Oleophobic fluoropolymer and fibrous material made therefrom

Abstract

This invention relates to a method for preparing an oleophobic fluoropolymer emulsion. The resulting fluoropolymer emulsion exhibits excellent hydrophobic and oleophobic modification capabilities (as a coating) on ​​polyester fibers (e.g., polyester (PET), polypropylene (PP), and woven and nonwoven fabrics). Therefore, woven and nonwoven materials coated in this way can be used in ventilator filter applications.

Description

Technical Field

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

[0002] Certain fluoropolymers are widely used as hydrophobic and oleophobic modifiers in the paper and fiber industry 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 properties. 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 general, 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 (e.g., 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, 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 emulsions exhibit 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 (e.g., polyethylene terephthalate), halogenated polyolefins (e.g., polytetrafluoroethylene), and other nonwoven fabrics. These coated materials exhibit excellent oleophobic and hydrophobic properties after modification 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 greater (according to AATCC-118-1997 oleophobicity test method) and low airflow loss. Detailed Implementation

[0005] As used in this specification and the appended claims, unless otherwise expressly indicated herein, the singular forms “a,” “an,” and “the” include a plurality of indicators. As used in this specification and the appended 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 numerical 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 numerical values ​​rounded to the nearest significant figure.

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

[0008] In a first aspect, this disclosure provides a process for preparing a fluoropolymer emulsion, comprising aqueous free radical polymerization of a monovinyl unsaturated monomer, by combining components including:

[0009] a. More than 60 to about 100% by weight of fluorinated monovinyl unsaturated monomers;

[0010] b. Less than 40% by weight of fluorine-free monoethylene unsaturated monomers; and

[0011] c. Surfactant, wherein the sum of a. and b. is 100% by weight.

[0012] This provides a mixture in which the mixture is subjected to ultrasonic vibration with an intensity and duration sufficient to form a preemulsion, and then subjected to free radical polymerization conditions and allowed the polymerization to continue to the desired endpoint.

[0013] 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 one embodiment, the vibration is from about 20,000 Hz to 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, from about 1 hour to about 24 hours, at about 40°C to 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 appropriate heat or irradiation (e.g., 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, benzoyl peroxide, lauryl peroxide, di-tert-butyl peroxide, 2,2'-azobisisobutyronitrile (or 2,2'-azobis(2-methylpropionitrile) – CAS No. 78-67-1, also known as AIBN), tert-butyl hydroperoxide, azobisisobutyramidine hydrochloride, and benzoyl peroxide. In one embodiment, the initiator is used in an amount from about 0.05% by weight to about 5% by weight based on the total weight of the monomers.

[0014] Therefore, in another embodiment, this disclosure provides a process of a first aspect, which includes a combination of:

[0015] a. More than 60 to about 100% by weight of fluorinated monovinyl unsaturated monomers;

[0016] b. Less than 40% by weight of fluorine-free monoethylene unsaturated monomers; and

[0017] c. Surfactants

[0018] The total weight percentage of a. and b. is 100%.

[0019] This provides a mixture in which the mixture is subsequently subjected to ultrasonic vibration with an intensity and duration sufficient to form a preemulsion, followed by the addition of a free radical initiator, and the polymerization is allowed to continue to the desired endpoint.

[0020] 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).

[0021] The fluorine-free monovinyl unsaturated monomers mentioned above are those acrylic and vinyl substances commonly used in emulsion polymerization technology, 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 is selected from compounds of the following formula:

[0022]

[0023] and

[0024]

[0025] Each R is independently selected from hydrogen or an alkyl group with up to 18 carbon atoms.

[0026] Compound (A) is considered to represent acrylates and (alkyl)acrylates, and compound (B) is considered to represent certain vinyl compounds, that is, vinyl esters.

[0027] 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 vinyl and acrylate compounds having one or more nitrogen atoms, such as hydroxyethylacrylamide.

[0028] In another embodiment, the fluorine-free monoethylene unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate, and (meth)acrylic acid C1-C. 18 Alkyl esters.

[0029] In another embodiment, the fluorine-free monoethylene unsaturated monomer is selected from C1-C6 alkyl acrylates.

[0030] In one embodiment, the fluorine-free monovinyl unsaturated monomer 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, hydroxyethylacrylamide, hydroxypropyl methacrylamide, etc.

