JP2000007971A - Emulsion ink composition for offset printing and offset printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an emulsion ink compsn. for offset printing which can supply an appropriate amount of water to the surface of a plate by water separation of the ink compsn. itself. SOLUTION: This emulsion ink compsn. for offset printing comprises 70-40 wt.% oily component mainly composed of a coloring agent, a binder resin, and a vegetable oil and/or a mineral oil, and 30-60 wt.% aq. component mainly composed of water, and contains 0.04-3.5 wt.% higher alcohol represented by formula I and 0.04-2.1 wt.% nonionic surfactant represented by formula II in the total ink compsn. Formula I: R1-OH. Formula II: R2-O-[CH2-CH2-O]n-H. (wherein, R1 is a 6-24C hydrocarbon group, R2 is a 4-24C hydrocarbon group, (n) is 1-16, and if carbon number of R2 is (k), 1.5n<=k<=6n).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emulsion ink composition for offset printing, and an offset printing method using the same to perform printing without using a dampening solution supply device.

[0002]

2. Description of the Related Art In offset printing, an image is formed by utilizing the difference in the affinity (repulsion) of oily ink and dampening water in an image area and a non-image area on a plate surface. As a method of supplying dampening water to a printing press, a method of supplying dampening water to a plate surface or a method of supplying dampening water to a roller for conveying ink has been adopted. However, in order to obtain a printed matter with good image reproducibility without contamination by these methods,
It was necessary to control the ratio of ink and dampening water supply to be within an appropriate range, and this required skill and experience in the printing operation. In the printing industry in recent years, simplification of the printing environment and labor saving have come to the spotlight,
There is also a need to review the use of conventional dampening solution feeders that place a burden on printing operations.

As one method for this purpose, a method has been considered in which a fountain solution is previously contained in the ink in the form of an emulsion, and is separated from the roller by nip pressure or the like during printing. (Similar thinking is old, "newspaper printing" (October 31, 1980, edited and published by the Japan Newspaper Association), pages 231 to 234, etc.). This is intended to simplify the work by eliminating the need for the management and adjustment of the dampening solution as in the prior art. A particular requirement for emulsion inks for offset printing is that the separation of water must be controlled so that a sufficient amount of fountain solution is supplied to the plate. For this purpose, the emulsion ink for offset printing must cause the dampening solution to separate at the appropriate place on the printing press. The properties of water separation are closely related to the shear rate and stress applied to the ink. If the emulsion becomes unstable even at a low shear rate, separation occurs in the ink reservoir before the ink is supplied onto the roller or during the supply by the pump, so that sufficient dampening water cannot reach the plate surface. In this case, the ink also adheres to the non-image portion of the plate surface,
Dirt will occur. Conversely, if a sufficient amount of fountain solution is not separated even at a high shear rate, adverse effects such as a decrease in density due to poor ink deposition on the image area, density unevenness, and contamination of the non-image area will appear. If the proper amount of fountain solution is not separated, the image quality may be degraded due to a change in the picture area, or troubles such as piling and misting may be caused. In particular, with the recent increase in printing speed, the range of shear rate and stress applied to ink on printing presses has become wider, and emulsion inks for offset printing must be provided with water separation performance adapted to this. Must. As described above, in the case of printing with the emulsion ink for offset printing, higher-precision emulsification control is required as compared with the conventional method using a dampening solution supply device.

In order to solve this problem, for example, Japanese Unexamined Patent Publication No.
JP-A-5-5946 discloses a method using a nonionic surfactant having a specific HLB value, Japanese Patent Publication No. 55-18754.
Japanese Patent Publication No. 54-22324 discloses a method using carboxylic acid or phosphoric acid or a salt thereof and polyhydric alcohols, and Japanese Patent Publication No. Sho 54-7112 discloses a method using an amino alcohol or polyhydric alcohol. A method using a surfactant and a salt is disclosed. According to these methods, although it is possible to perform offset printing for a while without using a dampening solution supply device as in the related art, it is still satisfactory to stably obtain a printed matter having high image quality. No results were obtained. It is considered that the separation characteristics of the dampening solution as described above have not been sufficiently controlled.

