Process for preparing fluoropolymers and fluoroelastomers in the presence of non-fluorinated sulfonate-type hydrocarbon-containing surfactants - Patents.com

Abstract

The present invention relates to a method for preparing a fluoropolymer or fluoroelastomer in an aqueous medium using a non-fluorinated sulfonate-type hydrocarbon-containing surfactant, the method comprising the steps of: (a) forming an aqueous solution containing a non-fluorinated hydrocarbon-containing sulfonate anionic surfactant in a polymerization reactor; (b) pressurizing the reactor with a fluoromonomer to form an aqueous emulsion; (c) initiating polymerization of the fluoromonomer; (d) propagating the reaction; and (e) terminating the reaction after a desired amount of fluoromonomer is consumed, wherein the non-fluorinated hydrocarbon-containing sulfonate-type surfactant contains 18 to 36 carbon atoms and the molecular weight of the fluoropolymer is 1×10 3 ~9×10 8 g / mol range, and the method does not involve deactivation of the surfactant.

Description

[Technical field]

[0001] The present invention relates to a process for polymerizing fluoromonomers in the presence of non-fluorinated surfactants for the production of fluoropolymers and fluoroelastomers using emulsion polymerization techniques. More specifically, the present invention relates to a process for aqueous dispersion polymerization in the presence of non-fluorinated sulfonate-type hydrocarbon-containing surfactants. [Background technology]

[0002] Fluoropolymers and fluoroelastomers represent a class of materials that exhibit extremely high chemical resistance and favorable dielectric properties. As a result, there is an ever-increasing demand for these materials from industries involved in the production of coatings, tapes and tubing, architectural fabrics, non-stick and industrial coatings, fluoroelastomer hoses for the automotive industry, and seals, gaskets and liners, insulated wire and cable, lubricants, etc. for the chemical industry. This ever-increasing demand, in turn, is driving renewed interest in the development of environmentally friendly and more efficient routes to produce fluoropolymers and fluoroelastomers. Fluoropolymers and fluoroelastomers are typically synthesized from alkenes in which one or more hydrogen atoms are replaced with fluorine atoms. Such alkenes include tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), polypropyl vinyl ether (PPVE), polymethyl vinyl ether (PMVE), vinylidene fluoride (VDF), vinyl fluoride (VF), etc. Polymerization of the above monomers can give the corresponding polymers, namely, polytetrafluoroethylene (PTFE), perfluoroalkoxyether (PFA) polymers, fluorinated ethylene propylene (FEP) polymers, polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), fluoroelastomers, etc.

[0003] Fluoropolymers and fluoroelastomers are primarily produced by heterogeneous polymerization reactions involving aqueous systems. Generally, this reaction requires monomers and radical initiators in a suitable aqueous reaction medium. Aqueous dispersion polymerization of fluorine-containing monomers typically requires a surfactant that can emulsify both reactants and reaction products for the duration of the polymerization reaction. As discussed below, the surfactants selected in the synthesis of fluoropolymers and fluoroelastomers are generally fully fluorinated or partially fluorinated surfactants. The fully fluorinated surfactants most frequently used in the production of fluoropolymers and fluoroelastomers are perfluorooctanoic acid (PFOA) salts.

[0004] Perfluorosurfactants are better at reducing the surface tension of water than comparable hydrocarbon surfactants, but fluorinated surfactants persist in the environment for longer periods and have been detected in humans and wildlife. REACH Annex XVII, Entry 68 by the European Chemicals Agency restricts the placing on the market and use of certain hazardous substances, mixtures and articles containing perfluorooctanoic acid (PFOA) and its salts. In addition, according to the document, there are restrictions on any related substances (including their salts and polymers) that have as one of their structural elements a linear or branched perfluoroheptyl group of formula C7F15- directly bonded to another carbon atom. The use of any related substances (including their salts and polymers) that have as one of their structural elements a linear or branched perfluorooctyl group of formula C8F17- is also restricted. According to the document, as of July 4, 2020, the above substances may not be manufactured or placed on the market. Furthermore, the above substances, at concentrations above 25 ppb for PFOA and its salts and above 1000 ppb for one or a combination of PFOA-related substances, are prohibited from being used or placed on the market (a) as constituents in the manufacture of other substances; (b) in the manufacture of mixtures; and (c) in the manufacture of articles. Therefore, taking into account the European Chemicals Agency's REACH 2020 guidelines, a method for the polymerization of fluoromonomers without the use of fluorinated surfactants is needed.

[0005] In the prior art, Patent Document 1 provides a method for forming an aqueous medium dispersion of fluoropolymer particles by polymerizing fluoromonomer in a polymerization reactor, comprising: (a) providing an aqueous medium in the reactor; (b) adding fluoromonomer to the reactor; (c) adding an initiator to the aqueous medium; (the combination of steps (b) and (c) is essentially carried out without a hydrocarbon-containing surfactant, and results in the kickoff of polymerization of fluoromonomer); and (d) metering a hydrocarbon-containing surfactant into the aqueous medium after the polymerization is started, for example, after the concentration of fluoropolymer in the aqueous medium is at least 0.6% by weight, said metering is at a rate that reduces the telogen activity of the surfactant while maintaining the surface activity.

[0006] Patent Document 2 discloses a method for producing a fluoropolymer that can reduce the content of impurities. The present invention is a method for producing a fluoropolymer, which is characterized by including a polymerization step of obtaining a fluoropolymer by carrying out polymerization of a fluoromonomer in an aqueous medium in the presence of a surfactant, and further characterized in that the surfactant is a carboxylic acid type hydrocarbon-containing surfactant.

[0007] The method of polymerizing fluoromonomers and fluoroelastomers using non-fluorinated surfactants is believed to solve the above-mentioned problems of the persistence in ecosystems and bioaccumulation of fluorosurfactants. However, the use of non-fluorinated surfactants in the polymerization reaction leads to inhibition of the reaction and the production of low molecular weight fluoropolymers.

[0008] It is essential to decompose the non-fluorinated surfactant before the start of the polymerization reaction to prevent inhibition of the polymerization. Decomposition of the surfactant using a suitable decomposition agent leads to the reduction or elimination of telogenity, which essentially leads to inhibition of the polymerization reaction.

[0009] A facile polymerization process that does not require the use of decomposing agents to deactivate the surfactant is highly desirable to reduce the cost, time and complexity of the polymerization process.

[0010] Due to the existence of carboxylic acid type surfactants and other types of surfactants in the prior art, there was a need to establish the use of non-fluorinated sulfonate type hydrocarbon-containing surfactants in fluoropolymerization processes.

[0011] Additionally, there is a need for methods of preparing fluoropolymers and fluoroelastomers having low to high molecular weights using non-fluorinated surfactants that do not result in surfactant deactivation. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent No. 9,255,164 [Patent Document 2] International Publication No. 2019172382 Summary of the Invention [Problem to be solved by the invention]

[0013] The main object of the present invention is to overcome the above problems in the prior art. Another object of the present invention is to provide a method for aqueous dispersion polymerization of fluoromonomers and fluoroelastomers using non-fluorinated surfactants.

[0014] It is yet another object of the present invention to provide a process for the aqueous dispersion polymerization of monomers such as tetrafluoroethylene using non-fluorinated hydrocarbon-containing sulfonate-type surfactants.

[0015] Yet another object of the present invention is to provide a simple, one-step process for preparing fluoropolymers and fluoroelastomers.

[0016] Another object of the present invention is to provide a process for preparing fluoropolymers and fluoroelastomers that does not include a surfactant deactivation step.

[0017] Another object of the present invention is to provide a process for preparing fluoropolymers and fluoroelastomers of optimal particle size.

[0018] It is yet another object of the present invention to provide fluoropolymer and fluoroelastomer dispersions containing non-fluorinated hydrocarbon-containing sulfonate type surfactants.

[0019] It is yet another object of the present invention to produce low to high molecular weight fluoropolymers using non-fluorinated surfactants.

[0020] Another object of the present invention is to provide a fluoropolymer resin obtained by aqueous polymerization using a non-fluorinated hydrocarbon-containing sulfonate type surfactant. [Means for solving the problem]

[0021] According to one aspect of the present invention, The fluoromonomer is reacted with the fluoromonomer in the presence of a surfactant. aqueous dispersion medium Among them, fluoropolymer and / or polymerized into fluoroelastomers 1. A method for producing a pharmaceutical composition comprising the steps of: The above The surfactant is a non-fluorinated hydrocarbon-containing sulfonate surfactant represented by formula (1), R l -[Ar 2 X 1 ]-(SO 3 M + ) m (1) During the ceremony: R is an alkyl group containing 2 to 20 carbon atoms; l is the number of alkyl groups, 1 OR 2 and; Ar is an aryl group; X is a bridge between the aryl groups Ar, said bridge being CH 2 or ether or amine N Bonding by either -C 2 H 4 -(N-(C 2 H 5 ))-C 2 H 4 -or-C 2 H 4 -(N-(C 2 H 4 -)-C 2 H 4 - or a carbonyl group (C=O), M + is hydrogen, alkali metals, NH 4 + or a combination thereof; and m is an integer ranging from 1 to 2. What? , (a) forming an aqueous solution comprising the surfactant in a polymerization reactor; (b) pressurizing the polymerization reactor with fluoromonomer to form an aqueous dispersion; (c) initiating the polymerization reaction of the fluoromonomer by adding an initiator to the polymerization reactor; (d) propagating the polymerization reaction to grow the chain length of the fluoropolymer and / or fluoroelastomer; (e) terminating the polymerization reaction after a desired amount of fluoromonomer has been consumed; Including, The surfactant is metered into the polymerization reactor at a predetermined rate during the polymerization reaction. A method is provided. [Brief description of the drawings]

[0022] [Figure 1] 1 is a flow chart of a method of preparing a fluoropolymer in an aqueous dispersion using a non-fluorinated hydrocarbon-containing sulfonate type surfactant according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] For the purposes of promoting and understanding the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same, but no limitation of the scope of the invention is intended by said description, it being understood that alterations and further modifications in the illustrated system, and further applications of the principles of the invention as illustrated, will occur to those skilled in the art to which the invention pertains.

[0024] Several representative embodiments of the present invention are discussed below. The invention in its broader aspects is not limited to the specific details and representative methods. Illustrative examples are described in this section in connection with the embodiments and methods provided.

[0025] It should be noted that as used herein, the singular forms "a," "a," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds. It should also be noted that the term "or" is typically used in the sense of including "and / or" unless the context clearly dictates otherwise.

