Flutting or liner containing NSSC pulp

Abstract

The present invention relates to a flute or liner for corrugated board comprising neutral sulfite semi-chemical (NSSC) pulp, the NSSC pulp having an ash content of less than 1.8 wt.% as determined according to ISO standard 1762: 2019. The present invention further relates to a corrugated board comprising the flute and / or liner.

Description

Technical Field

[0001] The present invention relates to fluting or liner comprising neutral sulfite semi-chemical (NSSC) pulp. Background Art

[0002] Corrugated cardboard (sometimes referred to as corrugated cardboard or corrugated fiberboard) is a packaging material that can be converted into various types of packaging solutions. Corrugated cardboard is a fibrous base material made of regenerated cellulose fibers derived from virgin or post-consumer cardboard or other materials.

[0003] Corrugated cardboard comprises a corrugated core (fluting) and at least one flat base paper (liner or linerboard) adhered to the surface of the corrugated core. For example, corrugated cardboard may consist of a layer of fluting adhered between two layers of liner to form a sandwich structure. The sandwich structure can be formed in various forms such as single-wall, double-wall and triple-wall, for example as described in Kirwan M., J., Paper and Paperboard. Packaging Technology, Blackwell Publishing 2005.

[0004] One difficulty in the production of corrugated cardboard is the adhesion between the liner and the fluting. Too low adhesion causes delamination, while adding too much adhesive to ensure sufficient adhesion may cause washing board effect and curling of the corrugated cardboard. It is important that the adsorption of the added glue to the liner and / or the corrugated core is optimal. If the adhesive is not adsorbed on the fluting / liner, delamination occurs, and the same happens if too much is adsorbed on the fluting / liner.

[0005] Examples of different types of liners are kraft liners and test liners. Kraft liners are typically produced from kraft pulp, which can be bleached or unbleached, and may contain one or more layers / plies, where the top layer / ply is often optimized to provide a good print surface and good moisture resistance. Test liners are primarily produced from recycled corrugated cardboard and are usually made with two layers / plies. Due to the presence of recycled fibers, test liners may typically have lower mechanical strength than kraft liners, especially lower burst strength. Kraft liners are often used in packaging boxes where higher strength characteristics are required.

[0006] Fluting is formed from paper or cardboard that has been corrugated using a corrugator with heat, moisture, and pressure.

[0007] Fluting is often prepared from neutral sulfite semi-chemical (NSSC) pulp. NSSC pulp, typically made from hardwoods, is notable for its exceptional rigidity and high hardness, making it suitable for use in fluting. Neutral sulfite semi-chemical (NSSC) pulping is a well-known and long-established process in the field of paper pulping. One reason for using NSSC pulping is its high yield, typically exceeding 60%. In NSSC pulping, the pulp contains sulfites such as Na2SO3 or (NH4)2SO3 and bases such as NaOH or Na2CO3. "Neutral" means that the pH of the NSSC pulp is generally between 6 and 10. The pulp can be pulped in batch or continuous pulping machines. Typically, the pulping time is 5 minutes to 3 hours, and the pulping temperature is 160 to 200°C. NSSC pulp contains a relatively high amount of residual lignin, typically 15-20%, which makes it hard. The Kappa number of NSSC pulp is usually above 70. NSSC pulping is "semi-chemical" in the sense that it also includes mechanical refining of the pulp. Refining can be done, for example, using a disc refiner at digester pressure or atmospheric pressure.

[0008] Currently, the fluting and core strength and mechanical properties are improved by adding small amounts of chemical pulp to mechanical pulp. Typically, 5-15% chemical pulp is added. This naturally increases costs but also reduces the dewatering rate. One possible method is to mix semi-chemical pulp, such as NSSC, with unbleached kraft pulp, but this can result in undesirable light spots and color variations, as well as changes in sensory properties.

[0009] The fluting and liner are bonded to each other by placing an adhesive between the core and the liner. The liner is bonded to at least one surface of the core by the adhesive. The adhesive is preferably applied to at least one surface of the grooved core, after which the liner is bonded to the surface. Any adhesive conventional in the art can be used. The adhesive may be, for example, a starch-based glue that can be extracted from a wide variety of plants. Some of the most common plants are corn, wheat, barley, rice, potato, tapioca, and pea. The starch is preferably natural, i.e., unmodified starch. The adhesive may also contain water, sodium hydroxide, and boric acid. Other additives may be added, such as additives that improve wet strength or adhesive bond strength. Other functional chemicals, such as borax, glyoxal, or mixtures thereof, may also be added, for example, to improve moisture resistance or gelling behavior.

