JPS61181108A - Composite resin magnet roll composition - Google Patents

Abstract

PURPOSE:To obtain a composite resin magnet roll having high productivity which assures high magnetic force and orientation integration with a shaft by simultaneously using polyamide resin having a melting viscosity of a particular value or less and wax, aliphatic metal salt. CONSTITUTION:A composite resin magnet roll composition 2 using polyamide resin having melting viscosity of 50 poise or less at 200 deg.C has a very low viscos ity at a plastic condition and easily allows the axis for easy magnetization 4 of ferrite to be oriented very easily in the direction in line of magnetic flux against the oriented magnetic field. Therefore, a resin magnet roll 3 having a high magnetic force can be obtained. In this case, a magnet roll having melt ing viscosity of 50 poise or more has a larger resistance of viscosity and also has bad magnetic characteristic because orientation is interferred. Desirable amount of ferrite contained is 80-92wt% for total weight. If it exceeds 92wt%, kneading and molding become difficult and moreover deterioration of magnetic characteristic can also be detected. If it is under 80wt%, orientation of ferrite becomes higher for the oriented magnetic characteristic but magnetic characteris tic is lowered because amount is insufficient.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a composite resin magnet roll composition used in PPC copying machines, electrophotographic developing devices such as facsimile machines, and cleaning devices.

Conventional technology These magnetic rolls were constructed using rod-shaped or cylindrical sintered ferrite, but in recent years, nylon (
6, 66, 11, 12, etc.) It is constructed using a composite resin magnet material using a thermoplastic resin such as polypropylene, polyethylene, chlorinated polyethylene, or vinyl acetate as a binder. Resin magnet rolls have conventionally been produced by a method in which the axis of easy magnetization of shipherite is oriented in a certain direction by mechanical means, and by a method in which it is oriented by the action of a magnetic field. In the former method, as shown in FIG. 1a, a resin magnet material 2 is rolled with a rolling row 21 or the like to form a sheet-like magnet 3 in which the axis of easy magnetization 4 of ferrite is oriented in a direction perpendicular to the sheet surface. As shown in Figure 1, it is wound around the shaft 5 in the form of a roll and magnetized to form a magnet roll. By the way, as shown in FIG. 1C, in order to increase the orientation efficiency, several sheet-shaped magnets 3 are stacked and pressure-formed into a fan shape, and the separated pieces are pasted together adjacently around the shaft 5 to form a roll shape. Efforts have been made to use magnetism to create a magnetic roll.

(Figure 1d). The latter is called magnetic injection molding.
During injection molding, a strong magnetic field is applied to the plasticized composite resin magnet material in the mold to orient the axis of easy magnetization of the ferrite in the direction of the magnetic flux lines, forming a magnet roll.

In such conventional resin magnet rolls, in the former winding method, the easy magnetization axis 4 of the ferrite is oriented radially from the shaft, as shown in Figure 1, so the lines of magnetic flux are aligned with the magnetic poles on the circumference. High magnetic force cannot be obtained because it is not concentrated. On the other hand, in the method of pressure forming into a fan shape, a high magnetic force can be obtained because the axis of easy magnetization 4 of the ferrite is oriented in the direction of the magnetic flux lines, but the process is complicated and productivity is poor.

In the latter case, magnetic field injection molding, as shown in FIG. The axis of easy magnetization 4 of is oriented in the direction of the magnetic flux lines.

Because these lines of magnetic flux are concentrated in the direction of the magnetic poles due to the nature of the electromagnet, the orientation is efficient and a magnet with high magnetic force can be obtained, and the process is simplified and productivity is excellent.

Problems to be Solved by the Invention However, magnetic field injection molding is limited in the resin material used as the binder for the composite resin magnet material. The plastic magnet material in the injection molding holding mold is easily oriented in the direction of the magnetic flux lines by the oriented magnetic field, which allows the easy axis of magnetization of the ferrite particles in the resin magnet material to overcome the melt viscous resistance of the resin magnet material. The viscosity must be low enough to

Currently, nylon (6, 66, 11, 12, etc.) is used, but its viscosity is low enough for injection molding, and its magnetic properties are therefore limited because it is not sufficiently oriented. This is not limited to magnetic field injection molding, but when molding and magnetic field orientation are performed in separate processes, after obtaining a white roll-shaped molded product by injection molding, it is heated again and the orientation is performed in a magnetic field orientation mold. This is particularly important when the magnetic field is aligned.The present invention provides a composite resin magnet roll composition that can obtain high magnetic force in these magnetic field orientations.

Means for Solving the Problems The present invention provides 200
A composite resin magnet composition comprising a polyamide resin having a melt viscosity of 60 voids or less at °C, ferromagnetic ferrite powder, wax and a fatty acid metal salt, wherein the ferrite powder is in a proportion of 80 to 92% by weight based on the total amount. This is a composite resin magnet roll composition containing.

action The effects of the composition are as follows.

