Chemically functionalized, spunbond nylon nonwoven materials and methods of making and using the same

Abstract

This article describes chemically functionalized spunbond nylon nonwoven materials and their preparation methods, wherein homogeneous spunbond nylon fibers are chemically functionalized using an aqueous reaction mixture containing aminoalkyl (meth)acryloyl monomers. Such chemically functionalized nonwoven materials disclosed herein can be used for fluid filtration.

Description

Technical Field

[0001] This disclosure relates to functionalized spunbond nylon nonwoven materials and methods for their preparation. This disclosure also relates to filters and methods for filtering fluids using the functionalized nonwoven materials. The functionalized nonwoven materials can be used for the selective filtration and removal of biological materials, such as biocontaminants, from biological samples. Summary of the Invention

[0002] People are looking for grafting substrates that offer high functionality while minimizing dimensional changes during use.

[0003] In one aspect, a chemically functionalized nonwoven material is disclosed. This chemically functionalized nonwoven material comprises:

[0004] A spunbond nonwoven material comprising multiple homogeneous fibers, wherein the multiple homogeneous fibers comprise nylon, and wherein at least a portion of the multiple homogeneous fibers is chemically functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

[0005] In some embodiments, the aqueous reaction mixture further comprises a hydrophilic monomer.

[0006] In some embodiments, the aqueous reaction mixture is substantially free of polyoxyalkylene monomers.

[0007] In another aspect, a nonwoven material is described, comprising a chemically functionalized nonwoven material, wherein the chemically functionalized nonwoven material comprises:

[0008] A spunbond nonwoven material comprising multiple homogeneous fibers, wherein the multiple homogeneous fibers comprise nylon, and wherein at least a portion of the multiple homogeneous fibers is chemically functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

[0009] In another aspect, a filter media comprising a chemically functionalized nonwoven material is described, comprising: a spunbond nonwoven material comprising a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprises nylon, and wherein at least a portion thereof is chemically functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

[0010] In another aspect, a method for preparing chemically functionalized nonwoven materials is described, the method comprising:

[0011] Provided a spunbond nonwoven material comprising a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprises nylon; and

[0012] Contacting a spunbond nonwoven material with an aqueous reaction mixture, the mixture comprising:

[0013] Aminoalkyl (meth)acryloyl monomers;

[0014] Optionally, hydrophilic monomers; and

[0015] Optionally, (meth)acryloyl epoxide monomer; and

[0016] Exposing spunbond nonwoven materials to radiation.

[0017] The foregoing description is not intended to depict every embodiment. Details of one or more embodiments of the invention are also set forth in the following description. Other features, objectives, and advantages will become apparent from the specification and claims. Detailed Implementation

[0018] As used in this article, terminology

[0019] “a,” “an,” and “the” are used interchangeably and refer to one or more; and

[0020] "And / or" is used to indicate that one or both of the stated situations may occur, such as A and / or B including (A and B) and (A or B);

[0021] "(Meth)acrylate" refers to compounds containing the structures of acrylate (CH2=CHCOOR) or methacrylate (CH2=CCH3COOR) or combinations thereof; and

[0022] A monomer is a molecule that can be polymerized to form part of the basic structure of a polymer.

[0023] "Alkyl" refers to a saturated monovalent hydrocarbon with one to twelve carbon atoms, either straight-chain or branched, cyclic or acyclic, such as methyl, ethyl, 1-propyl, 2-propyl, pentyl, etc.

[0024] "alkylene" refers to a straight-chain saturated divalent hydrocarbon having one to twelve carbon atoms or a branched-chain saturated divalent hydrocarbon having three to twelve carbon atoms, such as methylene, ethylene, propylene, 2-methylpropylene, pentylene, hexylene, etc.

[0025] "Aryl" refers to a monovalent aromatic group, such as phenyl or naphthyl.

[0026] Similarly, in this article, the ranges expressed by the endpoints include all numbers contained within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0027] Similarly, in this article, the phrase “at least one” includes all numbers from one to larger (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0028] As used in this article, "including at least one of A, B, and C" means element A itself, element B itself, element C itself, A and B, A and C, B and C, and all combinations of the three.

[0029] In this disclosure, it has been found that when nylon fibers are chemically functionalized using the aqueous reaction mixtures disclosed herein, spunbond nylon nonwovens exhibit more monomers derived thereon and better binding capacity compared to polypropylene nonwovens. Furthermore, the derived nylon spunbond nonwovens demonstrate better dimensional stability compared to nylon meltblown fibers. Such nylon spunbond fibers can be used in nonwoven form, and in some embodiments, they can be used as filter media.

[0030] The fibers disclosed herein are homogeneous fibers comprising nylon. As used herein, "homogeneous fiber" refers to a fiber having a homogeneous composition in both diameter and length. The fibers comprise nylon and may comprise nylon copolymers or blends of nylon with another polymer and / or additives.

[0031] Exemplary nylons include: nylon 6; nylon 6,6; nylon 1,6; nylon 11; nylon 12; nylon 4,6; nylon 4; nylon 1,4; nylon 510; nylon TMDT (or nylon 6, 3, T) or combinations thereof.

[0032] The fibers disclosed herein may have a circular cross-section; however, other cross-sections may also be used, such as triangular, square, rectangular, pentagonal, hexagonal, heptagonal, octagonal, star-shaped, elliptical, trilobal, and tetralobal.

[0033] The fibers used to implement this disclosure may have any average fiber diameter and may be continuous fibers, random fibers, and / or short fibers. For example, in some embodiments, the fibers (i.e., single fibers) may have an average fiber diameter of at least 5, 8, or even 10 micrometers and at most 12, 15, 18, 20, 22, or even 25 micrometers.

