METHOD AND SYSTEM FOR FOAM-FORMING WEB HAVING MULTIPLE DISCHARGES per FORMING ZONE

Abstract

A method and system for foam forming a web is disclosed. The foamed fiber suspension is fed to one or more forming zones sequentially positioned along an inclined forming surface. A plurality of corresponding discharge devices are positioned below the forming surface for discharging excess fluid from the newly formed web. The flow rate of fluid discharged from the web is controlled relative to the flow rate or pressure of the foamed fiber suspension fed to the forming zones.

Description

[0001] Cross-references to related applications

[0002] This application relates to and has priority to U.S. Provisional Patent Application No. 63 / 492,095, filed on March 24, 2023, which is incorporated herein by reference in its entirety for all purposes. Background Technology

[0003] Many tissue products, such as facial tissues, toilet paper, paper towels, and industrial wipes, are produced using a wet-laid process. Wet-laid webs are made by depositing an aqueous suspension of pulp fibers onto a shaped fabric and then removing the water from the newly formed web.

[0004] To improve the various properties of tissue paper webs, webs have also been formed using a foaming process. During the foaming process, a foamed fiber suspension is formed and spread onto a moving porous conveyor belt for initial web production. 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, controlling web formation in the past has been problematic. For example, fiber-containing foamed suspensions are three-phase mixtures comprising solids, gases, and liquids. The gas represents the compressible portion, while the liquid is relatively incompressible. Therefore, the volume of the foamed suspension changes when subjected to pressure or temperature variations. Furthermore, these suspensions function as non-Newtonian fluids, and their viscosity varies with shear rate. Due to at least these properties of foamed suspensions, controlling the behavior of the foamed suspension fed onto the porous forming surface during web formation can be difficult. Additionally, over- or under-draining of fluid from the web formed from the foamed suspension can subject the web to shear forces, leading to defects and irregularities. These problems can be exacerbated when attempting to form multilayer structures.

[0007] Therefore, there is a need for a system and process for producing foam-forming webs that allows for better control of web formation, as the process is subject to natural variations in method conditions that significantly affect fluid behavior. Additionally, there is a need for a system and process for producing multilayer foam-forming webs that can control the resulting web formation and layer mixing. Summary of the Invention

[0008] Generally, this disclosure relates to an improved method and system for forming webs from a foamed fiber suspension. More specifically, the method and system of this disclosure have been specifically designed to better control web formation. Generally, the system and method of this disclosure involve controlling the supply flow of the foamed fiber suspension to the headbox and combining this with controlling the discharge flow through the forming surface. During the method, the foamed fiber suspension is fed into the forming zone. According to this disclosure, in one aspect, multiple discharge devices can be positioned aligned with the forming zone to discharge excess fluid from the forming surface. Each discharge device can be controlled independently. In this way, the method and system of this disclosure can control the discharge of fluid and form a desired discharge profile. For example, the multiple discharge devices can operate independently and can be used not only to form a uniform fiber formation in the web but also to enhance fiber mixing within the web.

[0009] For example, in one aspect, the systems and methods of this disclosure can be used to form single-layer or multi-layer webs. Multiple discharge devices can be used to control mixing within and between each layer. In this way, the resulting multi-layer webs can have better mechanical properties and better absorption characteristics, while also preventing certain materials from migrating to the surface of the web in an undesirable manner.

[0010] In one aspect, this disclosure relates to a method for producing webs. The method includes flowing a foamed suspension of material into a forming zone. The foamed suspension is fed into the forming zone at a first flow rate. The foamed suspension of material fed into the first forming zone is deposited near at least one movable porous forming surface to form an initial web layer. In one aspect, only one layer of the initial web is fed into each forming zone. Excess fluid is discharged through the porous forming surface into a first discharge device and a second discharge device. The first and second discharge devices are positioned aligned with the first forming zone along at least one porous forming surface. During web formation, the flow rate of the discharged fluid discharged through the first discharge device and the flow rate of the discharged fluid discharged through the second discharge device are controlled. The initial web is then dried.

[0011] In one respect, in addition to two emission devices, the forming zone can be aligned with three emission devices, four emission devices, five emission devices, and typically less than ten emission devices (such as less than six emission devices, such as less than five emission devices).

[0012] In one aspect, the flow rates of the discharge fluid discharged through the first discharge device and the discharge fluid discharged through the second discharge device are controlled based on at least one characteristic of the flow of the foamed suspension of the material fed into the forming zone. At least one characteristic of the flow of the foamed suspension of the material may include the temperature, pressure, mass flow rate, volumetric flow rate, or density of the foamed suspension of the material. The flow rate of the discharge fluid discharged through the first discharge device may be controlled independently of the flow rate of the discharge fluid discharged through the second discharge device.

[0013] In one aspect, the first discharge device may be positioned upstream and adjacent to the second discharge device, and the flow rate of the discharge fluid discharged through the first discharge device may be greater than or less than the flow rate of the discharge fluid discharged through the second discharge device. In another aspect, the flow rates of the discharge fluid through the first and second discharge devices may be substantially the same. For example, the flow rates of the fluid through the first and second discharge devices may differ by no more than about 20%, such as no more than about 15%, such as no more than about 10%, such as no more than about 5%, such as no more than about 3%, such as no more than about 1%. For example, in one embodiment, the first and second discharge devices may comprise vacuum chambers that apply suction to the web being formed. The amount of suction through each discharge device can be controlled in a manner that produces the desired flow rate. Matching the flow rates between the first and second discharge devices can provide various advantages and benefits, including producing webs with better formation and / or more uniform properties.

[0014] When forming a multilayer web, the method may further include the step of flowing a foamed suspension of material to a second forming zone positioned adjacent to the first forming zone. The foamed suspension of material may be fed into the second forming zone at a second flow rate. The foamed suspension of material fed into the second forming zone may be deposited near at least one movable forming surface, such that a second layer of material is formed below or above the material deposited from the first forming zone near the forming surface to form the multilayer web. A third discharge device may be positioned aligned with the second forming zone. The flow rate of the discharge fluid discharged through the third discharge device may be controlled. The second forming zone may be positioned downstream of the first forming zone, and the first and second discharge devices may be positioned upstream of the formation of the second layer. Alternatively, the second forming zone may be positioned upstream of the first forming zone, and the first and second discharge devices may be positioned downstream of the formation of the second layer.

[0015] In yet another embodiment, the method may include the step of flowing a foamed suspension of material to a third forming zone positioned adjacent to one of the other forming zones. The foamed suspension of material may be fed into the third forming zone at a third flow rate. The foamed suspension of material fed into the third forming zone is deposited near at least one movable porous forming surface, such that a third layer of material is formed in the multilayer web. Discharge fluid at a given flow rate is discharged through a fourth discharge device positioned aligned with the third forming zone.

[0016] When the method includes a second forming zone or a third forming zone, each forming zone can be aligned with multiple discharge devices, such as between two and four discharge devices, and each discharge device can be independently controlled to control the discharge through the multilayer web.

[0017] In one aspect, the method may further include the step of flowing fluid to a sealing region. The sealing region may be positioned adjacent to and upstream of a first forming region. The fluid fed into the sealing region may be ejected onto a moving porous forming surface to suppress airflow in the upstream longitudinal direction. In one aspect, the fluid fed into the sealing region may be non-fibrous and may include a liquid, such as water, or may include a foaming fluid.

[0018] Fluid can also be drawn through the initial web in a suction zone adjacent to and downstream of one or more forming zones. The discharge flow rate of the foamed fiber suspension discharged through one or more forming zones can enter the suction zone. In one aspect, the discharge flow rate of the foamed fiber suspension discharged through one or more discharge devices can be controlled such that excess fluid from one or more forming zones enters the suction zone for the purpose of controlling the liquid and air mixture collected by the suction zone.

[0019] In one embodiment, the method is operated such that the flow rate of fluid through one or more discharge devices aligned with the forming zone is less than the flow rate of a foamed suspension of material fed into the corresponding forming zone.

[0020] In one aspect, the foamed fiber suspension can be individually pumped to each of one or more forming zones, such that the fluid pressure in each supply line to each forming zone can be controlled independently of the other forming zones. In another aspect, for example, the foamed fiber suspension is pumped to a first forming zone at a first pressure, and the flow rates of the discharged fluid discharged through a first discharge device and a second discharge device are controlled based on the first pressure. The flow rate of the discharged fluid discharged through the discharge devices can be independently monitored by flow meters and pressure monitoring devices downstream of each discharge device on the forming surface. The flow meters and pressure monitoring devices can transmit information to a controller that calculates the discharge flow rate at a reference pressure or flow rate. The controller (which can be any suitable microprocessor or programmable device) can communicate with adjustable flow control devices for controlling the flow rates of the discharged fluid discharged through the first discharge device and the second discharge device based on the calculated discharge flow rate. For example, each flow control device can be an adjustable valve.

[0021] In one embodiment, the moving forming surface is operated at an angle relative to a horizontal plane. For example, the angle of the forming surface relative to the horizontal plane may be greater than about 10°, such as greater than about 20°, and typically less than about 60°, such as less than about 50°.

[0022] The web can be manufactured to have high bulk or low bulk characteristics. For example, the web can have a bulk greater than about 3 cc / g, such as greater than about 5 cc / g, such as greater than about 7 cc / g, such as greater than about 9 cc / g, such as greater than about 11 cc / g, such as greater than 14 cc / g, and generally less than about 20 cc / g. Alternatively, the web can have a bulk less than about 3 cc / g, such as less than about 1 cc / g, such as less than about 0.5 cc / g, such as less than about 0.08 cc / g, and generally greater than about 0.03 cc / g.

[0023] Webs manufactured according to this disclosure can have all different types of basis weights. For example, the basis weight can be from about 6 gsm to about 800 gsm, such as from about 10 gsm to about 200 gsm, such as from about 20 gsm to about 120 gsm. The web can be made solely of pulp fibers, or it can be made from pulp fibers mixed with other fibers (such as synthetic fibers and / or superabsorbent particles or fibers). Synthetic fibers can, for example, be present in the tissue web in an amount greater than about 5% by weight, such as greater than about 15% by weight, such as greater than about 20% by weight, such as greater than about 25% by weight, and at most 100% by weight. Synthetic fibers can include polymer fibers, such as polyester fibers. Alternatively, synthetic fibers can include regenerated cellulose fibers, such as rayon fibers, viscose fibers, etc.

[0024] According to this disclosure, a foamed fiber suspension can be formed by combining foam with fiber ingredients. The foam can have a density of about 200 g / L to about 600 g / L, such as about 350 g / L to about 600 g / L. The foamed suspension can be formed by combining a foaming agent with water. The foamed fiber suspension can contain about 40 vol% to about 80 vol% air, such as about 40 vol% to about 65 vol% air.

