WO2021241547A1

WO2021241547A1 - Method for producing dispersion

Info

Publication number: WO2021241547A1
Application number: PCT/JP2021/019727
Authority: WO
Inventors: 敦美山邊; 文伊藤
Original assignee: Ａｇｃ株式会社
Priority date: 2020-05-28
Filing date: 2021-05-25
Publication date: 2021-12-02
Also published as: TW202204486A; CN115667377A; JPWO2021241547A1

Abstract

[Problem] To provide: a method for producing a dispersion containing particles of a tetrafluoroethylene-based polymer, having excellent dispersion stability; and a method for producing composite particles obtained from said dispersion. [Solution] This method for producing a dispersion involves performing a shearing treatment on a liquid composition containing particles of a thermomeltable tetrafluoroethylene-based polymer, a filler of an inorganic compound, and a liquid polar dispersion medium, to obtain a dispersion containing the tetrafluoroethylene-based polymer, the filler of the inorganic compound, and the liquid dispersion medium.

Description

Dispersion liquid manufacturing method

The present invention relates to a method for producing a dispersion containing particles of a tetrafluoroethylene polymer and a filler of an inorganic compound, and a method for producing composite particles by such a method.

Tetrafluoroethylene-based polymers such as polytetrafluoroethylene (PTFE) have excellent physical properties such as electrical properties, water and oil repellency, chemical resistance, and heat resistance, and are used in various industrial applications such as printed circuit boards. There is. As a coating agent used to impart the physical properties to the surface of the base material, a dispersion liquid containing particles of a tetrafluoroethylene-based polymer is known.
In particular, in recent years, the frequency of signals has been increasing, and there is a demand for materials having electrical characteristics such as low dielectric constant and low dielectric loss tangent and excellent insulation performance. Therefore, as a material for forming a dielectric layer of a printed circuit board having excellent electrical characteristics such as low dielectric constant and low dielectric loss tangent and corresponding to frequencies in a high frequency band, a dispersion liquid containing particles of a tetrafluoroethylene polymer has attracted attention. There is.

Since the tetrafluoroethylene polymer has extremely low dispersion stability, various proposals have been made from the viewpoint of obtaining a dispersion liquid having excellent dispersion stability. Patent Document 1 discloses a dispersion liquid of PTFE particles further containing an inorganic filler of ceramics from the viewpoint of improving dispersion stability.

Japanese Unexamined Patent Publication No. 2016-194017

However, the dispersion stability of the dispersion described in Patent Document 1 is still insufficient. In addition, if high shear is applied during the preparation, foaming and aggregation in the dispersion are likely to occur due to air entrainment, alteration of the tetrafluoroethylene polymer, and the like. As a result, in the molded product obtained from such a dispersion liquid, the uniformity of the component distribution is likely to be lowered, and the water resistance is likely to be lowered due to the generation of voids.

As a result of diligent studies, the present inventors have preferably identified each component in a liquid composition containing predetermined tetrafluoroethylene polymer particles, an inorganic compound filler, and a polar liquid dispersion medium. It was found that when high shearing is applied by stirring or the like, a dispersion liquid having excellent dispersion stability can be obtained, and that the tetrafluoroethylene polymer is less likely to be deteriorated. Further, it was found that the molded product obtained from the dispersion liquid is dense and is particularly excellent in low dielectric loss tangent and low linear expansion coefficient.
An object of the present invention is to provide a method for producing a dispersion liquid having excellent dispersion stability and a method for producing composite particles constituting such a dispersion liquid.

The present invention has the following aspects.
[1] A liquid composition containing heat-meltable tetrafluoroethylene polymer particles, an inorganic compound filler, and a polar liquid dispersion medium is sheared to obtain the tetrafluoroethylene polymer and the inorganic compound filler. And a method for producing a dispersion liquid, which obtains a dispersion liquid containing the liquid dispersion medium.
[2] The tetrafluoroethylene-based polymer contains a unit based on perfluoro (alkyl vinyl ether) and has a polar functional group, and the tetrafluoroethylene-based polymer has 2 units based on perfluoro (alkyl vinyl ether) for all units. The production method according to [1], which is at least one selected from the group consisting of tetrafluoroethylene-based polymers containing 0.0 to 5.0 mol% and having no polar functional group.
[3] The method for producing [1] or [2], wherein the liquid dispersion medium is at least one selected from amides, ketones and esters.
[4] Any of [1] to [3], wherein the total content of the particles of the tetrafluoroethylene polymer and the filler of the inorganic compound is 40% by mass or more with respect to the total mass of the liquid composition. Manufacturing method.
[5] The mass ratio of the particles of the tetrafluoroethylene-based polymer to the filler of the inorganic compound in the liquid composition is 0.01 to 2.0, where the mass of the particles is 1 and the mass of the filler is 0.01 to 2.0. A manufacturing method according to any one of [1] to [4].
[6] The production method according to any one of [1] to [5], wherein the liquid composition contains 20 to 40% by mass of particles of the tetrafluoroethylene polymer and 5 to 40% by mass of a filler of the inorganic compound. ..
[7] The average particle size (volume-based cumulative 50% diameter) of the filler of the inorganic compound in the liquid composition is based on the average particle size (volume-based cumulative 50% diameter) of the particles of the tetrafluoroethylene-based polymer. The production method according to any one of [1] to [6], which is 0.0001 to 0.5.
[8] The production method according to any one of [1] to [7], which keeps the liquid temperature during the shearing treatment at 70 ° C. or lower.
[9] The production method according to any one of [1] to [8], which keeps the liquid viscosity during the shearing treatment at 100,000 mPa · s or less.
[10] The production method according to any one of [1] to [9], wherein the filler of the inorganic compound is a silica filler.
[11] The production method according to any one of [1] to [10], wherein the filler of the inorganic compound is surface-treated with a silane coupling agent.
[12] The production method according to any one of [1] to [11], wherein the liquid composition further contains a silane coupling agent.
[13] The production method according to any one of [1] to [12], which obtains a dispersion having a viscosity of 100,000 mPa · s or less.
[14] The production method according to any one of [1] to [13], which obtains a dispersion having a component sedimentation rate of 60% or more.
[15] A dispersion liquid is obtained by the production method according to any one of [1] to [14], and the liquid dispersion medium is further removed to contain the particles of the tetrafluoroethylene polymer and the composite particles containing the filler of the inorganic compound. A method for producing composite particles.

According to the present invention, it is possible to produce a dispersion liquid of a tetrafluoroethylene-based polymer having excellent dispersion stability. Further, from such a dispersion liquid, composite particles that contribute to the improvement of dispersion stability can be produced. The dispersion liquid produced by the method of the present invention is excellent in physical properties such as electrical characteristics, and is useful as a constituent material of a printed circuit board, for example. Further, the composite particles obtained from the dispersion liquid are also useful as additives and modifiers for various varnishes (resist, ink, paint, etc.).

The following terms have the following meanings.
The "average particle size (D50)" is a volume-based cumulative 50% diameter of an object (particle, filler) determined by a laser diffraction / scattering method. That is, the particle size distribution is measured by the laser diffraction / scattering method, the cumulative curve is obtained with the total volume of the group of objects as 100%, and the particle size is the point where the cumulative volume is 50% on the cumulative curve.
“D90” is the volume-based cumulative 90% diameter of the object, which is similarly measured.
The objects D50 and D90 are analyzed by a laser diffraction / scattering method using a laser diffraction / scattering type particle size distribution measuring device (LA-920 measuring instrument manufactured by HORIBA, Ltd.) after dispersing the object in water. Desired.
The "heat-meltable polymer" means a polymer exhibiting melt fluidity, and means a polymer having a temperature at which the melt flow rate is 0.1 to 1000 g / 10 minutes under the condition of a load of 49 N.
The "melting temperature" is the temperature corresponding to the maximum value of the melting peak of the polymer measured by the differential scanning calorimetry (DSC) method.
The "viscosity of the dispersion liquid" is a viscosity measured using a B-type viscometer under the condition of 25 ° C. and a rotation speed of 30 rpm. The measurement is repeated 3 times, and the average value of the measured values for 3 times is used.
The "thixotropic ratio" is a value calculated by dividing the _{viscosity η 1} of the dispersion liquid measured under the condition of a rotation speed of 30 rpm _{by the viscosity η 2} measured under the condition of a rotation speed of 60 rpm. The measurement of each viscosity is repeated 3 times, and the average value of the measured values for 3 times is used.
By "unit" in a polymer is meant an atomic group based on the monomer formed by the polymerization of the monomers. The unit may be a unit directly formed by a polymerization reaction, or may be a unit in which a part of the unit is converted into another structure by processing a polymer. Hereinafter, the unit based on the monomer a is also simply referred to as “monomer a unit”.

The production method of the present invention (hereinafter, also referred to as “this method”) is also referred to as particles (hereinafter, also referred to as “F powder”) of a heat-meltable tetrafluoroethylene polymer (hereinafter, also referred to as “F polymer”). ), A filler of an inorganic compound (hereinafter, also referred to as “inorganic filler”), and a liquid composition containing a polar liquid dispersion medium (hereinafter, also referred to as “dispersion medium”) are sheared to obtain the F powder. , A method for obtaining a dispersion containing the inorganic filler and the dispersion medium (hereinafter, also referred to as “the present dispersion”).

