TWI878401B - Dispersion liquid, method for producing dispersion liquid, and formed article - Google Patents

Abstract

The present invention provides a dispersion containing a specific tetrafluoroethylene polymer and a specific anisotropic filler, a method for producing the dispersion, and a molded product having highly physical properties of both. The dispersion of the present invention contains a powder of a tetrafluoroethylene polymer, an anisotropic filler having a Mohs hardness of 4 or less, and a liquid dispersion medium, wherein the tetrafluoroethylene polymer contains a unit based on perfluoro(alkyl vinyl ether) or a unit based on hexafluoropropylene. The average particle size of the powder is smaller than the average particle size of the anisotropic filler. The molded product of the present invention contains a specific tetrafluoroethylene polymer and the anisotropic filler, wherein the specific tetrafluoroethylene polymer contains a unit based on perfluoro(alkyl vinyl ether). The ratio of the anisotropic filler in the molded product is 10% by mass or more.

Description

Dispersion liquid, method for producing dispersion liquid, and formed article

The present invention relates to a dispersion liquid containing a specific anisotropic filler, a production method thereof, and a formed article.

Hot-melt fluorinated polymers such as tetrafluoroethylene polymers (PFA) containing units based on perfluoro(alkyl vinyl ether) and tetrafluoroethylene polymers (FEP) containing units based on hexafluoropropylene have excellent properties such as mold release, electrical insulation, water and oil repellency, chemical resistance, weather resistance, and heat resistance, and are processed into various molded products for use. Patent document 1 describes a wire tube with excellent electrical insulation, which is obtained by melt-kneading PFA powder and a dry mixture of boron nitride filler and extruding it. Prior art documents Patent document

Patent document 1: Japanese Patent Publication No. 2014-224228

[The problem the invention is trying to solve]

However, the melt viscosity of the above-mentioned fluorinated polymers is generally high, and a strong stress is required when melt-kneading the fluorinated polymers and fillers. At this time, the original properties of the filler (especially physical properties such as shape and surface state) are easily damaged, resulting in a decrease in the physical properties of the filler in the molded product. The inventors of the present invention have found that the above trend becomes obvious when the filler is low in hardness and brittle, especially when the filler is low in hardness and anisotropic. In order to obtain a material that is suitable for forming the above-mentioned molded products without relying on melt kneading, the inventors of the present invention have conducted intensive research. As a result, it was found that the dispersion liquid containing a specific fluorinated polymer powder and a specific anisotropic filler has excellent dispersion stability and excellent handling properties such as coating properties. Furthermore, it was found that the properties of the anisotropic filler are not easily damaged in the molded product formed therefrom, and the molded product has both properties to a high degree. The purpose of the present invention is to provide the above-mentioned dispersion and molded product. [Technical means for solving the problem]

The present invention has the following aspects. [1] A dispersion comprising a powder of a tetrafluoroethylene polymer, an anisotropic filler having a Mohs hardness of 4 or less, and a liquid dispersion medium, wherein the tetrafluoroethylene polymer contains units based on perfluoro(alkyl vinyl ether) or units based on hexafluoropropylene, and the average particle size of the powder is smaller than the average particle size of the anisotropic filler. [2] A dispersion as in [1], wherein the content of the tetrafluoroethylene polymer and the content of the anisotropic filler are each 5% by mass or more. [3] A dispersion as in [1] or [2], wherein the anisotropic filler is in the form of a scale or a plate. [4] A dispersion as in any one of [1] to [3], wherein the aspect ratio of the anisotropic filler is 2 or more. [5] A dispersion as described in any one of [1] to [4], wherein the anisotropic filler is an anisotropic filler comprising boron nitride or talc. [6] A dispersion as described in any one of [1] to [5], further comprising a powder of polytetrafluoroethylene or an aromatic polymer. [7] A dispersion as described in any one of [1] to [6], wherein the component dispersion layer ratio is 60% or more. [8] A method for producing a dispersion as described in any one of [1] to [7], the method comprising mixing the powder, the anisotropic filler, an inorganic filler having an average particle size smaller than that of the anisotropic filler, and a liquid dispersion medium. [9] The method as described in [8], wherein the mixing is performed by stirring. [10] A molded article comprising a tetrafluoroethylene polymer containing units based on perfluoro(alkyl vinyl ether) and an anisotropic filler having a Mohs hardness of 4 or less, wherein the tetrafluoroethylene polymer is a polymer having polar functional groups, or a polymer containing 2.0 to 5.0 mol% of the units based on perfluoro(alkyl vinyl ether) and not having polar functional groups relative to the total units, and the ratio of the anisotropic filler in the molded article is 10% by mass or more. [11] A molded article as described in [10], wherein the aspect ratio of the anisotropic filler is 2 or more. [12] A molded article as described in [11], wherein the anisotropic filler is a scaly anisotropic filler containing boron nitride or a plate-like anisotropic filler containing talc. [13] A molded article as described in any one of [10] to [12], wherein the average particle size of the anisotropic filler is greater than 1 μm. [14] A molded article as described in any one of [10] to [13], further comprising polytetrafluoroethylene or an aromatic polymer. [15] A molded article as described in any one of [10] to [14], wherein the molded article is a layered molded article having a thickness of less than 150 μm. [Effect of the Invention]

According to the present invention, a dispersion liquid containing a specific fluorine-containing polymer powder and a specific anisotropic filler with excellent dispersibility and handling properties is obtained. In addition, a molded product is obtained which has high physical properties of both and particularly excellent electrical properties.

The following terms have the following meanings. "Average particle size (D50)" is the volume-based cumulative 50% diameter of the object (powder or filler) obtained by the laser diffraction-scattering method. That is, the particle size distribution of the object is measured by the laser diffraction-scattering method, and the total volume of the particle group of the object is taken as 100% to obtain the cumulative curve. The particle size at the point on the cumulative curve where the cumulative volume becomes 50% is the above-mentioned "average particle size (D50)". "D90" is the volume-based cumulative 90% diameter of the object measured in the same way. "Particle size distribution" is a distribution represented by a curve obtained by plotting the amount of particles (%) in each particle size interval obtained in the same way. "Melting temperature" is the temperature corresponding to the maximum value of the melting peak of the polymer measured by differential scanning calorimetry (DSC). "Glass transition point" is a value obtained by analyzing and measuring the polymer by dynamic viscoelasticity measurement (DMA). "Unit" in a polymer can be an atomic group directly formed from a monomer by polymerization reaction, or an atomic group in which a part of the structure is transformed by treating the polymer obtained by polymerization reaction using a specific method. The unit based on monomer A contained in the polymer is also simply recorded as "monomer A unit".