[0005]

As described above, offset printing can be performed without using a dampening solution supply device.
In addition, there is a strong need for a technique relating to an emulsion ink composition for offset printing, which can obtain a printed matter with less stain and good image reproducibility.

An object of the present invention is to provide an emulsion ink composition for offset printing which has an improved water separation property and can supply an appropriate amount of water to a printing plate by water separation of the ink composition itself. It is an object of the present invention to provide an offset printing method for performing printing without using a dampening solution supply device.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a higher alcohol represented by the following general formula (1) and a non-ionic compound represented by the following general formula (2) The inventors have found that a method using a surfactant in combination is effective, and have completed the present invention.

[0008] That is, the present invention relates to an oily component containing a coloring agent, a binder resin, and a vegetable oil and / or a mineral oil as main components in an amount of 70 to 40% by weight, and an aqueous component containing water as a main component in an amount of 30 to 60% by weight. Wherein the higher alcohol represented by the following general formula (1) is added to the total ink composition in an amount of 0.
The present invention relates to an emulsion ink composition for offset printing containing from 0.4 to 3.5% by weight of a nonionic surfactant represented by the general formula (2) by 0.04 to 2.1% by weight.

R ¹ —OH (1) R ² —O— [CH ₂ —CH ₂ —O] _n —H (2) wherein R ¹ is a saturated group having 8 to 24 carbon atoms,
Alternatively, a hydrocarbon group which may contain an unsaturated bond is represented by R ²
Represents a saturated or unsaturated hydrocarbon group having 4 to 24 carbon atoms and optionally containing an unsaturated bond or an aromatic ring;
Represents an integer in the range of １６16 and k is the number of carbon atoms of R ² , and k and n satisfy the relationship of 1.5n ≦ k ≦ 6n)

Further, the present invention uses a conventional dampening solution supply apparatus such as a method of supplying a dampening solution to a plate surface and a method of supplying a dampening solution to an ink transport roller using the emulsion ink composition for offset printing. The present invention relates to an offset printing method characterized by performing printing without performing printing.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the emulsion ink composition for offset printing of the present invention will be described in detail.

The emulsion ink composition for offset printing of the present invention contains 0.04 to 3.5% by weight of a higher alcohol represented by the following general formula (1) in the total ink composition, and the general formula (2) ) Is contained in an amount of 0.04 to 2.1% by weight.

According to the emulsion ink composition for offset printing of the present invention, emulsification is stabilized under a low shear rate such as during ink supply or feeding by a pump due to the specific composition, and water separation does not occur. The emulsification is destabilized at appropriate locations under high shearing speeds, such as on the plate surface, causing water separation, supplying an appropriate amount of dampening solution to the plate surface, and free of paper stains and stable printed matter with high image quality. Can be obtained.

The higher alcohol used in the emulsion ink composition for offset printing of the present invention is represented by the following general formula (1).

R ¹ —OH (1) wherein R ¹ is a saturated group having 8 to 24 carbon atoms,
Or represents a hydrocarbon group which may contain an unsaturated bond)

In the general formula (1), the hydrocarbon group represented by R ¹ and having 8 to 24 carbon atoms includes a linear or branched saturated aliphatic hydrocarbon group or unsaturated aliphatic hydrocarbon group. And a hydrogen group. If the carbon number of R ¹ is outside the above range, sufficient water separation cannot be obtained.

The higher alcohol represented by the above general formula (1) is, for example, a saturated alcohol having a carbon number in the range of 8 to 24, such as nonyl alcohol, lauryl alcohol, tridecanol, cetanol, stearyl alcohol, isostearyl alcohol and oleyl alcohol. Or an unsaturated monohydric alcohol can be exemplified.

