TW202035479A - Dry powder and method for producing dry powder - Google Patents

Abstract

To provide a dry powder which is a blend of different kinds of tetrafluoroethylene polymer powders and uses a powder of a tetrafluoroethylene polymer that has an oxygen-containing polar group, and wherein the physical properties of the respective polymers are highly exhibited. A dry powder according to the present invention contains a tetrafluoroethylene polymer and a fluoropolymer which has an oxygen-containing polar group and a unit that is based on tetrafluoroethylene. It is preferable that the fluoropolymer has a melting point of from 140 DEG C to 320 DEG C. It is also preferable that the fluoropolymer contains a unit that is based on a monomer having the oxygen-containing polar group.

Description

Dry powder and dry powder manufacturing method

The present invention relates to a specific dry powder and its manufacturing method.

Polytetrafluoroethylene (PTFE), tetrafluoroethylene and perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene and hexafluoropropylene copolymer (FEP) and other tetrafluoroethylene polymer powders It has excellent physical properties such as mold releasability, electrical properties, water and oil repellency, chemical resistance, weather resistance, and heat resistance, and is used in various industrial applications.

In addition, it is sometimes tried to blend powders of different types of tetrafluoroethylene-based polymers to prepare powders having the physical properties of each tetrafluoroethylene-based polymer. As the method, the following method is proposed: a method of dry blending powders of different types of tetrafluoroethylene polymers without oxygen-containing polar groups, and in the above method, the melting temperature of the above tetrafluoroethylene polymers is Crushing after heating (refer to Patent Document 1); method of freeze-drying the aqueous dispersion of the above-mentioned powder (refer to Patent Document 2); method of coaggregating the aqueous dispersion containing the above-mentioned powder (refer to Patent Documents 3 to 5) ; And a method of spray drying an aqueous dispersion containing the above-mentioned powder (see Patent Document 6). [Prior technical literature] [Patent literature]

[Patent Document 1] Japanese Patent Publication No. 05-093086 [Patent Document 2] Japanese Patent Publication No. 2009-523851 [Patent Document 3] International Publication No. 2012/086710 [Patent Document 4] International Publication No. 2012/ No. 086725 [Patent Document 5] International Publication No. 2013/157647 [Patent Document 6] Japanese Patent Publication No. 2010-533763

[The problem to be solved by the invention]

When blending powders of tetrafluoroethylene-based polymers with insufficient interaction between molecules, if the dry blending method described in the previous technical literature is used, the homogeneity of the obtained powder is low, and its molding processability or The problem of insufficient physical properties of molded products. If the mechanical stress at the time of blending is increased, the polymer will deteriorate and its operability will be easily reduced. Furthermore, in the heat treatment method, if the heat treatment conditions are not strictly controlled, especially the cooling after heating, there is also a problem that the polymer is easily degraded.

In addition, the inventors have the following insights regarding the type of polymer, its combination, and the state of the dispersion in the method using coaggregation, the method using freeze drying, or the method using spray drying described in the prior art documents ( Factors such as polymer concentration, powder state, etc.) will greatly affect the physical properties of the obtained powder. For example, it has been found that the powder obtained by the method of co-aggregation has improved formability, but has lower adhesion to the substrate.

On the other hand, the blending of powders of different types of tetrafluoroethylene-based polymer powders using tetrafluoroethylene-based polymer powders having oxygen-containing polar groups, and the physical properties of the blended powders are not known. The inventors of the present invention conducted research on the blending of powders of different types of tetrafluoroethylene-based polymers using powders of tetrafluoroethylene-based polymers with oxygen-containing polar groups, which were previously unknown. As a result, it is possible to obtain a powder that forms a molded product with excellent extrusion moldability, stretch moldability, and adhesion without impairing the physical properties of each polymer, and a powder with high adhesion suitable for electrostatic coating.

The object of the present invention is to provide a dry powder which is a blended powder of powders of different types of tetrafluoroethylene polymer powders with oxygen-containing polar group tetrafluoroethylene polymer powder, and each polymer The physical properties of things are highly manifested. [Technical means to solve the problem]

The present invention provides the following inventions. <1> A dry powder comprising a fluoropolymer having a tetrafluoroethylene-based unit and an oxygen-containing polar group, and a tetrafluoroethylene-based polymer. <2> The dry powder as in the above <1>, wherein the melting temperature of the fluoropolymer is 140-320°C. <3> The dry powder as in the above <1> or <2>, wherein the fluoropolymer includes a unit based on a monomer having the oxygen-containing polar group. <4> The dry powder of any one of the above <1> to <3>, wherein the oxygen-containing polar group is a hydroxyl group-containing group or a carbonyl group-containing group. <5> The dry powder of any one of the above <1> to <4>, wherein the above tetrafluoroethylene polymer is: polytetrafluoroethylene, copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) , Copolymer of tetrafluoroethylene and hexafluoropropylene, copolymer of tetrafluoroethylene and ethylene, or copolymer of tetrafluoroethylene and vinylidene fluoride. <6> The dry powder according to any one of the above <1> to <5>, wherein the above tetrafluoroethylene-based polymer is polytetrafluoroethylene. <7> The dry powder of any one of the above <1> to <6>, wherein the ratio of the content of the fluoropolymer to the content of the tetrafluoroethylene-based polymer is 0.4 or less. <8> A method for producing dry powder, which is the method for producing dry powder as described in any one of the above <1> to <7>, the production method is based on the first powder containing the above-mentioned fluoropolymer and the above-mentioned tetrafluoroethylene In a powder dispersion of the second powder of the ethylene-based polymer and water, the first powder and the second powder are coaggregated to obtain a wet powder, and the wet powder is dried to obtain the dry powder. <9> A method for producing dry powder, which is the method for producing dry powder as described in any one of the above <1> to <7>, the production method is to make the first powder containing the above fluoropolymer and the above tetrafluoro The second powder of the ethylene-based polymer and the powder dispersion of water are frozen, and the water is sublimated to remove them, thereby obtaining the above-mentioned dry powder. <10> A method for producing dry powders, which is the method for producing dry powders in any one of the above <1> to <7>, the production method is to make the first powder containing the fluoropolymer and the tetrafluoroethylene The second powder of the ethylene-based polymer and the powder dispersion of water are spray-dried to obtain the above-mentioned dry powder. <11> A method for producing dry powder, which is the method for producing dry powder as described in any one of the above <1> to <7>, the production method is to combine the first powder of the fluoropolymer with the tetrafluoroethylene The second powder of the polymer is mixed, heat-treated at a temperature exceeding 320°C to obtain a mixture, and the mixture is pulverized to obtain the above-mentioned dry powder. <12> The manufacturing method of any one of the above <8> to <11>, wherein the volume-based cumulative 50% particle size of the first powder is 0.01 to 75 μm, and the volume-based cumulative 50% particle size of the second powder The diameter is 0.01-100 μm. [Effects of the invention]

According to the present invention, a dry powder can be obtained. The dry powder includes a fluoroolefin polymer having an oxygen-containing polar group and a tetrafluoroethylene polymer, and can form a solid powder with excellent extrusion moldability and extensibility. Subsequent molded products.

"D50 of powder" is the cumulative 50% particle size based on volume, and the particle size distribution is measured by laser diffraction and scattering methods. The cumulative volume is calculated by taking the total volume of the particle cluster as 100%, and the cumulative volume is accumulated on the cumulative curve The particle size reaches the 50% point. "D90 of powder" is the cumulative 90% particle size based on volume, and the particle size distribution is measured by laser diffraction and scattering methods. The total volume of the particle cluster is 100% to calculate the cumulative curve, and the cumulative volume is accumulated on the cumulative curve The particle size reaches the 90% point. "Monomer-based unit" is the collective term for the atomic group directly formed by polymerization of 1 molecule of monomer and the atomic group obtained by chemical conversion of a part of the atomic group. In this specification, monomer-based units are simply referred to as "units". "Polymer melting temperature (melting point)" is the temperature corresponding to the maximum value of the melting peak of the polymer measured by differential scanning calorimetry (DSC). The "melt viscosity of polymer" is based on ASTM D1238, using a flow test method and a 2Φ-8L mold. The polymer sample (2 g) that has been heated for 5 minutes at the measurement temperature is maintained under a load of 0.7 MPa The value measured for temperature measurement. "Viscosity of powder dispersion" is the value measured using a B-type viscometer at room temperature (25°C) at a rotational speed of 30 rpm. Repeat the measurement 3 times and take the average of the 3 measurements. "Powder dispersion thixotropy ratio" is the value calculated by dividing the viscosity η ₁ measured at a rotation speed of 30 rpm by the viscosity η ₂ measured at a rotation speed of 60 rpm. The measurement of each viscosity was repeated 3 times, and the average value of the 3 measurements was taken. "Laminated body peel strength" is fixed and cut into a rectangular shape (length 100 mm, width 10 mm) from one end of the longitudinal direction of the laminated body 50 mm away from one end of the length at a tensile speed of 50 mm/min The maximum load (N/cm) applied when peeling the metal foil from the resin layer at an angle of 90° with respect to the laminate. The "unit" in the polymer can be an atomic group formed directly from a monomer by polymerization, or a specific method is used to process the polymer obtained by the polymerization reaction, and a part of the structure is converted. The monomer A-based unit contained in the polymer is also simply referred to as "monomer A unit".

