JPH1016175A - Original print of litho printing plate and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a litho printing plate and a production method thereof having a sensitivity available of a simple and easy laser imaging and a simple and easy treatment process with a high resolution avoiding a print dirt, superior in a print resistance by a rapid, economical and digital imaging means. SOLUTION: After a printing plate which is orderly laminated with a positive type sensitized layer or a negative type sensitized layer and a laser light sensitivity layer having a sensitivity against a visible-infrared light laser and a non- sensitivity against a light of a wave length sensitizable of the positive type or the negative type sensitized layer is image exposed by the visible light - the infrared light laser on a support, a whole exposer is effected by a light of a wave length sensitizable of the positive type or the negative type sensitized layer, and a solubilized part of a sensitized layer is soluted and removed by an alkaline solution. By this, the laser light sensitivity layer includes (a) a visible - an infrared absorber and/or (b) light absorber of a wave length sensitizable of a positive type or a negative type sensitivity layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate precursor in which a positive or negative photosensitive layer and a specific laser light-sensitive layer are sequentially laminated on a support, and a method for making the same. The present invention relates to a lithographic printing plate precursor with a simple processing step and a method of making a lithographic printing plate precursor with a simple and compact apparatus.

[0002]

BACKGROUND OF THE INVENTION Lithographic printing techniques are based on the immiscibility of oil and water, with oily materials or inks being preferentially retained in image areas and water being preferentially retained in non-image areas. The ink held in the image area is then transferred to the surface of the material from which the image is reproduced (eg, paper, fabric, etc.). Usually, the ink is transferred to an intermediate, called a blanket, and then, once the image is reproduced, the ink is again transferred to the surface of the blanket.

[0003] Lithographic printing plate precursors of a type widely used today are mainly composed of a positive type photosensitive agent mainly composed of a quinonediazide compound and a phenol resin, an acrylic monomer or a prepolymer on an aluminum base support. A PS plate having a photosensitive layer such as a negative photosensitive agent is generally used.However, these photosensitive agents have low sensitivity. Is going.

On the other hand, due to advances in computer image processing, large-capacity data storage, and data communication technologies, in recent years, computer operations have been consistently performed from document input, correction, editing, layout, to page grouping, and high-speed communication networks and satellite communications have been developed. As a result, an electronic editing system that can immediately output to a remote terminal plotter has been put to practical use. In particular, the demand for an electronic editing system is high in the newspaper printing field, which requires immediacy.

[0005] However, a direct type printing plate for producing a printing plate directly from the output of a terminal plotter cannot solve the problem of sensitivity as described above, and is hardly practically used. That is, the light source of the output plotter (for example, a He-Ne laser,
One of the reasons is that it is difficult to develop a direct type printing plate having a sensitivity high enough to produce a printing plate in a practical time by a semiconductor laser or the like.

[0006] In order to provide a direct type printing plate having a high sensitivity capable of drawing by the above-mentioned laser beam, a lithographic printing plate in which a PS plate is combined with a highly sensitive material system has been proposed. For example, JP-A-56-47040 and JP-A-59-157641.
No. 60-61752, etc., a silver salt emulsion layer is provided on a PS layer photosensitive layer, silver halide is exposed by a laser beam, and a silver salt image is formed by development and fixing. A method of forming a lithographic printing plate precursor by solubilizing exposed portions (non-image portions) of a PS plate photosensitive layer by exposing the entire surface to ultraviolet light using a mask as a mask and eluting the same. However, in this method, there is a problem in that the use of silver halide requires two development steps and a processing solution almost in the same manner as in a conventional lithographic film / PS plate system.

A method in which a high-sensitivity electrophotograph is combined with a PS plate, that is, a method in which a toner image is formed using only the electrophotography and a photoconductive layer in a non-image area is eluted, is described in, for example, Japanese Patent Application Laid-Open Publication No. H11-163873. No. 37-17162, 38-69
Nos. 61, 38-7758, 41-2426, 46-39405, JP-A-50-19509, and 5
Nos. 0-19510, 52-2437 and 54-14
No. 5538, No. 54-134632, No. 55-105
No. 254, No. 55-153948, No. 55-1612
No. 50, No. 57-147656, No. 57-16186
No. 3 publication. However, in the above method, when the non-image portion of the electrophotographic photosensitive member is removed with the eluent, the eluent penetrates into the photoconductive layer, and there is a disadvantage that the portion is removed and the image reproducibility is reduced.

[0008] In order to overcome such a drawback, the purpose of using both a photoconductive compound and a photosensitive substance in a photosensitive layer is to achieve both high sensitivity of an electrophotographic system and good print image reproducibility of a positive photosensitive layer. The composite type lithographic printing plate precursor described in
No. 0648, No. 58-150953, No. 58-162
Nos. 960 and 58-162961. The positive photosensitive layer described in each of these publications uses an o-quinone azide compound or the like as a photosensitive substance, so that at the time of overall exposure, the photoconductive compound acts as a filter for the photopolymer, and the overall exposure time is reduced. However, there is a problem that a good image cannot be obtained unless the length is extremely long. In addition, since the electrophotographic method is used, each step of charging, exposure, toner development, and fixing is required, and there is a disadvantage that the apparatus becomes large.

As described above, a lithographic printing plate precursor in which a conventional PS plate having good printing performance is combined with a high-sensitivity silver halide or electrophotographic material system is developed in the same manner as a lithographic film in a silver halide system. A processing step and a processing liquid are required, and the electrophotographic method requires each step of charging, exposure, toner development, and fixing, and has a problem that the apparatus becomes large.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a high-sensitivity, high-resolution image processing apparatus which has a simple processing step and is suitable for forming an image by laser scanning exposure. Providing excellent lithographic printing plate precursors, and
The processing process is simple and the equipment can be made compact.
Another object of the present invention is to provide a method of making a lithographic printing plate precursor having excellent printing durability and image quality.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, a positive photosensitive layer or a negative photosensitive layer and a photosensitive layer on a support having a hydrophilic surface. Insensitive to light of a wavelength that can be sensitized, and
A lithographic printing plate precursor, which is formed by sequentially laminating laser light-sensitive layers that receive and disappear visible to infrared laser light, and a support having a hydrophilic surface, a positive photosensitive layer or Lithographic printing in which a negative photosensitive layer and a laser light-sensitive layer which is insensitive to light having a wavelength capable of sensitizing the photosensitive layer and which is sensitive to visible to infrared laser light and disappears are sequentially laminated. After the plate precursor is image-exposed with visible to infrared laser light, the photosensitive layer is exposed to light of a wavelength capable of sensitizing the entire surface, and the alkaline solution-soluble portion of the photosensitive layer is dissolved and removed with an alkaline solution. It has been found that the above object can be achieved by a method of making a lithographic printing plate precursor characterized by the above, and the present invention has been completed.

