JP2006065210A - Photosensitive lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive lithographic printing plate which satisfies developability while having high sensitivity and high printing durability, causes no stain during printing, and can be suitably used particularly for CTP technique. <P>SOLUTION: In the photosensitive lithographic printing plate having, on a support, a photopolymerizable photosensitive layer containing an addition polymerizable compound having an ethylenically unsaturated double bond, an alkali-soluble or -swellable binder and a photopolymerization initiator, the photopolymerizable photosensitive layer contains (a) a urethane group-containing (meth)acrylate compound having a molecular weight of ≤800 and no alkylene oxide moiety and (b) a (meth)acrylate compound having an alkylene oxide moiety in a linking group and also having two ethylenically unsaturated double bonds, as the addition polymerizable compound having an ethylenically unsaturated double bond. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photosensitive lithographic printing plate using a photopolymerizable composition. In particular, the present invention relates to a photosensitive lithographic printing plate for direct drawing that has both high sensitivity and high printing durability while achieving both developability.

Negative photosensitive lithographic printing plates are generally coated with a photosensitive composition on a roughened aluminum plate or the like, exposed to a desired image, and image portions (light irradiated portions). Is polymerized or crosslinked to be insolubilized in a developer, and image formation is performed by a process of eluting non-image areas with the developer. Conventionally, photopolymerizable compositions are well known as photosensitive compositions used for such purposes.
In recent years, digitization technology for electronically processing, storing, and outputting image information by a computer has become widespread. For example, CTP (Computer-To-Plate) technology for scanning a highly directional light such as laser light according to digitized image information and directly producing a printing plate without using a lith film is desired. Development of high-sensitivity printing original plates adapted to the above has progressed.

  As this light source, Ar ion laser (488 nm) and FD-YAG laser (532 nm) are used, and photosensitive lithographic printing plates having a photopolymerizable photosensitive layer applied to these light sources have been developed and put into practical use. . Recently, an InGaN-based semiconductor laser (violet laser, 350 nm to 450 nm) has been developed, and a bright room, lower cost of the exposure machine, and higher productivity are expected. The development of lithographic printing plates having a polymerizable photosensitive layer has been accelerated. As a photopolymerizable composition sensitive to Ar ion laser and FD-YAG laser, a composition containing a combination initiation system of titanocene and coumarin dye described in Patent Documents 1 and 2, etc., and a styryl system described in Patent Document 3 As a composition containing a combination initiation system of a dye and titanocene, and a photopolymerizable composition sensitive to violet laser, a photopolymerizable composition having a carbazolyl styryl dye described in Patent Document 4 is known. .

  When these photopolymerizable compositions are applied as lithographic printing plates, these photopolymerizable photosensitive layers are usually provided on a support, and polyvinyl alcohol or the like for the purpose of preventing oxygen that inhibits polymerization thereon. It is used in a form provided with an oxygen barrier layer. With the photopolymerizable composition, it has become possible to obtain a relief image exhibiting high sensitivity, but on the other hand, it is difficult to achieve compatibility with developability, and due to fluctuations in printing plate storage conditions and development processing conditions, residual film and Improvement has been desired because it causes smearing during printing.

JP-A-9-268185 Japanese Patent Laid-Open No. 10-204085 Japanese Patent Laid-Open No. 9-80750 JP 2001-42524 A

  Accordingly, an object of the present invention is to provide a photosensitive lithographic printing plate that has high sensitivity and high printing durability, has both developability and does not cause smearing during printing, and can be suitably used particularly for CTP technology. That is.

The present inventor has determined that the ability to dilute the monomer and the liquid permeability have a great influence on the compatibility between the sensitivity and the developability of the lithographic printing plate provided with the photopolymerizable photosensitive layer, and measures to reduce the influence As a result of diligent investigation, the linking group has an alkylene oxide moiety that has high diluting ability, improves the liquid permeability of the non-image area, and maintains the sensitivity without changing the developer permeability of the image area (meta) It has been found that by addressing the photopolymerizable photosensitive layer with an acrylate compound, it is possible to achieve compatibility with developability without degrading performance such as sensitivity.

That is, the present invention is as follows.
(1) Photosensitive lithographic printing having a photopolymerizable photosensitive layer containing an addition-polymerizable compound having an ethylenically unsaturated double bond, an alkali-soluble or swellable binder, and a photopolymerization initiator on a support In the plate, the photopolymerizable photosensitive layer is an addition-polymerizable compound having an ethylenically unsaturated double bond. (A) Urethane group containing (meth) having a molecular weight of 800 or less and having no alkylene oxide moiety A photosensitive lithographic printing plate comprising an acrylate compound and (b) a (meth) acrylate compound having an alkylene oxide moiety in a linking group and having two ethylenically unsaturated double bonds.

  (2) The photosensitive lithographic printing plate as described in (1) above, wherein the photosensitive wavelength of the photopolymerizable photosensitive layer is in the range of 350 nm to 450 nm.

  (3) (a) urethane group-containing (meth) acrylate compound having a molecular weight of 800 or less and not having an alkylene oxide moiety, and (b) an linking group having an alkylene oxide moiety and an ethylenically unsaturated double bond (1) or (2) above, wherein the mass ratio of the (meth) acrylate compound having 2 is in the range of 9: 1 to 2: 8 as the compound (a) :( b) Photosensitive lithographic printing plate.

  According to the present invention, it is possible to provide a photosensitive lithographic printing plate that has high sensitivity and high printing durability, has both developability and does not cause stains during printing, and can be suitably used particularly for CTP technology. it can.

The photosensitive lithographic printing plate of the present invention will be described in detail.
The photosensitive lithographic printing plate of the present invention has a photopolymerizable photosensitive layer, preferably a protective layer (oxygen barrier layer) on a support. Moreover, you may provide an undercoat layer between a support body and a photopolymerizable photosensitive layer as needed.

<1. Support>
In order to obtain a lithographic printing plate, which is one of the main objects of the present invention, it is desirable to provide the photosensitive layer on a support having a hydrophilic surface. As the hydrophilic support, a conventionally known hydrophilic support used in a lithographic printing plate can be used without limitation. The support used is preferably a dimensionally stable plate, for example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc). , Copper, etc.), plastic films (for example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.) Paper or plastic film, etc., laminated or vapor-deposited with such metals is included, and appropriate physical and chemical treatments are applied to these surfaces for the purpose of imparting hydrophilicity and improving strength as necessary. You may give it.

In particular, preferred supports include paper, polyester film or aluminum plate, among which dimensional stability is good, relatively inexpensive, and a surface with excellent hydrophilicity and strength is provided by surface treatment as required. An aluminum plate which can be used is particularly preferred. A composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 is also preferable.

  The aluminum substrate is a metal plate mainly composed of dimensionally stable aluminum. In addition to a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or aluminum (alloy) is laminated or Selected from vapor-deposited plastic film or paper.

