Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F6/00—Post-polymerisation treatments
  • C08F6/14—Treatment of polymer emulsions
  • C08F6/16—Purification
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F14/00—Homopolymers and 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
  • C08F14/18—Monomers containing fluorine
  • C08F14/26—Tetrafluoroethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F114/00—Homopolymers 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
  • C08F114/18—Monomers containing fluorine
  • C08F114/26—Tetrafluoroethene

Definitions

• the present disclosure relates to a method for producing purified polytetrafluoroethylene powder and a low molecular weight polytetrafluoroethylene powder.
• Low molecular weight polytetrafluoroethylene also called “polytetrafluoroethylene wax” or “polytetrafluoroethylene micropowder”
• polytetrafluoroethylene wax also called “polytetrafluoroethylene wax” or “polytetrafluoroethylene micropowder”
• fibrillation since fibrillation does not easily occur, it is used as an additive to improve the slipperiness and texture of the coating surface in the production of plastics, inks, cosmetics, paints, greases, etc. (see, for example, Patent Document 1) .
• Polymerization methods radiation decomposition methods, thermal decomposition methods, and the like are known as methods for producing low molecular weight polytetrafluoroethylene.
• the present disclosure aims to provide a method for producing purified polytetrafluoroethylene powder that reduces short chain fluorine compounds from low molecular weight polytetrafluoroethylene.
• the present disclosure also aims to provide a low molecular weight polytetrafluoroethylene powder with a low content of specific fluorine compounds.
• Present disclosure (1) Including the process of reducing short chain fluorine compounds from low molecular weight polytetrafluoroethylene powder obtained by radical polymerization,
• this method reduces at least the compound represented by the following general formula (1) to 179 ppb or less and the compound represented by the following general formula (2) to 6900 ppb or less.
• this method reduces at least the compound represented by the following general formula (1) to 179 ppb or less and the compound represented by the following general formula (2) to 6900 ppb or less.
• M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), imidazolium which may have a substituent, pyridinium, which may have a substituent, or phosphonium, which may have a substituent.q is 1 or 2.
• Present disclosure (2) The method for producing purified polytetrafluoroethylene powder according to (1) of the present disclosure, wherein a fluorine-based surfactant other than perfluorooctanoic acid and its salt is used in the radical polymerization.
• Present disclosure (3) The method for producing purified polytetrafluoroethylene powder according to (1) or (2) of the present disclosure, wherein a hydrocarbon chain transfer agent is used in the radical polymerization.
• Present disclosure (4) The method for producing purified polytetrafluoroethylene powder according to any one of the present disclosure (1) to (3), wherein the radical polymerization is emulsion polymerization.
• Present disclosure (5) The method for producing purified polytetrafluoroethylene powder according to any one of (1) to (4) of the present disclosure, wherein the short-chain fluorine compound is reduced by heat treatment at 170° C. or higher.
• Present disclosure (6) The purified polytetrafluoroethylene powder according to any one of the present disclosure (1) to (5), wherein the low molecular weight polytetrafluoroethylene powder has a melt viscosity of 1 ⁇ 10 2 to 7 ⁇ 10 5 Pa ⁇ s at 380°C. manufacturing method.
• This disclosure (7) The method for producing purified polytetrafluoroethylene powder according to any one of (1) to (6) of the present disclosure, wherein in the step, perfluorocarboxylic acid and its salt are further reduced to below the limit of quantification.
• Present disclosure (8) The method for producing purified polytetrafluoroethylene powder according to the present disclosure (7), wherein the perfluorocarboxylic acid is a perfluorocarboxylic acid other than perfluorooctanoic acid.
• the content of perfluorocarboxylic acid and its salt is below the quantification limit, the content of the compound represented by the following general formula (1) is 179 ppb or less, and the content of the compound represented by the following general formula (2) is 6900 ppb or less.
• M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), imidazolium which may have a substituent, pyridinium, which may have a substituent, or phosphonium, which may have a substituent.q is 1 or 2.
• the low molecular weight polytetrafluoroethylene powder according to (9) of the present disclosure which has an average particle diameter of 20 ⁇ m or less and an apparent density of 0.6 g/ml or less.
