JPH0745633B2 - Colorant manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a colorant used in liquid developers for electrophotography, paints, printing inks and the like.

2. Description of the Related Art Electrons that are uniformly dispersed in a carrier liquid having high insulation and low dielectric constant using a colorant obtained by kneading an organic or inorganic pigment such as carbon black or phthalocyanine blue with a resin and pulverizing the resin as a toner. Liquid photographic developers have long been well known. However, since this colorant usually causes strong secondary aggregation of organic or inorganic pigments, it cannot be easily dispersed into primary particles even if dispersed in a vehicle with a ball mill, attritor, hot roll mill, or the like. there were.

By the way, a flushing method is known in which carbon black or the like is dispersed in water, and then the water surrounding the carbon black is kneaded with the resin solution to replace the water with the resin solution, and then the colorant is produced by removing the water and the solvent. Has been.

However, even with this flushing method, since carbon black is not hydrophilic, it is not well dispersed in water and cannot be atomized.

When a colorant produced by using such a conventional flushing method is used as an electrophotographic toner particle and used in a liquid developer for electrophotography, the dispersibility in a carrier liquid is not sufficient, and therefore, a high density gradation is obtained. It was difficult to form an image excellent in fixing property and fixing property.

However, (a) when dispersing a colorant such as carbon black in water, an anionic, nonionic or cationic surfactant or a high molecular synthetic polymer dispersant is used to improve the method for producing a colorant employing such a flushing method. Etc., (b) Dispersing a colorant such as carbon black using humic acid, a humic acid salt or a humic acid derivative,
Furthermore, a method for coating pigment particles by kneading low-molecular-weight polyethylene or natural resin-modified resin, dammal, copal, shellac, gum rosin, styrene-butadiene copolymer, polyolefin, etc. (Japanese Patent Laid-Open No. 59-102253), etc. It is disclosed.

However, the colorant obtained by the above method (a) has a drawback that the dispersibility in the carrier liquid is still insufficient. Further, the colorant obtained by the above method (b) cannot be said to be sufficiently blended with other resins, and therefore has a drawback that the adherence is slightly inferior.

Object The present invention provides a colorant for use in electrophotographic toners, dyes, printing inks, etc. which can be particularly well fixed and adhered to paper, wood, metal plates and the like.

Structure The method for producing a colorant of the present invention is a flushing method in which at least (1) a pigment and (2) an ethylene-vinyl acetate copolymer are further contained, and further (3) a humic acid, a humic acid salt or a humic acid derivative is contained. It is characterized by performing by the method.

Incidentally, in the pigment dispersion using the pigment and the ethylene-vinyl acetate copolymer or the pigment dispersion using the pigment, humic acid (humic acid salt, humic acid derivative) and the ethylene-vinyl acetate copolymer, Since the compatibility with other resins and the melt viscosity at the time of heating and kneading are high, not only the dispersion of the pigment itself but also the dispersion of the obtained colorant and the blending with other resins become easy. Found.
The present invention has been completed based on such knowledge.

The present invention will be described in more detail below.

First, the pigment used in the present invention (carbon black,
Examples of organic pigments include the following.

As carbon black, any of furnace black, acetylene black, channel black and the like can be used. Commercially available products such as Printex G, special black 15, special black 4 and special black 4-
B (above Degussa), Mitsubishi # 44, # 30, MA-11, MA-100
(Made by Mitsubishi Carbon Co., Ltd.), Raven 30, Raven 40,
Conductex SC (made by Columbia Carbon Co., Ltd.),
Regal 800, 400, 660 and Black Pearl L (all manufactured by Cabot Corporation) are known.

Examples of organic pigments include phthalocyanine blue, phthalocyanine green, sky blue, rhodamine lake, malachite green lake, methyl violet lake, peacock blue lake, naphthol green B, naphthol green Y, naphthol yellow S, lysol farst yellow 2G, permanent red 4R. , Brilliant Huast Scarlet, Hansa Yellow, Benzidine Yellow, Resole Red, Lake Red C, Lake Red D, Brilliant Carmine 6B, Permanent Red
Examples include F5R, Pigment Scarlet 3B and Bordeaux 10B.

The resin coating the pigment is preferably slightly soluble or insoluble in the non-aqueous solvent (the carrier liquid in the case of an electrophotographic liquid developer). In the present invention, an ethylene-vinyl acetate copolymer is adopted as this. ing.

The ethylene-vinyl acetate copolymer has a vinyl acetate content of 1.
It is desirable that the content thereof is 0 to 50% by weight, preferably 10 to 40% by weight, and the softening point is in the range of 40 to 180 ° C, preferably 60 to 120 ° C. Typical examples (commercially available products) of such ethylene-vinyl acetate copolymer are as follows. (I) Made by Mitsui DuPont Polychemicals (Ii) manufactured by Toyo Soda (Iii) Made by Allied Chemicals (Iv) Made by Hoechst (V) Made by BASF The amount of these ethylene-vinyl acetate copolymers used is pigment 1
0.01 to 3.0 parts by weight, preferably 0.1 to 2.0 parts by weight, is suitable for the parts by weight.

