JP7255944B2 - Resin molding - Google Patents

Description

The present invention relates to resin moldings.

Electronic devices such as communication devices used indoors and outdoors, multi-information displays such as car navigation systems and smart meters, in-vehicle cameras, and in-vehicle ECUs may malfunction due to electromagnetic waves generated from the outside or inside. In order to prevent this malfunction, a metal plate, a conductive tape, or a conductive surface treated material such as plating, vapor deposition, or painting is used. However, when such materials are used, the cost is high and they cannot contribute to weight reduction of the product. Therefore, in recent years, a method of imparting electrical conductivity to the resin molded body to develop electromagnetic wave shielding properties has been used. It is In addition, electronic device parts are often required to have not only electrical conductivity but also flame retardancy, and a method of adding a flame retardant to a resin is used.

Patent Document 1 below discloses a resin composition containing 60 to 20% by mass of carbon black with respect to 40 to 80% by mass of thermoplastic resin. In the resin composition of Patent Document 1, a brominated organic phosphate flame retardant and antimony trioxide are added in order to improve flame retardancy.

Patent Document 2 below discloses a resin composition containing a polyethylene resin, a polystyrene-based thermoplastic elastomer, carbon black having a dibutyl phthalate oil absorption of 20 to 150 ml/100 g, and a phosphorus-based flame retardant. The phosphorus-based flame retardant is blended at a ratio of 30 to 50 parts by weight with respect to 100 parts by weight of the total amount of polyethylene resin, polystyrene thermoplastic elastomer, and carbon black. Further, Patent Document 2 describes that the volume resistivity of the resin composition is 1×10 ⁰ to 1×10 ⁹ Ω·cm.

Further, the following Patent Document 3 discloses a conductive polypropylene resin in-mold molded product composed of conductive polypropylene resin expanded particles. The expanded conductive polypropylene-based resin particles are formed by foaming a conductive polypropylene-based resin composition. Patent Document 3 describes that the conductive polypropylene-based resin composition contains 11 parts by weight or more and 25 parts by weight or less of conductive carbon black with respect to 100 parts by weight of the polypropylene-based resin. there is Further, Patent Document 3 describes that the volume resistivity value of the conductive polypropylene-based resin in-mold molded product is 10 Ω·cm or more and 5000 Ω·cm or less.

Patent No. 5038583 Patent No. 4925532 International Publication No. 2014/208397 Pamphlet

In recent years, with the speeding up of CPUs, higher conductivity than ever before is required. However, the resin compositions and molded articles of Patent Documents 1 to 3 still lack sufficient electrical conductivity. Moreover, as in Patent Document 1 and Patent Document 2, if a flame retardant such as a halogen-based flame retardant or a phosphorus-based flame retardant is contained, it is often not preferable from an environmental point of view.

An object of the present invention is to provide a resin molding that is excellent in both electrical conductivity and flame retardancy.

A resin molding according to the present invention is a resin molding containing a thermoplastic resin, carbon black, and plate-like graphite, wherein the carbon black has a DBP oil absorption of 160 ml/100 g or more and 800 ml/100 g or less. The content of the carbon black is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin, and the content of the plate-like graphite is 100 parts by weight of the thermoplastic resin On the other hand, it is 10 parts by weight or more and 200 parts by weight or less, and the volume resistivity of the resin molding is 1×10 ⁻² Ω·cm or more and less than 1×10 ⁰ Ω·cm.

In a specific aspect of the resin molded article according to the present invention, when the content of the carbon black is A parts by weight and the content of the plate-like graphite is B parts by weight, the carbon black and the plate-like graphite is 0.05 or more and 0.5 or less.

In another specific aspect of the resin molded article according to the present invention, the plate-like graphite has an aspect ratio of 10 or more and less than 300.

In still another specific aspect of the resin molding according to the present invention, the combustion rate measured according to the combustion standard UL94 HB is 40 mm/min or less.

In yet another specific aspect of the resin molding according to the present invention, a fibrous filler is further included. Preferably, the content of the fibrous filler is 1 part by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin.

