Coating for reducing the oil absorbency of a cellulose-based web

Abstract

A method for reducing surface oil absorption of a cellulose-based substrate is provided, wherein a coating composition is applied to the substrate, wherein the coating composition comprises carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC). Coated paperboard and laminates of the coated paperboard with a polymer layer are also provided. The coating composition provides improved surface oil absorption and improved adhesion of an overlying polymer layer.

Description

Technical Field

[0001] The present invention relates to a thin bio-based coating that reduces the oil absorbency of rough cellulose substrates such as paperboard.

Background Art

[0002] One problem associated with rough substrates such as uncoated paperboard is that they have a relatively high absorbency for low-polarity or non-polar liquids such as oil or UV ink. Lower absorbency would be desirable, for example, in printing. With lower absorbency, in printing, ink uptake can be reduced and curing can be accelerated. This property is required not only for paper or paperboard but also for their various laminates. For example, when laminating with polyethylene, it is very important that the treatment layer does not adversely affect the adhesion of the applied polymer layer.

[0003] Reduction of oil absorbency is an essential property in many food packaging applications, including both various wrapping papers and paperboards. Many synthetic chemicals or polymers used for oil repellency are toxic, cause problems during recycling and reuse, or may interfere with other chemicals when applied as a coating. Traditionally, fluorochemicals have been used to provide good barrier properties against oil and grease.

[0004] Moreover, many barrier chemicals can further cause thermoplastic behavior, which can result in deposits when breaking down broke (waste paper). Latex binders and dispersion barriers are known to not only increase the reject rate but also increase the risk of deposits on the paper machine.

[0005] One solution to the above problem would be a coating with good oil barrier properties such as PVOH. However, problems associated with such polymers are that they often cause blistering during drying and require additional special processing equipment in the plant. Their viscosity and rheology properties also strongly depend on temperature and consistency.

[0006] Today, paperboard is often surface sized with starch. Some modified starches may reduce oil absorbency, but generally do not provide a synergistic effect with the applied liquid and gas barrier layers.

Summary of the Invention

Problems to be Solved by the Invention

[0007] There is still a need for novel coatings and coating methods for cellulose-based substrates such as paperboard that exhibit reduced oil absorbency.

Means for Solving the Problems

[0008] Accordingly, a method for reducing surface oil absorption of a cellulose-based substrate is provided, where a coating composition is applied to the cellulose-based substrate, and the coating composition includes carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC). Also provided are a coated cellulose-based substrate, and a laminate (laminated body) of the coated paperboard and a polymer layer. The coating composition provides improved (i.e., reduced) surface oil absorbency while maintaining the adhesiveness of the polymer layer applied thereon.

