Method of forming multilayer nonwoven material with topographic protrusions via differential shrinkage

Abstract

A method and system for producing a nonwoven material is disclosed. The foam-formed nonwoven web includes a first layer and a second layer. The first layer shrinks relative to the second layer such that the first layer forms a plurality of protrusions on an outer surface of the first layer facing away from the second layer.

Description

Background Art

[0001] There are many different types of nonwoven materials designed to have different functions. In many embodiments, nonwoven materials are designed to have liquid handling properties. These nonwoven materials can be used for absorbent articles or for producing wiping products, tissue products, etc. Absorbent articles, also referred to as personal care products such as diapers, diaper pants, training pants, adult incontinence products and feminine care products, can include multiple substrates. For example, diapers can include absorbent structures, nonwoven materials and films. Similarly, facial tissues, wipes and wipes can also include various substrates.

[0002] In certain applications, a multilayer nonwoven material includes an acquisition layer for receiving fluids. Generally, the acquisition layer preferably has a high void volume and resistance to compression. However, conventional methods for forming nonwoven materials provide limited void volume and resistance to compression in the acquisition layer. An improved method for forming a nonwoven material with an acquisition layer having a high void volume and resistance to compression would be useful. Summary of the invention

[0003] In general, the present disclosure relates to a nonwoven material and a method for making the nonwoven material. In a foam-formed multi-layer nonwoven web such as a double-layer nonwoven web,

[0004] Adjacent layers may be at least partially structurally interconnected (e.g., fiber entanglement between adjacent layers, gradient interfaces between layers, interlayer adhesion, etc.), and

[0005] The nonwoven web may be heated to such an extent that one of the layers shrinks less than at least one other layer, which may cause a layer to deform and produce a plurality of protrusions. For example, the first layer of the nonwoven web may be at least partially (e.g., completely) cured and / or dried when the first layer is under tension. The first layer may correspond to the acquisition layer of the nonwoven web. Curing the first layer may define the structural relationship between the different first and second layers of the nonwoven web. For example, at least partially curing the first layer may define the interlayer bonding between the first and second layers. After the top layer is at least partially cured, the second layer may be cured and / or dried when the second layer is under tension. The tension in the first and / or second layers may be controlled during curing so that the contraction of the second layer deforms the first layer, thereby forming a topographic protrusion on the outer surface of the first layer. As will be described in more detail below, the exemplary aspects of the present disclosure provide many different advantages and benefits. For example, due to the topographic protrusions, the acquisition layer of the nonwoven material may advantageously have a high void volume and compression resistance.

[0006] In example aspects, various mechanisms can be utilized to form topographic protrusions via differential contraction between the first layer and the second layer. For example, the second forming layer may include fibers capable of hydrogen bonding. The contraction of the second layer may be due at least in part to capillary condensation and hydrogen bonding during drying. For another example, the second forming layer may include superabsorbent particles that partially swell during processing in the wet end of the foam forming process. The contraction of the second layer during drying may be due at least in part to the contraction of the superabsorbent particles when removing water. For another example, the second layer may include fibers or other materials that contract when heated, such as PLA staple fibers. The contraction of the second layer during heating may be due at least in part to the contraction of heat shrinkable materials. Various combinations of fibers, superabsorbents and / or heat shrinkable fibers or other materials capable of forming hydrogen bonds may also be utilized. Therefore, for example, the contraction of the second layer may be due to a combination of these mechanisms.

[0007] In an exemplary embodiment, a method for forming a nonwoven material comprises: forming a nonwoven web having a plurality of layers by foam forming; at least partially curing a first layer of the plurality of layers while the nonwoven web is under tension; after at least partially curing the first layer, curing a second layer of the plurality of layers while the nonwoven web is under tension; and relaxing the nonwoven web so that the second layer contracts and the first layer deforms to produce a plurality of protrusions at an outer surface of the first layer facing away from the second layer.

[0008] In another exemplary embodiment, the nonwoven material comprises a foam-formed nonwoven web having a first layer and a second layer. The first layer is contracted relative to the second layer so that the first layer forms a plurality of protrusions on an outer surface of the first layer facing away from the second layer.

[0009] In another exemplary embodiment, a method for forming a nonwoven material comprises: forming a nonwoven web having a plurality of layers by foam forming; heating a first layer of the plurality of layers in the nonwoven web while the nonwoven web is under tension, wherein the water content in the first layer decreases during the heating of the first layer; after heating the first layer and while the nonwoven web is under tension, heating a second layer of the plurality of layers in the nonwoven web, wherein the water content in the second layer decreases during the heating of the second layer; and after heating the second layer, relaxing the nonwoven web so that the first layer is deformed and has a plurality of protrusions at an outer surface of the first layer facing away from the second layer.

[0010] In another exemplary embodiment, a method for forming a nonwoven material comprises: forming a nonwoven web having a plurality of layers by foam forming, wherein a first layer and a second layer of the plurality of layers are at least partially interconnected; and heating the nonwoven web so that the second layer shrinks less than the first layer, and the first layer is deformed so as to produce a plurality of protrusions at an outer surface of the first layer facing away from the second layer.

[0011] Other features and aspects of the disclosure are discussed in greater detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The disclosure that makes the present disclosure comprehensive and enabling is more particularly set forth in the remainder of the specification and with reference to the accompanying drawings, in which:

[0013] Figure 1 is a schematic diagram of a system for producing a nonwoven material according to an exemplary embodiment of the present disclosure;

[0014] Figure 2 yes Figure 1 A schematic diagram of a component feed system of an example system;

[0015] Figure 3 Methods for forming nonwoven materials according to example embodiments of the present subject matter are illustrated.

[0016] Figure 4 A method for forming a nonwoven material according to another exemplary embodiment of the present subject matter is illustrated.

[0017] Figure 5 is a side elevation view of a nonwoven material according to an exemplary embodiment of the present subject matter, wherein the nonwoven material is under tension.

[0018] Figure 6 yes Figure 5 A side elevation view of an example nonwoven material of FIG. 1 , wherein the nonwoven material is in a relaxed state.

[0019] Figure 7 is a perspective view of a nonwoven material according to an example embodiment of the present subject matter.

[0020] Figure 8 yes Figure 7 A partial side elevation view of an example nonwoven material.

[0021] Fig. 9 is a perspective view of a nonwoven material according to an example embodiment of the present subject matter.

[0022] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present disclosure. DETAILED DESCRIPTION

[0023] Those skilled in the art will appreciate that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present disclosure.

[0024] Each example is given by way of illustration and is not meant to be limiting. For example, a feature illustrated or described as part of one embodiment or figure may be used in another embodiment or figure to produce yet another embodiment. It is intended that the present disclosure encompasses such modifications and variations.

[0025] When introducing elements of the present disclosure or its preferred embodiments, the articles "a", "an", "the" and "said" are intended to indicate the presence of one or more of the elements. The words "comprise", "comprising" and "having" are intended to be inclusive, meaning that there may be additional elements outside the listed elements. As used herein, the terms "first", "second", "third", etc. do not specify a specified order, but are used as a means to distinguish different events when referring to various features in the present disclosure. Without departing from the spirit and scope of the present disclosure, many modifications and variations may be made to the present disclosure. Therefore, the exemplary embodiments described herein should not be used to limit the scope of the present invention.

[0026] As used herein, the term "foam-formed product" means a product formed from a suspension comprising a mixture of solids, liquids, and dispersed gas bubbles.

[0027] As used herein, the term "foam-forming process" means a process for making a product involving a suspension comprising a mixture of solids, liquids, and dispersed gas bubbles.

[0028] As used herein, the term "foaming fluid" means any one or more known fluids that are compatible with the other components in the foam forming process. Suitable foaming fluids include, but are not limited to, water.

[0029] As used herein, the term "foam half-life" means the time that elapses until half of the initial foamed foam mass reverts to liquid water.

[0030] As used herein, the term "layer" refers to a structure that provides a material or a substrate region in the height direction of a substrate composed of similar components and structures.

[0031] As used herein, the term "nonwoven web" refers to a web having a structure of individual fibers or threads that are interlayered, but not in an identifiable manner (as in a knitted web).

[0032] As used herein, unless expressly stated otherwise, when used in connection with material composition, the terms "percent," "%," "weight percent," or "wt%" each refer to the amount of the component by weight as a percentage of the total amount, unless expressly stated otherwise.

[0033] The term "personal care absorbent article" refers herein to an article that is intended or adapted to be placed against or near the body of the wearer (i.e., adjacent to the body) to absorb and contain the various liquid, solid and semi-solid exudates discharged from the body. Examples include, but are not limited to, diapers, diaper pants, training pants, youth pant, swim pants, feminine hygiene products (including, but not limited to, menstrual pads or pants), incontinence products, medical garments, surgical pads and bandages, and the like.

[0034] As used herein, the term "superabsorbent material" refers to a water-swellable, water-insoluble organic or inorganic material, including superabsorbent polymers and superabsorbent polymer compositions that are capable of absorbing at least about 10 times their weight, or at least about 15 times their weight, or at least about 25 times their weight in an aqueous solution containing 0.9 weight percent sodium chloride under most favorable conditions.

[0035] As used herein, the term "machine direction" refers to the direction of travel of a forming surface upon which fibers are deposited during formation of a nonwoven web.

[0036] As used herein, the term "lateral" refers to a direction perpendicular to both the longitudinal and height directions (eg, perpendicular to the longitudinal and lateral directions).

[0037] As used herein, the term "pulp" refers to fibers from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, milkweed, straw, jute, hemp, and bagasse. Pulp fibers can include hardwood fibers, softwood fibers, and mixtures thereof.

