JPH06124039A - Production of toner carrying member - Google Patents

Abstract

PURPOSE:To enable the inexpensive mass production of the toner carrying member which can form a closed microelectric field on its surface by mixing two kinds of metallic particles varying in m. p. from each other and sintering the mixture, then heating the mixture to melt, thereby removing the low melting metallic particles. CONSTITUTION:Two kinds of metallic materials having the m. p. varying from each other are mixed. A conductive base 1 is circumferentially coated with such powder mixture. The coating is then press-formed and sintered. The sintered body is heated in the temp. region higher than the m. p. of the low melting metallic particles 13 and lower than the m. p. of the high melting metallic particles, the low melting metallic particles 13 are melted and removed thereby the low melting metallic particles 13 are melted and removed. As a result, the porous sintered body is obtd. around the conductive base 1. The porous gap parts of the porous sintered body are thereafter impregnated and stuck with a resin material melted by heating from its surface later part of the porous sintered body and the resin material is cooled to solidify. The surface layer part is cut off to be flat. The parts constituted by the high melting metallic particles 12 and the resin material are mixedly exposed as flat conductive surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a toner carrier which carries and conveys toner for electrostatic latent image visualization by being rotationally driven.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, a laser printer or a facsimile, which obtains a recorded image by visualizing an electrostatic latent image formed on a latent image carrier, the electrostatic latent image can be formed. Various types of developing devices are used for visualization. Among such developing devices, there is known one that uses a roller-shaped or belt-shaped toner carrier. The toner carrier is rotatably driven in one direction, and while carrying toner on its outer peripheral surface,
The toner is conveyed to a developing area between the toner carrier and the latent image carrier, and the carried toner visualizes the electrostatic latent image formed on the latent image carrier.

In this type of developing device, the toner is charged by, for example, friction between the toner supply roller that supplies the toner to the toner carrier and the toner, or friction between the toner and the toner carrier. However, in order to obtain a higher quality recorded image, sufficiently charge the toner,
It is necessary to carry a large amount of it on the toner carrier.

[0004] A technique for solving such a problem has already been proposed by the present applicant.

This technique forms a large number of minute closed electric fields on the surface of a toner carrier as disclosed in Japanese Patent Laid-Open No. 3-288873. Such a toner carrier is, for example, a roller-shaped conductive support, the surface of which is subjected to square groove knurling, and a grid-shaped recess is formed on the surface.
A resin material, which is a dielectric, is coated around the conductive support so that the recess is completely filled, and the coated material is dried and solidified. It is prepared so that the conductive support portion is exposed.

As shown in FIG. 7, the surface of the toner carrier thus produced has a lattice-like dielectric portion 101.
And a diamond-shaped conductor portion 102 are mixed with each other in a very small area, and the dielectric portion 101 is charged to a polarity opposite to the charging polarity of the toner, for example. 8 is shown in FIG.
Is a cross-sectional view taken along line XX of FIG. 7, and as shown in the figure, a large number of minute closed electric fields E are formed on the surface of the toner carrier 100 by the charging of the dielectric portion 101. Due to the heel-closed electric field, the toner charged to a sufficient strength is strongly attracted to the surface of the dielectric portion 101, and a large amount of the toner is held on the toner carrier 100 in a state where it is difficult to separate. In any case,
A sufficiently charged toner can be carried on the toner carrier in a required amount and evenly, whereby a high-quality visible image with sufficient density without unevenness can be obtained.

However, according to the above-described method for manufacturing the toner carrier, the conductor portions 102 are regularly arranged, and even if one portion is missing, an image defect is caused. Therefore, knurling of the square groove 103 (FIG. 8) must be performed with great care, which requires a long processing time and is not suitable for mass production.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner carrier capable of forming a minute closed electric field on the surface at low cost.
Another object of the present invention is to provide a method for manufacturing a toner carrier which can be mass-produced.

