Bicomponent fibers comprising ethylene / alpha-olefin interpolymers

Abstract

Bicomponent fibers are provided. The bicomponent fibers include a first region and a second region. The first region includes a first ethylene / alpha-olefin interpolymer, and the second region includes a second ethylene / alpha-olefin interpolymer. The first ethylene / alpha-olefin interpolymer has a maximum peak melting temperature (Tm) less than 130°C and at least 3.5°C higher than the maximum peak melting temperature of the second ethylene / alpha-olefin interpolymer. In embodiments, the bicomponent fibers can be used to form nonwoven fabrics with improved tensile strength, elongation at break, and / or abrasion resistance.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to bicomponent fibers comprising ethylene / alpha-olefin interpolymers and nonwoven fabrics comprising the fibers.

[0002] Introduction Bicomponent fibers are fibers composed of two different regions and corresponding polymer compositions extruded from the same spinneret, with both compositions contained within the same filament or fiber. When the fiber leaves the spinneret, it consists of immiscible components that fuse at the interface. The two polymer compositions may differ in their chemical and / or physical properties. Bicomponent fibers can be formed by spinning techniques known in the art and used to form nonwoven fabrics. Nonwoven fabrics formed from bicomponent fibers can have similar or different properties to nonwoven fabrics formed from monocomponent fibers. However, there are challenges in developing highly spinnable, fine-denier bicomponent fibers and nonwoven fabrics made from such bicomponent fibers that are recyclable and have a combination of excellent softness, tensile strength, abrasion resistance, and / or elongation at break. Summary of the Invention

[0003] Embodiments of the present disclosure provide bicomponent fibers that are strong and highly spinnable in some aspects, as evidenced by high filament speeds and low denier. The bicomponent fibers can be used to form nonwoven fabrics compatible with polyethylene recycle streams and can have a combination of enhanced tensile strength, abrasion resistance, and / or elongation at break. The bicomponent fibers include a first region comprising a first ethylene / alpha-olefin interpolymer and a second region comprising a second ethylene / alpha-olefin interpolymer.

[0004] Disclosed herein is a bicomponent fiber comprising a first region and a second region, wherein the first region comprises a first ethylene / alpha-olefin interpolymer having a maximum peak melting temperature (Tm) less than 130°C, and the second region comprises a second ethylene / alpha-olefin interpolymer having a density less than the density of the first ethylene / alpha-olefin interpolymer composition, wherein the maximum peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer is at least 3.5°C higher than the maximum peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer, and the first region and the second region are arranged in a core-sheath configuration.

[0005] Also disclosed herein are nonwoven fabrics. The nonwoven fabrics are formed from the bicomponent fibers disclosed herein. In embodiments, the nonwoven fabrics have the following properties: a fiber denier of 1.5 g / 9000 m or less, a machine direction tensile strength of greater than 11.0 Newtons per inch for a 20 gram per square meter (gsm) nonwoven fabric, a machine direction elongation at break of greater than 100% for a 20 gsm nonwoven fabric, and a tensile strength of 0.18 mg / cm for a 20 gsm nonwoven fabric. 2 In embodiments, nonwoven fabrics formed from the bicomponent fibers disclosed herein have one or more of the following characteristics: a machine direction abrasion resistance of less than 40.0°C to 68.0°C (WT %) in an elution profile via an improved comonomer composition distribution (ICCD) procedure; 40~68℃ ), the elution profile via ICCD comprises a combination of at least 12 weight percent (wt %) of the first ethylene / alpha-olefin interpolymer and the second ethylene / alpha-olefin interpolymer in a temperature range of 40.0°C to 68.0°C, wherein the weight percent can be determined by the test method described below.

[0006] Additional features and advantages of the embodiments will be set forth in the detailed description that follows, and will in part be readily apparent to those skilled in the art from that description, or will be learned by practicing the embodiments described herein, including the detailed description that follows, the claims, and the accompanying drawings.

[0007] It is to be understood that both the foregoing and the following descriptions are intended to describe various embodiments and provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying figures are included to provide a further understanding of the various embodiments, and are incorporated in and constitute a part of this specification. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a single reactor data flow diagram. [Figure 2] FIG. 1 is a schematic diagram of a dual reactor data flow diagram. [Figure 3] 1 is an ICCD elution profile of the nonwoven fabric of Example 2 of the present invention showing WT (T) versus temperature over the temperature range of 40.0° C. to 68.0° C. (WT 40-68° C.). DETAILED DESCRIPTION OF THE INVENTION

[0009] Aspects of the disclosed bicomponent fibers are described in more detail below. The bicomponent fibers can be used to form nonwoven fabrics, which can have a wide variety of uses, including, for example, wipes, face masks, tissues, bandages, medical gowns, infant diapers, adult incontinence, and other medical and hygiene products. It should be noted, however, that this is merely an exemplary implementation of the embodiments disclosed herein. The embodiments are also applicable to other technologies prone to problems similar to those described above.

[0010] As used herein, the terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional component, step, or procedure, whether specifically disclosed or not. For the avoidance of doubt, all compositions claimed through the use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any subsequent description any other component, step, or procedure, except those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineated or listed.

[0011] As used herein, the term "interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. Thus, the term interpolymer includes copolymers (used to refer to polymers prepared from two different types of monomers) and polymers prepared from three or more different types of monomers.

[0012] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the term polymer encompasses the term homopolymer (used to refer to a polymer prepared from only one type of monomer, with the understanding that minor amounts of impurities may be incorporated into the polymer structure), and the term interpolymer, as defined above. The polymer may be a single polymer or a polymer blend.

[0013] As used herein, the terms "nonwoven," "nonwoven web," and "nonwoven fabric" are used interchangeably herein. "Nonwoven" refers to a web or fabric having a structure of individual fibers or threads interleaved randomly, rather than in a discernible manner as in knitted fabrics.

[0014] As used herein, the term "spunbond" refers to the production of nonwoven fabrics that includes the steps of: (a) extruding molten thermoplastic strands from a plurality of minute capillaries called spinnerets; (b) quenching the strands with a generally cooled stream of air to hasten their solidification; (c) drawing the strands by advancing them through a quench zone under a drawing tension, which can be applied by entraining the strands with an air stream or by winding them around mechanical drawing rolls of the type commonly used in the textile industry; (d) collecting the drawn strands into a web on a foraminous surface (e.g., a moving screen or perforated belt); and (e) bonding the web of loose strands into a nonwoven fabric. Bonding can be achieved by a variety of means, including, but not limited to, thermal calendering, adhesive bonding, hot air bonding, needlepunching, hydroentangling, and combinations thereof.

[0015] As used herein, the term "meltblown" generally refers to the production of nonwoven fabrics via a process that includes the following steps: (a) extruding molten thermoplastic strands through a spinneret, (b) simultaneously quenching and drawing the polymer stream immediately below the spinneret using a high-velocity, heated air stream, and (c) collecting the drawn strands into a web on a collecting surface. Meltblown webs can be bonded by a variety of means, including, but not limited to, autogenous bonding (i.e., self-bonding without further processing), thermal calendering processes, adhesive bonding processes, hot air bonding processes, needlepunching processes, hydroentangling processes, and combinations thereof.

[0016] A bicomponent fiber may comprise a combination of two or more preferred embodiments as disclosed herein.

[0017] Nonwoven fabrics formed from bicomponent fibers may comprise a combination of two or more preferred embodiments as disclosed herein.

[0018] fiber Bicomponent fibers according to embodiments of the present disclosure can be formed into fibers through different techniques, for example, via melt spinning. In melt spinning, a first region and a second region are melted, coextruded, and forced through fine orifices in a metallic plate, spinneret, into air or other gas, where the coextruded region can be cooled and solidified to form a bicomponent fiber. The solidified filaments can be drawn through an air jet, rotating roll, or godet and laid on a conveyor belt as a web to form a nonwoven fabric. Bicomponent fibers according to embodiments of the present disclosure contain two regions (i.e., a first region and a second region). The regions can be configured in a core-sheath configuration, i.e., referred to herein as a concentric core-sheath or islands-in-the-sea configuration. For example, in embodiments, the first region and the second region are arranged in a concentric core-sheath configuration, where the first region is the core region and the second region is the sheath region, and the sheath region surrounds the core region. In other embodiments, the first region and second region are arranged in a core-sheath, sea-island configuration, where the first region is a plurality of core regions (also called islands) and the second region is a sheath region (also called sea), and the sheath region or sea surrounds the plurality of core regions or islands.

[0019] In embodiments, the bicomponent fiber includes a first region and a second region, and the weight ratio of the first region to the second region is from 10:90 to 90:10. All individual values ​​and subranges between the ratios of 90:10 to 10:90 are disclosed and included herein. For example, in embodiments, the weight ratio of the first region to the second region can be from 80:20 to 20:80, from 70:30 to 30:70, from 60:40 to 40:60, or from 55:45 to 45:55.

