JPH10282664A - Production of negative type planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process capable of stably and easily producing a plate material for a negative type planographic printing plate which is directly formable from digital data of a computer, etc., and has excellent stability in preservation and high sensitivity by recording the use of a solid laser for radiating IR rays and semiconductor laser. SOLUTION: The production of the negative paleographic printing plate including a stage of applying a photosensitive layer coating material contg. a novolak resin, acid generating agent, acid crosslinkable compd. and IR absorbent on a base is executed in this process. In such a case, the pH of the coating liquid is adjusted to a range of 3 to 7 in preparing the coating liquid. The pH of the coating liquid refers to the value obtd. by adding 10 wt.% pure water to the coating liquid and measuring the pH with an ordinary glass pH electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an image recording material which can be used as a lithographic printing plate material, and more particularly to a so-called lithographic plate capable of directly making a plate by using an infrared laser from a digital signal of a computer or the like. The present invention relates to a method for manufacturing a printing plate material.

[0002]

2. Description of the Related Art Conventionally, as a system for making a plate directly from digital data of a computer, an electrophotographic system, a photopolymerization system for exposing using a laser emitting blue or green light, and a silver salt on a photosensitive resin are known. Laminated ones, silver salt diffusion transfer methods, and the like have been proposed. However, in the case of using the electrophotographic method, an image forming process such as charging, exposure, and development is complicated, and the apparatus is complicated and large. In the photopolymerization system, since the plate material is highly sensitive to blue or green light, it is difficult to handle in a bright room. In the methods (1) and (2), processing such as development is complicated since a silver salt is used, and furthermore, there is a disadvantage that silver is contained in the processing waste liquid.

On the other hand, the development of lasers in recent years has been remarkable, and in particular, solid-state lasers and semiconductor lasers that emit infrared light having a wavelength of 760 nm to 1200 nm have become easily available in high power and small size. These lasers are very useful as a recording light source when making a plate directly from digital data of a computer or the like. However, many photosensitive recording materials that are practically useful have a photosensitive wavelength of 760 nm.
Because of the following visible light range, these infrared lasers cannot record images. Therefore, a material that can be recorded by an infrared laser is desired.

[0004] As such a recording material recordable with an infrared laser, a heat-sensitive recording material containing a resol type phenol resin and carbon black disclosed in JP-A-56-69193, and JP-A-7-20629. And a recording material comprising an onium salt, a resol resin, a novolak resin, and an infrared absorber. Also,
JP-A-7-271029 describes a recording material comprising a haloalkyl-substituted s-triazine, a resole resin, a novolak resin, and an infrared absorber. In these recording materials, crosslinking is caused by heating in the presence of an acid generated by image exposure to form an image, and an optimal combination of a resin, a crosslinking agent, an acid generator, and the like constituting a photosensitive layer is optimal. Is being considered. However, even if the recording material is prepared by preparing a suitable combination of photosensitive layer coating solutions, the compounded coating solution is easily affected by the pH and drying temperature of the system at the time of coating and drying. Has been found to be unstable, for example, when scaled up and manufactured on an industrial scale, unexpected decrease in sensitivity and unevenness of the photosensitive layer may occur.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make a plate directly from digital data of a computer or the like by recording using a solid-state laser and a semiconductor laser that emit infrared light, and furthermore, it is possible to obtain a stable image when storing. It is an object of the present invention to provide a production method capable of stably and easily producing a negative type lithographic printing plate material having excellent properties and high sensitivity even on an industrial scale.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a negative lithographic printing material containing a novolak resin, an acid generator, an acid-crosslinkable compound, and an infrared absorber.
Was adjusted in the range of 3-7. The image formation using the negative type image recording material of the present invention is based on the following chain mechanism. That is, the infrared absorbent,
(1) Absorb infrared laser to generate heat, (2) Next,
Due to this heat, a compound that generates an acid by the action of heat generates an acid, and (3) a compound having a property of being cross-linked by the generated acid is cross-linked to form a negative image. According to the present invention, a recording material that can be directly made by an infrared laser is obtained by the mechanism described above. When preparing a coating solution for the photosensitive layer, the pH is adjusted to a range of 3 to 7, Crosslinking reaction of each component in the coating solution,
Prevention of undesired reactions such as decomposition and invalidation of generated acid improves storage stability, and the characteristics of various compounded compounds even under scaled-up conditions and when applying coating solutions after storage Without compromising
It is presumed that a method for producing a negative type lithographic printing plate material having high sensitivity stably can be produced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The method for producing a negative lithographic printing material of the present invention comprises a step of preparing a coating solution for a photosensitive layer containing a novolak resin, an acid generator, an acid crosslinking compound, and an infrared absorber (hereinafter, appropriately referred to as a coating solution), The method includes a step of applying a photosensitive coating solution to a support. In the step of preparing the photosensitive layer coating solution, the pH is adjusted to a range of 3 to 7. Each component of the coating solution, that is, a novolak resin, an acid generator, an acid crosslinkable compound, an infrared absorber and other optional components are blended by a conventional method, and then the pH is adjusted.
Is preferably adjusted to a predetermined range. In addition, since the photosensitive layer coating solution of the present invention contains a resin component and the like, and it is difficult to measure the pH, the pH of the coating solution in the present invention is defined as 10% by weight of pure water added to the coating solution, It refers to the value measured with a pH electrode. Accordingly, hereinafter, the pH in the present invention refers to a value measured under these conditions unless otherwise specified. The coating solution needs to have a pH of 3 to 7, and from the viewpoint of the sensitivity of the obtained photosensitive layer, the pH is preferably 3 to 5. When the pH of the coating solution is less than 3,
Developing defects are likely to occur, which is not preferable. Further, when an infrared absorbing dye which is relatively weak to acid is used as a compounding component, usable components are limited, for example, the infrared absorbing dye may be decomposed to cause a decrease in sensitivity. Further, when the pH of the coating solution exceeds 7, the sensitivity is also lowered, and both are not preferable.