In the present invention, the outermost surface is provided with a laser light-sensitive layer which is insensitive to light having a wavelength capable of sensitizing the photosensitive layer and which is sensitive to visible to infrared laser light and disappears. Therefore, the laser light energy used for recording is absorbed by this laser light-sensitive layer and converted into thermal energy, and the resulting reactions such as ablation or combustion, melting, decomposition, vaporization, and explosion cause rapid internal changes. As a result, the substance is completely expelled from the laser light-sensitive layer, and the portion of the laser light-sensitive layer disappears to form a recorded image. The laser light-sensitive layer absorbs the laser light, but is insensitive to light having a wavelength that can expose the positive or negative photosensitive layer laminated thereunder. In the entire surface exposure step of the photosensitive layer, it functions as a mask. That is, a recorded image corresponding to a lith film used for a conventional PS plate is formed on the laser light receiving layer by the image exposure of the laser light.

Therefore, in the subsequent overall exposure with light having a wavelength capable of sensitizing the photosensitive layer, the non-image portion of the laser light sensitive layer functions as a mask. At this time, when the photosensitive layer is a positive photosensitive layer, the irradiated portion when the entire surface is exposed becomes soluble in an alkaline solution. On the other hand, when the photosensitive layer is a negative photosensitive layer, the irradiated portion when the entire surface is irradiated with light becomes insoluble in the alkaline solution, and the non-irradiated portion becomes soluble. Therefore, after the entire surface is exposed, the entire photosensitive layer is treated with an alkaline solution, and the alkaline solution-soluble portion of the photosensitive layer is removed, whereby a positive or negative type lithographic printing plate precursor can be produced.

In the present invention, a processing step is simple, rapid, economical, and digital, by combining a laser light-sensitive layer having sensitivity capable of performing simple laser imaging and a PS plate having good printing quality. It is characterized in that a lithographic printing plate precursor can be made by imaging means.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the lithographic printing plate precursor is obtained by forming a positive photosensitive layer or a negative photosensitive layer (hereinafter, referred to as a PS photosensitive layer) and a light having a wavelength capable of sensitizing the photosensitive layer on a support having a hydrophilic surface. A laser light-sensitive layer that is insensitive to and disappears upon being detected by visible to infrared laser light (hereinafter, appropriately,
A visible-to-infrared laser light-sensitive layer or a laser light-sensitive layer) are sequentially laminated, and a suitable plate-making method using the lithographic printing plate precursor is provided.

In the lithographic printing plate precursor, the visible-to-infrared laser light-sensitive layer laminated on the uppermost portion will be described.
The laser light-sensitive layer is exposed by laser image exposure.
It plays the role of the squirrel film used in the conventional PS plate, has sensitivity to visible to infrared laser light, is lost by the laser, and is laminated below the laser light sensitive layer. It is necessary to be insensitive to light having a wavelength capable of sensitizing the light-sensitive layer. For that purpose, the laser light-sensitive layer has at least one selected from the group consisting of (a) a visible to infrared light absorber, and (b) a light absorber having a wavelength capable of sensitizing the positive or negative photosensitive layer. It is preferable to contain one kind. Further, a binder can be further contained as necessary. The constituent components of the infrared laser light-sensitive layer that can be used for a semiconductor laser suitable for practical use will be described below.

(A) Visible to infrared light absorbing agent (hereinafter referred to as appropriate) constituting the laser light sensitive layer of the lithographic printing plate precursor according to the present invention.
As an infrared light absorber), various organic materials and inorganic materials that absorb light having a wavelength of visible to infrared laser used for image exposure (writing) can be used. For example, as a specific example of the infrared light absorber, “Infrared Absorbing D” written by Fumio Matsui (edited by Ken Matsuoka)
yes ", PlenumPress, New York
(1990), cyanine dyes described in U.S. Pat. No. 4,948,777 and the like, merocyanine dyes, squarylium dyes, croconium dyes, quinoid dyes, metal thiolate dyes, and the like. Infrared light absorbing pigments, phthalocyanine compounds, organic pigments such as carbon black, graphite, etc., dark inorganic pigments such as copper chromite, chromium oxide, cobalt chromium aluminate, metals such as aluminum, copper and zinc, indium tin oxide And metal oxides such as tungsten oxide, manganese oxide and titanium oxide, and alloys mainly containing bismuth and indium copper. Of these, metal materials such as metals, metal oxides, and alloys generally function as both (a) an infrared light absorber and (b) an absorber of light having a wavelength capable of sensitizing the photosensitive layer. In particular, in addition to (a) the infrared light absorber
(b) Even if the photosensitive layer does not contain an absorber of light having a wavelength capable of sensitizing the photosensitive layer, the photosensitive layer has a sufficient function as a photosensitive layer, and a binder is not required for forming the photosensitive layer. (a) The infrared light absorbing agent can be used at a coating amount of about 0.01 to ² g / m ² .

(B) As the light-absorbing agent capable of sensitizing the PS photosensitive layer, any dye which makes the light capable of sensitizing the positive photosensitive layer or the negative photosensitive layer substantially insensitive can be used. Typical examples thereof include yellow dyes. For example, dicyanovinylaniline dyes described in JP-A-61-28451, U.S. Pat.
No. 82, the pyrazolone arylidene dye described in U.S. Pat. No. 4,866,029, the quinophthalone dye described in EP 318,032, 63-3
No. 0393, azopyrazolone dyes described in JP-A-63-182190, and pyrazolinedione ants described in U.S. Pat. No. 4,853,366. Leylidene dyes, azopyridone dyes described in JP-A-63-39380, azodiaminopyridine dyes described in U.S. Pat. No. 4,914,077, and EP-A 331,170. Thiadiazole azo dyes, nitrophenylazoaniline dyes described in JP-A-60-31565, U.S. Pat.
No. 891,353, pyrazoline thiazole dyes and the like. (b) The amount of the light absorber having a wavelength capable of sensitizing the photosensitive layer is such that at the time of overall exposure, the light of the wavelength is absorbed so that the optical density is such that the positive or negative photosensitive layer can function as a mask. Is added to The amount of this (b) light absorber is preferably used so that the optical density of the photosensitive layer becomes 2.0 or more.

