WO2020149097A1 - Dry powder and method for producing dry powder - Google Patents

Abstract

[Problem] 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. [Solution] 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°C to 320°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 method for producing dry powder

The present invention relates to a predetermined dry powder and a manufacturing method thereof.

Powders of tetrafluoroethylene-based polymers such as polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (PFA), copolymers of tetrafluoroethylene and hexafluoropropylene (FEP) It has excellent physical properties such as properties, electrical characteristics, water and oil repellency, chemical resistance, weather resistance, and heat resistance, and is used for various industrial applications.

There is also an attempt to blend powders of different kinds of tetrafluoroethylene-based polymers to prepare powders having physical properties of the respective tetrafluoroethylene-based polymers.
As the method, a method of dry blending a powder of a heterogeneous tetrafluoroethylene-based polymer having no oxygen-containing polar group, in the above-mentioned method, further heating near the melting temperature of the tetrafluoroethylene-based polymer and then pulverizing (See Patent Document 1), a method of freeze-drying an aqueous dispersion of the powder (see Patent Document 2), a method of co-coagulating an aqueous dispersion containing the powder (see Patent Documents 3 to 5), the above A method of spray-drying an aqueous dispersion containing powder has been proposed (see Patent Document 6).

Japanese Patent Laid-Open No. 05-093086 Japanese Patent Publication No. 2009-523851 International Publication No. 2012/086710 International Publication No. 2012/086725 International Publication No. 2013/157647 Japanese Patent Publication No. 2010-533763

In the blending of powders of tetrafluoroethylene-based polymers with poor intermolecular interaction, when the dry blending method described in the prior art document is used, the obtained powder has low homogeneity and its molding processability and physical properties of molded articles are low. There is a problem that it is not enough. There is also a problem that when the mechanical stress in the blend is increased, the polymer is deteriorated and the handling property thereof is likely to be lowered. Further, in the method of heat treatment, there is also a problem that unless the heat treatment conditions, particularly the cooling after heating, are strictly controlled, the polymer is likely to be significantly deteriorated.

Further, in the method by co-coagulation, the method by freeze-drying or the method by spray-drying described in the prior art document, factors such as the type of polymer, its combination, the state of dispersion liquid (polymer concentration, state of powder, etc.), etc. However, the present inventors have found that the physical properties of the obtained powder are greatly affected. For example, it has been found that the powder obtained by the method by co-coagulation has improved moldability, but has low adhesiveness to the substrate.

On the other hand, a blend of different tetrafluoroethylene-based polymer powders using a tetrafluoroethylene-based polymer powder having an oxygen-containing polar group, and the physical properties of the blended powder are not known.
The present inventors have studied blending of powders of different types of tetrafluoroethylene-based polymers using powders of tetrafluoroethylene-based polymers having an oxygen-containing polar group, which have not been known so far. As a result, a powder that forms a molded article having excellent extrusion moldability, stretch moldability, and adhesiveness without impairing the physical properties of each polymer, and a highly adhesive powder suitable for electrostatic coating were obtained. ..

The present invention is a blend powder of different tetrafluoroethylene-based polymer powders using a tetrafluoroethylene-based polymer powder having an oxygen-containing polar group, wherein the physical properties of each polymer are highly expressed dry powders. For the purpose of provision.

The present invention provides the following inventions.
<1> A dry powder containing a fluoropolymer having a unit based on tetrafluoroethylene and an oxygen-containing polar group, and a tetrafluoroethylene-based polymer.
<2> The dry powder according to <1> above, wherein the fluoropolymer has a melting temperature of 140 to 320° C.
<3> The dry powder according to <1> or <2>, in which the fluoropolymer includes a unit based on the monomer having the oxygen-containing polar group.
<4> The dry powder according to 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 tetrafluoroethylene-based polymer is polytetrafluoroethylene, a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether), a copolymer of tetrafluoroethylene and hexafluoropropylene, a copolymer of tetrafluoroethylene and ethylene, or The dry powder according to any one of the above items <1> to <4>, which is a copolymer of tetrafluoroethylene and vinylidene fluoride.
<6> The dry powder according to any one of the above items <1> to <5>, wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.
<7> The dry powder according to any one of the above items <1> to <6>, wherein the ratio of the content mass of the fluoropolymer to the content mass of the tetrafluoroethylene-based polymer is 0.4 or less.
<8> A method for producing a dry powder according to any one of the above <1> to <7>, which comprises a first powder of the fluoropolymer, a second powder of the tetrafluoroethylene-based polymer, and water. A method for producing a dry powder, which comprises co-coagulating the first powder and the second powder in a dispersion to obtain a wet powder, and drying the wet powder to obtain the dry powder.
<9> A method for producing a dry powder according to any one of the above <1> to <7>, which comprises a first powder of the fluoropolymer, a second powder of the tetrafluoroethylene-based polymer, and water. A method for producing a dry powder, wherein the dispersion liquid is frozen, and water is sublimated and removed to obtain the dry powder.
<10> A method for producing a dry powder according to any one of the above items <1> to <7>, which comprises a first powder of the fluoropolymer, a second powder of the tetrafluoroethylene-based polymer, and water. A method for producing a dry powder, which comprises spray-drying a dispersion liquid to obtain the dry powder.
<11> The method for producing a dry powder according to any one of the above items <1> to <7>, wherein the first powder of the fluoropolymer and the second powder of the tetrafluoroethylene-based polymer are mixed, and the temperature is 320° C. A method for producing a dry powder, which comprises subjecting the mixture to a heat treatment at an ultra high temperature and pulverizing the mixture to obtain the dry powder.
<12> The volume-based cumulative 50% diameter of the first powder is 0.01 to 75 μm, and the volume-based cumulative 50% diameter of the second powder is 0.01 to 100 μm. <11> The manufacturing method according to any one of the above.

According to the present invention, a dry powder containing a fluoroolefin-based polymer having an oxygen-containing polar group and a tetrafluoroethylene-based polymer, which is particularly excellent in extrusion moldability and stretchability, and which can be a molded article exhibiting strong adhesiveness is provided. can get.