In the following description, the above-mentioned substrates made of aluminum or an aluminum alloy are generically used as an aluminum substrate. 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 completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element.
Thus, the composition of the aluminum plate applied to the present invention is not specified, and conventionally known and used materials such as JIS A 1050, JIS A 1100, JIS A 3103, JIS A 3005, etc. It can be used as appropriate. The thickness of the aluminum substrate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, particularly preferably 0.2 mm to 0.3 mm. This thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, and the user's desire. The aluminum substrate may be subjected to a substrate surface treatment described later as necessary. Of course, it may not be applied.

(Roughening treatment)
The aluminum substrate is usually roughened. Examples of the roughening treatment method include mechanical roughening, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Electrochemical roughening method that further electrochemically roughens in hydrochloric acid or nitric acid electrolyte solution, and a wire brush grain method in which the aluminum surface is scratched with a metal wire, and a pole in which the aluminum surface is grained with a polishing ball and an abrasive. A mechanical roughening method such as a grain method or a brush grain method in which the surface is roughened with a nylon brush and an abrasive can be used, and the above roughening methods can be used alone or in combination. Among them, a method usefully used for roughening is an electrochemical method in which roughening is chemically carried out in hydrochloric acid or nitric acid electrolyte, and a suitable anodic electricity is 50 C / dm ^{2 to} 400 C / dm ² . It is a range. More specifically, in the electrolytic solution containing from 0.1 to 50% hydrochloric acid or nitric acid, the temperature 20 to 80 ° C., for 1 second to 30 minutes, alternating at a current density of 100C / dm ² ~400C / dm ² It is preferable to perform direct current electrolysis.

  The roughened aluminum substrate 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 ° C. Pickling is performed to remove dirt (smut) remaining on the surface after etching. 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 a temperature of 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 processing as described above, the method condition is not particularly limited as long as the center line average group Ra Ra of the processing surface is 0.2 to 0.5 μm.

[Anodizing treatment]
The aluminum substrate that has been roughened as described above is then anodized to form an oxide film. 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 an 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. Here, the second and third components are, for example, metal ions such as Na, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and ammonium ions. Examples include cations, nitrate ions, carbonate ions, chloride ions, phosphate ions, fluorine ions, sulfite ions, titanate ions, silicate ions, borate ions and the like, and the concentration is 0 to 10,000 ppm. May be included. There are no particular limitations on the conditions for the anodizing treatment, but the treatment is preferably performed by direct current or alternating current electrolysis at a treatment liquid temperature of 10 to 70 ° C. and a current density of 0.1 to 40 A / m ² at 30 to 500 g / liter. . The thickness of the formed anodic oxide film is in the range of 0.5 to 1.5 μm. Preferably it is the range of 0.5-1.0 micrometer.

  Furthermore, after performing these treatments, water-soluble resins such as polyvinylphosphonic acid, polymers and copolymers having sulfonic acid groups in the side chain, polyacrylic acid, water-soluble metal salts (for example, zinc borate) or Those having a primer such as a yellow dye or an amine salt are also suitable. Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A-7-159983 is covalently used.

  Other preferred examples include those in which a water-resistant hydrophilic layer is provided as a surface layer on an arbitrary support. Examples of such a surface layer include a layer composed of an inorganic pigment and a binder described in US Pat. No. 3,055,295 and JP-A-56-13168, and a hydrophilic swelling described in JP-A-9-80744. Examples thereof include a layer, a sol-gel film made of titanium oxide, polyvinyl alcohol, and silicic acid described in JP-A-8-507727. These hydrophilic treatments are performed to make the surface of the support hydrophilic, in order to prevent harmful reaction of the photopolymerizable composition provided thereon, and to improve the adhesion of the photosensitive layer. It is given for the purpose.

<2. Undercoat layer>
A water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in the side chain (JP-A-59-101651), polyacrylic acid, water-soluble as an undercoat layer on the support. A metal salt (for example, zinc borate), a yellow dye, an amine salt, or the like can be provided. Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A-7-159983 is covalently used.

Other preferred examples include an undercoat layer having an onium group described in JP-A No. 2003-021908, and a substrate provided with a water-resistant hydrophilic layer as a surface layer on an arbitrary support. As such a surface layer, for example, U.S. Pat. No. 3,055,295, a layer comprising an inorganic pigment and a binder described in JP-A-56-13168, a hydrophilic swelling layer described in JP-A-9-80744, A sol-gel film made of titanium oxide, polyvinyl alcohol, silicic acid or the like described in JP-A-8-507727 can be raised. These hydrophilic treatments are performed to make the surface of the support hydrophilic, in order to prevent harmful reactions of the photosensitive composition provided thereon, and to improve the adhesion of the photosensitive layer, etc. It is given for.
The coating amount of the undercoat layer is a dry weight, generally 0.5 to 500 mg / m ^2, preferably from 1 to 100 mg / m ^2.

<3. Photopolymerizable photosensitive layer>
The photopolymerizable composition for coating the photopolymerizable photosensitive layer of the photosensitive lithographic printing plate of the present invention comprises an addition-polymerizable compound having an ethylenically unsaturated double bond (hereinafter referred to as “ethylenically unsaturated bond”). In some cases, it may be abbreviated as “containing compound”), an alkali-soluble or swellable binder, and a photopolymerization initiator as essential components, and if necessary, various compounds such as a colorant, a plasticizer, and a thermal polymerization inhibitor. Can be used together.

(A. Compound containing ethylenically unsaturated bond)
In the present invention, as the ethylenically unsaturated bond compound, a urethane group-containing (meth) acrylate compound (ethylenically unsaturated bond-containing compound (a)) having a molecular weight of 800 or less and having no alkylene oxide moiety and a linking group are used. A (meth) acrylate compound (an ethylenically unsaturated bond-containing compound (b)) having an alkylene oxide moiety and having two ethylenically unsaturated double bonds is used in combination.

  In order to make a cured film having high sensitivity and high printing durability, a compound in which ethylenically unsaturated groups are closely packed, for example, an ethylenically unsaturated bond-containing compound (a) is considered advantageous. When this compound group is used alone, it exhibits high sensitivity and high printing durability, but there is a problem that it tends to cause deterioration in developability and stain during printing due to the external environment such as temperature and humidity during exposure. there were.

On the other hand, examples of the ethylenically unsaturated compound that improves the developability while maintaining a relatively high sensitivity include (meth) acrylates having an alkylene oxide structural unit such as the compound (b) having good developer permeability. Independently, the sensitivity was low, and the exposure dose (20 to 200 μJ / cm ² ) used in CTP and the like had a problem of low printing durability and was difficult to put into practical use.
Therefore, we have been searching for various ethylenically unsaturated compounds in order to achieve both high sensitivity and developability, but by mixing both of the above-mentioned ethylenically unsaturated bond-containing compounds, the problem is overcome, We have found that compatibility of characteristics is achieved.

