JPH06130794A - Method for manufacturing toner carrier - Google Patents

Abstract

(57) [Abstract] [Purpose] A toner carrier in which a conductor portion and a dielectric portion are dispersed and exposed on the surface is manufactured inexpensively in a short process time and in a large amount without using an adhesive. It is an object of the present invention to provide a method of manufacturing a toner carrier which is made possible. Constitution: Around the conductive support 1, a mixture of a powder of conductive resin particles 5 and a powder of dielectric resin particles 6 is coated. While leaving the particles 6, the former conductive resin is melted to form a conductive resin film layer, and then the film layer is ground.

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, for example, the toner is charged by friction between the toner supply roller for supplying the toner to the toner carrier and the toner, friction between the toner and the toner carrier, or the like. However, in order to obtain a higher quality recorded image, it is necessary to sufficiently charge the toner and convey it in large amounts on the toner carrier.

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

This technique is disclosed, for example, in Japanese Patent Laid-Open No. 3-28887.
As disclosed in Japanese Patent Publication No. 3, a large number of minute closed electric fields are formed on the surface of the toner carrier. Such a toner carrier is a dielectric so that, for example, the surface of a roller-shaped conductive support is subjected to square groove knurling, and lattice-shaped concave portions are formed on the surface so that the concave portions are completely filled. A resin material is coated around a conductive support, the coated material is dried and solidified, and then the resin coating layer is cut or polished to expose the conductive support portion of the content. To be done.

As shown in FIG. 8, the surface of the toner carrier thus produced has a lattice-like dielectric portion 101.
And the diamond-shaped conductor portions 102 are mixed with each other, and the dielectric portion 101 of these is charged, for example, to a polarity opposite to the charging polarity of the toner. FIG. 9 is a sectional view taken along the line XX of FIG. 8, and as shown in FIG.
A large number of minute closed electric fields E are formed on the surface of 00 due to the charging of the dielectric portion 101 described above.

Due to the 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 so that it cannot be easily separated. In this way, a sufficiently charged toner can be carried on the toner carrier in a required amount and evenly, and the toner is conveyed to the developing area between the toner carrier and the latent image carrier, With the toner, the electrostatic latent image formed on the latent image carrier can be visualized as a toner image, and 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, the knurling of the square groove 103 (FIG. 9) must be performed with great care, which requires a lot of processing time and is not suitable for mass production.

At least a first adhesive layer, a conductive particle layer, and a second adhesive layer are sequentially formed on a conductive support, and then the surface is ground to form at least a part of the conductive particles. The present applicant has proposed a method of manufacturing a toner carrier in which the above is exposed (see, for example, Japanese Patent Publication No. 2-15066). The toner carrier shown here does not form a large number of minute closed electric fields on the surface thereof, and the configuration of the conductive portion and the dielectric portion is opposite to that of the toner carrier targeted by the present invention, The toner carrier targeted by the present invention can also be manufactured in the same manner as the idea disclosed in this publication.

However, according to the method disclosed in this publication,
Since an adhesive layer for holding the conductive particles or an adhesive layer held on the conductive particles is required, it takes a lot of time to apply the adhesive for forming the adhesive layer. However, there is a drawback that the manufacturing cost becomes high. In addition, it is difficult to completely bond the conductive particles, and the particles may be detached in a later grinding step or the like, resulting in an image defect.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner carrier in which a conductor portion and a dielectric portion are dispersed and exposed on the surface, at a low cost and in a short process time without using an adhesive or the like. Moreover, it is another object of the present invention to provide a method for manufacturing a toner carrier that can be manufactured in large quantities.