[0034] The diameter of a fiber can be measured using techniques known in the art. In some embodiments, the diameter of the fiber can be determined by microscopic examination (e.g., optical or scanning electron microscopy), wherein a cross-section of the fiber is taken and observed at magnification to determine the diameter. In some embodiments, the diameter of the fiber can be calculated by measuring the pressure drop across the ends of the fiber web. The effective fiber diameter (EFD) can be calculated as described in the Examples section below.

[0035] The spunbond fibers described herein are typically manufactured using techniques known in the art for producing filaments. In melt spinning, the polymer is heated, passed through a spinneret, and the fiber solidifies upon cooling. As used herein, the term "melt spinning" refers to fibers formed by extruding molten fibers from a set of orifices, allowing the fibers to cool and (at least partially) solidify to form fibers, passing the fibers through an air chamber (which may contain a moving airflow) to aid in cooling and solidification, and then passing the resulting fibers through a drawing (i.e., stretching) device to stretch the fibers.

[0036] In some embodiments, the spunbond fibers are in a nonwoven form. As used herein, the term "nonwoven" refers to a fabric having a monofilament structure in which the monofilaments are randomly and / or unidirectionally interwoven in a felt-like manner. Nonwoven substrates can be manufactured using any process generally known for producing nonwoven webs.

[0037] Spunbond nonwoven fiber webs can be formed using known conventional methods, wherein melt-spun fibers are deposited on a moving belt to form a nonwoven continuous fiber web with interfiber bonds.

[0038] In some embodiments, the nonwoven web can be made by air-laid spunbond fibers. Air-laid nonwoven fiber webs can be prepared using equipment such as the RANDO WEBBER, available for example from Rando Machine Company in Massand, New York. In some embodiments, an air-laid type called gravity lamination can be used, as described, for example, in U.S. Patent Publication No. 2011 / 0247839 (Lalouch et al.), the disclosure of which is incorporated herein by reference. The nonwoven fiber web can be densified and strengthened, for example, by techniques such as cross-lapping, stitching, needle punching, hydroentangling, chemical bonding, and / or thermal bonding.

[0039] Unless otherwise stated, the nonwoven fiber webs according to this disclosure may have any basis weight, thickness, porosity, and / or density. In one embodiment, the basis weight of the nonwoven material is at least 50, 60, 80, or even up to 100 g / m². 2 ); up to 150, 200, 225 or even 250 g / m2.

[0040] In this disclosure, spunbond fibers, such as those described above, are contacted with an aqueous reaction mixture and subjected to radiation to cause the monomers to react and generate fibers.

[0041] In this disclosure, spunbond fibers are exposed to an aqueous mixture of monomers, which are then reacted together to functionalize the fibers using amine groups (which may include quaternary ammonium groups).

[0042] The aqueous reaction mixture contains an aminoalkyl (meth)acryloyl monomer; optionally a hydrophilic monomer and optionally a (meth)acryloyl epoxide monomer.

[0043] The aminoalkyl (meth)acryloyl monomer is an amino (meth)acrylate or amino (meth)acrylamide of formula I or a quaternary ammonium salt thereof.

[0044] I

[0045] In equation I, R 1 R is hydrogen or methyl, preferably methyl; L is —O— or —NH—; and Y is an alkylene group (e.g., an alkylene group having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms). Each R 2 Independently hydrogen or alkyl, preferably C1-C4 alkyl. Alternatively, two Rs 2 The groups, combined with the nitrogen atoms they are attached to, can form aromatic, partially unsaturated (i.e., unsaturated but not aromatic), or saturated heterocyclic groups, wherein the heterocyclic group may optionally be fused with a second ring, which is aromatic (e.g., benzene), partially unsaturated (e.g., cyclohexene), or saturated (e.g., cyclohexane). The counterions of quaternary ammonium salts are typically halides, sulfates, phosphates, nitrates, etc. Such monomers can be quaternary ammonium monomers, i.e., those with -N(R) 2 3 + X − Groups, where each R 2 Consistent with the definition, and X − It is a counterion. Monomers with quaternary ammonium groups can react directly with fibers, or aminoalkyl (meth)acryloyl monomers with primary, secondary, or tertiary amine groups can react with fibers and then be converted to quaternary ammonium groups through alkylation.

[0046] In some embodiments of Equation I, the two R 2 All groups are hydrogen. In other embodiments, one R 2 The group is hydrogen, and the other is an alkyl group having 1 to 10, 1 to 6, or 1 to 4 carbon atoms. In yet other embodiments, R 2Groups combine with the nitrogen atoms to which they are attached to form heterocyclic groups. Heterocyclic groups include at least one nitrogen atom and may contain other heteroatoms such as oxygen or sulfur. Exemplary heterocyclic groups include, but are not limited to, imidazole groups. Heterocyclic groups may be fused with other rings such as benzene, cyclohexene, or cyclohexane. Exemplary heterocyclic groups fused with other rings may include benzimidazol groups.

[0047] In one embodiment, the aminoalkyl (meth)acryloyl monomer of formula (I) is a quaternary ammonium salt as in formula (II):

[0048] II

[0049] Wherein R1 is hydrogen or methyl, preferably methyl; L is –O- or –NH-; and Y is an alkylene (e.g., an alkylene having 2 to 10 carbon atoms, 2 to 6 carbon atoms, or 2 to 4 carbon atoms). R2, R3, and R4 are independently aryl or alkyl, preferably C1-C4 alkyl; and X - It is a counterion.

[0050] Exemplary quaternary ammonium salts of aminoalkyl (meth)acryloyl monomers include, but are not limited to, (meth)acrylamidoalkyltrimethylammonium salts (e.g., 3-methacrylamidopropyltrimethylammonium chloride and 3-acrylamidopropyltrimethylammonium chloride) and (meth)acryloyloxyalkyltrimethylammonium salts (e.g., 2-acryloyloxyethyltrimethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, 3-methacryloyloxy-2-hydroxypropyltrimethylammonium chloride, 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride, 2-acryloyloxyethyltrimethylmethylammonium sulfate).

