JP2022186199A - Thermally conductive resin composition and molding thereof - Google Patents

Abstract

To provide a resin composition that can produce a molding having excellent fogging resistance while a thermal conductivity of 2 W/(m K) or more in a flow direction.SOLUTION: A thermally conductive resin composition contains a thermoplastic resin (A) and flaky graphite with an average particle size of 100-500 μm (B). The mass ratio between the thermoplastic resin (A) and the flaky graphite (B) is 38/62-85/15. After a fogging test at 125°C for 200 hours, a glass plate has a haze value of 8 or less. A molding of the thermally conductive resin composition has a thermal conductivity of 2 W/(m K) or more in a flow direction.SELECTED DRAWING: Figure 1

Description

INDUSTRIAL APPLICABILITY The present invention is capable of producing a molded article containing a thermoplastic resin and flake graphite and having a heat conductivity of 2 W/(m·K) or more in the direction of flow and having excellent design properties and anti-fogging properties. The present invention relates to a thermally conductive resin composition that can be obtained and a molded article made from the same.

In recent years, the amount of heat generated has increased due to the high performance of parts and products. Therefore, heat countermeasures for effectively dissipating the generated heat to the outside have become a very important issue, and calls for improving the heat dissipation properties of the resin molding materials (for example, resin compositions) that are the constituent materials have become louder. is coming. For example, it is necessary for LEDs to dissipate heat efficiently in order to extend their life, and it is also important that the lenses do not fog up when the lamp is lit for a long period of time. Therefore, the member used is also required to have good anti-fogging properties. Considering the amount of heat dissipation that leads to a longer life of the LED, the thermal conductivity in the flow direction is 2 W/(m・K) is required. Therefore, there is a demand for a material having a thermal conductivity of 2 W/(m·K) or more in the direction of flow of the molded body and having good anti-fogging properties.

Until now, it has been known that a resin composition having a high thermal conductivity can be obtained by highly filling a resin material with a thermally conductive filler having high thermal conductivity (eg, graphite, copper, aluminum, aluminum oxide, etc.). It is A molded article produced using such a resin composition has been studied as a member for producing electric/electronic parts (for example, Patent Documents 1 to 4).

On the other hand, in the field of thermally conductive resin compositions, it is also required to be able to produce molded articles with excellent mechanical strength such as bending strength and bending elastic modulus with good fluidity. It is also required that the molded product be excellent in design.

JP-A-62-100577 JP-A-4-178421 JP-A-5-86246 JP-A-2011-116842

The inventors of the present invention have found that when a resin composition containing a large amount of a thermally conductive filler is produced by a conventional production method, gas extraction during production is insufficient, and the resin composition obtained using the resin composition It has been found that a problem arises in that the anti-fogging property of the formed article is deteriorated. Specifically, in the conventional method, the evacuation of gas during the production of the resin composition is performed by simply evacuating from a vent port provided in the vicinity of the most downstream side in the extrusion direction of the extruder. At this time, if the resin composition contains a large amount of thermally conductive filler, the internal pressure tends to increase, and the molten material tends to overflow from the vent port and/or the vent port tends to be blocked. , it was not possible to draw gas sufficiently. For this reason, it is considered that residual monomer components in the thermoplastic resin, components of decomposition products due to heat, and the like cannot be sufficiently removed from the resin composition, and the fogging resistance of the molded article deteriorates.

The present invention provides a resin composition and a molded article obtained from the resin composition that can produce a molded article having excellent design and anti-fogging properties while having a thermal conductivity in the direction of flow of 2 W/(m·K) or more. intended to provide

The present invention also provides a resin composition capable of producing a molded article having excellent designability, anti-fogging properties, bending properties and molding fluidity while having a thermal conductivity of 2 W/(m·K) or more in the direction of flow. An object of the present invention is to provide an article and a molded article obtained therefrom.

In this specification, thermal conductivity refers to the property of easily conducting heat in a molded article produced using a thermally conductive resin composition.
The term "designability" refers to the characteristics that the surface of a molded article produced using a thermally conductive resin composition has high glossiness and little graininess. The surface glossiness indicates how much light that hits the surface is reflected, and the graininess indicates a so-called glaring feeling.
Anti-fogging property means that a molded article manufactured using a thermally conductive resin composition is resistant to fogging even in a high temperature environment of 100° C. or higher (for example, 125° C.).
The flexural properties are properties in which the flexural strength and flexural modulus of a molded article produced using the thermally conductive resin composition are sufficiently high.
Molding fluidity is a property that allows the resin composition to flow sufficiently when a molded article is produced using the thermally conductive resin composition.

Thermal conductivity, designability and anti-fogging properties are properties possessed by the thermally conductive resin composition of the present invention.
Bending properties and molding fluidity are not properties that the thermally conductive resin composition of the present invention must have, but properties that the thermally conductive resin composition of the present invention usually has or preferably has. is.