The adjustment of the pH of the coating solution in the method of the present invention is effective in producing a negative lithographic printing material containing a novolak resin, an acid generator, an acid-crosslinkable compound and an infrared absorber. This is particularly effective when a methylol compound is used as the compound. Examples of the methylol-based compound include a resole resin and a low molecular weight methylol compound. A particularly effective example is a case where an aromatic compound and a heterocyclic compound poly-substituted with an alkoxymethyl group are used as a crosslinking agent.

The pH of the coating solution can be adjusted by any method. For example, (a) a method of adding an acidic or basic substance soluble in the coating solution to the prepared coating solution,
(b) The components of the coating solution are previously selected and set so that the solution becomes neutral to weakly acidic, and the pH of the prepared coating solution itself is adjusted to 3 to 7
And (c) adjusting the pH to 3 to 7 by assembling a buffer solution system.

Specifically, for example, in the method (a), after measuring the pH of the prepared coating solution by a predetermined method,
Consider the type and amount of the acidic substance and the basic substance to be added according to the measured value, gradually add the coating liquid with stirring, then collect a sample and add 10% by weight of pure water to adjust the pH. It is preferable to confirm that it is in the range of 3 to 7. As the acidic substance and the basic substance that can be used here, a substance that does not affect the compound in the coating solution may be selected.
Commonly used acidic and basic substances include p
-Organic acids such as toluenesulfonic acid, benzenesulfonic acid, and methanesulfonic acid; inorganic acids such as sulfuric acid and hydrochloric acid; organic bases such as triethylamine and pyridine; and salts such as triethylamine salt of p-toluenesulfonic acid. . In the method (b), the pH of each compound solution of the coating solution components to be used may be measured in advance, and the balance with the compounding amount may be examined, and the solutions of all the coating solution components are neutral to weakly acidic. Selecting the one is the easiest way.
The method of assembling the buffer solution system of (c) specifically uses a combination of tris (hydroxymethyl) and hydrochloric acid, "Anal. Chem. Vol. 28, No. 1322.
(1956) ".
And the like.

Next, a negative type lithographic printing material to which the production method of the present invention can be applied (hereinafter referred to as a lithographic printing material as appropriate).
Each component will be described. [Infrared absorber] The infrared absorber used in the negative type lithographic printing material according to the present invention refers to a compound that absorbs infrared rays and generates heat, and specifically, has a wavelength of 760 nm to 1200.
dyes or pigments that effectively absorb infrared rays of 10 nm, preferably dyes or pigments having an absorption maximum at a wavelength of 760 nm to 1200 nm. As the dye, commercially available dyes and known dyes described in literatures such as "Dye Handbook" (edited by The Society of Synthetic Organic Chemistry, Japan, 1970) can be used. Specifically, azo dyes, metal complex salt azo dyes,
Dyes such as a pyrazolone azo dye, an anthraquinone dye, a phthalocyanine dye, a carbonium dye, a quinone imine dye, a methine dye, a cyanine dye, and a metal thiolate complex are exemplified. Preferred dyes include, for example, those described in
Cyanine dyes described in JP-A-8-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, etc .;
No. 96, JP-A-58-181690, JP-A-58-1
No. 94595, etc., methine dyes described in
8-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996,
Naphthoquinone dyes described in JP-A-60-52940 and JP-A-60-63744;
Squarylium dyes described in No. 12792, etc.,
Cyanine dyes described in British Patent No. 434,875 and the like can be mentioned. No. 5,156,93.
The near-infrared absorption sensitizer described in No. 8 is also preferably used, and substituted arylbenzo (thio) pyrylium salts described in U.S. Pat. No. 3,881,924;
No. 42645 (U.S. Pat. No. 4,327,169), a trimethinethiapyrylium salt described in JP-A-58-1810.
No. 51, No. 58-220143, No. 59-41363
Nos. 59-84248, 59-84249, 59-146063, and 59-146061 and pyrylium compounds described in JP-A-59-2161.
No. 46, a cyanine dye disclosed in U.S. Pat. No. 4,283,4.
No. 75 pentamethine thiopyrylium salt and the pyrylium compounds disclosed in JP-B-5-13514 and JP-A-5-19702 are also preferably used. Another preferred example of the dye is disclosed in U.S. Pat.
No. 3 includes near infrared absorbing dyes described as formulas (I) and (II). Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and nickel thiolate complexes.

The pigments used here include commercially available pigments and color index (CI) handbook, "Latest Pigment Handbook" (edited by Japan Pigment Technical Association, 1977),
"Latest Pigment Application Technology" (CMC Publishing, 1986),
Pigments described in "Printing Ink Technology" (CMC Publishing, 1984) having absorption in the infrared to near infrared region can be used. The types of pigments include black pigment, yellow pigment, orange pigment, brown pigment, red pigment, purple pigment,
Blue pigment, green pigment, fluorescent pigment, metal powder pigment, etc.
Polymer-bound dyes. Specifically, insoluble azo pigments, azo lake pigments, condensation azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments,
Perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, dyeing lake pigments,
Azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black and the like can be used.
Preferred among these pigments is carbon black. These pigments may be used without surface treatment, or may be used after surface treatment. Examples of the surface treatment include a method of surface coating a resin or wax, a method of attaching a surfactant, and a method of bonding a reactive substance (eg, a silane coupling agent, an epoxy compound, a polyisocyanate, etc.) to the pigment surface. Can be considered. The above surface treatment methods are described in “Properties and Applications of Metallic Soap” (Koshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). I have.

