JPS6023098A - Fat-desensitizing liquid for offset printing - Google Patents

Abstract

PURPOSE:To provide the titled cyan-free desensitizing liquid for offset printing enhanced in film-forming rate, not affected by printing environments and stable for a long period of time, comprising a specified anionic compound, a specified water-soluble cationic polymer and a specified electrolyte. CONSTITUTION:(A) An anionic compound having a molecular weight of not less than about 500 and capable of forming a chelate with zinc ion other than an ammonium salt or amine salt of inositol hexaphosphate, preferably, a phosphate of a polyhydroxyl compound, (B) a water-soluble cationic polymer, preferably, having a molecular weight of 500-100,000, e.g., an aniline resin hydrochloride, and (C) an electrolyte consisting of at least one of alkali (I) metal salts, ammonium salts and amine salts of formic acid, oxalic acid, sulfuric acid, nitric acid, sulfamic acid and carbonic acid and having a solubility in a water at normal temperature of not less than 10wt%, preferably, not less than 20wt%, e.g., AgNO3, are dissolved in water to obtain the objective fat-densitizing liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic offset printing plate surface treatment liquid, and more particularly to a desensitization treatment liquid for neutral-free offset printing that does not contain any cyan compounds.

Electrophotographic offset printing original plate (hereinafter referred to as master)
has a photosensitive layer in which a photoconductive fine powder such as zinc oxide is dispersed in a resin binder, and is obtained by performing ordinary electrophotographic operations on this layer to form a lipophilic image. .

Generally, in offset printing, a plate is used that consists of a non-image area that is easily wetted by water (hydrophilic area) and an image area that is difficult to wet (oleophilic area). Since the image area of the original plate is made of a hydrophobic photoconductive layer, if printing is performed as is, the printing ink will adhere to the non-image area and normal printing will not be possible.

Therefore, prior to printing, it is necessary to desensitize the non-image areas of the printing plate to impart hydrophilic properties. Traditionally, this type of desensitizing treatment liquid includes ferrocyanate, a cyanide compound-containing treatment liquid containing ferricyanide as a main component,
ammine'cobalt agonist, phytic acid and its derivatives,
A cyanide-free treatment solution containing a guanidine derivative as a main component has been proposed.

However, these processing solutions cannot be said to be fully satisfactory processing solutions. That is, in the case of the former treatment solution containing ferrocyanide salt or ferricyanide salt, it has the advantage of having a strong desensitizing power, the ability to form a strong hydrophilic film, and a fast film formation rate. Ferricyanine ions are unstable to heat and light, and when exposed to light, they become colored and precipitate, weakening their desensitizing ability.Furthermore, because they contain cyanide ions (CN), they can be detected as free shea/solids. However, it has the disadvantage of posing various problems in terms of pollution, such as drainage.

On the other hand, taking these points into consideration, cyanide-free processing liquids containing desensitizing agents as the main ingredients have been proposed;
Even with these factors, it cannot be said that the processing solution is capable of producing a fully satisfactory lithographic printing original plate. Specifically, the film formation rate is slower than the former, and the etching method using Prosensor has a
It is not possible to form a hydrophilic film with high physical strength that can be immediately printed by passing it through, and it has the disadvantage of causing scumming and uneven halftone gradation.

Conventionally, it is well known that Inosit hexalic acid ester and its metal derivatives form chelate compounds with metals, and various types of desensitizing agents for offset printing original plates have already been provided.

However, all of these methods have drawbacks such as slow film formation speed and the occurrence of background smudges and narrowed dot gradations.

The present inventors previously reported in Japanese Patent Publication No. 58-5799 that ions of monovalent and divalent metal salts such as sodium phytate, potassium phytate, and calcium phytate of Inozite hexaphosphate and a water-soluble cationic polymer We proposed a complex, but in this case the water retention improved, but
This method has the disadvantage that a satisfactory etching speed cannot be obtained. As a way to improve these shortcomings, further research has revealed that specific electrolytes have been developed for inosit hexaphosphate, its derivatives, and ionic complexes of water-soluble cations and anionic polymers that have the ability to form chelates with zinc ions. The present invention was completed by discovering that the enching speed could be increased by adding a chemical ornament.

