WO2005069712A1 - 木質系電波吸収材 - Google Patents
木質系電波吸収材 Download PDFInfo
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- WO2005069712A1 WO2005069712A1 PCT/JP2004/018998 JP2004018998W WO2005069712A1 WO 2005069712 A1 WO2005069712 A1 WO 2005069712A1 JP 2004018998 W JP2004018998 W JP 2004018998W WO 2005069712 A1 WO2005069712 A1 WO 2005069712A1
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- Prior art keywords
- powder
- magnetic
- radio wave
- stainless steel
- wood
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- 239000006096 absorbing agent Substances 0.000 title claims abstract description 23
- 230000005291 magnetic effect Effects 0.000 claims abstract description 93
- 239000000843 powder Substances 0.000 claims abstract description 86
- 238000010521 absorption reaction Methods 0.000 claims abstract description 61
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 55
- 239000002023 wood Substances 0.000 claims abstract description 52
- 239000010935 stainless steel Substances 0.000 claims abstract description 48
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 48
- 239000000853 adhesive Substances 0.000 claims description 19
- 230000001070 adhesive effect Effects 0.000 claims description 19
- 239000011358 absorbing material Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 5
- 229910018605 Ni—Zn Inorganic materials 0.000 claims description 4
- 238000003825 pressing Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 29
- 238000005259 measurement Methods 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 239000004566 building material Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000000378 calcium silicate Substances 0.000 description 3
- 229910052918 calcium silicate Inorganic materials 0.000 description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
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- 229920001971 elastomer Polymers 0.000 description 3
- 239000011094 fiberboard Substances 0.000 description 3
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- 239000000696 magnetic material Substances 0.000 description 3
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- 229920005989 resin Polymers 0.000 description 3
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- 239000005060 rubber Substances 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
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- 239000000835 fiber Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 description 1
- 229920001651 Cyanoacrylate Polymers 0.000 description 1
- 208000032368 Device malfunction Diseases 0.000 description 1
- MWCLLHOVUTZFKS-UHFFFAOYSA-N Methyl cyanoacrylate Chemical compound COC(=O)C(=C)C#N MWCLLHOVUTZFKS-UHFFFAOYSA-N 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
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- 239000003989 dielectric material Substances 0.000 description 1
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- 230000005684 electric field Effects 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 239000012784 inorganic fiber Substances 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
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- 230000001788 irregular Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000000474 nursing effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
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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
- H01F1/0027—Thick magnetic films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B23/00—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose
- B32B23/04—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
- E04C2/02—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials
- E04C2/26—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials composed of materials covered by two or more of groups E04C2/04, E04C2/08, E04C2/10 or of materials covered by one of these groups with a material not specified in one of the groups
- E04C2/284—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials composed of materials covered by two or more of groups E04C2/04, E04C2/08, E04C2/10 or of materials covered by one of these groups with a material not specified in one of the groups at least one of the materials being insulating
-
- 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
-
- 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
- H01F1/34—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 non-metallic substances, e.g. ferrites
- H01F1/36—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 non-metallic substances, e.g. ferrites in the form of particles
- H01F1/37—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 non-metallic substances, e.g. ferrites in the form of particles in a bonding agent
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/008—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with a particular shape
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
- Y10T428/12771—Transition metal-base component
- Y10T428/12861—Group VIII or IB metal-base component
- Y10T428/12951—Fe-base component
- Y10T428/12958—Next to Fe-base component
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
- Y10T428/2852—Adhesive compositions
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31971—Of carbohydrate
- Y10T428/31989—Of wood
Definitions
- the present invention relates to a wood-based radio wave absorbing material having excellent performance of absorbing radio waves in a frequency band of several GHz, such as a cellular phone, and capable of easily adjusting the performance.
- Ferrite and carbon are mainly used as a dielectric loss material and a conductive loss material of a radio wave absorber in a frequency range of 10 MHz to 1 GHz. At 1 GHz or higher, conductive metal plates, metal nets, metal fibers, etc. are used. These materials are usually used as a sheet-like radio wave absorber formed by composite with plastic or rubber.
