Press arrangement and method for pressing a fibrous blanket.

Description

1 / 14 “PRESS ARRANGEMENT AND METHOD FOR PRESSING A FIBROUS BLANKET” Field of Invention

[0001] The present invention relates to a press arrangement for pressing a fibrous blanket, in particular a packaging paper blanket, comprising a main press with an extended press nip, the press nip having a length of at least 150 mm, preferably at least 190 mm. Furthermore, the present invention relates to a method for pressing a fibrous blanket, in particular a packaging paper blanket, as a test liner for packaging, wherein the fibrous blanket is guided through a main press with an extended press nip of at least 150 mm in length, preferably at least 190 mm in length.

[0002] Such a press arrangement and such a pressing method are described, for example, in document WO2017207475A1, the disclosure of which is incorporated herein by reference.

[0003] US patent 5,951,824 A further describes a press arrangement of this type, which can be operated with a line load of at least 1,200 kN / m. This document describes, among other things, a pressure profile that is established in the press nip when a paper wad passes through the press arrangement.

[0004] Machines for producing a fibrous mat generally have a press arrangement in which the fibrous mat is dehydrated or dehumidified by mechanical pressure. The press arrangement is usually located between the forming and drying sections. A particularly efficient type of mechanical dehydration can be achieved by means of the so-called extended press nip. The advantages of an extended press nip are well known: the press nip is flat and not essentially linear as in conventional roller presses. This means that the pressure exerted on the Petition 870250087490, dated 09 / 26 / 2025, page 33 / 64 2 / 14 of the fibrous mat to be dehydrated in the press nip does not start abruptly in the direction of operation, but can be continuously increased from a low to a high value. This reduces the risk of the fibrous mat being crushed in the press nip. This allows the fibrous mat to be dehydrated very efficiently in a prolonged press nip, preserving its volume.

[0005] For example, the fibrous web can be guided along with a felt or between two felts through the extended press nip, wherein the extended press nip can be formed in a so-called shoe press between a shoe press roll and a counter-roll. Unlike the production of woven webs, thickness or volume are less important in the production of paper webs, especially paper webs for packaging. Therefore, and due to the considerably higher basis weight of paper webs, especially paper webs for packaging, significantly higher line loads are used in the press, i.e., line loads of at least 500 kN / m.

[0006] The issues of energy costs and CO2 footprint play an increasingly important role in the production of fibrous mats. Energy consumption in the drying section, which is currently heated almost exclusively by gas, is a significant factor. To save energy and gas, it would be very advantageous if the fibrous mat from the upstream pressing arrangement already had the highest possible dry matter content. An obvious idea would be to simply increase the line load in the press arrangement to achieve a higher dry matter content. However, this approach has limited practical utility as it carries the risk of crushing the fiber to be dehydrated in the press nip. Furthermore, energy consumption in the press arrangement also increases with increased line load at the same machine speed, and with increased line load, investment costs increase as a considerably more robust structure is required. Petition 870250087490, dated 09 / 26 / 2025, p. 34 / 64 3 / 14

[0007] It is an objective of the present invention to reduce the energy costs and / or the CO2 footprint for the production of a fibrous blanket, in particular a packaging blanket.

[0008] This objective is achieved by the independent claims. The dependent claims refer to advantageous developments of the present invention.

[0009] Specifically, the objective is achieved by a generic press arrangement as described above, which is particularly characterized by the fact that the main press is designed in such a way that, when operated with a line load LL of at least 1,200 kN / m, it results in a line load ratio LLR of at least 0.69 and at most 1.52, wherein the line load ratio LLR is the quotient of a weighted line load WLL to the line load LL, wherein the weighted line load WLL is the result of an integration of the quadratic local pressure p(x)2 weighted with a weighting factor A over the press nip length x, wherein the weighting factor A is one divided by ten megapascals, and wherein the line load LL is the result of an integration of the local pressure p(x) over the press nip length x, so that the line load ratio LLR is given by the following formula: WLL fA'p^dx= LL fp(x)dx fp(x)dx

