JPS6255154B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polishing member used to polish the surface of an image holding member.

Electrostatic or toner images are formed by various electrophotographic processes. Image holding members on which electrostatic images or toner images are formed include electrophotographic photoreceptors and other image holding members.

Electrophotographic photoreceptors have various configurations in order to obtain predetermined characteristics or depending on the type of electrophotographic process to which they are applied. As typical electrophotographic photoreceptors, there are photoreceptors having a photoconductive layer formed on a support and photoreceptors having an insulating layer on the surface, which are widely used. The photoreceptor, consisting of a support and a photoconductive layer, is prepared by the most common electrophotographic processes: charging, image exposure and development.
Furthermore, it is used for image formation by transfer, if necessary. In addition, for photoreceptors equipped with an insulating layer, this insulating layer is used for purposes such as protecting the photoconductive layer, improving the mechanical strength of the photoreceptor, improving dark decay characteristics, or being applied to certain electrophotographic processes. It is established for the purpose of Typical examples of electrophotographic processes using such a photoreceptor having an insulating layer or a photoreceptor having an insulating layer include, for example, U.S. Pat. 15446 Publication, Special Publication No. 46-3713, Publication No. 23910-1972, Publication No. 24748-1974,
It is described in Japanese Patent Publication No. 42-19747, Japanese Patent Publication No. 4121-1974, etc.

A predetermined electrophotographic process is applied to the electrophotographic photoreceptor to form an electrostatic image, and this electrostatic image is developed and visualized.

Some representative image bearing members will be described next.

(1) For example, Japanese Patent Publication No. 32-7115, Japanese Patent Publication No. 32-7115,
As described in Japanese Patent Publication No. 8204 and Japanese Patent Publication No. 43-1559, an electrostatic image formed on an electrophotographic photoreceptor is transferred to another image holding member for the purpose of improving the repeatability of the electrophotographic photoreceptor. After transfer and development, the toner image is transferred to a recording medium. “Other image holding members” (2) used in this electrophotographic process also include
Other electrophotographic processes in which an electrostatic image is formed on another image holding member in correspondence with the electrostatic image formed on the electrophotographic photoreceptor include, for example, Japanese Patent Publication No. 45-30320 and Japanese Patent Publication No. 48-5063. As described in Japanese Patent Application Laid-Open No. 51-341, etc., an electrostatic image is formed on a screen-shaped electrophotographic photoreceptor having a large number of fine openings by a predetermined electrophotographic process,
By applying corona charging to another image holding member via this electrostatic image, the ion flow of the corona is modulated and an electrostatic image is formed on the other image holding member.
An example of this process is to develop this toner and transfer it to a recording medium to form a final image. "Other image holding members" (3) used in such electrophotographic processes Also, according to other electrophotographic processes, toner images formed on an electrophotographic photoreceptor or other image holding member are directly transferred to a recording medium. The toner image is not transferred to another image holding member, but is further transferred to another image holding member, and then the toner image is transferred from this image holding member to a recording medium and fixed. "Other image holding members" used in such electrophotographic processes. This process is particularly useful for forming color images or for high speed copying. Recording media are usually made of highly flexible materials such as paper or film, so it is better to transfer a three-color image onto a recording material while accurately aligning it, which causes almost no deformation. A more accurately aligned color image is formed by transferring a three-color image to an image-bearing member that can be formed from a material and then transferring it to a recording medium at once. Furthermore, it is effective for speeding up copying that the toner image is transferred to the recording medium via the image holding member. (4) Also, by applying electrical signals to the multi-needle electrode, an electrostatic image corresponding to the electrical signal is formed on the surface of the image holding member, and this can be developed into an image. An "image holding member" used in such an electrophotographic process. (1)～
Image holding members used in electrophotographic processes such as (4) do not require a photoconductive layer.

In this way, as image-holding members on which electrostatic images or toner images are formed, various materials with surface insulation are generally used, including electrophotographic photoreceptors.

The image holding member is required to have electrical properties according to the electrophotographic process to which it is applied, and durability of the image holding member is an important property. Durability is a property required when an image holding member is used repeatedly.

Generally, there are two causes for reducing the durability of an image holding member. One is residual toner,
The other one is charging treatment.

The toner image formed on the image holding member is transferred to a recording medium such as paper and fixed to form a final image.
The image holding member surface is then typically reused over and over again. At this time, a new toner image is formed on the surface of the image carrier every toner image forming cycle. For this reason, once a desired image forming cycle is completed, that is, after the toner image has been transferred, it is necessary to completely remove and clean the toner remaining on the surface of the image holding member.

Methods for removing toner include wiping or scraping the surface of the image holding member with a cleaning blade, rubbing and wiping with a web-like material, wiping with a fur brush, etc.