[0009]

In order to achieve the above object, the present invention provides a method for manufacturing a toner carrier for carrying and conveying toner for electrostatic latent image visualization by being rotationally driven. , Two kinds of metal particles having different melting points from each other are mixed, the mixture is pressure-molded around a conductive support, and this is sintered, and then the sintered body is mixed with the melting point of the low-melting metal particles. Above, by heating at a temperature lower than the melting point of the high-melting-point metal particles and melting and removing the low-melting-point metal particles, a porous sintered body is obtained on the conductive support, and this porous sintered body is obtained. The porous void portion of the body is impregnated with the molten resin material from the surface layer portion of the porous sintered body, and after curing, the portion constituted by the refractory metal particles serves as a smooth conductive surface, and the resin material is Similarly, as a smooth dielectric surface, the outer surface on each As mixed exposed to, it is to propose a method for producing a toner carrying member scraping the surface layer portion.

It is effective to heat the sintered body in a vacuum.

It is also effective to heat the sintered body by blowing a compressed inert gas onto the sintered body.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a conductive support serving as a base material of a toner carrier, a mold structure for producing the toner carrier, and the like, and reference numeral 1 has shaft portions at both ends. 2 shows a roller-shaped conductive support. FIG. 5 is a perspective view showing the configuration of this conductive support. The following mixture is coated around the conductive support 1 and pressure-molded.

That is, two kinds of metal particles having different melting points are mixed, and the mixture is coated around the conductive support 1 and pressure-molded. Furthermore, specifically,
Mixing two kinds of metal material powders having different melting points,
The mixed powder is coated around the conductive support 1, pressure-molded, and then sintered. In FIG. 1, reference numerals 2 and 3 respectively indicate an upper mold and a lower mold for press-molding the mixed powder.

In the figure, reference numeral 12 indicates high melting point metal particles, and 13 indicates low melting point metal particles. FIG. 2 is an enlarged schematic view of the metal particles. The hatched circles are the high melting point metal particles 12, and the white circles are the low melting point metal particles 13.

The particles 12 and 13 may be of any kind of metallic material, but examples of the high melting point metallic material include iron (melting point 1535 ° C.) and copper (melting point 1085 ° C.). . Further, as the low melting point metal material, for example, lead (melting point 327.5 ° C.) or tin (melting point 232) is used.
Etc.), and at least the metal material having a high melting point needs to have conductivity.

The particle size of the metal powder before sintering varies depending on the particle size of the toner used and the image characteristics, but is 50
A preferable example is one having a thickness of about 200 to 200 μm. Further, as the material of the conductive support 1,
Metals having a relatively high melting point such as iron, stainless steel, and aluminum are desired. A bias voltage is applied to the conductive support 1 in order to form a predetermined developing electric field with the latent image carrier when the completed toner carrier is used. It may also be grounded. For this reason, the support 1 is made of a conductor.

As described above, the mixed powder is pressure-molded on the conductive support and the molded product is sintered. Next, the sintered product is mixed with the low melting point metal particles 13. The low melting point metal particles 13 are melted and removed by heating in a temperature range that is equal to or higher than the melting point and is lower than the melting point of the high melting point metal particles 12. As a result, a porous sintered body is obtained around the conductive support 1.

It is effective to heat the sintered body in a vacuum to accelerate the removal of the low melting point metal 13.
That is, when the low melting point metal is melted, it is effectively and easily vaporized. In addition to this, the low melting point metal can be efficiently removed even if a compressed inert gas is blown onto the surface of the sintered body during heating.

When the low melting point metal particles 13 shown in FIG. 2 disappear, this portion becomes a porous void portion. That is, as described above, a porous sintered body is formed on the conductive support 1.

After that, the resin material that has been heated and melted is impregnated and adhered to the above-mentioned porous voids from the surface layer portion of the porous sintered body, and is cooled and solidified.

In FIG. 3, numeral 11 indicates a cured resin material. As the resin material of this type, either a thermoplastic resin or a thermosetting resin can be used, and the resin is a dielectric material having a volume resistivity of 10 ¹⁰ Ω · cm or more. Is required. However, in the case of thermosetting resin,
After the adhesion, it is necessary to heat and cure the sintered body impregnated with the resin material in a heating furnace or the like.

