JP2000221696A - Plate surface cleaner for planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an emulsion type plate surface cleaner for a planographic printing plate having superior contaminant removing capability to various contamination phenomena, capable of persistently exhibiting desensitization action and having high environmental safety and good work efficiency by incorporating a specified compound into an oil phase. SOLUTION: The emulsion type plate surface cleaner contains at least one aliphatic carboxylic ester compound of the formula H3C-(CH2)n-COOR1 or H3C- CH(OH)-COOR2 in the oil phase. In the formulae, each of R1 and R2 is an 8-18C aliphatic hydrocarbon group, this group may be any of saturated and unsaturated groups and any of linear and branched groups and (n) is 0, 1 or 2. The aliphatic carboxylic ester compound is, e.g. an ester of acetic acid, propionic acid, butyric acid or lactic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate cleaning agent for a lithographic printing plate, and more particularly, to a plate cleaning agent having both an ability to remove stains from various stains in a non-image area of the lithographic printing plate and a desensitizing effect.

[0002]

2. Description of the Related Art Lithographic printing is a printing method that skillfully utilizes the property that water and oil are not essentially mixed. The printing plate surface receives water and repels oily ink with a region that repels water. It consists of an area that accepts oil-based ink, the former being the non-image area and the latter being the image area. Therefore, when the balance is lost, for example, if the hydrophilicity of the non-image area deteriorates for some reason, ink often adheres to the area, resulting in so-called "ground stain". There are various cases where such background soiling occurs, but typical examples include cases where the lithographic printing plate has been subjected to a treatment such as burning applied to make the lithographic printing plate have high printing durability, or a lithographic printing plate. In some cases, the plate surface was left in the air without being protected by the desensitizing gum. Such a decrease may also occur when the printing press is stopped due to a trouble in the printing press or a break during printing. Therefore, when the printing press is stopped, usually, printing personnel have a habit of applying a desensitized gum solution. Further, when a lipophilic substance adheres to the non-image area of the lithographic printing plate to which the desensitizing gum is not applied and is left as it is, the part becomes sensitized and becomes soiled. For example, a trace of a fingerprint or the like appears on the background of a printed matter due to a similar cause. Furthermore, it is a case where the non-image area is scratched, and in this case, the ink is clogged in the scratch,
It is gradually sensitized and becomes dirty.

A lithographic printing plate having a stain as described above removes ink on the plate surface and restores the hydrophilicity of a non-image area by a so-called plate surface cleaning agent (sometimes called a plate cleaner). What is processed in is usually. As one of such plate surface cleaning agents, a cleaning agent composed of a calculated sodium aqueous solution has been known. However, although this plate surface cleaning agent has an effect of extremely high desensitizing effect, it is alkali-sensitive and is therefore a photosensitive lithographic printing plate developed with an aqueous alkali developing solution.
No. 3-28403, U.S. Pat. No. 3,046,120, etc., a positive-working photosensitive lithographic printing plate having a photosensitive layer comprising an o-quinonediazide compound or JP-A-54-98613, a British patent. When used in a lithographic printing plate prepared from a negative-working photosensitive lithographic printing plate having a photosensitive layer composed of a binder having an acidic group and a diazo resin as described in JP-A No. 1,350,521, a part of an image area is used. And the adhesion of the ink is degraded. On the other hand, the plate cleaner using oxalic acid described in U.S. Pat. No. 3,489,561 has a weak desensitizing power and a strong effect of corroding a metal support. Therefore, an aluminum plate is used as a support. A hydrophilic layer (for example, as described in U.S. Pat. No. 2,714,066) applied to the surface of a support of an ordinary photosensitive lithographic printing plate (referred to as PS plate). The metal support is not suitable because the layer formed by the treatment is destroyed and soiling is likely to occur.

