JP2939455B2 - Toner particles and negatively chargeable cyan toner for electrophotography containing the toner particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner particle for electrophotography and a toner for electrophotography containing the toner particle, and more particularly to a negatively chargeable cyan toner for electrophotography.

[0002]

2. Description of the Related Art As color electrophotographic toners, toners in which various dyes and pigments are dispersed in a binder resin are widely used. Among these color toners, as a cyan toner for electrophotography, those using a phthalocyanine-based organic pigment exhibiting a clear blue color are mainly used. However, since the phthalocyanine-based organic pigment itself has a strong positive charge, when used as a negatively chargeable toner, in a high humidity environment, the charge amount decreases, and the image density changes or fog occurs. And other problems.

In order to improve these points, Japanese Patent Application Laid-Open No. Hei 4-24652 discloses a toner using a phthalocyanine blue pigment whose surface is coated with negatively charged hydrophobic silica. However, these toners
Since the pigment is coated with silica, the coloring property is insufficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a color electrophotographic apparatus which solves the above-mentioned disadvantages of the conventional negatively chargeable cyan toner, has excellent charging characteristics and moisture resistance, and forms a vivid image. To provide a cyan toner for use.

[0005]

The inventors of the present invention have conducted intensive studies on the chargeability of cyan toner using copper phthalocyanine as a coloring agent, and as a result, free copper contained in copper phthalocyanine has an adverse effect on the chargeability of cyan toner. Have been found to have led to the present invention.

That is, the first invention is a toner particle comprising a copper phthalocyanine pigment having a free copper content of 2000 ppm or less and at least a binder resin.

[0007] The second invention is to provide a copper phthalocyanine pigment
The toner particles according to the first invention, wherein the toner particles comprise 10 to 10% by weight.

[0008] A third invention is a negatively chargeable cyan toner for electrophotography, comprising the toner particles according to the first or second invention and at least one external additive.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention, it is important that the content of free copper in the copper phthalocyanine pigment is 2000 ppm or less. Since the free copper remaining as impurities in the copper phthalocyanine pigment is positively charged, the present invention reduces the amount of such free copper present in the pigment, thereby improving the pigment,
This makes it possible to favorably negatively charge the toner particles and the toner containing the pigment, and the content of free copper in the copper phthalocyanine pigment is 2000 pp.
If it is higher than m, the chargeability of the toner is reduced in a humid environment, and image defects such as fog occur.

The copper phthalocyanine pigment is usually prepared by heating phthalic acid or a phthalic acid derivative, urea or a urea derivative and a copper compound in an inert organic solvent in the presence of a phthalocyanine catalyst such as a molybdenum compound to obtain a crude copper phthalocyanine. After that, it is manufactured through a pigmentation process for making it finer. The content of free copper used in the present invention is 200
The copper phthalocyanine pigment of 0 ppm or less is obtained by removing the solvent from the reaction product under reduced pressure after the completion of the heating reaction in the method for producing a copper phthalocyanine, washing the obtained residue sufficiently with water, or After phthalocyanine is obtained, it can be obtained by sufficiently washing it with water or an acid in a pigmentation step of making it finer, and it is preferable to wash it sufficiently in both steps. For example, in the method for producing copper phthalocyanine, after the completion of the heating reaction, the solvent is distilled off from the reaction product under reduced pressure, and the obtained residue is washed with water to reduce the content of free copper to about 12000 ppm. The content of free copper in the pigment finally obtained through a water washing step of pigmentation by a solvent salt milling method or an acid pasting method and an acid washing step of pigmentation by a dry milling method is 2,000 p.
pm or less. Further, in order to further reduce the content of free copper, a method of washing the residue with acid using dilute sulfuric acid or the like, in addition to a molybdenum compound catalyst usually used, a trace amount of a ruthenium compound and / or an osmium compound is used. A method of adding to the reaction system or the like may be used.

The content of free copper is determined as follows. After precisely weighing 3.0 g of a copper phthalocyanine sample, 30.0 g of sulfuric acid is added and dissolved, then added to 150 ml of cold water, and stirred at 90 ° C. for 30 minutes. Next, the precipitate is filtered, and the obtained wet cake is washed with hot water until the washing liquid becomes neutral. Free copper in the filtrate and the washing solution is determined by an atomic absorption method.

The toner particles according to the present invention contain copper phthalocyanine having free copper of 2000 ppm or less and at least a binder resin.
m or less of copper phthalocyanine is preferably contained in the toner particles in an amount of 1 to 10% by weight. 1% by weight pigment content
If it is less than 10% by weight, sufficient coloring power cannot be obtained. On the other hand, if it exceeds 10% by weight, the chargeability of the toner is reduced in a humid environment, and image defects such as fog occur.

Examples of the binder resin used in the present invention include various material resins such as styrene-acrylic and polyester-based resins conventionally known as electrophotographic toner binder resins. In addition, the production method of any resin is not particularly limited.

The toner particles according to the present invention may contain, if necessary, a known charge controlling agent such as a salicylic acid metal complex or a metal-containing azo compound, or an anti-offset agent such as low molecular weight polypropylene, low molecular weight polyethylene or wax. Other components can be added.

