JP2001240740A - Composition for synthetic resin magnet and resin magnet molded item - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for a synthetic resin magnet which shows excellent melt flowability, can keep good melt flowability even when a large amount of a magnetic powder is used and can achieve a high magnetic force of the molded item without decreasing moldability. SOLUTION: A composition for a synthetic resin magnet is obtained by dispersing and mixing a magnetic powder in a resin binder, wherein the resin binder contains a major resin composed of a thermoplastic resin and a polymerized aliphatic acid-based polyamide (except for an elastomer).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is obtained by mixing and dispersing magnetic powder in a resin binder, and is suitably used as a molding material for a resin magnet molding such as a magnet roller used in an electrophotographic apparatus or an electrostatic recording apparatus. The present invention relates to a composition for synthetic resin magnets, and a molded resin magnet formed by molding the composition for synthetic resin magnets into a desired shape.

[0002]

2. Description of the Related Art Conventionally, as a developing roller for visualizing an electrostatic latent image on a latent image holding member such as a photosensitive drum, in an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus.
A so-called jumping phenomenon, in which a magnet roller formed of a resin magnet is provided in a rotating sleeve, and a magnetic developer (toner) carried on the surface of the sleeve flies onto the latent image holding member by the magnetic force characteristics of the magnet roller, There is known a developing method for supplying a toner to the surface of a latent image holding member to visualize an electrostatic latent image.

Conventionally, the above-mentioned magnet roller is prepared by injection molding or extrusion molding of a composition for a synthetic resin magnet in which a magnetic powder is mixed with a binder of a thermoplastic resin using a mold having a magnetic field formed around the composition. It is manufactured by forming it into a roller shape and magnetizing it to desired magnetic properties.

Further, 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. A desired magnetic force pattern is also formed by molding a plurality of magnet pieces with magnetized magnetic poles from the above-described composition for a synthetic resin magnet and pasting them around a shaft.

[0005] As a composition for a resin magnet for obtaining such a magnet roller, a magnetic powder such as a ferrite or a rare earth magnet is prepared by mixing a magnetic powder such as a polyamide resin such as polyamide-6, polyamide-12, or a polypropylene resin or the like with a resin binder. What has been mixed and dispersed is conventionally used.

[0006]

However, with the recent sophistication, high speed, and high accuracy of OA equipment, the demand for high magnetic force of the magnet roller has been increasing, and also in other fields. Higher magnetic force of resin magnet is always required.

In order to meet this demand, it is necessary to increase the filling amount of the magnetic powder in the composition for the synthetic resin magnet constituting the magnet roller and the like. The fluidity at the time of melting is reduced, and the molding processability is significantly reduced, resulting in problems such as variation in magnetic force and reduction in dimensional accuracy in the obtained molded product. For this reason, the filling amount of the magnetic powder is naturally limited, and at present, it is not possible to fill a sufficient amount of the magnetic powder to satisfy the demand for higher magnetic force.

The present invention has been made in view of the above circumstances, and is excellent in fluidity at the time of melting, can maintain good melt fluidity even when the filling amount of magnetic powder is increased, and lowers moldability. An object of the present invention is to provide a composition for a synthetic resin magnet capable of achieving a high magnetic force of a molded product without the need, and a resin magnet molded product obtained by molding the composition for a synthetic resin magnet.

[0009]

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 magnetic powder is mixed and dispersed in a resin binder made of a thermoplastic resin to produce a synthetic resin. In the case of preparing a magnet composition, the melt fluidity of the composition can be effectively improved by adding and mixing, for example, a polymerized fatty acid-based polyamide represented by the following formula (1) in the resin binder. Even if the filling amount of the magnetic powder is increased to increase the magnetic force of the molded product, good melt fluidity can be maintained, without causing problems such as a decrease in molding processability due to a decrease in fluidity at the time of melting. The inventors have found that a resin magnet molded article having a high magnetic force can be obtained, and have completed the present invention.

