JP5415058B2 - Thermally conductive resin composition and molded body comprising the same - Google Patents

Description

  The present invention relates to a resin composition containing a polyamide resin, boron nitride, and aramid fiber and excellent in thermal conductivity, insulation, impact resistance, and heat resistance, and a molded article comprising the same.

  Conventionally, as raw materials for molding, resins such as polypropylene (PP), ABS, polyamide (PA6, PA66, etc.), polyester (PET, PBT, etc.), polycarbonate (PC), etc. are known. Resins such as liquid crystal polyester (LCP) and polyphenylene sulfide (PPS), which have excellent mechanical strength, chemical resistance, and processability, are widely used in various electronic devices, electronic parts, mechanical parts, etc. I came.

  On the other hand, in recent electronic devices, with higher performance, smaller size and lighter weight, heat countermeasures that effectively dissipate the heat generated by various electronic components to the outside has become a very important issue. There is a growing demand for improvement in heat dissipation of resin molding materials that are constituent materials. Conventionally, as a means of improving the heat dissipation of the resin molding material, a filler material having high thermal conductivity (boron nitride, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon carbide, graphite, etc.) is blended. The method is known. For example, Patent Document 1 describes a thermally conductive resin molded product in which a thermoplastic resin is filled with graphite powder, and Patent Document 2 describes a resin heat radiation plate in which polyphenylene sulfide resin is filled with magnesium oxide or aluminum oxide. . However, in order to obtain a highly thermally conductive resin composition, it is necessary to add a large amount of filler, which results in extremely low impact resistance and a very brittle material. When the material is blended, there is a problem that the insulating property is lowered and the use is limited.

As a method for improving the impact resistance of a resin composition in which a large amount of such a filler is added, the addition of an impact resistance improver has been proposed. For example, Patent Document 3 discloses heat conduction with a polycarbonate resin. It describes that an elastomer is compounded as an impact resistance improver in a resin composition comprising a conductive filler. However, although it is described in the Examples that a core / shell type impact resistance improver having a core of butadiene / styrene and a shell of acrylic as an elastomer is added, there is no specific description about improvement of impact resistance.
Patent Document 4 proposes a resin composition excellent in impact resistance and thermal conductivity, comprising an impact modifier containing a rubber-reinforced resin and / or an olefin resin, graphite particles and an elastomer component. However, there is a problem that heat resistance is lowered by adding an elastomer component in addition to a rubber-reinforced resin or an olefin resin.
In addition, as a method for improving the impact resistance of a resin, addition of a fibrous reinforcing material such as glass fiber or carbon fiber is known, but for a resin composition in which a large amount of filler is added. No impact resistance improving effect was obtained.
JP-A-62-131033 JP 2001-151905 A JP 2007-99798 A JP 2007-238917 A

  The present invention solves the above-mentioned problems and provides a resin composition excellent in thermal conductivity, insulation, impact resistance and heat resistance, and a molded product obtained therefrom.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by blending polyamide resin, boron nitride, and aramid fibers at a specific ratio, The present invention has been reached.
That is, the gist of the present invention is as follows.
(1) It contains polyamide resin (A), boron nitride (B), and aramid fiber (C), and the polyamide resin is nylon 12 or nylon 6, and the polyamide resin (A) and boron nitride (B) Mass ratio (A / B) is 15/85 to 60/40, and the content of the aramid fiber (C) is 100 parts by mass in total of the polyamide resin (A) and boron nitride (B). 3 to 20 parts by mass of a heat conductive resin composition.
(2) Thermal conductivity is 5 W / m · K or higher, volume resistivity is 10 ¹⁰ Ωcm or higher, notched Izod impact strength is 60 J / m or higher, and deflection temperature under load of 1.8 MPa is 100 ° C. or higher. (1) The resin composition as described above.
(3) The resin composition according to (1) or (2), wherein the boron nitride (B) has a scale-like shape having a hexagonal crystal structure having an average particle diameter of 1 to 200 μm.
(4) The resin composition according to any one of (1) to (3), wherein the average fiber length of the aramid fiber (C) is 1 to 15 mm.
(5) A thermally conductive resin molded article obtained by molding the resin composition according to any one of (1) to (4).

  ADVANTAGE OF THE INVENTION According to this invention, the resin composition excellent in thermal conductivity, insulation, impact resistance, and heat resistance, and the molded object obtained from it are provided.

