JPH061852A - Aqueous pigment dispersion - Google Patents

Abstract

(57) [Summary] [Purpose] To solve the problems of increasing the viscosity with time, decreasing the density and gloss, and changing the hue when a calcium lake monoazo pigment is applied to an aqueous printing ink. An aqueous pigment dispersion comprising a calcium lake monoazo pigment having an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid as a coupler component, an inorganic acid zinc salt, and an aqueous resin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous pigment dispersion, particularly to an aqueous pigment dispersion useful as an aqueous printing ink.

[0002]

2. Description of the Related Art Conventionally, a monoazo lake pigment obtained by coupling an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid such as β-oxynaphthoic acid as a coupler component has been used for printing ink, paint, plastic coloring, etc. Widely used in various applications. The water resistance of monoazo lake pigments is not always sufficient, and troubles in the printing process tend to occur. Therefore, studies have been made to improve the water resistance of the pigment itself by surface treatment of the pigment.

Among them, C.I. I. Pigment Red 5
When 7: 1 is used in a water-based printing ink, for example, a water-based gravure printing ink, a water-based flexographic printing ink, etc., problems such as increase in viscosity during ink preparation, thickening after ink preparation, and gelation may occur. . In addition, the printed matter obtained using this ink has a problem that the gloss and the density are lower than those obtained from the organic solvent-based printing ink, and the hue changes from bluish red to yellowish red. Have
Therefore, C.I. I. It was difficult to use Pigment Red 57: 1 as a pigment for water-based ink.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides an aqueous calcium lake monoazo pigment obtained by coupling an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid such as β-oxynaphthoic acid as a coupler component. It is intended to solve the problems that when applied to printing ink, increase in viscosity with time, decrease in density and gloss, and change in hue occur.

[0005]

The invention according to claim 1 of the present application is a calcium lake monoazo pigment having an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid as a coupler component, an inorganic acid zinc salt, and an aqueous solution. An aqueous pigment dispersion comprising a resin, wherein the invention according to claim 2 is an inorganic acid zinc salt in an aqueous slurry of a calcium lake monoazo lake pigment containing an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid as a coupler component. The present invention relates to a water-based pigment dispersion comprising a surface-treated pigment having a surface treatment added thereto and a water-based resin.

Examples of the aromatic amine having a soluble group in the present invention include 1-amino-4-methylbenzene-2-sulfonic acid (p-toluidine-m-sulfonic acid) and 1-amino-4-methyl- 5-chlorobenzene
2-sulfonic acid, 1-amino-4-chloro-5-methylbenzene-2-sulfonic acid, 1-amino-4-methylbenzene-3-sulfonic acid, 1-amino-3-methyl-4
-Sulfonic acid etc. A typical example of the coupler component of the monoazo pigment of the present invention is β-oxynaphthoic acid, which is substituted with a lower alkyl group such as a methyl group or an ethyl group, an alkoxy group or a halogen atom at a substitutable position of the naphthalene ring. It may be a substituted β-oxynaphthoic acid.

The calcium lake monoazo pigment of the present invention can be produced by a known method. That is, the coupling reaction is carried out by dropping a coupler solution prepared by dissolving β-oxynaphthoic acids in an alkaline solution into a solution obtained by diazotizing an aromatic amine having a soluble group by a conventional method. Lake formation may be carried out at the same time as the coupling by adding it to the diazo component as an aqueous solution of calcium salt such as calcium chloride or calcium nitrate, or in the solution of the monoazo dye obtained by the coupling reaction. You may perform it by adding an aqueous solution.

The calcium lake monoazo pigment of the present invention may be treated with rosin. The rosin treatment is preferable because it improves color transparency and density. The treatment of the pigment with rosin may be performed by adding an alkali-soluble salt of rosin to the monoazo dye, or may be added in advance as a soluble salt of rosin in the coupler component. The amount of rosin used is 30% by weight or less, preferably 1 to 10% by weight, based on the pigment.

The present invention is an aqueous pigment dispersion prepared by adding an inorganic acid zinc salt to the above-mentioned calcium lake monoazo pigment. Examples of the inorganic acid zinc salt include zinc nitrate, zinc chloride, zinc sulfate and zinc carbonate.

The inorganic acid zinc salt is obtained by adding 0.5 to 10% by weight, preferably 1 to 5% by weight to the calcium lake monoazo pigment. When the content of the inorganic acid zinc salt is less than 0.5% by weight, an increase in viscosity and a change in hue cannot be avoided when the aqueous dispersion is prepared, and conversely, when the content is 5% by weight, particularly 10% by weight or more, It is not preferable because the vividness of the color is lowered and the gloss is also lowered.

The inorganic acid zinc salt may be dry blended with the calcium lake monoazo pigment, or may be added to an aqueous monoazo dye solution or a water slurry of the pigment. In some cases, it may be added in advance in the diazo component. Preferably, it is added to the pigment slurry and the pH is adjusted to 8
As described above, the pH is preferably kept at 9 to 12 and kept for 5 to 90 minutes. It is considered that the surface of the pigment is treated with zinc hydroxide generated by hydrolysis of the zinc salt by this treatment. Further, when producing the aqueous pigment dispersion of the present invention, the monoazo lake pigment, the inorganic acid zinc salt and the aqueous resin may be blended separately.

The water-based resin of the present invention is a water-dispersible resin or water-soluble resin such as styrene-acrylic copolymer system, styrene-maleic acid copolymer system, acrylic copolymer system, alkyd system, epoxy system, polyester system, urethane system and the like. However, a styrene-acrylic copolymer water-dispersible resin is particularly preferable.