• purified polytetrafluoroethylene powder with reduced short-chain fluorine compounds can be obtained.
• the low molecular weight polytetrafluoroethylene powder of the present disclosure has a low content of a specific fluorine compound.
• the manufacturing method of the present disclosure includes a step of reducing short-chain fluorine compounds from low molecular weight polytetrafluoroethylene (low molecular weight PTFE) powder obtained by radical polymerization.
• low molecular weight PTFE low molecular weight polytetrafluoroethylene
• a low molecular weight PTFE powder is obtained by radical polymerization.
• the polymerization of low molecular weight PTFE may be carried out by combining radical polymerization and other polymerizations, but it is preferable to carry out only radical polymerization. Thereby, the manufacturing procedure can be simplified.
• radical polymerization examples include emulsion polymerization, suspension polymerization, bulk polymerization, etc., but emulsion polymerization is preferred.
• the emulsion polymerization is usually carried out by carrying out a polymerization reaction of tetrafluoroethylene in an aqueous medium in the presence of a fluorosurfactant and a chain transfer agent.
• the method and conditions for the polymerization reaction are not particularly limited, and can be carried out by conventionally known methods.
• the above-mentioned fluorine-based surfactant is a compound that contains at least one fluorine atom in its molecular structure and exhibits surface activity.
• the above-mentioned fluorine-based surfactants include hydrocarbons having 2 to 7 carbon atoms in which at least one hydrogen atom has been replaced with a fluorine atom, carboxylic acids, carboxylic acid salts, sulfonic acids, and sulfonic acid groups. Examples include those consisting of hydrophilic groups such as.
• the above-mentioned fluorine-based surfactant is preferably one other than perfluorooctanoic acid and its salt.
• the aqueous medium is preferably deionized, highly purified water. Further, the aqueous medium may contain an organic solvent such as alcohol, ether, ketone, paraffin wax, or the like.
• Examples of the chain transfer agent include hydrogen, hydrocarbons, halogenated hydrocarbons, and the like.
• a hydrocarbon chain transfer agent such as a hydrocarbon or a halogenated hydrocarbon
• a short chain fluorine compound is produced as described above. Since the manufacturing method of the present disclosure includes a step of reducing short-chain fluorine compounds, the amount of short-chain fluorine compounds in low molecular weight PTFE can be reduced even if a hydrocarbon chain transfer agent is used.
• hydrocarbon chain transfer agent examples include hydrocarbons having 1 to 3 carbon atoms, halogenated hydrocarbons having 1 to 3 carbon atoms, and the like.
• hydrocarbons having 1 to 3 carbon atoms include methane, ethane, propane, etc.
• halogenated hydrocarbons having 1 to 3 carbon atoms include chloromethane, chloroethane, etc. Among these, ethane and propane are preferred.
• the appropriate amount of the chain transfer agent to be added cannot be unconditionally specified, since the appropriate range varies depending on the polymerization conditions such as its chain transfer ability, reaction temperature, polymerization pressure, or amount of polymerization initiator added.
• the amount is preferably 0.2 to 20 mol%, more preferably 1.0 to 10 mol%, based on the TFE present in the system.
• the low molecular weight PTFE powder is generally a TFE polymer having a number average molecular weight of 600,000 or less.
• High molecular weight PTFE powder with a number average molecular weight exceeding 600,000 exhibits fibrillation characteristics unique to PTFE (see Patent Document 1), so when used as an additive, the PTFE particles tend to aggregate with each other, causing damage to the matrix material. Dispersibility tends to be poor.
• the low molecular weight PTFE powder is preferably a TFE polymer having a melt viscosity of 1 ⁇ 10 2 to 7 ⁇ 10 5 (Pa ⁇ s) at 380°C.
• the number average molecular weight is usually 600,000 or less (see Patent Document 1).
• the high molecular weight PTFE powder is generally non-melt processable and differs from the low molecular weight PTFE powder in that its melt viscosity cannot be measured.
• the above melt viscosity was measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2 ⁇ -8L die, using a 2g sample preheated at 380°C for 5 minutes under a load of 0.7MPa. This is a value measured while maintaining the above temperature.
