JP2005217273A - Resin bonded magnet and composition therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a resin bonded magnet which has high fusion flowability and excellent moldability and the resin bonded type magnet which has superior mechanical strength. <P>SOLUTION: The composition for the resin bonded magnet is obtained by mixing rare-earth/transition metal-based magnetic powder (A) with a resin binder (B), and dispersing it. In the composition for the resin bonded magnet, the resin binder (B) consists of a polyamide resin mixture of 6/12 copolymerized nylon of 10,000 to 30,000 in number-averaged molecular weight and 12 nylon of 1,000 to 10,000 in number-averaged molecular weight, and the polyamide resin mixture has a 165 to 178°C fusion point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resin-bonded magnet composition and a resin-bonded magnet, and more particularly to a resin-bonded magnet composition having high melt flowability and good moldability and a resin-bonded magnet excellent in mechanical strength.

  In recent years, ferrite magnets, alnico magnets, rare earth magnets, and the like have been used for various applications including motors. However, since these magnets are mainly produced by a sintering method, they are generally brittle and it is difficult to obtain thin or complicated shapes. Further, since the shrinkage during sintering is as large as 15 to 20%, a product with high dimensional accuracy cannot be obtained, and there is a disadvantage that post-processing such as polishing is required to increase the accuracy.

  Resin-bonded magnets solve these drawbacks and open up new uses. Using a magnet composition filled with magnetic powder in a thermoplastic resin such as polyamide resin (nylon) as a binder. , Molded and magnetized.

  Resin-bonded magnets that use a thermoplastic resin as a binder, when the magnetic composition is filled with 80% by weight or more of magnetic powder, the viscosity at the time of melt molding suddenly increases and molding becomes difficult. Therefore, in order to maintain the moldability, molding is performed by adding a lubricant for thermoplastic resin such as stearic acid metal soap and paraffins. However, the addition of such a molding lubricant causes a significant decrease in mechanical strength, so that there is a problem that it is difficult to add a sufficient amount to ensure moldability. In particular, the tendency becomes stronger as the filling amount of the magnetic powder is increased in order to improve the magnetic properties, and these improvements are strongly desired.

  In addition, resin-bonded magnets used in recent small motors, acoustic devices, OA devices, and the like are required to have high magnetic characteristics, excellent dimensional accuracy, and low price due to the demand for miniaturization of devices. However, the moldability (melt flow characteristics) and mechanical strength of the conventional resin-bonded magnet composition obtained only with magnetic powder, polyamide resin and molding lubricant are always insufficient for use in the above-mentioned applications, An early improvement to a composition in which the moldability and the mechanical strength of the resin-bonded magnet composition are balanced has been desired.

  The present inventors have proposed to use a mixture of copolymer nylon and 12 nylon as a polyamide resin as a binder (see Patent Document 1). According to this, it becomes possible to produce a resin-bonded magnet having excellent magnetic properties, molding processability, and physical properties (particularly mechanical strength), but it is necessary to increase the molding temperature to 240 to 290 ° C. In addition, the deterioration of the magnetic properties due to the hysteresis temperature of the magnetic powder becomes large, and the moldability was not sufficient. Moreover, the mechanical strength of the magnet obtained by using this could not sufficiently meet the increasing market demand.

As a resin binder, it has been proposed to combine any of a copolyamide, a polyamide-based elastomer, and a polyester-based elastomer with respect to a single polyamide resin (see Patent Document 2). This is intended not only to lower the melt viscosity of the compound but also to set the solidification rate within a specific range because the solidification rate of the once melted compound is important. However, the balance between moldability and mechanical strength of the obtained composition was never sufficient, and it was not a performance balance that could fully meet market demands.
JP-A-8-236330 JP 2001-85209 A

  The object of the present invention is to eliminate the drawbacks of the conventional resin-bonded magnet composition using a polyamide resin-based resin binder, and to provide a resin-bonded magnet composition having high melt flowability and good moldability, and mechanical strength. It is to provide a resin-bonded magnet excellent in the above.

  In order to achieve the above object, the present inventors have made various polyamides as resin binders in a resin-bonded magnet composition comprising a magnetic powder having a large anisotropic magnetic field (HA) and a polyamide resin as a resin binder. As a result of examining various kinds of resins by changing the type and mixing amount of the resin, it is a mixture of 6/12 copolymer nylon having a specific number average molecular weight and 12 nylon, and the melting point is within a specific range. By using a certain polyamide resin, it was found that a resin-bonded magnet composition having excellent moldability (melt flowability) can be obtained, and a resin-bonded magnet excellent in mechanical strength can be produced, and the present invention was completed. It came to do.

  That is, according to the first aspect of the present invention, in the resin-bonded magnet composition in which the rare earth-transition metal magnetic powder (A) is mixed and dispersed in the resin binder (B), the resin binder (B) is A polyamide resin mixture of 6/12 copolymer nylon having a number average molecular weight of 10,000 to 30,000 and 12 nylon having a number average molecular weight of 1,000 to 10,000, and A resin-bonded magnet composition having a melting point of 165 to 178 ° C. is provided.