[0051] In some embodiments, the aqueous reaction mixture comprises at least 10, 20, 25, 30, 40, or even 50% by weight of aminoalkyl (meth)acryloyl monomer to total monomers. In some embodiments, the aqueous reaction mixture comprises up to 55%, 60%, 70%, 80%, 90%, 95%, 98%, 99%, or even 100% by weight of aminoalkyl (meth)acryloyl monomer relative to total monomers.

[0052] In some embodiments, the aqueous solution further includes a hydrophilic monomer, which is an olefinic unsaturated compound having hydrophilic properties. As used herein, a “hydrophilic monomer” is a polymerizable monomer having at least 1 wt.%, preferably at least 5 wt.%, of water miscibility (water in the monomer) without reaching a cloud point, excluding poly(epoxide) monomers, and free of acidic functional groups or groups that would delay functionalization polymerization.

[0053] Examples of suitable hydrophilic monomers include 2-hydroxyethyl methacrylate (HEMA), 2-ethoxyethyl methacrylate (2-EOEMA), 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2,3-dihydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, N-vinylcaprolactam, N-vinylacetamide, N-vinylpyrrolidone, acrylonitrile, tetrahydrofurfuryl acrylate, acrylamide, mono- or di-N-alkyl substituted acrylamides, glyceryl methacrylates, and combinations thereof. Preferred polar monomers include 2-hydroxyethyl methacrylate (HEMA), N-vinylpyrrolidone, N-vinylacetamide, methacrylamide, and mixtures thereof.

[0054] In some embodiments, the aqueous reaction mixture comprises at least 0.5%, 1%, 2%, 10%, 20%, 25%, 30%, 40%, or even 50% hydrophilic monomers relative to the total monomers by weight. In some embodiments, the aqueous reaction mixture comprises up to 55%, 60%, 70%, 80%, 90%, or even 95% hydrophilic monomers relative to the total monomers by weight.

[0055] In some embodiments, the aqueous reaction mixture comprises a (meth)acrylamide epoxide monomer, i.e., a (meth)acrylate monomer with an epoxide substituent. Exemplary (meth)acrylamide epoxide monomers include glycidyl methacrylate and glycidyl acrylate.

[0056] In some embodiments, the aqueous reaction mixture comprises at least 0.1%, 0.5%, 1%, 1.5%, 2%, or even 2.5% (meth)acryloyl epoxide monomer relative to the total monomers by weight. In some embodiments, the aqueous reaction mixture comprises up to 20%, 15%, 10%, 5%, or even 3% (meth)acryloyl epoxide monomer relative to the total monomers by weight.

[0057] In some embodiments, the aqueous reaction mixture comprises a monofunctional olefinic unsaturated monomer having a poly(epoxide) group. Such poly(epoxide) monomers may have the following formula:

[0058] ZQ-(CH(R 5 )—CH2-Q) m -R 6 III

[0059] Where Z represents the polymerizable unsaturated olefinic moiety, and R... 5 It is H or a C1 to C4 alkyl group, R 6It is an H, C1 to C4 alkyl group, aryl group or combination thereof, and m is 2 to 100, preferably 5 to 20, and Q is selected from -O-, -NR. 1 —、—CO2— and —CONR 1 The divalent linker group.

[0060] In one embodiment, the poly(epoxyalkylene) group is a poly(ethylene oxide) (co)polymer. In another embodiment, the side poly(epoxyalkylene) groups are poly(ethylene oxide-co-propylene oxide) copolymers. Such copolymers can be block copolymers, random copolymers, or gradient copolymers.

[0061] The useful olefinic unsaturated moiety Z of the monomer may include:

[0062]

[0063] Where R 3 It is H or -CH3 and r=1-10.

[0064] Monomers having poly(epoxide) groups can be prepared, for example, by reacting a monofunctional or difunctional epoxy (co)polymer (which is generally commercially available) with a reactive olefinic unsaturated compound (e.g., acrylate). The functional groups of the end-capped poly(epoxide) may include hydroxyl groups, amine groups, and carboxyl groups. Various reactive olefinic unsaturated compounds, such as acrylate derivatives, can be used, including but not limited to (meth)acrylic acid, (meth)acryloyl chloride, (meth)acrylic anhydride, and ethyl (meth)acrylic acid 2-isocyanate. Preferably, the monomer is prepared by reacting a monofunctional or difunctional epoxy (co)polymer with (meth)acrylic anhydride. Typically, 100% conversion to a monosubstituted product is obtained by combining stoichiometric amounts of the olefinic unsaturated reactant with a monofunctional epoxy (co)polymer (such as a monohydroxyl-terminated epoxy (co)polymer).

[0065] Examples of suitable monofunctional poly(epoxide) monomers include poly(ethylene oxide)(meth)acrylate, poly(propylene oxide)(meth)acrylate, poly(ethylene oxide-propylene oxide)(meth)acrylate, and combinations thereof. Such monomers preferably include a non-reactive end group, such as (C1-C4)alkoxy, aryloxy (e.g., phenoxy), and (C1-C4)alkylaryloxy. These groups can be linear or branched. These monomers can have a wide range of molecular weights and are commercially available from sources such as Sartomer Company of Exton, Pennsylvania; Shinnakamura Chemical Co., Ltd. of Tokyo, Japan; Aldrich of Milwaukee, Wisconsin; and Osaka Organic Chemical Ind., Ltd. of Osaka, Japan.

[0066] In some embodiments, the aqueous reaction mixture is substantially free of these monomers containing poly(epoxy) groups. As used herein, substantially free means less than 10, 8, 5, 2, 1, 0.5, or even 0.1% by weight or even free of these monomers relative to the total weight of the monomers.

