Foam forming system with angled dividing lamella

Abstract

A process and system for foam forming webs is disclosed. The method includes depositing a first foamed suspension of fibers onto a forming surface while the forming surface is moving in order to form an embryonic web and depositing a second foamed suspension of fibers onto the embryonic web while the forming surface is moving in order to form another layer on the embryonic web. An angled end of the dividing lamella directs a flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella substantially parallel to the forming surface.

Description

[0001] FOAM FORMING SYSTEM WITH ANGLED DIVIDING LAMELLA

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] The present application claims priority to and benefit of United States Provisional Patent Application 63 / 578,379 having a filing date of August 24, 2023, which is hereby incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] Many tissue products, such as facial tissue, bath tissue, paper towels, industrial wipers, and the like, are produced according to wet laid processes. Wet laid webs are made by depositing an aqueous suspension of pulp fibers onto a forming fabric and then removing water from the newly- formed web.

[0006] In order to improve various characteristics of tissue webs, webs have also been formed according to foam forming processes. During a foam forming process, a foamed suspension of fibers is created and spread onto a moving porous conveyor for producing an embryonic web. Foam formed webs can demonstrate improvements in bulk, stretch, caliper, and / or absorbency. In addition to tissue webs, foam forming can be used to make all different types of webs and products. For example, relatively long fibers and synthetic fibers can be incorporated into webs using a foam forming process. Thus, foam forming processes can be more versatile than many wet laid processes.

[0007] Foam forming a multi-layer web can pose challenges. For instance, balancing slurry flows within a headbox to form uniform webs can be difficult. In some headboxes, slurry flows may impinge against an embryonic web and form defects.

[0008] A system and method for improved foam flow within a headbox would be useful. For instance, a system and method for improved foam flow between adjacent foam forming volumes in a headbox for forming multi-layer webs would be useful.

[0009] SUMMARY

[0010] In general, the present disclosure is directed to a system and method for foam forming a nonwoven web. A headbox includes a dividing lamella positioned between a first forming zone and a second forming zone in the headbox. The dividing lamella includes an angled end positioned at a forming surface. The angled end of the dividing lamella is oriented substantially parallel to the forming surface. By angling the end of the dividing lamella substantially parallel to the forming surface, the dividing lamella can assist with controlling shear stress in flows of foamed suspension of fibers in the first and second forming zones. For instance, the angled end of the dividing lamella may assist with limiting or preventing disruption in an embryonic layer on the forming surface as the embryonic layer passes from the first forming zone into the second forming zone proximate the angled end of the dividing lamella. The angled end of the dividing lamella may also assist the forming a web with improved cross-machine direction basis weight uniformity, e.g., relative to dividing lamella without the angled end.

[0011] A vacuum drawn through the forming surface at the angled end of the dividing lamella may also be controlled to avoid defects in the embryonic web. Moreover, the vacuum through the forming surface may be reduced proximate the angled end of the dividing lamella relative to adjacent portions of the forming surface. For instance, the vacuum dewatering box may be blocked or restricted at the angled end of the dividing lamella. Reducing the vacuum proximate the angled end of the dividing lamella may assist with limiting or preventing disruption in an embryonic layer on the forming surface as the embryonic layer passes from the first forming zone into the second forming zone proximate the angled end of the dividing lamella. Reducing the vacuum proximate the angled end of the dividing lamella may also assist with forming a web with improved cross-machine direction basis weight uniformity, e.g., relative to a uniform vacuum along a machine direction.

[0012] In one example embodiment, a system for producing webs includes a forming surface. A headbox is positioned adjacent the forming surface. The headbox includes a first forming zone and a second forming zone. The first forming zone is configured for directing a first foamed suspension of fibers onto the forming surface. The second forming zone is configured for directing a second foamed suspension of fibers onto the forming surface. A dividing lamella is disposed within the headbox between the first and second forming zones. The dividing lamella includes an angled end positioned at the forming surface. The angled end of the dividing lamella is oriented substantially parallel to the forming surface.

[0013] In another example embodiment, a method for producing webs includes flowing a first foamed suspension of fibers into a first forming zone of a headbox and flowing a second foamed suspension of fibers into a second forming zone of a headbox. The second forming zone is separated from the first forming zone within the headbox by a dividing lamella. The dividing lamella includes an angled end positioned at a forming surface. The angled end of the dividing lamella is oriented substantially parallel to the forming surface. The method also includes depositing the first foamed suspension of fibers onto the forming surface while the forming surface is moving in order to form an embryonic web and depositing the second foamed suspension of fibers onto the embryonic web while the forming surface is moving in order to form another layer on the embryonic web. The angled end of the dividing lamella directs a flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella substantially parallel to the forming surface.

[0014] Other features and aspects of the present disclosure are discussed in greater detail below.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

[0017] FIG. 1 is a schematic view of a system and process according to an example embodiment of the present disclosure for forming webs from a foamed suspension of materials;

[0018] FIG. 2 is a schematic view of a system and process according to an example embodiment of the present disclosure for depositing a foamed suspension of materials onto a forming surface in accordance with the present disclosure;

[0019] FIG. 3 is a schematic view of a system and process according to an example embodiment of the present disclosure for directing a foamed suspension of materials generally parallel to a forming surface during foam forming of a non-woven web.

[0020] FIG. 4 is a schematic view of certain components of the example system and process of FIG. 3;

[0021] FIG. 5 is another schematic view of the example system and process of FIG. 4 with a dividing lamella moved relative to FIG. 3; and

[0022] FIG. 6 is a flow diagram of a process according to an example embodiment of the present disclosure for foam forming of a non-woven web.

[0023] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

[0024] DEFINITIONS

[0025] When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, "an”, "the” and "said” are intended to mean that there are one or more of the elements. As used herein, the terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e. , “A or B" is intended to mean “A or B or both”). Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. For example, the approximating language may refer to being within a ten percent (10%) margin. As used herein, the term “foam formed product” means a product formed from a suspension including a mixture of a solid, a liquid, and dispersed gas bubbles.

[0026] As used herein, the term “foam forming process” means a process for manufacturing a product involving a suspension including a mixture of a solid, a liquid, and dispersed gas bubbles.

[0027] As used herein, the term “foaming fluid” means any one or more known fluids compatible with the other components in the foam forming process. Suitable foaming fluids include, but are not limited to, water.

[0028] As used herein, the term “foam half life” means the time elapsed until the half of the initial foam mass reverts to liquid water

[0029] As used herein, the term “layer" refers to a structure that provides an area of a substrate in a height direction of the substrate that is comprised of similar components and structure.

[0030] As used herein, the term "nonwoven web" means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted web.

[0031] As used herein, unless expressly indicated otherwise, when used in relation to material compositions the terms "percent", “%”, "weight percent", or "percent by weight" each refer to the quantity by weight of a component as a percentage of the total except as whether expressly noted otherwise.

[0032] The term "superabsorbent material" as used herein refers to water-swellable, water-insoluble organic or inorganic materials including superabsorbent polymers and superabsorbent polymer compositions capable, under the most favorable conditions, of absorbing at least about ten times (1 OX) their weight, or at least about fifteen times (15X) their weight, or at least about twenty-five times (25X) their weight in an aqueous solution containing nine-tenths (0.9) weight percent sodium chloride.

[0033] The term "machine direction" as used herein refers to the direction of travel of the forming surface onto which fibers are deposited during formation of a nonwoven web.

[0034] The term "cross-machine direction" as used herein refers to the direction which is perpendicular to the machine direction defined above.

[0035] The term "pulp" as used herein refers to fibers from natural sources such as woody and non- woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, milkweed, straw, jute, hemp, and bagasse. Pulp fibers may include hardwood fibers, softwood fibers, and mixtures thereof.

[0036] The term "average fiber length" as used herein refers to an average length of fibers, fiber bundles and / or fiber-like materials determined by measurement utilizing microscopic techniques. A sample of at least 20 randomly selected fibers is separated from a liquid suspension of fibers. The fibers are set up on a microscope slide prepared to suspend the fibers in water. A tinting dye is added to the suspended fibers to color cellulose-contain ing fibers so they may be distinguished or separated from synthetic fibers. The slide is placed under a Fisher Stereomaster II Microscope-S19642 / S19643 Series. Measurements of 20 fibers in the sample are made at 20X linear magnification utilizing a 0-20 mils scale and an average length, minimum and maximum length, and a deviation or coefficient of variation are calculated. In some cases, the average fiber length will be calculated as a weighted average length of fibers (e.g., fibers, fiber bundles, fiber-like materials) determined by equipment such as, for example, a Kajaani fiber analyzer Model No. FS-200, available from Kajaani Oy Electronics, Kajaani, Finland. According to a standard test procedure, a sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each sample is disintegrated into hot water and diluted to an approximately 0.001% suspension. Individual test samples are drawn in approximately 50 to 100 ml portions from the dilute suspension when tested using the standard Kajaani fiber analysis test procedure. The weighted average fiber length may be an arithmetic average, a length weighted average or a weight weighted average and may be expressed by the following equation: where k=maximum fiber length

[0037] X fiber length npnumber of fibers having length xi n=total number of fibers measured.

[0038] One characteristic of the average fiber length data measured by the Kajaani fiber analyzer is that it does not discriminate between different types of fibers. Thus, the average length represents an average based on lengths of all different types, if any, of fibers in the sample.

