JP2023083106A - Method for producing resin composition, mixture, resin composition and molding - Google Patents

Abstract

To provide a method for producing a resin composition that allows for stable improvements in heat radiation properties and dielectric properties while reducing the deterioration of mechanical properties.SOLUTION: A method for producing a resin composition (A) includes the steps of: removing moisture from a thermally conductive filler (b); and melting and mixing a thermoplastic resin (a) and the thermally conductive filler (b) from which the moisture has been removed, while maintaining the moisture content of the thermally conductive filler (b) with its moisture having been removed.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for producing a resin composition, a mixture, a resin composition and a molded article.

Resin compositions filled with fillers are used in various fields as materials having various properties. 2. Description of the Related Art In recent years, with regard to heat dissipation properties, for example, the demand for resin heat dissipating materials with high thermal conductivity has been increasing along with the integration and miniaturization of electronic devices, automobiles, etc., and the miniaturization and high output of motors, inverters, and the like. Regarding dielectric properties, substrates for communication modules for applications such as 5G and autonomous driving are used in higher frequency bands than existing applications, and in addition to reducing signal delay, loss, and heat generation, further miniaturization and weight reduction are required. there is

As a conventional method for producing a resin composition, it is disclosed that the water absorption rate of ceramic particles can be reduced by synthesizing ceramic particles by a flame fusion method. In the ceramic particles, the total amount of (I) Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more in the ceramic composition, and (II) Al ₂ O ₃ or MgO and SiO ₂ The weight ratio [(Al ₂ O ₃ or MgO)/SiO ₂ ] is 0.1 to 15, and (III) the sphericity is 0.9 or more. Further, the resin composition obtained by the present production method contains the ceramic particles in the base resin, the tan δ ratio of the ceramic particles to the base resin is 0.82 or less, and the thermal conductivity ratio is 1.5 or more (see Patent Document 1).

In addition, as other conventional resin compositions, reinforcing fibers mainly composed of metal silicate fibrous substances in thermoplastic resins or thermosetting resins are added in an amount of 5 to 5, based on the total weight of the resin and fibers. A resin composition for high-frequency electronic parts is disclosed that contains 60% (see Patent Document 2). It is said that this resin composition can achieve a low dielectric loss tangent under conditions of 3 GHz or 30 GHz and 25°C.

In addition, as another conventional resin composition, the average particle diameter (D50) is 1 to 5 μm, and the dehydration amount (700° C. dehydration amount) when heated to 100 to 700° C. is 13.0 to 14.5%. Some aluminized boehmite (A), epoxy resin (C-1), cyanate ester compound (C-2), maleimide compound (C-3), phenolic resin (C-4), acrylic resin (C- 5) any one or more thermosetting compounds (C) selected from the group consisting of polyamide resins (C-6), polyamideimide resins (C-7) and thermosetting polyimide resins (C-8); is disclosed (see Patent Document 3). It is said that this resin composition can achieve a low dielectric loss tangent at 1 GHz.

JP 2008-120877 A JP-A-08-134263 JP 2016-113592 A

However, when the resin composition is used in a higher frequency band than in existing applications, it is required to stably exhibit better dielectric properties, so there is still room for improvement. Moreover, even if the filler is dry when the filler is produced by using a flame melting method or the like, the filler absorbs moisture to some extent over time depending on the storage conditions. Therefore, when the stored filler is added to the base resin to produce a resin composition, there is a problem that the dielectric loss tangent (tan δ) deteriorates due to the polarization of water at the interface between the fillers. Furthermore, depending on the type of the base resin, water adsorbed on the filler may cause hydrolysis of the base resin, resulting in deterioration of mechanical properties.

In addition, if the filling rate of the filler is increased in order to make the resin composition have high thermal conductivity, the content of the resin is relatively decreased. invite. Therefore, the method of simply increasing the filling rate of the filler has a limit in improving the heat radiation property while suppressing the deterioration of the moldability and mechanical properties.

An object of the present invention is to provide a method for producing a resin composition, a mixture, a resin composition, and a molded article that can achieve stable improvement in heat dissipation properties and dielectric properties while suppressing deterioration in mechanical properties. aim.

In order to achieve the above object, the inventors have conducted extensive research, and as a result, reduced the hydroxyl groups that are easily polarized from the surface of the filler having thermal conductivity, and the filler having thermal conductivity with the hydroxyl groups reduced. It was found that the dielectric loss of the resin composition can be stably reduced by mixing with the base resin. In addition, by hydrophobizing the surface of the thermally conductive filler, the hydrolysis of the thermoplastic resin, which is the base resin, is suppressed, and the adhesion of the thermoplastic resin / filler interface is improved, improving thermal conductivity. I found what I can do.

That is, the present invention provides the following means.
[1] a step of removing moisture from the filler (b) having thermal conductivity;
The thermoplastic resin (a) and the thermally conductive filler (b) from which the moisture has been removed are combined while maintaining the moisture content of the thermally conductive filler (b) from which the moisture has been removed. a step of melting and kneading;
A method for producing a resin composition.

[2] The method for producing a resin composition according to [1] above, wherein the thermally conductive filler (b) from which moisture has been removed has a moisture content of 2000 ppm or less.

[3] The thermally conductive filler (b) is [Mg] _x [T] _y O ₄ (wherein T is silicon or aluminum, x and y are each greater than 0 and less than 3, The sum of x and y is 3.).

[4] The resin composition according to [1] above, wherein the step of removing moisture from the thermally conductive filler (b) removes moisture from the thermally conductive filler (b) with a heated airflow. Production method.

[5] The step of removing moisture from the thermally conductive filler (b) includes pulverizing the thermally conductive filler (b) and reducing the thermal conductivity by a jet mill in which a heated air stream is formed. The method for producing a resin composition according to [4] above, wherein the water content of the filler (b) is removed.

[6] After the step of removing moisture from the thermally conductive filler (b), the thermoplastic resin (a) and the thermally conductive filler (b) from which moisture has been removed are The method according to any one of the above [1] to [5], further comprising a step of subjecting the surface of the filler (b) having thermal conductivity from which moisture has been removed to a hydrophobic treatment before the step of melting and kneading. A method for producing a resin composition.

[7] When the total mass of the resin composition is 100% by mass in the step of melt-kneading the thermoplastic resin (a) and the thermally conductive filler (b) from which moisture has been removed The content of the thermally conductive filler (b) from which moisture has been removed or the thermally conductive filler (b) whose surface has been hydrophobized is 7% by mass or more and 90% by mass or less. The method for producing the resin composition according to any one of [1] to [6] above, wherein the resin composition is blended as follows.

