JPS63210179A - Developing ink for lithographic plate - Google Patents

Abstract

PURPOSE:To obtain the title ink which gives a visible image faithfully reproducing an image region, does not cause fill-in, is easy to handle, has excellent stability even after the lapse of time, and provides excellent operating efficiency, by using a polybasic acid monoester derivative of a polysaccharide as an emulsion-stabilizing protective colloid for an aqueous phase. CONSTITUTION:A polysaccharide comprising preferably glutinous starch or fractionated amylopectin is reacted with a polybasic acid such as succinic acid to give a polybasic acid monoester derivative of a polysaccharide (e.g., succinic acid monoesterified starch), having at least one free carboxyl group, if necessary in the form of an alkali metal salt or NH4 salt, having a degree of substitution of 0.001-0.5 and a viscosity of 500cP or lower (in 20wt.% aqueous solution, at 20 deg.C). An oil phase consisting of 0.001-10wt.% coloring agent, such as carbon black, 0.3-30wt.% volatile solvent immiscible with eater, etc. is emulsified and dispersed in an aqueous phase of a pH of 2-4, consisting of 0.1-30wt.% above-mentioned derivative and, if required, 0.1-50wt.% (based on the derivative) water-soluble salt of a polyvalent metal, 20wt.% or less water-soluble resin, etc. through the use of 0.1-5wt.% surface active agent.

Description

[Detailed Description of the Invention] [Background of the Invention] The present invention relates to a developing ink for lithographic printing plates.
In particular, it relates to the emulsion type developing ink.

Lithographic printing is a printing method that skillfully takes advantage of the property that water and oil essentially do not mix.
It consists of an area that repels oil-based ink and an area that repels water and receives oil-based ink, the former being called a non-image area and the latter being an image area.

The purpose of developing ink for lithographic printing plates is to make it easier to visually distinguish between image areas and non-image areas of a lithographic printing plate, and at the same time to attach a lipophilic substance to the image areas to increase the receptivity of printing ink. Furthermore, it is applied to the lithographic printing plate in order to protect the image area during various subsequent operations such as gumming.

It goes without saying that such a developing ink must have the above-mentioned properties, but it also needs to have the following properties.

(1) Even when the developing ink is applied to a halftone image formed on a lithographic printing plate, so-called coloring (i.e.,
A phenomenon in which the lipophilic substance contained in the developing ink adheres so as to bridge between adjacent halftone dots or to cover a minute non-image area surrounded by an image area. . ) shall not occur.

(2) The colored image visualized by the developing ink faithfully reproduces the image area formed on the lithographic printing plate (for example, there is no drawback that the visualized halftone dots are thicker than the actual halftone dots). ).

(3) The developing ink itself has excellent stability over time (that is, the property that the performance immediately after manufacture is maintained even after a long period of 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 special equipment.

Conventionally known developing inks, such as Chinfuta, satisfied some of the above-mentioned performances, but
None of these satisfied all of them.

[Purpose of the invention]

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

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

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

Yet another object of the present invention is to provide a developer ink that can be applied with simple tools onto a lithographic printing plate.

[Structure of the invention]

In order to achieve the above objectives, the present inventors have conducted various studies and found that a polybasic acid monoester derivative of a polysaccharide is used as a protective colloid substance for emulsion stabilization to be used in the aqueous phase of a developing ink for lithographic printing plates. The present invention has been accomplished based on the discovery that the above object can be specifically achieved by using the following.

That is, the present invention provides a developing ink for emulsified planographic printing plates comprising an oil phase containing a colorant, an aqueous phase containing a water-soluble polymer compound, and a surfactant. A developing ink for a lithographic printing plate, wherein at least one of the above is a polybasic acid monoester derivative of a polysaccharide.

The present invention will be explained in detail below.

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

Homoglycans include (i) glucan: cellulose, starch, clicogen, caronine, laminaran, dextran;

(ii) Fructans: inulin, levan.

(iii) Mannan: Elephant palm mannan.

(iv) Xylan: xylan from rice straw.

(V) Galacturonan: Pectic acid.

(vi) Mannuronan: alginic acid.

