Nonwoven fabric with improved softness

Abstract

A nonwoven fabric comprising a plurality of single-component spunbond fibers containing a polymer material comprising a polymer blend is provided. The nonwoven fabric has: (i) a TS7 value of up to about 30 as determined by a Fabric Softness Analyzer (TSA) from Emtec Innovative Testing Solutions; (ii) an HF value of at least about 40 as determined by a Fabric Softness Analyzer (TSA) from Emtec Innovative Testing Solutions; (iii) a δ value of at least 20, wherein the δ value is determined by subtracting the TS7 value from the HF value; (iv) a TS7 value that is about 5% to about 35% lower than the TS7 value of a nonwoven fabric of the same construction formed from 100% polypropylene; and (v) an HF value that is about 5% to about 35% higher than the HF value of a nonwoven fabric of the same construction formed from 100% polypropylene.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 63 / 219,147, filed July 7, 2021, and U.S. Patent Application No. 63 / 257,209, filed October 19, 2021, pursuant to 35 U.S. SC § 119, each of which is expressly incorporated herein by reference in its entirety. Technical Field

[0003] The embodiments of the currently disclosed invention generally relate to nonwoven fabrics having a plurality of single-component spunbond fibers comprising a polymeric material comprising a polymeric blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one compatibilizer comprising at least one polypropylene-polyethylene copolymer, wherein the nonwoven fabric has improved softness and hand feel. Background Technology

[0004] Various personal hygiene products require soft-touch tops and other materials to provide comfort to users and / or reduce skin irritation associated with prolonged use of such personal hygiene products. Summary of the Invention

[0005] One or more embodiments of the present invention can solve one or more of the above-mentioned problems. According to certain embodiments of the present invention, a nonwoven fabric comprising a plurality of single-component spunbond fibers containing a polymer material comprising a polymer blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one compatibilizer comprising at least one polypropylene-polyethylene copolymer or at least one polypropylene-polyethylene copolymer. The nonwoven fabric may have one or more of the following: (i) a TS7 value of up to about 30 as determined by a Tissue Softness Analyzer (TSA) from Emtec Innovative Testing Solutions; (ii) an HF value of at least about 40 as determined by a Tissue Softness Analyzer (TSA) from Emtec Innovative Testing Solutions; (iii) a δ value of at least 20, wherein the δ value is determined by subtracting the TS7 value from the HF value; (iv) a TS7 value that is about 5% to about 35% lower than the TS7 value of a nonwoven fabric of the same construction formed from 100% polypropylene (e.g., the same polypropylene used in the polymer blend); and (v) an HF value that is about 5% to about 35% higher than the HF value of a nonwoven fabric of the same construction formed from 100% polypropylene (e.g., the same polypropylene used in the polymer blend).

[0006] In another aspect, the present invention provides a method for manufacturing a nonwoven fabric. The method may include: (a) forming a polymer melt comprising a polymer blend of (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one polypropylene-polyethylene copolymer; (b) forming a plurality of single-component spunbond fibers via melt spinning of the polymer melt; and (c) consolidating the plurality of single-component spunbond fibers to form a nonwoven fabric consistent with the nonwoven fabric described and disclosed herein.

[0007] In another aspect, the invention provides articles comprising one or more nonwoven fabrics as described and disclosed herein. These articles may include adult diapers, baby diapers, and pull-up afeminine hygiene pads. According to certain embodiments of the invention, the articles may include a top sheet comprising a nonwoven fabric as described and disclosed herein. Attached Figure Description

[0008] The invention will now be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the invention. In fact, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Throughout the text, the same reference numerals refer to the same elements, and wherein:

[0009] Figure 1 Scatter plots of the softness of various nonwoven fabrics are shown;

[0010] Figure 2 Physical property data of a control sample and a sample according to certain embodiments of the present invention are shown;

[0011] Figure 3A The differential scanning calorimetry (DSC) curves for the control are shown; and

[0012] Figure 3B DSC curves of polymer compositions according to certain embodiments of the present invention are shown. Detailed Implementation

[0013] The invention will now be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the invention. In fact, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in this specification and in the appended claims, the singular form includes the plural reference unless the context clearly indicates otherwise.

[0014] This invention provides a nonwoven fabric comprising a plurality of single-component spunbond fibers containing a polymeric material comprising a polymer blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one compatibilizer comprising at least one polypropylene-polyethylene copolymer or at least one polypropylene-polyethylene copolymer. In this respect, the presence of polyethylene in the polymer blend affects the melting point of the nonwoven web (e.g., unconsolidated single-component fibers) and / or the nonwoven fabric (e.g., consolidated to at least some extent). That is, the presence of polyethylene in the polymer blend lowers the melting and / or softening initiation point of the single-component fibers forming the nonwoven web (e.g., unconsolidated single-component fibers) and / or the nonwoven fabric (e.g., consolidated nonwoven fabric that can be bonded to individual nonwoven layers or individual membrane layers). Therefore, the nonwoven web formed from single-component spunbond fibers can be thermally bonded at a reduced temperature (e.g., ultrasonic bonding, hot rolling, etc.), which provides energy savings and good tensile properties at lower bonding temperatures. Furthermore, when attempting to laminate with lower melt structures such as polyethylene films, the reduced melt temperature onset (e.g., the initiation of softening and / or melting at a lower temperature) provides valuable benefits, allowing for lower processing energy and fewer opportunities for film damage / void at the bonding point.

[0015] Furthermore, when used in spunbond-meltblown-spunbond (SMS) nonwoven fabrics, a lower melting temperature initiation point is further advantageous. This is due to the suppression of the melting point of the spunbond layer, or the individual layers such as those described and disclosed herein. When implementing an SMS construction, if the melting point of the spunbond fibers is similar to that of the meltblown fibers, they generally tend to bond under optimal tensile conditions, which can damage the smaller diameter meltblown fibers because they have a smaller mass, resulting in "pinholes" and a lower barometric head value regarding barrier performance. According to certain embodiments of the invention, by lowering the initiation point of the spunbond fiber's melting point, the desired tensile strength in the bonding curve can be achieved, while maintaining a point below the physical "pinhole" point of the meltblown structure. In this respect, certain embodiments of the invention can both improve tensile strength and maintain the barometric head value. Furthermore, the reduction in the melting initiation point of spunbond monocomponent fibers can also be valuable in porosity measurements, for example, due to the maximum reduction in pore size caused by the prevention of pinholes that may occur in meltblown structures.

[0016] According to certain embodiments of the present invention, nonwoven fabrics can be provided as components of composite structures (e.g., SMS-type nonwoven fabrics or nonwoven-film composites).

[0017] The terms “basically” or “substantially” according to certain embodiments of the invention may cover the entire amount as specified, or according to other embodiments of the invention may cover most but not all of the specified amount (e.g., 95%, 96%, 97%, 98%, or 99% of the specified total amount).

[0018] As used interchangeably herein, the term "polymer" or "of a polymer" may include: homopolymers; copolymers, such as block copolymers, graft copolymers, random copolymers, and alternating copolymers; terpolymers; etc.; and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term "polymer" or "of a polymer" shall include all possible structural isomers of such polymers or polymeric materials; stereoisomers, including but not limited to geometric isomers, optical isomers, or enantiomers; and / or any chiral molecular configuration. These configurations include, but are not limited to, isotactic, syndiotactic, and atactic configurations of such polymers or polymeric materials. The term "polymer" or "of a polymer" shall also include polymers made from various catalyst systems, including but not limited to Ziegler-Natta catalyst systems and metallocene / unit point catalyst systems. According to certain embodiments of the invention, the term "polymer" or "of a polymer" shall also include polymers produced by fermentation processes or of biological origin.

