Temporary coating using nanocellulose and process for protecting a subtrate's surface

Abstract

A first aspect of the invention relates to a coated substrate, the substrate comprising or consisting of glass and / or metal, said substrate having a primary coating on at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate, on top of the primary coating. In a second aspect, the invention is directed to the use of nanocellulose as, preferably removable, protective coating on a surface of a substrate having a primary coating on at least one surface. A third aspect of the invention relates to a process for protecting a substrate, a fourth aspect is directed to an aqueous mixture comprising nanocellulose, preferably obtainable or obtained by the process of the second aspect of the invention, and a fifth aspect of the invention relates to an aqueous mixture comprising nanocellulose, further comprising (or being essentially free of) at least one binder or a reaction product of at least one binder and / or at least one filler.

Description

[0001] 240826W001

[0002] Temporary coating using nanocellulose and process for protecting a substrate’s surface

[0003] A first aspect of the invention relates to a coated substrate, comprising a substrate comprising or consisting of glass and / or metal, said substrate having a primary coating on at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate on top of the primary coating.

[0004] In a second aspect, the invention is directed to the use of nanocellulose as, preferably removable, protective coating on a surface of a substrate comprising or consisting of glass and / or metal, said substrate having a primary coating on at least one surface. A third aspect of the invention relates to a process for protecting a substrate's surface, a fourth aspect is directed to an aqueous mixture comprising nanocellulose, preferably obtainable or obtained by the process of the second aspect of the invention, and a fifth aspect of the invention relates to an aqueous mixture comprising nanocellulose, further comprising (or being essentially free of) at least one binder or a reaction product of at least one binder and / or at least one filler.

[0005] Nanocellulose, which is kind of a new generation of nanomaterials, has been receiving extensive attention from scientists and industry because of its specific chemical and physical properties. Nanocellulose (NC) is obtained or obtainable from cellulose fibers. NC comprises various forms such as microfibrilated cellulose (MFC), nanofibrillated cellulose (NFC), nanocrystalline cellulose (NCC) or nanocellulose that is made by bacteria. Generally, nanocellulose is understood as at least partially degraded and / or at least partially defibrillated cellulose. Process for preparing nanocellulose, either mechanically or chemically or mechanochemically are known, as well applications of nanocellulose, for example, for preparing paper or paperboard products, textile products, for preparing three dimensional sheet materials, or for preparing molded articles.

[0006] Several application areas exit, where a temporary surface coating is required to protect components and their surfaces during the transportation, storage and installation phases. This is the case, for example, for aluminum sheets in the aviation industry or for high-quality, functionalized glass. Until now, in the case of glass, additional thin protective glass layers have been applied, which, when the protection is no longer necessary or desired, then have to be removed and disposed. In the case of sheet metal for the aviation industry, coatings made of acrylic resin or of polyurethane have been tested. However, these coatings on the one hand do not meet the requirements for resistance or ease of removal and are on the other hand expensive. Furthermore, these materials are detrimental with a view towards recycling and sustainability.

[0007] Therefore, there was a need to provide a new temporary coating, which is easily removable after use and which overcomes the above discussed disadvantages in view of sustainability and which is more economical compared to existing coatings.

[0008] The invention thus relates in a first aspect to a coated substrate, comprising 240826W001

[0009] - 2 - a substrate, said substrate having at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate.

[0010] Preferably, the coated substrate comprises a substrate made of glass and / or metal, said substrate having a primary coating on at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate, on top of the primary coating.

[0011] Preferably, the primary coating comprises or is a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti-reflective coating, self-cleaning coating, and mixtures of two or more of these coatings. Preferably, the primary coating comprises or is a low emissivity coating (Low- E coating) and / or a silver (Ag) comprising coating, more preferably the primary coating comprises or is a low emissivity coating.

[0012] A low emissivity coating (low-E coating) has the purpose to reduce heat loss and improve energy efficiency. It may be a hard coating (robust) or a soft coating (more efficient). Low-E coatings consist of microscopically thin layers of metallic materials and / or ceramic materials that specifically reflect heat and allow light to pass through, wherein the metallic and / or ceramic materials are preferably selected from the group consisting of silver (Ag), metal oxide, preferably selected from the group consisting of titanium dioxide (TIO2), zinc oxide (ZnO), tin oxide (SnO2) and mixtures of two or more thereof, silicon nitride, and mixtures of two or more thereof. A protective coating preferably comprises a dielectric layer (e.g., ceramic materials). A reflective coating has the purpose to reduce solar radiation and heat gain. It preferably comprises a metallic and / or a non-metallic material, preferably selected from the group consisting of silver, aluminum, titanium doxide and mixtures of two or more thereof. A sun protection coating preferably comprises one or more, preferably more, layer(s) of silver. Its purpose os for high selectivity and optical quality. An anti-reflec- tive coating has the purpose to minimize glare and reflection, e.g., for showcases or displays. It preferably comprises a material selected from the group consisting of magnesium fluoride (MgF2), silicon dioxide (SI02), titanium oxide (TIO2), silicon nitride (Si3N4), aluminum oxide (Ai203), and mixtures of two or more thereof. A self-cleaning coating may be hydrophilic or hydrophobic and has the purpose to break down dirt under UV light and make cleaning easier. A self-cleaning coating is preferably selected from the group consisting of photocatalytic coating (hydrophilic), which preferably comprises titanium dioxide (TIO2), hydrophobic coating (lotus effect), which preferably comprises a nanostructured silicon compound and / or a polysiloxane (e.g., PDMS), hybrid coating, and mixtures of two or more thereof. A photocatalytic coating functions in that under UV light, reactive oxygen radicals are formed which break down organic contaminants. At the same time, the surface becomes superhydrophilic, so that water runs off as a film and takes dirt with it. The effect is preferably permanent, as TIO2is not consumed as a catalyst. A hydrophobic coating (lotus effect) functions in that micro- and nanostructures create extremely water-repellent surfaces, causing droplets to roll off and take dirt particles with them. A hybrid coating preferably comprises a combination of hydrophilic 240826W001

[0013] - 3 -

[0014] TiO2layers and organic additives (e.g., silanes, maleic anhydride) to improve adhesion and photocatalytic performance.

[0015] A nanocellulose based coating has the advantage that it is made from renewable sources, i.e. cotton and / or wood and can be made from waste materials such as used textiles. Furthermore, it offers the advantage that it can be used and applied in mostly aqueous, preferably fully aqueous media, thus allowing to avoid the use of organic solvents and making the coating eco-friendly. Furthermore, as outlined in more detail below, the nanocellulose based coatings have superior properties in view of hardness, elasticity and are very resistant towards scratching. In addition, these nanocellulose based coatings offer the great advantage that the nanocellulose, even if applied onto a substrate from a mixture, suspension and dried thereon, is still hydrophilic, this allowing an easy removal after the coating has fulfilled its purpose - simply by washing it off with an aqueous medium such as water.

[0016] Preferably, the coated substrate is a temporarily coated substrate comprising a substrate, said substrate having at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate. "Temporarily coated” means that the coating is present on at least a part of said at least one surface of the substrate as long as needed to fulfill its purpose, i.e. as long as protection is required, for example, during a transportation, storage and / or installation phase.

[0017] As indicated above, the coated substrate comprises a substrate, said substrate having at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate. Preferably, the substrate comprises or is made of, optionally coated, glass and / or metal. A glass substrate is preferably float glass, which is optionally coated with a metal oxide layer, at least on a part of its surface. Metal oxide(s) for such metal oxide layers are for example, NiCrOx (antireflective), ZnO and / or SnC>2 (chemical protection, adhesion improvement). The at least one layer of nanocellulose is then present on top of the metal oxide layer, i.e. on the surface of the metal oxide layer facing away from the at least one surface of the substrate on which the metal oxide layer is present. Regarding a metal substrate, the metal comprises one or more metallic materials selected from the group consisting of metal and metal alloy. A metal substrate is preferably a sheet metal.

