JP2001015319A - Manufacture of resin magnet composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a manufacturing method of resin magnet composition which can omit the grinding process of resin materials and reduce manufacturing cost, when pellet type resin magnet composition is manufactured, by mixing and dispersing magnetic power in a resin binder and performing extrusion molding. SOLUTION: In this manufacturing method of a resin magnet composition, pellet-type binder resin and magnetic powder are batch compounded and mixed, the obtained mixture is supplied to a kneading extruder by a constant amount feeder, and extrusion molding is conducted, thereby obtaining pellet type molding material for a resin magnet, where magnetic powder is mixed and dispersed in a resin binder. A grinding process for the resin material is omitted, and manufacturing cost of the resin magnet composition can be reduced. Moreover, a resin magnet composition of high quality which can obtain a resin magnet having satisfactory magnetic characteristics can be obtained surely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet resin obtained by mixing and dispersing magnetic powder in a resin binder, which is used as a molding material for a resin magnet molded product such as a magnet roller used in an electrophotographic apparatus or an electrostatic recording apparatus. The present invention relates to a method for producing a magnet composition.

[0002]

2. Description of the Related Art A resin magnet in which a magnetic powder such as ferrite or a rare earth magnet is mixed and dispersed in a synthetic resin binder is molded into an appropriate shape and magnetized to a desired magnetic property. It is used in various fields such as a magnet roller of an electrophotographic apparatus and an electrostatic recording apparatus, and a magnet for a motor. Such a resin magnet is prepared by mixing and dispersing magnetic powder in a resin binder in advance and forming into a pellet shape by extrusion molding or injection molding to form a desired shape and obtain desired magnetic characteristics. It is manufactured by magnetizing.

Conventionally, in order to obtain a resin magnet such as the above magnet roller, a pellet-shaped resin magnet composition to be subjected to injection molding or extrusion molding is prepared by mixing a binder resin and magnetic powder, extruding the mixture, and forming a pellet-shaped resin magnet. It is manufactured by molding. In this case, the binder resin is usually distributed in the form of pellets. For the following reasons, the pellet resin material is conventionally pulverized and once pulverized, and then mixed with the magnetic powder. Production of pellet-shaped molding materials by extrusion molding has been performed.

[0004] That is, the reason why the resin material in the form of pellets is once pulverized is as follows. Whereas the magnetic powder is a powder, when a pellet-shaped binder resin is used, the magnetic powder and the binder resin are separated at the time of kneading and are put into a kneader, and the composition ratio of the magnetic powder in the obtained pellet is reduced. In some cases, the mixing and kneading of the magnetic powder and the binder resin become insufficient, and in the worst case, the mixing and kneading cannot be performed. When a resin composition is produced using a pellet-shaped resin binder, the supply accuracy of the magnetic powder and the resin decreases, and the extrusion speed fluctuates, so that stable production may not be performed. When the composition ratio of the magnetic powder in the obtained pellets fluctuates, the magnetic properties of the product molded using the same vary, and not only does the quality deteriorate in terms of magnetic properties, but also
This may cause a problem such as a decrease in yield and a frequent occurrence of defective products.

However, this method requires a pulverizer for pulverizing the resin material in the form of pellets, which increases the equipment cost, and also increases the cost of preparing the raw material for the pulverization step. However, this is one of the causes for increasing the manufacturing cost of the resin magnet.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a process for pulverizing a resin raw material in producing a pellet-shaped resin magnet composition by mixing and dispersing magnetic powder in a resin binder and extruding the mixture is described. An object of the present invention is to provide a method for producing a resin magnet composition that can be omitted to reduce the production cost.

[0007]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that a pellet binder resin as a resin raw material and a magnetic powder are batch-blended. By mixing and feeding the obtained mixture to an extruder at a relatively high speed using a quantitative feeder and extruding, even if the pulverizing step of the resin raw material is omitted,
A pellet-shaped resin magnet composition in which magnetic powder is mixed and dispersed in a binder resin can be produced at a practically acceptable level. The resin magnet composition is subjected to injection molding or extrusion molding to form a resin magnet. By doing so, it has been found that a resin magnet such as a magnet roller having sufficient performance can be manufactured at low cost, and the present invention has been completed.

Accordingly, the present invention provides a method for producing a pellet-shaped resin magnet composition in which magnetic powder is mixed and dispersed in a resin binder by mixing and extruding a magnetic powder into a resin binder to form a pellet. In the above, the pelletized binder resin and the magnetic powder are batch-blended and mixed, and the resulting mixture is fed to a kneading extruder with a quantitative feeder and extruded, whereby the magnetic powder is mixed and dispersed in the resin binder. It is intended to provide a method for producing a resin magnet composition, characterized by obtaining a molding material for a pellet-shaped resin magnet.

