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Definitions

• the present disclosure relates to polymer blends, crosslinkable compositions and articles.
• a polymer blend containing a fluoroelastomer and a crystalline fluoropolymer which has a suitable hardness, has a small compression set at high temperatures, and is capable of producing an article that is unlikely to suffer from large compression set even after use under harsh conditions.
• a fluoroelastomer is an amorphous fluoropolymer.
• “Amorphous” refers to a fluoropolymer that has a melting peak ( ⁇ H) of 4.5 J/g or less in differential scanning calorimetry (DSC) (heating rate 10°C/min) or differential thermal analysis (DTA) (heating rate 10°C/min).
• DSC differential scanning calorimetry
• DTA differential thermal analysis
• Fluoroelastomers exhibit elastomeric properties by crosslinking. Elastomeric properties refer to the ability of a polymer to be stretched and to retain its original length when the force required to stretch the polymer is no longer applied.
• Mooney viscosity can be measured at 170°C using an ALPHA TECHNOLOGIES Mooney viscometer MV2000E in accordance with JIS K6300.
• the nitrogen-containing crosslinking moiety can be introduced into the fluoroelastomer, for example, by copolymerizing a monomer having a nitrogen-containing crosslinkable group when producing the fluoroelastomer.
• the nitrogen-containing crosslinking moiety can also be introduced into the fluoroelastomer, for example, by polymerizing a monomer in the presence of a nitrogen-containing chain transfer agent when producing the fluoroelastomer.
• Examples of the nitrogen-containing chain transfer agent include compounds represented by I(CF 2 ) n CN (n is an integer of 1 to 15).
• the fluoroelastomer (a) contains a monomer unit having a nitrogen-containing crosslinkable group.
• CF2 CFOCF( CF3 ) CF2O ( CF2 ) n -CN (In the formula, n is an integer of 1 or more).
• Formula: CF2 CFOCF2OCF2CF ( CF3 ) OCF2 -CN
• Formula: CF2 CFO( CF2 ) 3CN
• Formula: CF2 CFO( CF2 ) 5CN
• CF2 CF( OCF2CF ( CF3 )) mO ( CF2 ) n -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) is preferred, with CF 2 ⁇ CFOCF 2 CF(CF 3 )OCF 2 CF 2 CN being more preferred.
• the content of nitrogen-containing crosslinked sites can be measured by infrared spectroscopy (IR).
• the content of nitrogen-containing crosslinkable groups can be measured by infrared spectroscopy (IR).
• the cyano group content can be measured by infrared spectroscopy (IR).
• the melting point of the crystalline fluoropolymer (b) is 310 to 320°C.
• the melting point is preferably 311°C or higher, more preferably 312°C or higher, even more preferably 313°C or higher, and is preferably 319°C or lower, more preferably 318°C or lower.
• the melting point of the crystalline fluoropolymer (b) is too low, it may be difficult to obtain an article with small compression set at high temperatures. If the melting point of the crystalline fluoropolymer (b) is too high, it may be difficult to obtain an article that is unlikely to experience large compression set even after use under harsh conditions.
• the melting point of the crystalline fluoropolymer (b) can be adjusted to the above range, for example, by adjusting the composition of the monomers that make up the crystalline fluoropolymer (b). Increasing the content of tetrafluoroethylene units tends to increase the melting point of the crystalline fluoropolymer (b), and decreasing the content of tetrafluoroethylene units tends to decrease the melting point of the crystalline fluoropolymer (b).
• the melting point of the crystalline fluoropolymer (b) can be measured by weighing out approximately 10 mg of the crystalline fluoropolymer (b) that has not been heated to a temperature of 300°C or higher, placing it in a special aluminum pan, and using a TG/DTA (thermogravimetric/differential thermal analyzer).
• the aluminum pan is heated in an air atmosphere over a temperature range of 25°C to 600°C at a rate of 10°C/min to obtain a DTA curve, and the temperature corresponding to the peak in the obtained DTA curve is identified as the melting point of the polymer blend.
• a nitrogen-containing crosslinkable group is preferred.
• the nitrogen-containing crosslinkable group is not particularly limited as long as it contains at least one nitrogen atom and provides the fluoropolymer with a crosslinking site for forming a crosslink, but examples include a cyano group, an azide group, a sulfonyl azide group, a carbonyl azide group, and an amidine group.
• a cyano group is preferred, since it is possible to obtain an article with even smaller compression set at high temperatures and, further, to obtain an article in which the increase in compression set after use under harsh conditions is further suppressed.
• the nitrogen-containing crosslinking site can be introduced into the crystalline fluoropolymer, for example, by reacting a functional group (for example, -COF, -COOH, etc.) generated at the end of the crystalline fluoropolymer with ammonia after producing the crystalline fluoropolymer.
• a functional group for example, -COF, -COOH, etc.
