JPH0659520A - Original plate for planographic printing - Google Patents

Abstract

PURPOSE:To stably form the planographic printing plate which is improved in effect of preventing side etching, allows printing with a high grade and has excellent gradation reproducibility and color reproducibility by coating the surface of a conductive base with a photosensitive layer contg. specific compds. CONSTITUTION:This original plate for planographic printing is constituted by coating the surface of a conductive base with the photosensitive layer contg. photoconductive pigments and o-naphthoquinone diazide sulfonate of polyhydroxybenzophenone. The photoconductive pigments to be used are exemplified by various org. or inorg. photoconductive pigments and the more specific org. photoconductive compds. are exemplified by perylene pigments, quinacridone pigments, phthalocyanine pigments, etc. The inorg. photoconductive pigments are exemplified by zinc oxide, titanium oxide, etc. Org. photosemiconductors of a pigment system are more preferable in terms of photosensitivity, safe light characteristic and thermal stability. Above all, phthalocyanine pigments and more particularly epsilon type phthalocyanine pigments are preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a photosensitive layer containing a photoconductive substance and a photosensitive substance whose solubility in an eluent used for elution is changed by a photochemical reaction on a conductive support. The present invention relates to a lithographic printing plate precursor in which a toner image is formed on a photosensitive layer by an electrophotographic method, and then the whole surface is exposed to light and subjected to an elution treatment to prepare a lithographic printing plate.

[0002]

2. Description of the Related Art Conventionally, as a method of preparing a lithographic printing plate using an electrophotographic method, after forming a toner image on the photoconductive layer of a lithographic printing plate precursor having a photoconductive layer on a support, There is known a technique for producing a lithographic printing plate by removing a photoconductive layer in a portion having no toner layer by elution development.

However, in the above technique, during the elution process, the eluent permeates from the photoconductive layer in the non-image area to the photoconductive layer located under the image area, that is, the toner image, and the area is removed. The so-called side-etching occurs, which is a drawback that the image reproducibility and stability are poor. That is,
Due to the progress of side etching, characters and fine lines became thin, gradation reproducibility was lowered in halftone dot photographic originals, and it was difficult to perform subtle reproduction required for highlight and shadow. Also,
Color printing lacked the ability to reproduce colors. In addition, fluctuations in the elution process, which are mainly caused by fluctuations in the activity of the eluate, affect side etching, making it difficult to manufacture a printing plate of a certain quality. Further, when side etching is suppressed in order to improve the image reproducibility, there is a problem in that the elution failure in which the components of the photosensitive layer remain in the non-image area is likely to occur, and stains are likely to occur in printing.

As a technique for improving such drawbacks, a lithographic printing plate precursor having a photoconductive layer containing a photosensitive substance is disclosed in British Patent No. 996,315, JP-A-57-90648, and JP-A-58-1509.
It is known by No. 53 and No. 60-194467. These lithographic printing plate precursors form a toner image by an electrophotographic method on a photosensitive layer containing a photoconductive substance and a quinonediazide compound, and eluate the entire surface of the photosensitive layer through the toner image. The solubility of the photosensitive layer with respect to is changed imagewise, and then elution development is performed to obtain a lithographic printing plate.

[0005]

However, the known techniques for incorporating these quinonediazide compounds into the photoconductive layer do not have sufficient side-etch preventing effect, and the side-etch problem described above remains. In particular, the ability of gradation reproduction and color reproduction was insufficient for high-quality printing. Furthermore, it is difficult to obtain a printing plate of stable quality, and when suppressing side etching, there remains a problem that stains are likely to occur. In addition, there is a problem that the electrophotographic sensitivity such as photosensitivity is not sufficient.
Increasing the content of the photoconductive substance to improve the electrophotographic sensitivity increases the irradiation time of the active light to the quinonediazide compound, leading to the prolongation of the plate making time, or the photosensitive layer component in the photoimage area remains and the printing There was a drawback that it caused stains. Furthermore, the above-mentioned technique has a defect that the latitude of elution development is narrow (a defect that the elution characteristics are likely to change due to a change in activity of the eluate, and a defect that is weak in over-development and under-development).