[0019] As used herein, the terms "nonwoven fabric" and "nonwoven web" can include a web having a structure of interlaid, but not interwoven in a recognizable repeating manner, individual fibers, filaments, and / or threads. According to certain embodiments of the invention, nonwoven fabrics or nonwoven webs can be formed by any method conventionally known in the art, such as meltblowing, spunbonding, needle punching, hydroentangling, air-laid, and a combination of carding and web-forming. As used herein, a "nonwoven web" can comprise a plurality of individual fibers that have not undergone a consolidation process.

[0020] As used herein, the terms “fabric” and “nonwoven fabric” can include a web in which a plurality of fibers are mechanically entangled or interconnected, fused together and / or chemically bonded. For example, a nonwoven web of individually webped fibers can be subjected to a bonding or consolidation process to bond at least a portion of the individual fibers together to form a coherent (e.g., cohesive) web of interconnected fibers.

[0021] As used herein, the terms "consolidated" and "consolidated" can include bringing together at least a portion of the fibers of a nonwoven web to achieve closer proximity or attachment between them (e.g., thermally fused together, chemically bonded together, and / or mechanically entangled together) to form one or more bonding points, which are used to increase resistance to external forces (e.g., abrasive and tensile forces) relative to an unconsolidated web. One or more bonding points may, for example, include discrete or localized regions in the web material that have been softened or melted and optionally subsequently or simultaneously compressed to form discrete or localized deformations in the web material. Furthermore, the term "consolidated" can include an entire nonwoven web that has been processed to bring together at least a portion of the fibers to achieve closer proximity or attachment between them (e.g., thermally fused together, chemically bonded together, and / or mechanically entangled together), as just a few examples, such as by thermal bonding or mechanical entanglement (e.g., hydroentangling). According to certain embodiments of the invention, such a web may be considered a "consolidated nonwoven," a "nonwoven fabric," or simply a "fabric."

[0022] As used herein, the term "short fiber" can include cut fibers derived from filaments. According to certain embodiments, any type of filament material can be used to form short fibers. For example, short fibers can be formed from polymer fibers and / or elastic fibers. Non-limiting examples of materials may include polyolefins (e.g., polypropylene or polypropylene-containing copolymers), polyethylene terephthalate, and polyamides. By way of example only, the average length of short fibers can be from about 2 cm to about 15 cm.

[0023] As used herein, the term "spunbond" can include fibers formed by extruding molten thermoplastic material as filaments from a plurality of fine, generally circular capillaries of a spinneret, with the diameter of the extruded filaments then rapidly decreasing. According to one embodiment of the invention, as disclosed and described herein, spunbond fibers are generally not viscous when deposited onto a collection surface and are generally continuous. Note that the spunbonds used in certain composite materials of the invention can include those described in the literature. Nonwoven fabrics. Spunbond fibers may include, for example, continuous fibers.

[0024] As used herein, the term "continuous fiber" refers to a fiber that has not been cut from its original length before being formed into a nonwoven web or nonwoven fabric. The average length of a continuous fiber can range from more than about 15 centimeters to more than one meter, and up to the length of the web or fabric formed. For example, as used herein, a continuous fiber can include fibers in which the length of the fiber is at least 1,000 times the average diameter of the fiber, such as at least about 5,000, 10,000, 50,000, or 100,000 times the average diameter of the fiber.

[0025] As used herein, according to certain embodiments of the invention, the term "meltblown" can include fibers formed by extruding molten thermoplastic material as melt lines or filaments through a plurality of fine die capillaries into a converging, high-velocity, typically hot, gas (e.g., air) stream, which thins the molten thermoplastic material filaments to reduce their diameter, which can be down to the diameter of a microfiber. According to one embodiment of the invention, the die capillaries can be circular. Subsequently, the meltblown fibers are carried by a high-speed gas flow and deposited on a collection surface to form a web of randomly distributed meltblown fibers. The meltblown fibers can include microfibers that can be continuous or discontinuous and are generally viscous when deposited on the collection surface. However, the length of meltblown fibers is shorter than that of spunbond fibers.

[0026] As used herein, the term “layer” can include generally identifiable combinations of similar material types and / or functions present in the XY plane.

[0027] As used herein, the term "multicomponent fiber" can include fibers formed from at least two (e.g., two or more) different polymeric materials that are extruded from separate extruders but spun together to form a single fiber. As used herein, the term "bicomponent fiber" can include fibers formed from two different polymeric materials that are extruded from separate extruders but spun together to form a single fiber. The polymeric materials or polymers are arranged in substantially constant positions in different regions throughout the cross-section of the multicomponent fiber and extend continuously along the length of the multicomponent fiber. Such multicomponent fibers can be constructed, for example, in a sheath / core arrangement where one polymer is surrounded by the other, or in a side-by-side arrangement, a disc arrangement, or an "island-in-the-sea" arrangement, each of which is known in the field of multicomponent fibers (including bicomponent fibers).

[0028] As used herein, the term "single-component fiber" can include fibers formed from a single polymer or polymer blend (e.g., a blend or mixture of two or more polymers) extruded from a single extruder. A single polymer or polymer blend may, for example, define a polymer matrix in which one or more additives (e.g., fillers) may be dispersed.

[0029] As used herein, the term "machine orientation" or "MD" includes the direction in which the fabric is produced or conveyed. As used herein, the term "transverse orientation" or "CD" includes the direction of the fabric that is substantially perpendicular to the MD.

[0030] As used herein, the term "aspect ratio" refers to the ratio of the length of the major axis to the length of the minor axis of the cross section of the fiber under discussion.

[0031] All integer endpoints disclosed herein that can generate smaller ranges within the given range disclosed herein are within the scope of certain embodiments of the invention. As an example, disclosures of about 10 to about 15 include, for example, disclosures with intermediate ranges such as: about 10 to about 11; about 10 to about 12; about 13 to about 15; about 14 to about 15; and so on. Furthermore, all single decimal endpoints (e.g., reported to the nearest tenth) that can generate smaller ranges within the given range disclosed herein are within the scope of certain embodiments of the invention. As an example, disclosures of about 1.5 to about 2.0 include, for example, disclosures with intermediate ranges such as: about 1.5 to about 1.6; about 1.5 to about 1.7; about 1.7 to about 1.8; and so on.

[0032] In one aspect, the present invention provides a nonwoven fabric comprising a plurality of single-component spunbond fibers containing a polymeric material comprising a polymeric blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one compatibilizer comprising at least one polypropylene-polyethylene copolymer or at least one polypropylene-polyethylene copolymer. The nonwoven fabric may have one or more of the following: (i) a TS7 value of up to about 30 as determined by a fabric softness analyzer (TSA) from Emtec Innovative Testing Solutions; (ii) an HF value of at least about 40 as determined by a fabric softness analyzer (TSA) from Emtec Innovative Testing Solutions; (iii) a δ value of at least 20, wherein the δ value is determined by subtracting the TS7 value from the HF value; (iv) a TS7 value that is about 5% to about 35% lower than the TS7 value of a nonwoven fabric (e.g., the same area weight, the same bonding pattern, the same bonding area, etc.) formed from 100% polypropylene (e.g., the same polypropylene used in the polymer blend); and (v) an HF value that is about 5% to about 35% higher than the HF value of a nonwoven fabric (e.g., the same area weight, the same bonding pattern, the same bonding area, etc.) formed from 100% polypropylene (e.g., the same polypropylene used in the polymer blend). The softness values ​​determined by TSA include “TS7” data, which is a direct measurement of the sample’s softness (e.g., via blade vibration caused by fiber stiffness measured by a TSA device). The “HF” value is a composite value based on “TS7”, “TS750”, and “D” data. The “HF” value provides an objective assessment of the overall feel of the sample. The “TS750” data is a direct measurement of the sample’s roughness (e.g., via vertical vibration from the sample caused by horizontal blade movement across the sample surface measured by a TSA device). The “D” data is the sample stiffness directly measured by a TSA device due to sample deformation under a defined force.

[0033] According to certain embodiments of the invention, the TS7 value of the nonwoven fabric is from about 2 to about 50, for example at least about any of the following: 2, 3, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24 and 25, and / or at most about any of the following: 50, 45, 40, 35, 30, 29, 28, 27, 26 and 25. Additionally or alternatively, the HF value of the nonwoven fabric is from about 40 to about 120, for example at least about any of the following: 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 65 and 70, and / or at most about any of the following: 120, 115, 110, 105, 100, 95, 90, 85, 80, 75 and 70. Alternatively or concurrently, the δ value of the nonwoven fabric is from about 20 to about 75, for example, at least about any of the following: 20, 22, 24, 26, 28, 30, 32, 34 and 35, and / or at most about any of the following: 75, 70, 65, 60, 55, 50, 45, 44, 42, 40, 38, 36 and 35.

[0034] According to certain embodiments of the invention, the TS7 value of the nonwoven fabric is about 5% to about 35% lower than that of a similarly constructed nonwoven fabric (e.g., same area weight, same bonding pattern, same bonding area, etc.) formed from 100% polypropylene (e.g., the same polypropylene used in polymer blends), for example, at least about any of the following: 5%, 6%, 8%, 10%, 12%, 14%, and 15%, and / or at most about 35%, 30%, 25%, 24%, 22%, 20%, 18%, 16%, and 15%. In this respect, as demonstrated by the reduced / lower TS7 value, the TS7 value of the nonwoven fabric has increased softness relative to a similarly constructed nonwoven fabric (e.g., same area weight, same bonding pattern, same bonding area, etc.) formed from 100% polypropylene (e.g., the same polypropylene used in polymer blends). By way of example only, the TS7 value of a nonwoven fabric according to certain embodiments of the invention may be 24, while the TS7 value of a nonwoven fabric of the same construction formed from 100% polypropylene (e.g., the same polypropylene used in the polymer blend) may be 31 (e.g., the TS7 value of a nonwoven fabric according to certain embodiments of the invention is about 29% lower).

[0035] According to certain embodiments of the invention, the HF value of the nonwoven fabric is about 5% to about 35% higher than that of a similarly constructed nonwoven fabric formed from 100% polypropylene (e.g., the same polypropylene used in polymer blends), for example, at least about any of the following: 5%, 6%, 8%, 10%, 12%, 14%, and 15%, and / or up to about 35%, 30%, 25%, 24%, 22%, 20%, 18%, 16%, and 15%. In this respect, as demonstrated by the increased / larger HF value, the HF value of the nonwoven fabric has an enhanced overall hand feel relative to a similarly constructed nonwoven fabric formed from 100% polypropylene (e.g., the same polypropylene used in polymer blends). By way of example only, the HF value of a nonwoven fabric according to certain embodiments of the invention may be 60, while the HF value of a similarly constructed nonwoven fabric formed from 100% polypropylene (e.g., the same polypropylene used in a polymer blend) may be 46 (e.g., the HF value of a nonwoven fabric according to certain embodiments of the invention is about 27% higher).

[0036] According to certain embodiments of the invention, the polymer blend may comprise about 60% to about 90% by weight of at least one polypropylene polymer, for example, at least about any of the following: 60% by weight, 62% by weight, 64% by weight, 65% by weight, 66% by weight, 68% by weight, 70% by weight, 72% by weight, 74% by weight, 77% by weight, 78% by weight, and 80% by weight, and / or at most about any of the following: 90% by weight, 88% by weight, 86% by weight, 85% by weight, 84% by weight, 83% by weight, 82% by weight, 81% by weight, and 80% by weight. At least one polypropylene polymer may, for example, be a first polypropylene polymer (e.g., a single polypropylene polymer).

[0037] According to certain embodiments of the present invention, the melt flow rate (MFR) of at least one polypropylene polymer, as determined according to ASTM D1238 (230°C / 2.16 kg), can be from about 10 g / 10 min to about 100 g / 10 min, for example, at least about any of the following: 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 16 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 25 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 32 g / 10 min, 34 g / 10 min, 35 g / 10 min, 36 g / 10 min, 38 g / 10 min, etc. 10 minutes, 40g / 10 minutes, 42g / 10 minutes, 44g / 10 minutes, 45g / 10 minutes, 46g / 10 minutes, 48g / 10 minutes and 50g / 10 minutes, and / or at most about any of the following: 100g / 10 minutes, 95g / 10 minutes, 90g / 10 minutes, 85g / 10 minutes, 80g / 10 minutes, 75g / 10 minutes, 70g / 10 minutes, 65g / 10 minutes, 60g / 10 minutes, 58g / 10 minutes, 56g / 10 minutes, 55g / 10 minutes, 54g / 10 minutes, 52g / 10 minutes and 50g / 10 minutes.

[0038] According to certain embodiments of the invention, the polymer blend may comprise from about 5 wt% to about 30 wt% of at least one polyethylene polymer, for example, at least about any of the following: 5 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, and 15 wt%, and / or at most about any of the following: 30 wt%, 28 wt%, 26 wt%, 25 wt%, 24 wt%, 22 wt%, 20 wt%, 18 wt%, 16 wt%, and 15 wt%. At least one polyethylene polymer may, for example, be a first polyethylene polymer (e.g., a single polyethylene polymer).

[0039] According to certain embodiments of the invention, the melt flow rate (MFR) of at least one polyethylene polymer, as determined according to ASTM D1238 (190°C / 2.16 kg), can be from about 1 g / 10 min to about 30 g / 10 min, for example at least about any of the following: 1 g / 10 min, 2 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 14 g / 10 min and 15 g / 10 min, and / or at most about any of the following: 30 g / 10 min, 25 g / 10 min, 20 g / 10 min, 18 g / 10 min, 16 g / 10 min and 15 g / 10 min.

[0040] According to certain embodiments of the invention, the polymer blend may comprise from about 1 wt% to about 10 wt% of at least one polypropylene-polyethylene copolymer, for example, at least about any of the following: 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%, and / or at most about any of the following: 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, and 5 wt%. At least one polypropylene-polyethylene copolymer may, for example, be a first polypropylene-polyethylene copolymer (e.g., a single polypropylene-polyethylene copolymer).

[0041] The first polypropylene-polyethylene copolymer may include a first block copolymer or a first random copolymer. According to certain embodiments of the invention, the first polypropylene-polyethylene copolymer is an EP-iPP diblock polymer.

[0042] According to certain embodiments of the invention, the ethylene monomer content of the first polypropylene-polyethylene copolymer may be from about 5% to about 60% by weight, for example at least about any of the following: 5%, 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 26%, 38%, 40%, 42%, 44%, and 45% by weight, and / or at most about any of the following: 60%, 58%, 56%, 55%, 54%, 52%, 50%, 48%, 46%, and 45% by weight. Alternatively or concurrently, the melt flow rate (MFR) of at least one polypropylene-polyethylene copolymer (e.g., the first polypropylene-polyethylene copolymer) as determined according to ASTM D1238 (230°C / 2.16 kg) may be from about 0.5 g / 10 min to about 20 g / 10 min, for example according to ASTM D1238. D1238 (230℃ / 2.16kg) specifies at least approximately any one of the following: 0.5g / 10min, 1g / 10min, 1.5g / 10min, 2g / 10min, 2.5g / 10min, 3g / 10min, 3.5g / 10min, 4g / 10min, 4.5g / 10min, 5g / 10min, 5.5g / 10min, 6g / 10min, 6.5g / 10min, 7g / 10min, 7.5g / 10min, 8g / 10min, 8.5g / 10min, 9g / 10min, 9.5g / 10min, and 10g / 10min, and / or according to ASTM. D1238 (230℃ / 2.16kg) was determined to be at most about any of the following: 20g / 10min, 19g / 10min, 18g / 10min, 17g / 10min, 16g / 10min, 15g / 10min, 14g / 10min, 13g / 10min, 12g / 10min, 11g / 10min, and 10g / 10min.

