WO2014185443A1 - Soft-magnetic flat powder for magnetic sheet, magnetic sheet using same, and production method for soft-magnetic flat powder - Google Patents

Soft-magnetic flat powder for magnetic sheet, magnetic sheet using same, and production method for soft-magnetic flat powder Download PDF

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WO2014185443A1
WO2014185443A1 PCT/JP2014/062794 JP2014062794W WO2014185443A1 WO 2014185443 A1 WO2014185443 A1 WO 2014185443A1 JP 2014062794 W JP2014062794 W JP 2014062794W WO 2014185443 A1 WO2014185443 A1 WO 2014185443A1
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magnetic
powder
flat powder
sheet
flat
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PCT/JP2014/062794
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French (fr)
Japanese (ja)
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澤田　俊之
文宏 前澤
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山陽特殊製鋼株式会社
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Priority to KR1020157022460A priority Critical patent/KR20160009525A/en
Priority to CN201480022045.7A priority patent/CN105122390B/en
Publication of WO2014185443A1 publication Critical patent/WO2014185443A1/en

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    • 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
    • H01F1/12—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 soft-magnetic materials
    • H01F1/14—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 soft-magnetic materials metals or alloys
    • H01F1/20—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 soft-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/22—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 soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/24—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 soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
    • H01F1/26—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 soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated by macromolecular organic substances
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B22F1/068—Flake-like particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/006—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of flat products, e.g. sheets
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic
    • 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
    • H01F1/12—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 soft-magnetic materials
    • H01F1/14—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 soft-magnetic materials metals or alloys
    • H01F1/20—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 soft-magnetic materials metals or alloys in the form of particles, e.g. powder

Definitions

  • the present invention relates to a soft magnetic flat powder for a magnetic sheet which has excellent sheet surface smoothness and high magnetic permeability, used for various electronic devices, a magnetic sheet containing the same, and a method for producing the soft magnetic flat powder.
  • a magnetic sheet containing a soft magnetic flat powder has been used as an electromagnetic wave absorber and an antenna for RFID (Radio Frequency Identification).
  • RFID Radio Frequency Identification
  • This digitizer includes an electromagnetic induction type as disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-22661 (Patent Document 1), and a high-frequency signal transmitted from a coil built in the tip of a pen-shaped position indicator is The indicated position is detected by reading with a loop coil built in the panel-shaped position detector.
  • a sheet serving as a magnetic path for the high-frequency signal is disposed on the back surface of the loop coil.
  • a magnetic sheet in which a soft magnetic flat powder is oriented in a resin or rubber, or a soft magnetic amorphous alloy foil laminated is applied.
  • the entire detection panel can be made into one sheet, so that excellent uniformity can be obtained without any detection failure at the bonded portion such as an amorphous foil.
  • the digitizer function is applied to smartphones and tablet terminals, such mobile electronic devices are strictly demanded for miniaturization, and the magnetic sheet used as a magnetic path sheet is also highly demanded for thinning, about 50 ⁇ m or less. The thing of the same thing has come to be used. Furthermore, some tablet terminals have a liquid crystal screen of 10 inches, and a large area is required for the magnetic sheet.
  • the magnetic sheet having a thickness of 50 ⁇ m since the foreign matter is larger than the thickness of the sheet, it appears as a protrusion on the surface of the sheet, resulting in a trouble in use, and this magnetic sheet becomes a defective product.
  • the frequency of defective products increases.
  • the thickness of the magnetic sheet is reduced and the area is increased, the problem of the macro swell of the sheet cannot be ignored.
  • a high aspect ratio is considered as an important factor, and in many cases, an attritor processing condition capable of obtaining the maximum aspect ratio is adopted.
  • no method has been proposed for suppressing the above-described surface protrusion defect in an extremely thin magnetic sheet used for a magnetic path sheet for a digitizer, and the conventional technique cannot cope with it.
  • JP 2011-22661 A Japanese Patent Laid-Open No. 2005-116819
  • the inventors made flat powder with varying attritor processing time, and investigated in detail the relationship between factors such as the tap density of the flat powder and the surface protrusion defect rate of the magnetic sheet.
  • factors such as the tap density of the flat powder and the surface protrusion defect rate of the magnetic sheet.
  • the attritor processing time is excessively short and the tap density is excessively high, coarse particles that are not sufficiently flattened and remain nearly spherical, and surface protrusions are formed, and the attritor processing time is excessively long.
  • Patent Document 2 when the tap density is excessively low, it was confirmed that the flat powders were entangled and aggregated to form a coarse lump as a surface protrusion.
  • the aggregation of the flat powders has already begun, so by performing the attritor processing in a little shorter time than this, the surface protrusion of the magnetic sheet consisting of the above two factors The inventors have found that defects can be suppressed and have reached the present invention.
  • an object of the present invention is to provide a soft magnetic flat powder capable of realizing a high magnetic permeability with few projection defects when used as a magnetic sheet, a high magnetic permeability magnetic sheet using the same, and a method for producing the soft magnetic flat powder. It is to provide.
  • a soft magnetic flat powder for a magnetic sheet having excellent sheet surface smoothness and high magnetic permeability wherein the soft magnetic flat powder is obtained by flattening a soft magnetic powder.
  • the soft magnetic flat powder is The average particle size is 40-53 ⁇ m, The ratio of tap density to true density is 0.20 to 0.23, The average aspect ratio is 10-40, The average thickness is 1.6 to 3.1 ⁇ m, The oxygen content is 0.16-0.48 mass%, A soft magnetic flat powder having a nitrogen content of 10 to 250 ppm is provided.
  • the coercivity measured by applying a magnetic field in the longitudinal direction of the flat powder is 48 to 104 A / m, and the coercivity measured by applying a magnetic field in the thickness direction of the flat powder.
  • the ratio of the coercive force measured by applying a magnetic field in the thickness direction of the flat powder to the coercive force measured by applying a magnetic field in the longitudinal direction of the flat powder is 1.5 to 3.0 A / m. Can be.
  • a magnetic sheet containing the soft magnetic flat powder of the present invention and having excellent sheet surface smoothness and high magnetic permeability.
  • a method for producing the soft magnetic flat powder of the present invention Producing raw material powder by gas atomization method or disk atomization method; A flat processing step of completing attritor processing in 3 to 20 hours in a time of 60 to 95% of the processing time in which the aspect ratio of the raw material powder is maximized; Heat treating the flattened powder in a vacuum or argon atmosphere at 700-900 ° C .; A method is provided comprising:
  • FIG. 1 is a photograph taken by a scanning electron microscope showing the presence of nearly spherical particles that are not sufficiently flattened.
  • FIG. 2 is a photograph taken by a scanning electron microscope showing a lump in which flat powders are intertwined.
  • the first feature of the present invention is that the flat processing time by the attritor is set to be shorter than the maximum aspect ratio, thereby preventing the entanglement between the flat powders and suppressing the surface protrusion of the magnetic sheet. It is.
  • the inventors made flat powder with varying attritor processing time, and made a magnetic sheet with a thickness of 50 ⁇ m using this powder. When the attritor processing time was too short and too long, the sheet It was confirmed that surface defects frequently occurred.
  • the second feature of the present invention is that, as described above, the average particle diameter of the flat powder, the ratio of the tap density to the true density, the aspect ratio, despite avoiding the maximum aspect ratio at which the magnetic sheet can have the highest magnetic permeability.
  • the thickness, the oxygen content, and the nitrogen content within the ranges, the decrease in the magnetic permeability of the magnetic sheet is minimized.
  • the macro undulation of the magnetic sheet is also reduced. An unexpected effect was also observed.
  • the reason for this is estimated as follows.
  • the powder flattened by attritor processing has a high aspect ratio and at the same time warps in the thickness direction.
  • the flat powder is oriented so as to be forcibly laminated in the surface of the magnetic sheet by roll rolling or pressing, but after the pressure due to roll rolling or pressing is removed, the flat powder is The shape will be restored in the direction of. As a result, undulations occur on the surface of the magnetic sheet, and in particular, when the warpage is remarkable, the undulations become macroscopic.
  • the average particle size is excessively large, the ratio of the tap density to the true density is excessively small, the aspect ratio is excessively large, and the thickness is excessively small, the warpage of the flat powder is increased. It is thought that it becomes a factor and a factor which aims at large warpage.
  • the thickness is somewhat thick like a conventional magnetic sheet, the warpage of the flat powder is forcibly restrained by the surrounding resin or rubber, so that it is difficult to restore the warp, and the macroscopicity of the magnetic sheet This macro swell has become a problem particularly in thin magnetic sheets that have come to be used in recent years.
  • the third feature of the present invention is that the coercive force of the flat powder is defined by the values in the longitudinal direction and the thickness direction, and also by the ratio between the two, thereby reducing both the magnetic sheet permeability and surface protrusion defects. Is. Since the flat powder is laminated and oriented in the sheet surface in the magnetic sheet, conventionally, the coercive force when magnetized in the longitudinal direction has been studied. However, the coercive force when magnetized in the thickness direction includes not only the coercive force of the soft magnetic powder material but also information on crystal anisotropy and shape anisotropy.
  • the attritor processing in the present invention is completely different from the conventional condition, and by actively avoiding the condition that the maximum aspect ratio can be obtained, the sheet surface protrusion defect and the sheet macroscopicity are avoided. It aims to prevent swells.
  • the ratio of the tap density to the true density and the thickness of the flat powder specified in the present invention is positively removed from the optimum points that have been considered in the past, thereby preventing the projection of the sheet surface and the macro waviness of the sheet. It is what has been achieved.
  • a classification step of a predetermined particle size after the attritor processing or after the heat treatment it is possible to remove coarse foreign matters in the flat powder and further reduce the protrusion defect on the magnetic sheet surface. Is possible.
  • a surface treatment represented by a conventionally proposed cyan coupling agent it is possible to improve the corrosion resistance and the dispersibility in rubber by a surface treatment represented by a conventionally proposed cyan coupling agent.
  • a magnetic sheet can be produced by a conventionally proposed method. For example, it can be produced by mixing a flat powder with a solution obtained by dissolving chlorinated polyethylene or the like in toluene, and applying and drying the mixture with various presses or rolls.
  • the soft magnetic flat powder of the present invention is used for a magnetic sheet having excellent sheet surface smoothness and high magnetic permeability.
  • This soft magnetic flat powder is obtained by flattening the soft magnetic powder, has an average particle size of 40 to 53 ⁇ m, and a ratio of tap density to true density of 0.20 to 0.23.
  • the average aspect ratio is 10 to 40, the average thickness is 1.6 to 3.1 ⁇ m, the oxygen content is 0.16 to 0.48 mass%, and the nitrogen content is 10 to 250 ppm. There is something.
  • the technical significance of these numerical limitations will be described.
  • the soft magnetic flat powder of the present invention has an average particle size of 40 to 53 ⁇ m, preferably more than 43 ⁇ m and less than 51 ⁇ m, more preferably more than 45 and less than 49 ⁇ m.
  • the average particle size of the flat powder is a factor affecting the magnetic permeability, surface protrusions, and undulation of the magnetic sheet.
  • the magnetic permeability is low below 40 ⁇ m, and many surface protrusions are generated and the undulation is above 53 ⁇ m. It gets bigger.
