Liquid composition, method for producing liquid composition, laminate, and method for producing laminate

Abstract

The liquid composition contains particles containing a heat-fusible tetrafluoroethylene-based polymer, spherical boron nitride particles having an average particle diameter of 1 [mu] m or less, inorganic particles having an average particle diameter of greater than 1 [mu] m, and a liquid dispersion medium.

Description

Technical Field

[0001] This disclosure relates to liquid compositions, methods for manufacturing liquid compositions, laminates, and methods for manufacturing laminates. Background Technology

[0002] Fluoropolymers possess excellent electrical properties, water and oil repellency, chemical resistance, and heat resistance, making them suitable for various applications. In particular, tetrafluoroethylene polymers, due to their superior mold release properties, electrical insulation, water and oil repellency, chemical resistance, weather resistance, and heat resistance, are processed into various molded products for application.

[0003] For example, Patent Document 1 describes a composition containing fluororesin and boron nitride for manufacturing foamed molded articles.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5757347 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] Patent Document 1 describes the process of manufacturing by melt-blending fluoropolymers and boron nitride. However, tetrafluoroethylene polymers generally have high melt viscosity, requiring significant stress when melt-blending them with boron nitride. This can impair the thermal conductivity and insulation properties of boron nitride, leading to a decline in the properties of boron nitride in the molded product.

[0009] In response, the inventors investigated the use of a liquid composition containing a liquid dispersion medium to replace the solid composition manufactured by melt mixing. They found that, compared to a solid liquid composition, the original properties of boron nitride are less likely to be damaged during manufacturing, even without the application of strong stress.

[0010] However, it is known that the behavior of each component in a liquid composition is quite complex, and the particles contained in the liquid composition tend to settle, making it difficult to control the behavior of the particles in the liquid. If the particles contained in the liquid composition settle, the physical properties (e.g., thermal conductivity) of the molded article formed from the liquid composition will also tend to decrease.

[0011] In view of this situation, one embodiment of the present disclosure provides a liquid composition comprising particles of a hot-melt tetrafluoroethylene polymer, boron nitride particles and inorganic particles in which sedimentation is suppressed, a method for manufacturing the liquid composition, and a method for manufacturing a laminate using the liquid composition and a laminate.

[0012] Technical solutions adopted to solve technical problems

[0013] This disclosure includes the following forms.

[0014] <1> A liquid composition comprising: particles containing a thermomeltable tetrafluoroethylene polymer, boron nitride spherical particles with an average particle size of less than 1 μm, inorganic particles with an average particle size of greater than 1 μm, and a liquid dispersion medium.

[0015] <2> The liquid composition as described in <1>, wherein the hot-melt tetrafluoroethylene polymer comprises: a tetrafluoroethylene-based unit, and at least one of a perfluoro(alkyl vinyl ether)-based unit and a hexafluoropropylene-based unit.

[0016] <3> The liquid composition as described in <1> or <2>, wherein the hot-melt tetrafluoroethylene polymer has a carbonyl group.

[0017] <4> The liquid composition as described in any one of <1> to <3>, wherein the hot-melt tetrafluoroethylene polymer has a per 1×10 6 Each main chain has 10 to 5000 carbon atoms and contains carbonyl groups.

[0018] <5> The liquid composition as described in any one of <1> to <4>, wherein the specific surface area of ​​the particles of the hot-melt tetrafluoroethylene polymer is greater than 6 m². 4 / g.

[0019] <6> The liquid composition as described in any one of <1> to <5>, wherein the specific surface area of ​​the boron nitride spherical particles is 10 m². 5 / g or more.

[0020] <7> The liquid composition as described in any one of <1> to <6>, wherein the ratio of the specific surface area of ​​the boron nitride spherical particles to the specific surface area of ​​the particles of the hot-melt tetrafluoroethylene polymer is less than 2.0.

[0021] <8> The liquid composition as described in any one of <1> to <7>, wherein the inorganic particles comprise at least one particle selected from oxides, nitrides, metal monomers, alloys and carbon.

[0022] <9> The liquid composition as described in any one of <1> to <8>, wherein the total amount of the boron nitride spherical particles and the inorganic particles is in a ratio of 50 to 200 by volume to the amount of the particles comprising the thermomeltable tetrafluoroethylene polymer.

[0023] <10> The liquid composition as described in any one of <1> to <9>, wherein, based on volume, the ratio of the content of the boron nitride spherical particles to the content of the inorganic particles is 0.01 to 1.

[0024] <11> The liquid composition as described in any one of <1> to <10>, wherein the liquid dispersion medium comprises at least one selected from water, ketones, amides and esters.

[0025] A method for manufacturing the liquid composition according to any one of <12>, <1> to <11>, wherein after mixing the particles comprising a hot-melt tetrafluoroethylene polymer, a liquid dispersion medium and the boron nitride particles with an average particle size of less than 1 μm, the inorganic particles with an average particle size of greater than 1 μm are mixed.

[0026] <13> A laminated body having: Substrate, and The fluororesin layer disposed on the substrate contains a hot-melt tetrafluoroethylene polymer, boron nitride spherical particles with an average particle size of less than 1 μm, and inorganic particles with an average particle size of greater than 1 μm.

[0027] <14> A method for manufacturing a laminate, wherein a liquid composition as described in any one of <1> to <11> is applied to a substrate, the liquid dispersion medium is removed by heating, and the particles comprising a thermomeltable tetrafluoroethylene polymer are further heated to melt and sinter.

[0028] Invention Effects

[0029] According to one embodiment of the present disclosure, a liquid composition comprising particles of a hot-melt tetrafluoroethylene polymer, boron nitride particles and inorganic particles, wherein sedimentation is suppressed, a method for manufacturing the liquid composition, and a method for manufacturing a laminate using the liquid composition and a laminate are provided. Detailed Implementation

[0030] The embodiments of this disclosure will now be described in detail. However, this disclosure is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless otherwise specified. Similarly, numerical values ​​and their ranges are not intended to limit the embodiments of this disclosure.

[0031] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes whose purpose can be achieved when they cannot be clearly distinguished from other processes.

[0032] In this disclosure, the range of values ​​represented by “~” includes the values ​​recorded before and after “~” as the minimum and maximum values, respectively.

[0033] In this disclosure, each component may contain multiple corresponding substances. In the presence of multiple substances corresponding to each component in the liquid composition, unless otherwise specified, the content or percentage of each component refers to the total content or total amount of the multiple substances present in the liquid composition.

[0034] In this disclosure, the particles corresponding to each component may comprise multiple types. In the case where multiple particles corresponding to each component are present in the liquid composition, unless otherwise specified, the particle size of each component refers to the value of a mixture of the multiple particles present in the liquid composition.

[0035] In this disclosure, the terms "layer" or "film" include, in addition to the case where the layer or film is formed throughout the region in which it is observed, the case where it is formed only in a part of the region.

[0036] In this disclosure, the term "stacked" refers to stacking layers together, which can be two or more layers combined together, or two or more layers that can be detached.

[0037] In this disclosure, a "unit" in a polymer refers to a group of atoms based on a monomer formed by the polymerization of the monomer. A unit can be formed directly through a polymerization reaction, or it can be obtained by processing the polymer to convert a portion of the unit into another structure. Hereinafter, a unit based on monomer a will also be referred to as a "monomer a unit".

[0038] In this disclosure, the “melting temperature” of a thermomeltable tetrafluoroethylene polymer refers to the temperature corresponding to the maximum value of the polymer’s melting peak as determined by differential scanning calorimetry (DSC).

[0039] In this disclosure, the “melt flow rate” of hot-melt tetrafluoroethylene polymers refers to the melt flow rate of polymers specified in JIS K 7210-1:2014 (ISO 1133-1:2011).

[0040] In this disclosure, the "glass transition temperature (Tg)" of the hot-melt tetrafluoroethylene polymer is a value determined by analyzing the polymer using the dynamic viscoelasticity assay (DMA).

[0041] In this disclosure, the average particle size refers to the volume average particle size (D50), which is the cumulative 50% diameter of the particle's volume as determined by laser diffraction and scattering. That is, the particle size distribution is determined by laser diffraction and scattering, and a cumulative curve is obtained with the total volume of the particle group as 100%. The particle D50 is obtained by dispersing the particles in water and analyzing them using a laser diffraction and scattering particle size distribution measuring device (e.g., the BECKMAN COULTER laser diffraction and scattering particle size distribution measuring device "LS-13 320").

[0042] In this disclosure, the "average roundness" of a particle is a value calculated from the roundness of 100 randomly selected particles using the following formula. In the formula, Ci represents roundness, and fi represents the frequency of the particle. Roundness is the ratio of the equivalent circumference of the projected area of ​​a particle to the circumference of the particle's projected image when measured using a flow-through particle image analysis device (e.g., FPIA-3000 (manufactured by SYSMEX Corporation)).

[0043]

Mathematical Formula 1

[0044] In this disclosure, the "aspect ratio" of a particle refers to the ratio of its major axis to its minor axis (major axis / minor axis) when observed using SEM. The aspect ratio of a particle is the average of the aspect ratios of 100 randomly selected particles.

[0045] In this disclosure, the "specific surface area" is a value obtained by measuring and calculating the particles using the gas adsorption (constant volume method) BET multi-point method, and is obtained using a BET specific surface area measuring device (e.g., NOVA4200e (manufactured by Quantachrom Instruments Co., Ltd.)). Furthermore, the "specific surface area" of the boron nitride particles is a value calculated using nitrogen gas according to JIS Z 8830:2013.

[0046] In this disclosure, the "viscosity" of the liquid composition is determined by measuring the composition using a type B viscometer at 25°C and 30 rpm. The measurement is repeated three times, and the average of the three measurements is taken.

[0047] In this disclosure, the "thixotropic ratio" of the liquid composition refers to the value calculated by dividing the viscosity η1 measured at 30 rpm by the viscosity η2 measured at 60 rpm. Each viscosity measurement is repeated three times, and the average of the three measurements is taken.

[0048] <Liquid Composition>

[0049] The liquid composition disclosed herein comprises: particles containing a hot-melt tetrafluoroethylene polymer, boron nitride spherical particles with an average particle size of less than 1 μm, inorganic particles with an average particle size of greater than 1 μm, and a liquid dispersion medium.

[0050] Hereinafter, thermoplastic tetrafluoroethylene polymers are also referred to as "F polymers", and particles containing thermoplastic tetrafluoroethylene polymers are also referred to as "F particles". In addition, boron nitride is also referred to as "BN", and spherical boron nitride particles are also referred to as "spherical BN particles". Furthermore, inorganic particles with an average particle size greater than 1 μm are also referred to as "large-diameter inorganic particles".

[0051] In the liquid composition described above, the sedimentation of F particles, spherical BN particles, and large-diameter inorganic particles is suppressed. The reason for this is not yet clear, but it is speculated as follows.

[0052] Because the average particle size of the spherical BN particles contained in the liquid composition is less than 1 μm, the spherical BN particles and F particles in the liquid composition tend to easily form approximately unified composite particles. At this time, due to the spherical shape of the BN particles, they act as a lubricant on the surface of the formed composite particles, suppressing the aggregation of the composite particles and easily inhibiting sedimentation caused by giantification. Furthermore, since the spherical BN particles are inorganic particles, their interaction with large-diameter inorganic particles is enhanced compared to F particles, which are organic particles, tending to stabilize the viscosity and other liquid properties of the liquid composition. This tendency is related to the homogeneous dispersion of the components in the liquid composition, promoting the formation of a dense matrix structure in the molded article formed from the liquid composition. Moreover, due to the excellent thermal conductivity of BN, the formation of thermally conductive channels from the dense matrix structure is expected to improve the thermal conductivity of the molded article.

[0053] In particular, when the specific surface area of ​​F particles and the specific surface area of ​​spherical BN particles are in a defined relationship, specifically when the specific surface area of ​​spherical BN particles is within a defined range relative to the specific surface area of ​​F particles, the formation of near-composite particles is further promoted, and this tendency tends to become more pronounced.

[0054] The following describes the components contained in the liquid composition.

[0055] (F particle)

[0056] The F polymer contained in the F particles is a polymer containing tetrafluoroethylene (hereinafter also referred to as "TFE unit")-based units (hereinafter also referred to as "TFE units"). From the viewpoint of advantageously exhibiting the properties brought about by the TFE units, the content of TFE units in the F polymer is preferably 50 mol% or more, more preferably 90 mol% or more, relative to all units in the F polymer. The above-mentioned content can be 99 mol% or less, or 98 mol% or less.

[0057] Polymer F is thermomeltable. Thermomeltable polymers are polymers that exhibit a melt flow rate of 1–1000 g / 10 minutes under a load of 49 N.

[0058] From the viewpoint of heat resistance, the melting temperature of polymer F is preferably above 200°C, more preferably above 260°C. From the viewpoint of ease of processing, the melting temperature of polymer F is preferably below 325°C, more preferably below 320°C.

[0059] From the viewpoint of heat resistance, the glass transition temperature of polymer F is preferably 50°C or higher, more preferably 75°C or higher. From the viewpoint of ease of processing, the glass transition temperature of polymer F is preferably 150°C or lower, more preferably 125°C or lower.

[0060] From the viewpoint of advantageously exhibiting the properties brought about by fluorine atoms, such as electrical properties and heat resistance, the fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72% to 76% by mass.

