JPH0676572B2 - Development ink for planographic printing plates - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a developing ink for a lithographic printing plate,
Sometimes it relates to an emulsion type developing ink.

Lithographic printing is a printing method that skillfully utilizes the spirit that water and oil are essentially immiscible, and the printing plate surface receives water,
It consists of a region that repels oily ink and a region that repels water and receives oily ink. The former is called a non-image region and the latter is called an image region.

The developing ink for a lithographic printing plate is to make it easier to visually distinguish the image area and the non-image area of the lithographic printing plate, and at the same time to increase the receptivity of the printing ink by attaching a lipophilic substance to the image area, Further, it is applied to the lithographic printing plate in order to protect the image area in various operations such as gumming performed thereafter.

Needless to say, such a developing ink must have the above-mentioned various performances, but it is also necessary that it has the following performances.

(1) Even when the developing ink is applied to a halftone image formed on a lithographic printing plate, so-called kalami (that is, a lipophilic substance contained in the developing ink is present between adjacent halftone dots). The current state of adhesion, such as bridging in, or covering a small non-image area surrounded by the image area.)

(2) The colored image visualized with the developing ink faithfully reproduces the image area formed on the lithographic printing plate (for example, the visualized halftone dot is thicker than the actual halftone dot. No.).

(3) The developing ink itself has excellent stability over time (that is, the property immediately after production is maintained even after a long time has passed).

(4) When applying the developing ink to a lithographic printing plate, it can be done with a simple tool such as a sponge without using a special tool.

Conventionally known developing inks such as tinctor satisfy some of the above-mentioned performances,
No one was satisfied with all of these.

[Object of the Invention]

Therefore, an object of the present invention is to provide a developing ink that satisfies the above-mentioned various performances.

That is, it is an object of the present invention to provide a developing ink that does not cause coloration.

Another object of the present invention is to provide a developing ink that gives a visible image that faithfully reproduces the image area of a lithographic printing plate.

Another object of the present invention is to provide a developing ink having excellent stability over time.

Yet another object of the present invention is to provide a developing ink which can be applied onto a lithographic printing plate with a simple tool.

[Structure of Invention]

The present inventors have conducted various studies in order to achieve the above-mentioned objects, and as a result, a polybasic acid monoester derivative of a polysaccharide is used as a protective colloid substance for emulsion stabilization used in the aqueous phase of the developing ink for lithographic printing plates. The inventors have found that the above-mentioned object can be specifically achieved by using, and have completed the present invention.

That is, the present invention provides an emulsion type lithographic printing plate developing ink comprising an oil phase containing a colorant, an aqueous phase containing a water-soluble polymer compound, and a surfactant. Is at least one of the polybasic acid monoester derivatives of polysaccharides, which is a developing ink for a lithographic printing plate.

Hereinafter, the present invention will be described in detail.

(Polysaccharide) Polysaccharides that can be preferably used in the present invention are shown below.

As homoglycans (i) Glucan: cellulose, starch, glycogen, caronin, laminaran, dextran.

(Ii) Fructan: inulin, levan.

(Iii) Mannan: elephant palm mannan.

(Iv) Xylan: Xylan of rice straw.

(V) Galacturonan: pectic acid.

(Vi) Mannuronan: alginic acid.

(Vii) N-acetylglucosamine polymer: chitin.

As heteroglycans (i) diheteroglycan: guaran, konjac mannan, heparin, chondroitin sulfate, hyaluronic acid.

(Ii) Triheteroglycans: Meskit gum, Gatch gum, and many other plant mucilages, gums, bacterial polysaccharides.

(Iii) Tetraheteroglycan; gum arabic, mucilage of horse mackerel, many other mucilages, rubbery bacterial polysaccharides.

Although the above-mentioned polysaccharides include those which are not water-soluble as they are, they can be used in the present invention if they are made water-soluble by forming a polybasic acid monoester derivative.

From the viewpoint of economy, it is preferable to use a starch-based starch. As the starch, for example, starch obtained from potato, sweet potato, wheat, corn, rice, tapioca, corn (waxy corn), glutinous rice, etc. may be used. Particularly preferred are glutinous starches such as glutinous rice and waxy corn (waxy corn) having a high amylopectin content and fractionated amylopectin.

Amylopectin-type starch has the advantage that it has a property that the characteristic aging phenomenon of starch is unlikely to occur, and thus is advantageous in stability over time.

