JP3172285B2 - Humidifying liquid composition for lithographic printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate surface treating solution composition for a lithographic printing plate, and more particularly to a humidifying solution.

[0002]

2. Description of the Related Art In lithographic printing, both water and ink are supplied to a printing plate, an image portion selectively receives color ink, and a non-image portion selectively receives water, and the ink on the image, for example, paper. It is made by transferring it to the like. Therefore, in order to obtain good printed matter, the difference between the lipophilicity and hydrophilicity of the surface between the image area and the background non-image area is sufficiently large, and when water and ink are applied, the image area requires a sufficient amount of ink. It is necessary that the receiving and non-image parts do not receive any ink. For this purpose, various desensitizing methods are used according to the respective plate materials and printing methods. That is,
Conventionally, lithographic printing materials include presensitized plates (PS plates) using a metal such as aluminum as a support, plate materials obtained by electrophotography (eg, electrofax), and paper. There is a so-called master paper in which a pigment is coated with a binder on the surface of the base plate, and a photoengraving agent using a silver salt such as Japanese Patent Publication No. 48-30562. Plate making and printing processing methods for wet liquid and the like have been studied and embodied. Photographic materials made of silver halide having high sensitivity and spectral sensitization are suitable for automatic plate making of printing and have already been used in several forms.

A method in which a hydrophilic gelatin / silver halide emulsion is hardened by a method utilizing tanning development to harden the gelatin in the tanning development section to make it lipophilic and ink-receptive. (U.S. Pat. No. 3,146,104).

A printing plate (US Pat. No. 3,721,559, JP-B-48-30562, Journal of Photographic Sciences 8-2632) which utilizes a silver diffusion transfer method to lipophilize the formed surface metallic silver pattern and use it as ink acceptability. (1960) A. Rot
t. & L.Dehoes).

By applying an etching bleach, a developed silver image portion or a silver image portion formed by transfer development is treated with a bleaching solution, and at the same time, the gelatin in the silver pattern portion is destroyed to expose the lipophilic surface. To prepare a lithographic printing plate (US Pat. Nos. 3,385,701, 3,099,209,
JP-A-53-9603).

A method of selectively accepting undeveloped silver halide image portions of a developed lipophilic gelatin-silver halide emulsion layer (US Pat. Nos. 3,454,398 and 3,454).
No. 099,209, JP-A-53-9603) and the like are typical methods of lithographic printing plates to which a photosensitive silver halide emulsion is applied.

[0007] In any lithographic printing plate, further improvement of printing characteristics such as ink receptivity, stain prevention and printing durability is desired, and image silver or silver halide formed by the above-mentioned photographic method is required. There is no exception in a lithographic printing plate utilizing as ink receptivity.

It is well known that fine particles having an average particle diameter of 0.1 μm or less, such as colloidal silica, are used in various plate surface treatment solutions subsequent to the development processing of such a silver salt printing plate. For example, the humidifying liquid of JP-A-48-45305, JP-A-54-835
Plate surface treatment liquids such as the neutralizing liquid of No. 02, the neutralizing liquid of JP-A-57-29046, the desensitizing liquid, the humidifying liquid, the fixing agent (liquid) of JP-B-45-29001, and the humidifying liquid.

However, generally, inorganic fine particles such as colloidal silica and colloidal alumina are sufficiently effective in preventing the printing background stain of a silver salt printing plate, but are inferior to PS plates embodied using a photosensitive resin. It has been found that this causes problems such as unevenness in the image area and a decrease in image density during printing. . In particular, when the particle size is 10 nm or less, such a tendency is noticeable. In addition, the stability of the fine particles is strongly dependent on the pH and the electrolyte concentration. For pH, precipitation occurs when the pH is adjusted to 5-6 due to the humidification solution, and gelation occurs when the pH is 8 or more. It has significant drawbacks.
In addition, the electrolyte is, for example, a compound containing Na, K, Ca, Mg, etc.
If it is added to these treatment solutions for adjustment or for controlling the conductivity, gelling and precipitation will occur.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly effective reproducible printing plate for both silver halide printing plates and PS plates with good reproducibility against changes in the composition, storage and manufacturing conditions of the printing plate. Another object of the present invention is to provide a lithographic printing plate surface treatment liquid capable of preventing background contamination without using inorganic fine particles and capable of printing a large number of good prints having a high ink concentration.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to provide a humidifying liquid for lithographic printing containing a nonionic surfactant comprising a block polymer represented by the following general formula: The present invention has been attained by the above composition comprising the above water-soluble vinyl polymer and polysaccharide, and substantially containing no inorganic fine particles of 0.1 μm or less.

[0012]

Embedded image

( M and n are the degree of polymerization required to make the average molecular weight of the block polymer 250 or more, and necessary for m / (m + n) to be 0.50-1.00. High degree of polymerization .)

The nonionic surfactants used in the moisturizing liquid composition of the present invention are described in JP-A Nos. 64-38292, 64-38293 and 64-38293.
Which has a propylene oxide group (hereinafter abbreviated as po) unit and an ethylene oxide group (hereinafter abbreviated as eo) unit as described in 64-82992,
It has a molecular weight of 250 or more, preferably 500-1000. The upper limit of the molecular weight is generally 5000, but may be higher.

