Headbox for making a base material

Abstract

Apparatuses and methods for producing a base material 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 contraction zone; a slice zone; an expansion zone; and a forming zone. A method for producing a web is also provided. The method can include depositing a fibrous slurry into a contraction zone. The fibrous slurry can then be caused to flow from the contraction zone through a slice zone and into an expansion zone. The fibrous slurry can then be caused to flow from the expansion zone into a forming zone. The slurry can be conveyed on a moving forming surface. Fluid can be expelled from the fibrous slurry through the forming surface within the forming zone to form an embryonic web. The embryonic web can be dried.

Description

Technical Field

[0001] This invention relates generally to apparatus and methods for forming substrates. More specifically, this disclosure relates to foam forming methods and apparatus for forming substrates. Background Technology

[0002] Personal care products, such as diapers, diaper pants, training pants, adult incontinence products, and feminine hygiene products, may include a variety of substrates. For example, diapers may include absorbent structures, nonwoven materials, and membranes. Similarly, facial tissues, wipes, and wipes may also include a variety of substrates. Some of the substrates in these products may include natural fibers and / or synthetic fibers. In some products, some substrates may also include different types of components to provide additional functionality to the substrate and / or the final product itself.

[0003] For example, one such component that might be desired to be added to a substrate includes superabsorbent material (SAM). SAM can be constructed in granular or fibrous form and is commonly used in substrates to increase absorbency. Absorbent systems in personal care absorbent products, such as diapers, typically include SAM. Processes exist for forming substrates with SAM, involving mixing SAM particles or fibers with cellulose fibers using a forming chamber to form an absorbent core. These processes are typically performed in a dry environment because SAM is difficult to handle when wet due to volume increase caused by absorbent fluids and gelation, as well as other potential drawbacks. However, alternative substrate forming processes can employ fluids, such as liquids, to form substrates that offer a variety of additional properties and efficiencies in terms of the manufacture and performance of such substrates.

[0004] To improve the various properties of thin paper webs, webs have been formed according to a foaming process. During the foaming process, a pulp of fibers is formed and spread onto a moving porous conveyor belt for use in the initial production of the web. Foam-formed webs can exhibit improvements in bulk, stretch, thickness, and / or absorbency.

[0005] Besides thin paper webs, foam forming can be used to manufacture all different types of webs and products. For example, relatively long fibers and synthetic fibers can be incorporated into webs using foam forming processes. Therefore, foam forming processes are more versatile than many wet web forming processes.

[0006] However, when webs are formed using foam forming processes, problems have arisen in controlling the fiber orientation in the resulting webs. For example, during web production, the foam suspends the fibers and transports them downstream at a flow rate exhibiting embolic flow characteristics and / or low yield stress. Consequently, many foam forming processes produce webs in which the fibers are primarily oriented in the longitudinal direction of the web manufacturing process, especially when the foam-formed web is formed on an inclined surface.

[0007] Therefore, there is a need for a system and method for producing foam-forming webs in which fiber orientation is controlled. Specifically, there is a need for a method and system for producing foam-forming webs in which fiber orientation is more random, and where fibers are oriented both longitudinally and transversely. Producing webs with a more uniform fiber orientation distribution can offer various benefits and advantages. For example, the web can exhibit greater uniformity in physical properties between the longitudinal and transverse directions. Improved headboxes for forming substrates also need to be developed. 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 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 formation zone. The contraction zone may have an initial height (t). i ), and this height can be reduced along the longitudinal direction to the slice height (t). s The slicing region can be fluidly connected to the downstream end of the contraction zone and can have a slicing length (l) in the longitudinal direction. s ) and in slice length (l s ) equal to the slice height (t) s The expansion zone can be fluidly connected to the downstream end of the slicing zone and can have a height equal to the slicing height (t). s The initial height of the expansion zone is t1, and this height can expand longitudinally to the expansion height (t1). The forming zone can be in fluid communication with the downstream end of the expansion zone and can have an initial height equal to the expansion height (t1), and this height can contract longitudinally to the forming height (t2).

[0009] In another embodiment, a method for producing webs 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 shrinkage zone. The fiber slurry is then able to flow from the shrinkage 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 This allows the fiber slurry to undergo turbulence within the expansion zone. The slurry can then flow from the expansion zone into the forming zone. The slurry can be transported across the moving forming surface. Fluid can be discharged from the fiber slurry through the forming surface within the forming zone to form the initial web. The initial web can then be dried.

[0010] Other features and aspects of this disclosure are discussed in more detail below. Attached Figure Description

[0011] The disclosure, which is comprehensive and enables the implementation of this disclosure, is set forth in more detail in the remainder of the specification and with reference to the accompanying drawings, in which:

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

[0013] Figure 2 Is it from Figure 1 The process diagram depicts a detailed schematic of the component feed system, two mixing joints, and two fluid supplies upstream of the headbox.

[0014] Figure 3 yes Figure 2 Cross-sectional view of the first mixing joint and outlet conduit of the component feeding system;

[0015] Figure 4A This is a process schematic diagram of an alternative exemplary method for introducing components into a fluid supply and forming a substrate comprising the components, according to another embodiment of this disclosure.

[0016] Figure 4B This is a process schematic diagram of another alternative exemplary method for introducing components into a fluid supply and forming a substrate comprising the components, according to another embodiment of this disclosure.

[0017] Figure 4C This is a process schematic diagram of another alternative exemplary method for introducing components into a fluid supply and forming a substrate comprising the components, according to another embodiment of this disclosure.

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

[0019] Figure 6 This is a side cross-sectional view of an exemplary headbox with a top flow channel.

[0020] The repeated use of reference numerals in this specification and drawings is intended to indicate the same or similar features or elements of this disclosure. Detailed Implementation

[0021] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this disclosure.

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

[0023] Each example is given illustratively and is not intended to be limiting. For example, a feature illustrated or described as part of one embodiment or drawing may be used in another embodiment or drawing to produce yet another embodiment. It is intended that this disclosure include such modifications and variations.

[0024] When describing elements of this disclosure or its preferred embodiments, the articles “a,” “an,” “the,” and “the” are intended to indicate the presence of one or more of that element. The words “comprising,” “including,” and “having” are intended to be inclusive, meaning that additional elements beyond those listed may be present. As used herein, the terms “first,” “second,” “third,” etc., do not specify a particular order but are used as a means of distinguishing different events when referring to the various features of this disclosure. Many modifications and variations may be made to this disclosure without departing from its spirit and scope. Therefore, the exemplary embodiments described herein should not be construed as limiting the scope of the invention.

[0025] definition

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

[0027] As used herein, the term “foam forming process” refers to a process used to manufacture products involving suspensions of mixtures comprising solids, liquids and dispersed bubbles.

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

[0029] As used in this article, the term "foam half-life" refers to the time elapsed until half of the initial foaming material has reverted to liquid water.

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

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

[0032] As used herein, unless otherwise expressly indicated, when used in relation to the composition of materials, the terms “percentage,” “%,” “weight percentage” or “weight %” each refer to the amount of a component as a percentage of the total amount by weight, unless otherwise expressly indicated.

[0033] The term "personal care absorbent articles" as used herein refers to articles intended or adapted to be placed close to or near the wearer's body (i.e., adjacent to the body) to absorb and contain various liquid, solid, and semi-solid excretions from the body. Examples include, but are not limited to, diapers, diaper pants, training pants, youth pants, swim trunks, feminine hygiene products (including but not limited to menstrual pads or pants), incontinence products, medical clothing, surgical pads, and bandages, etc.

[0034] The term "layer" refers to a discontinuous layer in a multi-layer product, where individual layers can be arranged side by side.

[0035] The terms “twisting,” “bonding,” or “joining” in this context refer to the joining, adhesion, connection, or attachment of two elements. When they are joined, adhered, connected, or attached to each other directly or indirectly, such as when each is directly bonded to an intermediate element, the two elements are considered twisted, bonded, or joined together. The twisting, bonding, or joining of one element to another can be achieved through 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 compositions thereof that, under most favorable conditions, are capable of absorbing at least about 10 times, at least about 15 times, or at least about 25 times their weight in an aqueous solution containing 0.9% by weight of sodium chloride.

[0037] As used herein, the term "longitudinal direction" refers to the direction of travel of the fibers deposited on the forming surface during the formation of a nonwoven web.

[0038] As used herein, the term "height direction" refers to the direction from the top surface of the flow section to the bottom surface and is perpendicular to the longitudinal direction defined above. As used herein, the term "lateral direction" refers to the direction perpendicular to both the longitudinal and height directions defined above.

