JPS62161861A - Molded pigment for printing ink - Google Patents

Abstract

PURPOSE:The titled pigment requiring no grinding process, producing an extremely small amount of dust, having improved operation efficiency and extremely improved luster and coloring power, obtained by adjusting wet cake of organic pigment to a fixed range of water content. CONSTITUTION:Wet cake of organic pigment (preferably having granular shape of 1-50mmphi particle diameter or a bar shape of 1-30mmphi thickness and 1-30mmphi length) is molded into a shape for easy drying and dried until a water content reaches 20-55wt% (preferably 30-45wt%) to give the aimed pigment for aqueous flexography and offset printing.

Description

[Detailed description of the invention] The present invention relates to molded pigments for printing inks.

When organic pigments are used, they are required to have excellent hue, coloring power, hiding power, dispersion power, fluidity, kneading ability, solvent resistance, light resistance, weather resistance, water resistance, etc. Ru. These properties are closely related not only to the chemical structural formula but also to its crystal form or particle size, and in order to obtain the desired pigment, the crude pigment is subjected to various pigmentation treatments during or after synthesis.

The present invention relates to an improvement in the finishing process after a specific treatment in pigmentation treatment.

More specifically, the present invention is a molded pigment for printing ink, characterized in that the moisture content of the wet cake of the organic pigment is 20-55 mmφ.

The shaped pigment used in the present invention is obtained by forming a wet cake of organic pigment into a shape that easily dries out, and then forming the molded pigment into a shape that is easy to dry out.
Manufactured by drying until dry.

Conventionally, organic pigments that have been pigmented by various methods are either left as wet cakes or completely dried (generally with a water content of 5).
(wt% or less) and then used as a powder for various purposes.

However, in the case of dry powder, the following problems arise.

(1) Drying causes agglomeration of particles, which impairs dispersibility. Therefore, for practical use, pulverization is required, or a dispersion step is required at the stage of use.

(2) Dust is easily generated during the crushing process and subsequent handling, making the working environment worse.

(3) In the drying process, a considerable amount of time and energy is required to reduce the moisture content to 5% by weight or less.

On the other hand, in the case of a wet cake, the dispersibility is excellent because there is no step such as drying, but there are the following problems.

1) Due to the high moisture content, there are many restrictions on its use. For example, when used in water-based flexographic printing inks, if the water content is 55% by weight or more, there are considerable restrictions on use, and the required coloring density is often not achieved.

2) Many applications require separation of water, making this process irrational. For example, when a wet cake of pigment for printing ink is converted into ink, water must be separated from the varnish and the wet cake using a kneader or the like, and this process requires considerable time and effort.

3) Handling and transportation of wet cake is often irrational from an industrial perspective.

As a result of intensive studies to solve the above-mentioned drawbacks, the present inventors found that the molded pigment provided by the present invention eliminates the drawbacks of powder and wet cake, combines the advantages of both, and surprisingly provides It has been found that when the molded pigment is used, the gloss and tinting power are significantly improved compared to conventional products.

According to the present invention, there are the following advantages.

1) Since the treatment ends before the particles agglomerate due to drying, the dispersibility is extremely good compared to powder, and is almost the same as wet cake. Therefore, a crushing step is not necessary.

2) When handled, it can be handled in almost the same way as powder, and generates extremely little dust.

3) Drying takes an extremely short time and is energy saving.
This is advantageous in terms of work efficiency.

4) In the drying process, the quality of some pigments may deteriorate, resulting in a decrease in coloring power and opacity, but this does not occur in the present invention, and on the contrary, there is a tendency for gloss and coloring power to improve.

The organic pigments referred to in the present invention include azo-based, disazo-based,
Examples include anthraquinone pigments, phthalocyanine pigments, and condensation pigments. Particularly effective are azo pigments generally called lake pigments.

In the production of the molded pigment of the present invention, extrusion molding, pump extrusion molding, groove drum molding, and granular molding are used to mold the wet cake (usually moisture content 60-95% by weight) into a shape that is easy to dry uniformly. Examples include machines. Specifically, for example, the magazine "Chemical Factory Ji Vol. 22 No. 2 No. 28
- The one described on page 32 is exemplified.