The higher alcohol is contained in the emulsion ink composition for offset printing in an amount of 0.04 to 3.5.
% By weight. If the content of the higher alcohol is less than the above range, water separation does not sufficiently occur at a high shear rate of the printing press, and sufficient fountain solution cannot be supplied to the plate surface. As a result, water separation occurs at a low shear rate, and sufficient water does not reach the plate surface, and ink adheres to the non-image area to cause stain on the paper surface.

The nonionic surfactant used in the emulsion ink composition for offset printing of the present invention is represented by the following general formula (2).

R ² —O— [CH ₂ —CH ₂ —O] _n —H (2) wherein R ² is a saturated group having 4 to 24 carbon atoms,
Alternatively, a hydrocarbon group which may contain an unsaturated bond or an aromatic ring, n represents an integer in the range of 1 to 16, and when the number of carbon atoms of R ² is k, k and n are 1.5n ≦ k ≦ 6n Satisfy the relationship)

In the general formula (2), the hydrocarbon group represented by R ² and having 4 to 24 carbon atoms includes a linear or branched saturated aliphatic hydrocarbon group or unsaturated aliphatic hydrocarbon group. An aromatic hydrocarbon group, or an aromatic hydrocarbon group having a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. If the number of carbon atoms of R ^2, the number of n, and the relationship between k and n are out of the above ranges, the desired surface active effect cannot be obtained.

Examples of the nonionic surfactant represented by the general formula (2) include polyoxyethylene alkyl phenyl ethers such as ethylene oxide polyadduct of nonylphenol and ethylene oxide polyadduct of octyl phenol, and lauryl alcohol. And polyoxyethylene alkyl ethers such as ethylene oxide polyadducts.

The nonionic surfactant is contained in a total amount of the emulsion ink composition for offset printing in an amount of 0.0.
It is contained in an amount of 4 to 2.1% by weight. If the content of the nonionic surfactant is less than the above range, sufficient surface activity cannot be obtained,
On the other hand, if it exceeds the above range, water separation will not sufficiently occur because the emulsification is too stable.

The resin components used to obtain the emulsion ink composition for offset printing of the present invention include rosin-modified phenolic resins, petroleum resin-modified phenolic resins, various alkyd resins, petroleum resins, rosin ester resins, polyester resins, and Gilsonite. Alternatively, a modified product thereof can be used. These resin components may be gelled using a gelling agent.

As the colorant for obtaining the emulsion ink composition for offset printing of the present invention, colorless or colored inorganic or organic pigments generally used for offset printing inks can be used. Inorganic pigments such as titanium, barium sulfate, calcium carbonate, and magnetic iron oxide, azo pigments, lake pigments, phthalocyanine pigments, isoindoline pigments, organic pigments such as anthraquinone pigments, quinacridone pigments, and carbon black can be used.

Examples of the vegetable oil for obtaining the emulsion ink composition for offset printing of the present invention include soybean oil, cottonseed oil, linseed oil, safflower oil, tung oil, tall oil, dehydrated castor oil, canola oil and the like.

As the mineral oil for obtaining the emulsion ink composition for offset printing of the present invention, those which are used as ink solvents for offset printing can be used without particular limitation. Specifically, an n-paraffinic solvent,
Isoparaffinic solvents, naphthenic solvents, aromatic solvents, α-olefin solvents, spindle oils, machine oils,
Petroleum solvents such as cylinder oil can be exemplified. Specific examples of other solvents that can be used in combination include light oil, turpentine oil, mineral spirit, alcohols, ketones, esters, and the like.

Further, in order to obtain the emulsion ink composition for offset printing of the present invention, a pigment dispersant, a dryer, a drying retarder, an antioxidant, a surface-regulating aid, a set-off preventing agent, etc. are appropriately used. Can be.

