JPH0552865B2 - - 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 depending on a particular printing plate or dampening solution, the type and printing conditions change. This results in various disadvantages, 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. Particularly in planographic printing, oil-based ink and water are repeatedly supplied to the plate surface for each printing page during the printing of thousands to tens of thousands of sheets, so the interfacial tension and surface tension between the oil-based ink and water If the ink is not properly balanced, the printed area will gradually expand or disappear, emulsification of the ink, and background smearing will occur, so an oil-based ink with excellent interfacial compatibility is required. shall be. 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 stains, making it difficult to reproduce good tone. It has the serious drawback that it cannot be used at all. Furthermore, colored inks for lithographic printing generally have higher viscosity (low fluidity) and poor drying properties than printing inks for other uses.
This is undesirable for speeding up printing.
Therefore, there is a need for additives that can improve fluidity and drying properties as well as interfacial suitability. (C) Object of the invention The object of the invention is to provide an additive for obtaining a colored ink for lithographic printing having improved flowability, drying properties and interfacial suitability. (D) Structure of the Invention The above object of the present invention is to provide an ink additive to be added to the vehicle of a lithographic printing ink, the additive comprising an alkylene oxide unit and a hydrocarbon having 1 to 8 carbon atoms. By the above ink additive consisting of a combination of at least one compound having a group and at least one compound having an alkylene oxide unit and a hydrocarbon group having 9 or more carbon atoms (average HLB value 3 to 13). achieved. The present invention will be explained in more detail below. 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. According to etc. In addition, the ink additive in this embodiment is preferably one with a fluidity higher than that of the commercially available lithographic printing ink, which has a high viscosity, so that it can be easily mixed with the commercially available lithographic printing ink. has the advantage that there is a greater variety of vehicles from which to choose to impart such properties. It is preferable that at least two of the above-mentioned compounds are selected from among the compounds represented by the following general formula as the ink additives of the present invention. 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 from 1 to 9.) HLB The value is the weight (%) occupied by alkylene oxide groups in the molecule divided by 5. In the compound of the general formula, compounds in which R has a C1-8 hydrocarbon group (e.g. alkyl, aryl) (group A) and compounds in which R has a _C9 or more hydrocarbon group (e.g. alkyl, aryl) (group B) ) preferably have an HLB value in the range of 1 to 15,
HLB value (average value) of group A and group B combined is 3~
13, preferably 5 to 12. Representative compounds are shown below. [Group A] (A-1) Ethylene glycol monomethyl ether (A-2) Ethylene glycol monoethyl ether (A-3) Ethylene glycol monobutyl ether (A-4) Diethylene glycol monomethyl ether (A-5) Diethylene glycol monoethyl ether ( A-6) Diethylene glycol monobutyl ether (A-7) Diethylene glycol monophenyl ether (A-8) Propylene glycol monobutyl ether [group B] (B-1) Ethylene glycol-mono-P-nonylphenyl ether (B-2) Diethylene glycol-mono-P-nonylphenyl ether (B-3) Triethylene glycol-mono-P-nonylphenyl ether (B-4) Tetraethylene glycol-mono-P-nonylphenyl ether (B-5) Penta Ethylene glycol-mono-P-nonylphenyl ether (B-6) Heptaethylene glycol-mono-P-nonylphenyl ether (B-7) Octaethylene glycol-mono-P-nonylphenyl ether (B-8) Triethylene glycol mono-dodecyl ether (B-9) Tetraethylene glycol-mono-P-octyl phenyl ether (B-10) Pentaethylene glycol-mono-P-
Dodecyl phenyl ether The [Group A] and [Group B] compounds used are preferably a combination of compounds in which the number of carbon atoms of R in the above general formula differs from each other by 3 or more, preferably 5 or more.
Although the ratio can be changed arbitrarily depending on the desired characteristics of the ink, it is generally 1:5 to 5:1.
(molar ratio) is preferable. Further, ink solvents such as Nisseki No. 0, No. 5, and No. 6 may also be used as necessary. As already mentioned, the ink additives of the present invention combine the above compounds with conventional lithographic vehicles, such as drying oils, synthetic drying oils, natural or Processed resin, phenolic resin, rosin modified phenolic resin, 100% phenolic resin,
Those kneaded with maleic acid resin, alkyd resin, petroleum resin, vinyl resin, acrylic resin, polyamide resin, epoxy resin, aminoalkyd resin, polyurethane resin, aminoplast resin, etc. are preferred. The ratio of the compound 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 added to the lithographic printing ink varies depending on the type of ink, the type of plate material, etc., but can be in the range of about 1 to about 10% by weight. The ink additives of the present invention may also contain various other additives used in lithographic printing inks, such as plasticizers, stabilizers, desiccants, thickeners, dispersants, and fillers. The ink additive of the present invention can be applied to any type of lithographic printing plate or lithographic printing ink that performs offset printing using dampening water. In addition, a wide variety of dampening solutions can be used, including not only ordinary water but also conventionally known substances such as desensitization accelerators, buffering agents, preservatives, and wetting agents. can be mixed to modify treatment activity. For example, gum arabic, carboxymethylcellulose, sodium alginate, polyvinylpyrrolidone, polyvinylimidazole, polyvinylmethylether and maleic anhydride copolymer, carboxymethylstarch, ammonium alginate, cellulose alginate oxide, methylcellulose, sulfates (sodium sulfate, ammonium sulfate) etc.), phosphoric acid, nitric acid, zinc acid, tannic acid and their salts,
Polyol compounds having two or more hydroxy 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, propionic acid, etc.), polyacrylic acid, ammonium dichromate, chromium alum, alginic acid One or more of propylene glycol esters, aminopolycarboxylic acid salts (ethylenediaminetetraacetic acid sodium salt, etc.), inorganic colloids (colloidal silica, etc.), surfactants, and the like can be added. In addition, water-miscible organic solvents such as methanol, dimethylformamide, and dioxane, as well as phthalocyanine dyes,
Small amounts of colorants such as malachite green and ultramarine can also be added. (E) Examples The present invention will be explained below using typical examples, but the present invention is not limited in any way. Example 1 A lithographic printing plate (manufactured by Mitsubishi Paper Industries; Silver Master) using the silver complex diffusion transfer method was subjected to image exposure and plate-making processing, and then installed in an offset printing machine, using a special desensitizing liquid and a dampening liquid. I printed it. Printing ink is F gloss purple A (manufactured by Dainippon Ink)
is used as a blank, and the following ink additives A~
5% by weight of E was added and kneaded to prepare an ink. [Ink additives A to E] Exemplary compounds are kneaded per 100 parts by weight of rosin-modified alkylphenol resin as shown in the table below to obtain ink additives A to E. Figures in parentheses indicate parts by weight.

