Method of bonding and heat setting nonwoven web

Abstract

A method for forming a nonwoven fabric is provided. The method includes depositing at least a first nonwoven layer comprising a first plurality of interwoven individual melt spun fibers, the first plurality of interwoven individual melt spun fibers may include a plurality of monocomponent fibers having different melt initiation temperatures, bicomponent fibers having different fiber components having different melt initiation temperatures, and / or a plurality of different bicomponent fibers having one or more different components having different melt initiation temperatures. The method includes subjecting a precursor nonwoven web to a heat setting operation (HSO) to heat set a first plurality of intermediate independent melt spun fibers to form an intermediate nonwoven fabric, and then consolidating the intermediate nonwoven fabric to provide the nonwoven fabric.

Description

[0001] Cross-references to related applications Pursuant to 35 USC §119(e), this application claims priority to U.S. Patent Application No. 63 / 466,032, filed May 12, 2023, the entire disclosure of which is expressly incorporated herein by reference. Technical Field

[0002] The embodiments of the currently disclosed invention generally relate to a method for forming a nonwoven fabric, wherein the method includes subjecting a nonwoven fiber web to a heat-setting operation while physically constraining the nonwoven fiber web to reduce or prevent shrinkage or relative movement between individual melt-spun fibers, thereby “heat-setting” the nonwoven fiber web, and then consolidating it to form a nonwoven fabric. Background Technology

[0003] In nonwoven fabrics, bicomponent fibers can be used, wherein one component of the bicomponent fiber, such as the sheath component of a sheath / core configuration, can be formed from a low-melting-point polymer composition, while the other component is formed from a different polymer composition with a higher melting point. In this respect, the component of the bicomponent fiber formed from the low-melting-point polymer composition can be used for consolidation while maintaining the structural integrity of the component of the bicomponent fiber formed from the polymer composition with the higher melting point. Alternatively, the nonwoven fabric can be formed from a mixture of fibers formed from different polymer materials, for example, a first set of fibers formed from a low-melting-point polymer composition and a second set of fibers formed from a high-melting-point polymer composition. However, each of these methods requires the use of multiple polymer compositions and multiple polymer flow paths from their respective polymer sources to their respective spinneret capillaries.

[0004] Alternatively, as described in co-owned and co-pending application 63 / 427,584 filed November 23, 2022, which was converted into co-owned and co-pending application 18 / 514,141 filed November 20, 2023, discloses a method that utilizes a specific spinneret melt-spinning polymer composition (e.g., a single polymer composition) to provide a nonwoven fabric comprising lower melting point fibers and higher melting point fibers that optionally remain solidified during consolidation. 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 method for forming a nonwoven fabric is provided, comprising the step of directly or indirectly depositing at least a first nonwoven layer comprising a first plurality of interwoven individual melt-spun fibers onto a moving collection belt to provide a precursor nonwoven fiber web having an average initial transverse (CD) width and / or an average initial basis weight. The first plurality of interwoven individual melt-spun fibers may comprise (a) a combination of a first group of monocomponent fibers and a second group of monocomponent fibers, the first group of monocomponent fibers having a first melt initiation temperature and the second group of monocomponent fibers having a second melt initiation temperature below the first melt initiation temperature; (b) a bicomponent fiber comprising a first component and a second component, the first component having a first melt initiation temperature and the second component having a second melt initiation temperature below the first melt initiation temperature; (c) a combination of a first group of bicomponent fibers and a second group of bicomponent fibers, the first group of bicomponent fibers having a first higher melting point component and a first lower melting point component, the second group of bicomponent fibers having a second higher melting point component and a second lower melting point component that begins to melt before the first lower melting point component; or (d): any combination of (a)-(c). The method may further include conveying a precursor nonwoven fiber web through a heat-setting operation (HSO), the heat-setting operation comprising (a) directly or indirectly constraining the precursor nonwoven fiber web within a heat-setting roller gap defined between a moving collection belt and a portion of an opposing surface, such as a portion of a heat-setting device, to mitigate relative movement of individually melt-spun fibers during HSO, and (b) subjecting the precursor nonwoven fiber web to a high temperature sufficient to increase the viscosity of a second component of the second set of monocomponent fibers and / or bicomponent fibers having a second melt initiation temperature, to provide a second lower melting point component of the intermediate nonwoven fabric and / or the second set of bicomponent fibers. The method may further include removing the intermediate nonwoven fabric from the HSO, wherein the intermediate nonwoven fabric has an average post-heat-setting CD width and / or an average post-heat-setting basis weight, and consolidating the intermediate nonwoven fabric to provide a nonwoven fabric having an average final CD width and / or an average final basis weight. According to certain embodiments of the invention, HSO may lightly bond or consolidate a portion of the melt-spun fibers together to provide sufficient integrity for processing, while the consolidation step bonds the melt-spun fibers together more thoroughly to provide a final nonwoven fabric that is significantly more durable and stronger than the intermediate nonwoven fabric formed after HSO.

[0006] In another aspect, the present invention provides a heat-set nonwoven fabric comprising at least a first plurality of interwoven individual melt-spun fibers, the first plurality of interwoven individual melt-spun fibers comprising (a) a combination of a first group of monocomponent fibers and a second group of monocomponent fibers, the first group of monocomponent fibers having a first melt initiation temperature and the second group of monocomponent fibers having a second melt initiation temperature lower than the first melt initiation temperature; (b) a bicomponent fiber comprising a first component and a second component, the first component having a first melt initiation temperature and the second component having a second melt initiation temperature lower than the first melt initiation temperature; (c) a combination of a first group of bicomponent fibers and a second group of bicomponent fibers, the first group of bicomponent fibers having a first higher melting point component and a first lower melting point component, the second group of bicomponent fibers having a second higher melting point component and a second lower melting point component that begins to melt before the first lower melting point component; or (d): any combination of (a)-(c). The nonwoven fabric may be a through-air-bonded nonwoven fabric, a chemically bonded nonwoven fabric, a mechanically bonded nonwoven fabric, and / or a thermally bonded nonwoven fabric. In this regard, nonwoven fiber webs (e.g., spunbond fiber webs) can be consolidated by a through-fluid bonding method (e.g., the fluid including hot air or steam), wherein optionally, only lower melting point fibers (or components) are softened, melted, and / or flowed through a portion of the nonwoven fiber web to form an adhesive with the higher melting point fibers. In this respect, according to certain embodiments of the invention, the structural integrity of the resulting nonwoven fabric can be provided by the higher melting point fibers (or higher melting point fiber components), which can remain in an undeformed or substantially undeformed state (e.g., the cross-section of the high melting point fibers or fiber components remains the same or substantially the same before, during, and after the consolidation operation). Conversely, low melting point fibers (or fiber components) may have a deformed cross-section or be individually indistinguishable as individual fibers due to melting and / or flow to provide an adhesive mechanism for consolidation. For example, low melting point fibers (or fiber components) may at least partially melt and flow through at least some of the gaps defined between the high melting point fibers. As low-melting-point fibers (or fiber components) flow through the gaps between high-melting-point fibers, deformed and flowing low-melting-point fibers (e.g., less crystalline or amorphous) coat the surface of the high-melting-point fibers (or fiber components). After coating the surface of the higher-melting-point fibers (or fiber components), as the lower-melting-point material (e.g., molten and flowing lower-melting-point fibers) solidifies, the lower-melting-point material forms an adhesion with the higher-melting-point material (e.g., deformed lower-melting-point fibers) and an adhesion between the higher-melting-point materials.

