Dry powder blend of an amorphous perfluorinated polymer, method for producing the same, and article derived from the dry powder blend

Abstract

A method for producing a curable perfluoroelastomer is described herein, wherein the curable perfluoroelastomer comprises particles of a semi-crystalline fluoropolymer, and the semi-crystalline fluoropolymer is a TFE copolymer comprising 1 wt% or less of at least one additional fluorinated monomer. The method includes: (a) obtaining particles of an amorphous perfluoropolymer and a semi-crystalline fluoropolymer; and (c) dry-blending the amorphous perfluoropolymer with the particles to form a curable perfluoroelastomer.

Description

Technical Field

[0001] There is disclosed a dry powder blend comprising amorphous perfluoropolymers and semi-crystalline fluoropolymer particles. Using such blends, filled perfluoroelastomers can be produced, which can have improved plasma resistance and / or temperature stability.

Summary of the Invention

[0002] It is desirable to identify filled perfluorinated elastomer compositions having improved properties such as flexibility, heat resistance, and / or plasma resistance.

[0003] In one aspect, a dry powder blend is disclosed. The dry powder blend includes (i) an amorphous perfluoropolymer containing a curing site selected from the group consisting of -CN, -I, and -Br, and (ii) a plurality of semi-crystalline fluoropolymer particles, wherein the semi-crystalline fluoropolymer particles include a tetrafluoroethylene copolymer containing at least one additional fluorinated monomer of 1 wt% or less, and the semi-crystalline fluoropolymer particles have (i) a melt flow index (MFI, at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) are not melt processable and have a standard specific gravity (SSG) of less than 2.200.

[0004] In another aspect, there is disclosed a curable perfluoropolymer composition comprising a homogeneous blend of amorphous perfluoropolymer particles and semi-crystalline fluoropolymer particles, wherein the semi-crystalline fluoropolymer particles include a tetrafluoroethylene (TFE) copolymer containing at least one additional fluorinated monomer of 1 wt% or less, and the semi-crystalline fluoropolymer particles have (a) an MFI (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (b) are not melt processable and have an SSG of less than 2.200.

[0005] In another aspect, a cured perfluoroelastomer comprising a perfluoropolymer filled with semi-crystalline fluoropolymer particles, wherein the semi-crystalline fluoropolymer particles comprise a tetrafluoroethylene (TFE) copolymer comprising at most 1 wt% of at least one additional fluorinated monomer, and wherein the semi-crystalline fluoropolymer particles have (a) an MFI (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (b) are not melt processable and have an SSG of less than 2,200, is disclosed.

[0006] In yet another aspect, a method of manufacturing a curable perfluoroelastomer, comprising: (a) obtaining (i) an amorphous perfluoropolymer and (ii) particles of a semi-crystalline fluoropolymer of a TFE copolymer comprising at most 1 wt% of at least one additional perfluorinated monomer; (b) contacting the amorphous perfluoropolymer with the semi-crystalline particles; (c) dry blending the amorphous perfluoropolymer and the particles to form a curable perfluoroelastomer.

[0007] The above summary of the present disclosure is not intended to describe each embodiment. Details of one or more embodiments of the invention are also set forth in the following description. Other features, objects, and advantages will be apparent from the description and claims. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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 a chemical bond or chemical group. "Hardened portion" refers to a functional group that may be involved in crosslinking. "Copolymerization" refers to the polymerization of monomers together to form the polymer main chain. "Monomer" is a molecule that can form part of the basic structure of a polymer after polymerization, and "Polymer" refers to a macrostructure containing repeating copolymerized monomer units.

[0009] Furthermore, in this specification, the description of a range by endpoints includes all numbers included within that range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0010] Furthermore, in this specification, the description of "at least one" includes all numbers of 1 or more (for example, 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.).

[0011] As used in this specification, "including at least one of A, B, and C" refers to the single element A, the single element B, the single element C, A and B, A and C, B and C, and all combinations of the three.

[0012] This application relates to an amorphous perfluorinated polymer used in the manufacture of perfluorinated elastomers. Perfluorinated elastomers are used in a wide range of applications that encounter harsh environments, particularly end-use applications that are exposed to high temperatures and reactive chemicals. In the semiconductor industry, perfluorinated elastomers are used in processes that require resistance to NF3 plasma. However, in this industry, there are strict requirements, particularly regarding the purity of materials related to metal ions.

[0013] A base polymer with improved properties (such as thermal stability, plasma resistance, etc.) can be provided by using a high fluorine-containing polymer as a filler. Both PTFE and PFA polymers are high fluorine-containing polymers. Conventionally, PFA (perfluoroalkoxy copolymer) polymers, which are thermoplastic resins that can be melt processed and are easy to process, have been used as fillers in perfluoroelastomer compositions for semiconductor applications.

[0014] The incorporation of PTFE (TFE homopolymer) would be ideal to add to amorphous perfluoropolymers because it has excellent thermal and chemical stability. However, as shown in the Examples section, PTFE fibrillates and tends to result in a rough appearance in the final product due to, for example, the difficulty of grinding and the non-uniform incorporation of PTFE.

[0015] Modified PTFE is a TFE polymer containing such a low concentration of comonomer that the polymer remains non-melt processable and typically contains at least one additional fluorinated monomer of 1 wt% or less. Thus, these materials can be dry blended into the base polymer. In at least some embodiments, under certain shear conditions, these materials can fibrillate and / or agglomerate detrimentally.

[0016] It has been discovered in the present disclosure that dry blending particles of a particular type of modified PTFE with an amorphous perfluoropolymer can result in a filled perfluoropolymer gum having improved properties.

[0017] Semicrystalline fluoropolymer particles

[0018] The particles of the present disclosure are semicrystalline fluoropolymers of modified PTFE.

[0019] Modified PTFE is a polymer of tetrafluoroethylene modified with a small amount, for example, 1, 0.5, 0.1, 0.05 wt% or less, or even 0.01 wt% or less of another fluorinated monomer. Exemplary fluorinated monomers include perfluorinated ethers of the following formula R f -O-(CF2) m CF=CF2 (wherein m is 0 or 1, and Rf represents a perfluoroalkyl residue containing at least one carbon atom, which may have at least one in-chain oxygen atom (i.e., an ether bond) intervening). Exemplary unsaturated fluorinated ether monomers include perfluoro(2-propoxypropyl vinyl) ether (PPVE-2), perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), perfluoro(3-methoxy-n-propyl vinyl) ether (MV-31), perfluoro(2-methoxy-ethyl vinyl) ether, perfluoro(n-propyl vinyl) ether (PPVE-1), perfluoro(methyl allyl) ether (MA-1), perfluoro(ethyl allyl) ether (MA-2), perfluoro(n-propyl allyl) ether (MA-3), perfluoro(n-butyl allyl) ether (MA-4), CF3-O-(CF2)3-O-CF2-CF=CF2 (MA31) and F3C-(CF2)2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-O-CF=CF2 (PPVE-3).

[0020] In one embodiment, the modified PTFE is modified with a perfluorinated vinyl ether or a perfluorinated allyl ether to achieve low deformation under load. In one embodiment, the modified PTFE is modified with a small amount of perfluorinated allyl ether monomer.

[0021] In one embodiment, the semi-crystalline fluoropolymer particles include groups that can interact (e.g., bond) with amorphous perfluoropolymer particles, such as nitrile, bromine, or iodine sites. Such groups may be introduced into the semi-crystalline fluoropolymer via a chain transfer agent or a curing site monomer used during polymerization.