As a result of intensive research to solve the above problems, the present inventors have found that a thermoplastic resin and flake graphite with a specific average particle size are compounded at a specific ratio, and gas is drawn by a vacuum pump when compounding. The inventors have found that the above problems can be solved by strengthening the

The gist of the present invention is as follows.
<1> A thermally conductive resin composition containing a thermoplastic resin (A) and flake graphite (B) having an average particle size of 100 to 500 μm,
The mass ratio of the thermoplastic resin (A) and the flake graphite (B) is 38/62 to 85/15,
The glass plate has a haze value of 8 or less after a fogging test at 125 ° C. for 200 hours,
A thermally conductive resin composition, wherein a molded body obtained by molding the thermally conductive resin composition has a thermal conductivity in the flow direction of 2 W/(m·K) or more.
<2> The thermally conductive resin composition further contains a non-thermally conductive fibrous reinforcing material (C), and the total of the thermoplastic resin (A) and the flake graphite (B) and the non-thermally conductive The thermally conductive resin composition according to <1>, wherein the mass ratio to the elastic fibrous reinforcing material (C) is 100/0 to 50/50.
<3> The thermally conductive resin composition according to <1>, wherein the non-thermally conductive fibrous reinforcing material (C) is glass fiber.
<4> The thermally conductive resin composition according to any one of <1> to <3>, wherein the thermoplastic resin (A) is polyamide.
<5> The thermoplastic resin (A) is composed of a crystalline polyamide and an amorphous polyamide, and the mass ratio of the crystalline polyamide and the amorphous polyamide is 100/0 to 40/60. The thermally conductive resin composition according to any one of 1> to <4>.
<6> A molded article made of the thermally conductive resin composition according to any one of <1> to <5>.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a resin composition capable of producing a molded article having excellent design and anti-fogging properties while having a thermal conductivity of 2 W/(m·K) or more in the direction of flow, and a resin composition obtained thereby. Molded bodies can be provided.

1 shows a schematic cross-sectional view of an extruder for producing the resin composition of the present invention. FIG. BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram for demonstrating the measuring method of the haze value which prescribes|regulates the resin composition of this invention is shown. FIG. 2 shows a schematic diagram of an air collection bottle used in the method for measuring the haze value that defines the resin composition of the present invention.

[Thermal conductive resin composition]
The thermally conductive resin composition of the present invention contains a thermoplastic resin (A) and flake graphite (B).

The thermoplastic resin (A) used in the present invention is not particularly limited, but examples include olefin resins such as polyethylene, polypropylene, ethylene-α-olefin copolymers (e.g., ethylene-propylene copolymers, etc.); polymethylpentene; Polyvinyl chloride; Polyvinylidene chloride; Polyvinyl acetate; Ethylene-vinyl acetate copolymer; Polyvinyl alcohol; Polyvinyl acetal; , polyester resins such as polylactic acid; polystyrene; polyacrylonitrile; styrene-acrylonitrile copolymer; ABS resin; polyphenylene ether (PPE); modified PPE; polymethacrylic acid ester such as methyl methacrylate; polyacrylic acid; polycarbonate; polyarylate; polyphenylene sulfide; polysulfone; Among these, amide bond-containing polymers, particularly polyamide resins, are preferable because they are excellent in moldability and tend to exhibit thermal conductivity when flake graphite (B) is blended.

Polyamide resins used in the present invention are homopolyamides or copolyamides having amide bonds, or mixtures thereof. Homopolyamides and copolyamides having amide bonds can be obtained by polymerizing lactams, aminocarboxylic acids, diamines, dicarboxylic acids and the like. Lactams, aminocarboxylic acids, diamines, and dicarboxylic acids that constitute homopolyamides and copolyamides include lactams, aminocarboxylic acids, diamines, and dicarboxylic acids that can constitute crystalline polyamides and amorphous polyamides, respectively. .

The crystallinity (or amorphous) of the polyamide resin is not particularly limited, and the polyamide resin is, for example, a crystalline polyamide (A-1-1) alone or a crystalline polyamide (A-1-1) and an amorphous polyamide Any mixture of (A-1-2) may be used.

The crystalline polyamide (A-1-1) has a heat of fusion value of 1 cal/g or more measured at a heating rate of 16° C./min under a nitrogen atmosphere using a differential scanning calorimeter (DSC). It means polyamide resin.
The amorphous polyamide (A-1-2) has a heat of fusion value of less than 1 cal/g measured at a heating rate of 16°C/min under a nitrogen atmosphere using a differential scanning calorimeter (DSC). means a certain polyamide resin.

Examples of the crystalline polyamide (A-1-1) include polytetramethylene isophthalamide (polyamide 4I), polytetramethylene terephthalamide (polyamide 4T), polycapramide (polyamide 6), polytetramethylene adipamide (polyamide 46 ), polyhexamethylene adipamide (polyamide 66), polycapramide/polyhexamethylene adipamide copolymer (polyamide 6/66), polyundecamide (polyamide 11), polycapramide/polyundecamide copolymer (polyamide 6/11), polydodedecamide (polyamide 12), polycapramide/polydodedecamide copolymer (polyamide 6/12), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecamethylene adipamide (polyamide 116) , polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalamide (polyamide 6T), polycapramide/polytetramethylene terephthalamide copolymer (polyamide 6/4T), polycapramide/polytetramethylene isophthalamide copolymer (polyamide 6/4I) , polyhexamethylene adipamide/polytetramethylene terephthalamide copolymer (polyamide 66/4T), polyhexamethylene adipamide/polytetramethylene isophthalamide copolymer (polyamide 66/4I), polyhexamethylene terephthalamide/polyhexamethylene Isophthalamide Copolymer (Polyamide 6T/6I), Polycapramide/Polyhexamethylene Terephthalamide Copolymer (Polyamide 6/6T), Polycapramide/Polyhexamethylene Isophthalamide Copolymer (Polyamide 6/6I), Polyhexamethylene Adipamide/Polyhexamethylene Terephthalamide Copolymer (Polyamide 66/6T), Polyhexamethyleneadipamide/Polyhexamethyleneisophthalamide Copolymer (Polyamide 66/6I), Polytrimethylhexamethyleneterephthalamide (Polyamide TMDT), Polybis(4-aminocyclohexyl)methandodeca amide (polyamide PACM12), polybis(3-methyl-4-aminocyclohexyl)methandodedecamide (polyamide dimethyl PACM12), polymetaxylylene adipamide (polyamide MXD6), polyoctamethylene terephthalamide ( polyamide 8T), polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), polyundecamethylene terephthalamide (polyamide 11T) and mixtures thereof. Among them, polyamide 6 and/or polyamide 66 are more preferable from the viewpoint of further improving thermal conductivity, design and anti-fogging properties, as well as improving bending properties and molding fluidity. The crystalline polyamide resin may be used alone or in combination among the above.