• CF2 CFOCF( CF3 ) CF2O ( CF2 ) n -CN (wherein n is an integer of 1 or more)
• Formula: CF2 CFOCF2OCF2CF ( CF3 ) OCF2 -CN
• Formula: CF2 CFO( CF2 ) 3CN
• Formula: CF2 CFO( CF2 ) 5CN
• the content of nitrogen-containing crosslinking sites in the crystalline fluoropolymer (b) is preferably 0.5 to 3.0 mol%, more preferably 2.0 mol% or less, and even more preferably 1.5 mol% or less, when the total monomer units constituting the crystalline fluoropolymer (b) is taken as 100 mol%.
• the content of nitrogen-containing crosslinked sites can be measured by infrared spectroscopy (IR).
• Mooney viscosity can be measured at 170°C using an ALPHA TECHNOLOGIES Mooney viscometer MV2000E in accordance with JIS K6300.
• the glass transition temperature of the polymer blend is preferably -30°C or higher, more preferably -20°C or higher, even more preferably -10°C or higher, preferably 10°C or lower, more preferably 5°C or lower, and even more preferably 0°C or lower, because this can impart appropriate hardness to the article, can result in an article with even smaller compression set at high temperatures, and can result in an article with even more suppressed increase in compression set after use under harsh conditions.
• the glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter (Hitachi High-Tech Science Corporation, X-DSC7000) by heating 3 mg of sample at 20°C/min, and taking the temperature as the midpoint between the two intersection points of the extension of the baseline before and after the second-order transition of the DSC curve and the tangent to the inflection point of the DSC curve.
• a differential scanning calorimeter Haitachi High-Tech Science Corporation, X-DSC7000
• the polymer blend of the present disclosure contains a fluoroelastomer (a) and a crystalline fluoropolymer (b).
• the content of the crystalline fluoropolymer (b) in the polymer blend is 4.0 to 15.0 mass% based on the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).
• the content of crystalline fluoropolymer (b) in the polymer blend is preferably 4.2% by mass or more, more preferably 4.4% by mass or more, even more preferably 4.6% by mass or more, and preferably 14.0% by mass or less, more preferably 13.0% by mass or less, even more preferably 12.0% by mass or less.
• the polymer blend of the present disclosure contains a fluoroelastomer (a) and a crystalline fluoropolymer (b). Furthermore, the fluoroelastomer (a) contains tetrafluoroethylene units, fluoroalkyl vinyl ether units, and nitrogen-containing crosslinking sites, and the crystalline fluoropolymer (b) contains tetrafluoroethylene units and nitrogen-containing crosslinking sites.
• a fluoromonomer represented by general formula (11) is preferable, and at least one selected from the group consisting of CF 2 ⁇ CF-OCF 3 (perfluoro(methyl vinyl ether) (PMVE)), CF 2 ⁇ CF-OCF 2 CF 3 and CF 2 ⁇ CF-OCF 2 CF 2 CF 3 is more preferable, with CF 2 ⁇ CF-OCF 3 being even more preferable.
• the content ratio of tetrafluoroethylene units and fluoroalkyl vinyl ether units in the polymer blend is preferably 50/50 to 70/30, more preferably 51/49 or more, even more preferably 52/48 or more, still more preferably 53/47 or more, more preferably 69/31 or less, and even more preferably 68/32 or less, in terms of a molar ratio (tetrafluoroethylene units/fluoroalkyl vinyl ether units).
• the fluoroelastomer (a) and the crystalline fluoropolymer (b) contain nitrogen-containing crosslinking moieties.
• the nitrogen-containing crosslinking moieties are moieties that contain at least one nitrogen atom and are used to form crosslinks between the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the polymer blend.
• the nitrogen-containing crosslinking site can be introduced into the crystalline fluoropolymer, for example, by copolymerizing a monomer having a nitrogen-containing crosslinkable group when producing the fluoroelastomer and the crystalline fluoropolymer.
• the nitrogen-containing crosslinking site can also be introduced into the fluoroelastomer and the crystalline fluoropolymer, for example, by polymerizing a monomer in the presence of a nitrogen-containing chain transfer agent when producing the fluoroelastomer and the crystalline fluoropolymer.
• the nitrogen-containing chain transfer agent can be a compound represented by I(CF 2 ) n CN (n is an integer of 1 to 15).
• the nitrogen-containing crosslinking site can also be introduced into the fluoroelastomer and the crystalline fluoropolymer, for example, by reacting a functional group (for example, -COF, -COOH, etc.) generated at the end of the fluoroelastomer and the crystalline fluoropolymer with ammonia after producing the fluoroelastomer and the crystalline fluoropolymer.
• a functional group for example, -COF, -COOH, etc.
• Formula: CF2 CFOCF2 (CF( CF3 ) OCF2 ) nCF (-CN) CF3 (wherein n is an integer from 1 to 4).
• Formula: CF2 CFO( CF2 ) nOCF ( CF3 )-CN (wherein n is an integer from 2 to 5).
