JPH0517878B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Field of Application> The present invention relates to an electrophotographic offset printing plate surface treatment liquid, and more particularly to a desensitization treatment liquid for cyan-free offset printing that does not contain any cyan compounds. <Prior art> An electrophotographic offset printing original plate (hereinafter referred to as a master) has a photosensitive layer in which photoconductive fine powder such as zinc oxide is dispersed in a resin binder, and a conventional electronic printing plate is formed on this layer. Obtained by photographic manipulation 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), but electrophotographic offset printing original plates are Since the image area 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. Conventionally, this type of desensitizing treatment liquid includes ferrocyanate, a cyanide compound-containing treatment liquid containing ferricyanide as a main component, and a cyanide-free treatment liquid containing ammine cobalt base, phytic acid and its derivatives, and guanidine derivatives as main components. has been raised. However, these processing solutions cannot be said to be fully satisfactory processing solutions. That is, in the case of the former ferrocyan salt and ferricyan salt-containing treatment solution, the desensitizing power is strong and the ability to form a strong hydrophilic film is strong.
Although it has the advantage of fast film formation speed, on the other hand, ferrocyan ions and ferricyan ions are thermally unstable to light and become colored and precipitate when exposed to light, weakening their desensitizing power. ), which is detected as free cyanide, which poses various problems in terms of pollution, such as drainage. On the other hand, in consideration of these points, cyan-free processing liquids containing a desensitizing agent as the main component have been proposed, but even with these, it is still not possible to obtain a sufficiently satisfactory lithographic printing original plate. I can't say that. Specifically, the film formation speed is slower than the former, and the etching method using a processor cannot form a hydrophilic film with high physical strength that can be immediately printed in one pass, resulting in background smudges and halftone gradation. It has the disadvantage of causing It is well known that inositohexalic acid esters and their metal derivatives form chelate compounds with metals, and various types of desensitizing agents for offset printing original plates have been provided. However, with these methods, the film formation speed is slow, and a hydrophilic film that can be printed is not formed in a single processing using a processor.As a result, ink separation is poor, causing background smearing and halftone gradation, and printing. It is easily influenced by the environment and has the disadvantage that under low humidity conditions, background smudges may occur even after the processor has been used twice. 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 inositohexalic acid ester and water-soluble cationic polymers were used. A complex method was proposed, but although this improved water retention, it had the disadvantage that a satisfactory etching speed could not be obtained. <Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned circumstances. The present invention provides a desensitizing treatment liquid for free offset printing. <Means for solving the problems> The present invention provides: (a) phytic acid, phytic acid metal salt, phytic acid ammonium salt, phytic acid organic amine salt, 1
Inositohexalic acid ester derivatives, vinyl sulfonic acid (salt) polymers or copolymers, cellulose phosphate (salt), 2-hydroxyethyl (meth)acrylic acid, in which the hydroxyl group at position or 4-position is inactivated. Chelate with at least one zinc ion selected from phosphate esters (salts) of ester polymers or copolymers, phosphoric esters (salts) of 2-hydroxypropyl (meth)acrylic ester polymers or copolymers. Anionic compound with the ability to form. (b) Cationic surfactants (c) Formic acid, oxalic acid, sulfuric acid, nitric acid, sulfamic acid,
Cyanide-free offset consisting of at least one electrolyte compound selected from alkali metal salts, alkaline earth metal salts, ammonium salts, or organic amine salts of phosphoric acid, polyphosphoric acid, or carbonic acid and having a solubility in water of 10% or more at room temperature. This is a desensitizing liquid for printing. The water-soluble anionic compound having the ability to form a chelate with zinc ions used in the treatment solution of the present invention includes:
JP-A-57-199694, JP-B-45-24609, JP-A-51-103501 and JP-A-54-
Phytic acid or its metal salt as described in Japanese Patent Application No. 10003, ammonium salt or organic amine salt of phytic acid as described in Japanese Patent Application No. 58-130348, Japanese Patent Application No. 83806-1986, 1978
-83807 specification, JP-A-53-109701 specification 3
Inosite in which the hydroxyl group at the 1st or 4th position is inactivated, as described in JP-A-53-127002, JP-A-53-127003, and JP-A-54-44901 Hexaphosphate derivative, vinylphosphonic acid (salt) polymer or copolymer, cellulose phosphate (salt), 2-hydroxyethyl (meth)
Phosphate ester (salt) of acrylic ester polymer or copolymer, 2-hydroxypropyl (meth)
Examples include phosphoric acid esters (salts) of acrylic acid ester polymers or copolymers. Specifically, the cationic surfactants used in the treatment liquid of the present invention include RN (CH ₃ ) ₃ Cl (where R is an alkyl group having 5 or more carbon atoms),

