JP2001262030A - Lithographic printing ink additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for obtaining a lithographic printing ink which improves the interfacial compatibility of an ink by leaps and bounds and can prevent the scumming of nonimage portions without adversely affecting the ink spread of image portions. SOLUTION: (1) The lithographic printing ink additive comprises a polyoxyethylene sorbitan fatty acid ester compound or a polyoxyethylene sorbitol fatty acid ester compound. (2) The lithographic printing ink additive comprises a compound having two or more sulfonic groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an ink additive for lithographic printing.

[0002]

2. Description of the Related Art A lithographic printing plate comprises an oleophilic image portion which receives oily ink and an oil-repellent non-image portion which does not accept ink, and the non-image portion generally comprises a hydrophilic portion which receives water. . Therefore, in normal lithographic printing, both ink and water are supplied to the plate surface, the image portion selectively receives the coloring ink and the non-image portion selectively receives the water, and transfers the ink on the image to a substrate such as paper. It is done by being done.

As a lithographic printing plate using a humidifying solution, a presensitized plate (PS) using a diazonium compound is used.
Plate), an electrophotographic lithographic printing plate using zinc oxide or an organic photoconductor, and a silver halide lithographic printing plate using a silver halide emulsion as a photosensitive component. A wide variety of inks used for printing on a printing plate are known.

However, in the case where the conventional printing ink is a specific printing plate or a humidifier,
Even if a good printed matter can be obtained, various kinds of disadvantages are caused by changes in the kind and printing conditions, and in some cases, it cannot be used at all.

It is needless to say that it is important for such printing inks that a sufficient amount of ink adheres to the image area and no ink adheres to the non-image area. However, it is necessary to further consider flowability, interface suitability, drying property, and the like. In particular, in lithographic printing, oil-based ink and water are used during printing of thousands to tens of thousands of sheets.
Since it is repeatedly supplied to the plate surface for each sheet, if the interfacial tension and the surface tension between the oil-based ink and water do not have an appropriate balance, the image area gradually expands or disappears, In order to cause emulsification of the ink and to cause soiling, an oil-based ink having excellent interface suitability is required.

Japanese Unexamined Patent Publication (Kokai) No. 61-138677 discloses an ink additive for lithographic printing comprising a compound having an alkylene oxide unit and having an HLB value of 3 to 13. Certainly, the compounds shown in this patent give good interface suitability to the ink and can prevent background fouling,
Depending on the type of lithographic printing material, ink, humidifier, printing machine, water supply mechanism, etc., it was not yet sufficient.

For example, when a silver salt printing plate having a lower water retention than a PS plate is printed by a printing machine having a water supply mechanism of a continuous water supply type, a background stain is generated, and by adding the compound described in the above patent to the ink, the background is reduced. Although dirt can be reduced, its effect is not enough.

On the other hand, it is well known that fine particles having an average particle size of 0.1 μm (μ) or less, such as colloidal silica, are used in various plate surface treatment solutions subsequent to the development processing of such a silver halide lithographic printing plate. . For example, JP-A-48-45
305, a neutralizing solution of JP-A-54-83502, a neutralizing solution of Japanese Patent Application No. 55-104176, a desensitizing solution, a moisturizing solution, a fixing agent (liquid) of Japanese Patent Publication No. 45-90001, A plate surface treating solution such as a wet solution, a humidifying solution described in JP-A-59-31193, and a plate surface treating solution described in JP-A-7-56349.

However, it is generally considered that inorganic fine particles such as colloidal silica and colloidal alumina are adsorbed on the surface of a lithographic printing plate to form a hydrophilic layer on the surface of the printing plate, thereby improving hydrophilicity. The lithographic printing plate has not yet sufficiently achieved the most desired purpose of preventing staining with printing ink, but also has a serious drawback that it hinders ink application on the image area. Therefore, there has been a demand for the development of a technique that does not cause background fouling even without using such inorganic fine particles.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing ink which can drastically improve the interfacial suitability of an ink and can prevent background stains in a non-image area without impairing the ink application in the image area. To provide an additive for Another object of the present invention is to provide an ink additive that can prevent background fouling very effectively in a printing machine equipped with a continuous water supply mechanism that easily causes background fouling. Still another object of the present invention is to provide an ink additive that can prevent background fouling even when a plate surface treatment liquid containing no inorganic fine particles is used.