[0038] As used herein, the term "average fiber length" refers to the average length of fibers, fiber bundles and / or fibrous materials determined by microscopic measurement. A sample of at least 20 randomly selected fibers is separated from a liquid suspension of fibers. The fibers are placed on a microscope slide that has been prepared to suspend the fibers in water. Coloring dyes are added to the suspended fibers to color the cellulose-containing fibers so that they can be distinguished or separated from synthetic fibers. The slide is placed under a Fisher Stereomaster II microscope--S19642 / S19643 series. 20 fibers in the sample are measured at 20X linear magnification using a 0-20 mil scale, and the average length, minimum and maximum lengths, and deviation or coefficient of variation are calculated. In some cases, the average fiber length will be calculated as the weighted average length of the fibers (e.g., fibers, fiber bundles, fibrous materials) as determined by a Kajaani fiber analyzer model FS-200, such as that available from Kajaani Oy Electronics, Kajaani, Finland. The samples are treated with an impregnation solution according to standard test procedures to ensure that no fiber bundles or fragments are present. Each sample is decomposed in hot water and diluted to approximately 0.001% suspension. When tested using the standard Kajaani fiber analysis test procedure, each test sample of approximately 50 ml to 100 ml is drawn from the diluted suspension. The weighted average fiber length can be an arithmetic mean, a length-weighted mean, or a weight-weighted mean, and can be represented by the following equation:

[0039]

[0040] in

[0041] k = maximum fiber length

[0042] x i =Fiber length

[0043] n i = Number of fibers of length xi

[0044] n = total number of fibers measured.

[0045] One characteristic of the average fiber length data measured by the Kajaani fiber analyzer is that it does not distinguish between different types of fibers. Therefore, the average length represents the average value based on the lengths of all different types (if any) of fibers in the sample.

[0046] As used herein, the term "staple fibers" refers to discontinuous fibers made from synthetic polymers or regenerated cellulose such as polypropylene, polyester, post-consumer recycled (PCR) fibers, polyester, nylon, viscose, rayon, etc., and those that are non-hydrophilic can be treated to be hydrophilic. Staple fibers can be cut fibers, etc. Staple fibers can have a cross-section that is round, bicomponent, multicomponent, shaped, hollow, etc.

[0047] Generally speaking, the present disclosure relates to methods and systems for producing nonwoven materials and nonwoven materials. In addition, the present disclosure relates to methods and systems that can produce nonwoven materials by foam forming. The nonwoven material can be a multilayer material, such as a double-layer nonwoven material. According to exemplary aspects of the present disclosure, the nonwoven material can be formed to have a three-dimensional topography on the outer surface of a layer in the layer of the nonwoven material. The three-dimensional topography can provide many advantages and benefits. The nonwoven material of the present disclosure can be used in a variety of different end-use applications. The three-dimensional topography can provide significantly improved functionality customized for a specific application.

[0048] In one exemplary aspect, for example, the three-dimensional topography can form projections that advantageously increase the void volume and increase the resistance to compression of an acquisition layer in an absorbent article, a wiping product, etc. The three-dimensional topography can also form fluid control channels that can be used to quickly intake and distribute fluids, which can provide advantages when incorporated into an absorbent article, a wiping product, etc.

[0049] In addition to the above, the three-dimensional topography can significantly improve the breathability of the material. The nonwoven material manufactured according to the exemplary aspects of the present disclosure, when included in an absorbent article, can create an optimal microclimate by allowing better air exchange at the interface between the three-dimensional topography and the wearer's skin. When incorporated into diapers, adult incontinence products, etc., the three-dimensional topography can be configured to collect and remove body feces and other body fluids to protect the skin and provide clothing that promotes better health. Since the contact area between the three-dimensional topography and the wearer's skin is reduced, the three-dimensional topography can also help to make the skin drier.

[0050] The nonwoven materials made according to the present disclosure may also provide enhanced comfort. For example, the three-dimensional topography may provide a "cushion-like" feel to the user. The three-dimensional topography may also be configured for visual appeal or as a signal to highlight some other benefits of the product to the user.

[0051] The nonwoven material manufactured according to example aspects of the present disclosure may be formed from fibers and optionally other solid materials via a foam forming process. The nonwoven material may be a multi-layer material, such as a double-layer material.

[0052] refer to Figure 1 , for exemplary purposes only, an embodiment of a method that can be used to form a nonwoven material or substrate according to an exemplary aspect of the present disclosure is shown. Figure 1 The process and system exemplified may be a foam forming process. Figure 1 As shown, the apparatus 10 is configured to form a substrate 12. In addition, the apparatus 10 can be configured as part of a foam forming process to manufacture the substrate 12 as a foam formed product. The apparatus 10 can include a first tank 14 configured to hold a first fluid supply 16. In some example embodiments, the first fluid supply 16 can be a foam. The first fluid supply 16 can include a fluid provided by a fluid supply 18. In some example embodiments, the first fluid supply 16 can include a plurality of fibers provided by a supply of fibers 20; however, in other example embodiments, the first fluid supply 16 can be free of or substantially free of a plurality of fibers. The first fluid supply 16 can also include a surfactant provided by a surfactant supply 22. In some example embodiments, the first tank 14 can include a mixer 24, which will be discussed in more detail below. The mixer 24 is operable to mix (e.g., stir) the first fluid supply 16 so as to mix the fluid, the fibers (if present), and the surfactant with air or some other gas to form a foam. The mixer 24 may also mix the foam with the fibers (if present) to create a foam suspension of the fibers, wherein the foam holds and separates the fibers to promote distribution of the fibers within the foam (e.g., as an artifact of the mixing process in the first tank 14). Uniform fiber distribution may promote desirable substrate properties, including, for example, strength and a quality visual appearance.

[0053] In certain example embodiments, the apparatus 10 may also include a second tank 26 configured to hold a second fluid supply 28. In some example embodiments, the second fluid supply 28 may be a foam. The second fluid supply 28 may include a fluid provided by a fluid supply 30 and a surfactant provided by a surfactant supply 32. In some example embodiments, the second fluid supply 28 may include a plurality of fibers in addition to or as an alternative to the fibers present in the first fluid supply 16. In some example embodiments, the second tank 26 may include a mixer 34. The mixer 34 may be operable to mix the second fluid supply 28 so as to mix the fluid and the surfactant with air or some other gas to form a foam.

[0054] For either or both of the first tank 14 and the second tank 26, the first fluid supply 16 or the second fluid supply 28 can be operated to form a foam. In some exemplary embodiments, the foaming fluid and other components can be acted to form a porous foam having an air content greater than about fifty percent (50%) by volume, and ideally an air content greater than about sixty percent (60%) by volume. In certain exemplary aspects, a highly expanded foam is formed having an air content between about sixty percent (60%) and about ninety-five percent (95%) by volume, and in other exemplary aspects, having an air content between about sixty-five percent (65%) and about eighty-five percent (85%) by volume. In certain example embodiments, the foam can be activated to introduce the foam so that the expansion ratio (the volume of air to other components in the expanded stable foam) is greater than 1:1, and in certain embodiments, the ratio of air to other components can be between about 1.1:1 and about 20:1 or between about 1.2:1 and about 15:1 or between about 1.5:1 and about 10:1 or even between about 2:1 and about 5:1.

[0055] Foam can be generated by one or more mechanisms and methods known in the art. Examples of suitable methods include, but are not limited to, such as vigorous mechanical stirring by mixers 24, 34, injection of compressed air, and the like. Mixing components by using a high shear high-speed mixer is particularly suitable for forming desired highly porous foams. Various high shear mixers are known in the art and are considered to be suitable for exemplary aspects of the present disclosure. High shear mixers typically use a tank that holds a foam precursor and / or one or more pipes through which the foam precursor is guided. High shear mixers can use a series of screens and / or rotors to process the precursor and cause vigorous mixing of components and air. In a specific exemplary embodiment, a first tank 14 and / or a second tank 26 are provided, wherein there are one or more rotors or impellers and associated stators. The rotor or impeller rotates at high speed to cause flow and shear. For example, air can be introduced into the tank at various positions, or simply inhaled by the action of mixers 24, 34. While the specific mixer design may affect the speed required to achieve the desired mixing and shearing, in certain example embodiments, suitable rotor speeds may be greater than about five hundred revolutions per minute (500 rpm), and, for example, between about one thousand revolutions per minute (1000 rpm) and about six thousand revolutions per minute (6000 rpm) or between about two thousand revolutions per minute (2000 rpm) and about four thousand revolutions per minute (4000 rpm). In certain example embodiments, relative to rotor-based high shear mixers, the mixers 24, 34 may be run with the foam until the vortex in the foam disappears or a sufficient volume increase is achieved.

[0056] In addition, it should be noted that for the first tank 14 and / or the second tank 26, the foaming process can be completed in a single foam generation step or in a continuous foam generation step. For example, in an exemplary embodiment, all components of the first fluid supply 16 in the first tank 14 (e.g., the supply of fluid 18, fiber 20 and surfactant 22) can be mixed together to form a slurry, and the foam is formed by the slurry. Alternatively, one or more separate components can be added to the foaming fluid to form an initial mixture (e.g., a dispersion or foam), and then the remaining components can be added to the initial foamed slurry, and then all components are acted to form the final foam. In this regard, the fluid 18 and the surfactant 22 can start mixing and act to form the initial foam before adding any solids. If desired, the fiber can then be added to the water / surfactant foam, and then the fiber is further acted to form the final foam. As another example alternative, the fluid 18 and fibers 20 (such as high density cellulose pulp) may be vigorously mixed at a higher consistency to form an initial dispersion, after which a foaming surfactant, additional water, and other components (such as synthetic fibers) are added to form a second mixture, which is then mixed and acted to form a foam.

[0057] The foam density of the foam forming the first fluid supply 16 in the first tank 14 and / or the foam forming the second fluid supply 28 in the second tank 26 can vary depending on the specific application and various factors, such as the fiber raw material used. In some example implementations, the foam density of the foam can be greater than about one hundred grams per liter (100 g / L), such as greater than about two hundred and fifty grams per liter (250 g / L), such as greater than about three hundred grams per liter (300 g / L). The foam density can generally be less than about eight hundred grams per liter (800 g / L), such as less than about five hundred grams per liter (500 g / L), such as less than about four hundred grams per liter (400 g / L), such as less than about three hundred and fifty grams per liter (350 g / L). In some example implementations, lower density foams may be used, with foam densities typically less than about three hundred fifty grams per liter (350 g / L), such as less than about three hundred forty grams per liter (340 g / L), such as less than about three hundred thirty grams per liter (330 g / L).

[0058] In some example embodiments, the apparatus 10 may also include a first pump 36 and a second pump 38. The first pump 36 may be in fluid communication with the first fluid supply 16 and may be configured to pump the first fluid supply 16 to transfer the first fluid supply 16. The second pump 38 may be in fluid communication with the second fluid supply 28 and may be configured to pump the second fluid supply 28 to transfer the second fluid supply 28. In some example embodiments, the first pump 36 and / or the second pump 38 may be a screw pump or a centrifugal pump, however, it is contemplated that other suitable types of pumps may be used. Additionally, as discussed further below, in some example embodiments, the apparatus may be provided with a single pump that may pump a single fluid supply into the first fluid supply 16 and the second fluid supply 28.

