfactant can be used.

  Examples of the ionic surfactant include sulfates of alcohols having 8 to 22 carbon atoms (for example, polyoxyethylene alkyl sulfate soda salt), alkyl aryl sulfonates (for example, sodium dodecylbenzenesulfonate, polyoxyethylene dodecylphenyl sulfate). Soda salt, alkyl naphthalene sulfonic acid soda, naphthalene sulfone soda, formalin condensate of naphthalene sulfone soda), sodium dialkyl sulfonate, alkyl ether phosphate, alkyl phosphate, and the like can be used. In addition, as the amphoteric surfactant, for example, alkylbetaine type and alkylimidazoline type surfactants are preferable. Furthermore, for example, water-soluble sulfites such as sodium sulfite, potassium sulfite, lithium sulfite, and magnesium sulfite can be added to the alkaline aqueous solution.

The present invention will be described more specifically with reference to the following examples. However, the present examples do not limit the present invention.
[Synthesis of acid-decomposable polymer compound PS-1]
As a resin polymer containing a phenolic hydroxyl group, Marcalinker CST70 (vinylphenol: styrene = 7: 3) (manufactured by Maruzen Petrochemical Co., Ltd.) (0.26 g) and phenethyltrimethoxysilane (0.34 g: (Theoretical introduction rate 100%) was mixed in hexane (10 ml), heated and stirred at 70 ° C. for 1 hour, and then hexane was fractionated to obtain an acid-decomposable polymer compound PS-1. Note that a new peak due to -Si-O- appeared in the IR spectrum. From this, it was confirmed that the desired reaction was performed. In this specification, the theoretical introduction rate of 100% means that the amount of the silane coupling agent is stoichiometrically equivalent to the hydroxyl group of the polymer.

[Synthesis of acid-decomposable polymer compound PS-2]
As a resin polymer containing a phenolic hydroxyl group, Marcalinker CST70 (vinylphenol: styrene = 7: 3) (manufactured by Maruzen Petrochemical Co., Ltd.) (0.26 g) and N-phenylaminopropyltrimethoxysilane (0.26 g) as a silane coupling agent ( 0.39 g: theoretical introduction rate 100%) was mixed in hexane (10 ml), and heated and stirred at 70 ° C. for 1 hour, and then hexane was fractionated to obtain an acid-decomposable polymer compound PS-2. It was. Note that a new peak due to -Si-O- appeared in the IR spectrum. From this, it was confirmed that the desired reaction was performed.

[Synthesis of acid-decomposable polymer compound PS-3]
As a resin polymer containing a phenolic hydroxyl group, Marcalinker CST70 (vinylphenol: styrene = 7: 3) (manufactured by Maruzen Petrochemical Co., Ltd.) (0.26 g) and phenyldimethylethoxysilane (0.27 g : (Theoretical introduction rate: 100%) was mixed in hexane (10 ml), heated and stirred at 100 ° C. for 1 hour, and then hexane was fractionated to obtain an acid-decomposable polymer compound PS-2. Note that a new peak due to -Si-O- appeared in the IR spectrum. From this, it was confirmed that the desired reaction was performed.

[Synthesis of acid-decomposable polymer compound PS-4]
As a resin polymer containing a phenolic hydroxyl group, Marcalinker CST70 (vinylphenol: styrene = 7: 3) (manufactured by Maruzen Petrochemical Co., Ltd.) (0.26 g) and p-aminophenyltrimethoxysilane (0 .32 g: theoretical introduction rate 100%) was mixed in hexane (10 ml), heated and stirred at 70 ° C. for 1 hour, and then hexane was fractionated to obtain an acid-decomposable polymer compound PS-4. . Note that a new peak due to -Si-O- appeared in the IR spectrum. From this, it was confirmed that the desired reaction was performed.

[Synthesis of Comparative Acid Decomposable Polymer Compound (1)]
As a resin polymer containing a phenolic hydroxyl group, Marcalinker CST70 (vinylphenol: styrene = 7: 3) (manufactured by Maruzen Petrochemical Co., Ltd.) (0.215 g) and 2-nitrobenzyl-6- (tri Methoxysilyl) hexyl ether (0.45 g: theoretical introduction rate: 100%) was mixed in hexane (10 ml), heated and stirred at 70 ° C. for 1 hour, and then hexane was fractionated to perform comparative acid decomposition. Functional polymer compound (1) was obtained. Note that a new peak due to -Si-O- appeared in the IR spectrum. From this, it was confirmed that the desired reaction was performed.