• the above number average molecular weights are values calculated from the melt viscosity measured by the above measuring method.
• the PTFE constituting the low molecular weight PTFE powder may be a tetrafluoroethylene homopolymer [TFE homopolymer] or a modified polytetrafluoroethylene [modified PTFE].
• the above TFE homopolymer is obtained by polymerizing only tetrafluoroethylene [TFE] as a monomer.
• the above-mentioned modified PTFE means a polymer obtained by copolymerizing TFE with a modifying monomer that can be copolymerized with TFE.
• the modified monomer in the modified PTFE is not particularly limited as long as it can be copolymerized with TFE; for example, perfluoroolefins such as hexafluoropropylene [HFP]; chlorotrifluoroethylene [CTFE] and other Examples include fluoroolefins; hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride [VDF]; perfluorovinyl ether; perfluorobutyl ethylene; and ethylene.
• the number of modified monomers used may be one or more than one.
• Rf represents a perfluoro organic group.
• Examples include perfluoro unsaturated compounds represented by the following formula.
• perfluoro organic group means an organic group in which all hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms.
• the perfluoro organic group may have an ether oxygen.
• perfluorovinyl ether examples include perfluoro(alkyl vinyl ether) [PAVE] in which Rf in the general formula (X) represents a perfluoroalkyl group having 1 to 10 carbon atoms.
• the perfluoroalkyl group preferably has 1 to 5 carbon atoms.
• perfluoroalkyl group in PAVE examples include perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, etc.
• Purple oro(propyl vinyl ether) [PPVE] in which the group is a perfluoropropyl group is preferred.
• the above-mentioned perfluorovinyl ether further includes those in the above general formula (X) in which Rf is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and Rf is the following formula: (wherein a represents 0 or an integer from 1 to 4), Rf is a group represented by the following formula: (In the formula, b represents an integer of 1 to 4).
• Perfluoroalkylethylene is not particularly limited, and examples thereof include perfluorobutylethylene (PFBE), perfluorohexylethylene (PFHE), perfluorooctylethylene (PFOE), and the like.
• the modified monomer in the modified PTFE is preferably at least one selected from the group consisting of HFP, CTFE, VDF, PMVE, PPVE, PFBE, PFHE, CNVE, and ethylene.
• the modified PTFE preferably has modified monomer units in the range of 0.0001 to 2 mol%, more preferably in the range of 0.0001 to less than 1 mol%, and more preferably in the range of 0.0001 to 0.5 mol%. It is more preferably within the range of 0.001 to 0.2 mol %, and particularly preferably within the range of 0.001 to 0.2 mol %.
• At least the compound represented by the following general formula (1) is contained at 179 ppb or less (preferably 120 ppb or less, more preferably 70 ppb or less, still more preferably 40 ppb or less, particularly preferably below the limit of quantification)
• the compound represented by the following general formula (2) is reduced to 6900 ppb or less (preferably 2500 ppb or less, more preferably 2000 ppb or less, still more preferably below the limit of quantification). Note that all of these amounts are based on mass.
• M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), imidazolium which may have a substituent, pyridinium, which may have a substituent, or phosphonium, which may have a substituent.q is 1 or 2.
• methods for reducing short-chain fluorine compounds such as the compound represented by general formula (1) and the compound represented by general formula (2) include a method of heat-treating the low molecular weight PTFE powder.
• the above heat treatment method is not particularly limited, and may include a box dryer, band dryer, tunnel dryer, jet dryer, moving bed dryer, rotary dryer, fluidized bed dryer, flash dryer, box dryer, etc. dryer, disk dryer, cylindrical stirring dryer, inverted conical stirring dryer, microwave equipment, vacuum heat treatment equipment, box-shaped electric furnace, hot air circulation equipment, flash dryer, vibration dryer, belt dryer, extrusion dryer It can be carried out using a machine, spray dryer, etc.
• the above heat treatment may be performed on a wet PTFE powder containing water obtained from a PTFE dispersion after polymerization, or may be performed on a dried PTFE powder.
• the heating temperature is preferably 170° C. or higher from the viewpoint of efficiency in reducing short-chain fluorine compounds.
