Method and machine for producing a dried fibrous web

Abstract

The invention relates to a method and a machine for producing a fibrous web (309), preferably a tissue, paper or cardboard web or a nonwoven web, in particular a tissue web with a basis weight of 28 g / m² 2 up to 42 g / m² 2, with a low-water raw material processing of cellulose-containing fibers, preferably virgin fiber pulp in bales and / or recycled fibers, to individual fibers and / or fiber bundles; wherein the individual fibers and / or fiber bundles are formed in an air stream into a fiber fabric (300) on a, preferably permeable, support element (40) by a dry forming process in a fiber fabric width (BF1, BF2); and wherein a first application of an agent, in particular a liquid and / or vaporous and / or powdery agent, preferably water and / or a water-additive mixture and / or a powder and / or water vapor, is carried out on the fiber fabric, preferably over the entire surface; and wherein the fiber fabric is consolidated, preferably over the entire surface;and wherein a final application of agent, in particular a liquid and / or vaporous and / or powdery agent, preferably a water-additive mixture and / or a powder and / or a water-additive vapor, is carried out by means of a final application device (72, 73) onto the solidified fiber fabric, preferably over the entire surface, in an application width (BA). The invention is characterized in that the application width (BA) in the final application step e) is set to be less than or equal to the fiber fabric width (BF1, BF2) and that, after the final application step e), the solidified fiber fabric is cut into two edge strips (105) and the fiber web (309) by means of a first double-sided edge trimming f) in the transverse direction (CD) by means of a double-sided edge cutting device (51) such that the two edge strips (105) each have an area (107) applied with agent and each have an area (108) free of agent.

Description

[0001] The invention relates to a method for producing a fibrous web, preferably a tissue, paper or cardboard web or a nonwoven web, in particular a tissue web with a basis weight of 28 g / m². 2 up to 42 g / m² 2 , comprising the following steps: a) low-water or dry raw material processing of cellulose-containing fibers, preferably virgin fiber pulp as bales and / or recycled fibers, into individual fibers and / or fiber bundles using a raw material processing plant; b) Forming the individual fibers and / or fiber bundles in the airflow to form a planar fiber fabric with a fiber fabric width in the transverse direction on a, preferably permeable, support element by means of a dry forming process using a dry forming device; c) first application of a strength-enhancing agent, in particular a liquid and / or vaporous and / or powdery agent, preferably water and / or a water-additive mixture and / or a powder and / or a water vapor and / or a water vapor-additive mixture, to the fiber fabric by means of a first application device; d) Consolidation of the planar fiber fabric by applying pressure, preferably over the entire surface, in a consolidation gap, to form a consolidated fiber fabric, by means of a final consolidation device; e) a final, preferably full-surface, application of a strength-enhancing agent, in particular a liquid and / or vaporous and / or powdery agent, preferably a water-additive mixture and / or a powder and / or a water vapor-additive mixture, in an application width in the transverse direction by means of a final application device onto the solidified fiber fabric having a fiber fabric width, wherein the final application step e) is carried out after a final solidification step d);

[0002] The invention also relates to a machine for the production of a fibrous web.

[0003] Many fibrous webs, and especially paper, cardboard, and tissue webs, were and still are produced almost exclusively using the wet process on an industrial scale. For this process, unless recycled paper is used, baled pulp is typically dissolved in large quantities of water in a vat, resulting in a fiber suspension consisting of approximately 99% water and only about 1% fibers by weight. This fiber suspension is then applied to a forming wire via a headbox to form sheets. The resulting fibrous web is subsequently dewatered or dried by pressure and heat until it can be wound up or otherwise processed. The wet process has the advantage that hydrogen bonds form between the individual fibers during dewatering or drying, giving the fibrous web the necessary strength.However, a disadvantage of this process is that drying the fiber web requires large amounts of energy. Especially in light of current climate change, there is therefore an intensive search for alternatives to this traditional wet process.

[0004] As an alternative to the wet process, the dry air lay-up process is already known, in which fibers are laid down to form a fiber web in a largely dry state. To give the fiber web the necessary strength, only relatively small amounts of water (for the formation of hydrogen bonds) and / or other binders are added. This results in significantly less energy being required for drying. One challenge with this process is achieving good and uniform fiber distribution (also called formation). Unlike in suspension, dry fibers tend to form undesirable clumps. Therefore, precise fiber separation is extremely important. For this reason, so-called "fluff pulp" is generally used for the dry air lay-up process.This refers to pulp that has been pre-treated so that the individual fibers already have fewer and / or weaker bonds to each other. This makes the pulp more voluminous, more absorbent, and better suited for the dry air layup process. However, fluff pulp, which is usually produced in rolls, is much more expensive than ordinary baled pulp, as is typically used in the paper industry. Therefore, the dry air layup process is currently used primarily only for the production of sanitary products, such as diapers, and not for the production of paper, cardboard, or tissue webs, at least not on an industrial scale. For such an industrial level, the use of fluff pulp would be uneconomical, despite currently high energy costs.

[0005] Document WO 2019 / 137 667 A1 discloses a method and a device for producing a fiber mat from fibrous recycled material using a low-water processing and dry forming process. After the dry forming of the fibers, at least one moistening device is provided, which applies water to the fiber mat. This at least one moistening device is arranged upstream or within a subsequent consolidation device to improve the consolidation of the fiber mat.

[0006] For example, a drying process and a device for tissue webs using virgin fiber pulp in roll form ("fluff pulp") with direct feeding to a fiberizing device are described in German patent DE 1 965 716 A1. The described drying process discloses the application of water and / or the application of wet-strength agents prior to the consolidation of the tissue web to increase its strength. Optionally, a further application of starch or adhesives to prevent linting can be provided before or after consolidation of the tissue web. The application can be carried out by spraying and / or, preferably in the case of wet-strength agents, by means of a combined roller applicator. Furthermore, the wet-strength agents are preferably applied only to the consolidated areas and not to the unconsolidated areas of the tissue web.

[0007] A disadvantage has been found to be that the produced fiber web either cannot be continuously coated with agent across its entire transverse direction or width, or that continuous coating leads to contamination problems of the support elements, such as the circulating belts or rollers used, resulting in undesirable production downtimes or increased cleaning costs.

[0008] The object of the invention is to provide a method and a device for the low-water or dry production of a fibrous web, in particular a tissue web, on an industrial level with an application of a strength-enhancing agent, in particular a liquid and / or vaporous and / or powdery agent, preferably water and / or a water-additive mixture and / or a powder and / or water vapor, with reduced soiling or contamination of the components by the agent used.

[0009] "At an industrial level" means that a high, continuous production speed of 150 m / min or greater, in particular 250 m / min or greater, preferably 400 m / min or greater, and a width of the continuously produced fibrous web of 0.5 m or greater, preferably 1 m or greater, in particular 2.3 m or greater, up to 10 m or less, is required.

[0010] The fiber web should exhibit high mechanical strength and high quality in both dry and wet states. High mechanical strength can be determined, for example, by tear resistance or tensile strength in the machine direction (MD) and cross direction (CD). Quality can be determined, for example, by uniform fiber formation or a consistent basis weight profile in MD and / or CD. Other quality parameters of a manufactured tissue web include its feel (touch), appearance, and absorption rates. For example, end consumers expect high absorbency, a good appearance, and a pleasant feel from manufactured wipes intended for household use.

[0011] To distinguish between the manufactured fiber webs, for example a tissue, paper or cardboard web or a non-woven web, the following distinction is made, which is based on fiber length, density and fiber bonding type.

[0012] A tissue, paper, or cardboard web is defined as a fibrous web with predominantly medium fiber lengths, preferably shorter fiber lengths compared to a nonwoven web, of 5 mm or less, particularly 4 mm or less, and preferably 3 mm or less. Furthermore, the fibers are predominantly bonded by hydrogen bonds (OH bonds), and the fiber density is greater than or equal to 0.4 g / cm³. 3 understood.

[0013] The fibers used in a tissue, paper or cardboard web are additionally characterized by having a slenderness ratio of fiber length to fiber diameter of less than or equal to 200, in particular less than or equal to 150, preferably less than or equal to 100.

[0014] A nonwoven web, which also consists primarily of fibers, is defined, as a key distinction from tissue, paper, or cardboard webs, by having a fiber content of between 30% and 52% of very long fibers with an average fiber length of more than 5 mm, or continuous fibers, which determine the nonwoven characteristics. Furthermore, a fiber-to-diameter ratio of greater than or equal to 300 is targeted for a nonwoven web.

[0015] The remaining fiber content of a nonwoven fabric web can have a different composition, and the bulk density of the remaining fiber content should be below 0.4 g / cm³. 3to classify them as nonwovens.

[0016] Another distinguishing feature between a nonwoven web and a tissue, paper, or cardboard web lies in the way the fibers are bonded to one another. In nonwovens, the fibers are bonded by interlocking (through entanglement, for example, "spun-lacing" or "hydro-entangling") and / or by cohesion and / or adhesion. However, it is also common for nonwoven webs produced using the wet-forming process, which is similar to papermaking, to be referred to sometimes as nonwovens and other times as long-fiber specialty paper webs.

