JPS6262341B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plate-making method for a lithographic printing plate, and in particular, it relates to a method for making a lithographic printing plate, and in particular, a process for forming a non-image area (which receives dampening water during printing) from a photosensitive lithographic printing plate in which a photosensitive layer is provided on a metal support. The present invention relates to a plate-making method capable of obtaining a lithographic printing plate with less so-called stains in which oil-based ink adheres to regions (areas that repel oil-based ink for lithographic printing).

Conventionally, a photosensitive printing plate with a photosensitive layer provided on a metal support such as an aluminum plate having a hydrophilic surface is imagewise exposed, and then either the exposed or unexposed portions of the photosensitive layer are removed by development and supported. A plate making method is known in which a lithographic printing plate is obtained by exposing the hydrophilic surface of the body, in which the area where the hydrophilic surface is exposed is a non-image area, and the remaining area is an image area.

The surface of the above-mentioned metal support is coated with mechanical, chemical, or electrochemical graining, oxyacid acid, etc., with the main purpose of improving the adhesion of the image area and the water retention and hydrophilicity of the non-image area. chemical conversion treatment with solution;
The surface is usually roughened by various methods such as anodizing. Although this surface roughening improves the adhesion between the image area and the support, it also has the disadvantage that the non-image area becomes easily stained. This is because lipophilic substances such as components constituting the photosensitive layer have penetrated deep into the recesses of the roughened surface of the metal support (e.g., pits formed by graining or pores in the anodized film). This is because it cannot be completely removed even by development.

As a method for preventing the staining of planographic printing plates as described above, as disclosed in Japanese Patent Application Laid-Open No. 49-32703, a photosensitive planographic printing plate using a grained aluminum plate as a support is subjected to image exposure. A known method is to develop a lithographic printing plate, which is used as an anode and electrolyzed in an aqueous solution of a water-soluble oxyacid such as sodium silicate to form a hydrophilic film in the non-image area. However, the lithographic printing plate thus obtained still had the drawback that non-image areas were smeared.

Therefore, an object of the present invention is to provide a plate-making method capable of obtaining a lithographic printing plate with less staining in non-image areas from a photosensitive lithographic printing plate.

Another object of the present invention is to provide an improved plate-making method capable of obtaining a lithographic printing plate with less staining from a photosensitive lithographic printing plate using a roughened metal support.

The inventors of the present invention have conducted intensive research to achieve the above object, and as a result, they have completed the present invention. A photosensitive lithographic printing plate having a photosensitive layer on the roughened surface is imagewise exposed and developed to remove either the exposed portion or the unexposed portion of the photosensitive layer in the imagewise exposure to form the roughened surface. After exposure, calcium hydroxide, calcium carbonate, aluminum oxide,
This is a method for making a lithographic printing plate, characterized in that it is filled with at least one hydrophilic fine particle selected from titanium oxide and silicon oxide. Furthermore, the present inventors imagewise exposed a photosensitive lithographic printing plate having a photosensitive layer on the roughened surface of a metal support having a hydrophilic roughened surface, and developed the image of the photosensitive layer. After removing either the exposed portion or the unexposed portion during exposure to expose the roughened surface,
In a method for making a lithographic printing plate in which the exposed roughened surface is filled with at least one hydrophilic fine particle selected from calcium hydroxide, calcium carbonate, aluminum oxide, titanium oxide and silicon oxide, the hydrophilic fine particles are A method characterized in that the filling is carried out by applying an emulsion of an aqueous phase containing suspended hydrophilic fine particles and an oil phase consisting of a lipophilic substance to the exposed roughened surface. It has been found that the above objectives can be achieved more effectively.

The present invention will be explained in more detail below.

The photosensitive lithographic printing plate used in the plate-making method of the present invention is composed of a metal support having a hydrophilic roughened surface and a photosensitive layer provided on the roughened surface. Here, the hydrophilic surface refers to a surface that receives dampening water and repels oil-based ink used during lithographic printing.

Examples of the metal support include plates of metals such as aluminum, zinc, and iron, and plastic sheets laminated with foils or sheets of the above metals. Among these, aluminum plates are particularly preferred.