[0067] Aqueous reaction mixtures mean that the mixture contains water and / or a water-miscible organic solvent. In some embodiments, the water-miscible solvent is a proton-containing organic liquid, such as a lower alcohol having 1 to 4 carbon atoms, a lower glycol having 2 to 6 carbon atoms, and most preferably a lower glycol ether having 3 to 6 carbon atoms and 1 to 2 ether bonds. In some embodiments, higher glycols such as poly(ethylene glycol) may be used. Any such water-miscible organic solvent preferably does not have tertiary hydrogen atoms or other groups that would delay the polymerization of the monomer and the reaction of the monomer with the fiber. Exemplary water-miscible solvents include: methanol, ethanol, n-butanol, tert-butanol, ethylene glycol, methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, methylcarbitol, ethylcarbitol, and mixtures thereof. In some embodiments, aprotic water-miscible organic solvents, such as aliphatic esters and ketones, and sulfoxides, such as ethyl acetate, propyl acetate, butyl acetate, methoxyethyl acetate, ethoxyethyl acetate, propoxyethyl acetate, butoxyethyl acetate, triethyl phosphate, acetone, methyl ethyl ketone, methyl propyl ketone, and dimethyl sulfoxide, may also be used.

[0068] The ratio of water to organic solvent can vary, but is generally greater than 1:1 (v / v) water to organic solvent, preferably greater than 5:1, and more preferably greater than 7:1.

[0069] Typically, based on the total weight of the aqueous reaction mixture, the total concentration of monomers in the aqueous reaction mixture is in the range of at least 1, 2, 5 or even 10 wt% to at most 50, 45, 40, 30, 25, 20 or even 15 wt%.

[0070] In some embodiments, the amount of the aqueous reaction mixture is at least 30, 35, 40 or even 45 g to at most 100, 90, 80, 70, 60 or even 50 g / 100 gsm spunbond fiber.

[0071] The polymerization of the monomer reaction mixture and its reaction with spunbond fibers are initiated by irradiation.

[0072] The irradiation step involves ionizing the fiber, preferably using an ionizing electron beam or gamma radiation, to prepare free radical reaction sites, which are then used to derivatize the fiber using an aqueous reaction mixture. "Ionizing radiation" refers to radiation with a dose and energy sufficient to form free radical reaction sites in the base substrate. Ionizing radiation may include gamma rays, electron beams, X-rays, and other forms of electromagnetic radiation. In some cases, corona radiation can be sufficiently high-energy radiation. When the radiation has sufficiently high energy and is absorbed by the fiber, enough energy is transferred to the fiber, causing the chemical bonds in the fiber to break, thereby forming free radical sites on the fiber.

[0073] In the irradiation step, the fibers are exposed to a sufficient amount of ionizing radiation to form free radicals within the fibers. The chamber may contain at least one device capable of providing a sufficient dose of radiation. A single device can provide a sufficient dose of radiation, although two or more devices and / or multiple passes through a single device may be used. The fiber-containing environment includes inert gases (such as nitrogen, carbon dioxide, helium, argon, etc.) and a small amount of oxygen, which is known to inhibit free radical polymerization.

[0074] Dosage refers to the total amount of energy absorbed per unit mass. Dosage is typically expressed in kilograys (kGy). A gray is defined as the amount of radiation required to provide 1 joule of energy per kilogram of mass. The total dose received by an optical fiber depends on many parameters, including source activity, residence time (i.e., the total time the sample is irradiated), distance from the source, and attenuation caused by the cross-sectional area of ​​the material between the sources and the sample. Dosage is typically adjusted by controlling residence time, distance from the source, or both.

[0075] The total dose requirement for any given composition will vary depending on the desired monomers, fibers used, and dose rate. In one embodiment, the dose range is approximately 20 to 100 kGy. Therefore, the dose rate can be selected based on the desired characteristics of a particular composition. Dose rates are typically in the range of 0.0005 kGy / second (gamma) to 200 kGy / second (electron beam).

[0076] Electron beams are a preferred method due to their readily available commercial sources. Electron beam generators are commercially available from a variety of sources, including the ESI “ELECTROCURE” EB system from Energy Sciences, Inc. (Wilmington, Massachusetts) and the BROADBEAM EB processor from PCT Engineered Systems, LLC (Davenport, Iowa). For any given equipment and irradiated sample location, the delivered dose can be measured according to ASTM E-1275, entitled “Practice for Use of a Radiochromic Film Dosimetry System.” Various dose rates can be obtained by varying the extractor grid voltage, beam diameter, and / or distance from the source.

[0077] Other radiation sources with similar derivatization properties can be used; desired ionizing radiation sources include electron beam sources because electron beams can produce high and rapid dose delivery rates. Electron beams (e-beams) are typically produced by applying a high voltage to a point maintained at approximately 10... −6 Electrons are generated on a tungsten filament between a repulsion plate and an extractor grid within the vacuum chamber of the extractor. The filament is heated under a high current to generate electrons. These electrons are guided and accelerated by the repulsion plate and the extractor grid to a thin metal foil window. The accelerated electrons travel at speeds exceeding 10... 7 Traveling at a speed of meters per second (m / sec) and having a voltage of approximately 100 to 300 kiloelectron volts (keV), it leaves the vacuum chamber through the foil window and penetrates any material placed immediately adjacent to the foil window.

[0078] The number of electrons generated is directly related to the current. As the extractor gate voltage increases, the acceleration or velocity of the electrons drawn from the tungsten filament increases. Under computer control, electron beam processing is extremely precise, allowing electrons to be guided onto the optical fiber with precise dose and dose rate.

[0079] The temperature within the chamber is ideally maintained at ambient temperature using conventional methods. It is not desirable to be confined to any particular mechanism, but it is thought that exposing the fibers to an electron beam leads to the generation of free radical sites in the substrate, which can then react with monomers in an aqueous reaction mixture.