The dispersion of the present invention (hereinafter, also referred to as "the present dispersion") comprises a powder (hereinafter, also referred to as "F powder") of a tetrafluoroethylene polymer (hereinafter, also referred to as "F polymer"), an anisotropic filler having a Mohs hardness of 4 or less, and a liquid dispersion medium, wherein the tetrafluoroethylene polymer contains a unit (PAVE unit) based on perfluoro(alkyl vinyl ether) (PAVE) or a unit (HFP unit) based on hexafluoropropylene (HFP). In addition, the average particle size of the F powder is smaller than the average particle size of the anisotropic filler. In the present dispersion, the F powder and the anisotropic filler are dispersed. The present dispersion has excellent dispersion stability and handling properties, and is easy to form a molded product having high physical properties of the F polymer and the anisotropic filler. The reason may not be clear, but it is considered as follows.

The anisotropic filler in the present invention can also be called a fragile filler with an amorphous shape and various properties (crystal properties, etc.). In this dispersion, the state of the anisotropic filler is unstable and easily aggregated or precipitated. In addition, the shape or properties of the anisotropic filler are easily destroyed by physical stress (shear stress, etc.). On the other hand, the F polymer is a polymer with plasticity that represents hot melt processability, and its powder (F powder) is difficult to be affected by physical stress, and the dispersibility of the powder is excellent. This dispersion contains the above-mentioned F powder in a state smaller than the average particle size of the anisotropic filler. In other words, the above-mentioned F powder is densely contained, and the affinity between the anisotropic filler and the F powder is in a state that is relatively easy to improve. That is, it is considered that since the F powder is contained in the present dispersion in a more dense and fine particle form, the F powder and the anisotropic filler are in a state where pseudo secondary particles are easily formed. As a result, the dispersion state of the anisotropic filler is stable, and therefore it is considered that the dispersion stability and handling properties of the present dispersion are excellent.

Furthermore, if the liquid dispersion medium is removed from the above-mentioned present dispersion and the F powder is melt-calcined, the deformation of the anisotropic filler is suppressed and a molded product is easily formed. Furthermore, in the process of removing the liquid dispersion medium, the anisotropic filler is easily oriented and a highly filled molded product is obtained. As a result, it is believed that a molded product having highly physical properties of the F polymer and the physical properties of the anisotropic filler is obtained from the present dispersion. For example, if a molded product is formed from the present dispersion containing a scaly or plate-like anisotropic filler, the anisotropic filler is oriented parallel to the surface (surface direction) of the molded product, and the physical properties of the anisotropic filler in the molded product are easily highly expressed. Therefore, if the present dispersion is used, the physical properties of the F polymer and the physical properties of the anisotropic filler are easily highly expressed even in a thin layer-like molded product.

Furthermore, if the anisotropic filler is in the form of scales or plates, the anisotropic filler is easy to form a sheet frame structure, thereby improving the liquid properties (viscosity, dispersion stability, etc.) of the present dispersion. Moreover, the anisotropic filler is easy to be highly dispersed in the molded object formed therefrom. As a result, the molded object is easy to have excellent electrical characteristics. In addition, when the molded object is subjected to stress, the stress is easy to be dispersed by the anisotropic filler, and the mechanical strength (bendability, etc.) is easy to improve. Furthermore, a passage of the anisotropic filler is formed in the molded object, so the thermal conductivity of the molded object is easy to improve.

The F powder in the present dispersion preferably contains an F polymer. The content of the F polymer in the powder is preferably 80% by mass or more, and more preferably 100% by mass. As other components that the F powder may contain, resins or inorganic substances different from the F polymer may be cited. As different resins, aromatic polyesters, polyamide imides, thermoplastic polyimides, polyphenylene ethers, and polyphenylene ethers may be cited. As inorganic substances, silicon oxide (silicon dioxide), metal oxides (curia, bainite, aluminum oxide, alkali aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.), boron nitride, and magnesium metasilicate (talc) may be cited.

The F powder containing a resin or inorganic substance different from the F polymer is preferably a core-shell structure: the F polymer is the core and the resin or inorganic substance is the shell; or the resin or inorganic substance is the core and the F polymer is the shell. The F powder is obtained, for example, by combining the powder of the F polymer with the powder of the resin or inorganic substance (collision, agglomeration, etc.).

The D50 of the F powder is preferably 10 μm or less, more preferably 6 μm or less, and further preferably 4 μm or less. The D50 of the F powder is preferably 0.01 μm or more, more preferably 0.1 μm or more, and further preferably 1 μm or more. Furthermore, the D90 of the F powder is preferably 20 μm or less, and further preferably 10 μm or less. If the D50 and D90 of the F powder are within the above ranges, the affinity with the anisotropic filler is further improved, so that the dispersion stability of the present dispersion and the physical properties of the molded product are easily improved.

The content of the F powder in the present dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 25% by mass or more. The content of the F powder is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. If the content of the F powder is within the above range, the affinity between the F powder and the anisotropic filler is improved due to the dense inclusion of the F powder, so that the dispersion stability of the present dispersion is easily improved. In addition, the physical properties of the F polymer in the molded product are easily and significantly expressed.

The F polymer in the present dispersion contains units based on tetrafluoroethylene (TFE) (TFE units). The F polymer may contain both _PAVE units and _HFP units, or only one of them. PAVE is preferably _CF2 = _CFOCF3 , _CF2 = _CFOCF2CF3 or _CF2 = _CFOCF2CF2CF3 (PPVE), more preferably PPVE. The melting temperature of the F polymer is preferably 280-325°C, more preferably 285-320°C. The glass transition point of the F polymer is preferably 75-125°C, _more preferably 80-100°C.

The F polymer may have a polar functional group (oxygen-containing polar group). The polar functional group may exist in a unit in the F polymer or may exist in a terminal group of the main chain of the polymer. As the latter aspect, there may be exemplified: an F polymer having a polar functional group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc.; an F polymer having a polar functional group obtained by subjecting the F polymer to plasma treatment or ionizing radiation treatment. The polar functional group is preferably a hydroxyl-containing group or a carbonyl-containing group, and is more preferably a carbonyl-containing group from the viewpoint of the dispersion stability of the present dispersion. The hydroxyl-containing group is preferably a group containing an alcoholic hydroxyl group, and is more preferably -CF ₂ CH ₂ OH or -C(CF ₃ ) ₂ OH. The carbonyl-containing group is a group containing a carbonyl group (＞C(O)), preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH ₂ ), an anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.) or a carbonate group (-OC(O)O-). Regarding the number of carbonyl-containing groups in the F polymer, the number is preferably 10 to 5000 per 1×10 ⁶ carbon atoms in the main chain, more preferably 100 to 3000, and further preferably 800 to 1500. Furthermore, the number of carbonyl-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.

