Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08L27/18—Homopolymers or copolymers or tetrafluoroethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/003—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor characterised by the choice of material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/006—Pressing and sintering powders, granules or fibres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/005—Processes for mixing polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
  • B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
  • B29K2027/18—PTFE, i.e. polytetrafluoroethylene, e.g. ePTFE, i.e. expanded polytetrafluoroethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/25—Solid
  • B29K2105/251—Particles, powder or granules
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/26—Scrap or recycled material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene

Definitions

• the present invention relates to a method for producing a fluororesin composition.
• Polytetrafluoroethylene resin (molding powder) obtained by suspension polymerization of tetrafluoroethylene (TFE) is compression molded and then sintered to form a molded body.
• the molded body obtained by sintering is processed into a molded product of a desired shape by cutting or the like.
• tetrafluoroethylene resin sintered PTFE
• cutting waste generated during processing is hard and does not hold together even when compressed after crushing, making it impossible to mold. For this reason, it has been difficult to reuse it.
• Patent Document 1 describes how, when sintered PTFE powder is mixed with a PTFE dispersion (a dispersion of unsintered PTFE) obtained by emulsion polymerization of TFE, compression molded, and sintered to produce a molded body, the porosity after sintering decreases and the tensile strength after sintering increases as the mixing ratio of unsintered PTFE increases. For example, it describes an example in which the porosity after sintering becomes 0% when the mixing ratio of unsintered PTFE is 100%.
• a PTFE dispersion a dispersion of unsintered PTFE obtained by emulsion polymerization of TFE, compression molded, and sintered to produce a molded body
• the inventors of the present application manufactured sintered PTFE molded products using the powder obtained by crushing cutting chips of sintered PTFE according to the method described in Patent Document 1, and confirmed that the chemical resistance was inferior to that of molded products manufactured using unsintered PTFE.
• the objective of the present invention is to provide a method for producing a fluororesin composition that can produce molded articles with high chemical resistance even when using a fluororesin that has a thermal history of being heated above its melting point.
• a method for producing a fluororesin composition comprising a first fluororesin having a thermal history of being heated to or above its melting point, and a second fluororesin having no thermal history of being heated to or above its melting point, wherein the first fluororesin and the second fluororesin are non-melt-formable fluororesins, the method comprising washing a crushed material comprising the first fluororesin, and mixing the washed crushed material with the second fluororesin, wherein the thermal weight loss rate calculated by the following formula I when the temperature of the washed crushed material is raised to 30 to 280°C at a rate of 10°C/min is 3% or less.
• Thermogravimetric reduction rate (W B1 - W A1 )/W B1 ⁇ 100 Formula I
• W B1 is the mass of the crushed material at 30°C
• W A1 is the mass of the crushed material at 280°C.
• the present invention provides a method for producing a fluororesin composition that can produce molded articles with high chemical resistance even when using a fluororesin that has a thermal history of being heated above its melting point.
• unit based on a monomer is a general term for an atomic group formed directly by polymerization of one monomer molecule and an atomic group obtained by chemically converting a part of the atomic group.
• a unit based on a monomer is also simply referred to as a monomer unit.
• “Monomer” means a compound that has a polymerizable carbon-carbon double bond.
• “Melting point” means the temperature corresponding to the maximum of the melting peak as measured by differential scanning calorimetry (DSC). The use of "to” indicating a range of numerical values means that the numerical values before and after it are included as the lower limit and upper limit.
• average particle size refers to the 50% integrated value (median diameter, D50) in the number-based particle size distribution determined using a laser diffraction/scattering particle size distribution analyzer (for example, LA-920 measuring instrument manufactured by Horiba, Ltd.).
• melt-formable it is meant that the material exhibits melt flowability.
• Exhibiting melt fluidity means that there exists a temperature at which the melt flow rate is 0.1 to 1000 g/10 min under a load of 49 N at a temperature at least 20° C. higher than the melting point of the resin.
• Melt flow rate means the melt mass flow rate (MFR) as defined in JIS K 7210:1999 (ISO 1133:1997).
• non-melt moldable means that the material does not exhibit the melt flowability.
• Standard specific gravity (hereinafter also referred to as "SSG”) is a value that is an index of average molecular weight, and the larger this value is, the smaller the molecular weight is. It can be measured in accordance with ASTM D1457-91a, D4895-91a.
• the method for producing a fluororesin composition of this embodiment is a method for producing a fluororesin composition comprising a first fluororesin (hereinafter also referred to as "fluororesin 1") having a thermal history of being heated to or above its melting point, and a second fluororesin (hereinafter also referred to as "fluororesin 2”) having no thermal history of being heated to or above its melting point.
• Fluororesin 1 and fluororesin 2 are non-melt-formable fluororesins.
• the method for producing a fluororesin composition of this embodiment includes washing a crushed material containing fluororesin 1, and mixing the washed crushed material with fluororesin 2.
• the thermal weight loss rate calculated by the following formula I when the washed crushed material is heated to 30 to 280°C at a rate of 10°C/min is 3% or less,
• Thermogravimetric reduction rate (W B1 - W A1 )/W B1 ⁇ 100 Formula I
• W B1 is the mass of the crushed material at 30°C
• W A1 is the mass of the crushed material at 280°C.
• Both fluororesin 1 and fluororesin 2 are non-melt-formable fluororesins.
• the fluororesin 1 and the fluororesin 2 may be the same as or different from each other.
• the fluororesin 1 and the fluororesin 2 may each independently be one type of fluororesin or two or more types of fluororesin may be used in combination. When two or more types of fluororesin are used in combination, it is sufficient that the mixture of the two or more types of fluororesin is non-melt moldable.
• TFE units polymers having tetrafluoroethylene units
• examples thereof include polytetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, tetrafluoroethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-ethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.
• PTFE polytetrafluoroethylene
• tetrafluoroethylene-ethylene copolymer tetrafluoroethylene-hexafluoropropylene copolymer
• tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer
• fluororesin 1 and fluororesin 2 are each independently PTFE.
• the content of TFE units in PTFE relative to the total mass of the fluororesin is preferably 99 mass% or more.
• the content of TFE units in PTFE relative to the total mass of the fluororesin is more preferably 99.5 mass% or more, and may be 100 mass%.
• Monomer units other than TFE units include the above-mentioned ethylene units, hexafluoropropylene units, perfluoro(alkyl vinyl ether) units, chlorotrifluoroethylene units, vinylidene fluoride units, as well as monomer units based on perfluoro(2,2-dimethyl-1,3-dioxole), perfluoro(4-methoxy-1,3-dioxole), perfluoroalkylethylene, etc.
• the monomer units other than TFE units may be of one type or of two or more types. By including monomer units other than TFE units, crystallization of PTFE is suppressed to some extent, and tensile strength, tensile elongation, resistance to dielectric breakdown, creep resistance, etc. are improved.
• the fluororesin 1 has a thermal history of being heated to a melting point or higher at least once.
• the fluororesin 1 can be obtained by pulverizing cuttings generated when processing a primary molded body produced by heating to a melting point or higher into a secondary molded body such as an industrial part having a desired shape, or an unnecessary secondary molded body.
• the pulverization can be performed using a pulverizer or the like. After coarse pulverization, the material may be pulverized into fine particles.
• the heating can be exemplified by heating by firing required for producing a molded body.
• the melting point of the fluororesin 1 becomes lower than the melting point of the fluororesin 1 before being heated to or above its melting point.
• DSC differential scanning calorimetry
• the melting point of the fluororesin 1 before being heated to the melting point or higher is preferably 360° C. or lower, more preferably 355° C. or lower, and even more preferably 350° C. or lower.
• the melting point is preferably 100 to 360° C., more preferably 100 to 355° C., and even more preferably 150 to 350° C. When the melting point is within the above range, the mechanical strength of the obtained molded article tends to be improved.
• the melting point of the fluororesin 1 is preferably 335° C. or lower, and more preferably 330° C. or lower.
• the lower limit of the melting point is not particularly limited, but is preferably 100° C. or higher, and more preferably 150° C. or higher.
• the melting point is preferably 100 to 335° C., and more preferably 150 to 330° C. When the melting point is within the above range, the mechanical strength of the obtained molded article tends to be improved.
• the bulk density of fluororesin 1 is preferably 100 g/L or more, more preferably 105 g/L or more, and even more preferably 110 g/L or more.
• the bulk density is equal to or more than the lower limit, less air is carried in during the production of the molded body, which results in excellent deaeration properties and good fusion between powder particles. Furthermore, voids are less likely to remain in the resulting molded body, and the uniformity of the molded body is also likely to be improved.
• the average particle size of the fluororesin 1 is preferably from 1 to 500 ⁇ m, more preferably from 5 to 300 ⁇ m, and even more preferably from 5 to 100 ⁇ m. When the average particle size of the fluororesin 1 is within the above range, the uniformity of the obtained molded article is improved.
• the fluororesin 1 may be, for example, crushed pieces of a molded product obtained by molding a molding material containing PTFE obtained by suspension polymerization using a method including a step of heating the material to the melting point or higher.
• the PTFE obtained by suspension polymerization has a very high melt viscosity, and is non-melt moldable, which means that it cannot be molded by the general molding method of thermoplastic resins, such as extrusion molding, injection molding, etc. Therefore, when molding the PTFE produced by suspension polymerization (hereinafter also referred to as "molding powder"), the molding powder is filled into a mold, compression molded, and then fired.
• the molding powder is molded by first filling the molding powder into a mold at room temperature, compressing it to form a preform, and then heating it to the melting point of PTFE or higher to sinter it to form a primary molded body.
• the molding powder may be granulated as necessary and used as a granulated product.
• inorganic fillers and other optional components may be mixed during granulation.
• the primary molded body is then machined, such as by cutting, to produce a secondary molded body of a desired shape. Examples of secondary molded bodies include industrial components such as gaskets, linings, and insulating films, and square tanks that are exposed to strong acids and strong alkalis in the semiconductor industry. Cuttings, scraps, etc.
• cuttings, etc. generated when cutting a primary molded body into a secondary molded body, powder obtained by crushing the cuttings, powder obtained by crushing unnecessary secondary molded bodies, etc. can be used as the fluororesin 1.
• the cuttings, etc. and the powder are collectively referred to as "crushed material.”
• the secondary molded body or the cuttings, etc. can be crushed by a crusher or the like. After coarse crushing, they may be finely ground. The volume of each crushed material is, for example, 50 cm3 or less.
• the method for producing a fluororesin composition according to this embodiment includes washing the crushed material containing fluororesin 1.
• the crushed material is essentially composed of only fluororesin 1.
• trace amounts of impurities such as oil stains and dirt may adhere to the fluororesin 1.
• the crushed material is composed of fluororesin 1 and the trace amounts of impurities.
• the thermal weight loss rate of the crushed material before washing calculated by the above formula I (hereinafter, sometimes referred to as "thermal weight loss rate before washing") is preferably 3 to 20%, more preferably 3 to 15%, and even more preferably 3 to 10%.
• thermal weight loss rate before washing is equal to or higher than the lower limit of the above range, the effects of the present invention are easily obtained.