[0043] Recent advances in single-site catalysts (e.g., metallocene catalysts) have enabled the production of a variety of polymer structures that are difficult or impossible to produce economically. In this regard, first polypropylene-polyethylene copolymers may include copolymers formed by single-site catalysts, such as metallocene-catalyzed copolymers. For example, polypropylene-based polymers with significant amounts of ethylene content can be produced in a variety of configurations (e.g., well-defined blocks) to further enhance the copolymer's ability to bridge generally immiscible polymers. Examples of such materials include the polypropylene-based elastomer Vistamaxx containing copolymers of propylene and ethylene. TM (For example, Vistamaxx) TM6202). These propylene-based elastomers, for example, comprise isotactic stereopolypropylene microcrystalline regions and random amorphous regions (e.g., ethylene). Such olefin copolymers can comprise hard blocks and soft blocks, wherein the hard blocks are predominantly propylene and the soft blocks are predominantly ethylene. In this respect, the hard blocks (e.g., propylene) can account for 10% to 90% by weight of the copolymer, while the soft blocks can account for 90% to 10% by weight of the copolymer. In this respect, these copolymers contain a random ethylene distribution throughout the copolymer. Vistamaxx TM (For example, Vistamaxx) TM The 6202 copolymer is commercially available from ExxonMobil. Vistamaxx TM 6202 has a density of 0.862 g / cc, an MI of 9.1 (190°C / 2.16 kg), an MFR of 20 (230°C / 2.16 kg load), and an ethylene content of 15% by weight. Further examples include olefin diblock copolymers, which comprise EP-iPP diblock polymers such as Intune, which are polypropylene-based block copolymers containing ethylene monomers. TM According to certain embodiments of the invention, the first polypropylene-polyethylene copolymer disclosed herein can be prepared, for example, by contacting an addition-polymerizable monomer or mixture of monomers with a composition comprising at least one addition polymerization catalyst, a co-catalyst, and a chain shuttling agent (“CSA”) under addition polymerization conditions, wherein the method is characterized in that at least some growing polymer chains are formed under different process conditions in two or more regions of two or more reactors operating under steady-state polymerization conditions or in two or more regions of a reactor operating under plug flow polymerization conditions. According to certain embodiments of the invention, the first polypropylene-polyethylene copolymer may comprise an olefin block copolymer formed by a single-point catalyst or other catalyst system. That is, according to certain embodiments of the invention, the first polypropylene-polyethylene copolymer may not be produced by a single-point catalyst. According to certain embodiments of the invention, the first polypropylene-polyethylene copolymer has no anhydride functionality, such as maleic anhydride functionality.

[0044] According to certain embodiments of the invention, copolymers formed by a single-point catalyst as discussed above can be distinguished from conventional random copolymers, physical blends of polymers, and block copolymers prepared via sequential monomer addition. These copolymers can be distinguished from random copolymers by characteristics such as a higher melting temperature of a comparable amount of comonomer and a block complexation index, as described below; from physical blends by characteristics such as a block complexation index, better tensile strength, improved breaking strength, finer morphology, improved optical properties, and greater impact strength at lower temperatures; and from block copolymers prepared via sequential monomer addition by molecular weight distribution, rheology, shear thinning, and rheological ratio, and by the presence of block polydispersity.

[0045] As another example, the first polypropylene-polyethylene copolymer may include an EP-iPP diblock polymer, wherein the ethylene content of the EP-iPP diblock polymer is 43% to 48% by weight, or 43.5% to 47% by weight, or 44% to 47% by weight, based on the weight of the diblock copolymer. In an exemplary embodiment, the propylene content of the EP-iPP diblock polymer may be 57% to 52% by weight, or 56.5% to 53% by weight, or 56% to 53% by weight, based on the weight of the EP-iPP diblock polymer.

[0046] According to certain embodiments of the invention, the first MFR ratio between at least one polypropylene polymer of the polymer blend, as determined according to ASTM D1238 (230°C / 2.16kg), and the second MFR of at least one polyethylene polymer, as determined according to ASTM D1238 (230°C / 2.16kg), is about 5:1 to about 20:1, for example, at least about any of the following: 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, and 12:1, and / or at most about any of the following: 20:1, 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, and 12:1.

[0047] According to certain embodiments of the invention, the MFR of the polymer blend, as determined by ASTM D1238 (230°C / 2.16kg), is about 20 g / 10 min to about 60 g / 10 min, for example, at least about any of the following, as determined by ASTM D1238 (230°C / 2.16kg): 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 25 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 32 g / 10 min, 34 g / 10 min, 35 g / 10 min, 36 g / 10 min, 38 g / 10 min, and 40 g / 10 min, and / or according to ASTM D1238 (230°C / 2.16kg). D1238 (230℃ / 2.16kg) was determined to be at most approximately any of the following: 60g / 10min, 59g / 10min, 58g / 10min, 56g / 10min, 55g / 10min, 54g / 10min, 52g / 10min, 50g / 10min, 49g / 10min, 48g / 10min, 47g / 10min, 46g / 10min, 45g / 10min, 44g / 10min, 43g / 10min, 42g / 10min, 41g / 10min, and 40g / 10min.

[0048] According to certain embodiments of the invention, the average diameter of the plurality of single-component spunbond fibers is from about 10 micrometers to about 30 micrometers, for example at least about any of the following: 10 micrometers, 12 micrometers, 14 micrometers, 15 micrometers, 16 micrometers, 18 micrometers and 20 micrometers, and / or at most about any of the following: 30 micrometers, 28 micrometers, 26 micrometers, 25 micrometers, 24 micrometers, 22 micrometers and 20 micrometers.

[0049] According to certain embodiments of the present invention, the polymer material may further comprise a compatibilizer containing anhydride functionality, such as a maleic anhydride polymer or a maleic anhydride-modified polymer. Additionally or alternatively, the polymer material may also comprise one or more fillers, such as one or more organic fillers and / or one or more inorganic fillers (e.g., calcium carbonate particles, pigments, etc.). According to certain embodiments of the present invention, the polymer material may also comprise one or more slip agents, such as amides. One or more slip agents may include, for example, primary amides, secondary amides, tertiary amides, diamides, or any combination thereof. According to certain embodiments of the present invention, one or more slip agents may include one or more primary amides. As an example, primary amides suitable as slip agents according to certain embodiments of the present invention may include erucamide, oleamide, stearamide, behenamide, or any combination thereof. Alternatively or additionally, certain embodiments of the present invention may comprise one or more slip agents, wherein the one or more slip agents include one or more secondary amides. As an example, secondary amides suitable as slip agents according to certain embodiments of the present invention include oleyl palmitamide, stearyl erucamide, or any combination thereof. Alternatively or additionally, certain embodiments of the present invention may comprise one or more slip agents, said slip agents including one or more bisamides such as ethylenebisamide. As an example, suitable bisamides as slip agents according to certain embodiments of the present invention include ethylenebisstearamide, ethylenebisoleamide, or any combination thereof. According to certain embodiments of the present invention, the slip agent may comprise an amide (e.g., primary amide, secondary amide, tertiary amide, bisamide, etc.) containing one or more saturated or unsaturated aliphatic chains. According to certain embodiments of the present invention, one or more aliphatic chains may each independently contain about 1 to about 30 carbon atoms (e.g., about 5 to about 30 carbon atoms). For example, secondary amides and bisamides may comprise two saturated and / or unsaturated carbon chains that may each independently contain about 1 to about 30 carbon atoms (e.g., about 5 to about 30 carbon atoms). By way of example only, one or more aliphatic chains may each independently contain at least about any of the following: 1, 5, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 carbon atoms and / or up to about 30, 29, 28, 27, 26, 25, 20, and 15 carbon atoms (e.g., about 15 to about 25 carbon atoms, about 20 to 30 carbon atoms, etc.). According to certain embodiments of the invention, the lubricant may comprise an amide comprising an unsaturated aliphatic chain having one or more elements or degrees of unsaturation. An element of unsaturation corresponds to two fewer hydrogen atoms than in a saturated formula. For example, a single double bond constitutes one element of unsaturation, while a triple bond would constitute two elements of unsaturation.According to certain embodiments of the invention, the lubricant comprises an unsaturated aliphatic chain containing about 1 to about 10 elements with unsaturation (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 elements with saturation).