[8] The resin composition obtained by the method for producing a resin composition according to any one of [1] to [7] above is used as a masterbatch, and the masterbatch and the diluent resin (c) are melted. A method for producing a resin composition, including a kneading step.

[9] A mixture containing a thermoplastic resin (a) and a thermally conductive filler (b),
The thermally conductive filler (b) is a composite oxide,
When the total mass of the mixture is 100% by mass, the content of the thermally conductive filler (b) is 7% by mass or more and 90% by mass or less,
The mixture, wherein the thermally conductive filler (b) has a moisture content of 2000 ppm or less.

[ ₁₀ ] The thermally conductive filler (b) is [Mg] _x [T] _yO4 , where T is silicon or aluminum, x and y are each greater than 0 and 2 or less, and x and y are 3 in total.), which is an oxide solid solution represented by [9] above.

[11] The mixture according to [9] above, wherein the thermally conductive filler (b) has a moisture content of 1500 ppm or less.

[12] The mixture according to [11] above, wherein the thermally conductive filler (b) has a moisture content of 1000 ppm or less.

[13] A resin composition containing a thermoplastic resin (a) and a thermally conductive filler (b),
The thermally conductive filler (b) is a composite oxide,
The content of the thermally conductive filler (b) when the total mass of the resin composition is 100% by mass is 7% by mass or more and 90% by mass or less,
A resin composition having a dielectric loss tangent (tan δ) at a frequency of 1 GHz of 0.01 or less.

[14] The resin composition according to [13] above, which has a dielectric loss tangent (tan δ) at a frequency of 10 GHz of 0.002 or less.

[15] The resin composition according to [13] above, which has a thermal conductivity of 0.5 W/m·K or more by a xenon flash method.

[16] The resin composition according to [15] above, wherein the thermal conductivity is 1.7 W/m·K or more.

[17] A molded article obtained by melt-molding the resin composition according to any one of [13] to [16] above.

[18] The molded article according to [17] above, which is a substrate for a communication module.

ADVANTAGE OF THE INVENTION According to this invention, the heat dissipation property and dielectric property can be stably improved, suppressing the deterioration of the mechanical property of a resin composition.

Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments.
<Method for producing resin composition (A)>
The method for producing the resin composition (A) according to the present embodiment includes a step of removing moisture from the thermally conductive filler (b), and a step of removing the moisture from the thermally conductive filler (b) ), the thermoplastic resin (a) and the thermally conductive filler (b) from which the moisture has been removed are melt-kneaded while maintaining the moisture content of the method. Other steps may be included before the water removal step, after the melt-kneading step, or between these two steps without departing from the scope of the present invention.

(Step of removing moisture from filler (b) having thermal conductivity)
The method for removing moisture from the thermally conductive filler (b) is not particularly limited, but, for example, the thermally conductive filler (b) is dehydrated with a heated air stream. A heated airflow can be formed by heating a predetermined gas with an electric heater, a steam heater, a petroleum burner, or the like. The temperature of the gas is not limited as long as it does not affect the performance of the thermally conductive filler (b), but is preferably 100° C. or higher, more preferably 200° C. or higher. If the temperature of the heated airflow is within this range, the moisture contained in the thermally conductive filler (b) can be sufficiently removed, and the occurrence of molding defects due to moisture can be suppressed. On the other hand, an organic compound may be applied to the surface treatment agent or the like of the filler (b) having thermal conductivity, and the temperature is preferably 300° C. or lower in order to prevent thermal decomposition.

The gas used to form the heated airflow is not particularly limited as long as it does not adversely affect the performance of the thermally conductive filler (b) or the dispersion of the thermally conductive filler (b) in the polyolefin. can be used without Such gases include, for example, air or dry air, inert gases such as nitrogen, argon and helium, and mixed gases thereof. Among these, dry air is preferable because it is readily available and has a high dehydrating effect on the thermally conductive filler (b).

When a heated air stream is used in this step, it is preferable to pulverize the thermally conductive filler (b) and remove moisture from the thermally conductive filler (b) by a jet mill in which the heated air stream is formed. The jet mill used in this step accelerates the thermally conductive filler (b) by a jet stream formed by ejecting compressed air or high-pressure gas of several atmospheres or more from an injection nozzle, and accelerates the thermal conductivity. It is a pulverizer that advances pulverization by colliding or grinding the fillers (b), or by causing accelerated particles to collide with a collision plate. As a result, it is possible to remove moisture from the thermally conductive filler (b) and obtain the thermally conductive filler (b) having a predetermined particle size.

The jet mill may be of vertical type or horizontal type. In addition, the crushing method of the jet mill may be any method such as an opposing collision type or a whirling airflow method, but the filler (b) having thermal conductivity causes less wear and has a thermal conductivity that leads to a reduction in the crushing effect. It is preferable to have a structure in which the filler (b) having

Examples of the thermally conductive filler (b) _used in the present invention include [Mg] _x [T] _yO4 (wherein T is silicon or aluminum, and x and y are each greater than 0 to 3 is less than x and y are 3 in total.). That is, 0<x<3, 0<y<3, x+y=3 (one significant digit), preferably 0<x<3.0, 0<y<3.0, x+y=3.0 ( 2 significant digits). When the thermally conductive filler (b) has the above composition, good thermal conductivity can be exhibited.

Specifically, the thermally conductive filler (b) is, for example, a spinel-type composite oxide. The spinel-type composite oxide preferably contains Mg element, and examples thereof include MgAl ₂ O ₄ . A further example is an olivine-type composite oxide. The olivine-type composite oxide preferably contains silicon element, such as Mg2SiO4.

The shape of the thermally conductive filler (b) is not particularly limited, and may have various shapes such as irregular shape, plate shape, and spherical shape. The thermally conductive filler (b) may be solid, hollow, or porous.

The water content (also referred to as water content) of the thermally conductive filler (b) obtained in this step is preferably 2000 ppm or less, more preferably 1500 ppm or less, and further preferably 100 ppm or less. preferable. When the water content of the thermally conductive filler (b) is 2000 ppm or less, it is possible to obtain a resin composition having excellent thermal conductivity and excellent dielectric loss tangent at 1 G, which is a high frequency band. In addition, since the water content of the filler (b) having thermal conductivity is 1500 ppm or less, it is possible to obtain a resin composition that has excellent thermal conductivity and excellent dielectric loss tangent in high frequency bands of 1 G and 10 G. can be done. Furthermore, since the water content of the filler (b) having thermal conductivity is 1000 ppm or less, the resin has excellent thermal conductivity and dielectric loss tangent at 1 G and 10 G, which are high frequency bands, and further has an excellent relative dielectric constant. A composition can be obtained.