[0009] Additional details of the invention are set forth in the dependent claims. One aspect of the present invention is shown below, but the present invention is not limited thereto. [Invention 1] A method for reducing the surface oil absorption of a cellulose-based substrate, the method comprising: applying a coating composition to at least one surface of the cellulose-based substrate, wherein the coating composition comprises carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC), and drying the coating composition to form a barrier layer on the cellulose-based substrate, wherein the CMC has a degree of substitution (DS) of 0.05 to 0.5, and the coating composition further comprises an organic acid, preferably an organic polyacid, and / or a metal salt of an organic acid or organic polyacid, the method comprising. [Invention 2] The method according to Invention 1, wherein the CMC has a degree of substitution (DS) of 0.1 to 0.3. [Invention 3] The method according to Invention 1 or 2, wherein before application of the coating composition, the cellulose-based substrate is a paperboard such as uncoated paperboard, surface-sized paperboard, paperboard containing pigments, or paperboard coated with a single mineral, preferably uncoated paperboard. [Invention 4] The method according to any one of Inventions 1 to 3, wherein the coating composition comprises CMC and / or a salt of CMC at a concentration of 1 to 100% by weight, preferably 10 to 90% by weight, more preferably 30 to 90% by weight. [Invention 5] The method according to any one of Inventions 1 to 4, wherein the CMC has a salt content of more than 1% by weight, preferably more than 2% by weight, more preferably more than 5% by weight. [Invention 6] The method according to any one of Inventions 1 to 5, wherein the organic acid is selected from citric acid, lactic acid, acetic acid, formic acid, oxalic acid, 1,2,3,4-butanetetracarboxylic acid, malonic acid or tartaric acid, uric acid, or malic acid, preferably citric acid. [Invention 7] The method according to any one of Inventions 1 to 6, wherein the coating composition is a buffered aqueous solution comprising an organic acid, preferably an organic polyacid, and a metal salt of the organic acid. [Invention 8] The method according to any one of Inventions 1 to 7, wherein the coating composition has a pH between 3 and 7, preferably between 3 and 5. [Invention 9] The method according to any one of Inventions 1 to 8, wherein the coating composition is an aqueous solution of CMC. [Invention 10] The method according to any one of Inventions 1 to 9, wherein the coating composition contains one or more fillers such as one or more nanofillers, preferably in an amount in the range of 1 to 50% by weight. [Invention 11] The method according to any one of Inventions 1 to 10, wherein the coating composition is applied in an amount of 0.5 to 10 gsm, preferably in an amount of 1 to 5 gsm, more preferably in an amount of about 2 gsm. [Invention 12] The method according to any one of Inventions 1 to 11, wherein the coating composition further contains one or more cellulose derivatives such as hydroxyethyl cellulose (HEC), ethyl hydroxyethyl cellulose (EHEC) or methyl cellulose. [Invention 13] The method according to any one of Inventions 1 to 12, further comprising the step of applying a thermoplastic polymer to the barrier layer (single layer or multilayer) to form a laminate comprising the coated paperboard and the thermoplastic polymer layer. [Invention 14] The method according to Invention 13, wherein the thermoplastic polymer is selected from polyethylene, polylactic acid, poly(glycolic acid), polypropylene, thermoplastic starch, ethylene vinyl alcohol, thermoplastic cellulose derivatives, or blends or copolymers thereof. [Invention 15] The method according to any one of Inventions 1 to 14, wherein the cellulose-based substrate has a Parker Print-Surf (PPS) smoothness greater than 1, preferably greater than 3, more preferably greater than 5, but less than 50 μm when measured at 1.0 MPa in accordance with ISO 8791-4 before application of the coating composition. [Invention 16] The cellulose-based substrate has a Cobb-Unger value (30 seconds, back side) of at least 20 g / m 2 before application of the coating composition and a Cobb-Unger value (30 seconds, back side) of less than 5 g / m 2 after application of the coating composition, where the Cobb-Unger value is a measure of oil absorption and is measured by the SCAN-P 37:77 (30 seconds) method. The method according to any one of Inventions 1 to 15. [Invention 17] A coated substrate comprising a layer of a cellulose-based substrate and at least one barrier layer comprising carboxymethylcellulose (CMC) and / or a salt of carboxymethylcellulose (CMC), wherein the CMC has a degree of substitution (DS) of 0.05 to 0.5, and the barrier layer further comprises an organic acid, preferably an organic polyacid, and / or a metal salt of an organic acid or organic polyacid. [Invention 18] The coated substrate according to Invention 17, wherein the organic acid is selected from citric acid, lactic acid, acetic acid, formic acid, oxalic acid, 1,2,3,4-butanetetracarboxylic acid, malonic acid or tartaric acid, uric acid, or malic acid, preferably citric acid. [Invention 19] The coated substrate according to Invention 17 or 18, wherein the barrier layer comprises one or more fillers such as one or more nanofillers, suitably in an amount in the range of 1 to 50% by weight. [Invention 20] The coated substrate according to any one of Inventions 17 to 19, wherein the CMC has a degree of substitution (DS) of 0.1 to 0.3. [Invention 21] The coated substrate according to any one of Inventions 17 to 20, wherein, prior to application of the coating composition, the cellulose-based substrate is paperboard such as uncoated paperboard, surface-sized paperboard, paperboard containing pigments, or paperboard coated with a single mineral, preferably uncoated paperboard. [Invention 22] A laminate comprising the coated substrate according to any one of Inventions 17 to 21, further comprising a thermoplastic polymer layer disposed on the surface of the barrier layer (single layer or multilayer) on the opposite side of the cellulose-based substrate. [Invention 23] The laminate according to Invention 22, wherein the thermoplastic polymer is selected from polyethylene, polylactic acid, poly(glycolic acid), polypropylene, thermoplastic starch, or blends or copolymers thereof. [Invention 24] The laminate according to Invention 22 or 23, wherein, prior to application of the coating composition, the cellulose-based substrate is paperboard such as uncoated paperboard, surface-sized paperboard, paperboard containing pigments, or paperboard coated with a single mineral, preferably uncoated paperboard.