[0018] It is preferred that the layer of nanocellulose has a thickness in the range of from 1 to 1000 pm, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 10 to 50 pm, more preferably in the range of from 10 to 40 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer. In some embodiments, especially when protective coatings are intended, it is preferred that the layer of nanocellulose has a thickness in the range of from 1 to 1000 pm, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer. 240826W001

[0019] - 4 -

[0020] Preferably, the layer of nanocellulose has a hardness of > 50 MPa, more preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0021] It is preferred that the layer of nanocellulose has an Young's modulus of > 5000 MPa, more preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0022] The layer of nanocellulose when present on at least a part of said at least one surface of the substrate is preferably dry, i.e. it comprises less than 20 weight-%, more preferably less than 15 weight-%, more preferably less than 10 weight-% of water, based on the total weight of the layer of nanocellulose being 100 weight-%.

[0023] The nanocellulose is preferably obtained or obtainable from cellulose fibers. Processes for preparing nanocellulose are known and a skilled person generally knows what nanocellulose is and how it is prepared.

[0024] In some preferred embodiments of the inventive coated substrate, the nanocellulose is obtained or obtainable from cellulose fibers, preferably from a polymeric material comprising cellulose fibers, preferably by a process for preparing nanocellulose from a polymeric material comprising cellulose fibers, the process comprising:

[0025] (i) Providing pieces p1 of the polymeric material comprising cellulose fibers;

[0026] (ii) Shredding the pieces p1 provided according to (i) in n shredding devices SD(i) wherein n is an integer with n>1 and 1=1 ...n, thereby obtaining pieces p2, which comprise cellulose fibers;

[0027] (iii) Preparing an aqueous mixture comprising the pieces p2 at a temperature T 1 and adjusting the temperature of the aqueous mixture comprising the pieces p2 to a temperature T2 with T2 > T1, thereby obtaining an aqueous mixture comprising the pieces p2 and having temperature T2;

[0028] (iv) Introducing at least one enzyme capable of degrading cellulose (cellulase) into the aqueous mixture obtained according to (iii), thereby obtaining an aqueous mixture comprising the pieces p2 and at least one enzyme, wherein the aqueous mixture has temperature T2;

[0029] (v) Milling the aqueous mixture obtained according to (iv) in a milling device MD(1), thereby obtaining an aqueous mixture comprising the at least one enzyme and milled pieces p3, which comprise at least partially degraded cellulose fibers;

[0030] (vi) Milling the aqueous mixture obtained according to (v) in a stirred media mill SMM, thereby obtaining an aqueous mixture comprising the at least one enzyme and nanocellulose (at least partially degraded and / or at least partially defibrillated cellulose).

[0031] Said process for preparing nanocellulose is outlined in more detail below: 240826W001

[0032] - 5 -

[0033] A fiber is a three dimensional body with one spatial extension being substantially larger (the length “L”) than at least one other spatial extension (width "w”). A cellulose fiber comprises beta-1 , 4-glycosidically connected glucose residues as so called cellulose polymer chains, wherein a plurality of these cellulose polymer chains forms a so called microfibril. A microfibril comprises crystalline and amorphous region(s). In turn, a plurality of microfibrils are arranged to form a so called macrofibril. Further, a plurality of macrofibrils forms the cellulose fiber, which has a diameter d in the range of from 20 to 60 m.

[0034] Applying the at least one enzyme capable of degrading cellulose first in step (iv), i.e. after shredding the pieces p1 to the pieces p2 and preparation of aqueous mixture from the pieces p2 allows to achieve much faster degradation rates. Compared to other processes, the inventive process offers the advantage that addition of harsh chemicals such as sulfuric acid (H2SO4) and / or sodium hydroxide (NaOH) can be avoided: No H2SO4 is required to remove amorphous parts of the cellulose and no NaOH is required in order to swell cellulose in order to make it easier to be milled. This gives the further advantage that the final nanocellulose obtained from the inventive process does not have to be cleaned from these chemicals after the defibrillation process is finished.

[0035] According to step (I), pieces p1 of a polymeric material comprising cellulose fibers are provided. Preferably, the polymeric material comprising cellulose fibers is a textile or a cellulose pulp, more preferably a cellulose pulp, more preferably a dissolving-grade pulp. A cellulose pulp is based on at least one component selected from the group consisting of plant (especially wood and / or fiber crops), waste paper, rags and mixtures of two or more thereof. Dissolving-grade pulp is a highly pure cellulose pulp with a high o-cellulose content (> 90 weight- %) and low levels of hemicellulose (< 4 weight- %). Preferably, softwood bleached pulp is used.

[0036] Step (ii)

[0037] Shredding the pieces p1 provided according to (I) is done according to step (II) in n shredding devices SD(i). Preferably, the n shredding devices SD(i) comprise at least a first shredding device SD(1) and a second shredding device SD(2), wherein step (II) preferably comprises:

[0038] (11.1) Shredding the pieces p1 , which have a bulk density bdpiand a length lpi, provided according to (I) in the first shredding device SD(1), thereby obtaining pieces p1-1 , which comprise cellulose fibers, wherein the pieces p1 -1 have a length with lpi-i < lp-i ;

[0039] (11.2) Shredding the pieces p1 -1 obtained according to (ii-1) in the second shredding device SD(2), thereby obtaining pieces p2, which comprise cellulose fibers, wherein the pieces p2 have a bulk density bdP2 with bdP2 < bdpi.

[0040] The length of the pieces p1 and pieces p1 -1 is preferably the respective Ferret diameter of these pieces. The bulk density is preferably determined according to DIN EN ISO 60 (2023-12). As will be understood, step (II) 240826W001

[0041] - 6 - and also steps (ii.1 ) and (ii.2) are both carried out in "dry mode”, i.e. the respective shredding is done without addition of water or another solvent and the pieces to be shredded are also provided in dry state (dry shredding stage(s)).

[0042] It is preferred that the n shredding devices SD(i), preferably the first shredding device SD(1) and the second shredding device SD(2), are selected from the group consisting of a shredder, a guillotine, a hammer mill, and a cutting mill, wherein SD(1) is preferably a shredder, the shredder being more preferably a double-shaft shredder or a four-shaft shredder and / or SD(2) is preferably a hammer mill.

[0043] Preferably, the particles p2 have a bulk density in the range of from 10 to 40 kg / m3, more preferably in the range of from 10 to 20 kg / m3. Bulk density is determined in that a vessel with a volume of 1 m3is completely filled with (dry) particles p2 and then weighted, wherein the bulk density is the resulting weight per volume.

[0044] Steps (Hi), (iv)

[0045] According to step (iii), an aqueous mixture comprising the pieces p2 at a temperature T1 is prepared and the temperature of the aqueous mixture comprising the pieces p2 is adjusted to a temperature T2 with T2 > T1 , thereby obtaining an aqueous mixture comprising the pieces p2 and having temperature T2; and according to step (iv), at least one enzyme capable of degrading cellulose (cellulase) is introduced into the aqueous mixture obtained according to (iii), thereby obtaining an aqueous mixture comprising the pieces p2 and at least one enzyme, wherein the aqueous mixture has temperature T2.

[0046] Preferably, the aqueous mixture comprising the pieces p2 according to (iii) and / or, preferably and, the aqueous mixture comprising the pieces p2 and at least one enzyme according to (iv) comprises said pieces p2 in a concentration in the range of from 1 to 10 weight-%, preferably in the range of from 1 to 7 weight-%, preferably in the range of from 3 to 7 weight-%, more preferably in the range of from 3 to 5 weight-%, each based on the total weight of the aqueous mixture being 100 weight-% (solid content in aqueous mixture).

[0047] It is preferred that the pH value of the aqueous mixture comprising the pieces p2 is adjusted in step (iii) to be in the range of from 3 to 6, preferably in the range of from 4 to 5, more preferably in the range of from 4.2 to 4.8, preferably by addition of an aqueous solution comprising at least one buffer; and / or wherein in step (iv) together with or prior to the introduction of the at least one enzyme, the pH value of the aqueous mixtures is adjusted to be in the range of from 3 to 6, preferably in the range of from 4 to 5, more preferably in the range of from 4.2 to 4.8, preferably by addition of an aqueous solution comprising at least one buffer.

[0048] Preferably, the at least one buffer is selected acetic acid / sodium acetate buffer and / or citrate buffer (citric acid monohydrate, potassium hydroxide and water), preferably citrate buffer. 240826W001

[0049] - 7 -

[0050] T 1 is preferably a temperature in the range of from 10 to 40°C and T2 is preferably a temperature suitable for the at least one enzyme for degrading cellulose (cellulase) with T2, with T2 > T1 . A "temperature suitable for the at least one enzyme for degrading cellulose (cellulase)” means a temperature at which the respective enzyme works at its optimum. These temperatures are known to the skilled person and can be taken for each enzyme from the manufacturers data. In some embodiments, especially when Spartec™ CEL 100 (from BASF) is used as enzyme, T1 is preferably a temperature in the range of from 10 to 40°C and T2 is preferably a temperature in the range of from 30 to 60°C, with T2 > T1 .

[0051] It is preferred that step (iii) comprises:

[0052] (iii.1) Preparing an aqueous mixture comprising the pieces p2 having a viscosity .(1) at a temperature T1 and adjusting the temperature of the aqueous mixture comprising the pieces p2 to a temperature T2 with T2 > T1;

[0053] (111.2) Optionally incubating the aqueous mixture comprising the pieces p2 at temperature T2 for a period of time of at least 1 minute;

[0054] (111.3) Milling the aqueous mixture of step (iii.1 ) or of step (iii.2) for a period of time in a milling device MD(0), so that the total energy input in kWh brought into the aqueous mixture per ton of aqueous mixture is in the range of from 10 to 100 kWh / t, preferably in the range of from 40 to 80 kWh / t; thereby obtaining an aqueous mixture comprising the pieces p2 and having a viscosity .(2), with .(2) < pi(1).

[0055] "Incubating” in optional step (iii.2) means that the mixture is kept without milling - said step can also be called "soaking”, i.e. the pieces p2 are allowed to soak up by the aqueous medium. Preferably, the viscosity .(2) of the aqueous mixture comprising the pieces p2 obtained in (iii.3) is in the range of from 0.033 x .(1) < .(2) < 0.25 x .(1). In some preferred embodiments, the viscosity .(2) is < 1000 mPas, more preferably the viscosity .(2) is in the range of from 100 to 500 mPas. Viscosity is, for example, measured with a HAAKETMViscotest- er™ 3 Rotational Viscometer. The milling device MD(0) is preferably a mill with rotor stator geometry or a stirred media mil, more preferably, MD(0) is a same milling device as MD(1) described herein in more detail below.

[0056] Step (iv)

[0057] According to step (iv), at least one enzyme capable of degrading cellulose (cellulase) is introduced into the aqueous mixture obtained according to (iii), thereby obtaining an aqueous mixture comprising the pieces p2 and at least one enzyme, wherein the aqueous mixture has temperature T2. Preferably, the enzyme capable of degrading cellulose introduced in step (iv) is a cellulase, preferably selected from the group consisting of beta-glucosidase, endo-1,4-beta-D-glucanase, exo-1,4-beta-D-glucanase and mixtures of two or more of these enzymes. More preferably the enzyme is selected from the group consisting of Ctec2 (Novoensis Corp), 240826W001

[0058] - 8 -

[0059] Ctec3 (from Novoensis Corp), Spartec™ CEL 100 (from BASF) and mixtures of two or more thereof. Preferably the enzyme, preferably the cellulase, has an activity in the range of from 1 to 100 FPU / g, more preferably in the range of from 4 to 10 FPU / g. The concentration refers to the solids content of cellulose in the suspension. In some preferred embodiments, the enzyme comprises or is at least Spartec™ CEL 100 (from BASF), wherein SpartecTM CEL 100 has a density in the range of from 1.05 to 1.1 g / mL and a pH in the range of from 4.2 to 4.5.

[0060] Preferably, the enzyme is introduced in step (iv) so that in the range of from 1 to 100 FPU / g, preferably in the range of from 4 to 10 FPU / g, are finally present, wherein “g” refers to gram of dry pieces p2.

[0061] Step (v)

[0062] According to step (v), the aqueous mixture obtained according to (iv) is milled in a milling device MD(1), thereby obtaining an aqueous mixture comprising the at least one enzyme and milled pieces p3, which comprise at least partially degraded cellulose fibers. The milling device MD(1) is preferably a mill with rotor stator geometry or a stirred media mil. More preferably, the milling device MD(1) is a mill with rotor stator geometry, preferably colloid mill or refiner, having a grinding gap with a, preferably adjustable, width in the range of from 100 to 700 m, preferably in the range of from 100 to 400 pm.

[0063] Preferably, the grinding gap width is changed during step (v), wherein the grinding gap width ggw(1) at the beginning of step (v) is preferably in the range of from 100 to 700 pm, more preferably in the range of from 100 to 400 pm, and the width of the grinding gap is preferably changed during step (v) to ggw(12), wherein ggw(2) is preferably in the range of from100 to 700 pm, more preferably in the range of from 100 to 400 pm, with ggw(2)< ggw(1). For example, the width of the grinding gap at the beginning of step (v) is adjusted to be 350 pm (ggw(0)) and is then reduced over step (v) to ggw(0), which is in the range of from 100 to 200 pm.

[0064] More preferably, the milling device MD(1) is a stirred media mill SMM(MD(1)), which preferably comprises a dynamic gap separation system with a dynamic gap opening in the range of from 0.5 to 2 mm, preferably in the range of from 0.8 to 1.5 mm, more preferably in the range of from 0.9 to 1.1 mm. Preferably, the stirred media mill SMM(MD(1)) comprises milling beads having a diameter in the range of from 1 to 7 mm, preferably in the range of from 3 to 5 mm. The milling beads preferably consist of a material selected from the group consisting of ceramic; metal, preferably stainless steel; thermoset, preferably a thermoset polyurethane; and mixtures of two or more of these materials, wherein the milling beads more preferably consist of zirkonoxide-ce- ramic milling beads stabilized with yttrium and / or with cerium.

[0065] Preferably, the stirred media mill SMM(MD(1)) comprises a stationary vessel and a rotor configured to rotate within the vessel, wherein the rotor comprises a plurality of, preferably at least 4, more preferably at least 10, more preferably at least 20, propelling means configured for, when rotating the rotor, propelling the milling 240826W001

[0066] - 9 - beads and the aqueous mixture to move within the vessel. Preferably, the dynamic gap separation system is arranged within the rotor, preferably the dynamic gap separation system is part of the rotor. Preferably, the propelling means are disks or finger-like structures extending radially outward from the rotor towards an inner surface of the vessel and having a diameter and / or maximum cross-sectional width in the range of from 5 to 30 mm, preferably in the range of from 10 to 25 mm. Preferably, the propelling means have a shape selected from the group consisting of a cylindrical shape, preferably the shape of a cylinder; a rectangular shape, preferably with its longer side extending outward from the rotor; a cone shape, preferably a truncated cone shape, more preferably with the cone's base being arranged closer to the rotor's surface than the cone's narrower end; a polyhedron shape, preferably a pyramid shape, more preferably a truncated polyhedron, more preferably with the polyhedron's polygonal base being arranged closer to the rotor's surface than it's narrower end. Preferably, the vessel on its inside, preferably on its side facing the rotor, comprises a plurality of, preferably at least 4, more preferably at least 10, more preferably at least 20, redirecting means configured for, when rotating the rotor within the vessel, redirecting the movement of the milling beads within the vessel. Preferably, the redirecting means are finger-like structures extending radially inward from the vessel and having a diameter and / or maximum cross-sectional width in the range of from 5 to 30 mm, preferably in the range of from 10 to 25 mm. Preferably, the redirecting means have a shape selected from the group consisting of a cylindrical shape, preferably the shape of a cylinder; a rectangular shape, preferably with its longer side extending inward from the vessel; a cone shape, preferably a truncated cone shape, more preferably with the cone's base being arranged closer to the vessel's surface than the cone's narrower end; a polyhedron shape, preferably a pyramid shape, more preferably a truncated polyhedron, more preferably with the polyhedron's polygonal base being arranged closer to the vessel's surface than it's narrower end. Preferably, the rotor rotates within the vessel at a circumferential speed cs1 in the range of from 5 to 50 m / s, preferably in the range of from 8 to 14 m / s. Preferably, the stirred media mill SMM(MD(1)) has an active milling chamber volume in the range of from 5 to 150 Liters, preferably in the range of from 5 to 100 Liters, more preferably of 60 Liters. The active milling chamber volume of the stirred media mill SMM(MD(1)) is the volume of the empty vessel without rotor and without milling beads. A MacroMedia wet mill from company Buhler is preferred as stirred media mill SMM(MD(1)).

