JPH05224451A - Coating particle for surface of photosensitive body and picture image forming method - Google Patents

Abstract

PURPOSE:To provide coating particles for the surface of a photosensitive body or a cleaning member with which the toner remaining on the photosensitive body can be removed without damaging the surface of the photosensitive body and without causing filming of surfaces of the photosensitive body or an electrifying member in the cleaning process of electrophotographic system or the like. CONSTITUTION:The coating particles are almost spherical silica fine particles, and especially, spherical silica fine particles produced by deflagration method are preferable. These silica fine particles are used for the formation of picture images by electrophotographic method or the like. A powder containing the silica fine particles is supplied to the surface of a photosensitive body in the area not to be developed in such processes to develop electrostatic latent images on a carrier body for latent images, to transfer the formed toner images to a transferring member, and to remove the developmer component remaining on the electrostatic latent image carrier body. In the process to remove the developer component, the powder containing the silica fine particles is preferably deposited on at least one member of brush or blade.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to particles for coating an electrophotographic photoreceptor surface and / or a cleaning member.

[0002]

2. Description of the Related Art In electrophotography, an electrostatic latent image formed on a photoconductor or the like is developed with a developer, toner on the photoconductor is transferred to a transfer material such as paper or sheet, and then heat, The toner is fixed by using a solvent, pressure or the like to obtain a permanent image, and at that time, the toner remaining on the photoreceptor is cleaned. Therefore, when copying, a system with stable repeated characteristics is completed only when each process is fully functional. In particular, in the cleaning step among the above steps, since the photoconductor and the cleaning member are in direct contact,
There is a possibility of causing damage to the photoreceptor such as scratches and abrasion on the surface thereof, and on the other hand, there is a concern that image quality defects may occur due to poor cleaning, so high cleaning performance is required. In order to meet these requirements, external addition of inorganic fine powders such as silica, fatty acids, their metal salts and their derivatives, and various auxiliaries such as polyolefins to toners has been proposed to improve fluidity, durability, or cleaning properties. Improvements are being made.

[0003]

However, in the conventionally proposed additives, although inorganic compounds such as silica, titania and alumina significantly improve the fluidity, the surface layer of the photoconductor is dented by the fine powder of the hard inorganic compound. There is a problem in that the toner is apt to be scratched, and the toner is apt to adhere to the scratched portion. Further, in recent years, the use of recycled paper is increasing for the purpose of resource saving, but in general, recycled paper has a problem that a large amount of paper dust is generated. Induces poor cleaning.

In order to solve these problems, external additives such as fatty acid metal salts (JP-A-60-198556) and polyolefins (JP-A-61-231562 and 61-231563) are added as additives. Is being considered. In all of the materials disclosed in the above publications, the particle size of the additive is as large as 3 to 20 μm, and a considerable amount of addition is required to efficiently bring out the effect. In addition, although it is initially effective, the film formation as a lubricant is not uniform due to the filming unique to the additive (lubricant), which causes problems such as white spots and image blurring in the image. On the other hand, coating of a photoreceptor with a fine powder of a homopolymer or a copolymer of an acrylic acid ester monomer, a methacrylic acid ester monomer, a styrene-based monomer and the like (Japanese Patent Publication No. 2-3188) has been studied. However, recently, the copying speed tends to be higher, and along with that, the stress (load, speed) applied to the photoconductor during cleaning also increases.
Therefore, the resin-based fine powder as described above is deformed by the stress during cleaning and causes a problem such as filming. Further, there is a drawback that the polarity of the photoconductor used is limited due to the charging polarity of the resin itself.

Therefore, the present invention has been made in view of the above-mentioned actual situation of the prior art. That is, the object of the present invention is not to damage the photoreceptor surface in the cleaning step,
Another object of the present invention is to provide particles for coating a photoreceptor surface and / or a cleaning member, which can remove residual toner without causing a filming phenomenon or the like on the photoreceptor surface or the charging member surface.

[0006]

As a result of intensive studies, the present inventors have found that the above object can be achieved by coating the surface of a photoreceptor and / or a cleaning member with substantially spherical silica fine particles. Has been completed.