[0010]

Embedded image [Wherein, R ₁ is HOOC (CH ₂ ) _n COOH (n = 7 or n = 8), C _m is diamine residue (m = 2 to 20), C _n is dimer acid residue (n =
20 to 48), a is an integer of 1 to 50, b is an integer of 1 to 50,
x represents an integer of 1 to 50, respectively]

Accordingly, the present invention provides a composition for a synthetic resin magnet in which a magnetic powder is dispersed and mixed in a resin binder, wherein the resin binder contains a main resin composed of a thermoplastic resin and a polymerized fatty acid polyamide. A composition for a synthetic resin magnet, particularly a composition for a synthetic resin magnet using the polymerized fatty acid-based polyamide represented by the above (1) as the polymerized fatty acid-based polyamide, and a composition for these synthetic resin magnets. An object of the present invention is to provide a resin magnet molded product obtained by molding the composition into a desired shape.

Hereinafter, the present invention will be described in more detail.
As described above, the composition for a synthetic resin magnet of the present invention is obtained by mixing and dispersing magnetic powder in a resin binder obtained by adding a polymerized fatty acid-based polyamide to a main resin composed of a thermoplastic resin.

The thermoplastic resin which is the main material of the binder resin includes polyamide resin (polyamide-6, polyamide-12, etc.), polystyrene resin, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyphenylene sulfide resin. (PPS), ethylene-vinyl acetate copolymer resin (EV
A), polyolefins such as ethylene ethyl acrylate resin (EEA), epoxy resin, ethylene-vinyl alcohol copolymer resin (EVOH), polypropylene resin (PP), polyethylene, polyethylene copolymer, and the like. Modified polyolefins into which a reactive functional group such as a maleic acid group, a carboxyl group, a hydroxyl group, or a glycidyl group has been introduced, and one or more of these can be used.

The amount of the main resin is not particularly limited, but is preferably about 1 to 20% by weight, and more preferably 4 to 16% by weight of the whole resin magnet composition. If the compounding amount of the main resin is less than 1% by weight, it may not be possible to obtain a sufficient melt fluidity even if a polymerized fatty acid-based polyamide described below is added, and the obtained resin magnet molded product may be extremely poor. May be brittle.
On the other hand, if it exceeds 20% by weight, the filling amount of the magnetic powder becomes relatively small, and it may be difficult to achieve high magnetic force.

Next, as the above-mentioned polymerized fatty acid-based polyamide to be added to the main resin, any polyamide can be used as long as the object of the present invention can be achieved, and particularly, it is represented by the following formula (1). Are preferably used.

Embedded image [Wherein, R ₁ is HOOC (CH ₂ ) _n COOH (n = 7 or n = 8), C _m is diamine residue (m = 2 to 20), C _n is dimer acid residue (n =
20 to 48), a is an integer of 1 to 50, b is an integer of 1 to 50,
x represents an integer of 1 to 50, respectively]

Here, each symbol in the above equation (1) is
As described further, R ₁Is HOOC (CH_Two)_nCOOH
Azelaic acid (n = 7) or sebacic acid (n
= 8), in which case it contains azelaic acid (n = 7)
Blocks and blocks containing sebacic acid (n = 8) are mixed
It may be. Also, C_mIs the diamine of m = 2-20
It is a residue, specifically, ethylenediamine, 1,4-di
Aminobutanehexamethylenediamine, nonamethylenedi
Amine, undecamethylenediamine, dodecamethylenedi
Amine, 2,2,4-trimethylhexamethylenedia
Min, bis- (4,4'-aminocyclohexyl) meth
, Meta-xylene diamine and the like;_nIs Dima
-Acid residue n = 20-48 dimer residue, specific
Include dimers such as oleic acid, linoleic acid and erucic acid
No. Further, a in the formula is an integer of 1 to 50, b is 1
X is an integer of 1 to 50, and x is an integer of 1 to 50. What
Although not particularly limited, the expression (1)
The molecular weight of the polymerized fatty acid-based polyamide is 1000 to 6
5000 (number average molecular weight), especially 5000-25000
It is preferred that