• Formula: CF2 CFO( CF2 ) n- ( C6H4 ) -CN (wherein n is an integer from 1 to 6)
• Formula: CF2 CF( OCF2CF ( CF3 )) nOCF2CF ( CF3 )-CN (wherein n is an integer of 1 to 2).
• Methods for preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) include a method of mixing an aqueous dispersion containing a fluoroelastomer (a) with an aqueous dispersion containing a crystalline fluoropolymer (b), a method of mixing a powder of a fluoroelastomer (a) with an aqueous dispersion containing a crystalline fluoropolymer (b), and a method of mixing an aqueous dispersion containing a fluoroelastomer (a) with a powder of a crystalline fluoropolymer (b).
• the method of mixing an aqueous dispersion containing a fluoroelastomer (a) with an aqueous dispersion containing a crystalline fluoropolymer (b) is preferred.
• the method for producing the fluoroelastomer (a) and the crystalline fluoropolymer (b) by two-stage polymerization includes the following: (2-1) In the presence of an aqueous medium, tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing a crystalline fluoropolymer (b), and then (2-2) preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of the crystalline fluoropolymer (b) and an aqueous medium; (2-3) A production method in which the fluoroelastomer (a) and the crystalline fluoropoly
• the polymerization in step (2-1) and the polymerization in step (2-2) can be carried out in the same reaction vessel or in different reaction vessels.
• the polymerization in step (2-2) can be started after terminating the polymerization in step (2-1), or the polymerization in step (2-2) can be started without terminating the polymerization in step (2-1).
• Polymerization initiators include oil-soluble radical polymerization initiators and water-soluble radical initiators.
• the oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and di( ⁇ -hydroperfluorohexanoyl) peroxide and di( di( ⁇ -hydro-dodecafluoroheptanoyl) peroxide, di( ⁇ -hydro-tetradecafluorooctanoyl) peroxide, di( ⁇ -hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluparyl) peroxide, di(perfluorohexanoyl) peroxide
• the water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, or sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, or percarbonic acid, t-butyl permaleate, or t-butyl hydroperoxide.
• a reducing agent such as sulfites may also be included, and the amount used may be 0.1 to 20 times that of the peroxide.
• the amount of polymerization initiator to be added is not particularly limited, but it is sufficient to add an amount at least to the extent that the polymerization rate does not decrease significantly (for example, a few ppm relative to the water concentration) all at once at the beginning of the polymerization, or gradually or continuously.
• the upper limit is the range in which the polymerization reaction heat can be removed from the equipment surface.
• Surfactants that can be used include nonionic surfactants, anionic surfactants, cationic surfactants, etc., and fluorine-based surfactants such as those used in International Publication No. 2000/029479, U.S. Patent Application Publication No. 2007/0015865, and JP 2014-540475 can also be used.
• the amount added (relative to the solvent) is preferably 10 ppm by mass to 20% by mass, more preferably 10 ppm by mass to 10% by mass, even more preferably 10 ppm by mass to 7% by mass, and particularly preferably 50 ppm by mass to 5% by mass.
• a reactive emulsifier may also be used as the surfactant.
• the reactive emulsifier is not particularly limited as long as it is a compound having at least one unsaturated bond and at least one hydrophilic group, and examples thereof include CH 2 ⁇ CFCF 2 OCF(CF 3 )CF 2 OCF(CF 3 )COONH 4 , CH 2 ⁇ CFCF 2 CF(CF 3 )OCF 2 CF 2 COONH 4 , and CF 2 ⁇ CFOCF 2 CF(CF 3 )OCF(CF 3 )COONH 4 .
• the amount of the emulsifier added is preferably 10 to 5000 ppm by mass, more preferably 50 to 5000 ppm by mass.
• a polymer of a compound having one or more unsaturated bonds and one or more hydrophilic groups may be used instead of a surfactant.
• a polymer of a compound having one or more unsaturated bonds and one or more hydrophilic groups examples include homopolymers of compounds such as CH 2 ⁇ CFCF 2 OCF(CF 3 )CF 2 OCF(CF 3 )COONH 4 , CH 2 ⁇ CFCF 2 CF(CF 3 )OCF 2 CF 2 COONH 4 , and CF 2 ⁇ CFOCF 2 CF(CF 3 )OCF(CF 3 )COONH 4 .
• the amount added (relative to the solvent) is preferably 10 ppm by mass to 10% by mass, more preferably 50 ppm by mass to 5% by mass, and even more preferably 50 ppm by mass to 2% by mass.
• the aqueous medium is preferably a medium that does not have chain transfer properties.
• examples of the aqueous medium include water, a mixture of water and a water-soluble organic solvent, or a mixture of water and a non-water-soluble organic solvent.
• the polymerization may also be carried out in the presence of a chain transfer agent.
• iodine compounds or bromine compounds may also be used as the chain transfer agent.
• the polymerization method using an iodine compound or bromine compound includes a method of carrying out emulsion polymerization in an aqueous medium under pressure in the presence of an iodine compound or bromine compound in a substantially oxygen-free state (iodine transfer polymerization method).
