Grafted articles derived from porous polymer fibers and methods thereof

Abstract

A process for producing an article and the article itself are described. The process includes (i) providing a porous polymer fiber, each porous polymer fiber having an outer main surface and a plurality of pores, at least a portion of which open to the outer main surface and extend from the outer main surface to the inner portion of the porous polymer fiber, and at least a portion of which are fluid-communicating; (ii) contacting the porous polymer fiber with a polymerizable solution; and (iii) exposing the porous polymer fiber to a controlled amount of ionizing radiation to form a grafted article. The grafted article may include a nonwoven fabric and includes porous polymer fibers, each polymer fiber having an outer main surface and a plurality of pores, at least a portion of which open to the outer main surface and extend from the outer main surface to the inner portion of the porous polymer fiber, and at least a portion of which are fluid-communicating; and a plurality of polymer chains extending from the outer main surface of the porous polymer fiber.

Description

[Technical Field]

[0001] Disclosed herein is a process for producing a grafted article comprising a plurality of porous polymer fibers from which a plurality of polymer chains extend. For example, such an article that may be used in a nonwoven fabric substrate is described. [Overview of the project]

[0002] Often, articles are manufactured with a given polymer type for cost and / or ease of processing. However, this first polymer may not be ideal from a usage standpoint because it lacks the required properties. Therefore, a second polymer may be grafted onto the first polymer. Polymer grafting by electron beam (EB) irradiation is one method of grafting polymers onto relatively inert materials such as polyolefins. However, sometimes the grafting efficiency is low. Therefore, there is a desire to improve the grafting rate.

[0003] In one embodiment, grafted fibers are discussed. The grafted fibers include (b) a porous polymer fiber having an outer main surface and a plurality of pores, at least a portion of which open to the outer main surface and extend from the outer main surface to the inner portion of the porous polymer fiber, and at least a portion of which are in fluid communication with the pores, and (b) a plurality of polymer chains extending from the outer main surface of the porous polymer fiber.

[0004] In another embodiment, grafted nonwoven articles are discussed. The grafted nonwoven articles include a nonwoven substrate, the nonwoven substrate comprising (a) a plurality of porous polymer fibers, each porous polymer fiber having an outer main surface and a plurality of pores, at least a portion of which open to the outer main surface and extend from the outer main surface to the inner portion of the porous polymer fiber, and at least a portion of which which are in fluid communication; and (b) a plurality of polymer chains extending from the outer main surface of the porous polymer fibers.

[0005] In one embodiment, a method for producing grafted fibers is disclosed. The method includes (i) providing a porous polymer fiber having an outer main surface and a plurality of pores, at least a portion of which open to the outer main surface and extend from the outer main surface to the inner portion of the porous polymer fiber, and at least a portion of which which are fluid-communicating; (ii) contacting the porous polymer fiber with a polymerizable solution; and (iii) exposing the porous polymer fiber to a controlled amount of ionizing radiation to form grafted fibers.

[0006] In another embodiment, a method for producing a grafted nonwoven article is disclosed. The method includes (i) providing a nonwoven substrate comprising a plurality of porous polymer fibers, each porous polymer fiber having an outer main surface and a plurality of pores, at least a portion of which open to the outer main surface and extend from the outer main surface to the inner portion of the porous polymer fiber, and at least a portion of which which are in fluid communication; (ii) contacting the nonwoven substrate with a polymerizable solution; and (iii) exposing the nonwoven substrate to a controlled amount of ionizing radiation to form a grafted article.

[0007] The above summary of the invention is not intended to describe each embodiment. Details of one or more embodiments of the invention are also described below. Other features, purposes, and advantages will become apparent from the detailed description of the invention and the claims. [Brief explanation of the drawing]

[0008] The embodiments described herein are illustrative and not limiting, as shown in the accompanying drawings.

[0009] [Figure 1] This is a scanning electron microscope (SEM) image of nonwoven fabric 2.

[0010] [Figure 2] This is the SEM image of Comparative Example 2.

[0011] [Figure 3] It is the SEM image of Example 2.

Mode for Carrying Out the Invention

[0012] In the terms used in this specification, "a", "an" and "the" are used interchangeably and mean one or more; and "and / or" is used to indicate that one or both of the described instances may occur. For example, A and / or B includes (A and B) and (A or B).

[0013] The term "filament" as used in this specification refers to a continuous, elongated strand that is typically longer than 6 inches.

[0014] The term "open celled porous structure" as used in this specification with respect to the structure of a fiber refers to a fiber having a plurality of pores, at least some of which are connected to adjacent pores, such that a fluid can pass from one major surface of a portion of the fiber to the opposite major surface of the fiber.

[0015] The term "microfibril" as used in this specification refers to a portion of the porous structure of a fiber having fibrils with dimensions less than 1 micrometer in each dimension.

[0016] The term "lamella" as used in this specification refers to the crystalline portion of the semi-crystalline polymer material of a fiber.