[0039] As used in this article, the term "initial height" or "t" refers to... i "" refers to the distance between the top and bottom surfaces at the upstream part of the contraction zone.

[0040] As used in this article, the term "slice height" or "t" refers to... s "" refers to the distance between the top and bottom surfaces along the length of the sliced ​​area. The slice height is also the distance between the top and bottom surfaces at the downstream end of the contraction zone. The slice height is also the distance between the top and bottom surfaces at the upstream end of the expansion zone.

[0041] As used in this article, the term "slice length" or "l" refers to the length of a slice. s"" refers to the distance along the longitudinal direction that maintains the slice height.

[0042] As used herein, the term “expansion height” or “t1” refers to the distance between the top and bottom surfaces at the downstream portion of the expansion zone.

[0043] As used herein, the term “forming height” or “t2” refers to the distance between the top and bottom surfaces at the downstream portion of the forming zone.

[0044] As used herein, the term "pulp" refers to fibers derived 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, Spanish grass, milkweed, straw, jute, and bagasse. Pulp fibers can include hardwood fibers, softwood fibers, and mixtures thereof. As used herein, the term "average fiber length" refers to the average length of fibers, fiber bundles, and / or fibrous materials determined by measurement using microscopy. A sample of at least 20 randomly selected fibers is separated from a liquid suspension of the fibers. The fibers are placed on a microscope slide prepared to suspend the fibers in water. A staining dye is added to the suspended fibers to stain 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. Twenty fibers in the sample were measured using a 0-20 mil scale at 20X linear magnification, and the average length, minimum and maximum length, and deviation or coefficient of variation were calculated. In some cases, the average fiber length was calculated as a weighted average length of the fibers (e.g., fibers, fiber bundles, fibrous materials), determined using a Kajaani Fiber Analyzer model FS-200, for example, from Kajaani Oy Electronics, Kajaani, Finland. The sample was treated with an impregnation solution according to standard testing procedures to ensure the absence of fiber bundles or debris. Each sample was decomposed in hot water and diluted to a suspension of approximately 0.001%. When testing using standard Kajaani fiber analysis testing procedures, approximately 50 ml to 100 ml of test sample was drawn from each diluted suspension. The weighted average fiber length can be an arithmetic mean, a length-weighted mean, or a weight-weighted mean, and can be expressed by the following equation:

[0045]

[0046] Where k = maximum fiber length x i =fiber length n i=Number of fibers of length xi, n =Total number of fibers measured. A 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 length based on all different types (if any) of fibers in the sample.

[0047] As used herein, the term "short fiber" refers to discontinuous fibers made from synthetic polymers such as polypropylene, polyester, post-consumer recycled (PCR) fibers, nylon, etc., and those that are non-hydrophilic can be treated to become hydrophilic. Short fibers can be cut fibers, etc. Short fibers can have cross-sections such as round, bicomponent, multicomponent, molded, hollow, etc.

[0048] Generally, this disclosure relates to a method and system for forming nonwoven webs from a liquid or foam suspension of fibers and optionally at least one other solid component. The system and method of this disclosure utilize a uniquely and specially designed headbox that not only produces webs with a uniform but random fiber orientation, but also promotes the uniform distribution of another solid component (such as superabsorbent particles) that may be contained in the fiber slurry. The headbox design of this disclosure is particularly suitable for use in series with other similar headboxes to produce uniform nonwoven webs with uniform properties.

[0049] In one embodiment, the headbox design of this disclosure includes an initial contraction zone, which may be arcuate in height or in the Z-direction. The contraction zone terminates at a slicing zone forming a slot through which the slurry is fed. Following the slicing zone, the slurry enters an expansion zone whose height can gradually increase. The headbox is designed such that the velocity of the slurry increases as it passes through the slicing zone and then flows into the expansion zone, where turbulent mixing of the slurry occurs. In one aspect, the expansion zone following the slicing zone can induce a hydraulic jump, which randomly redirects the fibers in the slurry while uniformly binding the fibers with other solid components.

[0050] As the slurry travels from the shrinkage zone to the expansion zone, the width of the headbox can also expand laterally. For example, in one embodiment, the headbox may taper and increase in width along its entire length or at least along the length of the expansion zone. Thus, not only does the mixing of fibers and solid components occur as the slurry flows through the headbox, but the flow of the slurry also diffuses and increases the width. As described above, multiple headboxes can be placed in series to form a web across the entire width of the forming surface. This headbox design is particularly suitable for producing webs from a series of laterally spaced headboxes without any significant fiber inhomogeneity occurring at the convergence of slurry flows leaving the different headboxes.

[0051] In one embodiment, the headbox dimensions can be adjustable. For example, the top of the headbox can be movable toward and away from the bottom of the headbox. Thus, different headbox dimensions can be varied and controlled according to specific applications and based on the properties of the slurry. The headbox design of this disclosure maintains a high flow rate of the slurry relative to any stationary surface, thereby preventing agglomeration of fibers or solid components (such as superabsorbent particles) contained in the slurry. Overall, the flow disturbance generated by the headbox design provides randomization of the web fibers while diffusing the slurry flow without creating coaxial flow, which has caused problems in prior art systems.

[0052] Referring to the accompanying drawings, in one embodiment, this disclosure relates to a method and apparatus 10 for forming a substrate 12. Figure 1 A schematic diagram of an exemplary apparatus 10 is provided, which can be used as part of a foam forming process to manufacture a substrate 12 as a foam-forming product. Apparatus 10 may include a first tank 14 configured to maintain a first fluid supply 16. In some embodiments, the first fluid supply 16 may be foam. The first fluid supply 16 may include a fluid supplied by a fluid supply 18. In some embodiments, the first fluid supply 16 may include multiple fibers supplied by a supply of fibers 20; however, in other embodiments, the first fluid supply 16 may not contain multiple fibers. The first fluid supply 16 may also include a surfactant supplied 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, fibers (if present), and surfactant with air or some other gas to generate foam. The mixer 24 may also mix the foam with fibers (if present) to generate a foam suspension of fibers, wherein the foam holds and separates the fibers to promote fiber distribution within the foam (e.g., as an artificial product of the mixing process in the first tank 14). Uniform fiber distribution can promote the desired substrate 12, including, for example, visual appearance of strength and quality.

[0053] The device 10 may also include a second tank 26 configured to maintain a second fluid supply 28. In some embodiments, the second fluid supply 28 may be foam. The second fluid supply 28 may include a fluid supplied by a supply of fluid 30 and a surfactant supplied by a supply of surfactant 32. In some embodiments, the second fluid supply 28 may include multiple fibers in addition to or as a substitute for 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 surfactant with air or some other gas to generate foam.

[0054] For either or both of the first can 14 and the second can 26, the first fluid supply 16 or the second fluid supply 28 may function to form foam. In some embodiments, the foaming fluid and other components are functioned to form a porous foam with an air content greater than about 50% by volume and ideally greater than about 60% by volume. In some aspects, highly inflated foam is formed having an air content between about 60% and about 95%, and in other aspects, between about 65% and about 85%. In some embodiments, the foam may be functioned to introduce foam such that the expansion ratio (the volume of air in the expanded stable foam compared to other components) is greater than 1:1, and in some embodiments, the air:other component ratio may be between about 1.1:1 and about 20:1, or between about 1.2:1 and about 15:1, or between about 1.5:1 and about 10:1, or even between about 2:1 and about 5:1.

[0055] Foam can be generated by one or more means known in the art. Examples of suitable methods include, but are not limited to, vigorous mechanical agitation by mixers 24, 34, injection of compressed air, etc. Mixing components by using a high-shear, high-speed mixer is particularly suitable for forming the desired highly porous foam. Various high-shear mixers are known in the art and are considered suitable for use in this disclosure. High-shear mixers typically use a tank to hold the foam precursor and / or one or more conduits through which the foam precursor is guided. High-shear mixers may use a series of screens and / or rotors to process the precursor and result in vigorous mixing of the components and air. In a particular embodiment, a first tank 14 and / or a second tank 26 are provided, having one or more rotors or impellers and an associated stator. The rotors or impellers rotate at high speed to induce flow and shear. For example, air may be introduced into the tank at various locations or simply drawn in by the action of mixers 24, 34. While the specific mixer design may affect the speed required to achieve the desired mixing and shearing, in some embodiments, a suitable rotor speed 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 some embodiments, mixers 24, 34 may be operated with the foam until the eddies in the foam disappear or a sufficient volume increase is achieved, relative to a rotor-based high-shear mixer.