(Ethylenically unsaturated bond-containing compound (a))
The ethylenically unsaturated bond-containing compound (a) is a urethane group-containing (meth) acrylate compound having a molecular weight of 800 or less and having no alkylene oxide moiety, and preferably has at least one terminal ethylenically unsaturated bond, preferably It is selected from compounds having 2 or more, more preferably 2-4. The number of urethane groups contained in the ethylenically unsaturated bond-containing compound (a) is generally 1 to 4, preferably 2 to 4.
The molecular weight of the ethylenically unsaturated bond-containing compound (a) is preferably 150 to 750.

  Preferably, an unsaturated carboxylic acid ester having a hydroxyl group, an addition reaction between an unsaturated carboxylic acid amide and a polyfunctional isocyanate, or an unsaturated carboxylic acid ester having an isocyanate group, an unsaturated carboxylic acid amide and a monofunctional or polyfunctional group It is a compound manufactured using the addition reaction with alcohol.

As such a specific example, for example, a polyisocyanate compound having two or more isocyanate groups per molecule described in JP-B-48-41708 contains a hydroxyl group represented by the following formula (1). And vinyl urethane compounds containing two or more polymerizable vinyl groups in one molecule to which the vinyl monomer to be added is added.
_{CH 2 = C (R) COOCH} 2 CH (R ') OH (1)
(However, R and R ′ represent H or CH _3. )

  Further, urethane (meth) acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765 may be mentioned.

  Particularly preferred are diisocyanates (hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, and 1,1,3-trimethyl-3-isocyanatomethyl-5-isocyanato. Cyclohexane etc.) and urethane group-containing (meth) acrylate compounds synthesized by reaction with hydroxy-containing esters (hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxyisopropyl (meth) acrylate, etc.), etc. It is done.

  Specific examples of the ethylenically unsaturated bond-containing compound (a) are shown below, but are not limited thereto.

(Ethylenically unsaturated bond-containing compound (b))
The ethylenically unsaturated bond-containing compound (b) is a (meth) acrylate compound having an alkylene oxide moiety in the linking group and two ethylenically unsaturated double bonds. That is, the group connecting two ethylenically unsaturated double bonds contains an alkylene oxide moiety.

In order to obtain a cured film with high sensitivity and high printing durability, a compound in which an ethylenically unsaturated double bond group is clogged with nectar in one molecule is considered useful from the viewpoint of improved reactivity and crosslinking density. Therefore, it is poor in stability and is liable to cause stains and developability. On the other hand, when there is only one ethylenically unsaturated double bond group in one molecule, the crosslinking efficiency is lowered, and strong film surface strength may not be obtained.
Examples of the (meth) acrylate compound having two ethylenically unsaturated bonds include a compound represented by the general formula (2).
_{CH 2 = C (R 1)} COO-R 2 - (R 2 O) m-R 2 - (R 2 O) n -R 2 OCOC (R 1) = CH 2 (2)
(R ₁ independently represents a hydrogen atom or an alkyl group, and R ₂ each independently represents an alkylene group. M and n each represents an integer of 0 or more, provided that m + n ≧ 1.)
In the formula (2), it is preferable that 10 ≧ m + n ≧ 2.
In other words, esters of various polyhydric alcohols having an ethyleneoxy group or propyleneoxy group and unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, maleic acid, etc.), various fats having an ethyleneoxy group or a propyleneoxy group And amides of an aromatic polyvalent amine compound and the unsaturated carboxylic acid.

  The molecular weight of the ethylenically unsaturated bond-containing compound (b) is preferably 200-1500, more preferably 200-1000.

An alkylene oxide part is C2-C5, for example, and can mention an ethyleneoxy structural unit, a propyleneoxy structural unit, etc.
The mass proportion of the alkylene oxide moiety in the ethylenically unsaturated bond-containing compound (b) is generally 20 to 85 mass%, preferably 30 to 70 mass%.
The ethylenically unsaturated bond-containing compound (b) preferably contains 1 to 12, more preferably 1 to 8 as the total of ethyleneoxy structural units and propyleneoxy structural units.

When the alkylene oxide site is not included, high sensitivity and high printing durability can be achieved, but the developability is lowered due to the change in the external environment, and a residual film is formed. On the other hand, when 13 or more ethyleneoxy structural units and / or propyleneoxy structural units are included, the developability is improved, but the developer permeability of not only the unexposed area but also the exposed area is increased, and the printing durability is improved. Deterioration and film verification may occur.

  Although the specific example of an ethylenically unsaturated bond containing compound (b) is given to the following, it is not limited to these.

The total amount of the ethylenically unsaturated bond-containing compounds (a) and (b) is preferably in the range of 10 to 80% by mass, more preferably 20 to 60% by mass, based on the total solid content constituting the photopolymerizable photosensitive layer. Used in.
Further, the preferable mixing ratio (a: b) of the ethylenically unsaturated bond-containing compounds (a) and (b) is preferably 9: 1 to 2: 8, more preferably 8: 2 to 4: 6 in terms of mass ratio. .

  In addition, other ethylenically unsaturated bond-containing compounds other than the ethylenically unsaturated bond-containing compounds (a) and (b) may be used in combination, but the addition amount of the other ethylenically unsaturated bond-containing compounds is: 20 mass% or less is preferable with respect to the total amount of an ethylenically unsaturated bond containing compound (a) and (b).

(B. Binder)
The binder used in the photopolymerizable composition of the present invention are alkali-soluble or swelling binder, not only functions as a film-forming agent, it is necessary to be dissolved in an alkaline developer soluble in alkaline water Alternatively, an organic polymer that is swellable is used. For example, when the water-soluble organic polymer is used as the organic polymer, water development is possible.
Examples of such an organic polymer include addition polymers having a carboxylic acid group in the side chain, such as JP-A-59-44615, JP-B-54-34327, JP-B-58-12577, JP-B-54- No. 25957, JP-A-54-92723, JP-A-59-53836, JP-A-59-71048, that is, methacrylic acid copolymer, acrylic acid copolymer, Examples thereof include an itaconic acid copolymer, a crotonic acid copolymer, a maleic acid copolymer, and a partially esterified maleic acid copolymer.

  Similarly, there is an acidic cellulose derivative having a carboxylic acid group in the side chain. In addition, those obtained by adding a cyclic acid anhydride to an addition polymer having a hydroxyl group are useful. Among these, [benzyl (meth) acrylate / (meth) acrylic acid / other addition-polymerizable vinyl monomers as required] copolymers and [allyl (meth) acrylate (meth) acrylic acid / as required Other addition polymerizable vinyl monomers] copolymers are preferred. In addition, polyvinyl pyrrolidone, polyethylene oxide, and the like are useful as the water-soluble organic polymer. In order to increase the strength of the cured film, alcohol-soluble polyamide, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. are also useful. JP-B-7-120040, JP-B7-120041, JP-B7-120042, JP-B-8-12424, JP-A-63-287944, JP-A-63-287947, JP-A1-271741 And polyurethane resins described in JP-A-11-352691 are also useful for the use of the present invention.