[0007] In another aspect, the present invention provides a method for forming a composite material, comprising forming or providing a nonwoven fabric, such as those described and disclosed herein, and bonding a membrane layer to the nonwoven fabric. In yet another aspect, the present invention provides a composite material comprising a nonwoven fabric, such as those described and disclosed herein, and a membrane. Attached Figure Description

[0008] Various embodiments of the invention will now be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, of the embodiments of the invention. In fact, these inventions 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 to enable this disclosure to meet applicable legal requirements. The same numerals always denote the same elements, and wherein: Figure 1 A schematic diagram illustrating a general method according to certain embodiments of the present invention; Figure 2 A schematic diagram illustrating another general method according to certain embodiments of the present invention is shown; Figure 3 A schematic diagram illustrating another general method according to certain embodiments of the present invention is shown; Figure 4 A schematic diagram illustrating another general method according to certain embodiments of the present invention is shown; Figure 5 Nonwoven fabrics according to certain embodiments of the present invention include a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers). Figure 6 The nonwoven fabric shown according to certain embodiments of the present invention includes a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining two high-melting-point regions and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a low-melting-point region. Figure 7 The nonwoven fabric shown according to certain embodiments of the present invention includes a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining an internal high-melting-point region and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining two low-melting-point regions. Figure 8A nonwoven fabric according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions, wherein the high-melting-point regions and the low-melting-point regions are positioned alternately along the z-direction; Figure 9 Another nonwoven fabric according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions, wherein the high-melting-point regions and the low-melting-point regions are positioned alternately along the z-direction; Figure 10 A nonwoven fabric according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions, wherein the high-melting-point regions and the low-melting-point regions are positioned laterally in an alternating manner; Figure 11 A nonwoven fabric according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions, wherein the high-melting-point regions and the low-melting-point regions are positioned alternately along the z-direction and laterally; Figure 12 A nonwoven fabric according to certain embodiments of the invention is shown, having a second set of melt-spun fibers (e.g., a second set of monocomponent melt-spun fibers and / or a second set of bicomponent fibers) defining a continuous low-melting-point region and a first set of melt-spun fibers (e.g., a first set of monocomponent melt-spun fibers and / or a first set of bicomponent fibers) defining a plurality of high-melting-point regions dispersed throughout the low-melting-point region; and Figure 13 The nonwoven fabric shown is according to certain embodiments of the invention, having a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a continuous high-melting-point region and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions dispersed throughout the high-melting-point region. Detailed Implementation

[0009] Various embodiments of the invention will now be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, of the embodiments of the invention. In fact, these inventions 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 to enable this disclosure to meet applicable legal requirements. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly indicates otherwise.

[0010] This invention generally relates to a method for forming a nonwoven fabric that has undergone a heat-setting (HSO) operation. The nonwoven web may comprise multiple individual melt-spun fibers, such as monocomponent fibers with different melt initiation temperatures of different groups, bicomponent fibers having high-melting-point and low-melting-point components, and different groups of bicomponent fibers each having corresponding high-melting-point and low-melting-point components, which are collected directly or indirectly onto a moving collection belt. The nonwoven web can then be subjected to HSO, which involves subjecting the nonwoven web to high temperatures to at least increase the viscosity of the lowest melting-point material present in the nonwoven web, while the nonwoven web is held under sufficient compression or constraint to reduce thermal shrinkage during subsequent consolidation. HSO may include, for example, using heated pressure rollers or hot air knives to increase the viscosity of the lowest melting-point material in the nonwoven web. HSO advantageously “heat-sets” higher melting-point materials to reduce shrinkage during heating cycles that maintain the web width and additional shrinkage in subsequent bonding cycles such as calendering, ultrasonic, chemical, or hot air bonding. HSO achieves this benefit by modifying the path of the collection belt using, for example, a porous roller, allowing transport of the collected fiber web (before any heating is applied), and the fiber web path minimally surrounds the roller, for example, 180° to 340°, preferably about 270°. In this way, the deposition of the unconsolidated nonwoven fiber web remains undisturbed. The nonwoven fiber web (fiber web) is captured between the layup belt (e.g., the collection belt) and the roller, where it is subsequently heated (annealed) to achieve thermal setting of the polymer at a higher melting temperature. Additionally, HSO may include a cooling section or step in which a smaller radial length of the nonwoven fiber web is cooled before leaving the "roll gap" formed by the contact between the belt and the roller. According to certain embodiments of the invention, this method provides the integrity of the nonwoven fiber web by softening / melting the lower melting point polymer fibers (or fiber components), thereby providing pre-bonding for further unsupported transport to the final bonding unit. The final consolidation or bonding unit may include, for example, hot air bonding, hot calendering, ultrasonic bonding, or chemical bonding. According to certain embodiments of the invention, the method provides undisturbed nonwoven web shaping by slightly bonding the nonwoven web under slight compression, while also allowing a heat setting process to avoid shrinkage of any mixture of fibers with high glass transition temperatures.According to certain embodiments of the invention, fiber configurations with different melting points can be produced by bicomponent fibers or blends having monocomponent fibers with different melting points produced by bicomponent extrusion, but can also be produced by multiple monocomponent or bicomponent fibers with different processing conditions, as mentioned above, relating to the melt spinning die disclosed in co-owned and co-pending application 63 / 427,584 filed November 23, 2022, which is converted into co-owned and co-pending application 18 / 514,141 filed November 20, 2023, the entire contents of which are incorporated herein by reference, to produce fibers with different melting temperatures from a single die and / or a single polymer composition.

[0011] In this regard, fibers extruded from their respective capillaries, such as those from a melt-spinning die disclosed in common and common pending application 63 / 427,584 (which is converted into common and common pending application 18 / 514,141 filed November 20, 2023), can define their respective zones or regions, providing a resulting nonwoven fiber web having fibers formed of polymeric material and a range of fibers with different melting points and / or melting ranges, which can be distinct and / or unique (e.g., non-overlapping melting ranges) and / or have overlapping melting point ranges. By way of example only, a single spinneret may include a first orifice zone and a second orifice zone. Thus, fibers formed or extruded from one zone will have the greatest crystalline properties or degree and exhibit the highest melting point, while fibers formed or extruded from another zone will have the least crystalline properties or degree (e.g., amorphous) and exhibit the lowest melting point. In this respect, the resulting nonwoven fiber web (e.g., spunbond fiber web) will consist of at least two separate fiber groups, the fiber groups being determined by crystallinity and / or melting point or melting range. Therefore, this formed nonwoven fiber web can first be heat-treated (e.g., annealing, light compaction) to a temperature sufficient to melt the fibers formed from the second region of the capillary (e.g., fibers with the lowest melting point), and the nonwoven fiber web can be lightly compacted to impart sufficient durability for subsequent processing (e.g., conveying, combining with other materials such as membranes, nonwovens, etc.). A final consolidation step can then be performed by heating the fibers to a temperature that more completely melts the fibers to provide a stronger level of consolidation. The terms “basically” or “substantially” may cover the total amount specified in certain embodiments of the invention, or the total amount that is largely but not specified in other embodiments of the invention (e.g., 95%, 96%, 97%, 98%, or 99% of the specified total amount).

