JP6804846B2 - Resin molded body - Google Patents

Description

The present invention relates to a resin molded product having thermal conductivity.

Conventionally, a metal plate, a resin molded body having thermal conductivity, or the like has been used for a housing of a communication device used indoors or outdoors or an electronic device such as a security camera or a smart meter.

Patent Document 1 below discloses a resin molded product made of a thermoplastic resin composition containing pitch-based carbon fibers. In Patent Document 1, the pitch-based carbon fibers are oriented in the MD direction (resin flow direction at the time of injection molding) in the resin molded body. Further, it is described that the ratio (λ2 / λ1) of the thermal conductivity λ1 in the thickness direction to the thermal conductivity λ2 in the MD direction is 10 or more.

Further, Patent Document 2 below discloses a heat radiating chassis which is a resin molded body made of a heat conductive resin composition. Patent Document 2 describes that the heat conductive resin composition contains one or more heat conductive fillers of graphite, magnesium oxide and boron nitride. Further, it is described that the blending amount of the heat conductive filler is 10 to 1000 parts by mass with respect to 100 parts by mass of the resin.

JP-A-2015-120358 Japanese Unexamined Patent Publication No. 2008-31359

In recent years, a communication antenna may be arranged inside a housing of a communication device indoors or outdoors or an electronic device such as a security camera or a smart meter. Therefore, electromagnetic wave transmission may be required for the housings of communication devices and electronic devices.

However, the resin molded products of Patent Document 1 and Patent Document 2 did not have sufficient electromagnetic wave transmission. In Patent Document 2, it is described that the electromagnetic wave shielding property is rather excellent, and the electromagnetic wave transmission property is not described. Further, in the resin molded products of Patent Document 1 and Patent Document 2, the thermal diffusivity in the plane direction was not sufficient.

An object of the present invention is to provide a resin molded product having excellent thermal diffusivity and electromagnetic wave transmission.

The resin molded body according to the present invention is a resin molded body having thermal conductivity and having a main surface, and on the main surface, an arbitrary direction is the x direction and a direction orthogonal to the x direction is the y direction. When the thickness direction of the resin molded body is the z direction, the thermal conductivity λx in the x direction, the thermal conductivity λy in the y direction, and the thermal conductivity λz in the z direction are min (λx, λy). ) / Λz ≧ 3, and the electromagnetic wave shielding performance at a frequency of 1 GHz measured in accordance with the KEC method is 10 dB or less.

In a specific aspect of the resin molded product according to the present invention, the main surface is a flat surface or a curved surface.

In another specific aspect of the resin molded product according to the present invention, λx / λy satisfies 0.5 or more and 2 or less in the λx and the λy.

In another specific aspect of the resin molded product according to the present invention, the λx and the λy satisfy max (λx, λy) ≧ 1 W / (m · K).

Yet another specific aspect of the resin molded article according to the present invention is a molded article of a resin composition containing a resin and a conductive heat conductive filler.

In still another specific aspect of the resin molded product according to the present invention, the aspect ratio of the conductive heat conductive filler is 3 or more.

In still another specific aspect of the resin molded product according to the present invention, the content of the conductive heat conductive filler is 0.1 part by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the resin.

In yet another specific aspect of the resin molded article according to the present invention, the conductive heat conductive filler is made of a carbon material.

In yet another particular aspect of the resin molded article according to the present invention, the resin composition further comprises an insulating heat conductive filler.

In still another specific aspect of the resin molded product according to the present invention, the content of the insulating heat conductive filler is 100 parts by weight or less with respect to 100 parts by weight of the resin.

In yet another specific aspect of the resin molded body according to the present invention, the insulating thermal conductive filler is composed of at least one selected from the group consisting of aluminum oxide, magnesium oxide, boron nitride and aluminum nitride. ing.

In yet another specific aspect of the resin molded product according to the present invention, the resin contains a first resin made of an olefin resin.