For example, in the case of extrusion molding, the shape of the molding is granular with a particle size (diameter) of 1 to 50 mmφ, preferably 2 to 20 mmφ. If the particle size is too large, the drying efficiency tends to be lowered, and the surface becomes a powder pigment while the inside becomes wet, which is not preferable. On the other hand, if it is too small, air circulation becomes poor due to the dry condition, which is not preferable.

When molding into a columnar, rod-like, or udon-like shape, the diameter is 1-30mmφ and the length is 1-30m.
mφ, preferably a thickness and length of 2 to 15 mmφ.

As for the drying method, a horizontal airflow type, a ventilation type, etc. are used, and a ventilation type device in the form of a band is common.

In particular, in the present invention, it is advantageous in terms of efficiency to continuously perform molding and drying with a single-stage band-type drying and smoking machine equipped with an extruder, and controlling the speed of the mesh conveyor to bring the moisture content to the regulated value. .

The moisture content of the molded pigment, which is the object of the present invention, is an important factor and essentially varies depending on the type of pigment.
Typically 20-55% by weight, more preferably 30-50m
It is mφ.

Further, depending on the type of pigment, it is preferable that the azo type is 35-50% by weight, and the phthalocyanine type and condensed type is 30-45% by weight.

When the water content of the molded pigment exceeds 55% by weight, the pigment properties become close to those of a wet cake, while when it is less than 20% by weight, partial aggregation tends to occur, resulting in properties similar to those of powder. Undesirable.

The molded pigment of the present invention can be handled in exactly the same way as powdered pigments, such as color adjustment by mixing and blending, and bagging.

In particular, when the molded pigment of the present invention is used in the production of water-based flexo ink, it is possible to industrially advantageously obtain an ink that is easy to remove in minutes and has excellent gloss and coloring power. I can do it.

Furthermore, when used in the production of offset printing ink, the dehydration operation is minimal, there is no need for strong roll kneading, and there is no need to separate a large amount of water as with wet pigments. Therefore, drainage treatment of separated water (generally referred to as flushing water) is not necessary.

In the case of producing the molded pigment of the present invention, surfactants, various resins, etc. may be appropriately added during the process for the purpose of facilitating molding or improving pigment properties.

Next, the present invention will be explained in more detail with reference to Examples. In the examples, parts and % represent parts by weight and % by weight.

Example 1 Sodium P-toluidine-m-sulfonate as a diazo component,
Coupling is performed in an aqueous solvent using β-oxynaphthoic acid as a coupling component, and then rosin and calcium chloride are added, followed by filtration and washing with water to obtain a wet cake of monoazo lake pigment. (Moisture content: 77%) This was transferred to an extruder and molded to obtain a molded wet cake with a particle size of 5 mmφ.

This formed wet cake is placed in a band-type air permeable smoke dryer (manufactured by Ogawara Seisakusho), dried with hot air, and taken out. Moisture content approximately 40
% molded pigment was obtained.

When an offset printing ink was prepared using this molded pigment, an ink with excellent coloring strength, transparency, and gloss was obtained.

Example 2 Coupling is performed in an aqueous solvent using 1-acetoacetylamino-2-methylbenzene as a coupling component and 3.3-')ri-oBtbenzidine as a diazo component, followed by filtration and washing with water to wet the disazo pigment. Cake (moisture content 73%
).

Transfer this to an extrusion molding machine and mold it to obtain a particle size of 10111f.
A shaped wet cake of fiφ is obtained.

This shaped wet cake is continuously fed to a single-stage band type dry smoke machine, and forced to pass through hot air at 80-100°C to dry-explode it. At this time, the passage time is adjusted so that the water content is 40-50%. A molded pigment with a water content of 45% was obtained.

For comparison, flexo printing ink was prepared using this molded pigment, powder pigment, 50 parts of wet cake as pigment, and 200 parts of styrene-maleic acid water-soluble resin varnish using a ball mill, and the colors were spread on paper for comparison. The results are shown in the table.
Example 3 4-Methyl-5-chlor using the same wet cake (water content 2%) *※) Using the wet cake (water content 73%) as is. Coupling was carried out in an aqueous solvent using sodium aniline-2-sulfonate as a diazo component and β-oxynaphthoic acid as a coupling component, and then strontium chloride was added, followed by filtration and washing with water to form a wet cake of monoazo lake pigment (water-containing 70%).

