JPS59196374A - Dry lithographic ink composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. having excellent transferability and resistance to scumming, containing an alpha-olefin solvent having a specified boiling point. CONSTITUTION:At least 5wt% alpha-olefin solvent having a b.p. of 200 deg.C or higher is added to a dry lithographic ink obtd. by adding a pigment, an extender pigment, etc. to varnish consisting of a (semi)drying oil such as linseed oil or soybean oil and a vehicle such as a phenolic resin or an alkyd resin and kneading them. EFFECT:A glossy print can be obtd. without causing piling.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a dry lithographic ink composition having anti-smudge resistance and excellent printability.

<Prior art> Currently, planographic printing utilizes the property that oil-based ink and dampening water repel each other, and the dampening water and dampening water are applied to a printing plate consisting of an oleophilic image area and a hydrophilic non-image area. Printed matter is obtained by applying oil-based ink and transferring the oil-based ink onto a printing medium.

However, in such planographic printing methods that use dampening water, it is difficult to control the dampening water to prevent ink from adhering to non-print areas, and it is also difficult to control the dampening water to prevent ink from adhering to non-printing areas. One of the major technical hurdles is the use of

Therefore, various attempts have been made to perform dry lithographic printing using lithographic printing plates that do not require dampening water. The newest and most practical method of dry lithographic printing is the method of printing using a dry lithographic printing plate that has a non-stick thin film such as silicone rubber on the non-image area. It has been reported that printing can be performed with regular oil-based ink without the need for dampening water.

However, in practice, it has been found that printing using conventional oil-based inks is undesirable because of its inadequate printability, resulting in scumming.

What is the phenomenon of scumming in dry lithographic printing?

During printing, the temperature of the printing plate surface rises due to friction between the printing press's drive unit and rollers, which reduces the cohesive force of the ink itself, causing ink to adhere to non-image areas that should normally be ink repellent. It is something to do.

Therefore, as a method to improve these problems, for example, Japanese Patent Publication No. 48-19382 proposes a method of preventing ink from adhering to non-image areas by imparting a significantly high cohesive force to the ink.

On the other hand, Japanese Patent Publication No. 50-11287 describes a method of adding organopolysiloxane to ink to prevent ink from adhering to non-image areas.
4 proposes a method using silicone-modified alkyd resin.

However, when the cohesive force of the former type of ink is increased too much, it causes poor transfer between rollers and poor adhesion to the blanket, as well as poor leveling of the ink on the printing medium and poor gloss. Was.

In addition to the disadvantages of the former ink, the latter type of ink also reduces the surface energy of the printed ink film on the printing substrate, resulting in ink build-up (trapping) in multicolor overprint printing. ), and when the amount added is too large, the transferability between rollers is poor, and in particular, copper-plated rollers are prone to roller flaking.

Furthermore, among conventional inks, especially the former type of ink, staining of non-image areas is relatively difficult to occur when the plate surface temperature is low at the start of printing.

If the plate surface temperature rises during continuous operation, or
Significant stains occur during high temperatures in the summer, and it is not suitable for the temperature, and at the same time, due to its high tack, it is prone to paper dust and
The ink had an extremely narrow range of suitability, as it caused piling on the blanket due to pinking of the paper coating layer.

If n-paraffinic solvents are still used.

Although suitability for piling etc. is improved, the balance of pour point, boiling point, etc. is poor, and low boiling point solvents have poor on-machine stability, while high boiling point solvents have improved on-machine stability.

The ink characteristics have a drawback of having strong temperature dependence.

<Purpose of the invention> The object of the present invention is to improve printability, especially transferability.

The gloss of the printed matter is better, and there is no occurrence of highlighting etc.
An object of the present invention is to provide an excellent ink composition for dry planography.

<Structure of the Invention> In other words, the present invention is based on a conventional lithographic printing ink composition containing 5% by weight of an α-olefin component having a boiling point of 200°C or higher.
This invention relates to a dry lithographic ink composition characterized by containing the above.

The high-boiling point solvent specified in the present invention has excellent solvent release properties with the vehicle resin used in the ink, and has a strong affinity with silicone rubber, etc., which is an ink repellent layer, so that it is compatible with the dry lithographic plate and the ink. At the time of contact, a kind of solvent thin film is formed between the ink repellent layer and the ink film, and the ink film can be peeled off without adhering ink to the silicone rubber layer, which is the non-image area.

In this way, excellent suitability for dry lithographic printing can be obtained by containing a specific high-boiling point α-olefin, and the ink's original properties can be improved by increasing the cohesive force of the ink more than necessary or by adding additives. It is possible to achieve the original purpose without impairing the properties of the product.

The α-olefin solvent has a carbon number of Cto''-Cs.

% KCl4 to C2o are preferably used.

The amount of a-olefin solvent contained in the ink is determined by the ink material used, especially the type and molecular weight of the resin, and the type and amount of drying oil and semi-drying oil, but it is 5% by weight based on the total amount of the ink composition. It is necessary to contain more than this; if it is less than that, sufficient suitability for dry lithography cannot be obtained.

In the ink composition used here, vehicle resins that have been conventionally used for lithographic printing inks can be used. For example, phenol! oil, gin-modified phenolic resin, alkyd resin, rosin ester resin, petroleum resin, maleic acid resin, etc. In addition, drying oils and semi-drying oils include linseed oil, tung oil, soybean oil, safflower oil,
Castor oil etc. can be used.