[0010] For better understanding, refer to the diagram in Figure 3, which illustrates, in a purely schematic way, how the LLR line load relationship can be easily determined and understood. First, the actual pressure profile p(x) is determined, that is, the pressure profile acting on the length x of the extended contact point of the main press. In the example presented, the main press has an extended press nip of 260 mm. Furthermore, for simplicity, it is assumed that the local pressure Petition 870250087490, dated 09 / 26 / 2025, page 35 / 64 4 / 14 p(x) along the extended press nip increases linearly from 0 MPa at the beginning of the extended press nip at x = 0 mm to 12 MPa at the end of the extended press nip at x = 260 mm, resulting in a straight line as the pressure profile p(x). The determination of the local pressures, which together result in the pressure profile, can be performed, for example, using a pressure measuring film inserted into the extended press nip before pressure is applied by the main press. The pressure measuring film then measures, for example, using the piezoelectric effect, exactly where the local pressure is applied on the press nip. The pressure in the transverse direction of the machine is generally constant, therefore only the pressure profile in the machine direction, i.e., along the length of the extended press nip, is important.At most, there may be a slight change in pressure in the transverse direction of the machine in the side edge area, although these effects in the side edge area are disregarded here. Pressure measuring films with various resolutions are commercially available, for example, from Fujifilm under the Prescale brand. Measurements should preferably be taken before starting the press, after installing a new felt, especially a new and still dry felt, which serves to guide the fibrous web through the extended press nip. Measurements should preferably be taken with the press at its maximum operating load.

[0011] If the pressure profile p(x) is integrated along the length of the extended press nip x, the resulting linear load LL is In the present example, according to Figure 3, the linear load LL corresponds to the triangular area under the line representing the pressure profile p(x). It is 1,560 kN / m. In this way, the quality of the measurement can be easily verified by comparing the linear load LL determined by the integration with the value previously defined as the linear load LL of the main press. It should be noted at this point that the linear load LL indicates the total force exerted by the main press per meter of width in the direction transverse to the machine, or orthogonal to the direction Petition 870250087490, dated 09 / 26 / 2025, page 36 / 64 5 / 14 of the movement of the fibrous mat.

[0012] Based on the measured pressure profile p(x), the weighted quadratic local pressure curve can now be easily determined using —-— * ü(%)2r, . LQMPar, the following formula: . This results in the curve shown in Figure 3, which intersects the straight line of the pressure profile p(x) at 10 MPa. The area under this curve corresponds to the weighted linear load WLL. It can be clearly observed in the graph of Figure 3 that local pressures below 10 MPa result in a smaller area, and pressures above 10 MPa, in a larger area compared to the triangular area, which represents the linear load LL. In the present example, the weighted line load WLL is 1,250 kN / m. This results in a line load ratio LLR as the quotient between the weighted line load WLL and the line load LL of 0.8, which is within the scope of the claimed invention, i.e., in the range: WLL0.69- ~ΊΓ ~1.52

[0013] In practice, the pressure profile curve p(x) does not necessarily have to be a straight line. Instead, there is a virtually inexhaustible variety of possible pressure profile curves p(x), even if the linear load LL, i.e., the area under the curve, remains constant. The shape of the pressure profile curve p(x) depends significantly on the geometric design of the pressing elements that form the extended pressing narrowing between them, in particular on the geometric design of any pressing shoe when using a shoe press.

[0014] Until now, only the linear load LL was used to characterize the pressure curve in an extended press nip. However, the inventors recognized that this parameter alone is not sufficient to accurately characterize the pressure curve and, therefore, also the dehydration behavior in the press nip. Petition 870250087490, dated 09 / 26 / 2025, page 37 / 64 6 / 14

[0015] As a certain average occurs through integration, for example, a constant pressure curve p = 10 MPa along the entire length of the press nip produces the same linear load LL as a pressure curve of p = 0 MPa in the first half and p = 20 MPa in the second half of the shoe length. However, the effect of these two pressure curves on dewatering and sheet structure is very different.

[0016] This difference is evidenced by the weighting in the weighted line load WLL. Thus, for the first case (p = 10 MPa), WLL = LL, or a line load ratio LLR of 1, and in the second case, WLL = 1.5 LL, that is, a line load ratio LLR of 1.5.

[0017] The relationship, therefore, allows pressure profiles with the same line load to be distinguished very easily and efficiently in their effect, without the need to analyze the pressure curve in detail. Generally, for the same line load, pressure profiles with strong pressure fluctuations and higher peak pressures tend to produce higher LLR values ​​than balanced profiles with average pressure values.

[0018] It is to the inventors' credit that they have discovered that a particularly efficient dewatering of the fibrous blanket can be achieved if the LLR line load ratio is at least 0.69 and at most 1.52, wherein the limit conditions being that the line load is at least 1,200 kN / m and that the press contact point has a length of at least 150 mm. If the extended contact point is provided by a shoe press, the shoe counter-roller should preferably have a diameter of less than 3,000 mm.