[0020] In embodiments, the bicomponent fiber has a denier of less than 50 g / 9000 m. All individual values ​​and subranges less than 50 g / 9000 m are disclosed and included herein. For example, the bicomponent fiber can have a denier of less than 40, less than 30, less than 20, less than 10, less than 5, less than 3, less than 2, less than 1.5, or less than 1.2 g / 9000 m, or can have a denier in the ranges of 0.1 to 50, 0.1 to 40, 0.1 to 30, 0.1 to 20, 0.1 to 10, 0.1 to 5, 0.1 to 2.0, 0.1 to 1.5, 0.1 to 1.2, 1 to 50, 1 to 40, 1 to 30, 1 to 20, 1 to 10, 1 to 5, 1 to 2.0, 1 to 1.5, or 1 to 1.2 g / 9000 m, where denier can be measured by the test methods described below.

[0021] First Area The first region of the bicomponent fiber comprises a first ethylene / alpha-olefin interpolymer.

[0022] In embodiments, the first region of the bicomponent fiber comprises the first ethylene / alpha-olefin interpolymer in an amount of at least 50 weight percent (wt%), based on the total weight of the first region. All individual values ​​and subranges of at least 50 wt% are disclosed and included herein. For example, in embodiments, the first region can comprise the first ethylene / alpha-olefin interpolymer in an amount of at least 50 wt%, at least 60 wt%, at least 75 wt%, at least 85 wt%, at least 90 wt%, at least 95 wt%, or at least 99 wt%, based on the total weight of the first region. In other embodiments, the first region can comprise the first ethylene / alpha-olefin interpolymer in an amount of 50 to 100 weight%, 60 to 100 weight%, 75 to 100 weight%, 85 to 100 weight%, 90 to 100 weight%, 95 to 100 weight%, 99 to 100 weight%, 50 to 95 weight%, 60 to 95 weight%, 75 to 95 weight%, 85 to 95 weight%, or 90 to 95 weight%, based on the total weight of the first region.

[0023] The term "ethylene / alpha-olefin interpolymer" refers to a polymer comprising ethylene and an alpha-olefin having 3 or more carbon atoms. In an embodiment, the first ethylene / alpha-olefin interpolymer comprises greater than 55 wt.% of units derived from ethylene and less than 45 wt.% of units derived from one or more alpha-olefin comonomers (based on the total amount of polymerizable monomers). All individual values ​​and subranges of greater than 55 wt.% of units derived from ethylene and less than 45 wt.% of units derived from one or more alpha-olefin comonomers are included and disclosed herein. For example, in embodiments, the first ethylene / alpha-olefin interpolymer is (a) more than 55 wt%, more than 70 wt%, more than 85 wt%, more than 90 wt%, more than 92 wt%, more than 95 wt%, more than 97 wt%, more than 98 wt%, more than 99 wt%, or 99.5 wt%, or from 55 wt% to 99.5 wt%, from 55 wt% to 95 wt%, from 55 wt% to 90 wt%, from 55 wt% to 99.5 wt%, from 55 wt% to 99 wt%, from 55 wt% to 99 wt%, from 55 wt% to 99 wt%, from 55 wt% to 97 wt%, from 55 wt% to 94 wt%, from 75 wt% to 90 wt%, from 90 wt% to 99.9 wt%, from 90 wt% to 99.5 wt%, from 90 wt% to 97 wt%, or 90% to 95% by weight of units derived from ethylene, and (b) less than 45%, less than 30%, less than 20%, less than 18%, less than 15%, less than 12%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or 0.1 to 45%, 0.1 to 25%, 0.1 to 10%, 0.1 to 5%, 0.5 to 20%, 0.5 to 10%, 0.5 to 5%, 1 to 20%, 1 to 10%, 1 to 5%, 5 to 20%, or 5 to 10% by weight of units derived from one or more α-olefin comonomers. Comonomer content can be determined using any suitable technique, such as techniques based on nuclear magnetic resonance ("NMR") spectroscopy, for example, as described in U.S. Patent No. 7,498,282, incorporated herein by reference. 13 It can be measured by C NMR analysis.

[0024] Suitable alpha-olefin comonomers typically have 20 or fewer carbon atoms. The one or more alpha-olefins of the first ethylene / alpha-olefin interpolymer may be selected from the group consisting of C3 to C20 acetylenically unsaturated monomers and C4 to C18 diolefins. For example, the alpha-olefin comonomers may have 3 to 10 carbon atoms or 3 to 8 carbon atoms. Exemplary alpha-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more alpha-olefin comonomers of the first ethylene / alpha-olefin interpolymer can be, for example, selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene, or alternatively, from the group consisting of 1-butene, 1-hexene, and 1-octene, or alternatively, from the group consisting of 1-hexene and 1-octene. In one or more embodiments, the first ethylene / alpha-olefin interpolymer can comprise from greater than 0 wt% to less than 45 wt% of units derived from one or more of 1-octene, 1-hexene, or 1-butene comonomers.

[0025] In an embodiment, the first ethylene / alpha-olefin interpolymer has a viscosity of 0.940 to 0.965 g / cm 3 It has a density in the range of 0.940 to 0.965 g / cm 3 All individual values ​​and subranges of density within the range are disclosed and included herein. For example, the first ethylene / alpha-olefin interpolymer may have a density of 0.940 to 0.965 g / cm. 3 , 0.940~0.960g / cm 3 , 0.945~0.965g / cm 3 , 0.945~0.960g / cm 3 , 0.950~0.965g / cm 3 , or 0.950 to 0.960 g / cm 3 The density can be measured by ASTM D792.

[0026] In an embodiment, the first ethylene / alpha-olefin interpolymer has a melt index (I2), as measured by ASTM D1238, 190°C, 2.16 kg, in the range of 10 to 60 g / 10 min. All individual values ​​and subranges from 10 to 60 g / 10 min are included herein and disclosed. For example, in some embodiments, the first ethylene / alpha-olefin interpolymer can have a melt index (I2) in the range of 10 to 60 g / 10 min, 10 to 50 g / 10 min, 10 to 40 g / 10 min, 10 to 30 g / 10 min, 10 to 20 g / 10 min, 20 to 60 g / 10 min, 20 to 50 g / 10 min, 20 to 40 g / 10 min, 20 to 30 g / 10 min, 15 to 60 g / 10 min, 15 to 50 g / 10 min, 15 to 40 g / 10 min, 15 to 30 g / 10 min, or 15 to 20 g / 10 min, wherein the melt index (I2) can be measured by ASTM D1238, 190° C., 2.16 kg.

[0027] In an embodiment, the first ethylene / alpha-olefin interpolymer has a ratio of weight average molecular weight to number average molecular weight (M), as determined by conventional gel permeation chromatography (GPC), of 1.5 to 5.0. w(GPC) / M n(GPC) ) of 1.5 to 5.0. w(GPC) / M n(GPC) All individual values ​​and subranges of the molecular weight distribution (M) are disclosed and included herein. For example, the first ethylene / alpha-olefin interpolymer may have a molecular weight distribution (M) of 1.5 to 5.0, 1.5 to 4.0, 1.5 to 3.0, 1.5 to 2.5, 2.0 to 5.0, 2.0 to 4.0, 2.0 to 3.0, or 2.0 to 2.5. w(GPC) / M n(GPC) ), and the molecular weight distribution (M w(GPC) / M n(GPC) ) can be measured by the conventional GPC test method described below.

[0028] In embodiments, the first region can also include additional components, such as one or more other polymers and / or one or more additives. The other polymer can include another ethylene / alpha-olefin interpolymer, a post-consumer or post-industrial recycled polymer, a polyester, a propylene-based polymer (e.g., a polypropylene homopolymer, a propylene-ethylene copolymer, or a propylene / alpha-olefin interpolymer), or a propylene-based plastomer or elastomer. The amount of the other polymer can be up to 50 wt. % based on the total weight of the first region. For example, in one embodiment, the first region can include up to 50 wt. % of a propylene-based plastomer or propylene-based elastomer (such as VERSIFY™ polymers available from Dow Chemical Company and VISTAMAXX™ polymers available from ExxonMobil Chemical Co.), a low modulus and / or low molecular weight polypropylene (such as L-MODU™ polymers from Idemitsu), a random copolypropylene, or a propylene-based olefin block copolymer (INTUNE™). Possible additives may include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antimicrobial agents, odor reducers, antifungal agents, and combinations thereof. The first region can comprise from about 0.01, or 0.1, or 1 to about 25, or about 20, or about 15, or about 10, or about 5 weight percent total weight of additives, based on the total weight of the first region.

[0029] In an embodiment, the first ethylene / alpha-olefin interpolymer has a maximum peak melting temperature (Tm) of less than 130° C., as measured by the Differential Scanning Calorimetry (DSC) test method described below. All individual values ​​and subranges less than 130° C. are disclosed and incorporated herein. For example, in embodiments, the highest peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer, as measured by the DSC test method described below, can be less than 130°C, less than 129.5°C, less than 129°C, or less than 128.5°C, or can be in the range of 120°C to 130°C, 125°C to 130°C, 127°C to 130°C, 128°C to 130°C, 125°C to 129.5°C, 126°C to 129°C, 126°C to 128°C, 127°C to 129°C, 127°C to 128.5°C, or 127°C to 128°C.

[0030] In an embodiment, the first ethylene / alpha-olefin interpolymer has a maximum peak crystallization temperature (Tc) in the range of 108°C to 118°C, where the maximum peak crystallization temperature (Tc) can be measured by the DSC test method described below. All individual values ​​and subranges from 108°C to 118°C are disclosed and included herein. For example, the first ethylene / alpha-olefin interpolymer can have a maximum peak crystallization temperature (Tc) in the range of 108°C to 118°C, 110°C to 118°C, 112°C to 118°C, 108°C to 116°C, 108°C to 115°C, 110°C to 116°C, 110°C to 115°C, 112°C to 116°C, or 113°C to 115°C, as measured by the DSC test method described below.

