JPS5818918B2 - Desensitizing liquid for lithographic printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a desensitizing liquid for lithographic printing plates, and more specifically, a desensitizing liquid for lithographic printing plates, which comprises a support, a photosensitive layer and a removable transparent cover film as essential components and are laminated in this order. This invention relates to a desensitizer suitable for peel-and-develop type photosensitive lithographic printing plates.

In recent years, research into the production of lithographic printing plates has become active.
The performance of manufactured lithographic printing plates has also been significantly improved, and in particular, the printing durability of printing plates has been dramatically improved, leading to a shift from letterpress plates to lithographic plates.

The reason for this situation is that recent lithographic printing plates have improved printing durability, making it possible to print in large quantities, and the workability when using them is also simple and good, and plate-making time is extremely short and development is fast. This is because it has various characteristics such as excellent stability and plate reproducibility, and can withstand long-term storage as a plate material.

Various types of lithographic printing plate materials have been known in the past, but those having the above-mentioned characteristics are made of photopolymerizable compositions (hereinafter abbreviated as photopolymers) as photosensitive layers.

) layer.

The photopolymers used in these printing plates include those whose main component is a photosensitive resin of a photoduplexing type, for example,
Polyesters of p-phenylene diacrylate and 1,4-cyclohexanediol described in Belgian Patent No. 696,533, and U.S. Pat. No. 3,38
7,976, a reaction product of a phenoxy resin and a cinnamic acid or a carboxylic acid having an unsaturated group higher than that, a polymerizable compound having an ethylenically unsaturated bond, and a binder (polymer) There are some whose main ingredients are

For example, the ethylenically unsaturated compounds described in U.S. Pat. No. 3,043,805, such as diethylene glycol diacrylate, triethylene glycol dimecacrylate, pentaerythritol
There are products whose main component is a photopolymerizable material represented by a combination of triacrylic acid ester, etc., and a binder material, such as a resin such as methyl methacrylate/methacrylic acid copolymer and styrene/itaconic acid copolymer. .

A photosensitive lithographic printing plate coated with these photopolymers is image-wise exposed through an original image having a desired negative pattern, and then developed with an appropriate developer such as an organic solvent or an alkaline aqueous solution. The areas hardened by the irradiation remain on the plate support, and the unexposed areas are dissolved and removed by the developer, so the pattern and halftone dots of the original for printing are formed on the plate support, becoming a lithographic printing plate. It is.

However, the above-mentioned solution or solvent-developed printing plate materials not only require complicated processing steps in that they require the use of a developer, but also require the use of alkaline solutions or organic solvents such as the developer. The use of chemical solutions is becoming extremely inconvenient from the standpoint of occupational health, danger, air pollution, and wastewater pollution.

In recent years, dry-developable recording materials have been proposed in place of such solution-developable printing plate materials.

Among these materials, those described in Japanese Patent Publication No. 38-9663, Japanese Patent Publication No. 43-22901, Japanese Patent Application Laid-Open No. 7728-1982, and Japanese Patent Application Laid-open No. 46315-1987 (1988-9663), Japanese Patent Publication No. 47-7728, and Japanese Patent Application Laid-open No. 46315-1988 (1988-9663), Japanese Patent Publications No. 43-22901, Japanese Patent Application Laid-open No. 46315-1983, etc. This method utilizes polymerizability and the resulting change in adhesive properties, and according to this method, a polymer as a binder, an unsaturated monomer, and a photopolymerization initiator are generally placed on a support such as a plastic film, metal, or paper. A layer of a photopolymerizable composition mainly composed of By exposing the photosensitive layer to light and peeling off the cover, one of the exposed and unexposed areas of the photosensitive layer is left on the support and the other is left on the cover, and a negative is placed on the support and the cover, respectively. and a positive (or positive and negative, respectively) image.

A release development type photosensitive material using such a photopolymerizable composition was used in a photosensitive lithographic printing plate, as disclosed in Japanese Patent Application Laid-Open No. 52-9.
No. 501 or JP-A-52-150104.