This dispersion has excellent dispersion stability. Further, when the dispersion liquid is air-dried on a glass plate and observed, composite particles in which the F powder and the inorganic filler are fused (hereinafter, also referred to as “main particles”. The inorganic filler adheres to the surface of the F powder). It was also confirmed for the first time that (including composite particles, etc.) existed.
The reason why the dispersion stability of the dispersion liquid is improved and the reason why the particles are formed, and their correlation and mechanism of action are not necessarily clear, but are estimated as follows, for example.
Compared to non-heat-meltable tetrafluoroethylene-based polymers, F-polymers are not only superior in shape stability such as fibril resistance, but also have a high degree of freedom in which restrictions on molecular motion are relaxed at the monomolecular level. Has a formation. Since such an F polymer tends to form microspherulites at the molecular aggregate level, fine uneven structures are likely to be formed on the surface thereof, and the surface area is likely to be large. Therefore, it is considered that the molecular aggregate of the F polymer, typically the F powder, can physically adhere closely to the inorganic filler to form the present particles while remaining stable without damaging its shape.
In addition, F powder has low surface energy and low dispersion stability, but the particles in which the inorganic filler with high dispersion stability and the F powder are fused are mutual with other particles and the liquid dispersion medium as compared with the F powder. Easy to work. As a result, it is considered that the particles have excellent dispersion stability.
As a result, since the particles have the physical characteristics of the F polymer and the physical characteristics of the inorganic filler and are excellent in stability, it is considered that a molded product having excellent electrical characteristics and the like could be formed from the dispersion liquid.

In this method, the D50 of the F powder is preferably 20 μm or less, more preferably 10 μm or less. The D50 of the F powder is preferably 0.01 μm or more, more preferably 0.1 μm or more. The D90 of the F powder is preferably 10 μm or less. In D50 and D90 in this range, the fluidity and dispersibility of the F powder become good, and the size of the composite particles existing in the dispersion liquid can be easily controlled so as to be difficult to settle.

In this method, the bulk density of the F powder ^{is preferably 0.15 g / m 2} or more, more preferably 0.20 g / m ² or more, from the viewpoint of the dispersion stability of the produced dispersion. The bulk density of the F powder is preferably 0.50 g / ^{m 2} or less, 0.35 g / ^{m 2} or less is more preferable.

In this method, the F powder may contain a resin other than the F polymer, but it is preferable that the F polymer is the main component. The content of the F polymer in the F powder is preferably 80% by mass or more, more preferably 100% by mass.
Examples of the resin include heat-resistant resins such as aromatic polyester, polyamide-imide, thermoplastic polyimide, polyphenylene ether, and polyphenylene oxide.

The F polymer in this method is a heat-meltable polymer containing a unit (TFE unit) based on tetrafluoroethylene (TFE). The melting temperature of the F polymer is preferably 260 to 325 ° C, more preferably 280 to 320 ° C. In such a case, the heat resistance of the molded product formed from the dispersion liquid obtained by the method of the present invention tends to be excellent.
The glass transition point of the F polymer is preferably 75 to 125 ° C, more preferably 80 to 100 ° C.
Examples of the F polymer include polymers (PFA) containing TFE units and units based on perfluoro (alkyl vinyl ether) (PAVE) (PAVE units), and polymers (FEP) containing units based on TFE units and hexafluoropropene (HFP). Therefore, it is preferably PFA. As the PAVE, CF ₂ = CFOCF ₃ , CF ₂ = CFOCF ₂ CF ₃ and CF ₂ = CFOCF ₂ CF ₂ CF ₃ (PPVE) are preferable, and PPVE is more preferable.

The F polymer preferably has a polar functional group. The polar functional group may be contained in a unit in the F polymer, or may be contained in the terminal group of the main chain of the polymer. In the latter aspect, an F polymer having a polar functional group as a terminal group derived from a polymerization initiator, a chain transfer agent, or the like, or an F polymer having a polar functional group obtained by subjecting the F polymer to plasma treatment or ionization line treatment can be used. Can be mentioned. As the polar functional group, a hydroxyl group-containing group, a carbonyl group-containing group and a phosphono group-containing group are preferable, and a hydroxyl group-containing group and a carbonyl group-containing group are more preferable from the viewpoint of dispersion stability of the dispersion produced by this method, and carbonyl. Group-containing groups are more preferred.
The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF ₂ CH ₂ OH, -C (CF ₃ ) ₂ OH and 1,2-glycol group (-CH (OH) CH ₂ OH). ..
The carbonyl group-containing group is a group containing a carbonyl group (> C (O)), a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC (O) NH ₂ ), and an acid anhydride residue. Groups (-C (O) OC (O)-), imide residues (-C (O) NHC (O)-etc.) and carbonate groups (-OC (O) O-) are preferred, and acid anhydride residues. Is more preferable.
When the F polymer has a carbonyl group-containing group, the number of carbonyl group-containing groups in the F polymer is preferably 10 to 5000, more preferably 100 to 3000, and more preferably 800 per ^{1 × 10 6 carbon atoms in the main chain.} ~ 1500 pieces are more preferable. The number of carbonyl group-containing groups in the F polymer can be quantified by the composition of the polymer or the method described in International Publication No. 2020/145133.

The F polymer comprises a polymer having a polar functional group (1) containing TFE units and PAVE units, or 2.0 to 5.0 mol% of PAVE units with respect to all units including TFE units and PAVE units. The polymer (2) having no polar functional group is preferable.
These F-polymers not only have excellent dispersion stability of the particles, but are also difficult to be denatured even when the shearing treatment is performed by this method, and in the molded product (polymer layer, etc.) obtained from the produced dispersion liquid, these F polymers are used. It is easy to distribute more densely and uniformly. Further, it is easy to form fine spherulites in the molded product, and it is easy to improve the adhesion with other components. As a result, it is easier to obtain a molded product having excellent various physical properties such as electrical characteristics.

The polymer (1) is preferably a polymer containing TFE units, PAVE units and units based on a monomer having a polar functional group, and 90 to 99 mol% of these units are used in this order with respect to all units, 0. More preferably, the polymer contains 5.5 to 9.97 mol% and 0.01 to 3 mol%. The presence of the polar functional group is preferable from the viewpoint of further improving the affinity and adhesion with the inorganic filler.
Further, as the monomer having a polar functional group, itaconic anhydride, citraconic anhydride or 5-norbornen-2,3-dicarboxylic acid anhydride (hereinafter, also referred to as “NAH”) is preferable.
Specific examples of the polymer (1) include the polymers described in International Publication No. 2018/16644.

The polymer (2) is composed of only TFE units and PAVE units, and preferably contains 95.0 to 98.0 mol% of TFE units and 2.0 to 5.0 mol% of PAVE units with respect to all the units. .. The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more, based on all the units.
Such a polymer has a higher degree of freedom in molecular conformation, and the above-mentioned mechanism of action is likely to be enhanced.
It should be noted that the polymer (2) does not have polar functional groups when the number of polar functional groups of the polymer is less than 500 with respect to ^{1 × 10 6 carbon atoms constituting the polymer main chain.} It means that there is. The number of the polar functional groups is preferably 100 or less, more preferably less than 50. The lower limit of the number of polar functional groups is usually 0.

The polymer (2) may be produced by using a polymerization initiator, a chain transfer agent, or the like that does not generate a polar functional group as the terminal group of the polymer chain, and is derived from an F polymer having a polar functional group (derived from the polymerization initiator). An F polymer or the like having a polar functional group at the terminal group of the main chain of the polymer) may be fluorinated to produce the polymer. Examples of the fluorination treatment method include a method using fluorine gas (see JP-A-2019-194314).

In this method, the inorganic filler is preferably particles of an inorganic compound.
Examples of the inorganic filler include fillers composed of oxides, nitrides, simple metals, alloys and carbon, and silicates (silicon oxide (silica), wollastonite, talc, mica) and metal oxides (oxidation). Fillers of beryllium, cerium oxide, aluminum oxide, soda alumina, magnesium oxide, zinc oxide, titanium oxide, etc.), boron nitride and magnesium metasilicate (steatite) are preferred, and are selected from aluminum, magnesium, silicon, titanium and zinc. Fillers of inorganic oxides containing at least one of the elements are more preferred, fillers of silica, titanium oxide, zinc oxide, steatite and boron nitride are even more preferred, and fillers of silica are particularly preferred. Further, the inorganic filler may be ceramics. As the inorganic filler, one kind may be used, or two or more kinds may be mixed and used. When two or more kinds of inorganic fillers are mixed and used, two kinds of silica fillers may be mixed and used, or a silica filler and a metal oxide filler may be mixed and used.

The inorganic filler easily interacts with the F polymer, easily withstands the shearing force even when the shearing treatment is performed in this method, and easily improves the dispersion stability of the obtained dispersion liquid. Further, in the molded product formed from the dispersion liquid (for example, the polymer layer and the film described later), the physical characteristics based on the inorganic filler are remarkably likely to be exhibited.

Above all, in this method, it is preferable that the inorganic filler contains silica. The content of silica in the inorganic filler is preferably 80% by mass or more, more preferably 90% by mass or more. The upper limit of the silica content is 100% by mass.

It is preferable that at least a part of the surface of the inorganic filler is surface-treated. Examples of the surface treatment agent used for such surface treatment include polyhydric alcohols (trimethylolethane, pentaeristol, propylene glycol, etc.), saturated fatty acids (stearic acid, lauric acid, etc.), esters thereof, alkanolamines, amines (trimethylamines, etc.). Triethylamine etc.), paraffin wax, silane coupling agent, silicone, polysiloxane, aluminum, silicon, zirconium, tin, titanium, antimony and other oxides, their hydroxides, their hydrated oxides, their phosphoric acid Salt is mentioned.