[0061] The surface tension of polymer F is preferably 16–26 mN / m. Furthermore, the surface tension of polymer F can be determined by placing droplets of a wetting index reagent (manufactured by Fujifilm and Wakamitsu Pharmaceutical Co., Ltd.) onto a plate made of polymer F.

[0062] Polymer F is preferably polytetrafluoroethylene (PTFE), polymers containing TFE units and ethylene-based units, polymers containing TFE units and propylene-based units, polymers containing TFE units and perfluoro(alkyl vinyl ether) (PAVE)-based units (PAVE units) (PFA), and polymers containing TFE units and hexafluoropropylene-based units (FEP). Polymers containing at least one of TFE units, PAVE units, and hexafluoropropylene-based units are more preferred. From the viewpoint of thermal conductivity, adhesion, processability, etc., PFA and FEP are further preferred, and PFA is more preferred. These polymers may also contain units based on other comonomers.

[0063] PAVE is preferably CF2=CFOCF3, CF2=CFOCF2CF3 and CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE"), and more preferably PPVE.

[0064] In particular, from the viewpoint of obtaining a liquid composition with high uniformity and dispersion, and also improving the adhesion of the resulting molded article, the F polymer preferably has oxygen-containing polar groups, more preferably has hydroxyl groups or carbonyl groups, and even more preferably has carbonyl groups.

[0065] The hydroxyl group is preferably an alcohol hydroxyl group, more preferably -CF2CH2OH and -C(CF3)2OH.

[0066] The carbonyl group is preferably a carboxyl group, alkoxycarbonyl group, amide group, isocyanate group, urethane group (-OC(O)NH2), acid anhydride residue (-C(O)OC(O)-), imide residue (-C(O)NHC(O)-, etc.) and carbonate group (-OC(O)O-), and more preferably an acid anhydride residue.

[0067] When polymer F contains carbonyl groups, the preferred number of carbonyl groups in polymer F is 1 × 10⁻⁶. 6 The number of carbon atoms in the main chain ranges from 10 to 5000, more preferably from 100 to 3000. Furthermore, the number of carbonyl groups in the F polymer can be quantified according to the polymer composition or the method described in International Publication No. 2020 / 145133.

[0068] The carbonyl group can be contained in the monomer-based unit of the F polymer or in the terminal group of the F polymer backbone, with the former being preferred. Examples of the latter include F polymers having carbonyl groups as terminal groups derived from polymerization initiators, chain transfer agents, etc., and F polymers obtained by plasma treatment or ionizing radiation treatment of F polymers.

[0069] Monomers containing carbonyl groups are preferably itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"), with NAH being more preferred.

[0070] The F polymer is preferably a polymer containing carbonyl groups, comprising TFE units and PAVE units, and more preferably a polymer comprising TFE units, PAVE units, and units based on monomers containing carbonyl groups, and comprising, in sequence, 90-99 mol%, 0.99-9.97 mol%, and 0.01-3 mol% of these units relative to all units. A specific example of such an F polymer is the polymer described in International Publication No. 2018 / 016644.

[0071] F particles are particles containing F polymer, preferably with F polymer as the main component, and more preferably composed of F polymer. F polymer as the main component means that, on a volume basis, the content of F polymer is relatively higher than that of other components.

[0072] From the viewpoint of dispersion stability, the D50 of the F particles is preferably 0.1 μm or more, more preferably greater than 0.3 μm, and even more preferably 1 μm or more. From the viewpoint of dispersion stability, the D50 of the F particles is preferably 25 μm or less, more preferably 10 μm or less, even more preferably 8 μm or less, and particularly preferably 5 μm or less.

[0073] The preferred specific surface area of ​​F particles is 1–50 m². 2 / g, preferably 1-25m 2 / g. The specific surface area of ​​F particles is more preferably greater than 6m². 2 / g, further optimized 7m 2 / g or more, with 8m being the preferred choice 2 / g or more. Furthermore, the specific surface area of ​​the F particles is preferably 25m². 2 Below / g. In this case, the above-mentioned mechanism of action is more easily manifested.

[0074] F particles can be used alone or in combination of two or more types. When two or more types of F particles are used in combination, different F particles refer to F particles with different average particle sizes, different types of F polymers, different contents of F polymers, different presence or absence of other components besides F polymers, different contents of other components, or different combinations of these.

[0075] The content of fluoride particles in the non-aqueous dispersion is preferably 10% by mass or more, more preferably 25% by mass or more. Furthermore, the content of fluoride particles in the non-aqueous dispersion is preferably 75% by mass or less, more preferably 60% by mass or less. If the content of fluoride particles in the non-aqueous dispersion is within the above range, the sedimentation of fluoride particles in the non-aqueous dispersion is easily suppressed, and the viscosity retention during storage is superior.

[0076] (Spherical BN particles)

[0077] The spherical BN particles are composed of boron nitride.

[0078] Whether boron nitride powder is spherical can be determined by observation with an electron microscope. In this disclosure, primary particles with an average sphericity of 0.8 or higher are called spherical BN particles.

[0079] The boron nitride purity of the spherical BN particles is preferably greater than 99% by mass, more preferably greater than 99.5% by mass. The upper limit of boron nitride purity is 100% by mass.

[0080] The crystal form of spherical BN particles can be any of the following: hexagonal, rhombohedral, cubic, or wurtzite.

[0081] The D50 of the spherical BN particles is less than 1 μm, preferably less than 0.8 μm, and more preferably less than 0.6 μm. From the viewpoint of suppressing aggregation, the D50 of the spherical BN particles is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.3 μm or more.

[0082] Spherical BN particles can partially agglomerate into secondary particles, but from the viewpoint of liquid stability, they are preferably primary particles. If spherical BN particles form secondary particles, since the particle size reaches 2 μm or more, the proportion of spherical BN particles with a particle size of 2 μm or more is preferably 1% or less, more preferably 0.9% or less, even more preferably 0.7% or less, and particularly preferably 0.5% or less.

[0083] The ratio of the D50 of F particles to the D50 of spherical BN particles (F particles / spherical BN particles) is preferably greater than 1, more preferably 2 or more, and even more preferably 3 or more. Furthermore, this ratio is preferably 10 or less, more preferably 6 or less.

[0084] If the above ratio is within the above numerical range, the affinity with F particles is easily enhanced, and sedimentation caused by the aggregation of F particles is easily suppressed. Furthermore, if the above ratio is within the above numerical range, spherical BN particles exist on the surface of F particles due to the affinity with F particles. As a result, the interaction with large-diameter inorganic particles is also easily manifested, thereby making it easier to manifest the excellent properties originally possessed by each particle in the formed article.

