Curable fluoropolymer composition containing metal fluoride particles and articles therefrom

Abstract

Curable fluoropolymer compositions comprising an amorphous fluoropolymer and metal fluoride particles, wherein the particles are substantially unsurfaced and the metal of the metal fluoride comprises at least one of alkaline earth metals, Group III transition metals, and lanthanide metals, are described herein. Cured articles produced from curable fluoropolymer compositions are also described.

Description

Technical Field

[0001] A curable composition containing particles of an amorphous fluoropolymer and a metal fluoride, and a cured article thereof are described.

Summary of the Invention

[0002] It is desirable to identify fluorinated elastomers having good chemical performance characteristics and improved performance in plasma etching.

[0003] In one aspect, a curable fluoropolymer composition containing an amorphous fluoropolymer and particles of a metal fluoride is described, and the metal of the metal fluoride includes at least one of an alkaline earth metal, a Group III transition metal particle, and a lanthanide.

[0004] In another aspect, a cured article containing a fluoroelastomer and particles of a metal fluoride is described, the particles are substantially not surface-treated, and the metal of the metal fluoride includes at least one of an alkaline earth metal, a Group III transition metal particle, and a lanthanide.

[0005] In another aspect, it is to provide a curable fluoropolymer composition containing an amorphous fluoropolymer and particles of a metal fluoride, wherein the particles are substantially not surface-treated, and the metal of the metal fluoride includes at least one of an alkaline earth metal, a Group III transition metal particle, and a lanthanide, and then curing the curable composition, a method for manufacturing an article is described.

[0006] The above summary of the present disclosure is not intended to describe each embodiment. Details of one or more embodiments of the present invention are also described in the following description. Other features, objects, and advantages will become apparent from the description and the claims.

Modes for Carrying Out the Invention

[0007] As used herein, the terms "a", "an", and "the" are used interchangeably and mean one or more. The term "and / or" is used to indicate that one or both of the stated events may occur, e.g., A and / or B includes (A and B) as well as (A or B). "Main chain" refers to the main continuous chain of a polymer. "Crosslinking" refers to connecting two preformed polymer chains using chemical bonds or chemical groups. "Curing site" refers to a functional group that may be involved in crosslinking. "Copolymerized" means that monomers polymerize together to form a polymer main chain. As used herein, "latex" refers to a dispersion of polymer particles in an aqueous continuous phase. "Monomer" is a molecule that can undergo polymerization and then form part of the basic structure of a polymer. "Organic" has its general meaning in the art, e.g., organic compounds are carbon-containing compounds with some exceptions / exclusions, including binary compounds such as carbides, carbon monoxide, carbon disulfide; ternary compounds such as metal cyanides, phosgene, carbonyl sulfide, and metal carbonates such as calcium carbonate. "Perfluorinated" means a group or compound derived from a hydrocarbon in which all hydrogen atoms have been replaced by fluorine atoms. However, perfluorinated compounds may further contain atoms other than fluorine and carbon atoms, such as oxygen atoms, chlorine atoms, bromine atoms, and iodine atoms. "Polymer" refers to a macrostructure having a number average molecular weight (Mn) of at least 30,000 daltons, at least 50,000 daltons, at least 100,000 daltons, at least 300,000 daltons, at least 500,000 daltons, at least 750,000 daltons, at least 1,000,000 daltons, or even at least 1,500,000 daltons, and not so high as to cause premature gelation of the polymer.

[0008] Furthermore, in this specification, the description of a range by endpoints includes all numbers included within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0009] Furthermore, in this specification, the description of "at least one" includes all numbers of 1 or more (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0010] The present disclosure relates to an amorphous fluoropolymer composition containing metal fluoride particles. These amorphous fluoropolymer compositions can then be cured to form fluoroelastomer articles.

[0011] The metal fluoride particles of the present disclosure contain a metal, and the metal is an alkaline earth metal (i.e., Be, Mg, Ca, Sr, Ba, and Ra), a Group III transition metal (i.e., Sc and Y), and / or a lanthanide series metal (i.e., those having atomic numbers 57 to 71). In one embodiment, the metal is an alkaline earth metal. In one embodiment, the metal is a Group III transition metal. In yet another embodiment, the metal is a lanthanide series metal. Exemplary metal fluorides include calcium fluoride, magnesium fluoride, yttrium fluoride, and ytterbium fluoride. In one embodiment, the metal fluoride is not water-soluble, meaning that the metal fluoride has a solubility of less than 0.50, 0.40, 0.30, 0.20, 0.10, 0.05, or even 0.01 g per 100 g of water at ambient pressure (e.g., 1 atm) and 25 °C. For example, the solubility of LiF is 0.13 g / 100 mL at 25 °C, ZrF4 is 1.388 g / 100 mL at 25 °C, and AlF3 is 0.559 g / 100 mL at 25 °C, which is from the CRC Handbook of Chemistry and Physics, 47 thEdition, Weast, Robert C., Ed., page B-149~B-252, The Chemical Rubber Company, Cleveland: 1966 and The Merck Index, 9 th ed., Merck & Co., Rahway, NJ, 1976, pages 47 and 722 etc. can be found in reference books such as these.

[0012] The metal fluoride particles of the present disclosure are not particularly limited in shape. In one embodiment, the metal fluoride particles are essentially spherical or elliptical, which means that when the particles are enlarged in a two-dimensional image, they are generally rounded and do not contain sharp corners or edges.

[0013] The particle size of the metal fluoride particles can be determined based on methods known in the art, such as microscopy, electrical impedance method, or light scattering method.