[0017] The term "continuous" as used in this specification with respect to a fiber refers to a fiber having a length with a longest dimension exceeding 1 centimeter.

[0018] The term "semi-crystalline" as used in this specification refers to a polymer that forms crystalline domains in addition to an amorphous phase upon solidification, and further exhibits a melting peak upon heating and a crystallization peak upon solidification when measured by differential scanning calorimetry (DSC).

[0019] As used herein with respect to fibers, the term "porosity" refers to a measurement of the voids within a fiber, determined by solvent absorption, for fibers having an open porous structure. One such solvent absorption method is described in the Test Methods section of U.S. Provisional Patent Application No. 63 / 422,139.

[0020] In this specification, the term "porosity" as used with respect to nonwoven fiber webs refers to the total volume of voids between individual fibers in the web, and is determined by measuring the solidity of the nonwoven fiber web and subtracting that solidity from 100. Thus, the solidity represents the proportion of the total volume of the nonwoven fiber web that is occupied by fibers. The solidity is determined by dividing the measured bulk density of the nonwoven fiber web by the density of the fibers. The bulk density of the web can be determined by first measuring the weight of the web (e.g., the weight of a 10cm × 10cm section). By dividing the measured web weight by the web area, the basis weight is obtained, which is g / m². 2 The thickness of the web can be measured by obtaining a 135 mm diameter disc of the web (e.g., by die-cutting), placing a 100 mm diameter 230 g weight in the center of the web, and measuring the web thickness. The bulk density of the web is determined by dividing the basis weight of the web by the web thickness, and is expressed as g / m². 3 It is reported as follows: The solidity ratio is determined by dividing the bulk density of the nonwoven fiber web by the density of the material (e.g., polymer) that makes up the fibers of the web. The density of the bulk polymer can be measured by standard means if the supplier does not specify the material density. The solidity ratio is a dimensionless ratio and is usually reported as a percentage.

[0021] As used herein, the term "thermoplastic" refers to a polymer that flows when heated well above its glass transition temperature and solidifies when cooled. In contrast, "thermosetting" refers to a polymer that permanently solidifies upon curing and does not flow when subsequently heated. Thermosetting polymers are typically crosslinked polymers.

[0022] As used herein, "(meth)" refers to the possibility that the compound may be methylated. For example, (meth)acrylate includes both acrylate and methacrylate, and (meth)acrylamide includes both acrylamide and methacrylamide.

[0023] Furthermore, in this specification, ranges indicated by endpoints include all numerical values ​​encompassed within that range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0024] Furthermore, in this specification, the phrase "at least one" includes all numbers greater than or equal to 1 (for example, 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.).

[0025] In this specification, "including at least one of A, B, and C" means element A alone, element B alone, element C alone, A and B, A and C, B and C, or any combination of all three.

[0026] This application relates to grafted porous polymer fibers. These grafted fibers can be used in nonwoven fabrics and have been shown to have improved grafting yields.

[0027] The porous polymer fibers disclosed herein include a plurality of pores. At least a portion of the pores open along the outer main surface of the fiber and extend into the interior of the fiber. At least a portion of the pores within the fiber are axially (d) relative to the fiber. a ) and / or radial (d r ) is in fluid communication with the . Figure 1 shows an SEM image of the outer portion of a porous fiber taken from the nonwoven fabric 2 in the example section. Figure 1 shows a fiber 10 having multiple pores 15 which extend into the interior of the fiber.

[0028] Porous polymer fibers (also referred to herein as porous fibers) can be made from polymers such as polyolefins, for example, polypropylene (PP), polyethylene (PE), polymethylpentene (PMP) or polybutene-1; polyoxymethylene (POM); vinylidene fluoride (PVDF); or copolymers thereof. In some cases, each porous fiber may contain a blend of at least two polymers, for example, a blend of a first PP and a second PP. In some cases, one PP is preferred, or two or more (e.g., different) PPs are preferred. For example, continuous fibers may contain PP with a number-average molecular weight (Mn) of at least 250,000;275,000;300,000;325,000;350,000;375,000; or 400,000 g / mol, and at most 800,000;775,000;750,000;725,000;700,000;675,000;650,000;625,000;600,000;575,000;550,000;525,000;500,000;475,000;450,000; or 425,000 g / mol. Porous fibers may include polypropylene (PP) with number-average molecular weights ranging from 250,000 g / mol to 800,000 g / mol (including endpoints). Exemplary PPs include polypropylene available from TotalEnergies Petrochemicals & Refining USA, Inc. (Houston, TX) under trade names "PPH3264" and "PPH3766".

