Method for producing containerboard

Abstract

The invention relates to a method for producing containerboard. The method comprises providing an aqueous slurry of a cellulose material, feeding said aqueous slurry to a forming section and forming a web from the said aqueous slurry, compacting and further dewatering / drying the web by means of a press section, and further drying the web by means of a drying section. Said cellulose material is provided comprising 90 wt.% to 100 wt.% of a semi-chemical pulp. The forming section is provided comprising a breast roll shaker assigned to the breast roll and configured for oscillating the breast roll in a cross direction. The web is dried and compacted to a containerboard web with a final water content of 2 wt.% to 14 wt.% and a final Gurley porosity measured according to ISO 5636-5:2013 of 80 s or more.

Description

[0001] The invention relates to a method for producing containerboard.

[0002] The term containerboard in general specifies a type of paperboard which is used in paper packaging applications, more specifically is used for manufacturing corrugated board. Containerboard hereby is often further processed to corrugated medium by means of so-called corrugators and is then used as fluting in corrugated board. Containerboard however may also be used as so-called linerboard in corrugated board, thus as flat sheet that usually covers the fluting of corrugated board on one or both sides of the fluting.

[0003] Containerboard generally can be made from virgin cellulose material or from recycled, cellulose-based material. Virgin cellulose material may be made / derived from hardwood or softwood, such that long-fiber (usually made from softwood) and / or short-fiber (usually derived from hardwood) cellulose material may in principle be used. Virgin cellulose material used for containerboard may also be unbleached or bleached. Nowadays, semichemical processes are being used more and more frequently for producing virgin cellulose material, since semi-chemical pulping is more sustainable and less chemical and energy demanding than other pulping methods, such as Kraft pulping for example. In semichemical pulping, short fiber material derived from hardwood is by far the most commonly used type of cellulose material.

[0004] Since containerboard is generally used in paper packaging applications, the main requirement for containerboard is to exhibit good mechanical stability, in particular good resistance to deformation forces to provide protection for the product(s) packed within a corrugated board, such as a box. Thereby it is highly desirable, that corrugated board exhibits high mechanical stability and deformation resistance in all directions. In other words, containerboard is required to best possible withstand deformation forces from all directions and thus provide mechanical stability regardless of the direction from which such deforming force acts. In this context, it is however also desirable for containerboard to provide sufficient mechanical stability with low material use.

[0005] In the field of containerboard making, a continuing need for making containerboard with high, uniform mechanical stability and simultaneously low material use therefore exists.

[0006] The objective of the invention thus was to address such need, and to provide a method for producing containerboard with high, uniform mechanical stability and resistance to deformation forces from all directions, and simultaneously low usage of cellulose material to achieve said high, uniform mechanical stability.

[0007] This objective is achieved by providing a method as specified in the corresponding claims.

[0008] The method for producing containerboard, comprises providing an aqueous slurry of a cellulose material, said aqueous slurry consisting of 99 wt.% to 99,9 wt.% water and 0,1 wt.% to 1 wt.% of the cellulose material, feeding said aqueous slurry to a forming section, wherein the forming section is provided comprising a headbox, a circulating Fourdrinier wire and a breast roll supporting the Fourdrinier wire at or near the headbox, and forming a web from the said aqueous slurry by forming the aqueous slurry into a sheet-like structure and dewatering the aqueous slurry by means of the forming section, compacting and further dewatering / drying the web by means of a press section, and further drying the web by means of a drying section.

[0009] Hereby, the said cellulose material is provided comprising 90 wt.% to 100 wt.% of a semi-chemical pulp. In addition, the forming section is provided comprising a breast roll shaker assigned to the breast roll and configured for oscillating the breast roll in a cross direction. Overall, the web is dried and compacted to a containerboard web with a final water content of 2 wt.% to 14 wt.%, in particular 2 wt.% to 10 wt.%, and a final Gurley porosity measured according to ISO 5636-5:2013 of 80 s or more.