(Polybasic Acid) Polybasic acids that can be preferably used in the present invention are exemplified below.

Itaconic acid, maleic acid, phthalic acid, trimellitic acid,
Pyromellitic acid, endomethylenetetrahydrophthalic acid, chlorendic acid, methylendomethylenetetrahydrophthalic acid, tetrahydroxyphthalic acid, diphenic acid, citraconic acid, glutaconic acid, glutaric acid, succinic acid, hexaisobutenyl succinic acid, nonylsuccinic acid, n-octyl succinic acid, 2-ethyl-2-methyl succinic acid, dimethylbenzyl succinic acid, octenyl succinic acid, hexenyl succinic acid, decynyl glutaric acid, decenyl succinic acid and the like. Of these, particularly preferred are succinic acids such as octenyl succinic acid.

(Polybasic Acid Monoester Derivative of Polysaccharide) The polybasic acid monoester derivative of the polysaccharide used in the present invention can be advantageously obtained by esterifying the polysaccharide with an anhydride of the polybasic acid. it can.

Preferred examples of the polybasic acid monoester derivative of the polysaccharide used in the present invention include, for example, succinic acid monoesterified starch, octenyl succinic acid monoesterified starch, hexenyl succinic acid monoesterified starch, decynyl glutaric acid monoesterified starch, Examples thereof include odosenyl succinic acid monoesterified starch and maleic acid monoesterified starch. Of these, succinic acid monoesterified starches such as octenyl succinic acid monoesterified starch show particularly preferable effects.

The polybasic acid monoester derivative of the polysaccharide used in the present invention has one or more free carboxylic acid groups, but if necessary, an alkali metal salt such as sodium, potassium, lithium or an ammonium salt. Is also suitably used.

The preferred range of the viscosity of the polybasic acid monoester derivative of the polysaccharide used in the present invention is 50 cps or less in a 20% by weight aqueous solution (B type viscometer BL type, manufactured by Tokyo Keiki Co., Ltd., 20 ° C.),
It is more preferably 300 cps or less. In general, when the viscosity is 500 cps or more, it is difficult to apply the developing ink to the image area quickly by the hand-painting or the automatic developing-ink filling machine when the developing ink is deposited, and color unevenness easily occurs and the plate inspection work becomes difficult. A more preferable range of 300 cps or less is particularly effective for solving these problems. As a method of adjusting this viscosity,
Examples include heating roasting, enzyme modification, acid modification, and oxidation modification, and the necessary viscosity can be adjusted by the reaction conditions such as temperature, time and composition.

Generally, a polysaccharide derivative is one in which the chemical structure of a glucose unit in a polysaccharide molecule is changed (denaturation), and the degree of denaturation, that is, the degree of substitution (Degree of Svbstitution) is the inhibition of aging and gelation of the polysaccharide and retention of water. It is extremely important for improving the property, hydrophilicity or strengthening hydrophilicity. In the present specification, the degree of substitution means
The average value of the number of hydroxyl groups esterified with a polybasic acid per unit of glucose. That is, when all three hydroxyl groups in one glucose unit are substituted, the degree of substitution has a maximum value of 3.

In the present invention, a polybasic acid monoester derivative of a polysaccharide having a substitution degree of 0.001 to 0.5 is suitable, and more preferably 0.005 to 0.3. If the degree of substitution is less than 0.001, the developing ink of the present invention is not suitable because the emulsion stability and water retention cannot be sufficiently obtained.

Further, if the degree of substitution exceeds 0.5, not only is it difficult to synthesize the derivative of the polysaccharide, but also the improvement of the emulsifying property of the developing ink is not observed.

(Development ink for lithographic printing plate) The development ink of the present invention comprises I. water phase, II. Oil phase, and III. Surfactant, and the oil phase is emulsified and dispersed in the nest phase by the surfactant. It is prepared by Hereinafter, each component will be described.

I. Aqueous Phase I) Polysaccharide Polybasic Acid Monoester Derivative The content of the above-mentioned polysaccharide polybasic acid monoester derivative contained in the aqueous phase of the developing ink of the present invention is preferably 0.1 to 30% by weight, and more preferably It is preferably 0.3 to 25% by weight. When the content is less than 0.1% by weight, the effect of using it will decrease, and as it exceeds 30% by weight, the oil sensitivity of the image area will decrease, and a satisfactory ink density will be obtained at the start of printing. It is necessary to print a large number of prints before the prints having the prints are obtained.