Mode for Carrying Out the Invention

[0010] Detailed Description of the Invention Accordingly, a method for reducing the surface oil absorption of a cellulose-based substrate, such as paperboard, typically uncoated paperboard, is provided. Generally, the method includes applying a coating composition to at least one surface of the cellulose-based substrate, where the coating composition includes carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC), and the method also includes drying the coating composition to form a barrier layer on the cellulose-based substrate.

[0011] Also provided is a coated substrate including a layer of a cellulose-based substrate and at least one barrier layer including carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC).

[0012] For example, many packaged foods, such as pizza boxes, hamburger boxes, cereals, etc., contain fat. Accordingly, the present invention is mainly related to oils and greases that are derived from food and may migrate through paperboard. This oil may also be a residual oil component in recycled fibers, and thus, the present technology will also reduce the migration of those components.

[0013] Furthermore, printing inks usually contain oils and volatile organic components, which are considered harmful if they migrate to food. This technology can provide an improved barrier against such migration. Since the present invention reduces oil absorbency, faster ink drying and less ink usage are possible. Thus, this technology can provide better printing when using, for example, not only oil-based inks but also UV-based inks and varnishes.

[0014] Many oil barriers for packaged foods are coated with latex-based coatings. This technology makes it possible to replace petroleum-derived coatings with bio-based coatings.

[0015] Cellulose-based substrate This technology is applied to cellulose-based substrates such as wrapping paper or cardboard. Cardboard is generally known as "card" or "cardboard". Cardboard usually has a basis weight exceeding 190 g / m 2 . It may be single-layer or multi-layer.

[0016] One parameter that is of interest for cellulose-based substrates is the PPS (Parker Print-Surf) smoothness measured according to ISO 8791-4. This is a measure of the roughness of the cellulose-based substrate and is important for subsequent printing or lamination processes. Thus, the cellulose-based substrate may have a PPS (Parker Print-Surf) smoothness greater than 1 (μm), preferably greater than 3 (μm), more preferably greater than 5 (μm), but less than 50 μm when measured at 1.0 MPa before applying the coating composition. Although PPS describes the roughness of the substrate, this is also an important property when considering conversion applications such as printing or coating. A less rough surface gives better printing and appearance, but if the surface is too dense and smooth, it may not necessarily accept sufficient coating liquid (when using the contact coating method).

[0017] Another parameter of interest is the oil absorption. In the present technology, the oil absorption is measured by the SCAN-P 37:77 (30 seconds) method, whereby the "Cobb-Unger value" is obtained in g / m 2 units. Before applying the coating composition, the cellulose-based substrate has a relatively high oil absorption defined by a Cobb-Unger value of at least 20 g / m measured after 30 seconds on the back side (bs). It should be understood that various fibers and fiber mixtures can be utilized. Of course, using very fine purified pulp may improve smoothness. Also, adding chemicals to the finished furnish may change the Cobb-Unger value. 2

[0018] The paperboard used in this specification is a base board for liquid paperboard, but the present invention is not limited to such paperboard grades. The paperboard can also be used for cup stock and other food packaging applications. The paperboard may be uncoated paperboard, surface-sized paperboard, paperboard containing pigments (colored paperboard), or paperboard coated with a single mineral, and is preferably uncoated paperboard.