  • the soft magnetic flat powder of the present invention has a ratio of tap density to true density of 0.20 to 0.23, preferably more than 0.20 and less than 0.23, more preferably more than 0.21 and more than 0.22. It is less than the range.
  • the ratio of the tap density to the true density of the flat powder is a factor affecting the magnetic permeability, surface protrusion, and waviness of the magnetic sheet. If it is less than 0.20, many surface protrusions occur and waviness increases. If it exceeds .23, the magnetic permeability will be low.
  • the soft magnetic flat powder of the present invention has an average aspect ratio of 10 to 40, preferably more than 15 and less than 35, more preferably more than 20 and less than 30.
  • the average aspect ratio of the flat powder is a factor affecting the magnetic permeability, surface protrusion, and waviness of the magnetic sheet. When it is less than 10, the magnetic permeability is low, and when it exceeds 40, many surface protrusions are generated and waviness occurs. It gets bigger.
  • the soft magnetic flat powder of the present invention has an average thickness of 1.6 to 3.1 ⁇ m, preferably more than 1.8 ⁇ m and less than 2.8 ⁇ m, more preferably more than 2.0 ⁇ m and less than 2.5 ⁇ m. is there.
  • the average thickness of the flat powder is a factor that affects the magnetic permeability, surface protrusions, and waviness of the magnetic sheet. If the thickness is less than 1.6 ⁇ m, many surface protrusions are generated and waviness increases, and exceeds 3.1 ⁇ m. And the magnetic permeability becomes low.
  • the soft magnetic flat powder of the present invention has an oxygen content of 0.16 to 0.48% by mass, preferably less than 0.40% by mass, more preferably less than 0.35% by mass.
  • the oxygen content of the flat powder is a factor affecting the magnetic permeability of the magnetic sheet, and if it exceeds 0.48% by mass, the magnetic permeability will be lowered.
  • the lower limit of the oxygen content is not particularly limited, but it is difficult to perform attritor processing to a sufficient aspect ratio by a normal manufacturing method and to suppress it to less than 0.16% by mass. In each process such as heat treatment, special atmosphere control is required, or special treatment such as various reductions is required, resulting in high costs. Therefore, it is preferable to control each treatment with such management that the lower limit of the oxygen content exceeds 0.20 mass% or exceeds 0.23 mass% in view of cost.
  • the soft magnetic flat powder of the present invention has a nitrogen content of 10 to 250 ppm, preferably less than 150 ppm, more preferably less than 100 ppm.
  • the nitrogen content of the flat powder is a factor that affects the magnetic permeability of the magnetic sheet. If it exceeds 250 ppm, the magnetic permeability will be low.
  • the lower limit of the nitrogen content is not particularly limited, but it is difficult to attritor to a sufficient aspect ratio by a normal production method and to suppress it to less than 10 ppm, such as atomization, attritor, heat treatment, etc.
  • the process requires special atmosphere control, or requires special treatment such as various reductions, resulting in high costs. Therefore, it is preferable to control each treatment with management such that the lower limit of the nitrogen content exceeds 20 ppm or exceeds 30 ppm in consideration of cost.
  • the soft magnetic flat powder of the present invention preferably has a coercive force measured by applying a magnetic field in the longitudinal direction of 48 to 104 A / m, more preferably more than 56 A / m and less than 96 A / m, still more preferably. Is in the range of more than 64 A / m and less than 88 A / m.
  • the coercive force measured by applying a magnetic field in the longitudinal direction of the flat powder is a factor affecting the magnetic permeability of the magnetic sheet, and flattening is not sufficient at less than 48 A / m, and flattening at more than 104 A / m. Since there are many lattice defects in the powder, the magnetic permeability of the magnetic sheet is lowered.
  • the soft magnetic flat powder of the present invention preferably has a coercive force measured by applying a magnetic field in the thickness direction of 128 to 200 A / m, more preferably more than 136 A / m and less than 184 A / m, more Preferably, it is in the range of more than 144 A / m and less than 168 A / m.
  • the coercivity measured by applying a magnetic field in the thickness direction of the flat powder is a factor that affects the magnetic permeability of the magnetic sheet.
  • the magnetic force is less than 128 A / m, flattening is not sufficient, and when the magnetic force exceeds 200 A / m. Since there are many lattice defects in the flat powder, the magnetic sheet has low magnetic permeability.
  • the soft magnetic flat powder of the present invention preferably has a ratio of coercivity measured by applying a magnetic field in the thickness direction to coercivity measured by applying a magnetic field in the longitudinal direction of 1.5 to 3.0. More preferably, it is more than 1.7 and less than 2.7, more preferably more than 1.9 and less than 2.4.
  • the ratio of the coercivity measured by applying a magnetic field in the thickness direction of the flat powder to the coercivity measured by applying a magnetic field in the longitudinal direction of the flat powder is the magnetic permeability, surface protrusion, and undulation of the magnetic sheet. When the ratio is less than 1.5, the magnetic permeability is low. When the ratio exceeds 3.0, many surface protrusions are generated and the undulation is increased.
  • the soft magnetic flat powder of the present invention is not particularly limited as long as it is composed of a known alloy used for the soft magnetic flat powder for magnetic sheets.
  • preferable alloys include Fe—Si—Al alloys and Fe—Si alloys. Fe—Ni alloy, Fe—Al alloy, Fe—Cr alloy, and Fe—Si—Cr alloy, and more preferably Fe—Si—Al alloy, Fe—Si alloy, Fe—Ni alloy, and Fe—.
  • a Si—Cr alloy is mentioned.
  • the soft magnetic flat powder of the present invention comprises a step of producing a raw material powder by a gas atomizing method or a disk atomizing method, a time of 60 to 95% of the processing time in which the aspect ratio of the raw material powder is maximum, and 3 to 20 It can be manufactured by a method including a flattening step for completing attritor processing in time and a step of heat-treating the flattened powder at 700 to 900 ° C. in a vacuum or an argon atmosphere.
  • a raw material powder is produced by a gas atomization method or a disk atomization method.
  • the gas atomization method can produce an alloy powder having a low oxygen content and a low nitrogen content, and can easily produce a flat powder having an oxygen and nitrogen content range of the present invention.
  • the shape of the alloy powder to be produced is spherical, flattening is more likely to proceed than pulverization by attritor processing, and the average particle diameter in the present invention, the ratio of tap density to true density, aspect ratio, and thickness A range of flat powders can be made.
  • the raw material powder is not particularly limited as long as it is composed of a known alloy used for the soft magnetic flat powder for magnetic sheets.
  • preferable alloys include Fe—Si—Al alloy, Fe—Si alloy, and Fe—Ni alloy.
  • Fe-Si—Al alloy, Fe-Cr alloy, and Fe-Si-Cr alloy and more preferably Fe-Si-Al alloy, Fe-Si alloy, Fe-Ni alloy, and Fe-Si-Cr alloy.
  • This flat processing step is performed for 60 to 95%, preferably more than 70% and less than 90%, more preferably more than 75% and less than 85% of the processing time at which the aspect ratio of the raw material powder becomes maximum, and 3 to
  • the attritor processing is performed in a range of 20 hours, preferably more than 4 hours and less than 19 hours, more preferably more than 5 hours and less than 18 hours.
  • coarse lumps are already generated due to the entanglement and aggregation of the flat powder, and the protrusion defects on the magnetic sheet surface frequently occur.
  • this projection defect can be suppressed by completing the attritor processing within 95% or less of the attritor processing time at which the aspect ratio becomes maximum.
  • the attritor processing is completed in less than 60% of the attritor processing time at which the aspect ratio is maximum, a powder having a nearly spherical shape that is not sufficiently flattened remains, and surface protrusion defects of the magnetic sheet frequently occur. Therefore, the flat powder of the present invention can be produced with an attritor processing time of 60 to 95%.
  • the flat powder of the present invention can be produced by setting the time to 3 to 20 hours.
  • This heat treatment step is a step for recovering lattice defects in the flat powder introduced by attritor processing and improving the magnetic permeability.
  • the heat treatment atmosphere is air or nitrogen, oxidation and nitridation proceed, and the flat powder of the present invention cannot be produced. Therefore, heat treatment in a vacuum or an inert atmosphere is necessary, and considering the production cost, the flat powder of the present invention can be produced at a low cost in a vacuum or an argon atmosphere.
  • the heat treatment temperature in this heat treatment step is 700 to 900 ° C., preferably more than 730 ° C. and less than 880 ° C., more preferably more than 750 ° C. and less than 850 ° C.
  • the heat treatment step is a step for recovering lattice defects in the flat powder introduced by the attritor processing and lowering the coercive force, and the coercive force is not sufficiently lowered below 700 ° C., and 900 ° C. When it exceeds, it will sinter and this will become a coarse lump and will increase the protrusion of a sheet
  • a powder having a predetermined component was produced by a gas atomizing method and classified to 150 ⁇ m or less.
  • Gas atomization was performed by using an alumina crucible for melting, discharging molten alloy from a nozzle having a diameter of 5 mm under the crucible, and spraying high pressure argon on the molten alloy.
  • the raw material powder thus obtained was flattened with an attritor.
  • the attritor used a ball with a diameter of 4.8 mm made by SUJ2, was put into a stirring container together with the raw material powder and industrial ethanol, and the blade rotation speed was 300 and 450 rpm.
  • the flat powder taken out of the stirring vessel after flattening and industrial ethanol were transferred to a stainless steel dish and dried at 80 ° C. for 24 hours.
  • the flat powder thus obtained was heat-treated in argon at a predetermined temperature for 2 hours and used for various evaluations.
  • the average particle size, true density, tap density, oxygen content, nitrogen content, and coercive force of the obtained flat powder were evaluated.
  • the average particle size (volume average particle size (D50)) was evaluated by a laser diffraction method, and the true density was evaluated by a gas displacement method.
  • the tap density was evaluated based on the packing density when about 80 g of flat powder was filled in a cylinder with a volume of 100 ml and the drop height was 10 mm and the number of taps was 200.
  • the coercive force was measured by filling a flat container with a resin container having a diameter of 6 mm and a height of 8 mm, and magnetizing in the height direction and magnetizing in the diameter direction.
  • the flat powder is flattened when magnetized in the height direction of the container and flattened when magnetized in the thickness direction of the flat powder and in the diameter direction of the container. It becomes the coercive force in the longitudinal direction of the powder.
  • the applied magnetic field was 144 kA / m.
  • chlorinated polyethylene was dissolved in toluene, and the obtained flat powder was mixed and dispersed. This dispersion was applied to a polyester resin to a thickness of about 1 mm and dried at normal temperature and humidity. Then, it pressed at 130 degreeC and the pressure of 15 Mpa, and obtained the magnetic sheet.
  • the magnetic sheet has a length of 150 mm, a width of 150 mm, and a thickness of 50 ⁇ m.
  • the volume filling rate of the flat powder in the magnetic sheet was about 50%. The surface of the sheet was visually observed to evaluate the number of surface protrusions.