The dry powder of the present invention includes a fluoropolymer having a tetrafluoroethylene (TFE)-based unit (TFE unit) and an oxygen-containing polar group (hereinafter also referred to as "F polymer"), and a tetrafluoroethylene-based polymer (hereinafter Also referred to as "TFE-based polymer"). Furthermore, the F polymer is a different polymer from the TFE polymer. The molded product formed from the dry powder of the present invention (including molded parts such as a polymer layer; the same applies hereinafter) has excellent extrusion moldability and extensibility, and exhibits strong adhesion.

The reason is not necessarily clear. In addition to the reason that the F polymer and the TFE-based polymer are both fluoropolymers containing TFE units and have high compatibility, the reason why the F polymer has an oxygen-containing polar group can be cited. That is, it is believed that the oxygen-containing polar group of the F polymer not only exhibits adhesion, but also promotes the interaction between the polymers, such as the formation of a matrix. As described above, since the homogeneity of each polymer in the dry powder is relatively high, the formation of the matrix is further promoted, and a state where each polymer chain is easily and uniformly entangled is formed. As a result, it is considered that a molded product which is excellent in extrusion moldability and elongation and exhibits strong adhesiveness is obtained.

The melting temperature of the F polymer is preferably 140 to 320°C, more preferably 200 to 320°C, and still more preferably 260 to 320°C. In this case, it is easy to further improve the adhesion and crack resistance of the molded product. The oxygen-containing polar group contained in the F polymer may be contained in a unit based on a monomer having an oxygen-containing polar group, may be contained in the end group of the polymer, or may be subjected to surface treatment (radiation treatment, electron beam treatment, electric Corona treatment, plasma treatment, etc.) are included in the polymer, preferably the former. In addition, the oxygen-containing polar group possessed by the F polymer may also be a base prepared by modifying a polymer having a group capable of forming an oxygen-containing polar group. The oxygen-containing polar group contained in the polymer terminal group can be obtained by adjusting the components (polymerization initiator, chain transfer agent, etc.) used when polymerizing the polymer.

The oxygen-containing polar group is an atomic group containing the polarity of an oxygen atom. However, the oxygen-containing polar group of the present invention does not contain the ester bond itself and the ether bond itself, but includes atomic groups containing these bonds as characteristic groups. The oxygen-containing polar group is preferably at least one group selected from the group consisting of a hydroxyl group, a carbonyl group, an acetal group and an oxycycloalkane group, and more preferably a hydroxyl group or a carbonyl group.

The hydroxyl-containing group is preferably -CF ₂ CH ₂ OH, -C(CF ₃ ) ₂ OH, or 1,2-diol group (-CH(OH)CH ₂ OH). The carbonyl-containing group is preferably >C(O), -CF ₂ C(O)OH, >CFC(O)OH, formamido (-C(O)NH ₂ etc.), acid anhydride residue (-C (O)OC(O)-), imine residues (-C(O)NHC(O)- etc.), dicarboxylic acid residues (-CH(C(O)OH)CH ₂ C(O) OH etc.), or carbonate group (-OC(O)O-). The oxcycloalkane group is preferably an epoxy group or an oxetanyl group.

The oxygen-containing polar group is not easy to damage the adhesiveness and crack resistance of the molded product obtained from the dry powder. It is particularly preferred that the cyclic acid anhydride residue is a cyclic group or a ring-opening group as a polar group, The cyclic imine residue, the cyclic carbonate group, the cyclic acetal group, the 1,2-dicarboxylic acid residue or the 1,2-diol group, and the cyclic acid anhydride residue is most preferred.

The F polymer is preferably a polymer comprising: TFE units; units based on hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE) or fluoroalkyl ethylene (FAE) (also noted below) "PAE unit"); and a unit based on a monomer having an oxygen-containing polar group (hereinafter also referred to as "polar unit"). Regarding the ratio of TFE units, in all units constituting the F polymer, it is preferably 50-99 mol%, and more preferably 90-99 mol%.

The PAE unit is preferably a PAVE-based unit (hereinafter also referred to as "PAVE unit") or an HFP-based unit (hereinafter also referred to as "HFP unit"), more preferably a PAVE unit. There may be more than two types of PAE units. Regarding the ratio of PAE units, among all units constituting the F polymer, it is preferably 0-10 mol%, more preferably 0.5-997 mol%. Regarding the ratio of polar units, it is preferably 0.01-3 mol% in all units constituting the F polymer.

As the PAVE, CF ₂ =CFOCF ₃ (PMVE, Perfluorinated Methyl Vinyl Ether, perfluoromethyl vinyl ether), CF ₂ =CFOCF ₂ CF ₃ , CF ₂ =CFOCF ₂ CF ₂ CF ₃ (PPVE, Perfluoro propyl vinyl ether) ether, perfluoro n-propyl vinyl ether), CF ₂ =CFOCF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ =CFO(CF ₂ ) ₈ F, preferably PMVE or PPVE. Examples of FAE include CH ₂ =CH(CF ₂ ) ₂ F (PFEE, Perfluoro ethyl ethylene, perfluoroethyl ethylene), CH ₂ =CH(CF ₂ ) ₃ F, CH ₂ =CH(CF ₂ ) ₄ F (PFBE, Perfluoro butyl ethylene, perfluorobutyl ethylene), CH ₂ =CF(CF ₂ ) ₃ H, CH ₂ =CF(CF ₂ ) ₄ H, preferably PFEE or PFBE.

The polar unit may be one type or two or more types. Specific examples of monomers having oxygen-containing polar groups include: itaconic acid anhydride, citraconic acid anhydride, 5-norene-2,3-dicarboxylic acid anhydride (another name: bicycloheptene dicarboxylic acid anhydride; also noted below It is "NAH"), maleic anhydride, and a preferred specific example thereof includes NAH.

In addition, the F polymer in this case may further include units other than TFE units, PAE units, and polar units (hereinafter also referred to as "other units"). The other units may be one type or two or more types. Examples of monomers forming other units include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride (VDF), and chlorotrifluoroethylene (CTFE). The other unit is preferably ethylene, VDF or CTFE, more preferably ethylene. Regarding the ratio of other units in the F polymer, in all the units constituting the F polymer, it is preferably 0-50 mol%, more preferably 0-40 mol%.

The dry powder of the present invention may also contain various additives. Examples of additives include ultraviolet absorbers, light stabilizers, matting agents, leveling agents, surface regulators, surfactants, deaerators, plasticizers, fillers, heat stabilizers, tackifiers, dispersants, Rust inhibitor, silane coupling agent, antifouling agent, antifouling agent, flame retardant, etc.

The TFE-based polymer is preferably polytetrafluoroethylene (PTFE), a copolymer of TFE and PAVE (PFA), a copolymer of TFE and HFP (FEP), a copolymer of TFE and ethylene (ETFE), or a combination of TFE and VDF Copolymer, more preferably PTFE. Furthermore, in PTFE, in addition to the homopolymer of TFE, it also contains a very small amount of comonomer (PAVE, HFP, FAE, etc.) and the copolymer of TFE, so-called modified PTFE. In addition, PFA may also contain units based on monomers other than TFE and PAVE. The same applies to the other copolymers mentioned above. As mentioned above, the molded product not only exhibits strong adhesion and crack resistance, but also the physical properties of TFE-based polymers are not easily damaged. For example, when the TFE-based polymer is PTFE, the fibrous surface properties or porosity inherent in the PTFE molded product of the above-mentioned molded product are not easily damaged.

PTFE is preferably non-thermally fusible PTFE. As mentioned above, the dry powder of the present invention not only exhibits strong adhesion, but also the physical properties of the TFE-based polymer are not easily damaged. For example, when the TFE-based polymer is non-hot-melt PTFE, the original heat resistance of the non-hot-melt PTFE powder blended with the powder is not easily damaged. Regarding the ratio of TFE units in non-hot-melt PTFE, in all units, it is preferably 99.5 mol% or more, and more preferably 99.9 mol% or more.