[0056] Additionally, 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-generating step or in consecutive foam-generating steps. 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 from which foam is formed. Alternatively, one or more individual components can be added to the foaming fluid to form an initial mixture (e.g., a dispersion or foam), and then the remaining components can be added to the initially foamed slurry, after which all components come into play to form the final foam. In this regard, fluid 18 and surfactant 22 can begin mixing and functioning to form the initial foam before any solids are added. If desired, fibers can then be added to the water / surfactant foam, which then further functions to form the final foam. Alternatively, fluid 18 and fiber 20 (such as high-density cellulose pulp) can be vigorously mixed at a high consistency to form an initial dispersion, followed by the addition of foaming surfactants, additional water, and other components (such as synthetic fibers) to form a second mixture, which is then mixed and acts to form foam.

[0057] The foam density for forming the first fluid supply 16 in the first tank 14 and / or the foam for forming the second fluid supply 28 in the second tank 26 can vary depending on the specific application and various factors, such as the fiber raw material used. In some embodiments, for example, the foam density 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 typically 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, lower density foams with typically less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L are used.

[0058] In some embodiments, the device 10 may further include a first pump 36 and a second pump 38. The first pump 36 may be in fluid communication with a 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 a 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, other suitable types of pumps are conceivable. Additionally, as further discussed below, in some embodiments, the device may be provided with a single pump that can pump a single fluid supply to both the first fluid supply 16 and the second fluid supply 28.

[0059] like Figure 1 and Figure 2 As shown, the device 10 may further include a component feeding system 40. The component feeding system 40 may include a component supply area 42 for receiving the supply of component 44, such as... Figure 2 The partial cross-section of the component supply region 42 is shown. The component feeding system 40 may also include an outlet conduit 46. The cross-sectional shape of the outlet conduit 46 may be circular or may be constructed in a rectangular form to form a slot. The component feeding system 40 may also include a hopper 48. The hopper 48 may be connected to the component supply region 42 and may be used to refill the component supply region 42 with the supply of component 44.

[0060] In some embodiments, the component feeding system 40 may include a solid volumetric pump. Examples of solid volumetric pumps that may be used herein may include systems utilizing screws / augers, belts, vibratory trays, rotary tables, or other known systems for handling and discharging the supply of component 44. Other types of feeders may be used in the component feeding system 40, such as batching feeders, such as those manufactured by Christy Machine & Conveyor, Fremont, Ohio. In some embodiments, the component feeding system 40 may also be configured as a conveying system.

[0061] The component feeding system 40 may also include a fluid control system 50. The fluid control system 50 may be configured to control gas entrainment into a 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 feeding system 40. In other embodiments, the fluid control system 50 may be formed as an integral part of the component feeding system 40 itself, making a separate housing 52 around the component feeding system 40 potentially unnecessary. Figure 1 and Figure 2 As shown, in some embodiments, the fluid control system 50 may also include a vent 54.

[0062] The supply of component 44 may be in the form of microparticles and / or fibers. In one embodiment described herein, the supply of component 44 may be in the form of superabsorbent material (SAM) in microparticle form. In some embodiments, SAM may be in the form of fibers. Of course, other types of components may also be considered for use in the apparatus 10 and method described herein, as further described below. The component feed system 40 described herein may be particularly advantageous for the supply of component 44 best suited for maintaining in a dry environment, with minimal exposure to the fluids or foams used in the apparatus 10 and method described herein.

[0063] refer to Figures 1 to 3In some embodiments, the device 10 and method described herein may include a first mixing connector 56 and a second mixing connector 58. In a preferred embodiment, the first mixing connector 56 may be an injector. The first mixing connector 56 may be in fluid communication with the outlet conduit 46 of the component feed system 40 and with a second fluid supply 28. Figure 3 As shown, the first mixing connector 56 may include a first inlet 60 and a second inlet 62. The first inlet 60 may be in fluid communication with the supply fluid of component 44 via an outlet conduit 46. The second inlet 62 may be in fluid communication with the second fluid supply 28. The first mixing connector 56 may also include a discharge port 64.

[0064] In a preferred embodiment, the first mixing connector 56 may be configured as a coaxial injector. For example, in a preferred embodiment, the first mixing connector 56 may be configured such that the first inlet axis 66 of the first inlet 60 of the first mixing connector 56 is coaxial with the outlet axis 68 of the outlet conduit 46 supplying the component 44. The first mixing connector 56 may also be configured such that the outlet axis 70 of the outlet 64 is coaxial with the outlet axis 68 of the outlet conduit 46. Therefore, the first mixing connector 56 may be configured such that the first inlet axis 66 of the first inlet 60 is coaxial with the outlet axis 70 of the outlet 64 of the first mixing connector 56. A second inlet 62 supplying the second fluid supply 28 to the first mixing connector 56 may be configured to enter the first mixing connector 56 from one side of the first mixing connector 56. This configuration, in which the supply of component 44 is delivered in the first inlet 60 in a manner coaxial with the discharge axis 70, rather than allowing the second fluid supply 28 to enter at the first inlet 60, is the opposite of most ejector configurations that use the prime mover of the fluid supply to mix the fluid supply and components, but provides the advantages of the first mixing joint 56 as described herein.

[0065] When configured as an ejector, the first mixing contact 56 mixes the supply of component 44 from the component feed system 40 with the second fluid supply 28. The second fluid supply 28 provides dynamic pressure to the supply of component 44 by diverting it at the second inlet 62 into and through the first mixing contact 56. This dynamic pressure can create a vacuum on both the supply of component 44 and the component feed system 40 to aid in drawing the supply of component 44, thereby mixing and entraining it in the second fluid supply 28. In some embodiments, the dynamic pressure can create a vacuum of less than 1.5 inHg on the supply of component 44; however, in other embodiments, the dynamic pressure can create a vacuum of 5 inHg or greater, or 10 inHg or greater, on the supply of component 44.

[0066] The fluid control system 50 can help manage the proper distribution and entrainment of component 44 supplied to the second fluid supply 28, and can 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 around the component feed system 40, additional fluid (e.g., ambient gas, such as air) may be entrained into the second fluid supply 28 when the supply of component 44 is metered into it. It is also possible that a vacuum pull on the supply of component 44 when the second fluid supply 28 generates dynamic pressure on the component feed system 40 may cause additional air to be entrained into the second fluid supply 28. In some cases, it may be desirable for additional air to be entrained 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 supplying component 44 to the second fluid supply 28 at the first mixing joint 56. For example, in some cases where the second fluid supply 28 is foam, the gas content in the foam may be desired to remain relatively constant as the foam passes through the first mixing joint 56. Therefore, the fluid control system 50 can help control the pressure on the component feed system 40 and the airflow through the component feed system, in order 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 counteract the supply of component 44 generated by the second fluid supply 28 and the dynamic pressure on the component feed system 40.

[0067] In some embodiments, the fluid control system 50 may include a sealed component feed system 40. For example, as discussed above, the fluid control system 50 may include a housing 52 to provide a seal on the component feed system 40. Sealing the component feed system 40 may 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.

[0068] However, in some embodiments, it may be beneficial for the fluid control system 50 to include additional capabilities. For example, in some embodiments, the fluid control system 50 may include a vent 54. The vent 54 may be configured to vent fluid flows (such as atmospheric airflow) to provide additional fluid flow control over the component feed system 40. The vent 54 may vent airflow (e.g., airflow) within the housing 52 to help control airflow and pressure surrounding the component feed system 40 within the housing 52. It has been found that by providing a vent 54 to introduce some large airflow into the component feed system 40, backflow of the second fluid supply 28 in the first mixing joint 56 can be reduced or eliminated. Reducing backflow of the second fluid supply 28 in the first mixing joint 56 can help prevent the component feed system 40 from becoming clogged or requiring cleaning, especially where the component feed system 40 may be delivering dried particles such as SAM. Under other process conditions, a completely sealed component feed system 40 may be desirable for similar reasons.

[0069] Additionally or alternatively, the fluid control system 50 may be configured to provide additional airflow (e.g., airflow) and / or positive pressure to prevent backfilling of the component feed system 40 under certain conditions, such as if downstream blockage occurs in the device 10 outside the first mixing joint 56. In the event of such blockage resulting in increased pressure, the second fluid supply 28 may be intended to backfill the component feed system 40. Backfilling fluid into the component feed system 40 can be detrimental to processing, especially if 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 can help prevent such backfilling.

[0070] It is also conceivable 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 as a substitute for venting air and / or the aforementioned positive pressure at the vent 54.