  • seat was set
  • this magnetic sheet was cut into a donut shape having an outer diameter of 7 mm and an inner diameter of 3 mm, and impedance characteristics at 1 MHz were measured at room temperature with an impedance measuring device. From the result, permeability (real part of complex permeability: ⁇ ′ ) was calculated. Further, the cross-section of the obtained magnetic sheet was resin-filled and polished, 50 powders of “length / thickness in the longitudinal direction” were randomly measured from the optical microscope image, and the average was taken as the aspect ratio.
  • Comparative Example No. 1-4 the processing time when the maximum aspect ratio is obtained as 100% is short, the average particle size is small, the ratio of the tap density to the true density is large, the aspect ratio of the flat powder is small, The thickness is small, the oxygen content is small, the coercivity in the longitudinal direction and the coercivity in the thickness direction are small, the ratio of the coercivity in the longitudinal direction to the coercivity in the thickness direction is small, and the attritor processing time is short ( No. 3 and 4), there were many protrusion defects on the sheet surface, and a decrease in the complex transmittance of the sheet was observed.
  • Comparative Example No. 7 to 12 are processing time when the maximum aspect ratio is obtained as 100%, average particle size (excluding No. 8 to 9), ratio of tap density to true density, aspect ratio of flat powder (No 8 to 10), the thickness of the flat powder, the oxygen content, the coercive force in the longitudinal direction, and the coercive force in the thickness direction do not satisfy the conditions of the present invention.
  • Comparative Example No. Nos. 15 to 19 have a long attritor processing time (No. 17 and 18), a long processing time when the time for obtaining the maximum aspect ratio is 100% (No. 15 to 18), and a small average particle size ( No. 15 to 18), the ratio of the tap density to the true density is large (No. 15 to 18), the aspect ratio of the flat powder is large (No. 15), and the thickness of the flat powder is thin (No. 15 to 18). ), The oxygen content is large (Nos. 15 to 18), and the coercive force in the longitudinal direction and the coercive force in the thickness direction are both large. Except for 19, there are many protrusion defects on the sheet surface. Regarding the macro swell of the sheet, no. No. 15 to 18 and the reduction in the complex transmittance of the sheet is also No. It was seen in cases 16-19.
  • Comparative Example No. No. 23 has a high heat treatment temperature and a large ratio of tap density to true density, so that there are many protrusion defects on the sheet surface.
  • the processing time when the time for obtaining the maximum aspect ratio is 100% is long, the ratio of the tap density to the true density is small, the thickness of the flat powder is thin, and the longitudinal direction with respect to the coercive force in the thickness direction Since the ratio of coercive force of the sheet was large, some protrusion defects on the sheet surface were observed, and macroscopic undulation was observed.
  • Comparative Example No. No. 29 has a long attritor processing time, a long processing time when the time for obtaining the maximum aspect ratio is 100%, a small ratio of tap density to the true density, a thin flat powder thickness, and an oxygen content of In many cases, the coercive force in the longitudinal direction and the coercive force in the thickness direction were both large, so that there were many defective projections on the sheet surface, and macro swell of the sheet was observed. Comparative Example No.
  • the average particle size, the ratio of the tap density to the true density, and the aspect ratio of the flat powder are small, the thickness of the flat powder is thin, the oxygen content and the nitrogen content are high, the coercive force and the thickness in the longitudinal direction Since the coercive force value in the direction is large and the ratio of the coercive force in the longitudinal direction to the coercive force in the thickness direction is small, poor protrusion and macro waviness are observed on the sheet surface, and the complex transmittance of the sheet Decrease was observed.
  • No. which is an example of the present invention.
  • any case of 5-6, 13-14, 20-22, 26, 28, and 30-31, satisfying the conditions of the present invention there are few projection defects when used as a magnetic sheet, and macro swell is seen.

Abstract

Provided is a soft-magnetic flat powder for a magnetic sheet exhibiting excellent sheet-surface smoothness and high magnetic permeability. This soft-magnetic flat powder is obtained by flattening a soft-magnetic powder, and has an average particle size of 40-53 µm. The ratio of the tap density thereof to the true density thereof is 0.20-0.23. Furthermore, the soft-magnetic flat powder has an average aspect ratio of 10-40, an average thickness of 1.6-3.1 µm, an oxygen content of 0.16-0.48 mass%, and a nitrogen content of 10-250 ppm. According to the present invention, provided are: a soft-magnetic flat powder which, when used as a magnetic sheet, is capable of achieving a high magnetic permeability and few protrusion defects; and a magnetic sheet which has a high magnetic permeability, and in which said powder is used.

Description

磁性シート用軟磁性扁平粉末及びこれを用いた磁性シート並びに軟磁性扁平粉末の製造方法Soft magnetic flat powder for magnetic sheet, magnetic sheet using the same, and method for producing soft magnetic flat powder
　本発明は、各種の電子デバイスに用いられる、シート表面の平滑性に優れ高透磁率を有する磁性シート用軟磁性扁平粉末とこれを含有する磁性シート、並びにこの軟磁性扁平粉末の製造方法に関する。 The present invention relates to a soft magnetic flat powder for a magnetic sheet which has excellent sheet surface smoothness and high magnetic permeability, used for various electronic devices, a magnetic sheet containing the same, and a method for producing the soft magnetic flat powder.
　従来より、軟磁性扁平粉末を含有する磁性シートは、電磁波吸収体、ＲＦＩＤ（Ｒａｄｉｏ　Ｆｒｅｑｕｅｎｃｙ　Ｉｄｅｎｔｉｆｉｃａｔｉｏｎ）用アンテナとして用いられてきた。また、近年では、デジタイザと呼ばれる位置検出装置にも用いられるようになってきている。このデジタイザには、例えば特開２０１１－２２６６１号公報（特許文献１）のような電磁誘導型のものがあり、ペン形状の位置指示器の先に内蔵されるコイルより発信された高周波信号を、パネル状の位置検出器に内蔵されたループコイルにより読み取ることで指示位置を検出する。ここで、検出感度を高める目的で、ループコイルの背面には高周波信号の磁路となるシートが配置される。 Conventionally, a magnetic sheet containing a soft magnetic flat powder has been used as an electromagnetic wave absorber and an antenna for RFID (Radio Frequency Identification). In recent years, it has come to be used also for a position detection device called a digitizer. This digitizer includes an electromagnetic induction type as disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-22661 (Patent Document 1), and a high-frequency signal transmitted from a coil built in the tip of a pen-shaped position indicator is The indicated position is detected by reading with a loop coil built in the panel-shaped position detector. Here, for the purpose of increasing the detection sensitivity, a sheet serving as a magnetic path for the high-frequency signal is disposed on the back surface of the loop coil.
　この磁路となるシートとしては、軟磁性扁平粉末を樹脂やゴム中に配向させた磁性シートや、軟磁性アモルファス合金箔を貼り合わせたものなどが適用される。磁性シートを用いる場合は、検出パネル全体を１枚のシートに出来るため、アモルファス箔のような貼り合せ部での検出不良などがなく優れた均一性が得られる。 As the sheet serving as the magnetic path, a magnetic sheet in which a soft magnetic flat powder is oriented in a resin or rubber, or a soft magnetic amorphous alloy foil laminated is applied. In the case of using a magnetic sheet, the entire detection panel can be made into one sheet, so that excellent uniformity can be obtained without any detection failure at the bonded portion such as an amorphous foil.
　デジタイザ機能はスマートフォンやタブレット端末などへ適用されるが、このようなモバイル電子デバイスは小型化の要求が厳しく、磁路シートとして用いられる磁性シートにも薄肉化の要求が高く、５０μｍ以下程度の薄さのものが用いられるようになってきた。さらに、タブレット端末には液晶画面が１０インチにもなるものがあり、磁性シートにも大面積が要求されるようになってきた。 Although the digitizer function is applied to smartphones and tablet terminals, such mobile electronic devices are strictly demanded for miniaturization, and the magnetic sheet used as a magnetic path sheet is also highly demanded for thinning, about 50 μm or less. The thing of the same thing has come to be used. Furthermore, some tablet terminals have a liquid crystal screen of 10 inches, and a large area is required for the magnetic sheet.
　このような薄肉の磁性シートを一般的に適用される圧延やプレスによる方法で作製した場合、従来の厚さの磁性シートでは問題にならなかったシート表面の突起が問題となるようになってきた。すなわち、使用する軟磁性扁平粉末に、例えば１００μｍの異物が混入していた場合、従来のような５００μｍ程度の厚さの磁性シートでは異物はシート中に取り込まれてしまい、シート表面の突起とはならない。 When such a thin magnetic sheet is produced by a generally applied rolling or pressing method, protrusions on the surface of the sheet that have not been a problem with conventional magnetic sheets have become a problem. . That is, when a soft magnetic flat powder used has a foreign substance of 100 μm, for example, in a conventional magnetic sheet having a thickness of about 500 μm, the foreign substance is taken into the sheet. Don't be.
　一方、５０μｍの薄さの磁性シートでは異物はシート厚さよりも大きいため、シート表面に突起として現れてしまい、使用上のトラブルとなるためこの磁性シートは不良品となる。特に、タブレット端末のように大面積を必要とする際には、不良品の頻度が高くなってしまう。さらに、磁性シートの厚さが薄く、かつ大面積になるにしたがい、シートのマクロ的なうねりの問題も無視できなくなってきた。 On the other hand, in the magnetic sheet having a thickness of 50 μm, since the foreign matter is larger than the thickness of the sheet, it appears as a protrusion on the surface of the sheet, resulting in a trouble in use, and this magnetic sheet becomes a defective product. In particular, when a large area is required like a tablet terminal, the frequency of defective products increases. Furthermore, as the thickness of the magnetic sheet is reduced and the area is increased, the problem of the macro swell of the sheet cannot be ignored.
　従来より、磁性シートには、Ｆｅ－Ｓｉ－Ａｌ合金、Ｆｅ－Ｓｉ合金、Ｆｅ－Ｎｉ合金、Ｆｅ－Ａｌ合金、Ｆｅ－Ｃｒ合金などからなる粉末を、アトライタ（アトリッションミル）などにより扁平化したものが添加されてきた。これは、高い透磁率の磁性シートを得るために、いわゆる「Ｏｌｌｅｎｄｏｒｆｆの式」からわかるように、透磁率の高い軟磁性粉末を用いること、反磁界を下げるため磁化方向に高いアスペクト比を持つ扁平粉末を用いること、磁性シート中に軟磁性粉末を高充填することが重要であるためである。 Conventionally, powders made of Fe—Si—Al alloy, Fe—Si alloy, Fe—Ni alloy, Fe—Al alloy, Fe—Cr alloy, etc. are flattened on the magnetic sheet using an attritor (attrition mill) or the like. Has been added. This is because, in order to obtain a magnetic sheet having a high magnetic permeability, a so-called “Olendorff's formula” uses a soft magnetic powder having a high magnetic permeability, and a flatness having a high aspect ratio in the magnetization direction in order to reduce the demagnetizing field. This is because it is important to use powder and to highly fill the magnetic sheet with soft magnetic powder.
　特に、高いアスペクト比は重要な因子と考えられており、多くの場合、最大のアスペクト比が得られるアトライタ加工条件が採用されている。しかしながら、デジタイザ用磁路シートに用いる極めて薄い磁性シートなどにおける、上述した表面突起不良の抑制に関する方法は提案されておらず、従来の技術では対応しきれない状況になってきている。 Especially, a high aspect ratio is considered as an important factor, and in many cases, an attritor processing condition capable of obtaining the maximum aspect ratio is adopted. However, no method has been proposed for suppressing the above-described surface protrusion defect in an extremely thin magnetic sheet used for a magnetic path sheet for a digitizer, and the conventional technique cannot cope with it.
