Bicomponent Fibers with Curvature

Abstract

A bicomponent fiber having curvature is provided. The bicomponent fiber includes a first region and a second region. The first region includes a polypropylene blend and the second region includes an ethylene / alpha-olefin interpolymer composition. The polypropylene blend includes a polypropylene homopolymer and a propylene-ethylene interpolymer, the propylene-ethylene interpolymer having a density of 0.860 to 0.880 g / cc and a melt flow rate of greater than 12 g / 10 min. The ethylene / alpha-olefin interpolymer composition has a density of greater than 0.920 g / cc and a melt index (I2) of 10 to 25 g / 10 min. The bicomponent fiber can be used to form a nonwoven fabric.

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure generally relate to bicomponent fibers having curvature and nonwoven fabrics including the fibers. [Background technology]

[0002] Introduction Bicomponent fibers are fibers composed of at least two different polymer compositions extruded from the same spinneret, the compositions being contained within the same filament or fiber. When the fiber leaves the spinneret, it is composed of unmixed 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 conventional spinning techniques known in the art and can be used to form nonwoven fabrics. Nonwoven fabrics have a variety of applications, including filters, disposable materials for medical applications, and diaper stock. Bicomponent fibers with curvature are desirable to help reduce the weight of nonwoven fabrics and obtain other advantageous nonwoven properties, such as loft. However, problems exist in obtaining bicomponent fibers with curvature, and there is still a demand for nonwoven fabrics with loft and fibers with improved curvature. Summary of the Invention

[0003] The present disclosure provides a bicomponent fiber that can be used to form a nonwoven fabric and provides a surprisingly high curvature in an aspect. The bicomponent fiber according to the present disclosure includes a first region and a second region, which contribute to improving the curvature of the fiber. Specifically, the bicomponent fiber according to the present disclosure includes a polypropylene blend and an ethylene / alpha-olefin interpolymer composition that can increase the curvature of the fiber when it is part of the fiber in a specific weight ratio.

[0004] Disclosed herein is a bicomponent fiber. In one embodiment, the bicomponent fiber includes a fiber centroid, a first region having a first centroid and a second region having a second centroid, the first region includes a polypropylene blend including 50-90 wt% polypropylene homopolymer based on the total weight of the polypropylene blend and 10-50 wt% propylene-ethylene interpolymer based on the total weight of the polypropylene blend, the propylene-ethylene interpolymer having a density of 0.860-0.880 g / cc and a melt flow rate of more than 12 g / 10 min, the second region includes an ethylene / alpha-olefin interpolymer composition having a density of more than 0.920 g / cc and a melt index (I2) of 10-25 g / 10 min, at least one of the first centroid and the second centroid is not the same as the fiber centroid, and the weight ratio of the first region to the second region is 55:45-90:10.

[0005] Also disclosed herein are nonwoven fabrics formed from the bicomponent fibers disclosed herein. For example, a nonwoven fabric can be formed from the bicomponent fibers disclosed herein. In one embodiment, the nonwoven fabric comprises a fiber centroid, a first region having a first centroid and a second region having a second centroid, the first region comprising a polypropylene blend comprising 50-90 wt.% polypropylene homopolymer based on the total weight of the polypropylene blend and 10-50 wt.% propylene-ethylene interpolymer based on the total weight of the polypropylene blend, the propylene-ethylene interpolymer having a density of 0.860-0.880 g / cc and a melt flow rate of greater than 12 g / 10 min, the second region comprising an ethylene / alpha-olefin interpolymer composition having a density of greater than 0.920 g / cc and a melt index (I2) of 10-25 g / 10 min, at least one of the first centroid and the second centroid is not the same as the fiber centroid, and the weight ratio of the first region to the second region is from 55:45 to 90:10.

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

[0007] It should be understood that both the foregoing and the following description are intended to describe various embodiments and provide an overview or framework for understanding the nature and features of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter. [Brief description of the drawings]

[0008] [Figure 1] 1 is a scanning electron micrograph (SEM) cross-sectional image of a bicomponent fiber having an eccentric core-sheath configuration and a center of gravity offset. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Aspects of the disclosed bicomponent fibers are described in more detail below. The bicomponent fibers having curvature can be used to form nonwoven fabrics, which can have a wide variety of applications, including, for example, wipes, face masks, tissues, bandages, and other medical and hygiene products. However, it should be noted that this is merely an exemplary implementation of the embodiments disclosed herein. The embodiments are also applicable to other technologies that are 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 components, steps, or procedures, whether they are specifically disclosed or not. For the avoidance of any doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding 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 polymers 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 generic term polymer encompasses the terms 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 interpolymer. Minor amounts of impurities (e.g., catalyst residues) may be incorporated into and / or within the polymer. The polymer may be a single polymer or a polymer blend.

[0013] As used herein, the term "polyethylene" refers to a polymer containing more than 50% by weight of units derived from ethylene monomers and, optionally, one or more comonomers. Polyethylene includes polyethylene homopolymers, copolymers, or interpolymers. Common forms of polyethylene compositions known in the art include, but are not limited to, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), single-site catalyzed linear low density polyethylene (m-LLDPE), including both linear low density resins and substantially linear low density resins, medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0014] 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 identifiable manner as in knitted fabrics.

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

[0016] As used herein, the term "spunbond" refers to the manufacture of a nonwoven fabric that includes the steps of: (a) extruding molten thermoplastic strands from a plurality of fine capillaries called spinnerets; (b) quenching the strands of thermoplastic strands, for example comprising a polyethylene composition, typically by a chilled air stream to speed the solidification of the molten strands of thermoplastic material; (c) attenuating the filaments by advancing them through a quench zone under a drawing tension, which can be applied by pneumatically entraining the filaments in the 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 accomplished by a variety of means, including, but not limited to, thermal calendering, adhesive bonding, hot air bonding, needle punching, hydroentangling, and combinations thereof.

[0017] Bicomponent Fiber The fibers taught herein can be formed by any conventional spinning technique. For example, the first and second regions of the bicomponent fiber can be formed into a fiber via melt spinning. In melt spinning, the first and second regions can be melted, co-extruded, and forced through fine orifices in a metal plate called a spinneret into air or other gas where they are cooled and solidified to form the bicomponent fiber. The solidified fiber can be drawn through an air jet, a rotating roll, or a godet, and can be laid on a conveyor belt as a web to form a nonwoven fabric. Meltblown nonwoven fabrics can be formed that include bicomponent fibers according to embodiments of the present disclosure. In other embodiments, spunbond nonwoven fabrics can be formed that include bicomponent fibers according to embodiments of the present disclosure.

[0018] The fibers disclosed herein have curvature.

[0019] In some embodiments, the bicomponent fiber has a thickness of at least 0.50 mm. -1 The curvature of a bicomponent fiber can be measured by the test method described below. -1 For example, in some embodiments, the bicomponent fiber has a cross section of at least 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.20, 1.40, 1.60, 1.80, 2.00, 2.20, 2.40, or 2.50 mm, as measured by the test methods described below. -1 In other embodiments, the bicomponent fibers can have a curvature of 0.50 to 4.50, 1.00 to 4.50, 1.50 to 4.50, 2.00 to 4.50, 2.50 to 4.50, 3.00 to 4.50, 1.00 to 4.20, 1.50 to 4.20, 2.00 to 4.20, or 2.50 to 4.20 mm when measured according to the test methods described below. -1 The curvature can be in the range of

[0020] In some 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 55:45 to 90:10. All individual values ​​and subranges of the ratio from 55:45 to 90:10 are disclosed and included herein. For example, in embodiments, the weight ratio of the first region to the second region can be from 60:40 to 90:10, from 70:30 to 90:10, from 80:20 to 90:10, or from 55:45 to 80:20.