[0039] As used herein the term "staple fibers" means discontinuous fibers made from synthetic polymers such as polypropylene, polyester, post consumer recycle (PCR) fibers, polyester, nylon, and the like, and those not hydrophilic may be treated to be hydrophilic. Staple fibers may be cut fibers or the like. Staple fibers can have cross-sections that are round, bicomponent, multicomponent, shaped, hollow, or the like. DETAILED DESCRIPTION

[0040] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0041] In general, the present disclosure is directed to a system and method for foam forming a nonwoven web. The systems and method of the present disclosure may advantageously assist with foam forming a multi-layer web. Slurry flows from first and second forming sections of a headbox onto a forming surface may be balanced to assist with uniform web formation. Moreover, shear forces in the slurry flows may be regulated to assist with reducing or preventing defects in the nonwoven web. As a first example, excessive dewatering may be avoided to prevent the slurry from the second forming section from flowing around an edge of a dividing lamella between the first and second forming sections, which can disrupt the embryonic web from the first forming section that has already been drained and has little wet strength. Thus, defects, such as "eyebrows”, where the slurry from the second forming section disrupts the newly formed, but yet undried / unbonded embryonic web can be limited or prevented. As a second example, when the embryonic web from the first forming section is underdrained, foamed slurry from the first forming section above the embryonic web can flow underneath the dividing lamella. When there is enough shear force, the embryonic web can be disrupted leading to major defects. When the slurry in the second forming section includes superabsorbent material, shear force related defects in the embryonic web can expose the superabsorbent material to the forming surface, which can allow the superabsorbent material to pass through the forming surface and / or fall out of the embryonic web in various parts of the manufacturing and subsequent processing. By balancing slurry flows in the headbox, the present subject matter may advantageously assist with avoiding the defects described above in order to foam form quality, uniform nonwoven webs.

[0042] To provide balanced slurry flow and avoid shear force related defects, a dividing lamella positioned within a headbox between first and second forming sections may include an angled end positioned adjacent a forming surface. The angled end of the dividing lamella may be positioned and oriented such that the angled end of the dividing lamella directs a flow of a foamed suspension of fibers in the second forming section parallel or substantially parallel to the forming surface. For instance, a top surface of the angled end (e.g., that faces towards the second forming section) may be oriented parallel or substantially parallel to the forming surface. Such arrangement of the angled end of the dividing lamella may advantageously assist with reducing the shear stress between the embryonic web on the forming surface and the layer forming on the embryonic web from the foamed suspension of fibers in the second forming section. Such arrangement of the angled end of the dividing lamella may also advantageously provide increased weight uniformity along a cross-machine direction. Such performance enhancements may be relative to dividing lamella without the angled end, e.g . , a rectilinear dividing lamella.

[0043] A gap between the forming surface and a bottom surface of the angled end facing the forming surface may be sized such that a portion of foamed suspension of fibers in the first forming section flows between the forming surface and the dividing lamella towards the second forming section, e.g., rather than being drained through the forming surface for the embryonic web. In the second forming section, the foamed suspension of fibers from the first forming section that passes between the forming surface and the dividing lamella may act as a buffer for the embryonic web against the flow of the foamed suspension of fibers in the second forming section. Advantageously, such buffer may dissipate shear forces due to speed and / or direction differences between the embryonic web on the forming surface and the flow of the foamed suspension of fibers in the second forming section that is forming the layer on the embryonic web at the second forming section.

[0044] The gap between the forming surface and the bottom surface of the angled end facing the forming surface may also be sized such a velocity of the foamed suspension of fibers from the first forming section passing through the gap into the second forming section is selected to match a velocity of the foamed suspension of fibers from the second forming section at the angled end of the dividing lamella. Such velocity matching may advantageously assist with enhancing layer purity. Moreover, the shear forces (mixing) resulting from a speed difference between forming surface and the flow speed of the layer forming on the embryonic web from the foamed suspension of fibers in the second forming section may be contained within the foamed suspension of fibers from the first forming section entering the second forming section through the gap.

[0045] Dewatering of the embryonic web may also be limited at the gap between the forming surface and the bottom surface of the angled end facing the forming surface. For instance, a drainage vacuum under the angled end of the dividing lamella running parallel or near parallel to the forming surface may be at least partially blocked or omitted. Limiting vacuum dewatering proximate the angled end facing the forming surface may advantageously assist with limiting or preventing exposure of superabsorbent material to the forming surface, as described above.

[0046] In example embodiments, the present subject matter may provide a multi-layered incline or twin-wire foam-forming system with drainage zones correlated to divider locations between adjacent forming sections within a headbox. Moreover, the present subject matter may provide tight control over supply and drainage flows in the first and second formation zones in the headbox. Foam-forming allows for higher speed mismatches between the formation surface and the forming flows than conventional wet-laying processes by using a high viscosity, shear thinning medium. Large speed mismatches may be required when utilizing superabsorbent material in the foam forming process to limit exposure time of the superabsorbent material to liquid. The angled end of the dividing lamella in combination with a converging flow section for the first formation section in the headbox, which controls the forming speed above the forming surface, and tight control over supply and drainage flows in a multi-layered inclined foam-former may advantageously assist with managing shears stresses during web formation and avoid defects.

[0047] Referring to FIGS. 1 and 2, an example embodiment of a system and process in accordance with aspects of the present disclosure is shown. In general, during the process, solid material, such as fibers and / or superabsorbent particles, water, and a foam forming agent are added to a tank and mixed until the desired air content, bubble size / foam stability, and solid dispersion are achieved, such as a fiber dispersion. The fiber-containing foam may then optionally be diluted during the process, especially when a recycle stream is present. In one example aspect, the air content of the foamed suspension is between about thirty percent (30%) and about sixty-five percent (65%). As will be described below, example aspects of the process and system of the present disclosure are directed to separating foam from free air and managing foam, e.g ., during foam forming of a nonwoven web.

[0048] FIG. 1 illustrates a system and process for producing a foamed suspension of fibers and for forming webs from the foamed suspension of fibers. It will be understood that the example system shown in FIG. 1 is provided by way of example and that any suitable web forming system may be used in accordance with the present disclosure. As shown in FIG. 1 , the system may include a mixing tank 12 configured to form the foamed suspension of fibers. The foamed suspension of fibers may then be fed to a headbox or web forming system 10 that deposits the foamed suspension of fibers onto a porous forming fabric or surface 26 for forming a web 14. The mixing tank 12 may be in communication with a water supply 22 for feeding water to the tank and a foaming agent or surfactant supply 24 for feeding a surfactant to the tank 12. A fiber furnish may also be fed to the tank 12 and combined with the water and surfactant. The aqueous solution formed by combining the surfactant and water may be agitated and formed into a foam for forming a foamed suspension of fibers. As described above, in addition to fibers, various other materials may be combined in the tank 12. Such other materials, for instance, may include superabsorbent particles or the like.

[0049] The surfactant or foaming agent, for instance, may include any suitable surfactant. In one example embodiment, for instance, the foaming agent may include sodium lauryl sulfate, which is also known as sodium laureth sulfate or sodium lauryl ether sulfate. Other foaming agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other example embodiments, the foaming agent may include any suitable cationic and / or amphoteric surfactant. For instance, other foaming agents include fatty acid amines, amides, amine oxides, fatty acid quaternary compounds, and the like. In one example embodiment, a nonionic surfactant is used. The nonionic surfactant, for instance, may include an alkyl polyglycoside. In one aspect, for instance, the surfactant may be a C8 alkyl polyglycoside, a C10 alkyl polyglycoside, or a mixture of C8 and C10 alkyl polyglycosides.

[0050] The foaming agent may be combined with water generally in an amount greater than about one-tenth of a percent (0.1%) by weight, such as in an amount greater than about half of a percent (0.5%) by weight, such as in an amount greater than about seven-tenths of a percent (0.7%) by weight. One or more foaming agents may generally be present in an amount of from about one- hundredth of a percent (0.01 %) by weight to about five percent (5%) by weight, such as in an amount up to about two percent (2%) by weight.

[0051] When the foaming agent and water are combined, the mixture may be blended or otherwise subjected to forces capable of forming a foam. A foam generally refers is an aggregate of hollow cells or bubbles.

[0052] The foam density can vary depending upon the particular application and various factors including the fiber furnish used. In one example embodiment, for instance, the foam density of the foam may be greater than about two hundred grams per liter (200 g / L), such as greater than about two hundred and fifty grams per liter (250 g / L), such as greater than about three hundred grams per liter (300 g / L). The foam density is generally less than about six hundred grams per liter (600 g / L), such as less than about five hundred grams per liter (500 g / L), such as less than about four hundred grams per liter (400 g / L), such as less than about three hundred and fifty grams per liter (350 g / L). In one example embodiment, for instance, a lower density foam is used having a foam density of generally less than about three hundred and fifty grams per liter (350 g / L), such as less than about three hundred and forty grams per liter (340 g / L), such as less than about three hundred and thirty grams per liter (330 g / L). The foam may generally have an air content of greater than about forty percent (40%), such as greater than about fifty percent (50%), such as greater than about sixty percent (60%), e.g. , at standard temperature and pressure (STP). The air content is generally less than about seventy-five percent (75%) by volume, such as less than about seventy percent (70%) by volume, such as less than about sixty-five percent (65%) by volume.

