JP2007302831A - Thermoplastic resin composition and molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molded product good in thermal conductivity, lightweightness and low electrical conductivity, and to obtain a resin composition suitable for obtaining the above molded product. <P>SOLUTION: The thermoplastic resin composition is obtained by melt-kneading together 20-85 mass% of (A) a thermoplastic resin including polybutylene terephthalate, 1-40 mass% of (B) a metal including tin, 5-40 mass% of (C) graphite and 5-50 mass% of (D) a fibrous filler including PAN-based carbon fiber. The resin molded product 1.7 or less in specific gravity, 4 W/K×m or higher in thermal conductivity, 2.5 W/K×m or higher in specific thermal conductivity and 1,000Ω or higher in surface resistivity is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin composition having excellent thermal conductivity used in the electrical and electronic field.

Polyester resins typified by polybutylene terephthalate are excellent in various physical properties, and are therefore used in a wide range of applications such as molded articles, packaging films, and fibers. Among these, polyester resins are particularly excellent in heat resistance, rigidity, impact resistance, and the like, and therefore have promising uses in the fields of automobiles and home appliances, and are widely used in these applications.
In these fields of automobiles and home appliances, in addition to miniaturization and weight reduction, fine electronic control is being promoted due to various demands. With this, heat storage of electronic components affects the life of products. There is a problem to give.

In order to solve this heat storage problem, heat dissipation technology using metal heat sinks using metal substrates such as aluminum and copper is currently the mainstream technology, but there are problems that there are many restrictions in terms of miniaturization, weight reduction, and design. is there. Therefore, it is conceivable to use a resin that is easy to reduce in size and weight and has a high degree of design freedom. However, since the resin generally has low heat dissipation, it cannot be used as it is for these members.
Therefore, a resin material excellent in thermal conductivity has been proposed as a resin material having heat dissipation (see, for example, Patent Document 1).

In Patent Document 1, a metal material such as lead-free solder and copper powder is added to a thermoplastic resin such as a polyolefin-based elastomer to obtain a thermoplastic resin having high thermal conductivity. However, although the thermal conductivity is improved by adding a metal material, on the other hand, when only the metal material is used as a heat conductive component, the specific gravity is increased, which is disadvantageous for weight reduction. In addition, when a metal material is used as a heat conductive component, not only the heat conductivity but also the conductivity becomes high, so that there is a problem that it cannot be directly attached to the electronic substrate. As described above, none of the conventional techniques satisfies thermal conductivity, light weight, and low conductivity.
JP 2002-3829 A

  An object of the present invention is to provide a resin molded article having good thermal conductivity, light weight, and low conductivity, and to provide a thermoplastic resin composition suitable for such a molded article.

  The present invention relates to a thermoplastic resin (A) 20 to 85% by mass containing polybutylene terephthalate, 1 to 40% by mass of a metal (B) containing tin, 5 to 40% by mass of graphite (C), and a PAN system. The present invention relates to a thermoplastic resin composition obtained by melt-kneading 5 to 50% by mass of a fibrous filler (D) containing carbon fiber, having a specific gravity of 1.7 or less and a thermal conductivity of 4 W / K · m or more. And a specific heat conductivity of 2.5 W / K · m or more and a surface resistance value of 1000 Ω or more.

  Since the thermoplastic resin composition of the present invention contains a metal (B) containing tin and a fibrous filler (D), the specific gravity, thermal conductivity, and specific heat conductivity can be obtained by molding this. A good molded product can be obtained. Further, by containing PAN-based carbon fiber as the fibrous filler (D), the surface resistance value of the molded product is increased, and it becomes a semi-conductive or insulating, lightweight molded product with a low specific gravity. Therefore, the molded product of the present invention is suitable for a heat dissipation member.

  The thermoplastic resin composition of the present invention comprises a thermoplastic resin (A) 20 to 85% by mass containing polybutylene terephthalate, a metal (B) 1 to 40% by mass containing tin, and a graphite (C) 5 to 40% by mass. %, And 5 to 50% by mass of a fibrous filler (D) containing PAN-based carbon fiber.

Content of a thermoplastic resin (A) is 20-85 mass% in the thermoplastic resin composition whole quantity.
When the content of the component (A) is 20% by mass or more, the mechanical strength tends to be sufficient, and when the content of the component (A) is 85% by mass or less, sufficient heat dissipation is obtained. It tends to be obtained.
(A) 25 mass% or more is preferable and, as for the lower limit of content of a component, 30 mass% or more is especially preferable. Moreover, 75 mass% or less is preferable and, as for the upper limit of content of (A) component, 65 mass% or less is especially preferable.