• a more preferable lower limit is 175°C, and an even more preferable lower limit is 180°C.
• the upper limit is preferably lower than the melting point of the low molecular weight PTFE powder.
• the melting point of low molecular weight PTFE powder is typically 327°C.
• a more preferable upper limit is 300°C, and an even more preferable upper limit is 240°C.
• the heating time is preferably 5 to 30 hours from the viewpoint of efficiency in reducing short-chain fluorine compounds.
• a more preferable lower limit is 7 hours, and an even more preferable lower limit is 10 hours.
• a more preferable upper limit is 25 hours, and an even more preferable upper limit is 22 hours.
• the above-mentioned heating time is the total time of these.
• the compound represented by the general formula (1) and the compound represented by the general formula (2) which are short chain fluorine compounds, are reduced from the low molecular weight PTFE powder.
• the above-mentioned short-chain fluorine compounds include perfluorocarboxylic acids and salts thereof, in addition to the compounds represented by the general formula (1) and the compounds represented by the general formula (2). That is, in the manufacturing method of the present disclosure, it is preferable that the perfluorocarboxylic acid and its salt be further reduced to below the quantification limit in the above steps.
• the perfluorocarboxylic acid preferably has 4 to 14 carbon atoms. Further, the perfluorocarboxylic acid may be perfluorooctanoic acid or a perfluorocarboxylic acid other than perfluorooctanoic acid, but perfluorooctanoic acid is preferable.
• the metal atoms include monovalent or divalent metal atoms, more specifically, alkali metals (group 1) or alkaline earth metals (group 2). Can be mentioned. Specifically, Na, K, Li, etc. are exemplified.
• the four R 5 's may be the same or different.
• the above R 5 is preferably H or an organic group having 1 to 10 carbon atoms, and more preferably H or an organic group having 1 to 4 carbon atoms. Further, preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms.
• the above provisions are applicable to all R5s described below.
• m may be 5 to 11.
• n may be 6 to 12.
• organic group means a group containing one or more carbon atoms, or a group formed by removing one hydrogen atom from an organic compound.
• organic group examples include: an alkyl group that may have one or more substituents, Alkenyl group optionally having one or more substituents, an alkynyl group which may have one or more substituents, cycloalkyl group optionally having one or more substituents, Cycloalkenyl group optionally having one or more substituents, Cycloalkadienyl group optionally having one or more substituents, an aryl group which may have one or more substituents, an aralkyl group which may have one or more substituents, a non-aromatic heterocyclic group which may have one or more substituents, a heteroaryl group optionally having one or more substituents, cyano group, formyl group, RaO-, RaCO-, RaSO 2 ⁇ , RaCOO-,
• the organic group is preferably an alkyl group which may have one or more substituents. Further, the above-mentioned organic groups include those listed as examples of the substituents below.
• substituteduent means a substitutable group.
• the “substituents” include aliphatic groups, aromatic groups, heterocyclic groups, acyl groups, acyloxy groups, acylamino groups, aliphatic oxy groups, aromatic oxy groups, heterocyclic oxy groups, aliphatic oxycarbonyl groups, Aromatic oxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, aliphatic sulfonyl group, aromatic sulfonyl group, heterocyclic sulfonyl group, aliphatic sulfonyloxy group, aromatic sulfonyloxy group, heterocyclic sulfonyloxy group, sulfamoyl group , aliphatic sulfonamide group, aromatic sulfonamide group, heterocyclic sulfonamide group, amino group, aliphatic amino group, aromatic amino group, heterocyclic sulfonamide group, amino
• the above aliphatic group may be saturated or unsaturated, and may also be a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, or an aliphatic amino group. , an acylamino group, a carbamoylamino group, etc.
• the aliphatic group include an alkyl group having a total of 1 to 8 carbon atoms (preferably 1 to 4 carbon atoms). Specific examples include a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, a carbamoylmethyl group, and the like.
• the above aromatic group includes, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. You may do so.
• the aromatic group include aryl groups having a total number of carbon atoms of 6 to 12 (preferably 6 to 10). Specific examples thereof include phenyl group, 4-nitrophenyl group, 4-acetylaminophenyl group, and 4-methanesulfonylphenyl group.