[0053] The foam may be formed in the presence of a fiber furnish or, alternatively, the foam may first be formed and then combined with a fiber furnish. In general, any fibers capable of making a basesheet, such as a tissue web or other similar type of nonwoven, may be used. Fibers suitable for making webs include any natural or synthetic cellulosic fibers including, but not limited to: nonwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, and pineapple leaf fibers; and woody or pulp fibers, such as those obtained from deciduous and coniferous trees, including softwood fibers, such as northern and southern softwood kraft fibers; hardwood fibers, such as eucalyptus, maple, birch, and aspen. Pulp fibers may be prepared in high-yield or low-yield forms and may be pulped in any known method, including kraft, sulfite, high-yield pulping methods and other known pulping methods. Fibers prepared from organosolv pulping methods may also be used.

[0054] A portion of the fibers, such as up to one hundred percent (100%) or less by dry weight, or from about five percent (5%) to about thirty percent (30%) by dry weight, may be synthetic fibers, such as rayon, polyolefin fibers, polyester fibers, bicomponent sheath-core fibers, multi-component binder fibers, and the like. The fibers may be virgin fibers or recycled fibers. The fibers may be staple fibers and may have an average length of from about three millimeters (3 mm) to about one hundred and fifty millimeters (150 mm). An exemplary polyethylene fiber is Fybrel®, available from Minifibers, Inc. (Jackson City, Tenn.). When containing synthetic polymer fibers, the web may be thermally bonded where the fibers intersect.

[0055] Synthetic cellulose fiber types include rayon in all its varieties and other fibers derived from viscose or chemically-modified cellulose. Chemically treated natural cellulosic fibers may be used, such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers. For good mechanical properties in using papermaking fibers, it may be desirable that the fibers be relatively undamaged and largely unrefined or only lightly refined. While recycled fibers may be used, virgin fibers are generally useful for their mechanical properties and lack of contaminants. Mercerized fibers, regenerated cellulosic fibers, cellulose produced by microbes, rayon, and other cellulosic material or cellulosic derivatives may be used. Suitable papermaking fibers may also include recycled fibers, virgin fibers, or mixes thereof. In certain example embodiments capable of high bulk and good compressive properties, the fibers may have a Canadian Standard Freeness of at least two hundred (200), more specifically at least three hundred (300), more specifically still at least four hundred (400), and most specifically at least five hundred (500).

[0056] Other papermaking fibers that may be used include paper broke or recycled fibers and high yield fibers. High yield pulp fibers are those papermaking fibers produced by pulping processes providing a yield of about sixty-five percent (65%) or greater, more specifically about seventy-five percent (75%) or greater, and still more specifically about seventy-five percent (75%) to about ninety- five percent (95%). Yield is the resulting amount of processed fibers expressed as a percentage of the initial wood mass. Such pulping processes include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which leave the resulting fibers with high levels of lignin. High yield fibers are well known for their stiffness in both dry and wet states relative to typical chemically pulped fibers.

[0057] The web may also be formed without a substantial amount of inner fi ber-to-fi ber bond strength. In this regard, the fiber furnish used to form the base web may be treated with a chemical debonding agent. The debonding agent may be added to the foamed fiber slurry during the pulping process or may be added directly to the headbox. Suitable debonding agents that may be used include cationic debonding agents, such as fatty dialkyl quaternary amine salts, mono fatty alkyl tertiary amine salts, primary amine salts, imidazoline quaternary salts, silicone quaternary salt and unsaturated fatty alkyl amine salts. Other suitable debonding agents are disclosed in U.S. Pat. No. 5,529,665 to Kaun, the entirety of which is incorporated herein by reference. In particular, Kaun discloses the use of cationic silicone compositions as debonding agents.

[0058] In one example embodiment, the debonding agent used in the process of the present disclosure may be an organic quaternary ammonium chloride and, particularly, a silicone-based amine salt of a quaternary ammonium chloride. For example, the debonding agent may be PROSOFT.RTM. TQ1003, marketed by the Hercules Corporation. The debonding agent may be added to the fiber slurry in an amount of from about one kilogram per metric ton (1 kg / tonne) to about ten kilograms per metric ton (10 kg / tonne) of fibers present within the slurry.

[0059] In an alternative example embodiment, the debonding agent may be an imidazoline-based agent. The imidazoline-based debonding agent may be obtained, for instance, from the Witco Corporation. The imidazoline-based debonding agent may be added in an amount of between two kilograms per metric ton (2.0 kg / tonne) to about fifteen kilograms per metric ton (15 kg / tonne).

[0060] Other optional chemical additives may also be added to the aqueous papermaking furnish or to the formed embryonic web to impart additional benefits to the product and process. The following materials are included as examples of additional chemicals that may be applied to the web. The chemicals are included as examples and are not intended to limit the scope of the disclosure. Such chemicals may be added at any point in the papermaking process.

[0061] Additional types of chemicals that may be added to the paper web include, but are not limited to, absorbency aids usually in the form of cationic, anionic, or non-ionic surfactants, humectants and plasticizers, such as low molecular weight polyethylene glycols, and polyhydroxy compounds, such as glycerin and propylene glycol. Materials that supply skin health benefits, such as mineral oil, aloe extract, vitamin E, silicone, lotions in general and the like, may also be incorporated into the finished products.

[0062] Other examples of such materials include but are not limited to odor control agents, such as odor absorbents, activated carbon fibers and particles, baby powder, baking soda, chelating agents, zeolites, perfumes or other odor-masking agents, cyclodextrin compounds, oxidizers, and the like. Superabsorbent particles may also be employed. Additional options include cationic dyes, optical brighteners, humectants, emollients, and the like.

[0063] Turning to FIG. 2, once the foamed suspension of fibers is formed in the tank 12 (FIG. 1), the foamed suspension of fibers may be fed to the web forming system 10. As illustrated in FIG. 2, the web forming system 10 may include includes one or more forming zones. In the example embodiment of FIG. 2, three forming zones are shown, including first forming zone 50, second forming zone 52, and third forming zone 54. The forming zones 50, 52, and 54 are positioned along the porous forming surface 26. In one example embodiment, as shown in FIG. 2, the porous forming surface 26 may be at an incline with respect to horizontal. For instance, the porous forming surface 26 may be oriented at an angle with the horizontal of greater than about ten degrees (10°), such as greater than about twenty degrees (20°), such as greater than about thirty degrees (30°), and generally less than about sixty degrees (60°), such as less than about fifty degrees (50°). Each forming zone 50, 52, and 54 may be configured to receive a separate and independent flow of the foamed suspension of fibers for depositing the foamed suspension of fibers onto the forming surface 26. For instance, the first forming zone 50 may deposit a foamed suspension of fibers directly onto the forming surface 26. The second forming zone 52, however, may be configured to deposit a second flow rate of the foamed suspension of fibers on top of the fibers deposited by the first forming zone 50. Similarly, the third forming zone 54 may deposit a flow of the aqueous suspension of fibers on top of the fibers deposited by the first forming zone 50 and the second forming zone 52. In this manner, a multilayered web may be formed. It should be understood, however, that the system and process of the present disclosure may include only a single forming zone for forming single layered webs.

[0064] As shown in FIG. 2, each forming zone 50, 52, and 54 may be in fluid communication with a separate and independent foamed fibrous supply line. For instance, first forming zone 50 may be in communication with a first foamed fibrous supply line 56, the second forming zone 52 may be in fluid communication with a second foamed fibrous supply line 58, and the third forming zone 54 may be in fluid communication with a third foamed fibrous supply line 60. The first, second, and third supply lines 56, 58, and 60 may be configured to feed a foamed suspension of fibers to each of the respective forming zones 50, 52, and 54 at a determined and selected flow characteristic, which may be, for instance, flow rate, such as volumetric flow rate, pressure, air content, and / or density. In this regard, each of the supply lines 56, 58, and 60 may be in fluid communication with the mixing tank 12 as shown in FIG. 1 . For instance, the first supply line 56 may include a first injection line 62 that is connected to the mixing tank 12. Similarly, the second supply line 58 may include a second injection line 64, while the third supply line 60 may be in communication with a third injection line 66. The injections lines 62, 64, and 66 may all be in communication with the mixing tank 12 for feeding the foamed suspension of fibers to each of the forming zones 50, 52, and 54. Alternatively, the system 10 may include separate mixing tanks, and each of the first, second, and third injection lines 62, 64, and 66 may be connected to a different, respective mixing tank for feeding the foamed suspension of fibers to the web forming system 10.

[0065] As shown, each of the foamed fibrous 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 fibrous supply line 56, 58, and 60 may also be in communication with a density monitoring device. The density monitoring device, for instance, may be part of one of the other devices, such as part of the flow meter. Alternatively, the density of the foamed suspension of fibers may be calculated using information received from the other instruments.

[0066] For example: the first foamed fibrous supply line may include a first pumping device 68, a first flow meter 74, a first pressure monitoring device 80, and a first temperature monitoring device 81 ; the second foamed fibrous supply line 58 may include a second pumping device 70, a second flow meter 76, a second pressure monitoring device 82, and a second temperature monitoring device 83; and the third foamed fibrous supply line 60 may include a third pumping device 72, a third flow meter 78, a third pressure monitoring device 84 and a third temperature monitoring device 85. The pumping devices 68, 70, and 72 may be adjustable such that the foamed suspension of fibers may be independently fed to each forming zone 50, 52, and 54 at a desired, selected flow rate and / or pressure. The flow meters 74, 76, and 78, the pressure monitoring devices 80, 82, and 84 (e.g., volumetric flow rate), and the temperature monitoring devices 81 , 83 and 85 may monitor flow rates, pressures, and temperatures upstream from the forming surface for calculating at least one characteristic of the flow of the foamed suspension of fibers at the forming surface.

