JP2019176143A - Resin molding - Google Patents

Abstract

To provide a resin molding having an excellent electromagnetic wave shield performance over a wide frequency band.SOLUTION: A resin molding 1 comprises a first layer 2, and a second layer 3 laminated on the first layer 2. The first layer 2 contains a first thermoplastic resin and a magnetic material, and the second layer 3 contains a second thermoplastic resin and an electric conductive material different from the magnetic material of the first layer 2. In the resin molding 1, a magnetic field shield performance in a frequency of 1 MHz to 100 MHz of the resin molding 1 is 6 dB or more, and an electric field shield performance in a frequency of 0.1 GHz to 10 GHz of the resin molding 1 is 20 dB or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin molded body.

  Conventionally, in devices that generate electromagnetic noise due to operation, multi-information displays such as car navigation systems and smart meters, in-vehicle cameras, in-vehicle ECUs and other chassis of electronic devices, and chassis that are close to the board, to improve electromagnetic shielding In addition, electromagnetic shielding performance-added products such as metal plates, plating, electromagnetic wave shielding sheets, and painting are used.

  Patent Document 1 below discloses an electromagnetic wave shielding sheet in which a magnetically permeable layer is laminated on at least one surface of a conductive layer. The conductive layer is said to be obtained by dispersing 0.5 to 5.0 volume% of stainless steel fibers having a diameter of 7 to 15 μm and a length of 0.2 to 3 mm as a conductive filler in a synthetic resin. The magnetically permeable layer is said to be obtained by dispersing 10 to 70% by volume of a highly permeable filler in a synthetic resin.

  Patent Document 2 below discloses an electromagnetic wave noise suppression sheet having a base material, a conductive layer, and a magnetic layer. The conductive layer is formed by applying a conductive coating material. The magnetic layer is formed by applying a magnetic coating material. Patent Document 2 describes that a metal or alloy such as Cu, Au, or Al, carbon, or the like is used as a material for the conductive layer.

  Patent Document 3 below describes a composite molded body in which a metal molded portion and a resin molded portion are heat-sealed and integrated by two-color injection molding. The metal forming part is formed of a metal material in which an additive having electromagnetic wave shielding performance is mixed and dispersed. The resin molded part is formed of a thermoplastic resin material in which an additive different from the additive mixed and dispersed in the metal molded part is mixed and dispersed.

Japanese Patent No. 2518626 JP 2010-153542 A JP 2014-156100 A

  In recent years, electromagnetic shielding performance in a wide frequency range from the MHz band to the GHz band has been demanded due to the increase in the number of devices that generate electromagnetic noise and the problem of device malfunction due to external noise.

  On the other hand, when the sheet | seat and molded object of patent documents 1-3 are used, there exists a problem of an increase in a process man-hour and cost increase. Moreover, when a metal filler is used to impart conductivity, there is a problem that it is difficult to reduce the weight. Furthermore, when a non-metallic filler is used instead of the metallic filler, there is a problem that a shielding effect at a high frequency cannot be obtained sufficiently.

  The objective of this invention is providing the resin molding which is excellent in electromagnetic wave shielding performance over a wide frequency band.

  The resin molded body according to the present invention is a resin molded body comprising a first layer and a second layer laminated on the first layer, wherein the first layer is a first layer. A magnetic field at a frequency of 1 MHz to 100 MHz of the resin molding includes a thermoplastic resin and a magnetic material, and the second layer includes a second thermoplastic resin and a conductive material different from the magnetic material. The shielding performance is 6 dB or more, and the electric field shielding performance of the resin molded body at a frequency of 0.1 GHz to 10 GHz is 20 dB or more.

  In a specific aspect of the resin molded body according to the present invention, the real part μ ′ of the complex relative permeability at a frequency of 10 MHz of the first layer is 3 or more.

  On the other specific situation of the resin molding which concerns on this invention, content of the said magnetic material with respect to 100 weight part of said 1st thermoplastic resins is 80 weight part or more.

In still another specific aspect of the resin molded body according to the present invention, the surface resistivity of the second layer is less than 10 ² Ω / sq.

  In still another specific aspect of the resin molded body according to the present invention, the conductive material is at least one carbon material selected from the group consisting of graphite, carbon black, and carbon nanotubes.