As the binder for forming the laser light-sensitive layer, any polymer material satisfying the following requirements can be used. (1) the infrared laser light-sensitive layer is effectively removed by the heat generated by the infrared light absorber when the infrared laser light-sensitive layer is exposed to the infrared laser light; and (2) after the image exposure by the infrared laser light, It is two points that it can be removed from the surface of the positive or negative photosensitive layer. That is, a polymer in which the binder is soluble / swellable or dispersible in the eluate of the positive or negative photosensitive layer, and can uniformly dissolve or disperse other materials in the laser light sensitive layer. Material. Examples of these include cellulose and cellulose derivatives such as nitrocellulose and ethyl cellulose, acrylic esters such as polymethyl methacrylate and polybutyl methacrylate, homopolymers and copolymers of methacrylic esters, isoprene, and various types such as styrene-butadiene. Synthetic rubbers, homopolymers of vinyl esters such as polyvinyl acetate, copolymers such as vinyl acetate-vinyl chloride, various condensed polymers such as polyurea, polyurethane, polyester, polycarbonate, and electrophotographic lithographic printing plate precursors Binders having high solubility in eluents used for e.g. styrene / maleic anhydride copolymers, styrene / maleic anhydride monoalkyl ester copolymers, (meth) acrylic acid /
(Meth) acrylic acid ester copolymer, styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer,
(Meth) acrylic acid such as vinyl acetate / crotonic acid copolymer, vinyl acetate / crotonic acid / (meth) acrylic acid ester copolymer, vinyl acetate / vinyl ester of carboxylic acid having 2 to 18 carbon atoms / crotonic acid Ester, styrene, vinyl acetate, etc. and (meth) acrylic acid, itaconic acid,
Copolymers with carboxylic acid-containing monomers such as crotonic acid, maleic acid, maleic anhydride, maleic anhydride monoalkyl ester, and fumaric acid, or with acid anhydride group-containing monomers, (meth) acrylamide, vinylpyrrolidone, phenolic A copolymer containing a monomer having a hydroxyl group, a sulfonic acid group, a sulfonamide group, a sulfonimide group, or the like can be given. In addition to this, Freche
“Journal of Imaging Sci.” Vol. 120, No. 2
No. 59-64, (1986), "Polymers
Polymers in E
electronics) (Symposium Ser)
ies) ", P11, 242, T.I. Davidson, E
d. , ACS Washington, DC (198
4) (Ito, Willson), and a binder used for a so-called “chemical amplification system” and a binder used for a positive or negative photosensitive layer. The addition amount of the binder can be used at about 0.1 to 5 g / m ² .

The laser-sensitive layer according to the present invention contains the above (a)
In addition to the infrared light absorbing agent and / or (b) a light absorbing agent having a wavelength capable of sensitizing the PS photosensitive layer and a binder, the dispersibility of the dispersion is improved, the laser recording sensitivity is improved, and the mechanical strength is improved. For this purpose, various additives can be used. For example, when a pigment is used as the infrared absorbing agent, a dispersing agent is used to disperse the pigment into fine particles so as not to aggregate. A wide range of such dispersants are commercially available. Suitable dispersants include ZENECA's superpigment dispersant Solsperse and H.I. K. Jakubauska
s. "Journal of Coating Technology (J. of Coating Technology)
y. ) P71-82, vol. 58, No. 736. "
And AB block polymers generally described in US Pat. Dispersants are generally used in amounts of 0.1 to 50% by weight, based on the pigment.

A plasticizer can be used to adjust the film forming characteristics of the binder. Such plasticizers include, for example, triphenyl phosphate,
Dithithimephthalate, diethyl phthalate, cyclohexylbenzyl phthalate, dibutoxyethyl adipate, ethylene glycol dibenzoate, glycerol acetate, polyethylene glycol monolaurate,
o, p-Toluenesulfonamide and the like. The amount of plasticizer is 1 to 30% by weight based on the binder.
In addition, various additives such as a surfactant are used as needed to improve coating properties.

The thickness of the laser light-sensitive layer is related to the sensitivity, and must be sufficiently thin to rapidly disappear and be removed during laser light irradiation. The laser light receiving layer can be formed as a thin layer on the PS photosensitive layer by vapor deposition of a metal, a metal oxide, an organic dye, or the like. The film thickness in this case is 50Å
It is 1000 °, preferably 100 ° to 500 °. The laser light-sensitive layer can be formed by coating together with an infrared light absorber, an active light absorber for the PS photosensitive layer, and a binder. In this case, the film thickness is 0.05 μm to 10 μm.
m, and preferably 0.1 μm to 5 μm.

In the method of making a lithographic printing plate precursor according to the present invention, first, this laser light-sensitive layer is image-exposed with visible to infrared laser light. It does not expose the photosensitive layer to light, and may be a gas laser such as an Ar laser or a carbon dioxide laser, a solid-state laser such as a YAG laser, or a semiconductor laser. Semiconductor lasers and semiconductor-pumped solid-state lasers (YAG lasers, etc.) are preferably used in terms of practicality such as an output of 50 mW class or more and maintainability and price. These recording wavelengths are in the infrared wavelength range, and are emission wavelengths of 800 nm to 1100 nm.

Next, the positive photosensitive layer or the negative photosensitive layer (PS photosensitive layer) used in combination with the laser light receiving layer and provided below the laser light receiving layer will be described in detail.

The PS photosensitive layer is formed by disposing a known photosensitive composition on a support such as an aluminum plate having a hydrophilic surface. The photosensitive composition constituting the PS photosensitive layer includes a positive photosensitive composition containing an o-quinonediazide compound as a main component, a diazonium salt and an alkali-soluble diazonium salt, and a light containing an unsaturated double bond-containing monomer as a main component. Depending on the purpose, one or more may be appropriately selected from a negative photosensitive composition using a polymerizable compound, a photocrosslinkable compound containing a cinnamic acid, a dimethylmaleimide group or the like as a photosensitive material, and the like.