[0067] Preferably, the milling device MD(1) or the stirred media mill SMM(MD(1) is horizontally aligned and the aqueous mixture is moved in MD(1) or SMM in horizontal direction.

[0068] According to step (v), an aqueous mixture is obtained, which comprises the at least one enzyme and milled pieces p3, which comprise at least partially degraded cellulose fibers.

[0069] Step (vi) 240826W001

[0070] - 10 -

[0071] According to step (vi), the aqueous mixture obtained according to (v) is milled in a stirred media mill SMM, thereby obtaining an aqueous mixture comprising the at least one enzyme and nanocellulose (at least partially degraded and / or at least partially defibrillated cellulose).

[0072] Preferably, the stirred media mill SMM comprises milling beads having a diameter in the range of from 100 m to 3 mm, preferably in the range of from 300 pm to 800 pm. The milling beads preferably consist of a material selected from the group consisting of ceramic; metal, preferably stainless steel; thermoset, preferably a thermoset polyurethane; wherein the milling beads more preferably consist of zirkonoxide-ceramic milling beads stabilized with yttrium and / or with cerium. Preferably, SMM comprises a stationary vessel and a rotor configured to rotate within the vessel, wherein the rotor comprises a plurality of, preferably at least 9, more preferably at least 18, more preferably at least 60, propelling means configured for, when rotating the rotor, propelling the milling beads and the aqueous mixture to move within the vessel. The propelling means are preferably disks or finger-like structures extending radially outward from the rotor towards an inner surface of the vessel. Preferably, the propelling means have a shape selected from the group consisting of a cylindrical shape, preferably the shape of a cylinder.

[0073] It is preferred that the vessel on its inside, preferably on its side facing the rotor, comprises a plurality of, preferably at least 9, more preferably at least 18, more preferably at least 60, redirecting means configured for, when rotating the rotor within the vessel, redirecting the movement of the milling beads within the vessel. The redirecting means are preferably finger-like structures extending radially inward from the vessel. The redirecting means preferably have a cylindrical shape, more preferably the shape of a cylinder.

[0074] Preferably, the vessel on its inner surface comprises a liner, wherein the liner comprises, preferably consists of, a material selected from the group consisting of ceramic; metal, preferably Silicone Carbide SIC, stainless steel; thermoset, preferably thermoset Polyurethane; ;and mixtures of two or more of these materials, wherein the material preferably at least comprises Silicone Carbide SIC. The rotor preferably rotates within the vessel at a circumferential speed cs1 in the range of from 5 to 50 m / s, preferably in the range of from 8 to 14 m / s. SMM has preferably an active milling chamber volume in the range of from 2 to 200 Liters, preferably in the range of from 60 to 150 Liters, more preferably of 60 Liters. The active milling chamber volume of SMM is the volume of the empty vessel without rotor and without milling beads. SMM is preferably a High performance stirred media mill (HPM) mill from any one of the companies Buhler, Bachofen or Netzsch, more preferably a Netzsch LMZ type mill with SIC liner.

[0075] Preferably, the stirred media mill SMM is horizontally aligned and the aqueous mixture is moved in SMM in horizontal direction.

[0076] It is preferred that at least in one step of (iv), (v) and (vi), more preferably in each step (iv), (v) and (vi), the temperature of the respective aqueous mixture is maintained at T2. 240826W001

[0077] - 11 -

[0078] It is also preferred that at least in one step of (iv), (v) and (vi), more preferably in each step (iv), (v) and (vi), the pH value is adjusted or maintained in the range of from 4.0 to 6.0, preferably in the range of from 4.5 to 5.5.

[0079] Solid / liquid separation

[0080] According to step (v) and / or step (vi), an aqueous mixture is obtained. It is preferred that the aqueous mixture obtained in (v) and / or, preferably and, the aqueous mixture obtained in (vi) comprises glucose (monomer).

[0081] The inventive process preferably further comprises separation of solid and liquid parts of the aqueous mixture obtained in (v) or in (vi), preferably by gravitational forces, more preferably by centrifugation, thereby obtaining a separated solid part comprising the at least partially degraded and / or at least partially defibri Hated cellulose, and a separated liquid part comprising dissolved glucose (monomer) and at least a part of the at least one enzyme; and optionally removing the separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme, from the solid part.

[0082] Preferably, the process further comprises after (v) and before (vi)

[0083] (x-1) Increasing the solid content of the aqueous mixture obtained in (v), which comprises the at least one enzyme and milled pieces p3, which comprise at least partially degraded cellulose fibers, preferably by at least 1 weight-%, based on the total weight of the aqueous mixture being 100 weight-%, wherein increasing the solid content is preferably done by centrifugation; thereby obtaining an aqueous mixture with an increased solid content, said aqueous mixture with an increased solid content comprising at least a part of the at least one enzyme and milled pieces p3, which comprise at least partially degraded cellulose fibers, wherein said aqueous mixture with an increased solid content is then subjected to the milling step according to (vi); and obtaining a separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme;

[0084] (x-2) Optionally removing the separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme.

[0085] Increasing the solid content allows to make the milling step (vi) more efficient. Preferably, increasing the solid content is also called "dewatering”, wherein the dewatering is preferably adjusted so that the solids concentration in the aqueous mixture used in the milling step (vi) is raised to in the range of from 8 to 12 weight%, based on the total weight of the aqueous mixture with an increased solid content and comprising at least a part of the at least one enzyme and milled pieces p3 being 100 weight-%.

[0086] Preferably, the process further comprises after (vi) 240826W001

[0087] - 12 -

[0088] (y-1) Increasing the solid content of the aqueous mixture obtained in (vi), which comprises the at least one enzyme and at least partially degraded and / or at least partially defibrillated cellulose, preferably by at least 1 weight-%, based on the total weight of the aqueous mixture being 100 weight-%, wherein increasing the solid content is preferably done by centrifugation; thereby obtaining an aqueous mixture with an increased solid content, said aqueous mixture with an increased solid content comprising the at least one enzyme and at least partially degraded and / or at least partially defibrillated cellulose, and a separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme;

[0089] (y-2) removing the separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme, thereby obtaining the aqueous mixture with an increased solid content in separated form

[0090] (y-3) mixing the aqueous mixture with an increased solid content obtained in (y-2) with water and optionally with a stabilization agent, thereby obtaining an aqueous mixture with a re-decreased solid content;

[0091] (y-4) repeating step (y-1) based on the aqueous mixture with a re-decreased solid content obtained in (y-3), thereby obtaining: an aqueous mixture with an increased solid content, said aqueous mixture with an increased solid content comprising which comprises the at least one enzyme and at least partially degraded and / or at least partially defibrillated cellulose, and a separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme;

[0092] (y-5) optionally removing the separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme.

[0093] Stabilizing agents are known to the skilled person and comprise, for example, sodium benzoate.

[0094] Recycling of liquid fraction(s)

[0095] It is preferred that the separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme rand / or, preferably and, the separated liquid part, which comprises dissolved glucose and at least a part of the at least one enzyme is / are recycled into step (iv). Recirculating at least a part of the separated liquid part t is advantageous as also a part of the enzyme is thus recycled to step (iv). The enzyme costs account for a considerable part of the overall processing costs. Therefore, an enzymatic recycling is advantageous at least in view of economic reasons.

[0096] Removable coating

[0097] Regarding the coated substrate according to the present invention, the layer of nanocellulose is preferably removable by addition of an aqueous medium, wherein the aqueous medium comprises at least 98 weight-%, more preferably at 240826W001

[0098] - 13 - least 99 weight-%, more preferably at least 99.5 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%. The inventive surface coating is especially useful for transport, storage and installation purposes, wherein elements comprising surfaces made of glass and / or metal shall be protected against, for example, scratching or soiling, pollution, contamination, indentation but wherein afterwards the surface coating has to be removed.

[0099] 2ndaspect - Use

[0100] A second aspect of the invention is directed to the use of nanocellulose as, preferably removable, protective coating on a surface.

[0101] All details, embodiments and preferred embodiments disclosed above in the section related to the first aspect of the invention, i.e. the coated substrate, apply also to the use of the second aspect of the invention.

