JPH0830160B2 - Anti-setoff agent and offset printing ink containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an anti-setoff agent and an offset printing ink containing the same.

(Prior Art) Normally, it takes several hours for an offset printing ink to dry, and therefore the coating surface immediately after printing has extremely high adhesion. Therefore, in sheet-fed offset printing, in which printed sheets are sequentially stacked in the delivery section of the printing machine,
A phenomenon called "set-off" occurs in which the undried ink is then printed and adheres to the back side of the stacked sheets.

Conventionally, in order to prevent this set-off, a powder containing industrial starch as the main component is sprinkled on the printing surface immediately after printing, and a void is created between the stacked sheets to prevent ink from adhering. The spray method is used.

In addition, there is also known a method of directly adding industrial starch to the offset printing ink to prevent set-off.

(Problems to be Solved by the Invention) In the above-mentioned powder spray method, the working environment deteriorates,
There were drawbacks such as accelerated wear of the printing press and deterioration of the quality of printed materials.

In addition, in the method of adding directly to the ink for offset printing, since the starch has a high hydrophilicity, the ink easily absorbs dampening water, greatly reduces the emulsification resistance of the ink, and changes the fluidity of the ink greatly. However, there are drawbacks such as poor transferability of ink from the ink roller to the printing plate in the printing press, printing plate to blanket, and blanket to printing medium, and poor dot reproducibility of the printed matter. Furthermore, the expected outflow prevention effect cannot be obtained because the starch flows out into the dampening water from the ink, and the "plate residue" or "blank residue" in which the starch gradually accumulates on the printing plate surface or blanket. There is a drawback that a so-called phenomenon occurs and clear printed matter cannot be obtained.

(Means for Solving the Problems) The present invention is to heat impregnate starch granules with a resin varnish obtained by melt-mixing at least one resin selected from natural resins or processed resins thereof and synthetic resins with a drying oil and a solvent, or a drying oil. An anti-setoff agent which is obtained at most and an ink for offset printing characterized by containing the same, wherein the settling is prevented by subjecting the starch granules to the above treatment,
Moreover, it was possible to obtain an offset printing ink with improved "print residue" and "blank residue".

The present invention heats a starch granule and a resin varnish and / or a drying oil, preferably under mechanical agitation, to impregnate the starch granule with the resin varnish and the drying oil to make the starch particle hydrophobic, An anti-setoff agent having improved dispersibility in ink can be obtained.

In the present invention, the starch granules include various industrial starch granules,
For example, starch obtained from corn, rice, sweet potato, potato, tapioca, sago and the like can be used. As long as the performance of the anti-setoff agent of the present invention is not impaired, various industrially modified starches or modified starches such as etherified starch, esterified starch, crosslinked starch, starch graft copolymer and the like may be used.

The particle size of starch is not particularly limited, but it is desirable to include a large amount of starch having a particle size of about 5 to 15 μm, such as rice starch and corn starch. If the number of particles having a particle size smaller than this is increased, less starch particles are exposed from the surface of the printing ink film, and the offset prevention effect tends to be reduced. If the particle size is larger than this, the gloss of the surface of the printing ink film after drying will decrease and the quality of the printed matter will tend to deteriorate.
Generally, corn starch has a particle size of about 2 to 30 μm. Therefore, industrially classify these starches and use classified starch in which most of them have a particle size of about 5 to 15 μm. It is preferable to use silicone for convenience of classification.

Further, when the anti-setoff agent obtained by the present invention is added to the printing ink and the amount of starch in the printing ink is less than 0.01% by weight, the anti-setoff effect tends to decrease, and the amount is more than 3.0% by weight. As a result, the gloss of the surface of the printing ink film after drying decreases and the quality of the printed matter tends to deteriorate.
It is preferably 0.1 to 2.0% by weight.

In the present invention, as the drying oil to be impregnated into starch granules, natural or synthetic drying oils such as linseed oil, tung oil, eno oil, soybean oil, fish oil, styrene oil, maleated oil, and polymers thereof are used. Of these, linseed oil and tung oil, which are mainly used for oxidation-polymerization type dry ink, are preferable.

Similarly, as the resin varnish for impregnating starch granules in the present invention, for example, natural and processed resins such as rosin, copal, dammar, hardened rosin and rosin ester, phenol resin, rosin-modified phenol resin, maleic acid resin, alkyd resin. , A petroleum-based resin, a vinyl-based resin, an acrylic resin, a polyamide resin, an epoxy resin, an aminoalkyd resin, and a drying oil or solvent generally used for ink are melt-mixed.

As the solvent used for dissolving these natural resins and synthetic resins, various organic solvents such as the above-mentioned drying oil and petroleum solvent conventionally used for printing ink can be used.

The above examples are for explaining the present invention,
Drying oils, resins, and solvents other than the above, which have the same function as above, are naturally included in the present invention.