[0059] like Figure 1 and Figure 2 , the apparatus 10 may also optionally include a component feed system 40. For example, the component feed system 40 may be configured to feed particulate material (such as superabsorbent particles) into the fiber furnish. However, when the substrate is formed solely of fibers, the component feed system 40 may not be required, including the use of the second fluid supply 28. When present, the component feed system 40 may include a component supply area 42 for receiving a supply of a component 44, such as Figure 2 4. The component feed system 40 may further include an outlet conduit 46. The cross-sectional shape of the outlet conduit 46 may be circular, or may be configured in a rectangular form to form a slot. The component feed system 40 may further include a hopper 48. The hopper 48 may be coupled to the component supply zone 42 and may be configured to refill the supply of the component 44 to the component supply zone 42.

[0060] In some exemplary embodiments, the component feed system 40 may include a solid volumetric pump. Some examples of solid volumetric pumps that may be used herein include systems utilizing screws / auger, belts, vibrating trays, turntables, or other known systems for handling and discharging the supply of component 44. Other types of feeders may be used for the component feed system 40, such as batching feeders, such as those manufactured by Christy Machine & Conveyor, Fremont, Ohio. In some exemplary embodiments, the component feed system 40 may also be configured as a conveyor system.

[0061] The component feed system 40 may also include a fluid control system 50. The fluid control system 50 may be configured to control the entrainment of gas into the fluid supply in which the supply of component 44 is placed. In some example embodiments, the fluid control system 50 may include a housing 52. The housing 52 may form a pressurized sealed volume around the component feed system 40. In other example embodiments, the fluid control system 50 may be formed as an integral part of the structural component feed system 40 itself, such that a separate housing 52 surrounding the component feed system 40 may not be required. Figure 1 and Figure 2 As shown, in some example embodiments, the fluid control system 50 may also include a bleed hole 54 .

[0062] The supply of component 44 can be in the form of particles and / or fibers. In an exemplary embodiment described herein, the supply of component 44 can be a superabsorbent material (SAM) in the form of particles. In some exemplary embodiments, SAM can be in the form of fibers. Of course, as further described below, other types of components may also be considered for use in the apparatus 10 and method described herein. The component feed system 40 as described herein can be particularly beneficial for the supply of component 44 that is most suitable for maintaining in a dry environment, wherein minimal exposure to the fluid or foam used in the apparatus 10 and method described herein.

[0063] In some example embodiments, the apparatus 10 and methods described herein may include a first mixing joint 56 and a second mixing joint 58. In a preferred example embodiment, the first mixing joint 56 may be an ejector. The first mixing joint 56 may be in fluid communication with the outlet conduit 46 of the component feed system 40 and in fluid communication with the second fluid supply 28. The first mixing joint 56 may be configured as a coaxial ejector. The first mixing joint 56 may mix the supply of the component 44 from the component feed system 40 with the second fluid supply 28.

[0064] Reference again Figure 1In some example embodiments, the apparatus 10 may include a second mixing joint 58. The second mixing joint 58 may be configured to mix the second fluid supply 28 (including components from the supply of component 44) with the first fluid supply 16. When the second fluid supply 28 (including components from the supply of component 44) exits the discharge port 64 of the first mixing joint 56, the second fluid supply 28 may be transferred to the second mixing joint 58. The first fluid supply 16 may be delivered to the second mixing joint 58 by the first pump 36. The second mixing joint 58 may mix the first fluid supply 16 and any components of the first fluid supply 16 (e.g., fluid 18, fibers 20, surfactant 22) with the second fluid supply 28 and any components of the second fluid supply 28 (e.g., fluid 30, surfactant 32) and components from the supply of component 44 to provide a resulting slurry 76. The resulting slurry 76 may be transferred from the second mixing joint 58 to the headbox 80 through the discharge port 78 of the second mixing joint 58.

[0065] A headbox 80 may be provided to transfer the resulting slurry 76 to form the substrate 12. The headbox 80 may have a longitudinal direction 81 and a transverse direction 83. The longitudinal direction 81 may be the direction in which the resulting slurry 76 is transferred through the headbox 80. The wet slurry 76 may be deposited from the headbox 80 onto a forming surface 94 manufactured according to example aspects of the present disclosure.

[0066] exist Figure 1 In the illustrated example embodiment, the forming surface 94 is shown in a horizontal position. In alternative example embodiments, the forming surface 94 may be placed or oriented at an angle relative to the headbox 80 so that the slurry 76 moves in an upward motion once deposited onto the forming surface 94. For example, the forming surface 94 may be positioned relative to the horizontal at an angle greater than about five degrees (5°), such as greater than about ten degrees (10°), such as greater than about fifteen degrees (15°), and generally less than about fifty degrees (50°), such as less than about forty degrees (40°), such as less than about thirty degrees (30°), such as less than about twenty degrees (20°). The headbox 80 may be designed to produce a single-layer substrate, or may be used to produce a multi-layer substrate. The substrate 12 may be made according to example aspects of the present disclosure, for example, with two (2) layers, three (3) layers, four (4) layers, five (5) layers, etc. If desired, each layer may have a different fiber furnish.

[0067] Once the slurry 76 is deposited on the forming surface 94, the fluid can be removed from the suspension to form a nonwoven substrate. In this regard, the forming surface 94 can be a porous porous plate and can be made at least in part from a woven belt or a screen. The system can also include a dewatering system 96 that can be configured to remove liquid from the slurry 76 through the forming surface 94. For example, the dewatering system 96 can provide a vacuum to the slurry 76 to extract fluid from the slurry, thereby forming a consolidated substrate 12.

[0068] like Figure 1 As shown, the process may also include a drying system 98. The drying system 98 may be configured to dry the newly formed nonwoven substrate 12. Generally speaking, any suitable dryer may be incorporated into the drying system 98. For example, the drying system 98 may be a through-air dryer, one or a series of heated drums, an oven, etc. The process may also include a winding system 99, which may be configured to wind the substrate 12 into a roll after drying.

[0069] As described above, the nonwoven substrate manufactured according to the exemplary aspects of the present disclosure can be formed according to a foam forming process. The foam forming process can provide various advantages. For example, the foam forming process can more easily process longer fibers, requires less water to form a web, and can require less energy to dry the web.

[0070] When forming a nonwoven substrate according to a foam forming process, the wet slurry 76 can be a fiber foam suspension alone or in combination with other solid materials. In some exemplary embodiments, the foaming fluid can account for about eighty-five percent (85%) of the foam (by weight) to about ninety-nine to ninety-nine percent (99.99%). In some exemplary embodiments, the foaming fluid used to make the foam can account for at least about eighty-five percent (85%) of the foam (by weight). In certain exemplary embodiments, the foaming fluid can account for about ninety percent (90%) of the foam (by weight) to about ninety-nine to ninety-nine percent (99.9%). In certain other exemplary embodiments, the foaming fluid can account for about ninety-three percent (93%) to ninety-nine point five percent (99.5%) of the foam (by weight), or even about ninety-five percent (95%) to about ninety-nine percent (99%). In a preferred exemplary embodiment, the foaming fluid can be water, however, it is conceivable that other processes can utilize other foaming fluids.

[0071] As described herein, the foam forming process can utilize one or more foaming agents (such as surfactants) to form foam. Fibers and surfactants can form a stable dispersion together with the foaming liquid and any additional components, and the dispersion can basically maintain a high porosity for a longer time than the drying process. In this regard, the surfactant can be selected to provide a foam with a foam half-life of at least two minutes (2 minutes), more preferably at least five minutes (5 minutes), and most preferably at least ten minutes (10 minutes). The foam half-life can be a function of the type of surfactant, surfactant concentration, foam component / solid level and mixing ability / air content in the foam. The foaming surfactant used in the foam can be selected from one or more foaming surfactants known in the art that can provide a desired degree of foam stability. In this regard, the foaming surfactant can be selected from anionic, cationic, nonionic and amphoteric surfactants, provided that the foaming surfactant provides necessary foam stability or foam half-life alone or in combination with other components. It should be understood that more than one surfactant can be used, including different types of surfactants (as long as the surfactants are compatible) and more than one surfactant of the same type. For example, due to the compatibility between surfactants, a combination of a cationic surfactant and a nonionic surfactant or a combination of an anionic surfactant and a nonionic surfactant may be used in some exemplary embodiments. However, in some exemplary embodiments, a combination of a cationic surfactant and an anionic surfactant may not be satisfactorily combined due to the incompatibility between the surfactants.

[0072] Anionic surfactants considered suitable for use in exemplary aspects of the present disclosure include, but are not limited to, anionic sulfate surfactants, alkyl ether sulfonates, alkyl aryl sulfonates, or mixtures or combinations thereof. Examples of alkyl aryl sulfonates include, but are not limited to, alkyl benzene sulfonic acid and its salts, dialkyl benzene disulfonic acid and its salts, dialkyl benzene sulfonic acid and its salts, alkyl phenol sulfonic acid / condensed alkyl phenol sulfonic acid and its salts, or mixtures or combinations thereof. Examples of additional anionic surfactants believed to be suitable for use in exemplary aspects of the present disclosure include alkali metal sulforicinates; sulfonated glycerides of fatty acids such as sulfonated monoglyceride of coconut oleic acid; salts of sulfonated monovalent alcohol esters such as sodium oleylisethianate; metal soaps of fatty acids; amides of aminosulfonic acids such as the sodium salt of oleylmethyl taurine; sulfonated products of fatty acid nitriles such as palmitonitrile sulfonate; alkali metal alkyl sulfates such as sodium lauryl sulfate, ammonium lauryl sulfate, or triethanolamine lauryl sulfate; ether sulfates having an alkyl group of eight (8) or more carbon atoms such as sodium lauryl ether sulfate, ammonium lauryl ether sulfate, sodium alkyl aryl ether sulfate, and ammonium alkyl aryl ether sulfate; sulfates of polyoxyethylene alkyl ethers; sodium, potassium, and amine salts of alkylnaphthalenesulfonic acids. Certain phosphate surfactants, including phosphate esters such as sodium lauryl phosphate ester or those available from the Dow Chemical Company under the trade name TRITON, are also believed to be suitable for use herein. A particularly desirable anionic surfactant is sodium dodecyl sulfate (SDS).

