JP2803248B2 - Desensitizing ink for lithographic printing without water - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a desensitizing ink for waterless lithographic printing which is preferably used when performing waterless lithographic printing on pressure-sensitive copying paper or the like.

[Prior Art] Conventionally, printing of desensitizing ink for pressure-sensitive copying paper has been performed by a relief printing method, an intaglio printing method, a lithographic printing method, a stencil printing method, and the like. There is a shift from intaglio printing to lithographic printing.
The reason for this is that plate making is easier in lithographic printing than in letterpress printing, etc., the dimensional accuracy is high, and because the printing pressure is low, the microcapsules for coloring formed on the back side of the pressure-sensitive copying paper are used. The printing quality is excellent because the ink film is not broken and the ink film thickness is uniform. However, in wet lithographic printing, the pigments and desensitizers contained in the desensitizing ink contain many hydrophilic substances, so that the ink has a high affinity for the dampening solution, and as a result, the ink is emulsified with the dampening solution during printing. On the contrary, since the ink is mixed with the dampening solution, the background becomes dirty in the non-image area, and printing becomes difficult. Attempts have been made to improve desensitizing inks to eliminate such problems, but no satisfactory ink has yet been obtained.

On the other hand, lithographic printing without water using fountain solution is conceivable as a method for solving such problems, but a desensitizing ink for lithographic printing without water has not been developed yet. Here the conventional
If the desensitizing ink for PS (wet lithographic printing plate) is used for waterless lithographic printing as it is, there will be no ink repulsion with non-image areas on the plate surface, and there will be many troubles such as background contamination and curling of paper. Cannot be printed.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object the advantage of having no practical water with good ground stain resistance and excellent printability. It is to obtain a desensitizing ink for lithographic printing.

[Means for Solving the Problems] The object of the present invention has been attained by a desensitizing ink for waterless lithographic printing mainly comprising a resin having a weight average molecular weight of 5,000 or more, a solvent having a boiling point of 200 ° C. or more, and a desensitizer. Is done.

That is, the desensitizing ink for lithographic printing without water of the present invention is:
It is mainly composed of a natural or synthetic resin having a weight average molecular weight of 5,000 or more, a solvent having a boiling point of 200 ° C. or more, and a desensitizer generally used in conventional desensitizing inks.

Examples of the resin used in the present invention include oil-soluble phenol resins and modified phenol resins modified with these polycarboxylic acids or anhydrides thereof, ketone resins,
Examples include polyamide resin, maleic acid resin, petroleum resin, and alkyd resin. The weight average molecular weight of the resin used needs to be 5,000 or more, more preferably 10,000 or more, and further preferably 50,000 or more. If the weight-average molecular weight of the resin is less than 5,000, the resulting ink has low ground stain resistance, which is not preferable. The upper limit of the weight average molecular weight is not particularly limited, but is preferably 500,000 or less from the viewpoint of the solubility of the resin and the ink flowability.

Examples of the resin satisfying the above conditions include “Tanomaru” 350 or KG801 (both are rosin-modified phenolic resins manufactured by Arakawa Chemical Co., Ltd.), “Tespol” 6301 (rosin-modified phenolic resin manufactured by Hitachi Chemical Co., Ltd.), "Neoresin" N569 (a petroleum resin manufactured by Hitachi Chemical Co., Ltd.) and "Solid Peccosol" (an alkyd resin manufactured by Dainippon Ink Co., Ltd.) and the like. These resins can be used alone or as a mixture, but in practical use, it is preferable to use a light-colored resin that does not color ink as much as possible.

The solvent used in the present invention has a boiling point of 200 ° C. or higher,
Preferably a petroleum-based solvent at 200 to 350 ° C, and α
A hydrocarbon solvent having a branched chain at the 1-position, that is, an α-olefin solvent. For example, "Diaren 168" (manufactured by Mitsubishi Yuka Co., Ltd.) can be mentioned. By using such α-olefin alone or mixed with another general solvent, for example, a solvent containing 5% by weight or less of aromatics, an ink having low tackiness and high ground stain resistance can be obtained. be able to.

