(I) an adhesive composition comprising a combination of microfibrillated cellulose and (II) at least one metal in oxidation state II or higher.

Abstract

The present invention relates in particular to an adhesive composition comprising i) microfibrillated cellulose and ii) at least one metal in oxidation state II or higher. The invention further relates to the use of such an adhesive composition and to products produced using such an adhesive composition. Furthermore, the invention relates to a method for producing corrugated paperboard or cardboard or solid paperboard or cardboard by using such an adhesive composition.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition comprising, together with and containing at least, i) microfibrillated cellulose (MFC) and ii) a metal in oxidation state II or higher. The present invention further relates to the use of such an adhesive composition and to products manufactured using such an adhesive composition. Furthermore, the present invention relates to a method for manufacturing corrugated cardboard or solid board by using such an adhesive composition. [Background technology]

[0002] A composition comprising at least one solvent, such as water, and at least one compound that is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, is practically suitable for a wide variety of applications. In such applications, the composition is designed to cure at least partially after being deposited on a substrate. Examples of such applications include adhesive films, protective films, primer films, and surface sizing films.

[0003] Examples of such compounds capable of polymerization and hydrogen bonding include starch-based and PVA (polyvinyl alcohol)-based adhesive compositions, which are advantageously used in the packaging industry, for example, to manufacture corrugated cardboard or solid boards, respectively.

[0004] In such adhesive compositions, crosslinking agents are commonly used to improve curing and the bonding between molecules of the composition and to the substrate.

[0005] Boron-containing compounds, such as borax and boric acid, have often been used as crosslinking agents. However, such crosslinking agents generally have at least one, or any combination (including all), of the following drawbacks: • Increased or undesirable toxicity levels • Other potentially harmful (chemical) properties • Negative impacts on the environment • Not biodegradable, or only partially biodegradable.

[0006] Despite these concerns, borax has been, or still is, considered an essential additive for adhesives and various industrial applications. However, borax has become a controversial raw material, not only because it was added as a CMR substance to the Candidate List of Substances of Very High Concern (SVHC) by the European Chemicals Agency (ECHA) in 2011, but also because the cardboard industry is broadly aiming to replace it with other substances. However, replacing borax with other harmless materials is not easy and is one of the major challenges currently facing the cardboard manufacturing industry.

[0007] In the corrugated cardboard production process, the bottleneck commonly encountered is typically at the double backer glue station or the entrance to the heating section, specifically the ability to efficiently bond complex and heavy paper flutes to the liner (see Figure 7). When the corrugated cardboard quality is the heaviest and most complex, the bonding ability and / or gelatinization rate during heating may require further improvement if borax is to be (completely) replaced by MFCs. In some cases, the corrugated cardboard delaminates, or the corrugator must be operated at a lower speed to obtain more heat and overcome this specific drawback. Therefore, a combination of MFCs and (some) borax is still generally considered advantageous to enable high operating speeds when producing these demanding qualities.

[0008] MFCs can also be advantageously used in other adhesive applications, namely to replace boric acid in PVA-based adhesive compositions. While certain improved properties can be achieved by substituting boric acid with MFCs, PVA-based adhesive compositions, specifically when boric acid is (completely) substituted, are still seen to suffer from insufficient low tack in some bonded areas during solid board production.

[0009] Several strategies for substituting boron-containing crosslinking agents, specifically borax, in adhesive compositions have been developed over the past few years. In one strategy, microfibrillated cellulose is used as a complete or partial substitute for borax in starch-based adhesive compositions (International Publication No. 2019 / 034649).

[0010] Another known approach, based on the prior art (e.g., International Publication No. 2013 / 087530), to avoid boron-containing crosslinking agents, specifically borax, in adhesive compositions is to use sodium aluminate to replace borax in starch-based adhesive compositions. In an alkaline aqueous medium, aluminates are Al(OH)4 - It is thought to form ions. Al(OH)4 - Ions are thought to act as crosslinking agents for starch polymers according to the general reaction mechanism described below. [ka]

[0011] However, simply substituting all or most of the borax or boric acid with aluminates does not result in an acceptable adhesive composition.

[0012] Although not wanting to be bound by theory, these groups are not stable enough to allow the colligator to be operated at high speed. Specifically, the reason is that the rheology (viscosity) and elasticity of such groups are not sufficient for applications with strict requirements. In addition, the high water uptake rate of adhesives well-known based on the prior art may have an adverse effect on the quality of the final product.

[0013] Thus, boron-free, specifically borax- and boric acid-free adhesive compositions are still being sought for various applications, specifically for manufacturing cardboard (paper) and solid board.

Summary of the Invention

Problems to be Solved by the Invention

[0014] Based on the above, an object of the present invention is to provide a boron-free, specifically borax- and boric acid-free adhesive composition that avoids or minimizes the drawbacks of the compositions well-known in the prior art as described above. Specifically, it is intended to improve the stability, rheology, initial tack, and adhesion properties of the glue, as well as the processing speed in the cardboard production line.

Means for Solving the Problems

[0015] (i) By using a unique combination of microfibrillated cellulose (MFC) and (ii) a metal in an oxidation state of II or higher as a complete or partial substitute for a boron-containing crosslinking agent, specifically borax and boric acid, these and other objects are achieved.

Effects of the Invention

[0016] According to the present invention, the metal in an oxidation state of II or higher means any metal widely understood by those skilled in the art that is stable in at least one oxidation state of II or higher. For example, alkali metals are not included. This is because they are generally only stable in oxidation state I.

[0017] As is known to those skilled in the art, various metals are stable in two or more oxidation states. Such metals are also called polyvalent metals. For example, aluminum has three stable oxidation states. The most common oxidation state is III (+3). The other two are I (+1) and II (+2). Aluminum in oxidation state I is not compatible with the present invention, while aluminum in oxidation states II and III is.

[0018] According to this invention, the term "oxidation state" should be understood in accordance with IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”), edited by AD McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford (1997), Online version (2019-) created by SJ Chalk, ISBN 0-9678550-9-8. https: / / doi.org / 10.1351 / goldbook

[0019] Metals in oxidation state II or higher may exist as monatomic ions (i.e., ions consisting of exactly one atom), as polyatomic ions (i.e., ions consisting of two or more covalently bonded atoms or metal complexes), as salts, as part of polymer network structures, or in any combination thereof. For example, polyatomic ions may be hydrates or hydroxides, or oxide hydroxides, or any mixture thereof.

[0020] In embodiments of the present invention, the metal in oxidation state II or higher includes a metal selected from Group 2 of the periodic system (PSE), specifically Mg or Ca, or a metal selected from Group 4, specifically Ti, Zr or Hf, or a metal selected from Group 8, specifically Fe, or a metal selected from Group 12, specifically Zn, or a metal selected from Group 13, specifically Al.

[0021] In embodiments of the present invention, the metal in oxidation state II or higher includes metals selected from the group consisting of aluminum, calcium, zirconium, magnesium, zinc, hafnium, or titanium, or any combination thereof, specifically ions, and preferably aluminum ions.

[0022] According to this invention, whenever the term "ion" is used, it refers to a monatomic ion (sometimes referred to as a "naked" ion, e.g., Al 3+ ), as well as polyatomic ions (for example, complex ions with coordinating ligands [e.g., Al(OH)4) - ]) is included.

[0023] This invention is at least partially based on the recognition that the amount of metal in oxidation state II or higher required (relative to the amount of "polymerizable and hydrogen-bondable compounds" and relative to the entire composition) is relatively small in order to achieve the advantageous effects that underlie the invention, specifically the high processing speed in lamination / lamination of boards, specifically paperboard / cardboard. In fact, the amount of metal in oxidation state II or higher required relative to the total amount of the composition is extremely small. Combined with the fact that MFCs are used as the main adjuvant to improve the overall adhesive properties of the adhesive (and to eliminate the use of boron-containing compounds), the invention can provide an adhesive that is entirely natural, and as a whole, highly sustainable and environmentally friendly.

[0024] Therefore, according to the present invention, the relative amount (concentration) of metals in oxidation state II or higher is as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.0005 to 5, preferably 0.001 to 1, more preferably 0.005 to 0.5, even more preferably 0.01 to 0.2, and even more preferably 0.02 to 0.1. (ii) (a) The molar amount of the metal in oxidation state II or higher relative to the weight kg of the dry mass of at least one compound capable of polymerization and hydrogen bonding is 0.002 to 20, preferably 0.05 to 5, preferably 0.08 to 2, and more preferably 0.1 to 1.5, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.001 to 3, preferably 0.05 to 2, more preferably 0.06 to 1.5, more preferably 0.1 to 1, and still more preferably 0.1 to 0.4. It follows at least one of the following.

[0025] According to a first aspect of the present invention, this and other objectives are achieved by the adhesive composition described in claim 1.

[0026] According to a second aspect of the present invention, this and other objectives are achieved by using the adhesive composition of the present invention to manufacture corrugated cardboard or solid board.

[0027] According to a third aspect of the present invention, this and other objectives are achieved by using a combination of (i) MFC and (ii) a metal in oxidation state II or higher to produce an adhesive composition.

[0028] According to a fourth aspect of the present invention, this and other objectives are achieved by the corrugated cardboard and solid board described in the claims.

[0029] According to a fifth aspect of the present invention, this and other objectives are achieved by the method for manufacturing corrugated cardboard as described in the claims. [Brief explanation of the drawing]

[0030] [Figure 1]Figure 1 shows the settings for determining the initial tack, as determined using a method based on ASTM D6195 "loop tack" test. [Figure 2] Figures 2 and 3 show the initial tack for bonding two surfaces using adhesive compositions according to the present invention and comparative compositions (Figure 2, viewed from left to right, shows compositions 15, 14, 11, 12, and 13 described in the "Examples" section; Figure 3 shows compositions 15, 14, 11, and 16 described in the "Examples" section). [Figure 3] Figures 2 and 3 show the initial tack for bonding two surfaces using adhesive compositions according to the present invention and comparative compositions (Figure 2, viewed from left to right, shows compositions 15, 14, 11, 12, and 13 described in the "Examples" section; Figure 3 shows compositions 15, 14, 11, and 16 described in the "Examples" section). [Figure 4] Figure 4 shows the water absorption rates of the adhesive composition according to the present invention and comparative compositions (compositions 15, 14, and 11 described in the "Examples" section). [Figure 5] Figure 5 (upper panel) shows the Brookfield viscosity, storage modulus, and water retention of adhesive compositions based on starch alone, starch plus MFC, starch plus metal ions (all for comparison), and starch plus MFC and metal ions (according to the present invention), while the lower panel shows the viscosity as a function of shear rate for the same compositions. [Figure 6] Figure 6 is a schematic diagram showing a continuous production line for manufacturing corrugated cardboard (single face). [Figure 7]Figure 7 is a schematic diagram showing a corrugated cardboard layer including a single corrugated paper layer with adhesive-coated flute tips, as well as an upper and lower liner. A schematic diagram of a fluted (corrugated) paper piece, i.e., a paper piece that has been brought into contact with a corrugated roll using heat, steam, or both, in order to have a corrugated (fluted) shape, is shown, and this diagram also shows how to exemplary glue the flute tips. This diagram also shows the upper and lower liners attached to the upper and lower tops of the fluted paper, also called the single-facer side and double-backer side of the board, resulting in single-wall corrugated cardboard. [Figure 8] Figure 8 shows typical aluminum species present in aqueous media, according to pH. [Figure 9] Figure 9 shows the gelatinization peak viscosity values ​​of various starch adhesive compositions based on MFC alone, and MFC containing calcium, aluminum, and zirconium ions. [Modes for carrying out the invention]

[0031] This invention is at least in part based on the remarkable discovery that boron-containing crosslinking agents used in adhesive compositions, specifically borax and boric acid, can be completely replaced by a combination of MFCs and metal ions in oxidation state II or higher.