Examples of the amorphous polyamide (A-1-2) include isophthalic acid/terephthalic acid/1,6-hexanediamine/bis(3-methyl-4-aminocyclohexyl)methane copolymer, terephthalic acid/2, 2,4-trimethyl-1,6-hexanediamine/2,4,4-trimethyl-1,6-hexanediamine copolymer, isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-lauro Lactam copolymer, isophthalic acid/terephthalic acid/1,6-hexanediamine copolymer, isophthalic acid/2,2,4-trimethyl-1,6-hexanediamine/2,4,4-trimethyl-1,6 -Hexanediamine copolymer, isophthalic acid/terephthalic acid/2,2,4-trimethyl-1,6-hexanediamine/2,4,4-trimethyl-1,6-hexanediamine copolymer, isophthalic acid/bis Examples thereof include (3-methyl-4-aminocyclohexyl)methane/ω-laurolactam copolymers and copolymers of isophthalic acid/terephthalic acid/other diamine components. Among them, isophthalic acid/terephthalic acid/1,6-hexanediamine/bis(3-methyl-4-amino cyclohexyl)methane copolymer, terephthalic acid/2,2,4-trimethyl-1,6-hexanediamine/2,4,4-trimethyl-1,6-hexanediamine copolymer, isophthalic acid/terephthalic acid/1 ,6-hexanediamine/bis(3-methyl-4-aminocyclohexyl)methane copolymer and terephthalic acid/2,2,4-trimethyl-1,6-hexanediamine/2,4,4-trimethyl-1, Mixtures with 6-hexanediamine copolymers, isophthalic acid/terephthalic acid/1,6-hexanediamine copolymers are preferred, isophthalic acid/terephthalic acid/1,6-hexanediamine/bis(3-methyl-4- Aminocyclohexyl)methane copolymer and isophthalic acid/terephthalic acid/1,6-hexanediamine copolymer are more preferred. The amorphous polyamide resin may be used alone or in combination among the above.

By using the crystalline polyamide (A-1-1) and the amorphous polyamide (A-1-2) together, further improvement in fogging resistance can be achieved, for example, the haze value after the fogging test can be further improved. It is possible to make it smaller.

The mass ratio of the crystalline polyamide (A-1-1) and the amorphous polyamide (A-1-2) is not particularly limited, further improving thermal conductivity, design and fogging resistance, bending properties and molding flow From the viewpoint of improving the properties of be. By setting the ratio of the crystalline polyamide (A-1-1) and the amorphous polyamide (A-1-2) to the above ratio, the fogging resistance is particularly improved, and the mechanical properties (especially bending properties) are maintained. It is possible.

The relative viscosity of the thermoplastic resin (A) (especially polyamide resin) is not particularly limited, but from the viewpoint of improving mechanical properties (especially bending properties) and heat resistance, 96% by mass concentrated sulfuric acid is used as a solvent and the temperature is 25 The relative viscosity measured at a concentration of 1 g/dL at °C is preferably 1.6 or more (especially 1.85 or more). The relative viscosity is usually 3.5 or less, especially 3.2 or less.

The thermoplastic resin composition used in the present invention must contain flake graphite (B) together with the thermoplastic resin (A). The average particle diameter of flake graphite (B) is the average value of the maximum length of arbitrary 100 flake graphite (B) based on microscopic observation.

In order to form a compact having uniform mechanical properties and thermal conductivity with good workability without causing agglomeration due to poor dispersion, the flake graphite (B) has an average particle size of flake graphite. The diameter should be between 100 μm and 500 μm, more preferably between 110 μm and 300 μm, even more preferably between 120 and 300 μm, and most preferably in the range of greater than 180 μm to 300 μm. If the average particle size of the flake graphite (B) is less than 100 μm, good thermal conductivity cannot be obtained, fluidity is lowered, and surface glossiness is lowered, resulting in poor design. If the average particle size of the flake graphite (B) exceeds 500 μm, no improvement in thermal conductivity is observed, the mechanical properties deteriorate, the graininess becomes stronger, and the design deteriorates.

The scale-like graphite (B) used in the present invention is coated with a silane-based coupling agent or a titanium-based coupling agent in order to improve adhesion to the thermoplastic resin (A) as long as the effects of the present invention are not impaired. may be treated. Silane-based coupling agents include, for example, γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyldimethoxymethyl Aminosilane coupling agents such as silane, and epoxysilane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. A ring agent is mentioned. Titanium-based coupling agents include isopropyltristearoyl titanate, isopropyltridodecylbenzenesulfonyltitanate, tetraisopropylbis(dioctylphosphite) titanate, and the like. These may be used independently and may use 2 or more types together.