[0071] like Figure 3As shown, in some embodiments, the first mixing connector 56 may further include a Venturi section 72. The Venturi section 72 can be a necking region of the first mixing connector 56, which can increase the velocity of the second fluid supply 28 through the Venturi section 72, and thus increase the vacuum pressure generated 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, the distal end 74 of the outlet conduit 46 supplying component 44 to the first mixing connector 56 may 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 means of controlling the pressure of the second fluid supply 28 as it exits the first mixing connector 56 and the component feed system 40.

[0072] Compared to when the second fluid supply 28 enters the first mixing joint 56, the first mixing joint 56 also provides pressure control over the transfer of the second fluid supply 28, including component 44, as it exits the discharge port 64 of the first mixing joint 56. The second fluid supply 28 can be transferred at a second fluid pressure before the first mixing joint 56. The second fluid supply 28, including the component supplied from component 44, can exit the discharge port 64 of the first mixing joint 56 at a discharge pressure. The pressure difference between the second fluid pressure and the discharge pressure before the first mixing joint 56 can be controlled. In some embodiments, this pressure difference can be controlled by changing the flow rate of the second fluid supply 28. In some embodiments, this pressure difference can 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 further moved into the Venturi section 72, the area through which the second fluid supply 28 flows through the Venturi section 72 decreases, and therefore the supply pressure of the second fluid supply 28 increases. If the distal end 74 of the outlet conduit 46 is further removed from 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 therefore 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 and the discharge pressure before the first mixing junction 56 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.

[0073] Another feature of the first mixing joint 56, which can produce enhanced mixing and transfer of component 44 from the supply to the second fluid supply 28, is that a second inlet 62 providing the second fluid supply 28 is located upstream of the distal end 74 of the outlet conduit 46 that supplies 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, preventing any supply of component 44 from engaging or adhering to the inner surface of the first mixing joint 56. Therefore, in 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 connector 56, as well as the entry of the second fluid supply 28 into the upstream inlet of the first mixing connector 56, can create an annular fluid protection around the inlet of the supply of component 44, as it is encased in the second fluid supply 28 within the first mixing connector 56.

[0074] It should be noted that, although in Figures 1 to 3 The diagram shows a single outlet conduit 46 and a single first mixing connector 56 for the component feed system 40; however, it is conceivable that the outlet conduit 46 could split into two or more conduits to feed two or more first mixing connectors 56 for mixing the supply of component 44 with the second fluid supply 28. In this configuration, the second fluid supply 28 could include as many conduits as the first mixing connectors 56. By having more than one outlet conduit 46 and more than one first mixing connector 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, can be achieved.

[0075] In some embodiments, it is also conceivable that the first mixing connector 56 may be an injector of a different configuration, rather than a coaxial injector as described above. For example, it is conceivable that the first mixing connector 56 may be an injector shaped like a slot injector.

[0076] Refer again Figure 1In some embodiments, device 10 may include a second mixing connector 58. The second mixing connector 58 provides the function of mixing a second fluid supply 28, comprising components supplied from component 44, with a first fluid supply 16. The second fluid supply 28, comprising components supplied from component 44, can be transferred to the second mixing connector 58 as it exits the outlet 64 of the first mixing connector 56. The first fluid supply 16 may be delivered to the second mixing connector 58 by a first pump 36. The second mixing connector 58 can mix the first fluid supply 16 and any of its components (e.g., fluid 18, fiber 20, surfactant 22) with the second fluid supply 28 and any of its components (e.g., fluid 30, surfactant 32) and components supplied from component 44 to provide a resulting slurry 76. The resulting slurry 76 can be transferred from the second mixing connector 58 through the outlet 78 of the second mixing connector 58 to a headbox 80. In some embodiments, such as Figure 3 As shown, a gap may exist between the discharge port 78 of the second mixing connector 58 and the headbox 80. However, in other embodiments, the discharge port 78 of the second mixing connector 58 may be integrated with the headbox 80.

[0077] In one aspect, the discharge port 78 includes a plurality of tubes for injecting slurry into the headbox 80. Using multiple tubes can facilitate foam preservation. For example, multiple inlet tubes can help maintain the inlet fluid velocity into the headbox 80. For example, the system may include at least 2 tubes, at least 3 tubes, at least 4 tubes, at least 5 tubes, and fewer than about 30 inlet tubes, such as fewer than about 20 inlet tubes, such as fewer than about 15 inlet tubes.

[0078] Alternative embodiments of the apparatus 110 and method for forming substrate 12 are described in Figure 4A Unless otherwise stated in this document, Figure 4A With Figures 1 to 3 The device 10 and method have the same components. Figure 4A The device 110 includes only a first tank 14 for maintaining the first fluid supply 16. Figure 4A The apparatus 110 and method do not include a second tank 26 comprising a second fluid supply 28. The first fluid supply 16 may include the supply of fluid 18, the supply of fiber 20, and the supply of surfactant 22. The apparatus 110 may also include, as referenced above... Figures 1 to 3 The component feeding system 40, fluid control system 50, and mixing connector 56 are described. Based on this configuration, the first pump 36 can transfer the first fluid supply 16 to the first mixing connector 56. As previously described, the component feeding system 40 can transfer the supply of component 44 to the first mixing connector 56. In a preferred embodiment, the first mixing connector 56 can be an injector, and more preferably, as referred to... Figure 3The coaxial injector is shown. A first mixing connector 56 mixes the first fluid supply 16 with the components supplied from component 44 and provides the resulting slurry 76 discharged from the outlet 64 of the first mixing connector 56 and transferred to the headbox 80. In some embodiments, the outlet 64 of the first mixing connector 56 may be separate from the headbox 80; however, in some embodiments, the outlet 64 of the first mixing connector 56 may be integrated with the headbox 80. In some embodiments, the first fluid supply 16 may comprise fluid 18 and surfactant 22 to mix with the supply of component 44, thereby providing the resulting slurry 76, but without any fibers. In other embodiments, the first fluid supply 16 may comprise fluid 18, fibers 20, and surfactant 22 to mix with the supply of component 44, thereby providing the resulting slurry 76.

[0079] Figure 4B Another alternative embodiment of the apparatus 210 and method for forming substrate 12 is shown. Apparatus 10 may include a first pump 36 in fluid communication with a first fluid supply 16. The first fluid supply 16 may include a supply of fluid 18 and surfactant 22. The first fluid supply 16 may split at a joint 17. The first fluid supply 16 may continue through two control valves 23. The first fluid supply 16 may continue through one of the control valves 23 in a conduit 19 and toward a headbox 80. A supply of fiber 20 may be added to the first fluid supply 16 via control valve 23. Preferably, the supply of fiber 20 may be provided to the first fluid supply 16 in a fluid supply such as foam.

[0080] When the first fluid supply splits at connector 17, the first fluid supply 16 can be pumped through the second control valve 23 in conduit 21 toward the first mixing connector 56. The fluid supply in this conduit may be referred to as the second fluid supply 28. The second fluid supply 28 may comprise the supply of fluid 18 and surfactant 22 (i.e., from the first fluid supply 16). In some embodiments, such as Figure 4B As shown, the supply of fiber 20' is preferably added to the second fluid supply 28. Preferably, the supply of fiber 20' can be provided to the first fluid supply 16 in a fluid supply such as foam.

[0081] exist Figure 4BIn the illustrated embodiment, the supply of component 44 can be added to the second fluid supply 28 at the first mixing connector 56 as described above. Device 210 may include an output 65 of the first mixing connector 56, which includes component 44 downstream of the discharge port 64 of the first mixing connector 64. The fluid in the output 65 of the first mixing connector 56 and the supply of component 44 can provide a first input 67 into the headbox 80. The first fluid supply 16 can provide a second input 69 into the headbox 80. The first input 67 can be separated from the second input 69 into the headbox 80. For example, in some embodiments, the first input 67 including component 44 can be separated from the second input 69 by a height orientation separator 71 (also referred to as a sheet), and thus, when fluid supplies 16, 28 are diverted through the headbox 80 to provide the resulting slurry 76, fluid supplies 16, 28 can be separated from each other for at least a portion of the headbox 80. In doing so, the resulting slurry 76 can provide two distinct layers to provide a bilayer substrate 12.

