JPS58202457A - Electrostatic image developing carrier - Google Patents

Abstract

PURPOSE:To obtain a long-lived carrier suitable high speed copying machine, by suspending the core material of the carrier of a dry type 2-component type developer, spraying a surface-coating liquid, drying it at high temp., and repeating these operations to form a scale-like surface coat layer. CONSTITUTION:The carrier core material 4 is fed into a fluidized bed chamber 1, a gas is fed from below with a blower 3, and the material 4 is stirred with a rotary disc 8 to promote fluidization. The liquid coating 5 consisting of a solution of styrene (co)polymer, acrylic resin, or the like thermoplastic resin, polyester, melamine resin, or the like thermosetting resin, and necessary conductive agent, charging controller, etc. is sprayed from a spray nozzle, and dried at 80-90 deg.C with a heater 6. It takes about 5min to spray the coating 5, and 5- 10min to perfectly dry it. This operation is repeated in necessary times, such as 10-100 times, to coat the resin like scales. The carrier having the surface coat layer 7 thus obtained is stipped little by little during use, and an always fresh surface is disclosed, maintaining charging characteristics always uniform, and having a life longer than the conventional carriers. The stripped fine scales are removed together with the toner from a developing device, and the scales do not be stripped much in one time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry developer key 7 used for visualizing an electrostatic latent image formed by electrophotography, electrostatic recording, electrostatic printing, or the like. Regarding improvements.

So-called two-component dry developers comprising a mixture of carrier particles and toner particles have been well known. In this two-component dry type adjuvant, minute toner particles are held on the surface of relatively large carrier particles by electric force generated by friction between both particles, and when brought close to an electrostatic latent image, electrostatic The attraction force toward the toner particles in the @latentllIh direction due to the electric field formed by the latent image overcomes the bonding force between the toner particles and the carrier i particles, and the toner particles are attracted and adhered to the electrostatic latent image, forming an electrostatic latent image. is visualized. and,
The developer is used repeatedly while replenishing the toner consumed by development.

Therefore, the carrier must constantly triboelectrically charge the toner particles to the desired polarity and sufficient charge during long-term use. However, in the conventional developer 2, toner scum is formed on the surface of the gear 9 due to mechanical collisions such as collisions between particles or collisions between particles and the developing machine, or heat generated by these, resulting in so-called spent state, and the carrier is closed. The charging characteristics deteriorate with time of use, resulting in frequent replacement of the entire developer.

In order to prevent such spent formation, methods of coating the carrier surface with various resins have been proposed, but no satisfactory method has yet been obtained. For example, KiV 7 coated with resin such as styrene-methacrylate copolymer or styrene polymer has excellent charging characteristics, but
The critical surface tension of the surface is relatively high, and as it undergoes repeated copying, it will eventually become bent, so its lifespan as a developer is not very long. In addition, since the carrier coated with tetrafluoroethylene polymer has a low surface tension, it is difficult for t- to become spent, but since the tetrafluoroethylene polymer is also located on the negative side of the triboelectrification series, green is also located on the negative side. It cannot be used when attempting to charge toner to a negative polarity. It is also being considered to coat it with silicone resin as a material with low surface tension.

However, since silicone resin itself has low mechanical strength, 1797 particles may collide with the inner wall of the developing section or the surface of the photoreceptor, or be exposed to scratches or The silicone resin is scraped off by the collision of the same number of jν particles, and if the film is stirred for an even longer period of time, the coating disappears, and the frictional electrification of the developer is caused by the toner and the charge between the silicone resin and the toner and the core material. The amount of charge on the developer remains constant because the charge changes to . , :
Therefore, the image quality also deteriorates.

The present invention has been made in view of the above points, and its gist is to provide an electrostatic image developing method in which a carrier for a dry two-component developer is characterized in that the surface coating layer is scale-like. The carrier core material is suspended using a carrier for the agent and a fluidized bed method, and a coating liquid is sprayed onto the carrier core material, which is then dried at a high temperature. This is a method for producing F-V rear for electrostatic image developer.