However, even if these methods are used to remove the toner remaining on the surface of the image carrier, the cleaning effect decreases as the number of repeated uses increases, and the cleaning process using the above methods gradually becomes less effective. Even if you do this, toner will remain on the surface. The reason for this is not clear, but since cleaning by the above method involves mechanical dynamic contact between the surface of the image carrier and the cleaning means, toner remaining on the surface of the image carrier may adhere or adhere during the cleaning process. It is thought that it causes welding and adheres to the surface of the photoreceptor.

If toner remains on the surface of such an image holding member,
A ghost image may appear in the toner image that is formed,
The image bearing member may become unusable due to the appearance of striations or damage to the surface of the image bearing member.

Further, when corona discharge is repeatedly performed as a charging process for forming an electrostatic image on an image holding member, the electrical characteristics of the surface of the image holding member are deteriorated due to corona ions. This is due to the energy generated when corona ions directly collide with the surface of the image holding member, or due to ionized substances such as oxygen, nitrogen, carbon dioxide, water, ammonia, and silicon generated by corona discharge. As the particles adhere, the molecules of the material that makes up the surface of the image holding member may be cut, oxidized, or deteriorated, or the ionized substances may adsorb moisture, resulting in a decrease in surface electrical resistance and the retention of static charges. It becomes impossible to use it as an image holding member.

Therefore, in order to reuse an image holding member to which residual toner has adhered or whose electrical characteristics have deteriorated, the surface must be polished to expose a new surface and restore the initial surface condition. I need to do it. In conventional methods for surface polishing, a powdered abrasive is applied directly to the surface of the image carrier for polishing, or the abrasive is dispersed in toner or impregnated into a web and supplied to the surface of the image carrier. Then, the polishing process was performed.

However, in the above-mentioned conventional method, if the abrasive remains on the surface of the image holding member, or if the abrasive is mixed into the toner, the quality of the toner image may deteriorate, or the abrasive may cause damage to the electrophotographic image. This has the disadvantage that it scatters inside the device and contaminates the parts inside the device. Furthermore, it has been extremely difficult to supply a constant amount of abrasive.

The main object of the present invention is to provide a polishing member effective for polishing the surface of an image holding member in order to solve the above-mentioned drawbacks.

The abrasive member of the present invention is characterized by having an abrasive agent dispersed in a water-soluble resin. In the abrasive member according to the present invention, since the abrasive agent is dispersed and contained in the resin, when the abrasive means is applied to the surface of the image holding member, the abrasive agent may remain on the surface of the image holding member, and the abrasive agent may remain on the surface of the image holding member. Since the abrasive is not mixed into the toner, the quality of the toner image is not degraded, and furthermore, the abrasive does not scatter into the electrophotographic device. Further, in order to polish the surface of an image holding member using the polishing member of the present invention, a resin surface containing a dispersed abrasive is brought into contact with the surface of the image holding member,
Since it is sufficient to move the image holding member and the polishing member relative to each other, the strength of polishing can be easily controlled by the strength of contact and the relative speed of movement. Thus, the abrasive member according to the present invention solves all the drawbacks pointed out in conventional polishing methods. The polishing action of a polishing member containing an abrasive dispersed in a resin is caused by the abrasive exposed on the resin surface rubbing against the surface of the image holding member. After the abrasive member has been used for a certain period of time, the abrasive particles that were initially exposed on the resin surface and contributed to the polishing are worn out and lose their polishing ability. However, since the linear structure resin is a resin that wears moderately, the resin also wears out as the abrasive particles exposed on the resin surface wear out. The contained abrasive particles now become newly exposed at the surface, and these newly exposed abrasive particles can replace the worn particles to perform the abrasive action, resulting in: The durability of the abrasive member of the present invention is very good. In particular, the water-soluble resin used to form the abrasive member according to the present invention is excellent in that it can easily achieve uniform dispersion of abrasives, which are generally considered to have a large specific gravity and are difficult to uniformly disperse. An abrasive member formed by applying the water-soluble resin containing the abrasive resin to a supporting member has good surface flatness and uniformity, and particularly excellent sustainability of the abrasive action. The reason why a water-soluble resin can form such a good abrasive member is thought to be due to the stabilization of the dispersion state of the abrasive by the action of the water-soluble resin as a surfactant.

In addition, even when the abrasive member is used for a long period of time, a portion of the water-soluble resin forming the abrasive member is hardly transferred to the surface of the image holding member, and the charging characteristics of the image holding member under high humidity are improved. , does not affect corona resistance properties, cleaning properties, etc. The water-soluble resins used in the present invention include polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, ethyl cellulose, alginic acid, starch, polyvinyl methyl ether, polyvinylethyl ether, etc., with hydroxyl groups, ether bonds, carboxyl groups or Polymers having carboxylates, polyvinylpyrrolidone, polyethylene oxide, casein, etc. Among these, polyvinyl alcohol or
A copolymer of polyvinyl alcohol is particularly good in terms of moisture resistance. In the case of a polyvinyl alcohol copolymer, one containing a vinyl alcohol component of 60 mol% or more, particularly 80 mol% or more is suitable.

