JPS61158111A - Plastic magnet roll - Google Patents

Abstract

PURPOSE:To obtain the title magnet roll having excellent resistance against a temperature change and the high accuracy of finishing by integrally molding the mixture of a fibrous substance, magnetic powder surfacet-treated by a coupling agent and a synthetic resin binder together with a roll shaft. CONSTITUTION:A synthetic resin binder, a fibrous substance and magnetic powder each treated by a coupling agent are mixed regarding a plastic magnet roll 1, and the magnet roll 1 is molded in integral structure together with a roll shaft 3 made of a metal or the whole containing the roll shaft is molded integrally by the same quality of a material. Consequently, a contraction coefficient on a molding is reduced while mechanical strength after the molding is increased, thus preventing the generation of cracks and crazings. Magnetic powder and the fibrous substance are treated severally by the coupling agent, and the surfaces of particles are film-treated and extraneous moisture is removed, thus also obviating the generation of cracks and crazings resulting from the gasification of moisture.

Description

[Detailed description of the invention] (a) Purpose [Field of industrial application] This invention relates to a plastic magnet roll,
For example, it is useful as a magnet roll for magnetic brush development.

[Conventional technology]

Conventional examples of plastic magnet rolls include, for example, Japanese Patent Application Laid-open No. 5
3-94940, JP-A-55-165606 and JP-A-56-108207. These are magnetic rolls for copying machines, and around a metal shaft,
A plastic magnet made of magnetic powder and a synthetic resin binder is formed into an integral structure.

[Problem that the invention seeks to solve]

In conventional magnet rolls, because the thermal deformation rates of the metal shaft and plastic magnet are different, the plastic magnet may break or crack due to temperature changes during manufacturing or use, and the metal shaft may There is a risk that the magnet roll will be deformed by the molding pressure and the residual stress will cause warpage after molding, and it has been subject to the following limitations.

(i) A long roll having a length of 1-11 times larger than its diameter cannot be manufactured by a manufacturing method that involves large temperature fluctuations, such as injection molding, and cannot be used in an environment with large temperature fluctuations.

(ii) In order to make a long roll, it is necessary to lower the mixing ratio of magnetic powder or use a synthetic resin with high ductility as the synthetic resin binder. However, this method has drawbacks such as a decrease in magnetic force and a decrease in heat resistance.

In order to solve the above-mentioned problems, the inventor of this invention
He completed a plastic magnet made of a mixture of a fibrous material surface-treated with a silane coupling agent, magnetic powder surface-treated with a silane coupling agent, and a synthetic resin binder, and filed a patent application. Showa 59-237306
However, as a result of further research on other coupling agents, the present invention was completed.

The present invention provides a plastic magnet roll that has excellent resistance to temperature changes and has high processing accuracy.

(B) Structure of the Invention The present invention is for molding a mixture of a fibrous material whose surface has been treated with a coupling agent, a magnetic powder whose surface has been treated with a coupling agent, and a synthetic resin binder. It has been experimentally found that the molded articles have further improved mechanical properties without compromising their magnetic properties. Thereby, this mixture is integrally molded with a metal roll shaft,
What makes it possible to obtain plastic magnet rolls that do not cause cracks or cracks, and also makes it possible to obtain plastic magnet rolls that can withstand use even when the entire roll shaft, including the roll shaft, is integrally molded from the same material. This is a feature of this invention.

As the above-mentioned fibrous material, glass fiber is preferable from the point of view of cost etc., but carbon fiber, aromatic polyamide fiber,
Whiskers etc. can also be used.

As the magnetic powder, conventionally known magnetic powders can be used, and specific examples include barium ferrite, strontium ferrite, and lead ferrite.

Examples of the coupling agent include a silane coupling agent, an aluminum coupling agent, a titanate coupling agent, and a zircoaluminate coupling agent. Coupling agents for surface treatment of fibrous materials and coupling agents for surface treatment of magnetic powders include combinations of German coupling agents such as titanate coupling agents and titanate coupling agents, as well as silane-based coupling agents. There are different combinations such as coupling agent-aluminum-based coupling agent.