[0031] Second Area The second region of the bicomponent fiber comprises a second ethylene / alpha-olefin interpolymer.

[0032] In embodiments, the second region of the bicomponent fiber comprises the second ethylene / alpha-olefin interpolymer in an amount of at least 50 weight percent (wt%), based on the total weight of the second region. All individual values ​​and subranges of at least 50 wt% are disclosed and included herein. For example, in embodiments, the second region can comprise the second ethylene / alpha-olefin interpolymer in an amount of at least 50 wt%, at least 60 wt%, at least 75 wt%, at least 85 wt%, at least 90 wt%, at least 95 wt%, or at least 99 wt%, based on the total weight of the second region. In other embodiments, the second region can comprise the second ethylene / alpha-olefin interpolymer in an amount of 50 to 100 weight%, 60 to 100 weight%, 75 to 100 weight%, 85 to 100 weight%, 90 to 100 weight%, 95 to 100 weight%, 99 to 100 weight%, 50 to 95 weight%, 60 to 95 weight%, 75 to 95 weight%, 85 to 95 weight%, or 90 to 95 weight%, based on the total weight of the second region.

[0033] In an embodiment, the second ethylene / alpha-olefin interpolymer comprises greater than 55 wt.% of units derived from ethylene and less than 45 wt.% of units derived from one or more alpha-olefin comonomers (based on the total amount of polymerizable monomers). All individual values ​​and subranges of greater than 55 wt.% of units derived from ethylene and less than 45 wt.% of units derived from one or more alpha-olefin comonomers are included and disclosed herein. For example, the second ethylene / alpha-olefin interpolymer may be (a) more than 55 wt%, more than 70 wt%, more than 85 wt%, more than 90 wt%, more than 92 wt%, more than 95 wt%, more than 97 wt%, more than 98 wt%, more than 99 wt%, 99.5 wt%, or from 55 wt% to 99.5 wt%, from 55 wt% to 95 wt%, from 55 wt% to 90 wt%, from 55 wt% to 99.5 wt%, from 55 wt% to 9 ...7 wt%, from 55 wt% to 94 wt%, from 75 wt% to 90 wt%, from 90 wt% to 99.9 wt%, from 90 wt% to 99.5 wt%, from 90 wt% to 97 wt%, or from 9 and (b) less than 45%, 30%, 20%, 18%, 15%, 12%, 10%, 8%, 5%, 4%, 3%, 2%, 1%, or 0.1-45%, 0.1-25%, 0.1-10%, 0.1-5%, 0.5-20%, 0.5-10%, 0.5-5%, 1-20%, 1-10%, 1-5%, 5-20%, or 5-10% by weight of units derived from one or more α-olefin comonomers. Comonomer content can be determined using any suitable technique, such as techniques based on nuclear magnetic resonance ("NMR") spectroscopy, for example, as described in U.S. Patent No. 7,498,282, incorporated herein by reference. 13 It can be measured by C NMR analysis.

[0034] Suitable alpha-olefin comonomers typically have 20 or fewer carbon atoms. The one or more alpha-olefins of the second ethylene / alpha-olefin interpolymer may be selected from the group consisting of C3 to C20 acetylenically unsaturated monomers and C4 to C18 diolefins. For example, the alpha-olefin comonomers may have 3 to 10 carbon atoms or 3 to 8 carbon atoms. Exemplary alpha-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more alpha-olefin comonomers of the second ethylene / alpha-olefin interpolymer can be, for example, selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene, or alternatively, from the group consisting of 1-butene, 1-hexene, and 1-octene, or alternatively, from the group consisting of 1-hexene and 1-octene. In one or more embodiments, the second ethylene / alpha-olefin interpolymer can comprise from greater than 0 wt% to less than 45 wt% of units derived from one or more of 1-octene, 1-hexene, or 1-butene comonomers.

[0035] In an embodiment, the second ethylene / alpha-olefin interpolymer has a density that is less than the density of the first ethylene / alpha-olefin interpolymer. In an embodiment, the density of the first ethylene / alpha-olefin interpolymer is at least 0.022 g / cm greater than the density of the second ethylene / alpha-olefin interpolymer. 3 High. At least 0.022g / cm 3 All individual values ​​and subranges are included and disclosed herein. For example, the density of the first ethylene / alpha-olefin interpolymer may be at least 0.022 g / cm greater than the density of the second ethylene / alpha-olefin interpolymer. 3 , 0.025g / cm 3 , 0.027g / cm 3 , 0.029g / cm 3, 0.031g / cm 3 , 0.033g / cm 3 , 0.035g / cm 3 , 0.037g / cm 3 , 0.039g / cm 3 , or 0.041 g / cm 3 The density can be increased, and the density can be measured by ASTM D792. In other embodiments, the difference between the density of the first ethylene / alpha-olefin interpolymer and the density of the second ethylene / alpha-olefin interpolymer can be from 0.023 to 0.085 g / cm 3 , 0.023~0.050g / cm 3 , 0.023~0.040g / cm 3 , 0.029~0.085g / cm 3 , 0.029~0.050g / cm 3 , 0.031~0.085g / cm 3 , 0.031~0.050g / cm 3 , 0.031~0.040g / cm 3 , 0.039~0.050g / cm 3 , or 0.039 to 0.085 g / cm 3 and the density can be measured by ASTM D792.

[0036] In an embodiment, the second ethylene / alpha-olefin interpolymer has a viscosity of 0.880 to 0.940 g / cm 3 It has a density in the range of 0.880 to 0.940 g / cm 3 All individual values ​​and subranges of density in the range of 0.880 to 0.940 g / cm are disclosed and included herein. For example, in some embodiments, the second ethylene / alpha-olefin interpolymer has a density of 0.880 to 0.940 g / cm. 3 , 0.880~0.930g / cm 3 , 0.880~0.920g / cm 3 , 0.890~0.940g / cm 3 , 0.890~0.930g / cm 3 , 0.890~0.920g / cm 3 , 0.890~0.910g / cm 3, 0.900~0.940g / cm 3 , 0.900~0.930g / cm 3 , 0.900~0.920g / cm 3 , or 0.900 to 0.910 g / cm 3 The density can be measured by ASTM D792.

[0037] In an embodiment, the second ethylene / alpha-olefin interpolymer has a melt index (I2), as measured by ASTM D1238, 190°C, 2.16 kg, in the range of 10 to 60 g / 10 min. All individual values ​​and subranges from 10 to 60 g / 10 min are included herein and disclosed. For example, in some embodiments, the second ethylene / alpha-olefin interpolymer can have a melt index (I2) in the range of 10 to 60 g / 10 min, 10 to 50 g / 10 min, 10 to 40 g / 10 min, 10 to 30 g / 10 min, 10 to 20 g / 10 min, 20 to 60 g / 10 min, 20 to 50 g / 10 min, 20 to 40 g / 10 min, 20 to 30 g / 10 min, 15 to 60 g / 10 min, 15 to 50 g / 10 min, 15 to 40 g / 10 min, 15 to 30 g / 10 min, or 15 to 20 g / 10 min, wherein the melt index (I2) can be measured by ASTM D1238, 190°C, 2.16 kg.

[0038] In an embodiment, the second ethylene / alpha-olefin interpolymer has a ratio of weight average molecular weight to number average molecular weight (M w(GPC) / M n(GPC) ) of 1.5 to 5.0. w(GPC) / M n(GPC) All individual values ​​and subranges of the molecular weight distribution (M) are disclosed and included herein. For example, the second ethylene / alpha-olefin interpolymer may have a molecular weight distribution (M) of 1.5 to 5.0, 1.5 to 4.0, 1.5 to 3.0, 1.5 to 2.5, 2.0 to 5.0, 2.0 to 4.0, 2.0 to 3.0, or 2.0 to 2.5. w(GPC) / M n(GPC) ), and the molecular weight distribution (Mw(GPC) / M n(GPC) ) can be measured by the conventional gel permeation chromatography (GPC) test method described below.

[0039] In embodiments, the second region can also include additional components, such as one or more other polymers and / or one or more additives. The other polymer can include another ethylene / alpha-olefin interpolymer, a polyester, a post-consumer or post-industrial recycled polymer, a propylene-based polymer (e.g., a polypropylene homopolymer, a propylene-ethylene copolymer, or a propylene / alpha-olefin interpolymer), or a propylene-based plastomer or elastomer. The amount of the other polymer can be up to 50 wt. % based on the total weight of the second region. For example, in embodiments, the second region can include up to 50 wt. % of a propylene-based plastomer or propylene-based elastomer (such as VERSIFY™ polymers available from Dow Chemical Company and VISTAMAXX™ polymers available from ExxonMobil Chemical Co.), a low modulus and / or low molecular weight polypropylene (such as L-MODU™ polymers from Idemitsu), a random copolypropylene, or a propylene-based olefin block copolymer (INTUNE™). Possible additives may include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antimicrobial agents, odor reducers, antifungal agents, and combinations thereof. The second region can contain from about 0.01 or 0.1 or 1 to about 25 or about 20 or about 15 or about 10 or about 5 weight percent additives, based on the total weight of the second region.

