Low-reactivity hydrocarbon dispersants in aqueous polymerization of fluoropolymers

Abstract

A method for polymerizing at least one fluorinated monomer in an aqueous medium containing an initiator and a hydrocarbon dispersant to form an aqueous dispersion of fluorinated polymer particles. The hydrocarbon dispersant comprises a compound of formula I: R-(XZ). n (I), wherein R is a hydrophobic hydrocarbon moiety comprising one or more saturated or unsaturated, acyclic or cyclic aliphatic groups, the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in the one or more aliphatic groups is at least about 70%, the hydrophobic moiety is free of siloxane units; wherein each X can be the same or different and represents an ionic hydrophilic moiety; wherein each Z can be the same or different and represents one or more counterions of the ionic hydrophilic moiety; and wherein n is 1 to 3.

Description

Technical Field

[0001] This invention relates to aqueous emulsion polymerization of fluoropolymers, and more particularly to the use of low-reactivity hydrocarbon dispersants in aqueous emulsion polymerization of fluoropolymers. Background Technology

[0002] Hydrocarbon surfactants have been disclosed as alternatives to stabilizing surfactants in the aqueous emulsion polymerization of fluoropolymers. Various methods of using hydrocarbon surfactants have been disclosed for non-perfluorinated fluoropolymers, i.e., those containing hydrocarbon monomers such as olefins or hydrocarbon-fluorinated monomers such as vinylidene fluoride (VF2). For example, U.S. Patent 7,122,610 (Wille et al.) demonstrates the use of certain alkane sulfonates, sulfones, and disulfones in polymerization reactions to form non-elastomeric fluoropolymers containing at least 71% by weight of vinylidene fluoride (VF2). U.S. Patents 8,080,621, 8,158,734, and 8,338,518 (Amin-Sanayei et al.) disclose the use of various nonionic surfactants containing segments of polyethylene glycol, polypropylene glycol, and / or polybutanediol for the polymerization of VF2 homopolymers and copolymers. U.S. Patents 6,512,063 and 7,521,513 (Tang) disclose the use of hydrocarbon anionic surfactants such as sodium octyl sulfonate for polymerizing fluorinated elastomers containing VF2 or olefin monomers.

[0003] However, problems arise when attempting to use hydrocarbon surfactants in the manufacture of perfluoropolymers. For the polymerization of polytetrafluoroethylene (PTFE), Puts et al., in Chem. Rev. 2019, 119, 1763-1805, page 1779, report numerous problems with hydrocarbon surfactants. The reference states:

[0004] "The main problem with using hydrocarbon dispersants (surfactants) is the possibility of forming low molecular weight polymers due to hydrogen abstraction from the grown fluorine-containing large groups. In addition, hydrocarbons have limited affinity for TFE and its polymers, so the dispersing effect of hydrocarbon reagents is unsatisfactory."

[0005] Puts et al. also described the instability of dispersions and undesirable large dispersion particle sizes as problems associated with using hydrocarbon surfactants in PTFE polymerization. Because hydrocarbon surfactants readily react with initiators and / or growing fluoropolymer radicals during polymerization, these reactions slow down the polymerization rate or can completely prevent polymerization and significantly reduce the average molecular weight of the polymerized product.

[0006] For perfluoropolymers such as polytetrafluoroethylene (PTFE) and copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP), as well as copolymers of TFE with perfluoro(alkyl vinyl ethers), methods have been disclosed that use hydrocarbon surfactants instead of fluorinated surfactants. These methods employ additional process steps to control the difficulties associated with using hydrocarbon surfactants. WO2012 / 064846 A1, WO2012 / 064858 A1, and WO2012 / 064841 A1 (Brothers et al.) disclose methods using hydrocarbon surfactants that employ a nucleation step early in the process, followed by a stabilization step utilizing delayed addition and metering of the hydrocarbon surfactant during polymerization. Brothers et al. also disclosed treatments to reduce the telomerization properties of hydrocarbon surfactants. Although the methods employed by Brothers et al., using additional process steps and / or treatments with hydrocarbon surfactants, have been very successful in manufacturing fluoropolymers including perfluoropolymers, their methods must be carefully controlled and cannot be used to operate in a manner similar to existing methods using fluorinated surfactants. Summary of the Invention

[0007] This invention is based on the discovery that a class of hydrocarbon dispersants exhibit low reactivity with polymerization initiators and / or fluoropolymer radicals grown in emulsion polymerization of fluoropolymers with fluorinated monomers. Embodiments of the method of this invention using low-reactivity hydrocarbon dispersants can provide polymerization rates suitable for commercial production, fluoropolymer dispersions with high solids content, and / or fluoropolymers with desired average molecular weights for commercial use. The benefits provided by this invention can be achieved with many different types of fluoropolymers, including perfluoropolymers. Furthermore, if desired, the method of this invention can be carried out as with existing methods using fluorinated surfactants, for example, by preloading the surfactant into the aqueous medium before or simultaneously with the start of polymerization.

[0008] According to the method of the present invention, at least one fluorinated monomer is polymerized in an aqueous medium containing an initiator and a hydrocarbon dispersant to form an aqueous dispersion of fluorinated polymer particles. The hydrocarbon dispersant comprises a compound of formula I:

[0009] R-(XZ) n I

[0010] Wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups, the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in the one or more aliphatic groups is at least about 70%, and the hydrophobic moiety does not contain siloxane units;

[0011] Each X can be the same or different and represents the hydrophilic part of the ion;

[0012] Each Z can be the same or different and represents one or more counter ions of the hydrophilic portion of the ion; and

[0013] Where n is between 1 and 3.

[0014] In one embodiment of the invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant is entirely aliphatic, and the hydrocarbon dispersant has a molecular weight of at least about 170 g / mol in the absence of the counterion Z.

[0015] In another embodiment of the invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant contains at least one aromatic group, and the hydrocarbon dispersant has a molecular weight of at least about 215 g / mol in the absence of the counterion Z.

[0016] Preferably, in the method of the present invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant contains no more than 3 consecutive CH2 groups, more preferably no more than 2 consecutive CH2 groups, and most preferably does not contain any consecutive CH2 groups.

[0017] Preferably, in the method of the present invention, the hydrophobic hydrocarbon portion comprises at least 3 CH3 groups, more preferably at least 4 CH3 groups. A preferred range for the number of CH3 groups in the hydrophobic hydrocarbon portion is 3 to 12.

[0018] The hydrophilic ionic moiety X is preferably selected from the group consisting of: acid groups and their salts, quaternary ammonium groups, amine oxide groups, and tetrazolium groups. In a preferred embodiment, the hydrophilic moiety and the counter ion XY are of formula -A. - -Y + The group, wherein A - It is a carboxylate, sulfonate, sulfate, phosphonate, or phosphate group, and Y is therein. + It is hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal, or alkaline earth metal. Most preferably, A... - It is a sulfonate group.

[0019] In a preferred embodiment of the invention, the hydrophobic hydrocarbon moiety is halogen-free. In another preferred embodiment, one or more aliphatic groups in the hydrophobic hydrocarbon moiety are acyclic or cyclic alkyl groups.

[0020] In another preferred embodiment, the hydrophobic hydrocarbon portion comprises one or more aromatic groups. In embodiments comprising one or more aromatic groups, the one or more aromatic groups have a Hammett σ+ value greater than about -1.0, preferably greater than about -0.8, and most preferably greater than about 0.

[0021] In embodiments comprising one or more aromatic groups, the hydrophobic hydrocarbon moiety preferably does not contain methyl groups directly bonded to the aromatic groups. It is also preferred in such embodiments that the hydrophobic hydrocarbon moiety does not contain benzyl hydrogen atoms. It is further preferred that the hydrophobic hydrocarbon moiety does not contain phenolic hydroxyl groups.

[0022] In a preferred embodiment of the invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant comprises 8 to 50 carbon atoms, preferably 10 to 40 carbon atoms, more preferably 12 to 30 carbon atoms, and most preferably 12 to 25 carbon atoms.

[0023] In a preferred embodiment of the invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant does not contain carbon-hydrogen bonds that have a bond dissociation energy of less than about 100 kcal / mol to generate hydrocarbon free radicals.

[0024] In a preferred embodiment of the invention, the hydrocarbon dispersant has a loss of less than about 10% by weight of tert-butyl peroxide.

[0025] In a preferred embodiment of the invention, the hydrocarbon dispersant comprises a substitution portion of the following formula:

[0026]

[0027] Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0028] In another preferred embodiment, the initiator contained in the aqueous medium in this method is an organic peroxide.

[0029] In a preferred embodiment of the invention, the hydrocarbon dispersant is a compound of formula II:

[0030]

[0031] Where R 2′ and R 2″ They are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 2′ and R 2″ The percentage of the total number of CH3, CH2, and CH groups in the group is at least about 70%, or R 2′ and R 2″ They can be joined together to form a saturated or unsaturated aliphatic ring that can contain ether or ester bonds, provided that the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in the ring is at least about 70%.

[0032] Where R 1It is hydrogen, methoxy, ethoxy, or phenoxy; and

[0033] Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0034] Preferably, in the compound of formula II, R 2 ′ and R 2 "is the same or different and is tert-butyl-, tert-butoxy, 2,3,3-trimethyl-2-butyl or 2,3,3-trimethyl-2-butoxy or -CO(O)C(CH3)3, and wherein R 1 It is hydrogen or methoxy, and where Y is hydrogen or methoxy. + It is hydrogen, ammonium, or alkali metal.

[0035] In another preferred embodiment, in the compound of formula II, R 2 ′ and R 2 "Is the same or different and is tert-butyl or 2,3,3-trimethyl-2-butyl, R" 1 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0036] In another preferred embodiment, in the compound of formula II, R 2 ′ and R 2 "Is the same or different and is tert-butyl or 2,3,3-trimethyl-2-butyl, R" 1 It is methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

[0037] In another preferred embodiment, in the compound of formula II, R 2 ′ and R 2 "All are tert-butyl, R" 1 It is hydrogen or methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

[0038] In a preferred embodiment of the invention, the hydrocarbon dispersant is a compound of formula III:

[0039]

[0040] Where R 3 R 4′ and R 4″ They are the same or different and are hydrogen or saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 3 R 4′ and R 4″The percentage of the total number of CH3, CH2, and CH groups in the group is at least about 70%, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0041] Preferably, in compounds of formula III, R 3 R 4′ and R 4″ They are the same or different and are hydrogen, tert-butyl, tert-butoxy, 2,3,3-trimethyl-2-butyl, or 2,3,3-trimethyl-2-butoxy, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0042] In a preferred embodiment, in the compound of formula III, R 3 It is tert-butyl or 2,3,3-trimethyl-2-butyl, R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0043] In another preferred embodiment, in the compound of formula III, R 3 It is tert-butyl, and R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0044] In another preferred embodiment, in the compound of formula III, R 4′ and R 4″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 3 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0045] In another preferred embodiment, in the compound of formula III, R 4′ and R 4″ For tert-butyl, R 3 It is hydrogen, and Y + It consists of hydrogen, ammonium, and alkali metals.

[0046] According to the present invention, the aqueous composition comprises a hydrocarbon dispersant of formula II:

[0047]

[0048] Where R 2′ and R 2″ They are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 2 and R 3 The percentage of the total number of CH3, CH2 and CH groups in the group is at least about 70%, or they can be joined together to form a saturated or unsaturated aliphatic ring that can contain ether bonds or ester bonds, provided that the percentage of the total number of CH3 groups relative to the total number of CH3, CH2 and CH groups in the ring is at least about 70%.

[0049] Where R 1 It is hydrogen, methoxy, ethoxy, or phenoxy; and

[0050] Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0051] Preferably, in the aqueous composition of the compound of formula II, R 2′ and R 2″ It is the same or different and is tert-butyl-, tert-butoxy, 2,3,3-trimethyl-2-butyl, 2,3,3-trimethyl-2-butoxy or -CO(O)C(CH3)3, and wherein R 1 It is hydrogen, methoxy, or phenoxy, and wherein Y is hydrogen, methoxy, or phenoxy. + It is a cation selected from the group consisting of hydrogen, ammonium, or alkali metals.

[0052] Preferably, in the aqueous composition of the compound of formula II, R 2′ and R 2″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 1 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0053] In a preferred embodiment, in the compound of formula II, R 2′ and R 2″They are the same or different and are tert-butyl- or 2,3,3-trimethyl-2-butyl, and R 1 It is a methoxy group.

[0054] In a preferred embodiment, in the compound of formula II, R 2′ and R 2″ All are tert-butyl, R 1 It is hydrogen or methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

[0055] The present invention also provides a compound of formula III:

[0056]

[0057] Where R 3 R 4′ and R 4″ They are the same or different and are hydrogen or saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 3 R 4′ and R 4″ The percentage of the total number of CH3, CH2, and CH groups in the group is at least about 70%, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and

[0058] Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0059] This invention provides preferred compounds, wherein R 3 R 4′ and R 4″ They are the same or different and are hydrogen, tert-butyl, tert-butoxy, 2,3,3-trimethyl-2-butyl, or 2,3,3-trimethyl-2-butoxy, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and Y+ It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0060] In a preferred embodiment, R 3 It is tert-butyl or 2,3,3-trimethyl-2-butyl, R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0061] In another preferred embodiment, R 3 For tert-butyl, R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0062] In another preferred embodiment, R 4′ and R 4″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 3 It is hydrogen, and Y + It consists of hydrogen, ammonium, and alkali metals.

[0063] In another preferred embodiment, R 4′ and R 4″ For tert-butyl, R 3 It is hydrogen, and Y + It consists of hydrogen, ammonium, and alkali metals. Attached Figure Description

[0064] Figure 1 This is a graphical representation of the effect of increasing the dispersant concentration on the monomer feed rate for the selected comparative dispersant and the dispersant of the present invention in the method for polymerizing fluorinated elastomers as shown in polymerization example 14. Detailed Implementation

[0065] Fluorinated monomers / fluorinated polymers

[0066] The method of this invention polymerizes fluorinated monomers in an aqueous medium to form an aqueous dispersion of fluorinated polymer particles. "Fluorinated monomer" refers to a monomer containing fluorine, preferably an olefin monomer having at least one fluorine or fluoroalkyl group attached to a double carbon bond. Other unfluorinated monomers may be used in the polymerization.

[0067] The fluorinated monomer and the fluorinated polymer obtained therefrom preferably contain at least 35% by weight of fluorine, more preferably at least 50% by weight of fluorine. Preferred fluorinated monomers for preparing the fluorinated polymers according to the invention may be selected from the group consisting of: tetrafluoroethylene (TFE), hexafluoropropylene (HFP), trifluorochloroethylene (CTFE), trifluoroethylene, hexafluoroisobutylene, perfluoroalkylethylene, fluorovinyl ether, vinyl fluoride (VF), vinylidene fluoride (VF2), perfluoro-2,2-dimethyl-1,3-m-dioxacyclopentene (PDD), perfluoro-2-methylene-4-methyl-1,3-dioxacyclopentane (PMD), perfluoro(allyl vinyl ether), and perfluoro(butenyl vinyl ether), and mixtures thereof. A preferred perfluoroalkylethylene monomer is perfluorobutylethylene (PFBE). Preferred fluorovinyl ethers include perfluoro(alkyl vinyl ether) monomers (PAVE), such as perfluoro(propyl vinyl ether) (PPVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(methyl vinyl ether) (PMVE). Non-fluorinated olefin comonomers such as ethylene (E) and propylene (P) can be copolymerized with fluorinated monomers.

[0068] Fluorovinyl ethers also include those that can be used to introduce functional groups into fluoropolymers. These include CF2=CF-(O-CF2CFR). f ) a -O-CF2CFR′ f SO2F, where R f and R′ f The monomer is independently selected from F, Cl, or a perfluorinated alkyl group having 1 to 10 carbon atoms, where a = 0, 1, or 2. This type of monomer is disclosed in U.S. Patent 3,282,875 (CF2 = CF-O-CF2CF(CF3)-O-CF2CF2SO2F, perfluorinated (3,6-dioxa-4-methyl-7-octenylsulfonyl fluoride)) and U.S. Patents 4,358,545 and 4,940,525 (CF2 = CF-O-CF2CF2SO2F). Another example is the methyl ester of CF2 = CF-O-CF2-CF(CF3)-O-CF2CF2CO2CH3, perfluorinated (4,7-dioxa-5-methyl-8-nonenic acid), disclosed in U.S. Patent 4,552,631. Similar fluorovinyl ethers having nitrile, cyanate, carbamate and phosphonic acid functional groups are disclosed in U.S. Patents 5,637,748, 6,300,445 and 6,177,196.

[0069] In a preferred method according to the invention, the method produces a dispersion of perfluoropolymer particles. "Perfluoropolymer" means that the monovalent substituents on the carbon atoms of the chains or backbone forming the polymer are all fluorine atoms, except for the CH moiety produced by a small amount of comonomer or the CH moiety in the end or side group structure. Preferably, the comonomer, end group, or side group structure will impart no more than 2% by weight of CH moiety relative to the total weight of the perfluoropolymer, more preferably no more than 1% by weight of CH moiety. Preferably, the hydrogen content (if any) of the perfluoropolymer is no more than 0.2% by weight based on the total weight of the perfluoropolymer. A preferred group of perfluoropolymers is selected from polytetrafluoroethylene, modified polytetrafluoroethylene, and melt-manufacturable copolymers comprising 40 mol%-99 mol% tetrafluoroethylene units and 1 mol%-60 mol% of at least one other perfluoromonomer.

[0070] This method is particularly useful for preparing high molecular weight polytetrafluoroethylene (PTFE), including modified PTFE, in fine powder and dispersion form. PTFE refers to (a) polymerized tetrafluoroethylene itself without any significant comonomers, i.e., a homopolymer, and (b) modified PTFE, which is a copolymer of TFE with such low concentrations of comonomers that the melting point of the resulting polymer does not decrease substantially below the melting point of PTFE. Modified PTFE contains a small amount of comonomer modifier that reduces crystallinity to improve film-forming ability during baking (fusion). Examples of such monomers include perfluoroolefins, notably hexafluoropropylene (HFP) or perfluoro(alkyl vinyl ether) (PAVE), trichlorochlorofluoroethylene (CTFE), perfluorobutylethylene (PFBE), or other monomers that introduce bulky side groups into the polymer molecule, wherein the alkyl group contains 1 to 5 carbon atoms, with perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE) being preferred. Based on the total weight of TFE and comonomers present in PTFE, the concentration of such comonomers is preferably less than 1% by weight, more preferably less than 0.5% by weight. A minimum amount of at least about 0.05% by weight is preferably used to achieve a significant effect. When separated from the dispersion in powder form, high molecular weight PTFE (and modified PTFE), referred to as PTFE fine powder, typically has a concentration of at least about 1 × 10⁻⁶. 6 Pa·s, and preferably at least 1×10 8 The melt creep viscosity is measured in Pa·s, and at this high melt viscosity, the polymer does not flow significantly in the molten state and is therefore not a melt-processable polymer. Measurements of the melt creep viscosity of fine PTFE powder are disclosed in column 4 of U.S. Patent 7,763,680. The high melt viscosity of PTFE is due to its extremely high molecular weight (Mn), for example, at least 10. 6PTFE is also characterized by its high melting temperature of at least 330°C on initial heating. When the melt flow rate (MFR) is measured at 372°C using a 5kg weight according to ASTM D 1238, the non-melt flowability of PTFE due to its extremely high melt viscosity results in a no-melt flow condition, i.e., an MFR of 0. The high molecular weight of PTFE is characterized by measuring its standard specific gravity (SSG). The SSG measurement procedure (ASTM D 4894, also described in US Patent 4,036,802) involves sintering a self-standing SSG sample (without a container) above its melting temperature without altering the dimensions of the SSG sample. The SSG sample does not flow during sintering.

[0071] The method of this invention can also be used to produce low molecular weight PTFE by direct polymerization to low molecular weight. Low molecular weight PTFE is commonly referred to as PTFE ultrafine powder to distinguish it from the aforementioned high molecular weight PTFE fine powder, which has a significantly higher molecular weight. The molecular weight of PTFE ultrafine powder is relatively low compared to PTFE fine powder, i.e., the molecular weight (Mn) is typically around 10. 4 Up to 10 5 Within the range. This lower molecular weight of PTFE ultrafine powder results in its flowability in the molten state, which is the opposite of PTFE fine powder that cannot melt flow. PTFE ultrafine powder has melt flowability, characterized by a melt flow rate (MFR) of at least 0.01 g / 10 min, preferably at least 0.1 g / 10 min, and more preferably at least 5 g / 10 min, and even more preferably at least 10 g / 10 min, as measured on a molten polymer at 372°C using a 5 kg weight, according to ASTM D 1238.

[0072] This invention can also be used to prepare fluoropolymers that are also melt-manufacturable and melt-processable. Melt-processable means that the fluoropolymer can be processed in a molten state, i.e., using conventional processing equipment such as extruders and injection molding machines to form molded articles such as films, fibers, and tubes from the melt. Melt-manufacturable means that the resulting manufactured articles exhibit sufficient strength and toughness for their intended purpose. This sufficient strength is characterized by the fluoropolymer itself exhibiting an MIT (Mean Time Tolerance) flexural life of at least 1000 cycles, preferably at least 2000 cycles, as disclosed in U.S. Patent 703,185. The strength of the fluoropolymer is indicated by its resistance to breakage.

[0073] Examples of such melt-processable fluoropolymers include homopolymers such as polychlorotrifluoroethylene and polyvinylidene fluoride (PVDF), or tetrafluoroethylene (TFE) and copolymers of at least one fluorinated comonomer (comonomer), which are typically present in sufficient quantities in the polymer to lower the melting point of the copolymer to substantially below the melting point of PTFE, for example, to a melting temperature not exceeding 315°C.

[0074] Melt-processable TFE copolymers typically incorporate a certain amount of comonomer into the copolymer to provide a melt flow rate (MFR) of 0.1 to 200 g / 10 min, as measured using a 5 kg weight on the molten polymer according to ASTM D-1238, and a melt temperature that serves as a standard for the particular copolymer. The MFR will preferably be in the range of 1 to 100 g / 10 min, most preferably from about 1 to about 50 g / 10 min. Other melt-processable fluoropolymers are copolymers of ethylene (E) or propylene (P) with TFE or CTFE, with particular note being ETFE and ECTFE.

[0075] Preferred melt-processable copolymers used in the practice of this invention comprise at least 40 mol% to 99 mol% of tetrafluoroethylene units and 1 mol% to 60 mol% of at least one other monomer. Other melt-processable copolymers are those containing 60 mol% to 99 mol% of TFE units and 1 mol% to 40 mol% of at least one other monomer. Preferred comonomers for forming perfluoropolymers with TFE are perfluoromonomers, preferably perfluoroolefins having 3 to 8 carbon atoms, such as hexafluoropropylene (HFP) and / or perfluoro(alkyl vinyl ether) (PAVE), wherein the straight-chain or branched alkyl groups contain 1 to 5 carbon atoms. Preferred PAVE monomers are those wherein the alkyl groups contain 1, 2, 3, or 4 carbon atoms, and copolymers can be prepared using several PAVE monomers. Preferred TFE copolymers include FEP (TFE / HFP copolymer), PFA (TFE / PAVE copolymer), TFE / HFP / PAVE (where PAVE is PMVE, PEVE and / or PPVE), MFA (TFE / PMVE / PAVE, where the alkyl group of PAVE has at least two carbon atoms) and THV (TFE / HFP / VF2).

[0076] The aforementioned melt-processable fluoropolymers can be characterized by MFR as described above for melt-processable TFE copolymers such as PFA and FEP, i.e., by the procedure of ASTM 1238, using standard conditions for the specific polymer, including a 5 kg weight on the molten polymer in a plasticizer.

[0077] Other useful polymers are film-forming polymers of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride copolymers, as well as polyvinyl fluoride (PVF) and vinyl fluoride copolymers.

[0078] This invention can also be used to prepare fluorocarbon elastomers (fluorinated elastomers). Fluorinated elastomers typically have a glass transition temperature below 25°C and exhibit little or no crystallinity at room temperature and little or no crystallinity at melting temperature. Fluorinated elastomers prepared by the method of this invention are typically copolymers containing 25% to 75% by weight of a first fluorinated monomer, which may be vinylidene fluoride (VF2) or tetrafluoroethylene (TFE), based on the total weight of the fluorinated elastomer. The remaining units in the fluorinated elastomer consist of one or more additional comonomers different from the first monomer, selected from fluorinated monomers, hydrocarbon olefins, and mixtures thereof. The fluorinated elastomer may also optionally contain units of one or more curing site monomers. When present, the content of the copolymerized curing site monomer is typically 0.05% to 7% by weight based on the total weight of the fluorocarbon elastomer. Examples of suitable monomers for curing sites include: i) fluorinated olefins or fluorinated vinyl ethers containing bromine, iodine, or chlorine; ii) fluorinated olefins or fluorinated vinyl ethers containing nitrile groups; iii) perfluorinated (2-phenoxypropyl vinyl ether); and iv) non-conjugated dienes. The method of the present invention can also be used with iodine- or bromine-containing chain transfer agents such as diiodoperfluoroalkane compound I (CF2). n Fluorinated elastomers polymerized in the presence of I (where n is 3 to 7), the chain transfer agent providing curing sites to the terminal carbon of the fluorinated elastomer.

[0079] Preferred TFE-based fluoroelastomer copolymers include TFE / PMVE, TFE / PMVE / E, TFE / P, and TFE / P / VF2. Preferred VF2-based fluorocarbon elastomer copolymers include VF2 / HFP, VF2 / HFP / TFE, and VF2 / PMVE / TFE. Any of these elastomer copolymers may further include curing site monomer units and curing sites formed using iodine- or bromine-containing chain transfer agents.

[0080] Hydrocarbon dispersant

[0081] The polymerization method according to the present invention employs a hydrocarbon dispersant comprising a compound of formula I:

[0082] R-(XZ) n I

[0083] Wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups, the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in one or more aliphatic groups is at least about 70%, and the hydrophobic moiety does not contain siloxane units.

[0084] Each X can be the same or different and represents the hydrophilic part of the ion;

[0085] Each Z can be the same or different and represents one or more counterions of the hydrophilic portion of the ion; and

[0086] Where n is between 1 and 3.

[0087] The dispersant used in the polymerization method according to the invention exhibits low reactivity with the fluoropolymer radicals that grow in the polymerization initiator and / or in the emulsion polymerization of fluoropolymers.

[0088] In the hydrocarbon dispersant used in the method of the present invention, the percentage of total CH3 groups relative to the total number of CH3, CH2, and CH groups in one or more aliphatic groups in the hydrophobic hydrocarbon moiety is at least about 70%. Preferably, the percentage of total CH3 groups relative to the total number of CH3, CH2, and CH groups in one or more aliphatic groups in the hydrophobic hydrocarbon moiety is at least about 75%, more preferably at least about 80%, more preferably at least about 85%, more preferably at least about 90%, more preferably at least about 95%, and most preferably 100%.

[0089] While not wishing to be bound by any operational theory, it is believed that hydrocarbon dispersants having the aforementioned percentage of total CH3 groups relative to the total number of CH3, CH2, and CH groups in one or more aliphatic groups in the hydrophobic hydrocarbon moiety impart resistance to free radical attack from initiators and / or growing fluoropolymer free radicals used in polymerization. Surfactants having long-chain hydrocarbon or polyoxyalkylene moieties are susceptible to such free radical attack. Preferably, in the method of the present invention, the hydrophobic hydrocarbon moiety in the hydrocarbon dispersant contains no more than 3 consecutive CH2 groups, more preferably no more than 2 consecutive CH2 groups, and most preferably no consecutive CH2 groups. Preferably, in the method of the present invention, the hydrophobic hydrocarbon moiety in the hydrocarbon dispersant contains at least 3 CH3 groups, more preferably at least 4 CH3 groups. A preferred range for the number of CH3 groups in the hydrophobic hydrocarbon moiety is 3 to 12. Another preferred range for the number of CH3 groups in the hydrophobic hydrocarbon moiety is 3 to 10. Another preferred range for the number of CH3 groups in the hydrophobic hydrocarbon moiety is 3 to 7. Another preferred range for the number of CH3 groups in the hydrophobic hydrocarbon moiety is 4 to 7.

[0090] In another preferred embodiment of the method of the present invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant does not contain carbon-hydrogen bonds, which have a bond dissociation energy of less than about 100 kcal / mol to generate hydrocarbon free radicals.

[0091] The hydrocarbon dispersants used according to the invention do not contain siloxane units. While not wishing to be bound by any operational theory, it is believed that a high percentage of CH3 groups relative to the total number of CH3, CH2, and CH groups present in some siloxane surfactants does not confer the same level of resistance to radical attacks by the hydrophobic hydrocarbon moiety against the initiator and / or the growing fluoropolymer radicals used for polymerization, as is achieved using the hydrocarbon dispersants according to the invention with the aforementioned percentage of total CH3 groups relative to the total number of CH3, CH2, and CH groups. Furthermore, siloxane surfactants are prone to hydrolysis and redistribution side reactions under typical emulsion polymerization conditions.

[0092] The low reactivity of the hydrocarbon dispersants used in the methods of the present invention can be demonstrated by their performance in tests in which the hydrocarbon dispersants are exposed to an oxidant. In a preferred embodiment of the invention, in the test method described and illustrated in Reactivity Example 1, the hydrocarbon dispersant has a loss of less than about 10% by weight of tert-butyl peroxide. More preferably, the hydrocarbon dispersant has a loss of less than about 5% by weight of tert-butyl peroxide.

[0093] The term "hydrocarbon" in relation to the hydrophobic hydrocarbon moiety means that at least 85% of the monovalent substituents on the carbon atom are hydrogen, and substitution by halogens such as fluorine or chlorine is possible, provided that the low reactivity of the dispersant is not adversely affected during polymerization. In preferred hydrophobic hydrocarbon moieties, at least about 90%, more preferably at least about 95%, of the monovalent substituents are hydrogen. In the most preferred embodiment, 100% of the monovalent substituents on the carbon atom are hydrogen. Therefore, in a preferred embodiment of the invention, the hydrophobic hydrocarbon moiety is halogen-free. The term "hydrocarbon" in relation to the hydrocarbon dispersant is intended to have the same meaning as described above for the hydrophobic hydrocarbon moiety.

[0094] In another preferred embodiment, one or more aliphatic groups in the hydrophobic hydrocarbon moiety are acyclic or cyclic alkyl groups, most preferably acyclic, wherein the percentage of total CH3 groups relative to the total number of CH3, CH2, and CH groups in one or more aliphatic groups in the hydrophobic hydrocarbon moiety is at least about 70%. Preferred acyclic alkyl groups are tert-butyl and 2,3,3-trimethyl-2-butyl groups that do not contain CH2 or CH groups.

[0095] The hydrophobic hydrocarbon moiety may contain heteroatom-containing divalent or trivalent linking groups that do not significantly increase the reactivity of the dispersant during polymerization. Examples of suitable heteroatom-containing divalent or trivalent linking groups are ethers, esters, sulfides, sulfones, sulfoxides, sulfonamides, carbonates, carbonyl groups, phosphonates, and phosphate esters. The heteroatom-containing divalent or trivalent linking groups may be present within one or more saturated or unsaturated, acyclic or cyclic aliphatic groups or in other positions within the hydrophobic hydrocarbon moiety. For example, in one embodiment of the invention, the heteroatom-containing divalent or trivalent linking group may be present within one or more saturated or unsaturated, acyclic or cyclic aliphatic groups. In another embodiment of the invention, where the hydrophobic hydrocarbon group contains an aromatic group, the divalent or trivalent linking group may connect one or more saturated or unsaturated, acyclic or cyclic aliphatic groups to an aromatic group, such as an ether bond, such that the aliphatic group is an alkoxy group. In another embodiment of the invention, where multiple aromatic groups are present, the heteroatom-containing divalent or trivalent linking group may link the aromatic groups together. The hydrocarbon dispersant used in the method of the present invention may have divalent or trivalent linking groups containing heteroatoms at multiple positions in the hydrophobic hydrocarbon portion.

[0096] The ionic hydrophilic moiety X can be an anion or a cation. Preferably, the ionic hydrophilic moiety X is selected from the group consisting of: acid groups and their salts, quaternary ammonium groups, amine oxide groups, and tetrazolium groups. One or more counterions Z of the hydrophobic moiety, having an opposite charge to the ionic hydrophilic moiety, will be present in a molar amount balancing the charge of the ionic hydrophilic moiety. The counterions are preferably hydrocarbon dispersants that provide sufficient solubility in the aqueous medium under the conditions used in this method. Preferably, the ionic hydrophilic moiety X is anionic. In a preferred embodiment, the hydrophilic moiety and the counterion XY are of formula -A. - -Y + The group, wherein A - It is a carboxylate, sulfonate, sulfate, phosphonate, or phosphate group, and Y is therein. + It is hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal, or alkaline earth metal. Most preferably, A... - It is a sulfonate group. Up to three ionic hydrophilic moieties may exist, although only one such moiety can impart sufficient hydrophilic properties to the hydrocarbon dispersant to function effectively in this method.

[0097] The ionic hydrophilic moiety can bond to the hydrophobic hydrocarbon moiety at any position in the emulsion polymerization of fluoropolymers, enabling the compound to be used effectively as a dispersant.

[0098] In one embodiment of the method of the present invention, the hydrophobic hydrocarbon portion is "fully aliphatic". "Fully aliphatic" means that the hydrophobic hydrocarbon portion contains no aromatic groups and only one or more saturated or unsaturated, acyclic or cyclic aliphatic groups, wherein the percentage of total CH3 groups relative to the total number of CH3, CH2, and CH groups in the one or more aliphatic groups is at least about 70%. The hydrophobic hydrocarbon portion may contain only one aliphatic group or may contain multiple aliphatic groups linked by linking groups (such as those described above). In embodiments of the present invention in which the hydrophobic hydrocarbon portion of the hydrocarbon dispersant is entirely aliphatic, the hydrocarbon dispersant has a molecular weight of at least about 170 g / mol, preferably at least about 180 g / mol, more preferably at least about 190 g / mol, and even more preferably at least about 200 g / mol, without the counterion Z. The preferred upper limit of the molecular weight of any of the lower limits of this embodiment of the present invention without the counterion Z is no more than about 750 g / mol.

[0099] In another embodiment of the method of the present invention, the hydrophobic hydrocarbon portion comprises one or more aromatic groups. One or more saturated or unsaturated, acyclic or cyclic aliphatic groups may be directly bonded to the aromatic groups or bonded via linking groups such as those described above. If multiple aromatic groups are present, they may be directly linked together, linked by linking groups such as those described above, or linked together via aliphatic groups. In embodiments of the present invention in which the hydrophobic hydrocarbon portion of the hydrocarbon dispersant contains at least one aromatic group, the hydrocarbon dispersant has a molecular weight of at least about 215 g / mol, preferably 220 g / mol, more preferably at least about 225 g / mol, and even more preferably at least about 230 g / mol when the counterion Z is absent. The preferred upper limit of the molecular weight of any of the lower limits of this embodiment of the present invention, when the counterion Z is absent, is no more than about 800 g / mol.

[0100] In embodiments of the invention having one or more aromatic groups, the aromatic group is typically a phenyl group, but may also be a polycyclic or heterocyclic aromatic group.

[0101] In embodiments of the invention comprising one or more aromatic groups, the one or more aromatic groups have a Hammett σ+ value greater than about -1.0, more preferably greater than about -0.8, and most preferably greater than about 0. The Hammett σ+ value of the aromatic ring is calculated by summing the Hammett σ+ values ​​of each substituent on the ring. Hydrogen has a value of zero. The Hammett σ+ values ​​are listed in the table in Hansch et al., Chemical Reviews, 1991, Vol. 91, pp. 165-195. The Hammett σ+ value can also be determined by the method reviewed by Hansch et al.

[0102] In a preferred embodiment of the method of the present invention, the hydrocarbon dispersant comprises a substitution portion of the following formula:

[0103]

[0104] Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0105] In embodiments comprising one or more aromatic groups, the hydrophobic hydrocarbon moiety preferably does not contain methyl groups directly bonded to the aromatic groups. It is also preferred in such embodiments that the hydrophobic hydrocarbon moiety does not contain benzyl hydrogen atoms. It is further preferred in such embodiments that the hydrophobic hydrocarbon moiety does not contain phenolic hydroxyl groups. While it is not desirable to be bound by any operational theory, dispersants having such groups or structures are believed to be susceptible to radical attack from initiators used in polymerization and / or from the growing free radicals of fluoropolymers.

[0106] The hydrophobic moiety of a hydrocarbon may include any of a variety of substituents, provided that such groups do not significantly and adversely affect the low reactivity of the hydrocarbon dispersant or impair its effectiveness as a dispersant.

[0107] In a preferred embodiment of the method of the present invention, the hydrophobic hydrocarbon portion of the hydrocarbon dispersant contains 8 to 50 carbon atoms, preferably 10 to 40 carbon atoms, more preferably 12 to 30 carbon atoms, and most preferably 12 to 25 carbon atoms.

[0108] Table A in the following examples lists various embodiments of hydrocarbon dispersants suitable for the methods according to the invention. The invention is not intended to be limited to the disclosed embodiments, and many other dispersants within the scope of the claims as described above can be used in the methods according to the invention. Table A also includes various comparative dispersants that can be compared with low-reactivity dispersants in polymerization methods for preparing fluoropolymers.

[0109] In a preferred embodiment of the method of the present invention, the hydrocarbon dispersant is a compound of formula II:

[0110]

[0111] Where R 2′ and R 2″ They are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to R 2′ and R 2″ The percentage of the total number of CH3, CH2, and CH groups in the group is at least about 70%, or R 2′ and R 2″They can be joined together to form a saturated or unsaturated aliphatic ring that can contain ether or ester bonds, provided that the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in the ring is at least about 70%.

[0112] Where R 1 It is hydrogen, methoxy, ethoxy, or phenoxy; and

[0113] Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0114] Preferably, in the compound of formula II, R 2′ and R 2″ It is the same or different and is tert-butyl-, tert-butoxy, 2,3,3-trimethyl-2-butyl or 2,3,3-trimethyl-2-butoxy or -CO(O)C(CH3)3, and wherein R 1 It is hydrogen or methoxy, and where Y is hydrogen or methoxy. + It is hydrogen, ammonium, or an alkali metal.

[0115] In another preferred embodiment, in the compound of formula II, R 2′ and R 2″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 1 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0116] In another preferred embodiment, in the compound of formula II, R 2′ and R 2″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 1 It is methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

[0117] In another preferred embodiment, in the compound of formula II, R 2′ and R 2″ All are tert-butyl, R 1 It is hydrogen or methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

[0118] Preferred examples of compounds of Formula II are shown below, and their use in the method according to the invention is illustrated in the examples:

[0119]

[0120] Y in these preferred dispersants + It can be hydrogen, ammonium, or alkali metal.

[0121] In a preferred embodiment of the method of the present invention, the hydrocarbon dispersant is a compound of formula III:

[0122]

[0123] Where R 3 R 4′ and R 4″ They are the same or different and are hydrogen or saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 3 R 4′ and R 4″ The percentage of the total number of CH3, CH2, and CH groups in the group is at least about 70%, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and

[0124] Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0125] Preferably, in compounds of formula III, R 3 R 4′ and R 4″ They are the same or different and are hydrogen, tert-butyl, tert-butoxy, 2,3,3-trimethyl-2-butyl, or 2,3,3-trimethyl-2-butoxy, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0126] In a preferred embodiment, in the compound of formula III, R 3 It is tert-butyl or 2,3,3-trimethyl-2-butyl, R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0127] In another preferred embodiment, in the compound of formula III, R 3 It is tert-butyl, and R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0128] In another preferred embodiment, in the compound of formula III, R 4′ and R 4″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 3 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0129] In another preferred embodiment, in the compound of formula III, R 4′ and R 4″ For tert-butyl, R 3 It is hydrogen, and Y + It consists of hydrogen, ammonium, and alkali metals.

[0130] Preferred examples of compounds of formula III are shown below, and their use in the method according to the invention is illustrated in the examples:

[0131]

[0132] Y in these dispersants + It can be hydrogen, ammonium, or alkali metal.

[0133] According to another aspect of the invention, the aqueous composition comprises a hydrocarbon dispersant of formula II:

[0134]

[0135] Where R 2′ and R 2″ They are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to R 2 and R 3 The percentage of the total number of CH3, CH2 and CH groups in the group is at least about 70%, or they can be joined together to form a saturated or unsaturated aliphatic ring that can contain ether bonds or ester bonds, provided that the percentage of the total number of CH3 groups relative to the total number of CH3, CH2 and CH groups in the ring is at least about 70%.

[0136] Where R 1 It is hydrogen, methoxy, ethoxy, or phenoxy; and

[0137] Where Y +It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0138] Preferably, in the aqueous composition of the compound of formula II, R 2′ and R 2″ They are the same or different and are tert-butyl-, tert-butoxy, 2,3,3-trimethyl-2-butyl, 2,3,3-trimethyl-2-butoxy, or -CO(O)C(CH3)3, and wherein R 1 It is hydrogen, methoxy, or phenoxy, and wherein Y is hydrogen, methoxy, or phenoxy. + It is a cation selected from the group consisting of hydrogen, ammonium, or alkali metals.

[0139] Preferably, in the aqueous composition of the compound of formula II, R 2′ and R 2″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 1 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0140] In a preferred embodiment, in the compound of formula II, R 2′ and R 2″ They are the same or different and are tert-butyl- or 2,3,3-trimethyl-2-butyl, and R 1 It is a methoxy group.

[0141] In a preferred embodiment, in the compound of formula II, R 2′ and R 2″ All are tert-butyl, R 1 It is hydrogen or methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

[0142] Preferred examples of compounds of formula II used in aqueous compositions are described above in the description of methods employing dispersants of formula II.

[0143] Aqueous compositions of the compounds of Formula II can be used in a variety of applications, but are particularly useful as aqueous media for the polymerization of fluorinated monomers to form aqueous dispersions of fluorinated polymer particles, as in the method according to the invention.

[0144] The present invention also provides a compound of formula III:

[0145]

[0146] Where R 3 R 4′ and R 4″They are the same or different and are hydrogen or saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 3 R 4′ and R 4″ The percentage of the total number of CH3, CH2, and CH groups in the group is at least about 70%, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and

[0147] Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0148] This invention provides preferred compounds, wherein R 3 R 4′ and R 4″ They are the same or different and are hydrogen, tert-butyl, tert-butoxy, 2,3,3-trimethyl-2-butyl, or 2,3,3-trimethyl-2-butoxy, provided that R 3 R 4′ and R 4″ At least one of them is not hydrogen, and when R 4′ and R 4″ When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4′ and R 4″ Not hydrogen, and Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

[0149] In a preferred embodiment, R 3 It is tert-butyl or 2,3,3-trimethyl-2-butyl, R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0150] In another preferred embodiment, R 3 For tert-butyl, R 4′ and R 4″ It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

[0151] In another preferred embodiment, R 4′ and R4″ Are they the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 3 It is hydrogen, and Y + It consists of hydrogen, ammonium, and alkali metals.

[0152] In another preferred embodiment, R 4′ and R 4″ For tert-butyl, R 3 It is hydrogen, and Y + It consists of hydrogen, ammonium, and alkali metals.

[0153] Preferred examples of compounds of formula III are described above in the description of the method using dispersants of formula III.

[0154] Preparation of hydrocarbon dispersants

[0155] Some embodiments of the hydrocarbon dispersant used in carrying out the present invention are known compounds. For example, among the compounds described in Table A, the following are known compounds: I-1,3,5-bis(1,1-dimethylethyl)-4-methoxybenzenesulfonic acid, I-5,2-(4-(tert-butyl)phenoxy)-2-methylpropionic acid; I-8,3,5-di-tert-butylbenzenesulfonic acid; I-9,4-(1,1,3,3-tetramethylbutyl)benzenesulfonic acid; I-10,N-[[4-(1,1-dimethylethyl)phenyl]sulfonyl]-2-methylalanine; and I-14,2,2,3,3,4,4-hexamethylglutaric acid.

