JPH0629373B2 - Pigment dispersion and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention provides a barium azo lake pigment having water of crystallization by adding water to obtain a dispersion having a high pigment concentration. The present invention provides a pigment dispersion having a low year and excellent in gloss and sharpness, a method for producing the pigment dispersion, and further, a pigment dispersion particularly useful for gravure printing ink.

(Prior Art) Printing inks such as gravure inks, paints, etc. are composed of vehicle resins, pigments, solvents, additives, etc. Pigment dispersions using rosin-based resin, shellac, polyamide, vinyl resin, urethane resin, nitrocellulose, cyclized rubber, chlorinated rubber or the like as a vehicle resin are used in various applications such as printing ink and paint.

As a pigment, soluble azo pigments (azo lake pigments) have a beautiful color tone, large coloring power, and are inexpensive.
It is widely used in applications such as gravure ink, but the viscosity of the ink is often high. When adjusting this to the printing viscosity, it is necessary to add a large amount of solvent,
There was a problem such as deterioration of gloss.

Further, for example, in the case of gravure printing ink, an ink is produced with a pigment content of about 10% by weight and diluted with a solvent to a viscosity suitable for printing to produce the ink.

However, due to cost reductions in manufacturing and transportation, there is an increasing tendency to produce a pigment pigment dispersion of CONK having a pigment content increased to about 25% by weight and dilute it to produce an ink.

However, a vehicle resin, a diazonium salt of a benzene-based amine or a naphthalene-based amine having at least one sulfonic acid group or a carboxyl group is used as a cyazo component, naphthols or oxynaphthoic acids are used as a coupler component, and coupling is performed with a barium salt. In the azo lake pigment having lake water of crystallization and a pigment dispersion mainly composed of an organic solvent, the viscosity is high, and for example, the amount of the solvent diluted to a viscosity suitable for printability increases, so that the gloss and the coloring power are reduced. Invited and obtained printing ink,
It has a fatal defect as a paint.

In order to reduce the viscosity, it is necessary to disperse the pigment particles in a stable state, and if the pigment particles become entangled and agglomerated, the viscosity will increase. Conventionally, in order to eliminate this drawback, measures such as using a special additive or preliminarily surface-treating the pigment have been adopted. Certainly, there are effective means for lowering the viscosity, but the price of the additive and the labor for manufacturing the pigment dispersion remain problems. That is, although additive treatment and surface modification of the pigment are performed to increase the manufacturing process of the pigment dispersion, these methods tend to increase the manufacturing cost.

(Problems to be Solved by the Invention) There has been a demand for a method that achieves a low viscosity of a pigment dispersion and does not require an increase in the number of manufacturing steps or the use of special additives.

[Structure of Invention]

(Means for Solving Problems) The present invention uses a vehicle resin, a diazonium salt of a benzene amine or a naphthalene amine having at least one sulfonic acid group or carboxyl group as a diazo component, and uses naphthols or oxynaphthoic acids. As a coupler component, an azo lake pigment having water of crystallization which is coupled and laked with a barium salt, and an organic solvent as a main component, and a pigment containing 0.5 to 10 parts by weight of water per 100 parts by weight of the pigment. It is a dispersion. The pigment is at least one selected from Pigment Red 48 and Pigment Red 49, and is a pigment dispersion containing 1 to 5 parts by weight of water with respect to 100 parts by weight of the pigment having water of crystallization, and the vehicle resin is rosin. One or two or more selected from resin-based resins and nitrocellulose. Furthermore, it is a method for producing a pigment dispersion, which comprises a vehicle resin, the above-mentioned azo lake pigment and an organic solvent as main components, and kneads in a state of containing 0.5 to 10 parts by weight of water per 100 parts by weight of the pigment.

The amount of water to be added to the barium azo lake pigment of the present invention which normally has saturated crystallization water or the barium azo lake pigment which has crystallization water but is not saturated is calculated as having saturated crystallization water. 0.5 to 10 parts by weight is added to 100 parts by weight of the azo lake pigment.

Vehicle resins used in the pigment dispersion of the present invention include gum rosin, wood rosin, tall oil rosin, rosin ester, lime-cured rosin, zinc-cured rosin, maleated rosin, fumarized rosin, nitrocellulose, ethyl cellulose, polyamide, It is a resin of one kind or two or more kinds selected from cyclized rubber, chlorinated rubber and the like. Vehicle resins such as lime-cured rosin, zinc-cured rosin and nitrocellulose, which are highly effective in pigment dispersions having a high pigment concentration, are preferred.