The surface of such a metal support must be roughened. In the present invention, surface roughening includes mechanical or electrochemical graining, chemical etching, anodizing, and a combination of two or more of these treatments. Any treatment method well known in the art can be used for such surface roughening, and the roughened surface obtained by such treatment is hydrophilic.

Preferred examples of metal supports with hydrophilic roughened surfaces include mechanically grained aluminum plates immersed in an aqueous sodium silicate solution as described in U.S. Pat. No. 2,714,066;
Aluminum plate anodized as described in U.S. Pat. No. 3,181,461 and then immersed in an aqueous alkali metal silicate solution; anodized in phosphoric acid as described in U.S. Pat. No. 3,511,661; Oxidized Aluminum Plate, US Patent No.
After anodizing in sulfuric acid as described in GB 3808000, an aluminum plate immersed in phosphoric acid, AC electrolyzed in hydrochloric acid as described in GB 1208224, and then immersed in sulfuric acid. These include anodized aluminum plates, aluminum plates electrolyzed with special waveform alternating current in hydrochloric acid or nitric acid as described in U.S. Pat. No. 4,087,341. Another preferred example is a support in which an undercoat layer of a water-soluble resin such as gelatin, hydroxyethyl cellulose, carboxymethyl cellulose, or polyvinylpyrrolidone is further provided on the roughened surface of an aluminum plate roughened as described above. be.

For the photosensitive layer provided on such a roughened aluminum plate, any photosensitive composition suitable for making lithographic printing plates can be used, for example as described in British Patent No. 1,350,521. British patent no.
A photosensitive layer made of a mixture of a diazo resin and a polymer containing 2-hydroxyethyl acrylate units or 2-hydroxyethyl methacrylate units as a main repeating unit, as described in the specifications of No. 1460978 and No. 1505739; Tokukai Akira
A photosensitive layer made of an o-quinonediazide compound and a novolak type phenol resin described in Japanese Patent No. 50-125806, a photosensitive layer made of a photocrosslinkable photopolymer disclosed in US Pat. No. 3,860,426, and a US patent 4072528 and British Patent No. 4072527, a photosensitive layer of a photopolymerizable composition as described in British Patent No. 1235281 and British Patent No. 4072527;
It includes a photosensitive layer made of a mixture of an azide compound and a water-soluble polymer compound described in each specification of No. 1495861, and a photosensitive silver halide emulsion layer.

The effect of the plate-making method of the present invention is better exhibited when the non-image area of the lithographic printing plate obtained by exposing and developing a photosensitive lithographic printing plate is easily smudged, and such lithographic printing Specific examples of plates include coating a photopolymerizable composition on a roughened aluminum plate, such as those described in U.S. Pat. No. 3,353,955, U.S. Pat. A photosensitive lithographic printing plate is provided with a plastic film transparent to the photosensitive layer and the active light in this order. After image exposure is carried out through the plastic film, the plastic film is peeled off under heating if necessary, thereby exposing the exposed portions of the photosensitive layer and the active light. A lithographic printing plate obtained by a so-called peeling phenomenon in which one of the unexposed areas is removed together with the plastic film, and a photosensitive lithographic printing plate in which a photosensitive silver halide emulsion layer is provided on a roughened aluminum plate. It includes a lithographic printing plate obtained by imagewise exposing the lithographic printing plate, followed by tanning development and washing out with hot water to remove the emulsion layer that was not hardened by the tanning development, and in particular, the plate-making method of the present invention for the latter lithographic printing plate. The effect is remarkable and is the most preferred embodiment.
For details and improvements of the photosensitive lithographic printing plate having the above photosensitive silver halide emulsion layer, please refer to JP-A-Sho.
No. 52-154626, No. 52-154626, No. 53-10422
No. 53-19205, No. 53-46802 and No. 53-
Since it is described in each publication of No. 1357027, you can refer to these.