As the F polymer, a tetrafluoroethylene polymer containing PAVE units and containing 1.5 to 5.0 mol% of PAVE units relative to the total units is preferred, and a polymer (1) or a polymer (2) is more preferred, wherein the polymer (1) contains PAVE units and units based on monomers having polar functional groups and has polar functional groups; and the polymer (2) contains PAVE units and contains 2.0 to 5.0 mol% of PAVE units relative to the total units and does not have polar functional groups. These F polymers not only have excellent dispersion stability of their powders, but are also easily distributed more densely and uniformly in a molded product (polymer layer, etc.) formed by the present dispersion. Furthermore, microspherulites are easily formed in the molded product, and adhesion with other components is easily improved. As a result, it is easier to obtain a molded product that highly possesses the physical properties of each of the three components mentioned above.

The polymer (1) preferably contains 90 to 98 mol% of TFE units, 1.5 to 9.97 mol% of PAVE units, and 0.01 to 3 mol% of units based on monomers having polar functional groups, relative to the total units. In addition, the monomer having a polar functional group is preferably itaconic anhydride, cisaconic anhydride, or 5-northene-2,3-dicarboxylic anhydride (also known as bicycloheptene dicarboxylic anhydride; hereinafter also referred to as "NAH"). As a specific example of the polymer (1), the polymer described in International Publication No. 2018/16644 can be cited.

The polymer (2) is preferably composed only of TFE units and PAVE units, and contains 95.0-98.0 mol% of TFE units and 2.0-5.0 mol% of PAVE units relative to the total units. The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more relative to the total units. Furthermore, the polymer (2) does not have polar functional groups, which means that the number of polar functional groups possessed by the polymer is less than 500 per 1×10 ⁶ carbon atoms constituting the main chain of the polymer. The number of the above-mentioned polar functional groups is preferably less than 100, and more preferably less than 50. The lower limit of the number of the above-mentioned polar functional groups is usually 0. The polymer (2) can be produced by using a polymerization initiator or a chain transfer agent that does not generate a polar functional group as an end group of the polymer chain, or by fluorinating an F polymer having a polar functional group (an F polymer having a polar functional group derived from a polymerization initiator at the end group of the main chain of the polymer). As a method of fluorination treatment, a method using fluorine gas can be cited (see Japanese Patent Publication No. 2019-194314, etc.).

The Mohs hardness of the anisotropic filler in the present invention is 4 or less, preferably 3 or less. The Mohs hardness of the anisotropic filler is preferably 1 or more, more preferably 2 or more. Even if the Mohs hardness is a brittle anisotropic filler within the above range, the dispersion stability of the present dispersion is excellent due to the affinity between the anisotropic filler and the F powder, thereby easily improving the physical properties of the filler in the molded product. One type of anisotropic filler may be used, or two or more types with different average particle sizes or types may be used.

The shape of the anisotropic filler in the present invention can be any of granular, needle-shaped (fiber-shaped), and plate-shaped. As specific shapes of the anisotropic filler, there can be cited: spherical, scaly, layered, leaf-shaped, almond-shaped, columnar, cockscomb-shaped, isometric, leaf-shaped, mica-shaped, block-shaped, flat-plate-shaped, wedge-shaped, rose-shaped, mesh-shaped, and angular columnar. The shape of the anisotropic filler is preferably scaly or plate-shaped. If a scaly or plate-shaped anisotropic filler is used, it is easy to form a sheet-frame structure, and it is easy to improve the liquid properties of the dispersion (viscosity, dispersion stability, etc.). Not only that, it is also easy to improve the orientation of the filler in the molded product, and it is easy to improve its functions (mechanical strength, thermal conductivity, electrical properties, etc.).

As anisotropic fillers, carbon fillers, nitride fillers, mica fillers, clay fillers, and talc fillers can be cited. Preferably, fillers containing boron nitride or talc are used, and more preferably, fillers containing boron nitride are used. The crystal form of boron nitride can be any one of hexagonal crystals, rhombohedral crystals, cubic crystals, and fibrous zinc ore. The dispersion liquid containing the above-mentioned anisotropic fillers has excellent dispersion stability and handling properties. In addition, the electrical interference of the filler to the F polymer in the molded product is easily increased, and as a result, the electrical properties of the molded product (especially the dielectric dissipation factor) are easily improved. Furthermore, the thermal conductivity of the molded product is easily improved.

The content of boron nitride in the filler containing boron nitride is preferably 95 mass % or more, more preferably 99 mass % or more, and further preferably 99.5 mass % or more. The upper limit of the content is 100 mass %. In this case, the molded product is likely to have low linear expansion and excellent electrical properties. When anisotropic fillers are added to water, the pH value of the water can be any of acidic, neutral, and alkaline, preferably alkaline. The specific surface area of the anisotropic filler is preferably 1 to 20 m ² /g, more preferably 3 to 8 m ² /g. In this case, the anisotropic filler in the present dispersion is easily wetted, and the affinity with the F powder is easily enhanced. Furthermore, in the molded product, the anisotropic filler and the F polymer are dispersed (distributed) more uniformly, and the physical properties of both are easily exhibited in a well-balanced manner.

The surface of the anisotropic filler can be surface treated. Examples of surface treatment agents include: polyols (trihydroxymethylethane, pentaerythritol, propylene glycol, etc.), saturated fatty acids (stearic acid, lauric acid, etc.), saturated fatty acid esters, alkanolamines, amines (trimethylamine, triethylamine, etc.), wax, silane coupling agents, polysiloxanes, polysiloxanes, inorganic substances (oxides, hydroxides, hydrated oxides or phosphates of aluminum, silicon, zirconium, tin, titanium, antimony, etc.). As a surface treatment agent, a silane coupling agent is preferred. In the above case, the anisotropic filler is more compatible with the powder of the F polymer, and the dispersion stability of the dispersion is easily improved. The silane coupling agent preferably has an amine group, a thiol group, a vinyl group, an acryloxy group or a methacryloxy group.

The anisotropic filler may be an anisotropic filler having a hydrophobic portion and a hydrophilic portion. As the above-mentioned anisotropic filler, an anisotropic filler having a hydrophobic layer on the surface and a hydrophilic layer inside can be cited. As a specific example, a plate-shaped multi-layer filler having a hydrophobic layer, a hydrophilic layer (water-containing layer), and a hydrophobic layer in sequence can be cited. The water content of the hydrophilic layer is preferably 0.3% by mass or more. In this case, not only is the dispersion state of the anisotropic filler in the dispersion liquid easy to stabilize, but also the orientation of the anisotropic filler when forming a molded product from the dispersion liquid is further improved, and it is easy to obtain a molded product that highly possesses the physical properties of the F polymer and the physical properties of the anisotropic filler.