The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm.
Is preferably within the range. Pigment particle size 0.01μ
When it is less than m, the dispersion is not preferred in terms of stability in the coating solution for the photosensitive layer, and when it exceeds 10 μm, it is not preferred in terms of uniformity of the image recording layer. As a method for dispersing the pigment, a known dispersion technique used in the production of ink or toner can be used. As the disperser, an ultrasonic disperser,
Sand mills, attritors, pearl mills, super mills, ball mills, impellers, dispersers, KD mills, colloid mills, dynatrons, three-roll mills, pressure kneaders and the like can be mentioned. Details are described in "Latest Pigment Application Technology" (CMC Publishing, 1986). These infrared absorbers are used in an amount of 0.01 to 50% by weight, preferably 0.1 to 10% by weight, particularly preferably 0.5 to 10% by weight in the case of dyes, based on the total solid content of the lithographic printing material. In particular, it can be particularly preferably added to the lithographic printing material in a ratio of 3.1 to 10% by weight. If the added amount of the infrared absorber is less than 0.01% by weight, the sensitivity becomes low,
On the other hand, if it exceeds 50% by weight, stains occur in the non-image area during printing. From the viewpoint of facilitating on-press development and not contaminating the printing press, it is desirable to use a dye as the infrared absorber.

[Acid Generator] The acid generator used in the lithographic printing material according to the present invention is a compound which generates an acid by heat or light, and is generally a photoinitiator for photocationic polymerization and a photoradical. Photoinitiators for polymerization, photodecolorants for pigments, photochromic agents, known compounds used for microresist, which generate an acid by light, and mixtures thereof, and the like can be appropriately selected. Can be used. For example, SI Schlesinger, Photogr. Sci. Eng.,
18,387 (1974), TSBal et al., Polymer, 21,423 (198
0) etc., U.S. Pat.No.4,069,055
No. 4,069,056, ammonium salts described in JP-A-3-140,140, etc., DCNecker et al., Macromolecules, 1
7,2468 (1984), CSWen et al., Teh, Proc. Conf.Ra.
d.Curing ASIA, p478, Tokyo, Oct (1988), U.S. Pat.Nos. 4,069,055 and 4,069,056, phosphonium salts described in JVCrivello et al., Macromolecules, 10 (6), 1
307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988)
, European Patent No. 104,143, U.S. Patent No. 339,049, No. 410,201, JP-A-2-150,848, JP-A-2-296,514
No., etc., JVCrivello et al., P
olymer J. 17, 73 (1985), JVCrivello et al., J. Org.
Chem., 43, 3055 (1978), WRWatt et al., J. Polymer
Sci., Polymer Chem. Ed., 22, 1789 (1984), JVCrive
llo et al., Polymer Bull., 14,279 (1985), JVCrive
llo et al., Macromolecules, 14 (5), 1141 (1981), J.
V. Crivello et al., J. Polymer Sci., Polymer Chem. E
d., 17,2877 (1979), EP 370,693, U.S. Pat.No. 3,902,114, EP 233,567, 297,443
Nos. 297,442; U.S. Pat.Nos. 4,933,377; 410,20
No. 1, 339,049, 4,760,013, 4,734,444
No. 2,833,827, German Patent No. 2,904,626, No. 3,60
Nos. 4,580 and 3,604,581, etc.
JVCrivello et al., Macromolecules, 10 (6), 1307 (1
977), JVCrivello et al., J. Polymer Sci., Polymer
Chem. Ed., 17, 1047 (1979), etc., selenonium salts, CSWen et al., Teh, Proc. Conf. Rad. Curing A
Onium salts such as arsonium salts described in SIA, p478, Tokyo, Oct (1988), U.S. Pat.No. 3,905,815, JP-B-46
-4605, JP-A-48-36281, JP-A-55-32070, JP-A-60-239736, JP-A-61-169835, JP-A-61-16983
No. 7, JP-A-62-58241, JP-A-62-212401, JP-A-62-212401
63-70243, organic halogen compounds described in JP-A-63-298339, etc., K. Meier et al., J. Rad.Curing, 13 (4), 26
(1986), TPGill et al., Inorg. Chem., 19, 3007 (19
80), D. Astruc, Acc. Chem. Res., 19 (12), 377 (189
6), organometallics / organic halides described in JP-A-2-14145, S. Hayase et al., J. Polymer Sci., 25, 753 (19
87), E. Reichman et al., J. PolymerSci., Poliymer C
hem. Ed., 23, 1 (1985), QQZhu et al., J. Photoche.
m., 36, 85, 39, 317 (1987), B. Amit et al., Tetrahe
dron Lett., (24) 2205 (1973), DHR Barton et al.,
J. Chem. Soc., 3571 (1965), PMCollins et al., JC
hem. Soc., Perkin I, 1695 (1975), M. Rudinstein et.
al., Tetrahedron Lett., (17), 1445 (1975), JWWalke
r et al., J. Am. Chem. Soc., 110, 7170 (1988), SCB
usman et al., J. Imaging Technol., 11 (4), (1985)
, HM Houlihan et al., Macromolecules, 21, 2001 (198
8), PMCollins et al., J. Chem. Soc., Chem. Commu
n., 532 (1972), S. Hayase et al., Macromolecules, 1
8,1799 (1985), E. Reichmanis et al., J. Electrochem. S
oc., Solid State Sci. Technol., 130 (6), FMHouli
han et al., Macromolecules, 21, 2001 (1988), European Patent Nos. 0290,750, 046,083, 156,535, and 271,
Nos. 851, 0,388,343, U.S. Pat.
4,181,531, JP-A-60-198538, JP-A-53-133022
TUNOOKA et al., Polymer Preprints Japan, 35
(8), G. Berner et al., J. Rad. Curing, 13 (4), WJM
ijs et al., Coating Technol., 55 (697), 45 (1983), A
kzo, H. Adachi et al., Polymer Preprints, Japan, 37
(3), European Patent Nos. 0199,672, 84515, and 199,672
No. 044,115, No. 0101,122, U.S. Pat.No. 4,618,55
No. 4, No. 4,371,605, No. 4,431,774, JP-A-64-181
No. 43, compounds disclosed in JP-A-2-245756, JP-A-3-140109, etc., which generate sulfonic acid by photolysis, such as iminosulfonates, and disulfones described in JP-A-61-166544. Compounds can be mentioned.

