Process for preparing fluoropolymer emulsion, oleophobic fluoropolymers and fibrous materials prepared therefrom

Abstract

This disclosure provides a process for preparing an oleophobic fluoropolymer emulsion. The resulting fluoropolymer emulsion exhibits excellent hydrophobic and oleophobic modification capabilities (as a coating) on ​​polyester fibers (such as polyester (PET), polypropylene (PP), and woven and nonwoven fabrics). Therefore, woven and nonwoven materials coated in this manner can be used in ventilator applications. The process for preparing the oleophobic fluoropolymer emulsion includes aqueous free radical polymerization of a monovinyl unsaturated monomer, which is carried out by combining components comprising: greater than 60 to about 100% by weight of a fluorinated monovinyl unsaturated monomer; less than 40 to about 0% by weight of a non-fluorinated monovinyl unsaturated monomer; and a surfactant.

Description

Technical Field

[0001] This disclosure relates to a method for preparing oleophobic emulsion polymers, which can be used to impart an oleophobic coating to fibrous materials (such as woven and nonwoven materials), which may subsequently form part of a filter. Prior Technology

[0002] Certain fluoropolymers are widely used as hydrophobic and oleophobic modifiers in the paper and fiber industries due to their relatively low surface free energy. There are two types of fluoropolymer products on the market: solution polymers, prepared by free radical polymerization in organic solvents, and emulsion polymers. For solution polymers, large amounts of solvent are generally required during polymerization and subsequent use, leading to safety and environmental concerns. For fluoroemulsion polymers, non-fluorinated surfactants are often used in the polymerization reaction. However, due to the low surface free energy and strong hydrophobicity of fluorinated monomers, it is inherently difficult to emulsify fluorinated monomers with common non-fluorinated surfactants. Therefore, even with high concentrations of surfactant, fluorinated monomers cannot be completely emulsified and polymerized, resulting in unstable polymer products with low fluorine content and poor hydrophobic and oleophobic modification capabilities. Although fluorinated surfactants are generally more effective than their non-fluorinated counterparts in reducing the surface tension of water, they are environmentally persistent and undesirable due to their potential for bioaccumulation in humans and wildlife.

[0003] Therefore, there is a need for improved methods for preparing emulsion-type fluoropolymers and improved fluoropolymers themselves for use in, for example, the paper and textile industries and filtration. Summary of the Invention

[0004] In summary, this disclosure provides a process for preparing fluoropolymer emulsions. The resulting fluoropolymer emulsions exhibit excellent hydrophobic and oleophobic modification capabilities (as a coating) on ​​polyester fibers (such as polyester (e.g., PET) and polypropylene (PP) woven and nonwoven fabrics). In the method of this disclosure, by controlling the intensity and time (duration) of the ultrasonic pre-emulsification step, both fluorinated and non-fluorinated monomers can be completely emulsified even with low amounts of non-fluorinated surfactants. The relative amounts of non-fluorinated and fluorinated monomers can be manipulated to achieve optimal in-process solubility of the fluorinated monomers in aqueous solutions and to adjust the desired overall fluorine content in the resulting emulsion polymer. The resulting fluoropolymer emulsion exhibits high fluorine content and excellent stability. This fluoropolymer emulsion can be used to coat polymer fibers and woven and nonwoven materials made therefrom, such as polypropylene, polyethylene, polyesters (such as polyethylene terephthalate), halogenated polyolefins (such as polytetrafluoroethylene), and other nonwoven fabrics. These coated materials exhibit excellent oleophobic and hydrophobic properties after being modified by dip-coating or spraying with the fluoropolymer emulsion. Therefore, woven and nonwoven materials coated in this way can be used in filter ventilation applications. Experimental results show that treated PET nonwoven materials can achieve an oleophobic rating of 6 or higher (according to AATCC-118-1997 oleophobicity test method) and low airflow loss. Implementation

[0005] As used in this specification and the accompanying claims, unless otherwise expressly indicated herein, the singular forms “a,” “an,” “an,” and “the” include a plurality of indicators. As used in this specification and the accompanying claims, unless otherwise expressly indicated herein, the term “or” is generally used in the sense that it includes “and / or.”

[0006] The term "approximately" generally refers to a range of values ​​that are considered equivalent to the listed values ​​(e.g., having the same function or result). In many cases, the term "approximately" may include values ​​rounded to the nearest significant figure.

[0007] The range of values ​​represented by endpoints includes all values ​​contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0008] In the first embodiment, this disclosure provides a process for preparing a fluoropolymer emulsion, comprising aqueous free radical polymerization of a monoethylene-based unsaturated monomer, by combining the following components: a. 60% to approximately 100% by weight of fluorinated monoethylene unsaturated monomers; b. Less than 40% by weight of fluorine-free monoethylene unsaturated monomers; and c. Surfactants, wherein the sum of a. and b. is 100% by weight. This provides a mixture in which the mixture is subjected to ultrasonic vibration with sufficient intensity and duration to form a preemulsion, and then subjected to free radical polymerization conditions and allowed the polymerization to continue to the desired endpoint.