- Patent Document 1 Magnetoplanite-type hexagonal ferrite powder mixed with a holding material composed of an inorganic material such as rubber, resin, or calcium silicate (Patent Document 2), Fe-based alloy containing 35 to 35% by weight of Cr Soft magnetic powder composed of rubber or resin (Patent Document 3), soft magnetic flaky powder composed of stainless steel SUS430 mixed and dispersed in synthetic resin (Patent Document 4), inorganic fiber (Patent Document 5) and the like, which contain a resin binder, a conductive or magnetic fiber or powder, and have a porosity of 35 to 89%.
- Patent Document 2 Magnetoplanite-type hexagonal ferrite powder mixed with a holding material composed of an inorganic material such as rubber, resin, or calcium silicate
- Patent Document 3 Fe-based alloy containing 35 to 35% by weight of Cr
- Patent Document 4 soft magnetic flaky powder composed of stainless steel SUS430 mixed and dispersed in synthetic resin
- Patent Document 5 inorganic fiber
- radio wave absorber using general building materials, gypsum, asbestos cement or calcium silicate is mainly used, and carbon powder, ferrite powder, metal powder, metal compound powder or a mixture thereof, which is an electromagnetic wave loss material, is used.
- an electromagnetic wave absorbing inner wall material for the 70MHz-3GHz band contained therein Patent Document 6
- Patent Document 7 a material obtained by bonding a wood material using a fine electromagnetic wave shielding material in combination with an adhesive
- Patent Documents 8, 9, and 10 are known.
- the present inventor has previously developed magnetic wood as a new U ⁇ building material having functions such as magnetic attraction and radio wave shielding (Patent Document 11, Non-Patent Documents 13).
- Patent Document 1 Japanese Patent Application Laid-Open No. Hei 9 283971
- Patent Document 2 Japanese Patent Application Laid-Open No. 11 354972
- Patent Document 3 Japanese Patent Application Laid-Open No. 2000-200990
- Patent Document 4 JP 2001-274587 A
- Patent Document 5 JP-A-2003-60381
- Patent Document 6 JP-A-6-209180
- Patent Document 7 JP-A-61-269399
- Patent Document 8 Japanese Patent Application Laid-Open No. 01-191500
- Patent Document 9 Japanese Patent Publication No. 6-82943
- Patent Document 10 Japanese Patent Publication No. 6-85472
- Patent Document 11 JP 2001-118711 A
- Non-Patent Document 1 Oka: Basic Properties of Magnetic Wood, Journal of the Japan Society of Applied Magnetics,
- Non-Patent Document 2 “Journal of Applied Physics” Vol.91, No.10, Parts2 and
- Non-Patent Document 3 ⁇ New Engineer J 29, June, p. 20 (2002)
- a radio wave absorbing material in a building a metal plate, a metal foil, or a metal mesh having radio wave shielding properties is attached to a ceiling, an inner wall, a floor, a partition, or the like of a room or area where radio wave absorption is required. Or the method of applying metal-containing paint is adopted
- the metal plate exhibits perfect reflection and zero transmission characteristics with respect to electromagnetic waves, and it is difficult to adjust the electromagnetic wave absorption characteristics of the indoor space.
- Conventional electromagnetic wave absorbers for general building materials have various problems, such as high specific gravity, workability, workability, and price, for which ceramics and cement boards have been developed.
- Patent Documents 7-10 a radio-absorbing wood material suitable as a building material has been developed, but the one described in Patent Document 7 is intended for a frequency of 50-500 MHz, and is described in Patent Document 8 Are for frequencies between 30 kHz and 1 GHz, and those described in Patent Documents 9 and 10 Numbers 10 to 50MHz!
- radio wave absorbers such as the above-mentioned conventional technology have been developed as radio wave absorbers corresponding to the GHz band that absorb these unnecessary radio waves.