[0014] In one embodiment, the particles are essentially micron-sized, and the particles have an average diameter of at least 750 nm, 1 micron, 2 microns, 5 microns, 10 microns, or even 20 microns, and less than 50, 100, 150, 200, 250, 300, 400, 500, 600, 800, 900, or even 1000 microns.

[0015] In one embodiment, the particles have an average diameter of less than 500, 400, 300, 200, or even 100 nm.

[0016] In one embodiment, the particles are essentially nano-sized, having an average diameter of at least 3 nm, 5 nm, 8 nm, 10 nm, 15 nm, or even 20 nm, and at most about 25, 30, 50, or even 100 nm.

[0017] In one embodiment, the metal fluoride particles contain a single metal fluoride and are essentially pure, but the particles may contain small amounts (e.g., less than 20, 10, 5, 1, 0.5, 0.3, or even 0.2 wt%) of other metals such as copper or phosphorus.

[0018] In one embodiment, the particles include a combination of metal fluorides such as a combination of ytterbium fluoride and magnesium fluoride.

[0019] The metal fluoride particles of the present disclosure are not surface-treated with an organic moiety, meaning that the surface of the particles contains little or no organic compounds (such as via ionic bonds, hydrogen bonds, van der Waals forces, or covalent bonds) bonded to the particles. In many cases, metal-containing particles used in plasma applications are surface-treated to improve their performance. Silylating agents, silicone oils, or silane coupling agents are some of the treatments used to modify the particle surface. Examples of silylating agents are, for example, trimethylchlorosilane, dimethyldichlorosilane, hexamethyldisilazane, N,O-bis(trimethylsilyl)acetamide, N-trimethylsilylacetamide, N,N'-bis(trimethylsilyl)urea, N-trimethylsilyldiethylamine, N-trimethylsilylimidazole, t-butyldimethylchlorosilane, and the like. An example of a silicone oil is dimethyl silicone oil. Examples of silane coupling agents are, for example, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-(methacryloyloxypropyl)trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and the like. In the present disclosure, it has been discovered that metal fluoride particles that are substantially not surface-treated can function well under plasma etching conditions. In one embodiment, the weight of the organic moiety on the surface of the metal fluoride particles compared to the weight of the metal fluoride particles is less than 20, 10, 5, 1, 0.5, 0.1, 0.05, or even 0.01%, or even contains no detectable organic moiety on the surface.

[0020] The metal fluoride particles in the curable composition are used in an amount of at least 0.1, 0.5, 1, 2, 4, 5, 8, 10, or even 12% by weight and are up to 10, 15, 20, 25, or even 30% by weight when compared to the weight of the curable composition.

[0021] The present disclosure provides metal fluoride particles having an amorphous fluoropolymer. As used herein, an amorphous fluoropolymer refers to a polymer having no crystalline characteristics detectable by DSC (differential scanning calorimetry). When analyzed by DSC, the amorphous fluoropolymer has no melting point or melting transition having an enthalpy greater than 2 millijoules / g by DSC.

[0022] The amorphous fluoropolymers of the present disclosure are highly fluorinated, meaning that at least 60%, 70%, 75%, 90%, 95%, or even 99% of the carbon-hydrogen bonds of the amorphous fluoropolymer are replaced by carbon-fluorine bonds. In one embodiment, the amorphous fluoropolymer is perfluorinated, i.e., the polymer contains no C-H bonds and contains C-F bonds except at the sites where polymerization is initiated or terminated.

[0023] The amorphous fluoropolymers of the present disclosure are derived from at least one fluorinated monomer. Exemplary fluorinated monomers include tetrafluoroethylene (TFE), vinyl fluoride (VF), vinylidene fluoride (VDF), hexafluoropropylene (HFP), pentafluoropropylene, trifluoroethylene, trifluorochloroethylene (CTFE), (per)fluorovinyl ethers (including perfluoroalkyl vinyl ethers and perfluoroalkoxy vinyl ethers), (per)fluoroalkyl ethers (including perfluoroalkyl allyl ethers and perfluoroalkoxy allyl ethers), perfluoroalkyl vinyl monomers, fluorinated alkoxides (such as hexafluoropropylene oxide), fluorinated styrenes, fluorinated siloxanes, and combinations thereof.

[0024] Suitable (per)fluoroalkyl vinyl monomers have the general formula: CF2=CF-O-Rf 5 or CH2=CH-O-Rf 5 [wherein, Rf 5 represents a perfluoroalkyl group having 1 to 10, or more preferably 1 to 5 carbon atoms]. Examples of perfluoroalkoxy vinyl ethers include the formula CF2=CF-O-Rf 6 [wherein, Rf 6 represents a perfluorinated aliphatic group which may contain one or more oxygen atoms and up to 12, 10, 8, 6, or more preferably 4 carbon atoms]. Specific examples of (per)fluorovinyl ethers include perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), perfluoro(n-propyl vinyl) ether (PPVE-1), perfluoro-2-propoxypropyl vinyl ether (PPVE-2), perfluoro-3-methoxy-n-propyl vinyl ether, perfluoro-2-methoxy-ethyl vinyl ether, and

Chemical formula

[0025] Suitable (per)fluoroalkyl allyl ether monomers have the general formula: CF2=CF-CF2-O-Rf 5 or CH2=CH-CF2-O-Rf 5 [wherein, Rf 5 represents a perfluoroalkyl group having 1 to 10, or more preferably 1 to 5 carbon atoms]. Examples of perfluoroalkoxy allyl ethers include the formula CF2=CF(CF2)-O-Rf 7 [wherein, Rf 7 represents a perfluorinated aliphatic group which may contain one or more oxygen atoms and up to 10, 8, 6, or more preferably 4 carbon atoms]. Specific examples of (per)fluoroallyl ethers include CF2=CF2-CF2-O-(CF2) n F [wherein, n is an integer of 1 to 5], and CF2=CF2-CF2-O-(CF2) x-O-(CF2) y -F [wherein x is an integer from 2 to 5 and y is an integer from 1 to 5] can be mentioned.