That is, the present invention resides in particles for coating the surface of a photosensitive member, which contain silica particles having a substantially spherical shape. The present invention also includes a step of developing the electrostatic latent image on the electrostatic latent image carrier, a step of transferring the formed toner image to a transfer member, and a developer component remaining on the electrostatic latent image carrier. In the image forming method having a step of removing, a powder containing substantially spherical silica fine particles in a region other than the developing region is supplied to the surface of the photoconductor. In the image forming method, the step of removing the developer component preferably uses a brush and / or a blade to attach powder containing substantially spherical silica fine particles to at least one member thereof.

The present invention will be described in detail below. As the particles for coating the surface of the photoreceptor and / or the cleaning member according to the present invention, substantially spherical silica fine particles having a bulk density of 300 g / l or more (hereinafter, simply referred to as spherical silica fine particles) can be used. Silica fine particles having a bulk density of 300 g / l or more can be obtained by the deflagration method. Silica fine particles produced by the deflagration method are produced by a rapid combustion reaction of silicon and oxygen at a reaction rate of about several hundred meters per second or less. In general, the fine silica particles have a smooth spherical surface and a density of 2.1 mg / m 2.
m ³ or more. I) Shape observation from SEM photograph In the present invention, the ratio of the minor axis / major axis of the circle of the projected image is 0.
Those having a ratio of 8 or more are preferable, and those having a ratio of 0.9 or more are particularly preferably used. However, when the ratio of the minor axis / major axis of the circle of the projected image was determined, both were 0.90 or more, It had a spherical shape. II) Wadell's true sphericity

[Equation 1] (1): Calculated from the average particle size. (2): A BET specific surface area was used as a substitute using a Shimadzu powder specific surface area measuring device SS-100 type. In the present invention, the sphericity Ψ of 0.6 or more can be used, and the sphericity Ψ of the spherical silica fine particles used is particularly preferably 0.8 or more. It was confirmed that all were 0.80 or more.

Due to the characteristics that the above spherical silica fine particles are hard and difficult to deform, the silica fine particles themselves cause filming on the photoconductor even during cleaning under high stress (high load, high speed, etc.). Since it is spherical, it plays a role of a roller and functions as an interaction reducing agent between the cleaning blade and the photoconductor. Also,
Since it has little impact on charging, it can be used for both positive and negative polarity photoconductors. The average primary particle size (hereinafter referred to as average particle size) of the spherical silica fine particles is usually 0.05 to 3.0 μm, and preferably 0.1 to 1.0 μm. When it is less than 0.05 μm, the spherical silica fine particles are buried in the concave and convex portions of the toner surface, and the role of the roller, that is, the role as an interaction reducing agent is reduced. On the other hand, if it is larger than 3.0 μm, when the spherical silica fine particles are located between the blade and the surface of the photosensitive member, there is a drawback that toner particles to be cleaned pass through, that is, cleaning failure occurs.

In order to coat the surface of the photoconductor with the spherical silica fine particles of the present invention, it may be supplied from the outside. For example, the fine particles are put into a small sack made of a sack cloth, and the cleaning member or the photoconductor is manually dusted. Sting may be performed, or a web to which fine particles are attached, a sponge roll, or the like may be installed in front of the cleaning member so that the fine particle coating can be stably formed on the photoreceptor during cleaning. Further, when the cleaning step uses one or both of brush cleaning and blade cleaning, by attaching the particles to either or both of the brush and the blade, a fine particle coating is stably formed on the photoreceptor. You can do it like this.