Known desensitizers can be used as the desensitizer in the present invention. For example, as described in JP-B-33-3921, cationic quaternary ammonium salts (such as dodecyltrimethylammonium chloride) and JP-B-46-29546 can be used. Tertiary amines having two polyethylene oxide groups (such as N, N-di-polyoxyethyleneethylamine) as described in JP-A-47-38201 and polyoxyethylene monoalkyl esters (poly-ethylene) as described in JP-B-47-38201 Oxyethylene oleyl ester) and polyethylene glycol alkyl phenyl ether (such as polyethylene glycol nonyl phenyl ether) described in JP-B-49-8288.

Alternatively, the resilience of the ink with a waterless lithographic plate can be improved by esterifying the terminal -OH of the desensitizer with a higher fatty acid.

Known fillers can be added to the ink of the present invention. Examples of the filler include titanium oxide, zinc oxide, barium sulfate, magnesium carbonate, calcium carbonate, barium carbonate, magnesium hydroxide, silica, and talc. These fillers can be subjected to various lipophilic treatments for the purpose of improving the ink repellency during lithographic printing without water.

In the desensitizing ink for lithographic printing without water of the present invention, it is important not to use an oil component such as a drying oil used in a general oil-based ink. Addition of these oil components not only reduces the desensitizing effect of the ink, but also impairs the ink setting property immediately after printing. In addition, printing with a large picture area due to a large tack value of the ink is not preferable because a printing paper rolls up.

It is preferable that the resin used in the ink of the present invention is subjected to elongation of the molecular chain with an amine compound containing an active hydrogen, which is a molecular chain elongation agent, during varnish formation as described below.

Examples of the amine compound having active hydrogen used as a molecular chain extender include monoamines such as ethylamine, n-butylamine, n-propylami, hexylamine, laurylamine, stearylamine, ethanolamine, and allylamine, ethylenediamine, trimethylenediamine. And diamines such as tetramethylenediamine, pentamethylenediamine and hexamethylenediamine; polyamines such as diethylenetriamine, triethylenetetramine and bishydroxydiethylenetriamine; and derivatives thereof.

Here, the term “molecular chain extension” means to increase the molecular weight of the resin by a chemical reaction. Therefore, by using a compound having two or more reactive groups, such as an amine compound having active hydrogen, as a molecular chain extender, two or more reactive groups are reacted with a functional group present on a polymer terminal or a polymer side chain. It works to connect different polymers. Examples of such a molecular chain extender include an amine compound having active hydrogen,
Examples thereof include polybasic acids or anhydrides thereof, and isocyanates. Among them, amine compounds having active hydrogen can be most preferably used. For example, when an amine compound having active hydrogen as a molecular chain extender and a phenol resin as a resin, a phenolic hydroxyl group of the phenol resin reacts with an amino group of the molecular chain extender,
The molecular chain of the phenolic resin is extended.

As a method of preparing the ink, for example, a resin and a solvent
Dissolve by applying heat of at least ℃, stir until the mixture becomes uniform, lower to around 100 ℃, then add a desensitizer to make a varnish. At this time (when the temperature is lowered), it is preferable to add, as an additive, at least one kind of molecular chain extender selected from the group of an amine compound having active hydrogen, an acid anhydride, and an isocyanate. Other reactive silicone oils or non-reactive silicone oils may be added. To the varnish thus prepared, fillers such as white pigments and extender pigments, solvents, various surfactants, waxes, and plasticizers such as dioctyl phthalate and fatty acid esters of sebacic acid, if necessary, are added. After mixing well, the ink can be obtained by kneading well with three rolls. The desensitizer can be added when the ink is formed.

The proportions of these components are not particularly limited, but preferably 20 to 60% by weight of a desensitizer, 10 to 40% by weight of a resin, 5 to 30% by weight of a solvent, 10 to 60% by weight of a filler, and other additives. Agent 1 to 20% by weight.

[Examples] Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

The soil resistance, paper suitability and desensitization characteristics in the examples were evaluated by the following methods.