Specific examples of the synthetic resin binder include thermosetting resins such as phenol resins, epoxy resins, and unsaturated polyester resins, thermoplastic resins such as polyamide resins, polyethylene resins, polyethylene terephthalate resins, ABS resins, and ethylene-vinyl acetate copolymers. Examples include resin.

The preferable mixing ratio of the fibrous material, magnetic powder, and synthetic resin binder is: 0.5 to 12% by weight of the fibrous material, 65 to 87% by weight of the magnetic powder, and 12.5 to 23% by weight of the synthetic resin binder.

The mixing ratio of magnetic powder is determined based on magnetic properties, workability, and mechanical strength. Furthermore, if the mixing ratio of the fibrous material is larger than this, the magnetic properties will deteriorate, and if it is smaller than this, no reinforcing effect on mechanical strength will be recognized.

When the above-mentioned fibrous substance is glass fiber, it is preferable that the cut length is 2 to 6 mm and the filament diameter is 5 to 20 μm.If it deviates from these ranges, the reinforcing effect of the molded product may be reduced or the molding process may be affected. The dispersibility with the binder and the fluidity of the mixture are lost.

In addition, the average particle diameter of the above magnetic powder is 045 to 1.5μ
m is preferred. This value was determined based on the orientation characteristics of the powder particles, the combined effect with the binder in terms of mechanical strength, and the wear of the mold during injection molding.

The above-mentioned magnetic powder and fibrous substance are surface-treated with a coupling agent before molding. (3) The bonding properties (mechanical strength) between the binder and the fibrous material and magnetic powder are improved.

The plastic magnet roll of this invention is manufactured by injection molding. In other words, the roll shaft is inserted into the mold, or the roll shaft is integrated with the roll body, and a mixture of magnetic powder, fibrous material, and synthetic resin binder is heated and melted in the space. has been injection filled,
After cooling, it is taken out as a molded product. Note that the plastic magnet roll is magnetized simultaneously with the molding by a magnetizing device provided in the molding die.

It is known that the main cause of cracks in plastic magnet rolls is internal residual stress caused by inhibition of molding shrinkage of the plastic magnet due to the metal roll shaft. In the plastic magnet roll of the present invention configured as described above, its mechanical strength is improved, and in particular, the shrinkage rate during molding and cooling is reduced. Table 1 shows the difference between the glass fiber surface-treated with an aluminum-based coupling agent according to the present invention, the magnetic powder surface-treated with a silane-based coupling agent, and the plastic magnet roll made of a synthetic resin binder, and the conventional one. An example of shrinkage rate during mold cooling is shown.

(The following margins continue on the next page) Table 1 (Roll diameter: 20 mm, roll shaft Ni stainless steel, 8 mm diameter) Figure 1 1a) showing a vertical cross-sectional view of the top of the seed plate, and its A-A cross section. In FIG. 1, (1) is a long magnet roll according to an embodiment of the present invention, which is used by being inserted into a sleeve (4) for development in an electrostatic copying machine. The roll body (2) is made of stainless steel with a diameter of 17.6 mm and a length of 207 m, and the roll shaft (3) is made of stainless steel with a diameter of 6 fi and a shaft length of 256 m. In addition, the sleeve (4) has an inner diameter of 19.6 m and an outer diameter of 21.6 m.
Made of +n aluminum. (5), (6) are flanges attached to both ends of the sleeve (4), (7), (8)
is a metal bearing that supports the roll shaft (3).

The manufacturing method for this magnet roll (11) consists of inserting and fixing the roll shaft (3) into a mold, and adding 6.25% by weight of glass fiber and 6-nylon 18% treated with a coupling agent to the roll shaft (3).
75% by weight and an average particle size of 0 treated with a coupling agent.
．． A mixture of 9 μm barium ferrite and 75% by weight is injected and filled, simultaneously magnetized and molded. After cooling, the molded product is taken out from the mold, its dimensions are corrected, and it is mounted in the sleeve (4). In this case, if the warpage in the axial direction of the magnet roll is less than 0.3, it will be considered defective because it will be difficult to install and a load will be applied to the rotation of the magnet roll. In this example, coupling agents for ferrite treatment and glass fiber treatment were combined as shown in Table 2, and a total of 80 magnet rolls, 10 of each combination, were manufactured, but there were no cracks or cracks. , was not seen in all of them.

