Headbox for manufacturing substrate

Abstract

Apparatus and methods for producing a substrate are described. A headbox is also provided. The headbox can include at least one flow section. The at least one flow section can include a constriction zone; a slicing area; an expansion zone; and a formation region. A method for producing a web is also provided. The method can include depositing a fiber slurry into the shrink zone. The fiber slurry can then be passed from the contraction zone through a slicing zone and into an expansion zone. The fiber slurry can then be flowed from the expansion zone into a formation zone. The slurry is transportable over a moving forming surface. Fluid can be discharged from the fibrous slurry through the forming surface within the forming region to form an initial web. The initial web can be dried.

Description

Technical Field

[0001] The present disclosure generally relates to apparatus and methods for forming substrates. More specifically, the present disclosure relates to foam forming methods and apparatus for forming substrates. Background Art

[0002] 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.Some substrates in the substrates in these products can include natural fibers and / or synthetic fibers.In some products, some substrates can also include different types of components, to provide additional functions to substrates and / or the final product itself.

[0003] For example, it may be desirable to add such a component on the substrate to include superabsorbent material (SAM). SAM can be constructed in the form of particles or fibers, and is generally used in substrates to increase absorption capacity. The absorption system of personal care absorbent products (such as diapers) generally includes SAM. There is a process for forming substrates with SAM, including utilizing a forming chamber to mix SAM particles or fibers with cellulose fibers to form an absorbent core. These processes are usually completed in a dry environment because SAM is difficult to handle due to the volume increase and other potential shortcomings caused by absorbing fluids and gelling when wet. However, alternative substrate formation processes can adopt fluids (such as liquids) to form substrates that provide various other characteristics and efficiency in terms of the manufacture and performance of this type of substrate.

[0004] In order to improve various properties of tissue paper webs, webs have been formed according to a foam forming process. During the foam forming process, a slurry of fibers is formed and spread onto a moving porous conveyor belt for producing an embryonic web. The foam formed web may exhibit improvements in bulk, stretch, thickness, and / or absorbency.

[0005] In addition to tissue webs, foam forming can be used to make all different types of webs and products. For example, relatively long fibers and synthetic fibers can be incorporated into webs using the foam forming process. Therefore, the foam forming process can be more versatile than many wet-laid processes.

[0006] However, when webs are formed according to foam forming processes, problems have been encountered in controlling the orientation of fibers in the resulting webs. For example, during production of the web, the foam suspends the fibers and transports the fibers downstream at flow rates that exhibit plug flow characteristics and / or low yield stress. As a result, many foam forming processes produce webs in which the fibers are primarily oriented in the longitudinal direction of the web manufacturing process, particularly when the foam-formed web is formed on an inclined surface.

[0007] Therefore, there is a need for a system and method for producing a foam-forming web in which fiber orientation is controlled. Specifically, there is a need for a method and system that can produce a foam-forming web in which the fiber orientation is more random and such that the fibers are oriented in both the machine direction and the cross-machine direction. Producing a web with a more uniform distribution of fiber orientation can provide various benefits and advantages. For example, the web can exhibit greater uniformity of physical properties between the machine direction of the web and the cross-machine direction of the web. There is also a need to develop an improved headbox for forming a substrate. Summary of the invention

[0008] In one embodiment, a headbox is provided. The headbox may include a longitudinal direction, a transverse direction, and a height direction. The headbox may also include at least one flow section. The at least one flow section may include a bottom surface and a top surface. The top surface may be opposite to the bottom surface in the height direction. The at least one flow section may include a contraction zone; a slicing zone; an expansion zone; and a forming zone. The contraction zone may have an initial height (t i ), and this height can be shrunk to the slice height (t s The slicing zone may be in fluid communication with the downstream end of the contraction zone and may have a slicing length (l s ) and in the slice length (l s ) is equal to the slice height (t s The expansion zone may be in fluid communication with the downstream end of the slicing zone and may have a height equal to the slicing height (t s ) and the height can expand to the expanded height (t1) in the longitudinal direction. The formation zone can be in fluid communication with the downstream end of the expansion zone and can have a starting height equal to the expanded height (t1), and the height can shrink to the formation height (t2) in the longitudinal direction.

[0009] In another embodiment, a method for producing a web is provided. The method may include depositing a slurry of fibers and optionally at least one other solid component (e.g., superabsorbent particles) into a contraction zone. The fiber slurry can then flow from the contraction zone through a slicing zone and into an expansion zone. The slurry may have a fluid flow rate, and the slicing zone may have a height (t s ) and length (l s ), so that the fiber slurry can experience turbulence in the expansion zone. The fiber slurry can then be caused to flow from the expansion zone into the forming zone. The slurry can be transported on the moving forming surface. The fluid can be discharged from the fiber slurry through the forming surface in the forming zone to form an embryonic web. The embryonic web can be dried.

[0010] Other features and aspects of the disclosure are discussed in greater detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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:

[0012] Figure 1 is a process diagram of an exemplary method for introducing a component into a fluid supply and forming a substrate including the component according to one embodiment of the present disclosure;

[0013] Figure 2 Is it like Figure 1 Detailed schematic diagram of the component feed system, two mixing joints and two fluid supplies upstream of the headbox as depicted in the process schematic diagram in;

[0014] Figure 3 yes Figure 2 A cross-sectional view of a first mixing joint and an outlet conduit of a component feed system;

[0015] Figure 4A is a process diagram of an alternative exemplary method for introducing a component into a fluid supply and forming a substrate including the component according to another embodiment of the present disclosure;

[0016] Figure 4B is a process diagram of another alternative exemplary method for introducing a component into a fluid supply and forming a substrate including the component according to another embodiment of the present disclosure;

[0017] Figure 4C is a process diagram of another alternative exemplary method for introducing a component into a fluid supply and forming a substrate including the component according to another embodiment of the present disclosure;

[0018] Figure 5 is a side cross-sectional view of an exemplary headbox;

[0019] Figure 6 is a side cross-sectional view of an exemplary headbox having a top layer of flow channels.

[0020] 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

[0021] 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.

[0022] The present disclosure relates to methods and apparatus capable of producing substrates comprising components.While the present disclosure provides examples of substrates made by foam forming, it is contemplated that the methods and apparatus described herein can be used to benefit wet-laid and / or air-laid manufacturing processes.

[0023] 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.

[0024] 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.

[0025] definition

[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 providing a substrate region in the height direction of the 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] The term "ply" refers to discrete layers within a multi-layer product, wherein individual plies may be arranged juxtaposed to one another.

[0035] The term "twisted" or "bonded" or "coupled" herein refers to the joining, adhering, connecting, attaching, etc. of two elements. Two elements will be considered twisted, bonded or coupled together when they are joined, adhered, connected, attached, etc. directly to each other or indirectly to each other, such as when each is directly bonded to an intermediate element. The twisting, bonding or coupling of one element to another element can be performed by continuous or intermittent bonding.

[0036] 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.

[0037] As used herein, the term "machine direction" refers to the direction of travel of the forming surface upon which the fibers are deposited during the formation of the nonwoven web.

[0038] As used herein, the term "height direction" refers to a direction from a top surface to a bottom surface of a flow segment and perpendicular to the longitudinal direction defined above.

[0039] As used herein, the term "lateral" refers to a direction perpendicular to both the longitudinal direction and the height direction defined above.

[0040] As used herein, the term "initial height" or "t i ” refers to the distance between the top surface and the bottom surface at the most upstream portion of the contraction zone.

[0041] As used herein, the term "slice height" or "t s " refers to the distance between the top surface and the bottom surface over the length of the slice zone. The slice height is also the distance between the top surface and the bottom surface at the most downstream portion of the contraction zone. The slice height is also the distance between the top surface and the bottom surface at the most upstream portion of the expansion zone.