[0085] The specific surface area of ​​spherical BN particles is preferably 10 m². 2 / g or more, preferably 12m 2 / g or more. Furthermore, the specific surface area of ​​the spherical BN particles is preferably 50 m² / g or more. 2 / g or less, preferably 30m 2 Below / g, 20m is further preferred. 2 / g or less.

[0086] If the specific surface area of ​​the spherical BN particles is within the above-mentioned range, the affinity with F particles is easily enhanced, and the sedimentation of F particles and spherical BN particles in the liquid composition is easily suppressed. Therefore, the interaction with large-diameter inorganic particles is also easily manifested, resulting in the easy manifestation of the excellent properties originally possessed by each particle in the molded article.

[0087] The ratio of the specific surface area of ​​spherical BN particles to the specific surface area of ​​F particles is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less. Furthermore, this ratio is preferably 0.1 or more. In this case, the above-described mechanism of action is more easily manifested.

[0088] The total amount of Fe, Ca, Na, Mg and Al impurities in the spherical BN particles is preferably less than 50 ppm by mass, more preferably less than 30 ppm by mass, and even more preferably less than 10 ppm by mass.

[0089] Spherical BN particles can be manufactured or are commercially available.

[0090] The preferred method for manufacturing spherical BN particles includes: gas-phase synthesis in an inert gas stream using volatile borate alkoxide and ammonia as raw materials (stage 1), followed by calcination (stage 2), and further calcination of the calcined product (stage 3).

[0091] The preferred temperature for the first stage is 750–2200℃, and the preferred reaction time is less than 30 seconds. The preferred temperature for the second stage is 1000–1600℃, and the preferred reaction time is 1–10 hours. The preferred temperature for the third stage is 1800–2200℃, and the preferred reaction time is 0.5–8 hours.

[0092] The surface of spherical BN particles can be surface treated.

[0093] As surface treatment agents, examples include polyols (trimethylolethane, pentaerythritol, propylene glycol, etc.), saturated fatty acids (stearic acid, lauric acid, etc.), their esters, alkanolamines, amines (trimethylamine, triethylamine, etc.), paraffin wax, silane coupling agents, organosilicones, polysiloxanes, and inorganic substances (oxides, hydroxides, hydrated oxides, or phosphates of aluminum, silicon, zirconium, tin, titanium, antimony, etc.).

[0094] As a surface treatment agent, a silane coupling agent is preferred. In this case, the large-diameter inorganic particles have a greater affinity for the F polymer powder, and the dispersion stability of the dispersion is easily improved. The silane coupling agent preferably has an amino, mercapto, vinyl, acryloyloxy, or methacryloyloxy group.

[0095] The content of spherical BN particles in the liquid composition is preferably 0.5% by volume or more, more preferably 1% by volume or more, and even more preferably 2% by volume or more. Furthermore, the content of spherical BN particles in the liquid composition is preferably 20% by volume or less, more preferably 10% by volume or less.

[0096] (Large-diameter inorganic particles)

[0097] The D50 of the large-particle-size inorganic particles is greater than 1 μm, preferably 2 μm or more, more preferably 4 μm or more, and can be 10 μm or more. Furthermore, from the viewpoint of the homogeneous dispersibility of the liquid composition and the physical properties of the molded articles formed therefrom, the D50 of the large-particle-size inorganic particles is preferably 70 μm or less, more preferably 50 μm or less, and can be 20 μm or less, or 10 μm or less. More specifically, examples of the D50 morphology of the large-particle-size inorganic particles include morphologies with a D50 of 20–60 μm and morphologies with a D50 of 4–20 μm.

[0098] From the viewpoint of liquid stability, the ratio of D50 of large-diameter inorganic particles to D50 of spherical BN particles (large-diameter inorganic particles / spherical BN particles) is preferably 5 or more, more preferably 10 or more. Furthermore, from the viewpoint of liquid stability, this ratio is preferably 200 or less, more preferably 100 or less.

[0099] From the viewpoint of liquid stability, the ratio of the D50 of large-diameter inorganic particles to the D50 of F particles (large-diameter inorganic particles / F particles) is preferably greater than 1, more preferably 2 or more. Furthermore, from the viewpoint of liquid stability, this ratio is preferably 50 or less, more preferably 30 or less.

[0100] Large-diameter inorganic particles can be granular, needle-like (fibrous), or plate-like. Specific shapes of large-diameter inorganic particles include spherical, scaly, layered, leaf-like, almond-like, columnar, cockscomb-like, equiaxed, leaf-like, mica-like, blocky, plate-like, wedge-shaped, rosette-like, reticulate, and square columnar.

[0101] The preferred shape for large-diameter inorganic particles is flake-like or plate-like. If flake-like or plate-like large-diameter inorganic particles are used, they will form a cardboard box structure, which not only easily improves the liquid properties (viscosity, dispersion stability, etc.) of the dispersion, but also easily improves the orientation of the large-diameter inorganic particles in the molded product, thus easily improving its functions (mechanical strength, thermal conductivity, electrical properties, etc.).

[0102] The aspect ratio of the large-diameter inorganic particles is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, and particularly preferably 10 or more. The aspect ratio of the large-diameter inorganic particles is preferably 10000 or less. In this case, the orientation of the large-diameter inorganic particles in the molded article is easily further improved, and its function is easily enhanced. Specifically, not only is the dispersion state of the large-diameter inorganic particles in the dispersion liquid easily stabilized, but the orientation of the large-diameter inorganic particles is also further improved when the molded article is formed from the dispersion liquid, making it easy to obtain molded articles that highly possess both the physical properties of the F polymer and the physical properties of the large-diameter inorganic particles.

[0103] The material of the large-particle-size inorganic particles can be any inorganic material. Preferably, the large-particle-size inorganic particles include particles selected from at least one of oxides, nitrides, metal monomers, alloys, and carbon. One type of large-particle-size inorganic particle can be used alone, or two or more types can be used in combination.

[0104] Oxides that are large-particle inorganic particles can include silicon dioxide, magnesium oxide, aluminum oxide, etc., and can be composites such as mica, clay, talc, and glass.

[0105] Nitrides that are large-particle inorganic particles include boron nitride, silicon nitride, carbon nitride, and aluminum nitride.

[0106] Metal monomers that are large-particle inorganic particles include gold, silver, and copper.

[0107] Of the above, oxide particles or nitride particles are preferred as large-particle-size inorganic particles, silicon oxide particles, aluminum oxide particles or boron nitride particles are more preferred, boron nitride particles are even more preferred, and from the viewpoint of thermal conductivity, flake-shaped boron nitride particles (hereinafter also referred to as "flake-shaped BN particles") are particularly preferred. In this disclosure, particles with an average sphericity of less than 0.8 are called flake-shaped BN particles.