[0025] This disclosure also relates to a system for producing webs. The system includes a forming zone positioned relative to at least one porous forming surface. The forming zone is in communication with a foamed fiber supply line. The foamed fiber supply line includes a pumping device for flowing a foamed suspension of material to the corresponding forming zone. The foamed fiber supply line also includes a flow meter, a pressure monitoring device, a temperature monitoring device, or a combination thereof. The foamed fiber supply line is used to feed the foamed suspension of material into the corresponding forming zone to deposit the material contained in the foamed suspension onto the vicinity of at least one porous forming surface at a defined flow rate, pressure, or both. The system also includes a first discharge device positioned relative to the at least one porous forming surface and aligned with the forming zone. The first discharge device is in fluid communication with a first corresponding discharge line. The system also includes a second discharge device adjacent to the first discharge device and also positioned aligned with the forming zone, the second discharge device being in fluid communication with a second corresponding discharge line.

[0026] In one aspect, the first discharge line includes a first flow control device for controlling the flow rate of fluid discharged into the first discharge device. The first discharge line also includes a first flow meter, a first pressure monitoring device, a first temperature monitoring device, or a combination thereof. The second discharge line includes a second flow control device for controlling the flow rate of fluid discharged into the second discharge line. The second discharge line also includes a second flow meter, a second pressure monitoring device, a second temperature monitoring device, or a combination thereof. The system also includes one or more controllers that communicate with the flow control devices associated with the first and second discharge lines. The one or more controllers are configured to control the flow rate of fluid discharged into the first and second discharge devices relative to the flow rate or pressure of the foamed suspension of material fed into the forming zone.

[0027] In one aspect, for forming a multilayer web, the system includes multiple forming zones. Each forming zone is connected to a separate foam fiber supply line. Each foam fiber supply line includes a pumping device for flowing a foamed suspension of material to the corresponding forming zone. Each foam fiber supply line also includes a flow meter, a pressure monitoring device, a temperature monitoring device, or a combination thereof. Each foam fiber supply line is used to feed a foamed suspension of material into the corresponding forming zone to deposit the material contained in the foamed suspension onto at least one porous forming surface at a defined flow rate, pressure, or both. Each forming zone forms a single layer in the multilayer web.

[0028] For each forming zone, there is at least one corresponding discharge device. Each forming zone may include a single discharge device or multiple discharge devices. For example, each forming zone may include two, three, or four discharge devices. Each discharge device may be in fluid communication with a corresponding discharge line. Each discharge line includes a flow control device for controlling the flow rate of fluid discharged into each corresponding discharge device. Each discharge line also includes a flow meter, a pressure monitoring device, a temperature monitoring device, or a combination thereof.

[0029] One or more controllers may communicate with each of the flow control devices associated with the discharge line. One or more controllers may be configured to independently control the flow rate of fluid discharged to each discharge device relative to the flow rate or pressure of the foamed suspension of material fed into each forming zone of the forming zone.

[0030] As described above, each forming zone in the system can be aligned with two or more emission devices. In one aspect, the forming zone may have a length, and at least one of the emission devices aligned with the forming zone may extend beyond the length of the forming zone. For example, the emission device may extend beyond the length of the forming zone by less than about 20%, such as less than about 15%, such as less than about 10%, such as less than about 5%. In an alternative embodiment, all of the multiple emission devices aligned with the forming zone are positioned within the length of the forming zone.

[0031] In one embodiment, the system may further include a drying device positioned downstream of the forming zone for drying the web formed on the porous forming surface.

[0032] In one embodiment, the system may further include a separation tank in fluid communication with each of the discharge lines to receive discharge fluid from each discharge device. The separation tank can separate free gas from the foam and can be configured to recycle the foam in the production of a larger quantity of foamed fiber suspension. In one embodiment, the system may further include a suction zone adjacent to and downstream of a plurality of forming zones for suctioning air through the web formed on the forming surface. The flow rate of the fluid discharged from each discharge device may be controlled by one or more controllers, thereby causing the suction zone to collect a mixture of liquid and air from the web being formed. The liquid and air mixture collected from the suction zone may also be fed into the separation tank.

[0033] Other features and aspects of this disclosure are discussed in more detail below. Attached Figure Description

[0034] The full and achievable disclosure of this invention is set forth in more detail in the remainder of the specification (including reference to the accompanying drawings), in which:

[0035] Figure 1 This is a schematic diagram of one embodiment of a process for forming a web from a foamed fiber suspension according to the present disclosure;

[0036] Figure 2 This is a schematic diagram of a system and process for depositing a foamed fiber suspension onto a shaped surface according to the present disclosure;

[0037] Figure 3 This is a schematic diagram of another embodiment of the system and process for depositing a foamed fiber suspension onto a shaped surface according to the present disclosure;

[0038] Figure 4 This is a schematic diagram of another embodiment of the system and process for depositing a foamed fiber suspension onto a shaped surface according to the present disclosure;

[0039] Figure 5 This is a schematic diagram of another embodiment of the system and process for depositing a foamed fiber suspension onto a shaped surface according to the present disclosure;

[0040] Figure 6 This is a schematic diagram of another embodiment of the system and process for depositing a foamed fiber suspension onto a shaped surface according to the present disclosure;

[0041] Figure 7 This is a schematic diagram of another embodiment of the system and process according to the invention for depositing a foamed fiber suspension onto a molded surface; and

[0042] Figure 8This is a cross-sectional view of one embodiment of the forming zone that can be used in the process and system of this disclosure.

[0043] The repeated use of reference numerals in this specification and the accompanying drawings is intended to indicate the same or similar features or elements of the invention.

[0044] definition

[0045] As used herein, the term "foam-formed product" means a product formed from a suspension of a mixture comprising solids, liquids and dispersed bubbles.

[0046] 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.

[0047] 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.

[0048] As used in this article, the term "foam half-life" refers to the time elapsed until half of the initial foam material has reverted to liquid water.

[0049] 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.

[0050] 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).

[0051] 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.

[0052] 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.

[0053] 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.

[0054] As used herein, the term "longitudinal" refers to the direction of travel of the shaped surface on which the fibers are deposited during the formation of the nonwoven web.

[0055] As used in this article, the term "lateral" refers to a direction perpendicular to the longitudinal direction as defined above.

[0056] 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, hemp, and bagasse. Pulp fibers can include hardwood fibers, softwood fibers, and mixtures thereof.

[0057] As used herein, the term "average fiber length" refers to the average length of a fiber, fiber bundle, and / or fibrous material determined by measurement using microscopic techniques. A sample of at least 20 randomly selected fibers was isolated from a liquid suspension of the fibers. The fibers were placed on a microscope slide prepared to suspend the fibers in water. A staining dye was added to the suspended fibers to color the cellulose-containing fibers so that they could be distinguished or separated from synthetic fibers. The slide was placed under a Fisher Stereomaster II microscope—S19642 / S19643 series. The 20 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 is calculated as a weighted average length of the fibers (e.g., fibers, fiber bundles, fibrous materials), determined using, for example, a Kajaani Fiber Analyzer model FS-200 from Kajaani OyElectronics, Kajaani, Finland. The sample is treated with an impregnation solution according to a standard testing procedure to ensure the absence of fiber bundles or debris. Each sample is decomposed and diluted in hot water to a suspension of approximately 0.001%. When testing using the standard Kajaani fiber analysis testing procedure, approximately 50 ml to 100 ml of test sample is 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:

[0058]

[0059] in

[0060] k = Maximum fiber length

[0061] x i = Fiber length

[0062] n i = Number of fibers of length xi

[0063] n = the total number of fibers measured.

[0064] 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.

[0065] 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. Detailed Implementation

[0066] 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.

[0067] Generally, this disclosure relates to a system and process for forming webs, particularly nonwoven webs comprising tissue webs, absorbent cores, synthetic fiber pads, etc. According to this disclosure, the web is formed from a foamed fiber suspension. According to this disclosure, the supply and discharge flows of the foamed fiber suspension deposited on a porous forming surface can be controlled. For example, the web manufacturing system of this disclosure includes at least one discrete forming zone located adjacent to the forming surface, the at least one discrete forming zone receiving the foamed fiber suspension flow. The input pressure and / or input flow rate of the foamed fiber suspension entering the at least one discrete forming zone can be coordinated with the discharge flow through the porous forming surface to control the forming of the web. When producing multilayer webs, this process and system can result in layer mixing to produce multilayer webs with enhanced physical properties.

[0068] One or more discharge devices can be used to control the discharge flow through the porous forming surface. In one aspect, a single discharge device is positioned aligned with each corresponding forming zone. However, in another aspect, various advantages and benefits are obtained if more than one discharge device is positioned aligned with a single forming zone. Aligning multiple discharge devices with the forming zones allows for better control of fluid discharge. Generally, using multiple discharge devices for larger-scale discharge removes moisture from the web being formed and reduces the energy cost of subsequent web drying. For example, placing multiple discharge devices opposite the forming zones can remove significant amounts of moisture, especially from the superabsorbent material. For instance, reducing the amount of interstitial water in layers containing superabsorbent material can positively influence the web forming characteristics and significantly reduce the energy required to dry the web.

[0069] Controlling the flow of fluid through a porous forming surface using multiple discharge devices can also achieve control over fiber mixing. For example, in the production of single-layer webs, desired fiber mixing can be achieved within the layer. In the production of multi-layer webs, fluid discharge can be controlled to allow mixing between different layers of the web without sacrificing overall uniformity. For example, in one aspect, this process and system can be used to produce multi-layer webs comprising multiple discrete web forming zones that can be positioned adjacent to each other along a porous forming surface. During the formation of multi-layer webs, the discharge flow rate of each discrete forming zone can be controlled to produce webs with stable sheet forming and enhanced structural and interfacial stability.

[0070] In one aspect, the foamed fiber suspension is supplied to a headbox containing at least one discrete forming zone, and the discharge flow from the headbox can be converted into pressure for optimizing sheet formation. Through the processes and systems of this disclosure, the forming conditions of the web are controlled to avoid under-discharge and / or over-discharge during variations in process conditions and raw material inputs. In one embodiment, adjustable flow control devices (such as valves and / or pumps, including vacuum devices) are used to control the discharge flow from the porous forming surface, these adjustable flow control devices being controlled by volumetric flow meters and / or pressure transmitters and / or temperature monitoring devices. The combination of flow meters, pressure transmitters, and / or temperature monitoring devices allows for a fully quantified two-phase discharge flow profile, which can then be converted to a reference value. In this way, the adjustable flow meter device can be controlled to achieve the calculated discharge flow rate at the reference value.

[0071] The systems and processes disclosed herein offer various advantages and benefits. For example, fiber orientation and / or fiber blending can be controlled during the process. Therefore, the systems and processes disclosed herein can also be used to produce webs with customized properties for a specific end use. For example, webs with improved tensile properties, improved absorption properties, increased bulk (if desired), increased thickness (if desired), and / or increased basis weight can be formed using the processes disclosed herein. Furthermore, combinations of different properties can be enhanced and improved.

[0072] In addition to the above, the systems and processes disclosed herein minimize any adverse effects that may arise from applying vacuum or suction to the foamed fiber suspension or the initial web being formed. Overall, the coordinated input pressure and exhaust flow across multiple forming zones enables stable sheet formation.