[0029] Suitable crystalline thermoplastic polypropylene homopolymer resins are available from TotalEnergies Petrochemicals & Refining USA, Inc. (Houston, TX), and include, for example, Homopolymer Polypropylene 3281, 3274, PPH3060, 3273, 3272, 3371, PPH4022, PPH4069, 3462, 3571, 3662, M3661, 3766, 3865, and 3860. Other suitable polypropylene homopolymers are available from Lyondel-Basell Industries (Pasadena, TX) under the trade name "PRO-FAX," and include, for example, PRO-FAX 1280, PRO-FAX 814, PRO-FAX 1282, PRO-FAX 1283, or other trade names such as ADFLUEX X500F, ADSYL 3C30F, HP403G, and TOPPYL SP2103. Additional suitable polypropylene homopolymers are available from INEOS Olefins & Polymers, USA (Carson, CA), such as INEOS H01-00, INEOS H02C-00, INEOS H04G-00, and INEOS H12G-00. Other suitable polypropylene homopolymers are available from Braskem Chemical and Plastics Company (LaPorte, TX), such as F008, F013M, FF026, and FF030F2. Even more suitable polypropylene homopolymers are available from Exxon-Mobil Chemical Co. (Spring, TX), such as PP1024E4, PP2252E3, PP4292E1, PP4612E2, and PP4792.

[0030] Suitable crystalline thermoplastic polyethylene (PE) homopolymer resins are available from Exxon-Mobil Chemical Co. (Spring, TX), for example, HDPE6908. Suitable polyethylene homopolymers are also available from TotalEnergies Petrochemicals & Refining USA, Inc. (Houston, TX), for example, high-density polyethylenes HDPE56020, HDPE55060, HDPE5802, HDPE51090, and HDPE5502. Other suitable polyethylene homopolymers are available from Braskem Chemical and Plastics Company (LaPorte, TX), such as HF0144, HF0150, HF0147, and FH35, and polyethylene polymers are available from NOVA Chemicals Corporation (Calgary, AB, Canada), such as SUPRASS HPs167-AB, HPs267-AB, HPs667-AB, SCLAIR19E, SCLAIR99L, and NOVAPOL HB-L354-A.

[0031] In some embodiments, the polymer resin may also include one or more poly(methyl)pentene (PMP) copolymer resins. Preferred grades of PMP copolymer resins with low linear or branched α-olefin copolymer content are available from Mitsui Chemicals (Minato-ku, Tokyo, Japan) under the general trade name "TPX," and include, for example, resin grades DX470, RT18, DX820, and DX845.

[0032] Suitable crystalline thermoplastic polybutene-1 (PB-1) homopolymer resins are available from Lyondel-Basell Industries (Pasadena, TX), including, for example, Toppyl PB0110M, Toppyl PB8640M, Toppyl PB8310, and Toppyl PB8340M.

[0033] The porous fibers described herein include a plurality of pores that interrupt the outer surface of the porous fiber and extend inward into the fiber. In one embodiment, assuming a circular cross-section, the pores have an average pore diameter of at least 5, 10, 15, 20, 35, or 30 nm and a maximum of 50, 60, 80, 100, 125, 150, 200, 300, 400, or 500 nm along the outer surface of the porous fiber. The pore diameter can be determined using techniques known in the industry, such as scanning electron microscopy (SEM).

[0034] Porous fibers have multiple pores. These multiple pores result in the fiber having a higher surface area. For example, in one embodiment, porous polymer fibers have at least 5, 10, 15, 20, 35, 30, or 40 m², determined by BET (Brunauer Emmet Teller) nitrogen adsorption. 2 It has an average surface area per gram.

[0035] In one embodiment, the porous fibers have an open porous structure, typically with a fiber porosity of at least 5, 0, 12, 15, 17, 20, 25, 30, 35, 40, or 45 volume%, and up to 50, 55, 60, 65, 70, 75, or 80 volume%.

[0036] In one embodiment, the porous fibers have an average diameter of at least 6, 8, 10, 12, 15, 20, or 25 micrometers. Typically, the porous fibers have an average diameter of less than 200, 100, or 50 micrometers. The fiber diameter may be determined using techniques known in the art, such as scanning electron microscopy (SEM).

[0037] In one embodiment, the porous fibers described herein are manufactured using the process described in U.S. Provisional Patent Application No. 63 / 422139 (Zhou et al.), the details of which are incorporated herein by reference. Briefly, a polymer material (e.g., a crystalline thermoplastic material) is extruded under well-controlled process conditions under air cooling to form fibers. The rows of crystalline phases are oriented in the direction of the fibers. As the fibers are stretched and exposed to a cold-heat-relaxation sequence, pores are formed inside the fibers. Figure 1 shows a fiber manufactured according to the process disclosed in U.S. Provisional Patent Application No. 63 / 422139. Figure 1 also shows a number of microfibers 12 extending between opposing lamellar microstructures 14. Together, the microfibers 12 and the lamellar microstructures 14 define the voids 15 of the porous fiber 10. The size of the microfibers 12 may vary, typically having at least one dimension of 1 micrometer or less in length. In some cases, lamellar microstructures tend to have a non-row ordered configuration, but they are deformed during elongation, resulting in a curved lamellar microstructure.