In general, when stains occur during printing, the ink on the plate surface is first removed with a cleaning agent (kerosene or hydrocarbon solvent) and then treated with a desensitizing agent. Since the conventional plate surface cleaning agent as described above also needs to be applied after the plate surface has been washed with an ink cleaning agent, the plate surface cleaning agent treatment is complicated, requiring two processing steps. Therefore, in recent years, emulsified plate surface cleaners having both functions integrated, that is, having both an ink cleaning agent function and a desensitizing effect, have been developed. For example, Japanese Patent Application Laid-Open No. 52-15702 discloses an alkaline emulsified plate surface cleaner.
No. 02 discloses an acidic emulsified plate surface cleaner.
On the other hand, in the oil phase of the emulsified plate cleaning agent, a hydrocarbon-based solvent generally containing a large amount of aromatic hydrocarbons has a function of eluting and removing ink adhering to the lithographic printing plate. It is used. In recent years, this aromatic hydrocarbon-based solvent is said to be a compound that has an adverse effect on the human body, and has a serious problem. Accordingly, aliphatic hydrocarbons and the like have been proposed as alternative solvents for the aromatic hydrocarbons. However, these aliphatic hydrocarbons have problems such as insufficient cleanability of special inks such as UV inks and metal inks.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to have a dirt removing ability excellent in various types of dirt phenomena, and to be able to fully demonstrate the desensitizing effect, and to provide a high environmental safety and high workability. An object of the present invention is to provide a plate cleaning agent for a lithographic printing plate having good properties.

[0006]

As a result of various studies, the present inventors have achieved the above objects by emulsifying a specific compound in the oil phase of an emulsion type lithographic printing plate cleaning agent. They have found that this can be achieved and have completed the present invention. Accordingly, the present invention is an emulsion type lithographic printing plate cleaning agent, characterized in that the oil phase contains at least one compound represented by the following general formula [I] or [II]. The present invention relates to a plate cleaning agent for lithographic printing plates. H ₃ C— (CH ₂ ) _n —COOR ¹ [I] H ₃ C—CH (OH) —COOR ² [II] (wherein, R ¹ and R ² each represent an aliphatic carbon having 8 to 18 carbon atoms. Represents a hydrogen group, and n represents 0 or an integer of 1 to 2.)

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The aliphatic carboxylic acid ester compound represented by the general formula [I] or [II] used in the plate cleaning agent for a lithographic printing plate of the present invention is specifically an ester of acetic acid, propionic acid, butyric acid or lactic acid. . In the formula, the aliphatic hydrocarbon group having 8 to 18 carbon atoms represented by R ¹ and R ² may be specifically unsaturated or saturated, and may be linear or branched. When the number of carbon atoms of the aliphatic hydrocarbon group is less than 8, the ink elution property is excellent, but there is a problem that the printing durability of the photosensitive layer of the printing plate tends to deteriorate. On the other hand, if the number of carbon atoms is 1
If it exceeds 8, the dissolution of the ink tends to deteriorate, which is not preferable.

Preferred carboxylic acid ester compounds for use in the present invention include octyl such as acetic acid, butyric acid and lactic acid, 2-ethylhexyl, capryl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, and the like.
Examples include esters of pentadecyl, cetyl, and oleyl. Particularly preferred are octyl lactate, 2-ethylhexyl lactate, caprylic lactate, nonyl lactate, decyl lactate, lauryl lactate, cetyl lactate, 2-ethylhexyl butyrate, cetyl butyrate, and the like. Among these, lactic acid ester compounds exhibit particularly excellent effects of dissolution on various inks, and on the other hand, have little effect on the photosensitive layer of the printing plate, and thus can be preferably used. . These aliphatic carboxylic acid ester compounds can be used alone or in combination of two or more.

The content of the carboxylic acid ester compound in the emulsion type lithographic printing plate cleaning agent of the present invention is 0.5 to 15 based on the total weight of the plate cleaning agent in consideration of economy.
% Is suitable, preferably in the range of 1 to 10% by weight. The emulsifying type plate cleaning agent of the present invention is classified into an acidic plate cleaning agent having a pH of 1 to 4 and an alkaline plate cleaning agent having a pH of 10 to 13, and both can be preferably used.

The acidic emulsification type plate surface cleaner of the present invention comprises (1)
A water-soluble polymer compound, (2) phosphoric acid, polymerized phosphoric acid, an alkali metal salt thereof, at least one compound selected from the group consisting of organic phosphonic acids and salts thereof, (3) nitrate,
(4) a water phase containing a sulfate or bisulfate, (5) water, and an oil phase containing the above-mentioned aliphatic carboxylic acid ester and further having a dissolving action on ink (6) an oil phase which may contain a hydrocarbon solvent. Become. The composition further comprises (7) a surfactant, (8) a wetting agent, (9) a thixotropic agent,
0) A pH adjuster can be contained as needed. In the plate surface cleaning agent of the present invention, in addition to the above components, a preservative,
A bactericide, a coloring agent and the like may be added.