  The thermoplastic resin (A) contains polybutylene terephthalate. Although content in particular of polybutylene terephthalate is not restrict | limited, The range of 10-85 mass% is preferable in the thermoplastic resin composition whole quantity. When the content of polybutylene terephthalate is 10% by mass or more, moldability tends to be good, and when it is 85% by mass or less, heat dissipation tends to be sufficient. The lower limit of the content of polybutylene terephthalate is more preferably 13% by mass or more, and particularly preferably 15% by mass or more. Further, the lower limit of the content is more preferably 75% by mass or less, and particularly preferably 65% by mass or less.

The thermoplastic resin (A) may contain other thermoplastic resins in addition to polybutylene terephthalate.
The other thermoplastic resin is not particularly limited, and examples thereof include aromatic resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, and polyester resins such as polyether ester type or polyester ester type polyester elastomer.

  The intrinsic viscosity ([η]) of the polyester resin is not particularly limited, but the intrinsic viscosity measured with an equimolar mixture of 1,1,2,2-tetrachloroethane and phenol in an atmosphere at 25 ° C. is 0.5. -2.0 dl / g is preferred. When the intrinsic viscosity is 0.5 dl / g or more, a molded product having sufficient strength tends to be obtained, and when it is 2.0 dl / g or less, the fluidity tends to be good and the filling property tends to be sufficient. is there. The lower limit of the intrinsic viscosity is more preferably 0.7 dl / g or more, and particularly preferably 0.8 dl / g or more. The upper limit is more preferably 1.7 dl / g or less, and particularly preferably 1.5 dl / g or less.

  The production method of the polyester resin is not particularly limited, and can be produced by a commonly used direct esterification method or transesterification esterification reaction, followed by a polycondensation reaction. It is also possible to increase the molecular weight.

In addition to these polyester resins, for example, polymers containing rubber components such as ABS resins, polyolefin-based elastomers, and polycarbonates can be used.
Among these, a rubber component-containing polymer such as an ABS resin is preferable from the viewpoint of warpage suppression, and a polyolefin elastomer is preferable from the viewpoint of hydrolysis resistance, from the viewpoint of warpage suppression and impact resistance. Is preferably polycarbonate.

Next, the metal (B) containing tin will be described.
Content of the metal (B) containing a tin is 1-40 mass% in the thermoplastic resin composition whole quantity.
When the content of the component (B) is 1% by mass or more, the thermal conductivity tends to be good, and when the content of the component (B) is 40% by mass or less, the specific gravity is 1. 7 or less.
(B) 2 mass% or more is preferable and, as for the lower limit of content of a component, 3 mass% or more is especially preferable. Further, the upper limit of the content of the component (B) is preferably 37% by mass or less, and particularly preferably 35% by mass or less.

  Specific examples of the metal (B) containing tin (Sn) include, for example, Sn / Ag, Sn / Bi, Sn / Cu, Sn / Zn, Sn / Ag / Cu, Sn / Ag / Bi / Cu, Pb Examples thereof include so-called solder alloys such as / Sn, Pb / Sn / Ag, and Pb / Sn / Bi. Moreover, it can also be used as a mixture with metals, such as Al, Cu, Ni, and it can anticipate improving heat dissipation and a dispersibility by this.

Content of graphite (C) is 5-40 mass% in the thermoplastic resin composition whole quantity.
When the content of the component (C) is 5% by mass or more, the thermal conductivity tends to be good, and when the content of the component (C) is 40% by mass or less, the flow during melting Tend to be good.
(C) As for the lower limit of content of a component, 10 mass% or more is more preferable, and 15 mass% or more is especially preferable. Further, the upper limit value of the content of the component (C) is more preferably 37% by mass or less, and particularly preferably 35% by mass or less.

Content of the fibrous filler (D) containing a PAN-type carbon fiber is 5-50 mass% in the thermoplastic resin composition whole quantity.
When the content of the component (D) is 5% by mass or more, the thermal conductivity tends to be good and the specific gravity tends to be low, and when the content of the component (D) is 50% by mass or less, melting There is a tendency that the fluidity of the time becomes good.
(D) As for the lower limit of content of a component, 7 mass% or more is more preferable, and 10 mass% or more is especially preferable. Further, the upper limit value of the content of the component (D) is more preferably 40% by mass or less, and particularly preferably 35% by mass or less.

(D) A component contains a PAN-type carbon fiber. By using a metal containing tin and a fibrous filler in combination, a resin composition having a small specific gravity and a high thermal conductivity can be obtained.
Carbon fibers include PAN-based, pitch-based, or vapor-grown carbon fibers, but PAN-based carbon fibers are essential to keep conductivity low. Further, examples of the PAN-based carbon fiber include long fiber type and short fiber type chopped strands, milled fibers, and the like, but chopped strands or milled fibers are preferable in order to keep conductivity low.

