Modified powder manufacturing method

Abstract

To provide a method for producing modified powder of hot-melt tetrafluoroethylene polymers with excellent dispersion stability, uniformity and handleability, and a method for producing a liquid composition that comprises the modified powder and a liquid dispersion medium, with excellent dispersion stability, uniformity and handleability.SOLUTION: A method for producing modified powder includes agitating powder comprising particles of hot-melt tetrafluoroethylene polymers with an average particle size of 20 μm or less with an agitator having the action of rotation and revolution to produce the modified powder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a modified powder of a tetrafluoroethylene-based polymer, a method for producing a liquid composition containing such a modified powder, and such a modified powder. [Background technology]

[0002] 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. For example, tetrafluoroethylene-based polymer powders are directly molded into molded products, or are added to other resin varnishes for use. Patent Document 1 proposes a powder composed of particles of a specific tetrafluoroethylene-based polymer as such a powder. Furthermore, a dispersion in which tetrafluoroethylene polymer powder is dispersed in particulate form in a liquid dispersion medium is used as a coating agent that imparts the above physical properties to the surface of a substrate, and since it can form molded articles with excellent electrical properties such as low dielectric constant and low dielectric loss tangent, it has attracted attention as a material for forming the dielectric layer of a printed circuit board that is compatible with frequencies in the high frequency band. 2 The document describes a dispersion of polytetrafluoroethylene particles having a particle size of 1 μm or less and a particle diameter of 1 μm or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016-017801 [Patent Document 2] Japanese Patent Application Publication No. 2017-088861 Summary of the Invention [Problem to be solved by the invention]

[0004] Tetrafluoroethylene-based polymers do not easily interact with other components and generally have low dispersion stability in liquid. Patent Document 2 describes that when the average particle size exceeds 1 μm, the dispersion stability of the dispersion decreases, and the present inventors have recognized the problem that the dispersion stability of a dispersion of tetrafluoroethylene-based polymer particles is easily affected by the polymer type and particle shape. As a result of intensive research, the present inventors have found that by treating a powder consisting of particles of a heat-fusible tetrafluoroethylene-based polymer having a specific particle size under conditions that impart a specific effect to the powder, a modified powder excellent in dispersion stability, uniformity, and ease of handling can be obtained.Furthermore, they have found that a liquid composition obtained from such modified powder is suitable for forming a dense molded product excellent in low dielectric loss tangent, low linear expansion, etc. The object of the present invention is to provide a method for producing a modified powder of a heat-fusible tetrafluoroethylene polymer, which has excellent dispersion stability, uniformity, and ease of handling, and a method for producing a liquid composition containing the modified powder and a liquid dispersion medium, which has excellent dispersion stability, uniformity, and ease of handling. Another object of the present invention is to provide a powder with specific properties, which is preferably a modified powder of a heat-fusible tetrafluoroethylene polymer obtained by the production method of the present invention. [Means for solving the problem]

[0005] The present invention has the following aspects. <1> A method for producing a modified powder, in which a powder consisting of particles of a heat-fusible tetrafluoroethylene-based polymer with an average particle size of 20 μm or less is stirred in a stirring device equipped with rotation and revolution functions to obtain a modified powder. <2> The melting temperature of the tetrafluoroethylene-based polymer is 200°C or higher and 320°C or lower. <1> Manufacturing method. <3> The tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having an oxygen-containing polar group containing a unit based on perfluoro(alkyl vinyl ether). <1> or <2> Manufacturing method. <4> The stirring device is any one of the stirring devices 1) to 6) below: <1> ~ <3> A manufacturing method of any of the above. 1) Agitation equipment equipped with a stirring tank equipped with a rotational and revolutional stirring mechanism 2) A stirring device equipped with a conical vessel that narrows downward and a spiral blade that rotates and revolves within the conical vessel. 3) Agitation equipment with multiple agitating blades that perform planetary motion 4) A flow-type agitator having an agitator blade with a drive shaft that penetrates vertically through the center of the bottom of the agitator tank. 5) A stirring device with a conical inner wall and a stirring blade with a drive shaft that penetrates vertically through the center of the tank bottom. 6) A cylindrical agitator having a cylindrical container that can rotate around the central axis as a rotation axis, and having a plurality of ribbon-screw-like outer blades that screw along the inner wall inside the cylindrical container, and a plurality of ribbon-screw-like inner blades that are disposed inside the outer blades and screw in the opposite direction to the outer blades. <5> The stirring treatment is carried out by a stirring device having a stirring tank equipped with a stirring mechanism that rotates and revolves, or a flow-type stirring device having a stirring blade with a drive shaft that vertically penetrates the center of the bottom of the stirring tank. <1> ~ <4> A manufacturing method of any of the above. <6> The stirring treatment is carried out in a stirring tank equipped with a stirring mechanism that rotates and revolves, under conditions where the revolution speed is more than 1 time the rotation speed. <5> Manufacturing method. <7> The peripheral speed of the rotation speed or revolution speed in the stirring tank equipped with the stirring mechanism by rotation and revolution, or the peripheral speed of stirring in the flow type stirring device, is 1 m / s or more and 100 m / s or less. <5> or <6> Manufacturing method. <8> 8. The method according to claim 1, wherein the stirring treatment is carried out with a filling amount of the powder of 50% by volume or less of the capacity of the stirring device. <9> the powder is formed by pulverizing granules of a heat-fusible tetrafluoroethylene-based polymer obtained by radical polymerization in a polymerization medium; <1> ~ <8> A manufacturing method of any of the above. <10> The specific surface area of ​​the powder is 8m 2 / g or less, and the specific surface area of ​​the modified powder is 90% or less of that of the powder. <1> ~ <9> A manufacturing method of any of the above. <11> The tap density of the powder is 0.3 g / ml or more, and the tap density of the modified powder is 1.2 times or more that of the powder. <1> ~ <10> A manufacturing method of any of the above. <12> The ratio of the average particle size of the modified powder to the average particle size of the powder is 0.95 or more. <1> ~ <11> A manufacturing method of any of the above. <13> A method for producing a liquid composition, comprising: stirring a powder consisting of particles of a heat-fusible tetrafluoroethylene-based polymer having an average particle size of 20 μm or less in a stirring device having rotation and revolution functions to obtain a modified powder; and mixing the modified powder with a liquid dispersion medium to obtain a liquid composition. <14> Average particle size is 20 μm or less, specific surface area is 8 m 2 A powder having a tap density of 0.3 g / ml or more, which is composed of particles of a heat-fusible tetrafluoroethylene polymer having a tap density of 0.3 g / ml or less. <15> <1> ~ <12> A modified powder obtained by any one of the methods described above. <14> Powder. [Effects of the Invention]