"Powder D50" is the volume-based cumulative 50% diameter, the particle size distribution is measured by the laser diffraction/scattering method, the cumulative volume is calculated with the total volume of the group of particles as 100%, and the cumulative volume is calculated on the cumulative curve. Is the particle size at the point where is 50%.
"Powder D90" is the volume-based cumulative 90% diameter, the particle size distribution is measured by the laser diffraction/scattering method, and the cumulative volume is calculated with the total volume of the group of particles as 100%, and the cumulative volume on the cumulative curve. Is the particle size at the point where is 90%.
The “unit based on a monomer” is a generic term for an atomic group directly formed by polymerizing one molecule of a monomer and an atomic group obtained by chemically converting a part of this atomic group. In the present specification, the unit based on the monomer is also simply referred to as “unit”.
The "melting temperature (melting point) of the polymer" is a temperature corresponding to the maximum value of the melting peak of the polymer measured by the differential scanning calorimetry (DSC) method.
The "melt viscosity of the polymer" is based on ASTM D1238, and a sample of the polymer (2 g) that had been heated for 5 minutes at the measurement temperature in advance was loaded with 0.7 MPa using a flow tester and a 2Φ-8L die. It is a value measured by holding at the measurement temperature.
The “viscosity of the powder dispersion” is a value measured with a B-type viscometer at room temperature (25° C.) under the condition of a rotation speed of 30 rpm. The measurement is repeated three times, and the average value of the three measured values is used.
The "thixo ratio of the powder dispersion liquid" is a value calculated by dividing the viscosity η ₁ measured under the condition of the rotation speed of 30 rpm by the viscosity η ₂ measured under the condition of the rotation speed of 60 rpm. The measurement of each viscosity is repeated three times, and the average value of the three measured values is used.
"Peel strength of laminated body" means fixing a position of 50 mm from one end in the longitudinal direction of the laminated body cut out in a rectangular shape (length 100 mm, width 10 mm), pulling speed 50 mm/min, one end in the longitudinal direction. Is the maximum load (N/cm) applied when the metal foil and the resin layer are separated from each other at 90° to the laminate.
The “unit” in a polymer may be an atomic group formed directly from a monomer by a polymerization reaction, and the polymer obtained by the polymerization reaction is treated by a predetermined method to convert an atomic group in which a part of the structure is converted. May be The unit based on the monomer A contained in the polymer is also simply referred to as “monomer A unit”.

The dry powder of the present invention includes a fluoropolymer (hereinafter, also referred to as “F polymer”) having a unit (TFE unit) based on tetrafluoroethylene (TFE) and an oxygen-containing polar group, and a tetrafluoroethylene-based polymer (hereinafter, referred to as “F polymer”). Also referred to as "TFE polymer"). The F polymer is a polymer different from the TFE polymer.
A molded product (including a molding site such as a polymer layer. The same applies hereinafter) formed from the dry powder of the present invention is excellent in extrusion moldability and stretchability and exhibits strong adhesiveness.

The reason for this is not clear, but in addition to the fact that both the F polymer and the TFE polymer are fluoropolymers containing TFE units and having high compatibility, the F polymer has an oxygen-containing polar group. That is, it is considered that the oxygen-containing polar group of the F polymer not only exhibits adhesiveness but also promotes interaction between the polymers, for example, formation of a matrix. As described above, since the homogeneity of the respective polymers in the dry powder is high, it is considered that the formation of the matrix is further promoted and the respective polymer chains are easily entangled uniformly. As a result, it is considered that a molded product having excellent extrusion moldability and stretchability and exhibiting strong adhesiveness was obtained.

The melting temperature of the F polymer is preferably 140 to 320°C, more preferably 200 to 320°C, and further preferably 260 to 320°C. In this case, it is easy to further improve the adhesiveness 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 a polymer end group, and may be surface-treated (radiation treatment, electron beam treatment, Corona treatment, plasma treatment, etc.) may be included in the polymer, and the former is preferable. The oxygen-containing polar group contained in the F polymer may be a group 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 in the polymerization of the polymer.

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

The hydroxyl group-containing group is preferably —CF ₂ CH ₂ OH, —C(CF ₃ ) ₂ OH, or a 1,2-glycol group (—CH(OH)CH ₂ OH).
Carbonyl-containing groups include >C(O), —CF ₂ C(O)OH, >CFC(O)OH, carboxamido groups (—C(O)NH _2, etc.), acid anhydride residues (—C( O)OC(O)-), imide residues (-C(O)NHC(O)- etc.), dicarboxylic acid residues (-CH(C(O)OH)CH ₂ C(O)OH etc.), Alternatively, a carbonate group (—OC(O)O—) is preferable.
The oxycycloalkane group is preferably an epoxy group or an oxetanyl group.

Oxygen-containing polar group, from the viewpoint of not easily impairing the adhesiveness and crack resistance of molded articles obtained from dry powder, is a polar group and is a cyclic group or its ring-opening group, a cyclic acid anhydride residue, a cyclic An imide residue, a cyclic carbonate group, a cyclic acetal group, a 1,2-dicarboxylic acid residue or a 1,2-glycol group is particularly preferred, and a cyclic acid anhydride residue is most preferred.

The F polymer includes a TFE unit, a unit based on hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE) or fluoroalkyl ethylene (FAE) (hereinafter, also referred to as “PAE unit”), and an oxygen-containing polar group. A polymer containing a unit (hereinafter, also referred to as “polar unit”) based on a monomer having a is preferable.
The proportion of TFE units is preferably 50 to 99 mol %, and more preferably 90 to 99 mol% based on all units constituting the F polymer.

The PAE unit is preferably a unit based on PAVE (hereinafter also referred to as “PAVE unit”) or a unit based on HFP (hereinafter also referred to as “HFP unit”), and more preferably a PAVE unit. Two or more types of PAE units may be used.
The proportion of PAE units is preferably 0 to 10 mol%, more preferably 0.5 to 9.97 mol%, based on all units constituting the F polymer.
The proportion of polar units is preferably 0.01 to 3 mol% based on all units constituting the F polymer.

The _{PAVE, CF 2 = CFOCF 3 (} PMVE), CF 2 = CFOCF 2 CF 3, CF 2 = CFOCF 2 CF 2 CF 3 (PPVE), CF 2 = CFOCF 2 CF 2 CF 2 CF 3, CF 2 = CFO _{(CF 2) 8} F can be mentioned, PMVE or PPVE is preferred.
The _{FAE, CH 2 = CH (CF} 2) 2 F (PFEE), CH 2 = CH (CF 2) 3 F, CH 2 = CH (CF 2) 4 F (PFBE), CH 2 = CF (CF 2 _{) 3 H, CH 2 = CF} (CF 2) 4 H can be mentioned, PFEE or PFBE is preferred.

The polarity unit may be one type or two or more types.
Specific examples of the monomer having an oxygen-containing polar group include itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride (also referred to as hymic acid anhydride; hereinafter also referred to as “NAH”). Maleic anhydride is mentioned, and a suitable specific example thereof is 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 unit may be one type or two or more types.
Examples of the monomer that forms another unit include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride (VDF), and chlorotrifluoroethylene (CTFE). Other units are preferably ethylene, VDF or CTFE, more preferably ethylene.
The proportion of the other units in the F polymer is preferably 0 to 50 mol %, more preferably 0 to 40 mol% based on all the units constituting the F polymer.

The dry powder of the present invention may contain various additives. As additives, ultraviolet absorbers, light stabilizers, matting agents, leveling agents, surface modifiers, surfactants, degassing agents, plasticizers, fillers, heat stabilizers, thickeners, dispersants, rust preventives. Agents, silane coupling agents, antifouling agents, antifouling agents, flame retardants and the like.

The TFE polymer is 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 copolymer of TFE and VDF. Is preferred, and PTFE is more preferred.
In addition to the homopolymer of TFE, PTFE also includes so-called modified PTFE, which is a copolymer of a very small amount of comonomer (PAVE, HFP, FAE, etc.) and TFE. Further, PFA may include units based on monomers other than TFE and PAVE. The same applies to the other copolymers described above.
As described above, the molded product not only exhibits strong adhesiveness and crack resistance, but also does not easily deteriorate the physical properties of the TFE polymer. For example, when the TFE-based polymer is PTFE, the fibrous surface physical properties and the porosity of the PTFE molded article are unlikely to be impaired in the molded article.

