Method for coating a fiber web and surface-coated fiber web

Abstract

A method for coating a fibrous web, particularly a fibrous web comprising nanocellulose fibers, is provided. The method includes applying a coating to a textured surface region of a textured substrate, attaching a fibrous furnish or a wet fibrous web to the coated textured surface region of the textured substrate and optionally dewatering to provide a wet fibrous web, and drying the wet fibrous web such that at least a portion of the coating is transferred to the fibrous web. The method provides a coated fibrous web with improved barrier properties.

Description

Technical Field

[0001] A method for coating a fibrous web, particularly a fibrous web containing nanocellulose fibers, is provided. The method provides a coated fibrous web.

Background Art

[0002] Most coatings and surface treatments of fibrous webs, such as various coatings made by blade coating, film pressing and size pressing, or printing, and other contact and non-contact deposition techniques, are carried out on dry fibrous webs.

[0003] Conventionally, most coating methods for paper and paperboard aim to improve optical and printing properties, but barrier properties are not considered. In order to obtain an effective gas / aroma and / or grease barrier, it is essential that the coating is uniform and thick enough to provide a coating or barrier without pinholes.

[0004] One of the problems in techniques carried out on dry fibrous webs is that the dimensional stability and coating quality depend greatly on the interaction between the base substrate and the coating because the surface is re-wetted by the surface treatment. This is particularly a problem in hydrophilic substrates such as cellulose-based substrates where, due to both hydrophilicity and porosity, a lot of water or liquid uptake occurs during the application and leveling of coatings, which are usually water- or aqueous-based.

[0005] Another problem is that the coating is mainly carried out to adjust the appearance or the performance of the final product, for example, not for improving the web manufacturing process (online coating imposes additional requirements on the technical properties of the web, for example, to avoid web breakage). Another problem is that introducing a small amount of chemicals into thin fibrous webs such as cellulose films or greaseproof papers can be very difficult in terms of producing a uniform coating due to the aforementioned problems.

Summary of the Invention

[0006] A method for coating a fiber web, comprising: a. providing a textured substrate having at least one textured surface area; b. applying a coating agent to the textured surface area of the textured substrate to provide a coated textured surface area of the textured substrate; c. applying a fiber furnish to the coated textured surface area of the textured substrate, dewatering the fiber furnish to provide a wet fiber web, or d. attaching a wet fiber web to the coated textured surface area of the textured substrate; e. drying the wet fiber web obtained in step c or step d such that at least a portion of the coating agent migrates to the fiber web; and f. removing the coated fiber web from the textured surface area, thereby providing a coated fiber web.

[0007] Additional aspects of the technology are set forth in the following claims and description.

Brief Description of the Drawings

[0008]

Figure 1

Detailed Description of the Invention

[0009] A general method for coating a fiber web, comprising: a. Providing a textured substrate having at least one textured surface area; b. Applying a coating agent to the textured surface area of the textured substrate to provide a coated textured surface area of the textured substrate; c. Applying a fiber furnish to the coated textured surface area of the textured substrate and dewatering the fiber furnish to provide a wet fiber web, or d. Attaching a wet fiber web to the coated textured surface area of the textured substrate; e. Drying the wet fiber web obtained in step c or step d such that at least a portion of the coating agent migrates to the fiber web, and f. Removing the coated fiber web from the textured surface area, thereby providing a coated fiber web. A method is provided that includes these steps.

[0010] Possible advantages obtainable with the current technology include the following. - Online coating, single-layer or multi-layer coating; When using two or more types of textured substrates in sequence, it is possible to apply several types of coating agents. - Control of adhesion in the textured surface area of the textured substrate (control of dimensional stability, shrinkage) - Thin coatings (e.g., 0.1 - 100 gsm, preferably 0.3 - 50 gsm, more preferably 0.5 - 20 gsm in dry weight) - Extended nip; that is, when using this method, the contact time between the coating and the fiber web is increased. The contact time is preferably longer than that typically used in conventional coatings. - Improvement of barrier properties; that is, at least one of a gas barrier, a water vapor barrier, an aroma barrier, or an oil and grease barrier - Adjusted homogeneous or inhomogeneous (non-uniform) coating on one side of the fiber web

[0011] A texture substrate, which is preferably a texture belt or a texture cylinder, is provided. By using the texture substrate, the amount of coating can be controlled more accurately without problems associated with excessive coating liquid in a nip or the like. The use of the texture substrate brings further advantages such as improved profile control (in the machine direction) and the ability to create a texture pattern on the receiving web. The texture substrate has at least one texture surface area.