[0040] In an embodiment, the first ethylene / alpha-olefin interpolymer has a maximum peak melting temperature (Tm) of less than 130°C, and the maximum peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer is at least 3.5°C higher than the maximum peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer, where the maximum peak melting temperature (Tm) can be measured by the DSC test method described below. All individual values ​​and subranges of at least 3.5°C are disclosed and included herein. For example, in some embodiments, the maximum peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer is at least 3.5°C, at least 4.0°C, at least 4.5°C, or at least 5°C higher than the maximum peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer. In other embodiments, the difference between the highest peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer and the highest peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer is in the range of 3.5°C to 60°C, 4.0°C to 60°C, 4.5°C to 60°C, 5°C to 60°C, 3.5°C to 45°C, 4.0°C to 45°C, 5°C to 45°C, 3.5°C to 30°C, 4.0°C to 30°C, 4.5°C to 30°C, 5°C to 30°C, 3.5°C to 15°C, 4.0°C to 15°C, 4.5°C to 15°C, or 5°C to 15°C, wherein the highest peak melting temperature (Tm) can be measured by the DSC test method described below.

[0041] In an embodiment, the second ethylene / alpha-olefin interpolymer has a maximum peak melting temperature (Tm) of less than 127.5°C as measured by the DSC test method described below. All individual values ​​and subranges less than 127.5°C are disclosed and incorporated herein. For example, in an embodiment, the maximum peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer can be less than 127°C, less than 126.5°C, less than 126°C, less than 125.5°C, less than 125°C, less than 124.5°C, less than 124°C, less than 123.5°C, or less than 123°C, or between 90°C and 127.5°C, between 100°C and 127.5°C, between 110°C and 127.5°C, The maximum peak melting temperature (Tm) may be 120°C to 127.5°C, 122°C to 127.5°C, 90°C to 126°C, 100°C to 126°C, 110°C to 126°C, 120°C to 126°C, 122°C to 126°C, 90°C to 124°C, 100°C to 124°C, 110°C to 124°C, 120°C to 124°C, or 122°C to 124°C, and the maximum peak melting temperature (Tm) can be measured by the DSC test method described below.

[0042] In an embodiment, the second ethylene / alpha-olefin interpolymer has a maximum peak crystallization temperature (Tc) in the range of 90°C to 114.5°C, where the maximum peak crystallization temperature (Tc) can be measured by the DSC test method described below. All individual values ​​and subranges from 90°C to 114.5°C are disclosed and included herein. For example, the second ethylene / alpha-olefin interpolymer can have a maximum peak crystallization temperature (Tc) in the range of 90°C to 114.5°C, 90°C to 110°C, 90°C to 105°C, 95°C to 100°C, 95°C to 110°C, 95°C to 105°C, or 95°C to 100°C, 90°C to 114°C, 90°C to 113°C, or 90°C to 112°C, where the maximum peak crystallization temperature (Tc) can be measured by the DSC test method described below.

[0043] In an embodiment, the first ethylene / alpha-olefin interpolymer has a maximum peak crystallization temperature (Tc) that is at least 3.5°C higher than the maximum peak crystallization temperature (Tc) of the second ethylene / alpha-olefin interpolymer. All individual values ​​and subranges at least 3.5°C higher are included and disclosed herein. For example, the first ethylene / alpha-olefin interpolymer can have a maximum peak crystallization temperature (Tc) that is at least 3.5°C, at least 5°C, at least 7.5°C, at least 10°C, at least 11°C, at least 15°C, or at least 17°C higher than the maximum peak crystallization temperature (Tc) of the second ethylene / alpha-olefin interpolymer, where the maximum peak crystallization temperature (Tc) can be measured by the DSC test method described below. In other embodiments, the difference between the highest peak crystallization temperature (Tc) of the first ethylene / alpha-olefin interpolymer and the highest peak crystallization temperature (Tc) of the second ethylene / alpha-olefin interpolymer is in the range of 3.5°C to 25°C, 5°C to 25°C, 10°C to 25°C, 15°C to 25°C, 3.5°C to 20°C, 5°C to 20°C, 10°C to 20°C, 15°C to 20°C, 3.5°C to 15°C, 5°C to 15°C, or 10°C to 15°C, wherein the highest peak crystallization temperature (Tc) can be measured by the DSC test method described below.

[0044] Synthesis of the First or Second Ethylene / Alpha-Olefin Interpolymer Any conventional polymerization process can be used to produce the first or second ethylene / alpha-olefin interpolymer. Such conventional polymerization processes include, but are not limited to, solution polymerization processes using one or more conventional reactors, such as loop reactors, isothermal reactors, stirred tank reactors, parallel or serial batch reactors, and / or any combination thereof. Such conventional polymerization processes can also include gas phase, solution, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0045] In an embodiment, the solution phase polymerization process occurs in one or more well-stirred reactors, such as one or more loop reactors, at a temperature ranging from 115 to 250°C, e.g., 155 to 225°C, and a pressure ranging from 300 to 1000 psi, e.g., 400 to 750 psi. In one dual reactor embodiment, the temperature in the first reactor is 115 to 190°C, e.g., 115 to 170°C, and the temperature in the second reactor is 150 to 210°C, e.g., 170 to 205°C. In another single reactor embodiment, the temperature in the reactor is 115 to 250°C, e.g., 155 to 225°C. The residence time in a solution phase polymerization process is typically in the range of 2 to 30 minutes, e.g., 5 to 20 minutes. Ethylene, solvent, one or more catalyst systems, optionally one or more cocatalysts, optionally one or more impurity removers, and optionally one or more comonomers are continuously fed into one or more reactors. Exemplary solvents include, but are not limited to, isoparaffin. For example, such a solvent is commercially available from ExxonMobil Chemical Co. (Houston, Texas) under the name ISOPAR E. The resulting mixture of the first or second polyethylene composition and solvent is then removed from the reactor, and the first or second polyethylene composition is isolated. The solvent is typically recovered via a solvent recovery unit, i.e., a heat exchanger and a gas-liquid separator drum, and then recycled to the polymerization system.

[0046] In one embodiment, the first or second ethylene / alpha-olefin interpolymer can be produced via a solution polymerization process in a dual reactor system, e.g., a dual loop reactor system, where ethylene and, optionally, one or more α-olefins are polymerized in the presence of one or more catalyst systems. Additionally, one or more cocatalysts can be present. In another embodiment, the first or second ethylene / alpha-olefin interpolymer can be produced via a solution polymerization process in a single reactor system, e.g., a single loop reactor system, where ethylene and, optionally, one or more α-olefins are polymerized in the presence of one or more catalyst systems.

[0047] One example of a suitable catalyst system for producing the first ethylene / alpha olefin interpolymer can be a catalyst system that includes a procatalyst component that includes a metal-ligand complex of formula (I).

[0048] [ka]

[0049] In formula (I), M is a metal selected from titanium, zirconium, or hafnium, the metal being in a +2, +3, or +4 formal oxidation state; n is 0, 1, or 2; when n is 1, X is a monodentate or bidentate ligand; when n is 2, each X is a monodentate ligand and is the same or different; the metal-ligand complex is overall charge neutral; and each Z is independently —O—, —S—, —N(R N )-, or -P(R P )-, and each R N and R P is (C1-C30) hydrocarbyl or (C1-C30) heterohydrocarbyl, and L is (C1-C 40 ) hydrocarbylene or (C1-C 40 ) heterohydrocarbylene, (C1-C 40 ) Hydrocarbylene has a moiety that includes a linker skeleton of 1 carbon atom to 10 carbon atoms that connects the two Z groups in formula (I) (to which L is attached), or (C1-C 40 ) Heterohydrocarbylene has a moiety containing a linker skeleton of 1 atom to 10 atoms connecting the two Z groups in formula (I), and (C1-C 40 Each of the 1 to 10 atoms of the 1 to 10 atom linker backbone of the heterohydrocarbylene is independently a carbon atom or a heteroatom, and each heteroatom is independently O, S, S(O), S(O), Si(R C )2, Ge(R C )2, P(R C ), or N(R C ) and each R C are independently (C1~C30 ) hydrocarbyl or (C1-C 30 ) heterohydrocarbyl, and R 1 and R 8 are independently -H, (C1~C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R N )2NC(O)-, halogen, and a radical having formula (II), formula (III), or formula (IV).

[0050] [ka]

[0051] In formulas (II), (III), and (IV), R 31~35 , R 41~48 , or R 51~59 Each of (C1 to C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -N=CHR C , -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, RC OC(O)-, R C C(O)N(R N )-, (R N )2NC(O)—, halogen, or —H, with the proviso that R 1 or R 8 is a radical having formula (II), formula (III), or formula (IV), wherein R C、 R N , and R P is as defined above.

[0052] In formula (I), R 2~4 , R 5~7 , or R 9~16 Each of (C1 to C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -N=CHR C , -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R C )2NC(O)—, halogen, or —H, wherein R C、 R N , and R P is as defined above.

