JPH06244022A - Magnet roll - Google Patents

Abstract

PURPOSE:To enhance rigidity by containing a specific amount of a polymer whose tensile elastic modulus exceeds a specific value in a polymer which forms a resin magnet. CONSTITUTION:A magnet roll used in a developing device or a cleaning device comprising a resin magnet formed of a polymer and magnetic powder contains 50wt.% and over high polymeric substance whose tensile elastic modulus exceeds 5X10<3>kg/cm<2>. Polyamide resin, hard polyvinyl chloride resin, polystyrene resin, polypropylene resin, styrene acrylonitrile resin ABS resin, polypropylene resin, polycarbonate resin or the like are cited as this high polymer. They are used individually or blended with the other polymers. This construction makes it possible to produce enough rigidity and prevent the generation of deflections or deformations. Furthermore, the application of this magnet roll makes it possible to reduce the whole weight as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet roll used in a developing device or a cleaning device such as an electronic copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, as a magnet roll used for such an application, one in which a cylindrical magnet body is integrally formed around a support shaft made of metal such as steel is generally used. As the magnet body used here, a molded product such as a sintered magnet, a resin magnet, or a magnetic alloy is mainly used. In such a magnet roll, a cylindrical sleeve made of a non-magnetic material such as aluminum is rotatably attached to a magnet roll supporting portion of a developing device such as a copying machine on the outer peripheral side of the supporting shaft, so that a toner It is designed to be used for transferring developer such as.

However, with conventional magnet rolls,
When the magnet body is made of a resin magnet, the rigidity is insufficient, and there is a problem that the magnet roll is bent or deformed. In addition, when the magnet body is made of a sintered magnet or a magnetic alloy, the weight of the entire magnet roll is inevitably heavy.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a magnet roll which has sufficient rigidity and can be reduced in weight.

[0005]

Therefore, in the present invention, in a magnet roll used in a developing device or a cleaning device comprising a resin magnet formed of a polymer and a magnetic powder, the polymer polymer is used. 50% by weight of high molecular weight polymer having a tensile elastic modulus of 5 × 10 ³ kg / cm ² or more
By including the above, the rigidity is improved and the weight is reduced.

[0006]

The magnet roll used in the present invention has a tensile elastic modulus of 5 × in the high molecular weight polymer forming the resin magnet.
By containing a high molecular weight polymer of 10 ³ kg / cm ² or more in an amount of 50% by weight or more, the rigidity becomes sufficient,
Bending and deformation can be prevented. In addition, it is possible to reduce the weight as a whole by using the resin magnet.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a magnet roll according to the present invention. Reference numeral 11 in the figure denotes the magnet roll according to the present invention. The magnet roll 11 is composed of a cylindrical roll portion 12 at the center and support portions 13 and 13 at both ends. Roll part 12 and supporting parts 13, 13
Are integrally formed by a resin magnet.

As this resin magnet, one obtained by kneading a high molecular polymer and magnetic powder such as ferrite or rare earth cobalt and molding and magnetizing it by using a magnetic field injection molding machine or the like is used. The blending ratio of the high molecular weight polymer and the magnetic powder is determined by the magnetic characteristics desired for the magnet roll 11, and usually the surface magnetic flux density is 700 gauss or more. Therefore, the magnetic powder should be blended in an amount of about 85 to 90 wt%. There are many.

As the above-mentioned high molecular weight polymer, a high molecular weight polymer having a tensile elastic modulus of 5 × 10 ³ kg / cm ² or more is used.
Those containing more than wt% are preferable. Tensile elastic modulus is 5 × 10
^If it is less than ³ kg / cm ^2, the rigidity of the support portions 13 and 13 and the roll portion 12, which will be described later, may be insufficient, which may cause inconvenience such as bending and deformation of the magnet roll 11.

