JPH04124689A - Image forming method - Google Patents

Abstract

PURPOSE:To easily remove carrier remaining on a photosensitive body without damaging the surface of the photosensitive body by using both of a brush cleaning system and a blade cleaning system at the same time and using a conductive brush consisting of resin and a conductive material as a brush used for brush cleaning when cleaning is performed to remove the component of developer remaining on the photosensitive body. CONSTITUTION:At a cleaning stage, both of the brush cleaning system and the blade cleaning system are used at the same time. In the case, the brush cleaning is executed before the blade cleaning. It is necessary to execute the brush cleaning by the use of the brush consisting of the conductive resin material. The brush consists of a fibrous substance containing an antistatic agent, for example, the conductive material such as quaternary ammonium salt, carbon black and metallic oxide in binding resin used as the carrier, and it is desirable that the electric resistance thereof is within 10<2>-10<7>OMEGAcm<-1>.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an imaging method having an improved cleaning process.

(Prior Art) In electrophotography or electrostatic recording, an electrostatic latent image is formed on a photoconductor, and then toner is electrostatically attached to the electrostatic latent image to form a toner image. Subsequently, a copy image is formed by transferring the toner image onto a transfer material such as paper. On the other hand, toner remaining on the photoreceptor without being transferred is
It is removed using a cleaning device.

As the developer used in the above image forming method, a two-component developer consisting of a carrier and a toner is often used. When this developer is stirred in a developing device, frictional charging is generated between the carrier and the toner, and the toner is given a charge with a polarity opposite to that of the electrostatic latent image.

Conventionally, carriers with a larger particle size than l/toner (particle size 60 to 50 (ltIR)) have been used as the developer described above.However, when the particle size of the carrier is large, it is difficult to reproduce the gradation. In addition, toner particles tend to adhere to the background area.In recent years, in order to solve these drawbacks, carrier particle diameters have been made to be approximately the same as the toner particle diameters. For example, as a developer used in the magnetic brush development method, a magnetic powder-dispersed carrier with a small average particle size of 5 to 50, consisting of a binder resin and magnetic powder, and an average A developer mixed with toner having a particle size of 5 to 20 mm is known.

In addition, the cleaning method generally used in the cleaning process in image forming methods is blade cleaning. Blade cleaning has the advantage of being a low-cost and small-sized system, but it is not suitable for high speed and is insufficient for cleaning. Defects are likely to occur. On the other hand,
Although the fur brush cleaning method is known as a method that is suitable for high speed, it requires dust collection of the cleaned toner, which has the disadvantage of increasing both space and cost. Therefore, in recent years, a two-stage cleaning method that uses both brush cleaning and plate cleaning without a dust collector has been used, and it has been proposed to meet the demands for miniaturization and high speed suitability. There is.

(Problem to be Solved by the Invention) The above-mentioned two-stage cleaning method has a structure in which toner is electrostatically scraped off by plan cleaning in the first stage, and remaining toner is cleaned by blade cleaning in the second stage. However, the following problems occur. That is, today, the demand for low-potential, high-performance development is increasing, and in order to meet this demand and increase the mobility of the developer, a developer consisting of a magnetic powder-dispersed carrier and L-ner as described above has been developed. When used, since the magnetic powder dispersed carrier has a low specific gravity and low magnetic force, the catch tends to adhere to the surface of the photoreceptor. The carrier attached to the surface of the photoconductor has a chargeability opposite to that of the toner, so
When toner is electrostatically scraped off by brush cleaning, the toner sticks even more strongly onto the photoreceptor due to the repulsive polarity with the brush, causing a problem of damaging the surface of the photoreceptor during the next blade cleaning.

The present invention has been made in view of the above problems.

Therefore, an object of the present invention is to provide an image forming method that allows cleaning to be performed without depending on the environment and without damaging the surface of the photoreceptor.

(Means and effects for solving the problems) The image forming method of the present invention uses a two-component dry developer consisting of a toner and a dispersed carrier in which magnetic powder is dispersed in a binder resin.
The process includes a step of developing an electrostatic latent image formed on the photoreceptor, a step of transferring the formed toner image to a transfer material, a step of cleaning developer components remaining on the photoreceptor, and a step of cleaning the developer component remaining on the photoreceptor. The process of cleaning the components uses both brush cleaning and blade cleaning, and
The brush used in the brush cleaning is characterized by being a conductive brush made of resin and conductive material.

Next, the present invention will be explained in more detail.

In the image forming method of the present invention, an electrostatic latent image is formed on the photosensitive layer by a conventional method, or in order to develop the formed electrostatic latent image, magnetic powder is dispersed in a binder resin. A two-component dry developer consisting of a dispersed carrier and a toner is used.