[0042] As used herein, the term "slice length" or " s ” refers to the distance along the longitudinal direction over which the slice height is maintained.

[0043] As used herein, the term "expansion height" or "t1" refers to the distance between the top surface and the bottom surface at the most downstream portion of the expansion zone.

[0044] As used herein, the term "formation height" or "t2" refers to the distance between the top surface and the bottom surface at the most downstream portion of the formation zone.

[0045] 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.

[0046] 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:

[0047]

[0048] in

[0049] k = maximum fiber length

[0050] x i =Fiber length

[0051] n i = Number of fibers of length xi

[0052] n = total number of fibers measured.

[0053] 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.

[0054] As used herein, the term "staple fibers" refers to discontinuous fibers made from synthetic polymers such as polypropylene, polyester, post-consumer recycled (PCR) fibers, polyester, nylon, 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.

[0055] Generally speaking, the present disclosure relates to a method and system for forming a nonwoven web from a liquid or foam suspension of fibers and optionally at least one other solid component. The system and method of the present disclosure uses a unique and specially designed headbox that not only produces a web having a uniform but random fiber orientation, but also produces in a manner that promotes a uniform distribution of another solid component (such as superabsorbent particles) that may be included in the fiber slurry. The headbox design of the present disclosure is particularly suitable for use in tandem with other similar headboxes to produce a uniform nonwoven web having uniform properties.

[0056] In one embodiment, the disclosed headbox design includes an initial contraction zone that may be arcuate in height or in the Z direction. The contraction zone terminates at a slicing zone that forms a slot through which the slurry is fed. After the slicing zone, the slurry enters an expansion zone that may gradually increase in height. The headbox is designed so that the velocity of the slurry increases through the slicing zone and then flows into the expansion zone where turbulent mixing of the slurry occurs. In one aspect, the slicing zone followed by the expansion zone may cause a hydraulic jump that randomly redirects the fibers in the slurry while also uniformly combining the fibers with other solid components.

[0057] The width of the headbox may also expand in the transverse direction as the slurry travels from the contraction zone to the expansion zone. For example, in one embodiment, the headbox may taper and increase in width over the entire length of the headbox, or at least over the length of the expansion zone. Thus, not only does mixing of the fibers and solid components occur as the slurry flows through the headbox, but the flow of the slurry also spreads and increases in width. As described above, multiple headboxes may be placed in series for forming a web over the entire width of the forming surface. This headbox design is particularly suitable for producing a web from a series of laterally spaced headboxes without any significant fiber non-uniformity occurring where the slurry flows exiting the different headboxes converge.

[0058] In one embodiment, the size of the headbox can be adjustable. For example, the top of the headbox can be movable toward and away from the bottom of the headbox. Thus, the different sizes of the headbox can be varied and controlled according to the specific application and based on the characteristics of the slurry. The headbox design of the present disclosure maintains a high flow rate of the slurry relative to any stationary surface, thereby preventing agglomeration of fibers contained in the slurry or agglomeration of solid components (such as superabsorbent particles). Overall, the flow disturbance created by the headbox design provides web fiber randomization while diffusing the flow of the slurry without creating a coaxial flow, which has been problematic in prior art systems.

[0059] Referring to the figures, in one embodiment, the present disclosure is directed to a method and apparatus 10 that can form a substrate 12 . Figure 1 A schematic diagram of an exemplary apparatus 10 that can be used as part of a foam forming process to manufacture a substrate 12 as a foam forming product is provided. The apparatus 10 may include a first tank 14 configured to hold a first fluid supply 16. In some embodiments, the first fluid supply 16 may be a foam. The first fluid supply 16 may include a fluid provided by a fluid supply 18. In some embodiments, the first fluid supply 16 may include a plurality of fibers provided by a supply of fibers 20, however, in other embodiments, the first fluid supply 16 may not have a plurality of fibers. The first fluid supply 16 may also include a surfactant provided by a surfactant supply 22. In some embodiments, the first tank 14 may include a mixer 24, which will be discussed in more detail below. The mixer 24 may mix (e.g., agitate) the first fluid supply 16 to mix the fluid, the fibers (if present), and the surfactant with air or some other gas to produce a foam. The mixer 24 may also mix the foam with the fibers (if present) to produce a foam suspension of the fibers, wherein the foam holds and separates the fibers to facilitate the 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 qualities of substrate 12, including, for example, strength and quality visual appearance.

[0060] The apparatus 10 may also include a second tank 26 configured to hold a second fluid supply 28. In some embodiments, the second fluid supply 28 may be a foam. The second fluid supply 28 may include a fluid provided by a supply of fluid 30 and a surfactant provided by a supply of surfactant 32. In some embodiments, the second fluid supply 28 may include a plurality of fibers in addition to or in lieu of the fibers present in the first fluid supply 16. In some embodiments, the second tank 26 may include a mixer 34. The mixer 34 may mix the second fluid supply 28 to mix the fluid and the surfactant with air or some other gas to produce a foam.

[0061] 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 activated to form a foam. In some embodiments, the foaming fluid and other components are activated to form a porous foam having an air content greater than about 50% by volume and ideally an air content greater than about 60% by volume. In some aspects, the highly expanded foam is formed to have an air content between about 60% and about 95%, and in other aspects, between about 65% and about 85%. In some embodiments, the foam can be activated to introduce a 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 some embodiments, the ratio of air: 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.

[0062] Foam can be produced by one or more means 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 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 the components and air. In a particular 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 rotors or impellers rotate 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 necessary to achieve the desired mixing and shearing, in certain embodiments, suitable rotor speeds may be greater than about 500 rpm, and, for example, between about 1000 rpm and about 6000 rpm or between about 2000 rpm and about 4000 rpm. In certain 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.

[0063] 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 one 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., 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 be mixed and acted to form the initial foam before any solids are added. If desired, the fiber can then be added to the water / surfactant foam, which then further acts to form the final foam. Alternatively, the fluid 18 and fibers 20 (such as high density cellulose pulp) can 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.

[0064] 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 may vary depending on the specific application and various factors (such as the fiber raw material used). In some embodiments, for example, the foam density of the foam may be greater than about 100 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. The foam density is generally less than about 800 g / L, such as less than about 500 g / L, such as less than about 400 g / L, such as less than about 350 g / L. In some embodiments, for example, a lower density foam is used with a foam density generally less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L.

[0065] In some 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 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. In addition, as discussed further below, in some embodiments, the apparatus may be provided with a single pump that can pump a single fluid supply into the first fluid supply 16 and the second fluid supply 28.

[0066] like Figure 1 and Figure 2 As shown, the apparatus 10 may also include a component feed system 40. 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 area 42 and may be used to refill the supply of the component 44 to the component supply area 42.

[0067] In some embodiments, the component feed system 40 may include a solid volumetric pump. Some examples of solid volumetric pumps that can be used herein may 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 can be used for the component feed system 40, such as batching feeders, such as those manufactured by Christy Machine & Conveyor, Fremont, Ohio. In some embodiments, the component feed system 40 may also be configured as a conveyor system.

[0068] 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 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 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 embodiments, the fluid control system 50 may further include a bleed hole 54 .

[0069] The supply of component 44 can be in the form of particles and / or fibers. In one embodiment described herein, the supply of component 44 can be a superabsorbent material (SAM) in the form of particles. In some embodiments, SAM can be in the form of fibers. Of course, as further described below, other types of components can 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 components 44 that are most suitable for being maintained in a dry environment, wherein minimal exposure to the fluid or foam used in the apparatus 10 and method described herein.

[0070] refer to Figures 1 to 3 In some embodiments, the apparatus 10 and methods described herein may include a first mixing joint 56 and a second mixing joint 58. In a preferred 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. Figure 3 As shown, the first mixing joint 56 may include a first inlet 60 and a second inlet 62. The first inlet 60 may be in fluid communication with the supply of component 44 via the outlet conduit 46. The second inlet 62 may be in fluid communication with the second fluid supply 28. The first mixing joint 56 may also include a discharge port 64.