Therefore, the first object of the present invention is to improve the side-etch preventing effect in a lithographic printing plate precursor having a photosensitive layer containing a photoconductive substance and a photosensitive substance on a conductive support. It is to provide a lithographic printing plate precursor capable of stably producing a lithographic printing plate excellent in gradation reproduction and color reproduction capable of high-quality printing. Secondly, a lithographic printing plate precursor having improved electrophotographic characteristics. Is to provide the third
To provide a lithographic printing plate precursor in which printing stains of the obtained lithographic printing plate are prevented, and both the printing stains and the side-etching prevention effect are excellent, and fourth, lithographic printing in which the plate making time is shortened. The fifth is to provide a lithographic printing original plate in which the latitude of elution development is expanded.

[0007]

The above object of the present invention is to provide a lithographic plate comprising a conductive support and a photosensitive layer containing a photoconductive pigment and an o-naphthoquinonediazide sulfonic acid ester of polyhydroxybenzophenone. Achieved by the printing plate.

The present invention will be described in detail below.

As the photoconductive pigment used in the present invention, various organic or inorganic photoconductive pigments can be mentioned. Among them, organic photoconductive compounds are preferable. As specific organic photoconductive compounds, perylene pigments described in JP-A-47-30330 and 56-5552, quinacridone pigments described in JP-A-47-30331, JP-A-47-18543 Bisbenzimidazole pigments described in JP-A-47-18544 and JP-A-55-987
No. 54, No. 55-126254, No. 55-163543 aromatic polycondensed ring compounds described in JP-B-44-16373, 48-30513,
Azo pigments described in JP-A-56-321465, JP-B-50-
7434, JP-A-47-37548, JP-A-55-11715, JP-A-56-1944
No. 56-9752, No. 56-2352, No. 56-80050, etc., disazo pigments described in JP-B-44-12671, 40-2780.
Nos. 52-1667, 46-30035, 49-17535, JP-A-49-11136, 49-99142, 51-109841, 57-14
Examples thereof include phthalocyanine pigments described in Japanese Patent No. 8745, and these can be used alone or in combination of two or more kinds.

Examples of the inorganic photoconductive pigment that can be used in the present invention include zinc oxide and titanium oxide.

In the present invention, the photoconductive substance is preferably a pigment-based organic photo-semiconductor from the viewpoints of photosensitivity, safelight property and thermal stability, and among them, a phthalocyanine pigment,
Particularly, ε-type phthalocyanine pigment is preferable.

The content of the photoconductive substance is preferably 3 to.
It is 50%, more preferably 5 to 20%. It is preferable to increase the content in order to improve the electrophotographic sensitivity and suppress the residual potential, but on the contrary, after the elution, the photosensitive layer components are likely to remain on the non-image area support, which causes stains during printing. Occurs.
Further, in order to shorten the elution time and the post-exposure time, it is better to control the content. By adding the amount of the quinonediazide compound, since the effect of improving the electrophotographic sensitivity can be obtained, as a result, the content of the photoconductive substance is suppressed, stains in printing are prevented, elution time and post-exposure time. The effect of shortening can be obtained.

Further, in the present invention, a photoconductive substance other than the photoconductive pigment can be used in combination.

Next, o-naphthoquinonediazide sulfonic acid ester of polyhydroxybenzophenone used in the present invention (hereinafter referred to as "quinonediazide compound of the present invention")
Will be described.

The following are specific examples of polyhydroxybenzophenone that forms an ester bond with o-naphthoquinonediazide sulfonic acid.

2,2'-dihydroxybenzophenone, 2,3-
Dihydroxybenzophenone, 3,4-dihydroxybenzophenone, 3,3'-dihydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 3,4,5-trihydroxybenzophenone, 3,
4,4'-trihydroxybenzophenone, 2,3,5-trihydroxybenzophenone, 3,4,6-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone,
3,4,5,4'-Tetrahydroxybenzophenone, 2,3,4,5-
Tetrahydroxybenzophenone.

The polyhydroxybenzophenone used in the present invention is preferably 2,3,4-trihydroxybenzophenone, 3,4,5-trihydroxybenzophenone and 2,3,4,4 '.
-Tetrahydroxybenzophenone.

Combines with polyhydroxybenzophenone
The o-naphthoquinone diazide sulfonic acid is preferably o-naphthoquinone diazide-4-sulfonic acid or o-naphthoquinone diazide-5-sulfonic acid, of which o-naphthoquinone diazide-4-sulfonic acid is preferred.