  These organic polymer polymers can improve the strength of the cured film by introducing a radical reactive group into the side chain. Functional groups that can undergo an addition polymerization reaction include ethylenically unsaturated bond groups, amino groups, and epoxy groups, and functional groups that can become radicals upon irradiation with light include mercapto groups, thiol groups, halogen atoms, triazine structures, and onium salt structures. Moreover, a carboxyl group, an imide group, etc. are mentioned as a polar group. As the functional group capable of undergoing the addition polymerization reaction, an ethylenically unsaturated bond group such as an acryl group, a methacryl group, an allyl group, and a styryl group is particularly preferable, and an amino group, a hydroxy group, a phosphonic acid group, a phosphoric acid group, and a carbamoyl group. A functional group selected from an isocyanate group, a ureido group, a ureylene group, a sulfonic acid group, and an ammonio group is also useful.

  Also, Japanese Patent Publication No. 7-120040, Japanese Patent Publication No. 7-120041, Japanese Patent Publication No. 7-120042, Japanese Patent Publication No. 8-12424, Japanese Patent Publication No. 63-287944, Japanese Patent Publication No. 63-287947, Japanese Patent Publication No. Hei 1 The urethane-based binder polymer containing an acid group described in each of Japanese Patent No. 271741 and Japanese Patent Application No. 10-116232 is extremely excellent in strength, and is advantageous in terms of printing durability and low exposure suitability. is there.

In order to maintain the developability of the photosensitive layer, the binder preferably has an appropriate molecular weight and acid value, and a high molecular weight polymer having a mass average molecular weight of 5000 to 300,000 and an acid value of 20 to 200 is effectively used. The These polymer binders can be mixed in an arbitrary amount in the composition of the present invention. In particular, if it is 90% by mass or less, a preferable result is given in terms of the strength of the formed image. Preferably it is 10-90 mass%, More preferably, it is 30-80 mass%.
The total amount of the ethylenically unsaturated bond-containing compounds (a) and (b) and the binder are preferably in the range of 1/9 to 9/1 by mass ratio. A more preferable range is 2/8 to 8/2, still more preferably 3/7 to 7/3.

  In particular, it is preferable that the alkali-soluble or swellable binder has an ethylenically unsaturated double bond in the structure because it can cause high sensitivity and high printing durability.

(C. Photopolymerization initiator)
Depending on the wavelength of the light source used, the photopolymerization initiator contained in the photopolymerizable photosensitive layer may be various photoinitiators known in patents, literature, etc., or a combination system of two or more photopolymerization initiators (light The starting system) can be appropriately selected and used. Specific examples are listed below, but are not limited thereto.
Various photoinitiating systems have been proposed in the case of using visible light of 400 nm or more, Ar laser, second harmonic of a semiconductor laser, and SHG-YAG laser as a light source, for example, US Pat. No. 2,850,445. Certain photoreductive dyes described in No. 1, for example, rose bengal, eosin, erythrosine, etc., or a combination of a dye and an initiator, for example, a combined initiator system of a dye and an amine (Japanese Patent Publication No. 44-20189) , Hexaarylbiimidazole, radical generator and dye combination system (Japanese Examined Patent Publication No. 45-37377), hexaarylbiimidazole and p-dialkylaminobenzylidene ketone (Japanese Examined Patent Publication No. 47-2528, Japanese Unexamined Patent Publication No. 54- 155292), a system of a cyclic cis-α-dicarbonyl compound and a dye (Japanese Patent Laid-Open No. 48-84183), Azine and merocyanine dye systems (Japanese Patent Laid-Open No. 54-151024), 3-ketocoumarin and activator systems (Japanese Patent Laid-Open Nos. 52-111261, 58-15503), biimidazole, styrene derivatives, thiols System (JP 59-140203 A), organic peroxide and dye system (JP 59-1504, JP 59-140203, JP 59-189340, JP 62-174203). No. 6, JP-B 62-1641, US Pat. No. 4,766,055), dyes and active halogen compounds (JP-A 63-258903, JP-A 2-63054, etc.), dyes and borate compounds (JP, A, etc.) JP-A-62-143044, JP-A-62-1050242, JP-A-64-13140, JP-A-64-13141, JP-A-64-13142, JP-A-64- 13143, JP-A-64-13144, JP-A-64-17048, JP-A-1-229003, JP-A-1-298348, JP-A-1-138204, etc.) Dye having a rhodanine ring and radical generator Systems (JP-A-2-17943, JP-A-2-244050), titanocene and 3-ketocoumarin dye systems (JP-A 63-221110), titanocene and xanthene dyes, addition polymerization containing amino groups or urethane groups A combination of possible ethylenically unsaturated compounds (JP-A-4-221958, JP-A-4-219756), titanocene and a specific merocyanine dye system (JP-A-6-295061), having a titanocene and a benzopyran ring And dye systems (Japanese Patent Laid-Open No. 8-3344897).

Recently, a laser having a wavelength of 400 to 410 nm (violet laser) has been developed, and a photoinitiating system exhibiting high sensitivity at a wavelength of 450 nm or less that responds to it has been developed, and these photoinitiating systems are also used.
For example, a cationic dye / borate system (JP-A-11-84647), a merocyanine dye / titanocene system (JP-A 2000-147663), a carbazole type dye / titanocene system (Japanese Patent Application No. 11-212480) and the like can be mentioned. .
In the present invention, a system using a titanocene compound is particularly preferable in view of sensitivity.

Various titanocene compounds can be used. For example, various titanocene compounds described in JP-A-59-152396 and JP-A-61-151197 can be appropriately selected and used. . More specifically, di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,3,4,5 , 6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2 , 4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2, 4-di-fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-Ti -Bis-2, - difluoro-1-yl, di - cyclopentadienyl -Ti- bis-2,6-difluoro-3- (pyrr-1-yl) - can be exemplified 1-yl and the like.

Furthermore, as required for the above photopolymerization initiator, thiol compounds such as 2-mercaptobenzthiazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, N-phenylglycine, N, N-dialkylamino aromatic alkyl ester, etc. By adding a hydrogen donating compound such as an amine compound, the photoinitiating ability can be further enhanced.
The amount of the photopolymerization initiator (system) used is generally 0.05 to 100 parts by weight, preferably 0.1 to 70 parts by weight, more preferably 100 parts by weight of the ethylenically unsaturated bond-containing compound. It is used in the range of 0.2 to 50 parts by mass.

