JPH06219076A - Dampening liquid composition for lithographic printing plate - Google Patents

Abstract

(57) [Summary] [Object] To provide a dampening liquid composition for a lithographic printing plate which exhibits excellent printability without using IPA. [Structure] Contain at least one nonionic surfactant represented by the following general formula [I], and
It was achieved by a dampening liquid composition for lithographic printing, characterized by containing a polymer represented by the formula I]. [Chemical 1] (R represents an alkyl group having 1 to 9 carbon atoms, and n ₁ and n ₂ are the number of moles required to make the average molecular weight of the block polymer 250 or more. N ₁ / n ₂ = 0.5-2 (2) (M is a number such that the molecular weight of the polymer corresponds to 2000-50000.)

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate surface treatment liquid composition for lithographic printing plates, and more particularly to a dampening liquid. More specifically, the present invention relates to a moisturizing liquid composition preferably used in a continuous water supply type moisturizing liquid device.

[0002]

2. Description of the Related Art In lithographic printing, both water and ink are supplied to a plate surface to selectively receive a coloring ink in an image area and water in a non-image area to absorb the ink on the image, for example, paper. It is made by transferring to. Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity on 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 non-image area accepts no ink. That is, it plays an important role in obtaining a printed matter having a proper ink / water balance.

If too much water, that is, a dampening liquid is supplied, the ink is excessively emulsified, which causes water loss and delays drying, which causes show-through. On the other hand, if the supply amount of the dampening liquid is too small, the ink adheres to the non-image area, which causes scumming.

The initial purpose of the dampening liquid is to prevent scumming that occurs during printing, and is prepared by the printing engineer himself using chromates and arabic gum and cellulose in combination. There were many things.

In a lithographic printing plate, a method of improving the ink / water balance has been considered in order to further improve the printing quality such as ink receptivity, stain prevention, speeding up and automation. Isopropyl alcohol (IPA) is generally added to the dampening liquid for this purpose, and the action of IPA is to increase the viscosity, decrease the surface tension, and form a proper W / O emulsion with the ink / humidifying liquid. is there.

Since the invention of the Dahlgren water supply system in the 1960s, every water supply system was designed from the beginning of development on the premise of using IPA. The characteristics of the continuous water supply apparatus are fully utilized by using IPA. That is, a uniform and minimum amount of dampening liquid can be supplied to the plate. The stabilization of water at the time of printing is fast, and the rising edge is reduced. In addition, recently, since water is squeezed and good printed matter can be obtained, it is also used in the Molton system and the sleep system.

However, with the recent revision of the Industrial Safety and Health Law, the organic solvent poisoning prevention regulations have been revised, and the IPA content of IPA aqueous solutions has been tightened to 5% or less, and the use of IPA has been prohibited overseas. There is. But I
When the PA content is 5% or less, good printed matter cannot be obtained, and the continuous water supply device developed for the purpose of coping with high speed cannot fully exhibit its true value. If it is used at 5% or more, it is necessary to install a local exhaust system.

Further, IPA is designated as a quaternary petroleum alcohol and is subject to regulation under the Fire Service Law. The Sewerage Act also requires adequate control of biochemical oxygen demand (BOD).

Another problem with using IPA is cost.
IPA for 4-sided off-wheels equipped with continuous water supply
The amount used is large, which is troublesome for printers.

In order to solve such problems of IPA, Japanese Patent Publication No. 61-55480 has devised a method for reducing alcohol. However, it is still insufficient regarding the organic solvent poisoning prevention regulations. Also, US Patent No. 38
77372, using butyl cellosolve, JP-A-57-19969, using 2-ethyl-1,3-hexanediol, and JP-A-58-176280, combining a glycol ether ester and a water-soluble polymer. . However, these dampening liquids have drawbacks such as stains on the water squeezing roller, entanglement of halftone images, and a narrow water width making it difficult to print. On the other hand, JP-A-3-923
In order to impart the printability equivalent to that of the IPA-containing dampening liquid to No. 92, it is possible to obtain a printability of at least 10 after the new surface is formed.
-Dynamic surface tension after ¹ second is 25-50mN / m (15 ℃)
It was stated that it was necessary to be within the range of 1.0 to 5.0 and the viscosity was within the range of 1.05 to 5.0 cp.

Although there have been various disclosures as the IPA alternative moisturizing liquid, there are many problems to be solved.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dampening liquid composition for a lithographic printing plate which exhibits excellent printability without using IPA.

[0012]

[Means for Solving the Problems] At least one nonionic surfactant represented by the following general formula [I] is contained, and a polymer represented by the general formula [II] is contained. It was achieved by a dampening liquid composition for lithographic printing.

[0013]

[Chemical 3] (R represents an alkyl group having 1 to 9 carbon atoms, n ₁ and n ₂ are the number of moles necessary for the average molecular weight of the block polymer to be 250 or more, and n ₁ / n ₂ = 0.5-2 It is.)

[Chemical 4] (M is a number such that the molecular weight of the polymer corresponds to 2000-50000.)