[0156] In addition, some of the dispersants compared in Table A are known compounds: sodium C-4,4-tert-butylbenzenesulfonate; sodium C-8,4-(phenylsulfonyl)benzenesulfonate; sodium C-9,3-(diphenylphosphoyl)benzenesulfonate; sodium C-10,2-hydroxy-2,4,4-trimethylpentane-1-sulfonate; sodium C-11,3,5-diisopropylbenzenesulfonic acid; and sodium C-12,3,5-ditert-butyl-4-hydroxybenzenesulfonic acid.

[0157] Many embodiments of the hydrocarbon dispersants used according to the present invention are novel material compositions or are not commercially available. These novel or non-commercial dispersants can be prepared by applying synthetic transformations of appropriately selected commercially available or synthetic precursors. The synthetic transformations associated with the production of various novel or non-commercial hydrocarbon dispersants are described below. The synthesis of specific embodiments of the novel hydrocarbon dispersants and certain comparative dispersants listed in Table A is illustrated in the following synthetic examples.

[0158] Preparation method: Aromatic sulfonation

[0159] In one embodiment, the hydrocarbon dispersant has an aromatic sulfonic acid group and can be prepared by a method comprising the step of reacting a suitable precursor aromatic compound with chlorosulfonic acid. This method can be carried out in a solvent in which the precursor and chlorosulfonic acid have solubility. Examples of such solvents include chloroalkanes, such as dichloromethane. The method can be carried out at low temperatures, such as -10°C, during mixing of the precursor and chlorosulfonic acid. The resulting reaction mixture can then be stirred at ambient temperature, for example, for 2 to 18 hours until the reaction is complete. The method can be carried out at ambient pressure, and the product can be separated and purified by recrystallization, precipitation, or other techniques known in the art. (Sulfonic acids have excessively low vapor pressures for distillation.)

[0160] Examples of hydrocarbon dispersants prepared using this method include synthetic examples of C-4, C-8, C-11, C-12, I-1, I-3, I-7, I-9, I-8, I-11, I-12 and I-13.

[0161] Preparation method: Electrophilic aromatic alkylation

[0162] In one embodiment, the hydrocarbon dispersant has a hydrophobic hydrocarbon moiety, which can be prepared by a method comprising reacting a suitable aromatic compound with a suitable haloalkane in the presence of a Lewis acid catalyst. This method is typically carried out in a solvent in which the aromatic compound and the haloalkane have solubility. Examples of such solvents include aromatic hydrocarbons such as chlorobenzene. The method can be carried out at low temperatures, such as -20°C, during the contact of the aromatic compound and the haloalkane in the presence of a Lewis acid. After all the reaction components are added, the resulting reaction mixture is then typically stirred at low temperature, for example, for 10 minutes, until the reaction is complete. The method is typically carried out at ambient pressure, and the product is separated by washing with water and then purified by vacuum distillation.

[0163] An example of a novel hydrocarbon dispersant prepared using this method is the synthesis example of I-4.

[0164] Preparation method: Ketone conversion

[0165] It is an alcohol, and then the alcohol is converted into a halogen.

[0166] In one embodiment, the hydrocarbon dispersant has a hydrophobic hydrocarbon moiety, wherein the hydrophobic hydrocarbon moiety can be prepared by a two-step method comprising step (i) reacting a suitable ketone with a nucleophilic alkylating agent to prepare an alcohol, followed by step (ii) replacing the resulting alcohol with a halide to obtain a haloalkane.

[0167] Step (i) can be carried out using a conventional Grignard reaction method, in which an alkyl magnesium halide Grignard reagent is reacted with a ketone to give an alcohol. This step can be carried out in a solvent used to prepare the Grignard reagent, and the ketone has solubility. Examples of such solvents include hydrocarbon ethers, such as diethyl ether. The method can be carried out at low temperatures, such as -20°C, during the contact of the Grignard reagent and the ketone. After all the reaction components are added, the resulting reaction mixture is then typically stirred at low temperatures, for example, for 30 minutes, until the reaction is complete. The method is typically carried out at ambient pressure, and the product alcohol is separated by washing with water and then purified by vacuum distillation.

[0168] Step (ii) can be carried out by reacting the product alcohol with a hydrohalic acid (preferably HCl) to obtain a haloalkane. This step can be carried out in water, wherein the alcohol optionally has suitable solubility, together with a co-solvent. The method can be carried out at room temperature. After the alcohol is added to HCl, the resulting reaction mixture is then typically stirred at ambient temperature for, for example, 30 minutes until the reaction is complete. The method is typically carried out under ambient pressure, and the product haloalkane is separated by washing with water and then purification (e.g., by vacuum distillation or recrystallization, if appropriate).

[0169] Steps (i) and (ii) above result in the formation of haloalkanes, which can be used to produce hydrophobic hydrocarbon moieties via the electrophilic aromatic alkylation method described earlier herein.

[0170] An example of a novel hydrocarbon dispersant prepared using this method is the synthesis example of I-4.

[0171] Preparation method: Oxidation of sulfide or phosphine moiety

[0172] In one embodiment, the hydrocarbon dispersant has a sulfonyl moiety and can be prepared by a method comprising the step of reacting a suitable sulfide compound with a suitable oxidant such as hydrogen peroxide. This method can be carried out in a solvent in which the aromatic sulfide has solubility. Examples of such solvents include water. In some cases, the method can be carried out at ambient temperature to about 95°C during the contact between the sulfide and the oxidant. After all the reaction components are combined, the resulting reaction mixture is then typically stirred at ambient temperature for, for example, 60 minutes until the reaction is complete. The method is typically carried out at ambient pressure, and the product is separated and purified (e.g., by vacuum distillation or recrystallization, if appropriate).

[0173] Examples of novel hydrocarbon dispersants with sulfonyl moieties prepared using this method include synthetic examples of C-8, I-3, and I-13.

[0174] In one embodiment, the hydrocarbon dispersant has a sulfinyl group, which can be prepared by a method including the step of reacting a suitable sulfide compound with a suitable oxidant such as hydrogen peroxide. The method for preparing the sulfinyl-based hydrocarbon dispersant can be substantially the same as that for preparing the sulfonyl-based dispersant, except that the sulfonyl-based dispersant will require a relatively larger amount of oxidant than the sulfonyl-based dispersant. For example, the sulfonyl-based dispersant requires at least about 2 equivalents of oxidant per metric amount of sulfide compound, while the sulfinyl-based dispersant requires about 1 equivalent or less of oxidant per metric amount of sulfide compound.

[0175] Examples of novel hydrocarbon dispersants with sulfinyl moieties prepared using this method include the synthetic examples of I-11 and I-12.

[0176] In one embodiment, the hydrocarbon dispersant has a phosphoryl group, which can be prepared by a method including the step of reacting a suitable phosphine compound with a suitable oxidant such as hydrogen peroxide. The method for preparing the phosphoryl group embodiment of the hydrocarbon dispersant can be substantially the same as the method for preparing the sulfonyl group embodiment, except that the phosphoryl group embodiment requires only about one equivalent or less of the oxidant per equimolar amount of phosphine compound.

[0177] An example of a novel hydrocarbon dispersant with a phosphoryl group prepared using this method is the synthesis example of C-9.

[0178] Preparation method :

[0179] Nucleophilic substitution of halides by aromatic sulfides or phenolates

[0180] In some embodiments, the preparation of the hydrocarbon dispersant involves method (i) of forming a sulfur-carbon bond, thereby resulting in the formation of an alkylphenyl sulfide, or method (ii) of forming an oxygen-carbon bond, thereby resulting in the formation of an alkylphenyl sulfide. In these embodiments, methods (i) and (ii) involve nucleophilic substitution of a halogen from an alkyl halide via (i) a phenyl sulfide or (ii) a phenolic salt, respectively.

[0181] Method (i) can be carried out by reacting a suitable thiophene salt with a suitable alkyl halide. This method can be carried out in water as a solvent in the presence of a phase-transfer catalyst such as a phosphonium alkyl halide. The method can be carried out at an elevated temperature such as 70°C for a suitable time period, such as 4 hours. This method is typically carried out under ambient pressure, and the product alkylphenyl sulfide is separated by extraction into an organic solvent, washing with water, drying, and purification (e.g., by vacuum distillation or recrystallization, if appropriate).

[0182] Examples of novel hydrocarbon dispersants prepared using this method include the synthetic examples of I-13 and I-12.

[0183] Method (ii) can be carried out by reacting a suitable phenolate with a suitable alkyl halide. This method can be carried out in a polar aprotic solvent such as ethanol or ethyl acetate, or a mixture thereof. The method can be carried out at an elevated temperature (e.g., by reflux of ethyl acetate / ethanol) for an appropriate period of time, such as 3 hours. The method is typically carried out at ambient pressure, and the product alkylphenyl ether is separated by extraction into an organic solvent, washing with an aqueous brine solution, drying, and purification (e.g., by vacuum distillation or recrystallization, if appropriate).

[0184] An example of a novel hydrocarbon dispersant prepared using this method is the synthesis example of I-5.

[0185] Preparation method: epoxidation of olefins ,

[0186] Then, ring-opening of the epoxide is performed using bisulfite.

[0187] In one embodiment, the hydrocarbon dispersant can be prepared by a two-step method comprising step (i) reacting a suitable hydrophobic hydrocarbon-containing olefin with an epoxidizing agent to prepare an olefin epoxide, followed by step (ii) ring-opening the epoxide with a bisulfite to obtain a sulfonate-containing hydrocarbon dispersant.

[0188] Step (i) can be carried out by reacting a suitable hydrophobic hydrocarbon-containing olefin with a peroxycarboxylic acid such as m-chloroperbenzoic acid, resulting in the epoxidation of the olefin. This step can be carried out in a solvent such as an alkaline buffered aqueous solution or an organic solvent such as dichloromethane. The method can be carried out at ambient temperature and pressure. After all the reaction components are added, the resulting reaction mixture is then typically stirred, for example, for 2 days until the reaction is complete. The product epoxide can be separated from the reaction mixture by extraction into an organic solvent, followed by washing with water (in an embodiment where the reaction solvent is aqueous), drying, and purification (e.g., by vacuum distillation or recrystallization, if appropriate).

[0189] Step (ii) can be carried out by reacting the product epoxide with a sulfite to obtain a sulfonate-containing hydrocarbon dispersant. This step can be carried out under autogenous pressure at elevated temperatures (such as 145°C) in a pressure vessel with water as the solvent. After all the reactants are added, the resulting reaction mixture is then typically stirred at elevated temperatures and pressures, for example, for 6 hours until the reaction is complete. The product, the sulfonate-containing hydrocarbon dispersant, can be separated from the reaction mixture, typically by filtration, and then purified, for example by recrystallization from an alcohol such as ethanol.

[0190] An example of a novel hydrocarbon dispersant prepared using this method is the synthesis example of C-10.

[0191] Preparation method :

[0192] Aromatic sulfonyl chlorides are obtained through nucleophilic substitution of halides by amines.

[0193] In one embodiment, the hydrocarbon dispersant has a hydrophobic hydrocarbon-containing moiety, which can be prepared by a method comprising reacting a suitable aromatic sulfonyl chloride compound with a suitable amine. This method is typically carried out in a solvent in which the reaction components have solubility. Examples of such solvents include water containing a miscible polar aprotic cosolvent such as acetone. The method can be carried out at low temperatures, such as 0°C, during the mixing of the sulfonyl chloride and the amine. After all the reaction components have been added, the resulting reaction mixture is then typically stirred at ambient temperature, for example, for 18 hours until the reaction is complete. The method is typically carried out at ambient pressure, and the product is separated and purified by vacuum distillation. The product dispersant can be separated from the reaction mixture, typically by filtration, and then purified, for example, by recrystallization.

[0194] An example of a novel hydrocarbon dispersant prepared using this method is the synthesis example of I-10.

[0195] Preparation method: Reduction of phenol

[0196] In one embodiment, the hydrocarbon dispersant can be prepared by a two-step process comprising step (i) reducing a suitable hydrophobic hydrocarbon-containing phenol, followed by step (ii) aromatic sulfonation.

[0197] Step (i) can be carried out in two steps by reacting a suitable hydrophobic hydrocarbon-containing phenol: (i-1) reacting with sulfonyl fluoride in DMSO in the presence of triethylamine as a solvent, and then (i-2) reacting with formic acid in the presence of a catalyst of triethylamine, palladium(II) acetate, and 1,3-bis(diphenylphosphine)propane. Step (i-1) can be carried out at ambient temperature and autogenous pressure. After the addition of all reaction components, the resulting reaction mixture is then typically stirred, for example, for 6 hours until the reaction is complete. The resulting solution is bubbled with nitrogen, and then step (i-2) is carried out by adding triethylamine, palladium(II) acetate, and 1,3-bis(diphenylphosphine)propane to the reaction mixture. Formic acid is then added dropwise over several hours, such that the reaction temperature does not exceed 60°C by using a cold bath. The reduced phenol can be separated from the reaction mixture by extraction into an organic solvent, followed by washing with water, drying, and purification (e.g., by vacuum distillation or recrystallization, if appropriate).

[0198] The aromatic sulfonation of the reduced phenol from step (ii) can be carried out as described earlier herein. The hydrocarbon dispersant containing the sulfonate of the product can be separated from the sulfonation reaction mixture and then purified by vacuum distillation.

[0199] An example of a novel hydrocarbon dispersant prepared using this method is the synthesis example of I-9.

[0200] Preparation method: alkaline hydrolysis of esters

[0201] In one embodiment, the hydrocarbon dispersant has a carboxylic acid obtained by alkaline hydrolysis of an ester. The carboxylic acid group can be prepared from the ester by a method comprising the step of reacting a suitable precursor aromatic compound ester with a hydroxide. This method can be carried out in a solvent in which the precursor has solubility, such as a mixture of tetrahydrofuran and water. The method can be carried out at an elevated temperature, for example, 60°C, during mixing of the precursor and the hydroxide. The resulting reaction mixture can then be stirred at an elevated temperature (e.g., 60°C) and ambient pressure, for example, for 16 hours until the reaction is complete. The product carboxylic acid can be separated from the reaction mixture by extraction into an organic solvent, followed by washing with water, drying, and purification (e.g., by vacuum distillation or recrystallization, if appropriate).

[0202] An example of a novel hydrocarbon dispersant with a carboxylic acid moiety prepared using this ester hydrolysis method is the synthesis example of I-5.

[0203] Preparation method: Neutralize sulfonic acid with various alkalis

[0204] or carboxylic acid

[0205] In one embodiment, the hydrocarbon dispersant is a salt of a carboxylic acid or sulfonic acid, and the salt is prepared by an acid-base neutralization method. This method can be carried out in water, an organic solvent, or water containing a suitable polar organic co-solvent miscible with water (such as ethanol or tetrahydrofuran). A slurry or solution of the acid is prepared in the solvent, and then the acidic solution is neutralized to a pH of approximately 8 with a base containing the desired cation (such as an aqueous solution of sodium, potassium, or ammonia hydroxide). In one embodiment, the solvent is a polar aprotic, such as diethyl ether, and the neutralizing base is anhydrous ammonia. The product carboxylic acid salt or sulfonate can be separated from the reaction mixture, for example by filtration, and further purified as needed, for example by recrystallization.

[0206] Examples of novel hydrocarbon dispersants prepared using this neutralization method include synthetic examples of sodium, potassium, or ammonium salts of C-8, C-12, I-1, I-4, and I-8.

[0207] Aggregation methods

[0208] The method of the present invention can be carried out in a pressure polymerization reactor suitable for preparing aqueous dispersions of fluoropolymer particles by polymerization of fluorinated monomers. Typically, gaseous monomers such as TFE or VF2 are fed into the reactor to maintain the operating pressure, usually in the range of about 30 psig to about 1000 psig (0.3 MPa to 7.0 MPa). Depending on the fluoropolymer being produced, other or additional gaseous monomers may be fed into the reactor. Depending on the type of fluoropolymer being prepared, liquid monomers may be pre-loaded and / or pumped into the reactor.

[0209] Batch or continuous methods can be used, although batch methods are commonly used for the commercial production of perfluoropolymers. Continuous methods are known for some grades of fluorinated elastomers. In batch methods, the reactor is preferably equipped with a stirrer for an aqueous medium, and the aqueous medium is preferably stirred throughout the polymerization process. The reactor is also preferably equipped with a jacket surrounding the reactor, so that the reaction temperature can be conveniently controlled by circulating a temperature-controlled heat exchange medium.

[0210] The aqueous medium provided in the polymerization reactor is preferably deionized water and degassed water. The temperature of the reactor, and therefore the temperature of the aqueous medium, is preferably from about 25°C to about 120°C. To prepare PTFE homopolymers, paraffin wax is typically used as a stabilizer in the reactor, and the polymerization temperature used is usually higher than the melting point of the wax.

[0211] A polymerization initiator is added to an aqueous medium to polymerize the fluorinated monomer and form fluorinated polymer particles in the aqueous medium. This is suitably accomplished using an aqueous solution of the polymerization initiator, typically pumped into the reactor in a quantity sufficient to initiate the polymerization reaction, which is commonly referred to in the art as the “start-up” of the polymerization reaction. Start-up is typically determined by a decrease in reactor pressure from its initial pressurization, for example by a pressure drop of 10 psi (69 kPa), indicating the beginning of the consumption of the fluorinated monomer during polymerization and thus the start of the polymerization reaction. Start-up can also be determined in a method in which the reactor pressure is kept constant by increasing the feed rate of gaseous monomer into the reactor to maintain the pressure.

[0212] The polymerization initiator used is preferably a water-soluble free radical polymerization initiator. For TFE polymerization to produce PTFE, a preferred initiator is an organic peracid, such as bis(DSP) peroxide, requiring a large amount (e.g., at least about 600 ppm) to initiate the process. Optionally, reducing agents such as sodium formaldehyde sulfoxylate, fluoroalkyl sulfinates, metabisulfites, or ascorbic acid can be used with the organic peracid. Highly reactive initiators, such as inorganic persulfates like ammonium persulfate, can be used with smaller amounts of organic peracid. Organic peroxide initiators that are sufficiently soluble in aqueous media and readily generate alkoxy groups (such as alkyl hydroperoxides, e.g., tert-butyl hydroperoxide, optionally in combination with reducing agents such as sodium formaldehyde sulfoxylate, fluoroalkyl sulfinates, metabisulfites, or ascorbic acid) are advantageously used as initiators together with the hydrocarbon dispersants used in this invention, particularly for PTFE polymerization. For TFE copolymers such as FEP and PFA, and for fluorinated elastomers, inorganic persulfates such as ammonium persulfate can be used as initiators. Other initiators known in the art can also be used in the method according to the invention.

[0213] As is known in the art, when a polymerization reaction is underway, the added polymerization initiator can be supplemented by pumping an additional initiator solution into the reactor to initiate the reaction. For batches with higher solids content, it is preferable to add the supplementary initiator during polymerization.

[0214] For the preparation of modified PTFE and TFE copolymers, relatively deactivated fluorinated monomers such as hexafluoropropylene (HFP) may already be present in the reactor before pressurization with more active TFE fluorinated monomers. After startup, TFE is typically fed into the reactor to maintain the internal pressure at the operating pressure. If desired, additional comonomers such as HFP or perfluoro(alkyl vinyl ethers) may be pumped into the reactor. The aqueous medium should be thoroughly stirred to obtain the desired polymerization rate and comonomer incorporation (if present). For the preparation of fluorinated elastomers, a mixture of gaseous monomers in the proportions required to prepare the final fluorinated elastomer is typically fed into the reactor; for example, for VF2 / HFP dimers, VF2 and HFP are fed, or for VF2 / HFP / TFE terpolymers, VF2, HFP, and TFE are fed. For peroxide-curable fluorinated elastomers, it is preferable to add a curing site monomer, such as 4-iodo-3,3,4,4-tetrafluorobutene-1 (ITFB), to the batch later to introduce iodine or bromine curing sites into the fluorinated elastomer.

[0215] When molecular weight control is required, chain transfer agents can be introduced into the reactor, and they are sometimes used to prepare melt-processable fluoropolymers such as PFA. Preferred chain transfer agents include hydrogen, which may be cyclic aliphatic hydrocarbons, halogenated hydrocarbons, hydrohalogenated hydrocarbons, or alcohols having 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms. Representative preferred examples of such chain transfer agents are alkanes, such as ethane, chloroform, 1,4-diiodoperfluorobutane, and methanol. The amount and mode of addition of the chain transfer agent depend on the activity of the particular chain transfer agent and the desired molecular weight of the polymer product. Based on the weight of the resulting fluoropolymer, the amount of chain transfer agent supplied to the polymerization reactor is preferably from about 0.005% by weight to about 5% by weight, more preferably from about 0.01% by weight to about 2% by weight. For peroxide-curable fluoroelastomers, iodine- or bromine-containing chain transfer agents, such as the diiodoperfluoroalkyl compounds discussed above, can be used as chain transfer agents to provide iodine or bromine curing sites for bonding to the terminal carbons of the fluoroelastomer.

[0216] In a preferred embodiment of the method according to the invention, polymerization sites are provided in an aqueous medium. The polymerization sites in the aqueous medium increase the number of sites for fluoropolymer precipitation, resulting in smaller fluoropolymer particle size for a given percentage of solids. The hydrocarbon dispersants used according to the invention vary in their effectiveness of nucleation during polymerization. While not necessary for some hydrocarbon dispersants used according to the invention, providing polymerization sites is important for dispersants ineffective at nucleation, particularly for methods achieving high solids content with such dispersants. The performance of polymerization sites used in fluoropolymerization can be primarily judged by the smaller particle size of the fluoropolymer compared to polymerization reactions occurring without polymerization sites.

[0217] Polymerization sites can be provided in the aqueous medium before or simultaneously with the start of polymerization. Preferably, the polymerization sites are present before the start of polymerization. For polymerization sites formed by in-situ reaction and for lipophilic nucleation sites described below, it may be advantageous to form such polymerization sites simultaneously with the start of polymerization to shorten the interval time.

[0218] Providing polymerization sites in an aqueous medium is preferably achieved by adding nucleating additives to the aqueous medium. A variety of nucleating additives are available that can be used to provide polymerization sites.