The pigment of the present invention is a pigment represented by Pigment Red 48 (Permanent Red), Pigment Red 49 (Resole Red) or the like. That is, a diazonium of a benzene-based amine or a naphthalene-based amine that has at least one sulfonic acid group or carboxyl group and may further have one or more substituents such as a lower alkyl group and a halogen atom. The salt is used as a diazo component, and β-naphthol, β-oxynaphthoic acid, or naphthol or oxynaphthoic acid, which is a substitution product of these lower alkyl groups, halogen atoms, etc., is used as a coupler component for coupling, and barium salt is used as a lake. It is an azo lake pigment having water of crystallization formed, and usually has 1 to 4 equivalents of water of crystallization with respect to barium metal.
Further, the coupling or the post-treatment is carried out by a usual method. In the present invention, organic and / or inorganic pigments other than the soluble azo pigment can be used together.

As the organic solvent of the present invention, one or two selected from aromatic hydrocarbons, aliphatic hydrocarbons, esters, ketones, etc.
More than one kind of solvent, for example, a solvent such as toluene, xylene, hexane, heptane, naphtha, ethyl acetate, acetone, isopropyl alcohol and the like.

In the present invention, water is added or introduced in an amount of 0.5 to 10 parts by weight with respect to 100 parts by weight of the pigment before, at the same time as or after the kneading. If it is less than 0.5 parts by weight, the effect of reducing the viscosity is small, and if it exceeds 10 parts by weight, the viscosity tends to increase and the coloring power decreases, which adversely affects. There is no particular limitation on the method of adding water, and it is preferable to add it to the pigment dispersion during kneading because it is excellent in the effect of reducing viscosity. Addition to pigments, addition of resins and solvents to compositions,
It is carried out by adding it to a solvent, adding a pigment, a resin and a solvent to a composition, adding it to a composition after kneading.

The method for producing the pigment dispersion includes vehicle resin, pigment,
If necessary, a composition containing water and an organic solvent is premixed and kneaded with a kneading machine such as a ball mill, a sand mill or a pebble mill.

The pigment dispersion according to the present invention can be directly produced as a printing ink, a paint or the like, or can be produced as what is called a conc base. The pigment concentration in the pigment dispersion is usually about 5 to 70% by weight. Particularly, it is effective for a dispersion having a high pigment concentration, which is referred to as a conc having a pigment concentration of 20% by weight or more.

As the pigment dispersion according to the present invention, in addition to the above main components,
Additives used in printing inks, paints, etc. can be added before, after, or simultaneously with kneading, if necessary.

The printed matter of the printing ink obtained according to the present invention has various problems such as a decrease in coloring power, a change in color tone, a decrease in gloss, opacity, poor fluidity, and particularly thickening and gelation which occur during long-term storage. The drawbacks are remarkably improved, and especially in the production of a CONK base ink having a high degree of concentration of Gravure ink, the viscosity can be reduced and the gloss and the sharpness can be improved. In addition, it is no longer necessary to use special costly manufacturing methods such as surface treatment and modification of pigments to reduce viscosity.

The reason why such an effect occurs is not necessarily clear, but when the above barium azo lake pigment forms a stable acocomplex and is dispersed in a varnish system, not only on the pigment side but also on the varnish system, It is expected that an aco-complex is formed, and it is considered that the dispersion is stable as a whole.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples. In the examples, "part" or "%" is based on weight.

The physical properties in the examples were measured by the following methods.

(1) Viscosity: The value at 6/60 (rpm) was determined with a BM type rotational viscometer.

(2) Gloss: Determined by the regular reflectance of the developed surface 60 ° / 60 °.

(3) Density: Measured by a densitometer with Gretaque.

Example 1 Tobiasic acid and β-naphthol were coupled, to which an alkaline aqueous solution of rosin and barium chloride were added,
Heat, filter, wash, and dry Pigment Red 4
9: 1 (saturated water of crystallization theoretical value 6.7%, actual value of Karl Fischer method 6.5%) was obtained. For this pigment, water 3
%, Crushed pigment 25 parts, lime rosin varnish (solid content 55%, solvent is toluene) 45 parts, toluene 3
0 part was charged into a ball mill and kneaded for 24 hours to produce a gravure ink (dispersion ink). After measuring the viscosity of this ink, 20 parts of lime rosin was added to 20 parts of this ink, further diluted with toluene, and the printing viscosity was adjusted to 15 seconds with a Zahn cup viscometer No. 3.

The adjusted ink thus obtained was spread on ace paper with a No. 4 bar coater to measure gloss and density. In addition,
The dispersion ink whose viscosity was measured was subjected to a aging test at 40 ° C. for 1 week, and the change in viscosity was also examined.

Comparative Example 1 Pigment Red obtained by the same method as in Example 1
A gravure ink was prepared and tested in the same manner as in Example 1 except that water was not added using 49: 1 (theoretical value of saturated water of crystallization 6.7%, actual value of Karl Fischer method 6.5%).

The results of Example 1 and Comparative Example 1 are shown in Table 1.

Example 2 45 parts of lime rosin varnish, 30 parts of toluene, 0.7 water
After 5 parts (corresponding to 3 parts to 100 parts of pigment to be charged later) were charged in a ball mill, Pigment Red 49: 1 obtained in Example 1 (saturated water of crystallization 6.5%).
A gravure ink was produced and tested in the same manner as in Example 1 except that 25 parts of a pigment pulverized without adding water was placed in a ball mill and kneaded for 24 hours.

Example 3 To 100 parts of the high-viscosity dispersion ink obtained in Comparative Example 1, 0.75 part (corresponding to 3 parts to 100 parts of pigment) was added, and after sufficiently stirring with a homomixer, the same procedure was performed. I did a test.

The test results of Example 2 and Example 3 are shown in Table 2.

Example 4 Sodium 4-methyl-5-chloroaniline-2-sulfonate and β-oxynaphthoic acid were coupled and heated, and then barium chloride was added, filtered, washed with water and dried to prepare Pigment Red 48: 1. (Saturated crystal water theoretical value 3.1
4%, actual value by Karl Fischer method 3.3%). 3% of water was added to this pigment, and the same test as in Example 1 was conducted on the crushed pigment.

Comparative Example 2 Pigment Red obtained by the same method as in Example 4
Using 48: 1 (theoretical value of saturated water of crystallization 3.14%, actual value of Karl Fischer method 3.3%), the same test as in Example 4 was performed except that water was not added.

The results of Example 4 and Comparative Example 2 are shown in Table 3.

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Claims (8)

[Claims] 1. A vehicle resin, a diazonium salt of a benzene-based amine or a naphthalene-based amine having at least one sulfonic acid group or a carboxyl group as a diazo component, and naphthols or oxynaphthoic acids as a coupler component for coupling. A pigment dispersion comprising an azo lake pigment having water of crystallization obtained by lake formation with a barium salt and an organic solvent as main components, and containing 0.5 to 10 parts by weight of water per 100 parts by weight of the pigment. 2. The pigment dispersion according to claim 1, wherein the pigment is at least one selected from Pigment Red 48 and Pigment Red 49. 3. The pigment dispersion according to claim 1, which contains 1 to 5 parts by weight of water based on 100 parts by weight of the pigment. 4. The pigment dispersion according to any one of claims 1 to 3, wherein the vehicle resin is one kind or two or more kinds selected from a rosin resin and nitrocellulose. 5. A vehicle resin, a diazonium salt of a benzene-based amine or a naphthalene-based amine having at least one sulfonic acid group or a carboxyl group as a diazo component, and naphthols or oxynaphthoic acids as a coupler component for coupling. An azo lake pigment having water of crystallization obtained by lake formation with a barium salt, and an organic solvent as main components, and kneaded in a state of containing 0.5 to 10 parts by weight of water with respect to 100 parts by weight of the pigment. Method for producing pigment dispersion. 6. The method for producing a pigment dispersion according to claim 5, wherein the pigment is at least one selected from Pigment Red 48 and Pigment Red 49. 7. The method for producing a pigment dispersion according to claim 5, which contains 1 to 5 parts by weight of water with respect to 100 parts by weight of the pigment. 8. The method for producing a pigment dispersion according to claim 5, wherein the vehicle resin is one or more selected from rosin resins and nitrocellulose.