(vii) N-acetylglucosamine polymer: chitin.

As heteroglycans (i) Diheteroglycan: guaran, konnyaku (7)
7-nannan, heparin, chondroitin sulfate, hyaluronic acid.

(ii)) Liheteroglycans: Meskit gum, Gatchi gum, and many other plant mucilages, gums, bacterial polysaccharides.

(iii) Tetraheteroglycans: gum arabic, hemp seed mucilage, many other mucilages, rubbery bacterial polysaccharides.

Some of the above polysaccharides are not water-soluble as they are, but they can be used in the present invention if made water-soluble by making them into polybasic acid monoester derivatives.

In addition, from an economic point of view, it is preferable to use starch-based materials, such as those obtained from potatoes, sweet potatoes, wheat, corn, rice, tapioca, glutinous corn (waxy corn), glutinous rice, etc. Particularly preferred are glutinous seed starch (glutinous rice, glutinous corn, waxy corn) and fractionated amylopectin with a high amylopectin content.

An advantage of amylopectin-type starch is that it is less susceptible to the aging phenomenon that is characteristic of starch, so it is advantageous in terms of stability over time.

(Polybasic acid) Polybasic acids that can be suitably used in the present invention are illustrated 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, hexaisobutynylsuccinic acid, nonylsuccinic acid, n-octylsuccinic acid, 2-ethyl-2-methylsuccinic acid, dimethylbenzylsuccinic acid, octenylsuccinic acid, hexenylsuccinic acid, decynylglutaric acid, dodecenylsuccinic acid, etc. Among these, particularly preferred are succinic acids such as octenylsuccinic acid.

(Polybasic acid monoester derivative of polysaccharide) The polybasic acid monoester derivative of polysaccharide used in the present invention can be advantageously obtained by esterifying the above polysaccharide using the anhydride of the above polybasic acid. can.

Preferred examples of polybasic acid monoester derivatives of polysaccharides used in the present invention include co/S phosphoric acid monoesterified starch, octenylconoester monoesterified starch, hexenylsuccinic acid monoesterified starch, and decynylglutaric acid monoesterified starch. Examples include monoesterified starch, dodecenylsuccinic acid monoesterified starch, maleic acid monoesterified starch, and the like.

Among these, succinic and acid monoesterified starches such as octenylsuccinic acid monoesterified starch exhibit particularly preferable effects.

Furthermore, the polybasic acid monoester derivative of polysaccharide used in the present invention has one or more free carboxylic acid groups, and if necessary, an alkali metal salt such as sodium, potassium, or lithium or an ammonium salt may be added. It is also suitably used as

The preferred range of viscosity of the polybasic acid monoester derivative of polysaccharide used in the present invention is 50 Q in a 20% by weight aqueous solution.
cps or less [B-type viscometer BL type, manufactured by Tokyo Keiki ■, 20℃
], and more preferably 300 cps or less. In general, if the viscosity is 50 Qcps or more, the developing ink cannot be quickly applied to the image area when applying the developing ink either by hand or by an automatic developing inking machine, and color unevenness tends to occur, making plate inspection difficult. A more preferable range of 30 Qc
ps or less is particularly effective for solving these problems.

Methods for adjusting the viscosity include heating roasting, enzymatic modification, acidic modification, oxidative modification, etc., and the viscosity can be adjusted to the required value by adjusting reaction conditions such as temperature, time, composition, etc.

In general, polysaccharide derivatives have a change (denaturation) in the chemical structure of the glucose unit in the polysaccharide molecule, and the degree of denaturation, that is, the degree of substitution ([]egree of
tion) is extremely important for suppressing aging and gelation of polysaccharides, improving water retention, and strengthening hydrophilicity or lipophilicity. In this specification, the degree of substitution refers to the average number of hydroxyl groups esterified with a polybasic acid per unit of glucose. That is, when all three hydroxyl groups in one unit of glucose are substituted, the degree of substitution has a maximum value of 3.

In the present invention, the polybasic acid monoester semiconductor device conversion degree of the polysaccharide is preferably 0.001 to 0.5, but
More preferably, it is 0.005 to 0.3.