[0067] In one example embodiment, the flow meters 74, 76, and 78, the pressure monitoring devices 80, 82, and 84, the temperature monitoring devices 81 , 83 and 85 may be placed in communication with one or more controllers. The controllers may include microprocessors or any suitable programmable device. The pumping devices 68, 70, and 72 may also be placed in communication with the one or more controllers. The controllers may be configured to adjust the pumping devices 68, 70, and 72 based upon information received from the flow meters 74, 76, and 78, from the pressure monitoring devices 80, 82, and 84, and / or from the temperature monitoring devices 81 , 83 and 85. In this manner, the foamed suspension of fibers may be fed to each forming zone 50, 52, and 54 at a flow rate within desired set points and / or at a pressure within desired set points for optimizing formation of a web on the forming surface 26.

[0068] Information received from the flow meters 74, 76, and 78, from the pressure monitoring devices 80, 82, and 84, and / or from the temperature monitoring devices 81 , 83, and 85 may be used to determine the characteristics of the foamed suspension of fibers at the location of the measurements. In addition, the density of the foamed suspension of fibers may be measured or calculated from the information received from the various instruments. This information, in one embodiment, may be sent to the controllers for then calculating at least one characteristic of the foamed suspension of fibers at the forming surface. In particular, the controller may be programmed to correct the determined volumetric flow rate at the forming surface based upon changes in density, pressure, and temperature. For example, the foamed suspension can experience a pressure drop when being emitted from the supply line onto the forming surface that changes the density of the foamed suspension. One method for calculating downstream values of the foamed suspension, for instance, is disclosed in U.S. Patent No. 4,764,253, which is incorporated herein by reference.

[0069] As shown in FIG. 2, opposite the first forming zone 50 along the forming surface 26 may be a first drain device 86 in fluid communication with a first drain line 92. Opposite the second forming zone 52 may be a second drain device 88 in fluid communication with a second drain line 94. Similarly, opposite the third forming zone 54 may be a third drain device 90 in communication with a third drain line 96. The first, second, and third forming zones 50, 52, and 54 may be adjacent to one another along the forming surface 26 and may be positioned on one side of the forming surface 26. The drain devices 86, 88, and 90 may also be adjacent to one another and may be positioned on the opposite side of the forming surface 26 in alignment with the forming zones 50, 52, and 54. As the foamed suspension of fibers is deposited onto the forming surface from each forming zone 50, 52, and 54, a web 14 may be formed and excess fluids may enter the corresponding drain devices 86, 88, and 90. The drain devices may be any suitable static or dynamic drain device capable of draining fluids from the web or from the forming surfaces. The drain device may be a static suction or vacuum box. Alternatively, the drain device may be a drum, such as a rotating drum that applies suction.

[0070] As shown in FIG. 2, each drain line 92, 94, and 96 may include a corresponding flow control device, flow meter, temperature monitoring device, and pressure monitoring device. For example: the first drain line 92 may include 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 drain line 94 may include a second flow control device 100, a second flow meter 106, a second temperature monitoring device 107, and a second pressure monitoring device 112; and the third drain line 96 may include a third flow control device 102, a third flow meter 108, a third temperature monitoring device 109, and a third pressure monitoring device 114. The flow control devices 98, 100, and 102 may be any suitable device for controlling flow through the line and may be, an adjustable valve or a pump. Pumps, for instance, may be used to apply suction to the forming surface. Alternatively, draining can occur through gravity. In still another example embodiment, each flow control device 98, 100, and 102 may be a combination of a pump and an adjustable valve

[0071] In one example embodiment, the system 10 may further include one or more controllers 116. The controllers 116 may include microprocessors or any suitable programmable devices. As shown in FIG. 2, 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 may be in communication with the controller 116. The controller 116 may 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 making adjustments to the flow control devices 98, 100, and 102 for controlling the flow rate in which fluids are drained from each of the drain devices 86, 88, and 90. The combination of receiving information from the flow control devices 98, 100, and 102, which may be volumetric flow meters, from the pressure monitoring devices 110, 112, and 114, from the temperature monitoring devices 105, 107, and 109, and / or from optional density monitoring devices may be used to quantify the fluid discharge flows containing both gases and liquids. In one example embodiment, the controller 116 may use the above information to calculate a flow rate, such as a volumetric flow rate, at the forming surface and control the volumetric flow rate based upon at least one characteristic of the foamed suspension being fed to the forming surface. The controller 116 may then control the flow control devices 98, 100, and 102 to achieve a calculated discharge flow rate through each drain device and drain line.

[0072] In example embodiments, the process and system of the present disclosure may further include a sealing zone 120 positioned along the forming surface 26 and in fluid communication with a sealing fluid supply line 122. As shown in FIG. 2, 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 for feeding a fluid, particularly a liquid, to the sealing zone 120. Sealing fluid may be any suitable liquid. For instance, the sealing fluid may be water, a water and surfactant solution, or the like. In one example embodiment, the sealing fluid may be non-fibrous. A sealing fluid may be fed to the sealing fluid zone 120 at a flow rate and / or at a pressure such that sealing fluid deposited onto the forming surface 26 forms a fluid seal that prevents air flow in an upstream longitudinal direction. Information received from the flow meter 126, the pressure monitoring device 128, the temperature monitoring device 129, and optionally a density monitoring device may be used to calculate volumetric flow rates of the foam at the forming surface.

[0073] As shown in FIG. 2, the sealing zone 120 may be positioned upstream from and adjacent to the plurality of forming zones. The sealing zone 120 may also be placed opposite a sealing drain device 130 connected to a sealing drain line 132. The sealing drain line 132 may include a flow control device 134, a flow meter 136, a temperature monitoring device 137, and a pressure sensing device 138 that may all be in communication with the controller 116. In this manner, the flow rate of drainage of the sealing fluid may be controlled based upon the flow rate or pressure at which the sealing fluid enters or exits the sealing zone 120. By including the sealing zone 120, better formation of the web 14 occurs opposite the first forming zone 50.

[0074] The web forming system 10 as shown in FIG. 2 may also include a suction zone 140 adjacent to the plurality of formation zones and positioned downstream from the formation zones. The suction zone 140 may be in fluid communication with a drain line 142 which may include a pressure monitoring device 144. The suction zone 140 is for drawing fluids through the embryonic web 14 after the web has been formed. The suction zone 140 is for removing excess fluids, particularly liquids, from the web 14. In one aspect, the drainage flow rate of the foamed suspension of fibers being drained through the one or more drain devices may be controlled such that excess fluid from the one or more forming zones enters the suction zone 140. Ideally, the suction zone 140 facilitates draining fluids from the web 14 without causing any detrimental effects.

[0075] As shown in FIG. 2, all of the drain lines 92, 94, 96, 132, and 142 may be fed to a separator tank 150. The separator tank 150 may be configured to separate free gases from foam. As shown, the separator tank 150 may include a gas outlet 152 that may be connected to a vacuum source and a liquid outlet 154. The liquid collected in the separator tank 150 may include a water and surfactant mixture. As shown in FIG. 2, a pumping device 156 may be used to pump liquids from the separator tank 150 to a liquid tank 158 which may also be placed in communication with a water source 160. The liquid tank 158 may be used to recycle the water and surfactant mixture back into the process through the supply lines 56, 58, 60, and 122.

[0076] Referring back to FIG. 1 , after the embryonic web 14 is formed from the web forming system or headbox 10, the web 14 may be fed to various different downstream processes. FIG. 1 merely represents one example embodiment of a process for drying the web 14 after being formed. As shown, the web 14 is formed on the forming surface 26 and conveyed downstream. The endless traveling forming surface 26, for instance, may be supported and driven by rolls 28.

[0077] Once formed on the forming surface 26, the formed web 14 may have a consistency of less than about fifty percent (50%), such as less than about twenty percent (20%), such as less than about ten percent (10%), such as less than about five percent (5%). In fact, the forming consistency may be less than about two percent (2%), such as less than about one and eight-tenths percent (1 .8%), such as less than about one and a half percent (1 .5%). The forming consistency is generally greater than about a half percent (0.5%), such as greater than about eight-tenths percent (0.8%).

[0078] Once the wet web 14 is formed on the forming surface 26, the web 14 is conveyed downstream and optionally further dewatered. For instance, the process may optionally include a plurality of vacuum devices 16, such as vacuum and vacuum rolls. The vacuum boxes assist in removing moisture from the newly formed web 14.

[0079] As shown in FIG. 1 , the forming surface 26 may also be placed in communication with a steambox 18 positioned above a pair of vacuum rolls 20. The steambox 18, for instance, may increase dryness and reduce cross-directional moisture variance. The applied steam from the steambox 18 heats the moisture in the wet web 14 causing the water in the web to drain more readily, especially in conjunction with the vacuum rolls 20. From the forming surface 26, the newly formed web 14 is conveyed downstream and dried. The web 14 may be dried using any suitable drying device. For instance, the web 14 may be through-air dried or placed on a heated drying drum and creped or left uncreped. In FIG. 1 , for instance, the formed web 14 is placed in contact with two heated drying drums 38 and 40. In one example embodiment, from the drying drums 38 and 40, the web 14 may be fed to a through-air dryer prior to being wound into a roll.