Specific examples of the water-soluble polymer compound of the component (1) include dextrin, cyclodextrin,
Alginates, cellulose derivatives (for example, carboxymethylcellulose, carboxyethylcellulose, hydroxyethylcellulose, methylcellulose, etc.), gum arabic, natural products such as soybean polysaccharides and modified products thereof, and polyvinyl alcohol and derivatives thereof, polyvinylpyrrolidone,
Polyacrylamide and its copolymer, acrylic acid copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene /
Synthetic products such as a maleic anhydride copolymer are exemplified. These substances can be used alone or as a mixture. In order to make the plate surface cleaner have a preferable viscosity range (about 200 cps to 2,000 cps), the amount of the material used is 1 to 24% by weight based on the total weight of the plate surface cleaner. Suitable, more preferably 3
It can be selected from the range of ２０20% by weight.

The above component (2) includes, for example, phosphoric acid, sodium phosphate, potassium phosphate, lithium phosphate, pyrophosphate, sodium pyrophosphate, potassium pyrophosphate, lithium pyrophosphate, tripolyphosphate, sodium tripolyphosphate, tripolyphosphate Potassium, lithium tripolyphosphate, tetraphosphate, sodium tetraphosphate, potassium tetraphosphate, lithium tetraphosphate, hexametaphosphate, sodium hexametaphosphate, potassium hexametaphosphate, lithium hexametaphosphate, methylene diphosphonic acid, 1-hydroxyethane 1,1-disulfone Acid, nitrilotrisphosphonic acid, N-carboxymethyl N, N-di (methylenephosphonic acid), hexamethylenediamine-tetra (methylenephosphonic acid), ethylenediamine-tetra (methylenephosphonic acid), diethylene Riamin - penta (methylene phosphonic acid), N, N-di (carboxymethyl) -N- methylene phosphonic acid, N- (2- hydroxyethyl) -
N, N-di (methylenephosphonic acid), N-hydroxymethyl-N, N'N'-ethylenediaminetris (methylenephosphonic acid), N-hydroxyethyl-N ', N'-
Diethylethylenediamine-N, N, N ', N'-tetra (methylenephosphonic acid), di (2-hydroxypropylene) triaminepenta (methylenephosphonic acid), tri (2-hydroxypropylene) tetraaminehexa (methylenephosphonic acid) And the like. These compounds are commercially available, for example from Monsanto Chemical Company as "DEQUESTs" and also from Philip A Hant Chemical Corporation.
ical Corp)
ical Division) as "WAYPLEX". The compounds as described above can be used alone or in combination of two or more kinds.
It is contained so as to be in the range of 0.5 to 10% by weight.

The nitrate of the component (3) used in the present invention includes zinc nitrate, cobalt nitrate, magnesium nitrate,
Sodium nitrate, potassium nitrate, nickel nitrate, bismuth nitrate, tin nitrate, strontium nitrate, cesium nitrate,
Metal salts of nitric acid such as cerium nitrate and ammonium nitrate. The use range of the water-soluble metal nitrate used in the present invention is 0.5 to 10% by weight, more preferably 1 to 5% by weight based on the total weight of the composition.

The sulfate or bisulfate of the component (4) used in the present invention includes, for example, sodium sulfate, potassium sulfate, aluminum sulfate and the like. The bisulfate is represented by the general formula M (HSO ₄ ) _n (where M represents a metal and n represents the valence of M), for example, strontium hydrogen sulfate, potassium hydrogen sulfate, calcium hydrogen sulfate, sulfuric acid Examples thereof include thallium hydrogen, sodium hydrogen sulfate, lead hydrogen sulfate, bismuth hydrogen sulfate, magnesium hydrogen sulfate, and rhodium hydrogen sulfate. These compounds can be used alone or in combination of two or more, and contained in an amount of 0.01 to 5% by weight, more preferably 0.1 to 3% by weight, based on the total weight of the plate cleaning agent according to the present invention. Can be The remaining component of the aqueous phase of the plate cleaning agent of the present invention is water, the amount of which is 45 to 85 based on the total weight of the plate cleaning agent of the present invention.
% Is suitable, more preferably 50-80% by weight
It is.