As the polymerized fatty acid-based polyamide represented by the formula (1), "PA-PA" manufactured by Fuji Kasei Co., Ltd. is specifically used.
30L "," PA-30 "," PA-40L "," PA
-40 "," PA-30R "," PA-30H "," P
A-50R "," PA-50M "," PA-60 ",
"PA-160", "PA-260" and the like. In addition, although it is also possible to use a thing other than said Formula (1) as a polymeric fatty acid type polyamide, an elastomer is excluded in this invention.

The amount of the polymerized fatty acid polyamide is as follows:
It is appropriately selected depending on the kind of the main resin, the filling amount of the magnetic powder, and the like, and is not particularly limited, but is usually 0.1 to 20% by weight, and especially 0.1 to 20% by weight of the whole resin magnet composition. ~
Preferably it is 5% by weight. If the addition amount is less than 0.1% by weight, the effect of improving the melt fluidity may not be sufficiently obtained. On the other hand, if it exceeds 20% by weight, the filling amount of the magnetic powder becomes relatively small. In some cases, sufficient magnetic force characteristics cannot be obtained.

Next, as the magnetic powder mixed and dispersed in the binder resin containing the main resin and the polymerized fatty acid-based polyamide, a known magnetic powder conventionally used as a magnetic powder for a resin magnet may be used. Yes, specifically, S
ferrite powder such as r ferrite, Ba ferrite, alnico alloy, Sm-Co alloy, Nd-Fe-B alloy,
Rare earth alloy powders such as Sm-Fe-N alloys and Ce-Co alloys can be exemplified.

The magnetic powder used in the present invention is not particularly limited, but is usually an average powder from the viewpoint of the melt fluidity of the obtained resin magnet composition, the orientation of the magnetic powder, the filling rate, and the like. Particle size 0.05-300 μm, especially 0.1-1
It is preferably about 00 μm.

The above magnetic powder can be subjected to a known pretreatment if necessary, and can be blended into a composition for a synthetic resin magnet. In this case, although not particularly limited, it is preferable to perform the coupling treatment using a known coupling agent such as a silane coupling agent or a titanate-based coupling agent, and the coupling treatment is performed. By using the magnetic powder, 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 coupling agent include isopropyl bis (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl / aminoethyl) 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 (dioctylpyrophosphate) Oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate and the like are listed. Phosphate) titanate is particularly preferably used.

The amount of the magnetic powder is appropriately selected according to the strength of the magnetic force required for the target molded product, and is not particularly limited. To 99% by weight, and in the present invention, even when the magnetic powder is highly filled in an amount exceeding 90% by weight, the melt flowability of the composition can be maintained satisfactorily, and a resin magnet molded article having a high magnetic force can be obtained. It can be obtained with good moldability. Also,
In the present invention, as described above, a remarkable effect is obtained when the magnetic powder is highly filled. However, the composition for a synthetic resin magnet of the present invention has a compounding amount of the magnetic powder of about 80 to 90% by weight. Even when the filling is not high, it is advantageous in terms of uniform dispersion of the magnetic powder.

The composition for a synthetic resin magnet of the present invention contains the above-mentioned main resin, a polymerized fatty acid-based polyamide, and a magnetic powder, and is not particularly limited. It is preferable to add an appropriate amount of an antioxidant to prevent oxidative deterioration. The antioxidant is not particularly limited, and a known one can be used, and specific examples thereof include hindered phenol-based, hindered amine-based, and phosphorus-based antioxidants.

The amount of the antioxidant to be added is appropriately selected according to the type of the antioxidant, the type of the binder resin, and the like, and is not particularly limited. 0.1-20% by weight, particularly preferably 0.1-3% by weight.