[0080] The embodiment in FIG. 2 is for forming multilayer webs. In another aspect, the process of the present disclosure may be used to create single layer webs from a foamed suspension of materials.

[0081] Turning now to FIG. 3, the headbox 10 may include a dividing lamella 300 disposed within the headbox 10 between the first and second forming zones 50, 52. For instance, dividing lamella 300 may separate the first and second forming zones 50, 52 within headbox 10. Thus, e.g., dividing lamella 300 may restrict and / or prevent mixing of the foamed suspension of fibers in the first forming zone 50 with the foamed suspension of fibers in the second forming zone 52 within headbox 10. In example embodiments, dividing lamella 300 may be a wall that at least partially defines the first and second forming zones 50, 52. Thus, e.g., one side of dividing lamella 300 may face the first forming zone 50, and the opposite side of dividing lamella 300 may face the second forming zone 52. The headbox 10 may also include a second dividing lamella 400 disposed within the headbox 10 between the second and third forming zones 52, 54. For instance, the second dividing lamella 400 may separate the second and third forming zones 52, 54 within headbox 10. Thus, e.g . , the second dividing lamella 400 may restrict and / or prevent mixing of the foamed suspension of fibers in the second forming zone 52 with the foamed suspension of fibers in the third forming zone 54 within headbox 10. In example embodiments, the second dividing lamella 400 may be a wall that at least partially defines the second and third forming zones 52, 54. Thus, e.g., one side of the second dividing lamella 400 may face the second forming zone 52, and the opposite side of the second dividing lamella 400 may face the third forming zone 54. As noted above, headbox 10 may be a multi-layered incline foam-forming headbox. Thus, the second dividing lamella 400 may be positioned above the dividing lamella 300 along the vertical direction V in certain example embodiments. Second forming zone 52 may be positioned between dividing lamella 300 and the second dividing lamella 400 along the vertical direction V.

[0082] It will be understood that headbox 10 may include one, two, three, or more additional dividing lamellae for other forming zones within headbox 10. The illustrated arrangement is provided by way of example and is not intended to limit the present subject matter to a particular number of dividing lamellae.

[0083] The dividing lamella 300 may include an angled end 310 positioned at the forming surface 26. For instance, the angled end 310 of the dividing lamella 300 may be positioned adjacent the forming surface 26 such that a gap G is defined between the angled end 310 of the dividing lamella 300 and the forming surface 26. The angled end 310 of the dividing lamella 300 may be the end of dividing lamella 300 positioned closest forming surface 26, e.g., along a z-direction Z that is perpendicular to both a machine direction MD and a cross-machine direction, which is oriented into and out of the page in the view shown in FIG. 3.

[0084] The angled end 310 of the dividing lamella 300 may be oriented substantially parallel to the forming surface 26. For example, the angled end 310 of the dividing lamella 300 may be oriented to extend longitudinally along the machine direction MD with the forming surface 26 proximate the gap G between the angled end 310 of the dividing lamella 300 and the forming surface 26. As another example, with reference to FIG. 4, the forming surface 26 may be oriented at an angle p relative to a vertical direction V, e.g., within the headbox 10. The angle p may be no less than twenty degrees (20°) and no greater than forty degrees (40°). For instance, the angle p may be about thirty degrees (30°). Thus, headbox 10 may be a multi-layered incline foam-forming headbox, as shown in FIGS. 2 through 4. The angled end 310 of the dividing lamella 300 may also be oriented at the angle p relative to a vertical direction V. Moreover, in example embodiments, a first surface 312 of the angled end 310 (e.g., that faces towards the second formation zone 52) may also be oriented at the angle relative to a vertical direction V. Thus, the angled end 310 of the dividing lamella 300 may be oriented in the same or similar angle as the incline of the headbox 10.

[0085] As shown in FIG. 4, the angled end 310 of the dividing lamella 300 may have a length L, e.g., along the machine direction MD. The length L of the angled end 310 may be greater than the gap G. For instance, the length L of the angled end 310 may be greater than a height of the gap G, e.g., along the z-direction Z, between a second surface 314 of the angled end 310 (e.g., that faces towards the formation surface 26) and the forming surface 26. Such sizing of the gap G may advantageously allow a flow 250 of the first foamed suspension of fibers from the first forming zone 50 through the gap G into the second forming zone 52, as described in greater detail, to provide balanced fluid flow within the headbox 10 for uniform web formation. The second surface 314 of the angled end 310 may be positioned opposite the first surface 312 of the angled end 310 on dividing lamella 300. As noted above, the first surface 312 of the angled end 310 may face towards the forming surface 26. In certain example embodiments, the first and second surfaces 312, 314 of the angled end 310 may be disposed substantially parallel. For instance, in some example embodiments, dividing lamella 300 may be constructed of or with a piece of material, such as sheet metal, having a substantially uniform thickness, which may be bent to for the angled end 310 of the dividing lamella 300.

[0086] As shown in FIG. 3, the dividing lamella 300 may be positioned and oriented such that a cross-sectional area of the first forming zone 50, e.g., in a plane perpendicular to the machine direction MD and / or a horizontal direction, converges towards the angled end 310 of the dividing lamella 300, e.g., in the machine direction MD and / or a horizontal direction. By converging towards the angled end 310, the first forming zone 50 may be shaped such to facilitate control of the forming speed above the forming surface 26.

[0087] As shown in FIG. 4, the dividing lamella 300 may also include a panel 320. The panel 320 may extend longitudinally from angled end 310 of dividing lamella 300 to the opposite longitudinal end of the dividing lamella 300. The panel 320 may extend longitudinally at an angle with respect to the forming surface 26. For example, the panel 320 may be oriented at an angle of no less than twenty degrees (20°) and no greater than forty degrees (40°) relative to the forming surface 26. Thus, e.g., the panel 320 may be oriented generally perpendicular to the vertical direction V. The angled end 310 of the dividing lamella 300 may define an angle a with the panel 320 of the dividing lamella 300. The angle a may be no less than twenty degrees (20°) and no greater than forty degrees (40°). For instance, the angle a may be about thirty degrees (30°). A length L of the angled end 310 of the dividing lamella 300, e.g ., along the machine direction MD, may be less than a length of the panel 320 of the dividing lamella 300. For instance, in various example embodiments, the length L of the angled end 310 of the dividing lamella 300 may be less than half (1 / 2), no less than a quarter (1 / 4), or no less than an eighth (1 / 8) than the length of the panel 320 of the dividing lamella 300. In example embodiments, the length L of the angled end 310 of the dividing lamella 300 may be no less than twenty millimeters (20 mm) and no greater than one hundred millimeters (100 mm).

[0088] The angled end 310 of the dividing lamella 300 may be configured for directing a flow 252 of the second foamed suspension of fibers at the angled end 310 of the dividing lamella 300 substantially parallel to a flow 250 of the first foamed suspension of fibers from the first forming zone 50 through the gap G into the second forming zone 52. By directing the flow 252 of the second foamed suspension of fibers at the angled end 310 of the dividing lamella 300 substantially parallel to the flow 250 of the first foamed suspension of fibers from the first forming zone 50 through the gap G, the angled end 310 of the dividing lamella 300 may advantageously assist with reducing shear stress between the embryonic web 200 on the forming surface 26 and a layer forming on the embryonic web 200 from the foamed suspension of fibers in the second forming section 52.

[0089] During operation, a velocity of the second foamed suspension of fibers in the second forming section 52 may be greater than a velocity of the forming surface 26. Moreover, a velocity component of the flow of the second foamed suspension of fibers along the machine direction MD proximate the angled end 310 of the dividing lamella 300 may be greater than a velocity of the forming surface 26 along the machine direction MD. For example, the second foamed suspension of fibers in the second forming section 52 may include superabsorbent material, such as superabsorbent particles, and the flow rate of the second foamed suspension of fibers in the second forming section 52 may be selected to limit exposure time of the superabsorbent material to liquid, such as water, in the second foamed suspension of fibers. By directing the flow 252 of the second foamed suspension of fibers at the angled end 310 of the dividing lamella 300 substantially parallel to the flow 250 of the first foamed suspension of fibers from the first forming zone 50 through the gap G, direct impingement of the flow 252 of the second foamed suspension of fibers against the embryonic web 200 on the forming surface 26 may be reduced while maintaining the required flow rate for the second foamed suspension of fibers in the second forming section 52 to limit exposure time of the superabsorbent material to liquid. Without the angled end 310 of the dividing lamella 300, the flow 252 of the second foamed suspension of fibers could disadvantageously disrupt the embryonic web 200 on the forming surface 26 due to the direct impingement of the flow 252 of the second foamed suspension of fibers against the embryonic web The gap G between the forming surface 26 and the angled end 310 of the dividing lamella 300 may also be configured for a portion of the foamed suspension of fibers from the first forming section 50 to pass through the gap G into the second forming section 52. In the second forming section 52, the flow 250 of the foamed suspension of fibers from the first forming section 50 exiting the gap G may buffer the embryonic web 200 on the forming surface 26 from the flow 252 of the foamed suspension of fibers in the second forming section 52. Such buffering may dissipate shear forces due to speed and / or direction differences between the embryonic web 200 on the forming surface 26 and the layer forming on the embryonic web 200 from the foamed suspension of fibers in the second forming section 52.