[0038] In one embodiment, porous fibers are used in a nonwoven fabric substrate. As used herein, "nonwoven fabric" generally refers to a fiber web or material characterized by the entanglement or point bonding of multiple fibers, where the fibers are overlapped but not in a recognizable, regular arrangement like that of a knitted fabric.

[0039] In one embodiment, at least 50, 60, 70, or 75% by weight of the nonwoven substrate is composed of porous polymer fibers. In one embodiment, up to 99, 98, 95, 90, 85, or 80% by weight of the nonwoven substrate is composed of porous polymer fibers. In some embodiments, the nonwoven substrate does not contain any fibers other than porous fibers.

[0040] In one embodiment, the nonwoven fabric substrates described herein may be prepared as continuous fiber strands from melting processes known in the art, such as melt-blown processes and spunbonding processes. In the melt-blown process, a nonwoven fiber web is formed by extruding a fiber-forming material (e.g., a polyolefin-containing polymer) through one or more orifices to form filaments, attenuating the filaments into individual discontinuous fibers by contacting them with air or other attenuating fluid, and then collecting layers of the drawn individual discontinuous fibers. In the spunbonding process, molten fiber-forming material is extruded from multiple thin, usually circular, capillaries of a spinneret, and the diameter of the extruded fibers is rapidly reduced, for example, by drawing and / or other well-known spunbonding mechanisms. The spunbonded fibers are collected on a surface to form a web.

[0041] Alternatively, to form the nonwoven fabric substrates specified herein, short porous fibers may be prepared or cut from continuous strands and bonded to each other using secondary bonding processes known in the art. Such bonding processes include bonded carding, through-air bonding, and pattern roll bonding. In the bonded carding process, the small diameter fibers specified herein are fed into a fiberizing unit / picker that separates the fibers. The fibers are then passed through a combining or carding unit to further break down the stapled fibers and orient them in the machine direction to form a machine-oriented nonwoven web. After the web is formed, it is further bonded by one or more bonding methods. One bonding method is powder bonding, in which a powdered adhesive is dispersed throughout the web, and then the web and adhesive are heated and activated, usually with hot air. Another bonding method is pattern bonding, in which a heated calender roll or ultrasonic bonding device is used to bond the fibers together, usually in a localized bonding pattern through the web, or the web may be bonded throughout if desired. When using two-component staple fibers, through-air bonding apparatus is particularly advantageous in many applications. Another bonding process is the wet-laid process, similar to conventional papermaking processes, in which the small-diameter fibers described herein, along with any other fibers and binders, are suspended in a fluid and deposited onto a screen or porous surface, after which the fluid is removed.

[0042] In yet another embodiment, small-diameter fibers can be produced using hydro-entungling technology, in which a high-speed water jet is used to wrap or tie individual fibers together during the web joining process. Such technology is known in the art; see, for example, U.S. Patents 7,981,336, 6,110,588, and 5,207,970.

[0043] In one embodiment, the porosity of the nonwoven fiber web may exceed 90, 91, 92, 93, 94, or 95%. Since the porosity of the nonwoven fiber web is determined by measuring the solidity and subtracting it from 100, the measured solidity of the nonwoven fiber web may be less than 10, 9, 8, 7, 6, or 5%.

[0044] Advantageously, nonwoven fabric substrates containing multiple porous polymer fibers can be produced by a roll-to-roll method, in other words, by continuous processing of the substrate along a roller-based processing line.

[0045] The porous fibers (or porous fibers in the form of a nonwoven fabric substrate) described herein are grafted with polymers.

[0046] Typically, for grafting, porous fibers, or nonwoven fabrics containing porous fibers, are brought into contact with a polymerizable composition containing monomers for grafting. While not intended to be limited to theory, it is believed that the monomers should be diffusible or small enough in size so that they can diffuse into the pores of the porous fibers.

[0047] In some embodiments, the monomer for grafting includes a functional moiety. In one embodiment, a monomer of formula I, comprising an ethylenically unsaturated moiety and a functional moiety, is used to graft the functional moiety onto the surface of a porous fiber: [ka] [Wherein, X is H or CH3, and Y contains a functional moiety]. As used herein, the functional moiety refers to a group that introduces new functionality into the porous fiber. The functional moiety is a group that provides a specific purpose. For example, the functional moiety can provide a site for further reaction, impart properties such as wettability to an article, or provide a site for interaction with a target compound. The functional moiety is located at the end of the grafted polymer, either as an end group or within a side chain, depending on polymer chemistry. In one embodiment, the monomer introduces an ionic moiety, such as a sulfonic acid group, an amino group, a quaternary ammonium group, or a combination thereof.

