JP2006142720A - Aluminum support for lithographic printing plate and lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to markedly reduce the trouble of a lithographic printing plate for CTP, especially an image omission trouble. <P>SOLUTION: In the aluminum support for a lithographic printing plate subjected to an electrochemical roughening processing, the surface roughness before the roughening processing is treated so as to have a center-line mean roughness Ra of at least 0.10 μm and not more than 0.24 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aluminum support for a lithographic printing plate and a lithographic printing plate, and more particularly to a technique for preventing a missing image portion of a negative lithographic printing plate, which is a lithographic printing plate for CTP, so-called film loss failure.

  Conventionally, PS plates having a constitution in which an oleophilic photosensitive resin layer is provided on a hydrophilic support are widely used as lithographic printing plate precursors, and the plate making method is usually mask exposure via a lithographic film. After (surface exposure), the desired printing plate was obtained by dissolving and removing the non-image area.

  In recent years, digitization techniques that use a computer to electronically process, store, and output image information have become widespread. Various new image output methods corresponding to such digitization techniques have come into practical use. As a result, computer-to-plate (CTP) technology that scans highly directional light such as laser light according to digitized image information and directly produces printing plates without going through a lith film is anxious. Therefore, obtaining a planographic printing plate precursor adapted to this has become an important technical issue.

  As such a lithographic printing plate capable of scanning exposure, hydrophilicity is provided by subjecting a support composed of aluminum on both sides or one side to a roughening treatment by polishing such as brush grains or electrolytic grains. In the field of lithographic printing plates for CTP, electrochemical surface roughening treatment, for example, surface roughening treatment by electrolytic grains, is increasing. A lipophilic photosensitive resin layer (hereinafter also referred to as a photosensitive layer) containing a photosensitive compound capable of generating active species such as radicals and Bronsted acids by laser exposure is coated on a roughened support. Is done. Then, the lithographic printing plate precursor is laser-scanned based on digital information to generate active species, and the action causes physical or chemical changes to the photosensitive layer to insolubilize, followed by development processing to obtain a negative type. A lithographic printing plate can be obtained. In particular, a photopolymerization type photosensitive layer containing a photopolymerization initiator excellent in photosensitive speed on a hydrophilic support, an ethylenically unsaturated compound capable of addition polymerization, and a binder polymer soluble in an alkali developer, and necessary A lithographic printing plate provided with an oxygen-blocking protective layer according to the above is a printing plate having desirable printing performance from the advantages of excellent productivity, simple development processing, and good resolution and inking properties. It can be

  Conventionally, as the binder polymer constituting the photosensitive layer, methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer, crotonic acid copolymer, maleic acid copolymer, partially esterified maleic acid copolymer Organic polymer polymers that can be developed with alkali have been used. In order to accelerate the curing reaction of the photosensitive layer, a method of providing a protective layer containing a water-soluble polymer on the photosensitive layer is known.

In Patent Document 1, a resin having a specific unsaturated group is used as a photosensitive layer of a lithographic printing plate as a polymer compound that is insoluble in water and soluble in an alkaline aqueous solution. Thereby, it is excellent in printing durability and can suppress the ablation in the laser scanning at the time of recording.
Japanese Patent Laid-Open No. 2002-62648

  However, the conventional lithographic printing plate for CTP has a problem that a failure, in particular, a film dropout failure is liable to occur, and the in-plane variation of the halftone dot area is large.

  The present invention has been made in view of such circumstances, and a lithographic printing plate capable of remarkably reducing a failure of a lithographic printing plate for CTP, particularly a film dropout failure, and reducing in-plane variation in halftone dot area. It is an object to provide an aluminum support for CTP and a lithographic printing plate for CTP using the support.

  The present inventor has pursued the cause of the failure of the lithographic printing plate for CTP, particularly the cause of the film loss, and when producing an aluminum support by rolling an aluminum ingot, fine streaks that cannot be visually determined are in the rolling direction. It was found that failure, in particular, film breakage failure is likely to occur when the stripe irregularities are transferred to the photosensitive layer. In particular, in the case of an electrochemical surface roughening treatment that tends to increase in a lithographic printing plate for CTP, for example, surface roughening treatment using electrolytic grains, the streaks generated during rolling are not removed even after the surface roughening treatment. The knowledge that it is easy to remain is obtained. Furthermore, in the case where the photosensitive layer coated on the aluminum support contains a monomer component of 25% or more, or is a soft photosensitive layer such that the total Tg of the photosensitive layer is 50 ° C. or less, it is manufactured. It was found that streaks remaining on the aluminum support were easily transferred to the photosensitive layer due to the winding pressure when the strip-shaped lithographic printing plate precursor was wound with a winder. The present invention has been made based on such findings.

  In order to achieve the above object, claim 1 of the present invention is an aluminum support for a lithographic printing plate on which an electrochemical roughening treatment is performed, the surface roughness before the roughening treatment being the center. Provided is an aluminum support for a lithographic printing plate having a line average roughness Ra of from 0.10 μm to 0.24 μm.

  According to the aluminum support for a lithographic printing plate of claim 1, the surface roughness before the electrochemical surface roughening treatment is 0.10 μm or more and 0.24 μm or less in terms of the center line average roughness Ra. Therefore, if a lithographic printing plate for CTP is produced using the aluminum support of the present invention, the failure of the lithographic printing plate, particularly the occurrence of film loss failure, can be significantly reduced. In addition, according to the aluminum support of the present invention, there is also an effect that the in-plane variation of the dot area in the planographic printing plate can be reduced.

  The center line average roughness Ra of the aluminum support in the present invention is more preferably from 0.10 μm to 0.20 μm, particularly preferably from 0.15 μm to 0.20 μm.

  Incidentally, the lower limit of the surface roughness was set to 0.10 μm as the center line average roughness Ra because the original plate of the lithographic printing plate produced using this aluminum support was wound into a roll on a winder. This is because when Ra is less than 0.10 μm, it becomes too slippery and stable winding cannot be performed, and it is more preferably 0.15 μm or more.

  The aluminum support having such center line average roughness Ra is a method of mirror-finishing the surface of the rolling roller when rolling an aluminum ingot, or performing multi-stage rolling by reducing the pressure during rolling, or adjusting the rolling time. Can be achieved.

  Claim 2 of the present invention is an aluminum support for a lithographic printing plate on which an electrochemical surface roughening treatment is performed in order to achieve the above object, and has a maximum surface roughness before the surface roughening treatment. Provided is an aluminum support for a lithographic printing plate, having a roughness Rmax of 1.6 μm or less.

  According to the aluminum support for a lithographic printing plate of the present invention, since the surface roughness before the electrochemical surface roughening treatment is 1.6 μm or less at the maximum roughness Rmax, the aluminum support of the present invention If a lithographic printing plate for CTP is produced using the body, the failure of the lithographic printing plate, in particular, the occurrence of film loss failure can be significantly reduced. In addition, according to the aluminum support of the present invention, there is also an effect that the in-plane variation of the dot area in the planographic printing plate can be reduced.

  The maximum roughness Rmax of the aluminum support in the present invention is more preferably 1.3 μm or less.

  The surface roughness before the electrochemical roughening treatment is 0.10 μm or more and 0.24 μm or less in terms of the center line average roughness Ra, and 1.6 μm or less in terms of the maximum roughness Rmax. More preferably. The center line average roughness Ra is more preferably 0.10 μm or more and 0.20 μm or less, and the maximum roughness Rmax is further preferably 1.6 μm or less. The center line average roughness Ra is particularly preferably 0.15 μm or more and 0.20 μm or less, and the maximum roughness Rmax is particularly preferably 1.3 μm or less.