By the way, desensitization treatment in planographic printing plates is carried out in the case of plano intaglio plates and in the case of PS plates (Presensitized Pr1).
-nting P 1ate, which is abbreviation for lithographic printing plates that have been given photosensitivity in advance), is slightly different from the case of planar intaglio plates, in which the surface is leveled with acetic acid etc. before applying the photosensitive liquid, and after plate making, Etching with a mixed aqueous solution of gum arabic or desensitization treatment is performed with an aqueous solution of gum arabic alone.On the other hand, in the case of PS plates, the treatment is sometimes carried out to prevent reaction between the photosensitive layer and the aluminum surface. Alumite treatment, chemical conversion treatment with zirconium fluoride, or chemical conversion treatment with sodium silicate as described in US Pat. No. 2,714,066 is practically used.

Both PS plates and plano intaglio plates are treated before applying a photosensitive liquid, and in the case of PS plates, even after plate making, they are coated with gum arabic alone in an aqueous solution and made desensitized, just as in the case of plano intaglio plates. There are many cases where

The purpose of gumming in the desensitization process is not only to increase the hydrophilicity of the non-image areas of the printing plate, but also to preserve it after plate making until printing, or to preserve it until it is reused in the printing machine after it has been partially used. This is to prevent stains caused by the adhesion of fingerprints, oil, fat, dust, etc. that occur during handling, such as when mounting on a plate, and to protect from scratches, etc., and the most important of these is protection from scratches caused by the plate surface being directly exposed to the air. This is to prevent non-image areas from becoming dirty due to oxidation phenomena, etc.

However, gumming with the conventional desensitizing liquid (gumming liquid) as described above is not sufficiently suitable for release development type lithographic printing plates.

The reason for this is that when a peel development type lithographic printing plate is stored for a long period of time, after image exposure and peel development, numerous stain-like spots often appear in non-image areas.

This is because many peel-and-develop type photosensitive compositions contain ethylenically unsaturated monomers, hydrophobic liquid additives, etc.
When these compositions are applied to a hydrophilic support, over time, monomers, liquid additives, etc. penetrate into the grains and pores of the surface of the hydrophilic support for planography. And then,
It is thought that numerous speckled stains are produced on the surface of the hydrophilic support.

The non-printing area should originally be hydrophilic, but the non-printing area with such stains no longer shows hydrophilicity, and when printed, it causes a large amount of staining (overall staining). Cannot withstand use as a lithographic printing plate.

Next, in order to eliminate these drawbacks, JP-A-52-9
A method of providing a layer containing a hydrophilic organic polymer compound between a hydrophilic support and a layer of a photosensitive composition as described in No. 501, and as described in JP-A-52-150104. I tried treating the hydrophilic surface of the support with an aqueous solution of a specific water-soluble oxyacid or oxyacid, but
After peeling and development, a portion of the photosensitive composition remained in the non-image area, although it was an extremely thin layer, and it was difficult to completely eliminate this.

In recent years, there has been a demand for printing plates with high printing durability, and in order to further increase the printing durability of such peel-development type photosensitive lithographic printing plates, a method of irradiating the entire plate surface with actinic rays after image formation, so-called full-surface post-exposure ( or re-exposure of the entire surface).

The present inventors first discovered an effective post-exposure method in Japanese Patent Laid-open No. 5
No. 3-15906 proposed a method in which the plate surface of a printing plate after release development is irradiated with actinic light in the presence of oxygen while being heated.

Furthermore, Japanese Patent Application Laid-Open No. 54-12904 describes a gum solution (desensitizing solution) that does not cause stains even if it is gummed immediately after peeling development and post-exposure is performed.

However, it has been found that these desensitizing liquids lack stability over time, and their stain prevention effect deteriorates when the liquid is present for a long period of time or when the coating wave is applied for a long period of time.

An object of the present invention is to provide a desensitizing liquid that can be applied to a peel-developable photosensitive lithographic printing plate.

Another object of the present invention is to provide a desensitizing solution that does not cause stains even when post-processing (post-exposure, post-heating, etc.) is performed after plate making.

Still another object of the present invention is to provide a desensitizing liquid that has superior stability over time compared to conventional desensitizing liquids.