• thermal weight loss rate before washing is equal to or lower than the upper limit of the above range, the chemical resistance of the obtained molded article is easily improved.
• the thermal weight loss rate of the crushed material after washing calculated by the above formula I (hereinafter, sometimes referred to as "thermal weight loss rate after washing") is 3% or less, preferably 2% or less, and more preferably 1.5% or less.
• the lower limit of the thermal weight loss rate after washing is not particularly limited, but may be 0%. That is, the thermal weight loss rate after washing is preferably 0 to 3%, preferably 0 to 2%, and more preferably 0 to 1.5%. When the thermal weight loss rate after washing is equal to or less than the upper limit, the chemical resistance of the resulting molded article is likely to be improved. From the viewpoint of more reliably obtaining the effects of the present invention, the thermal weight loss rate after washing is most preferably 0%.
• the cleaning liquid for washing the crushed material examples include water, organic solvents, surfactants, etc. Also, a cleaning liquid such as an aqueous solution containing two or more of these may be used.
• the amount of cleaning liquid used is preferably 10 to 5,000 parts by mass, more preferably 50 to 4,000 parts by mass, and even more preferably 100 to 3,000 parts by mass, per 100 parts by mass of the crushed material. Washing may be performed by method 1, in which the crushed material is immersed in the cleaning liquid and left to stand, method 2, in which the crushed material is stirred, or method 3, in which the cleaning liquid is poured over the crushed material.
• the immersion time is preferably more than 0 hours and not more than 100 hours, more preferably more than 0 hours and not more than 80 hours, and even more preferably more than 0 hours and not more than 60 hours.
• the temperature of the cleaning liquid is preferably 0 to 200°C, and more preferably 10 to 150°C.
• washing is preferably performed 1 to 30 times, more preferably 1 to 25 times, and even more preferably 2 to 20 times.
• washing in method 3 is preferably performed multiple times.
• the crushed material to be washed may be crushed material such as cutting chips that are generated directly during the production of the secondary molded body, or crushed material in powder form obtained by pulverizing the secondary molded body or cutting chips. From the viewpoint of operability, crushed material such as cutting chips that are generated directly during the production of the secondary molded body is preferred.
• the fluororesin 2 does not have a thermal history of being heated to a temperature equal to or higher than its melting point.
• the melting point of the fluororesin 2 is preferably 360° C. or less, more preferably 355° C. or less, and even more preferably 350° C. or less.
• the lower limit of the melting point is not particularly limited, but is preferably 100° C. or more, and more preferably 150° C. or more.
• the melting point is preferably 100 to 360° C., more preferably 100 to 350° C., and even more preferably 150 to 350° C. When the melting point is within the above range, the mechanical strength of the obtained molded article tends to be improved.
• the fluororesin 2 may be, for example, a fluororesin produced by emulsion polymerization.
• the emulsion polymerization method is a polymerization method in which a monomer is polymerized in an aqueous medium containing water to obtain a dispersion containing particles of the fluororesin 2.
• emulsion polymerization is performed by a method in which a reaction liquid containing water, a polymerization initiator, and a surfactant is polymerized in the reaction liquid while the reaction liquid is stirred.
• the content of the nonionic surfactant is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.1 part by mass or less, per 100 parts by mass of the fluororesin in the dispersion. Examples of nonionic surfactants will be described later.
• the content of fluororesin 2 in the dispersion is preferably 5 to 40 mass%, more preferably 7 to 35 mass%, and even more preferably 10 to 30 mass%.
• the average particle size of the fluororesin 2 contained in the dispersion is preferably 0.05 to 0.5 ⁇ m, more preferably 0.08 to 0.45 ⁇ m, and even more preferably 0.10 to 0.35 ⁇ m. When the average particle size is within the above range, the emulsion stability is excellent.
• the fluororesin 2 preferably contains PTFE obtained by emulsion polymerization.
• a TFE monomer is homopolymerized in the reaction liquid, or a TFE monomer is copolymerized with a monomer other than TFE monomer in the reaction liquid to obtain a dispersion liquid in which PTFE particles are dispersed in a dispersion medium.
• the pressure is preferably 0.5 to 3.0 MPa
• the TFE monomer is emulsion-polymerized for preferably 1 to 20 hours to obtain a dispersion.
• the nonionic surfactant may also be added.
• a dispersion may be obtained without using a fluorine-based surfactant by the methods described in WO 2021/085470, WO 2022/181662, etc.
• the amount of the anionic fluorine-containing emulsifier used in the emulsion polymerization step of TFE monomer is preferably 0.15 to 2.0 parts by mass, more preferably 0.2 to 1.0 part by mass, and even more preferably 0.2 to 0.5 part by mass, per 100 parts by mass of the PTFE produced.
• paraffin wax As the stabilizing aid, paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. are preferable, and paraffin wax is more preferable.
• the stabilizing aid may be used alone or in combination of two or more kinds.
• the paraffin wax may be liquid, semi-solid or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms.
• the melting point of the paraffin wax is preferably 40 to 65° C., more preferably 50 to 65° C.
• the amount of the stabilizing aid used is preferably 0.1 to 12 parts by mass, more preferably 0.1 to 8 parts by mass, per 100 parts by mass of the aqueous medium used.
• a water-soluble radical initiator or a water-soluble redox catalyst is preferably used.
• a persulfate such as ammonium persulfate or potassium persulfate; or a water-soluble organic peroxide such as disuccinic acid peroxide, bisglutaric acid peroxide, or tert-butyl hydroperoxide; is preferable.