[0012] The term "polymer" or "polymerized," as used interchangeably herein, may include homopolymers, copolymers such as block, graft, random and alternating copolymers, terpolymers, etc., and their blends and modifications. Furthermore, unless specifically limited otherwise, the term "polymer" or "polymerized" shall include all possible structural isomers; stereoisomers, including but not limited to geometric isomers, optical isomers, or enantiomers; and / or any chiral molecular configuration of such polymer or polymeric material. These configurations include, but are not limited to, isotactic, syndiotactic, and atactic configurations of such polymer or polymeric material. The term "polymer" or "polymerized" shall also include polymers made from various catalyst systems, including but not limited to Ziegler-Natta catalyst systems and metallocene / single-center catalyst systems. According to certain embodiments of the invention, the term "polymer" or "polymerized" shall also include polymers produced by fermentation methods or of biological origin.

[0013] As used herein, the terms "nonwoven" and "nonwoven fiber web" can include fiber webs having a structure of single fibers, filaments, and / or threads interwoven in an interlaced manner but not in a repeating manner as identifiable in knitted or woven fabrics. According to certain embodiments of the invention, nonwoven fabrics or fiber webs can be formed by any method conventionally known in the art, such as meltblowing, spunbonding, needle punching, hydraulic entanglement, air-laid web formation, and bonded carding. As used herein, a "nonwoven fiber web" can include multiple individual fibers that have not undergone a consolidation process. In some cases, a "nonwoven fiber web" can include multiple layers, such as one or more spunbond layers and / or one or more meltblown layers. For example, a "nonwoven fiber web" can include a spunbond-meltblown-spunbond structure.

[0014] As used herein, the terms “fabric” and “nonwoven fabric” can include fiber webs in which multiple fibers are mechanically entangled or interconnected, fused together and / or chemically bonded together. For example, a bonding or consolidation process can be applied to a nonwoven fiber web of individually laid fibers to bond at least a portion of the individual fibers together to form a bonded (e.g., cohesive) fiber web of interconnected fibers.

[0015] As used herein, the terms "consolidated" and "consolidated" can include bringing together at least a portion of the fibers of a nonwoven fiber web to bring them closer together or attach them therebetween (e.g., thermally fused together, chemically bonded together, and / or mechanically entangled together) to form one or more bonded sites that, compared to an unconsolidated fiber web, increase resistance to external forces (e.g., abrasion and tension). For example, one or more bonded sites can include discrete or localized regions of the fiber web material that have been softened or melted and optionally subsequently or simultaneously compressed to create discrete or localized deformations within the fiber web material. Furthermore, the term "consolidated" can include the entire nonwoven fiber web that has been processed such that at least a portion of the fibers are brought closer together or attached therebetween (e.g., thermally fused together, chemically bonded together, and / or mechanically entangled together), for example by thermal bonding or mechanical entanglement (e.g., hydraulic entanglement), as just a few examples. Additionally, the terms "consolidated" and "consolidated" can include bonding operations performed by hot air bonding. As used herein, the terms "hot-air bonded" and "hot-air bonded" can include nonwoven fiber webs bonded by an bonding method, wherein hot air is used to fuse fibers at the surface of the fiber web and optionally within the fiber web. By way of example only, the hot air can be blown through the web in a conveyor-type oven or drawn through the web as it passes through a porous drum, creating a vacuum. The temperature and rate of the hot air are parameters that can determine the level or extent of bonding in the nonwoven fiber web. According to certain embodiments of the invention, the temperature of the hot air can be high enough to melt, induce flow, and / or fuse multiple fibers (e.g., amorphous fibers) having a lower melting point temperature or a lower melting point temperature starting point to multiple fibers (e.g., semi-crystalline or crystalline fibers) having a higher melting point temperature or a lower melting point temperature starting point. According to certain embodiments of the invention, such a fiber web can be considered a "bonded nonwoven material," a "nonwoven fabric," or simply a "fabric."

[0016] As used in this article, "melt spinning" or "melt spinning" usually refers to fiber forming methods such as spunbond or meltblown.

[0017] As used herein, the term "spunbond" can include fibers formed by extruding molten thermoplastic material as fibers from a plurality of fine, typically circular capillaries of a spinneret, followed by a rapid reduction in the diameter of the extruded fibers. According to embodiments of the invention, spunbond fibers are generally non-sticky upon deposition onto a collection surface and can be substantially continuous as disclosed and described herein. It should be noted that spunbond materials used in certain composites of the invention can include nonwoven materials described in the literature as SPINLACE®. Spunbond fibers, for example, comprise continuous fibers.

[0018] As used herein, the term "continuous fiber" refers to a fiber that is not cut from its original length before being formed into a nonwoven fiber web or nonwoven fabric. The average length of a continuous fiber can be greater than about 15 centimeters to greater than one meter, and can be up to the length of the resulting fiber web or fabric. For example, the continuous fiber used herein may include fibers in which the fiber length is at least 1,000 times greater than the average fiber diameter, such as at least about 5,000, 10,000, 50,000, or 100,000 times greater than the average fiber diameter.

[0019] As used herein, the term "longitudinal" or "MD" refers to the direction in which the fabric is produced or conveyed. The term "transverse" or "CD" as used herein refers to the direction in which the fabric is substantially perpendicular to the MD.

[0020] According to certain embodiments of the present invention, a method for forming a nonwoven fabric is provided, comprising the step of directly or indirectly depositing at least a first nonwoven layer comprising a first plurality of interwoven individual melt-spun fibers onto a moving collection belt to provide a precursor nonwoven fiber web having an average initial transverse (CD) width and / or an average initial basis weight. The first plurality of interwoven individual melt-spun fibers may comprise (a) a combination of a first group of monocomponent fibers and a second group of monocomponent fibers, the first group of monocomponent fibers having a first melt initiation temperature and the second group of monocomponent fibers having a second melt initiation temperature below the first melt initiation temperature; (b) a bicomponent fiber comprising a first component and a second component, the first component having a first melt initiation temperature and the second component having a second melt initiation temperature below the first melt initiation temperature; (c) a combination of a first group of bicomponent fibers and a second group of bicomponent fibers, the first group of bicomponent fibers having a first higher melting point component and a first lower melting point component, the second group of bicomponent fibers having a second higher melting point component and a second lower melting point component that begins to melt before the first lower melting point component; or (d): any combination of (a)-(c). The method may further include conveying a precursor nonwoven fiber web through a heat-setting operation (HSO), the heat-setting operation comprising (a) directly or indirectly constraining the precursor nonwoven fiber web within a heat-setting roller gap defined between a moving collection belt and a portion of an opposing surface, such as a portion of a heat-setting device, to mitigate relative movement of individually melt-spun fibers during HSO, and (b) subjecting the precursor nonwoven fiber web to a high temperature sufficient to increase the viscosity of a second component of the second set of monocomponent fibers and / or bicomponent fibers having a second melt initiation temperature, to provide a second lower melting point component of the intermediate nonwoven fabric and / or the second set of bicomponent fibers. The method may further include removing the intermediate nonwoven fabric from the HSO, wherein the intermediate nonwoven fabric has an average post-heat-setting CD width and / or an average post-heat-setting basis weight, and consolidating the intermediate nonwoven fabric to provide a nonwoven fabric having an average final CD width and / or an average final basis weight. According to certain embodiments of the invention, HSO may lightly bond or consolidate a portion of the melt-spun fibers together to provide sufficient integrity for processing, while the consolidation step bonds the melt-spun fibers together more thoroughly to provide a final nonwoven fabric that is significantly more durable and stronger than the intermediate nonwoven fabric formed after HSO.