  According to the second invention of the present invention, in the first invention, the magnetic powder (A) is a rare earth-transition metal magnetism having an anisotropic magnetic field (HA) of 4.0 MA / m (50 kOe) or more. Provided is a composition for a resin-bonded magnet, which is a powder.

  According to the third invention of the present invention, in the first or second invention, the magnetic powder (A) contains a rare earth (Nd or Sm) and a transition metal (Fe and / or Co). A resin-bonded magnet composition is provided.

  According to the fourth invention of the present invention, in the first invention, the 6/12 copolymer nylon has a copolymerization ratio (a) :( b) of 6 component (a) and 12 component (b). The composition for resin-bonded magnets is characterized by being 10:90 to 50:50.

  According to the fifth invention of the present invention, in the first or fourth invention, the 6/12 copolymer nylon contains ω-laurolactam or 12-aminododecanoic acid as a lubricant component in an amount of 0.01 to 1.0. A composition for resin-bonded magnets is provided, which is characterized by comprising wt%.

  According to a sixth invention of the present invention, in the first invention, the 12 nylon contains 50% by volume or more of a modified 12 nylon whose both ends are carboxyl groups. Things are provided.

  According to a seventh aspect of the present invention, in the first aspect, the resin binder (B) is a resin characterized in that the blending amount is 1 to 20 parts by weight with respect to 100 parts by weight of the composition. A combined magnet composition is provided.

  Furthermore, according to an eighth invention of the present invention, in the first invention, the resin binder (B) contains 20 to 95% by weight of 6/12 copolymer nylon, and the composition for a resin-bonded magnet Things are provided.

  On the other hand, according to the ninth invention of the present invention, there is provided a resin-bonded magnet obtained by heat-molding the resin-bonded magnet composition of any one of the first to eighth inventions.

  The resin composition for resin-bonded magnets of the present invention is a resin-bonded magnet composition comprising a magnetic powder having a large anisotropic magnetic field (HA) and a polyamide resin-based resin binder, wherein the polyamide resin is 6 / It consists of a mixture of 12 copolymer nylon and 12 nylon, and their number average molecular weight and melting point are in a specific range, so it has excellent moldability (melt flowability), and the resin bond obtained using this The mold magnet has excellent mechanical strength. Therefore, the moldability and mechanical strength are improved as compared with the conventional one, and it is particularly useful in a wide range of applications such as general household appliances, communication / audio equipment, medical equipment, and general industrial equipment. .

  Hereinafter, the resin-bonded magnet composition and the resin-bonded magnet of the present invention will be described in detail.

  In the resin-bonded magnet composition of the present invention, the resin-bonded magnet composition in which the rare earth-transition metal magnetic powder (A) is mixed and dispersed in the resin binder (B), the resin binder (B) is: It is a composition comprising a polyamide resin mixture of 6/12 copolymer nylon and 12 nylon having a number average molecular weight within a specific range, and the polyamide resin mixture having a melting point within a specific temperature range.

1. Magnetic powder As the magnetic powder (A), a magnetic powder conventionally used in a resin-bonded magnet can be used. In the present invention, a rare earth-transition metal magnetic powder containing a rare earth element and a transition metal element is used. Is used. If the anisotropic magnetic field (HA) is 4.0 MA / m (50 kOe) or more of the magnetic powder, the magnetic powder usually used for the resin-bonded magnet is effective.

The rare earth elements include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy). , Holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
On the other hand, examples of the transition metal element include iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn), and one or more kinds are selected from each of these groups. In addition to this, in transition metal element, you may contain either Cr, V, or Cu.
A particularly preferred rare earth element is either Nd or Sm, and a transition metal element is either Fe or Co.

  Examples of the rare earth-transition metal magnetic powder include rare earth-cobalt, rare earth-iron-boron, rare earth-iron-nitrogen magnetic powder, and the like. Among these, those containing 5 to 40 atomic% of Sm or Nd and 50 to 90 atomic% of Fe and / or Co are particularly preferable.

The alloy powder of SmCo ₅ which is a rare earth-cobalt magnetic powder is an alloy composed of rare earth metal Sm and cobalt Co represented by the general formula of Sm _X Co _100-X , and the rare earth metal Sm amount x is 15 It is in the range of ˜20 atomic%, and the balance is mainly Co. Here, the Sm is defined as 15 to 20 atomic%. If the atomic ratio is less than 15 atomic%, the Sm ₂ Co ₁₇ phase is precipitated and the coercive force decreases, and the practical magnet is not used. This is because the Sm rich phase is precipitated, the alloy powder becomes unstable in the atmosphere, and the residual magnetization is lowered.

  As the Nd—Fe—B alloy powder, which is a rare earth-iron-boron magnetic powder, for example, an isotropic powder obtained by a rapid quenching method or an anisotropic powder obtained by an HDDR method is used. be able to. For example, the formation of a ribbon-like material by the liquid quenching method is performed by melting the alloy having the above-described composition by means such as high-frequency induction, and then rapidly cooling the molten metal by spraying it on a copper or aluminum roll that rotates at high speed. . The ribbon-like material can be pulverized by dry or wet pulverization using a stamp mill, a ball mill, or the like. Further, it is desirable to heat-treat the ribbon prior to pulverization, and this heat-treatment suppresses the growth of crystal grains, for example, the average crystal grain size becomes 300 nm or less.