The o-quinonediazide compound is generally used as a positive-type photosensitive composition for forming a positive-type photosensitive layer, and the o-naphthoquinonediazide compound which can be used is described in JP-B-43-28403. Esters of the described 1,2-diazonaphthoquinonesulfonic acids with pyrogallol-acetone resins are preferred. Other suitable o-quinonediazide compounds include, for example, esters of 1,2-diazonaphthoquinone-5-sulfonic acid and phenol-formaldehyde resin described in U.S. Patent Nos. 3,046,120 and 3,188,210. JP-A-2-96163, JP-A-2-9616
And esters of 1,2-diazonaphthoquinone-4-sulfonic acid and a phenol-formaldehyde resin described in JP-A-5-96671. Other useful o-naphthoquinonediazide compounds include those known in numerous patents and the like. For example, JP-A-47-5303 and JP-A-48-638.
No. 02, No. 48-63803, No. 48-96575
Nos. 49-38701, 48-13854, JP-B-37-18015, 41-11222, and 4
No. 5,961,610 and 49-17481, etc. can be mentioned.

Further, particularly preferred o-naphthoquinonediazide compounds include compounds obtained by reacting a polyhydroxy compound having a molecular weight of 1,000 or less with 1,2-diazonaphthoquinonesulfonic acid. Specific examples are described in JP-A-51-139402,
No. 58-150948, No. 58-203434, No. 59-165053, No. 60-112445, No. 6
0-134235, 60-16043, 61
-118744, 62-10645, 62-1
Nos. 0646, 62-153950, 62-178
Nos. 562 and 64-76047.

The amount of these positive-acting photosensitive compounds (including the above combinations) in the photosensitive composition constituting the PS photosensitive layer is suitably from 10 to 50% by weight, more preferably. Is from 15 to 40% by weight.

That is, although the o-quinonediazide compound alone can constitute the photosensitive layer, it is preferable to use a resin soluble in an alkaline solution as a binder from the viewpoint of the plate making process. As a resin soluble in such an alkaline solution, there is a novolak type resin, for example, phenol formaldehyde resin, o-,
m- and p-cresol formaldehyde resins, m /
p-mixed cresol formaldehyde resin, phenol / cresol (o-, m-, p-, m / p- and o /
m-mixing) and a mixed formaldehyde resin.

Further, a phenol-modified xylene resin, polyhydroxystyrene, polyhalogenated hydroxystyrene, and an acrylic resin containing a phenolic hydroxyl group as disclosed in JP-A-51-34711 can also be used.

Further, a polymer having an active imino group described in JP-A-63-226641 and JP-A-2-866.
Japanese Patent Application Laid-Open Nos. Hei 7-28244, Hei 7-36184, Hei 7-36185, Japanese Patent Application Nos. 6-52112 and 6
And copolymers having a molecular weight of usually 10,000 to 200,000 having various monomers as constituent units as described in JP-A-123895.

As other suitable binders, those described in JP-A-6-35184 can also be used.

The copolymer preferably contains unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid. The copolymer preferably has an acid value of 0 to 10 meq / g. Preferably 0.2 to 2
It is 5.0 meq / g.

The preferred molecular weight of the copolymer is 10,000 to 1
100,000. If necessary, a polyvinyl butyral resin, a polyurethane resin, a polyamide resin, and an epoxy resin may be added to the copolymer.

These alkali-soluble polymer compounds can be used alone or in combination of two or more, and are used in an amount of 80% or less of the total photosensitive composition.

Further, this photosensitive composition is added to US Pat.
As described in 4,123,279, a condensate of phenol and formaldehyde having a C3-8 alkyl group as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin, can be used in combination. This is preferable for improving the oil sensitivity of the image.

The photosensitive layer used in the present invention may be added to the photosensitive layer as long as the effects of the present invention are not impaired.
It is preferable to use known additives such as sensitizers, sensitizers, plasticizers, printing-out agents and image coloring agents as described in US Pat. Further, cyclic acid anhydrides, phenols, organic acids and higher alcohols can be added to enhance developability.

The positive photosensitive layer is formed by dissolving each of the above-mentioned components in a solvent capable of dissolving as a positive photosensitive composition, and then coating the solution on a support (generally, an aluminum plate). As the solvent used here, JP-A-62-25
An organic solvent as described in JP-A-1739 is used alone or as a mixture. The photosensitive composition is
It is dissolved and dispersed in a solvent at a solid content concentration of ５０50% by weight, coated on a support and dried.

The amount of the photosensitive composition layer (photosensitive layer) to be coated on the support varies depending on the application, but it is generally 0.3 to 4.0 g / m2 after drying. ² is preferred. As the amount of coating decreases, the amount of exposure for obtaining an image may be small, but the film strength is reduced. As the coating amount increases, the exposure amount is required but the photosensitive film becomes strong. For example, when used as a printing plate, a printing plate having a high printable number (high printing durability) can be obtained.

In the above-mentioned positive photosensitive composition, a surfactant for improving the coated surface quality, for example, JP-A-62-1
A fluorine-based surfactant as described in JP-A-70950 can be added. The preferable addition amount is 0.001 to 1.0%, more preferably 0.005 to 0.5% of the whole photosensitive composition.

Further, as the positive photosensitive layer of the PS plate, o-
Japanese Patent Application No. Sho 3-2, using no naphthoquinonediazide compound
59431, Japanese Patent Application No. 3-259433, and Japanese Patent Application Laid-Open No. 6-2.
A novel positive photosensitive layer utilizing a thermal crosslinking / acid hydrolysis reaction of vinyl ether or the like disclosed in No. 30574 or the like can also be used.

Next, the negative photosensitive layer will be described. Examples of the negative PS photosensitive composition constituting the negative PS photosensitive layer include a composition containing a photosensitive diazo compound, a photopolymerizable photosensitive composition, and a photocrosslinkable photosensitive composition.

Among these, a photocurable photosensitive copying material containing a photosensitive diazo compound and a photosensitive material having a photocrosslinkable photosensitive layer will be described.

As the photosensitive diazo compound, a diazo resin obtained by condensing an aromatic diazonium salt with a reactive carbonyl group-containing organic condensing agent, particularly an aldehyde such as formaldehyde or acetaldehyde or an acetal in an acidic medium is preferably used. . The most typical one is p-
There are condensates of diazophenylamine and formaldehyde. Further, JP-B-49-48,001, JP-A-4-18559, JP-A-4-190361 and JP-A-4-1361.
No. 72354, JP-A-3-2846, JP-A-3-5754
Nos. 3-240061, 3-253857, 4-172354, 4-221253, and 4-2
19759, 4-274429, 5-5984
Also, a photosensitive diazo compound described in JP-A No. 2000-163, etc. may be used.

