342 results about "Hexafluoropropylene" patented technology

The invention discloses a lithium ion battery composite diaphragm, a preparation method and a lithium ion battery, and relates to the technical field of lithium ion batteries. The lithium ion battery composite diaphragm comprises a base membrane and a functional coating arranged on the negative electrode side of the base membrane, the functional coating sequentially comprises an ion conducting layer, a thermal barrier layer and a self-repairing layer from the position close to the base film to the position far away from the base film; wherein the base membrane is a polyimide and aramid nanofiber blended electrostatic spinning membrane; the ion conducting layer comprises a compound of a modified fast ion conductor and polyvinylidene fluoride-hexafluoropropylene; the thermal barrier layer comprises a cross-linked network of boron nitride nanosheets and polybenzimidazole; the self-repairing layer comprises polyurethane microspheres loaded with dynamic disulfide bonds. The composite diaphragm provided by the invention can remarkably inhibit a purple area on the surface of a negative electrode, and enhance high-temperature self-protection and interface self-repairing of the lithium ion battery, so that the cycle and safety performance of the lithium ion battery are remarkably improved.

The invention discloses a preparation method and application of a composite PVDF-HFP and polylysine nanofiber diaphragm, and belongs to the technical field of lithium batteries. The composite material is prepared by blending polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and polylysine and then carrying out an electrostatic spinning process. The PVDF-HFP is utilized to provide excellent mechanical strength and chemical stability, rich polar amino functional groups in a polylysine molecular chain are utilized to improve the lyophilic property of the membrane, and anions in an electrolyte are fixed through an intermolecular acting force, so that the transference number of lithium ions is increased, and the lithium ions are induced to be uniformly deposited. The nanofiber membrane combines the characteristics of PVDF-HFP and polylysine, has high porosity, good thermal stability and excellent interface compatibility, can effectively inhibit the growth of lithium dendrites and prevent the diaphragm from being punctured, and can significantly prolong the cycle life and improve the safety performance of the lithium metal battery when being applied to the lithium metal battery.

The invention discloses a PEM proton exchange membrane for water electrolysis and a preparation method thereof, and relates to the technical field of water electrolysis. The proton exchange membrane is composed of five layers of structures including a modified sulfonated composite resin layer, an enhancement layer, a water retention layer, a catalyst layer and an anti-permeation layer, the preparation method comprises the following steps: the modified sulfonated composite resin layer is prepared by dispersing perfluorinated sulfonic acid resin and sulfonated lignin in a solvent, coating and drying; the reinforcing layer is prepared by blending a PTFE (Polytetrafluoroethylene) emulsion, a carbon nanotube and a tetrafluoroethylene-hexafluoropropylene copolymer, and then carrying out casting sintering, plasma treatment and hot press molding; the water retention layer is prepared by adopting an electrostatic spinning technology; the catalyst layer is formed by spraying a precursor solution step by step and drying; the anti-permeation layer is prepared through photoetching-etching array construction, resin coating and fluorosilane modification. The prepared proton exchange membrane has excellent mechanical strength, proton conductivity and stability, and is suitable for the field of PEM water electrolysis.

The invention discloses a fluorinated COF enhanced PVDF-HFP composite gel polymer electrolyte. The fluorinated COF enhanced PVDF-HFP composite gel polymer electrolyte is prepared from the following raw materials: polyvinylidene fluoride-co-hexafluoropropylene, a fluorinated covalent organic framework containing an ether oxygen bond and a carbon-carbon unsaturated double bond, bis (trifluoromethylsulfonyl) imide anion ionic liquid and fluorine-containing imide lithium salt, the fluorinated covalent organic framework containing the ether-oxygen bond and the carbon-carbon unsaturated double bond is prepared by carrying out condensation reaction on a perfluorophenylene-containing module and the ether-oxygen bond-containing aromatic module. According to the electrolyte, PVDF-HFP is used as a polymer matrix, bis (trifluoromethylsulfonyl) imidogen ionic liquid is used as a functional phase and a plasticizer, imide lithium salt is used as a lithium ion source, fluorinated COF containing ether oxygen bonds and olefinic bonds is introduced, and the electrolyte has high ionic conductivity, high lithium ion transference number, excellent mechanical property and interface stability; the method is especially suitable for a high-safety lithium metal battery system.