  According to a third aspect of the present invention, in order to achieve the above object, a photosensitive material comprising an infrared absorber, a polymerization initiator, a polymerization compound, and a binder polymer on the aluminum support for a lithographic printing plate according to the first or second aspect. A lithographic printing plate comprising a layer and a protective layer are provided.

  The photosensitive layer containing an infrared absorber, a polymerization initiator, a polymerization compound, and a binder polymer has a configuration of a photosensitive layer of a lithographic printing plate for CTP, and the photosensitive layer having such a configuration is formed on the aluminum support of claim 1 or 2. The lithographic printing plate obtained by applying the layer can remarkably reduce the occurrence of failure, particularly film failure, and can also reduce the in-plane variation of the halftone dot area.

  A fourth aspect of the present invention is characterized in that, in the third aspect, the photosensitive layer contains 25% by weight or more of a monomer component.

  In the case of a soft photosensitive layer containing a monomer component in an amount of 25% by weight or more in the photosensitive layer, the use of the aluminum support according to claim 1 or 2 may cause a lithographic printing plate failure, particularly a film loss failure. This is because it is effective for reduction. Further, in the case of a soft photosensitive layer in which the monomer component is contained in the photosensitive layer in an amount of 50% by weight or more, the aluminum support of claim 1 or 2 is further effective.

  A fifth aspect of the present invention is characterized in that, in the fourth aspect, the molecular weight of the monomer component is 1000 or less. This is because when the molecular weight of the monomer component is 1000 or less, the use of the aluminum support according to claim 1 or 2 reduces the occurrence of film loss failure of the lithographic printing plate and the in-plane variation of the dot area. Because it is effective.

  A sixth aspect is characterized in that, in any one of the second to fifth aspects, the total Tg of the photosensitive layer is 50 ° C. or less. This is because, in the case of a soft photosensitive layer such that the total Tg of the photosensitive layer is 50 ° C. or less, the use of the aluminum support according to claim 1 or 2 may cause failure of the lithographic printing plate, particularly film loss. This is because it is effective in reducing the occurrence of failures and in-plane variation in the halftone dot area. The total Tg is the glass transition temperature of the entire plurality of layers. When the total Tg of the photosensitive layer is 30 ° C. or less, the aluminum support of claim 1 or 2 is further effective.

  As described above, according to the present invention, it is possible to remarkably reduce the failure of the lithographic printing plate for CTP, particularly the film dropout failure, and to reduce the in-plane variation of the halftone dot area.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an aluminum support for a planographic printing plate and a planographic printing plate according to the present invention will be described in detail with reference to the accompanying drawings.

  The lithographic printing plate precursor according to the present invention comprises a photosensitive layer containing an infrared absorber, a polymerization initiator, a polymerizable compound, and a binder polymer on the aluminum support of the present invention described later, and a layer for protecting the photosensitive layer. And a protective layer. This lithographic printing plate precursor is typified by a negative lithographic printing plate precursor for performing exposure treatment at a wavelength of 750 nm to 1400 nm and then developing without substantially undergoing heat treatment and water washing treatment. It is configured as follows.

(Photosensitive layer)
The photosensitive layer of the lithographic printing plate precursor according to the present invention contains, as essential components, an infrared absorber, a polymerization initiator, a polymerizable compound (also referred to as an addition polymerizable compound), and a binder polymer, and if necessary. A polymerizable negative photosensitive layer containing a colorant and other optional components.

  Since the polymerizable negative photosensitive layer in the present invention is sensitive to infrared light, it can be exposed to an infrared laser useful for CTP. Such infrared absorbers are in an electronically excited state with high sensitivity to infrared laser irradiation (exposure), and electron transfer, energy transfer, heat generation (photothermal conversion function), etc. associated with the electron excited state coexist in the photosensitive layer. Acting on the polymerization initiator to cause a chemical change in the polymerization initiator to generate radicals.

  The radical generation mechanism is as follows: 1. Heat generated by the photothermal conversion function of the infrared absorber thermally decomposes a polymerization initiator (for example, sulfonium salt) described later to generate radicals. 2. Excited electrons generated by the infrared absorber move to a polymerization initiator (for example, an active halogen compound) to cause radicals. For example, radicals are generated by electron transfer from a polymerization initiator (for example, a borate compound) to an excited infrared absorber. Then, the polymerizable compound causes a polymerization reaction by the generated radical, and the exposed portion is cured to become an image portion.

  The lithographic printing plate precursor according to the invention is particularly suitable for plate making directly drawn with an infrared laser beam having a wavelength of 750 to 1400 nm because the photosensitive layer contains an infrared absorber, and the conventional lithographic printing plate precursor Compared to the above, high image forming properties can be exhibited.

  Below, each component which comprises the photosensitive layer of the lithographic printing plate precursor concerning this invention is demonstrated.

(Infrared absorber)
The photosensitive layer of the lithographic printing plate precursor according to the invention contains an infrared absorber for the purpose of developing an energy transfer function (electron transfer), a photothermal conversion function, and the like.

  Infrared absorbers are in an electronically excited state with high sensitivity to infrared laser irradiation (exposure), and the electron transfer, energy transfer, heat generation (photothermal conversion function), etc. related to the electron excited state act on the polymerization initiator described later. Thus, it is useful for generating a radical by causing a chemical change in the polymerization initiator with high sensitivity.

  The infrared absorbent used in the present invention is preferably a dye or pigment having an absorption maximum at a wavelength of 750 nm to 1400 nm.

  As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

  Examples of preferable dyes include cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, 58-181690, JP-A-58-194595, etc., methine dyes, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59- No. 73996, JP-A-60-52940, JP-A-60-63744 and the like, Naphthoquinone dyes described in JP-A-58-112792, etc., British Patent 434,875 And cyanine dyes.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferable, and particularly preferable examples include cyanine dyes. Specific examples of cyanine dyes that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969.

  Further, other particularly preferable examples include specific indolenine cyanine dyes described in Japanese Patent Application Nos. 2001-6326 and 2001-237840.

  However, those containing no halogen ion as the counter ion are particularly preferred.

  When these infrared absorbers are used in the photosensitive layer of the lithographic printing plate precursor according to the invention, they may be added to the same layer as other components, or may be added to another layer.

  From the viewpoint of uniformity in the photosensitive layer and durability of the photosensitive layer, these infrared absorbers are 0.01 to 50% by mass, preferably 0.1 to 10% by mass, based on the total solid content constituting the photosensitive layer. In the case of a dye, it is particularly preferably 0.5 to 10% by mass, and in the case of a pigment, it is particularly preferably 0.1 to 10% by mass.

(Polymerization initiator)
The polymerization initiator used in the present invention has a function of initiating and advancing the curing reaction of a polymerizable compound described later, and is a thermal decomposition type radical generator that decomposes by heat to generate radicals, and excitation of an infrared absorber. Electron transfer type radical generator that accepts electrons and generates radicals, or electron transfer type radical generator that generates electrons by transferring electrons to an excited infrared absorber, and so on to give radicals. Any compound may be used as long as it is generated. For example, onium salts, active halogen compounds, oxime ester compounds, borate compounds and the like can be mentioned. These may be used in combination. In the present invention, an onium salt is preferable, and a sulfonium salt is particularly preferable.

  Examples of the sulfonium salt polymerization initiator suitably used in the present invention include onium salts represented by the following chemical formula (see Chemical Formula 1).

In the chemical formulas described above, R ¹¹ , R ¹² and R ¹³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. (Z ¹¹ ) − represents a counter ion selected from the group consisting of halogen ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, carboxylate ion, and sulfonate ion, preferably perchloric acid Ions, hexafluorophosphate ions, carboxylate ions, and aryl sulfonate ions.