The nonionic surfactant used in the dampening liquid composition of the present invention comprises a hydrophilic portion having a propylene oxide group unit and an ethylene oxide group unit and a hydrophobic portion having an alkyl group having 1 to 9 carbon atoms. The molecular weight is 250 or more, preferably 500-3000. The upper limit of the molecular weight is generally 5000, but it may be higher.

The nonionic surfactant represented by the general formula [I] is known and can be obtained as a commercial product from NOF CORPORATION.

It is preferable that the nonionic surface active agent is contained in an amount of 1 to 10 g per liter of the liquid for use in the humidifying liquid.
It may be out of the above range. The nonionic surfactant efficiently exhibits a decrease in dynamic surface tension and an increase in viscosity at the above content.

The compound represented by the general formula [II] used in the present invention is a polycondensation product of vinyl phosphoric acid monomer and can be obtained as a commercial product. The degree of polymerization of the polymer is m = 3
5 to 75, 10 mg-10 per liter using the moisturizing liquid
It is preferable to contain 0 mg.

The dampening liquid composition of the present invention may be mixed with conventionally known substances such as a desensitizing agent, a buffer, a preservative and a wetting agent to modify the processing activity. . For example, gum arabic, carboxymethylcellulose, sodium alginate, polyvinylpyrrolidone, polyvinylimidazole, polyvinylphosphoric acid, sulfates (sodium sulfate, ammonium sulfate, etc.), phosphoric acid, nitric acid, tannic acid and salts thereof, and a polyol compound having two or more hydroxyl groups ( Polyethylene glycol, ethylene glycol, propylene glycol, diethylene glycol, etc.), weak organic acids (citric acid, succinic acid, tartaric acid, adipic acid, ascorbic acid, propionic acid, etc.), inorganic fine particles (alumina sol, colloidal silica, etc.), polyacrylic acid, Examples thereof include ammonium dichromate, chromium alum, aminopolycarboxylic acid salts (sodium ethylenediaminetetraacetate, etc.) and the like.

In addition to this, a trace amount of a colorant such as phthalocyanine dye, malachite green, and neal blue may be added in consideration of the water-miscible organic solvent such as methanol, dimethylformamide, dioxane or the appearance.

The dampening liquid composition of the present invention is particularly useful for a silver salt lithographic printing plate to which a silver halide emulsion is applied. However, it can also be used for other printing plates.

[0021]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Examples The following dampening liquid use liquids were prepared. Propionic acid 0.2 g Sodium nitrite 1.0 g Surfactant-free or 5 g Polymer 50 mg IPA-free or 200 g Prepared to 1 liter with water.

Surfactant Polymer IPA (R n ₁ = n ₂ ) (m = 55) 1 Comparative No No No Yes No 2 Invention n-butyl group 5 Yes No 3 Invention n-butyl group 9 Yes No 4 Invention n-butyl group 20 Yes No 5 Invention n-octyl group 5 Yes No 6 Invention n-octyl group 9 Yes No 7 Comparative n-butyl group 5 No No 8 Comparative n-butyl group 20 No No 9 Comparison No No No Yes 10 Comparison (ethyl cellosolve) No No 11 Comparison (ethyl cellosolve) No Yes 12 Comparison (butyl cellosolve) Yes No 13 Comparison (butyl cellosolve) Yes Yes 14 Comparison H 5 Yes No 15 Comparison H 5 Yes Yes Yes

The following items were evaluated. 1. Dynamic surface tension measurement: FACE, Kyowa Interface Science Co., Ltd.
It measured at 21 degreeC using the automatic dynamic surface tension meter JET-2 type. 2. Viscosity measurement: Tokyo Keiki Co., Ltd. E type viscometer (VISC
ONIC ED type) was used for measurement at 25 ° C. 3. Anti-staining property, entanglement of net part: SLM-RII (Mitsubishi Paper Mills) for silver salt printing plate as printing plate, FNS for PS plate,
FPS (Fuji Photo Film Co., Ltd.), F Gloss Indigo Blue (made by Dainippon Ink and Chemicals) as ink, HEIDEL for printing machine
Evaluation was performed according to the following criteria using BERG T-OFFSET (TOK model).

Anti-staining property: Number of prints with stains x 500 or less △ 500-1000 sheets ○ 1000 or more

[0026]

[Table 1]

[0027]

According to the present invention, it is possible to provide a dampening liquid which enables lithographic printing plate printing without using IPA.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Ibaraki 3-4 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills (72) Inventor Akio Yoshida 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A polymer containing at least one kind of a nonionic surfactant represented by the following general formula [I] and a polymer represented by the general formula [II]. A dampening liquid composition for lithographic printing. [Chemical 1] (R represents an alkyl group having 1 to 9 carbon atoms, n ₁ and n ₂ are the number of moles necessary for the average molecular weight of the block polymer to be 250 or more, and n ₁ / n ₂ = 0.5-2 (2) (M is a number such that the molecular weight of the polymer corresponds to 2000-50000.)