JP4938997B2 - Molding resin with excellent electrical insulation and thermal conductivity - Google Patents

Description

  The present invention relates to a resin for molding that is electrically insulating and excellent in thermal conductivity, and relates to applications such as electricity, electronic parts, and automobile electrical parts that require heat dissipation and electrical insulation.

  Polyamide resins are widely used as molding materials in various fields such as various electric / electronic parts and automobile parts because of their excellent mechanical strength, heat resistance, wear resistance, and chemical resistance.

  However, the heat conductivity of polyamide resin is generally low, and heat dissipation of electronic components accompanied by heat generation cannot be performed, and the function may be impaired.

  In particular, in the electric / electronic parts field, electrical insulation is often required, and therefore electrical insulation is required along with improvement in the thermal conductivity of resin materials.

  Improvement of the thermal conductivity of resin materials is generally improved by blending inorganic fillers such as alumina and silica, and thermal conductive materials such as carbon fibers, graphite, and low contact point alloys, either alone or in combination with matrix resins. Has been tried.

  However, carbon fibers, graphite, low melting point alloys, and the like are electrically conductive, so that their electrical insulation is impaired and their use is limited.

  Alumina and silica, on the other hand, are electrically insulative, but their thermal conductivity is not so high, and high packing is necessary to achieve high thermal conductivity. Close-packing is done by combining different things. However, when the filling is high, the fluidity of the resin is extremely deteriorated and it is difficult to compound or mold the resin.

  When a fine layered filler is used in combination, the fluidity is further deteriorated, which is an obstacle to improving the thermal conductivity.

  Further, the reason why the thermal conductivity of the alumina blend is small is that the low thermal conductivity of the matrix resin is the rate-determining factor, which hinders the thermal conductivity of the resin composition. Therefore, attempts have been made to increase the thermal conductivity of the resin itself, but no effective one has been obtained.

  Attempts have been made to improve the thermal conductivity of the matrix resin layer by using a fine layered filler together. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-256147), thermal conductivity is improved by melt-mixing a plate-like filler having an average thickness of 0.5 μm or more in combination with 2 to 20 wt% spherical alumina. However, fine dispersion at the molecular level is difficult by melt kneading with a machine. Therefore, when the amount of the plate filler added is small, the effect of improving the thermal conductivity is small, and when the amount added is large, the fluidity of the resin is hindered and high filling cannot be achieved, resulting in a good heat conductive material. Cannot be obtained.

  Fine dispersion of a layered silicate in a polyamide resin for the purpose of preventing strength, heat resistance, toughness, etc. is disclosed in Patent Document 2 (International Patent Publication WO98 / 49235) and Patent Document 3 (Japanese Patent Laid-Open No. 2000-212432). However, all are related to strength and heat resistance, and there is no description about heat conduction.

JP 2002-256147 A International Patent Publication WO98 / 49235 JP 2000-212432 A

  The problem to be solved by the present invention is to provide a highly thermally conductive resin having electrical insulation and excellent thermal conductivity in applications requiring heat dissipation and electrical insulation, such as electricity, electronic parts and automobile parts. There is.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a nanocomposite polyamide resin in which thermal conductivity is improved without impairing fluidity by dispersing layered fillers such as layered silicates to the molecular level. As a matrix resin and using spherical alumina in a highly filled state, it was found that a heat conductive resin application that is electrically insulating and excellent in heat conductivity can be obtained, and the present invention was mistaken.

  If the amount of layered silicate added is 2% by weight or less, the thermal conductivity of the matrix resin is insufficient to improve, and if it is 5% by weight or more, the fluidity of the nanocomposite resin itself is hindered and high filling with alumina cannot be performed. Preferably, 4 to 5% by weight is optimal.

(1) As a matrix resin, a highly heat-conducting inorganic particulate filler was added to the nanocomposite polyamide resin, thereby providing a molding resin that was electrically insulating and excellent in thermal conductivity.
(2) In the above (1), by forming a high blend of alumina as the thermally conductive inorganic particulate filler, a molding resin that is electrically insulating and excellent in thermal conductivity was obtained.
(3) The layered filler used in the nanocomposite polyamide resin in the above (1) and (2) is a layered silicate, and the silicate layer is uniformly dispersed at a molecular level. It became a molding resin with excellent insulation and thermal conductivity.
(4) By using a nanocomposite polyamide resin in which 4 to 5% by weight of layered silicate is blended in (1) to (3) above, it becomes a molding resin that is electrically insulating and excellent in thermal conductivity. It was.
(5) In the above (1) to (4), 5-15% by weight of nanocomposite polyamide resin and 85-95% by weight of alumina are blended, so that it is electrically insulating and has excellent thermal conductivity. It became resin.
(6) In the above (1) to (5), 40 to 70% by weight of the nanocomposite polyamide resin and 30 to 60% by weight of the polyphenylene sulfide resin are blended as the matrix resin, so that it is electrically insulating and thermally conductive. It became an excellent molding resin.

  The nanocomposite polyamide resin used in the present invention is commercially available in which a layered silicate is dispersed at the molecular level during the polyamide polymerization step. For example, nanocomposite nylon (trade name; NANOCON) manufactured by Unitika Co., Ltd. has no change in fluidity, high strength and excellent heat resistance compared to unblended 6 nylon.