[0050] According to certain embodiments of the invention, a plurality of single-component spunbond fibers comprise circular cross-sections, non-circular cross-sections, or both. For example, non-circular cross-section fibers may comprise a disc-shaped cross-section, a multi-leaf-shaped cross-section, or a ribbon-shaped cross-section. According to certain embodiments of the invention, a plurality of single-component spunbond fibers comprise non-circular cross-sections with an aspect ratio of at least about 1.5:1, for example, about 1.5:1 to about 10:1.

[0051] According to certain embodiments of the invention, a plurality of single-component spunbond fibers define a first nonwoven layer, and the nonwoven fabric further includes one or more additional nonwoven layers, such as at least a second nonwoven layer. In this respect, the nonwoven fabric may comprise a multilayer nonwoven fabric. The one or more additional layers may, for example, comprise a spunbond layer, a meltblown layer, a carded layer, a hydroentangled layer, a cellulose layer, or any combination thereof. According to certain embodiments of the invention, the nonwoven fabric includes one or more cellulose layers located directly or indirectly between the first nonwoven layer and the second nonwoven layer, wherein the second nonwoven layer comprises a second spunbond layer or a spunbond-meltblown-spunbond layer.

[0052] For example, nonwoven fabrics, such as SMS-type nonwoven fabrics, can be provided as components of the composite structure. In this respect, a plurality of monocomponent spunbond fibers can define a first spunbond nonwoven layer of the SMS structure, wherein each "S" can include about 1 to about 5 spunbond layers and each "M" can include about 1 to about 5 meltblown layers. According to certain embodiments of the invention, a second plurality of monocomponent spunbond fibers can define a second spunbond nonwoven layer of the SMS structure. In this respect, each of the outermost spunbond layers can be formed from monocomponent spunbond fibers as described and disclosed herein. According to certain embodiments of the invention, the melt initiation point of the spunbond layers, such as those described and disclosed herein, is at least about 3°C ​​lower than the second melt initiation point of the meltblown layers, for example, at least about 3°C, 5°C, 6°C, 8°C, and 10°C, and / or at most about any of the following: 40°C, 35°C, 30°C, 25°C, 20°C, 18°C, 15°C, 12°C, and 10°C. In other words, the difference between the melting initiation point of the spunbond layer and the second melting initiation point of the meltblown layer can be at least about 3°C, for example, at least about 3°C, 5°C, 6°C, 8°C and 10°C, and / or at most about any of the following: 40°C, 35°C, 30°C, 25°C, 20°C, 18°C, 15°C, 12°C and 10°C, wherein the melting initiation point of the spunbond layer is lower than the second melting initiation point of the meltblown layer.

[0053] According to certain embodiments of the invention, the present invention provides an SMS structure in which one or both of the outermost spunbond nonwoven layers are formed of polymeric materials and / or polymer blends as described and disclosed herein. For example, the SMS structure may include a first spunbond layer, at least one meltblown layer, and at least a second spunbond layer, with the at least one meltblown layer located between the first and second spunbond layers. The first spunbond layer comprises a plurality of monocomponent spunbond fibers and defines a first outermost spunbond nonwoven layer of the SMS structure. According to certain embodiments of the invention, the second spunbond layer comprises a second plurality of monocomponent spunbond fibers and defines a second outermost spunbond nonwoven layer of the SMS structure, wherein the second plurality of monocomponent spunbond fibers are formed of the same polymeric material or polymer blend as the first spunbond layer. For example, each of the outermost spunbond nonwoven layers may be formed of polymeric materials and / or polymeric compositions as described and disclosed herein.

[0054] According to certain embodiments of the invention, at least one meltblown layer may comprise a plurality of meltblown fibers containing a meltblown polymer composition comprising 50% to 100% by weight of one or more polypropylenes and / or polypropylene having a vis-breaker, for example at least about any of the following by weight: 50%, 60%, 70%, 80% and 90%, and / or at most about any of the following by weight: 100%, 99%, 98%, 96%, 95%, 94%, 92% and 90%. Alternatively or concurrently, the melt flow rate of the meltblown polymer composition, as defined in ASTM D1238 (230°C / 2.16kg), may be from about 500 g / 10 min to about 2000 g / 10 min, for example, at least about any one of the following as defined in ASTM D1238 (230°C / 2.16kg): 500 g / 10 min, 600 g / 10 min, 700 g / 10 min, 800 g / 10 min, 900 g / 10 min, 1000 g / 10 min, 1100 g / 10 min, and 1200 g / 10 min, and / or as defined in ASTM D1238 (230°C / 2.16kg). The D1238 (230℃ / 2.16kg) is determined to be at most about any of the following: 2000g / 10min, 1900g / 10min, 1800g / 10min, 1600g / 10min, 1500g / 10min, 1400g / 10min and 1200g / 10min.

[0055] According to certain embodiments of the invention, the nonwoven fabric can be thermally solidified at a temperature lower than the melting initiation point of the aforementioned meltblown polymer composition, depending on the difference in melting point initiation points between the spunbond nonwoven layer and at least one meltblown layer. For example, the lower melting initiation point of the spunbond nonwoven layer provides solidification of the SMS structure at a temperature sufficient to bond the individual layers together to form an SMS structure, without creating pores (e.g., pinholes) in the meltblown layer. According to certain embodiments of the invention, the plurality of meltblown fibers are not softened or melted during the thermal bonding operation. According to certain embodiments of the invention, at least one meltblown layer is free of pinholes. In this respect, the invention also provides a method for forming an SMS structure, wherein the SMS structure is solidified at a temperature lower than the softening and / or melting initiation point of the plurality of meltblown fibers. Due to the reduced optimal bonding temperature of the spunbond nonwoven layer, thus preventing the formation of pinholes in the meltblown layer (e.g., compared to a 100% PP spunbond nonwoven layer), the resulting SMS structure can provide both high tensile strength and high water head.