If the degree of substitution is less than 0.001, the developing ink of the present invention will not have sufficient emulsion stability or water retention, which is inappropriate.

Furthermore, if the degree of substitution exceeds 0.5, not only will it be difficult to synthesize polysaccharide derivatives, but also no improvement in the emulsifying properties of the developing ink will be observed.

(Developing ink for lithographic printing plates) The developing ink of the present invention consists of (1) an aqueous phase, (2) an oil phase, and (3) a surfactant, and the surfactant emulsifies and disperses the oil phase in the aqueous phase. It is prepared by letting. Each component will be explained below.

1. Aqueous phase a) Polybasic acid monoester derivative of polysaccharide The content of the polybasic acid monoester derivative of polysaccharide contained in the aqueous phase of the developing ink of the present invention is preferably 0.1 to 30% by weight. , more preferably 0.63 to 25% by weight. As the content decreases below 0.1% by weight, the effect of using it decreases, and as the content exceeds 30% by weight, the oil sensitivity of the image area decreases, making it difficult to obtain a satisfactory ink at the start of printing. A large number of prints must be printed before a print with density is obtained.

In addition, the developing ink of the present invention may contain various known components as required. The components are described below.

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

Phosphates of polyvalent metals such as calcium, magnesium, nickel, zinc, copper, tin, barium, manganese, and molybdenum are used as water-soluble salts of polyvalent metals, but in particular, phosphates of magnesium, calcium, zinc, and barium are used. Salt is preferred.

Furthermore, depending on the type of polysaccharide derivative when the amount of the water-soluble salt of the polyvalent metal is increased, it may become cloudy and may even become gelled. Therefore, although the content of polyvalent metal ions depends on the type of polysaccharide derivative, it is generally 0.1 to 5% of the polysaccharide derivative.
About 0% (equivalent to the equivalent of the carboxylic acid of the polysaccharide derivative) is preferable.

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 kansho starch, potato starch, tapioca starch, wheat starch, and corn starch, and starches obtained from algae such as carrageenan, laminaran, seaweed mannan, funori, iriash moss, agar, and sodium alginate. Vegetable mucilages such as yellow mallow, mannan, quince seed, pectin, gum tragacanth, gum karaya, xanthine gum, guarbing gum, locust bingham, gum arabic, gum calops and gum benzoin, homopolysaccharides such as dextran, glucan and levan, and succinoglucan and microbial mucilages such as heteropolysaccharides such as xanthan gum, glue, proteins such as gelatin, casein, and collagen. In addition to alginate propylene glycol ester, semi-natural products (semi-synthetic products) include viscose, methylcellulose, ethylcellulose, methylethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxypropylethylcellulose, and hydroxypropylmethylcellulose. Examples include cellulose derivatives such as phthalates and processed starches. Processed starches include roasted starches such as white dextrin, yellow dextrin, and British ash gum, enzyme-modified butostrins such as enzyme dextrin and Schardinger dextrin, acid-decomposed starches as shown in solubilized starch, oxidized starches as shown in dialdehyde starch, Pregelatinized starch such as modified pregelatinized starch and unmodified pregelatinized starch, esterified starch such as phosphate starch, fatty starch, sulfate starch, nitrate starch, xanthate starch and carbamate starch, carboxyalkyl starch, hydroxyalkyl starch, Etherified starches such as sulfoalkyl a powder, cyanethyl starch, allyl starch, benzyl starch, carbamylethyl starch and dialkylamino starch, methylol cross-linked starch, hydroxyalkyl cross-linked starch, phosphoric acid cross-linked starch and dicarboxylic acid cross-linked starch, etc. Cross-linked starch, starch polyacrylamide copolymer, starch polyacrylic acid copolymer, starch polyvinyl acetate copolymer, starch polyacrylonitrile copolymer, cationic starch polyacrylic acid ester copolymer, cationic starch vinyl polymer copolymer Examples include starch graft copolymers such as starch polystyrene maleic acid copolymers and starch polyethylene oxide copolymers. Synthetic products include partially acetalized polyvinyl alcohol, allyl-modified polyvinyl alcohol, modified polyvinyl alcohol such as polyvinyl methyl ether, polyvinylethyl ether, and polyvinyl isobutyl ether, poly(sodium acrylate), partially saponified polyacrylic ester, Partially saponified polyacrylic acid ester copolymers, polyacrylic acid derivatives such as polymethacrylate and polyacrylamide, polyacrylic acid derivatives, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, copolymerization of polyvinylpyrrolidone and vinyl acetate Coalescence, carboxyvinyl polymer, styrene maleic M
Examples include copolymers, styrene crotonic acid copolymers, and the like.