That is, the present invention provides (a): a compound having a molecular weight of about 500 other than the ammonium salt or amine salt of inodite hexaphosphate;
The above is an anionic compound having the ability to form a chelate with zinc ions, (b): a water-soluble cationic polymer, and (C):
An electrolyte whose solubility in water at room temperature is 10x7 or more of at least one selected from alkali, metal salt, super-alkali metal salt, ammonium salt, or amine salt of formic acid, oxalic acid, sulfuric acid, nitric acid, sulfamic acid, or carbonic acid. This is a desensitizing liquid for offset printing consisting of figurines.

Examples of anionic compounds having a molecular weight of about 500 or more and having the ability to form chelates with salivary lead ions used in the treatment liquid of the present invention include JP-A No. 57-199694 and JP-B No. 45-246.
Phytic acid or its metal salts described in JP-A-51-103501 and JP-A-54-10003, JP-A-53-83806, JP-A-53 -83807 specification, JP-A-53-10
9701 specification, JP-A-53-127002, JP-A-53-127003 and JP-A-54-4
Inozite hexaphosphate derivatives, vinylphosphonic acid (salt) polymers or copolymers, and cellulose phosphate (salt) in which the 1- and/or 4-position hydroxyl groups are inactivated, as described in the 4901 specification. ), phosphate ester (salt) of 2-hydroxyethyl (meth)acrylic ester polymer or copolymer, phosphate ester (salt) of 2-hydroxypropyl (meth)acrylic ester polymer or copolymer, Polyacrylic acid (salt), polymethacrylic acid (salt),
polystyrene sulfonate), polyvinyl alcohol sulfate, polyglutamic acid salt), alginic acid (
salts), carboxymethyl cellulose, 2-acrylamide-2-methylpropanesulfonic acid polymers (salts) or copolymers (salts), among which phosphoric acid esters of polyhydroxy compounds or salts thereof are particularly preferred. .

The water-soluble cationic polymer used in the treatment liquid of the present invention is preferably a water-soluble compound having a molecular weight of about 5oo-too:o6o. Specifically, aniline resin hydrochloride, polythiourea hydrochloride, cationized amino resin, polyvinylpyridine hydrochloride, cationically modified polyacrylamide (vinyl amide/polymer obtained by Hofmann decomposition of polyacrylamide, polyacrylamide mixed with formalin and secondary amine) polyvinylbenzyl chloride subjected to Mannich reaction with tertiary amine, polyvinylbenzyl chloride converted into quaternary ammonium salt with tertiary amine,
N vinyl-2=methylimidazolium methylsulfate), dimethylaminoethyl (meth)acrylate polymer and its quaternary ammonium group, amino group-containing (meth)acrylate polymer (diethylaminoethyl (meth)acrylate polymer and its quaternary ammonium salt)
, a polyalkylimine in which part or all of the amine groups of a polymer containing an aliphatic amino group in the repeating unit are changed into a salt or a quaternary ammonium salt, as described in Japanese Patent Publication No. 45-24609. Examples include, but are not limited to, compounds, or quaternary ammonium salts such as amine adducts of epoxy resins, amine adducts of maleated polymers, amino group-containing polyamide resins, polyamide epoxy resins, and boria middle epichlorohydrin resins. isn't it.

Furthermore, the solubility in water used in the treatment liquid of the present invention is 1.
The electrolyte compound containing 0% by weight or more is an alkali metal salt, alkaline earth metal salt, ammonium salt or amine salt of formic acid, oxalic acid, sulfuric acid, nitric acid, sulfamic acid or carbonic acid.

Specifically, A...? NO3, Ba(NO3)z, Ba(
SOaNHz )2, Ca(No++)z, Ca(SO
aNHz) 2. KHCO3, KH-3O4, KN
O3, K2SO4, LiNO3, MgCo3, M#S
O4, NHs No a, (NH4)2SO4, NH4
'503NH2, NazCO:+, NaNO3, Na5
O3NH2, HCOONa.

HCOOKSNaOOCCOONa, KOOCCOO
Examples include Na, guanidine carbonate, and ammonium carbonate. In addition, reducing salts such as nitrites and sulfites are also included if they are oxidized and turn into nitrates or sulfates. The solubility of these electrolyte compounds in water is 10% by weight or less! l! If it is made into a liquid, it will form crystals if left for a long time, which is undesirable. Preferably the solubility in water is 20
% by weight or more.

The present invention has discovered a processing solution with a high etching speed by adding an electrolyte compound consisting of a salt of a specific acid to an ionic complex of an anionic compound and a cationic compound. Even if a phosphoric acid salt is used in place of the electrolyte compound of the present invention, the enching speed is low and sufficient desensitizing power cannot be obtained. Also, NaCe%NH4Cl! Salts of halogenated acids such as KBr and KBr are highly corrosive to metals and are therefore unsuitable as the electrolyte compound of the present invention.

The amount of the above substances constituting the treatment solution of the present invention is 1 to 2 parts by weight of an anionic compound having the ability to form a chelate with zinc ions in 1000 parts by weight of the treatment agent, more preferably 4 parts by weight.
0 to 75 parts by weight, 20 to 150 parts by weight of electrolyte compound, more preferably 100 parts by weight of electrolyte compound, and 0.2 to 20 parts by weight of water-soluble cationic polymer, more preferably 1 to I
O parts by weight.

These compounds are dissolved in ion-exchanged water or tap water to prepare the main treatment liquid. Although the order of dissolution is not particularly limited, preferably, after dissolving zinc ions and an anionic compound having chelate-forming ability in water, the electrolyte compound is added, and then the cationic polymer aqueous solution is added. In addition to the above ingredients, the treatment solution also contains organic and inorganic acids, potassium hydroxide, basic hydroxides such as IJium hydroxide, etc. as pH adjusters.
Ethylene glycol, as a wetting agent! Sorbitol, glycerin, gum arabic surfactants, etc., preservatives such as salicylic acid, butyl phenol-parabenzoate, sodium dehydroacetate, 4-inthiazoline-
3-one compounds, etc., EDTA, amines, etc. as rust inhibitors.
It can be used by adding an appropriate amount.

When implementing the treatment liquid, it is preferable that the pH value of the treatment liquid is in the range of 3 to 6. It can also be used as a dampening solution by diluting it with water.

As described above, the treatment liquid of the present invention does not contain ferrocyan and ferricyanide compounds that cause pollution problems and deteriorate due to light and heat, is stable even under long-term storage, does not discolor or precipitate, and is similar to conventional cyanide-free treatment. It is an excellent cyan-free material that is not affected by the printing environment compared to liquids, has a significantly faster film formation rate, and can produce offset printing original plates that do not cause background smear or halftone gradation even during high-speed etching processing. It is a processing liquid.

The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 was sufficiently dissolved, and glycolic acid was added to adjust the pH to 4.5.

On the other hand, after forming an image on an electrophotographic photosensitive material containing a zinc oxide-resin dispersion system in a conventional manner, it was subjected to high-speed etching treatment with the above-mentioned processing solution to obtain an offset master original plate, and the above-mentioned processing solution was added to dampening water. Offset printing was performed using a solution diluted 5 times with water. The results are shown in Table-1.

Examples 2 to 9, Comparative Examples 1 to 7 Offset printing was performed in the same manner as in Example 1 using the compounds shown in Table 1 as electrolyte compounds. Display the results -
Shown in 1.

Table-1 Performance of cyanide-free processing liquid (25C-60%RH
) In Comparative Examples 5 to 7, a printing test was not conducted because precipitation occurred in the processing liquid.

As can be seen from Table 1, in Examples 1 to 9, even after high-speed etching, there was no scuffing on the master or prints after printing 4ρ00 sheets, the ink adhesion was good, and the prints were clear with no halftone gradations. In addition, there was no precipitate in the treatment agent itself, and no corrosion was observed on the aluminum plate.

Example 10 Glycolic acid was added to adjust the pH to 4.0.

An offset master printing plate was prepared by high-speed etching in the same manner as in Example 1, and printed using the treatment solution of Example 1 diluted 5 times with water as a dampening solution. A clean print was obtained.

Example 11 Glycolic acid was added to adjust the pH to 4.0.

An offset master printing plate was prepared by high-speed etching in the same manner as in Example 1, and printed using the treatment solution of Example 1 diluted 5 times with water as a dampening solution.
More than one page of prints without background stains were obtained.

patent applicant Tomoe Paper Mill Co., Ltd. Fuji Photo Film Co., Ltd. 539-

Claims (1)

[Scope of Claims] A desensitizing liquid for cyan-free offset printing, characterized by containing the following (a), (b) and (c) as active ingredients. (a): Anionic compound other than ammonium salt or amine salt of inositic hexaphosphate ester with a molecular weight of about 500 or more and capable of forming a chelate with zinc ions, (b): Water-soluble cationic polymer, (C): Formic acid, An electrolyte compound having a solubility in water at room temperature of at least one selected from alkali metal salts, alkaline earth metal salts, ammonium salts, and amine salts of acids, sulfuric acid, nitric acid, sulfamic acid, or carbonic acid of 10% by weight or more.