[0009] In this process, an emulsifier (surfactant) is combined with water, a fluorinated monovinyl unsaturated monomer, and a monovinyl unsaturated monomer and emulsified using high-frequency vibrations applied to the reaction mixture. In one embodiment, the high-frequency vibration is ultrasonic vibration. In another embodiment, the vibration is between about 20,000 Hz and about 100,000 Hz. As used herein, free radical polymerization conditions refer to those conditions known to those skilled in the art. The reaction is generally carried out at or above room temperature, for example, between about 1 hour and about 24 hours, at about 40°C and about 100°C. Additionally, such free radical polymerization conditions also include those conditions in which the desired amount of free radical flux is generated in the reaction mixture to achieve the polymerization of fluorinated and non-fluorinated monomers. Such free radicals can be generated in solution by applying suitable thermal means or irradiation (such as, for example, ultraviolet radiation or electron beam radiation). Alternatively and advantageously, the free radical flux can be influenced by initiators known to those skilled in free radical polymerization techniques. In one embodiment, such initiators may be selected from hydrogen peroxide, potassium peroxydisulfate, ammonium peroxydisulfate, potassium persulfate, sodium persulfate, ammonium persulfate, dibenzoyl peroxide, lauryl peroxide, di-tert-butyl peroxide, 2,2'-azobisisobutyronitrile (or 2,2'-azobis(2-methylpropionitrile) – also known as AIBN), tert-butyl hydroperoxide, azobisisobutylamidine hydrochloride, and benzoyl peroxide. In one embodiment, the initiator is used in an amount of about 0.05% by weight to about 5% by weight based on the total weight of the monomers.

[0010] Therefore, in another embodiment, this disclosure provides a process for manufacturing a first-state sample, which includes assembling: a. 60% to approximately 100% by weight of fluorinated monoethylene unsaturated monomers; b. Less than 40% by weight of fluorine-free monoethylene unsaturated monomers; and c. Surfactants The total weight percentage of a. and b. is 100%. This provides a mixture in which the mixture is subsequently subjected to ultrasonic vibration with sufficient intensity and duration to form a preemulsion, followed by the addition of a free radical initiator, and the polymerization is allowed to continue to the desired endpoint.

[0011] In one embodiment, the mixture is stirred when the initiator is added and / or during the aforementioned reaction period (i.e., allowing polymerization to continue to the desired endpoint). In one embodiment, stirring is performed mechanically in the range of about 100 to about 600 revolutions per minute (rpm).

[0012] The fluorine-free monovinyl unsaturated monomers mentioned above are acrylic and vinyl species commonly used in emulsion polymerization, such as (meth)acrylates, vinyl esters, and other vinyl functional monomers. As defined, these monovinyl unsaturated monomers do not contain fluorine atoms. In one embodiment, the fluorine-free monovinyl unsaturated monomer system is selected from compounds of the following formula. (A), and (B), Each R group is independently selected from hydrogen or an alkyl group with up to 18 carbon atoms.

[0013] Compound (A) will be considered to represent acrylates and (alkyl)acrylates, and compound (B) will be considered to represent certain vinyl compounds, i.e. vinyl esters.

[0014] In another embodiment, the fluorine-free monoethylene unsaturated monomer is selected from compounds having an olefin double bond (in some cases directly attached to an aromatic ring). Examples of such compounds are styrene and α-methylstyrene. Alternatively, the olefin double bond may be substituted with an alkoxycarbonyl group, as in the case of di-n-butyl maleate. In other embodiments, the fluorine-free monoethylene unsaturated monomer may be a vinyl and acrylate compound having one or more nitrogen atoms, such as hydroxyethylacrylamide.

[0015] In another embodiment, the fluorine-free monoethylene unsaturated monomer system is selected from vinyl acetate, vinyl butyrate, vinyl octanoate and (meth)acrylate C1-C18 alkyl esters.

[0016] In another embodiment, the fluorine-free monoethylene unsaturated monomer system is selected from C1-C6 alkyl acrylates.

[0017] In one embodiment, the fluorine-free monoethylene unsaturated monomer system is selected from methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, styrene, α-methylstyrene, glycidyl methacrylate, alkyl crotonate, vinyl acetate, vinyl octanoate, di-n-butyl maleate, dioctyl maleate, hydroxyethyl acrylamide, hydroxypropyl methacrylamide, and the like.

[0018] In another embodiment, the fluorine-free monovinyl unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate, and C1-C18 alkyl (meth)acrylates. In another embodiment, the monovinyl unsaturated monomer is selected from C1-C6 alkyl acrylates. In yet another embodiment, the monovinyl unsaturated monomer is selected from ethyl acrylate and butyl acrylate.