[0010] The semichemical pulp of the cellulose material may for example comprise or consist of short cellulose fibers having a fiber length of 0,7 mm to 1,6 mm. The semichemical pulp in general may be made from hardwood material. The web formed by means of the forming section may also be referred to as paper web. The web may for example be dried and compacted to a final Gurley porosity measured according to ISO 5636-5:2013 of 80 s to 250 s.

[0011] The cellulose material provided for the aqueous slurry may, apart from the semichemical pulp, comprise up to 10 wt.% of other substances, such as substances commonly known and used in paper making. Such other substances may for example be additives commonly used in the art of paper making, but also other types of pulp than the semichemical pulp, and / or for example polymeric materials. Typical additives may for example comprise processing agents, pH control agents, sizing and wet or dry strength agents, fillers like clay and / or calcium carbonate and so on.

[0012] While the so-called breast roll shakers are in principle known in the art of paper making, such breast roll shakers have been used in the past solely in connection with the production of paper products predominantly made of long fiber cellulose material. Such processes are for example disclosed in EP 3 224 409 B1 and WO 2019 / 136250 A1. In connection with the production of paper products predominantly made of short fiber cellulose material, such breast roll shakers have not been used in the past according to the knowledge of the inventors, because of the general believe, that such breast roll shakers would inhibit / reduce inter-fiber bonding when using short fiber cellulose material, thus causing considerable losses in mechanical strength of paper made from such short fiber material, for example leading to papers with too high porosity, and also causing problems for the paper making process itself, for example by causing more non-uniform fiber distribution and causing clumping.

[0013] Surprisingly however, the inventors found that the oscillation of the breast roll by means of the breast roll shaker is feasible in connection with the processing of the cellulose material as specified above, in particular is feasible and advantageous when using a semichemical pulp. Containerboard in this context in general is produced with higher grammages as compared to other paper types. The grammage of a typical containerboard can for example be set to 70 g / m 2< to 300 g / m 2< . The semichemical pulp can in particular be produced by means of the neutral sulfite semi-chemical pulp process (NSSC) and may thus be a so-called NSSC pulp.

[0014] By means of shaking / oscillating the breast roll, the dewatering capacity per time unit can be increased considerably in the initial stage of web formation. This is advantageous in particular in context with the production of containerboard, because of the high grammage of such containerboard and the therefore high water content of the initial, aqueous slurry. The highly efficient, initial dewatering facilitates the following dewatering / drying steps in the press section and the drying section, such that these drying steps after the initial dewatering in the forming section may be conducted with less energy consumption. In particular, the drying in the drying section involves heated drying cylinders, thus having a high energy consumption per unit amount of water removed. The initial shaking / oscillating of the breast roll thus allows for a more energy efficient production of containerboard in general. This is especially useful in context with containerboard production, since comparably thick webs with a high amount of water are typically formed for containerboard production, as containerboards are produced with comparably high grammages as already outlined above. Because of the high thickness web initially formed for containerboard production, a building up turbulences in such thick webs is actually inhibited as compared to webs having lower thickness, thus causing comparably even lower water removal rates. The shaking of the breast roll and the artificial turbulences generated thereby in the sheet-like structure initially formed from the aqueous slurry helps removing a higher amount of water per time unit out of the web and removed through the Fourdrinier wire / fabric. Overall, the faster water removal rate induced by the oscillation of the breast roll allows for higher throughput, respectively higher production rates.

[0015] The oscillation of the breast roll also brings about a more homogenous distribution of fiber orientation, such that the fibers are not predominantly oriented in a machine direction (MD). The machine direction (MD) thereby designates the direction of material transport in a paper machine as the person of ordinary skill in the art of paper making knows. The oscillation of the breast roll by means of the breast roll shaker leads to a more homogenous distribution of fiber orientation, in particular a higher percentage of cellulose fibers are being oriented in the cross direction (CD), which is the direction perpendicular to the machine direction (MD) as is also commonly known. This in turn causes more homogenous and direction independent mechanical properties in the finished containerboard, enabling the production of containerboards with enhanced mechanical stability and helping impede any direction dependent, mechanical weaknesses in a containerboard. In particular, mechanical strength in the cross direction (CD) especially important for containerboards can be enhanced by means of the oscillation of the breast roll.