[0108] The boron nitride purity of the flake-like BN particles is preferably greater than 99% by mass, more preferably 99.5% by mass or more. The upper limit of boron nitride purity is 100% by mass. Boron nitride with this purity has excellent thermal conductivity, electrical properties, and other physical properties, but tends to have significantly reduced miscibility with F polymers. However, the liquid composition disclosed herein, due to the above-described structure and based on the above-described mechanism of action, exhibits excellent homogeneous dispersion, and the excellent physical properties originally possessed by the flake-like BN particles in the molded article are easily manifested.

[0109] The crystalline form of the flake-like BN particles can be hexagonal, rhombohedral, cubic, or wurtzite, with hexagonal being the preferred form.

[0110] From the viewpoint of the insulation properties of the molded article, the orientation index of the flake-shaped BN particles is preferably 15 or higher, and from the viewpoint of the thermal conductivity of the molded article, it is preferably 70 or lower.

[0111] In this disclosure, the orientation index of the scaly BN particles is determined by using an X-ray diffraction device in the range of 2θ = 10 to 70°, and the intensity I of the diffracted lines near 2θ = 27° [(002) plane] is calculated. 002 The intensity I of the diffraction lines near 2θ = 41° [(100) plane] 100 It can be calculated using the following formula.

[0112] Orientation Index = I 002 / I 100

[0113] In diffraction spectra, two types of diffraction lines are sometimes identified near 2θ = 27°: flaky BN particles and spherical BN particles. In this case, the sharp diffraction line on the high-angle side is used in this disclosure as the diffraction line corresponding to flaky BN particles.

[0114] Specific examples of flaky BN particles include the "UHP" series (manufactured by RESONAC Corporation), the "GP" and "HGP" grades of the "electrochemical boron nitride" series (manufactured by Denka Corporation).

[0115] The specific surface area of ​​large-diameter inorganic particles is preferably 1-20 m². 2 / g, more preferably 3-8m 2 / g. Under these conditions, large-diameter inorganic particles in the liquid composition are easily wetted, and the sedimentation of large-diameter inorganic particles in the liquid composition is easily suppressed. In addition, in the molded article, large-diameter inorganic particles are more uniformly dispersed (distributed), and the excellent physical properties originally possessed by large-diameter inorganic particles are easily manifested.

[0116] The surface of large-diameter inorganic particles can be treated. The surface treatment of large-diameter inorganic particles can refer to the surface treatment of spherical BN particles.

[0117] The content of large-diameter inorganic particles in the liquid composition is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more. Furthermore, the content of large-diameter inorganic particles in the liquid composition is preferably 40% by volume or less, more preferably 30% by volume or less, and even more preferably 20% by volume or less.

[0118] From the viewpoint of liquid stability, the ratio of the content of spherical BN particles to the content of large-diameter inorganic particles (spherical BN particles / large-diameter inorganic particles) is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more on a volume basis. Furthermore, from the viewpoint of liquid stability, this ratio is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.33 or less.

[0119] From the viewpoint of liquid stability, the ratio of the total amount of spherical BN particles and large-diameter inorganic particles to the content of F particles is preferably 50% by volume or more, more preferably 70% by volume or more, and even more preferably 80% by volume or more. Furthermore, from the viewpoint of liquid stability, this content is preferably 200% by volume or less, more preferably 150% by volume or less, and even more preferably 130% by volume or less.

[0120] (Liquid dispersion medium)

[0121] The liquid dispersion medium is a compound that is liquid at atmospheric pressure and 25°C, preferably a compound with a boiling point of 50–240°C. One or more liquid dispersion media can be used. When using two liquid dispersion media, they are preferably miscible.

[0122] The liquid dispersion medium is preferably selected from compounds in water, amides, ketones and esters.

[0123] Examples of amides include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, N,N-diethylformamide, hexamethylphosphoric triamine, and 1,3-dimethyl-2-imidazolinone.

[0124] Examples of ketones include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentanone, methyl isopentanone, 2-heptanone, cyclopentanone, cyclohexanone, and cycloheptanone.

[0125] 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.

[0126] The content of the liquid dispersion medium can be appropriately adjusted by considering factors such as the coating method and the thickness of the prepared molded article. For example, it is preferably 40% by volume or more, more preferably 60% by volume or more, relative to the total volume of the liquid composition. The content of the liquid dispersion medium is preferably 90% by volume or less, more preferably 80% by volume or less, relative to the total volume of the liquid composition.

[0127] The concentration of solid components in the liquid composition is preferably 20% by volume or more, more preferably 40% by volume or more, relative to the total volume of the liquid composition. The concentration of solid components is preferably 80% by volume or less. Furthermore, solid components refer to the total amount of substances forming solid components in the molded article formed from the liquid composition. Specifically, F particles, spherical BN particles, and large-diameter inorganic particles are considered solid components; if the liquid composition contains other resins, those other resins are also considered solid components.

[0128] (Other ingredients)

[0129] The liquid composition may incorporate particles of other fluoropolymers besides F polymers (hereinafter also referred to as "other F particles"). Examples of other fluoropolymers include hot-melt fluoropolymers other than F polymers and non-hot-melt fluoropolymers; from a formability viewpoint, hot-melt fluoropolymers other than F polymers are preferred. Hot-melt fluoropolymers other than F polymers are hot-melt fluoropolymers that do not contain TFE units.

[0130] When F particles are used in combination with other F particles, the proportion of the other F particles in the total amount of F particles and other F particles is preferably less than 50% by mass, more preferably less than 25% by mass. Furthermore, the above proportion is preferably more than 0.1% by mass, more preferably more than 1% by mass.

[0131] The liquid composition may contain resins other than fluoropolymers. Other resins may be included in the liquid composition in the form of powdered particles, or, if the liquid composition contains a liquid dispersion medium, may be included in the form of being dissolved or dispersed in the liquid dispersion medium.

[0132] Examples of other resins include polyester resins such as liquid crystal aromatic polyesters, imide resins, epoxy resins, maleimide resins, polyurethane resins, polyphenylene ether resins, polyphenylene ether resins, and polyphenylene sulfide resins. As other resins, aromatic polymers are preferred, and at least one aromatic imide polymer selected from aromatic polyimides, aromatic polyamic acids, aromatic polyamide imides, and precursors of aromatic polyamide imides is more preferred. In the liquid composition, the aromatic polymer is preferably included in the form of a varnish dissolved in a liquid dispersion medium.

[0133] Specific examples of aromatic imide polymers include the "UPIA-AT" series (manufactured by Ube Industries, Ltd.), the "Neopulim (registered trademark)" series (manufactured by Mitsubishi Gas Chemical Co., Ltd.), the "SPIXAREA (registered trademark)" series (manufactured by Somalon Corporation), the "Q-PILON (registered trademark)" series (manufactured by PI Technology Research Institute), the "WINGO" series (manufactured by WINGO Technology Co., Ltd.), the "Tohmide (registered trademark)" series (manufactured by Dick Toka Co., Ltd.), the "KPI-MX" series (manufactured by Kawamura Sangyo Co., Ltd.), "HPC-1000", and "HPC-2100D" (all manufactured by RESONAC Co., Ltd.).