[0021] In some embodiments, the bicomponent fiber further comprises a third region comprising a different polymer than that of the first and second regions, hi embodiments, the bicomponent fiber further comprises a third and fourth region, the third and fourth regions comprising a different polymer than that of the first and second regions.

[0022] center of gravity In some embodiments, a bicomponent fiber includes a fiber center of gravity and a first region having a first center of gravity and a second region having a second center of gravity, where at least one of the first center of gravity and the second center of gravity is not the same as the fiber center of gravity.

[0023] As used herein, the term "center of gravity" refers to the arithmetic average of all points of the area of ​​the cross section of a bicomponent fiber. For example, a bicomponent fiber according to an embodiment of the present disclosure may have a center of gravity of C f and the bicomponent fiber region (e.g., the first or second region) has a fiber center of gravity that may be denoted as C rx (wherein x is a designation for a region) (e.g., the first region is C r1 The second area is sometimes written as C r2 FIG. 1 shows a bicomponent fiber and its center of gravity, as well as the centers of gravity of the first and second regions of the bicomponent fiber. The distance from the region center of gravity to the fiber center of gravity is referred to as "P rx " and the centroid offset of the first centroid or the second centroid with respect to the fiber centroid can be defined as "P rx / r" [wherein "r" is the average radius of the fiber cross section (C f (average distance from the outer surface of the bicomponent fiber to the

[0024]

number

[0025] In some embodiments, at least one of the first and second centroids is not the same as the fiber centroid. If the first or second centroid is different from the fiber centroid, the bicomponent fiber may have a different configuration, such as eccentric core-sheath, side-by-side, or segmented pie, but cannot have a concentric configuration in which the fiber centroid, the first centroid, and the second centroid are the same (e.g., core-sheath concentric configuration). In embodiments, the first centroid of the first region and the second centroid of the second region are arranged such that the first region and the second region are in a side-by-side configuration. In other embodiments, the first centroid of the first region and the second centroid of the second region are arranged such that the first region and the second region are in a segmented pie configuration. In further embodiments, the first center of gravity of the first region and the second center of gravity of the second region are arranged such that the first region and the second region are in an eccentric core-sheath configuration, with the first region of the bicomponent fiber being the core region and the second region being the sheath region, with the sheath region surrounding the core region. In embodiments, the first and second regions are arranged in a core-sheath, side-by-side, split pie, or islands-in-the-sea configuration.

[0026] In some embodiments, the first center of gravity or the second center of gravity is offset from the fiber center of gravity by at least 0.1, or at least 0.2, or at least 0.4, and less than 1, or less than 0.9, where the offset is measured according to the test method described below.

[0027] First Area The bicomponent fiber includes a first region. The first region can be a core region in a core-sheath bicomponent fiber. The first region has a first center of gravity. The first region includes a polypropylene blend. In some embodiments, the polypropylene blend includes a polypropylene homopolymer and a propylene-ethylene interpolymer. In some embodiments, the polypropylene blend of the first region includes 50-90 wt% polypropylene homopolymer based on the total weight of the polypropylene blend. All individual values ​​between 50-90 wt% are disclosed and included herein. For example, the first region can include a polypropylene blend including 55-90 wt%, 60-90 wt%, 65-90 wt%, 65-85 wt%, 65-80 wt%, 50-85 wt%, 50-80 wt%, or 50-75 wt% polypropylene homopolymer based on the total weight of the polypropylene blend.

[0028] In some embodiments, the polypropylene blend comprises 10-50 wt% propylene-ethylene interpolymer based on the total weight of the polypropylene blend. All individual values ​​and subranges between 10-50 wt% are disclosed and included herein. For example, the polypropylene blend may comprise 10-40 wt%, 10-35 wt%, 15-45 wt%, 15-50 wt%, 20-40 wt%, 25-50 wt%, or 25-35 wt% propylene-ethylene interpolymer based on the total weight of the polypropylene blend. As used herein, the term "propylene-ethylene interpolymer" refers to an interpolymer comprising greater than 50 wt% propylene monomer units copolymerized with at least ethylene monomer derived units.

[0029] In some embodiments, the propylene-ethylene interpolymer of the polypropylene blend has a density of 0.860 to 0.880 g / cc. All individual values ​​and subranges between 0.860 and 0.880 g / cc are disclosed and included herein. For example, the propylene-ethylene interpolymer may have a density of 0.860 to 0.878 g / cc, 0.862 to 0.878 g / cc, 0.864 to 0.878 g / cc, 0.865 to 0.878 g / cc, 0.867 to 0.876 g / cc, or 0.867 to 0.874 g / cc, where density can be measured according to ASTM D792.

[0030] In some embodiments, the propylene-ethylene interpolymer of the polypropylene blend has a melt flow rate greater than 12 g / 10 min, the melt flow rate being measured according to ASTM D-1238 at 230° C. and 2.16 kg. All individual values ​​and subranges greater than 12 g / 10 min are disclosed and included herein. For example, the propylene-ethylene interpolymer may have a melt flow rate of greater than 14 g / 10 min, greater than 16 g / 10 min, greater than 18 g / 10 min, greater than 20 g / 10 min, greater than 22 g / 10 min, or greater than 24 g / 10 min, or may have a melt flow rate in the range of 14 to 50 g / 10 min, 20 to 48 g / 10 min, 22 to 46 g / 10 min, 24 to 44 g / 10 min, 22 to 40 g / 10 min, or 24 to 40 g / 10 min, the melt flow rate being measured at 230° C. and 2.16 kg according to ASTM D-1238.

[0031] At least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or at least 100% of the first region of the fiber (all percentages are weight percentages based on the total weight of the first region) can be a propylene blend. The remaining portion of the first region can be additional components such as one or more other polymers and / or one or more additives. The other polymer can be another propylene-based polymer or polyethylene. The amount of other polymer can be up to 25%. Possible additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers such as TiO2 or CaCO3, opacifiers, nucleating agents, processing aids, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antimicrobial agents, odor reducing agents, antifungal agents, and combinations thereof. The polypropylene blend may contain from about 0.01, or about 0.1, or about 1 weight percent to about 25, or about 20, or about 15, or about 10 weight percent total weight of such additives, based on the weight of the propylene blend including such additives.

[0032] Second Area The bicomponent fiber includes a second region. The second region can be a sheath region in a bicomponent fiber with an eccentric core-sheath configuration. The second region has a second center of gravity. In some embodiments, the second region includes an ethylene / alpha-olefin interpolymer composition. In some embodiments, the ethylene / alpha-olefin interpolymer composition has a density greater than 0.920 g / cc and a melt index (I2) of 10 to 25 g / 10 min.

[0033] As used herein, the term "ethylene / alpha-olefin interpolymer composition" refers to an interpolymer comprising a majority amount of ethylene monomer and at least one alpha-olefin monomer in polymerized form (based on the weight of the interpolymer). The ethylene / alpha-olefin interpolymer composition comprises (a) less than 100 weight percent, e.g., at least 80 weight percent, or at least 90 weight percent, of units derived from ethylene, and (b) less than 20 weight percent, e.g., less than 15 weight percent, or less than 10 weight percent, of units derived from one or more alpha-olefin comonomers. The alpha-olefin comonomer typically has 20 or fewer carbon atoms. For example, the alpha-olefin comonomer may preferably have 3 to 10 carbon atoms, more preferably 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 α-olefin comonomers may, for example, be selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene, or alternatively, may be selected from the group consisting of 1-hexene and 1-octene.