特開２０１１－２２６６１号公報JP 2011-22661 A 特開２００５－１１６８１９号公報Japanese Patent Laid-Open No. 2005-116819
　そこで発明者らは、アトライタ加工の時間を変化させた扁平粉末を作製し、扁平粉末のタップ密度などの因子と、磁性シートの表面突起不良率との関係を詳細に調査した。その結果、アトライタ加工時間が過度に短く、タップ密度が過度に高い場合は、十分に扁平化されていない球状に近い粗大粒子が残存し表面突起となること、及び、アトライタ加工時間が過度に長く、例えば特開２００５－１１６８１９号公報（特許文献２）のように、タップ密度が過度に低い場合は、扁平粉末同士が絡み合い凝集し、粗大な塊となり表面突起となることを確認した。 Therefore, the inventors made flat powder with varying attritor processing time, and investigated in detail the relationship between factors such as the tap density of the flat powder and the surface protrusion defect rate of the magnetic sheet. As a result, when the attritor processing time is excessively short and the tap density is excessively high, coarse particles that are not sufficiently flattened and remain nearly spherical, and surface protrusions are formed, and the attritor processing time is excessively long. For example, as in Japanese Patent Application Laid-Open No. 2005-116819 (Patent Document 2), when the tap density is excessively low, it was confirmed that the flat powders were entangled and aggregated to form a coarse lump as a surface protrusion.
　なお、最大のアスペクト比が得られるアトライタ加工時間では、すでに扁平粉末同士の凝集が始まっているため、これよりも少し短い時間でアトライタ加工することにより、上記二つの要因からなる磁性シートの表面突起不良を抑制できることを見出し本発明に至った。 In addition, at the attritor processing time at which the maximum aspect ratio can be obtained, the aggregation of the flat powders has already begun, so by performing the attritor processing in a little shorter time than this, the surface protrusion of the magnetic sheet consisting of the above two factors The inventors have found that defects can be suppressed and have reached the present invention.
　したがって、本発明の目的は、磁性シートとして用いる場合に突起不良が少なく、高い透磁率を実現できる軟磁性扁平粉末とこれを用いた高透磁率磁性シート、並びにこの軟磁性扁平粉末の製造方法を提供することにある。 Accordingly, an object of the present invention is to provide a soft magnetic flat powder capable of realizing a high magnetic permeability with few projection defects when used as a magnetic sheet, a high magnetic permeability magnetic sheet using the same, and a method for producing the soft magnetic flat powder. It is to provide.
　本発明の一態様によれば、シート表面の平滑性に優れ高透磁率を有する磁性シート用軟磁性扁平粉末であって、該軟磁性扁平粉末が軟磁性粉末を扁平化処理することにより得られたものであり、該軟磁性扁平粉末は、
　平均粒径が４０～５３μｍであり、
　真密度に対するタップ密度の比が０．２０～０．２３であり、
　平均アスペクト比が１０～４０であり、
　平均厚さが１．６～３．１μｍであり、
　酸素含有量が０．１６～０．４８質量％であり、
　窒素含有量が１０～２５０ｐｐｍである、軟磁性扁平粉末が提供される。 According to one aspect of the present invention, there is provided a soft magnetic flat powder for a magnetic sheet having excellent sheet surface smoothness and high magnetic permeability, wherein the soft magnetic flat powder is obtained by flattening a soft magnetic powder. The soft magnetic flat powder is
The average particle size is 40-53 μm,
The ratio of tap density to true density is 0.20 to 0.23,
The average aspect ratio is 10-40,
The average thickness is 1.6 to 3.1 μm,
The oxygen content is 0.16-0.48 mass%,
A soft magnetic flat powder having a nitrogen content of 10 to 250 ppm is provided.
　本発明の好ましい態様によれば、扁平粉末の長手方向に磁場を印加して測定した保磁力が４８～１０４Ａ／ｍであり、扁平粉末の厚さ方向に磁場を印加して測定した保磁力が１２８～２００Ａ／ｍであり、扁平粉末の長手方向に磁場を印加して測定した保磁力に対する扁平粉末の厚さ方向に磁場を印加して測定した保磁力の比が１．５～３．０であることができる。 According to a preferred embodiment of the present invention, the coercivity measured by applying a magnetic field in the longitudinal direction of the flat powder is 48 to 104 A / m, and the coercivity measured by applying a magnetic field in the thickness direction of the flat powder. The ratio of the coercive force measured by applying a magnetic field in the thickness direction of the flat powder to the coercive force measured by applying a magnetic field in the longitudinal direction of the flat powder is 1.5 to 3.0 A / m. Can be.
　本発明の別の一態様によれば、本発明の軟磁性扁平粉末を含有する、シート表面の平滑性に優れ高透磁率を有する磁性シートが提供される。 According to another aspect of the present invention, there is provided a magnetic sheet containing the soft magnetic flat powder of the present invention and having excellent sheet surface smoothness and high magnetic permeability.
　本発明の更に別の一態様によれば、本発明の軟磁性扁平粉末の製造方法であって、
　ガスアトマイズ法又はディスクアトマイズ法により原料粉末を作製する工程と、
　前記原料粉末のアスペクト比が最大となる加工時間の６０～９５％の時間で、かつ３～２０時間でアトライタ加工を完了する扁平加工工程と、
　前記扁平加工された粉末を真空又はアルゴン雰囲気で７００～９００℃で熱処理する工程と、
を含む、方法が提供される。 According to still another aspect of the present invention, there is provided a method for producing the soft magnetic flat powder of the present invention,
Producing raw material powder by gas atomization method or disk atomization method;
A flat processing step of completing attritor processing in 3 to 20 hours in a time of 60 to 95% of the processing time in which the aspect ratio of the raw material powder is maximized;
Heat treating the flattened powder in a vacuum or argon atmosphere at 700-900 ° C .;
A method is provided comprising:
図１は、十分に扁平化されていない球状に近い粒子の存在を示す走査型電子顕微鏡による写真である。FIG. 1 is a photograph taken by a scanning electron microscope showing the presence of nearly spherical particles that are not sufficiently flattened. 図２は、扁平粉末同志が絡み合った塊を示す走査型電子顕微鏡による写真である。FIG. 2 is a photograph taken by a scanning electron microscope showing a lump in which flat powders are intertwined.
　以下、本発明の特徴を詳細に説明する。本発明における第１の特徴は、アトライタによる扁平加工時間を、最大のアスペクト比が得られるよりも短時間とすることで、扁平粉末同士の絡み合いを防止し、磁性シートの表面突起を抑制することである。発明者らは、アトライタ加工時間を変化させた扁平粉末を作製し、これを使用した厚さ５０μｍの磁性シートを作製したところ、アトライタ加工時間が過度に短い場合と、過度に長い場合に、シート表面の突起不良が多発することを確認した。 Hereinafter, the features of the present invention will be described in detail. The first feature of the present invention is that the flat processing time by the attritor is set to be shorter than the maximum aspect ratio, thereby preventing the entanglement between the flat powders and suppressing the surface protrusion of the magnetic sheet. It is. The inventors made flat powder with varying attritor processing time, and made a magnetic sheet with a thickness of 50 μm using this powder. When the attritor processing time was too short and too long, the sheet It was confirmed that surface defects frequently occurred.
　さらに、この突起部を走査型電子顕微鏡（ＳＥＭ）により観察したところ、図１に示すように、アトライタ加工時間が過度に短い場合は、十分に扁平化されていない球状に近い粒子が確認された。一方、図２に示すように、アトライタ加工時間が過度に長い場合は、扁平粉末同士が絡み合った塊が確認された。また、扁平粉末同士の絡み合いは、アスペクト比が最大になるアトライタ加工時間の少し前から始まっていることがわかった。 Furthermore, when this protrusion was observed with a scanning electron microscope (SEM), as shown in FIG. 1, when the attritor processing time was excessively short, particles that were not flattened and were nearly flat were confirmed. . On the other hand, as shown in FIG. 2, when the attritor processing time was excessively long, a lump in which flat powders were entangled with each other was confirmed. In addition, it was found that the entanglement between the flat powders started slightly before the attritor processing time when the aspect ratio reached the maximum.
　したがって、アトライタによる加工において、ごく加工初期には確率的にメディア（硬質球）との衝突回数が少なく球状に近い形状を維持した粉末が残存しているが、加工が進むにつれ均一な扁平化が進み、その後、扁平粉末同士の絡み合いが始まり、やがて最大のアスペクト比が得られる。さらに、最大のアスペクト比が得られた後は、扁平粉末が千切れ始め、粉砕による微粉化が始まっていた。 Therefore, in processing with an attritor, powder that maintains a nearly spherical shape with a small number of collisions with the medium (hard sphere) remains probabilistically at the very beginning of processing, but uniform flattening as processing proceeds. After that, the entanglement between the flat powders begins and eventually the maximum aspect ratio is obtained. Furthermore, after the maximum aspect ratio was obtained, the flat powder began to be broken and pulverization by pulverization began.
　本発明における第２の特徴は、上述のように最も磁性シートの透磁率が高く出来る最大のアスペクト比を避けるにもかかわらず、扁平粉末の平均粒径、真密度に対するタップ密度の比、アスペクト比、厚さ、酸素含有量、及び窒素含有量を規定する範囲にすることで、磁性シートの透磁率の低下を最小限に留めたことである。さらに、軟磁性粉末の平均粒径の上限、真密度に対するタップ密度の比の下限、アスペクト比の上限、厚さの下限を本発明範囲に規定することにより、磁性シートのマクロ的なうねりも低減できる意外な効果も認められた。 The second feature of the present invention is that, as described above, the average particle diameter of the flat powder, the ratio of the tap density to the true density, the aspect ratio, despite avoiding the maximum aspect ratio at which the magnetic sheet can have the highest magnetic permeability. By setting the thickness, the oxygen content, and the nitrogen content within the ranges, the decrease in the magnetic permeability of the magnetic sheet is minimized. Furthermore, by defining the upper limit of the average particle size of the soft magnetic powder, the lower limit of the ratio of the tap density to the true density, the upper limit of the aspect ratio, and the lower limit of the thickness within the scope of the present invention, the macro undulation of the magnetic sheet is also reduced. An unexpected effect was also observed.
　この理由は以下のことが推測される。アトライタ加工などにより扁平化された粉末は、高いアスペクト比を持つと同時に、厚さ方向に反りが出てしまう。磁性シートの作製時には、ロール圧延やプレス加工によって扁平粉末は磁性シート面内に強制的に積層するように配向するが、ロール圧延やプレス加工による圧力が除去された後、扁平粉末は元の反りの方向に形状を復元してしまう。これにより磁性シートの表面には起伏が発生し、特に反りが顕著な場合にはマクロ的なうねりになってしまう。 The reason for this is estimated as follows. The powder flattened by attritor processing has a high aspect ratio and at the same time warps in the thickness direction. During the production of the magnetic sheet, the flat powder is oriented so as to be forcibly laminated in the surface of the magnetic sheet by roll rolling or pressing, but after the pressure due to roll rolling or pressing is removed, the flat powder is The shape will be restored in the direction of. As a result, undulations occur on the surface of the magnetic sheet, and in particular, when the warpage is remarkable, the undulations become macroscopic.