[0019] The linear load ratio (LLR) indirectly describes the geometric design of pressing elements, in particular of any pressing shoe. Since there is an uncontrollable number of different geometric designs, all resulting in a linear load ratio (LLR) between 0.69 and 1.52, the choice of the linear load ratio (LLR) is appropriate here to describe the inventive solution. It is important that the linear load ratio Petition 870250087490, dated 09 / 26 / 2025, page 38 / 64 7 / 14 LLR can be easily and unambiguously determined for a press arrangement with a fixed design of the pressing elements. It is also within the competence of a person skilled in the art, with knowledge of the present invention, to design the pressing elements in such a way that the desired linear load ratio LLR is achieved.

[0020] In known press arrangements, the linear load ratio (LLR) for the aforementioned limit conditions is always less than 0.69. In the press arrangement according to the invention, however, the pressing elements are designed in such a way that a linear load ratio (LLR) between 0.69 and 1.52 results, preferably between 0.71 and 1.35, particularly preferably between 0.73 and 1.14. It has been surprisingly demonstrated that such a linear load ratio (LLR) leads to more efficient dewatering of the fibrous mat, compared to known presses whose linear load ratio (LLR) is outside this range of values, in particular below 0.69.

[0021] An interesting subrange is the range for LLR values ​​less than one, that is, the range between 0.69 and 0.99, or 0.71 and 0.97 or 0.73 and 0.95.

[0022] The inventors also discovered that, with regard to the efficient dehydration of the fibrous mat, it is advantageous if the press arrangement further comprises a pre-press arranged upstream of the main press in the direction of movement of the fibrous mat, preferably immediately upstream. The pre-press serves to pre-compact and dehumidify the fibrous mat in such a way that it is not crushed, despite the high peak pressure in the main press. The press arrangement according to the invention may also comprise one or more additional presses, if necessary. In particular, another press may be installed upstream of the pre-press.

[0023] The press arrangement using a pre-press can be carried out in many different ways.

[0024] In particular, the prepress may preferably also have an extended press nip, in which the prepress is or may be designed. Petition 870250087490, dated 09 / 26 / 2025, p. 39 / 64 8 / 14 so that the LLR line load ratio of the prepress is less than 0.69.

[0025] Alternatively or additionally, the prepress may also have a CONVENTIONAL roller opening.

[0026] A very advantageous embodiment is a type of press marketed by the applicant under the name DuoCentri Nip Co Flex press. Two press nips are provided on a central roll. The first press nip is a conventional interroll opening that functions as a pre-press.

[0027] The main press is then represented by a shoe press, which is formed by a shoe press roll and the central roll as a counter-roll.

[0028] Another alternative embodiment consists of three shoe presses arranged one behind the other. The main press may be formed by the second or third of these shoe presses.

[0029] Regarding the line load with which the main press can be operated, this can also be greater than 1,200 kN / m, i.e., at least 1,300 kN / m, or even significantly higher. As mentioned above, however, there are practical limits to increasing the line load due to the increased risk of compression of the fibrous blanket, increasing the drive energy and increasing investment costs, especially for the design of a more massive base support.

[0030] Even though the peak pressure cannot be arbitrarily high for the reasons described above, it is preferably above 10 MPa, which, when using the LLR line load ratio according to the invention, leads to a significant increase in dry content, but without unduly compressing the fibrous blanket.

[0031] A preferred embodiment of the invention provides that the prepress is a shoe press, comprising a press shoe with a substantially curved concave surface and a shoe press sleeve rotatably mounted around the press shoe. Petition 870250087490, dated 09 / 26 / 2025, p. 40 / 64 9 / 14

[0032] It has been shown to be advantageous if the shoe press sleeve consists at least partially of polyurethane, which is formed by the reaction of a prepolymer and a crosslinking component, wherein the prepolymer is a reaction product of 1,4-phenylene diisocyanate (PPDI) and a polyol component containing at least one polyether polyol and / or at least one polycarbonate polyol, and wherein the crosslinking component contains a C2-14-Diol. It is further preferred that the polyol component of the prepolymer comprises polytetramethylene ether glycol (PTMEG) and at least one polycarbonate polyol. Alternatively or additionally, the crosslinking component may comprise polytetramethylene ether glycol (PTMEG) and / or at least one polycarbonate polyol.