The amount of the above-mentioned nonionic surfactant used is as follows:
The working solution is in the range of 2.5 to 10 g per liter.
The nonionic surfactant used in the present invention is known and can be obtained as a commercial product.

The water-soluble vinyl polymer used in the present invention includes polyvinyl alcohol, polyacrylic acid and its salts, polyvinylpyrrolidone, polyvinyl acetic acid and its salts, polymethacrylic acid and its salts, polyvinyl phosphoric acid and its salts, polyvinylbenzene sulfone. Examples thereof include acids and salts thereof, polyacrylamide, and polyallylamine, and may be either a homopolymer or a copolymer thereof.

The polysaccharide used in the present invention includes cellulose derivatives such as cellulose and methylcellulose, gum arabic, alginic acid, starch and the like, which are known and commercially available, and gum arabic is preferred.

The water-soluble vinyl polymer and the polysaccharide are preferably contained in an amount of 2 to 10% by weight based on the weight of the nonionic surfactant. It is preferable to contain 1 to 1.5 times the amount.

The term "substantially free of inorganic fine particles" as used in the present invention means that the ink density is reduced with respect to PS plate printing,
It means that it is not contained more than the amount that does not adversely affect the destruction of the resin image portion. More specifically, the solid content of the inorganic fine particles in the working liquid should not be more than 0.075 g.

The treatment activity can be modified by mixing conventionally known substances such as a desensitizing accelerator, a buffer, a preservative, and a wetting agent into the moisturizing liquid composition of the present invention. .
For example, sulfates (sodium sulfate, ammonium sulfate, etc.), phosphoric acid, nitric acid, nitrous acid, tannic acid and salts thereof, and polyol compounds having two or more hydroxyl groups (polyethylene glycol, ethylene glycol, propylene glycol, glycerol, diethylene glycol, Hexylene glycol, etc.), organic weak acids (citric acid, succinic acid, tartaric acid, adipic acid, ascorbic acid,
Polyacrylic acid, such as propionic acid, ammonium bichromate, chromium alum, and aminopolycarboxylates (such as sodium ethylenediaminetetraacetate).

In addition, a small amount of a coloring agent such as a phthalocyanine dye, malachite green, or ultramarine can be added to the water-miscible organic solvent such as methanol, dimethylformamide, dioxane, or the like, particularly considering the distinguishability and appearance of the liquid. .

Hereinafter, the present invention will be described with reference to Examples.
Of course, it is not limited to this.

[0023]

【Example】

 Example 1

A moisturizing solution having the composition shown in the following table was prepared, and the liquid stability, silver salt printing plate printability and PS plate printability of each were evaluated.

[0025]

[Table 1]

The colloidal silica used here is an alumina coated type having an average particle diameter of 3-6 nm. The combination of surfactant / vinyl polymer / polysaccharide was performed for the following cases.

No. Surfactant Vinyl polymer polysaccharide 1 A polyacrylic acid arabic gum 2 A polyvinyl phosphate carboxymethyl cellulose 3 B polyacrylic acid carboxymethyl cellulose 4 B polyvinyl phosphate gum arabic

Surfactant A is represented by the formula:
/ N = 1/1, molecular weight 500, surfactant B
m / n = 1/1, molecular weight 1000.

The evaluation conditions of the liquid stability were 50 ° C. for one week and freeze-thaw was repeated three times, and thereafter the liquid state was visually observed. The printability evaluation conditions were: AB Dick 3500CD (trademark of offset printing machine manufactured by AB Dick Co., Ltd.) for the printing machine, F gloss navy blue (manufactured by Dainippon Ink), which easily caused background dirt on the printing ink. Using SLM-RII manufactured by Mitsubishi Paper Mills Co., Ltd. for the silver halide printing plate and FNS (negative type) FPS (positive type) manufactured by Fuji Photo Film Co., Ltd. for the PS plate, visually observe the dirt after printing 1,000 sheets. did.

The evaluation was performed according to the following criteria. Solution stability × Gelation or precipitation △ The whole solution becomes cloudy ○ No change to liquid Printability × Fully stained or reduced image density △ Partially stained or partially reduced image density ○ Printing without any problem

Table 2 shows the evaluation results.

[0032]

[Table 2]

[0033]

According to the present invention, the printability of the silver salt printing plate can be maintained without using inorganic fine particles, and the printability of the PS plate can be improved.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yoshida 3-4-2, Marunouchi, Chiyoda-ku, Tokyo Examiner at Mitsubishi Paper Mills Co., Ltd. Toshihiko Nakazawa (56) References JP-A-3-63188 (JP, A) JP-A-64-38293 (JP, A) JP-A-64-38292 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41N 3/08 101

Claims (1)

(57) [Claims] 1. A block polymer represented by the following general formula:
In a humidifying liquid for lithographic printing containing a nonionic surfactant consisting of at least one or more water-soluble vinyl polymers and polysaccharides, and substantially 0.1 μm or less of inorganic fine particles. A moisturizing liquid composition characterized by not containing. Embedded image (M and n are an average molecular weight of the block polymer of 250
The degree of polymerization required to achieve the above, and m / (m +
n) represents the degree of polymerization required for 0.50-1.00 . )