  In still another specific aspect of the resin molded body according to the present invention, the conductive material includes a first conductive material having a particle size or fiber length of 5 μm or more, and a particle size or fiber length of 1 μm or less. A second conductive material. Preferably, the content of the first conductive material with respect to 100 parts by weight of the second thermoplastic resin is 65 parts by weight or more and 230 parts by weight or less, and the content with respect to 100 parts by weight of the second thermoplastic resin. The content of the second conductive material is 5 parts by weight or more and 70 parts by weight or less.

  In still another specific aspect of the resin molded body according to the present invention, the content of the conductive material with respect to 100 parts by weight of the second thermoplastic resin is 80 parts by weight or more.

In still another specific aspect of the resin molded body according to the present invention, the density of the resin molded body is 4.0 g / cm ³ or less.

  In still another specific aspect of the resin molded body according to the present invention, the resin molded body is an injection-molded body, and the first layer and the second layer are integrally molded.

  In still another specific aspect of the resin molded body according to the present invention, a transmission attenuation rate when the first layer of the resin molded body is measured in close contact with a transmission line by a microstrip line method has a frequency of 10 MHz. Is 5 dB or more.

  ADVANTAGE OF THE INVENTION According to this invention, the resin molding which is excellent in electromagnetic wave shielding performance over a wide frequency band can be provided.

It is typical sectional drawing which shows the resin molding which concerns on one Embodiment of this invention.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a resin molded body according to an embodiment of the present invention. As shown in FIG. 1, the resin molded body 1 includes a first layer 2 and a second layer 3. On the main surface 2a of the first layer 2, the second layer 3 is laminated.

  Thus, the laminated body of this invention is equipped with a 1st layer and a 2nd layer laminated | stacked on the 1st layer. In addition, the laminated body of this invention is not limited to said embodiment, as long as it has a 1st layer and a 2nd layer.

  In the present invention, the first layer includes a first thermoplastic resin and a magnetic material. The second layer includes a second thermoplastic resin and a conductive material different from the magnetic material. The magnetic shielding performance of the resin molded body at a frequency of 1 MHz to 100 MHz is 6 dB or more. Moreover, the electric field shielding performance in the frequency of 0.1 GHz-10 GHz of the resin molding 1 is 20 dB or more.

  The magnetic field shielding performance at a frequency of 1 MHz to 100 MHz can be measured by, for example, the KEC (KEC: abbreviation for “Kansai Electronics Industry Promotion Center”) method. The magnetic field shield performance at a frequency of 1 MHz to 100 MHz may be obtained by measuring one point of the magnetic field shield performance at a frequency of 10 MHz.

  In addition, the electric field shielding performance at 0.1 GHz to 1 GHz can be measured by, for example, the KEC method, and the electric field shielding performance at 1 GHz to 10 GHz can be measured by, for example, a dual-focus flat cavity (DFFC) method. Can be measured. The electric field shielding performance at a frequency of 0.1 GHz to 1 GHz may be obtained by measuring one point of the electric field shielding performance at a frequency of 1 GHz.

  The resin molded body of the present invention simultaneously includes a first layer containing a magnetic material having electromagnetic wave absorption performance in a low frequency band and a second layer containing a conductive material having electromagnetic wave shielding performance in a high frequency band. Therefore, the electromagnetic wave shielding performance is excellent over a wide frequency band of frequencies from 1 MHz to 10 GHz. Moreover, since the resin molding of this invention contains the magnetic material and the electroconductive material in a different resin layer, content of each material can be raised and high electromagnetic shielding performance can be implement | achieved.

  In the present invention, the magnetic field shielding performance at a frequency of 1 MHz to 100 MHz is preferably 6 dB or more, more preferably 8 dB or more, and further preferably 10 dB or more. Moreover, the upper limit value of the magnetic field shielding performance at a frequency of 1 MHz to 100 MHz is not particularly limited, but can be set to, for example, 60 dB.

  In the present invention, the electric field shielding performance at a frequency of 0.1 GHz to 10 GHz is preferably 20 dB or more, more preferably 30 dB or more, and further preferably 40 dB or more. Moreover, the upper limit value of the electric field shielding performance at a frequency of 0.1 GHz to 10 GHz is not particularly limited, but can be set to, for example, 80 dB.