[0071] In a preferred embodiment, the first mixing joint 56 can be configured as a coaxial injector. For example, in a preferred embodiment, the first mixing joint 56 can be configured such that the first inlet axis 66 of the first inlet 60 of the first mixing joint 56 is coaxial with the outlet axis 68 of the outlet conduit 46 that provides the supply of the component 44. The first mixing joint 56 can also be configured such that the discharge axis 70 of the discharge port 64 is coaxial with the outlet axis 68 of the outlet conduit 46. Therefore, the first mixing joint 56 can be configured such that the first inlet axis 66 of the first inlet 60 can be coaxial with the discharge axis 70 of the discharge port 64 of the first mixing joint 56. The second inlet 62 that provides the second fluid supply 28 to the first mixing joint 56 can be disposed to enter the first mixing joint 56 on one side of the first mixing joint 56. This configuration of having the supply of component 44 delivered in the first inlet 60 in a manner coaxial with the discharge axis 70, rather than having the second fluid supply 28 enter at the first inlet 60, is contrary to most injector configurations that use the motive force of the fluid supply to mix the fluid supply and components, but provides the advantages of the first mixing joint 56 as described herein.

[0072] When configured as an ejector, the first mixing junction 56 can mix a supply of component 44 from the component feed system 40 with the second fluid supply 28. The second fluid supply 28 provides motive pressure to the supply of component 44 by transferring the second fluid supply 28 into the first mixing junction 56 at the second inlet 62 and passing through the first mixing junction 56. The motive pressure can create a vacuum on the supply of component 44 and the component feed system 40 to help draw the supply of component 44 to mix and become entrained in the second fluid supply 28. In some embodiments, the motive pressure can create a vacuum of less than 1.5 in Hg on the supply of component 44, however, in other embodiments, the motive pressure can create a vacuum of 5 in Hg or more, or 10 in Hg or more, on the supply of component 44.

[0073] The fluid control system 50 may help manage the proper distribution and entrainment of the supply of component 44 into the second fluid supply 28, and may help control fluid entrainment within the second fluid supply 28 downstream of the component feed system 40. For example, if there is no housing 52 surrounding the component feed system 40, additional fluid (e.g., ambient gas, such as air) may be entrained into the second fluid supply 28 as the supply of component 44 is metered into the second fluid supply 28. It may also be the case that when the second fluid supply 28 generates dynamic pressure on the component feed system 40, the vacuum pull on the supply of component 44 may cause additional air to be entrained in the second fluid supply 28. In some cases, it may be desirable to entrain additional air in the second fluid supply 28, however, in other cases, it may be desirable to control the amount of gas in the second fluid supply 28 while inputting the supply of component 44 into the second fluid supply 28 at the first mixing joint 56. For example, in some cases where the second fluid supply 28 is a foam, it may be desirable to keep the gas content in the foam relatively fixed as the foam passes through the first mixing joint 56. Thus, the fluid control system 50 can help control the pressure on the component feed system 40 and the gas flow through the component feed system to help prevent or at least control the amount of gas entrained in the second fluid supply 28 when the supply of component 44 is mixed with the second fluid supply 28, and can help offset the dynamic pressure on the supply of component 44 and the component feed system 40 generated by the second fluid supply 28.

[0074] In some embodiments, the fluid control system 50 can include a sealed component feed system 40. For example, as discussed above, the fluid control system 50 can include a housing 52 to provide a seal on the component feed system 40. Sealing the component feed system 40 can help prevent additional air from being entrained in the second fluid supply 28 when the supply of component 44 is introduced into the second fluid supply 28 in the first mixing joint 56.

[0075] However, in some embodiments, it may be beneficial for the fluid control system 50 to also include additional capabilities. For example, in some embodiments, the fluid control system 50 may include a bleed hole 54. The bleed hole 54 may be configured to bleed a fluid flow (such as an atmospheric airflow) to provide additional fluid flow control to the component feed system 40. The bleed hole 54 can bleed an airflow (e.g., an airflow) within the housing 52 to help control the air flow and pressure around the component feed system 40 within the housing 52. It has been found that by providing a bleed hole 54 to provide the introduction of some atmospheric airflow to the component feed system 40, the splashback of the second fluid supply 28 in the first mixing joint 56 can be reduced or eliminated. Reducing the splashback of the second fluid supply 28 in the first mixing joint 56 can help prevent the component feed system 40 from becoming blocked or requiring cleaning, especially in the case where the component feed system 40 may be delivering dry particles such as SAM. Under other process conditions, for similar reasons, it may be desirable to completely seal the component feed system 40.

[0076] Additionally or alternatively, the fluid control system 50 may be configured to provide additional gas flow (e.g., air flow) and / or positive pressure to prevent backfilling of the component feed system 40 in certain circumstances (such as if a downstream obstruction occurs in the apparatus 10 beyond the first mixing joint 56). In the event that such an obstruction creates increased pressure, the second fluid supply 28 may be expected to backfill the component feed system 40. Backfilling fluid into the component feed system 40 may be detrimental to processing, especially in the event that the supply of component 44 is a dry component (e.g., SAM). A fluid control system 50 configured to provide positive pressure to the component feed system 40 may help prevent such backfilling of the component feed system 40.

[0077] It is also contemplated that other additional aspects of the fluid control system 50 may be used to maintain gas flow and pressure at appropriate levels for the component feed system 40, including, but not limited to, supplying a vacuum to the component feed system 40 in addition to or in lieu of venting air at the vent 54 and / or the positive pressure described above.

[0078] like Figure 3As shown, in some embodiments, the first mixing joint 56 can also include a venturi section 72. The venturi section 72 can be a necked region of the first mixing joint 56 that can increase the velocity of the second fluid supply 28 through the venturi section 72, and thus can increase the vacuum pressure created by the second fluid supply 28 on the supply of component 44 in the component feed system 40, and can help entrain the supply of component 44 within the second fluid supply 28. In some embodiments, a distal end 74 of an outlet conduit 46 that provides the supply of component 44 to the first mixing joint 56 can be disposed in the venturi section 72. The position of the distal end 74 of the outlet conduit 46 can be adjusted within the venturi section 72 as a way to control the pressure of the second fluid supply 28 as it exits the first mixing joint 56 and the component feed system 40.

[0079] The first mixing joint 56 may also provide pressure control over the transfer of the second fluid supply 28 including the component 44 as it exits the discharge port 64 of the first mixing joint 56, compared to when the second fluid supply 28 enters the first mixing joint 56. The second fluid supply 28 may be transferred at the second fluid pressure before the first mixing joint 56. The second fluid supply 28 including the component from the supply of the component 44 may exit the discharge port 64 of the first mixing joint 56 at the discharge pressure. The pressure difference between the second fluid pressure before the first mixing joint 56 and the discharge pressure may be controlled. In some embodiments, the pressure difference may be controlled by changing the flow rate of the second fluid supply 28. In some embodiments, the pressure difference may be controlled by the position of the distal end 74 of the outlet conduit 46 in the venturi section 72 of the first mixing joint 56. For example, if the distal end 74 of the outlet conduit 46 is moved further into the venturi section 72, the area of ​​the second fluid supply 28 flowing through the venturi section 72 is reduced, and thus the supply pressure of the second fluid supply 28 is increased. If the distal end 74 of the outlet conduit 46 is moved further out of the venturi section 72 (i.e., back toward the component feed system 40), the area through which the second fluid supply 28 flows through the venturi section 72 increases, and thus the supply pressure of the second fluid supply 28 entering the first mixing junction 56 decreases, and the vacuum on the component feed system 40 also decreases. In some embodiments, the pressure difference between the second fluid pressure before the first mixing junction 56 and the discharge pressure is preferably controlled to be less than or equal to 25 pounds per square inch (psi), or more preferably less than 20 psi, or less than 15 psi, or less than 10 psi, or less than 5 psi.