[0019] Coating composition The coating composition contains carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC). CMC is a cellulose derivative in which a carboxymethyl group (-CH2-COOH) is bonded to a part of the hydroxyl groups of glucopyranose monomers constituting the cellulose backbone. The coating composition may contain CMC and / or a salt of CMC at a concentration of 1 to 100% by weight, preferably 10 to 90% by weight, more preferably 30 to 90% by weight. The coating composition is usually an aqueous solution of CMC.

[0020] One parameter of interest is the degree of substitution, i.e., the extent to which the cellulose is derivatized. CMC according to one embodiment has a degree of substitution (DS) of 0.05 to 0.5, preferably 0.1 to 0.3. When the degree of substitution is low, the adhesion of the upper thermoplastic layer is improved and the Cobb-Unger value is improved. Usually, the degree of substitution (DS) is measured by titration methods as disclosed, for example, in Ambjornsson et al., (2013), Bioresources, 8(2), 1918-1932. It should be understood that since factors such as salt content affect the titration results, the DS needs to be tested for the blank and the washed product. Without being bound by theory, due to the characteristic fiber and fibril structure, CMC with a low DS is thought to provide better hold-out and thus a more effective protective coating. A better "hold-out" means that the coating stays better on the surface, and thus a more effective coating can be achieved with a lower coating weight.

[0021] Another parameter of interest is the salt content. "Technical grades" of CMC have a salt content exceeding 5%, and in some cases may have a salt content of 30 - 40%. According to the present invention, the CMC has a salt content exceeding 1 wt%, preferably exceeding 2 wt%, more preferably exceeding 5 wt%. High-purity grade CMC is often more viscous and expensive. In this case, a good barrier was achieved despite the fact that the salt content was high. The salt may be residual salt from the carboxymethylation process or may be added salt. The salt can be a monovalent, divalent or trivalent metal salt and / or cation such as a Na-, Ca-, Mg- or Al-salt.

[0022] The coating composition may further contain an organic acid, preferably an organic polyacid; and / or a metal salt of an organic acid or an organic polyacid. Suitable organic acids are selected from citric acid, lactic acid, acetic acid, formic acid, oxalic acid, 1,2,3,4-butanetetracarboxylic acid, malonic acid or tartaric acid, uric acid, or malic acid, preferably citric acid. By using an organic acid, it becomes possible to adjust the pH of the coating composition as needed. In particular, the coating composition can be a buffered aqueous solution containing an organic acid, preferably an organic polyacid, and a metal salt of the organic acid. The coating composition suitably has a pH between 3 and 7, preferably between 3 and 5. Organic acids such as citric acid function as cross-linking agents for CMC. Preferably, the dried low-DS CMC is first dispersed in a solution containing citric acid, typically a solution containing 1 to 60 wt% citric acid.

[0023] In particular, for example, in order to obtain a synergistic effect such as moisture resistance (water resistance), the optimal pH is between 3 and 5, and is considered to be about 4, for example. Conventionally, it has been understood that when the pH is below 3, sodium CMC in the solution may be protonated and CMC may precipitate. Also, a low pH is a safety risk and may increase the risk of corrosion. At low pH, especially when the storage time is long at a higher temperature, polymer degradation begins and CMC loses some of its physicochemical properties. However, it has been found that low-DS CMC grades are much less affected by pH and should be more thermally stable. This also makes it possible to store the suspension at a lower pH under mill conditions without significantly changing the rheological properties. In the case of high-DS CMC grades, a very low pH causes an undesirable increase in the viscosity of the described coating composition. Thus, and counterintuitively, a lower pH simultaneously allows for a lower viscosity of the coating composition. Since the viscosity is kept low, this allows for a higher solids content in the coating composition.