[0012] In the present technology, the term "texture substrate" means that the surface area of the substrate has a predetermined texture (i.e., is a texture surface). The texture of the texture surface area is not random and is thus distinguished from a surface / surface area / substrate that can be processed by grinding or another method to obtain a substantially random texture. Preferably, the texture surface area has a predetermined repeating texture in which the pattern is regularly repeated. The texture surface area can include the entire surface of the substrate, for example, the full width of the substrate in the cross-machine direction and / or the full length in the machine direction. Alternatively, the texture surface area can include only a part of the surface of the substrate, and other non-textured surface areas can be present intermittently, for example, at the ends of the substrate in the cross-machine direction and / or in the machine direction.

[0013] Therefore, the fiber furnish or the wet fiber web can also be attached outside the texture surface area, that is, for example, so that a coated fiber web having an uncoated end region is formed. In other words, the attachment area of the fiber furnish or the wet fiber web may be wider / larger than the texture surface area.

[0014] In one embodiment, the "texture surface area" includes a repeating pattern of concave regions and at least one non-concave region disposed between the concave regions, each concave region being recessed by a depth d from an adjacent non-concave region, the depth d being determined in a direction perpendicular to the surface of the texture substrate, and the depth d can be from 1 to 100 μm.

[0015] The texture substrate can be made of metal, plastic, or a suitable combination of materials. That is, the texture substrate can be a texture belt such as a metal belt, a polymer belt, a ceramic belt, or a composite material belt. The texture substrate such as a texture belt can have a length of 1 to 300 m and a width of 0.2 to 10 m. The texture surface area of the texture substrate can also be coated, for example, with a ceramic or plastic coating, for example, to adjust the surface energy. Usually, the texture surface area has a cell volume of 0.5 to 1,000 cm 3 / m 2 , preferably 1 to 500 cm 3 / m 2 , more preferably 1 to 100 cm 3 / m 2 and the texture surface area of the texture substrate is provided with a plurality of recesses so as to have.

[0016] By etching non-conductive or conductive grooves or cells, a pattern of recesses can be brought about in the texture surface area. It is also possible to deposit materials to generate convex regions. One example is the use of laser technology to engrave a texture belt or a texture cylinder.

[0017] By using the texture surface area in the described manner, it is possible to bring about a thin and uniform coating on the fiber web.

[0018] A coating agent is applied to the texture surface area of the texture substrate. The coating agent typically contains one or more coating components selected from wax, oil, polar lipids, metal soaps, rosin, or mixtures thereof. In one preferred embodiment, the coating component is an alkyl ketene dimer (AKD) or a fatty acid resin.

[0019] Examples of waxes include, for example, microcrystalline waxes such as paraffin wax, or polyethylene, polypropylene (PP), other natural or synthetic waxes, and wax emulsions thereof. The wax can be of any of fossil-based, natural-based, or bio-based such as beeswax, carnauba wax, or bio-wax (TopScreen (trademark), manufactured by Solenis).

[0020] An example of the oil is vegetable oil. Examples of polar lipids are fatty acids such as stearic acid, lauric acid, oleic acid, or triglycerides.

[0021] Examples of rosins include, for example, emulsions, emulsion sizing agents (i.e., those obtained by dissolving, dispersing, diluting, etc., rosin acid with an emulsifier or stabilizer such as casein or other cationic polyelectrolytes to make a liquid), or sizing agents of rosin soaps.

[0022] The coating component can be non-reactive or reactive. Examples of reactive coating components include one or more alkyl ketene dimers (AKD) or alkenyl succinic anhydrides (ASA).

[0023] The coating agent can be a water-in-oil (W / O) emulsion or an oil-in-water (O / W) emulsion, but an O / W emulsion is preferred. The coating agent is usually in the form of an O / W emulsion containing one or more of the above coating components. Particularly preferred O / W emulsions include O / W emulsions of styrene acrylate, styrene butadiene, polyvinyl acetate, or mixtures thereof. The aqueous emulsion usually contains additional additives such as an emulsifier, a stabilizer, and a biocide or preservative. The preferred average particle size of the emulsion is 10 to 5,000 nm, preferably 50 to 500 nm.

[0024] In certain embodiments, the coating agent is a micro or nano emulsion containing, for example, fatty acid triesters and / or hydrolyzed AKD. The coating agent preferably contains one or more adhesives such as cationic polymers.