The condensation rate of o-naphthoquinonediazide sulfonic acid with respect to the hydroxy group of polyhydroxybenzophenone (reaction rate with respect to one —OH group) is preferably 30 to 100%, more preferably 70 to 100%.

The quinonediazide compounds of the present invention may be used alone or in combination of two or more.

In the photosensitive layer of the present invention, the content of o-naphthoquinonediazide sulfonate of polyhydroxybenzophenone is preferably in the range of 0.4 × 10 ^{-3 to} 3 × 10 ^-3 mol / g. If it is less than 0.4 × 10 ^-3 mol / g, the effect of suppressing side etching is insufficient, and if it exceeds 3 × 10 ^-3 mol / g, dark attenuation and fogging become large.

The photosensitive layer according to the present invention preferably contains an alkali-soluble resin as a binder resin. In order to prevent printing stains, it is preferable that the alkali-soluble resin contains 10% or more of a novolac resin.

The novolac resin is a copolycondensate of phenols and an active carbonyl compound, and the phenols include all compounds in which at least one hydrogen atom bonded to an aromatic ring is substituted with a hydroxyl group. Specifically, for example, phenol, o-cresol, m-cresol, p-cresol, 3,5-xylenol, 2,4-xylenol, 2,5-
Examples include xylenol, carvacrol, thymol, catechol, resorcin, hydroquinone, pyrogallol, phloroglucin, or alkyl group (having 1 to 8 carbon atoms) substituted phenol, preferably phenol, o-
Cresol, m-cresol and p-cresol.

The active carbonyl compound includes, for example, aldehydes and ketones, and specific examples thereof include formaldehyde, acetaldehyde, benzaldehyde, acrolein, furfural and acetone.

Specific examples of the novolac resin include, for example,
Phenol / m-cresol / formaldehyde copolycondensate resin, o-cresol / m-cresol / formaldehyde copolycondensate resin, m-cresol / p-cresol / formaldehyde copolycondensate resin, o-cresol / m-cresol Preferred are / p-cresol / formaldehyde copolycondensate resin, phenol / m-cresol / p-cresol / formaldehyde copolycondensate resin, and the like.

Of the above copolycondensate resins, phenol /
Particularly preferred is m-cresol / p-cresol formaldehyde resin. The ratio of phenol (mixing ratio) in the resin is preferably 0 to 50% by weight, more preferably 5 to 30% by weight, and the ratio of m-cresol and p-cresol is 3: 7 to 7: 3. The range of (charged weight ratio) is preferable.

The above novolak resins may be used alone or in combination of two or more.

The novolak resin preferably has a number average molecular weight (Mn) of 3.00 × 10 ² (polystyrene standard).
〜7.50 × 10 ³ , weight average molecular weight (Mw) 1.00 × 10 ³ 〜3.
00 × 10 ⁴ , more preferably Mn of 5.00 × 10 ^{2 to} 4.00 × 1
0 ³ and Mw are values within the range of 3.00 × 10 ^{3 to} 2.00 × 10 ⁴ .

The molecular weight of such a novolak resin is measured by GPC (gel permeation chromatography method). The number average molecular weight Mn and the weight average molecular weight Mw are calculated by averaging the peaks in the oligomer region by the method described in Morio Tsuge, Tatsuya Miyabayashi, and Masayuki Tanaka, "Journal of the Chemical Society of Japan," pages 800-805 (1972). (Connect the center of the peak and the valley).

As a method for confirming the amount ratio of the phenols used in the synthesis of the novolak resin, pyrolysis-gaschromatograph (Pyrolysis-gaschromatograph) is used.
y, PGC) is used. Regarding pyrolysis gas chromatography, its principle, equipment and experimental conditions are, for example,
The Chemical Society of Japan, Shin Tsuge, “New Experimental Chemistry Lecture”, Volume 19, Polymer Chemistry [I], pages 474 to 485 (published by Maruzen 1978), etc., of novolac resin by pyrolysis gas chromatography. The qualitative analysis method is based on the method described in Morio Tsuge, Takashi Tanaka, and Masayuki Tanaka, "Analytical Chemistry," Vol. 18, pp. 47-52 (1969).

The content of the novolak resin in the photosensitive layer of the present invention is preferably 5 to 70% by weight, more preferably 20 to
50% by weight.

