JPH06118693A - Non-magnetic one-component developing method - Google Patents

Abstract

PURPOSE:To obtain a developing method by which a uniform toner thin layer is obtained on a developing roller and sufficient developing ability is obtained even in the case of non-magnetic toner having small particle diameter in a non-contact and non-magnetic one-component developing system. CONSTITUTION:In this non-contact and non-magnetic one-component developing method, non-magnetic one-component developer 3 is supplied to the developing roller 5, the thin layer of the developer 3 is formed on the surface of the roller 5 by a layer regulating member 4 and charge is given to the developer 3, and the developer 3 is allowed to fly because of a potential difference between a photosensitive drum 1 and the developing roller 5, an electrostatic latent image is developed in non-contact with the photosensitive drum 1 holding the electrostatic latent image, then the image is transferred on the transfer material. The developer in which tin oxide antimony is held in a free state in the non- magnetic toner mainly composed of binding agent resin and colorant is used as the developer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type non-magnetic one-component developing method for developing an electrostatic latent image using a non-magnetic toner.

[0002]

2. Description of the Related Art Generally, in electrophotography, an electric latent image is formed on a photoconductor, the latent image is developed with a toner, and the toner image is transferred to a transfer material such as paper, if necessary. It is fixed by a means such as heating or pressing to obtain a copy. As a developer used in such an electrophotographic method, a two-component developer including a toner and a carrier,
There is a one-component developer having the functions of toner and carrier at the same time. The one-component developer further includes a magnetic one-component developer,
Classified as non-magnetic one-component developer. The two-component developer has excellent electrophotographic characteristics such as transferability, fixability, and environmental resistance, but it requires a toner concentration sensor to control the mixing ratio of toner and carrier, and the life of the developer is short. However, there is a problem that the stirring mechanism of the developer becomes complicated. On the other hand, the magnetic one-component developer does not require the toner concentration sensor described above, and the developing device can be easily miniaturized. However, since it contains magnetic particles, it has a problem of poor fixability. From such a background, a method using a non-magnetic toner as a one-component developer has been proposed and put into practical use in recent years in order to achieve both compactness and simplification of the apparatus and fixing characteristics. The one-component developing method using a non-magnetic toner includes a contact type non-magnetic one-component developing method in which a developing roller carrying a developer is brought into contact with a photoreceptor having an electrostatic latent image to develop the developing roller and the photoreceptor. There is a non-contact type non-magnetic one-component developing method in which a non-magnetic toner on the developing roller is made to fly by developing with a constant gap between them. In the contact-type non-magnetic one-component developing method, the non-magnetic toner on the developing roller and the photoconductor having the electrostatic latent image come into contact with each other, so that the developability is good. Not only this, friction also occurs with the photoconductor drum, so the mechanical load on the non-magnetic toner is large. On the other hand, in the non-contact type non-magnetic one-component developing method, the developer is triboelectrically charged only by the layer regulating member, so that the mechanical load on the developer is small, but the non-contact type is not contacted. There is a problem that a sufficient image density cannot be obtained because the amount of the non-magnetic one-component developer (hereinafter, referred to as developability) that is generally flown from the developing roller to the photosensitive drum is smaller than that of the mold. .

In the non-contact type non-magnetic one-component developing method,
One of the means for improving the developability is to improve the fluidity by mixing and adhering hydrophobic silica or hydrophobic alumina as a fluidization improver on the surface of the non-magnetic toner which is a developer. It has been proposed to increase the amount of toner supplied to the latent image. However, such fluidization improvers generally have a strong positive or negative charge polarity. Therefore, when the non-magnetic toner is uniformly mixed and adhered to the surface of the non-magnetic toner, the non-magnetic toners repel each other electrostatically, which makes it difficult to obtain a uniform thin layer of the non-magnetic toner on the developing roller. Contrary to this, due to charging between the toner particles, toner particles having a charge opposite to the normal are generated,
There is also a problem that causes fogging in the non-image area. Further, in order to obtain a high-definition image, it is necessary to set the particle size of the non-magnetic toner to a small value such as a volume average particle size of 10 μm or less. Since the non-magnetic toner adheres strongly to the surface of the developing roller, the amount of the non-magnetic toner flying to the photoconductor drum is reduced, and the developability is further deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances. Therefore, an object of the present invention is to develop a non-contact non-magnetic one-component developing method in which a uniform thin toner layer can be obtained on a developing roller and sufficient developing property can be obtained even with a non-magnetic toner having a small particle size. To provide.