The invention discloses a low-temperature high-conductivity composite solid-state electrolyte membrane and a preparation method and application thereof, and relates to the technical field of solid-state lithium battery materials, the low-temperature high-conductivity composite solid-state electrolyte membrane comprises: a polymer matrix composed of poly (1, 3-dioxolame) and a polyvinylidene fluoride-hexafluoropropylene copolymer; the ion conduction network is composed of a metal organic framework filler with the surface modified with-SO3Li groups and sulfonic acid lithiated carbon nanotubes arranged in the axial direction of the polymer matrix; a first anti-freezing interface layer and a second anti-freezing interface layer are arranged on the surfaces of the two opposite sides of the polymer matrix, and the first anti-freezing interface layer and the second anti-freezing interface layer are butanedinitrile-glutaronitrile eutectic plastic crystal layers composed of butanedinitrile, glutaronitrile, lithium salt and a nano reinforcing agent respectively. The solid electrolyte is suitable for polar scientific investigation equipment, spacecrafts and other low-temperature environments, and solves the industrial problems of sharp increase of low-temperature grain boundary impedance and interface contact failure of the traditional solid electrolyte.

The application relates to the technical field of batteries, in particular to a composite solid electrolyte membrane and a preparation method and application thereof. The composite solid electrolyte membrane comprises the following layers which are sequentially stacked: a first membrane layer comprising a polymer, a solid electrolyte and a lithium salt; a second membrane layer comprising a polymer, a solid electrolyte and a lithium salt; and a third membrane layer which is an interface layer; wherein the solid electrolyte and the lithium salt content of the second membrane layer are higher than those of the first membrane layer, and the polymer is formed by polymerization of raw materials comprising triacetyl cellulose (TCA) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The composite solid electrolyte membrane has improved high-temperature resistance and good ion transmission performance.

The invention provides a green and efficient production method of hexafluoropropylene oxide, and belongs to the technical field of synthesis of organic fluorine compounds. The method comprises the following steps: carrying out a continuous oxidation reaction on hexafluoropropylene, oxygen and a perfluoro solvent in an immersed supergravity reactor to generate HFPO and byproducts carbonyl fluoride and trifluoroacetyl fluoride, removing the solvent from the reacted liquid, feeding the liquid into an acyl fluoride rectifying tower, separating low-boiling-point acyl fluoride from the tower top, enriching HFPO, unreacted HFP and a small amount of acyl fluoride from the tower bottom, and carrying out a continuous oxidation reaction on the HFPO and the byproducts carbonyl fluoride and trifluoroacetyl fluoride. Converting acyl fluoride into anhydrous trifluoroacetic acid from a high-boiling-point substance at the bottom of the tower through a hydrolysis tower, carrying out alkali washing on the synthesis gas to obtain an HFPO crude product, and further carrying out drying and extractive distillation to obtain an HFPO product; acyl fluoride rectified by an acyl fluoride rectifying tower is directly used for producing PAVE, and long-chain perfluoroacyl fluoride accumulated in a solvent of oxidation reaction is hydrolyzed to synthesize a non-PFOA emulsifier. The method has the advantages of high HFPO selectivity, short reaction time and high safety; the method realizes resource comprehensive utilization of byproducts, and is environment-friendly and economical.

The invention discloses an ultrathin battery diaphragm with high cohesiveness and safety as well as a preparation method and application of the ultrathin battery diaphragm. The battery diaphragm comprises a polyolefin base material and polyvinylidene fluoride coatings arranged on the two sides of the polyolefin base material, wherein each polyvinylidene fluoride coating comprises aluminum oxide particles, a first polyvinylidene fluoride copolymer and a second polyvinylidene fluoride copolymer; the particle size of the aluminum oxide particles is below 0.4 micron; both the first polyvinylidene fluoride copolymer and the second polyvinylidene fluoride copolymer contain vinylidene fluoride and hexafluoropropylene monomer units, and the molar percentage of the hexafluoropropylene monomer unit in the first polyvinylidene fluoride copolymer is lower than that of the hexafluoropropylene monomer unit in the second polyvinylidene fluoride copolymer. The battery diaphragm has ultra-thin thickness, has high binding power with a metal electrode plate, and is high in battery safety when being used for a battery.