Further, compounds having an acid generator introduced into the main chain or side chain of the polymer, for example, MEWoodhouse et al., J. Am.
Am. Chem. Soc., 104, 5586 (1982), SPPappas et a
l., J. Imaging Sci., 30 (5), 218 (1986), S. Kondo et.
al., Makromol. Chem. RapidCommun., 9,625 (1988),
Y. Yamada et al., Makromol, Chem. 152, 153, 163 (197
2), JVCrivello et al., J. Polymer Sci., Polymer
Chem. Ed., 17,3845 (1979), U.S. Pat.
No., German Patent No. 3914407, JP-A-63-26653, JP-A-55
-164824, JP-A-62-69263, JP-A-63-14603, JP-A-63-163452, JP-A-62-153853, JP-A-63-146
Compounds described in No. 029 and the like can be used. Furthermore, VNRPillai, Synthesis, (1), 1 (1980), A. Abad
et al., Tetrahedron Lett., (47) 4555 (1971), DHR
Compounds that generate an acid by light described in Barton et al., J. Chem. Soc., (C), 329 (1970), U.S. Pat. No. 3,779,778, and EP 126,712 can also be used.

Among the above compounds which generate an acid by heat or light, those which are particularly effectively used are shown below. (1) The following general formula (PAG) substituted with a trihalomethyl group
The oxazole derivative represented by 1) or the general formula (PAG)
An S-triazine derivative represented by 2).

[0017]

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In the formula, R ¹ represents a substituted or unsubstituted aryl or alkenyl group, R ² represents a substituted or substituted aryl, alkenyl or alkyl group, or —CY ₃ . Y represents a chlorine atom or a bromine atom. Specific examples include the following compounds, but the present invention is not limited thereto.

[0019]

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[0020]

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(2) An iodonium salt represented by the following general formula (PAG3) or a sulfonium salt represented by the following general formula (PAG4).

[0022]

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In the formula, Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group. Preferred substituents include an alkyl group, a haloalkyl group, a cycloalkyl group,
Aryl group, alkoxy group, nitro group, carboxy group,
Examples include an alkoxycarbonyl group, a hydroxy group, a mercapto group, and a halogen atom. R ³ , R ⁴ and R ⁵ each independently represent a substituted or unsubstituted alkyl group or aryl group. Preferred are an aryl group having 6 to 14 carbon atoms, an alkyl group having 1 to 8 carbon atoms, and substituted derivatives thereof. Preferred substituents are an alkoxy group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, a nitro group, a carboxyl group, a hydroxy group and a halogen atom for the aryl group, and a substituent for the alkyl group. Carbon number 1
8 is an alkoxy group, a carboxyl group, or an alkoxycarbonyl group.

Z^-Represents a counter anion, for example, B
F_Four, AsF₆ ^-, PF₆ ^-, SbF₆ ^-, Si
F₆ ^2-, ClO_Four ^-, CF_ThreeSO_Three ^-Perfluoro such as
Alkanesulfonic acid anion, pentafluorobenzene
Sulfonic acid anion, naphthalene-1-sulfonic acid ani
Condensed polynuclear aromatic sulfonate anions such as on
Quinone sulfonate anion, 9,10-dimethoxyan
Toracene-2-sulfonic acid anion, containing sulfonic acid group
Dyes and the like can be mentioned, but are not limited to these
is not. Also, R^Three, R^FourAnd R^FiveTwo of them
Ar¹And Ar^TwoIs through each single bond or substituent
May be combined.

Specific examples include the following compounds, but are not limited thereto.

[0026]

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[0027]

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The above-mentioned onium salts represented by the general formula (PAG3) or (PAG4) are known, for example, JWKnap
czyk et al., J. Am. Chem. Soc., 91, 145 (1969), AL
Maycok et al., J. Org.Chem., 35, 2532, (1970), E. Go
ethas et al., Bull.Soc.Chem.Belg., 73,546, (196
4), HM Leicester, J. Ame.Chem. Soc., 51, 3587 (1
929), JVCrivello et al., J. Polym. Chem. Ed., 1
8,2677 (1980); U.S. Pat.Nos. 2,807,648 and 4,247,47
No. 3, JP-A-53-101,331 and the like. (3) Disulfone derivatives represented by the following general formula (PAG5) or iminosulfonate derivatives represented by the following general formula (PAG6).

[0029]

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Where Ar^ThreeAnd Ar^FourAre replaced independently
Or an unsubstituted aryl group. R ⁶Is replaced or nothing
It represents a substituted alkyl group or an aryl group. A is replacement
Or unsubstituted alkylene group, alkenylene group or aryl
Represents a len group. Specific examples include the compounds shown below.
However, the present invention is not limited to these.

[0031]

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[0032]

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The amount of the acid generator is usually in the range of 0.001 to 40% by weight, preferably 0.01 to 20% by weight, more preferably 0 to 20% by weight, based on the total solid content of the lithographic printing material. It is used in the range of 0.1 to 5% by weight.

[Acid-Crosslinkable Compound] The acid-crosslinkable compound used in the lithographic printing material according to the present invention refers to a compound which crosslinks in the presence of an acid, such as a hydroxymethyl group, an acetoxymethyl group, or an alkoxy group. Aromatic compounds and heterocyclic compounds poly-substituted by a methyl group are mentioned, and a preferable example is a compound obtained by condensing phenols and aldehydes under basic conditions. Preferred among the above compounds are, for example, compounds obtained by condensing phenol and formaldehyde under basic conditions as described above, similarly, compounds obtained from m-cresol and formaldehyde, and compounds obtained from bisphenol A and formaldehyde. Compound,
Compounds obtained from 4,4'-bisphenol and formaldehyde, and other compounds disclosed as resol resins in GB 2,082,339 are exemplified. These acid crosslinking compounds have a weight average molecular weight of 500 to 1
Those having a number average molecular weight of 200,000 to 50,000 and a molecular weight of 00000, are preferred.