Specific examples of the high molecular weight polymer having a tensile elastic modulus of 5 × 10 ³ kg / cm ² or more include polyamide resin (nylon), rigid polyvinyl chloride resin, polystyrene resin, polypropylene resin, styrene acrylonitrile resin, ABS resin, polyacetal resin, polycarbonate resin, polyphenylene resin, polysulfone resin and the like can be mentioned, and when these are used alone or blended with other polymers, they are used by blending so as to be 50% by weight or more.

The supporting portions 13 and 13 are formed by intersecting both end portions of the cylindrical roll portion 12 with the circumferential surface and being cut out in one plane parallel to the central axis of the roll portion 12. In this example, the circle is divided into two parts by a chord smaller than the diameter, and the cross-sectional shape is obtained by removing the inferior arc part.

In such a magnet roll 11, the tensile modulus of elasticity is 5 × in the high molecular polymer forming the resin magnet.
By containing a high molecular weight polymer of 10 ³ kg / cm ² or more in an amount of 50% by weight or more, the rigidity becomes sufficient,
Bending and deformation can be prevented. In addition, the support portion 13 formed by cutting out the end portion of the roll portion 12,
Since the number is 13, the developing unit of the copying machine can support the magnet roll 11 as it is by providing a receiving portion that matches the supporting portions 13 and 13. Moreover, since the magnet roll 11 can be molded by injection molding once, the manufacturing is easy, and the supporting portions 13 and 13 have a simple shape. Therefore, the structure of the molding die is also good. It becomes simple and the manufacturing cost can be reduced. Further, since the resin magnet is used and the support shaft is not necessary, the weight can be reduced as a whole.

FIGS. 2 and 3 show another example of the magnet roll of the present invention. In the magnet roll 11 of FIG. 2, the support portions 13 and 13 of the magnet roll 11 are notched at both ends by four planes. The cross-sectional shape is a quadrangle. Further, in the magnet roll 11 of FIG. 3, the metal support shaft has a quadrangular shape. In these examples as well, the same operational effects as those of the magnet roll of the above-described embodiment can be obtained. In addition, in both of the above embodiments, both ends of the roll portion 12 are cut out to form two support portions 13 and 1.
Although 3 is formed, it is of course possible to cut out only one end to form the support portion 13.

(Experimental Example) Nylon-6 resin, polypropylene resin, and high-density polyethylene resin were used as high molecular weight polymers, and 800 g of strontium ferrite powder (GP-330 manufactured by Toda Kogyo) was added to 100 g of each resin.
3 g of a lubricant was blended, kneaded at a high temperature with a kneader, and then pulverized with a pulverizer to obtain granules. Next, this granular material was injection-molded by a magnetic field injection molding machine and magnetized to obtain a magnet roll having a diameter of 17 mm and a length of 220 mm having the shape shown in FIG. The magnetic field of the injection molding machine was implemented with 4-pole polar anisotropy. The tensile elastic modulus of the resin used and the surface magnetic flux density of the obtained magnet roll are shown in Table 1 below.

[0015]

[Table 1]

Further, the obtained magnet rolls were high in rigidity and strength of the roll portion and the supporting portion, and were sufficiently durable for practical use.

[0017]

As described above, in the magnet roll of the present invention, 50% by weight or more of a polymer having a tensile elastic modulus of 5 × 10 ³ kg / cm ² or more is contained in the polymer forming the resin magnet. Since it contains, the rigidity is sufficient,
Bending and deformation can be prevented. In addition, it is possible to reduce the weight as a whole by using the resin magnet.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a magnet roll of the present invention.

FIG. 2 is a perspective view showing another example of the magnet roll of the present invention.

FIG. 3 is a perspective view showing another example of the magnet roll of the present invention.

[Explanation of symbols]

11 ... Magnet roll, 12 ... Roll part, 13 ...
Support section

Claims (1)

[Claims] 1. A magnet roll for use in a developing device or a cleaning device comprising a resin magnet formed of a high molecular polymer and magnetic powder, wherein the high molecular polymer has a tensile elastic modulus of 5 × 10 ³ kg / c
A magnet roll comprising 50% by weight or more of a high molecular weight polymer having a m ² or more.