JP2914050B2 - Positively chargeable magnetic one-component toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic toner for visualizing an electrostatic image such as an electrophotographic method. More specifically, the present invention relates to a positively chargeable magnetic one-component toner that visualizes a negatively charged electrostatic image and provides a high-quality image.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic method, US Pat.
Although many methods are known, such as the specification of No. 297691,
In principle, a photoconductive substance is used to form an electrostatic latent image on the photoreceptor surface by various means, and then developed using an electrostatic toner to form a visible image. Further, if necessary, the image is transferred to a transfer material such as paper, and a fixed image is obtained by applying heat, pressure and the like.

As methods for visualizing an electrostatic latent image, a magnetic brush method (US Pat. No. 2,870,463), a cascade method (US Pat. No. 2,221,776), and a method using a conductive magnetic toner (US Pat. No. 3,909,258). Specification), a method using an insulating magnetic toner (Japanese Patent Publication No. 41-9)
475) have been devised. At present, methods mainly used in practice are a magnetic brush method called a two-component development method and a method using an insulating magnetic toner called a one-component development method.The two-component development method uses toner particles and carrier particles. Due to the mixed developer, the carrier particles deteriorate due to long-term use, and it is necessary to replace the developer. Further, since it is necessary to always maintain the mixing ratio of the toner particles and the carrier particles at a constant level, a technique is required for controlling the toner concentration, and there is a problem that the machine becomes large and complicated. A method devised to solve these problems is a one-component development method using an insulating magnetic toner. Since this method does not require carrier particles, the method does not require replacement of the developer and control of the toner concentration at all, thereby improving the above-mentioned problem.

On the other hand, a selenium-based or cadmium sulfide-based photosensitive member has conventionally been used as a photosensitive member for forming an electrostatic latent image. Since these have positive charging properties, toners for visualizing an electrostatic latent image are mainly of negative charging properties. However, selenium or cadmium sulfide used in this type of photoreceptor has a problem in terms of safety and health for human bodies, and is currently being replaced with a photoreceptor using an organic material. The main organic materials include phthalocyanine-based compounds, which have a negative charge property. Therefore, a positively chargeable toner is used as a toner for visualizing an electrostatic latent image.

[0005] The toner used in the one-component developing method is obtained by dispersing a dye, a pigment, a magnetic powder and the like in a binder resin, and pulverizing and classifying the particles to 1 to 30 µm. It is known that the addition of hydrophobic colloidal silica to this toner improves the prevention of aggregation and the fluidity. However, when dry colloidal silica is added to the positively chargeable toner, the flowability is improved, but the charge amount of the toner is reduced, causing a reduction in image density and a fogging phenomenon, thereby deteriorating the image quality. In order to solve these problems, it has been proposed to add a metal oxide which acts as a charging aid in combination with dry colloidal silica to prevent a reduction in charge amount, that is, a deterioration in image quality. The metal oxide referred to here is aluminum oxide,
Examples include titanium oxide, calcium titanate, magnesium stearate, strontium titanate, magnetite, zinc oxide, and tin oxide.

However, since these conventional metal oxides generally have an irregular shape, the photosensitive member is damaged by the pressure of a blade or a fur brush in a cleaning section for removing residual toner. Further, since the volume average particle size is often 0.1 μm or less, when added to the toner, physical adhesion such as van der Waals force is large. Therefore, it adheres firmly to the toner surface,
As a result, the toner fluidity tends to decrease. This decrease in toner fluidity favorably inhibits the formation of the sleeve layer pressure and leads to a decrease in image density. Therefore, these metal oxides cannot sufficiently compensate for the adverse effects caused by the addition of dry colloidal silica.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner which can prevent a decrease in charge amount and does not cause a decrease in fluidity in a one-component developing method using a positively chargeable toner. And Further, the present invention provides a toner capable of minimizing damage to the photoreceptor and prolonging the life of the photoreceptor and stably obtaining a high-quality image.