[0026] Furthermore, as is known in the art, a curing site monomer can be added during the polymerization, whereby the amorphous fluoropolymer comes to contain iodine, bromine and / or nitrogen-containing curing site groups, and thereafter can be used to crosslink the amorphous fluoropolymer composite.

[0027] In one embodiment, the iodine and bromine curing site groups are of the formula: CX2=CX(Z) [wherein (i) each X is independently H or F, and (ii) Z is I, Br, or R f -U [wherein U = I or Br and R f is an optionally O atom-containing perfluorinated or partially perfluorinated alkylene group]]. It can be derived from monomers. In addition, non-fluorinated bromo or iodo olefins such as vinyl iodide and allyl iodide can be used. Exemplary iodinated and brominated curing site groups can be derived from CH2=CHI, CF2=CHI, CF2=CFI, CH2=CHCH2I, CF2=CFCF2I, CH2=CHCF2CF2I, CH2=CHCF2CF2CH2CH2I, CH2=CH(CF2)4I, CH2=CH(CF2)4CH2CH2I, CH2=CH(CF2)6I, CH2=CH(CF2)6CH2CH2I, CF2=CFCH2CH2I, CF2=CFCF2CF2I, CF2=CFOCF2CF2I, CF2=CFOCF2CF2CH2CH2I, CF2=CFOCF2CF2CF2I, CF2=CFOCF2CF2CF2CH2CH2I, CF2=CFOCF2CF2CH2I, CF2=CFOCF2CF2CF2CH2I, CF2=CFCF2OCH2CH2I, CF2=CFO(CF2)3-OCF2CF2I, CH2=CHBr, CF2=CHBr, CF2=CFBr, CH2=CHCH2Br, CF2=CFCF2Br, CH2=CHCF2CF2Br, CF2=CFOCF2CF2Br, CF2=CFCl, CF2=CFCF2Cl, and mixtures thereof.

[0028] In one embodiment, the nitrogen-containing curing site group may include, for example, acetate, adipate, nitrile, amidine, imidate, amidoxime, amidrazone group, or a combination thereof.

[0029] Exemplary nitrogen-containing curing site groups are of the formula: CF2=CF-CF2-O-R f -CN, CF2=CFO(CF2) w CN, CF2=CFO[CF2CF(CF3)O] g (CF2) v OCF(CF3)CN, CF2=CF[OCF2CF(CF3)] k O(CF2) u CN [wherein w represents an integer from 2 to 12, g represents an integer from 0 to 4, k represents 1 or 2, v represents an integer from 0 to 6, u represents an integer from 1 to 6, and R f represents a perfluoroalkylene group or a divalent perfluoroether group], and can be derived from these mixtures. Specific examples include perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene), CF2=CFO(CF2)5CN, and CF2=CFO(CF2)3OCF(CF3)CN.

[0030] Alternatively, in addition to the curing site monomer, a polymerization initiator and / or a chain transfer agent can be used to generate terminal sites on the fluoropolymer, which can then be used to crosslink the amorphous fluoropolymer.

[0031] In one embodiment, the amorphous fluoropolymer composition contains at least 0.1, 0.5, 1, 2, or even 2.5 weight % of iodine, bromine, and / or nitrile groups, based on the total weight of the fluoropolymer. In one embodiment, the fluoropolymer contains 1, 2, 3, 5, or even 10 weight % or less of iodine, bromine, and / or nitrile groups, based on the total weight of the fluoropolymer.

[0032] In another embodiment, the amorphous fluoropolymer is substantially free of iodine, bromine, and / or nitrile curing sites, which means that the fluoropolymer contains less than 0.1, 0.05, 0.01, or even 0.005 weight % of I, Br, and C≡N, or even no I, Br, and C≡N, based on the weight of the amorphous fluoropolymer.

[0033] In one embodiment, the amorphous fluoropolymer is derived from the following copolymerized monomers: (i) perfluorinated olefins (such as TFE and / or HFP), (ii) perfluoro(alkyl vinyl ethers) such as perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), and perfluoro(butyl vinyl ether) and / or perfluoro(alkoxy vinyl ether) monomers such as CF2=CFO[CF2CF(CF3)O]2CF2CF2CF3, and (iii) structural units derived from monomers capable of donating crosslinkable groups (such as carboxyl (COOH) groups, alkoxycarbonyl (COOR) groups, cyano (CN) groups, iodine atoms, and bromide atoms, including those containing COOH groups, COOR groups, and CN groups).

[0034] In one embodiment, the amorphous fluoropolymer is derived from the following copolymerized monomers: (i) 40 to 90 mol% tetrafluoroethylene, (ii) 10 to 60 mol% perfluorovinyl ether, and (iii) 0 to 5 mol% of a monomer that provides a cure site. Such exemplary amorphous fluoropolymers include 50 to 75 mol% TFE, 25 to 50 mol% PMVE, and 0.1 to 20 mol% CF2=CFOCF2CF(CF3)OCF2CF2CN; 50 to 75 mol% TFE, 25 to 50 mol% PMVE, and 0.1 to 20 mol% CF2=CFOCF2CF2CF2OCF(CF3)CN; 60 to 85 mol% TFE, 15 to 40 mol% CF2=CF(OCF2CF(CF3))2OCF2CF2CF3, and 0.1 to 20 mol% / CF2=CFOCF2CF(CF3)OCF2CF2CN; 50 to 75 mol% TFE, 25 to 50 mol% PMVE, and 0.1 to 20 mol% CF2=CFOCF2CF(CF3)OCF2CF2I; 50 to 75 mol% TFE, 25 to 50 mol% PMVE, and 0.1 to 20 mol% CF2=CFOCF2CF2CF2OCF(CF3)I; and 60 to 85 mol% TFE, 15 to 40 mol% CF2=CF(OCF2CF(CF3))2OCF2CF2CF3, and 0.1 to 20 mol% / CF2=CFOCF2CF(CF3)OCF2CF2I.