[0034] In some embodiments, the ethylene / alpha-olefin interpolymer composition has a density greater than 0.920 g / cc. All individual values ​​and subranges greater than 0.920 g / cc are disclosed and included herein. For example, the ethylene / alpha-olefin interpolymer composition can have a density greater than 0.925 g / cc, or greater than 0.930 g / cc, or greater than 0.935 g / cc, or a density in the range of 0.925-0.965 g / cc, or 0.930-0.965 g / cc, or 0.925-0.960 g / cc, 0.925-0.955 g / cc, 0.925-0.950 g / cc, 0.930-0.960 g / cc, 0.930-0.955 g / cc, or 0.930-0.950 g / cc, where density can be measured according to ASTM D792.

[0035] In some embodiments, the ethylene / alpha-olefin interpolymer composition has a melt index (I2) of 10 to 25 g / 10 min, where the melt index (I2) is measured according to ASTM D-1238 at 190° C. and 2.16 kg. All individual values ​​and subranges from 10 to 25 g / 10 min are disclosed and included herein. For example, the ethylene / alpha-olefin interpolymer composition can have a melt index (I2) of 10-24 g / 10 min, 10-23 g / 10 min, 10-22 g / 10 min, 10-21 g / 10 min, 10-20 g / 10 min, 10-18 g / 10 min, 10-16 g / 10 min, 12-24 g / 10 min, 14-25 g / 10 min, 16-25 g / 10 min, 18-25 g / 10 min, or 17-25 g / 10 min, where the melt index (I2) is measured at 190° C. and 2.16 kg according to ASTM D-1238.

[0036] In some embodiments, the ethylene / alpha-olefin interpolymer composition has a density in the range of 0.930 to 0.965 g / cc, a melt index (I2) in the range of 10 to 25 g / 10 min, and a ratio of weight average molecular weight to number average molecular weight (M) as determined by GPC in the range of 1.5 to 2.6. w(GPC) / M n(GPC) ), a loss tangent at 1 rad / sec of at least 45, and a low temperature peak and a high temperature peak in an improved comonomer composition distribution (ICCD) elution profile from a crystallization elution fraction between 35°C and 110°C, with the high temperature peak having a full width at half maximum of less than 6.0°C.

[0037] The ethylene / alpha-olefin interpolymer composition may have an I10 / I2 ratio of less than 6.9, or less than 6.8, or less than 6.7, where I10 is measured at 190° C. and 10 kg according to ASTM D1238. A lower I10 / I2 ratio may indicate less long chain branching, which leads to better spinnability / processability.

[0038] The ethylene / alpha-olefin interpolymer composition has a ratio of weight average molecular weight to number average molecular weight (M w(GPC) / M n(GPC) The interpolymer compositions having a molecular weight distribution in this range are believed to have better processability (e.g., fiber spinning) than interpolymers having higher molecular weight distributions. Ethylene / alpha olefin interpolymers have an M greater than (I10 / I2)-4.63. w(GPC) / M n(GPC) It can be characterized by:

[0039] The ethylene / alpha-olefin interpolymer composition can have a weight average molecular weight from a lower limit of 15,000 g / mol, 20,000 g / mol, or 30,000 g / mol to an upper limit of 100,000 g / mol, 120,000 g / mol, or 150,000 g / mol. z(GPC) / M w(GPC) can be less than 3.0 or less than 2.0 and greater than 1.0. The ethylene / alpha-olefin interpolymer composition can be a bimodal polymer composition having two peaks in the ICCD elution profile. In that case, the high temperature fraction can have a peak position molecular weight of 70,000 g / mol or less, or 50,000 g / mol or less. The high temperature fraction can have a peak position molecular weight of at least 15,000 or at least 20,000 g / mol. The low temperature fraction can have a peak position molecular weight of at least 30000, or at least 40,000, or at least 50,000 g / mol. The low temperature fraction can have a peak position molecular weight of 250,000 or less, or 200,000 or less, or 150,000 g / mol or less.

[0040] The ethylene / alpha-olefin interpolymer composition may be characterized by a loss tangent (tan δ) at 1 rad / sec of at least 45 or at least 50. The ethylene / alpha-olefin interpolymer may be characterized by a ratio of the loss tangent at 1 rad / sec and 190° C. to the loss tangent at 100 rad / sec and 190° C. of at least 12. These characteristics may be measured by dynamic mechanical spectroscopy (DMS) as described below.

[0041] The ethylene / alpha-olefin interpolymer composition may be characterized by an improved comonomer composition distribution (ICCD) elution profile having at least two distinct peaks between 35°C and 110°C, with a distinct valley (at least 10% drop compared to the peak height of the minor peak) between the peaks, and the peak locations must be at least 10°C apart. Each peak is separated by a vertical line located at the lowest height point of the adjacent valley. The peak temperature of the low temperature peak may be at least 50°C or at least 60°C, and may be less than 90°C or less than 75°C. The peak temperature of the high temperature peak may be at least 90°C, or at least 95°C, and may be less than 110°C, or less than 105°C, or less than 100°C.

[0042] The weight fraction of the low temperature peak fraction may be at least 25 or at least 30 weight percent, and less than 65 weight percent, or less than 60 weight percent, or less than 55 weight percent, based on the total weight of the eluted polymer. The weight fraction of the high temperature peak fraction may be at least 35, or at least 40, or at least 45 weight percent, and less than or equal to 75 weight percent, based on the total weight of the eluted polymer.

[0043] The full width at half maximum of the high temperature peak can be less than 6.0° C. The narrow peak of the high density fraction means a narrower composition distribution without very high or very low molecular weight species that can interfere with spinning performance or produce extractables.

[0044] The ethylene / alpha olefin interpolymer composition may have a composition distribution breadth index (CDBI) of less than 0.5 (i.e., less than 50%), less than 0.3 (30%), less than 0.25 (25%), less than 0.22 (22%), or less than 0.2 (20%).

[0045] The ethylene / alpha-olefin interpolymer composition may have a comonomer distribution constant (CDC) of less than 100, preferably 30-80.

[0046] The ethylene / alpha-olefin interpolymer composition may be characterized by a molecular weighted comonomer distribution index (MWCDI) of greater than 0.20, or greater than 0.25, or greater than 0.30, or greater than 0.35, or greater than 0.40, or greater than 0.45, or greater than 0.50. MWCDI is a measure of the slope of comonomer incorporation as a function of molecular weight obtained from conventional gel permeation chromatography. If the MWCDI is greater than 0.25 (20,000-200,000 g / mol molecular weight range), the resin structure is considered to have significant inverse comonomer incorporation, with more comonomer on the high molecular weight side of the distribution.

[0047] The ethylene / alpha olefin interpolymer compositions may be characterized by low amounts of long chain branching (LCB), which may be indicated by low zero shear viscosity ratios (ZSVR). Specifically, the ZSVR may be less than 1.35 or less than or equal to 1.30. The ZSVR may be at least 1.10.

[0048] The ethylene / alpha-olefin interpolymer composition comprises 1It may be characterized by a vinyl saturation number per 1,000,000 carbon atoms of less than 230, or less than 210, or less than 190, or less than 170, or less than 150, as determined by H-NMR.