By the way, the toner carried around the toner carrier of this kind is roughly classified into two types, that is, a toner having magnetism and a toner having no magnetism. When the latter non-magnetic toner among them is used, a clearer color image can be obtained as compared with the case where a toner containing a magnetic material (magnetic toner) is used. Particularly when a magnetic toner is used, the magnetic powder may be mixed with two types of metal powder. In any case, the present invention can be applied not only to non-magnetic toner but also to a toner carrier that carries and conveys magnetic toner.

When selecting the type of resin material, it is necessary to pay attention to the charging characteristics of the toner. For example,
If a non-magnetic toner is used as the toner and the toner is a material that is easily charged with a positive charge, the resin material to be impregnated is used that is easily charged with a negative charge. Examples of this include materials such as polypropylene, polyethylene, polyphenylene sulfide, and polystyrene.

On the contrary, when the non-magnetic toner is made of a material which easily bears a negative charge, the resin material to be impregnated is one which easily carries a positive charge. An example of this is
Polyamide type (nylon 66, nylon 6, nylon 1
1, nylon 12, etc.), polymethylmethacrylate, polyacrylonitrile, epoxy resin, polyurethane and the like.

By using such a material as the resin material, the triboelectric chargeability with the non-magnetic toner is improved, and a sufficiently charged toner can be conveyed in a large amount, so that a higher quality image can be obtained. Is obtained.

Here, as a method of impregnating and adhering the resin material to the surface of the porous sintered body, it is possible to adopt an injection molding method. For example, a resin material is impregnated and adhered using an injection molding die as shown in FIG.

Reference numeral 1'denotes a conductive support having a porous sintered layer on the outer periphery thereof. This conductive support 1 '
Is set between a pair of molds 4 and 5, and the resin melted by heating is injected and filled into the cavity 6.
In this way, the resin is impregnated and adhered to the surface of the porous sintered body, and then cooled and solidified.

FIG. 3 shows the resin material 1 as described above.
1 is an enlarged cross-sectional view of a surface layer portion of a sintered body obtained by impregnating and curing No. 1 and the surface layer portion after the curing is scraped off by cutting, grinding, polishing or the like. The term "shaving off" includes removal by other methods such as chemical and electrical methods and other methods.

When the surface layer portion is ground flat by various methods as described above, the cut surface of the refractory metal particles is exposed as shown in FIG. In any case, the portion constituted by the high-melting-point metal particles 12 serves as a smooth conductive surface, and the resin material 11 also serves as a smooth dielectric surface so that they are exposed to the outside on the same surface. Of.

Reference numeral 11 'indicates a dielectric surface (dielectric portion) where the resin material 11 is exposed, and 12' indicates refractory metal particles 12 '.
Shows the exposed conductive surface (conductor part).
Between 1'and 12 ', when the toner carrier is used, the minute closed electric field described above is formed. At that time, the conductive surface 1
2'is in a state of being electrically connected to the conductive support 1.

As the above-mentioned surface layer scraping method, various methods such as a cutting method, a grinding method, a polishing method and the like are selected and adopted. In this case, the surface required for the toner carrier is selected. The method will be selected and specified depending on how the roughness becomes.

In addition, regarding the area ratio between the dielectric surface 11 'and the conductive surface 12', first, when two kinds of metals having different melting points are sintered on a conductive support, the metal powders of the two are mixed. It can be easily changed by changing the compounding ratio.

The roller-shaped toner carrier, that is, the developing roller, manufactured as described above is incorporated in the developing device so as to face the latent image carrier (not shown), and is rotationally driven in one direction. The toner for carrying the visible image of the electrostatic latent image is carried and carried.