[0005]

The present inventors have solved the drawbacks of the non-contact type non-magnetic one-component developing method and obtained good developability even if the non-magnetic toner has a small particle size. As a result of diligent research on means for achieving the above, by using antimony tin oxide as a post-treatment agent for a non-magnetic toner, a uniform toner thin layer can be obtained on the developing roller, which is the above purpose,
It has been found that a non-magnetic one-component developer having good developability even with a small particle size can be provided, and the present invention has been completed. That is, according to the present invention, a non-magnetic one-component developer is supplied to a developing roller, a thin layer of the non-magnetic one-component developer is formed on the surface of the developing roller by a layer regulating member, and an electric charge is given to the developing roller and the developing drum. It is a non-contact type non-magnetic one-component developing method in which the non-magnetic one-component developing agent is caused to fly by a potential difference from a roller to develop in a non-contact manner on a photosensitive drum holding an electrostatic latent image, and then transferred to a transfer material. And a non-magnetic one-component developing method characterized in that the non-magnetic one-component developer is a non-magnetic toner mainly composed of a binder resin and a colorant, in which antimony tin oxide is held in a released state. Is.

The present invention will be described in detail below. Figure 1
FIG. 1 is a schematic configuration diagram of a developing device used in the non-contact type non-magnetic one-component developing method of the present invention. In the figure, 1 is a photosensitive drum,
Reference numeral 2 is a hopper, 3 is a non-magnetic one-component developer, 4 is a layer regulating member, 5 is a developing roller using an aluminum sleeve carrying the developer, 6 is a developer leakage preventing member, and 7 is a stirrer. In this developing device, an electrostatic latent image is formed on the photosensitive drum 1 by a known electrophotographic method. A non-magnetic one-component developer 3 is accommodated in the hopper 2, and the non-magnetic one-component developer 3 is carried by the layer regulating member 4 on the developing roller 5 so as to have a constant layer thickness, and the layer is formed. Electric charges are applied by friction with the restriction member 4. The developing roller 5 includes the photosensitive drum 1 and 120 μm
It is installed through a gap of 300 μm. A DC or AC voltage bias is applied to the roller. The non-magnetic one-component developer carried on the developing roller 5 is conveyed by the rotation of the developing roller 5, and is fly to the surface of the photosensitive drum 1 by the potential difference between the photosensitive drum 1 having an electrostatic latent image and the developing roller 5. Then, the electrostatic latent image is visualized without contact.

The non-magnetic toner constituting the non-magnetic one-component developer used in the above method of the present invention contains a binder resin and a colorant as main components. Examples of the binder resin include polystyrene, polyester, acrylic resin, styrene-acrylic copolymer, ethylene-
Examples thereof include, but are not limited to, vinyl chloride-based copolymers, ethylene-vinyl acetate-based copolymers, polyamides, polyethylenes, maleic acid resins, xylene resins, and phenol resins. As the colorant, for example, black colorants such as carbon black, acetylene black, lamp black, channel black, aniline black, and chromatic colors are farnal blue, permanent blue, nigrosine blue, phthalocyanine cyan pigments. , Rose bengal, xanthene magenta dye, quinacridone magenta pigment, monoazo red pigment, disazo yellow pigment, and the like, but are not limited thereto. These colorants are appropriately mixed in the range of 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. If desired, other components may be added to the non-magnetic toner.
For example, a charge control agent, an additive such as low molecular weight polypropylene and the like may be contained. The non-magnetic toner has a volume average particle size of 12 μm or less, preferably 3 to 9.5 μm. If it is less than 3 μm, sufficient fluidity cannot be obtained. On the other hand, if it is larger than 9.5 μm, the reproducibility of pixels such as thin lines and characters deteriorates.

The antimony tin oxide used in the present invention is a tin oxide fine powder doped with antimony, and is a metal compound in which a part of Sn in the atomic arrangement of SnO ₂ is substituted with Sb. Specifically, the product name T-1 of Mitsubishi Materials Corp. and the like can be mentioned. In the present invention, the antimony tin oxide retained in the non-magnetic toner in a free state preferably has a volume resistivity of 30 Ω · cm or more. If it is less than 30 Ω · cm, a good toner thin layer will not be formed on the developing roller, and the toner scattering from the developing machine will increase. The volume resistivity referred to in the present invention means that the antimony oxide 5 is present between the upper electrode having an area of 5 cm ^{2 and} the lower electrode having an area of 5 cm ² arranged in the cylinder.
It is obtained by weighing g, loading so as to apply a stress of 200 g / cm ² , applying a voltage, and measuring the resistance value between the electrodes with a tester. The amount of antimony tin oxide added to the non-magnetic toner is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the non-magnetic toner. If the amount is less than 0.1 parts by weight, the triboelectric charge amount of the non-magnetic toner is high and a practically sufficient image density cannot be obtained. On the other hand, when the amount is more than 5 parts by weight, the triboelectric charge amount is too low to form a good toner thin layer on the developing roller, and the toner scattering from the developing machine increases. In order to keep the antimony tin oxide in a free state in the non-magnetic toner, the non-magnetic toner is mixed at a predetermined mixing ratio using a mixer such as a normal powder mixer, such as a Henschel mixer or a super mixer. It can be carried out by stirring a mixture of the above and antimony tin oxide. When a powder mixer such as a Henschel mixer or a super mixer is used, mixing can be performed for a relatively short time under mild stirring conditions. Further, in order to adjust the fluidity, a hydrophobicity improver such as hydrophobic silica or hydrophobic alumina may be added at the same time as the antimony tin oxide. Also in this case, it is possible to use the same powder mixing method as described above.