[0073] As described above, the process and system of this disclosure are particularly suitable for foam forming processes used in the production of fiber webs. The foam forming process described above offers numerous advantages and benefits. In this process, foam is used instead of water as the carrier for the fibers forming the web. The foam (which represents a large amount of air) is blended with the fibers and optionally other materials such as superabsorbent materials. Because less water is used to form the web, less energy is required to dry it.

[0074] While foam formation processes and systems offer various advantages, controlling the foamed suspension during the production of webs is problematic. For example, a foamed suspension is a two-phase system comprising a compressible gas phase and a substantially incompressible liquid phase. Because foamed suspensions are non-Newtonian fluids, the density and viscosity of the foam vary depending on location and process. According to this disclosure, various parameters of the foamed suspension can be monitored or calculated during the process to determine its characteristics as it is deposited onto the forming surface and as the fluid exits from the forming surface. For example, the flow rate of the foamed suspension fed onto the forming surface, such as volumetric flow rate, pressure, temperature, and / or density, can be monitored; these parameters can be measured or calculated. Knowing at least some of these parameters allows for the calculation of density changes and volumetric foam flow rate changes as the foamed suspension is fed through a headbox and deposited onto the forming surface. According to this disclosure, all or some of the above parameters can also be determined on the discharge side of the forming surface. In this way, the discharge rate of fluid through the forming surface can be calculated and controlled based on the flow rate of the foamed suspension to the forming surface, in order to control and optimize the formation of a web with uniform properties. Specifically, monitoring parameters of the foam entering and exiting the forming surface can be used to prevent insufficient or excessive discharge of the web on the forming surface, so as to produce webs without fiber pad breakage, defects, or other irregularities that may be caused by unbalanced shear forces applied to the web.

[0075] See Figure 1 and Figure 2 This illustration shows one embodiment of a system and process according to the present disclosure. Generally, during this process, solid materials (such as fibers and / or superabsorbent particles), water, and a foaming agent are added to a tank and mixed until desired air content, bubble size / foam stability, and solid dispersion (such as fiber dispersion) are achieved. The fiber-containing foam can then optionally be diluted during the process, particularly in the presence of a recirculation flow. In one aspect, the air content of the foaming suspension is between about 30% and about 65%. As will be described below, the process and system of this disclosure specifically relate to online measurement of certain parameters of the foaming suspension to calculate the volumetric flow rate, air content, basis weight, and / or velocity of the foaming suspension at the forming surface. Below the moving forming surface is one or more discharge devices that can apply a vacuum to the web during web forming and draw excess foam across the forming surface for controlling sheet formation. Various parameters of the discharged foam are also measured within a discharge line located downstream of the forming surface to calculate the volumetric flow rate of the foam discharged from the surface. Then, the volumetric flow rate of the foam discharged from the forming surface is controlled and regulated based on the volumetric flow rate of the foamed suspension fed onto the forming surface, in order to carefully control the properties of the nonwoven web being formed. The process and system disclosed herein are well-suited not only for producing single-layer webs but also for producing multi-layer webs. In the production of multi-layer webs, shear forces can be controlled and / or minimized to improve interlayer boundaries.

[0076] Figure 1 Examples are illustrated for the production of foamed fiber suspensions and for forming webs from the foamed fiber suspensions. It should be understood that any suitable web forming system can be used according to this disclosure, and Figure 1 Provided for illustrative purposes only. Figure 1 As shown, the system may include a mixing tank 12 for forming a foamed fiber suspension. The foamed fiber suspension is then fed into a web forming system 10 or headbox, which deposits the foamed fiber suspension onto a porous forming surface 26 for forming a web 14. According to this disclosure, the web forming system or headbox 10 includes one or more adjacent forming zones combined with one or more corresponding discharge devices and discharge lines for controlling and coordinating the inflow of the aqueous fiber suspension and the discharge flow through the forming surface 26 to control web forming. Figure 2 The image shows a web forming system 10 in more detail.

[0077] In an alternative embodiment, the system for producing the web can be a double-web forming system. In the double-web forming machine, two webs each form a loop, and as the two webs travel with raw material sandwiched between them, fluid is removed by means of a discharge device, thus allowing the fiber mat to gradually grow and form the web. The double-web forming machine is characterized by, as Figure 1 As shown, faster operating speeds can be achieved by eliminating the free surface of the raw materials.

[0078] See Figure 3 The image shows a partial view of one embodiment of a dual-web forming system. One or more layers from independent forming zones of a foamed fiber suspension are ejected from a headbox 210 between two forming surfaces 226 and 228 to form a web 214. The two forming surfaces may be guided by a forming roller and a breast roller, respectively. The web 214 travels along an approximate curve on the sides of the forming surface 226 along a plurality of spaced-apart boot-shaped blades.

[0079] The foamed fiber suspension can be dehydrated at almost the same rate through the two forming surfaces 226 and 228. For example, as will be discussed below... Figure 2 In a more detailed description, the emission device having a controller for controlling the emission rate can be positioned adjacent to the forming surface 226 and adjacent to the forming surface 228.

[0080] Return to reference Figure 1 The mixing tank 12 is connected to a water supply 22 for feeding water into the tank and a foaming agent or surfactant supply 24 for feeding surfactants into the tank 12. Fiber feedstock is fed into the tank 12 and combined with water and surfactants. The aqueous solution formed by mixing surfactants and water can be agitated and foamed to form a foamed fiber suspension. As described above, various other materials besides fibers can be combined in the tank 12. For example, such other materials may include superabsorbent particles, etc.

[0081] The surfactant or blowing agent may contain any suitable surfactant. In one embodiment, for example, the blowing agent may contain sodium lauryl sulfate, also known as sodium lauryl polyoxyethylene ether sulfate or sodium lauryl ether sulfate. Other blowing agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other embodiments, the blowing agent may contain any suitable cationic and / or amphoteric surfactant. For example, other blowing agents include fatty acid amines, amides, amine oxides, fatty acid quaternary ammonium compounds, etc.

[0082] In one embodiment, a nonionic surfactant is used. For example, the nonionic surfactant may include alkyl polysaccharides. For example, in one aspect, the surfactant may be a C8 alkyl polysaccharide, a C10 alkyl polysaccharide, or a mixture of C8 alkyl polysaccharides and C10 alkyl polysaccharides.

[0083] The foaming agent is generally combined with water in an amount greater than about 0.1% by weight, such as greater than about 0.5% by weight, such as greater than about 0.7% by weight. One or more foaming agents are generally present in an amount from about 0.01% by weight to about 5% by weight, such as in an amount of up to about 2% by weight.

[0084] Once a foaming agent and water are combined, the mixture is blended or otherwise subjected to forces capable of forming foam. Foam typically refers to an aggregate of hollow cells or air bubbles.

[0085] Foam density can vary depending on the specific application and various factors, including the fiber formulation used. In one embodiment, for example, the foam density can be greater than about 200 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. Foam density is generally less than about 600 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 one embodiment, for example, a lower density foam with a foam density generally less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L is used. The foam will generally have an air content greater than about 40%, such as greater than about 50%, such as greater than about 60% (at standard temperature and pressure (STP)). The air content is generally less than about 75% by volume, such as less than about 70% by volume, such as less than about 65% by volume.

[0086] The foam can be formed in the presence of the fiber ingredients, or alternatively, the foam can be formed first and then combined with the fiber ingredients. Generally, any fiber capable of manufacturing a substrate (such as a thin paper web or other similar type of nonwoven fabric) according to this disclosure can be used.

[0087] Fibers suitable for preparing webs include any natural or synthetic cellulose fibers, including but not limited to non-wood fibers such as cotton, Manila hemp, kenaf, Indian grass, flax, thatch, straw, jute, bagasse, milkweed, and pineapple leaf fibers; and woody or pulp fibers, such as those obtained from broadleaf and coniferous trees, including softwood fibers such as northern and southern softwood kraft paper fibers; and hardwood fibers such as eucalyptus, maple, birch, and aspen. Pulp fibers can be prepared in high-yield or low-yield forms and can be pulped by any known method (including kraft paper, sulfite, high-yield pulping methods) and other known pulping methods. Fibers prepared by organic solvent pulping methods can also be used.

[0088] A portion of the fiber (such as up to 100% or less on a dry weight basis, or about 5% to about 30% on a dry weight basis) may be a synthetic fiber, such as rayon, polyolefin fiber, polyester fiber, bicomponent core-sheath fiber, multicomponent binder fiber, etc. The fiber may be virgin or recycled. The fiber may be a short fiber and may have an average length of about 3 mm to about 150 mm. An example polyethylene fiber is available from Minifibers, Inc. (Jackson City, Tenn.). When containing synthetic polymer fibers, the web can be thermally bonded at the fiber intersections.

[0089] Synthetic cellulose fiber types include all varieties of rayon and other fibers derived from viscose or chemically modified cellulose. Chemically treated natural cellulose fibers, such as mercerized pulp, chemically hardened or cross-linked fibers, or sulfonated fibers, can be used. To achieve good mechanical properties when using papermaking fibers, it may be desirable for the fibers to be relatively undamaged and largely unrefined or only slightly refined. While regenerated fibers can be used, virgin fibers are generally available due to their mechanical properties and lack of contaminants. Mercerized fibers, regenerated cellulose fibers, cellulose produced by microorganisms, rayon, and other cellulose materials or cellulose derivatives can be used. Suitable papermaking fibers may also include regenerated fibers, virgin fibers, or mixtures thereof. In some embodiments that enable high bulk and good compressibility, the fibers may have a Canadian standard freeness of at least 200, more specifically at least 300, more specifically at least 400, and most specifically at least 500.

[0090] Other papermaking fibers that can be used in this disclosure include secondary paper or recycled fibers and high-yield fibers. High-yield pulp fibers are those papermaking fibers produced by pulping processes that provide a yield of about 65% or more, more specifically about 75% or more, and even more specifically about 75% to about 95%. Yield is the amount of processed fiber obtained as a percentage of the initial wood mass. Such pulping processes include bleached chemothermal-mechanical pulp (BCTMP), chemothermal-mechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high-yield nitrite pulp, and high-yield kraft pulp, all of which result in fibers with high levels of lignin. High-yield fibers are known for their stiffness relative to typical chemically pulped fibers in both dry and wet states.

[0091] Web fabric can also be formed without significant internal fiber-to-fiber bond strength. In this regard, the fiber formulation used to form the base web fabric can be treated with a chemical detacker. The detacker can be added to the foamed fiber slurry during the pulping process or directly to the headbox. Suitable detackers that can be used in this disclosure include cationic detackers, such as aliphatic dialkyl quaternary ammonium salts, monoaliphatic alkyl tertiary ammonium salts, primary amine salts, imidazoline quaternary salts, organosilicon quaternary salts, and unsaturated aliphatic alkyl ammonium salts. Other suitable detackers are disclosed in U.S. Patent No. 5,529,665 to Kaun, which is incorporated herein by reference. Specifically, Kaun discloses the use of cationic organosilicon compositions as detackers.