(polyhedral spinel particles)
The thermally conductive filler (b) may be polyhedral spinel particles. Polyhedral spinel particles, for example, preferably have an average particle size of 0.1 to 1000 μm, more preferably 0.2 to 100 μm, even more preferably 0.3 to 80 μm, 0.4 to 60 μm is particularly preferred. In this specification, the term "polyhedron" usually means a hexahedron or more, preferably an octahedron or more, and more preferably a 10- to 30-hedron.

In general, "spinel particles _" contain magnesium atoms, aluminum atoms, and oxygen atoms, and are usually represented by the chemical composition _MgAl2O4 . The polyhedral spinel particles according to the embodiment contain molybdenum in the particles, and the molybdenum content is not particularly limited. is incorporated into the spinel, and combinations thereof. At this time, the "form in which molybdenum is incorporated into the spinel" includes a form in which at least part of the atoms constituting the spinel particle is substituted with molybdenum, a space that can exist inside the crystal of the spinel particle (a space caused by a defect in the crystal structure). etc.) in which molybdenum is arranged. In the substitution mode, atoms constituting the spinel particles to be substituted are not particularly limited, and may be magnesium atoms, aluminum atoms, oxygen atoms, or other atoms.

Among them, molybdenum is preferably contained at least in the form incorporated into the spinel. When molybdenum is incorporated into the spinel, it tends to be difficult to remove by washing, for example.

The thermally conductive filler (b) is polyhedral spinel particles having the above shape, so that the dielectric loss tangent is kept low and the mechanical strength is excellent.

In addition, the polyhedral spinel particles may contain other unavoidable impurities, other atoms, etc. as long as the effects of the present invention are not impaired.

(Step of melt-kneading thermoplastic resin (a) and thermally conductive filler (b))
In this step, as described above, while maintaining the moisture content of the thermally conductive filler (b) in a state where the moisture is removed, the thermoplastic resin (a) and the thermally conductive filler (b) from which the moisture is removed The filler (b) having properties is melt-kneaded. As a result, the thermally conductive filler (b) whose surface is sufficiently hydrophobized can be brought into close contact with the thermoplastic resin (a).
The melt-kneading performed in this step is performed using a melt-kneader. Examples of the melt-kneader include a single-screw extruder and a twin-screw extruder. In addition, after kneading the filler (b) having thermal conductivity and the thermoplastic resin (a) dehydrated with a heated air stream with a batch type kneader such as a pressure kneader or a Banbury mixer without directly supplying it to the melt kneader, It may be supplied to a melt-kneader and melt-kneaded.

As a method of supplying the thermally conductive filler (b) dehydrated in the water removal step to the melt-kneader for continuously melt-kneading it with the thermoplastic resin (a) in this step, first, a bag The thermally conductive filler (b) is collected with a collector such as a filter, and then the collected thermally conductive filler (b) is fed to the feeder of the melt kneader using a screw conveyor or the like. A method of conveying and supplying to a melt-kneader may be mentioned. At this time, the filler (b) having thermal conductivity collected by a bag filter or the like is transported to a mixer before being transported to the feeder of the melt kneader, mixed with the thermoplastic resin (a), and then mixed with the feeder of the melt kneader. It may be conveyed to and supplied to the melt kneader. In addition, in the transfer process from the removal of moisture from the thermally conductive filler (b) to the feeder of the melt kneader, the structure suppresses the rehydration of the thermally conductive filler (b) dehydrated by the heated air flow. is preferred. As such a structure, for example, it is preferable to form a sealed structure in which the inside of the portion through which the inorganic pigment passes in the transporting process is replaced with dehumidified air.

The thermally conductive filler (b) dehydrated in the water removal step is preferably weighed separately from the thermoplastic resin (a) before being supplied to the melt-kneader. Similarly, the thermoplastic resin (a) is preferably weighed before being supplied to the melt-kneader. The thermally conductive filler (b) or thermoplastic resin (a) is weighed using a weight control feeder or a volume control feeder as the feeder of the melt kneader, but the weight control feeder is preferred. It is preferable because the accuracy of weighing is high.

In addition, in order to continuously perform the water removal step and the melt-kneading step, the feed rate of the filler (b) having thermal conductivity in the water removal step to the heated air stream and the melt-kneading step It is preferable to set the feeding speed of the filler (b) having thermal conductivity to the melt-kneader at about the same speed. By setting these supply speeds to approximately the same speed, the moisture removal step and the melt-kneading step can be performed smoothly and continuously. In addition, in order to make these supply speeds substantially the same, the supply speed of the filler (b) having thermal conductivity in the moisture removal step and the filler having thermal conductivity in the melt kneading step The difference from the feed rate to the melt kneader in (b) is preferably within ±10%, more preferably within ±5%.

In this step, the essential components of the thermoplastic resin (a) and the thermally conductive filler (b), and optionally other raw material components, are mixed in the form of bulk, pellet, chip, or the like. may be blended in various forms to achieve a predetermined blending ratio. Next, after premixing as necessary, the mixture may be put into a melt-kneader and melt-kneaded.
The form of the melt-kneaded product is not particularly limited as long as the effect of the present invention is not impaired. For example, the melt-kneaded product can be directly made into a resin composition or a molded article. Alternatively, while the melt-kneaded product is in a molten state, a diluent resin (C), which will be described later, may be added directly to obtain a resin composition or molded product, or the product may be extruded into strands and then cut into pellets. , may be in the form of granules such as chips.

Premixing is not particularly limited as long as it does not impair the effects of the present invention, and dry blending using a ribbon blender, a Henschel mixer, a V blender, or the like can be mentioned. The melt-kneader is not particularly limited as long as it does not impair the effects of the present invention, but examples thereof include melt-kneaders equipped with a heating mechanism such as Banbury mixers, mixing rolls, single-screw or twin-screw extruders, and kneaders. be able to. In addition, the melt kneader in the above step may be loaded with a filter having an opening of preferably 100 µm or less, more preferably 50 µm or less, and even more preferably 30 µm or less.

In this step, the content of the thermally conductive filler (b) from which moisture has been removed is 7% by mass or more and 90% by mass or less when the total mass of the resin composition (A) is 100% by mass. is preferably blended so as to be 10% by mass or more and 85% by mass or less, more preferably blended so as to be 20% by mass or more and 80% by mass or less, and 30% by mass % or more and 75 mass % or less. By blending so that the content of the thermally conductive filler (b) is 7% by mass or more, it is possible to achieve stable improvement in heat dissipation properties and dielectric properties. Moreover, by blending so that the content of the thermally conductive filler (b) is 90% by mass or less, deterioration of moldability and mechanical properties can be suppressed.