The D50 of the anisotropic filler is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more. The D50 of the anisotropic filler is preferably 25 μm or less, and more preferably 20 μm or less. The D90 of the anisotropic filler is preferably 10 μm or more, and more preferably 15 μm or more. The D90 of the anisotropic filler is preferably 30 μm or less, and more preferably 20 μm or less. If the D50 and D90 of the anisotropic filler are within the above range, the affinity with the F powder is further improved, and it is easy to further improve the dispersion stability of the present dispersion and the physical properties of the molded product. Specific examples of the above-mentioned anisotropic filler include scaly boron nitride fillers and plate-like talc fillers.

The aspect ratio of the anisotropic filler is preferably 2 or more, more preferably 3 or more, further preferably 5 or more, and particularly preferably 10 or more. The aspect ratio of the anisotropic filler is preferably 10,000 or less. In this case, it is easy to further improve the orientation of the filler in the molded product, and it is easy to improve its function. Specifically, not only is the dispersion state of the anisotropic filler in the dispersion liquid easy to stabilize, but the orientation of the anisotropic filler when the molded product is formed from the dispersion liquid is also further improved, and it is easy to obtain a molded product that has both the physical properties of the F polymer and the physical properties of the anisotropic filler.

Furthermore, the aspect ratio of the anisotropic filler is a value obtained by dividing the average particle size (D50) of the anisotropic filler by the average minor diameter (average value of the length in the short side direction) of the anisotropic filler. As a specific form of the above-mentioned anisotropic filler, a filler having an average minor diameter of 1 μm or less, or an average major diameter (average value of the length in the long side direction) of 1 μm or more can be cited. As a specific example of the above-mentioned anisotropic filler, a flat talc filler can be cited. The anisotropic filler can be a single-layer structure or a multi-layer structure. As an example of the above-mentioned anisotropic filler, a talc filler having a three-layer structure can be cited.

Suitable specific examples of the anisotropic filler include boron nitride fillers ("UHP" series manufactured by Showa Denko, "HGP" series, "GP" series manufactured by Denka, etc.), and talc fillers ("SG" series manufactured by Nippon Talc Co., Ltd., etc.).

In the present dispersion, the D50 of the F powder is smaller than the D50 of the anisotropic filler. That is, in the present dispersion, by densely containing the fine-particle F powder, the affinity between the F powder and the anisotropic filler is improved, thereby improving the dispersion stability of the present dispersion. Furthermore, in the molded product, the anisotropic filler is more uniformly dispersed and its physical properties are easily and obviously expressed. Specifically, it is preferred that the D50 of the F powder is greater than 0.1 μm and less than 5 μm, and the D50 of the anisotropic filler is greater than 1 μm and less than 25 μm.

As a suitable embodiment of the filler contained in the present dispersion, the following embodiment can be cited: an anisotropic filler (hereinafter, also referred to as "anisotropic filler 1") is included, and an inorganic filler (hereinafter, also referred to as "different filler") having an average particle size smaller than that of the anisotropic filler 1 is further included. In this case, the improvement of the dispersion stability of the present dispersion caused by the interaction between the fillers and the ability of the different fillers to form a dense molded product are balanced, and the physical properties (water resistance, low linear expansion, electrical characteristics, etc.) of the obtained molded product are easily further improved. Furthermore, the different filler only needs to be an inorganic filler having an average particle size smaller than that of the anisotropic filler 1, and its material can be the same as or different from that of the anisotropic filler 1.

In the suitable embodiment, it is preferred that the average particle size of the anisotropic filler 1 is greater than 6 μm and less than 15 μm, and the average particle size of the different fillers is greater than 1 μm and less than 6 μm. In this case, it is preferred that the anisotropic filler 1 is a filler containing boron nitride, and the different fillers are fillers containing boron nitride or magnesium metasilicate fillers (talc fillers). In addition, the aspect ratio of the anisotropic filler 1 is greater than 10, and the aspect ratio of the different fillers is preferably less than 40, and more preferably less than 10. In this case, in the obtained molded product, the random orientation of the anisotropic filler 1 is promoted due to the different fillers, so that the physical properties of the filler and the physical properties of the molded product (adhesion, rigidity, etc.) are easily balanced.

In the suitable embodiment, it is also preferred that the average particle size of the anisotropic filler 1 is greater than 1 μm and less than 15 μm, and the average particle size of the different fillers is greater than 0.01 μm and less than 1 μm. At this time, it is preferred that the anisotropic filler 1 is a filler containing boron nitride, and the different fillers are fillers containing silicon oxide. The filler containing silicon oxide is preferably a silicon dioxide filler or a magnesium metasilicate filler (talc filler). In addition, the surface of the filler containing silicon oxide is preferably surface treated with a silane coupling agent.

The filler containing silicon oxide is preferably substantially spherical. In this case, it is easy to form a densely molded product. Furthermore, substantially spherical means that when observed by a scanning electron microscope (SEM), the ratio of spherical particles with a short diameter to a long diameter ratio of 0.7 or more accounts for more than 95%. Specific examples of the filler containing silica include: approximately true spherical silica fillers (such as the "Admafine" series manufactured by Admatechs), spherical fused silica (such as the "SFP" series manufactured by Denka), hollow silica fillers (such as the "E-SPHERES" series manufactured by Taiheiyo Cement, the "SiliNax" series manufactured by Nippon Steel Mining Co., Ltd., and the "Ecco sphere" series manufactured by Emerson & Cuming), and block talc fillers (such as the "BST" series manufactured by Nippon Talc).

In this preferred embodiment, the random orientation of the anisotropic filler 1 in the molded article is promoted by different fillers, and it is easy to balance the filler properties in the molded article with the molded article properties (adhesion, surface smoothness, rigidity, etc.). That is, in the molded article, the orientation of the anisotropic filler 1 is partially disordered, so that the molded article is easy to have high electrical characteristics and low linear expansion due to high filler orientation, and rigidity, adhesion and surface smoothness due to disordered filler orientation.

Furthermore, the filler in the preferred embodiment may also be included in a state of having a multimodal particle size distribution. In this case, from the viewpoint of facilitating the formation of a dense molded product, it is preferred that the peak derived from the present filler 1 is the highest among the peaks of the particle size distribution. Specifically, the filler is preferably included in a state of having a bimodal particle size distribution, and the bimodal particle size distribution means having peaks in the region below 6 μm and in the region above 6 μm.

In addition, the filler in the preferred embodiment may be included in a state where at least a portion of the filler is attached to the surface of the F powder, or may be included in a state where at least a portion of the F powder is attached to the surface of the filler. In this case, the present dispersion may be said to be a composite comprising the F powder and the anisotropic filler 1, and its dispersion stability is further improved, and it is easy to further improve various properties (water resistance, low linear expansion, electrical characteristics, etc.) of the molded product formed therefrom.

Furthermore, in the preferred embodiment, the mass ratio of the content of the different fillers to the content of the anisotropic filler 1 is preferably 0.1 or more, more preferably 0.2 or more. Moreover, the mass ratio is preferably 2 or less, more preferably 1 or less. In this case, the dispersion stability of the dispersion and the physical properties of the molded product are easily balanced.