As the binder resin, in addition to the above, for example, a copolymer of styrene and maleic anhydride, a copolymer of styrene and monoalkyl maleic anhydride, a methacrylic acid / methacrylic acid ester copolymer, styrene /
Methacrylic acid copolymer, styrene / methacrylic acid / methacrylic acid ester copolymer, acrylic acid / methacrylic acid ester copolymer, styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer,
Acrylic acid such as vinyl acetate / crotonic acid / methacrylic acid copolymer, acrylic acid such as methacrylic acid ester, styrene, vinyl acetate, methacrylic acid,
Copolymers with carboxylic acid-containing monomers such as itaconic acid, crotonic acid, maleic acid, maleic anhydride and fumaric acid, or copolymers with acid anhydride group-containing monomers, methacrylamide, vinylpyrrolidone, phenolic hydroxyl groups, sulfonic acid groups, sulfonamides A vinyl acetal resin such as a copolymer containing a monomer having a group or a sulfonimide group, a phenol resin, a partially saponified vinyl acetate resin, a xylene resin, or a polyvinyl butyral can be used.

A copolymer containing a monomer having an acid anhydride group or a carboxylic acid group as a copolymerization component and a phenol resin are preferable from the viewpoint of good charge retention of the photoconductive layer and other electrophotographic characteristics.

The copolymer containing a monomer having an acid anhydride group as a copolymerization component is preferably a copolymer of styrene and maleic anhydride. Further, a half ester of this copolymer can also be used. As a copolymer containing a monomer having a carboxylic acid group as a copolymerization component, there is a binary copolymer of acrylic acid or methacrylic acid and an alkyl ester, an aryl ester or an aralkyl ester of acrylic acid or methacrylic acid. preferable. Further, vinyl acetate and crotonic acid copolymer, and terpolymer of vinyl acetate and vinyl ester of carboxylic acid having 2 to 18 carbon atoms and crotonic acid are also preferable examples.

The conductive support of the lithographic printing plate precursor of the present invention includes an aluminum plate, a resin laminated with aluminum, or a zinc plate, a copper-aluminum plate, a copper-plate.
Bimetal plate such as stainless steel plate, chrome-copper plate, or chrome-copper-aluminum plate, chrome-lead-iron plate, chrome-
A conductive support having a hydrophilic surface such as a trimetal plate such as a copper-stainless plate is used.

Further, particularly in the case of a support having an aluminum surface, the surface is subjected to degreasing treatment, graining treatment, anodizing treatment, dipping treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate or the like. It is preferably treated.

The graining treatment includes mechanical graining such as ball polishing, brush polishing and blasting, and electrochemical graining in a hydrochloric acid or nitric acid electrolytic solution by an AC or DC electric field. Can be applied.

The anodizing treatment may be carried out by using an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid or nitric acid, an organic acid such as oxalic acid or sulfamic acid, or an aqueous solution or a non-aqueous solution of these salts, or a combination of two or more thereof. It is carried out by passing an electric current in an electrolytic solution using an aluminum plate as an anode.
The amount of anodized film is 0.1 to 10, preferably 1 to 5 g / m ² .

Further, after the anodic oxidation, it is preferable to carry out a dipping treatment with an aqueous solution of an organic acid, an inorganic acid or a salt thereof. Organic acids include formic acid, acetic acid, propionic acid,
Oleic acid, succinic acid, lactic acid, tartaric acid, citric acid, benzoic acid, glutamic acid, sulfamic acid, sulfinic acid,
Examples thereof include barbituric acid, and inorganic acids such as sulfuric acid and
Examples thereof include nitric acid, nitrous acid, silicic acid and oxalic acid. As the salt, an alkali metal salt such as sodium or potassium or an ammonium salt is preferably used. The immersion treatment is 0.
The treatment is carried out in an aqueous solution having a concentration of 001 to 10% by weight, preferably 0.1 to 1% by weight, under a temperature environment of 50 to 200 ° C., preferably 80 to 150 ° C., for 5 seconds to 3 minutes.

Further, silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective. The treatment with polyvinyl sulfonic acid described in West German Patent Publication No. 1621478 is also suitable.

These hydrophilic treatments are carried out to prevent the harmful reaction with the photosensitive layer provided thereon and after elution, except for the purpose of making the components of the photosensitive layer, except that the surface of the support is rendered hydrophilic. It is applied in order to prevent residual and to improve the adhesion to the photosensitive layer.