[0049] At least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or at least 100% of the second region of the fiber (all percentages are weight percentages based on the total weight of the first region) can be the ethylene / alpha-olefin interpolymer composition. The remaining portion of the second region can be additional components such as one or more other polymers and / or one or more additives. The amount of other polymers can be up to 25%. Possible additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers such as TiO2 or CaCO3, opacifiers, nucleating agents, processing aids, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antimicrobial agents, odor reducing agents, antifungal agents, and combinations thereof. The ethylene / alpha olefin interpolymer composition may contain from about 0.01, or about 0.1, or about 1 percent by total weight of such additives, based on the weight of the ethylene / alpha olefin interpolymer composition including such additives, to about 25, or about 20, or about 15, or about 10 percent.

[0050] Any conventional polymerization process can be used to produce the ethylene / alpha-olefin interpolymer composition. 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 batch reactors, serial batch reactors, and / or any combination thereof. Such conventional polymerization processes also include gas phase, solution or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0051] Generally, solution phase polymerization processes occur in one or more well-mixed reactors, such as one or more isothermal loop reactors or one or more adiabatic reactors, at temperatures in the range of 115-250°C, e.g., 115-200°C, and pressures in the range of 300-1000 psi, e.g., 400-750 psi. In one example, the temperature of the first reactor in a dual reactor is in the range of 115-190°C, e.g., 115-150°C, and the temperature of the second reactor is in the range of 150-200°C, e.g., 170-195°C. In another example, the reactor temperature in a single reactor is in the range of 115-190°C, e.g., 115-150°C. Residence times in solution phase polymerization processes are typically in the range of 2-30 minutes, e.g., 10-20 minutes. Ethylene, solvent, hydrogen, one or more catalyst systems, optionally one or more cocatalysts, and optionally one or more comonomers are continuously fed to one or more reactors. Exemplary solvents include, but are not limited to, isoparaffin. For example, such solvents are commercially available under the name ISOPAR E from ExxonMobil Chemical Co. (Houston, Tex). The resulting mixture of ethylene / alpha-olefin interpolymer and solvent is then removed from the reactor, and the ethylene / alpha-olefin interpolymer composition is isolated. The solvent is typically recovered through a solvent recovery unit, i.e., a heat exchanger and a gas-liquid separator drum, and then recycled to the polymerization system.

[0052] The ethylene / alpha-olefin interpolymer compositions can be produced via solution polymerization in a dual reactor system, such as 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 may be present.

[0053] Ethylene / alpha-olefin interpolymers can be produced through solution polymerization in a single reactor system, such as a single loop reactor system, where ethylene and optionally one or more alpha-olefins are polymerized in the presence of one or more catalyst systems. Two different catalysts can be used in a dual reactor system. One or both of the two different catalysts have formula (I) as shown below. This allows the production of bimodal interpolymer compositions as described above.

[0054] An exemplary catalyst system suitable 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).

[0055] [ka]

[0056] In formula (I), M is a metal selected from titanium, zirconium, or hafnium, the metal is in a formal oxidation state of +2, +3, or +4, n is 0, 1, or 2, when n is 1, X is a monodentate or bidentate ligand, and 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 selected from -O-, -S-, -N(R N )- or -P(R P )-, and L is selected from (C1 to C 40 ) hydrocarbylene or (C1-C 40 ) heterohydrocarbylene, and independently each R N and R P is (C1~C 30 ) hydrocarbyl or (C1-C 30 ) heterohydrocarbyl, (C1-C 40 ) Hydrocarbylene has a moiety containing a linker skeleton of 1 to 10 carbon atoms connecting the two Z groups in formula (I) (to which L is attached), or 40Heterohydrocarbylene has a moiety containing a linker skeleton of 1 to 10 atoms connecting the two Z groups in formula (I), and (C1 to 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 independently, each R C is (C1~C 30 ) hydrocarbyl or (C1-C 30 ) heterohydrocarbyl, R 1 and R 8 are independently -H, (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, -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).

[0057] [ka]

[0058] 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-, R C OC(O)-, R C C(O)N(R N )-, (R N )2NC(O)-, halogen, or -H, where R 1 or R 8 is a radical having the formula (II), formula (III), or formula (IV), where R C、 R N , and R P is as defined above.

[0059] 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, and -H, C , R N , and R P is as defined above.

[0060] The catalyst system comprising the 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, those comprising the metal-ligand complex of formula (I) can be catalytically activated by contacting the complex with an activating cocatalyst or combining the complex with an activating cocatalyst. Activating cocatalysts suitable for use herein include alkylaluminum, 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" means monoalkylaluminum dihydrides or dihalides, dialkylaluminum hydrides or halides, or trialkylaluminum. Examples of polymeric or oligomeric alumoxanes include methylalumoxane, triisobutylaluminum modified methylalumoxane, and isobutylalumoxane.

[0061] The Lewis acid activator (cocatalyst) may be any of the Lewis acid activators having one to three (C1-C 20 Examples of Group 13 metal compounds include tri((C1-C) hydrocarbyl substituents. 20 )hydrocarbyl)-substituted aluminum compounds, or tri((C1-C 20 Additional examples of Group 13 metal compounds include 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. Other examples of Group 13 metal compounds are tris(fluoro-substituted phenyl)borane, tris(pentafluorophenyl)borane. Activating cocatalysts include tris((C1-C 20 )hydrocarbyl)borates (e.g., trityl tetrafluoroborate) or tri((C 1~ 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 ) HydrocarbylN(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.

[0062] As a combination of neutral Lewis acid activators (cocatalysts), tri((C1-C4) alkyl)aluminum and halogenated tri((C6-C 18Examples of suitable neutral Lewis acid mixtures include mixtures containing a mixture of a neutral Lewis acid and a polymeric or oligomeric alumoxane, and a combination of a single neutral Lewis acid, particularly tris(pentafluorophenyl)borane, with a polymeric or oligomeric alumoxane. The molar ratio of (metal-ligand complex):(tris(pentafluorophenylborane):(alumoxane) [e.g., Group 4 metal-ligand complex):(tris(pentafluorophenylborane):(alumoxane)] can be 1:1:1 to 1:10:30, or 1:1:1.5 to 1:5:10.

[0063] Catalyst systems comprising the metal-ligand complexes of formula (I) can be activated to form active catalyst compositions by combining 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.

[0064] One or more of the aforementioned activating cocatalysts may be used in combination with each other. A 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. The 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 an 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 number of moles of tris(pentafluorophenyl)borane to the total number of moles of the one or more metal-ligand complexes of formula (I) that can be used ranges from 0.5:1 to 10:1, 1:1 to 6:1, or 1:1 to 5:1. The remaining activating cocatalysts are generally used in a molar amount approximately equal to the total molar amount of the one or more metal-ligand complexes of formula (I).

[0065] Test Method density Density is measured according to ASTM D792, Method B, in grams / cm 3 (g / cc or g / cm 3 )

[0066] Melt index (I2), (I10), and melt flow rate Melt index (I2) is measured at 190° C., 2.16 kg according to ASTM D-1238. Melt index (I10) is measured at 190° C., 10 kg according to ASTM D1238. Melt flow rate (MFR) is used for polypropylene homopolymer and propylene-ethylene interpolymer and is measured at 230° C., 2.16 kg according to ASTM D-1238. Melt index (I2), (I10), and melt flow rate values ​​are reported in g / 10 min, which corresponds to grams dissolved per 10 minutes.