In the present invention, the coating layer of the carrier is made to be scaly, and when this carrier is used as a developer together with toner, the scaly [-1.-] on the surface peels off a little.
A surface similar to that of a sword appears in the developing middle shrine. Therefore, no deterioration due to spent toner is observed, and a decrease in charging ability can be prevented. Further, the peeled off coating film is generally colorless or white, and does not cause any undesirable effects such as scumming even if it adheres to the copy. Furthermore, the toner is fine to begin with and becomes even finer within the developing section, and is discharged to the outside together with the toner being developed, so it does not contribute to the deterioration of the agent. Furthermore, even if a particularly large force is applied to the carrier, the entire surface will not peel off at once, and the function of the carrier will not be completely lost. The lifespan of this carrier is the point at which the coating film is completely peeled off, but the lifespan can be controlled quite freely depending on the thickness of the coating film. The timing of replacement will also be clear.

The materials of the coating layer according to the present invention include styrene resin, styrene/acrylate copolymer resin, acrylic resin, amide resin, polyester resin, urea resin,
Thermoplastic or thermosetting resins such as melamine resins and epoxy resins can be used. Alternatively, photocurable resins such as polyvinyl cinnamate, simpmoyl polystyrene, and ethylene vinyl cinnamate copolymers can also be used. A conductive agent, a triboelectricity control agent, a crosslinking agent, etc. may be optionally added to these materials.

In the manufacturing method of the present invention, the carrier core material is suspended by the fluidized bed method, and the coating liquid is sprayed from above and dried at a high temperature of 80 to 90°C. Allow time for drying. Usually about 5 to 10 minutes. Further, the amount of spraying of the coating liquid at one time is such that it can cover the surface of the carrier core material by 30 to 50%.

By repeating the spraying and drying of the coating solution a number of times, usually 10 to 100 times, a scaly surface coat (2) of a desired thickness can be obtained.

Examples will be described below based on the drawings.

FIG. 1 is a conceptual diagram of aA@ for carrying out the method of the present invention, in which 1 indicates a fluidization bed chamber, 2 a spray nozzle, and 3 a blower. In the fluidization bed chamber 1, there is a rotating disk 8.
The carrier core material 4 is stirred and gas is introduced from below using a blower 3 to make the carrier core material 4 float and flow in the room. The coating liquid 5 is sprayed there from the spray nozzle 2, and the coating liquid 5 adhering to the surface of the carrier core material 4 is dried.

FIG. 2 is a model cross-sectional view of the 11 Yaria according to the present invention. That is, the surface of the carrier core material 4 has a scale-like surface [l
il]-t 117 is formed.

To give a specific example, 50 kg of 100μ carrier core material 4 was used, and coating liquid 5 was applied to the carrier core material 4.
Approximately IKo of styrene/methyl methacrylate copolymer made into a 0% solution is applied at a temperature of 80°C. Then pause the spray for about 5 minutes. This process is repeated until the 40KO coating liquid is used up. In this way, a surface coating layer of approximately 3 μm in thickness of about 8 to 101 layers is obtained.

A copying test was conducted using the carrier obtained above, and the results shown in the table below were obtained. The comparative product is an example using a conventional carrier with the same surface coating layer material and -.

Table star t-01,1001,09 500001,1101,05 1000001,0801,01 2000001,05Δ 0.9630000
0 1.12 x 0
08040000 x O,81x
As clearly shown above, the image quality of the product of the present invention is very stable up to 30,000 sheets;
The comparative product deteriorates little by little after 10,000 sheets.

In the case of the product of the present invention, the agent deteriorates rapidly after 30,000 sheets, and it is clear when to replace it.

[Brief explanation of the drawing]

FIG. 1 shows a conceptual diagram of an apparatus for carrying out the invention, and FIG. 2 shows a model sectional view of the carrier of the invention. 1...Fluidization bed chamber 2...Spray nozzle 3...Blow two 4...Carrier core material 5...Coating liquid 6... ...Heater 7.
...Surface-1-T layer 8 ...Rotating disk patent applicant Ricoh Co., Ltd. Patent attorney Hidetake Komatsu ↑ 1 Figure - Ir2 diagram

Claims (2)

[Claims] (1) A carrier for an electrostatic image developer, which is a carrier for a dry two-component developer, and is characterized in that a surface coating layer has a scale-like shape. (2) Floating the carrier core material using the fluidized bed method,
Spray the coating liquid on it, dry it at ^ temperature, and then
A method for producing a carrier for an electrostatic image developer, comprising repeating spraying and drying of a liquid a necessary number of times.