[0024] A preferred coating process for the coating composition is a roll or jet applicator combined with a blade unit. Also, other coating devices such as roll coaters, curtain coaters, spray coaters, film presses, cast coaters, transfer coaters, gate roll size presses, air knives, etc. can be used. There are various versions of blade coaters, and the present technology is not limited to the type of blade coater. With the optimal viscosity (especially the optimal viscosity of compositions containing low DS CMC), coating can be applied using printing machines such as offset, gravure, reverse gravure, flexogravure, inkjet, etc. The coating composition can be applied to a cellulose-based substrate in an amount of 0.5 to 10 gsm, preferably 1 to 5 gsm, more preferably about 2 gsm. In the examples of the present application, the coating composition was applied in an amount of about 2 gsm based on gravimetric analysis.

[0025] The coating is applied in a single layer or multiple layers. The number of layers applied is usually determined by the thickness and quality of the coating layer. Thus, according to the present method, the step of applying the coating composition is repeated two or more times, resulting in the formation of two or more, for example, 2, 3, 4, 5 or 10 barrier layers. The coating can be prepared as wet-on-wet or with intermediate drying. It is also possible to combine one or more methods. The coating can be applied on one or both sides of the substrate.

[0026] Preferably, the coating is applied on a dry substrate having a dry content of more than 70 wt%, and more preferably more than 80 wt%, most preferably more than 85 wt%. The coating can also be carried out, for example, as a pre-coating or intermediate layer coating for mineral or dispersion barrier coatings. After application of the coating composition, the cellulose-based substrate usually has a Cobb-Unger value of less than 5 g / m 2 measured on the back side (bs) after 30 seconds.

[0027] The coating composition may also contain one or more cellulose derivatives such as CMC, hydroxyethyl cellulose (HEC), ethyl hydroxyethyl cellulose (EHEC) or methyl cellulose. In other words, it encompasses mixtures of such cellulose derivatives (e.g., those having a higher DS) and CMC having a lower DS.

[0028] Another feature of the present invention is that a low pH formulation can preferably be prepared by adding dry or substantially dry CMC or low CMC powder (solids content > 80%) to a solution containing an organic acid preferably disclosed herein, preferably at least 1% by weight of the organic acid. The preferred temperature is 10 - 90°C, preferably 15 - 80°C, more preferably 20 - 70°C. Also, without being bound by theory, the solution is considered to have high storage stability and be less susceptible to microbial attack.

[0029] The mixing of CMC and the organic acid can be carried out using conventional or high-shear mixing units including, for example, microfluidizers, (high-pressure) homogenizers, rotor-stator mixers, in-water counter collisions, steam explosions, or high-shear treatments in the presence of steam such as jet cookers. The mixing and homogenization can also be carried out in one or several steps including one or several processing methods. The temperature of the mixing and homogenization can vary depending on the process method. The mixing and homogenization can also be carried out together with one or several types of additives used in the formulation, including pigments or nanofillers.

[0030] Other components of the coating composition To adjust the processability and performance of the coating, various additives can be used, such as dispersants, crosslinking agents, lubricants, colorants, fillers, adhesion promoters, etc. Typical dispersants are, for example, polysaccharides and various gums, polyacrylic acid, etc., and are usually nonionic or anionic. Preferred components are processed starches such as anionic starch, hydroxypropylated starch, or anionic cellulose derivatives such as sodium carboxymethyl cellulose having a DS higher than 0.4, preferably higher than 0.5.

[0031] Typical nanofillers can be nanoclay, kaolin, bentonite, silica or silicate, titanium dioxide, calcium carbonate, talcum, etc. Most preferred is kaolin. Preferably, at least a part of the filler is a plate-like filler. Preferably, one dimension of the filler should have an average thickness or length of 1 nm to 10 μm. The mean average thickness D90 is within a given size range. The particle size of the mineral can be measured, for example, by laser scattering techniques. Thus, the barrier layer preferably contains one or more fillers, such as one or more nanofillers, in an amount in the range of 1 to 50% by weight. The one or more fillers can be selected from one or more of nanoclay, kaolin, bentonite, silica or silicate, titanium dioxide, calcium carbonate and talcum, and is preferably kaolin.