This is transferred to an extrusion molding machine and molded to obtain a molded wet cake having a particle size of 8 mmφ.

This shaped wet cake is continuously fed to a single-stage band dryer and dried by forcing hot air at 80-110° C. through it.

At this time, the passage time is adjusted so that the water content is 35-45%. A molded pigment with a water content of 40% was obtained.

Using this molded pigment, a water-based flexographic printing ink color development test was conducted in the same manner as in Example 2. The results are shown in Table-2.

Table 2 *) Pigments normally dried using the same wet cake in the same drying machine (moisture content 1.5%) **) Wet cake (moisture content 70%) used as is.

Example 4 In Example 3, except that barium chloride was used instead of strontium chloride, the same procedure was repeated as in Example 3 to obtain an excellent molded pigment having a water content of 40%.

Example 5 Sodium 5-methyl-4-chloroaniline-2-sulfonate was coupled as a diazo component and β-naphthol as a coupling component in an aqueous solvent, barium chloride was then added, filtered, and washed with water. A wet cake was obtained, which was passed through an extruder to obtain a molded wet cake with a water content of 68% and a particle size of gmmφ.

Using this molded pigment, a powder pigment, and a wet cake for comparison, an offset printing ink was prepared as described below, and a comparative test was conducted by spreading the ink. The results are shown in Table 3.

■) Ink using powder pigment Using the same wet cake, powder pigment (water content 15%) obtained by drying normally in the same dry smoke machine was kneaded with offset resin varnish using three rolls. Make it into ink and spread it on paper.

(2) Ink using the molded pigment of Example 5 After kneading the molded pigment with a resin varnish for offset, vacuum dehydration is performed, the mixture is briefly passed through three rolls to form an ink, and the color is spread on paper.

■) Ink using a wet cake After kneading the wet cake (water content 68%) with the resin varnish for offset, and draining the separated water, vacuum dehydration is performed, and it is easily passed through three rolls. Make it into ink and spread it on paper.

Example 6 Crude stable copper phthalocyanine (purity 95%)
), sodium chloride and ethylene glycol, kneaded and crushed, 5% sulfuric acid aqueous solution was added, filtered and washed with water, and the resulting wet cake was passed through an extruder to form a mixture with a water content of 60% and a particle size of 6 mmφ. A molded wet cake was obtained.

This is continuously supplied to a single-stage band dryer (90-110 tons) for dry explosion.

At this time, the passage time is adjusted so that the water content is 35-45%. A molded pigment with a water content of 40% was obtained.

This molded pigment is excellent for use in aqueous flexographic printing inks and offset printing inks.

Example 7 Crude dioxazine violet (C, r,
Pigment Violet 23), sodium chloride, and diethylene glycol are kneaded and ground, then a 5% aqueous sulfuric acid solution is added, filtered, and washed with water. The obtained wet cake is passed through an extruder to obtain a molded wet cake having a moisture content of 65% and a particle size of 6 mmφ.

This molded wet cake is processed using a single-stage bundt dry machine (80-1).
00℃) and dry smoke.

The passage time is adjusted so that the moisture content is about 35-45%. A molded pigment with a water content of 40% was obtained.

This shaped pigment is excellent for printing inks.

(helmet)

Claims (6)

[Claims] (1) The moisture content of the organic pigment wet cake is 20-55% by weight.
A molded pigment for printing ink characterized by: (2) The molding pigment for printing ink according to claim 1, which is used for water-based flexographic printing ink. (3) The molded pigment for printing ink according to claim 1, which is used for offset printing ink. (4) The shaped pigment for printing ink according to claims 1 to 3, wherein the shaped pigment has a granular shape with a particle size of 1 to 50 mmφ. (5) The shape of the molded pigment is 1-30 mm in thickness and 1- in length.
Claims 1 to 4 are rod-shaped with a diameter of 30 mm.
Molding pigments for printing inks as described in . (6) The molded pigment for printing ink according to claims 1 to 5, wherein the moisture content of the wet cake is 30 to 50% by weight.