Hereinafter, the present invention will be described in detail.
The polyamide resin (A) used in the present invention must be polydodecamide (nylon 12) or polycoupler (nylon 6).

  The relative viscosity of the polyamide resin (A) used in the present invention is not particularly limited, but the relative viscosity measured with 96 mass% concentrated sulfuric acid as a solvent at a temperature of 25 ° C. and a concentration of 1 g / dl is 1.6. It is preferably in the range of ˜2.8. If the relative viscosity is less than 1.6, mechanical properties and heat resistance may be inferior when formed into a molded body. On the other hand, if it is larger than 2.8, the molding processability decreases due to the high viscosity.

  The resin composition of the present invention contains boron nitride (B). By containing boron nitride (B), thermal conductivity can be improved without reducing the insulating properties of the resin composition. The mass ratio (A / B) of the polyamide resin (A) and boron nitride (B) needs to be 15/85 to 60/40, and is preferably 30/70 to 50/50. If the blending amount of boron nitride (B) is less than 40% by mass, sufficient thermal conductivity may not be obtained, and if it exceeds 85% by mass, the fluidity will decrease and the load during molding will increase. The operability may be reduced.

The average particle size of boron nitride is preferably 1 to 200 μm, and more preferably 5 to 100 μm. If the average particle size is less than 1 μm, agglomerates are likely to occur due to poor dispersion, and a uniform molded product cannot be obtained, resulting in a decrease in mechanical properties and variations in thermal conductivity. When the average particle size exceeds 200 μm, it becomes difficult to fill the resin composition at a high concentration, and the surface of the molded product may become rough.
The crystal system of boron nitride is not particularly limited, and boron nitride having any crystal structure such as hexagonal system, cubic system, and the like is applicable. Of these, boron nitride having a hexagonal crystal structure is preferable because of its high thermal conductivity.
Examples of the form of boron nitride (B) include a spherical shape, a powder shape, a fiber shape, a needle shape, a scale shape, a whisker shape, a microcoil shape, and a nanotube shape. Since it becomes easy to orient in a surface direction when it is set as a molded body and, as a result, thermal conductivity can be increased, the form of boron nitride (B) is preferably scaly.

  Boron nitride (B) improves adhesion to the polyamide resin (A), so that silane coupling agents, titanium coupling agents, etc., for example, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) are used. ) -Γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyldimethoxymethylsilane, and other aminosilanes, γ-glycidoxypropyltrimethoxysilane, γ-glycididoxypropylethoxysilane, Epoxysilanes such as β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, isopropyltristearoyl titanate, isopropyltridodecylbenzenesulfonyl titanate, titanium-based coupling agents such as tetraisopropylbis (dioctylphosphite) titanate, etc. Mosquito Surface treatment may be performed with a pulling agent. These may be used alone or in combination.

  The aramid fiber (C) used in the present invention is a wholly aromatic polyamide fiber, and a para-aramid fiber and a meta-aramid fiber are known. Any of them is preferably used in the present invention, but para-aramid fibers that have low heat shrinkage, high heat resistance, and high strength are particularly preferable. Examples of the para-aramid fiber include polyparaphenylene terephthalamide fiber (trade name “Kevlar” manufactured by Toray DuPont, trade name “Twaron” manufactured by Toray Techno Products Co., Ltd.), copolyparaphenylene-3,4′- Examples of oxydiphenylene terephthalamide fibers (manufactured by Teijin Techno Products, trade name “Technola”) and meta-aramid fibers include polymetaphenylene isophthalamide fiber (manufactured by DuPont, USA, trade name “NOMEX”, Teijin Techno). Commercial products such as those manufactured by Products (trade name “Conex”) can be used. Aramid resins may be used alone or in appropriate combination of two or more.

The average fiber length of the aramid fiber (C) is preferably 1 to 15 mm, and more preferably 2 to 10 mm. If the average fiber length is less than 1 mm, a sufficient impact resistance improving effect cannot be obtained. The longer the average fiber length, the greater the impact resistance improving effect. However, if the average fiber length exceeds 15 mm, the fluidity is greatly lowered, which is not preferable in terms of moldability.
The average fiber diameter of the aramid fiber (C) is preferably 1 to 50 μm, and more preferably 3 to 25 μm. If the fiber diameter is less than 1 μm, a sufficient impact resistance improving effect cannot be obtained, and if the fiber diameter exceeds 50 μm, it is not preferable in terms of moldability.