- the parameters for obtaining optimal radio wave absorption characteristics are as follows. Only the shape and content of the dielectric material and conductive material mixed in the holding material exerted little flexibility. Furthermore, most conventional radio wave absorbers targeting these frequency bands only target a single frequency. Recent wireless LANs have two frequency bands, the 2.45 GHz band and the 5.2 GHz band. There is also a need for a radio wave absorber that can simultaneously handle unnecessary radio waves in multiple bands.
- One of the magnetic woods to which the present inventors have imparted magnetic properties which has been imparted with magnetic properties, has a thickness of about lcm and is made of a mixture of ferrite powder and an adhesive.
- Wood materials sandwiched in a shape have both the characteristics of wooden materials and the function of absorbing radio waves, and therefore have attracted attention as materials that can be used as they are as radio wave absorbers.
- radio wave absorbers In addition to the radio wave absorption function, magnetic wood can provide low specific gravity, 'easiness of processing, woodiness such as warmth, sound absorption, humidity control, and heat insulation. Mobile phones can no longer be used in music halls, restaurants and hospitals that use this magnetic wood for interior walls.
- the magnetic wood developed by the present inventors uses the magnetic loss of a magnetic material such as Mn-Zn ferrite, and the radio wave absorption capacity is adjusted by adjusting the thickness of the magnetic layer and the content of the magnetic material. 2.
- the amount of radio wave absorption in the 45 GHz band is about 7 dB, which further enhances the radio wave absorption capacity in the required band within the wireless LAN and ISM frequency bands, It was necessary to increase the degree of freedom.
- the inventor of the present invention in the course of repeating experiments on the use of other magnetic powders and conductive powders, including the mixing ratio of ferrite powders and the thickness of the magnetic layer, combined non-magnetic ferrite powders with ferrite powders. By using stainless steel powder, it is possible to obtain a wood-based radio wave absorber that has more excellent radio wave absorption characteristics in wireless LAN and ISM frequency bands and that can easily adjust the required absorption capacity in the required band. Was found.
- the present invention provides: (1) a laminated type comprising a magnetic layer formed by press-bonding opposing plate members made of natural wood or processed wood material via an adhesive containing ferrite powder;
- the magnetic wood contains 20 to 80% by volume of non-magnetic stainless steel powder with respect to ferrite powder, and the total volume content of the ferrite powder and the non-magnetic stainless steel powder in the magnetic layer is increased. 10-40%, the thickness of the magnetic layer is 0.5-5. Omm, the center frequency is within 18GHz, and the radio wave absorption of 10dB or more in the frequency 2.45GHz band or 5.2GHz band A wood-based radio wave absorbing material having characteristics.
- the present invention provides (2) the wood-based radio wave absorbing material (1), wherein the ferrite powder is Mn-Zn-based ferrite, and the nonmagnetic stainless steel powder is SUS304 stainless steel. It is.
- the present invention provides the above (2), wherein the (3) ferrite powder is a mixture of Mn—Zn ferrite: Ni—Zn ferrite at a weight ratio of S 1: 4—4: 1. It is a wooden radio wave absorber.
- the radio wave absorption characteristics can be adjusted by controlling the volume content of the ferrite powder, the thickness of the magnetic layer, and the mixing ratio of the ferrite powder and the nonmagnetic stainless steel powder.
- Figure 1 shows the design parameters of the radio wave absorption characteristics of the radio wave absorber. The center frequency (f), the maximum absorption (Smax) at the center frequency (f), and the half width AW (- 6dB)
- the peak of the maximum absorption (Smax) of the radio wave absorption characteristic shifts to a low frequency band with an increase in the thickness of the magnetic layer.
- the center frequency (f) of the radio wave absorption characteristics is
- the total volume content of iron powder and non-magnetic stainless steel powder increases, a large shift can be achieved by changing the internal ratio (non-magnetic stainless steel powder: ferrite powder) and magnetic layer thickness.
- the electromagnetic wave absorption characteristics have high sharpness in the low frequency region by increasing the thickness of the magnetic layer and reducing the total volume content of ferrite powder and non-magnetic stainless steel powder.