The PTFE is preferably non-heat-melting PTFE.
As described above, the dry powder of the present invention not only exhibits strong adhesiveness, but also does not easily deteriorate the physical properties of the TFE polymer. For example, when the TFE-based polymer is non-heat-melting PTFE, the blended powder is unlikely to lose the heat resistance originally possessed by the non-heat-melting PTFE powder.
The proportion of TFE units in the non-thermofusible PTFE is preferably 99.5 mol% or more, more preferably 99.9 mol% or more, based on all units.

The non-heat-melting PTFE preferably has a fibrillation property. If it has fibrillation property, the surface smoothness, mechanical properties (abrasion resistance, etc.), and weather resistance of the coating film obtained by electrostatic coating and firing of the dry powder of the present invention are likely to be improved. In addition, the non-thermofusible PTFE having fibrillation property means a PTFE capable of paste-extruding unbaked polymer powder. That is, it means PTFE having strength or elongation in a molded product obtained by paste extrusion.

The number average molecular weight of the non-thermofusible PTFE is preferably 300,000 to 300,000,000, more preferably 500,000 to 25,000,000.
The standard specific gravity, which is an index of the average molecular weight of the non-thermofusible PTFE, is preferably 2.14 to 2.22, more preferably 2.15 to 2.21.
The melt viscosity of the non-heat-melting 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.
When at least one of the number average molecular weight, the standard specific gravity and the melt viscosity of the non-thermofusible PTFE is in the above range, the non-thermofusible PTFE has better fibrillability and is excellent in mechanical properties and the like. Goods can be formed.

The TFE polymer is preferably a polymer obtained by emulsion-polymerizing a fluoroolefin in water.
For example, PTFE is preferably a polymer obtained by emulsion polymerization of TFE in water. The first PTFE powder is a powder in which a polymer obtained by emulsion polymerization of TFE in water is dispersed as particles in water. When using such powder, the powder dispersed in water may be used as it is, or the powder may be recovered from water and used.

The TFE polymer may be modified by surface treatment (radiation treatment, electron beam treatment, corona treatment, plasma treatment, etc.). Examples of such a surface treatment method include the methods described in International Publication No. 2018/026012 and International Publication No. 2018/026017.
The TFE polymer is widely available as a powder or a dispersion thereof as a commercial product.

The ratio of the mass of the F polymer to the mass of the TFE polymer (content of F polymer/content of TFE 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 is good, and it is easy to obtain a dry powder that is particularly excellent in extrusion moldability and stretch moldability. The lower limit of the mass ratio is usually 0.01.

In a preferred embodiment of the dry powder of the present invention, the first powder and the second powder are contained in a powder dispersion liquid containing a first powder of F polymer, a second powder of TFE polymer, and water. Dry powder obtained by co-coagulation and further drying (hereinafter also referred to as "first dry powder"), first powder of F polymer, second powder of TFE polymer, and powder containing water A dry powder (hereinafter, also referred to as “second dry powder”) obtained by freezing the dispersion liquid and sublimating and removing water; a first powder of F polymer; a second powder of TFE polymer; Dry powder obtained by spray drying a powder dispersion containing water (hereinafter, also referred to as “third dry powder”), a first powder of F polymer, and a second powder of TFE polymer are mixed. A dry powder (hereinafter, also referred to as “fourth dry powder”) obtained by heat-treating at more than 320° C. to obtain a mixture and pulverizing the mixture.

It can be said that the first dry powder is a powder in which the F polymer and the TFE polymer are uniformly mixed. This does not depend on the blending ratio of each polymer.
The reason for this is not clear, but in addition to the fact that both the F polymer and the TFE polymer are fluoropolymers containing TFE units and having high compatibility, the F polymer has an oxygen-containing polar group. That is, since the F polymer has an oxygen-containing polar group, it has high stability in an aqueous medium and interacts with the TFE polymer, and thus it is considered that the respective powders are in a uniformly dispersed state. It is considered that when the powder dispersion liquid in such a good dispersion state is subjected to co-coagulation treatment, co-coagulation of the first powder and the second powder proceeds in such a manner that the powders are rolled up, and as a result, a homogeneous powder is obtained. Is believed to have been obtained.
The D50 of the first dry powder is preferably 100 to 1000 μm, more preferably 300 to 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 according to JIS K6892.

The first dry powder is preferably obtained by the first method described later.
The first dry powder is particularly excellent in extrusion moldability and stretch moldability, and the obtained molded product exhibits strong adhesiveness. A stretched sheet is obtained by extruding the first powder to obtain a sheet and subjecting the sheet to a stretching treatment. As a stretching condition, a stretching ratio of 200% or more can be adopted at a speed of 5 to 1000%/sec.
A coating material can also be obtained by extruding the first dry powder.
In the former extrusion molding of the first dry powder, if the TFE-based polymer is fibrillar high-molecular-weight PTFE, a porous stretched membrane can also be produced.

A known method can be adopted for each extrusion molding method.
For example, the extrusion molding method for molding the first dry powder into a sheet is preferably a method in which extruded beads obtained by paste extrusion of fine powder are molded into a sheet by calendering or the like.
In this case, the first dry powder may contain a lubricant represented by petroleum hydrocarbons such as naphtha. The mixing ratio of the lubricant is usually 15 to 30 parts by mass with respect to 100 parts by mass of the fine powder.

It can be said that the second dry powder is a highly homogeneous dry powder containing the F polymer and the TFE polymer. This does not depend on the blending ratio of each polymer.
The second dry powder has the physical properties of the original TFE polymer and is an adhesive powder suitable for electrostatic coating.
The reason for this is not clear, but in addition to the fact that both the F polymer and the TFE polymer are fluoropolymers containing TFE units and having high compatibility, the F polymer has an oxygen-containing polar group. That is, it is considered that the oxygen-containing polar group of the F polymer not only exhibits adhesiveness but also balances the electrostatic properties of the entire dry powder and promotes interaction between polymers, for example, formation of a matrix. .. As described above, since the dry powder has high homogeneity, it is considered that the formation of this matrix is further promoted and that the respective polymer chains are easily entangled uniformly. As a result, it is considered that good electrostatic paintability and excellent adhesiveness were exhibited without impairing the physical properties of the original TFE polymer.

The second dry powder may be further subjected to various post-treatments depending on its use. Examples of such post-treatment include crushing treatment with 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 further 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 highly uniform powder of the F polymer and the TFE polymer, and it is easy to keep the electric potential of the powder surface neutral and further easily reduce the angle of repose.
The angle of repose of the second dry powder is preferably 50° or less, more preferably 35° or less. The lower limit of the angle of repose is not particularly limited and is usually 5°. In this case, the dry powder can be smoothly supplied to the coating device in electrostatic coating, and the surface smoothness, thickness uniformity, and workability of the coating film are excellent.
The angle of repose is determined by measuring dried dry powder according to "JIS R 9301-2-2 Alumina powder-Part 2: Physical property measurement method-2: Angle of repose".

When the second dry powder is electrostatically coated on the surface of the base material and the base material is heated to form the second dry powder fired product, the base material and the dry powder fired product are laminated in this order. A laminated body (painted article) is obtained.
The coated article has a base material and a fired product that is a coating film formed from the second dry powder on the base material, and is excellent in adhesiveness, surface smoothness, thickness uniformity, and workability.