[0033] A press sleeve with such a polyurethane layer has proven to be surprisingly durable, even at high peak pressures. Peak pressures significantly greater than 10 MPa do not pose a problem. At the same time, this polyurethane mixture is able to maintain good adhesion to the reinforcing yarns incorporated in it, even after many alternating load cycles under high peak pressures.

[0034] According to a further aspect, the present invention relates to a machine for producing a fibrous blanket, preferably a Packaging Testliner, comprising a press arrangement previously described according to the invention.

[0035] Furthermore, the invention relates to a method for pressing a fibrous blanket, in particular a packaging paper blanket, such as a Packaging Testliner, preferably using a press arrangement described above according to the invention, wherein the fibrous blanket is guided through a main press with an extended press nip of at least 150 mm in length, preferably at least 190 mm in length, wherein the main press is operated with a line load of at least 1,200 kN / m, preferably at least 1,300 kN / m, wherein the main press is designed such that a ratio Petition 870250087490, dated 09 / 26 / 2025, p. 41 / 64 10 / 14 of LLR line load of at least 0.69 and at most 1.52, wherein the LLR line load ratio is the quotient of a weighted WLL line load to the LL line load, where the weighted WLL line load is the result of an integration of a quadratic local pressure p(x)2 weighted with a weighting factor A over the press nip length x, wherein the weighting factor A is one divided by ten megapascals, and where the LL line load is the result of an integration of the local pressure p(x) over the press nip length x, so that the LLR line load ratio is given by the following formula: LLR = = = LL fp(x)dx fp(x)dx

[0036] The effects and advantages previously mentioned in relation to the press arrangement according to the invention also apply mutatis mutandis to the method according to the invention and vice versa.

[0037] Thus, in the method according to the invention, the LLR line load ratio is preferably at least 0.71 and at most 1.35, more preferably at least 0.73 and at most 1.14.

[0038] In addition, the fibrous mat is preferably guided through a pre-press arranged upstream of the main press in the direction of movement of the fibrous mat, preferably immediately upstream, where the pre-press may also have an extended press nip, where the pre-press may be designed so that the LLR line load ratio of the pre-press is less than 0.69.

[0039] The method and device according to the invention are particularly suitable when the fibrous web is a type of graphic paper or a type belonging to the Board & Packaging sector. It is particularly preferable that the fibrous web be a packaging paper web, such as Packaging Testliner. The types of tissue, however, are of minor or no importance.

[0040] The process according to the invention can be used in a way Petition 870250087490, dated 09 / 26 / 2025, p. 42 / 64 11 / 14 particularly efficient if the fibrous mat consists of at least 20% by weight, preferably at least 50% by weight, of OCC fibers. OCC is an abbreviation known in the state of the art and stands for "old corrugated containers". In other words, the press arrangement according to the invention and the method according to the invention are particularly suitable for efficiently dewatering fibrous mats that have a significant or even substantial proportion of used fibers, i.e., no new fibers. This is due to the high resistance of OCC fibers to high pressures. The remaining fibers of the fibrous mat to be pressed can be selected from mechanical or wood pulp, such as TMP, CTMP and / or PGW.

[0041] Press arrangements according to aspects of the present invention are also advantageous because they can be operated at high production speeds. Speeds exceeding 1000 m / min, especially exceeding 1200 m / min or even exceeding 1400 m / min, are possible. In this case, the installation of a pre-press is usually advantageous, as it generally allows for an increase in production speed.

[0042] The invention will be explained in more detail below with reference to an embodiment described with the aid of schematic figures:

[0043] Figure 1: a press arrangement according to the invention, comprising a main press and a pre-press;

[0044] Figure 2: an enlarged and detailed view of the main press of the press arrangement shown in Figure 1,

[0045] Figure 3: an illustrative pressure curve on the extended press nip of the main press.

[0046] Figure 1 shows a very schematic representation of a press arrangement according to the invention, comprising a main press 1 and a pre-press 11 arranged directly in front of it in the direction of movement BR of a fibrous blanket 8. In this embodiment, Petition 870250087490, dated 09 / 26 / 2025, page 43 / 64 12 / 14 Both the main press 1 and the pre-press 11 are designed as shoe presses and therefore each has an extended press nip. Alternatively, however, the pre-press 11 could not have an extended press nip and / or the pre-press 11 and the main press 1 could share a common central roll. The central roll would then be a press element through which both the extended press nip of the pre-press 11 and the extended press nip of the main press 1 would be formed.