The non-thermally fusible PTFE preferably has fibrous properties. As long as it has fibrous properties, the surface smoothness, mechanical properties (abrasion resistance, etc.), and weather resistance of the coating film obtained by electrostatic coating and calcination of the dry powder of the present invention are easily improved. Furthermore, the so-called fibrous non-hot-melt PTFE refers to PTFE that can be extruded from uncalcined polymer powder. That is, it means PTFE whose molded product obtained by paste extrusion has strength or ductility.

The number average molecular weight of non-hot-melt PTFE is preferably 300,000 to 300 million, more preferably 500,000 to 25 million. The standard specific gravity, which is an index of the average molecular weight of the non-hot-melt PTFE, is preferably 2.14-2.22, more preferably 2.15-2.21. The melt viscosity of non-hot-melt PTFE at 380°C is preferably 1×10 ⁹ Pa·s or more. The upper limit of the melt viscosity is usually 1×10 ¹⁰ Pa·s. As long as at least one of the number average molecular weight, standard specific gravity, and melt viscosity of the non-hot-melt PTFE is within the above range, the non-hot-melt PTFE has better fibrous properties and can form a molded product with more excellent mechanical properties.

The TFE-based polymer is preferably a polymer obtained by emulsion polymerization of a fluoroolefin in water. For example, PTFE is preferably a polymer obtained by emulsion polymerization of TFE in water. The first powder of PTFE is a powder in which a polymer obtained by emulsion polymerization of TFE in water is dispersed in water in the form of particles. When using the powder, the powder dispersed in water can be used directly, or the powder can be recovered from water for use.

TFE-based polymers can be modified by surface treatment (radiation treatment, electron beam treatment, corona treatment, plasma treatment, etc.). As the method of this surface treatment, the methods described in International Publication No. 2018/026012, International Publication No. 2018/026017, etc. can be cited. Regarding TFE-based polymers, powders or dispersions are widely available in the form of commercially available products.

The ratio of the mass of the F polymer to the mass of the TFE-based polymer (the content of the F polymer/the content of the TFE-based polymer) in the dry powder of the present invention is preferably 0.4 or less, more preferably 0.15 or less. In this case, the interaction between the dry powders becomes good, and it is easy to obtain a dry powder with particularly excellent extrusion moldability and stretch moldability. The lower limit of the above mass ratio is usually 0.01.

As a preferable aspect of the dry powder of the present invention, there can be mentioned: in a powder dispersion containing a first powder of F polymer, a second powder of TFE-based polymer, and water, the first powder and the second The dry powder obtained by coaggregating the powder and then drying (hereinafter also referred to as "the first dry powder"); freezing the powder dispersion of the first powder containing F polymer, the second powder of TFE-based polymer, and water , A dry powder obtained by sublimating water to remove it (hereinafter also referred to as "the second dry powder"); a powder dispersion containing the first powder of F polymer, the second powder of TFE-based polymer, and water Dry powder obtained by spray drying (hereinafter also referred to as "third dry powder"); mix the first powder of F polymer and the second powder of TFE-based polymer, and heat-treat at a temperature exceeding 320°C to obtain the mixture , The dry powder obtained by pulverizing the mixture (hereinafter also referred to as "the fourth dry powder").

The first dry powder can be described as a powder in which F polymer and TFE-based polymer are uniformly mixed. It does not depend on the blending ratio of each polymer. The reason is not necessarily clear. In addition to the reason that the F polymer and the TFE-based polymer are both fluoropolymers containing TFE units and have high compatibility, the reason why the F polymer has an oxygen-containing polar group can also be cited. That is, it is believed that the F polymer has high stability in an aqueous medium due to the oxygen-containing polar group and also interacts with the TFE-based polymer, so that the powders are in a uniformly dispersed state. If the powder dispersion in this good dispersed state is subjected to the co-aggregation treatment, it is considered that the co-aggregation of the first powder and the second powder proceeds by involving the powders. As a result, it is considered that a homogeneous powder is obtained. The D50 of the first dry powder is preferably 100-1000 μm, more preferably 300-800 μm. The apparent density of the first dry powder is preferably 0.40 to 0.60 g/mL, more preferably 0.45 to 0.55 g/mL. The apparent density is a value measured in accordance with JIS K6892.

The first dry powder is preferably obtained by the following first method. The extrusion moldability and stretch moldability of the first dry powder are particularly excellent, and the obtained molded product exhibits strong adhesion. The first powder is extruded to obtain a sheet, and a stretched sheet can be obtained by subjecting the sheet to a stretching process. As the extension condition, an extension ratio of 200% or more can be used at a speed of 5 to 1000%/sec. Moreover, as long as the first dry powder is extruded, the coating material can also be obtained. In the former first dry powder extrusion molding, as long as the TFE-based polymer is fibrous high-molecular-weight PTFE, a porous stretched film can also be manufactured.

A known method can be used for each extrusion molding method. For example, the method of extrusion molding when the first dry powder is formed into a sheet is preferably a method in which extruded beads obtained by extruding the paste from fine powder into a sheet shape by calendering or the like. The first dry powder in this case may also contain lubricants represented by petroleum hydrocarbons such as naphtha. Regarding the mixing ratio of the lubricant, the lubricant is usually 15-30 parts by mass relative to 100 parts by mass of the fine powder.

The second dry powder can be described as a dry powder with high homogeneity including F polymer and TFE-based polymer. It does not depend on the blending ratio of each polymer. The second dry powder is a powder that has the physical properties of the original TFE-based polymer and is suitable for electrostatic coating. The reason is not necessarily clear. In addition to the reason that the F polymer and the TFE-based polymer are both fluoropolymers containing TFE units and have high compatibility, the reason why the F polymer has an oxygen-containing polar group can also be cited. That is, it is believed that the oxygen-containing polar group of the F polymer not only exhibits adhesion, but also balances the electrostatic properties of the entire dry powder, and promotes the interaction between the polymers, such as the formation of a matrix. As described above, it is believed that the dry powder has high homogeneity, and therefore further promotes the formation of the matrix, and forms a state where each polymer chain is easily and uniformly entangled. As a result, it is considered that the physical properties of the original TFE-based polymer are not damaged, and good electrostatic coating properties and excellent adhesiveness can be exhibited.

The second dry powder can also be used for various subsequent processing depending on its purpose. Examples of this post-treatment include pulverization treatment using a pin mill or jet mill, radiation treatment, corona treatment, electron beam treatment, and plasma treatment. The D50 of the second dry powder is preferably 0.01 to 75 μm, more preferably 0.05 to 6 μm, and still more preferably 0.1 to 4 μm. The D90 of the second dry powder is preferably 8 μm or less, more preferably 6 μm or less.

The second dry powder is a powder with higher uniformity of F polymer and TFE polymer. It is easy to maintain the potential of the powder surface to be neutral, and it is easy to further reduce the angle of repose. The angle of repose of the second dry powder is preferably 50° or less, more preferably 35° or less. In addition, the lower limit of the angle of repose is not particularly limited, but is usually 5°. In this case, the supply of dry powder to the coating device during electrostatic coating becomes smooth, and the coating film has excellent surface smoothness, thickness uniformity, and processability. Furthermore, the angle of repose is determined by measuring the dried dry powder in accordance with "JIS R 9301-2-2 Alumina Powder-Part 2: Measuring Methods of Physical Properties-2: Angle of Repose".

As long as the second dry powder is electrostatically coated on the surface of the substrate, and the substrate is heated to form a calcined product of the second dry powder, a laminated body (coating Loaded items). The coated article has a substrate and a calcined product as a coating film formed from the second dry powder on the substrate, and has excellent adhesion, surface smoothness, thickness uniformity, and processability.

The material of the substrate is not particularly limited, and examples thereof include inorganic materials, organic materials, and organic-inorganic composite materials. Examples of inorganic substances include concrete, natural stone, glass, and metals (iron, stainless steel, aluminum, copper, brass, titanium, etc.). Examples of organic substances include plastic, rubber, adhesives, and wood. Examples of organic-inorganic composite materials include fiber reinforced plastics, resin reinforced concrete, and fiber reinforced concrete. In addition, the base material may be subjected to well-known surface treatment (chemical treatment, etc.). The material of the substrate is preferably metal, more preferably aluminum or copper.

The thickness of the coating film of the coated article can be appropriately set according to the purpose of the coated article, and is preferably 1 to 1000 μm, more preferably 20 to 300 μm. The painted articles include: roofs, aluminum composite panels, aluminum panels for curtain walls, aluminum frames for curtain walls, aluminum window frames and other building exterior components; road materials such as signals, telephone poles, road marking poles, and guard rails; Automobile body or parts (bumper, wiper blade, wheel tyre, etc.); household appliances (outdoor unit of air conditioner, water heater, etc.); blades for wind power generation, solar cell bottom sheet, heat collection for solar thermal power generation The reverse side of the mirror, sodium-sulfur battery exterior, generator.

When manufacturing coated articles, electrostatic coating and heating of the second dry powder can be performed simultaneously, or the substrate can be heated after the second dry powder is electrostatically coated on the surface of the substrate. The heating temperature of the second dry powder after electrostatic coating is usually 260～380℃. The time to maintain the heating temperature is usually 1 to 60 minutes. As a method for electrostatic coating of the second dry powder, the following electrostatic coating method is preferable: the dry powder is supplied from the tank to the coating gun, and the second dry powder is sprayed (injected) from the coating gun toward the surface of the substrate. The spray volume of the second dry powder (powder coating) from the coating gun can be set to 50～200 g/min.

Regarding the distance from the tip of the coating gun (ie, the nozzle of the second dry powder) to the surface of the substrate, from the viewpoint of coating efficiency, it is preferably 150-400 mm. When the electrostatic coating method is implemented industrially, it is better to install a grounded conductive horizontal belt conveyor in the painting room, and install the painting gun vertically above the horizontal belt conveyor in the painting room . The width of the coating pattern is preferably 50-500 mm, the running speed of the coating gun is preferably 1-30 m/min, and the conveying speed is preferably 1-50 m/min. After applying the second dry powder electrostatically to the surface of the substrate, heating the substrate to form a coating film, and then cooling the coated article to room temperature (20-25°C). For cooling, either rapid cooling or slow cooling can be used. From the viewpoint of suppressing peeling of the coating film from the substrate, slow cooling is preferred.

The third dry powder can be described as a powder in which F polymer and TFE-based polymer are uniformly mixed. It does not depend on the blending ratio of each polymer. The reason is not necessarily clear. As mentioned above, it is considered that the water dispersion in a state where the powders are uniformly dispersed is subjected to spray drying (spray drying), and the water volatilizes to form a homogenous first powder and second powder.的粉。 The powder.

The D50 of the third dry powder is preferably 1-100 μm, more preferably 3-50 μm. The third dry powder is also the same as the first dry powder or the second dry powder. As long as it is used for extrusion molding and stretch molding, it can be processed into a stretched sheet or porous stretched film with excellent adhesion. Moreover, as long as it is applied to electrostatic coating, it is possible to form a coated article with excellent adhesion, surface smoothness, thickness uniformity, and processability.

The fourth dry powder also contains TFE-based polymer and F polymer with high uniformity, and has excellent adhesion and fiber resistance. The reason may not be clear, but it is considered as follows. As long as the temperature of the heat treatment when obtaining the mixture exceeds 320°C, it will easily exceed the melting temperature of the F polymer and easily become near the melting temperature of the TFE-based polymer. Therefore, the TFE-based polymer becomes a gelled (softened) state during the heat treatment, and the F polymer becomes a highly molten state, so the two are in a state of easy adhesion or fusion. At this time, it is considered that the interaction between the F polymer having an oxygen-containing polar group and the TFE-based polymer is increased, and a matrix is formed in the mixture to inhibit the crystallization of the TFE-based polymer. In addition, since the mixture was pulverized to obtain the fourth dry powder, it is considered that a powder with high uniformity between the TFE-based polymer and the F polymer was obtained.

Therefore, it is inferred that the fourth dry powder exhibits higher adhesion and higher fiber resistance due to the action of the F polymer with oxygen-containing polar groups. This tendency becomes obvious when the TFE-based polymer is PTFE whose melting temperature exceeds 320°C and the melting temperature of the F polymer is 260-320°C. That is, the TFE-based polymer in the fourth dry powder is preferably PTFE whose melting temperature exceeds 320°C, and is preferably the aforementioned non-melting PTFE. In addition, the melting temperature of the F polymer in the fourth dry powder is preferably 260 to 320°C. Furthermore, in the fourth dry powder, since the original physical properties (heat resistance, etc.) of the TFE-based polymer are well maintained, it can be suitably used as a powder coating for electrostatic coating, for example. Specifically, the fourth dry powder is the same as the second dry powder. As long as it is applied to electrostatic coating, a coated article with excellent adhesion, surface smoothness, thickness uniformity, and workability can be formed.

The melt viscosity of the F polymer in the fourth dry powder at 380°C is preferably 1×10 ² to 1×10 ⁶ Pa·s, more preferably 5×10 ² to 5×10 ⁵ Pa·s. In this case, since the fluidity of the F polymer is further improved, the adhesion of the F polymer to the TFE-based polymer can be further improved. The ratio of the mass of the TFE polymer in the fourth dry powder to the mass of the F polymer (the content of TFE polymer/the content of F polymer) is preferably 5 or more, more preferably 5-50, and more Preferably, it is 10-25. In this case, the interaction between the powders becomes good, and in the fourth dry powder, the TFE-based polymer and the F polymer are likely to exist more uniformly. Therefore, it is easy to obtain a powder with particularly excellent adhesion without damaging the physical properties of the TFE-based polymer.

The fourth dry powder is a powder containing PTFE and F polymer. The fourth dry powder can also be used for various subsequent processing depending on its purpose. Examples of this post-treatment include radiation treatment, corona treatment, electron beam treatment, and plasma treatment. The D50 of the fourth dry powder is preferably 0.1-50 μm, more preferably 0.3-40 μm, and still more preferably 1-30 μm. The D90 of the fourth dry powder is preferably 80 μm or less, more preferably 65 μm or less, and still more preferably 40 μm or less.

As a method of producing the first dry powder, a powder dispersion containing the first powder of the F polymer, the second powder of the TFE-based polymer, and water can be used to coaggregate the first powder and the second powder to obtain a wet powder. Powder, a method of drying the wet powder (hereinafter also referred to as "the first method"). The powder dispersion can also be referred to as a particle-like dispersion in which the first powder and the second powder are respectively dispersed in an aqueous medium containing water as the main component. The dry powder obtained by the first method can be said to be a fine powder obtained by co-aggregation of the first powder and the second powder and highly uniformly mixed with F polymer and TFE-based polymer. It does not depend on the blending ratio of each polymer.

The reason is not necessarily clear. In addition to the reason that the F polymer and the TFE-based polymer are both fluoropolymers containing TFE units and have high compatibility, the reason why the F polymer has an oxygen-containing polar group can be cited. That is, it is considered that the F polymer has high stability in an aqueous medium due to its oxygen-containing polar group and also interacts with the TFE-based polymer, so the powders are in a uniformly dispersed state. If the powder dispersion in this good dispersion state is subjected to the co-aggregation treatment, it is considered that the co-aggregation of the first powder and the second powder proceeds by involving the powders. As a result, it is considered that a homogeneous fine powder is obtained.

Regarding the oxygen-containing polar group contained in the F polymer in the first method and the respective ranges of the F polymer, including preferred ranges, they are the same as those in the dry powder of the present invention. The first powder in the first method may also contain components other than F polymer, but it is preferable to use F polymer as the main component. The content of the F polymer in the first powder is preferably 80% by mass or more, more preferably 100% by mass.

The D50 of the first powder is preferably 0.01 to 75 μm, more preferably 0.05 to 6 μm, and still more preferably 0.1 to 4 μm. The D90 of the first powder is preferably 8 μm or less, more preferably 6 μm or less. The range of the TFE-based polymer in the first method, including the preferred range, is the same as the range of the TFE-based polymer in the dry powder of the present invention.

The second powder is preferably a powder in which a polymer obtained by emulsion polymerization of a fluoroolefin in water is dispersed in water in the form of particles. When using the powder, the powder dispersed in water can be used directly, or the powder can be recovered from water for use. The second powder in the first method may also contain components other than the TFE-based polymer, but it is preferable to use the TFE-based polymer as the main component. The content of the TFE-based polymer in the second powder is preferably 80% by mass or more, more preferably 100% by mass. In addition, in this specification, when the second powder contains components (surfactants, etc.) used in the production of the TFE-based polymer, the components are not included in components other than the TFE-based polymer.

The D50 of the second powder is preferably 0.01-100 μm, more preferably 0.1-10 μm. The D90 of the second powder is preferably 200 μm or less, more preferably 20 μm or less. In this case, the interaction between the powders becomes good, and it is easy to further improve the co-aggregation of the first powder and the second powder and the physical properties of the molded product.

As a preferred aspect of the relationship between the D50 of the first powder and the D50 of the second powder in the first method, the D50 of the first powder is 0.1 μm or more and less than 1 μm, and the D50 of the second powder is 0.1 The aspect where the D50 of the first powder is 1 μm or more and 4 μm or less, and the aspect of the D50 of the second powder is 0.1 μm or more and 1 μm or less. In the former aspect, it is easy to obtain molded products with particularly excellent extrusion formability and stretch formability. In the latter aspect, it is easy to obtain molded products with excellent crack resistance.