On the other hand, in the oil phase of the plate surface cleaning agent of the present invention, the hydrocarbon solvent of the component (6) can be used in combination. As the component (6), a petroleum fraction having a boiling point of 120 to 350 ° C., which is usually used for washing printing ink, is particularly useful. As a specific example of such a hydrocarbon solvent, for example, a product of Nippon Petrochemical Co., Ltd., having a boiling point of 150 to 20
0 ° C cleansol, dry solvent, A solvent,
K Solvent, Mineral Spirit A and Hyalom 2
5, insecticide solvent, fog solvent and non-sulfur solvent having a boiling point of 200 to 250 ° C, boiling point 250
No. 3 solvent, No. 4 solvent, No. 5 solvent, No. 6 solvent and No. 7 solvent at -300 ° C. The range of use of this hydrocarbon solvent is 5% of the total composition weight.
-40% by weight, more preferably 10-30% by weight. The component (6) is not mixed with the water of the component (5), so that it is used in a state of being sufficiently mixed and dispersed when used. At this time, it is useful to add a surfactant of component (7) for the purpose of enhancing the stability of dispersion. Surfactants that can be used in the present invention include anionic surfactants and nonionic surfactants.

Examples of the anionic surfactant include fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkanesulfonates, dialkylsulfosuccinates, straight-chain alkylbenzenesulfonates, branched-chain alkylbenzenesulfonates, and alkylnaphthalenes. Sulfonates, alkylphenoxypolyoxyethylene propylsulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyltaurine sodium salts, N-alkylsulfosuccinic acid monoamide disodium salts, petroleum sulfonates, sulfuric acid Castor oil, sulfated tallow oil, fatty acid alkyl ester sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monog Celide sulfates, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene -Partially saponified maleic anhydride copolymers, partially saponified olefin-maleic anhydride copolymers, and formalin condensates of naphthalenesulfonic acid salts. Among them, dialkyl sulfosuccinates, alkyl sulfates and alkylbenzene sulfonates are particularly preferably used.

Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, and glycerin fatty acid moieties. Esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol Fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid Ethers, fatty acid diethanolamides, N, N-bis-2-hydroxyalkylamines,
Examples thereof include polyoxyethylene alkylamines, triethanolamine fatty acid esters, and trialkylamine oxides. Among them, polyoxyethylene alkyl phenyl ethers, polyoxyethylene-polyoxypropylene block polymers and the like are preferably used. Two or more of these surfactants may be used in combination. The amount used is not particularly limited, but the preferred range is 0.5 to 10% by weight of the total composition weight.

In addition to the above components, one or more wetting agents (component (8)) which impart good spreading properties to the plate surface cleaning agent, suppress drying, and improve useability are also useful. Suitable wetting agents have the general _{formula: HO- (R-O) n} -H ( wherein R is _{C m H 2m (m = 2~6} ), n is a is 1 to 500) is represented by compounds It is. Specific examples of preferred compounds include ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and the like. Glycerin, sorbitol and pentaerythritol are useful as humectants. The amount of the wetting agent used is in the range of 5 to 30% by weight of the total composition weight, and the effect is more preferably in the range of 10 to 25% by weight.

The thixotropic agent of the component (9) lowers the viscosity of the liquid due to dynamic pressure and increases the viscosity when the liquid is still, thereby improving the working characteristics when treating the plate surface with a sponge or the like. Suitable thixotropic agents include finely divided silica,
Pumice, calcium carbonate, zeolite and the like.
The amount used is suitably in the range of 0.5 to 10% by weight of the total composition weight, and preferably in the range of 1 to 7% by weight. As mentioned above, the plate surface cleaning agent of the present invention has a pH of 1 to 4
Is adjusted to the range. The pH adjusting agent (component (10)) used for adjusting the pH to such a pH range includes sulfuric acid, phosphorous acid, citric acid, acetic acid, oxalic acid, malonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, and the like. Butyric acid, maleic acid,
An acid such as picolinic acid is used, and an alkali such as sodium hydroxide, potassium hydroxide or lithium hydroxide may be used in combination.

In addition to the above components, preservatives (bactericides), coloring agents and the like can be added. As a preservative, phenol or a derivative thereof, formalin, imidazole derivative, sodium dihydroacetate, 4-isothiazolin-3-one derivative, benzisothiazolin-3-one derivative, benztriazole derivative, amidizing anidine derivative, quaternary ammonium salt pyridine, quinoline Derivatives such as guanidine, diazines, triazole derivatives, oxazoles, oxazine derivatives, and bromonitro alcohols such as 2-bromo-2-nitropropane-1,3-diol are exemplified. Preferred amounts of the preservative are bacteria,
It is an amount stably exerted on mold, yeast and the like, and is generally 0.01 to 3 based on the total weight of the plate cleaning agent.
It is preferably added in the vicinity of weight%, and two or more preservatives are preferably used in combination so as to be effective against various molds and bacteria.