[0010] One significant challenge when creating corrugated cardboard and cardboard is moisture resistance. When cardboard is exposed to moisture, water and water vapor can diffuse through the liner, causing the cardboard to soften. A common solution to this problem is to increase the basis weight of the fluting and / or liner, but this conflicts with environmental demands for lower basis weight materials that consume less raw materials.

[0011] Another solution is to add a barrier layer to the liner to reduce the permeability of water and water vapor. However, this is simply an incomplete solution because moisture can still diffuse on the opposite side or through the edges, consequently affecting the mechanical stability of the corrugated cardboard. In addition, the barrier layer increases costs and typically reduces the recyclability of the material.

[0012] The fluting or core may also be treated or coated with hydrophobic agents, but this generally increases costs and can negatively affect the mechanical properties of the fluting. High levels of hydrophobic agents can also impair the adhesion between the fluting and the liner. NSSC pulp, in particular, requires high levels of hydrophobic agents to achieve the level of water resistance required in the finished fluting.

[0013] New machine concepts and increased machine speeds, coupled with the growing demand for resource conservation, further increased the need for pulp with improved properties.

[0014] There remains a need for new and improved fluting and liner materials that combine strength, low basis weight, water / moisture resistance, low chemical consumption, low cost, and / or high recyclability. [Overview of the project]

[0015] The purpose of this disclosure is to provide a fluting or liner that solves or improves at least some of the problems described above.

[0016] A further object of this disclosure is to provide a fluting or liner having improved water resistance properties that can reduce the amount of hydrophobic internal sizing agent required to obtain the required level of water resistance in the finished fluting or liner.

[0017] A further object of this disclosure is to provide corrugated cardboard including improved fluting and / or liner.

[0018] The purposes described above, as well as other purposes that would be understood by those skilled in the art in light of this disclosure, are achieved by various aspects of this disclosure. [Modes for carrying out the invention]

[0019] This invention is based on the inventive recognition that reducing the ash content of NSSC pulp used in flutting or liner significantly reduces the amount of hydrophobic internal sizing agents required to achieve the desired level of water resistance in the finished flutting or liner. It has also been found that reducing the ash content of the pulp reduces the amount of other wet-end chemicals required in the flutting or liner, such as water-repellency / yield-enhancing agents.

[0020] A reduction in ash content can be achieved by washing the pulp. Ash content can also be reduced by more efficient removal of bark prior to the pulping process.

[0021] A fluting or liner for corrugated cardboard is provided according to a first embodiment shown herein, wherein the NSSC pulp comprises neutral sulfite semichemical (NSSC) pulp, the NSSC pulp having an ash content of less than 1.8 wt% as determined in accordance with ISO standard 1762:2019.

[0022] "NSSC pulp" is obtained by "NSSC pulping" and is defined in the background art section. NSSC pulp can be hardwood pulp, softwood pulp, or a mixture thereof. NSSC pulp is preferably a hardwood / softwood pulp mixture containing less than 15 wt% softwood, preferably less than 10 wt% softwood, and more preferably less than 5 wt% softwood. The hardwood may be, for example, aspen, alder, poplar, eucalyptus, birch, acacia, or beech. NSSC pulp is pulped using a pulp containing preferably sulfite, preferably Na2SO3 or (NH4)2SO3, and a base, preferably NaOH or Na2CO3. In some embodiments, the yield from NSSC pulping is greater than 60%, preferably greater than 65%, preferably greater than 70%, and more preferably greater than 75%. The term "neutral" means that the pH of the NSSC pulp is in the range of 6 to 10. The pulping time is preferably in the range of 5 minutes to 3 hours. The pulping temperature is preferably in the range of 160 to 200°C. NSSC pulp may contain a relatively high amount of residual lignin, such as 15 to 20%. The Kappa number of NSSC pulp is typically greater than 70, preferably greater than 80, preferably greater than 95, and more preferably greater than 100, according to ISO 3260. NSSC pulping is "semi-chemical" in the sense that it also includes mechanical refining of the pulp. Refining can be carried out, for example, using a disc refiner at pulping vessel pressure or atmospheric pressure. Refining can be carried out in one or more steps at the same or different pulp consistency. The first refining step may preferably be carried out at a higher consistency, such as 5 to 35%, and the second refining step may preferably be carried out at a lower consistency, such as <5%.