Another preferred example is EP-A No. 0,
An aromatic compound substituted with an alkoxymethyl or oxiranylmethyl group disclosed in U.S. Pat.
P-A No. 0,133,216, DE-A No. 3,63
4,671, monomer and oligomer melamine-formaldehyde condensates and urea-formaldehyde condensates disclosed in DE 3,711,264; alkoxy substitution disclosed in EP-A 0,212,482 Compounds. Still other preferred examples are, for example, melamine-formaldehyde derivatives having at least two free N-hydroxymethyl, N-alkoxymethyl or N-acyloxymethyl groups. Among them, N-
Alkoxymethyl derivatives are particularly preferred. Also, low molecular weight or oligomeric silanols can be used as silicon-containing crosslinkers. Examples of these are dimethyl- and diphenyl-silanediols and oligomers which have already been precondensed and contain these units, for example EP-
No. 0,377,155 can be used.

Among the aromatic compounds and heterocyclic compounds poly-substituted with an alkoxymethyl group, the compound has an alkoxymethyl group at a position adjacent to the hydroxyl group, and the alkoxy group of the alkoxymethyl group has 18 or less carbon atoms. Compounds can be mentioned as preferable examples, and particularly preferable examples include compounds represented by the following general formulas (1) to (4).

[0037]

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[0038]

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In the formula, L _{1 to} L ₈ may be the same or different and represent an alkoxymethyl group substituted with an alkoxy group having 18 or less carbon atoms such as methoxymethyl, ethoxymethyl and the like. These are preferred because they have high crosslinking efficiency and can improve printing durability. The above compounds that are crosslinked by heat may be used alone,
Two or more types may be used in combination. The acid-crosslinkable compound according to the present invention accounts for 5 to 8 in the total solids of the lithographic printing material.
It is used in an amount of 0% by weight, preferably 10 to 75% by weight, particularly preferably 20 to 70% by weight. If the amount of the acid-crosslinkable compound is less than 5% by weight, the durability of the photosensitive layer of the resulting lithographic printing material is deteriorated, and if it exceeds 80% by weight, the storage stability is not preferred.

[Novolak resin] The novolak resin used in the lithographic printing material according to the present invention is a resin obtained by condensing phenols and aldehydes under acidic conditions. Preferred novolak resins include, for example, a novolak resin obtained from phenol and formaldehyde, a novolak resin obtained from m-cresol and formaldehyde, a novolak resin obtained from p-cresol and formaldehyde, a novolak resin obtained from o-cresol and formaldehyde, Novolak resin obtained from octylphenol and formaldehyde, novolak resin obtained from m- / p-mixed cresol and formaldehyde, phenol / cresol (m-, p-, o- or m- / p-, m- / o-, o -/ P- mixture) and a novolak resin obtained from formaldehyde. These novolak resins preferably have a weight average molecular weight of 800 to 200,000 and a number average molecular weight of 400 to 60,000. These novolak resins may be used alone or in combination of two or more. In the present invention, these novolak resins are 5 to 90% by weight, preferably 10 to 85% by weight, based on the total solid content of the lithographic printing material.
%, Particularly preferably from 20 to 80% by weight. If the amount of the novolak resin is less than 5% by weight, the durability of the photosensitive layer deteriorates, and if it exceeds 90% by weight, it is not preferable in terms of both sensitivity and durability.

[Other Components] In the lithographic printing material to which the production method of the present invention can be applied, the above-mentioned four components are essential, but various compounds other than these may be added as necessary. For example, a dye having a large absorption in the visible light region can be used as a colorant for an image. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black B
Y, oil black BS, oil black T-505
(Orient Chemical Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI4255)
5), methyl violet (CI42535), ethyl violet, rhodamine B (CI145170B),
Malachite green (CI42000), methylene blue (CI52015), etc., or JP-A-62-29
Dyes described in Japanese Patent No. 3247 can be exemplified. These dyes are preferably added because the image area and the non-image area can be easily distinguished after image formation. still,
The addition amount is 0.01 to 1 based on the total solid content of the lithographic printing material.
0% by weight.

In the lithographic printing material according to the present invention,
Japanese Patent Application Laid-Open No.
Nonionic surfactants as described in JP-A-2-251740 and JP-A-3-208514, and amphoteric as described in JP-A-59-121044 and JP-A-4-13149. Surfactants can be added. Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan triolate, monoglyceride stearic acid, and polyoxyethylene nonyl phenyl ether. Specific examples of the surfactant include alkyl di (aminoethyl) glycine, alkyl polyaminoethyl glycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N
-Tetradecyl-N, N-betaine type (for example, trade name Amogen K, manufactured by Daiichi Kogyo KK) and the like. The proportion of the nonionic surfactant and the amphoteric surfactant in the lithographic printing material is preferably 0.05 to 15% by weight, more preferably 0.1 to 5% by weight.

Further, a plasticizer may be added to the lithographic printing material according to the present invention, if necessary, in order to impart flexibility to the coating film. For example, butyl phthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or Oligomers and polymers of methacrylic acid are used.

Other than these, the above-mentioned onium salts, haloalkyl-substituted S-triazines, epoxy compounds, vinyl ethers, and Japanese Patent Application No. 7-18120.
A phenol compound having a hydroxymethyl group according to
A phenol compound having an alkoxymethyl group may be added.