The invention discloses a gel electrolyte, a lithium ion battery and a preparation method of the lithium ion battery, and belongs to the technical field of lithium batteries. The invention discloses a gel electrolyte, which comprises a polymer main matrix, an initiator, a lithium salt, an organic solvent, a solid electrolyte and a coalescing agent, and the polymer main matrix comprises poly (vinylidene fluoride-hexafluoropropylene)-polyacrylonitrile-maleic anhydride-ethylene carbonate. The stability of the gel electrolyte is effectively improved.

The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a continuous production process of heptafluoroisobutyryl fluoride. The process is carried out in a tubular reactor, the tubular reactor is divided into a first preheating section, a second reaction section and a third reaction section, a fluorinated molecular sieve catalyst is filled in the second reaction section and the third reaction section, each reaction section is respectively heated to a corresponding preset temperature, carbonyl fluoride and hexafluoropropylene which are mixed and preheated are introduced into the tubular reactor, and a fluorinated molecular sieve catalyst is introduced into the tubular reactor. Enabling the gas to sequentially flow through each section of the tubular reactor, contacting and reacting with the fluorinated molecular sieve catalyst in the second reaction section and the third reaction section, and condensing the gas discharged from the outlet end of the tubular reactor to obtain a heptafluoroisobutyryl fluoride product. According to the process, carbonyl fluoride and hexafluoropropylene are used as gas-phase reaction raw materials, and heptafluoroisobutyryl fluoride is synthesized through a one-step continuous flow rapid reaction. The reaction route is short, the reaction conversion rate and selectivity are high, and industrial large-scale production is easy to realize.

The invention belongs to the technical field of radiation refrigeration, and discloses a modified PVDF and HFP composite porous membrane and a preparation method thereof. The modified PVDF and HFP composite porous membrane comprises a substrate layer, a porous bottom layer and a compact top layer. Wherein the porous bottom layer is prepared from acetone, deionized water, a PVDF-HFP copolymer, a mixed dispersion liquid and a modified nanosheet dispersion liquid; the compact top layer is prepared from acetone, deionized water, a PVDF-HFP (Polyvinylidene Fluoride-Hexafluoropropylene) copolymer, synergistic microspheres and a modified nanosheet dispersion liquid; the mixed dispersion liquid is prepared from acetone, silicon carbide, synergistic microspheres and polyvinylpyrrolidone. The radiation refrigeration capacity, hydrophobicity, dimensional stability and aging resistance of the modified PVDF and HFP composite porous membrane are effectively improved by introducing the modified nanosheet dispersion liquid and the synergistic microspheres. Therefore, the method has a wider application prospect.

The invention provides an MXene-based binder, a tungsten-based delay powder and a preparation method, and the preparation method of the MXene-based binder specifically comprises the following steps: mixing a vinyl chloride-vinyl acetate resin solution, a polyvinylidene fluoride-hexafluoropropylene solution and an MXene suspension to obtain a mixed solution; and adding a plasticizer into the mixed solution, stirring, drying, freezing and crushing to obtain the Mxene-based binder. The preparation method of the binder system is simple, large-scale production is facilitated, and the binder system is stable in combustion, high in combustion efficiency, good in mechanical property and low in gas yield when applied to the tungsten delay powder.

The invention discloses a perfluoropolyether-based polymer solid electrolyte film regulated and controlled by a mixed solvent as well as a preparation method and application of the perfluoropolyether-based polymer solid electrolyte film, and belongs to the field of organic polymer solid electrolyte preparation. Reacting under the action of an initiator and an RAFT (reversible addition-fragmentation chain transfer) reagent to obtain a perfluoropolyether-based copolymer; the method comprises the following steps: adding a perfluoropolyether-based copolymer into a polyvinylidene fluoride-hexafluoropropylene copolymer solution in which lithium salt is dissolved, the mass of the polyvinylidene fluoride-hexafluoropropylene copolymer accounts for 10%-30% of the mass of the polyvinylidene fluoride-hexafluoropropylene copolymer, the mass of the N, N '-dimethylformamide, the mass of the trifluorotoluene and the mass of the perfluoropolyether-based copolymer account for 10%-30% of the mass of the polyvinylidene fluoride-hexafluoropropylene copolymer, and the perfluoropolyether-based polymer solid-state electrolyte film is obtained by uniformly mixing and then preparing a film. And the comprehensive performance of the composite solid electrolyte serving as the film is improved.