[0031] In another embodiment, the fluorine-free monoethylene unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate, and (meth)acrylic acid C1-C. 18 Alkyl esters. In another embodiment, the monovinyl unsaturated monomer is selected from C1-C6 alkyl esters of acrylate. In another embodiment, the monovinyl unsaturated monomer is selected from ethyl acrylate and butyl acrylate.

[0032] In other embodiments, the fluorine-free monoethylene unsaturated monomer also does not contain other halogen atoms, such as chlorine, bromine or iodine.

[0033] In one embodiment, the fluorinated monoethylene unsaturated monomer has the following formula:

[0034]

[0035] Where R is selected from hydrogen or an alkyl group having up to 18 carbon atoms, and R 1 Groups that are the following:

[0036]

[0037] Wherein L is a divalent organic linker having 1 to 20 carbon atoms, and wherein the monomer contains at least 8 and up to about 32 fluorine atoms.

[0038] As used herein, the term "divalent organic linker" describes a divalent group having carbon, hydrogen, and fluorine atoms and optionally one or more heteroatoms selected from oxygen, sulfur, and nitrogen.

[0039] In one embodiment, the fluorinated monomer is selected from (C1-C6) alkyl acrylate perfluorinated (C1-C6) 14 Alkyl esters and (C1-C6 alkyl) acrylates perfluorinated (aryl esters).

[0040] In another embodiment, the fluorinated monoethylene unsaturated monomer is a perfluorinated olefin having one olefin (i.e., a double bond).

[0041] In another embodiment, the fluorinated monomer has the following formula:

[0042]

[0043] Where R is selected from hydrogen or an alkyl group having up to 18 carbon atoms, and R 1 Groups selected from the following formulas:

[0044]

[0045] and

[0046]

[0047] Where m is 3, 5, 7, 9, 11, 13 or 15.

[0048] In another embodiment, the fluorinated monomer 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, etc. Exemplary fluorinated monoethylene unsaturated monomers are described in the table below.

[0049] 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

[0050] In yet another embodiment, the fluorinated monoethylene unsaturated monomer is ethyl acrylate (perfluorooctyl) ester.

[0051] 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 monovinyl unsaturated monomer and the non-fluorinated monovinyl unsaturated monomer of this disclosure do not contain other halogen atoms, such as chlorine, bromine, or iodine.

[0052] In this process, suitable surfactants (i.e., emulsifiers) are those classified as anionic, cationic, and nonionic surfactants. In one embodiment, the process uses 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 use 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.

[0053] Cationic surfactants are essentially quaternary compounds having at least one positively charged surface-active moiety, such as benzyl alkyl ammonium. In one embodiment, the cationic surfactant is selected from C8-C bromides. 18 Ammonium and C8-C chloride 18 Ammonium. "C8-C" 18 "Modifiers refer to the number of carbon atoms in a surfactant and may include aliphatic and aromatic moieties. In another embodiment, the cationic surfactant is selected from C bromide." 12 -C 18 Ammonium and C chloride 12 -C 18 Ammonium.

[0054] 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, etc.

[0055] 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 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, and sodium dioctyl sulfosuccinate.

[0056] Exemplary nonionic surfactants include PolyFox PF-159 (OMNOVA Solutions), polyethylene glycol (“PEG”), poly(propylene glycol) (“PPG”), ethylene oxide / propylene oxide block copolymers (e.g., Pluronic F-127 (BASF)), polysorbate polyoxyethylene (20) sorbitan monooleate (Tween) TM 80)(Croda Americas) and polyoxyethylene (20) sorbitan monostearate (Tween TM 60), Polyoxyethylene (20) sorbitan monopalmitate (Tween TM 40), Polyoxyethylene (20) sorbitan monolaurate (Tween) TM 20), polyoxypropylene / polyoxyethylene block copolymers (e.g., Pluronic L31, Plutonic 31R1, Pluronic 25R2 and Pluronic 25R4), polyoxyethylene glycol octylphenol ether, polyoxyethylene glycol alkylphenol ether and combinations thereof.

[0057] As described above, the reaction mixture comprises more 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, a. (the fluorinated monovinyl unsaturated monomer) is present at about 80% to about 95% by weight and b. (the monovinyl unsaturated monomer) is present at about 5% to about 20% by weight.