An Sm—Fe—N alloy powder, which is a rare earth-iron-nitrogen based magnetic powder, is a nitridation composed of rare earth metal Sm, iron Fe, and nitrogen N represented by the general formula of Sm _x Fe _100-xy N _y. The rare earth metal Sm content (x) is in the range of 8.1 to 10 atomic%, the N content (y) is in the range of 13.5 to 13.9 atomic%, and the balance is mainly Fe. The Here, the Sm is defined as 8.1 to 10 atomic% when the content is less than 8.1 atomic%, the α-Fe phase is separated and the coercive force of the nitride is lowered, and the magnet is not a practical magnet. If it exceeds 10 atomic%, Sm precipitates, the alloy powder becomes unstable in the atmosphere, and the residual magnetization decreases. On the other hand, nitrogen N is defined to be in the range of 13.5 to 13.9 atomic%. If it is less than 13.5 atomic%, almost no coercive force is exhibited, and if it exceeds 13.9 atomic%, Sm, iron and This is because a nitride of the alkali metal itself is generated.

The Sm—Co ₅ or Sm—Fe—N magnetic powder obtained by the reduction diffusion method is preferably pulverized by a jet mill or a ball mill. The preferred particle size of these magnetic powders is 7 μm or less on average, particularly preferably 5 μm or less on average from the viewpoint of the melt fluidity of the magnet composition, the orientation of the magnetic powder, the filling rate, and the like.

If the above Sm—Co ₅ alloy powder, Sm—Fe—N alloy powder, or Nd—Fe—B alloy powder is used, for example, a high filling of 93% by weight or more is possible, and particularly excellent. A resin-bonded magnet having magnetic characteristics can be obtained. When the magnetic powder is filled in an amount of more than 95% by weight, the kneading torque and fluidity may be remarkably lowered and molding may be difficult. When the amount is less than 80% by weight, desired magnetic properties cannot be obtained. Therefore, the filling amount of the magnetic powder is preferably 80% by weight or more and 95% by weight or less.

  In the present invention, one or more types of magnetic powders of ferrite powders such as Sr ferrite and Ba ferrite and metal magnetic powders such as alnico, iron, chromium and cobalt are used in accordance with the required magnetic properties. A powder mixed with the powder can be used.

  Moreover, the said magnetic powder is used in the range of 0.1 to 3.0 weight% with respect to magnetic powder for a silane type | system | group, titanium type | system | group, aluminum type surface treating agent, ie, a coupling agent, etc. as needed. I can do it.

  Examples of these coupling agents include vinyltriethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) as silanes. ) -Γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, etc. In addition, titanium-based isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate , Tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate Over preparative like, also, acetoalkoxyaluminum diisopropylate, and the like as a typical as aluminum-based.

  In addition, by forming a thin silica film or organic silica film on the surface of the magnetic powder, it has also been confirmed that it contributes to improving the fluidity and mechanical strength of the resin-bonded magnet composition. These processes can also be performed.

2. Resin Binder The resin binder (B) used in the present invention serves as a binder for magnetic powder, which is an essential component, in the resin-bonded magnet composition, and is made of at least a two-component polyamide resin.

  The polyamide resin used in the present invention is a mixture of 6/12 copolymer nylon (B-1) and 12 nylon (B-2) each having a specific number average molecular weight, and the melting point is within a specific range. It is necessary to be.

(B-1) 6/12 copolymer nylon In the present invention, the 6/12 copolymer nylon needs to have a number average molecular weight of 10,000 to 30,000. A preferred number average molecular weight is 12,000 to 24,000. Further, those having a number average molecular weight of 13,000 to 18,000 are particularly preferred.

  If the number average molecular weight of the 6/12 copolymer nylon is less than 10,000, even if the number average molecular weight and mixing ratio of 12 nylon as the second component are changed within the scope of the present invention, the high temperature and high The phenomenon that the resin component and the magnetic powder separate due to the decrease in viscosity caused by significant melting in the shear region is likely to occur. On the other hand, when the viscosity is higher than 30,000, the viscosity increases and the melt flowability of the composition becomes remarkable. This is not preferable because the effect of the present invention cannot be obtained.

  6/12 copolymer nylon is a polycondensate of 6 component (a) caprolactam (hexamethylenediamine) and 12 component (b) lauryl lactam (12-dodecanactam) or 12-aminododecanoic acid. is there.

  The copolymerization ratio (a) :( b) needs to be 10:90 to 50:50. Preferably, the copolymerization ratio (a) :( b) is 10:90 to 30:70, more preferably 20:80 to 30:70. Here, when 6 component (a) is smaller than 10 and 12 component (b) is larger than 90, desired mechanical strength cannot be obtained. If the 6 component (a) exceeds 50 and the 12 component (b) is less than 50, the melting point increases depending on the amount of the 6 component (a), deviates from a desired value, and the viscosity becomes high. This is not preferable because the melt fluidity is remarkably lowered and the effects of the present invention cannot be obtained.