[0011]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
This was achieved by the following ink additives (1) and (2). (1) A lithographic printing ink additive comprising a polyoxyethylene sorbitan fatty acid ester compound or a polyoxyethylene sorbite fatty acid ester compound. (2) A lithographic printing ink additive comprising a compound having two or more phosphonic acid groups.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyoxyethylene sorbitan fatty acid ester compound or polyoxyethylene sorbite fatty acid ester compound used in the present invention is produced by an esterification reaction between sorbitan or sorbite having an ethyleneoxy group and a higher fatty acid. A group of non-ionic surfactants. The repeating unit of the ethyleneoxy group is 5 or more, a total of 5 to 180, and the fatty acid preferably has 10 or more carbon atoms. For example, lauric acid, palmitic acid, stearic acid, oleic acid and the like are used. Fatty acid esters can take the form of mono, di, tri, tetra and the like.
Examples of the polyoxyethylene sorbitan fatty acid ester include Nikkol TP-10 and Nikko Chemical Co., Ltd.
S-10, TS-30, TO-10, TO-30
Nonionic LT-221 and P
T-221, ST-221 and OT-221. Nichol GO-460 and GS-460 are commercially available as polyoxyethylene sorbite fatty acid esters. Hereinafter, typical compounds used in the present invention will be described, but the present invention is not limited thereto.

[0013]

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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Specific examples of the compound having two or more phosphonic acid groups used in the present invention are described below. The following compounds can be obtained as commercial products from various manufacturers.

[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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The ink additive of the present invention can be added to a commercially available lithographic printing ink, and can also be added to a vehicle of the ink during ink production. Furthermore, when added to a lithographic printing ink (usually commercially available) containing at least a pigment and a vehicle ink base, a composition of a resin (vehicle) miscible with the vehicle of the ink and the compound of the present invention. Can also be added.

Examples of the vehicle include conventional lithographic printing vehicles such as drying oil, synthetic drying oil, rosin, copal, and the like.
Natural or processed resin such as dammar, shellac, cured rosin, rosin ester, soybean oil, phenolic resin, rosin-modified phenolic resin, 100% phenolic resin, maleic acid resin, alkyd resin, petroleum resin, vinyl resin, acrylic resin, polyamide resin , An epoxy resin, an aminoalkyd resin, a polyurethane resin, an aminoblast resin and the like are preferable.

The ratio of the compound of the present invention to the vehicle may be in any range, but is generally preferably in the range of 1: 0.5 to 1: 5 (weight ratio).

The amount of the compound of the present invention to be added to the lithographic printing ink varies depending on the type of the ink, the type of the printing plate, and the like, but may be in the range of about 1 to about 10% by weight.

The ink additive of the present invention may contain various additives used in lithographic printing inks, for example, a plasticizer, a stabilizer, a drying agent, a thickener, a dispersant, a filler and the like.

The ink additive of the present invention can be applied to any lithographic printing plate and lithographic printing ink which is subjected to offset printing using a humidifying liquid, regardless of their type. In addition, a wide variety of humidifiers can be used, and not only ordinary water but also conventionally known substances such as desensitizing accelerators, buffers, preservatives, and wetting agents are generally used. Can be mixed to modify the processing activity.

For example, gum arabic, carboxymethyl cellulose, sodium alginate, polyvinyl pyrrolidone, polyvinyl imidazole, a copolymer of polymethyl ether and maleic anhydride, carboxymethyl starch,
Ammonium alginate, oxydide cellulose alginate, methyl cellulose, sulfate (sodium sulfate,
Ammonium sulfate), phosphoric acid, nitric acid, nitrous acid, tannic acid and salts thereof, polyol compounds having two or more hydroxy groups (polyethylene glycol, ethylene glycol, propylene glycol, glycerol, diethylene glycol, hexylene glycol, etc.), organic Weak acids (citric, succinic, adipic, tartaric,
Ascorbic acid, propionic acid, etc.), polyacrylic acid, propylene glycol alginate, aminopolycarboxylic acid (such as sodium ethylenediaminetetraacetate), inorganic colloid (such as colloidal silica), surfactant (nonionic interface having ethylene oxide) Activator, etc.), an antifoaming agent or the like can be added.

In addition to the above, phthalocyanine dyes, malachite green,
A trace amount of a coloring agent such as ultramarine can also be added.

[0040]

EXAMPLES The present invention will be described below with reference to examples, but is of course not limited thereto.

Example 1 A matted layer containing silica particles having an average particle size of 5 μm was provided on one side of a polyester film support having been subjected to a subbing treatment, and an amount of carbon black having an optical reflectance of 3% was provided on the opposite side. An anti-halation undercoat layer (adjusted to pH 4) containing 20% by weight of silica powder having an average particle size of 3.5 μ with respect to photographic gelatin, and silica having an average particle size of 3.5 μ after chemical sensitization. A high-sensitivity silver chloride emulsion (adjusted to pH 4), which was spectrally sensitized in the green region and contained 5% by weight of powder relative to photographic gelatin, was provided.