[0053] A catalyst system comprising a metal-ligand complex of formula (I) can be catalytically activated by any technique known in the art for activating metal-based catalysts for olefin polymerization reactions. For example, a metal-ligand complex of formula (I) may be made catalytically active by contacting the complex with or combining the complex with an activating cocatalyst. Activating cocatalysts suitable for use herein include alkylaluminums, polymeric or oligomeric alumoxanes (also known as aluminoxanes); neutral Lewis acids, and non-polymeric, non-coordinating, ion-forming compounds (including the use of such compounds under oxidizing conditions). A suitable activation technique is bulk electrolysis. Combinations of one or more of the foregoing activating cocatalysts and techniques are also contemplated. The term "alkylaluminum" refers to monoalkylaluminum dihydrides or dihalides, dialkylaluminum hydrides or halides, or trialkylaluminums. Examples of polymeric or oligomeric alumoxanes include methylalumoxane, triisobutylaluminum-modified methylalumoxane, and isobutylalumoxane.

[0054] The Lewis acid activator (cocatalyst) may be, as described herein, a compound having one to three (C1-C 20 Examples of Group 13 metal compounds include tri((C1-C) hydrocarbyl substituents. 20 )hydrocarbyl)-substituted aluminum, or tri((C1-C 20 )hydrocarbyl)-boron compounds, tri(hydrocarbyl)-substituted aluminum, tri((C1-C 20 )hydrocarbyl)-boron compounds, tri((C1-C 10 ) alkyl) aluminum, tri((C6-C 18 )aryl)boron compounds and their halogenated (including perhalogenated) derivatives. In a further embodiment, the Group 13 metal compound is tris(fluoro-substituted phenyl)borane, tris(pentafluorophenyl)borane. The activating cocatalyst is tris((C1-C 20)hydrocarbyl)borate (e.g., trityl tetrafluoroborate) or tri((C 20 )hydrocarbyl)ammonium tetra((C1-C 20 As used herein, the term "ammonium" refers to a ((C1-C2) ammonium tetrakis(pentafluorophenyl)borane, such as bis(octadecyl)methylammonium tetrakis(pentafluorophenyl)borane. 20 ) Hydrocarbyl) 4N + , ((C1~C 20 )hydrocarbyl)3N(H) + , ((C1~C 20 )hydrocarbyl)2N(H)2 + , (C1~C 20 ) Hydrocarbyl N(H)3 + , or N(H)4 + Each of the nitrogen cations (C1 to C 20 When two or more hydrocarbyls are present, they may be the same or different.

[0055] As a combination of neutral Lewis acid activators (co-catalysts), tri((C1-C4) alkyl)aluminum and halogenated tri((C6-C 18 (aryl)boron compounds, particularly tris(pentafluorophenyl)borane, or a mixture of such neutral Lewis acids with a polymeric or oligomeric alumoxane, or a single neutral Lewis acid, particularly tris(pentafluorophenyl)borane, with a polymeric or oligomeric alumoxane. The molar ratio of (metal-ligand complex):(tris(pentafluorophenyl)borane):(alumoxane) [e.g., Group 4 metal-ligand complex):(tris(pentafluorophenyl)borane):(alumoxane)] is 1:1:1 to 1:10:30, or 1:1:1.5 to 1:5:10.

[0056] Catalyst systems comprising the metal-ligand complexes of formula (I) may be activated to form active catalyst compositions by combination with one or more cocatalysts, such as cation-forming cocatalysts, strong Lewis acids, or combinations thereof. Suitable activating cocatalysts include polymeric or oligomeric aluminoxanes, particularly methylaluminoxane, as well as inert, compatible, non-coordinating, ion-forming compounds. Examples of suitable cocatalysts include modified methyl aluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate (1 - ) amines, and combinations thereof.

[0057] One or more of the aforementioned activating cocatalysts may be used in combination with one another. One preferred combination is a mixture of tri((C1-C4)hydrocarbyl)aluminum, tri((C1-C4)hydrocarbyl)borane, or ammonium borate with an oligomeric or polymeric alumoxane compound. The ratio of the total number of moles of the one or more metal-ligand complexes of formula (I) to the total number of moles of the one or more activating cocatalysts is 1:10,000 to 100:1. This ratio may be at least 1:5000, or at least 1:1000, and may be 10:1 or less, or 1:1 or less. When alumoxane is used alone as the activating cocatalyst, preferably the number of moles of alumoxane used is at least 100 times the number of moles of the metal-ligand complex of formula (I). When tris(pentafluorophenyl)borane is used alone as the activating cocatalyst, the ratio of the number of moles of tris(pentafluorophenyl)borane used to the total number of moles of the one or more metal-ligand complexes of Formula (I) can be from 0.5:1 to 10:1, from 1:1 to 6:1, or from 1:1 to 5:1. The remaining activating cocatalyst is generally used in a molar amount approximately equal to the total molar amount of the one or more metal-ligand complexes of Formula (I).

[0058] nonwoven fabric Disclosed herein are nonwoven fabrics formed from the bicomponent fibers described above.

[0059] Nonwoven fabrics formed from the bicomponent fibers disclosed herein can be formed via different techniques. Such techniques for forming nonwoven fabrics from the bicomponent fibers disclosed herein include melt spinning, meltblown processes, spunbonding processes, staple processes, carded web processes, airlaid processes, thermal calendering processes, adhesive bonding processes, hot air bonding processes, needlepunching processes, hydroentangling processes, and electrospinning processes. For example, in one embodiment, a spunbond nonwoven fabric can be formed comprising bicomponent fibers according to embodiments disclosed herein. In another embodiment, a meltblown nonwoven fabric can be formed comprising bicomponent fibers according to embodiments disclosed herein.

[0060] Nonwoven fabrics formed from the bicomponent fibers disclosed herein can have a combination of lower denier, enhanced tensile strength, enhanced abrasion resistance, and / or higher elongation at break. In one or more embodiments herein, the nonwoven fabrics have the following properties: a fiber denier of 1.5 g / 9000 m or less (alternatively 1.4 g / 9000 m or less, 1.3 g / 9000 m or less, 1.2 g / 9000 m or less, or in the range of 0.8 to 2 g / 9000 m, 1.0 to 1.8 g / 9000 m, 1.0 to 1.6 g / 9000 m, or 1.0 to 1.4 g / 9000 m), as measured by the test methods described below. A machine direction (MD) tensile strength of greater than 11.0 Newtons per inch (N / in) (alternatively, greater than 13.0 N / in, greater than 15.0 N / in, or greater than 17.0 N / in, or in the ranges of 12.0 to 25 N / in, 13.0 to 25 N / in, 15.0 to 25 N / in, or 18.0 to 25 N / in) for a 20 gsm nonwoven fabric, as measured by the test method described below. A tensile strength of 0.18 mg / cm for a 20 gsm nonwoven fabric, as measured by the test method described below. 2 Less than (alternatively, 0.16 mg / cm 2 Less than 0.14 mg / cm 2 Less than 0.12 mg / cm 2Less than 0.10 mg / cm 2 Less than 0.08 mg / cm 2 Less than 0.06 mg / cm 2 Less than or equal to 0.01 mg / cm 2 ~0.16mg / cm 2 , 0.01 mg / cm 2 ~0.12mg / cm 2 , or 0.01 mg / cm 2 ~0.06mg / cm 2 and a machine direction (MD) abrasion resistance (in the range of 100%), as measured by the test method described below, and a machine direction (MD) abrasion resistance (in the range of 100%), as measured by the test method described below, for a 20 gsm nonwoven, of greater than 100% (alternatively, greater than 120%, greater than 140%, greater than 160%, or in the range of 110% to 200%, 120% to 200%, 140% to 200%, or 160% to 200%).

[0061] For example, nonwoven fabrics according to embodiments disclosed herein may have a machine direction (MD) tensile strength of greater than 11.0 N / 1 in. for a 20 gsm nonwoven fabric, and a machine direction (MD) elongation at break (%) of greater than 100% for a 20 gsm nonwoven fabric. As another example, nonwoven fabrics according to embodiments disclosed herein may have a machine direction (MD) tensile strength of greater than 11.0 N / 1 in. for a 20 gsm nonwoven fabric, and a machine direction (MD) elongation at break (%) of greater than 0.18 mg / cm for a 20 gsm nonwoven fabric. 2 As yet another example, nonwoven fabrics according to embodiments disclosed herein may have a machine direction (MD) tensile strength of greater than 11.0 N / 1 in for a 20 gsm nonwoven fabric, a machine direction (MD) % elongation at break of greater than 100% for a 20 gsm nonwoven fabric, and a machine direction (MD) abrasion resistance of less than 0.18 mg / cm for a 20 gsm nonwoven fabric. 2 It may have a machine direction (MD) abrasion resistance of less than 100%.

[0062] Nonwoven fabrics formed from the bicomponent fibers disclosed herein exhibit a dissolution profile via an improved comonomer composition distribution (ICCD) procedure ranging from 40.0°C to 68.0°C (WT40~68℃ ), the weight percent in the temperature range of 40.0°C to 68.0°C in an elution profile via ICCD can be measured by the test method described below. All individual values ​​and subranges of at least 12 wt% are disclosed and included herein. For example, a nonwoven fabric formed from the bicomponent fibers disclosed herein can include at least 12 wt% of a combination of a first ethylene / alpha-olefin interpolymer and a second ethylene / alpha-olefin interpolymer in an elution profile via an improved comonomer composition distribution (ICCD) procedure from 40.0°C to 68.0°C (WT 40~68℃ ), the weight percent in the temperature range of 40.0 °C to 68.0 °C in the elution profile via ICCD can be measured by the test method described below.