[0016] For example, in an embodiment of the method, the containerboard web may be produced having a tensile strength measured according to ISO 1924-2:2008 in the cross direction (CD) which is 35 % to 50 % lower than the tensile strength in a machine direction (MD).

[0017] The containerboard web may in particular be produced having a tensile strength measured according to ISO 1924-2:2008 in the cross direction (CD) of 5 N / mm 2< to 10 N / mm 2< , preferably 6 N / mm 2< to 9,8 N / mm 2< .

[0018] In another embodiment, the containerboard web may be produced having a tensile stiffness measured according to ISO 1924-3:2005 in the cross direction (CD) which is 30 % to 50 % lower than the tensile stiffness in a machine direction (MD).

[0019] For example, the containerboard web may be produced having a tensile stiffness measured according to ISO 1924-3:2005 in the cross direction (CD) of 400 kN / m to 900 kN / m.

[0020] In yet another embodiment of the method the containerboard web is produced having a compressive strength measured by means of a short-span compression test (SCT) according to ISO 9895:2008 in the cross direction (CD) which is 50 % to 65 % lower than the compressive strength in a machine direction (MD).

[0021] The compression strength according to ISO 9895:2008 often is referred to as SCT value. The containerboard web may for example be produced having a compressive strength respectively SCT value according to ISO 9895:2008 in the cross direction (CD) of 4,8 kN / m to 11 kN / m. The compression strength in cross direction (CD) thereby is parameter with extraordinary relevance for containerboard applications, in particular for flutings in corrugated boards, to which flutings containerboard webs are commonly processed.

[0022] When the containerboard web is further processed into a corrugated fluting, such fluting may for example have a CMT (Corrugated Medium Test) value according to EN ISO 7263-2:2019 in the range of 230 N to 580 N.

[0023] The above features of preferred embodiments of the method all allow for production of containerboard with high mechanical stability and deformation resistance against deforming forces from multiple directions. In particular, the mechanical strength and stability in the cross direction (CD) can be vastly improved as compared to prior methods for containerboard production.

[0024] In a preferred embodiment of the method, the press section may be provided comprising at least one shoe press and the web may be compacted with the at least one shoe press.

[0025] The inventors found that one or more shoe press(es) is or are particularly useful for dewatering / drying and compacting a web with comparatively homogenous fiber orientation, wherein only one shoe press, but also two or even more shoe presses may be used to compact the web within the press section. It appears that a shoe press is essentially efficient in compacting the web formed and dewatered in the forming section, probably because of effectively inducing inter-fiber bonding not only in the machine direction (MD), but also in the cross direction (CD). This effect may be attributable to the relatively high residence time in the wide nip of a shoe press and / or the comparatively high nip pressure applicable to the web by a shoe press. The exact design of a shoe press doesn't seem to be of particular importance, such that any design having a stationary concave shoe in conjunction with a moving roll or belt, so the essential design elements of a shoe press, may be used. The high residence time in the wide nip of a shoe press also allows for a higher amount of water to be removed from the web, thus further enhancing the energy efficiency of the method by allowing for the use of less energy input in the following drying section.

[0026] In particular, the web may be compacted by means of the at least one shoe press with a total or cumulative nip pressure of 15 bar to 80 bar. In addition, the web may be compacted in the press section with a total line load of 650 kN / m to 2050 kN / m.

[0027] In another embodiment, the web may be compacted with the at least one shoe press at a nip width of 200 mm to 350 mm.

[0028] The above parameters have proven to be especially useful for dewatering and compacting the web, wherein the web leaving the shoe press(es) may then easily and reliably be further processed and dried with high efficiency.

[0029] In a preferred embodiment of the method, the said breast roll may be oscillated by means of said breast roll shaker at a frequency of 3 Hz to 10 Hz.

[0030] The breast roll may be oscillated by means of said breast roll shaker with a stroke / amplitude of 12 mm to 34 mm.