• the polymerization initiator may be used alone or in combination of two or more. An oil-soluble initiator can also be used.
• disuccinic acid peroxide is more preferable.
• the amount of the polymerization initiator used is preferably 0.01 to 0.20 parts by mass, and more preferably 0.01 to 0.15 parts by mass, per 100 parts by mass of the PTFE to be produced.
• the standard specific gravity (SSG) of the PTFE resin contained in the dispersion is an index of the average molecular weight of PTFE, and it can be conceptually classified as high molecular weight PTFE when the SSG is 2.14 or more and less than 2.22, and low molecular weight PTFE when the SSG is 2.22 to 2.4. Since the physical properties of PTFE decrease when the molecular weight is low, the SSG is preferably 2.14 or more and less than 2.22, and more preferably 2.14 to 2.21.
• anionic fluorine-containing emulsifier examples include fluorine-containing emulsifiers represented by general formula (1) (hereinafter, also referred to as "fluorine-containing emulsifier (1)").
• General formula (1) XCF 2 CF 2 (O) m CF 2 CF 2 OCF 2 COOA (In the formula, X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4 , and m is 0 or 1.)
• the fluorine-containing emulsifier (1) is preferred because of its excellent polymerization stabilizing effect on the PTFE particles.
• the above X is preferably a fluorine atom.
• the above m is preferably 1 in view of good polymerization stability and good mechanical stability of the dispersion.
• Specific examples of A include H, Li, Na, K, and NH4.
• NH4 is preferred in view of good solubility of the fluorine-containing emulsifier (1) in water and of metal ion components that are unlikely to remain as impurities .
• Particularly preferred examples of the fluorine - containing emulsifier ( 1) are CF3CF2CF2CF2OCF2COONH4 and C2F5OCF2CF2OCF2COONH4 ( hereinafter referred to as EEA ), with EEA being more preferred.
• the fluorine-containing emulsifier (1) can be produced by fluorinating the corresponding ester of a non-fluorine-containing carboxylic acid or a partially fluorinated carboxylic acid by a known fluorination method such as a liquid phase fluorination method in which the ester is reacted with fluorine in a liquid phase, a fluorination method using cobalt fluoride, or an electrochemical fluorination method, hydrolyzing the ester bond of the resulting fluorinated ester, purifying it, and neutralizing it with ammonia.
• a known fluorination method such as a liquid phase fluorination method in which the ester is reacted with fluorine in a liquid phase, a fluorination method using cobalt fluoride, or an electrochemical fluorination method, hydrolyzing the ester bond of the resulting fluorinated ester, purifying it, and neutralizing it with ammonia.
• Nonionic fluorine-containing emulsifier Nonionic fluorine-containing emulsifier
• nonionic surfactant (2) a nonionic surfactant represented by general formula (2)
• nonionic surfactant (3) a nonionic surfactant represented by general formula (3)
• R 1 -ODH (In the formula, R1 is an alkyl group having 8 to 18 carbon atoms, O is an oxygen atom, and D is a polyoxyalkylene chain consisting of 5 to 20 oxyethylene groups and 1 to 2 oxypropylene groups.)
• R 2 -OEG (In the formula, R2 is an alkyl group having 6 to 18 carbon atoms, O is an oxygen atom, E is a polyoxyalkylene chain consisting of 1 to 3 oxybutylene groups and 5 to 20 oxyethylene groups, and G is a hydrogen atom or a methyl group.)
• the nonionic surfactants may be used alone or in combination of two or more kinds.
• the nonionic surfactant contained in the dispersion is preferably one or more selected from the group consisting of nonionic surfactant (2) and nonionic surfactant (3), and two or more may be used in combination.
• Nonionic surfactant (2) and nonionic surfactant (3) may be combined.
• Nonionic surfactants are mixtures of multiple molecules with a certain chain length distribution and a mixture of isomers, and the chain length of the polyoxyalkylene chain represents the average chain length of multiple molecules.
• the number of oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain is the average value.
• the average number of oxyalkylene groups in each nonionic surfactant should be within the above-mentioned range.
• each numerical value is not limited to an integer.
• the number of carbon atoms in the alkyl group represented by R1 is preferably in the range of 8 to 18, more preferably 10 to 16.
• the number of carbon atoms in R1 is equal to or greater than the lower limit of the above range, the surface tension of the dispersion is likely to be low and the wettability is likely to be increased.
• the number of carbon atoms is equal to or less than the upper limit, the storage stability of the dispersion is excellent.
• the alkyl group which is a hydrophobic group, has a branched structure in which it branches in the middle, it is preferable because it is easier to increase the wettability of the dispersion.
• the alkyl group having a branched structure is preferably an alkyl group having a branch in the range from the carbon atom at the base of the alkyl group to the fifth carbon atom, and more preferably an alkyl group having a branch in the range from the carbon atom at the base of the alkyl group to the third carbon atom.
• the branched carbon atom may be a secondary carbon atom or a tertiary carbon atom, and a secondary carbon atom is preferred.
• Examples of the alkyl group having a branched structure include C10H21CH ( CH3 ) CH2- , C9H19CH ( C3H7 )- , and C6H13CH ( C6H13 ) -.
• the hydrophilic group D is a polyoxyalkylene chain consisting of 5 to 20 oxyethylene groups and 1 to 2 oxypropylene groups.
• the polyoxyalkylene chain consists of 7 to 12 oxyethylene groups and 1 to 2 oxypropylene groups, the properties of the dispersion become favorable.
• D contains an oxypropylene group, the defoaming property is likely to be improved.
• the number of oxypropylene groups is 2 or less, the surface tension is low, the wettability is easily increased, and repellency during recoating is unlikely to occur, which is preferable.