Imagewise exposing the photosensitive lithographic printing plate as described above,
The roughened surface of the lithographic printing plate obtained by developing and removing either the exposed area or the unexposed area of the photosensitive layer and exposing the roughened surface of the support corresponding to that area. At least one hydrophilic fine particle selected from calcium hydroxide, calcium carbonate, aluminum oxide, titanium oxide, and silicon oxide is filled. Here, the term aluminum oxide is meant to include alumina sol, and the term silicon oxide is meant to include silica sol. Such fine particles are filled to block the lipophilic substances existing in the recesses of the roughened surface, thereby suppressing stains caused by the lipophilic substances, and therefore, the particles must be sufficiently fine to fill the recesses. No. Specifically, fine particles having a particle size smaller than the diameter of the entrance of the recess are used. Therefore, the particle size of the fine particles is selected depending on the roughness of the roughened metal support, but is generally about 2 mμ to about 50 mμ, preferably 5 mμ to 20 mμ.
selected from those having a particle size of For example, the pores of an alumite film obtained by anodizing an aluminum plate in phosphoric acid have a diameter of about 30 mμ, so by using silica sol with a particle size of 5 to 20 mμ, SiO ₂ can be filled.

Although the fine particles may have various shapes such as spherical or rod-like, spherical particles exhibit the effects of the present invention better. This is thought to be because spherical particles can more easily enter the recesses on the roughened surface.

Fine particles that can be used in the present invention are commercially available. Each of the following particles is advantageous for use because particularly fine particles can be obtained.
Ultrafine particle anhydrous aluminum oxide (2~40mμ, manufactured by Nippon Aerosil), ultrafine particle anhydrous silica (7~40μ)
mμ, same as above), ultrafine titanium oxide (2 to 50 m
μ, same as above), ultrafine calcium carbonate (20-80m
μ, manufactured by Shiraishi Kogyo, Maruya Calcium), silica sol (10-20 mμ, manufactured by Nissan Chemical), composite or modified silica sol (Ludotux AM manufactured by DuPont, particle size approximately 15
mμ), alumina sol (diameter 10mμ, length 50-100
mμ, same as above), etc.

Conveniently, the microparticles are loaded onto the roughened surface using a dispersion in an aqueous medium. in this case,
Preferably, those that do not aggregate or gel easily.

The concentration of the fine particles is about 1% to about 20% by weight, more preferably 2% to 10% by weight based on the total weight of the dispersion.
Weight%.

The fine particle dispersion is applied to the roughened surface of the lithographic printing plate by dipping, coating, or the like. Furthermore, when charged fine particles are used, the charge can be taken into account so that the fine particles can be more effectively filled into the recesses of the roughened surface. For example, the inner surface of the pores in the anodic oxide film of an aluminum plate often has a positive or negative charge due to the adsorption of electrolyte components and the presence of aluminum hydroxide. The sign of the charge changes depending on the conditions for forming the oxide film, the passage of time, the adsorption of coexisting substances, etc., but whether it is positive or negative can be determined by measuring the zeta potential. More effective filling can also be achieved by selecting particles that have an opposite charge to the inner surface of the pore.

In addition to the method of immersing in a dispersion of fine particles,
It is also effective to apply a roughened surface by impregnating a sponge with a fine particle dispersion such as a silica sol or alumina sol and rubbing it.

As mentioned above, when filling the roughened surface of the support with fine particles using an aqueous dispersion of fine particles, even if the fine particles directly adhere to the oil-sensitive substance present in the recesses of the roughened surface, Alternatively, the effects of the present invention can be obtained even if the particles are deposited so as to close the vicinity of the entrance of the hole. However, it has been found that it may also deposit in the image area and reduce the oil sensitivity. In order to overcome these drawbacks, the present inventors have conducted further research and found that by using an emulsion of an aqueous phase containing a suspended hydrophilic particulate substance and an oil phase consisting of a lipophilic substance, the image area can be improved. It has been found that staining of non-image areas can be effectively suppressed without reducing the oil sensitivity of the image.

The hydrophilic fine particles used in the present invention are selected from calcium hydroxide, calcium carbonate, aluminum oxide, titanium oxide, silicon oxide, etc. as described above, and among these, particularly preferred are calcium hydroxide, alumina sol, and silica sol. The effect of the invention cannot be obtained unless such hydrophilic fine particles are dispersed in water as solid fine particles, and the amount of the fine particles is about 5% to about 50% by weight, more preferably about 5% by weight based on the total weight of the emulsion. It is used in a range of 10% to 30% by weight.

Preferably, the aqueous phase further contains one or more of a hydrophilic polymer compound, a wetting agent, a water-soluble salt, and an acid.

