JP2001335727A - Printing ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a printing ink composition which has an improved emulsification balance, gives stable printed matter, and can decrease the amount of dampening water used. SOLUTION: This ink composition contains 5-30 wt.% water particles having particle diameters of 2-10 μm, is used for keyless newspaper offsets, and includes a printing ink composition containing a rosin-modified phenol resin having a mol.wt. of 50,000-120,000 and an acid value of 25 or lower as a resin component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-emulsified printing ink composition.

[0002]

2. Description of the Related Art Conventionally, in an offset printing process, dampening water is supplied to the surface of a printing plate to form a non-image area, and ink is transferred from an ink roll to an image area that does not carry dampening water. And then transferring the ink layer from the printing plate onto the blanket, and printing from the blanket onto the paper surface as the layer to be printed. Thus, the printing ink reaches the printing plate and blanket from the ink fountain via the inking roll, and is transferred to the printing paper.

[0003] Among them, a keyless printing press is an ink in which a supply ink is emulsified in advance. That is, the ink is transferred to the inking roll, the printing plate, and the blanket, but the ink transferred to the plate is scraped off by the doctor blade attached to the inking roll, and then transferred to the transfer roller. Is supplied to the plate surface with a constant ink film pressure. The scraped ink is already emulsified with the fountain solution supplied on the plate surface and returns to the ink fountain.

[0004] Therefore, in the ink fountain,
Although the ink should be fresh in nature, it becomes an emulsified ink containing fountain solution.

[0005] The fountain solution is dispersed in the ink. However, if the dispersion is not appropriate, the printing of stains (insufficient / excessive emulsification), whitening (excessive emulsification), uneven density, etc. may occur. Trouble arises. Therefore, it is necessary to adjust the supply amount of dampening solution in actual printing. The replenishment of the consumed ink is performed with fresh ink in the fountain. Therefore, within the ink fountain, the fountain solution content
(Emulsification ratio) is different. For this reason, spots are generated in the emulsified ink which is transferred from the fountain to the inking roll, which often causes difficulty in adjusting the supply of the dampening solution and the above-described troubles. Therefore, there is a need for a printing ink composition that is a novel form that is easy to adjust the dampening solution.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the emulsification balance of ink on a printing press of a keyless rotary press, obtain a stable printed product, and further reduce the amount of fountain solution. And an offset printing ink composition.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a water component (water or a fountain solution for printing; hereinafter, abbreviated as a water component) and, in some cases, emulsion stability in a printing ink composition. It has been found that a stable printing paper surface can be easily obtained by an ink composition in which an emulsifying ratio is adjusted in advance by mixing and adding agents, and the present invention has been accomplished.

That is, the constitution of the present invention is a printing ink composition comprising 5 to 30% by weight of water particles having a particle size of 2 μm to 10 μm. Further, the printing ink composition described above is a printing ink composition for keyless newspaper offset. Further, according to the constitution of the present invention, the printing ink composition described above has a molecular weight of 5,000 as a resin component.
A printing ink composition containing a rosin-modified phenol resin having an acid value of 0 to 120,000 and 25 or less is included.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of the printing ink according to the present invention, an ink composition and a water component are mixed in advance with an emulsifier in some cases, and the particle diameter is 2 μm to 10 μm.
This is characterized in that the particles are dispersed so as to have a thickness of μm.

In a conventional printing method including a general newspaper, ink and a water component are separately supplied, emulsified on an ink roller, and the ink is selectively applied to an image portion on a plate surface.
Water components are selectively transferred to non-image areas. However, in the keyless printing method, as outlined, the supplied ink itself is in an emulsified state, and this emulsification stability greatly affects the quality of printing paper surface and the printing workability. Therefore, the fact that the supplied ink itself is a stable emulsified ink is considered to be particularly effective in the case of newspaper keyless offset printing as compared with other offset printing.

As the printing ink used in the present invention, any ink for newspaper offset printing, such as a low-viscosity newspaper offset ink and a keyless newspaper offset ink, is used. To produce the printing ink according to the present invention,
Any of them may be the same as the prior art. For example, a common rosin-modified phenolic resin, alkyd resin, synthetic resin such as petroleum resin, linseed oil, drying oil such as tung oil, etc. Prepare it. Above all, from the viewpoint of printability of a keyless printing machine and measures against stains, a high molecular weight (50,000 to 100,000) is used.
It is preferable to use a rosin-modified phenol resin having a resin acid value of 25 or less as a varnish. Then, it may be produced by a three-roll mill using known pigments such as organic pigments and inorganic pigments, and solvents such as varnish and light oil.