[0073] Cationic surfactants are also considered to be suitable for use in some exemplary embodiments of manufacturing substrates together with the exemplary aspects of the present disclosure. In some exemplary embodiments, such as those including superabsorbent materials, cationic surfactants may be less preferred for use due to potential interactions between cationic surfactants and superabsorbent materials (which may be anionic). Foaming cationic surfactants include, but are not limited to, monocarbonyl ammonium salts, dicarbonyl ammonium salts, tricarbonyl ammonium salts, monocarbonyl phosphonium salts, dicarbonyl phosphonium salts, tricarbonyl phosphonium salts, carbonyl carboxyl salts, quaternary ammonium salts, imidazolines, ethoxylated amines, quaternary phospholipids, etc. Additional examples of cationic surfactants include various fatty acid amines and amides and their derivatives, and salts of fatty acid amines and amides. Examples of aliphatic fatty acid amines include dodecylamine acetate, octadecylamine acetate, and acetates of amines of tallow fatty acids; homologues of aromatic amines with fatty acids, such as dodecylaniline; fatty amides derived from aliphatic diamines, such as undecylimidazoline; fatty amides derived from aliphatic diamines, such as undecylimidazoline; fatty amides derived from disubstituted amines, such as oleylaminodiethylamine; derivatives of ethylenediamine; quaternary ammonium compounds and salts thereof, for example tallow trimethylammonium chloride, dioctadecyldimethylammonium chloride, didodecyldimethylammonium chloride, dihexadecylammonium chloride, alkyltrimethylammonium hydroxide, dioctadecyldimethylammonium hydroxide, tallow trimethylammonium hydroxide, trimethylammonium hydroxide, methylpolyoxyethylenecocoylammonium chloride, and dipalmitylhydroxyethylmethylammonium sulfate; amide derivatives of amino alcohols, such as β-hydroxyethylstearamide; and amine salts of long-chain fatty acids. Additional examples of cationic surfactants believed to be suitable for use in exemplary aspects of the present disclosure include benzalkonium chloride, benzethonium chloride, cetrimonium bromide, distearyldimethylammonium chloride, tetramethylammonium hydroxide, and the like.

[0074] Nonionic surfactants considered suitable for use in exemplary aspects of the present disclosure include, but are not limited to, condensates of ethylene oxide with long chain fatty alcohols or fatty acids, condensates of ethylene oxide with amines or amides, condensation products of ethylene oxide and propylene oxide, fatty acid alkanolamides, and fatty amine oxides. Various additional examples of nonionic surfactants include alkyl polyglycosides, stearyl alcohol, sorbitan monostearate, octyl glucoside, octaethylene glycol monododecyl ether, lauryl glucoside, cetyl alcohol, cocamide MEA, glyceryl monolaurate, polyoxyalkylene alkyl ethers (such as polyethylene glycol long chain (12-14C) alkyl ethers), polyoxyalkylene sorbitan ethers, polyoxyalkylene alkoxylated esters, polyoxyalkylene alkylphenol ethers, ethylene glycol propylene glycol copolymers, polyvinyl alcohol, alkyl polysaccharides, polyethylene glycol sorbitan monooleate, octylphenol ethylene oxide, and the like.

[0075] The foaming surfactant may be used in different amounts as needed to achieve the desired foam stability and air content in the foam. In certain exemplary embodiments, the foaming surfactant may comprise from about 0.005% to about 5% (5%) of the foam (by weight). In certain exemplary embodiments, the foaming surfactant may comprise from about 0.05% to about 3% (3%) of the foam (by weight), or even from about 0.05% to about 2% (2%) of the foam.

[0076] The fibers and / or other solid materials used to form the nonwoven substrate according to the exemplary aspects of the present disclosure may vary according to specific applications and desired results. For example, the nonwoven substrate may be formed by pulp fibers, other natural fibers such as cotton fibers, regenerated cellulose fibers, synthetic polymer fibers, binder fibers, superabsorbent particles, and mixtures thereof. For example, when producing tissue products, the nonwoven substrate may include pulp fibers greater than about ninety percent (90%) by weight. When producing wiping products, the nonwoven substrate may be made of separate pulp fibers or in combination with polymer synthetic fibers such as polyester fibers. When producing nonwoven substrates for absorbent articles, the nonwoven substrate may include superabsorbent particles combined with at least one type of fiber. At least one type of fiber may include pulp fibers, pulp fibers combined with polymer synthetic fibers, pulp fibers combined with binder fibers, pulp fibers combined with synthetic polymer fibers and binder fibers, pulp fibers combined with regenerated cellulose fibers, or any other suitable mixture.

[0077] A wide variety of cellulosic fibers are considered suitable for use herein. In some exemplary embodiments, the fibers used may be conventional papermaking fibers, such as wood pulp fibers formed by a variety of pulping processes, such as kraft pulp, sulfite pulp, bleached chemi-thermomechanical pulp (BCTMP), chemi-thermomechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), and the like. By way of example only, fibers and methods for preparing wood pulp fibers are disclosed in US4793898 to Laamanen et al., US4594130 to Chang et al., US3585104 to Kleinhart, US5595628 to Gordon et al., US5522967 to Shet, and the like. In addition, the fibers may be any high average fiber length wood pulp, low average fiber length wood pulp, or mixtures thereof. Examples of suitable high-average length pulp fibers include softwood fibers such as, but not limited to, northern softwood, southern softwood, redwood, red cedar, hemlock, pine (e.g., southern pine), spruce (e.g., black spruce), etc. Examples of suitable low-average length pulp fibers include hardwood fibers such as, but not limited to, eucalyptus, maple, birch, poplar, etc.

[0078] In addition, if desired, secondary fibers obtained from recycled materials, such as fiber pulp from sources such as newsprint, recycled cardboard, and office waste paper, can be used. In a particularly preferred exemplary embodiment, refined fibers are utilized in the tissue web so that the total amount of virgin and / or high average fiber length wood fibers (such as softwood fibers) can be reduced.

[0079] Regardless of the source of the wood pulp fibers, the wood pulp fibers may preferably have an average fiber length greater than about two tenths of a millimeter (0.2 mm) and less than about three millimeters (3 mm), such as from about thirty-five hundredths of a millimeter (0.35 mm) to about two and a half millimeters (2.5 mm), or between about half a millimeter (0.5 mm) and about two millimeters (2 mm), or even between about seven tenths of a millimeter (0.7 mm) and about one and a half millimeters (1.5 mm).

[0080] In addition, other cellulose fibers that can be used for the exemplary aspects of the present disclosure include non-wood fibers. As used herein, the term "non-wood fibers" generally refers to cellulose fibers derived from non-wood monocotyledonous or dicotyledonous plant stems. Non-limiting examples of dicotyledonous plants that can be used to produce non-wood fibers include kenaf, jute, flax, ramie and hemp. Non-limiting examples of monocotyledonous plants that can be used to produce non-wood fibers include cereal straw (wheat, rye, barley, oats, etc.), stalks (corn, cotton, sorghum, hemp, etc.), rattan (bamboo, sisal, bagasse, etc.) and grasses (miscanthus, Spanish grass, lemon, sabai, switchgrass, etc.). In other certain cases, non-wood fibers can be derived from aquatic plants such as water hyacinth, microalgae such as spirulina and large seaweed such as red algae or brown algae.

[0081] Additionally, other cellulosic fibers used to make the substrates herein may include synthetic cellulosic fiber types formed by spinning, including rayon in all its types, and other fibers derived from viscose or chemically modified cellulose, such as, for example, those available under the trade names LYOCELL and TENCEL.

[0082] In some example embodiments, non-wood and synthetic cellulosic fibers may have a fiber length greater than about two tenths of a millimeter (0.2 mm), including, for example, having an average fiber size between about half a millimeter (0.5 mm) and about thirty millimeters (30 mm), or between about seventy-five hundredths of a millimeter (0.75 mm) and about eight millimeters (8 mm), or even between about one millimeter (1 mm) and about five millimeters (5 mm).

[0083] Additional fibers that can be used in exemplary aspects of the present disclosure include synthetic polymer fibers. By way of non-limiting example, such fibers can include polyolefins, polyesters (PET), polyamides, polylactic acid, or other fiber-forming polymers. Polyolefin fibers such as polyethylene (PE) and polypropylene (PP) are particularly suitable for use in exemplary aspects of the present disclosure.

[0084] The synthetic polymer fibers may have a fiber length greater than about two tenths of a millimeter (0.2 mm), including, for example, having an average fiber size between about half a millimeter (0.5 mm) and about fifty millimeters (50 mm), or between about seventy-five millimeters (0.75) and about ten millimeters (10 mm), or between about one millimeter (1 mm) and about eight millimeters (8 mm). In an example embodiment, the synthetic polymer fibers may be staple fibers having a fiber length greater than about two millimeters (2 mm), such as greater than about three millimeters (3 mm), such as greater than about four millimeters (4 mm), and typically less than about eight millimeters (8 mm), such as less than about seven millimeters (7 mm), such as less than about six millimeters (6 mm), such as less than about five millimeters (5 mm), such as less than about four millimeters (4 mm). The size of the polymer fibers may be less than about five (5) deniers, such as less than about three (3) deniers, such as less than about two (2) deniers, and greater than about half (0.5) deniers, such as greater than about one (1) denier.

[0085] In an exemplary embodiment, the fiber furnish may include a binder material that, once activated, consolidates the substrate. For example, the fiber furnish may include binder fibers that bond to adjacent fibers when heated, such as during drying of the substrate.