  In the present invention, the real part μ ′ of the complex relative permeability at a frequency of 10 MHz of the first layer containing the magnetic material is preferably 3 or more, more preferably 5 or more. When the real part μ ′ of the complex relative permeability at the frequency of 10 MHz of the first layer is equal to or higher than the lower limit, the loss at the time of electromagnetic wave absorption is further increased, and the electromagnetic wave shielding performance can be further improved. The upper limit value of the real part μ ′ of the complex relative permeability at a frequency of 10 MHz of the first layer is not particularly limited, but can be set to 100, for example. Further, the complex relative permeability, which is an index of magnetic material characteristics, can be measured using, for example, a material impedance analyzer.

In the present invention, the surface resistivity of the second layer containing a conductive material is preferably less than 10 ² Ω / sq, more preferably less than 10 ¹ Ω / sq. When the surface resistivity of the second layer is less than the above upper limit, the loss during electromagnetic wave reflection is further increased, and therefore the electromagnetic wave shielding performance can be further enhanced. The lower limit value of the surface resistivity of the second layer is not particularly limited, but can be set to 10 ⁻³ Ω / sq, for example. Moreover, the surface resistivity which is an electroconductive parameter | index can be measured using a low resistivity meter, for example.

In the present invention, the density of the resin molded body including the first layer and the second layer is preferably 4.0 g / cm ³ or less, more preferably 3.5 g / cm ³ or less. When the density of the resin molding is not more than the above upper limit, the weight reduction effect can be further enhanced. In addition, the lower limit value of the density of the resin molded body is not particularly limited, but may be, for example, 1.5 g / cm ³ . Moreover, the density of the resin molding can be measured by, for example, an underwater substitution method.

  In addition, in the resin molding of this invention, since the 1st layer and the 2nd layer are comprised with the thermoplastic resin, weight reduction can be achieved. Moreover, when a conductive material is the carbon material mentioned later, further weight reduction can be achieved.

  In the present invention, the transmission attenuation factor when the first layer of the resin molded body is measured in close contact with the transmission path by the microstrip line method in accordance with IEC62333-2 is preferably 5 dB or more at a frequency of 10 MHz, more preferably. Is 8 dB or more.

  In the present invention, the thickness of the first layer is not particularly limited, but can be, for example, 0.5 mm or more and 3.0 mm or less. Moreover, the thickness of the second layer can be, for example, not less than 0.5 mm and not more than 4.0 mm.

  Hereinafter, the detail of the material which comprises the resin molding of this invention is demonstrated.

(First layer)
A first thermoplastic resin;
It does not specifically limit as a 1st thermoplastic resin, A well-known thermoplastic resin can be used. Specific examples of the first thermoplastic resin include polyolefin, polystyrene, polyacrylate, polymethacrylate, polyacrylonitrile, polyester, polyamide, polyurethane, polyethersulfone, polyetherketone, polyimide, polydimethylsiloxane, polycarbonate, and polyphenylsulfide. Or at least two of these copolymers. A 1st thermoplastic resin may be used independently and may use multiple.

  The first thermoplastic resin is preferably a resin having a high elastic modulus. Polyolefin is more preferable because it is inexpensive and can be easily molded under heating.

  It does not specifically limit as said polyolefin, A well-known polyolefin can be used. Specific examples of polyolefin include ethylene homopolymer polyethylene, ethylene-α-olefin copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, ethylene-acetic acid. Examples thereof include polyethylene resins such as vinyl copolymers. Polyolefins are polypropylene resins such as polypropylene as a propylene homopolymer and propylene-α-olefin copolymers, homopolymers or copolymers of conjugated dienes such as polybutene as a butene homopolymer, butadiene and isoprene. It may be. These polyolefins may be used alone or in combination. From the viewpoint of further increasing the heat resistance and elastic modulus, the polyolefin is preferably polypropylene.

Magnetic materials;
The magnetic material is not particularly limited, and is not particularly limited as long as the material has soft magnetism. A material having soft magnetism is a material that is strongly magnetized under the influence of a magnetic field but has no magnetic force in an environment without the influence of a magnetic field. As the magnetic material, for example, a metal alloy such as ferrite, sendust, and permalloy can be used. These magnetic materials may be used alone or in combination.

  Although content of a magnetic material is not specifically limited, Preferably it is 80 weight part or more with respect to 100 weight part of 1st thermoplastic resins, More preferably, it is 100 weight part or more. When content of a magnetic material is more than the said minimum, the electromagnetic wave absorptivity in a low frequency can be improved further. In addition, the upper limit of content of a magnetic material is not specifically limited, For example, it can be 300 weight part with respect to 100 weight part of thermoplastic resins.