Printing was performed using a waterless planographic printing press VS1000 (manufactured by Toray Engineering Co., Ltd.) at a place where the room temperature was controlled at 20 ° C. As the paper, carbon paper after carbonless (a developer was applied on the surface) was used. Alkaline blue toner (T
-400, manufactured by Morimura Burnish) was added in an amount of 0.5%, and about 1000 copies were printed. In the meantime, it was visually checked whether or not a background stain due to poor ink repulsion occurred in the non-image area, and this was evaluated as the background stain resistance. During this printing, it was checked whether or not a trouble occurred in which the printing paper was wrapped around the blanket cylinder (a solid image with a pattern area ratio of 30%), and this was regarded as paper suitability. Further, the desensitization characteristics were determined by superimposing the B paper on the printed C paper and printing with a typewriter, and checking the state of blue and black color development.

Example 1 Rosin-modified phenolic resin ("Tespol" SPR130,
Weight average molecular weight 190,000, manufactured by Hitachi Chemical Co., Ltd.) 60% by weight
And petroleum-based solvents ("Dialen" 168, manufactured by Mitsubishi Petroleum Corporation)
10% by weight is heated and dissolved in a separa flask. Stir at 240 ° C for 30 minutes in an oil bath to obtain a uniform solution. Next, the temperature of this solution was lowered to 150 ° C., and the end of the 4-mol adduct of polypropylene glycol ethylene oxide was added thereto.
28% by weight of 1/6 oleic acid ester of OH group and 2% by weight of polyamidoamine ("Persamide" 125, manufactured by Henkel Hakusui) are added and stirred and mixed for 30 minutes to form a varnish. Furthermore, 55% by weight of the varnish was taken, and 32% by weight of titanium oxide, 10% by weight of calcium carbonate, and 3 parts of "Dialen" 168 were added.
% By weight and kneaded well with a three-roll mill to produce Ink-1. Printing was performed on this ink, and the ground stain resistance, paper suitability, and desensitization characteristics were evaluated. Table 1 shows the results.

Example 2 55% by weight of a varnish prepared in the same manner as in Example 1 except that 2% by weight of maleic anhydride was added instead of polyamidoamine, and 32% by weight of titanium oxide was added thereto.
And 10% by weight of calcium carbonate and "Dialen" 168 were added and kneaded well with a three-roll mill to prepare Ink-2. The same evaluation was performed on this ink, and the results are shown in Table 1.

Comparative Example 1 Ink-1 was prepared in exactly the same manner as in Example 1 except that epoxy acrylate ("Lipoxy" VR-60, weight average molecular weight 1950, manufactured by Showa Polymer Co., Ltd.) was used instead of the rosin-modified phenol resin. The results were shown in Table 1.

Comparative Example 2 In Example 1, the boiling point was changed to "Dialen" 168.
Ink-4 was prepared in exactly the same manner except that Clensol (a petroleum solvent manufactured by Nippon Petrochemical Co., Ltd.) at 150 to 170 ° C. was used, and the same evaluation was performed. The results are shown in Table 1.

Table 1 Ink resistance to ground Smear resistance Paper suitability Desensitization properties 1 ○ ○ ○ 2 ○ ○ ○ 3 × × ○ 4 × × ○ ○ indicates the state where it can be used commercially, and × indicates that it cannot be used commercially. Is shown.

As shown in Table 1, it can be seen that Inks-1 and 2 are excellent as desensitizing inks in waterless lithographic printing. On the other hand, Ink-3 and Ink-4 each have poor paper suitability and ground stain resistance, and can be said to be unsatisfactory as desensitizing inks in waterless lithographic printing.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to obtain a desensitizing ink for waterless lithographic printing that has good ground stain resistance, has excellent printability, and is commercially practical. Was.

Continuation of front page (56) References JP-A-2-142866 (JP, A) JP-A-55-46991 (JP, A) JP-A-59-196374 (JP, A) JP-A-62-18484 (JP) , A) JP-A-62-192477 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09D 11/00-11/14 B41M 5/124-5/165

Claims (2)

(57) [Claims] 1. A desensitizing ink for waterless lithographic printing mainly comprising a resin having a weight average molecular weight of 5,000 or more, a solvent having an α-olefin as a main component and a boiling point of 200 ° C. or more, and a desensitizer. 2. The desensitizing ink for lithographic printing without water according to claim 1, wherein the resin is obtained by extending the molecular chain of an amine compound having active hydrogen.