The lithographic printing material according to the present invention can be usually produced by dissolving the above-mentioned components in a solvent and applying the resulting solution on a suitable support. As the solvent used herein, ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethylsulfoxide, sulfolane, γ-butyllactone, toluene,
Water and the like can be given, but not limited thereto. These solvents are used alone or as a mixture. The concentration of the above components (total solids including additives) in the solvent is preferably 1 to 50% by weight. The amount of coating (solid content) on the support obtained after coating and drying varies depending on the application, but generally 0.5 to 5.0 g / m ² is preferred for lithographic printing plates. As a method of applying, various methods can be used, for example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating,
Roll coating and the like can be mentioned. As the coating amount decreases, the apparent sensitivity increases, but the film characteristics of the image recording film deteriorate.

In the lithographic printing material of the present invention, a surfactant for improving coating properties, for example, JP-A-62-1
A fluorine-based surfactant as described in JP-A-70950 can be added. The preferred addition amount is 0.01 to 1% by weight, more preferably 0.05 to 0.5% by weight, based on the total solid content of the lithographic printing material.

The support used in the present invention is a dimensionally stable plate-like material such as paper, plastic (for example, polyethylene, polypropylene, polystyrene, etc.) laminated paper, metal plate ( For example, aluminum, zinc, copper, etc.), plastic film (for example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate,
Cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic film on which a metal is laminated or vapor-deposited as described above.

As the support of the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate which has good dimensional stability and is relatively inexpensive is particularly preferable. Suitable aluminum plates are a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of a different element, and may be a plastic film on which aluminum is laminated or vapor-deposited. The foreign elements contained in aluminum alloys include silicon, iron, manganese,
Copper, magnesium, chromium, zinc, bismuth, nickel, titanium and the like. The content of the foreign element in the alloy is at most 10% by weight or less. Aluminum which is particularly preferred in the present invention is pure aluminum. However, completely pure aluminum is difficult to produce due to refining technology, and therefore may contain a slightly different element. As described above, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate of a conventionally known and used material can be appropriately used. The thickness of the aluminum plate 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 0.4 mm.
mm to 0.8 mm.

Prior to roughening the aluminum plate, if necessary, a degreasing treatment with, for example, a surfactant, an organic solvent or an alkaline aqueous solution for removing rolling oil on the surface is performed. The surface roughening treatment of the surface of the aluminum plate is performed by various methods, for example, a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. It is performed by the method of causing. As a mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing an alternating or direct current in a hydrochloric acid or nitric acid electrolyte. Further, a method combining both of them can be used as disclosed in JP-A-54-63902. The aluminum plate thus roughened is subjected to an alkali etching treatment and a neutralization treatment, if necessary, and then subjected to an anodic oxidation treatment, if desired, in order to increase the water retention and abrasion resistance of the surface. As the electrolyte used for the anodic oxidation treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. Generally, sulfuric acid,
Phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of the electrolyte.

The anodizing treatment conditions vary depending on the electrolyte used and cannot be specified unconditionally. Generally, however, the concentration of the electrolyte is 1 to 80% by weight, the solution temperature is 5 to 70 ° C., and the current density is 5 to 60 A. / Dm ² , voltage 1-100V, electrolysis time 1
A range of 0 seconds to 5 minutes is appropriate. When the amount of the anodic oxide film is less than 1.0 g / m ² , the printing durability is insufficient or the non-image area of the lithographic printing plate is easily damaged, and the ink adheres to the damaged area during printing. So-called "scratch dirt" tends to occur. After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment as necessary. The hydrophilic treatment used in the present invention includes, for example, US Pat.
No. 066, No. 3,181,461, No. 3,280,
There is an alkali metal silicate (e.g., sodium silicate aqueous solution) method as disclosed in U.S. Pat. Nos. 734 and 3,902,734. In this method, the support is immersed in an aqueous solution of sodium silicate or electrolytically treated. Further, potassium fluoride zirconate disclosed in JP-B-36-22063 and U.S. Pat. Nos. 3,276,868, 4,158,461 and 4,689,272 are disclosed. A method of treating with polyvinyl phosphonic acid as described above is used.

In the lithographic printing material according to the present invention, an undercoat layer can be provided on the support, if necessary. Various organic compounds are used as the undercoat layer component, for example, carboxymethylcellulose, dextrin, gum arabic,
Phosphonic acids having an amino group such as 2-aminoethylphosphonic acid, optionally substituted phenylphosphonic acid, naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid Organic phosphonic acid, phenylphosphoric acid optionally having a substituent, naphthylphosphoric acid, organic phosphoric acid such as alkyl phosphoric acid and glycerophosphoric acid, phenylphosphinic acid optionally having a substituent, naphthylphosphinic acid,
Selected from organic phosphinic acids such as alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and hydrochlorides of amines having a hydroxy group such as hydrochloride of triethanolamine. You may use it. The coating amount of the organic undercoat layer is suitably from ² to 200 mg / m ² .

As described above, a lithographic printing plate using the lithographic printing material according to the present invention can be prepared.
This lithographic printing plate material is image-exposed by a solid-state laser and a semiconductor laser that emit infrared rays having a wavelength of 760 nm to 1200 nm. In the present invention, the developing treatment may be performed immediately after the laser irradiation, but it is preferable to perform the heating treatment between the laser irradiation step and the developing step. The heat treatment is preferably performed in a range of 80 ° C. to 150 ° C. for 10 seconds to 5 minutes. By this heat treatment, the laser energy required for recording at the time of laser irradiation can be reduced.

After performing a heat treatment as required, the lithographic printing material according to the present invention is developed with an alkaline aqueous solution. As the developer and replenisher for the lithographic printing material according to the present invention, conventionally known aqueous alkaline solutions can be used. For example, sodium silicate, potassium silicate, third
Sodium phosphate, tribasic potassium phosphate, tribasic ammonium phosphate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate And inorganic alkali salts such as ammonium bicarbonate, sodium borate, potassium borate, ammonium borate, sodium hydroxide, ammonium hydroxide, potassium hydroxide and lithium hydroxide. Also, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine and pyridine are also used. These alkali agents are used alone or in combination of two or more. Among these alkali agents, particularly preferred developers are aqueous silicate solutions such as sodium silicate and potassium silicate. The reason is that the developability can be adjusted by the ratio and the concentration of the silicon oxide SiO ₂ and the alkali metal oxide M ₂ O which are the components of the silicate. For example, JP-A-54-62004 discloses An alkali metal silicate described in JP-B-57-7427 is effectively used.