In addition to this, the developing ink of the present invention may contain various known components, if necessary. The components will be described below.

B) Water-soluble salts of polyvalent metals Various water-soluble salts of polyvalent metals can be added to the developing ink of the present invention.

As the water-soluble salts of polyvalent metals, phosphates of polyvalent metals such as calcium, magnesium, nickel, zinc, copper, tin, barium, manganese and molybdenum are used, but especially phosphorus of magnesium, calcium, zinc and barium. Acid salts are preferred.

Further, when the amount of the water-soluble salt of a polyvalent metal is increased, depending on the kind of the polysaccharide derivative, it may become cloudy and gel in some cases. Therefore, the content of polyvalent metal ions depends on the type of polysaccharide derivative, but is generally 0.1 to 50% of that of the polysaccharide derivative.
Degree (equivalent to equivalent of carboxylic acid of polysaccharide derivative)
Is preferred.

C) Water-soluble resin Various other water-soluble resins can be added to the developing ink of the present invention.

For example, natural polymers include starches such as cane starch, potato starch, tapioca starch, wheat starch and corn starch, carrageenan, laminaran, sea soup mannan, furi, iriash moss, agar and those obtained from algae such as sodium alginate, Trolooi, Vegetable mucilages such as mannan, quince seed, pectin, tragacanth gum, karaya gum, xanthine gum, guar gum, locust bingham, gum arabic, carop gum and benzoin gum, homopolysaccharides such as dextran, glucan and levan, and succinoglucan and xanthan gum. Microbial mucilage such as heteropolysaccharide, glue,
Examples thereof include proteins such as gelatin, casein and collagen. Semi-natural products (semi-synthetic products) include propylene glycol alginate, viscose, methyl cellulose, ethyl cellulose, methyl ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl ethyl cellulose and hydroxypropyl methyl cellulose phthalate. Examples thereof include fibrin derivatives and processed starch. Processed starches include roasted starches such as white dextrin, yellow dextrin and british gum, enzyme-modified dextrins such as enzyme dextrin and Schardinger dextrin, acid-decomposed starch shown in solubilized starch, and oxidized starch shown in dialdehyde starch. , Pregelatinized starch such as modified pregelatinized starch and non-modified pregelatinized starch, phosphate starch, fatty starch, sulfate starch, nitrate starch, esterified starch such as xanthate starch and carbamic acid starch, carboxyalkyl starch, hydroxyalkyl starch Etherified starch such as sulfoalkyl starch, cyanoethyl starch, allyl starch, benzyl starch, carbamylethyl starch and dialkylamino starch, methylol crosslinked starch, hydroxyalkyl crosslinked starch, phosphoric acid crosslinked starch and dicarboxylic acid crosslinked starch Crosslinked starch, starch polyacrylamide copolymer, such as, starch polyacrylic acid copolymer,
Starch polyvinyl acetate copolymer, starch polyacrylonitrile copolymer, cationic starch polyacrylic acid ester copolymer, cationic starch vinyl polymer copolymer, starch polystyrene maleic acid copolymer, starch polyethylene oxide copolymer, etc. And the starch graft copolymer of Synthetic products include polyvinyl alcohol other than partially acetalized polyvinyl alcohol, modified polyvinyl alcohol such as allyl-modified polyvinyl alcohol, polyvinyl methyl ether, polyvinyl ethyl ether and polyvinyl isobutyl ether, sodium polyacrylate, partially saponified polyacrylate ester, polyallyl Acid ester copolymer partially saponified product, polyacrylic acid derivative such as polymethacrylic acid salt and polyacrylic amide and polymethacrylic acid derivative, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, copolymer of polyvinylpyrrolidone and vinyl acetate, carboxy Examples thereof include vinyl polymers, styrene-maleic acid copolymers, and styrene-crotonic acid copolymers.

These water-soluble resins may be used in combination of two or more, and may be contained in the developing ink of the present invention in an amount of 20% by weight or less.

D) Wetting agent It is preferable that the aqueous phase further contains a wetting agent.
Thereby, the property that the aqueous phase of the developing ink of the present invention is appropriately spread to the non-image area of the lithographic printing plate can be imparted. Preferred examples of such a wetting agent are polyhydric alcohols, and specific preferred examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, tetraethylene glycol, polyethylene glycol, and diethylene glycol. Propylene glycol, tripropylene glycol, glycerin, sorbitol, pentaerythritol and the like can be mentioned, and glycerin is particularly preferable. The wetting agent is about 0.5 to about 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the developing ink of the present invention.
It can be used in the range of.