[0032] Al depending on pH 3+ or polyatomic aluminum-containing ions (e.g., Al(OH)4) - It has been found that aluminum sulfate and sodium aluminate, which form situ, are particularly advantageous for preparing adhesive compositions.

[0033] As is known to those skilled in the art, the species of aluminum ions present in aqueous media depend on pH. The main aluminum species at high pH is the aluminate ion Al(OH)4. - In contrast, at low pH, Al 3+It is generally understood that it occupies the majority. Other related species include, among other things, Al(OH)3, Al(OH)2 + , Al2(OH)2 4+ . Furthermore, this type of aluminum species present also depends on temperature and concentration. For example, at high pH and high concentration, a condensation reaction may occur, thereby forming Al2O(OH)5 2- .

[0034] An exemplary overview of the different aluminum species with respect to pH is shown in Figure 8.

[0035] In the present invention, it has surprisingly been found that an adhesive composition in which a boron-containing crosslinking agent, specifically borax and boric acid, is completely replaced by a combination of MFC and a metal in oxidation state II or higher exhibits improved initial tack and adhesion properties, as well as an increased processing speed on a corrugated board production line.

[0036] Specifically, it has been found that the combination of MFC and a metal in oxidation state II or higher achieves an adhesion effect that is higher than the sum of the effects of the individual compounds, i.e., MFC on the one hand and the metal in oxidation state II or higher as a borax substitute on the other hand.

[0037] Thus, it has surprisingly been found that the combination of MFC and a metal in oxidation state II or higher results in a synergistic effect, i.e., it provides improved bond strength and processability that exceed the bond strength and processability obtained when using MFC alone or metal ions in oxidation state II or higher alone.

[0038] According to the present invention, an "adhesive", "adhesive composition" or the like is understood to be a material that is applied to a substrate, for example the surface of an article, and thereby permanently joins these surfaces by an adhesive bonding process. An adhesive is a substance that can form bonds to each of two parts. The final object consists of two sections (substrates) bonded to each other. A specific characteristic of an adhesive is the fact that the amount required for bonding is relatively small compared to the weight of the final object.

[0039] According to the present invention, "borax" and boric acid are not the same compound, and are generally understood to be salts of boric acid, i.e., borax is sodium tetraborate, whereas boric acid is hydrogen borate. However, whenever the term "borax" is used, it refers to boric acid and its alkali metal salts. Specifically, a number of related minerals or compounds that differ primarily in their water of crystal content are called "borax" and are included within the scope of the present invention, specifically including the decahydrate. Commercially available borax is typically partially anhydrous. According to the present invention, the term "borax" also includes boric acid or borax derivatives, such as chemically or physically processed boric acid or borax.

[0040] Unless otherwise specified, all ranges or values ​​expressed with respect to the amount of any component in the composition of the present invention shall be expressed as a weight percentage ("wt. / wt.") of the component relative to the total weight of the adhesive composition.

[0041] According to the present invention, “starch” is a polymer carbohydrate comprising multiple glycosidic bonds, which is (a) polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal of oxidation state II or higher.

[0042] Preferred starch sources include, among others, corn, wheat, peas, potatoes, rice, tapioca, and sago.

[0043] According to the present invention, modified starch is starch that has been chemically processed, for example, by hydrolysis.

[0044] In embodiments of the present invention, the starch is preferably unprocessed wheat starch or corn starch, but may be any starch commonly used in adhesives, i.e., any starch or derivative containing a hydroxyl group that is sufficiently available for copolymerization to occur between the hydroxyl group and other reactants.

[0045] According to the present invention, polyvinyl alcohol (PVA) as at least one compound having the formula / repeating unit - [CH2CH(OH)], (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the groups can be crosslinked with at least one functional group of the microfibrillated cellulose. n This refers to a water-soluble synthetic polymer having -.

[0046] Microfibrillated cellulose (also known as "reticulated" cellulose, superfine cellulose, or "cellulose nanofibrils") is a cellulosic product described, for example, in U.S. Patent No. 4,481,077, U.S. Patent No. 4,374,702, and U.S. Patent No. 4,341,807. According to the present invention, microfibrillated cellulose has at least one length scale (diameter, fiber length) reduced compared to nonfibrillated cellulose. In (nonfibrillated) cellulose, which is the starting product for producing microfibrillated cellulose (typically existing as "cellulose pulp"), there are no individualized and "separated" cellulose "fibril" portions found at all, or at least no significant portions found, or even no prominent portions found. Cellulose in wood fibers is an aggregate of fibrils. Cellulose (pulp) In this process, basic fibrils aggregate to form microfibrils, which further aggregate to form larger fibril bundles, and finally cellulose fibers. The diameter of woody fibers is typically 10–50 μm (the length of these fibers is greater). When cellulose fibers are microfibrillated, a heterogeneous mixture of "released" fibrils with cross-sectional dimensions and lengths ranging from nm to μm may be produced. Fibrils and fibril bundles can coexist in the resulting microfibrillated cellulose. The diameter of the microfibrillated cellulose in this invention is typically in the nanometer range.

[0047] Microfibrillated cellulose is produced by the following process, namely (a) A step of subjecting cellulose pulp to at least one mechanical pretreatment step, (b) A homogenization step (b) in which the cellulose pulp from step (a) that has been mechanically pretreated is subjected to a homogenization step, thereby producing fibrils and fibril bundles with reduced length and diameter compared to the cellulose pulp from step (a), wherein step (b) results in microfibrillated cellulose. The homogenization step (b) is a step (b) which involves compressing the cellulose pulp from step (a) and then subjecting the cellulose pulp to a pressure drop. It can be prepared or obtained by a process that includes at least the following:

[0048] The mechanical pretreatment step is preferably a purification step, or includes a purification step. The purpose of mechanical pretreatment is to increase the accessibility of the cell walls, i.e., increase the surface area, by "beating" the cellulose pulp.

[0049] A purification apparatus preferably used in the mechanical pretreatment step includes at least a rotating disk, where a shear force is applied to the cellulose pulp slurry between at least one rotating disk and at least one stationary disk. Enzymatic (pre)treatment of the cellulose pulp is an optional additional step, either before or in addition to the mechanical pretreatment step. This step may be preferred for several applications. With regard to enzymatic pretreatment related to microfibrillated cellulose, the contents of International Publication No. 2007 / 091942 are incorporated herein by reference. Any other type of pretreatment, including chemical pretreatment, is also included in the scope of the present invention.

[0050] In the homogenization step (b) which is to be carried out after the (mechanical) pretreatment step, the cellulose pulp slurry from step (a) is passed through a homogenizer at least once, preferably at least twice, as described in PCT / EP2015 / 001103, for example.

[0051] In the microfibrillated cellulose described throughout this disclosure, individual fibrils or bundles of fibrils can be easily identified and distinguished by conventional optical microscopy, for example at a magnification of 40X, and / or by electron microscopy (SEM or TEM).

[0052] In this embodiment, the microfibrillated cellulose according to the present invention is characterized in particular by at least one of the following features.

[0053] In embodiments of the present invention, microfibrillated cellulose yields a gel-like dispersion in polyethylene glycol (PEG) as a solvent and measured at a solids content of 0.65% of the MFC, wherein the zero shear viscosity η0 is at least 2000 Pa·s, preferably at least 3000 Pa·s or 4000 Pa·s, more preferably at least 5000 Pa·s, more preferably at least 6000 Pa·s, and still more preferably at least 7000 Pa·s.

[0054] Zero shear viscosity η0 ("viscosity at rest") is a measure of the stability of the three-dimensional network structure that forms a gel-like dispersion.

[0055] The "zero shear viscosity" disclosed and claimed herein is measured as follows. Specifically, the rheological characterization of the MFC dispersions ("comparative" and "based on the present invention") was carried out using PEG 400 as the solvent. "PEG 400" is a polyethylene glycol with a molecular weight of 380-420 g / mol, which is widely used in pharmaceutical applications and is therefore generally known and available.

[0056] Rheological properties, specifically zero-shear viscosity, were measured on an Anton Paar Physica MCR 301 type rheometer. The temperature for all measurements was 25°C, and a "plate-plate" geometry was used (50 mm diameter). Rheological measurements were performed as vibrational measurements (amplitude sweep at frequency 1 Hz) to evaluate the structurality in the dispersion, and as rotational viscosity measurements. In the case of rotational viscosity measurements, viscosity was measured as static viscosity (shear force → 0), and as a function of shear rate to evaluate the shear-thinning properties of the dispersion. The measuring apparatus is further described in PCT / EP2015 / 001103 (EP 3 149 241).

[0057] In this embodiment, the water retention capacity (water holding capacity) of the microfibrillated cellulose is greater than 30, preferably greater than 40, preferably greater than 50, preferably greater than 60, preferably greater than 70, preferably greater than 75, preferably greater than 80, preferably greater than 90, and more preferably greater than 100. The water retention capacity indicates the ability of the MFC to retain water within the MFC structure, which is also related to the accessible surface area. The water retention capacity is measured by diluting the MFC sample to a solid content of 0.3%, and then centrifuging the sample at 1000 G for 15 minutes. The clear aqueous phase is separated from the sediment, and the sediment is weighed. The water retention capacity is expressed as (mV / mT)⁻¹, where mV is the weight of the wet sediment and mT is the weight of the analyzed dry MFC. The measurement method is further described in PCT / EP2015 / 001103 (EP 3 149 241).

[0058] In embodiments of the present invention, the MFC has a Schopper-Riegler (SR) value of less than 95, preferably less than 90, obtained according to the standard defined in EN ISO 5267-1, or in other embodiments, it cannot be reasonably measured according to the Schopper-Riegler method, because the MFC fibers are so small that the majority of these fibers simply pass through the screen defined by the SR method.

[0059] In embodiments of the present invention, the microfibrillated cellulose is unprocessed (natural) microfibrillated cellulose, preferably unprocessed microfibrillated cellulose derived from plant material.

[0060] The viscosity of starch-based adhesives described throughout this application, specifically determined in this example as "Lory viscosity" in units of "seconds," is determined by the following method. Lory viscosity is measured using a Lory viscosity cup (Elcometer Model 2215 / 1) in accordance with the standard ASTM D 1084-D or ASTM D4212. The Elcometer device consists of a conventional cylindrical cup with a needle fixed at the bottom. The cup is first immersed in the adhesive. The adhesive then empties the cup through a relief hole. The flow time is measured as soon as the tip of the needle is identifiable.

[0061] The shear viscosity of the adhesive was determined on a rheometer (Anton Paar Physica MCR 102). A coaxial cylindrical geometry was used. To determine the shear profile, shear rate sweeps of 0.001 1 / s to 1000 1 / s were performed, followed by another shear rate sweep of 1000 1 / s to 0.001 1 / s at 25°C. Shear viscosity was measured as a function of shear rate.

[0062] The storage modulus of the adhesive was determined using a rheometer (Anton Paar Physica MCR 102). A coaxial cylindrical geometry was used. To determine the storage modulus, strain rate sweeps of 0.01 to 1000% were performed at a constant frequency of 1 Hz and 25°C. The storage modulus was determined as the average of the storage modulus values ​​corresponding to the linear viscoelastic plateau. Gelatinization peak viscosity was measured by increasing the temperature.

[0063] While we do not wish to be bound by theory, it is conceivable that a network structure is obtained by adding microfibrillated cellulose to a composition comprising at least one compound (for convenience, this compound is also referred to herein as "at least one compound"), which is (a) polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, the groups of which can crosslink with at least one functional group of the microfibrillated cellulose. This network structure is based on physical and / or chemical interactions via hydrogen bonding between the microfibrillated cellulose units and the at least one compound.

