JPH0925443A - Ink composition for offset printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink composition capable of widening the allowable ranges of printing conditions such as the width of suitable wetting water supplying range, improving the printing aptitude and reducing the stains, etc., on the printing surface by blending a dimer diol at a specific ratio to improve an emulsifying aptitude. SOLUTION: This ink composition for an offset printing contains 0.01-10wt.% dimer diol. As the dimer diol, it is preferable to use a mixture containing a 36C dimer diol obtained by reducing a dimer acid obtained by the dimerization of an 8C unsaturated fatty acid, as a major component. The objective composition is preferably obtained by blending 20-50wt.% binder resin such as an alkyd resin, etc., 0-30wt.% plant oil such as a linseed oil, etc., 2-60wt.% pigment, 10-60wt.% solvent such as an aromatic hydrocarbon, etc., and 0.05-2wt.% dimer diol. There is no limitation in the method of adding the dimer diol. But, when preparing the printing ink base for the offset printing and conducting a flushing of substituting water in the cake for an oily vehicle, it is preferable to add dimer diol after the above addition operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to improve the printability by widening the permissible range of printing conditions such as water width (width of appropriate dampening water supply) in offset printing, and to obtain a high-definition printed matter. Offset printing ink composition.

[0002]

2. Description of the Related Art In offset printing, an offset printing ink composition is supplied to a printing plate together with a fountain solution. Since the repulsive force against dampening water is different between the imaged area and the non-imaged area on the plate surface, a difference occurs in the ink receptivity of the offset printing ink composition to form an image. If the offset printing ink composition is not in an appropriate emulsified state, the paper surface may become dirty due to the offset printing ink composition adhering to the non-image area, and the image density may decrease due to improper inking of the image area. Harm appears. In addition to this, poor emulsification suitability causes troubles such as piling, roller slip, and misting. In order to obtain a highly vivid printed matter without causing such a printing trouble, a technique for controlling the emulsified state of the offset printing ink composition with a fountain solution in a delicate balance is required. On the other hand, due to the increase in printing speed in recent years, the shear stress applied to the emulsified ink on the blanket cylinder and the plate surface has become extremely high. However, even in the same printing machine, the stress in the ink reservoir is low. Since the emulsified state of the offset printing ink composition is also affected by the strength of shear stress, it is necessary to dynamically set the emulsified state to a proper value in each part of the printing machine where the stress thus changes to various levels. It's getting harder and harder.

In order to cope with this, an alkylene oxide adduct of rosin is used in the conventional method (Japanese Patent Laid-Open No. 6-234)
950), a compound having an unsubstituted or substituted alkylene oxide unit having a total number of carbon atoms of 4 or more and an average molecular weight of 400 or more is used (JP-A-1-95).
173), having an alkylene oxide unit, HL
A compound having a B value of 3 to 13 is used (JP-A-61-138).
No. 677) and the like, a method for adjusting the emulsification is disclosed. However, although these methods show some effects, they cannot cope with a wide range of changes in shear stress. As mentioned above, the emulsification of the offset printing ink composition needs to be suppressed or, conversely, accelerated in each part of the printing machine. However, in the conventional method, the offset printing ink composition and the dampening water are separated in the ink reservoir by the material added to suppress the emulsification rate of the offset printing ink composition on the plate surface, or conversely There is often a problem that a material for assisting the internal emulsification accelerates the emulsification of the offset printing ink composition on the plate surface more than necessary.

[0004]

As described above, in the field of offset printing, materials and techniques satisfying both requirements at the same time have been earnestly desired.

The present invention has been made in order to solve such problems of the prior art, and is suitable for emulsification of an offset printing ink composition (contradicting requirements for emulsification of an offset printing ink composition on a printing press, namely, In order to suppress emulsification on the plate surface where high shear stress is applied to the ink, but to keep the dampening water from separating in the ink reservoir with low stress) An object of the present invention is to provide an offset printing ink composition capable of improving printing suitability by widening an allowable range of printing conditions such as width and reducing stains and printing troubles on a printing surface.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that a method of incorporating a dimer diol into an offset printing ink composition is effective, and have made the present invention It came to completion.

That is, the present invention relates to an offset printing ink composition characterized in that the dimer diol is contained in the offset printing ink composition in the range of 0.01 to 10% by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The dimer diol used in the present invention means a dimer acid which is a dimer of an unsaturated higher fatty acid and can be obtained by reducing a so-called dimer acid. Examples of the unsaturated higher fatty acid mainly include those having 16 to 20 carbon atoms. Among them, a preferred unsaturated higher fatty acid has a carbon number of 18, and a dimer diol containing a component having a carbon number of 36, which is obtained from this, as a main component can be preferably used. Depending on the reaction conditions of the thermal polymerization, these are a mixture of various structures, and to give a few examples,

[0009]

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Some have an alicyclic structure and some do not. Any of these may be used in the present invention, or a mixture thereof may be used.

The amount of the dimer diol used in the present invention is 0.01 to 10% by weight in the offset printing ink composition, preferably 0.05 to 10 in view of printability and cost.
It is preferably in the range of 2% by weight. If the amount of dimer diol used is less than the above range, the desired effect cannot be sufficiently obtained. On the other hand, even if it exceeds the above range, the effect is not further improved, resulting in unnecessary cost increase. However, the effect of adding the dimer diol varies depending on the resin, pigment, solvent or other additive used in the offset printing ink composition, printing conditions, etc., and the optimum amount is determined in each case. Is preferred.