[0012]

In order to achieve the above object, the present invention is a method of manufacturing a toner carrier for carrying and conveying toner for electrostatic latent image visualization by being rotationally driven. In, a conductive resin and a powdery mixture in which a dielectric resin having a higher melting point is mixed with each other are applied around the conductive support to cover the conductive resin, By heating at a temperature at which only the resin melts, a conductive resin film layer containing a dielectric resin is formed around the conductive support, and the conductive resin film layer is formed at or near the melting point of the dielectric resin. After heating to the temperature of, and then cooling this, the conductive resin film layer as a conductor portion,
The present invention proposes a method for producing a toner carrier in which the conductive resin film layer is scraped off so that the dielectric resin is exposed as a dielectric portion on the surface.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a roller-shaped conductive support having shafts 1a (the other is not shown) at both ends,
The support 1 serves as a base of the completed toner carrier. When such a toner carrier is used, in order to form a predetermined developing electric field between the latent image carrier (not shown) facing the toner carrier, a bias voltage is applied to the conductive support 1 or the conductive support 1 is grounded. To be done. For this reason, the support 1 is made of a conductor.

The first step in the method of manufacturing a toner carrier according to the present invention is a mixing step (see FIG. 7).

That is, as shown in FIG. 2, a powdery conductive resin and a powdery dielectric resin are put in the mixer 2, and the stirring blades 3 inside rotate. The two resins are mixed with each other and are uniformly dispersed.

When the completed toner carrier is used, when the toner carried and conveyed by the carrier is, for example, one that is triboelectrically negatively charged, as the dielectric resin,
A polyamide resin having a positive polarity, which has a polarity opposite to that of the toner, is easily frictionally charged. For example, this resin series "nylon 6" can be used. For the reason described later, when a similar polyamide resin is used as the conductive resin, the resin series "nylon 12" or the like in which carbon is dispersed is crushed into a powder. Any thing can be used.

In this case, if the amount of carbon added is unnecessarily large, the adherence rate of the powdery conductive resin will decrease during the electrostatic coating process described below, so the amount added will be adjusted appropriately. It is necessary to add carbon so that the volume resistivity of the powdery conductive resin is about 10 ⁶ Ω · cm.

The particle size of both resins is 50 to 200 in each case.
When the conductive resin is "nylon 12" and the dielectric resin is "nylon 6", the melting point of the former is about 175 ° C and the melting point of the latter is higher than that. It is about 215 ° C. The temperature difference of the melting points is 40 ° C.

The mixing ratio (weight ratio) of both powder resins can be set to, for example, 4: 6 (conductive resin: dielectric resin), but depending on the characteristics of the toner carrier.
It is desirable to set the mixing ratio range of 3: 7 to 5: 5.

The mixture having such a mixing ratio is supplied to the hopper of an electrostatic coating machine (not shown) (see FIG. 7).
A voltage of, for example, -30 KV is applied to the electrostatic coating machine, and as a result, as shown in FIG. 3, the mixture (electrically conductive resin powder particles 5) from the above-mentioned mixture is discharged from the nozzle 4 of the electrostatic coating machine.
And powder particles 6 of the dielectric resin) are sprayed, and these are simultaneously applied to the outer peripheral surface of the conductive support 1 by utilizing electrostatic force. By this coating, the mixture is coated around the conductive support 1. That is, this is the "coating step" in the process chart shown in FIG. FIG. 1 is an enlarged schematic view showing only a coating portion on a conductive support.

Next, the coating on the conductive support 1 is heated at a temperature at which only the conductive resin melts. For example, 190
It is heated at a temperature of ° C. Incidentally, the melting points of both resins are as described above, but are as follows. Conductive resin (nylon 12) → 175 ° C Dielectric resin (nylon 6) → 215 ° C

By heating the coating material at a temperature of 190 ° C., the conductive resin powder particles 5 are brought into a molten state, and the dielectric resin powder particles 6 remain as particles without being melted. In any case, the powder particles 5 of the conductive resin are melted to form a film as shown in FIG. In this way, the conductive resin film layer 15 formed around the conductive support 1 contains the powder particles 6 of the dielectric resin. This is the film forming process shown in FIG.