Moreover, the warpage in the axial direction was within 0.3R, and all of them were installed in the sleeve (4) without modification.

(Margins below, continued on next page) Table 2 Coupling agent In the longitudinal cross-sectional view shown in FIG. This is a roll used to collect phenomenon toner.

The roll body (12) has a diameter of 14 m and a length of 44 ON.
The roll shafts (13) and (14) have a diameter of 6 fins and a shaft length of 15 fins. Roll body (12) and roll shaft (13)
), (14) are made of 9% by weight of glass fibers and 6-nylon that are integrally molded and treated with a coupling agent.
It contains 21% by weight of barium ferrite and 70% by weight of barium ferrite treated with a coupling agent and having an average particle diameter of 1.0 μm.

The manufacturing method of this magnet roll Ql) is to heat and melt the above mixture of barium ferrite, glass fiber and nylon at 270°C and inject it into a mold that can obtain the finished dimensions of each part described above. It is magnetized.

As a result, 80 magnet rolls were manufactured in the same manner as in Example 1, but no cracks or cracks were observed in all of them.

On the other hand, if a roll with a conventional metal penetrating shaft is manufactured using conventional materials, the dimensional relationship in the above example will result in the total number of rolls exceeding 200 m in length. , Several circumferential cracks were observed in the roll body.

For the 80 magnet rolls, the coupling agents for ferrite treatment and glass fiber treatment were combined as shown in Table 3, and 10 of each combination was manufactured. All samples were investigated after production, and the mechanical properties of each combination of processing coupling agents are shown in Table 4 as average values. According to this, N11L-
11k13, 6 and 11h7 are preferred.

(The following margins continue on the next page) (c) Effects of the invention The plastic magnet roll of this invention is made by mixing a synthetic resin binder with a fibrous material and magnetic powder each treated with a coupling agent. It is integrally formed with the roll shaft, or the entire body including the roll shaft is integrally molded of the same material. Therefore, the shrinkage rate during molding is reduced and the mechanical strength after molding is improved, so that cracks and cracks are prevented from occurring.

Furthermore, the magnetic powder and fibrous material are each treated with a coupling agent, and the particle surface is treated with a coating to remove attached moisture, so that conventional cracks and cracks caused by moisture gasification are eliminated. Occurrence is also prevented. In addition, treatment with a coupling agent improves the physical properties of the magnetic powder surface and fibrous material surface, making it possible to control the viscosity and plasticity of the binder, which improves processability and moldability, and improves mechanical properties. A magnet roll that is both magnetically and well-balanced can be obtained. In particular, when the entire roll shaft, including the roll shaft, is integrally molded, the amount of plastic magnet increases by the volume occupied by the conventional through shaft, which means that the magnetic force is stronger than before, and the dimensions of the magnet roll are increased. Improved accuracy and reduced weight are also beneficial.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a longitudinal sectional view and a transverse sectional view showing one embodiment of the invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the invention. (1) (11) - Plastic magnet roll, +21
(12) - Roll body, (3) - - Metal roll shaft, (13) (14) - Roll shaft.

Claims (1)

[Scope of Claims] 1. A plastic characterized by forming a plastic magnet made of a fibrous material surface-treated with a coupling agent, magnetic powder, and a synthetic resin binder around a roll shaft to form an integral structure. magnet roll. 2. The plastic magnet roll according to claim 1, wherein the roll shaft is a metal shaft. 3. The plastic magnet roll according to claim 1, wherein the roll shaft is made of the same material as the plastic magnet and integrally molded with the plastic magnet. 4. Any one of claims 1 to 3, wherein the coupling agent for treating the fibrous material is any one of a silane coupling agent, an aluminum coupling agent, a titanate coupling agent, and a zircoaluminate coupling agent. One of the listed plastic magnet rolls. 5. Any one of claims 1 to 4, wherein the coupling agent for treating the magnetic powder is any one of a silane coupling agent, an aluminum coupling agent, a titanate coupling agent, and a zircoaluminate coupling agent. The plastic magnet roll described in .