Hydrophilic polymer compounds have the function of improving the hydrophilicity of non-image areas of planographic printing plates, and are also called water-soluble colloids. Any of them can be suitably used. Water-soluble cellulose ethers such as gum arabic, methylcellulose, ethylcellulose, carboxymethylcellulose, carboxyethylcellulose, oxyethylcellulose, dextrins, and polyacrylic acid, its water-soluble salts (such as sodium salts), polymethacrylic acid, its water-soluble Examples include water-soluble synthetic resins such as salts (for example, sodium salts), hydrolysates of copolymers of acrylic acid and vinyl acetate, and copolymers of acrylamide and acrylic acids, which may be used alone or Two or more can be used in combination. Among these, particularly preferred are gum arabic and dextrin. The amount of water-soluble polymer compound used is about 0.1% to about 25% by weight based on the total weight of the emulsion.
% by weight, more preferably in the range from 1 to 20% by weight.

The wetting agent can impart the property that the emulsion spreads appropriately over the plate surface of the lithographic printing plate. Preferred such wetting agents are polyhydric alcohols, with preferred specific examples being ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, tetraethylene glycol, polyethylene glycol, Examples include propylene glycol, tripropylene glycol, glycerin, sorbitol, pentaesthritol, and particularly preferred is glycerin. The wetting agent is approximately 0.1 to 0.1 to the total weight of the emulsion.
It can be used in an amount of about 1% by weight, more preferably in the range of 0.1 to 0.5% by weight.

The water-soluble salt has the function of making the non-image area more hydrophilic. Suitable water-soluble salts include alkali metal salts and ammonium salts, and those that give particularly good results include water-soluble salts of acids such as acetic acid, molybdic acid, boric acid, nitric acid, sulfuric acid, silicic acid, phosphoric acid and polyphosphoric acid. Includes alkali metal salts and ammonium salts. Specifically, ammonium acetate,
Sodium acetate, potassium acetate, sodium molybdate, potassium molybdate, sodium borate, ammonium borate, lithium nitrate, sodium nitrate, potassium nitrate, sodium silicate, dibasic sodium phosphate, tribasic sodium phosphate, dibasic potassium phosphate, tribasic potassium phosphate , triammonium phosphate, sodium polyphosphate, and the like. Among the above, particularly preferred are potassium acetate, sodium borate, ammonium borate, potassium borate,
These are sodium molybdate, potassium molybdate, and potassium sulfate. Such water-soluble salts can be used alone or in combination of two or more,
It is used in an amount of about 0.01 to about 1% by weight, more preferably 0.01 to 0.1% by weight, based on the total weight of the emulsion.

The acid is used primarily to adjust the pH of the emulsion. Inorganic acids such as phosphoric acid, pyrophosphoric acid, polyphosphoric acid, monosodium phosphate, boric acid, hydrochloric acid, sulfuric acid, nitric acid, such as succinic acid,
Organic acids such as oxalic acid, citric acid, maleic acid, lactic acid, p-toluenesulfonic acid, and benzenesulfonic acid can be used, and these are used alone or in combination of two or more. Among these, phosphoric acid and succinic acid are particularly preferred since they have the effect of desensitizing the non-image areas of the lithographic printing plate. On the other hand, the lipophilic substance constituting the oil phase of the emulsion consists of a water-insoluble organic solvent that itself exhibits lipophilic properties and a water-insoluble organic solvent that dissolves and contains the lipophilic substance (this organic solvent is itself lipophilic). (including both other items).

Preferred specific examples of the former solvent include dibutyl phthalate, diheptyl phthalate, di-n-
Octyl phthalate, di(2-ethylhexyl)
Phthalate diesters such as phthalate, dinonyl phthalate, didecyl phthalate, dilauryl phthalate, butylbenzyl phthalate, such as dioctyl adipate, butyl glycol adipate, dioctyl azelate, dibutyl sebacate, di(2-ethylhexyl) sebacate, dioctyl sebacate aliphatic dibasic acid esters such as cate, epoxidized triglycerides such as epoxidized soybean oil, phosphoric acid esters such as tricresyl phosphate, trioctyl phosphate, trischlorethyl phosphate;
For example, plasticizers such as benzoic acid esters such as benzyl benzoate have a freezing point of 15°C or lower and a boiling point of 300°C or higher at 1 atmosphere.