Next, after the film forming step, the conductive resin film layer 15 (FIG. 4) in which the powder particles 6 of the dielectric resin are contained is formed at or near the melting point of the powder particles 6 of the dielectric resin. Heat to the temperature of. For example, heating is performed at a temperature of 210 ° C. to 220 ° C., which is close to the melting point of the dielectric resin. This is Figure 7
Is the heating step.

In this heating step, the molten conductive resin and the particles 6 of the dielectric resin are fused to each other while maintaining the particle shape (island shape) of the dielectric resin. 6 are completely adhered to the conductive resin coating layer 15. The heating temperature at this time is set to a temperature at which the original shape of the particles 6 of the dielectric resin can be maintained and the conductive resin is not deteriorated. If this temperature is raised too high, the particles 6 of the dielectric resin are broken and melted into a state in which the conductive resin and the conductive resin are mixed together. Is set.

When a polyamide resin is used for both the conductive resin and the dielectric resin, the compatibility between the two becomes good, so that a sufficient fusion bonding force can be secured. On the other hand, when different materials are used for both, it is advisable to select a material having a similar “SP value” called the solubility index.

After the above heating step, the conductive resin film layer 15 (FIG. 4) is cooled and the layer is cured. After this curing, the conductive resin film layer 15 is scraped off by grinding or polishing, and as shown in FIG. 5, the conductive resin film layer 15 serves as a smooth conductor portion and the dielectric resin particles 6 serve as a smooth dielectric material. As a body part, it is exposed on the same surface. This step is the grinding step shown in FIG. In this way
A roller-shaped toner carrier, that is, a developing roller, which carries and conveys toner for forming an electrostatic latent image visible image is completed.

FIG. 6 shows the conductive resin film layer 1 after the grinding process.
5 is an enlarged partial sectional view of FIG. 5, in which the island-shaped dielectric resin particles 6 are randomly dispersed and exposed in the underlying conductive resin film layer 15. In any case, the conductor portion 5 '
And the dielectric portion 6'is dispersed and exposed,
When the toner carrier is used, a minute closed electric field is formed between them.

The toner carrying member produced as described above is incorporated into a developing device so as to face a latent image carrying member (not shown), and is rotated in one direction to generate an electrostatic latent image. The toner for visualizing is carried and conveyed.

For example, in this developing device, when a non-magnetic toner is used, a toner supply roller is arranged so as to come into contact with the toner carrier that is rotationally driven, and the toner of the developing device is rotated by the rotation of this supply roller. The toner contained in the containing case is supplied to the toner carrier. During such an operation, the toner is triboelectrically charged to a predetermined polarity, and the dielectric portion 6'on the surface of the toner carrier is also triboelectrically charged to the opposite polarity to the charging polarity of the toner. As a result, a minute closed electric field (see FIG. 9) is formed between the dielectric portion 6'and the conductor portion 5 ', and a large amount of toner adheres to the toner carrier due to the action of the strong electric field. By the rotation of the body, the toner carrier and the latent image carrier (for example, photoconductor) are conveyed to the developing area where they face each other, and the toner electrostatically transfers to the electrostatic latent image of the latent image carrier, and The image is visualized as a toner image.

By using such a toner carrier in which the dielectric portion 6'and the conductor portion 5'are mixedly exposed, a large amount of sufficiently charged toner can be carried and conveyed on the toner carrier. It is possible, and uneven density is less likely to occur,
A higher quality image can be obtained.

Further, when a non-magnetic toner is carried on such a toner carrier, a high quality color image in which uneven density is less likely to occur can be obtained. However, a magnetic toner is used and this is carried out by the toner carrier. It can also be transported to the development area.

Regarding the structure and operation of the above-mentioned 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.

In the above manufacturing method, a step of mixing the powdery conductive resin and the powdery dielectric resin is provided, but each particle of the powder is a conductive resin part. It is also possible to use a resin powder composed of, for example, encapsulated particles, which is composed of a resin and a dielectric resin portion, and to directly jet this from the nozzle 4 (FIG. 3) of the electrostatic coating machine. In this case, the mixing process becomes unnecessary. In any case, a powdery mixture in which a conductive resin and a dielectric resin having a higher melting point are mixed together is applied and coated around the conductive support.