[0056] In addition, nonwoven fabrics can be provided as components of composite structures (e.g., nonwoven-film composites). For example, nonwoven fabrics can be directly bonded to polymeric films, such as polyethylene films. Polymeric films can comprise monolayers or multilayers (e.g., a core layer sandwiched between two surface layers). Additionally or alternatively, polymeric films can comprise microporous films and / or monolithic films (e.g., films without pores or substantially without pores). According to certain embodiments of the invention, the melt initiation point of the spunbond layer, such as those described and disclosed herein, is at least about 3°C ​​lower than the third melt initiation point of the polymeric film layer, for example, at least about 3°C, 5°C, 6°C, 8°C, and 10°C, and / or at most about any of the following: 40°C, 35°C, 30°C, 25°C, 20°C, 18°C, 15°C, 12°C, and 10°C. In other words, the difference between the melting initiation point of the spunbond layer and the third melting initiation point of the polymer film layer can be at least about 3°C, for example, at least about 3°C, 5°C, 6°C, 8°C and 10°C, and / or at most about any of the following: 40°C, 35°C, 30°C, 25°C, 20°C, 18°C, 15°C, 12°C and 10°C, wherein the melting initiation point of the spunbond layer is lower than the third melting initiation point of the polymer film layer.

[0057] According to certain embodiments of the invention, the nonwoven fabric has a surface weight of at least about 2 grams per square meter (gsm), for example, at least about any of the following: 2 gsm, 4 gsm, 5 gsm, 6 gsm, 8 gsm, 10 gsm, 12 gsm, 14 gsm, 15 gsm, 16 gsm, 18 gsm, 20 gsm, 22 gsm, 25 gsm, 28 gsm, 30 gsm. m, 32gsm, 35gsm, 38gsm, 40gsm, 42gsm, 45gsm, 48gsm, 50gsm, 52gsm, 55gsm, 58gsm and 60gsm, and / or at most about any one of the following: 100gsm, 95gsm, 90gsm, 85gsm, 80gsm, 75gsm, 70gsm, 65gsm and 60gsm.

[0058] In another aspect, the present invention provides a method for manufacturing nonwoven fabrics, such as those described and disclosed herein. The method may include: (a) forming a polymer melt comprising a polymer blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one compatibilizer comprising at least one polypropylene-polyethylene copolymer or consisting of at least one polypropylene-polyethylene copolymer; (b) forming a plurality of single-component spunbond fibers via melt spinning of the polymer melt; and (c) consolidating the plurality of single-component spunbond fibers to form a nonwoven fabric consistent with the nonwoven fabrics described and disclosed herein.

[0059] According to certain embodiments of the present invention, the step of forming a polymer melt includes: selecting at least one polypropylene polymer, at least one polyethylene polymer, and at least one compatibilizer and blending them at an elevated temperature, wherein at the elevated temperature (e.g., 230°C), the MFR of the at least one polyethylene polymer is less than the MFR of the at least one polypropylene polymer, and the difference between the MFR of the at least one polypropylene polymer and the MFR of the at least one polyethylene polymer is less than about 35. For example, the difference between the MFR of the at least one polypropylene polymer and the MFR of the at least one polyethylene polymer can be from about 1 to about 35, for example, at least about any of the following: 1, 3, 5, 8, 10, 12, 15, 18, and 20, and / or at most about any of the following: 35, 32, 20, 28, 26, 25, 24, 22, and 20. According to certain embodiments of the invention, the elevated temperature includes about 190°C to about 250°C, for example, at least about any of the following: 190°C, 200°C, 210°C, and 215°C, and / or at most about any of the following: 250°C, 245°C, 240°C, 235°C, 230°C, 225°C, 220°C, and 215°C. According to certain embodiments of the invention, the polymer blend can be extruded and / or melt-spun at one or more of the aforementioned elevated temperatures. According to certain embodiments of the invention, the polymer blend can be extruded and melt-spun at the same elevated temperature.

[0060] According to certain embodiments of the invention, the step of consolidating a plurality of single-component spunbond fibers may include a thermal bonding operation, an ultrasonic bonding operation, a mechanical bonding operation, an adhesive bonding operation, or any combination thereof. The consolidation step may, for example, include forming a plurality of individual bonding points by a thermal bonding operation or an ultrasonic operation. In this respect, the plurality of individual bonding points define a bonded area. The bonded area may, for example, comprise from about 3% to about 30% of the nonwoven fabric, for example at least about any of the following: 3%, 4%, 5%, 6%, 8%, 10%, 12%, 14%, and 15%, and / or at most about any of the following: 30%, 28%, 26%, 25%, 24%, 22%, 20%, 18%, 16%, and 15%. Alternatively or concurrently, the step of forming a plurality of individual bonding points may be carried out at a temperature of about 120°C to about 150°C, for example at least about any of the following: 120°C, 122°C, 124°C, 125°C, 126°C, 128°C, 130°C, 132°C, 134°C and 135°C, and / or at most about any of the following: 150°C, 148°C, 146°C, 145°C, 144°C, 142°C, 140°C, 138°C, 136°C and 135°C.

[0061] In another aspect, the invention provides articles comprising one or more nonwoven fabrics as described and disclosed herein. These articles may include adult diapers, baby diapers, and pull-up feminine hygiene pads. According to certain embodiments of the invention, the articles may include a top sheet comprising a nonwoven fabric as described and disclosed herein.

[0062] Example

[0063] The present disclosure is further illustrated by the following examples, which should not be construed as limiting. That is, the specific features described in the following examples are merely exemplary and not limiting. For each of the tensile strength and percentage elongation measurements, the WSP 110.4 (Newtons / 5cm) Edana-type method (50mm strip tensile test) was performed.

[0064] (I)

[0065] Four separate samples were prepared, at least in part based on the polymer composition from which the samples were formed, to bond the samples at their optimal bonding temperature. Each of the samples was subjected to the same bonding mode. Each of the samples was subjected to various tests to evaluate certain physical properties and softness properties.

[0066] Comparison:

[0067] A first nonwoven fabric (i.e., PP3155E5 from Exxon) is formed from 100% by weight of polypropylene homopolymer with an MFR of 36 g / 10 min according to ASTM D1238 (230°C / 2.16 kg). Figure 1 (PP control - 140C). The nonwoven fabric was hot-stitched at 140°C.

[0068] Example #1

[0069] A second nonwoven fabric formed from the following polymer composition as a single-component fiber (i.e., Figure 1 Example #1): (i) 80% by weight of a polypropylene homopolymer with an MFR of 36 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., PP3155E5 from Exxon); (ii) 15% by weight of a linear low-density polyethylene with an MFR of 2.5 g / 10 min according to ASTM D1238 (190°C / 2.16 kg) (i.e., PE-Dowlex 2036.01G from Dow); and (iii) 5% by weight of an EP-iPP diblock polymer with an MFR of 9.5 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., Intune). TM-Dow D5545). The nonwoven fabric was hot-stitched at a temperature of 135°C.

[0070] Comparative Example #1

[0071] A third nonwoven fabric formed from the following polymer composition as a single-component fiber (i.e., Figure 1 Comparative Example #1): (i) 93.5% by weight of polypropylene homopolymer with an MFR of 36 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., PP3155E5 from Exxon); (ii) 5% by weight of Vistamaxx with an MFR of 9.1 g / 10 min according to ASTM D1238 (230°C / 2.16 kg). TM 6202FL, which is a polypropylene-based elastomer comprising a random copolymer of propylene and ethylene; and (iii) 1.5% by weight of erucamide. The nonwoven fabric was hot-stitched at a temperature of 140°C.

[0072] Comparative Example #2

[0073] The fourth nonwoven fabric of polypropylene-polyethylene bicomponent fibers (i.e., Figure 1 Comparative Example #2) has a sheath / core structure, wherein the sheath is formed of polyethylene and the core is formed of the aforementioned polypropylene homopolymer (i.e., PP3155E5 from Exxon). The polyethylene is ASPUN from Dow. TM 6850A. The nonwoven fabric was hot-stitched at a temperature of 130°C.