The photosensitive diazo compound is preferably used in combination with a lipophilic polymer compound soluble or swellable in an alkaline solution as a binder. As such a lipophilic polymer compound, a copolymer having a molecular weight of usually 10,000 to 200,000 having the same monomer as that used in the above-mentioned positive photosensitive composition as a constitutional unit is exemplified. However, a polymer compound obtained by copolymerizing the following monomers as constituent units can also be used. For example, maleimide, N-acryloylacrylamide, N
-Acetylacrylamide, N-propionylacrylamide, N- (p-chlorobenzoyl) acrylamide, N-acetylacrylamide, N-acryloylmethacrylamide, N-acetylmethacrylamide, N-
Unsaturated imides such as propionyl methacrylamide and N- (p-chlorobenzoyl) methacrylamide;
A crosslinkable group is added to a side chain of [2- (acryloyloxy) -ethyl] -2,3-dimethylmaleimide, N- [2- (methacryloyloxy) -ethyl] -2,3-dimethylmaleimide, vinyl cinnamate, or the like. And the like.

Further, a monomer copolymerizable with the above monomer may be copolymerized. In addition, a copolymer obtained by copolymerization of the above-mentioned monomers modified with, for example, glycidyl acrylate or glycidyl methacrylate is also included, but is not limited thereto. The copolymer preferably contains unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid, and the copolymer preferably has an acid value of 0 to 1
0 meq / g, more preferably 0.2-5.0 meq / g.

The preferred molecular weight of the copolymer is 10,000 to 1
100,000. If necessary, a polyvinyl butyral resin, a polyurethane resin, a polyamide resin, and an epoxy resin may be added to the copolymer. Novolak type resins, phenol-modified xylene resins, polyhydroxystyrenes, polyhalogenated hydroxystyrenes, and alkali-soluble resins containing a phenolic hydroxyl group as disclosed in JP-A-51-34711 may also be used. it can.

These alkali-soluble polymer compounds can be used alone or in combination of two or more, and are usually contained in the range of 40 to 95% by weight in the solid content of the entire photosensitive composition.

As the photocrosslinkable polymer used in the photocrosslinkable photosensitive layer composition, a polymer having a maleimide group, a cinnamyl group, a cinnamoyl group, a cinnamylidene group, a cinnamylideneacetyl group, a chalcone group or the like in a side chain or a main chain is used. No.

As a polymer having a maleimide group in a side chain, JP-A-52-988 (corresponding to US Pat. No. 4,079,041)
No.), German Patent 2,626,769, European Patent
21,019, European Patent 3,552, and Die Angewandte Makromolekulare Chemie, Vol. 115 (1983), pp. 162-182, JP-A-50-501.
No. 97, No. 51-47940, No. 50-10884
And polymers having a maleimide group in the side chain described in JP-A Nos. 50-45087. The average molecular weight of these polymers is 1000 or more, preferably 30,000 to 40,000. Further, these polymers have an average of two or more maleimide groups per molecule in the side chain.

In order to make these polymers having a maleimide group in the side chain soluble or swellable in an alkaline solution, an acid group may be introduced into the polymer.

Specific examples of the acid group include carboxylic acid, sulfonic acid, phosphoric acid, and phosphonic acid, and alkali metal salts and ammonium salts thereof, and pK which is difficult to dissolve in alkaline water.
a is 6 to 12 acid groups, _{specifically,} -SO 2 NHCO
-, - CONHCO -, - SO 2 NHCOO-, and a 4-hydroxyphenyl group. The acid value of the maleimide polymer having an acid group is preferably in the range of 30 to 300,
More preferably, it is 50 to 200. Incidentally, preferred as a monomer having an acid group capable of copolymerization,
Examples thereof include vinyl monomers having a carboxyl group such as acrylic acid and methacrylic acid, maleic anhydride, and itaconic anhydride.

Among these polymers having an acid value,
Die Angewandte Makromolekulare Chemie 128
Copolymers such as those described in Vol. (1984), pp. 71-91 are useful.

Further, as a photosensitive compound that can be used here, there is also a photosensitive polyester described in US Pat. No. 3,030,208. As a product obtained by solubilizing these polymers in an alkaline solution, JP-A-60-19124
4, JP-A-62-175729, JP-A-62-17
5730, JP-A-63-25443, JP-A-63-
218944 and JP-A-63-218945 can be used.

The photocrosslinkable polymer used in the present invention has a molecular weight of 1,000 or more, preferably 10,000 to 50.
It is desirable to use a material having a size of 20,000, particularly preferably 20,000 to 300,000. The amount of the photocrosslinkable polymer to be added to the entire photosensitive layer composition is 10 to 99% by weight, preferably 50 to 99% by weight.
% By weight.

The photosensitive layer made of a photocrosslinkable polymer preferably contains a photosensitive diazo resin in order to improve the adhesion to a support. As such a photosensitive diazo resin, the aforementioned diazo resin can be used. The content when this diazo resin is contained in the photosensitive layer,
It is 0.1 to 30% by weight, preferably 1 to 10% by weight.

In the photosensitive layer used in the present invention, the photosensitive layer
Sensitizers as described in US Pat.
It is preferable to use known additives such as a sensitizer, a plasticizer, a printing-out agent and an image coloring agent. Further, cyclic acid anhydrides, phenols, organic acids and higher alcohols can be added to enhance developability.

The photosensitive composition of the present invention is applied to a support (for example, an aluminum plate) by dissolving the above components in a solvent that dissolves the above components. As the solvent used here, an organic solvent described in JP-A-62-251739 may be used alone or as a mixture. The negative photosensitive composition is dissolved and dispersed at a solid content of 2 to 50% by weight, coated on a support and dried.

The amount of the photosensitive composition (photosensitive layer) to be coated on the support varies depending on the application, but is generally from 0.3 to 4.0 g / m ^{2 in} terms of the weight after drying. preferable. As the amount of coating decreases, the amount of exposure for obtaining an image may be small, but the film strength is reduced. As the amount of application increases, the amount of exposure is required but the photosensitive film becomes stronger. For example, when used as a printing plate, a printing plate having a high printable number (high printing durability) can be obtained.

A surfactant for improving the coated surface quality can be added to the above-mentioned photosensitive composition, similarly to the positive photosensitive composition described above.