- the radio wave absorption characteristics can be high and sharp in a low frequency region by increasing the thickness of the magnetic layer and increasing the ratio of the nonmagnetic stainless steel powder in the magnetic layer.
- Magnetic loss is important when magnetic wood is applied to radio wave absorption. Wood itself is a dielectric and transmits radio waves. When a radio wave generated by an electric field and a magnetic field hits wood when the magnetic layer is sandwiched between opposing wood plates, the magnetic layer disappears due to the magnetic loss characteristics of the magnetic layer and is converted into heat and absorbed. You. Ferrite is preferable as the magnetic material constituting the magnetic wood, but ferrite is a low-loss material.
- Non-magnetic stainless steel is non-magnetic, unlike soft magnetic stainless steel, which is commonly used as a force-absorbing material, which is a conductive material.
- non-magnetic stainless steel has a lower conductivity (1.3 X 10 4 [/ Q] than other metals having high conductivity, for example, copper (5.8 ⁇ 10 7 [/ ⁇ ⁇ ⁇ ]). -m]), the complex imaginary part '' does not increase.
- a non-magnetic stainless steel powder in combination it is possible to obtain radio wave absorption characteristics that cannot be obtained by using only ferrite powder.
- copper is easily unsuitable for wood having hygroscopicity because it is easily oxidized.
- SUS304 stainless steel has excellent corrosion resistance.
- the wood-based material itself can have excellent radio wave absorption characteristics, it can be used as a building material without adding a radio wave absorber to conventional general building materials and wood products. As a result, desired radio wave absorption characteristics can be obtained. Also, by adjusting the ratio of the nonmagnetic stainless steel powder added to the magnetic layer and the thickness of the magnetic layer, the absorption band, the size of the absorption peak, and the half width can be controlled, so that the degree of freedom in designing the electromagnetic wave absorbing material is increased. By simply adjusting the thickness of the magnetic layer and the ratio of nonmagnetic stainless steel powder added to the magnetic layer, radio wave absorbers corresponding to the 2.45 GHz band and the 5.2 GHz band can be easily manufactured.
- an adhesive mixed with ferrite powder is disposed between two opposing boards made of natural wood or processed wood. Sheet It is produced by pressing and drying the plate.
- the thickness of the wood is preferably about 2-3 mm.
- Examples of the ferrite powder include Mn-Zn ferrite and Ni-Zn ferrite.
- the size of the ferrite powder is preferably about 50 to 60 m in terms of the center particle diameter, and about 45 to 75 / z m in the particle diameter range.
- the Mn-Zn ferrite and the Ni-Zn ferrite may be used alone, but the frequency at which the maximum value of the radio wave absorption is maximized can be shifted by using a mixture of the two types. As the mixing ratio of Mn Zn ferrite increases, the frequency at which the maximum value of the radio wave absorption is shifted to a lower frequency while the radio wave absorption is maintained at a high level.
- the adhesive may be of any type as long as it has an adhesive strength sufficient to adhere wood.
- it may be selected from various types such as a phenolic resin, a urethane resin, an acrylic resin, a cyanoacrylate, and an epoxy resin.
- the higher the mixing ratio of the ferrite powder mixed in the adhesive the higher the laminated magnetic wood has a radio wave absorption function.
- the mixing ratio is too high, sufficient adhesive strength cannot be obtained. For this reason, there is a risk that at least two wooden boards constituting the laminated magnetic wood will peel off. Therefore, the mixing ratio of the ferrite powder mixed in the adhesive must be such that the adhesive strength is not impaired.
- an adhesive mixed with ferrite powder is applied between two opposing wooden boards.
- the adhesive is preferably applied in a uniform thickness so that there is no difference in the radio wave absorption function and mass depending on the part of the laminated magnetic wood.
- the two wooden boards are pressed and then the adhesive is dried to complete the laminated magnetic wood.
- the crimping is performed so that the thickness becomes uniform so that the radio wave absorbing function and the mass do not differ depending on the portion of the laminated magnetic wood.
- the plate material in the present invention does not necessarily have to be a flat plate.