[0022] In one embodiment, the semi-crystalline fluoropolymer particles are random copolymers produced by copolymerizing tetrafluoroethylene with different fluorinated monomers such as perfluorinated allyl ethers.

[0023] In another embodiment, the semi-crystalline fluoropolymer particles are core-shell particles that include a core of one composition (TFE homopolymer or TFE copolymer) and a shell of a different composition (e.g., a shell derived from different monomers or a shell with a different concentration of monomers than the core). In the case of core-shell particles, typically the core has an average diameter of 10, 25 nm, or even 40 nm or more and up to 100, 125 nm, or even 150 nm at the longest. The shell can be thick or thin. For example, in one embodiment, the outer shell is a TFE copolymer having a thickness of 100 nm, or even 125 nm or more and up to 200 nm at the longest. In another embodiment, the outer shell is a TFE copolymer having a thickness of 1, 2 nm, or even 5 nm or more and up to 15 nm, or even 20 nm at the longest. Exemplary modified PTFE core-shell particles have a shell derived from perfluorinated vinyl ether, perfluorinated allyl ether, and / or a curing site-containing monomer. The total content of the modifier (e.g., perfluorinated vinyl ether, perfluorinated allyl ether, and curing site-containing monomer) is less than 1, less than 0.5 wt%, or even less than 0.2 wt% on average of the weight of the particles. In one embodiment, the content of the second monomer in the semi-crystalline fluoropolymer particles is about 1000 parts per million.

[0024] The above semi-crystalline fluoropolymer particles can be produced by using techniques known in the art, for example, by aqueous emulsion polymerization with or without a fluorinated emulsifier, followed by coagulation, aggregation, and drying of the latex to recover the semi-crystalline fluoropolymer particles.

[0025] In one embodiment, the semi-crystalline fluoropolymer fibrillates upon shearing.

[0026] The semi-crystalline fluoropolymer particles may or may not be melt processable.

[0027] Melt processable semi-crystalline fluoropolymer particles are materials having a low molecular weight. Such low molecular weight polymers have an MFI (melt flow index) at 372 °C and a load of 2.16 kg of less than 50, 45, or even 40 g / 10 min. Materials having an MFI at 372 °C and 21.6 kg of less than 5 g / 10 min, less than 1 g / 10 min, or less than 0.5 g / 10 min are also considered to be melt processable.

[0028] In one embodiment, the semi-crystalline fluoropolymer has a melting point after a second heating above 320, or even 330 °C. As solids, modified PTFE and PTFE can exist in different phases that can be measured by thermomechanical analysis. For example, as described in Sperati, C.A., Adv. Polym. Sci., 2:465, 1961, at about 19 °C and atmospheric pressure, PTFE changes from triclinic crystal II to hexagonal crystal IV, and at about 32 °C and atmospheric pressure, from hexagonal crystal IV to pseudo-hexagonal crystal I. Such physical changes occur at the phase transition temperature, which can be indicated by a peak when monitoring the heat flow versus temperature of the solid material using DMA (dynamic mechanical analysis). In one embodiment, the semi-crystalline fluoropolymer has a phase transition temperature above 15, 16, or even 17 °C and up to 20, 21, or even 22 °C.

[0029] Semicrystalline fluoropolymer particles having a higher molecular weight fluoropolymer are essentially impossible to melt process (having a melt flow index of less than 0.1, 0.05, or even 0.001 g / 10 min at 372 °C and 21.6 kg). The molecular weight of these non-melt-processable polymers cannot be measured by prior art. Therefore, an indirect method correlating with the molecular weight such as standard specific gravity (SSG) is used. The lower the SSG value, the higher the average molecular weight. The SSG of the PTFE of the present disclosure is at most 2.200, 2.190, 2.185, 2.180, 2.170, 2.160, 2.157, 2.150, 2.145, or even 2.130 g / cm 3 when measured according to ASTM D4895-04. Exemplary non-melt-processable semi-crystalline fluoropolymer particles include core-shell particles derived from a perfluorinated vinyl or allyl ether as a modifier in the shell and / or core, and random copolymer particles derived from a nitrile-containing cured site monomer.

[0030] Amorphous perfluoropolymer

[0031] An amorphous perfluoropolymer is a macromolecule containing copolymerized repeating divalent monomer units, each of the monomer units being fully fluorinated (in other words, the monomer unit contains at least one C-F bond and no C-H bond). The fully fluorinated polymer may contain non-fully fluorinated end groups based on initiators and / or chain transfer agents, which are used as known in the art.

[0032] Fully fluorinated polymers are generally obtained by polymerizing one or more fully fluorinated monomers such as fully fluorinated olefins and fully fluorinated olefins containing an ether bond. Exemplary fully fluorinated monomers include perfluoroether monomers such as tetrafluoroethylene, hexafluoropropylene, pentafluoropropylene, trifluorochloroethylene, perfluoro-vinyl ether monomer and perfluoroallyl ether monomer.

[0033] Examples of perfluoroethers that can be used in the present disclosure include those corresponding to the formula CF2=CF(CF2) m -O-R f (wherein m is 0 or 1, and R f represents a perfluorinated aliphatic group that may contain 0, or one or more oxygen atoms, and 12 or fewer, 10 or fewer, 8 or fewer, 6 or fewer, or even 4 or fewer carbon atoms).

[0034] Examples of perfluorinated vinyl ether monomers are those corresponding to the formula CF2=CFO(R a f O) n (R b f O) m R c f [wherein R a f and R b f are different linear or branched perfluoroalkylene groups having 1 to 6 carbon atoms, particularly 2 to 6 carbon atoms, m and n are independently 0 to 10, and R c f is a perfluoroalkyl group having 1 to 6 carbon atoms]. Specific examples of perfluorinated vinyl 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] etc. are included.

[0035] Examples of perfluoroallyl ether monomers that can be used in the present disclosure include those corresponding to the formula CF2=CF(CF2)-O-R f [wherein R frepresents a perfluorinated aliphatic group that may contain 0, or one or more oxygen atoms, and 10 or fewer, 8 or fewer, 6 or fewer, or even 4 or fewer carbon atoms. Examples corresponding thereto include n F [wherein n is an integer from 1 to 5], and CF2=CF-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]. Examples of perfluorinated allyl ethers include perfluoro(methyl allyl) ether (CF2=CF-CF2-O-CF3), perfluoro(ethyl allyl) ether, perfluoro(n-propyl allyl) ether, perfluoro-2-propoxypropyl allyl ether, perfluoro-3-methoxy-n-propyl allyl ether, perfluoro-2-methoxy-ethyl allyl ether, perfluoro-methoxy-methyl allyl ether, and

Chemical formula

[0036] In the present disclosure, the perfluorinated polymer may be polymerized in the presence of a chain transfer agent and / or a curing site monomer to introduce a curing site such as I, Br, and / or CN into the fluoropolymer.

[0037] Exemplary chain transfer agents include iodine chain transfer agents, bromine chain transfer agents, or chlorine chain transfer agents. For example, a preferred iodine chain transfer agent for polymerization is of the formula RI x [wherein (i) R is a perfluoroalkyl group or a chloroperfluoroalkyl group having 3 to 12 carbon atoms, and (ii) x = 1 or 2]. The iodine chain transfer agent is I(CF2) n -O-(CF2) m-I [wherein n and M are integers independently selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or even 12] and may be a perfluorinated iodine compound. Exemplary iodine-perfluoro compounds include 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,10-diiodoperfluorodecane, 1,12-diiodoperfluorododecane, 2-iodo-1,2-dichloro-1,1,2-trifluoroethane, 4-iodo-1,2,4-trichloroperfluorobutane, and mixtures thereof. In some embodiments, bromine is of the formula RBr x [wherein (i) R is a perfluoroalkyl group or chloroperfluoroalkyl group having 3 to 12 carbon atoms, and (ii) x is 1 or 2] and is derived from a brominated chain transfer agent. The chain transfer agent may be a perfluorobromo compound.