  In the resin composition of the present invention, the content of the aramid fiber (C) needs to be 3 to 20 parts by mass with respect to 100 parts by mass in total of the polyamide resin (A) and boron nitride (B). Yes, preferably 7 to 15 parts by mass. If the content of the aramid fiber (C) is less than 3 parts by mass, a sufficient reinforcing effect cannot be obtained. When the blending amount of the aramid fiber (C) exceeds 20 parts by mass, the fluidity is lowered and the moldability is deteriorated. In addition, the fiber floats on the surface at the time of molding, and the appearance may be deteriorated.

In the resin composition of the present invention, the pigment, heat stabilizer, antioxidant, weathering agent, flame retardant, plasticizer, lubricant, mold release agent, antistatic agent, filler, A crystal nucleus material or the like can be added.
Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like.
As the flame retardant, a halogen-based flame retardant, a phosphorus-based flame retardant, and an inorganic flame retardant can be used. However, in consideration of the environment, it is desirable to use a non-halogen flame retardant. Non-halogen flame retardants include phosphorus flame retardants, hydrated metal compounds (aluminum hydroxide, magnesium hydroxide, etc.), nitrogen-containing compounds (melamine-based, guanidine-based), inorganic compounds (borates, Mo compounds, etc.) Is mentioned.
Inorganic fillers include talc, layered silicate, calcium carbonate, zinc carbonate, wollastonite, silica, calcium silicate, graphite, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, trioxide Antimony, zeolite, hydrotalcite and the like can be mentioned. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran, and modified products thereof.
Examples of the inorganic crystal core material include talc and kaolin. Examples of the organic crystal core material include a sorbitol compound, benzoic acid and a metal salt of the compound, a phosphate metal salt, and a rosin compound.
In addition, the method of mixing these with the heat conductive resin composition of this invention is not specifically limited.

  Further, in the resin composition of the present invention, polyethylene, polypropylene, polybutadiene, polystyrene, AS resin, ABS resin, poly (acrylic acid), poly (acrylic acid ester), as long as it does not depart from the spirit of the present invention. Resins such as poly (methacrylic acid), poly (methacrylic acid ester), polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and copolymers thereof may be added.

  In the present invention, a fibrous filler other than the aramid fiber (C) can be blended in order to further improve various properties such as mechanical strength and heat resistance. Specific examples of fibrous fillers other than aramid fibers (C) include glass fibers, carbon fibers, graphitized carbon fibers, metal fibers, silica fibers, silica / alumina fibers, zirconia fibers, silicon nitride fibers, boron fibers, titanium. Examples thereof include potassium acid fiber and natural fiber represented by kenaf, and glass fiber and carbon fiber are preferable. Glass fiber is excellent in mechanical properties, heat resistance, and cost. Carbon fiber can further increase the thermal conductivity of the resin composition in addition to mechanical properties and heat resistance. These fibrous fillers can be used alone or in combination of two or more.

  The resin composition of the present invention comprises a polyamide resin (A), boron nitride (B), and aramid fiber (C), and further various additives as required. It can be produced by melt kneading using a machine, a twin screw extruder, a roll kneader, a Brabender or the like. At this time, it is also effective to use a static mixer or a dynamic mixer together. In order to improve the kneading state, it is preferable to use a twin screw extruder. The method for adding boron nitride (B) and aramid fiber (C) is not particularly limited, but can be added from a hopper or using a side feeder in an extruder. In addition, boron nitride (B) and aramid fiber (C) can be masterbatched to be diluted with a base resin during molding and used.

The resin composition of the present invention contains a polyamide resin (A), boron nitride (B), and aramid fiber (C) at a specific mass ratio, and the thermal conductivity thereof is the target final product. However, it can be set to 5 W / m · K or more, further 7 W / m · K or more. Similarly, the volume resistivity of the resin composition can be 10 ¹⁰ Ωcm or more, more preferably 10 ¹² Ωcm or more, and the notched Izod impact strength should be 60 J / m or more, further 70 J / m or more. The deflection temperature under a load of 1.8 MPa can be 100 ° C. or higher, and further 140 ° C. or higher.
The resin composition having such thermal conductivity, insulation, impact strength, and deflection temperature under load is suitably used in fields where high heat dissipation, light weight and energy saving are expected, such as home appliance / OA equipment field and automobile field. be able to.

  The resin composition of the present invention can be molded into a desired shape using a generally known melt molding method such as injection molding, compression molding, extrusion molding, transfer molding, or sheet molding to form a molded body.