[0047] Figure 2 shows an enlarged and detailed view of the main press 1, which is of particular importance according to the invention. This was designed to operate with a line load LL of at least 1,200 kN / m, preferably at least 1,300 kN / m. The extended press nip 7 of the main press 1 is provided by two press elements, namely, a press shoe roll 2 and a counter-roller 3. The press shoe roll 2 comprises a press shoe 5, which is supported on a stationary yoke 4, and a press shoe sleeve 6, which is rotatably arranged around the press shoe 5. Preferably, the fibrous blanket 8 is guided in a sandwich-like manner between two pressing felts 9 through the extended press nip 7. The press shoe 5 has a substantially concave surface over which the press shoe sleeve 6 runs, while the press shoe 5 presses it with a high pressing force F towards the counter-roller 3.The geometric design of the pressing elements, in particular the press shoe 5, is selected so that it results in a linear load ratio (LLR) of at least 0.69 and at most 1.52.

[0048] The pressing force F is preferably selected to be so large that the peak pressure acting on the fibrous mat 8 at the extended press nip point 7 is at least 10 MPa. The length of the extended press nip point of the main press 1 is at least 150 mm, preferably at least 190 mm.

[0049] It has proven to be particularly advantageous at such peak pressures Petition 870250087490, dated 09 / 26 / 2025, pp. 44 / 64 13 / 14 if the shoe press sleeve 6 consists at least partially of polyurethane, which is formed by the reaction of a prepolymer and a crosslinking component, wherein the prepolymer is a reaction product of 1,4-phenylene diisocyanate (PPDI) and a polyol component containing at least one polyether polyol and / or at least one polycarbonate polyol, and wherein the crosslinking component contains a C2-14-Diol. For example, the shoe press sleeve 6 may have a reinforcing structure made of yarns embedded in the polyurethane layer, wherein the polyurethane layer prepolymer consists of 50% by weight of a mixture of 1,4-phenylene diisocyanate (PPDI) and C5-6-polycarbonatediol and 50% by weight of a mixture of 1,4-phenylene diisocyanate (PPDI) and polytetramethylene ether glycol (PTMEG), and wherein the crosslinker comprises polytetramethylene ether glycol (PTMEG) and 1,6-hexanediol or is preferably formed substantially from the same.

[0050] The pre-press 11 shown schematically in Figure 1 can and preferably is designed differently from the main press 1. In particular, unlike the main press 1, it can be designed so that the LLR line load ratio of the pre-press 11 is less than 0.69. The pre-press 11 serves in the press arrangement in particular to sufficiently pre-consolidate the fibrous mat 8 for passage through the main press 1, so that it is not excessively compressed, despite a relatively high peak pressure in the second press 1.

[0051] The fibrous mat 8 is preferably used to produce a paper mat for packaging or is a paper mat for packaging. In addition, the fibrous mat preferably consists of at least 20% by weight, more preferably at least 50% by weight, of OCC fibers, which are characterized by particularly high strength, even at high peak pressures.

[0052] The press arrangement 1 according to the invention could theoretically also comprise more presses than just the pre-press 11 Petition 870250087490, dated 09 / 26 / 2025, page 45 / 64 14 / 14 and the main press 1. However, the main press 1 is preferably the last press in the press arrangement, i.e., the last press before the fibrous mat 8 is transferred to a drying section downstream of the press arrangement.

[0053] List of Reference Numerals main press shoe press roller counter-roller stationary yoke press shoe press sleeve extended press nip fibrous blanket press felt press arrangement Pre-press BR direction of movement F pressure force Petition 870250087490, dated 09 / 26 / 2025, pp. 46 / 64

Claims

1 / 4 CLAIMS 1. Press arrangement (10) for pressing a fibrous blanket (8), in particular a packaging paper blanket, comprising a main press (1) with an extended press nip (7), wherein the press nip (7) has a length of at least 150 mm, preferably at least 190 mm, characterized in that the main press (1) is designed in such a way that, when operated with a line load LL of at least 1.200 kN / m, results in a line load ratio LLR of at least 0.69 and at most 1.52, wherein the line load ratio LLR is the quotient of a weighted line load WLL to the line load LL, wherein the weighted line load WLL is the result of an integration of the quadratic local pressure p(x)2 weighted with a weighting factor A over the press nip length x, wherein the weighting factor A is one divided by ten megapascals, and wherein the line load LL is the result of an integration of the local pressure p(x) over the press nip length x, so that the following formula results for the line load ratio LLR: LLR = = = LL fp(x)dx fp(x)dx wherein x is the unit mm and p is the unit MPa, and wherein the pressure on the press nip (7) is constant in the transverse direction of the machine.