The colorant is used for imparting a desired color tone to the plate surface cleaning agent of the present invention to give a visual contrast, and can be selected from a wide range of dyes. As a particularly preferred coloring agent, a color tone such as blue, purple, or red is suitably used. Specific examples include crystal violet, safranin, brilliant blue, malachite green, and acid rhodamine B. The amount used is 0.000 with respect to the total weight of the plate cleaning agent of the present invention.
1 to 0.1% by weight is suitable, more preferably 0.000%.
It is in the range of 3 to 0.05% by weight.

When the plate cleaning agent of the present invention is used as an alkaline plate cleaning agent, (1) a water-soluble polymer compound, (11)
General formula M ₂ O.nSiO ₂ [M is an alkali metal, -N (C
_{H 3) 4, -N (CH} 2 CH 3) 4, -N (CH 2 OH) 4 or -N
(C ₂ H ₄ OH) ₄ , n is an aqueous solution or colloidal solution of a silicate represented by 1 to 3.2], (5) an aqueous phase containing water, the above-mentioned aliphatic carboxylic acid ester, and further an ink. It consists of an oil phase which may contain a hydrocarbon solvent having a dissolving action (6). The composition further comprises at least a component (7) a surfactant, (8) a wetting agent, (12) molybdic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid and water-soluble salts thereof. One kind, (10) pH adjuster can be contained as needed.

As the silicate of the component (11), sodium silicate, lithium silicate, potassium silicate, rubidium silicate, cesium silicate, tetramethylammonium silicate, tetraethylammonium silicate,
Examples include tetramethanol ammonium silicate and tetraethanol ammonium silicate. or,
Colloidal silica, available from DuPont under the trade name LuDox, can be used as the colloid solution as well. The use range of the silicate used in the present invention is 1 to 30% by weight, more preferably 2 to 20% by weight of the total composition weight. Optional component (6) in alkaline stencil cleaner
The range of use of the hydrocarbon solvent is 10 to 5 parts by weight of the total composition.
0% by weight, more preferably 15 to 40% by weight. Since the water phase and the oil phase do not mix, when used, they are used in a state of being sufficiently mixed and dispersed. It is useful to add a surfactant of component (7) for the purpose of enhancing the stability of dispersion. The types and amounts of the components (1), (7) and (8) are the same as those of the acidic plate cleaning agent.

The function of the plate surface cleaning agent is to prevent background contamination caused by scratches generated in the hydrophilic layer and to maintain and strengthen the recovered hydrophilicity. This action is achieved by using at least one selected from molybdic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid and water-soluble salts thereof, preferably alkali metal salts and ammonium salts, as the component (12). Enhanced by For example, sodium molybdate, potassium molybdate, lithium molybdate, ammonium molybdate, sodium borate, potassium borate, lithium borate, ammonium borate, sodium nitrate, potassium nitrate, potassium nitrate, lithium nitrate, sodium phosphate, potassium phosphate, phosphorus Examples thereof include lithium acid, ammonium phosphate, sodium pyrophosphate, potassium pyrophosphate, lithium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, lithium tripolyphosphate, sodium hexametaphosphate, potassium hexametaphosphate, and lithium hexametaphosphate. The compounds are used in the range from 0.1 to 10% by weight of the total composition weight, more preferably in the range from 0.2 to 5% by weight.

The component (11) represented by the general formula M ₂ O.nSiO ₂ maximizes the ability of the plate surface cleaning agent to remove stains in the pH range of 10 to 13. To adjust to this pH range,
PH adjusters such as sodium hydroxide and potassium hydroxide (1
0) is used. In the alkaline plate cleaning agent, besides the above components, pumice, silica powder, granular powder such as zeolite,
Preservatives, bactericides, coloring agents and the like may be added. The alkaline stencil cleaner exhibits particularly excellent performance when the pH value of the aqueous phase is in the range of 11 to 14, more preferably 11.5 to 13. Therefore, to adjust the pH to such a pH range,
For example, phosphoric acid, sodium hydroxide, potassium hydroxide and the like are added as necessary.

