JPH02269779A - Lithographic ink - Google Patents

Abstract

PURPOSE:To decrease the piling of paper powder, etc., on a blanket without degrading the printability of a lithographic ink by compounding a specified amt. of a diethylene glycol ether into the ink. CONSTITUTION:A diethylene glycol ether, such as diethylene glycol methyl ether and diethylene glycol monobutyl ether, is compounded in an amt. of 0.5-15wt.% into a lithographic ink comprising a resin (e.g. rosin-modified phenol resin), a solvent (e.g. butyl cellosolve), a pigment, etc. The resulting ink reduces the piling of paper powder on a blanket during printing even when a low grade paper is used, thus decreasing the frequency of washing the blanket and improving the productivity in the printing.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a lithographic printing ink that can reduce piling of paper powder and the like onto a blanket. be.

(Prior art) Lithographic printing is a printing method in which printing ink is applied using a printing plate that has an oil-sensitive surface in the area corresponding to the seven image areas and a hydrophilic area in the area corresponding to the non-image area. During printing, dampening water is first supplied to the plate surface by a wet roller, and then lithographic printing ink is supplied by an ink roller. The need to use dampening water to form non-image areas is a major difference between lithographic printing and other printing methods such as gravure printing, screen printing, and letterpress printing. Various printing problems may arise due to the need to use . For example, there are problems caused by using dampening water such as background stains, floating stains, peeling of rollers, and entanglement of swimwear rollers.In addition, when using low-quality paper, paper powder may be mixed with lithographic printing ink. Another problem is that it tends to pile up on the blanket. The paper used for lithographic printing has various fillers in the valve.

It is produced through paper making and calendering processes after adding size and beating, and the surface size is adjusted during this process to adjust the paper's oil absorption, oil resistance, smoothness, surface strength, ink receptivity, etc. There are many things that are true.

Although it is made with water resistance in mind, depending on the type of paper, the surface strength of the paper weakens during the process of contact with dampening water during printing, and due to the strong adhesiveness of lithographic printing ink, it may be difficult to make a blanket. In some cases, piling was more likely to occur.

The methods that have been used in the past to reduce piles of paper dust on blankets include:

■Lower the tack of lithographic printing ink. ■Lower the tack of emulsified ink by increasing the landing rate during printing.

Wash away piled paper powder. ■Thickening of the lithographic printing ink has been attempted, but this has had little effect on some designs.

If paper dust piles up on the blanket and the extent of the pile becomes severe, not only will part of the image area on the printing surface be missing, resulting in a serious deterioration in the quality of the printed matter, but also from the viewpoint of maintenance of the blanket, it may shorten its lifespan, etc. There was also a deterioration in costs. In order to avoid such inconveniences, conventionally, when the quality of printed matter is affected by piled paper powder, printing must be stopped and the blanket must be washed.This is especially true in off-wheel printing. , increase in paper waste,
This becomes a serious factor such as a decrease in productivity. Therefore, there has been a need for a lithographic printing ink that can reduce piling of paper dust.

(Problems to be Solved by the Invention) The present invention is intended to solve the above-mentioned problems, and it is possible to prevent paper powder from being piled into a blanket even when printing paper of low quality is used without impairing printability. It is intended to provide a lithographic printing ink that can be used in a small amount.

[Structure of the invention]

(Means for Solving the Problems) The present invention relates to a lithographic printing ink characterized by containing diethylene glycol ethers in an amount of 0.5% to 15% by weight.

In the present invention, the lithographic printing ink refers to printing inks of oxidative polymerization type, heat set type, ultraviolet curing type, etc., and resins used in the ink include rosin-modified phenol resin, petroleum resin, rosin-modified maleic acid resin, etc. resins, linseed oil rosin phenolic resins, acrylic acid-modified rosin phenolic resins, etc. Other drying oils, monomers, solvents,
All types of auxiliary agents, pigments, etc. can be applied, and all conventionally known lithographic printing inks can be applied to the present invention.

In the present invention, diethylene glycol ethers refer to etherified derivatives of diethylene glycol such as diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol monobenzoyl ether, and diethylene glycol monobenzoyl ether.