In yet another specific aspect of the resin molded article according to the present invention, the temperature at which the resin indicates the maximum value of loss tangent measured by dynamic viscoelasticity measurement at a frequency of 1 Hz and a strain of 0.3% is −10 ° C. It contains the following second resin.

In still another specific aspect of the resin molded product according to the present invention, the content of the second resin is 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the resin.

According to the present invention, it is possible to provide a resin molded product having excellent thermal diffusivity and electromagnetic wave transmission.

(A) is a schematic plan view of the resin molded product obtained in the examples, and (b) is a schematic cross-sectional view taken along the line AA. It is a schematic block diagram of the housing obtained in an Example.

The details of the present invention will be described below.

The resin molded article of the present invention is a thermally conductive resin molded article having thermal conductivity. The resin molded product of the present invention has a main surface. In the resin molded body of the present invention, the thermal conductivity λx in the x direction, the thermal conductivity λy in the y direction, and the thermal conductivity λz in the z direction satisfy min (λx, λy) / λz ≧ 3. Further, the resin molded product of the present invention has an electromagnetic wave shielding performance of 10 dB or less.

The x direction is an arbitrary direction along the main surface. The y direction is a direction along the main surface and orthogonal to the x direction. The z direction is the thickness direction of the resin molded product. The thickness direction of the resin molded product is a direction orthogonal to the main surface. Therefore, the z direction is a direction orthogonal to the x direction and the y direction. The main surface may be a flat surface or a curved surface. Further, in the present specification, the main surface means the surface having the largest area on the outer surface of the resin molded product.

The thermal conductivity in each of the x-direction, y-direction, and z-direction can be calculated by using the following formula (1).

Thermal conductivity (W / (m · K)) = thermal diffusivity x specific gravity x specific heat ... (1)

In the formula (1), the thermal diffusivity in each of the x-direction, y-direction, and z-direction can be measured by using, for example, Bethel Co., Ltd., product number name: TA33.

The above-mentioned min (λx, λy) means the value of λx and λy, whichever has the lower thermal conductivity. Therefore, min (λx, λy) / λz ≧ 3 means that the ratio of the lower thermal conductivity of λx and λy to λz is 3 or more.

The electromagnetic wave shielding performance is an electromagnetic wave shielding performance at a frequency of 1 GHz. The electromagnetic wave shielding performance can be measured according to the KEC method. The KEC method is a method for measuring electromagnetic wave shielding performance developed by the KEC Kansai Electronics Industry Promotion Center. In the KEC method, the electromagnetic wave shielding performance can be measured using, for example, an electric field shield measuring device (manufactured by Microwave Factory Co., Ltd., trade name "KEC method shield effect measuring device").

Since the resin molded body of the present invention has min (λx, λy) / λz ≧ 3, the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction. Therefore, the resin molded product of the present invention is excellent in thermal conductivity in the plane direction. Further, since the resin molded product of the present invention has an electromagnetic wave shielding performance of 10 dB or less at a frequency of 1 GHz, it is excellent in electromagnetic wave transmission.

Since the resin molded product of the present invention has excellent thermal diffusivity, it can be suitably used for indoor and outdoor communication devices and housings for electronic devices such as security cameras and smart meters. In particular, since it has excellent thermal diffusivity in the plane direction, it is possible to prevent heat such as sunlight from penetrating into the inside of communication equipment and electronic equipment. Specifically, for example, the heat of the portion exposed to direct sunlight can be diffused to the shadowed surface. Further, by diffusing the heat of the heat-generating component inside the housing in the plane direction, it is possible to prevent the temperature of the communication device or the electronic device from partially rising. Further, if a part of the housing has the shape of the heat radiating fin, it is possible to exert the heat radiating effect. For example, when the temperature of a CPU or the like becomes high, its operating ability is reduced, so that heat in the vicinity of the CPU can be diffused over a wide range.