[0023] In some embodiments, the NSSC pulp in the fluting or liner is subjected to washing to reduce the ash content. The purpose of washing is to separate the pulp from the black liquor, wash away residual substances such as alkaline lignin produced in the digestion process, and purify the pulp. Washing can be performed using one or more conventional pulp washing methods and washing equipment, including but not limited to rotary vacuum washers, rotary pressure washers, pressure and atmospheric diffusion washers, horizontal belt washers and / or dilution / extraction machines. Washing involves diluting the NSSC pulp with water, and then removing the diluted colloidal substances, salts, impurities, and fine particles together with the water using a wire.

[0024] In some embodiments, the NSSC pulp is prepared from wood containing less than 3 wt%, less than 2.5 wt%, less than 2 wt%, or preferably less than 1 wt% or less than 0.8 wt% of bark.

[0025] The reduction in ash content can be measured by measuring the ash content in accordance with ISO standard 1762:2019. In some embodiments, the NSSC pulp has an ash content of less than 1.6 wt%, preferably less than 1.4 wt%, more preferably less than 1.2 wt%, or less than 1.0 wt%, or less than 0.9 wt%, as determined in accordance with ISO standard 1762:2019. In some embodiments, the flutting or liner has an ash content of less than 1.6 wt%, preferably less than 1.4 wt%, more preferably less than 1.2 wt%, or less than 1.0 wt%, or less than 0.9 wt%, as determined in accordance with ISO standard 1762:2019.

[0026] A reduction in ash content can also be measured by measuring the conductivity of hot water extracts of NSSC pulp in accordance with ISO 6587. In some embodiments, the NSSC pulp has a hot water extract conductivity, determined in accordance with ISO 6587, of less than 15 mS / cm, preferably less than 10 mS / cm, more preferably less than 8 mS / cm. In some embodiments, the fluting or liner has a hot water extract conductivity, determined in accordance with ISO 6587, of less than 15 mS / cm, preferably less than 10 mS / cm, more preferably less than 8 mS / cm.

[0027] In some embodiments, the conductivity of NSSC pulp used for fluting or liner, when disintegrated at 3.5 wt% in distilled water, is less than 1200, less than 1000, less than 800, or less than 600, more preferably less than 500, less than 450, less than 400, less than 350 or less than 300 mS / m.

[0028] In some embodiments, the NSSC pulp comprises less than 2%, preferably less than 1.8%, more preferably less than 1.6% Pulmac shives (0.1 mm slot size). It has been found advantageous to use pulp having a low shive content.

[0029] In addition to reducing ash content, washing can also cause a reduction in the content of cellulose fines in the NSSC pulp. As used herein, the term cellulose fines generally refers to cellulose particles that are substantially smaller in size than cellulose fibers. In some embodiments, the term fines as used herein refers to fine cellulose particles that are capable of passing through a 200-mesh screen (equivalent hole diameter 76 μm) of a conventional laboratory fractionation device (SCAN-CM 66:05). The reduction of fines in NSSC pulp can be, for example, in the range of 0.1 to 10 wt%, or in the range of 0.5 to 7 wt%.

[0030] The inventors have found that by reducing the ash content of NSSC pulp, the amount of hydrophobic internal sizing agent required to obtain the level of water resistance needed in the finished fluting or liner can be significantly reduced.

[0031] Therefore, NSSC pulp is used in pulp compositions used for fluting or linering for corrugated cardboard, where the pulp composition further comprises at least one internal sizing agent. The term “pulp composition” means an aqueous dispersion of cellulose fibers and non-fibrous additives used as a furnishing for making paper or cardboard in a paper machine.

[0032] The pulp in the pulp composition of the fluting or liner preferably consists mainly of NSSC pulp. Preferably, at least 50 wt% of the pulp composition is NSSC pulp based on the dry weight of the pulp. In other examples, at least 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 98 wt% of the pulp is NSSC pulp based on the dry weight of the pulp.