[0035] In one embodiment, the amorphous fluoropolymer is derived from the following copolymerized monomers: (i) 30 to 90 mol% vinylidene fluoride, (ii) 15 to 40 mol% hexafluoropropylene, and (iii) 0 to 30 mol% tetrafluoroethylene.

[0036] The metal fluoride particles can be introduced into the amorphous fluoropolymer while in the liquid phase or powder phase. For example, the metal fluoride particles may be added during compounding with the amorphous fluoropolymer, or they may be present during the polymerization of the amorphous fluoropolymer latex, or added to the amorphous fluoropolymer latex prior to coagulation.

[0037] The curable fluoropolymer composition of the present disclosure can be cured using compounds and techniques known in the art. A curing agent can be added to the curable fluoropolymer composition to cure the amorphous fluoropolymer into a fluoroelastomer. Such curing agents are known in the art and include, for example, peroxides, bisaminophenols such as bisorthoaminophenol, adipates, amidines, acetates, triazine-forming curing agents (e.g., oniums such as ammonium, phosphonium, sulfonium, or iodonium), or combinations thereof. When curing an amorphous fluoropolymer with a peroxide curing agent, the fluoropolymer contains Br, I, and / or CN curing sites, and preferably the peroxide is an organic peroxide such as a tertiary butyl peroxide having a tertiary carbon atom bonded to peroxy oxygen.

[0038] Exemplary peroxides include benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,4-dichlorobenzoyl peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylchlorohexane, tert-butylperoxyisopropyl carbonate (TBIC), tert-butylperoxy 2-ethylhexyl carbonate (TBEC), tert-amylperoxy 2-ethylhexyl carbonate, tert-hexylperoxyisopropyl carbonate, carbonoperoxy acid, O,O’-1,3-propanediyl OO,OO’-bis(1,1-dimethylethyl) ester, tert-butylperoxybenzoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, laurel peroxide, and cyclohexanone peroxide. Other suitable peroxide curing agents are listed in U.S. Patent No. 5,225,504 (Tatsu et al.), which is incorporated herein by reference.

[0039] The amount of peroxide used is generally at least 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, or even 1.5 parts by weight, up to 2, 2.25, 2.5, 2.75, 3, 3.5, 4, 4.5, 5, or even 5.5 parts by weight per 100 parts by weight of the fluoropolymer.

[0040] The coagent is a reactive additive used to improve peroxide curing efficiency by reacting rapidly with radicals, potentially suppressing side reactions, and / or generating further crosslinking. The coagent forms radicals via hydrogen abstraction or addition of radicals from peroxides and can then react with the polymer via Br, I, and / or nitrile sites. The coagent is a polyfunctional polyunsaturated compound, known in the art, and includes allyl-containing cyanurates, isocyanurates, and phthalates, homopolymers of dienes, and copolymers of dienes and vinyl aromatics. A wide variety of useful coagents are commercially available, including di- and triallyl compounds, divinylbenzene, vinyltoluene, vinylpyridine, 1,2-cis-polybutadiene and their derivatives. Exemplary coagents include diallyl ether of glycerin, trialkyl phosphinic acid, diallyl adipate, diallyl melamine and triallyl isocyanurate (TAIC), tri(methyl)allyl isocyanurate (TMAIC), tri(methyl)allyl cyanurate, poly-triallyl isocyanurate (poly-TAIC), xylene-bis(diallyl isocyanurate) (XBD), N,N’-m-phenylenebismaleimide, diallyl phthalate, tris(diallylamine)-s-triazine, triallyl phosphite, 1,2-polybutadiene, ethylene glycol diacrylate, diethylene glycol diacrylate, and mixtures thereof. Exemplary partially fluorinated compounds containing two terminal unsaturated sites include CH2=CH-R f1 -CH=CH2 (wherein R f1 can be a perfluoroalkylene of 1 to 8 carbon atoms) and fluorine-containing TAIC (such as those disclosed in U.S. Patent No. 6191233 (Kishine et al.), incorporated herein by reference).

[0041] In one embodiment, the curable composition includes an amorphous fluoropolymer, a peroxide, and a co-agent, and the amount of co-agent used is generally at least 0.1, 0.5, or even 1 part by weight per 100 parts of the fluoropolymer, and at most 2, 2.5, 3, or even 5 parts by weight per 100 parts of the amorphous fluoropolymer.

[0042] When using a polyhydroxy compound to cure an amorphous fluoropolymer, typically, the fluoropolymer contains carbon-carbon double bonds and / or forms carbon-carbon double bonds along the polymer chain, and can form a fluoroelastomer. Polyhydroxy compounds for curing fluoropolymers are known in the art and include those disclosed in U.S. Patent Nos. 3,876,654 (Pattison) and 4,233,421 (Worm), both of which are incorporated herein by reference. Representative examples include aromatic polyhydroxy compounds, preferably any one of the following: di-, tri-, and tetrahydroxybenzenes, and bisphenols. Exemplary aromatic polyhydroxy compounds include 4,4'-hexafluoroisopropylidenebisphenol, more commonly known as bisphenol AF. Further useful examples include 4,4'-dihydroxydiphenyl sulfone (also known as bisphenol S), 4,4'-isopropylidenebisphenol (also known as bisphenol A), or 4,4'-(perfluoropropane-2,2-diyl)diphenol, dihydroxybenzophenone, hydroquinone, 2,4,6-trimercapto-S-triazine, 4,4'-thiodiphenol, and metal salts thereof.