In addition, a part of the ethylene-vinyl acetate copolymer is, for example, natural resin-modified coal resin, natural resin-modified maleic acid resin, dammar, copal, shellac, gum rosin, cured rosin, ester gum glycerin ester-modified maleic acid resin, styrene. -It is possible to partially substitute a butadiene copolymer, a polyolefin, a copolymer with a polyolefin, or a wax.

Here, examples of commercially available products of the above resins (including waxes) other than the ethylene-vinyl acetate copolymer include the following.

One of the present invention is a colorant in which a pigment is coated with a specific resin,
Although obtained by the flushing method, another of the present invention is obtained by further using humic acid, a humic acid salt or a humic acid derivative during the pigment dispersion process.

Explaining humic acid, humic acid is an alkali-soluble amorphous polymeric organic acid contained in young coals such as peat and lignite having a low degree of coalification. This humic acid is roughly classified into a natural product and an artificial product (including nitrofunic acid), and any of them can be used in the present invention. Industrial products of humic acid are
There are CH type, CHA type and CHN type depending on the difference in molecular weight distribution.
There are acid type and salt type such as Na, NH _4, etc., and any of them can be used.

Humic acid, humic acid salts, or humic acid derivatives (hereinafter referred to as "humic acids") are well adsorbed on pigments, and are therefore more advantageous for finely dispersing to the order of primary particles and improving dispersion stability (long-term storage). .

The colorant is manufactured using the above raw materials as follows. Humic acids were mixed in the pigment-containing liquid with 0.1 to 30% by weight of the pigment-containing liquid and mixed well in a kneader, or a pigment-containing liquid containing no humic acids was further added to a resin solution in a kneader called a flasher. Mix well. This replaces the water present in the pigment surround with the resin solution. Water is discarded from the kneader, and the pigment solution dispersed in the resin solution is dried to remove the solvent to obtain a lump. Then, the lump is crushed to obtain a colorant powder. This colorant is a pigment coated with resin in the form of primary particles and is useful for printing ink, paint, toner for electrostatic photography, and the like.

For example, in order to prepare a liquid developer for electrostatic photography using the colorant produced as described above, this colorant may be dispersed in a carrier liquid together with a binder resin.

The carrier liquid has high insulation (electrical resistance 10 ¹⁰ Ωcm or more),
Petroleum-based aliphatic hydrocarbons with low dielectric constant (dielectric constant of 3 or less), n-
Hexane, ligroin, n-heptane, n-pentane, isododecane, isooctane, and other halogen derivatives thereof such as carbon tetrachloride and perchlorethylene can be mentioned. Commercial products of the above-mentioned petroleum-based aliphatic hydrocarbons are Ansoper E, Isopar G, Isopar L, Isopar H, Isopar K, Naphtha No.
There are 6 and Solvesso 100. These are used alone or in combination.

Next, examples and comparative examples will be shown.

Example 1 Water 500 g Printex 30 g Alkane blue 20 g Humic acid 10 g was thoroughly stirred with a flasher, and then 600 g of an ethylene-vinyl acetate copolymer (Evaflex 310) was added to the flasher and kneaded. Subsequently, the mixture was heated and decompressed to remove water and solvent, and a lump of the coloring agent having a water content of 0.50% was obtained. This was pulverized with a stone mill to obtain a powder having a size of 1 to 5 μ.

Examples 2 to 10 In the same manner as in Example 1, except that the raw materials were changed to those shown in Table-1, nine kinds of colorant powders were produced.

A colorant powder was produced in the same manner as in Example 5 or 6 except that all of the humic acid salts were replaced with phthalocyanine blue or alkali blue, but these also showed good fixability and image density.

Comparative Examples 1-10 Ten types of comparative colorant powders were prepared in a manner corresponding to Examples 1-10. However, ethylene-
The vinyl acetate copolymer was not used, and those shown in Table 2 were used.

In addition, 20 g of these colorant powders together with 50 g of polylauryl methacrylate / acrylic acid (90/10) are used as isopar
G was added to 100 g and kneaded with a ball mill for 72 hours to give a concentrated toner, and 50 g of this was dispersed in 2 l of Isopar H to prepare a developer.

The results shown in Table 3 were obtained by using these developers for copying with a commercially available copying machine (Recopy DT-1200, manufactured by Ricoh Co., Ltd.).

Effect The colorant produced by the method of the present invention, as described above,
It has good fixing performance. Further, especially when carbon black is used as the pigment, the blackness is further increased, which is due to the flaming colorant of the present invention.
It is considered that this indicates that the carbon black is well dispersed.

Continuation of the front page (56) Reference JP-A-59-100168 (JP, A) JP-A-54-95633 (JP, A) JP-A-58-17169 (JP, A)

Claims (2)

[Claims] 1. A method for producing a colorant, which comprises producing at least (1) a pigment and (2) an ethylene-vinyl acetate copolymer in the production of the colorant using a flushing method. 2. A method for producing a colorant using a flushing method, which comprises at least (1) a pigment, (2) humic acid, a humic acid salt or a humic acid derivative, and (3) an ethylene-vinyl acetate copolymer. A method for producing a colorant, comprising: