JPH0719078B2 - Toner for electrostatic charge development - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a dry toner for developing an electrostatic latent image in electrophotography, a laser printer, ionography and the like.

(Prior Art) Toners used in copiers, laser printers, etc. are kneaded with various additives such as a binder resin, a colorant and a charge control agent, and pulverized to a particle size of about 1 to 30 μm. The particles are fine particles and are used as a two-component developer mixed with a simple substance (carrier) such as glass beads.

In the past, black toner dominated most of the demand, but in recent years, due to diversification of purposes of use, color toners of various hues have been demanded. And in order to respond to this diversification, if one pigment is used,
In many cases, it is difficult to obtain the desired hue, and there are cases in which two or more pigments are used in combination.

However, the toner using two or more pigments in combination often causes a remarkable image defect called "background fog" in the copy / printed matter, as compared with the toner using one pigment. Further, there is a problem in that toner is scattered inside the machine to cause contamination inside and outside the copying machine.

The reason for this phenomenon is considered to be that each pigment imparts the triboelectric charge characteristic of the pigment to the toner, and the combined use of two or more pigments spreads the charge distribution of the toner, and In some cases, it was found that positively and negatively charged toner may be present. It is considered that this is because when the dry pigment is used for kneading, if the kneading is insufficient, the distribution of each pigment in each toner particle varies.

Therefore, when obtaining a toner of a desired hue, it has been found that not only the hue but also the triboelectric charging characteristics of the pigment used in combination must be paid sufficient attention to, which imposes restrictions on formulation.

(Problems to be Solved by the Invention) The present invention intends to solve the above problems in a toner in which two or more kinds of pigments are used in combination, and to expand the degree of freedom in selecting pigments in the case of using pigments in combination. Is.

[Structure of Invention]

(Means for Solving the Problem) The present invention is based on the novel finding that the above problem can be solved by intimately mixing two or more kinds of pigments in advance. That is, the present invention provides a toner for electrostatic charge development, which comprises a binder resin and a colorant as essential components, wherein a colorant obtained by uniformly wet-mixing at least two kinds of pigments and then drying is used. It is provided.

Examples of the binder resin used in the present invention include polystyrene-based resins, copolymer systems containing styrene with styrene and acrylic acid ester, acrylonitrile, butadiene, maleic acid ester, etc., polyacrylic acid ester-based resins, polyester-based resins, polyvinyl ethers. Examples thereof include known thermoplastic binder resins such as resins, polyamide resins, epoxy resins, polyvinyl ketone resins, polyvinyl acetate resins, hydrocarbon resins, petroleum resins, chlorinated paraffin, and pressure fixing. As binder resin for toner for use, low molecular weight polypropylene, low molecular weight polyethylene,
There are ethylene / vinyl acetate copolymers, ethylene / acrylic acid ester copolymers, higher fatty acids, polyamide resins and polyester resins with a low softening point, etc. it can.

The pigments include inorganic pigments such as titanium white, carbon black, navy blue, iron black, red iron oxide, and titanium yellow, azo-based, lake-based, isoindolinone-based, anthraquinone-based, perylene-based, perinone-based, phthalocyanine-based, quinacridone-based, thioindigo Examples include various organic pigments such as pigments.

The wet mixing is performed by kneading and mixing in water or an organic solvent, preferably using a dispersing machine such as a ball mill, a sand mill, an attritor, a kneader, or a roll mill. In this case, as the pigment to be used, a pigment in a wet state before the drying step in the pigment manufacturing process, for example, after coupling of an azo pigment, or a crude pigment such as phthalocyanine or quinacridone is subjected to a solvent treatment or a wet milling treatment. It is preferable to use a paste or slurry which has been filtered and washed with water by a conventional method after being pigmented by. These paste-like or slurry-like pigments are in the state of primary particles without aggregation due to the drying process,
If such pigments are used, they may simply be mixed. In addition, it is preferable that all of the two or more pigments have such primary particles, but for example, if at least one of the two pigments has the primary particles, both are uniformly wet mixed. It

These wet mixed pigments are dried by a conventional method,
Although the pigment composition is intimately mixed, it may be surface-treated with rosin, a rosin derivative, a resin or the like before or after drying. These surface treatments narrow the charge distribution and at the same time facilitate the dispersion of the pigment in the binder resin.

In the present invention, a release agent, an offset improver, a charge control agent, a fluidity improver, a cleaning improver, etc., such as various waxes, low molecular olefins, preferably a melting point.
Depending on the purpose, polyethylene, polypropylene, dyes, hydrophobic silica, fatty acid metal salts, etc. at 80 to 200 ° C can be added according to the purpose.

Hereinafter, the present invention will be specifically described with reference to specific examples. In the examples, parts and% indicate parts by weight and% by weight.

[Preparation of pigment]

Example 1 (Preparation of yellow pigment) (1) Coupling according to a conventional method to give CI Pigment Yellow
Make 14 aqueous slurries.

(2) After filtering the aqueous slurry of (1) and washing with water, water is added to dilute the pigment content to 5% and sufficiently disperse with a high speed dissolver.

(3) The slurry after washing with water in (2) is dried by an ordinary method to obtain an unpulverized lump of pigment.

Example 2 (Preparation of blue pigment) (4) Crude copper phthalocyanine, sodium chloride and polyethylene glycol are kneaded in a kneader and then treated with warm water to prepare an aqueous slurry of CI Pigment Blue 15: 3.

(5) After filtering the aqueous slurry of (4) and washing with water, water is added to dilute the pigment to 5%, and the pigment is sufficiently dispersed with a high-speed dissolver.

(6) The unwashed lump of pigment is obtained by drying the slurry of (5) after washing with water by a conventional method.

Example 3 (Preparation of Red Pigment) (7) Coupling by the conventional method to prepare CI Pigment Red 4
Make an 8: 1 aqueous slurry.

(8) After the aqueous slurry of (7) is filtered and washed with water, water is added to dilute it to a pigment content of 5% and sufficiently dispersed with a high speed dissolver.

(9) The unwashed slurry of pigment is obtained by drying the slurry after washing with water in (8) by a conventional method.

Example 4 (Preparation of mixed green pigment) 1400 parts of the yellow pigment slurry obtained in (2) and 600 parts of the blue pigment slurry obtained in (4) were thoroughly stirred until a uniform mixed slurry was obtained, and the mixture was filtered. , Dry and pulverize to obtain 100 parts of green pigment (A).

Example 5 (Preparation of mixed green pigment treated with rosin) 2000 parts of the mixed slurry obtained in the same manner as in Example 4 was adjusted to pH 9, and then 10 parts of hydrogenated rosin (Stevelite resin manufactured by Hercules) dissolved in an aqueous sodium hydroxide solution was used. Then, after insolubilizing with barium chloride, 112 parts of a green pigment (B) surface-treated by filtration, washing with water, drying and crushing is obtained.

Example 6 In place of 10 parts of hydrogenated rosin in Example 5, 20 parts of tall oil rosin (Silver Roth 80 made by Silver Chemical) and 121 parts of green pigment (C) are obtained in the same manner except that barium chloride is replaced by calcium chloride. .

Example 7 To 2000 parts of a mixed slurry obtained in the same manner as in Example 4, 5 parts of rosin ester (ester gum AT manufactured by Arakawa Chemical Co., Ltd.) was dissolved in 5 parts of xylene, and then the nonionic activator Tohore N220 was used.
(Toho Chemical Co., Ltd.) 0.2 parts and 50 parts of water were added and sufficiently stirred to form a uniform emulsion, which was added to the water dispersion before filtration obtained in Example 4 and heated to 80 ° C., then filtered, washed with water, Dry to obtain 105 parts of green pigment (D).

Example 8 (Comparative Green Pigment) 70 parts of the yellow pigment mass obtained in (3) and 30 parts of the blue pigment mass obtained in (6) were mixed and ground in a hammer mill type grinder to obtain a green color. A pigment (E) is obtained.

Example 9 (Preparation of brown pigment) 1160 parts of the yellow pigment slurry obtained in (2) and 800 parts of the red pigment slurry obtained in (8) were sufficiently stirred until they became a uniform mixed slurry, and filtered, Dry and pulverize to obtain 98 parts of brown pigment (F).

Example 10 (Preparation of rosin-treated mixed brown pigment) 1960 parts of the mixed slurry obtained in the same manner as in Example 7 was adjusted to PH9, and then 15 parts of tall oil rosin dissolved in an aqueous sodium hydroxide solution was added to insolubilize it with strontium sulfate. After filtration, washing with water, drying and pulverization, 113 parts of a brown pigment (G) is obtained.

Example 11 1960 parts of the mixed slurry obtained in the same manner as in Example 7 was adjusted to pH 9, and then 12 parts of disproportionated rosin (Longis R manufactured by Arakawa Chemical Co., Ltd.) dissolved in an aqueous solution of sodium hydroxide was added and the solution was insolubilized with an aqueous laurylamine solution. After filtering, washing with water, drying and pulverizing, 118 parts of a brown pigment (H) was obtained.

Example 12 (brown pigment for comparison) 58 parts of the lump of yellow pigment obtained in (3) and 40 parts of the lump of red pigment obtained in (9) were mixed and ground with a hammer mill type grinder to give a brown powder. A pigment (I) is obtained.

Example 13 (Preparation of mixed pigment of titanium white and blue pigment) 1000 parts of the blue pigment slurry obtained in (5) was mixed with titanium white (Taipaque R-820, trade name of Ishihara Sangyo Co., Ltd.) 5
Parts were added, sufficiently stirred with a high speed dissolver until a uniform mixed slurry was obtained, filtered, dried and pulverized to obtain 55 parts of blue pigment (J).

Example 14 A mass of the blue pigment obtained in (6) was crushed with a hammer mill type crusher, and 50 parts of powder pigment and 5 parts of TYPAKE R-820 were thoroughly kneaded together with 275 parts of water in an attritor.
After filtration, drying and pulverization, 55 parts of a blue pigment (K) was obtained.

Example 15 (Preparation of a mixed pigment of titanium white and a blue pigment for comparison) 50 parts of a mass of the blue pigment obtained in (6) and Typake R-820
5 parts were mixed and pulverized with a hammer mill type pulverizer to obtain a blue pigment (L).

Example 1 Styrene / butyl acrylate copolymer (composition ratio is 85: 1
5) 100 parts (softening point 125 ° C) and the green pigment (A) obtained in Example 4
6 parts, VISCOL 550P (low molecular weight polypropylene: manufactured by Sanyo Kasei Co., Ltd.) 3 parts, quaternary ammonium salt positive charge control agent 2 parts were sufficiently melted and kneaded by a kneading machine, and after cooling, coarsely powdered by a hammer mill, and further The toner was finely pulverized with a jet mill, and a toner having an average particle diameter of 12 μm was obtained with a classifier.

Using a developer consisting of 2 parts of this toner and 100 parts of iron powder carrier, a commercially available copying machine was remodeled, and an image test was conducted 10,000 times with a copying machine using an organic photoconductive photoreceptor as a photoreceptor. It was

The obtained toner image had no fog and a clear green copy was obtained. Also, toner scattering, which is the cause of dirt inside the machine,
The toner was good without spilling.

Comparative Examples 1 to 2 Toners were obtained in the same manner as in Example 1, except that the pigments shown in Table 1 were used instead of the green pigment (A).

As a result of performing the same test as in Example 1 using these toners, toner scattering and toner spillage caused by the spread of the charge amount distribution were observed.

Examples 2 to 9 In Example 1, the results of the charge amount, the image test and the like when using the toners using various pigments are summarized in Table 1 including Example 1 and Comparative Examples 1 and 2.

Examples 10 to 18 Various examples were made in the same manner as in Example 1, except that polyester (KTR2150 manufactured by Kao Corporation) was used as the binder resin and Bontron E-84 (manufactured by Orient Chemical) was used as the charge control agent. As a result of a test using the toner obtained by using the colorant, the same good copy as in Example 1 was obtained, and there was no toner scattering and no toner spilling and it was good.

Comparative Examples 3 to 5 In the same manner as in Example 10, using the toners containing the pigments shown in Table 2 instead of the green pigment (A), the same test results show that the toner scattering caused by the spread of the charge amount is also generated. The toner spill was observed.

The results of the charge amount and image test of Examples 10 to 18 and Comparative Examples 3 to 5 are summarized in Table 2.

Continuation of the front page (56) Reference JP-A-51-82626 (JP, A) JP-A-59-219756 (JP, A) JP-A 61-7844 (JP, A) JP-A 61-118759 (JP , A)

Claims (2)

[Claims] 1. In a toner for electrostatic charge development, which comprises a binder resin and a colorant as essential components, it is preferable to use a colorant which is obtained by uniformly wet-mixing at least two kinds of pigments which are primary particles and then drying. Characteristic toner. 2. The pigment according to claim 1, which is used in a wet state before a drying step in a pigment manufacturing step.
The toner according to the item.