[0080] Another feature of the first mixing joint 56 that can produce enhanced mixing and transfer of the supply of component 44 into the second fluid supply 28 in the first mixing joint 56 can be that the second inlet 62 providing the second fluid supply 28 is located upstream of the distal end 74 of the outlet conduit 46 that provides the supply of component 44 from the component feed system 40 to the first mixing joint 56. With this configuration, the second fluid supply 28 can enter the first mixing joint 56 upstream of the supply of component 44 to prevent any supply of component 44 from bonding or adhering to the inner surface of the first mixing joint 56. Figure 3 In the illustrated embodiment, the coaxial nature of the outlet axis 68 of the outlet conduit 46 and the discharge axis 70 of the first mixing joint 56 and the upstream inlet of the second fluid supply 28 into the first mixing joint 56 can create an annular fluid protection around the inlet of the supply of component 44 as it is entrained in the second fluid supply 28 in the first mixing joint 56.

[0081] It should be noted that although Figures 1 to 3 4 and 56, but it is contemplated that the outlet conduit 46 may be split into two or more conduits to feed two or more first mixing joints 56 for mixing the supply of component 44 with the second fluid supply 28. In such a configuration, the second fluid supply 28 may include as many conduits as first mixing joints 56. By having more than one outlet conduit 46 and more than one first mixing joint 56 to mix the supply of component 44 with the second fluid supply 28, a greater flow rate of the second fluid supply 28 including components from the supply of component 44 may be achieved.

[0082] In some embodiments, it is also contemplated that the first mixing joint 56 may be an ejector of a different configuration rather than a coaxial ejector as described above. For example, it is contemplated that the first mixing joint 56 may be an ejector in the shape of a slot ejector.

[0083] Reference again Figure 1, in some embodiments, the apparatus 10 may include a second mixing joint 58. The second mixing joint 58 may provide functionality 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, it 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 thereof (e.g., fluid 18, fibers 20, surfactant 22) with the second fluid supply 28 and any components thereof (e.g., fluid 30, surfactant 32), as well as 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 through the discharge port 78 of the second mixing joint 58 to a headbox 80. In some embodiments, as Figure 3 As shown, there may be a space between the discharge port 78 of the second mixing joint 58 and the headbox 80. However, in other embodiments, the discharge port 78 of the second mixing joint 58 may be integral with the headbox 80.

[0084] In one aspect, discharge port 78 comprises a plurality of tubes that inject slurry into headbox 80. Using a plurality of tubes can promote preservation of foam. For example, a plurality of inlet tubes can help maintain the inlet fluid velocity into headbox 80. For example, the system can include at least 2 tubes, at least 3 tubes, at least 4 tubes, at least 5 tubes, and less than about 30 inlet tubes, such as less than about 20 inlet tubes, such as less than about 15 inlet tubes.

[0085] An alternative embodiment of an apparatus 110 and method for forming a substrate 12 is depicted in Figure 4A Unless otherwise specified in this document, Figure 4A With Figures 1 to 3 The apparatus 10 and method described above have the same components. Figure 4A The device 110 comprises only a first tank 14 for holding a first fluid supply 16 . Figure 4A The apparatus 110 and method does not include the second tank 26 containing the second fluid supply 28. The first fluid supply 16 may include a supply of fluid 18, a supply of fiber 20, and a supply of surfactant 22. The apparatus 110 may also include the above reference Figures 1 to 3 The component feed system 40, fluid control system 50 and mixing joint 56 are described. Based on this configuration, the first pump 36 can transfer the first fluid supply 16 to the first mixing joint 56. As previously described, the component feed system 40 can transfer the supply of the component 44 to the first mixing joint 56. In a preferred embodiment, the first mixing joint 56 can be an ejector, and more preferably, as described in reference Figure 3The coaxial ejector shown. The first mixing joint 56 can mix the first fluid supply 16 with the components from the supply of component 44 and provide a resulting slurry 76 that is discharged from the discharge port 64 of the first mixing joint 56 and transferred to the slurry box 80. In some embodiments, the discharge port 64 of the first mixing joint 56 can be separate from the slurry box 80, however, in some embodiments, the discharge port 64 of the first mixing joint 56 can be integral with the slurry box 80. In some embodiments, the first fluid supply 16 can include a fluid 18 and a surfactant 22 to mix with the supply of component 44 to provide the resulting slurry 76, but without any fibers. In other embodiments, the first fluid supply 16 can include a fluid 18, fibers 20, and a surfactant 22 to mix with the supply of component 44 to provide the resulting slurry 76.

[0086] Figure 4B 210 and method for forming substrate 12. Apparatus 10 may include a first pump 36 that may be in fluid communication with first fluid supply 16. First fluid supply 16 may include a supply of fluid 18 and surfactant 22. First fluid supply 16 may be split at joint 17. First fluid supply 16 may continue through two control valves 23. First fluid supply 16 may continue through one of control valves 23 in conduit 19 and toward headbox 80. A supply of fibers 20 may be added to first fluid supply 16 through control valve 23. Preferably, the supply of fibers 20 may be provided to first fluid supply 16 in a supply of fluid, such as foam.

[0087] When the first fluid supply is split at the junction 17, the first fluid supply 16 can be pumped through the second control valve 23 in the conduit 21 toward the first mixing junction 56. The fluid supply in the conduit can be referred to as the second fluid supply 28. The second fluid supply 28 can include a supply of fluid 18 and surfactant 22 (i.e., from the first fluid supply 16). In some embodiments, as Figure 4B As shown, the supply of fibers 20' is preferably added to the second fluid supply 28. Preferably, the supply of fibers 20' may be provided to the first fluid supply 16 in a supply of fluid, such as a foam.

[0088] exist Figure 4BIn the illustrated embodiment, the supply of component 44 may be added to the second fluid supply 28 at the first mixing joint 56 as described above. The apparatus 210 may include an output 65 of the first mixing joint 56, which includes the component 44 downstream of the discharge 64 of the first mixing joint 64. The fluid in the output 65 of the first mixing joint 56 and the supply of component 44 may provide a first input 67 into the headbox 80. The first fluid supply 16 may provide a second input 69 into the headbox 80. The first input 67 may be separated from the second input 69 into the headbox 80. For example, in some embodiments, the first input 67 including the component 44 may be separated from the second input 69 by a height-directed separator 71 (also referred to as a sheet), and thus when the fluid supplies 16, 28 are transferred through the headbox 80 to provide the resulting slurry 76, the fluid supplies 16, 28 may be separated from each other for at least a portion of the headbox 80. In doing so, the resulting slurry 76 may provide two distinct layers to provide a two-layer substrate 12.

[0089] Figure 4C Another alternative embodiment is shown. Figure 4C Similar to Figure 2 The configuration described, however, Figure 4C In the configuration of FIG. 4 , a bleed hole 154 is provided that can provide a controlled fluid flow to the supply of component 44 after the component 44 enters the outlet conduit 46 of the component feed system 40, but upstream of the first mixing joint 56. This configuration can provide a fluid (e.g., a liquid, a gas, or a foam) to the supply of component 44 to help control fluid entrainment within the second fluid supply 28 as the supply of component 44 mixes with the second fluid supply 28 in the first mixing joint 56. For example, in one embodiment, the addition of a foam flow in the bleed hole 154 can help prevent additional gas (e.g., air) from being entrained in the supply of component 44 as it mixes with the second fluid supply 28.