[0019] In other embodiments, the fluorine-free monoethylene unsaturated monomer also does not contain other halogen atoms, such as chlorine, bromine or iodine.

[0020] In one embodiment, the fluorinated monoethylene unsaturated monomer has the following formula: , Wherein R is selected from hydrogen or alkyl groups with up to 18 carbon atoms, and R1 is a group of the following formula: , Wherein L is a divalent organic linker group having 1 to 20 carbon atoms, and wherein the monomer contains at least 8 and at most about 32 fluorine atoms.

[0021] As used herein, the term "divalent organic linker" describes a divalent group having carbon, hydrogen, and fluorine atoms and, as needed, one or more heteroatoms selected from oxygen, sulfur, and nitrogen.

[0022] In one embodiment, the fluorinated monoester is selected from (C1-C6) alkyl acrylate perfluorinated (C1-C14 alkyl ester) and (C1-C6 alkyl) acrylate perfluorinated (aryl ester).

[0023] In another embodiment, the fluorinated monoethylene unsaturated monomer is a perfluorinated olefin having one olefin (i.e., a double bond).

[0024] In another embodiment, the fluorinated monomer has the following formula: , Wherein R is selected from hydrogen or alkyl groups having up to 18 carbon atoms, and R1 is selected from groups of the following formula: Where m is 3, 5, 7, 9, 11, 13 or 15.

[0025] In another embodiment, the fluorinated monoethylene system is selected from one or more of the following: perfluorooctylethylene, perfluorononylethylene, perfluorotetradecylethylene, perfluorohexadecylethylene, perfluoroalkylethylene, perfluorooctyl acrylate, perfluorononyl acrylate, perfluorododecyl acrylate, perfluorotetradecyl acrylate, perfluorohexadecyl acrylate, perfluorooctyl methacrylate, perfluorotetradecyl methacrylate, perfluorononyl methacrylate, perfluorododecyl methacrylate, perfluorohexadecyl methacrylate, perfluoroalkyl methacrylate, and the like. Exemplary fluorinated monoethylene unsaturated monomers are described in the table below. Chemical name Chemical Abstract Number (CAS Number) 1H,1H,2H-Heptadecylfluoro-1-decene 21652-58-4 Perfluorodecylethylene 30389-25-4 (perfluorododecyl)ethylene 67103-05-3 1H,1H,2H,2H-heptadecyl methacrylate 1996-88-9 1H,1H,2H,2H-heptadecyl acrylate 27905-45-9 1,1,2,2-Tetrahydroperfluorotetradecane acrylate 34395-24-9 1,1,2,2-Tetrahydroperfluorododecyl methacrylate 2144-54-9 2-(perfluoroalkyl)ethyl methacrylate 65530-66-7 Perfluoroalkyl ethyl acrylate 65605-70-1 Perfluoroalkyl ethylene 97659-47-4

[0026] In yet another embodiment, the fluorinated monoethylene unsaturated monomer is ethyl acrylate (perfluorooctyl) ester.

[0027] In other embodiments, the fluorinated monovinyl unsaturated monomer does not contain other halogen atoms, such as chlorine, bromine, or iodine. Furthermore, in other embodiments, the fluorinated and non-fluorinated monovinyl unsaturated monomers disclosed herein do not contain other halogen atoms, such as chlorine, bromine, or iodine.

[0028] In this process, suitable surfactants (i.e., emulsifiers) are those classified as anionic, cationic, and nonionic surfactants. In one embodiment, the process utilizes at least one cationic surfactant and at least one nonionic surfactant. Generally, these surfactants exhibit a hydrophilic-lipophilic balance (HLB) range of about 14 to about 40. Advantageously, the process of this disclosure can utilize only fluorinated surfactants, thus providing fluorinated polymer emulsions free of fluorinated surfactants. In other embodiments, the total weight of surfactants used in the process of this disclosure may contain less than 5, less than 3, or less than 1% by weight of fluorinated surfactants.

[0029] Cationic surfactants are essentially quaternary compounds having at least one positively charged surfactant moiety, such as benzyl alkyl ammonium. In one embodiment, the cationic surfactant is selected from C8-C18 ammonium bromide and C8-C18 ammonium chloride. The "C8-C18" modifier refers to the number of carbon atoms in the surfactant and may include aliphatic and aromatic moieties. In another embodiment, the cationic surfactant is selected from C12-C18 ammonium bromide and C12-C18 ammonium chloride.

[0030] Exemplary cationic surfactants include (but are not limited to) cetyltrimethylammonium bromide (CTAB) (also known as hexadecyltrimethylammonium bromide), hexadecyltrimethylammonium chloride (CTAC), tetraethylammonium bromide, tetraethylammonium chloride, trimethyloctadecylammonium bromide, trimethyloctadecylammonium chloride, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, and the like.

