JP7815820B2 - composition - Google Patents

Description

The present invention relates to a composition containing a tetrafluoroethylene-based polymer and inorganic particles.

In recent years, in order to accommodate the increasing speed and frequency of mobile communication devices such as mobile phones, materials with high thermal conductivity, low linear expansion coefficient, low dielectric constant and low dielectric dissipation factor are required for printed circuit boards of communication devices, and tetrafluoroethylene-based polymers with low dielectric constant and low dielectric dissipation factor have attracted attention.
In addition, in order to prevent malfunctions caused by heat from high-heat-generating components due to the increasing speed and integration of circuits in electric or electronic devices and the increasing density of electronic packaging on circuit boards, materials for printed circuit boards are required to have heat dissipation properties. Furthermore, materials with excellent thermal conductivity and heat dissipation properties that can efficiently dissipate heat from electronic components are required.
In order to obtain a material with excellent low dielectric properties and thermal conductivity, a composition of a tetrafluoroethylene-based polymer and inorganic particles has been investigated. Patent Document 1 discloses a resin composition for circuit boards containing a melt-processable fluororesin and boron nitride particles having a specific particle size present in a predetermined range. Patent Document 2 discloses a composition containing a resin and hexagonal boron nitride particles whose surfaces have formed recessed structures and have been surface-treated with a metal coupling agent.

International Publication No. 2021/010320 JP 2019-137581 A

Tetrafluoroethylene-based polymers have low surface tension and low affinity with other components. In particular, in molded articles formed from compositions in which the other components are hydrophobic inorganic particles, the physical properties of each component may not be fully expressed.
The present inventors have found that it is difficult to obtain a composition from the compositions of Patent Documents 1 and 2 that can be used to form a molded article having a low linear expansion coefficient, excellent electrical properties, and particularly excellent adhesion to a substrate, thermal conductivity, and heat dissipation properties.
The present inventors have discovered that a composition containing a tetrafluoroethylene-based polymer and predetermined inorganic particles that have been surface-treated with a specific coupling agent has excellent dispersibility and moldability, and that molded products thereof have low linear expansion coefficients, dielectric constants, and dielectric dissipation factors, and are excellent in adhesion to substrates, thermal conductivity, and heat dissipation properties, thereby completing the present invention.
It is an object of the present invention to provide such a composition.

The present invention has the following aspects.
[1] A composition comprising a tetrafluoroethylene-based polymer and hydrophobic inorganic particles that have been surface-treated with a coupling agent, wherein the coupling agent is a compound in which a trialkoxysilyl group and a functional group are bonded via a linking group containing at least one bond selected from the group consisting of an imino bond, an amide bond, a urea bond, a urethane bond, and a carbodiimide bond.
[2] The composition according to [1], wherein the tetrafluoroethylene-based polymer is a heat-melting tetrafluoroethylene-based polymer having a melting temperature of 180°C or higher.
[3] The composition according to [1] or [2], wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having an oxygen-containing polar group.
[4] The composition according to any one of [1] to [3], wherein the tetrafluoroethylene-based polymer is in particulate form.
[5] The composition according to any one of [1] to [4], wherein the inorganic particles have a surface hydroxyl group content of 50/ ^nm2 or less.
[6] The composition according to any one of [1] to [5], wherein the inorganic particles are at least one selected from the group consisting of alumina, cristobalite, boron nitride, magnesium oxide, mica, forsterite, and cordierite.
[7] The composition according to any one of [1] to [6], wherein the inorganic particles have an average particle size of less than 15 μm.
[8] The composition according to any one of [1] to [7], wherein the coupling agent is at least one selected from the group consisting of a benzotriazole functional group-type silane coupling agent and an epoxy functional group-type silane coupling agent.
[9] The composition according to any one of [1] to [8], wherein the content ratio (mass ratio) of the inorganic particles to the tetrafluoroethylene-based polymer is greater than 1.
[10] The composition according to any one of [1] to [9], which is in a liquid or powder form.
[11] A method for producing hydrophobic inorganic particles surface-treated with a coupling agent, which is used in the composition of any one of [1] to [10], comprising shearing the hydrophobic inorganic particles in a solution containing a coupling agent, which is a compound in which a trialkoxysilyl group and a functional group are bonded via a linking group containing one or more bonds selected from an imino bond, an amide bond, a urea bond, a urethane bond, and a carbodiimide bond.
[12] The method for producing inorganic particles according to [11], wherein the shearing treatment is carried out by mixing in a tank equipped with a stirring mechanism using thin film rotation or a stirring mechanism using rotation and revolution.
[13] The method for producing a composition according to any one of [1] to [10], comprising mixing a tetrafluoroethylene-based polymer with hydrophobic inorganic particles obtained by the production method according to [11] or [12] to obtain a composition containing the tetrafluoroethylene-based polymer and the inorganic particles.
[14] A method for producing a laminate, comprising applying the composition according to any one of [1] to [10] to a surface of a substrate, and heating the composition to form a polymer layer containing the tetrafluoroethylene-based polymer and the inorganic particles, thereby obtaining a laminate having a substrate layer made of the substrate and the polymer layer.
[15] A laminate comprising a substrate layer and a polymer layer formed from the composition according to any one of [1] to [10], the polymer layer containing the tetrafluoroethylene-based polymer and the inorganic particles.

The present invention provides a composition containing a tetrafluoroethylene-based polymer and specified inorganic particles, which has excellent dispersion stability and moldability. From such a composition, molded articles can be formed that have low linear expansion coefficients, dielectric constants, and dielectric loss tangents, and that have excellent adhesion to substrates, thermal conductivity, and heat dissipation properties.

The following terms have the following meanings:
The "average particle diameter (D50)" is the volume-based cumulative 50% diameter of particles determined by a laser diffraction/scattering method. That is, the particle size distribution is measured by a laser diffraction/scattering method, a cumulative curve is calculated with the total volume of the particle group set as 100%, and the "average particle diameter (D50)" is the particle diameter at the point on the cumulative curve where the cumulative volume is 50%.
The D50 of particles can be determined by dispersing the particles in water and analyzing them by a laser diffraction/scattering method using a laser diffraction/scattering particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.).
"Melting temperature" is the temperature corresponding to the maximum of the melting peak of a polymer as measured by differential scanning calorimetry (DSC).
The "glass transition temperature (Tg)" is a value measured by analyzing a polymer using dynamic mechanical analysis (DMA) method.
The "viscosity" is determined by measuring the composition using a Brookfield viscometer at 25° C. and 30 rpm. The measurement is repeated three times, and the average value of the three measurements is used.
The "thixotropy ratio" is a value calculated by dividing the viscosity _η1 of the composition measured at a rotation speed of 30 rpm by the viscosity _η2 measured at a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average value of the three measurements is used.
The term "unit" in a polymer refers to an atomic group based on a monomer formed by polymerization of the monomer. The unit may be a unit formed directly by a polymerization reaction, or may be a unit in which a portion of the unit is converted into a different structure by treating the polymer. Hereinafter, a unit based on monomer a may also be simply referred to as a "monomer a unit."