  Here, being uniformly dispersed at the molecular level means that when the layered silicate is dispersed in the polyamide resin matrix, each of them maintains an average layered distance of 20 A or more. Here, the lamellar distance refers to the distance between the centers of gravity of the silicate layers of the lamellar silicate, and uniformly dispersed means that each of the silicate layers is a multilayer having an average overlap of 5 layers or less. In a state where an object is parallel or random, or in a state where parallel and random are mixed, 50% or more, preferably 70% or more, is dispersed without forming a lump. Specifically, it can be confirmed by observing a transmission electron micrograph or evaluating variation in tensile elongation.

  For the alumina used in the present invention, a combination of spherical particles having different particle diameters is effective for close-packed high packing. The addition amount is desirably 85 to 95% by weight. If the amount is 95% by weight or more, the fluidity of the resin is poor, and if it is 85% by weight or less, the effect of heat conduction is small.

The resin used in the present invention can be used in combination with a conventionally known resin for the purpose of improving the physical properties of the nanocomposite polyamide resin without impairing the thermal conductivity. Specifically, for example, polyphenylene sulfide resin, polyether resin, polyester resin, polyimide resin, polycarbonate carbonate tallow, urethane resin, epoxy resin, phenol resin, silicone resin, fluorine resin, olefin resin, Examples include styrene resins, vinyl acetate resins, acrylic resins, natural or synthetic rubber resins, and the like.
Furthermore, fluidity | liquidity and heat resistance can be provided, without impairing the thermal conductivity of a resin composition by mix | blending polyphenylene sulfide resin with nanocomposite polyamide resin as optimal mixing | blending.

  The layered silicate used in the present invention is not limited to mica, and includes montmorillonite and vermiculite.

  The thermally conductive inorganic particulate filler used in the present invention is not limited to alumina, and ceramic particles such as magnesium oxide, silica, zinc oxide, boron nitride, silicon carbide, and silicon nitride can be used.

  The nanocomposite nylon 6 and spherical alumina were melt-kneaded using a screw type twin screw extruder and pelletized under the conditions of a cylinder temperature of 230 ° C. and a screw rotation speed of 50 rpm. The resin composition obtained here was injection molded into a test piece, and the thermal conductivity and electric conductivity were measured. Regarding the measurement of thermal conductivity, in accordance with ASTM E1530, a test piece of φ50 mm × t3 mm was measured at 23 ° C. using an Anita Unithermo 2021 type tester.

  As nanocomposite polyamide resin, nanocomposite 6 nylon (trade name; NANOCO) M1030DH (containing 4% by weight of synthetic mica) manufactured by Unitika Ltd. was weighed to 15% by weight and 85% by weight of spherical alumina was dry blended. Were kneaded and pelletized by the method described above, and the physical properties were evaluated.

  As nanocomposite polyamide resin, we measured 10% by weight of nanocomposite 6 nylon (trade name: NANOCO) M1030DH (with 4% by weight of synthetic mica) manufactured by Unitika Ltd. and 90% by weight of spherical alumina, followed by dry blending. The properties were evaluated by kneading and pelletizing.

  As nanocomposite polyamide resin, nanocomposite 6 nylon (trade name: NANOCO) M1030DH (4% by weight of synthetic mica) manufactured by Unitika Ltd. was weighed to 5% by weight and 95% by weight of spherical alumina were dry blended. The properties were evaluated by kneading and pelletizing.

[Comparative Example 1]
As Comparative Example 1, 85 wt% of spherical alumina was weighed in 15 wt% of 6 nylon resin (trade name; Unitika nylon 6A1030JR) manufactured by Unitika Ltd., and the physical properties were evaluated by kneading and pelletizing in the same manner as in the examples.

[Comparative Example 2]
As Comparative Example 2, 90 wt% of spherical alumina was weighed into 10 wt% of 6 nylon resin (trade name; Unitika nylon 6A1030JR) manufactured by Unitika Ltd., and then kneaded and pelletized in the same manner as in the Examples to evaluate physical properties.

[Comparative Example 3]
As Comparative Example 3, 95% by weight of spherical alumina was weighed in 5% by weight of 6 nylon resin (trade name; Unitika Nylon 6A1030JR) manufactured by Unitika Co., Ltd., and then kneaded and pelletized in the same manner as in Examples to evaluate physical properties.

The results are shown in Table 1. By using the nanocomposite polyamide resin, the thermal conductivity of the matrix itself is improved, and the layered silicate fine fibers dispersed at the molecular level are linked to the heat transfer of the alumina particles. In order to exert a synergistic effect as a role, it can be seen that the thermal conductivity is dramatically improved as the alumina filling amount increases.

The application of the molding resin obtained by the present invention having excellent electrical insulation and thermal conductivity is used for resin parts that require heat dissipation and electrical insulation, such as electrical / electronic parts and automobile parts.
For example, it is particularly suitable for electrical equipment parts that have high heat generation and require electrical insulation, such as semiconductor elements, resistors, and motors, and can be applied to many heat radiation parts such as automobiles, home appliances, lighting equipment, and office machines.

Claims (3)

The alumina nanocomposite polyamide resin as the matrix resin as a thermally conductive inorganic particulate filler Ri greens and high loading,
The layered filler used in the nanocomposite polyamide resin is a layered silicate, and the silicate layer is uniformly dispersed at the molecular level,
A molding resin excellent in electrical insulation and thermal conductivity, comprising 5 to 15% by weight of nanocomposite polyamide resin and 85 to 95% by weight of alumina .   The molding resin having excellent electrical insulation and thermal conductivity according to claim 1, wherein a nanocomposite polyamide resin containing 4 to 5% by weight of layered silicate is used.   The molding resin according to claim 1 or 2, comprising 40 to 70% by weight of a nanocomposite polyamide resin and 30 to 60% by weight of a polyphenylene sulfide resin as a matrix resin.