[0031] Anionic surfactants are generally surfactants characterized by negatively charged hydrophilic polar groups. Exemplary anionic surfactants include sodium lauryl sulfate, sodium octylphenol glycol ether sulfate, sodium dodecylbenzenesulfonate, sodium lauryl diethylene sulfate, and tri-tert-butylphenol ammonium and penta- and octa-diol sulfonates, disodium ethoxylated nonylphenol half ester of sulfosuccinic acid, disodium n-octyldecyl sulfosuccinate, and sodium dioctyl sulfosuccinate.

[0032] Exemplary nonionic surfactants include PolyFox PF-159 (OMNOVA Solutions), polyethylene glycol ("PEG"), poly(propylene glycol) ("PPG"), ethylene oxide / propylene oxide block copolymers (such as Pluronic F-127 (BASF)), polysorbate polyoxyethylene (20) sorbitan monooleate (Tween™ 80) (Croda Americas), polyoxyethylene (20) sorbitan monostearate (Tween™ 60), polyoxyethylene (20) sorbitan monopalmitate (Tween™ 40), polyoxyethylene (20) sorbitan monolaurate (Tween™ 20)), polyoxypropylene / polyoxyethylene block copolymers (such as Pluronic L31, Plutonic 31R1, Pluronic 25R2, and Pluronic 25R4), polyoxyethylene glycol octylphenol ether, polyoxyethylene glycol alkylphenol ether, and combinations thereof.

[0033] As described above, the reaction mixture comprises greater than 60 to about 100% by weight of a fluorinated monovinyl unsaturated monomer and less than 40% by weight of a non-fluorinated monovinyl unsaturated monomer. Within this range, a specific ratio and consistency of the two monomers can be advantageously selected to maximize the solubility of the fluorinated monovinyl unsaturated monomer in an aqueous solution. In one embodiment, based on the total weight of the monomers used, the fluorinated monovinyl unsaturated monomer is present at about 80% to about 95% by weight and the monovinyl unsaturated monomer is present at about 5% to about 20% by weight.

[0034] The fluoropolymer emulsions disclosed herein exhibit excellent stability over extended periods, as illustrated in the examples below. Therefore, in another embodiment, this disclosure provides a fluoropolymer emulsion prepared by the method of this disclosure. In yet another embodiment, this disclosure provides a fluoropolymer emulsion that does not exhibit visually observable gel-like or precipitated material after storage for up to one week. In yet another embodiment, the fluoropolymer emulsion of this disclosure has an average particle size of about 100 to about 200 nm.

[0035] The resulting aqueous emulsion polymer can then be diluted with a mixture of water and an aprotic solvent (such as C1-C6 alcohol, e.g., isopropanol). In one embodiment, the diluted mixture may be about 40 to 100% by weight of water and about 0 to about 60% by weight of an aprotic solvent (such as isopropanol). The diluted emulsion polymer product can then be applied, for example, to a polymer woven or nonwoven material by simple impregnation or spraying to coat at least a portion of the surface of the fibers comprising the polymer nonwoven material. The optimal relative amounts of the diluted mixture can be empirically determined by optimizing the efficiency of coating a particular polymer nonwoven material with the emulsion polymer product. The material thus coated is allowed to dry, for example, at a temperature of about 90°C to about 180°C for a period of about 30 seconds to 10 minutes.

[0036] Exemplary polymeric woven and nonwoven materials may include polymers such as polyolefins, polyamides, polyimides, polyurethane, polyether-urethane, polyarylurethane-polyamide, polyacrylates, polyesters, nylons, cellulose, cellulose esters, polycarbonates, or combinations thereof. Exemplary polyolefins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene (PB), polyisobutylene (PIB), and copolymers of two or more of ethylene, propylene, and butene. Additionally, polymeric nonwoven materials may comprise polymers such as halogenated polymers. Exemplary halogenated polymers include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), fluorinated ethylene polymer (FEP), polyhexafluoropropylene, and polyvinylidene fluoride (PVDF). In another specific embodiment, the polymeric nonwoven material comprises ultra-high molecular weight polyethylene (UPE). UPE filter materials are typically formed from resins having a molecular weight (weight average molecular weight) greater than about 1 x 10⁶ Daltons (Da) (such as in the range of about 1 x 10⁶ to 9 x 10⁶ Da or 1.5 x 10⁶ to 9 x 10⁶ Da).