The composition for a synthetic resin magnet of the present invention may optionally contain an appropriate amount of a dispersant, a lubricant, a plasticizer or the like for dispersing the magnetic powder.

As the above-mentioned dispersant, a phenol-based or amine-based dispersant can be used, and as the above-mentioned lubricant, waxes such as paraffin wax and microstalin wax; fatty acids such as stearic acid and oleic acid; These metal salts (calcium stearate, zinc stearate, etc.) are preferably used, and as the plasticizer, a monoester or polyester plasticizer, an epoxy plasticizer and the like are suitably used.

Further, to the composition for a synthetic resin magnet of the present invention, a filler having a large reinforcing effect such as mica, whisker or talc, carbon fiber, glass fiber or the like is appropriately added as long as the object of the present invention is not hindered. be able to. That is, when the magnetic force required for the molded product is relatively low and the filling amount of the magnetic powder is relatively small, the rigidity of the molded product is likely to be low. In such a case, mica or A molded product can be reinforced by adding a filler such as whisker.
In this case, the filler preferably used in the present invention is preferably mica or whisker, and the whisker is a non-oxide whisker made of silicon carbide, silicon nitride, or the like;
Metal oxide whiskers made of nO, MgO, TiO ₂ , SnO ₂ , Al ₂ O _{3 and the} like, and double oxide whiskers made of potassium titanate, aluminum borate, basic magnesium sulfate, etc., are exemplified. Among them, double oxide whiskers are particularly preferably used because they can be easily combined with plastic.

The amount of these fillers used is not particularly limited, but is usually about 1 to 50% by weight, especially about 5 to 20% by weight, based on the total composition of the synthetic resin magnet. . Incidentally, the composition for a synthetic resin magnet of the present invention, as long as it does not deviate from the object of the present invention, it is possible to add additives other than the magnetic powder dispersant, lubricant, plasticizer and filler, for example, An appropriate amount of an organotin-based stabilizer or the like can be added as needed.

The resin magnet molded article of the present invention is formed by using the above-described composition for a synthetic resin magnet of the present invention, whereby it has excellent dimensional accuracy, small variation in magnetic force, and high magnetic force. Can be achieved. That is, since the composition for a synthetic resin magnet of the present invention can maintain good melt fluidity even when a large amount of magnetic powder is filled, even if a large amount of magnetic powder is filled to achieve high magnetic force, It can flow well in the mold cavity during molding,
A resin magnet molded article such as a magnet roller having a high magnetic force and a high performance can be obtained with good moldability without causing poor orientation or filling of the magnetic powder in the mold, uneven filling, or the like.

In order to obtain the resin magnet molded product of the present invention, the above-described composition for a synthetic resin magnet of the present invention may be kneaded and melted and molded. The molding method at that time depends on the resin magnet molded product. An appropriate molding method such as an injection molding method, an extrusion molding method, and a compression molding method can be employed.

The resin magnet molded article of the present invention is not particularly limited, but is required to have a high magnetic force and high magnetic properties, so that it is used for a developing mechanism of an electrophotographic apparatus or an electrostatic recording apparatus. The magnet roller used is preferably used. Usually, the magnet roller is configured to include a roller body made of a resin magnet and shaft portions protruding from both ends of the roller body. In this case, a shaft made of metal or the like is set in a mold and the The roller body may be formed around the outer periphery with the synthetic resin magnet composition, or the shaft and the roller body may be integrally formed with the synthetic resin magnet composition. Furthermore, when high and complicated magnetic properties are required, a plurality of resin magnet pieces are formed using the resin magnet composition, and these are bonded to the outer periphery of a shaft made of metal or the like to form a roller body. May be. In this case, of course, all of the resin magnet pieces may be formed into the resin magnet molded article of the present invention obtained by molding the composition for a synthetic resin magnet of the present invention. However, in some cases, only the resin magnet pieces requiring particularly high magnetic force may be used. The invention resin magnet molded article may be used. The magnetization of the magnet roller may be performed simultaneously with molding by forming a magnetic field around the mold, or may be performed using a known magnetizing machine after molding.