A typical structure of the abrasive member according to the present invention is made by dispersing an abrasive in a water-soluble resin solution and applying and drying the abrasive on the surface of a supporting member such as a web, film, roller, or metal foil. Ru. Other methods for manufacturing the abrasive member include heating and melting a water-soluble resin to disperse the abrasive;
Monomers or low polymers that can be polymerized to synthesize a water-soluble resin, or aqueous solutions that contain an abrasive dispersed by dispersing an abrasive in these solutions, applying this to the surface of a supporting member, and polymerizing it. It is also possible to form a synthetic resin.

In another method, a water-soluble resin containing an abrasive dispersed therein may be attached to the supporting member using an adhesive or the like.

Typical specific examples of manufacturing abrasive members include:
Thoroughly mix and disperse the abrasive with a water-soluble resin binder,
For example, it is formed by coating and impregnating a web-shaped support member by a coating method such as spray coating.

As the abrasive, conventionally used abrasives are used. For example, calcium carbonate, cerium oxide, magnesium oxide, silicon oxide, magnesium silicate, calcium silicate, aluminum sulfate, calcium sulfate, barium sulfate, magnesium sulfate,
Boron nitride, etc. Among these, cerium oxide, silicon oxide, calcium carbonate, and barium sulfate are effective, and cerium oxide is particularly suitable.

The particle size of the abrasive is usually 0.01~20μ, especially 0.1
It is preferable to set it to ~10μ.

In addition, the ratio (weight ratio) of abrasive to resin is
In the range of 100:1 to 100:50, especially 100:5 to
A ratio of 100:15 is preferred.

When the image holding member is an electrophotographic photoreceptor, the most typical structure is a laminate of a photoconductive layer and a support. The support is formed from any material such as a metal plate such as stainless steel, copper, aluminum, or tin, paper, sheet, or resin film. The support may be omitted if necessary.

The photoconductive layer is S, Se, PbO, and S, Se, Te,
It is formed by vacuum deposition of an inorganic photoconductive material such as an alloy or intermetallic compound containing As, Sb, etc. In addition, when using the sputtering method, ZnO, CdS,
A photoconductive layer can also be formed by depositing a high melting point photoconductive substance such as CdSe or TiO ₂ on the support. Also,
When a photoconductive layer is formed by coating, organic photoconductive materials such as polyvinylcarbazole, anthracene, phthalocyanine, dye-sensitized or Lewis acid-sensitized materials, and mixtures of these with insulating binders can be used. . Also, ZnO,
Mixtures of inorganic photoconductors such as CdS, TiO ₂ , PbO, etc. with insulating binders are also suitable. Note that various resins are used for the insulation. The thickness of the photoconductive layer is
Although it depends on the type and characteristics of the photoconductive material used, it is generally preferred to have a thickness of about 5 to 100 microns, particularly about 10 to 50 microns. In addition, when an insulating layer is attached with the main purpose of protecting the image holding member, improving durability, dark decay characteristics, etc., the insulating layer is set to be relatively thin, and when the image holding member is used in a specific electrophotographic process, the insulating layer is set to be relatively thin. The insulating layer provided on the insulating layer is set to be relatively thick. Usually, the thickness of the insulating layer is set to 0.1 to 100μ, particularly 0.1 to 50μ.

As the resin used for forming the insulating layer, various ordinary resins can be used as appropriate. Examples include polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, acrylic resin, urethane resin, polycarbonate, silicone resin, fluororesin, epoxy resin, and the like.

The polishing process of the image holding member by the polishing member is usually performed after a toner image is formed on the image holding member, the toner image is transferred to a recording medium, and then the surface of the image holding member is cleaned by a cleaning means. is appropriate. Therefore, in this case, the abrasive member is arranged in the electrophotographic apparatus so that the cleaning process is followed by the polishing process.

The abrasive member may be in contact with the surface of the image holding member in the form of a flat plate or blade, or may be in contact with the surface of the image holding member in the form of a roll and rotated.

Example 1 As an abrasive, 100 parts (parts by weight, same hereinafter) of cerium oxide with a particle size of 4μ and a copolymer resin of vinyl alcohol (90 mol%) and vinyl acetate (10 mol%) (trade name: B-17, Disperse and dissolve 10 parts of Denki Kagaku Kogyo Co., Ltd. (friction coefficient hardness) in 100 parts of water, and thoroughly stir with a homogenizer at 10,000 rpm for 10 minutes.
Next, it was applied to the paper web using a bottom-feed reverse coater at a solid content of 10 g/m ² and heated at 100°C.
An abrasive member was obtained by passing it through a 10 m drying oven.