The invention relates to a polyurethane-based composite solid polymer electrolyte film and a preparation method and application thereof, and belongs to the field of organic polymer solid electrolyte preparation. Polyethylene glycol-polypropylene glycol triblock copolymer and hydroxyl-terminated polybutadiene are used as soft segments, isophorone diisocyanate is used as a hard segment, and under the action of a catalyst, the polyurethane-based composite solid polymer electrolyte film is prepared. A chain extender containing disulfide bonds is utilized, and a polyurethane elastomer is prepared through gradual addition polymerization reaction; a polyurethane elastomer and a mixed solution of a lithium salt and a polyvinylidene fluoride-hexafluoropropylene copolymer are uniformly mixed, the polyurethane elastomer accounts for 10%-30% of the mass of the polyvinylidene fluoride-hexafluoropropylene copolymer, a precursor solution is obtained, the precursor solution is prepared into a film, and the polyurethane-based composite solid polymer electrolyte film is obtained. The polymer solid electrolyte membrane with excellent mechanical property and excellent lithium ion conductivity is constructed, and the development requirement of a high-performance lithium metal battery is met.

The invention belongs to the technical field of material physics, and particularly relates to a triboelectroluminescence composite material, a preparation method thereof and a triboelectroluminescence tactile device. The triboelectric electroluminescent composite material is formed by compounding a polymer matrix, a triboelectric reinforcing filler and fluorescent powder, the frictional electricity reinforcing filler is polytetrafluoroethylene; the fluorescent powder is ZnS: Cu; and the polymer matrix is polyvinylidene fluoride-hexafluoropropylene. The triboelectroluminescent composite material is used as a luminescent layer and a triboelectrification layer, and the triboelectroluminescent tactile device constructed by the triboelectroluminescent composite material and a friction material shows an ultra-low pressure detection limit of 0.42 Pa; and along with the increase of the pressure intensity, the output optical signal and electric signal are stronger. The strongest luminous intensity of the triboluminescence tactile device is 1.25 times of the indoor light intensity, and the triboluminescence tactile device can obviously emit light in outdoor sunlight.

The invention discloses a coating diaphragm and a preparation method thereof, the coating diaphragm comprises a base film, a first coating and a second coating, the first coating and the second coating are respectively located on two sides of the base film; the first coating comprises sodium carboxymethyl cellulose, a metal organic framework, a modified solid electrolyte and a first pressure-sensitive adhesive, and the modified solid electrolyte is obtained by modifying a solid electrolyte with silicon resin; and the second coating comprises sodium carboxymethyl cellulose, a polyvinylidene fluoride-hexafluoropropylene copolymer, an emulsion type binder and a second pressure-sensitive binder. The solid electrolyte has a rigid framework to provide a rapid conduction channel, and the metal organic framework has a high specific surface area and can cooperate with the solid electrolyte to construct a three-dimensional network, so that the stable performance of the coating diaphragm is guaranteed.

The invention provides a lithium metal negative electrode protection layer, a preparation method and application thereof, and a lithium metal battery, and relates to the technical field of lithium metal batteries, the protection layer is formed on the surface of a metal lithium foil, and comprises a polymer and an inorganic substance; the polymer comprises polyvinylidene fluoride-hexafluoropropylene; the inorganic substance includes lithium phosphate. The components of the protective layer cooperate with each other, so that lithium dendrites can be physically inhibited, the first discharge specific capacity, the first coulombic efficiency and the cycle performance can be effectively improved, gas can be actively consumed, and the cycle stability and the safety performance of the lithium metal battery can be cooperatively improved from multiple dimensions; the technical problems that an existing protective layer cannot actively eliminate gas, the lithium dendrite inhibiting effect is poor, and the interface stability is poor are solved.