• the above heterocyclic group has a halogen atom, hydroxy group, aliphatic oxy group, carbamoyl group, aliphatic oxycarbonyl group, aliphatic thio group, amino group, aliphatic amino group, acylamino group, carbamoylamino group, etc. You can.
• Examples of the above-mentioned heterocyclic group include a 5- to 6-membered heterocyclic ring having a total number of carbon atoms of 2 to 12 (preferably 2 to 10). Specific examples thereof include 2-tetrahydrofuryl group and 2-pyrimidyl group.
• the above acyl group includes an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, and an amino group. , an aliphatic amino group, an acylamino group, a carbamoylamino group, etc.
• the acyl group include acyl groups having a total number of carbon atoms of 2 to 8 (preferably 2 to 4). Specific examples include an acetyl group, a propanoyl group, a benzoyl group, a 3-pyridinecarbonyl group, and the like.
• the above acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., and more specifically, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. It may have.
• Examples of the above-mentioned acylamino group include an acylamino group having a total number of carbon atoms of 2 to 12 (preferably 2 to 8), an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, and the like. Specific examples include an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, and the like.
• the aliphatic oxycarbonyl group may be saturated or unsaturated, and may also be a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic oxycarbonyl group, or an aliphatic oxycarbonyl group. It may have an amino group, an acylamino group, a carbamoylamino group, etc.
• the aliphatic oxycarbonyl group include alkoxycarbonyl groups having a total number of carbon atoms of 2 to 8 (preferably 2 to 4). Specific examples thereof include methoxycarbonyl, ethoxycarbonyl, and (t)-butoxycarbonyl groups.
• the carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.
• Examples of the carbamoyl group include an unsubstituted carbamoyl group, an alkylcarbamoyl group having 2 to 9 carbon atoms in total, and preferably an unsubstituted carbamoyl group and an alkylcarbamoyl group having 2 to 5 carbon atoms in total.
• Specific examples of the alkylcarbamoyl group include N-methylcarbamoyl group, N,N-dimethylcarbamoyl group, N-phenylcarbamoyl group, and the like.
• the aliphatic sulfonyl group may be saturated or unsaturated, and may also be a hydroxy group, aromatic group, aliphatic oxy group, carbamoyl group, aliphatic oxycarbonyl group, aliphatic thio group, or amino group. , an aliphatic amino group, an acylamino group, a carbamoylamino group, etc.
• Examples of the aliphatic sulfonyl group include alkylsulfonyl groups having a total number of carbon atoms of 1 to 6 (preferably 1 to 4). Specific examples thereof include methanesulfonyl and the like.
• the above aromatic sulfonyl group includes a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. You may do so.
• the aromatic sulfonyl group include arylsulfonyl groups having a total of 6 to 10 carbon atoms. Specific examples include benzenesulfonyl and the like.
• the above amino group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.
• the above acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, or the like.
• examples of the above-mentioned acylamino group include acylamino groups having a total number of carbon atoms of 2 to 12 (preferably 2 to 8).
• the acylamino group is preferably an alkylcarbonylamino group having 2 to 8 carbon atoms in total. Specific examples include an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, and the like.
• the aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, a 2-pyridine sulfonamide group, or the like.
• the sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.
• the above-mentioned sulfamoyl group includes a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 9 carbon atoms, a dialkylsulfamoyl group having a total of 2 to 10 carbon atoms, and an arylsulfamoyl group having a total of 7 to 13 carbon atoms.
• a heterocyclic sulfamoyl group having a total of 2 to 12 carbon atoms etc., such as a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 7 carbon atoms, a dialkylsulfamoyl group having a total of 3 to 6 carbon atoms, a total Arylsulfamoyl groups having 6 to 11 carbon atoms and heterocyclic sulfamoyl groups having 2 to 10 total carbon atoms are preferred.
• sulfamoyl group examples include sulfamoyl group, methylsulfamoyl group, N,N-dimethylsulfamoyl group, phenylsulfamoyl group, and 4-pyridinesulfamoyl group.
• the aliphatic oxy group may be saturated or unsaturated, and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, or the like.
