JP2914051B2 - Negatively 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 negatively chargeable magnetic one-component toner that visualizes an electrostatic charge image on a photoreceptor 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 to the human body, and is currently being replaced with a photoreceptor using an organic material or a silicon-based photoreceptor. I have.

[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 negatively 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, the toner adheres firmly to the toner surface, and as a result, the fluidity of the toner tends to decrease. This decrease in toner fluidity inhibits the formation of a favorable sleeve layer pressure, leading 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 An object of the present invention is 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 negatively chargeable toner. It is an object. 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]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a toner comprising amorphous toner having a volume average particle diameter of 0.5 to 10 .mu.m, comprising a one-component toner particle having a binder resin, a magnetic powder and a negative charge controlling agent as main components.
The present invention relates to a negatively 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 is based on 100 parts by weight of toner.
It is preferably 0.01 to 3 parts by weight, particularly preferably 0.1 to 0.5 part by weight.
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,
It is not appropriate to add more than 3 parts by weight, since the fluidity does not increase in proportion to the amount added and the cost increases.

The amorphous calcium-sodium-aluminosilicate spherical particles are obtained by treating zeolite with calcium,
It is obtained by washing and baking. Zeolite is mainly produced by a dry method or 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 general structural formula of zeolite is Na ₂ Al ₂
It is represented by Si ₃ O ₁₀ xH 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 any positive real numbers)

The amount of the amorphous calcium sodium aluminosilicate spherical particles added is preferably 0.01 to 3 parts by weight, particularly preferably 0.1 to 1 part by weight, per 100 parts by weight of the toner. 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 more preferable, and particularly preferably 1 to 5 μm. If the above value is 0.5 μm or less, the van der Waals force becomes large, and when added to the toner, it firmly adheres to the toner surface, thereby lowering the toner fluidity. 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.

Next, the binder resin used in the present invention includes polystyrene, styrene-acryl copolymer,
Ethylene vinyl acetate copolymers, vinyl acetates, acrylics and the like can be used. As the negative charge control agent, a charge control agent such as a metal-containing azo dye-based or non-dye-based metal complex is known, but any other conventionally known charge control agents can be used. 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% shows weight%.

Example 1 Styrene resin Hymer UNI 3000 (manufactured by Sanyo Chemical Industries, Ltd.) 63 wt%, magnetic material MG-RF (manufactured by Mitsui Kinzoku Mining Co., Ltd.)
35wt%, wax 550P (manufactured by Sanyo Chemical Industries) 1
wt%, and 1 wt% of a negative charge control agent E-81 (manufactured by Orient Chemical Industries) were mixed using a Henschel mixer, melt-kneaded by a twin screw extruder, pulverized by a jet mill pulverizer, and further air-flowed. The particles were classified to 9 μm by a classifier to obtain a base toner. Amorphous calcium-sodium-aluminosilicate spherical particles JC-3 having a dry colloidal silica R812 (manufactured by Nippon Aerosil Co., Ltd.) 0.5 part by weight and a volume average particle diameter of 3 μm based on 100 parts by weight of the obtained base toner.
0 (manufactured by Mizusawa Chemical Industry Co., Ltd.) was added and dry mixed with a Henschel mixer to obtain a test toner.

An image was obtained from the obtained toner using a commercially available copying machine (trade name: NP-6150, manufactured by Canon Inc.) employing a one-component developing method, and the image density was 1.35 (Macbeth RD-reflection densitometer). 918), and no fog was observed. When a further 50,000-sheet printing test was performed, the image density was the same as the initial image density even after printing 50,000 sheets.
As a result, fogging was not observed, and a high-quality image was obtained stably.

Example 2 Dry colloidal silica R812 was used as the base toner of Example 1.
(Nippon Aerosil Co., Ltd.) 0.1 parts by weight, volume average particle size 3 μm
1 part by weight of amorphous calcium-sodium-aluminosilicate spherical particles JC-30 (manufactured by Mizusawa Chemical Industry Co., Ltd.) was added to obtain a test toner. When an image was formed on the obtained toner using a commercially available copying machine (product name: NP-6150, manufactured by Canon Inc.) employing a one-component developing method, the image density was 1.34.
And no fogging was observed. When a 50,000-sheet printing test was performed, an image density of 1.33 equivalent to the initial level was obtained after printing 50,000 sheets, and no fogging was observed. I got it.

Comparative Example 1 To the base toner of Example 1, only 0.2 part by weight of dry colloidal silica was added to obtain a test toner. A commercially available copier (product name: NP-615) employing the one-component developing method for the obtained toner
(Manufactured by Canon Inc.), the image density was as low as 1.10, and some fog occurred. When a 20,000-sheet printing test was performed, the image density was as low as 1.05 at the initial image density after printing 20,000 sheets, and the fog was worse than the initial image, and the image was unusable. .

Comparative Example 2 To the base toner of Example 1, 0.3 parts by weight of dry colloidal silica and 2 parts by weight of tin oxide T-1 (manufactured by Mitsubishi Materials Corporation) were added, and a test toner was obtained in the same manner. Using a commercially available copying machine (product name: NP-6150, manufactured by Canon Inc.) employing the one-component developing method, the obtained toner was used to produce an image. The image density was as low as 1.00, and sufficient image density was obtained. Could not.

[0022]

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. By using dry colloidal silica and amorphous calcium-sodium-aluminosilicate spherical particles in combination in the negatively chargeable magnetic toner in the one-component development method, the drawbacks of using dry colloidal silica alone are solved. 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 negative charge control agent as main components, and a volume average particle diameter of 0.5 to 0.5.
A negatively-chargeable magnetic one-component toner comprising 10 μm amorphous calcium-sodium-aluminosilicate spherical particles and dry colloidal silica.