  When a plurality of magnetic materials are used in combination, for example, ferrite as the first magnetic material and sendust as the second magnetic material may be used in combination. Moreover, you may use together the ferrite as a 1st magnetic material, and the permalloy as a 2nd magnetic material. Note that the first magnetic material and the second magnetic material are not limited to the above combinations, and other combinations may be used.

(Second layer)
A second thermoplastic resin;
It does not specifically limit as a 2nd thermoplastic resin, The thermoplastic resin demonstrated in the column of the above-mentioned 1st thermoplastic resin can be used. From the viewpoint of further increasing the productivity and further reducing the manufacturing cost, the second thermoplastic resin and the first thermoplastic resin are preferably the same thermoplastic resin. However, the second thermoplastic resin and the first thermoplastic resin may be different thermoplastic resins.

Conductive material;
The conductive material is not particularly limited, but is preferably graphite, carbon black, or carbon nanotube. When such a conductive material is used, even when the conductive material is highly filled, it is possible to obtain a resin molded body that is much lower in density and weight. Moreover, metal fibers, such as a stainless fiber, may be sufficient. These conductive materials may be used alone or in combination.

  Although content of an electroconductive material is not specifically limited, Preferably it is 80 weight part or more with respect to 100 weight part of thermoplastic resins, More preferably, it is 100 weight part or more. When content of an electroconductive material is more than the said minimum, the electromagnetic wave shielding property in a high frequency can be improved further. Moreover, the upper limit of content of an electroconductive material is although it does not specifically limit, For example, it can be 300 weight part.

  When a plurality of conductive materials are used in combination, a first conductive material having a particle size or fiber length of 5 μm or more and a second conductive material having a particle size or fiber length of 1 μm or less are used in combination. It is preferable to use materials having large particle diameters (fiber lengths) in combination. By using materials with different particle sizes (fiber lengths) in combination, the conductive material with a small particle size (short fiber length) efficiently fills the gap between the conductive materials with large particle size (long fiber length) Even better electromagnetic shielding properties can be expressed.

  Further, the content of the first conductive material with respect to 100 parts by weight of the second thermoplastic resin is preferably 65 parts by weight or more, more preferably 90 parts by weight or more, preferably 230 parts by weight or less, and 200 parts by weight or less. More preferred. The content of the second conductive material with respect to 100 parts by weight of the second thermoplastic resin is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably 70 parts by weight or less, and 60 parts by weight or less. More preferred. When content of each electroconductive material is more than the said lower limit, electromagnetic wave shielding can be improved further. When content of each electroconductive material is below the said upper limit, much more favorable moldability and intensity | strength can be maintained.

  As an example of using a plurality of conductive materials in combination, it is preferable to use a combination of graphite as the first conductive material and carbon black as the second conductive material. In this case, the graphite content is 90 to 200 parts by weight and the carbon black content is 10 to 60 parts by weight with respect to 100 parts by weight of the thermoplastic resin. preferable. Thus, the electromagnetic shielding performance can be further enhanced by using a combination of graphite as the first conductive material and carbon black as the second conductive material. However, the first conductive material and the second conductive material are not limited to the above combinations, and other combinations may be used. For example, graphite as the first conductive material and carbon nanotubes as the second conductive material may be used in combination. Further, graphite as the first conductive material and metal fibers such as stainless steel fibers as the second conductive material may be used in combination.

  The particle diameter or fiber length is, for example, a volume average particle diameter in the case of graphite. In the case of carbon black, it is the primary particle size. In the case of carbon nanotubes and metal fibers, it is the fiber length.

  The shape of the graphite is not particularly limited. From the viewpoint of further improving the electromagnetic wave shielding property, plate-like graphite is preferable. Moreover, it is preferable that the volume average particle diameter of graphite is 10 micrometers or more and 350 micrometers or less. When the volume average particle diameter of graphite is not less than the above lower limit, the electromagnetic wave shielding properties and the heat dissipation properties can be further enhanced. On the other hand, when the volume average particle diameter of the plate-like graphite is not more than the above upper limit, the impact resistance of the resin molded body can be further enhanced. Two or more types of graphite particles having different particle diameters may be used in combination.

  Further, in the present invention, the volume average particle diameter of graphite is a value calculated with a volume reference distribution by a laser diffraction method using a laser diffraction / scattering type particle size distribution measuring device in accordance with JIS Z 8825: 2013. Say.