[0080] The total dose received by the substrate primarily affects the number of free radical sites formed, which in turn influences the extent of monomer-fiber reaction. The dose depends on numerous processing parameters, including voltage, web speed or linear speed, and electron beam current. The dose can be conveniently adjusted by controlling the linear speed (i.e., the speed at which the nonwoven substrate passes under the irradiation device) and the current supplied to the extractor grid. The target dose (e.g., < 10 kGy) can be conveniently calculated to determine the exposure by multiplying the experimentally measured coefficient (machine constant) by the beam current and dividing by the web speed. The machine constant varies as a function of the electron beam voltage.

[0081] While controlled electron beam radiation exposure depends on dwell time, the controlled dose experienced by fibers ranges from a minimum dose of about 1 kGy to a maximum practical dose of less than about 200 kGy, depending on the specific polymer. Typically, suitable gamma-ray sources emit gamma rays with energies of 400 keV or higher. Typically, suitable gamma-ray sources emit gamma rays with energies in the range of 500 keV to 5 MeV. Examples of suitable gamma-ray sources include the cobalt-60 isotope (which emits photons with energies of approximately 1.17 and 1.33 MeV in almost equal proportions) and the cesium-137 isotope (which emits photons with energies of approximately 0.662 MeV). The distance from the source can be fixed or can be varied by changing the location of the target or source. The gamma-ray flux emitted from the source typically decays by the square of the distance to the source and the duration controlled by the isotope half-life.

[0082] In this method, irradiated fibers containing free radical sites are contacted with an aqueous reaction mixture after the irradiation step, rather than simultaneously with the irradiation step. The average lifetime of the free radical sites generated in the fibers ranges from several minutes to several hours, gradually decaying to low concentrations over approximately ten hours at room temperature. Lower temperatures, such as dry ice temperatures, promote longer free radical lifetimes. Alternatively, humidification and nitrous oxide can increase the rate of substrate free radical formation by generating hydroxyl radicals.

[0083] Typically, the irradiated fibers are contacted with the aqueous reaction mixture immediately after the irradiation step. When using an electron beam, the irradiated fibers typically absorb the irradiation within 1 hour, preferably within 10 minutes.

[0084] The fibers can be contacted with the aqueous reaction mixture using techniques known in the art, including but not limited to spray coating, overflow coating, blade coating, Meyer bar coating, dip coating, and gravure printing coating.

[0085] The aqueous reaction mixture is kept in contact with the fiber for a sufficient duration to allow free radical sites to initiate polymerization with the monomer. When in contact with the monomer solution, the reaction is largely completed within 12 hours of exposure; typically, it is over 90%. Therefore, the fiber contains polymers and / or copolymers attached to the gaps, outer surface, and interior of the fiber.

[0086] Typically, the total monomer content functionalized onto the fiber can be 0.5 to 5 times the fiber weight.

[0087] Once the fibers have been in contact with the aqueous reaction mixture for the desired period of time, the polymer-functionalized fibers can be optionally rinsed to remove residual monomers and / or dried.

[0088] In optional rinsing steps, the chemically functionalized fibers are washed or rinsed once or multiple times to remove any unreacted monomers, solvents, or other reaction byproducts. Typically, the functionalized fibers are washed or rinsed up to three times using a water rinse, an ethanol rinse, a combination of water and ethanol rinses, and / or a solvent rinse (e.g., acetone, methyl ethyl ketone, etc.). When using an alcohol rinse, the rinse may contain one or more alcohols, including but not limited to isopropanol, methanol, ethanol, or any other alcohol actually used, and is an effective solvent for any residual monomers. In each rinsing step, the functionalized fibers may be rinsed through a rinsing bath or rinsing spray. In some embodiments, the rinsing solution may contain an ion buffer solution, which will reduce swelling of the resulting polymer, the amount of water retained, and also prevent the chemically functionalized nonwoven material from being weakened during this rinsing step.

[0089] In an optional drying step, the functionalized fibers are dried to remove any rinsing solution. Typically, the functionalized fibers are dried in an oven at a relatively low temperature for the desired period of time (referred to herein as "oven dwell time"). Oven temperatures are typically in the range of about 60°C to about 120°C, while oven dwell times are typically in the range of about 8 hours to about 72 hours. Any conventional oven can be used in the optional drying step. It should also be noted that in other embodiments, the drying step may be performed prior to the rinsing step to eliminate volatile components before the extraction of unreacted residues. After the optional drying step, the dried functionalized fibers can be wound into rolls for storage for future use.

[0090] In some embodiments, the mass increase of the chemically functionalized nonwoven material disclosed herein is at least 75%, 100%, 150%, 200%, or even 250%. Typically, the mass increase of the chemically functionalized nonwoven material does not exceed 300% or even 350% to maintain structural integrity.

[0091] In some embodiments, as determined in the Examples section, the surface area of ​​the chemically functionalized nonwoven materials disclosed herein is at least 1, 1.2, 1.3, or even 1.4 m². 2 Maximum 2.0, 1.8, 1.6, or even 1.5 m 2 .

[0092] The derived nonwoven materials can be manufactured using a web-forming process. In other words, in a factory, long strips of nonwoven material can be rapidly rolled into rolls using rollers, coating machines, and ovens, and then unrolled and cut into individual articles. In some embodiments, these articles can be housed within a casing, particularly for the separation or purification of water-based substances. As can be seen in the Examples section below, nonwoven materials swell when boiled in water for 1 hour. This swelling alters the dimensions of the nonwoven material, potentially causing problems during processing and / or use. As shown in the Examples section below, the dimensional changes may be non-uniform, with the change in one direction (e.g., length) being greater than the change in another direction (e.g., width). Surprisingly, this disclosure finds that the dimensional changes of spunbond nonwoven materials are minimal during boiling in water for 1 hour. In some embodiments, the percentage change in area of ​​the articles of this disclosure is less than 25%, 20%, 15%, or even 10%.

[0093] In some embodiments, the chemically functionalized nonwoven materials disclosed herein have improved ability to capture target analytes due to increased derivatization efficiency. For example, in some embodiments, the nonwoven materials of this disclosure have a binding capacity for Metanil Yellow of at least 350, 375, 400, 425, or even 450 mg / g.