  Further, the 6/12 copolymer nylon preferably contains 0.01 to 1.0% by weight of ω-laurolactam or 12-aminododecanoic acid as a lubricant component. If the amount of these lubricant components is less than 0.01% by weight, the effect of increasing the mechanical strength does not appear, and the effect increases as the amount added increases. However, since mechanical strength will fall when it exceeds 1.0 weight%, 0.02 to 0.5 weight% is preferable.

(B-2) 12 nylon 12 nylon, which is the second component of the resin binder, is a polyamide represented by the general formula of — (NH— (CH ₂ ) ₁₁ —CO) n—.

  In the present invention, 12 nylon must have a number average molecular weight in the range of 1,000 to 10,000. In particular, the number average molecular weight is preferably 3,000 to 8,000. Furthermore, those having a number average molecular weight of 3,000 to 6,000 are particularly preferred.

  When the number average molecular weight of 12 nylon is less than 1,000, even if the number average molecular weight and mixing ratio of 6/12 copolymer nylon are changed within the scope of the present invention, the temperature is high during molding or in a high shear region. The viscosity is greatly reduced when melted, causing a phenomenon in which the resin component and the magnetic powder are separated. On the other hand, if it exceeds 10,000, the viscosity becomes high and the melt flowability of the composition is significantly lowered, so that the effect of the present invention cannot be obtained.

  Further, as the 12 nylon having a number average molecular weight of 1,000 to 10,000, terminal group-modified 12 nylon having both carboxyl groups is preferred. The amino group present at the end of 12 nylon can be modified with, for example, dicarboxylic acid to produce terminal-modified 12 nylon having a structure having carboxyl groups at both ends. It has been confirmed that the mechanical strength of the molded article is increased by including 50% by volume or more of the modified 12 nylon. When the amount of the modified 12 nylon is less than 50% by volume, the effect of increasing the mechanical strength of the molded product is reduced.

In the present invention, it is necessary to mix the 6/12 copolymer nylon (B-1) and 12 nylon (B-2) to form a polyamide resin mixture.
Although the mixing ratio of 6/12 copolymer nylon (B-1) and 12 nylon (B-2) is arbitrary, it is preferable that 6-12 copolymer nylon is included 20 to 95 weight%. A more preferable one contains 30 to 90% by weight, particularly preferably 40 to 80% by weight of 6/12 copolymer nylon. If the 6/12 copolymer nylon is less than 20% by weight, the desired mechanical strength cannot be obtained, and if it is more than 95% by weight, it deviates from the desired melting point and becomes low.

  These polyamide resin mixtures are required to have a melting point of 165 to 178 ° C. When the melting point is lower than 165 ° C., the heat distortion temperature of the molded product is lowered, which is not practical. On the other hand, when the temperature exceeds 178 ° C., the molding temperature is raised, and this causes an influence such as oxidation of a part of the magnetic powder, leading to a decrease in magnetic properties, which is not preferable.

By combining these limited conditions, the fluidity Q value can be increased to an unprecedented high value (for example, 0.1 cm ³ / second or more). As a result, the moldability is improved and the molding temperature is 210 to 210. By being lowered to 230 ° C., it is possible to obtain a resin-bonded magnet that can suppress the deterioration of magnetic properties and has excellent mechanical strength.

  As long as this condition is satisfied, end groups of other types, for example, 6 nylon, 66 nylon, 11 nylon, aromatic nylon, and the like, copolymers of these homopolymers and other types of monomers, and other substances. It can be mixed with processed products.

By the way, although patent document 1 discloses using a mixture of copolymer nylon and 12 nylon as a polyamide resin, their molecular weight is not described. The number average molecular weight of the 6/12 copolymer nylon used at that time was about 25,000, and the 12 nylon used at that time had a number average molecular weight of about 14,000.
However, as described above, in a mixture of these polyamide resins, the moldability cannot be improved and the molding temperature cannot be lowered to 210 to 230 ° C., resulting in deterioration of magnetic properties, resulting in a mechanical strength. An excellent resin-bonded magnet cannot be obtained.

On the other hand, in the polyamide resin mixture in which 6/12 copolymer nylon (B-1) and 12 nylon (B-2) of the present invention are mixed, the number average of 6/12 copolymer nylon is as described above. Even if the molecular weight is in the range of 10,000 to 30,000, the 12/12 nylon having a number average molecular weight in the range of 1,000 to 10,000 is combined. 12 nylon molecules with a small molecular weight can easily enter, the density of the mixed resin itself is improved, and the mechanical strength of the resin is improved, so that the mechanical strength of the bond magnet using this is improved. ing.
This tendency is more prominent when 12 nylons having a number average molecular weight of 6/12 copolymer nylon of 13,000 to 18,000 and a number average molecular weight of 3,000 to 6,000 are combined. It will be a thing.

The resin binder of the present invention includes, in addition to polyamide resins, polyolefin resins such as polyethylene and polypropylene, polystyrene resins, polyvinyl resins, acrylic resins, acrylonitrile resins, polyurethane resins, as long as the object of the present invention is not impaired. Polyether resins, fluorine resins, polyphenylene sulfide resins, vinyl chloride resins, polycarbonate resins, polysulfone resins, vinyl acetate resins, ABS resins, acrylic resins, polyether ether ketones, and the like can be used.
However, 50% by weight or more of these thermoplastic resins cannot be blended with the resin binder of the present invention. If 50% by weight or more is blended, both the elongation at break and magnetic properties are lowered, and flexibility under a low temperature environment cannot be improved, which is not preferable.