In the present invention, the two-component dry developer consists of magnetic powder or acicular macnetite and granular magnetite in its dispersed carrier, and the ratio of acicular magnetite to granular magnetite is 0.2 to 1 by weight. It is preferable that it be within the range of . That is, when the content of acicular magnetite is a and the content of granular magnetite is β, it is preferable that α and β satisfy the relationship of 0.2≦α/β≦1. When α/β is lower than 0.2, the charge amount of the carrier is high and the saturation magnetization is low, so the carrier tends to adhere to the photoreceptor, and it also tends to charge the blank, which will be described later. As a result, the particles cannot be removed sufficiently in the cleaning process. On the other hand, α/β is 1
When the carrier is melted during manufacturing,
Problems arise in that an appropriate viscosity cannot be obtained, resulting in poor dispersion into the binder resin or in the carrier becoming brittle.

The two-component developer used in the present invention is composed of the following materials.

(1) As the carrier binder resin, polystyrene, polyacrylate,
Polymethacrylate, vinyl resin, polyester resin, polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile, polyether, polycarbonate, cellulose resin, polyamide, and copolymers of monomers constituting the polymer can be used.

The acicular magnetite used has an average particle size of 01 to 3ρ and a long axis/short axis ratio of 2 or more.

In addition, as granular magnetite, the average particle size is 0°1~3
IIn materials with hexahedral, spherical, and octahedral structures are used.

The blending ratio of these magnetites is preferably in the range of 50 to 80% by weight of the total amount or the weight of the carrier particles.

Carbon black, a surfactant, and a charge control agent can be added to the carrier in the present invention as conductivity modifiers, if necessary.

The average particle size of the carrier is 5 to 50 mm, preferably 20 to 50 mm.
It is set in the range of 40 prisoners. The average particle size is 5II! If it is less than 11, the magnetic force per carrier is small and the carrier tends to adhere to the photoreceptor. If it exceeds 50, the sharpness of the image will be lost and the image quality will deteriorate, and when the toner density is increased, toner background stains will tend to appear.

The carrier can be manufactured by kneading and pulverizing the above components, spray-drying a suspension obtained by dissolving the binder resin in a solvent and dispersing magnetite powder, or polymerizing the binder resin. In this case, any method may be employed, such as a method of dispersing magnetite powder in a monomer.

(2) Toner In the present invention, the toner is preferably configured so that when mixed with the carrier, the toner is triboelectrically charged to become positively charged. The binder resin used in the toner is limited depending on the fixing method, or the same binder resin as the binder resin used in the carrier can be used. Further, any pigment or dye can be used as the colorant, and is generally used in an amount of 25% by weight or less, preferably in the range of 1 to 20% by weight of the toner.

In addition, in order to impart positive chargeability to the toner, it is necessary to add a basic dye such as nigrosine dye, a charge control agent such as a quaternary ammonium salt, or use a binder resin containing nitrogen atoms. Bye.

The average particle size of the toner is preferably in the range of 5 to 20a+.

When the average particle size is lower than 5 mm, the fluidity of the toner deteriorates and the toner adheres to the background area, and when it exceeds 20 mm, the sharpness of the image is lost and the image quality deteriorates. Become.

The method for manufacturing the toner can be carried out in accordance with the method for manufacturing the carrier described above.

In the present invention, the toner image developed using the above developer is then transferred to a transfer material such as paper by a conventional method.

Developer components such as toner or carrier remaining on the photoreceptor are then cleaned in a cleaning step.

In the present invention, in the cleaning process, both the brush cleaning method and the blade cleaning method are used in combination, as described above. In that case, brush cleaning is performed before raid cleaning.

In the present invention, brush cleaning must be performed using a brush made of a conductive resin material. In this case, it is preferable that the brush and the carrier of the developer have a relationship such that the amount of charge between the plan and the carrier is -5 to +5 μC/g, and particularly, there is no charge. When the amount of charge between the brush and the carrier is -5 to +5 μC/g, the carrier remaining on the photoreceptor surface does not adhere to the brush or the photoreceptor surface electrostatically, but due to mechanical force. It floats up and is easily cleaned by subsequent blade cleaning.

In the present invention, the brush is preferably made of a conductive resin key material, and has an electrical resistance in the range of 102 to 10'Ωcan-'. Specifically, it is formed by using the binder resin used for the carrier and containing or coating it with a conductive material such as an antistatic agent, such as a quaternary ammonium salt, carbon black, or a metal oxide. Fibrous materials can be used, but are not limited thereto.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, in the following description, "part" means "part by weight."

Manufacture of developer A two toner Styrene-butyl acrylate 100 parts (80/20)
Copolymer carbon black (Regal 330, 10 parts manufactured by Cabot Corporation) Low molecular weight polypropylene 5 parts (Viscol 66 (IP, manufactured by Sanyo Chemical ■) Charge control agent (Bontron N-0: 1, manufactured by Orient Chemical ■) Above The ingredients were melt-kneaded using a Banbury mixer.

After cooling, the mixture was finely pulverized using a jet mill, and the finely pulverized product was further classified using a classifier to obtain toner particles having an average particle size of lia+.

With respect to 100 parts of this toner particle, the average particle size is 0. ] 1 part of female silica particle-free was dispersed and mixed using a Hennel mixer to prepare a toner having oxidized silica fine particles attached to the surface.