In still another specific aspect of the resin molded article according to the present invention, the resin molded article has a main surface, and the main surface has an in-plane thermal conductivity of 1 W/(m·K) or more. .

In still another specific aspect of the resin molding according to the present invention, it is in the shape of a heat dissipation chassis, a heat dissipation housing, or a heat sink.

ADVANTAGE OF THE INVENTION According to this invention, the resin molding which is excellent in both electroconductivity and flame retardancy can be provided.

FIG. 4 is a schematic perspective view of a heat dissipation chassis; 3 is a schematic perspective view of a heat dissipation housing; FIG. It is a schematic perspective view of a heat sink shape.

The details of the present invention are described below.

The resin molding of the present invention contains a thermoplastic resin, carbon black, and plate-like graphite. The carbon black has a DBP oil absorption of 160 ml/100 g or more and 800 ml/100 g or less. The content of carbon black is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. The content of plate-like graphite is 10 parts by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. Further, the volume resistivity of the resin molding is 1×10 ⁻² Ω·cm or more and less than 1×10 ⁰ Ω·cm.

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

Also, the volume resistivity can be calculated from the resistivity correction coefficient and the thickness of the resin molding by measuring the resistance value using a low-resistance resistivity meter.

From the viewpoint of further increasing the electrical conductivity of the resin molded body, the resin molded body preferably has a volume resistivity of 5×10 ⁻¹ Ω·cm or less.

Based on the percolation theory that shows how carbon black, which is a conductive particle, is connected in the target substance, and the effect of improving the conductivity and gas barrier properties of plate-like graphite, the present inventors It was found that both flammability is exhibited.

Specifically, in the presence of a specific amount of carbon black having a DBP oil absorption in a specific range, when a specific amount of graphite material having a specific shape is contained, both conductivity and flame retardancy are effectively improved. found to be expressed.

Preferably, the resin molding of the present invention further contains a fiber diameter filler. When a fibrous filler is further included, both electrical conductivity and flame retardancy can be further improved. When a thermoplastic resin containing a fibrous filler is injected into a mold, for example, by injection molding, stress is applied to the fibrous filler, which deforms and solidifies in that state. When the molded product is melted, the residual stress is released. The dripping property, which is one of the flame-retardant factors, can be further improved by the springback phenomenon in which the entire molded product expands. In addition, when a fiber-based filler is contained, the orientation of the resin molding is further improved, and the electrical conductivity can be further improved.

The resin molding of the present invention preferably has a burning rate of 40 mm/min or less, more preferably 20 mm/min or less, as measured according to the combustion standard UL94 HB. In this case, the flame retardancy of the resin molding can be further enhanced.

In addition, since the resin molded article of the present invention contains plate-like graphite having high thermal conductivity, it is also excellent in heat dissipation.

In the present invention, the in-plane thermal conductivity of the main surface of the resin molded body is preferably 1 W/(m K) or more, more preferably 3 W/(m K) or more, further preferably 5 W/(m ·K) or more, particularly preferably 8 W/(m·K) or more. Although the upper limit of the thermal conductivity in the in-plane direction is not particularly limited, it is, for example, 50 W/(m·K).

In addition, the main surface may be a flat surface or a curved surface. Further, in the present invention, the main surface means a surface having the largest area among a plurality of surfaces on the outer surface of the resin molding, and means a continuous surface.

The in-plane thermal conductivity can be calculated using the following formula (1).

Thermal conductivity (W/(m·K)) = specific gravity (g/cm ³ ) x specific heat (J/g·K) x thermal diffusivity (mm ² /s) (1)

The thermal diffusivity can be measured, for example, using Netchi Japan Co., Ltd. product number "Xenon Flash Laser Analyzer LFA467 HyperFlash".

Since the resin molding of the present invention is excellent in all of flame retardancy, conductivity and heat dissipation, it can be used as a housing for electronic equipment such as communication equipment requiring electromagnetic wave shielding, smart meters and in-vehicle ECUs. It can be used preferably.