[0009]

In order to obtain a uniform thin toner layer on the developing roller, it is necessary to prevent electrostatic repulsion between toner particles and electrostatic aggregation between toner particles due to charging between toner particles. Is. By holding the antimony tin oxide in a free state on the surface of the non-magnetic toner, the electrostatic repulsion and aggregation of the toner particles as described above can be reduced, and a good toner thin layer can be formed on the sleeve. . When the toner particle size is small, the triboelectric charge amount on the developing roller is generally high and the developability is poor.
Against such a phenomenon, addition of antimony tin oxide makes it possible to reduce the triboelectric charge amount, which is an effective means for obtaining good developability.

[0010]

EXAMPLES The present invention will be described below based on examples. In the examples, “part” means “part by weight”. Example 1 The raw materials were mixed, melt-kneaded, and pulverized and classified according to the following formulation,
A non-magnetic toner having a volume average particle diameter of 7.5 μm was obtained. To 100 parts of this non-magnetic toner, antimony tin oxide (trade name, manufactured by Mitsubishi Materials; T-1 volume resistivity; 93Ω)
(Cm) was added and stirred with a Henschel mixer for 2 minutes to obtain a non-magnetic one-component developer of the present invention.

Example 2 To 100 parts of the non-magnetic toner of Example 1 was added 0.45 part of antimony tin oxide (trade name, manufactured by Mitsubishi Materials; T-1 volume specific resistance; 93 Ω · cm) and hydrophobic alumina (Japan). 0.25 parts of trade name; RFY-C) manufactured by Aerosil Co., Ltd. was added at the same time, and a non-magnetic one-component developer of the present invention was obtained by the same mixing method as in Example 1.

Comparative Example 1 The non-magnetic toner of Example 1 itself was used as a non-magnetic one-component developer for comparison.

Comparative Example 2 To 100 parts of the non-magnetic toner of Example 1, 0.25 part of hydrophobic alumina (trade name: RFY-C manufactured by Nippon Aerosil Co., Ltd.) was added, and the same mixing method as in Example 1 was used. A non-magnetic one-component developer for comparison was obtained.

Using the non-magnetic one-component developer obtained by the above operation, a commercially available magnetic one-component printer (manufactured by Kyocera Corp.)
A print test was conducted using a modified machine (trade name: L-880) (developing bias was modified to a DC voltage of -100V and the surface potential of the photoconductor was modified to -900V). As a result, in each of the non-magnetic one-component developers of Examples 1 and 2, a uniform thin toner layer was obtained on the developing roller, and the non-magnetic one-component developer transferred from the photosensitive drum to the transfer paper was obtained. When the solid image was measured with a Macbeth reflection densitometer, good image densities of 1.35 in Example 1 and 1.36 in Example 2 were obtained, and a sufficient amount of the non-magnetic one-component developer from the developing roller to the photosensitive drum was obtained. It has been confirmed that is flying.
On the other hand, the non-magnetic one-component developers of Comparative Examples 1 and 2 could not obtain a uniform thin toner layer on the developing roller, had a high triboelectric charge amount, and measured solid images with a Macbeth reflection densitometer. Then, Comparative Example 1 is 0.65, and Comparative Example 2 is 0.
It was confirmed that the image density was as low as 72, and the flying amount of the non-magnetic one-component developer onto the photosensitive drum was small.

[0015]

As described above, according to the present invention, a uniform thin toner layer can be obtained on the developing roller by holding tin oxide antimony in a state where it is released on the surface of the non-magnetic toner, and the non-magnetic toner is obtained. Even if the toner has a small particle size, good developability can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a non-contact type non-magnetic one-component developing device for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Hopper 3 Non-magnetic one-component developer 4 Layer regulating member 5 Developing roller 6 Developer leakage prevention member 7 Stirrer

Claims (4)

[Claims] 1. A non-magnetic one-component developer is supplied to a developing roller, a thin layer of the non-magnetic one-component developer is formed on the surface of the developing roller by a layer regulating member, and an electric charge is applied to the developing roller and the photosensitive drum and the developing roller. A non-contact type non-magnetic one-component developing method in which the non-magnetic one-component developer is caused to fly by a potential difference between A non-magnetic one-component developing method characterized in that the non-magnetic one-component developer is a non-magnetic toner mainly composed of a binder resin and a colorant, in which antimony tin oxide is held in a released state. 2. The nonmagnetic one-component developing method according to claim 1, wherein 0.1 to 5 parts by weight of antimony tin oxide is added to 100 parts by weight of the nonmagnetic toner. 3. The non-magnetic one-component developing method according to claim 1, wherein the volume resistivity of antimony tin oxide is 30 Ω · cm or more. 4. The volume average particle diameter of the non-magnetic toner is 3 to.
The nonmagnetic one-component developing method according to claim 1, wherein the nonmagnetic one-component developing method is 9.5 μm.