  In addition, specific aromatic sulfonium salts described in JP-A Nos. 2002-148790, 2002-148790, 2002-350207, and 2002-6482 are also preferably used.

  In the present invention, in addition to the sulfonium salt polymerization initiator, other polymerization initiators (other radical generators) can be used. Other radical generators include onium salts other than sulfonium salts, triazine compounds having a trihalomethyl group, and among them, onium salts are preferred because of their high sensitivity. Moreover, these polymerization initiators (radical generators) can be used in combination with the sulfonium salt polymerization initiator as an essential component.

  Other onium salts that can be suitably used in the present invention include iodonium salts and diazonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators.

  Examples of other onium salts in the present invention include those described in JP-A No. 2001-133696.

  The polymerization initiator (radical generator) used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the lithographic printing plate precursor can be handled under white light.

  The total content of the polymerization initiator in the present invention is 0.1 to 50% by mass, preferably 0. 0% by mass with respect to the total solid content constituting the photosensitive layer, from the viewpoint of sensitivity and generation of stains in the non-image area during printing. It is 5-30 mass%, Most preferably, it is 1-20 mass%.

(Polymerizable compound)
The polymerizable compound used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one, preferably two or more ethylenically unsaturated bonds. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, that is, dimers, trimers and oligomers, or mixtures thereof, and copolymers thereof.

  In the case of a soft photosensitive layer containing 25% by weight or more of such monomer components, the use of the aluminum support of the present invention described later is effective in reducing the occurrence of lithographic printing plate failures, particularly film loss failures. is there. In the case of a soft photosensitive layer containing a monomer component of 50% by weight or more in the photosensitive layer, the aluminum support of the present invention is further effective.

  In addition, when the molecular weight of the monomer component is 1000 or less, the use of the aluminum support of the present invention is particularly effective in reducing the occurrence of film loss failure in the lithographic printing plate and reducing the in-plane variation of the dot area. is there.

  Furthermore, in the case of a soft photosensitive layer such that the total Tg of the photosensitive layer is 50 ° C. or less, the use of the aluminum support of the present invention particularly causes a failure of a lithographic printing plate, particularly a film missing failure. Reduction and in-plane variation of halftone dot area are also effective in reducing. The total Tg is the glass transition temperature of the entire plurality of layers. Further, when the total Tg of the photosensitive layer is 30 ° C. or less, the aluminum support of the present invention is further effective.

  Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, an amino group or a mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and a monofunctional or polyfunctional compound. A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

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

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

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

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

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

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

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, JP-A-59- Those having an aromatic skeleton described in 5241 and JP-A-2-226149, those containing an amino group described in JP-A-1-165613, and the like are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  Also suitable are urethane-based addition-polymerizable compounds produced by the addition reaction of isocyanate and hydroxyl groups. Specific examples thereof include, for example, one molecule described in JP-B-48-41708. 2 or more polymerizable vinyl groups are contained in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following chemical formula (see Chemical Formula 2) to a polyisocyanate compound having 2 or more isocyanate groups. A vinyl urethane compound etc. are mentioned.

However, in the above-described chemical formula 2, Ra and Rb each represent H or CH ₃ .

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654, Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable. Further, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238, It is possible to obtain a photopolymerizable composition having a very high photosensitive speed.

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

  About these addition polymerizable compounds, the details of usage, such as the structure, single use or combined use, and addition amount can be arbitrarily set according to the final performance design. For example, it is selected from the following viewpoints. From the viewpoint of photosensitive speed, a structure having a high unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic ester, methacrylic ester, styrenic compound, A method of adjusting both photosensitivity and strength by using a vinyl ether compound) is also effective. A compound having a large molecular weight or a compound having high hydrophobicity is excellent in photosensitive speed and film strength, but is not preferable in terms of development speed and precipitation in a developer. In addition, the selection and use method of the addition polymerization compound is also an important factor for compatibility and dispersibility with other components in the photosensitive layer composition (for example, binder polymer, initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination.

  In the lithographic printing plate precursor according to the present invention, a specific structure may be selected for the purpose of improving adhesion to a support or a protective layer described later.

  Regarding the content of the addition polymerizable compound in the photosensitive layer composition, the solid content in the photosensitive layer composition is considered from the viewpoints of sensitivity, occurrence of phase separation, adhesiveness of the photosensitive layer, and precipitation from the developer. The amount is preferably 5 to 80% by mass, more preferably 40 to 75% by mass.

  These may be used alone or in combination of two or more. In addition, as for the method of using the addition polymerizable compound, an appropriate structure, blending, and addition amount can be arbitrarily selected from the viewpoints of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface tackiness, and the like. Furthermore, the lithographic printing plate precursor according to the present invention can also be subjected to a layer configuration / coating method such as undercoating or overcoating.

(Binder polymer)
The binder polymer used in the present invention is contained from the viewpoint of improving the film property, and various types can be used as long as it has a function of improving the film property. Among these, a binder polymer suitable in the present invention is a binder polymer having a repeating unit represented by the following chemical formula (Formula 3). Hereinafter, the binder polymer having a repeating unit represented by Chemical Formula 3 will be referred to as a specific binder polymer, and will be described in detail.

In the chemical formula of Chemical Formula 3, R ¹ represents a hydrogen atom or a methyl group, and R ² contains two or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. It represents a linking group that is composed of 2 to 82 total atoms. A represents an oxygen atom or —NR ³ —, and R ³ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. n represents an integer of 1 to 5.

First, R ¹ in Chemical Formula 3 represents a hydrogen atom or a methyl group, and a methyl group is particularly preferable.

The linking group represented by R ² in Chemical Formula 3 comprises two or more atoms selected from the group consisting of carbon atoms, hydrogen atoms, oxygen atoms, nitrogen atoms, and sulfur atoms, and the total number of atoms is 2 It is -82, Preferably it is 2-50, More preferably, it is 2-30. The total number of atoms shown here refers to the number of atoms including the substituent when the linking group has a substituent. More specifically, the number of atoms constituting the main skeleton of the linking group represented by R ² is preferably 1-30, more preferably 3-25, and 4-20. More preferred is 5-10. The “main skeleton of the linking group” in the present invention refers to an atom or an atomic group used only for linking A and the terminal COOH in Chemical Formula 3, particularly when there are a plurality of linking paths. The atom or atomic group which comprises the path | route with the fewest number of atoms used is pointed out. Therefore, when a linking group has a ring structure, the number of atoms to be included differs depending on the linking site (for example, o-, m-, p-, etc.).

  More specific examples include alkylene, substituted alkylene, arylene, substituted arylene, and the like, and a structure in which a plurality of these divalent groups are linked by an amide bond or an ester bond may be used.

  Examples of the linking group having a chain structure include ethylene and propylene. A structure in which these alkylenes are linked through an ester bond can also be exemplified as a preferable example.

Among these, the linking group represented by R ² in Chemical Formula 3 is preferably an (n + 1) -valent hydrocarbon group having an aliphatic cyclic structure having 3 to 30 carbon atoms. More specifically, a compound having an aliphatic cyclic structure such as cyclopropane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, dicyclohexyl, tercyclohexyl, norbornane and the like, which may be substituted by one or more arbitrary substituents And (n + 1) valent hydrocarbon groups by removing (n + 1) hydrogen atoms on an arbitrary carbon atom constituting. R ² preferably has 3 to 30 carbon atoms including substituents.