Above all, it is preferable that the inorganic filler is surface-treated with a silane coupling agent.
Examples of the silane coupling agent include 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane or 3-. Isocyanapropyltriethoxysilane is preferred.
In this method, it is most preferable to use a silica filler surface-treated with a silane coupling agent as the inorganic filler.

The specific surface area of the inorganic filler (BET method) is preferably 1 ~ ^20m 2 / g, more preferably 5 ~ ^8m 2 / g.

Specific examples of the inorganic filler include silica filler ("Admafine (registered trademark)" series manufactured by Admatex Co., Ltd.) and zinc oxide surface-treated with an ester such as propylene glycol dicaprate (manufactured by Sakai Chemical Industry Co., Ltd.). "FINEX (registered trademark)" series, etc.), spherical fused silica ("SFP (registered trademark)" series manufactured by Denka Co., Ltd., etc.), rutile-type titanium oxide coated with polyhydric alcohol and inorganic substances (manufactured by Ishihara Sangyo Co., Ltd.) "Typake (registered trademark)" series, etc.), rutile-type titanium oxide surface-treated with alkylsilane ("JMT (registered trademark)" series manufactured by Teika, etc.), hollow silica filler ("E" manufactured by Pacific Cement Co., Ltd.) -SPHERES "series, Nittetsu Mining Co., Ltd." Sirinax "series, Emerson & Cumming Co., Ltd." Ecocos Fire "series, Nippon Aerosil Co., Ltd. hydrophobic AEROSIL series" RX200 ", etc.), Tarkufiller (Nippon Tarku Co., Ltd.) "SG" series, etc.), Steatite filler ("BST" series, etc., manufactured by Nippon Tarku), Boron nitride filler ("UHP" series, manufactured by Showa Denko, "Dencaboron Nightride" series, manufactured by Denka. ("GP", "HGP" grade), etc.).

The shape of the inorganic filler includes granular, needle-like (fibrous), and plate-like, and specifically, spherical, scaly, layered, leaf-like, apricot kernel-like, columnar, chicken crown-like, equiaxed, and leaf-like. Examples include mica, block, flat plate, wedge, rosette, mesh, and prismatic. Of these, spherical and scaly are preferable, and spherical is more preferable.

The spherical inorganic filler is preferably substantially spherical. Approximately spherical means that when the inorganic filler is observed with a scanning electron microscope (SEM), the ratio of spherical particles having a ratio of the minor axis to the major axis of 0.5 or more is 95% or more. do. In the substantially spherical inorganic filler particles, the ratio of the minor axis to the major axis is preferably 0.6 or more, more preferably 0.8 or more. The above ratio is preferably less than 1. When such highly spherical inorganic filler particles are used, the inorganic filler and the F polymer are more uniformly distributed in the molded product (polymer layer or the like), and the physical properties of both are more likely to be expressed in a well-balanced manner.

The aspect ratio of the scaly inorganic filler is preferably 5 or more, more preferably 10 or more. The aspect ratio is preferably 1000 or less.
The average major axis (average value of the diameter in the longitudinal direction) of the scaly inorganic filler is preferably 1 μm or more, and more preferably 3 μm or more. The average major axis is preferably 20 μm or less, more preferably 10 μm or less. The average minor axis is preferably 0.01 μm or more, more preferably 0.1 μm or more. The average minor axis is preferably 1 μm or less, more preferably 0.5 μm or less. In this case, the inorganic filler and the F polymer are more uniformly distributed in the molded product (polymer layer or the like), and the physical properties of both are more likely to be balanced and expressed.

The scaly inorganic filler may have a single-layer structure or a multi-layer structure.
Examples of the latter inorganic filler include an inorganic filler having a hydrophobic layer on the surface and a hydrophilic layer inside. Specific examples thereof include an inorganic filler having a hydrophobic layer, a hydrophilic layer (moisture-containing layer), and a hydrophobic layer in this order. The water content of the hydrophilic layer is preferably 0.3% by mass or more. In this case, not only the dispersed state of the dispersion liquid produced by this method is easy to stabilize, but also the orientation of the inorganic filler in the molded product (polymer layer, etc.) is further enhanced, and the physical properties of the F polymer and the physical properties of the inorganic filler are highly enhanced. It is easy to obtain a molded product (polymer layer, etc.) provided in.

Further, the inorganic filler may be hollow. The average particle size (D50) of the hollow inorganic filler is preferably 0.01 μm or more, more preferably 0.1 μm or more. The average particle size is more preferably 10 μm or less, further preferably 5 μm or less. In such a case, in the molded product molded from the dispersion liquid produced by this method, the inorganic fillers are likely to be in contact with each other and filled, and the molded product is likely to have excellent electrical insulation.

The average pore diameter of the pores of the hollow inorganic filler is preferably 10 to 1000 nm, more preferably 50 to 100 nm. For the average pore diameter, the pore diameters of a plurality of pores (100) are obtained by direct observation with a scanning electron microscope (SEM) or the like, and the average value thereof is taken as the average pore diameter. In the case of irregularly shaped holes, the maximum diameter of the holes is the hole diameter.
The apparent specific gravity of the hollow inorganic filler is preferably 100 g / L or less, more preferably 30 to 60 g / L, from the viewpoint of sufficiently increasing the porosity. The apparent specific gravity of the hollow inorganic filler is obtained from the mass and volume of the inorganic filler when it is charged into a measuring cylinder (capacity: 250 mL).
As the hollow inorganic filler, a hollow silica filler is preferable.

The inorganic filler may be an isotropic filler or an anisotropic filler. The isotropic filler means a filler having the same physical properties (mechanical strength, electrical characteristics, thermal conductivity, etc.) regardless of the direction, and the anisotropic filler means a filler having different physical properties depending on the direction. ..

The average particle size (D50) of the inorganic filler is preferably 20 μm or less, more preferably 5 μm or less. The average particle size is preferably 0.001 μm or more, more preferably 0.01 μm or more.

When the inorganic filler is a mixture of two kinds of inorganic fillers, it is preferable that the average particle diameters of the two kinds of inorganic fillers are different from each other. In such a case, when the inorganic filler having a large average particle size is the inorganic filler (1) and the inorganic filler having a small average particle size is the inorganic filler (2), the average particle size of the inorganic filler (1) is the inorganic filler (2). The average particle size of the particles is preferably more than 1 times, more preferably 1.5 times or more. The average particle size of the inorganic filler (1) is preferably 10 times or less, more preferably 5 times or less the average particle size of the inorganic filler (2). Further, the mass ratio of the content of the inorganic filler (2) to the content of the inorganic filler (1) is preferably 1.5 times or more, and more preferably 2 times or more. The mass ratio is preferably 5 times or less.
In this case, the inorganic filler is less likely to be removed from the molded product formed from the present dispersion, and the surface of the molded product tends to be excellent in smoothness. In addition, the molded product tends to have excellent low dielectric loss tangent properties.

In this method, the polar liquid dispersion medium is preferably a compound that is liquid at 25 ° C., which is classified as polar under atmospheric pressure, and is at least one polar compound selected from amides, ketones and esters. Is more preferable.
It is considered that when such a dispersion medium is used, the inorganic filler alone does not have an excessive affinity in the liquid composition, and both the F powder and the inorganic filler can maintain a constant dispersed state. On the other hand, such a constant dispersed state can be said to be an unstable state that can be changed by an external stimulus. It is estimated that composite particles will be produced.
The boiling point of the dispersion medium is preferably in the range of 50 to 240 ° C. As the dispersion medium, one type may be used alone, or two or more types may be used in combination.

Dispersion media include water, N, N-dimethylformamide, N, N-dimethylacetamide, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, N-methyl-2. -Pyrrolidone, γ-butyrolactone, cyclohexanone, cyclopentanone, butyl acetate, methyl isopropyl ketone, methyl ethyl ketone can be mentioned.

When the dispersion medium is an aprotonic compound, the inorganic filler is a silane cup having at least a part of its surface having at least one group selected from the group consisting of an amino group, a vinyl group and a (meth) acryloyloxy group. It is preferably surface-treated with a ring agent, and more preferably surface-treated with phenylaminosilane. When the dispersion medium is a protonic compound such as water, it is preferable that the inorganic filler is not surface-treated.
The dispersion medium may contain a non-polar solvent as long as the effect of the present invention is not impaired. When the dispersion medium contains a non-polar solvent such as toluene, it is preferable that at least a part of the surface of the inorganic filler is hydrophobized, and at least one selected from the group consisting of an alkyl group and a phenyl group. It is preferably surface-treated with a silane coupling agent having a group.
In these combinations, the physical characteristics (dispersion stability, etc.) of the present dispersion are more likely to be improved.
In this method, the content of the dispersion medium in the liquid composition is preferably 30 to 90% by mass, more preferably 50 to 80% by mass.

In this method, the total content of the F powder and the inorganic filler in the liquid composition is preferably 40% by mass or more, more preferably 50 to 80% by mass, based on the total mass of the liquid composition.
Further, the mass ratio of the F powder to the inorganic filler in the liquid composition is preferably 0.01 to 2.0, with the mass of the F powder being 1. From the viewpoint that a molded product such as a layer can be suitably formed from the dispersion liquid produced by this method, the liquid composition preferably contains 20 to 40% by mass of F powder and 5 to 40% by mass of an inorganic filler.