[0092] In one embodiment, the detacking agent used in the process of this disclosure is an organic quaternary ammonium chloride, and more specifically, an organosilicon amine salt of quaternary ammonium chloride. For example, the detacking agent may be PROSOFT.RTM.TQ1003 sold by Hercules Corporation. The detacking agent may be added to the fiber slurry in an amount of about 1 kg / ton of fiber to about 10 kg / ton of fiber present in the slurry.

[0093] In an alternative embodiment, the detacker may be an imidazoline-based agent. Imidazolline-based detackers may be obtained, for example, from Witco Corporation. Imidazolline-based detackers may be added in amounts ranging from 2.0 to about 15 kg per metric ton.

[0094] Other optional chemical additives may also be added to the aqueous papermaking ingredients or the initial web formed to impart additional benefits to the product and process. The following materials are examples of other chemicals that can be applied to the web. These chemicals are examples and are not intended to limit the scope of the invention. Such chemicals can be added at any time during the papermaking process.

[0095] Other types of chemicals that can be added to the paper web include, but are not limited to, absorbent additives such as low molecular weight polyethylene glycol and polyhydroxy compounds such as glycerin and propylene glycol, which are typically in the form of cationic, anionic, or nonionic surfactants, humectants, and plasticizers. Materials that provide skin health benefits, such as mineral oil, aloe vera extract, vitamin E, silicones, and general emulsions, can also be incorporated into the finished product.

[0096] Generally, the products disclosed herein can be used in combination with any known materials and chemicals that are not opposed to their intended use. Examples of such materials include, but are not limited to, odor control agents such as odor absorbers, activated charcoal fibers and granules, baby powder, baking soda, chelating agents, zeolites, fragrances or other odor masking agents, cyclodextrin compounds, oxidants, etc. Superabsorbent granules may also be used. Additional options include cationic dyes, optical brighteners, humectants, emollients, etc.

[0097] Once the foamed fiber suspension is formed in tank 12, it can be fed into... Figure 2 The web forming system shown. For example... Figure 2 As illustrated, the web forming system 10 includes one or more forming zones. Figure 2 The illustrated embodiment shows three forming regions, including a first forming region 50, a second forming region 52, and a third forming region 54. Forming regions 50, 52, and 54 are positioned along the porous forming surface 26. In one embodiment, as... Figure 2 As shown, the porous forming surface 26 may be inclined relative to a horizontal plane. For example, the angle between the porous forming surface 26 and the horizontal plane may be greater than about 10°, such as greater than about 20°, such as greater than about 30°, and typically less than about 60°, such as less than about 50°. Each forming zone 50, 52, and 54 is designed to receive individual and independent flows of foamed fiber suspension for depositing the foamed fiber suspension onto the forming surface 26. For example, the first forming zone 50 may deposit the foamed fiber suspension directly onto the forming surface 26. However, the second forming zone 52 may be configured to deposit a second flow rate of foamed fiber suspension on top of the fibers deposited by the first forming zone 50. Similarly, the third forming zone 54 may deposit an aqueous suspension flow of fibers on top of the fibers deposited by the first forming zone 50 and the second forming zone 52. In this way, a multilayer web is formed. However, it should be understood that the systems and processes of this disclosure may include only a single forming zone for forming a single-layer web.

[0098] like Figure 2 As shown, each forming zone 50, 52, and 54 is in fluid communication with a separate and independent foam fiber supply line. For example, the first forming zone 50 is in fluid communication with a first foam fiber supply line 56, the second forming zone 52 is in fluid communication with a second foam fiber supply line 58, and the third forming zone 54 is in fluid communication with a third foam fiber supply line 60. The supply lines 56, 58, and 60 are configured to feed a foam fiber suspension into each of the corresponding forming zones 50, 52, and 54 with determined and selected flow characteristics, such as flow rate (e.g., volumetric flow rate), pressure, air content, and / or density. In this respect, each of the supply lines 56, 58, and 60 may be in fluid communication with a mixing tank 12, such as... Figure 1As shown. For example, the first supply line 56 may include a first injection line 62 connected to the mixing tank 12. Similarly, the second supply line 58 may include a second injection line 64, and the third supply line 60 may be in communication with the third injection line 66. Injection lines 62, 64, and 66 may all be in communication with the mixing tank 12 for feeding the foamed fiber suspension into each of the forming zones 50, 52, and 54. Alternatively, the system may include separate mixing tanks, wherein each injection line 62, 64, and 66 may be connected to a different mixing tank for feeding the foamed fiber suspension into the web forming system 10.

[0099] As shown in the figure, each of the foamed fiber supply lines 56, 58, and 60 may include a pumping device, a flow meter (such as a volumetric flow meter), a pressure monitoring device, and / or a temperature monitoring device. Each foamed fiber supply line 56, 58, and 60 may also be connected to a density monitoring device. For example, the density monitoring device may be part of other devices, such as a flow meter. Alternatively, information received from other instruments may be used to calculate the density of the foamed fiber suspension.

[0100] For example, a first foamed fiber supply line includes a first pumping device 68, a first flow meter 74, a first pressure monitoring device 80, and a first temperature monitoring device 81; a second foamed fiber supply line 58 includes a second pumping device 70, a second flow meter 76, a second pressure monitoring device 82, and a second temperature monitoring device 83; and a third foamed fiber supply line 60 includes a third pumping device 72, a third flow meter 78, a third pressure monitoring device 84, and a third temperature monitoring device 85. According to this disclosure, the pumping devices 68, 70, and 72 can be adjusted such that the foamed fiber suspension can be independently fed to each forming zone 50, 52, and 54 at a desired flow rate and / or pressure. The flow meters 74, 76, and 78, the pressure monitoring devices 80, 82, and 84 (such as volumetric flow rate), and the temperature monitoring devices 81, 83, and 85 can monitor the flow rate, pressure, and temperature upstream of the forming surface to calculate at least one characteristic of the flow of the foamed fiber suspension at the forming surface.

[0101] In one embodiment, flow meters 74, 76, and 78, pressure monitoring devices 80, 82, and 84, and temperature monitoring devices 81, 83, and 85 may be positioned in communication with one or more controllers. The controllers may include a microprocessor or any suitable programmable device. Pumping devices 68, 70, and 72 may also be positioned in communication with one or more controllers. The controllers may be configured to regulate pumping devices 68, 70, and 72 based on information received from flow meters 74, 76, and 78, pressure monitoring devices 80, 82, and 84, and / or temperature monitoring devices 81, 83, and 85. In this way, the foamed fiber suspension may be fed into each forming zone 50, 52, and 54 at a desired flow rate and / or pressure within a desired set point for optimizing the formation of the web on the forming surface 26.

[0102] Information received from flow meters 74, 76, and 78, from pressure monitoring devices 80, 82, and 84, and / or from temperature monitoring devices 81, 83, and 85 can be used to determine the characteristics of the foamed fiber suspension at the measurement location. Additionally, the density of the foamed fiber suspension can be measured or calculated based on information received from various instruments. In one embodiment, this information can be transmitted to a controller for calculating at least one characteristic of the foamed fiber suspension at the forming surface. Specifically, the controller can be programmed to correct for a determined volumetric flow rate at the forming surface based on changes in density, pressure, and temperature. For example, when the foamed suspension is ejected from a supply line onto the forming surface, the foamed suspension may experience a pressure drop that changes the density of the foamed suspension. For example, a method for calculating downstream values ​​of a foamed suspension is disclosed in U.S. Patent 4,764,253, which is incorporated herein by reference.

[0103] As described above, in one embodiment, the density of the foamed suspension is directly determined or calculated. In one aspect, a density monitoring device (e.g., a densitometer) can be integrated with... Figure 2 In the illustrated system, for example, the density monitoring device can be part of flow meters 74, 76, and 78. The density monitoring device can directly measure density. Alternatively, density can be measured in other ways. For example, the air content of the foamed suspension can be determined first, and the density can be calculated based on the measured pressure.

[0104] In one aspect, the measured characteristics of the foamed suspension within supply lines 56, 58, and 60 can be combined with other known information to calculate one or more characteristics of the foamed suspension at the forming surface. For example, in one embodiment, in addition to measuring or determining the flow rate (mass flow rate and / or volumetric flow rate), density, temperature, and pressure of the foamed suspension, other information may be fed to the controller, including the amount or concentration of solid material contained in the feedstock, the width of the forming surface, the velocity of the forming surface, and the desired basis weight of the layer, to calculate and / or determine at least one setpoint, such as the volumetric flow rate of the foamed suspension fed to the forming surface.

[0105] Foamed suspensions are two-phase fluids. They consist of a liquid volume fraction and a gas volume fraction. The gas volume fraction is also known as the volumetric air content. The volumetric air content can be determined by dividing the weight of one liter of foam by the weight of one liter of water (e.g., 1,000 g). The volumetric air content of a foamed suspension depends on pressure. In other words, the volumetric air content and density of a foamed suspension change with pressure.

[0106] In one aspect, when performing calculations, the solid component of the foam can be neglected and assumed to be part of the liquid phase. The flow rate (L / min) of the foamed suspension can be expressed as the sum of the liquid flow rate (L / min) and the gas phase flow rate (L / min). The liquid volume fraction of the foam is the volume percentage of all liquid foam and can be determined by dividing the liquid flow rate (L / min) by the foam flow rate (L / min). The liquid volume fraction can also be calculated based on the measured or calculated density of the foamed suspension. The total foam flow rate (L / min) can then be calculated by dividing the feed flow rate (L / min) by the liquid volume fraction. The gas flow rate of the foamed suspension can be determined by subtracting the liquid flow rate (L / min) from the foamed suspension flow rate (L / min). All of the above determinations are based on... Figure 2 The measurement location is in the middle.

[0107] To calculate density and volumetric foam velocity variations at other points in the system (such as at the forming surface), pressure differences due to gas phase expansion or compression must be considered. Assuming constant temperature, the ideal gas law can be used to determine density and volumetric foam velocity variations. Alternatively, temperature variations within the system can be measured, calculated, or estimated, thus taking into account in the ideal gas law. In this way, Figure 2 One or more properties of the foamed suspension, including density and volumetric flow rate, are determined at the locations of the illustrated flow meters 74, 76, and 78, and then calculated at the forming surface.

[0108] In addition to the measurements and calculations described above, the basis weight of the web or layer formed on the forming surface can also be calculated. The basis weight calculation can be determined based on the area formed each time and the weight of solid material (such as fibers) delivered to the forming surface each time (e.g., fiber flow rate). The area of ​​the web formed per unit time can be determined based on the width and velocity of the forming surface. The desired solid or fiber flow rate can be calculated by multiplying the target basis weight by the area formed each time. To determine the actual solid or fiber mass flow rate, it can be assumed that the weight of water is the total mass of the fluid moving through the system. The density difference between fibers and water, and the effect of temperature on the density of water, are negligible. Therefore, the mass flow rate can be calculated by dividing the mass flow rate of the fibers fed into the system by the amount of fibers contained in the liquid phase of the foamed suspension. Alternatively, the mass flow rate of the fibers can also be measured directly.