  One or more arbitrary carbon atoms of the compound constituting the aliphatic cyclic structure may be replaced with a heteroatom selected from a nitrogen atom, an oxygen atom, or a sulfur atom. In terms of printing durability, R2 represents condensed polycyclic aliphatic hydrocarbons, bridged cyclic aliphatic hydrocarbons, spiroaliphatic hydrocarbons, aliphatic hydrocarbon ring assemblies (in which multiple rings are connected by a bond or a linking group) And the like, (n + 1) -valent hydrocarbon group having an aliphatic cyclic structure which may have a substituent of 5 to 30 carbon atoms containing two or more rings. Also in this case, the carbon number includes the carbon atom of the substituent.

As the linking group represented by R ² , those having 5 to 10 atoms constituting the main skeleton of the linking group are particularly preferred, and are structurally a chain structure, and an ester bond in the structure. And those having a cyclic structure as described above are preferred.

  In the present invention, although depending on the design of the photosensitive layer, a substituent having a hydrogen atom capable of hydrogen bonding, and particularly a substituent having an acid dissociation constant (pKa) smaller than that of a carboxylic acid has a printing durability. Since it tends to lower, it is not preferable. On the other hand, hydrophobic substituents such as halogen atoms, hydrocarbon groups (alkyl groups, allyl groups, alkenyl groups, alkynyl groups), alkoxy groups, aryloxy groups and the like are more preferable because they tend to improve printing durability. When the cyclic structure is a monocyclic aliphatic hydrocarbon having 6 or less members such as cyclopentane or cyclohexane, it preferably has such a hydrophobic substituent. If possible, these substituents may be bonded to each other or with a substituted hydrocarbon group to form a ring, and the substituent may be further substituted.

R ³ in the case where A in Chemical Formula ³ is NR ³ — represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ³ include an alkyl group, an allyl group, an alkenyl group, and an alkynyl group.

  Specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isopropyl group, isobutyl group, sec-butyl group, 1 carbon number such as tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-norbornyl group Up to 10 linear, branched or cyclic alkyl groups.

  Specific examples of the allyl group include carbon having one heteroatom selected from the group consisting of an allyl group having 1 to 10 carbon atoms such as a phenyl group, a naphthyl group, and an indenyl group, a nitrogen atom, an oxygen atom, and a sulfur atom. Heteroallyl groups of 1 to 10 include, for example, furyl group, thienyl group, pyrrolyl group, pyridyl group, quinolyl group and the like.

  Specific examples of the alkenyl group include those having 1 to 10 carbon atoms such as vinyl group, 1-propenyl group, 1-butenyl group, 1-methyl-1-propenyl group, 1-cyclopentenyl group, 1-cyclohexenyl group and the like. A linear, branched, or cyclic alkenyl group is mentioned.

Specific examples of the alkynyl group include alkynyl groups having 1 to 10 carbon atoms such as ethynyl group, 1-propynyl group, 1-butynyl group, and 1-octynyl group. The substituent that R ³ may have is the same as those exemplified as the substituent that R ² can introduce. However, the carbon number of R < ³ > is 1-10 including the carbon number of a substituent.

  A in Chemical Formula 3 is preferably an oxygen atom or —NH— because synthesis is easy.

  N in Chemical Formula 3 represents an integer of 1 to 5, and is preferably 1 in terms of printing durability.

  In the following Chemical Formula 4, a plurality of preferred specific examples of the repeating unit represented by Chemical Formula 3 are shown, but the present invention is not limited thereto.

  One type of repeating unit represented by Chemical formula 3 may be contained in the binder polymer, or two or more types may be contained. The specific binder polymer in the present invention may be a polymer composed only of repeating units represented by Chemical Formula 3, but is usually used as a copolymer in combination with other copolymerization components. The total content of the repeating unit represented by Chemical Formula 3 in the copolymer is appropriately determined depending on the structure, the design of the photosensitive layer composition, etc., preferably 1 to 99 mol% with respect to the total molar amount of the polymer component, More preferably 5 to 40 mol%, still more preferably 5 to 20 mol%.

  As a copolymerization component in the case of using as a copolymer, a conventionally well-known thing can be used without a restriction | limiting if it is a monomer which can be radically polymerized. Specific examples include monomers described in “Polymer Data Handbook—Basic Edition” (Edition of Polymer Society, Bafukan, 1986). One type of such copolymerization component may be used, or two or more types may be used in combination.

  The molecular weight of the specific binder polymer in the present invention is appropriately determined from the viewpoint of image formability and printing durability. The molecular weight is preferably in the range of 2,000 to 1,000,000, more preferably 5,000 to 500,000, and still more preferably 10,000 to 200,000.

  The binder polymer used in the present invention may be a specific binder polymer alone, or may be used as a mixture by combining one or more other binder polymers. The binder polymer used in combination is used in the range of 1 to 60% by mass, preferably 1 to 40% by mass, and more preferably 1 to 20% by mass with respect to the total mass of the binder polymer component. As the binder polymer that can be used in combination, a conventionally known binder polymer can be used without limitation, and specifically, an acrylic main chain binder, a urethane binder, or the like often used in the industry is preferably used.

  Although the total amount of the specific binder polymer in the photosensitive layer composition and the binder polymer that may be used in combination can be determined as appropriate, it is usually 10 to 90 with respect to the total mass of nonvolatile components in the photosensitive layer composition. It is mass%, Preferably it is 20-80 mass%, More preferably, it is the range of 30-70 mass%.

  Further, the acid value (meg / g) of such a binder polymer is preferably in the range of 2.00 to 3.60.

<Other binder polymers that can be used in combination>
The other binder polymer that can be used in combination with the specific binder polymer is preferably a binder polymer having a radical polymerizable group.

The radical polymerizable group is not particularly limited as long as it can be polymerized by radicals, but α-substituted methylacrylic group [—OC (═O) —C (—CH ₂ Z) ═CH ₂ , Z = A hydrocarbon group starting from a hetero atom], an acryl group, a methacryl group, an allyl group, and a styryl group. Among these, an acryl group and a methacryl group are preferable.

  The content of the radical polymerizable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 1 g per binder polymer from the viewpoint of sensitivity and storage stability. It is 10.0 mmol, More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol.

  Further, the other binder polymer that can be used in combination is preferably one having an alkali-soluble group. The content of alkali-soluble groups in the binder polymer (acid value by neutralization titration) is preferably from 0.1 to 3.0 mmol, more preferably from 1 to 3.0 g of binder polymer, from the viewpoints of precipitation of developing residue and printing durability. Is 0.2 to 2.0 mmol, most preferably 0.45 to 1.0 mmol.

  The mass average molecular weight of such a binder polymer is preferably from 2,000 to 1,000,000, more preferably from 10,000 to 300, from the viewpoints of film properties (press life) and solubility in a coating solvent. In the range of 20,000 to 200,000.

  The glass transition point (Tg) of such a binder polymer is preferably 70 to 300 ° C, more preferably 80 to 250 ° C, most preferably from the viewpoint of storage stability, printing durability, and sensitivity. It is the range of 90-200 degreeC.

  As a means for increasing the glass transition point of the binder polymer, the molecule preferably contains an amide group or an imide group, and particularly preferably contains a methacrylamide methacrylamide derivative.

(Other ingredients)
The photosensitive layer of the lithographic printing plate precursor according to the invention may further contain other components suitable for its use and production method in addition to the above basic components. Hereinafter, preferred additives will be exemplified.