[0006] The present invention provides a method for producing a modified powder of a heat-fusible tetrafluoroethylene-based polymer, which has excellent dispersion stability, uniformity, and ease of handling, and a method for producing a liquid composition containing the modified powder and a liquid dispersion medium, which has excellent dispersion stability, uniformity, and ease of handling. Such a liquid composition has excellent physical properties such as electrical properties, and is useful, for example, as a constituent material for printed circuit boards. Furthermore, according to the present invention, there is provided a powder having specific properties, which is preferably a modified powder of a heat-fusible tetrafluoroethylene polymer obtained by the above-mentioned production method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] The following terms have the following meanings: "Average particle size (D50)" is the volume-based cumulative 50% diameter of a target object (particle) determined by laser diffraction / scattering. In other words, particle size distribution is measured by laser diffraction / scattering, and a cumulative curve is calculated with the total volume of the target object group as 100%. The particle size is the point on that cumulative curve where the cumulative volume is 50%. The D50 of a target object is determined by dispersing the target object in water and analyzing it by the laser diffraction / scattering method using a laser diffraction / scattering particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.). "Hot-melt resin" means a resin with melt fluidity that has a temperature at which the melt flow rate is 1 g / 10 min or more and 1000 g / 10 min or less at a temperature 20°C or more higher than the melting temperature of the resin under a load of 49 N. "Non-thermofusible resin" means a non-melt flowable resin that does not have a temperature at which the melt flow rate is 1 g / 10 min or more and 1000 g / 10 min or less under a load of 49 N. The "melting temperature of a polymer" is the temperature corresponding to the maximum value of the melting peak of the polymer as measured by differential scanning calorimetry (DSC). The "glass transition temperature (Tg) of a polymer" is a value measured by analyzing a polymer using dynamic mechanical analysis (DMA). Unless otherwise specified, the "viscosity" refers to the viscosity of a liquid composition measured using a Brookfield viscometer at 25°C and a rotation speed of 30 rpm. The measurement is repeated three times, and the average value of the three measured values ​​is used. The "thixotropy ratio" is a value calculated by dividing the viscosity η1 of a liquid composition measured at a rotation speed of 30 rpm by the viscosity η2 measured at a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average value of the three measurements is used. The term "unit" in a polymer refers to an atomic group based on a monomer formed by polymerization of the monomer. The unit may be a unit formed directly by a polymerization reaction, or may be a unit in which a portion of the unit is converted into a different structure by processing the polymer. Hereinafter, a unit based on monomer a will also be referred to simply as a "monomer a unit."

[0008] The manufacturing method of the present invention (hereinafter also referred to as "this method") is a method in which a powder (hereinafter also referred to as "raw powder") consisting of particles (hereinafter also referred to as "F particles") of a heat-fusible tetrafluoroethylene-based polymer (hereinafter also referred to as "F polymer") having an average particle diameter of 20 μm or less is stirred in a stirring device equipped with rotation and revolution functions to obtain a modified powder (hereinafter also referred to as "this modified powder"). The modified powder has excellent dispersibility, uniformity, and ease of handling, and can be used to obtain a liquid composition with excellent dispersion stability. The reasons for this are not entirely clear, but are presumed to be as follows.

[0009] F polymer has low dispersibility in liquid due to its low surface energy. When a powder of F polymer is dispersed in a liquid to prepare a liquid composition in which F polymer particles are dispersed, if a strong shear force is applied to improve the dispersibility, the F polymer is degraded by fibrillation or the like, forming complex secondary particles that tend to aggregate. This method involves agitating a powder (raw powder) composed of F particles using a stirring device equipped with rotation and revolution. In other words, the raw powder is agitated in a dry state. The powder obtained by this method (modified powder) maintains the average particle size of the original powder while exhibiting a reduced specific surface area and improved tap density compared to the original powder. This is presumably because the agitation process in this method promotes uniform collisions between F particles using moderate stress due to rotation and revolution. As a result, the modified powder is believed to have a homogenized shape while suppressing further pulverization and deformation of the original powder, resulting in a powder with excellent dispersion stability, uniformity, and ease of handling. Furthermore, the modified powder is believed to have produced a liquid composition capable of forming molded products with excellent electrical properties.

[0010] The F polymer in the present invention is a heat-meltable polymer containing units (hereinafter also referred to as "TFE units") based on tetrafluoroethylene (hereinafter also referred to as "TFE"). The melting temperature of the F polymer is preferably 200°C or higher, more preferably 240°C or higher, and even more preferably 260°C or higher. The melting temperature of the F polymer is preferably 325°C or lower, more preferably 320°C or lower. The melting temperature of the F polymer is particularly preferably 200°C or higher and 320°C or lower. In this case, deformation of the modified powder due to the heat generated during the stirring treatment is more likely to be suppressed.

[0011] The glass transition point of the F polymer is preferably 50° C. or higher, more preferably 75° C. or higher. The glass transition point of the F polymer is preferably 150° C. or lower, more preferably 125° C. or lower. In this case, deformation of the modified powder due to heat generated during the stirring process is more likely to be suppressed. The surface tension of the F polymer is preferably 16 mN / m or more and 26 mN / m or less, and more preferably 16 mN / m or more and 20 mN / m or less. The surface tension of the F polymer can be measured by placing a droplet of a wettability index reagent (manufactured by Wako Pure Chemical Industries, Ltd.) on a flat plate made of the F polymer. The fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72% by mass or more and 76% by mass or less. F polymers with a high fluorine content have excellent physical properties such as electrical properties, but have low surface tension and are more likely to have poor dispersion stability. However, for the reasons described above, the dispersion stability of such F polymers is likely to be improved in the present modified powder.

[0012] F polymer can be enumerated as polytetrafluoroethylene (PTFE), the polymer that comprises TFE unit and the unit based on ethylene, the polymer that comprises TFE unit and the unit based on propylene, the polymer that comprises TFE unit and the unit based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE unit) (PFA), the polymer that comprises TFE unit and the unit based on hexafluoropropylene (FEP), the polymer that comprises TFE unit and the unit based on fluoroalkylethylene, the polymer that comprises TFE unit and the unit based on chlorotrifluoroethylene, preferably PFA or FEP, more preferably PFA.Above-mentioned polymer can further comprise the unit based on other comonomer. As PAVE, CF2=CFOCF3, CF2=CFOCF2CF3 or CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE") is preferred, and PPVE is more preferred.

[0013] The F polymer preferably has an oxygen-containing polar group, which facilitates the formation of microspherulites at the molecular aggregate level, improves the wettability of the F particles, and makes it easier to achieve the effects of the present invention described above. The oxygen-containing polar group may be contained in a unit in the F polymer or in a terminal group of the main chain of the F polymer. Examples of the latter include an F polymer having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and an F polymer having an oxygen-containing polar group obtained by subjecting an F polymer to plasma treatment or ionizing radiation treatment. The oxygen-containing polar group is preferably a hydroxyl group-containing group, a carbonyl group-containing group, or a phosphono group-containing group. From the viewpoint of the dispersion stability of the present modified powder, a hydroxyl group-containing group and a carbonyl group-containing group are more preferred, and a carbonyl group-containing group is even more preferred.

[0014] The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF2CH2OH or -C(CF3)2OH. The carbonyl group-containing group is a group containing a carbonyl group (>C(O)), and is preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH2), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.), or a carbonate group (-OC(O)O-), with an acid anhydride residue being more preferred. In this case, the F particles are more likely to interact with the present particles and the liquid dispersion medium, and the liquid composition prepared from the present modified powder is more likely to have excellent dispersion stability, etc.

[0015] The F polymer is preferably a polymer having a carbonyl group-containing group containing TFE units and PAVE units, more preferably a polymer containing units based on a monomer having TFE units, PAVE units, and a carbonyl group-containing group, and even more preferably a polymer containing these units in the following amounts relative to the total units, in that order: 90 to 99 mol%, 0.5 to 9.97 mol%, and 0.01 to 3 mol%. The presence of a carbonyl group-containing group is preferred from the viewpoint of further improving the affinity and adhesion of the F polymer.

[0016] When the F polymer has a carbonyl group-containing group, the number of carbonyl group-containing groups in the F polymer is 1×10 6 Preferably, the number is 10 to 5000, more preferably 100 to 3000, and even more preferably 800 to 1500. 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 WO 2020 / 145133. The monomer having a carbonyl group-containing group is preferably itaconic anhydride, citraconic anhydride, or 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"). Specific examples of such polymers include the polymers described in WO 2018 / 16644.

[0017] The raw powder in this method is a powder formed from an F polymer. The raw powder may be a granulated product of the F polymer. The granulated product may be a powder formed by agglomerating individual F polymer particles (primary particles) constituting the powder, or may be a powder formed by mechanically pulverizing such a powder. The former powder is preferably a powder obtained by agglomerating an F polymer dispersed as primary particles in a polymerization medium, which is obtained by radical polymerization of TFE and other monomers copolymerizable with TFE in the polymerization medium. In other words, the agglomerated powder is preferably a powder obtained by agglomerating an F polymer dispersed as primary particles in a polymerization medium by the action of a flocculant or shear stirring. The mechanical pulverization in the preparation of the latter powder is preferably carried out using a mechanical pulverizing device such as a hammer mill, a pin mill, a disk mill, a rotary mill, or a jet mill.

[0018] In this method, the raw powder is a powder consisting of F particles having an average particle size (D50) of 20 μm or less. The D50 of the F particles is preferably less than 10 μm, more preferably 8 μm or less. The D50 of the F particles is preferably 0.5 μm or more, more preferably more than 1 μm. With a D50 in this range, the flowability and dispersion stability of the F particles tend to be good. The raw powder may contain other components such as inorganic substances in addition to the F polymer, but it is preferable that the F polymer is the main component. Examples of inorganic substances include silicon oxide (silica), metal oxides (beryllium oxide, cerium oxide, alumina, soda alumina, magnesium oxide, zinc oxide, titanium oxide, etc.), boron nitride, and magnesium metasilicate (steatite). The inorganic substances are preferably contained in the F particles as inorganic particles, and at least a portion of the surface of the inorganic particles may be surface-treated. The content of the F polymer in the raw powder is preferably 80% by mass or more, more preferably 100% by mass.

[0019] When the raw powder contains F particles and inorganic particles, the F particles may have a core-shell structure with an F polymer as the core and inorganic particles as the shell, or may have a core-shell structure with an F polymer as the shell and inorganic particles as the core. Such F particles can be obtained, for example, by coalescence (collision, aggregation, etc.) of an F polymer powder and inorganic particles.

[0020] From the viewpoint of dispersion stability of this modified powder in the liquid composition described later, the specific surface area of ​​the original powder (F particles) is 25 m 2 / g or less, and 2 / g or less is more preferable. The specific surface area of ​​the raw powder is 1m 2 / g or more is preferred. The tap density of the raw powder is preferably 0.3 g / ml or more.

[0021] One type of F particle may be used, or two or more types may be used.

[0022] In this method, the stirring device having rotation and revolution functions is preferably any one of the stirring devices 1) to 6) below.

[0023] 1) A stirring device equipped with a stirring tank equipped with a stirring mechanism that rotates and revolves (hereinafter also referred to as "stirring device 1") The rotational stirring mechanism in the stirring vessel provided in the stirring device 1 is a mechanism in which the stirring vessel containing the material to be stirred (raw powder) rotates around a rotation axis to stir the material. The direction of the rotation axis may be in either direction relative to the stirring vessel. On the other hand, the revolutional stirring mechanism is a mechanism in which the stirring vessel revolves around a fixed point outside the stirring vessel containing the material to be stirred, thereby stirring the material. The stirring vessel may be vertical, horizontal, or inclined relative to the plane of revolution. Such a stirring device is sometimes called a rotational-revolution mixer. The stirring device 1 may be, for example, the "Awatori Rentaro (registered trademark)" series manufactured by Thinky Corporation.

[0024] 2) A stirring device (hereinafter also referred to as "stirring device 2") equipped with a conical vessel that narrows downward and a spiral blade that rotates and revolves within the conical vessel. The spiral blades provided in the stirring device 2 extend in the conical tank at an incline parallel to the inner wall of the conical tank, rotate around an axis of rotation that is inclined parallel to the inner wall of the conical tank, and revolve around the central axis of the conical tank along the inner wall of the conical tank. In the agitator 2, the spiral impeller rotates, causing the material to flow upward along the inner wall of the conical vessel. At the same time, the spiral impeller revolves, causing a horizontal spiral flow within the vessel, causing the material to fall within the vessel. In this way, the planetary motion of the spiral impeller lifts the material from below upward, repeatedly stirring and dispersing it, resulting in a high level of agitation throughout the entire vessel. Examples of the agitator 2 include "NVB Mixer" manufactured by Nishimura Machinery Works, Ltd. and "Nauta Mixer" manufactured by Hosokawa Micron Corporation.

[0025] 3) A stirring device in which multiple stirring blades perform planetary motion (hereinafter also referred to as "stirring device 3") The stirring vessel of the stirring device 3 preferably has a shape with no stagnation areas and curved corners. The multiple stirring blades that perform planetary motion are preferably two stirring blades that are close to the inner wall of the stirring vessel. Examples of the shape of the stirring blades include hooks, spiral hooks, beaters, and screw beaters. It is preferable that the two agitator blades rotate in opposite directions. The agitator blade that rotates in the same direction as the revolution direction presses the material being agitated over a wide area against the inner wall of the agitator vessel, applying a shearing action over a wide area. The agitator blade that rotates in the opposite direction to the revolution direction has the effect of scraping the material being agitated from the inner wall of the agitator vessel. An example of the agitator 3 is a planetary mixer. A planetary mixer has two agitating blades that rotate and revolve around each other, and is designed to agitate the material to be agitated in the agitation tank. As a result, there is little dead space in the agitation tank where the agitating blades do not reach, reducing the load on the blades and allowing the material to be agitated to a high degree.

[0026] 4) A flow-type agitator having an agitating blade with a drive shaft that penetrates vertically through the center of the bottom of the agitation tank (hereinafter also referred to as "agitator 4"). The material to be stirred that is put into the stirring device 4 is pressed against the inner wall of the stirring tank by the rotational force of the stirring blades at the bottom of the tank, and then peeled off from the wall and dispersed, and then rotated by the revolution action inside the tank caused by the stirring blades being lifted up.This series of movements is repeated to stir the material to be stirred. The tip of the stirring blade may have a spherical, oval or cylindrical shape in order to increase its cross-sectional area. Examples of the stirring device 4 include the "NSM" series manufactured by Seishin Enterprise Co., Ltd. and the "Kryptron Orb" series manufactured by Earth Technica Corporation. A specific example of the agitator 4 is a Henschel mixer, which is an agitator having a mixing mechanism in which the material to be agitated rises from the bottom of the tank along the side wall while being agitated by the rotation of the agitating blades rotating at high speed, and then falls from the center of rotation to the bottom of the tank by the revolution, causing the input material to become fluidized together with air and to circulate repeatedly.

