JP4344193B2 - Magnetic seal member and manufacturing method thereof - Google Patents

Description

  The present invention relates to a magnetic seal member for preventing leakage of magnetic toner from a container for storing magnetic toner in an electrophotographic apparatus such as a copying machine or a laser beam printer, and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, in electrophotographic apparatuses such as copying machines and laser beam printers, seal members for preventing magnetic toner from flowing out of a developing region are provided at both ends of a developer carrier. As this seal member, a non-contact magnetic seal member using magnetic attraction is used. The magnetic seal member is formed by laminating a resin magnet for magnetically attracting magnetic toner and an iron yoke having a high magnetic permeability in order to prevent the magnetic lines of force of the resin magnet from diverging outside the developing carrier.

Japanese Patent Laid-Open No. 11-166626 introduces a technique for preventing the formation of burr in a magnet of a substantially semi-cylindrical magnetic seal member in which a resin magnet and a magnetic yoke produced by punching or the like are laminated.
JP-A-11-166626

  However, the conventional magnetic seal member can prevent the burr of the magnet from being formed. However, since the iron yoke produced by punching such as a press is inserted into the mold and molded, the parts to align the direction of the yoke Dedicated equipment such as a robot that inserts the feeder and yoke into the mold is required, which increases the cost of parts. In addition, it is extremely difficult to make the inner diameter of the mold and the yoke to be inserted completely the same, and a step is generated on the boundary surface between the layers, and the inner diameter tends to be uneven. Furthermore, when an anisotropic magnet is used as the resin magnet, a permanent magnet for orienting the magnetic powder is placed in the mold, so the yoke inserted before molding maintains its posture by magnetic attraction of the permanent magnet. The problem of being difficult to do, prone to production interruptions, and requiring special measures for that, has not been completely solved.

  Accordingly, the present invention has been made in view of the above-described problems, and an object thereof is to provide a magnetic seal member that is low in cost, has good dimensional accuracy, and is excellent in productivity.

  In order to solve the above-mentioned problems, the present inventor has intensively studied and, as a result, without using a yoke with high magnetic permeability, such as iron with high permeability even with a resin in which soft magnetic alloy powder is dispersed. Similarly, it was found that the divergence of the magnetic field lines of the resin magnet can be prevented.

  That is, the magnetic seal member according to the present invention is a magnetic seal member for electrophotography having a yoke portion and a magnet portion, and the magnet portion is composed of a resin magnet layer containing hard magnetic alloy powder and a resin binder, and the resin magnet A magnetic seal member characterized in that a layer containing a soft magnetic alloy powder and a resin binder is laminated on the layer as a yoke portion.

  The resin used for the magnet part and the resin used for the yoke part are preferably the same resin. The resin for forming the yoke part is preferably an amide resin.

  The method of manufacturing a magnetic seal member for electrophotography having a yoke portion and a magnet portion according to the present invention includes injecting a raw material composition containing a hard magnetic alloy powder and a resin binder into a mold, and a magnetic layer having a predetermined shape, Injecting a raw material composition containing a soft magnetic alloy powder and a resin binder to laminate and form a layer to be a yoke part; and magnetizing a predetermined part of the magnetic layer to obtain a resin magnet layer to be a magnet part It is characterized by having.

  As described above, according to the method for manufacturing a magnetic seal member of the present invention, it is possible to provide a magnetic seal member that is low in cost, good in dimensional accuracy, and excellent in productivity.

  As shown in FIG. 1, the magnetic seal member 1 according to the present invention has a similar shape that forms a magnetic circuit with the resin magnet 2 on one side of the resin magnet 2 as a resin-bonded magnet of the illustrated shape. It is obtained by joining a yoke 3 made of a resin in which soft magnetic alloy powder is dispersed by molding means, and has a part of an inward cylindrical surface 1a and a linear part 1b having an arc shape of about 120 ° to 240 °. It consists of. The magnetic seal member 1 has a width of 2 to 5 mm for the resin magnet 2 and 0.3 to 3 mm for the yoke. Furthermore, the radius range of the inner circumference of the arc in this embodiment is R5 to 15 mm.

As the magnetic powder used for the resin magnet 2, it is known to use rare earth element magnetic powder and ferrite magnetic powder. As the rare earth element magnetic powder, a hard magnetic alloy powder such as a rare earth element R ₁ —Co based magnetic powder, a rare earth element R ₂ —Fe—B based magnetic powder, or a rare earth element R ₃ —Fe—N based magnetic powder is used. Can do. Here, the rare earth elements R ₁ and R ₃ are composed of one or more rare earth elements including Sm, and the rare earth element R ₂ is composed of one or more rare earth elements including Nd.