[0031] The above oscillation parameters for the breast roll shakers were found to be very suitable to achieve a good, homogenous fiber alignment as well as efficient dewatering. The oscillation parameters within the ranges given above on the one hand were found to be sufficient to induce high enough fiber alignment in the cross direction (CD) in the relatively thick webs formed for the production of containerboard, without causing excessive vibrations potentially leading to uneven fiber distribution and clumping within the forming web. On the other hand, the above ranges of oscillation parameters were also found to be especially suitable for running the corresponding machinery parts, in particular the breast roll and the Fourdrinier wire in a secure manner, without inducing too much stress upon those machinery parts.

[0032] More preferably, the breast roll may be oscillated by means of said breast roll shaker at a frequency of 6 Hz to 9 Hz.

[0033] The breast roll may preferably be oscillated by means of said breast roll shaker with a stroke / amplitude of 18 mm to 22 mm.

[0034] In another embodiment of the method, the aqueous slurry may be fed to the Fourdrinier wire at a jet-to-wire speed ratio of 0,95 to 0,99.

[0035] It was found, that such slightly higher wire speed than jet speed is particularly suitable for use in combination with oscillating the breast roll by means of the breast roll shaker. Carrying out the method within the jet-to-wire speed ratio range given above is especially useful for bringing about a good balance of fiber orientation within the web formed on the Fourdrinier wire, thereby gaining enough, but not excessive fiber orientation in the cross direction (CD).

[0036] To provide a better understanding, the invention is described in more detail in the following based on exemplary embodiments shown in the figures. These are merely preferred, exemplary embodiments however, and those having ordinary skill in the art will appreciate that the invention also can be carried out in technical meaningful ways deviating from these exemplary embodiments. Such technical possible deviations from the exemplary embodiments lie within the reach of a person skilled in the technical field of paper making, and various modifications of the exemplary embodiments can be chosen and executed by such person of ordinary skill in the art to meet actual requirements for the paper liner web to be produced, such as application and / or quality requirements for example.

[0037] The figures each show highly simplified, schematic drawings illustrating the following: Fig. 1A simple chart showing the sequence of working steps of the method; Fig. 2An exemplary embodiment of a forming section suitable for carrying out the method, viewed from the top and shown in part; Fig. 3An exemplary embodiment of a shoe press suitable for the method, shown in a sectional view; Fig. 4An exemplary embodiment of a drying section, shown in simplified manner in part and viewed from the side.

[0038] Introductory, it should be pointed out, that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc., relate to the drawing specifically being described and can be transposed in terms of meaning to a new position when another position is being described.

[0039] As is generally known in the art of paper and board making and can be depicted from Fig. 1, the method for producing containerboard comprises a step of providing an aqueous slurry 1 of a cellulose material, which is subsequently formed into a web and dewatered / dried by means of multiple, subsequent sections of a paper machine. Said aqueous slurry 1 provided thereby consists of 99 wt.% to 99,9 wt.% water and 0,1 wt.% to 1 wt.% of the cellulose material.

[0040] Said cellulose material of the aqueous slurry 1 is provided comprising 90 wt.% to 100 wt.% of a semichemical pulp. The semichemical pulp may for example comprise or consist of short cellulose fibers with a fiber length of 0,7 mm to 1,6 mm. The semichemical pulp may be made from hardwood material. The semichemical pulp can be produced according to any semichemical pulping method, thus using a mild chemical treatment as compared to Kraft pulping for example, and often followed by refining as is commonly known in the art of pulp making. In particular, the semichemical pulp can be made by means of the so-called neutral sulfite semi-chemical pulp process (NSSC), and in that case the semichemical pulp may be referred to or designated as NSSC (short fiber) pulp. In general, the cellulose material of the semichemical pulp provided for the method can be made from short fiber hardwood cellulose material.

[0041] The cellulose material of the aqueous slurry may, apart from the semichemical pulp, comprise up to 10 wt.% of other substances, such as substances commonly known and used in paper making. Such other substances may for example be additives commonly used in the art of paper making, but also other types of pulp than the semichemical pulp, and / or for example polymeric materials. Typical additives may for example comprise processing agents, pH control agents, sizing and wet or dry strength agents, fillers like clay and / or calcium carbonate and so on.