In the thermoplastic resin composition used in the present invention, the mass ratio (A/B) between the thermoplastic resin (A) and the flake graphite (B) must be 38/62 to 85/15, From the viewpoint of further improving thermal conductivity, design and anti-fogging properties and improving bending properties and molding fluidity, it is preferably 38/62 to 75/25, more preferably 45/55 to 70/30, even more preferably 48/52 to 65/35. If the amount of flake graphite (B) is too large, the fogging resistance is lowered and the bending properties are lowered. If the amount of flake graphite (B) is too small, sufficient thermal conductivity may not be obtained.

The resin composition used in the present invention may contain a fibrous reinforcing material (C) different from flake graphite. Specifically, the fibrous reinforcing material (C) is a non-thermally conductive fibrous reinforcing material. The fibrous reinforcing material (C) has non-thermal conductivity means that the substance constituting the fibrous reinforcing material (C) has a thermal conductivity of less than 5 W / (m K), especially 4 W / (m K) or less It means having a rate.

Non-thermally conductive fibrous reinforcing materials include, for example, inorganic fibers, organic fibers, or fibers composed of mixtures thereof. Examples of inorganic fibers include glass fibers. Organic fibers include, for example, aramid fibers, high-density polyethylene fibers, and other general organic fibers such as polyamide and polyester. In the present invention, glass fibers are preferable from the viewpoint of more effectively improving the bending properties when blended in the composite resin composition of the thermoplastic resin (A) and the flake graphite (B).

The mass ratio of the total of the thermoplastic resin (A)) and the flake graphite (B) to the fibrous reinforcing material (C) is usually 100/0 to 50/50 parts by mass, and the thermal conductivity, design and resistance From the viewpoint of further improving fogging properties and improving bending properties and molding fluidity, it is preferably 100/0 to 75/25 parts by mass, more preferably 90/10 to 75/25 parts by mass. By setting the content of the fibrous reinforcing agent (C) within the above range, the mechanical strength and impact strength can be efficiently improved without impairing the moldability. The fact that the mass ratio of the sum of the thermoplastic resin (A) and flake graphite (B) to the fibrous reinforcing material (C) is 100/0 means that the fibrous reinforcing material (C) is not contained. In other words, the resin composition of the present invention may or may not contain the fibrous reinforcing material (C). When the resin composition of the present invention contains a fibrous reinforcing material (C), the mass ratio of the sum of the polyamide resin (A) and the flake graphite (B) to the fibrous reinforcing material (C) is 99/1 to 50/50 parts by weight, in particular 98/2 to 75/25 parts by weight.

The glass fibers may be surface-treated with a silane coupling agent, a titanium-based coupling agent, a zirconia-based coupling agent, or the like, in order to improve adhesion and uniform dispersibility with the matrix resin. Glass fibers are usually used in the form of chopped strands. The cross-section of the glass fiber may be round, flat, gourd, cocoon-shaped, elliptical, elliptical, rectangular or similar.

The average fiber length of the glass fibers is preferably 1 to 10 mm, more preferably 1.5 to 6 mm. The fiber diameter of the glass fiber is preferably 4-18 μm, more preferably 7-15 μm. If the fiber cross section is other than round, for example, flat, gourd, cocoon, oval, elliptical, or rectangular, the long side (e.g. maximum length) and short side (e.g. maximum length) of the cross section The ratio (that is, the aspect ratio) to the length in the direction perpendicular to the surface is preferably from 1.5 to 10, more preferably from 2 to 8.

Flame retardants, crystal nucleating agents, compatibilizers, lubricants, mold release agents, antistatic agents, antioxidants, weathering agents, etc. are added to the resin composition used in the present invention as long as they do not impair the effects of the present invention. agents may be added.
Examples of flame retardants include halogen-based flame retardants, inorganic flame retardants such as aluminum hydroxide, magnesium hydroxide, and antimony trioxide, phosphinates and diphosphinates and their polymers, melamine polyphosphate, and melamine cyanurate. , red phosphorus, phosphate esters, condensed phosphate esters, and phosphazene compounds.
Crystal nucleating agents include, for example, sorbitol compounds, benzoic acid and metal salts of its compounds, and metal phosphate ester salts.
Examples of compatibilizers include ionomer compatibilizers, oxazoline compatibilizers, elastomer compatibilizers, reactive compatibilizers, and copolymer compatibilizers.
As the pigment, for example, both organic and inorganic pigments can be used.
Examples of antioxidants include hindered phenol-based, phosphite-based, and thioether-based antioxidants.
The weather resistant agent absorbs and blocks ultraviolet rays to prevent photodegradation of the resin, or traps radicals generated by ultraviolet rays or heat to suppress polymer decomposition. Weather resistant agents include, for example, ultraviolet blockers, light stabilizers, ultraviolet absorbers, and antioxidants.
These additives may be used alone or in combination of two or more. In addition, the method of mixing these additives in the present invention is not particularly limited.