[0027] 5) A stirring device having a conical inner wall surface and a stirring blade with a drive shaft that penetrates vertically through the center of the tank bottom (hereinafter also referred to as "stirring device 5"). The stirring tank of the stirrer 5 is typically a conical tank having an inverted cone shape. The stirring blades of the stirrer 5 may be ribbon blades having, for example, a double-spiral structure or a single-spiral structure. The material to be stirred supplied to the conical tank is subjected to rotation along the inner peripheral wall surface of the cone by the rotation of the stirring blades, and also subjected to revolution that lifts the material from below upward, whereby stirring and dispersion are repeated, and the material to be stirred is subjected to a stirring treatment. An example of the stirring device 5 is "Rebocone" manufactured by Okawara Manufacturing Co., Ltd.

[0028] 6) A cylindrical agitator having a cylindrical container that can rotate around a central axis as a rotation axis, with multiple ribbon screw-shaped outer blades that screw along the inner wall of the cylindrical container, and multiple ribbon screw-shaped inner blades that are disposed inside the outer blades and screw in the opposite direction to the outer blades (hereinafter also referred to as "agitator 6"). The cylindrical container in the agitator 6 is arranged such that the central axis serving as the rotation axis is horizontal to the ground surface, for example, and has a raw material supply port and a discharge port for discharging the raw material after the agitation is completed. As the cylindrical container of the agitator 6 rotates clockwise as viewed from the discharge port, the material to be stirred that is introduced is moved by the ribbon screw-shaped outer blades, with the material closest to the inner wall of the cylindrical container being revolved from the discharge port toward the raw material supply port. Meanwhile, the inner blades impart a rotational force to the material to be stirred as the cylindrical container rotates around its central axis, moving the material from the raw material supply port to the discharge port. This operation is repeated to stir the material to be stirred.

[0029] From the viewpoint of stirring efficiency and good progress of raw powder modification, the stirring treatment is preferably carried out with the raw powder filling amount being 50% by volume or less, more preferably 30% by volume or less, of the capacity of the stirring device. The stirring treatment can be carried out either batchwise or continuously. In the case of a continuous method, a stirring device equipped with a stirring tank having a discharge port for the stirred product may be used, and the stirred product removed from the discharge port may be supplied again from an inlet and mixed, or multiple stirring tanks may be used, and the mixture removed from the discharge port of a previous stirring tank may be supplied to the inlet of a subsequent stirring tank and mixed.

[0030] In this method, it is preferable to carry out the stirring treatment of the raw powder using the stirring device 1 or the stirring device 4 from the viewpoint of the dispersibility, uniformity and ease of handling of the resulting modified powder. When the raw powder is stirred using the stirring device 1, the stirring is preferably carried out in a stirring tank equipped with a stirring mechanism that rotates and revolves, under conditions where the revolution speed is more than 1 time the rotation speed. The stirring is preferably carried out under conditions where the revolution speed is 10 times or less the rotation speed. In this case, the present modified powder having excellent dispersibility and dispersion stability is easily obtained.

[0031] From the same viewpoint, it is preferable that the peripheral speed of the rotation speed or revolution speed of the agitator 1, or the peripheral speed of agitation in the agitator 4, is 1 m / s or more and 100 m / s or less. Furthermore, in the stirring device 1, it is preferable that the peripheral speed of the rotation speed is 1 m / s or more and 10 m / s or less, and the peripheral speed of the revolution speed is 10 m / s or more and 30 m / s or less, from the viewpoint of significantly expressing the above-mentioned mechanism of action. The rotation speed of the stirring blades in the stirring device 4 is preferably 10 m / s or more and 100 m / s or less, from the viewpoint of improving the rotation and revolution effects and significantly exhibiting the above-mentioned mechanism of action.

[0032] The stirring time is preferably 5 minutes or more, more preferably 30 minutes or more. The stirring time is preferably 120 minutes or less, more preferably 90 minutes or less. If the stirring time is within this range, it is easy to balance sufficient modification of the raw powder with the productivity of the modified powder.

[0033] In this method, the original powder is stirred using a stirring device with rotation and revolution functions, which increases the tap density of the original powder and allows the production of a modified powder that largely maintains the average particle size of the original powder. The ratio of the average particle size (D50) of the modified powder to the average particle size (D50) of the original powder is preferably 0.95 or more. The upper limit of this ratio is 1. Specifically, the D50 of the modified powder is 20 μm or less, preferably less than 10 μm. The D50 is preferably 0.5 μm or more, more preferably more than 1 μm.

[0034] The specific surface area of ​​the modified powder is preferably 90% or less of that of the original powder. Also, the specific surface area of ​​the modified powder is preferably 75% or more of that of the original powder. Specifically, the specific surface area of ​​the modified powder is 25 m 2 / g or less is preferable, and 8m 2 / g or less is more preferable. The specific surface area of ​​the modified powder is 1m 2 If the specific surface area of ​​the present modified powder is within this range, the dispersion stability of a liquid composition prepared from the present modified powder and the physical properties of a molded product prepared from a liquid composition containing the present modified powder are likely to be further improved.

[0035] The tap density of the modified powder is preferably 1.2 times or more that of the original powder. The tap density of the modified powder is preferably 1.5 times or less that of the original powder. Specifically, the tap density of the original powder is preferably 0.3 g / ml or more, and the tap density of the modified powder obtained by the present method is preferably 0.36 g / ml or more. The tap density can be determined by the method described in the Examples. If the tap density of the present modified powder is within this range, the present modified powder is less likely to aggregate, and has better dispersibility. In addition, the efficiency of transfer, storage, transportation, etc. is excellent, and handling is easy.

[0036] By mixing the present modified powder with a liquid dispersion medium, a liquid composition containing the present modified powder and the liquid dispersion medium (hereinafter also referred to as "the present composition") is obtained. The present modified powder is preferably dispersed in the liquid dispersion medium. The content of the modified powder in the composition is preferably 10% by mass or more, more preferably 25% by mass or more, based on the total mass of the composition, and is preferably 95% by mass or less, more preferably 75% by mass or less, based on the total mass of the composition.

[0037] Methods for mixing the modified powder with a liquid dispersion medium include stirring using a stirring device equipped with blades (stirring blades) such as propeller blades, turbine blades, paddle blades, and shell-shaped blades, either uniaxially or multiaxially, or a Henschel mixer, pressure kneader, Banbury mixer, or planetary mixer; mixing using a disperser that uses media such as a ball mill, attritor, basket mill, sand mill, sand grinder, Dynomill (a bead mill using a grinding medium such as glass beads or zirconium oxide beads), Dispermat, SC mill, spike mill, or agitator mill; mixing using a disperser that does not use media, such as a high-pressure homogenizer such as a microfluidizer, nanomizer, or ultimizer, an ultrasonic homogenizer, a dissolver, a disperser, a high-speed impeller disperser, a thin film swirling high-speed mixer, or a planetary mixer. Examples include mixing using a Henschel mixer, pressure kneader, Banbury mixer, planetary mixer, or planetary mixer, with a planetary mixer being more preferred.

[0038] The liquid dispersion medium contained in the composition is a compound that is liquid at atmospheric pressure and 25°C. The liquid dispersion medium may be water or a non-aqueous dispersion medium. Furthermore, the liquid dispersion medium may be an aprotic dispersion medium or a protic dispersion medium. The liquid dispersion medium is preferably selected from the group consisting of water, amides, ketones and esters. Examples of amides include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropanamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-diethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone. Examples of ketones include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, 2-heptanone, cyclopentanone, cyclohexanone, and cycloheptanone. Examples of the ester include methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl 3-ethoxypropionate, γ-butyrolactone, and γ-valerolactone. The content of the liquid dispersion medium in the composition is preferably 5% by mass or more, more preferably 25% by mass or more, based on the total mass of the composition, and is preferably 90% by mass or less, more preferably 75% by mass or less.

[0039] The composition may further contain a surfactant, which is preferably a nonionic surfactant. The nonionic surfactant is preferably a glycol monoalkyl ether, an acetylene-based surfactant, a silicone-based surfactant, or a fluorine-based surfactant, and more preferably a glycol monoalkyl ether or a silicone-based surfactant. The composition may contain a silicone-based surfactant and a glycol monoalkyl ether.

[0040] Specific examples of nonionic surfactants include the "Ftergent" series (manufactured by Neos Corporation, Ftergent is a registered trademark), the "Surflon" series (manufactured by AGC Seimi Chemical Co., Ltd., Surflon is a registered trademark), the "Megafac" series (manufactured by DIC Corporation, Megafac is a registered trademark), the "Unidyne" series (manufactured by Daikin Industries, Ltd., Unidyne is a registered trademark), "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", "BYK-3456" (manufactured by BYK Japan Co., Ltd.), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), the "Tergitol" series (manufactured by The Dow Chemical Company, "Tergitol TMN-100X", etc.), "Lutensol T08", "Lutensol XL70", "Lutensol XL80", "Lutensol XL90", "Lutensol Examples of such surfactants include "XP80" and "Lutensol M5" (both manufactured by BASF), "Newcol 1308FA" and "Newcol 1310" (both manufactured by Nippon Nyukazai Co., Ltd.), "Leocol TDN-90-80" and "Leocol SC-90" (both manufactured by Lion Specialty Chemicals). When the present composition contains a surfactant, the content of the surfactant in the present composition is preferably from 0.1% by mass to 15% by mass, and more preferably from 1% by mass to 10% by mass. The present composition containing the present modified powder has low viscosity and excellent dispersibility due to the excellent dispersion stability and uniformity of the present modified powder, even when the surfactant content is reduced.

[0041] The composition may further contain inorganic particles. The inorganic particles are preferably nitride particles or inorganic oxide particles, more preferably boron nitride particles, beryllia particles (beryllium oxide particles), silicate particles (silica particles, wollastonite particles, talc particles), or metal oxide particles (cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.), still more preferably boron nitride particles and silica particles, and particularly preferably silica particles.

[0042] It is preferable that at least a portion of the surface of the inorganic particles is surface-treated with a silane coupling agent (3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, etc.). The inorganic particles preferably have a D50 of 20 μm or less, more preferably 10 μm or less, and preferably have a D50 of 0.01 μm or more, more preferably 0.1 μm or more.

[0043] The shape of the inorganic particles may be any of spherical, needle-like (fibrous) and plate-like, and is preferably spherical or plate-like. Specific shapes of the inorganic particles include spherical, scale-like, layer-like, leaf-like, apricot-like, columnar, cockscomb-like, equiaxial, leaf-like, micaceous, block-like, tabular, wedge-like, rosette-like, net-like, and prismatic shapes. The inorganic particles may be used alone or in combination of two or more types. When the composition further contains inorganic particles, the amount thereof is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, based on the total mass of the composition.

[0044] Specific examples of suitable inorganic particles include silica particles (such as the "Admafine (registered trademark)" series manufactured by Admatechs Co., Ltd.), zinc oxide particles surface-treated with an ester such as propylene glycol dicaprate (such as the "FINEX (registered trademark)" series manufactured by Sakai Chemical Industry Co., Ltd.), spherical fused silica particles (such as the "SFP (registered trademark)" series manufactured by Denka Co., Ltd.), titanium oxide particles coated with a polyhydric alcohol and an inorganic substance (such as the "Tipaque (registered trademark)" series manufactured by Ishihara Sangyo Kaisha, Ltd.), and rutile-type titanium oxide particles surface-treated with alkylsilane (such as the "Te Examples of suitable particles include the "JMT (registered trademark)" series manufactured by Ika Corporation, hollow silica particles (the "E-SPHERES" series manufactured by Taiheiyo Cement Corporation, the "Silinax" series manufactured by Nittetsu Mining Co., Ltd., and the "Ecocospher" series manufactured by Emerson & Cumming Co., Ltd.), talc particles (the "SG" series manufactured by Nippon Talc Co., Ltd., and the like), steatite particles (the "BST" series manufactured by Nippon Talc Co., Ltd., and the like), and boron nitride particles (the "UHP" series manufactured by Showa Denko KK, and the "Denka Boron Nitride" series ("GP" and "HGP" grades) manufactured by Denka Co., Ltd., and the like).

[0045] The present composition may further contain an aromatic polymer. When the present composition contains an aromatic polymer, the liquid physical properties of the present composition, such as dispersion stability, are improved, and flexibility, such as flex resistance, can be imparted to a molded product obtained from the present composition. Furthermore, when the present composition is applied to the surface of a substrate such as a polyimide film or a metal foil to form a polymer layer containing an F polymer, the aromatic polymer can impart properties such as adhesiveness and adhesion to the resin film to the polymer layer. The aromatic polymer may be thermoset or thermoplastic, may be modified, or may be included in the composition as a precursor thereof.

[0046] The average molecular weight of the aromatic polymer is preferably 5,000 or more, more preferably 10,000 or more. The average molecular weight of the aromatic polymer is preferably 50,000 or less, more preferably 30,000 or less. In this case, the aromatic polymer is easily soluble in water. Furthermore, molded articles obtained from this composition tend to have excellent mechanical properties such as flex resistance. Examples of aromatic polymers include aromatic imide resins, aromatic sulfide resins, aromatic sulfone resins, and phenol resins, with aromatic imide resins being preferred.

[0047] Examples of aromatic imide resins include aromatic polyimides, aromatic polyamideimides, aromatic polyetherimides, and precursors thereof. These may be modified and may have polar functional groups such as carboxylic acid groups. Preferred aromatic imide resins are aromatic polyimides or precursors thereof (polyamic acids or salts thereof), and aromatic polyamideimides or precursors thereof. Examples of aromatic polyimide precursors include polyamic acids obtained by polymerizing tetracarboxylic dianhydrides and diamines in a solvent, and polyamic acid salts obtained by reacting the polyamic acids with aqueous ammonia or organic amines. Examples of aromatic polyamideimides or precursors thereof include aromatic polyamideimides or precursors thereof obtained by reacting diisocyanate and / or diamine with a tribasic acid anhydride (or tribasic acid chloride) as an acid component. Specific examples of aromatic polyamideimide or precursors thereof include "HPC-1000" and "HPC-2100D" (both manufactured by Showa Denko Materials Co., Ltd.). Examples of aromatic polyetherimides include amorphous polymers having imide bonds and ether bonds in the main chain, and a polycondensate of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane and m-phenylenediamine is preferred. A specific example of aromatic polyetherimides is "Ultem 1000F3SP" (manufactured by SABIC). An example of the aromatic sulfide resin is polyphenylene sulfide. An example of the aromatic sulfone resin is polyphenylsulfone.

[0048] When the composition contains an aromatic polymer, the content thereof is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, based on the total mass of the composition, and preferably 30% by mass or less, more preferably 10% by mass or less, based on the total mass of the composition. When the composition contains an aromatic polymer, the ratio of the content of the aromatic polymer to the content of the F particles is preferably 0.001 or more, more preferably 0.005 or more, and is preferably 0.1 or less, more preferably 0.05 or less.