In the present invention, the method for producing toner particles is not particularly limited. For example, in order to produce toner particles, for example, the content of free copper obtained by a solvent salt milling method is 2,000 ppm or less The water in the aqueous slurry of the fine particle copper phthalocyanine pigment is removed by a filter to obtain a wet cake. From, kneading with the binder resin, dispersed, after adjusting the resin dispersed pigment, further mixed with the binder resin at a desired ratio, melted and kneaded by a kneader, an extruder or the like, cooled, and then jet mill etc. It can be obtained by pulverizing with a means, and classifying the obtained pulverized product with an air classifier.

The cyan toner for electrophotography of the present invention is obtained by adding a fluidity-imparting agent such as silica or titanium oxide which has been subjected to a hydrophobic treatment with a silane coupling agent or the like as an external additive to the toner particles.

The cyan toner for electrophotography of the present invention obtained as described above can be used as a one-component developer.
Alternatively, it may be used as a two-component developer by mixing with a carrier.

[0018]

The present invention will be described in detail below with reference to examples and comparative examples. However, this does not limit the embodiments of the present invention at all.

Pigment Production Example 1 Crude copper phthalocyanine having a free copper content of 3500 ppm (No. 3 crude blue; manufactured by Toyo Ink Co., Ltd.)
250 parts by weight, together with 1000 parts by weight of dried sodium chloride and 250 parts by weight of diethylene glycol, were charged into a 2 liter test kneader, wet-milled at 100 to 110 ° C. for 4 hours, and the obtained lump was added with 25 g of 10% diluted sulfuric acid to 5 liters. After adding to warm water, stir and add sodium chloride,
After diethylene glycol was completely dissolved, the mixture was filtered and washed with water until dilute sulfuric acid did not remain in the filtrate, and then water was removed with a filter to obtain a wet cake A of a copper phthalocyanine pigment having a water content of 50%. A part of this wet cake was dried and its free copper content was measured.
It was 0 ppm.

Pigment Production Example 2 A wet cake B of a copper phthalocyanine pigment having a water content of 50% was obtained in the same manner as in Pigment Production Example 1, except that dilute sulfuric acid was not added in the pigment washing step. A part of this wet cake was dried and its free copper content was measured.
It was 00 ppm.

Example 1 A polyester resin synthesized from 50 parts by weight of a wet cake A of a copper phthalocyanine pigment obtained in Pigment Production Example 1 and a propylene oxide adduct of bisphenol A and terephthalic acid (Tg: 55 ° C., Mn 3,000, Mw:
25,000) and 50 parts by weight were kneaded in a heating / pressure kneader at 100 to 110 ° C. for 30 minutes. Thereafter, it was taken out of the kneader, cooled, and pulverized to obtain a resin-dispersed pigment A. Next, the above polyester resin 9 is used as a binder resin.
4 parts by weight of the obtained resin-dispersed pigment A was added to 6 parts by weight, preliminarily mixed by a Hensiel mixer, melt-kneaded by a twin-screw extruder, cooled, coarsely ground by using a hammer mill, and then jetted. After finely pulverizing with a mill, the particles were classified with an air classifier to obtain toner particles having an average particle size of 9.5 μm. 0.4 parts by weight of hydrophobic titanium oxide fine powder having an average particle size of 0.05 μm was added as a fluidity improver to 100 parts by weight of the toner particles, and mixed with a Hensiel mixer to obtain a cyan toner.

Comparative Example 1 A cyan toner was obtained in the same manner as in Example 1 except that wet cake A was changed to wet cake B obtained in Pigment Production Example 2.

Measurement of Stability of Charging Humidity 5 parts by weight of each of the above toners was added to 100 parts by weight of a coating carrier obtained by coating a ferrite having a particle size of about 50 μm with a silicone resin to prepare a developer. . Each of these developers was used in a low-temperature and low-humidity environment (1
5 ° C 30% RH) and high temperature and high humidity environment (30 ° C 85% RH)
For 24 hours, and then stirred for 30 minutes with a ball mill, and then the charge amount was measured using a charge amount measuring device manufactured by Toshiba Chemical Corporation. Table 1 shows the results.

Using the toner of Example 1 for image evaluation at low temperature and low humidity and high temperature and high humidity (30 ° C., 85% humidity) using a commercially available full-color copying machine (CLC350; manufactured by Canon Inc.) A good image was obtained without being affected by the image quality. On the other hand, when the same image evaluation was performed using the toner of Comparative Example 1, fog was easily generated at high temperature and high humidity, and the toner was scattered around the developing machine.

[0025]

[Table 1]

[0026]

As described above, the toner particles according to the present invention and the negatively chargeable cyan toner for electrophotography containing the toner particles are hardly influenced by the environment and can obtain an appropriate charge amount even in a humid environment. By using such a negatively chargeable cyan toner for electrophotography, a good image can be obtained.

Claims (3)

(57) [Claims] 1. A toner particle comprising a copper phthalocyanine pigment having a free copper content of 2000 ppm or less and at least a binder resin. 2. A copper phthalocyanine pigment in an amount of 1 to 10% by weight.
The toner particles according to claim 1, wherein the toner particles are contained. 3. A negatively chargeable cyan toner for electrophotography, comprising the toner particles according to claim 1 and at least one external additive.