The resin molding of the present invention is preferably a molding of a resin composition containing a thermoplastic resin, carbon black and plate-like graphite. The resin molded article of the present invention can be obtained by molding the above resin composition by a method such as pressing, extrusion, extrusion lamination, or injection molding.

In the present invention, the volume average particle size of the plate-like graphite in the resin molding is preferably 5 µm or more, more preferably 30 µm or more, still more preferably 60 µm or more, preferably 500 µm or less, more preferably 350 µm or less, and even more preferably 350 µm or less. It is 300 μm or less. When the volume average particle size of the plate-like graphite is at least the above lower limit, the conductivity can be further enhanced. On the other hand, when the volume average particle size of the plate-like graphite is equal to or less than the above upper limit, the flame retardancy of the resin molding can be further enhanced. Two or more types of plate-like graphite having different volume average particle sizes may be used in combination.

In addition, in the present invention, the volume average particle size of plate-like graphite is based on JIS Z 8825: 2013, and a laser diffraction/scattering particle size distribution analyzer is used to calculate the volume-based distribution by a laser diffraction method. Say the value.

For example, plate-like graphite is put into a soapy water solution (neutral detergent: containing 0.01%) so that its concentration becomes 2% by weight, and ultrasonic waves are applied for 1 minute at an output of 300 W using an ultrasonic homogenizer. , to obtain a suspension. Next, the suspension is measured for the volume particle size distribution of the plate-like graphite by a laser diffraction/scattering particle size analyzer (manufactured by Nikkiso Co., Ltd., product name “Microtrac MT3300”). The cumulative 50% value of this volume particle size distribution can be calculated as the volume average particle size of the plate-like graphite.

In the present invention, the primary particle size of carbon black is preferably 34 nm or more, preferably 40 nm or more, preferably 50 nm or less, more preferably 45 nm or less. When the primary particle size of carbon black is within the above range, even lower carbon black content can provide higher electrical conductivity and flame retardancy.

The primary particle size of carbon black can be obtained, for example, using image data of carbon black obtained by a transmission electron microscope. The primary particle size of carbon black can be determined, for example, from the average primary particle size of 100 particles. As a transmission electron microscope, for example, the product name "JEM-2200FS" manufactured by JEOL Ltd. can be used.

The resin molding of the present invention may be in the shape of a heat dissipation chassis, a heat dissipation housing, or a heat sink.

FIG. 1 is a schematic diagram of a heat dissipation chassis. When the resin molded body is a heat radiating chassis, the main surface is the portion indicated by arrow A in FIG.

FIG. 2 is a schematic diagram of a heat dissipation housing. When the resin molding is a heat dissipation housing, the portion indicated by arrow B in FIG. 2 is the main surface. In addition, as shown in FIG.1 and FIG.2, the main surface may have unevenness|corrugation.

FIG. 3 is a schematic diagram of a heat sink shape. When the resin molding has a heat sink shape, the portion indicated by arrow C in FIG. 3 is the main surface. Specifically, the main surface on one side of the bottom plate portion and the surface of the fin portion are the main surfaces. Thus, multiple principal surfaces may exist.

The details of the materials constituting the resin molding of the present invention will be described below.

(Thermoplastic resin)
The thermoplastic resin is not particularly limited, and known thermoplastic resins can be used. Specific examples of thermoplastic resins include polyolefins, polystyrenes, polyacrylates, polymethacrylates, polyacrylonitrile, polyesters, polyamides, polyurethanes, polyethersulfones, polyetherketones, polyimides, polydimethylsiloxanes, polycarbonates, or at least two of these. Seed-containing copolymers, and the like. These thermoplastic resins may be used alone or in combination.

The 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 heat.

The polyolefin is not particularly limited, and known polyolefins can be used. Specific examples of polyolefins include polyethylene, which is an ethylene homopolymer, ethylene-α-olefin copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-acetic acid. Examples include polyethylene resins such as vinyl copolymers. In addition, the polyolefin is a propylene homopolymer such as polypropylene, a polypropylene-based resin such as a propylene-α-olefin copolymer, a butene homopolymer such as polybutene, butadiene, or a conjugated diene homopolymer or copolymer such as isoprene. and so on. 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.