[0008]

According to the present invention, there is provided a one-component toner particle having a binder resin, a magnetic powder and a positive charge control agent as main components, and an amorphous calcium oxide having a volume average particle diameter of 0.5 to 10 μm.
The present invention relates to a positively chargeable magnetic one-component toner comprising spherical particles of sodium aluminosilicate and dry colloidal silica. Dry colloidal silica is produced by hydrolyzing silicon tetrachloride gas in a flame of hydrogen and oxygen, and is generally represented by Formula 1.

[0009]

Further, it is known to modify with dimethyldichlorosilane or the like in order to impart hydrophobicity.

The amount of dry colloidal silica added depends on the amount of toner.
The amount is preferably 0.01 to 3 parts by weight, particularly preferably 0.1 to 0.5 part by weight, per 100 parts by weight. If the amount is 0.01 part by weight or less, sufficient fluidity cannot be obtained, and the effects of the present invention cannot be obtained. Also, if it exceeds 3 parts by weight, the fluidity does not increase in proportion to the addition amount, and conversely the cost increases, which is not appropriate. Next, details of the amorphous calcium-sodium-aluminosilicate spherical particles will be described below. Amorphous calcium-sodium-aluminosilicate spherical particles are obtained by treating zeolite with calcium, washing with water,
It is obtained by firing. The method for producing zeolite mainly includes a dry method and a wet method. The dry method is to obtain a zeolite by melting kaolin, squid and sodium carbonate and treating it with water, and the wet method is a method of mixing a sodium silicate solution and a sodium aluminate solution to form a zeolite. The main method is to dry, pulverize and sieve the gel to obtain zeolite. The structural formula of a general zeolite is Na ₂ Al ₂ Si ₃ O ₁₀ xH
It is represented by ₂ O.

[0012] Since zeolite retains its properties as an adsorbent, it has high hygroscopicity, which is not preferable from the viewpoint of stability against the environment, particularly humidity. Therefore, the zeolite obtained by any of the above production methods, calcium treatment, that is, ion exchange, while transferring from a strong alkali to a weak alkali, and by amorphization by firing,
The humidity dependency can be improved. Metals for performing ion exchange include Mg, Zn, Ba, Sr, and C in addition to calcium.
u, Sn, Fe, Ni, Cr and the like are effective in the present invention.

The structural formula is as follows. mMO ・ nNa ₂ O ・ pSiO ₂・ Al ₂ O ₃・ qH ₂
O (M is a metal composed of one or more divalent metals, and m, n, p, and q are arbitrary positive real numbers) The amount of the amorphous calcium-sodium-aluminosilicate spherical particles is as follows: 0.01 parts per 100 parts by weight of toner
The amount is preferably from 3 to 3 parts by weight, particularly preferably from 0.1 to 1 part by weight. If the above value is more than 3 parts by weight, the photoconductor may be damaged, which is not preferable.

The volume average particle size is 0.5 to 10 μm
Is preferably, and particularly preferably 1 to 5 μm. If the above value is less than 0.5 μm, the van der Waals force becomes large, and when added to the toner, it firmly adheres to the surface of the toner, lowering the fluidity of the toner. On the other hand, if the thickness is 10 μm or more, the surface area decreases, and the ability to impart a charge to the toner decreases, which is not preferable. Here, the volume average particle size is a value measured by the Coulter counter method.

As the binder resin used in the present invention, polystyrene, styrene-acryl copolymer, ethylene-vinyl acetate copolymer, vinyl acetate, acrylic and the like can be used. As the positive charge control agent, a nigrosine-based oil-soluble dye is the most common, but in addition,
Crystal violet, quaternary ammonium salts and the like can also be used in the present invention. As the magnetic powder, known powders such as various ferrites, magnetite, and hematite can be used. Further, if necessary, wax and the like can be added.

[0016]

The present invention will be described below in more detail with reference to examples. In addition, wt% in the text indicates weight%.