[0219] One method for forming polymerization sites is to add a dispersion of small, non-ionomer fluoropolymer particles to an aqueous polymerization medium. These polymer particles, acting as nucleating additives, are commonly referred to as polymer seeds. As is known in the art, seeds can be formed by aqueous dispersion polymerization initiated by the free radicals of fluorinated monomers, which may include the use of suitable surfactants or dispersants to stabilize the fluoropolymer seeds in an aqueous medium. The polymer seeds may be the same as or different from the fluoropolymer prepared in this method, but they are generally the same as the polymer being prepared. Typically, the fluoropolymer dispersion used to provide the fluoropolymer seeds has a very small particle size, for example, from 1 nm to 50 nm, and is prepared by running the polymerization process to only low solids content when the particle size is only a fraction of that required for typical commercial use. In cases where a fluorinated surfactant is used as the stabilizing surfactant for preparing the polymer seeds, typically only a small amount of the fluorinated surfactant is needed to hold the polymer seeds in the dispersion.

[0220] A preferred method for providing polymerization sites for carrying out the method according to the invention is disclosed in U.S. Patent 8,153,738 (Leffew et al.), wherein polymerization sites are provided by adding dispersed particles of a fluorinated ionomer to an aqueous medium as a nucleating additive. Because the dispersed particles of the fluorinated ionomer contain a large number of ionic groups that are typically present along the polymer chain, the dispersed particles of the fluorinated ionomer are self-stabilizing as a dispersion in an aqueous medium and generally do not require surfactants. Preferably, the dispersed particles of the fluorinated ionomer are “highly fluorinated,” meaning that at least 90% of the monovalent atoms bonded to carbon atoms in the ionomer are fluorine atoms. Most preferably, the ionomer is perfluorinated. The ionic groups in the ionomer are also preferably sulfonic acid or sulfonate groups. Various types of fluorinated ionomers are suitable for preparing dispersed particles of fluorinated ionomers, such as those disclosed in U.S. Patents 3,282,875, 4,358,545, and 4,940,525.

[0221] Although other methods may be used, it is preferred that the dispersed particles of the fluorinated ionomer are formed by the method disclosed in U.S. Patent 6,150,426 (Curtin et al.). The method of U.S. Patent 6,150,426 can be used to form dispersed particles of the fluorinated ionomer in water, which are free of organic compounds that may interfere with polymerization. The dispersed particles in an aqueous medium formed by the method of U.S. Patent 6,150,426 can also be dried to form a powdery solid that can be easily redispersed in an aqueous medium. Furthermore, the dispersed particles of the fluorinated ionomer formed by this method have a very small particle size, for example, from about 2 nm to about 30 nm, and are very effective in generating a large number of polymerization sites when used as a nucleating additive.

[0222] In another preferred method of providing polymerization sites, a hydrocarbon-containing compound is used as a nucleating additive to form lipophilic nucleation sites that form in an aqueous medium, as disclosed in U.S. Patents 8,563,670 and 9,676,929 (Brothers et al.). These lipophilic nucleation sites are formed in situ and dispersed in the aqueous medium to provide polymerization sites. The lipophilic nucleation sites are formed by adding a small amount of a water-soluble hydrocarbon-containing compound and a degrading agent (preferably an oxidizing agent) to the aqueous medium before or during polymerization. Preferably, the amount of water-soluble hydrocarbon-containing compound added is no more than 50 ppm. The degrading agent causes the hydrocarbon-containing compound to undergo a reaction that degrades the compound, thereby enabling the water-soluble hydrocarbon-containing compound to form lipophilic nucleation sites.

[0223] In some embodiments, the water-soluble hydrocarbon-containing compound from which the lipophilic nucleation sites are derived is a hydrocarbon-containing surfactant as disclosed in U.S. Patent 8,563,670 (Brothers et al.). A variety of hydrocarbon-containing surfactants are suitable for forming lipophilic nucleation sites as disclosed in U.S. Patent 8,563,670. Preferably, nonionic hydrocarbon surfactants are used, such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, sorbitol alkyl esters, polyoxyethylene sorbitol alkyl esters, glycerides, and derivatives thereof. Preferred degradation of the surfactant results in the loss of its hydrophilicity and surfactant effects. However, it is not necessary for the surfactant to maintain the lipophilic nucleation sites of the dispersion as polymerization sites for the polymerization reaction.

[0224] In other embodiments, the water-soluble hydrocarbon compound used as a nucleating additive is a polyepoxide with a number-average molecular weight of about 50 to about 2000, as disclosed in U.S. Patent 9,676,929 (Brothers et al.). "Polyepoxide" means an oligomer or mixture of oligomers having oligomeric segments (such as polyethylene oxide, polyethylene oxide, polyethylene propylene oxide, and polyethylene butane). More than one type of segment may be present in the polyepoxide that can be used to carry out the invention. Preferably, a polyepoxide having only one type of segment is used. The polyepoxide may comprise oligomers with different molecular weights, and most commercially available materials are sold as mixtures of compounds having said average molecular weight, and thus comprise compounds with molecular weights distributed around the average value. If desired, a mixture of compounds with large molecular weight differences or completely different chemical compositions may be used by mixing different polyepoxides. The polyepoxide may be end-capped with any of a variety of end groups, and the end groups in a particular compound may be the same or different. The preferred epoxide nucleating additive is polypropylene glycol.

[0225] Preferably, the degradation of water-soluble hydrocarbon compounds is carried out by adding a degrading agent, preferably an oxidizing agent, to an aqueous medium. More preferably, the degrading agent is a free radical polymerization initiator.

[0226] Preferably, the formation of the dispersion of the lipophilic nucleation sites as described above is accompanied by an additional step of adding a water-soluble inorganic salt to the aqueous medium before the hydrocarbon compound is exposed to degradation. The water-soluble inorganic salt is preferably added to the aqueous medium before or during the exposure of the nucleating additive to the oxidant. The addition of the water-soluble inorganic salt can increase the number of fluoropolymer particles formed during nucleation. The preferred amount of the water-soluble inorganic salt is from about 0.01 ppm to about 80 ppm. Suitable water-soluble inorganic salts include, but are not limited to, sodium sulfite, sodium bisulfite, sodium chloride, potassium sulfite, potassium bisulfite, potassium carbonate, ammonium oxalate, sodium tetraborate, sodium acetate, ammonium carbonate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0227] Another preferred method for providing polymerization sites is to use fluoropolyether acid or salt nucleating additives of the type disclosed in U.S. Patent 7,897,682 (Brothers et al.) in a polymerizer combined with a hydrocarbon surfactant. Preferably, the fluoropolyether nucleating additive is a perfluoropolyether acid or a salt thereof. The acid group of the fluoropolyether acid or its salt is preferably selected from carboxylic acids, sulfonic acids, and phosphonic acids. In a preferred embodiment, the acid group of the fluoropolyether acid or its salt is a carboxylic acid. Preferably, the fluoropolyether acid is used in the form of an alkali metal salt or an ammonium salt, most preferably in the form of a sodium salt or an ammonium salt.

[0228] The preferred perfluoropolyether (PFPE) acid or its salt used according to the present invention can have any chain structure, wherein oxygen atoms in the molecular backbone are separated by saturated fluorocarbon groups having 1-3 carbon atoms. More than one type of fluorocarbon group may be present in the molecule. A representative structure has repeating units.

[0229] (-CFCF3-CF2-O-) n (I)

[0230] (-CF2-CF2-CF2-O-) n (II)

[0231] (-CF2-CF2-O-) n -(-CF2-O-) m (III)

[0232] (-CF2-CFCF3-O-) n -(-CF2-O-) m (IV)

[0233] These structures are discussed by Kasai in J. Appl. Polymer Sci. 57, 797 (1995). As disclosed therein, such PFPEs may have carboxylic acid groups or salts thereof at one or both ends. Similarly, such PFPEs may have sulfonic acid or phosphonic acid groups or salts thereof at one or both ends. Furthermore, PFPEs with acidic functional groups at both ends may have different groups at each end. For monofunctional PFPEs, the other end of the molecule is usually perfluorinated but may contain hydrogen or chlorine atoms. Generally, unless a single particular PFPE compound is prepared with particular care, PFPEs contain multiple compounds in varying proportions within a molecular weight range of approximately the average molecular weight.

[0234] Fluoroether acids or their salts have an average molecular weight that enables them to be used effectively as nucleating agents. The number-average molecular weight of the fluoroether acid or its salt is preferably greater than about 500 g / mol but less than about 6000 g / mol, because fluoroether acids or their salts with very high molecular weights are generally difficult to dissolve / disperse in aqueous polymerization media. It has been found advantageous to mix fluoroether acids or their salts with low-level or non-telomerizing dispersants, such as polar solvents, that do not significantly interfere with fluorination polymerization. A preferred class of dispersants includes C3 to C8 branched alcohols, with tert-butanol being a particularly suitable dispersant. Preferably, tert-butanol is used with the perfluoroether acid or its salt in a weight ratio of tert-butanol to perfluoroether acid of 1:2 to 2:1; more preferably, the amount of tert-butanol is less than the amount of perfluoroether acid.

[0235] U.S. Patent 9,732,212 discloses particularly preferred fluoropolyether acids or salts for use as nucleating additives to effectively disperse and provide effective nucleation. The fluoropolyether acid or salt is a mixture of fluoropolyether acids or salts having a number average molecular weight of about 800 g / mol to about 2500 g / mol. In the mixture, the amount of fluoropolyether acid or salt having a molecular weight of not more than about 500 g / mol does not exceed about 50 ppm by weight of the total amount of fluoropolyether acid or salt; the amount of fluoropolyether acid or salt having a molecular weight of about 2500 g / mol or greater does not exceed 40% by weight of the total amount of fluoropolyether acid or salt; and the amount of fluoropolyether acid or salt having a molecular weight of 3000 g / mol or greater does not exceed 10% by weight of the total amount of fluoropolyether acid or salt.

[0236] To carry out the polymerization method according to the invention, a hydrocarbon dispersant according to the invention is added to an aqueous medium such that the aqueous medium contains the hydrocarbon dispersant. The amount of hydrocarbon dispersant in the aqueous medium will vary depending on the type of dispersant, the fluoropolymer being prepared, and the desired solids content. A preferred range is from about 50 ppm to about 10,000 ppm based on the weight of the fluoropolymer solids, more preferably from about 100 ppm to about 5,000 ppm based on the weight of the fluoropolymer solids, even more preferably from about 1,000 ppm to about 5,000 ppm based on the weight of the fluoropolymer solids, and most preferably from 1,000 ppm to 4,000 ppm based on the weight of the fluoropolymer solids.

[0237] Because the hydrocarbon dispersant used according to the invention has low reactivity with the polymerization initiator and / or the grown fluoropolymer radicals, all hydrocarbon dispersants used for polymerization can be added before or simultaneously with the start of polymerization by pre-loading into the reactor. Alternatively, any of a variety of other methods can be used to provide the hydrocarbon dispersant in an aqueous medium. For example, as in the method disclosed in WO2012 / 064841A1, the addition of the hydrocarbon dispersant can be delayed until after the start of polymerization. Another method is to pre-load a portion of the hydrocarbon dispersant and then add one or more portions. As disclosed in WO2012 / 064841A1, the hydrocarbon dispersant can be continuously added to the aqueous medium throughout the batch or continuously after the start of polymerization. Continuous addition of the hydrocarbon dispersant to the batch can be combined with a portion of the hydrocarbon dispersant pre-loaded before or simultaneously with the start of polymerization. Combinations of these methods, as well as other methods, can be used as needed to add the hydrocarbon dispersant to the aqueous medium.

[0238] To achieve high solids batches and / or reduce downtime, particularly for the production of perfluoropolymers, the addition of the hydrocarbon dispersant can be delayed until after the start of polymerization, and the hydrocarbon dispersant can be added over time as polymerization proceeds. The hydrocarbon dispersant can be fed into the reactor continuously as polymerization proceeds, i.e., metered into the reactor. The technique disclosed in WO2012 / 064841A1 can be used for the delayed addition and continuous feeding of the hydrocarbon dispersant to carry out the method according to the invention.

[0239] If the hydrocarbon dispersant does not provide effective nucleation, especially for obtaining high solids, it is preferable to provide polymerization sites in an aqueous medium by one of the methods described above. In the method according to the invention, providing polymerization sites in combination with delayed addition of the hydrocarbon dispersant and continuous feeding of the hydrocarbon dispersant into the reactor may be advantageous.

[0240] After polymerization is complete, when the desired amount of dispersed fluoropolymer solids content is reached (usually several hours in batch processes), the feed is stopped, the reactor is vented, and the coarse dispersion of fluoropolymer particles in the reactor is transferred to a cooling or holding container.

[0241] The method of the present invention can prepare fluoropolymers with a wide range of solids contents, and the solids content of the polymerized aqueous fluoropolymer dispersion can range from about 10% by weight to a maximum of about 65% by weight. Preferably, the method prepares a polymer dispersion with a solids content of at least about 30% by weight, more preferably at least about 40%. The particle size (Dv(50)) of the fluoropolymer particles in the aqueous fluoropolymer dispersion can range from 10 nm to 500 nm, preferably Dv(50) is from about 100 nm to about 400 nm.

[0242] In the preferred method of the present invention, based on the total weight of the prepared fluoropolymer, polymerization produces less than about 10% by weight, more preferably less than 3% by weight, of undispersed fluoropolymer. Undispersed fluoropolymer (commonly referred to as agglomerates) refers to fluoropolymers that remain in the aqueous medium as undispersed fluoropolymer particles and are typically retained inside the reactor or present as large particles that settle or are filtered out from the dispersion. Undispersed polymers typically must be discarded as waste.

[0243] For use in fluoropolymer coatings on materials such as metals, glass, and fabrics, PTFE dispersions are typically transferred to a dispersion concentration operation, which produces a stable, concentrated dispersion suitable for use as a coating or for addition to coating formulations. Typically, the concentrated dispersion is stabilized with a nonionic surfactant and concentrated using known methods. The solids content of the concentrated dispersion is typically from about 35% by weight to about 70% by weight.

[0244] Certain grades of PTFE dispersions are prepared to produce fine powders. For this application known in the art, the dispersion is coagulated, the aqueous medium is removed, and the PTFE is dried to produce fine powders.

[0245] For melt-processable fluoropolymers such as FEP and PFA, the dispersion can be coagulated and dried using methods well known in the art, and then typically processed into convenient forms such as chips or granules for subsequent melt processing operations.

[0246] For fluorinated elastomers, the dispersion is also agglomerated. As is known in the art for the manufacture of fluorinated elastomer parts, the agglomerated fluorinated elastomer is typically formed into blocks, which are readily compounded with curing additives, fillers, pigments, etc., before being molded into parts and cured by heat.

[0247] Test methods

[0248] Rough Dispersion Size (RDPS)The measurement was performed using laser scattering with a Zetasizer Nano-ZS manufactured by Malvern Instruments. The sample for analysis was prepared in a 10×10×45mm polystyrene cuvette, capped, and placed in the analytical apparatus. Sample preparation was as follows: Deionized degassed water was drawn into a 10cc glass hypodermic syringe with a locking tip. The water used to rinse the cuvette and dilute the dispersion sample was substantially free of particles. A Whatman 0.02-micron filter (catalog number 6809-2002) was fitted to the locking tip of the syringe, and pressure was applied to force water through the filter and into the cuvette. Approximately 1.5 ml of water was placed in the cuvette, the cuvette was capped, shaken, and then the cap was opened. The water was poured out of the cuvette, ensuring that the cuvette was free of particles. Approximately 2.5 g of filtered water was placed in the cuvette. One drop of the fluoropolymer dispersion to be analyzed was added to the cuvette. The cuvette was capped and shaken to fully mix the fluoropolymer particles in the water. The sample was placed in a Nano-ZS to determine Dv(50). Dv(50) is the median particle size based on the volumetric particle size distribution, which is the particle size at which 50% of the population volume exists.

[0249] PTFE homopolymer Melting point (T) m ) The melting temperature was determined by differential scanning calorimetry (DSC). Unmelted PTFE homopolymer was heated from room temperature to 380°C at a heating rate of 2°C / min, and the reported melting temperature is the peak temperature of the endothermic reaction during the first melting.

[0250] In aqueous dispersions % by weight of fluoropolymer solids The following determination was performed using a moisture analyzer: The weight percentage (wt%) of fluoropolymer solids in the fluoropolymer dispersion was measured using an MB45 moisture analyzer manufactured by Ohaus. The measurement was performed as follows: A clean glass fiber mat was placed on the instrument balance and weighed. Two grams of the dispersion sample were pipetted onto the glass fiber mat. The drying process was started by pressing the start button. The integral halogen desiccator was programmed to reach 175°C. During the drying process, water will evaporate, and the result is displayed as weight percentage of solids upon completion. The typical drying time is approximately 5 minutes.

[0251] per cm 3 Number of particles per cm 3 The particle size (#) is calculated from the weight % of fluoropolymer solids using the following equation:

[0252]

[0253] Start-up time is considered to be the start of polymerization and is calculated as the time required for a 10 psi pressure drop from the maximum pressure observed during the injection of the initiator solution, or, if 10 psi is not reached, as the pressure drop observed after a set time. Start-up rate (psi / min)The voltage drop is calculated from the start-up time, which is 10 psi divided by the start-up time. If a start-up occurs, or if no start-up occurs, the observed voltage drop is divided by the set time.

[0254] The specific logarithmic viscosity of fluorinated elastomers was determined according to ASTM D5225-92 using a Viscotek Y501 viscometer sold by Malvern Panalytical Ltd.

[0255] Mooney viscosity was measured according to ASTM D1646 under conditions ML 1+10 (121°C). 。

[0256] The resistance to compressive permanent deformation is the percentage change after 70 hours at 200°C, as determined by the test protocol of ISO 815-1:2008.

[0257] Tensile strength and Elongation at break Determined according to ISO 37:2005C or 12008 test procedures.

[0258] Standard specific gravity (SSG) is measured according to ASTM D792-08.

[0259] The loss of tert-butyl peroxide (wt%) was determined by the test method described in Reactivity Example 1.

[0260]

[0261]

[0262]

[0263]

[0264]

[0265] Synthesis Examples

[0266] The following synthesis examples include examples of dispersants used in the method according to the invention and certain comparative dispersants that can be used for comparison in the following polymerization examples.

[0267] Synthesis Example 1

[0268] I-3(acid)-4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonic acid

[0269] 4-tert-butyldiphenyl sulfide (TCI) (815 g, 3.36 mol, 1 equivalent) was dissolved in DCM (dichloromethane, 1.6 L) under an inert atmosphere. The solution was cooled to -10 °C, and chlorosulfonic acid (422 g, 3.62 mol, 1.08 equivalent) was added dropwise. The reaction was stirred at ambient temperature for 18 hours. The solution was then bubbled with N2 for 30 minutes and transferred to a glass bottle.

[0270] Add water (1.75 L) to the reactor and heat it to 75°C. Attach a short-path distillation head and slowly add a portion of the bubbled DCM solution containing the sulfonic acid intermediate (4-(4-(tert-butyl)phenylthio)-benzenesulfonic acid) (2.5 kg solution, 750 g sulfonic acid intermediate, 2.33 mol) to control foaming during DCM distillation. After the DCM solution has been added, heat the reactor to 92°C for 15 minutes to ensure complete DCM removal. Remove the short-path distillation head and cool the reactor to ambient temperature.

[0271] A reflux condenser was attached to a feeding funnel containing 633 g (5.58 mol, 2.4 equivalents) of a 30 wt% H₂O₂ aqueous solution. The H₂O₂ solution was then slowly added, maintaining the reaction temperature between 25°C and 30°C. The reaction mixture was then stirred at ambient temperature until NMR analysis confirmed the completion of the reaction.

[0272] The reactor was then emptied into a large flask and refilled with platinum black (0.175 g, 0.9 mmol) and water (2 L). The suspension was heated to 75 °C. The reactor contents from the previous step were loaded into a feeding funnel and added slowly to control foaming. After the addition was complete, the heat was slowly increased to 92 °C, and the reaction was stirred until no peroxide was detected by the peroxide test strip. Additional water (4 L) was added, and the reaction was cooled to ambient temperature. The reaction mixture was filtered through a diatomaceous earth mat to give 9.7 kg of a clear product solution. Quantitative NMR analysis of the aliquots (DMSO internal standard, D2O solvent) showed that the solution contained 6.89 wt% of 4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonic acid (81% yield). 1H NMR (D2O, 400MHz): δ1.12 (s, 9H), 7.51 (d, 2H, J=8.5Hz), 7.74-7.92 (m, 6H).

[0273] Synthesis Example 2

[0274] I-11(acid)-4-((4-(tert-butyl)phenyl)sulfinyl)benzenesulfonic acid

[0275] 4-tert-butyldiphenyl sulfide (TCI) (815 g, 3.36 mol, 1 equivalent) was dissolved in DCM (1.6 L) under an inert atmosphere. The solution was cooled to -10 °C, and chlorosulfonic acid (422 g, 3.62 mol, 1.08 equivalent) was added dropwise. The reaction mixture was stirred at ambient temperature for 18 hours. The solution was then bubbled with N2 for 30 minutes and transferred to a glass bottle.

[0276] Water (2.25 L) was added to the reactor, and then heated to 75 °C. A short-path distillation head was attached, and a portion of the bubbled DCM solution containing sulfonic acid intermediate (4-(4-(tert-butyl)phenylthio)-benzenesulfonic acid) (2.5 kg solution, 750 g sulfonic acid intermediate, 2.33 mol) was slowly added to control foaming during DCM distillation. After the DCM solution addition was complete, the reactor was heated to 92 °C for 15 minutes to ensure complete DCM removal. The short-path distillation head was then removed, and the reactor was cooled to ambient temperature.

[0277] The reflux condenser was then attached to a feeding funnel containing 30% by weight H₂O₂ aqueous solution (317 g, 2.79 mol, 1.2 equivalents). The reactor and its contents were cooled to 15°C. The H₂O₂ solution was slowly added, maintaining the reaction temperature between 15°C and 20°C. The reaction mixture was then stirred at 25°C until NMR analysis confirmed the completion of the reaction.

[0278] The reactor was then emptied into a large flask and refilled with platinum black (0.1 g, 0.5 mmol) and water (2 L). The reactor contents from the previous step were loaded into a feeding funnel and added slowly at ambient temperature to control foaming. After the addition was complete, the reaction mixture was stirred at ambient temperature until no peroxide was detected by the peroxide test strip. Additional water (3 L) was added, and the reaction mixture was filtered through a diatomaceous earth mat to give 8.8 kg of a clear product solution. Quantitative NMR analysis of the aliquots (DMSO internal standard, D2O solvent) showed that the solution contained 6.95 wt% of 4-((4-(tert-butyl)phenyl)sulfinyl)benzenesulfonic acid (77% yield). ¹H NMR (D2O, 400 MHz): δ 0.99 (s, 9H), 7.30–7.75 (m, 8H).

[0279] Synthesis Example 3

[0280] I-13(acid)-4-(neopentylsulfonyl)benzenesulfonic acid

[0281] Neopentylphenyl sulfide was prepared according to the method employed in Org. Synth. 1978, 58, 143-146. Sodium thiophene (Sigma Aldrich) (47.8 g, 90% purity, 326 mmol, 1 equivalent) and tributylhexadecanylphosphonium bromide (Aldrich) (5.68 g, 11 mmol, 0.034 equivalent) were dissolved in water (102 mL). Neopentyl bromide (Beantown Chemical) (54.9 g, 98% purity, 356 mmol, 1.1 equivalent) was added, and the mixture was heated to 70 °C for 4 hours, then cooled to ambient temperature overnight. The layers were separated, and the aqueous layer was extracted with diethyl ether. The organic layers were combined and washed successively with water and then with brine. The organic layers were dried over magnesium sulfate, concentrated under reduced pressure, and vacuum distilled at 0.5 Torr and 55 °C to give 64 g of an oily substance (99% yield) of neopentylphenyl sulfide.

[0282] Neopentylphenyl sulfide (64 g, 355 mmol, 1 equivalent) was dissolved in DCM (dichloromethane, 240 mL) and cooled to -20 °C. Chlorosulfonic acid (43.4 g, 372 mmol, 1.05 equivalent) was added dropwise. After addition, the reaction mixture was stirred at -20 °C for 30 minutes, then heated to ambient temperature over 3 hours. Volatiles were removed under reduced pressure, and water (188 mL) was added to give 280 g of a 33 wt% aqueous solution of 4-(neopentylthio)benzenesulfonic acid (assuming quantitative yield).

[0283] A 33 wt% aqueous solution of 4-(neopentylthio)benzenesulfonic acid (50 g, 63.4 mmol, 1 equivalent) was diluted with water (100 mL) and cooled to 10 °C. A 30 wt% aqueous solution of H₂O₂ (36 g, 317 mmol, 5 equivalent) was slowly added over 1 hour, maintaining the temperature between 10 °C and 12 °C. The reaction mixture was then stirred at 10 °C for 5 days. Another H₂O₂ solution (36 g, 317 mmol, 5 equivalent) was added, and the reaction mixture was heated to 50 °C for 3 days, at which point NMR analysis showed complete conversion. Platinum black (50 mg, 0.25 mmol) was mixed with water (200 g), and the reaction mixture was added to a platinum dispersion. The reaction mixture was then stirred at 50 °C for 1 day, followed by stirring at ambient temperature for another 2 days. The reaction mixture was then filtered through a diatomaceous earth mat to obtain 440 g of a clear product solution. Quantitative NMR analysis of the aliquots (DMSO internal standard, D₂O solvent) revealed that the solution contained 3.17 wt% of the product (75% yield) 4-(neopentylsulfonyl)benzenesulfonic acid. ¹H NMR (D₂O, 400 MHz): δ 1.05 (s, 9H), 3.33 (s, 2H), 7.96–8.01 (m, 4H).

[0284] Synthesis Example 4

[0285] I-12(acid)-4-(neopentylsulfinyl)benzenesulfonic acid

[0286] A 33 wt% aqueous solution of 4-(neopentylthio)benzenesulfonic acid was prepared according to the method of Example 3. A certain amount of this solution (50 g, 63.4 mmol, 1 equivalent) was diluted with water (50 mL) and cooled to 10 °C. A 30 wt% aqueous solution of H₂O₂ (8.6 g, 76 mmol, 1.2 equivalent) was diluted with water (15 mL) and added slowly, maintaining the temperature between 10 °C and 15 °C. The reaction mixture was then stirred at 10 °C for 18 hours, at which point NMR analysis showed complete conversion. Platinum black (0.1 g, 0.5 mmol) was mixed with water (100 g), and the reaction mixture was added to a platinum dispersion. The reaction mixture was stirred at ambient temperature for 1 day and then filtered through a diatomaceous earth mat to obtain 300 g of a clear product solution. Quantitative NMR analysis of the aliquots (DMSO internal standard, D₂O solvent) showed that the solution contained 4.56 wt% of the product (78% yield) of 4-(neopentylsulfinyl)benzenesulfonic acid. 1HNMR (D2O, 400MHz): δ1.09 (s, 9H), 2.86 (dd, 2H, J=14.2Hz, 82.2Hz), 7.73 (d, 2H, J=7.8Hz), 7.92 (d, 2H, J=7.8Hz).

[0287] Synthesis Example 5

[0288] I-5(acid)-2-(4-(tert-butyl)phenoxy)-2-methylpropionic acid

[0289] Ethyl 2-(4-(tert-butyl)phenoxy)-2-methylpropionate was prepared according to the method described in Org. Process Res.Dev. 2007, 11, 431-440. Sodium ethoxide solution (21 wt% in EtOH, 59 g, 182 mmol, 1.1 equivalents) was dissolved in ethyl acetate (30 mL) and heated under reflux for 2 hours. 4-tert-butylphenol (Aldrich, 25.3 g, 168 mmol, 1 equivalent) was added, and the reaction mixture was heated under reflux for 30 minutes. Then ethyl 2-bromoisobutyrate (Sigma-Aldrich) (97 g, 498 mmol, 3 equivalents) was added, and the reaction mixture was heated under reflux for 2 hours. GC analysis showed incomplete conversion of the starting phenol, so an additional 21% sodium ethoxide solution (35 g, 108 mmol, 0.65 equivalence) was added, and heating was continued under reflux for another 30 minutes, at which point GC analysis showed complete conversion of the starting phenol. Heating was then stopped, and the reaction mixture was diluted with water. The layers were separated, and the aqueous layer was extracted with ethyl acetate. The combined organic layers were washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The product was then separated by vacuum distillation at 5 Torr and 40–45 °C to give 41 g of a brown oil (92% yield) of ethyl 2-(4-(tert-butyl)phenoxy)-2-methylpropionate.

[0290] Ethyl 2-(4-(tert-butyl)phenoxy)-2-methylpropionate (41 g, 156 mmol, 1 equivalent) was dissolved in a mixture of THF (500 mL) and water (60 mL). Sodium hydroxide powder (12.9 g, 322 mmol, 2 equivalent) was added, and the reaction mixture was heated to 60 °C for 16 hours. The reaction mixture was cooled to ambient temperature and acidified to approximately pH 2 with concentrated hydrochloric acid solution. The reaction mixture was diluted with water, and the layers were separated. The aqueous layer was extracted with diethyl ether, and the combined organic layers were washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The resulting brown solid showed trace amounts of methacrylic acid, which was removed by azeotropic mixing with a mixture of water, THF, and heptane. Drying under high vacuum gave the product, 33 g of brown solid (91% yield), of 2-(4-(tert-butyl)phenoxy)-2-methylpropionate. 1H NMR (D2O, 400MHz): δ 1.25 (s, 9H), 1.49 (s, 6H), 6.75 (d, 2H, J=8.8Hz), 7.27 (d, 2H, J=8.8Hz), 12.95 (s, 1H).

[0291] Synthesis Example 6

[0292] C-9(Na + Sodium 3-(diphenylphospho)benzenesulfonate (Salt)

[0293] Sodium 3-(diphenylphosphono)benzenesulfonate was prepared according to the method described in New J. Chem. 2003, 27, 1603-1608. Sodium 3-(diphenylphosphono)benzenesulfonate (Sigma-Aldrich) (14.9 g, 41 mmol, 1 equivalent) was dissolved in water (600 mL). 30 g of aqueous H₂O₂ solution (4.65 g, 41 mmol, 1 equivalent) was added, and the reaction was stirred at ambient temperature for 18 hours. The reaction mixture was concentrated to 99 g under reduced pressure. Quantitative NMR analysis of the aliquots (DMAC internal standard, D₂O solvent) showed that the solution contained 15 wt% of the product (95% yield) sodium 3-(diphenylphosphono)benzenesulfonate. ¹H NMR (D₂O, 400 MHz): δ 7.5–7.8 (m, 12H), 8.0–8.1 (m, 2H).

[0294] Synthesis Example 7

[0295] C-10(Na + salt)-

[0296] Sodium 2-hydroxy-2,4,4-trimethylpentane-1-sulfonate

[0297] 2-Methyl-2-neopentylethylene oxide was prepared according to the method employed in Tet. Lett. 1981, 22, 5023-5026. Diisobutylene (Sigma Aldrich) (34.3 g, 306 mmol, 1 equivalent) was mixed with water (1.3 L) and sodium bicarbonate (46.3 g, 551 mmol, 1.8 equivalent). m-chloroperbenzoic acid (77% purity, 82.3 g, 367 mmol, 1.2 equivalent) was added, and the mixture was vigorously stirred for 2 days. The reaction mixture was extracted with diethyl ether and then washed with a cold 10% by weight sodium hydroxide solution. The organic phase was dried over magnesium sulfate and concentrated under reduced pressure to 25 g (64% yield) of 2-methyl-2-neopentylethylene oxide.

[0298] Sodium 2-hydroxy-2,4,4-trimethylpentane-1-sulfonate was prepared according to the method employed in J. Chem. Soc. 1954, 2180-2200. 2-Methyl-2-neopentylethylene oxide (25 g, 195 mmol, 1 equivalent) was mixed with water (195 mL) and sodium sulfite (25 g, 195 mmol, 1 equivalent) and heated in a pressure vessel at 145 °C for 6 hours. The reaction mixture was filtered, and the solid was recrystallized from ethanol and dried to give 5.6 g of white solid (12% yield) sodium 2-hydroxy-2,4,4-trimethylpentane-1-sulfonate. ¹H NMR (D₂O, 400 MHz): δ 0.95 (s, 9H), 1.40 (s, 3H), 1.60–1.68 (m, 2H), 3.11 (s, 2H).

[0299] Synthesis Example 8

[0300] I-10(acid)-N-[[4-(1,1-dimethylethyl)phenyl]sulfonyl]-2-methylalanine

[0301] N-[[4-(1,1-dimethylethyl)phenyl]sulfonyl]-2-methyl-alanine was synthesized by a method adapted from Tetrahedron (1960), 11, 39-51. 2-Aminoisobutyric acid (TCI-US, 9.4 g, 91 mmol), 2.5 N sodium hydroxide (36 mL, 90 mmol), and acetone (36 mL) were added to a 500 mL flask with a three-necked, thermocouple-sheathed, and PTFE-coated magnetic stir bar. A burette A was filled with 50 mL of a solution containing 4-tert-butylbenzenesulfonyl chloride (Oakwood Chemical, 23.623 g, 98.8 mmol) dissolved in 24.3 g of acetone. A burette B was filled with 2.5 N sodium hydroxide (50 mL, 125 mmol). The flask was cooled to 0°C, and then the solution in burettes A and B was added simultaneously in 1 mL increments over a 2-hour period to maintain the internal temperature of the flask between 0°C and 5°C. The solution was then warmed to room temperature and stirred for 18 hours. The contents of the flask were transferred to a one-necked flask, and 53 g of acetone was removed on a rotary evaporator. The flask was cooled to 15°C, and 10% HCl solution was added dropwise with stirring until the pH of the solution reached 2.16. The slurry was filtered through Whatman #1 filter paper. The solid contained a byproduct of tBuC6H4SO3Na, which was removed by washing twice with 250 mL of H2O. The white solid was dried in a vacuum oven at 50°C for 18 hours to give 10.0 g (33.4 mmol, 37% yield) of N-[[4-(1,1-dimethylethyl)phenyl]sulfonyl]-2-methyl-alanine, in acid form, mp 181°C. 1H NMR (DMSO-d6): δ12.5 (br s, 1H), 7.89 (s, 1H), 7.73 (d, 8.5Hz, 2H), 7.57 (d, 8.5Hz, 2H), 1.30 (s, 9H), 1.26 (s, 6H).

[0302] Synthesis Example 9

[0303] I-9(acid)-4-(1,1,3,3-tetramethylbutyl)benzenesulfonic acid

[0304] (1,1,3,3-Tetramethylbutyl)-benzene was synthesized by a method adapted from Tetrahedron Letters (2017), 58(24), 2340-2343. 4-(1,1,3,3-Tetramethylbutyl)phenol (TCI, 69.2 g, 335 mmol), 500 mL of anhydrous DMSO, and triethylamine (40 g, 395 mmol) were charged into a 1 L pressure vessel. The vessel was cooled and purged of air, and then sulfonyl fluoride (Synquest, 38 g, 372 mmol) was condensed into the vessel. The vessel was sealed and stirred at 25 °C for 6 hours. The reaction was repeated on the same scale, and both reactants were then transferred to a 2 L three-necked flask equipped with a dropping funnel, a nitrogen inlet, and a PTFE-coated magnetic stir bar. The solution was bubbled with nitrogen at ambient temperature for 15 minutes using a gas dispersion bubbler. Palladium(II) acetate (Alfa-Aesar, 0.5905 g, 2.630 mmol), 1,3-bis(diphenylphosphino)propane (TCI, 6.78 g, 16.4 mmol), and then triethylamine (275 g, 2.72 mol) were added to a flask. Next, formic acid (TCI, 141 g of 88% solution, 2.70 mol) was added dropwise through a dropping funnel over a period of 2.25 hours, and the reaction proceeded exothermically to 53 °C. The exothermic reaction was controlled using an ice bath 30 minutes after the start of formic acid addition, and then removed. The reaction mixture was then stirred at room temperature for 18 hours. The reaction mixture was extracted with 2 × 250 mL of diethyl ether, and the extracts were combined and washed with 1 L H₂O, 600 mL 0.5N NaOH, 500 mL H₂O, 600 mL 0.5N HCl, and 500 mL H₂O, followed by washing with 250 mL of brine. The diethyl ether solution was dried over magnesium sulfate, filtered, and concentrated using a rotary evaporator. The crude product was distilled using a short-path distillation head (bp 107℃-112℃ / 15mmHg) to give 110.1 g (0.578 mol, 86% yield) of a clear liquid (1,1,3,3-tetramethylbutyl)-benzene. ¹H NMR (400 MHz, CDCl₃) δ 7.42 (m, 2H), 7.31 (m, 2H), 7.19 (m, 1H), 1.79 (s, 2H), 1.41 (s, 6H), 0.76 (s, 9H).

[0305] (1,1,3,3-Tetramethylbutyl)-benzene (8.375 g, 0.044 mol) was dissolved in 40 mL of dichloromethane under an inert atmosphere. The solution was cooled to -20 °C, and chlorosulfonic acid (5.412 g, 0.0464 mol) was added dropwise over a 15-minute period. The solution was then warmed to room temperature and stirred for 4 hours. Dichloromethane was removed under vacuum to give 11.8 g (99%) of 4-(1,1,3,3-tetramethylbutyl)-benzenesulfonic acid as a viscous yellow oil. ¹H NMR (400 MHz, D₂O, reference DHO / sulfonic acid signal) δ 7.64 (d, 8.4 Hz, 2 Hz), 7.39 (d, J = 8 Hz, 2H), 1.62 (s, 2H), 1.22 (s, 6H), 0.61 (s, 9H).

[0306] Synthesis Example 10

[0307] I-14(acid)-hexamethylglutaric acid

[0308] (2,2,3,3,4,4-hexamethylglutaric acid)

[0309] Cumyl chloride was prepared using the method reported in the Journal of Organic Chemistry (1966), 31(4), 1090-3. A jacketed 500 mL flask was equipped with a stir bar, a subsurface inlet, a thermocouple, and a dry ice condenser leading to an alkaline scrubber. α-Methylstyrene (61 g, 0.51 mol) and 300 mL of anhydrous dichloromethane were added to the flask. The flask was cooled to 0 °C, and then anhydrous HCl (22.5 g, 0.62 mol) was bubbled through the reactants over a period of 90 minutes. Nitrogen was then bubbled through the flask over 30 minutes to remove unreacted HCl. Complete conversion of α-methylstyrene to cumyl chloride was confirmed by GC-MS. The dichloromethane solution of cumyl chloride was used directly in the next step without purification.

[0310] 1,1,2,2,3,3-Hexamethylindene was prepared according to the method reported in the Journal of Organic Chemistry (1988), 53(19), 4626-8. A solution of cumyl chloride (0.55 mol) in dichloromethane was added to a 2 L reactor attached to a nitrogen three-way valve and equipped with a dropping funnel, and diluted with dichloromethane to a total volume of 1.25 L. 2,3-Dimethyl-2-butene (58.4 g, 0.69 mol) was added, and the mixture was cooled to -78 °C. Titanium tetrachloride (17.4 g, 0.092 mol) was added over a 3-hour period, and the mixture was then stirred for another 30 minutes. The cooled mixture was quenched by adding a stirred mixture of 250 mL concentrated HCl and 500 mL H₂O. The organic layer was separated and dried with MgSO4, then dichloromethane was removed on a rotary evaporator, and the crude oil was distilled to give 34.8 g (0.172 mol, 31% yield) of 1,1,2,2,3,3-hexamethylindane (bp 52℃-55℃ / 0.4 mm Hg, GC purity 96.4%).

[0311] Hexamethylglutaric acid was prepared using the procedures reported in the Journal of Organic Chemistry (1988), 53(19), 4626-8 and the Journal of Organic Chemistry (1990), 55(6), 1928-32. 1,1,2,2,3,3-hexamethylindene (22.1 g, 0.109 mol), 221 mL of carbon tetrachloride, 221 mL of acetonitrile, 332 mL of H₂O, and periodic acid (354 g, 1.55 mol) were charged into a 2 L reactor. The two-phase mixture was stirred, and then ruthenium trichloride hydrate (0.5475 g, 2.19 mmol) was added, and the mixture was stirred at 30-40 °C for 4 hours. The reactants were cooled to 0 °C, and then 266 mL of diethyl ether was added while still in the mixture. The organic layer was separated, and the aqueous layer was washed with diethyl ether (3 × 100 mL). The organic layers were combined and washed with 180 mL of 5% NaHCO3, followed by 180 mL of brine, and then dried over MgSO4. The solvent was removed by rotary evaporation to obtain 16.03 g of crude hexamethylglutaric anhydride, which was placed in a 500 mL flask containing 130 mL of 40% sodium hydroxide aqueous solution and 130 mL of 2-propanol, and stirred at room temperature for 14 hours. 145 mL of H2O was added and mixed for 10 minutes, followed by extraction of the mixture with 3 × 145 mL of diethyl ether. The aqueous layer was mixed with charcoal and filtered. The filter cake was washed with 30 mL of 1% sodium hydroxide. The aqueous filtrate was treated with 170 mL of concentrated HCl, cooled in an ice bath, and then filtered to give hexamethylglutaric acid (4.57, 0.0211 mol, 19% yield). ¹H NMR (400 MHz, DMSO-d6) δ 1.14 (s, 12H), 1.10 (s, 6H).

[0312] Synthesis Example 11

[0313] I-14(NH4 + (salt)-Hexamethylglutaric acid ammonium salt

[0314] (2,2,3,3,4,4-hexamethylglutaric acid, ammonium salt (1:2)

[0315] A jacketed 500 mL flask was equipped with a stir bar, a subsurface inlet, a thermocouple, and a dry ice condenser leading to an acid scrubber. Hexamethylglutaric acid (2.008 g, 9.28 mmol) and 120 mL of anhydrous diethyl ether were added to the flask, and the mixture was stirred at room temperature for 72 hours. An additional 10 mL of diethyl ether was added, the reactor was cooled to 0 °C, and anhydrous NH3 gas (1.2 g, 67 mmol) was bubbled into the reactants over a 30-minute period. The diethyl ether and excess NH3 were removed under vacuum at room temperature to give diammonium hexamethylglutaric acid (1.958 g, 7.82 mmol, 84% yield). ¹H NMR (400 MHz, DMSO-d6) δ 1.06 (s, 12H), 0.93 (s, 6H).

[0316] Synthesis Example 12

[0317] I-4(Na + Sodium 4-(2,3,3-trimethylbutane-2-yl)benzenesulfonate

[0318] 2,3,3-Trimethylbut-2-ol was prepared by the method described in the Journal of Organic Chemistry (1966), 31(1), 137-42. 50.2 g (0.432 mol) of 2,3,3-trimethylbut-2-ol was added dropwise to 370 mL of concentrated hydrochloric acid and stirred at ambient temperature for 30 minutes. The solution was filtered and washed with cold water to give 58.7 g (0.438 mol, >100% yield) of 2-chloro-2,3,3-trimethylbutane as a slightly moist, fluffy white solid.

[0319] 2-Chloro-2,3,3-trimethylbutane (57.6 g, 0.430 mol) was dissolved in benzene (219 g, 2.80 mol) and dried over CaCl2 for 24 hours. The solution was filtered into a round-bottom flask and 250 mL of chlorobenzene was added. The solution was cooled to -20 °C, and then aluminum chloride (5.81 g, 0.0436 mol) was slowly added while stirring for 10 minutes. Cold brine (50 mL) was added to the solution and stirred for 15 minutes. The solution was transferred to a separatory funnel and washed with water (3 × 50 mL), saturated sodium bicarbonate solution (50 mL), water (3 × 50 mL), and brine (50 mL). The organic layer was dried over CaCl2, and then excess solvent was removed by rotary evaporator to give 55.1 g (0.313 mol, 73% yield) of (2,3,3-trimethylbutane-2-yl)benzene as a pale yellow oil.

[0320] (2,3,3-trimethylbutane-2-yl)benzene (54.9 g, 0.311 mol) was dissolved in 275 mL of dichloromethane. The solution was cooled to -20 °C, and then chlorosulfonic acid (38.4 g, 0.330 mol) was added dropwise over 15 minutes. The solution was stirred at -20 °C for 4 hours. Dichloromethane was removed under vacuum. The resulting solid was slurried in water and neutralized to pH 8 with aqueous NaOH solution. The solution was cooled to 0 °C, and the resulting crystals were filtered and washed with cold water. The solid was dried in a vacuum oven at 50 °C for 24 hours to give 57.2 g (0.206 mol, 66% yield) of sodium 4-(2,3,3-trimethylbutane-2-yl)benzenesulfonate as a white solid. 1H NMR (400MHz, DMSO-d6): δ 7.46 (d, J=8.4Hz, 2H), 7.23 (d, J=8.4Hz, 2H), 1.22 (s, 6H), 0.72 (s, 9H).

[0321] Synthesis Example 13

[0322] C-4(Na + Sodium 4-tert-butylbenzenesulfonate (Salt)

[0323] 50 g of tert-butylbenzene (0.373 mol) was cooled to 0 °C, and then sulfuric acid (91.5 g, 0.91 mol) was added dropwise. The solution was then heated to 80 °C and stirred for 1 hour. The solution was poured into 375 mL of water, and then sodium bicarbonate (30 g, 0.357 mol) and sodium chloride (37.5 g, 0.64 mol) were added sequentially. The solution was cooled to 0 °C for 1 hour, filtered, and the solid was washed with cold water. The solid was dried in a vacuum oven at 100 °C for 18 hours to give 68 g (0.288 mol, 77% yield) of sodium 4-tert-butylbenzenesulfonate as a white flaky solid. ¹H NMR (400 MHz, DMSO-d6): δ 7.56 (d, J = 8.5 Hz, 2H), 7.36 (d, J = 8.5 Hz, 2H), 1.27 (s, 9H).

[0324] Synthesis Example 14

[0325] C-8(Na + Sodium 4-(phenylsulfonyl)benzenesulfonate

[0326] Diphenyl sulfide (101 g, 0.542 mol) was dissolved in 250 mL of dichloromethane. The solution was cooled to 0 °C, and chlorosulfonic acid (71.1 g, 0.610 mol, 1.13 equivalents) was added dropwise through a feeding funnel over a period of 2 hours. The reaction mixture was warmed to room temperature and then stirred for 18 hours. Water (250 mL) was added to the reactor. A distillation head was attached to the reactor, and the solution was heated to 40 °C for 1 hour, then to 90 °C for 30 minutes to remove all trace amounts of dichloromethane. The solution was cooled to ambient temperature. The distillation head was replaced with a reflux condenser, and P25 titanium dioxide (4.32 g, 0.054 mol) was added to the reactor. The solution was cooled to 0 °C, and 30% hydrogen peroxide (148 g, 1.3 mol) was added dropwise through a feeding funnel at a rate that kept the reaction temperature below 20 °C. Next, the solution was heated to 80 °C and stirred for 18 hours. The solution was cooled to ambient temperature and then filtered through a diatomaceous earth mat. The filtrate was cooled to 0°C and neutralized to pH 8 with a 30% NaOH aqueous solution. The solution was filtered, and the solid was washed with cold water. The solid was dried in a vacuum oven at 100°C for 24 hours to give 130 g (0.406 mol, 75% yield) of sodium 4-(phenylsulfonyl)benzenesulfonate as a fine grayish-white powder. ¹H NMR (400 MHz, DMSO-d6): δ 7.96 (d, 8.2 Hz, 4H), 7.84 (d, 8.2 Hz, 2H), 7.67–7.74 (m, 1H), 7.60–7.67 (m, 2H).

[0327] Synthesis Example 15

[0328] I-7(acid)-4,4′-(2,3-dimethylbutane-2,3-diyl)dibenzenesulfonic acid

[0329] Dicumene (20.2 g, 0.0847 mol) was dissolved in 100 mL of dichloromethane under an inert atmosphere. The solution was cooled to -20 °C, and chlorosulfonic acid (20.2 g, 0.173 mol) was added dropwise over a period of 1 hour. The reaction was allowed to warm to room temperature and stirred for 2 hours. The solution was filtered, and the solid was washed with cold dichloromethane. The solid was dried at ambient temperature under a nitrogen atmosphere for 24 hours to give 29 g (0.073 mol, 86% yield) of 4,4′-(2,3-dimethylbutane-2,3-diyl)diphenylsulfonic acid as a fine white powder. ¹H NMR (400 MHz, DMSO-d6): δ 7.42 (d, 8.1 Hz, 4H) 7.14 (d, 8.1 Hz, 4H), 1.21 (s, 12H).

[0330] Synthesis Example 16

[0331] I-1(acid)-3,5-bis(1,1-dimethylethyl)-4-methoxybenzenesulfonic acid

[0332] 3,5-Di-tert-butyl-4-methoxybenzene (50.2 g, 0.228 mol) was dissolved in 150 mL of dichloromethane under an inert atmosphere. The solution was cooled to -20 °C, and chlorosulfonic acid (27.4 g, 0.235 mol) was added dropwise over a period of 1 hour. The reaction was warmed to room temperature and stirred for 2 hours. Water (6.3 mL) was added to the solution. The solution was filtered, and the solid was washed with cold dichloromethane. The solid was dried at ambient temperature under a nitrogen stream for 24 hours to give 64.4 g (0.214 mol, 94% yield) of 3,5-bis(1,1-dimethylethyl)-4-methoxybenzenesulfonic acid as a fine white powder. ¹H NMR (400 MHz, DMSO-d6): δ 7.53 (s, 2H), 3.63 (s, 3H), 1.37 (s, 18H).

[0333] Synthesis Example 17

[0334] I-1(NH4 + (salt)-3,5-bis(1,1-dimethylethyl)-4-

[0335] Methoxybenzenesulfonic acid, ammonium salt (1:1)

[0336] 19.7 g (65.6 mmol) of 3,5-bis(1,1-dimethylethyl)-4-methoxybenzenesulfonic acid and 67 g of H₂O were added to a 250 mL flask equipped with a magnetic stir bar. A pH probe was placed in the solution, and concentrated ammonium hydroxide solution was added dropwise until the pH stabilized between 8 and 9. H₂O was removed by freeze-drying under a vacuum of 0.2 mm Hg, yielding a white solid. The active substance content was determined to be 97.14% by an Ohaus MB45 moisture analyzer at 175 °C. The sample analyzed at 175 °C dissolved in H₂O and showed a neutral pH, indicating the formation of an ammonium salt. 19.1 g (58.4 mmol, 89% yield) of 3,5-bis(1,1-dimethylethyl)-4-methoxybenzenesulfonic acid ammonium salt (1:1) was isolated. 1HNMR (400MHz, DMSO-d6): δ7.50 (s, 2H), 7.13 (br S, 4H), 3.63 (s, 3H), 1.37 (s, 18H).

[0337] Synthesis Example 18

[0338] C-11(acid)-3,5-diisopropylbenzenesulfonic acid

[0339] 1,3-Diisopropylbenzene (50.0 g, 0.308 g) was dissolved in 150 mL of dichloromethane. The solution was cooled to -20 °C, and chlorosulfonic acid (38.3 g, 0.329 mol) was added dropwise over a period of one hour. The reaction was warmed to room temperature and stirred for 4 hours. Water (9 g) was added to the solution. The solution was filtered, and the resulting solid was washed with cold dichloromethane. The solid was dried at ambient temperature under a nitrogen atmosphere for 24 hours to give 69 g (0.285 mol, 93% yield) of 3,5-diisopropylbenzenesulfonic acid as a fine white powder. 1H NMR (400MHz, DMSO-d6): δ7.67 (d, 8.1Hz, 1H), 7.19 (s, 1H), 6.92 (d, 8.1Hz, 1H), 4.01-4.09 (m, 1H), 2.81-2.89 (m, 1H), 1.13-1.19 (m, 12H).

[0340] Synthesis Example 19

[0341] I-8(acid)-3,5-di-tert-butylbenzenesulfonic acid

[0342] A jacketed 500 mL flask was equipped with a stir bar, a subsurface nitrogen inlet, a thermocouple, a dropping funnel, and a dry ice condenser leading to an alkaline scrubber. Check valves were installed before the inlet and scrubber. 1,3,5-tritert-butylbenzene (TCI, 25.09 g, 0.102 mol) and 125 mL of anhydrous dichloromethane were added to the flask. The solution was cooled to -10 °C, and then chlorosulfonic acid (12.3 g, 0.105 mol) was added dropwise over 15 minutes. The mixture was stirred for 4 hours while nitrogen was bubbled through the reactants, followed by the addition of water (0.15 g, 8.3 mmol) and another 30 minutes of nitrogen bubbling. The mixture was filtered through a polypropylene filter funnel with a 10-micron polyethylene sintered disc while cooling, and washed with 150 mL of cooled (-40 °C) dichloromethane. The solid was dried under vacuum at 40 °C and 40 mm Hg to give 15.2 g (0.056 mol, 55% yield) of a grayish-white crude solid of 3,5-di-tert-butylbenzenesulfonic acid. 3,5-Di-tert-butylbenzenesulfonic acid was purified by recrystallization from dichloromethane. ¹H NMR of 3,5-di-tert-butylbenzenesulfonic acid (600 MHz, DMSO-d6): δ 7.47 (d, 2 Hz, 2H), 7.39 (t, 2 Hz, 1H), 1.26 (s, 18H).

[0343] Synthesis Example 20

[0344] I-8(NH4 + Ammonium 3,5-di-tert-butylbenzenesulfonate (Salt)

[0345] 3,5-Di-tert-butylbenzenesulfonic acid (30.2 g, 111.9 mmol) was placed in a glass beaker, and 30 mL of deionized water was added to prepare a slurry. The mixture was stirred until homogeneous. Then, 28%–30% ammonium hydroxide solution was added dropwise until pH = 8–9. The reaction mixture was stirred for 30 minutes and the pH was checked again. The white slurry was then filtered using a glass filter. The solids on the filter were washed with 4 × 25 mL of ice-cold deionized water and then dried overnight at 70–75 °C under a vacuum of 15 inHg. The dried ammonium salt of 3,5-di-tert-butylbenzenesulfonic acid was washed with diethyl ether (3 × 30 mL) and the resulting product was further dried at 70–75 °C under a vacuum of 10–15 inHg for 2 hours. The obtained ammonium product of 3,5-di-tert-butylbenzenesulfonic acid was 26.5 g (82.6% yield). The moisture content of the product was determined to be 0.13% using a Mettler Toledo HR 73 moisture analyzer. The water was evaporated, and the dried solid was washed with 3 × 10 mL of diethyl ether to obtain another 3.8 g of product, but with lower purity. ¹H NMR (methanol-d⁴, 500 MHz): δ 1.37 (s, 18H), 7.56 (t, 1H, J = 1.8 Hz), 7.76 (d, 2H, J = 1.8 Hz).

[0346] Synthesis Example 21

[0347] I-8(K + Potassium 3,5-di-tert-butylbenzenesulfonate (salt)

[0348] 3,5-Di-tert-butylbenzenesulfonic acid (36.6 g, 135.6 mmol) was placed in a glass beaker, and 40 mL of deionized water was added to prepare a slurry. The mixture was stirred until homogeneous. Then, a 30% potassium hydroxide aqueous solution (KOH content minimum 85%) was added dropwise until pH = 8-9. The reaction mixture was stirred for 30 minutes, and the pH was checked again, finding it to be approximately 9-10. The white slurry was then filtered using a glass filter. The solid remaining on the filter was washed with ice-cold deionized water until the pH of the filtrate was 6-7. The obtained solid was dried at 70-75°C under a vacuum of 15 inHg for 3 days. The dried potassium salt of the obtained 3,5-di-tert-butylbenzenesulfonic acid was washed with diethyl ether (3 × 30 mL), and the resulting product was further dried at 70-75°C under a vacuum of 15 inHg for 3 hours. The obtained potassium 3,5-di-tert-butylbenzenesulfonate product was 35.7 g (83.1% yield). The moisture content of the product was determined to be 0% using a Mettler Toledo HR 73 moisture analyzer. The water fraction was evaporated, and the remaining dry solid was washed with 3 × 10 mL of diethyl ether to give another 3.6 g of crude product. ¹H NMR (methanol-d⁴, 500 MHz): δ 1.37 (s, 18H), 7.56 (brs, 1H), 7.76 (d, 2H, J = 1.8 Hz).

[0349] Synthesis Example 22

[0350] I-8(Na + Sodium 3,5-di-tert-butylbenzenesulfonate (Salt)

[0351] 17.6 g (65.2 mmol) of 3,5-di-tert-butylbenzenesulfonic acid was placed in a glass beaker, and 20 mL of deionized water was added to prepare a slurry. The mixture was stirred until homogeneous. Then, 18 mL of a 30% sodium hydroxide aqueous solution (pH 9-10) was added dropwise. The reaction mixture was stirred for 30 minutes and the pH was checked again. The white slurry was then filtered using a glass filter. The solid remaining on the filter was washed with ice-cold deionized water until the pH of the filtrate was 6-7. The obtained solid was dried overnight at 70-75°C under a vacuum of 15 inHg. The dried sodium salt of 3,5-di-tert-butylbenzenesulfonic acid was washed with diethyl ether (3 × 30 mL) and then dried again at 70-75°C under a vacuum of 15 inHg for 2 days. The obtained sodium 3,5-di-tert-butylbenzenesulfonate product was 35.7 g (90.2% yield). The moisture content was determined to be 2.3% using a Mettler Toledo HR 73 moisture analyzer. The water fraction was evaporated, and the remaining dry solid was washed with 3 × 10 mL of diethyl ether to give 7.0 g of additional crude product (moisture content not determined). ¹H NMR (methanol-d⁴, 500 MHz): δ 1.37 (s, 18H), 7.56 (brs, 1H), 7.76 (brs, 2H).

[0352] Synthesis Example 23

[0353] C-12(acid)-3,5-di-tert-butyl-4-hydroxybenzenesulfonic acid

[0354] 2,6-Di-tert-butylphenol (TCI) (50 g, 242.4 mmol) was placed in a three-necked round-bottom flask equipped with a feeding funnel with a gas outlet, a thermometer, a gas inlet, and a mechanical stirrer. The gas outlet was connected to an alkaline scrubber. Then, 100 mL of dichloromethane was added to the reactor, and the stirrer was set to 400 rpm. A nitrogen line was connected to the gas inlet, and a small nitrogen flow was started. The reactor was cooled to -25°C to -20°C, and a mixture of 18 mL of chlorosulfonic acid and 24 mL of anhydrous dioxane was added to the feeding funnel. The dioxane / HSO3Cl solution was added dropwise to the stirred reaction mixture over 25 minutes. The reaction temperature was then raised to -15°C to -10°C, and the reaction mixture was stirred for another 2 hours. The reaction mixture was then warmed to 0°C, and 100 mL of hexane was added to precipitate the 3,5-di-tert-butyl-4-hydroxybenzenesulfonic acid product. The separated solid product was filtered from the reaction mixture and washed with hexane (3 × 50 mL). The organic solution was evaporated on a rotary evaporator. After removing ~15%–20% of the solution, precipitation of additional product was observed. The precipitate was filtered and washed with hexane (3 × 40 mL). All solids were combined and dried at 70–75 °C for 2 h under a vacuum of 10–15 inHg. 60.8 g of 3,5-di-tert-butyl-4-hydroxybenzenesulfonic acid product was obtained (88.0% yield). The formation of a second layer was observed in the organic solution. All solvent was then removed to give an additional 11.0 g of crude product. ¹H NMR (methanol-d⁴, 500 MHz): δ 1.46 (s, 18H), 7.71 (s, 2H).

[0355] Synthesis Example 24

[0356] C-12(NH4 + Salt)-

[0357] 3,5-Di-tert-butyl-4-hydroxybenzenesulfonate ammonium

[0358] 3,5-Di-tert-butyl-4-hydroxybenzenesulfonic acid (20.3 g, 71 mmol) was placed in a glass beaker, and 30 mL of deionized water was added to prepare a slurry. The mixture was stirred until homogeneous. Then, 8 mL of a 28%–30% ammonium hydroxide solution (pH 8–9) was added dropwise. The reaction mixture was stirred for 30 minutes, and the pH was checked again. The resulting white slurry was then filtered through a glass filter. The solids remaining on the filter were washed with ice-cold deionized water until the pH of the filtrate was 6–7. The separated solid product was dried at 70–75 °C for 2 hours under a vacuum of 15 inHg, and then left to stand overnight at ambient pressure and room temperature. The dried ammonium salt of 3,5-di-tert-butyl-4-hydroxybenzenesulfonic acid was washed with diethyl ether (3 × 25 mL), and then dried again at 70–75 °C for 2 hours under a vacuum of 15 inHg. The obtained product, ammonium 3,5-di-tert-butyl-4-hydroxybenzenesulfonate, was 18.4 g (85.6% yield). The moisture content of the product was determined to be ~0.2% using a Mettler Toledo HR 73 moisture analyzer. The water filtrate was evaporated, and the remaining dried solid was washed with 2 × 10 mL of diethyl ether to give another 2.2 g of crude product (moisture content not determined). ¹H NMR (methanol-d4, 500 MHz): δ 1.46 (s, 18H), 7.72 (s, 2H).

[0359] Aggregate Examples

[0360] Comparative Examples 1-12 and Polymerization

[0361] Example 1 - Polymerization of Fluorinated Elastomer from Example 13 -

[0362] Five-hour reaction time at low dispersant concentration

[0363] The following examples illustrate a semi-batch feed emulsion polymerization method for preparing VF2 / HFP / TFE fluoroelastomers, which involves pre-loading a low concentration of dispersant at a constant pressure over a five-hour reaction time and then feeding the monomer. No nucleating agent is used. Comparative Examples 1-12 illustrate the method using comparative dispersants. Examples 1-13 illustrate the method according to the present invention.

[0364] The VF2 / HFP / TFE fluoroelastomer was prepared via a semi-batch feed emulsion polymerization method as follows. A solution containing 2.0 g of disodium phosphate, 1 g–3 g of the dispersant described in Table 1 (depending on molecular weight) to provide the molar amounts shown in Table 1, and deionized deoxygenated water was charged into a 4.0 L reactor to obtain a total of 2,500 g of solution. The reactor was heated to 80 °C, stirred at 700 rpm, and pressurized to 320 psi with a mixture of 25.0% vinylidene fluoride, 73% hexafluoropropylene, and 2% tetrafluoroethylene. To initiate polymerization, 5.0 mL of 2.5% ammonium persulfate and 0.5% disodium phosphate heptahydrate were added to the reactor. A mixture of 50% vinylidene fluoride, 30% hexafluoropropylene, and 20% tetrafluoroethylene was then fed into the reactor to maintain a pressure of 320 psi. An additional initiator was fed into the reactor in increments of 0.0–0.4 mL every 30 minutes to continue polymerization in an attempt to achieve or maintain a monomer flow rate of 80 g / h. The total initiator is listed in Table 1. At the end of the five-hour interval, all feed to the reactor was stopped. The results are reported in Table 1, including start-up time, total monomers fed during the five-hour interval, particle concentration, and condensate.

[0365]

[0366]

[0367] The results of Examples 1-13 show that the method according to the invention for preparing approximately 10% by weight solid batches of fluorinated elastomers using a low-reactive hydrocarbon dispersant enables the polymerization of fluorinated elastomers to be initiated in the presence of a pre-loaded dispersant. As shown in Comparative Examples 2 and 6, some comparative hydrocarbon dispersants, namely linear sodium dodecylbenzenesulfonate (C-2) (Na... + The salt and naphthalenesulfonic acid-formaldehyde condensate (C-6) inhibit the reaction to the extent that no initiation occurs during the five-hour reaction time. Generally, the initiation time of hydrocarbon surfactants is longer than that of the method according to the invention. Furthermore, the method according to the invention provides higher quantities of monomer feed without condensation or with low levels of condensation.

[0368] Except for Comparative Examples 4, 5, and 9, the comparative examples exhibited low monomer feed levels. Comparative Example 4 showed that sodium tert-butylbenzenesulfonate (C-4) (Na + The use of salt did not show inhibition of polymerization and exhibited a high monomer feed, but the agglomerate level was almost half that of the monomer feed, indicating that this comparative dispersant was ineffective for the stability of fluorinated elastomer dispersions. Comparative Example 9 illustrates sodium 2-hydroxy-2,4,4-trimethylpentane-1-sulfonate (C-10) as a dispersant. +The use of salt produces significant coagulation. Comparative Example 5 illustrates the effect of sodium octyl sulfonate (C-5) (Na) as a dispersant. + The use of salt) in this series of examples does not inhibit monomer feed or produce high agglomerates in lower solids batches. However, the following Example 14 and its application... Figure 1 The data plotted in the graph shows the effect of increasing the dispersant concentration. In Example 14, the dispersant sodium octyl sulfonate (C-5) (Na... + The study showed that monomer feed decreased sharply with increasing dispersant concentration, while the dispersant used in the method of the present invention does not cause a significant reduction in monomer absorption.

[0369] Polymerization Example 14

[0370] Fluorinated elastomers -

[0371] The selected dispersant and the increased dispersant concentration of the dispersant of the present invention.

[0372] The same procedure as in Comparative Examples 1-12 and Examples 1-13 was used, except that the dispersant was selected and used at an increased concentration as described in Table 2. The results are reported in Table 2, including start-up time, total monomers fed during the 5-hour interval, as well as particle number, particle size, solids concentration, and agglomerates. Figure 1 It is a graphical representation of the data showing the effect of increasing the dispersant concentration on monomer absorption for the selected comparative dispersant and the dispersant of the present invention.

[0373]

[0374] Refer to Table 2 and Figure 1 Polymerization Example 14 shows that the dispersant 3,5-di-tert-butylbenzenesulfonate ammonium (I-8) (NH4) + (salt) and ammonium 3,5-di-tert-butyl-4-methoxybenzenesulfonate (I-1) (NH4) + The use of salt does not cause a significant decrease in monomer feed rate with increasing dispersant concentration in methods employing pre-loaded dispersants (indicating almost no decrease in reaction rate). Therefore, the final solids concentration of the fluorinated elastomer is high at all dispersant levels. Furthermore, these dispersants have short start-up times. Data show that dispersant levels in the range of 1000 ppm–4000 ppm, typically used to achieve commercial production solids levels, can be successfully used in methods employing the low-reactivity dispersants according to the invention, and pre-loaded dispersants can be used if desired. On the other hand, comparative dispersants show a sharp decrease in monomer absorption with increasing dispersant concentration. Furthermore, the dispersant sodium dodecyl sulfate (C-1) (Na... +Even at low concentrations, dispersant C1 showed poor monomer absorption. At slightly higher concentrations, dispersant C1 showed almost no monomer absorption. In dispersant sodium octyl sulfonate (C-5) (Na... + In the case of salt, monomer absorption is good at low concentrations, as also seen in Comparative Example 5, but the use of dispersant C-5 shows a sharp decrease with increasing concentration. The monomer absorption of dispersant C-5 is very low at 2000 ppm. Furthermore, compared with dispersants I-8 and I-1, dispersant C-5 has a longer start-up time at all concentrations.