E) PH adjusting agent The developing ink of the present invention generally has an acidic region, that is, a pH of 2.
It is advantageous to use it in the range of 0 to 6.0.

In order to adjust the pH value to 2.0 to 6.0, mineral acid, organic acid, inorganic acid, alkali agent or the like is generally added to the developing ink to adjust the pH value. The amount added is 0.01 to 3% by weight. Examples of the mineral acid include nitric acid, sulfuric acid, phosphoric acid and the like.

Organic acids include citric acid, acetic acid, oxalic acid, malonic acid, p
-Toluenesulfonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, phytic acid, benzoic acid, butyric acid, maleic acid, picolinic acid, organic phosphonic acid and the like.

Examples of the inorganic acid salts include nitric acid, phosphoric acid, sulfuric acid, acetic acid molybdate, polyphosphoric acid, boric acid, and the like, and water-soluble alkali metal salts and ammonium salts thereof. For example, sodium nitrate, potassium nitrate, ammonium nitrate, first sodium phosphate, second sodium phosphate, third sodium phosphate, first potassium phosphate, second potassium phosphate, third potassium phosphate, first ammonium phosphate, Dibasic ammonium phosphate, tertiary ammonium phosphate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium molybdate, potassium molybdate, ammonium molybdate, sodium acetate, potassium acetate, ammonium acetate, sodium tripolyphosphate, sodium hexametaphosphate, pyroline Examples thereof include sodium acid salt, sodium borate, potassium borate, ammonium borate and the like.

Examples of the alkaline agent include alkali metals such as sodium hydroxide, potassium hydroxide and lithium hydroxide or hydroxides thereof, and amines such as ammonia monoethanolamine, diethanolamine and triethanolamine.

1 type or 2 types of mineral acid, organic acid, inorganic salt, and alkaline agent
You may use together 1 or more types.

F) Preservative In addition to the above, a preservative and the like can be added to the developing ink of the present invention. For example, benzoic acid and its derivatives, phenol, formalin, sodium dehydroacetate, etc.
It can be added in the range of 005 to 2.0% by weight.

II. Oil phase a) Colorant The colorant is a colorant after the oil phase contained in the developing ink of the present invention adheres to the image area of the lithographic printing plate to evaporate the solvent.
It is used to provide visual contrast to non-image areas and can be selected from a wide range of dyes and pigments. Carbon black can be mentioned as a preferable example. The colorant is contained in the oil phase in an amount to give a desired concentration, but is about 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, based on the total weight of the developing ink of the present invention. Used in the range.

(B) Water-immiscible volatile solvent As the volatile solvent, water-immiscible ones can be used, but more preferably those which do not adversely affect the image area of the lithographic printing plate and have low toxicity. Chosen from. Preferable specific examples of the volatile solvent include hydrocarbon solvents having a boiling point of 120 ° C to 250 ° C in petroleum distillates such as turpentine oil, xylene, toluene, n-heptane, solvent naphtha, kerosene and mineral spirits. These may be used alone or in combination of two or more.

Further, with these volatile solvents, for example, cyclohexanone, ketones such as methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, glycol ethers such as ethylene glycol monophenyl ether, ethers such as phenyl glycol, such as acetic acid. Butyl, amine acetate, and other esters, for example, benzyl alcohol, amyl alcohol, and other alcohols, for example, ethylene chloride, trichloroethylene, and other halogenated hydrocarbons can be used in combination, whereby a lipophilic resin and a sensitizer can be used. Can be easily dissolved, or the aqueous phase and the oil phase can be easily emulsified.

The solvent is about 0.3-based on the total weight of the developing ink of the present invention.
It is used in the range of about 30% by weight, more preferably 0.5 to 25% by weight. In addition, the latter solvent (that is, the solvent used in combination with the hydrocarbon solvent) is about 5 to the total weight of the solvent.
It is used in a range such that it accounts for not more than wt%, more preferably 2-3 wt%.