• Examples of the aliphatic oxy group include alkoxy groups having a total number of carbon atoms of 1 to 8 (preferably 1 to 6). Specific examples thereof include methoxy group, ethoxy group, i-propyloxy group, cyclohexyloxy group, and methoxyethoxy group.
• the above aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group condensed with an aryl group, an aliphatic oxycarbonyl group, etc.
• Commonly used are aliphatic groups having 1 to 4 carbon atoms in total, aliphatic oxy groups having 1 to 4 total carbon atoms, halogen atoms, carbamoyl groups having 1 to 4 total carbon atoms, nitro groups, and 2 to 4 carbon atoms in total. It is preferable to have 4 aliphatic oxycarbonyl groups.
• the aliphatic thio group may be saturated or unsaturated, and may be an alkylthio group having a total of 1 to 8 carbon atoms (preferably 1 to 6). Specific examples thereof include methylthio group, ethylthio group, carbamoylmethylthio group, and t-butylthio group.
• the carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, or the like.
• the above carbamoylamino group includes a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 9 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 10 carbon atoms, an arylcarbamoylamino group having a total of 7 to 13 carbon atoms, Examples include a heterocyclic carbamoylamino group having a total of 3 to 12 carbon atoms, preferably a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 7 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 6 carbon atoms, These are an arylcarbamoylamino group having a total of 7 to
• carbamoylamino group examples include carbamoylamino group, methylcarbamoylamino group, N,N-dimethylcarbamoylamino group, phenylcarbamoylamino group, and 4-pyridinecarbamoylamino group.
• One form of purified PTFE powder obtained by the production method of the present disclosure includes the low molecular weight PTFE powder of the present disclosure.
• the low molecular weight PTFE powder of the present disclosure has a content of perfluorocarboxylic acid and its salt below the quantification limit, a content of the compound represented by the above general formula (1) below 179 ppb, and a content shown by the above general formula (2).
• the content of perfluorocarboxylic acid and its salt is below the quantification limit on a mass basis.
• the low molecular weight PTFE powder of the present disclosure is substantially free of perfluorocarboxylic acids and salts thereof.
• the limit of quantification of perfluorocarboxylic acid and its salt is 1 ng/mL when measured by the method described in Examples below.
• the content of the compound represented by the above general formula (1) is 179 ppb or less on a mass basis.
• the lower limit is not particularly limited, but is preferably 120 ppb or less, more preferably 70 ppb or less, even more preferably 40 ppb or less, and may be an amount below the limit of quantification.
• the low molecular weight PTFE powder of the present disclosure may not substantially contain the compound represented by the above general formula (1).
• the limit of quantification of the content of the compound represented by the above general formula (1) is 1 ng/mL when measured by the method described in Examples below.
• the content of the compound represented by the above general formula (2) is 6900 ppb or less on a mass basis.
• the lower limit is not particularly limited, but is preferably 2,500 ppb or less, more preferably 2,000 ppb or less, and may be an amount below the quantification limit.
• the low molecular weight PTFE powder of the present disclosure may not substantially contain the compound represented by the above general formula (2).
• the limit of quantification of the content of the compound represented by the above general formula (2) is 1 ng/mL when measured by the method described in Examples below.
• the perfluorocarboxylic acid may be perfluorooctanoic acid or a perfluorocarboxylic acid other than perfluorooctanoic acid, but perfluorooctanoic acid is preferable.
• the content of the perfluorocarboxylic acid and its salt, the compound represented by the general formula (1), and the compound represented by the general formula (2) can be measured by liquid chromatography.
• ESR spectrum first-order differential spectrum obtained by measurement by electron spin resonance (ESR) of 0 g -1 or more 7 g -1 or less.
• a positive signal means a signal that appears in the positive region of the spectrum (above the baseline)
• a negative signal means a signal that appears in the negative region of the spectrum (below the baseline). It means a signal that appears.
• the linear radical (radical 1) has the following formula: (The wavy line in the formula represents the polymer chain of PTFE. The same applies hereinafter), and the side chain type radical (radical 2) is represented by the following formula: It is indicated by.