  As carbon black, for example, oil furnace black such as ketjen black, acetylene black, channel black, thermal black and the like can be used. Among these, oil furnace black is preferable from the viewpoint of further improving the electromagnetic wave shielding performance of the resin molding. Carbon black may contain metal impurities such as Fe and Ni.

  The DBP oil absorption of the carbon black is preferably 100 ml / 100 g or more and 600 ml / 100 g or less. When the DBP oil absorption amount of carbon black is not less than the above lower limit, the electromagnetic wave shielding property of the resin molded product can be further enhanced. When the DBP oil absorption of carbon black is not more than the above upper limit, aggregation during kneading can be prevented and stability can be further improved.

  In the present invention, the DBP oil absorption of carbon black can be measured according to JIS K 6217-4. The DBP oil absorption amount can be measured using, for example, an absorption amount measuring instrument (manufactured by Asahi Research Institute, product number “S-500”).

  The primary particle size of carbon black is preferably 35 nm or more, more preferably 38 nm or more, preferably 50 nm or less, more preferably 45 nm or less. When the primary particle diameter of carbon black is within the above range, higher electromagnetic shielding performance can be obtained with a much lower carbon black content.

  In addition, the primary particle diameter of carbon black is an average primary particle diameter calculated | required using the image data of carbon black obtained with the transmission electron microscope, for example. As the transmission electron microscope, for example, a product name “JEM-2200FS” manufactured by JEOL Ltd. can be used.

  The fiber length of the carbon nanotube is preferably 0.1 μm or more, preferably 1.0 μm or less, more preferably 0.8 μm or less. The diameter of the carbon nanotube is preferably 8.0 nm or more, more preferably 10 nm or more, preferably 50 nm or less, more preferably 40 nm or less. When the fiber length and diameter of the carbon nanotube are within the above ranges, even higher electromagnetic shielding performance can be obtained.

  The fiber length and diameter of the carbon nanotube are, for example, average values obtained using image data of the carbon nanotube obtained by a transmission electron microscope. As the transmission electron microscope, for example, a product name “JEM-2200FS” manufactured by JEOL Ltd. can be used.

  Examples of the metal fiber include a metal fiber obtained by applying a metal film such as copper to a stainless fiber or an aramid fiber. Among these, stainless steel fibers are preferable from the viewpoint of further improving the electromagnetic shielding performance of the resin molded body.

  The fiber length of the metal fiber is preferably 2 mm or more, more preferably 4 mm or more, preferably 12 mm or less, more preferably 10 mm or less. The diameter of the metal fiber is preferably 5 μm or more, more preferably 7 μm or more, preferably 80 μm or less, more preferably 60 μm or less. When the fiber length and diameter of the metal fiber are within the above ranges, higher electromagnetic shielding performance can be obtained.

  The fiber length and diameter of the metal fiber are, for example, average values obtained using image data of the metal fiber obtained by a transmission electron microscope. As the transmission electron microscope, for example, a product name “JEM-2200FS” manufactured by JEOL Ltd. can be used.

(Other additives)
Various additives may be added to the first layer and the second layer, respectively, as optional components. Examples of additives include antioxidants such as phenols, phosphoruss, amines, and sulfurs; ultraviolet absorbers such as benzotriazoles and hydroxyphenyltriazines; and metal damage inhibitors. The additive may be a halogenated flame retardant such as hexabromobiphenyl ether or decabromodiphenyl ether; a flame retardant such as ammonium polyphosphate or trimethyl phosphate; various fillers; an antistatic agent; a stabilizer; Good. These may be used alone or in combination.

(Production method)
The resin molded body of the present invention can be produced, for example, by the following method.

  First, a first resin composition containing a first thermoplastic resin and a magnetic material powder and a second resin composition containing a second thermoplastic resin and a conductive material powder are prepared. The first resin composition and the second resin composition may further include various materials described above. In the first resin composition and the second resin composition, each material powder is preferably dispersed in the thermoplastic resin. In this case, the electromagnetic wave shielding property of the obtained resin molding can be further improved.

  The method for dispersing each material powder in the thermoplastic resin is not particularly limited, and examples thereof include a method in which the thermoplastic resin is heated and melted and kneaded with each material powder. By this method, it can be more uniformly dispersed.