[0064] Microfibrillated cellulose is an efficient thickener in polar, specifically protic, solvent systems, and specifically in water, forming a large three-dimensional fibril network structure stabilized by hydrogen bonding.

[0065] MFC fibrils contain hydroxyl groups on their surface. The hydroxyl groups are dissociated at high pH (O - This, in turn, leads to intra- and inter-particular interactions between particles.

[0066] Starch is essentially composed of amylose and amylopectin. Amylose is a helical polymer consisting of α(1→4)-linked D-glucose units with hydroxyl groups oriented outward from the helix. The fibril network structure of microfibrillated cellulose interacts with these groups through hydrogen bonds, forming a protective layer around the amylose chains, thereby protecting the starch from high shear degradation and stabilizing viscosity. Overall, MFCs are a network structure of entangled fibrils, and these fibrils can trap starch molecules, thus strengthening the starch composition and improving its adhesive properties. The same overall effect is achieved with respect to PVA. It is further conceivable that these network structures are further stabilized by the presence of (relatively small amounts) of metals in oxidation state II or higher, according to the present invention.

[0067] Furthermore, while we don't want to be bound by theory, the water-holding capacity of microfibrillated cellulose is thought to prevent water from moving into and through the paper. Therefore, adding microfibrillated cellulose to adhesives containing the aforementioned "at least one compound" is particularly useful in the manufacture of corrugated cardboard. When water moves from the adhesive into the paper, it can impair the stability of the final corrugated cardboard product and, above all, lead to warping and delamination. In addition, this effect is also advantageous in the manufacture of other board structures, such as solid boards.

[0068] Furthermore, and importantly, although we do not want to be bound by theory, the observation that the water uptake rate decreased upon the addition of MFCs can be explained by the fact that the OH groups of the "at least one compound," such as starch or PVA, which were available for water uptake, instead interact with the MFCs and are therefore no longer available for binding with water.

[0069] A reduction in the water absorption rate of the adhesive is generally desirable, as water absorption in the final product, especially around the edges, leads to swelling and deformation, which is generally undesirable. Furthermore, MFC provides barrier properties to the cured adhesive. These barrier properties seal the edges of the board and improve the water resistance of the cured board and the final product.

[0070] According to the first embodiment, the present invention is an adhesive composition, a) Microfibrillated cellulose and b) Metal ions in oxidation state II or higher, c) At least one compound that is polymerizable or already partially or completely polymerized and has at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and This relates to adhesive compositions containing [specific components].

[0071] In embodiments of the present invention, the adhesive composition has a relative amount (concentration) of the metal in oxidation state II or higher as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.0005 to 5, preferably 0.001 to 1, more preferably 0.005 to 0.5, even more preferably 0.01 to 0.2, and even more preferably 0.02 to 0.1. (ii) The molar amount of the metal in oxidation state II or higher relative to the weight kg of the dry mass of at least one compound capable of polymerization and hydrogen bonding is 0.002 to 20, preferably 0.05 to 5, more preferably 0.08 to 2, and even more preferably 0.1 to 1.5, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.001 to 3, preferably 0.05 to 2, more preferably 0.06 to 1.5, more preferably 0.1 to 1, and still more preferably 0.1 to 0.4. It is characterized by following at least one of the following.

[0072] The amount (concentration) of metals in oxidation state II or higher can be determined by various methods. For example, the amount of metals in oxidation state II or higher can be calculated from a "metal ion source" used to prepare adhesive compositions.

[0073] For example, if 342.13 g of anhydrous aluminum sulfate (Al2(SO4)3) is used to prepare 1 kg of adhesive composition, the adhesive composition will contain 2 moles of aluminum in oxidation state II or higher per kg of adhesive composition. Alternatively, the amount of metal in oxidation state II or higher can be determined directly from the adhesive composition by well-known analytical means. For example, atomic emission spectrometry can be used to determine the amount of metal in oxidation state II or higher in the adhesive composition. Further analytical methods that can be used to determine the amount of metal in oxidation state II or higher in the adhesive composition include, for example, atomic absorption spectroscopy or ICP-MS.

[0074] MFC can be selected from the above and below versions.

[0075] The metal in oxidation state II or higher is preferably aluminum ion, and more preferably Al 3+or containing polyatomic aluminum-containing ions. As described above, the species of aluminum ions present in an aqueous medium depend on pH, temperature, concentration, and other components present. Those skilled in the art know which species are present at which pH (see, for example, Figure 8 reproduced from Panias et al. (2001), Hydrometallurgy, Volume 59, issue 1, pages 15-29).

[0076] The metal ions of the present invention may contain any amount of coordinated crystalline water, or the ions may be part of an oxide / hydroxide mixture.

[0077] The metals present in the compositions of the present invention in oxidation state II or higher are generally derived from a “metal ion source.” As used herein, “metal ion source” means a compound used to introduce metals in oxidation state II or higher into a composition. For example, aluminum sulfate and sodium aluminate are aluminum sources for introducing aluminum in oxidation state II or higher into a composition. As is known to those skilled in the art, aluminum sulfate and sodium aluminate are then, depending on the pH, converted into monatomic ions Al 3+ , or polyatomic aluminum-containing ions, for example, Al(OH4) - It forms (see Figure 8).

[0078] Preferred sources of metal ions include, for example, salts, oxides, and similar materials, which include metals in oxidation state II or higher.

[0079] Preferred aluminum sources in oxidation state II or higher are aluminum sulfate, sodium aluminate (e.g., liquid Na2Al2O4 (sodium aluminum dioxide) or solid NaAlO2 (sodium aluminum oxide), the aluminum content of both of which is calculated as % aluminum oxide), aluminum chloride, aluminum nitrate, aluminum silicate, polyaluminum chloride, ammonium aluminum sulfate, potassium aluminum sulfate, sodium aluminum sulfate, potassium aluminate, or other aluminum derivatives and / or aluminum oxide and / or aluminum hydroxide in liquid or solid form. Particularly preferred aluminum sources in oxidation state II or higher are aluminum sulfate, sodium aluminate, and aluminum hydroxide.

[0080] Preferably, the aluminum ion or aluminum-containing ion is derived from sodium aluminate and / or aluminum sulfate (Al2(SO4)3).

[0081] Other metals with a preferred oxidation state of II or higher include zirconium and calcium.

[0082] Preferably, the metal ion source is present in such an amount that the adhesive composition contains at least one metal in oxidation state II or higher at a concentration of 0.0005 to 5 moles, preferably 0.001 to 1 mole, more preferably 0.005 to 0.5 moles, more preferably 0.01 to 0.2 moles, or more preferably 0.02 to 0.1 moles per kilogram of weight of the entire adhesive composition including the solvent, or The adhesive composition contains at least one metal in oxidation state II or higher at a concentration of 0.002 to 20 moles, preferably 0.05 to 5 moles, preferably 0.08 to 2 moles, and more preferably 0.1 to 1.5 moles, based on the weight kg of the dry mass of at least one compound capable of polymerization and hydrogen bonding.

[0083] This means that when anhydrous aluminum sulfate is used to prepare the adhesive composition, 1 kg of the adhesive composition containing the solvent preferably contains 0.0855 g to 855 g (0.0005 mol to 5 mol), more preferably 0.1711 g to 171.065 g (0.001 mol to 1 mol of aluminum ions), more preferably 0.8553 g to 85.5325 g (0.005 to 0.5 mol of aluminum ions), even more preferably 1.711 g to 34.213 g (0.01 to 0.2 mol of aluminum ions), and even more preferably 3.421 g to 17.1065 g (0.02 to 0.1 mol of aluminum ions) of aluminum sulfate.

[0084] Thus, in one embodiment, the present invention is an adhesive composition, a) Microfibrillated cellulose and b) At least one metal in oxidation state II or higher, derived from a metal ion source used to prepare the adhesive composition, c) at least one compound that (a) is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and Includes, The adhesive composition has a relative amount, i.e., concentration, of at least one metal in oxidation state II or higher, as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.0005 to 5, preferably 0.001 to 1, more preferably 0.005 to 0.5, even more preferably 0.01 to 0.2, and even more preferably 0.02 to 0.1. (ii) (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, the molar amount of the metal in oxidation state II or higher relative to the dry mass kg of the at least one compound is 0.002 to 20, preferably 0.05 to 5, more preferably 0.08 to 2, even more preferably 0.1 to 1.5, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.001 to 3, preferably 0.05 to 2, more preferably 0.06 to 1.5, more preferably 0.1 to 1, and still more preferably 0.1 to 0.4. The description may be made relating to an adhesive composition containing the metal ion source in an amount that conforms to at least one of the following.

[0085] For example, when the metal ion source is aluminum sulfate, the present invention is preferably an adhesive composition. a) Microfibrillated cellulose and b) At least one aluminum in oxidation state II or higher derived from aluminum sulfate (Al2(SO4)3), c) at least one compound that (a) is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and Includes, The adhesive composition contains aluminum sulfate (Al2(SO4)3) in an amount of 0.0855 g to 855 g (0.0005 moles to 5 moles), more preferably 0.1711 g to 171.065 g (0.001 moles to 1 mole of aluminum ions), more preferably 0.8553 g to 85.5325 g (0.005 to 0.5 moles of aluminum ions), more preferably 1.711 g to 34.213 g (0.01 to 0.2 moles of aluminum ions), and more preferably 3.421 g to 17.1065 g (0.02 to 0.1 moles of aluminum ions) per 1 kg of the total adhesive composition including the solvent. It can be described as relating to adhesive compositions.

[0086] A person skilled in the art can calculate the amount of other metal ion sources that result in an adhesive composition containing at least one metal in oxidation state II or higher at a concentration of 0.0005 to 5 moles, preferably 0.001 to 1 mole, more preferably 0.005 to 0.5 moles, more preferably 0.01 to 0.2 moles, and still more preferably 0.02 to 0.1 mol per kilogram by weight of the total adhesive composition including the solvent.

[0087] For example, when sodium aluminate (NaAlO2) provided as Gilunal A (Kurita) with an Al2O3 content of 54% is used as a metal ion source, the sodium aluminate is preferably used in an amount of 0.047g to 472g, preferably 0.094g to 94.4g, more preferably 0.472g to 47.2g, more preferably 0.944g to 18.9g, and more preferably 1.888g to 9.441g per 1kg of the total adhesive composition including the solvent.

[0088] Thus, for example, when the metal ion source is sodium aluminate (a solid powder with an Al2O3 content of 54%), the present invention is preferably an adhesive composition. a) Microfibrillated cellulose and b) At least one aluminum in oxidation state II or higher derived from sodium aluminate (NaAlO2), c) at least one compound that (a) is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and Includes, The adhesive composition contains 0.047g to 472g, preferably 0.094g to 94.4g, more preferably 0.472g to 47.2g, more preferably 0.944g to 18.9g, and more preferably 1.888g to 9.441g of sodium aluminate (Al2O) per 1kg of the total adhesive composition including the solvent. 3 / Contains Na2O It can be described as relating to adhesive compositions.

[0089] Each calculation can be performed by a person skilled in the art for any metal ion source.

[0090] In the present invention, when a metal in oxidation state II or higher is derived from sodium aluminate (for example, in the form of a solid powder with an Al2O3 content of about 54%), it is generally preferable that the sodium aluminate is present in the adhesive composition in an amount such that 1 kg of the adhesive composition contains 0.02 to 0.1 moles of the metal in oxidation state II or higher (aluminum in this case). This means that when a metal in oxidation state II or higher is derived from sodium aluminate, the sodium aluminate is present in the adhesive composition in an amount of 1.889 g to 9.441 g per 1 kg of the entire adhesive composition including the solvent.