• the oxypropylene group may be present between the polyoxyethylene groups, or may be bonded to the polyoxyethylene chain end.
• the defoaming property is easily improved.
• the defoaming property is more easily improved.
• the average number of oxyethylene groups in one molecule is preferably 5 to 20, and more preferably 7 to 12.
• the average number of oxyethylene groups in one molecule is equal to or more than the lower limit of the above range, good storage stability is likely to be obtained.
• the average number of oxyethylene groups in one molecule is equal to or less than the upper limit of the above range, good wettability is likely to be obtained.
• nonionic surfactant (2) commercially available nonionic surfactants having average molecular structures such as C13H27O ( C2H4O ) 8C3H6OH , C13H27O ( C2H4O ) 9C3H6OH , C13H27O ( C2H4O ) 10 ( C3H6O ) 2H , and C16H27O ( C2H4O ) 12 ( C3H6O ) 2H can be used.
• the content of nonionic surfactant (2) is preferably 2 to 12 parts by mass, more preferably 4 to 12 parts by mass, per 100 parts by mass of fluororesin in the dispersion. If it is equal to or greater than the lower limit of the above range, good storage stability is likely to be obtained. A high content of nonionic surfactant (2) is suitable for applications requiring thick application, but no improvement in performance is observed even if the content exceeds the upper limit of the above range, and for economic reasons, it is preferable to keep it below the upper limit of the above range.
• the number of carbon atoms in the alkyl group represented by R2 is preferably in the range of 6 to 18, more preferably 8 to 16, and even more preferably 10 to 14.
• the number of carbon atoms in the alkyl group is equal to or greater than the lower limit of the range, the surface tension of the dispersion is likely to be low and the wettability is likely to be increased.
• the number of carbon atoms in the alkyl group is equal to or less than the upper limit of the range, the storage stability of the dispersion is excellent.
• the number of carbon atoms in the alkyl group is within the above range, the wettability and storage stability are good.
• the alkyl group represented by R2 has a branched structure, it is preferable since the wettability of the dispersion liquid can be more easily increased.
• the branched carbon atom may be a secondary carbon atom or a tertiary carbon atom, and a secondary carbon atom is preferable.
• Examples of the alkyl group having a branched structure include C10H21CH(CH3)CH2-, C9H19CH(C3H7)-, C6H13CH(C6H13 ) - , CH (CH3)2CH2CH ( CH3 ) 2CH2CH ( CH ( CH3 ) 2CH2- , and the like .
• the alkyl group represented by R2 may have up to 10% of the hydrogen atoms in the alkyl group substituted with a halogen element such as a fluorine atom, a chlorine atom, a bromine atom, etc.
• the alkyl group may also contain 1 to 2 unsaturated bonds.
• E in the general formula (3) is a polyoxyalkylene chain consisting of 1 to 3 oxybutylene groups and 5 to 20 oxyethylene groups.
• the number of oxybutylene groups is preferably 1 to 2.5, more preferably 1 to 2.
• the defoaming property, wettability and viscosity properties tend to be good.
• the viscosity increase of the dispersion is suppressed, and good stability is likely to be obtained.
• the properties such as viscosity, stability, defoaming property and wettability are good, which is preferable.
• the oxybutylene group may be branched or linear, with branched being preferred.
• Examples of oxybutylene groups include -CH2- CH( C2H5 )-O-, -CH ( C2H5 )CH2 - O-, -CH( CH3 )-CH ( CH3 )-O-, -CH2CH2 -CH( CH3 ) -O- , -CH2CH2CH2 - O- and the like . Of these, -CH2 - CH( C2H5 )-O-, -CH( C2H5 ) CH2 - O- and -CH2CH2 - CH ( CH3 )-O- are preferable.
• Examples of raw materials for the oxybutylene group include various butylene oxides, and specific examples include 1,2-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, and methyloxetane.
• the number of oxyethylene groups in the polyoxyalkylene chain is 5 to 20, preferably 6 to 15, and more preferably 7 to 13. If it is equal to or greater than the lower limit of the above range, the storage stability of the dispersion tends to be good. If it is equal to or less than the upper limit, the wettability tends to be good. If it is within the above range, the properties such as viscosity, stability, defoaming property, and wettability are good, which is preferable.
• the oxybutylene groups in the polyoxyalkylene chain may have a block structure or a random structure.
• the oxybutylene group may be present in any portion of the polyoxyalkylene chain, but is preferably present in the range from the R 2 -O- group side to up to 70% of the total length of the polyoxyalkylene chain, and more preferably present in the range from the R 2 -O- group side to up to 50% of the total length of the polyoxyalkylene chain.
• the portion of the polyoxyalkylene chain bonded to the R 2 -O- group is preferably an oxybutylene group, more preferably a polyoxybutylene chain consisting of 1 to 2 oxybutylene groups.
• the portion of the polyoxyalkylene chain bonded to the G group is preferably an oxyethylene group, more preferably a polyoxyethylene chain consisting of 5 to 20 oxyethylene groups.
• Polyoxyalkylene chains having these preferred structures are preferred because they have better properties such as viscosity, stability, antifoaming property, and wettability.
• G is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.
• the nonionic surfactant (3) can be obtained by addition reaction of butylene oxide and ethylene oxide with a higher alcohol by a known method. Butylene oxide and ethylene oxide may be mixed and reacted simultaneously, butylene oxide may be reacted first and then ethylene oxide, or ethylene oxide may be reacted first and then butylene oxide. The method of reacting butylene oxide first and then ethylene oxide is preferred.