[0043] Typically, a maximum of 2, 2.5, 3, 4, 4.5, or even 5% by weight of the polyhydroxy compound is used relative to the amorphous fluoropolymer.

[0044] In one embodiment, the curable composition may include an organic onium compound to assist in the crosslinking of the amorphous fluoropolymer and / or may be used to generate double bonds on the polymer via dehydrofluorination. Such organic onium compounds include quaternary ammonium hydroxides or salts, quaternary phosphonium hydroxides or salts, and ternary sulfonium hydroxides or salts.

[0045] Briefly, phosphonium and ammonium salts or compounds each contain a central atom of phosphorus or nitrogen that is covalently bonded to four organic moieties by carbon-phosphorus (or carbon-nitrogen) covalent bonds and is ionically bonded to an anion. These organic moieties may be the same or different.

[0046] Briefly, a sulfonium compound is a sulfur-containing organic compound in which at least one sulfur atom is covalently bonded to three organic moieties having 1 to 20 carbon atoms by carbon-sulfur covalent bonds and is ionically bonded to an anion. These organic moieties may be the same or different. The sulfonium compound may have two or more relatively positive sulfur atoms, for example, [(C6H5)2S + (CH2)4S + (C6H5)2]2Cl - and two of the carbon-sulfur covalent bonds may be between carbon atoms of a divalent organic moiety, i.e., the sulfur atom may be a heteroatom in a cyclic structure.

[0047] Organic onium compounds are known in the art, such as U.S. Patent No. 4,233,421 (Worm), U.S. Patent No. 4,912,171 (Grootaert et al.), U.S. Patent No. 5,086,123 (Guenthner et al.), and U.S. Patent No. 5,262,490 (Kolb et al.), and U.S. Patent No. 5,929,169, the descriptions of which are hereby incorporated by reference in their entirety. Another class of useful organic onium compounds includes those having one or more pendant fluorinated alkyl groups. Generally, the most useful fluorinated onium compounds are disclosed in U.S. Patent No. 5,591,804 (Coggio et al.).

[0048] Exemplary organic onium compounds include symmetric tetraalkylammonium salts having C3 - C6, asymmetric tetraalkylammonium salts having a total of 8 - 24 alkyl carbons, and benzyltrialkylammonium salts having a total of 7 - 19 alkyl carbons (e.g., tetrabutylammonium bromide, benzyltributylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium hydrogen sulfate, and tetrabutylammonium hydroxide, phenyltrimethylammonium chloride, tetrapentylammonium chloride, tetrapropylammonium bromide, tetrahexylammonium chloride, and tetraheptylammonium bromide, tetramethylammonium chloride); quaternary phosphonium salts, e.g., tetrabutylphosphonium salts, tetraphenylphosphonium chloride, benzyltriphenylphosphonium chloride, tributylallylphosphonium chloride, tributylbenzylphosphonium, tributyl - 2 - methoxypropylphosphonium chloride, benzyldiphenyl(dimethylamino)phosphonium chloride, 8 - benzyl - 1,8 - diazabicyclo[5.4.0]7 - undecanium chloride, benzyltris(dimethylamino)phosphonium, and bis(benzyldiphenylphosphine)iminium chloride. Other suitable organic onium compounds include 1,8 - diazabicyclo[5.4.0]undec - 7 - ene and 1,5 - diazabicyclo[4.3.0]nona - 5 - ene. Phenolate is a preferred anion for quaternary ammonium salts and phosphonium salts.

[0049] In one embodiment, the organic onium compound is used in an amount of at least 1, 1.5, 2, or even 2.5 millimoles to a maximum of 3.5, 4, 4.5, or even 5 millimoles per 100 parts by weight (grams) of the amorphous fluoropolymer.

[0050] There are also other known crosslinking systems. For example, a triazine crosslinking system for forming a triazine ring using an organotin compound by using a fluorine-containing elastomer having a nitrile group introduced as a crosslinking point (for example, JP58-152041A), similarly, an oxazole crosslinking system for forming an oxazole ring using bisaminophenol by using a fluorine-containing elastomer having a nitrile group introduced as a crosslinking point (for example, JP59-109546A), an imidazole crosslinking system for forming an imidazole ring using a tetraamine compound (for example, JP59-109546A), and a thiazole crosslinking system for forming a thiazole ring using bisaminothiophenol (for example, JP8-104789A). A method of crosslinking with radiation or an electron beam can also be used.

[0051] Particularly preferred crosslinking agents are compounds having a plurality of 3-amino-4-hydroxyphenyl groups, 3-amino-4-mercaptophenyl groups, or 3,4-diaminophenyl groups. Examples of these are, for example, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (commonly called bis(aminophenol) AF), 2,2-bis-(3-amino-4-mercaptophenyl)hexafluoropropane, tetraaminobenzene, bis-3,4-diaminophenylmethane, bis-3,4-diaminophenylether, 2,2-bis(3,4-diaminophenyl)hexafluoropropane, and the like.

[0052] For example, any additives including stabilizers (for example, antioxidants or ultraviolet and light stabilizers), antibacterial agents, pigments (for example, dyes), flame retardants, drugs, foaming agents, fillers, process aids, pigments, fillers, pore-forming agents, etc. may be added to the curable fluoropolymer composition. The use of such additives is for improving physical properties such as tensile strength, density, and elastic modulus.