The material of the base material is not particularly limited, and examples thereof include an inorganic material, an organic material, and an organic-inorganic composite material. Examples of the inorganic substance include concrete, natural stone, glass and metal (iron, stainless steel, aluminum, copper, brass, titanium, etc.). Examples of organic substances include plastics, rubbers, adhesives, and wood. Examples of the organic-inorganic composite material include fiber-reinforced plastic, resin-reinforced concrete, and fiber-reinforced concrete. Further, the base material may be subjected to a known surface treatment (chemical conversion treatment or the like).
The material of the base material is preferably metal, and more preferably aluminum or copper.

The thickness of the coating film of the coated article can be appropriately set depending on the use of the coated article, and is preferably 1 to 1000 μm, more preferably 20 to 300 μm.
Painted articles include building exterior members such as roofs, aluminum composite panels, curtain panel aluminum panels, curtain wall aluminum frames, aluminum window frames; road materials such as traffic lights, telephone poles, road marking poles, and guardrails; automobile bodies. And parts (bumpers, wiper blades, tire wheels, etc.); household appliances (outdoor units for air conditioners, exteriors of water heaters, etc.); blades for wind power generators, solar battery backsheets, backsides of solar heat collecting mirrors, eggplant battery exteriors , A generator.

In manufacturing the coated article, the second dry powder may be electrostatically coated and heated at the same time, or the base material may be heated after the second dry powder is electrostatically coated on the surface of the base material. ..
The heating temperature of the electrostatically coated second dry powder is usually 260 to 380°C. The time for maintaining the heating temperature is usually 1 to 60 minutes.
As a means for electrostatically coating the second dry powder, an electrostatic coating method of supplying the dry powder from the tank to the coating gun and discharging (spraying) the second dry powder from the coating gun to the surface of the base material Is preferred.
The discharge rate of the second dry powder (powder paint) from the coating gun can be set to 50 to 200 g/min.

The distance from the tip of the coating gun (that is, the discharge port of the second dry powder) to the surface of the base material is preferably 150 to 400 mm from the viewpoint of coating efficiency.
When the electrostatic coating method is carried out industrially, it is preferable to lay a grounded conductive horizontal belt conveyor in the coating chamber and install the coating gun vertically above the horizontal belt conveyor in the coating chamber. The width of the coating pattern is preferably 50 to 500 mm, the operating speed of the coating gun is preferably 1 to 30 m/min, and the conveyor speed is preferably 1 to 50 m/min.
After the second dry powder is electrostatically coated on the surface of the base material and the base material is heated to form a coating film, the coated article may be cooled to room temperature (20 to 25° C.). The cooling may be either rapid cooling or slow cooling, and slow cooling is preferable from the viewpoint of suppressing peeling of the coating film from the substrate.

It can be said that the third dry powder is a powder in which the F polymer and the TFE polymer are uniformly mixed. This does not depend on the blending ratio of each polymer.
Although the reason is not always clear, as described above, since the water dispersion liquid in which each powder is uniformly dispersed is subjected to spray drying (spray dry), the first powder and It is considered that a homogeneous powder with 2 powders was formed.

The D50 of the third dry powder is preferably 1 to 100 μm, more preferably 3 to 50 μm.
Similar to the first dry powder or the second dry powder, the third dry powder can be processed into a stretched sheet or a porous stretched film having excellent adhesiveness by subjecting it to extrusion molding and stretch molding. Further, when subjected to electrostatic coating, a coated article having excellent adhesiveness, surface smoothness, thickness uniformity and workability can be formed.

The fourth dry powder also contains the TFE polymer and the F polymer with high uniformity, and is excellent in adhesiveness and fibril resistance.
The reason is not always clear, but it can be considered as follows.
If the temperature of the heat treatment for obtaining the mixture exceeds 320° C., the melting temperature of the F polymer is likely to be exceeded, and the melting temperature of the TFE polymer is likely to be around the melting temperature. Therefore, in the heat treatment, the TFE polymer is in a gelled (softened) state and the F polymer is in a highly melted state, so that both are easily bound or fused. At this time, it is considered that the F polymer having an oxygen-containing polar group increases the interaction with the TFE polymer and forms a matrix in the mixture to suppress the crystallization of the TFE polymer. Further, it is considered that since the fourth dry powder was obtained by pulverizing the mixture, a powder having high uniformity between the TFE polymer and the F polymer was obtained.

Therefore, it is presumed that the fourth dry powder exhibited high adhesiveness and high fibril resistance due to the action of the F polymer having an oxygen-containing polar group. Such a tendency tends to be remarkable when the TFE polymer is PTFE whose melting temperature is higher than 320° C. and the F polymer has a melting temperature of 260 to 320° C.
That is, the TFE-based polymer in the fourth dry powder is preferably PTFE having a melting temperature of higher than 320° C., and is preferably the non-melting PTFE described above. The melting temperature of the F polymer in the fourth dry powder is preferably 260 to 320°C.
Further, the fourth dry powder retains the original physical properties (heat resistance, etc.) of the TFE polymer well, and thus can be suitably used as a powder coating material for electrostatic coating, for example. Specifically, like the second dry powder, the fourth dry powder can form a coated article excellent in adhesiveness, surface smoothness, thickness uniformity, and processability when subjected to electrostatic coating. ..

The melt viscosity of the F polymer at 380° C. in the fourth dry powder 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 increased, the binding force of the F polymer to the TFE polymer can be further improved.
The ratio of the mass of the TFE-based polymer to the mass of the F-polymer in the fourth dry powder (content of TFE-based polymer/content of F-polymer) is preferably 5 or more, more preferably 5 to 50, and more preferably 10 to 25. More preferable. In this case, the interaction between the powders becomes good, and the TFE polymer and the F polymer are likely to be present more uniformly in the fourth dry powder. Therefore, it is easy to obtain a powder having particularly excellent adhesiveness without impairing the physical properties of the TFE polymer.

The fourth dry powder is a powder containing PTFE and F polymer.
The fourth dry powder may be further subjected to various post-treatments depending on its use. Examples of such post-treatment include radiation treatment, corona treatment, electron beam treatment, and plasma treatment.
The D50 of the fourth dry powder is preferably 0.1 to 50 μm, more preferably 0.3 to 40 μm, still more preferably 1 to 30 μm.
The D90 of the fourth dry powder is preferably 80 μm or less, more preferably 65 μm or less, even more preferably 40 μm or less.

The first dry powder is produced by co-coagulating the first powder and the second powder in a powder dispersion liquid containing the first powder of the F polymer, the second powder of the TFE polymer, and water. A method of obtaining wet powder and drying the wet powder (hereinafter, also referred to as “first method”) can be mentioned.
It can be said that this powder dispersion liquid is a dispersion liquid in which each of the first powder and the second powder is dispersed in the form of particles in an aqueous medium containing water as a main component.
It can be said that the dry powder obtained by the first method is a fine powder obtained by co-coagulation of the first powder and the second powder, in which the F polymer and the TFE polymer are highly uniformly mixed. This does not depend on the blending ratio of each polymer.