[0034]

According to the composition for a synthetic resin magnet of the present invention, the flowability at the time of melting can be improved by adding a polymerized fatty acid-based polyamide, and the composition can be obtained by injection molding, extrusion molding, compression molding or the like. The moldability at the time of obtaining a resin magnet molded article is improved, and it is possible to satisfactorily cope with a high magnetic force due to high filling of magnetic powder without lowering the moldability.

[0035]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 Nd ₁₂ Fe ₇₈ C in atomic weight%
After pulverizing an Nd-based rare earth magnet alloy raw material powder having a composition of o ₄ B ₆ (“MQP-B” manufactured by General Motors Co., Ltd.) into a powder having an average particle diameter of 100 μm, a silane coupling agent (Nihon Yunika Co., Ltd.) ("A1100") to prepare a magnetic powder. 188 g of this magnetic powder
Nylon 12 (P3012 manufactured by Ube Industries, Ltd.)
U "), 6.8 g, antioxidant (" IRGANOX MD 102 "manufactured by Ciba Specialty Chemicals Co., Ltd.)
4)) 3.5 g and a polymerized fatty acid-based polyamide (“PA-30L” manufactured by Fuji Kasei Co., Ltd.) 1.7 g were mixed, and “Laboplast Mill 50C150” manufactured by Toyo Seiki Co., Ltd. (capacity: 60)
cm ² ) and 50 rpm for 15 minutes under heating at 250 ° C.
The mixture was kneaded at a rotation speed of m to prepare a composition for a synthetic resin magnet. At this time, the change in the torque value of the melt during kneading was measured. The results are shown in FIG. In this case, the higher the torque value, the higher the viscosity of the melt and the worse the fluidity. FIG.
As shown in Table 1, in the first embodiment, the torque does not increase, that is, the viscosity does not increase even after 15 minutes.

Next, the melt flowability (MFR) of the obtained composition for a synthetic resin magnet was measured with a melt indexer (manufactured by Toyo Seiki Co., Ltd.), and found to be 72.7 g / 10 mi.
n (250 ° C., 5 kg), it had good melt fluidity.

Further, the composition for a synthetic resin magnet was injection-molded and magnetized to form a cylindrical test piece having a diameter of 20 mm and a height of 6 mm, and the magnetic energy product (BHmax) was measured to be 54.91 kJ. / M ³ and a high magnetic force.

[Comparative Example 1] The amount of nylon 12 was increased to 8.5 without using the polymerized fatty acid polyamide.
A composition for a synthetic resin magnet was prepared in the same manner as in Example 1 except that g was used. At this time, the change in the torque value of the melt during kneading was measured in the same manner as in Example 1. The results are shown in FIG. Further, in the same manner as in Example 1, the MFR value and the BHmax were measured.

As shown in FIG. 1, in this comparative example, no increase in torque during melting was observed, but the MFR value was 9.84 g / 10 min (250 ° C., 5 kg), and the fluidity was poor. And BHmax is also 51.73kJ / m
³ and inferior to Example 1 above.

[Example 2] 50.00 kg of Sr ferrite ("NF110" manufactured by Nippon Benzaru Kogyo Co., Ltd.), Ba ferrite ("DNP-S" manufactured by Nippon Bengara Kogyo Co., Ltd.) 2
0.55 kg was subjected to a surface treatment with 0.71 kg of a silane coupling agent (“A1160” manufactured by Nippon Unicar Co., Ltd.) to prepare a magnetic powder. This magnetic powder is transferred to nylon 6
(P1010 manufactured by Ube Industries, Ltd.) 12.5 kg,
0.42 kg of antioxidant (“IRGANOX 245” manufactured by Ciba Specialty Chemicals Co., Ltd.) and polymerized fatty acid polyamide (“PA-30” manufactured by Fuji Kasei Co., Ltd.)
L ") was mixed with 0.42 kg, kneaded with a twin-screw kneader, and then pelletized to obtain a pellet-shaped composition for a synthetic resin magnet.