[0025] By using the coating agent in this way, adhesion to the textured surface area can be controlled (control of dimensional stability, shrinkage) with just a thin coating.

[0026] The coating agent is preferably applied to the textured surface area in an amount of 0.1 - 100 gsm, preferably 0.3 - 50 gsm, more preferably 0.5 - 20 gsm. The coating agent is applied to the textured surface area and can then be heated to a temperature of 40°C - 400°C, preferably 60 - 240°C, most preferably 80 - 180°C, depending on the coating agent and grade used. The melting point of the coating component is preferably in the range of -40°C to +160°C, preferably +30°C to +160°C.

[0027] In one aspect, the fiber web contains a coating agent of 0.01 - 100 gsm, more preferably 0.1 - 50 gsm, when coated and dried.

[0028] In one embodiment, the coating agent is applied to the textured surface area before the fiber furnish. Preferably, the coating method for applying the coating agent is spray coating, curtain coating, roll coating apparatus, printing, dipping, etc. Preferably, the coating includes at least one coating step and one leveling step. The leveling step means removing excess coating liquid, for example, with a doctor blade or rod.

[0029] Preferably, before applying the coating agent, the textured surface area can be cleaned, for example, with a spray system or steam, to ensure it is clean.

[0030] In the casting process, fiber furnish can be applied to the coated texture surface area of the texture substrate. Next, the fiber furnish is dehydrated to provide a wet fiber web. The fiber furnish can be cast onto the coated texture surface area of the texture substrate. In this case, casting means that the fiber furnish is deposited (indirectly or directly) onto the texture surface area, preferably by using a non-contact deposition method. Examples of casting include various methods for applying a wet furnish to the surface area, such as curtain or slot die type feeding, spraying, rolling or rod.

[0031] Dehydration is preferably a process carried out through both mechanical dehydration, such as mechanical pressing or filtration, and evaporation. Of course, mechanical dehydration is preferred because it is more cost-effective than evaporation in removing water. Also, mechanical dehydration improves contact with the texture surface area, ensuring that the texture of the surface area can be imprinted on the film or web. Another advantage of mechanical dehydration is that the web is densified by the applied pressure (negative or positive), enhancing the final barrier properties. Most of the water is removed mechanically, but dehydration can also be carried out at a high temperature. Vacuum or capillary-based dehydration can also be used separately or simultaneously with mechanical dehydration. The dehydration process can also be accelerated by applying sonic or ultrasonic methods. Since there are limits to mechanical dehydration, the remaining water is preferably removed by evaporation. In this case, the substrate is heated by irradiation or convection, or by applying hot air or steam.

[0032] The preferred dry content of the fiber furnish when applied to the texture surface area is preferably 0.1 to 50% by weight, more preferably 0.5 to 30% by weight, and most preferably 1 to 25% by weight. In one embodiment, the dry content of the fiber furnish when applied to the texture surface area is 0.1 to 30% by weight, 1 to 20% by weight, 1 to 15% by weight, or 1 to 10% by weight.

[0033] Instead of applying a fiber furnish to the textured surface area, a wet fiber web can also be adhered to the coated textured surface area of the textured substrate. In this alternative, the wet fiber web is already formed when it is adhered to the textured surface area. This alternative increases the degree of freedom of the web forming procedure.

[0034] The dry content of the wet fiber web when adhered to the textured surface area is preferably 5 to 90% by weight, more preferably 8 to 80% by weight, and most preferably 10 to 60% by weight. The wet or moist web preferably has a given wet strength so that it can be transferred from the forming unit to the press and drying sections.

[0035] In one embodiment, the fiber furnish is an aqueous suspension of cellulose fibers, usually nanocellulose fibers. Thus, in one embodiment, the fiber web comprises cellulose fibers, preferably nanocellulose fibers.

[0036] The present invention provides a web that may contain cellulose fibers, preferably a web that may contain nanocellulose (i.e., a nanocellulose web). Nanocellulose, in the context of the present technology, shall mean nanoscale cellulose fibers or fibrils having at least one dimension, preferably a diameter of less than 1,000 nm. The nanocellulose suspension may also contain partially fibrillated, or non-fibrillated cellulose or lignocellulose fibers. The cellulose fibers preferably have a final specific surface area of the formed nanocellulose of about 1 to about 300 m 2 / g, for example 10 to 200 m 2 / g, more preferably 50 to 200 m 2It is fibrillated to a certain extent at / g. The average fibril diameter of the nanocellulose is 1 to 1,000 nm, preferably 10 to 1,000 nm. The nanocellulose can be characterized by analyzing high-resolution SEM or ESEM images.