As the support of the lithographic printing plate precursor used in the plate making method of the present invention, a conductive substrate or the like which is a dimensionally stable plate-like material support is used. As such a support, a paper laminated with paper, plastics (eg, polyethylene, polypropylene, polystyrene, etc.), for example, a metal plate of aluminum (including aluminum alloy), zinc, iron, copper, etc. is used. ,
In particular, the effect of the present invention is remarkably exerted on a metal plate such as an aluminum plate. 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 thickness of the aluminum plate used is approximately 0.1
It is about mm to 0.6 mm.

In laminating the above-mentioned photosensitive layer on an aluminum plate as a support, it is preferable to roughen the aluminum plate in advance. A degreasing treatment with, for example, a surfactant, an organic solvent or an alkaline aqueous solution for removing impurities such as oil is performed. First, the surface of the aluminum plate is subjected to a surface roughening treatment, which includes a method of mechanically roughening the surface, a method of electrochemically dissolving the surface and a method of selectively dissolving the surface chemically. There is a way. As the mechanical method, a known method called a ball polishing method, a brush polishing method, a blast polishing method, a buff polishing method, or the like 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. Also, Japanese Patent Application Laid-Open No. 54-63902
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. H11-284, a method combining the two can also be used.

The aluminum plate thus roughened is subjected to an alkali etching treatment and a neutralization treatment as required, and then subjected to an anodic oxidation treatment if necessary to increase the water retention and abrasion resistance of the surface. You. As the electrolyte used for the anodizing treatment of the aluminum plate, any electrolyte that forms a porous oxide film can be used, and 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 conditions of the anodizing treatment vary depending on the electrolyte used and thus cannot be specified unconditionally. However, in general, 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 70%. It is appropriate that the voltage is 60 A / cm ² , the voltage is 1 to 100 V and the electrolysis time is 10 seconds to 5 minutes. The amount of the anodized film is suitably 1.0 g / m ² or more, but more preferably in the range of 2.0 to 6.0 g / m ^2. If 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 precursor is easily damaged, and the ink adheres to the damaged area during printing. So-called "scratch dirt" tends to occur. Although such anodizing treatment is performed on a surface used for printing of the support of lithographic printing plates, the back around the electric lines of force, 0.01 to 3 g / m ² on the back surface
Is generally formed. After the anodic oxidation treatment, the aluminum surface is subjected to a hydrophilic treatment if desired. U.S. Patent No.
There is a method using an alkali metal silicate (for example, an aqueous solution of sodium silicate) as disclosed in 2,714,066, 3,181,461, 3,280,734 and 3,902,734. In this method, the support is immersed or electrolytically treated in an aqueous solution of sodium silicate. In addition, potassium fluoride zirconate disclosed in JP-B-36-22063 and U.S. Pat.
No. 6,868, 4,153,461 and 4,689,272, for example, a method of treating with polyvinyl phosphonic acid is used.

Prior to such a hydrophilization treatment, a method of sealing the anodic oxide film with hot water or steam as described in JP-A-4-176690 may be performed.

In the lithographic printing plate precursor to which the method of the present invention is applied, an organic undercoat layer or an intermediate layer is provided before the photosensitive layer is coated on the aluminum substrate, if necessary. Examples of the organic compound used in the organic undercoat layer include carboxymethyl cellulose, dextrin, gum arabic, phosphonic acids having an amino group such as 2-aminoethylphosphonic acid, phenylphosphonic acid which may have a substituent, and naphthyl. Organic phosphonic acids such as phosphonic acid, alkylphosphonic acid glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, and organic phosphorus such as phenylphosphoric acid, naphthylphosphoric acid, alkylphosphoric acid and alkylglyceric acid which may have a substituent. Acids, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, organic phosphinic acids such as alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and triethanolamine hydrochloride and the like. Hydroxyl Although selected from such as hydrochloric acid salt of an amine with, it may be used as a mixture of two or more.

The coating amount of the organic undercoat layer after drying is from 2 to 20.
0 mg / m ² is suitable, preferably 5 to 100 mg / m ^2
2 If the coating amount is less than 2 mg / m ² , sufficient effects for the original purpose such as prevention of stain cannot be obtained. Also,
If it exceeds 200 mg / m ² , the printing durability will decrease. Further, an intermediate layer for improving the adhesion between the support and the photosensitive layer may be provided. In order to improve the adhesion, the intermediate layer is generally made of a diazo resin or a phosphate compound adsorbed on aluminum. The thickness of the intermediate layer is not particularly limited as long as it can perform a uniform bond-forming reaction with the upper photosensitive layer when exposed. Usually, about 1-100mg in dry application amount
/ Application rate of m ² is good, 5 to 40 mg / m ² is particularly favorable.

In the lithographic printing plate precursor according to the present invention,
Since an alkaline solution having a relatively high alkali strength is used as a developer, a support having a back coat layer may be used to suppress elution of aluminum oxide from the back surface. As such a back coat layer, for example, those described in detail in JP-A-5-45885, JP-A-5-210235 and JP-A-6-35174 can be used. Further, on the surface of the photosensitive layer provided as described above, in order to reduce the time of evacuation at the time of close contact exposure using a vacuum baking frame, and to prevent baking.
A mat layer may be provided. Specifically, JP-A-50-1
No. 25805, Japanese Patent Publication No. 57-6582, 61-28
Nos. 986 and JP-B-62-62337, but a lithographic plate having a mat layer which is soluble in a water-soluble and alkaline water developing solution is more preferable.

In the plate-making method of the present invention, a laser light-sensitive layer which is sensitive to visible to infrared laser light and which is insensitive to light having a wavelength capable of sensitizing a positive or negative photosensitive layer is used. In the first step of performing image exposure with visible to infrared laser light, the laser light energy used for image exposure is absorbed by the laser light sensitive layer and converted into heat energy, and the laser light sensitive property is ablated due to this. The material is expelled from the layer to form a recorded image.
In this step, the laser light receiving layer absorbs the laser light, but is insensitive to light having a wavelength capable of sensitizing the PS photosensitive layer laminated thereunder. It functions as a mask during the entire exposure process of the photosensitive layer.

Here, the whole surface exposure with light having a wavelength capable of sensitizing the positive or negative photosensitive layer is performed subsequently. The wavelength of light in this overall exposure is determined by the PS of the lithographic printing plate precursor.
Although it is selected according to the characteristics of the photosensitive composition forming the photosensitive layer, a metal halide lamp, a high-pressure mercury lamp, and the like are preferable.

By the whole-surface exposure in the second step, when the photosensitive layer is a positive type photosensitive layer, the irradiated portion becomes soluble in an alkaline aqueous solution, while when the photosensitive layer is a negative type photosensitive layer, the entire surface is exposed to light. In this case, the irradiated part becomes insoluble in the alkaline aqueous solution, and the non-irradiated part becomes soluble. Therefore, after the entire surface exposure, by performing a third step of treating the entire photosensitive layer with an alkaline solution, the alkaline solution-soluble portion of the photosensitive layer is removed, whereby a positive or negative type lithographic printing plate precursor is obtained. Plate making can be done.

Here, the eluate used in the elution step after the overall exposure will be described. The entire surface of the PS photosensitive layer is exposed, and in the case of the positive type, the solvent is irradiated with light. In the case of the negative type, any solvent is used as the eluent for removing the photosensitive layer in the non-irradiated part, as long as it can remove the photosensitive layer. Although possible and not particularly limited, an alkaline solution is usually used. The alkaline solution referred to here is an aqueous solution containing an alkaline compound, an organic solvent containing an alkaline compound, or a mixture of an aqueous solution containing an alkaline compound and an organic solvent.

Examples of the alkaline compound include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, potassium silicate, lithium silicate, sodium metasilicate, potassium metasilicate, sodium phosphate, potassium phosphate, ammonia, Examples thereof include any organic and inorganic alkaline compounds such as ethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, triisopropanolamine, diethylaminoethanol, and 2-amino-2-methylpropanol.

Among them, the general formula mSiO ₂ / nM
₂ O (M: alkali metal atom, m / n = 0.5-8.
By containing the silicate represented by 5) in the treatment liquid, it is possible to obtain better removability of the soluble portion and to make a lithographic printing plate precursor having good printing characteristics. .

Here, various kinds of organic solvents can be added to the alkaline solution using water as needed, as described above. Preferred organic solvents include methanol, ethanol, propanol, butanol, benzyl alcohol, lower alcohols and aromatic alcohols such as phenethyl alcohol and ethylene glycol, diethylene glycol, triethylene glycol, polyhydric alcohols such as polyethylene glycol, ether alcohols, Amino alcohols, ether esters,
Examples include ethers, ketones, and esters. Further, the alkaline solution may contain a surfactant, an antifoaming agent, and other various additives as required.

In the plate making method of the present invention, a washing step, a gumming step, a drying step, and a pattern recognition method provided with a CCD sensor and the like may be carried out as required after the elution step of removing the soluble portion of the PS photosensitive layer. A possible plate inspection step, a bender for processing a printing plate into a predetermined shape, a punching step, a plate stacking step, and the like can be provided.

[0077]

EXAMPLES The present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples.

(Example 1) Preparation of support A surface of an aluminum sheet conforming to JIS 1050 was grained with a rotating nylon brush using a pumice-water suspension as an abrasive. At this time, the surface roughness (center line average roughness) was 0.5 μm. After washing with water, it was immersed in a 10% aqueous solution of caustic soda at 70 ° C. to dissolve 6 g of aluminum.
and eluted as will become m ^2. After washing with water and immersing in a 30% nitric acid aqueous solution for 1 minute, the caustic soda was neutralized and sufficiently washed with water. Thereafter, electrolytic roughening is performed in a 0.7% nitric acid aqueous solution for 20 seconds using a short-wave alternating waveform having a voltage at the anode of 13 volts and a voltage of the cathode at 6 volts (described in Japanese Patent Publication No. 55-19191). The surface was washed by immersion in a 50% solution of 20% sulfuric acid, and then washed with water. Further, the substrate was subjected to anodizing treatment in a 20% sulfuric acid aqueous solution so that the weight of the anodized film became 3.0 g / m ² , washed with water, and dried to prepare a support.

Preparation of Positive Photosensitive Layer A positive photosensitive layer solution having the following composition was coated on the surface of the support with a bar coater and dried to form a positive photosensitive layer having a coating thickness of 2.0 g / m ² .

[Positive Photosensitive Layer Solution] 2.5 g of naphthoquinone-1,2-diazide (2) -5-sulfonic acid ester of acetone-pyrogallol resin (for the synthesis method, see Example 1 in US Pat. No. 363,570) Novolak-type cresol-formaldehyde resin 5.0 g Methyl ethyl ketone 75 g Cyclohexanone 60 g Preparation of laser light-sensitive layer The following mixture was dispersed for 30 minutes with a paint shaker, and then the glass beads were filtered off to prepare a carbon black dispersion. .

[Carbon black dispersion liquid]-Carbon black (# 40 manufactured by Mitsubishi Carbon Corporation) 5.0 g-Novolac-type cresol-formaldehyde resin 2.5 g-Solsperse S20000 (manufactured by ICI) 0.50 g-Solsperse S12000 (ICI) 0.25 g ・ Methyl ethyl ketone 45 g ・ Glass beads 160 g Next, using a carbon black dispersion, the following coating solution for a laser-sensitive layer was prepared, applied on the positive photosensitive layer, and dried with a laser beam having a thickness of 1 μm. A sensitive layer was formed. [Laser light-sensitive layer coating liquid] 55 g of the above carbon black dispersion 7.2 g of nitrocellulose (containing 30% of n-propanol) 45 g of methyl ethyl ketone

Formation of a lithographic printing plate The lithographic printing plate precursor thus obtained was subjected to a power of 110 mW, a wavelength of 825 nm, a beam diameter of 10 μm (1/1) on the plate surface.
using a semiconductor laser of e ^2), it was subjected to writing by the main operation speed of 6 m / sec, the laser recording sensitivity 20
At 0 mJ / cm ² , the resolution was 6 μm, and a recorded image with sharp edges was formed on the laser light sensitive layer. (First Step) Next, Fuji Photo Film Co., Ltd. A-3 printer (P
(S plate exposure machine) for 50 seconds. (Second Step) Subsequently, the above-exposed original plate was developed with a solution obtained by diluting DP-4 (developing solution made by Fuji Photo Film) 1: 8 with water (pH 13.1), and the lower layer of the recorded image area was developed. When the lithographic printing plate was prepared by eluting and removing the photosensitive layer (third step), a good lithographic printing plate having clear positive image portions and non-image portions free of stains was obtained. When this printing plate was used for printing with a sprint printing machine, 50,000 or more good prints free of printing stains were obtained.