[Formula] (where R is an alkyl group having 3 or more carbon atoms),

[Formula] (where R is an alkyl group having 3 or more carbon atoms),

[Formula] (where R is an alkyl group having 5 or more carbon atoms), C ₁₁ H ₂₃ CONH(CH ₂ ) ₃ N
_{( CH3} ) _{2COOC2H5 ・}Cl, and so on. Among them, benzyl-type quaternary ammonium salts having a benzene ring in the molecule and having a molecular weight of about 100 to 1000 are preferred. Further, examples of organic or inorganic electrolytic compounds having a solubility in water of 10% or more used in the treatment solution of the present invention include formic acid, oxalic acid, sulfuric acid, nitric acid, sulfamic acid,
Examples include alkali metal salts, alkaline earth metal salts, ammonium salts, or organic amine salts of phosphoric acid, polyphosphoric acid, or carbonic acid. Specifically, AgNO ₃ , Ba
( _NO3 ) ₂ , Ba( _SO3NH2 ) _, Ca( _NO3 ) ₂ , Ca
( _SO3NH2 ) _{2 , KHCO3} , _KHSO4 , _KNO3 ,
_LiNO3 , _MgCO3 , _MgSO4 , _{NH4CO3 ,}
(NH ₄ ) ₂ SO ₄ , NH ₄ SO ₃ NH ₂ , NaCO ₃ , NANO ₃ ,
_NaSO3NH2 , _HCOONa , HCOOK,
Examples include NaOOCCOONa, KOOCCOONa, guanidine carbonate, and ammonium carbonate. In addition, reducing salts such as nitrites and sulfites are also included if they are oxidized and converted to nitrates or sulfates. If the solubility of these electrolyte compounds in water is less than 10% by weight, crystals will form if left for a long period of time when used as a treatment solution, which is undesirable. Preferably, the solubility in water is 20% by weight or more. The present invention provides 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 surfactant. The amount of the above substances constituting the treatment solution of the present invention is such that the amount of the water-soluble anion compound having the ability to form a chelate with zinc ions is 10 to 1000 parts by weight of the treatment solution.
200 parts by weight, more preferably 40 to 75 parts by weight, and 20 to 150 parts by weight of electrolyte compound, more preferably 40 to 75 parts by weight.
100 parts by weight and 0.2 to 20 parts by weight of the cationic surfactant, more preferably 1 to 10 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 a water-soluble anionic compound having chelate-forming ability in water, the electrolyte compound is added, and then the cationic surfactant is added. In addition to the above ingredients, the treatment solution contains formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, oxalic acid, malonic acid, succinic acid, glutamic acid, and maleic acid as PH adjusters and anti-settling agents. , fumaric acid, citraconic acid, itaconic acid, tricarballylic acid, propane-1.1.2.3.-tetracarboxylic acid, butane-1.2.3.4.-tetracarboxylic acid, glycolic acid, thioglycolic acid, lactic acid, β-hydroxypropionic acid , malic acid, citric acid, gluconic acid, pyruvic acid, diglycolic acid, thioglycolic acid, mercaptosuccinic acid, salicylic acid, tyron, pyridine-2,3-dicarboxylic acid, iminodiacetic acid, hydroxyethyliminodiacetic acid, phosphonomethylimino Diacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminetetrapropionic acid, cyclohexane
1.2-diaminetetraacetic acid, diethylenetriaminepentaacetic acid, glycol ether diaminetetraacetic acid, trimethylenetetraaminehexaacetic acid,
Glycine, sarcosine, β-alanine, α-aminobutyric acid, aspartic acid, glutamic acid, phosphoric acid, pyrophosphoric acid, hexametaphosphoric acid, polyphosphoric acid, aromatic sulfonic acids (e.g. toluenesulfonic acid, benzenesulfonic acid, t-butylnaphthalenesulfonic acid) , dodecyl diphenyl ether disulfonic acid, etc., acids and their salts, wetting agents such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, phenyl glycol, propylene glycol, sorbitol, glycerin, gum arabic, etc., preservatives such as salicylic acid, Butyl phenol parabenzoate, sodium dehydroacetate, 4-isothiazoline-3-ion compound, etc., and other additives such as water-soluble dyes, colloidal silica, amines, etc. can be added in appropriate amounts.Execute the treatment solution. In this case, 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. Example 1 Water 1000 parts by weight Ammonium phytate salt (50% aqueous solution)
100 〃 (NH ₄ ) ₂ SO ₄ 80 〃