[0048] One such ionic monomer is of formula II or a salt thereof:

Chemical formula

[0049] In another embodiment, a porous fiber or a nonwoven substrate containing the porous fiber is treated to include a quaternary ammonium functional group, i.e., -N + R 2 R 3 R 4 M - (M - is a counterion group, often a halide (e.g., Cl - ), sulfate, phosphate, nitrate, etc.). In some embodiments, the R 2 , R 3 , and R4 In other embodiments, R 2 , R 3 , and R 4 One of them is methyl, and the remaining two are alkyl groups having 2 to 18, 2 to 10, 2 to 6, or 2 to 4 carbon atoms. In other embodiments, R 2 , R 3 , and R 4 Two of these are methyl atoms, and the remaining one is an alkyl group having 2 to 18, 2 to 10, 2 to 6, or 2 to 4 carbon atoms. In yet another embodiment, R 2 , R 3 , and R 4 At least two of these atoms, together with the nitrogen atom to which they are bonded, form a heterocyclic group. The heterocyclic group contains at least one nitrogen atom and may contain other heteroatoms such as oxygen or sulfur. Examples of heterocyclic groups include, but are not limited to, piperidinyl and morpholinyl. The heterocyclic group may be fused with an additional ring such as benzene, cyclohexene, or cyclohexane.

[0050] In one embodiment, for example, a quaternary ammonium salt of an aminoalkyl (meth)acryloyl monomer, such as formula (III), is used: [ka] [In the formula, R 1 R is H or CH3; L is O or NH; and Z is a straight-chain or branched alkylene as described above. 5 , R 6 , and R 7 M is independently aryl or alkyl, preferably C1-C4 alkyl; - It is a counter anionic group, and is often found in halides (e.g., Cl - These include sulfates, phosphates, and nitrates.

[0051] Examples of quaternary salts of aminoalkyl(meth)acryloyl monomers of formula (III) include, but are not limited to, (meth)acrylamidealkyltrimethylammonium salts (e.g., 3-methacrylamidepropyltrimethylammonium chloride and 3-acrylamidepropyltrimethylammonium chloride) and (meth)acryloxyalkyltrimethylammonium salts (e.g., 2-acryloxyethyltrimethylammonium chloride, 2-methacryloxyethyltrimethylammonium chloride, 3-methacryloxy-2-hydroxypropyltrimethylammonium chloride, 3-acryloxy-2-hydroxypropyltrimethylammonium chloride, and 2-acryloxyethyltrimethylammonium methyl sulfate). Such monomers having a quaternary ammonium group of formula (III) can be grafted directly onto the surface of a nonwoven fabric substrate, or an aminoalkyl(meth)acryloyl monomer having a primary, secondary, or tertiary amine group may be grafted and then converted to a quaternary ammonium group by alkylation. The manufacture of such anion-exchange nonwoven fabrics is described in U.S. Patent No. 8,328,023 (Weiss et al.).

[0052] In one embodiment, the monomers for grafting are N-vinylpyrrolidone, 4-hydroxybutyl methacrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, (meth)acrylamide, N-methylolacrylamide, poly(ethylene glycol) mono(meth)acrylate, poly(propylene glycol) mono(meth)acrylate, N-isopropylacrylamide, N-vinylcaprolactam, N-vinylformamide, N-vinyl-N-methylacetamide, 1-ethenyl-3-ethylurea, N-acryloylmorpholine, diethyl (meth)acrylamide, dimethyl (meth)acrylamide, glycerol mono(meth)acrylate, and tetrahydrofurfuryl acrylate.

[0053] Ionizing radiation can be used to initiate the grafting of monomers or combinations of monomers onto the surface of porous polymer fibers.

[0054] The irradiation step involves irradiating the substrate surface with ionizing radiation to generate free radical reaction sites on the surface, followed by the grafting of graft monomers or combinations of graft monomers thereon. “Ionizing radiation” means irradiation with electron beams, gamma rays, and X-rays having sufficient dose and energy to form free radical reaction sites on the surface of the porous fibers. The radiation, when absorbed by the porous fibers, has sufficient energy to break the chemical bonds of the porous fibers and generate free radical sites. The free radical sites on the surface of the porous fibers react with the carbon-carbon double bonds of the graft monomers, allowing for further addition of graft monomers via free radical addition (or chain) polymerization. Other reactions are also possible. For example, if the graft monomers and porous fibers are in contact during the irradiation step, free radicals may be generated in both the monomers and the porous fibers. As is known in the art, free radicals in the graft composition initiate polymerization of the graft monomers, and the resulting monomers, oligomers, and polymers may have active free radical species that can bind to the free radical sites on the porous fibers.