The composition of the present invention (hereinafter also referred to as "the composition") comprises a tetrafluoroethylene-based polymer (hereinafter also referred to as "F polymer") and hydrophobic inorganic particles (hereinafter also referred to as "the inorganic particles") that have been surface-treated with a coupling agent, and the coupling agent is a compound in which a trialkoxysilyl group and a functional group are bonded via a linking group containing one or more bonds selected from the group consisting of an imino bond, an amide bond, a urea bond, a urethane bond, and a carbodiimide bond.

This composition has excellent dispersibility, and it is easy to form molded articles from this composition that possess the high physical properties of the F polymer and inorganic particles, have a low linear expansion coefficient, dielectric constant, and dielectric dissipation factor, and have excellent adhesion to the substrate, thermal conductivity, and heat dissipation properties. The reasons for this are not entirely clear, but are thought to be as follows.

Since F polymers have low surface energy, they tend to aggregate with each other. Furthermore, the affinity between F polymers and inorganic particles is low, making it difficult to obtain a composition in which F particles and inorganic particles are well dispersed. This tendency tends to become more pronounced as the proportion of hydrophobic inorganic particles or inorganic particles contained in the composition increases, making it difficult for the properties of both components to be expressed in the molded product, and also making it easier for adhesion to other substrates to decrease.
The inorganic particles contained in the composition are preferably produced by shearing hydrophobic inorganic particles in a solution containing a specific coupling agent. This method promotes surface roughening of the inorganic particles without impairing the overall properties and physical characteristics of the inorganic particles, and the trialkoxysilyl groups of the specific coupling agent are highly bonded to the roughened inorganic particle surface to form the inorganic particles. In this case, the functional groups of the specific coupling agent are bonded via specific rigid linking groups, and are therefore highly exposed to the surface of the inorganic particles. This not only enhances the affinity between the F polymer and the inorganic particles and improves the dispersibility of the composition, but also promotes the formation of a network structure between the F polymer and the inorganic particles during molding, due to the action of the functional groups of the coupling agent, which is thought to improve the interfacial adhesion between the two components and the adhesion between the molded product and the substrate.
As a result, it is believed that a molded product was obtained from this composition that possesses the physical properties of the F polymer and inorganic particles to a high degree, specifically, a low linear expansion coefficient, dielectric constant, and dielectric dissipation factor, and has excellent adhesion to the substrate, thermal conductivity, and heat dissipation properties.

The F polymer in the present invention is a polymer containing units (hereinafter also referred to as "TFE units") based on tetrafluoroethylene (hereinafter also referred to as "TFE").
The F polymer may be either heat-meltable or non-heat-meltable. Here, a heat-meltable polymer means a polymer at which there exists a temperature at which the melt flow rate is 1 to 1000 g/10 min under a load of 49 N. A non-heat-meltable polymer means a polymer at which there does not exist a temperature at which the melt flow rate is 1 to 1000 g/10 min under a load of 49 N.
The melting temperature of the heat-meltable F polymer is preferably 180°C or higher, more preferably 200°C or higher, and even more preferably 260°C or higher. The melting temperature of the F polymer is preferably 325°C or lower, more preferably 320°C or lower. The melting temperature of the F polymer is preferably 180°C to 320°C. In this case, the composition is likely to have excellent processability, and molded articles formed from the composition are likely to have excellent heat resistance.

The glass transition point of the F polymer is preferably 50° C. or higher, more preferably 75° C. or higher. The glass transition point of the F polymer is preferably 150° C. or lower, more preferably 125° C. or lower.
The fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72 to 76% by mass. Although such an F polymer with a high fluorine content has a low affinity, particularly with inorganic particles, the present invention provides a composition (the present composition) with excellent dispersibility due to the above-mentioned mechanism of action.
The surface tension of the F polymer is preferably 16 to 26 mN/m. The surface tension of the F polymer can be measured by placing a droplet of a mixture for wetting tension testing (manufactured by Wako Pure Chemical Industries, Ltd.) specified in JIS K 6768 on a flat plate made of the F polymer.

F polymer is preferably polytetrafluoroethylene (PTFE), the polymer (ETFE) that comprises TFE unit and the unit based on ethylene, the polymer (EFEP) that comprises TFE unit and the unit based on propylene, the polymer (PFA) that comprises TFE unit and the unit based on perfluoro (alkyl vinyl ether) (PAVE) (PAVE unit), the polymer (FEP) that comprises TFE unit and the unit based on hexafluoropropylene, more preferably PFA and FEP, and more preferably PFA.These polymers can also comprise the unit based on other comonomers.
PAVE is preferably CF ₂ ═CFOCF ₃ , CF ₂ ═CFOCF ₂ CF ₃ or CF ₂ ═CFOCF ₂ CF ₂ CF ₃ (hereinafter also referred to as “PPVE”), with PPVE being more preferred.

The F polymer preferably has an oxygen-containing polar group, more preferably has a hydroxyl-containing group or a carbonyl-containing group, and even more preferably has a carbonyl-containing group.
In this case, the F polymer easily interacts with the inorganic particles, resulting in excellent dispersibility of the composition. Furthermore, the composition can be easily used to obtain molded articles with low linear expansion coefficients, dielectric constants, and dielectric loss tangents, as well as excellent thermal conductivity and adhesiveness.
The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably --CF ₂ CH ₂ OH or --C(CF ₃ ) ₂ OH.
The carbonyl group-containing group is preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH ₂ ), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.), a formyl group, a halogenoformyl group, a urethane group (-NHC(O)O-), a carbamoyl group (-C(O)-NH ₂ ), a ureido group (-NH-C(O)-NH ₂ ), an oxamoyl group (-NH-C(O)-C(O)-NH ₂ ) or a carbonate group (-OC(O)O-), more preferably an acid anhydride residue.
When the F polymer has an oxygen-containing polar group, the number of oxygen-containing polar groups in the F polymer is preferably 10 to 5000, more preferably 100 to 3000, per 1 × ¹⁰ carbon atoms in the main chain. The number of oxygen-containing polar groups in the F polymer can be quantified by the composition of the polymer or the method described in WO 2020/145133.

The oxygen-containing polar group may be contained in a unit derived from a monomer in the F polymer, or may be contained in a terminal group of the main chain of the F polymer, the former being preferred. Examples of the latter include an F polymer having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and an F polymer obtained by subjecting an F polymer to plasma treatment or ionizing radiation treatment.
The monomer having a carbonyl group-containing group is preferably itaconic anhydride, citraconic anhydride, or 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"), and more preferably NAH.

The F polymer is preferably a polymer having a carbonyl group-containing group that contains TFE units and PAVE units, and more preferably a polymer that contains TFE units, PAVE units, and units based on a monomer having a carbonyl group-containing group, in the amounts of 90 to 99 mol%, 0.99 to 9.97 mol%, and 0.01 to 3 mol%, respectively, relative to the total units, in that order. Specific examples of such F polymers include the polymers described in WO 2018/16644.

In the present invention, the F polymer is preferably in the form of particles (hereinafter referred to as "F particles"). The D50 of the F particles is preferably 0.01 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. The D50 of the F particles is preferably less than 10 μm, more preferably less than 8 μm. In this case, the composition is likely to have excellent dispersibility and processability. Furthermore, the composition is likely to produce a molded product having a low linear expansion coefficient, dielectric constant, and dielectric loss tangent, and having excellent adhesion to a substrate, thermal conductivity, and heat dissipation properties.
The specific surface area of the F particles is preferably 1 to 25 m ² /g.

One type of F particles may be used, or two or more types may be used. The F particles are preferably particles of at least a heat-fusible F polymer, and more preferably particles of a heat-fusible F polymer having an oxygen-containing polar group and a melting temperature of 180°C to 320°C. In this case, the dispersibility of the composition is likely to be improved.

When two types of F particles are used, the F particles are preferably a mixture of particles of a heat-fusible F polymer and particles of a non-heat-fusible F polymer. In this case, the aggregation-inhibiting effect of the heat-fusible F polymer particles and the retention effect of the non-heat-fusible F polymer due to fibrillation are balanced, and the dispersibility of the composition is likely to be improved. In addition, the electrical properties of the non-heat-fusible F polymer are highly expressed in the molded product obtained therefrom, and molded products with particularly low dielectric loss tangents are likely to be obtained.
The former particles are preferably particles of a heat-fusible F polymer having a melting temperature of 200 to 320° C., and more preferably particles of a heat-fusible F polymer having an oxygen-containing polar group and a melting temperature of 180 to 320° C. In the former particles, the preferred embodiments of the heat-fusible F polymer having an oxygen-containing polar group are the same as the preferred embodiments of the F polymer having an oxygen-containing polar group described above.
As the latter particles, particles of non-thermofusible PTFE are preferred.
The proportion of the former particles in the total mass of the two types of F particles is preferably 50% by mass or less, more preferably 40% by mass or less, and is preferably 5% by mass or more, more preferably 10% by mass or more.
It is also preferable that the former particles have a D50 of 1 to 4 μm, and the latter particles have a D50 of 0.1 to 1 μm.

The F particles may contain a resin or an inorganic compound other than the F polymer, may form a core-shell structure with an F polymer as the core and a resin other than the F polymer or an inorganic compound as the shell, or may form a core-shell structure with an F polymer as the shell and a resin other than the F polymer or an inorganic compound as the core.
Here, examples of resins other than the F polymer include aromatic polyesters, polyamideimides, polyimides, and maleimides, and examples of inorganic compounds include silica and boron nitride.

The hydrophobic inorganic particles used in the present invention preferably have a surface hydroxyl group density of 100 or ^less per square meter, more preferably 50 or less per square ^meter .
The amount of surface hydroxyl groups per unit amount of inorganic particles is measured by the following method.
1.5 g of inorganic particles are weighed out and adjusted to a pH of approximately 3 with 0.1 mol/L hydrochloric acid, and then diluted with distilled water to a total weight of 150 g. 0.1 mol/L sodium hydroxide is added dropwise to this prepared solution to determine the amount required to reach a pH of 9. This is substituted into the following formula (1) to calculate the amount of surface hydroxyl groups.
Amount of surface hydroxyl groups (number/nm ² )=[amount of sodium hydroxide at 0.1 mol/L×6×10 ²³ ]/[amount of inorganic particles×specific surface area] (Equation (1))

The shape of the hydrophobic inorganic particles may be spherical, acicular (fibrous), or plate-like. Specifically, they may be spherical, scale-like, layered, leaf-like, apricot-like, columnar, cockscomb-like, equiaxed, leaf-like, mica-like, block-like, flat, wedge-like, rosette-like, mesh-like, or prismatic, with scale-like shapes being preferred. In this case, the inorganic particles are likely to form heat conduction paths in a molded product formed from the composition, and the molded product is likely to have excellent thermal conductivity and low linear expansion.

Examples of inorganic compounds in the hydrophobic inorganic particles include carbon, inorganic nitrides, and inorganic oxides. Examples include carbon fiber, glass, boron nitride, silicon nitride, aluminum nitride, beryllia, silica, cristobalite, alumina (aluminum oxide), wollastonite, mica, talc, cerium oxide, magnesium oxide, zinc oxide, forsterite (2MgO.SiO ₂ ), cordierite (2MgO.2Al _{2 O} 3.5SiO ₂ ), and titanium oxide. Among these, from the viewpoints of the dispersion stability of the composition and the thermal conductivity and heat dissipation properties of a molded article formed from the composition, at least one selected from the group consisting of alumina, cristobalite, boron nitride, magnesium oxide, mica, forsterite, and cordierite is preferred, boron nitride is more preferred, and hexagonal boron nitride is even more preferred.
Specific examples of boron nitride particles include the "UHP" series (manufactured by Showa Denko KK) and the "GP" and "HGP" grades of the "Denka Boron Nitride" series (manufactured by Denka Company Limited).
The hydrophobic inorganic particles may be used alone or in combination of two or more kinds.

When the hydrophobic inorganic particles are scaly hexagonal boron nitride particles, it is believed that they are more likely to form a house-of-cards structure in the composition and in molded articles formed from the composition, forming a heat conduction path. As a result, the composition has excellent dispersibility, and molded articles tend to have excellent low linear expansion, thermal conductivity, and heat dissipation properties, which is preferable.

The average particle size (D50) of the hydrophobic inorganic particles is preferably less than 15 μm, more preferably less than 10 μm, and more preferably 8 μm or less. The D50 of the hydrophobic inorganic particles is preferably 0.1 μm or more, more preferably 1 μm or more. Such hydrophobic inorganic particles with a small D50 tend to aggregate easily and have low affinity with the F polymer, but due to the above-mentioned mechanism of action, a composition (the present composition) with excellent dispersibility can be obtained according to the present invention.
The aspect ratio of the hydrophobic inorganic particles is preferably 1 or more, more preferably 10 or more, and is preferably 10,000 or less.

The present inorganic particles are surface-treated with a coupling agent (hereinafter also referred to as "the present coupling agent"), which is a compound in which a trialkoxysilyl group and a functional group are bonded via a linking group containing at least one bond selected from the group consisting of an imino bond, an amide bond, a urea bond, a urethane bond, and a carbodiimide bond.
Examples of the trialkoxysilyl group in the present coupling agent include a trimethoxysilyl group and a triethoxysilyl group.
Examples of the functional group in the present coupling agent include a triazine group, an isocyanate group, an isocyanuric acid group, a benzotriazole group, an acid anhydride group, an azasilacyclopentane group, an imidazole group, an epoxy group, a (meth)acrylic group, a (meth)acryloyloxy group, an alkenyl group, and a styryl group. Among these, a benzotriazole group or an epoxy group is preferred. The present coupling agent may have a plurality of different types of functional groups or a plurality of the same type of functional groups.
The linking group may be, for example, a group having a divalent organic group (such as an alkylene group or an alkylene group having an etheric oxygen atom between carbon atoms) as the main chain and including one or more bonds selected from an imino bond, an amide bond, a urea bond, a urethane bond, and a carbodiimide bond.

The coupling agent can be a compound having the above-mentioned functional group and trimethoxysilyl group, respectively, at both ends of a main chain containing the linking group; a compound having multiple functional groups in a main chain containing the linking group and multiple triethoxysilyl groups in side chains; a compound having a siloxane structure in a main chain containing the linking group and functional groups at both ends of the main chain; a compound having a butadiene structure in a main chain containing the linking group and one acid anhydride group and one trimethoxysilyl group in a side chain; or a compound having an alkoxysiloxane structure in a main chain containing the linking group and multiple epoxy groups in side chains.

Specific examples of this coupling agent include 3-isocyanatepropyltriethoxysilane, 3-ureidopropyltriethoxysilane, tris(trimethoxysilylpropyl)isocyanurate, tris(triethylsilylpropyl)isocyanurate, 1-(3-(trimethoxysilyl)propyl)-3,5-di-2-propenyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3-(trimethoxysilyl)propyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-[5-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, N-[5-(triethoxysilyl)-2-aza-1-oxopentyl]caprolactam, N-[3-(triethoxysilyl)propyl]-2-aza-1-oxopentyl]caprolactam, N-[3-(triethoxysilyl)propyl]-carbamic acid ethyl ester, N-[3-(trimethoxysilyl)propyl]-carbamic acid ethyl ester, 3,5-dimethyl-N-[3-(trimethoxysilyl)propyl]-1H-pyrazole-1-carboxamide, 3,5-dimethyl-N-[3-(triethoxysilyl)propyl]-1H-pyrazole-1-carboxamide, 2-[3-(trimethoxysilyl)propyl]succinate Acid anhydride, 2-[3-(triethoxysilyl)propyl]succinic anhydride, N-(trimethoxysilylpropyl)-1H-benzotriazole-1-carbodiamide, dihydro-3-(trimethoxysilylpropyl)-2,5-furandione, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, N-2-pyridinyl-N-(triethoxysilylpropyl)-urea, 3-[(trimethoxysilyl)propyl]-1H-imidazole, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, β-(3, Examples include 4-epoxycyclohexyl)ethyltrimethoxysilane, epoxy group-containing oligomer silane coupling agents, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, p-styryltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

Among these, the functional group in the present coupling agent is more preferably a benzotriazole group or an epoxy group, i.e., the present coupling agent is more preferably at least one selected from a benzotriazole functional group-type silane coupling agent and an epoxy functional group-type silane coupling agent.
Commercially available coupling agents such as these can also be used, and examples thereof include "X-12-1214A,""X-12-981S,""X-12-984S,""KBM-303,""KBM-402,""KBE-402,""KBM-403,""KBE-403,""X-12-967C,""KBM-1403," and "KBM-4803" (all trade names) manufactured by Shin-Etsu Chemical Co., Ltd.

As a method for producing the present inorganic particles by surface-treating hydrophobic inorganic particles with the present coupling agent, a method of mixing a solution containing the present coupling agent with the hydrophobic inorganic particles can be mentioned. In particular, as a method for producing the present inorganic particles, it is preferable to shear the hydrophobic inorganic particles in a solution containing the present coupling agent. It is believed that this method can form the present inorganic particles through the above-mentioned mechanism of action, and enhance the affinity with the F polymer.
The shearing treatment is preferably carried out by mixing in a vessel equipped with a stirring mechanism that uses thin film rotation or a stirring mechanism that uses rotation and revolution.
An example of a vessel equipped with the above-mentioned thin film swirl stirring mechanism is a thin film swirl high-speed mixer, which is a stirring device that spreads hydrophobic inorganic particles and a solution containing the present coupling agent in the form of a thin film on the inner wall surface of a cylindrical stirring vessel, swirls the mixture, and mixes them while applying centrifugal force.
Examples of vessels equipped with a rotational and revolutional stirring mechanism include a planetary mixer and a planetary-revolution mixer. A planetary mixer is a stirring device having two stirring blades that rotate and revolve around each other.
In the shear treatment, the reaction of the coupling agent may be promoted by heating the mixture of the solution containing the coupling agent and the hydrophobic inorganic particles, preferably under reflux conditions. The reaction of the coupling agent may also be accelerated by using a reaction catalyst.

The solvent for the solution containing the coupling agent is preferably an alcohol, such as methanol, ethanol, isopropanol, or butanol, which has a boiling point at atmospheric pressure in the range of 50°C to 200°C, and more preferably methanol or ethanol.
The solvent is removed from the solution after shearing, and further dried as necessary to obtain the inorganic particles. Removal of the solvent from the solution can be achieved by known methods such as filtration or centrifugation. Drying can be carried out using known drying means such as an oven or a forced-air drying furnace, for example, at a temperature above the boiling point of the solvent for 10 to 300 minutes. Drying can be carried out under atmospheric pressure or reduced pressure, and may be carried out in air or an inert gas atmosphere such as helium gas, neon gas, argon gas, or nitrogen gas.
After drying, the hydrophobic inorganic particles that have been surface-treated with the present coupling agent may be crushed to obtain the present inorganic particles, or may be classified to obtain the present inorganic particles.

The content of F particles in the composition is preferably 10% by mass or more, more preferably 20% by mass or more, and is preferably 50% by mass or less.
The content of the inorganic particles in the composition is preferably 10% by mass or more, more preferably 20% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less.
In the present composition, the ratio (mass ratio) of the content of the present inorganic particles to the content of the F particles is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably more than 1. The ratio is preferably 3 or less, more preferably 2 or less.
When the content and content ratio of the F particles and the present inorganic particles are within the above ranges, the present composition is likely to have excellent dispersibility due to the above-mentioned mechanism of action, and the present composition is also likely to produce a molded product that has a low linear expansion coefficient, dielectric constant, and dielectric dissipation factor, and that has excellent adhesion to substrates, thermal conductivity, and heat dissipation properties.

The present composition may further contain other inorganic particles different from the present inorganic particles, as long as the effects of the present invention are not impaired. The other inorganic particles may be spherical, acicular, fibrous, or plate-like in shape. Examples of other inorganic particles include carbon fiber, glass, boron nitride, aluminum nitride, beryllia, silica, wollastonite, talc, cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, and titanium oxide.
When the present composition further contains inorganic particles other than the present inorganic particles, the content thereof is preferably 1 to 20% by mass or less based on the total mass of the composition.

The present composition may further contain another resin different from the tetrafluoroethylene-based polymer. Such another resin may be contained in the present composition as particles, or, when the present composition contains a liquid dispersion medium described below, may be contained in the form of a solution or dispersion in the liquid dispersion medium.
Examples of other resins include polyester resins such as liquid crystalline aromatic polyesters, polyimide resins, polyamideimide resins, epoxy resins, maleimide resins, urethane resins, polyphenylene ether resins, polyphenylene oxide resins, and polyphenylene sulfide resins.
The other resin is preferably an aromatic polymer, more preferably at least one aromatic imide polymer selected from the group consisting of aromatic polyimide, aromatic polyamic acid, aromatic polyamideimide, and a precursor of aromatic polyamideimide. The aromatic polymer is preferably contained in the composition as a varnish dissolved in a liquid dispersion medium.
When the present composition further contains other resins, the content thereof is preferably 0.1 to 5% by mass based on the total mass of the composition.

The present composition may be in the form of a powder, a liquid further containing a liquid dispersion medium (such as a dispersion or a slurry), or a dough. Alternatively, the present composition in powder form may be melted to form the present composition in pellet form.
The liquid dispersion medium is preferably a compound that is liquid at 25°C under atmospheric pressure and has a boiling point of 50 to 240°C. One type of liquid dispersion medium may be used, or two or more types may be used. When two types of liquid dispersion medium are used, the two types of liquid dispersion medium are preferably compatible with each other.

The liquid dispersion medium is preferably a compound selected from the group consisting of water, amides, ketones and esters.
Examples of the amide include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropanamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-diethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone.
Examples of the ketone include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, 2-heptanone, cyclopentanone, cyclohexanone, and cycloheptanone.
Examples of the ester include methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl 3-ethoxypropionate, γ-butyrolactone, and γ-valerolactone.

When the present composition contains a liquid dispersion medium, the content of the liquid dispersion medium is preferably 10 to 70% by mass or more based on the total amount of the present composition.
When the composition contains a liquid dispersion medium, the solids concentration in the composition is preferably 30% by mass or more, more preferably 40% by mass or more, and is preferably 90% by mass or less, more preferably 60% by mass or less.
The solid content refers to the total amount of substances that form the solid content in a molded product formed from the composition. Specifically, the F particles and the inorganic particles are solid content, and when the composition contains other resins or other inorganic particles, these other resins or other inorganic particles are also solid content, and the total mass proportion of these components is the solid content concentration in the composition.

When the present composition contains a liquid dispersion medium, the present composition preferably further contains a surfactant, preferably a nonionic surfactant, from the viewpoint of improving dispersion stability.
Specific examples of nonionic surfactants include the "Ftergent" series (manufactured by Neos Corporation), the "Surflon" series (manufactured by AGC Seimi Chemical Co., Ltd.), the "Megafac" series (manufactured by DIC Corporation), the "Unidyne" series (manufactured by Daikin Industries, Ltd.), "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", and "BYK-3456" (manufactured by BYK Japan KK), "KF-6011", and "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), and the "Tergitol" series (manufactured by The Dow Chemical Company, "Tergitol TMN-100X", etc.).
When the present composition contains a nonionic surfactant, the content of the nonionic surfactant in the present composition is preferably 0.1 to 10% by mass based on the total mass of the present composition.

If necessary, the composition may further contain a silane coupling agent. Examples of silane coupling agents include those similar to those that may be used for surface treatment of hydrophobic inorganic particles. When the composition contains a silane coupling agent, the content of the silane coupling agent in the composition is preferably 0.1 to 10% by mass based on the total mass of the composition.

The composition may further contain additives such as a thixotropic agent, viscosity modifier, antifoaming agent, dehydrating agent, plasticizer, weathering agent, antioxidant, heat stabilizer, lubricant, antistatic agent, brightener, colorant, conductive agent, mold release agent, surface treatment agent other than the above-mentioned silane coupling agent, and flame retardant.

When the composition contains a liquid dispersion medium, the viscosity of the composition is preferably 10 mPa·s or more, more preferably 100 mPa·s or more, and is preferably 10,000 mPa·s or less, more preferably 3,000 mPa·s or less.
When the present composition contains a liquid dispersion medium and is in a liquid state, the thixotropy ratio thereof is preferably 1.0 to 3.0.
When the present composition contains water as a liquid dispersion medium, from the viewpoint of improving long-term storage stability, the pH is more preferably 8 to 10. The pH of the present composition can be adjusted with a pH adjuster (amine, ammonia, citric acid, etc.) or a pH buffer (tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium hydrogencarbonate, ammonium carbonate, ammonium acetate, etc.).

The present composition can be obtained by mixing the F particles and the present inorganic particles, and, if necessary, other resins, other inorganic particles, a liquid dispersion medium, a surfactant, a silane coupling agent, additives, and the like.
The composition may be obtained by mixing the F particles and the inorganic particles all at once, or by mixing them separately and sequentially, or by preparing a master batch of these and then mixing the remaining components with it. The order of mixing is not particularly limited, and the mixing method may be either all at once or divided into multiple batches.
Examples of mixing devices for obtaining the present composition include agitators equipped with blades, such as a Henschel mixer, pressure kneader, Banbury mixer, and planetary mixer; grinding devices equipped with media, such as a ball mill, attritor, basket mill, sand mill, sand grinder, Dyno Mill, Dispermat, SC mill, spike mill, and agitator mill; and dispersing devices equipped with other mechanisms, such as a microfluidizer, nanomizer, ultimizer, ultrasonic homogenizer, dissolver, disper, high-speed impeller, thin film swirling high-speed mixer, planetary mixer, and V-type mixer.

A suitable method for producing the present composition containing a liquid dispersion medium is to pre-knead the F particles, the present inorganic particles, and a portion of the liquid dispersion medium to obtain a kneaded mixture, and then add the kneaded mixture to the remaining liquid dispersion medium to obtain the present composition. The liquid dispersion medium used during kneading and addition may be the same or different liquid dispersion mediums. Other resins, other inorganic particles, surfactants, silane coupling agents, and additives may be mixed during kneading or addition. Mixing during kneading is preferably performed using a planetary mixer or a planetary-rotating/revolving mixer.

The kneaded product obtained by kneading may be in a paste form (e.g., a paste having a viscosity of 1000 to 100,000 mPa s), or in a wet powder form (e.g., a wet powder (kneaded powder) having a viscosity measured by a capillograph of 10,000 to 100,000 Pa s).
The viscosity measured by capillography is a value measured using a capillary having a capillary length of 10 mm and a capillary radius of 1 mm, with a furnace diameter of 9.55 mm, a load cell capacity of 2 t, a temperature of 25°C, and a shear rate of 1 s ^-1 .

When the composition is subjected to a molding method such as extrusion, a molded product such as a sheet can be obtained.
When the composition contains a liquid dispersion medium and is in a liquid state, it is preferable to extrude the composition into a sheet. The extruded sheet may be further cast by press molding, calendar molding, etc. The sheet is preferably further heated to remove the liquid dispersion medium and bake the F polymer.
When the composition is in powder form, it is preferable to melt-extrude the composition, which can be carried out using a single-screw extruder, a multi-screw extruder, or the like.
The composition may also be injection molded to obtain a molded article.
When forming a molded product, the present composition may be directly melt extruded or injection molded, or the present composition may be melt kneaded to form pellets, and the pellets may be melt extruded or injection molded to obtain a molded product such as a sheet.

The thickness of the sheet obtained from the composition is preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 25 μm or more, and is preferably 200 μm or less, more preferably 100 μm or less.
The linear expansion coefficient of the sheet is preferably 100 ppm/° C. or less, more preferably 80 ppm/° C. or less. The lower limit of the linear expansion coefficient of the sheet is 30 ppm/° C. The linear expansion coefficient means the value measured for a test piece in the range of 25° C. or more and 260° C. or less according to the measurement method specified in JIS C 6471:1995.
The thermal conductivity of the sheet in the in-plane direction is preferably 1.0 W/m·K or more, more preferably 3.0 W/m·K or more. The upper limit of the sheet thermal conductivity is 20 W/m·K.

The laminate can be formed by laminating the sheet on a substrate. Examples of methods for producing the laminate include a method using a co-extruder as the extruder to extrude the composition together with the raw materials for the substrate, a method of extruding the composition onto the substrate, and a method of thermocompression bonding the sheet and the substrate.
Examples of the substrate include metal substrates (metal foils such as copper, nickel, aluminum, titanium, and alloys thereof), heat-resistant resin films (heat-resistant resin films such as polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyaryl ether ketone, polyamideimide, liquid crystalline polyester, and tetrafluoroethylene-based polymers), prepreg substrates (precursors of fiber-reinforced resin substrates), ceramic substrates (ceramic substrates such as silicon carbide, aluminum nitride, and silicon nitride), and glass substrates.

The shape of the substrate may be flat, curved, or uneven, and may be any of foil, plate, film, and fiber.
The ten-point average roughness of the surface of the substrate is preferably 0.01 to 0.05 μm.
The surface of the substrate may be surface-treated with a silane coupling agent or may be plasma-treated. Preferred examples of such silane coupling agents include silane coupling agents having a functional group, such as 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-isocyanatopropyltriethoxysilane.
The peel strength between the sheet and the substrate is preferably 2 kN/m or more, more preferably 2.5 kN/m or more, and is preferably 10 kN/m or less.

By disposing the present composition on the surface of a substrate and forming a polymer layer containing the F polymer and the present inorganic particles, a laminate having a substrate layer made of the substrate and a polymer layer can be obtained.
The polymer layer is preferably formed by placing the composition containing a liquid dispersion medium on the surface of a substrate, heating to remove the dispersion medium, and further heating to bake the F polymer.
Examples of the substrate include the same substrates as those that can be laminated with the above-mentioned sheet, and the preferred embodiments thereof are also the same.

The composition can be applied by coating, droplet discharging, or immersion, preferably by roll coating, knife coating, bar coating, die coating, or spraying.
The heating for removing the liquid dispersion medium is preferably carried out at 100 to 200°C for 0.1 to 30 minutes. The liquid dispersion medium does not need to be completely removed during heating; it is sufficient to remove it to the extent that the layer formed by packing the F particles and the present inorganic particles can maintain a self-supporting film. Furthermore, during heating, air may be blown onto the surface to promote removal of the liquid dispersion medium by air drying.
The heating for baking the F polymer is preferably carried out at a temperature equal to or higher than the baking temperature of the F polymer, more preferably at 360 to 400° C. for 0.1 to 30 minutes.
Heating devices for each heating method include ovens and ventilation drying furnaces. The heat source in the device may be a contact type heat source (hot air, hot plate, etc.) or a non-contact type heat source (infrared rays, etc.).
The heating may be carried out under normal pressure or under reduced pressure.
The atmosphere during each heating step may be either an air atmosphere or an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.).

The polymer layer is formed through the steps of disposing the composition and heating. These steps may be performed once each, or may be repeated two or more times. For example, the composition may be disposed on the surface of a substrate and heated to form a polymer layer, and then the composition may be disposed on the surface of the polymer layer and heated to form a second polymer layer. Alternatively, the composition may be disposed on the surface of a substrate and heated to remove the liquid dispersion medium, and then the composition may be disposed on the surface of the substrate and heated to form a polymer layer.
The composition may be disposed on only one surface of a substrate, or on both surfaces of the substrate, in the former case, resulting in a laminate having a substrate layer and a polymer layer on one surface of the substrate layer, and in the latter case, resulting in a laminate having a substrate layer and polymer layers on both surfaces of the substrate layer.

Suitable specific examples of the laminate include a metal clad laminate having a metal foil and a polymer layer on at least one surface of the metal foil, and a multilayer film having a polyimide film and polymer layers on both surfaces of the polyimide film.
The preferred ranges of the thickness, dielectric constant, dielectric dissipation factor, linear expansion coefficient, thermal conductivity in the in-plane direction, and peel strength between the polymer layer and the substrate layer are the same as the preferred ranges of the thickness, dielectric constant, dielectric dissipation factor, linear expansion coefficient, thermal conductivity in the in-plane direction, and peel strength between the sheet and the substrate for the sheet obtained from the composition described above.

The composition is useful as a material for imparting insulating properties, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, and thermal conductivity.
Specifically, the composition can be used in printed wiring boards, thermal interface materials, power module substrates, coils used in power devices such as motors, automotive engines, heat exchangers, vials, syringes, ampoules, medical wires, secondary batteries such as lithium ion batteries, primary batteries such as lithium batteries, radical batteries, solar cells, fuel cells, lithium ion capacitors, hybrid capacitors, capacitors (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode binders, electrode separators, and electrodes (positive electrodes, negative electrodes).
The composition is also useful as an adhesive for bonding parts. Specifically, the composition can be used for bonding ceramic parts, metal parts, electronic parts such as IC chips, resistors, and capacitors on substrates for semiconductor devices and module parts, bonding circuit boards and heat sinks, and bonding LED chips to substrates.
The composition can also be used in applications requiring electrical conductivity, such as in the field of printed electronics, for example, in the manufacture of conductive elements in printed circuit boards, sensor electrodes, and the like.

Molded articles, sheets and laminates formed from the present composition are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sporting goods, food industry products, heat dissipation parts, paints, cosmetics and the like.
Specifically, these include electric wire coating materials (aircraft electric wires, etc.), enameled wire coating materials used in motors for electric vehicles, etc., electrical insulating tape, insulating tape for oil drilling, oil transport hoses, hydrogen tanks, materials for printed circuit boards, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), copy rolls, furniture, automobile dashboards, covers for home appliances, etc., sliding components (load bearings, yaw bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear rings, etc.), and many other applications. useful for: pins, pistons, slide switches, gears, cams, belt conveyors, food transport belts, etc.), tension ropes, wear pads, wear strips, tube lamps, test sockets, wafer guides, wear parts of centrifugal pumps, chemical and water supply pumps, tools (shovels, files, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, racket strings, dies, toilets, container coating materials, heat dissipation substrates for mounting power devices, heat dissipation components for wireless communication devices, transistors, thyristors, rectifiers, transformers, power MOS FETs, CPUs, heat dissipation fins, metal heat sinks, blades for wind turbines, wind power generation equipment, aircraft, etc., housings for personal computers and displays, electronic device materials, interior and exterior parts of automobiles, sealing materials for processing machines and vacuum ovens that perform heat treatment under low oxygen conditions, plasma processing equipment, etc., heat dissipation components in processing units for sputtering and various dry etching equipment, etc., and electromagnetic wave shielding.

Molded articles, sheets, and laminates formed from the present composition are particularly useful as heat dissipation sheets or heat dissipation substrates for electronic substrate materials such as flexible printed wiring boards and rigid printed wiring boards for car electronics, such as LED headlamps, power control units, and electric control units, and as heat dissipation substrates for automobiles.
When using a molded article, sheet, or laminate formed from the present composition as a heat dissipation component, the molded article, sheet, or laminate may be directly attached to the target substrate, or may be attached to the target substrate via an adhesive layer such as a silicone-based adhesive layer.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
1. Preparation of each component [F Polymer]
F Particles 1: Particles (D50: 2.1 μm, non-hollow) of a tetrafluoroethylene polymer (melting temperature: 300° C.) containing 97.9 mol%, 0.1 mol%, and 2.0 mol% of TFE units, NAH units, and PPVE units, in that order, and having 1,000 carbonyl group-containing groups per 1 × ¹⁰ carbon atoms in the main chain.
[Hydrophobic inorganic particles]
Inorganic particles 1: plate-shaped boron nitride particles (hexagonal system, average particle size (D50) 11 μm)
[Coupling Agent]
Coupling agent 1: "X-12-1214A" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., N-(trimethoxysilyl-propyl)-1H-benzotriazole-1-carbodiamide; a compound in which a trimethoxysilyl group and a benzotriazole group are bonded via a linking group containing a carbodiimide bond)
Coupling agent 2: "X-12-984S" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., a compound in which a triethoxysilyl group and a glycidyl ether group are bonded via a linking group containing a urethane bond)
Coupling agent 3: "KBM-904" (product name, manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycoxidepropyltrimethoxysilane)
[Liquid dispersion medium]
NMP: N-methyl-2-pyrrolidone

2. Example of composition production [Example 1]
The methanol solution containing coupling agent 1 and inorganic particles 1 were sheared for 5 hours using a planetary mixer while being heated to reflux at 80° C. The contents were filtered, and the residue was dried to obtain inorganic particles 1 surface-treated with coupling agent 1 (hereinafter referred to as "BN-T ₁₁ ").
The BN-T ₁₁ (22 parts by mass), F particles 1 (11 parts by mass), and NMP (20 parts by mass) obtained above were kneaded in a planetary centrifugal mixer to obtain a wet powder-like dough 1, and NMP (47 parts by mass) was further added and stirred to obtain a dispersion liquid, Composition 1.