[0033] The non-NSSC pulp portion of a pulp composition may contain any kind of fiber, such as hardwood and / or softwood fibers, and may include, for example, chemical pulp, mechanical pulp, thermomechanical pulp, or chemothermetic pulp (CTMP). The non-NSSC pulp portion of a pulp composition may also contain, for example, regenerated fibers. For example, the pulp of this disclosure may consist essentially of NSSC pulp or a mixture of NSSC pulp and regenerated fibers. "Regenerated fibers" means fibrous material that has previously been incorporated into some kind of paper or board product. Alternatively, or as a supplement, the non-NSSC pulp portion may include, for example, rejected pulp. For example, the pulp of this disclosure may consist essentially of NSSC pulp and rejected pulp. "Rejected pulp" means pulp prepared by refining screen rejects from a pulping process.

[0034] In some embodiments, the pulp of the pulp composition contains less than 10 wt%, preferably less than 5 wt%, and more preferably less than 2 wt% of regenerated fibers. Since a high amount of inorganic material is usually added via regenerated fibers, a low amount of regenerated fibers is preferred. In some embodiments, the fluting contains less than 10 wt%, preferably less than 5 wt%, and more preferably less than 2 wt% of regenerated fibers.

[0035] Fluting and / or liners may further contain an internal sizing agent. The internal sizing agent is preferably a hydrophobic sizing agent. In some embodiments, the internal sizing agent is selected from the group consisting of alkyl ketene dimers (AKD), alkenyl succinic anhydride (ASA), rosin sizing, and mixtures thereof. In preferred embodiments, the internal sizing agent is alkyl ketene dimer (AKD).

[0036] In some embodiments, the amount of internal sizing agent in the flutting or liner is in the range of 0.5 to 6 kg / tn, preferably 0.5 to 4 kg / tn, preferably 0.5 to 3 kg / tn, and more preferably 1 to 2 kg / tn, based on dry weight. As a result, the amount of sizing agent in the flutting or liner is extremely low.

[0037] At least one side of the fluting or liner preferably has a Cobb 30s value of less than 30, preferably less than 25, and more preferably less than 22, as determined according to ISO standard 535. It would be preferable for both sides of the fluting or liner to have a Cobb 30s value of less than 30, preferably less than 25, and more preferably less than 22, as determined according to ISO standard 535. Surprisingly, it has been found that the addition of clean NSSC pulp to the bottom or top ply of the liner or fluting does not negatively affect the Cobb value. As a result, the side of the liner or fluting containing clean NSSC pulp preferably has a Cobb 30s value of less than 30, preferably less than 25, and more preferably less than 22, as determined according to ISO standard 535. NSSC pulp is often used in the back ply of the fluting or liner, and as a result, it is preferable for the back side of the fluting or liner to have a Cobb 30s value of less than 30, preferably less than 25, and more preferably less than 22, as determined according to ISO standard 535.

[0038] To produce high-quality paper, such as fluting or liner, from large quantities of NSSC pulp at high machine speeds, it is crucial to effectively retain inorganic fillers and fibrous microparticles while simultaneously achieving high dewatering rates. To help address these challenges, microparticle retention systems have been developed that utilize particles typically based on anionic colloidal silica and / or clay in combination with cationic polymers. Generally, microparticle retention systems exhibit better retention and dewatering performance compared to classical single- or binary polymer retention systems. In some embodiments, fluting or liner further includes a microparticle retention system, preferably a multi-component microparticle retention system.

[0039] In some embodiments, the microparticles of the microparticle retention support system are selected from the group consisting of silica microparticles, bentonite microparticles, and cellulose nanoparticles.

[0040] In some embodiments, the microparticle retention support system includes a water-soluble polymer, preferably a cationic polymer.

[0041] In some embodiments, the amount of the fluting or fine particle retention support system within the liner is in the range of 50 g / tn to 5 kg / tn, more preferably 100 g / tn to 2 kg / tn, based on dry weight.

[0042] Fluting or liner may further contain additional components commonly used in fluting or liner production, such as natural starch or starch derivatives, microfibrillated cellulose (MFC), cellulose derivatives, such as sodium carboxymethylcellulose, fillers, yield-enhancing and / or drainage-enhancing agents, flocculants, degaussing agents, dry strength additives, softeners, crosslinking aids, sizing agents, dyes and colorants, wet strength resins, solidifying agents, defoaming aids, microbial and slime control aids, or mixtures thereof.