According to the manufacturing method described above, an adhesive agent for adhering the dielectric resin particles is not required, so that the pretreatment of the dielectric resin particles and the adhering step thereof are not necessary, and the conductor portion and Since the dielectric part can be formed at the same time, a large amount of toner carrier can be manufactured at a low cost in a shorter process time. Moreover, since the dielectric resin particles are less likely to fall off during grinding or the like, there is no possibility of causing an image defect or the like.

Further, according to the present manufacturing method, the mutual area of the conductive portion and the dielectric portion of the completed toner carrier is changed only by changing the mixing ratio of the powders of the conductive resin and the dielectric resin. The ratio can be freely changed, and the toner charge amount and the like can be skillfully controlled.

By the injection molding method or the resin molding method,
Although it is possible to form the resin layer in the form of a film, according to this method, when an external force is applied to the conductive support at the time of this film formation, and the conductive support is made tubular for further weight reduction. For example, the conductive support may be deformed,
In the present manufacturing method, since such an external force is not applied, there is no possibility of causing such deformation. The conductive support may be a thin-walled tubular support.

The volume resistivity of the conductive resin used in the present invention is determined in consideration of the manufacturing conditions of the toner carrier and the strength of the minute closed electric field formed on the surface of the completed toner carrier. In the above embodiment, this is set to 1
It was set to about 0 ⁶ Ω · cm. Generally, a conductive resin having a volume resistivity of 10 ⁷ Ω · cm or less, preferably 10 ⁶ Ω · cm or less is 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

[0040]

According to the method of manufacturing a toner carrier according to the first aspect of the present invention, the step of adhering the dielectric resin particles is not necessary, so that the toner carrier can be manufactured in a large amount at a low cost in a shorter process time. Can be made. Further, it is possible to manufacture a toner carrier which does not cause the dielectric resin particles to fall off which causes image defects.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a conductive support which is a base of a toner carrier obtained by a manufacturing method of the present invention.

FIG. 2 is a schematic cross-sectional configuration diagram of a mixer for mixing a powdery conductive resin and a dielectric resin.

FIG. 3 is a schematic explanatory view showing a coating process of a mixture of a conductive resin powder and a dielectric resin powder.

FIG. 4 is a partial cross-sectional explanatory view showing a state in which the above mixture is formed into a film and coated on a conductive support.

FIG. 5 is a diagram showing a state after a grinding step of a coating of a conductive support.

FIG. 6 is an enlarged cross-sectional view of a toner carrier surface layer portion in which a conductor portion and a dielectric portion are exposed.

FIG. 7 is a diagram showing a manufacturing process of a toner carrier.

FIG. 8 is an enlarged schematic view of a dielectric portion and a conductor portion of a surface layer portion of a toner carrier obtained by a conventional method.

FIG. 9 is a diagram showing a state in which a minute closed electric field is formed on the surface of a toner carrier obtained by a conventional method.

[Explanation of symbols]

 1 Conductive Support 5'Conductive Part 6'Dielectric Part 15 Conductive Resin Film Layer

Claims (1)

[Claims] 1. A method for manufacturing a toner carrier for carrying and conveying toner for visualizing an electrostatic latent image by being rotationally driven, comprising a conductive resin and a dielectric material having a melting point higher than that of the conductive resin. A powdery mixture in which the resin and the resin are mixed with each other is applied and coated around the conductive support, and the coating is heated at a temperature at which only the conductive resin is melted to remove the dielectric resin. A conductive resin film layer included is formed around a conductive support, and the conductive resin film layer is heated to a temperature at or near the melting point of the dielectric resin, and then cooled, and then the conductive resin The resin film layer is the conductor part,
A method of manufacturing a toner carrier, characterized in that the conductive resin film layer is scraped off so that the dielectric resin is exposed as a dielectric portion on the surface.