3. Method for Producing Resin-Bonded Magnet Composition The composition for a resin-bonded magnet according to the present invention is (1) after preparing the above magnetic powder, surface-treating with a phosphoric acid compound if necessary, and further coating with a coupling agent (2) It is manufactured by mixing a resin binder and dispersing magnetic powder.

(1) Treatment with phosphoric acid compound and coupling agent In the present invention, the magnetic powder can be surface treated with a phosphoric acid compound, if necessary. A metal compound such as Zn may be used instead of the phosphoric acid compound. In addition, the magnetic powder coated with phosphate can be further coated with a coupling agent.

  In the present invention, the magnetic powder can be subjected to a surface treatment using at least one of a silane coupling agent, an aluminum coupling agent, a titanate coupling agent, and a zirconate coupling agent. By covering the surface of the magnetic powder by this surface treatment, the melt fluidity at the time of high filling can be improved more effectively.

  The coupling agent is coated on the magnetic powder by either a wet processing method or a dry processing method, and is then fixed to the magnetic powder more stably by heating and drying. That is, the coupling agent solution and the magnetic powder are sufficiently mixed and stirred (for example, 40 rpm, 20 ° C., holding / stirring time 20 minutes) by a planetary mixer, and finally 10 in a vacuum oven at 100 to 150 ° C. Allow to dry for ~ 30 hours.

  The amount of the coupling agent added varies depending on the type and concentration, but is generally preferably 0.1 to 3.0% by weight, more preferably 0.1 to 2.0% by weight, based on the magnetic powder. . If the amount is less than 0.1% by weight, sufficient melt fluidity improvement and environmental resistance improvement effects cannot be obtained. If the amount exceeds 3.0% by weight, the density of the molded product decreases, and the resin-bonded type The mechanical strength of the magnet is reduced and desired magnetic properties cannot be obtained.

  As the surface treatment method of the present invention, if necessary, a surface treatment step with a phosphoric acid compound is provided to coat the magnetic powder, and then the magnetic powder is treated with a coupling agent, and then mixed with a resin binder. Although preferable, the magnetic powder, the resin binder, and the coupling agent may be mixed together. However, in order to obtain a more reliable surface-treated film, it is desirable to mix with a resin binder after treating with a coupling agent when pulverizing the magnetic powder.

(2) Dispersion of magnetic powder in resin binder Next, the surface-treated magnetic powder is mixed and dispersed in the resin binder. The shape of the polyamide resin mixture, which is a resin binder, is not particularly limited, such as powder, beads, pellets, etc., but powder is desirable in view of uniform mixing with magnetic powder.

  The blending amount of the resin binder (B) is not particularly limited, and may be appropriately selected according to the molding method at a ratio of 1 to 20 parts by weight with respect to 100 parts by weight of the composition. In particular, the resin binder (B) is preferably mixed at a ratio of 1 to 15 parts by weight. When the amount of the resin binder (B) is less than 1 part by weight, the magnetic properties are insufficient, and when the amount is more than 20 parts by weight, the moldability deteriorates, which is not preferable.

  In the present invention, a remarkable effect is obtained when the magnetic powder is highly filled as described above. However, the resin-bonded magnet composition of the present invention contains less than 80 parts by weight of the magnetic powder. Even in this case, it is advantageous in terms of the uniform dispersibility of the magnetic powder.

  When obtaining the resin-bonded magnet composition of the present invention, if necessary, after blending the following additives and fillers, the resin-bonded magnet composition may be melt-kneaded. For example, a Banbury mixer , Kneaders, rolls, kneader ruders, single-screw extruders, twin-screw extruders and the like.

  The resin-bonded magnet composition of the present invention is composed of the above magnetic powder and resin binder as essential components. In addition to these, a molding lubricant (C) different from the above-mentioned lubricant component as an additive. If a stabilizer or stabilizer (D) is used, the heat fluidity of the composition is further improved and the moldability and magnetic properties are improved.

(C) Molding lubricants Molding lubricants include, for example, paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, microwax and other waxes, stearic acid, 1,2-oxystearic acid, lauric acid , Fatty acids such as palmitic acid and oleic acid, calcium stearate, barium stearate, magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate, zinc 2-ethylhexoate Fatty acid salts (metal soaps) such as stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, lauric acid amide, hydroxystearic acid amide , Fatty acid amides such as methylene bis stearamide, ethylene bis stearamide, ethylene bis laurate amide, distearyl adipate amide, ethylene bis oleate amide, dioleyl adipate amide, N-stearyl stearate amide, stearic acid Fatty acid esters such as butyl, alcohols such as ethylene glycol and stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethers composed of these modified products, polysiloxanes such as dimethylpolysiloxane and silicon grease, fluorine Inorganic compounds such as fluorine compounds, silicon nitride, silicon carbide, magnesium oxide, alumina, silicon dioxide, molybdenum disulfide such as fluorine oil, fluorine grease, and fluorine-containing resin powder Body, and the like.