  The photosensitive lithographic printing plate of the present invention is particularly effective in a photopolymerizable photosensitive layer having a photosensitive wavelength in the range of 350 to 450 nm. Examples of the photopolymerization initiator (system) having a photosensitive wavelength in the range of 350 nm to 450 nm include a composite initiator system of a sensitizing dye having a maximum absorption at 350 to 400 nm and an active initiator as described above. .

  In the present invention, in addition to the basic components described above, a small amount is used to prevent unnecessary thermal polymerization of the ethylenically unsaturated bond-containing compound that can be polymerized during the production or storage of the photopolymerizable composition used in the photosensitive layer. It is desirable to add a thermal polymerization inhibitor. Suitable thermal polymerization inhibitors include haloid quinone, 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-t-butylphenol), N-nitrosophenylhydroxylamine cerium salt, N-nitrosophenylhydroxylamine aluminum 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 total solid content of the composition. If necessary, a higher fatty acid derivative such as behenic acid or behenamide is added to prevent polymerization inhibition by oxygen, and it is unevenly distributed on the surface of the photopolymerizable photosensitive layer in the process of drying after coating. May be. The addition amount of the higher fatty acid derivative or the like is preferably about 0.5 mass% to about 10 mass% of the total solid content of the composition.

  Further, a colorant may be added for the purpose of coloring the photopolymerizable photosensitive layer. Examples of the colorant include phthalocyanine pigments (CIPigment Blue 15: 3, 15: 4, 15: 6, etc.), azo pigments, pigments such as carbon black and titanium oxide, ethyl violet, crystal violet, azo dyes, There are anthraquinone dyes and cyanine dyes. The addition amount of the dye and the pigment is preferably about 0.5% by mass to about 20% by mass of the total composition. In addition, in order to improve the physical properties of the cured film, an additive such as an inorganic filler or a plasticizer such as dioctyl phthalate, dimethyl phthalate, or tricresyl phosphate may be added. These addition amounts are preferably 10% by mass or less of the total solid content (total composition) of the composition.

  When applying the photopolymerizable composition, it is dissolved in various organic solvents and used. 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, di 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 are ethyl and the like. These solvents can be used alone or in combination. And the density | concentration of the solid content in a coating solution is 1-50 mass% generally.

A surfactant can be added to the photopolymerizable composition in order to improve the coating surface quality. The coating amount of the mass after drying, preferably about 0.1 g / m ² ~ about 10 g / m ^2, more preferably 0.3 to 5 g / m ^2, more preferably 0.5 to 3 g / m ² .

<4. Protective layer>
In the photosensitive lithographic printing plate of the present invention, since exposure is usually performed in the air, it is preferable to further provide a protective layer on the layer of the photopolymerizable composition. 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 for the protective layer has been conventionally devised, which is described in detail in US Pat. No. 3,458,311 and JP-A-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, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC made by Kuraray Co., Ltd. , 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. In addition, 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 polymer layer, film peeling due to insufficient adhesion tends 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, in a hydrophilic polymer mainly composed of polyvinyl alcohol, an acrylic emulsion or a water-insoluble vinyl pyrrolidone-vinyl acetate copolymer is mixed in an amount of 5 to 80% by mass and laminated on the polymerization layer. It is described that adhesiveness can be obtained. 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-A-55-49729.

  Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (such as a water-soluble dye) that is excellent in the transmission of light from 350 nm to 450 nm and that can absorb light of 500 nm or more, which is used for exposure, it is safe light without causing a decrease in sensitivity. The aptitude can be further enhanced.

The coating amount of the protective layer is generally about 0.1 g / m ² to about 15 g / m ² , preferably 1.0 g / m ² to about 5.0 g / m ² in terms of the mass after drying.

<5. Plate making method>
The photosensitive lithographic printing plate of the present invention is usually subjected to image exposure, and then an unexposed portion of the photosensitive layer is removed with a developer to obtain an image.

  In addition, as the plate making process of the photosensitive lithographic printing plate of the present invention, the entire surface may be heated before exposure, during exposure, and between exposure and development as necessary. By such heating, an image forming reaction in the photosensitive layer is promoted, and advantages such as improvement in sensitivity and printing durability and stabilization of sensitivity may occur. Further, for the purpose of improving the image strength and printing durability, it is also effective to subject the developed image to full post heating or full exposure. Usually, the heating before development is preferably performed under a mild condition of 150 ° C. or less. If the temperature is too high, problems such as covering up to the non-image area occur. Very strong conditions are used for heating after development. Usually, it is the range of 200-500 degreeC. If the temperature is low, sufficient image strengthening action cannot be obtained. If the temperature is too high, problems such as deterioration of the support and thermal decomposition of the image area occur.

  As a method for exposing a photosensitive lithographic printing plate according to the present invention, a known method can be used without limitation. Desirably, the wavelength of the light source is 350 nm to 450 nm, and specifically, an InGaN-based semiconductor laser is suitable. The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like. The photosensitive layer component of the present invention can be made soluble in neutral water or weak alkaline water by using a highly water-soluble component. A lithographic printing plate having such a structure is used in a printing machine. After loading on top, exposure-development can be performed on the machine.

Further, as other exposure light rays for the photopolymerizable composition according to the present invention, ultrahigh pressure, high pressure, medium pressure, and low pressure mercury lamps, chemical lamps, carbon arc lamps, xenon lamps, metal halide lamps, various visible and ultraviolet lasers. A lamp, a fluorescent lamp, a tungsten lamp, sunlight, etc. can also be used. As available laser light sources of 350 nm to 450 nm, the following can be used.
As a gas laser, Ar ion laser (364 nm, 351 nm, 10 mW to 1 W), Kr ion laser (356 nm, 351 nm, 10 mW to 1 W), He—Cd laser (441 nm, 325 nm, 1 mW to 100 mW), and solid laser as Nd: YAG (YVO ₄ ) and SHG crystal × 2 combinations (355 nm, 5 mW to 1 W), Cr: LiSAF and SHG crystal combination (430 nm, 10 mW), KNbO ₃ ring resonator (430 nm, 30 mW) as a semiconductor laser system A combination of a waveguide type wavelength conversion element and AlGaAs, InGaAs semiconductor (380 nm to 450 nm, 5 mW to 100 mW), a combination of a waveguide type wavelength conversion element, AlGaInP and AlGaAs semiconductor (300 nm to 350 nm, 5 mW to 10 mW) 0 mW), AlGaInN (350 nm to 450 nm, 5 mW to 30 mW), and other pulse lasers include N ₂ laser (337 nm, pulse 0.1 to 10 mJ) and XeF (351 nm, pulse 10 to 250 mJ). In particular, an AlGaInN semiconductor laser (commercially available InGaN-based semiconductor laser 400 to 410 nm, 5 to 30 mW) is preferable in terms of wavelength characteristics and cost.