The liquid composition can be prepared by mixing F powder, an inorganic filler and a dispersion medium. As a mixing method, the F powder and the inorganic filler are collectively added to the dispersion medium and mixed; the F powder and the inorganic filler are sequentially added to the dispersion medium and mixed; the F powder and the inorganic filler are mixed in advance. Then, a method of mixing the obtained mixture and the dispersion medium; a method of premixing the F powder and the dispersion medium, a method of premixing the inorganic filler and the dispersion medium, and further mixing the two obtained mixtures; and the like can be mentioned. In this method, the liquid composition is prepared by a procedure in which F powder is dispersed in a dispersion medium in advance, and then particles of an inorganic filler are added as they are (directly) or in a state of being dispersed in a dispersion medium and mixed. After the particles of the inorganic filler are dispersed in the dispersion medium in advance, the liquid composition is prepared by adding the F powder as it is (directly) or in the state of being dispersed in the dispersion medium and mixing them. It is advantageous and preferable from the viewpoint of mixing the powder and the particles of the inorganic filler and dispersing them more uniformly.
When a silane coupling agent, a surfactant or another resin material, which will be described later, is further contained in the liquid composition, the F powder is added at the same time as the dispersion medium in advance, or the F powder is dispersed. It is preferable to add it to the previous dispersion medium in advance.

Examples of the method of shearing the liquid composition include a stirring device equipped with blades (stirring blades) such as propeller blades, turbine blades, paddle blades, and shell-shaped blades in a single axis or multiple axes, a henshell mixer, and a pressurized kneader. , Turbine mixer or planetary mixer; ball mill, attritor, basket mill, sand mill, sand grinder, dyno mill (bead mill using crushing medium such as glass beads or zirconium oxide beads), dispermat, SC mill, spike mill or Mixing with a disperser using media such as an agitator mill; using a disperser that does not use media such as high-pressure homogenizers such as microfluidizers, nanomizers, and ultimateizers, ultrasonic homogenizers, resolvers, dispersers, and high-speed impeller dispersers. Mixing is included.

The shearing process is preferably under high shear conditions. "High shear" means, in the case of agitation, agitation at a rate greater than at least 300 rpm.
The shearing treatment may be started during the addition of the particles of the inorganic filler to the liquid composition containing the F powder, or may be performed after the addition is completed. By continuously performing these shearing treatments for a sufficient time, a dispersion liquid having excellent dispersion stability can be formed.

The liquid temperature of the liquid composition containing F powder during the shearing treatment is preferably kept at 70 ° C. or lower, more preferably 50 ° C. or lower. When the liquid temperature is maintained at such a temperature, the obtained dispersion is difficult to thicken and gel. In addition, the particles are easily formed, and the obtained dispersion is likely to have excellent dispersion stability. The liquid temperature is preferably maintained above 0 ° C., more preferably above 10 ° C.
Further, the liquid viscosity of the liquid composition containing F powder during the shearing treatment is preferably kept at 100,000 mPa · s or less, and from the viewpoint of obtaining a dispersion liquid having excellent dispersion stability, it is kept at 10,000 mPa · s or less. Is more preferable. The liquid viscosity of the liquid composition during the shearing treatment is preferably 1 mPa · s or more, and more preferably 10 mPa · s or more.

The flow form of the liquid composition in the shearing treatment is preferably an ascending flow. The ascending flow may be an ascending flow in any of a swirling flow, a vertical circulation flow, and a radiating flow. Further, when forming the ascending flow, the flow form may be adjusted by a baffle plate or the like, or the flow form may be eccentric by adjusting the installation position and the installation angle of the processing device (stirring machine, stirring tank, etc.).
When the liquid composition is sheared by forming an ascending flow, the interaction between the F powder and the inorganic filler during the shearing process proceeds uniformly, and the dispersion stability of the present dispersion is more likely to be improved.

In this method, the liquid composition may further contain a silane coupling agent. When the liquid composition contains a silane coupling agent, the F powder and the inorganic filler are more firmly bonded to each other, making it easier to obtain the particles in which the F powder or the inorganic filler is less likely to be removed, resulting in dispersion stability. It is easy to obtain an excellent dispersion. Examples of the silane coupling agent include compounds similar to those of the above-mentioned silane coupling agent, which can be used in the surface treatment of the inorganic filler.
When the liquid composition further contains a silane coupling agent, the content thereof is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 1% by mass or more. The content is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less.
The ratio of the content of the silane coupling agent to the content of the F powder in the liquid composition is preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.05 or more. The above ratio is preferably 0.3 or less, more preferably 0.1 or less.
When the content of the silane coupling agent or the above ratio (mass ratio) is within such a range, the above-mentioned mechanism of action is further enhanced, and the present dispersion having excellent dispersion stability and the like can be easily obtained.

In this method, the liquid composition may or may not further contain a surfactant.
When the liquid composition contains a surfactant, the content thereof is preferably 1 to 15% by mass, and the surfactant is preferably nonionic.
The hydrophilic moiety of the surfactant preferably has an oxyalkylene group or an alcoholic hydroxyl group. The hydrophobic moiety of the surfactant preferably has an acetylene group, a polysiloxane group, a perfluoroalkyl group or a perfluoroalkenyl group.
As the surfactant, a glycol-based surfactant, an acetylene-based surfactant, a silicone-based surfactant or a fluorine-based surfactant is preferable, and a silicone-based surfactant is more preferable. As the nonionic surfactant, one kind may be used, or two or more kinds may be used. When two kinds of nonionic surfactants are used, the nonionic surfactants are preferably a silicone-based surfactant and a glycol-based surfactant.
Specific examples of such surfactants include "Futergent" series (manufactured by Neos), "Surflon" series (manufactured by AGC Seimi Chemical), "Megafuck" series (manufactured by DIC), and "Unidyne" series (Daikin). (Made by Kogyo Co., Ltd.), "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", "BYK-3456" (Big Chemie Japan) , "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), "Tergitol" series (manufactured by Dow Chemical Corporation, "Tergitol TMN-100X", etc.).
However, according to this method, according to the above-mentioned mechanism of action, it is possible to produce the present dispersion liquid having excellent dispersion stability and handleability without necessarily using a surfactant. In addition, the low dielectric loss tangent property of the molded product formed from the present dispersion liquid containing no surfactant is likely to be further improved.

In this method, from the viewpoint of improving the adhesiveness and low linear expansion property of the molded product formed from the present dispersion, the liquid composition may further contain a resin material other than the F polymer. Such a resin material may be thermosetting or thermoplastic, may be modified, may be dissolved in the liquid composition and the present dispersion, or may not be dissolved and dispersed. good.
Examples of such resin materials include tetrafluoroethylene polymers other than F polymers, aromatic polyimides, aromatic polyamic acids which are aromatic polyimide precursors, aromatic maleimides, acrylic resins, phenol resins, liquid crystal polyesters, and liquid crystal polyester amides. , Polyimide resin, modified polyphenylene ether, polyfunctional cyanic acid ester resin, polyfunctional maleimide-cyanic acid ester resin, polyfunctional maleimide, aromatic elastomers such as styrene elastomer, vinyl ester resin, urea resin, diallyl phthalate resin, melamine. Resin, guanamine resin, melamine-urea cocondensation resin, polycarbonate, polyarylate, polysulfone, polyallylsulfone, aromatic polyamide, aromatic polyetheramide, polyphenylene sulphide, polyallyl ether ketone, polyamideimide, polyphenylene ether, epoxy resin. And so on. As the tetrafluoroethylene-based polymer other than the F polymer, polytetrafluoroethylene is preferable.

In this method, the liquid composition preferably further contains an aromatic polymer. The aromatic polymer is preferably aromatic polyimide, aromatic polyamideimide, aromatic maleimide, polyphenylene ether, aromatic polyamic acid, or aromatic elastomer (styrene elastomer or the like), and is a thermoplastic aromatic polyimide. Is more preferable.
In this case, not only the adhesiveness and low linear expansion property of the molded product formed from the present dispersion are further improved, but also the liquid properties (viscosity, thixotropic ratio, etc.) of the present dispersion are balanced, and the handling property is improved. Easy to improve.
Here, examples of the styrene elastomer include copolymers of styrene and conjugated diene or (meth) acrylic acid esters (styrene-butadiene rubber, styrene-based core-shell type copolymers, styrene-based block copolymers, etc.), and rubber and plastic. Styrene elastomers having both properties, which are plasticized by heating and exhibit flexibility, are preferred.
From the viewpoint of improving the electrical properties of the molded product formed from the present dispersion, it is preferable that the resin material is a tetrafluoroethylene polymer other than the F polymer.

When the liquid composition contains a resin material, the content thereof is preferably 40% by mass or less with respect to the entire liquid composition.

In addition to the above components, the dispersion liquid produced by this method has a thixotropic agent, a viscosity modifier, a defoaming agent, a dehydrating agent, a plasticizer, a weather resistant agent, and an oxidation, as long as the effects of the present invention are not impaired. Other components such as inhibitors, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, flame retardants, and various fillers may be further contained.

The D50 of the composite particles (main particles) present in the present dispersion is preferably 20 μm or less, more preferably 15 μm or less. The D50 of the particles is preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more.
The D90 of the present particles is preferably 30 μm or less, more preferably 20 μm or less.
When D50 and D90 of the present particles are within such a range, the dispersion stability of the present particles in the present dispersion liquid and the physical properties of the molded product (polymer layer or the like) obtained from the present dispersion liquid are more likely to be improved.

As an embodiment of the composite particles (main particles) present in the present dispersion, an F polymer particle (F powder) is used as a core, and an inorganic filler is attached to the surface of the core (hereinafter, “Aspect I”). Also referred to as), there is an embodiment in which an inorganic filler is used as a core and F powder is adhered to the surface of the core (hereinafter, also referred to as “Aspect II”), and the particles of Aspect I are preferable.