The reason for this is not clear, but in addition to the fact that both the F polymer and the TFE polymer are fluoropolymers containing TFE units and have high compatibility, the F polymer has an oxygen-containing polar group. That is, since the F polymer has an oxygen-containing polar group, it has high stability in an aqueous medium and interacts with the TFE polymer, and thus it is considered that the respective powders are in a uniformly dispersed state. It is considered that when the powder dispersion liquid in such a good dispersion state is subjected to co-coagulation treatment, co-coagulation of the first powder and the second powder proceeds in such a manner that the powders are rolled up with each other. It is believed that a powder was obtained.

The respective ranges of the oxygen-containing polar group and the F polymer contained in the F polymer in the first method are the same as those in the dry powder of the present invention, including the preferable range.
The first powder in the first method may contain a component other than the F polymer, but it is preferable that the F powder is the main component. The content of the F polymer in the first powder is preferably 80% by mass or more, and 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 further 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 polymer in the first method is the same as the range of the TFE polymer in the dry powder of the present invention, including the preferable range.

The second powder is preferably a powder in which a polymer obtained by emulsion-polymerizing a fluoroolefin in water is dispersed as particles in water. When using such powder, the powder dispersed in water may be used as it is, or the powder may be recovered from water and used.
The second powder in the first method may contain a component other than the TFE-based polymer, but it is preferable that the second powder contains the TFE-based polymer as a main component. The content of the TFE polymer in the second powder is preferably 80% by mass or more, more preferably 100% by mass. In the present specification, when the second powder contains a component (surfactant or the like) used in the production of the TFE polymer, the component is not included in the components other than the TFE polymer.

The D50 of the second powder is preferably 0.01 to 100 μm, more preferably 0.1 to 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 the co-coagulability of the first powder and the second powder and the physical properties of the molded product are likely to be further improved.

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 μm. The above-mentioned aspect is 1 μm or less, the D50 of the first powder is 1 μm or more and 4 μm or less, and the D50 of the second powder is 0.1 μm or more and 1 μm or less. In the former embodiment, it is easy to obtain a molded product that is particularly excellent in extrusion moldability and stretch moldability. In the latter embodiment, a molded article having excellent crack resistance can be easily obtained.

The ratio of the mass of the F polymer to the mass of the TFE polymer (content of F polymer/content of TFE 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 is good, and the co-coagulability of the first powder and the second powder is likely to be further improved. Therefore, without impairing the physical properties of the TFE polymer, the first dry powder having particularly excellent extrusion moldability and stretch moldability can be obtained, and a molded product having particularly excellent adhesiveness can be easily obtained. The lower limit of the mass ratio is usually 0.01.
The total proportion of the F polymer and the TFE polymer in the powder dispersion liquid in 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 improving the dispersibility of each powder and improving their co-condensation properties. The components used for producing the polymer (for example, the surfactant used for emulsion-polymerizing the fluoroolefin) do not correspond to the dispersant in the first method.
The dispersant is preferably a compound having a hydrophobic site and a hydrophilic site, and examples thereof include an acetylene-based surfactant, a silicone-based surfactant, and a fluorine-based surfactant. These dispersants are preferably nonionic.
The dispersant is preferably fluoroalcohol, more preferably fluoromonool or fluoropolyol.

The fluorine content of fluoromonool is preferably 10 to 50% by mass, more preferably 10 to 45% by mass, and further preferably 15 to 40% by mass.
The fluoromonool is preferably nonionic.
The hydroxyl value of fluoromonool is preferably 40 to 100 mgKOH/g, more preferably 50 to 100 mgKOH/g, and further preferably 60 to 100 mgKOH/g.

The fluoromonool is preferably a compound represented by the following formula (a).
Formula _{^{(a): R a - (}} OQ a) ma -OH
The symbols in the formulas have the following meanings.
R ^a represents a polyfluoroalkyl group or a polyfluoroalkyl group containing an etheric oxygen atom, and is —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 are preferred.
Q ^a represents an alkylene group having 1 to 4 carbon atoms, and is preferably an ethylene group (—CH ₂ CH ₂ —) or a propylene group (—CH ₂ CH(CH ₃ )—). Q ^a may be composed of two or more kinds of groups. When it is composed of two or more kinds of groups, the groups may be arranged in a random pattern or a block pattern.
ma represents an integer of 0 to 20, preferably an integer of 4 to 10.
The hydroxyl group of fluoromonool is preferably a secondary hydroxyl group or a tertiary hydroxyl group, more preferably a secondary hydroxyl group.

Examples of fluoro _{monool, 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 and the like.
Such fluoromonool can be obtained as a commercially available product (such as “Fluowet N083” and “Fluowet N050” manufactured by Arkroma Co.).

The fluorine content of the fluoropolyol is preferably 10 to 50% by mass, more preferably 10 to 45% by mass, and even more preferably 15 to 40% by mass.
The fluoropolyol is preferably nonionic.
The hydroxyl value of the fluoropolyol is preferably from 10 to 35 mgKOH/g, more preferably from 10 to 30 mgKOH/g, even more preferably from 10 to 25 mgKOH/g.
The weight average molecular weight of the fluoropolyol is preferably 2000 to 80000, more preferably 6000 to 20000.
The fluoropolyol is preferably a fluoropolyol containing units based on fluoro(meth)acrylate. In addition, "(meth)acrylate" is a general term for acrylate and methacrylate.

The fluoro(meth)acrylate is preferably a monomer represented by the following formula (f).
Formula (f): CH ₂ =CX ^f C(O)O-Q ^f -R ^f
The symbols in the formulas have 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 carbon atoms or an oxyalkylene group having 2 to 4 carbon atoms.
R ^f represents a polyfluoroalkyl group having 1 to 6 carbon atoms, a polyfluoroalkyl group having 3 to 6 carbon atoms containing an etheric oxygen atom, or a polyfluoroalkenyl group having 4 to 12 carbon atoms, and —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 is preferred.

Specific examples of the fluoro(meth)acrylate include CH ₂ ═CHC(O)OCH ₂ CH ₂ (CF ₂ ) ₄ F and 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 and the like.

Preferable specific examples of the fluoropolyol include copolymers of the monomer represented by the above formula (f) and the monomer represented by the following formula (o).
Formula (o): CH ₂ =CX ^o C(O)-(OZ ^o ) _mo —OH
The symbols in the formulas have 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, and an ethylene group (—CH ₂ CH ₂ —) is preferable.
mo is an integer of 1 to 200, preferably an integer of 4 to 30.
In addition, Z ^o may be composed of two or more kinds of groups. In this case, the arrangement of different alkylene groups may be random or block.

Specific examples of the monomer represented by the formula (o) include 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 and the like.

The fluoropolyol may be composed only of a unit based on the monomer represented by the formula (f) and a unit based on the monomer represented by the formula (o), and may further include another unit. ..
The content of the unit based on the monomer represented by the formula (f) is preferably 60 to 90 mol% and more preferably 70 to 90 mol% with respect to all the units contained in the fluoropolyol.
The content of the unit based on the monomer represented by the formula (o) is preferably 10 to 40 mol% and more preferably 10 to 30 mol% with respect to all units contained in the fluoropolyol.
The total content of the units based on the monomer represented by the formula (f) and the monomer represented by the formula (o) is preferably 90 to 100 mol %, based on all units contained in the fluoropolyol, and 100 Mol% is more preferred.
The proportion of fluoroalcohol in the powder dispersion is preferably 10% by mass or less, more preferably 1% by mass or less, and further preferably 0.01% by mass or less. The lower limit of the above ratio is usually more than 0%.