[0090] The gap G may also be sized such a velocity of the foamed suspension of fibers from the first forming section 50 passing through the gap G into the second forming section 52 matches a velocity of the foamed suspension of fibers from the second forming section 52 at the angled end 310 of the dividing lamella 300. Such velocity matching may advantageously assist with enhancing layer purity of the embryonic web 200 on the forming surface 26 while the next layer is formed on the embryonic web 200 by the second foamed suspension of fibers in the second forming section 52. In addition, shear forces and mixing resulting from the speed difference between forming surface 26 and the second foamed suspension of fibers in the second forming section 52 may be contained within the flow 250 of the foamed suspension of fibers from the first forming section 50 entering the second forming section 52 through the gap G. In various example embodiments, the height of the gap G, e.g., along the z- direction Z, may be no less than five millimeters (5 mm) and no greater than fifty millimeters (50 mm), such as no less than ten millimeters (10 mm) and no greater than thirty millimeters (30 mm).

[0091] In contrast to the dividing lamella 300 described above, the second dividing lamella 400 may not include an angled end in some example embodiments. Rather, e.g., the second dividing lamella 400 may extend longitudinally at an angle with respect to the forming surface 26. For example, the second dividing lamella 400 may be oriented at an angle of no less than twenty degrees (20°) and no greater than forty degrees (40°) relative to the forming surface 26. Thus, e.g., the second dividing lamella 400 may be oriented generally perpendicular to the vertical direction V Because the second dividing lamella 400 does not include the angled end in FIG. 3, a flow of 254 of a third foamed suspension of fibers at the second dividing lamella 400 may impinge more directly against the embryonic web 200 on the forming surface 26 than in the manner described above for the dividing lamella 300. For instance, the flow 254 of the third foamed suspension of fibers at the second dividing lamella 400 may not be substantially parallel to the forming surface 26 but rather may be oriented an angle, such as no less than twenty degrees (20°) and no greater than forty degrees (40°), relative to the forming surface 26. However, a velocity of the flow of 254 of third foamed suspension of fibers may be less than the velocity of the flow of 252 of second foamed suspension of fibers. Moreover, the embryonic web 200 on the forming surface 26 may have sufficient wet strength to resist undesired deformation due to the flow of 254 of the third foamed suspension of fibers at the third formation section 54.

[0092] It will be understood that the second dividing lamella 400 may include an angled end in the manner described above for dividing lamella 300 in certain example embodiments. Moreover, other dividing lamellae in the headbox 10 may be configured in the same or similar manner to that described above for dividing lamella in 300 some example embodiments.

[0093] At least one vacuum box may be positioned opposite the headbox 10 about the forming surface 26 and be configured for drawing vacuum through the forming surface 26 to dewater the embryonic web 200 on the forming surface 26. For example, as shown in FIG. 4, the first and second drain devices 86 may be positioned opposite the first and second formation zones 50, 52, respectively, about the formation surface 26. The first and second drain devices 86 may be spaced from the gap G between the forming surface 26 and the angled end 310 of the dividing lamella 300, e.g., along the machine direction MD. Thus, the vacuum through the forming surface 26 at the angled end 310 of the dividing lamella 300 may be reduced relative to adjacent portions of the forming surface 26, e.g., at the first and second formation zones 50, 52. As another example, openings of the first and second drain devices 86 may be positioned relative to the angled end 310 of the dividing lamella 300 such that the vacuum through the forming surface 26 at the angled end 310 of the dividing lamella 300 may be reduced relative to adjacent portions of the forming surface 26, e.g., at the first and second formation zones 50, 52. For instance, openings of the first and second drain devices 86 at the gap G may be plugged or omitted to reduce the vacuum at the gap G.

[0094] As shown in FIG. 5, in some example embodiments, the dividing lamella 300 may be adjustable in order to change a size of the gap G between the angled end 310 of the dividing lamella 300 and the forming surface 26, e.g., along the z-direction Z. Changing the size of the gap G may allow varying a speed of the flow 250 of the first foamed suspension of fibers from the first forming zone 50 through the gap G into the second forming zone 52, which can advantageously allow for enhanced uniformity.

[0095] FIG. 6 illustrates a method 500 for foam forming according to an example embodiment of the present subject matter. As an example, method 500 may be used in or with system 10 (FIGS. 1 through 5) to foam forming uniform nonwoven webs with reduced defects relative to convention methods. While method 500 is described in greater detail below in the context of system 10, it will be understood that method 500 may be used in or within any suitable system or process in alternative example embodiments.

[0096] At 510, the method includes flowing a first foamed suspension of fibers into a first forming zone of a headbox. For instance, first pumping device 68 may pump the first foamed suspension of fibers into the first forming zone 50. The first foamed suspension of fibers into the first forming zone 50 may be essentially free of superabsorbent material in some example embodiments. At 520, the method includes flowing a second foamed suspension of fibers into a second forming zone of a headbox. For instance, second pumping device 70 may pump the second foamed suspension of fibers into the second forming zone 52. The second foamed suspension of fibers into the second forming zone 52 may include superabsorbent material in some example embodiments.

[0097] At 530, the method includes depositing the first foamed suspension of fibers onto the forming surface while the forming surface is moving in order to form an embryonic web. For example, the first forming zone 50 may deposit the first foamed suspension of fibers directly onto the forming surface 26 in order to form the embryonic web 200 on the moving forming surface 26. It will be understood that, while the first pumping device 68 pumps the first foamed suspension of fibers into the first forming zone 50 at 510, the first forming zone 50 may deposit the first foamed suspension of fibers directly onto the forming surface 26 at 530.

[0098] At 540, the method includes depositing the second foamed suspension of fibers onto the forming surface while the forming surface is moving in order to form another layer on the embryonic web. For example, the second forming zone 52 may deposit the second foamed suspension of fibers directly onto the embryonic web 200 on the moving forming surface 26. It will be understood that, while the second pumping device 70 pumps the second foamed suspension of fibers into the second forming zone 50 at 520, the second forming zone 52 may deposit the second foamed suspension of fibers directly onto the embryonic web 200 on the moving forming surface 26 at 540.

[0099] During 540, an angled end of a dividing lamella directs a flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella substantially parallel to the forming surface. For example, the angled end 310 of the dividing lamella 300 may direct the flow 252 of the second foamed suspension of fibers at the angled end 310 of the dividing lamella 300 substantially parallel to the forming surfaced 26 and / or the flow 250 of the first foamed suspension of fibers from the first forming zone 50 through the gap G into the second forming zone 52. By directing the flow of the second foamed suspension of fibers proximate the angled end 310 of the dividing lamella 300 substantially parallel to the forming surface 26, the angled end 310 of the dividing lamella 300 may advantageously assist with reducing the shear stress between the embryonic web 200 on the forming surface 26 and the layer forming on the embryonic web 200 from the foamed suspension of fibers in the second forming section 52. Such arrangement of the angled end 310 of the dividing lamella 300 may also advantageously provide increased weight uniformity along a cross-machine direction.

[0100] During 540, a portion of foamed suspension of fibers in the first forming section may also flow between the forming surface and the dividing lamella towards the second forming section, e.g., rather than being drained through the forming surface for the embryonic web. In the second forming section 52, the foamed suspension of fibers from the first forming section 50 that passes between the forming surface 26 and the dividing lamella 300 may act as a buffer for the embryonic web 200 against the flow 252 of the foamed suspension of fibers in the second forming section 52. Advantageously, such buffer may dissipate shear forces due to speed and / or direction differences between the embryonic web 200 and the layer forming on the embryonic web 200 from the foamed suspension of fibers in the second forming section 52. During 540, a velocity of the foamed suspension of fibers from the first forming section passing through the gap into the second forming section may match a velocity of the foamed suspension of fibers from the second forming section at the angled end of the dividing lamella. Such velocity matching may advantageously assist with enhancing layer purity.

[0101] At 540, a velocity of the second foamed suspension of fibers in the second forming section may be greater than a velocity of the forming surface. For example, a velocity component of the flow 252 of the second foamed suspension of fibers along the machine direction MD proximate the angled end 310 of the dividing lamella 300 may be greater than a velocity of the forming surface 26 along the machine direction MD. In some example embodiments, the velocity component of the flow 252 of the second foamed suspension of fibers along the machine direction MD proximate the angled end 310 of the dividing lamella 300 may be no less than four times (4X), no less than five times (5X), no less than six times (6X), no less than seven times (7X), no less than eight times (8X), etc. greater than the velocity of the forming surface 26 along the machine direction MD. The greater the velocity differential between the flow 252 of the second foamed suspension of fibers along the machine direction MD proximate the angled end 310 of the dividing lamella 300 relative to the velocity of the forming surface 26 along the machine direction MD, the greater the potential shear stress applied to the embryonic web 200 on the formation surface 26. The angled end of the dividing lamella and tight control over supply and drainage flows in the headbox 10 may advantageously assist with managing shears stresses during web formation and avoid defects due to such shear stresses.

[0102] At 540, dewatering of the embryonic web may also be limited at the gap between the forming surface and the bottom surface of the angled end facing the forming surface. For instance, the vacuum through the forming surface 26 at the angled end 310 of the dividing lamella 300 may be reduced relative to adjacent portions of the forming surface 26, e.g., at the first and second formation zones 50, 52. Limiting vacuum dewatering proximate the angled end facing the forming surface may advantages assist with limiting or preventing exposure of superabsorbent material to the forming surface, which can allow the superabsorbent material to pass through the forming surface and / or fall out of the embryonic web in various parts of the manufacturing and subsequent processing.