• the low molecular weight PTFE powder of the present disclosure preferably has an average particle size of 20 ⁇ m or less.
• the lower limit of the average particle diameter is preferably 1 ⁇ m, more preferably 2 ⁇ m, and the upper limit is more preferably 11 ⁇ m, even more preferably 10 ⁇ m, and even more preferably 9 ⁇ m.
• the above average particle diameter was measured using a laser diffraction particle size distribution analyzer (HELOS&RODOS) manufactured by JEOL Ltd., without using a cascade, and at a dispersion pressure of 3.0 bar, and corresponds to 50% of the cumulative particle size distribution. Assume that it is equal to the particle size.
• HELOS&RODOS laser diffraction particle size distribution analyzer
• the low molecular weight PTFE powder of the present disclosure preferably has an apparent density of 0.6 g/ml or less.
• the lower limit of the apparent density is preferably 0.1 g/ml, more preferably 0.2 g/ml, and the upper limit is more preferably 0.5 g/ml.
• the above apparent density can be measured according to JIS K6891.
• the low molecular weight PTFE powder of the present disclosure can be manufactured, for example, by the manufacturing method of the present disclosure. Further, the low molecular weight PTFE powder of the present disclosure is preferably obtained by emulsion polymerization using a fluorine-based surfactant other than perfluorooctanoic acid and its salt.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure can be used in molding materials, inks, cosmetics, paints, greases, parts for office automation equipment, additives for modifying toner, and plating solutions. It can be suitably used as an additive to.
• the above additive is particularly suitable for use as a thickening agent for grease.
• molding material examples include engineering plastics such as polyoxybenzoyl polyester, polyimide, polyamide, polyamideimide, polyacetal, polycarbonate, and polyphenylene sulfide.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure are used as additives in the above-mentioned molding materials, they can be used for improving the non-stick properties and sliding properties of copy rolls, and for furniture.
• Applications for improving the texture of engineering plastic molded products such as surface sheets, automobile dashboards, and covers for home appliances; Mechanical friction in light load bearings, gears, cams, push-phone buttons, projectors, camera parts, sliding materials, etc. It can be used for purposes such as improving the slipperiness and wear resistance of mechanical parts that cause corrosion.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure can be used as an additive for paints for the purpose of improving the slipperiness of varnishes and paints.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure can be used as additives for cosmetics for purposes such as improving the slipperiness of cosmetics such as foundations.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure can be further used for improving the oil repellency or water repellency of wax etc., and for improving the slipperiness of grease and toner. is also suitable.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure can be used as an electrode binder for secondary batteries and fuel cells, a hardness modifier for electrode binders, a water repellent treatment agent for electrode surfaces, etc. Can be used.
• the purified PTFE powder obtained by the production method of the present disclosure and the low molecular weight PTFE powder of the present disclosure can also be mixed with lubricating oil to prepare grease.
• the above grease contains the purified PTFE powder or the low molecular weight PTFE powder and a lubricating oil, so that the purified PTFE powder or the low molecular weight PTFE powder is uniformly and stably dispersed in the lubricating oil, and it has a load capacity. It has excellent properties such as electrical insulation, low moisture absorption, etc.
• the lubricating oil (base oil) may be mineral oil or synthetic oil.
• Examples of the lubricating oil (base oil) include paraffinic and naphthenic mineral oils, synthetic hydrocarbon oils, ester oils, fluorine oils, and synthetic oils such as silicone oils. Fluorine oil is preferred from the viewpoint of heat resistance.
• Examples of the fluorine oil include perfluoropolyether oil, low polymers of trifluorochloroethylene, and the like.
• the low polymer of trifluorochloroethylene may have a weight average molecular weight of 500 to 1,200.
• the above grease may further contain a thickener.
• the thickener include metal soaps, composite metal soaps, bentonites, phthalocyanines, silica gels, urea compounds, urea-urethane compounds, urethane compounds, imide compounds, and the like.
• the metal soap include sodium soap, calcium soap, aluminum soap, lithium soap, and the like.
• the urea compound, urea urethane compound, and urethane compound include diurea compounds, triurea compounds, tetraurea compounds, other polyurea compounds, urea urethane compounds, diurethane compounds, and mixtures thereof.