(D) Stabilizer As the stabilizer, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate , 1- [2- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,2,3-triazaspiro [4,5] undecane -2,4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetrasuccinate Methyl piperi Gin polycondensate, poly [[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetra Methyl-4-piperidyl) imino] hexamethylene [[2,2,6,6-tetramethyl-4-piperidyl) imino]], 2- (3,5-di-tert-butyl-4-hydroxybenzyl)- In addition to hindered amine stabilizers such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) 2-n-butylmalonate, antioxidants such as phenols, phosphites and thioethers Etc.

  The amount of these additives is appropriately selected according to the type of the resin binder and the type of magnetic powder, and is not particularly limited, but is usually 100 parts by weight of the resin-bound magnet composition, It is preferable to set it as 0.1-10 weight part, especially 0.1-3 weight part.

Furthermore, a filler having a large reinforcing effect such as mica, whisker, talc, carbon fiber, or glass fiber can be appropriately added to the resin-bonded magnet composition of the present invention as long as the object of the present invention is not hindered. . That is, if the magnetic properties required for the resin-bonded magnet are relatively low and the amount of the magnetic powder is relatively small, the mechanical strength of the resin-bonded magnet tends to be low. In order to supplement the mechanical strength, a filler such as mica or whisker can be added to supplement the mechanical strength of the resin-bonded magnet.
The type and blending amount of these fillers are not particularly limited, and may be appropriately selected according to the required characteristics of the resin-bonded magnet.

  The composition for a resin-bonded magnet of the present invention is added to a total amount of magnetic powder so that a predetermined resin and each additive system are added in a predetermined ratio, sufficiently mixed and stirred in the mixer, and dried in a vacuum oven. Let The above mixture can be obtained in the form of powder, beads, pellets or a mixture thereof. Pellets are desirable because they can be stably supplied from an inclined hopper to the molding machine.

  In the present invention, the mixing method of each component is not particularly limited. For example, a mixer such as a ribbon blender, a tumbler, a nauter mixer, a Henschel mixer, a super mixer, or a banbury mixer, a kneader, a roll, a kneader ruder, a single screw extruder. It is carried out using a kneader such as a twin screw extruder. The melting temperature of the resin-bonded magnet composition of the present invention is 165 to 178 ° C., and is kneaded at a temperature higher than the melting temperature.

4). Resin-bonded magnet The resin-bonded magnet composition obtained in this way is not only magnetic properties and shape flexibility by being heat-molded by injection molding, compression molding, extrusion molding, rolling molding, transfer molding, etc. The resin-bonded magnet of the present invention having excellent rust resistance, mechanical strength, flexibility, heat resistance and the like can be obtained. In particular, the resin-bonded magnet of the present invention has a mechanical strength of 80 MPa or more, and can easily be obtained with a strength of 100 MPa or more.
Various types of thermoplastic resin molding machines, preferably injection molding machines and extrusion molding machines can be used for thermoforming the resin-bonded magnet composition.

Since the resin-bonded magnet composition of the present invention is excellent in melt fluidity, it is most effective to be used for injection molding that requires high magnetic properties and high mechanical strength.
In the case of injection molding, the resin-bonded magnet composition is thermoformed under the condition that the maximum history temperature is 300 ° C. or lower, preferably 260 ° C. or lower. When the maximum history temperature exceeds 300 ° C., there is a problem in that the magnetic characteristics are deteriorated, which is not preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, although the detail of each component used for the Example and the comparative example, the test method, and evaluation are illustrated, unless it deviates from the meaning of this invention, it is not limited to these.

The materials used as raw materials for the resin-bonded magnet composition (magnet) are shown below.
A Magnetic powder ・ Magnetic powder 1: SmFeN magnetic powder
(Product name: SmFeN alloy, manufactured by Sumitomo Metal Mining Co., Ltd.)
Anisotropic magnetic field: 19.6 MA / m (246 kOe)
・ Magnetic powder 2: Nd-Fe-B magnetic powder
(Product name: MQP-B, manufactured by General Motors, USA)
Anisotropic magnetic field: 5.6 MA / m (70.4 kOe)

B Polyamide resin ・ PA1
6/12 copolymer nylon (number average molecular weight Mn = 14,000,
Copolymerization ratio of 6 component (a) and 12 component (b) (a) :( b) = 25: 75)
・ PA2
6/12 copolymer nylon (number average molecular weight Mn = 24,000,
Copolymerization ratio (a) :( b) = 50: 50)
・ PA3
6/12 copolymer nylon (number average molecular weight Mn = 35,000,
Copolymerization ratio (a) :( b) = 25: 75)
・ PA4
6/12 copolymer nylon (number average molecular weight Mn = 8,000,
Copolymerization ratio (a) :( b) = 25: 75)
・ PA5
12 nylon (number average molecular weight Mn = 8,000, no modification at both ends)
・ PA6
Modified 12 nylon (number average molecular weight Mn = 5,000,
Both terminal carboxyl groups)
・ PA7
12 nylon (number average molecular weight Mn = 14,000, no modification at both ends)

C. Lubricant component. ω-Laurolactam (Kanto Chemical Co., Ltd.)
. 12-aminododecanoic acid (manufactured by Kanto Chemical Co., Inc.)