[0038] In one embodiment, the curing site is of the following formula, namely, a) CX2=CX(Z) [wherein (i) each X is independently H or F, and (ii) Z is I, Br, R f -U (wherein U is I or Br, and R f is a perfluorinated alkylene group optionally containing an O atom.) or (b) Y(CF2) q Y [wherein (i) Y is Br or I or Cl, and (ii) q is from 1 to 6.] and may be derived from one or more of the monomers. In addition, non-fluorinated bromo or iodo olefins, such as vinyl iodide and allyl iodide, can be used. In some embodiments, the curing site monomer is derived from one or more compounds selected from the group consisting of CF2=CFCF2I, ICF2CF2CF2CF2I, CF2=CFCF2CF2I, CF2=CFOCF2CF2I, CF2=CFOCF2CF2CF2I, CF2=CFOCF2CF2CH2I, CF2=CFCF2OCH2CH2I, CF2=CFO(CF2)3-OCF2CF2I, CF2=CFCF2Br, CF2=CFOCF2CF2Br, CF2=CFCl, CF2=CFCF2Cl, and combinations thereof.

[0039] In another embodiment, the curing site monomer includes a nitrogen-containing curing moiety. Useful nitrogen-containing curing site monomers include nitrile-containing fluorinated olefins and nitrile-containing fluorinated vinyl ethers [perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene), CF2=CFO(CF2) L CN (wherein L is an integer from 2 to 12), CF2=CFO(CF2) u OCF(CF3)CN (wherein u is an integer from 2 to 6), CF2=CFO[CF2CF(CF3)O] q (CF2O) y CF(CF3)CN or CF2=CFO[CF2CF(CF3)O] q (CF2) y OCF(CF3)CN (wherein q is an integer from 0 to 4 and y is an integer from 0 to 6), or CF2=CF[OCF2CF(CF3)] r O(CF2) t CN (wherein r is 1 or 2 and t is an integer from 1 to 4), and derivatives and combinations of the above-mentioned ones, etc.] may be mentioned. Examples of nitrile-containing curing site monomers include CF2=CFO(CF2)5CN, CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF(CF3)CN, CF2=CFOCF2CF2CF2OCF(CF3)CN, CF2=CFOCF2CF(CF3)OCF2CF2CN, and combinations thereof.

[0040] In one embodiment, the amorphous perfluoropolymer has a glass transition temperature of less than 20, 10, 5, 0, -5, -10 °C, or even less than -15 °C.

[0041] Blend

[0042] In the present disclosure, particles of semi-crystalline fluoropolymers (i.e., modified PTFE) and amorphous perfluoropolymers are combined using standard mixing equipment for dry blend components. Exemplary mixing techniques include, for example, kneading using a two-roll mill for rubber, a pressure kneader, or a Banbury mixer. As used herein, dry blending means blending components that contain little to no water or solvent, as opposed to latex, liquid dispersions, or solution blends where significant amounts of water or solvent are present. Optionally, the dry blending process may be carried out in two steps in which the amorphous perfluoropolymer and the particles are pre-blended prior to the introduction of a curative. In one embodiment, the average primary particle size of the particles is 50, 75, 100 nm, or even 125 nm or more and up to 200, 250, 300, 400 nm, or even 500 nm. These primary particles may aggregate with each other to form aggregates having an average diameter of 5, 10, 25, 50, 75, 100, or even 125 micrometers or more and up to 500, 600, 800, or even 1000 micrometers.

[0043] In one embodiment, the curable fluoropolymer blend comprises 5, 10, or even 15 weight % or more and up to 20, 25, 30, or even 35 weight % of a semi-crystalline fluoropolymer. Optionally, additional fillers and / or curing catalysts may be added to the blend.

[0044] In one embodiment, the blend has a melt temperature that exceeds 310, 312, 315, 318 °C, or even exceeds 320 °C. In one embodiment, the blend has a melt temperature that is less than 329, 327, 325 °C, or even less than 323 °C.

[0045] In one embodiment, the polymer blend has a decomposition temperature that exceeds 500, 501, 502, 503, 504 °C, or even exceeds 505 °C. In one embodiment, the blend has a decomposition temperature that is less than 510, 509, 508, 507 °C, or even less than 506 °C.

[0046] In one embodiment, the polymer blend has at least one recrystallization temperature below 310, 309, 308, 307 °C, or even below 305 °C.

[0047] A curing agent may be blended with or subsequently added to the amorphous perfluoropolymer containing the particles to cure the amorphous perfluoropolymer to produce a perfluoroelastomer.

[0048] Generally, the curable composition may contain two or more curing agents. The effective amount of the curing agent in the curable composition is 0.1, 0.5 wt%, or even 1 wt% or more and lower than 10, 8, 6 wt%, or even lower than 5 wt%, although larger and smaller amounts of the curing agent may also be used.

[0049] The curing agent can include curatives and curing catalysts. Examples of the curing agent include those known in the art including, inter alia, peroxides, triazine-forming curing agents, benzimidazole-forming curing agents, benzoxazole-forming curing agents, adipates, and acetates. These curing agents may be used by themselves or in combination with another curing agent.

[0050] The peroxide may also be used as a curing agent. Useful peroxides are those that generate free radicals at the curing temperature. Dialkyl peroxides or bis(dialkyl peroxides) that decompose at temperatures higher than 50 °C are particularly preferred. In many cases, it is preferred to use di-tert-butyl peroxide having a tertiary carbon atom bonded to peroxy oxygen. Examples of the peroxide to be selected 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, lauryl peroxide, and cyclohexanone peroxide. Other suitable peroxide curing agents are listed in U.S. Patent No. 5,225,504 (Tatsu et al.). The amount of the peroxide curing agent used is generally from 0.1 to 5 parts by weight, preferably from 1 to 3 parts by weight, per 100 parts of the amorphous perfluoropolymer.

[0051] In one embodiment, the curing agent may be selected from triazine-forming cured network structures. Such curing agents include organotin compounds (e.g., propargyl-, triphenyl- and arylenyl-, tetraalkyl-, and tetraaryl tin curing agents, etc.), ammonia-generating compounds (see, e.g., U.S. Patent No. 6,281,296), ammonium salts, such as ammonium perfluorooctanoate (see, e.g., U.S. Patent No. 5,565,512), and amidines (see, e.g., U.S. Patent No. 6,846,880), imidates (see, e.g., U.S. Patent No. 6,657,013), metallamine complexes (see, e.g., U.S. Patent No. 6,657,012), and hydrochlorides (see, e.g., U.S. Patent No. 6,794,457).