[0074] Figure 1 A summary of softness data determined using a TSA-Fabric Softness Analyzer from Emtec Innovative Testing Solutions is provided. In this context, “TS7” data represents a direct measurement of the sample’s softness (e.g., by measuring blade vibration due to fiber stiffness via a TSA device), and “HF” values ​​are composite values ​​based on “TS7”, “TS750”, and “D” data. The “HF” value provides an objective assessment of the overall feel of the sample. “TS750” data represents a direct measurement of the sample’s roughness (e.g., by measuring vertical vibration from the sample due to horizontal blade movement across the sample surface via a TSA device). “D” data represents the sample stiffness directly measured by a TSA device due to sample deformation under a defined force.

[0075] like Figure 1As shown, Example 1 has the lowest "TS7" value, which, as mentioned above, is a direct measurement of the sample's softness. Additionally, Example 1 has the highest HF value, which, as mentioned above, is an objective assessment of the sample's overall feel. In this respect, Example 1 is superior to each of the comparative examples and the control sample.

[0076] (II)

[0077] Various nonwoven fabrics were formed from the above polymer composition. Physical properties and softness data were collected for each sample. The results are summarized in Table 1 below.

[0078]

[0079] Table 1

[0080] '1' indicates a sample manufactured according to the 'control' from section (I) above;

[0081] '2' indicates a sample manufactured according to 'Comparative Example #2' from Part (I) above, under the conditions of the binding temperature shown in Table 1;

[0082] '3' indicates a sample manufactured according to 'Example #1' from Part (I) above, under the conditions of the binding temperature shown in Table 1;

[0083] '4' indicates a sample manufactured according to 'Comparative Example #1' from Part (I) above, under the conditions of the binding temperature shown in Table 1;

[0084] (III)

[0085] Three separate samples were prepared and subjected to the same bonding mode. Each sample was subjected to multiple tests to evaluate softness properties (summarized in Table 2) and certain physical properties (summarized in Table 3 and shown below). Figure 2 (In the middle). As discussed above, determine the softness properties “HF”, “TS7”, and “D” values. Test the coefficient of friction (CoF) using an IMASSSP2000 instrument according to ASTM D1894.

[0086] Comparison:

[0087] A first nonwoven fabric (i.e., control PP Mono in Tables 2 and 3) was formed from 100% by weight of polypropylene homopolymer (i.e., PP3155E5 from Exxon) with an MFR of 36 g / 10 min according to ASTM D1238 (230°C / 2.16 kg). This nonwoven fabric was then hot-stitched at 137°C.

[0088] like Figure 3A As shown above, a polypropylene homopolymer used to form a control was subjected to differential scanning calorimetry (DSC). Figure 3A As shown, the DSC curve includes a single peak 10 with a melting initiation point of approximately 147°C.

[0089] Example 1

[0090] The second nonwoven fabric (i.e., PP / PE / Intune in Tables 2 and 3) is formed from the following polymer compositions: (i) 80% by weight of polypropylene homopolymer with an MFR of 36 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., PP3155E5 from Exxon); (ii) 15% by weight of linear low-density polyethylene with an MFR of 2.5 g / 10 min according to ASTM D1238 (190°C / 2.16 kg) (i.e., PE-Dowlex2036.01G from Dow); and (iii) 5% by weight of EP-iPP diblock polymer with an MFR of 9.5 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., Intune). TM -Dow D5545). The nonwoven fabric was hot-stitched at a temperature of 130°C.

[0091] like Figure 3B As shown above, the polymer composition used to form the single-component fibers of Example 1 was subjected to differential scanning calorimetry (DSC). Figure 3B As shown, the DSC curve includes two prominent peaks. For example, the DSC curve includes a first peak 20 representing the melting of the polyethylene component and a second peak 30 associated with the polypropylene component. The melting initiation point of the first peak 20 is approximately 124°C. In this respect, the polymer composition of Example 1 provides a significantly reduced melting initiation point, which allows for the utilization of a reduced calendering temperature (e.g., a reduced bonding temperature) while still providing good tensile properties as shown in Table 3. This has been verified by... Figure 3A The dashed line 23 on the DSC curve overlaps with the approximate melt initiation point of the polymer composition of Example 1 to help illustrate the reduction of the melt initiation point.

[0092] Example 2

[0093] A third nonwoven fabric (i.e., PP / PE / Intune / NHP01 in Tables 2 and 3) is formed from the following polymer composition to form a single-component fiber: (A) the following polymer blends: (i) 80% by weight of a polypropylene homopolymer with an MFR of 36 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., PP3155E5 from Exxon), (ii) 15% by weight of a linear low-density polyethylene with an MFR of 2.5 g / 10 min according to ASTM D1238 (190°C / 2.16 kg) (i.e., PE-Dowlex 2036.01G from Dow), and (iii) 5% by weight of an EP-iPP diblock polymer with an MFR of 9.5 g / 10 min according to ASTM D1238 (230°C / 2.16 kg) (i.e., Intune). TM (B) 1.5% erucamide by weight of the polymer composition. The nonwoven fabric was hot-stitched at 130°C.

[0094]

[0095] Table 2;

[0096]

[0097] Table 3

[0098] As shown in Table 3 and Figure 2 As shown, nonwoven fabrics formed from polymer blends according to certain embodiments of the present invention provide similar to or even improved tensile strength while bonding at lower temperatures.

[0099] These and other modifications and variations to the invention can be practiced by those skilled in the art without departing from the spirit and scope of the invention (which is more specifically set forth in the appended claims). Furthermore, it should be understood that aspects of the various embodiments can be interchanged, in whole or in part. Moreover, those skilled in the art will understand that the foregoing description is merely illustrative and is not intended to limit the invention as further described in such appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the exemplary descriptions of the various variations contained herein.

Claims

1. A nonwoven fabric comprising: A plurality of single-component spunbond fibers containing a polymer material comprising a polymer blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer, and (iii) at least one compatibilizer comprising at least one first polypropylene-polyethylene copolymer or at least one first polypropylene-polyethylene copolymer, wherein the first polypropylene-polyethylene copolymer is a first block copolymer or a first EP-iPP diblock polymer and the melt flow rate (MFR) of the first polypropylene-polyethylene copolymer as determined by ASTM D1238 at 230°C and 2.16 kg is 0.5 g / 10 min to 20 g / 10 min; The nonwoven fabric described herein has one or more of the following: (i) a TS7 value of up to 30 as determined by a fabric softness analyzer (TSA) from Emtec Innovative Testing Solutions; (ii) an HF value of at least 40 as determined by a fabric softness analyzer (TSA) from Emtec Innovative Testing Solutions; (iii) a δ value of at least 20, wherein the δ value is determined by subtracting the TS7 value from the HF value; (iv) a TS7 value that is 5% to 35% lower than the TS7 value of a nonwoven fabric of the same construction formed from 100% polypropylene; and (v) an HF value that is 5% to 35% higher than the HF value of a nonwoven fabric of the same construction formed from 100% polypropylene.

2. The nonwoven fabric according to claim 1, wherein the nonwoven fabric has one or more of the following: (i) a TS7 value of 2 to 30; (ii) an HF value of 40 to 120; (iii) a δ value of 20 to 75; or (iv) any combination thereof.

3. The nonwoven fabric according to claim 2, wherein the TS7 value is at least any one of the following: 3, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24 and 25.

4. The nonwoven fabric according to claim 2, wherein the TS7 value is at most any one of the following: 29, 28, 27, 26 and 25.

5. The nonwoven fabric according to claim 2, wherein the HF value is at least any one of the following: 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 65 and 70.

6. The nonwoven fabric according to claim 2, wherein the HF value is at most any one of the following: 115, 110, 105, 100, 95, 90, 85, 80, 75 and 70.