[0021] Figure 1-4 Each illustration shows a schematic diagram of a corresponding general method according to certain embodiments of the invention. Although Figure 1-4Two melt-spinning rollers are shown, but this is for illustrative purposes only; for example, one to ten individual rollers may be used. Each method includes HSO and a consolidation or bonding unit located downstream of HSO. These individual units can utilize any hot fluid in the process (e.g., hot air or steam) to achieve different degrees of melt flow and adhesion from lower melting point fibers (or fiber components) to higher melting point fibers (or fiber components) to achieve different degrees of bonding. For example, the HSO step is configured to achieve thermally induced annealing, which has a temperature above the glass transition temperature of the higher polymer for a limited time, during which the physical movement of the nonwoven fiber web is restricted, wherein the high temperature is also above the softening point or melting point (e.g., melt initiation temperature) of the lower melting point polymer that can be pre-bonded. Additionally, the “HSO” step may include a section for cooling the nonwoven material before the physical constraints are released and removed from the HSO. According to certain embodiments of the invention, the cooling step can particularly help to complete the heat setting process of the high-temperature polymer (e.g., a higher melt initiation temperature associated with one of the groups of single-component fibers, bicomponent fibers, etc.) and ensure the integrity of the fiber web for further transport to final bonding.

[0022] For example, Figure 1 Method 1 is illustrated, comprising two spunbond rollers 3, 5, which deposit continuously melt-spun fibers 4, 6 onto a moving collection belt 7 to form an unconsolidated nonwoven web 10, which is conveyed into and through an HSO 20. The nonwoven web 10 is physically constrained by a heat-setting roller gap 22 between the moving collection belt 7 and a portion of the HSO 20, and is maintained at a substantially constant tension or physical constraint on the nonwoven web until exiting the HSO to provide an intermediate nonwoven fabric 30. Figure 1 The HSO includes a porous hot fluid roller that can rotate or remain stationary, having a heating section 24 and a cooling section 28. An intermediate nonwoven fabric 30 can then be conveyed to an bonding unit 50 for consolidation to provide a final nonwoven fabric 60. The bonding unit may be... Figure 1 The bonding roller is shown. Optionally, the final nonwoven fabric can be collected on the winding roller 70. Figure 2 It shows the relationship with Figure 1 Essentially the same as another method 1, but HSO 20 includes a hot air knife instead. Figure 1 A perforated roller. Figure 3 and Figure 4 respectively with Figure 1 and Figure 2 Basically the same, but the bonding unit 50 is replaced with a hot calendering operation.

[0023] According to certain embodiments of the invention, the high temperature associated with HSO can be within about 7°C below the second melt initiation temperature or the second lower melting point component of the second group of bicomponent fibers, for example, within any of the following ranges: the melt temperature of the second lower melting point component of the second group of bicomponent fibers is 6°C, 5°C, 4°C, 3°C, and 2°C lower than the second melt initiation temperature. Alternatively or additionally, subjecting the precursor nonwoven fiber web to the high temperature includes a residence time of about 3 seconds to about 120 seconds, for example, at least about any of the following: 3, 5, 8, 10, 15, 20, 30, 40, 50, and 60 seconds, and / or at most about any of the following: 120, 100, 90, 80, 70, and 60 seconds. Alternatively or concurrently, the HSO may also include a cooling step that reduces the temperature of the precursor nonwoven fiber web to about 20°C to about 40°C before it leaves the heat-setting roll gap, for example, at least about any one of the following: 20, 22, 25, 28 and 30°C, and / or at most about any one of the following: 40, 38, 35, 32 and 30°C.

[0024] According to certain embodiments of the invention, the HSO includes a porous rotating or stationary roller, wherein the heat-setting roller gap is defined by the roller and a moving collection belt. For example, the heat-setting roller gap defines a travel path of the precursor nonwoven web extending from about 180° to about 340°, for example, at least about any of the following: 180°, 190°, 200°, 210°, 220°, 230°, 240°, 250°, 260°, and 270°, and / or at most about any of the following: 340°, 330°, 320°, 310°, 300°, 290°, 280°, and 270°. Additionally or alternatively, the roller (e.g., stationary or rotating) also includes a cooling section, wherein the precursor nonwoven web is conveyed through a heating section before being conveyed through the cooling section. In this respect, the heating section comprises about 70% to about 95% of the travel path, for example at least about any one of the following: 70, 75, 80, and 85%, and / or at most about any one of the following: 95%, 90%, and 85%, and the cooling section comprises about 5% to about 30% of the travel path, for example at least about any one of the following: 5, 10, and 15%, and / or at most about any one of the following: 30, 25, 20, and 15%. According to certain embodiments of the invention, the heating section includes discharging heated air from the heating section to a corresponding portion of the travel path or to a hot-heated calender.

[0025] According to certain embodiments of the invention, the HSO includes a linear hot air bonding unit comprising a heating section and a cooling section, wherein a heat-setting roller gap defines a travel path of the precursor nonwoven web between the linear hot air bonding unit and a moving collection belt, and wherein the precursor nonwoven web is conveyed through the heating section before being conveyed through the cooling section. For example, the heating section comprises about 70% to about 95% of the travel path, for example at least about any one of the following: 70, 75, 80, and 85%, and / or at most about any one of the following: 95%, 90%, and 85%, and the cooling section comprises about 5% to about 30% of the travel path, for example at least about any one of the following: 5, 10, and 15%, and / or at most about any one of the following: 30, 25, 20, and 15%.

[0026] According to certain embodiments of the invention, the consolidation of the intermediate nonwoven fabric may include various consolidation methods, such as hot calendering, hot air bonding, ultrasonic bonding, hot zone bonding, chemical bonding, or any combination thereof, wherein the first plurality of interwoven individual meltspun fibers may optionally be subjected to a high temperature equal to or greater than a second melt initiation temperature or melting point associated with a second higher melting point component of the second set of bicomponent fibers, and optionally wherein the high temperature is lower than a second melt initiation temperature or melting point associated with a higher melting point component of the first set of bicomponent fibers. For example, according to certain embodiments of the invention, the higher melting point fiber or fiber component may retain a substantially undeformed shape.

[0027] The step of consolidating the intermediate nonwoven fabric may include a thermocalendering operation that imparts a plurality of discrete bonded portions defining a bonding region, wherein the bonded region may include about 3% to about 30%, for example at least about any one of the following: 3, 5, 6, 8, 10, 12, 15, 18 and 20%, and / or at most about any one of the following: 30, 28, 26, 25, 24, 22 and 20%. Alternatively, consolidating the intermediate nonwoven fabric may include a thermal bonding operation, wherein at least the first outermost surface is fully bonded to define a continuous bond, thereby defining a microporous membrane structure.

[0028] According to certain embodiments of the invention, the average heat-set CD width is at least about 95% of the average initial CD width, for example, at least about any one of the following: 95, 96, 97, 98, 99, and 99.5% of the average initial CD width, and / or at most about any one of the following: 100, 99.9, 99.8, 99.7, 99.6, and 99.5% of the average initial CD width. Additionally or alternatively, the average heat-set basis weight is at least about 95% of the average initial basis weight, for example, at least about any one of the following: 95, 96, 97, 98, 99, and 99.5% of the average initial basis weight, and / or at most about any one of the following: 100, 99.9, 99.8, 99.7, 99.6, and 99.5% of the average initial basis weight. Alternatively or alternatively, the average final CD width is at least about 95% of the average heat-set CD width, for example, at least about any one of the following: 95, 96, 97, 98, 99, and 99.5% of the average heat-set CD width, and / or at most about any one of the following: 100, 99.9, 99.8, 99.7, 99.6, and 99.5% of the average heat-set CD width. Alternatively or alternatively, the average final basis weight is at least about 95% of the average heat-set basis weight, for example, at least about any one of the following: 95, 96, 97, 98, 99, and 99.5% of the average heat-set basis weight, and / or at most about any one of the following: 100, 99.9, 99.8, 99.7, 99.6, and 99.5% of the average heat-set basis weight. Alternatively or alternatively, the average final CD width is at least about 95% of the average initial CD width, for example, at least about any one of the following: 95, 96, 97, 98, 99, and 99.5% of the initial CD width, and / or at most about any one of the following: 100, 99.9, 99.8, 99.7, 99.6, and 99.5% of the average initial CD width. Alternatively or alternatively, the average final weight is at least about 95% of the average initial weight, for example, at least about any one of the following: 95, 96, 97, 98, 99, and 99.5% of the average initial weight, and / or at most about any one of the following: 100, 99.9, 99.8, 99.7, 99.6, and 99.5% of the average initial weight.