The elastic modulus of the PAN-based carbon fiber is not particularly limited, but is preferably 195 to 450 GPa from the viewpoint of suppressing fiber breakage during molding. The lower limit value of the elastic modulus of the PAN-based carbon fiber is more preferably 215 GPa or more, and the upper limit value is more preferably 390 GPa or less.
The diameter of the PAN-based carbon fiber is not particularly limited, but is preferably 1 to 10 μm.

The surface treatment of the PAN-based carbon fiber is not particularly limited, but it is preferable to perform a treatment such as a surface oxidation treatment in order to suppress the mechanical strength and conductivity of the resin composition.
Examples of the oxidation treatment method include surface oxidation by energization treatment, and oxidation treatment in an oxidizing gas atmosphere such as ozone, and energization treatment is preferably used.
Further, epoxy type, polyamide type, urethane type, polyester type, and the like can be used as the sizing agent. It is preferable to use an epoxy type as a primary sizing agent and a polyamide type or urethane type sizing agent as a secondary sizing agent. More preferably, the system is used.

  The form of the PAN-based carbon fiber is not particularly limited, but is used in the form of a strand composed of a bundle of thousands to hundreds of thousands of carbon fibers. Regarding the strand form, it is possible to use a directly introduced roving method or a chopped strand cut to a predetermined length, but the chopped strand is preferable in that the conductivity can be kept low.

The content of the PAN-based carbon fiber is not particularly limited, but is preferably 1 to 20% by mass in the total amount of the thermoplastic resin composition. When the content of the PAN-based carbon fiber is 1% by mass or more, the specific gravity tends to be low, and when the content is 20% by mass or less, the conductivity tends to be low. The lower limit of the content of the PAN-based carbon fiber is more preferably 2% by mass or more, and particularly preferably 3% by mass or more. Moreover, the upper limit of this content is more preferably 17% by mass or less, and particularly preferably 15% by mass or less.
Although it does not specifically limit as fibrous fillers other than PAN type carbon fiber, Inorganic fibers, such as glass fiber and a wollastonite, can be mentioned.

About the manufacturing method of the thermoplastic resin composition of this invention, it does not restrict | limit in particular, It can manufacture with the equipment and method generally used as a manufacturing method of the conventional thermoplastic resin composition. Among them, the melt kneading method is preferable. The apparatus used for melt kneading is not particularly limited, and examples thereof include an extruder, a Banbury mixer, a roller, and a kneader. As the extruder, there are a single screw extruder and a twin screw extruder, but a twin screw extruder is preferable in order to perform kneading in a short time.
The method for cooling the extruded strand is not particularly limited, and examples include cooling by water cooling using a water tank, air cooling using a screen conveyor, water cooling, or cooling by air cooling and water cooling.

Next, the molded product of the present invention will be described.
The specific gravity of the molded product of the present invention is 1.7 or less.
When the molded product of the present invention is used for a heat radiating member as a metal substitute, the specific gravity needs to be 1.7 or less.
The lower limit of the specific gravity of the molded product is not particularly limited, but is preferably 1.5 or more.

The thermal conductivity of the molded article of the present invention is 4 W / K · m or more.
When the thermal conductivity of the molded product is 4 W / K · m or more, the thermal conductivity tends to be good. The upper limit of the thermal conductivity is not particularly limited, but is preferably 20 W / K · m or less.
The specific heat conductivity of the molded article of the present invention is 2.5 W / K · m or more. In the present invention, the specific heat conductivity is a value obtained by dividing the heat conductivity by the specific gravity.
When the specific heat conductivity of the molded product is 2.5 W / K · m or more, the heat dissipation tends to be good and the light weight tends to be excellent. The upper limit of the specific heat conductivity is not particularly limited, but is preferably 10 W / K · m or less.

The surface resistance value of the molded article of the present invention is 1000Ω or more.
When the surface resistance value of the molded product is 1000Ω or more, it becomes semiconductive and the conductivity tends to be suppressed. The surface resistance value of the molded product is preferably 10,000 Ω or more, particularly preferably 100,000 Ω or more. The upper limit of the surface resistance value is not particularly limited, but is preferably 10 billion Ω or less.

The molded article of the present invention can be obtained by molding the thermoplastic resin composition of the present invention.
The method for molding the thermoplastic resin composition is not particularly limited. Examples include injection molding, extrusion molding, rod-shaped, hollow, and sheet-shaped molding, vacuum molding, blow molding, and the like. A resin molded product can be obtained by these molding methods.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example.
(1) Evaluation method of thermoplastic resin composition and molded product The evaluation of the thermoplastic resin composition and the molded product was measured according to the following method.