• nonionic surfactant ( 3 ) examples include C13H27OCH2CH ( C2H5 )O (C2H4O ) 8H , C10H21CH ( CH3 ) CH2OCH2CH ( C2H5 ) O ( C2H4O ) 8 H , C10H21CH ( CH3 ) CH2OCH ( C2H5 ) CH2O ( C2H4O ) 8H , C12H25OCH2CH ( C2H5 )O( C2 H4O ) 8H , C8H17 OCH2CH ( C2H5 )O ( C2H4O ) 10 H , C12H25OCH2CH ( C2H5 ) O ( C2H4O ) 10H , C13H27OCH2CH ( C2H5 )O( C2H4O ) 11H , C13H27OCH2CH2 OCH2CH ( C2H5 )O( C2H4O ) 11
• the content of nonionic surfactant (3) is preferably 0.1 to 12 parts by mass, more preferably 0.5 to 11 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the fluororesin in the dispersion. If the content is equal to or greater than the lower limit of the above range, good storage stability is likely to be obtained. In addition, cracks are less likely to occur in the fluororesin coating film, and repellency is less likely to occur.
• a high content of nonionic surfactant (3) is suitable for applications where a thick coating is required, but no improvement in performance is observed even if the content exceeds the upper limit of the above range, and for economic reasons, it is preferable to be equal to or less than the upper limit of the above range.
• the number of oxybutylene groups per molecule of the nonionic surfactant is preferably 0.5 to 2, more preferably 0.7 to 1.7, and even more preferably 0.9 to 1.5.
• the nonionic surfactant (2) and the nonionic surfactant (3) may be added separately.
• a mixture containing the nonionic surfactant (3) and the nonionic surfactant (2) produced as a by-product during the preparation of the nonionic surfactant (3) may also be used.
• the dispersion contains water as a dispersion medium for the fluororesin particles.
• This water may be water contained in the aqueous emulsion obtained by emulsion polymerization, or may be water prepared separately from the water in the aqueous emulsion.
• the dispersion may contain, as necessary, one or more of a pH adjuster (e.g., ammonia, etc.), an anionic surfactant, a polyethylene oxide-based thickener, a polyurethane-based thickener, a thixotropic agent, a silicone-based wettability improver, a fluorine-based wettability improver, a preservative, etc.
• a pH adjuster e.g., ammonia, etc.
• an anionic surfactant e.g., a polyethylene oxide-based thickener, a polyurethane-based thickener, a thixotropic agent, a silicone-based wettability improver, a fluor
• a water-soluble organic solvent e.g., toluene, xylene, etc.
• a pigment e.g., titanium oxide, iron oxide, carbon black, cobalt blue, etc.
• a glass powder e.g., hollow glass beads, a colorant (e.g., graphite particles, silica particles, mica or titanium oxide-coated mica powder, etc.) may be blended.
• the mixing of fluororesin 1 and fluororesin 2 can be carried out by mixing the crushed material containing fluororesin 1 after the above-mentioned washing with fluororesin 2.
• the crushed material consists essentially of fluororesin 1.
• the crushed material is preferably in a powder form. That is, when the crushed material such as cuttings directly generated during the production of the secondary molded body is washed, it is preferable to crush and finely pulverize the washed cuttings with a crusher or the like to obtain a powder.
• embodiments (1) to (4) are exemplified, with embodiment (4) being preferred.
• Powdered fluororesin 1 (crushed material) is mixed in a dry state with powdered fluororesin 2.
• Powdered fluororesin 1 (crushed material) is mixed with a dispersion in which fluororesin 2 is dispersed.
• the dispersion liquid in which the fluororesin 1 (crushed material) is dispersed is mixed with powdered fluororesin 2.
• the dispersion in which the fluororesin 1 (crushed material) is dispersed and the dispersion in which the fluororesin 2 is dispersed are mixed.
• the dispersion in which the fluororesin 1 is dispersed is preferably a dispersion obtained by mixing the powdered fluororesin 1 produced by the above-mentioned production method with a water-soluble organic solvent.
• the water-soluble organic solvent is preferably one or more water-soluble organic solvents selected from the group consisting of aprotic water-soluble organic solvents and alcohols.
• the alcohols may have an amino group or an alkoxy group as a substituent.
• aprotic water-soluble organic solvent acetone, tetrahydrofuran, or acetonitrile is preferred.
• methanol, ethanol, propanol, isopropyl alcohol, or 1-methoxy-2-propanol is preferred.
• water-soluble organic solvent isopropyl alcohol is more preferred.
• water-soluble organic solvent one type may be used alone, or two or more types may be used in combination.
• the content of fluororesin 1 relative to the total mass of the dispersion in which fluororesin 1 is dispersed is preferably 3 to 70 mass%, more preferably 5 to 65 mass%, and even more preferably 10 to 60 mass%.
• a dispersion liquid in which fluororesin 2 is dispersed As the dispersion liquid in which fluororesin 2 is dispersed, a dispersion liquid in which fluororesin 2 is dispersed by the above-mentioned emulsion polymerization is preferable.
• a dispersion liquid in which a nonionic surfactant is added to the dispersion liquid to improve storage stability may be used.
• powdered fluororesin 2 the powdered fluororesin 2 obtained by separating the fluororesin 2 from the solvent by filtering, drying, or the like from the dispersion liquid in which fluororesin 2 is dispersed may be used.
• the content of fluororesin 2 relative to the total mass of the dispersion in which fluororesin 2 is dispersed is preferably 5 to 40 mass%, more preferably 7 to 35 mass%, and even more preferably 10 to 30 mass%.