　ここで、平均粒径が過度に大きいこと、真密度に対するタップ密度の比が過度に小さいこと、アスペクト比が過度に大きいこと、厚さが過度に小さいことが扁平粉末の反りを大きくしてしまう因子になっているとともに反りが大きいことを図る因子になっていると考えられる。なお、従来の磁性シートのように、厚さがある程度厚い場合には、扁平粉末の反りが周囲の樹脂やゴムにより強制的に拘束されるため、反りの復元が困難で、磁性シートのマクロ的なうねりにはならなかったが、近年用いられるようになってきた薄い磁性シートでは、特にこのマクロ的うねりが問題となってきている。 Here, when the average particle size is excessively large, the ratio of the tap density to the true density is excessively small, the aspect ratio is excessively large, and the thickness is excessively small, the warpage of the flat powder is increased. It is thought that it becomes a factor and a factor which aims at large warpage. In addition, when the thickness is somewhat thick like a conventional magnetic sheet, the warpage of the flat powder is forcibly restrained by the surrounding resin or rubber, so that it is difficult to restore the warp, and the macroscopicity of the magnetic sheet This macro swell has become a problem particularly in thin magnetic sheets that have come to be used in recent years.
　本発明における第３の特徴は、扁平粉末の保磁力について、長手方向と厚さ方向の値と、さらには両者の比を規定することで、磁性シートの透磁率と表面突起不良の低減を両立していることである。磁性シート中で扁平粉末はシート面内に積層し配向しているため、従来は長手方向に磁化した場合の保磁力について検討されてきた。しかしながら、厚さ方向に磁化した場合の保磁力は、単に軟磁性粉末の素材の保磁力だけでなく、結晶的な異方化や形状的な異方化の情報を含んでいる。特に、長手方向及び厚さ方向の保磁力の絶対値とともに、両者の比を規定することにより、単に磁性シートの透磁率を高くするだけでなく、シートの表面突起やマクロ的うねりを抑制する因子として活用できることを見出した。 The third feature of the present invention is that the coercive force of the flat powder is defined by the values in the longitudinal direction and the thickness direction, and also by the ratio between the two, thereby reducing both the magnetic sheet permeability and surface protrusion defects. Is. Since the flat powder is laminated and oriented in the sheet surface in the magnetic sheet, conventionally, the coercive force when magnetized in the longitudinal direction has been studied. However, the coercive force when magnetized in the thickness direction includes not only the coercive force of the soft magnetic powder material but also information on crystal anisotropy and shape anisotropy. In particular, by defining the ratio of the two together with the absolute value of the coercive force in the longitudinal direction and the thickness direction, the factor that not only increases the magnetic permeability of the magnetic sheet, but also suppresses surface protrusions and macro waviness of the sheet. I found that it can be used as.
　以上に述べたように、本発明におけるアトライタ加工は従来の条件とは思想が全く異なり、積極的に最大のアスペクト比が得られる条件を回避することで、シート表面の突起不良やシートのマクロ的うねりを防止することを狙ったものである。また、本発明で規定する扁平粉末の、真密度に対するタップ密度の比や厚さも、従来考えられてきた最適なポイントを積極的に外すことにより、シート表面の突起やシートのマクロ的うねりを防止することを実現したものである。 As described above, the attritor processing in the present invention is completely different from the conventional condition, and by actively avoiding the condition that the maximum aspect ratio can be obtained, the sheet surface protrusion defect and the sheet macroscopicity are avoided. It aims to prevent swells. In addition, the ratio of the tap density to the true density and the thickness of the flat powder specified in the present invention is positively removed from the optimum points that have been considered in the past, thereby preventing the projection of the sheet surface and the macro waviness of the sheet. It is what has been achieved.
　さらに、本発明の扁平粉末について、アトライタ加工後や熱処理後に所定の粒度の分級工程を追加することにより、扁平粉末中の粗大異物を除去し、よりいっそう磁性シート表面の突起不良を低減することも可能である。また、従来から提案されているシアン系カップリング剤に代表される表面処理により、耐食性を改善したりゴムへの分散性を改善することも可能である。また、磁性シートの製造方法も従来提案されている方法で可能である。例えば、トルエンに塩素化ポリエチレンなどを溶解したものに扁平粉末を混合し、これを塗布、乾燥させたものを各種のプレスやロールで圧縮することで製造可能である。 Furthermore, about the flat powder of the present invention, by adding a classification step of a predetermined particle size after the attritor processing or after the heat treatment, it is possible to remove coarse foreign matters in the flat powder and further reduce the protrusion defect on the magnetic sheet surface. Is possible. In addition, it is possible to improve the corrosion resistance and the dispersibility in rubber by a surface treatment represented by a conventionally proposed cyan coupling agent. In addition, a magnetic sheet can be produced by a conventionally proposed method. For example, it can be produced by mixing a flat powder with a solution obtained by dissolving chlorinated polyethylene or the like in toluene, and applying and drying the mixture with various presses or rolls.
　軟磁性扁平粉末
　本発明の軟磁性扁平粉末は、シート表面の平滑性に優れ高透磁率を有する磁性シートに用いられるものである。この軟磁性扁平粉末は、軟磁性粉末を扁平化処理することにより得られたものであり、平均粒径が４０～５３μｍであり、真密度に対するタップ密度の比が０．２０～０．２３であり、平均アスペクト比が１０～４０であり、平均厚さが１．６～３．１μｍであり、酸素含有量が０．１６～０．４８質量％であり、窒素含有量が１０～２５０ｐｐｍであるものである。以下、これらの数値限定の技術的意義について説明する。 Soft magnetic flat powder The soft magnetic flat powder of the present invention is used for a magnetic sheet having excellent sheet surface smoothness and high magnetic permeability. This soft magnetic flat powder is obtained by flattening the soft magnetic powder, has an average particle size of 40 to 53 μm, and a ratio of tap density to true density of 0.20 to 0.23. The average aspect ratio is 10 to 40, the average thickness is 1.6 to 3.1 μm, the oxygen content is 0.16 to 0.48 mass%, and the nitrogen content is 10 to 250 ppm. There is something. Hereinafter, the technical significance of these numerical limitations will be described.
　本発明の軟磁性扁平粉末は、平均粒径が４０～５３μｍ、好ましくは４３μｍを超え５１μｍ未満であり、より好ましくは４５を超え４９μｍ未満の範囲である。本発明において扁平粉末の平均粒径は磁性シートの透磁率、表面突起、及びうねりに影響する因子であり、４０μｍ未満では透磁率が低くなり、５３μｍを超えると表面突起が多く発生するとともにうねりが大きくなってしまう。 The soft magnetic flat powder of the present invention has an average particle size of 40 to 53 μm, preferably more than 43 μm and less than 51 μm, more preferably more than 45 and less than 49 μm. In the present invention, the average particle size of the flat powder is a factor affecting the magnetic permeability, surface protrusions, and undulation of the magnetic sheet. The magnetic permeability is low below 40 μm, and many surface protrusions are generated and the undulation is above 53 μm. It gets bigger.
　本発明の軟磁性扁平粉末は、真密度に対するタップ密度の比が０．２０～０．２３、好ましくは０．２０を超え０．２３未満であり、より好ましくは０．２１を超え０．２２未満の範囲である。本発明において扁平粉末の真密度に対するタップ密度の比は磁性シートの透磁率、表面突起、及びうねりに影響する因子であり、０．２０未満では表面突起が多く発生するとともにうねりが大きくなり、０．２３を超えると透磁率が低くなってしまう。 The soft magnetic flat powder of the present invention has a ratio of tap density to true density of 0.20 to 0.23, preferably more than 0.20 and less than 0.23, more preferably more than 0.21 and more than 0.22. It is less than the range. In the present invention, the ratio of the tap density to the true density of the flat powder is a factor affecting the magnetic permeability, surface protrusion, and waviness of the magnetic sheet. If it is less than 0.20, many surface protrusions occur and waviness increases. If it exceeds .23, the magnetic permeability will be low.
　本発明の軟磁性扁平粉末は、平均アスペクト比が１０～４０、好ましくは１５を超え３５未満であり、より好ましくは２０を超え３０未満の範囲である。本発明において扁平粉末の平均アスペクト比は磁性シートの透磁率、表面突起、及びうねりに影響する因子であり、１０未満では透磁率が低くなり、４０を超えると表面突起が多く発生するとともにうねりが大きくなってしまう。 The soft magnetic flat powder of the present invention has an average aspect ratio of 10 to 40, preferably more than 15 and less than 35, more preferably more than 20 and less than 30. In the present invention, the average aspect ratio of the flat powder is a factor affecting the magnetic permeability, surface protrusion, and waviness of the magnetic sheet. When it is less than 10, the magnetic permeability is low, and when it exceeds 40, many surface protrusions are generated and waviness occurs. It gets bigger.
　本発明の軟磁性扁平粉末は、平均厚さが１．６～３．１μｍ、好ましくは１．８μｍを超え２．８μｍ未満であり、より好ましくは２．０μｍを超え２．５μｍ未満の範囲である。本発明において扁平粉末の平均厚さは磁性シートの透磁率、表面突起、及びうねりに影響する因子であり、１．６μｍ未満では表面突起が多く発生するとともにうねりが大きくなり、３．１μｍを超えると透磁率が低くなってしまう。 The soft magnetic flat powder of the present invention has an average thickness of 1.6 to 3.1 μm, preferably more than 1.8 μm and less than 2.8 μm, more preferably more than 2.0 μm and less than 2.5 μm. is there. In the present invention, the average thickness of the flat powder is a factor that affects the magnetic permeability, surface protrusions, and waviness of the magnetic sheet. If the thickness is less than 1.6 μm, many surface protrusions are generated and waviness increases, and exceeds 3.1 μm. And the magnetic permeability becomes low.
　本発明の軟磁性扁平粉末は、酸素含有量が０．１６～０．４８質量％、好ましくは０．４０質量％未満であり、より好ましくは０．３５質量％未満の範囲である。本発明において扁平粉末の酸素含有量は磁性シートの透磁率に影響する因子であり、０．４８質量％を超えると透磁率が低くなってしまう。なお、磁性シートの特性に関して、酸素含有量の下限は特に制限はないが、通常の製法で十分なアスペクト比までアトライタ加工し、０．１６質量％未満に抑えることは困難であり、アトマイズ、アトライタ、熱処理など各工程において特別な雰囲気制御を要したり、あるいは各種還元などの特別な処理が必要となりコスト高となる。したがって、酸素含有量の下限が、０．２０質量％を超える、あるいは０．２３質量％を超えるといった程度の管理で各処理を制御することがコストを考慮すると好ましい。 The soft magnetic flat powder of the present invention has an oxygen content of 0.16 to 0.48% by mass, preferably less than 0.40% by mass, more preferably less than 0.35% by mass. In the present invention, the oxygen content of the flat powder is a factor affecting the magnetic permeability of the magnetic sheet, and if it exceeds 0.48% by mass, the magnetic permeability will be lowered. Regarding the characteristics of the magnetic sheet, the lower limit of the oxygen content is not particularly limited, but it is difficult to perform attritor processing to a sufficient aspect ratio by a normal manufacturing method and to suppress it to less than 0.16% by mass. In each process such as heat treatment, special atmosphere control is required, or special treatment such as various reductions is required, resulting in high costs. Therefore, it is preferable to control each treatment with such management that the lower limit of the oxygen content exceeds 0.20 mass% or exceeds 0.23 mass% in view of cost.