In addition to the above-mentioned plasticizers, the latter organic solvents include, for example, turpentine oil, xylene, toluene, n-heptane, solvent naphtha, kerosene, mineral spirits, and petroleum distillates with a boiling point of about 120°C to about 250°C. Contains hydrocarbons.

In any case, in addition to the above-mentioned solvents, for example, ketones such as cyclohexanone, halogenated hydrocarbons such as ethylene dichloride, such as ethylene glycol monomethyl ether, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether, etc. Ethylene glycol ethers and the like can be used in combination.

The water-insoluble organic solvent is used in an amount ranging from about 0.1 to about 10% by weight, more preferably from 0.5 to 5% by weight, based on the total weight of the emulsion.

Lipophilic substances include melamine resin, alkyd resin, polyester resin, epoxy resin, rosin,
Modified rosins such as hydrogenated rosin and rosin ester; petroleum resins such as gilsonite; oleic acid, lauric acid, valeric acid, nonyl acid,
These include organic carboxylic acids having 5 to 25 carbon atoms, such as capric acid, mystilic acid, palmitic acid, etc., and castor oil. Among these lipophilic substances, those that are liquid at room temperature, such as the above-mentioned organic carboxylic acids, can be used alone as an oil phase. These lipophilic substances can be used alone or in combination of two or more, and are based on the total weight of the emulsion.
It can be used in an amount of 1% by weight, more preferably in a range of 0.05 to 0.5% by weight.

The emulsion can contain a surfactant. This surfactant has the function of stabilizing the emulsion. Various kinds of surfactants can be used, such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. nonionic surfactants such as glycerin fatty acid esters, fatty acid salts, alkyl sulfate ester salts, alkylbenzenesulfonate salts, alkylnaphthalene sulfonate salts, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, anionic surfactants such as polyoxyethylene alkyl sulfate salts, cationic surfactants such as alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and betaine interfaces such as alkylbetaines. Examples include amphoteric surfactants typified by surfactants. Surfactants can be used in amounts ranging from about 0.001 to about 0.1% by weight, more preferably from 0.005 to 0.015% by weight, based on the total weight of the emulsion.

When carrying out the present invention using the emulsion as described above, it is convenient to pour an appropriate amount of the emulsion onto the surface of a lithographic printing plate and spread it over the entire surface using a sponge or the like. be. As a result, the lipophilic substance constituting the oil phase of the emulsion adheres to the image area of the lithographic printing plate, protecting the image area, while the concave portions of the roughened surface of the non-image area are filled with the aqueous phase of the emulsion. is filled with hydrophilic fine particles dispersed within. Therefore, there is no decrease in the oil sensitivity of the image area due to the adhesion of hydrophilic fine particles to the image area.

According to the present invention, a lithographic printing plate that is naturally prone to staining can be made into a lithographic printing plate that is resistant to staining very effectively and easily. In addition, it compensates for the drawbacks that the support and image forming materials have against printing stains, and even if they are excellent in terms other than stains (e.g., image adhesion, abrasion resistance of the image area), their use is limited due to the generation of stains. Many of the previously used printing materials can now be used more widely.

Hereinafter, the present invention will be explained in more detail based on examples. Note that % indicates weight %.

Example 1 A 0.24 mm thick 2S aluminum sheet was degreased by immersing it in a 5% aqueous solution of tribasic sodium phosphate at 70° C. for 1 minute. Next, graining was carried out in an approximately 1% hydrochloric acid solution by applying an alternating current of 10 volts at room temperature for approximately 20 minutes. Furthermore, in approximately 20% sulfuric acid aqueous solution
Anodic oxidation was carried out for 5 minutes at a current density of 1 Amp/dm ² . The amount of aluminum oxide film was approximately 3 g/m ² . It was then immersed in a 10% orthophosphoric acid solution at 55° C. for 23 seconds to perform etching of approximately 0.8 g/m ² .
A 0.2 g/m ² gelatin subbing layer was provided on this support. Furthermore, a 3 g/m ² photosensitive layer having the following composition was provided.