[0094] In some embodiments, the chemically functionalized nonwoven materials disclosed herein can be used, for example, in filtration applications, such as filtering macromolecules from fluids. For example, the purification or separation of biological materials.

[0095] Example

[0096] Unless otherwise stated, all parts, percentages, ratios, etc., in the examples and the remainder of the instructions are by weight, and all reagents used in the examples are obtained from or available from general chemical suppliers, such as Sigma-Aldrich Company of St. Louis, Missouri, or can be synthesized by conventional methods.

[0097] The following abbreviations are used in the following examples: cm = centimeter, g = gram, gsm = gram per square meter, ghm = gram per pore per minute, hr = hour, ℃ = degree Celsius, in = inch, kV = kilovolt, lpm = liter per minute, mA = milliampere, mg = milligram, MRad = megarad, min = minute, m = meter, mm = millimeter, mM = millimole, mL = milliliter, nm = nanometer, Pa = pascal, psi = pound per square inch, ppm = part per million, oz = ounce, and sec = second.

[0098] Material

[0099]

[0100] Method for manufacturing fiber-containing spunbond (SB) nonwoven materials

[0101] Nonwoven media substrates were produced on a 0.5 m spunbond laboratory production line with a 2.5 in (6.35 cm) single-screw extruder equipped with a satellite melt pump for metering the flow rate of polymer toward the spinneret assembly. Monocomponent fibers were then produced. This process is consistent with the process described in U.S. Patent No. 6,916,752 (Berrigan et al.). The polymer melt enters the assembly, is uniformly distributed and filtered before reaching the spinneret orifice, and the filaments are extruded through the orifice.

[0102] As the polymer (nylon or PP) exits from the spinneret at the bottom of the assembly and is vertically introduced into the attenuator supplied with compressed air through a quenching zone in which cold air is injected, filaments (or fibers) are formed. The filaments are then laid on a moving collector belt to form a nonwoven web, which is held in place by vacuum until it passes through the bonding zone, where the nonwoven web is wound onto a surface winding machine. Nylon spunbond nonwovens and polypropylene spunbond nonwovens are prepared using the same equipment with different temperature settings.

[0103] Methods for manufacturing meltblown (BMF) nonwoven materials containing fibers

[0104] Nonwoven meltblown fiber webs were prepared using a conventional meltblown process, which included a 50.8 mm diameter single-screw extruder equipped with a resin drying hopper. The extruder output was fed to a depth of 10 cm. 3A rotary gear pump delivers the polymer melt to a 318 mm wide multi-row nozzle die, available under the trade name "SPUN-BLOWN" from Biax Fiberfilm Corporation (Neenah, WI). The die has 14 rows of spinnerets. The outermost rows on each side eject hot compressed air, while the middle 12 rows eject molten polymer, which is then diluted into meltblown fibers by the hot compressed air. The fibers from the nozzle array are quenched using a water spray. The fibers are collected on a flat stainless steel mesh belt collector, which is then wound into rolls with vacuum suction on the back of the belt. The center-to-center distance between the nozzle rows on the die spinneret is 1.78 mm, and the center-to-center distance between nozzles within each row is also 1.78 mm. The inner diameter of the nozzles is 0.38 mm.

[0105] The molten fiber stream was quenched using a water mist spray. The water mist was generated using high-pressure water mist nozzles supplied by Aeromist Inc. (Phoenix, AZ). The nozzles had an orifice diameter of 0.152 mm and a center-to-center distance of 38.1 mm on the stainless steel distribution tubes. Water atomizing distribution tubes were used on each side of the molten fiber stream. Deionized water was injected into the atomizing nozzles at 500 psi.

[0106] Pressure drop test

[0107] Operate the high-speed automated filter tester (8130, TSI Inc., Shoreview, MN) with particle generation and measurement disabled. Adjust the flow rate to 85 lpm and use a sample with a diameter of 5.25 in (13.34 cm). Place the sample on the lower circular pressure vent and start the tester. The pressure sensor within the device (MKSI Instruments, Inc., Andover, MA) measures the pressure drop (ΔP) (in millimeters of water).

[0108] Methods for measuring effective fiber diameter (EFD)

[0109] The EFD was calculated based on the pressure drop (measured using the “pressure drop test” described herein), thickness, and surface flow velocity of 5.3 cm / sec. The thickness of a 5.25-inch (13.34 cm) intervertebral disc sample was measured using a thickness gauge with a foot size of 5 cm x 12.5 cm at an applied pressure of 150 Pa. The effective fiber diameter (in micrometers) was calculated based on the measured pressure drop, as described in CN. The effective fiber diameter in micrometers is calculated as described in CNDavies, The Separation of Airborne Dustand Particulates, Proceedings of the Institution of Mechanical Engineers, London, IB (1952).

[0110] Scanning electron microscope (SEM)

[0111] Fiber dimensions and cross-sections were examined using a scanning electron microscope (Hitachi TM4000Plus, purchased from NCI Inc., Brooklyn Park, MN). Cross-sections were prepared by cryogenic fracturing of the sample using liquid nitrogen. A thin layer of gold was sputtered onto the sample to impart conductivity.

[0112] Actual fiber diameter (or AFD)

[0113] Optical imaging of fibers in spunbond nonwovens was performed using an optical microscope (ECLIPSE E600POL, Nikon, Tokyo, Japan) equipped with a digital camera (DMC5400, Leica Microsystems, Bloomington, Minnesota). For the conditions of interest, fiber bundles were collected below attenuators, cross-sections were prepared, and multifocal images were obtained using the optical microscope at 50x or 100x magnification (the precise magnification was selected as needed to obtain images from a single image). Fibers were then measured manually, with edge detection assisted by the relevant Leica Approval Suite X v3.0.9.19082 software (from Leica Microsystems, Bloomington, Minnesota, USA).