[0049] When the liquid dispersion medium constituting the present composition is water, it may further contain a pH adjuster or pH buffer from the viewpoint of pH adjustment. In this case, the pH of the present composition is preferably adjusted to 5 or more and 10 or less, more preferably 7 or more and 9 or less, using the pH adjuster or pH buffer. Examples of pH adjusters include amines, ammonia, and citric acid. Examples of pH buffers include tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium hydrogen carbonate, ammonium carbonate, and ammonium acetate. The pH adjuster or pH buffer may be added either before or during mixing. The composition may further be subjected to a defoaming treatment, which is preferably carried out using a planetary centrifugal mixer.

[0050] The composition may further contain particles of polytetrafluoroethylene (hereinafter also referred to as "PTFE") that do not have oxygen-containing polar groups (hereinafter also referred to as "PTFE particles"). In this case, the F polymer in the composition is moderately fibrillated while maintaining its physical properties, making it easier for the F particles to be supported in a molded product formed from the composition, and thereby favorably exhibiting physical properties inherent to PTFE, such as heat resistance. PTFE may be a homopolymer of TFE or a copolymer of TFE and a trace amount of a comonomer such as PAVE, HFP, or fluoroalkylethylene, which is called a modified PTFE. The proportion of TFE units in PTFE is 99.5 mol % or more, preferably 99.9 mol % or more, of all units. PTFE is preferably non-thermofusible. A non-thermofusible polymer means a polymer that does not have a temperature at which the melt flow rate is 1 g or more and 1000 g or less per 10 minutes under a load of 49 N. The average particle size of the PTFE particles is preferably 0.1 μm or more and 1 μm or less. When the present composition contains PTFE particles, the mass ratio of the F polymer to the PTFE particles in the present composition is preferably 1 or more and 10 or less, with the mass of the PTFE particles being 1 for the mass of the F polymer.

[0051] In addition to the above-mentioned components, the present composition may further contain a thixotropy-imparting agent, a viscosity modifier, an antifoaming agent, a plasticizer, a weather resistance agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, a colorant, a conductive agent, a release agent, a surface treatment agent, a flame retardant, an antiseptic, an antifungal agent, an organic filler, and the like. Due to the above-mentioned mechanism of action, the present composition has excellent dispersion stability, and the liquid properties can be easily adjusted by adding these.

[0052] The viscosity of the present composition is preferably 10 mPa·s or more and 10,000 mPa·s or less, and more preferably 50 mPa·s or more and 1,000 mPa·s or less. The thixotropy ratio of the present composition is preferably 1.0 or more and 3.0 or less. When the viscosity or thixotropy of the present composition is within this range, the composition is easy to handle and can be easily molded into a dense molded product. Due to the above-mentioned mechanism of action, the present composition can be easily prepared from the present modified powder.

[0053] This composition is placed on the surface of a substrate, heated to remove the liquid dispersion medium, and further heated to obtain a laminate having a substrate layer and a layer containing an F polymer on the surface of the substrate layer (hereinafter also referred to as "F layer"). This composition has excellent liquid physical properties such as dispersion stability, and due to the above-mentioned mechanism of action, it can form molded products based on the F polymer with excellent physical properties. More specifically, the composition is applied to the surface of a substrate to form a liquid coating, which is then heated to remove the dispersant to form a dry coating, and the dry coating is further heated to bake the F polymer, thereby obtaining a laminate having an F layer on the surface of the substrate layer.

[0054] Examples of the substrate include metal substrates (metal foils of copper, nickel, aluminum, titanium, alloys thereof, etc.), heat-resistant resin films (films containing one or more heat-resistant resins such as polyimide, polyarylate, polysulfone, polyarylsulfone, polyamide, polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, liquid crystalline polyester, liquid crystalline polyesteramide, and tetrafluoroethylene-based polymer, and may be single-layer or multi-layer films), prepregs (precursors of fiber-reinforced resin substrates), and glass. The metal substrate may be a low-roughening copper foil or a non-roughening copper foil. When the metal substrate is a low-roughening copper foil or a non-roughening copper foil, the laminate tends to have excellent transmission characteristics. The ten-point average roughness of the surface of the substrate is preferably 0.01 μm or more and 0.05 μm or less. The shape of the substrate may be flat, curved or irregular, and may further be any of foil, plate, film or fiber.

[0055] The method for applying the present composition to the surface of a substrate may be any method that forms a stable liquid coating (wet film) of the present composition on the surface of the substrate, and examples thereof include a coating method, a droplet ejection method, and a dipping method, with the coating method being preferred. The coating method allows for efficient formation of a liquid coating on the surface of a substrate using simple equipment. Examples of the coating method include spraying, roll coating, spin coating, gravure coating, microgravure coating, gravure offset, knife coating, kiss coating, bar coating, die coating, fountain-meyer bar coating, and slot die coating.

[0056] When drying the liquid coating, the liquid coating is heated to a temperature at which the liquid components volatilize, and a dried coating is formed on the surface of the substrate. The heating temperature for such drying is preferably 100° C. or higher and 200° C. or lower. Air may be blown onto the surface in the step of removing the liquid components. During drying, the liquid component does not necessarily have to be completely evaporated, but it is sufficient to evaporate it to an extent that the layer shape after holding is stable and a free-standing film can be maintained. When baking the F polymer, it is preferable to heat the dried coating to a temperature equal to or higher than the melting point of the F polymer, preferably 380°C or lower, more preferably 350°C or lower.

[0057] Examples of heating methods include a method using an oven, a method using a ventilation drying furnace, and a method using heat rays such as infrared rays. Heating may be performed under either 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.), or an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.). The heating time is preferably from 0.1 to 30 minutes, more preferably from 0.5 to 20 minutes. By heating under the above conditions, the F layer can be suitably formed while maintaining high productivity.

[0058] The thickness of the F layer is preferably 0.1 μm or more, more preferably 10 μm or more, and even more preferably 50 μm or more. The thickness of the F layer is preferably 500 μm or less, more preferably 250 μm or less. Because the composition has excellent physical properties such as dispersion stability, a thick F layer can be easily formed from the composition. The peel strength between the F layer and the substrate 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 composition, the present laminate can be easily formed without impairing the physical properties of the F polymer in the F layer.

[0059] The composition may be applied to only one surface of the substrate, or to both surfaces of the substrate. In the former case, a laminate having a substrate layer composed of the substrate and an F layer on one surface of the substrate layer is obtained, while in the latter case, a laminate having a substrate layer composed of the substrate and an F layer on both surfaces of the substrate layer is obtained. The latter laminate is less likely to warp, and therefore is easier to handle during processing. Specific examples of such laminates include a metal-clad laminate having a metal foil and an F layer on at least one surface of the metal foil, and a multilayer film having a polyimide film and an F layer on both surfaces of the polyimide film. These laminates are suitable as printed circuit board materials because they have excellent physical properties such as electrical properties, and can be used to manufacture flexible printed circuit boards and rigid printed circuit boards.

[0060] The present laminate having an F layer on both surfaces of a substrate layer may be obtained by applying the present composition to both surfaces of a substrate, heating to remove liquid components, and further heating to bake the F polymer, thereby simultaneously forming an F layer on both surfaces. The present laminate having an F layer on both surfaces of a substrate layer may be obtained by immersing the substrate in the present composition, applying the present composition to both surfaces of the substrate, and then passing the substrate through a firing furnace and heating it. Specifically, the present laminate may be obtained by immersing the substrate in the present composition, and then passing the substrate through a firing furnace and heating it while lifting it out of the composition. The laminate can be suitably produced using an apparatus having a dip coater and a firing furnace, such as a vertical firing furnace or a glass cloth coating machine manufactured by Tabata Kikai Kogyo Co., Ltd.