• the total content of the purified PTFE powder and the low molecular weight PTFE powder is preferably 0.1 to 50% by mass.
• the lower limit is more preferably 0.5% by mass, and the upper limit is more preferably 30% by mass. If the amount of the purified PTFE powder and the low molecular weight PTFE powder is too large, the grease may become too hard and may not exhibit sufficient lubricity. If the amount of the purified PTFE powder and the low molecular weight PTFE powder is too small, the sealing property may not be able to perform effectively.
• the above grease may also contain a solid lubricant, an extreme pressure agent, an antioxidant, an oily agent, a rust inhibitor, a viscosity index improver, a detergent and dispersant, and the like.
• ⁇ Average particle diameter> Using a laser diffraction particle size distribution analyzer (HELOS&RODOS) manufactured by JEOL Ltd., measurements were performed at a dispersion pressure of 1.0 bar without using a cascade, and the particle size corresponding to 50% of the integrated particle size distribution was determined as the average particle size. And so.
• HELOS&RODOS laser diffraction particle size distribution analyzer
• the content of perfluorocarboxylic acid and its salt was measured using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC/TQD). The extracted liquid phase was measured using the MRM (Multiple Reaction Monitoring) method. The limit of quantification in this measurement is 1 ng/mL. In this example, the content of perfluorocarboxylic acids having 4 to 14 carbon atoms and their salts was calculated, and the total amount thereof was determined.
• the content of the compound represented by general formula (1) having carbon number (m+1) in the extract was calculated using the following formula.
• a and b were determined from the relational expression explained using the perfluorocarboxylic acid calibration curve.
• the content of compounds having 4 to 21 carbon atoms was calculated, and the total amount thereof was determined.
• XCm ((ACm-b)/a) ⁇ ((50 ⁇ m+45)/413)
• XCm Content (ng/mL) of a compound represented by general formula (1) with carbon number (m+1) in the extraction solution
• ACm Peak area of a compound represented by general formula (1) with carbon number (m+1) in the extraction solution. The limit of quantification in this measurement is 1 ng/mL.
• the content of the compound represented by the general formula (1) with carbon number (m+1) contained in the powder was determined by the following formula.
• YCm XCm ⁇ 12.6
• YCm Content of the compound represented by the general formula (1) with carbon number (m+1) contained in the powder (ppb vs. PTFE)
• Content of compound represented by general formula (2) The content of the compound represented by general formula (2) having n carbon atoms in the extract was calculated using the following formula. In the formula, a and b were determined from the relational expression explained using the perfluorooctanoic acid calibration curve. In this example, the content of compounds having 4 to 21 carbon atoms was calculated, and the total amount thereof was determined.
• XSn ((ASn-b)/a) ⁇ ((50 ⁇ n+81)/499)
• XSn content (ng/mL) of a compound represented by general formula (2) with n carbon atoms in the extraction solution
• ASn Peak area of a compound represented by general formula (2) with n carbon atoms in the extraction solution. The limit of quantification in this measurement is 1 ng/mL.
• the content of the compound represented by the general formula (2) having n carbon atoms contained in the powder was determined by the following formula.
• YSn XSn ⁇ 12.6
• ESR electron spin resonance
• Comparative example 1 14.7 g of nitric acid was added to 660 g of the above low molecular weight PTFE aqueous dispersion and coagulated by applying severe mechanical shearing force. Furthermore, the obtained wet powder was filtered and washed again with 750 g of pure water. After repeating this water washing operation five times, it was dried for 18 hours in a hot air circulation dryer at 150°C to obtain a powder of low molecular weight PTFE.
• Comparative example 2 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature (heating temperature) was 160°C.
• Example 1 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature was 170°C.
• Example 2 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature was 180°C.
• Example 3 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature was 200°C.
• Example 4 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature was 210°C.
• Example 5 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature was 230°C.
• Example 6 A low molecular weight PTFE powder was obtained in the same manner as in Comparative Example 1 except that the drying temperature was 240°C.
• the obtained low molecular weight PTFE powder was evaluated by the method described above. The results are shown in Table 9.

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• 2022
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