[0114] Electron beam (EB) derivatization process

[0115] The fibers were derivatized as follows: An aqueous reaction mixture (as described in the examples) was prepared in a 4-ounce (118 ml) tightly sealed wide-mouth flask to a total volume of 60 to 100 ml. After preparing the mixture, the flask was shaken by hand and bubbled with room-temperature nitrogen. The flask was then transferred to a nitrogen-containing glove box and left unsealed until the oxygen monitor reading in the glove box was <20 ppm.

[0116] Nonwoven material samples were prepared into 7 in x 9 in (17.8 cm x 22.9 cm) sheets and placed in 8 in x 10 in (20 cm x 25 cm) top-sealed plastic bags. The bags containing the samples were opened in a glove box and inertized with nitrogen until the glove box oxygen monitor reading was < 20 ppm. The bags were then opened, removed from the glove box, and taped onto a PET carrier web. The samples were then passed through an ElectroCure electron beam (Environment Sciences, Inc., Wilmington, MA) at a rate of 35 feet per minute (fpm). The samples were irradiated at 300 kV until the specified dose, typically 10 MRad, was reached. The resulting beam current was 55 mA.

[0117] After irradiation, the sample was removed and transferred back to the glove box. The oxygen monitor was allowed to reach <20 ppm before opening the bag. To deposit monomers and initiate polymerization, the wide-mouth flask containing the aqueous reaction mixture was hand-shaken and then poured onto the nonwoven material inside the bag. To promote wetting of the entire sample, a hand roller was rolled over the sealed bag containing the nonwoven material and the aqueous reaction mixture. After 3 hours of reaction, the sample was removed from the glove box, exposed to the atmosphere, and then placed in boiling deionized water for 1 hour to further saturate the reaction and remove residual monomers. The derivatized nonwoven material was then placed on an aluminum tray lined with polyethylene and dried overnight at room temperature, followed by further drying in a 70°C oven for 12 to 16 hours, before subsequent characterization and performance testing.

[0118] Changes in sample size after functionalization

[0119] The length and width of the functionalized sample after boiling were measured and compared with the original sample volume. The dimensional changes were expressed as area changes using the following formula:

[0120] Percentage change in area = { [(length of the sample after boiling x width of the sample after boiling) / (length of the original sample x width of the original sample)] – 1} x 100

[0121] Basis weight

[0122] Cut a known sample size (e.g., a 5.25-inch circle) from the sample and weigh it to obtain the basis weight in grams per square meter (gsm).

[0123] Weight gain assessment

[0124] The amount of monomer polymerized onto the fiber was determined by gravimetric analysis using the following equation:

[0125] Weight gain percentage = [(Final web weight - Initial web weight) / Initial web weight] x 100

[0126] surface area

[0127] The total surface area of ​​the non-derivative [9 inches (22.9 cm) x 7 inches (17.8 cm)] nonwoven material sample was calculated using the following formula:

[0128] Specific surface area = 4 / (polymer density x effective fiber diameter)

[0129] Sample surface area = specific surface area x weight of nonwoven material

[0130] Metanil's dynamic binding capability (MYDBC)

[0131] MYDBC was measured using a 47 mm scaffold loaded with functional culture medium and stacked with non-functional 0.2 μm membranes to improve flow cytometry uniformity. The value was determined by the 5% breakthrough of a 160 ppm sulfanilamide yellow solution dissolved in 140 mM sodium chloride and 50 mM phosphate. The breakthrough point was determined by turbidity measurement calibrated against the turbidity of an 8 ppm hyaluronic acid yellow solution. The flow rate was set at 930 LMH. The MYDBC value was then normalized to the weight of the chemically functionalized copolymer and reported as mg / g (weight of bonded m-phenylenediamine yellow / weight of chemically functionalized copolymer). The weight of the chemically functionalized copolymer was calculated based on the weight of the functional culture medium and the increment.

[0132] Substrate samples 1-9 (SE1-SE9)

[0133] Nylon BMF, nylon SB, and PP SB were prepared using the methods described above for preparing spunbond (SB) and meltblown (BMF) nonwoven materials. Table 1 shows the substrate properties measured on the obtained nonwoven materials, including thickness, basis weight, density, pressure drop (ΔP), effective fiber diameter (EFD), and average actual fiber diameter (AFD). Table 1 also records the basis weight of the nylon samples equivalent to polypropylene, calculated by multiplying the basis weight of the nylon sample by the density of polypropylene (0.91 g / cm³). 3 Divide by the density of nylon (1.15 g / cm³) 3 This is done to show that, taking density into account, all samples have similar quantification.

[0134] Table 1

[0135]

[0136] Compare Examples 1-4 (CE-1 to CE-4) and Examples 1-2 (EX-1 to EX-2).

[0137] Both SB and BMF type nylon substrate samples were derivatized according to the EB derivatization procedure. The aqueous reaction mixture used for functionalization contained 5 wt% MAPTAC and 6 wt% NVP aqueous solution.

[0138] Table 2 shows the sample weight before (initial) derivatization, the weight after (final) derivatization, and the corresponding weight gain percentage, indicating how much monomer is polymerized into the nonwoven material.

[0139] Table 2 also records the length and width of the derivatized samples before drying after boiling in water for 1 hour. The percentage change in area was determined by multiplying this length and width by the initial length and width before derivatization of the nonwoven material. Since the initial nonwoven material was 9 inches x 7 inches, some samples showed greater dimensional changes than others. Table 2 also records the surface area of ​​each nonwoven material sample. Comparing the peak area change percentage by surface area, compared to EX-1 and EX-2, the peak area change percentage for CE-1 through CE-4 decreased sharply with increasing surface area.

[0140] Table 2

[0141]

[0142] As shown in Table 2, compared with meltblown nonwoven materials CE-1 to CE-4, spunbond nonwoven materials EX-1 and EX-2 generally exhibit better dimensional stability and higher weight gain. Furthermore, EX-1 and EX-2 show a higher percentage weight gain compared to CE-1, despite CE-1 having a higher surface area due to its smaller fiber diameter.