(1-1) Thermal conductivity A stationary heat flow meter manufactured by DYNATECH R & D (model number TCHM-DV) was used. In the measurement, in order to accurately measure the temperature difference between the upper and lower surfaces of the sample, a copper-constantan thermocouple was embedded in the upper and lower surfaces of the sample by hot pressing. By using a hot press, the flatness of the sample can be improved and the adhesion between the sample and the thermocouple can be increased. Further, in order to stabilize the heat flow, the measurement was performed after maintaining the predetermined temperature for 1 hour. Tables 1 and 2 show the measurement results of thermal conductivity.

(1-2) Specific gravity The resin composition was injection molded, and the specific gravity was determined by an underwater substitution method (JIS K7112).
(1-3) Specific heat conductivity The heat conductivity obtained in (1-1) was divided by the specific gravity obtained in (1-2) to obtain specific heat conductivity.
(1-4) Surface resistance value About the ISO dumbbell type test piece, the surface resistance value between two points was measured using a probe type terminal. (Measures the center of the dumbbell along the flow direction using an Advantest high resistivity meter)

(2) Raw material used (2-1) Thermoplastic resin (A)
・ PBT Novaduran 5008 (Mitsubishi Engineering Plastics polybutylene terephthalate, intrinsic viscosity [η] = 0.9 dl / g)
PET GM502S (Mitsubishi Chemical Polyethylene terephthalate, intrinsic viscosity [η] = 0.8 dl / g)
・ Polyester elastomer Perprene GP300 (polyester-polyether block copolymer manufactured by Toyobo Co., Ltd.)
・ Rubber component-containing polymer UMG-AXS resin R-40 (grafted rubber polymer manufactured by UMG ABS)

(2-2) Tin-containing metal (B)
Sn-Cu metal powder (average specific gravity: 7.96) Mixture of Sn-Cu alloy powder (average particle size: 15.5 μm) and copper powder (average particle size: 62 μm) (2-3) Graphite (C) Chuetsu BBC-150S manufactured by Graphite Industries Co., Ltd.

(2-4) Fibrous filler (D)
-PAN-based carbon fiber chop (TR06UB4E manufactured by Mitsubishi Rayon Co., Ltd. Chopped carbon fiber. Fiber diameter 7 μm, primary sizing agent, epoxy-based, secondary sizing agent polyurethane-based, tensile elastic modulus 235 GPa, fiber length 6 mm, convergence number 12,000)
・ PAN-based carbon fiber milled (manufactured by TC Techno Co., Ltd. Milled carbon fiber Milled fiber MME Fiber diameter 7μm Average fiber length 80μm)
・ Glass fiber (ECS03 T-187 manufactured by Nippon Electric Glass Co., Ltd., fiber diameter 13μm, sizing agent aminosilane, fiber length 3mm)
・ Pitch-based carbon fiber chops (K223HG chopped carbon fiber, fiber diameter 10 μm, fiber length 6 mm, manufactured by Mitsubishi Chemical)

(2-6) Others ・ Micron White # 5000A (Talc manufactured by Hayashi Kasei)
-ADK STAB AO-60 (Asahi Denka Kogyo Co., Ltd. hindered phenol antioxidant)
・ ADK STAB PEP-36 (Asahi Denka Kogyo thioether antioxidant)
・ LICOWAX-OP (Clariant Japan's mold release agent, partially saponified ester of montanic acid)

Examples 1-4 and Comparative Examples 1-4
Using a twin screw extruder (PCM-45 manufactured by Ikegai Seisakusho), the components shown in Table 1 and Table 2 were supplied from a resin feeder and melt-kneaded at a resin temperature of 280 ° C. to obtain resin composition pellets. . In addition, it depressurizes from the vent port provided in the middle of the extruder here, and the water | moisture content is removed.
Next, the pellets were dried with hot air at 150 ° C. for 2 hours, and using an injection molding machine (Japan Steel Works (JSW) 75T injection molding machine J75SSII), temperature conditions of a resin temperature of 260 ° C. and a mold temperature of 80 ° C. Various test pieces were molded. The evaluation results of the molded products are shown in Tables 1 and 2.

  The resin composition of the present invention can be used in the electric and electronic fields where thermal conductivity, light weight and low conductivity are required, and among them, it can be suitably used as a heat radiating member such as a heat sink or a fan.

Claims (2)

  20 to 85% by mass of thermoplastic resin (A) containing polybutylene terephthalate, 1 to 40% by mass of metal (B) containing tin, 5 to 40% by mass of graphite (C), and PAN-based carbon fiber A thermoplastic resin composition obtained by melt-kneading 5 to 50% by mass of a fibrous filler (D).   A molded article having a specific gravity of 1.7 or less, a thermal conductivity of 4 W / K · m or more, a specific thermal conductivity of 2.5 W / K · m or more, and a surface resistance of 1000 Ω or more.