[0102] Preferably, the nanocellulose is used as, preferably removable, protective coating on a surface, wherein the surface to be protected is preferably the surface of a substrate, which comprises or is made of, glass and / or metal, the substrate having a primary coating on at least one surface, wherein the primary coating preferably comprises or is a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti-reflective coating, self-cleaning coating, and mixtures of two or more of these coatings. Preferably, the primary coating comprises or is a low emissivity coating (Low-E coating) and / or a silver (Ag) comprising coating, more preferably the primary coating comprises or is a low emissivity coating.

[0103] A low emissivity coating (low-E coating) has the purpose to reduce heat loss and improve energy efficiency. It may be a hard coating (robust) or a soft coating (more efficient). Low-E coatings consist of microscopically thin layers of metallic materials and / or ceramic materials that specifically reflect heat and allow light to pass through, wherein the metallic and / or ceramic materials are preferably selected from the group consisting of silver (Ag), metal oxide, preferably selected from the group consisting of titanium dioxide (TiO2), zinc oxide (ZnO), tin oxide (SnO2) and mixtures of two or more thereof, silicon nitride, and mixtures of two or more thereof.

[0104] A protective coating preferably comprises a dielectric layer (e.g., ceramic materials). A reflective coating has the purpose to reduce solar radiation and heat gain. It preferably comprises a metallic and / or a non-metallic material, preferably selected from the group consisting of silver, aluminum, titanium doxide and mixtures of two or more thereof. A sun protection coating preferably comprises one or more, preferably more, layer(s) of silver. Its purpose os for high selectivity and optical quality. An anti-reflective coating has the purpose to minimize glare and reflection, e.g., for showcases or displays. It preferably comprises a material selected from the group consisting of magnesium fluoride (MgF2), silicon dioxide (Si02), titanium oxide (TiO2), silicon nitride (Si3N4), aluminum oxide (AI203), and mixtures of two or more thereof. A self-cleaning coating may be hydrophilic or hydrophobic and has the purpose to break down dirt under UV light and make cleaning easier. A self-cleaning coating is preferably selected from the group consisting 240826W001

[0105] - 14 - of photocatalytic coating (hydrophilic), which preferably comprises titanium dioxide (TIO2), hydrophobic coating (lotus effect), which preferably comprises a nanostructured silicon compound and / or a polysiloxane (e.g., PDMS), hybrid coating, and mixtures of two or more thereof. A photocatalytic coating functions in that under UV light, reactive oxygen radicals are formed which break down organic contaminants. At the same time, the surface becomes superhy- drophilic, so that water runs off as a film and takes dirt with it. The effect is preferably permanent, as Ti O2is not consumed as a catalyst. A hydrophobic coating (lotus effect) functions in that micro- and nanostructures create extremely water-repellent surfaces, causing droplets to roll off and take dirt particles with them. A hybrid coating preferably comprises a combination of hydrophilic TiO2layers and organic additives (e.g., silanes, maleic anhydride) to improve adhesion and photocatalytic performance.

[0106] Preferably, the nanocellulose is obtained or obtainable from cellulose fibers, preferably obtained or obtainable by a process as described above in the section related to the first aspect of the invention.

[0107] Preferably, the nanocellulose coating further comprises at least one binder, wherein the binder is preferably selected from the group consisting of binder based on a polycarboxylic acid, optionally bound to a latex particle, and a polyalcohol (Acrodur®); butanetetracarboxylic acid (BTCA); modified polyethylene wax (Aquamat® 272N); and mixtures of two or more thereof, wherein the at least one binder is present in the range of from 5 to 50 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%. In some embodiments, especially when protective coatings are intended, it is preferred that the nanocellulose coating comprises essentially no binder, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm, are binder based on the total weight of the nanocellulose coating being 100 weight-%.

[0108] It is preferred that the nanocellulose coating further comprises at last one filler, wherein the filler is preferably selected from the group consisting of clay, loam, talc, mica, rock flour, carbon black, silicate, carbonate, oxide and mixtures of two or more thereof; wherein the at least one filler is present in the range of from 5 to 50 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%. In some embodiments, especially when protective coatings are intended, it is preferred that the nanocellulose coating comprises essentially no filler, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm, are filler based on the total weight of the nanocellulose coating being 100 weight-%.

[0109] It is preferred that the nanocellulose coating further comprises at least one C16-C18 fatty alcohol polyethylene gly- col-ether, preferably present in up to 5 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%. Preferably, the at least one C16-C18 fatty alcohol polyethylene glycol-ether is based on a blend of C16- C18 fatty alcohols and ethylene oxide and preferably has an ethoxylation degree in the range of from 70 to 90%, more preferably in the range of from 75 to 85%. Preferably, the at least one C16-C18 fatty alcohol polyethylene glycol-ether has a molecular weight in the range of from 1440 to 1700 g / mol. 240826W001

[0110] - 15 -

[0111] It is preferred that the nanocellulose coating further comprises at least one non-ionic surfactant, preferably present in up to 1 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%. Preferably, the at least one non-ionic surfactant comprises or is a C16-C18 fatty alcohol polyethylene glycol-ether based on a blend of C16 to C18 fatty alcohols and unsaturated C18 fatty alcohols with ethylene oxide (> 2.5 EO).

[0112] Fatty alcohol polyethylene glycol-ether and / or non-ionic surfactant improve the washability in step (ill).

[0113] The nanocellulose coating when present on at least a part of said at least one surface of the substrate is preferably dry, i.e. it comprises less than 50 weight-%, more preferably < 10 weight-%, more preferably in the range of from 1 to 10 weight-% of water, based on the total weight of the nanocellulose coating being 100 weight-%.

[0114] Preferably, the nanocellulose coating is removable by addition of an aqueous medium, wherein the aqueous medium comprises at least 98 weight-%, more preferably at least 99 weight-% more preferably at least 99.5 weight-% more preferably 100 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

[0115] It is preferred that the surface to be protected is the surface of a substrate, which comprises or is made of, optionally coated, glass and / or metal. Preferably, the nanocellulose coating has a thickness in the range of from 1 to 1000 m, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 10 to 50 pm, more preferably in the range of from 10 to 40 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer. In some embodiments, especially when protective coatings are intended, it is preferred that the layer of nanocellulose has a thickness in the range of from 1 to 1000 pm, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer. Preferably, the nanocellulose coating has a hardness of > 50 MPa, more preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN. Preferably, the nanocellulose coating has an Young's modulus of > 5000 MPa, more preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0116] 3rdaspect - Process for protecting a substrate

[0117] A third aspect of the invention is directed to a process for preparing a protective coating on a substrate, the process comprising 240826W001

[0118] - 16 -

[0119] (i) applying a mixture comprising nanocellulose and a solvent to a surface of a substrate (to be protected); thereby obtaining a film comprising solvent and nanocellulose on at least a part of the surface of the substrate;

[0120] (ii) removing solvent from the film comprising nanocellulose obtained in step (i) (drying), thereby obtaining at least one layer of nanocellulose on at least a part of the surface of the substrate.

[0121] All details, embodiments and preferred embodiments disclosed above in the section related to the first aspect of the invention and in the section related to the second aspect of the invention apply also to the process of the third aspect of the invention.

[0122] The third aspect of the invention is also directed to a process for protecting a surface of a substrate, the process comprising

[0123] (I) applying a mixture comprising nanocellulose and a solvent to a surface of a substrate (to be protected); thereby obtaining a film comprising solvent and nanocellulose on at least a part of the surface of the substrate;

[0124] (II) removing solvent from the film comprising nanocellulose obtained in step (I) (drying), and optionally curing of binder, thereby obtaining at least one layer of nanocellulose on at least a part of the surface of the substrate; wherein the removal of solvent and optionally curing of binder according to step (II) is preferably done by a method selected from the group consisting of infrared heating, microwave heating, conductive heating and mixed forms of two or more of these methods; the process further comprising

[0125] (ill) applying an aqueous medium to the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in (II), thereby obtaining an aqueous film comprising nanocellulose on at least a part of the surface of the substrate;

[0126] (iv) removing the aqueous film comprising nanocellulose obtained in (ill) from the surface of the substrate, thereby obtaining a washed-off aqueous mixture comprising nanocellulose and a substrate, the surface thereof being substantially free of nanocellulose.

[0127] Preferably, the substrate is made of glass and / or metal and has a primary coating on at least one surface, wherein in (I) the mixture comprising nanocellulose and a solvent is applied to the surface of the substrate (to be protected) on top of the primary coating.