• iodine compound or bromine compound to be used include, for example, compounds represented by the general formula: R21IxBr y (wherein x and y are each an integer of 0 to 2 and satisfy 1 ⁇ x+y ⁇ 2, and R 21 is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom).
• R21IxBr y wherein x and y are each an integer of 0 to 2 and satisfy 1 ⁇ x+y ⁇ 2, and R 21 is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom.
• Examples of the iodine compound and the bromine compound include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF 2 Br 2 , BrCF 2 CF 2 Br, CF 3 CFBrCF 2 Br, CFClBr 2 , BrCF
• 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, etc.
• the polymerization temperature, polymerization pressure, and polymerization time vary depending on the type of solvent and polymerization initiator, but may be -15 to 150°C, atmospheric pressure to 12 MPa, and 1 to 24 hours.
• the polymerization temperature is preferably 30 to 95°C.
• the polymerization temperature is preferably 0 to 100°C, and more preferably 10 to 95°C.
• a crosslinkable composition can be prepared by mixing the above-mentioned polymer blend with at least one selected from the group consisting of inorganic nitrides, organic tin compounds, compounds that generate ammonia, and crosslinking agents.
• An article (crosslinked product) can be obtained by crosslinking the above-mentioned polymer blend and the crosslinkable composition containing at least one selected from the group consisting of inorganic nitrides, organic tin compounds, compounds that generate ammonia, and crosslinking agents.
• the inorganic nitride is not particularly limited, but examples thereof include silicon nitride (Si 3 N 4 ), lithium nitride, titanium nitride, aluminum nitride, boron nitride, vanadium nitride, zirconium nitride, etc. Among these, silicon nitride is preferable because nano-sized fine particles can be supplied.
• Organotin compounds include tetraphenyltin and triphenyltin.
• Urea derivatives include biurea, thiourea, urea hydrochloride, and biuret.
• Organic ammonium salts include ammonium salts of non-fluorine-based carboxylic or sulfonic acids, such as ammonium benzoate, ammonium adipate, and ammonium phthalate.
• inorganic ammonium salts include compounds described in JP-A-9-111081, such as ammonium sulfate, ammonium carbonate, ammonium nitrate, and ammonium phosphate.
• ammonia-generating compounds include acetaldehyde ammonia, hexamethylenetetramine, formamidine, formamidine hydrochloride, formamidine acetate, t-butyl carbamate, benzyl carbamate, and phthalamide.
• crosslinking agents include crosslinking agents used in peroxide crosslinking, polyol crosslinking, polyamine crosslinking, triazine crosslinking, oxazole crosslinking, imidazole crosslinking, and thiazole crosslinking.
• the crosslinking agent used in peroxide crosslinking may be any organic peroxide that can easily generate peroxy radicals in the presence of heat or an oxidation-reduction system.
• Specific examples include 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butyl peroxide (Perbutyl D), t-butylcumyl peroxide (Perbutyl C), dicumyl peroxide (Percumyl D, Percumyl D-40, Percumyl D-40MB(T)), ⁇ , ⁇ -bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Perhexa 25B, Perhexa 25B-40), ), 2,5-dimethyl-2,5-di(t-buty
• triallyl cyanurate triallyl isocyanurate (TAIC), triacryl formal, triallyl trimellitate, N,N'-n-phenylene bismaleimide, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalate amide, triallyl phosphate, bismaleimide, fluorinated triallyl isocyanurate (1,3,5-tris(2,3,3-trifluoro-2-propenyl)-1,3,5-triazine 2,4,6-trione), tris(diallylamine)-S-triazine, triallyl phosphite, N,N-diallylacrylamide, and 1,6-divinyldodecafluorohexane.
• crosslinking assistant used together with the peroxide crosslinking agent is represented by the general formula (31): (wherein, six R 31 are each independently H, a halogen atom, or an optionally halogenated group having 1 to 5 carbon atoms which may have an ether bond inserted, and Z 31 is an optionally halogenated linear or branched alkylene group, cycloalkylene group, or (per)fluoropolyoxyalkylene group having 1 to 18 carbon atoms which optionally contains a heteroatom).
• the compound represented by the general formula (31) includes a compound represented by the general formula (32): (wherein j is an integer of 2 to 10, preferably an integer of 4 to 8, and each of the four R 32 is independently H, F, or an alkyl group or (per)fluoroalkyl group having 1 to 5 carbon atoms), a compound represented by general formula (33): (wherein, Y 31 is each independently F, Cl or H, Y 32 is each independently F, Cl, H or OR 33 (wherein R 33 is a branched or linear alkyl group which may be partially, substantially or completely fluorinated or chlorinated), Z 33 is an optionally fluorinated divalent group having 2 to 10 carbon atoms which may have an ether bond inserted therein, preferably Z 33 is a -(CF 2 ) m - group where m is an integer of 3 to 5, and the compound represented by general formula (33) is preferably F 2 C ⁇ CF-O-(CF 2 ) 5 -O-CF ⁇ CF 2 ) ,
• crosslinking agent or the crosslinking assistant used together with the peroxide crosslinking agent may be a crosslinking agent represented by the general formula (35):
• R 35 to R 37 are each independently a hydrogen atom, a fluorine atom, an alkyl group, a fluorinated alkyl group, or a substituted or unsubstituted aryl group, and at least one of R 35 to R 37 is a fluorine atom or a group containing a fluorine atom.
• m is an integer of 1 to 5. When m is 2 or more, m R 35 to R 37 may be the same or different. The hydrogen atom of the benzene ring may be substituted.
• m it is preferable to have two or more of such structures.
• the compound having the structure represented by general formula (36) includes compounds represented by general formula (36):
• R 35 to R 37 are as defined above.
• R 38 is a single bond, -SO 2 -, -O-, -S-, -CO-, a heteroatom-containing group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group.
• m is an integer of 1 to 5. These groups may be fluorinated in part or in whole.
• the heteroatom-containing group is not particularly limited as long as it is a divalent group containing a heteroatom.
• heteroatoms include an oxygen atom, a nitrogen atom, a sulfur atom, a boron atom, and a phosphorus atom.
• Cross-linking agents used in polyol cross-linking include polyhydric alcohol compounds such as bisphenol A and bisphenol AF.
• Cross-linking agents used in polyamine cross-linking include polyamine compounds such as hexamethylenediamine carbamate, N,N'-dicinnamylidene-1,6-hexanediamine, and 4,4'-bis(aminocyclohexyl)methane carbamate.
• Crosslinking agents used for oxazole crosslinking, imidazole crosslinking, and thiazole crosslinking include those represented by the general formula (41):
• R 41 represents -SO 2 -, -O-, -CO-, an alkylene group having 1 to 6 carbon atoms, a perfluoroalkylene group having 1 to 10 carbon atoms or a single bond, or
• R 42 and R 43 is -NH 2 and the other is -NHR 44 , -NH 2 , -OH or -SH
• R 44 is a hydrogen atom, a fluorine atom or a monovalent organic group, preferably R 42 is -NH 2 and R 43 is -NHR 44.
• Specific preferred examples of the alkylene group having 1 to 6 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group and a hexylene group, and examples of the perfluoroalkylene group having 1 to 10 carbon atoms include
• R 41 is as described above, and R 45 is each independently any of the following groups.
• n is an integer of 1 to 10
• a bisamidooxime-based crosslinking agent represented by the general formula (45): HN CR 45 R 46 wherein R 45 is selected from the group consisting of H, NH 2 , and NHR 47 ; R 46 is selected from the group consisting of Ph, SO 2 H, NR 48 R 49 , 2-pyridine, and CH 2 CONH 2 ; R 47 is selected from the group consisting of Ph, NH 2 , and CN; R 48 is selected from the group consisting of H, NHPh, CH 2 CONH 2 , a straight chain alkyl group having 1 to 8 carbon atoms, and a branched alkyl group having 1 to 8 carbon atoms; and R 49 is selected from the group consisting of Ph, COOC(CH 3 ) 3 , NH 2 , CH 2 COOH, CSNH 2 , CNHNH 3 + Cl ⁇ , p-phenylCN, and COPh).
• the crosslinking agent may be a compound represented by the general formula (46): X 41 -(CH 2 ) n -R 50 -(CH 2 ) m -X 41 (wherein X 41 is each independently an alkyne group, a nitrile group, or Y 41 P N 3 (Y 41 is SO, SO 2 , C 6 H 4 or CO, and p is 0 or 1), n and m are independently an integer of 1 to 4, and R 50 is i) a fluoroalkylene group having 3 to 10 carbon atoms, ii) a fluoroalkoxysilane group having 3 to 10 carbon atoms; iii) a substituted arylene group; iv) oligomers containing copolymerized units of vinylidene fluoride and perfluoro(methyl vinyl ether); v) oligomers containing copolymerized units of vinylidene fluoride and hexafluoropropylene; vi)
• Particularly preferred crosslinking agents include compounds having multiple 3-amino-4-hydroxyphenyl groups or 3-amino-4-mercaptophenyl groups, or compounds represented by the general formula (47):
• R 41 , R 42 and R 43 are as defined above
• specific examples thereof include 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (general name: bis(aminophenol) AF), 2,2-bis(3-amino-4-mercaptophenyl)hexafluoropropane, tetraaminobenzene, bis-3,4-diaminophenylmethane, bis-3,4-diaminophenyl ether, 2,2-bis(3,4-diaminophenyl)hexafluoropropane, 2,2-bis[3-amino-4-(N-phenylamino)phenol], and the like.
• crosslinking agent 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane is preferred from the standpoint of heat resistance, steam resistance, amine resistance, and good crosslinking properties.