The ratio of the mass of the F polymer to the mass of the TFE-based polymer (the content of the F polymer/the content of the TFE-based polymer) in the first method is preferably 0.4 or less, more preferably 0.15 or less. In this case, the interaction between the powders becomes good, and the co-aggregation of the first powder and the second powder is likely to be further improved. Therefore, it is possible to obtain a first dry powder having particularly excellent extrusion moldability and stretch moldability without impairing the physical properties of the TFE-based polymer, and it is easy to obtain a molded product having particularly excellent adhesiveness. The lower limit of the above mass ratio is usually 0.01. The total ratio of the F polymer to the TFE-based polymer in the powder dispersion of the first method is preferably 20 to 70% by mass, more preferably 30 to 60% by mass.

The powder dispersion in the first method preferably contains a dispersant from the viewpoint of enhancing the dispersibility of each powder and improving the co-coagulability of the powder. Furthermore, components used in the production of polymers (for example, surfactants used in emulsification and polymerization of fluoroolefins) do not belong to the dispersants in the first method. The dispersant is preferably a compound having a hydrophobic site and a hydrophilic site, and examples include acetylene-based surfactants, silicone-based surfactants, and fluorine-based surfactants. These dispersants are preferably nonionic. The dispersant is preferably a fluoroalcohol, more preferably a fluoromonohydric alcohol or a fluoropolyhydric alcohol.

The fluorine content of the fluorine monohydric alcohol is preferably from 10 to 50% by mass, more preferably from 10 to 45% by mass, and still more preferably from 15 to 40% by mass. The fluoromonohydric alcohol is preferably non-ionic. The hydroxyl value of the fluoromonohydric alcohol is preferably 40-100 mgKOH/g, more preferably 50-100 mgKOH/g, and still more preferably 60-100 mgKOH/g.

The fluorine monohydric alcohol is preferably a compound represented by the following formula (a). Of formula ^{(a): R a - (} OQ a) ma -OH wherein the symbol is the following meanings. R ^a represents a polyfluoroalkyl group containing an ether oxygen atoms or a polyfluoroalkyl group, preferably a _{-CH 2 (CF 2) 4 F} , -CH 2 (CF 2) 6 F, -CH 2 CH 2 (CF 2 ) ₄ F, -CH ₂ CH ₂ (CF ₂ ) ₆ F, -CH ₂ CF ₂ OCF ₂ CF ₂ OCF ₂ CF ₃ , -CH ₂ CF (CF ₃ )CF ₂ OCF ₂ CF ₂ CF ₃ , -CH ₂ CF(CF ₃ )OCF ₂ CF(CF ₃ )OCF ₃ , or -CH ₂ CF ₂ CHFO(CF ₂ ) ₃ OCF ₃ . Q ^a represents an alkylene group having 1 to 4 carbon atoms, preferably an ethylene group (-CH ₂ CH ₂ -) or a propylene group (-CH ₂ CH(CH ₃ )-). Q ^a may include two or more groups. When two or more types of groups are included, the arrangement of the groups may be random or block. ma represents an integer of 0-20, preferably an integer of 4-10. The hydroxyl group of the fluoromonohydric alcohol is preferably a secondary hydroxyl group or a tertiary hydroxyl group, and more preferably a secondary hydroxyl group.

Specific examples of fluorine monohydric alcohols include: F(CF ₂ ) ₆ CH ₂ (OCH ₂ CH ₂ ) ₇ OCH ₂ CH(CH ₃ )OH, F(CF ₂ ) ₆ CH ₂ (OCH ₂ CH ₂ ) ₁₂ OCH ₂ CH(CH ₃ )OH, F(CF ₂ ) ₆ CH ₂ CH ₂ (OCH ₂ CH ₂ ) ₇ OCH ₂ CH(CH ₃ )OH, F(CF ₂ ) ₆ CH ₂ CH ₂ (OCH ₂ CH ₂ ) ₁₂ OCH ₂ CH(CH ₃ )OH, F(CF ₂ ) ₄ CH ₂ CH ₂ (OCH ₂ CH ₂ ) ₇ OCH ₂ CH(CH ₃ )OH. The fluoromonohydric alcohol is commercially available ("Fluowet N083", "Fluowet N050", etc. manufactured by Archroma Corporation).

The fluorine content of the fluorine polyol is preferably from 10 to 50% by mass, more preferably from 10 to 45% by mass, and still more preferably from 15 to 40% by mass. The fluorine polyol is preferably non-ionic. The hydroxyl value of the fluoropolyol is preferably 10 to 35 mgKOH/g, more preferably 10 to 30 mgKOH/g, and still more preferably 10 to 25 mgKOH/g. The weight average molecular weight of the fluoropolyol is preferably 2,000 to 80,000, more preferably 6,000 to 20,000. The fluorine polyol is preferably a fluorine polyol containing units based on fluorine (meth)acrylate. Furthermore, the so-called "(meth)acrylate" is a general term for acrylate and methacrylate.

The fluorine (meth)acrylate is preferably a monomer represented by the following formula (f). Formula (f): CH ₂ =CX ^f C(O)OQ ^f -R ^f The symbols in the formula indicate the following meanings. X ^f represents a hydrogen atom, a chlorine atom or a methyl group. Q ^f represents an alkylene group having 1 to 4 carbons or an oxyalkylene group having 2 to 4 carbons. R ^f represents a polyfluoroalkyl group with 1 to 6 carbons, a polyfluoroalkyl group with 3 to 6 carbons containing an etheric oxygen atom, or a polyfluoroalkenyl group with 4 to 12 carbons, preferably -CF(CF ₃ )(C(CF(CF ₃ ) ₂ )(=C(CF ₃ ) ₂ )), -C(CF ₃ )=C(CF(CF ₃ ) ₂ ) ₂ , -(CF ₂ ) ₄ F or -( CF ₂ ) ₆ F.

Specific examples of fluorine (meth)acrylates include CH ₂ =CHC(O)OCH ₂ CH ₂ (CF ₂ ) ₄ F, CH ₂ =C(CH ₃ )C(O)OCH ₂ CH ₂ (CF ₂ ) ₄ F、CH ₂ =CHC(O)OCH ₂ CH ₂ (CF ₂ ) ₆ F、CH ₂ =C(CH ₃ )C(O)OCH ₂ CH ₂ (CF ₂ ) ₆ F、CH ₂ =CHC (O)OCH ₂ CH ₂ OCF(CF ₃ )(C(CF(CF ₃ ) ₂ )(=C(CF ₃ ) ₂ )), CH ₂ =C(CH ₃ )C(O)OCH ₂ CH ₂ OC (CF ₃ )=C(CF(CF ₃ ) ₂ ) ₂ 、CH ₂ =CHC(O)OCH ₂ CH ₂ CH ₂ CH ₂ OCF(CF ₃ )(C(CF(CF ₃ ) ₂ )(=C( CF ₃ ) ₂ )), CH ₂ =C(CH ₃ )C(O)OCH ₂ CH ₂ CH ₂ CH ₂ OC(CF ₃ )=C(CF(CF ₃ ) ₂ ) ₂ .

As a preferred specific example of the fluorine polyol, a copolymer of a monomer represented by the above formula (f) and a monomer represented by the following formula (o) can be cited. Formula (o): CH ₂ =CX ^o C(O)-(OZ ^o ) _mo -OH The symbols in the formula indicate the following meanings. X ^o represents a hydrogen atom or a methyl group. Z ^o represents an alkylene group having 1 to 4 carbon atoms, preferably an ethylene group (-CH ₂ CH ₂ -). mo is an integer of 1 to 200, preferably an integer of 4 to 30. Furthermore, Z ^o may include two or more groups. In this case, the arrangement of different types of alkylene groups can be random or block.

As specific examples of the monomer represented by formula (o), CH ₂ =CHCOO(CH ₂ CH ₂ O) ₈ OH, CH ₂ =CHCOO(CH ₂ CH ₂ O) ₁₀ OH, CH ₂ =CHCOO(CH ₂ CH ₂ O) ₁₂ OH, CH ₂ =CHCOOCH ₂ CH ₂ CH ₂ CH ₂ O(CH ₂ CH ₂ O) ₈ OH, CH ₂ =CHCOOCH ₂ CH ₂ CH ₂ CH ₂ O(CH ₂ CH ₂ O) ₁₀ OH, CH ₂ =CHCOOCH ₂ CH ₂ CH ₂ CH ₂ O(CH ₂ CH ₂ O) ₁₂ OH, CH ₂ =C(CH ₃ )COO(CH ₂ CH(CH ₃ )O) ₈ OH, CH ₂ =C (CH ₃ )COO(CH ₂ CH(CH ₃ )O) ₁₂ OH、CH ₂ =C(CH ₃ )COO(CH ₂ CH(CH ₃ )O) ₁₆ OH、CH ₂ =C(CH ₃ )COOCH ₂ CH ₂ CH ₂ CH ₂ O(CH ₂ CH(CH ₃ )O) ₈ OH, CH ₂ =C(CH ₃ )COOCH ₂ CH ₂ CH ₂ CH ₂ O(CH ₂ CH(CH ₃ )O) ₁₂ OH, CH ₂ =C(CH ₃ )COOCH ₂ CH ₂ CH ₂ CH ₂ O(CH ₂ CH(CH ₃ )O) ₁₆ OH.