The content of the anisotropic filler in the present dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 25% by mass or more. The content of the F powder is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. The content of the F polymer and the content of the anisotropic filler in the present dispersion are preferably 5% by mass or more, respectively. The sum of the contents of the two is preferably 60% by mass or less. Even if the F polymer and the anisotropic filler are contained in the above-mentioned higher ratio (content), as described in the above-mentioned mechanism of action, the dispersion stability of the present dispersion is excellent, and it is easy to form a molded product with high physical properties of both.

From the viewpoint of improving dispersion stability and handling properties, the present dispersion preferably further contains a surfactant. The surfactant is preferably nonionic. The hydrophilic part of the surfactant preferably has an oxyalkylene group or an alcoholic hydroxyl group. The oxyalkylene group may contain one type or two or more types. In the latter case, different types of oxyalkylene groups may be arranged randomly or in blocks. The oxyalkylene group is preferably an oxyethylene group.

The hydrophobic part of the surfactant is preferably an acetylene group, a polysiloxane group, a perfluoroalkyl group or a perfluoroalkenyl group. In other words, the surfactant is preferably an acetylene surfactant, a polysiloxane surfactant or a fluorine surfactant, and more preferably a polysiloxane surfactant. As a fluorine surfactant, it is further preferred to have a hydroxyl group (especially an alcoholic hydroxyl group) or an oxyalkylene group, and a perfluoroalkyl group or a perfluoroalkenyl group. Specific examples of surfactants include: "FTERGENT" series (manufactured by NEOS), "Surflon" series (manufactured by AGC Seimei Chemical Co., Ltd.), "MEGAFAC" series (manufactured by DIC), "Unidyne" series (manufactured by Daikin Industries), "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", "BYK-3456" (manufactured by BYK-Chemie Japan Co., Ltd.), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.). The content of the surfactant in the dispersion is preferably 1 to 15% by mass. In this case, the affinity between the components is enhanced, and the dispersion stability of the present dispersion liquid is likely to be further improved.

The liquid dispersion medium in the present invention is a liquid compound that functions as a dispersion medium for F powder and anisotropic filler and is inert at 25°C. The liquid dispersion medium may be water or a non-aqueous dispersion medium. The liquid dispersion medium may be one type or two or more types. In this case, different types of liquid compounds are preferably miscible. The boiling point of the liquid dispersion medium is preferably 125 to 250°C. In this case, when a molded product is formed from the present dispersion, the anisotropic filler is easily oriented, and the physical properties of the molded product are easily improved. As the liquid dispersion medium, from the viewpoint of the dispersion stability of the present dispersion, it is preferably a liquid compound selected from the group consisting of amides, ketones and esters, and more preferably N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone or cyclopentanone. The content of the liquid dispersion medium in the present dispersion is preferably 50% by mass or more, and more preferably 60% by mass or more. The content of the liquid dispersion medium is preferably 90% by mass or less, and more preferably 80% by mass or less.

The viscosity of the present dispersion is preferably 50 mPa・s or more, more preferably 100 mPa・s or more. The viscosity of the present dispersion is preferably 10000 mPa・s or less, more preferably 1000 mPa・s or less, and further preferably 800 mPa・s or less. The thixotropic ratio of the present dispersion is preferably 1.0 or more. The thixotropic ratio of the present dispersion is preferably 3.0 or less, and further preferably 2.0 or less. The component dispersion layer ratio of the present dispersion is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more. Here, the component dispersion layer ratio is the value calculated by the following formula based on the total height of the present dispersion in the spiral tube before and after standing and the height of the component dispersion layer after adding the present dispersion (18 mL) to a spiral tube (content volume: 30 mL) and standing at 25°C for 14 days. Component dispersion layer ratio (%) = (height of component dispersion layer) / (total height of the present dispersion) × 100 Furthermore, if the component dispersion layer is not confirmed after standing and the state does not change, it is considered that the total height of the present dispersion has not changed, and the component dispersion layer ratio is considered to be 100%. The present dispersion is easy to adjust to the above range of viscosity, thixotropy or component dispersion layer ratio by the above mechanism of action, and has excellent handling properties.

The present dispersion may further include other resins (polymers) different from the F polymer. The other resins may be thermosetting resins or thermoplastic resins. Examples of other resins include epoxy resins, butylene imide resins, urethane resins, elastomers, polyimides, polyamides, polyamide imides, polyphenylene ethers, polyphenylene stretch ethers, liquid crystal polyesters, and fluorine-containing polymers other than the F polymer. As a suitable form of other resins, varnishes of aromatic polymers may be cited. The aromatic polymer is preferably an aromatic polyimide or an aromatic polyamide, and more preferably a thermoplastic aromatic polyimide. In this case, the physical properties of the F polymer and the anisotropic filler are likely to be clearly manifested in the molded product. In addition, when the molded product is formed from the present dispersion, the falling of the F powder is also suppressed, and the adhesion of the molded product is likely to be further improved.

The content of the aromatic polymer in the present dispersion is preferably 1 to 30% by mass, more preferably 5 to 25% by mass. The mass ratio of the content of the aromatic polymer to the content of the F polymer is preferably less than 1.0, more preferably 0.1 to 0.7. As a suitable form of other resins, polytetrafluoroethylene (PTFE) powder can be cited. In this case, the physical properties based on PTFE (electrical properties such as low dielectric dissipation factor) are easily and obviously manifested in the molded product. In addition, PTFE will become a nucleating agent, making it easy for the F polymer in the molded product to form microcrystals, improving the adhesion to the surface of the molded product, and its adhesion is easy to improve. In addition, it is easy to improve the orientation of the filler in the molded product, and it is easy to enhance its function.

The PTFE is preferably a PTFE (low molecular weight PTFE) having a number average molecular weight (Mn) of 200,000 or less calculated based on the following formula (1). Mn = 2.1 × 10 ¹⁰ × ΔHc ^-5.16 (1) In formula (1), ΔHc represents the crystallization heat (cal/g) of PTFE measured by differential scanning calorimetry. The Mn of the low molecular weight PTFE is preferably 100,000 or less, and more preferably 50,000 or less. The Mn of the low molecular weight PTFE is preferably 10,000 or more.

The content of PTFE in the present dispersion is preferably 1 to 30% by mass, more preferably 5 to 20% by mass. The mass ratio of the content of PTFE to the content of F polymer is preferably 1.0 or less, more preferably 0.1 to 0.4. The present dispersion containing other resins can be prepared by mixing the present dispersion with powders of other resins, or by mixing the present dispersion with varnish containing other resins.