[0143] Compare Examples 5 to 8 (CE-5 to CE-8)

[0144] The nonwoven media containing PP SB was derivatized according to the EB derivatization procedure. The aqueous reaction mixture used for functionalization contained 5 wt% MAPTAC, 6 wt% NVP, and 2 wt% GMA aqueous solution. GMA was added to the formulation to improve the surface wettability of polypropylene.

[0145] The samples CE-5 to CE-8, as well as EX-1 and EX-2, were evaluated, and the results are shown in Table 3. Table 3 shows the sample weights before (initial) and after (final) derivatization, along with the corresponding percentage weight gain. Table 3 also records the surface area and average MYDBC of the three different samples. Comparing the binding capacity of acetaminophen yellow (MYDBC) with the percentage weight gain in Table 3 indicates that nylon-containing nonwoven materials have more monomers derivatized into nonwoven material samples, and these samples show improved binding capacity for acetaminophen yellow.

[0146] Table 3

[0147]

[0148] Examples 3 to 6 (EX-3 to EX-6)

[0149] Substrate SE6 was derivatized using the derivatization formulations disclosed in Table 4, following the EB derivatization procedure. Table 4 shows the sample weights before (initial) and after (final) derivatization, along with the corresponding percentage weight gain. Table 4 also records the length and width of the derivatized samples before drying after boiling in water for 1 hour. MYDBC analysis was also performed on the samples, and the results are shown in Table 4.

[0150] Table 4

[0151]

[0152] As shown in Table 4, as in EX-3 and EX-4, the functionalization of spunbond nylon nonwoven materials exhibits consistent scalability, with double the monomer content resulting in a doubled weight gain percentage. All samples in Table 4 demonstrate good dimensional stability and high binding to m-amino yellow.

[0153] It is foreseeable that modifications and alterations to this invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. This invention should not be limited to the embodiments set forth in this application for illustrative purposes. In the event of any conflict or difference between the disclosure in this written specification and any document incorporated herein by reference, the written specification shall prevail.

Claims

1. A chemically functionalized nonwoven material, comprising: A spunbond nonwoven material comprising multiple homogeneous fibers, wherein the multiple homogeneous fibers comprise nylon, and wherein at least a portion of the multiple homogeneous fibers are chemically functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

2. The chemically functionalized nonwoven material according to claim 1, wherein the aqueous reaction mixture is substantially free of poly(alkylene oxide) monomers.

3. The chemically functionalized nonwoven material according to any one of the preceding claims, wherein the nylon comprises nylon 6; nylon 6,6; nylon 1,6; nylon 11; nylon 12; nylon 4,6; nylon 4; nylon 1,4; nylon 510; nylon TMDT; or combinations thereof.

4. The chemically functionalized nonwoven material of any of the preceding claims, wherein, The aminoalkyl (meth)acryloyl monomer is an amino (meth)acrylate or amino (meth)acrylamide of formula I or a quaternary ammonium salt thereof. (I) Where R 1 It is hydrogen or methyl, preferably methyl; L is -O- or -NH-; and Y is alkylene and R 2 For (i) independently hydrogen or alkyl or (ii) two R 2 The groups, together with the nitrogen atoms to which they are attached, can form aromatic, partially unsaturated, or saturated heterocyclic groups, and optionally, said heterocyclic groups are fused with an aromatic, partially unsaturated, or saturated second ring.

5. The chemically functionalized nonwoven material according to any one of the preceding claims, wherein the aqueous reaction mixture further comprises a hydrophilic monomer.

6. The chemically functionalized nonwoven material according to claim 5, wherein the hydrophilic monomer comprises at least one of the following monomers: 2-hydroxyethyl methacrylate (HEMA), 2-ethoxyethyl methacrylate (2-EOEMA), 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2,3-dihydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, N-vinylcaprolactam, N-vinylacetamide, N-vinylpyrrolidone, acrylonitrile, tetrahydrofurfuryl acrylate, acrylamide, mono- or di-N-alkyl substituted acrylamide, glyceryl methacrylate, and combinations thereof.

7. The chemically functionalized nonwoven material according to any one of the preceding claims, wherein the aqueous reaction mixture further comprises a (meth)acryloyl epoxide monomer.

8. The chemically functionalized nonwoven material according to claim 7, wherein the (meth)acryloyl epoxide monomer comprises at least one of the following: glycidyl methacrylate or glycidyl acrylate.

9. A nonwoven material comprising a chemically functionalized nonwoven material according to any one of the preceding claims.

10. A filter medium comprising a chemically functionalized nonwoven material according to any one of claims 1 to 8.

11. A method for preparing chemically functionalized nonwoven materials, the method comprising: (i) Providing a spunbond nonwoven material, wherein the spunbond nonwoven material comprises a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprises nylon; and (ii) Contacting the spunbond nonwoven material with an aqueous reaction mixture, the aqueous reaction mixture comprising: Aminoalkyl (meth)acryloyl monomers; Optionally, hydrophilic monomers; and Optionally, (meth)acryloyl epoxide monomer; and (iii) Exposing the spunbond nonwoven material to radiation.

12. The method of claim 11, wherein the spunbond nonwoven material has an effective fiber diameter of at least 5 micrometers and at most 25 micrometers.

13. The method according to any one of claims 11 to 12, wherein the spunbond nonwoven material has a basis weight of at least 50 g / m² and at most 250 g / m².

14. The method according to any one of claims 11 to 13, wherein a 9-inch (22.9 cm) x 7-inch (17.8 cm) sheet of the spunbond nonwoven material has a surface area of ​​at least 1 m². 2 And at most 2 m 2 .

15. The method according to any one of claims 11 to 14, wherein the chemically functionalized nonwoven material has a weight gain of at least 100% and at most 350% compared to the spunbond nonwoven material.

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