The thermoplastic resin (a) used in the present invention is not particularly limited, but examples include polyolefin resins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyethylene terephthalate; , polybutylene terephthalate, polyester resins such as polyethylene naphthalate; polyamide-6 (nylon-6), polyamide 66 (nylon-66), polyamide-based resins such as polymetaxylene adipamide; ethylene-vinyl ester copolymer , ethylene/unsaturated ester copolymers such as ethylene/unsaturated carboxylic acid ester copolymers; ethylene/unsaturated carboxylic acid copolymers or ionomer resins thereof; poly(meth)acrylate resins such as poly ( Meta) acrylic resins; chlorine resins such as polyvinyl chloride and polyvinylidene chloride; fluorine resins such as polytetrafluoroethylene, ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride, and polyvinyl fluoride; polystyrene resin; polyether ether ketone polyether resins such as resins and polyether ketone resins; polycarbonate resins; polyphenylene resins such as polyphenylene oxide resins and polyphenylene sulfide resins; polyvinyl acetate resins; Moreover, one selected from these thermoplastic resins may be used alone, or two or more thereof may be used in combination.

A polyolefin resin is a polyolefin resin obtained by polymerizing at least one kind of olefin, and may be a homopolymer or a copolymer.
Examples of such olefins include ethylene, propylene, isobutylene, α-olefins having 4 to 12 carbon atoms including isobutene (1-butene), butadiene, isoprene, (meth)acrylic acid esters, (meth)acrylic acid, , (meth)acrylamide, vinyl alcohol, vinyl acetate, vinyl chloride, styrene, acrylonitrile and the like.

Examples of α-olefins having 4 to 12 carbon atoms include 1-butene, 2-methyl-1-propene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2 -ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene , 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl-1- Hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene , 1-dodecene and the like.

Examples of polyolefin resins include polyethylene resins, polypropylene resins, polyisobutylene resins, polyisobutene resins, polyisoprene resins, polybutadiene resins, and the like. Among these resins, polyethylene resins and polypropylene resins are preferred.

Classified by density or shape, high density polyethylene (HDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), ultra high molecular weight polyethylene (UHMW-PE) Among these, high-density polyethylene is preferred.

(Step of hydrophobizing the surface of the thermally conductive filler (b))
In the method for producing the resin composition (A) of the present embodiment, after the step of removing moisture from the thermally conductive filler (b), the thermoplastic resin (a) and the heat from which the moisture is removed Before the step of melt-kneading with the conductive filler (b), the surface of the thermally conductive filler (b) from which moisture has been removed may be subjected to a hydrophobic treatment. . By subjecting the surface of the thermally conductive filler (b) from which moisture has been removed to a hydrophobic treatment, it is possible to further reduce hydroxyl groups that are easily polarized from the surface of the thermally conductive filler (b). The adhesion of the thermoplastic resin (a)/thermally conductive filler (b) interface can be further improved.

When performing this hydrophobization treatment step, in the subsequent melt-kneading step, the thermally conductive filler having a hydrophobized surface ( The content of b) is preferably 7% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 85% by mass or less, and 20% by mass or more and 80% by mass. % or less, more preferably 30% by mass or more and 75% by mass or less. By blending so that the content of the thermally conductive filler (b) is 7% by mass or more, it is possible to achieve stable improvement in heat dissipation properties and dielectric properties. Moreover, by blending so that the content of the thermally conductive filler (b) is 90% by mass or less, deterioration of moldability and mechanical properties can be suppressed.

<Resin composition (A)>
The resin composition (A) of the present embodiment obtained by the above production method is a resin composition (A) obtained by blending a thermoplastic resin (a) and a filler (b) having thermal conductivity. The thermally conductive filler (b) is a composite oxide, and the content of the thermally conductive filler (b) when the total mass of the resin composition is 100% by mass is It is 7% by mass or more and 90% by mass or less, and the dielectric loss tangent (tan δ) at a frequency of 1 GHz is 0.01 or less.

In the present embodiment, the “resin composition (A)” is a product (cured product) obtained by cooling and solidifying a melt-kneaded product containing a thermoplastic resin softened and fluidized by heating. Moreover, "a resin composition formed by blending" means "a resin composition formed by blending and melt-kneading". More specifically, the "resin composition (A)" has a morphology in which a thermoplastic resin (A) is used as a matrix and thermally conductive fillers (B) are dispersed. Examples of the hardened material include a hardened material of the melt-kneaded material, or pellets obtained by pelletizing the hardened material of the melt-kneaded material.

The content of the thermally conductive filler (b) when the total mass of the resin composition (A) is 100% by mass is preferably 7% by mass or more and 90% by mass or less. , more preferably 10% by mass or more and 85% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and 30% by mass or more and 75% by mass or less. It is even more preferable to blend in As a result, it is possible to reliably achieve stable improvements in heat dissipation properties and dielectric properties, and to suppress deterioration in moldability and mechanical properties.

In the resin composition (A), the dielectric loss tangent (tan δ) at a frequency of 1 GHz is preferably 0.009 or less, more preferably 0.005 or less. As a result, it is possible to obtain a molded article having a small dielectric loss at 1 GHz, which is a high frequency band.

In the resin composition (A), the dielectric loss tangent (tan δ) at a frequency of 10 GHz is preferably 0.002 or less, more preferably 0.0015 or less, and further preferably 0.0015 or less. preferable. As a result, it is possible to obtain a molded article having a small dielectric loss at 10 GHz, which is a high frequency band.

Further, the resin composition (A) preferably has a dielectric loss tangent (tan δ) of 0.01 or less at a frequency of 1 GHz and a dielectric loss tangent (tan δ) of 0.002 or less at a frequency of 10 GHz. As a result, it is possible to obtain a compact with low dielectric loss at both frequencies of 1 GHz and 10 GHz.

In the resin composition (A), the thermal conductivity by the xenon flash method is preferably 0.5 W/m·K or more, more preferably 1.7 W/m·K or more, and 1.8 W/m·K or more. More preferably, it is m·K or more. Thereby, a molded article having high thermal conductivity can be obtained.
In the xenon flash method, for example, when the surface of a plate-shaped sample placed in an adiabatic vacuum is uniformly pulse-heated with a xenon laser, the one-dimensional thermal diffusion phenomenon from the front surface to the back surface is observed to determine the thermal diffusivity. can be asked for.