Here, the "core" means a core (central part) necessary for forming the particle shape of the composite particle, and does not mean the main component in the composition of the composite particle.
The deposit (inorganic filler or F powder) adhering to the surface of the core may be adhered only to a part of the surface of the core, or may be attached to most or the entire surface thereof. In the former case, it can be said that the deposits cling to the surface of the core like dust, in other words, a large part of the surface of the core is exposed. In the latter case, it can be said that the deposits are evenly sprinkled on the surface of the core or are in a state of covering the surface of the core, and such composite particles are formed from the core and the shell covering the core. It can be said that it has a core-shell structure.

In the case of the aspect I, in the composite particles, an inorganic filler having a hardness higher than that of the F polymer and having high dispersion stability is exposed on the surface. As a result, the F polymer is less likely to be denatured, and the fluidity of the composite particles and their handleability are likely to be improved. In addition, the dispersion stability of the composite particles tends to increase.
The core of the F powder and the inorganic filler are preferably in the form of particles, respectively. In the case of the aspect I, the core of the F powder may be composed of a single particle of the F powder or an aggregate of the F powder.
For the composite particles of aspect I, it is preferable that the D50 of the F powder is set to be larger than the D50 of the particles of the inorganic filler, and the amount of the F powder is set to be larger than the amount of the particles of the inorganic filler. If the dispersion liquid is produced by the method of the present invention with such a relationship set, it is easy to obtain the composite particles of the aspect I.

In the case of the aspect I, the D50 of the particles of the inorganic filler is preferably 0.0001 to 0.5, more preferably 0.01 to 0.3, based on the D50 of the F powder. Specifically, it is preferable that the D50 of the F powder is more than 1 μm and the D50 of the particles of the inorganic filler is 0.1 μm or less. The amount of particles of the inorganic filler is preferably 0.1 part by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of F powder. The upper limit is preferably 50 parts by mass, more preferably 25 parts by mass, and even more preferably 5 parts by mass.
In the composite particles of the aspect I thus obtained, the above relationship is maintained, the D50 of the core of the F powder is larger than the D50 of the particles of the inorganic filler, and the mass of the F polymer occupying the same is larger than the mass of the inorganic filler. Will increase. In this case, the surface of the core of the F powder is covered with a larger amount of particles of the inorganic filler, and the composite particles of the aspect I have a core-shell structure. Further, in this case, the aggregation of the F powder particles is suppressed, and it is easy to obtain composite particles (main particles) in which the particles of the inorganic filler are attached to the core composed of the single F powder particles.

In the aspect I, the inorganic filler is preferably spherical particles, more preferably substantially spherical particles. In such a case, the dispersibility stability of the obtained composite particles tends to increase. In the particles of the substantially spherical inorganic filler, the ratio of the minor axis to the major axis is preferably 0.5 or more, more preferably 0.8 or more. The above ratio is preferably less than 1. Here, the "sphere" includes not only a true sphere but also a slightly distorted sphere.
When such highly spherical inorganic filler particles are used, the inorganic filler and the F polymer are more uniformly distributed in the molded product (polymer layer or the like), and the physical properties of both are more likely to be expressed in a well-balanced manner.

In the aspect I, the average particle size (D50) of the particles of the inorganic filler is preferably in the range of 0.001 to 0.3 μm, more preferably 0.005 to 0.2 μm, still more preferably 0.01 to 0.1 μm. When the average particle size (D50) is within such a range, the handleability and fluidity of the composite particles are likely to be improved, and the dispersion stability is likely to be improved.
Further, the particle size distribution of the particles of the inorganic filler is preferably 3 or less, and more preferably 2.9 or less, using the value of D90 / D10 as an index. Here, "D10" is a volume-based cumulative 10% diameter of the object, which is measured in the same manner as D50 and D90. In such a case, it is easy to control the fluidity of the obtained composite particles.

In the aspect I, it is preferable that at least a part of the surface of the particles of the inorganic filler is surface-treated, and it is more preferable that the particles are surface-treated with a silazane compound such as hexamethyldisilazane, a silane coupling agent, or the like. preferable. Examples of the silane coupling agent include the above-mentioned compounds.

In the aspect I, one kind of inorganic filler particles may be used, or two or more kinds of particles may be mixed and used. When the particles of the two kinds of inorganic fillers are mixed and used, the average particle diameter of each inorganic filler may be different from each other, and the mass ratio of the content of each inorganic filler can be appropriately set according to the desired function.

In the composite particles of aspect I, the D50 of the core of the F powder is preferably 0.1 μm or more, more preferably more than 1 μm. The upper limit is preferably 100 μm, more preferably 50 μm, and even more preferably 10 μm. The D50 of the particles of the inorganic filler is preferably 0.001 μm or more, more preferably 0.01 μm or more. The upper limit is preferably 1 μm, more preferably 0.1 μm.
Further, the ratio of the F polymer to the composite particles of the aspect I is preferably 50 to 99% by mass, more preferably 75 to 99% by mass. The proportion of the inorganic filler is preferably 1 to 50% by mass, more preferably 1 to 25% by mass.

The composite particles of Aspect I may be further surface-treated depending on the physical properties of the inorganic filler adhering to the surface. Specific examples of such surface treatment include a method of surface-treating the composite particles of Embodiment I with siloxanes (polydimethylsiloxane or the like) or a silane coupling agent.
Such surface treatment can be carried out by mixing the dispersion liquid in which the composite particles are dispersed with the siloxanes or the silane coupling agent, reacting the siloxanes or the silane coupling agent, and recovering the composite particles. As the silane coupling agent, the above-mentioned silane coupling agent having a functional group is preferable.
According to such a method, the surface physical characteristics of the composite particles can be further adjusted.

In the case of Aspect II, the core of the inorganic filler is preferably in the form of particles. In this case, in the composite particles, the surface of the core of the inorganic filler is easily covered with the F powder. The core of the inorganic filler may be composed of a single particle of the inorganic filler or may be composed of an aggregate of the inorganic filler.

For the composite particles of the aspect II, it is preferable to set the D50 of the particles of the inorganic filler to be larger than the D50 of the F powder, and to set the amount of the particles of the inorganic filler to be larger than the amount of the F powder. If the dispersion is produced by the method of the present invention with such a relationship set, it is easy to obtain the composite particles of the second aspect.
In the case of Aspect II, the D50 of the F powder is preferably 0.0001 to 0.5, more preferably 0.01 to 0.3, based on the D50 of the particles of the inorganic filler.
The amount of F powder is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the particles of the inorganic filler. The upper limit is preferably 50 parts by mass, more preferably 10 parts by mass.
In the composite particles of the aspect II thus obtained, the above relationship is maintained, the D50 of the core of the inorganic filler is larger than the D50 of the F powder, and the mass of the inorganic filler occupying the D50 is larger than the mass of the F polymer. .. In this case, the surface of the core of the inorganic filler is coated with a larger amount of F powder so that the composite particles of aspect II have a core-shell structure.

In the composite particles of Aspect II, the D50 of the core of the inorganic filler is preferably 0.1 μm or more, more preferably more than 1 μm. The upper limit is preferably 30 μm, more preferably 10 μm. The proportion of the inorganic filler in the composite particles of Embodiment II is preferably 50 to 99% by mass, more preferably 60 to 90% by mass. The proportion of the F polymer is preferably 1 to 50% by mass, more preferably 10 to 40% by mass.

As a means for removing the dispersion medium from the dispersion liquid and isolating the particles, it is preferable to use heating, depressurization or filtration. These means may be used in combination as appropriate.
Specific examples of the means for isolating the particles include (1) distilling off the dispersion medium under atmospheric pressure or reduced pressure to concentrate, filtering and drying as necessary; (2) controlling the temperature of the dispersion. While the particles are agglomerated, or after coagulation / crystallization by adding an electrolyte, a coagulant, a coagulation aid, etc., they are separated and dried by filtration or the like; (3) The dispersion medium can volatilize the dispersion. It is sprayed into a dry gas having a temperature to be dried and recovered; (4) the dispersion is centrifuged and then dried.
Here, examples of the drying means include vacuum drying, high frequency drying, and hot air drying.
In each of the above means (1) to (4), if necessary, the dispersion may be diluted with a dispersion medium to adjust the total content of the F polymer and the inorganic filler in the dispersion in advance.

In the above means (1), a method in which the dispersion liquid is frozen and then the dispersion medium is preferably sublimated and removed under a reduced pressure atmosphere to obtain the composite particles is more preferable.
Freezing is preferably performed at a temperature lower than 0 ° C. Specifically, it is preferable to expose the dispersion liquid to an atmosphere at a temperature equal to or lower than the melting point of the dispersion medium used, for example, −100 to −10 ° C., and freeze it. Freezing is preferably completed within 8 hours from the viewpoint of suppressing the sedimentation of the components of the dispersion liquid. Further, from the viewpoint of suppressing non-uniformity of the frozen product due to rapid freezing, it is preferable to freeze the dispersion liquid for 10 minutes or more.
The removal of the dispersion medium from the frozen dispersion (frozen product) by sublimation may be performed under conditions in which the dispersion is suppressed from melting. The temperature at which the dispersion medium is sublimated is preferably less than 0 ° C., specifically, the frozen product is preferably exposed to an atmosphere of −100 to 0 ° C. The pressure for sublimation is usually a reduced pressure atmosphere, preferably a reduced pressure atmosphere of ^{0 to 1 × 10 2 Pa.} The time for sublimating the dispersion medium is usually 4 to 72 hours.
Examples of the device used for sublimation include a centrifuge, a shelf dryer and the like.