Example 2 A lithographic printing plate was formed in the same manner as in Example 1 except that a binder having the following structure was used instead of the novolak type phenol resin used in Example 1, and a clear positive image was obtained. A good lithographic printing plate with no stains on the image and non-image areas was obtained. When this printing plate was used for printing with a sprint printing machine, 60,000 or more good prints free of printing stains were obtained.

(Example 3) A carbon black dispersion having the following formulation was dispersed on a support coated with the positive photosensitive layer obtained in Example 1 for 2 hours through a paint shaker, and adjusted. The same laser light receiving layer as described above was prepared and applied to form a laser light receiving layer having a dry film thickness of 1.5 μm.

[Carbon Black Dispersion] Microlith Black CA (Ciba-Geigy) 5.0 g Solsperse S20000 (ICI) 0.50 g Solsperse S12000 (ICI) 0.25 g Alcohol 45 g Glass beads 160 g When a lithographic printing plate was formed in the same manner as in Example 1,
A good lithographic printing plate free of clear positive image areas and non-image areas was obtained. When printing was performed by a sprint printer using this printing plate, 50,000 or more high-quality prints free of print stains were obtained.

(Example 4) Preparation of a support In the same manner as in the example, an aluminum plate was subjected to anodizing treatment, washed with water, then immersed in a 3% solution of sodium silicate at 70 ° C for 30 seconds, and washed with water. Example 1 except for drying
A support was prepared in exactly the same manner as described above. The aluminum support thus obtained had a reflection density of 0.30 and a center line average roughness of 0.40 μm.

Preparation of Negative-Type Photosensitive Layer Subsequently, a negative-type photosensitive layer solution having the following composition was applied by a bar coater and dried to prepare a negative-type photosensitive layer having a coating thickness of 1.9 g / m ² .

[Negative-type photosensitive layer solution] diazo resin; hexafluorophosphate of a condensate of p-diazodiphenylamine and valaformaldehyde 1.2 g (Synthesis example in JP-A-29-78403) 1) ・ Polyurethane resin; diphenylmethane diisocyanate / isophorone diisocyanate / 2-2-dimethylolpropionic acid / diethylene glycol (preparation ratio: 70/30/70/30 weight ratio) 5.0 g ・ Methyl ethyl ketone 60 g ・ 1-methoxy- Formation of 40 g of 2-propanol lithographic printing plate A laser-sensitive layer was provided on the negative photosensitive layer in exactly the same manner as in Example 1 to form a lithographic printing original plate. The lithographic printing original plate obtained in this manner was applied with a power of 110 m on the plate surface.
When writing was performed at a main operation speed of 4 m / sec using a semiconductor laser having a wavelength of 825 nm, a wavelength of 825 nm, and a beam diameter of 10 μm (1 / e ² ), the laser recording sensitivity was 150 mJ / sec.
cm ² , the resolution was 7 μm, and a recorded image with sharp edges was formed.

Next, the entire surface was exposed for 20 seconds using a 2KW metal halide lamp, developed with a solution of DN-3C (developing solution made by Fuji Photo Film) diluted 1: 1 with water, and the photosensitive layer other than the recorded image area was developed. Was eluted and removed to form a lithographic printing plate. As a result, a good lithographic printing plate having clear negative image areas and non-image areas with no stain was obtained. When this printing plate was used for printing with a sprint printing machine, 80,000 or more good prints free of printing stains were obtained.

(Example 5) After an aluminum support and a positive photosensitive layer were formed in the same manner as in Example 1, an infrared absorbing dye (IR-1) and a yellow dye (Y-
The following coating solution consisting of 1) was prepared and applied, and the dried film thickness was adjusted to 0.
A 7 μm laser sensitive layer was formed.

[Formulation of Coating Solution for Laser Sensitive Layer] 7 g of infrared absorbing dye (IR-1) 3 g of yellow dye (Y-1) 10 g of nitrocellulose (containing 30% of n-propanol) 65 g of methyl ethyl ketone

[0092]

Embedded image

Formation of a lithographic printing plate The lithographic printing plate precursor obtained in this manner was processed on the plate surface with a power of 130 mW, a wavelength of 825 nm, and a beam diameter of 10 μm (1/1).
e ² ) Writing was performed at a main operation speed of 4 m / sec using the semiconductor laser, and the sublimed dye was removed by an air stream. The laser recording sensitivity was 300 mJ / cm ² .
The resolution was 6 μm, and a recorded image with a sharp edge was formed on the laser sensitive layer.

Next, the entire surface was exposed for 50 seconds with an A-3 printer (PS plate exposure machine) manufactured by Fuji Photo Film Co., Ltd.
-4 (Developer made by Fuji Photo Film) was developed with a solution (pH 13.1) diluted 1: 8 with water to elute and remove the photosensitive layer below the recorded image area to form a lithographic printing plate. A good lithographic printing plate free of clear positive image areas and non-image areas was obtained. When this printing plate was used for printing with a sprint printing machine, 50,000 or more good prints free of printing stains were obtained.

[0095]

According to the present invention, a lithographic printing plate precursor having a sensitivity capable of forming a simple laser image, being capable of easily making a plate, and being applicable to a wide range of laser light sources, and having a simple processing step, A rapid and economical method of making a lithographic printing plate precursor could be provided. Further, in the method of making a lithographic printing plate precursor according to the present invention, a lithographic printing plate precursor having high resolution, excellent printing durability and excellent printing durability can be obtained by digital imaging means, and is stable against a light source such as room light. Thus, an excellent effect that processing can be performed in a completely light room was shown.

Claims (2)

[Claims] 1. A positive photosensitive layer or a negative photosensitive layer on a support having a hydrophilic surface, and a visible-to-infrared laser which is insensitive to light having a wavelength capable of sensitizing the photosensitive layer. A lithographic printing plate precursor comprising sequentially laminating laser light-sensitive layers which receive light and disappear. 2. A positive photosensitive layer or a negative photosensitive layer on a support having a hydrophilic surface, and a visible to infrared laser which is insensitive to light having a wavelength capable of sensitizing the photosensitive layer. A lithographic printing plate precursor obtained by sequentially laminating laser light-sensitive layers that receive light and disappear is image-exposed with visible to infrared laser light, and then the entire surface is exposed to light having a wavelength that can expose the photosensitive layer. A method of making a lithographic printing plate precursor, comprising: dissolving and removing an alkaline solution-soluble portion of the photosensitive layer with an alkaline solution.