[0026] The various quantity expressions relating to "%" or "% w / w" mean percentage by weight of the total solution or composition, unless otherwise specified.

[0027] All cited references are incorporated herein by reference in their entirety. The citation of any reference is not an admission regarding its availability as prior art to the claimed invention.

[0028] It is to be understood that the foregoing general description and the following detailed description are illustrative of the invention but are not intended to be restrictive of the invention.

[0029] Throughout this specification, reference to phrases such as "in one aspect," "in another aspect," and the like means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Thus, phrases such as "in one embodiment," "in another embodiment," and the like, throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0030] The terms "comprise", "comprising", or any other variation thereof, are intended to mean that a method or process that includes a list of steps not only includes those steps, but also covers steps not expressly listed or inherent in such method or process.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The systems, methods, and examples described herein are illustrative only and are not intended to be limiting.

[0032] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0033] The present invention in all its aspects is described in detail below.

[0034] The present invention relates to a process for preparing high molecular weight fluoropolymers using non-fluorinated disulfonate-type hydrocarbon-containing surfactants. More specifically, the present invention relates to a process for aqueous dispersion polymerization using non-fluorinated hydrocarbon-containing sulfonate-type surfactants.

[0035] As mentioned above, perfluoroalkylated substances (PFAS) such as fully fluorinated surfactants, e.g., PFOA, are prohibited by the European Chemicals Agency's REACH2020 guidelines. On the other hand, non-fluorinated surfactants inhibit the polymerization reaction and produce low molecular weight fluoropolymers, so they require surfactant inactivation using a decomposition agent. In consideration of the above problems, the inventors of the present invention have In aqueous media A new method for preparing low to high molecular weight fluoromonomers has been developed. The method comprises the steps of: a) forming an aqueous solution comprising a surfactant in a polymerization reactor; b) pressurizing the polymerization reactor with the fluoromonomer to form an aqueous dispersion; c) initiating the polymerization reaction of the fluoromonomer by adding an initiator to the polymerization reactor; d) propagating the polymerization reaction for chain length growth of the fluoropolymer and / or fluoroelastomer; e) terminating the polymerization reaction after the desired amount of fluoromonomer has been consumed; Including, The non-fluorinated hydrocarbon-containing sulfonate surfactant contains 18 to 33 carbon atoms. Here, the molecular weight of the fluoropolymer is 1×10 3 ~9× 10 8 g / mol range and the method does not include surfactant deactivation.

[0036] The aqueous emulsion formed in the present invention comprises a surfactant, a fluoromonomer, an initiator, and paraffin wax, Nucleating Agents and Reducing Agents Stabilizers such as may include.

[0037] Surfactants The term "surfactant" refers to a type of molecule that has both hydrophobic and hydrophilic portions, which allows for the stabilization and dispersion of hydrophobic molecules in aqueous systems, as well as the aggregation of hydrophobic molecules. A group of surfactants that are preferred for fluoropolymer and fluoroelastomer synthesis according to embodiments of the present invention includes non-fluorinated hydrocarbon-containing sulfonate type surfactants, more preferably non-fluorinated hydrocarbon-containing anionic sulfonate type surfactants. In one embodiment, the non-fluorinated hydrocarbon-containing anionic sulfonate type surfactant can be an alkyldiphenyloxide anionic surfactant.

[0038] In one embodiment, the surfactant is a non-fluorinated hydrocarbon-containing sulfonate surfactant represented by formula (1): R l -[Ar 2 X]-(SO 3 M+ ) m (1) During the ceremony: R is an alkyl group containing 2 to 20 carbon atoms; l is The number of alkyl groups is 1. ; Ar is an aryl group ; X is a bridge between the aryl groups Ar, said bridge being CH 2 or Ether Ru Waka or amines function Either join or -C 2 H 4 -(N-(C 2 H 5 ))-C 2 H 4 -or-C 2 H 4 -(N-(C 2 H 4 -)-C 2 H 4 - or a carbonyl group (C=O), M + is hydrogen, alkali metals, NH 4 + or a combination thereof; and m is an integer ranging from 1 to 2.

[0039] In one embodiment, A process is provided for polymerizing fluoromonomers into fluoropolymers and / or fluoroelastomers in an aqueous dispersion in the presence of a surfactant. The surfactant is for example Formula with 28 carbon atoms (2) where R is an alkyl group and M is a monovalent cation selected from the group consisting of hydrogen ions, alkali metal ions, and ammonium ions. Preferably, R may be a branched or straight chain alkyl group. Preferably, M is selected from the group consisting of potassium, sodium and ammonium.

[0040] [ka]

[0041] In a preferred embodiment, the anionic surfactant is in the form of an acid or its salt. The anionic surfactant has a counter anion M. Preferably, M can be potassium, sodium or ammonium. Examples of fluorinated surfactants useful in the present invention include the ammonium or potassium or sodium salts of the acids of formula 1.

[0042] In this method, An example of a non-fluorinated hydrocarbon-containing sulfonate surfactant is 、 formula In the example below, It can be expressed as [ka]

[0043] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0044] In a preferred embodiment, the surfactant can be represented by formula (3): [ka]

[0045] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0046] In a preferred embodiment, the surfactant for the emulsion polymerization of fluoromonomers according to the method of the present invention is represented by the formula (4) It is expressed as [ka]

[0047] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0048] In the process of the present invention, a co-surfactant may be used in conjunction with the above surfactants.

[0049] In one embodiment, the non-fluorinated hydrocarbon-containing sulfonate surfactant has the formula: (5) and [ka]

[0050] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0051] In one embodiment, the non-fluorinated hydrocarbon-containing sulfonate surfactant has the formula: (6) It may also have. [ka]

[0052] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0053] In another embodiment of the present invention, there is provided a process for polymerizing fluoromonomers into fluoropolymers and / or fluoroelastomers in an aqueous dispersion in the presence of a surfactant represented by formula (7), [ka]

[0054] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0055] In another embodiment of the present invention, there is provided a process for polymerizing fluoromonomers into fluoropolymers and / or fluoroelastomers in an aqueous dispersion in the presence of a surfactant represented by formula (8), [ka]

[0056] In the formula, R is an alkyl group containing 2 to 20 carbon atoms.

[0057] The surfactant is added to the reactor all at once or is metered into the polymerization reactor at a predetermined rate during the propagation of the polymerization reaction.

[0058] Fluoromonomers The term "fluoromonomer" or "fluorinated monomer" refers to a polymerizable alkene having at least one fluorine atom, fluoroalkyl group, or fluoroalkoxy group attached to the double bond of the alkene undergoing polymerization. The terms "fluoropolymer" and fluoroelastomer refer to a polymer or elastomer formed by polymerization of at least one fluoromonomer, including homopolymers, copolymers, terpolymers, and higher polymers. Examples of fluoromonomers that can be used in the present invention include, but are not limited to, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), polypropylvinylether (PPVE), polymethylvinylether (PMVE), chlorotrifluoroethylene (CTFE), vinylidene fluoride (VDF), vinyl fluoride (VF), and the like, each of which can be used individually or in combination. Preferably, the fluoromonomer is tetrafluoroethylene (TFE) and the fluoropolymer is polytetrafluoroethylene (PTFE). Although embodiments of the present invention are described with respect to the polymerization of TFE, the methods described herein can be applied to the polymerization of any fluoromonomer.

[0059] The aqueous emulsion may further include an initiator for initiating the polymerization process.

[0060] Initiator The terms "initiator" and "radical initiator" and "free radical initiator" refer to chemicals that can provide a source of free radicals either by spontaneous induction or by exposure to heat or light. Examples of suitable initiators include peroxides, peroxydicarbonates, and azo compounds. Initiators can also include reduction-oxidation systems that provide a source of free radicals. The terms "radical" and "free radical" refer to chemical species that contain at least one unpaired electron. The radical initiator is added to the reaction mixture in an amount sufficient to initiate and sustain the polymerization reaction rate. The radical initiator can include a persulfate, such as sodium persulfate, potassium persulfate, or ammonium persulfate. Alternatively, the radical initiator can include a redox system. It will be understood by those skilled in the art that a "redox system" refers to a system that includes an oxidizing agent, a reducing agent, and optionally a promoter as an electron transfer medium. In a preferred embodiment, the radical initiator is J The initiator is selected from the group consisting of diphenyl diphenyl ether (DSAP), ammonium persulfate (APS), redox initiators, and combinations thereof.

[0061] Chain Transfer Agents Chain transfer agents, also called regulators or moderators, contain at least one chemically weak bond. Chain transfer agents react with free radical sites on growing polymer chains, terminating the chain extension. Chain transfer agents are often added during emulsion polymerization to control the chain length of the polymer to achieve desired properties in the polymer. Examples of chain transfer agents that can be used in the present invention include, but are not limited to, halogen compounds, general hydrocarbons, aromatic hydrocarbons, thiols (mercaptans), alcohols, and the like, each of which can be used individually or in combination.

[0062] Nucleating Agent Nucleating agents represent another important component used in emulsion polymerization of fluoromonomers. The use of nucleating agents creates a large number of free radical sites that are distributed in the polymerization reactor. These large number of free radical sites counteract the telogenic or inhibitory effect of non-fluorinated surfactants on polymerization. In general, non-fluorinated surfactants essentially inhibit free radical sites from further reacting or participating in the polymerization reaction by telogenicity. The addition of nucleating agents promotes polymerization even at low initiator concentrations. In simple terms, nucleating agents reduce the inhibitory effect of non-fluorinated surfactants on the polymerization rate, resulting in lower initiator consumption and higher molecular weight fluoropolymers. The term "nucleating agent" as used in the present invention refers to the combination of non-fluorinated anionic surfactants and redox systems (including oxidizing agents such as ammonium persulfate, potassium persulfate, and potassium permanganate, and reducing agents such as sodium sulfite, sodium bisulfite, and oxalic acid).

[0063] Reducing Agent As mentioned above, the reducing agent forms part of the nucleating agent and counters the telogenic effect of the non-fluorinated surfactant on the polymerization process. The reducing agent works with an oxidizing agent, such as ammonium persulfate, to generate free radicals at very low to high reaction temperatures to promote the polymerization reaction. Examples of reducing agents useful in the present invention include, but are not limited to, sodium sulfite, sodium bisulfite, sodium acetate, oxalic acid, and the like, each of which may be used independently or in combination.

[0064] Polymerization conditions The temperature used for the polymerization can vary, for example, from 20 to 120° C., depending on the initiator system selected and the reactivity of the fluoromonomer selected. In a preferred embodiment, the polymerization is carried out at a temperature in the range of 65 to 110° C.

[0065] The pressure used for the polymerization can vary from 2 to 200 bar, depending on the choice of reactor, initiator system and monomers. In a preferred embodiment, the reaction is carried out at a pressure in the range of 10 to 60 bar.

[0066] The polymerization occurs under stirring or agitation. The stirring can be constant or can be varied during the course of the polymerization to optimize process conditions. In one embodiment, both multiple stirring speeds and multiple temperatures are used to control the reaction.

[0067] According to one embodiment of the process of the present invention, a pressurized polymerization reactor equipped with stirring and heat control means is charged with water (preferably deionized water), a non-fluorinated hydrocarbon-containing sulfonate type surfactant according to the present invention, a nucleating agent, a reducing agent, a chain transfer agent and at least one fluoromonomer.

[0068] Preferably, the hydrocarbon-containing sulfonate surfactant is added in an amount ranging from 40 to 3900 ppm (1 to 100 g), more preferably from 200 to 2000 ppm (5 to 50 g), based on the weight of the fluoropolymer dispersion. Most preferably, the concentration of the surfactant is from 700 to 1200 ppm based on the weight of the fluoropolymer. In a preferred embodiment, the dosing rate of the non-fluorinated hydrocarbon-containing sulfonate surfactant during the polymerization reaction is in the range of 0.008 g / L-hour to 0.6 g / L-hour. Preferably, the reaction mixture contains a chain transfer agent in an amount ranging from 100 to 4500 ppm (0.5 to 40 g). The mixture may optionally contain paraffin wax. The reactor is then heated to the reaction temperature and pressurized. An initiator is then added to the reaction vessel to initiate the polymerization reaction. Preferably, the initiator is added in an amount ranging from 2 to 1500 ppm based on the weight of the deionized water. Before introducing the surfactant and one or more monomers into the reaction vessel to initiate the reaction, it is preferred to remove air from the reactor to obtain an oxygen-free environment for the polymerization reaction. Preferably, oxygen is removed from the reaction vessel until its concentration is less than 10 ppm. The reactor may be purged with a neutral gas, such as nitrogen or argon.

[0069] Once the polymerization reaction is complete, the reactor is brought to ambient temperature and the remaining unreacted monomers are vented to atmospheric pressure. The aqueous reaction medium containing the fluoropolymer is then recovered from the reaction vessel. Preferably, the solids content is between 10 and 65%, more preferably 20 to 35%, more preferablyThe content is in the range of 20 to 25%, and the particle size of the fluoropolymer particles is preferably in the range of 50 to 300 nm.

[0070] The present invention is more particularly described in the following examples, which are intended to be illustrative only, since numerous modifications and variations within the scope of the invention will be apparent to those skilled in the art. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples were obtained or are available from commercial chemical suppliers.

[0071] The following examples illustrate the basic methodology and versatility of the present invention. EXAMPLES

[0072] The polymerization process was carried out in a 150 L polymerization reactor containing 60-130 L of deionized water. A nucleating agent, which is a combination of a surfactant and a redox system, was added to the polymerization reactor in an amount of 3-200 ppm (0.1-5 g). Oxygen was removed from the reactor until the concentration was less than 10 ppm. The reaction mixture was then stirred at 30-70 rpm and 50-1000 mL of ammonium persulfate (APS) solution (0.5 g / L) was added to obtain a concentration of 0.4-200 ppm (0.01-5 g).

[0073] The pressure in the polymerization reactor was then increased to 15-60 bar by adding tetrafluoroethylene monomer. Then, 0.01-5 g of non-fluorinated alkyl diphenyl oxide was added. Sulfonate typeThe surfactant was added. A mixture of 0-450 ppm (0-30 g) ammonium persulfate (APS) and 0-6000 ppm (0-400 g) disuccinic acid peroxide (DSAP) was added to the polymerization reactor to start the reaction. The reaction temperature was maintained in the range of 65-110 °C and the pressure was maintained in the range of 10-60 bar. A pressure drop in the range of 0.1-2 bar (which corresponds to a consumption of 0.1-3 kg TFE) indicates the start of the reaction. After the start of the reaction, the metering of the surfactant solution was carried out at a rate of 1-100 mL / min. The concentration of the surfactant solution was in the range of 5-5000 ppm (0.0005-5%). The non-fluorinated alkyl diphenyl oxy group in the reaction mixture was 0.0005-5%. Disulfonate type The total amount of surfactant ranged from 40 to 8400 ppm (1 to 200 g) based on the weight of the fluoropolymer.

[0074] The polymerization reaction lasted for a time ranging from 20 to 700 min, during which 10 to 45 kg of TFE was consumed, resulting in the formation of tetrahydrofuran with particle sizes ranging from 50 to 300 nm and molecular weights of 2 × 10 5 ~9×10 8 PTFE particles were obtained in the g / mol range with solid contents ranging from 10 to 65%.

[0075] In order to practice and demonstrate the present invention, various experiments described below were performed.

[0076] Test 1: This includes experiments with delayed addition of a hydrocarbon surfactant and its metering into the polymerization reactor, as well as the improvements obtained when a dispersion of lipophilic nucleation sites is generated before the start of the polymerization reaction, in the presence or absence of salt. General procedure for polymerizations without a nucleation site generation step before the start of the polymerization: To a 150 L (liter) horizontal jacketed stainless steel reactor equipped with a 6-blade agitator, 70 liters of deionized degassed water and 3 kg of liquid wax were added. The reactor was sealed and placed under vacuum until the oxygen level reached less than 10 ppm. The reactor pressure was reduced to 1 kg / cm with nitrogen. 2 (103.2 kPa) and vacuum were applied five times. The reactor agitator was set at 50 rpm.

[0077] After the vacuum nitrogen cycle, 0.27 gm of non-fluorinated surfactant and 0.5 gm of sodium sulfite, followed by 0.27 gm of ammonium persulfate (APS) were added to the reactor and then pressurized. The reactor was then heated to 90° C. and TFE was charged to the reactor to bring the reactor pressure to 24 kg / cm. 2 At time zero, 500 mL of a deionized, degassed initiator solution in water containing 0.938 g ammonium persulfate (APS) and 36 g disuccinic acid peroxide (DSAP) was injected at 200 mL / min.

[0078] TFE at a pressure of 24kg / cm 2 The reactor was filled to 2.35 MPa (2.35 MPa) and this pressure was maintained throughout the polymerization. After 1.3 kg of TFE had been fed since initiation, the stabilizer surfactant solution was pumped into the reactor at a rate of 15 mL / min, which corresponds to a surfactant feed rate of 0.06 g / L at 200°C.

[0079] After 24 kg of TFE had been added to the reactor since start, the batch time (Table A) was recorded, the agitator was stopped, the reactor was vented to atmospheric pressure, and the dispersion was drained. Upon cooling, the wax separated from the dispersion.

[0080] Examples 2-3: In these experiments, polymerizations were carried out with delayed addition of the hydrocarbon surfactant, its metering into the polymerization reactor, and the improvements obtained when a dispersion of lipophilic nucleation sites was generated before the start of the polymerization reaction, with or without salt. The general procedure for polymerizations without a step of generating nucleation sites before the start of the polymerization was carried out: 70 liters of deionized, degassed water and 3 kg of liquid wax were added to a 150 liter horizontal jacketed stainless steel reactor equipped with a 6-blade agitator. The reactor was sealed and placed under vacuum until the oxygen level reached 10 ppm. The reactor pressure was reduced to 1 kg / cm with nitrogen. 2 (103.2 kPa) and vacuum were applied five times. The reactor agitator was set at 50 rpm.

[0081] After the vacuum nitrogen cycle, 0.27 gm of non-fluorinated surfactant and 0.5 gm of sodium sulfite were added to the reactor followed by 0.27 gm of ammonium persulfate (APS) and then pressurized. The reactor was heated to 90°C and TFE was charged to the reactor to bring the reactor pressure to 24 kg / cm. 2 (2.35 MPa). At time zero, 500 mL of a deionized, degassed aqueous solution of initiator containing 36 g of disuccinic acid peroxide (DSAP) was injected at 200 mL / min. TFE was pumped at a pressure of 24 kg / cm. 2 The reactor was filled to a pressure of (2.35 MPa) and this pressure was maintained throughout the polymerization.

[0082] After 1.3 kg of TFE have been fed since start-up, the stabilizer surfactant solution is pumped into the reactor at a rate of 15 mL / min. This corresponds to a surfactant feed rate of 0.06 g / L at 20°C. After 24 kg of TFE have been added to the reactor since start-up, the batch time (Table A) is recorded, the agitator is stopped, the reactor is vented to atmospheric pressure, and the dispersion is discharged. Upon cooling, the wax separates from the dispersion.

[0083] Test 4: The experiments include polymerizations with delayed addition of a hydrocarbon surfactant and its metering into the polymerization reactor, as well as the improvements obtained when a dispersion of lipophilic nucleation sites is generated prior to the start of the polymerization reaction, in the presence or absence of salt.

[0084] General procedure for polymerizations without a nucleation site generation step prior to initiation of polymerization: 70 liters of deionized and degassed water and 3 kg of liquid wax were added to a 150 liter horizontal jacketed stainless steel reactor equipped with a 6-blade agitator. The reactor was sealed and placed under vacuum until the oxygen level reached less than 10 ppm. The reactor pressure was reduced to 1 kg / cm with nitrogen. 2 (103.2 kPa) and vacuum were performed five times. The reactor agitator was set at 50 rpm. The reactor was heated to 90° C. and TFE was charged to the reactor to bring the reactor pressure to 24 kg / cm. 2 (2.35MPa).

[0085] At time zero, 500 mL of a deionized, degassed aqueous solution of initiator containing 36 g of disuccinic acid peroxide (DSAP) was injected at 200 mL / min. TFE was pumped at a pressure of 24 kg / cm 2 The reactor was filled to a pressure of (2.35 MPa) and this pressure was maintained throughout the polymerization.

[0086] After 0.5 kg of TFE had been fed since start, the stabilizer surfactant solution was pumped into the reactor at a rate of 15 mL / min, which corresponds to a surfactant feed rate of 0.06 g / L at 20°C. After 24 kg of TFE had been added to the reactor since start, the batch time (Table A) was recorded, the agitator was stopped, the reactor was vented to atmospheric pressure, and the dispersion was discharged. Upon cooling, the wax separated from the dispersion.