[0037] As used herein, "filter" refers to an object having a structure including a filter material (such as the polymer nonwoven material disclosed herein). The filter can take any desired form suitable for a filtration application. The material forming the filter can be the filter itself and the structural components providing the required architecture for the filter. The filter is sufficiently porous to allow gas to pass through while achieving sufficient retention time for the desired filtration operation, and can have any desired shape or configuration. Therefore, the filter of the present invention can be used as a hydrophobic filter and an oleophobic filter, particularly for filtering gases (such as air). Therefore, the filter of the present invention is particularly suitable for use as a ventilation filter. The fluoropolymer coating of these nonwoven materials makes the underlying nonwoven material more hydrophobic and oleophobic without significantly sacrificing permeability.

[0038] In one embodiment, the filter material disclosed herein (having at least a portion of a fluoropolymer coating thereon) exhibits an oil rating greater than about 6 according to AATCC Test Method 1997. In another embodiment, the filter material exhibits an oil rating of about 7 to about 8 according to AATCC Test Method 228-1997.

[0039] The air flux was measured as the rate of air passing through at a pressure of 10 kPa for a test sample with an effective membrane area of ​​0.5024 square centimeters. A rotameter was used to measure the airflow. [Example] []

[0040] [Example] [1]

[0041] 42.75 g of perfluorooctane ethyl acrylate sample, 2.25 g of butyl acrylate, 100 g of deionized water, and 1 g of sodium dodecyl sulfate were added to a beaker, and the mixture was then pre-emulsified for 60 minutes at 10% intensity using an ultrasonic processor to obtain a colorless and transparent emulsion. The emulsion was then transferred to a laboratory-scale reactor equipped with a nitrogen inlet, a thermometer, and a mechanical stirrer. After adding 0.15 g of ammonium persulfate and under a nitrogen flow, the reactor was stirred and heated to 70°C at 150 rpm, and the polymerization product was obtained after 16 hours. Subsequently, the fluoropolymer emulsion was diluted with a diluent consisting of 50% by weight water and 50% by weight isopropanol to prepare an oleophobic fluoropolymer-treated emulsion with a concentration of 3% by weight, as used below.

[0042] Prepare a piece of poly(ethylene) (PET) nonwoven fabric. After immersing the PET nonwoven fabric in a diluted fluoropolymer emulsion for 1 minute, remove it from the emulsion and drain excess water. Then place the coated fabric in an oven at 130°C for 5 minutes to obtain a fluoropolymer-treated PET nonwoven fabric. For pre- and post-treatment properties such as oil rating, air flux, and air flux loss rate (after coating the nonwoven fabric), please refer to Table 1 below. [surface] [1. PET] [Non-woven fabrics] [Comparison of data before and after oleophobic treatment.] [] sample Oil rating air flux (L / min) Air flux loss rate Before oleophobic treatment 0 3 / Example 1 8 2.7 10%

[0043] [Example] [2]

[0044] 10 g of perfluorooctane ethyl acrylate sample, 10 g of methyl methacrylate, 100 g of deionized water, and 3 g of sodium dodecyl sulfate were added to a beaker, and the mixture was pre-emulsified for 3 minutes at 70% intensity using an ultrasonic processor to obtain a pale blue emulsion. This emulsion was transferred to a reactor equipped with a nitrogen inlet, a thermometer, and a mechanical stirrer. After adding 0.2 g of ammonium persulfate and under a nitrogen flow, the reactor was stirred and heated to 70°C at 400 rpm, and the polymerization product was obtained after 8 hours. The fluoropolymer emulsion was diluted with a diluent consisting of 90% by weight water and 10% by weight isopropanol to prepare an oleophobic fluoropolymer-treated emulsion with a concentration of 3% by weight, as used below.

[0045] Following the method in Example 1, PET nonwoven fabrics are treated with an oleophobic fluoropolymer emulsion.

[0046] [Comparative Example] [1]

[0047] 10 g of perfluorooctane ethyl acrylate sample, 10 g of methyl methacrylate, 100 g of deionized water, and 3 g of sodium dodecyl sulfate were added to a beaker, and the mixture was pre-emulsified by mechanical stirring to obtain an emulsion, which was milky white. The emulsion was then transferred to a reactor equipped with a nitrogen inlet, a thermometer, and a mechanical stirrer. After adding 0.2 g of ammonium persulfate and under a nitrogen flow, the reactor was stirred and heated to 70°C at 400 rpm for 8 hours to obtain the polymerization product. The fluoropolymer emulsion was diluted with a diluent consisting of 90% by weight water and 10% by weight isopropanol to prepare an oleophobic fluoropolymer-treated emulsion with a concentration of 3% by weight.

[0048] According to the method in Example 1, the above-mentioned oleophobic fluoropolymer emulsion was used to treat PET nonwoven fabrics.