[0091] According to the present invention, when the metal in oxidation state II or higher is zirconium (for example, derived from a zirconium(IV) ammonium carbonate solution with a zirconium content of about 15%), it is preferable that the zirconium be present in the adhesive composition in an amount such that 0.0005 to 0.1 moles, preferably 0.001 to 0.05 moles, of the metal in oxidation state II or higher (zirconium in this case) is present per 1 kg of the entire adhesive composition.

[0092] According to the present invention, when the metal in oxidation state II or higher is calcium (for example, derived from 97% CaCO3 calcium carbonate), it is preferable that the calcium ions are present in the adhesive composition in an amount such that 0.05 to 5 moles, preferably 0.1 to 3 moles, of the metal in oxidation state II or higher (calcium in this case) are present in 1 kg of the entire adhesive composition. This means that when the metal in oxidation state II or higher is derived from calcium carbonate, the calcium carbonate is present in the adhesive composition in an amount of 5.2 g to 516 g, preferably 10.3 g to 309 g, per 1 kg of the entire adhesive composition including the solvent.

[0093] Preferably, the solvent used in the composition is a protic solvent. More preferably, the solvent contains water or consists of water.

[0094] Preferably, the MFC has at least one length scale, namely fibril diameter and / or fibril length, where the length scale is reduced relative to the fibril diameter and / or fibril length of unfibrillated cellulose. Preferably, the diameter of the MFC fibrils forming the MFC of the present invention is in the nanometer range, i.e., 1 nm to 1000 nm, preferably on average 10 nm to 500 nm. As described above, the fiber length and diameter can be determined by conventional optical microscopy, for example at a magnification of 40X, and / or by electron microscopy (SEM or TEM), depending on the dimensions of the fiber.

[0095] The amount of MFC in the adhesive composition is 0.001 to 10 wt.%. More preferably, the amount of MFC in the adhesive composition is 0.01 to 5 wt.%, even more preferably 0.01 to 1 wt.%, even more preferably 0.01 to 0.5 wt.%, and even more preferably 0.01 to 0.3 wt.%.

[0096] When a metal in oxidation state II or higher is derived from aluminum sulfate, or when the adhesive composition is Al 3+ When ions are present, the amount (by weight) of MFC in the adhesive composition relative to the total weight of the adhesive composition is 0.01 to 5 wt.%, more preferably 0.01 to 1 wt.%, more preferably 0.01 to 0.5 wt.%, and still more preferably 0.01 to 0.3 wt.%.

[0097] Preferably, the amount of anhydrous aluminum sulfate in the entire adhesive composition is 0.001 to 10 wt.% (w / w). More preferably, the amount of aluminum sulfate in the adhesive composition is 0.01 to 5 wt.%, even more preferably 0.015 to 2 wt.%, and even more preferably 0.03 to 0.5 wt.%. Alternatively, the amount of aluminum sulfate in the adhesive composition is 0.01 to 0.25 wt.%, or 0.1 to 1.3 wt%.

[0098] When a metal in oxidation state II or higher is derived from sodium aluminate, or when the adhesive composition is Al(OH)4 - When ions are present, the amount of MFC in the entire adhesive composition is preferably 0.01 to 5 wt.%, more preferably 0.01 to 1 wt.%, even more preferably 0.01 to 0.5 wt.%, and even more preferably 0.01 to 0.3 wt.%.

[0099] Preferably, the equivalent amount of Al2O3 from sodium aluminate (or aluminum sulfate or other aluminum compounds) in the entire adhesive composition is 0.001 to 3% (w / w). More preferably, the amount of Al2O3 in the adhesive composition is 0.05 to 2%, even more preferably 0.06 to 1.5%, even more preferably 0.1 to 1%, and even more preferably 0.1 to 0.4%.

[0100] Preferably, at least one functional group of the MFC is selected from the group consisting of a hydroxyl group, a carboxyl group, an ester group, an ether group, an aldehyde group, and preferably a hydroxyl group. These groups have been shown to result in particularly good crosslinking with the "at least one compound".

[0101] The solvent is preferably present in an amount of 20-90 wt.% (w / w), preferably 30-80 wt.%, more preferably 40-80 wt.%, and even more preferably 50-80 wt.%. Even more preferably, the solvent is present in an amount of 65-80 wt.%, preferably 69-79 wt.%, relative to the total adhesive composition.

[0102] As described above, MFCs and metals in oxidation state II or higher [e.g., Al] 3+ or Al(OH)4 - This unique combination allows for the complete elimination of borax and / or boric acid without adversely affecting the overall properties of the adhesive composition.

[0103] Thus, according to the preferred embodiment, the adhesive composition contains no or only trace amounts of boron-containing crosslinking agent.

[0104] Preferably, the adhesive composition contains no or only trace amounts of borax and / or boric acid.

[0105] More preferably, the adhesive composition contains no or only trace amounts of boron, regardless of its origin and function. As used herein, “trace amounts” means less than 1000 ppm, preferably less than 500 ppm, more preferably less than 200 ppm, more preferably less than 100 ppm, and more preferably less than 50 ppm.

[0106] Preferably, the weight ratio of MFC to "at least one compound capable of polymerization and hydrogen bonding" is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, and even more preferably 0.0005 to 0.1.

[0107] Preferably, "at least one compound capable of polymerization and hydrogen bonding" is the following compound, i.e. At least one type of starch or starch derivative, specifically dextrin, At least one type of polyvinyl alcohol, At least one type of polyvinyl acetate, At least one type of polyethylene glycol, At least one type of polypropylene glycol, At least one type of polysaccharide, At least one type of carbohydrate, At least one polypeptide, At least one type of acrylate, At least one type of acrylamide, At least one type of ethylene oxide, At least one type of propylene oxide, At least one type of glycol, At least one type of polyether, At least one type of polyester, At least one type of polyol, At least one type of epoxy resin, At least one type of polyurethane, At least one type of polyacrylate, for example, polymethyl methacrylate (PMMA), At least one type of polyurea, and at least one type of carbamide Selected from.

[0108] Preferably, the "at least one compound capable of polymerization and hydrogen bonding" is at least one starch or starch derivative, or at least one polyvinyl alcohol.

[0109] Preferably, the "at least one compound capable of polymerization and hydrogen bonding" is at least one polyvinyl alcohol, and the pH of the adhesive composition is less than 7, preferably 2.0 to 6, more preferably 2.5 to 5.0.

[0110] Preferably, the "at least one compound capable of polymerization and hydrogen bonding" is at least one starch or starch derivative, and the pH of the adhesive composition is greater than 7, preferably 10 to 13, more preferably 10.5 to 12.5, or 11 to 12.

[0111] According to a preferred embodiment, the aluminum ion is Al(OH)4 - The compound is derived from sodium aluminate, and the "at least one compound capable of polymerization and hydrogen bonding" is at least one starch or starch derivative.

[0112] In the embodiment, the amount of microfibrillated cellulose in the (starch-based) adhesive composition is 0.001 to 10 wt%, preferably 0.01 to 5 wt%, more preferably 0.01 to 1 wt%, more preferably 0.01 to 0.5 wt%, and more preferably 0.01 to 0.3 wt%, based on the total weight of the adhesive composition.

[0113] In a preferred embodiment, the amount of microfibrillated cellulose in the (starch-based) adhesive composition is 0.01 to 0.25 wt%.

[0114] In this embodiment as well, the solvent is preferably present in an amount of 20-90 wt.% (w / w), preferably 30-80 wt.%, more preferably 40-80 wt.%, and even more preferably 50-80 wt.%. Even more preferably, the solvent is present in an amount of, for example, 65-80 wt.%, preferably 66-79 wt.%, based on the total weight of the adhesive composition.

[0115] In this embodiment as well, the weight ratio of MFC to "the at least one compound" is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1, even more preferably 0.0005 to 0.03, and even more preferably 0.001 to 0.01 (MFC to starch).

[0116] Preferably, the amount of starch in the adhesive composition is 10 to 60 wt.%, more preferably 15 to 45 wt.%, and even more preferably 20 to 40 wt.%.

[0117] According to another preferred embodiment, the aluminum ion is derived from aluminum sulfate, and the “at least one compound” is at least one polyvinyl alcohol.

[0118] In this embodiment, the amount of microfibrillated cellulose in the (PVA-based) adhesive composition is 0.001 to 10 wt%, preferably 0.01 to 5 wt%, more preferably 0.015 to 1 wt%, more preferably 0.02 to 0.5 wt%, and more preferably 0.05 to 0.3 wt, based on the total weight of the adhesive composition.

[0119] In a preferred embodiment, the amount of microfibrillated cellulose in the (PVA-based) adhesive composition is 0.05 to 0.25 wt%.

[0120] In other embodiments, the solvent is preferably present in an amount of 20-90 wt.% (w / w), preferably 30-80 wt.%, more preferably 40-80 wt.%, and even more preferably 50-80 wt.%. Even more preferably, the solvent is present in an amount of 65-80 wt.%, preferably 69-79 wt.%, based on the total weight of the adhesive composition.

[0121] In another embodiment, the weight ratio of MFC to "at least one compound" is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1, even more preferably 0.005 to 0.1, and even more preferably 0.008 to 0.08 (MFC to polyvinyl alcohol).

[0122] The amount of PVA in the adhesive composition is 1 to 30 wt.%, more preferably 2 to 28 wt.%, even more preferably 3 to 25 wt.%, and even more preferably 3 to 10 wt.%.

[0123] In embodiments of the present invention, further additives, such as calcium chloride, sodium hydroxide, urea, sodium nitrate, thiourea, and guanidine salts, may be used in the adhesive composition according to the present invention. Some or all of these may be used as liquefiers to (further) control viscosity.

[0124] Other embodiments that may be used in the adhesive composition according to the present invention include, for example, preservatives, bleaching agents, and defoaming agents.

[0125] According to a second embodiment, the present invention relates to the use of an adhesive composition according to the present invention for preparing corrugated cardboard or solid board, specifically cardboard or paperboard.

[0126] As described above and as is clear from the examples, the adhesive composition according to the present invention is particularly suitable for manufacturing corrugated cardboard or solid boards.

[0127] Specifically, it has been found that a unique combination of MFCs and aluminum ions or polyatomic aluminum-containing ions produces a synergistic effect, resulting in remarkably good overall adhesion properties even in the complete absence of borax. Such properties have not been previously observed in borax-free adhesive compositions.

[0128] Specifically, the adhesive composition of the present invention has been shown to enable the use of high corrugator operating speeds for all board quality applications, including those where achieving the desired board quality is most challenging. In fact, the adhesive composition of the present invention has been shown to perform better than borax-based adhesive compositions, and also better than MFC (alone) or borax / MFC adhesive glues.

[0129] Furthermore, it has been found that the adhesive composition of the present invention exhibits similar initial tackiness to boric acid-containing PVA (polyvinyl alcohol) adhesive compositions, but at the same time, it shows a significant reduction in water absorption. This significant reduction in water absorption is particularly beneficial for preparing solid boards, which are often used in high-humidity environments such as agriculture or for packaging seafood. These, and other remarkable effects, make the adhesive composition particularly suitable for preparing corrugated cardboard or solid boards (paperboard or cardboard sheets).

[0130] In one embodiment, the adhesive composition according to the present invention is used to prepare corrugated cardboard. In this embodiment, the metal in oxidation state II or higher is preferably Al(OH)4 - The compound is derived from sodium aluminate, and the "at least one compound capable of polymerization and hydrogen bonding" is preferably at least one starch or starch derivative.

[0131] In another embodiment, the adhesive composition according to the present invention is used to prepare a solid board. In this embodiment, the metal in oxidation state II or higher is preferably Al 3+The compound is derived from aluminum sulfate, and the "at least one compound capable of polymerization and hydrogen bonding" is preferably at least one polyvinyl alcohol.