The present inventor further studied and found that a mixture obtained by batch-mixing pellet-shaped binder resin and magnetic powder was supplied to an extruder by a fixed-quantity feeder to reduce the extrusion speed when forming pellets. Average volume of pellets 10
By setting the weight to 30 kg / h or more per mm ³ , the uniform dispersibility of the magnetic powder can be further improved, and by mixing the obtained pellet-shaped resin magnet composition and subjecting it to molding of the resin magnet, It is possible to obtain a resin magnet having performance not inferior to the case of using the resin magnet composition that has undergone the pulverizing step, and in some cases, has better magnetic properties than those using the resin magnet composition that has undergone the pulverizing step. It has been found that a resin magnet can be obtained.

Therefore, in a preferred embodiment of the present invention, the extruding speed of the kneading extruder is 30 kg / h or more per 10 mm ³ of the average volume of the pellets.
The manufacturing method of the resin magnet composition described, and after extrusion molding,
The method for producing a resin magnet composition according to claim 1 or 2, wherein the obtained pellet-shaped resin magnet composition is mixed and homogenized.

Hereinafter, the present invention will be described in more detail.
The method for producing the resin magnet composition of the present invention, as described above,
The pelletized binder resin of the resin raw material is mixed with the magnetic powder in batches without being pulverized and mixed, and this mixture is supplied to an extruder by a quantitative feeder to be formed into pellets.

The binder resin used as the resin raw material is not particularly limited as long as it can be extruded, and is appropriately selected depending on the intended use of the resin magnet and the like. Are polyamide resins such as nylon 6 and nylon 12, polystyrene resin, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyphenylene sulfide resin (PPS), ethylene-vinyl acetate copolymer (EV)
A), ethylene-ethyl acrylate copolymer resin (E
EA), epoxy resins, ethylene-vinyl alcohol copolymer (EVOH), polyolefins such as polypropylene and polyethylene and derivatives thereof, and reactions of maleic anhydride groups, carboxyl groups, hydroxyl groups, glycidyl groups, etc. in the structures of these polyolefins. Thermoplastic resins, such as modified polyolefins, into which functional groups having properties are introduced, may be used alone or in admixture of two or more. Of these, polyamide, polyphenylene sulfide, ethylene ethyl acrylate copolymer, and ethylene vinyl acrylate copolymer are particularly preferably used from the viewpoint of moldability, magnetic properties, mechanical properties, price, and the like.

These resin raw materials are usually distributed in the form of pellets, and in the present invention, these resin raw materials are used in the form of pellets by mixing with magnetic powder described later. In this case, although not particularly limited, the size of the pellet-shaped resin raw material is preferably φ5 × 5 mm or less, particularly preferably φ4 × 4 mm to φ1 × 1 mm. If it is larger than this, it may not be possible to mix the powder with the magnetic powder.
When a plurality of resin raw materials are mixed and used, it is preferable that the pellets of each resin raw material have the same size as much as possible.

Next, as the magnetic powder to be mixed with the resin raw material, a known magnetic powder generally used for a resin magnet can be used. Specifically, ferrite powder such as Sr ferrite, Ba ferrite, or the like can be used. Nd-Fe-B alloy, S
Rare earth alloy powders such as m-Fe-N alloy, Sm-Co alloy and Ce-Co alloy are exemplified. This magnetic powder,
Any of anisotropic and isotropic materials may be used, and it can be appropriately selected according to the intended molding method and application of the resin magnet.

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 material.
In this case, as the coupling agent, γ-ureidopropyltriethoxysilane, γ-benzylaminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-
Various coupling agents such as a silane coupling agent such as aminopropyltrimethoxysilane or an ethane-based coupling agent can be used.

Here, the magnetic powder is not particularly limited, but has an average particle size of 0.5 to 500 μm, particularly 1 to 500 μm.
If the particle size of the magnetic powder is too small, it is difficult to mix with the resin material, and the uniformity of the magnetic powder may be extremely reduced. If it is too much, it may be difficult to obtain a resin magnet having good magnetic properties.

In the production method of the present invention, the above-mentioned pelletized binder resin as a resin raw material and the above-mentioned magnetic powder are batch-blended and mixed, and the mixture is fed to an extruder by a fixed-quantity feeder to be formed into pellets. It is.