[0037] The fiber web can contain nanocellulose in an amount of 0.01 to 100% by weight, based on the total solids content of the web. Preferably, the nanocellulose content in the web is at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, based on the total solids content of the web without coating. In one embodiment, the nanocellulose web contains, based on the total solids content, up to 50% by weight, such as up to 30% by weight, preferably up to 20% by weight, of cellulose or lignocellulose fibers that are partially fibrillated, or not fibrillated, with an average fibril diameter exceeding 1,000 nm.

[0038] There are various methods for producing nanocellulose, such as single-pass or multiple-pass refining, pre-hydrolysis followed by refining, or high-shear defibrillation or separation of fibrils. To make the production of nanocellulose energy-efficient and sustainable, usually one or more pretreatment steps are required. Thus, the cellulose fibers of the supplied pulp can be pretreated enzymatically or chemically, for example, to reduce the amount of hemicellulose or lignin. The cellulose fibers can be chemically modified before fibrillation, where the cellulose molecules contain functional groups other than (or in addition to) those found in the original cellulose. Such groups include, among others, carboxymethyl, aldehyde and / or carboxyl groups (cellulose obtained by N-oxyl catalytic oxidation, e.g., by "TEMPO"), or quaternary ammonium (cationized cellulose). After being modified or oxidized by one of the above methods, it is easier to defibrillate the fibers into nanocellulose.

[0039] Nanocellulose may contain some hemicellulose, and the amount depends on the plant source. Mechanical fibrillation of pretreated fibers, such as hydrolyzed, pre-swollen, or oxidized cellulose raw materials, is carried out using suitable devices such as refiners, grinders, homogenizers, colloid mills, friction grinders, ultrasonic processors, single-screw or twin-screw extruders, microfluidizers, macrofluidizers, or fluidizer-type homogenizers. Depending on the method of manufacturing nanocellulose, the product may also contain fine powder or nanocrystalline cellulose, or other chemical substances present, for example, in wood fibers or in the papermaking process. The product may also contain various amounts of micron-sized fiber particles that have not been efficiently fibrillated.

[0040] Nanocellulose can be produced from any wood cellulose fiber, whether hardwood or softwood fiber. Nanocellulose can also be made from microbial raw materials, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber raw materials. Nanocellulose is preferably made from pulp derived from unused fibers, such as pulp containing mechanical, chemical, and / or thermomechanical pulp. Nanocellulose can also be made from waste paper or recycled paper, i.e., pre-consumer and post-consumer waste.

[0041] Nanocellulose may be natural (i.e., chemically unmodified) or chemically modified. Phosphorylated nanocellulose is usually obtained by reacting cellulose fibers immersed in a solution of NH4H2PO4, water, and urea, followed by fibrillating the fibers. One particular method involves preparing an aqueous suspension of cellulose pulp fibers, phosphorylating the cellulose pulp fibers in the aqueous suspension with a phosphorylating agent, and then fibrillating in a manner common in the art. Suitable phosphorylating agents include phosphoric acid, phosphorus pentoxide, phosphorus oxychloride, diammonium hydrogen phosphate, and sodium dihydrogen phosphate.

[0042] The web, and the resulting fiber furnish, may also contain other cellulose components.

[0043] One advantage of the nanocellulose web is that it can transmit visible light. Therefore, preferably, the nanocellulose web has a transmittance of more than 70%, preferably more than 75%, more preferably more than 80% when measured for a web with a basis weight of about 30 gsm according to the standard specification DIN53147. It should be noted that the nanocellulose web can have a high transmittance for visible light and a low transmittance for UV light. However, the transmittance may be affected by the coating.

[0044] The web / fiber furnish may also contain one or more fillers such as nanofillers in the range of 1 to 30% by weight based on the total solids content of the web without coating. Typical nanofillers can be nanoclay, bentonite, silica or silicate, calcium carbonate, talcum, etc. 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. For example, when determining the particle size distribution of the filler using light scattering technology, the preferred particle size should be such that more than 90% is less than 2 μm.

