JP2924473B2 - Pigment composition for offset ink and use thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigment composition for an offset ink which is excellent in fluidity of a dispersion having a high pigment concentration, particularly excellent in fluidity in a state of being heated during a dispersion step, and a high pigment concentration using the same. The present invention relates to a method for producing a dispersion.

[0002]

2. Description of the Related Art Generally, in order to exhibit a clear color tone and a high tinting strength in an offset ink composition, it is necessary to make the pigment dispersion finer in a vehicle. In this dispersion step, dispersion with a high pigment concentration is generally performed to improve production efficiency, and then various vehicles and solvents are mixed to prepare a printing ink.

Generally, the fluidity of a dispersion having a high pigment concentration is temperature-dependent, and the fluidity improves as the temperature increases. Therefore, dispersion at a high temperature is advantageous from the viewpoint of production efficiency. However, a dispersion having a high pigment concentration has a critical temperature, and when the temperature exceeds a certain temperature, the dispersion loses its fluidity, and even when heated, the fluidity does not increase, and on the contrary, a phenomenon occurs. This critical temperature is around 50-90 ° C., which is the same as the dispersion temperature during the dispersion step. For this reason, dispersion of a high pigment concentration at or above the critical temperature is not only caused by poor dispersion, but also taken out from the disperser,
Transport becomes difficult, and a dispersion having a high pigment concentration cannot be obtained, which hinders improvement in production efficiency. This phenomenon is remarkably exhibited in a dispersion having a high pigment concentration of the offset ink. In addition, if the pigment dispersion prepared as a product also has poor fluidity, it causes a decrease in gloss and poor printability.

In order to solve the above various problems, Japanese Patent Publication No. 58-28303, Japanese Patent Publication No. 59-40172,
JP-A-58-167654, JP-A-59-168070, JP-B-63-2
No. 0869, JP-B-58-28303, JP-B1-34268 and JP-B1-34269, improvements have been made by known compounds having an acidic or basic group introduced into the pigment skeleton. Has little effect because the organic solvent content is small. JP-A-63-363 describes a method of mixing a compound obtained by introducing a substituent of a polymer resin into a side chain, but the fluidity improving effect in a high pigment concentration dispersion is insufficient. And there is no effect of increasing the critical temperature.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there are provided a pigment composition for an offset ink and an offset ink composition which have improved the above-mentioned drawbacks and have increased the fluidity of a high-concentration pigment dispersion and the critical temperature of the fluidity. Is provided.

[0006]

SUMMARY OF THE INVENTION A pigment composition for offset ink comprising 100 parts by weight of an organic pigment and 1 to 15 parts by weight of an aliphatic dicarboxylic acid having 3 to 7 carbon atoms, and the offset ink in a vehicle for ifset ink. The present invention relates to a method for producing a high pigment concentration dispersion, wherein 10 to 40% by weight of a pigment composition is mixed and dispersed.

The organic pigment represented by the present invention includes, for example, at least one selected from azo (soluble azo pigment, insoluble azo pigment), phthalocyanine (blue pigment, green pigment), and dioxazine purple pigment. .

The aliphatic dicarboxylic acid of the present invention has 3 carbon atoms.
~ 7 aliphatic dicarboxylic acids can be used. Aliphatics may include saturated aliphatic systems, unsaturated aliphatic systems and isomers thereof. Specific compounds include malonic acid, succinic acid,
Glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid and the like.

The amount of dicarboxylic acid added is 100
The amount is preferably 1 to 15 parts by weight with respect to parts by weight. If the amount is less than 1 part by weight, the effect of improving the fluidity is small, and if the amount is more than 15 parts by weight, the effect of the amount used is not obtained, and the coloring power is undesirably reduced.

In the method of treating dicarboxylic acid, the desired effect can be sufficiently obtained by simply mixing the organic pigment powder and dicarboxylic acid. However, 2 equivalents or more of sodium hydroxide is used per 1 mol of dicarboxylic acid aqueous solution or dicarboxylic acid. , Potassium hydroxide and other alkali metal hydroxides and water at room temperature to 80 ° C
The solution prepared by adding the alkali metal salt of dicarboxylic acid to the organic pigment slurry is mixed and then weakened to make the alkali metal salt of dicarboxylic acid return to dicarboxylic acid, and the surface of the pigment is coated with dicarboxylic acid. Further better results can be obtained by drying the slurry with a fluidized-bed dryer, a spray dryer or the like, melting the dicarboxylic acid by heat, and forming a tight coating layer on the pigment.

The pigment composition of the present invention is used for offset ink. The offset ink comprises 3 to 40% by weight of the pigment composition of the present invention, and a vehicle 45 for the offset ink.
-97% by weight, other adjuvants and extender pigments 0-20% by weight, and the vehicle for offset ink is rosin-modified phenolic resin, petroleum resin, alkyd resin, or
20 to 50% by weight of these dry oil-modified resins and 0 to 30% by weight of vegetable oils such as linseed oil, tung oil and soybean oil, n-
It is composed of 10 to 60% by weight of a solvent such as paraffin, isoparaffin, aromatec, naphthene and α-olefin. In addition, known additives such as an ink solvent, a dryer, a leveling improver, and a thickener are appropriately blended to obtain an offset ink.

The pigment composition of the present invention is useful for producing a high pigment concentration dispersion of an offset ink. That is, the pigment composition is blended at a high concentration of 10 to 40% by weight, preferably 15 to 35% by weight with respect to the vehicle for offset ink, and the temperature is 40 to 120 ° C, preferably 60 to 120%.
Disperse at 100 ° C. Even if the dispersion temperature is lower than 40 ° C,
Alternatively, if the temperature is higher than 120 ° C., the fluidity of the high pigment concentration dispersion is undesirably reduced. As the disperser, a dissolver, a high-speed mixer, a homomixer, a sand mill, a roll mill, an attritor, a kneader and the like are used. As the dispersion method, the powdery pigment composition is used for dispersion, but the drying step can be omitted and the paste-like pigment composition can be directly dispersed by flashing using a flasher or the like.