[Precursor synthesis of alkali-insoluble polymer compound (1)]
[Synthesis 1-1]
In a separable flask equipped with a thermometer, a stirrer and a reflux condenser, 100 g of 2,6-xylenol, 150 g of ion exchange water, 0.05 g of N-nitrosophenylhydroxylamine aluminum salt, 107.6 g of N-methylolacrylamide, oxalic acid 4.0 g was charged and reacted at 60 ° C. for 1 hour, and then 2.0 g of oxalic acid was further added and reacted at 65 ° C. for 5 hours. After washing with water, filtration, and drying, 153.8 g of white powder was obtained. As a result of measuring IR before and after the reaction, it was confirmed that the product had a characteristic absorption of 1700 cm ⁻¹ derived from an amide bond and a characteristic absorption of 980 cm ⁻¹ derived from an acryloyl group.
[Synthesis 1-2]
Next, in a separable flask equipped with a thermometer, a stirrer and a reflux condenser, 100 g of white powder obtained in Synthesis 1, 100 g of N, N-dimethylacetamide, 10 g of perbutyl Z (manufactured by NOF Corporation) as a polymerization initiator. And reacted at 140 ° C. for 4 hours. After washing with water, washing with acetone, and drying, 30.6 g of a brown powder (precursor) polymer was obtained. The weight average molecular weight in gel permeation chromatograph [GPC] using polystyrene as a standard was 7350. As a result of measuring IR before and after the reaction, it was confirmed that the characteristic absorption at 980 cm ⁻¹ derived from the acryloyl group disappeared in the polymer.

[Synthesis of Alkali Insoluble Polymer Compound (1)]
In a separable flask equipped with a thermometer, a stirrer, and a reflux condenser, 15.0 g of the brown powder polymer obtained in [Synthesis 1-2] and 150 ml of tetrahydrofuran were charged and dissolved. After dissolution, 16 g of di-tert-butyl dicarbonate and 0.02 g of N, N-dimethylaminopyridine were added and reacted at 50 ° C. for 6 hours. After washing with water and drying, 22.1 g of a light brown powder polymer (alkali-insoluble polymer compound (1)), which was the target product, was obtained. The weight average molecular weight in GPC using polystyrene as a standard was 10900.

[Synthesis of Comparative Alkali Insoluble Polymer Compound (1)]
0.4 g of 4-dimethylaminopyridine was added to a solution of poly (4-hydroxystyrene) (Mw = 4500) in 800 ml of propylene glycol monomethyl ether. Next, 94 g of di-tert-butyl dicarbonate was added dropwise over 30 minutes as a solution in 100 ml of propylene glycol monomethyl ether while stirring was continued. After completion of the dropwise addition, the reaction was completed by further stirring for 1 hour at room temperature. The reaction solution was poured into water little by little while stirring vigorously, and the polymer was filtered off and dried at 50 ° C. in vacuum to obtain a polymer (comparative alkali-insoluble polymer compound (1)). .

[Synthesis of alkali-soluble acrylic copolymer (1)]
In a 500 ml four-necked flask equipped with a stirrer and a condenser, 18.7 g of reagent A [N- (p-hydroxyphenyl) maleimide, 17.2 g of acrylonitrile, 5 g of methyl methacrylate, 6.5 g of 2-hydroxyethyl methacrylate And dimethylacetamide (108 g) were added, and the atmosphere was replaced with nitrogen for about 20 minutes. Next, after heating to 73 ° C. in an oil bath, reagent B [2,2′-azobis (2-methylbutyronitrile) 0.25 g] was added and stirred for 2 hours. This reaction mixture was further mixed with reagents C [N- (p-hydroxyphenyl) maleimide 18.7 g, acrylonitrile 17.2 g, methyl methacrylate 5 g, 2-hydroxyethyl methacrylate 6.5 g and dimethylacetamide 108 g and 2,2 ′. -Azobis (2-methylbutyronitrile) 0.25 g] was dropped by a dropping funnel over 2 hours. After completion of dropping, the mixture was further stirred at 73 ° C. for about 2 hours to obtain an alkali-soluble acrylic copolymer (1) having a concentration of 30 wt%.

A support was prepared as follows. After 0.24 mm thick aluminum (material 1050) was alkali degreased, the surface was polished with a nylon brush while applying a water suspension of permiston and washed thoroughly with water. Next, a 15 wt% sodium hydroxide aqueous solution was poured for 5 seconds at 70 ° C., the surface was etched by 3 g / m ² , further washed with water, and then electrolytically roughened at 200 coulomb / dm ² in a 1N hydrochloric acid bath. Processed. Subsequently, after washing with water, the surface was etched again with a 15% by weight aqueous sodium hydroxide solution, washed with water, then immersed in a 20% by weight aqueous nitric acid solution and desmutted. Next, anodization was performed in a 15% by weight sulfuric acid aqueous solution to form a 2.0 g / m ² oxide film. After washing with water, after-treatment with a 2% by weight potassium fluoride solution at 50 ° C., washing with water , Dried.