[0029] According to certain embodiments of the present invention, a nonwoven fiber web or nonwoven fabric may include a first plurality of individual melt-spun fibers, the first plurality of individual melt-spun fibers comprising a first group of monocomponent fibers or a first group of bicomponent fibers having a first melt initiation temperature and a second group of monocomponent fibers or a first group of bicomponent fibers having a second melt initiation temperature lower than the first melt initiation temperature, wherein the first group of monocomponent fibers or the first group of bicomponent fibers defines at least one first region, and the second group of monocomponent fibers or the first group of bicomponent fibers defines at least one second region, and wherein the first plurality of individual melt-spun fibers are formed from a single polymer composition.

[0030] According to certain embodiments of the invention, a first higher melting point component of the first group of monocomponent fibers or a first group of bicomponent fibers has a first melting point range, and a second lower melting point component of the second group of monocomponent fibers or a second group of bicomponent fibers has a second melting point range; wherein the first melting point range and the second melting point range do not overlap. For example, the difference between the closest values ​​of the first melting point range and the second melting point range can be from 2 to 60°C, for example, at least about any of the following: 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, and 20°C, and / or at most about any of the following: 60, 50, 40, 30, 28, 25, 22, and 20°C. Additionally or alternatively, during the consolidation of the intermediate nonwoven fabric, the second lower melting point component of the second group of monocomponent fibers or the second group of bicomponent fibers deforms from the initial spinning cross section and fuses with the first group of monocomponent fibers or the second group of bicomponent fibers.

[0031] According to certain embodiments of the present invention, such as Figure 5 As shown, the nonwoven fabric 100 may include a first group of monocomponent fibers or a first group of bicomponent fibers defining at least a first higher melting point region 110, and a second group of monocomponent fibers or a second group of bicomponent fibers defining at least a lower melting point region 210. Figure 6 For example, a nonwoven fabric 100 according to certain embodiments of the invention is shown, comprising a first set of melt-spun fibers (e.g., a first set of monocomponent melt-spun fibers and / or a first set of bicomponent fibers) defining two high-melting-point regions 110a, 110b, and a second set of melt-spun fibers (e.g., a second set of monocomponent melt-spun fibers and / or a second set of bicomponent fibers) defining a low-melting-point region 210. In this respect, the first set of monocomponent fibers or the first set of bicomponent fibers may define two separate higher-melting-point regions, including, for example, a first outermost surface and / or a second outermost surface of the nonwoven fabric. Figure 6 In the second group of monocomponent fibers or the second group of bicomponent fibers, at least a first lower melting point region 210 is defined, which is adjacent to a first higher melting point region, a second higher melting point region, or both.

[0032] The resulting nonwoven fabric may have a total basis weight of about 10 g / m² (gsm) to about 200 gsm, for example, at least about any of the following: 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 45 and 50 gsm, and / or at most about any of the following: 200, 180, 150, 120, 100, 80, 70, 60 and 50 gsm. Additionally or alternatively, the first group of monocomponent fibers or the first group of bicomponent fibers constitute about 50 to about 90% by weight of the total basis weight, for example, at least about any of the following: 50, 55, 60, 65 and 70% by weight of the total basis weight, and / or at most about any of the following: 90, 85, 80, 75 and 70% by weight of the total basis weight. Alternatively or concurrently, the second group of monocomponent fibers or the second group of bicomponent fibers constitute about 10% to about 50% of the total basis weight, for example, at least about any one of the following: 10, 15, 20, 25 and 30% of the total basis weight, and / or at most about any one of the following: 50, 45, 40, 35 and 30% of the total basis weight.

[0033] According to certain embodiments of the invention, the second set of monocomponent fibers or the second set of bicomponent fibers may define at least a first lower melting point region comprising a first outermost surface of the nonwoven fabric. Alternatively or additionally, the second set of monocomponent fibers or the second set of bicomponent fibers may also define a second lower melting point region comprising a second outermost surface of the nonwoven fabric. Alternatively or additionally, the first set of monocomponent fibers or the first set of bicomponent fibers may define at least one higher melting point region adjacent to the first lower melting point region, the second lower melting point region, or both. For example, Figure 7 This illustrates one such nonwoven fabric. Figure 7A nonwoven fabric 100 according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining an internal high-melting-point region 110 and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining two low-melting-point regions 210a, 210b. Alternatively or additionally, the nonwoven fabric may have a total basis weight of about 10 g / m² to about 200 g / m², for example at least about any of the following: 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 45, and 50 g / m², and / or at most about any of the following: 200, 180, 150, 120, 100, 80, 70, 60, and 50 g / m². Alternatively or alternatively, the first group of monocomponent fibers or the first group of bicomponent fibers constitutes about 50 to about 90% by weight of the total basis weight, for example, at least about any one of the following: 50, 55, 60, 65, and 70% by weight of the total basis weight, and / or at most about any one of the following: 90, 85, 80, 75, and 70% by weight of the total basis weight. Alternatively or alternatively, the second group of monocomponent fibers or the second group of bicomponent fibers constitutes about 10% to about 50% by weight of the total basis weight, for example, at least about any one of the following: 10, 15, 20, 25, and 30% by weight of the total basis weight, and / or at most about any one of the following: 50, 45, 40, 35, and 30% by weight of the total basis weight.

[0034] According to certain embodiments of the present invention, a first group of monocomponent fibers or a first group of bicomponent fibers may define a plurality of first higher melting point regions, and a second group of monocomponent fibers or a second group of bicomponent fibers may define a plurality of first lower melting point regions. For example, the plurality of first higher melting point regions and the plurality of first lower melting point regions may be positioned alternately along the longitudinal direction, the z-direction perpendicular to the longitudinal direction and the transverse direction of the nonwoven fabric, or both. Alternatively, the plurality of first higher melting point regions and the plurality of first lower melting point regions may be positioned alternately along the transverse direction, the z-direction perpendicular to the transverse direction and the longitudinal direction of the nonwoven fabric. According to certain embodiments of the present invention, the plurality of first higher melting point regions and the plurality of first lower melting point regions are positioned alternately along the transverse and longitudinal directions. According to certain embodiments of the present invention, the plurality of first higher melting point regions and the plurality of first lower melting point regions are also positioned alternately in the z-direction of the nonwoven fabric, wherein the z-direction is perpendicular to the transverse and longitudinal directions. Alternatively or alternatively, the nonwoven fabric may have a total basis weight of about 10 g / m² (gsm) to about 200 gsm, for example at least about any one of the following: 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 45 and 50 gsm, and / or at most about any one of the following: 200, 180, 150, 120, 100, 80, 70, 60 and 50 gsm. Alternatively or alternatively, the first group of monocomponent fibers or the first group of bicomponent fibers constitute about 50 to about 90% by weight of the total basis weight, for example at least about any one of the following: 50, 55, 60, 65 and 70% by weight of the total basis weight, and / or at most about any one of the following: 90, 85, 80, 75 and 70% by weight of the total basis weight. Alternatively or concurrently, the second group of monocomponent fibers or the second group of bicomponent fibers constitute about 10% to about 50% of the total basis weight, for example, at least about any one of the following: 10, 15, 20, 25 and 30% of the total basis weight, and / or at most about any one of the following: 50, 45, 40, 35 and 30% of the total basis weight.