Example 1 Styrene resin Hymer UNI 3000 (manufactured by Sanyo Chemical Industries, Ltd.) 62 wt%, magnetic material MG-RF (manufactured by Mitsui Mining & Smelting Co., Ltd.)
35wt%, wax 550P (manufactured by Sanyo Chemical Industries) 1 w
t%, positive charge control agent TP-302 (made by Hodogaya Chemical Co., Ltd.) 2 w
was mixed using a Henschel mixer, melt-kneaded by a twin-screw extruder, pulverized by a jet mill pulverizer, and further classified to 9 μm by an airflow classifier to obtain a base toner. Amorphous calcium-sodium-aluminosilicate spherical particles JC-30 (Mizusawa Chemical Industries, Ltd.) having 0.5 parts by weight of dry colloidal silica R812 (manufactured by Nippon Aerosil Co., Ltd.) and a volume average particle diameter of 3 μm based on 100 parts by weight of the obtained base toner. (Manufactured by K.K.) and dry-mixed with a Henschel mixer to obtain a test toner. A commercially available copier (product name: NP-1215) employing a one-component developing method for the obtained toner
When an image was obtained using a Canon Inc.), an image density of 1.33 (using a Macbeth RD-918 reflection densitometer) was sufficiently obtained, and no fogging was observed. Further, when a printing test was performed on 20,000 sheets, an image density of 1.32 equivalent to the initial level was obtained even after printing 20,000 sheets, no fogging was observed, and a stable high-quality image was obtained. I was able to.

Example 2 Amorphous calcium-sodium-aluminosilicate spherical particles having a volume-average particle diameter of 3 μm and a dry colloidal silica R812 (manufactured by Nippon Aerosil Co., Ltd.) in an amount of 100 parts by weight of the base toner of Example 1 were used. (Manufactured by Mizusawa Chemical Industries)
One part by weight was added to obtain a test toner. A commercially available copier (trade name: NP-1) employing the obtained toner with a one-component developing method
215 Canon Inc.)
A sufficient image density of 1.30 was obtained, and no fogging was observed. In addition, when a 20,000-sheet printing test was performed,
Even after printing 20,000 sheets, the same image density as the initial 1.31
And no fogging was observed, and a high quality image could be stably obtained.

Comparative Example 1 Dry colloidal silica R812 (manufactured by Nippon Aerosil Co., Ltd.) only 0.3 part by weight was added to 100 parts by weight of the base toner of Example 1 to obtain a test toner. When an image was formed on the obtained toner using a commercially available copying machine (trade name: NP-1215 manufactured by Canon Inc.) employing a one-component developing method, an image density of 1.05 was obtained.
And fogging also occurred slightly. When a 20,000-sheet printing durability test was performed, after printing 20,000 sheets, the image density was 1.00, which was as low as the initial one, and the fog was worse than the initial one, resulting in an image that could not be used. .

Comparative Example 1 Dry colloidal silica R812 (manufactured by Nippon Aerosil Co., Ltd.) was added in an amount of 0.3 part by weight to 100 parts by weight of the base toner of Example 1, and tin oxide was used.
2 parts by weight of T-1 (manufactured by Mitsubishi Materials Corporation) were added to obtain a test toner. Using a commercially available copying machine (product name: NP-1215, manufactured by Canon Inc.) employing the one-component developing method, the obtained toner was used to produce an image.
Sufficient image density could not be obtained.

[0021]

Although the mechanism of action of the present invention is not entirely clear, the dry colloidal silica adheres to the toner surface and acts to improve the fluidity, and amorphous calcium-sodium-aluminosilicate spherical particles are used. It is considered that, by being present between toner particles, triboelectric charge is generated between the toner particles without impairing the fluidity, and acts as a role of imparting charge.
That is, the effects obtained by the present invention are as follows. Solving the drawbacks of using dry colloidal silica alone by using dry colloidal silica and amorphous calcium-sodium-aluminosilicate spherical particles in combination in a positively chargeable magnetic toner in the one-component development method. From the viewpoint of improving the fluidity and stabilizing the charge amount, a high quality image was stably obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-88554 (JP, A) JP-A-2-59768 (JP, A) JP-A-3-220563 (JP, A) JP-A-3- 257462 (JP, A) JP-A-4-70847 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08 CA (STN)

Claims (1)

(57) [Claims] 1. A one-component toner particle comprising a binder resin, a magnetic powder and a positive charge controlling agent as main components, and a volume average particle diameter of 0.5 to 0.5.
A positively chargeable magnetic one-component toner comprising 10 μm amorphous calcium sodium aluminosilicate spherical particles and dry colloidal silica.