[0103] FIG. 6 depicts steps performed in a particular order for purposes of illustration and discussion. Those of ordinary skill in the art, using the disclosures provided herein, will understand that the steps of any of the methods discussed herein may be adapted, rearranged, expanded, omitted, or modified in various ways without deviating from the scope of the present disclosure.

[0104] TEST METHODS

[0105] Laver Relative Thickness Test Method

[0106] The Layer Relative Thickness Test Method is used to determine a particular layer thickness of a z-directional layer of a sample including two or more z-directional layers. For each sample substrate, seven cross-sectional images are taken. Each cross-sectional sample is imaged with conventional microCT equipment, such as Bruker Skyscan 1272, to provide an image. The width of each sample for cross-sectional imaging is about 7mm. The Micro-CT conditions used to scan and reconstruct the samples may be set as follows: Source Voltage (kV) = 30; Source Current (uA) = 150; Image Pixel Size (urn) = 7.0; Frame Averaging=ON (6); and Random Movement=ON (10).

[0107] Imaged software should be downloaded (such as from the National Institute of Health (NIH) - https: / / imagej.nih.gov / ij / ) on to a computer. The image analysis algorithm is used to measure layer thickness from microCT cross-sectional slices. Every 50thimage is analyzed between numbers 1 ,000 and 1 ,900 to collect nineteen images per sample. The nineteen images for each sample are loaded into the Imaged software, converted to grayscale, and rotated ninety degrees, such that the interface between separate layers is oriented in a generally vertical fashion. The image is made grayscale using the Make Binary function in Imaged. Auto BC is set on the image to normalize the images and the grayscale for the light fibers in one layer should be set to be the same as the light fibers in the other images, and likewise for the dark fibers (or particles) of a different layer with dark fibers (or particles) of that layer in the other images.

[0108] The layer thickness is measured by measuring the width of the layer where SAM particles are present using the grayscale plot from the plot profile function and setting an appropriate threshold to distinguish the region such as the mid-point of grayscale between the pure fiber region and the pure SAM region. The total thickness for a sample is the width of the area selected for the plot profile function. For purposes herein, a layer relative thickness for an image of a substrate is the measured layer thickness divided by the total thickness for that image. For purposes herein, a layer relative thickness percentage of the total thickness of a substrate is calculated by averaging the layer relative thickness for the seven images.

[0109] EXAMPLES

[0110] Laver Damage

[0111] The effect of a dividing lamella with an angled end, also referred to as a “kinked lamella”, on a three-layer nonwoven web was evaluated, including damage to an underlying layer during formation and layer purity of a layer formed with the kinked lamella. The three-layer nonwoven webs formed with the kinked lamella were evaluated relative to three-layer nonwoven webs formed with a dividing lamella without an angled end, also referred to as a “flat lamella”. The kinked lamella, namely the angled end, was oriented at three degrees (3°) relative to the forming surface. The flat lamella, namely the corresponding end, was oriented at thirty degrees (30°) relative to the forming surface.

[0112] The same fiber furnish was used for all nonwoven webs formed with the kinked lamella and the flat lamella. Various properties of the formation process used to form the three-layer nonwoven webs with the kinked lamella and the flat lamella are listed below in Table 1 . Inventive Sample 11 , 12 were formed with the kinked lamella, and Comparative Samples C1 , C2, C3 were formed with the flat lamella.

[0113] Each of the three-layer nonwoven webs included a middle layer with SAM particles and a first layer on which middle layer is deposited during the foam forming process for the three-layer nonwoven webs. Without wishing to be bound to any particular theory, it is believed that the kinked lamella redirects the foamed suspension of fibers and SAM particles used to form the middle layer generally parallel to the forming surface and the first layer thereon while the flat lamella allows the foamed suspension of fibers and SAM particles used to form the middle layer to impinge against and damage the first layer on the forming surface during the foam forming process.

[0114] Thicknesses ranges (90% confidence) of the middle layers and the first layer for the Inventive Sample 11 , 12 and Comparative Samples C1 , C2, C3 are listed below in Table 2.

[0115] As may be seen from the above, the first layer is significantly thinner when formed using the flat lamella relative to the kinked lamella. Thus, the kinked lamella can reduce damage to the first layer during the foam forming process by redirecting the foamed suspension of fibers and SAM particles generally parallel to the forming surface and the first layer thereon. In addition, it can also be seen that the kinked lamella allows for significantly increased jet:wire ratios to be utilized without significant damage to the first layer. In contrast, the flat lamella may only be used with relatively small jet:wire ratios to avoid damaging the first layer. The operating window for the foam forming process can thus be larger when using the kinked lamella relative to the flat lamella.

[0116] In general, forming angle can have a significant impact on layer purity between the first and middle layers. This is shown by the significant amount of SAM particles pulling through the first layer when the flat lamella is used relative to the kinked lamella at the same jet:wire speed ratios In addition, a lower forming angle can allow for a higher jet:wire speed ratio range without damaging the first layer. Using the flat lamella required going as low as 2.4 for the jet:wire ratio before layer purity looked similar to (but still worse than) using a 17 jet:wire ratio with the kinked lamella.

[0117] CD Basis Weight

[0118] The effect of a kinked lamella on the cross direction basis weight profile of three-layer nonwoven webs was also evaluated. Without wishing to be bound by any particular theory, it is believed that increasing a nose to wire gap, e.g., independently of a lamella to nose gap will improve the cross direction basis weight variability because there is more space for the low basis weight areas to fill-in during the foam forming process. The same fiber furnish was used for all nonwoven webs formed with the kinked lamella.

[0119] Various properties of the formation process used to form three-layer nonwoven webs with the kinked lamella are listed below in Table 3.

[0120] The "Lamella to Wire Gap” corresponds to a spacing between the angled end of the kinked lamella and the forming surface along the z-direction. The "Nose to Wire Gap” corresponds to a spacing between a flow-spreader nose of the headbox and the forming surface along the z-direction. The "Lamella to Nose Gap” corresponds to a spacing between the angled end of the kinked lamella and the flow-spreader nose of the headbox along the z-direction.

[0121] Samples X3, X4, and X6 held the Nose to Wire Gap constant at ten millimeters (10 mm) and moved the kinked lamella to different distances from the forming surface to create three different Lamella to Nose Gaps (and Lamella to Wire Gaps). The cross direction basis weight variability decreased as the Jet: Wire ratio increased (by decreasing the Lamella to Nose Gap). Moreover, increasing the Jet:Wire ratio from 5.5 to about 7.5 resulted in an 18.7% decrease in the cross direction basis weight variability. This trend was also created using the eight millimeter (8 mm) Nose to Wire Gap of Samples X2, X5 but the trend was flatter. These results indicate that to reduce the cross direction basis weight variability, bringing the kinked lamella closer to the nose piece to increase Jet:Wire ratio is advantageous.

[0122] Samples X1 , X5 show the effect of the Nose to Wire Gap on cross direction basis weight variability when separated from the Lamella to Nose Gap / Jet:Wire ratio. The cross direction basis weight variability decreased with as the Nose to Wire Gap increased. Increasing the Nose to Wire Gap from six millimeters (6 mm) in Sample X1 to eight millimeters (8 mm) in Sample X5 yielded a 15% decrease in cross direction basis weight variability. Thus, cross direction basis weight variability decreases as the nose to wire gap increases. Distance from the nose to the wire also has an impact on cross direction basis weight variability both when adjusted with the lamella to nose gap and when adjusted independently.

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

[0124] EXAMPLE EMBODIMENTS

[0125] First example embodiment: A system for producing webs, comprising: a forming surface; a headbox positioned adjacent the forming surface, the headbox comprising a first forming zone and a second forming zone, the first forming zone configured for directing a first foamed suspension of fibers onto the forming surface, the second forming zone configured for directing a second foamed suspension of fibers onto the forming surface; and a dividing lamella disposed within the headbox between the first and second forming zones, the dividing lamella comprising an angled end positioned at the forming surface, the angled end of the dividing lamella oriented substantially parallel to the forming surface.

[0126] Second example embodiment: The system of the first example embodiment, further comprising at least one vacuum box positioned opposite the headbox about the forming surface, the at least one vacuum box configured for drawing vacuum through the forming surface to dewater an embryonic web on the forming surface, wherein the at least one vacuum box comprises a plurality of openings for drawing the vacuum through the forming surface, the plurality of openings positioned relative to the angled end of the dividing lamella such that the vacuum through the forming surface at the angled end of the dividing lamella is reduced relative to adjacent portions of the forming surface.

[0127] Third example embodiment: The system of the first example embodiment or the second example embodiment, wherein a length of the angled end of the dividing lamella along a machine direction is greater than a gap between the angled end of the dividing lamella and the forming surface.

[0128] Fourth example embodiment: The system of any one of the first through third example embodiments, wherein the angled end of the dividing lamella is configured for directing a flow of the second foamed suspension of fibers at the angled end of the dividing lamella substantially parallel to a flow of first foamed suspension of fibers through a gap between the angled end of the dividing lamella and the forming surface into the second forming zone.

[0129] Fifth example embodiment: The system of any one of the first through the fourth example embodiments, wherein the dividing lamella is adjustable in order to change a size of a gap between the angled end of the dividing lamella and the forming surface.

[0130] Sixth example embodiment: The system of any one of the first through the fifth example embodiments, wherein the dividing lamella is positioned and oriented such that a cross-sectional area of the first forming zone in a plane perpendicular to a machine direction converges towards the angled end of the dividing lamella in the machine direction. Seventh example embodiment: The system of any one of the first through sixth example embodiments, wherein the angled end of the dividing lamella defines an angle with a panel of the dividing lamella, the angle being no less than twenty degrees and no greater than forty degrees.