Further, in the present invention, casein, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, phenol resin, styrene-maleic anhydride copolymer, polyacrylic acid and the like are optionally provided between the conductive support and the photosensitive layer. An alkali-soluble intermediate layer can be provided for the purpose of improving the adhesion between the support and the photosensitive layer.

In addition, to the lithographic printing plate precursor of the present invention, known techniques for a lithographic printing plate precursor having a photosensitive layer containing a photoconductive substance and a quinonediazide compound on a conductive support can be applied. Examples of such known techniques include dye sensitizers, chemical sensitizers, plasticizers, and overcoat layers described in JP-A-59-170862.

To produce the lithographic printing plate precursor of the present invention,
The photosensitive layer components mainly containing the photoconductive pigment, the quinonediazide compound and the binder resin can be mixed in an organic solvent and then uniformly dispersed by a ball mill, an ultrasonic disperser or the like.

In the present invention, the following organic solvents can be used as the solvent or dispersion medium used for preparing the coating liquid for coating the photosensitive layer.

Alcohols such as propanol, butanol, amyl alcohol, hexanol and cyclohexanol; ketones such as methyl ethyl ketone, acetone, cyclohexanone, methyl propyl ketone and methyl inbutyl ketone; esters such as methyl lactate, ethyl lactate and butyl acetate; Ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether,
With polyhydric alcohols such as ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, diethylene glycol methyl ethyl mater, diethylene glycol dimethyl ether Derivatives containing their ethers or acetates; tetrahydrofuran, dioxane.

The obtained photoconductive composition (photosensitive solution) is coated on a conductive support to a thickness of preferably 1 to 10 μm, more preferably 1 to 5 μm, and dried, and if necessary, heat treated. Obtained. As a coating method, known methods such as wire bar, dip, blade, reverse roll, air knife, and extrusion can be used.

To prepare a lithographic printing plate using the lithographic printing plate precursor of the present invention, a toner image is formed on the lithographic printing plate precursor by an electrophotographic method, and then a quinonediazide compound actinic light is applied to the lithographic printing plate precursor. The photosensitive layer in the image area is removed using an alkaline etching solution.

Developer (toner) used in electrophotography
Is desirably hydrophobic and ink receptive,
For example, polystyrene resin, polyester resin (amino group-containing acrylic ester, long-chain acrylic ester, etc.), acrylic resin (resin having phenolic hydroxyl group or sulfo group) epoxy resin, vegetable oil modified alkyd, cyclized rubber, asphalt, Includes polymeric substances such as vinyl chloride. Further, a colorant such as carbon black, a nigrosine pigment, carmine 6B, phthalocyanine blue, benzidine yellow, phthalocyanine green or an ultraviolet absorber may be contained within a range that does not adversely affect the granulation property of the toner, and charge control is further performed. Agents such as metal salts of fatty acids and naphthenic acids, metal-containing pigments, sulfonates and the like can be contained.

From the viewpoint of resolution, it is common to use a liquid toner dispersed in an insulating carrier liquid as the toner used for plate making. The transmission density of the quinonediazide active light in the toner image area is 0.5 or more, preferably 0.8 or more.

Regarding the liquid toner, JP-A-57-210345
57, 210-346, 57-210346, 58-194040,
58-194041, 60-6954, 61-36759, 62-353
The toner disclosed in No. 70 etc. can be used.

The present invention also works effectively with a dry toner used in a general PPC (plain paper copying machine).

After the toner image is formed as described above, the entire surface is exposed to the quinonediazide compound with active light from a halogen lamp, a xenon lamp, a mercury lamp or the like to enhance the solubility of the non-image area in the etching solution. After that, etching treatment is performed.

The etching treatment method is not particularly limited. For example, a so-called new liquid supply method described in Japanese Patent Application No. 1-168641 and shower circulation supply as described in JP-A-58-25477. Method or Japanese Patent Application No. 2-32010, Japanese Patent Application No. 2-9
The immersion treatment method as described in 6773 can be applied.

The etching solution used is not particularly limited and may contain an alkali agent, an organic solvent, a surfactant, a chelating agent, etc., for example, Japanese Patent Application Nos. 2-32010 and 3-2.
The etching solution described in 03374 etc. can be used.

After the etching treatment is completed, washing or rinsing treatment may be conducted, and then gumming treatment may be conducted.