[0132] According to the third embodiment, the present invention comprises an MFC and a metal in oxidation state II or higher, preferably a monatomic aluminum ion or a polyatomic aluminum-containing ion, preferably Al 3+ or Al(OH)4 - In combination use with the Al 3+ It is preferably derived from aluminum sulfate, and Al(OH)4 - This relates to the use of combinations of MFCs and metals in oxidation state II or higher, preferably derived from sodium aluminate.

[0133] According to a fourth embodiment, the present invention relates to corrugated cardboard and solid boards comprising the adhesive composition of the present invention.

[0134] Preferably, the corrugated cardboard contains the adhesive composition of the present invention, and the aluminum ions or polyatomic aluminum-containing ions are Al(OH)4 - It is derived from sodium aluminate, and “at least one compound” is at least one starch or starch derivative.

[0135] Preferably, the solid board contains the adhesive composition of the present invention, and the aluminum ions or polyatomic aluminum-containing ions are Al 3+ It is and / or derived from aluminum sulfate, and “at least one compound” is at least one polyvinyl alcohol.

[0136] According to the fifth embodiment, the present invention is a method for manufacturing corrugated cardboard, wherein the method comprises at least the following steps, i.e. a) Prepare an adhesive composition according to the present invention, b) Prepare flute core paper and liner paper for corrugated cardboard, and optionally, the paper for the flute or the paper for the liner, or both, are at least partially chemically treated or chemically treated. c) The adhesive composition is applied to at least a portion of the top of the flutes of the corrugated paper strip, on at least one side, preferably both sides. d) Within the corrugator, at least one liner is attached to the corrugated paper piece, preferably an additional liner is attached to the other side of the corrugated paper piece, and e) Prepare single, double, triple, or further multi-layer wallboards, preferably in a continuous process. This relates to a method for manufacturing corrugated cardboard, including the manufacturing process.

[0137] The present invention can also be described in relation to the following items. These items can be combined with each and all of the embodiments described above. Item 1: Adhesive composition, a) Microfibrillated cellulose and b) At least one metal in oxidation state II or higher, c) at least one compound that (a) is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and Includes, The relative amounts of at least one metal in oxidation state II or higher are as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.0005 to 5, preferably 0.001 to 1, more preferably 0.005 to 0.5, even more preferably 0.01 to 0.2, and even more preferably 0.02 to 0.1. (ii) (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, the molar amount of the metal in oxidation state II or higher relative to the dry mass kg of the at least one compound is 0.002 to 20, preferably 0.05 to 5, more preferably 0.08 to 2, even more preferably 0.1 to 1.5, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.001 to 3, preferably 0.05 to 2, more preferably 0.06 to 1.5, more preferably 0.1 to 1, and still more preferably 0.1 to 0.4. An adhesive composition that conforms to at least one of the following.

[0138] Item 2 The adhesive composition according to Item 1, wherein the metal in oxidation state II or higher includes aluminum in oxidation state II or higher, calcium in oxidation state II or higher, zirconium in oxidation state II or higher, magnesium in oxidation state II or higher, zinc in oxidation state II or higher, hafnium in oxidation state II or higher, or titanium in oxidation state II or higher, or any combination thereof, preferably including aluminum in oxidation state II or higher.

[0139] Item 3 The adhesive composition according to Item 1 or 2, wherein the metal in oxidation state II or higher contains aluminum ions and is more preferably derived from aluminum sulfate, sodium aluminate, or aluminum hydroxide.

[0140] Item 4 An adhesive composition according to any one of the preceding items, wherein the solvent is a protic solvent.

[0141] Item 5: The adhesive composition according to Item 4, wherein the solvent contains or consists of water.

[0142] Item 6 The adhesive composition according to any one of the preceding items, wherein the microfibrillated cellulose has at least one length scale, i.e., fibril diameter and / or fibril length, and the length scale is reduced relative to the fibril diameter and / or fibril length of the nonfibrillated cellulose, and preferably the diameter of the microfibrillated cellulose fibrils forming the microfibrillated cellulose of the present invention is in the nanometer range, i.e., 1 nm to 1000 nm, preferably on average 10 nm to 500 nm.

[0143] Item 7 The adhesive composition according to any one of the preceding items, wherein the amount of microfibrillated cellulose in the adhesive composition is 0.001 to 10 wt.% (w / w), preferably 0.01 to 5 wt.%, more preferably 0.01 to 1 wt.%, more preferably 0.01 to 0.5 wt.%, and more preferably 0.01 to 0.3 wt.%, based on the total weight of the adhesive composition.

[0144] Item 8 The adhesive composition according to any one of the preceding items, wherein at least one functional group of the microfibrillated cellulose is a hydroxyl group, a carboxyl group, an ester group, an ether group, and an aldehyde group.

[0145] Item 9 The adhesive composition according to any one of the preceding items, wherein the solvent is present in an amount of 20 to 90 wt.%, preferably 30 to 80 wt.%, more preferably 40 to 80 wt.%, even more preferably 50 to 80 wt.%, for example 65 to 80 wt.%, preferably 66 to 79 wt.%, based on the total weight of the adhesive composition.

[0146] Item 10 The adhesive composition according to any one of the preceding items, wherein the composition does not contain or contains only trace amounts of a boron-containing crosslinking agent, preferably the adhesive composition does not contain or contains only trace amounts of borax and boric acid, and more preferably the adhesive composition does not contain or contains only trace amounts of boron.

[0147] Item 11 The adhesive composition according to any one of the preceding items, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups, preferably OH groups, available for hydrogen bonding, wherein the weight ratio of microfibrillated cellulose to at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1 or 0.0005 to 0.03 or 0.001 to 0.01.

[0148] Item 12 (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher, the compound being one of the following compounds, i.e. At least one starch or starch derivative, at least one polyvinyl alcohol, at least one polyvinyl acetate, at least one polyethylene glycol, at least one polypropylene glycol, at least one polysaccharide, at least one carbohydrate, at least one polypeptide, at least one acrylate, at least one acrylamide, at least one ethylene oxide, at least one propylene oxide, at least one glycol, at least one polyether, at least one polyester, at least one polyol, at least one epoxy resin, at least one polyurethane, at least one polyacrylate, e.g., polymethyl methacrylate (PMMA), at least one polyurea, and at least one carbamide, or any combination thereof, Preferably selected from at least one starch or starch derivative and at least one polyvinyl alcohol. An adhesive composition as described in any one of the preceding items.

[0149] Item 13 The metals in oxidation state II or higher are Al(OH)4 - It exists as and / or is derived from sodium aluminate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one starch or starch derivative, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher. An adhesive composition as described in any one of the preceding items.

[0150] Item 14 The adhesive composition according to Item 13, wherein the amount of microfibrillated cellulose in the starch-based adhesive composition is 0.001 to 10 wt%, preferably 0.01 to 5 wt%, more preferably 0.01 to 1 wt%, more preferably 0.01 to 0.5 wt%, and more preferably 0.01 to 0.3 wt%, based on the total weight of the adhesive composition.

[0151] Item 15 The adhesive composition according to item 13 or 14, wherein (a) it is polymerizable or has already partially or completely polymerized, and (b) it has at least two groups, preferably OH groups, available for hydrogen bonding, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1, even more preferably 0.0005 to 0.03, and even more preferably 0.001 to 0.01.

[0152] Item 16 The metal in oxidation state II or higher is Al 3+ It exists as and / or is derived from aluminum sulfate, and, The adhesive composition according to any one of items 1 to 12, wherein (a) it is polymerizable or has already partially or completely polymerized, and (b) it has at least two groups, preferably OH groups, available for hydrogen bonding, wherein the group can be crosslinked with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, the compound being at least one polyvinyl alcohol (PVA).

[0153] Item 17 The adhesive composition according to Item 16, wherein the amount of microfibrillated cellulose in the PVA-based adhesive composition is 0.001 to 10 wt%, preferably 0.01 to 5 wt%, more preferably 0.015 to 1 wt%, more preferably 0.02 to 0.5 wt%, and more preferably 0.05 to 0.3 wt, based on the total weight of the adhesive composition.

[0154] Item 18 The adhesive composition according to item 16 or 17, wherein (a) it is polymerizable or has already partially or completely polymerized, and (b) it has at least two groups, preferably OH groups, available for hydrogen bonding, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1, even more preferably 0.005 to 0.1, and even more preferably 0.008 to 0.08.

[0155] Item 19: Use of any one of the adhesive compositions described in items 1 through 18 for manufacturing corrugated cardboard or solid board.

[0156] Item 20: For the purpose of manufacturing corrugated cardboard, the metal in oxidation state II or higher is Al(OH)4 - It exists as and / or is derived from sodium aluminate, and (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one starch or starch derivative, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher. Use as described in item 19.

[0157] Item 21 The purpose is to manufacture solid boards, and the metal in oxidation state II or higher is Al 3+ It exists as and / or is derived from aluminum sulfate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one polyvinyl alcohol, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher. Use as described in item 19.

[0158] Item 22 Use of any one of the adhesive compositions described in items 1 to 18 as an adhesive, in a paint composition, as a coating, as a (surface) sizing composition, as a composite or in a composite, as a resin, as a paste, as a food thickener or additive, in a gel, in a hydrogel or as an absorbent or in an adhesive coating, protective coating, primer coating or surface sizing coating.

[0159] Item 23 A corrugated cardboard or solid board comprising the adhesive composition according to any one of claims 1 to 18.

[0160] Item 24: Corrugated cardboard containing an adhesive composition as described in any one of items 13-15.

[0161] Item 25: A solid board comprising an adhesive composition as described in any one of items 16-18.

[0162] Item 26 A method for manufacturing corrugated cardboard, wherein the method comprises at least the following steps, i.e. a) Prepare an adhesive composition as described in any one of items 1 to 18, b) Prepare flute core paper and liner paper for corrugated cardboard, and optionally, the paper for the flute or the paper for the liner, or both, are at least partially chemically treated or chemically treated. c) The adhesive composition is applied to at least a portion of the top of the flutes of the corrugated paper strip, on at least one side, preferably both sides, and d) Within the corrugator, at least one liner is attached to the corrugated paper piece, preferably an additional liner is attached to the other side of the corrugated paper piece, and e) Prepare single, double, triple, or further multi-layer wallboards, preferably in a continuous process. A method for manufacturing corrugated cardboard, including the manufacturing process.

[0163] Item 27 Corrugated cardboard obtained or obtainable by the method described in claim 26. [Examples]

[0164] Example 1 Preparation of microfibrillated cellulose (MFC) The MFCs used to prepare the compositions according to the present invention are commercially available and have been commercialized by Borregaard, for example, as “Exilva Microfibrillated cellulose FBX 01-V” or “Exilva Microfibrillated cellulose P01-L” based on cellulose pulp derived from Norwegian spruce (coniferous tree).

[0165] The MFCs used in the examples related to starch as a compound capable of polymerization and hydrogen bonding existed as a paste. The solids content of the paste was 10%, meaning that the dry content of microfibrillated fibers in the MFC paste was 10%, while the remaining 90% was water, which was the only solvent in this case.

[0166] In the examples related to polyvinyl alcohol (PVA) as a compound capable of polymerization and hydrogen bonding, the MFCs used existed as a dispersion. The solids content of the dispersion was 2%, meaning that the dry material content of the microfibrillated fibers in the MFC paste was 2%, while the remaining 98% was water, which was the only solvent in this case.