[0053] Examples of such fillers include organic fillers or inorganic fillers [such as clay, silica (SiO2), alumina, red iron oxide, talc, diatomaceous earth, barium sulfate, wollastonite (CaSiO3), calcium carbonate (CaCO3), titanium oxide, iron oxide, and carbon black fillers, etc.], and polytetrafluoroethylene powder, PFA (TFE / perfluorovinyl ether copolymer) powder, conductive fillers, heat dissipating fillers, etc. may be added to the composition as optional components. Those skilled in the art can select a specific filler in an amount necessary to obtain the desired physical properties in the cured product.

[0054] In one embodiment, the curable composition contains less than 40, 30, 20, 15, 10, 5, 1, or even less than 0.1% by weight of filler and / or any additives.

[0055] Also, in order to enhance the properties of the resulting cured product, conventional auxiliaries may be incorporated into the curable composition of the present disclosure. For example, an acid acceptor may be used to promote the curing and thermal stability of the compound. Suitable acid acceptors include magnesium oxide, lead oxide, calcium oxide, calcium hydroxide, dibasic lead phosphite, zinc oxide, barium carbonate, strontium hydroxide, calcium carbonate, hydrotalcite, alkali stearate, magnesium oxalate, or combinations thereof. The acid acceptor is preferably used in an amount in the range of at least 1, 2, 4, or even 5% by weight, and up to 10, 15, or even 20% by weight, per weight of the fluoropolymer.

[0056] In one embodiment, the curable composition contains a strong organic base having at least 10, or even at least 12 pKa values, such as 1,8-bis-(dimethylamino)naphthalene, as disclosed in U.S. Patent No. 4,983,680 (Ojakaar), which is incorporated herein by reference. In one embodiment, the strong organic base is used in an amount of at least 0.1, 0.2, or even 0.4% by weight to a maximum of 0.6, 0.8, 1.0, 1.5, or even 2% by weight, based on the weight of the amorphous fluoropolymer.

[0057] In one embodiment, the curable composition (and the resulting cured article) substantially does not contain an acid acceptor, which means that the curable composition (or the resulting cured article) contains less than 0.5%, 0.1%, 0.05%, 0.01% by weight of the acid acceptor based on the weight of the fluoropolymer, or even further does not contain an acid acceptor.

[0058] A curable composition containing an amorphous fluoropolymer and a plurality of metal fluoride particles can be prepared by mixing the above components using a typical rubber processing machine such as an open roll, a Banbury mixer, or a kneader. The composition can also be prepared by a method using an internal mixer and a method of co-coagulating from an emulsion mixture and then compounding the mixture with a curing agent and / or an additive.

[0059] This process of mixing these components to produce such a solid polymer composition containing other components is typically referred to as "compounding". Such devices include mills for rubber, closed mixers such as Banbury mixers, and mixing extruders. The temperature of the mixture during mixing typically does not rise above about 120°C. During mixing, the constituents and additives are uniformly distributed throughout the resulting fluoropolymer "compound" or polymer sheet. Thereafter, the "compound" can be extruded or pressed in a mold, such as a cavity or a transfer mold, and subsequently oven-cured. In an alternative embodiment, curing may be performed in an autoclave.

[0060] Pressurization (i.e., press curing) of the compounded mixture is typically carried out at a temperature of about 120°C to 220°C, preferably about 140°C to 200°C, for about 1 minute to about 15 hours, usually about 1 to 15 minutes. A pressure of about 700 kPa to 20,000 kPa, preferably about 3400 kPa to 6800 kPa, is typically used in the molding of the composition. The molding die may be first coated with a release agent and pre-baked.

[0061] The formed vulcanized product may be post-cured in an oven at a temperature of about 140 to 240 °C, preferably about 160 to 230 °C, for about 1 to 24 hours or more, depending on the cross-sectional thickness of the sample. In the thick portion, the temperature during post-curing usually gradually rises from the lower limit of the range to the desired maximum temperature. The maximum use temperature is preferably about 260 °C and is held at this value for about 1 hour or more.

[0062] In one embodiment, the metal fluoride particles in the cured article are used in an amount of at least 5, 10, 15, 20, or even 25 pphr (parts by weight per 100 parts by weight of rubber), and at most 60, 50, 40, or even 30 pphr.

[0063] In one embodiment, the molded article is treated by a special cleaning method known in the art. For example, such cleaning methods include washing with ultrapure water, washing with a clean organic compound in liquid form at a specific temperature, washing with a clean aqueous inorganic solution, dry etching cleaning, or extraction cleaning. Such cleaning methods can be used to reduce the number of fine particles and / or the metal content.

[0064] The cured fluoropolymer articles disclosed herein are particularly suitable for various parts of semiconductor manufacturing equipment. In the present invention, the semiconductor manufacturing equipment is not particularly limited to equipment for manufacturing semiconductors, and includes all manufacturing equipment used in the field of semiconductors that require a high degree of cleanliness, such as equipment for manufacturing liquid crystal panels and plasma panels.

[0065] In particular, fluorine-containing elastomer molded articles can be suitably used for the production of sealing materials for sealing semiconductor manufacturing equipment that requires a high degree of cleanliness. Examples of sealing materials include O-rings, square rings, quick-connect seals, gaskets, packings, oil seals, bearing seals, lip seals, and the like.

[0066] This is because there are stringent requirements associated with the use of fluoroelastomers in the semiconductor industry. To predict whether a fluoroelastomer article is suitable for use, various test methods, including chemical stability, have been developed.