[0058] The fluoropolymer emulsions of this disclosure exhibit excellent stability over extended periods, as illustrated in the examples below. Therefore, in another aspect, this disclosure provides fluoropolymer emulsions prepared by the methods of this disclosure. In yet another aspect, 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 another embodiment, the fluoropolymer emulsions of this disclosure have an average particle size of about 100 to about 200 nm.

[0059] The resulting aqueous emulsion polymer can then be diluted with a mixture of water and an aprotic solvent (e.g., C1-C6 alcohol, such as 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 (e.g., 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 amount 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 dried, for example, at a temperature of about 90°C to about 180°C for about 30 seconds to 10 minutes.

[0060] Exemplary polymeric woven and nonwoven materials may include polymers such as polyolefins, polyamides, polyimides, polysulfones, polyether-sulfones, polyarylsulfone-polyamides, polyacrylates, polyesters, nylon, 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 polymers (FEP), polyhexafluoropropylene, and polyvinylidene fluoride (PVDF). In another specific embodiment, the polymeric nonwoven material comprises ultra-high molecular weight polyethylene (UPE). UPE filter materials typically have a molecular weight greater than about 1 x 10⁻⁶. 6 Dalton (e.g., in about 1x10) 6 Up to 9x10 6 Da or 1.5x10 6 Up to 9x10 6 Resins are formed with a molecular weight (weight average molecular weight) within the range of Da.

[0061] As used herein, "filter" refers to an object having a structure including a filter material (such as the polymeric nonwoven material disclosed herein). The filter can take any desired form suitable for the 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 filters of the present invention can be used as hydrophobic and oleophobic filters, particularly in filtering gases (e.g., air). Thus, the filters of the present invention are particularly suitable for use as ventilation filters. The fluoropolymer coating of these nonwoven materials makes the underlying nonwoven material more hydrophobic and oleophobic without significantly sacrificing permeability.

[0062] In one embodiment, the filter material of this disclosure (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.

[0063] 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 resulting airflow.

[0064] Example

[0065] Example 1

[0066] 42.75 g of perfluorooctane ethyl acrylate (CAS No. 27905-45-9), 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, thermometer, and 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 wt% water and 50 wt% isopropanol to prepare an oleophobic fluoropolymer-treated emulsion with a concentration of 3% by weight, as used below.

[0067] 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.

[0068] Table 1. Comparison of data before and after oleophobic treatment of PET nonwoven fabrics.

[0069]

[0070] Example 2

[0071] 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. The 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 wt% water and 10 wt% isopropanol to prepare an oleophobic fluoropolymer-treated emulsion with a weight concentration of 3% used below.

[0072] Following the method in Example 1, PET nonwoven fabrics were treated with an oleophobic fluoropolymer emulsion.

[0073] Comparative Example 1

[0074] 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 pipe, 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 wt% water and 10 wt% isopropanol to prepare an oleophobic fluoropolymer-treated emulsion with a weight concentration of 3%.

[0075] According to the method in Example 1, the above-mentioned oleophobic fluoropolymer emulsion was used to treat PET nonwoven fabrics.

[0076] As shown in Table 2 below, the fluoropolymer emulsions of this disclosure exhibit significantly improved performance in emulsion stability and excellent oleophobic modification of nonwoven fibers.

[0077] Table 2. Comparison of the effects of Examples 1 and 2 and the comparative examples

[0078]

[0079]

[0080] 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 materials 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.

[0081] General procedure for preparing coated nonwoven materials:

[0082] 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%.

[0083] 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.

[0084] Table 3. Oleophobic modification effect of fluoropolymer emulsions with different fluorinated monomers on PET nonwoven fabrics.

[0085]

[0086] Dynamic light scattering

[0087] aspect

[0088] In a first aspect, this disclosure provides a process for preparing a fluoropolymer emulsion, comprising aqueous free radical polymerization of a monovinyl unsaturated monomer, by combining components including:

[0089] a. More than 60 to about 100% by weight of fluorinated monovinyl unsaturated monomers;

[0090] b. Less than 40 to about 0% by weight of fluorine-free monoethylene unsaturated monomers; and

[0091] c. Surfactant, wherein the sum of a. and b. is 100% by weight.