The powder dispersion liquid in the first method contains an aqueous medium containing water as a main component (dispersion medium of the powder dispersion liquid).
The aqueous medium may consist only of water, or may consist of water and a water-soluble compound.
However, the water-soluble compound is preferably a compound which is liquid at 25° C., does not react with the F polymer and the TFE polymer, and can be easily removed by heating or the like. The proportion of water in the aqueous medium is preferably 95% by mass or more, more preferably 99% by mass or more, and further preferably 100% by mass.
The proportion of the aqueous medium in the powder dispersion is preferably 15 to 65% by mass, more preferably 25 to 50% by mass. In this range, the coaggregation property of the powder dispersion is particularly excellent.

Examples of the co-coagulation method in the first method include a method in which a powder dispersion having a polymer content adjusted is stirred to co-coagulate the dispersed first powder and second powder.
At this time, the content of the polymer is preferably 8 to 25% by mass. If necessary, the powder dispersion liquid may be diluted with water so as to obtain such a content.
The temperature in the co-coagulation is preferably 5 to 30°C.
In the co-coagulation, the pH of the powder dispersion may be adjusted if necessary. Moreover, you may add a pH adjuster, an electrolyte, an organic solvent, and an aggregation aid to a powder dispersion liquid.

Examples of pH adjusters include sodium carbonate, sodium hydrogen carbonate, ammonia, ammonium salts, and urea.
Examples of the electrolyte include inorganic salts such as potassium nitrate, sodium nitrate, sodium carbonate and sodium hydrogen carbonate.
Examples of the organic solvent include alcohol and acetone.
Examples of the coagulation 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 powder dispersion is stirred to co-coagulate the first powder and the second powder, and the coagulated powder is separated from the aqueous medium to obtain a wet powder. At this time, it is preferable to adjust the particle size by a granulating step or a sizing step. The granulation step is a step of granulating D50 of the coagulated powder to 100 to 1000 μm, and the sizing step is a step of adjusting the particle properties and particle size distribution of the coagulated powder by stirring.
As a result, wet powder, which is fine powder (coagulated powder) in a wet state, is obtained.

The powder dispersion used for co-coagulation is a method of mixing a dispersion containing the first powder and water with a dispersion containing the second powder and water, a dispersion containing the first powder and water and a second powder. It can be prepared by a method of mixing and a dispersion of the second powder and water and a method of mixing the first powder. However, the powder dispersion is preferably prepared by the former method from the viewpoint that each component is easily dispersed uniformly.

Next, the obtained wet powder is dried to obtain a first dry powder.
The drying temperature is preferably 110 to 250°C, more preferably 120 to 230°C. In this case, it is easy to balance the productivity of the first dry powder with the extrusion moldability.

The second dry powder is produced by freezing a powder dispersion containing a first powder of F polymer, a second powder of TFE polymer, and water, and sublimating and removing water from the frozen powder dispersion. A method (hereinafter, also referred to as a “second method”) is included.
It can be said that this dispersion liquid is a dispersion liquid in which each of the first powder and the second powder is dispersed in water in the form of particles.
It can be said that the second dry powder obtained by the second method is a highly homogeneous dry powder containing an F polymer and a TFE polymer, which is obtained by removing water from a frozen powder dispersion liquid by sublimation. .. This does not depend on the blending ratio of each polymer.

Although the reason is not always clear, as described above, when the powder dispersion liquid in which the respective powders are uniformly dispersed is frozen, the frozen product in which the first powder and the second powder are taken in as it is is It is thought to be obtained. It is considered that since the sublimated water was removed from the frozen product, a homogeneous dry powder containing the F polymer and the TFE polymer was obtained.

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

In addition, a preferable 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.
The range of the ratio of the mass of the F polymer to the mass of the TFE polymer (content of the F polymer/content of the TFE polymer) in the second method, including the preferable range, is the same as that in the first method. The same is true.
The range of the powder dispersion liquid in the second method is the same as that in the first method, including the preferable range.

Freezing of the powder dispersion in the second method is preferably performed at less than 0°C. Specifically, it is preferable to freeze the powder dispersion by exposing it to an atmosphere of −78 to −10° C. Freezing is preferably completed within 8 hours from the viewpoint of suppressing settling of the components of the powder dispersion liquid. Further, from the viewpoint of suppressing non-uniformity of the frozen product due to rapid freezing, it is preferable to freeze the powder dispersion for 10 minutes or more.
The removal of water from the frozen powder dispersion (frozen matter) by sublimation may be carried out under conditions in which melting of the powder dispersion is suppressed.
The temperature for sublimating water is preferably less than 0°C. Specifically, it is preferable to expose the frozen product to an atmosphere of −78 to +0° C. The pressure for sublimating water is usually a reduced pressure atmosphere, and a reduced pressure atmosphere of 0 to 6.12×10 ² Pa is preferable. The time for sublimation of water is usually 4 to 72 hours.
Examples of the apparatus used for sublimation include a centrifugal separator and a tray dryer.

As a method for producing a third dry powder, a method of spray-drying a powder dispersion liquid containing a first powder of F polymer, a second powder of TFE polymer and water (hereinafter, also referred to as “third method”) .) is mentioned.
It can be said that this dispersion liquid is a dispersion liquid in which each of the first powder and the second powder is dispersed in water in the form of particles.
It can be said that the dry powder obtained by the third method is a highly homogenous blend powder containing the F polymer and the TFE polymer, which is obtained by water evaporation of the powder dispersion by spray drying. This does not depend on the blending ratio of each polymer.

The reason is not always clear, but as mentioned above, when the powder dispersion liquid in which each powder is uniformly dispersed is spray-dried, water is volatilized and removed, and a homogeneous blended powder is likely to be formed as it is. Conceivable.
The third method is preferably carried out by spraying the powder dispersion liquid in an atmosphere above 100°C. As a specific method, in a system in which an inert gas (nitrogen gas is preferable) having a temperature of more than 100° C. is passed vertically upward, the powder dispersion is sprayed by a vertical downward method, and the powder dispersion is dried. Is preferred. An apparatus such as a crystallization tower can be used for this method.

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

Further, a preferable 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.
The range of the ratio of the mass of the F polymer to the mass of the TFE polymer (content of F polymer/content of TFE polymer) in the third method, including the preferable range, is the same as that in the first method. The same is true.
The range of the powder dispersion liquid in the third method is the same as that in the first method including the preferable range.

As a fourth method for producing dry powder, a method of mixing a first powder of TFE polymer and a second powder of F polymer, heat-treating at more than 320° C. to obtain a mixture, and further pulverizing the mixture (Hereinafter, also referred to as “fourth method”). It can be said that the fourth method is a method in which a powder composition containing the first powder and the second powder is heat-treated at a temperature higher than 320° C. and further pulverized. The mixture (powder composition) may form a melt-solidified product or an integrated product.