[0055] In this specification, ionizing radiation is selected from electron beams, X-rays, and / or gamma rays. Since these radiation sources can penetrate solids, porous fibers do not act as a mask during irradiation. This is particularly advantageous when surface-treating nonwoven substrates containing multiple porous fibers with complex pore networks. The radiation source can be selected depending on the application. For example, electron beams use accelerated electrons, while gamma-ray irradiation uses gamma rays produced by radioactive isotopes in a continuous exposure mode. Therefore, gamma rays have higher penetration than electron beams in irradiation and are suitable for irradiating denser materials. Because electron beams are power-driven, they can provide significantly higher dose rates and thus significantly shorter required times. Gamma rays can treat dense and bulky materials, while electron beams may be more suitable for continuous or semi-continuous web-based processes. X-rays are similar to gamma rays, but the radiation is produced in different ways. Gamma rays are produced by radioactive decay, while X-rays are bremsstrahlung radiation produced by colliding accelerated electrons with a metal target. Generally, X-ray tubes emit wavelengths slightly longer and photon energies lower than gamma-ray sources. Depending on the density of the product, the packaging of the product, and / or the desired processing mode, one irradiation method may be preferred over another. For example, electron beam irradiation provides a significantly higher dose rate and therefore requires significantly shorter irradiation times than gamma-ray irradiation. Thus, electron beam irradiation is more suitable than gamma-ray irradiation for continuous or semi-continuous web-based processes. On the other hand, gamma-ray irradiation may be more suitable for batch processes and surface treatment of large objects or large-volume assemblies of objects.

[0056] In the irradiation process, porous fibers, or nonwoven fabric substrates containing porous fibers, are exposed to ionizing radiation in a chamber. The chamber may contain at least one source capable of supplying a sufficient dose of radiation. While a single source is usually sufficient to supply a sufficient dose of radiation, two or more sources, and / or multiple passes through a single source, may be used. Dose is the total amount of energy absorbed per unit mass. Dose is generally expressed in kilograys (kGy). A gray is defined as the amount of radiation required to supply one joule of energy per kilogram of mass.

[0057] In one embodiment, porous fibers (or nonwoven fabrics containing porous fibers) are first exposed to a controlled amount of ionizing radiation and then brought into contact with graftable monomers. Alternatively, porous fibers (or nonwoven fabrics containing porous fibers) are first brought into contact with graftable monomers and then exposed to a controlled amount of ionizing radiation to produce grafted fibers.

[0058] Typically, grafting of porous fibers occurs over a large portion of the exposed surface of the porous fibers. In one embodiment, multiple polymer chains extending from the outer main surface of a porous polymer fiber cover, on average, at least 50, 60, 70, or 80% of the surface of the multiple porous polymer fibers.

[0059] In one embodiment, a plurality of porous polymer fibers have a first average fiber diameter, and a plurality of polymer chains extending from the outer main surface of the porous polymer fibers result in a second average fiber diameter, the second average fiber diameter being at least 10, 20, or 30% larger than the first average fiber diameter.

[0060] While not intended to be limited to theory, the large surface area provided by porosity is thought to allow graft growth to progress into the interior of the porous fibers, enabling high graft yields even with small pore sizes. In one embodiment, the porous fibers obtain a weight increase of at least 100, 150, or 200%.

[0061] In one embodiment, the grafted porous fibers disclosed herein are used in a nonwoven fabric substrate to enable the recovery of a substance of interest from a fluid. Such fluids may include gases or liquids. Such recovery may involve the adsorption or absorption of the substance of interest (e.g., a biopharmaceutical compound) by the grafted polymer layer.

[0062] The purposes and advantages of this specification are further illustrated by the following examples, which are not limiting; however, the specific materials and their quantities described in these examples, as well as other conditions and details, should not be construed as unduly limiting this specification. [Examples]

[0063] Unless otherwise specified, all parts, percentages, ratios, etc., in the examples and the rest of the specification are by weight, and all reagents used in the examples were obtained from, or are readily available from, common chemical suppliers such as Sigma-Aldrich Company (Saint Louis, Missouri), or may be synthesized by conventional methods. [Table 1]

[0064] Test method

[0065] BET surface area

[0066] BET surface area was measured by gas adsorption experiments performed using an Accelerated Surface Area and Pore Analysis (ASAP) 2020 Plus system instrument from Micromeritics Instrument Corporation (Norcross, GA). 50–250 milligrams of sample were first degassed in a Micromeritics 0.5-inch diameter sample tube by heating at 80°C for 3 hours under high vacuum (500 μmHg) in the degassing port. At the end of this degassing process, the sample tube was refilled with nitrogen and transferred to the analysis port. The sample was then further degassed in the analysis port of the analyzer at 80°C for 3 hours under ultra-high vacuum (3–7 μmHg). The nitrogen adsorption isotherm at 77K was obtained during low-pressure dosing (5cm) with a relative pressure (p / p°) of less than 0.1. 3 The pressures were obtained using a pressure table of linearly spaced pressure points in the range of p / p° from 0.1 to 0.998, with p / p° being 10. For all isotherms, the following equilibrium intervals were used: p / p° = 10 -5 Less than 90 seconds, p / p° is 10 -5 40 seconds in the range of ~0.1, and 20 seconds at p / p° greater than 0.1. Helium was used for free-space measurements and measured at both room temperature and 77K after nitrogen adsorption analysis. BET specific surface area (SA BET The pore size was calculated from nitrogen adsorption data using a multipoint Brunauer-Emmett-Teller (BET) analysis. The apparent pore distribution was calculated from nitrogen adsorption data using a standard 77K nitrogen density function theory (DFT) model and density function theory (DFT) analysis. The total pore volume was calculated from the total amount of adsorbed nitrogen at approximately 0.98 p / p°. BET, DFT, and total pore volume analyses were performed using Micromeritics MicroActive Version 5.02 software.