[0017] Under a structured and / or reinforced fibrous web, in particular a tissue web with a basis weight of 28 g / m² 2 up to 42 g / m² 2In the context of a tissue web, preferably with at least one low-pressure and at least one high-pressure zone, it is understood that the fiber web maintains a constant basis weight distribution in the machine direction (MD) and cross direction (CD). This differs from an embossing or commonly used structuring process. Such a process is commonly known in tissue web production under the English term "embossing." In this commonly used process, the fibers are "bent" into the desired structure, and the previously formed fiber layup with its existing fiber bonds is partially broken up. This breaking up occurs because the fibers within the layup are pulled apart by the bending process. This pulling apart results in different basis weights across the fiber web in the MD and / or CD directions.

[0018] In the structuring and / or consolidation process described in the invention, the fiber fabric is consolidated without any fiber elongation relative to each other. This results in a substantially constant basis weight distribution of the fiber fabric or fiber web in MD and / or CD. Furthermore, the fiber web is consolidated across its entire length and width, preferably with at least one low-pressure layer.

[0019] For example, a tissue web with at least one low-pressure and one high-pressure zone is consolidated, compressed, pressed or structured over its entire width and length or surface; this means that the low-pressure and high-pressure zones are consolidated in different proportions to each other, with the low-pressure zone having a lower degree of consolidation than the high-pressure zones.

[0020] The problem described above is solved by the features of the independent claims. The dependent claims relate to advantageous embodiments of the present invention.

[0021] According to the invention, a method for producing a fibrous web is proposed, which is characterized in that the application width in the last application step e) is set to be less than or equal to the fiber layup width, and that after the last application step e) the consolidated fiber layup is cut into two edge strips and the fibrous web by means of a first double-sided edge trimming f) in the transverse direction using a double-sided edge cutting device, such that the two edge strips each have an area applied with strength-enhancing agent, in particular a liquid and / or vaporous and / or powdery strength-enhancing agent, preferably a water-additive mixture and / or a powder and / or a water-additive vapor, and each have an agent-free area.

[0022] The inventors have recognized that by carrying out the last application step e) after a last consolidation step d), contamination of the pressing and / or support elements used in consolidation step d) by the strength-enhancing agent, preferably the water-additive mixture, can be largely avoided.

[0023] Furthermore, it is advantageous to adjust the application width in application step e) such that the application of agent, preferably a water-additive mixture, takes place only within the fiber layup edges in the transverse direction of the solidified fiber layup, this enables a further reduction of the contamination of the support elements used, for example the sieves, belts or rollers in the area of ​​application.

[0024] Furthermore, it is advantageous to carry out a double-sided edge trimming of the consolidated fiber lay-up before the rolling and after the last application step e), wherein the edge trimming is carried out in such a way that the two cut-off edge strips are chosen to be wide enough to cut off the center-free outer area of ​​the edge strip and a center-applied area of ​​the edge strip in the transverse direction that is kept as small as possible.

[0025] In an alternative embodiment, the method is characterized in that the last application step e) and / or the first double-sided edge trimming f) of the solidified fiber fabric is carried out in an area supported by a support element, preferably a circulating belt, in particular a press belt or a drying belt or a roller or a stationary strip.

[0026] In an alternative embodiment, the method is characterized in that the last application step e) and / or the first double-sided edge trimming f) of the solidified fiber fabric is carried out in an area free from a support element, preferably an unsupported area.

[0027] Advantageously, the final application e) of an agent, preferably a water-additive mixture, can be carried out in an unsupported area of ​​the fiber fabric. The fiber fabric is guided in a free stretch without support elements. If the final application e) is carried out in an unsupported area, no further components of the fiber fabric can be contaminated or soiled by the applied agent.

[0028] In an alternative embodiment, the method is characterized in that the two edge strips are returned to the low-water or dry raw material processing plant via a return device and recycled, or the two edge strips are fed to another use, in particular heat generation.

[0029] In an alternative embodiment, the method is characterized in that a second one- or two-sided edge trimming g) is carried out by means of a second one- or two-sided edge cutting device, in particular a second one- or two-sided edge strip removal, preferably a second one- or two-sided edge strip extraction, before the first application step c) and before the consolidation step d).

[0030] Advantageously, a second one- or two-sided edge trimming before the first application step c) and before the consolidation step d) further reduces the width of the two edge strips of the first edge trimming f) that are wetted with a solvent, thus reducing the amount of consolidated and solvent-wetted edge strips to be recycled. The fiber layup is initially laid with a width BF1 by a dry forming device. The first two-sided edge trimming can very easily trim the still unconsolidated or slightly consolidated fiber layup, which consists of only single fibers and / or fiber bundles, to a reduced width BF2. A return channel to the upstream raw material processing plant or recycling by the upstream raw material processing plant is possible without further or minimal processing of the edge trimming, thus increasing the efficiency of the manufacturing process.

[0031] In an alternative embodiment, the method is characterized in that the second one- or two-sided edge trimming g) is set and controlled in the transverse direction during the ongoing operation of the fiber web system.

[0032] In an alternative embodiment, the method is characterized in that a controlled variable is a measured application width of the last application step e), which is recorded by an online measuring system downstream of the last application step e).

[0033] Advantageously, in a two-stage edge trimming process, an online control loop is implemented with a measuring system downstream of the final application step, preferably an optical (video, laser), acoustic (ultrasound), or wave-based (microwave, IR) measuring system. This allows the amount of edge trim from the edge strips that is solidified and wetted with a reagent to be reduced to a minimum. This means that the regeneration effort for removing the reagent or dissolving the solidification can be reduced, and the majority of the edge trim from the first edge trimming stage, which contains only clean and slightly solidified single fibers and / or fiber bundles, can be easily returned to the raw material processing plant without prior regeneration or further processing.

[0034] In an alternative embodiment, the method is characterized in that the fibrous web is produced at a speed of greater than or equal to 150m / min, in particular greater than or equal to 250m / min, preferably greater than or equal to 400m / min.

[0035] In an alternative embodiment, the total amount of agent applied in the process is limited to less than 30%, preferably less than 20%.

[0036] In an alternative embodiment, the agent, particularly the strength-enhancing agent, can be applied in liquid, vapor, and / or powder form. The agent can thus be applied as a fluid, vapor, and / or powder.

[0037] In an alternative embodiment, the total amount of agent is divided into at least two application steps, preferably three application steps. This is particularly advantageous if the first application step is arranged directly before a, preferably mechanical, hardening step, and the second application step, in particular with a water-additive mixture, wherein the additive is an adhesive or a wet-strength agent, is only carried out after the, preferably last, hardening step. Preferably, after the last application step, the further process is free of further, preferably mechanical, hardening steps.

[0038] The amount of agent applied in the first application step is significantly lower compared to the second application step. The amount of agent in the first application step is limited to a small quantity of less than 30%, particularly less than 25%, preferably less than 20%, based on the total amount of agent used in the manufacturing process. This enables particularly efficient consolidation of the fiber web in the immediately following consolidation step.

[0039] In a preferred embodiment, this can be achieved, for example, by limiting the total amount of the agent to less than or equal to 30% of the overall process, as follows: In the first application step c), a maximum of 20% of the agent is applied. With a maximum total amount of the agent of 30% of the dry weight of the fiber web, this means that a maximum of 6% agent, preferably a maximum of 6% water, and thus a maximum of 6% moisture, is introduced into the fiber web before the consolidation step d). This significantly increases the efficiency of the subsequent consolidation and, preferably, structuring of the fiber layup, and consequently allows for significantly higher strength values ​​and high absorption values ​​to be achieved compared to a higher application amount that would otherwise be typical. The remaining 24% moisture is applied in the following second, and preferably third, application steps, preferably as a water-additive mixture.

[0040] The low concentration of the agent, less than 30%, preferably less than 20%, in the first application step c) proves particularly advantageous when considering the ratio of achievable strength to total energy consumption. An optimum has been found in this range, such that increasing the concentration of the agent, preferably water, in the first application step c) does not result in a significant increase in the strength values ​​of the fiber web.

[0041] It is assumed that, particularly when using pure water, highly efficient hydrogen bonds form in the fiber structure using this method.

[0042] In an alternative embodiment, each application step is followed by a consolidation step; this increases the penetration depth and bond of the applied agent with the fiber fabric or fiber web, and thus the strength properties of the fiber web.

[0043] In an alternative embodiment, an application step of the agent can also be carried out directly with a consolidation step. For this purpose, for example, a type of roller application unit is provided with a pre-application of the agent onto one of the support elements of the consolidation device, such that a subsequent transfer of the agent applied to the support element onto the fiber fabric is possible, with simultaneous consolidation of the fiber fabric.

[0044] The solidification device can advantageously be designed as a calender, whereby a simple press gap configuration with two or more rollers is conceivable.

[0045] Likewise, a vertical arrangement of three or more rollers is conceivable in which the fiber fabric or the fiber web is guided in a meandering pattern.

[0046] In an alternative embodiment, in the first application step c) before a solidification step d), the applied agent is preferably pure water.

[0047] This has a beneficial effect on the basic strength of the fiber fabric by forming hydrogen bonds (OH bonds) and can penetrate further into the fiber fabric with a subsequent strengthening step d).

[0048] Another advantage is that no pollution is caused by pure water.

[0049] In an alternative embodiment, the process is characterized in that, in the first application step c) prior to the solidification step d), the agent is a water-additive mixture, a water-vapor mixture, or a powder, and the additive is a drying agent. The drying agent is preferably a starch or sodium carboxymethylcellulose (CMC). If the drying agent is a starch, cationic starch such as maltodextrin is preferably used. The drying agent can be applied as a fluid, vapor, and / or powder.

[0050] Advantageously, dry strength agents are suitable for regulating the dry strength of the manufactured fiber web in its dry state.

[0051] Dry setting agents are also suitable for application prior to solidification, as they have a lower tendency to stick than adhesives or wet setting agents and therefore a lower tendency to become soiled.

[0052] In an alternative embodiment, the method is characterized in that, in the last and / or penultimate application step e) after the solidification step d), the applied agent is a water-additive mixture, a vapor-additive mixture, or a powder, and that the additive is an adhesive and / or a wet-strength agent. The wet-strength agent can be applied as a fluid, vapor, and / or powder.

[0053] The adhesive can be made from components of latex, such as ethyl vinyl acetate (EVA), but is not limited to the use of EVA.

[0054] The wet strength agent can be selected, for example, from components of amine-epichlorohydrin resins, preferably poly(aminoamide)-epichlorohydrin (PAE) resins; however, its use is not limited to these components.

[0055] Combinations of adhesive and wet-strength agents such as EVA and PAE are also conceivable, with the PAE content preferably being significantly lower than the EVA content.

[0056] The adhesives and / or wet-strength agents used should be biodegradable and free of harmful microplastic components.

[0057] In an alternative embodiment, the method is characterized in that the produced fibrous web contains an additive content of less than or equal to 6.5%, preferably less than or equal to 5%, in particular less than or equal to 1.5%, of the dry mass of the fibrous web.

[0058] In an alternative embodiment, the process is characterized by the fact that the adhesives and / or wet-strength agents in the total amount of the water additive are limited to less than or equal to 6.5%, in particular less than or equal to 5%, preferably less than or equal to 1.5%, of the mass of the produced fiber web. This has a beneficial effect on the ecological footprint, and the tendency to become soiled is also reduced by the limited use of additives.

[0059] It is currently anticipated that newly researched components could be used if they become established on the market and exhibit specific properties. These properties include, for example, suitability for dry forming processes, improved biodegradability, and low viscosity without the addition of a high proportion of water. Research activities on wet-strength agents are currently underway and point to a potential new additive, which could represent a novel invention.

[0060] In an alternative embodiment, the method is characterized by the fact that in the last application step e) the agent is applied to the solidified fiber web in a flat, covering layer.

[0061] Advantageously, a full-surface application of the agent is planned in the last and / or penultimate application step after final consolidation. This means that the agent is applied continuously in both the MD and CD directions. Consequently, the consolidated high-pressure and low-pressure zones of the fiber web are treated. Application is particularly beneficial in the less densely compacted low-pressure zones. Compared to the high-pressure zones, the low-pressure zones have a significantly higher absorption rate and can absorb a sufficient quantity of agent. The final fiber web can thus be precisely tailored to its parameters.

[0062] In an alternative embodiment, the process is characterized by the fact that, after the last and / or penultimate application step, the consolidated fiber fabric is produced without further consolidation. Advantageously, a water-additive mixture with an adhesive and / or wet-strength agent is applied as an additive in the last and / or penultimate application step. The water-additive mixture is applied to the already consolidated and structured fiber fabric in a continuous, covering layer, whereby a portion of the water-additive mixture can penetrate the low-pressure zones of the consolidated fiber fabric and consequently develop high wet strength there. This has a slightly detrimental effect on the feel properties of the fiber web, but results in significantly improved wet strength and also a reduced tendency to pill. The reduced tendency to pill is noticeable to the end user as less material sticking to the hands or...Fiber web pills or lint left behind after use.

[0063] Another portion of the agent is applied in the high-pressure zones, which, however, results in only a slight to no increase in the strength of the fiber web. This is due to the already significant consolidation of the fiber layup in the high-pressure zones, which limits the penetration of the wet-strength agent into the fiber layup.

[0064] Advantageously, the applied water-additive mixture, preferably an adhesive and / or wet-strength agent, no longer adversely affects the service life of downstream consolidation devices, thus avoiding, for example, the need for more downtime for maintenance and cleaning. Furthermore, the machine speed can be increased because the fiber webs, which would otherwise unintentionally adhere to a downstream consolidation device, are no longer dragged along.

[0065] In an alternative embodiment, the method is characterized by the fact that a penultimate application step is carried out on the same side of the solidified fiber fabric, with respect to the first application step.

[0066] In an alternative embodiment, the method is characterized in that the penultimate application step is carried out on the opposite side of the solidified fiber fabric, with respect to the last application step.

[0067] Advantageously, the solidified fiber fabric can be applied from both sides with a medium, in particular a water-additive mixture.

[0068] In an alternative embodiment, the method is characterized by the fact that in the last application step, the amount of applied agent essentially corresponds to the amount in the penultimate application step. Preferably, the amount is distributed essentially symmetrically, i.e., 50:50. Advantageously, this also achieves a uniform distribution of the applied agent in the z-direction (thickness) of the consolidated fiber web, and consequently, the strength values ​​and quality parameters of the produced fiber web are also homogenized. The uniform penetration depths on both sides of the fiber web lead to more homogeneous strength properties of the fiber web.

[0069] In an alternative embodiment, the method is characterized in that, in the last application step, the quantity of the applied agent is adjusted to be greater or less than the quantity applied in the penultimate application step. Preferably, the quantity is applied in a higher proportion on one side than on the opposite side, for example 60:40, more particularly 70:30.

[0070] Advantageously, an asymmetrical distribution of the quantity can result in a preferred side with higher strength values ​​for certain types of fiber webs.

[0071] In an alternative embodiment, the method is characterized in that the last consolidation step of the fiber fabric is carried out with a pressure greater than 10MPa, in particular greater than 20MPa, preferably greater than 30MPa.

[0072] In an alternative embodiment, the method is characterized by the fact that in the last consolidation step, consolidation takes place over the entire width of the fiber fabric.

[0073] In an alternative embodiment, the method is characterized in that, in the last consolidation step, a structuring of the fiber fabric is carried out simultaneously, preferably to increase strength, such that a planar solidified fiber web with at least one high-pressure and at least one low-pressure zone is formed.

[0074] Advantageously, the fiber layup is structured using the final consolidation device, which can further increase the strength of the consolidated fiber layup, preferably by increasing its tensile strength. This simultaneous consolidation and structuring, compared to embossing, is primarily carried out not only for the optical properties of the fiber web, but also for achieving the desired strength properties. For the structuring process, it is important that the fiber web is guided on one side by a smooth support element and on the other side by a structured support element, so that a large proportion of the laid fibers in the highly consolidated area are oriented only in a preferred plane, for example, the MD-CD plane. Only in the low-consolidated or weakly consolidated area can the fibers bend out of this plane to achieve the necessary properties in this area.To preserve haptics and absorption.

[0075] A fibrous web structured and / or consolidated in this way has a greater thickness in the low-pressure zones than in the more highly consolidated high-pressure zones.

[0076] A fiber web structured and / or consolidated in this way is characterized by maintaining a constant basis weight distribution in the MD and CD directions. This differs from an embossing or structuring process, often referred to as "embossing" in the tissue industry, where the fibers are "bent" into the structure and the previously formed fiber layup with its existing fiber bonds partially dissolves as the fibers pull apart within the layup, resulting in different basis weights.

[0077] In an alternative embodiment, the method is characterized by the fact that a pre-solidification step is carried out before the first application step.

[0078] Advantageously, pre-consolidation is carried out before the first application step. This allows for the creation of a minimum strength in the fiber layup before the application of the reinforcing agent, thereby enabling higher application rates than without pre-consolidation. It also keeps the fibers of the fiber layup on the permeable forming belt during application. The pre-consolidation acts on the fiber layup across its entire transverse direction (CD) to generate an initial base strength, with only slight compression and consolidation of the fiber layup thickness.

[0079] In an alternative embodiment, the method is characterized in that, in the application steps, the applied agent is applied as a spray jet, droplets, mist, vapor, foam, curtain, and / or via a roller. Application as a spray jet is preferred.

[0080] In an alternative embodiment, the method is characterized in that, in the application steps, the agent is applied to the fiber fabric from one side, and that on the opposite side the fiber fabric is drawn in by a vacuum device, such that the agent applied on one side will penetrate deeper into the fiber fabric.

[0081] In an alternative embodiment, the method is characterized in that at least one heating step is carried out during the production of the fiber web, and that the at least one heating step dries the solidified fiber fabric without contact by means of an electrically heated heating device; preferably the heating device is designed by infrared heating elements or as a flow-through drying hood.

[0082] Advantageously, the heating step is carried out using a non-contact heating device, such as infrared elements and / or flow-through drying hoods. Non-contact drying ensures that the properties of the solidified fiber layup or web, such as its thickness (bulk) and / or absorbency, are not affected, or only minimally affected, during the drying process.

[0083] The solidified fiber web can be supported by a drying sieve during the heating step, or alternatively, it can be guided through the heating device unsupported.

[0084] In an alternative embodiment, a second, third and fourth heating step of the fiber web can be provided.

[0085] In an alternative embodiment, the method is characterized by the fact that a heating step is included in the last solidification step.

[0086] Advantageously, in the last consolidation step, the fiber fabric is additionally heated in such a way that the liquid agent, preferably water, applied to the fiber fabric in the first application step, evaporates in the consolidation gap on and / or in the fiber fabric and the agent in vapor form can penetrate further into the fiber fabric under simultaneously applied pressure.

[0087] This requires temperatures in the solidification device, preferably the calender rolls, which are essentially set just below, e.g., a maximum of 20°C above, the evaporation temperature of the agent applied in the first application step.

[0088] In an alternative embodiment, the method is characterized in that the fiber fabric reaches a temperature of 60°C to 250°C, preferably 75°C to 150°C, in the heating step.

[0089] The temperatures of the heating devices used must be adjusted to the machine speed and residence times so that the fiber layup can absorb sufficient heat and the applied agent can evaporate.

[0090] Temperatures of 60°C to 250°C, preferably 75°C to 150°C, have proven to be optimum for the small amounts of agent applied.

[0091] The task can also be accomplished by a machine for producing a fibrous web, preferably a tissue, paper or cardboard web or a nonwoven web, in particular a tissue web with a basis weight of 28 g / m². 2 up to 42 g / m² 2 , in particular for carrying out the procedure according to one of the preceding claims, comprising a) a raw material processing plant for the low-water or dry processing of cellulose-containing fibers, preferably virgin fiber pulp in bales and / or recycled fibers, into individual fibers and / or fiber bundles; and a fiber web plant for dry forming of the fiber web, comprehensively further b) a dry forming device for forming individual fibers and / or fiber bundles in an airflow into a planar fiber fabric with a support element, preferably permeable; and c) a first application device for applying an agent to the planar fiber fabric, in particular for applying water and / or a water-additive mixture; and d) a final consolidation device for consolidating the planar fiber fabric by applying pressure and / or temperature in a consolidation gap, into a fiber fabric that is consolidated, preferably over its entire surface, preferably with at least one low-pressure and at least one high-pressure zone; and e) a final application device for applying an agent, preferably a water-additive mixture, to the solidified fiber fabric having a fiber fabric width; released.

[0092] According to the invention, the machine is characterized in that the last application device is set such that the agent, in particular the water-additive mixture, is applied to the solidified fiber fabric with an application width less than or equal to the fiber fabric width (BF1, BF2) in front of the last application device, and that a first double-sided edge cutting device for producing two edge strips from the solidified fiber fabric is included, and that the first double-sided edge cutting device is arranged downstream of the last application device and is set such that the two edge strips each have a region with agent and each have a region free of agent.

[0093] In an alternative embodiment, the machine is characterized in that the first double-sided edge cutting device is a double-sided air jet cutting device or a double-sided longitudinal cutting device with at least one, preferably rotating, knife.

[0094] In an alternative embodiment, the machine is characterized in that it includes a second one- or two-sided edge cutting device, preferably a second one- or two-sided edge strip extraction device, and that this device is arranged in front of the first application device and in front of the last consolidation device.

[0095] In an alternative embodiment, the machine is characterized in that the second single- or double-sided edge cutting device, preferably the second single- or double-sided edge strip extraction device, is connected to a return channel to the raw material processing plant.

[0096] In an alternative embodiment, the machine is characterized in that at least one online measuring device is assigned to the first double-sided and / or the second single- or double-sided edge cutting device.

[0097] In an alternative embodiment, the machine is characterized by the fact that an online measuring device is assigned to the first double-sided edge cutting device.

[0098] In an alternative embodiment, the machine is characterized by the fact that a return device is assigned to the first double-sided edge cutting device.

[0099] In an alternative embodiment, the machine is characterized in that the return device is further assigned at least one means, preferably an air nozzle or a guide plate, for the targeted removal of the two edge strips.

[0100] In an alternative embodiment, the machine is characterized in that the return device can be connected to the raw material processing plant via a return channel, which includes an intermediate processing device.

[0101] In an alternative embodiment, the machine is characterized in that the last application device and / or the first double-sided edge cutting device is arranged in an area supported by at least one support element or in an area free of a support element, preferably in an unsupported area.

[0102] In an alternative embodiment, the machine is characterized in that the at least one support element is wider in the transverse direction than the fiber layup width or the fiber web width.

[0103] In an alternative embodiment, the machine is characterized in that the at least one support element is a circulating belt, in particular a forming belt or a press belt or a drying belt, or a roller or a fixed bar.

[0104] In an alternative embodiment, the machine is characterized by the fact that the support element extends across the entire width transversely to the direction of travel or is arranged only in an edge area of ​​the fiber fabric or the fiber web.

[0105] In an alternative embodiment, the machine is characterized in that the last consolidation device is formed from a first and at least one second support element, and that a contact surface with the fiber fabric of the first support element comprises at least one raised press rib and is further designed such that the fiber fabric is consolidated over its entire surface in such a way that at least one low-pressure zone and at least one high-pressure zone are formed in the fully consolidated fiber fabric, and that the at least one high-pressure zone is generated by the at least one press rib raised to the contact surface of the first support element.

[0106] In an alternative embodiment, the machine is characterized in that the last solidification device comprises a heating device, preferably in the form of a heated first and / or a heated second support element.

[0107] In an alternative embodiment, the machine is characterized in that the final solidification device comprises a structuring device, preferably in the form of a structured first support element.

[0108] In an alternative embodiment, the machine is characterized by the fact that the final consolidation device consolidates the fiber fabric across the entire surface of a press width.

[0109] In an alternative embodiment, the machine is characterized by the fact that the pressing width maintains a distance in the transverse direction from the edge of the consolidated fiber fabric.

[0110] In an alternative embodiment, the machine is characterized by the fact that the fiber layup width is set larger than the application width, and the application width is set larger than the press width.

[0111] In an alternative embodiment, the machine is characterized in that the fiber web system includes at least one heating device for directly or indirectly heating and / or drying the fiber web or the consolidated fiber web applied with a means.

[0112] In an alternative embodiment, the machine is characterized in that the at least one heating device is arranged after the last solidification device, preferably and after the last application device.

[0113] In an alternative embodiment, the machine is characterized in that the at least one heating device is a flow-through drying device and / or an IR drying device; preferably, the at least one heating device is electrically heated.

[0114] In an alternative embodiment, the machine is characterized by the fact that at least one further heating device is arranged before and / or after the last solidification device.

[0115] In an alternative embodiment, the machine is characterized in that a pre-solidification device is arranged after the dry forming device and before the last solidification device, preferably or before a transfer of the fiber layup from the support element of the dry forming device.

[0116] In an alternative embodiment, the machine is characterized in that the first application device is arranged in front of the last solidification device.

[0117] In an alternative embodiment, the machine is characterized in that the first application device is arranged below the fiber fabric, so that the fiber fabric is applied from below, against gravity, by means of means.

[0118] In an alternative embodiment, the machine is characterized by the fact that a vacuum box is assigned to the first application device on its opposite side of the fiber fabric. It is advantageous if the agent applied on one side of the fiber fabric can penetrate through or into the fiber fabric.

[0119] In an alternative embodiment, the machine is characterized in that the first application device is designed such that the fiber fabric is applied from one side or from both sides by means of means.

[0120] In an alternative embodiment, the machine is characterized in that the last application device is arranged after the last solidification device.

[0121] In an alternative embodiment, the machine is characterized by the fact that the last application device is divided into a second and a third application device.

[0122] In an alternative embodiment, the machine is characterized in that the second application device applies the solidified fiber fabric from a different side than the third application device.

[0123] In an alternative embodiment, the machine is characterized in that the application width of the last application device is set to be less than or equal to the fiber layup width (BF1, BF2) immediately before the last application device at a distance from both edges of the solidified fiber layup of greater than or equal to 10 mm, in particular greater than or equal to 15 mm, preferably greater than or equal to 20 mm.

[0124] The invention expressly extends to embodiments which are not given by combinations of features from explicit cross-references of the claims, whereby the disclosed features of the invention can be combined arbitrarily with one another - insofar as this is technically sensible.

[0125] Further features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the drawing.