[Method for producing thermally conductive resin composition and molded product]
The thermally conductive resin composition of the present invention is prepared by mixing a thermoplastic resin (A), flake graphite (B), and various additives as necessary with a general extruder, for example, a single screw extruder, two It can be produced by melting and kneading using a screw extruder, roll kneader, or Brabender. After melting and kneading, the melt is usually extruded into strands, cooled and solidified, and then cut with a pelletizer to obtain the thermally conductive resin composition of the present invention in the form of pellets. It is effective to use a static mixer or a dynamic mixer together before melting and kneading. It is preferable to use a twin-screw extruder in order to improve the kneading state.

The extruder 10 has a cylinder 1 and a screw 2 arranged in the cylinder 1, for example as shown in FIG. The material added from the main hopper 3 of the extruder 10 is melted and kneaded while being conveyed inside the cylinder 1 by the rotation of the screw 2 and discharged from the discharge port 4 . The extruder 10 usually further has a side feeder 11 in the middle of the extrusion direction of the extruder 10 . In such extruder 10 , at least thermoplastic resin (A) is usually added from main hopper 3 . The method of adding the flake graphite (B) and the fibrous reinforcing material (C) is not particularly limited, but the flake graphite (B) and the fibrous reinforcing material (C) are each independently added to the hopper (especially the main hopper 3 ) or may be added from the side feeder 11 . In a preferred embodiment from the viewpoint of further improving thermal conductivity, design and fogging resistance and improving bending properties and molding fluidity, flake graphite (B) is fed into the main hopper 3 or the side feeder 11 (more preferably side feeder 11). When the fibrous reinforcing material (C) is added from the feeder 11 ), the fibrous reinforcing material (C) is added from the side feeder 11 .

In the production of the thermally conductive resin composition of the present invention, a side vacuum device is used during melting and kneading using an extruder. A side vacuum device is a side vent device for a twin-screw extruder as shown in Japanese Patent No. 5645480, for example. The side vacuum device is, in particular, a device 12 for drawing a vacuum from the side holes of the extruder 10, as shown in FIG. The side vacuum device 12 more specifically has a cylinder (not shown) and a screw (not shown) located inside the cylinder, the rotation of the screw causing the melt from the extruder 10 to The inside of the extruder 10 can be decompressed while preventing backflow. The screw of the side vacuum device 12 has a screw body (ie, screw shaft) and a blade section (ie, crest) helically formed on the surface of the screw body. In the side vacuum device 12, the tip of the blade portion is in close contact with the inner wall of the cylinder in a cross-sectional view perpendicular to the screw axis. Therefore, the side vacuum device 12 can reduce the pressure inside the extruder 10 while preventing the backflow of the melt from the extruder 10 by reducing the pressure between the blade portions while rotating the screw. It is possible. In the present invention, since the side vacuum device 12 is used for melting and kneading, overflow of the flake graphite (B) and backflow of the melt can be prevented even when the flake graphite (B) is highly filled. While preventing this, the pressure reduction inside the extruder is sufficiently achieved. As a result, the gas in the cylinder 1 of the extruder 10 is sufficiently removed, and the residual monomer component and thermal decomposition product component in the thermoplastic resin (A) can be sufficiently removed from the melt. It is considered that both the durability and the anti-fogging property can be achieved at a sufficiently high level. Instead of using the side vacuum device 12, if a general standard vacuum device without a screw is installed at the vent port 5 and used, the blending amount of flake graphite as in the resin composition of the present invention is reduced. If the amount of gas is large, the vent portion will be clogged and the gas cannot be sucked efficiently. Therefore, the anti-fogging property of the obtained resin composition is deteriorated.

The installation position X ₁₂ (see FIG. 1) of the side vacuum device 12 is usually 0.5×Y to 0, where Y (mm) is the distance in the extrusion direction from the main hopper 3 to the discharge port 4 in the extruder 10. .9×Y, and from the viewpoint of further improving anti-fogging properties, the position is preferably 0.6×Y to 0.85×Y, more preferably 0.65×Y to 0.80×Y. position, more preferably 0.65×Y to 0.75×Y.

When the extruder 10 has the side feeder 11, the installation position of the side vacuum device 12 is usually downstream of the installation position of the side feeder 11 in the extrusion direction.

The installation position X ₁₁ (see FIG. 1) of the side feeder 11 is usually 0.3×Y to 0.3×Y to 0.3×Y, where Y (mm) is the distance in the extrusion direction from the main hopper 3 to the discharge port 4 in the extruder 10 . 7×Y position, preferably 0.35×Y to 0.6×Y position, more preferably 0.40×Y to 0.55×Y position from the viewpoint of further improving fogging resistance. , more preferably 0.40×Y to 0.50×Y.

In the extruder 10, the extrusion direction distance Y from the main hopper 3 to the discharge port 4 is not particularly limited, and may be, for example, 500 to 50000 mm, particularly 1000 to 10000 mm, preferably 1000 to 5000 mm.

The degree of pressure reduction when the side vacuum device 12 is used is preferably −0.06 MPa or less, more preferably −0.08 MPa or less, in terms of pressure gauge numerical value, from the viewpoint of further improving fogging resistance.

The thermal conductivity of the resin composition of the present invention must be 2.0 W/(mK) or more, and from the viewpoint of further improving thermal conductivity, it is preferably 5.0 W/(mK) or more. More preferably, it is 10.0 W/(m·K) or more. If the thermal conductivity is less than 2 W/(m·K), a molded product may not exhibit a sufficient heat dissipation effect. The upper limit of the thermal conductivity is not particularly limited, and the thermal conductivity is usually 50 W/(m·K) or less, particularly 45 W/(m·K) or less.