Moreover, it is preferable that the polyolefin (olefin-based resin) contains an ethylene component. The content of the ethylene component is preferably 5% by mass to 40% by mass. When the content of the ethylene component is within the above range, it is possible to further improve the heat resistance while further improving the impact resistance of the resin molding.

(flat graphite)
The plate-like graphite is not particularly limited as long as it is plate-like graphite, and for example, graphite, expanded graphite, exfoliated graphite, graphene, or the like can be used. From the viewpoint of further enhancing flame retardancy and thermal conductivity, graphite or exfoliated graphite is preferred, and exfoliated graphite is more preferred. These may be used alone or in combination. In addition, in the present invention, the plate-like graphite may be scale-like graphite.

Expanded graphite is a known substance that expands when heated, and is produced by acid-treating powders of natural flake graphite, pyrolytic graphite, Kish graphite, etc. with a strong oxidizing agent to produce graphite intercalation compounds. Examples of strong oxidizing agents include inorganic acids such as concentrated sulfuric acid, nitric acid and selenic acid, concentrated nitric acid, perchloric acid, perchlorate, permanganate, bichromate and hydrogen peroxide. The expanded graphite is desirably a type of crystalline compound that maintains the layered structure of graphite.

Exfoliated graphite is obtained by exfoliating the original graphite, and refers to a graphene sheet laminate thinner than the original graphite. The exfoliation treatment for exfoliating graphite is not particularly limited, and either a mechanical exfoliation method using a supercritical fluid or the like or a chemical exfoliation method using an acid may be used. The number of laminated graphene sheets in exfoliated graphite should be less than that of the original graphite, but is preferably 1000 or less, more preferably 500 or less, and even more preferably 200 or less.

Plate-like graphite may be used individually by 1 type, and may use multiple types together. For example, expanded graphite and graphite different from expanded graphite may be used in combination. In this case, the graphite different from the expanded graphite may be flake graphite or exfoliated graphite. In this specification, expanded graphite means graphite different from expanded graphite, unless otherwise specified. Specifically, graphite different from expanded graphite is plate-like graphite having an expansion ratio of less than 10 ml/g. The expansion ratio can be measured, for example, by the following method.

First, the difference between the specific volume at room temperature (ml/g) and the specific volume after heating is evaluated, and 1 g of a thermal expansion material (expanded graphite) is put into a quartz beaker preheated to 700°C in an electric furnace, and quickly After being placed in an electric furnace heated to 700° C. for 1 minute, it is taken out and slowly cooled to room temperature. After that, the loose apparent specific gravity (g/ml) of the expanded material is measured, and the expansion ratio can be calculated as 1/loose apparent specific gravity.

The content of plate-like graphite is 10 parts by weight or more, preferably 70 parts by weight or more, more preferably 100 parts by weight or more, and 200 parts by weight or less, preferably 180 parts by weight or less, relative to 100 parts by weight of the thermoplastic resin. , more preferably 150 parts by weight or less. When the content of the plate-like graphite is at least the above lower limit, the electrical conductivity, flame retardancy and heat dissipation can be further enhanced. In addition, if the content of plate-like graphite is too large, the area of the interface that becomes the starting point of fracture increases, so if the content of plate-like graphite is the above upper limit or less, impact resistance can be further improved .

The aspect ratio of the plate-like graphite is preferably 5 or more, more preferably 10 or more, still more preferably 21 or more, preferably 2000 or less, more preferably 1000 or less, still more preferably less than 300, particularly preferably 100 or less. When the aspect ratio of the plate-like graphite is equal to or higher than the above lower limit, the heat dissipation in the planar direction can be further enhanced. Further, when the aspect ratio of the plate-like graphite is equal to or less than the above upper limit, the graphite particles themselves are less likely to bend in the thermoplastic resin during injection molding, for example. Therefore, it is possible to further improve the gas barrier performance and further improve the flame retardancy. In this specification, the aspect ratio refers to the ratio of the maximum dimension of the plate-like graphite in the stacking plane direction to the thickness of the plate-like graphite.

The shape and thickness of plate-like graphite can be measured using, for example, a transmission electron microscope (TEM) or a scanning electron microscope (SEM). From the viewpoint of making the observation easier, it is desirable to heat a test piece cut out from the resin molded body at 600° C. to blow off the resin and observe it with a transmission electron microscope (TEM) or a scanning electron microscope (SEM). . In addition, the test piece may be cut out along the direction along the main surface of the resin molded body as long as the thickness of the plate-like graphite can be measured by skipping the resin, or along the direction perpendicular to the main surface of the resin molded body. You can cut it out.

(Carbon black)
The carbon black has a DBP oil absorption of 160 ml/100 g or more, preferably 200 ml/100 g or more, and 800 ml/100 g or less, preferably 500 ml/100 g or less, more preferably 400 ml/100 g or less, and still more preferably 300 ml/100 g or less. 100 g or less. When the DBP oil absorption of carbon black is at least the above lower limit, the electrical conductivity and flame retardancy of the resin molding can be further enhanced. When the DBP oil absorption of carbon black is equal to or less than the above upper limit, aggregation during kneading can be prevented and stability can be further improved.

Examples of carbon black that can be used include oil furnace black such as ketjen black, acetylene black, channel black, and thermal black. Among them, oil furnace black is preferable from the viewpoint of further increasing the electrical conductivity of the resin molding. Carbon black may also contain metal impurities such as Fe and Ni.

The content of carbon black is 10 parts by weight or more, preferably 15 parts by weight or more, more preferably 20 parts by weight or more, and 100 parts by weight or less, with respect to 100 parts by weight of the thermoplastic resin. is 80 parts by weight or less, more preferably 50 parts by weight or less. When the content of carbon black is at least the above lower limit, the electrical conductivity and flame retardancy can be further enhanced. Moreover, when the content of carbon black is equal to or less than the above upper limit, the balance between conductivity, flame retardancy and impact resistance can be further improved.

In the present invention, when the content of carbon black is A parts by weight and the content of plate-like graphite is B parts by weight, the content ratio A/B between carbon black and plate-like graphite is preferably 0. 0.05 or more, more preferably 0.1 or more, preferably 0.5 or less, more preferably 0.3 or less. When the ratio A/B is within the above range, the electrical conductivity can be further enhanced.

(fibrous filler)
The resin molding of the present invention may further contain a fibrous filler. Examples of the fibrous filler include metal fibers, carbon fibers, cellulose fibers, aramid fibers, and glass fibers. These may be used alone or in combination.

Although the content of the fibrous filler is not particularly limited, it is preferably 1 part by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. When the content of the fibrous filler is within the above range, it is possible to impart even better fluidity to the resin composition when forming the resin molding.

The carbon fiber is not particularly limited, but PAN-based or pitch-based carbon fiber or the like can be used.

(Flame retardants)
Other flame retardants may be contained in the resin molding of the present invention. Other flame retardants include, but are not limited to, bromine compounds, phosphorus compounds, chlorine compounds, antimony compounds, metal hydroxides, nitrogen compounds, boron compounds, and the like.

Also, the content of the other flame retardant in the resin molded article of the present invention is not particularly limited, but for example, it is preferably 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. When the content of the other flame retardant is equal to or less than the above upper limit, it is more preferable from an environmental point of view.

In the present invention, high flame retardancy can be obtained even when the above-described halogen-based flame retardant or phosphorus-based flame retardant is not included or is added in a small amount. In addition, in the present invention, when used in combination with a flame retardant, even higher flame retardancy can be obtained than when the flame retardant is used alone.

(other additives)
Various additives may be added as optional components to the resin molding. Additives include, for example, phenol-based, phosphorus-based, amine-based, sulfur-based antioxidants; benzotriazole-based, hydroxyphenyltriazine-based UV absorbers; metal damage inhibitors; various fillers; stabilizers; pigments; These may be used alone or in combination.