  Specific examples of the molded body formed by molding the resin composition of the present invention include semiconductor elements, sealing materials such as resistors, connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, computer-related parts, etc.・ For releasing heat from electronic parts, VTR, TV, iron, air conditioner, stereo, vacuum cleaner, refrigerator, rice cooker, lighting equipment, etc. Lighting equipment parts such as heat radiating members, lamp sockets, lamp reflectors, lamp housings, acoustic product parts such as compact discs, laser discs, speakers, optical cable ferrules, mobile phone, fixed telephones, facsimiles, communication equipment parts such as modems, separation claws , Copiers such as heater holders, printing press related parts, impellers, Machine parts such as fan gears, gears, bearings, motor parts and cases, automotive mechanism parts, engine parts, parts in the engine room, electrical parts, interior parts, etc., microwave cooking pans, heat-resistant dishes, etc. Examples include cooking utensils, aircraft, spacecraft, space equipment parts, sensor parts, and the like. Moreover, since it is excellent in electrical insulation, it can be applied to a wiring board or the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited only to an Example. The measuring method used for evaluation of the resin composition of an Example and a comparative example is as follows.
(1) Flexural strength, flexural modulus:
In accordance with ASTM standard D-790, a load was applied at a deformation rate of 1 mm / min, and the bending strength and bending elastic modulus were measured.
(2) Impact strength:
In accordance with ASTM standard D-256, Izod impact strength was measured using a notched specimen.
(3) Deflection temperature under load (DTUL):
Based on ASTM standard D-648, the heat distortion temperature was measured at a load of 1.8 MPa.
(4) Thermal conductivity:
The thermal conductivity λ was calculated by the following formula as a product of the thermal diffusivity α, the density ρ, and the specific heat Cp obtained by the following method.
λ = αρCp
λ: Thermal conductivity (W / m · K)
α: Thermal diffusivity (m ² / sec)
ρ: Density (g / m ³ )
Cp: Specific heat (J / g · K)
The thermal diffusivity α was measured by a laser flash method using a laser flash method thermal constant measuring device TC-7000 (manufactured by ULVAC-RIKO) with respect to the resin flow direction of the bending test piece prepared in (1).
The density ρ was measured using an electronic hydrometer ED-120T (manufactured by Mirage Trading Co.).
The specific heat Cp was measured using a differential scanning calorimeter DSC-7 (manufactured by Perkin Elmer) under the condition of a temperature rising rate of 10 ° C./min.
(5) Insulation:
Based on ASTM standard D-257, the volume resistivity was measured, and 10 ¹⁰ Ωcm or more was evaluated as “◯” and less than 10 ¹⁰ Ωcm as “X”.

The raw materials used in Examples and Comparative Examples of the present invention are shown below.
(1) Resin / PA12: Polyamide 12 (Rilsan AMN manufactured by Arkema, relative viscosity 2.3, density 1.01 g / cm ³ )
PA6: Polyamide 6 (Unitika A1030BRL, relative viscosity 2.6, density 1.13 g / cm ³ )
PP: polypropylene (MA1B manufactured by Nippon Polypro Co., Ltd., density 0.9 g / cm ³ )
LCP: Liquid crystalline polyester (A5000, Ueno Pharmaceutical Co., Ltd., density 1.41 g / cm ³ )
(2) Thermally conductive filler / BNA: Hexagonal scaly boron nitride (SGP manufactured by Electrochemical Co., Ltd., average particle size 15 μm, density 2.26 g / cm ³ )
BNB: Hexagonal scaly boron nitride (Boronid S9 made by ESK, average particle size 9 μm, density 2.26 g / cm ³ )
Gr: scaly graphite (CB 150 manufactured by Nippon Graphite Industry Co., Ltd., average particle size 40 μm, density 2.25 g / cm ³ )
(3) Aramid fiber / AR1: Copolyparaphenylene-3,4′-oxydiphenylene terephthalamide fiber (Technola manufactured by Teijin Techno Products, average fiber diameter 12 μm, average fiber length 3 mm)
AR2: Copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber (Technola manufactured by Teijin Techno Products, average fiber diameter 12 μm, average fiber length 1 mm)
AR3: Copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber (Technola manufactured by Teijin Techno Products, average fiber diameter 12 μm, average fiber length 0.5 mm)
AR4: Polyparaphenylene terephthalamide fiber (Twaron manufactured by Teijin Techno Products, average fiber diameter 12 μm, average fiber length 3 mm)
AR5: Meta-aramid fiber (Conex, manufactured by Teijin Techno Products, average fiber diameter of 12 μm, average fiber length of 1 mm)
(4) Elastomer / SEBS: Styrene-butadiene hydrogenated polymer (Tuftec M1943 manufactured by Asahi Kasei Chemicals)
(5) Fibrous filler / GF: Glass fiber (JAFT692, manufactured by Owens Corning, average fiber diameter 10 μm, average fiber length 3 mm)