The thermal conductivity of a resin composition is the thermal conductivity of a molded article produced using the resin composition. Specifically, the thermal conductivity of the resin composition is calculated from the thermal diffusivity α, the density ρ and the specific heat Cp in the flow direction (i.e. injection direction) of a test piece manufactured by an injection molding method according to ASTM D790. A value equivalent to “α×ρ×Cp” is used.
The thermal diffusivity α may be measured using any device as long as it can measure the thermal diffusivity in the flow direction of the molded body. Co.)) can be used for measurement.
The density ρ may be measured using any device as long as it is capable of measuring the density of the compact, for example, it can be measured using an electronic hydrometer ED-120T (manufactured by Mirage Trading Co., Ltd.).
The specific heat Cp may be measured using any device as long as it can measure the specific heat of the molded body. It can be measured at a temperature rate of 10°C/min.

The haze value of the resin composition of the present invention must be 8.0 or less, preferably 7.5 or less, more preferably 6.5 or less from the viewpoint of further improving thermal conductivity. When the haze value is more than 8.0, sufficient fogging resistance cannot be obtained when formed into a molded article. The lower limit of the thermal haze value is not particularly limited, and the haze value is usually 0.1 or more, particularly 0.5 or more.

The haze value of a resin composition is the haze value of a glass plate when a molded article manufactured using the resin composition is subjected to a fogging test. Specifically, the haze value of the resin composition was measured by placing 12 test pieces of 50 mm × 15 mm × 2 mm, which were manufactured by injection molding, in an air collection bottle covered with a glass plate, in a high temperature environment of 125 ° C. The increment of the haze value in the glass plate when subjected to the time-retaining fogging test is used.
The haze value may be measured using any device as long as it can measure the haze value of a glass plate. For example, it can be measured using a haze meter (Haze Meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.). can.

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

Specific examples of molded articles obtained by molding the resin composition of the present invention include electrical and electronic parts such as sockets, relay parts, coil bobbins, optical pickups, oscillators, and computer-related parts; VTRs, televisions, irons, Home appliance parts such as air conditioners, stereos, vacuum cleaners, refrigerators, rice cookers, lighting fixtures; Heat dissipation materials for releasing heat from electronic parts such as heat dissipation sheets, heat sinks, and fans to the outside; Lamp sockets, lamp reflectors, lamps Lighting equipment parts such as housings; Acoustic product parts such as compact discs, laser discs (registered trademark) and speakers; Communication equipment parts such as ferrules for optical cables, mobile phones, landline phones, facsimiles, and modems; Separation claws, heater holders, etc. Related parts for copiers and printers; Machine parts and automotive mechanical parts such as impellers, fan gears, gears, bearings, motor parts and cases; Automobile parts such as engine parts, engine room internal parts, electrical parts, and interior parts; cooking utensils such as microwave cooking pots and heat-resistant tableware; space equipment parts and sensor parts for aircraft and spacecraft.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited only to the examples. The measurement methods used to evaluate the resin compositions of Examples and Comparative Examples are as follows.

A. Evaluation method (1) Relative viscosity Dissolved in 96% sulfuric acid to prepare a sample solution with a concentration of 1 g/dL. Subsequently, using an Ubbelohde viscometer, the falling time of the sample solution and the solvent was measured at a temperature of 25° C., and the relative viscosity was determined using the following formula.
Relative viscosity = (dropping time of sample solution) / (dropping time of solvent only)

(2) Density Measured at a temperature of 20°C using an electronic hydrometer (manufactured by Kyoto Electronics Industry Co., Ltd.).

(3) Flow length A sufficiently dried resin composition was molded using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.: NEX110-12E) equipped with a bar flow test mold (spiral shape) having a width of 20 mm and a thickness of 1 mm. Ten times of injection molding were performed, and the average was taken as the bar flow length. The cylinder temperature and mold temperature were the temperatures shown in the table, and the injection pressure was 150 MPa. Under the same resin temperature conditions, the longer the flow length, the better the molding fluidity. The flow length evaluation criteria are as follows.
◎: 115 mm or more (best);
○: 55 mm or more and less than 115 mm (good);
x: Less than 55 mm (problematic in practice).

(4) Flexural strength, flexural modulus Measured according to ISO standard 178. The evaluation criteria for bending strength and bending elastic modulus are as follows.
· Bending strength ◎: 85 MPa or more (best);
○: 75 MPa or more and less than 85 MPa (good);
x: Less than 75 MPa (problem in practice).
· Flexural modulus ◎: 8 GPa or more (best);
○: 5.5 GPa or more and less than 8 GPa (good);
x: Less than 5.5 GPa (problematic in practice).