[0092] This provides a mixture in which the mixture is subjected to ultrasonic vibration with an intensity and duration sufficient to form a preemulsion, and then subjected to free radical polymerization conditions and allowed the polymerization to continue to the desired endpoint.

[0093] In a second aspect, this disclosure provides a process according to the first aspect, wherein the free radical polymerization conditions include adding a free radical initiator to the mixture.

[0094] In a third aspect, this disclosure provides a process according to the second aspect, wherein the preemulsion is stirred during the addition of the free radical initiator.

[0095] In a fourth aspect, this disclosure provides a process according to any one of the first to third aspects, wherein the fluorinated monomer is selected from (C1-C2) monomers having about 8 to about 32 fluorine atoms. 14 Alkyl acrylates and vinyl compounds having about 8 to about 32 fluorine atoms.

[0096] In a fifth aspect, this disclosure provides a process according to the first or second aspect, 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.

[0097] In a sixth aspect, this disclosure provides a process according to any one of the first to fifth aspects, wherein the fluorinated monoethylene unsaturated monomer has the following formula:

[0098]

[0099] Where R is selected from hydrogen or an alkyl group having up to 18 carbon atoms, and R 1 Groups that are the following:

[0100]

[0101] Wherein L is a divalent organic linker having 1 to 20 carbon atoms, and wherein the monomer contains at least 8 and up to about 32 fluorine atoms.

[0102] In a seventh aspect, this disclosure provides a process according to any one of the first to sixth aspects, wherein the fluorinated monoethylene unsaturated monomer has the following formula:

[0103]

[0104] Where R is selected from hydrogen or an alkyl group having up to 18 carbon atoms, and R 1 Groups selected from the following formulas:

[0105]

[0106] and

[0107]

[0108] Where m is 3, 5, 7, 9, 11, 13 or 15.

[0109] In the eighth aspect, this disclosure provides a process according to any one of the first to seventh aspects, wherein the fluorinated monovinyl unsaturated monomer is selected from (C1-C6) alkyl acrylate perfluorinated (C1-C6) 14 Alkyl esters and (C1-C6 alkyl) acrylates perfluoro(aryl) esters.

[0110] In a ninth aspect, this disclosure provides a process according to any one of the first to eighth aspects, wherein the fluorinated monoethylene unsaturated monomer 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.

[0111] In a tenth aspect, this disclosure provides a process according to any one of the first to ninth aspects, wherein the fluorinated monovinyl unsaturated monomer is ethyl acrylate (perfluorooctyl) ester.

[0112] In the eleventh aspect, this disclosure provides a process according to any one of the first to tenth aspects, wherein the fluorine-free monoethylene unsaturated monomer is selected from compounds of the following formula.

[0113]

[0114] and

[0115]

[0116] Each R is independently selected from hydrogen or an alkyl group with up to 18 carbon atoms.

[0117] In a twelfth aspect, this disclosure provides a process according to any one of the first to eleventh aspects, wherein the fluorine-free monoethylene unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate, and (meth)acrylic acid C1-C. 18 Alkyl esters.

[0118] In a thirteenth aspect, this disclosure provides a process according to any one of the first to twelfth aspects, wherein the fluorine-free monoethylene unsaturated monomer is selected from C1-C6 alkyl acrylates.

[0119] In the fourteenth aspect, this disclosure provides a process according to any one of the first to thirteenth aspects, wherein the ultrasonic vibration is at a frequency of about 20,000 Hz to about 100,000 Hz.

[0120] In the fifteenth aspect, this disclosure provides a process according to any one of the first to fourteenth aspects, wherein the surfactant has a hydrophilic-lipophilic balance (HLB) of about 14 to about 40.

[0121] In a sixteenth aspect, this disclosure provides a process according to any one of the first to fifteenth aspects, wherein the surfactant is free of fluorine atoms.

[0122] In the seventeenth aspect, this disclosure provides a process according to any one of the first to sixteenth aspects, wherein the surfactant is present in about 1 to about 5% by weight based on the total weight of a. and b.

[0123] In the eighteenth aspect, this disclosure provides a process according to any one of the first to seventeenth aspects, wherein the surfactant is selected from nonionic, anionic and cationic surfactants.

[0124] In the nineteenth aspect, this disclosure provides a process according to any one of the first to eighteenth aspects, wherein the surfactant is a mixture of at least one nonionic surfactant and at least one cationic surfactant.