[0090] Regardless of whether the apparatus 10, 110, 210 and method for transferring the resulting slurry 76 is as described herein, or another apparatus and / or method, a headbox 80 may be provided to further transfer the resulting slurry 76 to form the substrate 12. Figures 5 and 6 As shown, the headbox 80 may have a longitudinal direction 81 and a transverse direction 83. The longitudinal direction 81 is the direction in which the resulting slurry 76 is transferred through the headbox 80. For clarity, the longitudinal direction 81 is the direction in which the resulting slurry 76 is transferred through the headbox 80. Figures 5 and 6 The resulting slurry 76 is not shown.

[0091] The headbox 80 may include at least one flow section 82. Figures 5 and 6 In the embodiment of the headbox 80 shown, the headbox 80 includes a flow section 82. Figures 5 and 6 As illustrated, the flow segment 82 may include four zones in the longitudinal direction 81 .

[0092] The most upstream region (in the longitudinal direction 81) of the flow segment 82 may be a contraction region 130. The contraction region 130 may have an initial height (t i The height of the contraction zone 130 may contract to a slice height (t s ). The contraction zone may have an arc shape, for example, the top surface 120 may have a concave shape, and the bottom surface 100 may have a convex shape, which together may produce an arc shape of the side profile of the contraction zone 130. It is believed that the arc shape along the height direction 85 between the top surface 120 and the bottom surface 110 of the contraction zone 130 (together with the geometry of the contraction zone 130 in the plane defined by the longitudinal direction 81 and the transverse direction 83) may provide enhanced control of the flow of the resulting slurry 76, and may help reduce eddy or other turbulence of the flow of the resulting slurry 76 through the contraction zone, further increasing the above-mentioned advantages with respect to the components from the supply of the component 44. For example, it is believed that such an arc shape may provide a more consistent basis weight and fiber orientation across the transverse direction 83 in the formed substrate 12, particularly when used in a foam forming process.

[0093] The next downstream region (in the longitudinal direction 81) in the flow segment 82 may be a slicing region 140. The slicing region 140 may have a slicing length (l ) measured along the longitudinal direction 81. s The slicing region 140 may have a slicing height (t s ). Slice height (t s ) along the entire length of the slicing region 140 (ie, the slicing length (l s )) can be the same.

[0094] The next downstream region (in the longitudinal direction 81) in the flow segment 82 may be an expansion region 150. The expansion region may have a length equal to the slice height (t s The height of the expansion zone 150 may expand to an expansion height (t1) as the slurry 76 flows along the longitudinal direction 81.

[0095] The fiber slurry 76 is forced through the slicing zone 140. The slicing height (t s ) and slice length (l s) causes the speed and flow rate of the fiber slurry 76 to increase rapidly. The fiber slurry 76 then leaves the slicing zone 140 and is discharged into the expansion zone 150. The rapid increase in the speed of the fiber slurry 76 and the subsequent significant decrease causes significant turbulence to occur in the expansion zone 150, thereby causing the mixing of the fibers. Through this process, the orientation of the fibers becomes significantly more random, as opposed to being oriented only in the longitudinal direction 81. Therefore, the fiber orientation in the longitudinal direction 81 can be the same or similar to the fiber orientation in the transverse direction 83. After leaving the slicing zone 140, the fiber slurry 76 is then discharged in the forming zone 160 for holding and locking in the fiber orientation. In this way, a web having physical properties very similar to those in the transverse direction 83 in the longitudinal direction 81 can be produced.

[0096] As explained above, the fiber slurry 76 is accelerated in flow rate and velocity by the slicing zone 140 and then discharged into the expansion zone 150, which has an expansion volume, thereby allowing the velocity and flow rate of the foamed fiber suspension to be rapidly reduced, thereby inducing turbulence within the fluid and producing random fiber orientation. Turbulence refers to the flow of the foamed suspension, in which the fluid experiences irregular fluctuations or mixing compared to laminar flow in which the fluid moves in a smooth path or layer. For example, the foamed fiber suspension may experience turbulence within the expansion zone 150, causing the formation of fluid eddies and vortices, which significantly enhances the random distribution of the fibers within the foam.

[0097] The width of the headbox 80 over the flow section 82 can be uniform or can vary. In one aspect, for example, the width of the flow section 82 gradually increases from the contraction zone 130 to the expansion zone 150. In this way, the slurry of fibers and other solid components can be spread to form a nonwoven web. It has been found that the headbox 80 is particularly suitable for producing not only a uniform but random fiber distribution, but also a uniform distribution of other solid components (such as superabsorbent particles) that may be contained in the slurry. In one embodiment, the width of the headbox 80 can be increased over the length of the flow section 82 by an amount greater than about 10%, such as an amount greater than about 20%, such as an amount greater than about 50%, such as an amount greater than about 70%, such as an amount greater than about 120%, such as an amount greater than about 140%, such as an amount greater than about 180%, such as an amount greater than about 200%, and generally by an amount less than about 400%, such as an amount less than about 300%.

[0098] In one embodiment, the fiber slurry 76 experiences a hydraulic jump from the slicing zone 140 to the expansion zone 150. For example, a hydraulic jump may occur when a shallow, high-speed fluid encounters a slower moving fluid, causing a rapid dissipation of kinetic energy. For example, when a fluid at high speed is discharged into a lower velocity zone, a rather sudden rise may occur in the fluid surface. The fast-flowing fluid suddenly slows down and increases in height, which releases kinetic energy, causing turbulence and / or eddy formation. For example, under some conditions, the transition of the fluid from fast to slow causes the fluid to curl itself, which in the method of the present disclosure causes the fibers to experience intense mixing and redirection.

[0099] In one embodiment, the flow of the fiber slurry 76 reaches supercritical flow in the slicing zone 140 and then reaches subcritical flow in the expansion zone 150. Supercritical flow occurs when the flow is dominated by inertial forces rather than gravity, and can be manifested as fast or unstable flow. Supercritical flow has a Froude number greater than 1. On the other hand, subcritical flow is dominated by gravity and exhibits a slower stable mode. When the flow transitions from supercritical flow to subcritical flow, hydraulic jumps may occur, which indicates high energy loss, turbulence, and random orientation of fibers.

[0100] In one aspect of the present disclosure, the flow of the slurry 76 of fibers and optionally at least one other solid component through the slicing zone 140 can be operated at a desired Froude number. For example, the Froude number of the foamed fiber suspension can be greater than about 2, such as greater than about 5, such as greater than about 10, such as greater than about 15, such as greater than about 20, such as greater than about 25, such as greater than about 30, and generally less than about 50, such as less than about 40.

[0101] The next downstream zone (in the longitudinal direction 81) in the flow section 82 may be the formation zone 160. The bottom surface of the expansion zone 160 may be the formation surface 94. The formation zone 160 may have a starting height equal to the expansion height (t1). The height of the formation zone 160 may contract to a formation height (t2) as the slurry 76 flows in the longitudinal direction 81.

[0102] In an embodiment of the present subject matter, the top surface 120 and the bottom surface 110 can be adjusted relative to each other in the height direction 85. In this way, the initial height (t i ), slice height (t s), one or more of the expanded height (t1), and the formed height (t2). In another embodiment of the present subject matter, at least a portion of the top surface 120 or the bottom surface 110 can be flexible. In this way, the initial height (t2) can be adjusted independently by deflecting the flexible portion of the top surface 120 or the bottom surface 110 in the height direction 85. i ), slice height (t s ), one or more of the expanded height (t1) and the formed height (t2). In an embodiment, the flexible top surface 120 or the flexible bottom surface 110 can be a sheet or other similar structure.