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

2) Wetting agent Preferably, the aqueous phase further contains a wetting agent.

Thereby, the property can be imparted that the aqueous phase of the developing ink of the present invention spreads appropriately to the non-image areas 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, bentanediol, hexylene glycol, tetraethylene glycol, polyethylene glycol, Examples include propylene glycol, tripropylene glycol, glycerin, sorbitol, and pentaerythritol, with glycerin being particularly preferred. Wetting agents can be used in amounts ranging from about 0.5 to about 10% by weight, more preferably from 1 to 5% by weight, based on the total weight of the developing ink of the present invention.

e) PH adjuster The developing ink of the present invention is generally used in an acidic region, that is, at a pH of
It is advantageous to use a range of 2.0 to 6.0.

In order to adjust the pH value to 2.0 to 6.0, mineral acids, organic acids, inorganic acids, or alkaline agents are generally added to the developing ink. The amount added is 0.01 to 3% by weight. For example, mineral acids include nitric acid, sulfuric acid, phosphoric acid, and the like.

Organic acids include citric acid, acetic acid, oxalic acid, malon if2
, p-) luenesulfonic acid, tartaric acid, malic acid, lactic acid,
Examples include levulinic acid, phytic acid, benzoic acid, butyric acid, maleic acid, picolinic acid, and organic phosphonic acid.

Inorganic acid salts include water-soluble alkali metal salts and ammonium salts thereof such as nitric acid, phosphoric acid, sulfuric acid, molybdate-acetic acid, polyphosphoric acid, and boric acid.

For example, sodium nitrate, potassium nitrate, ammonium nitrate, monosodium phosphate, dibasic sodium phosphate, tertiary sodium phosphate, monobasic potassium phosphate, dibasic phosphate
Potassium, tertiary potassium phosphate, primary ammonium phosphate, secondary ammonium phosphate, tertiary ammonium phosphate, sodium sulfate, potassium sulfate, ammonium sulfate,
Examples include sodium molybdate, potassium molybdate, ammonium molybdate, sodium acetate, potassium acetate, ammonium acetate, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, sodium borate, potassium borate, and ammonium borate.

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

Mineral acids, organic acids, inorganic salts, and alkali agents may be used alone or in combination of two or more.

f) Preservatives In addition to the above, preservatives 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 a range of 0.005 to 2.0% by weight.

(2) Oil phase (a) Colorant The colorant is used after the oil phase contained in the developing ink of the present invention adheres to the image area of the lithographic printing plate and the solvent evaporates.
They are used to provide visual contrast between non-image areas and can be selected from a wide range of dyes and pigments.

A preferred example is carbon black. The colorant is contained in the oil phase in such a range as to give the desired concentration, but approximately 0.00% by weight based on the total weight of the developing ink of the present invention. OO1-10% by weight, more preferably 0.
It is used in a range of 0.01 to 5% by weight.

(1) Volatile solvent that is immiscible with water As the volatile solvent, one that is immiscible with water can be used, but it is more preferable to use one that does not adversely affect the image area of the lithographic printing plate and has low toxicity. selected from. Preferred specific examples of such volatile solvents include hydrocarbon solvents having a boiling point of around 120°C to 250°C, such as turpentine oil, xylene, toluene, n-hebutane, solvent naphtha, kerosene, mineral spirits, etc. These can be used alone or in combination of two or more.