The first powder in the fourth method preferably contains a TFE polymer as a main component. The content of the TFE polymer in the first powder is preferably 80% by mass or more, more preferably 100% by mass. In addition, in the present specification, when the component (surfactant or the like) used in the production of the TFE-based polymer is contained in the first powder, the component is not included in the components other than the TFE-based polymer.
The D50 of the first powder is preferably 0.01 to 100 μm, more preferably 0.1 to 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 the physical properties of the fourth dry powder are likely to be further improved.

The second powder in the fourth method preferably contains an F polymer as a main component. The content of the F polymer in the second powder is preferably 80% by mass or more, and 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 heat treatment is more than 320°C, preferably 325 to 350°C, more preferably 330 to 345°C. Within such a temperature range, the F polymer can be sufficiently melted while preventing the TFE polymer from melting excessively. Therefore, the F polymer can be firmly bound to the TFE polymer.
The heat treatment time is preferably 10 to 120 minutes, more preferably 15 to 100 minutes.
A fourth dry powder can be produced by pulverizing the obtained mixture.
Jet mills, hammer mills, pin mills, bead mills, turbo mills and the like are preferably used for pulverization. Specific examples of the pulverizing method include the method described in International Publication No. 2016/017801.

Although the dry powder of the present invention and the manufacturing method thereof have been described above, the present invention is not limited to the configurations of the above-described embodiments.
For example, the dry powder of the present invention may have any other configuration added to the configuration of the above-described embodiment, or may be replaced with any configuration exhibiting the same function.
In addition, the method for producing a dry powder of the present invention may have other optional steps in addition to the configurations of the above-described embodiments, or may be replaced with an optional step that produces a similar action.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.
Various measuring methods are shown below.
<D50 and D90 of powder>
The powder was dispersed in water using a laser diffraction/scattering type particle size distribution measuring device (“LA-920 measuring device” manufactured by Horiba Ltd.) for measurement.
<Peel strength of laminate>
The position of 50 mm from one end in the length direction of the laminate cut out in a rectangular shape (length: 100 mm, width: 10 mm) was fixed, the pulling speed was 50 mm/min, and 90° from one end in the length direction to the laminate. Then, the maximum load applied when the copper foil and the coating film were peeled off was measured as the peeling strength (N/cm).

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

[powder]
First powder 1: F polymer 1 powder (D50: 0.3 μm, D90: 1.8 μm)
First powder 2: F polymer 1 powder (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); this second powder 1 is available as an aqueous dispersion of PTFE1.
[Dispersant]
Fluoro _{monool: F (CF 2) 6 CH} 2 (OCH 2 CH 2) 7 OCH 2 CH (CH 3) OH ( fluorine content: 34 wt%, hydroxyl value: 78 mgKOH / g)

[Example 1] Production Example of Powder Dispersion [Example 1-1] Production Example of Powder Dispersion 11 Dispersion containing 30 parts by mass of the first powder 1, 5 parts by mass of fluoromonool 1 and 65 parts by mass of water. And an aqueous dispersion containing 50% by mass of the second powder 1 were mixed. As a result, the respective powders are dispersed in water, and the powder dispersion 11 containing 90% by mass of PTFE1 and 10% by mass of F polymer 1 with respect to the total of PTFE1 and F polymer 1 (mass of F polymer 1/PTFE1 Mass: 0.11) was obtained.
[Example 1-2] Production Example of Powder Dispersion Liquid A A powder dispersion liquid 1A was obtained in the same manner as in Example 1-1, except that the powder A was used in place of the first powder 1.

[Example 2] Example of co-coagulation of powder dispersion [Example 2-1] Production example of dry powder 11 Water was added to adjust the content of the polymer in powder dispersion 11 to 10% by mass. When the powder dispersion was vigorously stirred at 20° C., a wet powder that was a dry powder in a wet state was formed. The wet powder was collected and dried at 200° C. to obtain dry powder 11.
[Example 2-2] Production Example of Dry Powder 1A Dry powder 1A was obtained in the same manner as Example 2-1, except that powder dispersion liquid 1A was used in place of powder dispersion liquid 11.

[Example 3] Molding 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 (manufactured by Exxon, "ISOPAR H (registered trademark)" ]) and were mixed to obtain a mixture. Next, this mixture was allowed to stand at 25° C. for 2 hours and then extrusion-molded using a paste extruder (cylinder diameter: 60 mm, die diameter: 8 mm) to obtain an extrusion bead. Next, this extruded bead was supplied to a pair of calender rolls having a diameter of 250 mm, rolled at 55° C., processed into a rolled film having a thickness of 1000 μm, further heated to 85° C. and dried to form a sheet. Obtained.
This sheet was biaxially stretched using a biaxial stretching tester under the conditions of a temperature of 300° C., a preheat of 3 minutes and a stretching speed of 2 m/min to obtain a stretched sheet 11. The dimension of the stretched sheet 11 was equal to the dimension of the sheet before stretching, and the stretching ratio was 200% in both the vertical and horizontal directions.

[Example 3-2] Production Example of Stretched Sheet 1A A stretched sheet 1A was obtained in the same manner as in Example 3-1, except that the dry powder 1A was used instead of the dry powder 1.
Each of the stretched sheets was a porous film, and when the open states were compared, it was the stretched sheet 11 and the stretched sheet 1A from the smallest pore size distribution.
Further, when the stretched sheet 11 and a commercially available PTFE sheet were thermocompression bonded (temperature: 300° C., pressure: 1 MPa, time: 60 minutes), both sheets were firmly bonded.

[Example 4] Production Example of Powder Dispersion [Example 4-1] Production Example of Powder Dispersion 21 A dispersion containing 30 parts by mass of the first powder 1, 5 parts by mass of fluoromonool 1 and 65 parts by mass of water. And an aqueous dispersion containing 50% by mass of the second powder 1 were mixed. As a result, the respective powders are dispersed in water, and the powder dispersion 21 containing 50% by mass of PTFE1 and 50% by mass of F polymer 1 with respect to the total of PTFE1 and F polymer 1 (mass of F polymer 1/PTFE1). Mass: 1.0) was obtained.
[Example 1-2] Production Example of Powder Dispersion Liquid 2A A powder dispersion liquid 2A was obtained in the same manner as in Example 4-1 except that the powder 2A was used instead of the first powder 1.

[Example 5] Production example of dry powder [Example 5-1] Production example of dry powder 21 A petri dish filled with the powder dispersion liquid 21 was exposed to an atmosphere of -20°C to freeze the powder dispersion liquid 21. Then, the petri dish was transferred into a vacuum container whose temperature was adjusted to -5°C, and the pressure in the vacuum container was reduced by a vacuum pump to start sublimation of water. The mass of the petri dish was measured over time, and when the mass change rate (g/hr) converged within ±1%, the pressure reduction was terminated and the content of the petri dish was recovered to contain F polymer 1 and PTFE 1. Obtained dry powder 21.
[Example 5-2] Production Example of Dry Powder 2A Dry powder 2A was obtained in the same manner as in Example 5-1 except that powder dispersion liquid 2A was used instead of powder dispersion liquid 21.