The above-mentioned fluorine polyol may include only the unit based on the monomer represented by formula (f) and the unit based on the monomer represented by formula (o), and may further include other units. The content of the unit based on the monomer represented by the formula (f) relative to all the units contained in the fluoropolyol is preferably 60-90 mol%, more preferably 70-90 mol%. The content of the unit based on the monomer represented by formula (o) relative to all the units contained in the fluoropolyol is preferably 10-40 mol%, more preferably 10-30 mol%. The total content of the unit based on the monomer represented by formula (f) and the monomer represented by formula (o) relative to all the units contained in the fluorine polyol is preferably 90-100 mol%, more preferably 100 mol%. The ratio of fluoroalcohol in the powder dispersion is preferably 10% by mass or less, more preferably 1% by mass or less, and still more preferably 0.01% by mass or less. The lower limit of the above ratio usually exceeds 0%.

The powder dispersion in the first method contains an aqueous medium (dispersion medium of the powder dispersion) containing water as a main component. The aqueous medium may only contain water, or may contain water and water-soluble compounds. However, the water-soluble compound is preferably a compound that is liquid at 25°C, does not react with F polymer and TFE-based polymer, and can be easily removed by heating or the like. Furthermore, the ratio of water in the aqueous medium is preferably 95% by mass or more, more preferably 99% by mass or more, and still more preferably 100% by mass. The ratio of the aqueous medium in the powder dispersion is preferably 15 to 65% by mass, more preferably 25 to 50% by mass. Within this range, the co-aggregability of the powder dispersion is particularly excellent.

As a method of co-aggregation in the first method, the following method can be cited: stirring the powder dispersion liquid whose polymer content has been adjusted to co-aggregate the dispersed first powder and second powder. At this time, the content of the polymer is preferably 8-25% by mass. In order to achieve this content, it is only necessary to dilute the powder dispersion with water as necessary. The temperature during co-aggregation is preferably 5-30°C. Coagulate and adjust the pH value of the powder dispersion as needed. In addition, a pH adjuster, electrolyte, organic solvent, and agglutination aid may be added to the powder dispersion liquid.

Examples of the pH adjuster include sodium carbonate, sodium bicarbonate, ammonia, ammonium salts, and urea. As the electrolyte, inorganic salts such as potassium nitrate, sodium nitrate, sodium carbonate, and sodium bicarbonate can be cited. Examples of organic solvents include alcohol and acetone. Examples of the agglutination aid include nitric acid, hydrochloric acid, sulfuric acid, magnesium chloride, calcium chloride, sodium chloride, aluminum sulfate, magnesium sulfate, and barium sulfate.

In the first method, the first powder and the second powder are coaggregated by stirring the powder dispersion, and if the condensed powder is separated from the aqueous medium, a wet powder can be obtained. At this time, it is preferable to adjust the particle size by a granulation step or a granulation step. The so-called granulation step is the step of granulating the D50 of the condensate powder to 100-1000 μm, and the so-called granulation step is the step of adjusting the particle properties and particle size distribution of the condensate powder by stirring. With this, fine powder (condensed powder) in a wet state, that is, wet powder, can be obtained.

Furthermore, the powder dispersion for co-aggregation can be prepared by the following method: a method of mixing a dispersion containing the first powder and water with a dispersion containing the second powder and water; A method of mixing a water dispersion with the second powder; a method of mixing a dispersion containing the second powder and water with the first powder. However, from the viewpoint of easily dispersing each component uniformly, the powder dispersion is preferably prepared by the former method.

Then, if the obtained wet powder is dried, the first dry powder is obtained. The drying temperature is preferably 110 to 250°C, more preferably 120 to 230°C. In this case, the productivity and extrusion molding properties of the first dry powder are easily balanced.

As a second method of producing dry powder, the following method can be cited: a powder dispersion containing a first powder of F polymer, a second powder of a TFE-based polymer, and water is frozen, and the self-freezing powder dispersion sublimates water to Remove it (hereinafter also referred to as "Method 2"). The dispersion can also be referred to as a dispersion in which the first powder and the second powder are dispersed in the form of particles in water. The second dry powder obtained by the second method can be described as a self-frozen powder dispersion liquid obtained by sublimation to remove water and a dry powder containing F polymer and TFE-based polymer with high homogeneity. It does not depend on the blending ratio of each polymer.

The reason is not necessarily clear. As described above, it is considered that if the powder dispersion in a state where the respective powders are uniformly dispersed is frozen, a frozen product in which the first powder and the second powder are taken in as they are can be obtained. Since water was sublimed from the frozen material to remove it, it is considered that a homogeneous dry powder containing F polymer and TFE-based polymer was obtained.

Regarding the oxygen-containing polar group contained in the F polymer in the second method and the respective ranges of the F polymer, including the preferred ranges, they are the same as those in the dry powder of the present invention. Regarding the range of the first powder in the second method, the range including the preferred range is the same as the range of the first powder in the first method. The range of the TFE-based polymer in the second method, including the preferred range, is the same as the range of the TFE-based polymer in the dry powder of the present invention. Regarding the range of the first powder in the second method, the range including the preferred range is the same as the range of the first powder in the first method.

In addition, the preferred aspect of the relationship between the D50 of the first powder and the D50 of the second powder in the second method is the same as that in the first method. Regarding the range of the ratio of the mass of the F polymer to the mass of the TFE-based polymer in the second method (the content of the F polymer/the content of the TFE-based polymer), including the preferred range and the first method The range of the ratio of the mass of the F polymer to the mass of the TFE-based polymer is the same. Regarding the range of the powder dispersion in the second method, the range including the preferred range is the same as the range of the powder dispersion in the first method.

The freezing of the powder dispersion in the second method is preferably performed at a temperature lower than 0°C. Specifically, it is preferable to freeze the powder dispersion liquid by exposing it to an environment of -78 to -10°C. From the standpoint of suppressing precipitation of the components of the powder dispersion, freezing is preferably completed within 8 hours. In addition, from the viewpoint of suppressing the unevenness of the frozen product due to rapid freezing, it is preferable to freeze the powder dispersion liquid for 10 minutes or more. When the self-frozen powder dispersion (frozen material) removes water by sublimation, it should be carried out under the condition that the melting of the powder dispersion is suppressed. The temperature when the water is sublimated is preferably less than 0°C. Specifically, it is preferable to expose the frozen object to an environment of -78 to +0°C. In addition, the pressure when the water is sublimated is usually a reduced pressure environment, preferably a reduced pressure environment of 0 to 6.12×10 ² Pa. The time for sublimating water is usually 4 to 72 hours. Examples of devices used for sublimation include centrifugal separators and laminate dryers.

As the third method of producing dry powder, a method of spray drying a powder dispersion of the first powder containing F polymer, the second powder of TFE-based polymer, and water (hereinafter also referred to as "the third method") . The dispersion can also be referred to as a dispersion in which the first powder and the second powder are dispersed in the form of particles in water. The dry powder obtained by the third method can be described as a highly homogeneous blended powder containing F polymer and TFE-based polymer obtained by volatilizing and removing water from the powder dispersion by spray drying. It does not depend on the blending ratio of each polymer.

The reason is not necessarily clear. As described above, it is thought that the reason is that if the powder dispersion in the state where the powders are uniformly dispersed is spray-dried, water is volatilized and removed, and it is easy to directly form a homogeneous blended powder. The third method is preferably performed by spraying the powder dispersion in an environment exceeding 100°C. As a specific method, the following method is preferable: in a system in which an inert gas (preferably nitrogen gas) exceeding 100° C. is circulated vertically above, the powder dispersion liquid is sprayed vertically downward to dry the powder dispersion liquid. In this method, equipment such as a crystallization tower can be used.

Regarding the respective ranges of the oxygen-containing polar group contained in the F polymer and the F polymer in the third method, including the preferred ranges, they are the same as those in the dry powder of the present invention. Regarding the range of the first powder in the third method, including the preferred range, the range of the first powder in the first method is the same. The range of the TFE-based polymer in the third method, including the preferred range, is the same as the range of the TFE-based polymer in the dry powder of the present invention. Regarding the range of the first powder in the third method, including the preferable range, the range of the first powder in the first method is the same.