Example 1
A product obtained by dry blending 36 parts by mass of polyamide 12 resin (PA12) and 64 parts by mass of boron nitride (BNA) is supplied to a main hopper of a twin-screw extruder (Toshiba Machine: TEM26SS, screw diameter 26 mm) at 260 ° C. And melted. On the way, 10 parts by mass of aramid fiber (AR1) was supplied from the side feeder, sufficiently melted and kneaded, extruded into a strand shape, cooled and solidified, and then cut into a pellet shape to obtain a resin composition.
After sufficiently drying the obtained resin composition, using an injection molding machine (manufactured by Toshiba Machine: EC-100 type), cylinder temperature 260 ° C., mold temperature 100 ° C., injection time 20 seconds, cooling time 10 seconds. A molded body for evaluation was obtained by injection molding. Each evaluation was performed using the obtained molded object. The results are shown in Table 1.

Examples 2-14, Comparative Examples 1-12
A resin composition was obtained in the same manner as in Example 1 except that the polyamide resin (A), boron nitride (B), aramid fiber (C) and other resins and fillers were changed to the types and amounts shown in Table 1, respectively. This was injection molded to measure various physical properties. The evaluation results are summarized in Table 1. The glass fibers were supplied from the middle by the side feeder in the same manner as the aramid fibers, and the other raw materials were dry blended and supplied from the main hopper and melt kneaded.

As is clear from Table 1, in Examples 1 to 14, the polyamide resin (A), boron nitride (B), and aramid fiber (C) were blended at specific ratios, so that thermal conductivity, insulation, and impact resistance were obtained. Resin composition excellent in heat resistance and heat resistance was obtained.
On the other hand, in Comparative Examples 1-4, since the aramid fiber (C) was not blended or the blending amount was small, the resulting resin composition had low impact resistance. In Comparative Example 5, since the amount of the aramid fiber (C) was too large, kneading could not be performed and a resin composition could not be obtained.
In Comparative Example 6, since boron nitride (B) was not blended, the obtained resin composition had low thermal conductivity. In Comparative Example 7, when scaly graphite was blended instead of boron nitride (B), the thermal conductivity and impact resistance were high, but the conductivity was high.
In Comparative Example 8, when glass fiber was blended instead of the aramid fiber (C), the resulting resin composition had low impact resistance. In Comparative Examples 9 and 10, when a styrene-butadiene hydrogenated polymer was blended in place of the aramid fiber (C), the resin composition not only obtained the impact resistance improvement effect, but also decreased the bending strength. Oops.
In Comparative Examples 11 and 12, since a polypropylene resin or a liquid crystal polyester resin was used as the base resin instead of the polyamide resin (A), the effect of reinforcing the aramid fiber (C) was not sufficiently obtained, and the impact resistance of the resin composition Was low.

Claims (5)

The polyamide resin (A), boron nitride (B), and aramid fiber (C) are contained, the polyamide resin is nylon 12 or nylon 6, and the mass of the polyamide resin (A) and boron nitride (B) The ratio (A / B) is 15/85 to 60/40, and the aramid fiber (C) content is 3 to 100 parts by mass in total of the polyamide resin (A) and boron nitride (B). A heat conductive resin composition characterized by being 20 parts by mass. The thermal conductivity is 5 W / m · K or more, the volume resistivity is 10 ¹⁰ Ωcm or more, the notched Izod impact strength is 60 J / m or more, and the deflection temperature under load of 1.8 MPa is 100 ° C. or more. The resin composition according to claim 1. 3. The resin composition according to claim 1, wherein the boron nitride (B) has a scale-like shape having a hexagonal crystal structure having an average particle diameter of 1 to 200 μm. The resin composition according to any one of claims 1 to 3, wherein an average fiber length of the aramid fiber (C) is 1 to 15 mm. The heat conductive resin molded object formed by shape | molding the resin composition in any one of Claims 1-4.