In the present invention, from the viewpoint of further enhancing the thermal conductivity in the plane direction, min (λx, λy) / λz ≧ 5, and more preferably min (λx, λy) / λz ≧ 10. The upper limit of min (λx, λy) is preferably as high as possible, but it is preferably about 20 due to the nature of the material. Specifically, the aspect ratio of the filler contributes, but when the thickness of the filler becomes thin, the filler itself may be curled up in the composite resin and sufficient heat conduction characteristics may not be obtained.

In the present invention, it is preferable that λx / λy is 0.5 or more and 2 or less in λx and λy. In this case, heat can be diffused even more uniformly in the plane direction. In particular, since the portion exposed to direct sunlight (high temperature portion) and the shaded portion (low temperature portion) are not always on the same surface, a form in which heat is diffused in any horizontal direction is preferable. Therefore, more preferably λx / λy is 0.7 or more, further preferably λx / λy is 0.9 or more, more preferably λx / λy is 1.6 or less, and further preferably λx / λy is 1.2 or less. is there.

It is preferable that the λx and the λy satisfy max (λx, λy) ≧ 1 W / (m · K). The above max (λx, λy) means the value of λx and λy, whichever has the higher thermal conductivity. Therefore, max (λx, λy) ≧ 1 W / (m · K) means that the thermal conductivity of λx and λy, whichever has the higher thermal conductivity, is 1 W / (m · K) or more. There is. When max (λx, λy) is in the above range, the thermal diffusivity can be further enhanced. From the viewpoint of further enhancing the thermal diffusivity, the above λx and the above λy are more preferably max (λx, λy) ≧ 3W / (m · K), and further preferably max (λx, λy) ≧ 10W / (. m ・ K). The upper limit of max (λx, λy) is preferably as high as possible, but it is preferably about 20 due to the nature of the material. In the present invention, both λx and λy are preferably 1 W / (m · K) or more, more preferably 3 W / (m · K) or more, and further preferably 10 W / (m · K) or more.

Further, from the viewpoint of further enhancing the electromagnetic wave transmission, the electromagnetic wave shielding performance is preferably 5 dB or less, and more preferably the electromagnetic wave shielding performance is 3 dB or less.

The resin molded product of the present invention is preferably a molded product of a resin composition containing a resin and a heat conductive filler. The resin molded product of the present invention can be obtained by molding the resin composition by, for example, a method such as press working, extrusion processing, extrusion laminating processing, or injection molding.

The details of the resin composition will be described below.

(resin)
The resin is not particularly limited, and various known synthetic resins can be used. Preferably, the synthetic resin is a thermoplastic resin. When a thermoplastic resin is used, the moldability of the resin composition can be further improved.

The thermoplastic resin is not particularly limited, and a known thermoplastic resin can be used. Specific examples of the thermoplastic resin include polyolefin, polystyrene, polyacrylate, polymethacrylate, polyacrylonitrile, polyester, polyamide, polyurethane, polyethersulfone, polyetherketone, polyimide, polydimethylsiloxane, polycarbonate, or at least two of them. Species copolymers and the like. The thermoplastic resin may be used alone or in combination of two or more.

The thermoplastic resin is preferably a resin having a high elastic modulus. Polyolefins are more preferred because they are inexpensive and easy to mold under heating.

The polyolefin is not particularly limited, and known polyolefins can be used. Specific examples of the polyolefin include polyethylene which is an ethylene homopolymer, an ethylene-α-olefin copolymer, an ethylene- (meth) acrylic acid copolymer, an ethylene- (meth) acrylic acid ester copolymer, and an ethylene-acetic acid. Polyethylene resin such as vinyl copolymer, polypropylene resin which is propylene homopolymer, polypropylene resin such as propylene-α-olefin copolymer, polybutene which is butene homopolymer, butadiene, isoprene, etc. At least one selected from the group consisting of coalescing or copolymers can be used. From the viewpoint of further increasing heat resistance and elastic modulus, polypropylene is preferable as the polyolefin.