[0067] Dynamic Mechanical Spectroscopy (DMS) The samples are compression molded into 3 mm thick x 25 mm diameter circular plaques at 177°C for 5 minutes under 10 MPa pressure. The samples are then removed from the press and placed on a counter to cool. Isothermal frequency sweep measurements are performed on the compression molded plaques with an ARES stress controlled rheometer (TA Instruments) equipped with 25 mm parallel plates under a nitrogen purge. The rheometer is allowed to thermally equilibrate for at least 30 minutes before the gap is zeroed for each measurement. The sample disk is placed on the plates and melted at 190°C for 5 minutes. The plates are then closed to a 2 mm gap, the sample is trimmed, and the test is then started. The method may incorporate an additional 5 minute delay to allow the temperature to equilibrate. The experiment is performed at 190°C over a frequency range of 0.1 to 100 rad / sec with 5 points per decade interval. The strain amplitude is constant at 10%. The stress response was analyzed in terms of amplitude and phase from which the storage modulus (G'), loss modulus (G"), complex modulus (G * ), dynamic viscosity (η * ), and the loss tangent (tan δ) (or tan delta). The loss tangent at 1 radian / sec and the loss tangent at 100 radians / sec are obtained.

[0068] Improved Comonomer Composition Distribution (ICCD) The improved comonomer composition distribution (ICCD) test is carried out on a crystallization elution fractionation analyzer (CEF) (PolymerChar, Spain) equipped with an IR-5 detector (PolymerChar, Spain) and a two-angle light scattering detector model 2040 (Precision Detectors, now Agilent Technologies). The ICCD column is 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. The column packing and conditioning were performed in a slurry method according to references (Cong, R.; Parrott, A., Hollis, C., Cheatham, M. International Publication WO 2017040127(A1)). The final pressure with trichlorobenzene (TCB) slurry packing is 150 bar. The column is installed just before the IR-5 detector in the detector oven. Orthodichlorobenzene (ODCB, 99% anhydrous grade or technical grade) is used as the eluent. Silica gel 40 (particle size 0.2-0.5 mm, 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 sparging with dry N2 for 1 h. Sample preparation is performed with the autosampler at 4 mg / mL (unless otherwise stated) with shaking at 160 °C for 1 h. The injection volume is 300 μL. The temperature profile of the ICCD is crystallization from 105 °C to 30 °C at 3 °C / min, followed by thermal equilibration at 30 °C for 2 min (including setting the soluble fraction elution time to 2 min), 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 / sec. Column temperature calibration was performed using 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) / M n(GPC)ICCD temperature calibration can be performed by using a mixture of 101.0°C (having a peak elution temperature of 101.0°C) and eicosane (2 mg / mL). 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 ICCD raw temperature data. Note that this temperature offset is a function of the experimental conditions such as elution temperature, elution flow rate, etc. (3) Creating a linear calibration line that converts the elution temperature over the range of 30.00°C to 140.00°C, such that a linear homopolymer polyethylene standard has a peak temperature at 101.0°C and eicosane has a peak temperature of 30.0°C. (4) For the soluble fraction measured isothermally at 30°C, linearly extrapolating the elution temperatures below 30.0°C by using an elution heating rate of 3°C / min according to references (Cerk and Cong et al., U.S. Pat. No. 9,688,795).

[0069] A calibration line of comonomer content for ICCD (comonomer content in mole percent versus elution temperature (T)) is constructed by using 12 standards with known comonomer content (linear ethylene homopolymers and 11 ethylene-octene random copolymers with weight average molecular weights ranging from 35,000 to 128,000 g / mol made with single-site metallocene catalysts). All of these standards are analyzed in the same manner as specified above at 4 mg / mL. The comonomer content in mole percent and its peak temperature on the elution curve are as follows:

[0070]

number

[0071] Determination of peaks and full width at half maximum on ICCD elution profiles A single baseline is subtracted from the IR measurement signal to create a relative mass-dissolution profile plot that starts and ends 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 T (T)) can be obtained. T (T) vs. T) are from ICCD, from 35.0°C to 119.0°C in temperature step increments of 0.200°C, as follows:

[0072]

number

[0073] w T In a (T) vs. T elution profile, a single peak is defined as a curve with one maximum in the middle and two minimums on either side (lower and higher temperature). The heights of both minimums must be at least 10% lower than the height of the maximum. If one or both minimums have a height less than 10% lower than the height of the maximum, i.e., if one or both minimums have a height greater than 90% of the height of the maximum, then such a curve is considered a shoulder associated with another peak, but not a peak itself. Each individual peak is then divided into two parts by the weighted mean of w T Measure the width in degrees Celsius at 50% of the maximum height of that peak in the (T) vs. T elution profile plot. This width is called the full width at half maximum of the peak.

[0074] If the ICCD elution profile has multiple peaks, the separation point between the peaks (T 分離 The nth peak (WT) can be defined as the lowest point of two adjacent peaks. ピークn The weight fraction of ) can be calculated according to the following formula:

[0075]

number

[0076] The full width at half maximum is defined as the temperature difference between the first intersection of the front temperature and the first intersection of the rear temperature at half the maximum peak height of its respective peak. The front temperature at half the maximum peak is searched forward from 35.0°C, while the rear temperature at half the maximum peak is searched backward from 119.0°C.

[0077] Comonomer Distribution Constant (CDC) The comonomer distribution constant (CDC) is calculated by the ICCD w T (T) vs. T calculated from the elution profile. (1) From ICCD to w in the range of 35.0℃ to 119.0℃ with temperature increase of 0.200℃ T Obtain the (T) vs. T dissolution profile. The total weight fraction from 35 °C to 119 °C should be normalized to 1.0 and follow Equation 2. (2) The median temperature at cumulative weight fraction 0.500 (T 中央値 ) is calculated according to the following formula:

[0078]

number

[0079]

number

[0080]

number

[0081]

number

[0082] Conventional Gel Permeation Chromatography (Conventional GPC) and MWCDI 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 at 160°C and the column compartment was set at 150°C. The columns used were four Agilent "Mixed A" 30 cm, 20 micron linear mixed bed columns. The chromatography solvent used was 1,2,4 trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters and the flow rate was 1.0 milliliters / min.

[0083] Calibration of the GPC column set is performed with 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 at 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. with gentle agitation for 30 minutes. 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)):

[0084]

number

[0085] Use a fifth order polynomial to fit each of the ethylene / alpha-olefin interpolymer equivalent calibration points, such as those obtained for the NIST standard NBS1475 at a molecular weight of 52,000 g / mol, making a small adjustment to A (approximately 0.39-0.44) to correct for column resolution and band broadening effects.

[0086] 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 8) and symmetry (Equation 9) are measured with a 200 microliter injection according to the following formula:

[0087]

number

[0088]

number

[0089] Samples are prepared semi-automatically using PolymerChar "Instrument Control" software to target sample weight of 2 mg / mL and add solvent (containing 200 ppm BHT) via the PolymerChar high temperature autosampler to a pre-nitrogen septa-capped vial. Samples are dissolved at 160°C under "slow" shaking for 3 hours.

[0090] 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 ) and the ethylene / alpha-olefin interpolymer equivalent molecular weight (M in g / mol) obtained from the narrow standard calibration curve for point i from Eq. 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 11a-c. Subsequently, the GPC molecular weight distribution (GPC-MWD) plot (wt GPC (lgMW) vs. lgMW plot (wt GPC (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 10.