A photoreceptor was used which had a 35 μm thick photoconductive layer formed by dispersing 88 parts of cadmium sulfide in 12 parts of vinyl chloride-vinyl acetate copolymer resin on the surface of an Al cylinder, and a 30 μm thick insulating layer on the photoconductive layer. Note that the insulating layer of the photoreceptor is formed from a cured silicone resin (trade name: X-12-917, manufactured by Shin-Etsu Chemical).

This photoreceptor is charged with a primary charge +7KV corona charge, a secondary charge AC7.5KV corona charge, and is simultaneously irradiated with an image of 3.0lux.sec, and then exposed to full-surface exposure of 200lux.sec to form an electrostatic image. Dry development is performed to form a toner image, which is transferred to a transfer paper, and then the surface of the photoreceptor is cleaned with a fur brush, and the abrasive member is fed 0.1 mm per rotation of the photoreceptor to the surface of the photoreceptor. In this manner, the polishing process was performed by bringing the polishing member into contact. Even after repeating this electrophotographic process 250,000 times, no toner adhesion to the surface of the photoreceptor nor any decrease in surface electrical resistance was observed, and the copied images obtained after 250,000 copies were similar to the initial state. The image quality was maintained and it was clear.

In this example, if the polishing process using the polishing member was not performed, the electrophotographic process would be approximately
After 1000 repetitions, toner adhesion was observed on the photoreceptor surface. Fog also occurred in the toner image transferred to the transfer paper.

Example 2 An abrasive member was prepared in exactly the same manner as in Example 1 except that silicon oxide, calcium carbonate, or barium oxide was used instead of cerium oxide, and a similar experiment was conducted. Even after repeating the process 90,000 times, no toner fusion occurred on the surface of the photoreceptor, and a clear toner image was formed.

Example 3 The following experiment was conducted using the polishing member and photoreceptor of Example 1.

+7KV corona primary charging, AC7.5KV corona secondary charging and simultaneous exposure (3.1lux.sec) and 200lux.
An electrophotographic process was applied to the photoreceptor in an atmosphere of 85% relative humidity at 35° C., in which an electrostatic image was formed by exposing the entire surface to light at sec, and then polished with an abrasive member in the same manner as in Example 1. After repeating this electrophotographic process 5,000 times, the electrostatic image formed was dry-developed with toner and transferred to transfer paper, and the toner image formed on the transfer paper had a resolution of 8 lines/mm and was clear. It was an image.

In this example, when polishing with a polishing member was not performed, the toner image formed on the transfer paper was blurred, and the resolution could not be measured.

Example 4 In Example 1, the following linear resin (1) was used instead of the polyvinyl alcohol copolymer (trade name: B-17).
When a similar test was conducted using each of (3) to form an abrasive member using the same method, no abrasive was scattered or mixed into the toner even after 250,000 repetitions.
All the copied images obtained were of good quality and could be used effectively without toner sticking or decrease in surface electrical resistance of the photoreceptor.

(1) Polyvinyl alcohol resin (product name: K-
17, manufactured by Denki Kagaku Kogyo) (2) Carboxymethyl cellulose resin (product name:
Daicel CMC, manufactured by Daicel) (3) Ethyl cellulose resin (trade name: Metrol, manufactured by Shin-Etsu Chemical) Reference example In Example 1, the following (1) was used instead of polyvinyl alcohol copolymer resin (trade name: B-17). )~
(4) A test similar to Example 1 was conducted except that an abrasive member made of a non-linear curable resin was used. As a result, the abrasive action of the abrasive member disappeared after the electrophotographic process was repeated 5000 times, and toner fixation and image blurring occurred during subsequent electrophotographic process repetitions. The abrasive member in this reference example was formed by dispersing an abrasive (potassium oxide) and an uncured resin below in a solution, applying the solution, drying it, and curing it.

(1) Photocurable polyester resin (product name: UV-
102, manufactured by Kashiyu) (2) Photocurable epoxy resin (product name: W-4, manufactured by Dainichiseika) (3) Thermosetting silicone resin (product name: S-144,
(manufactured by Teijin Kasei) (4) Thermosetting acrylic resin (product name: Palslac, manufactured by China Paint)

Claims (1)

[Scope of Claims] 1. An abrasive member for an image holding member, characterized by having an abrasive agent dispersed in a water-soluble resin. 2. The polishing member for an image holding member according to claim 1, wherein the abrasive is cerium oxide. 3. The polishing member for an image holding member according to claim 1, wherein the water-soluble resin is polyvinyl alcohol or a polyvinyl alcohol copolymer.