Further, the thermoplastic resin has a temperature of −10 ° C., which is the maximum value of the loss tangent measured by the dynamic viscoelasticity measurement at a frequency of 1 Hz and a strain of 0.3% with the first resin made of an olefin resin. It is preferable to contain the following second resin. In this case, the impact resistance of the resin molded product can be further improved.

The loss tangent can be determined by measuring in accordance with JIS K 7244-4. Specifically, a test sheet having a width of 5 mm, a length of 24 mm, and a thickness of 0.3 mm is prepared. The prepared test sheet is obtained by measuring the temperature dispersion of dynamic viscoelasticity under the conditions of a strain amount of 0.3%, a frequency of 1 Hz and a heating rate of 3 ° C./min. The temperature dispersion measurement of dynamic viscoelasticity can be performed using, for example, a dynamic viscoelasticity measuring device (manufactured by Leometrics, trade name "RSA").

As the first resin, the above-mentioned polyolefin can be used. The second resin is not particularly limited, but is preferably a copolymer having an aromatic vinyl block, which is a polymer of an aromatic vinyl monomer. More preferably, it is a block copolymer having the above aromatic vinyl block and a diene block which is a polymer of a conjugated diene monomer.

The aromatic vinyl monomer is not particularly limited, and is, for example, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene. , 4-tert-butyl styrene, tert-butoxy styrene and the like.

The conjugated diene monomer is not particularly limited, and examples thereof include conjugated diene having 4 to 12 carbon atoms such as butadiene, isoprene, piperylene, and dimethylbutadiene.

Examples of the copolymer having such an aromatic vinyl block include a styrene-based elastomer.

Specific examples of the styrene-based elastomer include styrene-butadiene copolymer (SB), styrene-butadiene-styrene copolymer (SBS), styrene-isoprene copolymer (SI), and styrene-isoprene-styrene copolymer. (SIS), Styrene-Ethylene-Butylene Copolymer (SEB), Styrene-Ethene-Butylene-Styrene Copolymer (SEBS), Styrene-Ethethylene-propylene Copolymer (SEP), and Styrene-Ethene-propylene-Styrene Examples thereof include copolymers such as styrene. These copolymers may be block copolymers. Further, it may be a linear type or a radial type. These copolymers may be used alone or in combination of two or more. From the viewpoint of further enhancing the impact resistance of the resin molded product, the styrene-based elastomer is preferably a styrene-ethylene-butylene-styrene block copolymer (SEBS). In the present invention, as long as the loss tangent satisfies the above range, another polymer such as polyolefin may be used as the second resin.

The content of the first resin is preferably 60 parts by weight or more, more preferably 80 parts by weight or more, preferably 95 parts by weight or less, more preferably 90 parts by weight or more, based on 100 parts by weight of the resin. It is less than the weight part. When the content of the first resin is within the above range, the elastic modulus and heat resistance of the resin molded product can be further increased.

The content of the second resin is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably 50 parts by weight or less, more preferably 40 parts by weight or more, based on 100 parts by weight of the resin. It is less than a part by weight, more preferably 20 parts by weight or less. When the content of the second resin is within the above range, the impact resistance of the resin molded product can be further enhanced.

(Thermal conductivity filler)
As the heat conductive filler, conductive and insulating heat conductive fillers can be used. However, as the heat conductive filler, it is preferable to use a conductive filler which is relatively inexpensive and has high thermal conductivity, more preferably a carbon material, and further preferably a carbon material having a graphene laminated structure. When a carbon material having a graphene laminated structure is used, the thermal conductivity of the resin molded product can be further enhanced.

The carbon material is not particularly limited, but graphite, flaky graphite, graphene and the like can be used. From the viewpoint of further enhancing the thermal diffusivity, graphite or flaky graphite is preferable, and graphite is more preferable. These may be used alone or in combination of two or more. The flaky graphite is obtained by exfoliating the original graphite, and refers to a graphene sheet laminate thinner than the original graphite. The number of graphene sheets laminated in the flaky graphite may be smaller than that of the original graphite.