[0091]

number

[0092] 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:

[0093]

number

[0094] 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 (nominal)) of each sample by aligning the RV of the respective 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 is then assumed to be related to a linear shift in flow rate (Flow (effective)) throughout the experiment. To facilitate the highest accuracy of the RV measurement of the flow marker peak, a least squares fitting routine is used that fits the peaks of 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 peak, the effective flow rate (with respect to the narrow standard calibration) is calculated as in Equation 12. Processing of the flow marker peaks is performed via the PolymerChar GPCOne™ software. Correct the allowable flow rate so that the effective flow rate is within 0.5% of the nominal flow rate.

[0095]

number

[0096] Calibration of the IR5 detector ratio can be performed using at least eight ethylene / alpha-olefin interpolymer standards (one polyethylene homopolymer and seven ethylene / octene copolymers) of known short chain branching (SCB) frequencies (measured by 13C NMR methods) ranging from homopolymer (0 SCB / 1000 total C) to approximately 50 SCB / 1000 total C (total C=carbons in the backbone+carbons in the branches). Each standard has a weight average molecular weight of 36,000 g / mol to 126,000 g / mol as determined by GPC. Each standard has a molecular weight distribution (M) of 2.0 to 2.5 as determined by GPC. w(GPC) / M n(GPC)) The "IR5 Area Ratio (or "IR5 Methyl Channel Area / IR5 Measurement Channel Area") between the "Baseline Subtracted Area Response of the IR5 Methyl Channel Sensor" and the "Baseline Subtracted Area Response of the IR5 Measurement Channel Sensor" (standard filters and filter wheels supplied by PolymerChar: part number IR5_FWM01 are included as part of the GPC-IR instrument) is calculated for each of the "SCB" standards. A linear approximation of the SCB frequency versus the "IR5 Area Ratio" is constructed in the form of the following equation: SCB / 1000 total C = A0 + [A1 × (IR5 メチルチャネル領域 / IR5 測定チャネル領域 )](Equation 13) (where A0 is the intercept of SCB / 1000 total C at an "IR5 Area Ratio" of zero, and A1 is the slope of SCB / 1000 total C vs. "IR5 Area Ratio", representing the increase in SCB / 1000 total C as a function of "IR5 Area Ratio").

[0097] A series of linear baseline-subtracted chromatographic heights for chromatograms generated by the "IR5 methyl channel sensor" are established as a function of column elution volume to generate a baseline-corrected chromatogram (methyl channel). A series of linear baseline-subtracted chromatographic heights for chromatograms generated by the "IR5 measurement channel" are established as a function of column elution volume to generate a baseline-corrected chromatogram (measurement channel).

[0098] The "IR5 Height Ratio" of the "Baseline Corrected Chromatogram (Methyl Channel)" and the "Baseline Corrected Chromatogram (Measurement Channel)" are calculated at each column elution volume index (each equally spaced index, representing one data point per second at 1 mL / min elution) across the sample integration boundary. The "IR5 Height Ratio" is multiplied by coefficient A1 and coefficient A0 is added to this result to obtain the predicted SCB frequency for the sample. The results are converted to mole percent comonomer as per Equation 14: Mole percent comonomer = {SCB f / [SCBf +((1000-SCB f * length of comonomer / 2)} * 100 (formula 14) (In the formula, “SCB f " is the "SCB per 1000 total C" and "comonomer length" is the number of carbons in the comonomer, e.g., 8 for octene, 6 for hexene, etc.).

[0099] Using the method of Williams and Ward (supra), convert each elution volume index to a molecular weight value (Mwi). Plot "mole percent comonomer" as a function of lg(Mwi) and calculate the slope from an Mwi of 20,000 to an Mwi of 200,000 g / mol (this calculation omits the end group correction for chain ends). Linear regression is used to calculate the slope between and including an Mwi of 20,000 to 200,000 g / mol, in which case the height of the concentration chromatogram (wt GPC The slope of the (lgMW) vs lgMW plot) is at least 10% of the peak height in the chromatogram. This slope is defined as the Molecular Weight Comonomer Distribution Index (MWCDI).

[0100] Zero-shear viscosity ratio (ZSVR) The zero shear viscosity ratio is calculated by the equivalent weight average molecular weight (M w(GPC) ) to the ZSV of a linear polyethylene material (see ANTEC Proceedings below):

[0101]

number

[0102] ZSV value of interpolymer (η 0B is obtained from creep tests at 190°C by the following method: M w(GPC) The ZSV(η) of linear polyethylene is determined by conventional GPC methods (Equation 11b) as described above.0L ) and its M w(GPC) A correlation between ZSV-M and ZSV-M is established based on a series of linear polyethylene reference materials. w(GPC) A discussion of the relationship can be found in the proceedings of ANTEC: Karjala et al., Detection of Low Levels of Long-chain Branching in Polyolefins, Annual Technical Conference-Society of Plastics Engineers (2008), 66th pp. 887-891.

[0103] Creep Test ZSV value of interpolymer (η 0B) are obtained from a constant stress rheometer creep test at 190°C in a nitrogen environment using a DHR (TA Instrument). The samples are subjected to flow between two 25 mm diameter plate fixtures arranged parallel to each other. The samples are prepared by compression molding pellets of the interpolymer into circular plaques of approximately 1.5-2.0 mm thickness. The plaques are further cut into 25 mm diameter disks and sandwiched between the plate fixtures of the TA Instrument. After sample loading, the oven of the TA Instrument is closed for 5 minutes before setting the gap between the plate fixtures to 1.5 mm, opening the oven to trim the edges of the sample, and closing the oven again. Before and after the creep test, a logarithmic frequency sweep of 0.1-100 rad / sec, 300 s soak time, 10% strain at 190°C is performed to determine if the samples have degraded. A constant low shear stress of 20 Pa is applied to all of the samples to ensure that the steady state shear rate is low enough to be in the Newtonian region. Steady state is determined by taking a linear regression on the data in the last 10% time window of the plot of "lg(J(t)) vs. lg(t), where J(t) is creep compliance and t is creep time." If the slope of the linear regression is greater than 0.97, steady state is considered to have been reached and the creep test is then stopped. In all cases in this test, the slope meets the criterion within 1 hour. The steady state shear rate is determined from the slope of the linear regression of all the data points in the last 10% time window of the plot of "ε vs. t, where ε is strain." The zero shear viscosity is determined from the ratio of the applied stress to the steady state shear rate.

[0104] 1 H NMR method To a 0.133 g polymer sample in a 10 mm NMR tube, add 3.26 g of stock solution, which is a mixture of tetrachloroethane-d2 (TCE) and perchloroethylene (50:50 by weight) with 0.001 M Cr 3+ The solution in the tube is mixed with N 2Purge with 500 ml of ethyl acetate for 5 minutes to reduce the amount of oxygen. Leave the capped sample tubes at room temperature overnight to allow the polymer samples to swell. Dissolve the samples at 110°C with periodic vortex mixing. The samples do not contain additives that may contribute to unsaturation, e.g. slip agents such as erucamide. 1 1 H NMR analysis is performed on a Bruker AVANCE 400 MHz spectrometer at 120° C. using a 10 mm cryoprobe.