[0134] When the liquid composition contains other resins, the volume ratio of the other resins to the total volume of F particles, spherical BN particles, and large-diameter inorganic particles is preferably 0.1% by volume or more, more preferably 1% by volume or more. The above ratio is preferably 15% by volume or less, more preferably 10% by volume or less.

[0135] From the viewpoint of further improving dispersion stability, the liquid composition may contain a surfactant. As a surfactant, a nonionic surfactant is preferred. Specific examples of nonionic surfactants include the "FTERGENT" series (manufactured by Neos Corporation), the "SURFLON" (registered trademark) series (manufactured by AGC Seimei Chemical Co., Ltd.), the "MEGAFACE" (registered trademark) 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 Bick Chemicals Japan Co., Ltd.). (manufactured by Japan), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Industry Co., Ltd.), and the "Tergitol" series ("Tergitol TMN-100X" manufactured by Dow Chemical Company, etc.).

[0136] When the liquid composition disclosed herein contains a surfactant, the surfactant content in the liquid composition is preferably 1 to 15% by volume.

[0137] From the viewpoint of further improving the miscibility of F polymer with spherical BN particles and large-diameter inorganic particles, the liquid composition may further contain silane coupling agents.

[0138] As silane coupling agents, the same types as those that can be used for the surface treatment of spherical BN particles and large-diameter inorganic particles can be listed, and their preferred range is also the same.

[0139] When the liquid composition contains a silane coupling agent, the content of the silane coupling agent in the liquid composition (except for those used for surface treatment of spherical BN particles and large-diameter inorganic particles) is preferably 1 to 10% of the total volume of the liquid composition.

[0140] The liquid composition may further contain thixotropic agents, viscosity modifiers, defoamers, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, surface treatment agents, flame retardants, conductive fillers, and other fillers and additives.

[0141] (Physical properties of liquid compositions)

[0142] The viscosity of the liquid composition at 25°C is preferably 10,000 mPa·s or less, more preferably 3,000 mPa·s or less. The viscosity of the liquid composition at 25°C is preferably 10 mPa·s or more, more preferably 100 mPa·s or more.

[0143] After storing the liquid composition in a container at 25°C for one month, the rate of change in viscosity before and after storage (hereinafter also referred to as "viscosity retention rate") expressed by the following formula is preferably 75% or more, more preferably 80% or more, further preferably 85% or more, and particularly preferably 90% or more.

[0144] Viscosity retention rate = Viscosity after storage (mPa·s) / Viscosity before storage (mPa·s) × 100

[0145] The thixotropic ratio of the liquid composition is preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less. Furthermore, the thixotropic ratio of the liquid composition is preferably 1 or more, more preferably 2 or more. If the thixotropic ratio of the liquid composition is within the above range, the sedimentation of particles containing hot-melt tetrafluoroethylene polymers, boron nitride particles, and inorganic particles is easily further suppressed.

[0146] When the liquid composition contains water as a liquid dispersion medium, a pH value of 8 to 10 is more preferable from the viewpoint of improving long-term shelf life. The pH value of such a liquid composition can be adjusted by a pH adjuster (amine, ammonia, citric acid, etc.) or a pH buffer (tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium bicarbonate, ammonium carbonate, ammonium acetate, etc.).

[0147] <Method for manufacturing liquid composition>

[0148] The liquid composition disclosed herein can be obtained by mixing F particles, spherical BN particles and large-diameter inorganic particles, as well as other resins, liquid dispersion media, surfactants, silane coupling agents, additives, etc., as needed. The mixing order is not particularly limited, and the mixing method can be either simultaneous mixing or multiple mixing steps.

[0149] From the viewpoint of obtaining a liquid composition with excellent stability in liquid properties, it is preferable to mix large-particle-size inorganic particles after mixing F particles, a liquid dispersion medium, and spherical BN particles (premixing). When the liquid composition is prepared in this mixing order, spherical BN particles easily adhere to the F particles, and sedimentation caused by the aggregation of F particles is easily suppressed. Furthermore, when the liquid composition is prepared in this mixing order, spherical BN particles are effectively present on the surface of the F particles, resulting in easier interaction with the large-particle-size inorganic particles, and the excellent properties originally possessed by each particle in the molded article formed from the liquid composition are easily manifested. In the premixing, the F particles, liquid dispersion medium, and spherical BN particles can be mixed together, or the F particles and liquid dispersion medium can be premixed and then the spherical BN particles are added.

[0150] Examples of mixing apparatuses for obtaining the liquid compositions disclosed herein include: agitators with blades such as Henschel mixers, pressure kneaders, Banbury mixers, and planetary mixers; pulverizers with media such as ball mills, pulverizers, basket mills, sand mills, sand grinders, DYNO mills, DISPERMAT dispersers, SC mills, Spike mills, and stirred mills; and dispersion apparatuses with other mechanisms such as microfluidizers, nano-dispersants, Ultimaizer dispersers, ultrasonic homogenizers, dissolvers, dispersers, high-speed impeller dispersers, thin-film gyratory high-speed mixers, rotary mixers, and V-type mixers.

[0151] <Uses of Liquid Compositions>

[0152] The uses of the liquid compositions disclosed herein are not particularly limited, for example, they can be used in the manufacture of molded articles. In particular, the liquid compositions disclosed herein are suitable for applications where it is desirable to exhibit the advantageous properties of the BN contained in the liquid composition.

[0153] Liquid compositions can be used as materials that impart insulation, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, thermal conductivity, etc.

[0154] Specifically, liquid compositions can be used in printed wiring boards, thermal interface materials, power module substrates, coils used in power devices such as motors, vehicle engines, heat exchangers, tubing, syringes, ampoules, medical wiring, secondary batteries such as lithium-ion batteries, primary batteries such as lithium batteries, free radical batteries, solar cells, fuel cells, lithium-ion capacitors, hybrid capacitors, capacitors, capacitors (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode adhesives, electrode diaphragms, electrodes (positive and negative electrodes), etc.

[0155] In addition, liquid compositions can also be used as adhesives for bonding components. Specifically, liquid compositions can be used for: bonding ceramic components, bonding metal components, bonding IC chips or electronic components such as resistors and capacitors on substrates of semiconductor elements or module components, bonding circuit boards to heat sinks, and bonding LED chips on substrates.

[0156] <Laminated bodies and methods for manufacturing laminated bodies>

[0157] The laminate disclosed herein comprises: a substrate, and a fluoropolymer layer disposed on the substrate containing F polymer, spherical BN particles and large-diameter inorganic particles.