In the electrophotographic method using such fine particles, the target toner is a two-component toner containing a binder resin and a colorant as essential components, a magnetic one-component toner containing a magnetic material, or a capsule toner. The average particle size is not more than 30 μm, especially 3 to 20 without any limitation.
It is preferable to set in the range of μm. Further, when the toner is used as a two-component developer, the carrier used is not particularly limited as long as it is a known one, and it is an iron powder carrier, a ferrite carrier, a surface-coated ferrite carrier, a magnetic powder. A dispersion type carrier or the like can be used. As the electrostatic latent image carrier, a conventionally known one such as a selenium-based photoconductor, an organic photoconductor, an amorphous silicon photoconductor, or those whose surface is optionally overcoated is used. It is possible. As the developing machine, any conventionally known two-component developing machine or one-component developing machine can be used. As a cleaning means for removing the toner remaining on the photoreceptor, a cleaning method by blade pressure bonding, a fur brush cleaning method, or any other known method can be used.

The particles for coating the surface of the photoreceptor of the present invention can be appropriately used depending on the dry process, but in general, they are generally used for electrostatic photography on an electrostatic latent image carrier such as electrophotography and electrostatic recording. After the latent image is formed, the electrostatic latent image is visualized by the developer in the developing machine, the visible image is transferred to another carrier, and then the toner remaining on the electrostatic latent image carrier is cleaned. Can be used.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following description, all "parts" mean "parts by weight". The bulk densities of the spherical silica fine particles and colloidal silica used in Example 1 and Comparative Example 4 were measured by the following method. 100
Silica fine particles were gradually added to 100 ml using a ml measuring cylinder. At that time, no vibration was applied.
The bulk density was measured by the weight difference before and after the silica in the graduated cylinder was placed. Bulk density (g / l) = silica amount (g / 100 ml) × 10 Example 1 Binder resin [styrene-butyl acrylate copolymer (80/20)] 100 parts Carbon black (R330: manufactured by Cabot Corporation) ) 10 parts Low molecular weight polypropylene (Viscor 660P: manufactured by Sanyo Kasei Co., Ltd.) 5 parts Charge control agent (P-51: manufactured by Orient Chemical Industry Co., Ltd.) 2 parts The above components are melt-kneaded by a Banbury mixer, and after cooling, finely ground by a jet mill. Then, the particles were classified by a classifier to obtain toner particles having an average particle size of 11 μm. To 100 parts of this toner, 2 parts of titanium dioxide fine particles having an average particle size of 0.05 μm was added, and dispersed and mixed by a Henschel mixer to prepare a toner.

Next, styrene-butyl methacrylate copolymer (70/30) 100 parts Magnetite (EPT-1000: manufactured by Toda Kogyo Co., Ltd.) 200 parts Polyvinylidene fluoride (KYNAR: manufactured by Penn Walt) 5 parts under pressure The mixture was melted and kneaded with a kneader, further pulverized and classified using a turbo mill and a classifier to obtain a carrier having an average particle size of 50 μm. A two-component developer composition was prepared by mixing 5 parts of the above toner and 95 parts of this carrier. And
Voucher (crude cloth) in which spherical surface silica fine particles having an average particle size of 0.7 μm (bulk density of about 575 g / l) (KMP-105: manufactured by Shin-Etsu Chemical Co., Ltd.) are included on the surface of the photoreceptor of the modified Vivace 800 (manufactured by Fuji Xerox) The fine particles were adhered by performing dusting using a small bag, and a copying test was performed using the above developer.

Example 2 A copying test was conducted in the same manner as in Example 1 except that spherical silica fine particles were adhered to the cleaning brush instead of the surface of the photoreceptor of the modified Vise 800 (manufactured by Fuji Xerox Co., Ltd.).

Example 3 A copy test was conducted in the same manner as in Example 1 except that spherical silica fine particles were adhered to the cleaning blade instead of the photoreceptor surface of the modified Vise 800 (manufactured by Fuji Xerox Co., Ltd.).

Example 4 Except that spherical silica fine particles were attached to a cleaning brush and a cleaning blade instead of the surface of the photoreceptor of the modified Vise 800 (manufactured by Fuji Xerox Co., Ltd.).
A copy test was conducted in the same manner as in Example 1.

Example 5 Spherical silica fine particles were adhered to the photoreceptor of a modified Vise 800 (manufactured by Fuji Xerox Co., Ltd.) by dusting with a pouch containing spherical silica fine particles, and the cleaning brush and the cleaning blade were further cleaned. A copying test was conducted in the same manner as in Example 1 except that spherical silica fine particles were also attached.