The viscosity range of the oil component mainly composed of the coloring agent, the binder resin, and the vegetable oil and / or the mineral oil of the present invention is preferably 1 to 10 Pa · s.

The ratio of each of the above components in the oil component is 10 to 30% by weight of the coloring agent, 10 to 45% by weight of the binder resin, 0 to 60% by weight of the vegetable oil, and 0 to 0% by weight of the total amount of the oil component.
An appropriate range is 60% by weight (preferably the total amount of vegetable oil and mineral oil is in the range of 30 to 60% by weight).

As the aqueous component for obtaining the emulsion ink composition for offset printing of the present invention, water can be used. As the water, ion exchange water, distilled water, or the like can be used. The aqueous component may be mixed with a water-soluble organic solvent such as a polyhydric alcohol. Also, there is no problem even if a dampening solution used conventionally is used.

For producing the emulsion ink composition for offset printing of the present invention, a conventionally known method can be used. Hereinafter, a general production method used for obtaining the emulsion ink composition for offset printing of the present invention will be described.

Resin varnish, colorant, vegetable oil, mineral oil,
The base for offset printing ink is obtained by kneading and dispersing the pigment dispersant with a bead mill, a three-roll mill or the like as necessary.

In the base for the offset printing ink,
Higher alcohols and nonionic surfactants specified in the present invention, resin varnish that can be used if necessary, other additives are added if necessary, vegetable oil, solvent and the like to adjust the viscosity to a predetermined viscosity, offset printing ink Obtain the composition.

In the offset printing ink composition,
An aqueous component containing water as a main component is added and stirred to obtain an emulsion ink composition for offset printing.

Printing using the emulsion ink composition for offset printing of the present invention can be performed in the same manner as conventional offset printing except that a conventional dampening solution supply device is not used. As the plate material, those used in conventional offset printing can be used, and examples thereof include a PS plate.

[0037]

The emulsion ink composition for offset printing of the present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto unless it departs from the gist and scope of application. is not. In the following description, "parts" indicates parts by weight.

[Production of varnish for emulsion ink for offset printing] (Production of rosin-modified phenolic resin varnish) A rosin-modified phenolic resin (manufactured by Hitachi Chemical Polymer Co., Ltd.) was placed in a four-necked flask equipped with a condenser, a thermometer, and a stirrer. ,
Acid value 20, softening point 162 ° C) 40 parts, soybean oil 20 parts, 6
No. Solvent (manufactured by Nippon Petrochemical Co., Ltd.) was charged, heated to 230 ° C., stirred at the same temperature for 30 minutes, and allowed to cool, and 1 part of ethyl acetoacetate aluminum diisopropoxide as a gelling agent ( (ALCH manufactured by Kawaken Fine Chemicals Co., Ltd.) was charged and stirred at 175 ° C. for 30 minutes to obtain a rosin-modified phenol resin gel varnish.

(Production of Gilsonite Varnish) Gilsonite (manufactured by American Gilsonite Co., Ltd.) was placed in a four-necked flask equipped with a condenser, a thermometer, and a stirrer.
And 80 parts of No. 6 solvent, and the mixture was heated to 140 ° C. and stirred at the same temperature for 4 hours to obtain a Gilsonite varnish.

(Production of Petroleum Resin Varnish) Condenser,
A four-necked flask equipped with a thermometer and a stirrer was charged with 55 parts of petroleum resin (manufactured by Nippon Oil Co., Ltd.) and 45 parts of No. 6 solvent, heated to 140 ° C., and stirred at the same temperature for 30 minutes. A petroleum resin varnish was obtained.