[0167] Example 2 Improvement of properties of starch-containing adhesive compositions, and their effects on corrugator speed and adhesion [MFC and sodium aluminate (solid)] The compositions shown in Table 1 were prepared according to the following protocol: the adhesives were prepared according to the Stein-Hall method. The primary starch portion was added to the primary water portion at a temperature of 39°C and stirred for 30 seconds before the addition of caustic soda. The primary starch was then stirred for 500 seconds before the addition of MFC. The primary starch and MFC were then stirred for a further 600 seconds, followed by the addition of secondary water and disinfectant. After the addition of the secondary water portion, the temperature of the composition was 31°C. The secondary starch portion was then added and the composition was stirred for 30 seconds, followed by the addition of sodium aluminate. The composition was then stirred for 200 seconds before a final stirring time of 200 ± 700 seconds until a viscosity setpoint of 35 Lory seconds was achieved. For compositions containing borax, 1 / 3 of the borax was added before the addition of the secondary starch, and then 2 / 3 of the borax was added after a 30-second mixing time following the addition of the secondary non-swelling starch.

[0168] Lory viscosity was measured using a Lory viscosity cup (Elcometer Model 2215 / 1). The Lory viscosity cup, widely used in the adhesives, paints, and coatings industries, essentially consists of a conventional cylindrical cup with a needle fixed to the bottom. The cup is first immersed in the adhesive. The adhesive then empties the cup through a relief hole. The flow time was measured as soon as the tip of the needle became visible.

[0169] The Lory viscosity of the comparative starch-based adhesive containing only borax (composition no. 2) readily decreased with mixing time under high shear, whereas the viscosity of the adhesives containing MFC (compositions 1, 3, and 4) exhibited considerably high viscosity stability with respect to high shear mixing. Furthermore, the compositions containing MFC showed significantly higher viscosity stability over time compared to the borax-reference adhesives.

[0170] [Table 1]

[0171] The starch was natural wheat starch supplied by Amilina / Roquette. The borax was Fullbor W6364, commercially available from HB Fuller, and the sodium aluminate was Gilunal A (Al2O3 content 53-55%), commercially available from Kurita. Dry solids content (DS) was calculated for all compositions in both commercial (amount of starch in the total glue) and absolute (for all components, and adjusted according to the dry solids content in each component). The pH of the glue was 11.5-11.7.

[0172] The compositions shown in Table 1 were then used to prepare corrugated cardboard according to the following protocol.

[0173] Starch adhesive compositions 1-4 were tested in corrugated cardboard production using BHS (wet-end) and Fosber (dry-end) corrugators. A corrugator is a series of machines designed to form single, double, or triple-wall corrugated cardboard in a continuous process by bundling several sheets of paper together. The process begins with paper sheets conditioned by heat and steam on corrugated rolls, which impart a flute shape to the paper sheets in the single facer. Next, starch adhesive is applied to the ends of the flutes on one side, bonding the inner liner to the flutes (see Figures 6 and 7). The corrugated core (single facer) with one liner attached is then carried to the double backer, where the outer liner is bonded to the single facer.

[0174] Table 2 shows the corrugator production rates achieved for single-wall B-flute quality and double-wall EB and BC-flute quality for various different compositions 1, 2, and 3.

[0175] [Table 2]

[0176] As is clear from Table 2, the adhesive composition of the present invention enables a significant improvement in production speed in all corrugated cardboard and paper combinations of all qualities tested, compared to the reference composition containing only borax. Furthermore, the adhesive composition of the present invention enables a significant improvement in production speed compared to the reference composition containing only MFC. In the heaviest and most challenging BC combinations, including semi-chemical core paper, the gluing ability of the adhesive composition of the present invention is remarkably better than that of the reference compositions containing only borax and only MFC, improving operational capacity and production speed.

[0177] The initial bond strength of semi-cured corrugated cardboard was measured during and after production by tearing it by hand by a person skilled in the art, and the results were graded according to a predetermined scale. On this scale, 1 was the lowest and 4 was the highest (initial bond strength). After curing and conditioning under controlled temperature and humidity, the final bond strength (Newton (N) / m) was measured by the Pin Adhesion Test (PAT) according to Fefco No. 11 standard. The standard test method is outlined in Table 3.

[0178] [Table 3]

[0179] Table 4 shows the bond strength of corrugated cardboard measured by tearing by hand and by pin bonding tests on the single-facer (SF) and double-backer (DB) sides of B-flute quality 115EK / 100WF / 115EK produced with adhesive compositions 1, 2, 3, and 4. The adhesive composition containing microfibrillated cellulose shows an increase in PAT-DB, measured in N / m of corrugated cardboard, compared to the "borax only" composition. The adhesive composition of the present invention yields overwhelmingly the best bond strength, measured by PAT. The MFC and sodium aluminate composition increases the PAT value by +57% for single faces compared to the MFC and borax composition. The adhesive composition of the present invention also yields the best initial or semi-cured bond strength, evaluated by tearing the board by hand and compared to the borax only or MFC only composition, or compared to the MFC and borax composition.

[0180] [Table 4]

[0181] While we do not wish to be bound by theory, these remarkable results can be explained by the improved wettability, permeability, and elasticity (high storage modulus) of the adhesive. These are provided by the addition of microfibrillated cellulose, combined with the increased hydrogen bonding crosslinking ability of the adhesive upon heating, and provided by the presence of MFCs with available OH groups and dissolved sodium aluminate. These are thought to act synergistically; that is, the combined contribution of stability, elasticity, and adhesion is greater than the contribution of each component added individually. One other explanation for the remarkable improvement in the strength of the semi-cured and fully cured glue bonds may be that the MFCs capture the starch granules and retain moisture around the granules, while more of the raw starch is gelatinized. Aluminum ions may provide a more uniform and higher heat transfer rate, thus enhancing adhesion. Another explanation is that the dissolved sodium aluminate improves the interaction with the paper surface fibers, either directly or by crosslinking. The use of sodium aluminate in the papermaking industry to increase paper strength is widely known. At a pH of approximately 11.5 (for example, in the case of starch adhesives), molecular dynamics simulations show that aluminate ions strongly interact with the bonding of polyvalent positive ions on the surface, as well as with interfacial hydrogen bonds.

[0182] I don't want to be bound by theory, but as a major aluminum-supported compound at low concentrations, tetrahedral Al(OH)4 - The properties of an alkaline (high pH) aluminate solution of sodium aluminate, which has the properties of Al2O(OH)5, are more pronounced in higher concentrations. 2- It is thought that this causes condensation necessary for the formation of [the compound].

[0183] Overall, all boards containing MFC in the adhesive composition are flatter than boards without MFC.

[0184] Overall, the combination of MFC and sodium aluminate according to the present invention significantly improves glue performance. This improvement in glue performance is expressed by a significant increase in production speed and corrugated cardboard bonding strength compared to a reference glue containing only boron. Compared to a reference adhesive containing only borax, the adhesive combining MFC and sodium aluminate can even increase production speed by up to 56%. For corrugated cardboard qualities with "moderate" complexity, a boron-free adhesive containing only MFC performs well. However, current results clearly indicate that using the adhesive composition of the present invention further improves operating speed and board quality. Thus, the adhesive of the present invention makes it possible to use the same (boron-free) adhesive for all corrugated cardboard qualities. This is a significant advantage for the industry.

[0185] In summary, the adhesive composition of the present invention has been shown to exhibit high stability during processing and storage, provide extremely good adhesive performance, result in flat boards, and enable high production speeds across all board qualities.

[0186] These results are further supported by laboratory tests demonstrating the excellent effect of the MFC and aluminate combination on adhesive properties.

[0187] Figure 5 shows the Brookfield viscosity, storage modulus (elasticity), and water retention of adhesives consisting of starch alone, MFC alone, sodium aluminate alone, and the MFC-sodium aluminate adhesive according to the present invention. The laboratory recipes and preparation procedures for each adhesive are shown in Table 5.

[0188] As can be seen from the three upper panels of Figure 5, sodium aluminate alone does not significantly contribute to Brookfield viscosity. However, MFC significantly increases the viscosity of the glue.

[0189] The combination of MFC and sodium aluminate, while not containing metal ions (in this case, aluminates), provides a similarly high viscosity to other adhesives, while significantly increasing water retention.

[0190] Unlike conventional adhesives that do not contain MFCs, the two adhesives with a storage modulus of 31 Pa shown in Figure 5 (both containing MFCs) exhibit primarily elastic behavior within the linear viscoelastic range, and a plateau value is determined.

[0191] The overall data in Figure 5 suggests that the combination of MFC and sodium aluminate produces a gel-like material and, consequently, exhibits a better ability to stabilize both gelatinized starch and raw starch.

[0192] Sodium aluminate has little effect on the water retention of adhesives. This is because the water retention value of adhesives containing sodium aluminate is similar to that of adhesives that do not contain additives.

[0193] The water retention value of the combination of MFC and sodium aluminate is higher than that of equivalent single-additive adhesives.

[0194] The lower panel of Figure 5 clearly shows that the presence of MFCs results in higher viscosity at low shear rates while maintaining significant shear viscosity reduction behavior. This high viscosity at low shear allows the adhesive to keep gelatinized and raw starch suspended. This suggests that the presence of MFCs, even in combination with sodium aluminate, provides an opportunity to formulate a more stable adhesive while maintaining easy processability.

[0195] Overall, sodium aluminate alone does not significantly contribute to the viscosity, storage modulus, or water retention of the adhesive, whereas the combination of aluminate and MFC clearly improves rheological properties and water retention. Gelatinization tests further demonstrate that the combination of aluminate and MFC results in a gelatinization profile compared to borax reference glue. The results demonstrate the superior adhesive of the present invention, which has a unique combination of rheological properties, water retention values, and gelatinization profile that is beneficial for corrugated cardboard manufacturing. Similar results were obtained with corn starch.

[0196] [Table 5]

[0197] Example 3 Improvement of properties of starch-containing adhesive compositions, and their effect on adhesion (MFC and metals) Example 2 above demonstrated that the combination of MFC and sodium aluminate can improve the properties of starch-containing adhesives and enhance production rate and adhesion. In this example, the effect of combinations of MFC with other metals in oxidation state II or higher on glue properties is investigated in the laboratory. Combinations of MFC with sodium aluminate, calcium carbonate, and ammonium zirconium carbonate (AZC) were tested in starch adhesives and compared with starch adhesives containing MFC alone. Gelatinization peak viscosity, which reflects the glue capacity and bonding rate at the inlet of the corrugator heating section, and the water retention of the adhesive were determined. The compositions are shown in Table 6 and were prepared according to the Stein-Hall method (procedure shown in Table 5).

[0198] [Table 6]

[0199] The starch used for laboratory testing was natural wheat starch supplied by Amilina / Roquette. Borax was Fullbor W6364, commercially available from HB Fuller, and sodium aluminate was Gilunal A (Al2O3 content 53-55%), commercially available from Kurita. Calcium carbonate was Rollovit 30, obtained from Lhoist (CaCO3 content 95-97%). Zirconium ammonium carbonate (zirconium content 15%) was purchased from Sigma Aldrich. Dry solids content (DS) was calculated on a commercial basis (amount of starch in total glue). The pH of the glue was 11.5-11.8.

[0200] Figure 9 shows the gelatinization peak values ​​of various starch adhesive compositions 9-12. The comparative sample (composition no. 9) exhibits the lowest gelatinization peak value. The three adhesive compositions 10-12 of the present invention show similar values ​​when compared to each other, but are 2.3-2.7 times higher than the comparative composition. The importance of gelatinization peak viscosity was demonstrated in several factory tests. High gelatinization peak values ​​reflected high production speeds during corrugated cardboard manufacturing. Specifically, high gelatinization peak viscosity was found to be decisive for high-speed production in corrugators carried out under difficult conditions at the entrance of the heating section (e.g., unoptimized angles of bars and liners). These results clearly demonstrate that the combination of MFC with aluminum, as well as the combination of MFC with metallic calcium and the combination of MFC with metallic zirconium, yields excellent effects in improving the adhesive properties of starch adhesives.