C) Lipophilic resin A lipophilic resin can be further added to the oil phase. Any lipophilic resin may be used as long as it can be dissolved in a solvent, and a resin used as a vehicle in a lithographic printing plate ink is particularly preferable. For example, rosin, for example, maleica rosin (rosin / maleic anhydride adduct), modified rosin such as water-added rosin, petroleum resin such as Gilsonite, epoxy resin, polyvinyl formal, polyvinyl butyral, phenol resin,
Alkyd resin and modified alkyd resin, rubber modified product, unsaturated polyester, amino resin, polyurethane resin, epoxy resin, styrene resin and copolymer resin thereof, vinyl chloride resin and copolymer resin thereof, vinyl acetate resin and copolymer thereof Polymer resin, acrylic resin and its derivative resin,
Alternatively, a copolymer resin thereof or the like can be used. A particularly useful binder is petroleum resin.

The resin may be used alone or in combination of two or more, and the amount thereof is in the range of about 0.05 to about 10% by weight, more preferably 0.1 to 8% by weight based on the total weight of the developing ink of the present invention. is there.

D) Oil Sensitizer As the oil sensitizer, a compound soluble or dispersible in a solvent is used. Specific preferred compounds include, for example, fatty acids such as caproic acid, enanthic acid, caprylic acid, herargonic acid, capric acid, undecylic acid, lauric acid, tridecyl acid, myristic acid, pentadecyl acid,
Palmitic acid, heptadecyl acid, stearic acid, nanodecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, melissic acid, laxeric acid, saturated fatty acids such as isovaleric acid, acrylic acid, crotonic acid, Of isocrotonic acid, undecylenic acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, prasidic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearolic acid, iwasic acid, taricillic acid, licanoic acid, etc. There are unsaturated fatty acids. More preferred are fatty acids which are liquid at 50 ° C., more preferred are those having 5 to 25 carbon atoms, and most preferred are those having 8 to 21 carbon atoms.

Examples of the plasticizer include dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate and di (2-
Ethylhexyl) phthalate, dinonyl phthalate, digisil phthalate, dilauryl phthalate, butylbenzyl phthalate and other phthalic acid diesters such as dioctyl adipate, butyl glycol adipate, dioctyl azelate, dibutyl sebacate, di (2-ethylhexyl) sebacate, Aliphatic dibasic acid esters such as dioctyl sebacate, for example, epoxidized triglycerides such as epoxidized soybean oil, for example, tricresyl phosphate, trioctyl phosphate, phosphates such as trischloroethyl phosphate,
For example, a plasticizer having a freezing point of 15 ° C. or lower and a boiling point of 300 ° C. or higher at 1 atm, such as benzoic acid esters such as benzyl benzoate, is included.

These oil sensitizers may be used alone or in combination of two or more, and the amount used is 0.001 to 5% by weight, more preferably 0.005 to 1% by weight, based on the total weight of the developing ink of the present invention. It is a range.

III. Surfactant The surfactant is used for emulsifying the water phase and the oil phase of the developing ink of the present invention to obtain a stable emulsion, but it is substantially the oil phase and the water phase. It is distributed and configured. Anionic surfactants and nonionic surfactants are effective as the surfactants used. Examples of anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonate salts, alkylnaphthalene sulfonate salts, dialkylsulfosuccinic acid ester salts, alkyl phosphoric acid ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate ethylene salts. Salting, α-olefin sulfonates, N-lauroyl sarcosine salts Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxy Ethylene sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene, polyoxypropylene block polymers, polyoxy fatty acid esters Emissions acids, pentaerythritol fatty acid esters, small sugar fatty acid esters, amine oxides and the like. Among these, the nonionic surfactant having an HLB of 8 or less is particularly effective.

The amount used is 0.1 with respect to the total weight of the developing ink of the present invention.
-5% by weight, more preferably 0.3 to 3% by weight, a stable emulsion can be obtained.

(Method for adjusting developing ink) Next, a typical method for preparing the developing ink of the present invention will be described.

As a method for preparing the aqueous phase, the above polybasic acid monoester derivative of the polysaccharide and, if necessary, other water-soluble polymer are dissolved in pure water. A wetting agent and an antiseptic agent are sequentially added, and the pH is adjusted to 2 to 4 by adding an appropriate amount of a pH adjusting agent. Separately, the resin is dissolved in the solvent of the oil phase, the colorant and the surfactant are added thereto, and the mixture is sufficiently mixed and dispersed by using a ball mill, a roll mill, a colloid mill, a high speed mohogenizer or the like to adjust the oil phase. If necessary, an oil sensitizer is further added to prepare an oil phase.