[0042] As depicted in Fig. 1, the method then comprises feeding aqueous slurry 1 to a forming section 2, which forming section 2 is shown in part and viewed from the top in more detail in Fig. 2. Referring to Fig. 2, the forming section 2 is provided comprising a headbox 3, a circulating Fourdrinier wire 4 and a breast roll 5 supporting the Fourdrinier wire 4 at or near the headbox 3. As also is shown in Fig. 2, a web 6 is formed from the said aqueous slurry 1 by forming the aqueous slurry 1 into a sheet-like structure and dewatering the aqueous slurry 1 by means of the forming section 2. As is commonly known in the art, the web 6 may thereby initially be formed by feeding the aqueous slurry 1 by feeding the aqueous slurry 1 via a slot / jet nozzle 7 of the headbox 3 onto the Fourdrinier wire 4 and allowing and / or forcing water to be drawn out of the thus formed web 6 of the aqueous slurry 1 through the Fourdrinier wire 4.

[0043] Within the method, the aqueous slurry 1 may preferably be fed onto the Fourdrinier wire 4 at a jet-to-wire speed ratio of 0,95 to 0,99.

[0044] The web 6 is transported by or on the Fourdrinier wire 4 in a direction commonly referred to as machine direction 8 (MD) as shown in Fig. 2.

[0045] As also is shown in Fig. 2, for the method the forming section 2 is provided comprising a breast roll shaker 9 assigned to the breast roll 5. This breast roll shaker 9 thereby is configured for oscillating the breast roll 5 in a direction commonly referred to as cross direction 10 (CD) in paper making. As known in the art, said cross direction 10 (CD) generally is perpendicular to the machine direction 8, as depicted by the double-arrow in Fig. 2.

[0046] Within the method, the breast roll 5 may preferably be oscillated by means of said breast roll shaker 9 at a frequency of 3 Hz to 10 Hz. In particular, the breast roll 5 may be oscillated by means of said breast roll shaker 9 at a frequency of 3 Hz to 10 Hz.

[0047] The breast roll 5 may preferably be oscillated by means of said breast roll shaker 9 with a stroke / amplitude of 12 mm to 34 mm, in particular may be oscillated with a stroke / amplitude of 18 mm to 22 mm.

[0048] As sketched in Fig.1, after having passed the forming section 2, the web 6 is then transferred to a press section 11. The method thus comprises a compacting and further dewatering / drying of the web 6 by means of said press section 11.

[0049] The press section 11 may be provided / configured in any way known from paper machines and suitable for needs for producing a particular containerboard. The press section 11 of a paper machine typically may comprise a number of rolls pressing against each other, normally arranged in pairs, such that the web 6 is guided through nips formed by the rolls pressing against each other. Commonly, the web 6 is guided through these nips supported / aided by felts that absorb the water pressed out of the web 6 within the nips. However, other types of pressing equipment may also be included in a press section 11 suitable for the method. Such configurations of press sections 11 are commonly known in the art and thus need not be described or shown in detail.

[0050] In a particular preferred embodiment of the method, the press section 11 is provided comprising at least one shoe press 12 and the web 6 is compacted with the at least one shoe press 12. Numerous types of shoe presses 12 have already developed and the particular configuration of a shoe press is not particularly relevant for the method. Within the method, only one shoe press, but also two or even more shoe presses may be used to compact the web within the press section.

[0051] One example of a shoe press 12 is shown in Fig. 3. As can be seen from Fig. 3, the nip 13 of a shoe press 12 comprises a stationary shoe 14 loaded against a press roll 15. In other words, within a shoe press 12 a stationary and usually concave shoe 14 in principle replaces a roller, usually the bottom roller of a conventional pair of rollers forming a nip. Typically, a felt 16 may be used to transport the water pressed out of the web 6 by means of the shoe press 12. As shown in the exemplary embodiment in Fig. 3, a belt 17 or sleeve may form a shell that runs between the mechanical press and the felt 16, wherein typically oil may be supplied on the inside of the belt to act as load transfer medium and to act as lubricant between the stationary shoe and the moving belt 17. Fig. 3 however merely shows an exemplary embodiment of a shoe press and other configurations, such as open belt configurations or configurations with other types of shoes are also possible.