[0158] The method for manufacturing the laminate disclosed herein involves applying the liquid composition disclosed herein onto a substrate, heating to remove the liquid dispersion medium, and further heating to melt and sinter the F particles.

[0159] Examples of substrates include: metal substrates (metal foils made of copper, nickel, aluminum, titanium, and alloys of these metals), heat-resistant resin films (heat-resistant resin films made of polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamide-imide, liquid crystal polyester, tetrafluoroethylene polymers, etc.), prepreg substrates (precursors to fiber-reinforced resin substrates), ceramic substrates (ceramic substrates made of silicon carbide, aluminum nitride, silicon nitride, etc.), and glass substrates.

[0160] The shapes of substrates can include planar, curved, and uneven. Furthermore, the properties of the substrate can be any of the following: foil, plate, film, and fibrous (woven fabric, nonwoven fabric, etc.).

[0161] The ten-point average roughness of the substrate surface is preferably 0.01 to 0.05 μm.

[0162] The substrate surface can be surface-treated with a silane coupling agent or subjected to plasma treatment. Examples of such silane coupling agents include those similar to those used for surface treatment of spherical BN particles and large-diameter inorganic particles.

[0163] The peel strength between the fluoropolymer layer and the substrate is preferably 10 N / cm or more, more preferably 15 N / cm or more. The peel strength is preferably 100 N / cm or less.

[0164] Methods for applying liquid compositions include coating, droplet spraying, and dipping, with roller coating, blade coating, bar coating, mold coating, or spraying being preferred.

[0165] Heating to remove the liquid dispersion medium is preferably performed at 100–200°C for 0.1–30 minutes. During this heating, the liquid dispersion medium does not need to be completely removed; it is sufficient to remove it to the point that the layer formed by the accumulation of F particles and composite particles can maintain a self-supporting film. Furthermore, air can be blown during heating to promote the removal of the liquid dispersion medium through air drying.

[0166] The heating during the firing of polymer F is preferably carried out at a temperature above the firing temperature of polymer F, and more preferably at 360 to 400°C for 0.1 to 30 minutes.

[0167] Examples of heating devices used in various heating processes include ovens and ventilated drying furnaces. The heat source in these devices can be a contact heat source (hot air, heating plate, etc.) or a non-contact heat source (infrared rays, etc.).

[0168] Furthermore, each heating can be performed under normal pressure or under reduced pressure.

[0169] In addition, the atmosphere in each heating process can be any of the following: air atmosphere or inert gas atmosphere (helium, neon, argon, nitrogen, etc.).

[0170] The fluoropolymer layer is formed through a process of applying a liquid composition and heating. These processes can be performed once or repeated more than once. For example, a liquid composition can be applied to a substrate surface and heated to form a fluoropolymer layer, followed by applying another liquid composition to the surface of the fluoropolymer layer and heating to form a second fluoropolymer layer. Alternatively, a liquid composition can be applied to the surface of the substrate and heated to remove the liquid dispersion medium, and then heated to form a fluoropolymer layer.

[0171] The liquid composition can be applied to only one surface of the substrate or to both surfaces of the substrate. The former yields a laminate having a substrate layer and a fluoropolymer layer on a single surface of the substrate layer, while the latter yields a laminate having a substrate layer and fluoropolymer layers on both surfaces of the substrate layer.

[0172] The thickness of the fluoropolymer layer can be appropriately selected according to the application; for example, it can be above 25 μm, above 30 μm, or above 40 μm. Furthermore, the thickness of the fluoropolymer layer can be below 200 μm.

[0173] The in-plane thermal conductivity of the fluoropolymer layer is preferably 1.0 W / (m·K) or higher, more preferably 3.0 W / (m·K) or higher. The upper limit of the thermal conductivity of the fluoropolymer layer is preferably 20 W / (m·K).

[0174] Suitable examples of laminates include metal-coated laminates having a metal foil and a fluoropolymer layer on at least one surface of the metal foil, and multilayer films having a polyimide film and fluoropolymer layers on both surfaces of the polyimide film.

[0175] Laminates formed from liquid compositions can be used as antenna components, printed circuit boards, aircraft components, automotive components, sports equipment, food industry supplies, heat dissipation components, etc.

[0176] Specifically, it can be used as a material for electrical wire sheathing (aircraft wires, etc.), enameled wire sheathing material for motors in electric vehicles, electrical insulating tape, insulating tape for oil drilling, oil pipelines, hydrogen tanks, materials for printed circuit boards, separation membranes (precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode adhesives (for lithium secondary batteries, fuel cells, etc.), photocopier rollers, covers for furniture, automotive dashboards, and household appliances, and sliding components (load bearings, yaw bearings, sliding shafts, valves, bearings). Bushings, seals, thrust washers, wear rings, pistons, slide switches, gears, cams, conveyor belts, food conveyor belts, tension ropes, wear pads, wear strips, tube lights, test sockets, wafer guides, wear parts of centrifugal pumps, chemical and water supply pumps, tools (shovels, files, chisels, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, racket strings, plastic molds, toilets, container covering materials, heat dissipation substrates for power devices, heat dissipation components for wireless communication devices, transistors, thyristors, rectifiers, transformers, power MOSFETs, CPUs, heat sinks, metal heat sinks, blades for windmills or wind power generation equipment or aircraft, casings for computers or monitors, electronic device materials, automotive interior and exterior trim, sealing materials for processing machines or vacuum furnaces that perform heat treatment under low oxygen conditions, plasma processing equipment, heat dissipation components in processing units of sputtering or various dry etching equipment, electromagnetic wave shielding, etc.

[0177] The laminate formed from the liquid composition of this disclosure can be used as electronic substrate materials such as flexible printed circuit boards and rigid printed circuit boards, protective films or heat dissipation substrates, especially heat dissipation substrates for automobiles.

[0178] Example

[0179] The following examples illustrate the implementation of this disclosure, but the implementation of this disclosure is not limited to these examples.

[0180] Prepare the following F particles.

[0181] F-particle 1: Each 1×10 of TFE units, NAH units, and PPVE units 6 Particles of tetrafluoroethylene polymers (melting temperature: 300℃) with 1000 carbonyl groups in the main chain (D50: 2.1μm, specific surface area: 8m²) 2 / g)

[0182] F-particle 2: Each 1×10 of TFE and PPVE units 6 Particles of tetrafluoroethylene polymers (melting temperature: 300℃) with 250 carbon atoms in the main chain and carbonyl groups (D50: 1.6μm, specific surface area: 16m²) 2 / g)

[0183] F-particle 3: Each 1×10 of TFE and PPVE units 6 Particles of tetrafluoroethylene polymers (melting temperature: 300℃) with 250 carbonyl groups in the main chain (D50: 3.6μm, specific surface area: 6m²) 2 / g)

[0184] (Example 1)

[0185] Prepare an aqueous dispersion containing 30% by mass of F particles 1, and add spherical BN particles (D50: 0.5 μm, specific surface area: 15 m²) to it. 2 / g), subjected to shearing and stirring treatment, and further added with flake-shaped BN particles (GP grade manufactured by Denka Co., Ltd. (D50: 7μm, specific surface area: 8m²)). 2 / g)), prepare aqueous liquid composition 1.