The resulting high pigment dispersion is diluted with an offset ink vehicle and used as an offset ink. As the action mechanism of the pigment composition of the present invention, dicarboxylic acid surface-treated on pigment particles contributes to the formation of a resin adsorption layer, and the affinity between the dicarboxylic acid and the resin component contained in the vehicle for offset ink is increased. It is estimated that the flowability of the pigment concentration dispersion is improved.

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

Example 1 100 parts of β-type copper phthalocyanine blue (CI Pigment Blue 15: 3) and 5 parts of adipic acid were mixed and pulverized.
A pigment composition was obtained. 15 parts of the pigment composition and 35 parts of a rosin-modified phenol resin varnish were dispersed by a sand mill until the particle size became 10 μm or less to prepare a base ink for offset ink. The obtained base ink for offset ink is
The higher the temperature, the higher the fluidity was, showing excellent fluidity at 80 ° C.

Comparative Example 1 A base ink for offset ink prepared in the same manner as in Example 1 by using β-type copper phthalocyanine blue (CI Pigment Blue 15: 3) not subjected to adipic acid treatment in Example 1. Has a maximum value at 60 ° C and 80 ° C
Was inferior in fluidity.

Comparative Example 2 The base ink for offset ink prepared in the same manner as in Example 1 except that adipic acid was changed to stearic acid was inferior to Example 1 in fluidity at 80 ° C.

EXAMPLE 2 A paste-like pigment containing 100 parts of β-type copper phthalocyanine blue (CI pigment blue 15: 3) was mixed with 500 parts of water.
And a solution prepared by dissolving 5 parts of adipic acid together with 100 parts of water at 70 ° C. was added to the slurry obtained by stirring, and mixed at 70 ° C. for 30 minutes. PH with hydrochloric acid
Was adjusted to 6, and a pigment composition was obtained by spray drying. The base ink for offset ink prepared by the same operation as in Example 1 showed excellent fluidity at 80 ° C.

Example 3 A pigment composition was obtained in the same manner as in Example 1 except that adipic acid was changed to malonic acid. The base ink for offset ink adjusted by the same operation as in Example 1 was 80 ° C.
Showed excellent fluidity.

Example 4 A pigment composition was obtained in the same manner as in Example 1 except that adipic acid was changed to suberic acid. The base ink for offset ink adjusted by the same operation as in Example 1 was 80
Excellent fluidity at 0 ° C.

Example 5 Soluble azo (CI Pigment Red 57: 1) 100
And 5 parts of adipic acid were mixed and pulverized to obtain a pigment composition.
The base ink for offset ink prepared by the same operation as in Example 1 showed excellent fluidity at 80 ° C.

Comparative Example 3 The soluble azo (C.I.
I. Pigment Red 57: 1) and the fluidity at 80 ° C. of the base ink for offset ink prepared by the same operation as in Example 1 was poor.

Example 6 Insoluble azo (CI Pigment Yellow 12) 100
And 5 parts of adipic acid were mixed and pulverized to obtain a pigment composition.
The base ink for offset ink prepared by the same operation as in Example 1 showed excellent fluidity at 80 ° C.

Comparative Example 4 Insoluble azo (C.I.
I. Pigment Yellow 12), the fluidity at 80 ° C. of the base ink for offset ink adjusted by the same operation as in Example 1 was poor.

Example 7 100 parts of copper phthalocyanine green (CI Pigment Green 7) and 5 parts of adipic acid were mixed and pulverized to obtain a pigment composition. The base ink for offset ink prepared by the same operation as in Example 1 showed excellent fluidity at 80 ° C.

Comparative Example 5 A base ink for offset ink prepared at 80 ° C. in the same manner as in Example 1 except that copper phthalocyanine green (CI Pigment Green 7) which was not treated with adipic acid in Example 7 was used. The fluidity was poor.

Example 8 100 parts of dioxazine violet (CI Pigment Violet 23) and 5 parts of adipic acid were mixed and pulverized.
A pigment composition was obtained. The base ink for offset ink prepared by the same operation as in Example 1 showed excellent fluidity at 80 ° C.

Comparative Example 6 The base ink for offset ink prepared at 80 ° C. in the same manner as in Example 1 using dioxazine violet (CI Pigment Violet 23) which was not treated with adipic acid in Example 8. The fluidity was poor.

Table 1 shows the fluidity of the base ink for offset ink using the pigment composition according to the present invention. The flowability was evaluated by measuring the length of 1 cc of ink at 80 ° C. flowing for 10 minutes at 80 ° C. using a glass plate flowmeter of JIS K5702. The larger the value, the better the fluidity.

[0029]

[Table 1]

[0030]

According to the present invention, it is possible to provide an offset ink composition in which the fluidity of a high-concentration pigment dispersion and the critical temperature of the fluidity are increased.

[0031]

[Brief description of the drawings]

FIG. 1 is a graph showing the influence of the fluidity temperature of the base ink for offset ink using the pigment compositions of Example 1 and Comparative Example 1.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09D 11/00-11/20

Claims (2)

(57) [Claims] 1. A pigment composition for offset ink comprising 100 parts by weight of an organic pigment and 1 to 15 parts by weight of an aliphatic dicarboxylic acid having 3 to 7 carbon atoms. 2. A method for producing a high pigment concentration dispersion, comprising mixing and dispersing 10 to 40% by weight of the pigment composition for offset ink according to claim 1 in a vehicle for offset ink.