[0128] Preferably, the primary coating comprises or is a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti-reflective coating, self-cleaning coating, and mixtures of two or more of these coatings. Preferably, the primary coating comprises or is a low emissivity coating (Low- E coating) and / or a silver (Ag) comprising coating, more preferably the primary coating comprises or is a low emissivity coating. 240826W001

[0129] - 17 -

[0130] A low emissivity coating (low-E coating) has the purpose to reduce heat loss and improve energy efficiency. It may be a hard coating (robust) or a soft coating (more efficient). Low-E coatings consist of microscopically thin layers of metallic materials and / or ceramic materials that specifically reflect heat and allow light to pass through, wherein the metallic and / or ceramic materials are preferably selected from the group consisting of silver (Ag), metal oxide, preferably selected from the group consisting of titanium dioxide (TiO2), zinc oxide (ZnO), tin oxide (SnO2) and mixtures of two or more thereof, silicon nitride, and mixtures of two or more thereof. A protective coating preferably comprises a dielectric layer (e.g., ceramic materials). A reflective coating has the purpose to reduce solar radiation and heat gain. It preferably comprises a metallic and / or a non-metallic material, preferably selected from the group consisting of silver, aluminum, titanium doxide and mixtures of two or more thereof. A sun protection coating preferably comprises one or more, preferably more, layer(s) of silver. Its purpose os for high selectivity and optical quality. An anti-reflec- tive coating has the purpose to minimize glare and reflection, e.g., for showcases or displays. It preferably comprises a material selected from the group consisting of magnesium fluoride (MgF2), silicon dioxide (Si02), titanium oxide (TiO2), silicon nitride (Si3N4), aluminum oxide (AI203), and mixtures of two or more thereof. A self-cleaning coating may be hydrophilic or hydrophobic and has the purpose to break down dirt under UV light and make cleaning easier. A self-cleaning coating is preferably selected from the group consisting of photocatalytic coating (hydrophilic), which preferably comprises titanium dioxide (TiO2), hydrophobic coating (lotus effect), which preferably comprises a nanostructured silicon compound and / or a polysiloxane (e.g., PDMS), hybrid coating, and mixtures of two or more thereof. A photocatalytic coating functions in that under UV light, reactive oxygen radicals are formed which break down organic contaminants. At the same time, the surface becomes superhydrophilic, so that water runs off as a film and takes dirt with it. The effect is preferably permanent, as Ti O2is not consumed as a catalyst. A hydrophobic coating (lotus effect) functions in that micro- and nanostructures create extremely water-repellent surfaces, causing droplets to roll off and take dirt particles with them. A hybrid coating preferably comprises a combination of hydrophilic TiO2layers and organic additives (e.g., silanes, maleic anhydride) to improve adhesion and photocatalytic performance.

[0131] Preferably, step (i) comprises

[0132] (i.1 ) providing an aqueous suspension comprising nanocellulose having a solid content SC(1);

[0133] (1.2) adding water and / or a solvent to the aqueous suspension provided according to (i.1 ), thereby obtaining a mixture comprising nanocellulose, water and optionally a solvent and having a reduced solid content SC(2) with SC(2) < SC(1);

[0134] (1.3) applying the mixture comprising nanocellulose, water and optionally a solvent having solid content SC(2) obtained in (i.2) to a surface of a substrate (to be protected); thereby obtaining a film comprising water, optionally solvent and nanocellulose on at least a part of the surface of the substrate.

[0135] It is preferred that solid content SC(2) is in the range of from 0.1 x SC(1) to 0.9 x SC(1). Preferably, the solid content SC(1) is in the range of from 10 to 20 weight-% based on the total weight of the suspension provided according to (i.1) being 100 weight-%. Preferably, the solid content SC(2) is in the range of from 1 to 10 weight-%, preferably in 240826W001

[0136] - 18 - the range of from 3 to 7 weight-% or in the range of from 1 to 5 weight-%, each based on the total weight of the mixture obtained according to (i.1) being 100 weight-%.

[0137] It is preferred that the nanocellulose provided according to (I) is obtained or obtainable from cellulose fibers, preferably obtained or obtainable by a process as described above in the section related to the first aspect of the invention.

[0138] According to step (1.2) water and / or a solvent is added. Preferably, the solvent comprises a C2 to C5 alcohol preferably ethanol.

[0139] Preferably, the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) comprises at least one binder, wherein the binder is preferably selected from the group consisting of binder based on a polycarboxylic acid, optionally bound to a latex particle, and a polyalcohol (Acrodur®); butanetetracarboxylic acid; modified polyethylene wax (Aquamat® 272N); and mixtures of two or more thereof; wherein the at least one binder is present in the range of from 5 to 50 weight-%, based on the total weight of the mixture being 100 weight-%. In some embodiments, especially when protective coatings are intended, it is preferred that the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) comprises essentially no binder, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are binder based on the total weight of the mixture being 100 weight-%.

[0140] It is preferred that the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) comprises at least one filler, wherein the filler is preferably selected from the group consisting of clay, loam, talc, mica, rock flour, carbon black, silicate, carbonate, oxide, and mixtures of two or more thereof; wherein the at least one filler is present in the range of from 5 to 50 weight-%, based on the total weight of the mixture being 100 weight-%. In some embodiments, especially when protective coatings are intended, it is preferred that the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) comprises essentially no filler, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are filler based on the total weight of the mixture being 100 weight-%

[0141] Preferably, the mixture comprising nanocellulose, water and optionally a solvent is applied to the surface of the substrate in step (I) or (1.3) in a ratio of 0.01 to 1 .0 gram per m2of the surface, more preferably in the range of from 0.02 to 0.5 gram per m2of the surface, more preferably in the range of from 0.05 to 0.2 gram per m2of the surface.

[0142] It is preferred that the mixture comprising nanocellulose, water and optionally a solvent is applied to the surface of the substrate in step (I) or step (1.3) by a method selected from the group consisting of spray coating, doctor blade coating, dip coating, roller coating, painting and mixed forms of two or more of these methods. 240826W001

[0143] - 19 -

[0144] Preferably, the mixture comprising nanocellulose, water and optionally a solvent is applied to the surface of the substrate in step (I) or step (1.3) by a spray process, preferably using one or more spray nozzle(s), preferably at least two spray nozzles.

[0145] The substrate to be coated can, for example, be a glass pane. For sake of illustration, such a glass pane may have the dimensions 3 m x 6 m. However, the edge lengths are not fix an can change. The glass pane may have a thickness in the range of from 1 to 10 mm.

[0146] The glass panes are preferably provided with a primary coating (functionalized surface) on one or both sides. The glass panes are transported via rollers. The nanocellulose spray is applied on the opposite side of the rollers. Usually, the nanocellulose protective layer is only applied to the side(s) of the glass plate that has / have the primary coating.

[0147] Preferably, several spray nozzles are arranged across the width of the substrate to be coated, i.e. the glass pane, which is also advantageous for achieving an even layer of nanocellulose which is also not too thick. Preferably, the spray nozzle(s) are cone spray nozzle(s) (omnidirectional nozzles) or flat spray nozzle(s) or a combination of cone spray nozzle(s) and flat spray nozzle(s), preferably with a nozzle diameter in the range of from 0.5 to 2.5 mm. As an example, spray nozzles can be used, which are usually used for the application of paint layers. The operating pressure should be in the range of from 1.1 to 10 bar, preferably in the range of from 1.2 to 5 bar, more preferably about 2.0 bar.

[0148] Preferably, the at least two spray nozzles are arranged so that their spray patterns (the circular area resulting from the spray cone on the glass surface or the line that results from flat jet nozzles) on the substrate's surface to be coated overlap by < 50 %, preferably by < 25 %, more preferably by < 10 %. By reducing and / or avoiding overlapping, it can be avoided: that zones are created that have more solids and are therefore more difficult to wash off later. that zones are created in which more water is applied that has to be evaporated. If the water cannot be completely evaporated, no dry protective film will form at this point, so that the function of the coating is not given at this point.

[0149] When two or more nozzle(s) are used, they are typically arranged in a so called nozzle bar. The overlap can be adjusted by adjusting the distance of the nozzle bar to the surface to be coated such as the surface of the glass pane, and by adjusting the distance of the nozzles in the nozzle bar to each other.