[0086] Binder materials that can be used in the exemplary aspects of the present disclosure may include, but are not limited to, thermoplastic binder fibers, such as PET / PE bicomponent binder fibers and water-compatible adhesives, such as latex. In some exemplary embodiments, the binder material used herein may be in powder form, such as, for example, thermoplastic PE powder. Importantly, the binder may include a binder that is insoluble in water on a dry substrate. In certain exemplary embodiments, the latex used in the exemplary aspects of the present disclosure may be cationic or anionic to facilitate application and adhesion to cellulose fibers that can be used herein. For example, latex that is considered to be applicable includes, but is not limited to, anionic styrene-butadiene copolymers, polyvinyl acetate homopolymers, vinyl acetate-ethylene copolymers, vinyl acetate-acrylic acid copolymers, ethylene-vinyl chloride copolymers, ethylene-vinyl chloride-vinyl acetate terpolymers, acrylic polyvinyl chloride polymers, acrylic acid polymers, nitrile polymers, and other suitable anionic latex polymers known in the art. Examples of such latexes are described in US4785030 granted to Hager, US6462159 granted to Hamada, US6752905 granted to Chuang et al., etc. Examples of suitable thermoplastic binder fibers include, but are not limited to, monocomponent and multicomponent fibers of thermoplastic polymers such as polyethylene having at least one relatively low melting point. In certain exemplary embodiments, polyethylene / polypropylene sheath / core staple fibers may be used. The binder fibers may have lengths consistent with those described above for synthetic polymer fibers.

[0087] The binder in liquid form (such as a latex emulsion) may comprise from about zero percent (0%) to about ten percent (10%) by weight of the substrate. When used, the binder fiber may be added to the other components in proportion to obtain the desired fiber ratio and structure. For example, in some exemplary embodiments, the binder fiber may comprise from about zero percent (0%) to about fifty percent (50%) by weight of the total fiber, and more preferably, in some exemplary embodiments, from about five percent (5%) to about forty percent (40%) by weight of the total fiber.

[0088] An additional additive that can be added during the formation of the substrate 12 as described herein can be a superabsorbent material (SAM). SAM is generally provided in particulate form and can include polymers of unsaturated carboxylic acids or their derivatives in certain exemplary aspects. These polymers are generally made water-insoluble but water-swellable by crosslinking the polymer with a difunctional or multifunctional internal crosslinking agent. These internally crosslinked polymers are at least partially neutralized and generally contain pendant anionic carboxyl groups on the polymer backbone, which enable the polymer to absorb aqueous fluids, such as body fluids. Generally, the SAM particles are post-treated to crosslink the pendant anionic carboxyl groups on the surface of the particles. SAM is manufactured by known polymerization techniques, ideally by gel polymerization in aqueous solution. The product of this polymerization process is an aqueous polymer gel, i.e., a SAM hydrogel that is reduced in size to small particles by mechanical force, and then dried using drying procedures and equipment known in the art. After the drying process, the resulting SAM particles are crushed to a desired particle size. Examples of superabsorbent materials include, but are not limited to, those described in US7396584 to Azad et al., US7935860 to Dodge et al., US2005 / 5245393 to Azad et al., US2014 / 09606 to Bergam et al., WO2008 / 027488 to Chang et al., and the like. In addition, to aid processing, the SAM may be treated so that the material is temporarily non-absorbent during the formation of the foam and the formation of the highly expanded foam. For example, in one exemplary aspect, the SAM may be treated with a water-soluble protective coating having a selected dissolution rate so that the SAM is substantially not exposed to the aqueous carrier until the highly expanded foam has been formed and the drying operation has begun. Alternatively, to prevent or limit premature expansion during processing, the SAM may be introduced into the process at low temperatures.

[0089] Superabsorbent material can be incorporated into the nonwoven substrate generally in an amount of about one percent (1%) to about ninety-five (95%) by weight, including all increments of one percent (1%) by weight therebetween. For example, superabsorbent material can be present in an amount greater than about ten percent (10%) by weight, such as greater than about twenty percent (20%) by weight, such as greater than about thirty percent (30%) by weight, such as greater than about forty percent (40%) by weight, such as less than about fifty percent (50%) by weight, and generally less than about sixty-five percent (65%) by weight, such as less than about fifty-five percent (55%) by weight, such as less than about forty-five percent (45%) by weight in the substrate.

[0090] Other additives that may be incorporated into the nonwoven substrate include wet strength additives, permanent wet strength additives, temporary wet strength additives, dry strength additives, and the like.

[0091] Other additional components that may also be added to the substrate include one or more pigments, opacifiers, antimicrobial agents, pH adjusters, skin benefit agents, odor absorbers, fragrances, heat-expandable microspheres, foam particles (such as crushed foam particles), etc., as needed to impart or improve one or more physical or aesthetic properties. In certain exemplary embodiments, the substrate may include skin benefit agents such as antioxidants, astringents, conditioners, emollients, deodorants, topical analgesics, film formers, humectants, hydrotropes, pH adjusters, surface modifiers, skin care agents, etc. When employed, the miscellaneous components desirably include less than about two percent (2%) (by weight) of the substrate.

[0092] Figure 3 A method 200 for forming a nonwoven material according to an exemplary embodiment of the present subject matter is illustrated. The method 200 can be performed in the apparatus 10 as part of a foam forming process of a nonwoven material (such as a substrate 12). Therefore, the method 200 is described in more detail below in the context of the apparatus 10. However, it should be understood that in alternative exemplary embodiments, the method 200 can be performed or implemented in any suitable foam forming system. Using the method 200, a nonwoven material (such as a substrate 12) can be formed with a three-dimensional topography, for example, on the outer surface of one of the layers of the substrate 12.

[0093] At 210, the substrate 12 may be formed with a plurality of layers. For example, at 210, the headbox 80 may deposit the plurality of slurries 76 onto the forming surface 94 to form the substrate 12 having a plurality of layers, such as two (2), three (3), four (4), five (5), or more layers. At 210, foaming the substrate 12 may include depositing the first foam and the second foam onto the forming surface 94 using the headbox 80.

[0094] In certain exemplary embodiments, each layer in substrate 12 may have a different fiber furnish. Figure 5 and Figure 6As shown, the substrate 12 may include a first layer 410 and a second layer 420. The first layer 410 may be configured as a collection layer, and the second layer 420 may be configured as an absorbent layer. Thus, the first layer 410 may be configured to collect and move feces and other body fluids away from the body, such as toward or move to the second layer 420, which is configured to collect feces and other body fluids therein. In certain example embodiments, the first layer 410 and the second layer 420 may have different fiber formulations. For example, the second layer 420 may include, for example, a highly absorbent material in an amount of about one percent (1%) to about ninety-five percent (95%) by weight. Conversely, the first layer 410 may be substantially free of superabsorbent material. For another example, the second layer 420 may be substantially free of PET fibers, while the first layer 410 includes PET fibers. Thus, for example, a first foam may include water and a plurality of first binder fibers, such as PET / PE fibers (e.g., PET as a core and PE as a sheath), and a second foam may include water and a plurality of second binder fibers, such as PET / PE fibers (e.g., having a different fiber diameter and / or length than the PET / PE fibers of the first binder fibers). The difference in fiber furnish between the first layer 410 and the second layer 420 may facilitate differential shrinkage between the first layer 410 and the second layer 420, as discussed in more detail below.

[0095] In certain example embodiments, the basis weight 410 of the first layer may be selected to help form a three-dimensional topography on the first layer 410. For example, the basis weight of the first layer 410 may generally be greater than about 40 gsm, such as greater than about 50 gsm, such as greater than about 60 gsm, such as greater than about 70 gsm, such as greater than about 80 gsm, such as greater than about 90 gsm, such as greater than about 100 gsm. The basis weight of the first layer 410 may generally be less than about 200 gsm, such as less than about 150 gsm, such as less than about 100 gsm.

[0096] like Figure 5 and Figure 6As shown, the first layer 410 and the second layer 420 may also have different dimensional characteristics. For example, each of the first layer 410 and the second layer 420 may have a corresponding thickness, for example, perpendicular to both the longitudinal direction 81 and the transverse direction 83. In addition, the first layer 410 may have a thickness T1, and the second layer 420 may have a thickness T2. The thickness T2 of the second layer 420 may be different from the thickness T1 of the first layer 410. For example, in certain example embodiments, the thickness T2 of the second layer 420 may be greater than the thickness T1 of the first layer 410. For example, the thickness T2 of the second layer 420 may be not less than one and a half times (1.5X) the thickness T1 of the first layer 410, such as not less than two times (2X), such as not less than three times (3X), such as not less than five times (5X), such as not less than ten times (10X). Therefore, for example, the thickness T2 of the second layer 420 may be significantly greater than the thickness T1 of the first layer 410. Such relative size differences between the first layer 410 and the second layer 420 may facilitate differential shrinkage between the first layer 410 and the second layer 420, as discussed in more detail below.

[0097] At 220, the substrate 12 may be cured such that the second layer 420 shrinks less than the first layer 410. Such differential shrinkage may deform the first layer 410 to produce a plurality of protrusions 412 at an outer surface 414 of the first layer 410, for example, facing away from the second layer 420. For example, at 220, the drying system 98 may be configured to at least partially dry the substrate 12. In certain example embodiments, the first layer 410 may be exposed to or placed in contact with a heated roller, oven, or the like such that the first layer 410 is cured or dried faster than the second layer 420 during 220. Thus, for example, the first layer 410 may face a heating element within an oven, contact a surface of a heated roller, or be exposed to a heated air flow throughout the drying system such that the first layer 410 shrinks to a greater degree than the second layer 420 at 220. The relative size difference between the first layer 410 and the second layer 420 may also facilitate the differential shrinkage between the first layer 410 and the second layer 420. In addition, when the second layer 420 is thicker than the first layer 410, the first layer 410 can cure or dry faster than the second layer 420 in the drying system 98 during 220. The difference in fiber furnish between the first layer 410 and the second layer 420 can also facilitate differential shrinkage between the first layer 410 and the second layer 420. In addition, when the second layer 420 includes superabsorbent material and the first layer 410 is substantially free of superabsorbent material, the first layer 410 can cure or dry faster than the second layer 420 in the drying system 98 at 220. Therefore, the relative size difference between the first layer 410 and the second layer 420 and / or the difference in fiber furnish between the first layer 410 and the second layer 420 can facilitate differential shrinkage between the first layer 410 and the second layer 420 at 220.