　本発明の軟磁性扁平粉末は、窒素含有量が１０～２５０ｐｐｍ、好ましくは１５０ｐｐｍ未満であり、より好ましくは１００ｐｐｍ未満の範囲である。本発明において扁平粉末の窒素含有量は磁性シートの透磁率に影響する因子であり、２５０ｐｐｍを超えると透磁率が低くなってしまう。なお、磁性シートの特性に関して、窒素含有量の下限は特に制限はないが、通常の製法で十分なアスペクト比までアトライタ加工し、１０ｐｐｍ未満に抑えることは困難であり、アトマイズ、アトライタ、熱処理など各工程において特別な雰囲気制御を要したり、あるいは各種還元などの特別な処理が必要となりコスト高となる。したがって、窒素含有量の下限が、２０ｐｐｍを超える、あるいは３０ｐｐｍを超えるといった程度の管理で各処理を制御することがコストを考慮すると好ましい。 The soft magnetic flat powder of the present invention has a nitrogen content of 10 to 250 ppm, preferably less than 150 ppm, more preferably less than 100 ppm. In the present invention, the nitrogen content of the flat powder is a factor that affects the magnetic permeability of the magnetic sheet. If it exceeds 250 ppm, the magnetic permeability will be low. Regarding the characteristics of the magnetic sheet, the lower limit of the nitrogen content is not particularly limited, but it is difficult to attritor to a sufficient aspect ratio by a normal production method and to suppress it to less than 10 ppm, such as atomization, attritor, heat treatment, etc. The process requires special atmosphere control, or requires special treatment such as various reductions, resulting in high costs. Therefore, it is preferable to control each treatment with management such that the lower limit of the nitrogen content exceeds 20 ppm or exceeds 30 ppm in consideration of cost.
　本発明の軟磁性扁平粉末は、長手方向に磁場を印加して測定した保磁力が４８～１０４Ａ／ｍを有するのが好ましく、より好ましくは５６Ａ／ｍを超え９６Ａ／ｍ未満であり、さらに好ましくは６４Ａ／ｍを超え８８Ａ／ｍ未満の範囲である。本発明において扁平粉末の長手方向に磁場を印加して測定した保磁力は磁性シートの透磁率に影響する因子であり、４８Ａ／ｍ未満では扁平化が十分ではなく、１０４Ａ／ｍを超えると扁平粉末中の格子欠陥が多いため磁性シートの透磁率が低くなってしまう。 The soft magnetic flat powder of the present invention preferably has a coercive force measured by applying a magnetic field in the longitudinal direction of 48 to 104 A / m, more preferably more than 56 A / m and less than 96 A / m, still more preferably. Is in the range of more than 64 A / m and less than 88 A / m. In the present invention, the coercive force measured by applying a magnetic field in the longitudinal direction of the flat powder is a factor affecting the magnetic permeability of the magnetic sheet, and flattening is not sufficient at less than 48 A / m, and flattening at more than 104 A / m. Since there are many lattice defects in the powder, the magnetic permeability of the magnetic sheet is lowered.
　本発明の軟磁性扁平粉末は、厚さ方向に磁場を印加して測定した保磁力が１２８～２００Ａ／ｍを有するのが好ましく、より好ましくは１３６Ａ／ｍを超え１８４Ａ／ｍ未満であり、より好ましくは１４４Ａ／ｍを超え１６８Ａ／ｍ未満の範囲である。本発明において扁平粉末の厚さ方向に磁場を印加して測定した保磁力は磁性シートの透磁率に影響する因子であり、１２８Ａ／ｍ未満では扁平化が十分ではなく、２００Ａ／ｍを超えると扁平粉末中の格子欠陥が多いため磁性シートの透磁率が低くなってしまう。 The soft magnetic flat powder of the present invention preferably has a coercive force measured by applying a magnetic field in the thickness direction of 128 to 200 A / m, more preferably more than 136 A / m and less than 184 A / m, more Preferably, it is in the range of more than 144 A / m and less than 168 A / m. In the present invention, the coercivity measured by applying a magnetic field in the thickness direction of the flat powder is a factor that affects the magnetic permeability of the magnetic sheet. When the magnetic force is less than 128 A / m, flattening is not sufficient, and when the magnetic force exceeds 200 A / m. Since there are many lattice defects in the flat powder, the magnetic sheet has low magnetic permeability.
　本発明の軟磁性扁平粉末は、長手方向に磁場を印加して測定した保磁力に対する厚さ方向に磁場を印加して測定した保磁力の比が１．５～３．０を有するのが好ましく、より好ましくは１．７を超え２．７未満であり、より好ましくは１．９を超え２．４未満の範囲である。本発明において扁平粉末の長手方向に磁場を印加して測定した保磁力に対する扁平粉末の厚さ方向に磁場を印加して測定した保磁力の比は、磁性シートの透磁率、表面突起、及びうねりに影響する因子であり、１．５未満では透磁率が低くなり、３．０を超えると表面突起が多く発生するとともにうねりが大きくなってしまう。 The soft magnetic flat powder of the present invention preferably has a ratio of coercivity measured by applying a magnetic field in the thickness direction to coercivity measured by applying a magnetic field in the longitudinal direction of 1.5 to 3.0. More preferably, it is more than 1.7 and less than 2.7, more preferably more than 1.9 and less than 2.4. In the present invention, the ratio of the coercivity measured by applying a magnetic field in the thickness direction of the flat powder to the coercivity measured by applying a magnetic field in the longitudinal direction of the flat powder is the magnetic permeability, surface protrusion, and undulation of the magnetic sheet. When the ratio is less than 1.5, the magnetic permeability is low. When the ratio exceeds 3.0, many surface protrusions are generated and the undulation is increased.
　本発明の軟磁性扁平粉末は、磁性シート用軟磁性扁平粉末に用いられる公知の合金で構成すればよく特に限定されないが、好ましい合金の例としては、Ｆｅ－Ｓｉ－Ａｌ合金、Ｆｅ－Ｓｉ合金、Ｆｅ－Ｎｉ合金、Ｆｅ－Ａｌ合金、Ｆｅ－Ｃｒ合金、及びＦｅ－Ｓｉ－Ｃｒ合金が挙げられ、より好ましくはＦｅ－Ｓｉ－Ａｌ合金、Ｆｅ－Ｓｉ合金、Ｆｅ－Ｎｉ合金、及びＦｅ－Ｓｉ－Ｃｒ合金が挙げられる。 The soft magnetic flat powder of the present invention is not particularly limited as long as it is composed of a known alloy used for the soft magnetic flat powder for magnetic sheets. Examples of preferable alloys include Fe—Si—Al alloys and Fe—Si alloys. Fe—Ni alloy, Fe—Al alloy, Fe—Cr alloy, and Fe—Si—Cr alloy, and more preferably Fe—Si—Al alloy, Fe—Si alloy, Fe—Ni alloy, and Fe—. A Si—Cr alloy is mentioned.
　製造方法
　本発明の軟磁性扁平粉末は、ガスアトマイズ法又はディスクアトマイズ法により原料粉末を作製する工程と、原料粉末のアスペクト比が最大となる加工時間の６０～９５％の時間で、かつ３～２０時間でアトライタ加工を完了する扁平加工工程と、扁平加工された粉末を真空又はアルゴン雰囲気で７００～９００℃で熱処理する工程とを含む方法により製造することができる。 Production Method The soft magnetic flat powder of the present invention comprises a step of producing a raw material powder by a gas atomizing method or a disk atomizing method, a time of 60 to 95% of the processing time in which the aspect ratio of the raw material powder is maximum, and 3 to 20 It can be manufactured by a method including a flattening step for completing attritor processing in time and a step of heat-treating the flattened powder at 700 to 900 ° C. in a vacuum or an argon atmosphere.
　本発明の製造方法においては、先ず、ガスアトマイズ法又はディスクアトマイズ法により原料粉末を作製する。ガスアトマイズ法は、他の粉末作製方法と比較し、酸素含有量及び窒素含有量の低い合金粉末を製造することができ、本発明の酸素及び窒素含有量範囲の扁平粉末を作製しやすい。また、作製される合金粉末の形状が球状であることからアトライタ加工により粉砕よりも扁平化が進行しやすく、本発明における平均粒径、真密度に対するタップ密度の比、アスペクト比、及び厚さの範囲の扁平粉末を作製することができる。 In the production method of the present invention, first, a raw material powder is produced by a gas atomization method or a disk atomization method. Compared with other powder production methods, the gas atomization method can produce an alloy powder having a low oxygen content and a low nitrogen content, and can easily produce a flat powder having an oxygen and nitrogen content range of the present invention. Further, since the shape of the alloy powder to be produced is spherical, flattening is more likely to proceed than pulverization by attritor processing, and the average particle diameter in the present invention, the ratio of tap density to true density, aspect ratio, and thickness A range of flat powders can be made.
　原料粉末は、磁性シート用軟磁性扁平粉末に用いられる公知の合金で構成すればよく特に限定されないが、好ましい合金の例としては、Ｆｅ－Ｓｉ－Ａｌ合金、Ｆｅ－Ｓｉ合金、Ｆｅ－Ｎｉ合金、Ｆｅ－Ａｌ合金、Ｆｅ－Ｃｒ合金、及びＦｅ－Ｓｉ－Ｃｒ合金が挙げられ、より好ましくはＦｅ－Ｓｉ－Ａｌ合金、Ｆｅ－Ｓｉ合金、Ｆｅ－Ｎｉ合金、及びＦｅ－Ｓｉ－Ｃｒ合金が挙げられる。 The raw material powder is not particularly limited as long as it is composed of a known alloy used for the soft magnetic flat powder for magnetic sheets. Examples of preferable alloys include Fe—Si—Al alloy, Fe—Si alloy, and Fe—Ni alloy. Fe-Al alloy, Fe-Cr alloy, and Fe-Si-Cr alloy, and more preferably Fe-Si-Al alloy, Fe-Si alloy, Fe-Ni alloy, and Fe-Si-Cr alloy. Can be mentioned.