[0032] Lubricants such as calcium stearate, polyethylene emulsion, various triglycerides, glycerol or polyethylene glycol can also be included. In this context, lubrication means imparting fluidity in coating operations such as blade coating or spraying.

[0033] Laminate The technology also provides a laminate (laminated body) including the coated paperboard (board) described herein, and further including a thermoplastic polymer layer disposed on the surface of the barrier layer (single layer or multi-layer) on the opposite side of the cellulose-based substrate.

[0034] Accordingly, the method described herein may further include the step of applying a thermoplastic polymer to the barrier layer (single layer or multi-layer) to form a laminate including the coated paperboard (board) and the thermoplastic polymer layer described herein.

[0035] The thermoplastic polymer may be selected from polyethylene, polylactic acid, poly(glycolic acid), polypropylene, thermoplastic starch, ethyl vinyl alcohol (EVA), thermoplastic cellulose derivatives, or blends or copolymers thereof. The step of applying the thermoplastic polymer to the barrier layer (single layer or multi-layer) may be repeated two or more times so that two or more layers, such as 4 to 6 layers or 2 to 4 layers, for example, 2, 3, 4, 5, or 10 layers of thermoplastic polymer layers are formed.

[0036] When the laminate includes multiple layers of thermoplastic polymer, they are generally of different compositions, for example, different polymers. Two polymers can be "different" in terms of their physical properties (e.g., average MW) or their chemical structures (e.g., composite monomers).

[0037] Generally, the application of the thermoplastic polymer to the underlying layer (single layer or multi-layer) is carried out by extrusion, but other methods are also possible.

[0038] The surface strength is significantly improved by the CMC coating. During laminate formation, the CMC coating may actually increase the adhesion of the polymer layer compared to a laminate without the CMC coating.

Examples

[0039] The formulation of each coating is shown in Table 1.

[0040] "Reference" indicates uncoated paperboard. In the experiment, 247 gsm uncoated paperboard was used as the base paperboard.

[0041] All coating tests were conducted under the same settings. A roll applicator and a blade coating unit were used in the coating tests, and the test was performed three times between the same stations while the samples were being interim dried. The coating was dried with IR and hot air targeting a final moisture content of 6 - 7 wt%.

[0042] El represents Test 1 in which a CMC SG025 solution corresponding to low-substituted NaCMC dispersed at a concentration of 4.8 wt% in a citric acid solution was used. This solution was homogenized under high pressure to ensure the uniformity and disintegration of undissolved NaCMC. The degree of substitution was 0.25.

[0043] E2 represents the corresponding solution containing 7 wt% of plate kaolin (Barrisurf LC, Imerys) and 3 wt% of nanoclay (Cloisite Na+, BYK) calculated based on the dry weight of NaCMC.

[0044] E3 is similar to E2 but does not contain plate kaolin pigment.

[0045] Cl is similar to E2 but contains NaCMC with a degree of substitution of approximately 0.5, which means it dissolves in water. Only this sample was dispersed in tap water and decomposed using a high-shear mixer.

[0046] C2 is based on NaCMC with an even higher degree of substitution, namely 0.75. Its formulation was prepared in the same way as Cl.

[0047] C3 is an example based on a mixture of low DS CMC (used in El) and PVOH (Exceval AQ4101, Kuraray). This PVOH was a modified PVOH cooked at 90 - 95 °C for about 2 hours.

[0048]

Table 1

[0049] The results of the physical property tests are also shown in Table 1. Both samples E1 and E2 have low Cobb Unger values and good PE adhesiveness.

Claims

1. A method for reducing the surface oil absorption of a cellulose-based substrate, the method comprising: applying a coating composition to at least one surface of the cellulose-based substrate, wherein the coating composition comprises carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC); and drying the coating composition to form a barrier layer on the cellulose-based substrate, wherein the CMC has a degree of substitution (DS) of 0.05 to 0.5, and the coating composition further comprises an organic acid and / or a metal salt of an organic acid. The method, wherein the organic acid is selected from citric acid, lactic acid, acetic acid, formic acid, oxalic acid, 1,2,3,4-butanetetracarboxylic acid, malonic acid, tartaric acid, uric acid, or malic acid.