• the content of at least one selected from the group consisting of inorganic nitrides, organic tin compounds, compounds that generate ammonia, and crosslinking agents is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, particularly preferably 0.3 parts by mass or more, preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 2.0 parts by mass or less, and particularly preferably 1.0 parts by mass or less, relative to 100 parts by mass of the polymer blend.
• the crosslinkable composition may contain other components in addition to the crosslinking agent.
• ingredients include, for example, fillers.
• Fillers include imide-based fillers with an imide structure such as polyimide, polyamideimide, and polyetherimide; organic fillers made of engineering plastics such as polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherketone, and polyoxybenzoate; metal oxide fillers such as silicon oxide, aluminum oxide, and yttrium oxide; metal carbides such as silicon carbide and aluminum carbide; metal nitride fillers such as silicon nitride and aluminum nitride; and inorganic fillers such as carbon black, aluminum fluoride, and carbon fluoride.
• imide-based fillers with an imide structure such as polyimide, polyamideimide, and polyetherimide
• organic fillers made of engineering plastics such as polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherketone, and polyoxybenzoate
• carbon black aluminum oxide, silicon oxide, yttrium oxide, silicon carbide, silicon nitride, polyimide, and carbon fluoride are preferred in terms of their shielding effect against various plasmas.
• the above inorganic and organic fillers may be used alone or in combination of two or more.
• compositions such as processing aids, plasticizers, and colorants, can be blended as necessary, and one or more commonly used crosslinking agents or crosslinking assistants different from those mentioned above may also be blended.
• the crosslinkable composition may contain an organic basic compound, such as octadecylamine of formula CH 3 (CH 2 ) 17 -NH 2 ; Erucamide, of formula: H 2 N—C(O)—(CH 2 ) 11 —CH ⁇ CH—(CH 2 ) 7 CH 3 ; Oleamide of formula: H 2 N—C(O)—(CH 2 ) 7 —CH ⁇ CH—(CH 2 ) 7 CH 3 ; Hexamethylenediamine of formula: H 2 N—(CH 2 ) 6 —NH 2 Examples of such aryl ethers include 1,8-diazabicycloundec-7-ene (DBU).
• DBU 1,8-diazabicycloundec-7-ene
• the crosslinkable composition can be prepared by mixing the polymer blend and other components such as the crosslinking agent. Mixing can be carried out using a conventional polymer processing machine, such as an open roll, a Banbury mixer, a kneader, or an internal mixer.
• a conventional polymer processing machine such as an open roll, a Banbury mixer, a kneader, or an internal mixer.
• crosslinkable composition can be suitably used as a molding material for obtaining articles by crosslinking and molding.
• the article of the present disclosure can be obtained by crosslinking the above-mentioned crosslinkable composition.
• the article of the present disclosure has an appropriate hardness, a small compression set at high temperatures, and is unlikely to become large even after use under harsh conditions.
• the present disclosure also provides an article having a compression set of 50% or less measured after being left at 300°C for 70 hours, a compression set of less than 50% measured after being left at 200°C for 70 hours and then at 70°C for 70 hours, and a hardness of 65 or more measured according to ASTM D2240.
• the article of the present disclosure has a moderate hardness, a small compression set at high temperatures, and is unlikely to become large even after use under harsh conditions.
• the article of the present disclosure characterized by the compression set and hardness preferably contains a polymer.
• the polymer the above-mentioned polymer blend is preferable.
• the hardness of the article (Shore A, peak value) is preferably 65 or more, and more preferably 67 or more.
• the upper limit of the hardness is not particularly limited, but may be 90 or less, or 80 or less.
• the hardness of the article can be measured in accordance with JIS K6253.
• the article of the present disclosure has an appropriate hardness. Therefore, when the article of the present disclosure is used, for example, as a sealing material, the article is unlikely to be crushed even when tightly fastened, and is unlikely to crack even when used at high temperatures. If the hardness of the article is too low, it may be difficult to fasten tightly, or it may be prone to cracking when used at high temperatures. If the hardness is too high, it may be difficult to compress the article, making it difficult to obtain excellent sealing properties.
• the compression set (300°C) of the article measured after leaving it at 300°C for 70 hours is preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, and even more preferably 35% or less.
• the compression set (300°C) can be calculated by compressing the article at a compression rate of 25%, leaving it at 300°C for 70 hours, releasing the compression, leaving it at 23°C for 30 minutes, and then measuring the thickness of the article before and after compression.
• the articles disclosed herein have low compression set even when used at high temperatures exceeding 300°C.
• the compression set (200°C) of the article measured after leaving it at 200°C for 70 hours and then at 70°C for 70 hours is preferably less than 50%, more preferably 45% or less, and even more preferably 40% or less.
• the compression set (200°C) can be calculated by compressing the article at a compression rate of 25%, leaving it at 200°C for 70 hours, leaving it at 70°C for 270 hours, releasing the compression, leaving it at 20°C for 30 minutes, and then measuring the thickness of the article after compression.