[0061] As described above, the use of this composition allows for the production of laminates with excellent component uniformity and electrical properties. This composition is particularly suitable for the roll-to-roll production of multilayer films containing F layers on both surfaces of a polyimide film. Such multilayer films can be effectively used as materials for printed wiring boards, particularly flexible printed wiring boards, and exhibit the physical properties of the F polymer well.

[0062] Furthermore, by removing the substrate from the present laminate, a sheet consisting of layer F can be produced. Methods for removal include peeling and etching. Laminates of the F layer and the substrate layer and sheets comprising the F layer are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, heat dissipation parts, paints, cosmetics, etc.

[0063] Specifically, these include electrical wire coating materials (aircraft electrical wires, etc.), enameled wire coating materials used in motors for electric vehicles, etc., electrical insulating tape, insulating tape for oil drilling, materials for printed circuit boards, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), copy rolls, covers for furniture, automobile dashboards, and home appliances, sliding parts (load bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear rings, pistons, slide switches, gears, cams, belt conveyors, food transport belts, etc.), wear pads, wear strips, tube lamps, test sockets, wafer guides, wear parts for centrifugal pumps, hydrocarbon, chemical and water supply pumps, tools (shovels, files, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, dies, toilets, container coating materials, power devices, transistors, thyristors, rectifiers, transformers, power MOS It can also be suitably used as a heat dissipation component for FETs, CPUs, heat dissipation fins, metal heat sinks, blades for wind turbines, wind power generation equipment, aircraft, etc., heat dissipation substrates for automobiles, and wireless communication devices (for example, the wireless communication devices described in WO2020 / 008691 and WO2020 / 031419).

[0064] The laminate, whose base layer is a resin film (preferably a polyimide resin film), is useful as a release film or carrier film. The laminate has excellent adhesion between the F layer and the base layer, making it difficult for delamination to occur, allowing it to be used repeatedly as a carrier film. Furthermore, the F layer has excellent heat resistance, so its release properties are unlikely to deteriorate even after repeated use. Specifically, the present laminate is useful as a carrier film for forming ceramic green sheets, a carrier film for forming secondary batteries, a carrier film for forming solid polymer electrolyte membranes, and a carrier film for forming catalysts for solid polymer electrolyte membranes.

[0065] In addition, the present composition prepared from the present modified powder is useful as a coating material for imparting low dielectric properties, insulation, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, and thermal conductivity. Specifically, the composition can be used in printed wiring boards, solder resists, thermal interface materials, power module substrates, coils used in power devices such as motors, automotive engines, heat exchangers, vials, syringes, ampoules, medical wires, secondary batteries such as lithium ion batteries, primary batteries such as lithium batteries, radical batteries, solar cells, fuel cells, lithium ion capacitors, hybrid capacitors, capacitors (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode binders, electrode separators, and electrodes (positive electrodes, negative electrodes).

[0066] The composition prepared from the modified powder is also useful as an adhesive for bonding components. Specifically, the composition can be used to bond ceramic components, metal components, electronic components such as IC chips, resistors, and capacitors on substrates for semiconductor devices and module components, circuit boards and heat sinks, and LED chips to substrates. The composition further containing a conductive filler can also be used in applications requiring electrical conductivity, such as in the field of printed electronics, including the manufacture of energized elements in printed circuit boards, semiconductor die attach materials, sensor electrodes, displays, backplanes, RFID (radio frequency identification), solar power generation, lighting, disposable electronic devices, automotive heaters, electromagnetic interference (EMI) shielding, and membrane switches.

[0067] The composition prepared from the modified powder is also useful as a fiber sizing agent. By applying the composition to the surface of a fiber and evaporating the liquid dispersion medium, a sized fiber with an F polymer attached to the surface can be obtained. After evaporating the liquid dispersion medium, the F polymer can be calcined by further heating to obtain a sized fiber with a calcined F polymer attached to the surface. Examples of fibers include glass fibers such as E glass, D glass, L glass, S glass, T glass, Q glass, UN glass, NE glass, and spherical glass; organic fibers such as aramid fibers, polyolefin fibers, modified polyphenylene ether fibers, vinylon fibers, rayon fibers, polyester fibers, and natural fibers; boron fibers, carbon fibers, and metal fibers, with carbon fibers being preferred.

[0068] The present invention also provides a method for producing a granular material having an average particle size of 20 μm or less and a specific surface area of ​​8 m 2 The powder of the present invention is a powder having a tap density of 0.3 g / ml or more, which is composed of particles of a heat-fusible tetrafluoroethylene polymer having a tap density of 0.3 g / ml or less. Such powder is preferably a modified powder obtained by the above-mentioned production method. Since the powder of the present invention has excellent uniformity, by mixing the powder of the present invention with a liquid dispersion medium, a liquid composition having excellent dispersion stability, uniformity, and handleability can be obtained. The definition and range of the heat-fusible tetrafluoroethylene polymer in the powder of the present invention, including the preferred range, are the same as those in the modified powder obtained by the present method. Furthermore, by mixing the powder of the present invention with a liquid dispersion medium, a liquid composition containing the powder of the present invention and a liquid composition can be obtained. The range and suitable content of the liquid dispersion medium and optional added components such as surfactants, inorganic particles, aromatic polymers, etc. in such a liquid composition, as well as the application mode of such a liquid composition, are the same as those in the present composition containing the modified powder and a liquid dispersion medium.

[0069] The method for producing the present modified powder, the method for producing a liquid composition containing the present modified powder, and the powder of the present invention have been described above, but the present invention is not limited to the configurations of the above-described embodiments. For example, the method for producing the present modified powder and the method for producing a liquid composition containing the present modified powder may have any other steps added to the configuration of the above embodiment, or may be replaced with any step that produces a similar effect. Furthermore, the powder of the present invention, which is preferably the present modified powder, may have any other steps added to the configuration of the above embodiment, or may be replaced with any step that exhibits a similar function. [Example]

[0070] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. 1.Details of each ingredient [Raw powder (F particles)] F particle 1: Contains 97.9 mol%, 0.1 mol%, and 2.0 mol% of TFE units, NAH units, and PPVE units, in that order, and has a carbonyl group-containing group with a main chain carbon number of 1×10 6 Particles (D50: 2.1 μm, specific surface area: 8.1 m) made of polymer (melting temperature: 300°C) with 1000 particles per particle 2 / g, tap density: 0.2g / ml) F Particle 2: Particles (D50: 2.0 μm, specific surface area: 8.2 m) made of a polymer (melting temperature: 300°C) containing 97.5 mol% TFE units and 2.5 mol% PPVE units, in that order, and having no oxygen-containing polar groups. 2 / g, tap density: 0.2g / ml) [Surfactants] Surfactant 1: Nonionic surfactant (BYK-3450 manufactured by BYK Japan Co., Ltd.)