[0126] The invention will be explained below with reference to the following figures. Fig. Figure 1 shows a schematic representation of a raw material processing plant 2 for the low-water processing of cellulose-containing fibers 200; Fig. 2a and Fig. Figure 2b shows a schematic representation of a fiber web plant 3 for the production of a dry-formed fiber web 309, wherein Fig. 2a a side view and Fig. 2b is a top view.

[0127] To clarify the individual directions, a higher-level Cartesian coordinate system is used in the figures, which allows the individual directions to be illustrated. The x-direction represents the longitudinal extent, also known as the machine direction (MD). The y-direction corresponds to the direction perpendicular to the machine direction and is called the cross-direction (CD). The z-direction, on the other hand, corresponds to the vertical direction.

[0128] The Fig. 1 and Fig. Figures 2a / 2b show a possible embodiment of a machine 1 or a manufacturing method according to the invention in schematic representation.

[0129] The Fig. Figure 1 schematically represents a possible embodiment of a low-water processing plant or a low-water raw material processing plant 2, in which the individual fibers and / or fiber bundles 209 are processed from a raw material 200. The raw material 200 can consist, for example, of fiber-containing recycled material 200, 52 and / or of virgin fiber pulp 200 in bale form. An important aspect of the processing in the raw material processing plant 2 is sufficient comminution and / or fiberization of the virgin fiber pulp 200 in bale form, which is carried out by enclosed comminution devices 221, 222, 223 and / or fiberization devices 221, 222, 223.

[0130] After successful comminution and / or fiberization, at least one airflow 30, 90 is supplied to the individual fibers and / or fiber bundles 209, and the resulting air / fiber mixture is distributed via one or more distribution channels to a Fig. 2a shown, fiber web plant 3 for the production of a dry-formed fiber web 309.

[0131] It is also conceivable to have several raw material preparation plants 2 in parallel within the machine 1, which can supply a single fiber web plant 3. This is advantageous if a single raw material preparation plant 2 cannot produce the required quantity of individual fibers and / or fiber bundles 209, or if different types of cellulose-containing fibers 200 are used as raw material, for example, for a multi-layer fiber web 309.

[0132] An integrated, low-water raw material preparation system in machine 1, using a raw material preparation plant 2, is crucial for an industrial-scale manufacturing process with regard to economic and energy efficiency. Furthermore, the quality and properties of the produced dry-formed fiber web 309 can be directly influenced in the subsequent fiber web plant 3 by suitable means.

[0133] One challenge in integrated, low-water raw material processing on an industrial scale is transforming the very high production volumes of several thousand tons of finished fiber web 309 per year from a discontinuous to a continuous process. These high production volumes mean that the available raw material 200 should ideally be stored as compactly as possible to minimize inventory.

[0134] An important aspect of low-water raw material processing is that the required volume of the processed raw material 200 to 209 increases steadily until final processing in the fiber web plant 3. The increase in volume can typically range from a factor of 30,000 to 52,000, from the virgin pulp in bales 200 to the individual fibers and / or fiber bundles 209 dispersed in the air stream. Therefore, storage or intermediate storage 240 in the raw material processing plant 2 must be kept to a minimum and only implemented at the crucial processing steps.

[0135] Another aspect for the overall balance is to keep the availability of the supplied raw material 200 high and the cost low. Therefore, virgin fiber pulp 200 is preferably used in baled form rather than in rolls. A bale of virgin fiber pulp 200 typically consists of several sheets or strips of it.

[0136] In everyday language, due to the very widespread use of virgin fiber pulp in the form of rolls for end products, the term fluff pulp (or cellulose wadding) has become synonymous with virgin fiber pulp from rolls; however, this is not correct, as only a shredding of the rolls can produce a loosened fluff pulp.

[0137] Typically, with virgin pulp in roll form, a large part of the raw material preparation for the manufactured fiber web is already shifted into the virgin pulp production process itself. This is achieved by selecting more complex and elaborate manufacturing processes, which can be tailored to the composition of the pulp with additives for the production of the final fiber web. More importantly, they also place lower tolerances on the mass distribution of the roll material compared to baled material, as this is necessary for the known, simplified fiber web production process to provide a continuous mass flow.

[0138] It is also common practice to mix additives, such as "debonding agents", into rolled goods, which facilitate the separation of the fibers and counteract a renewed accumulation of the fibers in the further manufacturing process; this is usually not the case with baled goods or is reduced to a minimum.

[0139] Fresh pulp in bale and roll form typically has similar material density values ​​of around 600 - 960 kg / m³. 3 However, due to its cylindrical shape, the roll typically requires up to twice the storage space for storing the same amount of virgin fiber pulp compared to the essentially cubic shape of a bale.

[0140] Fresh fiber pulp in bale form is therefore characterized, compared to roll form, by a smaller storage volume or a higher concentration of fibers per cubic meter of storage space.

[0141] Concentration or density in a process typically describes the amount of undissolved material in a fiber suspension. Here, however, it refers to the amount of dissolved or present fiber material or other substances such as additives in one cubic meter of storage volume, or, in the case of a process step, the amount in one cubic meter of air. The material density values ​​of the virgin pulp or the fibers and / or fiber bundles remain essentially constant throughout the entire process.

[0142] For example, virgin pulp in bale form has a fiber concentration of essentially 99-100%, or in other words, one cubic meter of storage space is filled with 99-100% virgin pulp in bale, sheet, or shred form. Virgin pulp in roll form, on the other hand, has a lower fiber concentration of around [missing value] per cubic meter of storage space.

[0143] The lower storage volume allows for optimization of transport and storage, which is necessary for the large target quantities per day or per year in order to produce a competitive 309 fiber web.

[0144] A coupling of the two manufacturing processes of the low-water raw material preparation 2 and the fiber web plant 3 is an important component for the production of high-quality fiber webs 309, both of which can be coordinated, controlled and regulated via a higher-level control and regulation device 60.

[0145] The low-water raw material preparation process or raw material preparation plant 2 is characterized by a multi-stage comminution 221, 222, 223 of the discontinuously supplied raw material 200, whereby at the end of the low-water raw material preparation process 2, an airflow containing dispersed individual fibers and / or fiber bundles 209, tailored to the subsequent fiber web plant 3, can be continuously provided. The low-water raw material preparation process or raw material preparation plant 2 and the subsequent fiber web plant 3 are free of any intermediate storage of the individual fibers 209 and are thus provided to the fiber web plant 3 "on demand".

[0146] The general term "raw material 200" is used for cellulose-containing fibers 200, preferably virgin fiber pulp as bales 200 and / or recycled fibers 200, 52. The recycled fibers can, on the one hand, be obtained from the fiber web plant 3 itself as very high-quality recycled virgin fiber pulp 52, 110, and / or, on the other hand, it can be provided that recycled material from waste paper is used to further improve the overall balance of the manufacturing process.

[0147] The discontinuously supplied raw material 200 is typically fed as bales 200 via conveyor belts 220 to a first comminution device 221. The first comminution device 221, preferably a first shredder 221, is designed such that it can perform a first comminution of the bales 200 into coarse chips, shreds or chips 201.

[0148] For example, a bale of 200 mm virgin fiber pulp can consist of numerous stacked 200 mm pulp sheets. This pulp is NBSK pulp, the type typically used for wet-process paper, board, or tissue production. The starting material usually has a density of around 920 kg / m³. 3 The individual cellulose sheets have a thickness of approximately 1.5 mm. One to five of these cellulose sheets are always fed simultaneously in a substantially horizontal direction to a first comminution device 221, preferably a shredder 221.

[0149] The chips 201 are then fed to a cleaning device 230, whereby any unwanted components (so-called "rejects") still contained in the chips 201, such as metals, contaminants and / or packaging residues, can be filtered out, and after the cleaning device 230, preferably designed as a cyclone separator 230, cleaned chips 202 are available.

[0150] These cleaned chips 202 are temporarily stored in a larger memory 240, preferably configured as a silo 240 or vertical silo 240. This is preferably the only large memory 240 in the machine 1.

[0151] Additionally, even with a single, larger storage unit (240), smaller micro-storage units may be present in the individual components of the raw material processing plant 2 or the fiber web plant 3, due to the design of the components. However, these micro-storage units are only suitable for supplying the process for several seconds, preferably minutes.

[0152] Advantageously, the storage unit 240 is arranged immediately after the cleaning 230 of the chips 201, whereby the increase in volume can be kept as small as possible; in addition, a maximum storage capacity of the storage unit 240 of greater than or equal to 30 min, in particular greater than or equal to 60 min, preferably greater than or equal to 90 min, and less than or equal to 120 min of the production of the fiber web plant 3 is provided.

[0153] The size of the storage unit 240 therefore depends on the produced basis weights and width of the fiber web 309 and the production speeds of the fiber web plant 3.

[0154] The design of the memory 240 is geometrically optimized to enable compact, low-air, volume-optimized storage of the cleaned chips 202.

[0155] Alternatively, after cleaning 230 of the chips 201 and before the memory 240, a conditioning device 260 or a conditioning process 260 of the cleaned chips 202 can be provided. In this process, a small amount of moisture is supplied to the chips 202, for example, to minimize or prevent dust formation and / or electrostatic charging. If this is provided, the moisture applied in such a case must be taken into account in the overall balance of machine 1.