The invention discloses a multi-component composite negative electrode material of a sodium-ion battery and a preparation method of the multi-component composite negative electrode material, and relates to the technical field of sodium-ion batteries. The preparation method of the negative electrode material comprises the steps of hard carbon pretreatment, in-situ deposition of Sn-Sb nano-particles, preparation of a hard carbon coated Sn-Sb-carbon nanotube compound and preparation of the negative electrode material. The adopted raw materials comprise hard carbon, SnCl2. 2H2O, SbCl3, a NaBH4 solution, a single-walled carbon nanotube, a polyvinylidene fluoride-hexafluoropropylene copolymer, an emulsifier, a defoaming agent, nano aluminum oxide and a copper foil current collector. The battery negative electrode material prepared by the invention has excellent mechanical properties, and can effectively improve the cycling stability and wide temperature range suitability of the sodium ion battery.

The present invention relates to the field of fluororubber synthesis, and disclosed is a preparation method for high-fluorine-content low-compression-set peroxide-cured fluororubber. In the method, vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene are used as mixed monomers to carry out polymerization reaction, wherein during the polymerization reaction, a cure-site monomer is added. By adjusting the composition ratio of the mixed monomers and uniformly and continuously adding the cure-site monomer, peroxide-cured fluororubber having high fluorine content, resistance to new energy battery media, and low compression set is prepared. The peroxide-cured fluororubber prepared by the method provided in the present invention has a fluorine content stably at 70-71%, a compression set stably less than or equal to 20%, a tensile strength of approximately 22 MPa, and an elongation at break greater than 180%. That is, the problem of relatively high compression set of peroxide-cured fluororubber (particularly high-fluorine-content peroxide-cured fluororubber) in new energy battery applications is effectively solved.

The invention discloses a device and a method for treating hexafluoropropylene coarse pyrolysis gas in a hexafluoropropylene preparation process, a quench cooler (1) is sequentially communicated with a carbon powder filter (2) and an external shell I (6), a spiral guide plate I (7) in the external shell I (6) is communicated with the external shell I (6), the spiral guide plate I (7) is communicated with a deacidification treatment unit (28), and the deacidification treatment unit (28) is communicated with a deacidification treatment unit (28). The deacidification treatment unit (28) is communicated with the gas outlet I (9) through a drainage pipe I (10), the dry-type deacidification device (3) is communicated with the external shell II (11), the spiral guide plate II (13) is communicated with the external shell II (11), the spiral guide plate II (13) is communicated with the dehydration treatment unit (29), the dehydration treatment unit (29) is communicated with the gas outlet II (24) through a drainage pipe II (14), and the dry-type deacidification device (3) is communicated with the gas outlet II (24) through a drainage pipe II (14). And the outer shell II (11) is communicated with the film coating powder remover (5). According to the invention, the hexafluoropropylene crude pyrolysis gas is effectively treated and collected.

The invention relates to the technical field of batteries, in particular to a composite solid electrolyte membrane and a preparation method and application thereof. The composite solid electrolyte membrane comprises the following layers which are stacked in sequence: a first membrane layer which comprises a polymer, a solid electrolyte and a lithium salt; the second film layer comprises a polymer, a solid electrolyte and a lithium salt; the third film layer is an interface layer; wherein the solid electrolyte content and the lithium salt content of the second film layer are both higher than the solid electrolyte content and the lithium salt content of the first film layer, and the polymer is formed by polymerizing raw materials including cellulose triacetate (TCA) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The composite solid electrolyte membrane has improved high temperature resistance and good ion transmission performance.

The application discloses a super-capacitive off-electric flexible pressure sensor and a preparation method thereof. The super-capacitive off-electric flexible pressure sensor comprises a first electrode plate, a second electrode plate and a flexible dielectric layer. The first electrode plate and the second electrode plate are oppositely arranged. The first electrode plate comprises a first flexible substrate and a first electrode layer arranged below the first flexible substrate. The second electrode plate comprises a second flexible substrate and a second electrode layer arranged above the second flexible substrate. The flexible dielectric layer is arranged between the first electrode layer and the second electrode layer. The flexible dielectric layer is a bucky gel composite material obtained by embedding an ionic liquid into a physical cross-linking network combined with acidified carbon nanotubes and polyvinylidene fluoride-hexafluoropropylene copolymer. The bucky gel based on a micro-ridge structure is used as the flexible dielectric layer, and the flexible electrode is pressed and bonded, so that the super-capacitive off-electric flexible pressure sensor is prepared.