• the article of the present disclosure is unlikely to suffer from large compression set even after use under harsh conditions.
• the sealing material may be used in a compressed state at temperatures of 200°C or higher while the semiconductor manufacturing equipment is in operation.
• the sealing material remains compressed and is slowly cooled to room temperature, and then left at room temperature. Therefore, the sealing material is required to have properties that enable it to withstand use under such harsh conditions.
• the article of the present disclosure has excellent high-temperature and low-temperature sealing properties and can withstand use under such harsh conditions.
• Methods for obtaining articles from crosslinkable compositions include a method in which a preform is obtained by molding the crosslinkable composition as a molding material, and then crosslinking the preform.
• a preform can be obtained from a crosslinkable composition by a conventional method, such as a method of heating and compressing in a mold, a method of forcing into a heated mold, or a method of extruding with an extruder.
• a conventional method such as a method of heating and compressing in a mold, a method of forcing into a heated mold, or a method of extruding with an extruder.
• extrusion products such as hoses and electric wires
• articles can be obtained by heating and crosslinking using steam or the like after extrusion.
• the above crosslinking is called primary crosslinking, and can be carried out in the order of primary crosslinking and secondary crosslinking.
• Primary crosslinking is preferably carried out at 150-250°C for 5-120 minutes, and more preferably at 170-200°C for 5-60 minutes. Any known crosslinking method can be used for crosslinking, such as press crosslinking.
• the secondary crosslinking is preferably carried out at 250-320°C for 2-48 hours, and more preferably at 280-310°C for 5-24 hours.
• the secondary crosslinking may also be carried out at 180-320°C for 2-24 hours, or at 190-310°C for 5-20 hours. Temperature changes may be made within this temperature range.
• a known crosslinking means may be used, such as oven crosslinking.
• Crosslinking may be carried out, for example, in an air atmosphere or a nitrogen atmosphere.
• the article of the present disclosure can be suitably used as a sealing material for semiconductor manufacturing equipment that requires heat resistance, particularly for semiconductor manufacturing equipment that is exposed to high-density plasma.
• the sealing material include O-rings, square rings, gaskets, packing, oil seals, bearing seals, and lip seals.
• it can be used for various polymer products used in semiconductor manufacturing equipment, such as diaphragms, tubes, hoses, various rubber rolls, belts, etc. It can also be used as a coating material or a lining material.
• the semiconductor manufacturing equipment referred to in this disclosure is not limited to equipment specifically for manufacturing semiconductors, but broadly includes all manufacturing equipment used in the semiconductor field that requires a high degree of cleanliness, such as equipment for manufacturing liquid crystal panels and plasma panels, and examples of such equipment include the following:
• the article disclosed herein exhibits excellent performance as a sealing material for, for example, CVD equipment, plasma etching equipment, reactive ion etching equipment, ashing equipment, or excimer laser exposure equipment.
• the melting point of the polymer blend is 310 to 320° C.;
• the polymer blend is provided, wherein the content of the crystalline fluoropolymer (b) in the polymer blend is 4.0 to 15.0% by mass, based on the total mass of the fluoroelastomer (a) and the crystalline fluoropolymer (b).
• a polymer blend according to the first aspect wherein the polymer blend has a Mooney viscosity at 170° C. of 70 to 120.
• a polymer blend according to the first or second aspect wherein the content of nitrogen-containing crosslinking sites in the polymer blend is 0.5 to 3.0 mol %, relative to 100 mol % of all monomer units constituting the fluoroelastomer (a) and the crystalline fluoropolymer (b).
• a polymer blend according to any of the first to third aspects wherein the content ratio of tetrafluoroethylene units and fluoroalkyl vinyl ether units in the polymer blend is 50/50 to 70/30 in terms of a molar ratio (tetrafluoroethylene units/fluoroalkyl vinyl ether units).
• the fluoroalkyl vinyl ether units in the fluoroelastomer (a) are perfluoro(methyl vinyl ether) units.
• a polymer blend according to any of the first to fifth aspects wherein the fluoroelastomer (a) and the crystalline fluoropolymer (b) contain monomer units having nitrogen-containing crosslinkable groups.
• the polymer blend according to any one of the first to sixth aspects is provided by a production method in which an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) is prepared, and the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous dispersion are coagulated.
• (1-1) preparing an aqueous dispersion containing a fluoroelastomer (a) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-2) preparing an aqueous dispersion containing a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group in the presence of an aqueous medium; (1-3) preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) by mixing an aqueous dispersion containing a fluoroelastomer (a) and an aqueous dispersion containing a crystalline fluoropolymer (b); (1-4) There is provided a
• a ninth aspect of the present disclosure there is provided a polymer blend according to any one of the first to eighth aspects, wherein the content of the nitrogen-containing crosslinking moiety in the fluoroelastomer (a) is 0.5 to 3.0 mol % when the total monomer units constituting the fluoroelastomer (a) is taken as 100 mol %.
