JP2000192104A - Manufacture of magnet molding, and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a magnet molding and its manufacturing device in which a high surface magnetism can be obtained, an orientation die can be miniaturized and an electromagnet as one example of a magnetic pole can be miniaturized, and the required current to be applied can be small. SOLUTION: In a manufacturing method of a magnet molding to obtain the magnet molding such as a magnetic piece 4 by extruding a molten mixture of magnetic powder and resin binder into the magnetic field, an extrusion mouthpiece is formed, and disposed in magnetic poles 3A, 3B, the molten mixture 11 is extruded at the position to obtain the high surface magnetism in a product cavity 8 through an orientation die 2 in which a concentrated part 5B of a magnetic metal 5 is disposed adjacent to only a part in the vicinity of an outlet part on the concentration magnetic pole 3A side. A concentrated part 5B of the magnetic metal 5 on the concentration magnetic pole 3A side need not be provided over the whole length of the orientation die 2, and a magnetic pole piece as one example of the magnetic pole 3 to be used in forming the magnetic field can be miniaturized, and the multiple functions such as the contraction, high magnetization, orientation, and shape stabilization, can be satisfied even when the applied current is small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnet molded product such as a magnetic piece by extruding a molten mixture of a highly versatile magnetic powder such as ferrite and a resin binder into a magnetic field. And its device.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, an electrostatic recording apparatus, or the like, a developing roller for visualizing an electrostatic latent image on a latent image holder such as a photosensitive drum is provided inside a rotating sleeve. A magnet roller formed of a resin magnet or a rubber magnet is disposed on the surface of the sleeve, and a magnetic developer (toner) carried on the surface of the sleeve is jumped onto the latent image holding member by a magnetic force characteristic of the magnet roller. Supplying toner to the surface of the image carrier,
A developing method for visualizing an electrostatic latent image is known. Conventionally,
The magnet roller is a pellet-shaped resin magnet composition or rubber magnet composition in which a magnetic powder such as ferrite is mixed with a thermoplastic resin such as nylon or polypropylene or a binder of rubber, using a mold around which a magnetic field is formed. It is manufactured by injection molding or extrusion molding to form a roller and magnetize it to desired magnetic properties.

However, with the recent development of electrophotographic apparatuses and the like, there is a tendency that a more complicated magnetic force pattern is required for the magnet roller, but the magnetic force pattern that can be designed with the conventional magnet roller is limited. Yes, we cannot fully meet this demand. Therefore, conventionally, in order to increase the degree of freedom of the magnetic force pattern of the magnet roller, a plurality of magnetic pieces magnetized with magnetic poles corresponding to the target magnetic force pattern are formed with the resin magnet or the rubber magnet, and these are formed on the shaft. 2. Description of the Related Art A desired magnetic force pattern is formed by pasting around a periphery. In such a magnetic piece, it is technically difficult to obtain a high magnetic force piece having a surface magnetic force of 1050 gauss or more by extrusion in a magnetic field, and it is generally manufactured by injection molding in a magnetic field. In particular, when a magnetic roller is formed by joining a plurality of magnetic pieces, it is more difficult because the constituent pieces are relatively thin. Furthermore, under the situation where today's printers, copiers and the like have to cope with miniaturization and high performance, the appearance of small high magnetic pieces having a surface magnetic force of 1050 gauss or more is expected.

Under such circumstances, Japanese Patent Application Laid-Open No. 6-99520 has proposed a method for realizing magnetic field extrusion molding which is more economical and workable than magnetic field injection molding. By reducing the temperature difference in the radial direction of the molten resin magnet material passing through the molding space (product cavity) in the extrusion die, the flow velocity difference in each part is reduced, and no shrinkage voids or cracks are generated. An object of the present invention is to obtain a very anisotropically oriented resin magnetic roller having high surface smoothness and excellent shape and dimensional accuracy while maintaining the uniformity of the surface magnetic force. Further, the method disclosed in Japanese Patent Application Laid-Open No. Hei 5-21252 discloses that the magnetic particles rotate due to the shearing force caused by the velocity gradient generated between the center of the flow and the wall surface of the die in the die cavity. It is an invention aimed at preventing the orientation from being disturbed, and proposes to use a die having a structure in which a part or the whole of a land cross section extends in the extrusion direction.

[0005]

However, in the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-99520, a hollow cylindrical magnetic roller is directly manufactured at once by an extrusion die. A high concentrated magnetic field cannot produce a high surface magnetic force at a specific point, which is disadvantageous. For this reason, in order to make it possible to form a high surface magnetic force at a specific point portion by a localized concentrated magnetic field, a magnetic piece is formed by an extrusion die, and the plurality of magnetic pieces are formed around an axis. Research has been conducted on joining to form a magnetic roller. Further, in Japanese Unexamined Patent Publication No. Hei 5-21252, a sufficient solution has not yet been found for the disorder of the orientation, and the interaction with the wall surface is caused by a slight dimensional change at the time of extrusion. This caused problems such as disordered orientation and lack of dimensional stability.

Generally, to obtain a high surface magnetic force, it is necessary to orient magnetic powder such as ferrite in a form suitable for the purpose. For this purpose, the magnetic force is concentrated around an oriented die as an extrusion die. The concentrated magnetic pole to be set and the opposing magnetic pole opposite to this are installed, and the molten resin magnet material that is extruded through the orientation die by the strong magnetic force from these opposing magnetic poles toward the concentrated magnetic pole is magnetized and locally applied to the magnetic piece as a product. With a concentrated magnetic field, a high surface magnetic force can be formed at a specific point. However, the orientation die as a die used for extrusion in a magnetic field as described above,
Since it is necessary to satisfy various functions such as aperture, high magnetization, orientation, shape stabilization, etc., the size becomes large, the size of the magnetic piece used as a magnetic pole for forming a magnetic field becomes large, and therefore, the applied current also needs a large current.

Accordingly, the present invention solves the above-mentioned problems in the conventional method of manufacturing a magnet molded product, and achieves a high surface magnetic force while reducing the size of the alignment die and reducing the magnetic pole size.
An object of the present invention is to provide a method and an apparatus for manufacturing a magnet molded product that can reduce the size of an example of an electromagnet and require a small applied current.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention provides a method of manufacturing a magnet molded product by extruding a molten mixture of a magnetic powder and a resin binder into a magnetic field to obtain a magnet molded product. The molten mixture is extruded through an orientation die in which a magnetic metal for orienting the magnetic powder is arranged on a concentrated magnetic pole side in a magnetic pole constituting a die for extrusion molding. Further, the present invention provides a magnet molded product manufacturing apparatus for obtaining a magnet molded product by extruding a molten mixture of a magnetic powder and a resin binder into a magnetic field, wherein a magnetic metal for orienting the magnetic powder at an outlet of a product cavity is provided. The molten mixture is extruded through an orientation die disposed on a concentrated magnetic pole side in a magnetic pole constituting a die for extrusion molding. Further, in the present invention, in the method and the apparatus for manufacturing a magnet molded product, a distance between the magnetic metal and an outlet of a product cavity is 10 mm or less. Further, the present invention provides the method and the apparatus for manufacturing a magnet molded product, wherein the length of the magnetic metal in the extrusion direction is 1/3 to 1/50 of the length of the orientation die. is there. Further, the present invention provides a method and an apparatus for manufacturing a magnet molded product, wherein the magnet molded product is a magnetic piece for a magnetic roller, and these are used as means for solving the problems. is there.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view of a method and an apparatus for manufacturing a magnet molded product of the present invention.
FIG. 1B is a side sectional view and an outlet side front view of an orientation die, FIG. 2 is a side sectional view and a front view of a magnetic roller as a product, and FIG. FIG. 3 is an explanatory diagram of magnetization. As shown in FIG. 1 which is an embodiment of the present invention, a method of manufacturing a magnet molded product such as a magnetic piece 4 or the like by extruding a molten mixture 11 of a magnetic powder and a resin binder into a magnetic field. In the above, an orientation die is provided which is arranged in the magnetic poles 3A and 3B by forming a die for extrusion molding, and a concentrated portion 5B of the magnetic metal 5 for orienting the magnetic powder in the molten mixture is arranged at an outlet of the product cavity 8. 2, wherein the molten mixture 11 is extruded. The concentrating unit 5
As shown in FIG. 1B, the position B is disposed near the outlet, and the distance L1 from the outlet is not particularly limited, but is preferably 10 mm or less. Further, the total length L2 of the alignment die is not particularly limited.
It is preferably about 150 mm. The length of the magnetic metal concentrating portion 5B in the extrusion direction is one of the length of the alignment die.
/ 3 to 1/50 (about 3 mm) is preferred. Concentration unit 5B
The width W is determined in reverse from the magnetic force pattern required for the magnetic roller, and is not an essential component of the present invention.

As shown in FIG. 1 (A), a molten mixture 11 of a magnetic powder and a resin binder, which passes through an orientation die 2 as a die for extrusion molding to become a magnetic piece 4 as a product, is placed in a melting cylinder 1. After flowing down, a magnetic pole 3 as a magnetic field generating device for alignment is disposed, for example, above and below the alignment die 2 so as to be extruded in a magnetic field. The concentrated magnetic pole 3A is located above, and the opposing magnetic pole 3B is located below.
Fig. 3 shows the concentrated magnetic field lines from
A high surface magnetic force is obtained at the position P as shown in FIG. At this time, generally, in order to obtain a high surface magnetic force, a high concentrated magnetic force line from the opposed magnetic pole 3B to the concentrated magnetic pole 3A is required. For this purpose, the orientation die 2 as a die used for extrusion molding in a magnetic field is required. The aperture, high magnetization, orientation, and the need to satisfy multiple functions such as stabilization of the shape are large, and the size of the magnetic piece, which is an example of the magnetic pole used for forming the magnetic field, is large. The present invention
As shown in FIG. 1B, a concentrated magnetic pole 3 of an orientation die 2 arranged in magnetic poles 3A and 3B by forming a die for extrusion molding.
The narrow concentrated portion 5B of the magnetic metal 5 is disposed adjacent to the position (corresponding to the position P in FIG. 3B) where a high surface magnetic force is to be obtained in the product cavity 8 only in the vicinity of the exit portion on the A side. However, this is based on the finding that the molten mixture 11 sufficiently satisfies various functions such as high magnetic force, orientation, and shape stabilization. In addition,
As for the orientation, a magnetic metal tip for forming a magnetic field is provided at the outlet, and the main part of the piece magnetization is used, so shearing due to the velocity gradient generated between the flow center and the die wall in the conventional die cavity. Rotation of the magnetic particles, that is, disturbance of the orientation due to the force can be prevented, and high magnetic force can be achieved. In addition, regarding the stabilization of the shape, the raw material composition used for producing the magnetic piece contains a very high proportion of magnetic powder and differs from the general extruded material in flow characteristics.
Reflecting this, it is common sense that not only is the land at the tip of the base required for stabilization of the shape unnecessary, but also
In the production of high magnetic force magnetic rollers, it is rather harmful as described above.

As shown in FIG. 1B, the alignment die 2 has a predetermined length, and a product cavity 8 defined by a magnetic metal upper die 5 and a magnetic metal lower die 6 has a magnetic metal lower die. 6. Left and right non-magnetic metals 7A and 7B are disposed between the magnetic metal upper mold 5 and the product cavity 8, and the magnetic metal concentrated portion 5B is adjacent to a position where a high surface magnetic force is to be obtained in the product cavity 8. The nonmagnetic metals 7A and 7B are divided at this portion so as to be arranged. In the present invention, the concentrated portion 5B of the magnetic metal is provided only in the vicinity of the outlet portion, and high magnetic force lines from the lower magnetic metal die 6 to the upper magnetic metal die 5 only through the concentrated portion 5B,
A higher surface magnetic force is obtained by concentrating the magnetic force more.

Although the cross-sectional shape of the product cavity 8 in the alignment die 2 shown in FIG. 1B is substantially rectangular, in actuality, as shown in FIGS. 4 is a plurality of magnetic drum pieces 4A
(N pole), 4B (S pole), 4C (N pole) and 4D (S pole)
The poles are joined around a shaft 9 to form a magnetic roller 10, and thus the cross-sectional shape of the magnetic piece 4, that is, the product cavity 8, forms a sector shape. Although the magnetic piece as an example of the magnet molded product has been described here, a cylindrical magnetic body can be formed. Further, as for the melting cylinder 1 in which the molten mixture 11 of the magnetic powder and the resin binder is melted and flows down to the alignment die 2, the molten mixture 11 fed by the extruder (not shown) flows in the flowing direction of the melting cylinder 1. Is maintained at an appropriate temperature (around 120 °) in a heat insulation zone divided into several parts (cooled, etc.), flows down at an appropriate flow rate, and has a lubricating material on the way, for example, the molten mixture 11 at a molding temperature. A thermoplastic resin such as an olefin-based resin having high fluidity or a polyolefin-based wax may be mixed and sent to the alignment die 2.

The composition for resin magnetism, which is the molten mixture 11, is obtained by mixing and dispersing magnetic powder and the like in a resin binder. As the binder resin, a resin generally used as a binder for a resin magnet can be used. Specifically, polyamide resin, polypropylene, polyethylene, polystyrene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT),
Various thermoplastic resins such as polyphenylene sulfide (PPS), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate (EEA), ethylene-vinyl alcohol copolymer (EVOH) alone or
These can be used in combination.

As the magnetic powder mixed and dispersed in the resin binder, known magnetic powders conventionally used in compositions for resin magnets of a magnetic roller can be used. , Ba ferrite and other ferrite magnetic powders, Sm-Co alloys, Nd-Fe-
B-alloys, Ce-Co alloys and other magnetic earth-based alloy powders can be exemplified. This magnetic powder can be subjected to a known pretreatment as necessary. For example, a pretreatment using a coupling agent can be performed and used in the present invention. In particular, in the present invention, it is preferable to perform a coupling treatment using a silane coupling agent or a titanate coupling agent. By using a magnetic powder subjected to a proper coupling treatment, the melt fluidity at the time of high filling can be more effectively improved.

As the silane coupling agent, γ-
Aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ
-Aminopropyltrimethoxysilane, ureidopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane And γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane Etc. are particularly preferably used.

Examples of the titanate-based coupling agent include isopropyl bis (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, isopropyl triisostearoyl titanate, and diisopropyl bis (dioctyl pyrophosphate) titanate. , Tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate,
Bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate)
Ethylene titanate and the like are exemplified, and among them, isopropyl bis (dioctyl pyrophosphate) titanate is particularly preferably used.

The magnetic powder used in the present invention is not particularly limited. However, from the viewpoint of the melt fluidity of the obtained composition for resin magnet, the orientation of the magnetic powder, the filling ratio, and the like, the average particle diameter is 0%. It is preferably from 0.5 to 100 μm, particularly preferably from 0.7 to 20 μm. In the composition for a resin magnet of the present invention,
In addition to the resin binder component, a compound having a magnetic powder and a hindered phenol resin, a filler having a large reinforcing effect such as mica, whisker or talc, carbon fiber, or glass fiber does not disturb the spirit of the present invention. It can be appropriately added within the range. That is, the magnetic force required for the molded product is relatively low, and when the filling amount of the magnetic powder is small, the rigidity of the molded product tends to be low. In that case, mica, whisker, etc. A filler can be added to reinforce the molded article. As the filler suitably used in the present invention, mica or whiskers are preferable. As the whiskers, non-oxidized whiskers made of silicon carbide and silicon nitride, ZnO, MgO, Ti
Metal oxide whiskers composed of O ₂ , SnO ₂ , Al ₂ O _{3 and the} like, and double oxide whiskers composed of potassium titanate, aluminum borate, basic magnesium sulfate and the like, among them, among these, A double oxide whisker is particularly preferably used because it can be easily combined with plastic. When these fillers are used, the mixing ratio is not particularly limited, but is usually about 2 to 30% by weight, particularly about 5 to 20% by weight of the whole composition for resin magnets. In addition, additives other than the above-mentioned fillers may be added to the composition for a resin magnet of the present invention without departing from the spirit of the present invention.

Example 1 A magnetic piece was manufactured under the following conditions. Extrusion speed during melting of resin magnet composition
5 m / min, temperature of melting cylinder 1 120 ° C., temperature of orientation die 2 115 ° C., position L of concentrated portion 5B of magnetic metal 5
1 = 3 mm, the height of the concentrated portion 5B of the magnetic metal 5 is 3 mm, the outer diameter of the concentrated portion 5B of the magnetic metal 5 is 3 mm, the current applied to the magnetic pole is 10A, and the generated magnetic field is 135000 gauss. The surface magnetic force was 1050 gauss. <Embodiment 2> The position L1 of the concentrated portion 5B of the magnetic metal 5 = 0.
The magnetic piece was manufactured in the same manner as in Example 1 except that the thickness was 5 mm. The surface magnetic force of the obtained magnetic piece 4 was 1100 gauss. <Embodiment 3> The above conditions were the same as those in Embodiment 1, and the total length L2 of the alignment die 2 was set to 60 mm and 30 mm.
The experiment was performed when the diameter was 0 mmφ. In each case, the surface magnetic force of the obtained magnetic piece was 1 in the same manner as in Example 1.
050 gauss. According to these results, the concentrated portion 5B of the magnetic metal 5 is placed in the product cavity 8 at a position where a high surface magnetic force is to be obtained in the product cavity 8 only near the exit portion on the concentrated magnetic pole 3A side.
It will be understood that it is sufficient to arrange them adjacent to.

Although the embodiment of the present invention has been described in detail above, the shape of the melting cylinder,
Form, extrusion form, heat retention form, mixing and mixing of molten mixture, magnetic pole arrangement form, orientation die shape and its shape, cross section of product cavity, etc. The installation form and the like can be appropriately adopted.

[0020]

As described above in detail, according to the present invention, there is provided a method for manufacturing a magnet molded product in which a molten mixture of a magnetic powder and a resin binder is extruded into a magnetic field to obtain a magnet molded product. The molten mixture is extruded through an orientation die, which is arranged in a magnetic pole by forming a molding die, and where a high surface magnetic force is to be obtained in a product cavity, and where a concentrated portion of a magnetic metal is disposed adjacent only to an exit portion on the concentrated magnetic pole side only near an outlet portion. By doing so, it is not necessary to provide a concentrated portion of the magnetic metal on the concentrated magnetic pole side over the entire length of the alignment die. Therefore, the electromagnetic piece which is an example of the magnetic pole used for forming the magnetic field is small, and the applied current is small. It is possible to satisfy various functions such as drawing, high magnetization, orientation, shape stabilization, etc. even if the current is small.

Therefore, conventionally, a common sense countermeasure for stabilizing the shape for eliminating the above-mentioned curvature is provided. The land length of the exit portion of the orientation die, which is rather detrimental to the manufacture of the magnetic roller, is used. It is not necessary to take a large amount, and even if the electromagnet which is an example of the orientation die or the magnetic pole is small, a sufficiently strong surface magnetic force can be obtained, so that a small amount of applied current is required and a low-cost manufacturing method of a magnet molded product. And its device. As described above, according to the present invention, a magnet capable of obtaining a high surface magnetic force, achieving downsizing of an alignment die and downsizing of an electromagnet as an example of a magnetic pole, and requiring a small applied current. A method and apparatus for manufacturing a molded product are provided.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows one embodiment of a method for manufacturing a magnet molded product and an apparatus therefor according to the present invention. FIG. 1 (A) is an overall sectional view of an extrusion apparatus, and FIG. It is an exit side front view.

FIG. 2 is a side sectional view and a front view of a magnetic roller as a product, showing an embodiment of a magnet molded product manufacturing apparatus according to the present invention.

FIG. 3 shows one embodiment of the apparatus for manufacturing a magnet molded product of the present invention, and is an explanatory view of magnetization of a magnetic piece near an exit of an orientation die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting cylinder 2 Orientation die 3 Magnetic pole 3A Concentrated magnetic pole 3B Opposing magnetic pole 4 Magnetic piece 4A-4D Magnetic drum piece 5 Magnetic metal upper mold 5B Magnetic metal concentrated part 6 Magnetic metal lower mold 7A Left nonmagnetic metal 7B Right nonmagnetic metal 8 Product Cavity 9 Shaft 10 Magnetic roller 11 Molten mixture (Molten resin magnet material) H Magnetization direction dimension of magnetic metal concentrated portion

Continued on the front page F term (reference) 4F207 AA04 AA11 AA13 AA29 AA49 AC04 AE04 AG06 AH04 AJ02 AJ11 KA07 KA17 KF01 KL63 4G054 AA07 BD14 4K018 CA04 CA32 KA46 5E062 CC01 CD02 CD05 CE03 CE07 CF02

Claims (8)

[Claims] 1. A method for manufacturing a magnet molded product, wherein a molten mixture of a magnetic powder and a resin binder is extruded into a magnetic field to obtain a magnet molded product, wherein a magnetic metal for orienting the magnetic powder at an outlet of a product cavity is provided. Extruding the molten mixture through an orientation die disposed on a concentrated magnetic pole side in a magnetic pole constituting a die for extrusion molding. 2. The method according to claim 1, wherein a distance between the magnetic metal and an outlet of the product cavity is 10 mm or less. 3. The method according to claim 1, wherein the length of the magnetic metal in the extrusion direction is 1/3 to 1/50 of the length of the orientation die. . 4. The method for producing a magnet molded product according to claim 1, wherein the magnet molded product is a magnetic piece for a magnetic roller. 5. An apparatus for manufacturing a magnet molding, wherein a molten mixture of a magnetic powder and a resin binder is extruded into a magnetic field to obtain a magnet molding, wherein a magnetic metal for orienting the magnetic powder at an outlet of a product cavity is provided. Wherein the molten mixture is extruded through an orientation die disposed on a concentrated magnetic pole side in a magnetic pole constituting a die for extrusion molding. 6. The apparatus according to claim 5, wherein a distance between the magnetic metal and an outlet of the product cavity is 10 mm or less. 7. The apparatus according to claim 5, wherein the length of the magnetic metal in the extrusion direction is 1/3 to 1/50 of the length of the alignment die. . 8. The apparatus according to claim 5, wherein the magnet molded product is a magnetic piece for a magnetic roller.