[0150] To avoid uneven application, it is advantageous to arrange two nozzle bars one after the other, with the nozzles offset by exactly half of the spray cone diameter. This reduces the influence of the overlap.

[0151] Preferably, either the nozzle bar(s) is / are moved or the substrate is moved or both nozzle bar(s) and the substrate are moved, the later preferably in about opposite directions. The expression in "about opposite directions” means that 240826W001

[0152] - 20 - nozzle bar(s) and substrate can move in strictly opposite directions but also under a certain angle, which is preferably in the range of from 1 to 170°, more preferably in the range of from 5 to 45°, more preferably in the range of from 10 to 25°.

[0153] The moist layer on the surface to be coated can consist of individual droplets, some of which still have gaps between the droplets on the surface. Normally, however, a closed surface is achieved with a layer thickness of in the range of from 50 pm to 100 pm. Preferably, with a solid content of the aqueous suspension comprising nanocellulose in the range of from 1 to 5 weight-%, a continuous nanocellulose layer is created on the glass pane after drying. Preferably, the load is in the range of from 1 to 10 g of dried nanocellulose / m2substrate's surface.

[0154] Preferably, step (i) or steps (i.1), (i.2) and (i.3) is / are conducted at a temperature in the range of from 10 to 90°C, more preferably at a temperature in the range of from 15 to 50°C.

[0155] It is preferred that the removal of solvent and optionally curing of a binder is done according to step (ii) by a method selected from the group consisting of infrared heating, microwave heating, conductive heating and mixed forms of two or more of these methods, wherein step (ii) preferably comprises application of near infrared heating.

[0156] In another embodiment, removal of solvent and optionally curing of a binder is done according to step (ii) happens without external application of energy, simply based on the substrate having an elevated temperature (residual heat of the substrate, for example, of a glass pane), wherein an elevated temperature means a temperature of the substrate in the range of from 15 to 100°C, preferably in the range of from 20 to 90°C, more preferably in the range of from > 50°C to 80°C.

[0157] Preferably, step (ii) is conducted at a temperature in the range of from 10 to 350°C, wherein step (ii) may comprise an initial solvent removal step (ii.1 ) and a post-drying step (ii.2).

[0158] Regarding post-drying step (ii.2), it is important that it does not get too warm to prevent the nanocellulose from decomposing. This means that the temperature in the nanocellulose comprising layer must not exceed 200°C. Nevertheless, drying at significantly higher temperatures is possible, as the evaporating solvent, for example, water has a cooling effect on the surface, i.e. drying at a temperature of > 200°C is possible as long as solvent is present in the layer to be dried. For example, a post-drying step (ii.2) under an infrared lamp with peak temperatures of up to 370°C over a short period of time (< 10s), is possible and has no negative impact on the nanocellulose layer. When (ii.1 ) and / or (ii.2) are conducted with NIR emitters, it is also important that the nanocellulose layer is not too thick, i.e. not thicker than 100 m, as otherwise a dry top layer will form first with a solvent comprising liquid mixture below, which will make it difficult for solvent to diffuse further to and through the top layer, which under unfavorable circumstances, can cause the solvent under the dried top layer to evaporate and create a cracked surface.

[0159] In some embodiments, no cracking occurs when the residual heat of the substrate such as the glass pane is used for drying, as the nanocellulose begins to dry at the substrate-nanocellulose interface. It is therefore advantageous. It is 240826W001

[0160] - 21 - advantageous to remove any fumes formed during (ii .1 ) and / or (ii.2) in order to support the solvent removal / drying process and to be able to condense the solvent.

[0161] In some embodiments, when an external heat source(s) such as a NIR heater is / are used, either the heat source(s) is / are moved or the substrate is moved or both heat source(s) and the substrate are moved, the later preferably in about opposite directions. The expression in "about opposite directions” means that heat source(s) and substrate can move in strictly opposite directions but also under a certain angle, which is preferably in the range of from 1 to 170° more preferably in the range of from 5 to 45°, more preferably in the range of from 10 to 25°.

[0162] In other embodiments, when removal of solvent and optionally curing of a binder is done according to step (ii) or (ii.1) and / or post-drying of (ii.2) is / are done without external application of energy, simply based on the substrate having an elevated temperature, the substrate having an elevated temperature is preferably moved during (ii.1) and / or (ii.2), which offers the advantage that the the heat source (pane) is also moved. Preferably, (ii.1 ) and / or (ii.2), are carried out for < 40 seconds. The temperature of the substrate should be as high as possible, i.e. ideally in the range of from > 50 to 80°C. During post-drying using NIR heater, a lot of heat energy must be introduced into the surface in a short time, as the NIR area is limited and thus the residence time in the NIR radiation range.

[0163] It is preferred that the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in step (ii) has a thickness in the range of from 1 to 1000 m, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 10 to 50 pm, more preferably in the range of from 10 to 40 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer. In some embodiments, especially when protective coatings are intended, it is preferred that the layer of nanocellulose has a thickness in the range of from 1 to 1000 pm, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer.

[0164] Preferably, the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in step (ii) has a hardness of > 50 MPa, more preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0165] It is preferred that the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in step (ii) has an Young's modulus of > 5000 MPa, more preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1 mN.

[0166] Preferably, the process further comprises: 240826W001

[0167] - 22 -

[0168] (iii) applying an aqueous medium to the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in (ii), thereby obtaining an aqueous film comprising nanocellulose on at least a part of the surface of the substrate;

[0169] (iv) removing the aqueous film comprising nanocellulose obtained in (iii) from the surface of the substrate, thereby obtaining a washed-off aqueous mixture comprising nanocellulose and a substrate, the surface thereof being substantially free of nanocellulose.

[0170] "Substantially free of nanocellulose” means that there is less than 100 mg, more preferably less than 10 mg, of nanocellulose still present per m2of the substrate's surface. Preferably, upon visual inspection, no visible traces remain the substrate's surface.

[0171] Any primary coating present on the substrate's surface is unaffected by the treatment steps (I), (II) as well as (iii) and (iv), i.e. is still present in undamaged form after step (iv).

[0172] As the applied protective coating is used, for example, for protecting the substrate during transport, especially the steps (iii) and (iv) can be conducted with a certain time gap in-between step (II) and steps (iii), (iv). Steps (iii) and (iv) can be carried out sequentially or at least partially simultaneously.

[0173] Preferably, removing the aqueous film comprising nanocellulose in step (iv) is done mechanically and / or by washing with an aqueous medium. It is preferred that the aqueous medium of (iii) comprises at least 98 weight-%, more preferably at least 99 weight-%, more preferably at least 99.5 weight-%, more preferably 100 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

[0174] As indicated above, the layer of nanocellulose on at least a part of the surface of the substrate has a high resistance against mechanical impact such as scratching. As the nanocellulose is however hydrophilic, the layer once contacted with water soaks up the water almost spontaneously, which results in a loosening of the fiber composite structure and the complete nanocellulose can be washed off without much effort.

[0175] Preferably, steps (iii) and / or, preferably and (iv) are carried out on an industrial scale in substrate washing machine. The washing system is designed in such a way that the substrate is guided into the washing zone via a roller conveyor. In the washing zone, the substrate is moved through under a scrubbing device which comprises one or more rotating brush(es). The brush(es) is / are preceded by a nozzle strip, which comprises one or more nozzle(s), for example 10 nozzles of 4mm diameter each per 0.3 m width of the substrate. In some embodiments, round brushes with a diameter of at least 60 mm are installed in the washing zone. The circumferential speed of the brushes is adjustable between 1 and 20 m / s. In front of the round brush(es), an aqueous medium is applied as evenly as possible via spraying from the nozzle(s). The water is spontaneously absorbed by the nanocellulose layer, so that it becomes soft, thereby obtaining an aqueous film comprising nanocellulose on at least a part of the surface of the substrate, which is then removed by the rotating brush(es). 240826W001

[0176] - 23 -

[0177] In some preferred embodiments, the rotating brush(es) are spiral brush(es), which allow the removal of aqueous medium and detached impurities as well (mainly the washed off nanocellulose layer). Spiral brushes are round brushes on which the individual pairs of tufts are arranged in such a staggered manner that they function like a screw conveyor.

[0178] The speed at which the substrate is transferred through the washing system is preferably in the range of from 0.1 to 0.5 m / s, more preferably in the range of from 0.25 to 0.4 m / s.