[0063] Nonwoven fabrics formed from the bicomponent fibers disclosed herein exhibit a dissolution profile via an improved comonomer composition distribution (ICCD) procedure ranging from 40.0°C to 65.0°C (WT 40~65℃ ), the weight percent in the temperature range of 40.0°C to 65.0°C in an elution profile via ICCD can be measured by the test method described below. All individual values ​​and subranges of at least 6 weight percent are disclosed and included herein. For example, a nonwoven fabric formed from the bicomponent fibers disclosed herein can include at least 6 weight percent of a combination of the first ethylene / alpha-olefin interpolymer and the second ethylene / alpha-olefin interpolymer in an elution profile via an improved comonomer composition distribution (ICCD) procedure from 40.0°C to 65.0°C (WT 40~65℃), the weight percent in the temperature range of 40.0°C to 65.0°C in the elution profile via ICCD can be measured according to the test method described below.

[0064] Nonwoven fabrics formed from the bicomponent fibers disclosed herein exhibit a dissolution profile via an improved comonomer composition distribution (ICCD) procedure that ranges from 40.0°C to 60.0°C (WT 40~60℃ ), the weight percent in the temperature range of 40.0°C to 60.0°C in an elution profile via ICCD can be measured by the test method described below. All individual values ​​and subranges of at least 2 wt% are disclosed and included herein. For example, a nonwoven fabric formed from the bicomponent fibers disclosed herein can include at least 2 wt% of a combination of the first ethylene / alpha-olefin interpolymer and the second ethylene / alpha-olefin interpolymer in an elution profile via the improved comonomer composition distribution (ICCD) procedure from 40.0°C to 60.0°C (WT 40~60℃ ), the weight percent in the temperature range of 40.0°C to 60.0°C in the elution profile via ICCD can be measured by the test method described below.

[0065] Test Method density Density is measured by ASTM D-792 and is in grams / cm 3 (g / cm 3 )

[0066] Melt Index (I2) Melt index (I2) is measured by ASTM D1238 at 190°C and 2.16 kg and is expressed in grams dissolved / 10 minutes (g / 10 min).

[0067] Conventional Gel Permeation Chromatography (Conventional GPC) The chromatography system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with a built-in IR5 infrared detector (IR5). The autosampler oven compartment was set to 160 °C, and the column compartment was set to 150 °C. The columns used were four Agilent "Mixed A" 30 cm, 20 micron linear mixed-bed columns. The chromatographic solvent used was 1,2,4 trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen-injected. The injection volume used was 200 microliters, and the flow rate was 1.0 milliliters / minute.

[0068] Calibration of the GPC column set is performed using at least 20 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000 g / mol, arranged in six "cocktail" mixtures with at least 10 intervals between individual molecular weights. Standards are purchased from Agilent Technologies. Polystyrene standards are prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000 g / mol, and 0.05 grams in 50 milliliters of solvent for molecular weights less than 1,000,000 g / mol. The polystyrene standards are dissolved at 80°C for 30 minutes with gentle stirring. The polystyrene standard peak molecular weights are converted to ethylene / alpha-olefin interpolymer molecular weights using the following equation (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)): M ポリエチレン =A×(M ポリエチレン ) B (Formula 1) where M is the molecular weight, A has a value of 0.4315, and B is equal to 1.0.

[0069] A fifth-order polynomial is used to fit each ethylene / alpha-olefin interpolymer equivalent calibration point, such as that obtained for NIST standard NBS1475 at a molecular weight of 52,000 g / mol, with a small adjustment to A (approximately 0.39-0.44) to correct for column resolution and band-broadening effects.

[0070] A total plate count of the GPC column set is performed using eicosane (prepared at 0.04 g in 50 milliliters of TCB and dissolved for 20 minutes with gentle agitation). Plate count (Equation 2) and symmetry (Equation 3) are measured with a 200 microliter injection according to the following equations:

[0071]

number

[0072]

number

[0073] Samples are prepared semi-automatically using PolymerChar "Instrument Control" software, which targets a sample weight of 2 mg / ml and adds solvent (containing 200 ppm BHT) to a pre-nitrogen-flushed septa-capped vial via a PolymerChar high-temperature autosampler. Samples are dissolved at 160°C under "slow" shaking for 3 hours.

[0074] M n(GPC) , M w(GPC)、 and M z(GPC) The calculation of is performed using PolymerChar GPCOne™ software, at each equally spaced data collection point i(IR i ) baseline-subtracted IR chromatogram and the ethylene / alpha-olefin interpolymer equivalent molecular weight (M in g / mol) obtained from a narrow standard calibration curve for point i from Equation 1 ポリエチレン、i ) based on the GPC results using the built-in IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 5a-c. Subsequently, the GPC molecular weight distribution (GPC-MWD) plot (wt GPC (lgMW) vs lgMW plot (wt GPCwhere (lgMW) is the weight fraction of interpolymer molecules having a molecular weight of lgMW. Molecular weight is in g / mol, and wt GPC (lgMW) follows equation 4.

[0075]

number

[0076] Number average molecular weight M n(GPC) , weight average molecular weight M w(GPC) and z average molecular weight M z(GPC) can be calculated as follows:

[0077]

number

[0078] To monitor deviations over time, a flow marker (decane) is introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow marker (FM) is used to linearly correct the pump flow rate (Flow Rate (Nominal)) for each sample by aligning the RV of each decane peak in the sample (RV (FM Sample)) with the RV of the decane peak in the narrow standard calibration (RV (FM Calibration)). Any change in time of the decane marker peak was then assumed to be related to a linear shift in flow rate (Flow Rate (Effective)) throughout the experiment. To facilitate the highest accuracy in measuring the RV of the flow marker peaks, a least-squares fitting routine is used to fit the peaks in the flow marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation is then used to solve for the true peak position. After calibrating the system based on the flow marker peaks, the effective flow rate (with respect to the narrow standard calibration) is calculated as in Equation 6. Processing of the flow marker peaks is performed via PolymerChar GPCOne™ software. The allowable flow rate is corrected so that the effective flow rate is within 0.5% of the nominal flow rate. flow rate 実効 = flow rate 公称 ×(RV(FM較正 ) / RV(FM 試料 )) (Formula 6)

[0079] Improved Comonomer Composition Distribution (ICCD) The improved comonomer composition distribution (ICCD) test was performed on a crystallization elution fractionator (CEF) (PolymerChar, Spain) equipped with an IR-5 detector (PolymerChar, Spain) and a two-angle light scattering detector model 2040 (Precision Detectors, currently Agilent Technologies). The ICCD column was packed with gold-coated nickel particles (Bright 7GNM8-NiS, Nippon Chemical Industrial Co.) in a 15 cm (length) x ¼ inch (ID) stainless steel tube. Column packing and conditioning were performed using the slurry method (Cong, R.; Parrott, A.; Hollis, C.; Cheatham, M. WO2017040127A1, incorporated herein by reference). The final pressure of the trichlorobenzene (TCB) slurry packing was 150 bar. The column was installed in the detector oven immediately before the IR-5 detector. Ortho-dichlorobenzene (ODCB, 99% anhydrous or technical grade) is used as the eluent. Silica gel 40 (0.2-0.5 mm particle size, catalog number 10181-3) is obtained from EMD Chemicals and can be used to dry the ODCB solvent. The ICCD instrument is equipped with an autosampler with nitrogen (N2) purging capability. ODCB is used after a 1-hour injection of dry N2. Sample preparation is performed at 4 mg / mL (unless otherwise specified) using the autosampler with shaking at 160 °C for 1 hour. The injection volume is 300 μL. The ICCD temperature profile is crystallization from 105 °C to 30 °C at 3 °C / min, followed by thermal equilibration at 30 °C for 2 minutes (including a 2-minute elution time for the soluble fraction), followed by heating from 30 °C to 140 °C at 3 °C / min. The flow rate during elution is 0.50 mL / min. Data is collected at 1 data point per second. Column temperature calibration was performed using a standard linear homopolymer polyethylene in ODCB (zero comonomer content, melt index (I2) of 1.0 g / 10 min, polydispersity M of approximately 2.6 by conventional gel permeation chromatography at 1.0 mg / ml). w(GPC) / Mn(GPC) This can be done by using a mixture of hydroxybenzoates (having the formula: ##STR1##) and eicosane (2 mg / ml). The ICCD temperature calibration consists of four steps: (1) calculating the delay volume, defined as the temperature offset between the measured peak elution temperature of eicosane minus 30.00°C; (2) subtracting the temperature offset of the elution temperature from the raw ICCD temperature data (note that this temperature offset is a function of experimental conditions such as elution temperature and elution flow rate); (3) constructing a linear calibration line that converts elution temperatures ranging from 30.00°C to 140.00°C so that a linear homopolymer polyethylene standard has a peak temperature at 101.0°C and eicosane has a peak temperature of 30.0°C; and (4) linearly extrapolating elution temperatures below 30.0°C using an elution heating rate of 3°C / min according to the literature (Cerk and Cong et al., US Pat. No. 9,688,795, incorporated herein by reference) for the soluble fraction measured isothermally at 30°C.