In the present invention, an effective anti-setoff agent can be obtained by heating and impregnating starch granules using the above-mentioned drying oil or resin varnish. No special equipment is required for the method of heat impregnation. The amount of the drying oil and / or resin varnish necessary for impregnating the starch granules should be a sufficient amount to make the starch granules hydrophobic, and preferably 300 parts by weight per 100 parts of the starch granules. The above drying oil and / or resin varnish may be used and there is no particular upper limit. The starch particles may be in the form of paste or powder depending on the amount and type of the drying oil and / or the resin varnish, but in the present invention, any state may be used. There is no problem as long as the heating condition is 80 ° C. or higher, but the target starch granules can be properly treated by heating at 150 to 220 ° C. for 5 to 30 minutes. At this time, in order to uniformly impregnate the starch granules with the drying oil and / or the resin varnish, stirring during heating is more effective. The treated starch granules thus obtained may be added as they are to the ink as a set-off preventing agent.
Even if added to the ink in a compound state using varnish, its effect does not change.

When this anti-setoff agent is added to the ink for offset printing, the components of the printing ink may be the same as those in the prior art. For example, the colorant constituting the printing ink of the present invention is a pigment or dye used in a conventional printing ink, and any conventionally known pigment or dye can be used as it is as a colorant of the printing ink of the present invention. It is a thing.

The amount of the ink used may be the same as that of the conventionally known printing ink. For example, in 100 parts by weight of the printing ink, for example, about 10 to 4
The proportion of 0 parts by weight is common. Further, as the varnish constituting the printing ink of the present invention, a conventionally known varnish for printing ink may be selected according to its purpose, and the usage amount thereof is the same as in the conventional one, for example, about 5 parts in 100 parts by weight of the printing ink.
A proportion of 0 to 80 parts by weight is common.

As described above, the offset printing ink of the present invention comprises a colorant, a varnish, and a set-off preventing agent as essential components, and other ink solvents, dryers, and other conventionally known additives are used in the offset printing ink of the present invention. Either can be used.

Further, the anti-setoff agent, which is a main part of the present invention, has the same effect as that of the present invention when added to a waterless planographic ink for sheet or an ink for letterpress printing.

(Operation) As described above, according to the present invention, by adding the treated starch granules using the transfer oil and / or the resin varnish to the offset printing ink, the set-off prevention effect is maintained.
It was possible to obtain an offset printing ink with improved "print residue" and "blank residue".

Since the starch granules added to prevent set-off in the prior art tend to increase the "print residue" and "blank residue" in proportion to the increase in the amount of anti-set-off agent used, clear printed matter can be obtained. This is a significant improvement over the drawbacks such as the inability to clean the printer and the need to clean the printing press.

The present invention will be described below with reference to specific examples. In the examples, "parts" means "parts by weight" and "%" means "% by weight".

Examples 1 to 4 According to the formulations of Comparative Examples 1 to 4 in Table 1, 20 parts of each starch granule was dried with 10 parts of a drying oil or resin varnish at 180 ° C. for 30 minutes with stirring using a stirrer. I got D.
Further, untreated raw starch was designated as E.

Example 5 1) Preparation of base ink A base ink having the following formulation was prepared by a conventional method. Tack value of the obtained base ink (Incometer 400rp
m.30 ℃, 1 minute) is 9.0, flow value (spread meter 25
The temperature was 18.0.

Prescription of base ink Phthalocyanine blue 18.0 parts (Toyo Ink Mfg. Co., Ltd., indigo pigment) Varnish B 68.0 parts Drying accelerator 2.0 parts Petroleum solvent (boiling point 260-280 ° C) 12.0 parts Note) Varnish B is Tamanol 361 (Arakawa) Chemical Industry Co., Ltd. rosin-modified phenolic resin) 50.0 parts, linseed oil 20.0 parts,
16% of petroleum solvent (boiling point 160-280 ℃) 30.0 parts in a flask
Obtained by heating and melting at 0 ° C.

2) Preparation of test inks The set-off preventive agents A to D of the examples were added as starch granules to the above base ink immediately after their preparation, and E was added to each of the test inks at 0.5% without treatment. Adjusted E. The addition was performed using three rolls in a state in which no excessive pressure was applied, that is, in the so-called "clear state". Even in the plain state, each anti-setoff agent could be easily and uniformly mixed with the base ink. For comparison, the above base ink to which the anti-setoff agent was not added was used as test ink I.

3) Test Printing the obtained test inks A to E and I on SK coated paper (Sanyo Kokusaku Pulp Tab) with a Heidelberg GTO offset two-color printing machine to obtain corresponding prints A to E and I, respectively. It was

At the time of printing the above 5,000 printed matter, the effect of preventing set-off from the state of the back side of the printed matter, the plate residue from the state on the plate surface, and the blank residue from the state of the blanket surface were evaluated. The judgment was made visually. The test results are shown in Table 2.

It can be seen that the ink containing the anti-setoff agent of the present invention is excellent in the effect of preventing set-off, the effect of preventing plate residue, and the effect of preventing blank residue.

Claims (4)

[Claims] 1. A settling preventive agent comprising a resin varnish prepared by melt-mixing at least one resin selected from natural resins or processed resins thereof and synthetic resins with a drying oil and a solvent, or by impregnating starch oil with the drying oil. 2. The anti-setoff agent according to claim 1, wherein the starch granules are one or two selected from rice starch and corn starch. 3. The anti-setoff agent according to claim 1, wherein the starch granules are starch granules treated with silicone. 4. An offset printing ink containing the anti-setoff agent according to claim 1.