• a polymer blend according to any one of the first to ninth aspects in which the content of the nitrogen-containing crosslinking site in the crystalline fluoropolymer (b) is 0.5 to 3.0 mol % when the total monomer units constituting the crystalline fluoropolymer (b) is taken as 100 mol %.
• tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing a crystalline fluoropolymer (b), and then (2-2) preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of the crystalline fluoropolymer (b) and an aqueous medium; (2-3) There is provided a polymer blend according to any one of the first to seventh aspects, which is obtained by a production method comprising coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b) in the aqueous disper
• a crosslinkable composition comprising the polymer blend according to any one of the first to eleventh aspects, and at least one selected from the group consisting of an inorganic nitride, an organotin compound, an ammonia-generating compound, and a crosslinking agent.
• an inorganic nitride an organotin compound
• an ammonia-generating compound an ammonia-generating compound
• a crosslinking agent e.g., an article obtainable by crosslinking the crosslinkable composition.
• the compression set measured after standing at 300°C for 70 hours is 50% or less, The compression set measured after leaving the material at 200° C. for 70 hours and then at 70° C.
• a method for producing a polymer blend according to any one of the first to seventh and eleventh aspects comprising the steps of: (2-1) In the presence of an aqueous medium, tetrafluoroethylene and a monomer having a nitrogen-containing crosslinkable group are polymerized to prepare an aqueous dispersion containing a crystalline fluoropolymer (b), and then (2-2) preparing an aqueous dispersion containing a fluoroelastomer (a) and a crystalline fluoropolymer (b) by polymerizing tetrafluoroethylene, a fluoroalkyl vinyl ether, and a monomer having a nitrogen-containing crosslinkable group in the presence of the crystalline fluoropolymer (b) and an aqueous medium; (2-3) There is provided a production method for obtaining the polymer blend by coagulating the fluoroelastomer (a) and the crystalline fluoropolymer (b), and then (2-2) preparing an
• Mooney Viscosity The Mooney viscosity (ML(1+20)) of the polymer blend and the fluoroelastomer was measured at 170° C. in accordance with JIS K6300 using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES.
• the glass transition temperature of the polymer blend was determined by obtaining a DSC curve using a differential scanning calorimeter (X-DSC7000, manufactured by Hitachi High-Tech Science Corporation) by heating 3 mg of a sample at 20° C./min, and determining the temperature as the midpoint between two intersections between an extension line of the baseline before and after the second-order transition of the DSC curve and a tangent line at the inflection point of the DSC curve.
• X-DSC7000 differential scanning calorimeter
• the melting point of the polymer blend was measured by weighing out about 10 mg of the polymer blend that had not been heated to a temperature of 300° C. or higher, placing it in a dedicated aluminum pan, and using a TG/DTA (thermogravimetric differential thermal analyzer).
• the aluminum pan was heated in an air atmosphere in a temperature range from 25° C. to 600° C. at a rate of 10° C./min to obtain a DTA curve, and the temperature corresponding to the peak in the obtained DTA curve was identified as the melting point of the polymer blend.
• the presence or absence of a melting point of the fluoroelastomer was also confirmed using the method for measuring the melting point of the polymer blend.
• N.D indicates that no clear peak was identified in the DTA curve.
• CF2 CFOCF2CF ( CF3 ) OCF2CF2CN (CNVE) was charged, followed by charging TFE to a pressure of 0.29MPa, and the pressure and temperature in the vessel were maintained. 3.0g of ammonium persulfate (APS) was charged as a polymerization initiator.
• APS ammonium per
• TFE was charged so that the reaction pressure was constant at 0.36 MPa, and a total of 0.45g of CNVE was continuously charged until 42.0g of TFE was added.
• the pressure in the tank was reduced to 0.26 MPa, and then 115g of PMVE was charged.
• a total of 17.4 g of CNVE was continuously charged.
• TG/DTA measurements of the resulting polymer blend showed a melting point of 317.5°C, and the weight loss rate indicated that the content of crystalline fluoropolymer (b) was 5.2 wt%.
• DSC measurements also showed that the glass transition temperature was -2.6°C.
• the Mooney viscosity was 111.
• Example 9 995g of the aqueous dispersion of fluoroelastomer (a) and 846g of the aqueous dispersion of fluoropolymer (b1) were introduced into a vessel equipped with a stirrer in advance to prepare a mixed aqueous dispersion.
• the prepared mixed aqueous dispersion was coagulated with nitric acid water, washed with water, and vacuum dried at 70°C for 24 hours to obtain 220g of a polymer blend.
• the TG/DTA measurement of the obtained polymer blend showed a melting point of 318°C, and the content of crystalline fluoropolymer (b) was found to be 4.7wt% from the weight loss rate.
• the glass transition temperature was found to be -5.0°C from the DSC measurement.
• the Mooney viscosity was also 86.

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