[0035] For example, Figure 8 A nonwoven fabric 100 according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions 110a, 110b and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions 210a, 210b, wherein the high-melting-point regions and the low-melting-point regions are positioned alternately along the z-direction.

[0036] For example, Figure 9Another nonwoven fabric 100 according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high melting point regions 100a-100c and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low melting point regions 210a, 210b, wherein the high melting point regions and the low melting point regions are positioned alternately along the z-direction.

[0037] For example, Figure 10 A nonwoven fabric 100 according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions 110a-110e and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions 210a-210f, wherein the high-melting-point regions and the low-melting-point regions are positioned laterally in an alternating manner.

[0038] For example, Figure 11 A nonwoven fabric 100 according to certain embodiments of the present invention is shown, comprising a first group of melt-spun fibers (e.g., a first group of monocomponent melt-spun fibers and / or a first group of bicomponent fibers) defining a plurality of high-melting-point regions 110a-110n and a second group of melt-spun fibers (e.g., a second group of monocomponent melt-spun fibers and / or a second group of bicomponent fibers) defining a plurality of low-melting-point regions 210a-210l, wherein the high-melting-point regions and the low-melting-point regions are positioned alternately along the z-direction and laterally.

[0039] According to certain embodiments of the invention, a first group of monocomponent fibers or a first group of bicomponent fibers may define a higher melting point region comprising a continuous area, and a second group of monocomponent fibers or a second group of bicomponent fibers may define a plurality of lower melting point regions comprising individual islands dispersed throughout the continuous area. Alternatively, a second group of monocomponent fibers or a second group of bicomponent fibers may define a low melting point region comprising a continuous area, and a first group of monocomponent fibers or a first group of bicomponent fibers may define a plurality of high melting point regions comprising individual islands dispersed throughout the continuous area. According to certain embodiments of the invention, the nonwoven fabric has a total basis weight of about 10 g / m² to about 200 g / m², for example at least about any one of the following: 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 45 and 50 g / m², and / or at most about any one of the following: 200, 180, 150, 120, 100, 80, 70, 60 and 50 g / m². Alternatively or alternatively, the first group of monocomponent fibers or the first group of bicomponent fibers constitutes about 50 to about 90% by weight of the total basis weight, for example, at least about any one of the following: 50, 55, 60, 65, and 70% by weight of the total basis weight, and / or at most about any one of the following: 90, 85, 80, 75, and 70% by weight of the total basis weight. Alternatively or alternatively, the second group of monocomponent fibers or the second group of bicomponent fibers constitutes about 10% to about 50% by weight of the total basis weight, for example, at least about any one of the following: 10, 15, 20, 25, and 30% by weight of the total basis weight, and / or at most about any one of the following: 50, 45, 40, 35, and 30% by weight of the total basis weight.

[0040] For example, Figure 12 A nonwoven fabric 100 according to certain embodiments of the present invention is shown, having a second set of melt-spun fibers (e.g., a second set of monocomponent melt-spun fibers and / or a second set of bicomponent fibers) defining a continuous low-melting-point region 210 and a first set of melt-spun fibers (e.g., a first set of monocomponent melt-spun fibers and / or a first set of bicomponent fibers) defining a plurality of high-melting-point regions 110a-110e dispersed throughout the low-melting-point region.

[0041] For example, Figure 13 A nonwoven fabric 100 according to certain embodiments of the present invention is shown, having a first set of melt-spun fibers (e.g., a first set of monocomponent melt-spun fibers and / or a first set of bicomponent fibers) defining a continuous high-melting-point region 110 and a second set of melt-spun fibers (e.g., a second set of monocomponent melt-spun fibers and / or a second set of bicomponent fibers) defining a plurality of low-melting-point regions 210a-210i dispersed throughout the high-melting-point region.

[0042] According to certain embodiments of the invention, the first group of monocomponent fibers or the first group of bicomponent fibers includes a circular outermost cross-section, a non-circular outermost cross-section, or both. For example, the average diameter of the first group of monocomponent fibers or the first group of bicomponent fibers is from about 8 to about 40 micrometers, for example, at least about any one of the following: 8, 10, 12, 15, 18, and 10 micrometers, and / or at most about any one of the following: 40, 28, 35, 32, 30, 28, 25, 22, and 20 micrometers. Alternatively or additionally, the first group of monocomponent fibers or the first group of bicomponent fibers may include a circular outermost cross-section having an aspect ratio of 0.8 to 1.2, for example, about 0.8, 0.9, and 1, and / or at most about 1.2, 1.1, and 1.

[0043] According to certain embodiments of the invention, the first group of monocomponent fibers or the first group of bicomponent fibers may include a non-circular outermost cross section having an aspect ratio of at least 1.5, for example at least about any of the following: 1.5, 2, 3, 4 and 5, and / or at most about any of the following: 10, 9, 8, 7, 6 and 5.

[0044] According to certain embodiments of the invention, the first group of monocomponent fibers or the first group of bicomponent fibers comprises a combination of circular outermost cross-section fibers and non-circular outermost cross-section fibers. For example, the circular outermost cross-section fibers account for about 1% to about 99% of the total number of the first group of monocomponent fibers or the first group of bicomponent fibers, for example, at least about any one of the following: 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% of the total number of the first group of monocomponent fibers or the first group of bicomponent fibers, and / or at most about any one of the following: 99, 98, 95, 90, 85, 80, 75, 70, 65, 60, 55 and 50% of the total number of the first group of monocomponent fibers or the first group of bicomponent fibers. Alternatively or concurrently, the outermost circular cross-section fibers comprise 1% to approximately 99% of the total number of the first group of monocomponent fibers or the first group of bicomponent fibers, for example, at least approximately any one of the following: 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50% of the total number of the first group of monocomponent fibers or the first group of bicomponent fibers, and / or at most approximately any one of the following: 99, 98, 95, 90, 85, 80, 75, 70, 65, 60, 55, and 50% of the total number of the first group of monocomponent fibers or the first group of bicomponent fibers.

[0045] According to certain embodiments of the invention, the second group of monocomponent fibers or the second group of bicomponent fibers comprises a circular outermost cross-section, a non-circular outermost cross-section, or both. Alternatively or additionally, the second group of monocomponent fibers or the second group of bicomponent fibers comprises an average diameter of about 8 to about 40 micrometers, for example, at least about any one of the following: 8, 10, 12, 15, 18, and 10 micrometers, and / or at most about any one of the following: 40, 28, 35, 32, 30, 28, 25, 22, and 20 micrometers. Alternatively or additionally, the second group of monocomponent fibers or the second group of bicomponent fibers may comprise a circular outermost cross-section having an aspect ratio of 0.8 to 1.2, for example, about 0.8, 0.9, and 1, and / or at most about 1.2, 1.1, and 1.