[0043] Fluting or liners are typically single-ply products, but may be multi-layer products. Fluting or liners are typically formed on a gap former, but may be formed on a wire mesh former. The press section may be equipped with a shoe press to maximize production.

[0044] The basis weight of the fluting or liner may preferably be in the range of 80 to 300 gsm.

[0045] In some embodiments, the fluting or liner has an equilibrium moisture content (EMC) of less than 10 wt%, preferably less than 8 wt%, at 50% RH, as determined according to ISO standard 287.

[0046] In some embodiments, the fluting or liner has a cd / md elongation value greater than 1.8, preferably greater than 1.9, and more preferably greater than 2.0, as determined according to ISO standard 1924-3.

[0047] In some embodiments, the fluting or liner has a dynamic friction of less than 0.5, preferably less than 0.45, and more preferably less than 0.4, as determined according to the standard ASTMD 1894-63.

[0048] Corrugated cardboard including fluting and / or liner according to the first embodiment is provided in accordance with a second embodiment shown herein. The corrugated cardboard includes at least one layer of uncorrugated liner and at least one layer of fluting. In normal corrugated cardboard production, the fluting is corrugated and then bonded to the linerboard. For example, the corrugated cardboard may consist of a layer of fluting sandwiched between two layers of liner.

[0049] While the present invention has been described with reference to various exemplary embodiments, as will be understood to those skilled in the art, various modifications can be made without departing from the scope of the invention, and equivalents can be substituted for its elements. In addition, many modifications can be made to adapt the teachings of the invention to specific situations or materials without departing from the essential scope of the invention. Thus, the present invention is not limited to the specific embodiments disclosed as the best possible mode for carrying out this invention, and the present invention is intended to encompass all embodiments that fall within the scope of the appended claims. [Examples]

[0050] The examples demonstrate that washed NSSC pulp can be used for sheet fabrication and provides improved mechanical properties and a different response to liquid absorption.

[0051] Example 1 (Comparison) NSSC beech pulp was obtained in a dry form, then decomposed into finish, and processed at 150 g / m² using a wire mesh pilot paper machine. 2 It was created on a single ply web. The production speed was 45 m / min, and the finish temperature was 45°C.

[0052] Example 2 (Comparison) NSSC beech pulp, similar to that used in Example 1, was refined to a higher SR value, and webs were prepared in the same manner as in Example 1. The increased SR resulting from the refinement particularly increased the tensile index (Geom).

[0053] Example 3 NSSC beech pulp, as used in Example 1, is washed with water (40 m³ per ton of pulp) using an Eimco belt washing device. 3 The material was washed with fresh water. 2.7% of the fine powder, along with the electrolyte, colloidal substances in the liquid phase, and impurities, were removed. As a result of washing, the pH of the pulp suspension increased, supporting the removal of the electrolyte and the reduction in ash content. The web was prepared in the same manner as in Example 1. Small improvements were observed in both tensile strength and elongation.

[0054] Example 4 NSSC beech pulp, as used in Example 1, was mixed with washed NSSC birch waste pulp (washed as described in Example 3). The pulps were mixed in a 50-50 ratio. The web was prepared in the same manner as in Example 1. Significant improvements were observed in both tensile strength and elongation.

[0055] Example 5 In this example, washed NSSC birch waste pulp, as used in Example 4, was used without other fibers. The web was prepared in the same manner as in Example 1. The tensile strength properties and elongation were further improved. TIFF0007927014000001.tif76170TIFF0007927014000002.tif93170

[0056] Example 6 In this example, washed NSSC pulp was added to the liner. The washed pulp has an ash content of less than 1.8 wt%.

[0057] For comparison, unwashed NSSC pulp was added to another liner. The unwashed NSSC pulp had a higher ash content of 1.8 wt%.