In the above means (2), examples of the electrolyte include inorganic salts such as potassium nitrate, sodium nitrate, sodium carbonate, and sodium hydrogen carbonate. Examples of the coagulant or coagulation aid include nitrate, hydrochloric acid, sulfuric acid, magnesium chloride, calcium chloride, sodium chloride, aluminum sulfate, magnesium sulfate and barium sulfate.
Further, the dispersion liquid may be agitated at the time of coagulation / crystallization to adjust the polymer content and pH of the dispersion liquid, or a pH adjuster and an organic solvent may be added to the dispersion liquid. Examples of the pH adjusting agent include sodium carbonate, sodium hydrogencarbonate, ammonia, ammonium salts, and urea. Examples of the organic solvent include alcohol and acetone.
In the above means (2), when the composite particles are coagulated and separated from the dispersion medium by filtration or the like, the composite particles in a wet state are obtained, and when this is dried, the composite particles are obtained. The drying temperature is preferably 110 to 250 ° C.

The above means (3) is preferably performed by spraying the dispersion liquid in an atmosphere at a temperature at which the dispersion medium sufficiently volatilizes. Specifically, a method of spraying the dispersion liquid vertically on a system in which an inert gas such as nitrogen gas having a temperature of more than 100 ° C. is circulated above the vertical direction and drying the mixture is preferable. An apparatus such as a crystallization tower can be used for such a method.

The particles can be stably dispersed even if a large amount is added to the liquid dispersion medium. Further, in the molded product (polymer layer, film, etc.) formed from the liquid composition, the F polymer and the inorganic filler are more uniformly distributed, and the physical properties (electrical characteristics, adhesiveness, etc.) of the F polymer and the inorganic filler are obtained. (Low line swelling, etc.) is highly likely to occur.

The viscosity of the dispersion liquid produced by this method is preferably 50 mPa · s or more, more preferably 100 mPa · s or more, further preferably 5000 mPa · s or more, and particularly preferably 10,000 mPa · s or more. The viscosity of this dispersion is preferably 100,000 mPa · s or less, more preferably 50,000 mPa · s or less, and even more preferably 20,000 mPa · s or less. In this case, the present dispersion has excellent coatability and easily forms a molded product (polymer layer or the like) having an arbitrary thickness.
Further, in the present dispersion having a viscosity in such a range, particularly in a high viscosity range, the inorganic filler is less likely to aggregate and is easily uniformly distributed in the molded product formed from the dispersion, so that the physical characteristics of the F polymer and the inorganic filler are different. It is highly balanced and easy to develop.
The viscosity of the dispersion liquid produced by this method is preferably 50 mPa · s or more, and more preferably 100 mPa · s or more. The viscosity of this dispersion is preferably 100,000 mPa · s or less, more preferably 10,000 mPa · s, and even more preferably 1000 mPa · s or less. In this case, the present dispersion is preferable because it has excellent dispersion stability.
Further, for example, when the inorganic filler is a non-spherical anisotropic filler, its dispersion stability is more likely to be improved by the above-mentioned mechanism of action. Further, in a molded product such as a coating film formed from the present dispersion liquid, the inorganic filler tends to be randomly oriented and the physical properties tend to be the same regardless of the direction. For example, it is easy to obtain a layer or film whose mechanical strength and electrical characteristics are equivalent in the plane direction and the vertical direction of the layer or film.
The viscosity of this dispersion may be adjusted by further mixing a liquid dispersion medium after shearing treatment.

The thixotropic ratio of the dispersion liquid produced by this method is preferably 1.0 or more. The thixotropic ratio of this dispersion is preferably 3.0 or less, more preferably 2.0 or less. In this case, the present dispersion is excellent in coatability and homogeneity, and it is easy to form a more dense molded product (polymer layer or the like).

The total content of the F powder and the inorganic filler in the present dispersion is preferably 40% by mass or more, more preferably 50 to 80% by mass, based on the total mass of the present dispersion. In this method, since the F powder and the inorganic filler are made into composite particles by the shearing treatment, the dispersion stability is improved, and the F powder and the inorganic filler can be contained in the dispersion liquid at a high concentration. Therefore, a molded product such as a coating film can be formed from the dispersion liquid with high uniformity, and the physical characteristics of the F polymer and the physical characteristics of the inorganic filler can be easily expressed in a highly balanced manner.

In this dispersion, the component sedimentation rate is preferably 60% or more, preferably 70% or more, and more preferably 80% or more. Here, the component sedimentation rate is the entire dispersion liquid in the screw pipe before and after standing when the present dispersion liquid (18 mL) is placed in a screw tube (internal volume: 30 mL) and allowed to stand at 25 ° C. for 14 days. It is a value calculated by the following formula from the height of the above and the height of the sedimentation layer (dispersion layer). If the sedimentation layer is not confirmed after standing and there is no change in the state, it is assumed that the height of the entire dispersion liquid does not change, and the component sedimentation rate is 100%.
Erythrocyte sedimentation rate (%) = (height of sedimentation layer) / (height of the entire dispersion) x 100

The dispersion liquid produced by this method is applied to the surface of the sheet base material layer to form a liquid film, and the liquid film is heated to remove the dispersion medium to form a dry film, and the dry film is further heated. Then, by firing the F polymer, a laminate having a polymer layer containing the F polymer and an inorganic filler (hereinafter, also referred to as “F layer”) on the surface of the sheet base material layer can be obtained.

As the sheet base material layer, a metal substrate (copper, nickel, aluminum, titanium, metal foil such as an alloy thereof, etc.), a heat-resistant resin film (polyimide, polyarylate, polysulfone, polyallylsulfone, polyamide, polyetheramide, etc.) A film containing one or more of heat-resistant resins such as polyphenylene sulfide, polyallyl ether ketone, polyamideimide, liquid crystal polyester, and liquid crystal polyester amide, which may be a single-layer film or a multilayer film). Prepreg (precursor of fiber reinforced resin substrate) can be mentioned.

As a method of applying the present dispersion liquid to the surface of the sheet base material, any method may be used as long as a stable liquid film (wet film) composed of the present dispersion liquid is formed on the surface of the sheet base material, and the coating method and droplets are used. Examples thereof include a discharge method and a dipping method, and a coating method is preferable. If the coating method is used, a liquid film can be efficiently formed on the surface of the base material with simple equipment.
The coating methods include spray method, roll coat method, spin coat method, gravure coat method, micro gravure coat method, gravure offset method, knife coat method, kiss coat method, bar coat method, die coat method, fountain Mayer bar method, and slot die coat. The law is mentioned.

When the liquid film is dried, the liquid film is heated at a temperature at which the dispersion medium volatilizes to form a dry film on the surface of the sheet substrate. The heating temperature is preferably + 50 ° C. or lower, the boiling point of the dispersion medium, more preferably 50 ° C. or lower, and further preferably −50 ° C. or lower. The drying temperature is preferably 120 ° C to 200 ° C. Air may be blown in the step of removing the dispersion medium.
At the time of drying, the dispersion medium does not necessarily have to be completely volatilized, and may be volatilized to the extent that the layer shape after holding is stable and the self-supporting film can be maintained.
When firing the F polymer, it is preferable to heat the dry film at a temperature equal to or higher than the melting temperature of the F polymer. The heating temperature is preferably 380 ° C. or lower, more preferably 350 ° C. or lower.
Examples of each heating method include a method using an oven, a method using a ventilation drying furnace, and a method of irradiating heat rays such as infrared rays. The heating may be performed under normal pressure or reduced pressure. The heating atmosphere may be any of an oxidizing gas atmosphere (oxygen gas, etc.), a reducing gas atmosphere (hydrogen gas, etc.), and an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.). ..
The heating time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.
By heating under the above conditions, the F layer can be suitably formed while maintaining high productivity.

The thickness of the F layer is preferably 0.1 to 150 μm. Specifically, when the sheet base material layer is a metal foil, the thickness of the F layer is preferably 1 to 30 μm. When the sheet base material layer is a heat-resistant resin film, the thickness of the F layer is preferably 1 to 150 μm, more preferably 10 to 50 μm.
The peel strength between the F layer and the base material layer is preferably 10 N / cm or more, more preferably 15 N / cm or more. The peel strength is preferably 100 N / cm or less. By using the present dispersion, the present laminate can be easily formed without impairing the physical properties of the F polymer in the F layer.

The porosity of the F layer is preferably 30% or less, more preferably 20% or less. The porosity is preferably 0.1% or more, more preferably 1% or more. From this dispersion, it is easy to form an F layer with a low porosity. In particular, even when the porosity of the dry film is 1% or more, it is easy to form an F layer having a low porosity. The void ratio is determined by image processing to determine the void portion of the F layer from the SEM photograph of the cross section of the molded product observed using a scanning electron microscope (SEM), and the area occupied by the void portion is the area occupied by the F layer. It is the ratio (%) divided by the area. The area occupied by the void portion is obtained by approximating the void portion to a circle.

The present dispersion may be applied only to one surface of the sheet base material layer, or may be applied to both sides of the sheet base material layer. In the former, a laminated body having an F layer on one surface of the sheet base material layer and the sheet base material layer is obtained, and in the latter, the F layer is provided on both the surfaces of the sheet base material layer and the sheet base material layer. A laminate is obtained. Since the latter laminated body is less likely to warp, it is excellent in handleability during its processing.
Specific examples of such a laminate include a metal foil, a metal-clad laminate having an F layer on at least one surface of the metal foil, a polyimide film, and a multilayer film having an F layer on both surfaces of the polyimide film. Can be mentioned.