[0046] According to certain embodiments of the invention, the second group of monocomponent fibers or the second group of bicomponent fibers includes a non-circular outermost cross section having an aspect ratio of at least 1.5, for example at least about any of the following: 1.5, 2, 3, 4 and 5, and / or at most about any of the following: 10, 9, 8, 7, 6 and 5.

[0047] According to certain embodiments of the invention, the second group of monocomponent fibers or the second group of bicomponent fibers comprises a combination of circular outermost cross-section fibers and non-circular outermost cross-section fibers. For example, the circular outermost cross-section fibers account for approximately 1% to 99% of the total number of the second group of monocomponent fibers or the second group of bicomponent fibers, for example, at least about any one of the following: 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% of the total number of the second group of monocomponent fibers or the second group of bicomponent fibers, and / or at most about any one of the following: 99, 98, 95, 90, 85, 80, 75, 70, 65, 60, 55 and 50% of the total number of the second group of monocomponent fibers or the second group of bicomponent fibers. Alternatively or concurrently, the outermost circular cross-section fibers comprise 1% to approximately 99% of the total number of the second group of monocomponent fibers or the second group of bicomponent fibers, for example, at least approximately any one of the following: 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50% of the total number of the second group of monocomponent fibers or the second group of bicomponent fibers, and / or at most approximately any one of the following: 99, 98, 95, 90, 85, 80, 75, 70, 65, 60, 55, and 50% of the total number of the second group of monocomponent fibers or the second group of bicomponent fibers.

[0048] According to certain embodiments of the present invention, the first group of bicomponent fibers and the second group of bicomponent fibers may comprise a single polymer composition, wherein the single polymer composition comprises a polymer component, the polymer component comprising a polyolefin or a copolymer thereof, a polyester or a copolymer thereof, a polyamide or a copolymer thereof, or a biopolymer, such as polylactic acid; or wherein the first higher melting point component and the first lower melting point component of the first group of bicomponent fibers independently comprise polymer components, the polymer components comprising a polyolefin or a copolymer thereof, a polyester or a copolymer thereof, a polyamide or a copolymer thereof, or a biopolymer, such as polylactic acid; or wherein the second higher melting point component and the second lower melting point component of the second group of bicomponent fibers independently comprise polymer components, the polymer components comprising a polyolefin or a copolymer thereof, a polyester or a copolymer thereof, a polyamide or a copolymer thereof, or a biopolymer, such as polylactic acid. For example, the polyolefin may comprise polypropylene, its copolymers, polyethylene, its copolymers, or blends thereof.

[0049] As described above, the resulting nonwoven fabric may include hot-air bonded nonwoven fabric, zone-bonded nonwoven fabric, or hot-calendered nonwoven fabric with multiple discrete bonding points. According to some embodiments of the invention, the second group of monocomponent fibers or the second group of bicomponent fibers has a cross-section deformed due to at least partial melting, flow, and bonding to the first group of monocomponent fibers or the first group of bicomponent fibers. According to some embodiments of the invention, the first group of monocomponent fibers has an undeformed cross-section.

[0050] According to certain embodiments of the invention, the first plurality of intermediate individual melt-spun fibers include melt-spun fibers, spunbond fibers, or both. Alternatively or additionally, the method may include depositing one or more additional nonwoven layers, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 additional melt-spun fiber layers, directly or indirectly onto the first nonwoven layer. Alternatively or additionally, the one or more additional nonwoven layers independently comprise (a), (b), or (c) as described above.

[0051] In another aspect, the present invention provides a heat-set nonwoven fabric comprising at least a first plurality of interwoven individual melt-spun fibers, the first plurality of interwoven individual melt-spun fibers comprising (a) a combination of a first group of monocomponent fibers and a second group of monocomponent fibers, the first group of monocomponent fibers having a first melt initiation temperature and the second group of monocomponent fibers having a second melt initiation temperature lower than the first melt initiation temperature; (b) a bicomponent fiber comprising a first component and a second component, the first component having a first melt initiation temperature and the second component having a second melt initiation temperature lower than the first melt initiation temperature; (c) a combination of a first group of bicomponent fibers and a second group of bicomponent fibers, the first group of bicomponent fibers having a first higher melting point component and a first lower melting point component, the second group of bicomponent fibers having a second higher melting point component and a second lower melting point component that begins to melt before the first lower melting point component; or (d): any combination of (a)-(c). The nonwoven fabric may be a through-air-bonded nonwoven fabric, a chemically bonded nonwoven fabric, a mechanically bonded nonwoven fabric, and / or a thermally bonded nonwoven fabric. In this regard, nonwoven fiber webs (e.g., spunbond fiber webs) can be consolidated by a through-fluid bonding method (e.g., the fluid including hot air or steam), wherein optionally, only lower melting point fibers (or components) are softened, melted, and / or flowed through a portion of the nonwoven fiber web to form an adhesive with the higher melting point fibers. In this respect, according to certain embodiments of the invention, the structural integrity of the resulting nonwoven fabric can be provided by the higher melting point fibers (or higher melting point fiber components), which can remain in an undeformed or substantially undeformed state (e.g., the cross-section of the high melting point fibers or fiber components remains the same or substantially the same before, during, and after the consolidation operation). Conversely, low melting point fibers (or fiber components) may have a deformed cross-section or be individually indistinguishable as individual fibers due to melting and / or flow to provide an adhesive mechanism for consolidation. For example, low melting point fibers (or fiber components) may at least partially melt and flow through at least some of the gaps defined between the high melting point fibers. As low-melting-point fibers (or fiber components) flow through the gaps between high-melting-point fibers, deformed and flowing low-melting-point fibers (e.g., less crystalline or amorphous) coat the surface of the high-melting-point fibers (or fiber components). After coating the surface of the higher-melting-point fibers (or fiber components), as the lower-melting-point material (e.g., molten and flowing lower-melting-point fibers) solidifies, the lower-melting-point material forms an adhesion with the higher-melting-point material (e.g., deformed lower-melting-point fibers) and an adhesion between the higher-melting-point materials.

[0052] In another aspect, the present invention provides a method for forming a composite material, comprising forming or providing a nonwoven fabric, such as those described and disclosed herein, and bonding a membrane layer to the nonwoven fabric. In yet another aspect, the present invention provides a composite material comprising a nonwoven fabric, such as those described and disclosed herein, and a membrane.

[0053] According to certain embodiments of the invention, the membrane is a single-layer membrane. For example, a single-layer membrane is a vapor-permeable but liquid-impermeable (VPLI) membrane. A VPLI membrane can be, for example, a monolithic membrane or a microporous membrane.

[0054] According to certain embodiments of the present invention, the membrane layer may be a multilayer membrane comprising a core layer and at least a first surface layer. The multilayer membrane may, for example, include a second surface layer, wherein the core layer is located between and adjacent to the first and second surface layers. For example, the core layer may be a microporous layer or a monolithic layer. The first surface layer, the second surface layer, or both may include a microporous layer or a monolithic layer. Alternatively or additionally, the multilayer membrane may be a vapor-permeable, liquid-impermeable (VPLI) membrane.

[0055] According to certain embodiments of the invention, the membrane layer may have a basis weight of about 5 to about 50 gsm, for example, at least about any of the following: 5, 10, 12, 15, 18, 20, 22 and 25 gsm, and / or at most about any of the following: 50, 45, 40, 35, 30, 28 and 25 gsm. Alternatively or additionally, the membrane layer is directly melt-extruded onto the nonwoven fabric. Alternatively, the membrane layer is adhesively bonded to the nonwoven fabric via an adhesive layer.

[0056] These and other modifications and variations can be made to the invention 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 exemplary and is not intended to limit the invention as further described in these appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the exemplary descriptions of the versions contained herein.