The gelatin for the undercoat layer was applied at a rate of 3.5 g / m ² , the gelatin for the emulsion layer was applied at a rate of 0.8 g / m ² , and the silver halide was converted to silver nitrate at a rate of 1.0 g / m ² . The undercoat layer and the emulsion layer contain formalin as a hardening agent in an amount of 5.0 mg / g gelatin based on gelatin. After drying, the mixture was heated at 40 ° C. for 5 days.
A lithographic printing plate is manufactured by applying and drying the core coating solution described in No. 31. The silver halide emulsion contains 1 silver halide at the time of physical ripening.
It had 4 × 10 ^-6 moles of rhodium chloride added per mole and had an average particle size of 0.4 microns.

The lithographic printing plate precursor thus obtained was image-exposed with a plate-making camera having an image reversing mechanism, and developed at 30 ° C. for 30 seconds with the following developing solution (used solution). <Developer> Sodium hydroxide 24 g Potassium hydroxide 8 g Anhydrous sodium sulfite 50 g 2-Methyl-2-amino-1-fluoroethanol 30 g 3-Mercapto-4-acetamit-5-n-heptyl-1,2,4-triazole 0 Make up to 1 l with 2 g water.

After the above-mentioned development processing, processing was performed at room temperature for 20 seconds with a neutralizing solution (stabilizing solution) as shown below. The image exposure, development and neutralization stabilization treatments used a plate making camera processor CP-286S manufactured by Mitsubishi Paper Mills, Ltd.

<Neutralizing solution> Phosphoric acid 1.2 g Sodium monophosphate 25 g Anhydrous sodium sulfite 2.5 g 2-Mercapto-5-n-heptyl-oxasiasol 0.1 g Diethanolamine 5 g Make up to 1 liter with water. (Adjusted to pH 6)

The printing plate prepared by the above operation is set in an offset printing press, and the printing press has a continuous water supply type water supply device. The ink is New Champion 68 Purple S type, manufactured by Dainippon Ink. Using a humidifying solution as shown below, etching was performed with tap water, and printing was performed (blank).

<Humidifier> O-phosphoric acid 10 g Nickel nitrate 5 g Ethylene glycol 100 g Water was added to make 20 l. At the time of use, 5% by volume of isopropyl alcohol was added to obtain a working solution.

The test was carried out on a new champion 68 purple S type ink using the compound of the present invention, compound 3, compound 6, compound 13, compound 13 of the present invention.
And the following comparative compounds (a), (b),
About 3% by weight of each of (c) and (d) was kneaded and printed in the same manner.

[0049]

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[0050]

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[0051]

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[0052]

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As a result of printing with the blank ink, a dark background stain was generated on the entire surface. The ink to which the ink additive of the present invention was added did not cause any background stain, and a good printed matter having a high ink density was obtained, and the effect was extremely remarkable. All of the four types of comparative compounds showed an effect of preventing background stain on blanks, but were completely unsatisfactory as compared with the ink additive of the present invention.

Example 2 Example 1 was repeated using Toyo King Hi-Echo 5K Red M type manufactured by Toyo Ink as an ink for lithographic printing. The results were exactly the same as in Example 1.

Example 3 Example 1 was repeated using diatone eco-pure SOY black M type manufactured by Sakata Inx as an ink for lithographic printing. The results were exactly the same as in Example 1.

Example 4 Example 1 was repeated using a mixture of the compound of the present invention and a comparative compound kneaded with the same amount of a rosin-modified alkylphenol resin as an ink additive. The results were exactly the same as in Example 1.

Example 5 Example 1 was repeated, except that the printing plate was changed to a commercial PS plate.
The blank ink and the ink to which the comparative compound was added caused light background staining, but the ink to which the ink additive of the present invention was added did not cause background staining at all, and was a good printed matter having a high ink density.

[0058]

According to the present invention, background contamination can be prevented very well even in ink, plate material, and a water supply mechanism in which background contamination is likely to occur, and a good printed matter having a high ink density can be obtained. Further, since the plate surface treatment liquid does not necessarily require inorganic fine particles such as colloidal silica, a printed material having a higher ink concentration can be obtained.

Claims (2)

[Claims] A lithographic printing ink additive comprising a polyoxyethylene sorbitan fatty acid ester compound or a polyoxyethylene sorbite fatty acid ester compound. 2. A lithographic printing ink additive comprising a compound having two or more phosphonic acid groups.