[0082] Figure 4C Another alternative implementation is shown. Figure 4C Similar to Figure 2 The configuration described, however, in Figure 4C The configuration provides a vent 154 that provides a controlled fluid flow to the supply of component 44 after component 44 enters the outlet conduit 46 of the component feed system 40, but upstream of the first mixing joint 56. This configuration can supply fluid (e.g., liquid, gas, or foam) to the supply of component 44 to help control fluid entrainment within the second fluid supply 28 when the supply of component 44 mixes with the second fluid supply 28 in the first mixing joint 56. For example, in one embodiment, adding a foam flow to the vent 154 can help prevent additional gas (e.g., air) from being entrained in the supply of component 44 when it mixes with the second fluid supply 28.

[0083] Regardless of whether the equipment 10, 110, 210 and method used for transferring the resulting slurry 76 are as described herein, or another equipment and / or method, a headbox 80 may be provided to further transfer the resulting slurry 76 to form the substrate 12. Figures 5 to 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, in Figures 5 to 6 The resulting slurry 76 is not shown in the figure.

[0084] The headbox 80 may include at least one flow section 82. Figures 5 to 6 In the embodiment of the headbox 80 shown, the headbox 80 includes a flow section 82. For example... Figures 5 to 6 As illustrated, flow section 82 may include four zones in the longitudinal direction 81.

[0085] The upstream section of flow segment 82 (in the longitudinal direction 81) can be a contraction zone 130. The contraction zone 130 may have an initial height (t). i The height of the shrinkage zone 130 can shrink to the slice height (t) as the slurry 76 flows along the longitudinal direction 81. s The shrinkage 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 produce the arc shape of the side profile of the shrinkage zone 130. It is believed that the arc shape along the height direction 85 of the shrinkage zone 130 between the top surface 120 and the bottom surface 110 (together with the geometry of the shrinkage zone 130 in the plane defined by the longitudinal direction 81 and the transverse direction 83) can provide enhanced control over the flow of the resulting slurry 76 and can help reduce eddies or other turbulence in the flow of the resulting slurry 76 through the shrinkage zone, further enhancing the aforementioned advantages regarding the components supplied from component 44. For example, such an arc shape is believed to provide a more consistent basis weight and fiber orientation across the transverse direction 83 in the formed substrate 12, particularly when used in foam forming processes.

[0086] The next downstream region (in the longitudinal direction 81) in the flow section 82 can be a slice region 140. Slice region 140 can have a slice 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 slice region 140 (i.e., the slice length (l) s )) can be the same.

[0087] The next downstream region in flow section 82 (along the longitudinal direction 81) can be an expansion region 150. The expansion region can have a value equal to the slice height (t). s The initial height of the expansion zone 150. The height of the expansion zone 150 can expand to the expansion height (t1) as the slurry 76 flows in the longitudinal direction 81.

[0088] Fiber pulp 76 is forced through slicing zone 140. The slicing height (t) of slicing zone 140... s ) and slice length (l sThe velocity and flow rate of the fiber slurry 76 are rapidly increased. The fiber slurry 76 then exits the slicing zone 140 and is discharged into the expansion zone 150. The rapid increase in velocity followed by a significant decrease in velocity of the fiber slurry 76 causes significant turbulence in the expansion zone 150, resulting in fiber mixing. Through this process, the fiber orientation becomes significantly more random, compared to orientation only in the longitudinal direction 81. Therefore, the fiber orientation in the longitudinal direction 81 can be the same as or similar to the fiber orientation in the transverse direction 83. After leaving the slicing zone 140, the fiber slurry 76 is then discharged into the forming zone 160 to retain and lock in the fiber orientation. In this way, a web with physical properties in the longitudinal direction 81 that are very similar to those in the transverse direction 83 can be produced.

[0089] As explained above, the fiber slurry 76 is accelerated in terms of flow rate and velocity through the slicing zone 140 and then discharged into the expansion zone 150, which has an expanded volume, allowing the velocity and flow rate of the foamed fiber suspension to decrease rapidly, thereby inducing turbulence within the fluid and producing random fiber orientation. Turbulence refers to the flow of a foamed suspension in which the fluid experiences irregular fluctuations or mixing compared to laminar flow, where the fluid moves along a smooth path or in layers. For example, the foamed fiber suspension can experience turbulence within the expansion zone 150, resulting in the formation of fluid vortices and eddies, which significantly enhances the random distribution of fibers within the foam.

[0090] The width of the headbox 80 over the flow section 82 can be uniform or variable. 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 diffused to form a nonwoven web. It has been found that the headbox 80 is not only particularly suitable for producing a uniform but random fiber distribution, but also particularly suitable for producing a uniform distribution of other solid components that may be contained in the slurry, such as superabsorbent particles. In one embodiment, the width of the headbox 80 may increase over the length of the flow section 82 by an amount greater than about 10%, such as greater than about 20%, such as greater than about 50%, such as greater than about 70%, such as greater than about 120%, such as greater than about 140%, such as greater than about 180%, such as greater than about 200%, and generally by an amount less than about 400%, such as less than about 300%.

[0091] In one embodiment, the fiber slurry 76 undergoes a hydraulic jump from the slicing zone 140 to the expansion zone 150. A hydraulic jump can occur, for example, when a shallow, high-velocity fluid encounters a slower-moving fluid, resulting in a rapid dissipation of kinetic energy. For example, a fairly abrupt rise in the fluid surface can occur when a high-velocity fluid is discharged into a lower-velocity zone. The sudden deceleration and height increase of the rapidly flowing fluid releases kinetic energy, thereby causing turbulence and / or eddy formation. For example, under certain conditions, the transition from fast to slow velocity causes the fluid itself to coil, which in the method of this disclosure causes the fibers to undergo intense mixing and reorientation.

[0092] In one embodiment, the flow of the fiber slurry 76 reaches supercritical flow in the slicing zone 140 and subsequently subcritical flow in the expansion zone 150. Supercritical flow occurs when the flow is governed by inertial forces rather than gravity, and can exhibit either rapid or unstable flow. Supercritical flow has a Froude number greater than 1. Subcritical flow, on the other hand, is governed by gravity and exhibits a slower, more stable mode. A hydraulic jump may occur when the flow transitions from supercritical to subcritical, indicating high energy loss, turbulence, and random orientation of the fibers.

[0093] In one aspect of this disclosure, the slurry 76 of fibers and optionally at least one other solid component can be operated at a desired Froude number through the flow of the slicing zone 140. 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.

[0094] The next downstream zone in the flow section 82 (in the longitudinal direction 81) can be the forming zone 160. The bottom surface of the expansion zone 160 can be the forming surface 94. The forming zone 160 can have an initial height equal to the expansion height (t1). The height of the forming zone 160 can shrink to the forming height (t2) as the slurry 76 flows in the longitudinal direction 81.

[0095] In embodiments of this 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) can be adjusted by moving the top surface 120 and the bottom surface 110 relative to each other in the height direction 85. i ), slice height (t) sThe initial height (t1) can be one or more of the expansion height (t2) and the formation height (t3). In another embodiment of this subject matter, at least a portion of the top surface 120 or the bottom surface 110 may be flexible. In this way, the initial height (t1) can be adjusted individually 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 The flexible top surface 120 or the flexible bottom surface 110 may be a sheet or other similar structure.

[0096] The dimensions of different features of the headbox 80 can vary depending on the specific application and desired results. Additionally, the dimensions described above can be altered by adjusting different components of the system, such as by moving the top surface 120 relative to the bottom surface 110. For illustrative purposes only, in one embodiment, the slice height (t) s ) less than the initial height (t) i Approximately 60%, such as less than approximately 50%, such as less than approximately 40%, such as less than approximately 30%, such as less than approximately 20%, such as less than approximately 10%, such as less than approximately 2%. Slice height (t) s ) is usually greater than the initial height (t) i Approximately 0.1%, such as greater than approximately 0.5%, such as greater than approximately 1%, such as greater than approximately 5%, such as greater than approximately 10%, such as greater than approximately 20%, such as greater than approximately 30%. Slice height (t) s Typically less than approximately 60% of the expansion height (t1), such as less than approximately 50%, such as less than approximately 40%, such as less than approximately 30%, such as less than approximately 25%, such as less than approximately 20%, such as less than approximately 15%, such as less than approximately 10%. Slice height (t) s It is typically greater than about 1% of the expansion height (t1), 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%.

[0097] 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 multilayer or laminated product. The additional layer may, as needed, be the same material as the material used to manufacture the resulting slurry 76, or it may be a different material.

[0098] In embodiments of this subject matter, the geometry of the flow section 82 is adapted to maintain a high flow rate of 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 section 82 in the transverse direction 83 may be as described in PCT patent application number PCT / US2021 / 034722 (which is incorporated herein by reference in its entirety).