(Manufacturing method of resin molding)
The resin molded article of the present invention can be produced, for example, by the following method.

First, a resin composition containing a thermoplastic resin, plate-like graphite, and carbon black is prepared. The resin composition may further contain the various materials described above. In the resin composition, carbon black is preferably dispersed in the thermoplastic resin. In this case, the electrical conductivity of the resulting resin molding can be further enhanced. The method of dispersing carbon black and plate-like graphite in the thermoplastic resin is not particularly limited, but the thermoplastic resin can be heated and melted and kneaded with carbon black and plate-like graphite to disperse them even more uniformly. can be done.

The kneading method is not particularly limited. and a method of kneading in. Among these, the method of melt-kneading using an extruder is preferable.

Next, a resin molded article can be obtained by molding the prepared resin composition by a method such as press working, extrusion, extrusion lamination, or injection molding.

As described above, in the resin molded article 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. In addition, the present invention is not limited to the following examples.

(Example 1)
100 parts by weight of polypropylene (PP) as a thermoplastic resin, 50 parts by weight of oil furnace black as carbon black, and 100 parts by weight of scaly graphite as plate-like graphite were added to Laboplastomill (manufactured by Toyo Seiki Co., Ltd., product number "R100") 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 molding of 100 mm long×100 mm wide×2 mm thick. In addition, as polypropylene, the trade name "BC10HRF" manufactured by Japan Polypropylene Corporation was used. As the oil furnace black, Lion's product name "EC200L" (DBP oil absorption: 300 ml/100 g, primary particle size: 41 nm) was used. As flake graphite, trade name “CPB-100” (average particle size: 100 μm) manufactured by Chuetsu Graphite Co., Ltd. was used.

(Example 2)
A resin molding was obtained in the same manner as in Example 1, except that the amount of carbon black added was 10 parts by weight.

(Example 3)
A resin molding was obtained in the same manner as in Example 1, except that the amount of carbon black added was 100 parts by weight.

(Example 4)
A resin molding was obtained in the same manner as in Example 1, except that the amount of flake graphite added was 10 parts by weight.

(Example 5)
A resin molding was obtained in the same manner as in Example 1, except that the amount of flake graphite added was 200 parts by weight.

(Example 6)
Resin molding was performed in the same manner as in Example 1, except that an oil furnace black having a DBP oil absorption of 495 ml/100 g and a primary particle size of 34 nm (manufactured by Lion Corporation, trade name "EC600JD") was used as the carbon black. got a body

(Example 7)
Resin molding was performed in the same manner as in Example 1, except that an oil furnace black having a DBP oil absorption of 365 ml/100 g and a primary particle size of 40 nm (manufactured by Lion Corporation, trade name "EC300J") was used as the carbon black. got a body

(Example 8)
As the carbon black, an oil furnace black having a DBP oil absorption of 180 ml/100 g and a primary particle size of 30 nm (manufactured by Asahi Carbon Co., Ltd., trade name "F-200GS") was used in the same manner as in Example 1. to obtain a resin molded body.

(Example 9)
Resin was prepared in the same manner as in Example 1, except that acetylene black (manufactured by Denka Co., Ltd., trade name "Li-400") having a DBP oil absorption of 177 ml / 100 g and a primary particle size of 48 nm was used as the carbon black. A compact was obtained.

(Example 10)
A resin molding was obtained in the same manner as in Example 1, except that flake graphite with an average particle size of 7 μm (manufactured by Ito Graphite Co., Ltd., trade name “PC-H”) was used.

(Example 11)
A resin molding was obtained in the same manner as in Example 1, except that flake graphite with an average particle size of 300 μm (manufactured by Chuetsu Graphite Co., Ltd., trade name “CPB-80”) was used.

(Example 12)
A resin molded body was produced in the same manner as in Example 1, except that exfoliated graphite having an average particle size of 30 μm (manufactured by Nippon Graphite Co., Ltd., trade name “UP-35N”) was used instead of flake graphite as the plate-like graphite. Obtained.

