JP3122743B2 - Transfer roller and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art In a copying machine or the like utilizing an electrophotographic system, a method of transferring a toner image formed on a photosensitive drum or the like to paper or the like includes a corona transfer method using a corona charger, and a transfer method having an elastic layer. A transfer roller system in which paper to be transferred by a roller is mechanically pressed against a toner image carrier, or a bias voltage is applied and pressed, has been put to practical use. The transfer roller used in the transfer roller system generally includes a metal core, an elastic layer wound around the core, and a surface coating layer that covers the surface of the elastic layer if necessary. Recently, the technology of the transfer roller system has been improved.
JP-A-154086, JP-A-3-202885, JP-A-4-16397, and JP-A-4-2
Various proposals have been made in Japanese Patent Publication No. 08973.

[0002]

By the way, in the transfer roller system, a small amount of contaminants, for example, siloxane or a plasticizer, ooze out from the polymer foam or the like constituting the transfer roller, and contaminate the surface of the photosensitive drum. However, there is a problem of deterioration, and a problem that toner adheres to the transfer roller and soils the paper. The present invention has been completed by studying these problems of the transfer roller system, that is, a transfer roller that does not contaminate the photosensitive drum and adheres no toner.

[0003]

According to the present invention, there is provided a transfer roller for use in an electrophotographic apparatus constituted by winding a foamed elastic body around a cored bar. Larger than the diameter and the roller surface is
It is partially coated in a fine patch by fluororesin or silicone resin, that is, many resins adhere to the peaks of the surface roughness, and do not adhere to the valleys,
Provided is a transfer roller characterized in that the amount is small even if it adheres. An elastic body containing a foaming agent wrapped around a core is foamed in a mold so that the average bubble diameter does not fall below the average diameter of the toner to be used. By removing the skin layer formed on the surface, the surface roughness is formed to a size not less than the average particle size of the toner used, and the roller surface is partially covered with fluororesin or silicone resin in fine patches. A method of manufacturing a transfer roller, characterized in that a large amount of resin is adhered to the peaks of the surface roughness, and a small amount of the resin is not adhered to the valleys even if it is adhered. I will provide a. Spray coating is suitable for coating a fluororesin or a silicone resin.

[0004]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventor has found, in a study for solving the above-mentioned problem, a surprising fact completely different from those conventionally considered. That is, conventionally, for example, Japanese Patent Application Laid-Open Nos.
For the purpose of preventing the toner from adhering to the transfer roller and contaminating the photosensitive drum and making it difficult to clean the toner, as in the transfer roller described in JP-A-88585 and JP-A-4-208973, The surface roughness is finer than the toner. In addition, a uniform resin coating layer is provided on the surface as necessary in order to adjust the conductivity and facilitate the separation of the paper. However,
As a result of research, they have found that it is not always better to make the surface roughness of the transfer roller smaller or to coat the resin layer on the surface uniformly. Based on this fact, the transfer roller of the present invention improves the microscopic surface shape and configuration of a known transfer roller used in an electrophotographic apparatus, which is configured by winding a foamed elastic body around a cored bar. By doing so, a very small amount of contaminants ooze out of the transfer roller, thereby contaminating and deteriorating the photosensitive drum and preventing toner from adhering.

The transfer roller and the method of manufacturing the transfer roller of the present invention will be described in detail. First, a filler for adjusting conductivity and hardness, for example, carbon black or metal oxide, and a necessary blowing agent, vulcanizing agent, etc. are added to an unfoamed elastomer, for example, silicone rubber or urethane rubber. The kneaded foamed elastic material is extruded, for example, by an extruder and wound around a cored bar fed to the extruder and a crosshead. A metal core wound with a foamed elastic material is set in a mold, heated, foamed, and fixed to the metal core. In the present invention, in addition to the hardness and conductivity of the obtained foamed elastic body, the amount of the foaming agent and the foaming conditions can be adjusted so that the average bubble diameter does not become smaller than the average particle diameter of the toner used. is important. The foamed roller is removed from the mold, and the non-foamed or low-foamed skin layer formed on the surface is usually removed to expose the foamed layer. If the surface roughness of the foamed roller is larger than the average particle diameter of the toner used, depending on the manufacturing method and conditions, it may not be necessary to delete the surface.

In this way, a roller having a surface roughness larger than the average particle size of the toner to be used is manufactured. The surface of this roller is further coated with a fluororesin or silicone resin (hereinafter abbreviated as “fluorine resin or the like”),
Partially applied to fine patches. In this fluororesin, etc.,
A conductive substance such as carbon is often added in order to impart conductivity. In the present invention, it is not preferable that the roller surface is uniformly covered with a fluororesin or the like. It is necessary that fluororesin or the like is partially adhered to the roller surface in a fine patch. The fine range here is on the order of sub-microns to hundreds of microns.
The mottled shape may be any of a mottled shape, a sea-island shape, a mesh shape, a blind shape, etc., and it does not matter whether it is regular or irregular. Partially coated means that the coated part and the uncoated part are not separated from each other in a large area, but they are finely intermingled and distributed. It means being in a state. A preferred embodiment of the coating is that a large amount of the resin adheres to the peaks on the roller surface and does not adhere to the valleys, or even a small amount of the resin adheres to the valleys.

[0007] Coating is carried out by a method of transferring a resin containing a fibrous conductive material in an appropriate solvent and transferring the resin with a roll coater, a method using a gravure coater, a screen coater, a reverse roll coater, or the like;
Alternatively, it can be carried out by using a spray or the like, and is not particularly limited. However, in the present invention, it is necessary to regulate the coating amount to be small, and therefore, it is preferable to use a spray method. Using such a coating method, apply a small amount of resin according to the characteristics of the resin and the surface condition of the roller.A large amount of resin adheres to the peaks on the roller surface, and whether or not it adheres to the valleys. Even if you do, it can be reduced to a very small amount.

[0008]

According to the transfer roller of the present invention, the contamination of the contaminants from the transfer roller surface is extremely small, so that the surface contamination of the photosensitive drum can be minimized. In addition, since there is no toner that easily separates, cleaning of the photosensitive drum is easy or unnecessary. The reason is that the surface roughness of the transfer roller is larger than the toner particle size,
In addition, since the valleys on the surface are not coated with a fluororesin or the like, it is considered that a small amount of toner enters the valleys and is fixed, thereby preventing contaminants from escaping through air bubbles. Further, it is considered that the toner does not easily adhere to the hills or the toner coated with a fluororesin or the like, so that the necessity of cleaning the photosensitive drum is reduced.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/16 103 F16C 13/00

Claims (3)

(57) [Claims] 1. A transfer roller for use in an electrophotographic apparatus comprising a foamed elastic material wound around a cored bar, wherein the surface roughness of the roller surface is larger than the average particle size of the toner used, and The surface is partially coated with fluororesin or silicone resin in the form of fine patches, that is, many resins adhere to the peaks of the surface roughness, and do not adhere or adhere to the valleys. A transfer roller characterized in that the transfer roller is very small. 2. An elastic body containing a foaming agent wound around a cored bar is foamed in a mold so that the average bubble diameter is not smaller than the average diameter of the toner to be used. Remove and remove the skin layer formed on the outer peripheral surface to form a size not less than the average particle size of the toner using the surface roughness, and,
The roller surface is coated with fluororesin or silicone resin so that it is partially covered in fine patches, i.e., a large amount of resin adheres to the peaks of the surface roughness, and there is no or no adhesion to the valleys. A method for producing a transfer roller, characterized in that the transfer roller is kept in a very small amount. 3. The method according to claim 2, wherein spray coating is used for the coating according to claim 2.