JPH0662020B2 - Lithographic printing plate desensitizing composition - Google Patents

Description

The present invention relates to a lithographic printing plate desensitizing composition. More specifically, the present invention is a composition for desensitizing treatment containing phytic acid or a functional derivative thereof as a main component, which enhances the desensitizing treatment effect by adding a dibasic acid or a metal salt thereof. The present invention relates to a desensitizing liquid composition useful for obtaining a lithographic printing original plate excellent in reproducibility of fine lines even when printing a large number of sheets by adding a divalent metal salt.

[Conventional technology]

An offset lithographic printing original plate using electrophotography as a basic principle of plate making comprises a sheet substrate and a photoconductive photosensitive layer formed on the sheet substrate and containing a photoconductive substance such as zinc oxide as a main component. A printing plate having a toner image can be manufactured by subjecting the original plate to a photosensitive treatment with a desired pattern and developing the photosensitive plate with an oil-sensitive developer.

As a method for producing another offset lithographic printing plate, a sheet-shaped substrate, and to form an original plate composed of an image receiving layer formed thereon, containing a binder and an inorganic pigment, on the receiving layer, A method of transferring an electrophotographic image created separately is also known.

As another method for producing an offset lithographic printing plate, a master plate having an image receiving layer is directly subjected to writing or type printing with an oil-based ink to obtain a printing plate, so-called offset image offset master (direct drawing master). The manufacturing method is also known.

When offset lithographic printing is performed using the printing plate as described above, it is necessary to apply a desensitizing treatment to this portion in order to make the non-image portion on the plate surface hydrophilic. In particular, when a lithographic printing original plate having a photoconductive photosensitive layer is used, the non-image portion, which should originally be hydrophilic, also shows a considerable lipophilicity, so it is important to subject this portion to a desensitizing treatment.
If this treatment is insufficient, stains are likely to occur on the non-image portion during printing, and particularly when printing is continued for a long period of time, it is impossible to stably obtain a clear printed matter without background stain.

At present, as this desensitizing treatment liquid, that is, the etching liquid,
The following are known when roughly classified.

(1) Those containing an organic acid, an inorganic acid and salts thereof as a main component. (For example, Japanese Examined Patent Publication No. 43-28404) (2) Those containing ferrocyan salt or ferricyan salt as a main component. (For example, Japanese Examined Patent Publication No. 39-8416) (3) Using phytic acid (Japanese Examined Patent Publication No. 45-24609) However, the above-mentioned known desensitizing solution (1) has a low desensitizing effect, and In addition, the background stain is remarkable on the printed matter during printing, and it is difficult to stably obtain a clear printed matter for a long period of time.

Further, the known desensitizing treatment liquid (2) has a considerably higher desensitizing effect than the known desensitizing treatment liquid (1), but the effect itself is not always sufficient. However, it has the drawback of being unstable to light and heat, and for this reason printing of neutral paper that generates a lot of paper dust,
Alternatively, when the printing pressure is high at the time of printing, there is a problem that print stains are likely to occur on the printed matter.

In view of the above problems, a processing solution using a natural product, that is, a desensitizing processing solution (3) using phytic acid has been proposed in consideration of work stability.

However, the known desensitizing treatment liquid (3) has an extremely low chelating power, and therefore its desensitizing effect was not practical.

[Problems to be solved by the invention]

The present invention, the main component of the desensitizing treatment liquid is phytic acid,
It is intended to provide a lithographic printing desensitizing composition which is stable to heat and light, has a practically sufficient desensitizing effect, and has little or no toxicity to the human body.

[Means for solving problems]

The above problems are solved by the present invention. That is, the lithographic printing desensitizing treatment composition of the present invention comprises components (A), (B) and (C) (A) phytic acid, or monovalent or divalent phytic acid, each of which comprises the following compounds. A water-soluble salt of a valent metal, (B) a dibasic acid or a metal salt thereof, and (C) a compound of the following general formula (I) or a hydrate thereof: MXl (I) [wherein Represents a divalent metal atom, X represents a monovalent or divalent anion, and 1 represents an integer of 1 or 2] as an active ingredient.

In the present invention, phytic acid used for a known desensitizing treatment has an inadequate desensitizing effect but its safety is noted, and earnest studies have been conducted on its use. As a result, phytic acid, due to its low desensitizing effect, breaks down the technical common sense of the industry that it cannot be used for practical desensitizing treatment liquids, and has a strong desensitizing power,
A lithographic printing plate desensitizing composition that can form a strong hydrophilic coating rapidly, does not reduce its desensitizing power even when exposed to heat or water, and is safe for the human body. It's a successful acquisition.

In the composition of the present invention, the components (A), (B),
When (C) is used alone, it exhibits almost no ability to desensitize and hydrophilize the printing original plate. Among these components, the composition obtained by blending the components (A) and (B) exhibits excellent desensitization, and a clear printed matter can be obtained. However, there is a problem that the thin line in the image area disappears as it progresses, that is, the so-called plate jump phenomenon occurs with a relatively small number of printed sheets, and the printing durability is low. However, the composition of the present invention obtained by adding the component (C) to these and blending these components (A), (B), and (C) exhibits an excellent desensitizing effect, and is not a non-image on the printing plate. It is possible to quickly form a tough hydrophilic coating on the line portion and suppress the occurrence of plate overprint in the image area. Therefore, by using the composition of the present invention, the printability and printing durability of the planographic printing plate can be greatly improved.

In the composition of the present invention, the component (A) is phytic acid,
Alternatively, the functional derivative of phytic acid is a water-soluble salt of a monovalent or divalent metal of phytic acid, such as sodium phytate, potassium phytate, and calcium phytate. You can choose from tate, etc.

It is known that these phytic acids or derivatives thereof form chelate compounds with metals.

For example, phytic acid or its derivative can form a chelate bond with a metal oxide (ZnO, TiO ₂ , CaO, etc.). However, even if these compounds are used alone as a processing solution for lithographic printing, the printing plate can hardly be desensitized.

The desensitizing treatment liquid mainly composed of phytic acid is a electrophotographic offset printing original plate having a photosensitive layer containing, for example, a photoconductive substance when it is attached to the plate surface and containing this zinc oxide and a resin binder ( (Hereinafter referred to as "zinc oxide master"), zinc oxide on the plate surface becomes Zn ions and dissolves into the treatment liquid, and then 4 to 6 per 1 mol of phytic acid.
After the moles of Zn ions have reacted, the formed chelate compound first deposits on the plate surface, which contributes to the hydrophilicity of the plate surface. Therefore, the above-described two-step process is required to form the hydrophilic film, and thus the conventional desensitizing treatment solution mainly containing phytic acid is a treatment solution using the above-mentioned ferrocyanine compound or ferricyanide compound. In comparison, the hydrophilization rate was slower, and therefore it could not exist in the market as a practical processing solution.

In order to solve the above-mentioned drawback of phytic acid or a derivative thereof being hydrophilized at a low speed, the present inventors have earnestly studied, and as a result, by using phytic acid and a dibasic acid together, its principle is not exactly known. However, it has been found that the rate of hydrophilization is remarkably improved by the effect presumed to promote the chelate reaction in some form. Japanese Patent Application Laid-Open No. 62-77994 shows a similar effect of phytic acid and dibasic acid. However, although the hydrophilic treatment speed could be improved, as it was, there was a problem that the plate jump was generated earlier with the improvement of the hydrophilic speed. Therefore, as a result of further research, the problem of plate jumps can be solved by adding a divalent metal, and the present invention has been achieved.

In the composition of the present invention, the desensitizing treatment with the component (A) is performed at a high speed by using the component (A) in combination with the components (B) and (C). It has succeeded in forming a toe and making it difficult for printing to occur.

Examples of the dibasic acid used as the component (B) in the composition of the present invention include maleic acid, oxalic acid, malonic acid, phthalic acid, itaconic acid, citraconic acid, succinic acid, fumaric acid, isophthalic acid, terephthalic acid, Dartalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, eltimalonic acid, diethylmalonic acid, dimethylmalonic acid, di-n-propylmalonic acid, isopropylmalonic acid, methylmalonic acid, propylmalonic acid, nona Methylenedicarboxylic acid, decamethylenedicarboxylic acid, undecamethylenedicarboxylic acid, dodecamethylenedicarboxylic acid, tridecamethylenedicarboxylic acid, tetradecamethylenedicarboxylic acid pentadecadicarboxylic acid, hexadecamethylenedicarboxylic acid, heptadecamethylenedicarboxylic acid, octadeca Methylene dicarboxylic , Nona decamethylene dicarboxylic acid,
Examples thereof include eicosamethylenedicarboxylic acid, heneicosamethylenedicarboxylic acid, docosamethylenedicarboxylic acid, tetracosamethylenedicarboxylic acid, ocotacosamethylenedicarboxylic acid, dotriacontaylenedicarboxylic acid and their derivatives, and metal salts. Further, these dibasic acids can be used in combination of two or more kinds.

The component (C) in the composition of the present invention has the following general formula: MXl (I) [wherein M is a divalent metal atom, X is a monovalent or divalent anion, and l is 1]. Or an integer of 2] or a hydrate thereof. In the general formula (I), the divalent metal atom represented by M is preferably nickel, manganese, magnesium,
It is selected from atoms such as cobalt, copper (II) and calcium. The anion represented by X is preferably sulfate ion, acetate ion, halogen ion (chlorine ion,
Bromine ion, iodine ion) citrate ion, monohydrogen phosphate ion, dihydrogen phosphate ion, and the like. The valence of l is such that when X represents a monovalent anion,
2 and 1 when X represents a divalent anion.

Examples of the metal compound of the general formula (I) used as the component (C) include nickel sulfate, nickel acetate, nickel chloride, nickel bromide, nickel iodide, nickel citrate, manganese sulfate, manganese acetate, manganese chloride, and bromide. Manganese, manganese iodide, manganese citrate, magnesium sulfate, magnesium acetate, magnesium chloride, magnesium bromide, magnesium iodide, cobalt sulfate, cobalt acetate, cobalt chloride, cobalt bromide, cobalt iodide, copper sulfate, copper acetate, It can be selected from copper (II) chloride, copper (II) bromide, calcium acetate, calcium dihydrogen phosphate, calcium chloride, calcium bromide and calcium iodide.

In the composition of the present invention, the components (A), (B),
The content of (C) can be arbitrarily set as desired as long as the object of the present invention is achieved. Generally, in 100 parts by weight of the composition of the present invention, the component (A) is preferably 0.
4 to 20 parts by weight is included, and the component (C) is preferably 1 to 10 mol, more preferably 4 to 10 mol, relative to 1 mol of the component (A).
The amount of the component (B) is 0.1 to 20 parts by weight.

In addition to the above, the composition of the present invention may further contain a water-soluble polymer such as polyacrylic acid, modified polyacrylic acid, polyacrylic acid copolymer and a metal salt thereof, polyethylene glycol, polyvinyl alcohol, or carboxymethyl cellulose. , An ethylene glycol or diethylene glycol derivative, an organic solvent such as a ketone or an alcohol, an organic acid such as citric acid can be used, and furthermore, a preservative such as sodium tetrahydroacetate salicylic acid and a surfactant as a wetting agent can be used. Can be added.

[Work]

In the composition of the present invention, the component (A), the component (B),
By combining (C), the desensitizing treatment of a lithographic printing plate, especially a lithographic printing plate having a zinc oxide-containing photosensitive layer, can be carried out quickly and effectively, and a strong hydrophilic film is formed. I was able to make it harder to get a print jump. As a result, it is possible to perform printing with excellent printing durability in which there is no stain on the printing background and there is no overhang on the plate in the image area.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 Phytic acid 5 parts Malonic acid 1 part Copper sulfamate (40%) 10 parts Ethylene glycol 2 parts Monoethyl ether water 82 parts A liquid composition obtained by mixing with 20% KOH aqueous solution to pH 3.5. It was adjusted and used as a desensitizing solution.

Example 2 Phytic acid 8 parts Malonic acid 1 part Succinic acid 3 parts Magnesium chloride hexahydrate 3 parts Ethylene glycol 3 parts Monophenyl ether water 82 parts A composition obtained by mixing with 20% aqueous NaOH solution
The desensitizing solution was adjusted to 3.2.

Example 3 Monopotassium phytate 8 parts Sodium oxalate 3 parts Cobalt chloride / anhydrous 2 parts Ethylene glycol 5 parts Monoethyl ether acetate Water 82 parts A composition obtained by mixing is adjusted to pH 3.1 for desensitization. It was used as a treatment liquid.

Example 4 Phytic acid 8 parts Maleic acid 2 parts Calcium sulfate dihydrate 5 parts Diethylene glycol 3 parts Monomethyl ether water 82 parts The composition obtained by mixing was adjusted to pH 2.5 to prepare a desensitizing solution. .

Example 5 Phytic acid 7 parts Citraconic acid 1 part p-Toluenesulfonic acid 2 parts Nickel acetate tetrahydrate 6 parts Tripropylene glycol 5 parts Water 79 parts The resulting composition was adjusted to pH 3.8, The desensitizing solution was used.

Example 6 Phytic acid 5 parts Ethylmalonic acid 1 part Calcium bromide dihydrate 7 parts Diethylene glycol 3 parts Monoethyl ether water 84 parts The mixture obtained by mixing and stirring was adjusted to pH 3.9 to desensitize. It was used as a treatment liquid.

Comparative Example 1 Phytic acid 5 parts Malonic acid 1 part Ethylene glycol 2 parts Monoethyl ether water 92 parts A liquid composition obtained by mixing with 25% KOH aqueous solution
pH3. To prepare a desensitizing solution.

Comparative Example 2 Phytic acid 8 parts Succinic acid 3 parts Malonic acid 1 part Water 88 parts The composition obtained by mixing with 20% NaOH aqueous solution to pH
The desensitizing solution was adjusted to 3.2.

Comparative Example 3 A composition obtained by mixing monopotassium phytate 8 parts sodium oxalate 3 parts ethylene glycol 5 parts monoethyl ether acetate water 84 parts was adjusted to pH 3.1 to prepare a desensitizing solution.

Comparative Example 4 A composition obtained by mixing 8 parts of phytic acid with 2 parts of maleic acid and 90 parts of water was adjusted to pH 2.5 to prepare a desensitizing solution.

Comparative Example 5 Phytic acid 7 parts Citraconic acid 1 part p-Toluenesulfonic acid 2 parts Water 90 parts The composition obtained was adjusted to pH 3.8 and subjected to desensitization treatment.

Comparative Example 6 Phytic acid 5 parts Diethylene glycol 3 parts Monoethyl ether water 92 parts were mixed and the resulting composition was adjusted to pH 3.9 to obtain a desensitizing solution.

Comparative Example 7 Monopotassium Phytate 8 parts Cobalt Chloride / Anhydride 2 parts Ethylene Glycol Monoethyl 5 parts Ether Acetate Water 85 parts The composition obtained was adjusted to pH 3.1 to prepare a desensitizing solution. .

Example 7 and Comparative Example 8 Examples 1 to 6 and Comparative Example 1 were applied to commercially available zinc oxide / resin-dispersed electrophotographic photosensitive materials on which images were formed by an electrophotographic plate making machine.
The processing solution obtained in ~ 6 is applied to the photosensitive layer by the etching process by the automatic etching process (Ricoh etching processor) to make an offset printing plate, and the dampening water diluted with the processing solution 10 times is used. Then, offset printing was performed. The results are as shown in Table 1.

As shown in Table 1, using any of the desensitizing treatment liquids of Examples 1 to 6, printing of 5,000 sheets showed no stain on the printed matter,
In addition, clear printed matter was obtained without generation of plate jumps.

However, when the treatment liquids of Comparative Examples 1 to 7 lacking at least one of the components (B) and (C) were used, plate nibbles occurred relatively early in any of the Comparative Examples, and the resistance to 1,000 or more sheets was No printable product was obtained.

〔The invention's effect〕

With the composition of the present invention, desensitization treatment of a lithographic printing plate can be carried out quickly, safely, and effectively, and extremely high printing durability, a strong hydrophilic film is formed on the plate surface. However, it has become possible not only to prevent the printing ground from becoming dirty, but also to prevent plate jumps.

Claims (5)

[Claims] 1. A component (A) comprising the following compounds,
(B), (C): (A) Phytic acid, or a water-soluble salt of a monovalent or divalent metal of phytic acid, (B) a dibasic acid or a metal salt thereof, and (C) the following general formula Compound of (I) or hydrate thereof: MXl (I) [wherein M represents a divalent metal atom, X represents a monovalent or divalent anion, and l is 1 or 2] Represents an integer of], and a desensitizing composition for lithographic printing plate containing as an active ingredient. 2. The composition according to claim 1, wherein the water-soluble salt of a monovalent or divalent metal of phytic acid is selected from sodium phytate, potassium phytate and calcium phytate. 3. The divalent metal atom represented by M in the general formula (I) is selected from Ni, Cu (II), Mg, Co, Ca, and Mn. Composition. 4. In the general formula (I), the anion represented by X is selected from sulfate ion, acetate ion, monohydrogen phosphate ion, dihydrogen phosphate ion, citrate ion, and halogen ion. Claims No. 1
The composition according to the item. 5. The content of the component (A) is 0.4 to 20 parts by weight, the content of the component (C) is 1 to 10 mol per 1 mol of the component (A), and The composition according to claim 1, wherein the content of the component (B) is 0.1 to 20 parts by weight.