[0109] In one aspect, the controller can be programmed to have at least one predetermined or pre-selected reference value for a characteristic of the foamed suspension. For example, the controller can be programmed to have a desired volumetric flow rate value and / or mass flow rate value. These values ​​can be calculated by the controller and compared with preset values. Based on the comparison between the preset values ​​and the calculated or measured values, the controller can be configured to control the pumping devices 68, 70, and 72 in response to any deviation from the preset values. In this way, the controller can control the volumetric flow rate of the foamed suspension to the forming surface and / or the basis weight of the layer being formed.

[0110] In addition to controlling the flow characteristics of the foamed suspension fed onto the molding surface, the systems and processes disclosed herein also include similar components for measuring and / or determining similar characteristics of the discharged fluid exiting through the molding surface. For example, the fluid exiting the molding surface may also be in foam form, having both liquid and gas phases. Figure 2 As shown, the flow rate, temperature, pressure, and / or density of the discharged fluid can also be measured, determined, and / or calculated. Flow control devices can be placed on each discharge line to control the amount of fluid discharged from the forming surface based on the flow characteristics of the foamed suspension fed to the forming surface. In this way, the web formation can be controlled to optimize the properties of the web.

[0111] exist Figure 2 In the illustrated embodiment, various characteristics of the discharged fluid are measured and / or calculated downstream of the forming surface. These measurements are performed downstream of the forming surface and then used to calculate the flow velocity at the forming surface, taking into account changes in pressure, density, and / or temperature.

[0112] For example, such as Figure 2 As shown, opposite each forming zone 50, 52, and 54 is a corresponding discharge device that is in fluid communication with the corresponding discharge pipeline. Figure 2In the illustrated embodiment, each forming zone is aligned with a single discharge device, and an embodiment is provided to illustrate the process. On the other hand, in Figures 4 to 7 The image shows other systems and processes in which multiple emission devices are aligned with at least one forming zone. (See also: From...) Figures 4 to 7 It will be obvious that various advantages and benefits can be obtained when more than one emission device is aligned with at least one forming zone within the system.

[0113] As used herein, the discharge device is "aligned" with the forming region when the length of the discharge device relative to the forming region is positioned such that the discharge device does not extend beyond the length of the forming region by more than about 20%. For example, for illustrative and explanatory purposes, one embodiment of the forming region 300 is shown. As shown, the forming region 300 includes a first layer of material foam suspension 302 deposited near an inclined porous forming surface 26. The first material foam suspension 302 can be discharged from a first headbox.

[0114] like Figure 8 As shown, the second material foaming suspension is also fed into the process from the second headbox. Figure 8 The illustrated embodiments show two different flow flows. However, the system and process may contain only a single flow flow, or may include more than two flow flows.

[0115] A first flow of the foamed material suspension 302 is fed into the forming zone 300 by being deposited onto the moving porous forming surface 26. The first flow of the foamed material suspension 302 is separated from a second flow of the foamed material suspension 304 by a baffle or sheet 306. As used herein, the length of the forming zone is the distance between the location where the foamed material suspension is deposited on the moving porous forming surface 308 and the location where the baffle or sheet 306 terminates. Figure 8 As shown, the forming area 300 has a length L.

[0116] According to this disclosure, the emission device is aligned with the forming region as long as it does not extend beyond the length L of the forming region by more than 20%. In other embodiments, one or more emission devices may be entirely positioned within the length of the forming region. Alternatively, one or more emission devices may extend beyond the length of the forming region by less than about 15%, such as less than about 10%, such as less than about 5%, such as less than about 2%.

[0117] See back Figure 2 Along the forming surface 26, opposite to the first forming area 50, is a first discharge device 86 in fluid communication with the first discharge line 92. Opposite to the second forming area 52 is a second discharge device 88 in fluid communication with the second discharge line 94. Similarly, opposite to the third forming area 54 is a third discharge device 90 communicating with the third discharge line 96. Figure 2 As shown, forming zones 50, 52, and 54 are adjacent to each other along forming surface 26 and positioned on one side of the forming surface. Discharge devices 86, 88, and 90 are also adjacent to each other and positioned on the side of forming surface 26 opposite to forming zones 50, 52, and 54. As the foamed fiber suspension is deposited from each forming zone 50, 52, and 54 onto the forming surface, web 14 is formed, and excess fluid enters the corresponding discharge devices 86, 88, and 90. The discharge device can be any suitable static or dynamic discharge device capable of discharging fluid from the web or from the forming surface. The discharge device can be a static suction box or a static vacuum box. Alternatively, the discharge device can be a roller, such as a rotating roller that applies suction.

[0118] like Figure 2 As shown, each discharge line 92, 94, and 96 includes a corresponding flow control device, flow meter, temperature monitoring device, and pressure monitoring device. For example, the first discharge line 92 includes a first flow control device 98, a first flow meter 104, a first temperature monitoring device 105, and a first pressure monitoring device 110. The second discharge line 94 includes a second flow control device 100, a second flow meter 106, a second temperature monitoring device 107, and a second pressure monitoring device 112. The third discharge line 96 includes a third flow control device 102, a third flow meter 108, a third temperature monitoring device 109, and a third pressure monitoring device 114. Optional flow control devices 98, 100, and 102 can be any suitable device for controlling the flow through the line and can be an adjustable valve or a pump. For example, a pump can be used to apply suction to a shaped surface. Alternatively, discharge can occur by gravity. In yet another embodiment, each flow control device 98, 100, and 102 can be a combination of a pump and an adjustable valve.

[0119] In one embodiment of this disclosure, each discharge line 92, 94, and 96 is controlled independently of the other discharge lines. The flow rate or discharge volume from each discharge device 86, 88, and 90 through each corresponding discharge line 92, 94, and 96 can be regulated and controlled based on at least one characteristic of the foamed fiber suspension fed into each of the forming zones 50, 52, and 54, as described above. For example, in one embodiment, the flow rate or discharge volume from each discharge device can be based on the volumetric flow rate of the foamed fiber suspension fed into each forming zone. For example, flow meters 104, 106, and 108, combined with pressure monitoring devices 110, 112, and 114, temperature monitoring devices 105, 107, and 109, and / or optionally one or more density monitoring devices, can be used to quantify the discharged fluid, which may be a two-phase discharge stream comprising liquid and gas. The two-phase discharge flow can be converted into a reference pressure based on information received from flow meters 104, 106, and 108, pressure monitoring devices 110, 112, and 114, temperature monitoring devices 105, 107, and 109, and / or density monitoring devices. Different techniques and methods can be used to control the flow rate (mass or volume) of the fluid through each discharge device. For example, flow control devices 98, 100, and 102 can be adjusted and controlled to achieve an optimal or desired discharge flow rate based on at least one characteristic of the foamed fiber suspension fed into each of the forming zones 50, 52, and 54. In one aspect, for example, the flow control device may include a suction device that applies suction to the forming surface to discharge fluid. The flow rate of the fluid discharged through each discharge device can be controlled by adjusting the suction applied to the forming surface. In another aspect, the suction applied to the forming surface may be constant, and a downstream valve or other device may be used to control the discharge. In yet another embodiment, the fluid may be discharged by gravity, and a valve or similar device may be used to control the flow rate.

[0120] In one aspect, for example, the characteristics of the two-phase discharge fluid flowing through discharge lines 92, 94, and 96 can be measured or calculated downstream of the forming surface. Then, one or more characteristics of the foam discharged from the forming surface can be determined based on the measured and calculated characteristics of the foam downstream of the forming surface using the same calculations described above.

[0121] In one embodiment, the system may further include one or more controllers 116. The controller may be a microprocessor or any suitable programmable device. Figure 2As shown, each flow control device 98, 100, and 102, each flow meter 104, 106, and 108, each temperature monitoring device 105, 107, and 109, each density monitoring device, and / or each pressure monitoring device 110, 112, and 114 can communicate with the controller 116. The controller can receive information from the flow meters 104, 106, and 108, the temperature monitoring devices 105, 107, and 109, the optional density monitoring devices, and / or the pressure monitoring devices 110, 112, and 114 for regulating the flow control devices 98, 100, and 102 to control the flow rate of fluid discharged from each of the discharge devices 86, 88, and 90. A combination of information received from flow control devices 98, 100, and 102 (which may be volumetric flow meters), pressure monitoring devices 110, 112, and 114, temperature monitoring devices 105, 107, and 109, and / or optional density monitoring devices can be used to quantify the fluid discharge flow containing both gas and liquid. In one embodiment, controller 116 can use the aforementioned information to calculate the flow rate (e.g., volumetric flow rate) at the forming surface and control the volumetric flow rate based on at least one characteristic of the foamed suspension fed to the forming surface. Controller 116 can then control flow control devices 98, 100, and 102 to achieve the calculated discharge flow rate through each discharge device and discharge line.

[0122] In one aspect, controller 116 can determine the volumetric flow rate of the foam discharged from the forming surface and can adjust the volumetric flow rate based on the volumetric flow rate of the foamed suspension fed to the forming surface. Alternatively, the discharge system can apply a vacuum to the forming surface at each discharge device in the discharge apparatus. In this embodiment, controller 116 can determine a reference pressure based on information received from all measuring devices and instruments located downstream. Controller 116 can then adjust the reference pressure at the forming surface based on the characteristics of the foamed suspension, such as the volumetric flow rate of the foamed suspension.

[0123] The process disclosed herein allows for precise control of foam discharge from the forming surface for web production, based on the amount of foam and fiber fed to the forming surface, without over- or under-discharge of the web during forming. In this way, webs with uniform properties and reinforcing characteristics can be produced.

[0124] exist Figure 2 In the illustrated embodiments, flow control devices 98, 100, and 102 are shown as valves. In other embodiments, however, flow control devices 98, 100, and 102 may be pumping devices for pumping fluid through a discharge line at a desired flow rate. In one aspect, each flow control device may be a combination of a pumping device and a valve.

[0125] According to this disclosure, the discharge flow rate through each discharge line 92, 94, and 96 can be coordinated with the flow rate and / or pressure of the foamed fiber suspension fed into each of the forming zones 50, 52, and 54. By controlling the discharge flow rate based on the supply flow rate, the formation of the web can be controlled to optimize properties. When producing multilayer webs, such as... Figure 2 As shown, the discharge flow rate can be controlled relative to the input pressure and / or flow rate to further enhance interlayer mixing, thereby further improving the physical properties of the web during web formation.

[0126] For example, such as Figure 2 As shown, by controlling the discharge flow rate relative to the input flow rate, the foamed fiber suspension fed into each forming zone 50, 52, and 54 can be spread onto the forming surface 26 in a unique manner. For example, as indicated by the arrows, the foamed fiber suspension fed into each forming zone 50, 52, and 54 can be allowed to flow laterally beyond the periphery of each forming zone to induce fiber reorientation and / or layer mixing. For example, in one embodiment, the discharge flow rate at discharge devices 86, 88, and 90 can be maintained at a lower flow rate than that of the foamed fiber suspension fed into each of the forming zones 50, 52, and 54. The pressure differential generated at the intersection of forming zones 50, 52, and 54 with the forming surface 26 can produce fiber mixing and reorientation as well as longitudinal flow, such as... Figure 2 As shown.