Next, evaluation methods for each composition and molded product obtained using the above raw materials will be described.
(1) Melt fluidity evaluation method The pellet-like composition obtained by kneading the magnetic powder and the resin binder was subjected to a temperature of 250 ° C. and a load of 294.2 N using an elevated flow tester manufactured by Shimadzu Corporation. The fluidity (Q value) was measured under the conditions of (30 kgf), die shape: 1 mmφ × 1 mm, preheating: 120 seconds.
It has been found that if a fluidity of 0.05 cm ³ / sec or more can be secured by the fluidity evaluation, no problem is caused in molding.

(2) Evaluation of mechanical strength (three-point bending strength) Using the above pellet compound in a magnetic field injection molding machine (manufactured by Nippon Steel Works, J-20MII), for a test of 5 mm wide × 15 mm long × 2 mm thick The resin-bonded magnet was molded under the same conditions (molding temperature 210 to 270 ° C. (in the example, 210 to 230 ° C.), mold temperature 100 to 120 ° C.). The bending strength of the obtained magnet molded product was determined at room temperature using a Shimadzu Corporation autograph with a head speed of 2 mm / min.
It is known that if the bending strength is 80 MPa or more, the mechanical strength as a molded product is sufficient.

(Examples 1-4)
To 100 parts by weight of magnetic powder 1, add a resin binder containing a predetermined amount of polyamide resin (PA1 and PA5) to a predetermined ratio, mix and stir well in a planetary mixer (40 rpm, 80 ° C.), and again The film was dried in a vacuum oven at 120 ° C. for 24 hours with a degree of vacuum of about 1 Pa.
The mixture obtained by these operations was converted into a 20 mmφ single extruder (screw length / diameter ratio L / D = 25, compression ratio CR = 2.0, rotation speed = 20 rpm, 5 mmφ strand die, cylinder temperature 200 ° C. to 230 ° C. Extrusion was performed at a die temperature of 210 to 230 ° C. (210 ° C. in the example), and a pellet compound for a resin-bonded magnet having a diameter of 5 mm × 5 mm was produced by a hot cut pelletizer.
Further, the melting point of the polyamide resin mixed without adding magnetic powder was separately measured using DSC3100S manufactured by Mac Science Co., Ltd. The results are shown in Table 1.

(Example 5)
An experiment was conducted in the same manner as in Example 2 except that magnetic powder 2 was used instead of magnetic powder 1. The results are shown in Table 1.

(Examples 6 to 9)
The experiment was performed in the same manner as in Example 1 except that the ratio of PA1 and PA2 of the resin binder was changed. Moreover, it experimented like the said Example 2 except having replaced a part of PA5 of resin binder with PA6. Furthermore, when PA2 and PA6 were used as the resin binder, the experiment was performed in the same manner as in Example 2 except that part of the resin binder PA1 was replaced with PA2. The results are shown in Table 2.

(Examples 10 to 12)
The experiment was performed in the same manner as in Example 2 except that PA1 of the resin binder was replaced with PA2. Moreover, it experimented like the said Example 2 except having replaced PA5 of the resin binder with PA6. Furthermore, it experimented similarly using PA1, PA2, PA5, and PA6 as a resin binder. The results are shown in Table 3.

(Examples 13 to 15)
The experiment was conducted in the same manner as in Example 2 except that ω-laurolactam or 12-aminododecanoic acid was contained in PA1 of the resin binder. The results are shown in Table 3.

(Comparative Examples 1-3)
Either PA1, PA5, or PA7 is used alone as a resin binder, added to magnetic powder 1, sufficiently mixed and stirred (40 rpm, 80 ° C.) in a planetary mixer, and the degree of vacuum is about 1 Pa, 120 ° C. again. For 24 hours in a vacuum oven.
The mixture obtained by these operations was converted into a 20 mmφ single extruder (screw length / diameter ratio L / D = 25, compression ratio CR = 2.0, rotation speed = 20 rpm, 5 mmφ strand die, cylinder temperature 200 ° C. to 230 ° C. Then, extrusion was performed at a die temperature of 210 to 230 ° C., and a pellet compound for a resin-bonded magnet having a diameter of 5 mmφ × 5 mm was produced with a hot cut pelletizer.
Further, the melting point of the polyamide resin mixed without adding magnetic powder was separately measured using DSC3100S manufactured by Mac Science Co., Ltd. The results are shown in Table 4.

(Comparative Examples 4-5)
The experiment was conducted in the same manner as in Example 2 except that PA7 as the resin binder was replaced with PA7. Moreover, it experimented like the said Example 2 except having replaced PA1 of the resin binder with PA7. The results are shown in Table 4.

(Comparative Examples 6-11)
Experiments were conducted when either PA3 or PA4 was used alone as the resin binder. Further, when the resin binders PA3 and PA5 were combined, and when the resin binders PA4 and PA5 were combined, the same experiment was conducted. The results are shown in Table 5.