[Example 1]
On the obtained aluminum support, the following photosensitive solution 1 was applied using a 0.2 mm bar so that the film thickness after drying was 2.0 g / m ^2, and dried at 100 ° C. for 7 minutes for lithographic printing. Got a version.

(Photosensitive solution 1)
(A) Specific alkali-insoluble polymer compound (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: the following cyanine compound (IR-2) (0.1 g)
(D) Acid-decomposable polymer compound PS-1: (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolac resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g)
: Alkali-soluble acrylic copolymer (1) (1.0 g)
Dye: Oil Blue 613 (Orient Chemical Co., Ltd.) (0.05 g)
Leuco dye: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (0.05 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

シアニン化合物（ＩＲ−２）

Cyanine compound (IR-2)

[Example 2] On the same support as in Example 1, the following photosensitive solution 2 was applied using a 0.2 mm bar so that the film thickness after drying was 2.0 g / m ² , and 7 at 100 ° C. A lithographic printing plate was obtained by drying for a minute.

(Photosensitive solution 2)
(A) Specific alkali-insoluble polymer compound (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: the above cyanine compound (0.1 g)
(D) Acid-decomposable polymer compound PS-2: (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolak resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g): Alkali-soluble acrylic copolymer (1) (1.0 g)
Dye: Oil Blue 613 (Orient Chemical Co., Ltd.) (0.05 g)
Leuco dye: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (0.05 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

[Example 3]
The following photosensitive solution 3 was applied onto the same support as in Example 1 using a 0.2 mm bar so that the film thickness after drying was 2.0 g / m ^2, and dried at 100 ° C. for 7 minutes to be a lithographic plate A printed version was obtained.

(Photosensitive solution 3)
(A) Specific alkali-insoluble polymer compound (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: the cyanine compound (IR-2) (0.1 g)
(D) Acid-decomposable polymer compound PS-3: (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolak resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g): Alkali-soluble acrylic copolymer (1) (1.0 g)
Dye: Oil Blue 613 (Orient Chemical Co., Ltd.) (0.05 g)
Leuco dye: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (0.05 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

[Example 4]
The following photosensitive solution 4 was applied on the same support as in Example 1 using a 0.2 mm bar so that the film thickness after drying was 2.0 g / m ^2, and dried at 100 ° C. for 7 minutes to be a lithographic plate A printed version was obtained.

(Photosensitive solution 4)
(A) Specific alkali-insoluble polymer compound (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: the cyanine compound (IR-2) (0.1 g)
(D) Acid-decomposable polymer compound PS-4: (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolak resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g): Alkali-soluble acrylic copolymer (1) (1.0 g)
Dye: Oil Blue 613 (Orient Chemical Co., Ltd.) (0.05 g)
Leuco dye: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (0.05 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

[Comparative Example 1]
The following image forming composition was applied on the same support as in Example 1 and dried in the same manner as in Example 1 to obtain a lithographic printing plate.

(Photosensitive solution 5)
(A) Alkali insoluble polymer compound for comparison (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: Cyanine compound (IR-2) (0.1 g)
(D) Acid-decomposable polymer compound PS-1: (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolac resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g)
: Alkali-soluble acrylic copolymer (1) (1.0 g)
Dye: Oil Blue 613 (Orient Chemical Co., Ltd.) (0.05 g)
Leuco dye: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (0.05 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

[Comparative Example 2]
The following image forming composition was applied onto the same support as in Example 1 and dried in the same manner as in Example 1 to obtain a lithographic printing plate.

(Photosensitive solution 6)
(A) Specific alkali-insoluble polymer compound (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: Cyanine compound (IR-2) (0.1 g)
(D) Acid-decomposable polymer compound for comparison (1): (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolac resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g)
: Alkali-soluble acrylic copolymer (1) (1.0 g)
Dye: Oil Blue 613 (Orient Chemical Co., Ltd.) (0.05 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

[Comparative Example 3]
The following image forming composition was applied onto the same support as in Example 1 and dried in the same manner as in Example 1 to obtain a lithographic printing plate.

(Photosensitive solution 7)
(A) Alkali insoluble polymer compound for comparison (1): (0.03 g)
(B) Photoacid generator: 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine (0.021 g)
(C) Infrared absorber: the cyanine compound (IR-2) (0.1 g)
(D) Acid-decomposable polymer compound PS-4: (0.215 g)
(E) Alkali-soluble resin: specific novolak resin (RT-95) (monomer content 5% or less, softening point 170 ° C. (manufactured by Gifu Shellac Co., Ltd.)) (2.8 g)
: Novolac resin (PSF-2807) (manufactured by Gunei Chemical Co., Ltd.) (0.25 g)
: Alkali-soluble acrylic copolymer (1) (1.0 g)
Leuco dye: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (0.2 g)
Solvent: propylene glycol monomethyl ether / methyl cellosolve (20 ml / 5 ml)

  Next, each lithographic printing plate thus obtained was imaged with 200 lines and 1 to 99% halftone dot lines at various exposure energies using a semiconductor laser with a wavelength of 830 nm (manufactured by Creo: Trendsetter 800QTM). The film was exposed to light, and then developed with a 1: 7 diluted alkaline developer (TD-4) manufactured by Okamoto Chemical Co., Ltd. for 12 seconds at an automatic developing machine PK-910II at a liquid temperature of 30 ° C.