[Production of Emulsion Ink Composition for Offset Printing] Examples 1 to 3, Comparative Examples 1 to 7 25 parts of rosin-modified phenolic resin varnish, 12 parts of Gilsonite varnish, 12 parts of petroleum resin varnish, carbon black # 32 20 parts (Mitsubishi Chemical Co., Ltd.) and 1 part of an anti-drying agent were blended and kneaded with a bead mill to obtain a black ink base.
Next, a higher alcohol, a nonionic surfactant, a petroleum resin varnish, and a No. 6 solvent were added to the black ink base at the compounding ratio shown in Table 1 and diluted to obtain a viscosity of 3.3 to 3.3.
An ink composition for offset printing of 3.5 Pa · s was obtained.

60 parts of each of the ink compositions for offset printing obtained above and 40 parts of water were stirred and mixed to obtain an emulsion ink composition for offset printing having a water content of 40% by weight.

[Performance Evaluation Test] (1) Printing Test Using each of the emulsion ink compositions for offset printing described above, offset printing was performed without using a conventional dampening solution supply device under the following printing machine and printing conditions, and the printing paper surface was printed. In particular, the non-image area was examined for dirt. The condition without stain was evaluated as 3, the condition with slight stain was evaluated as 2, and the condition with noticeable stain was evaluated as 1.
Table 2 shows the results. Printing machine: Offset rotary printing press Plate material: PS plate Paper: Newsprint Printing speed: Medium speed (5 m / sec) or high speed (10 m / sec)

(2) Water Separation State of Emulsion Ink on Ink Roller Offset printing is performed using each of the offset printing emulsions in the same manner as in the printing test, and the emulsion on the inking roller of the printing press is used. The ink was sampled and the state of separation of water was examined. Table 2 shows the results.

[0045]

[Table 1]

[0046]

[Table 2]

As is clear from the results in Table 2, the emulsion ink composition for offset printing of the present invention (Example 1)
When 4) is used, there is no stain on the printing paper surface. This is considered to be due to the proper separation of water from the emulsion ink composition for offset printing. on the other hand,
When the emulsion ink compositions for offset printing of Comparative Examples 1 to 7 were used, the printing paper surface was stained.
This is thought to be because a sufficient amount of water was not separated or, conversely, was separated too much.

[0048]

EFFECT OF THE INVENTION In offset printing, by using the emulsion ink composition for offset printing of the present invention containing a specific higher alcohol and a nonionic surfactant, effective water separation on a roller during printing. And good offset printing can be performed without using a dampening solution supply device as in the related art.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Takashi Iwase 1-23-23, Edobori, Nishi-ku, Osaka-shi F-term in Sakata Inks Co., Ltd. 2C034 AA08 2H113 AA03 AA04 BA06 BC02 4J039 AB04 AB05 AB08 AD18 AE02 AE06 AE07 BA04 BA13 BA16 BA18 BC07 BC12 BC17 BC29 BC39 BC50 BE01 BE09 BE22 CA06 GA02 GA03

Claims (2)

[Claims] 1. An oily component containing a colorant, a binder resin and a vegetable oil and / or a mineral oil as main components in an amount of 70 to 40% by weight, and an aqueous component mainly containing water in an amount of 30 to 60%.
% Of an emulsion ink composition for offset printing, comprising 0.04 to 3.5% by weight of a higher alcohol represented by the following general formula (1) in the entire ink composition; An emulsion ink composition for offset printing, comprising 0.04 to 2.1% by weight of the nonionic surfactant represented by the formula (1). R ¹ —OH (1) R ² —O— [CH ₂ —CH ₂ —O] _n —H (2) (wherein, R ¹ is a saturated group having 8 to 24 carbon atoms;
Alternatively, a hydrocarbon group which may contain an unsaturated bond is represented by R ²
Represents a saturated or unsaturated hydrocarbon group having 4 to 24 carbon atoms and optionally containing an unsaturated bond or an aromatic ring;
Represents an integer in the range 1-16, and when the number of carbon atoms in R ² and k, k and n satisfy the relation of 1.5n ≦ k ≦ 6n) 2. An offset printing method using the emulsion ink composition for offset printing according to claim 1 without using a dampening solution supply device.