[0067] One such test method is related to weight loss, where the fluoroelastomer article is exposed to plasma and the weight loss is determined. In one embodiment, the fluoroelastomer exhibits a weight loss rate after exposure to oxygen plasma of less than 3.0, 2.0, or even 1.0. In one embodiment, the fluoroelastomer exhibits a weight loss rate after exposure to carbon tetrafluoride and oxygen plasma of less than 3.0, 2.0, or even 1.0.

[0068] In one embodiment, there is no discoloration of the fluoroelastomer after plasma treatment, which means that there is no obvious change between the fluoroelastomer before and after treatment when visually inspected with the naked eye after plasma treatment.

[0069] In one embodiment, the fluoroelastomer exhibits a swelling of less than 3, 2, 1, or even 0.5% when exposed to water at 80°C for 168 hours. In one embodiment, the fluoroelastomer exhibits a swelling of less than 3, 2, or even 1.5% when exposed to water at 200°C for 168 hours.

Examples

[0070] Various modifications and variations of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. It is not intended that the present invention be unduly limited by the exemplary embodiments and examples described herein, and such examples and embodiments are presented only by way of example, and it is to be understood that the scope of the present invention is intended to be limited only by the claims set forth below in this specification.

[0071] All materials are commercially available from, for example, Sigma-Aldrich Chemical Company (Milwaukee, WI, USA) or are known to those skilled in the art, unless otherwise specified or apparent.

[0072] In this section, the following abbreviations are used: mL = milliliter, g = gram, in = inch, cm = centimeter, μm = micrometer, nm = nanometer, min = minute, h = hour, r.t. = room temperature, °C = degree Celsius, phr = parts by weight per 100 parts by weight of rubber, sccm = standard cubic centimeter per minute, mTorr = millitorr. The abbreviations of the materials used in this section, as well as the descriptions of the materials, are shown in Table 1.

Table 1

[0073] Average particle size:

[0074] The average particle size marked with " * " in Table 1 was obtained by dispersing the obtained particles in an aqueous solution of 0.2% sodium hexametaphosphate. The particle size was measured using a laser scattering particle size distribution analyzer (partica LA-950V2 available from Horiba Ltd., Kyoto, Japan). The average particle size not marked was obtained from the supplier.

[0075] Compounding

[0076] Powder blends (CE-2 to CE-5 and EX-1 to EX-3)

[0077] Perfluoroelastomer (FFKM), filler (fluoride or oxide), 2 phr of TAIC and 1.25 phr of DBPH were mixed on a 6-inch (15.24 cm) open roll mill.

[0078] Latex blend (CE-1 SiO2 latex)

[0079] The perfluoroelastomer latex (FFKM latex) and SiO2 latex were mixed in a plastic cup, and the mixture was left at -40°C for 16 hours. The cold mixture was left at room temperature for 4 hours. Then, the solids were filtered from the water with cheesecloth, gently squeezed, and returned to deionized water. The mixture was then stirred to rinse the material, and the filtration and rinsing procedures for the solids were repeated. The finally recovered solids were placed in a batch oven at 130°C for 16 hours.

[0080] The dried material, 2 phr of TAIC and 1.25 phr of DBPH were mixed on a 6-inch (15.24 cm) open roll mill.

[0081] Molded O-ring

[0082] They were molded into O-rings at 177°C for 12 minutes (AS568 standard, AS568 - 214). Then, they were post-cured at 200°C for 16 hours. The press-cured and post-cured O-rings were tested for plasma resistance and water swelling as described below. The results are shown in Tables 3 and 4 below.

[0083] Plasma resistance

[0084] Samples were tested in a Mini-Lab Plasma Pod available from JLS Designs Ltd, Somerset, UK, by exposing them to two different plasma conditions: (1) O2 plasma: 30 sccm, 100 W, 225 mTorr, (2) CF4 / O2 plasma: 3 sccm (CF4), 27 sccm (O2), 100 W, 225 mTorr. A quarter-size of the O-ring was weighed on a scale. They were placed on the pod of the plasma tester. They were exposed to the plasma gas for 3 hours. Then, they were weighed again on a scale, and the weight loss percentage was calculated according to the following formula.

Equation

[0085] The results shown in Table 2 represent the average of three runs for each sample.

Table 2

[0086] Water swelling

[0087] The samples were placed in a wide-mouth glass bottle for the 80 °C test or in a pressure-resistant stainless steel tube for the 200 °C test. The 1 / 2 size of the D-214O ring was weighed on a scale. They were placed in a wide-mouth glass bottle for the 80 °C test or in a pressure-resistant stainless steel tube for the 200 °C test. The cap was closed and they were placed in an oven at 80 °C or 200 °C for 168 hours as shown in Table 3. They were taken out and weighed again on a scale, and the swelling percentage was calculated by the following formula.

Equation

[0088] Next, the samples were dried in an oven at 120 °C for 16 hours. They were taken out and weighed again on a scale, and the percentage change was calculated by the following formula.