[0080] Determination of weight percent in ICCD elution profiles A single baseline is subtracted from the IR measurement signal to generate a relative mass-dissolution profile plot starting and ending at zero relative mass at the lowest and highest dissolution temperatures (typically 35°C to 119°C). For convenience, this is presented as a quantity normalized to a total area equivalent to 1. In the relative mass-dissolution profile plot from the ICCD, the weight fraction (w) at each temperature (T) is plotted. T (T)) (which can be converted to weight percent) can be obtained. A temperature profile (w T (T) vs. T), as follows:

[0081]

number

[0082] Weight fraction (WT より低いT-より高いT ) is wT By integrating the (T) vs. T profile over the temperature range of interest, the following equation can be calculated:

[0083]

number

[0084] Tensile Strength and Elongation at Break % Test Method For tensile testing, 20 grams per square meter (gsm) nonwoven fabric is cut into 1 inch x 8 inch rectangular strips in the machine direction (MD) for tensile testing using an Instron tensile tester. The strips are tested at a test speed of 300 mm / min with an initial grip distance (L0) of 76.2 mm. The nonwoven fabric tensile strength in Newtons per inch (N / inch width) is determined at the peak force. At the peak load, the grip distance (L) is read and the elongation at break (%) is reported as (L-L0) / L0 x 100%. The average value of five samples is reported.

[0085] Abrasion resistance test method The abrasion resistance of exemplary nonwoven fabrics can be measured using a Sutherland Ink Rub Tester. Prior to testing, a 20 gsm nonwoven fabric sample is cut into a 12.5 cm x 5 cm rectangular strip and conditioned at 73°F + / - 2 and constant relative humidity for a minimum of 4 hours. A 12.5 cm x 5 cm rectangular strip of 320 grit aluminum oxide cloth sandpaper is then attached to the Sutherland Ink Rub Tester. The sample is then weighed to the nearest 0.01 mg and mounted on the tester. A 2 lb weight is then attached to the Sutherland Ink Rub Tester, and the tester is run for 20 cycles at a speed of 42 cycles per minute. Loose fibers are removed using adhesive tape, and the sample is reweighed to determine the amount of material lost. Abrasion resistance is defined as the weight loss of the material divided by the size of the abraded area of ​​fuzz. The unit of abrasion resistance is mg / cm. 2 The average value of five samples is reported.

[0086] Fiber Denier Measurement Fiber diameter is measured under an optical microscope. Denier (defined as the weight of such a fiber per 9000 meters) is calculated based on the density of each polymer component and the fiber diameter.

[0087] Determination of filament velocity The filament velocity is calculated based on the following formula: Filament speed (meters / min) = Processing speed (g / min) / Denier (g / 9000m) * 9,000 (Equation 9).

[0088] Differential scanning calorimetry (DSC) Differential scanning calorimetry is used to measure the maximum peak melting temperature (Tm) and maximum peak crystallization temperature (Tc) according to ASTM D3895-14. Approximately 0.5 grams of sample is compression molded into a film at 25,000 psi and 190°C for 10-15 seconds. 5-8 mg of sample is weighed and placed into a DSC aluminum pan, and a lid is crimped onto the pan to ensure a sealed atmosphere. A nitrogen purge gas flow rate of 50 ml / min is used during testing.

[0089] The thermal behavior of the sample is determined by raising and lowering the sample temperature to generate a heat flow versus temperature profile. For cooling and second thermal information, the sample is heated at a rate of 10°C / min to 150°C and held isothermal for 5 minutes. The sample is then cooled at a rate of 10°C / min to -40°C, held isothermal for 5 minutes, and then heated at a rate of 10°C / min to 150°C.

[0090] A cooling curve and a second heating curve are recorded. The cooling curve is analyzed by setting a baseline endpoint from the onset of crystallization to -20°C. The heating curve is analyzed by setting a baseline endpoint from -20°C to the end of melting. The values ​​measured are the maximum peak melting temperature (Tm) and the maximum peak crystallization temperature (Tc). The maximum peak melting temperature (Tm) is reported from the second heating curve. The maximum peak crystallization temperature (Tc) was determined from the cooling curve. [Example]

[0091] Preparation of Example Ethylene / Alpha-Olefin Interpolymers Polymer 1 (Poly.1), Polymer 2 (Poly.2), and Polymer 3 (Poly.3), which are ethylene / alpha-olefin interpolymers, are prepared by the following process and table.

[0092] All raw materials (monomers and comonomers) and process solvents (high-purity narrow-boiling range isoparaffinic solvent, Isopar-E) are purified with molecular sieves before being introduced into the reaction environment. Hydrogen is supplied under pressure as a high-purity grade and is not further purified. The reactor monomer feed stream is pressurized to a pressure above the reaction pressure by a mechanical compressor. Solvent and comonomer (if present) feeds are pressurized above the reaction pressure via pumps. Individual catalyst components are manually batch diluted with purified solvent and pressurized above the reaction pressure. All reaction feed streams are metered using mass flow meters and independently controlled by computer-automated valve control systems.

[0093] The reactor configuration is either a single reactor operation or a dual reactor in series operation as specified in Tables 2A and 2B below.

[0094] Either a single reactor system or a two-reactor system in series configuration is used. Each reactor is a continuous solution polymerization reactor consisting of a liquid-filled, non-adiabatic, isothermal circulating loop reactor, replicating a heat-removing continuous stirred tank reactor (CSTR). Independent control of all fresh solvent, monomer, comonomer (if present), hydrogen, and catalyst component feeds is possible. The total fresh feed stream to each reactor (solvent, monomer, comonomer (if present), and hydrogen) is temperature-controlled, typically between 15 and 50°C, to maintain a single solution phase by passing the feed stream through a heat exchanger. The total fresh feed to each polymerization reactor is injected into the reactor at two locations, with approximately equal reactor volume between each injection location. The fresh feed is controlled so that each injector receives half of the total fresh feed mass flow rate. Catalyst components are injected into the polymerization reactor through injection nozzles, introducing the components into the center of the reactor flow. The primary catalyst component feed is computer-controlled to maintain reactor monomer conversion at a specific value. The cocatalyst component is fed to the main catalyst component based on a calculated specific molar ratio. Immediately after the injection point of each reactor feed, the feed stream is mixed with the contents of a circulation polymerization reactor with static mixing elements. The contents of each reactor are continuously circulated through a heat exchanger that serves to remove the majority of the heat of reaction, with the coolant side temperature serving to maintain an isothermal reaction environment at a specific temperature. Circulation around each reactor loop is provided by a pump.

[0095] In a dual reactor-in-series configuration, the effluent from the first polymerization reactor (containing solvent, monomer, comonomer (if present), hydrogen, catalyst components, and polymer) exits the first reactor loop and is added to the second reactor loop. In all reactor configurations, the final reactor effluent (either the second reactor effluent in the dual reactor series configuration, or the single reactor effluent) enters a zone where it is deactivated by adding and reacting with a suitable reagent (water). At the exit point of this same reactor, other additives are added for polymer stabilization (e.g., antioxidants suitable for stabilization during extrusion and fabrication include octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis(methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate))methane, and tris(2,4-di-tert-butyl-phenyl)phosphite).

[0096] Following catalyst deactivation and additive addition, the reactor effluent enters a devolatilization system where polymer is removed from the non-polymer stream. The isolated polymer melt is pelletized and collected. The non-polymer stream passes through various equipment that separates most of the ethylene removed from the system. Most of the solvent and unreacted comonomer (if present) are recycled to the reactor after passing through a purification system. Small amounts of solvent and comonomer (if present) are purged from the process.

[0097] The reactor stream feed data flows used to produce the polymer, corresponding to the values ​​in Tables 2A and 2B, are illustrated graphically in Figures 1 and 2. The data are presented in a way that takes into account the complexity of the solvent recycle system and allows the reaction system to be more easily treated as a once-through flow diagram.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] The following ethylene / alpha-olefin interpolymers are also used in the examples:

[0102] Polymer 4 (Poly. 4) is ASPUN™ 6850A, an ethylene / alpha-olefin interpolymer commercially available from The Dow Chemical Company (Midland, MI).

[0103] Polymer 5 (Poly. 5) is ASPUN™ 6835A, an ethylene / alpha-olefin interpolymer commercially available from The Dow Chemical Company (Midland, MI).

[0104] Polymer 6 (Poly. 6) is ASPUN™ 6000, an ethylene / alpha-olefin interpolymer commercially available from The Dow Chemical Company (Midland, MI).

[0105] Polymer 7 (Poly. 7) is DOWLEX™ 2517, an ethylene / alpha-olefin interpolymer commercially available from The Dow Chemical Company (Midland, MI).

[0106] Polymer 8 (Poly. 8) is ELITE™ 5860, an ethylene / alpha-olefin interpolymer commercially available from The Dow Chemical Company (Midland, MI).

[0107] Table 3 below shows the melt index (I2), density, and Mw of Poly.1 to Poly.8. (GPC) / Mn (GPC), the maximum peak crystallization temperature (Tc), and the maximum peak melting temperature (Tm).