[0098] It should be understood that, in addition to at least partial solidification of the first layer, the material selection between the first layer and the second layer may also produce differential contraction between the two layers. For example, PET fibers are incorporated into the second layer 420, which may cause the second layer 420 to shrink more significantly than the first layer 410 (e.g., without PLA fibers) during drying and curing, so that the tension force in the nonwoven material can be reduced to cause a small local buckling of the first layer 410, thereby forming an elastic protrusion on the first layer 410. For example, the second layer 420 may include fibers capable of hydrogen bonding. In such exemplary embodiments, the differential contraction between the first layer 410 and the second layer 420 may be due at least in part to capillary condensation and hydrogen bonding during drying. In another exemplary embodiment, the second layer 420 may include superabsorbent particles that partially swell during processing in the wet end of the foam forming process. In such exemplary embodiments, the differential contraction between the first layer 410 and the second layer 420 may be due at least in part to the contraction of superabsorbent particles when removing water. In another example embodiment, the second layer 420 may include fibers or other materials that shrink when heated, such as PLA staple fibers. In such example embodiments, the differential shrinkage between the first layer 410 and the second layer 420 during heating may be due at least in part to shrinkage of the heat-shrinkable material. Any suitable combination of the above mechanisms may also be used to provide differential shrinkage between the first layer 410 and the second layer 420.

[0099] As a specific example, heat-shrinkable bi-component fibers (such as PLA / co-PLA fibers commercially available from Trevira under the trade name T-450) are capable of shrinking at least 30% of their original length under heating. When used as a binder fiber in the second layer 420, both the first layer 410 and the second layer 420 can be dried and cured at a temperature below the shrinkage temperature of the T-450 bi-component fibers. Once formed, the multi-layer nonwoven material can be exposed to a temperature close to or slightly above the curing temperature of the T-450 bi-component fibers to trigger the shrinkage of the second layer 420, thereby obtaining the protrusions 412 on the outer surface 414 of the first layer 410. Other materials that can shrink and can be triggered by temperature or other mechanisms can also be used to form the protrusions 412.

[0100] During differential contraction between the first layer 410 and the second layer 420, small sections of the first layer 410 may locally buckle to form protrusions 412. The three-dimensional topography provided by the protrusions 412 may advantageously increase the void volume and increase the resistance to compression of the first layer 410. Thus, due to the protrusions 412 formed on the first layer 410 by differential contraction between the first layer 410 and the second layer 420 during the method 200, the first layer 410 may be configured for use as an acquisition layer in an absorbent article, a wiping product, and the like. Figure 7 and Figure 8An example three-dimensional topography is illustrated provided by protrusions 412. As shown, protrusions 412 may be circular domes formed by first layer 410, for example, under relatively low tension. Fig. 9 Another example three-dimensional topography provided by protrusions 412 is illustrated. As shown, protrusions 412 may be circular corrugations, for example, formed under relatively high tension. The corrugations may be elongated in the longitudinal direction 81 on the first layer 410.

[0101] Each of the protrusions 412 may have, for example, a height perpendicular to the longitudinal direction 81 and the transverse direction 83. The height of the protrusion 412 may generally be greater than about half a millimeter (0.5 mm), such as greater than about one millimeter (1 mm), such as greater than about one and a half millimeters (1.5 mm), such as greater than about two millimeters (2 mm), such as greater than about five millimeters (5 mm). The height of the protrusion 412 may generally be less than about fifteen millimeters (15 mm), such as less than about ten millimeters (10 mm), such as less than about seven millimeters (7 mm), such as less than about five millimeters (5 mm), such as less than about three millimeters (3 mm). It should be understood that the above-mentioned height may correspond to the average height of the protrusions 412 on the outer surface 414, and the individual heights of the protrusions 412 may vary (e.g., be less than or greater than) the above-mentioned values.

[0102] Figure 4 A method 300 for forming a nonwoven material according to an exemplary embodiment of the present subject matter is illustrated. The method 300 can be performed in the apparatus 10 as part of a foam forming process of a nonwoven material (such as a substrate 12). Therefore, the method 300 is described in more detail below in the context of the apparatus 10. However, it should be understood that in alternative exemplary embodiments, the method 300 can be performed or implemented in any suitable foam forming system. Using the method 300, a nonwoven material (such as a substrate 12) can be formed with a three-dimensional topography, for example, on the outer surface of one of the layers of the substrate 12.

[0103] At 310, the substrate 12 may be formed with a plurality of layers. For example, at 310, the headbox 80 may deposit a plurality of slurries 76 onto the forming surface 94 to form a substrate 12 having a plurality of layers, such as two (2), three (3), four (4), five (5), or more layers. At 310, foaming the substrate 12 may include depositing a first foam and a second foam onto the forming surface 94 using the headbox 80.

[0104] In certain exemplary embodiments, each layer in substrate 12 may have a different fiber furnish. Figure 5 and Figure 6As shown, the substrate 12 may include a first layer 410 and a second layer 420. The first layer 410 may be configured as a collection layer, and the second layer 420 may be configured as an absorbent layer. Thus, the first layer 410 may be configured to collect and move away from body feces and other body fluids, such as toward or move to the second layer 420, which is configured to collect feces and other body fluids therein. In certain example embodiments, the first layer 410 and the second layer 420 may have different fiber furnishes. For example, the second layer 420 may include, for example, a superabsorbent material in an amount of about one percent (1%) to about seventy percent (70%) by weight. Conversely, the first layer 410 may be substantially free of superabsorbent material. For another example, the second layer 420 may include PET fibers, and the first layer 410 may be substantially free of PET fibers. In certain example embodiments, for example, the first foam may include water and a plurality of first binder fibers, such as PE fibers, and the second foam may include water and a plurality of second binder fibers, such as PET fibers. The difference in fiber furnish between the first layer 410 and the second layer 420 may facilitate differential shrinkage between the first layer 410 and the second layer 420, as discussed in more detail below.

[0105] In certain example embodiments, the basis weight 410 of the first layer may be selected to help form a three-dimensional topography on the first layer 410. For example, the basis weight of the first layer 410 may generally be greater than about 40 gsm, such as greater than about 50 gsm, such as greater than about 60 gsm, such as greater than about 70 gsm, such as greater than about 80 gsm, such as greater than about 90 gsm, such as greater than about 100 gsm. The basis weight of the first layer 410 may generally be less than about 200 gsm, such as less than about 150 gsm, such as less than about 100 gsm.

[0106] like Figure 5 and Figure 6As shown, the first layer 410 and the second layer 420 may also have different dimensional characteristics. For example, each of the first layer 410 and the second layer 420 may have a corresponding thickness, for example, perpendicular to both the longitudinal direction 81 and the transverse direction 83. In addition, the first layer 410 may have a thickness T1, and the second layer 420 may have a thickness T2. The thickness T2 of the second layer 420 may be different from the thickness T1 of the first layer 410. For example, in certain example embodiments, the thickness T2 of the second layer 420 may be greater than the thickness T1 of the first layer 410. For example, the thickness T2 of the second layer 420 may be not less than one and a half times (1.5X) the thickness T1 of the first layer 410, such as not less than two times (2X), such as not less than three times (3X), such as not less than five times (5X), such as not less than ten times (10X). Therefore, for example, the thickness T2 of the second layer 420 may be significantly greater than the thickness T1 of the first layer 410. Such relative size differences between the first layer 410 and the second layer 420 may facilitate differential shrinkage between the first layer 410 and the second layer 420, as discussed in more detail below.

[0107] At 320, the first layer 410 may be at least partially cured while the substrate 12 is under tension. For example, at 320, the drying system 98 may be configured to at least partially dry the first layer 410. Thus, at 320, during the curing of the first layer 410, the water content of the first layer 410 may be reduced. In certain example embodiments, the first layer 410 may be exposed to or placed in contact with a heated roller, oven, or the like, such that the first layer 410 cures or dries faster than the second layer 420. Thus, for example, the first layer 410 may face a heating element within an oven, contact a surface of a heated roller, or be exposed to a stream of heated air throughout the drying system such that the curing or drying rate of the first layer 410 is greater than the curing or drying rate of the second layer 420. The relative size difference between the first layer 410 and the second layer 420 may also facilitate the first layer 410 to cure or dry faster than the second layer 420. In addition, when the second layer 420 is thicker than the first layer 410, the first layer 410 may cure or dry faster than the second layer 420 in the drying system 98. The difference in fiber furnish between the first layer 410 and the second layer 420 may also facilitate the first layer 410 to cure or dry faster than the second layer 420. In addition, when the second layer 420 includes superabsorbent material and the first layer 410 is substantially free of superabsorbent material, the first layer 410 may cure or dry faster than the second layer 420 in the drying system 98. Thus, at 320, the relative size difference between the first layer 410 and the second layer 420 and / or the difference in fiber furnish between the first layer 410 and the second layer 420 may facilitate the curing of the first layer 410, for example, while the second layer 420 remains substantially uncured and / or undried. Thus, after curing the first layer 410 at 320, the water content in the second layer 420 may be greater than the water content in the first layer 410.

[0108] In certain example embodiments, at 320, portions of the first layer 410 may be cured while the substrate 12 is under tension. Thus, for example, the curing or drying rate of the first layer 410 at a first portion of the first layer 410 may be different than the curing or drying rate of the first layer 410 at a second portion of the first layer 410. Furthermore, at 320, the curing or drying pattern of the first layer 410 may be shaped or selected to control the differential shrinkage between the first layer 410 and the second layer 420, thereby controlling the three-dimensional topography provided by the protrusions 412.

[0109] At 330, after at least partially curing the first layer 410 at 320, the second layer 420 can be cured while the substrate 12 is under tension. For example, at 330, the drying system 98 can be configured to dry the second layer 420. In certain example embodiments, the second layer 420 can be exposed to or placed in contact with a heated roller, oven, or the like so that the second layer 420 is cured or dried. Thus, for example, the second layer 420 can face a heating element within an oven, contact a surface of a heated roller, or be exposed to a stream of heated air throughout the drying system.

[0110] As can be seen above, the first layer 410 is at least partially cured at 320, and then the second layer 420 is subsequently cured at 330. By first at least partially curing the first layer 410, the relationship between the first layer 410 and the second layer 420 can be fixed at least in the region of the substrate 12. In addition, at least partially curing the first layer 410 can define the interlayer adhesion between the first layer 410 and the second layer 420 before subsequently curing the second layer 420.