[0099] Refer again Figure 1 As shown in Figure 4, devices 10, 110, and 210 may further 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 tape or 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 a horizontal plane. In some embodiments, the resulting slurry 76 may be located on top of another pre-formed substrate on the forming surface 94. The apparatuses 10, 110 may also include a dewatering system 96 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, comprising multiple fibers 20 and component 44, may be transformed into substrate 12. In some embodiments, the apparatuses 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 substrate 12. In some embodiments, the apparatuses 10, 110, 210 may include a winding system 99 configured to wind the substrate 12 in a coil. In other embodiments, devices 10, 110, 210 may decorate substrate 12 or collect substrate 12 in any other suitable configuration.

[0100] foamed fluid

[0101] The foam forming process described herein may include a foaming fluid. In some embodiments, the foaming fluid may comprise between about 85% and about 99.99% of the foam (by weight). In some embodiments, the foaming fluid used to manufacture the foam may comprise at least about 85% of the foam (by weight). In some embodiments, the foaming fluid may comprise between about 90% and about 99.9% of the foam (by weight). In some other embodiments, the foaming fluid may comprise between about 93% and 99.5% of the foam, or even between about 95% and about 99.0% of the foam (by weight). In a preferred embodiment, the foaming fluid may be water; however, other processes are conceivable that may utilize other foaming fluids.

[0102] foaming surfactants

[0103] The foam forming process described herein can utilize one or more surfactants. The fibers and surfactants, together with the foaming liquid and any additional components, can form a stable dispersion that can maintain a substantially high porosity for a longer period than a drying process. In this regard, the surfactant is selected to provide a foam with a foam half-life of at least 2 minutes, more preferably at least 5 minutes, and most preferably at least 10 minutes. The foam half-life can be a function of surfactant type, surfactant concentration, foam component / solids level, and mixing capacity / 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 the desired level of foam stability. In this regard, the foaming surfactant can be selected from anionic, cationic, nonionic, and amphoteric surfactants, provided that they, alone or in combination with other components, provide the necessary foam stability or foam half-life. It should be understood that more than one surfactant can be used, including surfactants of different types (provided they are compatible) and more than one surfactant of the same type. For example, combinations of cationic and nonionic surfactants or combinations of anionic and nonionic surfactants can be used in some embodiments due to their compatibility. However, in some implementations, the combination of cationic and anionic surfactants may not be satisfactory due to incompatibility between the surfactants.

[0104] Anionic surfactants considered suitable for use in this 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, alkylbenzene sulfonic acids and their salts, dialkylbenzene disulfonic acids and their salts, dialkylbenzene sulfonic acids and their salts, alkylphenol sulfonic acids / condensed alkylphenol sulfonic acids and their salts, or mixtures or combinations thereof. Other examples of anionic surfactants considered suitable for use in this disclosure include alkali metal sulforicinates; sulfonated glycerol esters of fatty acids such as sulfonated monoglycerides of coconut oil; salts of sulfonated monovalent alcohol esters such as sodium oleylisethianate; metal soaps of fatty acids; amides of aminosulfonic acids, such as sodium salts of oleylmethyl taurine; sulfonated products of fatty acid nitriles, such as palmitonium sulfonate; alkali metal alkyl sulfates, such as sodium lauryl sulfate, ammonium lauryl sulfate, or triethanolamine lauryl sulfate; ether sulfates having alkyl groups having eight 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; and sodium, potassium, and amine salts of alkylnaphthalene sulfonic acids. Certain phosphate surfactants, including phosphate esters such as sodium lauryl phosphate ester, or those available under the trade name TRITON from Dow Chemical Company, are also considered suitable. A particularly desirable anionic surfactant is sodium dodecyl sulfate (SDS).

[0105] Cationic surfactants are also considered suitable for use in some embodiments of the manufacture of substrates in conjunction with this disclosure. In some embodiments, such as those including superabsorbent materials, the use of cationic surfactants may be less preferred due to potential interactions between the cationic surfactant and the superabsorbent material (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. Further examples of cationic surfactants include various fatty acid amines and amides and their derivatives, as well as 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 containing 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 their salts, such as trimethylammonium tallow chloride, dioctadecyldimethylammonium chloride, didodecyldimethylammonium chloride, dihexylammonium chloride, alkyltrimethylammonium hydroxide, dioctadecyldimethylammonium hydroxide, trimethylammonium tallow chloride, trimethylammonium hydroxide, methylpolyoxyethylene cocoyl ammonium chloride, and dipalmitylhydroxyethylmethylammonium sulfate; amide derivatives of amino alcohols, such as β-hydroxyethylstearamide; and amine salts of long-chain fatty acids. Other examples of cationic surfactants considered suitable for use in this disclosure include benzalkonium chloride, benzyl chloride, cetrimonium bromide, distearate dimethyl ammonium chloride, tetramethyl ammonium hydroxide, etc.

[0106] Nonionic surfactants considered suitable for use in this 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, condensates of ethylene oxide and propylene oxide, fatty acid alkanolamides, and fatty amine oxides. Various other examples of nonionic surfactants include stearyl alcohol, sorbitan monostearate, octyl glucoside, octaethylene glycol monododecyl ether, lauryl glucoside, cetyl alcohol, cocoamide MEA, glyceryl monolaurate, polyoxyethylene alkyl ethers such as polyethylene glycol long-chain (12-14C) alkyl ethers, polyoxyethylene sorbitan ethers, polyoxyethylene alkoxylated esters, polyoxyethylene alkylphenol ethers, ethylene glycol-propylene glycol copolymers, polyvinyl alcohol, alkyl polysaccharides, polyethylene glycol sorbitan monooleate, octylphenol ethylene oxide, etc.

[0107] The foaming surfactant can be used in different amounts as needed to achieve the desired foam stability and air content in the foam. In some embodiments, the foaming surfactant may comprise between about 0.005% and about 5% of the foam (by weight). In some embodiments, the foaming surfactant may comprise between about 0.05% and 3% of the foam, or even between about 0.05% and about 2% of the foam (by weight).

[0108] fiber

[0109] As described above, the apparatus 10, 110, and methods described herein may include supplying 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. A 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 and synthetic fibers. Some fibers used herein may be absorbent, while others may be non-absorbent. Non-absorbent fibers may provide characteristics to the substrate formed by the methods and apparatus described herein, such as improved fluid absorption or distribution.

[0110] A wide variety of cellulose fibers are considered applicable herein. In some embodiments, the fibers used may be conventional papermaking fibers, such as wood pulp fibers formed through various pulping processes, such as kraft pulp, sulfite pulp, bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemimechanical pulp (TMCP), etc. By way of example only, fibers and methods for preparing wood pulp fibers are disclosed in US4793898, US4594130, US3585104, US5595628, US5595628, and US5522967, etc., issued to Laamanen et al. Furthermore, the fibers may be any wood pulp with a high average fiber length, wood pulp with a low average fiber length, or mixtures thereof. Examples of suitable high average length pulp fibers include softwood fibers, such as, but not limited to, northern softwood, southern softwood, mahogany, 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.

[0111] Furthermore, if desired, secondary fibers derived from recycled materials, such as pulp from sources like newsprint, recycled paperboard, and office waste paper, can be used. In a particularly preferred embodiment, refined fibers are utilized in the tissue paper web, thereby reducing the total amount of virgin and / or high-average-fiber-length wood fibers (such as cork fibers).

[0112] 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.

[0113] In addition, other cellulose fibers that can be used in this disclosure include non-wood fibers. As used herein, the term "non-wood fiber" generally refers to cellulose fibers derived from the stems of non-woody monocotyledonous or dicotyledonous plants. Non-limiting examples of dicotyledonous plants that can be used to produce non-wood fibers include kenaf, jute, flax, and ramie. 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, Heitzperro, etc.), vines (bamboo, sisal, bagasse, etc.), and grasses (Miscanthus sinensis, Spanish grass, lemon, saba, switchgrass, etc.). In some other cases, non-wood fibers may be derived from aquatic plants such as water hyacinth, microalgae such as spirulina, and macroalgae such as red or brown algae.

[0114] Additionally, other cellulose fibers used to manufacture the substrates described herein may include synthetic cellulose fiber types formed by spinning, including rayon in all its types, and other fibers derived from viscose fibers or chemically modified cellulose, such as, for example, those available under the trade names LYOCELL and TENCEL.

[0115] In some embodiments, non-wood and synthetic cellulose fibers may have fiber lengths greater than about 0.2 mm, including, for example, average fiber dimensions 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. Generally, when using fibers with relatively large average lengths, it is often advantageous to vary the amount and type of foaming surfactant. For example, in some embodiments, if fibers with relatively large average lengths are used, it may be beneficial to utilize relatively higher amounts of foaming surfactant to help achieve a foam with the desired foam half-life.