As the metal foil, a metal foil with a carrier containing two or more layers of metal foil may be used. The metal foil with a carrier includes a carrier copper foil (thickness: 10 to 35 μm) and an ultrathin copper foil (thickness: 2 to 5 μm) laminated on the carrier copper foil via a release layer. Copper foil can be mentioned. By using such a copper foil with a carrier, it is possible to form a fine pattern by an MSAP (modified semi-additive) process. As the release layer, a metal layer containing nickel or chromium or a multilayer metal layer in which the metal layers are laminated is preferable.
Specific examples of the metal leaf with a carrier include the trade name "FUTF-5DAF-2" manufactured by Fukuda Metal Leaf Powder Industry Co., Ltd.
The ten-point average roughness of the surface of the sheet base material layer is preferably 0.01 to 0.05 μm. Since the particles are easy to pack densely, a laminated body having excellent peel strength can be formed even if the surface of the sheet base material layer is smooth.

Here, the outermost surface of the sheet material (the surface opposite to the base material layer of the F layer) may be further surface-treated in order to further improve its low linear expansion property and adhesiveness.
Examples of the surface treatment method include annealing treatment, corona treatment, plasma treatment, ozone treatment, excimer treatment, and silane coupling treatment.
The conditions for the annealing treatment are preferably 120 to 180 ° C., a pressure of 0.005 to 0.015 MPa, and a time of 30 to 120 minutes.
Examples of the gas used for the plasma treatment include oxygen gas, nitrogen gas, noble gas (argon and the like), hydrogen gas, ammonia gas, and vinyl acetate. One type of these gases may be used, or two or more types may be used in combination.

Another substrate may be further laminated on the outermost surface of the laminated body.
Examples of other substrates include a heat-resistant resin film, a prepreg which is a precursor of a fiber-reinforced resin plate, a laminate having a heat-resistant resin film layer, and a laminate having a prepreg layer.
The prepreg is a sheet-like substrate in which a base material (tow, woven fabric, etc.) of reinforcing fibers (glass fibers, carbon fibers, etc.) is impregnated with a thermosetting resin or a thermoplastic resin.
The heat-resistant resin film is a film containing one or more heat-resistant resins, and examples of the heat-resistant resin include the above-mentioned resins.

Examples of the laminating method include a method of heat-pressing the laminated body and another substrate.
When the other substrate is a prepreg, the hot press conditions are preferably such that the temperature is 120 to 400 ° C., the atmospheric pressure is a vacuum of 20 kPa or less, and the press pressure is 0.2 to 10 MPa. Since such a laminate has an F layer having excellent electrical characteristics, it is suitable as a printed circuit board material, and specifically, it can be used as a flexible metal-clad laminate or a rigid metal-clad laminate for manufacturing a printed circuit board, and is particularly flexible. It can be suitably used for manufacturing a flexible printed circuit board as a metal-clad laminate.

A printed circuit board is obtained by etching a metal foil of a laminate (metal foil with an F layer) in which the sheet base material layer is a metal foil to form a transmission circuit. Specifically, a method of etching a metal foil to process it into a predetermined transmission circuit, or a method of processing a metal foil into a predetermined transmission circuit by an electrolytic plating method (semi-additive method (SAP method), MSAP method, etc.). Can be used to manufacture printed circuit boards.
A printed circuit board manufactured from a metal foil with an F layer has a transmission circuit formed from the metal foil and an F layer in this order. Specific examples of the configuration of the printed circuit board include a transmission circuit / F layer / prepreg layer and a transmission circuit / F layer / prepreg layer / F layer / transmission circuit.
In the manufacture of such a printed circuit board, an interlayer insulating film may be formed on the transmission circuit, a solder resist may be laminated on the transmission circuit, or a coverlay film may be laminated on the transmission circuit. These interlayer insulating films, solder resists and coverlay films may be formed with the present dispersion.

The laminate of the F layer and other base materials is useful as antenna parts, printed substrates, aircraft parts, automobile parts, sports equipment, food industry supplies, paints, cosmetics, etc., and specifically, wire coating. Materials (aircraft wires, etc.), electrical insulating tapes, insulating tapes for oil drilling, materials for printed substrates, separation membranes (precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes) Etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), copy rolls, furniture, automobile dashboards, covers for home appliances, sliding members (load bearings, sliding shafts, valves, bearings, gears, cams, etc.) , Belt conveyor, food transport belt, etc.), tools (shovel, razor, cut, saw, etc.), boiler, hopper, pipe, oven, baking mold, chute, die, toilet bowl, container covering material.

As described above, according to this method, the present dispersion having excellent dispersibility and dispersion stability can be obtained. Further, when the dispersion medium is removed from the present dispersion liquid, composite particles containing F powder and an inorganic filler and having excellent dispersibility and dispersion stability can be obtained. Such composite particles can be effectively used as additives and modifiers for various varnishes (resist, ink, paint, etc.) and can impart physical properties of F polymer.

Although the present method, the present dispersion and the present particles (composite particles) have been described above, the present invention is not limited to the configuration of the above-described embodiment.
For example, this method may additionally have any other step in the configuration of the above embodiment, or may be replaced with any step that produces the same action. Further, the dispersion liquid and the particles may be added to any other configuration or may be replaced with any configuration exhibiting the same function in the configuration of the above embodiment.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.
Details of each component are shown below.
[F powder]
F powder 1: A polymer having an acid anhydride group containing 97.9 mol%, 0.1 mol%, and 2.0 mol% of TFE unit, NAH unit, and PPVE unit in this order (melting temperature 300 ° C., acid anhydride). ^{Content of polymer: 1000 particles per 1 × 10 6} carbon atoms in the main chain) (average particle diameter 2 μm, bulk density 0.18 g / m ² )
F powder-2: Particles (average particle diameter 2 μm, bulk) composed of a functional group-free polymer (melting temperature 305 ° C.) containing 97.5 mol% and 2.5 mol% of TFE units and NAH units in this order. Density 0.19 g / m ² )
F powder 3: Particles composed of PTFE having a number average molecular weight of 20,000 (average particle diameter 0.3 μm, bulk density 0.2 g / m ² )
[Inorganic filler]
Filler 1: Silica filler (substantially spherical, average particle diameter 0.4 μm), surface treated with silane coupling agent Filler 2: Silica filler (substantially spherical, average particle diameter 5 μm), surface treated with silane coupling agent Treated filler 3: Borone nitride filler (scaly, average particle size 8 μm)
Filler 4: Boron nitride filler (scaly, average particle size 4 μm)
Filler 5: Silica filler (substantially spherical, average particle diameter 0.03 μm), surface-treated with silane coupling agent Filler 6: Silica filler (substantially spherical, average particle diameter 0.4 μm), silane coupling agent The fillers 3 and 4 are anisotropic fillers.
[Dispersion medium]
NMP: N-methyl-2-pyrrolidone [varnish]
Varnish 1: A varnish in which thermoplastic aromatic polyimide (PI1) is dissolved in NMP [silane coupling agent]
Agent 1: 3-aminopropyltriethoxysilane

1. 1. Production and evaluation of dispersion (1)
[Example 1-1]
(1) NMP and varnish 1 were added to a tank equipped with a stirring blade, and the inside of the tank was sufficiently stirred. Next, F powder 1 was added to the tank and stirred for 10 minutes to prepare a liquid composition (F powder content: 33% by mass) in which F powder 1 was dispersed.
After that, the filler 1 is added, the inside of the tank is stirred at 800 rpm for 15 minutes, and the shearing treatment is performed in a state where an ascending flow is formed. F powder 1 (20 parts by mass), filler 1 (20 parts by mass), varnish 1 A dispersion 1 containing (1 part by mass as PI1) and NMP (59 parts by mass) was obtained.
(2) The viscosity of the obtained dispersion liquid 1 was 400 mPa · s, and the viscosity did not increase even when stirred at 500 rpm for 72 hours with a ball mill, and the component sedimentation rate was evaluated according to the following, and the result was “〇”. ..
<Evaluation criteria for component sedimentation rate>
◯: The erythrocyte sedimentation rate is 60% or more.
Δ: The erythrocyte sedimentation rate is more than 40% and 60% or less.
X: The erythrocyte sedimentation rate is 40% or less.

The state immediately after the preparation of the dispersion liquid 1 and the state after storage in the container at 25 ° C. for 3 hours were visually confirmed, and the dispersion stability was evaluated according to the following criteria.
<Evaluation criteria for dispersion stability>
〇: Immediately after preparation and after storage, there is little foaming and no agglomerates are observed, and the particles are uniformly dispersed. Not dispersed in

(3) A few drops of the obtained dispersion liquid 1 were dropped onto a glass substrate and air-dried at 120 ° C. for 5 minutes. When the obtained solid content was observed with a scanning electron microscope (SEM), it was confirmed that composite particles having F powder 1 as a core and filler 1 as a shell were formed.
The dispersion 1 was concentrated under reduced pressure to distill off 30 parts by mass of NMP, and then filtered. Next, the obtained filtrate was vacuum dried at 25 ° C. to obtain composite particles 1 (D50: 12 μm). The erythrocyte sedimentation rate of the composite particles 1 was "○" as a result of preparing a liquid composition containing the composite particles 1 (40 parts by mass) and NMP (60 parts by mass) and evaluating the same as the above component sedimentation rate. rice field.