In the carbon material having the graphene laminated structure, the number of laminated graphene sheets is preferably 3000 layers or less, more preferably 2000 layers or less, and further preferably 1500 layers or less. The number of laminated graphene sheets is preferably 100 layers or more, more preferably 500 layers or more, and further preferably 800 layers or more.

The number of laminated graphene sheets in graphite can be determined by measuring the thickness of graphite using a scanning electron microscope (SEM) and dividing by the thickness of the graphene sheet of 0.33 nm / layer.

The number of laminated graphene sheets of flake graphite can be measured using a transmission electron microscope (TEM), and refers to the arithmetic mean of the number of layers of each flake graphite. When the number of layers is at least the above lower limit, the cost of the carbon material having a graphene structure can be suppressed. On the other hand, from the viewpoint of the rigidity reinforcing effect as a filler, the upper limit of the number of laminated graphene sheets is about 3500 layers.

The aspect ratio of the conductive heat conductive filler is preferably 3 or more, and more preferably 5 or more. When the aspect ratio of the conductive heat conductive filler is at least the above lower limit, the heat diffusivity in the plane direction can be further enhanced. If the aspect ratio is too large, the effect may be saturated and no further effect may be expected. Therefore, it is desirable that the upper limit of the aspect ratio of the conductive heat conductive filler is 20. Further, in the present specification, the aspect ratio means the ratio of the maximum dimension of the filler in the stacking surface direction to the thickness of the filler.

The content of the conductive heat conductive filler is preferably 0.1 part by weight or more, more preferably 1 part by weight or more, still more preferably 10 parts by weight or more, preferably 50 parts by weight or less, based on 100 parts by weight of the resin. More preferably, it is 20 parts by weight or less. When the content of the conductive heat conductive filler is at least the above lower limit, the heat diffusivity in the surface direction of the resin molded product can be further enhanced. Further, when the content of the conductive heat conductive filler is not more than the above upper limit, the electromagnetic wave transmission and the impact resistance can be further improved.

The heat conductive filler may be an insulating heat conductive filler. However, it is preferable to use both a conductive heat conductive filler and an insulating heat conductive filler as the heat conductive filler. In this case, both thermal diffusivity and electromagnetic wave transmission can be achieved at a higher level.

The insulating heat conductive filler is not particularly limited, and examples thereof include aluminum oxide, magnesium oxide, boron nitride, and aluminum nitride. These may be used alone or in combination of two or more. From the viewpoint of achieving both thermal diffusivity and electromagnetic wave transmission at a higher level, it is preferable to use aluminum oxide or boron nitride as the insulating thermal conductive filler.

The content of the insulating heat conductive filler is not particularly limited, but is preferably 10 parts by weight or more, more preferably 30 parts by weight or more, and further preferably 50 parts by weight or more with respect to 100 parts by weight of the resin. When the content of the insulating heat conductive filler is at least the above lower limit, the electromagnetic wave transmission of the resin molded product can be further enhanced. On the other hand, the content of the insulating heat conductive filler is preferably 100 parts by weight or less, more preferably 70 parts by weight or less. When the content of the insulating heat conductive filler is not more than the above upper limit, the impact resistance of the resin molded product can be further enhanced.

The heat conductive filler is preferably dispersed in the resin. When the heat conductive filler is dispersed in the resin, the heat diffusibility in the surface direction of the resin molded product can be further enhanced. More preferably, it is desirable that the insulating heat conductive filler is dispersed so as to surround the periphery of the conductive heat conductive filler. Further, it is preferable that the conductive heat conductive filler and the insulating heat conductive filler are dispersed so as to have contact points. This is because if the conductive heat conductive fillers are present in a row, the electromagnetic wave transmission may be lowered. Further, the thermal diffusivity can be further improved by connecting the conductive heat conductive filler and the insulating heat conductive filler with contact points.

The method for dispersing the heat conductive filler in the synthetic resin is not particularly limited, but the heat conductive filler can be dispersed by kneading the synthetic resin and the heat conductive filler.