<Colorant>
A dye or pigment may be added to the photosensitive layer of the lithographic printing plate precursor according to the invention for the purpose of coloring. Thereby, so-called plate inspection properties such as image visibility after plate making as a printing plate and suitability for an image density measuring machine can be improved. Specific examples of the colorant include pigments such as phthalocyanine pigments, azo pigments, carbon black, and titanium oxide, and dyes such as ethyl violet, crystal violet, azo dyes, anthraquinone dyes, and cyanine dyes. Among them, a cationic dye is preferable.

  The addition amount of the dye and pigment as the colorant is preferably about 0.5% by mass to about 5% by mass with respect to the non-volatile components in the total photosensitive layer composition.

<Polymerization inhibitor>
In the photosensitive layer of the lithographic printing plate precursor according to the present invention, a compound having a polymerizable ethylenically unsaturated double bond, that is, a small amount of a thermal polymerization inhibitor is added in order to prevent unnecessary thermal polymerization of the polymerizable compound. It is desirable to add. Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the nonvolatile component in the photosensitive layer composition.

<Other additives>
Furthermore, the photosensitive layer of the lithographic printing plate precursor according to the present invention has an inorganic filler for improving the physical properties of the cured film, other plasticizers, and a sensitizer capable of improving the ink inking property on the surface of the photosensitive layer. You may add well-known additives, such as. Examples of plasticizers include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerin, and addition polymerization with binder polymer. Generally, it can be added in a range of 10% by mass or less based on the total mass with the compound.

  Further, in the photosensitive layer of the lithographic printing plate precursor according to the present invention, in order to enhance the effect of heating and exposure after development for the purpose of improving film strength (printing durability) described later, a UV initiator, A crosslinking agent or the like can also be added.

[Support]
Next, the aluminum support of the present invention will be described.

  The aluminum support is adopted as the most preferable and general support from all aspects. This aluminum plate is a metal plate mainly composed of dimensionally stable aluminum, and is selected from an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements in addition to a pure aluminum plate. In the following description, the above-mentioned support made of aluminum or an aluminum alloy is generically used as an aluminum support. Examples of the foreign element contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of the foreign element in the alloy is 10% by mass or less. In the present invention, a pure aluminum plate is suitable, but since completely pure aluminum is difficult to manufacture in the refining technique, it may contain a slightly different element. Thus, the composition of the aluminum plate applied to the present invention is not specified, and it is a conventional publicly known material, such as JIS A 1050, JIS A 1100, JIS A 3103, JIS A 3005, etc. Can be used as appropriate.

  The thickness of the aluminum support is about 0.1 mm to 0.6 mm. This thickness can be changed as appropriate according to the size of the printing press, the size of the printing plate, and the desire of the user.

  The aluminum support of the present invention is an aluminum support for a lithographic printing plate on which an electrochemical roughening treatment is performed, and the surface roughness before the roughening treatment is a centerline average roughness Ra. It is comprised so that it may be 0.10 micrometer or more and 0.24 micrometer or less.

  The quality of the lithographic printing plate precursor according to the present invention depends on the centerline average roughness Ra, which is a factor of the surface shape of the support. This Ra needs to satisfy the condition that it is in the range of 0.10 μm or more and 0.24 μm or less, preferably 0.15 μm or more and 0.20 μm or less.

  Here, the center line average roughness Ra refers to the center line average roughness (arithmetic average roughness) perpendicular to the aluminum rolling direction. From the roughness curve measured with a stylus, the direction of the center line When the portion of the measurement length L is extracted, the center line of the extracted portion is the X axis, the axis perpendicular to the X axis is the Y axis, and the roughness curve is expressed by y = f (x), The value given by the equation is expressed in units of μm. In addition, determination of L and measurement of average roughness follow JIS B 0601 1982.

  In order to satisfy the above-described conditions for the surface roughness Ra of the support thus calculated, the surface of the rolling roller is mirror-finished when an ingot as a support material is rolled to form an aluminum plate. You may adopt the method of doing. Moreover, when rolling, it can achieve also by the method of adjusting the rolling time by reducing the pressure to roll and performing multistage rolling. Furthermore, these two methods may be combined.

  In general, it is effective to increase the surface roughness of the aluminum support thus obtained, but it is effective to increase the surface roughness. Since the concave portion causes development failure and a residual film is likely to be generated, Ra needs to be within the following range. That is, in the present invention, Ra needs to be in the range of 0.20 to 0.40 μm, preferably in the range of 0.20 to 0.35 μm, and more preferably in the range of 0.25 to 0.35 μm. It is a range. Therefore, the surface treatment described later is performed on the aluminum support.

  When the above-described aluminum alloy plate is employed as a support for a lithographic printing plate precursor, the surface treatment (also referred to as roughening treatment) is an electrochemical surface treatment, for example, a rough surface having fine irregularities due to electrolytic grains. Therefore, it is suitable for producing a lithographic printing plate having excellent printability. The electrochemical surface treatment is performed using direct current or alternating current in an aqueous solution mainly composed of nitric acid or hydrochloric acid.

An anode electricity quantity suitable method useful surface roughening is in the range of ^{50C / dm 2 ~400C / dm 2} . More specifically, in an electrolytic solution containing 0.1 to 50% hydrochloric acid or nitric acid, the temperature is 20 to 80, the time is 1 second to 30 minutes, and the current density is 10 A / dm ^{2 to} 50 A / dm ^2. It is preferable to perform direct current electrolysis.

  A crater or honeycomb-like pit having an average diameter of about 0.5 to 20 μm can be generated on the surface of the aluminum alloy plate at an area ratio of 30 to 100% by electrochemical roughening treatment. Such pits have the effect of improving the resistance to smearing of the non-image area of the printing plate and the printing durability. Further, by this treatment, a wavy rough surface having a center line average roughness Ra of 0.2 to 0.6 μm is formed at the same time.

  In the electrochemical surface roughening treatment, the amount of electricity required to form sufficient pits, that is, the product of the current and the energization time is an important requirement in the electrochemical surface roughening treatment. If sufficient pits can be formed with a smaller amount of electricity, it is preferable from the viewpoint of energy saving. Other conditions are not particularly limited.

  The roughened aluminum support may be chemically etched with acid or alkali. Etching agents suitably used are caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. Preferred ranges of concentration and temperature are 1 to 50% and 20%, respectively. ~ 100. In order to remove dirt (smut) remaining on the surface after etching, pickling is performed. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borohydrofluoric acid and the like are used.

  In particular, as a method for removing smut after the electrochemical surface roughening treatment, it is preferably contacted with 15 to 65 mass% sulfuric acid at 50 to 90 ° C. as described in JP-A-53-12739. Examples thereof include alkali etching and a method described in Japanese Patent Publication No. 48-28123.

Subsequent to the roughening treatment, an anodizing treatment is performed in order to improve the wear resistance of the surface of the aluminum alloy plate. Any electrolyte may be used as long as it forms a porous oxide film. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixture thereof is used. The concentration of the electrolyte is appropriately determined depending on the type of electrolyte. The conditions of the anodizing treatment vary considerably depending on the electrolyte, so it is difficult to specify, but generally, the concentration of the electrolyte is 1 to 80% by mass, the liquid temperature is 5 to 70 ° C., the current density is 1 to 60 A / dm ² , The voltage may be 1 to 100 V and the electrolysis time may be 10 to 300 seconds.

  In order to avoid stains during printing, the aluminum alloy plate is subjected to an electrochemical roughening treatment and washing with water, followed by mild etching with an alkaline solution, washing with water, desmutting with sulfuric acid, and washing with water. Then, direct current electrolysis may be performed in sulfuric acid to provide an anodized film. Furthermore, if necessary, a hydrophilic treatment with silicate or the like may be performed.