In the resin composition (A), the dielectric constant ε at a frequency of 1 GHz is preferably 3.7 or less, more preferably 3.6 or less, and more preferably 3.55 or less. . As a result, it is possible to obtain a molded article having excellent dielectric properties in a high frequency band, particularly a small signal propagation delay at 1 GHz.

In the resin composition (A), the dielectric constant ε at a frequency of 10 GHz is preferably 3.5 or less, more preferably 3.4 or less, and even more preferably 3.35 or less. . As a result, it is possible to obtain a molded article having excellent dielectric properties in a high frequency band, particularly a small signal propagation delay at 10 GHz.

[Other ingredients]
The resin composition (A) is used, for example, as a masterbatch. When the resin composition (A) is a masterbatch, the masterbatch, in addition to the essential components of the thermoplastic resin (a) and the fine particles (b), is an optional component within the scope of its function. Other components may be included as
Specific examples of other components include antioxidants, ultraviolet absorbers, colorants, pigments, dyes, foaming agents, lubricants, flame retardants, fillers, and the like. When other components are used as optional components, the mixing ratio is not particularly limited as long as it does not impair the effects of the present invention, but it is 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin (a). is preferably used in the range of , more preferably in the range of 25 parts by mass or less. By adjusting the types and amounts of these components, the intended function can be freely adjusted.

<Method for producing mixture>
Although the method for producing the resin composition (A), that is, the method for producing a melt-kneaded product has been described in the above embodiment, the following method for producing a mixture may be provided.
A method for producing a mixture includes a step of removing moisture from the thermally conductive filler (b), and heating while maintaining the moisture content of the thermally conductive filler (b) with the moisture removed. mixing the plastic resin (a) and the thermally conductive filler (b) from which moisture has been removed. The step of removing water from the thermally conductive filler (b) is the same as the method for producing the resin composition (A), including the raw materials used. The mixing step is the same as the method for producing the resin composition (A) above, except that the melt-kneading is not performed. A mixture can be easily obtained through these steps.

The water content of the thermally conductive filler (b) obtained in the water removal step is 2000 ppm or less, preferably 1500 ppm or less, and more preferably 100 ppm or less. When the water content of the thermally conductive filler (b) is 2000 ppm or less, it is possible to obtain a resin composition having excellent thermal conductivity and excellent dielectric loss tangent at 1 G, which is a high frequency band. In addition, since the water content of the filler (b) having thermal conductivity is 1500 ppm or less, it is possible to obtain a resin composition that has excellent thermal conductivity and excellent dielectric loss tangent in high frequency bands of 1 G and 10 G. can be done. Furthermore, since the water content of the filler (b) having thermal conductivity is 1000 ppm or less, the thermal conductivity is excellent and the dielectric loss tangent at 1 G and 10 G, which is a high frequency band, and the relative dielectric at 1 G and 10 G A resin composition having an excellent rate can be obtained.

In this step, when the total mass of the mixture is 100% by mass, the content of the filler (b) having thermal conductivity from which water is removed is 7% by mass or more and 90% by mass or less. It is preferably blended, more preferably 10% by mass or more and 85% by mass or less, even more preferably 20% by mass or more and 80% by mass or less, and 30% by mass or more and 75% by mass. % or less is even more preferable. By blending so that the content of the thermally conductive filler (b) is 7% by mass or more, it is possible to achieve stable improvement in heat dissipation properties and dielectric properties. Moreover, by blending so that the content of the thermally conductive filler (b) is 90% by mass or less, deterioration of moldability and mechanical properties can be suppressed.

<Mixture>
The mixture of the present embodiment obtained by the above production method is a mixture containing a thermoplastic resin (a) and a thermally conductive filler (b), wherein the thermally conductive filler (b) is a composite oxide, the content of the thermally conductive filler (b) is 7% by mass or more and 90% by mass or less when the total mass of the mixture is 100% by mass, and the thermally conductive The moisture content of the hydrophilic filler (b) is 2000 ppm or less. When the water content of the thermally conductive filler (b) is 2000 ppm or less, it is possible to obtain a resin composition having excellent thermal conductivity and excellent dielectric loss tangent at 1 G, which is a high frequency band.

In the present embodiment, the “mixture” is a mixture of a thermoplastic resin (a) and a thermally conductive filler (b), typically before melt-kneading. means.

Examples of the thermally conductive filler (B) in the mixture include [Mg] _x [T] _yO4 (wherein T is silicon or aluminum, and x and y are each greater than 0 and less than 3 ₎ . and the sum of x and y is 3.). That is, 0<x<3, 0<y<3, x+y=3 (one significant digit), or 0<x<3.0, 0<y<3.0, x+y=3.0 ( 2 significant digits). When the thermally conductive filler (b) has the above composition, good thermal conductivity can be exhibited.

The water content of the thermally conductive filler (B) in the mixture is preferably 1500 ppm or less, more preferably 1000 ppm or less. When the water content of the thermally conductive filler (b) is 1500 ppm or less, it is possible to obtain a resin composition having excellent thermal conductivity and excellent dielectric loss tangent in high frequency bands of 1 G and 10 G. . In addition, since the water content of the filler (b) having thermal conductivity is 1000 ppm or less, the thermal conductivity is excellent and the dielectric loss tangent at 1 G and 10 G, which is a high frequency band, and the relative dielectric at 1 G and 10 G A resin composition having an excellent rate can be obtained.

<Method for producing resin composition (B)>
Further, as a method for producing the resin composition (B) according to the present embodiment, the resin composition (A) obtained in the above steps is used as a masterbatch, and the masterbatch and the diluent resin (c) are melted. A kneading step may be included. Specifically, for example, the essential components of the resin composition (A) and the diluent resin (c) as a masterbatch obtained by the above-described production method, and optionally other optional components are mixed in a bulk form. , pellets, chips, etc., and blended so as to have a predetermined blending ratio and mixed. Next, for example, it is put into a melt-kneader and heated to the higher melting point of the thermoplastic resin (a) or the diluent resin (c) to melt-knead it. Thereby, another resin composition is obtained.

The diluent resin (c) is not particularly limited, but may be, for example, the same as the thermoplastic resin (a).

In this production method, the essential components of the resin composition (A) and the diluent resin (c), and optionally other raw material components, are mixed in various forms such as bulk, pellets, and chips. You may mix|blend so that it may become a predetermined|prescribed mixing ratio in a form.

The mixing ratio of the masterbatch and the diluent resin (c) is the total of the thermoplastic resin (a), the thermally conductive filler (b) and the diluent resin (c) in the resin composition (B). The content of the fine particles (b) when the mass is 100% by mass is preferably 7% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 85% by mass or less, and still more preferably 20% by mass or more and 80% by mass. It is preferably adjusted to be at most % by mass, more preferably at least 30% by mass and at most 75% by mass.

A molded article can be produced using the resin composition (B) obtained through the melt-kneading step. The molded article is not particularly limited, but includes, for example, a substrate and various molded members. The form of the melt-kneaded product is not particularly limited as long as the effect of the present invention is not impaired. For example, the resin composition (B) can be melt-molded directly from a melt-kneader to obtain a substrate. Alternatively, the resin composition (B) may be directly supplied to an injection molding machine and injection molded to obtain a molded member. In addition, after going through the step of obtaining a pellet-like or powdery resin composition (B), the desired substrate or Molded bodies can also be obtained. By obtaining the substrate or molded member via the masterbatch in this way, the thermally conductive filler can be more stably and uniformly dispersed in the substrate or molded member, and the desired functions and characteristics of the thermally conductive filler can be achieved. can be sufficiently applied to the substrate. Further, by molding the substrate through the above masterbatch, hydrolysis of the thermoplastic resin (a) is greatly suppressed, and moldability (workability), mechanical properties and appearance quality can be improved.

<Resin composition (B)>
The resin composition (B) of the present embodiment uses the resin composition (A) obtained by the method for producing the resin composition (A) as a masterbatch, and a masterbatch composed of the resin composition (A). , and a diluent resin (c).

In the present embodiment, the "resin composition (B)" is a cured product of a melt-kneaded material containing a thermoplastic resin softened and fluidized by heating, similarly to the "resin composition (A)". The cured product of the melt-kneaded product means a product obtained by cooling and solidifying a resin that has been softened and flowed by heating. The cured product is a molded article obtained by molding the resin composition (B), and the molded article is not particularly limited, but may be various molded members including substrates such as substrates for communication modules. Examples of communication modules include, but are not limited to, mobile terminals such as smartphones and mobile PCs, communication devices such as routers, and related devices.

The thermally conductive filler ( The content of b) is preferably 7% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 85% by mass or less, and even more preferably 20% by mass or more and 80% by mass or less. , more preferably 30% by mass or more and 75% by mass or less. As a result, it is possible to reliably achieve stable improvements in heat dissipation properties and dielectric properties, and to suppress deterioration in mechanical properties.

[Other ingredients]
The resin composition (B) or the molded product may contain other components as optional components in addition to the masterbatch and the diluent resin (c), which are essential components, within the scope of the function.
Specific examples of other components include antioxidants, ultraviolet absorbers, colorants, pigments, dyes, foaming agents, lubricants, flame retardants, fillers, and the like.

In the present specification, the term "substrate" refers to a thermoplastic resin molded article, and is also a general term for plate-like materials such as films and sheets, without strictly distinguishing between them. The thickness of the substrate varies depending on its application and can be any thickness, but is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm μm or less. The thickness of the substrate is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm.

Examples of the present invention will be described below. The present invention is not limited to the examples shown below.

(Production Examples 1 to 3)
First, 62.6 g of MgAl ₂ O ₄ (manufactured by Itochu Ceratec, product name “NSP-70”, 20 μm mesh pass), which is a spinel-type composite oxide S1, was transferred to an aluminum cup (bottom 60 cm ² × height 4 cm). , room temperature of 50° C. and humidity of 90% for 1 hour.
Next, the spinel-type composite oxide MgAl ₂ O ₄ is left in an oven at a temperature of 200 ° C. for the time (h) shown in Table 1, and then a Karl Fischer moisture meter (manufactured by Dia Instruments, device name "trace amount The moisture content (ppm) of MgAl ₂ O ₄ was measured using a moisture measuring device/CA-200, device name “moisture vaporizer/VA-200”.

(Production example 4)
The water content (ppm) of MgAl ₂ O ₄ was measured in the same manner as in Production Examples 1 to 3, except that it was not left in the oven.

(Production example 5)
40 g of aluminum oxide (manufactured by Wako Pure Chemical Industries, Ltd., activated alumina (average particle size 45 μm)) and 10 g of molybdenum trioxide (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a mortar. The obtained mixture was placed in a crucible and fired. Firing was performed for 10 hours at 1100 ° C. in a furnace (Asahi Rika Seisakusho, ceramic electric furnace (ARF-100K type) with a temperature controller (AMF-2P type)). After cooling to room temperature, the crucible was taken out and the contents were The product was washed with 10% aqueous ammonia and ion-exchanged water, and finally dried at 150° C. for 2 hours to obtain a blue powder of α-aluminum oxide containing molybdenum. It was crushed until it passed through a sieve.

The resulting molybdenum-containing α-aluminum oxide 1.00 g (aluminum element: 0.02 mol, molybdenum element: 0.07 mmol) and magnesium oxide (manufactured by Wako Pure Chemical Industries, Ltd.) 0.40 g (magnesium element: 0.01 mol) ) and were dry mixed in a mortar. The resulting mixture was placed in an alumina crucible and heated to 1500° C. at a heating rate of 10° C./min in an air atmosphere. After 12 hours, the mixture was naturally cooled to room temperature to produce spinel particles. The resulting powder was ground in a mortar until it passed through a 150 μm sieve.

The obtained powder had an average particle size of 5.0 μm as determined by a laser diffraction particle size distribution analyzer, and the shape of α-aluminum oxide containing molybdenum was confirmed by observation using a scanning electron microscope (SEM). It was confirmed that the particles were polyhedral particles with a nearly spherical shape. Furthermore, it was confirmed from the results of fluorescent X-ray quantitative analysis that the obtained particles contained 0.3% by mass of molybdenum in terms of molybdenum trioxide.

The water content (ppm) of MgAl ₂ O ₄ was measured in the same manner as in Production Example 3, except that the obtained particles were used as the spinel-type composite oxide S2.

(Production Examples 6 and 7)
An accelerated test was performed using a highly accelerated life test device (manufactured by Hirayama Seisakusho, device name “PC-R8D”) instead of an oven at a temperature of 121 ° C., a humidity of 100%, and the time (h) shown in Table 1. Except for this, the water content (ppm) of MgAl ₂ O ₄ was measured in the same manner as in Production Examples 1 to 3.