[0052] In another embodiment, the fluoropolymer blend can be cured using one or more peroxide curing agents together with an ammonia-generating catalyst. The curing catalyst may include, for example, a first component and a second component. The first component is represented by R’C(CF2R)O - Q + where Q + is a non-interfering organic phosphonium, organosulfonium, or organoammonium cation, each R independently represents H, a halogen, a hydrocarbyl group, or a halogenated hydrocarbyl group, at least one carbon atom of the hydrocarbyl group may be further substituted with one or more heteroatoms selected from N, O, and S, R’ represents H, a hydrocarbyl group, or a halogenated hydrocarbyl group, at least one carbon atom of the hydrocarbyl group may be further substituted with one or more heteroatoms selected from N, O, and S, or any two of R or R’ may together form a divalent hydrocarbylene group, and at least one carbon atom of the hydrocarbylene group may be further substituted with one or more heteroatoms selected from N, O, and S. The second component is [N≡CCFR’’] bIndependently represented by Z, where each R'' independently represents F or CF3, b represents any positive integer, and Z represents a b-valent organic moiety free of interfering groups. See, for example, U.S. Patent No. 7,294,677. Examples include the reaction product of CF3OCF2CF2CN and tetrabutylphosphonium 2-(p-tolyl)-1,1,1,3,3,3-hexafluoroisopropoxide, the reaction product of CF3OCF2CF2CN and tetrabutylammonium 2-(p-tolyl)-1,1,1,3,3,3-hexafluoroisopropoxide, and combinations thereof.

[0053] Curing can be caused using a catalyst containing one or more ammonia-generating compounds. The ammonia-generating compounds include compounds that are solid or liquid under ambient conditions but generate ammonia under curing conditions. Such compounds include, for example, hexamethylenetetramine (urotropin), dicyandiamide, and the metal-containing compound of formula A w+ (NH3) v Y w- wherein A w+ is a metal cation such as Cu 2+ , Co 2+ , Co 3+ , Cu + , and Ni 2+ , w is equal to the valence of the metal cation, Y w- is a counterion, typically a halide, sulfate, nitrate, acetate, etc., and v is an integer from 1 to about 7.

[0054] Also useful as ammonia-generating compounds are substituted and unsubstituted triazine derivatives such as those of the following formula.

Chemical formula

[0055] In one embodiment, the curing agent is as follows: [Chemical formula] [wherein, A may be selected from SO2, O, CO, alkyl having 1 to 6 carbon atoms, perfluoroalkyl having 1 to 10 carbon atoms, or a carbon-carbon bond connecting two aromatic rings such as those disclosed in U.S. Patent No. 6,114,452]. For example, useful curing agents include bis(aminophenol) such as 2,2-bis[3-amino-4-hydroxyphenyl]hexafluoropropane, bis(aminothiophenol) such as 4,4'-sulfonylbis(2-aminophenol), and tetraamines such as 3,3'diaminobenzidine, and 3,3',4,4'-tetraaminobenzophenone.

[0056] Bisamidrazone compounds, for example, 2,2-bis(4-carboxyphenyl)hexafluoropropane bisamidrazone, and bisamidrazone and bisamidooxime may also be used as the curing agent.

[0057] In another embodiment, a curing agent (or a precursor thereof) of the following formula may be used: {R(A) n} (-n) {QR’ k (+)} n wherein R may be non-fluorinated, partially fluorinated, or fully fluorinated, C1-C 20 alkyl or alkenyl, C3-C 20 cycloalkyl or cycloalkenyl, or C6-C 20 aryl or aralkyl, or hydrogen. R may contain at least one heteroatom, i.e., a non-carbon atom such as O, P, S, or N. R may also be substituted such that one or more hydrogen atoms in the group are replaced by Cl, Br, or I. {R(A) n} (-n)is an acid anion or acid derivative anion, and n is the number of A groups in the anion. A is an acid anion or acid derivative anion. For example, A is a COO anion, SO3 anion, SO2 anion, SO2NH anion, PO3 anion, CH2OPO3 anion, (CH2O)2PO2 anion, C6H4O anion, OSO3 anion, O anion (when R is hydrogen, aryl, or alkylaryl),

Chem.

Chem.

Chem.

[0058] Other curing agents include bis-aminophenol (see, for example, U.S. Patent Nos. 5,767,204 and 5,700,879), organometallic compounds (see, for example, U.S. Patent No. 4,281,092), bis-amide oxime (see, for example, U.S. Patent No. 5,621,145), aromatic amino compounds, bisamide azone, bisamide oxime, and tetraphenyltin.

[0059] Depending on the curing site component present, it is also possible to use a dual curing system. For example, a perfluorinated polymer having a copolymerized unit of a nitrile-containing curing site monomer can be cured using a curing agent containing a mixture of an organotin curing agent and a peroxide in combination with a co-agent.

[0060] The co-agent (which may also be called a co-curing agent) may be composed of a polyunsaturated compound that can cooperate with the peroxide to bring about useful curing. The co-agent may be one or more of the following compounds: triallyl cyanurate, triallyl isocyanurate, tri(methylallyl) isocyanurate, tris(diallylamine)-s-triazine, triallyl phosphate, N,N-diallyl acrylamide, hexaallyl phosphoramide, N,N,N’,N’-tetraallyl malonamide, trivinyl isocyanurate, 2,4,6-trivinylmethyltrisiloxane, and tri(5-norbornene-2-methylene) cyanurate.

[0061] Other useful co-agents include bis-olefins. (See, for example, European Patent Nos. 0661304(A1), 0784064, and 0769521)

[0062] After homogeneously blending particles of a semi-crystalline fluoropolymer (i.e., modified PTFE) and particles of an amorphous fluoropolymer and any other components, the mixture can then be processed and shaped, such as by extrusion or molding, to form articles of various shapes, such as sheets, hoses, hose linings, O-rings, gaskets, or seals, composed of the compositions of the present disclosure. The shaped article can then be heated to cure the perfluoropolymer gum composition to form a cured elastomer article.

[0063] Pressurization (i.e., press curing) of the blended 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 minute 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 shaping of the composition. First, the mold can be coated with a release agent and pre-baked.

[0064] The vulcanized product can be post-cured in an oven at a temperature of about 140 °C to 350 °C, preferably about 200 °C to 330 °C, for about 1 hour to 24 hours or more, depending on the cross-sectional thickness of the sample. In thick portions, the temperature during post-curing usually gradually rises from the lower limit of the range to the desired maximum temperature. In one embodiment, the curing temperature exceeds 300 °C. In one embodiment, the curing temperature is higher than the melting point of the semi-crystalline fluoropolymer particles.

[0065] In one embodiment of the present disclosure, the composition containing a perfluoroelastomer gum or a cured perfluoroelastomer essentially does not contain metal cations, particularly cations of Na, K, Mg, and Al, and generally does not contain alkaline earth metal ions and alkali metal ions in general, and may contain them in an amount of less than 20 ppm (parts per million), or less than 10 ppm, or even less than 1 ppm. The concentrations of alkali ions and alkaline earth ions (Na, K, Li, Mg, Ba) and Al may be individually less than 1 ppm and in total less than 4 ppm. Other ions such as Fe, Ni, Cr, Cu, Zn, Mn, Co may be less than 4 ppm in total.

[0066] A particular advantage of the method of the present disclosure is that a blend of a fluoroelastomer and particles with a low content of fluorinated emulsifier acid can be prepared. Such blends may be particularly useful for applications in the semiconductor industry, because such applications require not only a low metal content, but also desirably do not leak acid from the fluoropolymer material in order to meet the high purity requirements in semiconductor processing and manufacturing. The perfluoroelastomer according to the present disclosure has a very small amount of fluorinated acid (e.g., extractable C8-C14 alkanoic acids) and its salts, e.g., less than 2000, 1000, 500, 100, 50, 25 ppb, or even less than 15 ppb (parts per billion) of fluorinated acid based on the weight of the polymer, which can be determined by extraction as described in U.S. Patent Application Publication No. 2019-0185599 (Hintzer et al.), which is incorporated herein by reference. The fluorinated acid has the general formula: Y-R f -Z-M [wherein Y represents hydrogen, Cl or F, R f represents a divalent linear or branched or cyclic perfluorinated or partially fluorinated saturated carbon chain having 8 to 14 carbon atoms, Z represents an acid group, e.g., -COO - or -SO3 - acid group, and M represents a cation containing H + .

[0067] Blends containing amorphous perfluoropolymers and particles of semi-crystalline fluoropolymers can be particularly useful in the manufacture of seals or molds, particularly in the manufacture or purification of products containing semiconductors, including semiconductor or etching equipment and vacuum evaporators. Examples of etching equipment include plasma etching equipment, reactive ion etching equipment, reactive ion beam etching equipment, sputter etching equipment, and ion beam etching equipment.

[0068] In one embodiment, a dry-blended perfluoroelastomer obtained by including a cooling step (e.g., cooling a semi-crystalline fluoropolymer to below its phase transition temperature, such as below 20, 10, 5 °C, or even below 0 °C) before incorporation can result in a filled perfluoropolymer gum having improved properties compared to the same perfluoroelastomer without the cooling step. For example, the perfluoroelastomers of the present disclosure can have improved plasma resistance, improved thermal stability, and / or improved flexibility.

[0069] This is because there are stringent requirements associated with the use of perfluoroelastomers in the semiconductor industry. To predict whether a perfluoroelastomer article is suitable for use, various test methods have been developed. One such test method is related to weight loss, where the perfluoroelastomer article is exposed to plasma and the weight loss is determined. In one embodiment, the perfluoroelastomer has a weight loss of less than 20, 10, 5%, or even less than 1% when exposed to plasma treatment.

[0070] Ideally, the semi-crystalline fluoropolymer particles should have good compatibility with the amorphous perfluoropolymer in order to enable a filled all-fluorinated elastomer composition having good aesthetics (e.g., a smooth and / or non-fibrillated product).

[0071] In one embodiment, the blend of semi-crystalline fluoropolymer particles and amorphous perfluoropolymer particles results in a blend having a melting point depression of at least 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 8.0, or even 10.0 compared to the melting point of the semi-crystalline fluoropolymer particles. In one embodiment, the blend comprising semi-crystalline fluoropolymer particles and amorphous perfluoropolymer has a melting point of 310, 320, 322, 324 °C, or even 326 °C or higher. In one embodiment, the blend comprising semi-crystalline fluoropolymer particles and amorphous perfluoropolymer has a melting point of up to 325, 326, 327, 328 °C, or even 329 °C.

[0072] The stability of the semi-crystalline fluoropolymer can be determined by analyzing the aggregated blend using thermogravimetric analysis that measures weight versus temperature. Then, the derivative of this curve is used to determine the temperature at which an inflection occurs. The inflection point temperature can be interpreted as the onset temperature of the decomposition of the semi-crystalline fluoropolymer. In one embodiment, a blend comprising semi-crystalline fluoropolymer particles and an amorphous perfluoropolymer has an inflection temperature higher than 500, 501, 502, 503, 504 °C, or even higher than 505 °C. In one embodiment, a blend comprising semi-crystalline fluoropolymer particles and an amorphous perfluoropolymer has an inflection temperature lower than 510, 509, 508, 507 °C, or even lower than 506 °C.

[0073] The recrystallization temperature refers to the temperature at which an amorphous semi-crystalline polymer crystallizes when cooled. Depending on the crystalline state, the polymer may have one or more recrystallization points. In one embodiment, a blend comprising semi-crystalline fluoropolymer particles and an amorphous perfluoropolymer has at least one recrystallization temperature less than 310, 309, 308, 307 °C, or even less than 305 °C.

Examples

[0074] Unless otherwise specified, all parts, percentages, ratios, etc. in the examples and other parts of the specification are by weight, and all reagents used in the examples were obtained from general chemical suppliers such as Sigma-Aldrich Company (Saint Louis, Missouri), etc., or were available, or could be synthesized by conventional methods.

[0075] The following abbreviations are used in this section: L = liter, mg = milligram, g = gram, kg = kilogram, cm = centimeter, mm = millimeter, wt% = weight percent, min = minute, h = hour, d = day, NMR = nuclear magnetic resonance, ppm = parts per million, sccm = standard cubic centimeter, °C = degree Celsius, mTorr = millitorr, RF = radio frequency, W = watt, mol = mole. The abbreviations of the materials used in this section, as well as the descriptions of the materials, are shown in Table 1. [Table 1]

[0076] Specific gravity

[0077] For Preparation Examples 2 and 3, the specific gravity was determined according to the protocol of DIN EN ISO 12086-2:2006-05.

[0078] Measurement of the particle size of the dry blend:

[0079] The particle size can be measured by the laser diffraction method according to ISO 13320 (2009).

[0080] Vinyl and allyl ether comonomer content

[0081] In the preparation example of melt-processable fluoropolymer particles, a thin film with a thickness of about 0.1 mm was prepared by molding a dried polymer solidified at 350 °C using a heated plate press. In the preparation example that is not melt-processable fluoropolymer particles, a thin film with a thickness of 0.3 mm to 0.4 mm was prepared by cold-compressing the polymer composition in a mold. Then, these films were scanned in a nitrogen atmosphere using a Nicolet DX510 FT-IR spectrometer. OMNIC software (ThermoFisher Scientific, Waltham, Mass.) was used for data analysis. In this specification, the CF2=CF-CF2-O-CF2-CF2-CF3 (MA-3) content reported in weight% was determined from the infrared band at 999 1 / cm and calculated as 1.24×(factor determined by solid-state NMR) times the ratio of the absorbance at 999 1 / cm to the absorbance of the reference peak located at 2365 1 / cm. The CF2=CF-O-CF2-CF2-CF3 (PPVE-1) content reported in weight% was determined from the infrared band at 993 1 / cm and calculated as 0.95× the ratio of the absorbance at 993 1 / cm to the absorbance of the reference peak located at 2365 1 / cm.

[0082] Melt Flow Index

[0083] For Preparation Example 1 (melt-processable semi-crystalline fluoropolymer), the melt flow index (MFI) was measured according to DIN EN ISO 1133-1:2012-03 with a supporting weight of either 2.16, 5.0, or 21.6 kg and reported in g / 10 min. The MFI was obtained using a standardized extrusion die with a diameter of 2.1 mm and a length of 8.0 mm. Unless otherwise specified, a temperature of 372 °C was applied.

[0084] Preparation Example 1 (Fluoropolymer A)

[0085] A 40 L kettle containing no oxygen was charged with 27 kg of deionized water, 390 g of a 30 wt% aqueous solution of an emulsifier, 100 g of PPVE-1, and 200 mbar of ethane (25 °C). The reactor was then heated to 75 °C and charged with TFE until a pressure of 10 bar was reached. Polymerization was initiated by feeding 3.0 g of ammonium persulfate (APS) (dissolved in 50 g of deionized water). TFE was continuously fed at a pressure of 10 bar (1 MPa). After a total of 5.6 kg of TFE, 280 g of PPVE-1 was fed to the reactor and an additional 1 g of APS was added. After 7.9 kg of TFE, polymerization was stopped. The latex had a solids content of 20.7 wt% and a d50 of 122 nm. The coagulated dry polymer had a PPVE-1 content of 0.8 wt% and an MFI of 18 g / 10 min (372 °C, 5 kg). The Tm of the fluoropolymer was determined as described above. The polymer had a Tm of 323 °C and a recrystallization point at 306 °C. The dry powder had a d50 of 470 μm.