In addition, the preferred aspect of the relationship between the D50 of the first powder and the D50 of the second powder in the third method is the same as that in the first method. Regarding the range of the ratio of the mass of the F polymer to the mass of the TFE-based polymer in the third method (the content of the F polymer/the content of the TFE-based polymer), including the preferred range and the first method The range of the ratio of the mass of the F polymer to the mass of the TFE-based polymer is the same. Regarding the range of the powder dispersion in the third method, the range including the preferable range is the same as the range of the powder dispersion in the first method.

As a fourth method of producing dry powder, the following method can be cited: mixing the first powder of TFE-based polymer with the second powder of F polymer, heat-treating at a temperature exceeding 320°C to obtain a mixture, and then pulverizing the mixture ( The following is also referred to as "Method 4"). The fourth method can also be referred to as a method in which a powder composition containing the first powder and the second powder is heat-treated at a temperature exceeding 320° C., and then pulverized. The above-mentioned mixture (powder composition) may form a molten solidified product or an integrated product.

The first powder in the fourth method preferably has a TFE-based polymer as a main component. The content of the TFE-based polymer in the first powder is preferably 80% by mass or more, more preferably 100% by mass. In addition, in this specification, when the first powder contains components (surfactants, etc.) used in the production of the TFE-based polymer, the components are not included in components other than the TFE-based polymer. The D50 of the first powder is preferably 0.01-100 μm, more preferably 0.1-10 μm. The D90 of the first powder is preferably 200 μm or less, more preferably 20 μm or less. In this case, the interaction between the powders becomes good, and it is easy to further improve the physical properties of the fourth dry powder.

The second powder in the fourth method preferably has F polymer as a main component. The content of the F polymer in the second powder is preferably 80% by mass or more, more preferably 100% by mass. The D50 of the second powder is preferably 0.01 to 75 μm, more preferably 0.05 to 6 μm. The D90 of the second powder is preferably 100 μm or less, more preferably 6 μm or less.

The temperature in the above heat treatment exceeds 320°C, preferably 325 to 350°C, more preferably 330 to 345°C. If it is in this temperature range, the TFE-based polymer is prevented from melting excessively, and the F polymer can be sufficiently melted. Therefore, the F polymer can be firmly bonded by the TFE-based polymer. Furthermore, the heat treatment time is preferably 10 to 120 minutes, more preferably 15 to 100 minutes. As long as the obtained mixture is crushed, the fourth dry powder can be produced. When pulverizing, use jet mills, hammer mills, pin mills, bead mills, turbo mills, etc. appropriately. As a specific example of the grinding method, the method described in International Publication No. 2016/017801 can be cited.

The dry powder of the present invention and its production method have been described above, but the present invention is not limited to the configuration of the above-mentioned embodiment. For example, the dry powder of the present invention may be added with any other configuration to the configuration of the above-mentioned embodiment, or can be replaced with any configuration that performs the same function. In addition, the method of manufacturing the dry powder of the present invention may have other optional steps added to the constitutions of the above-mentioned embodiments, or may be replaced with any step that produces the same effect. [Example]

Hereinafter, the present invention will be described in detail with examples, but the present invention is not limited to them. The various measurement methods are shown below. ＜D50 and D90 of powder＞ Use a laser diffraction and scattering particle size distribution measuring device (“LA-920 measuring device” manufactured by Horiba Manufacturing Co., Ltd.) to disperse the powder in water for measurement. ＜Peel strength of laminated body＞ Fixed and cut into a rectangular shape (length: 100 mm, width: 10 mm) at a position where one end of the laminated body in the longitudinal direction is 50 mm away from the longitudinal direction at a stretching speed of 50 mm/min One end peeled the copper foil and the coating film at an angle of 90° with respect to the laminate, and the maximum load applied at this time was measured as the peel strength (N/cm).

The materials used are shown below. [Polymer] F polymer 1: Copolymer containing TFE unit, NAH unit and PPVE unit in order of 97.9 mol%, 0.1 mol%, 2.0 mol% (melting temperature: 300℃, 380℃ melting Viscosity: 3×10 ⁵ Pa·s or less) Non-F polymer 1: A copolymer with no oxygen-containing polar group containing TFE units and PPVE units in order of 98.0 mol% and 2.0 mol% (melting temperature: Melt viscosity at 305°C and 380°C: 3×10 ⁵ Pa·s or less) PTFE1: Fibrous PTFE containing 99.9 mol% or more of TFE-based units (standard specific gravity: 2.18, melt viscosity at 380°C: 3.0× 10 ⁹ Pa·s, melting temperature: over 320℃)

[Powder] First powder 1: Powder of F polymer 1 (D50: 0.3 μm, D90: 1.8 μm) First powder 2: Powder of F polymer 1 (D50: 1.8 μm) Powder A: Non-F polymer 1 Powder (D50: 0.3 μm, D90: 1.5 μm) Powder B: Powder of non-F polymer 1 (D50: 1.8 μm) Second powder 1: PTFE1 powder (D50: 0.3 μm); Furthermore, the second Powder 1 can be obtained as an aqueous dispersion of PTFE1. [Dispersant] Fluorine monohydric alcohol: F(CF ₂ ) ₆ CH ₂ (OCH ₂ CH ₂ ) ₇ OCH ₂ CH(CH ₃ )OH (fluorine content: 34% by mass, hydroxyl value: 78 mgKOH/g)

[Example 1] Production example of powder dispersion liquid [Example 1-1] Production example of powder dispersion liquid 11 Dispersion containing 30 parts by mass of the first powder 1, 5 parts by mass of fluoromonohydric alcohol 1 and 65 parts by mass of water Liquid; mixed with an aqueous dispersion containing 50% by mass of the second powder 1. Thereby, each powder is dispersed in water to obtain a powder dispersion 11 containing 90% by mass of PTFE1 and 10% by mass of F polymer 1 relative to the total of PTFE1 and F polymer 1 (mass of F polymer 1/ The quality of PTFE1: 0.11). [Example 1-2] Production example of powder dispersion A Except for using powder A instead of the first powder 1, the powder dispersion 1A was obtained in the same manner as in Example 1-1.

[Example 2] Coaggregation example of powder dispersion [Example 2-1] Production example of dry powder 11 Add water and adjust so that the polymer content in powder dispersion 11 becomes 10% by mass. If the temperature is 20°C When the powder dispersion is stirred vigorously, a wet powder or wet powder is formed. The wet powder was recovered and dried at 200°C to obtain dry powder 11. [Example 2-2] Production example of dry powder 1A Except for using powder dispersion 1A instead of powder dispersion 11, the dry powder 1A was obtained in the same manner as in Example 2-1.

[Example 3] Forming example of dry powder [Example 3-1] Manufacturing example of stretched sheet 11 First, 100 parts by mass of dry powder 11 and 40 parts by mass of lubricating oil ("ISOPAR-H( manufactured by Exxon) Registered trademark)”) is mixed to obtain a mixture. Then, the mixture was left at 25°C for 2 hours, and then extruded using a paste extrusion device (cylinder diameter: 60 mm, die diameter: 8 mm) to obtain extruded beads. Then, the extruded beads were supplied to a pair of 250 mm diameter calender rolls, rolled at 55°C, processed into a rolled film with a thickness of 1000 μm, and then heated to 85°C for drying to obtain a sheet. Using a biaxial stretching test device, the sheet was biaxially stretched under the conditions of a temperature of 300°C, a preheating of 3 minutes, and a stretching speed of 2 m/min to obtain a stretched sheet 11. In addition, the size of the stretched sheet 11 is set to be equal to the size of the sheet before stretching, both longitudinally and laterally, and the stretch magnification is set to 200%.

[Example 3-2] Manufacturing example of stretched sheet 1A Except that dry powder 1A was used instead of dry powder 1, stretched sheet 1A was obtained in the same manner as in Example 3-1. Each stretched sheet is a porous membrane. If the state of the pores is compared, the pore size distribution will be stretched sheet 11 and stretched sheet 1A in order from small to large. Furthermore, if the stretched sheet 11 and a commercially available PTFE sheet are thermocompression bonded (temperature: 300°C, pressure: 1 MPa, time: 60 minutes), the two sheets are firmly bonded.

[Example 4] Production example of powder dispersion [Example 4-1] Production example of powder dispersion 21 Dispersion containing 30 parts by mass of first powder 1, 5 parts by mass of fluoromonohydric alcohol 1, and 65 parts by mass of water Liquid; mixed with an aqueous dispersion containing 50% by mass of the second powder 1. Thereby, each powder is dispersed in water to obtain a powder dispersion 21 containing 50% by mass of PTFE1 and 50% by mass of F polymer 1 relative to the total of PTFE1 and F polymer 1 (mass of F polymer 1/ The quality of PTFE1: 1.0). [Example 1-2] Production example of powder dispersion 2A Except for using powder 2A instead of first powder 1, the powder dispersion 2A was obtained in the same manner as in Example 4-1.