(Example 13)
A resin molding was obtained in the same manner as in Example 1, except that exfoliated graphite having an average particle size of 100 μm (manufactured by ITEC Co., Ltd., trade name “iGrafen-α”) was used instead of flake graphite as the plate-like graphite. rice field.

(Example 14)
Exfoliated graphite with an average particle size of 300 μm (manufactured by Chuetsu Graphite Co., Ltd., trade name “BSP-300AK”) was used as plate-shaped graphite instead of flake graphite. got

(Example 15)
100 parts by weight of polypropylene (PP) as a thermoplastic resin, 50 parts by weight of oil furnace black as carbon black, 100 parts by weight of flake graphite as plate-like graphite, and 100 parts by weight of glass fiber as a fiber-based filler in a laboratory. A resin composition was obtained by melt-kneading at 200° C. using a plastomill (manufactured by Toyo Seiki Co., Ltd., product number “R100”). 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 molding of 100 mm long×100 mm wide×2 mm thick. As the polypropylene, trade name "BC10HRF" manufactured by Japan Polypropylene Corporation was used. As the oil furnace black, Lion's product name "EC200L" (DBP oil absorption: 300 ml/100 g, primary particle size: 41 nm) was used. As flake graphite, trade name “CPB-100” (average particle size: 100 μm) manufactured by Chuetsu Graphite Co., Ltd. was used. As the glass fiber, the trade name “ECS03T-480” (E glass, diameter: 13 μm, fiber length: 3 mm) manufactured by Nippon Electric Glass Co., Ltd. was used.

(Example 16)
A resin molding was obtained in the same manner as in Example 15, except that the glass fiber as the fibrous filler was 10 parts by weight.

(Example 17)
A resin molding was obtained in the same manner as in Example 15, except that 200 parts by weight of glass fiber was used as the fiber-based filler.

(Example 18)
Except for using a copper fiber filler (manufactured by Nijigi Co., Ltd., trade name “KC Metal Fiber C1100”, diameter: 60 μm, fiber length: 3 mm) manufactured by chatter vibration cutting method instead of glass fiber as the fiber filler. obtained a resin molding in the same manner as in Example 15.

(Example 19)
A resin molding was obtained in the same manner as in Example 1, except that expanded graphite having an average particle size of 200 μm (trade name “EXP-80S220” manufactured by Fuji Graphite Co., Ltd.) was used as the plate-like graphite.

(Example 20)
As plate-like graphite, 50 parts by weight of flake graphite with an average particle size of 100 μm (manufactured by Chuetsu Graphite Industry Co., Ltd., trade name “CPB-100”) and expanded graphite with an average particle size of 200 μm (manufactured by Fuji Graphite Industry Co., Ltd., trade name “ A resin molding was obtained in the same manner as in Example 1, except that 50 parts by weight of EXP-80S220") was used.

(Example 21)
Exfoliated graphite with an average particle size of 100 μm (manufactured by ITEC Co., Ltd., trade name “iGrafen-α”) and expanded graphite with an average particle size of 200 μm (manufactured by Fuji Graphite Industry Co., Ltd., trade name “ EXP-80S220") was used, and a resin molding was obtained in the same manner as in Example 16 as shown in Table 2 below, except that 50 parts by weight was used.

(Comparative example 1)
A resin molding was obtained in the same manner as in Example 1, except that the amount of carbon black added was 5 parts by weight.

(Comparative example 2)
A resin molding was obtained in the same manner as in Example 2, except that the amount of flake graphite added was 5 parts by weight.

(Comparative Example 3)
Example 4 was repeated except that 10 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "HS-100", DBP oil absorption: 140 ml/100 g, primary particle size: 48 nm) was used as carbon black. to obtain a resin molded body.

(Comparative Example 4)
Resin molding was performed in the same manner as in Example 2, except that 100 parts by weight of talc (manufactured by Nippon Talc Co., Ltd., trade name “MS-P”, primary particle size 15 μm) was used as a plate-like filler instead of plate-like graphite. got a body

(Evaluation method)
The resin moldings obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2 below.