[0052] Preferably, the web 6 may be compacted by means of the at least one shoe press 12 with a total or cumulative nip pressure of 15 bar to 80 bar. In addition, the web may be compacted in the press section with a total line load of 650 kN / m to 2050 kN / m.

[0053] As illustrated in Fig. 3, the web 6 may be compacted with the at least one shoe press 12 at a nip width 18 of 200 mm to 350 mm.

[0054] Referring back to Fig. 1 again, the compacted and dewatered web 6 is then transferred to a drying section 19. The method thus comprises further drying the web 6 by means of such drying section 19.

[0055] A typical example for a suitable drying section 19 is shown in sideview in Fig. 4. A drying section 19 commonly comprises numerous heated dryer cylinders 20 which are contacted with the web 6 pre-dried and compacted in the previous forming section 2 and press section 11. Typically, internally steam-heated dryer cylinders 20 are used for the purpose of drying the web 6 to a finalized containerboard web 21 with a final, desired water content, as is commonly known in the art and shown in Fig 4. The containerboard web 21 leaving the drying section 19 may then be further be processed, for example rolled up onto transport rollers or cut into pieces with suitable sizes such as to make liners or flutings for corrugated board applications, e.g. packaging boxes and son on.

[0056] Within the method, the web 6 is dried and compacted to a containerboard web 21 with a final water content of 2 wt.% to 14 wt.%, in particular 2 wt.% to 10 wt.%, and a final Gurley porosity measured according to ISO 5636-5:2013 of 80 s or more. For example, the web may be dried and compacted to a final Gurley porosity measured according to ISO 5636-5:2013 of 80 s to 250 s.

[0057] In an embodiment of the method, the containerboard web 21 may be produced having a tensile strength measured according to ISO 1924-2:2008 in the cross direction 10 which is 35 % to 50 % lower than the tensile strength in the machine direction 8. The containerboard web 21 may for example be produced having a tensile strength measured according to ISO 1924-2:2008 in the cross direction 10 of 5 N / mm 2< to 10 N / mm 2< , in particular 6 N / mm 2< to 9,8 N / mm 2< .

[0058] In another embodiment of the method, the containerboard web 21 may be produced having a tensile stiffness measured according to ISO 1924-3:2005 in the cross direction 10 which is 30 % to 50 % lower than the tensile stiffness in the machine direction 8. For example, the containerboard web 21 may be produced having a tensile stiffness measured according to ISO 1924-3:2005 in the cross direction 10 of 400 kN / m to 900 kN / m.

[0059] In yet another embodiment of the method, the containerboard web 21 may be produced having a compressive strength measured by means of a short-span compression test according to ISO 9895:2008 in the cross direction 10 which is 50 % to 65 % lower than the compressive strength in a machine direction 8. For example, the containerboard web 21 may be produced having a compressive strength measured by means of a short-span compression test according to ISO 9895:2008 in the cross direction 10 of 4,8 kN / m to 11 kN / m. The compression strength according to ISO 9895:2008 may hereby also designated as SCT value.

[0060] In general, and according to actual needs and desires for a specific containerboard, the above-described sections 2, 11, 19 may comprise further elements, parts and devices not explicitly shown in Figures 2 to 4 or mentioned otherwise, which are commonly known in the art of paper making, such as surface conditioning and modifying devices and so on. Also, additional sections in addition to the forming section 2, press section 11 and drying section 19 may be used within a paper machine for producing specific containerboard. As also commonly known, for the method of producing containerboard the sections 2, 11, 19 and probable additional sections are typically configured to produce a containerboard / paper web with high grammage as compared to many other paper types, such as for example containerboard (web) with a grammage of 70 g / m 2< to 300 g / m 2< .

[0061] The embodiments illustrated as examples represent possible variants and it should be pointed out at this stage that the invention is not specifically limited to the variants specifically illustrated, and instead the individual variants may be used in different combinations with one another and these possible variations lie within the reach of the person skilled in this technical field given the disclosed technical teaching.