Preparation of carrier: Styrene-methyl methacrylate 100 parts (80 parts
/20) Copolymer acicular magnetite (long axis diameter 0.5 an, short axis diameter 0.0
5a+) 100 parts Granular magnetite (EPT-1000, 200 parts manufactured by Toda Kogyo ■) Polyvinylidene fluoride (KYNAR, 5 parts Penn W
aft) The above ingredients were melt-kneaded using a pressure kneader, and further crushed and classified using a turbo mill and a classifier to obtain an average particle size of 4.
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Next, the above toner and the above carrier were mixed at a weight ratio of 5:95 to prepare a two-component developer.

Developer B: When preparing the carrier in developer A, granular magnetite (EPT-1,
000, manufactured by Toda Kogyo ■), except that 300 copies were used.
A two-component developer was obtained in the same manner as developer A.

Example 1 An electrophotographic copying machine having an organic photoreceptor (FX
-5075, manufactured by Fuji Xerox) was used.

A brush prepared as follows was used for brush cleaning in the cleaning device. That is, 10% carbon black was added to an acrylic resin, melted and dispersed, and then stretched to produce a fibrous material, which was produced at a rate of 50,000 fibers/rT? A brush was prepared at a density of . (Electrical resistance lXIO3Ωcm −') Furthermore, a blade made of polyurethane was used as a blade for blade cleaning.

The cleaning device described above was attached to the electrophotographic copying machine, and a copying operation was performed using developer A. In that case, regarding the amount of charge between the carrier and the brush, the cleaning performance of the toner, and the presence or absence of image defects under low temperature and low humidity (10°C, 15% RH) and high temperature and high humidity (30°C, 85% RH). , conducted an evaluation. The results are shown in Table 1.

Comparative Example As a plan for Kobran cleaning, acrylic resin was melted and stretched to create a fibrous material, which was
00 wires/a (electrical resistance I
The copying operation was carried out under exactly the same conditions as in Example 1, except that a resistance of 1014 Ωcm −' or higher was used.

Comparative Example 2 A copying operation was performed under exactly the same conditions as in Example 1, except that a cleaning device that did not perform plan cleaning was used.

Example 2 A copying operation was carried out under exactly the same conditions as in Example 1, except that developer B was used instead of developer A.

Comparative Example 3 A copying operation was carried out under exactly the same conditions as in Comparative Example 1, except that developer B was used instead of developer A.

Example 3 As a brush for brush cleaning, 10% of quaternary ammonium salt was added to acrylic resin, melted and dispersed, and then stretched to create a fibrous material, which was
(electrical resistance IX1.
The copying operation was performed under exactly the same conditions as in Example 1, except that 07Ωam −' ) was used.

The results of Examples 2 to 4 and Comparative Examples 1 to 3 are also shown in Table 1.

The measurement conditions in Table 1 are as follows.

Amount of charge between the carrier and the brush: This is the value measured by cutting the brush fiber into a length of 1 cm, mixing and stirring with the carrier at a ratio of 3 cm, and using a blow-off measuring device.

Toner cleaning performance: An untransferred toner image of 5cIT1 width was formed on the photoreceptor and cleaned. (999 sheets mode x 3 consecutive tests) ○...No toner cleaning failure ×...Toner cleaning failure occurred Image quality defect: Under each environment, image quality and photoreceptor after copying 100,000 sheets The condition was visually evaluated.

(Effects of the Invention) As described above, in the present invention, the step of cleaning developer components remaining on the photoconductor uses both brush cleaning and blade cleaning, and the brush used for brush cleaning is made of resin and conductive material. Because it is a conductive brush made of a magnetic material, when a developer using a magnetic powder dispersed carrier is used for development, the carrier remaining on the photoreceptor will not damage the surface of the photoreceptor.
Moreover, it can be easily removed without depending on the environment.

Therefore, in a medium-high speed copying machine that is required to perform low-potential and high-speed development, a small and inexpensive cleaning system can be used to exhibit sufficient cleaning performance even in summer and winter environments.

Applicant: Fuji Xerox Co., Ltd.

Claims (3)

[Claims] (1) A process of developing an electrostatic latent image formed on a photoreceptor using a two-component dry developer consisting of a toner and a dispersed carrier in which magnetic powder is dispersed in a binder resin. In an image forming method that includes a step of transferring a toner image to a transfer material and a step of cleaning a developer component remaining on the photoreceptor, the step of cleaning the developer component includes a combination of brush cleaning and blade cleaning. However, the brush used in the brush cleaning is
An image forming method characterized by using a conductive brush made of resin and a conductive material. (2) The amount of charge between the brush and the dispersed carrier is -5 to +5
The image forming method according to claim 1, wherein the image forming method is μC/g or less. (3) The magnetic powder in the dispersed carrier of the two-component dry developer consists of acicular magnetite and granular magnetite, and the ratio of acicular magnetite to granular magnetite is in the range of 0.2 to 1 by weight. The image forming method according to claim 1, characterized in that: