Composition

Abstract

The present invention provides a composition that contains, in prescribed ranges, tetrafluoroethylene-based polymer particles and spheroidal and non-spheroidal boron nitride particles having a prescribed average particle diameter, that has excellent dispersibility, and that makes it possible to form a molded article which has low linear expansion coefficient, low dielectric constant, and low dielectric loss tangent, and which has excellent thermal conductivity, excellent bending tolerance, and excellent adhesiveness.　Provided is a composition comprising: tetrafluoroethylene-based polymer particles; spheroidal boron nitride particles that have an average particle diameter of 5-40 μm; and non-spheroidal boron nitride particles that have an average particle diameter of less than 15 μm, wherein the mass ratio of the non-spheroidal boron nitride particles with respect to the total mass of the spheroidal boron nitride particles and the non-spheroidal boron nitride particles is less than 30%.

Description

Technical Field

[0001] The present invention relates to a predetermined composition containing particles of a tetrafluoroethylene-based polymer, spherical boron nitride particles, and non-spherical boron nitride particles.

Background Art

[0002] In recent years, in order to cope with the high speed and high frequency of mobile communication devices such as mobile phones, materials for printed circuit boards of communication devices are required to have high thermal conductivity, low linear expansion coefficient, low dielectric constant and low dielectric tangent. Tetrafluoroethylene-based polymers having a low dielectric constant and a low dielectric tangent have attracted attention. In order to obtain a material with more excellent physical properties, compositions of tetrafluoroethylene-based polymers and other components have been studied. In Patent Document 1, a powder composition of particles of a tetrafluoroethylene-based polymer and particles of boron nitride having two different particle sizes has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Tetrafluoroethylene-based polymers have low surface tension and low affinity with other components. Therefore, in a molded product formed from a composition in which other components are inorganic particles such as boron nitride particles, the physical properties of each component may not be fully exhibited. The present inventors have found that in the composition of Patent Document 1 described above, the melt viscosity is high during melt mixing, making it difficult to improve the dispersibility of boron nitride particles. Therefore, it is difficult to obtain a composition that can form a molded product such as a sheet that has electrical characteristics and thermal conductivity and is excellent in bend resistance and adhesion (peel strength) to a base material. The present inventors have discovered that a composition containing tetrafluoroethylene polymer particles and spherical and non-spherical boron nitride particles having a predetermined average particle size within a predetermined range exhibits excellent dispersibility even with a small average particle size, and that molded articles have low coefficient of linear expansion, dielectric constant, and dielectric loss tangent, as well as excellent thermal conductivity, bending resistance, and adhesion. In particular, thin molded articles such as sheets and films exhibit excellent bending resistance, bending resistance, and other bending properties, leading to the present invention. The object of the present invention is to provide such a composition and a method for producing the same, a method for producing a sheet and a laminate obtained from such a composition, and such a laminate. [Means for solving the problem]

[0005] The present invention has the following aspects. [1] A composition comprising tetrafluoroethylene polymer particles, spherical boron nitride particles having an average particle diameter of 5 μm or more and 40 μm or less, and non-spherical boron nitride particles having an average particle diameter of less than 15 μm, wherein the mass ratio of the non-spherical boron nitride particles to the total mass of the spherical boron nitride particles and the non-spherical boron nitride particles is less than 30%. [2] The composition according to [1], wherein the tetrafluoroethylene polymer is a heat-meltable tetrafluoroethylene polymer. [3] The composition according to [1] or [2], wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer having an oxygen-containing polar group. [4] The composition according to any one of [1] to [3], wherein the average particle diameter of the tetrafluoroethylene polymer particles is smaller than the average particle diameter of the spherical boron nitride particles and the average particle diameter of the non-spherical boron nitride particles. [5] The composition according to any one of [1] to [4], wherein the average particle diameter of the non-spherical boron nitride particles is smaller than the average particle diameter of the spherical boron nitride particles. [6] The composition according to any one of [1] to [5], wherein the ratio of the average particle diameter of spherical boron nitride to the average particle diameter of non-spherical boron nitride particles is 2.5 or more. [7] The composition according to any one of [1] to [6], wherein the mass ratio of the tetrafluoroethylene polymer particles to the total mass of the tetrafluoroethylene polymer particles, the spherical boron nitride particles, and the non-spherical boron nitride particles is 20% or more and 80% or less. [8] The composition according to any one of [1] to [7], wherein the total content of the tetrafluoroethylene polymer particles, the spherical boron nitride particles, and the non-spherical boron nitride particles in the composition is 50% or more. [9] The composition according to any one of [1] to [8], further comprising a liquid dispersion medium.

[10] A method for producing the composition according to [9], comprising shearing tetrafluoroethylene polymer particles, spherical boron nitride particles having an average particle diameter of 5 μm or more and 40 μm or less, non-spherical boron nitride particles having an average particle diameter of less than 15 μm, and a liquid dispersion medium.

[11] A method for producing the composition according to

[10] , wherein the above shearing treatment is performed by mixing in a tank equipped with a stirring mechanism by thin film rotation or a stirring mechanism by rotation and revolution. A method for producing a sheet, comprising extruding a composition described in any of

[12] [1] to [9] to obtain a sheet containing the tetrafluoroethylene polymer, the spherical boron nitride particles, and the non-spherical boron nitride particles. A method for producing a laminate, comprising applying the composition described in any of

[13] [1] to [9] to the surface of a substrate, heating it to form a polymer layer containing the tetrafluoroethylene polymer, the spherical boron nitride particles, and the non-spherical boron nitride particles, thereby obtaining a laminate having a substrate layer composed of the substrate and the polymer layer.

[14] A laminate having a base layer and a polymer layer comprising the tetrafluoroethylene polymer formed from any of the compositions described in [1] to [9], the spherical boron nitride particles, and the non-spherical boron nitride particles.

[15] The laminate according to

[14] , wherein the thickness of the polymer layer is 20 μm or more and 100 μm or less. [Effects of the Invention]

[0006] According to the present invention, a composition is provided that contains tetrafluoroethylene polymer particles and spherical and non-spherical boron nitride particles having a predetermined average particle size within a predetermined range, and exhibits excellent dispersibility. From such a composition, molded articles and laminates can be formed that have low coefficient of linear expansion, dielectric constant, and dielectric loss tangent, and excellent thermal conductivity, bending resistance, and adhesion. Molded articles obtained from this composition exhibit excellent bending resistance, bending resistance, and other properties, even when they are thin molded articles such as sheets and films. [Modes for carrying out the invention]

[0007] The following terms have the following meanings: The "average particle diameter (D50)" is the 50% cumulative diameter of a particle based on its volume, determined by laser diffraction and scattering. Specifically, the particle size distribution is measured using laser diffraction and scattering, and a cumulative curve is determined with the total volume of the particle collection set to 100%. The D50 is the particle diameter at the point on that cumulative curve where the cumulative volume reaches 50%. The D50 of a particle is determined by dispersing the particle in water and analyzing it using the laser diffraction / scattering method with a laser diffraction / scattering particle size distribution analyzer (LA-920 analyzer, manufactured by Horiba, Ltd.). The "melting temperature" is the temperature corresponding to the maximum value of the melting peak of the polymer measured by differential scanning calorimetry (DSC). The "glass transition temperature (Tg)" is a value measured by analyzing a polymer using the dynamic viscoelasticity measurement (DMA) method. Viscosity is determined by measuring the composition using a B-type viscometer under conditions of 25°C and a rotation speed of 30 rpm. The measurement is repeated three times, and the average of the three measurements is used. The "thixotropic 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 of the three measurements is used. In polymers, a "unit" refers to an atomic group based on a monomer, formed by the polymerization of the monomer. A unit may be directly formed by the polymerization reaction, or it may be a unit in which a portion of the unit is converted to a different structure by processing the polymer. Hereinafter, a unit based on monomer a will also be simply referred to as a "monomer a unit."

[0008] The composition of the present invention (hereinafter also referred to as "this composition") comprises particles of a tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") (hereinafter also referred to as "F particles"), spherical boron nitride particles (hereinafter also referred to as "spherical BN particles") having an average particle diameter of 5 μm or more and 40 μm or less, and non-spherical boron nitride particles (hereinafter also referred to as "non-spherical BN particles") having an average particle diameter of less than 15 μm, wherein the mass ratio of the non-spherical boron nitride particles to the total mass of the spherical boron nitride particles and the non-spherical boron nitride particles is less than 30%.

[0009] This composition exhibits excellent dispersibility, and from it, molded articles can be formed that possess highly desirable physical properties of F polymer and boron nitride particles, with low coefficient of thermal expansion, dielectric constant, and dielectric loss tangent, and excellent thermal conductivity, bending resistance, and adhesion. In particular, even thin molded articles such as sheets and films can be easily formed with excellent bending resistance and bending resistance. The reason for this is not entirely clear, but it is thought to be as follows.

[0010] When spherical boron nitride particles with a small average particle size are blended alone into a resin to improve physical properties such as thermal conductivity, the melt viscosity of the composition tends to increase, reducing moldability, or conversely, the thermal conductivity decreases, making it difficult for the desired properties to be fully expressed in the molded product. Furthermore, when non-spherical boron nitride particles, such as flat or flaky particles, are blended alone, they tend to be oriented in the flow direction during melt molding, resulting in a tendency for the thermal conductivity in the surface direction of the resulting molded product, such as a sheet, to be worse than in the longitudinal direction. When spherical and non-spherical boron nitride particles are blended together in a resin, improvements in these tendencies can be expected, but the form of the composition and molding conditions tend to become more restrictive.

[0011] This composition contains two types of boron nitride particles, spherical BN particles and non-spherical BN particles, each having an average particle diameter within a specific range. As a result, within the molded article made from this composition, non-spherical BN particles are likely to be sandwiched between two or more spherical BN particles. In other words, while the surface of the spherical BN particles is covered with non-spherical BN particles, the formation of a network between the particles is promoted, which is considered to improve the in-plane thermal conductivity when the composition is formed into a sheet or film.

[0012] In particular, this composition contains non-spherical BN particles at a ratio less than a predetermined value with respect to the total amount of spherical BN particles and non-spherical BN particles. Such a small amount of non-spherical BN particles is considered to have excellent dispersibility and be difficult to aggregate, promoting the uniform dispersion of F particles and spherical BN particles. Furthermore, when the composition is processed and molded, a dense and stable packing of the spherical BN particles, which are excessively contained as boron nitride particles, is likely to be formed, which promotes the highly oriented arrangement of non-spherical BN particles in the molded article. In other words, it promotes the formation of heat conduction paths by non-spherical BN particles in the molded article and is also considered to contribute to an improvement in the flexural resistance of the molded article. As a result, it is considered that a thin molded article, such as a sheet or film, which highly possesses the physical properties of the F polymer and boron nitride particles, specifically having a low linear expansion coefficient, dielectric constant, and dielectric tangent, and excellent thermal conductivity, flexural resistance, and adhesiveness, can be obtained from this composition. In this specification, hereinafter, "sheet" is used as a term that collectively refers to both sheets and films.

[0013] The F polymer in the present invention is a polymer containing units based on tetrafluoroethylene (hereinafter, also referred to as "TFE") (hereinafter, also referred to as "TFE units"). The F polymer may be thermally meltable or non-thermally meltable. Here, a thermally meltable polymer means a polymer in which there exists a temperature at which the melt flow rate is 1 to 1000 g / 10 minutes under the condition of a load of 49 N. A non-thermally meltable polymer means a polymer in which there does not exist a temperature at which the melt flow rate is 1 to 1000 g / 10 minutes under the condition of a load of 49 N. The melting temperature of the F polymer that is thermally fusible 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 to 320°C. Within this range, the composition is likely to have excellent processability, and the molded article formed from the composition is likely to have excellent heat resistance.

[0014] 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. The F polymer with such a high fluorine content has low affinity with inorganic particles including boron nitride particles, but according to the present invention, a composition (this composition) excellent in dispersibility can be obtained by the above-described action mechanism. 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 the wetting tension test mixture (manufactured by Wako Pure Chemical Industries, Ltd.) defined in JIS K 6768 on a flat plate made of the F polymer.

[0015] Examples of the F polymer include polytetrafluoroethylene (PTFE), a polymer containing TFE units and units based on ethylene, a polymer containing TFE units and units based on propylene, a polymer (PFA) containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units), and a polymer (FEP) containing TFE units and units based on hexafluoropropylene. PFA and FEP are more preferable, and PFA is even more preferable. These polymers may further contain units based on other comonomers. Examples of PAVE include CF2=CFOCF3, CF2=CFOCF2CF3, and CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE"). PPVE is more preferable.

[0016] The F polymer preferably has an oxygen-containing polar group. The oxygen-containing polar group is preferably a hydroxyl group-containing group or a carbonyl group-containing group, and more preferably a carbonyl group-containing group. In this case, the F particles readily interact with spherical and non-spherical BN particles, resulting in a composition with excellent dispersibility. Furthermore, this composition makes it easy to obtain molded products with low coefficient of thermal expansion, dielectric constant, and dielectric loss tangent, as well as excellent thermal conductivity and adhesion. The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, and -CF2CH2OH and -C(CF3)2OH are more preferred. Preferred carbonyl group-containing groups include carboxyl groups, alkoxycarbonyl groups, amide groups, isocyanate groups, carbamate groups (-OC(O)NH2), acid anhydride residues (-C(O)OC(O)-), imide residues (-C(O)NHC(O)-, etc.), formyl groups, halogenoformyl groups, urethane groups (-NHC(O)O-), carbamoyl groups (-C(O)-NH2), ureido groups (-NH-C(O)-NH2), oxamoyl groups (-NH-C(O)-C(O)-NH2), and carbonate groups (-OC(O)O-), with acid anhydride residues being more preferred. If the F polymer has oxygen-containing polar groups, the number of oxygen-containing polar groups in the F polymer is 1 × 10⁶ carbon atoms in the main chain. 6 The number of oxygen-containing polar groups per polymer is preferably 10 to 5000, and more preferably 100 to 3000. The number of oxygen-containing polar groups in polymer F can be quantified by the polymer composition or by the method described in International Publication No. 2020 / 145133.

[0017] The oxygen-containing polar group may be included in the monomer-based units in the F polymer, or it may be included in the terminal groups of the main chain of the F polymer, with 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 plasma treatment or ionization treatment of the F polymer. The monomers having a carbonyl group are preferably itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), with NAH being more preferred.

[0018] The F polymer is preferably a polymer having carbonyl group-containing groups, including TFE units and PAVE units. More preferably, it is a polymer containing TFE units, PAVE units, and units based on monomers having carbonyl group-containing groups, with these units present in the following proportions relative to the total number of units: 90-99 mol%, 0.99-9.97 mol%, and 0.01-3 mol%. A specific example of such an F polymer is the polymer described in International Publication No. 2018 / 16644.

[0019] In this invention, the F particles are particles of the F polymer, and are preferably non-hollow 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, and more preferably less than 8 μm. In this case, the composition has excellent dispersibility and processability. Furthermore, it is easy to obtain molded articles from this composition that have low coefficient of thermal expansion, dielectric constant and dielectric loss tangent, and excellent thermal conductivity and adhesion (adhesion to the substrate). The specific surface area of ​​F particles is 1 to 25 m². 2 / g is preferable. From the viewpoint of dispersion stability of this composition, the bulk density of F particles is preferably 0.05 g / mL or higher, more preferably 0.08 g / mL or higher. The bulk density of F particles is preferably 0.5 g / mL or lower, more preferably 0.4 g / mL or lower.

[0020] The F particles may be of one type or two or more types. Preferably, the F particles are particles of a heat-meltable F polymer, more preferably particles of a heat-meltable F polymer having a melting temperature of 180 to 320°C and containing oxygen-containing polar groups. In this case, the interaction between the F particles, spherical BN particles, and non-spherical BN particles in the above-described mechanism is enhanced, aggregation of each particle is more easily suppressed, and the dispersibility of the composition is easily improved.

[0021] When using two or more types of F particles, it is preferable that the F particles be a mixture of heat-meltable F polymer particles and non-heat-meltable F polymer particles. In this case, the aggregation-inhibiting effect of the heat-meltable F polymer particles and the retention effect due to fibrillation of the non-heat-meltable F polymer are balanced, and the dispersibility of the composition is easily improved. Furthermore, in the molded product obtained therefrom, the electrical properties of the non-heat-meltable F polymer are highly expressed, and in particular, molded products with low dielectric loss tangent are easily obtained. As for the particles of the heat-meltable F polymer, particles of the heat-meltable F polymer having a melting temperature of 180 to 320°C are preferred, and particles of the heat-meltable F polymer having a melting temperature of 180 to 320°C and having oxygen-containing polar groups are more preferred. The preferred embodiment of the heat-meltable F polymer having oxygen-containing polar groups in the particles of the heat-meltable F polymer is the same as the preferred embodiment of the F polymer having oxygen-containing polar groups described above. As the particles of the non-thermally soluble F polymer, particles of non-thermally soluble PTFE are preferred. Furthermore, the proportion of heat-meltable F polymer particles in the total mass of two or more F particles is preferably 50% by mass or less, and more preferably 40% by mass or less. Moreover, the above proportion is preferably 5% by mass or more, and more preferably 10% by mass or more. Furthermore, it is preferable that the D50 of the heat-meltable F polymer particles is 1 to 4 μm, and the D50 of the non-heat-meltable F polymer particles is 0.1 to 1 μm.

[0022] The F particles may contain resins or inorganic compounds other than the F polymer, and may form a core-shell structure with the F polymer as the core and a resin or inorganic compound other than the F polymer as the shell, or may form a core-shell structure with the F polymer as the shell and a resin or inorganic compound other than the F polymer as the core. Examples of resins other than F polymer include aromatic polyesters, polyamide-imides, polyimides, and maleimides, while examples of inorganic compounds include silica and boron nitride.

[0023] The spherical BN particles contained in this composition are approximately spherical. Here, "approximately spherical" means that when the particles are observed by a scanning electron microscope (SEM), 95% or more of the particles have a ratio of major axis to minor axis (aspect ratio) of 0.7 or higher. The aspect ratio of the spherical BN particles is preferably 1 to 5, and more preferably 1 to 2. The spherical BN particles may be of one type or two or more types, but when two or more types of spherical BN particles are used, the composition tends to have excellent dispersibility and processability. Furthermore, molded products with excellent thermal conductivity and electrical properties can be easily obtained from this composition. Spherical BN particles can be manufactured, for example, by the methods described in Japanese Patent Publication No. 2012-056818 and Japanese Patent No. 5305656. The average particle size (D50) of the spherical BN particles is 5 μm or more and 40 μm or less, preferably 10 μm or more, and more preferably 15 μm or more. The spherical BN particles may be spherical aggregates of primary boron nitride particles. In this case, it is preferable that they be aggregates of flat, plate-like, or other flat-plate-like primary boron nitride particles.

[0024] The non-spherical BN particles contained in this composition refer to all boron nitride particles not included in the spherical BN particles described above, and their shape may be needle-shaped (fibrous), flaky, plate-shaped, etc., with flaky being more preferable. In this case, the composition exhibits excellent dispersibility and processability. Furthermore, molded products with excellent electrical properties can be easily obtained from this composition. The average particle size (D50) of the non-spherical BN particles is less than 15 μm, preferably 12 μm or less, and more preferably 10 μm or less. The D50 of the non-spherical BN particles is preferably 1 μm or more, and more preferably 3 μm or more. The aspect ratio of the non-spherical BN particles is preferably greater than 5, and more preferably 10 or greater. The aspect ratio of the non-spherical BN particles is preferably 10000 or less. Non-spherical BN particles are preferably plate-shaped or flake-shaped. Such non-spherical BN particles are manufactured industrially, and examples include the "UHP" series (manufactured by Showa Denko Corporation) and the "GP" and "HGP" grades of the "Denka Boron Nitride" series (manufactured by Denka Corporation).

[0025] This composition contains F particles, spherical BN particles, and non-spherical BN particles, wherein the mass ratio of non-spherical BN particles to the total mass of spherical BN particles and non-spherical BN particles is less than 30%. Preferably, the mass ratio of non-spherical BN particles to the total mass of spherical BN particles and non-spherical BN particles is 25% or less, and more preferably 20% or less. Preferably, this ratio is 1% or more, and more preferably 5% or more. In this composition, it is preferable that the D50 of the F particles is smaller than that of the spherical BN particles and the non-spherical BN particles. Furthermore, in this composition, it is preferable that the D50 of the non-spherical BN particles is smaller than the D50 of the spherical BN particles. The ratio of the D50 of spherical BN particles to the D50 of non-spherical BN particles is preferably 2.5 or higher, and more preferably 4 or higher. Furthermore, the above ratio is preferably 8 or lower.

[0026] In this composition, it is preferable that the mass ratio of F particles to the total mass of F particles, spherical BN particles, and non-spherical BN particles is 20% or more and 80% or less. More preferably, the mass ratio of F particles to the total mass of F particles, spherical BN particles, and non-spherical BN particles is 35% or more, and even more preferably 40% or more. Such a ratio is more preferably 70% or less, and even more preferably 60% or less. Preferably, the total content of F particles, spherical BN particles, and non-spherical BN particles in this composition is 50% by mass or more. When the content, content ratio, and D50 relationship of F particles, spherical BN particles, and non-spherical BN particles are within the specified range, the composition exhibits excellent dispersibility due to the aforementioned mechanism of action. Furthermore, this composition is preferable from the viewpoint of easily obtaining thin sheets with low coefficient of thermal expansion, dielectric constant, and dielectric loss tangent, as well as excellent thermal conductivity, bending resistance, and adhesion.

[0027] In this composition, it is preferable that the surfaces of the spherical BN particles and non-spherical BN particles are surface-treated with a silane coupling agent. The silane coupling agent may be partially reacted and may form a polysiloxane skeleton. Specific examples of silane coupling agents include, for example, "KBM-573", "KBM-403", "KBM-903", "KBE-903", "KBM-1403", "X-12-967C", "X-12-1214A", "X-12-984S", "X-12-1271A", "KBP-90", "KBM-6803", "X-12-1287A", "KBM-402", "KBE-402", "KBE-403", "KR-516", "KBM-303", "KBM-4803", "KBM-3063", and "KBM-13" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0028] One method for surface-treating spherical and non-spherical BN particles with a silane coupling agent is to mix a solution containing the silane coupling agent with the spherical or non-spherical BN particles and then dry the mixture. In the mixing process, the mixture of the solution and the spherical or non-spherical BN particles may be heated or hydrated to promote the reaction of the silane coupling agent. Alternatively, a reaction catalyst may be used to accelerate the reaction of the silane coupling agent. Furthermore, after drying, the spherical or non-spherical BN particles surface-treated with the silane coupling agent may be crushed or classified. Alternatively, the spherical BN particles and non-spherical BN particles used in this composition may be mixed in advance, and the surface treatment with the silane coupling agent described above may be performed in a single step.

[0029] The composition may further contain other inorganic particles different from the spherical BN particles and non-spherical BN particles described above, as long as the effects of the present invention are not impaired. The shape of the other inorganic particles may be spherical, needle-shaped, fibrous, or plate-shaped. Examples of inorganic compounds in the other inorganic particles include carbon fiber, glass, aluminum nitride, beryllia, silica, wollastonite, talc, cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, or titanium oxide. If the composition further contains other inorganic particles, their content is preferably 1 to 20% by mass relative to the total composition.

[0030] This composition may further contain other resins different from the F polymer. Such other resins may be included in the composition as particles, or, if the composition contains a liquid dispersion medium as described later, they may be included dissolved or dispersed in the liquid dispersion medium. Other resins include polyester resins such as liquid crystalline aromatic polyesters, polyimide resins, polyamide-imide resins, epoxy resins, maleimide resins, urethane resins, polyphenylene ether resins, polyphenylene oxide resins, and polyphenylene sulfide resins. Other resins include aromatic polymers, and more preferably at least one aromatic imide polymer selected from the group consisting of aromatic polyimides, aromatic polyamic acids, aromatic polyamideimides, and precursors of aromatic polyamideimides. The aromatic polymer is preferably included in the composition as a varnish dissolved in a liquid dispersion medium. If the composition further contains other resins, their content is preferably 0.1 to 5% by mass relative to the total composition.

[0031] This composition may be in powder form, liquid form (dispersed liquid, slurry form) containing a liquid dispersion medium, or in paste form. Furthermore, the powdered composition may be further melted to form pelletized compositions. The composition is preferably in a liquid state (dispersed liquid, slurry) that further contains a liquid dispersion medium. When the composition is in a liquid state, the dispersibility of F particles, spherical BN particles, and non-spherical BN particles is excellent, and the above-mentioned mechanism of action based on spherical BN particles and non-spherical BN particles is more easily expressed, making it easier to obtain a sheet with excellent thermal conductivity and bending resistance. The liquid dispersion medium is preferably a compound that is liquid at atmospheric pressure and 25°C, 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 mediums are used, it is preferable that the two liquid dispersion mediums are mutually compatible.

[0032] The liquid dispersion medium is preferably a compound selected from the group consisting of water, amides, ketones, and esters. Examples of amides 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 ketones 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 esters 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.

[0033] If the composition contains a liquid dispersion medium, the content of the liquid dispersion medium is preferably in the range of 10 to 70% by mass relative to the total composition. If the composition contains a liquid dispersion medium, the solid content concentration in the composition is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. The solid content concentration is preferably 90% by mass or less, and more preferably 60% by mass or less. The term "solid content" refers to the total amount of substances that form solid content in molded articles such as sheets formed from this composition. Specifically, F particles, spherical BN particles, and non-spherical BN particles are solid content, and if this composition contains other resins or other inorganic particles, these other resins or other inorganic particles are also solid content, and the total mass ratio of these components represents the solid content concentration in this composition.

[0034] If the composition contains a liquid dispersion medium, it is preferable that the composition further contains a surfactant from the viewpoint of improving dispersion stability. Such a surfactant is preferably a nonionic surfactant. Specific examples of nonionic surfactants include the "Futergent" series (manufactured by Neos Co., Ltd.), 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", "BYK-3456" (manufactured by Bic Chemie Japan Co., Ltd.), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), and the "Tergitol" series (manufactured by Dow Chemical Corporation, such as "Tergitol TMN-100X"). If the composition contains a nonionic surfactant, the content of the nonionic surfactant in the composition is preferably 0.1 to 10% by mass relative to the total composition.

[0035] This composition may further contain a silane coupling agent as needed. Examples of silane coupling agents include those similar to those used for surface treatment of spherical and non-spherical BN particles. When this composition contains a silane coupling agent, the content of the silane coupling agent in this composition is preferably 0.1 to 10% by mass relative to the total composition.

[0036] This composition may further contain additives such as thixotropic agents, viscosity modifiers, defoamers, dehydrators, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, surface treatment agents other than the silane coupling agents mentioned above, and flame retardants.

[0037] When the composition contains a liquid dispersion medium and is in a liquid state, its viscosity is preferably 10 mPa·s or more, and more preferably 100 mPa·s or more. The viscosity of the composition is preferably 10,000 mPa·s or less, and more preferably 3,000 mPa·s or less. When this composition contains a liquid dispersion medium and is in liquid form, its thixotropy ratio is preferably 1.0 to 3.0. When this composition contains water as a liquid dispersion medium, its pH is more preferably 8 to 10 from the viewpoint of improving long-term storage. The pH of such a composition can be adjusted by a pH adjusting agent (amine, ammonia, citric acid, etc.) or a pH buffering agent (tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium bicarbonate, ammonium carbonate, ammonium acetate, etc.).

[0038] This composition is obtained by mixing F particles, spherical BN particles, and non-spherical BN particles with other resins, other inorganic particles, liquid dispersion media, surfactants, silane coupling agents, additives, etc., as needed. This composition may be obtained by mixing F particles, spherical BN particles, and non-spherical BN particles all at once, or by mixing them separately sequentially, or by preparing a masterbatch of these particles in advance and mixing it with the remaining components. There are no particular restrictions on the order of mixing, and the mixing method may be a single mixing or mixing in multiple stages. Examples of mixing apparatus for obtaining this composition include stirring devices equipped with blades such as Henschel mixers, pressure kneaders, Banbury mixers, and planetary mixers; grinding devices equipped with media such as ball mills, attritors, basket mills, sand mills, sand grinders, Dino mills, disper mats, SC mills, spike mills, and agitator mills; and dispersion devices equipped with other mechanisms such as microfluidizers, nanomizers, ultimateizers, ultrasonic homogenizers, desolvers, dispersers, high-speed impellers, thin-film swirling high-speed mixers, rotating and revolving agitators, and V-type mixers. A planetary mixer is a stirring device that has two stirring blades that rotate on their own axis and revolve around each other. A thin-film swirling high-speed mixer is a stirring device that spreads F particles and a liquid dispersion medium in a thin film on the inner wall surface of a cylindrical stirring tank and swirls it around, mixing while applying centrifugal force.

[0039] An example of a method for producing the composition containing a liquid dispersion medium is a method in which F particles, spherical BN particles, non-spherical BN particles, and the liquid dispersion medium are preferably added together and subjected to a shearing treatment to obtain the composition. In this case, the shearing treatment is preferably carried out by mixing in a tank equipped with a stirring mechanism using a thin film swirling mechanism or a stirring mechanism using rotation and revolution, and it is preferable to carry out the shearing treatment using a thin film swirling high-speed mixer, a planetary mixer, or a rotation and revolution agitator. Another example of a method for producing the composition containing a liquid dispersion medium is a method in which F particles, spherical BN particles, non-spherical BN particles, and a portion of the liquid dispersion medium are kneaded together to obtain a mixture, and then this mixture is added to the remaining liquid dispersion medium to obtain the composition. The liquid dispersion medium used during kneading and addition may be of the same type or of a different type. The spherical BN particles, non-spherical BN particles, other resins, other inorganic particles, surfactants, silane coupling agents, and additives may be mixed during kneading or during addition. Mixing during kneading is preferably carried out using a planetary mixer or a rotating agitator.

[0040] The mixture obtained by kneading may be in the form of a paste (such as a paste with a viscosity of 1,000 to 100,000 mPa·s) or a wet powder (such as a wet powder with a viscosity of 10,000 to 100,000 Pa·s as measured by a capillograph). The viscosity measured by the capillary graph is calculated using a capillary with a length of 10 mm and a 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 This is the value measured as such.

[0041] When this composition is subjected to a molding method such as extrusion, molded products such as sheets can be obtained. If the composition is a liquid containing a liquid dispersion medium, it is preferable to extrude the composition into a sheet. The sheet obtained by extrusion may be further cast by press molding, calendering, etc. It is preferable to further heat the sheet to remove the liquid dispersion medium and calcine the F polymer. If the composition is in powder form, it is preferable to melt-extrude the composition. Extrusion molding can be carried out using a single-screw extruder, a multi-screw extruder, or the like. Alternatively, a molded product may be obtained by injection molding this composition. When forming a molded product, the composition may be directly melt-extruded or injection-molded, or the composition may be melt-kneaded to form pellets, and then the pellets may be melt-extruded or injection-molded to obtain a molded product such as a sheet.

[0042] The thickness of the sheet obtained from this composition is preferably 20 μm to 100 μm. Due to the mechanism of action of this composition described above, such a sheet exhibits excellent bendability, such as resistance to bending and folding, even when thin. The linear expansion coefficient of the sheet is preferably 100 ppm / °C or less, and more preferably 80 ppm / °C or less. The lower limit of the linear expansion coefficient of the sheet is 1 ppm / °C. Note that the linear expansion coefficient refers to the value measured for the linear expansion coefficient of the test specimen in the range of 25°C to 260°C, 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 higher, and more preferably 3.0 W / m·K or higher. The upper limit of the sheet's thermal conductivity is 100 W / m·K.

[0043] A laminate can be formed by laminating such sheets onto a substrate. Methods for manufacturing the laminate include using a co-extruder as the extruder and extruding the composition together with the raw materials of the substrate, extruding the composition onto the substrate, and heat-pressing the sheet and the substrate together. Examples of substrates include metal substrates (metal foils made of copper, nickel, aluminum, titanium, and their alloys), heat-resistant resin films (heat-resistant resin films such as polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamide-imide, liquid crystalline polyester, and tetrafluoroethylene polymers), prepreg substrates (precursors for fiber-reinforced resin substrates), ceramic substrates (ceramic substrates such as silicon carbide, aluminum nitride, and silicon nitride), and glass substrates.

[0044] The substrate can take the shape of a flat, curved, or uneven surface. Furthermore, the substrate may be in the form of foil, plate, film, or fiber. The surface roughness of the substrate with a ten-point average is preferably 0.01 to 0.05 μm. The surface of the substrate may be surface-treated with a silane coupling agent or plasma-treated. Preferred silane coupling agents include those having functional groups such as 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-isocyanatetopropyltriethoxysilane. The peel strength between the sheet and the substrate is preferably 2 kN / m or more, and more preferably 2.5 kN / m or more. The above peel strength is preferably 10 kN / m or less.

[0045] Furthermore, by applying this composition to the surface of a substrate and heating it to form a polymer layer containing F polymer, spherical BN particles, and non-spherical BN 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 the liquid dispersion medium on the surface of the substrate, heating to remove the dispersion medium, and then heating again to bake the F polymer. Examples of suitable substrates include those similar to those that can be laminated with the aforementioned sheet, and the preferred embodiments are also similar.

[0046] Methods for distributing the composition include coating, droplet dispensing, and immersion, with roll coating, knife coating, bar coating, die coating, or spraying being preferred. When removing the liquid dispersion medium, heating is preferably carried out at 100-200°C for 0.1-30 minutes. During this heating, it is not necessary to completely remove the liquid dispersion medium; it is sufficient to remove it to the extent that the layer formed by the packing of F particles, spherical BN particles, and non-spherical BN particles can maintain a self-supporting film. In addition, during heating, air may be blown on to promote the removal of the liquid dispersion medium by air drying. When heating the F polymer for firing, it is preferable to do so at a temperature higher than the firing temperature of the F polymer, and more preferably at 360-400°C for 0.1-30 minutes. Examples of heating devices for each heating process include ovens and forced-air drying ovens. The heat source in the device may be a contact-type heat source (hot air, hot plate, etc.) or a non-contact heat source (infrared radiation, etc.). Furthermore, each heating process may be carried out under normal pressure or under reduced pressure. Furthermore, the atmosphere used for each heating process may be either an air atmosphere or an inert gas atmosphere (such as helium, neon, argon, or nitrogen).

[0047] The polymer layer is formed by the steps of placing and heating the composition. These steps may be performed once or repeated two or more times. For example, the composition may be placed on the surface of a substrate and heated to form a polymer layer, and then the composition may be placed on the surface of the polymer layer and heated to form a second polymer layer. Alternatively, the composition may be placed on the surface of a substrate, heated to remove the liquid dispersion medium, and then the composition may be placed on that surface and heated to form a polymer layer. The thickness of the polymer layer is preferably 20 μm or more and 100 μm or less. The thickness of the polymer layer is more preferably 50 μm or less, and even more preferably less than 50 μm. Due to the aforementioned mechanism of action of this composition, such polymer layers exhibit excellent flexibility, including bending resistance and kinking resistance, even when thin. This composition may be arranged on only one surface of the substrate, or on both surfaces of the substrate. In the former case, a laminate is obtained having a substrate layer and a polymer layer on one surface of the substrate layer. In the latter case, a laminate is obtained having a substrate layer and polymer layers on both surfaces of the substrate layer.

[0048] Suitable examples of laminates include a metal-clad laminate having a metal foil and a polymer layer on at least one surface of the metal foil, and a polyimide film and a multilayer film having polymer layers on both surfaces of the polyimide film. The preferred ranges for the linear expansion coefficient of the polymer layer, the thermal conductivity in the in-plane direction, and the peel strength between the polymer layer and the substrate layer are the same as those for the linear expansion coefficient, thermal conductivity in the in-plane direction, and peel strength between the sheet and the substrate layer in the sheet obtained from the above-described composition.

[0049] This composition is useful as a material for providing insulation, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, and thermal conductivity. Specifically, this composition can be used in printed circuit 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, condensers (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode binders, electrode separators, and electrodes (positive and negative electrodes). Furthermore, this composition is also useful as an adhesive for bonding components. Specifically, it can be used for bonding ceramic components, metal components, electronic components such as IC chips, resistors, and capacitors on substrates of semiconductor elements and module components, bonding circuit boards to heat sinks, and bonding LED chips to substrates. Furthermore, this composition can be suitably used in applications requiring conductivity, such as in the field of printed electronics. Specifically, it can be used in the manufacture of conductive elements in printed circuit boards, sensor electrodes, and the like.

[0050] Molded articles, sheets, and laminates formed from this composition are useful as antenna components, printed circuit boards, aircraft components, automobile components, sports equipment, food industry products, heat dissipation components, and the like. Specifically, these include wire insulation materials (aircraft wires, etc.), enamel wire insulation materials used in motors for electric vehicles, etc., electrical insulation tapes, insulating tapes for oil drilling, oil transport hoses, hydrogen tanks, printed circuit board materials, 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, car dashboards, covers for home appliances, sliding components (load bearings, yaw bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear rings). It is useful in applications such as gears, 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 for centrifugal pumps, chemical and water supply pumps, tools (shovels, files, drills, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, racket strings, dies, toilets, container coverings, mounting heat dissipation substrates for power devices, heat dissipation components for wireless communication devices, transistors, thyristors, rectifiers, transformers, power MOS FETs, CPUs, heat sinks, metal heat sinks, blades for wind turbines, wind power generation equipment and aircraft, casings 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, heat dissipation components in processing units such as sputtering and various dry etching equipment, and as electromagnetic shielding. Molded articles, sheets, and laminates formed from this composition are particularly useful as electronic substrate materials such as flexible printed circuit boards and rigid printed circuit boards for automotive electronics such as LED headlamps, power control units, or electric control units, as well as as heat dissipation sheets and substrates, and heat dissipation substrates for automobiles. When using molded articles, sheets, and laminates formed from this composition as heat dissipation members, the molded articles, sheets, or laminates may be directly bonded to the target substrate, or they may be bonded to the target substrate via an adhesive layer such as a silicone-based adhesive layer.

[0051] Although the present invention has described the composition, the method for manufacturing the composition, the method for manufacturing a sheet, the method for manufacturing a laminate, and the laminate, the present invention is not limited to the configuration of the embodiments described above. For example, the composition and laminate may have additional configurations in the above embodiment, or may be replaced with any configuration that performs a similar function. Furthermore, the manufacturing methods for the composition, sheet, or laminate may each have additional steps in the above embodiment, or may be replaced with any steps that produce a similar effect. [Examples]

[0052] 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 particle 1: Contains TFE units, NAH units, and PPVE units in the following order: 97.9 mol%, 0.1 mol%, and 2.0 mol%, respectively, with a carbonyl group containing a main chain of 1 × 10¹⁶ carbon atoms. 6 Particles of tetrafluoroethylene polymer (melting temperature: 300°C) with 1000 particles per unit (D50: 2.1 μm) [Boron nitride particles] Boron nitride particle 1: Spherical boron nitride particle (D50: 12 μm) Boron nitride particles 2: Spherical boron nitride particles (D50: 45 μm) Boron nitride particles 3: Non-spherical (flaky) boron nitride particles (D50: 4 μm) Boron nitride particles 4: Non-spherical (flaky) boron nitride particles (D50: 15 μm) [Liquid dispersion medium] NMP:N-methyl-2-pyrrolidone

[0053] 2. Examples of composition manufacturing [Example 1] F particles 1, boron nitride particles 1, boron nitride particles 3, and NMP were kneaded in a planetary mixer to obtain a wet powder mixture 1. Further, NMP was added in several batches and stirred to obtain a liquid composition 1 containing F particles 1 (30 parts by mass), boron nitride particles (30 parts by mass; boron nitride particles 1:boron nitride particles 3 = 80:20 (mass ratio)), and NMP (40 parts by mass). [Example 2] A liquid composition 2 was obtained in the same manner as in Example 1, except that the mass ratio of boron nitride particle 1 to boron nitride particle 3 was changed, and the composition 2 contained F particle 1 (30 parts by mass), boron nitride particle (30 parts by mass; boron nitride particle 1:boron nitride particle 3 = 75:25 (mass ratio)), and NMP (40 parts by mass).

[0054] [Example 3] A liquid composition 3 was obtained in the same manner as in Example 1, except that boron nitride particle 1 was replaced with boron nitride particle 2, and the composition contained F particle 1 (30 parts by mass), boron nitride particle (30 parts by mass; boron nitride particle 2:boron nitride particle 3 = 70:30 (mass ratio)), and NMP (40 parts by mass). [Example 4] A liquid composition 4 was obtained in the same manner as in Example 1, except that boron nitride particle 3 was replaced with boron nitride particle 4, and the composition contained F particle 1 (30 parts by mass), boron nitride particle (30 parts by mass; boron nitride particle 1:boron nitride particle 4 = 70:30 (mass ratio)), and NMP (40 parts by mass). [Example 5] F particles 1, boron nitride particles 1, and NMP were kneaded in a planetary mixer to obtain a wet powder mixture 1. Further NMP was added in several batches and stirred to obtain a liquid composition 5 containing F particles 1 (30 parts by mass), boron nitride particles (30 parts by mass), and NMP (40 parts by mass).

[0055] 3. Manufacturing of the laminate Composition 1 was applied to the surface of a long piece of copper foil using a bar coater to form a wet film. Next, the copper foil with the wet film was dried in a drying oven at 110°C for 5 minutes to form a dry film. After that, the copper foil with the dry film was heated in a nitrogen oven at 380°C for 3 minutes. This produced a laminate 1 having copper foil and a polymer layer with a thickness of 100 μm on its surface containing molten F particles 1, boron nitride particles 1 and boron nitride particles 3. Laminates 2 to 5 were manufactured from compositions 2 to 5 in the same manner as laminate 1.

[0056] 4. Evaluation of the laminate 4-1. Peel strength of the laminate Rectangular test specimens (100 mm long, 10 mm wide) were cut from each laminate. Then, the copper foil and polymer layer were peeled off at a position 50 mm from one end of the specimen in the longitudinal direction, and at a tensile speed of 50 mm / min, at a 90° angle to the specimen from the other end in the longitudinal direction. The maximum load applied during this process was measured as the peel strength (N / cm) and evaluated according to the following criteria. [Evaluation Criteria] ○:2kN / m or more △: 1kN / m or more and less than 2kN ×: Less than 1kN / m

[0057] 4-2.Boldability For each laminate, the copper foil of the laminate was removed by etching with a ferric chloride aqueous solution to prepare a sheet of a single polymer layer. A 5 mm square test specimen was cut from the prepared sheet, bent 180° under conditions of a radius of curvature (300 μm), a load (50 mN, 1 minute) was applied from above, and then the bend was reversed. The appearance of the test specimen was evaluated according to the following criteria. [Evaluation Criteria] ○: No external abnormalities are observed at the fold. △: Whitening was observed in the folded area. ×: Torn at the fold.

[0058] 4-3. Thermal conductivity A 10mm x 10mm square test specimen was cut from the center of each sheet obtained in the same manner as in 4-2, and its in-plane thermal conductivity (W / m·K) was measured and evaluated according to the following criteria. [Evaluation Criteria] 〇: More than 2W / m·K △: 1W / m·K or more and 2W / m·K or less ×: Less than 1 W / m·K The evaluation results are summarized in Table 1.

[0059] [Table 1] [Industrial applicability]

[0060] As is clear from the above results, this composition exhibits excellent dispersion stability, and the laminate formed from this composition exhibits high levels of physical properties of the F polymer and boron nitride particles, resulting in excellent peel strength (adhesion), thermal conductivity, and further excellent bending resistance.

[0061] Furthermore, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2022-030107, filed on February 28, 2022, are incorporated herein by reference as disclosure of the specification of the present invention.

Claims

1. A composition comprising particles of a heat-meltable tetrafluoroethylene polymer having a melting temperature of 260°C or more and 320°C or less, spherical boron nitride particles having an average particle diameter of 5 μm or more and 40 μm or less, and non-spherical boron nitride particles having an average particle diameter of less than 15 μm, wherein the average particle diameter of the tetrafluoroethylene polymer particles is smaller than the average particle diameter of the spherical boron nitride particles and the average particle diameter of the non-spherical boron nitride particles, and the mass ratio of the non-spherical boron nitride particles to the total mass of the spherical boron nitride particles and the non-spherical boron nitride particles is less than 30%.

2. The composition according to claim 1, wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer having an oxygen-containing polar group.

3. The composition according to claim 1, wherein the average particle diameter of the non-spherical boron nitride particles is smaller than the average particle diameter of the spherical boron nitride particles.

4. The composition according to claim 1, wherein the ratio of the average particle diameter of spherical boron nitride to the average particle diameter of non-spherical boron nitride particles is 2.5 or more.

5. The composition according to claim 1, wherein the mass ratio of the tetrafluoroethylene polymer particles to the total mass of the tetrafluoroethylene polymer particles, the spherical boron nitride particles, and the non-spherical boron nitride particles is 20% or more and 80% or less.

6. The composition according to claim 1, wherein the total content of the tetrafluoroethylene polymer particles, the spherical boron nitride particles, and the non-spherical boron nitride particles in the composition is 50% or more.

7. The composition according to claim 1, further comprising a liquid dispersion medium.

8. A method for producing the composition according to claim 7, comprising shearing tetrafluoroethylene polymer particles, spherical boron nitride particles having an average particle diameter of 5 μm or more and 40 μm or less, non-spherical boron nitride particles having an average particle diameter of less than 15 μm, and a liquid dispersion medium.

9. A method for producing the composition according to claim 8, wherein the shearing treatment is performed by mixing in a tank equipped with a stirring mechanism by rotating a thin film or by rotation and revolution.

10. A method for producing a sheet, comprising extruding the composition according to claim 1 to obtain a sheet containing the tetrafluoroethylene polymer, the spherical boron nitride particles, and the non-spherical boron nitride particles.

11. A method for producing a laminate, comprising applying the composition described in claim 1 to the surface of a substrate and heating it to form a polymer layer containing the tetrafluoroethylene polymer, the spherical boron nitride particles, and the non-spherical boron nitride particles, thereby obtaining a laminate having a substrate layer composed of the substrate and the polymer layer.

12. A laminate comprising a base layer and a polymer layer formed from the composition described in claim 1, the tetrafluoroethylene polymer, the spherical boron nitride particles, and the non-spherical boron nitride particles.

13. The laminate according to claim 12, wherein the thickness of the polymer layer is 20 μm or more and 100 μm or less.

Images