Next, the following evaluations were performed, and the results are shown in Table 1.
(1) As the evaluation of sensitivity, when the non-image area (exposed area) of the printing plate developed by the automatic processor was inked, the determination was made based on the minimum exposure amount until the non-image area was not smudged.
(2) As an evaluation of the development latitude, each lithographic printing plate is exposed at the minimum exposure determined in (1) above, and then immersed in the alkaline developer, and the image area (unexposed area) disappears. The time until was measured.
(3) As an evaluation of highlight reproducibility, each lithographic printing plate was subjected to FM with an exposure energy 1.3 times the minimum exposure amount of each lithographic printing plate determined in (1) above using the semiconductor laser. A screening (Staccato 20) image was irradiated and developed under the same conditions by the automatic processor.
<Evaluation criteria>
◎: 1% halftone dot is reproduced.
Δ: 1% halftone dot edge is missing.
×: 1% halftone dot disappeared.
(4) For evaluation of scratch resistance, a slip sheet (Mitsubishi Paper Sales Co., Ltd. Mitsubishi NCR Super Upper Paper) is overlaid on the plate material, and the photosensitive layer is intentionally rubbed while being weighted with a 200 g weight. Thereafter, overdevelopment was performed in the developer at 30 ° C. for 20 seconds, and the scratch strength was evaluated based on the dissolution of the photosensitive layer.
<Evaluation criteria>
A: No change Δ: Gloss reduction of photosensitive layer x: Peeling of photosensitive layer (5) As an evaluation of storage stability, each lithographic printing plate is forcibly stored for 5 days in a constant temperature bath at 40 ° C. and 70% humidity. Thereafter, irradiation is performed using a semiconductor laser having a wavelength of 830 nm (manufactured by Creo: Trendsetter 800QTM) at the minimum exposure determined in (1) above, and the automatic processor PK-910II is used at a liquid temperature of 30 ° C. for 12 seconds. Developed.
<Evaluation criteria>
A: Development is possible with the same exposure as before forced storage, and the non-image area is not stained even when inked. Sensitivity decline does not occur.
X: When developing with the same exposure amount as before forced storage, development failure occurs and the image becomes dirty. Sensitivity is reduced.
(6) As an evaluation of plate inspection property (image visibility), each lithographic printing plate was irradiated with the minimum exposure amount obtained in (1) above, and the liquid temperature was 30 ° C. with the automatic processor PK-910II. After developing for 12 seconds, the difference in cyan density between the image area and the non-image area was measured with a ccDOT meter manufactured by SDG Corporation. At that time, the cyan density difference was ΔD, 0.9 or more was marked with ◎, and 0.8 or less was marked with ×.
<Evaluation criteria>
A: ΔD ≧ 0.9
×: ΔD ≦ 0.8

  As is apparent from Table 1, the lithographic printing plate according to the present invention has high sensitivity to the infrared region such as a semiconductor laser, large development latitude, highlight reproducibility, scratch resistance, storage stability, and plate inspection. It is a printing plate that is excellent in.

Claims (3)

(A) an alkali-insoluble polymer compound represented by the following general formula (I):
(B) a photoacid generator;
(C) an infrared absorber;
(D) an acid-decomposable polymer compound represented by the following general formula (II) that generates a resin polymer [Polym-OH] having a phenolic hydroxyl group and a decomposed silanol compound by the action of an acid;
(E) An image forming composition containing an alkali-soluble resin.

(In the above formula, R ₁ and R ₂ each independently represent hydrogen or a C ₁ -C ₁₂ alkyl group. P in the general formula (I) is capable of dissociating a phenolic hydroxyl group by the action of an acid. Means protecting group.)

(In the general formula (II), two R _{3 s} each independently represent an alkyl group, an alkoxy group, a hydroxyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group. R ₄ represents a hydrogen atom, An alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxyl group, a sulfo group, an amino group, a carboxyl group, a sulfonamide group, a fluoro group, a chloro group, or a bromo group, where X represents Represents a methylene chain, n is an integer of 0 to 20. A represents —CONH— or —NH—, and m is 0 or 1.)   The image forming composition according to claim 1, wherein the image forming composition further contains a leuco dye and an oil-soluble dye and / or a basic dye.   A lithographic printing plate precursor having a photosensitive layer comprising the image forming composition according to claim 1 on a support.