　次いで、この原料粉末に対して扁平加工工程を行う。この扁平加工工程は、原料粉末のアスペクト比が最大となる加工時間の６０～９５％、好ましくは７０％を超え９０％未満、より好ましくは７５％を超え８５％未満の時間で、かつ３～２０時間、好ましくは４時間を超え１９時間未満、より好ましくは５時間を超え１８時間未満の範囲でアトライタ加工を完了するように行われる。上述のようにアスペクト比が最大になるアトライタ加工時には、既に扁平粉末の絡み合い、凝集による、粗大な塊が発生しており、磁性シート表面の突起不良が多発している。したがって、アスペクト比が最大となるアトライタ加工時間の９５％以下でアトライタ加工を完了することで、この突起不良を抑制することができる。一方、アスペクト比が最大となるアトライタ加工時間の６０％未満でアトライタ加工を完了すると、十分に扁平化していない球状に近い形状の粉末が残存しており、磁性シートの表面突起不良が多発する。したがって、６０～９５％のアトライタ加工時間により、本発明の扁平粉末を作製することができる。ところで、上述のように、アトライタ加工時間とともに被加工粉末の形状は刻々と変化する。３時間未満では十分に扁平化していない球状に近い形状の粉末が残存しており磁性シートの表面突起不良が多発し、２０時間を超えると扁平粉末の絡み合い、凝集による、粗大な塊が発生し磁性シートの表面突起不良が多発するため、３～２０時間とすることで本発明の扁平粉末を作製することができる。 Next, a flattening process is performed on this raw material powder. This flat processing step is performed for 60 to 95%, preferably more than 70% and less than 90%, more preferably more than 75% and less than 85% of the processing time at which the aspect ratio of the raw material powder becomes maximum, and 3 to The attritor processing is performed in a range of 20 hours, preferably more than 4 hours and less than 19 hours, more preferably more than 5 hours and less than 18 hours. As described above, at the time of the attritor processing in which the aspect ratio is maximized, coarse lumps are already generated due to the entanglement and aggregation of the flat powder, and the protrusion defects on the magnetic sheet surface frequently occur. Therefore, this projection defect can be suppressed by completing the attritor processing within 95% or less of the attritor processing time at which the aspect ratio becomes maximum. On the other hand, when the attritor processing is completed in less than 60% of the attritor processing time at which the aspect ratio is maximum, a powder having a nearly spherical shape that is not sufficiently flattened remains, and surface protrusion defects of the magnetic sheet frequently occur. Therefore, the flat powder of the present invention can be produced with an attritor processing time of 60 to 95%. By the way, as described above, the shape of the powder to be processed changes with the time of the attritor processing. In less than 3 hours, a nearly spherical powder that has not been sufficiently flattened remains, and the surface protrusions of the magnetic sheet frequently occur, and in excess of 20 hours, coarse powder is formed due to entanglement and aggregation of the flat powder. Since the surface protrusions of the magnetic sheet frequently occur, the flat powder of the present invention can be produced by setting the time to 3 to 20 hours.
　続いで、扁平加工された粉末を真空又はアルゴン雰囲気で７００～９００℃で熱処理する工程が行われる。この熱処理工程はアトライタ加工により導入された扁平粉末中の格子欠陥を回復し、透磁率を改善するための工程である。ここで、熱処理雰囲気が大気や窒素であると、酸化や窒化が進み、本発明の扁平粉末が作製できない。したがって、真空もしくは不活性雰囲気での熱処理が必要であり、製造コストを考慮すると、真空又はアルゴン雰囲気により、低コストで本発明の扁平粉末の作製が可能である。 Subsequently, a step of heat-treating the flattened powder at 700 to 900 ° C. in a vacuum or argon atmosphere is performed. This heat treatment step is a step for recovering lattice defects in the flat powder introduced by attritor processing and improving the magnetic permeability. Here, when the heat treatment atmosphere is air or nitrogen, oxidation and nitridation proceed, and the flat powder of the present invention cannot be produced. Therefore, heat treatment in a vacuum or an inert atmosphere is necessary, and considering the production cost, the flat powder of the present invention can be produced at a low cost in a vacuum or an argon atmosphere.
　この熱処理工程における熱処理温度は７００～９００℃であり、好ましくは７３０℃を超え８８０℃未満、より好ましくは７５０℃を超え８５０℃未満である。本発明において、熱処理工程はアトライタ加工により導入された扁平粉末中の格子欠陥を回復し、保磁力を低下させるための工程であり、７００℃未満では保磁力の低下が十分ではなく、９００℃を超えると焼結し、これが粗大な塊となって、シート表面の突起を増加させてしまう。 The heat treatment temperature in this heat treatment step is 700 to 900 ° C., preferably more than 730 ° C. and less than 880 ° C., more preferably more than 750 ° C. and less than 850 ° C. In the present invention, the heat treatment step is a step for recovering lattice defects in the flat powder introduced by the attritor processing and lowering the coercive force, and the coercive force is not sufficiently lowered below 700 ° C., and 900 ° C. When it exceeds, it will sinter and this will become a coarse lump and will increase the protrusion of a sheet | seat surface.
　以下、本発明について実施例によって具体的に説明する。先ず、扁平粉末の作製に当たって、ガスアトマイズ法により所定の成分の粉末を作製し１５０μｍ以下に分級した。ガスアトマイズは、アルミナ製坩堝を溶解に用い、坩堝下の直径５ｍｍのノズルから合金溶湯を出湯し、これに高圧アルゴンを噴霧することで実施した。こうして得られた原料粉末をアトライタにより扁平加工した。アトライタは、ＳＵＪ２製の直径４．８ｍｍのボールを使用し、原料粉末と工業エタノールとともに攪拌容器に投入し、羽根の回転数を３００及び４５０ｒｐｍとして実施した。扁平加工後に攪拌容器から取り出した扁平粉末と工業エタノールをステンレス皿に移し、８０℃で２４時間乾燥させた。このようにして得た扁平粉末をアルゴン中で所定の温度で２時間熱処理し、各種の評価に用いた。 Hereinafter, the present invention will be specifically described with reference to examples. First, in producing the flat powder, a powder having a predetermined component was produced by a gas atomizing method and classified to 150 μm or less. Gas atomization was performed by using an alumina crucible for melting, discharging molten alloy from a nozzle having a diameter of 5 mm under the crucible, and spraying high pressure argon on the molten alloy. The raw material powder thus obtained was flattened with an attritor. The attritor used a ball with a diameter of 4.8 mm made by SUJ2, was put into a stirring container together with the raw material powder and industrial ethanol, and the blade rotation speed was 300 and 450 rpm. The flat powder taken out of the stirring vessel after flattening and industrial ethanol were transferred to a stainless steel dish and dried at 80 ° C. for 24 hours. The flat powder thus obtained was heat-treated in argon at a predetermined temperature for 2 hours and used for various evaluations.
　扁平粉末の評価として、得られた扁平粉末の平均粒径、真密度、タップ密度、酸素含有量、窒素含有量、及び保磁力を評価した。平均粒径（体積平均粒径（Ｄ５０））はレーザー回折法、真密度はガス置換法で評価した。タップ密度は、約８０ｇの扁平粉末を、容積１００ｍｌのシリンダーに充填し、落下高さ１０ｍｍのタップ回数２００の時の充填密度で評価した。保磁力は直径６ｍｍ、高さ８ｍｍの樹脂製容器に扁平粉末を充填し、この容器の高さ方向に磁化した場合と、直径方向に磁化した場合の値を測定した。なお、扁平粉末は充填された円柱の高さ方向が厚さ方向となっているため、容器の高さ方向に磁化した場合が扁平粉末の厚さ方向、容器の直径方向に磁化した場合が扁平粉末の長手方向の保磁力となる。印加磁場は１４４ｋＡ／ｍで実施した。 As the evaluation of the flat powder, the average particle size, true density, tap density, oxygen content, nitrogen content, and coercive force of the obtained flat powder were evaluated. The average particle size (volume average particle size (D50)) was evaluated by a laser diffraction method, and the true density was evaluated by a gas displacement method. The tap density was evaluated based on the packing density when about 80 g of flat powder was filled in a cylinder with a volume of 100 ml and the drop height was 10 mm and the number of taps was 200. The coercive force was measured by filling a flat container with a resin container having a diameter of 6 mm and a height of 8 mm, and magnetizing in the height direction and magnetizing in the diameter direction. In addition, since the height direction of the filled cylinder is the thickness direction, the flat powder is flattened when magnetized in the height direction of the container and flattened when magnetized in the thickness direction of the flat powder and in the diameter direction of the container. It becomes the coercive force in the longitudinal direction of the powder. The applied magnetic field was 144 kA / m.
　磁性シートの作製及び評価として、トルエンに塩素化ポリエチレンを溶解し、これに得られた扁平粉末を混合、分散した。この分散液をポリエステル樹脂に厚さ１ｍｍ程度に塗布し、常温常湿で乾燥させた。その後、１３０℃、１５ＭＰａの圧力でプレス加工し、磁性シートを得た。磁性シートのサイズは縦１５０ｍｍ、横１５０ｍｍで厚さは５０μｍである。なお、磁性シート中の扁平粉末の体積充填率はいずれも約５０％であった。このシート表面を目視で観察し、表面突起の個数を評価した。さらに、このシートを水平の板に置き、側面からの目視により、水平の板からの起伏高さをマクロ的うねりの大きさとして評価した。次に、この磁性シートを、外径７ｍｍ、内径３ｍｍのドーナツ状に切り出し、インピーダンス測定器により、室温で１ＭＨｚにおけるインピーダンス特性を測定し、その結果から透磁率（複素透磁率の実数部：μ’）を算出した。さらに、得られた磁性シートの断面を樹脂埋め研磨し、その光学顕微鏡像から「長手方向の長さ／厚さ」をランダムに５０粉末測定し、その平均をアスペクト比とした。 For production and evaluation of the magnetic sheet, chlorinated polyethylene was dissolved in toluene, and the obtained flat powder was mixed and dispersed. This dispersion was applied to a polyester resin to a thickness of about 1 mm and dried at normal temperature and humidity. Then, it pressed at 130 degreeC and the pressure of 15 Mpa, and obtained the magnetic sheet. The magnetic sheet has a length of 150 mm, a width of 150 mm, and a thickness of 50 μm. The volume filling rate of the flat powder in the magnetic sheet was about 50%. The surface of the sheet was visually observed to evaluate the number of surface protrusions. Furthermore, this sheet | seat was set | placed on the horizontal board | plate, and the undulation height from a horizontal board | plate was evaluated as a macroscopic wave | undulation magnitude | size by visual observation from the side surface. Next, this magnetic sheet was cut into a donut shape having an outer diameter of 7 mm and an inner diameter of 3 mm, and impedance characteristics at 1 MHz were measured at room temperature with an impedance measuring device. From the result, permeability (real part of complex permeability: μ ′ ) Was calculated. Further, the cross-section of the obtained magnetic sheet was resin-filled and polished, 50 powders of “length / thickness in the longitudinal direction” were randomly measured from the optical microscope image, and the average was taken as the aspect ratio.
Figure JPOXMLDOC01-appb-T000001
 　表１に示すように、Ｎｏ．５～６、１３～１４、２０～２２、２６、２８及び３０～３１は本発明例であり、Ｎｏ．１～４、７～１２、１５～１９、２３～２５、２７、２９及び３２は比較例である。
Figure JPOXMLDOC01-appb-T000001
 As shown in Table 1, no. Nos. 5 to 6, 13 to 14, 20 to 22, 26, 28 and 30 to 31 are examples of the present invention. 1 to 4, 7 to 12, 15 to 19, 23 to 25, 27, 29, and 32 are comparative examples.