[0156] Alternatively, additives can also be mixed into the chips 201 using the conditioning device 260.

[0157] The storage unit 240 is preferably designed as a vertical storage silo 240, wherein the weight of the cleaned chips 202 can advantageously allow for low compaction. Furthermore, at least one discharge device 241 is provided in the storage unit 240, which can enable continuous discharge of the cleaned chips 202. The discharge device 241 can constitute a separate subject matter of the invention.

[0158] To assist in the discharge of the cleaned chips 202 from the memory 240, an airflow 90 is added directly at the outlet of the memory 240, so that the cleaned chips 202 can be distributed and mixed in the airflow in a subsequent distribution channel and consequently easily transported to the second shredding device 222.

[0159] In an alternative embodiment, a return channel 50 for recycled material originating from the fiber web plant 3, for example fibers from an edge strip extraction device 52, can preferably be provided upstream of the second shredding device 222.

[0160] Alternatively, individual fibers and / or fiber bundles 209 filtered from the ambient air of machine 1 and not deposited can be added back in as recycled material before the second shredding device 222 via a return channel 50. This is particularly advantageous if the recycled material does not yet contain any additives and thus meets the qualitative requirements without further processing steps.

[0161] The second comminution device 222 or first fiberizing device 222 is preferably designed as a first hammer mill 222, in which the cleaned chips 202 are comminuted or fiberized until individual fibers with isolated nodes 205 are formed, which can then pass through a filter device included in the second comminution device 222.

[0162] By supplying an airflow 90 after the second comminution device 222, the discharge of the individual fibers with isolated nodes 205 from the second comminution device 222 is supported and the further transport as a fiber-air mixture 205 to the next device is carried out.

[0163] In an alternative embodiment, it can be provided that the individual fibers with isolated nodes 205, after leaving the second comminution device 222, are further processed or metered in a fiber processing device 250 to form a continuous mass flow of individual fibers with isolated nodes 206, to which an air flow 90 is then supplied and the further transport as a fiber-air mixture 206 to the next device is supported.

[0164] The fiber-air mixture 205 or 206, preferably the individual fibers with isolated nodes 205 from the second comminution device 222 or alternatively the continuous mass flow of individual fibers with isolated nodes 206, is fed to the third comminution device 223 or fiberizing device 223, which is preferably designed as a second hammer mill 223.

[0165] The third comminution device 223 commins or fiberizes the supplied fiber-air mixture 205 or 206 until only individual fibers and / or fiber bundles 208, essentially free of knots or with a small proportion of knots, are formed, which can then pass through a filter device included in the third comminution device 223.

[0166] To further reduce the single fiber concentration, an airflow 90 and / or a portion of the exhaust air from the vacuum boxes 3 included in the fiber web system is mixed with the individual fibers and / or fiber bundles 208, which are essentially free of knots, for web stabilization 32 (see also Fig. 2a).

[0167] The resulting high-resolution individual fibers or fiber bundles 209, essentially free of knots, are metered and continuously supplied via a distribution system or distribution channels of the fiber web system 3.

[0168] The individual fibers and / or fiber bundles 209 transported by the airflow are, as in the Fig. 2a further shown, fed into the following fiber web system 3 a dry forming device 4 and distributed evenly transversely to the machine running direction MD or in the transverse direction CD of the fiber web system 3.

[0169] Downstream of the dry forming device 4, at least two application devices 7 are provided, which can apply or wet a medium, preferably a water and / or a water-additive mixture, onto the fiber fabric 300 or the consolidated fiber fabric 305. The at least two application devices 7 are configured as a first application device 71 and at least one last application device 72, 73. As shown in Fig. Figure 2a shows that in the illustrated embodiment three application devices 71, 72, 73 are arranged, with an additional second application device 72 arranged between the first 71 and the last 73.

[0170] Furthermore, at least one consolidation device 8 is provided after the dry forming device 4, which can consolidate the fiber fabric 300. In the illustrated embodiment in Fig. 2a Two consolidation devices 8 are arranged. Preferably, a final consolidation device 81 is designed such that, in addition to consolidation of the fiber fabric 300, it can also structure and / or heat the fiber fabric. The structuring by the final consolidation device 81 is particularly useful for producing a tissue web with at least one low-pressure and one high-pressure zone, preferably a tissue web with a basis weight of 28 g / m². 2 up to 42g / m²2 , important.

[0171] To complete the continuously produced fiber web 309, a web-width winding unit 12 is arranged at the end of the fiber web system 3.

[0172] Preferably, at least one heating device 10 can be included in the fiber web system 3. It is advantageous if the at least one heating device 10 is arranged downstream of the application devices 7 to dry the applied agent. Preferably, the at least one heating device 10 is arranged upstream of the winding unit 12 of the finished fiber web 309, which is also included in the fiber web system 3.

[0173] The dry forming step 4 in the dry forming device 4 can be controlled and regulated by at least one control and regulating means, wherein the individual fibers and / or fiber bundles 209 in the dry forming device 4 are laid down, preferably partially by the force of gravity, onto a circulating, preferably permeable, support element 40 or a circulating, preferably permeable, forming belt 40 and form a, preferably still substantially unconsolidated, planar fiber fabric 300.

[0174] Furthermore, the dry forming device 4 can include a suction device 30, which can support the depositing of the individual fibers 209 onto a permeable support element 40 and / or control it as a further control and regulation means.

[0175] Preferably, the fiber layup 300 is measured in its mass distribution by at least one measuring device 61, preferably a mass measuring device 61 extending in the transverse direction CD, wherein this is used directly via the higher-level control and regulating device 60 as a control variable in the feed of the individual fibers without knots 209 from the raw material preparation plant 2, as well as in the control and regulating means included in the dry forming device 4 and preferably in the further control and regulating means included in the suction device 30, and is coordinated with each other.

[0176] The air 39 extracted by the suction device 30 may contain a certain quantity of individual fibers and / or fiber bundles 209. Therefore, it is advantageous if a large part, preferably up to 95%, of the air extracted by the suction device 30 is directly designed as a recirculation circuit 39, which is essentially fed directly back into the dry forming device 4 and thus efficiently enables the continuously added individual fibers and / or fiber bundles 209 to be broken down and the forming on the support element 40 to be improved, as well as the extracted individual fibers to be fed directly back into the corresponding production step.

[0177] In an alternative embodiment, after the first fiber layup 300 leaves the dry forming device 4, excess fibers in the z-direction (thickness) can be selectively and controlled removed from the surface of the first fiber layup in the transverse direction CD by a suction device 52 arranged in the transverse direction CD, so that a homogeneous thickness distribution in both the CD and MD directions can be achieved. This can be directly influenced in an extended control loop by the higher-level control device 60 via at least one measuring device 61 and / or a second measuring device 62.

[0178] Alternatively, the extraction device 52 can also be designed as a second one- or two-sided edge cutting device 52, preferably a second one- or two-sided edge strip extraction device 52 is provided, which specifically extracts the edge areas of the still unsolidified fiber fabric 300 coming from the dry forming device 4.

[0179] It is evident that the edge areas often exhibit significant variations in thickness compared to the main or central area of ​​the fiber web 300. Advantageously, this edge strip extraction 52 allows fresh, chemical-free recycled material to be fed directly back into the raw material processing plant 2 via a return channel 50 immediately after the dry forming device 4. This has a positive effect on the overall efficiency of the manufacturing process. Furthermore, it enables the production of an initial clean, one- or two-sided edge of the fiber web 300, which can make the initial edge trimming 51 after the final application device 73 and before the final winding 12 of the finished fiber web 309 more efficient.

[0180] In an alternative embodiment, two, three, or four consolidation devices 8 may be arranged, which successively consolidate and / or structure and / or heat the fiber fabric 300. The individual consolidation gaps of the consolidation devices may each be formed by their own support elements or may be combined, for example, in a multiple support element arrangement.

[0181] As in Fig. As shown in Figure 2a, in an alternative embodiment, the fiber fabric 300 deposited in the dry forming device 4 can pass through a pre-solidification device 83 before the first application device 71, in which the still unsolidified fiber fabric 300 receives a first full-surface pre-solidification or pre-compacting over the entire transverse direction CD or fiber fabric width BF1 or BF2 (see Figure 2a). Fig. 2b).

[0182] The application devices 71, 72, 73 are preferably designed as nozzle applicators which can spray the agent 70 in the form of a spray jet as droplets onto the fiber fabric 300, 305.

[0183] Alternatively, the application devices can also be designed in such a way that the agent is applied in the form of drops, foam, mist, vapor or powder.

[0184] Alternatively, a curtain applicator or a roller applicator can be provided, the roller applicator preferably being integrated into a consolidation device 8. In an application device 7 integrated into a consolidation device 8, a means with an applicator is first applied to, for example, a support element, and then, in the subsequent consolidation gap, the means is transferred to the fiber fabric 300.