  The kneading method is not particularly limited. For example, a twin screw kneader such as a plast mill, a kneader kneader, a single screw extruder, a twin screw extruder, a twin screw single screw extruder, a twin screw taper extruder, a feeder. Examples thereof include a method of kneading under heating using a kneading apparatus such as a ruder extruder, a plunger extruder, a Banbury mixer, and a roll. Among these, the method of melt kneading using an extruder is preferable.

  Next, a resin molded body can be obtained by a method of laminating the prepared first resin composition and second resin composition by, for example, multicolor injection molding, insert molding, sandwich molding, or the like.

  In molding the first resin composition and the second resin composition, it is preferable to integrally mold the target first layer and second layer by injection molding. In this case, the number of processing steps can be further reduced. Examples of the method for integrally molding the first layer and the second layer as the target by injection molding include the above-described multicolor injection molding, insert molding, and sandwich molding.

  Thus, in the resin molding of this invention, a physical property can be adjusted suitably according to the intended use.

  Hereinafter, the effects of the present invention will be clarified by giving specific examples and comparative examples of the present invention. In addition, this invention is not limited to a following example.

Example 1
100 parts by weight of polypropylene (PP) as the first thermoplastic resin and 150 parts by weight of ferrite powder as the magnetic material are melt kneaded at 200 ° C. using a lab plast mill (product number “R100” manufactured by Toyo Seiki Co., Ltd.). As a result, a first resin composition was obtained. In addition, 100 parts by weight of polypropylene (PP) as the second thermoplastic resin and 150 parts by weight of plate-like graphite powder as the conductive material are melt-kneaded at 200 ° C. using a lab plast mill. A resin composition was obtained. The first resin composition and the second resin composition thus obtained are two-color injection molded at a resin composition temperature of 230 ° C. and a mold temperature of 40 ° C., and then laminated. A resin molded body having two layers and having a length of 300 mm × width of 300 mm × thickness of 3 mm was obtained. The thickness of each resin layer (the first layer and the second layer) is 1.5 mm. The product name “BC10HRF” manufactured by Nippon Polypro Co., Ltd. was used as the polypropylene. The product name “EF-P” manufactured by Powdertech Co., Ltd. was used as the ferrite powder. As the plate-like graphite powder, trade name “F # 2” (average particle diameter 140 μm) manufactured by Nippon Graphite Co., Ltd. was used.

(Example 2)
The content of plate-like graphite as the first conductive material is 100 parts by weight, and further carbon black (product name “EC300J”, product name “EC300J”, primary particle diameter 40 nm, manufactured by Lion Corporation) as the second conductive material is 30 parts by weight. A resin molded body was obtained in the same manner as in Example 1 except that was used.

(Example 3)
A resin molded body was obtained in the same manner as in Example 2, except that Sendust powder (manufactured by Epson Atmix, trade name “SENDUST ALLOY TPF-18F”) was used as the magnetic material.

(Example 4)
A resin molded body was obtained in the same manner as in Example 2 except that permalloy powder (manufactured by Epson Atmix, trade name “50% FE-50% NI PF-20F”) was used as the magnetic material.

(Example 5)
Example except that 10 parts by weight of carbon nanotube (CNT, manufactured by Mitsubishi Corporation, trade name “Durobeads”, fiber length 0.8 μm, diameter 12 nm) was used instead of carbon black as the second conductive material. In the same manner as in Example 4, a resin molded body was obtained.

(Example 6)
Resin in the same manner as in Example 2 except that 10 parts by weight of stainless steel fiber (Nippon Seisen, Naslon SUS304, fiber length 8 mm, diameter 50 μm) was used instead of carbon black as the second conductive material. A molded body was obtained.

(Example 7)
Resin in the same manner as in Example 3 except that 10 parts by weight of stainless steel fiber (manufactured by Nippon Seisen Co., Ltd., NASLON SUS304, fiber length 8 mm, diameter 50 μm) was used instead of carbon black as the second conductive material. A molded body was obtained.

(Example 8)
Resin in the same manner as in Example 4 except that 10 parts by weight of stainless steel fiber (manufactured by Nippon Seisen Co., Ltd., NASLON SUS304, fiber length 8 mm, diameter 50 μm) was used instead of carbon black as the second conductive material. A molded body was obtained.

Example 9
The content of the ferrite powder as the first magnetic material is 60 parts by weight, and further 60 parts by weight of Sendust powder as the second magnetic material (trade name “SENDUST ALLOY TPF-18F” manufactured by Epson Atmix Co., Ltd.) A resin molded body was obtained in the same manner as in Example 1 except that it was used.