In the case of performing development using an automatic developing machine, an aqueous solution having a higher alkali strength than the developing solution (replenisher)
It has been known that a large amount of lithographic printing plate material can be processed without replacing the developing solution in the developing tank for a long time by adding to the developing solution. This replenishment system is also preferably applied in the present invention. Various surfactants and organic solvents can be added to the developing solution and the replenishing solution as required for the purpose of accelerating or suppressing the developing property, dispersing the developing residue and improving the ink affinity of the printing plate image area. Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. Further, the developing solution and the replenisher may contain, if necessary, a reducing agent such as a sodium salt or a potassium salt of an inorganic acid such as hydroquinone, resorcinol, sulfurous acid, and bisulfite, and an organic carboxylic acid, an antifoaming agent, and a water softener. Can be added. The printing plate developed using the above developer and replenisher is post-treated with washing water, a rinsing solution containing a surfactant and the like, and a desensitizing solution containing gum arabic and a starch derivative. As the post-processing when the lithographic printing material according to the present invention is used as a printing plate material, these processings can be used in various combinations.

In recent years, in the plate making / printing industry, automatic developing machines for printing plate materials have been widely used in order to rationalize and standardize plate making operations. This automatic developing machine generally consists of a developing section and a post-processing section, and consists of a device for transporting printing plate material, each processing solution tank and a spray device, and pumps the exposed printing plate horizontally while pumping it. Each processing liquid is sprayed from a spray nozzle to perform development processing.
Recently, a method has been known in which a printing plate material is immersed and transported by a submerged guide roll or the like in a processing liquid tank filled with a processing liquid, and the processing is performed. In such an automatic processing, the processing can be performed while replenishing each processing liquid with a replenisher according to the processing amount, the operating time, and the like. Further, a so-called disposable processing method in which processing is performed with a substantially unused processing liquid can also be applied.

The lithographic printing plate obtained as described above can be subjected to a printing step after applying a desensitizing gum as required, but when a lithographic printing plate having a higher printing durability is desired to be obtained. Is subjected to a burning process. When burning a lithographic printing plate, make sure that the burning surface is
No. 2518, No. 55-28062, JP-A-62-3
It is preferable to treat with a surface-regulating liquid as described in JP-A Nos. 1859 and 61-159655. As a method, a sponge or absorbent cotton impregnated with the surface conditioning liquid is applied on a lithographic printing plate, or a method in which the printing plate is immersed in a vat filled with the surface conditioning solution and applied, Application by an automatic coater or the like is applied. Further, it is more preferable to make the application amount uniform with a squeegee or a squeegee roller after the application. In general, it is appropriate that the amount of the surface conditioning liquid applied is 0.03 to 0.8 g / m ² (dry weight).

The lithographic printing plate to which the surface conditioning liquid has been applied is dried if necessary, and then heated to a high temperature using a burning processor (for example, BP-1300, a burning processor sold by Fuji Photo Film Co., Ltd.). Is done. The heating temperature and time in this case depend on the type of the component forming the image, but may be 1 to 180 ° C. to 300 ° C.
A range of up to 20 minutes is preferred. The burned lithographic printing plate can be subjected to conventional treatments such as washing with water and gumming, if necessary.However, a surface conditioning liquid containing a water-soluble polymer compound or the like is used. In such a case, a so-called desensitizing treatment such as gumming can be omitted. The lithographic printing plate obtained by such a process is set on an offset printing machine or the like and used for printing a large number of sheets.

[0058]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 An aluminum plate (material 1050) having a thickness of 0.30 mm was washed with trichlorethylene and degreased, and then its surface was grained using a nylon brush and a 400-mesh pumistone-water suspension, and washed well with water. did. 45 ℃
The substrate was immersed in a 25% aqueous sodium hydroxide solution for 9 seconds to perform etching, washed with water, and further immersed in 2% HNO _{3 for} 20 seconds to wash with water. At this time, the etching amount of the grained surface was about 3 g / m ² . Next, the plate was placed in 7% H ₂ SO ₄
Was used as an electrolyte to form a 3 g / m ² DC anodic oxide coating at a current density of 15 A / dm ² , and then washed with water and dried. Next, the following undercoat liquid was applied to this aluminum plate, and dried at 80 ° C. for 30 seconds. The coated amount after drying was 10 mg / m ² .

(Undercoat solution) β-alanine 0.1 g Phenylphosphonic acid 0.05 g Methanol 40 g Pure water 60 g Further, the following photosensitive solution was added to this aluminum plate by adding triethylamine salt of p-toluenesulfonic acid to pH 5.0.
, And dried at 100 ° C. for 2 minutes to obtain a negative photosensitive lithographic printing plate. The weight of the coating liquid after drying was 2.0 g / m ² . In addition, p before the preparation of this photosensitive solution
H was 8.0.