While stirring the aqueous phase with a stirrer, the oil phase was added dropwise to the dispersion to obtain a dispersion, which was then emulsified through a homogenizer to obtain the developing ink of the present invention.

(Lithographic printing plate) The developing ink of the present invention can be effectively used for a lithographic printing plate obtained by any method, but in particular, a photosensitive printing plate (presensitized plate) having an aluminum plate as a support is used. (Presensitized plate), abbreviated as PS version. ] Is used for a lithographic printing plate obtained by imagewise exposure and development, a particularly excellent effect is obtained.

The preferred PS version is, for example, British Patent No. 1,35
A photosensitive layer comprising a mixture of a diazo resin (a salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and shellac as described in 0,521 is provided on an aluminum plate, British Patent No. 1,460,978. No. 1,505,739, and a photosensitive layer made of a mixture of a diazo resin and a polymer having a hydroxyethyl methacrylate unit or a hydroxyethyl acrylate unit as a main repeating unit is provided on an aluminum plate. Negative enemy PS version such as the one described above, and o- as described in JP-A-50-125,806.
It includes a positive PS plate in which a photosensitive layer made of a mixture of a quinonediazide photosensitive material and a novolac type phenolic resin is provided on an aluminum plate.

Further, PS plate having a photosensitive layer of a photocrosslinkable photopolymer as specifically shown in U.S. Pat.No. 3,860,426 on an aluminum plate, U.S. Pat.Nos. 4,072,528 and 4,072,527. PS plate having a photosensitive layer of a photopolymerizable photopolymer composition as described in the specification provided on an aluminum plate, British Patent Nos. 1,235,281 and 1,4
A PS plate having a photosensitive layer made of a mixture of azide and a water-soluble polymer as described in each specification of 95,861 provided on an aluminum plate is also preferable.

(Example of use of developing ink) Next, an example of use of the developing ink of the present invention in the case of using a PS plate will be described.

First, the PS plate is imagewise exposed and then developed to prepare a lithographic printing plate.

The developer used in the above-mentioned development processing step is an alkaline solvent containing water as a main solvent, and may contain an alkaline solvent, an organic solvent, an anionic surfactant, an inorganic salt and the like, if necessary.

As the alkaline agent, an inorganic alkaline agent such as sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium triphosphate, sodium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, or a monoalkaline agent. Organic alkaline agents such as, di- or triethanolamine or propanolamine are advantageously used. The content of the alkaline agent in the developer is preferably 0.05 to 4% by weight, more preferably 0.1 to 2% by weight.

As the organic solvent, alcohols such as n-propyl alcohol and pendyl alcohol, and glycol ethers such as phenyl cellosolve are useful. The content of the organic solvent in the developer is preferably 0.5 to 15% by weight, more preferably 1 to 5% by weight.

Examples of the anionic surfactant include alkyl sulfate salts such as sodium lauryl sulfate, alkyl allyl sulfonates such as dodecylbenzene sulfonic acid, and sulfones of dibasic fatty acid esters such as sodium di (2-ethylhexyl) sulfosuccinate. Examples of the acid salts include alkylnaphthalene sulfonates such as sodium n-butylnaphthalene sulfonate and polyoxyethylene alkyl (phenol) ether sulfates. Among these, alkylnaphthalene sulfones such as n-butylnaphthalene sulfonic acid. Acid salts are preferably used. The content of the anionic surfactant in the developing solution is preferably 0.1 to 5% by weight, more preferably 0.5 to 1.5% by weight.

As the inorganic salt, phosphoric acid, silicic acid, carbonic acid, water-soluble salts of alkali or alcalous earth such as sulfite,
In particular, alkali or alkaline earth sulfite is preferably used. The content of the inorganic salt in the developer is in the range of 0.05 to 5% by weight, more preferably 0.1 to 1% by weight.

It is also useful to further contain a defoaming agent, a wetting agent, etc. in the developing solution if necessary.

As a method for developing the PS plate imagewise exposed with the above-mentioned developing solution, various conventionally known methods can be used. Specifically, a method of immersing the image-exposed PS plate in a developer,
A method of spraying the developing solution onto the photosensitive layer of the PS plate from a number of nozzles, a method of wiping the photosensitive layer of the PS plate with a sponge moistened with the developing solution, and a roller coating of the developing solution on the surface of the photosensitive layer of the PS plate. Method etc. are mentioned.