[Table] Evaluation was made based on the following criteria based on the number of sheets printed when printing was impossible due to background smearing when printed using an offset printing machine. ×…1000 sheets or less △…5000 sheets or less ○…10000 sheets or more Table 1 shows the results of scumming.

[Table] In addition, ink containing ink additives A and B has too low a viscosity and is difficult to handle, causing flow on the ink roller, but it also dries too quickly.
There was a problem with stability on the plane. Inks containing ink additives D and E are easy to handle and have excellent on-press stability, with no background smearing even after printing more than 10,000 sheets, and high density with excellent reproduction of continuous tone. It was a printed matter. Example 2 An ink additive was prepared by adding the exemplified compounds shown in the table below to 100 weight of silicone-modified alkyd resin, and the procedure of Example 1 was then followed. All Example 1
The same results as ink additives D and E were confirmed.

[Table] Example 3 Three commercially available ink compositions for color printing with different ink tack values and colors were mixed with 3% by weight of the ink additives D and E of the present invention used in Example 1 and thoroughly kneaded. When printing was performed using a commercially available ink containing no additives, the same results as those obtained in Example 1 were obtained in both cases. Example 4 Examples 1 and 2 were repeated using a commercially available PS plate and a printing plate using zinc oxide, respectively, using dedicated dampening solutions. Similar significant differences were observed. (F) Effects of the Invention The lithographic printing ink containing the ink additive of the present invention has superior fluidity, drying properties, and interfacial suitability, and is easier to handle on a printing press than the ink without the additive. In addition to this, you can get a large number of high-quality prints.

Claims (1)

[Scope of Claims] 1. An additive represented by the following general formula to be added to a colored ink for lithographic printing, wherein the additive is a compound having an alkylene oxide unit and a hydrocarbon group having 1 to 8 carbon atoms. A colored ink additive for lithographic printing, comprising a combination of at least one of the above and at least one compound having an alkylene oxide unit and a hydrocarbon group having 9 or more carbon atoms and having an average 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 8.)