JPH0735490B2 - Easy dispersible pigment composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to suitability for use of pigments. More specifically, the present invention relates to a pigment and a method of using the same for providing a gravure ink and a flexo ink having good flow characteristics and high gloss under weak dispersion conditions.

(Prior Art) Generally, a practically useful pigment that exhibits high gloss and high tinting strength in various coating compositions is composed of fine particles. Conventionally, when dispersing pigments, which are agglomerates of fine primary particles, in vehicles such as paints and gravure ink, it is necessary to apply strong force for a long time to disperse the agglomeration of particles, and to promote the dispersion. A method of adding a dispersion material is known. For example, a ball mill or a sand mill takes a long time to disperse the particles, or the method disclosed in JP-A-59-96
A method of adding a pigment derivative as seen in JP-A No. 175, a method of adding a dispersion resin as seen in JP-A-57-74330, and the like. However, none of the methods was fully satisfactory.

(Problems to be Solved by the Invention) Practically excellent pigments for high-gloss gravure inks or flexo inks that do not require strong dispersive power have been demanded.

[Structure of Invention]

(Means for Solving the Problem) As a result of various investigations for solving the above problems, the present inventors have found that coarse pigment pigments provide a high-gloss gravure ink or flexo ink under weak dispersion conditions, and The present invention has been completed by finding that the addition of an organic dye derivative brings out the effect of improving the fluidity and gloss more effectively than before.

That is, the present invention does not substantially include agglomerates having a particle diameter of 10 mm or more, and particles of 0.175 (80 mesh) to 5 mm (4 mesh) are
0% by weight or more of an organic pigment and 0.1 to the pigment
An easily dispersible pigment composition for gravure inks or flexographic inks containing 30% by weight of an organic dye derivative.

The pigment in the present invention can be manufactured by two methods. The first method is to pulverize dried pigment mass (water content 2% or less) with a coarse pulverizer, and the second method is
The wet cake is formed into a shape that is easy to dry and then dried.

In the first method, the pigment lump is a pigment lump obtained by drying a press cake of the pigment with a box dryer, a band dryer, etc., and most of it is a lump of 10 mm or more. There are cutter mills, knife hammer mills, roll mills, etc. as coarse crushers, but it is necessary to examine the operating conditions in order to contain more than 40% by weight of particles of 0.175 to 5 mm.
It is difficult to efficiently grind particles of 0.175 to 5 mm of the present invention with a hammer mill widely used for general grinding.

In the second method, extrusion molding, pump extrusion molding, groove drum molding and the like are methods for molding the wet cake into a shape that is easy to dry. For drying the formed wet cake, a box dryer or band dryer is used.

As for the particle size, the larger the particle size of the pigment, the higher the gloss, but almost no improvement in gloss can be seen at 5 mm or more, and if it is 10 mm or more, it may cause clogging or poor dispersion when introduced into the disperser. is there. At 40% by weight or less of particles of 0.175 mm or more (on 80 mesh sieve), there is no great difference from the conventional product crushed by a hammer mill (10% or less of particles of 0.175 mm or more). Although it is preferable that the particle size distribution range is small, it is difficult to efficiently produce a pigment with a particle size of 0.175 to 5 mm of 70% by weight or more with a coarse pulverizer, and the quality becomes unstable. easy. When the wet cake is dried, the distribution width is small, and particles of 0.175 to 5 mm are generally 80% by weight or more of the pigment.

As the pigment, all known organic pigments such as phthalocyanine type, quinacridone type, dioxazine type, azo type and disazo type can be applied.

As the organic dye derivative, a well-known organic dye derivative represented by the following general formula is used.

General formula [In the formula, A represents an organic dye residue, and B _{1 to} B ₄ are hydrogen atoms (excluding cases where all are hydrogen atoms) or substituents represented by the following (a) to (g). .

(Wherein, X represents a hydrogen atom, a halogen atom, -SO ₃ H, an integer of -NO ₂ or -NH _2, l = 1~2.) (In the formula, X and l are the same as the above. M is a hydrogen atom, Al, Ca, Ba or Sr, m is the valence of M.) (c) -SO ₃ M / m (wherein M, M, m is the same as above.) (d) -COOM / m (wherein M and m are the same as above). (Wherein, Y is _{-SO 2 NC -, - CH 2} NH - CONH- or -CH ₂ N
A linking group selected from HCOCH ₂ NH-, R ₁ and R ₂ are hydrogen atoms, an alkyl group having 1 to 4 carbon atoms, or those that form a heterocycle with R ₁ and R ₂ , n is an integer of 2 to 8 Show. ) (In the formula, R ₁ and R ₂ are the same as above.) (In the formula, R ₁ and R ₂ are the same as above. R ₃ and R ₄ represent a hydrogen atom or an alkyl group, and the sum of carbon numbers of R _{1 to} R ₄ is 10 to 40.)] Organic dye residue The group generally has the same or similar structure as the pigment used, but may have a completely different structure.