[0111] At 340, the substrate 12 may be relaxed. During the relaxation of the substrate 12 at 340, the second layer 420 may contract and the first layer 410 may deform to create a plurality of protrusions 412 at an outer surface 414 of the first layer 410, for example, facing away from the second layer 420. Figure 5 , the substrate 12 is shown as being under tension. As described above, during the curing of the first layer 410 and the second layer 420 at 310 and 320, the substrate 12 can be under tension. Conversely, Figure 6 , where a protrusion 412 is formed at the first layer 410 due to differential contraction between the first layer 410 and the second layer 420 when the substrate is relaxed at 340. During the curing of the second layer 420 at 330, the substrate 12 may be at least partially relaxed at 340. As another example, the relaxing of the substrate 12 at 340 may be performed after the second layer 420 is at least partially cured at 330.

[0112] During relaxation of the substrate 12 while the second layer 420 is solidified, small sections of the first layer 410 may locally buckle to form protrusions 412. The three-dimensional topography provided by the protrusions 412 may advantageously increase the void volume and increase the resistance to compression of the first layer 410. Thus, due to the protrusions 412 formed on the first layer 410 by differential contraction between the first layer 410 and the second layer 420 during the method 300, the first layer 410 may be configured for use as an acquisition layer in an absorbent article, a wipe product, and the like. Figure 7 and Figure 8 An example three-dimensional topography is illustrated provided by protrusions 412. As shown, protrusions 412 may be circular domes formed by first layer 410, for example, under relatively low tension. Fig. 9 Another example three-dimensional topography provided by protrusions 412 is illustrated. As shown, protrusions 412 may be circular corrugations, for example, formed under relatively high tension. The corrugations may be elongated in the longitudinal direction 81 on the first layer 410.

[0113] Each of the protrusions 412 may have, for example, a height perpendicular to the longitudinal direction 81 and the transverse direction 83. The height of the protrusion 412 may generally be greater than about half a millimeter (0.5 mm), such as greater than about one millimeter (1 mm), such as greater than about one and a half millimeters (1.5 mm), such as greater than about two millimeters (2 mm), such as greater than about five millimeters (5 mm). The height of the protrusion 412 may generally be less than about fifteen millimeters (15 mm), such as less than about ten millimeters (10 mm), such as less than about seven millimeters (7 mm), such as less than about five millimeters (5 mm), such as less than about three millimeters (3 mm). It should be understood that the above-mentioned height may correspond to the average height of the protrusions 412 on the outer surface 414, and the individual heights of the protrusions 412 may vary (e.g., be less than or greater than) the above-mentioned values.

[0114] As can be seen from the above, the present subject matter can advantageously provide an elastic layer with high void volume on a nonwoven material. Such layers can be particularly suitable for use as a collection layer in a diaper or wipe. Generally speaking, the exemplary aspects of the present subject matter use a combination of material selection and paired drying or curing processes to control interlayer bonding and contraction between two layers of nonwoven materials to produce a three-dimensional topography in one layer of the layer. Therefore, for example, during the forming period when the nonwoven material is under tension, the top layer of a multilayer (e.g., double-layer) nonwoven material can be fully cured or cured at a target portion so that the relationship between the top layer and the second layer below is fixed in at least some regions. The second layer can then be cured and dried while controlling the tension in the second layer to control the contraction of the nonwoven material caused by the drying of the second layer. When the second layer is dry, the second layer will contract, and reducing the tension in the nonwoven material can cause a small local buckling of the first layer to form an elastic protrusion on the first layer. Due to the dome shape of the protrusion, the protrusion advantageously increases the void volume of the first layer and also increases elasticity. Controlling the bonding points in the interlayer bonding can also adjust and / or optimize the three-dimensional topography (such as local buckling) to obtain the rigidity and fluid handling characteristics of the nonwoven material. Therefore, for example, the shape and / or distribution of the elastic protrusions can be controlled by the bonding points in the interlayer bonding between the first layer and the second layer in the nonwoven material. In some exemplary aspects, the overall structural rigidity of the nonwoven material can be advantageously controlled due to the formation of the three-dimensional topography without adding additional raw materials that will increase the overall rigidity.

[0115] The present disclosure may be better understood by reference to the following examples.

[0116] Example

[0117] The following examples were produced in accordance with the present disclosure.

[0118] In Example 1, a two-layer nonwoven substrate is formed on a forming surface. The top layer of the nonwoven substrate is about 35% by weight of bicomponent binder fibers and 65% PET staple fibers, with a basis weight of about 40 gsm, and the bottom layer of the nonwoven substrate is about 30% by weight of bicomponent binder fibers and 40% crosslinked pulp fibers (substantially incapable of hydrogen bonding) and about 30% by weight of PET fibers, with a basis weight of about 75 gsm for the second layer of fibers. The second layer also includes superabsorbent particles with a basis weight of about 400 gsm. The nonwoven substrate is dried in two passes with a total length of 14 feet, a running speed of 6 feet / minute, a residence time of 120 seconds, a temperature of 270°F for the first pass, and a temperature of 220°F for the second pass. The estimated shrinkage of the nonwoven substrate is 5%.

[0119] In Example 2, a two-layer nonwoven substrate is formed on a forming surface. The top layer of the nonwoven substrate is about 20% by weight of bicomponent binder fibers and 80% of PET staple fibers, with a basis weight of about 40 gsm, and the bottom layer of the nonwoven substrate is about 40% by weight of bicomponent binder fibers, 10% of PET fibers and 50% of NBSK wood pulp (capable of forming hydrogen bonds), with a basis weight of about 20 gsm for the second layer of fibers. The second layer also includes superabsorbent particles with a basis weight of about 345 gsm. The nonwoven substrate is dried in one pass with a total length of 7 feet, a running speed of 3 feet / minute, a residence time of 120 seconds, and a temperature of 294°F. The estimated shrinkage of the nonwoven substrate is 29%.

[0120] In Example 3, a two-layer nonwoven substrate is formed on a forming surface. The top layer of the nonwoven substrate is about 20% by weight of bicomponent binder fibers and 80% of PET staple fibers, with a basis weight of about 60 gsm, and the bottom layer of the nonwoven substrate is about 40% by weight of bicomponent binder fibers, 10% of PET fibers and 50% of NBSK wood pulp (capable of forming hydrogen bonds), with a basis weight of about 20 gsm for the second layer of fibers. The second layer also includes superabsorbent particles with a basis weight of about 400 gsm. The nonwoven substrate is dried in one pass with a total length of 7 feet, a running speed of 3 feet / minute, a residence time of 120 seconds, and a temperature of 294°F. The estimated shrinkage of the nonwoven substrate is 31%.

[0121] In the third example nonwoven material, a machine direction oriented three-dimensional topography is formed on the top layer of the nonwoven material. It is observed that the machine direction oriented three-dimensional topography depends on sufficient shrinkage of the second layer (mainly in the cross direction due to the large machine direction tension) and also depends on sufficient basis weight in the first layer.

[0122] All documents cited in the specific embodiments are, in relevant parts, incorporated herein by reference; the citation of any document should not be construed as an admission that it is prior art with respect to the present invention. In the event that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall prevail.

[0123] These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art without departing from the spirit and scope of the present invention described more specifically in the appended claims. In addition, it should be understood that the aspects of the various embodiments may be interchangeable in whole or in part. In addition, it will be appreciated by those of ordinary skill in the art that the above description is by way of example only and is not intended to limit the present invention further described in such appended claims.

[0124] Example Implementation

[0125] First exemplary embodiment: A method for forming a nonwoven material, comprising: forming a nonwoven web having a plurality of layers by foam forming; at least partially curing a first layer of the plurality of layers while the nonwoven web is under tension; after at least partially curing the first layer, curing a second layer of the plurality of layers while the nonwoven web is under tension; and relaxing the nonwoven web so that the second layer contracts and the first layer deforms to produce a plurality of protrusions at an outer surface of the first layer facing away from the second layer.

[0126] Second exemplary embodiment: A method as described in the first exemplary embodiment, wherein forming the nonwoven web by foam forming includes depositing a first foam and a second foam onto a forming surface, wherein the first foam includes water and a plurality of first binder fibers, and the second foam includes water and a plurality of second binder fibers.

[0127] Third example embodiment: The method of the first example embodiment or the second example embodiment, wherein the first layer comprises a plurality of first binder fibers, and the second layer comprises a plurality of second binder fibers and a plurality of superabsorbent particles.

[0128] Fourth example embodiment: The method as described in any one of the first to third example embodiments, wherein after said curing of said first layer, the water content in said second layer is greater than the water content in said first layer.

[0129] Fifth example embodiment: The method of any one of the first to fourth example embodiments, wherein the first layer comprises a plurality of first binder fibers, the second layer comprises a plurality of second binder fibers, and the second binder fibers are different from the first binder fibers.

[0130] Sixth example embodiment: The method of the fifth example embodiment, wherein the second binder fibers include PET fibers.

[0131] Seventh example embodiment: The method as described in any one of the first to sixth example embodiments, wherein the protrusions include a plurality of circular corrugations.

[0132] Eighth example embodiment: The method of any one of the first to seventh example embodiments, wherein the void volume of the first layer increases as the nonwoven web relaxes.

[0133] Ninth example embodiment: The method as described in any one of the first to eighth example embodiments, wherein during the curing of the first layer, the first layer is at least partially adhered to the second layer.

[0134] Tenth example embodiment: The method as described in any one of the first to ninth example embodiments, wherein the thickness of the second layer is greater than the thickness of the first layer.

[0135] Eleventh exemplary embodiment: A method as described in any one of the first exemplary embodiment to the tenth exemplary embodiment, wherein: at least partially curing the first layer includes heating the first layer, and the water content in the first layer decreases during the heating of the first layer; and curing the second layer includes heating the second layer, and the water content in the second layer decreases during the heating of the second layer.

[0136] Twelfth Example Embodiment: The method of any one of the first to tenth example embodiments, wherein the nonwoven web is a double-layer nonwoven web, and the plurality of layers includes only the first layer and the second layer.

[0137] Thirteenth Example Embodiment: The method of any one of the first to tenth example embodiments, wherein at least partially curing the first layer comprises curing a first portion of the first layer at a different rate than a second portion of the first layer.

[0138] Fourteenth exemplary embodiment: A nonwoven article comprising a nonwoven material manufactured according to the method of any one of the first to eleventh exemplary embodiments.

[0139] Fifteenth exemplary embodiment: A nonwoven material comprises: a foam-formed nonwoven web having a first layer and a second layer, wherein the first layer shrinks relative to the second layer so that the first layer forms a plurality of protrusions at an outer surface of the first layer facing away from the second layer.