A widely known method can be applied as the hydrophilic treatment on the surface of the support. As a particularly preferable treatment, a hydrophilic treatment with silicate or polyvinylphosphonic acid is performed. A film | membrane is formed by 2-40 mg / m < ² > as Si or P element amount, More preferably, it is 4-30 mg / m < ² >. The coating amount can be measured by fluorescent X-ray analysis.

  In the above hydrophilization treatment, an alkali oxide silicate or polyvinylphosphonic acid is 1 to 30% by mass, preferably 2 to 15% by mass, and an anodic oxide film is formed on an aqueous solution having a pH of 10 to 13. The aluminum support thus obtained is immersed, for example, at 15 to 80 ° C. for 0.5 to 120 seconds.

  As the alkali metal silicate used for the hydrophilization treatment, sodium silicate, potassium silicate, lithium silicate, or the like is used.

  Such an aluminum support is roughened.

(Roughening treatment)
Electrochemical roughening methods include chemical etching and electrolytic graining. Furthermore, an electrochemical surface roughening method in which the surface is electrochemically roughened in hydrochloric acid or nitric acid electrolyte can be used, and the above surface roughening methods can be used alone or in combination. Suitable anodic time electricity is in the range of ^{50C / dm 2 ~400C / dm 2} . More specifically, the temperature in the electrolyte containing 0.1 to 50% hydrochloric acid or nitric acid is 20 to 80 ° C., the time is 1 second to 30 minutes, and the current density is 100 C / dm ^{2 to} 400 C / It is preferable to perform alternating current and / or direct current electrolysis under the condition of dm ² .

  The roughened aluminum support may be chemically etched with acid or alkali. Etching agents suitably used are caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide and the like, and preferred ranges of concentration and temperature are 1 to 50% and 20%, respectively. ~ 100 ° C. In order to remove dirt (smut) remaining on the surface after etching, pickling is performed. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borohydrofluoric acid and the like are used. In particular, as a method for removing smut after the electrochemical surface roughening treatment, contact with 15 to 65 mass% sulfuric acid at 50 to 90 ° C. as described in JP-A-53-12739 is preferable. And the alkali etching method described in Japanese Patent Publication No. 48-28123. After the treatment as described above, the method and conditions are not particularly limited as long as the surface roughness Ra of the treated surface is about 0.2 to 0.5 μm.

(Anodizing treatment)
The aluminum support that has been treated as described above to form an oxide layer is then anodized.

In the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, or an aqueous solution of boric acid / sodium borate is used alone or in combination as a main component of the electrolytic bath. In this case, the electrolyte solution may of course contain at least components normally contained in at least an Al alloy plate, an electrode, tap water, groundwater and the like. Further, the second and third components may be added. There are no particular limitations on the conditions for the anodizing treatment, but the treatment is preferably carried out by direct current or alternating current electrolysis at a current density of 0.1 to 40 A / m ² at 30 to 500 g / L, a treatment liquid temperature of 10 to 70 ° C. The The thickness of the formed anodized film is in the range of 0.5 to 1.5 μm, preferably in the range of 0.5 to 1.0 μm. The support prepared by the above treatment is treated so that the pore diameter of the micropores existing in the anodized film is in the range of 5 to 10 nm and the pore density is in the range of 8 × 10 ¹⁵ to 2 × 10 ¹⁶ pieces / m ^2. It is preferred that the conditions are selected.

A widely known method can be applied as the hydrophilic treatment on the surface of the support. As a particularly preferable treatment, a hydrophilic treatment with silicate or polyvinylphosphonic acid is performed. A film | membrane is formed by 2-40 mg / m < ² > as Si or P element amount, More preferably, it is 4-30 mg / m < ² >. The coating amount can be measured by fluorescent X-ray analysis.

  The hydrophilization treatment is carried out by adding an alkali metal silicate or polyvinylphosphonic acid in an aqueous solution of 1 to 30% by mass, preferably 2 to 15% by mass, and at 25 ° C. and pH 10 to 13 with an anodized film. This is carried out by immersing the aluminum support on which is formed, for example, at 15 to 80 ° C. for 0.5 to 120 seconds.

  As the alkali metal silicate used for the hydrophilization treatment, sodium silicate, potassium silicate, lithium silicate, or the like is used. Examples of the hydroxide used for increasing the pH of the aqueous alkali metal silicate solution include sodium hydroxide, potassium hydroxide, and lithium hydroxide. In addition, you may mix | blend alkaline-earth metal salt or Group IVB metal salt with said process liquid. Alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate, and water-soluble substances such as sulfate, hydrochloride, phosphate, acetate, oxalate, and borate. Salt. Group IVB metal salts include titanium tetrachloride, titanium trichloride, potassium fluoride titanium, potassium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride, zirconium tetrachloride, etc. Can be mentioned.

  Alkaline earth metal salts or Group IVB metal salts can be used alone or in combination of two or more. A preferable range of these metal salts is 0.01 to 10% by mass, and a more preferable range is 0.05 to 5.0% by mass. Silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective. A support with electrolytic grains as disclosed in JP-B-46-27481, JP-A-52-58602, and JP-A-52-30503 is combined with the above-described anodizing treatment and hydrophilization treatment. Surface treatment is also useful.

[Preparation of lithographic printing plate precursor]
The original plate of the lithographic printing plate according to the present invention is provided with a photosensitive layer and a protective layer in this order on a support, and further, if necessary, an undercoat layer. Such a lithographic printing plate precursor can be produced by dissolving a coating solution containing the above-described various components in a suitable solvent and coating the solution on a support.

  When coating the photosensitive layer, the photosensitive layer components are dissolved in various organic solvents to form a photosensitive layer coating solution, which is applied onto the support or the undercoat layer.

  Solvents used here include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, Ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, lactic acid There is ethyl. These solvents can be used alone or in combination. The solid content in the photosensitive layer coating solution is suitably 2 to 50% by mass.

The coating amount of the photosensitive layer mainly affects the sensitivity of the photosensitive layer, the developability, and the strength and printing durability of the exposed film, and is preferably selected as appropriate according to the application. When the coating amount is too small, the printing durability is not sufficient. On the other hand, if the amount is too large, the sensitivity is lowered, it takes time for exposure, and a longer time is required for development processing, which is not preferable. For the lithographic printing plate precursor for scanning exposure, the coating amount is suitably in the range of about 0.1 g / m ² to about 10 g / m ² in terms of the mass after drying. More preferably from 0.5 to 5 g / m ^2.

[Intermediate layer (undercoat layer)]
In the lithographic printing plate precursor according to the invention, an intermediate layer (undercoat layer) may be provided for the purpose of improving the adhesion and soiling between the photosensitive layer and the support. Specific examples of such an intermediate layer include JP-B-50-7481, JP-A-54-72104, JP-A-59-101651, JP-A-60-149491, JP-A-60-232998, JP-A-3-56177, JP-A-4-282737, JP-A-5-16558, JP-A-5-246171, JP-A-7-159983, JP-A-7-314937, JP-A-8-202025, Special Kaihei 8-320551, JP 9-34104, JP 9-236911, JP 9-269593, JP 10-69092, JP 10-115931, JP 10-161317, JP No. 10-260536, JP-A-10-282682, JP-A-11-84684, and the like.