That is, the composite resin magnet roll composition of the present invention differs from conventional resin magnet roll compositions for injection molding in that it has an extremely low viscosity in the plastic state, and the axis of easy magnetization of the ferrite is aligned with the magnetic flux lines with respect to the orienting magnetic field. Since it is extremely easily oriented in the direction, a resin magnet roll with high magnetic force can be obtained. The reason for this is that the polyamide resin used in the present invention has a low melt viscosity of 60 voids or less at 200°C. In this case, if the melt viscosity at 200° C. exceeds 60 voids, the viscous resistance becomes large, the orientation becomes rough, and the magnetic properties deteriorate. The ferrite content is preferably 80 to 92% by weight based on the total amount, and if it exceeds 92% by weight, crosstalk, difficulty in molding, and deterioration of magnetic properties are observed.

This occurs because the ferrite powder is filled to an extremely high degree and cannot respond to the applied magnetic field. If the content is less than 80% by weight, the orientation of the ferrite will be high with respect to the applied orientation magnetic field, but the amount will be insufficient and the magnetic properties will deteriorate.

As the ferromagnetic ferrite powder, commercially available ferrites such as barium ferrite and strontium ferrite can be used. The polyamide resin used in the present invention has strong adhesive properties and has extremely poor release from the mold during molding, so it is necessary to give sufficient consideration to release.

Mold releasability during molding can be improved by containing wax, but since wax alone significantly increases the melt viscosity of the composition and reduces the magnetic properties, when a fatty acid metal salt is used in combination, the synergistic effect will prevent the magnetic properties from decreasing. A mold release effect can be expected.

No mold release effect is observed when the fatty acid metal salt is contained alone. As the wax, polyethylene wax, polypropylene wax, ester wax, or amide wax can be used, and as the fatty acid metal salt, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, calcium laurate, etc. can be used.

Example The present invention will be explained by way of examples.

Examples 1 to 6: 160 to 180 of each composition shown in Table 1
Mixing is performed using a pressure kneader heated to ℃. After kneading, the mixture is cooled and pulverized into 2 to 5 mm pieces using a pulverizer. Put it into an injection molding machine and mold it together with the shaft, φ=20 J=20
0 roll-shaped molded product is obtained.

This is heated in a heating furnace whose temperature is controlled to 200° C., inserted into an orientation mold, immediately applied with an orientation magnetic field, and taken out after cooling. The applied magnetic field strength is 10,0000 on the magnet roll surface.
It is e.

After the resin magnet roll was taken out and sufficiently cooled, the surface magnetic flux density was measured using a Gauss meter. The measurement was carried out by bringing a Gaxmeter Hall element into contact with the surface of the magnet roll. The results are shown in Table 2.

Comparative Examples 1 to 6: Magnet rolls were prepared in the same manner as in the Examples using each of the compositions shown in Table 3, and the surface magnetic flux densities thereof were measured. Table 4 shows the results.

However, in Comparative Example 6, the temperature was controlled at 250°C, which is higher than the melting point of nylon.

Table 1 Polyamide A; Melt viscosity 47 voids (200"C) Polyamide B; y32r (I) Polyamide C; / 5z (z) Polyamide D; #80 # (220°C) a
) Ferrite manufactured by Toda Kogyo ■ b) Manufactured by Sakai Chemical Industry ■ C) d) Manufactured by Lion Akzo ■ e) Manufactured by Mikata Petrochemical ■ 1) Manufactured by Toshi ■ Table 2 Evaluation ○; Table 4 Rating: O; Good mold release property ×; Bad mold release property Effects of the invention As described above, according to the present invention, by using together a polyamide resin having a melt viscosity of 50 voids or less at 200°C, a wax, and a fatty acid metal salt. It is possible to manufacture a highly productive composite resin magnet roll that has high magnetic force due to magnetic field orientation, which could not be achieved with conventional resin magnet rolls, and can be oriented integrally with the shaft.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of magnetic field orientation, and FIG. 2 is an explanatory diagram of a conventional mechanical orientation method. 1... Rolling roll, 2... Ferrite particles, 3... Sheet magnet, 4...
...Easy magnetization axis, 6...Shaft. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
-Ippatsuso J-le

Claims (2)

[Claims] (1) A composite resin magnet roll composition containing a polyamide resin having a melt viscosity of 50 poise or less at 200°C, ferromagnetic ferrite powder, wax, and a fatty acid metal salt. (2) Ferromagnetic ferrite powder is 80 to 92% of the total amount
The composite resin magnet roll composition according to claim 1, wherein the composite resin magnet roll composition is contained in a proportion of % by weight.