The plate surface detergent for a lithographic printing plate of the present invention can be produced as a general emulsified O / W type or W / O type emulsion according to a conventional method. In order to use the lithographic printing plate cleaning agent of the present invention, the cleaning agent may be contained in a cloth, sponge, or the like, wiped off a stained portion, left for about 30 seconds, and then wiped off with water.

[0027]

The plate surface cleaning agent of the present invention is for removing background stains attributable to a cause that has occurred at the time of plate making or during storage, printing, or any other stage from plate making to printing. For example, it has suitability only for a specific plate, and for some plates, it damages the image or deteriorates the inking property, or corrodes and destroys the hydrophilic layer of the non-image part. Overcoming the shortcomings of existing plate cleaning agents, such as poor ability to heal dirt due to scratches,
It is also useful for lithographic printing plates made from either negative or positive PS plates. Further features of the plate surface cleaning agent of the present invention include:
The effect of preventing background contamination caused by scratches or the like generated on the hydrophilic layer in the non-image portion of the lithographic printing plate and the effect of maintaining and enhancing the restored hydrophilicity are extremely strong. The plate surface cleaning agent of the present invention also uses a fatty acid ester compound as an ink-eluting component having high environmental safety. This makes it possible to better emulsify aliphatic hydrocarbons that have been difficult to emulsify in the past, and to improve odors compared to the use of aromatic hydrocarbon solvents, and is environmentally and physically safe. Can be enhanced. Further, since a relatively large amount of an oil component can be contained in the plate surface cleaning agent, the work time can be reduced.

[0028]

EXAMPLES Next, the emulsion type lithographic printing plate surface cleaner of the present invention will be described with reference to examples, but the present invention is not limited to these examples. "Parts" and "%" indicate parts by weight and% by weight, respectively, unless otherwise specified. Example 1 Gum Arabic (grade HP type) 8 in 563 g of pure water
0 g was dissolved with heating. Next, 30 g of sodium hexametaphosphate was dissolved with stirring, 20 g of magnesium nitrate and 5 g of sodium hydrogen sulfate were added in order, 15 g of phosphoric acid (85%), 50 g of glycerin as a wetting agent,
4-isothiazolin-3-one derivative 2.0 as preservative
g was mixed to prepare an aqueous phase. On the other hand, 2-ethylhexyl lactate (60 g), an aliphatic hydrocarbon solvent Exsol D-80
140 g (manufactured by Exxon Chemical Co., Ltd.), Perex OT-P (Kao Corporation dialkyl sulfonate) as an emulsifier
An oil phase was prepared by dissolving 20 g, 10 g of Neoperex F-60 (Kao Corporation dodecylbenzenesulfonate) and 5 g of Emulgen 105 (Kao Corporation polyoxyethylene lauryl ether).

Next, the aqueous phase prepared as described above was stirred and heated to adjust the temperature to 35 to 40 ° C., and the oil phase was slowly added dropwise to this aqueous phase to prepare a dispersion. The solution was adjusted to 1000 ml with pure water to prepare an emulsified plate surface cleaner. On the other hand, VPS-
II (Fuji Photo Film Co., Ltd. anodized multi-grain type positive PS plate) is image-exposed to a PS automatic processor 80
After developing with an aqueous solution of a positive developing solution DP-4 (diluted 8 times with water) using 0EII, the film was washed with water and dried. 4 printing plates
The plate was divided and processed under the conditions shown in Table 1, and a test was conducted for the ability to remove stains.

[0030]

[Table 1]

The plate created in this manner is referred to as Heidelberg S
On an OR-M type printing press, about 3
After processing for 0 seconds, the print was wiped off with water. After the start of printing, a normal printed matter having completely ink-coated was obtained on 7 to 10 sheets. Then, no stain was generated even after 30,000 sheets were printed. Observation of the halftone dots in the image portion on printing showed no difference in the size of the halftone dots and the degree of abrasion as compared with D which was not treated with the cleaning agent. In addition, as compared with the normal plate D which had not been subjected to the above-mentioned cleaning agent treatment, a normal printed matter was obtained for all of the ink stains and the like. Also,
After the treatment with the above-mentioned plate surface cleaning agent, almost no difference can be found in obtaining a normal printed matter from the start of printing between the case of wiping with water and the case of directly touching the water absorbing roll without wiping with water. Printed materials on which ink was completely deposited were obtained on 10 sheets.