For example, when a non-magnetic toner is used in this developing device, a toner supply roller is arranged so as to come into contact with the toner carrier that is rotationally driven, and the toner is stored in the developing device by the rotation of this supply roller. The toner contained in the case is supplied to the toner carrier. During such an operation, the toner is triboelectrically charged to a predetermined polarity, and the dielectric surface 11 'of the toner carrier is triboelectrically charged, for example, to a polarity opposite to the charging polarity of the toner. This allows the dielectric surface 1
A minute closed electric field (see FIG. 8) is formed between 1'and the conductive surface 12 ', and a large amount of toner adheres to the toner carrier due to the action of the strong electric field, and the toner is carried by the rotation of the carrier. The body and the latent image carrier (for example, photoconductor) are conveyed to a developing area where they oppose each other, and the toner is electrostatically transferred to the electrostatic latent image on the latent image carrier 2, and the latent image can be used as a toner image. To be visualized.

As described above, by using the toner carrier in which the dielectric portion 11 'and the conductor portion 12' are mixedly exposed, a large amount of sufficiently charged toner can be carried and transported on the toner carrier. Therefore, it is possible to obtain a higher quality image in which uneven density is less likely to occur. Further, when a non-magnetic toner is carried on such a toner carrier, it is possible to obtain a high-quality color image in which uneven density hardly occurs.

Regarding the structure and operation of the above-described developing device, in addition to the above-mentioned publication, Japanese Patent Application No. 2-275061.
It is also explained in detail in the issue. It is also well known that a toner having an auxiliary agent mixed (externally added) can be used.

The present invention can be applied not only to a roller-shaped toner carrier but also to a method for manufacturing a belt-shaped toner carrier, in which case a belt-shaped or sheet-shaped conductive support is used. It

[0039]

According to the manufacturing method of the first aspect, a toner carrier capable of forming a minute closed electric field on the surface can be inexpensively mass-produced.

According to the manufacturing method of the second and third aspects, the low melting point metal particles can be easily removed.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a conductive support which is a base of a toner carrier, a mold structure for producing the toner carrier, and the like.

FIG. 2 is an enlarged schematic view of two types of metal particles.

FIG. 3 is an enlarged cross-sectional view of a surface layer portion of a sintered body in which a resin material is attached to a porous sintered body.

FIG. 4 is an enlarged cross-sectional view of a sintered body surface layer portion in which the surface layer portion of the sintered body is scraped off to expose a dielectric surface and a conductive surface in a mixed manner.

FIG. 5 is a perspective view showing a configuration example of a conductive support.

FIG. 6 is a cross-sectional configuration diagram showing an example of an injection molding die for impregnating a resin material.

FIG. 7 is an enlarged view of the surface of a toner carrier obtained by a conventional method.

FIG. 8 is a cross-sectional view taken along line XX of FIG.

[Explanation of symbols]

 1 Conductive Support 11 Resin Material 12 High Melting Point Metal Particles 13 Low Melting Point Metal Particles 11 'Dielectric Surface 12' Conductive Surface

Claims (3)

[Claims] 1. A method of manufacturing a toner carrier for carrying and conveying toner for visualizing an electrostatic latent image by being rotationally driven, wherein two kinds of metal particles having different melting points are mixed, This mixture is pressure-molded around a conductive support, and after sintering, the sintered body is at least the melting point of the low melting point metal particles and lower than the melting point of the high melting point metal particles. By heating at a temperature and melting and removing the low melting point metal particles, a porous sintered body is obtained on the conductive support,
The porous voids of this porous sintered body are impregnated with the molten resin material from the surface layer of the porous sintered body, and after curing,
The surface layer portion is scraped off so that the portion constituted by the high-melting-point metal particles serves as a smooth conductive surface and the resin material serves as a smooth dielectric surface so as to be mixedly exposed to the outside on each surface. Method for manufacturing toner carrier. 2. The method for producing a toner carrier according to claim 1, wherein the sintered body is heated in a vacuum. 3. The method for producing a toner carrier according to claim 1, wherein the sintered body is heated by blowing a compressed inert gas onto the sintered body.