Still another object of the present invention is to provide a desensitizing liquid that has excellent stain removal ability and desensitizing effect not only on peel-development type R8 plates but also on all other lithographic printing plates. .

Still another object of the present invention is to provide a desensitizing solution that has both desensitizing and gumming functions.

As a result of extensive research in order to solve the above problems, the inventors of the present invention have found that the entire plate surface of a lithographic printing plate after peeling contains silicates, hydrophilic colloid substances, glycol ethers, and water as shown in the general formula. By applying a desensitizing liquid containing
After that, the entire plate surface is irradiated with active light, and the desensitizing solution does not cause any stains on the printing in non-image areas even after a long period of time until printing, and the anti-staining effect of the liquid does not deteriorate over time. They discovered that this can be obtained and arrived at the present invention.

(Here, M represents an alkali metal atom, B 1゜R2,
R3 and R4 each represent a hydrogen atom, an alkyl group or a hydroxyalkyl group, and may be the same or different from each other.

n is a number from 1 to 8.5, q is a number from 0 to 12, m is a number greater than 0 and up to 10, ppo 4 to 50
Each number represents a number up to 00.

), (2) a hydrophilic colloid substance, (3) a monoalkyl ether of ethylene glycol or polyethylene glycol, and (4) water.

The first component of the desensitizing liquid for lithographic printing plates of the present invention is a silicate generally represented by Inuyama, ('') or book, and these are:
It includes water-soluble particles and water-insoluble colloidal particles having an average particle size ranging from 5 nm to 300 nm.

In the desensitizing liquid, the first component imparts hydrophilicity to the lithographic printing plate surface, and on the other hand, imparts the property of accepting oil-based printing ink on the printed image, and also keeps the desensitizing liquid alkaline, thereby improving the lithographic printing. It imparts properties that prevent components of the photosensitive layer slightly remaining in non-image areas on the plate surface from being hardened by light, and is a basic component of the desensitizing liquid for lithographic printing plates of the present invention. .

In the general formula (1) and the marks, M represents an alkali metal atom, specific examples of which include lithium, sodium, potassium, rubidium and francium,
Preferred are lithium, sodium and potassium.

Next, general formula (II) and (in the dish, R1, R2,
R3 and R4 represent a hydrogen atom, an alkyl group or a hydroxyalkyl group.

The alkyl group represents a lower alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a pentyl group. Preferred are methyl and ethyl groups.

Hydroxyalkyl group represents a hydroxyalkyl group having 1 to 5 carbon atoms.

Specific examples include hydroxymethyl group, 2-hydroxyethyl group, 1-hydroxyethyl group, 3-hydroxypropyl group, 2-hydroxypropyl group, 4-hydroxybutyl group, 5-human waxypentyl group and 4-hydroxy -2-Methylbu.

Among these, hydroxymethyl, 2-hydroxyethyl and 1-hydroxyethyl are preferred.

Note that R1, R2, R3, and R4 may be different from each other or the same, but from the viewpoint of availability, price, etc., it is preferable that R1 to R4 are all the same.

Specific examples of the silicate represented by the general formula (I) include sodium silicate, lithium silicate, potassium silicate, rubidium silicate, and cesium silicate.

These silicates are used up to a ratio n of silica (silicon dioxide) to caustic oxide of about n = 8.5, but in the present invention, n is 1 or more, that is, 1≦n≦8. 5 can be used.

Specific examples of the silicate represented by the general formula (If) include:
L(CH3 N)20.(Si02)y.

[(CH3CH2.

Na2O.(Si02)y. L(HOCH2.

Na2O・(S t 02 ) y s[, (HOCH
2CH2±4N)20・(SiO2)y, and L(C
H3CH(OH)±4N') 2 ・< S+ 02
)y()・represents a number from 1 to 3.2.

) and the like described in JP-A-52-15702.

Specific examples of silicates represented by the general formula are I, 1
20・[(HOCH2CH2→4 N)20:12・
(Si02)20 and the like described in JP-A No. 49-97045 can be mentioned.

For the silicate represented by the general formula <III), either an aqueous solution or a sol using water as a dispersion medium can be used.

In the desensitizing liquid for lithographic printing plates of the present invention, the first component ranges from about 0.4% to about 40% by weight, preferably from about 2% to about 25% by weight of the total composition weight.

The second component of the desensitizing solution of the present invention is a hydrophilic colloid material.

In addition to acting as a binder for components other than water in the desensitizing liquid, hydrophilic colloid substances also impart hydrophilicity to lithographic printing plates, making them suitable for printing images receptive to oil-based inks and oil-based printing inks. It has a weak affinity and imparts the property of quickly removing the solid components in the desensitizing liquid from the printed image at the start of printing.

As a hydrophilic colloid substance, R., L.
Edited by Davidson, M. Sittig, IWa.
ter-8olable Re5ins j (Van
No5trand Relnhold, 196
Published in 1989, New York) and Special Publication No. 1973-509
The polymer compounds described in No. 3 and the like can be used.

Specific examples include cellulose derivatives such as methylcellulose, ethylcellulose, carboxymethylcellulose, carboxyethylcellulose, ethylhydroxyethylcellulose, ethylmethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose sodium salt, Carboxymethyl hydroxyethyl cellulose sodium salt, sodium cellulose sulfate, dextrin, shellac,
Alginate, polyvinylpyrrolidone, polyvinyl alcohol and its derivatives, polyacrylamide and its copolymers, acrylic acid copolymers, vinyl methyl ether/
Examples include maleic anhydride copolymer, vinyl acetate/maleic anhydride copolymer, styrene/maleic anhydride copolymer, and the like.

These substances can be used alone or in combination.

The content of the water-soluble colloidal material is from about 0.1% to about 20% by weight of the total composition weight of the desensitizing liquid of the present invention;
Preferably it ranges from about 0.4% to about 15% by weight.

The third component of the desensitizing liquid for lithographic printing of the present invention is.

It is a monoalkyl ether of ethylene glycol or polyethylene glycol.

This third component acts as the only solvent in the desensitizing solution and improves the permeability of the desensitizing solution into the plate, while also having the property of eluting the photosensitive composition remaining in the non-image areas. There is.

Examples of the monoalkyl ether of ethylene glycol or polyethylene glycol include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, and ethylene glycol monophenyl ether. ethylene glycol monoalkyl ether, diethylene glycol mono, □
Methyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monomethyl ether.

-thyl, triethylene glycol monoethyl ether,
Examples include monoalkyl ethers of polyethylene glycol such as triethylene glycol monobutyl ether.

The content of glycol ether is the insensitive fat of the present invention.

The amount ranges from about 0.1% to about 2.0%, preferably from about 1% to about 10% by weight of the total composition weight of the solution.

The fourth component of the desensitizing liquid for lithographic printing plates of the present invention is water.

Water functions as a solvent for the desensitizing liquid.

As water, distilled water, deionized water, water with solids removed by filtration, tap water, etc. can be used.

In the desensitizing liquid, water occupies the remainder of the content of other components, and although the range of its content is not specified, it is preferably about the weight of all the components of the desensitizing liquid. It ranges from 40% to about 90% by weight.

Also for lithographic printing of the present invention, it is preferable to add one or a combination of two or more compounds selected from the group consisting of anionic surfactant and polyhydroxyalkane to the sensitizing liquid. .

These components provide good spreading characteristics when the desensitizing liquid is applied to the lithographic printing plate surface, appropriately suppress drying, sustain the hydrophilic effect, prevent the adhesion of stains, and At the start of printing, the desensitizing liquid has properties that allow components other than water to be easily removed from the printed image by the oil-based printing ink.

The nonionic surfactant or polyhydroxyalkane that can be used in the present invention is a water-soluble compound, and more preferably has hygroscopic properties itself.

Specific examples include polyalkylene glycols, polyethylene glycol alkyl ethers, polyethylene glycol alkyl phenyl ethers, polyethylene glycol esters, trivalent or higher polyalkanols, phosphoric acid esters of alkanols, and phosphoric acid esters of monohydroxy ethers. etc.

As polyalkylene glycols, the general formula HO (-C
z H2z O+ a H (z is an integer from 1 to 6,
a represents an integer from 1 to 500.

), specific examples of which are:
Ethylene glycol, propylene glycol, butylene glycol, bentanediol, hexylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol,
triethylene glycol, tetraethylene glycol,
dipropylene glycol, tripropylene glycol,
Examples include polyethylene glycol.

As polyethylene glycol alkyl ethers,
It includes monoethers and diethers, the degree of polymerization of ethylene glycol ranges from about 5 to about 30, and the alkyl group includes those having from 12 to 25 carbon atoms.

Polyethylene glycol alkylphenyl ethers include monoethers and diethers, the degree of polymerization of ethylene glycol ranges from about 5 to about 30, and the alkylphenyl group has 1 to 1 carbon atoms.
Up to two alkyl groups can substitute the phenyl group.

As a specific example, polyethylene glycol p-(6-
methylhephthyl) Hue.

Nyl ether, nonylphenyl ether, octylphenoxypolyethoxyethanol can be used.

Polyethylene glycose esters include monoesters and diesters, the degree of polymerization of ethylene glycol is in the range from about 5 to about 30, and the fatty acid forming the ester is a saturated fatty acid having from 12 to 30 carbon atoms. I can do it.

Specific examples of trivalent or higher polyalkanols include glycerin, sorbitol, pentaerythritol, diglycerin, and dipenta.

Erythritol, tripentaerythritol, etc. can be mentioned.

Specific examples of phosphoric esters of alkanols include phosphoric esters of hexanol, occuenol, and decanol.

Specific examples of monohydroxy ethers such as nisdityl phosphate include phosphoric acid esters of 2-octyloxyethanol and 2-decyloxyethanol.

Among these, trivalent or higher polyalkanols or polyalkylene glycols are preferred, and particularly preferred compounds are Shiba ethylene glycol, diethylene glycol, propylene glycol, hexamethylene glycol,
These include glycerin, sorbitol, and pentaerythritol.

Nonionic surfactant that can be used in the present invention.

The content of the sexing agent or polyhydroxyalkanes is from about 3% to about 30% by weight of the total composition weight of the desensitizing liquid;
Preferably it is within the range of about 7% by weight to about 20 parts by weight.

Next, the desensitizing liquid for lithographic printing of the present invention includes the following.

It is preferable to add an anionic surfactant to increase the solubility of the solvent (glycol ethers) and water.

Examples of anionic surfactants include aliphatic salts, higher alcohol sulfate ester salts, aliphatic alcohol phosphate ester salts, sulfonate salts of dibasic fatty acid esters,
Aliphatic amide sulfonates, alkylaryl sulfonates, alkyl esters of sulfo fatty acids, formaldehyde condensed nacculin sulfonates, and the like are used.

Among these, naphthalene sulfonic acid formalin condensate is preferred.

The anionic surfactant is about 0% of the total composition weight of the desensitizing liquid.
．． It ranges from 1% by weight to about 20 parts by weight, preferably from about 1 part to about 10 parts by weight.

Acetate can be added to the desensitizing liquid for lithographic printing of the present invention in order to prevent staining of non-image areas.

Specific examples include sodium acetate, potassium acetate,
Examples include calcium acetate, magnesium acetate, ammonium acetate, and zinc acetate.

Among them, sodium acetate and potassium acetate are preferred.

The desensitizing liquid for lithographic printing plates of the present invention may further contain, if necessary, a compound selected from the group consisting of molybdic acid, boric acid, nitric acid, phosphoric acid, polyphosphoric acid, and water-soluble alkali metal salts and ammonium salts thereof. At least one kind can be added.

These components have the function of preventing background smearing of the desensitizing liquid and the function of strengthening, maintaining, and enhancing the hydrophilicity of the non-image areas of the lithographic printing plate, and are in addition to other components contained in the desensitizing liquid. It is necessary to use a material that does not react with the compound to form a precipitate or cause phenomena such as gelation.

It has been found that the above-mentioned acids, their water-soluble alkali metal salts, or their water-soluble alkali metal salts do not cause such a phenomenon.

Specific examples of compounds that can be added for these purposes include the following.

Salts of molybdate include lithium molybdate, sodium molybdate, potassium molybdate, ammonium hebucmolybdate ((NH4)6MO□0□4
・4H20), sodium phosphomolyfdate (Na3po
4+1.2Mo03), ammonium phosphomolybdate (
(NH4)3PO4・12M0O3・3H20), etc. As a borate, lithium metaborate (L + BO2
・2H20), lithium tetraborate (L 12B40□
・5H20), lithium metaborate (NaBO2), sodium tetraborate (Na 2 B+ 07 ・1OH
20), Sodium decaborate (Na2 B+0016
"10H20), sodium perborate (NaEO□, H2
0□.

3H2o), boric acid) IJium hydrogen peroxide adduct (N
a2B40□・H2O2・9H20), sodium boroformate (Na H2BO3・2 HCOOH・2 H20
), potassium metaborate (KBO2), potassium tetraborate (K2B40.・5H20), ammonium tetraborate ((NH4)2 B4.0□・4H20), ammonium bisulfate ((NH4)HB40□・3H20), etc.
Phosphates include sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, sodium pyrophosphate, potassium pyrophosphate, sodium metaphosphate, potassium metaphosphate, sodium polymetaphosphate, and polyphosphate. Examples of the nitrate include sodium phosphate, sodium polyphosphate, and potassium polyphosphate. Examples of the nitrate include lithium nitrate, sodium nitrate, potassium nitrate, and ammonium nitrate.

These acids, water-soluble alkali metal salts thereof, or water-soluble alkali metal salts thereof are used in an amount of from about 0.011% to about 10 parts by weight based on the total composition weight of the desensitizing liquid of the present invention, preferably A range of about 0.2% to about 5% by weight can be used.

Next, the present invention will be explained in more detail based on examples.

Example 1 and Comparative Example 1 A 28-material aluminum plate for lithographic printing plates (99% aluminum, 0.5% magnesium) grained by a mechanical method.
6% silicon and 0.4% silicon)
The surface was partially corroded by immersion for 1 minute in a 2% by weight sulfur-IJium hydroxide aqueous solution maintained at 0°C.

After washing with water, it was immersed in a sulfuric acid-chromic acid mixture for about 1 minute to expose the pure aluminum surface, and then kept at 30°C.
% sulfuric acid solution, DC voltage 15V, current density 3
A, Anodization treatment was performed for 2 minutes under condition 1 of /dm.

Then, it was immersed for 90 seconds in an aqueous sodium molybdate solution with a concentration of 200% by weight and a temperature of 65° C., and then dried.

On the other hand, the following composition was mixed with methyl ethyl ketone 100゜/
A solution of the photosensitive composition was prepared by dissolving the photosensitive composition in a mixed solution of 20 m/dimethylformamide and dimethylformamide.

Chlorinated polyethylene (manufactured by Yamaba Kokusaku Pulp ■, Superchlon CPE-907LTA)
*10! j.

Pentaerythritol tri-methacrylic acid ester 10 g2-methylanthraquinone 02g hydroquinone
0.1g Copper phthalocyanine pigment 0.2g (*Superchron CPE-907LTA is 40 parts by weight of 2 parts by weight of luene solution)
The compound has a viscosity of about 90 cps at 5°C and a chlorine content of over 666% by weight.

) This photosensitive solution was coated on the previously prepared aluminum plate surface using a spin coating machine (the thickness of the photosensitive layer after removing the solvent was 4 μm), and after drying at 80°C for 7 minutes, the photosensitive solution was coated on the photosensitive layer. A photosensitive lithographic printing plate was prepared by laminating a polyethylene terephthalate film having a thickness of 12 μm under pressure.

After that, the photosensitive lithographic printing plate was passed through a negative film,
1 at a distance of 1m using a metal halide lamp (2KW).
Image exposure was performed for 7 seconds.

When the polyethylene terephthalate film was immediately removed, a photocured positive image was formed on the aluminum plate, while the uncured parts (unexposed parts) were removed together with the polyethylene terephthalate film.

This lithographic printing plate was then divided into eight plates, each of which was gummed with the following desensitizing liquid.