[0140] Sixteenth exemplary embodiment: The nonwoven material of the fifteenth exemplary embodiment, wherein the first layer comprises a first plurality of binder fibers, and the second layer comprises a second plurality of binder fibers and a plurality of superabsorbent particles.

[0141] Seventeenth exemplary embodiment: The nonwoven material of the fifteenth exemplary embodiment or the sixteenth exemplary embodiment, wherein the first layer comprises a plurality of first binder fibers, the second layer comprises a plurality of second binder fibers, and the second binder fibers are different from the first binder fibers.

[0142] Eighteenth exemplary embodiment: The nonwoven material of any one of the fifteenth to seventeenth exemplary embodiments, wherein the second binder fibers include PET fibers.

[0143] Nineteenth exemplary embodiment: The nonwoven material of any one of the fifteenth to seventeenth exemplary embodiments, wherein the projections comprise a plurality of circular corrugations.

[0144] Twentieth exemplary embodiment: The nonwoven material of any one of the fifteenth to nineteenth exemplary embodiments, wherein the thickness of the second layer is greater than the thickness of the first layer.

[0145] Twenty-first exemplary embodiment: An absorbent article comprising the nonwoven material as described in any one of the fifteenth to twentieth exemplary embodiments, wherein when the absorbent article is worn by a wearer of the absorbent article, the outer surface of the first layer faces the wearer.

[0146] Twenty-second exemplary embodiment: A method for forming a nonwoven material, comprising: forming a nonwoven web having multiple layers by foam forming; heating a first layer of the multiple layers in the nonwoven web while the nonwoven web is under tension, wherein the water content in the first layer decreases during the heating of the first layer; after heating the first layer and while the nonwoven web is under tension, heating a second layer of the multiple layers in the nonwoven web, wherein the water content in the second layer decreases during the heating of the second layer; and while heating the second layer, relaxing the nonwoven web so that the first layer is deformed and has multiple protrusions on the outer surface of the first layer facing away from the second layer.

[0147] Twenty-third exemplary embodiment: A method for forming a nonwoven material, comprising: forming a nonwoven web having multiple layers by foam forming, wherein a first layer and a second layer of the multiple layers are at least partially interconnected; and heating the nonwoven web so that the second layer shrinks less than the first layer, and the first layer is deformed to produce multiple protrusions on the outer surface of the first layer facing away from the second layer.

[0148] Twenty-fourth exemplary embodiment: A method as described in the twenty-third exemplary embodiment, wherein forming the nonwoven web by foam forming includes depositing a first foam and a second foam onto a forming surface, the first foam including water and a plurality of first binder fibers, and the second foam including water and a plurality of second binder fibers.

[0149] Twenty-fifth exemplary embodiment: The method of the twenty-third exemplary embodiment or the twenty-fourth exemplary embodiment, wherein the first layer comprises a plurality of first binder fibers, and the second layer comprises a plurality of second binder fibers and a plurality of superabsorbent particles.

[0150] Twenty-sixth exemplary embodiment: The method as described in any one of the twenty-third exemplary embodiment to the twenty-fifth exemplary embodiment, wherein the first layer includes a plurality of first binder fibers, the second layer includes a plurality of second binder fibers, and the second binder fibers are different from the first binder fibers.

[0151] Twenty-seventh exemplary embodiment: The method according to the twenty-sixth exemplary embodiment, wherein the second binder fiber comprises PET fiber.

[0152] Twenty-eighth example embodiment: The method as described in any one of the twenty-third to twenty-seventh example embodiments, wherein the protrusions include a plurality of circular corrugations.

[0153] Twenty-ninth exemplary embodiment: The method of any one of the twenty-third to twenty-eighth exemplary embodiments, wherein the void volume of the first layer increases as the nonwoven web relaxes.

[0154] Thirtieth exemplary embodiment: The method as described in any one of the twenty-third exemplary embodiment to the twenty-ninth exemplary embodiment, wherein the thickness of the second layer is greater than the thickness of the first layer.

[0155] Thirty-first exemplary embodiment: The method of any one of the twenty-third to thirtieth exemplary embodiments, wherein the nonwoven web is a double-layer nonwoven web, and the plurality of layers includes only the first layer and the second layer.

[0156] Thirty-second exemplary embodiment: A nonwoven article comprising a nonwoven material manufactured according to the method of any one of the twenty-third to thirty-first exemplary embodiments.

Claims

1. A method for forming a nonwoven material, comprising: forming a nonwoven web having a plurality of layers by foam forming; at least partially solidifying a first layer of the plurality of layers while the nonwoven web is under tension; After at least partially curing the first layer, curing a second layer of the plurality of layers while the nonwoven web is under tension; as well as The nonwoven web is relaxed such that the second layer contracts and the first layer is deformed to produce a plurality of projections at an outer surface of the first layer facing away from the second layer.

2. The method of claim 1, wherein forming the nonwoven web by foam forming comprises depositing a first foam and a second foam onto a forming surface, the first foam comprising water and a plurality of first binder fibers, the second foam comprising water and a plurality of second binder fibers.

3. The method of claim 1, wherein the first layer comprises a plurality of first binder fibers and the second layer comprises a plurality of second binder fibers and a plurality of superabsorbent particles.

4. The method of claim 1, wherein after said curing of said first layer, the water content in said second layer is greater than the water content in said first layer.

5. The method of claim 1, wherein the first layer comprises a plurality of first binder fibers, the second layer comprises a plurality of second binder fibers, and the second binder fibers are different from the first binder fibers.

6. The method of claim 5, wherein the second binder fibers comprise PET fibers. The method of claim 1 , wherein the protrusions comprise a plurality of circular corrugations.

8. The method of claim 1, wherein the void volume of the first layer increases as the nonwoven web relaxes.

9. The method of claim 1, wherein during said curing of said first layer, said first layer at least partially adheres to said second layer.

10. The method of claim 1, wherein a thickness of the second layer is greater than a thickness of the first layer.

11. The method of claim 1, wherein: At least partially curing the first layer comprises heating the first layer, a water content in the first layer decreasing during the heating of the first layer; and Curing the second layer includes heating the second layer, the water content in the second layer decreasing during the heating of the second layer.

12. The method of claim 1, wherein at least partially curing the first layer comprises curing a first portion of the first layer at a different rate than a second portion of the first layer.

13. The method of claim 1, wherein the nonwoven web is a double-layer nonwoven web and the plurality of layers includes only the first layer and the second layer.

14. A nonwoven article comprising a nonwoven material produced according to the method of claim 1.

15. A nonwoven material comprising: A foam-formed nonwoven web having a first layer and a second layer, The first layer is contracted relative to the second layer so that the first layer forms a plurality of protrusions on an outer surface of the first layer facing away from the second layer.

16. The nonwoven material of claim 15, wherein the first layer comprises a plurality of first binder fibers and the second layer comprises a plurality of second binder fibers and a plurality of superabsorbent particles.

17. The nonwoven material of claim 15, wherein the first layer comprises a plurality of first binder fibers, the second layer comprises a plurality of second binder fibers, and the second binder fibers are different from the first binder fibers.

18. The nonwoven material of claim 17, wherein the second binder fibers comprise PET fibers.

19. The nonwoven material of claim 15, wherein the projections comprise a plurality of circular corrugations.

20. The nonwoven material of claim 15, wherein the second layer has a thickness greater than a thickness of the first layer.

21. An absorbent article comprising the nonwoven material of claim 15, wherein when the absorbent article is worn by a wearer of the absorbent article, the outer surface of the first layer faces the wearer.

22. A method for forming a nonwoven material, comprising: forming a nonwoven web having a plurality of layers by foam forming; heating a first layer of the plurality of layers in the nonwoven web while the nonwoven web is under tension, the water content of the first layer decreasing during the heating of the first layer; heating a second layer of the plurality of layers in the nonwoven web after heating the first layer and while the nonwoven web is under tension, the water content of the second layer decreasing during the heating of the second layer; as well as While heating the second layer, the nonwoven web is relaxed such that the first layer is deformed to have a plurality of projections at an outer surface of the first layer facing away from the second layer.

23. A method for forming a nonwoven material, comprising: forming a nonwoven web having a plurality of layers by foam forming, a first layer and a second layer of the plurality of layers being at least partially interconnected; as well as The nonwoven web is heated so that the second layer shrinks less than the first layer, and the first layer is deformed to produce a plurality of projections at an outer surface of the first layer facing away from the second layer.

24. The method of claim 23, wherein forming the nonwoven web by foam forming comprises depositing a first foam and a second foam onto a forming surface, the first foam comprising water and a plurality of first binder fibers and the second foam comprising water and a plurality of second binder fibers.

25. The method of claim 23, wherein the first layer comprises a first plurality of binder fibers and the second layer comprises a second plurality of binder fibers and a plurality of superabsorbent particles.

26. The method of claim 23, wherein the first layer comprises a plurality of first binder fibers, the second layer comprises a plurality of second binder fibers, and the second binder fibers are different from the first binder fibers.

27. The method of claim 26, wherein the second binder fibers comprise PET fibers.

28. The method of claim 23, wherein the protrusions comprise a plurality of circular corrugations.

29. The method of claim 23, wherein the void volume of the first layer increases as the nonwoven web relaxes.

30. The method of claim 23, wherein the second layer has a thickness greater than a thickness of the first layer.

31. The method of claim 23, wherein the nonwoven web is a double-layer nonwoven web and the plurality of layers includes only the first layer and the second layer.

32. A nonwoven article comprising a nonwoven material made according to the method of claim 23.

33. The method of claim 23, wherein the second layer comprises fibers capable of hydrogen bonding, and the shrinkage of the second layer is due at least in part to capillary condensation and hydrogen bonding during drying.

34. The method of claim 33, wherein the fibers capable of forming hydrogen bonds comprise wood pulp.

35. The method of claim 23, wherein the second layer comprises a superabsorbent material that partially swells after forming the nonwoven web by foam forming, and the shrinkage of the second layer is at least partially due to shrinkage of the superabsorbent material during the heating of the nonwoven web.

36. The method of claim 23, wherein the second layer comprises a heat shrink material, and the shrinkage of the second layer is due at least in part to shrinkage of the heat shrink material during the heating of the nonwoven web.

37. The method of claim 36, wherein the heat shrinkable material comprises PLA staple fibers.

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