Example 2 An aqueous phase and an oil phase having the following formulation (unit: gram (g)) were prepared in the same manner as in Example 1 to obtain a 1,000 ml emulsified plate surface cleaner. [Water phase] Pure water 593.0 Cellogen 6A (Daiichi Kogyo Chemical Co., Ltd. carboxymethylcellulose) 10.0 Water-soluble soybean polysaccharide (analytical value: galactose 43.6%, arabinose 22.5%, galacturonic acid 2. 50.0 Phosphoric acid 30.0 Potassium pyrophosphate 20.0 Ammonium nitrate 10.0 Glycerin 50.0 4-Isothiazolin-3-one derivative 2.0 (Adjusted to pH 2.0 with caustic soda) [Oil phase] Exol D-80 150.0 2-Ethylhexyl lactate 30.0 Lauryl lactate 20.0 Polyoxyethylene higher alcohol ether 10.0 (Emulgen 705 manufactured by Kao Corporation) Dialkyl sulfosuccinate 15.0 (Lapisol B-80) Sorbitan monooleate 10.0 (Nonion OP-80 manufactured by Nippon Yushi Co., Ltd.)

Example 3 An aqueous phase and an oil phase having the following formulation (unit: g) were prepared in the same manner as in Example 1 to obtain a total of 1,000 ml of an alkaline stencil cleaner. [Water phase] Pure water 565.0 Cellogen 6A (Daiichi Kogyo Chemical Co., Ltd. carboxymethyl cellulose) 60.0 No. 3 sodium silicate (40%) 30.0 Potassium pyrophosphate 10.0 Sodium hydroxide 5.0 Propylene Glycol 70.0 [Oil phase] Solvent K (Nippon Petrochemical Co., Ltd.) 150.0 2-Ethylhexyl lactate 50.0 Polyoxyethylene higher alcohol ether 25.0 (Emulgen 705 Kao Corporation) Dialkyl sulfosuccinic acid Sodium 15.0 (Lapisol B-80 manufactured by NOF Corporation) Pluronic P-85 20.0 (Polyoxyethylene / polyoxypropylene block polymer manufactured by Asahi Denka Co., Ltd.)

On the other hand, as a lithographic printing plate, FNS-A (a negative PS plate subjected to anodizing and hydrophilizing treatment, manufactured by Fuji Photo Film Co., Ltd.) was image-exposed, and a PS automatic developing machine 800EII was used.
Was developed with an aqueous solution of a negative developer DN-3C (diluted twice with water), washed with water, and dried. The printing plate was divided into four parts, the plate was processed under the conditions shown in Table 1, and a test was performed on the stain removal ability. On a Heidelberg SOR-M printing machine, the plate was treated with the above-mentioned plate surface cleaning agent for 30 seconds, wiped off with a sponge soaked in water, and then printed. The number of defective prints until a clear print was obtained was 10 to 20, and there was almost no difference as compared with the plate without treatment, which was a good result. In addition, no stain was generated even after 30,000 sheets were printed, and the dots of the image on the plate surface were observed. No difference was seen.

Examples 4 to 7 An aqueous phase and an oil phase were prepared according to the formulation (unit: gram (g)) shown in Table 2 below, and an acidic plate cleaning agent was prepared in the same manner as in Example 1.
(Examples 4 and 5, Comparative Example 1) were prepared and subjected to the same test. Further, an aqueous phase and an oil phase were prepared according to the formulation (unit: gram (g)) shown in Table 3, and an alkaline plate surface cleaning agent (Examples 6 and 7, Comparative Example 2) was prepared in the same manner as in Example 3. Prepared and subjected to similar tests. Table 4 shows the results.

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4] A Excellent △ Somewhat inferior × Inferior

As can be seen from the results in Table 4, all the surface cleaning agents for lithographic printing plates of the present invention exhibited satisfactory effects.

Claims (1)

[Claims] 1. A lithographic printing plate cleaning agent of an emulsion type, wherein the oil phase contains at least one compound represented by the following general formula [I] or [II]. Plate cleaning agent for printing plates. H ₃ C— (CH ₂ ) _n —COOR ¹ [I] H ₃ C—CH (OH) —COOR ² [II] (wherein, R ¹ and R ² each represent an aliphatic carbon having 8 to 18 carbon atoms. Represents a hydrogen group, and n represents 0 or an integer of 1 to 2.)