[0127] In one embodiment, the process and system of this disclosure may further include a sealing region 120 positioned along the shaped fabric 26 and in fluid communication with a sealing fluid supply line 122. Figure 2 As shown, the sealing fluid supply line 122 may include a pumping device 124, a flow meter 126, a pressure monitoring device 128, and a temperature monitoring device 129. The sealing fluid supply line 122 is used to feed fluid, particularly a liquid, into the sealing zone 120. The sealing fluid can be any suitable liquid. For example, the sealing fluid can be water, water, and surfactant solutions, etc. In one embodiment, the sealing fluid is non-fibrous. The sealing fluid is fed into the sealing fluid zone 120 at a certain flow rate and / or pressure, such that the sealing fluid deposited on the forming surface 26 forms a fluid seal that prevents airflow in the upstream longitudinal direction. Information received from the flow meter 126, the pressure monitoring device 128, the temperature monitoring device 129, and the optional density monitoring device can be used to calculate the volumetric flow rate of the foam at the forming surface.

[0128] like Figure 2As shown, the sealing region 120 can be positioned upstream of and adjacent to a plurality of forming regions. The sealing region 120 can also be positioned opposite a sealing discharge device 130 connected to a sealing discharge line 132. The sealing discharge line 132 may include a flow control device 134, a flow meter 136, a temperature monitoring device 137, and a pressure sensing device 138, all of which can communicate with the controller 116. In this way, the discharge rate of the sealing fluid can be carefully controlled based on the flow rate or pressure of the sealing fluid entering or leaving the sealing region 120. By including the sealing region 120, the web 14 is better formed opposite the first forming region 50.

[0129] like Figure 2 The illustrated web forming system 10 may further include a suction zone 140 adjacent to and positioned downstream of a plurality of forming zones. The suction zone 140 is in fluid communication with a discharge line 142, which may include a pressure monitoring device 144. The suction zone 140 is used to suction fluid from the initial web 14 after web forming. The suction zone 140 is used to remove excess fluid, particularly liquids, from the web 14. In one aspect, the discharge flow rate of the foamed fiber suspension discharged through one or more discharge devices is controlled such that excess fluid from one or more forming zones enters the suction zone 140. Ideally, the suction zone 140 facilitates the removal of fluid from the web 14 without causing any harmful effects.

[0130] In one embodiment, one or more discharge devices 86, 88 and 90 are operated such that the foamed fiber suspension fed into forming zones 50, 52 and 54, and particularly the third forming zone 54, causes excess liquid to flow longitudinally beyond the periphery of the third forming zone 54 for collection at the suction zone 140.

[0131] In one implementation scheme, such as Figure 2 As shown, all discharge lines 92, 94, 96, 132, and 142 can be fed into separator 150. Separator 150 can be configured to separate free gas from foam. As shown, separator 150 may include a gas outlet 152 and a liquid outlet 154 that can be connected to a vacuum source. The liquid collected in separator 150 may include a mixture of water and surfactants. Figure 2 As shown, pumping device 156 can be used to pump liquid from separator 150 to liquid tank 158, which can also be connected to water source 160. Liquid tank 158 can be used to recycle the water and surfactant mixture back into the process via supply lines 56, 58, 60 and 122.

[0132] Figure 2The illustrated web forming system offers various advantages and benefits in forming webs from a foamed fiber suspension. For example, by controlling the flow through the discharge line relative to the flow of the foamed fiber suspension into the forming zone, the detrimental effects of suction on the foam material during web forming can be minimized. Furthermore, the alignment of the input pressure and discharge flow across multiple forming zones enables stable sheet formation and allows for the production of multilayer webs with controlled and / or optimized mixing between different layers of the web.

[0133] See Figure 1 After the initial web 14 is formed from the web forming system or headbox 10, the web can be fed into various downstream processes. Figure 1 This illustration only shows one embodiment of the process for drying the web after formation. As shown, the web 14 is formed on the forming surface 26 and conveyed downstream. For example, the annularly traveling formed fabric 26 may be supported and driven by rollers 28.

[0134] Once formed on the shaped fabric 26, the shaped web can have a consistency of less than about 50%, such as less than about 20%, such as less than about 10%, such as less than about 5%. In practice, the forming consistency can be less than about 2%, such as less than about 1.8%, such as less than about 1.5%. The forming consistency is typically greater than about 0.5%, such as greater than about 0.8%.

[0135] Once a wet web is formed on the shaped fabric 26, the web is conveyed downstream and optionally further dehydrated. For example, the process may optionally include multiple vacuum devices 16, such as vacuum chambers and vacuum rollers. Vacuum chambers help remove moisture from the newly formed web 14.

[0136] like Figure 1 As shown, the formed fabric 26 can also be positioned in communication with a steam box 18 positioned above a pair of vacuum rollers 20. The steam box 18 can, for example, significantly increase dryness and reduce transverse moisture variation. Steam applied from the steam box 18 heats the moisture in the wet web 14, making it easier for water to drain from the web, especially when combined with the vacuum rollers 20. The newly formed web 14 is conveyed downstream from the formed fabric 26 and dried. Any suitable drying apparatus can be used to dry the web. For example, the web can be air-dried or placed on heated drying rollers and wrinkled or unwrinkled. For example, in Figure 1 In this process, the web 14 is formed to contact two heated drying rollers 38 and 40. In one embodiment, the web can be fed from the drying rollers 38 and 40 into a ventilated dryer before being wound into a roll.

[0137] As described above, in one aspect, at least one forming zone in the system can be positioned to align with multiple discharge devices. Using multiple discharge devices allows for better control of the amount of fluid or moisture discharged from the web. Positioning multiple discharge devices to align with a single forming zone can also be used to control fiber properties. For example, the discharge devices can be used to induce fiber mixing and / or control fiber alignment.

[0138] See Figure 4 For example, one embodiment of a web forming system manufactured according to this disclosure is shown, wherein the system includes a single forming zone positioned in alignment with three dispensing devices. Similar reference numerals are used to indicate similar elements.

[0139] As shown, the system includes an injection line 62 for injecting a foamed fiber suspension into a system adjacent to a pump 68. Pump 68 delivers the foamed fiber suspension to a forming zone 50. A flow meter 74, a pressure monitoring device 80, and a temperature monitoring device 81 monitor the flow rate, pressure, and temperature upstream of the forming surface to calculate at least one characteristic of the flow of the foamed fiber suspension at the forming surface.

[0140] Positioned opposite the forming zone 50 are three discharge devices 86A, 86B, and 86C aligned with the forming zone. Each discharge device 86A, 86B, and 86C is connected to a corresponding discharge line 92A, 92B, and 92C. Each discharge line 92A, 92B, and 92C includes corresponding flow control devices 98A, 98B, and 98C, flow meters 104A, 104B, and 104C, temperature monitoring devices 105A, 105B, and 105C, and pressure monitoring devices 110A, 110B, and 110C. All instruments can communicate with a controller 116, which may include one or more microprocessors.

[0141] exist Figure 4 In the illustrated embodiments, each emission device 86A, 86B, and 86C can operate independently of the other emission devices. Therefore, when the foamed fiber suspension is deposited on the forming surface, the amount of emission occurring along the forming surface within the forming zone 50 can be controlled, regulated, and modified based on any desired outcome.

[0142] In one implementation, for example, a larger amount of discharge can occur through discharge device 86A compared to discharge devices 86B and 86C, in order to remove as much fluid as possible initially.

[0143] Alternatively, less emission may occur between emission devices 86A and 86B, while a larger emission may occur at emission device 86C. In this embodiment, a beneficial amount of fiber mixing may occur to produce a web having one or more desired properties.

[0144] In yet another embodiment, emissions generated through emission device 86B may be greater than emissions generated through emission devices 86A and 86C. For example, emission device 86B may be used for primary emissions, while other emission devices 86A and 86C may be used for supplementary emissions.

[0145] On the other hand, the systems and processes of this disclosure can be configured such that the discharge or flow rate of fluid through each discharge device can be substantially the same. For example, the amount of suction applied to the shaped fabric can be varied relative to each discharge device to produce substantially the same flow rate through each discharge device. Figure 4 As shown, for example, the amount of fluid contained in the web being formed opposite to discharge device 86A will typically be greater than the amount of fluid contained in the web opposite to discharge devices 86B and 86C. To maintain relatively similar flow rates, discharge device 86A may apply a smaller suction force relative to discharge devices 86B and 86C to produce substantially the same discharge flow rate. In one embodiment, maintaining substantially the same discharge flow rate can provide various benefits and advantages, including better web formation and / or more uniform web formation.

[0146] For example, in one embodiment, the discharge flow rate between each discharge device 86A, 86B, and 86C may vary by no more than about 20%, such as no more than about 15%, such as no more than about 10%, such as no more than about 5%, such as no more than about 3%. In one specific embodiment, the flow rate of each discharge device relative to a single forming zone may vary by no more than 1%. In this way, the discharge flow rate profile may be constant or substantially constant over the length of a single forming zone.

[0147] Having more than one discharge device positioned aligned with the forming zone 50 provides excellent control over fluid discharge for creating a discharge profile along the length of the forming zone 50 that produces the desired result. Figure 4 In the illustrated embodiment, the forming zone 50 is aligned with three discharge devices 86A, 86B, and 86C. In other embodiments, however, the system may include only two, four, five, six, or even seven discharge devices aligned with the forming zone 50.

[0148] Figure 4 The illustrated processes and systems are typically used to form single-layer webs. See also Figures 5 to 7 This illustrates other embodiments of the system according to the present disclosure, which are designed to form multi-layered webs. Figures 5 to 7 In each of the illustrated systems, at least one forming zone is positioned in alignment with two discharge devices for controlling the discharge of fluid through the web during web formation.

[0149] exist Figures 5 to 7 In this context, similar reference numerals are used to indicate similar elements. For example... Figures 5 to 7 As shown, each system includes injection lines 62, 64, and 66 for injecting the foamed fiber suspension into the process of adjacent corresponding pumps or pumping devices 68, 70, and 72. Pumping devices 68, 70, and 72 feed the foamed fiber suspension into corresponding forming zones 50, 52, and 54.

[0150] Each pumping device 68, 70, and 72 is connected to a corresponding foamed fiber supply line 56, 58, and 60. Each foamed fiber supply line 56, 58, and 60 is connected to flow meters 74, 76, and 78, pressure monitoring devices 80, 82, and 84, temperature monitoring devices 81, 83, and 85, and an optional density monitoring device (not shown). The three foamed fiber supply lines 56, 58, and 60 are fed into corresponding forming zones 50, 52, and 54 for forming a three-layer web. In one embodiment, for example, the intermediate layer may include a superabsorbent material sandwiched between the two outer layers.