[Example 5] Manufacturing example of dry powder [Example 5-1] Manufacturing example of dry powder 21 The petri dish filled with the powder dispersion 21 was exposed to an environment of -20°C, and the powder dispersion 21 was frozen. Then, the petri dish is moved to a decompression container whose temperature has been adjusted to -5°C, and the pressure in the decompression container is decompressed with a vacuum pump to start the sublimation of water. Measure the quality of the petri dish over time, stop the decompression when the mass change rate (g/hr) is within ±1%, and recover the contents of the petri dish to obtain a dry powder containing F polymer 1 and PTFE1 twenty one. [Example 5-2] Production example of dry powder 2A Except for using powder dispersion 2A instead of powder dispersion 21, the dry powder 2A was obtained in the same manner as in Example 5-1.

[Example 6] Coating example of laminated body [Example 6-1] Manufacturing example of laminated body 21 Using an electrostatic coating machine, dry powder 21 is supplied from the tank to the coating gun, and sprayed from the coating gun toward the surface of the copper foil The electrostatic coating dry powder 21. Then, the copper foil coated with dry powder 21 was kept at 340°C for 10 minutes, and then cooled to 25°C to obtain a copper foil and a coating film formed on the surface of the copper foil (calcined product of dry powder 21) ) Of the laminated body 21. Furthermore, the average thickness of the coating film is 60 μm, the difference between the maximum thickness and the minimum thickness is less than 3 μm, and the peel strength between the copper foil and the coating film is more than 10 N/cm. Also, no clogging of the painting gun occurred during electrostatic painting. [Example 6-2] Production example of laminated body 2A Dry powder 2A is used instead of dry powder 1. Except for this, the copper foil and the coating film formed on the surface of the copper foil (dry type) are obtained in the same manner as in Example 6-1. Laminated body 2A of powder 2A (calcined product). Furthermore, the average thickness of the coating film is 60 μm, the difference between the maximum thickness and the minimum thickness is 10 μm, and the peel strength between the copper foil and the coating film is 1 N/cm.

[Example 7] Manufacturing example of dry powder [Example 7-1] Manufacturing example of dry powder 41 First, 120 parts by mass of the second powder 1 and 10 parts by mass of the first powder 2 were mixed, and in the atmosphere, Heat treatment at 325°C for 120 minutes to obtain a mixture. After the mixture was slowly cooled to 25°C, it was pulverized using a jet mill to obtain dry powder 41 having a D50 of 20 μm. [Example 7-2 (Comparative Example)] Production Example of Dry Powder 42 Except for changing the heat treatment temperature to 275°C, the dry powder 42 was obtained in the same manner as in Example 7-1. [Example 7-3 (Comparative Example)] Production Example of Dry Powder 43 Except that the first powder 2 was changed to Powder B, the dry powder 43 was obtained in the same manner as in Example 7-1.

[Example 8] Manufacturing example of laminate [Example 8-1] Manufacturing example of laminate 41 Using an electrostatic coating machine, dry powder 41 was supplied from the tank to the coating gun, and sprayed from the coating gun toward the surface of the copper foil Electrostatic coating dry powder 41. Then, the copper foil coated with dry powder 41 was kept at 340°C for 10 minutes and then cooled to 25°C. Thereby, a laminate (average thickness: 60 μm) having a copper foil and a calcined layer of the dry powder 41 formed on the surface of the copper foil was obtained. [Example 8-2 (Comparative Example)] Production Example of Layered Body 42 Except that the dry powder 41 was changed to dry powder 42, the layered body 42 was obtained in the same manner as in Example 8-1. [Example 8-3 (Comparative Example)] Production Example of Layered Body 43 Except that the dry powder 41 was changed to dry powder 43, the layered body 43 was obtained in the same manner as in Example 8-1.

<Evaluation of Adhesion> Measure the peel strength (N/cm) of the obtained laminate, and evaluate it according to the following criteria. [Evaluation Criteria] ○: 10 N/cm or more ×: less than 10 N/cm

<Evaluation of coating workability> The workability of coating work using electrostatic coating machines is evaluated according to the following standards. [Evaluation Criteria] ○: The composite powder is smoothly supplied from the tank to the coating gun, and the fibrillation of the composite powder during coating is suppressed, so the coating gun is not clogged. ×: The coating gun is easy to be clogged due to the fiberization of the composite powder during coating, and the spray is unstable. The results are summarized and shown in Table 1.

[Table 1] Table 1 Example 8-1 Example 8-2 Example 8-3 No. of multilayer body Laminated body 41 Laminated body 42 Laminated body 43 1st powder F polymer 1 F polymer 1 Non-F polymer 1 Heat treatment temperature [℃] 325 275 325 Continuity 〇 〇 X Coating workability 〇 X X [Industrial availability]

The dry powder of the present invention can be used to produce molded products such as films, impregnated materials (prepregs, etc.), laminates (metal laminates such as back-adhesive copper foil), and can be used to produce molded products that require mold release, electrical properties, and water repellency Molded products for oil, chemical resistance, weather resistance, heat resistance, sliding properties, abrasion resistance, etc. The molded product obtained from the dry powder of the present invention is useful as antenna parts, printed circuit boards, aircraft parts, automotive parts, sports equipment, food industry products, paints, cosmetics, etc., specifically, as wire coating materials (aircraft Electric wires, data transmission cables, plenum cables, coaxial cables, high-frequency cables, flat cables, heat-resistant cables, and other covering materials), electrical insulating tapes, insulating tapes for petroleum mining, materials for printed circuit boards, separation films ( Precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), replication rollers, furniture, automotive dashboards, Covers, sliding components (load bearings, sliding shafts, valves, bearings, gears, cams, belt conveyors, food conveyor belts, etc.), tools (shovels, files, awls, saws, etc.), boilers, Hoppers, pipes, ovens, baking molds, shoots, molds, toilets, and container covering materials are useful.

Claims (12)

A dry powder comprising a fluoropolymer having a tetrafluoroethylene-based unit and an oxygen-containing polar group, and a tetrafluoroethylene-based polymer. The dry powder of claim 1, wherein the melting temperature of the above-mentioned fluoropolymer is 140-320°C. The dry powder of claim 1 or 2, wherein the fluoropolymer includes a unit based on a monomer having the oxygen-containing polar group. The dry powder according to any one of claims 1 to 3, wherein the oxygen-containing polar group is a hydroxyl group-containing group or a carbonyl group-containing group. The dry powder of any one of claims 1 to 4, wherein the above-mentioned tetrafluoroethylene-based polymer is: polytetrafluoroethylene, a copolymer of tetrafluoroethylene and perfluoro (alkyl vinyl ether), tetrafluoroethylene and Copolymer of hexafluoropropylene, copolymer of tetrafluoroethylene and ethylene, or copolymer of tetrafluoroethylene and vinylidene fluoride. The dry powder of any one of claims 1 to 5, wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene. The dry powder according to any one of claims 1 to 6, wherein the ratio of the content of the fluoropolymer to the content of the tetrafluoroethylene-based polymer is 0.4 or less. A method for producing dry powder, which is the method for producing dry powder according to any one of claims 1 to 7, the method of producing is based on the first powder containing the above-mentioned fluoropolymer and the above-mentioned tetrafluoroethylene-based polymer. 2 In a powder dispersion of powder and water, the first powder and the second powder are coaggregated to obtain a wet powder, and the wet powder is dried to obtain the dry powder. A method for producing dry powders, which is the method for producing dry powders as claimed in any one of claims 1 to 7, wherein the production method comprises the first powder containing the above-mentioned fluoropolymer and the first powder containing the above-mentioned tetrafluoroethylene polymer 2 The powder dispersion liquid of powder and water is frozen, and the water is sublimated to remove it to obtain the above dry powder. A method for producing dry powders, which is the method for producing dry powders as claimed in any one of claims 1 to 7, wherein the production method comprises the first powder containing the above-mentioned fluoropolymer and the first powder containing the above-mentioned tetrafluoroethylene polymer 2 The powder dispersion liquid of powder and water is spray-dried to obtain the above-mentioned dry powder. A method for producing dry powders, which is the method for producing dry powders according to any one of claims 1 to 7, wherein the production method combines the first powder of the fluoropolymer and the second powder of the tetrafluoroethylene polymer The powder is mixed, heat-treated at a temperature exceeding 320°C to obtain a mixture, and the mixture is pulverized to obtain the above-mentioned dry powder. The manufacturing method of any one of claims 8 to 11, wherein the volume-based cumulative 50% particle size of the first powder is 0.01 to 75 μm, and the volume-based cumulative 50% particle size of the second powder is 0.01 to 100 μm .