(Example 10)
The content of ferrite powder as the first magnetic material is 60 parts by weight, and permalloy powder as the second magnetic material (trade name “50% FE-50% NI PF-20F” manufactured by Epson Atmix Co., Ltd.) A resin molded body was obtained in the same manner as in Example 1 except that 60 parts by weight was used.

(Example 11)
The content of the ferrite powder as the first magnetic material is 60 parts by weight, and further 60 parts by weight of Sendust powder as the second magnetic material (trade name “SENDUST ALLOY TPF-18F” manufactured by Epson Atmix Co., Ltd.) A resin molded body was obtained in the same manner as in Example 2 except that it was used.

Example 12
A resin molded body was obtained in the same manner as in Example 11, except that acrylonitrile-butadiene-styrene copolymer (ABS, trade name “Stylac 181”) was used as the thermoplastic resin.

(Example 13)
A resin molded body was obtained in the same manner as in Example 11, except that polyamide (PA, trade name “Amilan CM1007” manufactured by Toray Industries, Inc.) was used as the thermoplastic resin.

(Comparative Example 1)
By melt-kneading 100 parts by weight of polypropylene (PP) as a thermoplastic resin and 150 parts by weight of ferrite powder as a magnetic material at 200 ° C. using a lab plast mill (product number “R100” manufactured by Toyo Seiki Co., Ltd.) A resin composition was obtained. The obtained resin composition was injection-molded at a resin composition temperature of 230 ° C. and a mold temperature of 40 ° C. to obtain a resin molded body having a length of 300 mm × width of 300 mm × thickness of 3 mm. The product name “BC10HRF” manufactured by Nippon Polypro Co., Ltd. was used as the polypropylene. The product name “EF-P” manufactured by Powdertech Co., Ltd. was used as the ferrite powder.

(Comparative Example 2)
A resin molded body was obtained in the same manner as in Comparative Example 1 except that 150 parts by weight of plate-like graphite powder (trade name “F # 2” manufactured by Nippon Graphite Co., Ltd.) was used as the conductive material instead of the magnetic material. It was.

(Comparative Example 3)
100 parts by weight of polypropylene (PP) as a thermoplastic resin, 60 parts by weight of ferrite powder as a magnetic material, and 60 parts by weight of plate-like graphite powder as a conductive material, Laboplast mill (product number “R100” manufactured by Toyo Seiki Co., Ltd.) ) Was melt kneaded at 200 ° C. to obtain a resin composition. The obtained resin composition was injection-molded at a resin composition temperature of 230 ° C. and a mold temperature of 40 ° C. to obtain a resin molded body having a length of 300 mm × width of 300 mm × thickness of 3 mm. The product name “BC10HRF” manufactured by Nippon Polypro Co., Ltd. was used as the polypropylene. The product name “EF-P” manufactured by Powdertech Co., Ltd. was used as the ferrite powder. As the plate-like graphite powder, trade name “F # 2” (average particle diameter 140 μm) manufactured by Nippon Graphite Co., Ltd. was used.

(Comparative Example 4)
100 parts by weight of polypropylene (PP) as a thermoplastic resin and 60 parts by weight of plate-like graphite powder as a conductive material were used at 200 ° C. using a lab plast mill (product number “R100” manufactured by Toyo Seiki Co., Ltd.). A resin composition was obtained by melt-kneading. As a metal material, permalloy powder was pressed and hardened by a press machine, and then fired at 1000 ° C. to obtain a permalloy flat molded body having a thickness of 1.5 mm. Permalloy flat plate molded body is inserted into a mold, and the obtained resin composition is injection-molded at a resin composition temperature of 230 ° C. and a mold temperature of 40 ° C., so that the length is 300 mm × width 300 mm × thickness 3 mm. A metal resin integrated molded body was obtained. The product name “BC10HRF” manufactured by Nippon Polypro Co., Ltd. was used as the polypropylene. As the plate-like graphite powder, trade name “F # 2” (average particle diameter 140 μm) manufactured by Nippon Graphite Co., Ltd. was used. As the permalloy powder, a product name “Fe-50% Ni PF-20F” manufactured by Epson Atmix Co., Ltd. was used.

(Evaluation)
The following evaluation was performed about the resin molding obtained in the Example and the comparative example. The results are shown in Tables 1 and 2 below.