(5) Thermal conductivity (thermal conductivity of molded body)
The thermal conductivity λ was calculated by the following formula as the 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)
Specifically, the thermal diffusivity α was measured by the following method. Four bending test pieces prepared according to ASTM D790 are hot-pressed at a temperature above the melting point of the resin using a special mold having a cavity with the same width and length (longitudinal length) as the bending test piece. pasted together by The laminate was cut so that the width (thickness) direction of the resulting test piece was parallel to the flow direction during injection molding, and the resulting test piece had a width of 1 mm to 1.5 mm. . Using the obtained test piece, the direction of resin flow was measured with a thermal constant measuring device TC-7000 (manufactured by ULVAC-RIKO Co., Ltd.) based on the laser flash method. According to ASTM D790, specimens are made by an injection molding process.
The density ρ was measured using an electronic hydrometer ED-120T (manufactured by Mirage Trading Co., Ltd.) and a bending test piece prepared according to ASTM D790.
The specific heat Cp was measured using a differential scanning calorimeter DSC-7 (manufactured by PerkinElmer) and a bending test piece prepared according to ASTM D790 under the condition of a heating rate of 10°C/min.
The thermal conductivity in the flow direction was calculated by the above method. For each of α, ρ and Cp, an average value based on measured values of 10 test pieces was used.
Regarding the thickness direction, the same method as the above method for calculating the thermal conductivity in the flow direction except that the sample was prepared using a bending test piece prepared in accordance with ASTM D790 so that the thickness was 1 mm to 1.5 mm. Then, the thermal conductivity in the thickness direction was calculated.
Thermal conductivity in the flow direction was evaluated based on the following criteria.
◎: 10.0 or more (best);
○: 5.0 or more and less than 10.0 (good);
△: 2.0 or more and less than 5.0 (practically no problem);
x: Less than 2.0 (problem in practice).

(6) Anti-fogging property A sufficiently dried resin composition was molded into a plate molding having dimensions of 50 mm x 90 mm x 2 mm thickness using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.: NEX110-12E). Each of the obtained two molded bodies was cut into 6 equal parts (15 mm wide) to obtain sample pieces. As shown in FIG. 2A, a sample piece 21 is placed in an air collection bottle 22, and this is placed in an oil bath 24 containing silicone oil 23 heated to 125° C. in the height direction of the air collection bottle. The bottle was installed so that it was submerged up to about 80% of the height, and the opening of the bottle was covered with a glass plate 25 having a thickness of 2 mm. The glass plate had dimensions of 80 mm x 80 mm x 2 mm thick. The collection bottle had dimensions of 85 mm base diameter, 150 mm height, and 50 mm inner diameter at the mouth, as shown in FIG. 2B. The size of the glass plate is not particularly limited as long as it has a size that completely covers the opening of the air collecting bottle. Also, grease may be applied to the mouth portion of the air collecting bottle in order to improve adhesion.
After being left in this state for 200 hours, the glass plate was removed from the air collecting bottle and sufficiently cooled. When the glass plate was sufficiently cooled, the haze value at any 10 points in the portion of the glass plate where the air collecting bottle was covered was measured with a haze meter (Haze Meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.). The haze value A was the average value of these measured values. The average value of the haze values of arbitrary 10 points on the glass plate before being used as a lid was 0.1, and this average value was defined as the haze value B. The value of "Haze value A - Haze value B" was evaluated based on the following criteria.
◎: 6.5 or less (best);
○: more than 6.5 and 7.5 or less (good);
△: more than 7.5 and 8.0 or less (practically no problem);
×: more than 8.0 (problematic in practice).

(7) Surface Glossiness Using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.: NEX110-12E), the sufficiently dried resin composition was molded into a plate molding having dimensions of 120 mm×105 mm×2 mm thickness. The specular surface of the mold is #1000. The surface glossiness of the central portion of the obtained molded product was measured at 60° using a handy gloss meter PG-IIM (manufactured by Nippon Denshoku Industries Co., Ltd.). The surface gloss value was evaluated based on the following criteria.
◎: 55 or more (best);
○: 50 or more and less than 55 (good);
△: 45 or more and less than 50 (practically no problem);
x: less than 45 (problematic in practice).

(8) Grain Feeling The central portion of the plate molded body obtained in (7) was measured for G value using mac-i (manufactured by BYK). Grainy feeling values were evaluated based on the following criteria.
◎: 3.0 or less (best);
○: more than 3.0 and 5.0 or less (good);
△: more than 5.0 and 7.0 or less (no practical problem);
×: 7.0 or more (problematic in practice)

B. Raw Materials Raw materials used in Examples and Comparative Examples of the present invention are shown below.
(1) Thermoplastic resin (A)
・PA6: Polyamide 6 (relative viscosity 2.6, density 1.13 g/cm ³ )
PA66: Polyamide 66 resin obtained by polymerization of hexamethylenediamine and adipic acid (relative viscosity 2.8, density 1.14 g/cm ³ )
Amorphous PA: amorphous polyamide (isophthalic acid/terephthalic acid/1,6-hexamethylenediamine cocondensate, G21 manufactured by EMS, density 1.18 g/cm ³ )

(2) Flaky graphite (B)
・GrA: flaky graphite (average particle size 40 μm, thermal conductivity 100 W/m·K, density 2.25 g/cm ³ )
・GrB: flaky graphite (average particle size 80 μm, thermal conductivity 100 W/m·K, density 2.25 g/cm ³ )
・GrC: flaky graphite (average particle size 130 μm, thermal conductivity 100 W/m·K, density 2.25 g/cm ³ )
・GrD: flake graphite (average particle size 250 μm, thermal conductivity 100 W/m·K, density 2.25 g/cm ³ )
・GrE: flaky graphite (average particle size 500 μm, thermal conductivity 100 W/m·K, density 2.25 g/cm ³ )
・GrF: flaky graphite (average particle size 650 μm, thermal conductivity 100 W/m·K, density 2.25 g/cm ³ )