[0108] [Table 4]

[0109] Fiber and nonwoven fabric formation Spunbond nonwoven fabrics were formed from bicomponent fibers and produced on a single-beam Reicofil4 spunbond line in a 50:50 (weight percent) core:sheath bicomponent configuration. The core of the bicomponent fiber was an ethylene / alpha-olefin interpolymer composition as reported in Table 4. The sheath was the same or a different ethylene / alpha-olefin interpolymer composition as reported in Table 4. The machine (Reicofil4 spunbond line) was equipped with a spinneret with 7022 holes (6861 holes / m) and an exit diameter of each hole of 0.6 mm. The hole L / D ratio was 4. The polymer melt temperature was set at approximately 230°C. The fibers were collected at the maximum sustainable cabin air pressure while maintaining stable fiber spinning and converted into a nonwoven fabric with a target basis weight of 20 gsm. Web bonding was achieved between an imprinted roll and a smooth roll (with a nip pressure of 70 daN / cm). The oil temperature of the engraved roll is adjusted to achieve the best bond without the nonwoven fabric covering the roll. The oil temperature of the smooth roll is kept 2°C lower than the oil temperature of the engraved roll.

[0110] Exemplary nonwoven fabrics formed from bicomponent fibers are shown as inventive and comparative examples, as reported in Table 4. The fiber denier of the nonwoven fabrics, as well as the difference in maximum peak melting temperature (ΔTm), difference in maximum peak crystallization temperature (ΔTc), and difference in density (ΔDensity) between the first and second regions of the bicomponent fiber, are reported in Table 5.

[0111] 40.0°C to 68.0°C (WT) in the ICCD profile of the nonwoven fabric example 40~68℃ ), 40.0℃~65.0℃(WT 40~65℃ ), and 40.0℃~60.0℃(WT40~60℃ The combined weight percent (wt %) of the first ethylene / alpha-olefin interpolymer and the second ethylene / alpha-olefin interpolymer is reported in Table 6. Referring now generally to Figure 3, an ICCD elution profile for the nonwoven fabric of inventive Example 2 is shown. The combined weight percent of Poly.3 and Poly.8 of inventive Example 2 exhibited a significant increase in the ICCD elution profile from 40.0°C to 68.0°C (WT 40~68℃ ) temperature range, is equal to 30% (as reported in Table 6). The nonwoven fabrics of the present invention, Inventive Example 1 and Inventive Example 2 have a higher weight percentage of the two polymers in the region on the ICCD elution profile, which, without being bound by theory, contributes to the enhanced properties of abrasion resistance, tensile strength, and / or elongation at break.

[0112] Additional processing conditions for the nonwoven fabrics are reported in Table 7. Additional properties of the nonwoven fabrics are shown in Table 8. Without being bound by theory, the nonwoven fabrics of the present invention, Inventive Example 1, and Inventive Example 2 have higher ΔTm, ΔTc, and Δdensity while having finer fiber denier compared to Comparative Examples 1-8, which contribute to enhanced properties of abrasion resistance, tensile strength, and / or elongation at break.

[0113] [Table 5]

[0114] [Table 6]

[0115] [Table 7]

[0116] [Table 8]

[0117] [Table 9]

[0118] All documents cited herein, including any cross-referenced or related patents or applications, if any, and any patent application or patent to which this application claims priority or benefit, are incorporated herein by reference in their entirety, unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein, or that it teaches, suggests, or discloses such invention, either alone or in any combination with any other reference. Furthermore, to the extent that the meaning or definition of any term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0119] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended in the appended claims to cover all such changes and modifications that are within the scope of this invention. It should be noted that the present invention includes the following aspects. [Aspect 1] A bicomponent fiber, comprising a first region and a second region; the first region comprises a first ethylene / alpha-olefin interpolymer having a maximum peak melting temperature (Tm) of less than 130°C as measured by DSC; the second region comprises a second ethylene / alpha-olefin interpolymer having a density less than a density of the first ethylene / alpha-olefin interpolymer composition; the highest peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer is at least 3.5°C higher than the highest peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer, wherein the highest peak melting temperature (Tm) is measured by DSC; A bicomponent fiber, wherein the first region and second region are arranged in a core-sheath configuration. [Aspect 2] 2. The bicomponent fiber of embodiment 1, wherein the first ethylene / alpha-olefin interpolymer has a maximum peak crystallization temperature (Tc) that is at least 3.5° C. higher than the maximum peak crystallization temperature (Tc) of the second ethylene / alpha-olefin interpolymer, wherein the maximum peak crystallization temperature (Tc) is measured by DSC. [Aspect 3] the density of the first ethylene / alpha-olefin interpolymer is at least 0.022 g / cm greater than the density of the second ethylene / alpha-olefin interpolymer; 3 3. The bicomponent fiber of claim 1 or 2. [Aspect 4] A nonwoven fabric formed from the bicomponent fibers of any one of claims 1-3, wherein the nonwoven fabric has the following properties: a fiber denier of 1.5 g / 9000 m or less; a machine direction tensile strength of greater than 11.0 Newtons per inch for a 20 gsm nonwoven fabric; a machine direction elongation at break of greater than 100% for a 20 gsm nonwoven fabric; and a machine direction elongation at break of 0.18 mg / cm for a 20 gsm nonwoven fabric.2 A nonwoven fabric formed from bicomponent fibers having one or more of the following machine direction abrasion resistances: [Aspect 5] A nonwoven fabric formed from the bicomponent fibers of any one of claims 1-3, wherein the nonwoven fabric has an elution profile via an improved comonomer composition distribution (ICCD) procedure that exhibits a densitometric value of 40.0°C to 68.0°C (WT 40~68℃ ) temperature range, wherein the nonwoven fabric is formed from bicomponent fibers comprising at least 12 wt. % of a combination of a first ethylene / alpha-olefin interpolymer and a second ethylene / alpha-olefin interpolymer. [Aspect 6] A nonwoven fabric formed from the bicomponent fibers of any one of claims 1-3, wherein the nonwoven fabric has a fiber denier of 1.5 g / 9000 m or less, a machine direction tensile strength of greater than 11.0 Newtons per inch for a 20 gsm nonwoven fabric, a machine direction elongation at break of greater than 100% for a 20 gsm nonwoven fabric, and a machine direction elongation at break of 0.18 mg / cm for a 20 gsm nonwoven fabric. 2 A nonwoven fabric formed from bicomponent fibers having a machine direction abrasion resistance of less than 100%.

Claims

1. A nonwoven fabric formed from bicomponent fibers, the bicomponent fiber comprises a first region and a second region; the first region comprises a first ethylene / alpha-olefin interpolymer having a highest peak melting temperature (Tm) of less than 130°C as measured by DSC; the second region comprises a second ethylene / alpha-olefin interpolymer having a density less than a density of the first ethylene / alpha-olefin interpolymer composition; the highest peak melting temperature (Tm) of the first ethylene / alpha-olefin interpolymer is at least 3.5° C. higher than the highest peak melting temperature (Tm) of the second ethylene / alpha-olefin interpolymer, wherein the highest peak melting temperature (Tm) is measured by DSC; the first region and the second region are arranged in a core-sheath configuration; a weight ratio of the first region to the second region of 60:40 to 40:60; the nonwoven fabric comprises at least 12 weight percent of a combination of the first ethylene / alpha-olefin interpolymer and the second ethylene / alpha-olefin interpolymer in an elution profile via an improved comonomer composition distribution (ICCD) procedure at a temperature range of 40.0°C to 68.0°C (WT 40-68°C); The nonwoven fabric has a fiber denier of 1.5 g / 9000 m or less, a machine direction tensile strength of greater than 11.0 Newtons per inch (2.54 cm) at 20 grams per square meter (gsm) of the nonwoven fabric, a machine direction elongation to break of greater than 100% at 20 gsm of the nonwoven fabric, and a machine direction abrasion resistance of less than 0.18 mg / cm2 at 20 gsm of the nonwoven fabric.

2. 10. The nonwoven fabric of claim 1, wherein the first ethylene / alpha-olefin interpolymer has a maximum peak crystallization temperature (Tc) that is at least 3.5°C higher than the maximum peak crystallization temperature (Tc) of the second ethylene / alpha-olefin interpolymer, wherein the maximum peak crystallization temperature (Tc) is measured by DSC.

3. the density of the first ethylene / alpha-olefin interpolymer is at least 0.022 g / cm greater than the density of the second ethylene / alpha-olefin interpolymer. ３ The nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric has a high viscosity.

4. A nonwoven fabric described in any one of claims 1 to 3, wherein the weight ratio of the first region to the second region is 55:45 to 45:

55.

5. The nonwoven fabric has an elution profile via an improved comonomer composition distribution (ICCD) procedure that is 40.0°C to 68.0°C (WT ４０～６８℃ 5. The nonwoven fabric of claim 1, comprising 13 to 30 weight percent of a combination of the first ethylene / alpha-olefin interpolymer and the second ethylene / alpha-olefin interpolymer at a temperature range of 13 to 30°C.

6. The nonwoven fabric has a fiber denier of 1.1 to 1.4 g / 9000 m, a machine direction tensile strength of 13.6 to 18.0 Newtons per inch (2.54 cm) for a 20 gsm nonwoven fabric, a machine direction elongation at break of 120% to 163% for a 20 gsm nonwoven fabric, and a fiber density of 0.05 to 0.10 mg / cm for a 20 gsm nonwoven fabric. ２ The nonwoven fabric of any one of claims 1 to 5, having a machine direction abrasion resistance of

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