The kneading method is not particularly limited, but for example, a method of kneading under heating using a kneading device such as a twin-screw kneader such as a plast mill, a single-screw extruder, a twin-screw extruder, a Banbury mixer, or a roll. And so on. Among these, a method of melt-kneading using an extruder is preferable.

(Other additives)
Various additives may be added as optional components to the resin composition. Examples of the additive include antioxidants such as phenol-based, phosphorus-based, amine-based, and sulfur-based; UV absorbers such as benzotriazole-based and hydroxyphenyltriazine-based; metal damage retardants; hexabromobiphenyl ether and decabromo. Halogenated flame retardants such as diphenyl ether; flame retardants such as ammonium polyphosphate and trimethyl phosphate; various fillers; antistatic agents; stabilizers; pigments and the like. These may be used alone or in combination of two or more.

In the present invention, by changing the types of the resin and the heat conductive filler in the resin composition constituting the resin molded product, the blending ratio of each component, and the like, heat diffusivity in each direction, electromagnetic wave transmission, and the like can be obtained. Various physical properties can be adjusted as appropriate.

As described above, in the resin molded product of the present invention, the physical properties can be appropriately adjusted 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. The present invention is not limited to the following examples.

( Reference example 1)
95 parts by weight of polypropylene (PP, manufactured by Prime Polymer Co., Ltd., trade name "E-150GK"), 5 parts by weight of styrene-ethylene-butadiene-styrene copolymer (SEBS, manufactured by Asahi Kasei Co., Ltd., trade name "H1062"), Laplastomill (manufactured by Toyo Seiki Co., Ltd., product number "R100") with 5 parts by weight of polypropylene (manufactured by Ito Graphite Co., Ltd., trade name "CNP7", number of laminated graphenes: 1300 layers, average particle size: 7 μm, thickness: 420 nm) Was melt-kneaded at 200 ° C. to obtain a resin composition. The obtained resin composition was adjusted to have a length of 6 mm, a width of 6 mm, and a height of 5 mm, placed on a press plate, and heated until the temperature reached 200 ° C. After that, it was formed into a sheet by press working under the conditions of a pressure of 20 MPa and a time of 5 minutes. Subsequently, a resin sheet having a length of 300 mm, a width of 300 mm, and a thickness of 2 mm was obtained by pressing at room temperature.

Next, the obtained resin sheet was heated and melted in a far-infrared oven until the temperature of the front and back surfaces reached 200 ° C., and then pressed at room temperature in a mold to obtain a box-shaped resin molded product. .. A schematic plan view of the resin molded product 1 obtained in FIG. 1A is shown, and FIG. 1B shows a schematic cross-sectional view taken along the line AA. Next, another resin molded body 1 is prepared by the same method, and as shown in FIG. 2, the periphery of the pair of resin molded bodies 1 is sandwiched between clips 2 to form a completely closed box-shaped housing 3. Obtained.

(Example 2)
A housing was obtained in the same manner as in Reference Example 1 except that the amount of graphite added was 10 parts by weight and 50 parts by weight of aluminum oxide (manufactured by Nippon Light Metal Co., Ltd., trade name “LS-210B”) was further added.

(Example 3)
Example 2 and Example 2 except that the amount of graphite added was 20 parts by weight and 50 parts by weight of magnesium oxide (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "Pyrokisma (registered trademark) 5301K") was added instead of aluminum oxide. A housing was obtained in the same manner.

( Reference example 4)
100 parts by weight of polyethylene (PE, manufactured by Japan Polyethylene Corporation, trade name "Novatec (registered trademark) LJ803") and graphite (manufactured by Ito Graphite, trade name "CNP7", number of graphene layers: 1300 layers, average particle size: A resin composition was obtained by melt-kneading 5 parts by weight (7 μm, thickness: 420 nm) at 140 ° C. using a laboplast mill (manufactured by Toyo Seiki Co., Ltd., product number “R100”). The obtained resin composition was adjusted to have a length of 6 mm, a width of 6 mm, and a height of 5 mm, placed on a press plate, and heated until the temperature reached 140 ° C. After that, it was formed into a sheet by press working under the conditions of a pressure of 20 MPa and a time of 5 minutes. Next, by pressing at room temperature, a resin sheet having a length of 300 mm, a width of 300 mm, and a thickness of 2 mm was obtained.