(Photosensitive solution) Infrared absorbent 0.1 g (trade name: NK-2014, manufactured by Japan Photographic Dye Laboratories, Inc.) 4- (p-N, N-bis (ethoxycarbonylmethyl) aminophenyl)- 2,6-bis (trichloromethyl) -S-triazine 0.1 g Novolak resin obtained from cresol and formaldehyde 1.2 g (meta: para ratio = 8: 2, weight average molecular weight 5800) Resole obtained from bisphenol A and formaldehyde Resin 1.0 g (weight average molecular weight 1600) Dye in which the counter ion of Victoria Pure Blue BOH is converted to 1-naphthalene-sulfonic acid 0.05 g Fluorosurfactant 0.06 g (MegaFac F-177, Dainippon Ink & Chemicals, Inc.) 20 g of methyl ethyl ketone 7 g of methyl alcohol pH adjuster (p -Toluenesulfonic acid triethylamine salt) 0.01 g

The obtained negative type lithographic printing plate was treated with a semiconductor laser (wavelength: 825 nm,
Beam diameter: 1 / e ² = 6 μm) and a linear velocity of 8 m / s
The plate output was adjusted to 110 mW by ec, and exposure was performed. After a heat treatment at 110 ° C. for 1 minute after the exposure, a developing solution manufactured by Fuji Photo Film Co., Ltd., DP-4 (1: 8), a rinsing solution FR-
3 (1: 7) through an automatic processor.
Next, gum GU-7 (1: 1) manufactured by Fuji Photo Film Co., Ltd.
The plate was processed in 1) and printed with a Heidel KOR-D machine. 65,000 good prints without stains on the non-image area were obtained.

Comparative Example 1 In Example 1, the coating solution was used as it was without adjusting the pH of the photosensitive solution. 7. The pH of the coating solution was measured.
It was 0. Exposure, heat treatment, development and subsequent treatments were carried out in the same manner as in Example 1, and printing was performed. However, only indistinct and weak print images were obtained.

Examples 2 to 4 (Synthesis of Crosslinking Agent) 20 g of 1- [α-methyl-α- (4-hydroxyphenyl) ethyl] -4- [α, α-bis (4-hydroxyphenyl) ethyl] benzene Was dissolved in 100 ml of aqueous potassium hydroxide solution (10%). 60 ml of formalin (37%) was added dropwise to this reaction solution over 1 hour while stirring at room temperature. After the reaction solution was further stirred at room temperature for 6 hours, it was poured into an aqueous sulfuric acid solution to cause crystallization. After thoroughly washing the obtained paste-like precipitate with water, methanol 3
Recrystallization using 0 ml gave a white powder.
Yield 20 g. The obtained compound was analyzed by NMR for 1- [α
-Methyl-α- (4-hydroxyphenyl) ethyl]-
It was found to be hexamethylolated 4- [α, α-bis (4-hydroxyphenyl) ethyl] benzene. Reversed phase HPLC (column: Shimpac CLC-ODS
(Manufactured by Shimadzu Corporation), solvent: methanol / water = 60/40
→ → 90/10) The purity of the hexamethylolated product is 9
2%.

20 g of this hexamethylol compound was dissolved by heating in 1000 ml of methanol, and 1 ml of concentrated sulfuric acid was added thereto.
The mixture was heated under reflux for 2 hours. After cooling the reaction solution, potassium carbonate 2
g, and the mixture was further stirred and concentrated.
After washing with water and drying, the solvent was distilled off to obtain a white solid. Yield 22 g. The obtained compound was analyzed by NMR for 1-
[Α-methyl-α- (4-hydroxyphenyl) ethyl] -4- [α, α-bis (4-hydroxyphenyl)
[Ethyl] benzene was found to be hexamethoxymethylated. Reversed phase HPLC (column: Shimpac CLC
-ODS (manufactured by Shimadzu Corporation), solvent: methanol / water = 6
(0/40 → 90/10), the purity of the hexamethoxymethylated product was 90%.

(Production of a lithographic printing plate) The following photosensitive solution was applied to an undercoated aluminum plate treated in the same manner as in Example 1,
Add the triethylamine salt of toluenesulfonic acid,
Each of the coating solutions whose pH was adjusted to 3.0, 4.0 and 5.0 was applied and dried at 100 ° C. for 2 minutes to obtain negative photosensitive lithographic printing plates A, B and C, respectively. 2, 3, 4
And The weight of the photosensitive layer after drying was 2.0 g / m ² .
The unadjusted pH of this photosensitive solution was 2.5.

(Photosensitive solution) Infrared absorbing dye having the following structural formula 0.1 g Crosslinking agent 0.21 g Phenol-formaldehyde novolak 2.1 g (weight average molecular weight 12000) Diphenyliodonium 9,10-dimethoxy anthracene sulfonate 0.02 g Fluorine 0.06 g (Megafac F-177, manufactured by Dainippon Ink and Chemicals, Inc.) methyl ethyl ketone 15 g 2-methoxy-1-propanol 12 g

[0067]

Embedded image

The obtained negative type lithographic printing plates A, B, and C were processed and printed under the same conditions as in Example 1, and all of Examples 2 to 4 showed good prints without stain on the non-image area. was gotten. The number of prints obtained at this time was 60,000.

Comparative Examples 2 to 3 The negative type lithographic printing plate D was obtained by directly using the photosensitive solution in Example 2 without adjusting the pH (pH 2.5) without preparing the same.
And After storing the coating solution whose pH was not adjusted for one day, it was coated under the same conditions to obtain a negative type lithographic printing plate E, which was designated as Comparative Example 3. These were processed under the same conditions as in Example 1,
As a result of printing, the negative type lithographic printing plate D was stained in the non-image area, and a good printed matter was not obtained. In the case of the negative type lithographic printing plate E, the sensitivity was greatly reduced, and no good printed matter was obtained.

[0070]

According to the present invention, by adjusting the pH of the coating solution within a predetermined range, plate making can be directly performed from digital data of a computer or the like, and furthermore, the stability during storage is excellent, and the printing durability during printing is excellent. A method for stably producing a negative type lithographic printing plate material having good properties can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03F 7/004 506 G03F 7/004 506 7/16 7/16

Claims (1)

[Claims] 1. A method for producing a negative lithographic printing material, comprising a step of applying a coating solution for a photosensitive layer containing a novolak resin, an acid generator, an acid-crosslinkable compound, and an infrared absorber to a support. Wherein the pH is adjusted to a range of 3 to 7 when preparing the lithographic printing plate material.