7. The nonwoven fabric according to claim 2, wherein the δ value is at least any one of the following: 22, 24, 26, 28, 30, 32, 34 and 35.

8. The nonwoven fabric according to claim 2, wherein the δ value is at most any one of the following: 70, 65, 60, 55, 50, 45, 44, 42, 40, 38, 36 and 35.

9. The nonwoven fabric according to claim 1 or 2, wherein the polymer blend comprises: (a) 60% to 90% by weight of the at least one polypropylene polymer, (b) 5% to 30% by weight of the at least one polyethylene polymer, and (c) 1% to 10% by weight of the at least one polypropylene-polyethylene copolymer.

10. The nonwoven fabric according to claim 9, wherein the polymer blend comprises: (a) at least one of the following polypropylene polymers: 62 wt%, 64 wt%, 65 wt%, 66 wt%, 68 wt%, 70 wt%, 72 wt%, 74 wt%, 77 wt%, 78 wt%, and 80 wt%.

11. The nonwoven fabric according to claim 9, wherein the polymer blend comprises: (a) at least one polypropylene polymer of at most any of the following: 88 wt%, 86 wt%, 85 wt%, 84 wt%, 83 wt%, 82 wt%, 81 wt%, and 80 wt%.

12. The nonwoven fabric of claim 9, wherein the polymer blend comprises: (b) at least one of the following polyethylene polymers: 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, and 15 wt%.

13. The nonwoven fabric according to claim 9, wherein the polymer blend comprises: (b) at least one polyethylene polymer of at most any of the following: 28 wt%, 26 wt%, 25 wt%, 24 wt%, 22 wt%, 20 wt%, 18 wt%, 16 wt%, and 15 wt%.

14. The nonwoven fabric of claim 9, wherein the polymer blend comprises: (c) at least one of the following polypropylene-polyethylene copolymers: 2% by weight, 3% by weight, 4% by weight and 5% by weight.

15. The nonwoven fabric according to claim 9, wherein the polymer blend comprises: (c) at least one of the following polypropylene-polyethylene copolymers: 9 wt%, 8 wt%, 7 wt%, 6 wt%, and 5 wt%.

16. The nonwoven fabric according to claim 1 or 2, wherein the first polypropylene-polyethylene copolymer has: (i) an ethylene monomer content of 5% to 60% by weight.

17. The nonwoven fabric according to claim 16, wherein the first polypropylene-polyethylene copolymer has: (i) at least any of the following: 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 26%, 38%, 40%, 42%, 44%, and 45% ethylene monomer content by weight.

18. The nonwoven fabric according to claim 16, wherein the first polypropylene-polyethylene copolymer has: (i) at most any one of the following: 58%, 56%, 55%, 54%, 52%, 50%, 48%, 46% and 45% ethylene monomer content by weight.

19. The nonwoven fabric according to claim 1 or 2, wherein the MFR ratio between the first MFR of the at least one polypropylene polymer determined according to ASTM D1238 at 230°C and 2.16 kg and the second MFR of the at least one polyethylene polymer determined according to ASTM D1238 at 230°C and 2.16 kg is 5:1 to 20:

1.

20. The nonwoven fabric of claim 19, wherein the MFR ratio is at least any one of the following: 6:1, 7:1, 8:1, 9:1, 10:1, 11:1 and 12:

1.

21. The nonwoven fabric of claim 19, wherein the MFR ratio is at most any one of the following: 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1 and 12:

1.

22. The nonwoven fabric according to claim 1 or 2, wherein the polymer material further comprises one or more fillers; and / or one or more slip agents, wherein the one or more slip agents comprise one or more amides.

23. The nonwoven fabric of claim 22, wherein the polymer material further comprises one or more organic fillers and / or one or more inorganic fillers.

24. The nonwoven fabric according to claim 22, wherein the one or more slip agents comprise erucamide, oleamide, stearamide, betaine amide, oleopalmitoamide, stearo-erucamide, ethylene bis-stearamide, ethylene bis-oleamide, or any combination thereof.

25. The nonwoven fabric of claim 1 or 2, wherein the plurality of single-component spunbond fibers define a first nonwoven layer, and wherein the nonwoven fabric further comprises one or more additional nonwoven layers, the one or more additional nonwoven layers comprising at least a second nonwoven layer.

26. The nonwoven fabric of claim 25, wherein the one or more additional layers comprise a spunbond layer, a meltblown layer, a carded layer, a hydroentangled layer, a cellulose layer, or any combination thereof.

27. The nonwoven fabric of claim 26, wherein the nonwoven fabric comprises an SMS structure, the SMS structure comprising a first spunbond layer, at least one meltblown layer and at least a second spunbond layer, the at least one meltblown layer being located between the first spunbond layer and the second spunbond layer; wherein the first spunbond layer comprises the plurality of monocomponent spunbond fibers and defines a first outermost spunbond nonwoven layer of the SMS structure.

28. The nonwoven fabric of claim 27, wherein the second spunbond layer comprises a second plurality of single-component spunbond fibers and defines a second outermost spunbond nonwoven layer of the SMS structure; wherein the second plurality of single-component spunbond fibers are formed of the same polymer material or polymer blend as the first spunbond layer.

29. The nonwoven fabric of claim 1, wherein the polymer material comprises one or more slip agents, and the one or more slip agents comprise one or more amides.

30. The nonwoven fabric according to claim 29, wherein the one or more slip agents include erucamide, oleamide, stearamide, betaine amide, oleopalmitamide, stearo-erucamide, ethylene bis-stearamide, ethylene bis-oleamide, or any combination thereof.

31. A method for manufacturing a nonwoven fabric, comprising: (a) Forming a polymer melt comprising a polymer blend of: (i) at least one polypropylene polymer, (ii) at least one polyethylene polymer and (iii) at least one polypropylene-polyethylene copolymer, wherein the at least one polyethylene polymer and the at least one first polypropylene-polyethylene copolymer are different; (b) Forming a plurality of single-component spunbond fibers by melt spinning the polymer melt; (c) Consolidate the plurality of single-component spunbond fibers to form a nonwoven fabric according to any one of claims 1 to 30.

32. The method of claim 31, wherein the step of forming the polymer melt comprises selecting the at least one polypropylene polymer, the at least one polyethylene polymer, and at least one compatibilizer and blending the at least one polypropylene polymer, the at least one polyethylene polymer, and the at least one compatibilizer at an elevated temperature, wherein, as determined according to ASTM D1238 at 230°C and 2.16 kg, the melt flow rate (MFR) of the at least one polyethylene polymer at the elevated temperature is less than the MFR of the at least one polypropylene polymer, and the difference between the MFR of the at least one polypropylene polymer and the MFR of the at least one polyethylene polymer is less than 35 g / 10 min.

33. The method according to claim 31 or 32, wherein consolidating the plurality of single-component spunbond fibers comprises forming a plurality of individual bonding points by thermal bonding or ultrasonic bonding, and wherein the formation of the plurality of individual bonding points is carried out at a temperature of 120°C to 150°C.

34. The method of claim 33, wherein the formation of the plurality of individual bonding points is carried out at a temperature of at least any one of the following: 122°C, 124°C, 125°C, 126°C, 128°C, 130°C, 132°C, 134°C, and 135°C.

35. The method of claim 33, wherein the formation of the plurality of individual bonding points is carried out at a temperature of at most any one of the following: 148°C, 146°C, 145°C, 144°C, 142°C, 140°C, 138°C, 136°C, and 135°C.

36. An article comprising: A top sheet comprising a nonwoven fabric according to any one of claims 1 to 30, wherein the article comprises adult diapers, baby diapers, and pull-up feminine hygiene pads.

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