In addition, together with these volatile solvents, ketones such as cyflohexanone and methyl ethyl ketone, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monophenyl ether, and ethers such as phenyl glycol. For example, esters such as butyl acetate and amyl acetate can be used in combination with alcohols such as benzyl alcohol and amyl alcohol, and halogenated hydrocarbons such as tlf ethylene chloride and trichloroethylene, thereby making the lipophilic resin and a fat sensitizing agent can be easily dissolved, or an aqueous phase and an oil phase can be easily emulsified.

The solvent is used in an amount ranging from about 3 to about 30% by weight, more preferably from 5 to 25% by weight, based on the total weight of the developing ink of the present invention. Furthermore, the latter solvent (i.e., the solvent used in combination with the hydrocarbon solvent) is approximately 5% by weight based on the total weight of the solvent.
It is used in an amount of not more than 2% by weight, more preferably 2 to 3% by weight.

c) Lipophilic resin A lipophilic resin can be further added to the oil phase. The lipophilic resin may be any resin as long as it can be dissolved in a solvent, and those used as a vehicle in lithographic printing plate inks are particularly suitable. - Examples include rosins, such as maleica rosin (rosin/maleic anhydride adduct), modified rosins such as water-added rosins, petroleum resins such as giltnite, epoxy resins, polyvinyl formal, polyvinyl butyral, phenolic resins,
Alkyd resins and modified alkyd resins, rubber modified products, unsaturated polyesters, amino resins, polyurethane resins, epoxy resins, styrene resins and their copolymer resins, vinyl chloride resins and their copolymer resins, vinyl acetate resins and their copolymers. Polymer resins, acrylic resins and their derivative resins,
Alternatively, a copolymer resin thereof, etc. can be used. Particularly useful binders are petroleum resins.

The resin can be used alone or in combination of two or more, and the amount used is 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. % range.

2) Liposensitizing agent As the oil sensitizing agent, a compound that is 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, tridecylic acid, myristic acid, pencdecylic acid, palmitic acid, heptadecylic acid, and stearic acid. acids, saturated fatty acids such as nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, melisic acid, roughceric acid, isovaleric acid, and acrylic acid, crotonic acid, incrotonic acid, undecyl acid, oleic acid,
Elaidic acid, cetoleic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linuric acid, arachidonic acid,
Unsaturated fatty acids include propiolic acid, stearolic acid, sardine acid, cririlic acid, and lycanic acid. More preferably, it is a fatty acid that is liquid at 50°C, still more preferably a fatty acid having 5 to 25 carbon atoms, and most preferably a fatty acid having 8 to 21 carbon atoms.

Examples of plasticizers include phthalic acid diesters such as dibutyl phthalate, didecyl phthalate, di-n-octyl phthalate, di(2-ethylhexyl) azelate, dinonyl phthalate, didecyl phthalate, dilauryl phthalate, and butylbenzyl phthalate. , aliphatic dibasic acid esters such as dioctyl adipate, butyl glycol adipate, dioctyl azelate, dibutyl sebacate, di(2-ethylhexyl) sebacate, dioctyl sebacate, epoxidized triglycerides such as epoxidized soybean oil, For example, phosphoric acid esters such as tricresyl phosphate, trioctyl phosphate, and trichloroethyl phosphate, and benzoic acid esters such as benzyl benzoate have a freezing point of 15°C or lower and a boiling point of 300°C at 1 atmosphere. Contains plasticizers above ℃.

These sensitizers can be used alone or in combination of two or more, and the amount used is 0.001 to 5% by weight, more preferably 0.0% by weight based on the total weight of the developing ink of the present invention.
It is in the range of 0.05 to 1% by weight.

(2) Surfactant The surfactant is used to emulsify the water phase and oil phase of the developing ink of the present invention to obtain a stable emulsion. It is distributed and composed of. As the surfactant used, anionic surfactants and nonionic surfactants are effective. For example, anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl ethylene sulfate. Salts, α-olefin sulfonates, N-lauroylsarcosine salts Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene Examples include sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene, polyoxypropylene block polymers, polyoxy fatty acid amines, pentaerythritol fatty acid esters, sucrose fatty acid esters, and amine oxides. Among these, nonionic surfactants having an HLB of 8 or less are particularly effective.