  Further, as the lithographic printing plate exposure apparatus of the scanning exposure method, there are an inner drum method, an outer drum method, and a flat bed method as an exposure mechanism, and a light source that can continuously oscillate among the light sources can be preferably used. . Practically, the following exposure apparatus is particularly preferable in terms of the relationship between the photosensitive material sensitivity and the plate making time.

Single-beam to triple-beam exposure equipment that uses one or more gas lasers or solid-state laser light sources, so that the internal drum system produces a semiconductor laser with a total output of 20 mW or more; Multi-beam (1 to 10) exposure equipment using one or more semiconductor lasers, gas lasers or solid-state lasers; one semiconductor laser, gas laser or solid-state laser so that the total output is 20 mW or more with the external drum system Multi-beam (1 to 9) exposure apparatus used above; Multi-beam (10 or more) exposure apparatus using one or more semiconductor lasers or solid-state lasers so that the total output is 20 mW or more in the external drum system. In the laser direct-drawing lithographic printing plate as described above, the photosensitive material sensitivity X (J / cm ² ), the photosensitive material exposure area S (cm ² ), the power q (W) of one laser light source, the laser Equation (eq 1) holds between the number n and the total exposure time t (s).
X · S = n · q · t-(eq 1)
i) In the case of the internal drum (single beam) system, the laser rotation speed f (radians / s), the sub-scanning length Lx (cm) of the photosensitive material, the resolution Z (dots / cm), and the total exposure time t (s) In general, equation (eq 2) holds.
f.Z.t = Lx-(eq 2)

ii) In the case of the external drum (multi-beam) system, the drum rotation speed F (radians / s), the photosensitive material sub-scanning length Lx (cm), the resolution Z (dots / cm), the total exposure time t (s), the number of beams In general, the equation (eq 3) is established during (n).
f.Z.n.t = Lx-(eq 3)

iii) In the case of the flat head (multi-beam) method, the rotational speed H (radians / s) of the polygon mirror, the sub-scanning length Lx (cm) of the photosensitive material, the resolution Z (dots / cm), the total exposure time t (s), Equation (eq 4) is generally established between the number of beams (n).
f.Z.n.t = Lx-(eq 4)

Resolution (2560 dpi) required for an actual printing plate, plate size (A1 / B1, sub-scanning length 42 inch), exposure conditions of about 20 sheets / hour and photosensitive characteristics of the photosensitive composition of the present invention (photosensitive wavelength, By substituting (sensitivity: about 0.1 mJ / cm ² ) into the above equation, it can be understood that a combination with a multi-beam exposure method using a laser having a total output of 20 mW or more is preferable in the photosensitive material of the present invention. However, when a laser having a necessary and sufficient output (30 mW or more) is used, a combination with an internal drum type semiconductor laser single beam exposure apparatus is most preferable in terms of operability and cost.

Further, after image exposure by a known active light, until development, providing a 1 second at a temperature of 50 ° C. to 150 DEG ° C. for the purpose of increasing the curing rate of the photopolymerizable photosensitive layer of 5 minute time heating process Thus, the curability of the non-image area can be improved and the printing durability can be further improved, which is more preferable.

  Further, the developed photosensitive lithographic printing plate is washed with water, a surfactant, etc. as described in JP-A Nos. 54-8002, 55-1115045, 59-58431, etc. And a desensitizing solution containing gum arabic, starch derivatives and the like. These treatments can be used in various combinations for the post-treatment of the photosensitive lithographic printing plate of the present invention. The lithographic printing plate obtained by such treatment is applied to an offset printing machine and used for printing a large number of sheets.

  The above-mentioned photosensitive lithographic printing plate can be developed using a conventionally known developer to form an image. These conventionally known developers are described in JP-B-57-7427. Developers such as sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic ammonium phosphate, dibasic phosphate Aqueous solutions of inorganic alkaline agents such as ammonium, sodium metasilicate, sodium bicarbonate, aqueous ammonia, and organic alkaline agents such as monoethanolamine or diethanolamine are suitable. The alkali solute concentration of the developer is generally 0.1 to 10% by mass, preferably 0.5 to 5% by mass.

  Such an alkali developer may contain a small amount of an organic solvent such as a surfactant, benzyl alcohol, 2-phenoxyethanol, and 2-butoxyethanol as necessary. Examples thereof include those described in US Pat. Nos. 3,375,171 and 3,615,480. Furthermore, the developing solution described in each gazette of Unexamined-Japanese-Patent No. 50-26601, 58-54341, Japanese Patent Publication No. 56-39464, and 56-42860 can also be mentioned.

  The developer used for the plate making of the photosensitive lithographic printing plate of the present invention is a nonionic interface having a polyoxyalkylene ether group from the point of deterioration of dots such as halftone dots and solid fine lines as described above. An alkaline developer containing an activator and having a pH of 10.5 to 13.5 (more preferably pH 1.0 to 12.5) is preferred.

  By containing a nonionic surfactant having a polyoxyalkylene ether group, dissolution of the photosensitive layer in the unexposed area can be promoted and the permeability of the developer into the exposed area can be reduced. As the surfactant containing a polyoxyalkylene ether group, one having a structure of the following general formula (A) is preferably used.

R ³ —O— (R ⁴ —O) qH (A)
In the formula, R ³ has an optionally substituted alkyl group having 3 to 15 carbon atoms, an optionally substituted aromatic hydrocarbon group having 6 to 15 carbon atoms, or a substituent. A heteroaromatic cyclic group having 4 to 15 carbon atoms (wherein the substituent is an alkyl group having 1 to 20 carbon atoms, a halogen atom such as Br, Cl, or I, or an aromatic hydrocarbon having 6 to 15 carbon atoms) Group, an aralkyl group having 7 to 17 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, and an acyl group having 2 to 15 carbon atoms), and R ⁴ is C1-C100 alkylene group which may have a substituent (In addition, as a substituent, a C1-C20 alkyl group and a C6-C15 aromatic hydrocarbon group are mentioned.). Q represents an integer of 1 to 100.

  In the definition of the above formula (A), specific examples of the “aromatic hydrocarbon group” include phenyl group, tolyl group, naphthyl group, anthryl group, biphenyl group, phenanthryl group and the like, and “heteroaromatic ring” Specific examples of the “group” include furyl group, thionyl group, oxazolyl group, imidazolyl group, pyranyl group, pyridinyl group, acridinyl group, benzofuranyl group, benzothionyl group, benzopyranyl group, benzooxazolyl group, benzoimidazolyl group, and the like. It is done.