The amount of organic pigment derivative added is 99.9 to 70% by weight of coarse particle pigment.
With respect to the organic dye derivative 0.1 to 30% by weight, preferably 0.3
~ 10% by weight. If it is less than 0.1% by weight, the effect of improving the fluidity is insufficient, and if it is more than 30% by weight, the effect of using more is not obtained.

The method for adding the organic dye derivative is not particularly limited, and it may be added at the time of synthesizing the pigment or at the time of forming the pigment, a method at the time of slurry before producing coarse particles of the pigment, a dry mixing method, etc. In this method, a coarse particle pigment is dry-mixed with a coarse particle organic dye derivative.

The pigment obtained in the present invention is dispersed in various vehicles by a dispersing machine such as a ball mill, a sand mill, or an attritor to be made into an ink, and a high-gloss gravure ink or flexo ink can be obtained in a shorter time than conventional pigments. .

(Operation) Although the operation mechanism of the present invention is not well understood, it is related to dispersion in a dispersion medium having a relatively low solid content such as gravure ink or flexo ink, and to a dispersing machine by impact force such as a ball mill. I think that the. In other words, the coarsely pulverized pigment of the present invention cannot be used in a system using a dispersing machine with shearing force such as a roll mill in a dispersion medium having a high solid content and high viscosity such as plastics and offset ink.

(Effect) By using the easily dispersible pigment of the present invention, a high-gloss gravure ink having good fluidity with a shorter dispersion time than the conventional one,
And flexo ink can be obtained.

The outline of the method for producing the easily dispersible pigment of the present invention is described below with reference to Examples
A comparative example will be described. In the examples, "part" and "%" mean "part by weight" and "% by weight", respectively.

[Production Example 1] A mixture of 97 parts of a dry mass of copper phthalocyanine pigment (CI Pigment Blue 15: 3) (5% or less of particles of 10 mm or less) and 3 parts of the organic dye derivative (a) of Table 1 was cut with a cutter mill ( 97 parts of coarsely pulverized pigment was obtained under the conditions of 1300 rpm and 3 mm screen. Particle size distribution is 4 mesh (opening is 4.
8 mm), 18 mesh (1.0 mm), 80 mesh (0.175 mm) When measured using a wire mesh, 4.8 mm or more 0%, 4.8 ~ 1.0 m
m was 3.6%, 1.0 to 0.175 mm was 49.5%, 0.175 mm or less was 46.9%.

[Production Examples 2 to 5] In the same manner as in Production Example 1, the organic dye derivatives shown in Table 1 were mixed and produced with a cutter mill. Table 1 shows the pigment name, the structure of the organic dye derivative, the amount added, and the particle size distribution.

[Production Example 6] Copper phthalocyanine pigment (CI Pigment Blue 15: 1) 9
5 parts and 5 parts of the organic dye derivative (b) were ground by a roll mill to obtain a coarsely ground pigment. The particle size distribution is shown in Table 1.

[Production Example 7] A wet cake (water content 60%) consisting of CI Pigment Blue 15: 3 92% and organic pigment derivative (c) 8% was molded into a rod shape by an extrusion molding machine (screen diameter 2 mm) and box-dried. Machine dried. Particle size distribution is 4.8 mm or more 0%, 4.8 to 1.0 mm
Was 83.6%, 1.0-0.175 mm was 6.2%, 0.175 mm or less was 10.2%.

[Example 1] 20 parts of the pigment of Production Example 1, 45 parts of lime rosin varnish for publication gravure ink, and 35 parts of toluene were dispersed by a ball mill for 8 hours.

Example 2 15 parts of the pigment of Production Example 2 and 85 parts of nitrocellulose varnish for flexo ink (solid content 17%, ethyl acetate 10%, dioctyl phthalate 5%, methanol 68%) were placed in a ball mill 8
Time dispersed.