The styrene-acrylic copolymer resin is obtained by emulsion polymerization of 10 to 50% by weight of styrene, 5 to 40% by weight of (meth) acrylic acid and 10 to 35% by weight of (meth) acrylic acid alkyl ester. The molecular weight is 1,000 to 500,000 and the acid value is 10 to 500.
Resin. Examples of the alkyl ester of (meth) acrylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth).
N-butyl acrylate, isopropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
Examples include n-hexyl acrylate and lauryl (meth) acrylate. The water-dispersible resin can be produced by dropping a mixture of the monomers into an aqueous medium to which an emulsifier is added and emulsion-polymerizing the mixture. A high molecular weight dispersant may be used instead of or in combination with the emulsifier.

The method for producing the aqueous pigment dispersion of the present invention may be such that the pigment composition of the present invention is dispersed in an aqueous resin by a disperser such as a paint conditioner or a jar mill. Further, the inorganic acid zinc salt may be added to the pigment dispersion prepared by dispersing the calcium lake pigment of the aqueous resin in the same manner as described above. The pigment concentration in the aqueous pigment dispersion is 5-40% by weight. Of these, those with a pigment concentration of 30% by weight or more
It can be used as a concrete base for printing inks and paints. Hereinafter, the present invention will be described with reference to examples. In the example,
Parts represent parts by weight, and% represents% by weight.

Example 1 18.7 parts of p-toluidine-m-sulfonic acid was added to 300 parts of water.
Parts and 4 parts caustic soda. 35% hydrochloric acid 23
Parts, and after acid precipitation, 200 parts of ice is added and cooled to 0 ° C. Add 7 parts of sodium nitrite dissolved in 25 parts of water,
% Aqueous solution of calcium chloride (58 parts)
What was stirred for a minute was used as the diazo component. On the other hand, 18.7 parts of β-oxynaphthoic acid was added to 200 parts of water and 9.1 parts of caustic soda.
And then added with 42.4 parts of 10% rosin soap (10% based on the dye content) as a coupler component.

The coupler component is added dropwise to the diazo solution over a period of 3 minutes to carry out a coupling reaction and a lake reaction. The pH at the end of coupling and lake formation was 11.2. This pigment slurry was mixed with 5.9 parts of zinc nitrate and 5 parts of water.
When a solution dissolved in 0 part was added, the pH dropped to 7.1. The pH was adjusted to 11.0 with a 4.8% sodium hydroxide solution, stirred for 30 minutes, heated to 80 ° C., and further stirred for 30 minutes. After filtration, washing with water, and drying, 48.8 parts of a surface-treated azo lake pigment (A2) was obtained. Further, a monoazo lake pigment (A1) was prepared by filtering and drying the pigment slurry before adding zinc nitrate.

Example 2 Example 1 except that 10% rosin soap was not added.
In the same manner as the surface-treated azo lake pigment (B1) and the monoazo lake pigment (B1) not treated with zinc nitrate.
2) was obtained.

Example 3 A surface-treated pigment (A3) was obtained in the same manner as in Example 1 except that 4.1 parts of zinc chloride was added to the pigment slurry obtained in Example 1 instead of zinc nitrate.

Example 4 Zinc nitrate 0.5 was added to the dry pigment (A1) obtained in Example 1.
Parts were dry blended to obtain a pigment (A4).

Example 5 Zinc carbonate was added to the dry pigment (A1) obtained in Example 1 in an amount of 0.3.
3 parts were dry blended to obtain a pigment (A5).

The pigment obtained in each example was subjected to an aqueous gravure ink test by the following method. 11 parts of pigment, styrene acrylic acid-based water-based varnish (LOX GT EXTENDE
R, Toyo Ink Mfg. Co., Ltd.) 34.5 parts and glass beads (diameter 3 mm) 150 parts were placed in a glass bottle container and dispersed for 90 minutes with a paint conditioner,
An aqueous ink was prepared by adding 54.5 parts of an aqueous varnish.
The results of viscosity and hue of the water-based ink after this adjustment are shown in Table 1.
It was shown to. Table 1 also shows the results of viscosity and hue after accelerating the adjusted ink at 40 ° C. for 1 week, and the result of color difference from the adjusted ink to the aged ink.

The hue (H value) and color difference (ΔE value) were measured by a spectrocolorimeter. Regarding the hue (H value), a larger value indicates a yellowish red color, and a smaller value indicates a bluish red color. The smaller the color difference (ΔE value), the smaller the change.

[0023]

[Table 1]

[0024]

INDUSTRIAL APPLICABILITY The aqueous pigment dispersion of the present invention does not cause thickening and gelation, and is significantly improved in terms of concentration decrease and hue change as compared with the case where the conventional pigment is used as it is. In addition, since it can be used as a water-based printing ink instead of the gravure printing ink that has been conventionally used as an organic solvent-based printing ink, it is possible to reduce the volatilization of organic solvents into the atmosphere, which is also excellent in terms of safety and hygiene. Printing ink can be provided.

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Claims (2)

[Claims] 1. An aqueous pigment dispersion comprising a calcium lake monoazo pigment having an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid as a coupler component, an inorganic acid zinc salt, and an aqueous resin. 2. A surface-treated pigment obtained by adding a zinc salt of an inorganic acid to a water slurry of a calcium lake monoazo lake pigment containing an aromatic amine having a soluble group as a diazo component and an oxynaphthoic acid as a coupler component, and a surface treatment pigment. An aqueous pigment dispersion comprising an aqueous resin.