(8) Desensitizing liquid (C1) to (C4) or (C6) to (C9
), the nine samples gummed by
000~1450μW/c1? L) Conveyed at a speed of 30 mm and 1 second while irradiating the entire surface.

The nine samples obtained in this way were left under natural conditions for 7 days, and then printed after aging.
In the plate treated in (C4), stains occurred in the non-print areas, but in the plates treated in (C5) to (C9), stains in the non-print areas did not occur.

Example 2 A 38 material aluminum plate (aluminum alloy plate made of 98.8% manganese 1.2 aluminum) for planography was
70 to remove and clean oil adhering to the surface during rolling.
It was treated by immersing it in an aqueous solution of 5% sodium tertiary phosphate at 50°C for 5 minutes.

This treatment caused some etching and increased water retention.

After washing with water, this was immersed in a 70% nitric acid solution, thoroughly washed with water, grained with carborundum, and washed with water.

This aluminum plate was anodized for 2 minutes at a current density of 3 A/dm in a 20% sulfuric acid aqueous solution at 50°C, washed and dried, and then immersed in a 1% phosphoric acid aqueous solution at 70°C for 2 minutes. After washing with water, 0.1 of polyvinylpyrrolid:/(K-30) [manufactured by Tokyo Kasei T-gyo ■] was applied using a spin coater.
% aqueous solution was applied and dried.

On the other hand, the following composition was mixed with 100 m of 1,2-dichloroethane.
/ and 40 ml of monochlorobenzene to prepare a solution of the photosensitive composition.

Chlorinated polyethylene (manufactured by Sanyo Kokusaku Pulp■, (5uperch, ron) CPE-907LTA)*8g Pentaerythritol trimethacrylate]0g 2-methylanthraquinone 0.2. @Hydroquinone 0.1g Copper phthalocyanine pigment 0.2g Epiol G
100 (main component glycerin triglycidether, specific gravity 1.23 at 20°C, manufactured by NOF ■), 0.02g (*Superchron CPE-907LTA has a viscosity of 40% by weight toluene solution at 25°C of approximately 90 Cp)
s, and the chlorine content is 66 parts by weight.

This solution was coated on a polyethylene terephthalate film with a thickness of 12 μm and dried at 80° C. for 10 minutes.

The thickness of the photosensitive layer after drying was 4 μm. Then, it was laminated under pressure onto an aluminum plate that had been surface-treated and undercoated with a hydrophilic polymer compound.

The image to be printed on this photosensitive lithographic printing plate material was brought into close contact with a polyethylene terephthalate film, and the image and polyethylene terephthalate film were passed through it using a PS Light S type (metal halide lamp, 2 kVl) manufactured by Fuji Photo Film Co., Ltd., for 1 m. Image exposure was performed for 20 seconds from a distance of .

When the polyethylene terephthalate film is immediately removed after that, a photocured positive image (printable image) is formed on the aluminum plate, and the uncured areas (unexposed areas) are
It was removed together with the polyethylene terephthalate film to obtain a lithographic printing plate.

Next, this lithographic printing plate was divided into nine samples, each containing the desensitizing liquids (Cl) to (C4) used in Example 1.
(C5) to (C0) were applied.

However, this desensitizing solution was left in a container for two months under natural conditions.

The gummed sample was subjected to post-exposure and printed in the same manner as in Example 1, and stains occurred in the non-image areas in the plates treated in (C1) to (C4), but in (C5) to (C0). In the treated plate, no stains occurred in the non-image areas.

Claims (1)

[Claims] 1(1) General formula M2O・(SiO2)n-qH20(
I) (Here, M represents an alkali metal atom. Rl. R2, R3 and R4 each represent a hydrogen atom, an alkyl group or a hydroxyalkyl group, and may be equal to or different from each other. n is 1 to 8 .5, q is a number from 0 to 12, m is a number greater than 0 and up to 10, p is a number from 4 to 50.
Each number represents a number up to 00. ), (2) a hydrophilic colloid substance, (3) a monoalkyl ether of ethylene glycol or polyethylene glycol, and (4) water.