• the combined content of fluororesin 1 and fluororesin 2 relative to the total mass of the mixture is preferably 10 to 50 mass%, more preferably 12 to 45 mass%, and even more preferably 15 to 35 mass%.
• the combined content of fluororesin 1 and fluororesin 2 is equal to or greater than the lower limit of the above range, fluororesin 1 and fluororesin 2 tend to aggregate and are more likely to undergo solid-liquid separation.
• the combined content of fluororesin 1 and fluororesin 2 is equal to or less than the upper limit of the above range, mixing of fluororesin 1 and fluororesin 2 is more likely to be promoted.
• the content of the water-soluble organic solvent relative to 100 parts by mass of water in the mixture is preferably 1 to 150 parts by mass, more preferably 3 to 140 parts by mass, and even more preferably 5 to 130 parts by mass.
• the mixture may be washed.
• the mixture may be washed by adding a washing liquid to the mixture containing the powdered fluororesin 1 and fluororesin 2.
• the mixture is stirred and agglomerated to obtain an agglomerate.
• the agglomerate is filtered to separate the agglomerate and the solvent, and the agglomerate is washed with a large amount of water. Thereafter, the mixture is dried to obtain a mixture containing the powdered fluororesin 1 and fluororesin 2.
• the cleaning liquid for washing the mixture examples include water and organic solvents. Also, a cleaning liquid such as an aqueous solution containing two or more of these may be used. The amount of cleaning liquid used is preferably 10 to 5,000 parts by mass, more preferably 50 to 4,000 parts by mass, and even more preferably 100 to 3,000 parts by mass, relative to 100 parts by mass of the solid content of the mixture. Washing may be performed by method 1, in which the mixture is immersed in the cleaning liquid and left to stand, method 2, in which the mixture is stirred, or method 3, in which the cleaning liquid is poured over.
• the immersion time is preferably more than 0 hours and not more than 100 hours, more preferably more than 0 hours and not more than 80 hours, and even more preferably more than 0 hours and not more than 60 hours.
• the temperature of the cleaning liquid is preferably 0 to 200°C, and more preferably 10 to 150°C.
• washing is preferably performed 1 to 30 times, more preferably 1 to 25 times, and even more preferably 2 to 20 times.
• washing in method 3 is preferably performed multiple times.
• the fluororesin composition produced by the production method of this embodiment contains fluororesin 1 and fluororesin 2.
• the fluororesin composition may contain one or more solid components other than the fluororesin 1 and fluororesin 2.
• other solid components include solid components used in the production process of fluororesin 1, solid components used in the production process of fluororesin 2, and solid components added after the production of fluororesin 1 and fluororesin 2.
• Specific examples include inorganic fillers, pigments (for example, titanium oxide, iron oxide, carbon black, cobalt blue, etc.), colorants (for example, graphite particles, silica particles, mica or titanium oxide-coated mica powder, etc.), and the above-mentioned additives.
• inorganic fillers include reinforcing fibers (glass fibers, carbon fibers, etc.), glass powder, bronze powder, graphite powder, hollow glass beads, and the like.
• the content of other solid components is preferably 70 mass % or less, more preferably 60 mass % or less, and even more preferably 50 mass % or less, based on the total mass of the solid contents of the fluororesin composition. It may be zero.
• the total content of fluororesin 1 and fluororesin 2 relative to the total mass of the solid content of the fluororesin composition is preferably 30 to 100 mass%, more preferably 40 to 100 mass%, and even more preferably 50 to 100 mass%.
• the fluororesin composition is preferably in a solid form, and more preferably in a powder form.
• the content of fluororesin 1 relative to the total mass of fluororesin 1 and fluororesin 2 is preferably 10 mass% or more, more preferably 10 to 90 mass%, even more preferably 15 to 85 mass%, and particularly preferably 20 to 80 mass%.
• the molded body of the present embodiment can be obtained by compression molding the powdered fluororesin composition described above, followed by sintering. Specifically, a powdered fluororesin composition is placed in a mold, compressed and molded under pressure to obtain a preform, and the preform is fired to obtain a primary molded body.
• the shape of the primary molded body is not particularly limited. For example, it may be a block shape such as a cylindrical or polygonal column shape.
• the fluororesin composition When the fluororesin composition is compression molded, it is preferable to apply a pressure of 100 to 350 kg/cm 2 .
• the firing temperature after the preforming is preferably 360 to 380°C.
• the obtained molded body may be processed by cutting or other processes to produce a molded body (secondary molded body) of a desired shape.
• secondary molded bodies include seals, packing, rollers, sockets, and joints.
• the molded body of this embodiment may be the primary molded body or the secondary molded body.
• the chemical resistance of the molded article can be evaluated by immersion tests 1 to 3 in the examples described later.
• the mass change rate 1 in the immersion test 1 is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less.
• the mass change rate 2 in the immersion test 2 is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less.
• the mass change rate 3 in the immersion test 3 is preferably 8% or less, more preferably 5% or less, and even more preferably 1% or less.
• the fluororesin composition of the present invention contains a fluororesin 1 having a thermal history of being heated to a melting point or higher.
• the fluororesin 1 originates from cuttings or the like during the production of the above-mentioned secondary molded body, it may be contaminated with trace amounts of impurities such as oil stains and dust from the cutting process or the like.
• the inventors of the present application have found for the first time that the inclusion of such impurities impairs the chemical resistance of the molded body obtained from the fluororesin composition. It has also been found that the deterioration of chemical resistance can be suppressed and the recycling efficiency of the fluororesin can be increased by washing the crushed material such as the cuttings.
• Example 1 is an embodiment and Example 2 is a reference example.