[0045] The web / fiber furnish may also contain reinforcing agents such as cellulose derivatives, or natural starch, or modified starches such as cationic starch, nonionic starch, anionic starch or amphoteric starch. The reinforcing agent may also be a synthetic polymer. In a further embodiment, the nano-cellulose web / fiber furnish may also contain chemicals for retention and dewatering such as cationic polyacrylamide, anionic polyacrylamide, silica, nanoclay, alum, PDADMAC, PEI, PVAm, etc. In yet another embodiment, the web / fiber furnish may also contain other typical process chemicals or functional chemicals such as dyes or optical brighteners, defoamers, wet strength resins, biocides, hydrophobic agents, barrier chemicals, plasticizers, humectants, etc. The viscosity of the suspension, when measured at 40 °C and 100 rpm using a Brookfield viscometer, is preferably higher than 20 cP, more preferably higher than 40 cP, and most preferably higher than 60 cP. The higher viscosity (at a higher temperature) reduces or prevents the mixing of the wet web (furnish) with the surface coating layer.

[0046] The pH of the fiber furnish is not limited, but is preferably from 4 to 10, more preferably from 5 to 9. Casting of the fiber furnish in the coated surface area of the texture substrate is preferably carried out at a temperature of from 10 to 90 °C, more preferably from 20 to 70 °C.

[0047] The web / fiber furnish may contain cationic or anionic nanocellulose such as carboxymethylated nanocellulose. In one embodiment, the cationic or anionic nanocellulose is present in an amount of less than 50% by weight of the total amount of nanocellulose, preferably less than 40% by weight, more preferably less than 30% by weight.

[0048] The fiber web has a basis weight of 1 to 80 gsm, preferably 10 to 50 gsm, for example 10 to 40 gsm when dry. For certain applications, the basis weight can be small, for example, 0.1 to 20 gsm, more preferably even 0.1 to 10 gsm.

[0049] Then, the wet fiber web (according to any of the aforementioned options) is dried such that at least a portion of the coating agent migrates to the fiber web. This is schematically shown in Figure 1. The drying process can be carried out at a temperature higher than 60 °C, preferably higher than 80 °C, more preferably higher than 90 °C, and at a temperature less than 400 °C. The drying process is preferably carried out at a temperature higher than the melting point of at least one of the coating components, for example, higher than the melting point of wax, rosin, alkyl ketene dimer or fatty acid resin. The preferred temperature range is a temperature range such that the coating component migrates to the fiber web.

[0050] Depending on the process parameters, the fiber web may obtain some texture from the texture surface area. Thus, in one aspect of the method of the present invention, the coated fiber web is a coated textured fiber web. Process parameters that affect whether a texture is imparted from the texture surface area to the fiber web (physical texture effect) can be, for example, the contact time between the texture surface area and the fiber web, the drying temperature, the use of mechanical dewatering, the amount of coating agent and the type of coating agent. For example, when the recesses of the texture of the texture surface area are completely covered / filled with the coating agent, the physical texture effect may not be very obvious. However, when the recesses of the texture of the texture surface area are not completely covered / filled (e.g., 50% covered / filled) by the coating agent or a very low viscosity chemical substance, both chemical and physical texture effects may be obtained.

[0051] Accordingly, depending on the process parameters, the fibrous web may not obtain or may essentially not obtain a texture from the textured surface area, but the texture of the textured surface area is utilized only or mainly to enable the provision of an improved coating on the fibrous web, such as a thin and uniform coating. Accordingly, in another aspect of the method of the present invention, the coated fibrous web is a coated fibrous web without a texture obtained from the textured surface area (i.e., without a texture obtained by a physical texture effect), provided that the coating may result in a uniform or non-flat chemical effect.

[0052] The fiber furnish or the wet fibrous web is preferably in contact with the textured surface area at a length of at least 2 m, preferably at least 5 m, in the machine direction to ensure proper contact and movement of the coating agent. Such contact is effected with the aid of external pressure so that the web can be simultaneously dried using at least one press or dewatering fiber.

[0053] Using this method, the contact time between the coating agent and the fibrous web is increased. Preferably, the nip length is greater than 0.2 m, preferably greater than 0.5 m, and most preferably greater than 1.0 m. This results in a so-called "extended nip" or contact time between the coating agent and the fibrous web. In all conventional impact coatings, the length / time of the impact by the coating is very short.

[0054] Finally, remove the coated fiber web from the textured surface area, thereby providing the coated fiber web. The amount of coating agent transferred to the web depends on the coating agent, drying method, etc. For example, the amount of coating agent transferred to the web can be 20 to 100%, 20 to 99%, 20 to 90%, 20 to 80%, or 30 to 70% of the coating agent applied to the textured surface area. Therefore, the amount of coating agent transferred to the web can be, for example, 100%, 99%, 90%, 80%, or 70% of the coating agent applied to the textured surface area.