[0067] Scanning electron microscope (SEM)

[0068] High-magnification images were acquired using a field emission SEM (FE-SEM) (model Hitachi S-4700, obtained from Hitachi High-Tech Corporations (Japan)).

[0069] Nonwoven fabric 1: A nonporous fiber nonwoven fabric prepared according to PE5 of U.S. Provisional Patent Application No. 63 / 422,139 (filed November 3, 2022). This nonwoven fabric is 4.0 m 2 It had a BET surface area of ​​ / g.

[0070] Nonwoven fabric 2: A porous fiber nonwoven fabric formed after cold / hot stretching of nonwoven fabric 1, prepared according to E5 of U.S. Provisional Patent Application No. 63 / 422,139. ​​This nonwoven fabric is 48.2 m 2 It had a BET surface area of ​​ / g.

[0071] Example 1

[0072] Three 4-inch x 6-inch (10cm x 15cm) samples were cut from nonwoven fabric 1 and nonwoven fabric 2 and weighed. The nonwoven fabric samples were placed in a glove box under a nitrogen atmosphere and purged with oxygen for 30 minutes to 2 hours until the oxygen concentration was 20 ppm (parts per million) or less. Inside the glove box, each nonwoven fabric was placed in a separate plastic bag with a sealed top and sealed before being removed from the glove box. Each nonwoven fabric sample was irradiated in a single pass with an electron beam having an electron acceleration voltage of 300 kV (available from Energy Sciences Inc., Wilmington, MA) inside its plastic bag. The irradiation dose was set to 10 Mrad. The irradiated plastic bags were returned to the glove box and purged with oxygen into the glove box containing the samples as described above. Then, each nonwoven fabric sample was removed from the plastic bag and placed in a new plastic bag with a sealed top. [Table 2]

[0073] Monomer solutions 1, 2, and 3 were each prepared in glass bottles using the weight percentages of the materials listed in Table 1. Monomer solutions 1 and 2 appeared opaque as emulsions, while monomer solution 3 was clear. Each monomer solution was purged with nitrogen gas before sealing the bottles. All bottles were moved to the same glove box where the irradiated samples were held in new sealed plastic bags. The monomer solutions were further purged for 1–10 minutes with the caps removed. The specified monomer solution (20–30 monomer solution:1 weight ratio of nonwoven fabric) was then added to each plastic bag containing the irradiated nonwoven fabric sample. The monomer solution was spread within the plastic bag to saturate the nonwoven fabric sample. The plastic bags were sealed, and the samples were allowed to react for 3 hours.

[0074] Each grafted nonwoven fabric sample was removed from its plastic bag and held in boiling water for 1 hour. Next, the grafted nonwoven fabric samples were immersed in deionized water for a further 1 hour, and then dried at room temperature for at least 48 hours. The grafted nonwoven fabric samples were weighed again, and the weight increase rate (i.e., (final weight - initial weight) / initial weight) was calculated. The results are shown in Table 2. [Table 3]

[0075] Figure 2 shows the SEM image of Comparative Example 2, and Figure 3 shows the SEM image of Example 2.

[0076] Foreseeable modifications and changes to the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The present invention should not be limited to the embodiments described herein for illustrative purposes. In the event of any discrepancy or inconsistency between the contents of this specification and any disclosure in any document incorporated herein by reference or reference, the described specification shall prevail.

Claims

1. A nonwoven fabric substrate containing multiple porous polymer fibers, Each porous polymer fiber has an outer main surface and multiple pores. At least a portion of the pores opens to the outer main surface and extends from that outer main surface to the inner portion of the porous polymer fibers, and At least a portion of the aforementioned holes are in fluid communication with a nonwoven fabric substrate, Multiple polymer chains are grafted onto the outer main surface of the porous polymer fiber. Grafted articles, including [the specified material].

2. The grafted article according to claim 1, wherein at least a portion of the polymer chain comprises a functional end group.

3. The grafted article according to claim 2, wherein the functional terminal group is a sample-binding group.

4. The grafted article according to claim 2, wherein the functional terminal group comprises an ionic group, and optionally the ionic group comprises a sulfonic acid, an amino group, a quaternary ammonium group, or a combination thereof.

5. The grafted article according to any one of claims 1 to 4, wherein the plurality of porous polymer fibers have a first average fiber diameter, and the plurality of polymer chains extending from the outer main surface of the porous polymer fibers result in a second average fiber diameter, the second average fiber diameter being at least 10% larger than the first average fiber diameter.