[0116] Other fibers that can be used in this disclosure include fibers resistant to forming fluids, i.e., those that are non-absorbent and whose flexural stiffness is substantially unaffected by the presence of the forming fluid. As mentioned above, the forming fluid typically includes water. By way of non-limiting examples, water-resistant fibers include fibers such as polymer fibers comprising polyolefins, polyester (PET), polyamides, polylactic acid, or other fiber-forming polymers. Polyolefin fibers such as polyethylene (PE) and polypropylene (PP) are particularly suitable for this disclosure. In some embodiments, the non-absorbent fiber may be recycled fiber, compostable fiber, and / or marine-degradable fiber. Additionally, highly cross-linked cellulose fibers without significant absorption properties may also be used herein. In this regard, due to their very low level of water absorption, water-resistant fibers do not experience significant changes in flexural stiffness upon contact with an aqueous fluid and are therefore able to maintain an open composite structure when wetted. The fiber diameter can contribute to increased flexural stiffness. For example, PET fibers have higher flexural stiffness than polyolefin fibers, whether in a dry or wet state. The higher the fiber denier, the higher the flexural stiffness exhibited by the fiber. Water-resistant fibers ideally have a water retention value (WRV) of less than about 1, and more ideally between about 0 and about 0.5. In some respects, it is desirable that the fiber, or at least a portion thereof, comprises non-absorbent fibers.

[0117] Synthetic fibers and / or water-resistant fibers may have fiber lengths 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.

[0118] In some implementations, the synthetic and / or water-resistant fibers may have a crimped structure to enhance the volumetric generation capability of the fiber substrate in foam formation. For example, PET crimped short fibers may be able to generate greater thickness (or result in lower sheet density) compared to straight PET short fibers with the same fiber diameter and fiber length.

[0119] In some embodiments, the total fiber content may be between about 0.01% and about 10% of the foam (by weight), while in other embodiments it may be between about 0.1% and about 5% of the foam (by weight).

[0120] adhesive

[0121] In some embodiments, fluid supplies 16, 28 may comprise an adhesive material. Adhesive materials that can be used in this disclosure may include, but are not limited to, thermoplastic adhesive fibers, such as PET / PE bicomponent adhesive fibers, and water-compatible adhesives, such as latex. In some embodiments, the adhesive material used herein may be in powder form, such as thermoplastic PE powder. Importantly, the adhesive may comprise an adhesive that is insoluble in water on a dry substrate. In some embodiments, the latex used in this disclosure may be cationic or anionic to facilitate application and adhesion to cellulose fibers that may be used herein. For example, latexes considered suitable include, but are 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 latexes are described in US4785030, granted to Hager; US6462159, granted to Hamada; US6752905, granted to Chuang et al., etc. Examples of suitable thermoplastic binder fibers include, but are not limited to, single-component and multi-component fibers of at least one thermoplastic polymer with a relatively low melting point, such as polyethylene. In some embodiments, short polyethylene / polypropylene sheath / core fibers may be used. The binder fibers may have lengths consistent with those described above regarding synthetic cellulose fibers.

[0122] The binder, in liquid form, such as a latex emulsion, may comprise between about 0% and about 10% of the foam (by weight). In some embodiments, the non-fibrous binder may comprise between about 0.1% and 10% of the foam (by weight), or even between about 0.2% and about 5%, or even between about 0.5% and about 2% of the foam (by weight). The binder fibers may be added proportionally to the other components during use to achieve a desired fiber ratio and structure while keeping the total solids content of the foam below the amounts described above. For example, in some embodiments, the 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.

[0123] Foam stabilizer

[0124] In some embodiments, if the fluid supplies 16, 28 are configured as foam, the foam may optionally include one or more foam stabilizers known in the art, said foam stabilizers being compatible with the components of the foam and, additionally, not interfering with the hydrogen bonding between the cellulose fibers. Foam stabilizers considered suitable for this disclosure include, but are not limited to, one or more zwitterionic compounds, amine oxides, alkylated polyepoxides, or mixtures or combinations thereof. Specific examples of foam stabilizers include, but are not limited to, cocoyl amine oxide, isononyl dimethyl amine oxide, n-dodecyl dimethyl amine oxide, etc.

[0125] In some embodiments, if used, the foam stabilizer may comprise between about 0.01% and about 2% of the foam (by weight). In some 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).

[0126] Components

[0127] In the methods 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 such additional additive that may be added during the formation of the substrate 12 as described herein may be a superabsorbent material (SAM). SAM is typically provided in particulate form and, in some respects, may comprise a polymer of an unsaturated carboxylic acid or a derivative thereof. These polymers are typically made insoluble in water by crosslinking them with a difunctional or polyfunctional internal crosslinking agent, but water can swell them. These internally crosslinked polymers are at least partially neutralized and typically contain side-attached anionic carboxyl groups on the polymer backbone, which enable the polymer to absorb aqueous fluids, such as bodily fluids. Typically, the SAM particles are post-treated to crosslink the side-attached anionic carboxyl groups on the particle surface. SAM is manufactured using known polymerization techniques, ideally by gel polymerization in an aqueous solution. The product of this polymerization process is an aqueous polymer gel, i.e., a SAM hydrogel that is mechanically reduced in size to small particles, which is then dried using drying procedures and equipment known in the art. After the drying process, the resulting SAM particles are pulverized to the desired particle size. Examples of superabsorbent materials include, but are not limited to, those described in US7396584, Dodge et al., US7935860, Azad et al., US2005 / 5245393, Bergam et al., and Chang et al., WO2008 / 027488. Additionally, to aid processing, SAM can be treated to make the material temporarily nonabsorbent during foam formation and the formation of highly expanded foam. For example, in one aspect, SAM can 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 formed and the drying operation begins. Alternatively, to prevent or limit premature expansion during processing, SAM can be introduced into the process at a low temperature.

[0128] In some embodiments incorporating SAM, SAM may comprise between approximately 0% and approximately 40% of the foam (by weight). In some embodiments, SAM may comprise between approximately 1% and approximately 30% of the foam (by weight), or even between approximately 10% and approximately 30% of the foam (by weight).

[0129] Other additives may include one or more wet strength additives, which may be added to the foam or fluid supply 16,28 to help improve the relative strength of the ultra-low density composite cellulose material. Such strength additives suitable for papermaking fibers and tissue paper manufacturing are known in the art. Temporary wet strength additives may be cationic, nonionic, or anionic. Examples of such temporary wet strength additives include PAREZ™ 631 NC and PAREZ® 725 temporary wet strength resins, which are cationic glyoxylated polyacrylamides available from Cytec Industries, West Paterson, NJ. These and similar resins are described in US3556932, granted to Coscia et al., and US3556933, granted to Williams et al. Additional examples of temporary wet strength additives include dialdehyde starch and other aldehyde-containing polymers, such as those described in US6224714, US6274667, US6287418, and US6365667, etc., granted to Schroeder et al.

[0130] Permanent wet-strength agents comprising cationic oligomers or polymers may also be used in this disclosure. Polyamide-polyamine-epimercohydrin type resins, such as KYMENE 557H sold by Solenis, are the most widely used permanent wet-strength agents and are suitable for use in this disclosure. Such materials have been described in the following patents: US3700623, US3772076, US3855158, US3899388, US4129528, US4147586, and US4222921, all granted to Keim et al. Other cationic resins include polyethyleneimine resins and amino plastic resins obtained by reacting formaldehyde with melamine or urea. In the manufacture of the composite cellulose products of this disclosure, permanent and temporary wet-strength resins may be used together. In addition, dry-strength resins may optionally be applied to the composite cellulose web of this disclosure. Such materials may include, but are not limited to, modified starch and other polysaccharides such as cationic, amphoteric and anionic starch, as well as guar gum and locust bean gum, modified polyacrylamide, carboxymethyl cellulose, sugar, polyvinyl alcohol, chitosan, etc.

[0131] If used, such wet strength and dry strength additives may comprise between about 0.01% and about 5% of the dry weight of the cellulose fibers. In some 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.