[0151] exist Figure 5 In the illustrated embodiment, the first forming zone 50 is aligned with two discharge devices 86A and 86B. Similarly, the second forming zone 52 is aligned with two discharge devices 88A and 88B. On the other hand, the third forming zone 54 is aligned with a single discharge device 90. As shown, discharge devices 86A and 86B are in fluid communication with corresponding discharge lines 92A and 92B. Each discharge line is connected to flow control devices 98A and 98B, flow meters 104A and 104B, temperature monitoring devices 105A and 105B, and pressure monitoring devices 110A and 110B.

[0152] Discharge devices 88A and 88B are connected to corresponding discharge lines 94A and 94B, respectively. Discharge lines 94A and 94B are connected to corresponding flow control devices 100A and 100B, flow meters 106A and 106B, temperature monitoring devices 107A and 107B, and pressure monitoring devices 112A and 112B.

[0153] Similar to Figure 2 The discharge device 90, aligned with the forming zone 54, is connected to the discharge pipeline 96, which includes a flow control device 102, a flow meter 108, a temperature monitoring device 109, and a pressure monitoring device 114.

[0154] exist Figure 5 In the illustrated embodiment, a larger number of discharge devices are positioned at the upstream end of the forming surface. Therefore, the discharge devices are more concentrated near the location where the web is first formed. In this way, fluid can be discharged from the web more efficiently after the first and second layers have been deposited onto the forming surface.

[0155] Alternatively, discharge devices 86A, 86B, 88A, and 88B can be used to promote fiber mixing. For example, 86B and 86A can be operated to discharge less fluid from the web compared to discharge devices 86A and 88B. In this way, interlayer mixing can occur between the first and second layers. Using multiple discharge devices allows interlayer mixing to occur without causing the fibers to mix to the point where the layers are no longer distinguishable.

[0156] See Figure 6 This illustrates another embodiment of the web forming system according to the present disclosure. Figure 6 and Figure 5 Similar to the previous configuration, the difference lies in that the third forming zone 54 is positioned to align with the two discharge devices 90A and 90B. Discharge devices 90A and 90B are connected to corresponding discharge lines 96A and 96B. Each discharge line 96A and 96B includes corresponding flow control devices 102A and 102B, flow meters 108A and 108B, temperature monitoring devices 109A and 109B, and pressure monitoring devices 114A and 114B.

[0157] Figure 6 Provided with Figure 5 Similar fluid discharge control, but with the difference that it provides stronger control on the opposite side of the third forming zone 54. For example, the system can be controlled to promote fiber mixing between the second and third layers of the web by including two discharge devices 90A and 90B opposite to the forming zone 54. For example, less discharge occurs through discharge devices 88A and 88B compared to discharge occurring at discharge devices 86B and 90A, to facilitate some fiber mixing between adjacent layers.

[0158] In yet another embodiment, all discharge devices 86A, 86B, 88A, 88B, 90A and 90B can be used to remove as much fluid and moisture as possible before downstream treatment.

[0159] See Figure 7 This illustrates yet another embodiment of the process and system according to the present disclosure. In this embodiment, a first forming region 50 is aligned with a first discharge box 86, which is in fluid communication with a discharge line 92. Similarly, a second forming region 52 is in communication with a single discharge device 88, which is in fluid communication with a discharge line 94.

[0160] On the other hand, the third forming zone is aligned with two discharge devices 90A and 90B. Discharge devices 90A and 90B are in fluid communication with corresponding discharge lines 96A and 96B. Positioned along discharge lines 96A and 96B are flow control devices 102A and 102B, flow meters 108A and 108B, temperature monitoring devices 109A and 109B, and pressure monitoring devices 114A and 114B. A controller 116, which may include one or more microprocessors, can be used to control the various components to increase or decrease the flow rate of fluid discharged through each discharge device 86, 88, 90A, and 90B and entering the corresponding discharge lines 92, 94, 96A, and 96B.

[0161] Aligning the multiple discharge devices 90A and 90B with the third forming zone 54 offers various advantages and benefits. For example, in one embodiment, reduced discharge through the discharge devices 88, 90A, and / or 90B can promote fiber blending between the second and third layers. For instance, if the second layer contains superabsorbent material, some of the superabsorbent material may be present in the third layer, rather than on the surface of the finished web. In this way, fluids in contact with the web during use can get closer to the superabsorbent particles without leaving the particles on the surface of the product and causing lint or otherwise greater friction on the outer surface.

[0162] Alternatively, discharge devices 90A and 90B can be used to increase fluid discharge at the ends of the forming surface during the formation of the third layer. Increasing discharge at the ends reduces the energy required to dry the web.

[0163] The webs manufactured according to this disclosure can be used in all different types of products. For example, tissue webs can be used to produce toilet paper, facial tissues, paper towels, industrial wipes, etc. In one embodiment, the webs manufactured according to this disclosure may contain a large amount of superabsorbent particles. For example, at least one layer of the web may contain more than about 50% by weight to up to about 90% by weight of superabsorbent particles, including all increments of 1% by weight therein. These types of webs are particularly suitable for incorporation into personal care absorbent articles. For example, the web can be used as an absorbent core positioned between a liquid-permeable liner and a liquid-impermeable outer cover.

[0164] 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 method for producing webs, comprising: The foamed suspension of the material is flowed to at least one forming zone, the foamed suspension being fed into the first forming zone at a first flow rate; The foamed suspension of the material fed into the first forming zone is deposited near at least one moving porous forming surface to form an initial web layer; Excess fluid is discharged through the porous forming surface to a first discharge device and a second discharge device, the first discharge device and the second discharge device being positioned aligned with the first forming area along the at least one porous forming surface; as well as The flow rate of the discharge fluid discharged through the first discharge device and the flow rate of the discharge fluid discharged through the second discharge device are controlled, wherein the flow rate of the discharge fluid discharged through the first discharge device is controlled independently of the flow rate of the discharge fluid discharged through the second discharge device.

2. The method of claim 1, wherein the flow rate of the discharge fluid discharged through the first discharge device and the flow rate of the discharge fluid discharged through the second discharge device are controlled based on at least one characteristic of the flow of the foamed suspension of the material fed into the first forming zone, wherein the at least one characteristic of the flow of the foamed suspension of the material includes the temperature, pressure, mass flow rate, volumetric flow rate, or density of the foamed suspension of the material.

3. The method of claim 1 or 2, wherein at least one of the layers of the initial web is a unique layer formed at the corresponding forming area.

4. The method of any of the preceding claims, wherein the first discharge device is positioned upstream of and adjacent to the second discharge device, and wherein the flow rate of the discharge fluid discharged through the first discharge device is greater than the flow rate of the discharge fluid discharged through the second discharge device.

5. The method of any one of claims 1 to 3, wherein the first discharge device is positioned upstream of and adjacent to the second discharge device, and wherein the flow rate of the discharge fluid discharged through the first discharge device is less than the flow rate of the discharge fluid discharged through the second discharge device.

6. The method of any one of claims 1 to 3, wherein the flow rate of the discharge fluid discharged through the first discharge device and the flow rate of the discharge fluid discharged through the second discharge device are substantially the same, such that the difference between the flow rate of the discharge fluid discharged through the first discharge device and the flow rate of the discharge fluid discharged through the second discharge device does not exceed about 20%, such as not exceeding about 15%, such as not exceeding about 10%, such as not exceeding about 5%, such as not exceeding about 3%.

7. The method of any of the preceding claims further includes the step of flowing the foamed suspension of the material to a second forming region located adjacent to the first forming region, wherein the foamed suspension of the material is fed into the second forming region at a second flow rate; The foamed suspension of material to be fed into the second forming zone is deposited near the at least one movable porous forming surface, such that a second layer of material is formed below or above the material deposited from the first forming zone near the forming surface to form a multilayer web; and The flow rate of the discharged fluid through a third discharge device is controlled, the third discharge device being positioned to align with the second forming zone.

8. The method of claim 7, wherein the second forming region is positioned downstream of the first forming region, and wherein the first discharge device and the second discharge device are positioned upstream of the formation of the second layer.

9. The method of claim 7, wherein the second forming region is positioned upstream of the first forming region, and wherein the first discharge device and the second discharge device are positioned downstream of forming the second layer.

10. The method of any one of claims 7 to 9, further comprising the step of flowing the foamed suspension of the material to a third forming zone located in a forming zone adjacent to other forming zones, wherein the foamed suspension of the material is fed into the third forming zone at a third flow rate; The foamed suspension of the material to be fed into the third forming zone is deposited near the at least one moving porous forming surface, such that a third layer of material is formed in the multilayer web; and The flow rate of the discharged fluid discharged through the fourth discharge device is controlled, the fourth discharge device being positioned to align with the third forming zone.

11. The method of any one of claims 1 to 6, wherein the method comprises only the first forming zone for producing a single-layer web.

12. The method of any of the preceding claims, wherein the sealing area is positioned adjacent to and upstream of all forming areas to suppress airflow in the upstream longitudinal direction.

13. The method of claim 12, wherein the sealing region, positioned adjacent to all forming regions and upstream of all forming regions, emits fluid relative to the at least one porous forming surface to suppress airflow.

14. The method of any of the preceding claims, wherein the first forming region has a length, and wherein at least one of the first discharge device or the second discharge device extends beyond the length of the first forming region.

15. The method of any one of claims 7 to 10, wherein the foamed suspension of the material is individually pumped to each forming zone, such that the fluid pressure upstream of each forming zone can be controlled independently of the other forming zones.

16. The method of any of the preceding claims, wherein the foamed suspension of the material is pumped to the first forming zone, and wherein prior to the first forming zone, the temperature, pressure, flow rate, and density of the foamed suspension of the material are determined to calculate the flow rate at the forming surface, and the flow rate of the discharged fluid discharged through the first and second discharge devices is controlled based on the calculated flow rate.

17. The method of any of the preceding claims, wherein the flow rate of the discharge fluid discharged through the first discharge device is monitored by a first flow meter and a first pressure monitoring device, the first flow meter and the first pressure monitoring device transmitting information to a controller for calculating the discharge flow rate, the controller communicating with a first adjustable flow control device for controlling the flow rate of the discharge fluid discharged through the first discharge device based on the calculated discharge flow rate, and wherein the flow rate of the discharge fluid discharged through the second discharge device is monitored by a second flow meter and a second pressure monitoring device, the second flow meter and the second pressure monitoring device transmitting information to a controller for calculating the discharge flow rate, the controller communicating with a second adjustable flow control device for controlling the flow rate of the discharge fluid discharged through the second discharge device based on the calculated discharge flow rate.

18. The method as claimed in any of the preceding claims, wherein the forming surface is inclined relative to a horizontal plane.

19. The method of any of the preceding claims, wherein the foamed suspension of the material is formed by combining foam with fiber ingredients, the foam having a density of about 200 g / L to about 600 g / L, such as about 350 g / L to about 600 g / L, and / or containing about 40 vol% to about 80 vol% of air, such as about 40 vol% to about 65 vol% of air.