• a laser diffraction/scattering type particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.) was used to disperse the powdered fluororesin in water, and the particle size distribution was measured and calculated on a number basis.
• the crushed material before and after washing which will be described later, was heated from 30 to 280° C. at a rate of 10° C./min using a NEXTA STA200 manufactured by Hitachi High-Tech Science Corporation, and the rate of thermal weight loss was measured according to the above formula I.
• Example 1 (Immersion test 1) 0.5 g of the molded article obtained in Example 1 or Example 2 was placed in a container, 35 mL of hydrofluoric acid with a concentration of 46.0 to 48.0 mass % was added, the container was sealed, and the container was left to stand at 85°C for 7 days while changing the liquid every day, after which the molded article was washed with water and dried, and the mass of the molded article after the immersion test was measured.
• Example 2 (Immersion test 2) 0.5 g of the molded article obtained in Example 1 or Example 2 was placed in a container, and a mixed solution of sulfuric acid and hydrogen peroxide (volume ratio of 98% sulfuric acid:30% hydrogen peroxide solution 2:1) was added until the molded article was completely immersed, and the container was sealed and left to stand at 80°C for 7 days while changing the solution every day, after which the molded article was washed with water and dried, and the mass of the molded article after the immersion test was measured.
• the mass change rate 2 was calculated by the following formula III.
• Mass change rate 2 (W B3 ⁇ W A3 )/W B3 ⁇ 100 Formula III
• W B3 is the mass of the molded body before the immersion test
• W A3 is the mass of the molded body after the immersion test.
• Mass change rate 3 (W B4 - W A4 )/W B4 ⁇ 100 Formula IV
• W B4 is the mass of the molded article before the immersion test
• W A4 is the mass of the molded article after the immersion test.
• Fluororesin B is a fluororesin having a thermal history of being heated to a melting point or higher.
• the melting point of the obtained fluororesin B was 329°C.
• the obtained fluororesin B was non-melt moldable because there was no temperature at which the melt flow rate was 0.1 to 1000 g/10 min at a temperature 20°C or higher than the melting point of the resin under a load of 49 N.
• 200 g of fluororesin B and 200 g of isopropanol were mixed to obtain dispersion B.
• the content of fluororesin B relative to the total mass of dispersion B was 50 mass%.
• the crushed material before washing had a thermal weight loss rate calculated from the above formula I of 4.4%, and the melting point was 326° C.
• the crushed material after washing had a thermal weight loss rate calculated from the above formula I of 0%.
• the content of the fluororesin C in the dispersion C relative to the total mass of the dispersion C was about 25.0 mass%, and the EEA concentration was 0.40 mass parts relative to 100 mass parts of the fluororesin C.
• the average particle size of the fluororesin C in the dispersion C was 0.26 ⁇ m.
• the standard specific gravity (SSG) of fluororesin C was 2.21.
• the melting point of fluororesin C was 337° C.
• the obtained fluororesin C did not have a temperature at which the melt flow rate was 0.1 to 1000 g/10 min at a temperature 20° C. or more higher than the melting point of the resin under a load of 49 N, and was therefore non-melt moldable.
• Example 1 798 g of dispersion C and 802 g of water were placed in an 8 L stainless steel tank equipped with a baffle and a stirrer and stirred. 400 g of dispersion B was added to the stirred dispersion C to obtain dispersion D containing a mixture of fluororesin B and fluororesin C. The mass ratio of fluororesin B to fluororesin C in dispersion D (fluororesin B:fluororesin C) was 1:1. The mass ratio of IPA to water in dispersion D (IPA:water) was 12:88. The total content of fluororesin B and fluororesin C relative to the total mass of dispersion D was 20.0 mass%.
• the mixture was stirred at 680 rpm for 10 minutes using a stirrer to aggregate the solids in the dispersion D, and the aggregates and the solvent were separated by filtration.
• the filtered aggregates were washed with a large amount of water, and then the aggregates were placed in a tray and vacuum dried at 25 ° C. for 2 hours or more, and then dried at 200 ° C. for 10 hours or more to obtain a fluororesin composition 1, which is a mixture of powdered fluororesin B and powdered fluororesin C. 345 g of the obtained fluororesin composition 1 was placed in a mold with a diameter of 7.3 mm and pressed at 320 kg / cm 2 to obtain a preform.
• This preform was baked at 380 ° C. for 2 hours to obtain a molded body.
• the obtained molded body was skived to prepare a sheet with a thickness of 0.5 mm, and a test piece was punched into a microdumbbell shape of 16 mm ⁇ 45 mm to obtain a molded body 1.
• Immersion tests 1 to 3 were performed using the molded body 1. The results are shown in Table 1.
• Example 2 A molded body was prepared in the same manner as in Example 1, except that fluororesin A was used instead of fluororesin composition 1, to obtain molded body 2, which is a microdumbbell-shaped test piece. Immersion tests 1 to 3 were carried out using molded body 2. The results are shown in Table 1.
• the molded body 1 of Example 1 showed a small mass change rate in immersion tests 1 to 3, and was found to have excellent chemical resistance.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=93657610

Family Applications (1)

Country Status (4)

Citations (9)

• 2024
  • 2024-05-30 JP JP2025524888A patent/JPWO2024248107A1/ja active Pending
  • 2024-05-30 EP EP24815587.1A patent/EP4722275A1/en active Pending
  • 2024-05-30 WO PCT/JP2024/019936 patent/WO2024248107A1/ja not_active Ceased
• 2025
  • 2025-12-01 US US19/404,187 patent/US20260085182A1/en active Pending

Patent Citations (9)

Also Published As

Similar Documents

Legal Events