The melt fluidity (MFR) of the obtained composition for synthetic resin magnet was measured with a melt indexer (manufactured by Toyo Seiki Co., Ltd.), and was 156.84 g / 10 min.
(270 ° C., 5 kg) and had good melt fluidity. Further, this synthetic resin magnet composition was injection-molded while applying a magnetic field to form a cylindrical resin magnet molded product having a diameter of 9.6 mm, and the surface magnetic force was measured.
表面 indicates the surface magnetic force.

[Comparative Example 2] A pellet-shaped product was prepared in the same manner as in Example 1 except that the amount of nylon 6 was increased by 0.42 kg to 12.92 kg without using the polymerized fatty acid-based polyamide. A composition for a synthetic resin magnet was prepared.

With respect to the obtained composition for a synthetic resin magnet,
The MFR value was measured in the same manner as in Example 2.
At 23.99 g / 10 min (270 ° C., 5 kg), the melt fluidity was inferior to that of Example 2. Also, a cylindrical resin magnet molded product was prepared using the obtained composition for a synthetic resin magnet in the same manner as in Example 2, and the surface magnetic force was measured. Was inferior.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in torque during kneading when a composition for a synthetic resin magnet is prepared in Example 1 and Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16C 13/00 F16C 13/00 A G03G 15/09 G03G 15/09 A H01F 7/02 H01F 7/02 H F term (reference) 2H031 AC18 3J103 EA02 FA15 FA18 FA30 GA02 GA52 GA57 GA58 HA03 HA16 HA22 HA41 HA46 4J001 DA01 DB02 DB04 DB05 DC12 EB03 EB13 EB71 EC03 EC13 FB06 FC06 GA11 HA01 HA02 HA05 JA20 4J002 BB031 BB041 BB041 BB041 BB041 BB041 BB041 CD001 CF061 CF071 CL011 CL031 CL032 CN011 DA006 DA086 DA116 DC006 DE066 DE196 EJ007 EN007 EW027 FD010 FD077 GR02

Claims (6)

[Claims] 1. A composition for a synthetic resin magnet in which magnetic powder is dispersed and mixed in a resin binder, wherein the resin binder contains a main resin composed of a thermoplastic resin and a polymerized fatty acid-based polyamide (excluding an elastomer). A composition for a synthetic resin magnet, comprising: 2. The resin magnet composition according to claim 1, wherein the polymerized fatty acid-based polyamide has a basic structure represented by the following structural formula (1). Embedded image [Wherein, R ₁ is HOOC (CH ₂ ) _n COOH (n = 7 or n = 8), C _m is diamine residue (m = 2 to 20), C _n is dimer acid residue (n =
20 to 48), a is an integer of 1 to 50, b is an integer of 1 to 50,
x represents an integer of 1 to 50, respectively] 3. The synthetic resin magnet composition according to claim 1, further comprising an antioxidant. 4. The composition for a synthetic resin magnet according to claim 3, wherein the mixing ratios of the magnetic powder, the main resin, the polymerized fatty acid-based polyamide, and the antioxidant are as follows. Magnetic powder 80-99% by weight Main resin 1-20% by weight Polymerized fatty acid polyamide 0.1-20% by weight Antioxidant 0.1-20% by weight 5. A resin magnet molded product obtained by molding the composition for a synthetic resin magnet according to any one of claims 1 to 4 into a desired shape. 6. The resin magnet molded product according to claim 5, wherein the molded product is a magnet roller used for a developing operation in an electrophotographic process.