JPH0552864B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to a colored ink additive for lithographic printing. (B) Prior art and its problems A lithographic printing plate consists of an oleophilic image area that accepts oil-based ink and an oil-repellent non-image area that does not accept ink, and generally the non-image area accepts water. Composed of hydrophilic parts. Therefore, in normal lithographic printing, both ink and water are supplied to the plate surface, the image area selectively receives colored ink and the non-image area selectively receives water, and the ink on the image area is transferred to a substrate such as paper. This is done by being transcribed into . Lithographic printing plates that use dampening water include presensitized plates (so-called PS plates) that use diazonium compounds,
Planographic printing plates based on an electrophotographic method using zinc oxide or an organic photoconductor, and planographic printing plates based on a silver salt photographic method using a silver halide emulsion as a photosensitive component are known. A wide variety of inks are known for use in printing. However, with conventional printing inks, even if good prints can be obtained when using a specific printing plate or dampening solution, the type and printing conditions may change. Depending on the situation, various drawbacks may occur, and in some cases, it may not be possible to use it at all. It goes without saying that the properties required of such printing ink are that a sufficient amount of ink adheres to the printed areas and that no ink adheres to non-printed areas. Furthermore, it is necessary to consider fluidity, interfacial suitability, drying properties, etc. Especially in lithographic printing,
While oil-based ink and water are printing thousands to tens of thousands of sheets,
Since the ink is repeatedly supplied to the printing plate for each sheet, if the interfacial tension and surface tension between the oil-based ink and water are not properly balanced, the printed area will gradually expand or disappear. , an oil-based ink with excellent interfacial suitability is required to prevent ink emulsification and background smearing. However, conventional lithographic printing inks cannot be said to have sufficient interfacial suitability, resulting in various drawbacks as mentioned above, and are not sufficiently versatile with respect to various plate materials and dampening solutions. . In particular, many color inks used for color printing other than black ink, unlike carbon black, use relatively hydrophilic pigments, which cause emulsification during printing and cause background smudges, making it difficult to reproduce good tone. It has the serious drawback that it cannot be used at all. (C) Object of the invention The object of the invention is to provide an additive for obtaining an improved lithographic printing colored ink free from the above-mentioned problems. (D) Structure of the Invention The above object of the present invention is an ink additive to be added to a colored ink for lithographic printing, which additive is a compound having an alkylene oxide unit and an HLB value of 3 to 13. This was achieved with the above ink additive consisting of: The ink additives of the present invention can be added to commercially available lithographic printing inks, or can be added to the ink vehicle during ink manufacture. A preferred embodiment of the ink additive of the present invention, when added to a lithographic printing ink (usually commercially available) containing at least a pigment and a vehicle ink base, is a resin that is miscible with the vehicle of the ink (vehicle). ) and the above compound. The reason for this is that compared to adding only the above compounds, it is possible to minimize changes in properties such as fluidity and drying properties of the ink, and it is also possible to add them on the printing press. by. The compound which is the ink additive of the present invention is represented by the following general formula, and has an HLB value of 3 to 13,
Preferably it is a compound of 5 to 12. General formula R(-A) _n --OH (R is an aliphatic or aromatic hydrocarbon group, A
represents an alkylene oxide group, m is 1 to 6
indicates an integer. The HLB value is the value obtained by dividing the weight (%) occupied by alkylene oxide groups in the molecule by 5. Representative compounds are shown below.

【table】

[Ink additives A to G]

Exemplary compounds 1, 2, 3, 4, 5, 8, and 13 each at 100 parts by weight per 100 parts by weight of rosin-modified phenolic resin.
The kneaded parts by weight are referred to as ink additives A to G in this order. The printed results are shown in Table 1.

[Table] The inks to which the ink additives A to G of the present invention were added showed no background smudge even after printing 5,000 sheets or more, and good printed matter with high ink density was obtained. For reference, Exemplified Compound 3 and Exemplified Compound 9
The above-mentioned moisturizing liquid was added at a rate of 5 g/each,
As a result of printing using F gloss purple as the printing ink, the staining evaluation was "x" in all cases. For comparison, diethylene glycol monomethyl ether was used as an ink additive in the same manner as in Example 1, and when printing was performed, the stain evaluation was x in all cases. Example 2 50 parts by weight each of Exemplary Compounds 3 and 9 were added to 100 parts by weight of a silicone-modified alkyd resin and kneaded to prepare two types of ink additives. When a blank was tested in accordance with Example 1 using only the above alkyd resin, the stain evaluation of the blank was △, and all the ink additives of the present invention were rated ◎. Example 3 Three types of commercially available ink compositions for color printing with different ink tack values and colors were mixed with 10% by weight of the ink additives D and F of the present invention used in Example 1, and an ink with no additives was added. When printing was performed using commercially available inks, the same effects as those obtained in Example 1 were obtained in all cases. Example 4 Example 1 was repeated using a commercially available PS plate and a printing plate using zinc oxide, each using their own dampening water. A remarkable difference was observed in all planographic printing plates. Example 5 The test on the PS version of Example 4 was repeated. However, UV ink (Toyo Ink FD0) is used as ink.
3% of the ink additive of Example 1 was added to the ink and printed with a high-speed off-wheel. High-density printed matter was stably obtained. (F) Effects of the Invention The ink additive of the present invention improves interfacial suitability and prevents staining by adding a small amount to printing ink, almost independently of the type of lithographic printing ink and plate material. It is particularly useful for color printing inks.

Claims (1)

[Claims] 1. An ink additive to be added to a colored ink for lithographic printing, which is represented by the following general formula:
A colored ink additive for lithographic printing characterized by comprising a compound having an HLB value of 3 to 13. General formula R(-A) _n --OH (R represents a substituted or unsubstituted aliphatic or aromatic hydrocarbon group, A represents an alkylene oxide group, and m represents an integer of 1 to 6.) 2 The colored ink additive according to claim 1, which is a composition of the compound and a vehicle that is miscible with the vehicle of a colored ink for lithographic printing.