In addition to the above ingredients, the dispersion may also contain additives such as thixotropic agents, defoaming agents, silane coupling agents, dehydrating agents, plasticizers, weathering agents, antioxidants, thermal stabilizers, lubricants, antistatic agents, whitening agents, coloring agents, conductive agents, mold release agents, surface treatment agents, viscosity regulators, flame retardants, isotropic fillers, etc.

The present dispersion can be produced by mixing F powder, anisotropic filler and liquid dispersion medium. It is preferably produced by separately preparing a liquid composition containing F powder and a liquid composition containing anisotropic filler and mixing the two. As a specific production method of the present dispersion, the following production method can be cited: F powder, anisotropic filler 1, different fillers, and liquid dispersion medium are mixed. During the mixing, F powder and liquid dispersion medium can be mixed in advance to form a liquid composition, and anisotropic filler 1 and the above-mentioned different fillers can also be mixed in advance.

Examples of mixers used for mixing include agitators using stirring blades, Henschel mixers, ribbon mixers, oscillating mixers, vibrating mixers, and rotary mixers. Specifically, examples include homogenizers, homogenizers, and ball mills. The mixing method may be either batch or continuous. The mixer used for batch mixing is preferably a Henschel mixer, a pressure kneader, a Banbury mixer, or a planetary mixer.

The mixing is preferably performed by stirring, and more preferably by rotating stirring using a stirring blade. The stirring speed is preferably 800 rpm or more, and more preferably 2000 rpm or more. The stirring speed is preferably 10000 rpm or less, and more preferably 8000 rpm or less. In this case, shearing is applied to the F powder and the anisotropic filler, and the agglomerates are easily crushed, and the present dispersion liquid with excellent dispersibility is easily obtained. Furthermore, if the anisotropic filler is scaly or plate-shaped, the layered agglomerates (secondary particles) of the anisotropic filler formed are usually crushed efficiently while forming a sheet frame structure, so that the present dispersion liquid with excellent dispersibility is easily formed.

The molded article of the present invention (hereinafter, also referred to as "the present molded article") comprises a tetrafluoroethylene polymer containing PAVE units (hereinafter, also referred to as "PFA polymer") and an anisotropic filler having a Mohs hardness of 4 or less. Moreover, the PFA polymer is a polymer having a polar functional group, or a polymer containing 2.0 to 5.0 mol% of PAVE units relative to the total units and having no polar functional groups, and the ratio (content) of the anisotropic filler in the present molded article is 10% by mass or more. As the shape of the present molded article, there can be cited: layered, plate-like, block-like, preferably layered. The thickness of the layered molded article is preferably 150 μm or less. The above-mentioned layered molded article can be used to manufacture impregnated articles such as films and prepregs or laminated boards.

The definition and scope of the anisotropic filler in the present molded article, including suitable aspects, are the same as the definition and scope of the anisotropic filler in the present dispersion. The type and scope of the polar functional group possessed by the PFA-based polymer in the present molded article, including suitable aspects, are the same as the type and scope of the polar functional group in the F polymer. Furthermore, the PFA-based polymer is preferably polymer (1) or polymer (2).

The content of the anisotropic filler in the present molded product is preferably 15% by mass or more, more preferably 25% by mass or more. The content of the anisotropic filler is preferably 50% by mass or less, and further preferably 40% by mass or less. The content of the PFA-based polymer in the present molded product is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass or more. The content of the PFA-based polymer is preferably 95% by mass or less, more preferably 80% by mass or less, and further preferably 70% by mass or less. If the content of the PFA-based polymer is within the above range, the physical properties of the PFA-based polymer are easily and significantly manifested in the present molded product. In addition, the powdering of the anisotropic filler from the present molded product is suppressed.

The present molded product preferably further contains an aromatic polymer (especially aromatic polyimide) or PTFE. The definitions and ranges of the aromatic polymer and PTFE in the present molded product, as well as the mass ratio of their respective contents relative to the content of the F polymer, are the same as those in the present dispersion. The present molded product is preferably formed from the present dispersion. Specifically, if the present dispersion is applied to the surface of a substrate and its liquid dispersion medium is removed, a layer (hereinafter also referred to as "this layer") containing a PFA-based polymer and anisotropic filler as the present molded product can be easily formed on the surface of the substrate. More specifically, the present dispersion is applied to the surface of a substrate and the substrate is heated to remove the liquid dispersion medium, and then heated to melt-bake the PFA-based polymer, so that a laminate having a substrate and the present layer formed on the surface of the substrate can be obtained. The heating temperature of the former is preferably 120°C to 200°C. On the other hand, the heating temperature of the latter is preferably 250°C to 400°C, more preferably 300°C to 380°C.

Examples of the substrate include metal substrates (metal foils of copper, nickel, aluminum, titanium, alloys thereof, etc.), resin films (films of polyimide, polyarylate, polysulfone, polyaryletherketone, polyamide, polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, liquid crystal polyester, liquid crystal polyesteramide, etc.), and prepregs (preprepared products of fiber-reinforced resin substrates). The dispersion is preferably applied by coating. Examples of coating methods include spraying, roller coating, rotary coating, gravure coating, micro-gravure coating, gravure offset coating, scraper coating, contact coating, rod coating, die nozzle coating, injection merrer bar coating, and slot die nozzle coating. Examples of heating methods include methods using an oven, methods using a ventilation drying furnace, and methods using infrared or other heat rays.

The thickness of this layer is preferably 0.1 to 150 μm. Specifically, if the substrate is a metal foil, the thickness of this layer is preferably 1 to 30 μm. If the substrate is a resin film, the thickness of this layer is preferably 1 to 150 μm, and more preferably 10 to 50 μm. This dispersion can be applied to only one surface of the substrate or to both surfaces of the substrate. The former can obtain a laminate having a substrate and the present layer on one surface of the substrate, and the latter can obtain a laminate having a substrate and the present layer on both surfaces of the substrate. The latter laminate is more difficult to warp, so it has excellent processing properties during processing. As specific examples of the above-mentioned laminates, there can be cited: a metal-coated laminate having a metal foil and a main layer present on at least one surface of the metal foil; a multilayer film having a polyimide film and a main layer present on both sides of the polyimide film. Such laminates have excellent physical properties such as electrical properties, and are therefore suitable as printed circuit board materials. Specifically, the above-mentioned laminates can be used to manufacture flexible printed circuit boards or rigid printed circuit boards. Implementation Examples