6. The grafted article according to any one of claims 1 to 5, wherein a plurality of polymer chains extending from the outer main surface of the porous polymer fibers cover, on average, at least 50% of the surface of the plurality of porous polymer fibers.

7. The grafted article according to any one of claims 1 to 6, wherein the porous polymer fibers exhibit a porosity of 5% to 80% by volume.

8. The grafted article according to any one of claims 1 to 7, wherein the plurality of holes have an average pore diameter of 5 to 500 nm, assuming they have a circular cross-section.

9. The grafted article according to any one of claims 1 to 8, wherein the porous polymer fiber comprises one or more semicrystalline polymers.

10. The grafted article according to any one of claims 1 to 9, wherein the porous polymer fibers comprise at least one of polypropylene, polyethylene, polymethylpentene, polyoxymethylene, polybutene-1, polyvinylidene fluoride, or copolymers thereof.

11. The grafted article according to any one of claims 1 to 10, wherein the porous polymer fibers include polypropylene.

12. The grafted article according to claim 11, wherein the porous polymer fibers containing the polypropylene have a number average molecular weight of 250,000 g / mol or more and 800,000 g / mol or less.

13. The grafted article according to any one of claims 1 to 12, wherein the porous polymer fibers include microfibers that connect lamellar microstructures.

14. The grafted article according to any one of claims 1 to 13, wherein at least 50% by weight of the nonwoven fabric base material is composed of the porous polymer fibers.

15. The porous polymer fibers are at least 5 m ２ A grafted article according to any one of claims 1 to 14, having an average surface area of ​​ / g.

16. The porous polymer fibers are at least 40 m ２ A grafted article according to any one of claims 1 to 15, having an average surface area of ​​ / g.

17. A method for manufacturing grafted articles, (i) To provide a nonwoven fabric substrate containing a plurality of porous polymer fibers, Each porous polymer fiber has an outer main surface and multiple pores. At least a portion of the pores opens to the outer main surface and extends from that outer main surface to the inner portion of the porous polymer fibers, and To provide a nonwoven fabric substrate in which at least a portion of the aforementioned holes are in fluid communication, (ii) Contacting the nonwoven fabric substrate with a polymerizable solution, (iii) Exposing the nonwoven fabric substrate to a controlled amount of ionizing radiation to form a grafted article. Methods that include...

18. The method according to claim 17, wherein the nonwoven fabric substrate is first exposed to the controlled amount of ionizing radiation and then brought into contact with the polymerizable solution.

19. The method according to claim 17, wherein the nonwoven fabric substrate is first brought into contact with the polymerizable solution and then exposed to the controlled amount of ionizing radiation.

20. The method according to any one of claims 17 to 19, wherein the ionizing radiation irradiation includes irradiation with electron beams, X-rays, or gamma rays.

21. The polymerizable solution comprises an ethylenically unsaturated moiety and a functional group moiety of formula I: 【Chemistry 1】 [In the formula, X is H or CH] ３ And Y includes a functional terminal group. The method according to any one of claims 17 to 19, comprising a monomer containing the above.

22. The polymerizable solution contains the ionic monomer of formula II: 【Chemistry 2】 [In the formula, R １ is H or CH ３ [where Z is a linear or branched alkylene having 1 to 10 carbon atoms] The method according to any one of claims 19 to 21, comprising a salt thereof.

23. The polymerizable solution comprises an ionic monomer of formula (III): 【Transformation 3】 [wherein, R １ is H or CH ３ ; L is -O- or -NH-; Z is a linear or branched alkylene having 1 to 10 carbon atoms; R ５ , R ６ and R ７ are each independently an aryl or alkyl group; M － is a counter anion] The method according to any one of claims 19 to 22, including the method described in any one of claims 19 to 22.

24. The method according to any one of claims 19 to 23, wherein the ionizing radiation irradiation induces radical polymerization of the polymerizable solution.

25. Porous polymer fibers, The porous polymer fiber has an outer main surface and a plurality of pores, At least a portion of the pores opens to the outer main surface and extends from that outer main surface to the inner portion of the porous polymer fibers, and At least a portion of the aforementioned holes are fluid-communicating, porous polymer fibers, Multiple polymer chains grafted onto the outer main surface of the porous polymer fiber and Grafted fibers containing [unclear material].

26. A method for producing grafted fibers, (i) To provide porous polymer fibers, The porous polymer fiber has an outer main surface and a plurality of pores, At least a portion of the pores opens to the outer main surface and extends from that outer main surface to the inner portion of the porous polymer fibers, and To provide porous polymer fibers in which at least a portion of the aforementioned holes are fluid-communicating, (ii) Contacting the porous fibers with a polymerizable solution, (iii) Exposing the porous fibers to a controlled amount of ionizing radiation to form grafted fibers. Methods that include...

Images