In addition, the (R ⁴ —O) q portion of the formula (A) may be two or three groups within the above range. Specific examples include random or block combinations of ethyleneoxy and propyleneoxy groups, ethyleneoxy and isopropyloxy groups, ethyleneoxy and butyleneoxy groups, ethyleneoxy groups and isobutylene groups, and the like. . In the present invention, the surfactant having a polyoxyalkylene ether group is used alone or in combination, and it is effective to add 1 to 30% by mass, preferably 2 to 20% by mass in the developer. If the addition amount is small, the developability is deteriorated. On the other hand, if the amount is too large, the development damage becomes strong and the printing durability of the printing plate is lowered.

  Examples of the nonionic surfactant having a polyoxyalkylene ether group represented by the above formula (A) include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether. Polyoxyethylene aryl ethers such as polyoxyethylene phenyl ether and polyoxyethylene naphthyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene methyl phenyl ether, polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether Kind.

  Further, other surfactants described below may be added. Other surfactants include polyoxyethylene alkyl esters such as polyoxyethylene stearate, sorbitan monolaurate, sorbitan monostearate, sorbitan distearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate Nonionic surfactants such as sorbitan alkyl esters such as glycerol monostearate and monoglyceride alkyl esters such as glycerol monooleate; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; sodium butylnaphthalenesulfonate; pentylnaphthalenesulfonic acid Alkylnaphthalenesulfonic acid such as sodium, sodium hexylnaphthalenesulfonate, sodium octylnaphthalenesulfonate , Alkyl sulfates such as sodium lauryl sulfate, alkyl sulfonates such as sodium dodecyl sulfonate, sulfosuccinic acid ester salts such as sodium dilauryl sulfosuccinate; alkyl betaines such as lauryl betaine and stearyl betaine Amphoteric surfactants such as amino acids can be used, and anionic surfactants such as alkylnaphthalene sulfonates are particularly preferred.

  Surfactants can be used alone or in combination. Further, the content of the surfactant in the developer is preferably in the range of 0.1 to 20% by mass in terms of active ingredient.

  This alkali developer usually contains an inorganic alkali salt. The inorganic alkali salt can be appropriately selected. For example, sodium hydroxide, potassium, ammonium, lithium, sodium silicate, potassium, ammonium, lithium, tribasic sodium phosphate, potassium, ammonium Inorganic alkaline agents such as sodium carbonate, potassium, ammonium, sodium hydrogencarbonate, potassium, ammonium, sodium borate, potassium, and ammonium. These may be used alone or in combination of two or more.

In the case of using silicate, developability is achieved by adjusting the mixing ratio and concentration of silicon oxide SiO ₂ which is a component of silicate and alkali oxide M ₂ O (M represents an alkali metal or ammonium group). Can be easily adjusted. Among the alkaline aqueous solutions, those having a mixing ratio (SiO ₂ / M ₂ O: molar ratio) of the silicon oxide SiO ₂ and the oxide M ₂ O of 0.5 to 3.0 are preferable and 1.0 to 1.0. Those of 2.0 are preferred. When the SiO ₂ / M ₂ O is less than 0.5, it is preferably 1 to 10% by mass, more preferably 3 to 8% by mass, and most preferably 4 to 7% by mass with respect to the mass of the alkaline aqueous solution. If this concentration is less than 1% by mass, developability and processing ability may be lowered. If it exceeds 10% by mass, precipitation and crystals are likely to be generated, and further gelation tends to occur during neutralization in the waste liquid. Therefore, the waste liquid treatment may be hindered.

  In addition, an organic alkali agent may be supplementarily used for the purpose of finely adjusting the alkali concentration and assisting the solubility of the photosensitive layer. Examples of the organic alkali agent include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, Examples thereof include diisopropanolamine, ethyleneimine, ethylenediamine, pyridine, tetramethylammonium hydroxide and the like. These alkali agents are used alone or in combination of two or more.

  Moreover, it is preferable that the electrical conductivity of the developing solution used by this invention is 3-30 mS / cm. If it is lower than normal, the elution of the photosensitive composition on the surface of the aluminum plate support becomes difficult, and printing is accompanied by smudges. This is because the film is delayed and a remaining film may be formed in the unexposed area. Particularly preferred conductivity is in the range of 5-20 mS / cm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.

[Examples 1-5 and Comparative Examples 3-4]
(Method for making aluminum support)
An aluminum plate having a thickness of 0.3 mm was etched by being immersed in 10% by mass sodium hydroxide at 60 ° C. for 25 seconds, washed with running water, neutralized with 20% by mass nitric acid, and then washed with water. This was subjected to an electrolytic surface roughening treatment in a 1% by mass nitric acid aqueous solution using a sinusoidal alternating waveform current at an anode time electricity of 300 coulomb / dm ² . Subsequently, after dipping in a 1% by mass aqueous sodium hydroxide solution at 40 ° C. for 5 seconds and then in a 30% by mass sulfuric acid aqueous solution and desmutting at 60 ° C. for 40 seconds, the current density in a 20% by mass sulfuric acid aqueous solution was 2A / current density. At dm ² , the anodization treatment was performed for 2 minutes so that the thickness of the anodized film was 2.7 g / m ² . When the surface roughness was measured, it was 0.3 μm (Ra display according to JIS B0601).

(Coating undercoat layer)
Next, an undercoat layer coating solution of the following composition was applied to the aluminum support with a wire bar, and dried at 90 ° C. for 30 seconds using a hot air dryer. The coating amount after drying was 10 mg / m ² .

(Coating liquid for undercoat layer coating)
Ethyl methacrylate and 2-acrylamido-2-methyl-1-
Propanesulfonic acid sodium salt copolymer with a molar ratio of 75:25 (molecular weight 18,000) 0.1 g
2-Aminoethylphosphonic acid 0.1g
50g of methanol
Ion exchange water 50g

(Coating of photosensitive layer)
A photosensitive solution having the following composition was prepared on the undercoat layer, applied with a wheeler so that the film thickness after drying was 1.5 g / m ^2, and dried at 120 ° C. for 2 minutes.