[0071] 2. Stirring means Mixing device A: Planetary mixer (Thinky Corporation's "Awatori Rentaro (registered trademark)") (Agitation device equipped with an agitation tank equipped with an agitation mechanism that rotates and revolves) Mixing device B: Seishin Enterprise Co., Ltd. "NSM-200" (A flow-type agitator having an agitator blade with a drive shaft that passes vertically through the center of the bottom of the agitator vessel) Mixing device C: Ball mill using ceramic balls (Agitation device without rotation and revolution agitation mechanism)

[0072] 3. Examples of manufacturing modified powder and liquid compositions [Example 1] (1) The F particles 1 were stirred for 5 minutes by the stirring device A under conditions of a revolution speed of 2000 rpm and a rotation speed of 1000 rpm, to obtain modified powder 11. (2) The obtained modified powder 11, surfactant 1, and water were mixed as they were using a stirring device A to obtain a liquid composition 1 containing modified powder 11 (50 parts by mass), surfactant 1 (2.5 parts by mass), and water (47.5 parts by mass). [Example 2] The F particles 1 were stirred for 5 minutes at 6000 rpm using the stirring device B to obtain modified powder 12. Furthermore, the modified powder 12, surfactant 1, and water were mixed to obtain a liquid composition 2 containing modified powder 12 (50 parts by mass), surfactant 1 (2.5 parts by mass), and water (47.5 parts by mass). [Example 3] F particles 1 and ceramic balls were placed in the pot of the stirring device C, and the pot was rotated to mix. Surfactant 1 and water were then placed in the pot and mixed to obtain a liquid composition 3 containing F particles 1 (50 parts by mass), surfactant 1 (2.5 parts by mass), and water (47.5 parts by mass). [Example 4] Modified powder 21 was obtained in the same manner as in Example 1 except that F particle 1 was changed to particle 2, and liquid composition 4 was obtained therefrom. [Example 5] Liquid composition 5 was obtained in the same manner as in Example 3, except that F particles 1 were changed to F particles 2.

[0073] 4. Evaluation 4-1. Evaluation of modified powder The average particle size, specific surface area, and tap density were measured for the modified powders or F particles obtained in Examples 1 to 5. The results are shown in Table 1. The tap density was measured using a measuring device such as Seishin Enterprise's "Tap Denser KYT-4000" by filling a 50 ml cup equipped with an auxiliary cup with 5 to 15 g of sample and tapping it 300 times, then removing the auxiliary cup and accurately reading the scale on the filled surface of the measurement sample, and calculating it using the following formula. Tap density (g / ml) = sample mass (g) / reading scale (ml)

[0074] 4-2. Evaluation of liquid compositions Each liquid composition (18 mL) was placed in a screw tube (internal volume: 30 mL) and allowed to stand at 25° C. for 7 days. Thereafter, the liquid composition in the screw tube was visually observed, and the dispersion stability was evaluated according to the following criteria. [Evaluation criteria] ◯: No aggregates are visible. △: Settling of aggregates is visible at the bottom of the container. Stirring with shearing force redisperses the material evenly. ×: Settling of aggregates is visible at the bottom of the container. Redispersion is difficult even when stirring with shear. The evaluation results are summarized in Table 1.

[0075] [Table 1] [Industrial Applicability]

[0076] The modified powder produced by the method of the present invention is excellent in dispersion stability, uniformity and ease of handling. From such modified powders, liquid compositions with excellent dispersion stability can be produced. Such liquid compositions can be formed into molded articles with excellent physical properties such as electrical properties, and can be easily processed into films, fiber-reinforced films, prepregs, metal laminates (resin-coated metal foils), etc. The resulting processed articles can be used as materials for antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, sliding bearings, etc.

Claims

1. A method for producing a modified powder, comprising stirring a powder consisting of particles of a heat-fusible tetrafluoroethylene-based polymer having an average particle size of 20 μm or less in a stirring device having rotation and revolution functions, to obtain a modified powder consisting of particles of a heat-fusible tetrafluoroethylene-based polymer having an average particle size of 20 μm or less and a specific surface area of ​​8 m2 / g or less, and having a tap density of 0.3 g / ml or more.

2. The method according to claim 1, wherein the melting temperature of the tetrafluoroethylene-based polymer is 200°C or higher and 320°C or lower.

3. The method according to claim 1 or 2, wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having an oxygen-containing polar group containing a unit based on perfluoro(alkyl vinyl ether).

4. The manufacturing method according to any one of claims 1 to 3, wherein the stirring device is any one of the stirring devices 1) to 6) below. 1) Agitation device equipped with a stirring tank equipped with a rotational and revolutional stirring mechanism 2) A stirring device equipped with a conical vessel that narrows downward and a spiral blade that rotates and revolves within the conical vessel. 3) Agitation device with multiple agitating blades that perform planetary motion 4) A flow-type agitator having an agitator blade with a drive shaft that penetrates vertically through the center of the bottom of the agitator tank. 5) A stirring device having a conical inner wall surface and a stirring blade with a drive shaft that penetrates vertically through the center of the tank bottom. 6) A cylindrical agitator having a cylindrical container that can rotate around a central axis as a rotation axis, and having a plurality of ribbon screw-shaped outer blades that screw along the inner wall inside the cylindrical container, and a plurality of ribbon screw-shaped inner blades that are disposed inside the outer blades and screw in the opposite direction to the outer blades.

5. The manufacturing method according to any one of claims 1 to 4, wherein the stirring treatment is carried out by a stirring device having a stirring tank equipped with a stirring mechanism that rotates and revolves, or a flow-type stirring device having a stirring blade with a drive shaft that vertically penetrates the center of the bottom of the stirring tank.

6. The method according to claim 5 , wherein the stirring treatment is carried out in a stirring tank equipped with a stirring mechanism that rotates and revolves, under conditions where the revolution speed is more than 1 time the rotation speed.

7. 7. The production method according to claim 5 or 6, wherein the peripheral speed of the rotational speed or revolutional speed in the stirring tank equipped with the stirring mechanism by rotation and revolution, or the peripheral speed of stirring in the flow-type stirring device, is 1 m / s or more and 100 m / s or less.

8. The manufacturing method according to any one of claims 1 to 7, wherein the stirring treatment is carried out with a filling amount of the powder of 50% by volume or less of the capacity of the stirring device.

9. The method according to any one of claims 1 to 8, wherein the powder is formed by pulverizing granules of a heat-fusible tetrafluoroethylene-based polymer obtained by radical polymerization in a polymerization medium.

10. The specific surface area of ​​the powder is 8 m ２ / g or less, and the specific surface area of ​​the modified powder is 90% or less of the powder.

11. The manufacturing method according to any one of claims 1 to 10, wherein the tap density of the powder is 0.3 g / ml or more, and the tap density of the modified powder is 1.2 times or more of the powder.

12. The manufacturing method according to any one of claims 1 to 11, wherein the ratio of the average particle size of the modified powder to the average particle size of the powder is 0.95 or more.

13. A method for producing a liquid composition, comprising: stirring a powder consisting of particles of a heat-fusible tetrafluoroethylene-based polymer having an average particle size of 20 μm or less in a stirring device having rotation and revolution functions to obtain a modified powder; and mixing the modified powder with a liquid dispersion medium to obtain a liquid composition.

14. Average particle size is 20 μm or less, specific surface area is 8 m ２ The modified powder has a tap density of 0.3 g / ml or more and is composed of particles of a heat-fusible tetrafluoroethylene-based polymer having a melting temperature of 200 to 320°C, the polymer being a polymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), or a polymer containing units based on tetrafluoroethylene and units based on hexafluoropropylene, and having a tap density of 0.3 g / ml or more.

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