[0058] All liners produced contained unbleached kraft pulp (100%) in the top ply and regenerated fiber (RCF) pulp in the back ply, with or without NSSC pulp additive. TIFF0007927014000003.tif101170

[0059] These tests clearly demonstrate that using clean NSSC pulp in the liner provides a liner with a very good Cobb value even on the reverse side, as shown in Sample 3 (S3) in Table 3. The Cobb value is at the same level as the reference sample. As seen in Samples 1 and 2 (S1 and S2), the use of unwashed NSSC pulp clearly results in a high Cobb value for the liner, which means these samples have much lower water resistance. As a result, the present invention makes it possible to produce liners with good (high) water resistance even with low amounts of internal sizing agent addition.

[0060] Unless otherwise specified, the physical properties discussed in this disclosure are determined according to the following standards: Whiteness C / 2°+UV ISO 2470-1 L* C / 2°+UV ISO 5631-1 a* C / 2°+UV ISO 5631-1 b* C / 2°+UV ISO 5631-1 Basis weight ISO 536 Thickness, single sheet ISO 534 Umbrella, single sheet ISO 534 Air permeability GH ISO 5636-5 Cobb 60s ISO 535 Moisture content 50%rh ISO 287 Scott-Bond TAPPI T569 Tensile strength ISO 1924-3 Tensile index ISO 1924-3 Tensile strength md / cd ISO 1924-3 Elongation ISO 1924-3 Tensile stiffness ISO 1924-3 Tensile stiffness index ISO 1924-3 E - Modulus of Elasticity ISO 1924-3 TEA ISO 1924-3 TEA index ISO 1924-3 TEA index ISO 1924-3 Fracture toughness ISO / TS 17958 Fracture toughness index ISO / TS 17958 Tear resistance ISO 1974 Tear index ISO 1974 SCT ISO 9895 SCT index ISO 9895 RCT ISO 12192 RCT index ISO 12192 Rupture Index ISO 2759 Bursting strength ISO 2759

[0061] Unless otherwise specified, standard methods can be applied to determine the physical and mechanical properties in both the cross direction (cd) and the longitudinal direction (md).

Claims

1. A pulp having at least 50 wt% neutral sulfite semichemical (NSSC) pulp, At least one internal sizing agent in the range of 1 to 2 kg / tn based on dry weight, Fluting or liner for corrugated cardboard, including, The aforementioned NSSC pulp includes washed NSSC pulp having a reduced ash content of less than 1.8 wt%, as determined in accordance with ISO standard 1762:2019. Fluting or liner for corrugated cardboard, wherein at least one side of the fluting or liner has a Cobb (60s) value of less than 40 gsm as determined in accordance with ISO standard 535.

2. The fluting or liner according to claim 1, wherein the NSSC pulp has an ash content of less than 1.6 wt% as determined in accordance with ISO standard 1762:2019.

3. The fluting or liner according to claim 1, wherein the NSSC pulp has a hot water extract conductivity of less than 15 mS / cm as determined in accordance with ISO 6587.

4. The fluting or liner according to claim 1, wherein the internal sizing agent is selected from the group consisting of alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), rosin sizing, and mixtures thereof.

5. The fluting or liner according to claim 1, further comprising a fine particle retention support system.

6. The fluting or liner according to claim 5, wherein the fine particle retention support system includes a multi-component fine particle retention support system.

7. The fluting or liner according to claim 5, wherein the fine particles of the fine particle holding support system are selected from the group consisting of silica fine particles, bentonite fine particles, and cellulose nanoparticles.

8. The fluting or liner according to claim 5, wherein the fine particle retention support system comprises a water-soluble polymer.

9. The fluting or liner according to claim 8, wherein the fine particle retention support system comprises a cationic polymer.

10. The fluting or liner according to claim 1, wherein the fluting or liner contains less than 10 wt% of regenerated fibers.

11. The fluting or liner according to claim 1, wherein the fluting or liner has a hot water extract conductivity of less than 15 mS / cm as determined in accordance with ISO 6587.

12. The fluting or liner according to claim 1, wherein the fluting has an equilibrium moisture content (EMC) of less than 10 wt% at 50% RH, as determined in accordance with ISO standard 287.

13. The fluting or liner according to claim 1, wherein the fluting or liner has a cd / md elongation value greater than 1.8 as determined in accordance with ISO standard 1924-3.

14. The fluting or liner according to claim 1, wherein the fluting has a dynamic friction of less than 0.5 as determined in accordance with the standard ASTM 1894-63.

15. Corrugated cardboard comprising fluting or liner according to any one of claims 1 to 14.

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