[Example 1-2 to Example 1-8]
Dispersions 2 to 8 and composite particles 2 to 8 were obtained in the same manner as in Example 1-1, except that the type and amount of each component were changed as shown in Table 1 below.
In Example 1-7, the stirring speed in the shearing treatment was increased to adjust the viscosity of the obtained dispersion.
In Example 1-8, in addition to NMP and varnish 1, the filler 5 was also stirred in a tank in advance, and F powder 1 was added thereto to produce a dispersion liquid.
Table 1 shows the evaluation results of the obtained dispersion liquid and composite particles.

2. 2. Manufacture and evaluation of laminate (1)
[Example 2-1]
The dispersion liquid 1 was applied to the surface of a long copper foil (thickness 18 μm) using a bar coater to form a wet film. Next, the metal foil on which the wet film was formed was passed through a drying oven at 110 ° C. for 5 minutes and dried by heating to obtain a dry film. Then, the dry membrane was heated at 380 ° C. for 3 minutes in a nitrogen oven. As a result, a laminate 1 having a metal foil and a polymer layer (thickness 20 μm) as a molded product containing a melt-fired product of F powder 1 and filler 1 and PI1 on the surface thereof was produced. The cross section of the laminated body 1 was observed using a scanning electron microscope (SEM), and the porosity was evaluated according to the following criteria.
<Evaluation criteria for porosity>
〇: The porosity is 0% or more and 5% or less.
X: The porosity is more than 5%.

<Electrical characteristics>
A rectangular test piece having a length of 100 mm and a width of 50 mm was cut out from the laminate 1 and etched with an aqueous ferric chloride solution to remove the copper foil to obtain a single polymer layer. After holding the polymer layer alone in an atmosphere of 85 ° C. and 85% relative humidity for 72 hours, the dielectric loss tangent (measurement frequency: 10 GHz) of the polymer layer was measured by the SPDR (split post dielectric resonance) method. It was evaluated according to the criteria of.
[Evaluation criteria for electrical characteristics after water absorption]
〇: The dielectric loss tangent is less than 0.0020.
Δ: The dielectric loss tangent is 0.0020 or more and 0.0040 or less.
X: The dielectric loss tangent is more than 0.0040.

<Linear expansion coefficient>
The copper foil of the laminate 1 was removed by etching with an aqueous solution of ferric chloride to prepare a single polymer layer. A 180 mm square test piece is cut out from the prepared polymer layer, and the linear expansion coefficient of the test piece is measured in the range of 25 ° C. or higher and 260 ° C. or lower according to the measurement method specified in JIS C 6471: 1995, and the following criteria are used. Evaluated according to.
[Evaluation criteria for coefficient of linear expansion]
〇: 50 ppm / ° C or less.
Δ: More than 50 ppm / ° C. and 75 ppm / ° C. or less.
X: Over 75 ppm / ° C.

[Example 2-2 to Example 2-7]
Laminates 2 to 7 were obtained in the same manner as in Example 2-1 except that the dispersions 2 to 7 were used respectively. Table 2 shows the evaluation results for each laminated body.

3. 3. Production and evaluation of dispersion liquid (Part 2)
[Example 3-1]
NMP and varnish 1 were added to a tank provided with a stirring blade and stirred, and then F powder 1 was added and stirred to prepare a liquid composition in which F powder 1 was dispersed.
Then, the filler 1 was added, and the solution in the tank was sheared while stirring the inside of the tank to form an ascending flow. During the shearing treatment, the liquid temperature in the tank was kept at 25 ° C., and the viscosity of the liquid in the tank was kept below 10000 mPa · s. A liquid composition containing the obtained F powder 1 (35 parts by mass), filler 1 (40 parts by mass), varnish 1 (1 part by mass as PI1) and NMP (remaining portion) was prepared, and further NMP was added to the dispersion liquid. 31 (viscosity: 300 mPa · s) was obtained.
A few drops of the dispersion liquid 31 were dropped onto a glass substrate and air-dried at 120 ° C. for 5 minutes to obtain composite particles 31 (D50: 8 μm) having F powder 1 as a core and filler 1 as a shell.

[Example 3-2]
A dispersion liquid 32 was obtained in the same manner as in Example 3-1 except that the agent 1 was further added so as to be 1% by mass with respect to the content of the F powder 1. Further, composite particles 32 (D50: 8 μm) were obtained in the same manner as in Example 3-1 except that the dispersion liquid 31 was changed to the dispersion liquid 32.
[Example 3-3]
Dispersion is performed in the same manner as in Example 3-1 except that the increase in the liquid temperature in the tank due to the shearing treatment of Example 3-1 is not controlled and the liquid temperature in the tank during the shearing treatment temporarily exceeds 50 ° C. Liquid 33 was obtained. Further, the composite particles 33 were obtained in the same manner as in Example 3-1 except that the dispersion liquid 31 was changed to the dispersion liquid 33.
[Example 3-4]
The dispersion liquid 34 was obtained in the same manner as in Example 3-1 except that the stirring in the shearing treatment was strengthened and the viscosity of the liquid in the tank during the shearing treatment exceeded 10,000 mPa · s. Further, the composite particles 34 were obtained in the same manner as in Example 3-1 except that the dispersion liquid 31 was changed to the dispersion liquid 34.
[Example 3-5]
The dispersion liquid 35 was obtained in the same manner as in Example 3-1 except that the filler 1 was changed to the filler 6. Further, the composite particles 35 were obtained in the same manner as in Example 3-1 except that the dispersion liquid 31 was changed to the dispersion liquid 35.

For each of the obtained dispersions 31 to 35, the dispersion stability and the erythrocyte sedimentation rate were evaluated in the same manner as in "Example 1-1". With respect to the composite particles 31 and the composite particles 32, the erythrocyte sedimentation rate was evaluated in the same manner as in "Example 1-1".
The results are shown in Table 3.

4. Manufacture and evaluation of laminate (Part 2)
The laminated body 31 and the laminated body 32 were obtained in the same manner as in Example 2-1 except that the dispersion liquid 1 was changed to the dispersion liquid 31 and the dispersion liquid 32, respectively.
In the laminated body 32, as compared with the laminated body 31, powder falling of the inorganic filler was suppressed at the end portion and the curved surface portion of the polymer layer.

The dispersion liquid produced by the method of the present invention has excellent dispersion stability and can be easily processed into a film, a fiber reinforced film, a prepreg, and a metal laminated plate (metal foil with resin). The obtained processed article can be used as a material for antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry goods, sliding bearings and the like.
Further, the composite particles obtained from the dispersion liquid can be effectively used as additives and modifiers for various varnishes (resist, ink, paint, etc.).

Claims

A liquid composition containing particles of a heat-meltable tetrafluoroethylene polymer, a filler of an inorganic compound, and a polar liquid dispersion medium is sheared to the tetrafluoroethylene polymer, the filler of the inorganic compound, and the liquid. A method for producing a dispersion liquid, which obtains a dispersion liquid containing a dispersion medium.
The tetrafluoroethylene-based polymer contains a unit based on perfluoro (alkyl vinyl ether), and has a tetrafluoroethylene-based polymer having a polar functional group, and 2.0 to 2.0 to all units are based on perfluoro (alkyl vinyl ether). The production method according to claim 1, wherein the production method is at least one selected from the group consisting of a tetrafluoroethylene-based polymer containing 5.0 mol% and having no polar functional group.
The production method according to claim 1 or 2, wherein the liquid dispersion medium is at least one selected from amides, ketones and esters.
The invention according to any one of claims 1 to 3, wherein the total content of the particles of the tetrafluoroethylene polymer and the filler of the inorganic compound is 40% by mass or more with respect to the total mass of the liquid composition. Production method.
The mass ratio of the particles of the tetrafluoroethylene polymer to the filler of the inorganic compound in the liquid composition is 0.01 to 2.0, where the mass of the particles is 1 and the mass of the filler is 0.01 to 2.0. Item 6. The manufacturing method according to any one of Items 1 to 4.
The production method according to any one of claims 1 to 5, wherein the liquid composition contains 20 to 40% by mass of particles of the tetrafluoroethylene polymer and 5 to 40% by mass of a filler of the inorganic compound.
The average particle size (volume-based cumulative 50% diameter) of the filler of the inorganic compound in the liquid composition is 0, based on the average particle size (volume-based cumulative 50% diameter) of the particles of the tetrafluoroethylene polymer. The production method according to any one of claims 1 to 6, which is 0001 to 0.5.
The production method according to any one of claims 1 to 7, wherein the liquid temperature during the shearing treatment is maintained at 70 ° C. or lower.
The production method according to any one of claims 1 to 8, wherein the liquid viscosity during the shearing treatment is maintained at 100,000 mPa · s or less.
The production method according to any one of claims 1 to 9, wherein the filler of the inorganic compound is a silica filler.
The production method according to any one of claims 1 to 10, wherein the filler of the inorganic compound is surface-treated with a silane coupling agent.
The production method according to any one of claims 1 to 11, wherein the liquid composition further contains a silane coupling agent.
The production method according to any one of claims 1 to 12, which obtains a dispersion having a viscosity of 100,000 mPa · s or less.
The production method according to any one of claims 1 to 13, which obtains a dispersion having a component sedimentation rate of 60% or more.
A dispersion liquid is obtained by the production method according to any one of claims 1 to 14, and the liquid dispersion medium is further removed to obtain composite particles containing the tetrafluoroethylene polymer particles and the inorganic compound filler. Obtaining, a method for producing composite particles.