As the water component used in the present invention, a fountain solution containing about 3% of an alkaline or neutral etchant is used as in the case of a general fountain solution for newspaper printing. Essentially, distilled water, ion-exchanged water from a water softener, or the like that does not contain a solute is used.

The addition amount of the water component is 5 to 30% by weight, preferably 15 to 25% by weight. The degree of emulsification can be determined by measuring the emulsified ink with a Karl Fischer moisture meter. The particle diameter of the water component can be roughly confirmed by observing the emulsified ink with a projection-type magnifying microscope.

As a method for dispersing the water component, for example, 80 parts of the printing ink is put into a container capable of stirring and mixing, and the mixture is well dispersed and stirred. To stabilize the emulsion better, it is preferable to add 0.1 to 2% by weight of an ionic or nonionic surfactant. Thereafter, while stirring, 20 parts of a water component are added little by little while checking the state of mixing to obtain an emulsified ink. The example described here is merely an example, and the present invention is not limited to this example.

[0015]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the scope of the present invention is not limited to these examples.

Beccasite 1126 (molecular weight 5500)
0, acid value 23, 40 parts by weight of rosin-modified phenol resin manufactured by Dainippon Ink and Chemicals, 30 parts by weight of linseed oil and 30 parts by weight of light oil (manufactured by Mitsubishi Nisseki) are heated at 250 ° C. for 2 hours to prepare a varnish (A). ) Was prepared. A varnish (B) was prepared by dissolving 54 parts by weight of natural resin Gilsonite (manufactured by Ziggler, USA) in 46 parts by weight of light oil (manufactured by Nisseki Mitsubishi) at 200 ° C.

Next, 20 parts by weight of the varnish (A) and 5 parts by weight of the varnish (B), 20 parts by weight of carbon black (manufactured by Mitsubishi Chemical), mineral oil and light oil (manufactured by Nisseki Mitsubishi) 5
By milling 5 parts by weight with a three-roll mill,
A base ink was manufactured.

In addition, 3 parts by weight of an alkaline etchant Cosmo Fountain 501 (manufactured by Dainippon Ink and Chemicals, Inc.) was dissolved in ion-exchanged water to obtain a water component (C).

Using the base ink adjusted as described above, a trial emulsion ink was manufactured under the conditions shown in Table 1 below.

[0020]

[Table 1]

Note (* 1) As the surfactant, an ionic surfactant SL-10 (manufactured by Nippon Surfactant Co., Ltd.) was used.

(Evaluation of Stability of Emulsified Ink) With respect to the emulsified stability of the inks of Comparative Examples and Examples prepared with the above-mentioned formulations, the state was observed with a projection magnifying microscope. As a specific method, the prototype ink was sandwiched between glass preparations, and its emulsified state was checked with time. The particle size was also investigated. As for the particle size, the particle sizes of ten water components were visually measured, and the average was calculated.

[0023]

[Table 2]

(Printing Test) Using the newspaper inks obtained in Examples 1 to 4 and Comparative Example 1, a newspaper was printed at a printing speed of 120,000 parts / hour on a Miyakoshi 7N-600 newspaper keyless offset printing press. One roll (20,000 copies) was printed. In the ink fountain (fountain) of the printing press, only in Comparative Example 1, printing was started from a state in which the water component (C) was emulsified to 20% by weight in advance. Comparative Example 1 The ink was replenished as it was. In the case of another example, the emulsified ink was put into the ink fountain from the start of printing, and printing was started.

At the time when the printed matter was printed, the printed matter was visually observed for the inking property such as roughness and uneven density.
The amount of dampening water used was calculated based on the remaining amount in the dampening solution tank before and after printing.

[0026]

[Table 3]

[0027]

An object of the present invention is to improve the emulsification balance of ink on a printing press of a keyless rotary press, obtain a stable printed product, and further reduce the amount of dampening water used.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mitsunobu Miyasaka 339-2 Okubo Ryokeya, Uraku-shi, Saitama Mates Urawa 104 (72) Inventor Shinichi Sakamoto 3-7-8 Suehiro, Okegawa-shi, Saitama F-term ( Reference) 4J039 AB04 AB06 AD18 AE02 AE06 AF01 BA04 BA11 BE01 BE12 CA06 EA44 EA48 GA02

Claims (3)

[Claims] 1. A printing ink composition comprising 5 to 30% by weight of water particles having a particle size of 2 μm to 10 μm. 2. The printing ink composition according to claim 1, wherein the printing ink composition is for a keyless newspaper offset. 3. The printing ink composition according to claim 1, wherein the resin component has a molecular weight of 50,000 to 120,000 and an acid value of 2
The printing ink composition according to claim 1, wherein the composition comprises a rosin-modified phenol resin having a rosin content of 5 or less.