[0125] In a twentieth aspect, this disclosure provides a process according to any one of the first to nineteenth aspects, wherein the surfactant is selected from 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, sodium dioctyl sulfosuccinate, and C8-C bromide. 18 Quaternary ammonium and C8-C chloride 18 Grade IV ammonium.

[0126] In the twenty-first aspect, this disclosure provides a process according to any one of the first to twentieth aspects, wherein the surfactant is selected from trimethyloctadecylammonium bromide and trimethyloctadecylammonium chloride.

[0127] In the twentieth aspect, this disclosure provides a process according to any one of the first to twentieth aspects, wherein the surfactant is a non-fluorinated reactant.

[0128] In a twenty-third aspect, this disclosure provides a fluoropolymer emulsion that does not exhibit visually observable gel-like or precipitated material after storage for up to one week, and wherein said emulsion contains less than 5% by weight of fluorinated surfactant based on the total weight of surfactants.

[0129] In the twenty-fourth aspect, this disclosure provides an emulsion according to the twenty-third aspect, wherein the emulsion comprises particles having an average particle size of about 100 to about 200 nm.

[0130] In a twentieth aspect, 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.

[0131] In the twenty-sixth aspect, this disclosure provides a filter material according to the twenty-fifth aspect, wherein the filter material exhibits an airflow loss rate of no more than about 15% compared to an uncoated filter material.

[0132] In a twentieth aspect, this disclosure provides a filter material having at least a portion of a coating of a fluoropolymer emulsion made according to the first aspect, wherein the filter exhibits an oil rating greater than about 6 according to AATCC test method 228-1997.

[0133] In the twentieth aspect, this disclosure provides a filter material according to the twentieth or twentieth aspect, wherein the filter material exhibits an oil rating of about 7 to about 8 according to AATCC test method 228-1997.

[0134] In a twentieth aspect, this disclosure provides a filter material according to a twentieth or twentieth aspect, wherein the filter material comprises a polymer selected from polyolefins, fluorinated polyolefins, polyamides, polyimides, polysulfones, polyether-sulfones, polyarylsulfone-polyamides, polyacrylates, polyesters, nylons, cellulose, cellulose esters, polycarbonates, and combinations thereof.

[0135] In a thirtieth aspect, this disclosure provides a filter comprising the filter material described in aspects twenty-five, twenty-six, twenty-seven, twenty-eight, or twenty-nine.

[0136] In a thirty-first aspect, this disclosure provides a method for purifying a gas, comprising passing the gas to be purified through a filter according to the thirty-first aspect.

[0137] In the thirty-second aspect, this disclosure provides a filter material according to any one of the twenty-fifth to twenty-ninth aspects, wherein the filter material comprises less than 5, less than 3, or less than 1% by weight of a fluorinated surfactant based on the total weight percentage of the surfactants present.

[0138] Therefore, having described several illustrative embodiments of this disclosure, those skilled in the art will readily recognize that other embodiments can be made and used within the scope of the appended claims. Many advantages of the disclosure covered herein have been set forth in the foregoing description. However, it should be understood that this disclosure is illustrative in many respects only. The scope of this disclosure is, of course, defined by the language indicated in the appended claims.

Claims

1. A method for preparing a fluoropolymer emulsion, comprising aqueous free radical polymerization of a monovinyl unsaturated monomer, wherein the composition comprises components including: a. More than 60 to 100% by weight of fluorinated monovinyl unsaturated monomers; b. Less than 40% to 0% by weight of fluorine-free monoethylene unsaturated monomers The fluorinated monoethylene unsaturated monomer and the non-fluorinated monoethylene unsaturated monomer therein do not contain other halogen atoms; and c. Surfactant, wherein the sum of a. and b. is 100% by weight. This provides a mixture, wherein the mixture is subjected to ultrasonic vibration with an intensity and duration sufficient to form a preemulsion, and then the mixture is subjected to free radical polymerization conditions and the polymerization is allowed to continue to the desired endpoint.

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

3. The method of claim 2, wherein the preemulsion is stirred during the addition of the free radical initiator.

4. The method according to claim 1, wherein the fluorinated monoethylene unsaturated monomer is selected from... C1-C with 8 to 32 fluorine atoms 14 Alkyl acrylates, and Vinyl compounds having 8 to 32 fluorine atoms.