[Protective layer]
Since the photosensitive layer of the lithographic printing plate precursor according to the present invention is a polymerizable negative photosensitive layer as described above, it is usually further protected on the photosensitive layer in order to perform exposure in the air. It is necessary to provide a layer (also referred to as an overcoat layer). The protective layer prevents exposure of low molecular weight compounds such as oxygen and basic substances present in the atmosphere that hinder the image formation reaction caused by exposure in the photosensitive layer, and enables exposure in the atmosphere. To do. Therefore, the properties desired for such a protective layer are low permeability of low-molecular compounds such as oxygen, and further, transmission of light used for exposure is not substantially inhibited, and adhesion to the photosensitive layer is excellent. And it is desirable that it can be easily removed in the development process after exposure. Such a device relating to the protective layer has been conventionally made, and is described in detail in US Pat. No. 3,458,311 and JP-B-55-49729. As a material that can be used for the protective layer, for example, a water-soluble polymer compound having relatively excellent crystallinity is preferably used. Specifically, polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, Water-soluble polymers such as acrylic acid are known, but among these, the use of polyvinyl alcohol as a main component gives the best results in terms of basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol used for the protective layer may be partially substituted with an ester, an ether and an acetal as long as it contains an unsubstituted vinyl alcohol unit for having necessary oxygen barrier properties and water solubility. Similarly, some of them may have other copolymer components. Specific examples of polyvinyl alcohol include those having a hydrolysis rate of 71 to 100% and a molecular weight in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, L-8 and the like.

  Components of the protective layer (selection of PVA, use of additives), coating amount, and the like are selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of the PVA used (the higher the content of the unsubstituted vinyl alcohol unit in the protective layer), the thicker the film thickness, the higher the oxygen barrier property, which is advantageous in terms of sensitivity. However, when the oxygen barrier property is extremely increased, there arises a problem that unnecessary polymerization reaction occurs during production and raw storage, and unnecessary fogging and image line thickening occur during image exposure. Also, adhesion to the image area and scratch resistance are extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on an oleophilic photosensitive layer, film peeling due to insufficient adhesive force is likely to occur, and the peeled part causes defects such as poor film hardening due to inhibition of oxygen polymerization. On the other hand, various proposals have been made to improve the adhesion between these two layers. For example, U.S. Patent Application No. 292,501 and U.S. Patent Application No. 44,563 disclose an acrylic emulsion or a water-insoluble vinylpyrrolidone-vinyl acetate copolymer in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass and the like and laminating on the photosensitive layer.

  Any of these known techniques can be applied to the protective layer in the present invention. Such a coating method of the protective layer is described in detail in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

Therefore, in the present invention, it is preferable to use polyvinyl alcohol and polyvinyl pyrrolidone in combination from the viewpoints of adhesive strength, sensitivity, and unnecessary fog. The addition amount ratio (mass ratio) is preferably 3: 1 or less of polyvinyl alcohol: polyvinylpyrrolidone. The coating weight is preferably ^{1.0g / m 2 ~3.0g / m 2} .

  The lithographic printing plate precursor configured as described above is characterized in that it is subjected to exposure processing at a wavelength of 750 nm to 1400 nm and then subjected to development processing to be subjected to plate making. Hereinafter, the plate making method according to the present invention will be described.

〔exposure〕
The light source used for the exposure treatment in the present invention may be any light source as long as it can be exposed at a wavelength of 750 nm to 1400 nm, and an infrared laser is preferable. Especially, in this invention, it is preferable to image-expose with the solid laser and semiconductor laser which radiate | emit infrared rays with a wavelength of 750 nm-1400 nm. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec. The energy applied to the planographic printing plate precursor is preferably 10 to 300 mJ / cm ² . If the exposure energy is too low, the photosensitive layer is not sufficiently cured. If the exposure energy is too high, the photosensitive layer may be laser ablated and the image may be damaged.

  In the exposure processing in the present invention, exposure can be performed by overlapping light beams of light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.

  The scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, or the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.

  In the present invention, the exposed lithographic printing plate precursor is subjected to development processing. Further, by performing neither heat treatment nor water washing treatment, stable high-speed processing is possible in development processing.

〔developing〕
The developer used in the present invention preferably has a pH in the range of 10 to 12.5 at 25 ° C, more preferably in the range of pH 11 to 12.5. Since the developer in the present invention contains the surfactant, even if such a low pH developer is used, excellent developability is exhibited in the non-image area. Thus, by setting the pH of the developing solution to a relatively low value, damage to the image area during development is reduced and the handling property of the developing solution is excellent.

  The developer can be used as a developer and a development replenisher for the exposed lithographic printing plate precursor, and is preferably applied to an automatic processor. When developing using an automatic developing machine, the developing solution becomes fatigued according to the amount of processing, so that the processing capability may be restored by using a replenishing solution or a fresh developing solution. This replenishment method is also preferably applied to the plate making method of the present invention. By using the developer for the development of the lithographic printing plate precursor described above, the effect of the present invention is particularly remarkable, which is preferable. That is, the developer according to the present invention is a negative lithographic plate in which a photosensitive layer containing an infrared absorber, a polymerization initiator, a polymerizable compound, and a binder polymer and a protective layer are sequentially laminated on a support. It is a developer suitable for a printing plate precursor.

  Furthermore, in order to restore the processing capacity of the developer using an automatic developing machine, it is preferable to replenish by the method described in US Pat. No. 4,882,246. Developers described in JP-A-50-26601, 58-54341, JP-B-56-39464, 56-42860, and 57-7427 are also preferable.

  The lithographic printing plate precursor thus developed is subjected to washing water, surface activity as described in JP-A Nos. 54-8002, 55-11545, 59-58431, and the like. It is post-treated with a desensitizing solution containing a rinse solution containing an agent and the like, gum arabic and starch derivatives. These treatments can be used in various combinations for the post-treatment of the lithographic printing plate precursor according to the invention. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing a large number of sheets.

  In the lithographic printing plate precursor according to the present invention, the entire image after development can be subjected to full post-heating or full exposure for the purpose of improving image strength and printing durability.

  Very strong conditions can be used for heating after development. Usually, the heating temperature is 200 to 500 ° C. If the heating temperature after development is low, sufficient image strengthening action cannot be obtained, and if it is too high, problems such as deterioration of the support and thermal decomposition of the image area may occur.

  The planographic printing plate made by the above processing is loaded on an offset printing machine and used for printing a large number of sheets.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

<Example 1>
In Example 1, the following surface treatment was performed using an aluminum plate of JIS A 1050 having a thickness of 0.30 mm and a width of 1030 mm as an aluminum support.

[Roughening of support]
In the roughening treatment, the following various treatments (a) to (f) were continuously performed. After each treatment and washing with water, the liquid was removed with a nip roller.

(A) The aluminum plate was etched at a caustic soda concentration of 26% by mass, an aluminum ion concentration of 6.5% by mass and 70 ° C. to dissolve the aluminum plate by 5 g / m ² . Thereafter, it was washed with water.

  (B) A desmut treatment was performed by spraying with a 1% by mass aqueous solution of nitric acid having a nitric acid concentration of 30 (including 0.5% by mass of aluminum ions), and then washed with water.

(C) An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass aqueous solution of nitric acid at 30 ° C. (including 0.5% by mass of aluminum ions and 0.007% by mass of ammonium ions). The AC power source uses a trapezoidal rectangular wave AC with a time TP of 2 msec until the current value reaches a peak from zero and a duty ratio of 1: 1, and an electrochemical surface roughening treatment using a carbon electrode as a counter electrode. Was done. Ferrite was used for the auxiliary anode. The current density was 25 A / dm ² at the current peak value, and the amount of electricity was 250 C / cm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Thereafter, it was washed with water.

(D) The aluminum plate was etched by spraying at 35 ° C. with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, the aluminum plate was dissolved at 0.2 g / m ² , and the previous stage AC was used. The removal of the smut component mainly composed of aluminum hydroxide produced during electrochemical surface roughening and the edge part of the produced pit were dissolved to smooth the edge part. Then, it washed with water.