Comparative Example 1 A copying test was conducted in the same manner as in Example 1 except that spherical silica fine particles were not adhered to the surface of the photoreceptor of the modified Viverse 800 (manufactured by Fuji Xerox Co., Ltd.).

Comparative Example 2 Example 4 was repeated except that methyl methacrylate-styrene copolymer (50/50) fine particles having an average particle size of 0.5 μm were adhered to the cleaning brush and the cleaning blade.
A copy test was conducted in the same manner as in.

Comparative Example 3 Polyvinylidene fluoride fine particles (KYN) having an average particle size of 0.3 μm were used for the cleaning brush and the cleaning blade.
AR: Penn Walt) was attached.
A copy test was conducted in the same manner as in Example 4.

Comparative Example 4 A copying test was conducted in the same manner as in Example 4 except that the colloidal silica fine particles (R972: manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 16 nm obtained by the hydrolysis method were attached to the cleaning brush and the cleaning blade. It was In addition,
The bulk density of colloidal silica obtained by the usual hydrolysis method is 5
It is in the range of 0 to 200 g / l, and in this comparative example, a bulk density of about 50 g / l was used.

The results obtained from the copy test of Korira are shown in Table 1. The test methods and evaluation criteria are as follows. 1) Cleaning Performance A black belt having a width of 5 cm was subjected to blade cleaning in a 999-sheet mode × 3 times in a non-transferred state. This evaluation is a stress test, and G1 to G3 cause no problem during normal copying, and G4 to G5 cause poor cleaning during normal copying. G1: The toner on the surface of the photoconductor could be cleaned without any problem. G2: At 2500 sheets or more, some poor cleaning occurred. G3: Poor cleaning occurred in 1500 to 2499 sheets. G4: Poor cleaning occurred at 500 to 1499 sheets. G5: Poor cleaning occurred at 499 sheets or less. 2) Abrasion amount of photosensitive material After taking 100,000 copies, the abrasion amount of the photoconductor was measured. 3) Image Quality Defects 100,000 copies were taken, and the image quality of the copies and defects on the surface of the photoconductor were observed. No problem: No image defects such as black spots, black streaks, and fog and scratches on the surface of the photoconductor were observed between 100,000 copies and after 100,000 copies. * 1: Black streaks due to poor cleaning and black spots due to photoconductor scratches occurred from about 800 copies. * 2: Black streaks occurred due to filming after about 1000 copies. * 3: Black streaks due to poor cleaning and black spots due to photoconductor scratches occurred from about 200 copies.

[0024]

[Table 1]

[0025]

INDUSTRIAL APPLICABILITY The particles for coating the surface of the photoreceptor and / or the cleaning member of the present invention are spherical silica fine particles, and particularly spherical silica fine particles (average particle diameter: 0.5 to 3.0 μm) produced by the deflagration method. By adhering it to the surface of the photoconductor and / or the cleaning member, it has a spherical shape and is hard to be deformed, so that it does not damage the surface of the photoconductor in the cleaning step and does not damage the surface of the photoconductor or the surface of the charging member. Does not cause a filming phenomenon and functions as an interaction reducing agent when removing the residual toner.

Front page continued (72) Inventor Takayoshi Aoki 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Takematsu Office

Claims (3)

[Claims] 1. Particles for coating the surface of a photoreceptor, which contain substantially spherical silica fine particles obtained by the deflagration method. 2. A step of developing the electrostatic latent image on the electrostatic latent image holding member, a step of transferring the formed toner image to a transfer member, and removing a developer component remaining on the electrostatic latent image holding member. In the image forming method including the step of, the powder containing substantially spherical silica fine particles by the deflagration method is supplied to the surface of the photoconductor outside the developing area. 3. The step of removing the developer component uses a brush and / or a blade, and at least one member of the brush and / or the blade is made to adhere a powder containing substantially spherical silica fine particles by deflagration method. The image forming method according to claim 2, wherein: