JPH0629372B2 - 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 is directed to a pigment dispersion having a low viscosity even when the dispersion has a high pigment concentration, and excellent in gloss and sharpness. The present invention also relates to a method for producing the pigment dispersion, and further provides 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. For pigment dispersions that use rosin-based resin, shellac, polyamide, vinyl resin, urethane resin, nitrocellulose, cyclized rubber or chlorinated rubber as vehicle resin, the printability, dryability, gloss and clarity of printing ink It has excellent properties and is used for various purposes.

Further, for example, in a 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, in a pigment dispersion using a vehicle resin, a soluble azo pigment having an oxynaphthoic acid such as β-oxynaphthoic acid as a coupler, and an organic solvent, a pigment content of 10
When the pigment dispersion is manufactured in a weight percentage, the viscosity and the coloring strength, which are not problems, are deteriorated in the concrete pigment dispersion in which the concentration is about 25 wt%. That is, the viscosity of the conc. Pigment dispersion becomes high, and for example, the amount of the solvent diluted to a viscosity suitable for printing increases, resulting in a decrease in gloss and coloring power, which is a fatal defect in the obtained printing ink, paint, etc. Will have.

To reduce the viscosity, it is necessary to neatly disperse the pigment particles, 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 comprises a vehicle resin, a soluble azo pigment having an oxynaphthoic acid coupler as a coupler, and an aromatic hydrocarbon solvent as main components, and 1 to 20 parts by weight based on 100 parts by weight of the pigment. Part of the oxynaphthoic acid is used as a pigment dispersion pair, and the pigment particles are dispersed in an amount of 1 to 20 parts by weight based on 100 parts by weight of the oxynaphthoic acid to improve the dispersion of the pigment particles. The present invention provides a method for producing a pigment dispersion that has a high viscosity. That is,
The present invention focuses on oxynaphthoic acids which are a raw material for a soluble azo pigment having oxynaphthoic acids as a coupler, and the oxynaphthoic acids that are familiar with the pigment are used to improve the dispersion of pigment particles to reduce the viscosity. Is.

Soluble azo pigments containing oxynaphthoic acids as couplers are 0.3 times more than those which are usually synthesized, filtered, and washed with water.
~ 0.7 wt% unreacted oxynaphthoic acids are included. However, as described above, even if the meat is kneaded in a state containing the unreacted oxynaphthoic acids, it cannot be expected to reduce the viscosity.

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, ethylcellulose, polyamide, ring. It is a resin of one kind or two or more kinds selected from epoxidized rubber and chlorinated rubber. Preferred are vehicle resins such as rosin resins and nitrocellulose, which are highly effective in pigment dispersions having a high pigment concentration.

The pigment of the present invention is a soluble azo pigment having β-oxynaphthoic acid, β-oxynaphthoic acid substituted with a lower alkyl group, an alkoxy group or a halogen atom as a coupler, and is typically Brilliant Carmine 6B type. It is a pigment. It is a soluble azo pigment obtained by coupling a diazo component containing p-toluidine-m-sulfonic acid as a main component with a coupler component containing β-oxynaphthoic acid as a main component, and forming a lake with calcium chloride or the like. One example of a commercially available soluble azo pigment is Lionol.
Red 7B 4403, Lionol Red 6B
4295G (all manufactured by Toyo Ink Mfg. Co., Ltd.) and the like. The metal salts used for lake formation include calcium,
Barium, strontium, magnesium zinc, manganese, etc. 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 soluble azo pigments having oxynaphthoic acids as couplers may be used in combination.

The organic solvent of the present invention is one or more solvents selected from aromatic hydrocarbons, esters, ketones and the like, and examples thereof include solvents such as toluene, xylene, ethyl acetate, acetone, normal hexane and isopropyl alcohol. Is.

In the present invention, β-oxynaphthoic acid, β substituted with a lower alkyl group, an alkoxy group or a halogen atom is used.
Oxynaphthoic acids such as oxynaphthoic acid and α-oxynaphthoic acid are added or introduced in an amount of 1 to 20 parts by weight per 100 parts by weight of the pigment before, at the same time as or after kneading. Pigment 1 including unreacted oxynaphthoic acids contained in the pigment
It is 1 to 20 parts by weight with respect to 00 parts by weight. If it is less than 1 part by weight, the effect of reducing the viscosity is not seen, and if it exceeds 20 parts by weight, the coloring power is decreased. The method of adding oxynaphthoic acids is not particularly limited, and it is preferable to add it to the pigment dispersion at the time of kneading because it is excellent in the effect of reducing the viscosity. It is carried out by addition to the pigment, resin and solvent to the composition, addition to the solvent, addition of the pigment, resin and solvent to the composition, addition to the composition after kneading.

The method for producing the pigment dispersion includes vehicle resin, pigment,
A composition containing oxynaphthoic acids and a solvent is premixed, if necessary, 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 ink-based inks such as gravure inks with a high pigment concentration, the viscosity can be reduced and the gloss and 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.

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.

Example 1 Lionol Red 7B 4403 (Brilliant Carmine 6B pigment manufactured by Toyo Ink Mfg. Co., Ltd.) 24.625% β-oxynaphthoic acid 0.375% Lime rosin varnish (55% rosin, 45% toluene) 31% Toluene 23 % 225 parts of the composition and 300 parts of steel balls were placed in a ball mill and kneaded for 16 hours. After kneading, 15 parts of lime rosin varnish and 6 parts of toluene were added, well dispersed, and the ink was taken out. This is called base ink.

To 20 parts of this base ink, 26 parts of lime rosin and toluene for adjusting the printing viscosity were added to produce a gravure ink for publication.

For comparison, a base ink was produced in the same manner without adding only β-oxynaphthoic acid in the above composition, and further a gravure ink for publication was produced.

6/60 with B type viscometer for the obtained base ink
When the rpm value was measured, it was 150 cps / 150 cps for the ink added with β-oxynaphthoic acid, whereas it was 1080 cps / 552 for the ink without addition.
It was cps. In addition, the printed matter printed with each gravure ink for publication, to which β-oxynaphthoic acid was added, had improved gloss and sharpness. That is, the gloss was measured with a gloss meter on the coated paper, and the 60-degree reflectance was 28.5% when β-oxynaphthoic acid was not added, while β-oxynaphthoic acid was added. In the example, it was improved to 59.4%. The sharpness was visually evaluated.

Examples 2 to 4 In the composition of Example 1, the pigment was added to Lionol Red.
6B 4295G (Brilliant Carmine 6B pigment manufactured by Toyo Ink Mfg. Co., Ltd.)
Instead of xylene / normal hexane (90/5/5), the addition amount of β-oxynaphthoic acid was 100
Base inks and inks were produced in the same manner as in Example 1 for 5 types of 0 parts, 0.6 parts, 1 part, 2 parts and 4 parts.

When the 6/60 rpm value of the base ink was measured with a B type viscometer, Example 5 In Example 1, β-oxynaphthoic acid was not added before kneading, a base ink was prepared, and then β-oxynaphthoic acid was added to this base ink and stirred.

The value of 6/60 rpm with a B-type viscometer was measured and found to be 139 cps / 97 cps.

Example 6 Lionol Red 7B 4403 9.8% β-oxynaphthoic acid 0.2% Nitrocellulose varnish (55% solids in toluene / ethyl acetate / isopropyl alcohol solution) 70% Plasticizer (DBP) 3% Solvent (acetic acid Ethyl / acetone) 20% was kneaded in the same manner as in Example 1 to produce a base ink.

6/60 with B type viscometer for the obtained base ink
When the rpm value was measured, it was 600/540.
On the other hand, in the above composition, in the comparative example in which β-oxynaphthoic acid was not added, it was 5800/3850. The present invention has improved gloss and sharpness.

Examples 7 and 8 In Example 6, instead of the nitrocellulose varnish, polyamide-nitrocellulose (Example 7) and cyclized rubber (Example 8) were used.

That is, Lionol Red 7B 4403
9.8%, 0.2% β-oxynaphthoic acid, 80% varnish containing polyamide and nitrocellulose with a solid content of 37.7%, and 10% organic solvent (tolulene / ethyl acetate / isopropyl alcohol / methanol). Base ink (Example 7), or Lionol Red 7
B 4403 9.8%, β-oxynaphthoic acid 0.2
%, Cyclized rubber varnish (50% solid content in toluene) 6
When the base ink consisting of 0% and 30% toluene (Example 8) was compared with that without β-oxynaphthoic acid, both Examples 7 and 8 showed a viscosity reduction effect of about 1/2. And improved gloss and sharpness.

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Claims (4)

[Claims] 1. A vehicle resin, a soluble azo pigment having oxynaphthoic acids as a coupler, and an organic solvent as main components, and 1 to 20 parts by weight of oxynaphthoic acids per 100 parts by weight of the pigment. Pigment dispersion. 2. The pigment dispersion according to claim 1, wherein the vehicle resin is one or more selected from rosin resins, nitrocellulose, polyamide and rubber. 3. A vehicle resin, a soluble azo pigment having oxynaphthoic acids as a coupler, and an organic solvent as main components, and kneaded in a state of containing 1 to 20 parts by weight of oxynaphthoic acids per 100 parts by weight of the pigment. A method for producing a pigment dispersion, comprising: 4. The method for producing a pigment dispersion according to claim 3, wherein the soluble azo pigment is a Brilliant Carmine 6B type pigment.