  (E) A desmut treatment by spraying was performed with an aqueous solution having a sulfuric acid concentration of 25% by mass (containing 0.5% by mass of aluminum ions) at 60 ° C., followed by washing with water by spraying.

(F) Anodizing was performed for 50 seconds at a sulfuric acid concentration of 170 g / L (containing 0.5 mass% of aluminum ions), 33 ° C., and a current density of 5 (A / dm ² ). Then, it washed with water. At this time, the weight of the anodized film was 2.7 g / m ² .

  The centerline average roughness Ra of the aluminum support after the electrochemical surface roughening treatment thus obtained was Ra = 0.27 (measuring instrument: Surfcom manufactured by Tokyo Seimitsu Co., Ltd., stylus tip diameter) 2 μm).

[Formation of undercoat layer]
Next, the following undercoat layer coating solution was applied to the aluminum support with a wire bar and dried at 90 ° C. for 30 seconds. The coating amount was 10 mg / m ² .

(Coating solution for undercoat layer)
-Polymer compound A having the structure shown in the following chemical formula 5; 0.05 g
・ Methanol; 27g
・ Ion exchange water; 3g

[Formation of photosensitive layer]
Next, a photosensitive layer coating solution [P-1] having the composition shown in Table 1 below was prepared and applied to the aluminum support using a wire bar. Drying was performed at 115 ° C. for 34 seconds using a hot air drying apparatus to obtain a lithographic printing plate precursor. The coating amount after drying was 1.3 g / m ² .

  In addition, the polymerization initiator (OS-12) used for the said photosensitive layer coating liquid points out what is mentioned as a compound example of the onium salt represented by the above-mentioned general formula (1). The structures of the infrared absorber (IR-1), additive (PM-1), polymerizable compound (AM-1), binder polymer (BT-1), and ethyl violet (C-1) are shown below. .

[Protective layer (overcoat layer)]
A mixed aqueous solution of polyvinyl alcohol (saponification degree 98 mol%, polymerization degree 500) and polyvinyl pyrrolidone (BASF Corp., Rubiscol K-30) was applied to the photosensitive layer surface with a wire bar, The sample was dried at 125 ° C. for 75 seconds using a type dryer. The content ratio of polyvinyl alcohol: polyvinylpyrrolidone was 4: 1% by mass, and the coating amount (the coating amount after drying) was 2.30 g / m ² .

[Evaluation]
The original lithographic printing plate thus obtained was changed by a 0.15 increment in log E at 0.15 with a resolution of 2400 dpi, external drum rotation speed 150 rpm, output 0 to 8 W, using a Trend setter 3244 manufactured by Creo as an image portion. Exposed. The exposure was performed under conditions of 25 ° C. and 50% RH. After the exposure, neither heat treatment nor water washing treatment was performed, and development processing was performed at a conveyance speed (line speed) of 2 m / min and a development temperature of 30 ° C. using an automatic developing machine LP-1310HII manufactured by FUJIFILM Corporation. In addition, the thing of the composition shown below was used for the developing solution, and the 1: 1 water dilution liquid of Fuji Film Co., Ltd. GN-2K was used for the finisher.

(Developer)
The following components were dissolved in water, and a developer was prepared so that the pH was 11.95 (25 ° C.) with KOH.

・ Surfactant (K-1): 4.00% by mass
・ Ethylenediaminetetraacetic acid 4Na salt: 0.16% by mass
・ Potassium carbonate: 0.16% by mass
The lithographic printing plate developed in this manner was visually inspected for the absence of an image on the plate, that is, the presence or absence of “film loss”, and the number thereof was counted. At this time, a film having a part longer than 0.01 mm was regarded as film removal.

  The result is shown in FIG. FIG. 1 is a graph showing the number of film loss failures of a lithographic printing plate produced as described above with respect to the centerline average roughness Ra of the aluminum support before the electrochemical surface roughening treatment in Example 1. is there.

  From the graph of FIG. 1, when the center line average roughness Ra of the aluminum support before the surface roughening treatment is 0.24 μm or less, the number of film loss failures of the lithographic printing plate is substantially zero, whereas the center line average It can be seen that when the roughness Ra exceeds 0.24 μm, the number of film loss failures of the lithographic printing plate increases rapidly. Although not shown, the in-plane variation of the halftone dot area in the planographic printing plate was also reduced.

  FIG. 2 is a graph showing the number of film loss failures of the lithographic printing plate produced as described above with respect to the maximum roughness Rmax of the aluminum support before the electrochemical surface roughening treatment in Example 1.

  From the graph of FIG. 2, when the maximum roughness Rmax of the aluminum support before the surface roughening treatment is 1.6 μm or less, the number of film loss failures of the lithographic printing plate is 5 or less, whereas the maximum roughness Rmax When the thickness exceeds 1.6 μm, it can be seen that the number of film loss failures of the lithographic printing plate increases rapidly. Although not shown, the in-plane variation of the halftone dot area in the planographic printing plate was also reduced.

  Accordingly, the aluminum support for a lithographic printing plate has a surface roughness before the electrochemical surface roughening treatment is 0.10 μm or more and 0.24 μm or less in terms of the center line average roughness Ra. It is preferably 0.10 μm or more and 0.20 μm or less, more preferably 0.15 μm or more and 0.20 μm or less. The maximum roughness Rmax is preferably 1.6 μm or less, and more preferably 1.3 μm or less.

  Furthermore, the surface roughness before the chemical roughening treatment is 0.10 μm or more and 0.24 μm or less in terms of the center line average roughness Ra, and 1.6 μm or less in terms of the maximum roughness Rmax. More preferably. The center line average roughness Ra is more preferably 0.10 μm or more and 0.20 μm or less, and the maximum roughness Rmax is further preferably 1.6 μm or less. The center line average roughness Ra is particularly preferably 0.15 μm or more and 0.20 μm or less, and the maximum roughness Rmax is particularly preferably 1.3 μm or less.

  From this, by using the aluminum support of the present invention to produce an original plate of a lithographic printing plate for CTP, it is possible to reliably reduce film dropout failure. Therefore, a high-quality lithographic plate usable for CTP It has been found that a printing plate precursor can be produced stably.

The graph which showed the number of film dropouts of the lithographic printing plate with respect to the centerline average roughness Ra of the aluminum support in Example 1 The graph which showed the number of film drop-out failures of the lithographic printing plate with respect to the maximum roughness Rmax of the aluminum support in Example 1

Claims (6)

  An aluminum support for a lithographic printing plate subjected to an electrochemical surface roughening treatment, wherein the surface roughness before the surface roughening treatment is 0.10 μm or more and 0.24 μm or less in terms of centerline average roughness Ra An aluminum support for a lithographic printing plate, characterized in that   An aluminum support for a lithographic printing plate on which an electrochemical surface roughening treatment is performed, wherein the surface roughness before the surface roughening treatment is 1.6 μm or less at a maximum roughness Rmax. Aluminum support for lithographic printing plates.   A photosensitive layer containing an infrared absorber, a polymerization initiator, a polymerization compound, and a binder polymer and a protective layer are coated on the aluminum support for a lithographic printing plate according to claim 1 or 2. A lithographic printing plate.   4. The lithographic printing plate according to claim 3, wherein the photosensitive layer contains 25% by weight or more of a monomer component.   The lithographic printing plate according to claim 4, wherein the molecular weight of the monomer component is 1000 or less.   The lithographic printing plate according to any one of claims 2 to 5, wherein the total Tg of the photosensitive layer is 50 ° C or less.

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