The amount used is 0.00% based on the total weight of the developing ink of the present invention.
A stable emulsion can be obtained at a concentration of 1 to 5% by weight, more preferably 0.3 to 3% by weight.

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

To prepare the aqueous phase, dissolve the polybasic acid monoester derivative of the polysaccharide and other water-soluble polymers as necessary in pure water, add a wetting agent and a preservative in order, and adjust the pH to 2. ~4
Adjust the pH by adding an amount of pH adjuster as needed. Separately, the resin is dissolved in a solvent for the oil phase, a coloring agent and a surfactant are added thereto, and the mixture is sufficiently mixed and dispersed using a ball mill, roll mill, colloid mill, high-speed homogenizer, etc. to prepare an oil phase. Further, if necessary, an oil sensitizing agent is further added to prepare an oil phase.

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

(Lithographic Printing Plate) The developing ink of the present invention can be effectively used for planographic printing plates obtained by any method, but is particularly suitable for photosensitive printing plates having an aluminum plate as a support. (Presensitized pla
te), abbreviated as PS version. ] is used in a lithographic printing plate obtained by imagewise exposure and development, particularly excellent effects can be obtained.

Preferred such PS versions are, for example, British Patent No. L
A photosensitive layer made of a mixture of a diazo resin (salt of a condensate of p-diazodiphenylamine and parapho-2-fluoraldehyde) and shellac as described in No. 350.521 is provided on an aluminum plate; British Patent Nos. 1.460.978 and 1.505.
Negatives such as those in which a photosensitive layer made of a mixture of a diazo resin and a polymer having hydroxyethyl methacrylate units or hydroxyethyl acrylate units as main repeating units as described in the specifications of No. 739 are provided on an aluminum plate. Type PS version, and JP-A-5
This includes a positive PS plate in which a photosensitive layer made of a mixture of an 0-quinone diazide photosensitive material and a novolak type phenol resin is provided on an aluminum plate, as described in Japanese Patent No. 0-125,806.

Further, a PS plate in which a photosensitive layer of a photocrosslinkable photopolymer is provided on an aluminum plate as specifically shown in US Pat. No. 3,860,426, and US Pat.
072.528 and 4.072.527, a PS plate in which a photosensitive layer of a photopolymerizable photopolymer composition is provided on an aluminum plate, British Patent No. 1.235 .281 and 1, 495.8
Also preferred is a PS plate in which a photosensitive layer made of a mixture of azide and a water-soluble polymer is provided on an aluminum plate as described in each specification of No. 61.

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

First, the PS plate is imaged exposed and then developed to create a lithographic printing plate.

The developing solution used in the above development process is an alkaline solvent containing water as a main solvent, and may contain an organic solvent, an anionic surfactant, an inorganic salt, etc. as necessary in addition to the alkaline agent.

Examples of alkali agents include inorganic alkali agents such as sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, tribasic sodium phosphate, sodium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, etc. Organic alkaline agents such as , di- or triethanolamine or propatoolamine 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.

Useful organic solvents include alcohols such as n-propyl alcohol and benzyl alcohol, and glycol ethers such as phenylcellosolve. 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 anionic surfactants include alkyl sulfate ester salts such as lauryl sulfate, IJ sulfate, alkylaryl sulfonates such as dodecylbenzenesulfonic acid, and dibasic acids such as sodium di(2-ethylhexyl)sulfosuccinate. Examples of sulfonates of fatty acid esters include alkylnaphthalene sulfonates such as sodium n-butylnaphthalenesulfonate, polyoxyethylene alkyl (phenol) ether sulfates, etc. Among these, n-butylnaphthalenesulfonic acid Alkylnaphthalene sulfonates such as are preferably used. The content of anionic surfactant in the developer is 0.61
~5% by weight is preferred, and the range from 0.5 to 1.5% by weight is more preferred.