5. The method of claim 1, wherein a. it is present in 80% to 95% by weight and b. it is present in 5% to 20% by weight.

6. The method according to claim 1, wherein the fluorinated monoethylene unsaturated monomer has the following formula: ， wherein R is selected from hydrogen or an alkyl group of up to 18 carbon atoms, and R 1 is a group of the formula: ， Wherein L is a divalent organic linker having 1 to 20 carbon atoms, and wherein the monomer contains at least 8 and at most 32 fluorine atoms.

7. The method according to claim 1, wherein the fluorinated monoethylene unsaturated monomer has the following formula: ， wherein R is selected from hydrogen or an alkyl group of up to 18 carbon atoms, and R 1 is selected from the group consisting of the following formulae: ， ， ， Where m is 3, 5, 7, 9, 11, 13 or 15.

8. The method according to claim 1, wherein the fluorinated monovinyl unsaturated monomer is selected from C1-C6 alkylacrylic acid perfluorinated C1-C6. 14 Alkyl esters and C1-C6 alkyl acrylate perfluoroaryl esters.

9. The method according to claim 1, wherein the fluorinated monoethylene unsaturated monomer 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.

10. The method according to claim 1, wherein the fluorinated monovinyl unsaturated monomer is perfluorooctyl ethyl acrylate.

11. The method according to claim 1, wherein the fluorine-free monoethylene unsaturated monomer is selected from compounds of the following formula. ， and ， Each R is independently selected from hydrogen or an alkyl group with up to 18 carbon atoms.

12. The method according to claim 1, wherein the fluorine-free monoethylene unsaturated monomer is selected from vinyl acetate, vinyl butyrate, vinyl octanoate, and (meth)acrylic acid C1-C14. 18 Alkyl esters.

13. The method according to claim 1, wherein the fluorine-free monoethylene unsaturated monomer is selected from C1-C6 alkyl acrylates.

14. The method of claim 1, wherein the ultrasonic vibration is at a frequency of 20,000 Hz to 100,000 Hz.

15. The method of claim 1, wherein the surfactant has a hydrophilic-lipophilic balance (HLB) of 14 to 40.

16. The method of claim 15, wherein the surfactant is free of fluorine atoms.

17. The method of claim 16, wherein the surfactant is present in 1 to 5% by weight based on the total weight of a. and b.

18. The method of claim 1, wherein the surfactant is selected from nonionic, anionic, and cationic surfactants.

19. The method according to claim 1, wherein the surfactant is a mixture of at least one nonionic surfactant and at least one cationic surfactant.

20. The method according to claim 1, 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-C bromide. 18 Quaternary ammonium and C8-C chloride 18 Grade IV ammonium.

21. The method according to claim 1, wherein the surfactant is selected from trimethyloctadecylammonium bromide and trimethyloctadecylammonium chloride.

22. A fluoropolymer emulsion prepared by the method according to any one of claims 1-21, and which does not exhibit a 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 a fluorinated surfactant based on the total weight of the surfactant.

23. The emulsion according to claim 22, having an average particle size of 100 to 200 nm.

24. A filter material comprising a woven or nonwoven substrate having at least a portion of a coating of a fluoropolymer emulsion prepared by any one of claims 1-21, wherein the filter material exhibits an oil rating greater than 6 according to AATCC test method 228-1997.

25. The filter material of claim 24, wherein the material exhibits an airflow loss rate of no more than 15% compared to an uncoated filter material.

26. A filter material having at least a portion of a coating of a fluoropolymer emulsion made according to claim 1, wherein the filter material exhibits an oil rating greater than 6 according to AATCC test method 228-1997.

27. The filter material according to claim 24 or 26, wherein the filter material exhibits an oil rating of 7 to 8 according to AATCC test method 228-1997.

28. The filter material according to claim 24 or 26, wherein the filter material comprises a polymer selected from polyolefins, fluorinated polyolefins, polyamides, polyimides, polysulfones, polyether-sulfones, polyarylsulfone-polyamides, polyacrylates, polyesters, cellulose, cellulose esters, polycarbonates, and combinations thereof.

29. A filter comprising the filter material according to claim 24, 25, 26, 27 or 28.

30. A method for purifying a gas, comprising passing the gas to be purified through a filter according to claim 29.

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