- Various types such as curved plates, thicker blocks, irregular shapes with protrusions and grooves, etc.
- the non-magnetic stainless steel powder is contained at a volume ratio of 20 to 80%, more preferably 30 to 50% with respect to the ferrite powder, so that the frequency 2.4-1 2. In the 5GHz ISM frequency band, it should have radio absorption characteristics with a maximum absorption of 10dB or more, more preferably 20dB or more.
- Stainless steel containing about 4 wt% or more of Ni and about 12-30 wt% of Cr is known as nonmagnetic stainless steel.
- a typical nonmagnetic stainless steel is SUS304 (chromium nickel-based stainless steel: about 18 wt% Cr). ,about
- the size of the nonmagnetic stainless steel powder is preferably about 80 to 100 ⁇ m in terms of the central particle size.
- the total volume content of the magnetic powder and the non-magnetic stainless steel powder in the magnetic layer formed after the solidification of the adhesive is 10 to 40%, more preferably 10 to 30%.
- the thickness of the magnetic layer is more preferably 1.0 to 4.0 mm because a sufficiently large amount of radio wave absorption can be obtained with a force of 4.0 mm selected in a range of 0.5 to 5.0 mm.
- V Ferrite s: Stainless steel
- the radio wave absorption characteristics were measured by mixing ferrite powder and stainless steel powder with an adhesive. After sandwiching and drying between two fiberboards to produce a laminated magnetic wood sample, the sample was separated into a magnetic layer and a wood layer, and as shown in Fig. The sample was processed into an annular shape with a thickness of 00 mm and an outer diameter of 7. OO mm and a thickness of h mm. It was measured. Table 2 shows the conditions for measuring and calculating the electromagnetic wave absorption characteristics. The material properties of the fiberboard are invariant with respect to the measurement frequency for both the complex permittivity and the complex permeability.
- FIG. 4 (A) and 4 (B) show the measurement results of radio wave absorption in the measurement frequency range of 0.05 to 12GHz. Fly powder only (20F), stainless steel powder ratio 40
- radio wave absorption of about 30dB and 25dB was obtained at about 7GHz and 6GHz, respectively.
- the internal ratio (S: F) of the fly powder and the stainless steel powder is 2: 3, and the thicknesses of the magnetic layers are 0.5 mm, 1. Omm, 1.5 mm, 2. Omm, and 4. Omm, respectively.
- a laminated magnetic wood sample was prepared under the same conditions as in row f 1, except that Figure 5 shows the measurement results of radio wave absorption in the measurement frequency range of 0.05 to 12 GHz. At a magnetic layer thickness of 1.5 mm, a maximum radio wave absorption of about 30 dB was obtained at about 4.5 GHz. It can be seen that the center frequency shifts to a lower frequency band with an increase in the thickness of the magnetic layer. Also, it can be seen that when the internal ratio of the stainless steel powder is low, the thinner the magnetic layer, the higher the radio wave absorption.
- Table 3 shows the measurement results of the above examples as the center frequency f, the maximum absorption Smax, and the half width ⁇
- FIG. 7 shows the volume ratios of the ferrite powder and the non-magnetic stainless steel powder for the total volume content of the ferrite powder and the non-magnetic stainless steel powder in the magnetic layer of 10 Vol%, 20 Vol%, and 30 Vol%, respectively.
- the distribution of the radio wave absorption characteristics depending on the thickness of the magnetic layer is indicated by shading. A relatively high maximum absorption was distributed on the concentric circles centered on the lower right point of the distribution diagram, and the radius of the concentric circles tended to increase as the volume content increased.
- Vs 20Vol%
- ferrite powder 2: 3
- magnetic layer thickness 4 4.
- the center frequency f [ GHz] o was 2.62
- maximum absorption Smax [dB] was 45.18
- half-value width AW [GHz] was 0.120 or less.