[0131] Eighth example embodiment: The system of any one of the first through seventh example embodiments, wherein a length of the angled end of the dividing lamella is less than a length of the panel of the dividing lamella.

[0132] Nineth example embodiment: The system of any one of the first through eighth example embodiments, wherein: a first surface of the angled end faces towards the forming surface; a second surface of the angled end is positioned opposite the first surface of the angled end and faces towards the second forming zone; and the first and second surfaces of the angled end are disposed substantially parallel.

[0133] Tenth example embodiment: The system of any one of the first through nineth example embodiments, wherein the forming surface is oriented at an angle relative to a vertical direction, the angle being no less than twenty degrees and no greater than forty degrees.

[0134] Eleventh example embodiment: A method for producing webs, comprising: flowing a first foamed suspension of fibers into a first forming zone of a headbox; flowing a second foamed suspension of fibers into a second forming zone of a headbox, the second forming zone separated from the first forming zone within the headbox by a dividing lamella, the dividing lamella comprising an angled end positioned at a forming surface, the angled end of the dividing lamella oriented substantially parallel to the forming surface; depositing the first foamed suspension of fibers onto the forming surface while the forming surface is moving in order to form an embryonic web; and depositing the second foamed suspension of fibers onto the embryonic web while the forming surface is moving in order to form another layer on the embryonic web, the angled end of the dividing lamella directing a flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella substantially parallel to the forming surface.

[0135] Twelfth example embodiment: The method of the eleventh example embodiment, wherein a machine direction velocity component of the flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella is greater than a machine direction velocity of the forming surface.

[0136] Thirteenth example embodiment: The method of either the eleventh or the twelfth example embodiments, wherein the machine direction velocity component of the flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella is no less than four times greater than the machine direction velocity of the forming surface. Fourteenth example embodiment: The method of any one of the eleventh though thirteenth example embodiments, wherein first foamed suspension of fibers is essentially free of superabsorbent material, and the second foamed suspension of fibers comprises superabsorbent material.

[0137] Fifteenth example embodiment: The method of any one of the eleventh through fourteenth example embodiments, further comprising drawing vacuum through the forming surface to dewater the embryonic web on the forming surface, wherein the vacuum through the forming surface is reduced proximate the angled end of the dividing lamella relative to adjacent portions of the forming surface.

[0138] Sixteenth example embodiment: The method of any one of the eleventh through fifteenth example embodiments, wherein a length of the angled end of the dividing lamella along a machine direction is greater than a gap between the angled end of the dividing lamella and the forming surface.

[0139] Seventeenth example embodiment: The method of any one of the eleventh through sixteenth example embodiments, wherein depositing the first foamed suspension of fibers onto the forming surface comprises flowing a portion of the first foamed suspension of fibers through a gap between the angled end of the dividing lamella and the forming surface towards the second forming zone in order to buffer the embryonic web from a flow of the second foamed suspension of fibers at the angled end of the dividing lamella.

[0140] Eighteenth example embodiment: The method of any one of the eleventh through seventeenth example embodiments, further comprising adjusting the dividing lamella in order to change a size of a gap between the angled end of the dividing lamella and the forming surface.

[0141] Nineteenth example embodiment: The method of any one of the eleventh through eighteenth example embodiments, wherein the dividing lamella is positioned and oriented such that a cross- sectional area of the first forming zone in a plane perpendicular to a machine direction converges towards the angled end of the dividing lamella in the machine direction.

[0142] Twentieth example embodiment: The method of any one of the eleventh through nineteenth example embodiments, wherein: a first surface of the angled end faces towards the forming surface; a second surface of the angled end is positioned opposite the first surface of the angled end and faces towards the second forming zone; and the first and second surfaces of the angled end are disposed substantially parallel.

[0143] Twenty-first example embodiment: The method of any one of the eleventh through twentieth example embodiments, wherein the forming surface is oriented at an angle relative to a vertical direction, the angle being no less than twenty degrees and no greater than forty degrees.

[0144] Twenty-second example embodiment: The method of any one of the eleventh through twenty- first example embodiments, further comprising drying the embryonic web.

Claims

What Is Claimed:1 . A system for producing webs, comprising: a forming surface; a headbox positioned adjacent the forming surface, the headbox comprising a first forming zone and a second forming zone, the first forming zone configured for directing a first foamed suspension of fibers onto the forming surface, the second forming zone configured for directing a second foamed suspension of fibers onto the forming surface; and a dividing lamella disposed within the headbox between the first and second forming zones, the dividing lamella comprising an angled end positioned at the forming surface, the angled end of the dividing lamella oriented substantially parallel to the forming surface.

2. The system of claim 1 , further comprising at least one vacuum box positioned opposite the headbox about the forming surface, the at least one vacuum box configured for drawing vacuum through the forming surface to dewater an embryonic web on the forming surface, wherein the at least one vacuum box comprises a plurality of openings for drawing the vacuum through the forming surface, the plurality of openings positioned relative to the angled end of the dividing lamella such that the vacuum through the forming surface at the angled end of the dividing lamella is reduced relative to adjacent portions of the forming surface.

3. The system of claim 1 , wherein a length of the angled end of the dividing lamella along a machine direction is greater than a gap between the angled end of the dividing lamella and the forming surface.

4. The system of claim 1 , wherein the angled end of the dividing lamella is configured for directing a flow of the second foamed suspension of fibers at the angled end of the dividing lamella substantially parallel to a flow of first foamed suspension of fibers through a gap between the angled end of the dividing lamella and the forming surface into the second forming zone.

5. The system of claim 1 , wherein the dividing lamella is adjustable in order to change a size of a gap between the angled end of the dividing lamella and the forming surface.

6. The system of claim 1 , wherein the dividing lamella is positioned and oriented such that a cross-sectional area of the first forming zone in a plane perpendicular to a machine direction converges towards the angled end of the dividing lamella in the machine direction.

7. The system of claim 1 , wherein the angled end of the dividing lamella defines an angle with a panel of the dividing lamella, the angle being no less than twenty degrees and no greater than forty degrees.

8. The system of claim 7, wherein a length of the angled end of the dividing lamella is less than a length of the panel of the dividing lamella.

9. The system of claim 1 , wherein: a first surface of the angled end faces towards the forming surface; a second surface of the angled end is positioned opposite the first surface of the angled end and faces towards the second forming zone; and the first and second surfaces of the angled end are disposed substantially parallel.

10. The system of claim 1 , wherein the forming surface is oriented at an angle relative to a vertical direction, the angle being no less than twenty degrees and no greater than forty degrees.

11. A method for producing webs, comprising: flowing a first foamed suspension of fibers into a first forming zone of a headbox; flowing a second foamed suspension of fibers into a second forming zone of a headbox, the second forming zone separated from the first forming zone within the headbox by a dividing lamella, the dividing lamella comprising an angled end positioned at a forming surface, the angled end of the dividing lamella oriented substantially parallel to the forming surface; depositing the first foamed suspension of fibers onto the forming surface while the forming surface is moving in order to form an embryonic web; and depositing the second foamed suspension of fibers onto the embryonic web while the forming surface is moving in order to form another layer on the embryonic web, the angled end of the dividing lamella directing a flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella substantially parallel to the forming surface.

12. The method of claim 11 , wherein a machine direction velocity component of the flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella is greater than a machine direction velocity of the forming surface.

13. The method of claim 12, wherein the machine direction velocity component of the flow of the second foamed suspension of fibers proximate the angled end of the dividing lamella is no less than four times greater than the machine direction velocity of the forming surface.

14. The method of claim 12, wherein first foamed suspension of fibers is essentially free of superabsorbent material, and the second foamed suspension of fibers comprises superabsorbent material.

15. The method of claim 11 , further comprising drawing vacuum through the forming surface to dewater the embryonic web on the forming surface, wherein the vacuum through the forming surface is reduced proximate the angled end of the dividing lamella relative to adjacent portions of the forming surface.

16. The method of claim 11 , wherein a length of the angled end of the dividing lamella along a machine direction is greater than a gap between the angled end of the dividing lamella and the forming surface.

17. The method of claim 11 , wherein depositing the first foamed suspension of fibers onto the forming surface comprises flowing a portion of the first foamed suspension of fibers through a gap between the angled end of the dividing lamella and the forming surface towards the second forming zone in order to buffer the embryonic web from a flow of the second foamed suspension of fibers at the angled end of the dividing lamella.

18. The method of claim 11 , further comprising adjusting the dividing lamella in order to change a size of a gap between the angled end of the dividing lamella and the forming surface.

19. The method of claim 11 , wherein the dividing lamella is positioned and oriented such that a cross-sectional area of the first forming zone in a plane perpendicular to a machine direction converges towards the angled end of the dividing lamella in the machine direction.

20. The method of claim 11 , wherein: a first surface of the angled end faces towards the forming surface; a second surface of the angled end is positioned opposite the first surface of the angled end and faces towards the second forming zone; andthe first and second surfaces of the angled end are disposed substantially parallel.21 . The method of claim 11 , wherein the forming surface is oriented at an angle relative to a vertical direction, the angle being no less than twenty degrees and no greater than forty degrees.

22. The method of claim 11 , further comprising drying the embryonic web.

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