The present invention is described in detail below by way of embodiments, but the present invention is not limited thereto. 1. Preparation of each component [Powder] Powder 1: Powder (D50: 2.1 μm) containing PFA-based polymer 1 (melting temperature: 300°C), wherein the PFA-based polymer 1 contains 97.9 mol% of TFE units, 0.1 mol% of NAH units, and 2.0 mol% of PPVE units in sequence, and each 1×10 ⁶ carbon atoms in the main chain has 1000 carbonyl groups. Powder 2: Powder (D50: 1.8 μm) containing PFA-based polymer 2 (melting temperature 305°C), wherein the PFA-based polymer 2 contains 97.5 mol% of TFE units and 2.5 mol% of PPVE units in sequence, and each 1×10 ⁶ carbon atoms in the main chain has 40 carbonyl groups. Powder 3: Powder (D50: 5.3 μm) containing PFA-based polymer 2 Powder 4: Powder containing PTFE with a number average molecular weight of 20,000 (D50: 3.2 μm)

[Anisotropic filler] Filler 1: scaly filler containing boron nitride (D50: 7.0 μm) Filler 2: scaly filler containing boron nitride (D50: 3.7 μm) Filler 3: scaly filler containing boron nitride (D50: 7.3 μm) Filler 4: plate-like talc filler having a three-layer structure of a hydrophobic layer, a hydrophilic layer, and a hydrophobic layer in sequence (D50: 4.5 μm, average major diameter: 5.1 μm, average minor diameter: 0.2 μm, aspect ratio: 25, "SG-95" manufactured by Japan Talc Co., Ltd.) In addition, the Mohs hardness of fillers 1 to 3 is 2, and the Mohs hardness of filler 4 is 1. Fillers 1, 2, and 4 are surface treated with a silane coupling agent. [Liquid dispersion medium] NMP: N-methyl-2-pyrrolidone

[Surfactant] Surfactant 1: Non-ionic polymer, which is a copolymer of CH ₂ =C(CH ₃ )C(O)OCH ₂ CH ₂ (CF ₂ ) ₆ F and CH ₂ =C(CH ₃ )C(O)(OCH ₂ CH ₂ ) ₂₃ OH, and the fluorine content is 35% by mass. [Aromatic polymer varnish] Varnish 1: Varnish prepared by dissolving thermoplastic aromatic polyimide (PI1) in NMP (N-Methylpyrrolidone) (solid content concentration: 18% by mass)

2. Example of preparing dispersion liquid (Example 1) First, powder 1, varnish 1, surfactant 1, NMP and zirconia balls were added to a crucible. Then, the crucible was rotated at 150 rpm for 1 hour to prepare a composition. Filler 1, surfactant 1 and NMP were added to another crucible and zirconia balls were added. Then, the crucible was rotated at 150 rpm for 1 hour to prepare a composition. The combination of the two was added to another crucible and zirconia balls were added. Then, the crucible was rotated at 150 rpm for 1 hour to obtain a dispersion liquid 1 (viscosity: 400 mPa・s) containing powder 1 (11 parts by mass), filler 1 (11 parts by mass), PI1 (7 parts by mass), surfactant 1 (4 parts by mass) and NMP (67 parts by mass). (Examples 2 to 9) Dispersions 2 to 9 were obtained in the same manner as in Example 1 except that the types and amounts of powders, fillers, varnishes, surfactants, and liquid dispersion media were changed as shown in Table 1 below. (Example 10) Dispersion 10 was obtained in the same manner as in Example 1 except that 3 parts by mass of filler 1 and 8 parts by mass of filler 2 were used instead of 11 parts by mass of filler 1.

[Table 1] Dispersion No. powder filler Aromatic polymers Surfactant Liquid dispersion medium 1 Powder 1(11) Packing 1(11) PI1(7) Surfactant 1(4) NMP(67) 2 Powder 1 (7) Powder 4 (4) Packing 1(11) PI1(7) Surfactant 1(4) NMP(67) 3 Powder 2(11) Packing 1(11) PI1(7) Surfactant 1(4) NMP(67) 4 Powder 2(11) Packing 1(2) PI1(7) Surfactant 1(4) NMP(75) 5 Powder 4(11) Packing 1(11) PI1(7) Surfactant 1(4) NMP(67) 6 Powder 2(11) Packing 3(11) PI1(7) Surfactant 1(4) NMP(67) 7 Powder 2(11) Packing 1(11) PI1(1) Surfactant 1(4) NMP(73) 8 Powder 3(11) Packing 2(11) PI1(7) Surfactant 1(4) NMP(67) 9 Powder 1(25) Packing 4(10) PI1(1) - NMP(64) ※The values in brackets in the powder, filler and varnish type columns are the contents in the dispersion (unit: mass %).

3. Example of manufacturing a molded product Dispersion 1 is applied to the surface of a long copper foil (thickness 18 μm) using a rod coater to form a wet film. Next, the metal foil formed with the wet film is passed through a drying furnace at 120°C for 5 minutes, and dried by heating to obtain a dry film. Thereafter, the dry film is heated at 380°C for 3 minutes in a nitrogen oven. Thus, a laminate 1 having a metal foil and a polymer layer (thickness 5 μm) as a molded product on the surface of the metal foil is manufactured, wherein the polymer layer as a molded product comprises a molten calcined product of powder 1 and filler 1. Laminates 2 to 10 are manufactured in the same manner as laminate 1 except that dispersion 1 is changed to dispersions 2 to 10 respectively.

4. Evaluation 4-1. Dispersion stability of dispersion After storing dispersions 1 to 10 in a container at 25°C, visually check the dispersibility and evaluate the dispersion stability according to the following criteria. [Evaluation criteria] ◎: No aggregates were observed. ○: Fine aggregates were observed to adhere to the side wall of the container. If gently stirred, the aggregates were uniformly dispersed again. △: Aggregates were observed to precipitate at the bottom of the container. If shearing and stirring were applied, the aggregates were uniformly dispersed again. ×: Aggregates were observed to precipitate at the bottom of the container. Even if shearing and stirring were applied, the aggregates were difficult to disperse again.

4-2. Physical properties of laminates 4-2-1. Surface smoothness For the polymer layers of laminates 1 to 9, the surface smoothness was visually confirmed and evaluated according to the following criteria. [Evaluation criteria] ○: The entire surface of the polymer layer is relatively smooth. △: Concavities and convexities caused by defects in the polymer or filler are observed at the edge of the surface of the polymer layer. ×: Concavities and convexities caused by defects in the polymer or inorganic filler are observed on the entire surface of the polymer layer.

4-2-2. Linear expansion coefficient For laminates 1 to 4, 9 and 10, square specimens of 180 mm were cut out and the linear expansion coefficient of the specimens within the range of 25°C to 260°C was measured according to the measurement method specified in JIS C 6471:1995. [Evaluation criteria] ○: 30 ppm/°C or less. ×: Exceeding 30 ppm/°C.

4-2-3. Dielectric loss factor For laminates 1 to 4, 9 and 10, the copper foil of the laminate was removed by etching using an aqueous solution of ferric chloride to produce a separate polymer layer, and the dielectric loss factor of the polymer layer was measured by the SPDR (split post dielectric resonator) method (measurement frequency: 10 GHz). [Evaluation criteria] ○: The dielectric loss factor of the polymer layer is less than 0.0010. △: The dielectric loss factor of the polymer layer is greater than 0.0010 and less than 0.0025. ×: The dielectric loss factor of the polymer layer exceeds 0.0025. The evaluation results are summarized in Table 2 below.