[Formula] 10 〃 Salicylic acid 1 〃 Glycerin 200 〃 Add ammonia water and adjust to PH4.2. Example 2 Water 1000 parts by weight Magnesium phytate (50% aqueous solution)
100 〃 K ₂ SO ₄ 50 〃

[Formula] 5 〃 Diethylenetriaminepentaacetic acid 10 〃 Ethylene glycol 100 〃 Sodium dehydroacetate 1 〃 Add ammonia water and adjust the pH to 4.2. Example 3 Water 1000 parts by weight Polyvinyl alcohol sulfate ester
100 〃 NH ₄ SO ₃ NH ₂ 50 〃

[Formula] 5 〃 Butyl phenol parabenzoate 0.5 〃 Sodium polyacrylate 100 〃 Add glycolic acid and adjust the pH to 4.5. Example 4 Water 1000 parts by weight Vinylphosphonic acid polymer (40% aqueous solution)
100 〃 HCOONa 60 〃

[Formula] 5 〃 1,2-Benzisothiazolone-3-one
0.5 〃 Glycerin 100 〃 Add phosphoric acid and adjust to PH4.5. Comparative example 1 Water 1000 parts by weight Ammonium phytate (50% aqueous solution)
100 〃 (NH ₄ ) ₂ SO ₄ 80 〃 Salicylic acid 1 〃 Glycerin 200 〃 Add phosphoric acid and adjust to PH4.20. Comparative Example 2 Water 1000 parts by weight Magnesium phytate (50% aqueous solution)
100 〃 K ₂ SO ₄ 50 〃 C ₈ H ₁₇ SO ₃ Na 10 〃 Glycerin 200 〃 Add ammonia water and adjust to PH4.5. Comparative Example 3 Water 1000 〃 2-Hydroxymethacrylic acid ester polymer (40% aqueous solution) 100 〃 NH ₄ NO ₃ 80 〃 C ₁₈ H ₁₇ N (CH ₃ ) ₂ CH ₂ COO 7 〃 Toluenesulfonic acid 10 〃 Glycerin 100 Weight part: Add NaOH and adjust to PH4.5. Zinc oxide to resin dispersion electrophotographic materials,
After image formation according to a conventional method, each was subjected to high-speed etching treatment using the above-mentioned processing liquids to prepare an offset original plate, and printing was carried out using a dampening solution diluted 5 times with water. The results are shown in the table below.

[Table] As can be seen from the table, the processing solutions of the present invention shown in Examples 1 to 4 have a fast film formation rate, so even with high-speed etching, more than 10,000 sheets can be printed without background smearing and ink adhesion. The quality was also good, and clear images with no halftone blockiness were obtained. However, Comparative Example 1 does not contain a cationic substance, and Comparative Examples 2 to 3 use an anionic activator and a zwitterionic activator.
Scratching occurred from the first sheet, and the ink separation was poor, making printing impossible. <Effects of the Invention> As explained above, the desensitizing treatment liquid for offset printing of the present invention does not contain ferrocyan or ferricyanide compounds, which have inherent pollution problems, and the film formation rate has been significantly improved. It has also become possible to perform excellent offset printing without background smudges or halftone gradations.

Claims (1)

[Scope of Claims] 1. A desensitizing liquid for cyan-free offset printing, characterized by containing the following (a), (b) and (c) as active ingredients. (a) Phytic acid, phytic acid metal salt, phytic acid ammonium salt, phytic acid organic amine salt, 1
Inositohexalic acid ester derivatives, vinyl sulfonic acid (salt) polymers or copolymers, cellulose phosphate (salt), 2-hydroxyethyl (meth)acrylic acid, in which the hydroxyl group at position or 4-position is inactivated. Chelate with at least one zinc ion selected from phosphate esters (salts) of ester polymers or copolymers, phosphoric esters (salts) of 2-hydroxypropyl (meth)acrylic ester polymers or copolymers. Anionic compound with the ability to form. (b) Cationic surfactants (c) Formic acid, oxalic acid, sulfuric acid, nitric acid, sulfamic acid,
An electrolyte compound of at least one selected from alkali metal salts, alkaline earth metal salts, ammonium salts, and organic amine salts of phosphoric acid, polyphosphoric acid, or carbonic acid and having a solubility in water of 10% or more at room temperature.