[Example 2]
Inorganic particles 1 (hereinafter referred to as "BN-T 21") surface-treated with coupling agent 2 were obtained in the same manner as in Example 1, except that the methanol solution containing coupling agent 1 was changed to a methanol solution containing coupling agent 2. Further, composition 2, which was a dispersion containing BN-T ₂₁ , F particles ₁ , and NMP, was obtained in the same manner as in Example 1.
[Example 3]
Inorganic particles 1 (hereinafter referred to as "BN-T 31") surface-treated with coupling agent 3 were obtained in the same manner as in Example 1, except that the methanol solution containing coupling agent 1 was changed to a methanol solution containing coupling agent 3. Further, composition 3, which was a dispersion containing BN-T ₃₁ , F particles 1, and NMP _, was obtained in the same manner as in Example 1.

[Example 4]
Inorganic particles 1 (22 parts by mass), F particles 1 (11 parts by mass), and NMP (20 parts by mass) were kneaded in a planetary centrifugal mixer to obtain a wet powder-like dough, and NMP (47 parts by mass) was further added and stirred to obtain composition 4, which was a dispersion.
[Example 5]
F particles 1 (15 parts by mass) and NMP (25 parts by mass) were kneaded in a planetary centrifugal mixer to obtain a wet powder-like dough, and NMP (60 parts by mass) was further added and stirred to obtain composition 5, which was a dispersion liquid.

3. Evaluation of Dispersion Stability of Composition After each composition was stored in a container at 25° C., its dispersibility was visually confirmed and the dispersion stability was evaluated according to the following criteria.
[Evaluation criteria]
◯: No aggregates are visible.
Δ: Aggregates were visible at the bottom of the container, but were easily redispersed.
x: Aggregates were visually observed to have settled at the bottom of the container, making redispersion difficult.
In addition, for Composition 3, the production and evaluation of the laminate described below were not carried out from the viewpoint of its dispersion stability.

4. Laminate Production Example Composition 1 was applied to the surface of a long copper foil using a bar coater to form a wet film. The copper foil on which this wet film was formed was then passed through a drying oven at 110°C for 5 minutes to dry it, forming a dry film. The copper foil with the dry film was then heated in a nitrogen oven at 380°C for 3 minutes. This produced a laminate 1 having copper foil and, on its surface, a 50 μm-thick polymer layer containing a fused-and-fired product of F particles 1 and BN-T ₁₁ .
Laminates 2, 4 and 5 were produced from compositions 2, 4 and 5 in the same manner as for Laminate 1.

5. Evaluation of Laminates 5-1. Evaluation of Thermal Conductivity of Laminates For each laminate, the copper foil of the laminate was removed by etching with an aqueous ferric chloride solution to prepare a sheet of a single polymer layer. A 10 mm x 10 mm square test piece was cut from the center of the prepared sheet, and the thermal conductivity (W/m K) in the in-plane direction was measured and evaluated according to the following criteria.
[Evaluation criteria]
〇: More than 2W/m・K △: More than 1W/m・K and less than 2W/m・K ×: Less than 1W/m・K

5-2. Evaluation of peel strength of laminates A rectangular test piece (100 mm long, 10 mm wide) was cut out from each laminate. The test piece was fixed at a position 50 mm from one end in the longitudinal direction, and the copper foil and polymer layer were peeled off from one end in the longitudinal direction at an angle of 90° to the test piece at a pulling rate of 50 mm/min.
The maximum load applied at this time was measured as the peel strength (N/m) and evaluated according to the following criteria.
[Evaluation criteria]
◯: 2 kN/m or more ×: less than 2 kN/m The above results are shown in Table 1.

As is clear from the above results, the composition has excellent dispersion stability, and the laminate formed from the composition highly expresses the physical properties of the F polymer and inorganic particles, and has excellent adhesion to the substrate, thermal conductivity, and heat dissipation properties.

Claims (14)

A composition comprising a tetrafluoroethylene-based polymer and hydrophobic inorganic particles surface-treated with a coupling agent, wherein the coupling agent is a compound in which a trialkoxysilyl group and a functional group are bonded via a linking group containing at least one bond selected from the group consisting of an imino bond, an amide bond, a urea bond, a urethane bond, and a carbodiimide bond, and the functional group is a benzotriazole group or an epoxy group . The composition according to claim 1, wherein the tetrafluoroethylene-based polymer is a heat-melting tetrafluoroethylene-based polymer having a melting temperature of 180°C or higher. The composition according to claim 1 or 2, wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having an oxygen-containing polar group. The composition according to any one of claims 1 to 3, wherein the tetrafluoroethylene-based polymer is in particulate form. The composition according to any one of claims 1 to 4, wherein the inorganic particles have a surface hydroxyl group content of 50/nm2 or ^less . The composition according to any one of claims 1 to 5, wherein the inorganic particles are at least one selected from the group consisting of alumina, cristobalite, boron nitride, magnesium oxide, mica, forsterite, and cordierite. The composition described in any one of claims 1 to 6, wherein the inorganic particles have an average particle size of less than 15 μm. The composition described in any one of claims 1 to 7, wherein the content ratio (mass ratio) of the inorganic particles to the tetrafluoroethylene-based polymer is greater than 1. The composition according to any one of claims 1 to 8, which is in liquid or powder form. 10. A method for producing hydrophobic inorganic particles surface-treated with a coupling agent, which is used in the composition according to any one of claims 1 to 9, comprising shearing hydrophobic inorganic particles in a solution containing a coupling agent in which a trialkoxysilyl group and a functional group are bonded via a linking group containing at least one selected from the group consisting of an imino bond , an amide bond, a urea bond, a urethane bond, and a carbodiimide bond, and the functional group is at least one selected from the group consisting of a benzotriazole group and an epoxy group. The method for producing inorganic particles described in claim 10, wherein the shearing treatment is carried out by mixing in a tank equipped with a stirring mechanism that uses thin film rotation or a stirring mechanism that uses rotation and revolution. A method for producing the composition described in any one of claims 1 to 9, comprising mixing a tetrafluoroethylene-based polymer with hydrophobic inorganic particles obtained by the production method of claim 10 or 11 to obtain a composition containing the tetrafluoroethylene-based polymer and the inorganic particles. A method for producing a laminate, comprising applying the composition described in any one of claims 1 to 9 to the surface of a substrate, heating the composition to form a polymer layer containing the tetrafluoroethylene-based polymer and the inorganic particles, and obtaining a laminate having a substrate layer made of the substrate and the polymer layer. A laminate having a substrate layer and a polymer layer formed from the composition described in any one of claims 1 to 9, the polymer layer containing the tetrafluoroethylene-based polymer and the inorganic particles.