[0105] Two experiments are performed to measure the degree of unsaturation, one a control and one a double presaturation experiment. In the control experiment, the data are processed with an exponential window function with 1 Hz line broadening and the baseline is corrected to approximately 7 to -2 ppm. The signal from the residual 1H of TCE is set to 100 and the integral value (Itotal) from approximately -0.5 to 3 ppm is used as the signal from the whole polymer in the control experiment. The total carbon number NC in the polymer is calculated with Equation 16 as follows: NC=I 合計 / 2 (formula 16)

[0106] For the double presaturation experiment, the data are processed with an exponential window function with 1 Hz line broadening and the baseline is corrected from approximately 6.6 to 4.5 ppm. 1 The signal from H is set to 100 and the corresponding integral value for unsaturation (I ビニレン , I 三置換 , I ビニル , and I ビニリデン ) is integrated. The use of NMR spectroscopy to determine polyethylenic unsaturation is well known, see for example Busico, V., et al, Macromolecules, 2005, 38, 6988. The number of vinylene, trisubstituted, vinyl, and vinylidene unsaturated units is calculated as follows: N ビニレン =I ビニレン / 2 (Equation 17), N 三置換体 =I 三置換体 (Equation 18), N ビニル =I ビニル / 2 (Equation 19), N ビニリデン =Iビニリデン / 2 (Equation 20).

[0107] The unsaturated units per 1,000 total carbons, i.e., all polymer carbons including the backbone and branches, are calculated as follows: N ビニレン / 1,000C=(N ビニレン / NC)×1,000 (Equation 21), N 三置換体 / 1,000C=(N 三置換体 / NC)×1,000 (Equation 22), N ビニル / 1,000C=(N ビニル / NCH2)×1,000 (Equation 23), N ビニリデン / 1,000C=(N ビニリデン / NC)×1,000 (Equation 24).

[0108] From the residual protons from TCE-d2 1 For H signal, the chemical shift standard is set to 6.0 ppm. The control is performed with ZG pulse, NS=4, DS=12, SWH=10,000 Hz, AQ=1.64 s, D1=14 s. The double presaturation experiment is performed with O1P=1.354 ppm, O2P=0.960 ppm, PL9=57 db, PL21=70 db, NS=100, DS=4, SWH=10,000 Hz, AQ=1.64 s, D1=1 s (D1 is the presaturation time), D13=13 s.

[0109] 13 C NMR method Samples are prepared by adding approximately 3 g of a 50 / 50 mixture of tetrachloroethane-d2 / orthodichlorobenzene containing 0.025 M Cr(AcAc)3 to 0.25 g of polymer sample in a Norell 1001-7 10 mm NMR tube. Oxygen is removed from the sample by purging the tube headspace with nitrogen. The sample is then dissolved and homogenized by heating the tube and its contents to 150°C using a heating block and heat gun. Each sample is visually inspected to ensure homogeneity. Samples are thoroughly mixed immediately prior to analysis and are not allowed to cool before insertion into the heated NMR probe. This is necessary to ensure that the sample is homogenous and representative of the whole. All data are collected using a Bruker 400 MHz spectrometer equipped with a Bruker cryoprobe. Data are acquired using inverse gated decoupling with a 6 second pulse repetition delay, a 90 degree flip angle, and a sample temperature of 120°C. All measurements are performed on non-spinning samples in locked mode. Samples are allowed to thermally equilibrate for 7 minutes prior to data acquisition. 13C NMR chemical shifts are internally referenced to the EEE triad at 30 ppm.

[0110] C13 NMR Comonomer Content: The use of NMR spectroscopy to determine polymer composition is well known. ASTM D 5017-96; JC Randal et al., in "NMR and Macromolecules" ACS Symposium series 247; JC Randal, Ed., Am. Chem. Soc., Washington, DC, 1984, Ch. 9, and JC Randal in "Polymer Sequence Determination", Academic Press, New York (1977) provide general methods for polymer analysis by NMR spectroscopy.

[0111] curvature The amount of curvature is measured via optical microscopy. The amount of curvature is calculated based on the inverse of the radius of the helix formed by the fiber, which is equal to the radius of the circle formed by projecting the helix formed by the fiber onto a surface perpendicular to it. The average of at least five measurements is reported. Measurements are expressed in units of 1 / millimeter (mm -1 ) units.

[0112] Cross-sectional image for measuring center of gravity offset Cross-sectional images of the fibers can be collected using SEM or AFM analysis. For SEM analysis, approximately 10 dyed fibers were mounted in epoxy, cured overnight in the same oven, and polished at low temperature to expose the fibers in cross section. For polishing, a Leica UC7 ultramicrotome was operated at -120 °C and fitted with a diamond knife. The polished fibers were mounted on SEM specimen stubs, coated with iridium sputtered for 25 seconds, and examined with a scanning electron microscope (SEM). An FEI Nova SEM operated at an accelerating voltage of 5 kV, a spot size of 4.5, a #5 objective lens aperture, and a working distance of approximately 12 mm was used, and all images are captured from secondary electron emission using the SEM.

[0113] For AFM analysis, fibers were embedded in epoxy and polished under cryogenic conditions using a Leica UCT / FCS microtome operated at -120 °C for AFM analysis. Topography and phase images were captured at ambient temperature by using a Bruker Icon AFM system equipped with a MikroMasch probe. The probe has a spring constant of 40 N / m, and a resonant frequency of approximately 170 kHz. Imaging frequencies of 0.5 to 2 Hz are used with a set point ratio of approximately 0.8. EXAMPLES

[0114] Preparation of Ethylene / Alpha-Olefin Interpolymer Compositions Prepare development resins ("Resin 1", "Resin 2") according to the process and table below.

[0115] All feedstocks (ethylene monomer and 1-octene comonomer) and process solvents (high purity narrow boiling range isoparaffinic solvent, commercially available from ExxonMobil Chemical under the product name Isopar-E) are purified with molecular sieves prior to introduction into the reaction environment. Hydrogen is supplied under pressure as a high purity grade and is not further purified. The reactor ethylene feed stream is pressurized above the reaction pressure via a mechanical compressor. The solvent and comonomer feeds are pressurized above the reaction pressure via pumps. The individual catalyst components are manually batch diluted with purified solvent to the appropriate component concentrations 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.

[0116] Two reactor systems are used in a series configuration. Each continuous solution polymerization reactor consists of a liquid-filled, non-adiabatic, isothermal circulating loop reactor replicating a continuously stirred tank reactor (CSTR) with heat removal. All fresh solvent, ethylene, hydrogen, and catalyst component feeds can be controlled independently. All fresh feed streams to each reactor (solvent, ethylene, 1-octene, and hydrogen) are temperature controlled to maintain a single solution phase by passing the feed streams through heat exchangers. All fresh feed to each polymerization reactor is injected into the reactor at two points with approximately equal reactor volume between each injection point. Fresh feed is controlled with each injector receiving half of the total fresh feed mass flow rate. Catalyst components are injected into the polymerization reactors through specially designed injection stingers. Primary catalyst (pre-catalyst) component feed is computer controlled to maintain the ethylene conversion of each reactor at a specific target. The cocatalyst components are fed to the primary catalyst (precatalyst) components 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 circulating polymerization reactor with static mixing elements. The contents of each reactor are passed through a heat exchanger that serves to remove most of the heat of reaction and are continuously circulated 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.

[0117] In a dual series reactor configuration, the effluent from the first polymerization reactor (containing solvent, ethylene, 1-octene, hydrogen, catalyst components, and polymer) exits the first reactor loop and is added to the second reactor loop.

[0118] The effluent of the second reactor enters a zone where it is inactivated by addition and reaction with water. Following catalyst inactivation and additive addition, the reactor effluent enters a devolatilization system where the polymer is removed from the non-polymer stream. The isolated polymer melt is pelletized and recovered. The non-polymer stream passes through various equipment that separates most of the ethylene that is removed from the system. The solvent and most of the unreacted 1-octene are recycled back to the reactor after passing through a purification system. A small amount of solvent and 1-octene are purged from the process.