2. Press arrangement (10), according to claim 1, characterized in that the LLR line load ratio is at least 0.71 and at most 1.35, preferably at least 0.73 and at most 1.

14.

3. Press arrangement (10), according to claim 1 or 2, characterized in that the press arrangement (10) further comprises Petition 870250087490, dated 09 / 26 / 2025, page 48 / 64 2 / 4 a pre-press (11) arranged upstream of the main press (1) in the direction of movement of the fibrous mat (8), preferably directly upstream.

4. Press arrangement (10), according to claim 3, characterized in that the pre-press (11) also has an extended press nip, wherein the pre-press (11) is designed such that the LLR line load ratio of the pre-press is less than 0.

69.

5. Press arrangement (10), according to any of the preceding claims, characterized in that the main press (1) is designed to be operated with a line load LL of at least 1,300 kN / m.

6. Press arrangement (10), according to any of the preceding claims, characterized in that the main press (1) is a shoe press, comprising a press shoe (5) with a substantially curved concave surface and a shoe press sleeve (6) rotatably mounted around the press shoe (5).

7. Press arrangement (10), according to claim 6, characterized in that the shoe press sleeve (10) consists at least partially of polyurethane, which is formed by the reaction of a prepolymer and a crosslinking component, wherein the prepolymer is a reaction product of 1,4-phenylene diisocyanate (PPDI) and a polyol component containing at least one polyether polyol and / or at least one polycarbonate polyol, and wherein the crosslinking component contains a C2-14-Diol.

8. Press arrangement (10), according to claim 7, characterized in that the polyol component of the prepolymer comprises polytetramethylene ether glycol (PTMEG) and at least one polycarbonate polyol.

9. Press arrangement (10), according to claim 7 or 8, characterized in that the crosslinking component comprises Petition 870250087490, dated 09 / 26 / 2025, page 49 / 64 3 / 4 polytetramethylene ether glycol (PTMEG) and / or at least one polycarbonate polyol.

10. Machine for producing a fibrous blanket (8), preferably a Packaging Testliner, characterized in that it comprises a press arrangement (10), as defined in any of the preceding claims.

11. Method for pressing a fibrous blanket (8), in particular a packaging paper blanket, as a Packaging Testliner, preferably using a press arrangement (10), as defined in any one of claims 1 to 9, wherein the fibrous blanket (8) is guided through a main press (1) with an extended press nip (7) of at least 150 mm in length, preferably at least 190 mm in length, characterized in that the main press (1) is operated with a line load LL of at least 1,200 kN / m, preferably at least 1.300 kN / m, wherein the main press (1) is designed such that a line load ratio LLR of at least 0.69 and at most 1.52 is obtained, wherein the line load ratio LLR is the quotient of a weighted line load WLL to the line load LL, wherein the weighted line load WLL is the result of an integration of a quadratic local pressure p(x)2 weighted with a weighting factor A over the press nip length x, wherein the weighting factor A is one divided by ten megapascals, and wherein the line load LL is the result of an integration of the local pressure p(x) over the press nip length x, so that the following formula results for the line load ratio LLR. LLR = ^ = = ii fp(x)dx fp(x)dx where x is the unit mm and p is the unit MPa, and where the pressure in the press nip (7) is constant in the transverse direction of the machine.

12. Method according to claim 11, characterized in that the LLR line load ratio is at least 0.71 and at most 1.35, preferably at least 0.73 and at most 1.

14.

13. Method according to claim 11 or 12, characterized in that the fibrous mat (8) is further guided through a pre-press (11) disposed upstream of the main press (1) in the direction of displacement of the fibrous mat (8), preferably directly upstream.

14. Method, according to any one of claims 11 to 13, characterized in that the method is carried out at a speed of at least 1,000 m / min, preferably at least 1,200 m / min, in particular more than 1,400 m / min.

15. Method, according to any one of claims 11 to 14, characterized in that the fibrous mat (8) consists of at least 20% by weight, preferably at least 50% by weight of OCC fibers. Petition 870250087490, dated 09 / 26 / 2025, pp. 51 / 64

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