The invention discloses a metal oxide modified fiber material as well as a preparation method and application thereof. The preparation method comprises the following steps: stirring and dissolving tetraethoxysilane, tungsten chloride, ethanol and hydrochloric acid to form a uniform solution; mixing and dissolving polyvinylpyrrolidone, N, N-dimethylformamide and dimethyl sulfoxide to form another solution; mixing the solutions to prepare a spinning solution, and performing electrostatic spinning to obtain fibers; and dissolving a polyvinylidene fluoride-hexafluoropropylene copolymer and lithium bis (fluorosulfonyl) imide in N-methyl pyrrolidone to form a homogeneous solution, adding the fibers, stirring and mixing, casting to form a film, blade-coating the film to a predetermined thickness, and performing vacuum drying to obtain the target composite electrolyte. The method comprises the following steps: preparing a silicon dioxide nanofiber loaded tungsten oxide nanowire with a high length-diameter ratio through electrostatic spinning, and compounding the silicon dioxide nanofiber loaded tungsten oxide nanowire with a polyvinylidene fluoride-hexafluoropropylene copolymer matrix. The method is simple, convenient, efficient and low in cost, the prepared solid electrolyte is high in stability, the long cycle performance of the battery is remarkably improved, and an important basis is provided for optimizing polyvinylidene fluoride-hexafluoropropylene copolymer based electrolyte and developing a high-performance all-solid-state lithium ion battery.

The present invention provides a hexafluoropropene dimer-containing composition as a novel mixture. Disclosed is a composition which contains hexafluoropropene dimers represented by C6F12, wherein: at least one of the hexafluoropropene dimers represented by C6F12 is a compound represented by formula (I); and the abundance ratio E / (E + Z) of the E-form among the E-form and the Z-form of the compound is more than 0.5.

There is provided an inorganic solid electrolyte-containing composition containing an inorganic solid electrolyte, a polymer binder, and a dispersion medium, in which the polymer binder includes a polymer binder consisting of a fluorine-based copolymer which contains a vinylidene fluoride constitutional component and a hexafluoropropylene constitutional component of 21% to 65% by mole and in which a tensile fracture strain is 500% or more, and the adsorption rate of this polymer binder with respect to the inorganic solid electrolyte is less than 60%. There are also provided a sheet for an all-solid state secondary battery and an all-solid state secondary battery, in which this inorganic solid electrolyte-containing composition is used, and manufacturing methods for a sheet for an all-solid state secondary battery, and an all-solid state secondary battery.

Provided is a fluorine-containing copolymer which is a fluorine-containing copolymer containing tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein the content of the hexafluoropropylene units is 7.0 to 12.0 mass% relative to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 1.5 to 2.9 mass% relative to the total monomer units, and the melt flow rate at 372°C is 40 to 60 g / 10 minutes.

The invention discloses an environment-friendly refrigeration composition for compression refrigeration, the ODP value of the environment-friendly refrigeration composition is 0, the GWP is less than 150, and the refrigeration composition comprises hexafluoropropylene serving as a first component and accounting for 30-50% of the total mass of the refrigeration composition; the trifluoroethylene is used as a second component and accounts for 30-50% of the total mass of the refrigeration composition; the third component is selected from at least one of cyclopropane, difluoromethane or trifluoroacetyl fluoride, and the mass of the third component accounts for 10-30% of the total mass of the refrigeration composition. The refrigeration composition can replace R410A to be used for a household air conditioner or a commercial air conditioner system, parts of the air conditioner system do not need to be replaced, the environmental performance is far better than that of the R410A, and the cycle performance is equivalent to or slightly better than that of the R410A.

To provide an etching method using hexafluoropropene.SOLUTION: Etching gas contains at least one kind of component selected from the group consisting of hexafluoropropene and hexafluorocyclopropane, and a dimer and / or a trimer derived from hexafluoropropene and hexafluorocyclopropane. With respect to the total amount of the etching gas, (1) 95 vol.% to 99.99999 vol.% of the hexafluoropropene is contained, and (2) 1 vol.ppm to 1,000 vol.ppm of at least one kind of component selected from the group consisting of hexafluoropropene and hexafluorocyclopropane, and a dimer and / or a trimer derived from hexafluoropropene and hexafluorocyclopropane is contained.SELECTED DRAWING: None