[0049] As shown in Table 2 below, the fluoropolymer emulsion disclosed herein exhibits significantly improved emulsion stability and excellent oleophobic modification of nonwoven fibers. [surface] [2.] [Example] [1] [and] [2] [And a comparison of the effects of comparative examples] [] sample weight ratio of fluorinated monomers Oleophobic grade Emulsion stability – evaluation Example 1 95% 8 No gel was observed at the end of the reaction, and no precipitation was observed after standing for one week. Example 2 50% 7 No gel was observed at the end of the reaction, and no precipitation was observed after standing for one week. Comparative Example 1 50% 0 A small amount of gel was found on the stirrer at the end of the reaction, and a precipitate was found after standing for a week.

[0050] Samples 1 to 4 in Table 3 below illustrate the effect of increasing the weight proportion of fluorinated monovinyl unsaturated monomers in emulsion polymerization, and generally show that the oleophobicity of the coated nonwoven material generally increases with the increase of the fluorine atom proportion. Furthermore, as mentioned above, the emulsion remained quite stable after one week of storage, as no gel-like or precipitated material was observed.

[0051] [Applied with coating] [Non-woven] [General procedures for the preparation of non-materials:] []

[0052] The fluoropolymer emulsion was diluted with a diluent consisting of 90% by weight water and 10% by weight isopropanol to prepare an oleophobic fluoropolymer treated emulsion with a weight concentration of 2%.

[0053] Prepare a piece of poly(ethylene) (PET) nonwoven fabric. After immersing the PET nonwoven fabric in a diluted fluoropolymer emulsion for 1 minute, remove it from the emulsion and drain excess water. Then place the coated fabric in an oven at 130°C for 5 minutes to obtain a fluoropolymer-treated PET nonwoven fabric. [surface] [3.] [Fluoropolymer emulsions with different fluorinated monomers] [PET] [Non-woven] [Oleophobic modification effect on fabrics.] sample weight ratio of fluorinated monomers Oleophobic grade Emulsion stability – evaluation Yield Granularity (according to DLS method*) 1 40% 6 No gel was observed at the end of the reaction, and no precipitation was observed after standing for one week. >95% 100 to 200 nm 2 50% 7 3 60% 7 4 >75% 8 Dynamic light scattering [] [State / Appearance] []

[0054] In the first embodiment, this disclosure provides a process for preparing a fluoropolymer emulsion, comprising aqueous free radical polymerization of a monoethylene-based unsaturated monomer, by combining the following components: a. 60% to approximately 100% by weight of fluorinated monoethylene unsaturated monomers; b. Less than 40% to approximately 0% by weight of fluorine-free monoethylene unsaturated monomers; and c. Surfactants, wherein the sum of a. and b. is 100% by weight. This provides a mixture in which the mixture is subjected to ultrasonic vibration with sufficient intensity and duration to form a preemulsion, and then subjected to free radical polymerization conditions and allowed the polymerization to continue to the desired endpoint.

[0055] In the second state sample, this disclosure provides a process similar to that of the first state sample, wherein the free radical polymerization conditions include adding a free radical initiator to the mixture.

[0056] In the third state sample, this disclosure provides a process similar to that of the second state sample, wherein the pre-emulsion is stirred during the addition of the free radical initiator.

[0057] In the fourth state sample, this disclosure provides a process as in any of the first to third state samples, wherein the fluorinated monosystem is selected from (C1-C14 alkyl) acrylates having about 8 to about 32 fluorine atoms and vinyl compounds having about 8 to about 32 fluorine atoms.

[0058] In the fifth state sample, this disclosure provides a process similar to that of the first or second state sample, wherein a. it is present in about 80% to about 95% by weight and b. it is present in about 5% to about 20% by weight.

[0059] In the sixth state sample, this disclosure provides a process similar to that of any of the first to fifth state samples, wherein the fluorinated monoethylene unsaturated monomer has the following formula: , Wherein R is selected from hydrogen or alkyl groups with up to 18 carbon atoms, and R1 is a group of the following formula: , Wherein L is a divalent organic linker group having 1 to 20 carbon atoms, and wherein the monomer contains at least 8 and at most about 32 fluorine atoms.

[0060] In the seventh state sample, this disclosure provides a process similar to that of any of the first to sixth state samples, wherein the fluorinated monoethylene unsaturated monomer has the following formula: , Wherein R is selected from hydrogen or alkyl groups having up to 18 carbon atoms, and R1 is selected from groups of the following formula: Where m is 3, 5, 7, 9, 11, 13 or 15.

[0061] In the eighth state sample, this disclosure provides a process for any of the first to seventh state samples, wherein the fluorinated monoethylene unsaturated monoester is selected from (C1-C6) alkyl acrylate perfluoro (C1-C14 alkyl ester) and (C1-C6 alkyl) acrylate perfluoro (aryl) ester.