This lithographic printing plate developed by the above-mentioned developing method is washed with water and squeezed with water on the plate surface, and then the developing ink of the present invention is poured onto the plate surface in an appropriate amount, and the developing ink is applied to the entire surface of the plate with a sponge. To do. As a result, the oil phase of the developing ink uniformly adheres only to the image area on the plate surface, the solvent of the oil phase evaporates, and the image area is visualized. Next, the plate surface is washed with water to complete the processing step with the developing ink. After this, if necessary, erase unnecessary image areas formed on the plate,
When printing is not started immediately, for example, an aqueous solution of gum arabic is applied to protect the non-image area, and the lithographic printing plate is stored. Alternatively, an automatic developing ink dispenser can be used.

When the printing is started immediately, the developing ink adhering to the image area is removed by using the solvent of the component (a) or the like, and then the printing is started according to the usual procedure.

Hereinafter, the present invention will be described in more detail based on examples.
In addition, "part" shall mean a "weight part."

Example 1 Petroleum resin (Petrosin # 80 manufactured by Mitsui Petrochemical Co., Ltd.) 10 in a mixed solvent of 155 parts of turpentine oil and 30 parts of cyclohexaton.
Parts were dissolved. Dissolve 15 parts of sorbitan monostearate (product name: Span 60, manufactured by Kao Atlas Co., Ltd.) and 5 parts of sorbitan monooleate (product name: nonion op-80, manufactured by NOF CORPORATION) in this solution, and make a porcelain container. Then add 20 parts of asphalt powder and 15 parts of carbon black to 20 ~
It was ball-milled for 24 hours (dispersion A). Separately, 20 parts of an octenylsuccinic acid derivative of waxycorn starch (degree of substitution 0.01 20 ° C., 20 wt% viscosity 40 cps) was dissolved in 52.59 parts of pure water, and 2 parts of glycerin, 0.1 part of phosphoric acid and 0.01 part of sodium phosphate monobasic acetate were added. Added and dissolved (aqueous solution B).

While stirring the aqueous solution B (total amount) with a stirrer, 25 parts of the completely dispersed dispersion A was slowly dropped and dispersed, and then passed through a homogenizer to form an emulsion, thereby preparing the developing ink (1) of the present invention.

The positive type photosensitive lithographic printing plate described in Example 1 of JP-A-50-125806 (Japanese Patent Application No. 49-33264) is imagewise exposed and developed by the method described in Example 1. And washed with water. A small amount of the above-mentioned developing ink was dropped on the planographic printing plate, and this was spread over the entire plate with a sponge and applied. Then, when the plate was washed with water, the developing ink in the non-image area was washed away, the oil phase of the developing ink adhered only to the image area, and a black image was formed on the white background of aluminum. The original picture was faithfully reproduced without the occurrence of karami. This plate was coated with a 14 ° B aqueous solution of gum arabic, buff dried and stored for 1 month. The plate after storage was washed with water to remove gum arabic, and then the developing ink adhering to the image area was removed with a solvent naphtha. Then, the plate was mounted on a printing machine and printed. A printed matter was obtained. The developing ink (1) was used after being stored in the hermetically sealed container for 1 year, and the same result was obtained.

Example 2 Both solutions having the following formulations were prepared in the same manner as in Example 1 to obtain the developing ink (2) of the invention.

Aqueous phase part Pure water 56.9 parts Wax corn starch octenyl succinic acid derivative (degree of substitution
0.014, 20 ° C., 20 wt% viscosity 40 cps) 17 parts Arabic gum 3 parts Phosphoric acid (85%) 0.3 parts Sodium molybdate 0.3 parts Obtained using this developing ink (2) in the same manner as in Example 1. When used for a lithographic printing plate, the same result as in Example 1 was obtained.

Example 3 A developing ink (3) having the following composition was prepared in the same manner as in Example 1.

Aqueous phase Pure water 52.25 parts Waxycorn starch hexenyl succinic acid derivative (degree of substitution
0.009, 20 ° C., 20 wt% viscosity 30 cps) 16 Yellow dextrin 3 Glycerin 2 Phosphoric acid 0.4 Sodium hexametaphosphate 0.3 Magnesium phosphate 0.05 In Example 1 of JP-A-50-118802 (Japanese Patent Application No. 49-23940). When the above-described developing ink was used for the lithographic printing plate obtained by imagewise exposing and developing the negative-working photosensitive lithographic printing plate described in Example 1 above, The same result as in the above case was obtained.