[0119] The examples are prepared using reactor stream feed data flows corresponding to the values ​​in Table 1. The data is presented to allow for the complexity of the solvent recycle system and to allow the reaction system to be more easily treated as a once-through flow diagram. The catalyst components used are referenced in Table 2.

[0120] Each of the polymers made is tested for various properties according to the methods described above.

[0121] [Table 1]

[0122] [Table 2]

[0123] [Table 3]

[0124] In addition to Resin 1 and Resin 2, the following materials are used in the examples.

[0125] Exxon PP 3155, a polypropylene homopolymer having a density of 0.900 g / cc and a melt flow rate of 36 g / 10 min, is commercially available from ExxonMobil Corporation (Irvine, Texas).

[0126] ASPUN™ 6835A, an ethylene / alpha-olefin interpolymer composition having a density of 0.950 g / cc and a melt index (I2) of 17 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Mich.).

[0127] ASPUN™ 6850A, an ethylene / alpha-olefin interpolymer composition having a density of 0.955 g / cc and a melt index (I2) of 30 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Mich.).

[0128] VERSIFY™ 4301, a propylene-ethylene interpolymer having a density of 0.868 g / cc and a melt flow rate of 25 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Michigan).

[0129] VERSIFY™ 4200, a propylene-ethylene interpolymer having a density of 0.876 g / cc and a melt flow rate of 25 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Michigan).

[0130] VERSIFY™ 3200, a propylene-ethylene interpolymer having a density of 0.876 g / cc and a melt flow rate of 8 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Michigan).

[0131] VERSIFY™ 3401, a propylene-ethylene interpolymer having a density of 0.865 g / cc and a melt flow rate of 8 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Michigan).

[0132] DOW™ 10462N, a high density polyethylene homopolymer having a density of 0.963 g / cc and a melt index (I2) of 10 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Mich.).

[0133] DOWLEX™ 2517, an ethylene / alpha-olefin interpolymer composition having a density of 0.917 g / cc and a melt index of 25 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Michigan).

[0134] DOWLEX™ 2027G, a linear low density polyethylene having a density of 0.941 g / cc and a melt index of 4 g / 10 min, is commercially available from The Dow Chemical Company (Midland, Michigan).

[0135] Fiber formation The fibers are spun on a Hills Bicomponent Continuous Filament Fiber Spinning Line. Bicomponent fibers with an eccentric core-sheath configuration are produced. The fibers are spun on a Hills Line according to the following conditions: The extruder profile is adjusted to achieve a melt temperature of 230°C. The throughput rate of each hole is 0.6 ghm (grams per hole per minute). A Hills Bicomponent die is used, operating with a 40 / 60 core / sheath ratio (by weight) with a first zone containing a polymer in one extruder and a second zone containing another polymer in the other extruder according to Table 4 below, to form Comparative Examples (CE) 1, 2, 3, 4, 5, and 6. A Hills Bicomponent die is operated with a core / sheath ratio of 70 / 30 (by weight) with a first zone containing a polymer in one extruder and a second zone containing another polymer in the other extruder according to Table 5 below to form Comparative Examples (CE) 7, 8, 9, 10, 11, and 12 and Inventive Examples (IE) 1, 2, 3, and 4, and 5. The die consists of 144 holes with a hole diameter of 0.6 mm and a length / diameter (L / D) of 4 / 1. The quench air temperature and flow rate are set at 15-18°C and 520 cfm (cubic feet per minute), respectively. After the quenching zone, a drawing tension is applied to the 144 filaments by pneumatically entrapping the filaments in a slot unit in the air stream. The speed of the air stream is controlled by the pressure of the slot aspirator. For each example, four experiments are performed at different pressures, where the slot aspirator pressure is set at 20 psi in one experiment, 30 psi in another, 40 psi in another, and 50 psi in another. For each experiment, the curvature of the fiber of the example is measured. Table 6 below provides the curvature data for the inventive examples and the comparative examples. As can be seen, the inventive examples having a first region to second region weight ratio of 70:30, including a polypropylene blend in the first region and an ethylene / alpha-olefin interpolymer composition in the second region, can show improved curvature compared to the comparative examples. For example, inventive example 3 has a curvature of 3.4 mm at 30 psi. -1, which is significantly higher than any of the comparative examples. Without being bound by any theory, it is believed that the ability of the fiber to have increased curvature results from the weight ratio of the regions and the specific composition of the fiber including the components (e.g., a polypropylene blend including a polypropylene homopolymer and a propylene-ethylene interpolymer, the propylene-ethylene interpolymer having a specific density and melt flow rate, and an ethylene / alpha-olefin interpolymer composition having a specific density and melt index (I2)).

[0136] [Table 4]

[0137] [Table 5]

[0138] [Table 6]

[0139] All documents cited herein, including any cross-referenced or related patents or applications, if any, and any patent applications or patents to which this application claims priority or the benefit thereof, 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 alone, or in any combination with any other reference, teaches, suggests, or discloses such invention. Furthermore, to the extent that a 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.

[0140] 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. It is therefore intended in the appended claims to cover all such changes and modifications that are within the scope of this invention.

Claims

1. A bicomponent fiber, The fiber center of gravity and a first region having a first center of gravity and a second region having a second center of gravity; the first region comprises a polypropylene blend comprising 50 to 90 wt. % of a polypropylene homopolymer, based on the total weight of the polypropylene blend, and 10 to 50 wt. % of a propylene-ethylene interpolymer, based on the total weight of the polypropylene blend, the propylene-ethylene interpolymer having a density of 0.860 to 0.880 g / cc and a melt flow rate of greater than 12 g / 10 min; the second region comprises an ethylene / alpha-olefin interpolymer composition having a density greater than 0.920 g / cc and a melt index (I2) from 10 to 25 g / 10 min; at least one of the first centroid and the second centroid is not the same as the fiber centroid; A bicomponent fiber, wherein the weight ratio of said first regions to said second regions is from 55 / 45 to 90 / 10.

2. the ethylene / alpha-olefin interpolymer composition a density in the range of 0.930 to 0.965 g / cc; The ratio of the weight average molecular weight to the number average molecular weight (M) as determined by GPC is in the range of 1.5 to 2.

6. ｗ（ＧＰＣ） / M ｎ（ＧＰＣ） ) and a molecular weight distribution expressed as a loss tangent at 1 rad / sec of at least 45; a low-temperature peak and a high-temperature peak on the elution profile of the improved comonomer composition distribution (ICCD) from the crystallization elution fraction between 35°C and 110°C; 10. The bicomponent fiber of claim 1, wherein the high temperature peak has a full width at half maximum of less than 6.0°C.

3. 10. The bicomponent fiber of claim 1, wherein the first center of gravity or the second center of gravity is offset from the fiber center of gravity by at least 0.

1.

4. 10. The bicomponent fiber of claim 1, wherein the first region and the second region are arranged in a core-sheath, side-by-side, split-pie, or islands-in-the-sea configuration.

5. At least 1.6 mm －１ The bicomponent fiber of claim 1 having a curvature of

6. 10. The bicomponent fiber of claim 1, further comprising a third region comprising a different polymer than that of the first region and the second region.

7. A nonwoven fabric comprising the bicomponent fiber according to any one of claims 1 to 6.

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