The obtained resin sheet was adjusted into a sheet pellet of 2 mm × 5 mm × 5 mm, and the sheet pellet-shaped resin sheet was put into a 160-ton injection molding machine (manufactured by Toshiba Machine Co., Ltd., product number “EC160NP”). Subsequently, it is injected into a mold under the condition that the resin temperature becomes 180 ° C., cooled to 50 ° C., and taken out after 1 minute has passed to obtain a box-shaped resin molded product having the same shape as Reference Example 1. Obtained. The obtained resin molded product was sandwiched between clips in the same manner as in Reference Example 1 to obtain a box-shaped housing having a completely closed space.

(Example 5)
The housing is the same as in Reference Example 4 except that the amount of graphite added is 10 parts by weight and 50 parts by weight of magnesium oxide (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "Pyrokisma (registered trademark) 5301K") is further added. Was produced.

(Example 6)
A housing was obtained in the same manner as in Example 5 except that the amount of magnesium oxide added was 20 parts by weight and 20 parts by weight of aluminum oxide (manufactured by Nippon Light Metal Co., Ltd., trade name “LS-210B”) was further added. ..

(Comparative Example 1)
A housing was obtained in the same manner as in Reference Example 1 except that graphite was not used.

(Comparative Example 2)
A housing was obtained in the same manner as in Example 6 except that the amount of graphite added was 5 parts by weight, the amount of aluminum oxide added was 120 parts by weight, and magnesium oxide was not used.

Details of the compositions of Reference Example 1 , Examples 2 to 3, Reference Example 4, Examples 5 to 6 and Comparative Examples 1 and 2 are shown in Table 1 below.

(Evaluation)
The following evaluations were performed on the resin molded bodies and housings obtained in Reference Example 1 , Examples 2 to 3, Reference Example 4, Examples 5 to 6, and Comparative Examples 1 and 2. The results are shown in Table 2 below.

<Evaluation method>
Measurement of thermal conductivity;
A test piece was cut out from the bottom surface of the housing to a size of 100 mm × 100 mm and used for measuring the thermal conductivity.

When the arbitrary direction on the plane or curved surface of the test piece constituting the housing is the x direction and the direction orthogonal to the x direction is the y direction, and the thickness direction of the test piece is the z direction, the thermal conductivity in the x direction is λx. , The thermal conductivity λy in the y direction and the thermal conductivity λz in the z direction were measured using the following equations, respectively.

Thermal conductivity (W / (m · K)) = thermal diffusivity x specific gravity x specific heat ... (1)

In the formula (1), the measurement of the thermal diffusivity in each direction was performed using the product number "TA33" manufactured by Bethel. Using λx, λy and λz obtained as described above, min (λx, λy) / λz, λx / λy and max (λx, λy) were obtained.

In addition, when evaluation is performed by this measurement method, the radiant heat of the xenon flash to be irradiated may not be detected in the in-plane direction. Therefore, if necessary, the test piece cut out from the housing is melt-heated and cooled. The thickness was reduced by pressing to adjust the sample thickness to a detectable level.

The specific gravity was measured using the trade name "MDS-300" manufactured by ALFAMIRAGE.

The specific heat was measured using the trade name "DSC-6200" manufactured by Seiko Instruments.