[0086] Preparation Example 2 (Fluoropolymer B)

[0087] A 40 L kettle containing no oxygen was charged with 28 L of deionized water, 100 g of a 30 wt% aqueous solution of an emulsifier, 0.9 g of a 10 wt% aqueous solution of tert-butanol, 0.9 g of oxalic acid dihydrate, and 82 g of PPVE-1. The kettle was heated to 40 °C and TFE was fed to the reactor to obtain a pressure of 15 bar (1.5 MPa). Polymerization was initiated by adding 70 mg of pure KMnO4 (fed as a 0.04 wt% aqueous solution), and another 70 mg of KMnO4 was added continuously over the entire time (133 min). After adding 7.7 kg of TFE, 50 g of MV5CN CF2=CF-O-(CF2)5-CN, a mixture of 1 g of an emulsifier and 50 g of water was fed to the polymerization. After a total of 8.3 kg of TFE was fed to the reactor, polymerization was terminated. The latex had a solids content of 22.5 wt% and a d50 of 120 nm. The coagulated dry polymer had an SSG of 2.146, a PPVE content of 0.4 wt%, and 2236 cm -1The nitrile signal was visible. The Tm of the fluoropolymer having a Tm of 328 °C and a recrystallization of 303 °C was determined as described above. The dry powder had a d50 of 560 μm.

[0088] Preparation Example 3 (Fluoropolymer C)

[0089] A 40 L kettle without oxygen was charged with 28 kg of deionized water, 100 g of a 30 wt% aqueous emulsifier solution, 7 g of a 10 wt% aqueous tert-butanol solution, 0.9 g of oxalic acid dihydrate, and 50 g of MA-3 (C3F7-O-CF2-CF=CF2 available from Anles, St. Petersburg, Russia). The kettle was heated to 40 °C and TFE was added to reach 15 bar (1.5 MPa). Polymerization was initiated by feeding 76 mg of KMnO4 (as a 0.04 wt% aqueous solution) to the reactor. During the total run time (160 minutes), another 40 mg of KMnO4 was added. A total of 8.3 kg of TFE was added. The final latex had a solids content of 22.5 wt% and a d50 of 110 nm. The coagulated dry polymer had an SSG of 2.137 and an MA-3 content of 0.06 wt%. The Tm of the fluoropolymer having a Tm of 321 °C and a recrystallization point of 306 °C was determined as described above. The dry powder had a d50 of 430 μm.

[0090] Preparation Example 4

[0091] A 150 L kettle without oxygen was charged with 105 kg of deionized water, 2.8 kg of a 30 wt% aqueous emulsifier solution, 56 g of ammonium chloride, 235 g of ammonium nonafluorobutane-1-sulfinate (as a 34 wt% solution in water), and 214 g of MV5CN pre-emulsion. The MV5CN pre-emulsion consists of 25 wt% MV5CN (available from Anles, St. Petersburg, Russia), 0.4 wt% emulsifier (30 wt% aqueous solution), and 74.6 wt% water, and is prepared by mixing using a homogenizer. Then, the kettle was heated to 65 °C, PMVE was charged until a pressure of 10 bar was reached, and subsequently TFE was charged until a pressure of 14 bar was reached. Polymerization was initiated by supplying 890 g of a 20 wt% APS aqueous solution. PMVE and TFE were continuously supplied to the reactor, and 7.45 kg of MV5CN pre-emulsion was added until a total of 26.3 kg of TFE was added. After 295 minutes, a total of 24.1 kg of PMVE and 28.3 kg of TFE were added, and polymerization was stopped. The latex had a solids content of 32.6 wt% and a d50 of 77 nm. The solid polymer showed a Mooney viscosity of 57 Mooney units and was shown to have approximately 52.4 wt% TFE, 43.7 wt% PMVE, and 3.9 wt% CF2=CFO(CF2)5CN.

[0092] Examples 1 to 7, and Comparative Examples 1 and 2

[0093] The perfluoroelastomer compound was prepared using a 6-inch (15.24 cm) two-roll mill by kneading the amorphous perfluoropolymer with the semi-crystalline fluoropolymer in the amounts shown in Tables 3 and 4. In Examples 1 and Comparative Example 1, TFM 2001Z and PFA 6503NAZ were stored in a -20 °C freezer for at least 1 day and then added to the band while continuing mixing. For all of Examples 1 to 7 and Comparative Examples 1 and 2, for a part of each blend sample, milling and melting point values (T mAfter measuring ([0]), the compound was visually inspected. In Example 1 and Comparative Example 1, no significant fibrillation was observed during mixing. The melting point values are included in Tables 3 and 4. The visual inspection results for Examples 2 to 7 and Comparative Example 2 are included in Table 4.

[0094] As shown in Tables 3 and 5, a part of each of Example 1, Comparative Example 1, and the pulverized blends A to D of the pulverized blend was further kneaded on a two-roll mill to incorporate Catalyst A. Table 3 includes the results of cure rheology measurement and plasma resistance measurement. Table 4 includes the results of elastic modulus, the appearance of the pulverized sheet, the results of cure rheology measurement, and the results of composition set measurement values. The procedures for elastic modulus, cure rheology, plasma resistance, and compression set measurement are described below.

[0095] Melting point, glass transition, and recrystallization of the kneaded sample

[0096] Melting point (T m ) and glass transition temperature (T g ) were determined according to ASTM D793-01 and ASTM E1356-98 by a TA Instrument differential scanning calorimetry DSC Q2000 under a nitrogen stream. A DSC scan was obtained from -85°C to 350°C at a scanning rate of 10°C / min. The first heat cycle started at -85°C and was heated to 350°C at 10°C / min. The cooling cycle started at 350°C and was cooled to -85°C at 10°C / min. The second heat cycle started at -85°C and was heated to 350°C at 10°C / min. The DSC thermogram was obtained from the second heating of the heating / cooling / heating cycle, and T m was determined. The peak of the recrystallization temperature was obtained from the cooling scan after the first heat scan.

[0097] Inflection point temperature and semi-crystalline fluoropolymer blend ratio

[0098] The inflection point temperature was determined from the derivative curve using TGA (TGA Q500 by TA Instruments) in accordance with ASTM E1131-08. The sample size for the test was 10.0 ± 1 mg. The sample was heated to 650 °C at 10 °C / min under a nitrogen flow and then further heated to 800 °C at 10 °C / min under an air flow. The first derivative curve of the weight loss plotted against temperature showed two maxima. The temperature at which the minimum occurred between these two maxima was taken as the inflection point indicating the start of the decomposition of the semi-crystalline fluoropolymer. The inflection points are shown in Table 3. The semi-crystalline fluoropolymer blend ratio was determined as the ratio of the weight lost at a temperature higher than the inflection point from the weight loss curve to the total weight loss of the sample expressed as a percentage. The semi-crystalline fluoropolymer blend ratios are shown in Table 3.

[0099] The ground blends of the above Examples and Comparative Examples were kneaded as follows: Using a 6-inch (15.24 cm) two-roll mill, 100 g of Blend 1 with 1.1 g of Catalyst A was prepared. The compounds were characterized by measuring the elastic modulus, visual observation of the ground sheet, cure rheology, and compression set according to the procedures described below.

[0100] Visual inspection of the compound

[0101] After mixing on the mill, the blend was removed from the roll by cutting. The appearance of the resulting sheet was visually inspected. When fibrillation of the perfluoropolymer was observed during mixing, the surface appeared significantly rough. The visual observations for each sample are reported in Table 4.

[0102] Elastic modulus and frequency sweep of the kneaded sample

[0103] The elastic modulus at 100 °C was determined using a rheometer (RPA 2000 manufactured by Alpha technologies, Akron, OH) from the storage elastic modulus (G’) obtained from ASTM 6204-07, part A, with a strain of 7% and a frequency sweep of 01, 2.0, and 20 Hz. The sample size for the test was 7.0 ± 0.1 grams. A preliminary conditioning step was performed at 0.5 Hz, 62.8% strain, and 100 °C for 5 minutes prior to the elastic modulus measurement. The results are reported in Table 4.

[0104] Cure rheology of the kneaded sample

[0105] The cure characteristics of Examples 1, A, B, C, and D, and Comparative Example 1 were measured using an Alpha Technologies Rubber Process Analyzer equipped with a moving die rheometer (MDR) mode under conditions corresponding to ASTM D5289-07. The cure rheology test was performed on the uncured kneaded sample at 160 °C or 165 °C without preheating, with an elapsed time of 15 minutes or 12 minutes, and using an arc of 0.5 degrees. The minimum torque (M L ), and the flat region or maximum torque (M H ) were measured if they could not be obtained, and the highest torque (M H ) reached during a specific period was also measured. Also, the time (t L 2) when the torque increased by 2 units beyond M s , the time (t’10) when the torque reached a value equal to M L + 0.1(M H - M L ), the time (t’50) when the torque reached a value equal to M L + 0.5(M H - M L ), and the time (t’90) when the torque reached M L + 0.9(M H - M L ) were also measured.

[0106] Visual inspection of the compound

[0107] After mixing on a mill, the blend was removed from the roll by cutting. The appearance of the resulting sheet was visually inspected. The visual appearance of the entire sheet was reported as either a smooth or a rough appearance. The presence of fibrillation was determined by visually inspecting the sheet for an appearance with no white lines, few white lines, or a significant amount of white lines in the sheet. The visual observations for each sample are reported in Table 3.

[0108] Molded O-rings and compression set tests

[0109] O-rings (214, AMS AS568) were molded at 160 °C for 15 minutes or at 165 °C for 10 minutes. The press-cured O-rings were post-cured with the following step-curing procedure.

[0110] The first step-curing started at room temperature and was raised to 150 °C over 2 hours. It was held at 150 °C for 7 hours. The second step-curing started at 150 °C and was raised to 300 °C or 325 °C over 2 hours. It was held at 300 °C or 325 °C for 8 hours. Then the cooling process started at 300 °C or 325 °C and was cooled to room temperature over 2 hours.

[0111] The compression set of the post-cured O-rings was tested at 300 °C for 70 hours with an initial strain of 25% in accordance with ASTM D395-03 Method B and ASTM D1414-94. The results are reported as a percentage.

[0112] Plasma tests

[0113] The post-cured O-rings were tested for plasma resistance using a Plasma Pod (available from JLS Designs Ltd, UK). Half of the O-ring was placed in the center between the radio frequency electrodes, and plasma irradiation was carried out under a gas flow of only oxygen or a total of 30 sccm of oxygen and CF4 in a ratio of 9:1. The pressure was 225 millitorr and the RF power was 200 W. After 1 hour of exposure to the plasma, the weight loss was measured and calculated using the following equation. The plasma test results are

[0114] It is summarized in Table 2.

Number

Table 2

Table 3

Table 4

[0115] Modifications and changes to the present invention that are predictable to those skilled in the art and do not depart from the scope and spirit of the present invention will be apparent. The present invention is not limited to the embodiments described in this application for illustrative purposes. If there is any inconsistency or contradiction between the description in this specification and the disclosure in any document described or incorporated by reference herein, the description in this specification shall prevail. The present invention includes the following aspects. (1) A dry powder blend comprising: (i) an amorphous perfluoropolymer containing a curing site selected from the group consisting of -CN, -I, and -Br; and (ii) a plurality of semi-crystalline fluoropolymer particles, wherein the semi-crystalline fluoropolymer particles comprise a tetrafluoroethylene copolymer containing at least one additional fluorinated monomer in an amount of 1 wt% or less, and the semi-crystalline fluoropolymer particles have (i) a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) are not melt processable and have a standard specific gravity of less than 2.200. (2) The dry blend according to item 1, wherein the blend has a melting temperature, and the melting temperature of the blend is at least 3 °C lower than the melting point of the semi-crystalline fluoropolymer particles. (3) The dry blend according to item 1 or 2, wherein the melting temperature of the blend is greater than 310 °C and less than 329 °C. (4) The dry blend according to any one of items 1 to 3, wherein the melting temperature of the blend is greater than 310 °C and less than 323 °C. (5) The dry powder blend according to any one of items 1 to 4, wherein the dry powder blend has a decomposition temperature, and the decomposition temperature is 500 °C or higher and at most 510 °C. (6) The dry powder blend according to any one of items 1 to 5, wherein the dry powder blend has at least one recrystallization point, and the at least one recrystallization point is less than 310 °C. (7) The dry powder blend according to any one of items 1 to 6, wherein the dry powder blend contains at least 10 wt% to a maximum of 30 wt% of the semi-crystalline fluoropolymer particles. (8) The dry powder blend according to any one of items 1 to 7, wherein the amount of the at least one additional fluorinated monomer is 0.1 wt% or less in the tetrafluoroethylene copolymer. (9) The at least one additional fluorinated monomer is selected from hexafluoropropylene and the general formula: R f -O-(CF 2 ) m CF=CF 2 [wherein m is 0 or 1, and Rf represents a perfluoroalkyl residue containing at least one carbon atom, which may have at least one in-chain oxygen atom intervening], and is selected from at least one of the unsaturated perfluorinated ethers. The dry powder blend according to any one of items 1 to 8. (10) The dry powder blend according to any one of items 1 to 9, wherein the tetrafluoroethylene copolymer is a core-shell particle. (11) The dry powder blend according to any one of items 1 to 10, wherein the amorphous perfluoropolymer has a glass transition temperature of less than 10 °C. (12) The amorphous perfluoropolymer is a perfluoroolefin and a general formula: R f -O-(CF 2 ) mCF=CF 2 [wherein m is 0 or 1, and Rf represents a perfluoroalkyl residue containing at least one carbon atom, which may have at least one chain oxygen atom intervening therein], the dry powder blend according to any one of items 1 to 11, which is derived from an unsaturated perfluorinated ether selected from the group consisting of: (13) The dry powder blend according to item 12, wherein the perfluoroolefin is tetrafluoroethylene, hexafluoropropylene, or a combination thereof. (14) The unsaturated perfluorinated ether is perfluoro(2-propoxypropyl vinyl) ether (PPVE-2), perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), perfluoro(3-methoxy-n-propyl vinyl) ether (MV-31), perfluoro(2-methoxy-ethyl vinyl) ether, perfluoro(n-propyl vinyl) ether (PPVE-1), perfluoro(n-propyl allyl) ether (MA-3), and F 3 C-(CF 2 ) 2 -O-CF(CF 3 )-CF 2 -O-CF(CF 3 )-CF 2 -O-CF=CF 2 (PPVE-3), the dry powder blend according to any one of items 12 to 13, which is selected from the group consisting of: (15) The powder blend according to any one of items 1 to 14, wherein the amorphous perfluoropolymer contains a curing site selected from at least one of bromine, iodine, and nitrile. (16) The powder blend according to any one of items 1 to 15, wherein the second fluorinated monomer is a nitrile-containing perfluorinated vinyl ether. (17)A curable perfluoropolymer composition comprising a homogeneous dry blend of (i) an amorphous perfluoropolymer and (ii) semi-crystalline fluoropolymer particles, wherein the semi-crystalline fluoropolymer particles comprise a tetrafluoroethylene copolymer containing at least one additional fluorinated monomer of 1 wt% or less, and the semi-crystalline fluoropolymer particles have (i) a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) are not melt processable and have a standard specific gravity of less than 2.200. (18)A cured perfluoroelastomer comprising a perfluoropolymer filled with semi-crystalline fluoropolymer particles, wherein the semi-crystalline fluoropolymer particles comprise a tetrafluoroethylene copolymer containing at least one additional fluorinated monomer of 1 wt% or less, and the semi-crystalline fluoropolymer particles have (i) a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) are not melt processable and have a standard specific gravity of less than 2.200. (19)A method for manufacturing a fluoroelastomer article, comprising providing the dry blend according to any one of items 1 to 18, shaping the dry blend, and curing the shaped dry blend to form the fluoroelastomer article. (20)The method according to item 19, wherein the curing is carried out at a temperature higher than 300 °C. (21)The method according to item 20, wherein the curing is carried out at a temperature higher than the melting point of the semi-crystalline fluoropolymer particles. (22)A method for manufacturing a curable perfluoroelastomer, (a) obtaining (i) an amorphous perfluoropolymer and (ii) particles of a semi-crystalline tetrafluoroethylene copolymer containing at least one additional fully fluorinated monomer of 1 wt% or less, wherein the semi-crystalline fluoropolymer particles have (i) a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) are not melt processable and have a standard specific gravity of less than 2.200, (b) contacting the amorphous perfluoropolymer with the particles, (c) dry blending the amorphous perfluoropolymer and the particles to form a curable perfluoroelastomer, and a method comprising the steps of:

Claims

1. (i) an amorphous perfluoropolymer comprising a curing site selected from the group consisting of -CN, -I, and -Br; and (ii) a plurality of semi-crystalline fluoropolymer particles, A dry powder blend comprising: The semi-crystalline fluoropolymer particles are core-shell particles comprising a core of one composition and a shell of a composition different from the core; The semi-crystalline fluoropolymer particles comprise a tetrafluoroethylene copolymer, and the tetrafluoroethylene copolymer is derived from tetrafluoroethylene and a perfluorinated vinyl ether monomer, a perfluorinated allyl ether monomer, or a combination thereof that is greater than 0 wt% and less than or equal to 1 wt% as measured by Fourier transform infrared spectroscopy; The semi-crystalline fluoropolymer particles, (i) have a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min, or (ii) are not melt processable and have a standard specific gravity of less than 2.200, a dry powder blend.

2. The dry powder blend according to claim 1, wherein the blend has a melting temperature, and the melting temperature of the blend is at least 3 °C lower than the melting point of the semi-crystalline fluoropolymer particles.

3. The dry powder blend according to claim 2, wherein the melting temperature of the blend is greater than 320 °C and less than 329 °C.

4. The dry powder blend according to any one of claims 1 to 3, wherein the dry powder blend has a decomposition temperature, and the decomposition temperature is 500 °C or higher and at most 510 °C.

5. The dry powder blend according to any one of claims 1 to 4, wherein the dry powder blend has at least one recrystallization point, and the at least one recrystallization point is less than 310 °C.

6. The dry powder blend according to any one of claims 1 to 5, wherein the dry powder blend comprises at least 10 wt% to a maximum of 30 wt% of the semi-crystalline fluoropolymer particles.

7. The dry powder blend according to any one of claims 1 to 6, wherein the amount of the perfluorinated vinyl ether monomer, the perfluorinated allyl ether monomer, or a combination thereof is 0.1 wt% or less in the tetrafluoroethylene copolymer.

8. The perfluorinated vinyl ether monomer, the perfluorinated allyl ether monomer, or a combination thereof is hexafluoropropylene and the general formula: R ｆ -O-(CF ２ ) ｍ CF=CF ２ [wherein m is 0 or 1, and Rf represents a perfluoroalkyl residue containing at least one carbon atom, in which at least one in-chain oxygen atom may be interposed] The dry powder blend according to any one of claims 1 to 7, which is selected from at least one of the unsaturated perfluorinated ethers.

9. The dry powder blend according to any one of claims 1 to 8, wherein the semi-crystalline fluoropolymer particles are core-shell particles including a core containing a tetrafluoroethylene homopolymer or a tetrafluoroethylene copolymer and a shell containing a polymer of tetrafluoroethylene modified with a perfluorinated vinyl ether, a perfluorinated allyl ether, or a combination thereof.

10. The dry powder blend according to any one of claims 1 to 9, wherein the amorphous perfluoropolymer has a glass transition temperature of less than 10 °C.

11. The dry powder blend according to any one of claims 1 to 10, wherein the powder blend contains C8-C14 alkanoic acid of less than 500 ppb.

12. (i) an amorphous perfluoropolymer; (ii) semi-crystalline fluoropolymer particles; A curable perfluoropolymer composition comprising a homogeneous dry blend of, wherein the semi-crystalline fluoropolymer particles are core-shell particles including a core of one composition and a shell of a composition different from the core, wherein the semi-crystalline fluoropolymer particles contain a tetrafluoroethylene copolymer, and the tetrafluoroethylene copolymer is derived from tetrafluoroethylene and a perfluorinated vinyl ether monomer, a perfluorinated allyl ether monomer, or a combination thereof, which is more than 0 wt% and 1 wt% or less as measured by Fourier transform infrared spectroscopy, wherein the semi-crystalline fluoropolymer particles (i) have a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min, or (ii) are not melt-processable and have a standard specific gravity of less than 2.200, a curable perfluoropolymer composition.

13. A cured perfluoroelastomer containing a perfluoropolymer having semi-crystalline fluoropolymer particles dispersed therein, wherein the semi-crystalline fluoropolymer particles are core-shell particles including a core of one composition and a shell of a composition different from the core, The semi-crystalline fluoropolymer particles include a tetrafluoroethylene copolymer, the tetrafluoroethylene copolymer being derived from tetrafluoroethylene and a perfluorinated vinyl ether monomer, a perfluorinated allyl ether monomer, or a combination thereof, measured by Fourier transform infrared spectroscopy and being more than 0 wt% and not more than 1 wt%, and the semi-crystalline fluoropolymer particles having (i) a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) not being melt processable and having a standard specific gravity of less than 2.200, a cured perfluoroelastomer.

14. A method for manufacturing a fluoroelastomer article, comprising providing the dry blend according to any one of claims 1 to 11, shaping the dry blend, and curing the shaped dry blend to form the fluoroelastomer article.

15. A method for manufacturing a curable perfluoroelastomer, (a) obtaining (i) an amorphous perfluoropolymer and (ii) particles of a semi-crystalline tetrafluoroethylene copolymer, the particles of the semi-crystalline tetrafluoroethylene copolymer being core-shell particles including a core of one composition and a shell of a composition different from the core, the particles of the semi-crystalline tetrafluoroethylene copolymer being derived from tetrafluoroethylene and a perfluorinated vinyl ether monomer, a perfluorinated allyl ether monomer, or a combination thereof, measured by Fourier transform infrared spectroscopy and being more than 0 wt% and not more than 1 wt%, and obtaining the particles of the semi-crystalline tetrafluoroethylene copolymer having (i) a melt flow index (at 372 °C, 2.16 kg) of less than 50 g / 10 min or (ii) not being melt processable and having a standard specific gravity of less than 2.200, (b) contacting the amorphous perfluoropolymer with the particles in the presence or absence of a small amount of water and in the presence or absence of a small amount of a solvent to form the curable perfluoroelastomer.

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