[0132] Other additional components may also be added to the foam, provided they do not significantly interfere with the formation of a highly expandable, stable foam, hydrogen bonding between cellulose fibers, or other desired properties of the web. As examples, additional additives may include, as needed, one or more pigments, opacifiers, antimicrobial agents, pH adjusters, skin-beneficial agents, odor absorbers, fragrances, thermally expandable microspheres, foam particles (such as pulverized foam particles), etc., to impart or improve one or more physical or aesthetic properties. In some embodiments, the composite cellulose web may include skin-beneficial agents, such as, for example, antioxidants, astringents, conditioning agents, emollients, deodorants, topical analgesics, film-forming agents, humectants, water-soluble growth promoters, pH adjusters, surface modifiers, skin care agents, etc.

[0133] When used, the various components should ideally comprise less than about 2% (by weight) of the foam, more ideally less than about 1% (by weight), or even less than about 0.5% (by weight).

[0134] In some embodiments, the solid content, including fibers or microparticles as described herein, ideally accounts for no more than about 40% of the foam. In some embodiments, cellulose fibers may account for 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.

[0135] The methods and devices 10, 110, and 210 described herein can be beneficial for 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, diapers, adult incontinence clothing, or feminine hygiene products. The substrate 12 described herein can also be beneficial for use in other products, such as, but not limited to, facial tissues, wipes, and wipes.

[0136] Implementation plan:

[0137] Implementation Scheme 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 the bottom surface in the height direction; wherein the at least one flow section comprises, in the longitudinal direction, in sequence: 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 to the slice height (t) in the longitudinal direction. s ); wherein the slicing region is in fluid communication with the downstream end of the contraction region and has a slicing length (l) in the longitudinal direction.s ) and at the slice length (l s ) equal to the slice height (t) s The height of the expansion zone is equal to the downstream end of the slicing zone and has a height equal to the slicing height (t). s The initial height of the forming region is such that the forming region expands to an expanded height (t1) in the longitudinal direction; and the forming region is in fluid communication with the downstream end of the expanded region and has an initial height equal to the expanded height (t1), and the height contracts to a forming height (t2) in the longitudinal direction.

[0138] Implementation Scheme 2: The headbox as described in Implementation Scheme 1, wherein the bottom surface and the top surface are adjustable relative to each other.

[0139] Implementation Scheme 3: The headbox as described in any of the preceding implementation schemes, wherein at least a portion of the top surface is flexible.

[0140] Implementation Scheme 4: A headbox as described in any of the preceding implementation schemes, wherein the top surface comprises a sheet.

[0141] Implementation Scheme 5: A headbox as described in any of the preceding implementation schemes, wherein the initial height (t) i ), the slice height (t) s One or more of the expansion height (t1) and the formation height (t2) can be adjusted individually.

[0142] Implementation Scheme 6: The headbox as described in any of the preceding implementation schemes further includes at least one top flow channel, which is separated from the at least one flow section in the height direction and arranged above the at least one flow section.

[0143] Implementation Scheme 7: A headbox as described in any of the preceding implementation schemes, wherein the at least one flow section includes a first flow section and a second flow section.

[0144] Implementation Scheme 8: A headbox as described in any of the preceding implementation schemes, wherein the first flow section and the second flow section are spaced apart from each other in the transverse direction.

[0145] Implementation Scheme 9: A headbox as described in any of the preceding implementation schemes, wherein the bottom surface in the forming zone is a forming surface, and the forming surface is inclined relative to the horizontal plane.

[0146] Implementation Scheme 10: A method for producing webs, comprising: depositing a fiber slurry into a shrinkage zone; allowing the fiber slurry to flow from the shrinkage 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 The process involves causing the fiber slurry to undergo turbulence within the expansion zone; allowing the fiber slurry to flow from the expansion zone into the forming zone, the slurry being transported on a moving forming surface; discharging fluid from the fiber slurry through the forming surface within the forming zone to form an initial web; and drying the initial web.

[0147] Implementation Scheme 11: The method as described in Implementation Scheme 10, wherein the slice region includes a slot extending along the width of the slice region.

[0148] Implementation Scheme 12: The method as described in any of the preceding implementation schemes, wherein the fiber slurry undergoes supercritical flow in the slicing zone.

[0149] Implementation Scheme 13: The method as described in any of the preceding implementation schemes, wherein the turbulence of the fiber slurry within the expansion zone generates eddies, which cause a change in the orientation of the fibers in the slurry.

[0150] All relevant portions of the documents referenced in the specific implementation are incorporated herein by reference; any reference to any document should not be construed as an admission that it is prior art concerning the invention. In the event of any conflict between the meaning or definition of any term in this written document and any meaning or definition of a term in the documents incorporated by reference, the meaning or definition assigned to the term in this written document shall prevail.

[0151] These and other modifications and variations of the invention can be practiced by those skilled in the art without departing from the spirit and scope of the invention as more specifically described in the appended claims. Furthermore, it should be understood that aspects of the various embodiments may be interchanged, in whole or in part. Moreover, those skilled in the art will understand that the foregoing description is merely illustrative and is not intended to limit the invention further described in the appended claims.

Claims

1. A headbox, the headbox comprising a longitudinal direction, a transverse direction, and a height direction, wherein the longitudinal direction refers to the direction of travel of fibers deposited on the forming surface during the formation of a nonwoven web, the headbox comprising at least one flow section, the at least one flow section comprising: A bottom surface, which is spaced apart from a top surface; The height direction refers to the direction from the top surface to the bottom surface of the flow section and is perpendicular to the longitudinal direction; the lateral direction refers to the direction perpendicular to both the longitudinal and height directions. The at least one flow section comprises, in the longitudinal direction, in the following order: i) A contraction zone, the contraction zone having an initial height (t) i ), wherein the initial height (t) of the contraction zone i () refers to the distance between the top and bottom surfaces at the upstream part of the contraction zone; ii) A slicing region having a slicing height (t) s ), wherein the slice height (t) s () refers to the distance between the top and bottom surfaces along the length of the sliced ​​area; iii) An expansion region having an expansion height (t1), wherein the expansion height (t1) refers to the distance between the top surface and the bottom surface at the downstream portion of the expansion region; and iv) A forming region having a forming height (t2), wherein the forming height (t2) refers to the distance between the top surface and the bottom surface at the downstream portion of the forming region. The initial height (t) of the contraction zone i Shrink along the longitudinal direction to the slice height (t) s ); The slicing region is in fluid communication with the downstream end of the contraction region, and the slicing region has a slicing length (l) in the longitudinal direction. s ), wherein the slice length (l s ) refers to the distance along the longitudinal direction on which the slice height is maintained, the slice height (t) s ) along the entire slice length (l) of the sliced ​​area s They are the same; The expansion region is in fluid communication with the downstream end of the slicing region, and the expansion region has a height equal to the slicing height (t). s The expansion zone starts at the initial height of the expansion region, and the expansion zone expands along the longitudinal direction to the expansion height (t1); and The forming region is in fluid communication with the downstream end of the expansion region, and the forming region has an initial height equal to the expansion height (t1), and the initial height of the forming region contracts along the longitudinal direction to the forming height (t2).

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

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

4. The headbox as claimed in claim 1, wherein the slice height (t) s It is less than 70% of the expansion height (t1) and greater than 1%.

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 as claimed in 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) can be adjusted individually.

9. The headbox of claim 1, further comprising at least one top flow channel, the at least one top flow channel being 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 section comprises a first flow section and a second flow section.

11. The headbox of claim 10, wherein the first flow section and the second flow section are spaced apart from each other in the transverse direction.

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

13. A method for producing webs, comprising: A slurry containing fibers and at least one other solid component is deposited into the shrinkage zone; A slurry containing fibers and at least one other solid component flows from the shrinkage zone through the slicing zone and into the expansion zone, the fiber slurry having a fluid flow rate and the slicing zone having a slicing height (t). s ) and slice length (l s This causes the fiber slurry to increase in velocity in the slicing zone and experience turbulence in the expansion zone, wherein the slice height (t) s ) refers to the distance between the top and bottom surfaces along the length of the slice area, and the slice length (l) s () refers to the distance along the longitudinal direction on which the slice height is maintained; A slurry containing fibers and at least one other solid component is fed from the expansion zone into the forming zone, the slurry being conveyed on a moving forming surface; Fluid is discharged from the slurry containing fibers and at least one other solid component through the forming surface within the forming zone to form an initial web; as well as The initial fabric is then 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 web varies by no more than 10% in the transverse direction of the web.

16. The method of claim 13, wherein the slice height (t) s It is less than 70% of the expansion height (t1) and greater than 1%.

17. The method of claim 13, further comprising the step of depositing another layer of fibers on the initial web to form a multilayer sheet.

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

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

20. The method of claim 13, wherein the turbulence of the slurry within the expansion zone generates eddies, and the eddies cause slurry mixing.

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