The same operation was carried out for the developer ink (3) stored for one year, but no change in performance was observed.

Example 4 In the same manner as in Example 1, a developing ink (4) having the following composition was obtained.

Aqueous phase part Pure water 52.8 parts Waxycorn starch Dodecenyl succinic acid derivative (Substitution degree 0.
011, 20 ° C., 20 wt% viscosity 50 cps) 16 gum arabic (14 ° B aqueous solution) 2 yellow dextrin 1 hexylene glycol 0.2 phosphoric acid (85%) 0.5 sodium citrate 0.3 sodium sulfate 0.2 As used in Example 3 When the developing ink (4) was used for the same planographic printing plate, good results were obtained as in the case of Example 1.

Example 5 A developing ink (5) having the following composition was obtained in the same procedure as in Example 1.

Aqueous phase Pure water 53.5 parts Waxycorn starch octenyl succinic acid derivative (degree of substitution
0.1, particle size 20 ° C., 20 wt% viscosity 30 cps) 15 Enzymatic degradation dextrin (Amicol # 1 manufactured by Nitto Kagaku Co., Ltd.) 5 Phosphoric acid 0.5 Ammonium borate 0.5 Potassium acetate 0.5 The planographic printing plate used in Example 1 and Examples The developing ink (5) was used for both of the lithographic printing plates obtained in No. 3, and in each case, the same results as in Example 1 were obtained.

〔The invention's effect〕

 The developing ink of the present invention has the following effects.

(1) There is no occurrence of karami. In particular, a halftone image area on the lithographic printing plate corresponding to a portion of the printed matter having a high image density (the area of the non-image area per unit area is much smaller than that of the image area, and the color is easily generated. ) Also has excellent performance that there is no occurrence of karami.

(2) A visible image that faithfully reproduces the image area on the planographic printing plate is provided. Therefore, it is advantageous when the halftone image material of the planographic printing plate is magnified and observed with a magnifying glass or the like to examine the quality of the finished planographic printing plate.

(3) Even if stored for a long time, the water phase and the oil phase are not separated and the performance is not deteriorated.

(4) When applied to the lithographic printing plate, it can be applied by using a sponge, so the operation is easy and the work efficiency is increased.

(5) It can be easily used even by coating using an automatic developing ink dispenser, and can easily wash sponges and the like using a developing ink dispenser.

(6) It has no adverse effect on both the image area and the non-image area of the planographic printing plate. For example, the receptivity of the developing ink in the image area is not lowered, and the non-image area is not easily stained with the printing ink.

Front page continued (72) Inventor Shuji Sumitomo 4,000 Kawajiri, Yoshida-cho, Hara-gun, Shizuoka Prefecture Fujisha Shin Film Co., Ltd. (72) Inventor Akira Shinnomiya 1-7-10 Ginza, Chuo-ku, Tokyo Oji National Stock In-house (56) Reference JP-A-54-111902 (JP, A)

Claims (8)

[Claims] 1. An emulsion type lithographic printing plate developing ink comprising an oil phase containing a colorant, an aqueous phase containing a water-soluble polymer compound, and a surfactant. At least one of the above is a polybasic acid monoester derivative of a polysaccharide, a developing ink for a lithographic printing plate. 2. The developing ink for a lithographic printing plate according to claim 1, wherein the polysaccharide is starch. 3. The developing ink for a lithographic printing plate according to claim 2, wherein the starch is a waxy starch. 4. The developing ink for a lithographic printing plate according to claim 1, wherein the polysaccharide is fractionated amylopectin. 5. The developing ink for a lithographic printing plate according to claim 1, wherein the polybasic acid monoester derivative of the polysaccharide is a dibasic acid monoester derivative. 6. A polybasic acid monoester derivative as claimed in claim 1, which is a succinic acid monoester derivative.
Development ink for lithographic printing plate described in the item. 7. The degree of substitution of the polybasic acid monoester derivative is 0.
The developing ink for a lithographic printing plate according to any one of claims 1 to 6, which is 001 to 0.5. 8. The lithographic printing plate development according to claim 1, wherein the aqueous solution viscosity of the polybasic acid monoester derivative is 20 wt% and 500 cps (20 ° C.) or less. ink.