Electromagnetic wave shielding performance;
A test piece was cut out from the bottom surface of the housing to a size of 150 mm × 150 mm and used for measuring the electromagnetic wave shielding performance. For the electromagnetic wave shielding performance, the electromagnetic wave shielding performance at a frequency of 1 GHz was measured in accordance with the KEC method developed by the KEC Kansai Electronics Industry Promotion Center, and the loss of the electric field was observed. In the KEC method, the electromagnetic wave shielding performance was measured using, for example, an electric field shield measuring device (manufactured by Microwave Factory, trade name "KEC method shield effect measuring device").

Specifically, a test piece is placed at an intermediate position between the electromagnetic wave generated by the signal generator and the case provided with the receiving device that receives the electromagnetic wave, and the shield performance is evaluated by observing the difference from the case without the test piece. It is a device. The device can measure from 100 MHz to 1 GHz, but in the present invention, the shield performance at 1 GHz is used as the evaluation value. Further, although this device can evaluate the shielding performance of the electric field and the magnetic field, the present invention uses the attenuation amount of the electric field as the evaluation value because it is composed of the material in which the shielding property of the electric field is dominant. And said.

Evaluation of thermal diffusivity;
A test piece was cut out from the bottom surface of the housing to a size of 100 mm × 100 mm and used for measurement of thermal diffusivity evaluation.

For thermal diffusivity evaluation, a heater (manufactured by Sakaguchi Electric Heat Co., Ltd., product number "Microceramic Heater MS-5") is placed in the lower center of the test piece, and heat conductive grease (manufactured by AINEX) is placed between the test piece and the heater. , Part number "GS-04", thermal conductivity 3.8 W / (m · K)) 1 g was uniformly applied to bond. Further, a thermocouple was fixed with a tape on the upper side of the test piece directly above the heater, and the temperature was measured using the thermocouple. The thickness of the test piece was 1.6 mm.

The heater is heated at a voltage of 8 V using a DC power supply device, and after 800 seconds (the time when the temperature rise becomes small and the saturation temperature is reached), the temperature of the upper center portion of the test piece is measured. The lower the temperature, the lower the heat permeability, that is, the heat is diffused to the surroundings, so that it can be said that the housing has good heat diffusivity.

The results are shown in Table 2 below.

1 ... Resin molded body 2 ... Clip 3 ... Housing

Claims (8)

A resin molded product having thermal conductivity and a main surface.
The resin molded product is a molded product of a resin composition containing a resin, a conductive heat conductive filler, and an insulating heat conductive filler.
The content of the conductive heat conductive filler is 10 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the resin.
The content of the insulating heat conductive filler is 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the resin.
When the arbitrary direction is the x direction and the direction orthogonal to the x direction is the y direction and the thickness direction of the resin molded product is the z direction on the main surface,
The thermal conductivity λx in the x direction, the thermal conductivity λy in the y direction, and the thermal conductivity λz in the z direction satisfy min (λx, λy) / λz ≧ 3, and
Electromagnetic wave shielding performance in frequencies 1GHz, which is measured according to KEC method is Ri der less 10 dB,
The temperature at which the resin shows the maximum value of the loss tangent measured by the dynamic viscoelasticity measurement at a frequency of 1 Hz and a strain of 0.3% with the first resin made of an olefin resin is −10 ° C. or lower. Resin molded body containing the resin of. The resin molded product according to claim 1, wherein the main surface is a flat surface or a curved surface. The resin molded product according to claim 1 or 2, wherein λx / λy satisfies 0.5 or more and 2 or less in the λx and the λy. The resin molded product according to any one of claims 1 to 3, wherein λx and λy satisfy max (λx, λy) ≧ 1 W / (m · K). The resin molded product according to any one of claims 1 to 4, wherein the conductive heat conductive filler has an aspect ratio of 3 or more. The resin molded product according to any one of claims 1 to 5, wherein the conductive heat conductive filler is made of a carbon material. The invention according to any one of claims 1 to 6, wherein the insulating heat conductive filler is composed of at least one selected from the group consisting of aluminum oxide, magnesium oxide, boron nitride and aluminum nitride. Resin molded body. The resin molded product according to any one of claims 1 to 7 , wherein the content of the second resin is 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the resin.

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