[0103] The dimensions of the various features of the headbox 80 may vary depending on the particular application and desired results. In addition, the dimensions described above may be altered by adjusting various components in the system, such as by moving the top surface 120 relative to the bottom surface 110. For exemplary purposes only, in one embodiment, the slice height (t s ) is less than the initial height (t i ), such as less than about 50%, such as less than about 40%, such as less than about 30%, such as less than about 20%, such as less than about 10%, such as less than about 2%. Slice height (t s ) is usually larger than the initial height (t i ), such as greater than about 0.1%, such as greater than about 0.5%, such as greater than about 1%, such as greater than about 5%, such as greater than about 10%, such as greater than about 20%, such as greater than about 30%. Slice height (t s ) is typically less than about 60%, such as less than about 50%, such as less than about 40%, such as less than about 30%, such as less than about 25%, such as less than about 20%, such as less than about 15%, such as less than about 10%, of the expanded height (t1). s ) is typically greater than about 1%, such as greater than about 2%, such as greater than about 5%, such as greater than about 10%, such as greater than about 20%, such as greater than about 25%, such as greater than about 30%, such as greater than about 35%, such as greater than about 40%, of the expanded height (t1).

[0104] like Figure 6 As illustrated, the headbox may also include a top flow channel 170. The top flow channel may be arranged above the flow section (in the height direction 85). In an embodiment, the top flow channel 170 may deposit an additional layer on top of the resulting slurry 76 to form a multi-layer product or a laminated product. The additional layer may be the same material as the material used to make the resulting slurry 76, or may be another material, as desired.

[0105] In an embodiment of the present subject matter, the geometry of the flow segment 82 is adapted to maintain a high flow velocity of the slurry 76 relative to any stationary surface to avoid agglomeration and backflow of fibers or other solid components (such as superabsorbent particles) that may be contained in the slurry. For example, the geometry of the flow segment 82 in the transverse direction 83 may be as described in PCT Patent Application No. PCT / US2021 / 034722 (which is incorporated herein by reference in its entirety).

[0106] Reference again Figure 1 4, the apparatus 10, 110, 210 may also include a forming surface 94 on which the resulting slurry 76 is deposited after exiting the outlet 92 of the headbox 80. The forming surface 94 may be a porous sheet such as a woven belt or a screen, or any other suitable surface for receiving the resulting slurry 76. Figure 5 As shown, the forming surface 94 may be inclined relative to the horizontal plane. In some embodiments, the resulting slurry 76 may be located on another preformed substrate on top of the forming surface 94. The apparatus 10, 110 may also include a dewatering system 96, which may be configured to remove liquid from the resulting slurry 76 on the forming surface 94. In some embodiments, the dewatering system 96 may be configured to provide a vacuum to the resulting slurry 76 to extract liquid from the resulting slurry 76, and in doing so, the resulting slurry 76 containing a plurality of fibers 20 and components 44 may be converted into a substrate 12. In some embodiments, the apparatus 10, 110, 210 may also include a drying system 98. The drying system 98 may be configured to further dry the resulting slurry 76 and / or the substrate 12. In some embodiments, the apparatus 10, 110, 210 may include a winding system 99, which may be configured to wind the substrate 12 in a roll. In other embodiments, apparatus 10, 110, 210 may decorate substrate 12, or collect substrate 12 in any other suitable configuration.

[0107] Foaming fluid

[0108] The foam forming process as described herein may include a foaming fluid. In some embodiments, the foaming fluid may account for between about 85% and about 99.99% (by weight) of the foam. In some embodiments, the foaming fluid used to make the foam may include at least about 85% of the foam (by weight). In certain embodiments, the foaming fluid may account for between about 90% and about 99.9% (by weight) of the foam. In certain other embodiments, the foaming fluid may account for between about 93% and 99.5% of the foam, or even between about 95% and about 99.0% (by weight) of the foam. In a preferred embodiment, the foaming fluid may be water, however, it is conceivable that other processes may utilize other foaming fluids.

[0109] Foaming surfactant

[0110] The foam forming process as described herein can utilize one or more surfactants. Fibers and surfactants together with foaming liquid and any additional components can form a stable dispersion that can substantially maintain a high porosity for a longer time than the drying process. In this regard, surfactants are selected to provide foams with a foam half-life of at least 2 minutes, more preferably at least 5 minutes, most preferably at least 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 they provide 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 they are compatible) and more than one surfactant of the same type. For example, a combination of a cationic surfactant and a nonionic surfactant or a combination of an anionic surfactant and a nonionic surfactant can be used in some embodiments due to its compatibility. However, in some embodiments, combinations of cationic and anionic surfactants may not be satisfactorily combined due to incompatibility between the surfactants.

[0111] Anionic surfactants that are considered suitable for use in 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 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 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).

[0112] Cationic surfactants are also considered to be suitable for use with the present disclosure in some embodiments of making substrates. In some embodiments, such as those comprising superabsorbent materials, cationic surfactants may be less preferably used 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. The example of other cationic surfactants includes 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 the present disclosure include benzalkonium chloride, benzethonium chloride, cetrimonium bromide, distearyldimethylammonium chloride, tetramethylammonium hydroxide, and the like.

[0113] Nonionic surfactants that are considered suitable for use in 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 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.

[0114] 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 embodiments, the foaming surfactant may comprise between about 0.005% and about 5% (by weight) of the foam. In certain embodiments, the foaming surfactant may comprise between about 0.05% and 3% of the foam, or even between about 0.05% and about 2% (by weight) of the foam.

[0115] fiber

[0116] As described above, the apparatus 10, 110 and methods described herein may include providing fibers from a supply of fibers 18. In some embodiments, the fibers may be suspended in a fluid supply 16, 28, which may be a foam. The foam suspension of fibers may provide one or more fiber supplies. In some embodiments, the fibers used herein may include natural fibers and / or synthetic fibers. In some embodiments, the fiber supply 18 may include only natural fibers or only synthetic fibers. In other embodiments, the fiber supply 18 may include a mixture of natural fibers and synthetic fibers. Some of the fibers used herein may be absorbent, while other fibers used herein may be non-absorbent. Non-absorbent fibers may provide features to the substrate formed by the methods and apparatus described herein, such as improving the intake or distribution of fluids.

[0117] A wide variety of cellulosic fibers are considered suitable for use herein. In some embodiments, the fibers used may be conventional papermaking fibers, such as wood pulp fibers formed by various 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), etc. 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, etc. 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.

[0118] 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 embodiment, refined fibers are utilized in the tissue web, thereby allowing the total amount of virgin and / or high average fiber length wood fibers (such as softwood fibers) to be reduced.

[0119] Regardless of the source of the wood pulp fibers, the wood pulp fibers preferably have an average fiber length greater than about 0.2 mm and less than about 3 mm, such as about 0.35 mm and about 2.5 mm, or between about 0.5 mm and about 2 mm, or even between about 0.7 mm and about 1.5 mm.

[0120] In addition, other cellulose fibers that can be used for 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.

[0121] 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.

[0122] In some embodiments, non-wood and synthetic cellulose fibers can have a fiber length greater than about 0.2 mm, including, for example, having an average fiber size between about 0.5 mm and about 50 mm, or between about 0.75 mm and about 30 mm, or even between about 1 mm and about 25 mm. In general, when using relatively large average length fibers, it is generally advantageous to change the amount and type of foaming surfactant. For example, in some embodiments, if relatively large average length fibers are used, it may be beneficial to utilize a relatively higher amount of foaming surfactant to help achieve a foam with a desired foam half-life.

[0123] Other fibers that can be used in the present disclosure include fibers that are resistant to forming fluids, i.e., those fibers that are not absorbent and whose bending stiffness is substantially unaffected by the presence of forming fluids. As mentioned above, the forming fluid will generally include water. By way of non-limiting example, water-resistant fibers include fibers such as polymer fibers that 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 the present disclosure. In some embodiments, non-absorbent fibers can be recycled fibers, compostable fibers, and / or marine degradable fibers. In addition, highly cross-linked cellulose fibers without significant absorption properties may also be used herein. In this regard, due to their very low level of absorbency to water, water-resistant fibers do not experience significant bending stiffness changes when contacting aqueous fluids, and are therefore able to maintain an open composite structure when wetted. The fiber diameter of the fiber can contribute to improving the bending stiffness. For example, PET fibers have higher bending stiffness than polyolefin fibers in both dry and wet states. The higher the fiber denier, the higher the bending stiffness exhibited by the fiber. Water resistant fibers desirably have a water retention value (WRV) of less than about 1 and more desirably between about 0 and about 0.5. In certain aspects, it is desirable that the fibers, or at least a portion thereof, comprise non-absorbent fibers.