[0185] Immediately before the winding 12 of the fiber web 309, the fiber web is dried by a heating device 10, preferably a contactless electric heating device 10. The contactless heating device 10 can be, for example, a hot air drying device 10, a flow-through drying hood 10, or a TAD heating device 10. Alternatively, the heating device 10 can also be, for example, equipped with infrared elements.

[0186] Advantageously, the properties of the fibrous web 309 with regard to its thickness, its feel properties and its absorption capacity can be maintained by means of a contactless heating device 10.

[0187] Due to the low overall moisture content, the length of the heating device 10 can be kept very compact compared to the usual dry sections from the wet forming processes, thus significantly reducing the overall length of the fiber web system 3 and infrastructure costs. Compared to the usual dry forming processes, the further reduced total amount of moisture-increasing agents used results in an advantageous, more compact design of the heating device 10.

[0188] In an alternative embodiment, at least one further heating device can be provided which heats the fiber fabric 300 before and / or in and / or after a consolidation device 8.

[0189] The at least one additional heating device integrated into a consolidation device 8 can, for example, be provided in a support element 811, 812 intended for consolidation. Heating below 250°C, in particular less than or equal to 100°C, preferably less than or equal to 80°C, is advantageous because the heating enhances the penetration depth and distribution of a medium, preferably water, applied in a first application step 71 within the fiber web 300, which can simultaneously result in more efficient consolidation and / or structuring. The temperature specifications refer to the temperature of the heating device used; the temperature applied to the fiber web or fiber web can be lower.

[0190] In the case of structuring in the last solidification device 81, the support element 811 is designed as a structured support element 811 with a surface structure.

[0191] The first application device 71 is arranged directly upstream of the solidification device 8. Furthermore, the first application device 71 applies a medium, preferably pure water, which means that the water is free of artificial or chemical additives.

[0192] Alternatively, the first application device 71 can also be provided for to apply an agent, preferably a water-additive mixture. If a water-additive mixture is applied to the fiber web 300 before consolidation 8, the additive is selected from the group of dry-strength agents, for example, a starch, to increase the strength in a dry state of the produced fiber web 309. The dry-strength agents are also suitable for application before consolidation, as they exhibit a lower tendency to stick than adhesives or wet-strength agents.

[0193] The application devices 71, 72, 73 are designed such that the fiber fabric 300 can be wetted over its entire surface with the agent. "Over its entire surface" means that the agent is applied substantially uniformly over the entire width or over the entire transverse direction CD of the fiber fabric.

[0194] In an alternative embodiment, a vacuum box 31 can be arranged on the respective opposite side of the fiber fabric 300 to the wetting side of the first, second and third application device 71, 72, 73, which draws in ambient air through the fiber fabric 300 and a permeable support element 40, 41, 42, preferably a permeable forming belt 40, a pressure belt 41 and / or a drying screen 42 on which the fiber fabric 300 is supported, by means of a negative pressure applied, preferably during the application.

[0195] This advantageously allows for controllable application during the application of an agent with regard to, for example, a greater penetration depth of the applied agent into the fiber fabric 300 or control of the quantities in the transverse direction CD and / or machine running direction MD.

[0196] Optionally, at least one moisture measuring device 63 and / or a measuring device for controlling the application of the agent, e.g., of an application width BA in the fiber web system 3, may be included, which can measure the applied agents on or in the produced fiber web 300 or 305 after the application device 7 or after drying 10. Preferably, the moisture measuring device 63 is arranged such that it can measure before or after the heating device 10.

[0197] Alternatively, a moisture measuring device 63 can be provided directly after each application device 71, 72, 73. The moisture measuring device 63 can be stationary or traversing. Furthermore, the moisture measuring device 63 can also be suitable for measuring other fiber web properties such as mass, thickness, formation, opacity, or other characteristics.

[0198] In Fig. 2b is a schematic top view of the enclosed fiber plant 3 in machine 1. Fig. 2a shown.

[0199] The schematic top view is shown at the level of the fiber web 309 to be produced, the fiber fabric 300, or the solidified fiber fabric 305.

[0200] The fiber layup 300 is deposited by the dry forming device 4 onto a support element, preferably a circumferential support element 40, and continuously formed. The circumferential support element 40 can be a forming belt 40.

[0201] The formed fiber fabric 300 is produced from left to right in the machine direction at a machine speed. The fiber fabric 300 is transferred to further circulating support elements 41, 42, for example, a press belt 41 and a drying belt 42. For the further transport of the fiber fabric, the circulating belts move from left to right in the illustrated direction 22. The support elements are always wider than the fiber fabric 300, 305 and the fiber web 309 to ensure continuous support.

[0202] The fiber layup 300 is deposited in a first fiber layup width BF1 by the dry forming device 4.

[0203] Optionally, a second single- or double-sided edge-cutting device 52 can be arranged downstream of the dry forming device 4. This device can trim the still unconsolidated fiber layup 300 in the first fiber layup width BF1 to a smaller fiber layup width BF2. In the case of this optional second edge-cutting device 52, for example, an edge strip extraction unit 52 is used. This second single- or double-sided edge-cutting device 52 is preferably arranged upstream of a consolidation device 8, here upstream of a pre-consolidation device 83.

[0204] Optionally, a pre-solidification device 83 can perform a surface pre-solidification of the fiber layup 300 over the full first BF1 or second fiber layup width BF2 after the dry forming device 4 and before the last solidification device 81.

[0205] A first application device 71 preferably applies an agent, preferably water or a water-additive mixture, to the underside of the fiber fabric 300 which is guided overhead or suspended, wherein the additive can be a dry strengthening agent. The first application device 71 is preferably arranged directly upstream of the last consolidation device 81.

[0206] The final consolidation device 83 consolidates the fiber fabric 300 into a consolidated fiber fabric 305. In addition to pressure, the final consolidation device 83 can optionally introduce temperature into the fiber fabric 300. Preferably, the final consolidation device 83 can also introduce a structure into the fiber fabric.

[0207] The last consolidation device 83 preferably acts on the entire width of the fiber fabric 300; alternatively, the effective width can also be reduced, and the consolidation width BP. The unconsolidated edge area of ​​the consolidated fiber fabric 205 is then preferably cut off by the first double-sided edge cutting device 51.

[0208] The application steps are carried out by the three application devices 71, 72, 73 on the underside and top side of the fiber fabric 300 and / or the consolidated fiber fabric 305.

[0209] Further possible changes in width, for example due to the effects of a solidification device 8 or a heating device 10 or a rolling device 12, may be present, but will be addressed in the course of the Fig. 2b neglected.

[0210] The fiber fabric 300 and the reinforced fiber fabric 305 are limited in their extent in the transverse direction CD or in their width by a fiber fabric edge 106.

[0211] In the case of a consolidation width BP which is smaller compared to the fiber layup width BF1 or BF2, a distance 113 is formed from the fiber layup edge 106 to the consolidated area of ​​the fiber layup 305 shown.

[0212] When the edge is trimmed by the first double-sided edge cutting device 51, which is smaller compared to the fiber layup width BF1 or BF2, an edge strip width 112 is formed from the fiber layup edge 106 of the fiber layup 305 to the fiber web 309 with a final manufactured fiber web width BF3.

[0213] The double-sided edge strip 105 formed by the first double-sided edge cutting device 51 has a medium-applied area 107 and a medium-free area 108.

[0214] The two edge strips 105 are removed from the fiber web system by a return device 110; preferably, the two edge strips 105 are fed to the raw material processing plant 2 upstream of a cleaning device 230 and / or to an upstream processing plant (not shown). Alternatively, the two edge strips 105 can be subjected to another recycling process, for example, thermal recycling.

[0215] In the case of an application width BA of the last application device 73 which is smaller compared to the fiber fabric width BF1 or BF2, a distance 111 is formed from the fiber fabric edge 106 to the applied area of ​​the fiber fabric 305.

[0216] The fiber web system 3 is designed for a high, continuous production speed of ≥ 250 m / min, preferably ≥ 400 m / min. The width of the continuously produced fiber web can range from ≥ 0.5 m to ≤ 10 m, depending on the operator's requirements. For example, tissue machines can be configured as "single width" or "double width," as is common on the market, with a width of approximately 3 m for a "single width" configuration.