Example 3 10 parts of the pigment of Production Example 3, 45 parts of polyamide-nitrocellulose varnish, and 30 parts of an organic solvent (toluene / ethyl acetate / isopropyl alcohol) were dispersed in a ball mill for 8 hours.

[Examples 4 to 6] 10 parts of the pigments of Production Examples 4 to 6, 70 parts of nitrocellulose varnish for packaging gravure ink, and 20 parts of an organic solvent (toluene / ethyl acetate / isopropyl alcohol) were dispersed in a ball mill for 8 hours.

[Examples 7 and 8] 10 parts of the pigment of Production Example 7 or 4, 60 parts of cyclized rubber varnish, and 30 parts of toluene were dispersed by a ball mill for 8 hours.

[Comparative Example 1] The same pigment mass and organic pigment derivative as those used in Production Example 1 were crushed with a hammer mill (0.175 mm).
The above particles were dispersed under the same conditions as in Example 1 using 10% or less).

[Comparative Example 2] The pigment mass of Production Example 1 was roughly pulverized without adding the organic dye derivative and dispersed under the same conditions as in Example 1.

[Comparative Example 3] A pigment obtained by grinding the same pigment mass as that used in Production Example 1 with a hammer mill without adding an organic dye derivative (0.
10% or less of particles having a size of 175 mm or more) were dispersed under the same conditions as in Example 1.

[Comparative Examples 4 to 10] As shown in Table 3, pigments obtained by crushing the same pigment lumps and organic dye derivatives as those used in Production Examples by a hammer mill (both particles having a diameter of 0.175 mm or more are 10% or less). Were dispersed under the same conditions as in Examples 2 to 8.

The inks obtained in Examples 1 to 8 and Comparative Examples 1 to 10 were color-developed on a triacetate film, and the gloss value was measured with a digital variable angle gloss meter (manufactured by Suga Test Instruments). The viscosities of the inks obtained in Examples 1-8 and Comparative Examples 1-10 were measured with a BM type viscometer. The results are shown in Table 3.

Claims (5)

[Claims] 1. Substantially free of lumps having a particle size of 10 mm or more,
An easily dispersible pigment composition for gravure inks or flexo inks, characterized in that the particles of 0.175 to 5 mm contain 40% by weight or more of an organic pigment and 0.1 to 30% by weight of the organic pigment derivative with respect to the pigment. 2. An organic pigment obtained by crushing a lump having a water content of 2% by weight or less with a coarse crusher, wherein particles having a particle diameter of 0.25 to 1 mm are 40
The easily dispersible pigment composition according to claim 1, wherein the easily dispersible pigment composition is at least wt%. 3. A pigment of which the wet cake is formed into a shape which is easy to dry, and then dried to a water content of 2% by weight or less, 0.175 to 5 mm.
The easily dispersible pigment composition according to claim 1, which is an organic pigment having particles of 60% by weight or more. 4. The easily dispersible pigment composition according to any one of claims 1 to 3, wherein the organic pigment is a pigment selected from phthalocyanine type, azo type, quinacridone type, disazo type and dioxazine type. 5. The easily dispersible pigment composition according to any one of claims 1 to 4, wherein the organic dye derivative is represented by the following general formula. General formula [In the formula, A represents an organic dye residue, and B _{1 to} B ₄ are hydrogen atoms (excluding cases where all are hydrogen atoms) or substituents represented by the following (a) to (g). . (Wherein, X represents a hydrogen atom, a halogen atom, -SO ₃ H, an integer of -NO ₂ or -NH _2, l = 1~2.) (In the formula, X and l are the same as the above. M is a hydrogen atom, Al, Ca, Ba or Sr, m is the valence of M.) (c) -SO ₃ M / m (wherein M, M, m is the same as above.) (d) -COOM / m (wherein M and m are the same as above). (In the formula, Y is -SO ₂ NH-, -CH ₂ NH-, -CONH- or -CH
₂ NHCOCH ₂ A linking group selected from NH-, R ₁ and R ₂ are hydrogen atoms, alkyl groups having 1 to 4 carbon atoms, or R ₁ and R ₂ form a heterocycle, n is an integer of 2 to 8 Indicates. ) (In the formula, R ₁ and R ₂ are the same as above.) (In the formula, R ₁ and R ₂ are the same as above. R ₃ and R ₄ represent a hydrogen atom or an alkyl group, and the sum of carbon numbers of R _{1 to} R ₄ is 10 to 40.)]