The photosensitive layer contains 10 g of 4-phenylcatechol (developing agent) in a gelatin silver chlorobromide emulsion (containing 30 g of silver chlorobromide consisting of 30 mol% silver chloride and 43 g of gelatin. Ortho-sensitized). , tricresyl phosphate 10g, vinyl chloride-vinyl acetate (84:
16 mol%) copolymer and 0.8 g of sodium nonylbenzenesulfonate (dispersant) were added and emulsified and dispersed in 30 g of ethyl acetate, and polyethyl methacrylate fine particles (average particle size An emulsion containing 20g of 0.2μ) was added and mixed uniformly.

On the photosensitive layer, a repeating unit -(O・CO−CH=
CH−C ₆ H ₄ −CH=CH−CO・O−CH ₂ −CH ₂ −
C ₆ H ₁₀ -CH ₂ -CH ₂ -) _o About 0.2 g/m ² protective layers were provided.

The photosensitive lithographic printing plate thus prepared was exposed for 3 seconds using a tungsten light source by projecting a character original taken on a microfilm with a reduction amount of 1/5 and enlarging it five times. The light intensity in the highlight part was 120 cms. After developing for 45 seconds at 32℃ using a developer with the following composition,
A relief image was obtained by washing out for seconds.

Composition of developer Anhydrous sodium carbonate 112.5g Potassium bromide 1.5g Calgon (sodium polymetaphosphate manufactured by Calgon Inc., USA) 1g Add water to 1000ml (PH11.7) The lithographic printing plate thus obtained was divided into two parts, one of which was normal The lattice was filled and gummed using the method described in the following. On the other hand, another lithographic printing plate was immersed in a fine particle dispersion having the following composition at 40°C for 1 minute, washed with water, and then lacquered and gummed in the same manner as above.

Composition of fine particle dispersion Snotex O (manufactured by Nissan Chemical Co., Ltd., particle size 10~
Milky white aqueous solution with pH 3.0 to 4.0 containing 20 to 21% of SiO ₂ (20 mμ) 1 part by weight deionized water 4 parts by weight When printing was performed using these lithographic printing plates, treatment with the fine particle dispersion was performed. The plate that was not treated produced prints with stains in the non-image areas from the beginning, but the lithographic printing plate that underwent the above treatment gave prints without stains, and this effect persisted even after 300 million prints.

Example 2 In the same manner as in Example 1, except that instead of dipping in the fine particle dispersion, the surface of the lithographic printing plate was soaked several times with a sponge soaked in this liquid (25°C). It was treated by rubbing it in a similar manner. The lithographic printing plate treated in this manner gave over 500,000 smudge-free prints as in Example 1.

Example 3 A lithographic printing plate was made in the same manner as in Example 1, except that a fine particle dispersion having the following composition was used.

3% sodium diphosphate aqueous solution 3 parts by weight Snowtex 20 (manufactured by Nissan Chemical Co., Ltd., particle size 10-20
Milky white aqueous solution with pH _9.5-10 containing 20-21% SiO2 of mμ) 1 part by weight This lithographic printing plate gave a large number of excellent prints with no stains in the non-image areas.

Example 4 An aluminum plate with a thickness of 0.24 mm was immersed in a 7% aqueous solution of tertiary sodium phosphate at 60°C to degrease it, washed with water, and then rubbed with a nylon brush while running a solution of pumice suspended in water for graining. did. JIS No. 3 sodium silicate (SO ₂ /Na ₂ O) kept at 70℃ after washing with water.
(molar ratio) = 3.1 to 3.3) for 30 to 60 seconds.

After thoroughly washing with water and drying, the next photosensitive solution was applied.

2-Hydroxyethyl methacrylate copolymer (as described in Example 1 of GB 1505739) 0.87 g 2-methoxy-4-hydroxy-benzoyl condensate of p-diazodiphenylamine and paraformaldehyde Benzene sulfonate 0.1 g Oil Blue #603 (manufactured by Orient Chemical Industry Co., Ltd.) 0.03 g 2-methoxyethanol 6 g Methanol 6 g Ethylene dichloride 6 g The coating was applied so that the weight after drying was 1.0 g/m ² . This photosensitive lithographic printing plate was allowed to age for two years under natural conditions to be affected by temperature and humidity. This aged plate was image-exposed for 40 seconds from a distance of 1 m using a metal halide lamp, and after being immersed in the following developer for 1 minute at room temperature, the surface was lightly rubbed with absorbent cotton to remove the unexposed areas and the lithographic printing plate I got it.