In this case, the mixing ratio of the binder resin and the magnetic powder is not particularly limited, and is appropriately selected according to the magnetic force required for the target resin magnet.
For example, the proportion of the magnetic powder is preferably 70 to 97% by weight, and usually 80 to 95% by weight. The amount of the mixture in the batch blending is not particularly limited, but is 5 to 500 kg, particularly 10 to 300 k as a mixture.
It is preferably about g from the viewpoint of mixing operability and uniformity of the obtained mixture.

Here, if necessary, the mixture may contain
In addition to the binder resin and the magnetic powder, a filler having a large reinforcing effect such as mica, whisker, talc, carbon fiber, glass fiber, or the like can be appropriately added as long as the object of the present invention is not hindered. That is, when the magnetic force required for the target resin magnet is relatively low and the filling amount of the magnetic powder is small, the rigidity of the target molded product tends to be low, and in such a case, the rigidity is supplemented. For this reason, a molded product can be reinforced by adding a filler such as mica or whisker. As the filler suitably used in the present invention, mica or whisker is preferable. As the whisker, a non-oxide whisker made of silicon carbide, silicon nitride or the like, ZnO, Mg
Metal oxide whiskers made of O, TiO ₂ , SnO ₂ , Al ₂ O _3, etc., potassium titanate, aluminum borate,
Examples thereof include double oxide whiskers made of basic magnesium sulfate and the like. Of these, double oxide whiskers are particularly preferably used because they can be easily combined with plastic. The mixing ratio when the above filler is used is not particularly limited, but is usually 0.1 to 10% by weight, particularly about 1 to 5% by weight of the whole molding material.
In addition, as long as the object of the present invention is not deviated, an appropriate additive may be blended.

The method of mixing the above-mentioned additives such as the binder resin, the magnetic powder and the filler in a batch is not particularly limited, and the mixing can be carried out using a known mixer. For example, using a stirring blade type mixer, 100 to 1
What is necessary is just to mix under conditions of 000 rpm.

Next, the mixture obtained by mixing and mixing the above batches is supplied to an extruder using a quantitative feeder, and the mixture is kneaded and extruded by a kneader provided in the extruder to obtain a pellet-shaped resin magnet composition. .

In this case, the extrusion speed during extrusion molding is not particularly limited, but the average pellet volume is 10 m.
30 kg / h or more per m ³ , especially 50 to 500 kg / h
h is preferable. As described above, by performing extrusion molding at a relatively high speed, the flow of the resin due to the decrease in the extrusion speed is prevented, and the occurrence of a defect due to the pulsation of the resin is prevented. A uniformly dispersed molding material can be obtained more reliably. The type of the extruder is not particularly limited, and a single-screw or twin-screw kneading extruder can be used as appropriate.

The other molding conditions such as the resin temperature and the cylinder temperature during kneading are not particularly limited, and can be set as appropriate according to the type of the binder resin.
Further, the size and shape of the obtained pellet can be appropriately selected according to the size and shape of the target resin magnet, the molding method and conditions, and the like.

In the present invention, although not particularly limited, the pellet-shaped resin magnet composition thus obtained is further mixed to obtain the desired resin magnet by injection molding or extrusion molding. Is preferably provided. As a result, even if there is a slight variation in the filling amount of the magnetic powder between the pellets, this is offset by the random mixing of a large number of pellets, and a molding material having extremely high uniformity as a batch unit is obtained. Can be.

The resin magnet composition obtained by the production method of the present invention is used for forming resin magnet parts used in electrophotographic devices and electrostatic recording devices, and in particular, a magnet roller used in a developing mechanism of these devices. It is preferably used as a molding material, and the production method of the present invention can produce a high-quality molding material at a low cost, which can be sufficiently applied to applications requiring such advanced magnetic properties. It is. Of course, the use of the resin magnet composition obtained by the production method of the present invention is not limited to this,
It is also suitably used for other applications, such as a molding material for resin magnet parts for motors.

[0026]

As described above, according to the method for producing a resin magnet composition of the present invention, the production cost of the resin magnet composition can be reduced by omitting the step of pulverizing the resin raw material, and moreover, it is preferable. It is possible to reliably obtain a high-quality resin magnet composition that can obtain a resin magnet having excellent magnetic properties.

[0027]

EXAMPLES Hereinafter, the effects of the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1] Anisotropic Sr ferrite (NF110, manufactured by Nippon Benzaru Co., Ltd., average particle size 1.4 µm) 18
kg of coupling agent (A11 manufactured by Nippon Unicar Co., Ltd.)
60) The mixture was stirred with a high-speed mixer together with 180 g to perform surface treatment. In addition, a commercially available pellet (φ2 × 3m
m) Polyamide-6 (1010X manufactured by Ube Industries, Ltd.)
2) After mixing 2.225 kg, the mixture was supplied to a kneader (biaxial kneader) using a fixed-quantity feeder, and the average volume of the pellets was 1
It was extruded at a rate of 50 kg / h per 0 mm ³ and cut into a predetermined size to obtain 15 kg of a pellet-shaped product having a size of 3 × 3 mm. The obtained pellet-shaped molded product was mixed and homogenized by a rotary mixer to obtain a resin magnet composition.