[Example 6] Example of coating dry powder [Example 6-1] Example of manufacturing laminated body 21 Using an electrostatic coating machine, the dry powder 21 is supplied from the tank to the coating gun, and is directed from the coating gun to the surface of the copper foil. Then, the dry powder 21 was electrostatically coated. Then, after holding the copper foil on which the dry powder 21 is electrostatically coated for 10 minutes in an atmosphere of 340° C., it is cooled to 25° C., and the copper foil and a coating film formed on the surface of the copper foil (dry powder) 21) was obtained.
The average thickness of the coating film was 60 μm, the difference between the maximum thickness and the minimum thickness was less than 3 μm, and the peel strength between the copper foil and the coating film was 10 N/cm or more. In addition, the coating gun did not clog during electrostatic coating.
[Example 6-2] Manufacturing Example of Layered Product 2A A copper foil and a coating formed on the surface of the copper foil were prepared in the same manner as in Example 6-1 except that the dry powder 2A was used instead of the dry powder 1. A laminated body 2A having a film (baked product of dry powder 2A) was obtained.
The average thickness of the coating film was 60 μm, the difference between the maximum thickness and the minimum thickness was 10 μm, and the peel strength between the copper foil and the coating film was 1 N/cm.

[Example 7] Production example of dry powder [Example 7-1] Production 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 the mixture was placed in an air atmosphere at 325. It heat-processed at 120 degreeC for 120 minute(s), and obtained the mixture. This mixture was gradually cooled to 25° C. and then pulverized with a jet mill to obtain a dry powder 41 having a D50 of 20 μm.
[Example 7-2 (Comparative Example)] Production Example of Dry Powder 42 Dry powder 42 was obtained in the same manner as in Example 7-1 except that the temperature in the heat treatment was changed to 275°C.
Example 7-3 (Comparative Example) Production Example of Dry Powder 43 Dry powder 43 was obtained in the same manner as in Example 7-1 except that the first powder 2 was changed to powder B.

[Example 8] Example of coating dry powder [Example 8-1] Example of manufacturing laminated body 41 Using an electrostatic coating machine, the dry powder 41 was supplied from the tank to the coating gun, and was directed from the coating gun to the surface of the copper foil. Then, the dry powder 41 was electrostatically coated.
Next, the copper foil on which the dry powder 41 was electrostatically coated was held in an atmosphere of 340° C. for 10 minutes and then cooled to 25° C. Thereby, a laminate (average thickness: 60 μm) including the copper foil and the firing layer of the dry powder 41 formed on the surface of the copper foil was obtained.
[Example 8-2 (Comparative Example)] Manufacturing Example of Laminated Body 42 A laminated body 42 was obtained in the same manner as in Example 8-1 except that the dry powder 41 was changed to the dry powder 42.
Example 8-3 (Comparative Example) Manufacturing Example of Laminated Body 43 A laminated body 43 was obtained in the same manner as in Example 8-1, except that the dry powder 41 was changed to the dry powder 43.

<Adhesion evaluation>
The peel strength (N/cm) of the obtained laminate was measured and evaluated according to the following criteria.
[Evaluation criteria]
○: 10 N/cm or more ×: less than 10 N/cm

<Evaluation of coating workability>
The workability in coating work using an electrostatic coating machine was evaluated according to the following criteria.
[Evaluation criteria]
◯: The composite powder was smoothly supplied from the tank to the coating gun, and fibrillation of the composite powder was suppressed during coating, so the coating gun did not clog.
X: The coating gun was easily clogged due to fibrillation of the composite powder during coating, and the discharge was not stable.
The results are summarized in Table 1.

INDUSTRIAL APPLICABILITY The dry powder of the present invention can be used for the production of molded products such as films, impregnated products (prepregs, etc.), laminated plates (metal laminated plates such as resin-coated copper foil), mold release properties, electrical properties, water and oil repellency. It can be used for the production of molded products for applications requiring chemical resistance, weather resistance, heat resistance, slipperiness, wear resistance and the like. Molded articles obtained from the dry powder of the present invention are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, paints, cosmetics, and the like, specifically, wire coating materials. (Covering materials for aircraft wires, data transmission cables, plenum cables, coaxial cables, high frequency cables, flat cables, heat resistant cables, etc.), electrical insulating tapes, oil drilling insulating tapes, printed circuit board materials, separation membranes ( Microfiltration membrane, ultrafiltration membrane, reverse osmosis membrane, ion exchange membrane, dialysis membrane, gas separation membrane, etc.), electrode binder (for lithium secondary battery, fuel cell, etc.), copy roll, furniture, automobile dashboard, Covers for home appliances, sliding members (load bearings, slide shafts, valves, bearings, gears, cams, belt conveyors, food conveyor belts, etc.), tools (shovels, files, saws, saws, etc.), boilers, hoppers, It is useful as a pipe, oven, baking mold, chute, die, toilet bowl, and container covering material.

Claims (12)

1. Dry powder containing a fluoropolymer having a unit based on tetrafluoroethylene and an oxygen-containing polar group, and a tetrafluoroethylene-based polymer.
2. The dry powder according to claim 1, wherein the melting temperature of the fluoropolymer is 140 to 320°C.
3. The dry powder according to claim 1 or 2, wherein the fluoropolymer includes a unit based on a monomer having the oxygen-containing polar group.
4. 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.
5. The tetrafluoroethylene-based polymer is polytetrafluoroethylene, a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether), a copolymer of tetrafluoroethylene and hexafluoropropylene, a copolymer of tetrafluoroethylene and ethylene, or tetrafluoroethylene. The dry powder according to any one of claims 1 to 4, which is a copolymer of and vinylidene fluoride.
6. The dry powder according to any one of claims 1 to 5, wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.
7. The dry powder according to any one of claims 1 to 6, wherein a ratio of the content mass of the fluoropolymer to the content mass of the tetrafluoroethylene-based polymer is 0.4 or less.
8. The method for producing a dry powder according to any one of claims 1 to 7, wherein the powder dispersion includes a first powder of the fluoropolymer, a second powder of the tetrafluoroethylene-based polymer, and water. A method for producing a dry powder, in which the first powder and the second powder are co-coagulated to obtain a wet powder, and the wet powder is dried to obtain the dry powder.
9. The method for producing a dry powder according to any one of claims 1 to 7, wherein the powder dispersion includes a first powder of the fluoropolymer, a second powder of the tetrafluoroethylene-based polymer, and water. A method for producing a dry powder, which comprises freezing and sublimating and removing water to obtain the dry powder.
10. The method for producing a dry powder according to any one of claims 1 to 7, wherein the powder dispersion includes a first powder of the fluoropolymer, a second powder of the tetrafluoroethylene-based polymer, and water. A method for producing a dry powder, wherein the dry powder is obtained by spray drying.
11. The method for producing a dry powder according to any one of claims 1 to 7, wherein the first powder of the fluoropolymer and the second powder of the tetrafluoroethylene-based polymer are mixed and the temperature is higher than 320°C. And a heat treatment to obtain a mixture, and the mixture is pulverized to obtain the dry powder.
12. 12. The volume-based cumulative 50% diameter of the first powder is 0.01 to 75 μm, and the volume-based cumulative 50% diameter of the second powder is 0.01 to 100 μm. The manufacturing method according to item 1.