[0375] Polymerization Example 15

[0376] High-solids fluorinated elastomer I-3 (acid) dispersant

[0377] The following examples illustrate a high-solids semi-batch feed emulsion polymerization method for preparing VF2 / HFP / TFE fluorinated elastomers by pre-loading a dispersant, 4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonic acid (I-3) (used as an acid). This method employs a perfluorodiiodoalkane compound to provide iodine curing sites as end groups and uses monomers containing iodine curing sites.

[0378] Fluorinated elastomers were prepared by a semi-batch fed emulsion polymerization method carried out in a 40-liter well-stirred reaction vessel at 80°C. A solution of 23.7 g of disodium phosphate heptahydrate in 24 liters of deionized deoxygenated water was charged into the reactor. A solution of 393 g of 6.89% I-3 dispersant (as acid) in water was pumped into the reactor, followed by pumping in 1 liter of deionized deoxygenated water to provide 0.11 wt% I-3 dispersant in the water within the reactor. The reactor was heated to 80°C. After removing trace amounts of oxygen, the reactor was pressurized with a mixture of 4 wt% vinylidene fluoride (VF2), 86 wt% hexafluoropropylene (HFP), and 10 wt% tetrafluoroethylene (TFE). At the end of pressurization, the reactor pressure was 2.2 MPa. 174 ml of an initiator solution of 1% ammonium persulfate and 7.5% disodium phosphate heptahydrate was added to the reactor to initiate polymerization. As the reactor pressure decreased, a mixture of 35 wt% VF2, 37 wt% HFP, and 28 wt% TFE was fed into the reactor to maintain a pressure of 2.2 MPa. After feeding 45 g of this monomer mixture, a mixture of 24.2 g of 72.0 mol% 1,4-diiodoperfluorobutane, 22.7 mol% 1,6-diiodoperfluorohexane, 4.0 mol% 1,8-diiodoperfluorooctane, and 1.2 mol% 1,10-diiodoperfluorodecane was added to the reactor. An additional initiator solution was added to maintain the polymerization rate. After adding 2922 g of the monomer mixture, 4-iodo-3,3,4,4-tetrafluorobutene-1 (ITFB) was introduced into the reactor at a feed rate of 4.83 g ITFB / 1000 g monomer. After a total increment of 8333 g of major monomer (corresponding to a total of 319 ml initiator solution, 20.4 g ITFB, and 13.2 hours), monomer and initiator feeds were stopped. The reactor was cooled and the pressure in the reactor was reduced to atmospheric pressure. The resulting fluorinated elastomer latex had a solids content of 24.6 wt% and a pH of 3.3. The latex was coagulated with aluminum sulfate solution, washed with deionized water, and dried. The fluorinated elastomer had a specific logarithmic viscosity of 0.53 dl / g, a Mooney viscosity ML(1+10) of 68 at 121 °C, and contained 37.3 wt% VF2, 36.6 wt% HFP, 25.9 wt% TFE, and 0.23 wt% TFE. The polymer was compounded on a roller mill with the formulations in Table 3 below by weight:

[0379]

[0380] The test specimens were compression molded from a fluoroelastomer compound at 180°C for 10 minutes and then post-cured at 230°C for 4 hours. The 25% resistance to compression set was measured under aging conditions of 70 hours at 200°C. The tensile strength was 22 MPa, and the elongation at break was 318%.

[0381] Example 15 shows that the VF2 / HFP / TFE fluorinated elastomer can be successfully prepared using a low-reactive hydrocarbon dispersant according to the method of the present invention, and shows that the fluorinated elastomer has the same properties as fluorinated elastomers prepared using fluorinated surfactants.

[0382] Comparative Examples 13-19 and Polymerization Examples 16-22

[0383] PTFE dispersion - 10% by weight solids batch

[0384] Polypropylene glycol nucleating additive

[0385] The following examples illustrate a semi-batch process for preparing aqueous PTFE dispersions by pre-loading a dispersant and feeding TFE in an amount that produces a 10% by weight solid batch. Polypropylene glycol is used as a nucleating additive. Comparative Examples 13-19 illustrate the method using comparative dispersants. Examples 16-22 illustrate the method according to the present invention.

[0386] For the dispersants listed in Table 4, unless otherwise specified in Table 4, use the following polymerization procedure.

[0387] Add 4170 g of deionized degassed water and 250 g of paraffin wax to a 12-liter horizontally mounted jacketed stainless steel autoclave equipped with a dual-blade stirrer. Add an additional 500 g of deionized degassed water containing 0.0297 g of polypropylene glycol (PPG) with a molecular weight of approximately 450 g / mol to the autoclave. Seal the autoclave and place it under vacuum. Pressurize the autoclave to 30 psig (310 kPa) with nitrogen and vent to atmospheric pressure. Pressurize the autoclave with nitrogen and vent twice more. Repeat this pressure / venting cycle three times using tetrafluoroethylene (TFE). Heat the reactor to 60°C without stirring. After the reactor temperature reaches 60°C and is further heated to 90°C, set the stirrer speed to 75 RPM. Add 500 g of deionized degassed water containing 1.176 mmol of the dispersant (DA) listed in Table 3 to the autoclave at 78 ml / min, and then rinse with 200 ml of deionized degassed water.

[0388] Next, TFE was added to the reactor to bring the reactor pressure to 400 psig (2.86 MPa). 200 ml of an initiator solution consisting of 10.0 g (70% active) disuccinic acid peroxide and 990.0 g deionized water was added to the reactor at a rate of 80 ml / min. Start-up times were recorded and are shown in Table 4. After start-up, the autoclave pressure was brought back to 400 psig (2.86 MPa) with supplemental TFE and maintained at this pressure throughout the polymerization duration by continuously adding supplemental TFE. At start-up, 30 ml of a solution consisting of 0.5 g ferric sulfate (II) heptahydrate in 499.5 g deionized water was added to the reactor at a rate of 100 ml / min. After adding the prescribed amount of supplemental TFE to the reactor since start-up to produce 10% by weight solids (700 g), the stirrer was stopped, which confirmed the completion of the polymerization reaction. After stopping the stirrer, the reactor was vented to atmospheric pressure, cooled to 80°C, and then the dispersion was discharged. After the dispersion cools, the solid wax is separated from the dispersion and the dispersion is filtered to remove undispersed solids. The reactor is opened and all adhering polymer is removed from the reactor. The reactor cleaning solution is combined with the filtered solids and recorded as total wet condensate. This total wet condensate includes polymer, paraffin wax, and water.

[0389] The polymer dispersion was coagulated by adding an aqueous solution of ammonium carbonate followed by vigorous stirring until the polymer was completely separated from the water. The resulting polymer was dried in a vacuum oven at 110°C for 12 hours. The results are reported in Table 4, including start-up time, start-up rate, interval time, solids weight % (%), particle size, wet coagulated product, and melting point.

[0390]

[0391]

[0392] The results of Examples 16-22 show that the method according to the invention, using a low-reactive hydrocarbon dispersant, enables the polymerization of PTFE to be initiated in the presence of a pre-loaded dispersant and polymerizes PTFE into 10% solids with a low condensate level. On the other hand, Comparative Examples 13-16 and 18 either did not start after 60 minutes or stopped polymerization shortly after initiation. Sodium tert-butylbenzenesulfonate (C-4) (Na...) was used. + Comparative Example 17, using sodium 4-(phenylsulfonyl)-benzenesulfonate (C-8) as a dispersant, did not stop the polymerization, but the level of condensate was extremely high, indicating that this comparative dispersant was ineffective for the stability of the PTFE dispersion, even at low solids levels. + Comparative Example 19, which used salt as a dispersant, was also able to start, but again produced extremely high levels of condensate, indicating ineffective stability.

[0393] Polymerization Example 23

[0394] PTFE dispersions – with increased dispersant concentration compared to the selected comparative dispersants and the dispersants of this invention. 25%-30% solids in batches

[0395] Polypropylene glycol nucleating agent

[0396] The following examples illustrate a semi-batch process for preparing an aqueous PTFE dispersion having both a selected comparative dispersant and the dispersant of the present invention by pre-loading a portion of the dispersant and feeding TFE in an amount that produces a batch of 25-30 wt% solids. The remaining dispersant is fed into the reactor with a delay after polymerization begins. This process of pre-loading a portion of the dispersant and subsequently adding the remaining dispersant in the batch is referred to herein as “separate addition of the dispersant.” Polypropylene glycol is used as a nucleating additive.

[0397] For the dispersants selected in Table 5, unless otherwise specified in Table 5, the following polymerization procedures are used. Polymerizations in runs 1-3 (in this invention) and runs 4-5 (comparative) are carried out using equal masses of dispersant. Polymerizations in runs 6-7 (in this invention) and runs 8-9 (comparative) are carried out using equimolar amounts of dispersant. The concentrations (ppm) of the dispersant listed in Table 5 are relative to the amount of water present at the end of the batch.

[0398] Add 4000 g of deionized degassed water and 250 g of paraffin wax to a 12-liter horizontally mounted jacketed stainless steel autoclave equipped with a dual-blade stirrer. Add 500 g of deionized degassed water containing 0.09 g of polypropylene glycol (PPG) with a molecular weight of approximately 450 g / mol to the autoclave. Seal the autoclave and place it under vacuum. Pressurize the autoclave to 30 psig (310 kPa) with nitrogen and then purge to atmospheric pressure. Pressurize the autoclave with nitrogen and purge twice more. Repeat this pressure / purge cycle three times using tetrafluoroethylene (TFE). Heat the reactor to 60°C without stirring. After the reactor temperature reaches 60°C and is further heated to 90°C, set the stirrer speed to 75 RPM. For polymerizations using equimolar amounts of dispersant (runs 1-3, this invention) and 4-5, this comparison), an aqueous solution containing 8.1 g of the dispersant listed in Table 5, prepared using deionized degassed water, was added to the autoclave at a rate of 78 ml / min. For polymerizations using equimolar amounts of dispersant (27.7 mmol), this comparison, an aqueous solution containing the dispersant listed in Table 5, prepared using deionized degassed water (equal to half the total amount in Table 5), was added to the autoclave at a rate of 78 ml / min. After adding the dispersant, 87 ml of an ammonium persulfate (APS) solution consisting of 0.4 g of APS in 500 g of deionized degassed water was added at a rate of 76 ml / min.

[0399] TFE was added to the reactor to bring the reactor pressure to 400 psig (2.86 MPa). The stirrer speed was increased to 90 RPM. 300 ml of an initiator solution consisting of 21.0 g (70% active) disuccinic acid peroxide and 879.0 g deionized degassed water was added to the reactor at a feed rate of 80 ml / min. The polymerization reaction was considered to have started after the maximum pressure drop of 10 psi (69 kPa) observed during the injection of the initiator solution. The autoclave pressure was brought back to 400 psig (2.86 MPa) with TFE and maintained at this pressure for the duration of polymerization by continuous addition of supplemental TFE. At startup, a maintenance initiator solution containing 21.0 g (70% active) disuccinic acid peroxide and 879.0 g deionized degassed water was added simultaneously at a feed rate of 3 ml / min until the end of the batch. Meanwhile, 100 ml of a solution consisting of 0.5 g ferric sulfate (II) heptahydrate in 499.5 g deionized water was added to the reactor at a feed rate of 100 ml / min. After 250 g of TFE had been fed since startup, for runs 1-3 (in this invention) and runs 4-5 (comparative) using equal masses of dispersant, an aqueous solution prepared with deionized degassed water containing 8.1 g of the dispersant listed in Table 5 was fed into the reactor at a feed rate of 10 ml / min. However, as shown in Table 5, run 4 resulted in no startup, while run 5 resulted in the batch being started and stopped after the feed rate dropped to zero, thus no additional dispersant was added to the reactor. For runs 6-7 (in this invention) and runs 8-9 (comparative), equimolar amounts of dispersant were added at the same rate, but the solution contained 27.7 mmol of each dispersant listed in Table 5 (equal to half the total amount listed in Table 5). The polymerization reaction was deemed complete after a total of 2100 g of TFE had been added to the reactor since start-up. After stopping the agitator, the reactor was vented to atmospheric pressure, cooled to 80°C, and the dispersion was discharged. After cooling, the solid wax was separated from the dispersion, and the dispersion was filtered to remove undispersed solids. The reactor was opened, and all adhering polymer was removed from the reactor. The reactor cleaning solution was combined with the filtered solids and recorded as total wet condensate. Total wet condensate was reported as a percentage of wet condensate formed based on the weight of the dispersed polymer.

[0400] The results are reported in Table 5, including dispersant concentration, start-up time, start-up rate, interval time, solids weight % , particle size, wet condensate, melting point, and space-time yield (STY).

[0401] To calculate the space-time yield (STY), space is the volume of the reactor, time is the time from the start of the polymerization reaction until its completion, and yield is the weight of the dispersed polymer formed. STY is expressed in this paper as gm / l-hr (of the dispersed polymer).

[0402]

[0403]

[0404] Referring to Table 5, Example 23 shows in Run Nos. 1-3 that the dispersant is 4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonate ammonium)(I-3)(NH4 + (salt), ammonium 3,5-di-tert-butylbenzenesulfonate (I-8)(NH4) + (salt) and ammonium 3,5-di-tert-butyl-4-methoxybenzenesulfonate (I-1) (NH4) + The use of salts in a method employing the separate addition of dispersing agents produces high-solids PTFE batches in the presence of high equal amounts of dispersing agents. High PTFE solids concentrations are achieved with a small amount of condensate. Data indicate that total dispersant levels in the range of 1000 ppm to 4000 ppm, typically used to achieve solids levels in commercial production, can be successfully used in the method employing the low-reactivity dispersant according to the invention, and, if desired, the separate addition of the dispersant can be used.

[0405] In run number 4, the same amount of sodium octyl sulfonate (C-5) (Na) was used as the dispersant in dispersants I-3, I-8, and I-1. + The salt did not cause startup within one hour in the presence of the pre-loaded dispersant. In run number 5, sodium octyl sulfate (C-7) was used as a comparative dispersant in the same weight as the dispersants used in I-3, I-8, and I-1. + Salt caused the batch to stop because the TFE feed rate dropped to zero in the presence of the pre-loaded dispersant. Similar favorable results (i.e., low condensate and high solids levels) were again achieved in runs 6 and 7, where dispersants I-3 and I-1 were used in equimolar amounts in a method of adding dispersants separately. A comparison of dispersants used in run 8 with the same molar amounts of I-3 and I-1 dispersants was made with sodium octyl sulfonate (C-5) (Na... + Salts lead to high solids, but with longer intervals and significant condensation. A comparison of dispersants used in run number 9 with the same molar amounts as those used in I-3 and I-1: Dispersant sodium octyl sulfate (C-7) (Na... +The salt content resulted in slightly lower solids, but with a longer interval time than run number 8, and very high condensate production. The space-time yield (STY) in the methods using dispersants I-3, I-8, and I-1 in equal-weight runs and in the methods using dispersants I-3 and I-1 in equal-molar runs was higher than the STY of dispersants C-5 and C-7 in equal-molar runs (the STY of dispersants C-5 and C-7 was 0 in equal-weight runs because no PTFE was produced).

[0406] Comparative Example 20 and Polymerization Example 24

[0407] PTFE dispersion - 10% by weight solids batch

[0408] Perfluoropolyether acid nucleating additive

[0409] The following examples illustrate a semi-batch process for preparing aqueous PTFE dispersions by pre-loading a dispersant and feeding TFE in an amount that produces a 10% by weight solids batch. Perfluoropolyether acid is used as a nucleating additive. Comparative Example 20 illustrates a method using a comparative dispersant. Polymerization Example 24 illustrates the method according to the invention.

[0410] Comparative Example 20

[0411] 600 g of natural paraffin, 1.6 g of succinic acid, and 19.5 L of deionized water were charged into a nominal 10-gallon jacketed cylindrical stainless steel reactor with a length-to-diameter ratio of 1.5, equipped with a paddle agitator. An aqueous solution (160 mL) containing 4.0 g of a carboxylic acid-functionalized perfluoropolyether acid polymerized from hexafluoropropylene oxide with a number average molecular weight of approximately 1500 and 2.4 g of tert-butanol was added, and the reactor was sealed. The reactor was purged with nitrogen to greater than 20 PSIG and then purged to 5 PSIG three times. After heating to 65°C, the reactor was stirred at 70 RPM, then pressurized with nitrogen to 400 PSIG and leaks were checked. After purging and reducing the stirring rate to 20 RPM, the reactor was purged with TFE to greater than 25 PSIG and then purged to 5 PSIG three times. The agitator was set to 70 RPM, and the contents were heated to 90°C. Add 1.2 g of linear sodium dodecylbenzenesulfonate (C-2) (Na) to the reactor at a rate of 100 mL / min. + An aqueous solution of 1.0% (m / v) bis(2-di ...

[0412] Polymerization Example 24

[0413] Repeat the procedure of Comparative Example 20, except that 1.0 g of sodium 3,5-di-tert-butylbenzenesulfonate (I-8) (Na) was added to the reactor at a rate of 100 mL / min. + An aqueous solution of the salt dispersant was used. Furthermore, polymerization began (start-up), as indicated by a pressure drop of 10 PSIG, occurring at a start-up time of 45 minutes (start-up rate of 0.22 PSIG / min). Then, additional TFE was fed into the reactor at a rate sufficient to maintain a constant pressure of 400 PSIG. Additionally, after start-up, 100 mL of an aqueous solution containing 0.1 g of ferrous sulfate heptahydrate was added at a rate of 100 mL / min. After a total of 2268 g of TFE had been added since start-up, the TFE addition valve was closed, the agitator was stopped, and the reactor was vented. The reaction time was 36 minutes. The resulting dispersion containing 11.30% polymer was discharged from the reactor and allowed to cool. The dispersion was found to have an initial particle size of 195 nm. After discharging the dispersion, 192 g of a condensate containing water, paraffin, and polymer was left in the reactor.

[0414] The results of Comparative Example 20 and Polymerization Example 24 are summarized in Table 6, including the results reported in Table 6, including start-up time, start-up rate, interval time, solids weight %, particle size and wet condensate.

[0415]

[0416] The results of Example 24 again demonstrate that the method according to the invention, using a low-reactive hydrocarbon dispersant, enables the polymerization of PTFE to be initiated and polymerized to 10% solids in the presence of a pre-loaded dispersant. On the other hand, Comparative Example 16, using a comparative dispersant, did not initiate polymerization after 45 minutes.

[0417] Polymerization Example 25

[0418] PTFE dispersion - 10% by weight solids batch

[0419] (I-8)(NH4 + Salt dispersant

[0420] Perfluorinated ionomer particle nucleating additive

[0421] The following examples illustrate the invention of delayed addition of ammonium 3,5-di-tert-butylbenzenesulfonate (I-8)(NH4) + A semi-batch process is used to prepare aqueous PTFE dispersions by feeding TFE with a salt dispersant and producing 10% by weight solids. Perfluorinated ionomer particles, as disclosed in U.S. Patent 6,916,853, are used as nucleating additives.

[0422] Add 40 grams of natural paraffin and 1.5 liters of deionized water to a nominal 1-gallon jacketed cylindrical stainless steel horizontal reactor equipped with a paddle agitator.

[0423] An aqueous solution (500 mL) containing 0.4 g ascorbic acid, 0.27 g ammonium pentaborate octahydrate, 3 g tert-butanol, 0.15 g perfluorinated ionomer particles as disclosed in U.S. Patent 6,916,853, 0.015 g ferrous sulfate heptahydrate, 60 μL of 25-30% ammonium hydroxide and 2 g of potassium di-tert-butylphosphate was added to the reactor.

[0424] The reactor was then sealed and heated to 40°C. The reactor was purged with nitrogen to greater than 20 PSIG and then vented to 5 PSIG three times. The reactor was pressurized with nitrogen to 400 PSIG and leaks were checked. After venting, the reactor was purged with TFE to greater than 25 PSIG and then vented to 5 PSIG three times. After heating the reactor to 65°C, setting the stirrer to 40 RPM, and pressurizing the reactor to 350 PSIG, 40 mL of initiator solution was pumped into the reactor at a rate of 10 mL / min. The initiator solution contained 0.075% tert-butyl hydroperoxide (TBHP). After the 40 mL initiator solution was used, the stirrer was set to 100 RPM and the initiator solution was pumped at 2 mL / min. After polymerization had started (start-up), as indicated by the pressure drop of 10 PSIG, additional TFE was fed into the reactor at a rate sufficient to maintain a constant pressure of 350 PSIG. The temperature was maintained at 65°C. After adding 45g TFE since startup, a pump containing 1.16% ammonium 3,5-di-tert-butylbenzenesulfonate (I-8)(NH4) was started at a rate of 10ml / min. + An aqueous solution of (salt) was added until the reaction was complete. After a total of 227 g of TFE was added since start-up, the TFE addition valve was closed, the stirrer was stopped, and the reactor was vented. The reaction time was 36 minutes. The resulting dispersion containing 10.04 wt% polymer was discharged from the reactor and allowed to cool. After removing paraffin, the dispersion was found to have an original particle size of 144.5 nm. After discharging the dispersion, 27 g of a condensate containing a mixture of water, paraffin, and polymer was left in the reactor.

[0425] Polymerization Example 26

[0426] High solids PTFE dispersion

[0427] (I-3)(NH4 + Salt dispersant

[0428] No nucleating agent

[0429] The following examples illustrate the method of pre-loading 4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonate ammonium)(I-3)(NH4) + A semi-batch process for preparing aqueous PTFE dispersions is used, in which TFE is fed as a salt dispersant and the resulting batch contains approximately 30% by weight solids. No nucleating agents are used.

[0430] Add 4340 g of deionized degassed water and 250 g of paraffin wax to a 12-liter horizontally mounted jacketed stainless steel autoclave equipped with a dual-blade stirrer. Add 500 g of a dispersant containing 15.657 g of I-3 (NH4) to the autoclave. +The reactor contained 0.058 g of deionized degassed water containing salt and 0.092 g of ferric sulfate (II) heptahydrate. The autoclave was sealed and placed under vacuum. The autoclave pressure was increased to 30 psig (310 kPa) with nitrogen and then vented to atmospheric pressure. The autoclave was pressurized with nitrogen and vented twice more. This pressure / venting cycle was repeated three times using tetrafluoroethylene (TFE). The reactor was heated to 60°C without stirring. After the reactor temperature reached 60°C and was further heated to 90°C, the stirrer speed was set to 75 RPM. 683.3 g of TFE was added to the reactor to bring the reactor pressure to 400 psig (2.86 MPa). The stirrer speed was then increased to 90 RPM. 370 ml of an initiator solution consisting of 45.0 g (70% active) disuccinic acid peroxide and 855.0 g deionized degassed water was added to the reactor at a feed rate of 100 ml / min. 7.6 minutes after the start of initiator injection, the reactor pressure dropped by 10 psi (69 kPa) from the maximum pressure observed during initiator solution injection. The autoclave pressure was brought back to 400 psig (2.86 MPa) with TFE and maintained at this pressure for the duration of polymerization. After 250 g of TFE had been fed since start-up, a maintenance initiator solution containing 45.0 g (70% active) disuccinic acid peroxide and 855.0 g deionized degassed water was added simultaneously at a feed rate of 2 ml / min until the end of the batch. 97.7 minutes after start-up, 2300 g of TFE and 144 ml of maintenance initiator solution were added to the reactor. The agitator was stopped, the reactor was vented to atmospheric pressure, cooled to 80°C, and then the dispersion was discharged. After cooling, 160 g of solid wax was separated from the dispersion and the dispersion was filtered to remove undispersed solids. The reactor was opened and all attached polymer was removed from the reactor. The reactor cleaning solution was combined with the filtered solids and recorded as 115 g of total wet coagulate. The total wet coagulate formed contained water, paraffin wax, and polymer. An aqueous dispersion with 29.7% solids and an average volumetric particle size Dv(50) of 220 nm was prepared. The polymer was coagulated by diluting the dispersion to approximately 10 wt% solids and by adding 10 vol% of a 20 wt% aqueous solution of ammonium carbonate, followed by vigorous stirring until the polymer was completely separated from the water. The polymer was dried in a vacuum oven at 110 °C for 12 hours. The melting point of the polymer, measured by DSC during the first heating, was 334.44 °C.

[0431] Polymerization Example 27

[0432] Preparation of high-solids PTFE dispersions and fine powders

[0433] (I-8)(Na + Salt dispersant

[0434] Polypropylene glycol nucleating additive

[0435] The following examples illustrate a semi-batch process for preparing an aqueous PTFE dispersion by adding sodium 3,5-di-tert-butylbenzenesulfonate (I-8) (Na+ salt) dispersant immediately after start-up and feeding TFE in an amount that produces approximately 35% by weight of solids. Polypropylene glycol is used as a nucleating additive. Fine PTFE powder is prepared from the dispersion.

[0436] 600 g of natural paraffin, 1.6 g of succinic acid, and 18.1 L of deionized water were charged into a nominal 10-gallon jacketed cylindrical stainless steel reactor with a length-to-diameter ratio of 1.5, equipped with a paddle agitator. 100 mL of an aqueous solution containing 0.075 g of polypropylene glycol with a number-average molecular weight of approximately 450 was added, and the reactor was sealed. The reactor was purged with nitrogen to a pressure greater than 20 PSIG and then vented to 5 PSIG three times. After heating to 65°C, the reactor was stirred at 70 RPM, then pressurized with nitrogen to 400 PSIG and leaks were checked. After venting and reducing the stirring rate to 20 RPM, the reactor was purged with TFE to a pressure greater than 25 PSIG and then vented to 5 PSIG three times, then 40 mL of an aqueous solution containing 0.08 g of ammonium persulfate was added. The agitator was set to 70 RPM and the contents were heated to 90°C. TFE was added to the reactor until a pressure of 400 PSIG was reached. To initiate polymerization, 140 mL of a 1.0% (m / v) aqueous solution of bis(2-di) succinyl peroxide (DSP) was added at a rate of 80 mL / min. After polymerization had started (start-up), additional TFE was fed into the reactor at a rate sufficient to maintain a constant pressure of 400 PSIG, as indicated by a pressure reduction of 10 PSIG. Additionally, immediately after start-up, 2940 mL of a solution containing 50 g of sodium 3,5-di-tert-butylbenzenesulfonate (I-8) (Na) was added at a rate of 80 mL / min. + An aqueous solution of ferrous sulfate (S(2-)) was prepared, along with 80 mL of an aqueous solution containing 0.08 g of L-ascorbic acid and 100 mL of an aqueous solution containing 0.1 g of ferrous sulfate heptahydrate. After adding a total of 10.9 kg of TFE since start-up, the TFE addition valve was closed, the stirrer was stopped, and the reactor was vented. The reaction time was 164 minutes. The resulting dispersion containing 35.34% polymer was discharged from the reactor and allowed to cool. The dispersion was found to have an initial particle size of 230 nm. After discharging the dispersion, 1132 g of a coagulated residue containing water, paraffin, and polymer was left in the reactor.

[0437] The dispersion was condensed in a 3L container with 12% solids and dried in a static oven at 150°C for 24 hours. The prepared PTFE fine powder had an SSG of 2.1666, thus exhibiting properties comparable to PTFE fine powder prepared using fluorinated surfactants.

[0438] Polymerization Example 28

[0439] High solids PTFE dispersion

[0440] (I-3)(NH4 + Salt dispersant

[0441] Perfluoropolyether acid nucleating additive

[0442] The following examples illustrate a semi-batch process for preparing aqueous PTFE dispersions using a 4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonate ammonium)(I-3)(NH4+ salt) dispersant, wherein the addition of the dispersant is delayed until after start-up, and TFE is fed in an amount that produces approximately 32% by weight of solids in the batch. Perfluoropolyether acid is used as a nucleating additive.

[0443] A nominal 10-gallon jacketed cylindrical stainless steel reactor with a length-to-diameter ratio of 1.5, equipped with a paddle agitator, was charged with 600 g of natural paraffin wax, 2.0 g of succinic acid, 0.05 g of Tomadol 23-1 nonionic surfactant (Evonik Industries AG, Essen, Germany), and 19.5 L of deionized water. An aqueous solution (160 mL) containing 8.0 g of perfluoropolyether acid polymerized from hexafluoropropylene oxide with a number average molecular weight of approximately 1500 and 8 g of tert-butanol was added, and the reactor was sealed. The reactor was purged with nitrogen to greater than 20 PSIG and then purged to 5 PSIG three times. After heating to 65°C, the reactor was stirred at 70 RPM, then pressurized with nitrogen to 400 PSIG, and leaks were checked. After purging and reducing the stirring rate to 20 RPM, the reactor was purged with TFE to greater than 25 PSIG and then purged to 5 PSIG three times. Set the stirrer to 70 RPM and heat the contents to 90°C. Add TFE to the reactor until a pressure of 400 PSIG is reached. To initiate polymerization, add 300 mL of an aqueous solution containing 4.5 g of bis(succinyl) peroxide (DSP) at a rate of 80 mL / min. After polymerization has started (start-up), as indicated by a pressure reduction of 10 PSIG, feed additional TFE into the reactor at a rate sufficient to maintain a constant pressure of 400 PSIG. After adding 45 g of TFE since start-up, add 300 mL of an aqueous solution containing 0.24 g of ferrous sulfate heptahydrate and 0.3 g of L-ascorbic acid at a rate of 45 mL / min. After adding 181 g of TFE since start-up, add 2200 mL of a solution containing 44 g of ammonium 4-((4-(tert-butyl)phenyl)sulfonyl)benzenesulfonate)(I-3)(NH4) at a rate of 80 mL / min. + An aqueous solution of the (salt) dispersant was prepared. After a total of 9979 g of TFE was added since startup, the TFE addition valve was closed, the stirrer was stopped, and the reactor was vented. The reaction time was 197 minutes. The resulting dispersion containing 32.62% polymer was discharged from the reactor and allowed to cool. The dispersion was found to have an initial particle size of 247 nm. After discharging the dispersion, 930 g of a coagulated mixture containing water, paraffin, and polymer was left in the reactor.

[0444] Polymerization Example 29

[0445] High solids PTFE dispersion

[0446] (I-8)(Na + Salt dispersant

[0447] Dispersed particles of fluorinated ionomer nucleating additives

[0448] tert-butyl hydrogen peroxide initiator

[0449] The following examples illustrate the use of sodium 3,5-di-tert-butylbenzenesulfonate (I-8) (Na + A semi-batch process for preparing aqueous PTFE dispersions using salt-based dispersants, some of which are pre-loaded and others added immediately after startup, i.e., "separate addition". TFE is fed in an amount producing approximately 41% by weight of solids in the batch. Tert-butyl hydroperoxide is used as an initiator. Dispersed particles of the fluorinated ionomer are used as nucleating additives as disclosed in U.S. Patent 8,153,738.

[0450] 600 g of natural paraffin and 19.5 L of deionized water were charged into a nominal 10-gallon jacketed cylindrical stainless steel reactor with a length-to-diameter ratio of 1.5, equipped with a paddle stirrer. A 100 mL aqueous solution containing 3.0 g of a fluorinated ionomer prepared by the method disclosed in U.S. Patent 6,150,426 and 5.0 mL of tert-butanol was added, and the reactor was sealed. The reactor was purged with nitrogen to greater than 20 PSIG and then purged to 5 PSIG three times. After heating to 65°C, the reactor was stirred at 70 RPM, then pressurized with nitrogen to 400 PSIG, and leaks were checked. After purging and reducing the stirring rate to 20 RPM, the reactor was purged with TFE to greater than 25 PSIG and then purged to 5 PSIG three times. Set the stirrer to 70 RPM, then add 600 mL of 0.5% (m / v) L-ascorbic acid aqueous solution and 1250 mL of 2% (m / v) sodium 3,5-di-tert-butylbenzenesulfonate (I-8)(Na) at a rate of 80 mL / min. + Aqueous solution of tert-butyl hydroperoxide (TBHP). TFE was added until a pressure of 390 PSIG was reached. To initiate polymerization, 80 mL of 1.0% (m / v) tert-butyl hydroperoxide (TBHP) aqueous solution was added at a rate of 80 mL / min, and start-up was observed. TFE was then fed to maintain a constant pressure of 400 PSIG. After start-up, for the remainder of the batch, another 1.0% (m / v) TBHP aqueous solution was added at a rate of 2.0 mL / min. Additionally, immediately after start-up, 1250 mL of 2% (m / v) sodium 3,5-di-tert-butylbenzenesulfonate aqueous solution was added at a rate of 80 mL / min. After a total of 13.15 kg TFE had been added since start-up, the TFE addition valve was closed, the stirrer was stopped, and the reactor was vented. The reaction time was 68 minutes. The resulting dispersion containing 40.66% polymer was discharged from the reactor and allowed to cool. The dispersion was found to have an initial dispersion particle size of 236 nm. After the dispersion was discharged, 253 g of condensate containing approximately 6 g of water, 241 g of paraffin, and 6 g of PTFE (representing a 0.05% mass loss) was left in the reactor. The SSG of the PTFE polymer separated after coagulation and drying was 2.1843.

[0451] Polymerization Example 30

[0452] High solids PTFE dispersion

[0453] (I-1)(NH4 + Salt dispersant

[0454] Dispersed particles of fluorinated ionomer nucleating additives

[0455] tert-butyl hydrogen peroxide initiator

[0456] The following examples illustrate a semi-batch process for preparing aqueous PTFE dispersions using ammonium 3,5-di-tert-butyl-4-methoxybenzenesulfonate (I-1) (NH4+ salt) dispersants, some of which are pre-loaded and some added immediately after startup, i.e., “separate addition”. TFE is fed in an amount producing approximately 41% by weight of solids in the batch. Tert-butyl hydroperoxide (TBHP) is used as an initiator. Dispersed particles of the fluorinated ionomer are used as nucleating additives as disclosed in U.S. Patent 8,153,738.

[0457] Repeat the steps of Example 29, except that 2% (m / v) 3,5-di-tert-butyl-4-methoxybenzenesulfonate ammonium (I-1)(NH4) is added at a rate of 80 mL / min before startup. + An aqueous solution of NH4+ was used as a dispersant. Additionally, immediately after startup, 1289 mL of 2% (m / v) ammonium 3,5-di-tert-butyl-4-methoxybenzenesulfonate (I-1)(NH4+) was added at a rate of 80 mL / min. + Aqueous solutions of salts are used as dispersants.

[0458] The reaction time was 56 minutes. The resulting dispersion containing 40.55% polymer was discharged from the reactor and allowed to cool. The dispersion was found to have an initial particle size of 227 nm. After discharging the dispersion, 630 g of a condensate containing approximately 161 g of water, 322 g of paraffin, and 161 g of PTFE (representing a 1.2% mass loss) was left in the reactor. The SSG of the PTFE polymer separated after coagulation and drying was 2.1920.

[0459] Explanation of hydrocarbons

[0460] Examples of the reactivity of the dispersant with the tert-butyl hydroperoxide initiator

[0461] Reactive Example 1

[0462] tert-butyl hydroperhydrogenation loss

[0463] This embodiment illustrates the use of a dispersant in the method according to the invention. Hydrogen loss of tert-butyl peroxideComparison with results observed using a comparative dispersant in the same test.

[0464] Prepare a 100 mM sodium dihydrogen phosphate / disodium hydrogen phosphate buffer solution to pH 7.00 ± 0.02 at ambient temperature. Deoxygenate the solution by bubbling with nitrogen. Prepare solutions of 10 ± 1 mM of the dispersant listed in Table 5 and 70 ± 1 mM of tert-butyl hydroperoxide in the previously prepared buffer solution under a nitrogen atmosphere (<10 ppm / v O2). Also prepare a control solution of 10 ± 1 mM of the dispersant in a pH 7 buffer solution, but without tert-butyl hydroperoxide. Transfer 0.55 ± 0.1 mL of each solution to two separate borosilicate glass tubes (5.0 mm outer diameter, 0.77 mm wall thickness). Connect these tubes to a vacuum manifold, remove approximately 1 / 3 of the nitrogen headspace, and then flame-seal the tubes. Heat the sealed tubes in an oven at 95 °C for 72 h. After heating, cool the tubes to ambient temperature, scratch them with a file, and crack them. Remove the solutions.

[0465] Liquid chromatography (LC) was used to determine the amount of dispersant in heated control solutions and heated solutions containing tert-butyl hydroperoxide. The solution was diluted 100X in LC-grade water. A secondary calibration curve with at least five points was prepared using the dispersant in question. Reversed-phase LC was used with a gradient of 95:5 2mM ammonium acetate aqueous solution: acetonitrile and acetonitrile, using C1... 18 Column. Quantitative LC was performed to determine the percentage reduction in dispersant concentration, i.e. Hydrogen loss of tert-butyl peroxide % by weight, if possible, using a UV detector (if the dispersant under consideration is reported in a UV spectrum above 200 nm), otherwise using a mass spectrometer.

[0466] The test results for the dispersant are listed in Table 7.

[0467]

[0468]

[0469] The results showed that dispersants I-3 and I-8 exhibited significantly lower wt% tert-butyl peroxide hydroxide loss compared to the comparative dispersants C-1, C-2, C11, and C-12, and therefore exhibited lower reactivity to the initiator tert-butyl peroxide. While dispersants C-4 and C-8 showed low wt% tert-butyl peroxide hydroxide loss, the polymerization results in the above polymerization examples indicated that dispersants C-4 and C-8 provided ineffective stability for the fluoropolymer dispersion. C-12 showed a large loss, which is attributed to the presence of phenolic hydroxyl groups in the compound. Phenolic hydroxyl groups are considered susceptible to free radical attack by initiators such as tert-butyl peroxide.

Claims

1. A method for polymerizing at least one fluorinated monomer in an aqueous medium containing an initiator and a hydrocarbon dispersant to form an aqueous dispersion of fluorinated polymer particles, said hydrocarbon dispersant comprising a compound of formula I: R - (XZ) n I Wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups, the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in the one or more aliphatic groups is at least 70%, and the hydrophobic moiety does not contain siloxane units; Each X can be the same or different and represents the hydrophilic part of the ion; Each Z can be the same or different and represents one or more counter ions of the hydrophilic portion of the ion; Where n is between 1 and 3; The hydrophobic hydrocarbon portion of the hydrocarbon dispersant contains at least one aromatic group, and the hydrocarbon dispersant has a molecular weight of at least 215 g / mol in the absence of the counterion Z; and The hydrophilic portion and counterion XZ are of formula -A - - Y + The group, wherein A - It is a carboxylate or sulfonate group; and where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

2. The method according to claim 1, wherein (i) The hydrophobic hydrocarbon moiety comprises no more than three consecutive CH2 groups; and / or (ii) The hydrophobic hydrocarbon portion contains at least three CH3 groups.

3. The method according to any one of claims 1 to 2, wherein A - It is a sulfonate group.

4. The method according to any one of claims 1 to 2, wherein the one or more aliphatic groups in the hydrophobic hydrocarbon portion are acyclic or cyclic alkyl groups.

5. The method according to any one of claims 1 to 2, wherein the hydrophobic hydrocarbon portion comprises one or more aromatic groups. in: (i) The one or more aromatic groups are substituted and have a Hammett σ+ value greater than -1.

0. (ii) The hydrophobic hydrocarbon portion does not contain methyl groups that are directly bonded to aromatic groups. (iii) The hydrophobic hydrocarbon portion does not contain benzyl hydrogen atoms, and / or (iv) The hydrophobic hydrocarbon portion does not contain phenolic hydroxyl groups.

6. The method according to any one of claims 1 to 2, wherein the hydrophobic hydrocarbon portion comprises 8 to 50 carbon atoms.

7. The method according to any one of claims 1 to 2, wherein the hydrophobic hydrocarbon moiety is free of carbon-hydrogen bonds, the carbon-hydrogen bonds having a bond dissociation energy that generates a hydrocarbon radical of less than 100 kcal / mol.

8. The method according to any one of claims 1 to 2, wherein the hydrocarbon dispersant has a loss of less than 10% by weight of tert-butyl peroxide.

9. The method according to any one of claims 1 to 2, wherein the hydrocarbon dispersant comprises a substituted portion of the following formula: Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal.

10. The method according to claim 1, wherein the hydrocarbon dispersant is a compound of formula II: Where R 2' and R 2'' They are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 2' and R 2'' The percentage of the total number of CH3, CH2, and CH groups in the group is at least 70%, or R 2' and R 2'' They can be joined together to form a saturated or unsaturated aliphatic ring that can contain ether or ester bonds, provided that the percentage of total CH3 groups relative to the total number of CH3, CH2 and CH groups in the ring is at least 70%; Where R 1 It is hydrogen, methoxy, ethoxy, or phenoxy; and Where Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal. in: (i) In the compounds of formula II, R 2' and R 2'' It is the same or different and is tert-butyl, tert-butoxy, 2,3,3-trimethyl-2-butyl, or 2,3,3-trimethyl-2-butoxy or -CO(O)C(CH3)3, and wherein R 1 It is hydrogen or methoxy, and where Y is hydrogen or methoxy. + It is hydrogen, ammonium or alkali metal, (ii) In the compounds of formula II, R 2' and R 2'' They are the same or different and are tert-butyl or 2,3,3-trimethyl-2-butyl, R 1 It is hydrogen, and Y + It is hydrogen, ammonium or alkali metal, (iii) In the compounds of formula II, R 2 'and R 2 '' is the same or different and is tert-butyl or 2,3,3-trimethyl-2-butyl, R 1 It is methoxy, and Y + It is hydrogen, ammonium or alkali metal, or (iv) In the compounds of formula II, R 2 'and R 2 '' are all tert-butyl, R 1 It is hydrogen or methoxy, and Y + It is hydrogen, ammonium, or an alkali metal.

11. The method of claim 10, wherein the fluoropolymer comprises a TFE / PMVE fluoroelastomer copolymer, and wherein the hydrocarbon dispersant of formula II is , where Y + It can be hydrogen, ammonium, or alkali metal.

12. The method according to claim 1, wherein the hydrocarbon dispersant is a compound of formula III: Where R 3 R 4' and R 4'' They are the same or different and are hydrogen or saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms, wherein the total CH3 groups are relative to said R 3 R 4' and R 4'' The percentage of the total number of CH3, CH2, and CH groups in the group is at least 70%, provided that R 3 R 4' and R 4'' At least one of them is not hydrogen, and when R 4' and R 4'' When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4' and R 4'' Not hydrogen, and Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal. in: (i) In the compounds of Formula III, R 3 R 4' and R 4'' They are the same or different and are hydrogen, tert-butyl, tert-butoxy, 2,3,3-trimethyl-2-butyl, or 2,3,3-trimethyl-2-butoxy, provided that R 3 R 4' and R 4'' At least one of them is not hydrogen, and when R 4' and R 4'' When it is hydrogen, R 3 Not hydrogen, and when R 3 When it is hydrogen, R 4' and R 4'' Not hydrogen, and Y + It can be hydrogen, ammonium, quaternary ammonium, nitrogen heterocyclic, alkali metal or alkaline earth metal. (ii) In the compounds of Formula III, R 3 It is tert-butyl or 2,3,3-trimethyl-2-butyl, R 4 'and R 4 '' is hydrogen, and Y + It is hydrogen, ammonium or alkali metal, (iii) In the compounds of formula III, R 3 It is tert-butyl, and R 4 'and R 4 '' is hydrogen, and Y + It is hydrogen, ammonium or alkali metal, (iv) In the compounds of Formula III, R 4 'and R 4 '' is the same or different and is tert-butyl or 2,3,3-trimethyl-2-butyl, R 3 It is hydrogen, and Y + It is hydrogen, ammonium or alkali metal, or (v) In the compounds of Formula III, R 4 'and R 4 '' is tert-butyl, R 3 It is hydrogen, and Y + It is hydrogen, ammonium, or an alkali metal.

13. The method according to any one of claims 1 to 2, wherein the initiator contained in the aqueous medium is an organic peroxide.

Images