[Table 2] Dispersion number (laminated body number produced) Dispersion stability Polymer layer (molded article) Surface smoothness Linear expansion coefficient Dielectric dissipation factor Dispersion 1 (laminated body 1) ◎ ○ ○ △ Dispersion 2 (laminated body 2) ○ ○ ○ ○ Dispersion 3 (laminated body 3) ○ ○ ○ △ Dispersion 4 (laminated body 4) ○ ○ × × Dispersion 5 (laminated body 5) × × Not determined Not determined Dispersion 6 (laminated body 6) △ △ Not determined Not determined Dispersion 7 (laminated body 7) △ △ Not determined Not determined Dispersion 8 (laminated body 8) × × Not determined Not determined Dispersion 9 (laminated body 9) ○ ○ ○ ○ Dispersion 10 (laminated body 10) ◎ ○ ○ ○

5. Example of preparing dispersion (Part 2) (Example 11) First, powder 1, surfactant 1 and NMP were added to a crucible and mixed, and the mixture was stirred at 2000 rpm for 1 hour by a homogenizer to adjust the composition. Filler 1, surfactant 1 and NMP were added to another crucible, and the mixture was stirred at 2000 rpm for 1 hour by a homogenizer to adjust the composition. The mixture of the two was added to another crucible, and the mixture was stirred at 2000 rpm for 1 hour by a homogenizer to obtain dispersion 11 (viscosity: 300 mPa・s, component dispersion ratio: 80%) containing powder 1 (11 parts by mass), filler 1 (11 parts by mass), surfactant 1 (4 parts by mass) and NMP (74 parts by mass). (Example 12) Dispersion 12 (viscosity: 300 mPa・s, component dispersion ratio: 50%) was obtained in the same manner as in Example 11 except that an ultrasonic homogenizer without stirring blades was used instead of the homogenizer.

6. Example of manufacturing a laminate (Part 2) The dispersion 11 was applied to the surface of an aluminum foil having a thickness of 18 μm by roll-to-roll method to form a liquid coating. Next, the aluminum foil having the liquid coating was passed through a drying furnace at 120°C for 5 minutes and dried by heating. Thereafter, the dried coating was heated at 340°C for 3 minutes in a far infrared oven under a nitrogen atmosphere. Thus, a laminate 11 having a polymer layer (thickness: 10 μm) formed on the surface of the aluminum foil was manufactured. Furthermore, a laminate 12 was manufactured in the same manner as the laminate 11 except that the dispersion 12 was used instead of the dispersion 11. By observing the cross-section of each laminate using SEM, it was found that regarding the distribution of filler 1, the polymer layer of laminate 11 was denser than the polymer layer of laminate 12. In addition, the dielectric dissipation factor of the polymer layer of laminate 11 was lower than that of the polymer layer of laminate 12. The thermal conductivity and bendability of laminate 11 were better than those of laminate 12. [Industrial Applicability]

The dispersion of the present invention has excellent dispersion stability and can be used to produce molded products (films, impregnated products such as prepregs, laminates, coatings, etc.) having physical properties based on F polymers (PFA-based polymers) and characteristics based on anisotropic fillers. The molded products of the present invention are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, coatings, cosmetics, etc. Specifically, they are useful as heat dissipation components, wire coating materials (wires for aircraft, etc.), electrical insulating tapes, insulating tapes for oil drilling, printed circuit board materials, separation membranes (precision filter membranes, superfilter membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode adhesives. It is useful for coating materials of rollers, furniture, car dashboards, home appliances, sliding parts (load bearings, sliding shafts, valves, bearings, gears, cams, conveyor belts, food conveyor belts, etc.), tools (shovels, files, cones, saws, etc.), boilers, hoppers, pipes, ovens, pancake molds, chutes, molds, toilets, containers, heat exchangers (wings, heat transfer tubes, etc.) for cooling and heating machines, etc.

Claims (14)

A dispersion liquid comprising a tetrafluoroethylene polymer powder, an anisotropic filler having a Mohs hardness of 4 or less, and a liquid dispersion medium, wherein the tetrafluoroethylene polymer contains a unit based on perfluoro(alkyl vinyl ether) or a unit based on hexafluoropropylene, and the average particle size of the powder is smaller than the average particle size of the anisotropic filler, the anisotropic filler is an anisotropic filler containing boron nitride or talc, the content of the anisotropic filler is 10% by mass or more, and the sum of the content of the tetrafluoroethylene polymer and the content of the anisotropic filler is 60% by mass or less. Such as the dispersion of claim 1, wherein the content of the above-mentioned tetrafluoroethylene polymer is 5% by mass or more. For example, the dispersion of claim 1 or 2, wherein the anisotropic filler is in the shape of scale or plate. The dispersion of claim 1 or 2, wherein the aspect ratio of the anisotropic filler is greater than 2. The dispersion of claim 1 or 2 further comprises polytetrafluoroethylene powder or aromatic polymer. For the dispersion liquid in claim 1 or 2, the dispersion layer ratio of its components is more than 60%. A method for producing a dispersion, which is a method for producing a dispersion as in any one of claims 1 to 6, the method comprising mixing the above-mentioned powder, the above-mentioned anisotropic filler, an inorganic filler having an average particle size smaller than that of the above-mentioned anisotropic filler, and a liquid dispersion medium. In the manufacturing method of claim 7, the mixing is performed by stirring. A molded article, comprising a tetrafluoroethylene polymer containing a unit based on perfluoro(alkyl vinyl ether) and an anisotropic filler having a Mohs hardness of 4 or less, wherein the tetrafluoroethylene polymer is a polymer having a polar functional group, or a polymer containing 2.0 to 5.0 mol% of the unit based on perfluoro(alkyl vinyl ether) and not having a polar functional group relative to the total unit, the ratio of the anisotropic filler in the molded article is 10% by mass or more, and the anisotropic filler is an anisotropic filler containing boron nitride or talc. As in claim 9, the molded article, wherein the aspect ratio of the anisotropic filler is greater than 2. The molded article of claim 10, wherein the anisotropic filler is a scaly anisotropic filler containing boron nitride or a plate-like anisotropic filler containing talc. A molded article as claimed in any one of claims 9 to 11, wherein the average particle size of the anisotropic filler is greater than 1 μm. A shaped article as claimed in any one of claims 9 to 11, further comprising polytetrafluoroethylene or an aromatic polymer. A formed article as claimed in any one of claims 9 to 11, wherein the formed article is a layered formed article having a thickness of less than 150 μm.