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

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

The image-exposed PS plate is developed with the developer described above. As the method, various conventionally known methods are possible. Specifically, methods include immersing an image-exposed PS plate in a developer, spraying the developer onto the photosensitive layer of the PS plate from multiple nozzles, and using a sponge moistened with the developer to remove the PS plate. Examples include a method of wiping the photosensitive layer, and a method of applying a developer to the surface of the photosensitive layer of the PS plate using a roller.

After washing the lithographic printing plate developed by the above development method and squeezing the water on the plate surface, pour an appropriate amount of the developing ink of the present invention onto the plate surface, and rub with a sponge so that the developing ink is coated on the entire surface of the plate. do. As a result, the oil phase of the developing ink uniformly adheres only to the image area on the printing plate, and the solvent of the oil phase evaporates, making the image area visible. Next, the printing plate is washed with water to complete the processing step with the developing ink. After this, if necessary, erase unnecessary image areas formed on the printing plate,
If printing is not to be started immediately, the non-image areas are protected by applying, for example, an aqueous solution of gum arabic, and the lithographic printing plate is stored. Alternatively, it is also possible to use an automatic developing inking machine.

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

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

In addition, "part" shall mean "part by weight."

Example 1 Petroleum resin (Vetrozin #80 manufactured by Mitsui Petrochemicals) in a mixed solvent of 155 parts of turpentine and 30 parts of cyclohexanone
10 parts were dissolved. Add 15 parts of sorbitan monostearate (trade name Span 60, manufactured by Kao Atlas) and sorbitan monooleate (trade name Nonion OP-80) to this solution.
, Nippon Oil & Fats & Co., Ltd.) was dissolved, placed in a porcelain container, 20 parts of asphalt powder and 15 parts of carbon black were added, and ball milled for 20 to 24 hours (Dispersion A).

Separately, 20 parts of octenylsuccinic acid derivative of waxy corn starch (substitution degree 0.0120°C, 20% by weight viscosity 40 cps) was dissolved in 52.59 parts of pure water, 2 parts of glycerin, 0.1 part of phosphoric acid, monobasic sodium phosphate. 0.3 part of the solution was dissolved, and 0.01 part of sodium dehydroacetate as a preservative was added and dissolved (aqueous solution/liquid 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
The mixture was passed through a homogenizer to form an emulsion, thereby producing the developing ink (1) of the present invention.

Japanese Unexamined Patent Publication No. 125806/1983 (Patent Application No. 1983=332
The positive-working photosensitive lithographic printing plate described in Example 1 of No. 64) was imagewise exposed, developed, and washed with water in the manner described in Example 1.

A small amount of the above-mentioned developing ink was dropped onto the lithographic printing plate, and spread over the entire surface of the plate using a sponge. When washed with water, the developing ink in the non-image areas was washed away, and the oil phase of the developing ink adhered only to the image areas, forming a black image on the white background of the aluminum. There were no blemishes and the original painting was faithfully reproduced. This plate was coated with a 14° BO2 aqueous solution of gum arabic, puff-dried, and stored for one month. After washing the preserved plate with water to remove gum arabic, and then using solvent naphtha to remove the developing ink attached to the image area, this plate was installed in the printing machine and printed. A print was obtained. 1 of the above developing ink (1) in a sealed container
I used it after storing it for a year, and got exactly the same results.

Example 2 Both solutions having the following formulations were prepared in the same manner as in Example 1 to obtain a developing ink [2] of the present invention.

Solvent phase Part aqueous phase
pure water
56.9 parts Octenylsuccinic acid derivative of waxy corn starch (substitution degree 0.014. 20°C, 20% by weight viscosity 40 cPs) 17 parts Gum arabic 3 parts Phosphoric acid (85%)
0.3 parts Sodium molybdate 0.3 parts When this developing ink (2) was used on a lithographic printing plate obtained in the same manner as in Example 1, the results were exactly the same as in Example 1. was gotten.

Example 3 In the same manner as in Example 1, a developing ink (3
) was prepared.