　比較例Ｎｏ．１～４は最大アスペクト比が得られる時間を１００％としたときの加工時間が短く、平均粒径が小さく、真密度に対するタップ密度の比が大きく、扁平粉のアスペクト比が小さく、扁平粉の厚さが厚く、酸素含有量が少なく、長手方向の保磁力及び厚さ方向の保磁力が小さく、厚さ方向の保磁力に対する長手方向の保磁力の比が小さく、かつアトライタ加工時間が短い（Ｎｏ．３及び４を除く）ために、シート表面の突起不良が多く、かつシートの複素透過率の低下が見られた。 Comparative Example No. 1-4, the processing time when the maximum aspect ratio is obtained as 100% is short, the average particle size is small, the ratio of the tap density to the true density is large, the aspect ratio of the flat powder is small, The thickness is small, the oxygen content is small, the coercivity in the longitudinal direction and the coercivity in the thickness direction are small, the ratio of the coercivity in the longitudinal direction to the coercivity in the thickness direction is small, and the attritor processing time is short ( No. 3 and 4), there were many protrusion defects on the sheet surface, and a decrease in the complex transmittance of the sheet was observed.
　比較例Ｎｏ．７～１２は、最大アスペクト比が得られる時間を１００％としたときの加工時間、平均粒径（Ｎｏ．８～９を除く）、真密度に対するタップ密度の比、扁平粉のアスペクト比（Ｎｏ．８～１０を除く）、扁平粉の厚さ、酸素含有量、長手方向の保磁力の値、及び厚さ方向の保磁力のいずれも本発明の条件が満たされていないために、シート表面の突起不良が多く、かつＮｏ．７～１０においてはシートのマクロ的うねりが、またＮｏ．９～１２においてはシートの複素透過率の低下が見られた。 Comparative Example No. 7 to 12 are processing time when the maximum aspect ratio is obtained as 100%, average particle size (excluding No. 8 to 9), ratio of tap density to true density, aspect ratio of flat powder (No 8 to 10), the thickness of the flat powder, the oxygen content, the coercive force in the longitudinal direction, and the coercive force in the thickness direction do not satisfy the conditions of the present invention. There are many protrusion defects of No. In Nos. 7 to 10, the macro swell of the sheet In 9 to 12, a decrease in the complex transmittance of the sheet was observed.
　比較例Ｎｏ．１５～１９は、アトライタ加工時間が長く（Ｎｏ．１７及び１８）、最大アスペクト比が得られる時間を１００％としたときの加工時間が長く（Ｎｏ．１５～１８）、平均粒径が小さく（Ｎｏ．１５～１８）、真密度に対するタップ密度の比が大きく（Ｎｏ．１５～１８）、扁平粉のアスペクト比が大きく（Ｎｏ．１５）、扁平粉の厚さが薄く（Ｎｏ．１５～１８）、酸素含有量が多く（Ｎｏ．１５～１８）、長手方向の保磁力及び厚さ方向の保磁力の値がいずれも大きいために、Ｎｏ．１９を除いてシート表面の突起不良が多い。また、シートのマクロ的うねりについて、Ｎｏ．１５～１８の場合に見られ、かつシートの複素透過率の低下についても、Ｎｏ．１６～１９の場合に見られた。 Comparative Example No. Nos. 15 to 19 have a long attritor processing time (No. 17 and 18), a long processing time when the time for obtaining the maximum aspect ratio is 100% (No. 15 to 18), and a small average particle size ( No. 15 to 18), the ratio of the tap density to the true density is large (No. 15 to 18), the aspect ratio of the flat powder is large (No. 15), and the thickness of the flat powder is thin (No. 15 to 18). ), The oxygen content is large (Nos. 15 to 18), and the coercive force in the longitudinal direction and the coercive force in the thickness direction are both large. Except for 19, there are many protrusion defects on the sheet surface. Regarding the macro swell of the sheet, no. No. 15 to 18 and the reduction in the complex transmittance of the sheet is also No. It was seen in cases 16-19.
　比較例Ｎｏ．２３は、熱処理温度が高く、真密度に対するタップ密度の比が大きいため、シート表面の突起不良が多い。比較例Ｎｏ．２４及び２５は、熱処理雰囲気が大気、窒素であり、酸素含有量が多く（Ｎｏ．２４）、窒素含有量が高く、長手方向の保磁力及び厚さ方向の保磁力の値がいずれも大きいために、シートの複素透過率の低下が見られた。また、比較例Ｎｏ．２７は、最大アスペクト比が得られる時間を１００％としたときの加工時間が長く、真密度に対するタップ密度の比が小さく、扁平粉の厚さが薄く、かつ厚さ方向の保磁力に対する長手方向の保磁力の比が大きいために、シート表面の突起不良がやや見られ、マクロ的うねりが見られた。 Comparative Example No. No. 23 has a high heat treatment temperature and a large ratio of tap density to true density, so that there are many protrusion defects on the sheet surface. Comparative Example No. In Nos. 24 and 25, the heat treatment atmosphere is air and nitrogen, the oxygen content is large (No. 24), the nitrogen content is high, and the coercive force in the longitudinal direction and the coercive force in the thickness direction are both large. In addition, a decrease in the complex transmittance of the sheet was observed. Comparative Example No. 27, the processing time when the time for obtaining the maximum aspect ratio is 100% is long, the ratio of the tap density to the true density is small, the thickness of the flat powder is thin, and the longitudinal direction with respect to the coercive force in the thickness direction Since the ratio of coercive force of the sheet was large, some protrusion defects on the sheet surface were observed, and macroscopic undulation was observed.
　比較例Ｎｏ．２９は、アトライタ加工時間が長く、最大アスペクト比が得られる時間を１００％としたときの加工時間が長く、真密度に対するタップ密度の比が小さく、扁平粉の厚さが薄く、酸素含有量が多く、長手方向の保磁力及び厚さ方向の保磁力の値がいずれも大きいために、シート表面の突起不良が多く、かつシートのマクロ的うねりが見られた。また、比較例Ｎｏ．３２は、平均粒径、真密度に対するタップ密度の比、及び扁平粉のアスペクト比が小さく、扁平粉の厚さが薄く、酸素含有量及び窒素含有量が高く、長手方向の保磁力及び厚さ方向の保磁力の値がいずれも大きく、かつ厚さ方向の保磁力に対する長手方向の保磁力の比が小さいために、シート表面の突起不良とマクロ的うねりが見られ、かつシートの複素透過率の低下が見られた。 Comparative Example No. No. 29 has a long attritor processing time, a long processing time when the time for obtaining the maximum aspect ratio is 100%, a small ratio of tap density to the true density, a thin flat powder thickness, and an oxygen content of In many cases, the coercive force in the longitudinal direction and the coercive force in the thickness direction were both large, so that there were many defective projections on the sheet surface, and macro swell of the sheet was observed. Comparative Example No. 32, the average particle size, the ratio of the tap density to the true density, and the aspect ratio of the flat powder are small, the thickness of the flat powder is thin, the oxygen content and the nitrogen content are high, the coercive force and the thickness in the longitudinal direction Since the coercive force value in the direction is large and the ratio of the coercive force in the longitudinal direction to the coercive force in the thickness direction is small, poor protrusion and macro waviness are observed on the sheet surface, and the complex transmittance of the sheet Decrease was observed.
　これに対し、本発明例であるＮｏ．５～６、１３～１４、２０～２２、２６、２８及び３０～３１のいずれの場合も本発明の条件を満たすことにより、磁性シートとして用いる場合に突起不良が少なく、マクロ的うねりが見られず、かつ高い透磁率を実現できる軟磁性扁平粉末とこれを用いた高透磁率磁性シート、並びにこの軟磁性扁平粉末の製造方法を提供することができる等工業的に極めて優れた効果を奏することが分かる。 On the other hand, No. which is an example of the present invention. In any case of 5-6, 13-14, 20-22, 26, 28, and 30-31, satisfying the conditions of the present invention, there are few projection defects when used as a magnetic sheet, and macro swell is seen. In addition, it is possible to provide a soft magnetic flat powder capable of realizing a high magnetic permeability, a high magnetic permeability magnetic sheet using the same, and a method for producing the soft magnetic flat powder, and exhibiting extremely excellent industrial effects. I understand.

Claims (4)

  1. 　シート表面の平滑性に優れ高透磁率を有する磁性シート用軟磁性扁平粉末であって、該軟磁性扁平粉末が軟磁性粉末を扁平化処理することにより得られたものであり、該軟磁性扁平粉末は、
    　平均粒径が４０～５３μｍであり、
    　真密度に対するタップ密度の比が０．２０～０．２３であり、
    　平均アスペクト比が１０～４０であり、
    　平均厚さが１．６～３．１μｍであり、
    　酸素含有量が０．１６～０．４８質量％であり、
    　窒素含有量が１０～２５０ｐｐｍである、軟磁性扁平粉末。     A soft magnetic flat powder for a magnetic sheet having excellent sheet surface smoothness and high permeability, wherein the soft magnetic flat powder is obtained by flattening the soft magnetic powder. Powder
    The average particle size is 40-53 μm,
    The ratio of tap density to true density is 0.20 to 0.23,
    The average aspect ratio is 10-40,
    The average thickness is 1.6 to 3.1 μm,
    The oxygen content is 0.16-0.48 mass%,
    A soft magnetic flat powder having a nitrogen content of 10 to 250 ppm.
  2. 　扁平粉末の長手方向に磁場を印加して測定した保磁力が４８～１０４Ａ／ｍであり、
    　扁平粉末の厚さ方向に磁場を印加して測定した保磁力が１２８～２００Ａ／ｍであり、
    　扁平粉末の長手方向に磁場を印加して測定した保磁力に対する扁平粉末の厚さ方向に磁場を印加して測定した保磁力の比が１．５～３．０である、請求項１に記載の軟磁性扁平粉末。     The coercive force measured by applying a magnetic field in the longitudinal direction of the flat powder is 48 to 104 A / m,
    The coercivity measured by applying a magnetic field in the thickness direction of the flat powder is 128 to 200 A / m,
    The ratio of the coercive force measured by applying a magnetic field in the thickness direction of the flat powder to the coercive force measured by applying a magnetic field in the longitudinal direction of the flat powder is 1.5 to 3.0. Soft magnetic flat powder.
  3. 　請求項１又は２に記載の軟磁性扁平粉末を含有する、シート表面の平滑性に優れ高透磁率を有する磁性シート。 A magnetic sheet comprising the soft magnetic flat powder according to claim 1 or 2 and having excellent sheet surface smoothness and high magnetic permeability.
  4. 　請求項１又は２に記載の軟磁性扁平粉末の製造方法であって、
    　ガスアトマイズ法又はディスクアトマイズ法により原料粉末を作製する工程と、
    　前記原料粉末のアスペクト比が最大となる加工時間の６０～９５％の時間で、かつ３～２０時間でアトライタ加工を完了する扁平加工工程と、
    　前記扁平加工された粉末を真空又はアルゴン雰囲気で７００～９００℃で熱処理する工程と、
    を含む、方法。     A method for producing a soft magnetic flat powder according to claim 1 or 2,
    Producing raw material powder by gas atomization method or disk atomization method;
    A flat processing step of completing attritor processing in 3 to 20 hours in a time of 60 to 95% of the processing time in which the aspect ratio of the raw material powder is maximized;
    Heat treating the flattened powder in a vacuum or argon atmosphere at 700-900 ° C .;
    Including the method.
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