[0201] Furthermore, similar to those shown for the compositions of the present invention containing MFC and aluminum in Example 2, the water retention values ​​for the combination of MFC and zirconium, and the combination of MFC and calcium, are higher than those for the comparative compositions that do not contain the respective metal ions.

[0202] While I don't want to be bound by theory, it is thought that the higher the oxidation state of the metal, the lower the molar amount of metal required to achieve improved adhesion relative to the weight of MFC, or the weight of the polymerizable compound (in this case, starch), or the total weight of the adhesive composition.

[0203] Example 4 Improvement of properties of starch-containing adhesive compositions, and their effects on corrugator speed and adhesion [MFC and sodium aluminate (liquid)] Compositions No. 13 and 14 of the present invention, shown in Table 7, containing MFC and liquid sodium aluminate, were prepared according to the protocol shown in Example 2. The starch was natural wheat starch supplied by Amilina / Roquette. The sodium aluminate was AluPurePlus (APP) with an Al2O3 content of 19.9%, available from Alumichem. The concentrations of primary starch and caustic soda were adjusted accordingly to achieve a viscosity of 35 Lory seconds and a pH of 11.7.

[0204] [Table 7]

[0205] Compositions No. 13 and 14 in Table 7 were used when producing corrugated cardboard according to the protocol described above (Example 2). The performance of composition No. 13 was compared to that of composition No. 4 (Table 1) in double-walled EB flute quality including white liner paper. The same corrugator settings and production speed were used for both glues. The corrugated cardboard properties were analyzed and are shown in Table 8 below.

[0206] [Table 8]

[0207] Adhesive compositions containing a combination of MFC and aluminum increase the bond strength of the upper double backer (db) by 33% compared to the MFC-borax composition (Table 8). Furthermore, the MFC-aluminum composition of the present invention increases ECT and torsional stiffness by 2.6% and 17.5%, respectively, compared to the comparative composition. When operated at the same corrugator setting, the higher dryness of the adhesive of the present invention likely contributed to the increased calculated glue consumption compared to the MFC-borax composition. Glue consumption was calculated according to the following method and equation: Weight of air-dried corrugated cardboard (under constant temperature and humidity conditions) - Ideal weight of paper = Difference = Glue consumption.

[0208] The performance of composition no. 14 of the present invention, which is less dry than composition no. 13 and contains the same dry solids content as comparative composition no. 4, was tested in double-wall BC quality with semi-chemical core paper. The same corrugator settings and production speed were used for both glues. The corrugated cardboard properties were analyzed and are shown in Table 9 below.

[0209] [Table 9]

[0210] Even in this challenging BC quality, adhesive compositions containing a combination of MFC and aluminum increased the bond strength for both the upper and lower double backers (db) by 7.1% and 12.9%, respectively, compared to MFC-borax compositions (Table 9). Furthermore, the MFC-aluminum composition of the present invention increased ECT and torsional stiffness by 2.8% and 5.4%, respectively, compared to comparative compositions. Thus, the improved glueability and bond strength results obtained using composition no. 13 of the present invention in EB quality were also confirmed for composition no. 14 of the present invention in BC quality.

[0211] The starch adhesive containing a combination of MFC and liquid sodium aluminate has therefore proven to enable the same production rate as the borax-containing reference adhesive in complex and heavy double-wall quality. Furthermore, the improved board properties and higher strength in difficult double-backer bonding demonstrate that better adhesive properties are achieved with the adhesive of the present invention compared to the borax-containing reference adhesive.

[0212] Example 5 Improvement of properties of PVA-containing adhesive compositions The compositions shown in Table 10 were prepared according to the following protocol. A reference (comparative composition) was prepared by adding PVA Glue One Bag Mix (Supermix glue containing boric acid, a commercially available powdered mixture as "Supermix" by Borregaard, with a PVA content of approximately 25%) to cold water while stirring. The mixture was heated to 96°C and stirred for 30 minutes. The concentration of boric acid in the final adhesive was 0.5%.

[0213] The adhesive of the present invention, comprising MFC and aluminum sulfate, is similarly prepared by first adding MFC, then aluminum sulfate, followed by water and Supermix glue without boric acid. The mixture is heated to 96°C and stirred for 30 minutes. In the examples, liquid aluminum sulfate (provided by Kemira, Al) is used. 3+ The following were used: a 4.2% Al2O3 content, an 8.1% Al2O3 content, or solid aluminum sulfate hydrate (Al2(SO4)3· x H2O, 7.9~9.4% Al, Sigma Aldrich) (Tables 10 and 12, respectively).

[0214] [Table 10]

[0215] The adhesive compositions listed in Table 10 were tested in the mass production of solid boards. During the tests, various quality papers were tested, and 4 to 5 sheets of paper were bonded together. The quality parameters of the solid boards produced in this way are summarized in Table 11.

[0216]

Table 11

[0217] As is clear from Table 11, the adhesive composition of the present invention brings about various improved effects that surpass the boric acid-containing adhesive composition, such as a 12% increase in burst strength, an 11% increase in ECT (edge wise crush resistance), a 19% decrease in deflection, and a 52% decrease in water absorption.

[0218] Furthermore, due to the significantly increased adhesiveness, the maximum operating speed was able to reach 144 m / min. The increase in adhesiveness is consistent with the initial tack measurement values shown below.

[0219] Also, the board was flatter than the reference board using the boric acid-containing adhesive composition. Therefore, more boards can then be stacked. Also, the solid board prepared using the adhesive composition of the present invention had a smoother cut edge. That is, after cutting, the edge had a smoothly sealed appearance.

[0220] Furthermore, the adhesive compositions shown in Table 12 were tested with respect to initial tack and water uptake rate.

[0221]

Table 12

[0222]

Table 13

[0223] The composition was prepared based on the following general protocol.

[0224] Composition No. 20 was prepared by adding boric acid-containing glue powder to cold water in a ratio of 1:2.33. The mixture was then stirred at 400 rpm using a dispersion blade until a satisfactory dispersion was achieved. The composition was then heated to 95°C in an oil bath and held there with continuous stirring for 10-20 minutes. After cooling, the glue was ready for use.

[0225] Composition No. 21 was prepared by first dispersing MFC in cold water and stirring the mixture at 400 rpm for 5 minutes using a dispersion blade. Next, Supermix glue powder (without boric acid) was added, and the mixture was stirred for a further 10 minutes. Finally, it was heated to 95°C and maintained at that temperature for 10-20 minutes while continuously stirring at 400 rpm.

[0226] To prepare the adhesive compositions of the present invention (compositions 17, 18, and 19), aluminum sulfate was introduced together with Supermix powder. Otherwise, the same procedure as that used to prepare composition No. 21 was used.

[0227] Composition No. 22 was prepared by adding glue powder (without boric acid) and aluminum sulfate to cold water. The mixture was then stirred at 400 rpm using a dispersion blade until a satisfactory dispersion was achieved. The mixture was then heated to 95°C in an oil bath and held there with continuous stirring for 10-20 minutes. After cooling, the glue was ready for use.

[0228] Initial tack was determined using a method based on ASTM D6195 Loop tack tests, and the test was performed on a texture analyzer (TA.XTplus, stable micro systems). Two sets of solid board strips were cut. One set consisted of an upper section of 175x25mm and a lower section of 90x25mm. The upper section was formed into a loop and mounted on the upper crosshead of the texture analyzer, and the lower section was bent so that it could be mounted on the lower clamp, and a 25x25mm surface was available for testing. 0.29±0.1g of glue was applied to the lower section. The complete setup for this measurement method is shown in Figure 1. The upper section was then brought closer to the lower section at a crosshead speed of 10mm / s to 35mm until the two sections were in complete contact. The contact was maintained for 15 seconds, and then the upper section was pulled up at the crosshead speed. A 5kg load cell was used. The force required to tear the paper was recorded and compared as a measure of initial wet tack.

[0229] To determine the water absorption rate, the adhesive was poured onto an aluminum pan and dried in a fan-operated furnace at 105°C for 24 hours. The dried film was weighed and placed in a glass container with distilled water. To measure the water absorption rate, the sample was removed from the water, the surface was carefully dried with a tissue, and then weighed again. The water absorption rate was calculated as shown in (Equation 1). [ka] In the above formula, mw and md are the masses of the wet and dry samples, respectively. Measurements were first taken every 20 minutes for 1 hour, then every hour for 4 hours, and finally, a final measurement was taken after 24 hours. The values ​​were stable in the final measurement.

[0230] The results of the initial tack are shown in Figures 2 and 3.

[0231] The results for water uptake rate are shown in Figure 4.

[0232] As is evident from the drawings, (reference) composition No. 20 (containing undesirable boric acid) exhibited the best initial tack. By substituting boric acid with MFC alone, the initial tack decreased by approximately 50% (composition No. 21), and by substituting boric acid with aluminum sulfate alone, the initial tack decreased by approximately 40% (composition No. 22). However, using a combination of MFC and aluminum sulfate significantly improves the initial tack compared to using MFC alone or aluminum sulfate alone. Using amounts of 0.2% MFC and 0.2% aluminum sulfate (0.1% anhydrous aluminum sulfate) (see composition 17), the initial tack is similar to that of the boric acid-containing adhesive composition.

[0233] Therefore, by using a combination of MFC and aluminum sulfate, boric acid in the adhesive PVA-based composition can be completely avoided without significantly degrading the tackiness of the composition.

[0234] Furthermore, as is clear from Figure 4, the boric acid-containing adhesive composition exhibits a fairly high water absorption rate. A high water absorption rate is generally undesirable because the solid board boxes to which such adhesives are applied are often used in high-humidity environments, such as in agriculture or for packaging seafood. However, by adding MFC to the composition, the water absorption rate can be reduced remarkably.

