Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/10—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
  • H01F1/11—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles
  • H01F1/113—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles in a bonding agent
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
  • H01F1/047—Alloys characterised by their composition
  • H01F1/053—Alloys characterised by their composition containing rare earth metals
  • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
  • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
  • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
  • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
  • H01F1/0578—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together bonded together
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
  • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
  • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
  • H01F1/083—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together in a bonding agent

Definitions

• This invention relates to compositions for the manufacture of magnets and magnets obtained by moulding said compositions. More particularly, it relates to bonded magnet moulding compositions with excellent magnetic properties, good mouldability and additionally superior heat stability during the moulding process, and the bonded magnets obtained therefrom.
• Bonded magnets made from compositions comprising organic polymer material consisting of thermoplastic resin and magnetic material are well known.
• bonded magnet moulding compositions of this kind products having a complex shape can be moulded by a plastic moulder such as an injection moulder, an extrusion moulder or a compression moulder without post-treatment, and this procedure is nowadays used for bonded magnet moulding in various applications.
• a plastic moulder such as an injection moulder, an extrusion moulder or a compression moulder without post-treatment
• this procedure is nowadays used for bonded magnet moulding in various applications.
• bonded magnets of very high performance because of the demand for downsizing and downweighting of electric products, auto-parts, etc. for electronic products, printers and others, it is highly desired to make bonded magnets of very high performance. In order to realize this aim, it is necessary to increase the content of the magnetic material while maintaining good mouldability.
• Japanese patent laid-open 1987-123702 describes a composition comprising magnetic powder surface-treated with a coupling agent and synthetic resin.
• Japanese patent laid-open 1988-181403 the use of copolymers is disclosed.
• Japanese patent laid-open 1990-65103 describes the use of additivesetc. to try to improve the magnetic property and to improve the mouldability such as flowability.
• the content of the magnetic material is 65 % or more in volume ratio (corresponding to around 93 % or more when expressed by weight, depending on the substance used), having both heat stability and flowability, and the ability to give a strong mechanical strength to the moulded article, while maintaining the desired magnetic properties.
• This invention offers a bonded magnet moulding composition which can be moulded particularly to a bonded magnet of thin thickness having high magnetic property by injection and/or extrusion moulding without deterioration of the flowability, the heat stability and the mechanical strength after the moulding, and also having improved magnetic properties resulting from a high density filling of the magnetic material.
• a hydrazine compound having a hindered phenolic structure may comprise a polyamide type resin and magnetic material particles, the content of the hydrazine derivative in the said composition being 0.3-2.0 weight%, preferably 0.7-1.5 weight%. It has also been found that an excellent bonded magnet moulding composition having high magnetic property can be obtained with the magnetic material incorporated at a high density of 65 % or more of the volume ratio.
• polyamide type resins which may be used in this invention, by adding 1-70 weight%, preferably 20-50 weight%, of polyamide copolymer to it, it has been found that a bonded magnet moulding composition having high magnetic property with further improved extrusion mouldability can be obtained.
• the mechanism of the flowability improvement resulting from the addition of the divalent phenolic hydrazine compound having a hindered phenolic group is not known for certain but, in addition to the oxidation resistant action of the divalent hydrazine derivative it is considered that a mechanochemical amide substitution reaction may occur under high temperature and high shear. As a result, the molecular weight of the matrix resin is lowered, the flowability of the composition is increased the mouldability is improved, and moreover the high density filling of the magnetic material can be realized and therefore the magnetic property can be enhanced.
• the copolymer has lower crystallinity and longer crystallization time than the polyamide homopolymer, so that the moulding composition takes a long time for solidification in a die when it is processed by injection moulding, and thus the flowability during the processing is improved.
• the solidification time at the exit of a die is long, and thus a pressure elevation at the edge of the die can be reduced and a load on the screw can also be lightened.
• Suitable examples of the polyamide type resin to be used in this invention are 6-nylon, 6,6-nylon, 12-nylon, but others may also be used.
• a suitable polyamide copolymer which may be used in this invention is a copolymer of different polyamide type resins such as 6-nylon and 12-nylon, 6-nylon and 6,6-nylon.
• the incorporated amount of the divalent phenolic hydrazine compound to be used in this invention may be 0.3-2.0 weight%. If the incorporation amount is less than about 0.3 the desired heat stability and mouldability are not attained. On the other hand, if it is more, the magnetic property may not be attained to the level required for many applications.
• Suitable examples of the divalent phenolic hydrazine compound having a sterically hindered hydroxyl group are IRGANOX MD1024 (Ciba-Geigy product) shown by the below-listed formula 1, or N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)alkanoyl]hydrazines shown by formula 2 and formula 3, in which X represents t-butyl.
• the magnetic material to be used in this invention can be magnetic or magnetizable material. Therefore the magnetic material does not need to be magnetized itself insofar as it can be magnetized by application of magnetic field during the production of the magnet or afterwards.