(Production Example 8)
100 g of magnesium hydroxide (99.2% purity) with an average particle size of 4 μm and 51.5 g of silica (99.5% purity) with an average particle size of 2.5 μm were mixed in a ball mill and fired at 1600° C. for 4 hours. The obtained sintered product was pulverized to obtain a sintered powder having an average particle size of 6 μm. Using oxygen as a carrier gas, this sintered body powder was put into a flame (flame temperature of about 2000 ° C.) in which propane gas was burned at a ratio (volume ratio) of 1.1 to oxygen, and the average particle size was 6 μm and the sphericity was 0. 0.95 ceramic particles (olivine-type composite oxide Mg ₂ SiO ₄ ) were obtained. 62.6 g of the obtained ceramic particles were transferred to an aluminum cup (bottom 60 cm ² ×height 4 cm) and left at room temperature of 50° C. and humidity of 90% for 1 hour.

The moisture content (ppm) of Mg ₂ SiO ₄ was measured in the same manner as in Production Example 3, except that the obtained particles were used as the olivine-type composite oxide S3.

(Production Example 9)
62.6 g of ceramic particles (olivine-type composite oxide Mg ₂ SiO ₄ ) obtained in the same manner as in Production Example 8 were transferred to an aluminum cup (bottom 60 cm ² × height 4 cm), and the conditions were room temperature of 50° C. and humidity of 90%. It was left in the bottom for 1 hour.
Next, the ceramic particles (olivine-type composite oxide Mg ₂ SiO ₄ ) are left in an oven at a temperature of 200° C. for the time (h) shown in Table 1, and then a Karl Fischer moisture meter (manufactured by Dia Instruments, The moisture content (ppm) of Mg ₂ SiO ₄ was measured using the device name “trace moisture measuring device/CA-200”; device name “moisture vaporization device/VA-200”).

[Examples 1 to 3]
73.3% by mass of the spinel-type composite oxide (S1) produced in Production Examples 1 to 3 and 26.7% by mass of high-density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., product name “HJ560”) were added to Laboplastomill ( A compound (resin composition) was produced by melting and kneading under conditions of 200° C. using a device name “4C150” manufactured by Toyo Seiki Seisakusho.

[Example 4]
A compound (resin composition) was produced in the same manner as in Examples 1 to 3, except that the spinel-type composite oxide S1 produced in Production Example 4 was used.

[Example 5]
A compound (resin composition) was produced in the same manner as in Examples 1 to 3, except that the spinel-type composite oxide S2 produced in Production Example 5 was used.

[Example 6]
A compound (resin composition) was produced in the same manner as in Examples 1 to 3, except that the olivine-type composite oxide S3 produced in Production Example 9 was used.

[Comparative Examples 1 and 2]
Compounds (resin compositions) were produced in the same manner as in Examples 1 to 3, except that the spinel-type composite oxide S1 produced in Production Examples 6 and 7 was used.

[Comparative Example 3]
A compound (resin composition) was produced in the same manner as in Examples 1 to 3, except that the olivine-type composite oxide S3 produced in Production Example 8 was used.

[Comparative Example 4]
A compound (resin composition) was prepared in the same manner as in Examples 1 to 3, except that neither the spinel-type composite oxides S1, S2 nor the olivine-type composite oxide S3 were added, and the high-density polyethylene was 100% by mass. made.

(evaluation)
Next, the resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were measured and evaluated by the following methods.

(Dielectric loss tangent)
The resulting resin composition is molded with a compression molding machine (manufactured by Shindo Kinzoku Kogyo Co., Ltd., device name "NF-37"), and a sample (width 1.5 mm × thickness 1.5 mm or less, length 80 mm above) was cut into strips and used as test pieces. Using this test piece, the dielectric loss tangent (tan δ) at 1 GHz with a 1 GHz cavity resonator (manufactured by Kanto Electronics Applied Development Co., Ltd.) by the cavity resonance method (manufactured by Agilent Technologies, device name "E8362C") and a cavity resonator for 10 GHz (manufactured by Kanto Denshi Applied Development Co., Ltd.).

(relative permittivity)
The relative permittivity at 1 GHz and the relative permittivity at 10 GHz were measured in the same manner as the dielectric loss tangent.

(Thermal conductivity)
The obtained resin composition is molded with a compression molding machine (manufactured by Shindo Kinzoku Kogyo Co., Ltd., device name "NF-37"), and a molded sheet with a thickness of 2 mm is cut out to form a test piece (length 10 mm × width 10 mm). bottom. The thermal conductivity of this test piece was measured by the xenon flash method (manufactured by NETZSCH, device name "LFA447 NanoFlash").The results are shown in Tables 2 and 3.

From the results in Table 2, in any of Examples 1 to 6, high-density polyethylene and MgAl ₂ O ₄ from which water was removed were mixed while maintaining the water content of MgAl ₂ O ₄ in a state where water was removed. When the resin composition is produced by melt kneading, the resin composition has a thermal conductivity of 0.5 W / m K or more and a dielectric loss tangent (tan δ) at a frequency of 1 GHz of 0.01 or less, resulting in high thermal conductivity. and a low dielectric loss tangent were obtained.
In particular, in any of Examples 1 to 6, when the water content of MgAl ₂ O ₄ when mixed with high-density polyethylene was 2000 ppm or less, the thermal conductivity of the resin composition was 1.7 W/m·K or more. In addition, the dielectric loss tangent (tan δ) of the resin composition at a frequency of 1 GHz was 0.01 or less, and high thermal conductivity and low dielectric loss tangent were obtained. In addition, it was found that the dielectric loss tangent (tan δ) at a frequency of 10 GHz was 0.002 or less, and a low dielectric loss tangent could be obtained even in a higher frequency band.

Further, when the moisture content of MgAl ₂ O ₄ when mixed with high-density polyethylene is 1500 ppm or less, the thermal conductivity of the resin composition is 1.80 W / m K or more, and the frequency of the resin composition The dielectric loss tangent (tan δ) at 1 GHz and 10 GHz was 0.011 or less and 0.0014 or less, respectively, and the dielectric constant ε at frequencies of 1 GHz and 10 GHz was 3.67 or less and 3.50 or less, respectively. Therefore, it was found that a low dielectric constant can be obtained while maintaining a favorable low dielectric loss tangent and high thermal conductivity.

Furthermore, when the moisture content of MgAl ₂ O ₄ when mixed with high-density polyethylene is 1000 ppm or less, the thermal conductivity of the resin composition is 1.80 W / m K or more, and the resin composition The dielectric loss tangent (tan δ) at frequencies of 1 GHz and 10 GHz was 0.011 or less and 0.0014 or less, respectively, and the dielectric constants ε at frequencies of 1 GHz and 10 GHz were 3.57 or less and 3.34 or less, respectively. Therefore, it was found that a lower dielectric constant can be obtained while maintaining a favorable low dielectric loss tangent and high thermal conductivity.