Part (15 g) of the obtained resin magnet composition
Was taken out, and the content of the ferrite powder was measured. As a result, it was confirmed that the composition was 88.87 to 89.12%, almost the same as the composition.

On the other hand, using the obtained resin magnet composition, a resin magnet (a cylindrical molded product of φ15 mm × 240 mm) was molded by an injection molding machine, and the surface magnetic force after magnetization was measured. ~ 1150 (Gauss), and a good product with little variation in magnetic force was obtained.

Comparative Example A resin magnet composition was produced in the same manner as in Example 1 except that pelletized polyamide-6 was crushed into particles having an average particle diameter of about 200 μm using a crusher and then used. did.

Example 1 of the obtained resin magnet composition
The ferrite content was measured in the same manner as
At 88.95 to 89.14%, the dispersion was almost the same as that of Example 1. In addition, a resin magnet molded product was molded by injection molding in the same manner as in the example, and the surface magnetic force after magnetization was measured. The surface magnetic force was 1100 to 1150 (gauss).
s), and the magnetic properties of the obtained resin magnet were not different from those of the examples.

As described above, the resin magnet composition of the above example obtained by using the resin raw material in the form of pellets without pulverization was obtained by the conventional method (comparative example) in which the resin raw material was pulverized and then used. It has the same quality as the obtained resin magnet composition, and it has been confirmed that according to the present invention, the production cost can be reduced by omitting the pulverizing step.

[0034] [Example 2] to slightly slow the feed rate of the metering feeder, the average volume of the pellet 10 mm ³ per 2
A resin magnet composition was manufactured in the same manner as in Example 1 except that the extrusion was performed at a speed of 0 kg / h.

Example 1 of the obtained resin magnet composition
The ferrite content was measured in the same manner as
It was 88.52 to 89.23%, and the variation was slightly larger than that in Example 1, but at a practically no problem level.

The resin magnet composition was injection-molded in the same manner as in Example 1 to form a molded resin magnet, and the surface magnetic force after magnetization was measured.
0 (gauss), and the variation of the magnetic force was somewhat large, but at a level that did not cause any problem in practical use.

Example 3 A resin magnet composition was produced in the same manner as in Example 1 except that the pellets after extrusion were not mixed and homogenized by a rotary mixer. When the ferrite content of the obtained resin magnet composition was measured in the same manner as in Example 1, the content was 88.17 to 91.34.
%, And the variation was slightly large, but at a level that hardly caused a problem in ordinary use. In addition, a resin magnet molded article was molded by injection molding in the same manner as in Example 1, and the surface magnetic force after magnetization was measured.
１７０1170 (Gauss), and the variation in magnetic force was slightly large, but the pulverizing step can be omitted,
It was more advantageous in cost than the conventional method (Comparative Example).

Claims (6)

[Claims] 1. A method for producing a pellet-shaped resin magnet composition in which magnetic powder is mixed and dispersed in a resin binder by mixing and extruding a magnetic powder into a resin binder to form a pellet. The binder resin and the magnetic powder are batch-blended and mixed, and the obtained mixture is supplied to a kneading extruder by a quantitative feeder, and is extruded to form a pellet in which the magnetic powder is mixed and dispersed in the resin binder. A method for producing a resin magnet composition, comprising obtaining a molding material for a resin magnet. 2. The method for producing a resin magnet composition according to claim 1, wherein an extrusion speed of the kneading extruder is 30 kg / h or more per an average volume of 10 mm ³ per pellet. 3. The method for producing a resin magnet composition according to claim 1, wherein after extrusion molding, the obtained pellet-shaped composition is mixed and homogenized. 4. The resin according to claim 1, wherein the resin binder is a mixed resin comprising one or more selected from polyamide, polyphenylene sulfide, ethylene ethyl acrylate copolymer, and ethylene vinyl acrylate copolymer. A method for producing the resin magnet composition according to claim 1. 5. The size of the pellet-shaped binder resin is as follows:
One particle is φ5 × 5 mm or less, and the average particle size of the magnetic powder is 0.1 mm.
The method for producing a resin magnet composition according to any one of claims 1 to 4, wherein the thickness is 5 to 500 µm. 6. The method for producing a resin magnet composition according to claim 1, wherein the mixing ratio of the magnetic powder is 70 to 97% by weight.