[0062] The protective scope is defined by the claims. However, reference may be made to the description and drawings with a view to interpreting the claims. Individual features or combinations of features from the different examples of embodiments described and illustrated may also be construed as independent embodiments of the solutions proposed by the invention.

[0063] The objective underlying the individual solutions proposed by the invention may be found in the description.

[0064] For the sake of good order, finally, it should be pointed out that, in order to provide a clearer understanding of the structure, elements are illustrated to a certain extent out of scale and / or on an enlarged scale and / or on a reduced scale.List of references

[0065] 1Aqueous slurry 2Forming section 3Headbox 4Fourdrinier wire 5Breast roll 6Web 7Jet nozzle 8Machine direction 9Breast roll shaker 10Cross direction 11Press section 12Shoe press 13Nip 14Shoe 15Press roll 16Felt 17Belt 18Nip width 19Drying section 20Dryer cylinder 21Container web

Claims

1. Method for producing containerboard, comprising - providing an aqueous slurry (1) of a cellulose material, said aqueous slurry (1) consisting of 99 wt.% to 99,9 wt.% water and 0,1 wt.% to 1 wt.% of the cellulose material, - feeding said aqueous slurry (1) to a forming section (2), wherein the forming section (2) is provided comprising a headbox (3), a circulating Fourdrinier wire (4) and a breast roll (5) supporting the Fourdrinier wire (4) at the headbox (3), and forming a web (6) from the said aqueous slurry (1) by forming the aqueous slurry (1) into a sheet-like structure and dewatering the aqueous slurry (1) by means of the forming section (2), - compacting and further dewatering / drying the web (6) by means of a press section (11), - further drying the web (6) by means of a drying section (19), wherein, said cellulose material is provided comprising 90 wt.% to 100 wt.% of a semichemical pulp, wherein the forming section (2) is provided comprising a breast roll shaker (9) assigned to the breast roll (5) and configured for oscillating the breast roll (5) in a cross direction (10), and wherein the web (6) is dried and compacted to a containerboard web (21) with a final water content of 2 wt.% to 14 wt.% and a final Gurley porosity measured according to ISO 5636-5:2013 of 80 s or more.

2. Method according to claim 1, characterized in that the containerboard web (21) is produced having a tensile strength measured according to ISO 1924-2:2008 in the cross direction (10) which is 35 % to 50 % lower than the tensile strength in a machine direction (8).

3. Method according to claim 1 or 2, characterized in that the containerboard web (21) is produced having a tensile stiffness measured according to ISO 1924-3:2005 in the cross direction (10) which is 30 % to 50 % lower than the tensile stiffness in a machine direction (8).

4. Method according to any one of claims 1 to 3, characterized in that the containerboard web (21) is produced having a compressive strength measured by means of a short-span compression test according to ISO 9895:2008 in the cross direction (10) which is 50 % to 65 % lower than the compressive strength in a machine direction (8).

5. Method according to any one of claims 1 to 4, characterized in that the press section (11) is provided comprising at least one shoe press (12) and the web (6) is compacted with the at least one shoe press (12).

6. Method according to claim 5, characterized in that the web (6) is compacted by means of the at least one shoe press (12) with a total nip pressure of 15 bar to 80 bar.

7. Method according to claim 5 or 6, characterized in that the web (6) is compacted with the at least one shoe press (12) at a nip width (18) of 200 mm to 350 mm.

8. Method according to any one of claims 1 to 7, characterized in that said breast roll (5) is oscillated by means of said breast roll shaker (9) at a frequency of 3 Hz to 10 Hz.

9. Method according to any one of claims 1 to 8, characterized in that said breast roll (5) is oscillated by means of said breast roll shaker (9) with a stroke of 12 mm to 34 mm.

10. Method according to any one of claims 1 to 9, characterized in that said aqueous slurry (1) is fed to the Fourdrinier wire (4) at a jet-to-wire speed ratio of 0,95 to 0,99.

Images