The toner in the image area may be removed after the entire surface exposure with the active light of the quinonediazide compound. The toner removal step can be provided before or after the elution or between any steps of the elution step including the steps of etching, washing with water, rinsing, gumming and the like.

As a method of removing toner, Japanese Patent Application No. 3-2451
The methods described in No. 05, JP-A-56-66863 and JP-A-56-130766 can be used.

For the rinse treatment and gumming treatment, reference can be made to JP-A-63-271256, Japanese Patent Application No. 1-215314, and the like. Further, the techniques of rinse treatment and gumming treatment disclosed in the treatment of positive and negative PS plates can be used as they are.

[0060]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Examples 1 to 11 and Comparative Examples 1 to 7 Aluminum plates (JIS1100) having a thickness of 0.30 mm were degreased with an aqueous solution of caustic soda, and then subjected to a current density in an aqueous solution of hydrochloric acid of 0.3 mol / l (30 ° C.). Electrolytic polishing surface roughening treatment was performed for 30 seconds by an alternating current of 50 A / dm ² . Next, desmut treatment is performed in a 5% caustic soda aqueous solution at 60 ° C for 10 seconds, and further, in a 20% sulfuric acid solution at 20 ° C at a current density of 3 A / dm ² , 1
It was anodized for a minute and washed with water. After treatment, hot water (80
(° C) for 30 seconds and dried with warm air to obtain an aluminum support for a lithographic printing plate precursor.

Subsequently, the coating solutions for the photosensitive layers having the compositions shown in Tables 1 and 2 were dispersed in a sand grinder for 3 hours, and then coated on the support with a wire bar, at 90 ° C. for 3 minutes at 55 ° C. 48
After drying for a period of time, lithographic printing plate precursors of Examples 1 to 11 and Comparative Examples 1 to 7 were obtained. The coated photosensitive layer thickness is 40 mg.
It was / dm ² .

The compounds used in Examples 1 to 11 and Comparative Examples 1 to 7 will be described below. The compound N is added before the compound name.
The compound No. is shown in Tables 1 and 2 by adding o.
Further, in the table, the numbers in parentheses represent "parts by weight". Moreover, Mw represents a weight average molecular weight.

Photoconductive substance OPC-1 ε type copper phthalocyanine (Toyo Ink Co., Ltd.)
"Liophoton-EK") OPC-2 2,5-bis (4-diethylaminophenyl) oxadiazole OPC-3

[0065]

[Chemical 1]

OPC-4

[0067]

[Chemical 2]

OPC-5

[0069]

[Chemical 3]

OPC-6

[0071]

[Chemical 4]

Photosensitive Compound QD-1 2,3,4-trihydroxybenzophenone-naphthoquinone (1,2) -diazide (2) -5-sulfonic acid triester QD-2 2,3,4-trihydroxybenzophenone- Naphthoquinone (1,2) -diazide (2) -4-sulfonic acid triester QD-3 2,3,4-trihydroxybenzophenone-naphthoquinone (1,2) -diazide (2) -4-sulfonic acid diester QD- 4 p-Cresol-formaldehyde polycondensation novolak resin (Mw2000) o-naphthoquinonediazide-4-sulfonic acid ester compound (esterification rate 33%) QD-5 Pyrogallolacetone resin (Mw2000) o-naphthoquinonediazide-4-sulfone Acid ester compound (esterification rate 30%) Binder resin B-1 Phenol / m-cresol / p-cresol / formaldehyde polycondensation novolak resin (mixing ratio = 1)
0:50:40 (weight ratio)) B-2 poly-p-hydroxystyrene (Mw 20000) B-3 benzyl methacrylate / methacrylic acid / methyl methacrylate copolymer (polymerization ratio = 5: 3: 2, Mw 20000) B- 4 Hydroxyphenyl methacrylamide / acrylonitrile / methyl methacrylate / ethyl acrylate copolymer (polymerization ratio = 30: 35: 5, Mw 20000) B-5 Styrene / methacrylic acid copolymer (polymerization ratio = 7:
3) Solvent S-1 Ethyl cellosolve S-2 Methyl ethyl ketone

[0073]

[Table 1]

[0074]

[Table 2]

The lithographic printing plate precursors of Examples 1 to 11 and Comparative Examples 1 to 7 described above were evaluated as follows.