(3) fibrous filler (C)
・ GF: Glass fiber (T-262H manufactured by Nippon Electric Glass Co., Ltd., average fiber diameter 11 μm, average fiber length 3 mm)

Example 1
40 parts by mass of polyamide 6 resin (PA6) and 40 parts by mass of flake graphite (GrA) were passed through a shaft extruder (manufactured by Toshiba Machine: TEM26SS, screw diameter 26 mm, main hopper 3 to discharge port 4, as shown in FIG. 1). (extrusion direction distance Y=1380 mm) 10, and melted and kneaded at 260°C. 20 parts by mass of the fibrous reinforcing material (C) was supplied from a side feeder (“11” in FIG. 1) during melting and kneading. At that time, the side vacuum device 12 was used at one place. As described above, the side vacuum device 12 is a device that reduces the pressure in the extruder 10 while preventing backflow of the melted material from the extruder 10 by rotating the internal screw. The degree of pressure reduction in the side vacuum device 12 was −0.07 MPa as indicated by the value of the pressure gauge. The installation position X ₁₂ (see FIG. 1) of the side vacuum device 12 is a position of 0.70×Y when the distance in the extrusion direction from the main hopper 3 to the discharge port 4 in the extruder 10 is Y (mm). rice field. The installation position X ₁₁ (see FIG. 1) of the side feeder 11 is 0.45×Y when the distance in the extrusion direction from the main hopper 3 to the discharge port 4 in the extruder 10 is Y (mm). . The melt was sufficiently melted and kneaded, extruded into strands, cooled and solidified, and then cut with a pelletizer to obtain pellets of the resin composition.
For the evaluation of flexural strength, thermal conductivity and anti-fogging properties, the obtained pellets were molded into the predetermined shape described above using a molding machine (NEX110-12E) manufactured by Nissei Plastics Co., Ltd.
For other evaluations and measurements, pellets of the resin composition were used.

Examples 2-9 and Comparative Examples 1-6
Except for changing the resin composition, kneading conditions, molding conditions and side vacuum device (presence or absence) as shown in Table 1, the same operation as in Example 1 was performed to obtain pellets of the resin composition.
When the side vacuum device was not used, a general standard vacuum device without a screw was installed at the vent port 5 and used.

Table 1 shows the resin composition, kneading conditions, molding conditions, side vacuum device (with or without), and characteristic values of the obtained resin composition.

Since the resin compositions of Examples 1 to 9 satisfy the requirements of the present invention, a molded article having a thermal conductivity of 2 W/(m·K) or more and having excellent design properties and anti-fogging properties can be obtained. I was able to The resin compositions of Examples 1 to 5 and the resin compositions of Examples 7 to 9 contained glass fiber as a fibrous reinforcing material in an appropriate amount, and thus were excellent in bending properties.

Since the resin composition of Example 8 contained amorphous polyamide, the haze value in the fogging test was smaller than that of Example 1 containing no amorphous polyamide.

Comparing the resin compositions of Examples 1 to 3, the larger the particle size of the thermally conductive filler, the higher the thermal conductivity.

Since the resin composition of Example 7 contained a large amount of fibrous reinforcing material, the bending property was improved, but the molding fluidity and the surface glossiness were lowered.

In the resin compositions of Comparative Examples 1 and 2, the mean particle size of the flake graphite was small, so the surface gloss was low and the design was poor.
In the resin composition of Comparative Example 3, since the scale-like graphite had a large average particle size, the particles appeared on the surface, giving a strong grainy feel and poor design.
The resin composition of Comparative Example 4 had a high haze value after the fogging test because the mass ratio of flake graphite was larger than the range specified in the present invention.
In the resin composition of Comparative Example 5, the mass ratio of flake graphite was smaller than the range specified in the present invention, so sufficient thermal conductivity could not be obtained.
Since the resin composition of Comparative Example 6 did not use a side vacuum device, the haze value after the fogging test was high.

Claims (6)

A thermally conductive resin composition containing a thermoplastic resin (A) and flake graphite (B) having an average particle size of 100 to 500 μm,
The mass ratio of the thermoplastic resin (A) and the flake graphite (B) is 38/62 to 85/15,
The glass plate has a haze value of 8 or less after a fogging test at 125 ° C. for 200 hours,
A thermally conductive resin composition, wherein a molded body obtained by molding the thermally conductive resin composition has a thermal conductivity in the flow direction of 2 W/(m·K) or more. The thermally conductive resin composition further contains a non-thermally conductive fibrous reinforcing material (C), the sum of the thermoplastic resin (A) and the flake graphite (B) and the non-thermally conductive fibrous 2. The thermally conductive resin composition according to claim 1, wherein the mass ratio to the reinforcing material (C) is 100/0 to 50/50. The thermally conductive resin composition according to claim 1, wherein the non-thermally conductive fibrous reinforcing material (C) is glass fiber. The thermally conductive resin composition according to any one of claims 1 to 3, wherein the thermoplastic resin (A) is polyamide. Claims 1 to 1, wherein the thermoplastic resin (A) is composed of a crystalline polyamide and an amorphous polyamide, and the mass ratio of the crystalline polyamide and the amorphous polyamide is 100/0 to 40/60. 5. The thermally conductive resin composition according to any one of 4. A molded article made of the thermally conductive resin composition according to any one of claims 1 to 5.

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