Claims

1. A method for forming a nonwoven fabric, comprising: (i) Depositing at least a first nonwoven layer comprising a first plurality of interwoven individual melt-spun fibers directly or indirectly onto a moving collection belt to provide a precursor nonwoven fiber web having an average initial transverse (CD) width and / or an average initial basis weight, The first plurality of interwoven individual melt-spun fibers may include (a) a combination of a first group of monocomponent fibers and a second group of monocomponent fibers, wherein the first group of monocomponent fibers has a first melt initiation temperature and the second group of monocomponent fibers has a second melt initiation temperature lower than the first melt initiation temperature; (b) a bicomponent fiber comprising a first component and a second component, wherein the first component has a first melt initiation temperature and the second component has a second melt initiation temperature lower than the first melt initiation temperature; and (c) a combination of a first group of bicomponent fibers and a second group of bicomponent fibers, wherein the first group of bicomponent fibers has a first higher melting point component and a first lower melting point component, and the second group of bicomponent fibers has a second higher melting point component and a second lower melting point component that begins to melt before the first lower melting point component. (ii) conveying the precursor nonwoven fiber web through a heat setting operation (HSO), the heat setting operation comprising (a) constraining the precursor nonwoven fiber web directly or indirectly within a heat setting roller gap defined between a moving collection belt and a portion of an opposing surface, such as a portion of a heat setting device, to mitigate relative movement of individually melt-spun fibers during HSO, and (b) subjecting the precursor nonwoven fiber web to a high temperature sufficient to increase the viscosity of (1) the second group of monocomponent fibers or (2) the second component of bicomponent fibers having the second melt initiation temperature or (3) the second lower melting point component of the second group of bicomponent fibers to provide an intermediate nonwoven fabric; (iii) Remove the intermediate nonwoven fabric from the HSO, wherein the intermediate nonwoven fabric has an average heat-set CD width and / or an average heat-set basis weight; as well as (iv) Consolidate the intermediate nonwoven fabric to provide a nonwoven fabric with an average final CD width and / or an average final basis weight.

2. The method of claim 1, wherein (i) the high temperature is not within about 7°C below the second melt initiation temperature or the second lower melting point component of the second group of bicomponent fibers, for example, within any of the following ranges: 6°C, 5°C, 4°C, 3°C, and 2°C below the second melt initiation temperature or the second lower melting point component of the second group of bicomponent fibers, and / or (ii) subjecting the precursor nonwoven fiber web to the high temperature includes a residence time of about 3 seconds to about 120 seconds, for example, at least about any of the following: 3, 5, 8, 10, 15, 20, 30, 40, 50, and 60 seconds, and / or at most about any of the following: 120, 100, 90, 80, 70, and 60 seconds.

3. The method of claim 1, wherein the HSO further comprises a cooling step, the cooling step reducing the temperature of the precursor nonwoven fiber web to about 20°C to about 40°C, for example at least about any one of the following: 20, 22, 25, 28 and 30°C, and / or at most about any one of the following: 40, 38, 35, 32 and 30°C, before the precursor nonwoven fiber web leaves the heat setting roll gap.

4. The method of claim 1, wherein the HSO comprises a rotating roller, wherein the heat-setting roller gap is defined by the rotating roller and the moving collection belt, and wherein the heat-setting roller gap defines a travel path of the precursor nonwoven fiber web extending about 180° to about 340° of the rotating roller, for example at least about any one of the following: 180°, 190°, 200°, 210°, 220°, 230°, 240°, 250°, 260° and 270° of the rotating roller, and / or at most about any one of the following: 340°, 330°, 320°, 310°, 300°, 290°, 280° and 270° of the rotating roller.

5. The method of claim 4, wherein the rotating drum comprises a heating section and a cooling section, wherein the precursor nonwoven fiber web is conveyed through the heating section before being conveyed through the cooling section, and wherein the heating section comprises about 70% to about 95% of the travel path, for example at least about any one of the following: 70, 75, 80 and 85%, and / or at most about any one of the following: 95, 90 and 85%, and the cooling section comprises about 5% to about 30% of the travel path, for example at least about any one of the following: 5, 10 and 15%, and / or at most about any one of the following: 30, 25, 20 and 15%.

6. The method of claim 1, wherein the HSO comprises a linear hot air bonding unit, the linear hot air bonding unit comprising a heating portion and a cooling portion, wherein the heat setting roller gap defines a travel path of the precursor nonwoven fiber web between the linear hot air bonding unit and the moving collection belt, and wherein the precursor nonwoven fiber web is conveyed through the heating portion before being conveyed through the cooling portion, and wherein the heating portion comprises about 70% to about 95% of the travel path, for example at least about any one of the following: 70, 75, 80 and 85%, and / or at most about any one of the following: 95, 90 and 85%, and the cooling portion comprises about 5% to about 30% of the travel path, for example at least about any one of the following: 5, 10 and 15%, and / or at most about any one of the following: 30, 25, 20 and 15%.

7. The method of claim 1, wherein consolidating the intermediate nonwoven fabric comprises a hot calendering operation, a hot air bonding operation, an ultrasonic bonding operation, a hot zone bonding operation, a chemical bonding operation, or any combination thereof; wherein the high temperature experienced by the first plurality of interwoven individual meltspun fibers is equal to or greater than a second melt initiation temperature or melting point associated with a second higher melting point component of the second set of bicomponent fibers, and optionally wherein the high temperature is lower than a first melt initiation temperature or melting point associated with a first higher melting point component of the first set of bicomponent fibers.

8. The method of claim 7, wherein consolidating the intermediate nonwoven fabric includes a thermocalendering operation that imparts a plurality of discrete adhesive portions defining an adhesive region, wherein the adhesive region may comprise about 3 to about 30%.

9. The method of claim 1, wherein (i) the average heat-set CD width is at least about 95% of the average initial CD width, and / or (ii) the average heat-set basis weight is at least about 95% of the average initial basis weight.

10. The method of claim 1, wherein (i) the average final CD width is at least about 95% of the average heat-set CD width, and / or (ii) the average final basis weight is at least about 95% of the average heat-set basis weight.

11. The method of claim 1, wherein (i) the average final CD width is at least about 95% of the average initial CD width, and / or (ii) the average final weight is at least about 95% of the average initial weight.

12. The method of claim 1, wherein the first plurality of individual melt-spun fibers comprises a combination of a first set of monocomponent fibers or a first set of bicomponent fibers having the first melt initiation temperature and a second set of monocomponent fibers or a first set of bicomponent fibers having a second melt initiation temperature lower than the first melt initiation temperature, wherein the first set of monocomponent fibers or the first set of bicomponent fibers defines at least one first region, and the second set of monocomponent fibers or the first set of bicomponent fibers defines at least one second region, and wherein the first plurality of individual melt-spun fibers are formed from a single polymer composition.

13. The method of claim 12, wherein during the consolidation of the intermediate nonwoven fabric, the second lower melting point component of the second group of monocomponent fibers or the second group of bicomponent fibers deforms from the initial spinning cross section and fuses with the first group of monocomponent fibers or the second group of bicomponent fibers.

14. A method for forming a composite material, comprising: (i) Forming a nonwoven fabric according to claim 1; as well as (ii) Adhere the film layer to the nonwoven fabric.

15. The method of claim 14, wherein the film layer is a single-layer film or a multilayer film, and wherein the film layer is directly melt-extruded onto the nonwoven fabric or adhesively bonded to the nonwoven fabric via an adhesive layer.

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