Electrophotographic characteristics: Sensitivity and dark decay were measured using SP-428 manufactured by Kawaguchi Electric Co., Ltd. The results are shown in Table 2. In Table 2, the sensitivity is indicated by the half-exposure amount (lux · sec) of the light attenuation from the initial potential of 200V, and the dark attenuation is the attenuation in the dark from the initial potential of 200V by the least squares method.
It was approximated to the (-kt) curve and indicated by the coefficient k. In each case, the smaller value is preferable.

Printing characteristics: For each lithographic printing plate precursor,
Plate making was performed by the following method. With a scorotron,
After being charged to a plate surface potential of +200 V, exposure was performed with a semiconductor laser having an output of 3 mW at a scanning speed of 250 m / sec to form an electrostatic latent image. Immediately after that, the liquid was developed using the liquid developing device disclosed in Japanese Examined Patent Publication No. 2-19952, dried, and then dried.
Thermal fixing was performed at ℃ for 10 seconds. The developing time was 7 seconds.

The liquid developer was prepared as follows.

Octadecyl methacrylate / methacrylic acid copolymer (copolymerization ratio 90:10) 1 part by weight Isopar G (Exxon) 5 parts by weight MA-100 (carbon black, Mitsubishi Kasei) 1 part by weight was dispersed with glass beads for 5 hours. Then, a solution of 1 part by weight of polyethylene (average molecular weight of 2000, Sanyo Kasei Sun Wax 151P) and 4 parts by weight of Isopar G was added and further dispersed for 10 hours. This solution was diluted with Isopar G so that the solid content concentration became 0.3% by weight and used. After forming a toner image on the lithographic printing plate precursor in this way, it is irradiated with ultraviolet rays in a total amount of 4 J / cm ² from a mercury lamp, and a non-image area photosensitive layer is formed using the apparatus described in JP-A-58-74566. Was eluted.

As the eluate, Examples 1 to 11 were produced by Konica Corporation.
A positive PS plate developing solution SDR-1 diluted 6 times with water was used. The liquid temperature was 27 ° C. and the supply rate was 15 l / m ² .

In Comparative Examples 1 to 7, an eluate having the following composition (A) containing a large amount of an organic solvent was used because the photosensitive layer could not be removed at all with a 6-fold dilution of SDR-1.

Composition of Eluate (A) Isopropanol 25 parts by weight A Potassium silicate 3 parts by weight KOH 50% aqueous solution 1 part by weight Triethanolamine 1 part by weight Water 70 parts by weight Other elution conditions are the same as in Examples 1 to 11. is there.

After the elution, the first rinsing, the second rinsing, and gumming were performed to obtain a lithographic printing plate.

The lithographic printing plate characteristics of the obtained lithographic printing plate were evaluated as follows.

Side etch: Side etching progress width (width of contraction of the photosensitive layer with respect to the toner image) was measured for the elution times of the developing solutions of 15, 30, 45 and 60 seconds, and the measured values were plotted. It is shown as a side etch progress width (μm) per second of elution time when the slope is approximated by a linear expression.

Print stain: A printed matter was prepared and the occurrence of print stain was visually determined.

◎ No print stains ○ Slight print stains △ Print stains occurred Elution: The minimum time required for elution under the above elution conditions was measured.

The above results are shown in Table 3.

[0089]

[Table 3]

Table 4 below shows the elution time and the side etch progress rate when the lithographic printing plate precursors of Example 2 and Comparative Examples 6 and 7 were treated with the SDR-1 8-fold dilution solution and 4-fold dilution solution. Show.

[0091]

[Table 4]

As is clear from these results, in the lithographic printing plate precursor of the present invention, compared with other o-quinonediazide compounds,
The latitude can be expanded for fluctuations in the eluate.

[0093]

According to the present invention, in a lithographic printing plate precursor having a photosensitive layer containing a photoconductive substance and a quinonediazide compound on a conductive support, the side-etch preventing effect is improved and high-quality printing is possible. It is possible to stably create a lithographic printing plate with excellent gradation and color reproduction, improve electrophotographic characteristics, prevent printing stains on the resulting lithographic printing plate, reduce plate making time, and reduce the latitude of elution development. The effect of expanding is obtained.

Claims (1)

[Claims] 1. A lithographic printing plate precursor comprising a photoconductive layer containing a photoconductive pigment and an o-naphthoquinonediazide sulfonate of polyhydroxybenzophenone coated on a conductive support.