Solvent phase Aqueous phase Pure water 52.25 parts Degree of substitution of waxy corn starch with hexenylsuccinic acid derivative 0.009. 20°C, 20wt% viscosity 30°'s) 16 Yellow dextrin 3 Glycerin
2 Phosphoric acid 0.4 Sodium hexametaphosphate 0.3 Magnesium phosphate 0.05 Negative photosensitivity of 0 described in Example 1 of JP-A-50-118802 (Japanese Patent Application No. 49-23940) When the above developing ink was used on a lithographic printing plate obtained by imagewise exposure and development using the method described in Example 1, the same results as in Example 1 were obtained. The results were obtained.

The same test was conducted using the developing ink (3) that had been 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.

Solvent phase Part aqueous phase
pure water
52.8 parts waxy corn starch Dodecenyl succinic acid derivative Substitution degree 0.011. 20°C, 20% by weight viscosity 50””) 16 Gum arabic (14°B6 aqueous solution) 2 Yellow dextrin 1 Hexylene glycol
0.2 Phosphoric acid (85%) 0.5 Sodium citrate 0.3 Sodium sulfate 0.2 When the above developing ink (4) was used on the same lithographic printing plate used in Example 3, As in Example 1, good results were obtained.

Example 5 A developing ink (5
) was obtained.

Solvent phase Part aqueous phase Pure water 53.5 parts Octenyl succinic acid derivative of waxy corn starch (substitution degree 0.1, particle size 20°C, 20% by weight viscosity 30 cP') 15
Enzyme-degraded dextrin 5 (Amicol #1 manufactured by Nichido Chemical) Phosphoric acid 0.5 Ammonium borate 0.5 Potassium acetate
0.5 The above developing ink (5) was used for both the lithographic printing plate used in Example 1 and the lithographic printing plate obtained in Example 3, but in both cases, the same as in Example 1 was used. Similar results were obtained.

〔Effect of the invention〕

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

(1) There is no occurrence of karami. In particular, halftone image areas on planographic printing plates corresponding to areas with high image density in printed matter (in this area, the area of the non-image area per unit area is much smaller than that of the image area, and smearing is likely to occur). ) also has excellent performance in that there is no occurrence of scorch.

(2) Provide a visible image that faithfully reproduces the image area on the lithographic printing plate. Therefore, it is advantageous to examine the quality of the finished planographic printing plate by enlarging and observing the halftone image of the planographic printing plate using a louver or the like.

(3) Even if stored for a long time, the aqueous phase and oil phase will not separate and there will be no deterioration in performance.

(4) When applying it to a lithographic printing plate, it can be applied using a sponge, which simplifies the operation and improves work efficiency.

(5) It can be easily used for coating using an automatic developing inking machine, and sponges and the like used in developing inking machines can also be easily cleaned.

(6) It does not have an adverse effect on either the image area or the non-image area of the lithographic printing plate. For example, the printing ink receptivity of the image area is not reduced, and the non-image area is not easily smeared with printing ink.

Claims (8)

[Claims] (1) In a developing ink for emulsified planographic printing plates consisting of an oil phase containing a colorant, an aqueous phase containing a water-soluble polymer compound, and a surfactant, a small amount of the water-soluble polymer compound is contained. 1. A developing ink for lithographic printing plates, wherein one of the two types is a polybasic acid monoester derivative of a polysaccharide. (2) The developing ink for lithographic printing plates according to claim 1, wherein the polysaccharide is starch. (3) The developing ink for lithographic printing plates according to claim 2, wherein the starch is glutinous seed starch. (4) The developing ink for lithographic printing plates according to claim 1, wherein the polysaccharide is fractionated amylopectin. (5) The developing ink for lithographic printing plates according to claim 1, wherein the polybasic acid monoester derivative of polysaccharide is a dibasic acid monoester derivative. (6) The developing ink for lithographic printing plates according to claim 1 or 5, wherein the polybasic acid monoester derivative is a succinic acid monoester derivative. (7) Polybasic acid monoester semiconductor device conversion degree is 0.00
1 to 0.5, the developing ink for lithographic printing plates according to any one of claims 1 to 6. (8) The aqueous solution viscosity of the polybasic acid monoester derivative is 20
The developing ink for lithographic printing plates according to any one of claims 1 to 7, which has a developing ink of 500 cps (20°C) or less in weight%.