2. The method according to claim 1, wherein the CMC has a degree of substitution (DS) of 0.1 to 0.

3.

3. The method according to claim 1 or 2, wherein the cellulose-based substrate is paperboard before application of the coating composition.

4. The method according to any one of claims 1 to 3, wherein the coating composition comprises CMC and / or a salt of CMC at a concentration of 10 to 90% by weight.

5. The method according to any one of claims 1 to 4, wherein the CMC has a salt content of more than 1% by weight.

6. The method according to any one of claims 1 to 5, wherein the organic acid is citric acid.

7. The method according to any one of claims 1 to 6, wherein the coating composition is a buffered aqueous solution comprising an organic acid and a metal salt of the organic acid.

8. The method according to any one of claims 1 to 7, wherein the coating composition has a pH between 3 and 7.

9. The method according to any one of claims 1 to 8, wherein the coating composition is an aqueous solution of CMC.

10. The method according to any one of claims 1 to 9, wherein the coating composition comprises one or more fillers, suitably in an amount in the range of 1 to 50% by weight.

11. The method according to any one of claims 1 to 10, wherein the coating composition is applied in an amount of 0.5 to 10 gsm.

12. The method according to any one of claims 1 to 11, wherein the coating composition further comprises one or more cellulose derivatives. ​ ​ ​

13. The method according to any one of claims 1 to 12, further comprising the step of applying a thermoplastic polymer to the barrier layer (single or multi-layer) to form a laminate comprising a coated paperboard and a thermoplastic polymer layer.

14. The method according to claim 13, wherein the thermoplastic polymer is selected from polyethylene, polylactic acid, poly(glycolic acid), polypropylene, thermoplastic starch, ethylene vinyl alcohol, thermoplastic cellulose derivatives, or blends or copolymers thereof.

15. The method according to any one of claims 1 to 14, wherein the cellulose-based substrate has a PPS (Parker Print-Surf) smoothness greater than 1 but less than 50 μm when measured at 1.0 MPa prior to application of the coating composition.

16. The cellulose-based substrate has a Cobb-Unger value (30 seconds, back side) of at least 20 g / m ２ before application of the coating composition and has a Cobb-Unger value (30 seconds, back side) of less than 5 g / m ２ after application of the coating composition, where the Cobb-Unger value is a measure of oil absorption and is measured by the SCAN-P 37:77 (30 seconds) method, the method according to any one of claims 1 to 15.

17. A coated substrate comprising a layer of a cellulose-based substrate and at least one barrier layer comprising carboxymethyl cellulose (CMC) and / or a salt of carboxymethyl cellulose (CMC), wherein the CMC has a degree of substitution (DS) of 0.05 to 0.5, and the barrier layer further comprises an organic acid and / or a metal salt of an organic acid, wherein the organic acid is selected from citric acid, lactic acid, acetic acid, formic acid, oxalic acid, 1,2,3,4-butanetetracarboxylic acid, malonic acid or tartaric acid, uric acid, or malic acid, Coated substrate.

18. The coated substrate according to claim 17, wherein the organic acid is citric acid.

19. The coated substrate according to claim 17 or 18, wherein the barrier layer comprises one or more fillers, suitably in an amount in the range of 1 to 50% by weight.

20. The coated substrate according to any one of claims 17 to 19, wherein the CMC has a degree of substitution (DS) of 0.1 to 0.

3.

21. The coated substrate according to any one of claims 17 to 20, wherein the cellulose-based substrate is paperboard.

22. A laminate comprising the coated substrate according to any one of claims 17 to 21 and further comprising a thermoplastic polymer layer disposed on the surface of the barrier layer (single or multi-layer) on the opposite side of the cellulose-based substrate.

23. The laminate according to claim 22, wherein the thermoplastic polymer layer comprises a thermoplastic polymer selected from polyethylene, polylactic acid, poly(glycolic acid), polypropylene, thermoplastic starch, or a blend or copolymer thereof.

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