20. The method of any of the preceding claims, wherein the material in the web comprises at least about 5% by weight pulp fiber, such as at least about 10% by weight pulp fiber, such as at least about 15% by weight pulp fiber, the pulp fiber optionally being combined with non-fiber particles such as superabsorbent particles.

21. The method of any of the preceding claims, wherein the material in the web comprises at least about 5% by weight of polymeric synthetic fibers, such as at least about 10% by weight of polymeric synthetic fibers, such as at least about 15% by weight of polymeric synthetic fibers.

22. The method of claim 1, wherein the dried web has a density greater than about 0.03 g / cc, such as greater than about 0.05 g / cc, such as greater than about 0.1 g / cc, and less than about 0.7 g / cc, such as less than about 0.5 g / cc.

23. The method of claim 1, wherein the dried web has a basis weight of about 6 gsm to about 800 gsm, such as about 10 gsm to about 200 gsm, such as about 20 gsm to about 120 gsm.

24. The method of any of the preceding claims, wherein the fluid discharged through the first discharge device is monitored downstream of the forming surface by at least one of a flow meter, a temperature monitoring device, and a pressure monitoring device, and wherein information received from at least one of the flow meter, the pressure monitoring device, or the temperature monitoring device is used to calculate the flow rate of the fluid discharged through the first discharge device at the forming surface, and wherein the fluid discharged through the second discharge device is also monitored downstream of the forming surface by at least one of the flow meter, the temperature monitoring device, and the pressure monitoring device, and wherein information received from at least one of the flow meter, the pressure monitoring device, or the temperature monitoring device is used to calculate the flow rate of the fluid discharged through the second discharge device at the forming surface.

25. The method of any of the preceding claims, wherein the first emission device and the second emission device comprise a vacuum chamber.

26. The method of any one of claims 1 to 24, wherein the first discharge device and the second discharge device comprise discharge rollers.

27. A system for producing webs, comprising: A first forming zone is positioned relative to at least one porous forming surface and is connected to a foamed fiber supply line, the foamed fiber supply line including a pumping device for flowing a foamed suspension of material to the corresponding first forming zone, the first forming zone being configured to form only a single-layer web. A first discharge device is positioned relative to the at least one porous forming surface and aligned with the first forming area, and the first discharge device is in fluid communication with a first corresponding discharge pipeline. as well as A second discharge device is adjacent to the first discharge device and is also positioned relative to the at least one porous forming surface and aligned with the first forming area. The second discharge device is in fluid communication with a second corresponding discharge pipeline.

28. The system of claim 27, wherein the foamed fiber supply line further comprises a flow meter, a pressure monitoring device, a temperature monitoring device, or a combination thereof, the foamed fiber supply line being used to feed a foamed suspension of material into a corresponding forming zone for depositing the material contained in the foamed suspension onto the vicinity of the at least one porous forming surface at a defined flow rate, temperature, pressure, or a combination thereof, and wherein the first discharge line comprises a first flow control device for controlling the flow rate of fluid discharged into the first discharge device, the first discharge line further comprising a first flow meter, a first pressure monitoring device, a first temperature monitoring device, or a combination thereof. The system comprises a combination thereof, wherein the second discharge line includes a second flow control device for controlling the flow rate of fluid discharged into the second discharge device, the second discharge line also includes a second flow meter, a second pressure monitoring device, a second temperature monitoring device, or a combination thereof, and the system further includes one or more controllers in communication with the flow control devices associated with the first discharge line and the second discharge line, the one or more controllers being configured to control the flow rate of fluid discharged into the first discharge device and the second discharge device relative to the flow rate, temperature, or pressure of the foamed suspension of material fed into the first forming zone.

29. The system of claim 27 or 28, comprising a plurality of forming zones, each forming zone being connected to a separate foam fiber supply line, each foam fiber supply line including a pumping device for flowing a foamed suspension of material to the corresponding forming zone, each foam fiber supply line further including a flow meter, a pressure monitoring device, a temperature monitoring device, or a combination thereof, each foam fiber supply line being used to feed a foamed suspension of material to the corresponding forming zone for depositing the material contained in the foamed suspension onto the vicinity of the at least one porous forming surface at a defined flow rate, temperature, pressure, or both, each forming zone forming a separate layer in a multilayer web on the at least one porous forming surface; For each forming zone, there is at least one corresponding discharge device, each discharge device is in fluid communication with a corresponding discharge pipeline, each discharge pipeline includes a flow control device for controlling the flow rate of the fluid discharged into each corresponding discharge device, and each discharge pipeline also includes a flow meter, a pressure monitoring device, a temperature monitoring device, or a combination thereof; and The one or more controllers communicate with each of the flow control devices associated with the discharge line, and the one or more controllers are configured to independently control the flow rate of the fluid discharged to each discharge device relative to the flow rate, temperature, or pressure of the foamed suspension of material fed into each forming zone in the forming zone.

30. The system of claim 29, wherein the one or more controllers are configured to control the flow rate of the fluid discharged from each discharge device based on information received from a corresponding flow meter, pressure monitoring device and / or temperature monitoring device associated with each forming zone.

31. The system of claim 27, 28, 29 or 30, further comprising a drying device positioned downstream for drying the web formed on the porous shaped surface.

32. The system of any one of claims 27 to 31, wherein the first forming region has a length, and wherein at least one of the first discharge device or the second discharge device extends beyond the length of the first forming region.

33. A method for producing webs, comprising: The foamed suspension of the material is flowed to at least one forming zone, the foamed suspension being fed into the first forming zone at a first flow rate; The foamed suspension of the material fed into the first forming zone is deposited near at least one moving porous forming surface to form an initial web layer; Excess fluid is discharged through the porous forming surface to a first discharge device and a second discharge device, the first discharge device and the second discharge device being positioned aligned with the first forming area along the at least one porous forming surface; as well as The flow rate of the discharge fluid discharged through the first discharge device and the flow rate of the discharge fluid discharged through the second discharge device are controlled, wherein the flow rate of the discharge fluid discharged through the first discharge device and the flow rate of the discharge fluid discharged through the second discharge device are controlled based on at least one characteristic of the flow of the foamed suspension of the material fed into the first forming zone, wherein the at least one characteristic of the flow of the foamed suspension of the material includes the temperature, pressure, mass flow rate, volumetric flow rate or density of the foamed suspension of the material.

34. The method of claim 33, wherein the flow rate of the discharge fluid discharged through the first discharge device is controlled independently of the flow rate of the discharge fluid discharged through the second discharge device.

35. The method of claim 33, wherein the first discharge device is positioned upstream of and adjacent to the second discharge device, and wherein the flow rate of the discharge fluid discharged through the first discharge device is greater than the flow rate of the discharge fluid discharged through the second discharge device.

36. The method of claim 33, wherein the first discharge device is positioned upstream of and adjacent to the second discharge device, and wherein the flow rate of the discharge fluid discharged through the first discharge device is less than the flow rate of the discharge fluid discharged through the second discharge device.

37. The method of claim 33, wherein the flow rate of the discharged fluid discharged through the first discharge device and the flow rate of the discharged fluid discharged through the second discharge device are substantially the same, such that the difference between the flow rate of the discharged fluid discharged through the first discharge device and the flow rate of the discharged fluid discharged through the second discharge device does not exceed about 20%, such as not exceeding about 15%, such as not exceeding about 10%, such as not exceeding about 5%, such as not exceeding about 3%.

38. The method of claim 33, further comprising the step of flowing the foamed suspension of the material to a second forming region located adjacent to the first forming region, wherein the foamed suspension of the material is fed into the second forming region at a second flow rate; The foamed suspension of material to be fed into the second forming zone is deposited near the at least one movable porous forming surface, such that a second layer of material is formed below or above the material deposited from the first forming zone near the forming surface to form a multilayer web; and The flow rate of the discharged fluid through a third discharge device is controlled, the third discharge device being positioned to align with the second forming zone.

39. The method of claim 38, further comprising the step of flowing the foamed suspension of the material to a third forming zone located in a forming zone adjacent to other forming zones, wherein the foamed suspension of the material is fed into the third forming zone at a third flow rate; The foamed suspension of the material to be fed into the third forming zone is deposited near the at least one moving porous forming surface, such that a third layer of material is formed in the multilayer web; and The flow rate of the discharged fluid discharged through the fourth discharge device is controlled, the fourth discharge device being positioned to align with the third forming zone.

40. The method of claim 33, wherein the first forming region has a length, and wherein at least one of the first discharge device or the second discharge device extends beyond the length of the first forming region.

41. The method of claim 33, 38 or 39, wherein the foamed suspension of the material is pumped individually to each forming zone, such that the fluid pressure upstream of each forming zone can be controlled independently of the other forming zones.

42. The method of claim 33, wherein the foamed suspension of the material is pumped to the first forming zone, and wherein prior to the first forming zone, the temperature, pressure, flow rate, and density of the foamed suspension of the material are determined to calculate the flow rate at the forming surface, and the flow rate of the discharged fluid discharged through the first and second discharge devices is controlled based on the calculated flow rate.

43. The method of claim 33, wherein the flow rate of the discharged fluid discharged through the first discharge device is monitored by a first flow meter and a first pressure monitoring device, the first flow meter and the first pressure monitoring device transmitting information to a controller that calculates the discharge flow rate, the controller communicating with a first adjustable flow control device for controlling the flow rate of the discharged fluid discharged through the first discharge device based on the calculated discharge flow rate, and wherein the flow rate of the discharged fluid discharged through the second discharge device is monitored by a second flow meter and a second pressure monitoring device, the second flow meter and the second pressure monitoring device transmitting information to a controller that calculates the discharge flow rate, the controller communicating with a second adjustable flow control device for controlling the flow rate of the discharged fluid discharged through the second discharge device based on the calculated discharge flow rate.

44. The method of claim 33, wherein the material in the web comprises at least about 5% by weight pulp fiber, such as at least about 10% by weight pulp fiber, such as at least about 15% by weight pulp fiber, said pulp fiber optionally combined with non-fiber particles such as superabsorbent particles.

45. The method of claim 33, wherein the fluid discharged through the first discharge device is monitored downstream of the forming surface by at least one of a flow meter, a temperature monitoring device, and a pressure monitoring device, and wherein information received from at least one of the flow meter, the pressure monitoring device, or the temperature monitoring device is used to calculate the flow rate of the fluid discharged through the first discharge device at the forming surface, and wherein the fluid discharged through the second discharge device is also monitored downstream of the forming surface by at least one of the flow meter, the temperature monitoring device, and the pressure monitoring device, and wherein information received from at least one of the flow meter, the pressure monitoring device, or the temperature monitoring device is used to calculate the flow rate of the fluid discharged through the second discharge device at the forming surface.

46. ​​The method of claim 33, wherein at least one of the layers of the initial web is a unique layer formed at the corresponding forming region.

47. The method of claim 33, wherein a single layer of the initial web is formed at the corresponding forming region.

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