• the magnetic material ferrite materials such as barium ferrite (BaO.6Fe2O3) and strontium ferrite (SrO6Fe2O3) described in Japanese patent laid-open 1989-162301, intermetallic compounds of rare earth metals for the bonded magnet having high magnetic property (Sm, Ce, La, Y, Nd, Pr, Gd) with transition metals (Fe, Co, Ni, Zr,Hf, Cu, Ti), or intermetallic compounds comprising at least one of the rare earth metals and at least one of the transition metals based on neodymium-iron-boron, etc.
• the magnetic material comprising neodymium-iron-boron is particularly preferred for use according to this invention.
• a lubricant for the purposes of this invention, a lubricant, a lubrication oil, and other mould-processing auxiliaries can be added to the moulding compositions.
• a lubricant stearic acid, stearate, fatty acid amide and wax can be used and as for the lubricating oil, silicone oil can be used. It is preferable that these auxiliaries comprise 0.05-0.5 weight% of the mixture of the magnetic material and the matrix resin.
• raw material for the preparation of bonded magnet moulding of this invention for example, 6,6-nylon pellets on the market can also be used as the substrate of the matrix resin, but it is preferable to use material in powder form before pelletizing for evenness of mixing and kneading.
• GM product, MQ-P powder 93.4 weight% of neodymium-iron-boron powder (GM product, MQ-P powder), 5.5 weight% of 12-nylon powder (Ube Kosan product, P-3014U) and 1.0 weight% of a hydrazine compound (Ciba-Geigy product, IRGANOX MD-1024) were placed in a Henschell mixer (Mitsuimiike Kako Product, FM10B) and were mixed for 1 minute. Then 0.1 weight% of silicone oil (Bayer product, PN-200) was added to the mixture and they were again mixed for 1 minute.
• a Henschell mixer Mitsubishi Kako Product, FM10B
• the bonded magnet moulding composition obtained was kneaded at 250°C by using a labo-plastomill mixer (Toyoseiki Seisakusho product, 30C-150), it was measured by a torque elevation ratio, a value that a torque value after 10 minutes was divided by a torque value after 1 minute.
• the viscosity of the pellets was measured with shear rate of 1216 sec-1 at 250°C by using a capillary flow meter (Toyoseiki Seisakusho product, CAPIROGRAPH PM-C), and a bar flow was also evaluated by measuring a flow length with an injection pressure of 1400 kg/cm2 at 270°C by a bar flow die having a bar channel shape of 10 mm wide and 1 mm deep byusing an injection moulder (Toshiba product, EPN-80).
• the injection mouldability thereof was evaluated by ⁇ ⁇ and X with a cylindrical bonded magnet of 24 mm inside diameter, 26mm outside diameter and 4 mm length by using an injection moulder (Toshiba product, EPN-80).
• ⁇ was that it could be moulded by general moulding condition
• ⁇ was that it could somehow be moulded by a high temperature and a high injection pressure
• X was that a satisfactory moulding could not be achieved even by a high temperature and a high injection pressure.
• the magnetic property (BH)max of the cylindrical bonded magnet obtained was measured by a BH tracer.
• a bonded magnet moulding composition was prepared in the similar manner to the example 1 by using the composition shown in the table 1 as the example 2.
• a bonded magnet moulding composition was prepared in the similar manner to the example 1 by using the composition shown in the table 1 as the comparative example 1.
• a bonded magnet moulding composition was prepared in the similar manner to the example 1 by using the composition shown in the table 1 as the comparative example 2.
• a bonded magnet moulding composition was prepared in the similar manner to the example 1 by using the composition shown in the table 2 as the example 3.
• the bonded magnet moulding composition obtained as similar to the example 1, as the heat stability evaluation, it was measured by a torque elevation ratio, a value that a torque value after 10 minutes was divided by a torque value after 1 minute by using a labo-plastomill mixer (Toyoseiki Seisakusho product, 30C-150) by kneading at 250 °C. Additionally, the viscosity of the pellets was measured with shear rate of 1216 sec-1 at 250°C by using a capillary flow meter (Toyoseiki Seisakusho product, CAPIROGRAPH PM-C).
• a bonded magnet moulding composition was prepared in the similar manner to the example 1 by using the composition shown in the table 2 as the comparative example 3.
• a bonded magnet moulding composition was prepared in the similar manner to the example 1 by using the composition containing a polyamide copolymer shown in the table 3 as the example 4.
• the bonded magnet moulding composition obtained as similar to the example 1, as the heat stability evaluation, it was measured by a torque elevation ratio, a value that a torque value after 10 minutes was divided by a torque value after 1 minute by kneading at 250°C by using a labo-plastomill mixer (Toyoseiki Seisakusho product, 30C-150). Additionally, the viscosity of the pellets was measured with shear rate of 24.3 sec-1 at 210 °C by using a capillary flow meter (Toyoseiki Seisakusho product, CAPIROGRAPH PM-C).
• Bonded magnet moulding compositions were prepared in the similar manner to the example 1 by using the compositions containing the polyamide copolymer shown in the table 3 as the examples 5-7.
• Bonded magnet moulding compositions were prepared in the similar manner to the example 1 by using compositions shown in the table 3 as the comparative examples 4-5.
• Example 3 Comparative example 3 Composition (weight%) neodymium-iron-boron powder 93.9 93.9 12-nylon 5.0 5.6 hydrazine compound 4) 1.0 - silicone oil 0.1 0.5
• Property torque elevation ratio 1) 0.8 2.2 viscosity 2) (k poise) 9 15 extrusion mouldability 3) ⁇ X (BH)max (MGOe) 7.1 - (Remarks) 1), 2), 3) and 4) in the table 1 mean the following respectively 1) It means a value that a torque value after 10 minutes is divided by a torque value after 1 minute by kneading at 250°C by using a labo-plastomill mixer (Toyoseiki Seisakusho product, 30C-150).
• IRGANOX MD1024 (Ciba-Geigy product) [0042]
• the present invention thus provides a bonded magnet moulding composition with good mouldability having improved magnetic property by filling high density of the magnetic material, and having the ability to be moulded by injection moulding and extrusion moulding. Additionally, the magnets obtained do not show deterioration of mechanical strength after the moulding by either injection moulding or extrusion moulding and have the high performance magnetic property similar to those obtained by compression moulding.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Hard Magnetic Materials (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1991
  • 1991-10-18 JP JP3270884A patent/JPH05109516A/ja active Pending
• 1993
  • 1993-01-04 EP EP93300006A patent/EP0605934B1/fr not_active Expired - Lifetime

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