The offset printing ink composition for blending the dimer diol according to the present invention is a known binder resin such as various alkyd resins, phenol resins, petroleum resins, rosin ester resins, polyester resins, or modified products thereof. Vegetable oil such as linseed oil, tung oil, soybean oil,
Normal paraffin, isoparaffin, aromatic hydrocarbon, a solvent such as naphthene or a mixture thereof, a pigment such as an organic or inorganic pigment is dispersed, if necessary, a pigment dispersant, a dryer, a gelling agent, Additives such as a drying delay agent and an antioxidant may be appropriately contained.

The method for adding the dimer diol according to the present invention to the offset printing ink composition is not particularly limited,
It can be carried out by any of a method of mixing and using during the production of varnish, a method of mixing and using during the production of offset printing ink base, and a method of adding during the production of the offset printing ink composition from the base. However, when the water in the cake is replaced with the oily vehicle when the offset printing ink base is prepared, that is, when so-called flushing is performed, it is preferable to add the dimer diol after such an operation.

The preferred range of each component in the offset printing ink composition of the present invention is shown below.

Component Weight% Binder resin 20-50 Vegetable oil 0-30 Pigment 2-60 Solvent 10-60 Dimer diol 0.01-10 (preferably 0.05-2) Offset printing with addition of the dimer diol according to the present invention By using the ink composition, it is possible to obtain a printed matter with less stain on the paper surface even when the amount of change in the dampening water supplied to the plate surface during printing is wide. Although this mechanism is not always clear, it is confirmed that the effect of maintaining the emulsification in the ink reservoir is maintained so that the dampening water does not separate in spite of suppressing the emulsification on the plate surface to which high shear stress is applied. It is considered that the dimer diol has a unique action as a high molecular weight surfactant.

[0016]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples without departing from the gist and the scope of application thereof. In the following, "part" means part by weight.

[Manufacture of varnish for offset printing ink]
A four-necked flask equipped with a condenser, a thermometer, and a stirrer contained 40 parts of linseed oil, 186 parts of rosin-modified phenolic resin (TESPOL 1365 manufactured by Hitachi Chemical Polymer Co., Ltd.), and AF-7 solvent (Japan). 174 parts of Petrochemical Co., Ltd. was charged, the temperature was raised to 190 ° C., and the mixture was stirred at the same temperature for 60 minutes to obtain a varnish for offset printing ink.

[Production of offset printing ink composition] 73 parts of varnish for offset printing ink, 17 parts of red pigment (Carmine 6B, manufactured by Sumika Color Co., Ltd.), 3 parts of polyethylene wax compound (manufactured by Shamrock) , And AF-7 solvent 7 parts were added and the mixture was kneaded with a three-roll mill to obtain a composition for offset printing ink.

Examples 1 to 6 Dimer diol (Toagosei Co., Ltd.) was added to the ink base for the offset printing ink so that the compounding ratio was as shown in Table 1.
Manufactured by HP-1000) was added and mixed, and then the mixture was kneaded again with three rolls to obtain offset printing ink compositions of Examples 1 to 6.

Comparative Example 1 An offset printing ink composition was used as it was without adding dimer diol to the ink base.

Comparative Examples 2 and 3 Hexamethylene glycol (Comparative Example 2) or 1,4-dimethylolcyclohexane 6 mol adduct of propylene oxide was added to the ink base for the offset printing ink so that the blending ratio was as shown in Table 1. Was added and mixed, and then the mixture was kneaded again with three rolls to obtain offset printing ink compositions of Comparative Examples 2 and 3.

[0022]

[Table 1]

[Performance Evaluation Test] Table 2 shows the performance evaluation results of the offset printing ink compositions of Examples 1 to 6 and Comparative Examples 1 to 3. The printability was examined by actually printing with an offset printing machine manufactured by Mitsubishi Heavy Industries, Ltd. This printing machine has a mechanism in which the dampening water is supplied by a device called Smith Damper and the supplied water amount is proportionally changed by changing the voltage applied there. Contamination of the printing paper surface was examined when this voltage was changed by −10 V (reduction of the supply water amount) and +10 V (increase of the supply water amount) with respect to the standard supply water amount (voltage 60 V). The fountain solution used contained SLH (manufactured by Sakata Inx Co., Ltd.) as an additive. The state where there is no stain or water trace on the paper surface is represented by 3, the state where stain or density unevenness on the non-image area, or water trace appears, is represented by 1, and the middle thereof is represented by 2.

[0024]

[Table 2]

As can be seen from Examples 1 to 6, the inclusion of dimer diol broadened the range of the amount of water supply that was able to obtain printed matter with less paper stains. On the other hand, in Comparative Examples 1 to 3, the water width was narrow and the paper surface was easily soiled. In Examples 1 to 6, separation of dampening water in the ink reservoir was not recognized.

[0026]

As described above, by using the offset printing ink composition to which the dimer diol is added in the offset printing, the emulsification is suppressed on the plate surface to which a high shear stress is applied, and the dampening is performed in the ink reservoir having a low stress. It became possible to maintain the emulsification so that the water did not separate. As a result, the emulsification suitability of the ink on the printing machine was improved, the permissible range of printing conditions such as the water width was widened, the printability was improved, and stains on the printing surface and printing troubles could be reduced.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yanagihara 1-23-37 Edobori, Nishi-ku, Osaka City Sakata Inx Co., Ltd. (72) Hideki Kinoshita 1-23-37 Edobori, Nishi-ku, Osaka City Sakata Inks Within

Claims (1)

[Claims] 1. An offset printing ink composition, wherein the offset printing ink composition contains dimer diol in a range of 0.01 to 10% by weight.