Equation

Table 3

[0089] It will be apparent to those skilled in the art that predictable modifications and changes of the present invention that do not depart from the scope and spirit of the present invention. The present invention is not limited to the embodiments described in this application for illustrative purposes. The present invention includes the following aspects. (1) A curable fluoropolymer composition comprising an amorphous fluoropolymer, particles of a metal fluoride, wherein the particles are substantially untreated, and the metal of the metal fluoride comprises at least one of an alkaline earth metal, a Group III transition metal, and a lanthanide metal, particles of a metal fluoride, A curable fluoropolymer composition comprising. (2) The curable fluoropolymer composition according to item 1, wherein the metal fluoride has a solubility in water of less than 0.5 g / 100 g at 20 °C and ambient pressure. (3) The curable fluoropolymer composition according to item 1 or 2, wherein the metal of the metal fluoride comprises at least one of the group consisting of Ca, Mg, Y, and Yb. (4) The curable fluoropolymer composition according to any one of items 1 to 3, wherein the particles of the metal fluoride have an average diameter of less than 1 mm. (5) The curable fluoropolymer composition according to any one of items 1 to 4, wherein the particles of the metal fluoride have an average diameter of less than 500 nm. (6) The curable fluoropolymer composition according to any one of items 1 to 5, comprising at least 0.1% by weight and at most 30% by weight of the particles of the metal fluoride. (7) The curable fluoropolymer composition according to any one of items 1 to 6, wherein the amorphous fluoropolymer is derived from at least one monomer selected from tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, propylene, perfluoropropyl vinyl ether, CF 2 =CF-O-CF 2 -O-CF 3 , CF 2 =CF-O-CF 2 -O-CF 2 CF 3 , CH 2 =CF-CF 3 , perfluoromethyl vinyl ether, 3-methoxyperfluoropropyl vinyl ether, CF 2 CF-O-CF 2 -O-CF 2 CF 2 CF 3 , and CF 2 CF-O-CF 2 -O-CF 2 CF 2 CF 2 -O-C 3 F 7 . (8) The curable fluoropolymer composition according to any one of items 1 to 7, wherein the amorphous fluoropolymer is perfluorinated. (9) The curable fluoropolymer composition according to item 8, wherein the amorphous fluoropolymer is derived from at least one of a perfluorinated olefin and a perfluorinated vinyl ether. (10) The curable fluoropolymer composition according to any one of items 1 to 9, wherein the amorphous fluoropolymer comprises at least one of an iodine and a bromine-containing curing site group. (11) The curable fluoropolymer composition according to any one of items 1 to 10, wherein the amorphous fluoropolymer contains a nitrogen-containing curing site group. (12) The curable fluoropolymer composition according to item 11, wherein the nitrogen-containing curing site is selected from at least one of nitrile, imidate, amidoxime, and amidrazone. (13) The curable fluoropolymer composition according to any one of items 1 to 12, further comprising a curing agent. (14) The curable fluoropolymer composition according to item 13, wherein the curing agent is at least one of peroxide, bisaminophenol, triazine-forming curing agent, and onium. (15) A method for manufacturing an article, comprising: providing the curable fluoropolymer composition according to any one of items 1 to 14, and then curing the composition. (16) A cured article, comprising: a fluoroelastomer; and particles of a metal fluoride, wherein the particles are substantially untreated on the surface, and the metal of the metal fluoride contains at least one of an alkaline earth metal, a Group III transition metal particle, and a lanthanide. (17) The cured article according to item 16, wherein the fluoroelastomer is perfluorinated. (18) The cured article according to item 16 or 17, wherein the metal fluoride has a solubility in water of less than 0.5 g / 100 g at 20 °C and ambient pressure. (19) The cured article according to any one of items 16 to 18, wherein the metal of the metal fluoride contains at least one of the group consisting of Ca, Mg, Y, and Yb. (20) The cured article according to any one of items 16 to 19, wherein the particles of the metal fluoride have an average diameter of less than 1 mm. (21) The cured article according to any one of items 16 to 19, wherein the particles of the metal fluoride have an average diameter of less than 500 nm. (22) The cured article according to any one of items 16 to 21, wherein the cured article contains at least 0.1% by weight and at most 30% by weight of the particles of the metal fluoride.

Claims

1. A curable fluoropolymer composition comprising: An amorphous fluoropolymer containing at least one of an iodine-containing curing site group, a bromine-containing curing site group, and a nitrogen-containing curing site group; Particles of a metal fluoride, wherein the amount of the organic portion on the surface of the particles is less than 10% by weight compared to the weight of the metal fluoride particles, and the metal of the metal fluoride contains at least one of an alkaline earth metal, a Group III transition metal, and a lanthanide metal; A curable fluoropolymer composition.

2. The curable fluoropolymer composition according to claim 1, wherein the metal fluoride has a solubility in water of less than 0.5 g / 100 g at 20 °C and ambient pressure.

3. The curable fluoropolymer composition according to claim 1 or 2, wherein the metal of the metal fluoride contains at least one of the group consisting of Ca, Mg, Y, and Yb.

4. The curable fluoropolymer composition according to any one of claims 1 to 3, wherein the metal fluoride particles have an average diameter of less than 1 mm.

5. The curable fluoropolymer composition according to any one of claims 1 to 4, containing at least 0.1% by weight and at most 30% by weight of the metal fluoride particles.

6. The curable fluoropolymer composition according to any one of claims 1 to 5, further comprising a curing agent containing a peroxide, bisaminophenol, adipate, amidine, acetate, a triazine-forming curing agent, or a combination thereof.

7. A method for manufacturing an article, comprising: Providing a curable fluoropolymer composition according to any one of claims 1 to 6, and then curing the composition.

8. A cured article comprising: A fluoroelastomer containing at least one of an iodine-containing curing site group, a bromine-containing curing site group, and a nitrogen-containing curing site group; Particles of a metal fluoride, wherein the amount of the organic portion on the surface of the particles is less than 10% by weight compared to the weight of the metal fluoride particles, and the metal of the metal fluoride contains at least one of an alkaline earth metal, a Group III transition metal particle, and a lanthanide.

9. The cured article according to claim 8, wherein the metal fluoride has a solubility in water of less than 0.5 g / 100 g at 20° C. and ambient pressure.

10. The cured article according to claim 8 or 9, wherein the metal of the metal fluoride comprises at least one of the group consisting of Ca, Mg, Y, and Yb.

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