[0087] Tests 6-7: These experiments include polymerizations with delayed addition of a hydrocarbon surfactant and its metering into the polymerization reactor, as well as the improvements obtained when a dispersion of lipophilic nucleation sites is generated prior to the start of the polymerization reaction, in the presence or absence of salt. General procedure for polymerizations without a nucleation site generation step prior to the start of polymerization: 70 L (liters) of deionized, degassed water and 3 kg of liquid wax were added to a 150 liter horizontal jacketed stainless steel reactor equipped with a 6-blade agitator. The reactor was sealed and placed under vacuum until the oxygen level reached less than 10 ppm.

[0088] The reactor pressure was adjusted to 1 kg / cm using nitrogen. 2 (103.2 kPa) and vacuum cycles were performed 5 times. The reactor agitator was set at 50 rpm. After the vacuum nitrogen cycle, 5 gm of non-fluorinated surfactant was added to the reactor and then pressurized. The reactor was heated to 90° C. and TFE was charged to the reactor to bring the reactor pressure to 24 kg / cm. 2 (2.35MPa).

[0089] At time zero, 1000 mL of a deionized, deaerated aqueous solution of initiator containing 6-7 g ammonium persulfate (APS) and 40-46.5 g disuccinic acid peroxide (DSAP) was injected at 250 mL / min. TFE was pumped at a pressure of 24 kg / cm. 2 The reactor was filled to a pressure of (2.35 MPa) and this pressure was maintained throughout the polymerization.

[0090] After 3-3.5 kg of TFE had been fed since start, the stabilizer surfactant solution was pumped into the reactor at a rate of 15 mL / min. This corresponds to a surfactant feed rate of 0.06 g / L at 200°C. After 24 kg of TFE had been added to the reactor since start, the batch time (Table A) was recorded, the agitator was stopped, the reactor was vented to atmospheric pressure, and the dispersion was discharged. Upon cooling, the wax separated from the dispersion.

[0091] [Table 1]

[0092] Various properties of the present invention can be measured using the following methods: 1)Latex particle size Latex particle size can be measured to determine the particle size of dispersed systems with diameters from sub-nanometers to several micrometers. Latex particle size can be measured using dynamic light scattering (DLS). The instrument used to determine the particle size of the fluoropolymer dispersion was a HORIBA SZ100 manufactured by HORIBA Scientific. Particle size analysis was performed by dynamic light scattering (DLS). To perform the analysis, a polystyrene cuvette was first flushed with water using a syringe, which was used to dilute the dispersion sample. Here, 0.8 g of the dispersion sample was taken in the cuvette and water was added to make the volume 100 mL. The cuvette with the diluted sample was placed in the instrument chamber for median particle size DV(50) measurement. Latex particle size can be measured using an instrument called a "Malvern zetasizer".

[0093] Additionally, the latex concentration can be measured using a hydrometer.

[0094] 2) Determination of fluoropolymer content: The solids content of the fluoropolymer in the dispersion is calculated using the following formula set out in the ASTM D4441-15 standard:

number

[0095] During the ceremony, WA: weight of aluminum petri dish WB: Weight of aluminum petri dish + fluoropolymer dispersion WC: Weight of fluoropolymer after drying at 105±5℃ WD: fluoropolymer weight after drying the sample at 380±5°C.

[0096] 3) pH - The pH can be measured using a pH meter. The pH of the dispersion can be measured using a SPECTRA LAB ACCUPH-3 device according to the ASTM E70 standard.

[0097] 4) Standard specific gravity (SSG): Standard Specific Gravity (SSG) is a property commonly used to measure the relative molecular weight of polymers used in the PTFE industry. SSG shall be measured according to the procedure described in ASTM D4895. To perform the test, the sample is subjected to a baking-cooling cycle according to the appropriate baking schedule described in ASTM D4895. The SSG of unmodified PTFE is inversely related to its molecular mass.

[0098] 5) ESG (Expanded Specific Gravity) - Expanded specific gravity gives an indication of thermal stability. ESG can be measured by ASTM D4895. To measure ESG, first, fluoropolymer specimens are molded according to ASTM D4895. For ESG, the samples are kept at the bake temperature for a longer time than the bake time measurement for SSG.

[0099] 6) TII (Thermal Instability Index) - The thermal instability index (TII) gives an indication of how well a resin resists decomposition during extended heating at bake temperatures. TII is measured by ASTM D4895. This test method compares the SSG of a resin to its expanded specific gravity. The specimens used to measure ESG are the same as those used to measure SSG, except that their thermal histories are different.

[0100] 7) Pex (Extrusion Pressure) - The extrusion pressure indicates the degree of fibrillation of the fine powder PTFE. Pex can be measured on a Jennings vertical paste extruder, tested according to ASTM D4895.

[0101] 8) DSC (Differential Scanning Calorimetry) - This is used to measure the melting point. DSC is also used to measure the crystallization characteristics. DSC is measured with an instrument called "DSC Q200 TA". The standard used to measure the melting and crystallization of fluoropolymers is ASTM D4591. According to the said standard, an unheated PTFE sample is heated at a specific rate to a temperature above its melting point to study the endothermic characteristics of the polymer sample. The sample is then cooled to a temperature well below the melting point to analyze the exothermic characteristics of the sample.

[0102] 9) Solids Content - Solids content can be measured by ASTM D4441.

[0103] 10) Tensile Strength - indicates the amount of stress a material can withstand. Tensile strength is measured by ASTM D4895.

[0104] 11) Elongation at break - indicates elongation behavior. Elongation at break is measured according to ASTM D4895.

[0105] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. Accordingly, all embodiments of the present invention are to be considered as illustrative and not restrictive.

[0106] The drawings and the above description provide examples of embodiments. Those skilled in the art will understand that one or more of the described elements may be combined into a single functional element. Alternatively, certain elements may be divided into multiple functional elements. Elements of one embodiment may be added to another embodiment. For example, the order of the methods described herein may be changed and are not limited to the manner described herein.

[0107] Furthermore, the operations of any flowchart need not be performed in the order shown, and not all of the operations need necessarily be performed. Also, operations that are not dependent on other operations may be performed in parallel with other operations. The scope of the embodiments is in no way limited to these specific examples. Numerous variations, such as differences in structure, dimensions, and use of materials, whether or not explicitly given in the specification, are possible. The scope of the embodiments is at least as extensive as that given in the following claims.

[0108] Benefits, other advantages, and solutions to problems have been described above with respect to specific embodiments. However, the above benefits, advantages, solutions to problems, and any elements that may cause or make evident any benefit, advantage, or solution to a problem should not be construed as critical, necessary, or essential features or elements of any or all claims.

Claims

1. A process for polymerizing fluoromonomers into fluoropolymers and / or fluoroelastomers in an aqueous dispersion medium in the presence of a surfactant, comprising the steps of: The surfactant is a non-fluorinated hydrocarbon-containing sulfonate surfactant represented by formula (1), R ｌ -[Ar ２ X １ ]-(SO ３ M ＋ ) ｍ (1) During the ceremony: R is an alkyl group containing 2 to 20 carbon atoms; l is the number of alkyl groups and is 1 or 2; Ar is an aryl group; X is a bridge between aryl groups Ar, said bridge being CH ２ or either an ether or amine bond or -C ２ H ４ -(N-(C ２ H ５ ))-C ２ H ４ -or-C ２ H ４ -(N-(C ２ H ４ -)-C ２ H ４ - or a carbonyl group (C=O); M ＋ is hydrogen, alkali metal, NH ４ ＋ or a combination thereof; and m is an integer ranging from 1 to 2, (a) forming an aqueous solution comprising the surfactant in a polymerization reactor; (b) pressurizing the polymerization reactor with fluoromonomer to form an aqueous dispersion; (c) initiating the polymerization reaction of the fluoromonomer by adding an initiator to the polymerization reactor; (d) propagating the polymerization reaction to grow the chain length of the fluoropolymer and / or fluoroelastomer; (e) terminating the polymerization reaction after a desired amount of fluoromonomer has been consumed; Including, The surfactant is metered into the polymerization reactor at a predetermined rate during the polymerization reaction. method.

2. The method of claim 1, wherein the non-fluorinated hydrocarbon-containing sulfonate surfactant contains from 18 to 33 carbon atoms.

3. The fluoropolymer and / or fluoroelastomer is 1×10 ３ ~9×10 ８ 3. The method of claim 1 or 2, wherein the polymer has a molecular weight of about 100 g / mol.

4. The method of any one of claims 1 to 3, which does not include deactivating said detergent.

5. 2. The method of claim 1, wherein the surfactant is metered at a rate of from 0.008 g / L-hr to 0.6 g / L-hr.

6. 6. The method of any one of claims 1 to 5, wherein the initiator for initiating the polymerization reaction is selected from the group consisting of dihydroperoxide succinate (DSAP), ammonium persulfate (APS), redox initiators, and combinations thereof.

7. The method of any one of claims 1 to 6, wherein the surfactant is added at a concentration of 40 to 3900 ppm based on the weight of the aqueous dispersion.

8. 8. The method of claim 1, wherein the aqueous dispersion has a solids content in the range of 10 to 65% after the polymerization reaction, and the aqueous dispersion comprises a stabilizing agent.

9. The method of claim 8 , wherein the stabilizing agent is paraffin wax.

10. The surfactant is represented by formula (2): 【Chemistry 1】 10. The method of any one of claims 1 to 9, wherein R is an alkyl group, M is a monovalent cation selected from the group consisting of hydrogen ion, alkali metal ion and ammonium ion, and l is the number of alkyl groups, varying from 1 to 2 integers.

11. The surfactant is represented by formula (4): 【Chemistry 2】 where R is an alkyl group containing 2 to 20 carbon atoms; The method according to any one of claims 1 to 9.

12. The surfactant is represented by formula (5): 【Chemistry 3】 where R is an alkyl group containing 2 to 20 carbon atoms; The method according to any one of claims 1 to 9.

13. The surfactant is represented by formula (6): 【Chemistry 4】 where R is an alkyl group containing 2 to 20 carbon atoms; The method according to any one of claims 1 to 9.

14. The surfactant is represented by formula (7): 【Chemistry 5】 where R is an alkyl group containing 2 to 20 carbon atoms; The method according to any one of claims 1 to 9.

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