The content of diethylene glycol ethers in the lithographic printing ink varies depending on the type thereof, but is in the range of 0.5% to 15% by weight, preferably 0.5% to 10% by weight. If the content is less than 0.5% by weight, it will not be possible to sufficiently reduce piling of paper powder into the blanket, and if it exceeds 15% by weight, the solubility of the lithographic printing ink will deteriorate and it will not be possible to use it in the lithographic printing ink. This is not preferable because it may cause precipitation of the resin present in the process. In addition, depending on the type of diethylene glycol ether, for example, diethylene glycol monobenzoyl ether, 15
When using an ink having a high boiling point of 3 to 154'C/12 mmHg, if too much is contained, the drying properties of the lithographic printing ink may deteriorate.

In addition, when adding diethylene glycol ethers to the lithographic printing ink, it may be added in a predetermined amount to the lithographic printing ink as a product, or it may be added at the time of manufacturing the lithographic printing ink, but when adding it at the time of manufacturing, flushing In the case of a lithographic printing ink that undergoes a process, it is preferable to add it in a process after the flushing process is completed, so that the desired effect of the present invention can be fully exerted. This is because diethylene glycol ethers are water-soluble and may flow out during the flushing process.

The reason why diethylene glycol ethers in the present invention reduce piling of paper powder onto the blanket is that diethylene glycol ethers are soluble in water and organic solvents, and are also compatible to some extent with resins used in lithographic printing inks. I think it's because there is. During the process in which lithographic printing paper comes into contact with dampening water during printing, the hydrophilic coating layer and paper dust such as fibers on the surface of the paper tend to come off.

The paper powder is piled onto the blanket, but because the lithographic printing ink contains diethylene glycol ethers, which are hydrophilic and lipophilic solvents, the separated paper powder is easily accepted by the lithographic printing ink. I think this is because it transfers to the printing paper along with the lithographic printing ink without piling onto the blanket.

There are other hydrophilic and lipophilic solvents such as butyl cellosolve, chloride, and til cellosolve, but all of them have too low boiling points and are not suitable for use in lithographic printing inks.

〔effect〕

The lithographic ink used in the present invention can suppress piling of paper dust onto the blanket even when printing paper of poor quality is used. Therefore, the number of times the blanket is washed during printing can be reduced, contributing to a reduction in the amount of paper waste generated and an improvement in productivity.

(Example and comparative example) The present invention will be specifically explained below using Examples.

Note that the rosin-modified phenolic resin varnish in Table 1 was obtained by a conventional method using the following formulation, and the No. 3 solvent was a solvent manufactured by Nippon Oil Company (trade name), Lionol Blue FG73.
30 is a pigment (trade name) manufactured by Toyo Ink.

Rosin Phenol Varnish (Unit: Weight %) Tamanol 356 50.0 (Rosin modified phenol, trade name manufactured by Arayo Kagaku Co., Ltd.) Linseed oil
No. 15.03 Solvent
35.0 total
Inks of 100.0 Comparative Examples and Examples were prepared in a conventional manner according to the formulations shown in Table 1, and the tack was adjusted to a range of 5.0 to 6.0.

A printing test was conducted under the following conditions using the inks of Comparative Examples and Examples of the above formulations, and the state of piling on the blanket when printing 10,000 copies was visually determined.

Conditions for use Printing machine: Mitsubishi Lithopia L-400 (Mitsubishi Heavy Industries ■trade name) Paper: Henry Yo 1-P (Daisyowa Seisakusho ■trade name) Dampening water: 1% of LRH (Toyo Ink Manufacturing ■trade name) Tap aqueous solution printing speed: 400 rpm Temperature and humidity: 20-21°C, 40-50% RH Blanket: Meiji MXA (Meiji Rubber ■ trade name) As a result, no piling was observed when the inks of each example were used. On the other hand, in Comparative Example 1, the piling was noticeable and the printing area was raised, in Comparative Example 2, there was little piling but the ink tank rose on the printing press and there was a bulge, and in Comparative Example 3, there was a rise in the printing area. Piling was observed, albeit slightly.

Furthermore, in Comparative Example 4, although there was no piling, the drying of the printed matter was poor.

In the above examples and comparative examples, Neoresin 540 (petroleum resin manufactured by Nippon Petrochemical Co., Ltd., trade name) was used in place of Tamanol 356 in the rosin-modified phenolic resin varnish formulation.
When a red ink was prepared in the same manner except that the same method was used and a printing test was carried out, the same results were obtained.

Margin below

Claims (1)

[Claims] 1. 0.5% by weight of diethylene glycol ethers
A lithographic printing ink characterized by containing 15% by weight.