(Photosensitive layer coating solution (photopolymerizable composition))
Urethane resin (the following structure) (molecular weight 70,000) 1.5g
Ethylenically unsaturated bond-containing compound: Compounds listed in Table 1 and amounts added

  Sensitizing dye: 0.1 g of the following structure

  Polymerization initiator: 0.15 g of the following structure

  Sensitization aid: 0.2 g of the following structure

Colored pigment dispersion: 1.5 g of the following composition
Thermal polymerization inhibitor: N-nitrosophenylhydroxylamine 0.01 g
Surfactant: Dai Nippon Ink Chemical Co., Ltd. MegaFuck F780 0.02g
Methyl ethyl ketone 20.0g
Propylene glycol monomethyl ether 20.0g

Composition of colored pigment dispersion Pigment Blue 15: 6 15 g
10 g of allyl methacrylate / methacrylic acid copolymer
(Copolymerization molar ratio 83/17) Thermal polymerization Cyclohexanone 15g
Methoxypropyl acetate 20g
Propylene glycol monomethyl ether 40g

(Coating of protective layer)
A protective layer coating solution having the following composition was coated on the photosensitive layer so that the dry coating mass was 2 g / m ² and dried at 100 ° C. for 2 minutes.
(Coating solution composition for protective layer)
4 g of polyvinyl alcohol (degree of saponification 98 mol%, degree of polymerization 550)
Polyvinylpyrrolidone (molecular weight 100,000) 1g
95g of water

The photosensitive lithographic printing plate obtained above was made by the following method and evaluated for sensitivity and printing durability.
(exposure)
For Examples 1 to 5 and Comparative Examples 1 and 2, the amount of light on the plate surface was adjusted to 0.05 mJ / cm ² with an internal drum type experimental machine equipped with a 30 mW violet laser (405 nm). The gray scale is pasted on the plate surface and exposed from above (the gray scale is made so that the light quantity changes by 1 / √2; the higher the gray scale level, the higher the sensitivity. ).
For comparison of soiling properties, the unexposed lithographic printing plate precursor was left undisturbed in an environment of 25 ° C. and 50% RH for 1 hour. Then, after packing with aluminum craft and storing at 60 ° C. for 3 days, exposure was performed by the method described above.

(Development / plate making)
Fuji Photo Film Co., Ltd. automatic processor LP-850P2 (preheat temperature is 100 ° C.) was charged with the following developer and Fuji Photo Film Co., Ltd. finisher FP-2W, each with a developer temperature of 30 ° C. and a development time of 18 seconds. The plate exposed under the conditions was developed / plate making to obtain a lithographic printing plate.

(PH 11.6 aqueous solution having the following composition)
Sodium hydroxide 0.15 parts by mass The following structural compound 5.0 parts by mass Ethylenediaminetetraacetic acid / 4Na salt 0.1 parts by mass Water 94.75 parts by mass

The sensitivity measurement was performed under the above conditions.
The printing durability was determined by examining the number of printed sheets in which a solid image produced under the above conditions was worn away in the printing process and no ink was applied. The stain resistance was evaluated by using a plate that had been stored at 60 ° C. for 3 days, and the stain resistance during printing was evaluated. In the following evaluation results, ○: good, Δ: slightly inferior, ×: inferior. The printer used was an R201 type printer manufactured by Man Roland, and the ink used was GEOS G black (N) manufactured by Dainippon Ink.
The evaluation results are shown in Table 1.

  From Table 1, it was clarified that the examples of the present invention have higher sensitivity and higher printing durability than the comparative examples, while maintaining developability and excellent stain resistance during printing.

[Examples 6 to 10 and Comparative Examples 5 to 8]
(Method for making aluminum support)
An aluminum plate of material 1S having a thickness of 0.30 mm was used with a No. 8 nylon brush and an 800 mesh Bamiston water suspension, and the surface was grained and washed thoroughly with water. Etching was performed by immersing in 10% sodium hydroxide at 70 ° C. for 60 seconds, washing with running water, neutralizing and washing with 20% HNO ₃ , and washing with water. This was subjected to an electrolytic surface roughening treatment in a 1% nitric acid aqueous solution with a anodic electricity quantity of 300 coulomb / dm ² using a sinusoidal alternating current under the condition of V _A = 12.7V. When the surface roughness was measured, it was 0.45 μm (Ra indication). Subsequently, after dipping in 30% H ₂ SO ₄ aqueous solution and desmutting at 55 ° C. for 2 minutes, a cathode was placed on the grained surface in 33 ° C. and 20% H ₂ SO ₄ aqueous solution to obtain a current density. When anodized at 5 A / dm ² for 50 seconds, the thickness was 2.7 g / m ² .

(Coating undercoat layer)
Next, an undercoat layer coating solution of the following composition was applied to the aluminum support with a wire bar, and dried at 90 ° C. for 30 seconds using a hot air dryer. The coating amount after drying was 10 mg / m ² .

(Coating liquid for undercoat layer coating)
90g of methanol
10g of pure water
0.01g of the following structural compound

(Coating of photosensitive layer)
A photosensitive solution having the following composition was prepared on the undercoat layer, applied with a wheeler so that the film thickness after drying was 1.5 g / m ^2, and dried at 120 ° C. for 2 minutes.

(Photosensitive layer coating solution (photopolymerizable composition))
Urethane resin (the following structure) 1.5g
Ethylenically unsaturated bond-containing compound: Compounds listed in Table 2 and amounts added

Sensitizing dye: 0.1 g of the following structure

Polymerization initiator: 2,2′-bis (2-chlorophenyl) -4, 4 ′, 5,5′-tetraphenyl-1,2-bisimidazole 0.15 g
Sensitization aid: 0.2 g of 2-mercaptobenzimidazole
Colored pigment dispersion: 1.5 g of the following composition
Thermal polymerization inhibitor: N-nitrosophenylhydroxylamine 0.01 g
Surfactant: Dai Nippon Ink Chemical Co., Ltd. MegaFuck F780 0.02g
Methyl ethyl ketone 20.0g
Propylene glycol monomethyl ether 20.0g

(Composition of colored pigment dispersion)
Pigment Blue 15: 6 15g
10 g of allyl methacrylate / methacrylic acid copolymer
(Copolymerization molar ratio 83/17) Thermal polymerization Cyclohexanone 15g
Methoxypropyl acetate 20g
Propylene glycol monomethyl ether 40g

  Coating of the protective layer, plate making and evaluation were carried out in the same manner as in Example 1. The results are shown in Table 2.

  As in Table 1, also in Table 2, it is clear that the examples of the present invention have high sensitivity and high printing durability while maintaining developability and no smearing during printing, as compared with Comparative Examples. It was.

Claims (3)

  In a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer containing an addition-polymerizable compound having an ethylenically unsaturated double bond, an alkali-soluble or swellable binder, and a photopolymerization initiator on a support, The photopolymerizable photosensitive layer is an addition-polymerizable compound having an ethylenically unsaturated double bond (a) a urethane group-containing (meth) acrylate compound having a molecular weight of 800 or less and having no alkylene oxide moiety, and (B) A photosensitive lithographic printing plate comprising a (meth) acrylate compound having an alkylene oxide moiety in a linking group and having two ethylenically unsaturated double bonds.   The photosensitive lithographic printing plate according to claim 1, wherein the photosensitive wavelength of the photopolymerizable photosensitive layer is in the range of 350 nm to 450 nm.   (A) a urethane group-containing (meth) acrylate compound having a molecular weight of 800 or less and having no alkylene oxide moiety, and (b) an alkylene oxide moiety in the linking group and two ethylenically unsaturated double bonds. 2. The photosensitive lithographic printing plate according to claim 1, wherein the mass ratio of the (meth) acrylate compound is in the range of 9: 1 to 2: 8 as the compound (a) :( b).