The present invention is characterized by the use of α-olefin as a solvent;
A petroleum solvent with a high boiling point of 350° C. can be used in combination. Particularly preferred is the combination of paraffinic and inoparaffinic solvents.

When producing ink, add a coloring agent (1) to the varnish described above, knead it using a conventional method, add wax, dryer, cornstarch, etc. as necessary,
Ink can be manufactured.

Examples will be described below, but the present invention is not limited thereto.

Example 1. Comparative Example 1 Ink A with the following composition and using α-olefin (Daikiren 168. manufactured by Mitsubishi Kasei (To) 3) as a solvent,
Ink B (comparative example) was prepared using an ink solvent (Nisseki No. 5 Solvent, Nippon Oil ■), which is commonly used as an ink solvent.

Ink composition>

Carbon Black 18.0 parts Rosin Modified Fuegil 4'DJ Fat Fes (I)" 5
4.0 parts rosin modified phenolic resin gel varnish (u)”
22.5 parts alkaline blue toner
50 parts Naphthenic acid cobalt salt 0.3
parts (metal concentration 60%) Manganese naphthenate 0.2 parts Composition of rosin-modified phenolic resin varnish (I) Rosin-modified phenolic resin 630 parts Polymerized linseed oil
660 parts high boiling point solvent
64.0 parts Total 1000 parts Composition of Tsukasa rosin-modified phenolic resin gel varnish (II) Rosin-modified phenolic resin 58.0 parts Polymerized linseed oil 232 parts Aluminum octoate 2. Os High boiling point solvent 38.0 parts total 1
000 parts The following solvent was used as a high boiling point solvent in the varnish having the above composition.

Ink A: Dialen 168 Ink No. 81855 Solvent The scumming temperature of the inks A and B above, which is a measure of scumming resistance, was measured by the following method.

Method for evaluating background smudge resistance (measuring the temperature at which background smudge occurs) A dry lithographic plate with a non-adhesive layer made of silicone rubber was attached to a printing machine that had been improved so that the temperature of the plate surface could be raised by passing hot water through the plate cylinder. , printing was carried out while raising the temperature of the two plate surfaces without supplying dampening water, and the plate surface temperature at which scumming occurred on the printed matter at a constant solid density was taken as the scumming generation temperature.

Ink with a high scumming temperature is less likely to cause scumming even in practical printing.

As a result, the scumming temperature of ink A was 68°C.

The temperature of Ink B was 65°C, and it was found that Ink A of the present invention was less likely to cause scumming.

Next, the fluidity (flow value) of these inks was measured with a spread meter, and the tank value was measured with an incometer, and the following results were obtained.

(Measurement temperature: 30° C.) As a result, it can be seen that ink A of the present invention has a lower stickiness value than conventional ink B, and is easy to handle with an ink spatula.

Next, each of these inks was printed using a dry planographic printing plate having a non-adhesive layer made of silicone rubber on a Komori Sprint planographic printing machine without supplying dampening water to the plate surface.

As a result, all inks had excellent pressure point responsiveness, but the prints made with ink A had excellent gloss and texture.
There was no occurrence of piles or the like on the plate or blanket.

However, ink B caused piling due to paper dust on the blanket, and as the number of sheets printed increased, poor inking caused by piling occurred, making it impossible to obtain satisfactory printed matter. Therefore, the plankette and plate were washed and printed again, but after about 500 sheets, defective inking due to quilling occurred.

Example 2. Comparative Example 2 Inks were prepared using the varnish and gel varnish compositions of Example 1, but with different high boiling point solvents.

Ink composition> Phthalocyanine blue 18.0 parts Rosin-modified phenolic resin varnish (J) 57.0 parts Rosin-modified phenolic resin gel varnish (II) 24
．． 5 parts Cobalt naphdate 05 parts (metal concentration 6 parts) Total 1000 parts Ink C: Daikiren 168 Ink D, 1:1 mixture of Daikiren 168 and Ko P 2835 (isoparaffin-based, manufactured by Idemitsu Kosan ■) Ink E: IP2835 Ink F: Magginol 52 (manufactured by Magee Brothers Ya4) Inogi G: Dialen 168 and Maggi Tsuru 52 1:1
A mixture of Ink H: Nisseki No. 5 Rubento Ink: Ink H to which 2 parts of silicone oil (SH200 oil, 100C8, )-manufactured by Resilicone ■ was added.

The scumming temperature, tack value, and flow value of these inks 0 to 1 were measured, and the following results were obtained.

As a result, ink C using Dialene 168 alone had the lowest incometer tack, and Dialene 1 was the lowest.
Inks D and G using a mixture of 68 and other solvents
It can be seen that this is followed by a low value.

Furthermore, the inker to which silicone oil was added had poor on-machine stability on the incometer, and roller baldness occurred.

Printing was carried out with each of these inks using a dry planographic printing plate having a non-adhesive layer made of silicone rubber on a Komori Sprint planographic printing machine without supplying dampening water to the second plate surface. As a result, ink C does not cause piling or the like.

There is little transference or curling of paper, and it has excellent paper ejection properties.

The gloss of the print was also good. This tendency is good for ink C, followed by ink D and ink G. Then, in the order of Ink F, Ink Ink, and Ink H, piling on the plunket became more severe, the curl of the paper became large, and problems such as backing occurred.

It was found that the Ingye had poor stability on the machine, and it took a long time for the colorimetry to stabilize.

Claims (1)

[Claims] An ink composition for dry lithographic printing, characterized in that it contains an α-olefin solvent having a boiling point of 20 [1'C or more] in an amount of 5 weight percent or more.