[0062] In the ninth state sample, this disclosure provides a process for any of the states from the first to the eighth state samples, wherein the fluorinated monoethylene unsaturated monopolymer is selected from one or more of the following: perfluorooctylethylene, perfluorononylethylene, perfluorotetradecylethylene, perfluorohexadecylethylene, perfluoroalkylethylene, perfluorooctyl acrylate, perfluorononyl acrylate, perfluorododecyl acrylate, perfluorotetradecyl acrylate, perfluorohexadecyl acrylate, perfluorooctyl methacrylate, perfluorotetradecyl methacrylate, perfluorononyl methacrylate, perfluorododecyl methacrylate, perfluorohexadecyl methacrylate, and perfluoroalkyl methacrylate.

[0063] In the tenth state sample, this disclosure provides a process as in any of the first to ninth state samples, wherein the fluorinated monoethylene unsaturated monomer is ethyl acrylate (perfluorooctyl) ester.

[0064] In the eleventh state sample, this disclosure provides a process for manufacturing any of the first to tenth state samples, wherein the fluorine-free monoethylene unsaturated monomeric system is selected from compounds of the following formula. , and , Each R group is independently selected from hydrogen or an alkyl group with up to 18 carbon atoms.

[0065] In the twelfth state sample, this disclosure provides a process as in any of the first to eleventh state samples, wherein the fluorine-free monoethylene unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate and (meth)acrylate C1-C18 alkyl esters.

[0066] In the thirteenth state sample, this disclosure provides a process as in any of the first to twelfth states samples, wherein the fluorine-free monoethylene unsaturated monomer is selected from C1-C6 alkyl acrylates.

[0067] In the fourteenth state, this disclosure provides a process as in any of the first to thirteenth states, wherein the ultrasonic vibration is at a frequency of about 20,000 Hz to about 100,000 Hz.

[0068] In the fifteenth state, this disclosure provides a process as in any of the first to fourteenth states, wherein the surfactant has a hydrophilic-lipophilic balance (HLB) of about 14 to about 40.

[0069] In the sixteenth state, this disclosure provides a process as in any of the first to fifteenth states, wherein the surfactant does not contain fluorine atoms.

[0070] In the seventeenth state, this disclosure provides a process as in any of the first to sixteenth states, wherein the surfactant is present in an amount of about 1 to about 5% by weight based on the total weight of a. and b.

[0071] In the eighteenth state, this disclosure provides a process as in any of the first to seventeenth states, wherein the surfactant is selected from nonionic, anionic, and cationic surfactants.

[0072] In the nineteenth state, this disclosure provides a process as in any of the first to eighteenth states, wherein the surfactant is a mixture of at least one nonionic surfactant and at least one cationic surfactant.

[0073] In the twentieth state, this disclosure provides a process for any of the states from the first to the nineteenth states, wherein the surfactant is selected from sodium lauryl sulfate, sodium octylphenol glycol ether sulfate, sodium dodecylbenzenesulfonate, sodium lauryl diethylene glycol sulfate, and tri-tert-butylphenol ammonium and penta- and octa-diol sulfonates, disodium ethoxylated nonylphenol half ester of sulfosuccinic acid, disodium n-octyldecyl sulfosuccinate, sodium dioctyl sulfosuccinate, and C8-C18 quaternary ammonium bromide and C8-C18 quaternary ammonium chloride.

[0074] In the twenty-first state sample, this disclosure provides a process as in any of the first to twentieth state samples, wherein the surfactant is selected from trimethyloctadecylammonium bromide and trimethyloctadecylammonium chloride.

[0075] In the twenty-second state sample, this disclosure provides a process as in any of the first to twentieth state samples, wherein the surfactant is a non-fluorinated reactant.

[0076] In the twenty-third state, this disclosure provides a fluoropolymer emulsion that does not exhibit visually observable gel-like material or precipitated material after storage for up to one week, wherein the emulsion contains less than 5% by weight of fluorinated surfactant based on the total weight of surfactants.

[0077] In the twenty-fourth state sample, this disclosure provides an emulsion similar to the twenty-third state sample, wherein the emulsion contains particles having an average particle size of about 100 to about 200 nm.

[0078] In the twenty-fifth embodiment, this disclosure provides a filter material comprising a woven or nonwoven substrate having at least a portion of a fluoropolymer coating thereon, wherein the filter material exhibits an oil rating greater than about 6 according to AATCC test method 228-1997.

[0079] In the twenty-sixth sample, this disclosure provides a filter material as in the twenty-fifth sample, wherein the filter material exhibits an airflow loss rate of no more than about 15% compared to an uncoated filter material.

[0080] In the twenty-seventh state sample, this disclosure provides a filter material having a coating of at least a portion of a fluoropolymer emulsion prepared according to the first state sample, wherein the filter exhibits an oil rating greater than about 6 according to AATCC test method 228-1997.

[0081] In the twenty-eighth sample, this disclosure provides a filter material as in the twenty-fifth or twenty-seventh sample, wherein the filter material exhibits an oil rating of about 7 to about 8 according to AATCC test method 228-1997.