Accordingly, the rare earth element R ₁ —Co based magnetic powder is Sm—Co based magnetic powder, and Sm—Co based powder in which a part of Sm is replaced with one or more of alloys composed of Nd, Pr, Y, Ce, and Dy. Magnetic powder, magnetic powder to which one or more of Zr, Hf and Ti are added in the Sm—Co—Cu—Fe system are included.

The rare earth element R ₂ —Fe—B based magnetic powder includes Nd—Fe—B based magnetic powder, Nd—Fe—B in which a part of Nd is substituted with one or more of Dy, Pr and Y alloys. One type or two or more types of alloys composed of Ga, Zr, Hf, Al, Cu, Mn, Ti, and Si are added in the system magnetic powder, Nd—Fe—B—Co system magnetic powder, and Nd—Fe—B—Co system. Magnetic powder made of plastic is included.

  These magnetic powders are obtained by forming a magnetic powder produced by a rapid solidification method by a hot isostatic pressing method (HIP method), then plastically processing the bulk of the hardened magnetic powder and then pulverizing it.

  Moreover, there is a magnetic powder produced by a hydrogen treatment method (HDDR method).

  On the other hand, as the ferrite magnetic powder, Sr-based and Ba-based ferrites are well known, and the manufacturing method is disclosed in Japanese Patent Application Laid-Open No. 2001-284112. These rare earth element magnetic powders and ferrite magnetic powders can be used singly or in combination of two or more.

  It can also be used as a granulated magnetic powder after the above magnetic powder is pulverized. Micronized particles are easy to move when applied with a magnetic field due to the small particles, and are easily oriented in the direction of the magnetic field.

  The thermoplastic resin as the binder is not particularly limited as long as it can be molded into a predetermined shape, and is appropriately selected according to the intended use of the resin magnet. Polyamide such as 12 nylon, 6 nylon, 6, 6 nylon, polyphenylene sulfide (PPS), polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. Examples thereof include thermoplastic resins such as polyester, polycarbonate, polyetherketone, polyetherimide, and polyacetal, and one or more of these may be used in combination. Of these, polyamide and polyphenylene sulfide are particularly preferably used from the viewpoints of moldability, affinity with magnetic powder, mechanical properties, price, and the like.

  The magnetic powder can be subjected to an appropriate surface treatment as required. For example, the magnetic powder can be subjected to a coupling treatment in advance and mixed with the resin raw material. In this case, a silane or titanate coupling agent can be used as the coupling agent. In addition, conventionally used plasticizers, stabilizers, lubricants, reinforcing agents and the like are also appropriately used depending on the purpose.

  The average particle size of the magnetic powder is preferably 0.5 to 500 μm, particularly preferably 10 to 100 μm. If the particle size of the magnetic powder is too small, mixing with the resin binder becomes difficult and the uniformity of the magnetic powder is extremely high. On the other hand, if the particle size of the magnetic powder is too large, it may be difficult to obtain a resin magnet or yoke having good magnetic properties.

  Examples of the soft magnetic alloy powder of the yoke include Fe-Si-Al alloy powder, Fe-Si alloy powder, Ni-Fe alloy powder, Fe-Co alloy powder, iron powder, and soft ferrite powder. Or two or more types are used in combination.

  The soft magnetic alloy powder of the yoke may have a maximum relative permeability of 1200 or more and 2000000 or less. Soft magnetic alloy powder can be obtained by melting the raw material by high frequency melting or the like to produce an ingot, and then using a crusher such as a jaw crusher, ball mill, or vibration mill to obtain a desired particle size or directly from the molten metal. It is known to obtain an alloy powder by a gas atomization method, a water atomization method, or the like. As another method, a roll rapid cooling method, that is, a molten metal is naturally dropped from a nozzle onto the peripheral surface of a high-speed rotating cooling roll and rapidly cooled and solidified on the peripheral surface to obtain a flaky powder, which is pulverized. There are methods for producing powders. For details, refer to Japanese Patent Publication No. 2003-64455, Japanese Patent Publication No. 2002-80945, Japanese Patent Publication No. 2000-290758, Japanese Patent Laid-Open No. 2002-206151, and the like.

  The optimum combination of these resin, hard magnetic alloy powder, and soft magnetic alloy powder can be appropriately selected according to the magnetic seal characteristics required for the electrophotographic apparatus.

  As a molding means for integrating the magnet portion and the yoke portion, a two-color molding method using a core back method or a core rotation method is preferably used. In addition, since the molding means forms the magnet part and the yoke part in the same mold, the step on the laminated boundary surface is small and good dimensional accuracy can be obtained.

  FIG. 4 is a diagram showing an outline of the two-color molding method. The distance between the upper mold and the lower mold of the mold 5 is adjusted to the width of the resin magnet 2 (3 mm in this example), and the hard magnet that becomes a magnet part in the mold is shown. A resin binder in which alloy powder is dispersed is injected from the injection port 6 to form a layer that becomes the resin magnet 2.

  As a method of magnetizing the resin magnet 2, in the case of an isotropic magnet such as Nd—Fe—B, a magnetic field is applied by a magnetic field generator after molding. On the other hand, in the case of an anisotropic magnet such as ferrite, since it is necessary to orient the magnetic particles during molding, a magnetic field is applied by a permanent magnet or the like disposed in the mold.

  Next, the mold is moved so as to provide a gap between the upper mold of the mold and the surface of the resin magnet 2 (1.5 mm in this example), and a resin binder in which soft magnetic alloy powder is dispersed is injected from the injection port 7 and resin is injected. A magnetic seal member 1 is manufactured in which a yoke made of a resin in which a soft magnetic alloy powder is dispersed in a magnet 2 is laminated.

  In this example, since a thermoplastic resin was used, a raw material containing at least a soft magnetic alloy powder and a resin binder was heated to 260 ° C. and injected. Since it is a thermoplastic resin, it hardens when the temperature drops after injection. On the other hand, when a thermosetting resin is used, it is necessary to apply heat to cure the resin.

  The resin in which the hard magnetic alloy powder is dispersed and the resin in which the soft magnetic alloy powder is dispersed may be cured immediately after the injection, or if the laminated form is maintained in an uncured state. Each resin may be cured after being laminated.

  It is explained that the resin binder in which the hard magnetic alloy powder serving as the magnet part is dispersed in the mold is injected first, and the resin binder in which the soft magnetic alloy powder is dispersed is injected later. The resin binder in which the alloy powder is dispersed is injected first, and after the yoke layer is formed, the resin binder in which the soft magnetic alloy powder is dispersed is injected, and after lamination, the magnetic field is applied to laminate the resin magnet 2 and the yoke. A magnetic sealing material can also be manufactured.

  The resin binder used for the yoke is not particularly shown, but any resin binder used for the resin magnet can be used without any particular problem.

  When inserting a conventional iron yoke, it is difficult to maintain the posture in the mold due to the influence of magnetic attraction of the permanent magnet, but the yoke 3 of the present embodiment is formed by molding means, That problem never happens.

  Further, since the molding is performed in the same mold, the step on the laminated boundary surface between the magnetic seal member 1 and the resin magnet 2 is 5 μm or less, which is 25 μm of the magnetic seal member in which a conventional iron yoke is inserted and molded. Compared to 1/5, it was improved.

  Further, since it is not necessary to manufacture an iron yoke and insert it into a mold as in the prior art, the structure of the manufacturing apparatus is simple because the iron yoke is manufactured and a robot part to be inserted into the mold is not required.

  As shown in FIG. 2, the magnetic seal member 1 of the present embodiment has a plurality of magnetic poles NS alternately magnetized in the radial direction of the inner peripheral surface, and the magnetic force in the normal direction on the surface of the development carrier is 100 to 100 at maximum. It is about 250 mT. However, the magnetic force pattern is appropriately set according to the developing mechanism, and is not limited to this, and it is possible to magnetize the linear portion or the outer peripheral surface according to the sealing property.

  As shown in FIG. 3, the magnetic field lines emanating from the resin magnet 2 are concentrated on the yoke 3, and the magnetic force on the yoke is not particularly limited, but it is usually required to be 30 mT or less. Such convergence of magnetic force can be achieved by a resin in which soft magnetic alloy powder such as Fe-Si-Al alloy powder is dispersed.

  From a resin magnet composed of 92% by mass of Nd—Fe—B alloy powder having a particle size of 10 μm to 200 μm and 8% by mass of 12 nylon, 90% by mass of Fe—Si—Al alloy powder having a particle size of 1 μm to 50 μm, and 10% by mass of 12 nylon. A magnetic seal member having a resin magnet width of 3 mm, a yoke width of 1 mm, and an arc radius of R8.5 mm was manufactured by a core back type two-color molding method. In addition, the number of magnetic poles was 6 in alternating NS in the radial direction.

  In the case of an isotropic magnet such as an Nd—Fe—B alloy powder, a magnetic field is applied after forming the hard magnetic powder. On the other hand, in the case of an anisotropic magnet such as ferrite, a magnetic field may be applied during molding.

  The resin in which the magnetic powder is dispersed is required to have a low permeability of a substance that causes oxidation of the magnetic material. When the permeability of such a substance is high, the surface of the magnetic material is oxidized, and in the case of a resin magnet, the magnetic force is reduced. In the case of a yoke, the magnetic permeability decreases and magnetic flux leakage occurs.

  The resin binder used by the magnet and the yoke is preferably the same. By using the same resin binder, it is not necessary to change the temperature of the mold, and the resin magnet and the yoke are not peeled off. Although the resin used for the magnet and the yoke can be changed, in this case, it is preferable to combine resins that can be molded at the same mold temperature.

  In this example, Fe-Si-Al alloy powder was used as the soft magnetic alloy powder. However, if the soft magnetic alloy is used, the material / composition ratio is not a problem, and the relative magnetic permeability is 1200 to 200,000. There is no particular problem.

  When the yoke is formed of resin, if the soft magnetic alloy powder is 96% by mass or less, the soft magnetic alloy powder is uniformly mixed with the resin binder. The lower limit is appropriately set according to the strength of the magnetic force of the magnet layer and the standard for leakage of magnetic flux.

  Although the present embodiment has been described using a thermoplastic resin, a thermosetting resin may be used.

  When the magnetic force of the magnetic seal member was measured, the maximum magnetic force in the normal direction of the resin magnet portion on the surface R8.0 of the developing carrier was 156 mT, and the magnetic force on the yoke was 12 mT. (Tesrameter GX-100 Nippon Electromagnetic Sokki Co., Ltd.) This magnetic characteristic is equivalent to that of a magnetic seal member in which a conventional iron yoke is inserted and molded. Further, the step at the laminated boundary surface between the resin magnet and the yoke was 5 μm or less, which was reduced to about 1/5 compared with 25 μm of the magnetic seal member in which the conventional iron yoke was insert-molded.

  Therefore, it was confirmed that the above-described manufacturing method can provide a magnetic seal member that satisfies the magnetic characteristics required for the electrophotographic apparatus and has good dimensional accuracy.

It is a perspective view which shows the magnetic seal member which concerns on an Example. It is a side view which shows the magnetic force pattern of the magnetic seal member which concerns on an Example. It is AA sectional drawing of FIG. 2 which shows the magnetic force line of the magnetic seal member based on an Example. It is a figure which shows the outline of a 2 color shaping | molding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic seal member 1a Cylindrical surface part 1b Linear part 2 Resin magnet 3 Yoke 4 Magnetic field line 5 Die 6, 7 Inlet

Claims (5)

A magnetic seal member for electrophotography having a yoke portion and the magnet portion,
The magnet part is composed of a resin magnet layer containing a hard magnetic alloy powder and a resin binder, and a layer containing a soft magnetic alloy powder and a resin binder is laminated on the resin magnet layer as the yoke part ,
A magnetic seal member , wherein a step of a laminated boundary surface between the magnet portion and the yoke portion is 5 μm or less . Magnetic seal member according to claim 1, wherein the resin used in the magnet part, and the resin used in the yoke portion, that but the same resin.   The magnetic seal member according to claim 1, wherein the resin for forming the yoke portion is polyamide or polyphenylene sulfide. A method of manufacturing a magnetic seal member for electrophotography having a yoke portion and the magnet portion,
Injecting a raw material composition containing a hard magnetic alloy powder and a resin binder into a mold to form a magnetic layer having a predetermined shape, and injecting a raw material composition containing a soft magnetic alloy powder and a resin binder into the mold Forming a layer to be the yoke portion, and laminating the magnetic layer and the layer to be the yoke portion ,
And a step of magnetizing a predetermined portion of the magnetic layer to obtain a resin magnet layer to be a magnet portion. The method for manufacturing a magnetic seal member according to claim 4, wherein the resin used for the magnet portion and the resin used for the yoke portion are the same resin.

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