Examples 1 to 14 use 6/12 copolymer nylon and 12 nylon whose number average molecular weight is in the range of the present invention, and the melting point of the mixed resin is in the range of 165 to 178 ° C. It shows that the quality Q value and the mechanical strength can be obtained.
That is, from Examples 1 to 4 and 6, when 12 nylon (PA5) having a number average molecular weight within the range of the present invention and 6/12 copolymer nylon (PA1) are used in combination, 12 to 6/12 copolymer nylon is used. As the proportion of nylon increases, the fluidity Q value tends to increase. As in Examples 7 to 12, it can be seen that even when various resins are mixed, the effect does not change and desired good characteristics can be obtained.
Further, Examples 13 to 15 show that when ω-laurolactam or 12-aminododecanoic acid is added to the composition of Example 2, the mechanical strength is increased.
Therefore, in order to obtain a composition and a molded article excellent in moldability and mechanical strength, 6/12 copolymer nylon and 12 nylon whose number average molecular weight is limited within the scope of the present invention are used, and the melting point is 165. It can be seen that the temperature must be not lower than 178 ° C. and not higher than 178 ° C., and both must be blended in a balanced manner.

On the other hand, in Comparative Examples 1 and 2, either 6/12 copolymer nylon or 12 nylon is used, and both are not used in combination. Therefore, even if the fluidity Q value is lowered, molding is possible by raising the molding temperature, but the mechanical strength of the obtained molded product is extremely low and cannot be measured, or the fluidity Q value is Although it becomes high, it turns out that the mechanical strength of the obtained molded product will become very low.
Further, since Comparative Example 3 uses 12 nylon (PA7) whose number average molecular weight deviates from the scope of the present invention, it is found that the fluidity Q value and mechanical strength do not reach the desired values. The
Further, from Comparative Example 4, even if 6/12 copolymer nylon (PA1) whose number average molecular weight is in the range of the present invention is combined with 12 nylon whose upper limit of the number average molecular weight deviates from the range of the present invention, It can be seen that the desired fluidity Q value and mechanical strength cannot be obtained.
Even if 12 nylon having a number average molecular weight within the range of the present invention is used from Comparative Example 5, when combined with 12 nylon whose upper limit of the number average molecular weight deviates from the range of the present invention, the desired fluidity Q value and machine It can be seen that it is not possible to gain strength.
In Comparative Examples 6 to 8, 6/12 copolymer nylon (PA3) whose upper limit of the number average molecular weight deviated from the scope of the present invention was used alone, or 12 nylon (number average molecular weight within the scope of the present invention) It can be seen that when PA5) is substituted and the amount of 12 nylon (PA5) is small, the composition is difficult to mold. By increasing the amount of 12 nylon (PA5), the fluidity Q value can be measured and can be molded, but it does not reach the desired value. Therefore, it can be seen that there is a preferred range for the number average molecular weight of the 6/12 copolymer nylon.
In Comparative Examples 9 to 11, 6/12 copolymer nylon (PA3) whose lower limit of the number average molecular weight deviated from the scope of the present invention was used alone, or 12 nylon (number average molecular weight within the scope of the present invention) When PA5) is combined, if the amount of 12 nylon (PA5) is small, the composition becomes difficult to mold. By increasing the amount of 12 nylon (PA5), the fluidity Q value becomes a desired value and molding is performed. It can be seen that the mechanical strength does not reach the desired value. Thereby, it turns out that there exists a preferable range in the number average molecular weight of 6/12 copolymer nylon.

Claims (9)

In the resin-bonded magnet composition in which the rare earth-transition metal magnetic powder (A) is mixed and dispersed in the resin binder (B),
The resin binder (B) is composed of a polyamide resin mixture of 6/12 copolymer nylon having a number average molecular weight of 10,000 to 30,000 and 12 nylon having a number average molecular weight of 1,000 to 10,000, and A melting point of the polyamide resin mixture is 165 to 178 ° C.   The magnetic powder (A) is a rare earth-transition metal magnetic powder having an anisotropic magnetic field (HA) of 4.0 MA / m (50 kOe) or more, for a resin-bonded magnet according to claim 1. Composition.   3. The resin-bonded magnet composition according to claim 1 or 2, wherein the magnetic powder (A) contains a rare earth (Nd or Sm) and a transition metal (Fe and / or Co).   The 6/12 copolymer nylon has a copolymerization ratio (a) :( b) of 6 component (a) and 12 component (b) of 10:90 to 50:50. The composition for resin-bonded magnets as described.   The resin-bonded magnet according to claim 1 or 4, wherein the 6/12 copolymer nylon contains ω-laurolactam or 12-aminododecanoic acid as a lubricant component in an amount of 0.01 to 1.0% by weight. Composition.   12. The resin-bonded magnet composition according to claim 1, wherein the 12 nylon contains 50% by volume or more of a modified 12 nylon having both carboxyl groups at both ends.   2. The resin-bound magnet composition according to claim 1, wherein the amount of the resin binder (B) is 1 to 20 parts by weight with respect to 100 parts by weight of the composition.   The resin binder magnet composition according to claim 1, wherein the resin binder (B) contains 20 to 95% by weight of 6/12 copolymer nylon.   A resin-bonded magnet obtained by thermoforming the resin-bonded magnet composition according to claim 1.