[0235] Overall, the combination of MFC and aluminum sulfate allows for the complete removal of boric acid from the adhesive composition, while simultaneously reducing water uptake and maintaining a nearly constant tackiness. The present invention includes the following embodiments: <Aspect 1> An adhesive composition, a) Microfibrillated cellulose and b) At least one metal in oxidation state II or higher, c) at least one compound that (a) is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and Includes, The relative amounts of at least one metal in oxidation state II or higher are as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.0005 to 5, preferably 0.001 to 1, more preferably 0.005 to 0.5, even more preferably 0.01 to 0.2, and even more preferably 0.02 to 0.1. (ii) (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, the molar amount of the metal in oxidation state II or higher relative to the dry mass kg of the at least one compound is 0.002 to 20, preferably 0.05 to 5, more preferably 0.08 to 2, even more preferably 0.1 to 1.5, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.001 to 3, preferably 0.05 to 2, more preferably 0.06 to 1.5, more preferably 0.1 to 1, and still more preferably 0.1 to 0.4. An adhesive composition that conforms to at least one of the following. <Aspect 2> The metal in oxidation state II or higher includes aluminum in oxidation state II or higher, calcium in oxidation state II or higher, zirconium in oxidation state II or higher, magnesium in oxidation state II or higher, zinc in oxidation state II or higher, hafnium in oxidation state II or higher, or titanium in oxidation state II or higher, or any combination thereof, preferably including aluminum in oxidation state II or higher. The adhesive composition according to Embodiment 1, wherein optionally the metal in oxidation state II or higher contains aluminum ions, and further optionally is derived from aluminum sulfate, sodium aluminate, or aluminum hydroxide. <Aspect 3> The adhesive composition according to embodiment 1 or 2, wherein the solvent is a protic solvent, and optionally the solvent contains water or consists of water. <Aspect 4> The adhesive composition according to any one of embodiments 1 to 3, wherein the microfibrillated cellulose has at least one length scale, i.e., fibril diameter and / or fibril length, and the length scale is reduced relative to the fibril diameter and / or fibril length of the nonfibrillated cellulose, and preferably the diameter of the microfibrillated cellulose fibrils forming the microfibrillated cellulose of the present invention is in the nanometer range, i.e., 1 nm to 1000 nm, preferably on average 10 nm to 500 nm. <Aspect 5> The amount of microfibrillated cellulose in the adhesive composition is 0.001 to 10 wt.% (w / w), preferably 0.01 to 5 wt.%, more preferably 0.01 to 1 wt.%, more preferably 0.01 to 0.5 wt.%, or more preferably 0.01 to 0.3 wt.%, based on the total weight of the adhesive composition. (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1 or 0.0005 to 0.03 or 0.001 to 0.01. The adhesive composition according to any one of embodiments 1 to 4. <Pattern 6> The adhesive composition according to any one of embodiments 1 to 5, wherein the solvent is present in an amount of 20 to 90 wt.%, preferably 30 to 80 wt.%, more preferably 40 to 80 wt.%, and even more preferably 50 to 80 wt.%, for example 65 to 80 wt.%, preferably 66 to 79 wt.%, based on the total weight of the adhesive composition. <Aspect 7> The adhesive composition according to any one of embodiments 1 to 6, wherein the composition does not contain or contains only trace amounts of a boron-containing crosslinking agent, preferably the adhesive composition does not contain or contains only trace amounts of borax and boric acid, and more preferably the adhesive composition does not contain or contains only trace amounts of boron. <Aspect 8> (a) polymerizable, or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher, the compound being one of the following compounds, i.e. At least one starch or starch derivative, at least one polyvinyl alcohol, at least one polyvinyl acetate, at least one polyethylene glycol, at least one polypropylene glycol, at least one polysaccharide, at least one carbohydrate, at least one polypeptide, at least one acrylate, at least one acrylamide, at least one ethylene oxide, at least one propylene oxide, at least one glycol, at least one polyether, at least one polyester, at least one polyol, at least one epoxy resin, at least one polyurethane, at least one polyacrylate, e.g., polymethyl methacrylate (PMMA), at least one polyurea, and at least one carbamide, or any combination thereof, Preferably selected from at least one starch or starch derivative and at least one polyvinyl alcohol. The adhesive composition according to any one of embodiments 1 to 7. <Pattern 9> The aforementioned metals in oxidation state II or higher are Al(OH) 4 - It exists as and / or is derived from sodium aluminate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one starch or starch derivative, and optionally, The amount of microfibrillated cellulose in the starch-based adhesive composition is 0.001 to 10 wt%, preferably 0.01 to 5 wt%, more preferably 0.01 to 1 wt%, more preferably 0.01 to 0.5 wt%, and / or 0.01 to 0.3 wt%, based on the total weight of the adhesive composition, and / or (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1, even more preferably 0.0005 to 0.03, and even more preferably 0.001 to 0.01. The adhesive composition according to any one of embodiments 1 to 8. <Aspect 10> The aforementioned metal in oxidation state II or higher is Al 3+ It exists as and / or is derived from aluminum sulfate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one polyvinyl alcohol (PVA), and optionally, The amount of microfibrillated cellulose in the PVA-based adhesive composition is 0.001 to 10 wt%, preferably 0.01 to 5 wt%, more preferably 0.015 to 1 wt%, more preferably 0.02 to 0.5 wt%, and more preferably 0.05 to 0.3 wt, based on the total weight of the adhesive composition, and / or (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.5, preferably 0.0002 to 0.3, more preferably 0.0004 to 0.2, even more preferably 0.0005 to 0.1, even more preferably 0.005 to 0.1, and even more preferably 0.008 to 0.08. The adhesive composition according to any one of embodiments 1 to 8. <Aspect 11> Use of an adhesive composition according to any one of embodiments 1 to 10 for manufacturing corrugated cardboard or solid board, optionally, (I) The use is for the purpose of manufacturing corrugated cardboard, and the metal in oxidation state II or higher is Al(OH) 4 - It exists as and / or is derived from sodium aluminate, and (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one starch or starch derivative, and the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher. (II) The use described above is for the purpose of manufacturing solid boards, and the metal in oxidation state II or higher is Al 3+ It exists as and / or is derived from aluminum sulfate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, preferably OH groups, wherein the compound is at least one polyvinyl alcohol, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher. Use of adhesive compositions. <Aspect 12> Use of the adhesive composition according to any one of the embodiments 1 to 10, as an adhesive, in a paint composition, as a film, as a (surface) sizing composition, as a composite or in a composite, as a resin, as a paste, as a food thickener or additive, in a gel, in a hydrogel, or as an adsorbent, or in an adhesive film, protective film, primer film, or surface sizing film. <Aspect 13> A corrugated cardboard or solid board comprising the adhesive composition described in any one of embodiments 1 to 10. <Aspect 14> A method for manufacturing corrugated cardboard, wherein the method comprises at least the following steps, i.e. a) Prepare an adhesive composition according to any one of the embodiments 1 to 10, b) Prepare flute core paper and liner paper for corrugated cardboard, and optionally, the flute paper or the liner paper or both are at least partially chemically treated or chemically treated. c) The adhesive composition is applied to at least a portion of the top of the flutes of the corrugated paper strip, on at least one side, preferably both sides, and d) Within the corrugator, at least one liner is attached to the corrugated paper piece, preferably an additional liner is attached to the other side of the corrugated paper piece, and e) Manufacture single, double, triple, or further multi-layer wallboards, preferably in a continuous process. A method for manufacturing corrugated cardboard, including the manufacturing process. <Aspect 15> Corrugated cardboard obtained or obtainable by the method described in Embodiment 14.

Claims

1. An adhesive composition, a) Microfibrillated cellulose and b) At least one metal in oxidation state II or higher, c) At least one compound that (a) is polymerizable or already partially or completely polymerized, and (b) has at least two groups available for hydrogen bonding, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, d) At least one solvent and Includes, The adhesive composition does not contain a boron-containing crosslinking agent. The relative amounts of at least one metal in oxidation state II or higher are as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.0005 to 5. (ii) (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, the molar amount of the metal in oxidation state II or higher relative to the dry mass kg of the at least one compound is 0.002 to 20, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.001 to 3. An adhesive composition that conforms to at least one of the following.

2. The relative amounts of at least one metal in oxidation state II or higher are as follows: (i) The molar amount of the metal in oxidation state II or higher relative to the total weight kg of the adhesive composition including the solvent is 0.01 to 0.

2. (ii) (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher, with respect to the dry mass kg of the at least one metal in oxidation state II or higher, the molar amount of the metal in oxidation state II or higher relative to the dry mass kg of the at least one metal is 0.08 to 2, or (iii) The metal in oxidation state II or higher is present as an oxide, hydroxide, or oxyhydroxide, or any mixture thereof, and the weight percentage of the oxide, hydroxide, or oxyhydroxide relative to the total weight of the composition including the solvent is 0.1 to 1. The adhesive composition according to claim 1, wherein it conforms to at least one of the following.

3. The metal in oxidation state II or higher includes aluminum in oxidation state II or higher, calcium in oxidation state II or higher, zirconium in oxidation state II or higher, magnesium in oxidation state II or higher, zinc in oxidation state II or higher, hafnium in oxidation state II or higher, or titanium in oxidation state II or higher, or any combination thereof. The adhesive composition according to claim 1 or 2.

4. The adhesive composition according to any one of claims 1 to 3, wherein the solvent is a protic solvent.

5. The adhesive composition according to any one of claims 1 to 4, wherein the microfibrillated cellulose has at least one length scale, i.e., fibril diameter and / or fibril length, and the length scale is reduced relative to the fibril diameter and / or fibril length of the nonfibrillated cellulose, and the diameter of the microfibrillated cellulose fibrils forming the microfibrillated cellulose of the present invention is in the nanometer range, i.e., 1 nm to 1000 nm.

6. The amount of microfibrillated cellulose in the adhesive composition is 0.001 to 10 wt.% (w / w) based on the total weight of the adhesive composition, or (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.

5. The adhesive composition according to any one of claims 1 to 5.

7. The amount of microfibrillated cellulose in the adhesive composition is 0.01 to 5 wt.% based on the total weight of the adhesive composition, or (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0005 to 0.

1. The adhesive composition according to any one of claims 1 to 6.

8. The adhesive composition according to any one of claims 1 to 7, wherein the solvent is present in an amount of 20 to 90 wt.% based on the total weight of the adhesive composition.

9. The adhesive composition according to any one of claims 1 to 8, wherein the solvent is present in an amount of 50 to 80 wt.% based on the total weight of the adhesive composition.

10. The adhesive composition according to any one of claims 1 to 9, wherein the adhesive composition does not contain borax and boric acid.

11. (a) polymerizable, or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher, the compound being one of the following compounds, i.e. At least one starch or starch derivative, at least one polyvinyl alcohol, at least one polyvinyl acetate, at least one polyethylene glycol, at least one polypropylene glycol, at least one polysaccharide, at least one carbohydrate, at least one polypeptide, at least one acrylate, at least one acrylamide, at least one ethylene oxide, at least one propylene oxide, at least one glycol, at least one polyether, at least one polyester, at least one polyol, at least one epoxy resin, at least one polyurethane, at least one polyacrylate, e.g., polymethyl methacrylate (PMMA), at least one polyurea, and at least one carbamide, or any combination thereof, The adhesive composition according to any one of claims 1 to 10.

12. The aforementioned metals in oxidation state II or higher are Al(OH) ４ － It exists as and / or is derived from sodium aluminate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the compound is at least one starch or starch derivative, and the groups can crosslink with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher. The adhesive composition according to any one of claims 1 to 11.

13. The amount of microfibrillated cellulose in the starch-based adhesive composition is 0.001 to 10 wt% based on the total weight of the adhesive composition, and / or (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.

5. The adhesive composition according to claim 12.

14. The aforementioned metal in oxidation state II or higher is Al ３＋ It exists as and / or is derived from aluminum sulfate, and, (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the compound is at least one polyvinyl alcohol (PVA), the groups being able to crosslink with at least one functional group of the microfibrillated cellulose and / or at least one metal in oxidation state II or higher. The adhesive composition according to any one of claims 1 to 11.

15. The amount of microfibrillated cellulose in the PVA-based adhesive composition is 0.001 to 10 wt% based on the total weight of the adhesive composition, and / or (a) polymerizable or already partially or completely polymerized, and (b) having at least two groups available for hydrogen bonding, wherein the weight ratio of the microfibrillated cellulose to the at least one compound that can crosslink the groups with at least one functional group of the microfibrillated cellulose and / or the at least one metal in oxidation state II or higher is 0.0001 to 0.

5. The adhesive composition according to claim 14.

16. Use of the adhesive composition according to any one of claims 1 to 15 for manufacturing corrugated cardboard or solid board.

17. Use of the adhesive composition according to any one of claims 1 to 15, as an adhesive, in a paint composition, as a coating, as a (surface) sizing composition, in a composite, as a resin, as a paste, in a gel, in a hydrogel, in an adhesive coating, in a protective coating, in a primer coating, or in a surface sizing coating.

18. A corrugated cardboard or solid board comprising the adhesive composition according to any one of claims 1 to 15.

19. A method for manufacturing corrugated cardboard, wherein the method comprises at least the following steps, i.e. a) Prepare the adhesive composition according to any one of claims 1 to 15, b) Prepare the core paper and liner paper for the cardboard flute, c) The adhesive composition is applied to at least a portion of the top of the flutes of the corrugated paper strip, on at least one side, and d) In the corrugator, at least one liner is attached to the corrugated paper strip, and e) Manufacture single, double, triple, or further multi-layer wallboards. A method for manufacturing corrugated cardboard, including the manufacturing process.

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