- the wooden radio wave absorber of the present invention has a function as a wood material and has excellent radio wave absorption characteristics. Therefore, (a) a music hall, a restaurant, a hospital, a nursing facility, a wooden building, a school, etc. By using as building materials (wood wall material, ceiling material, wood door material, floor material, partition), (b) security function materials for information appliances, (c) furniture, (d) office supplies, stationery, etc. Radio interference can be prevented, unnecessary radio waves can be reduced, and the living environment can be improved.
- FIG. 1 is a graph showing design parameters of a radio wave absorber.
- FIG. 2 Front and side views showing the shape and dimensions of an annular sample for measuring radio wave absorption characteristics ( (A) and a sectional view (B) showing a state in which an annular sample is sandwiched between sample holders.
- FIG. 3 is a graph showing the radio wave absorption characteristics of each sample of Example 1.
- FIG. 4 is a graph showing the radio wave absorption characteristics of each sample of Example 2.
- FIG. 5 is a graph showing the radio wave absorption characteristics of each sample of Example 3.
- FIG. 6 is a graph showing the radio wave absorption characteristics of each sample of Example 4.
- FIG. 7 is a distribution diagram of radio wave absorption characteristics of samples of an example and a comparative example.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Architecture (AREA)
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Hard Magnetic Materials (AREA)
- Soft Magnetic Materials (AREA)
- Building Environments (AREA)
- Aerials With Secondary Devices (AREA)
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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JP2005516979A JP4298706B2 (ja) | 2004-01-19 | 2004-12-20 | 木質系電波吸収建材 |
US10/586,471 US7544427B2 (en) | 2004-01-19 | 2004-12-20 | Woody electric-wave-absorbing building material |
GB0614346A GB2430078B (en) | 2004-01-19 | 2004-12-20 | Woody electric wave absorber |
CA 2559382 CA2559382A1 (en) | 2004-01-19 | 2004-12-20 | Woody electric wave absorber |
Applications Claiming Priority (2)
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JP2004011249 | 2004-01-19 | ||
JP2004-011249 | 2004-01-19 |
Publications (1)
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WO2005069712A1 true WO2005069712A1 (ja) | 2005-07-28 |
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PCT/JP2004/018998 WO2005069712A1 (ja) | 2004-01-19 | 2004-12-20 | 木質系電波吸収材 |
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US (1) | US7544427B2 (ja) |
JP (1) | JP4298706B2 (ja) |
CN (1) | CN1906989A (ja) |
CA (1) | CA2559382A1 (ja) |
GB (1) | GB2430078B (ja) |
TW (1) | TW200525558A (ja) |
WO (1) | WO2005069712A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007134466A (ja) * | 2005-11-09 | 2007-05-31 | Iwate Univ | 木質系電波吸収ボード |
JP2007245419A (ja) * | 2006-03-14 | 2007-09-27 | Iwate Univ | 磁性木材 |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070037204A1 (en) * | 2003-08-08 | 2007-02-15 | Hiroyuki ABURANTAI | Gene overexpressed in cancer |
CN106205937A (zh) * | 2016-08-17 | 2016-12-07 | 安徽德信电气有限公司 | 一种高效软磁铁氧体磁芯材料 |
TWI783148B (zh) * | 2018-06-04 | 2022-11-11 | 日商麥克賽爾股份有限公司 | 電磁波吸收體 |
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- 2004-12-20 JP JP2005516979A patent/JP4298706B2/ja not_active Expired - Fee Related
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JP2007245419A (ja) * | 2006-03-14 | 2007-09-27 | Iwate Univ | 磁性木材 |
Also Published As
Publication number | Publication date |
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GB2430078A8 (en) | 2007-03-23 |
CN1906989A (zh) | 2007-01-31 |
GB2430078B (en) | 2008-04-16 |
GB0614346D0 (en) | 2006-08-30 |
JP4298706B2 (ja) | 2009-07-22 |
US20070164893A1 (en) | 2007-07-19 |
JPWO2005069712A1 (ja) | 2008-04-17 |
TW200525558A (en) | 2005-08-01 |
US7544427B2 (en) | 2009-06-09 |
CA2559382A1 (en) | 2005-07-28 |
GB2430078A (en) | 2007-03-14 |
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