[0124] The synthetic and / or water resistant fibers may have a fiber length greater than about 0.2 mm, including, for example, having an average fiber size between about 0.5 mm and about 50 mm, or between about 0.75 mm and about 30 mm, or even between about 1 mm and about 25 mm.

[0125] In some embodiments, the synthetic and / or water-resistant fibers may have a curled structure to enhance the volume-generating capability of the foam-forming fiber substrate. For example, PET curled staple fibers may be able to generate a higher thickness (or result in a lower sheet density) than PET straight staple fibers having the same fiber diameter and fiber length.

[0126] In some embodiments, the total fiber content may be between about 0.01% and about 10% (by weight) of the foam, and in some embodiments between about 0.1% and about 5% (by weight) of the foam.

[0127] Binder

[0128] In some embodiments, fluid supply 16,28 may include a binder material. Binder materials that can be used for 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 embodiments, the binder material used herein can be in powder form, such as thermoplastic PE powder. Importantly, the binder may include a water-insoluble binder on a dry substrate. In certain embodiments, the latex used in the present disclosure may be cationic or anionic to facilitate application and adhere to the cellulose fibers that can be used herein. For example, it is considered that the latex that is suitable 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 polymers, nitrile polymers, and other suitable anionic latex polymers known in the art. Examples of such latex are described in US4785030 to Hager, US6462159 to Hamada, US6752905 to Chuang et al., etc. Examples of suitable thermoplastic binder fibers include, but are not limited to, single-component and multi-component fibers of thermoplastic polymers such as polyethylene having at least one relatively low melting point. In certain embodiments, polyethylene / polypropylene sheath / core staple fibers may be used. Binder fibers may have lengths consistent with those described above for synthetic cellulose fibers.

[0129] Binders in liquid form, such as latex emulsions, may comprise between about 0% and about 10% (by weight) of the foam. In certain embodiments, non-fiber binders may comprise between about 0.1% and 10% (by weight) of the foam, or even between about 0.2% and about 5%, or even between about 0.5% and about 2% (by weight) of the foam. Binder fibers, when used, may be added to the other components in proportion to achieve the desired fiber ratio and structure while keeping the total solids content of the foam below the above amounts. For example, in some embodiments, binder fibers may comprise between about 0% and about 50% of the total fiber weight, more preferably between about 5% and about 40% of the total fiber weight in some embodiments.

[0130] Foam stabilizer

[0131] In some embodiments, if the fluid supply 16, 28 is configured as a foam, the foam may also optionally include one or more foam stabilizers known in the art that are compatible with the components of the foam and, in addition, do not interfere with hydrogen bonding between the cellulose fibers. Foam stabilizers considered suitable for use in the present disclosure include, but are not limited to, one or more zwitterionic compounds, amine oxides, alkylated polyalkylene oxides, or mixtures or combinations thereof. Specific examples of foam stabilizers include, but are not limited to, coconut oil-based amine oxides, isononyl dimethyl amine oxides, n-dodecyl dimethyl amine oxides, and the like.

[0132] In some embodiments, if utilized, the foam stabilizer may comprise between about 0.01% and about 2% of the foam by weight. In certain embodiments, the foam stabilizer may comprise between about 0.05% and 1% of the foam, or even between about 0.1% and about 0.5% of the foam by weight.

[0133] Components

[0134] In the method as described herein, the foam formation process may include adding one or more components as additional additives to be incorporated into the substrate 12. For example, one additional additive that may be added during the formation of the substrate 12 as described herein may be a superabsorbent material (SAM). SAMs are typically provided in particulate form and, in certain aspects, may include polymers of unsaturated carboxylic acids or derivatives thereof. These polymers are typically made water-insoluble, but water-swellable, by crosslinking the polymers with difunctional or multifunctional internal crosslinking agents. These internally crosslinked polymers are at least partially neutralized and typically contain pendant anionic carboxyl groups on the polymer backbone that enable the polymer to absorb aqueous fluids, such as body fluids. Typically, the SAM particles are post-treated to crosslink the pendant anionic carboxyl groups on the surface of the particles. SAMs are 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 forces 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 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.

[0135] In some embodiments incorporating a SAM, the SAM may comprise between about 0% and about 40% of the foam (by weight). In certain embodiments, the SAM may comprise between about 1% and about 30% of the foam (by weight), or even between about 10% and about 30% of the foam (by weight).

[0136] Other additives may include one or more wet strength additives that may be added to the foam or fluid supply 16, 28 to help improve the relative strength of the ultra-low density composite cellulosic material. Such strength additives suitable for use in paper fiber and tissue manufacturing are known in the art. Temporary wet strength additives may be cationic, nonionic, or anionic. Examples of such temporary wet strength additives include PAREZTM 631NC and PAREZ(R) 725 temporary wet strength resins, which are cationic glyoxylated polyacrylamides available from Cytec Industries in West Paterson, NJ. These and similar resins are described in US Paterson, Coscia et al., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ., US Paterson, NJ.

[0137] Permanent wet strength agents comprising cationic oligomeric or polymeric resins may also be used in the present disclosure. Polyamide-polyamine-epichlorohydrin type resins, such as KYMENE 557H sold by Solenis, are the most widely used permanent wet strength agents and are suitable for use in the present disclosure. Such materials have been described in the following US3700623 to Keim, US3772076 to Keim, US3855158 to Petrovich et al., US3899388 to Petrovich et al., US4129528 to Petrovich et al., US4147586 to Petrovich et al., US4222921 to Van Eenam, etc. Other cationic resins include polyethyleneimine resins and aminoplast resins obtained by the reaction of formaldehyde with melamine or urea. In the manufacture of the composite cellulose product of the present disclosure, permanent and temporary wet strength resins may be used together. In addition, dry strength resins may also be optionally applied to the composite cellulose web of the present disclosure. Such materials may include, but are not limited to, modified starches and other polysaccharides such as cationic, amphoteric and anionic starches as well as guar and locust bean gums, modified polyacrylamides, carboxymethyl cellulose, sugars, polyvinyl alcohol, chitosan, and the like.

[0138] If used, such wet and dry strength additives may comprise between about 0.01% and about 5% of the dry weight of the cellulose fibers. In certain embodiments, the strength additives may comprise between about 0.05% and about 2% of the dry weight of the cellulose fibers, or even between about 0.1% and about 1% of the dry weight of the cellulose fibers.

[0139] Other additional components may also be added to the foam, provided they do not significantly interfere with the formation of highly expanded stable foam, hydrogen bonding between cellulose fibers, or other desired properties of the web. As an example, additional additives may 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 desired to impart or improve one or more physical or aesthetic properties. In certain embodiments, the composite cellulose web may include skin benefit agents such as, for example, antioxidants, astringents, conditioners, emollients, deodorants, topical analgesics, film formers, humectants, hydrotropes, pH adjusters, surface modifiers, skin care agents, etc.

[0140] When used, the various components desirably comprise less than about 2% by weight of the foam, more desirably less than about 1% by weight of the foam, and even less than about 0.5% by weight of the foam.

[0141] In some embodiments, the solids content, including the fibers or particles contained herein, desirably comprises no more than about 40% of the foam. In certain embodiments, the cellulose fibers may comprise between about 0.1% and about 5% of the foam, or between about 0.2% and about 4% of the foam, or even between about 0.5% and about 2% of the foam.