<Magnetic field shielding performance at a frequency of 10 MHz>
The magnetic shielding performance (unit: dB) of the resin molded body at a frequency of 10 MHz was measured by the KEC method (KEC: abbreviation of “KEC Kansai Electronics Promotion Center”) using an electromagnetic shielding effect measuring tool MA8602B (manufactured by Anritsu). did. As a measuring instrument, product number “Spectrum Analyzer N9000A” manufactured by Agilent Technologies, Inc. was used.

<Electric field shielding performance at 1 GHz frequency>
The electric field shielding performance (unit: dB) of the resin molded body at a frequency of 1 GHz was measured using a shield-characteristic measuring jig 2-focus flat cavity (DFFC) (manufactured by Sanken). As a measuring instrument, a product number “Component Analyzer N4375D” manufactured by Agilent Technologies, Inc. was used.

<Real part μ ′ of complex relative permeability at frequency 10 MHz>
The real part μ ′ of the complex relative permeability at a frequency of 10 MHz of the first layer of the example, the resin layer containing the magnetic material of the comparative example, and the metal layer of the comparative example is a material impedance analyzer (manufactured by Agilent Technologies, product number “E4991A”). )).

<Surface resistivity>
The surface resistivity of the resin layer containing the conductive material of the second layer of the example and the comparative example was measured at room temperature and atmospheric pressure using a low resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., product number “Loresta-GP MCP-T610”). Measured in.

<Density>
The density of the resin molding was measured using a high-precision electronic hydrometer (manufactured by ALFAMIRAGE, trade name “MDS-300”) by an underwater substitution method.

<Transmission attenuation factor at a frequency of 10 MHz>
The transmission attenuation factor (unit: dB) at a frequency of 10 MHz of the resin molded body was measured by a microstrip line method in accordance with IEC62333-2. The transmission attenuation factor was measured by bringing the first layer of the resin molded body into close contact with the transmission path. As a measuring instrument, a product number “Network Analyzer N5222A” manufactured by Agilent Technologies was used.

DESCRIPTION OF SYMBOLS 1 ... Resin molding 2 ... 1st layer 2a ... Main surface 3 ... 2nd layer

Claims (11)

A resin molded body comprising a first layer and a second layer laminated on the first layer, wherein the first layer comprises a first thermoplastic resin and a magnetic material. Including
The second layer includes a second thermoplastic resin and a conductive material different from the magnetic material;
The magnetic shielding performance at a frequency of 1 MHz to 100 MHz of the resin molding is 6 dB or more,
A resin molded body having an electric field shielding performance of 20 dB or more at a frequency of 0.1 GHz to 10 GHz of the resin molded body.   2. The resin molded body according to claim 1, wherein the real part μ ′ of the complex relative permeability at a frequency of 10 MHz of the first layer is 3 or more.   The resin molded body according to claim 1 or 2, wherein a content of the magnetic material with respect to 100 parts by weight of the first thermoplastic resin is 80 parts by weight or more. The resin molded product according to any one of claims 1 to 3, wherein the surface resistivity of the second layer is less than 10 ² Ω / sq.   The resin molding according to any one of claims 1 to 4, wherein the conductive material is at least one carbon material selected from the group consisting of graphite, carbon black, and carbon nanotubes.   The said electroconductive material contains the 1st electroconductive material whose particle size or fiber length is 5 micrometers or more, and the 2nd electroconductive material whose particle diameter or fiber length is 1 micrometer or less of Claims 1-5 The resin molding of any one of Claims. The content of the first conductive material with respect to 100 parts by weight of the second thermoplastic resin is 65 parts by weight or more and 230 parts by weight or less,
The resin molded product according to claim 6, wherein the content of the second conductive material with respect to 100 parts by weight of the second thermoplastic resin is 5 parts by weight or more and 70 parts by weight or less.   The resin molded body according to any one of claims 1 to 7, wherein a content of the conductive material with respect to 100 parts by weight of the second thermoplastic resin is 80 parts by weight or more. The resin molded body according to any one of claims 1 to 8, wherein the density of the resin molded body is 4.0 g / cm ³ or less. The resin molded body is an injection molded body,
The resin molded body according to any one of claims 1 to 9, wherein the first layer and the second layer are integrally molded.   The transmission attenuation factor when the first layer in the resin molded body is measured in close contact with a transmission line by a microstrip line method is 5 dB or more at a frequency of 10 MHz. The resin molding as described in 2.

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