Benzyl alcohol 3.0g Sodium isopropylnaphthalene sulfonate
1.0g Sodium silicate (40% aqueous solution) 1.0g Water 95.0g This lithographic printing plate was divided into two parts, and one part was gummed with an ordinary gum arabic aqueous solution.
When printing was carried out using the normal procedure, slight stains were observed in the non-image areas of the printed matter.

The other lithographic printing plate was coated with an emulsion having the following composition in a sponge, and then subjected to gumming and subsequent treatments in the same manner as in the above case.

3 parts by weight of water containing oleic acid dispersed with a nonionic surfactant to a concentration of 5% Snowtex 20 1 part by weight The lithographic printing plate thus treated gave more than 500,000 copies of good quality prints with no stains in the non-image areas.
Further, no decrease in oil sensitivity of the image area due to treatment with the above emulsion was observed.

Example 5 A lithographic printing plate was prepared in the same manner as in Example 1, except that the emulsion treatment in Example 4 was applied instead of the fine particle dispersion treatment. This lithographic printing plate had higher oil sensitivity in the image area than in Example 1, and also gave a good quality printed matter with no stains in the non-image area.

Example 6 In the same manner as in Example 1, except that ultrafine titanium oxide (Nippon Aerosil Sales, West Germany DEGUSSA, particle size 2 to 5) was used as the fine particle dispersion.
When a lithographic printing plate was made using a solution in which 5g/100g water was dispersed using ultrasonic waves, good printed matter without stains was obtained. In this liquid
When 3% of JIS No. 3 sodium silicate aqueous solution was added, the stain prevention effect was further enhanced.

Example 7 In the same manner as in Example 1, however, caustic soda was added to a 20% aqueous calcium chloride solution as a fine particle dispersion in an amount that did not cause precipitation of calcium hydroxide.
Furthermore, a solution was prepared in which 5% of ultrafine calcium carbonate was added, and the lithographic printing plate was immersed at 40°C for 1 minute. Although the stain prevention effect is observed even when fine powder is not added,
More than 50,000 prints without stains were obtained by adding fine powder. However, in this case, since no lipophilic substance was added, poor inking occurred in the image area, but no problem occurred in printing by applying a developing ink composition having the following composition.

developing ink composition An emulsion of the solvent phase and aqueous phase described below.

Solvent phase Parts by weight Turpentine 7.0 Toluene 8.0 Sorbitan monostearate (Span-60, manufactured by Kao Atlas Co., Ltd.) 2.0 Sorbitan tristearate (Span-65, manufactured by Kao Atlas Co., Ltd.) 0.3 Petroleum resin (Petrozine #120, Mitsui Petrochemical Co., Ltd.
1.5 Rosin 0.5 Asphalt powder 1.0 Carbon black 2.2 Aqueous phase Water by weight 60.0 Glycerin 5.0 Gum arabic 10.0 Phosphoric acid (85% by weight) 2.0 Sodium borate 0.5

Claims (1)

[Scope of Claims] 1. A photosensitive lithographic printing plate having a photosensitive layer on the roughened surface of a metal support having a hydrophilic roughened surface is imagewise exposed and developed to produce the image of the photosensitive layer. After removing either the exposed portion or the unexposed portion during exposure to expose the roughened surface,
A method for making a lithographic printing plate, which comprises filling the exposed roughened surface with at least one hydrophilic fine particle selected from calcium hydroxide, calcium carbonate, aluminum oxide, titanium oxide, and silicon oxide. 2 A photosensitive lithographic printing plate having a photosensitive layer on the roughened surface of a metal support having a hydrophilic roughened surface is imagewise exposed and developed to reveal the exposed portions of the photosensitive layer in the imagewise exposure and the unexposed portions of the photosensitive layer. After removing one of the exposed parts and exposing it to the roughened surface,
In a method for making a lithographic printing plate in which the exposed roughened surface is filled with at least one hydrophilic fine particle selected from calcium hydroxide, calcium carbonate, aluminum oxide, titanium oxide and silicon oxide, the hydrophilic fine particles are A method characterized in that filling is carried out by applying an emulsion of an aqueous phase containing suspended hydrophilic fine particles and an oil phase consisting of a lipophilic substance to the exposed roughened surface.