[0142] The methods and apparatuses 10, 110, 210 as described herein can be beneficial in forming one or more components of a personal care product. For example, in one embodiment, the substrate 12 described herein can be an absorbent core for an absorbent article such as, but not limited to, a diaper, an adult incontinence garment, or a feminine care product. The substrate 12 described herein can also be beneficial in other products such as, but not limited to, facial tissues, wipes, and towels.

[0143] Implementation plan:

[0144] Embodiment 1: A headbox, the headbox comprising a longitudinal direction, a transverse direction and a height direction, the headbox comprising at least one flow section, the at least one flow section comprising: a bottom surface; a top surface, the top surface being opposite to the bottom surface in the height direction; wherein the at least one flow section comprises in order in the longitudinal direction: i) a contraction zone; ii) a slicing zone; iii) an expansion zone; and iv) a forming zone, wherein the contraction zone has an initial height (t i ), and the height shrinks in the longitudinal direction to the slice height (t s ); wherein the slicing zone is in fluid communication with the downstream end of the contraction zone and has a slicing length (l) in the longitudinal direction s ) and in the slice length (ls ) is equal to the slice height (t s ) height; wherein the expansion zone is in fluid communication with the downstream end of the slicing zone and has a height equal to the slicing height (t s ) and the height expands to an expanded height (t1) in the longitudinal direction; and wherein the forming zone is fluidly connected to the downstream end of the expansion zone and has a starting height equal to the expanded height (t1), and the height contracts to a forming height (t2) in the longitudinal direction.

[0145] Embodiment 2: The headbox of Embodiment 1, wherein the bottom surface and the top surface are adjustable relative to each other.

[0146] Embodiment 3: The headbox of any of the preceding embodiments, wherein at least a portion of the top surface is flexible.

[0147] Embodiment 4: The headbox of any of the preceding embodiments, wherein the top surface comprises a sheet.

[0148] Embodiment 5: A headbox as described in any of the preceding embodiments, wherein the initial height (t i ), the slice height (t s ), one or more of the expansion height (t1) and the formation height (t2) are individually adjustable.

[0149] Embodiment 6: The headbox as described in any of the preceding embodiments further comprises at least one top flow channel, the at least one top flow channel being separated from the at least one flow segment in the height direction and arranged above the at least one flow segment.

[0150] Embodiment 7: The headbox of any of the preceding embodiments, wherein the at least one flow segment comprises a first flow segment and a second flow segment.

[0151] Embodiment 8: The headbox of any of the preceding embodiments, wherein the first flow segment and the second flow segment are spaced apart from each other in the transverse direction.

[0152] Embodiment 9: The headbox according to any of the preceding embodiments, wherein the bottom surface in the forming zone is a forming surface, and the forming surface is inclined relative to a horizontal plane.

[0153] Embodiment 10: A method for producing a web, comprising: depositing a fiber slurry into a contraction zone; flowing the fiber slurry from the contraction zone through a slicing zone and into an expansion zone, the fiber slurry having a fluid flow rate and the slicing zone having a height (t s ) and length (l s ), causing the fiber slurry to experience turbulence in the expansion zone; causing the fiber slurry to flow from the expansion zone into a forming zone, the slurry being transported on a moving forming surface; draining fluid from the fiber slurry through the forming surface in the forming zone to form an embryonic web; and drying the embryonic web.

[0154] Embodiment 11: The method of Embodiment 10, wherein the slicing region comprises a narrow groove extending along the width of the slicing region.

[0155] Embodiment 12: The method of any of the preceding embodiments, wherein the fiber slurry undergoes supercritical flow in the chipping zone.

[0156] Embodiment 13: The method of any of the preceding Embodiments, wherein the turbulent flow of the fiber slurry within the expansion zone creates eddies that cause changes in the orientation of the fibers in the slurry.

[0157] 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.

[0158] 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 as more particularly described 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 foregoing description is by way of example only and is not intended to limit the present invention as further described in such appended claims.

Claims

1. A headbox, the headbox comprising a longitudinal direction, a transverse direction and a height direction, the headbox comprising at least one flow section, the at least one flow section comprising: a bottom surface spaced apart from the top surface; and The at least one flow section comprises, in order in the longitudinal direction: i) Contraction zone; ii) Slice area; iii) expansion zone; and iv) formation zone, The contraction zone has an initial height (t i ), and the height shrinks along the longitudinal direction to the slice height (t s ); The slicing zone is fluidically connected to the downstream end of the contraction zone and has a slicing length (l s ) and in the slice length (l s ) is equal to the slice height (t s )’s height; The expansion zone is in fluid communication with the downstream end of the slicing zone and has a height equal to the slicing height (t s ), and the height expands along the longitudinal direction to an expanded height (t1); and The formation zone is in fluid communication with a downstream end of the expansion zone and has a starting height equal to the expansion height (t1), and the height contracts along the longitudinal direction to a formation height (t2).

2. The headbox of claim 1, wherein the contraction zone gradually contracts along the longitudinal direction.

3. The headbox of claim 1, wherein the height of the expansion zone gradually increases from the slicing zone toward the downstream.

4. The headbox according to claim 1, wherein the slice height (t s ) is less than about 70% of the expanded height (t1), such as less than about 50%, such as less than about 30%, such as less than about 20%, such as less than about 10%, such as less than about 5%, and greater than about 1%, such as greater than about 10%, such as greater than about 20%.

5. The headbox of claim 1, wherein the bottom surface and the top surface are adjustable relative to each other.

6. The headbox of claim 1 wherein at least a portion of the top surface is flexible.

7. The headbox of claim 1 wherein the top surface comprises a sheet.

8. The headbox according to claim 1, wherein the initial height (t i ), the slice height (t s ), one or more of the expansion height (t1) and the formation height (t2) are individually adjustable.

9. The headbox of claim 1, further comprising at least one top flow channel separated from the at least one flow section in the height direction and arranged above the at least one flow section.

10. The headbox of claim 1, wherein the at least one flow segment comprises a first flow segment and a second flow segment.

11. The headbox of claim 7, wherein the first flow segment and the second flow segment are spaced apart from each other in the transverse direction.

12. The headbox of claim 1, wherein the bottom surface in the forming zone is a forming surface, and the forming surface is inclined relative to a horizontal plane.

13. A method for producing a web, comprising: depositing a slurry of fibers and at least one other solid component into the contraction zone; The slurry of the fibers and at least one other solid component is caused to flow from the contraction zone through the slicing zone and into the expansion zone, the fiber slurry having a fluid flow rate and the slicing zone having a height (t s ) and length (l s ), so that the fiber slurry increases in velocity in the slicing zone and experiences turbulence in the expansion zone; causing a slurry of the fibers and at least one other solid component to flow from the expansion zone into a forming zone, the slurry being conveyed on a moving forming surface; expelling a fluid from said slurry of fibers and at least one other solid component through said forming surface in said forming zone to form an embryonic web; as well as The embryonic web is dried.

14. The method of claim 13, wherein the at least one other solid component comprises superabsorbent particles.

15. The method of claim 14, wherein the density of the superabsorbent particles contained in the formed web varies by no more than about 10% in the cross-direction of the web.

16. The method of claim 13, wherein the slice height (t s ) is less than about 70% of the expanded height (t1), such as less than about 50%, such as less than about 30%, such as less than about 20%, such as less than about 10%, such as less than about 5%, and greater than about 1%, such as greater than about 10%, such as greater than about 20%.

17. The method of claim 13, further comprising the step of depositing another layer of fibers onto the embryonic web to form a multi-layer sheet.

18. The method of claim 13, wherein the dicing region comprises a slot extending along a width of the dicing region.

19. The method of claim 13, wherein the slurry undergoes supercritical flow in the slicing area.

20. The method of claim 13, wherein the turbulent flow of the slurry within the expansion zone creates eddies that cause slurry mixing.

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