[0055] The fiber web typically has a width in the transverse direction of the textured substrate that is greater than 500 mm, preferably greater than 1,000 mm, more preferably greater than 1,500 mm. The coated fiber web is preferably transparent or translucent.

[0056] The resulting coated fiber web should have at least one barrier property selected from a UV barrier, an oil and grease barrier, an oxygen barrier, an aroma barrier, and a water vapor barrier, or a combination thereof. The fiber web can be a film. That is, the resulting product can be a cellulose film such as a nanocellulose film.

[0057] This technology can be applied to the production of nanocellulose webs or, preferably, to the extended nip (belt) dewatering or calendering of webs containing nanocellulose. This technology can also be used for other cellulose-based webs.

[0058] Excess coating agent can be removed from the textured surface area before step c or step d of the method of the present invention, for example, using a rod or a doctor blade.

[0059] Although the present invention has been described in connection with many embodiments, these should not be considered as limiting the present invention. Those skilled in the art can provide other embodiments included in the claims by combining various aspects and embodiments as necessary.

Claims

1. A method for coating a fibrous web, comprising: a. providing a textured substrate having at least one textured surface area; b. applying a coating agent to the textured surface area of the textured substrate to provide a coated textured surface area of the textured substrate; c. applying a fiber furnish to the coated textured surface area of the textured substrate, dewatering the fiber furnish to provide a wet fibrous web, or d. attaching a wet fibrous web to the coated textured surface area of the textured substrate; e. drying the wet fibrous web obtained in step c or step d such that at least a part of the coating agent migrates to the fibrous web; and f. removing the coated fibrous web from the textured surface area, thereby providing a coated fibrous web. The method, wherein the fibrous web is paper, paperboard or film, and the fibrous web contains cellulose fibers.

2. The method according to claim 1, wherein the textured surface area has a predetermined texture.

3. The method according to claim 1 or 2, wherein the fibrous web contains nanocellulose fibers.

4. The method according to any one of claims 1 to 3, wherein the textured substrate is a textured belt such as a metal belt, a polymer belt, a ceramic belt, or a composite material belt.

5. The method according to any one of claims 1 to 4, wherein the fiber furnish or the wet fibrous web is in contact with the coated textured surface area of the textured substrate at a length of at least 2 m in the machine direction.

6. The method according to any one of claims 1 to 5, wherein the coating agent comprises one or more coating components selected from wax, oil, polar lipid, metallic soap, rosin, or a mixture thereof.

7. The method according to any one of claims 1 to 6, wherein the coating agent comprises one or more coating components that are alkyl ketene dimer (AKD) or fatty acid resin.

8. The method according to any one of claims 1 to 7, wherein the coating agent is a water-in-oil (W / O) emulsion or an oil-in-water (O / W) emulsion.

9. The method according to any one of claims 1 to 8, wherein the coating agent comprises one or more adhesives.

10. The method according to any one of claims 1 to 9, wherein the fiber web comprises nanocellulose in an amount of 0.01 to 100% by weight based on the total solids content.

11. The method according to any one of claims 1 to 10, wherein the textured surface area has a cell volume of 0.5 to 1,000 cm ３ 2 and is provided with a plurality of recesses.

12. The method according to any one of claims 1 to 11, wherein the drying step is performed at a temperature higher than the melting point of at least one of the coating components of the coating agent.

13. The method according to any one of claims 1 to 12, wherein the drying step is performed at a temperature higher than 60°C and lower than 400°C.

14. The method according to any one of claims 1 to 13, wherein the coated fiber web is transparent or translucent.

15. The method according to any one of claims 1 to 14, wherein the coated fiber web is a coated textured fiber web.

16. The method according to any one of claims 1 to 15, wherein the coating composition is applied to the textured surface area in an amount of 0.1 to 100 gsm by dry weight.

17. The method according to any one of claims 1 to 16, wherein the coated fiber web has at least one barrier property selected from a UV barrier, an oil and grease barrier, an oxygen barrier, an aroma barrier and a water vapor barrier, or a combination thereof.

18. The method according to any one of claims 1 to 17, wherein the fiber web has a width in the transverse direction of the textured substrate of more than 500 mm.

19. The method according to any one of claims 1 to 18, wherein excess coating agent is removed from the textured surface area before step c or step d.

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