<Volume resistivity>
Measurement was performed at room temperature in the atmosphere using a four-probe resistivity measuring device (Loresta AX MCP-T370, manufactured by Mitsubishi Chemical Corporation).

<Flame Retardant>
Combustibility of the resin molding was evaluated according to UL94 HB test. Specifically, a test piece was prepared by cutting the resin molded body into a rectangular shape in plan view into a size of 125 mm in length×13 mm in width×2.0 mm in thickness. A straight marked line L1 extending in the width direction at a point 25 mm away in the length direction from one side edge in the length direction of the test piece, and a point 100 mm away from the one side edge in the length direction in the width direction Extending linear marked lines L2 are attached respectively. After that, this test piece was held horizontally, and a flame with a crater inner diameter of 20 mm was applied to the central portion in the width direction of one side end of the test piece for 30 seconds. The burning speed was calculated from the arrival time from when the flame reached any part of the marked line L1 to when the flame progressed in the length direction of the test piece and reached any part of the marked line L2. . Those that did not spread to the marked line L1 and those that were extinguished before reaching the marked line L2 were described as a burning speed of 0 mm.

Also, the combustibility of the resin molding was measured according to the UL94 V test. Specifically, a test piece is prepared by cutting a resin molded body into a rectangular shape in plan view to have a length of 125 mm × width of 13 mm × thickness of 1.5 mm, and the combustibility of the test piece (resin molded body) is evaluated. evaluated. The UL94 V test was evaluated with V0, V1, and V2, and not applicable was described as not applicable.

<Drip property>
Evaluation of drip properties was performed in accordance with the UL94V vertical burning test. Evaluation criteria are shown below.
◎…Drip does not occur and fire does not spread 〇…Drip does not occur △…Drip occurs but surgical cotton does not burn ×…Drip occurs and surgical cotton burns

<In-plane thermal conductivity (W/(mK))>
The thermal conductivity in the in-plane direction (in-plane thermal conductivity) was measured using a product number "Xenon Flash Laser Analyzer LFA467 HyperFlash" manufactured by Netsch Japan. Specifically, a measurement sample was obtained by punching out a 10 mm long, 2 mm wide, and 2 mm thick resin molded body molded into a size of 100 mm long, 100 mm wide, and 2 mm thick by the method described in Examples and Comparative Examples. A measurement sample was fitted into a holder in a direction that allows measurement of in-plane thermal conductivity, thermal diffusivity at 30° C. was measured, and thermal conductivity was calculated according to the following formula (1).

Thermal conductivity (W/(m·K)) = specific gravity (g/cm ³ ) x specific heat (J/g·K) x thermal diffusivity (mm ² /s) (1)

Claims (7)

A resin molding containing a thermoplastic resin, carbon black, and plate-like graphite,
The carbon black has a DBP oil absorption of 160 ml/100 g or more and 800 ml/100 g or less,
The content of the carbon black is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin,
The content of the plate-like graphite is 10 parts by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin,
The resin molding has a volume resistivity of 1×10 ⁻² Ω·cm or more and less than 1×10 ⁰ Ω·cm ,
A resin molding having the shape of a heat dissipation chassis, a heat dissipation housing, or a heat sink . When the content of the carbon black is A parts by weight and the content of the plate-like graphite is B parts by weight, the content ratio A/B between the carbon black and the plate-like graphite is 0.05 or more. , is 0.5 or less. The resin molded article according to claim 1 or 2, wherein the plate-like graphite has an aspect ratio of 10 or more and less than 300. The resin molding according to any one of claims 1 to 3, which has a combustion rate of 40 mm/min or less as measured according to combustion standard UL94 HB. The resin molding according to any one of claims 1 to 4, further comprising a fibrous filler. 6. The resin molding according to claim 5, wherein the content of said fibrous filler is 1 part by weight or more and 200 parts by weight or less with respect to 100 parts by weight of said thermoplastic resin. The resin molding has a main surface,
The resin molding according to any one of claims 1 to 6, wherein the main surface has an in-plane thermal conductivity of 1 W/(m·K) or more.

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