[0082] In the twenty-ninth state, this disclosure provides a filter material as in the twenty-fifth or twenty-seventh state, wherein the filter material comprises a polymer selected from polyolefins, fluorinated polyolefins, polyamides, polyimides, polyurethanes, polyether-urethanes, polyarylurethane-polyamides, polyacrylates, polyesters, nylons, cellulose, cellulose esters, polycarbonates, and combinations thereof.

[0083] In the thirtieth state, this disclosure provides a filter comprising filter material as described in the twenty-fifth, twenty-sixth, twenty-seventh, twenty-eighth, or twenty-ninth states.

[0084] In the thirty-first sample, this disclosure provides a method for purifying a gas, which includes passing the gas to be purified through a filter as in the thirtieth sample.

[0085] In the thirty-second state sample, this disclosure provides a filter material as in any of the twenty-fifth to twenty-ninth states, wherein the filter material contains less than 5, less than 3, or less than 1% by weight of fluorinated surfactants based on the total weight percentage of the surfactants present.

[0086] Therefore, several exemplary embodiments of this disclosure have been described, and those skilled in the art will readily understand that other embodiments can be made and used within the scope of the claims appended to this invention. Many advantages of this disclosure as covered herein have been set forth in the foregoing description. However, it should be understood that this disclosure is merely illustrative in many respects. The scope of this disclosure is, of course, defined by the language used to denote the claims appended to this invention.

Claims

1. A process for preparing a fluoropolymer emulsion comprising an aqueous free radical polymerization of a monovinyl unsaturated monomer by combining a mixture comprising: a. greater than 80 to less than 100 wt% of a fluorinated monovinyl unsaturated monomer; b. greater than 0 to less than 20 wt% of a non-fluorinated monovinyl unsaturated monomer; and c. a surfactant, wherein the sum of a. and b. is 100 wt%, thereby providing a mixture wherein the mixture is subjected to ultrasonic vibration with an intensity and duration sufficient to form a pre-emulsion, and then subjected to free radical polymerization conditions and allowed the polymerization to continue to a desired endpoint.

2. The process of claim 1, wherein the free radical polymerization conditions include adding a free radical initiator to the mixture.

3. The process of claim 1, wherein the fluorinated monoethylene unsaturated monomer has the following formula, wherein R is selected from hydrogen or an alkyl group with up to 18 carbon atoms, and R1 is a group of the following formula: , wherein L is a divalent organic linking group having 1 to 20 carbon atoms, and wherein the monomer contains at least 8 and up to about 32 fluorine atoms.

4. The process of claim 1, wherein the fluorinated monomer has the following formula, wherein R is selected from hydrogen or an alkyl group with up to 18 carbon atoms, and R1 is selected from a group of the following formula: wherein m is 3, 5, 7, 9, 11, 13 or 15.

5. The process of claim 1, wherein the fluorine-free monoethylene unsaturated monosystem is selected from compounds of the following formula, and, wherein each R is independently selected from hydrogen or an alkyl group of up to 18 carbon atoms.

6. The process of claim 1, wherein the fluorine-free monoethylene unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate and (meth)acrylate C1-C18 alkyl esters.

7. The process of claim 1, wherein the surfactant is selected from sodium lauryl sulfate, sodium octylphenol glycol ether sulfate, sodium dodecylbenzene sulfonate, sodium lauryl diethylene glycol sulfate, and tri-tert-butylphenol ammonium and penta- and octa-diol sulfonates, disodium ethoxylated nonylphenol half ester of sulfosuccinic acid, disodium n-octyldecyl sulfosuccinate, sodium dioctyl sulfosuccinate, and C8-C18 quaternary ammonium bromide and C8-C18 quaternary ammonium chloride.

8. A filter material having at least a portion of a coating of a fluoropolymer emulsion prepared according to any one of claims 1 to 7, wherein the filter exhibits an oil rating greater than about 6 according to AATCC test method 228-1997.

9. The filter material of claim 8, wherein the filter material comprises polymers selected from polyolefins, fluorinated polyolefins, polyamides, polyimides, polyurethanes, polyether-urethanes, polyarylurethane-polyamides, polyacrylates, polyesters, cellulose, cellulose esters, polycarbonates, and combinations thereof.

10. The filter material as claimed in claim 8, wherein the material exhibits an airflow loss rate of no more than about 15% when compared with an uncoated filter material.

11. A filter comprising a filter material as claimed in any one of claims 8 to 10.

12. A fluoropolymer emulsion prepared by any one of claims 1 to 7, wherein the emulsion does not exhibit visually observable gel-like material or precipitate material after storage for up to one week, wherein the emulsion contains less than 5% by weight of fluorinated surfactant based on the total weight of surfactant.