[0217] This dimension, in combination with the typically produced basis weights of greater than or equal to 5g / m², 2 up to and including 200 g / m² 2 , preferably of greater than or equal to 10 g / m² 2 up to and including 80 g / m² 2 , especially of 28 g / m² or greater 2 up to and including 42 g / m² 2, directly contribute to the necessary raw material quantity, storage volume, transport capacities and transport routes, and highlight the importance in the proposed process of the need for direct integration of the cost-effective raw material processing plant 2. Reference symbol list 1 machine 2 Raw material processing plant 3 Fiber web plant 4 Dry forming device 7 Application device for a medium 8 Solidification device 10 Heating device 12 Roll-up 22 Direction of travel of the support elements 30 Suction device of the dry forming device 31 Vacuum Box - Application Device 32 Vacuum Box for Track Stabilization 39 Recirculation circuit of the suction device of the dry forming device 40 Support element, preferably a forming belt 41 Support element, preferably a press band 42 Support element, preferably a drying sieve 50 feedback channel 51 Edge cutting device 52 Extraction device, edge strip extraction 60 Control and regulating device 61 Mass distribution measuring device 62 Mass distribution measuring device 63 Measuring device for measuring the moisture content and / or the application width BA of the fiber fabric 70 agents in liquid, vapor or powder form 71 first application device 72 second application device 73 third application device 81 last solidification device 811 Support element 812 Press element 83 Pre-solidification device 90 airflow 105 edge strips 106 Fiber web edge, fiber web edge 107 Area on the verge with medium 108 Area on the verge, center line clear 110 Return device 111 Width of the area of ​​the fiber layup free from a means 112 Width of the edge strip 113 Width of the unconsolidated area of ​​the fiber layup 200 bales of goods 201 shredded baled goods, chips 202 cleaned chips 205 individual fibers with scattered knots 206 continuous mass flow of single fibers with scattered nodes 208 individual fibers essentially free of knots 209 individual fibers essentially free of knots, high-resolution in a fiber-air mixture 221 First shredding device, shredder 222 Second comminution device, preferably a fiberizing device, in particular a first hammer mill 223 Third comminution device, preferably a fiberizing device, in particular a second hammer mill 230 Cleaning device, cyclone 231 air 240 storage 241 Discharge device 250 fiber processing device 260 Conditioning of the cleaned chips 300 fiber layups after dry forming device 305 Consolidated fiber fabric after the last consolidation device 309 Fibre web BA Application range BF1 Fiber layup width after dry forming device BF2 fiber layup width after dry forming device during second edge trimming BF3 Final Fiber Web Width BP Press width MD Machine direction of travel CD machine transverse direction z Vertical direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2019 / 137 667 A1

[0005] DE 1 965 716 A1

[0006]

Claims

[1] Method for producing a fibrous web (309), preferably a tissue, paper or cardboard web or a nonwoven web, preferably a tissue web with a basis weight of 28 g / m² 2 up to 42 g / m² 2 , comprising the following steps: a) low-water or dry raw material processing of cellulose-containing fibers (200), preferably virgin fiber pulp as bales (200) and / or recycled fibers (200, 110, 50), into single fibers and / or fiber bundles (209) by means of a raw material processing plant (2); b) Forming the individual fibers and / or fiber bundles (209) in the airflow to form a planar fiber fabric (300) with a fiber fabric width (BF1, BF2) in the transverse direction (CD) on a, preferably permeable, support element (40) by means of a dry forming process using a dry forming device (4); c) first application of an agent, in particular a liquid and / or vaporous and / or powdery agent, preferably water and / or a water-additive mixture and / or a powder and / or a steam, to the fiber fabric (300) by means of a first application device (71); d) Consolidating the planar fiber fabric (300) by, preferably over the entire surface, applying pressure in a consolidation gap, to form a consolidated fiber fabric (305) by means of a final consolidation device (81); e) a final, preferably full-surface, application of an agent, in particular a liquid and / or vaporous and / or powdery agent, preferably a water-additive mixture and / or a powder and / or a water-additive vapor, in an application width (BA) in the transverse direction (CD) by means of a final application device (72, 73) onto the solidified fiber fabric (305) having a fiber fabric width (BF1, BF2); characterized by , that the last application step e) is carried out after a last solidification step d) and that the application width (BA) in the last application step e) is set to be less than or equal to the fiber layup width (BF1, BF2) and that the consolidated fiber layup (305) after the last application step e) is cut by a first double-sided edge trim f) in transverse direction (CD) by means of a double-sided edge cutting device (51) into two edge strips (105) and the fiber web (309) such that the two edge strips (105) each have an area (107) applied with agent, preferably a water-additive mixture and / or a powder and / or a water-additive vapor, and each have an agent-free area (108). [2] Method according to claim 1, characterized by , that the last application step e) and / or the first double-sided edge trimming f) of the consolidated fiber fabric (305) is carried out in an area supported by a support element, preferably a circulating belt (40, 41, 42), in particular a press belt (41) or a drying belt (42) or a roller or a fixed strip. [3] Method according to claim 1 or 2, characterized by, that the last application step e) and / or the first double-sided edge trimming f) of the solidified fiber fabric (305) is carried out in an area free from a support element, preferably an unsupported area. [4] Method according to any one of the preceding claims, characterized by , that the two edge strips (105) are returned to the low-water or dry raw material processing plant (2) via a return device (110) and recycled, or that the two edge strips (105) are used for another purpose, in particular for heat generation. [5] Method according to any one of the preceding claims, characterized by, that a second one- or two-sided edge trimming g) is carried out by means of a second one- or two-sided edge cutting device (52), in particular a second one- or two-sided edge strip removal (52), preferably a second one- or two-sided edge strip extraction (52), before the first application step c) and before the consolidation step d). [6] Method according to claim 5, characterized by , that the second one- or two-sided edge trimming g) is set and controlled in the transverse direction (CD) during the ongoing operation of the fiber web plant (3) and that a controlled variable is a measured application width (BA) of the last application step e), which is recorded by an online measurement system (63) downstream of the last application step e). [7] Machine (1) for producing a fibrous web (309), preferably a tissue, paper or cardboard web or a nonwoven web, in particular a tissue web with a basis weight of 28 g / m² 2 up to 42 g / m² 2 , in particular for carrying out the procedure according to one of the preceding claims, comprising a) a raw material processing plant (2) for the low-water or dry processing of cellulose-containing fibers (200), preferably virgin fiber pulp in bales (200) and / or recycled fibers (200, 110, 50), into single fibers and / or fiber bundles (209); and a fiber web plant (3) for dry forming the fiber web (309) further comprising b) a dry forming device (4) for forming the individual fibers and / or fiber bundles (209) in the airflow into a planar fiber fabric (300) with a support element (40), preferably permeable; and c) a first application device (71) for applying an agent to the planar fiber fabric (300), in particular a liquid and / or vaporous and / or powdery agent, preferably for applying water and / or a water-additive mixture and / or a powder and / or water vapor; and d) a final consolidation device (81) for consolidating the planar fiber fabric (300) by applying pressure and / or temperature in a consolidation gap into a, preferably fully consolidated, fiber fabric (305), preferably with at least one low-pressure and at least one high-pressure zone; and e) a final application device (72, 73) for applying an agent, in particular a liquid and / or vaporous and / or powdered agent, preferably for applying a water-additive mixture and / or a powder and / or a water-additive vapor, to the solidified fiber fabric (305) having a fiber fabric width (BF1, BF2); and characterized by , that the last application device (72, 73) is set such that the agent onto which the consolidated fiber fabric (305) with an application width (BA) less than or equal to the fiber fabric width (BF1, BF2) is applied before the last application device (72, 73) and that a first double-sided edge cutting device (51) for producing two edge strips (105) from the consolidated fiber fabric (305) is included and that the first double-sided edge cutting device (51) is arranged downstream of the last application device (72, 73) and is set such that the two edge strips (105) each have a median area (107) and a median-free area (108). [8] Machine according to claim 7, characterized by , that a second one- or two-sided edge cutting device (52), preferably a second one- or two-sided edge strip extraction device (52), is included, and that this is arranged in front of the first application device (71) and in front of the last consolidation device (81). [9] Machine according to claim 7 or 8, characterized by , that the last application device (72, 73) and / or the first double-sided edge cutting device (51) is arranged in an area supported by at least one support element or in an area free from a support element, preferably in an unsupported area. [10] Machine according to any one of claims 7 to 9, characterized by , that the last solidification device (81) is formed from a first (811) and at least one second support element (812, 41) and that a contact surface with the fiber fabric (300) of the first support element (811) comprises at least one raised press rib and is further designed such that the fiber fabric (305) is fully bonded in such a way that at least one low-pressure zone and at least one high-pressure zone are formed in the fully bonded fiber fabric (305), and that [11] Machine according to any one of claims 7 to 10, characterized by , that the fiber web system (3) includes at least one heating device (10) for directly or indirectly heating and / or drying the fiber web (300) or the fiber web (305) that has been consolidated with an agent. [12] Machine according to any one of claims 7 to 11, characterized by, that at least one further heating device is arranged before and / or after the last solidification device (81). [13] Machine according to any one of claims 7 to 12, characterized by , that a pre-solidification device (83) is arranged after the dry forming device (4) and before the last solidification device (81), preferably or before a transfer of the fiber layup (300) from the support element (40) of the dry forming device (4). [14] Machine according to any one of claims 7 to 13, characterized by , that the application width (BA) of the last application device (72, 73) is less than or equal to the fiber layup width (BF1, BF2) immediately in front of the last application device (72, 73) with a distance (111) from both edges of the solidified fiber layup (305) of greater than or equal to 10 mm, in particular of greater than or equal to 15 mm, preferably of greater than or equal to 20 mm.

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