On the other hand, in Comparative Example 1, when the moisture content of MgAl ₂ O ₄ when mixed with high-density polyethylene was 2418.60 ppm or less, the thermal conductivity of the resin composition was 1.57 W/m K at a frequency of 1 GHz. The dielectric loss tangent (tan δ) was 0.0139, which was lower in thermal conductivity and higher in dielectric loss tangent than Examples 1-5.

In Comparative Example 2, when the moisture content of MgAl ₂ O ₄ when mixed with high-density polyethylene was 4111.50 ppm or less, the resin composition had a thermal conductivity of 1.57 W/m K and a dielectric loss tangent at a frequency of 1 GHz. (tan δ) was 0.0239, and the thermal conductivity was lower than those of Examples 1 to 5, and the dielectric loss tangent was higher.

In Comparative Example 3, when the resin composition was produced using only high-density polyethylene without containing MgAl ₂ O ₄ , the thermal conductivity was significantly lower than in Examples 1-6.

As a representative example, according to the relationship between the water content of MgAl ₂ O ₄ used in Examples 1 to 4 and Comparative Examples 1 and 2 and the dielectric loss tangent (tan δ) of the resin composition, when mixed with high-density polyethylene, When the moisture content of MgAl ₂ O ₄ is 2000 ppm or less (Examples 1 to 4), the dielectric loss tangent (tan δ) of the resin composition at frequencies of 1 GHz and 10 GHz is 0.01 or less and 0.002 or less, respectively. I understand. On the other hand, when the moisture content of MgAl ₂ O ₄ exceeds 2000 ppm (Comparative Examples 1 and 2), the dielectric loss tangent (tan δ) of the resin composition at frequencies of 1 GHz and 10 GHz exceeds 0.01 and 0.002, respectively. rice field.

Further, according to the relationship between the water content of MgAl ₂ O ₄ used in Examples 1 to 4 and Comparative Examples 1 and 2 and the thermal conductivity of the resin composition, MgAl ₂ O ₄ when mixed with high-density polyethylene is 2000 ppm or less (Examples 1 to 4), the thermal conductivity of the resin composition is 1.7 W/m·K or more. On the other hand, when the moisture content of MgAl ₂ O ₄ exceeded 2000 ppm (Comparative Examples 1 and 2), the thermal conductivity of the resin composition became less than 1.7 W/m·K.

Furthermore, according to the relationship between the water content of MgAl ₂ O ₄ used in Examples 1 to 4 and Comparative Examples 1 and 2 and the dielectric constant ε of the resin composition, MgAl ₂ O when mixed with high-density polyethylene ₄ is 2000 ppm or less (Examples 1 to 4), the dielectric constants ε at frequencies of 1 GHz and 10 GHz of the resin composition are 3.7 or less and 3.5 or less, respectively. On the other hand, when the moisture content of MgAl ₂ O ₄ exceeded 2000 ppm (Comparative Examples 1 and 2), the dielectric constants ε of the resin compositions at frequencies of 1 GHz and 10 GHz exceeded 3.7 and 3.5, respectively.

Claims (18)

a step of removing water from the filler (b) having thermal conductivity;
The thermoplastic resin (a) and the thermally conductive filler (b) from which the moisture has been removed are combined while maintaining the moisture content of the thermally conductive filler (b) from which the moisture has been removed. a step of melting and kneading;
A method for producing a resin composition. 2. The method for producing a resin composition according to claim 1, wherein the moisture content of the thermally conductive filler (b) from which moisture has been removed is 2000 ppm or less. The thermally conductive filler (b) is [Mg]x[T]yO ₄ (wherein T is silicon or aluminum, x and y are each greater than 0 and less than 3, and x and y are The method for producing a resin composition according to claim 1, which is an oxide solid solution represented by: 2. The method for producing a resin composition according to claim 1, wherein the step of removing moisture from the thermally conductive filler (b) removes moisture from the thermally conductive filler (b) with a heated airflow. The step of removing moisture from the thermally conductive filler (b) includes pulverizing the thermally conductive filler (b) and the thermally conductive filler ( 5. The method for producing a resin composition according to claim 4, wherein b) water is removed. After the step of removing moisture from the thermally conductive filler (b), the thermoplastic resin (a) and the thermally conductive filler (b) from which moisture has been removed are melt-kneaded. The resin composition according to any one of claims 1 to 5, further comprising a step of hydrophobizing the surface of the thermally conductive filler (b) from which moisture has been removed, before the step of Production method. In the step of melt-kneading the thermoplastic resin (a) and the thermally conductive filler (b) from which moisture has been removed, the above Blended so that the content of the thermally conductive filler (b) from which moisture has been removed or the thermally conductive filler (b) whose surface has been hydrophobized is 7% by mass or more and 90% by mass or less. The method for producing the resin composition according to any one of claims 1 to 6. A step of melt-kneading the resin composition obtained by the method for producing a resin composition according to any one of claims 1 to 7 as a masterbatch, and the masterbatch and the diluent resin (c). A method for producing a resin composition, comprising: A mixture containing a thermoplastic resin (a) and a thermally conductive filler (b),
The thermally conductive filler (b) is a composite oxide,
When the total mass of the mixture is 100% by mass, the content of the thermally conductive filler (b) is 7% by mass or more and 90% by mass or less,
The mixture, wherein the thermally conductive filler (b) has a moisture content of 2000 ppm or less. The thermally conductive filler (b) is [Mg]x[T]yO ₄ , where T is silicon or aluminum, x and y are each greater than 0 and less than or equal to 2, and x and y are and 3.). 10. The mixture of claim 9, wherein the thermally conductive filler (b) has a moisture content of 1500 ppm or less. 12. The mixture of claim 11, wherein the thermally conductive filler (b) has a moisture content of 1000 ppm or less. A resin composition obtained by blending a thermoplastic resin (a) and a thermally conductive filler (b),
The thermally conductive filler (b) is a composite oxide,
The content of the thermally conductive filler (b) when the total mass of the resin composition is 100% by mass is 7% by mass or more and 90% by mass or less,
A resin composition having a dielectric loss tangent (tan δ) at a frequency of 1 GHz of 0.01 or less. 14. The resin composition according to claim 13, which has a dielectric loss tangent (tan [delta]) of 0.002 or less at a frequency of 10 GHz. 14. The resin composition according to claim 13, which has a thermal conductivity of 0.5 W/m·K or more by a xenon flash method. 16. The resin composition according to claim 15, wherein said thermal conductivity is 1.7 W/m·K or more. A molded article obtained by melt-molding the resin composition according to any one of claims 13 to 16. 18. The molded article according to claim 17, wherein the molded article is a communication module substrate.