[0186] In this liquid composition 1, spherical BN particles are added to a volume of 3%, and flake BN particles are added to a volume of 15%. The content of F particles 1 in liquid composition 1 is 18% by volume. The ratio (by volume) of the content of spherical BN particles to the content of flake BN particles in liquid composition 1 is 0.2, and the ratio of the total content of flake BN particles and spherical BN particles to the content of F particles 1 is 100% by volume.

[0187] (Example 2)

[0188] Except for changing F particle 1 in Example 1 to F particle 2, the aqueous liquid composition 2 was prepared in the same manner as in Example 1.

[0189] (Example 3)

[0190] Except for changing F particle 1 in Example 1 to F particle 3, the aqueous liquid composition 3 was prepared in the same manner as in Example 1.

[0191] (Example 4)

[0192] By modifying the amount of each of the flake-like BN particles and spherical BN particles added in Example 2, a liquid composition 4 was obtained in which the ratio (by volume) of the content of spherical BN particles to the content of flake-like BN particles was 0.33, and the ratio of the total content of flake-like BN particles and spherical BN particles to the content of F particles 2 was 125% by volume.

[0193] (Example 5)

[0194] By modifying the amount of each of the flake-like BN particles and spherical BN particles added in Example 3, a liquid composition 5 was obtained in which the ratio (by volume) of the content of spherical BN particles to the content of flake-like BN particles was 0.33, and the ratio of the total content of flake-like BN particles and spherical BN particles to the content of F particles 3 was 125% by volume.

[0195] (Example 6)

[0196] The same method as in Example 1 was used, but without adding spherical BN particles, to prepare an aqueous liquid composition 6.

[0197] In addition, liquid compositions 1 to 6 are uniform and well-dispersed dispersions immediately after preparation.

[0198] <Evaluation>

[0199] (Evaluation of Settlement)

[0200] Each liquid composition was placed at 25°C for 3 days and visually observed, and evaluated according to the following evaluation criteria.

[0201] A: No sediment or floating matter was detected.

[0202] B: Settled matter has been identified, but floating matter has not been identified.

[0203] C: Settled and floating objects have been identified.

[0204] The evaluation results are summarized in Table 1 below.

[0205] [Table 1]

[0206] (Evaluation of thermal conductivity)

[0207] Liquid composition 1 or 6 is applied to the surface of a copper foil using a rod coating method to form a wet film. The copper foil with the wet film is then dried in a drying oven at 160°C for 5 minutes to form a dry film. The copper foil with the dry film is then heated in an oven under a nitrogen atmosphere at 350°C for 5 minutes. This produces laminates 1 and 6 having a copper foil and a fluoropolymer layer (100 μm thick) formed from liquid composition 1 or 6 on its surface.

[0208] Copper foil from laminates 1 and 6 was removed by etching with an aqueous ferric chloride solution to prepare sheets 1 and 6 with individual polymer layers. A 10 mm × 10 mm square test piece was cut from the center of the prepared sheet, and its in-plane thermal conductivity (W / (m·K)) was measured.

[0209] Sheet 1 prepared from liquid composition 1 has a higher thermal conductivity than sheet 6 prepared from liquid composition 6.

[0210] The disclosure of Japanese Patent Application No. 2023-131638 is incorporated herein by reference in its entirety. All documents, patent applications and technical specifications described herein are incorporated herein by reference to the extent that each document, patent application and technical specification is specifically and separately described therein.

Claims

1. A liquid composition comprising: particles containing a thermomeltable tetrafluoroethylene polymer, boron nitride spherical particles with an average particle size of less than 1 μm, inorganic particles with an average particle size of greater than 1 μm, and a liquid dispersion medium.

2. The liquid composition of claim 1, wherein, The hot-melt tetrafluoroethylene polymer comprises at least one of tetrafluoroethylene-based units, perfluoro(alkyl vinyl ether)-based units, and hexafluoropropylene-based units.

3. The liquid composition according to claim 1 or 2, wherein, The hot-melt tetrafluoroethylene polymer has a carbonyl group.

4. The liquid composition according to claim 1 or 2, wherein, The hot-melt tetrafluoroethylene polymer has a per 1×10 6 Each main chain has 10 to 5000 carbon atoms and contains carbonyl groups.

5. The liquid composition as described in claim 1 or 2, wherein, The specific surface area of ​​the particles of the hot-melt tetrafluoroethylene polymer is greater than 6m². 2 / g.

6. The liquid composition according to claim 1 or 2, wherein, The specific surface area of ​​the boron nitride spherical particles is 10 m². 2 / g or more.

7. The liquid composition according to claim 1 or 2, wherein, The ratio of the specific surface area of ​​the boron nitride spherical particles to the specific surface area of ​​the particles of the hot-melt tetrafluoroethylene polymer is less than 2.

0.

8. The liquid composition according to claim 1 or 2, wherein, The inorganic particles comprise at least one of the following: oxides, nitrides, metal monomers, alloys, and carbon.

9. The liquid composition according to claim 1 or 2, wherein, The total volume of the boron nitride spherical particles and the inorganic particles is 50 to 200 by volume relative to the content of the particles containing the hot-melt tetrafluoroethylene polymer.

10. The liquid composition according to claim 1 or 2, wherein, Based on volume, the ratio of the content of the boron nitride spherical particles to the content of the inorganic particles is 0.01 to 1.

11. The liquid composition according to claim 1 or 2, wherein, The liquid dispersion medium comprises at least one selected from water, ketones, amides, and esters.

12. A method for manufacturing the liquid composition according to claim 1 or 2, wherein after mixing the particles comprising a hot-melt tetrafluoroethylene polymer, a liquid dispersion medium, and the boron nitride particles with an average particle size of less than 1 μm, the inorganic particles with an average particle size of greater than 1 μm are mixed in.

13. A laminated body having: Substrate, and The fluororesin layer disposed on the substrate contains a hot-melt tetrafluoroethylene polymer, boron nitride spherical particles with an average particle size of less than 1 μm, and inorganic particles with an average particle size of greater than 1 μm.

14. A method for manufacturing a laminate, comprising applying the liquid composition of claim 1 or 2 onto a substrate, heating to remove the liquid dispersion medium, and further heating to melt and sinter the particles comprising a thermoplastic tetrafluoroethylene polymer.

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