[0179] In some preferred embodiments, the overlap of the brushes should be about 1 mm, meaning that the brushes rest on the surface to some extent. For example, if the radius of the brushes is 80 mm, then the distance of the center of the brush shaft to the substrate's surface should be 79 mm.

[0180] The brush material is preferably a polymeric material, more preferably selected from the group consisting of polyamide (PA), polyamide 6 (PA6), polyamide 6.6 (PA6.6) and mixtures or mixed polymers of two or more thereof.

[0181] Preferably, there is a resident time period between application of the aqueous medium according to (iii) and start of the removal of (iv), i.e. start of the washing process through the rotating brush(es), which is preferably in the range of from 0.1 to 10 s, more preferably in the range of from 0.8 to 2 s. Preferably, the volume of the aqueous medium applied in (iii) is more than 20 l / min per m width of the nozzle bar, more preferably be in the range of from 8 to 40 1 / min per m width of the nozzle bar.

[0182] In some preferred embodiments, step (iv) comprises

[0183] (iv.1 ) detaching the aqueous film comprising nanocellulose obtained in (iii) from the surface of the substrate via one or more rotating brush(es),

[0184] (iv.2) removing the detached aqueous film comprising nanocellulose obtained in (i.v) from the surface of the substrate via one or more scraper(s), thereby obtaining a washed-off aqueous mixture comprising nanocellulose and a substrate, the surface thereof being substantially free of nanocellulose.

[0185] Ideally, there should be one or more scraper(s) after the brush(es), in order to wipe off the aqueous mixture comprising nanocellulose from the substrate's surface.

[0186] 4thaspect - Aqueous mixture

[0187] A fourth aspect of the invention relates to an aqueous mixture comprising nanocellulose, preferably obtainable or obtained by the process of the third aspect of the invention as described above, preferably in step (iv) of said process. 240826W001

[0188] - 24 -

[0189] All details, embodiments and preferred embodiments disclosed in the section related to the first aspect of the invention, in the section related to the second aspect of the invention and in the section related to the third aspect of the invention also apply to the fourth aspect of the invention.

[0190] Preferably, the aqueous mixture comprising nanocellulose further comprises at least one binder or a reaction product of at least one binder and / or at least one filler. In some embodiments, especially when protective coatings are intended, the aqueous mixture comprising nanocellulose comprises essentially neither a binder nor a reaction product of a binder and / or a filler, wherein the aqueous mixture preferably comprises less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm, of binder and / or reaction product of a binder and / or a filler, based on the total weight of the aqueous mixture being 100 weight-%.

[0191] 5thaspect - aqueous mixture with / without further components

[0192] A fifth aspect of the invention relates to an aqueous mixture comprising nanocellulose, further comprising at least one binder or a reaction product of at least one binder and / or at least one filler. In some embodiments, especially when protective coatings are intended, the fifth aspect of the invention relates to an aqueous mixture comprising nanocellulose, which essentially comprises neither a binder nor a reaction product of a binder and / or a filler, wherein the aqueous mixture preferably comprises less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm, of binder and / or reaction product of a binder and / or a filler, based on the total weight of the aqueous mixture being 100 weight-%. All details, embodiments and preferred embodiments disclosed in the section related to the first aspect of the invention, in the section related to the second aspect of the invention, in the section related to the third aspect of the invention and in the section related to the fourth aspect of the invention also apply for the fifth aspect of the invention.

[0193] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The coated substrate of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The coated substrate of any one of embodiments 1 , 2, 3 and 4". Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.

[0194] 1 . A coated substrate, comprising a substrate, said substrate having at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate. 240826W001

[0195] - 25 -

[0196] 2. The coated substrate of embodiment 1 , wherein the substrate comprises or is made of, optionally coated, glass and / or metal.

[0197] 3. A coated substrate according to embodiment 1 or 2, comprising a substrate made of glass and / or metal, said substrate having a primary coating on at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate, on top of the primary coating.

[0198] 4. The coated substrate of embodiment 3, wherein the primary coating comprises or is a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti-reflective coating, self-cleaning coating, and mixtures of two or more of these coatings.

[0199] 5. The coated substrate of any one of embodiments 1 to 4, wherein the layer of nanocellulose has a thickness in the range of from 1 to 1000 m, preferably in the range of from 5 to 800 pm, more preferably in the range of from 10 to 50 pm, more preferably in the range of from 10 to 40 pm, preferably determined by byprofilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer or a thickness in the range of from 1 to 1000 pm, preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by pro- filometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer.

[0200] 6. The coated substrate of any one of embodiments 1 to 5, wherein the layer of nanocellulose has a hardness of > 50 MPa, preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0201] 7. The coated substrate of any one of embodiments 1 to 6, wherein the layer of nanocellulose has an Young's modulus of > 5000 MPa, preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0202] 8. The coated substrate of any one of embodiments 1 to 7, wherein the nanocellulose is obtained or obtainable from cellulose fibers.

[0203] 9. The coated substrate of any one of embodiments 1 to 8, wherein the nanocellulose is obtained or obtainable from cellulose fibers, preferably from a polymeric material comprising cellulose fibers, by a process for preparing nanocellulose from a polymeric material comprising cellulose fibers, the process comprising: 240826W001

[0204] - 26 -

[0205] (i) Providing pieces p1 of the polymeric material comprising cellulose fibers;

[0206] (II) Shredding the pieces p1 provided according to (I) in n shredding devices SD(i) wherein n is an integer with n>1 and 1=1 ...n, thereby obtaining pieces p2, which comprise cellulose fibers;

[0207] (ill) Preparing an aqueous mixture comprising the pieces p2 at a temperature T 1 and adjusting the temperature of the aqueous mixture comprising the pieces p2 to a temperature T2 with T2 > T1 , thereby obtaining an aqueous mixture comprising the pieces p2 and having temperature T2;

[0208] (iv) Introducing at least one enzyme capable of degrading cellulose (cellulase) into the aqueous mixture obtained according to (ill), thereby obtaining an aqueous mixture comprising the pieces p2 and at least one enzyme, wherein the aqueous mixture has temperature T2;

[0209] (v) Milling the aqueous mixture obtained according to (iv) in a milling device MD(1), thereby obtaining an aqueous mixture comprising the at least one enzyme and milled pieces p3, which comprise at least partially degraded cellulose fibers;

[0210] (vi) Milling the aqueous mixture obtained according to (v) in a stirred media mill SMM, thereby obtaining an aqueous mixture comprising the at least one enzyme and nanocellulose (at least partially degraded and / or at least partially defibrillated cellulose).

[0211] 10. The coated substrate of any one of embodiments 1 to 9, wherein the layer of nanocellulose further comprises at least one binder, wherein the binder is preferably selected from the group consisting of binder based on a polycarboxylic acid, optionally bound to a latex particle, and a polyalcohol (Acrodur®); butanetetracarboxylic acid; modified polyethylene wax (Aquamat® 272N); and mixtures of two or more thereof, wherein the at least one binder is present in the range of from 5 to 50 weight-%, based on the total weight of the layer of nanocellulose being 100 weight-%; or the coated substrate of any one of embodiments 1 to 9, wherein the layer of nanocellulose comprises essentially no binder, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are binder based on the total weight of the layer of nanocellulose being 100 weight-%.

[0212] 11 . The coated substrate of any one of embodiments 1 to 10, wherein the layer of nanocellulose further comprises at last one filler, wherein the filler is preferably selected from the group consisting of clay, loam, talc, mica, rock flour, carbon black, silicates, carbonates, oxides, and mixtures of two or more thereof; wherein the at least one filler is present in the range of from 5 to 50 weight-%, based on the total weight of the layer of nanocellulose being 100 weight-%, or wherein the layer of nanocellulose essentially comprises no filler, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight- ppm of the layer of nanocellulose are filler, based on the total weight of the layer of nanocellulose being 100 weight-%.

[0213] 12. The coated substrate of any one of embodiments 1 to 11, wherein the layer of nanocellulose further comprises at least one C16-C18 fatty alcohol polyethylene glycol-ether, preferably present in up to 5 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%. 240826W001

[0214] - 27 -

[0215] 13. The coated substrate of any one of embodiments 1 to 12, wherein the layer of nanocellulose further comprises at least one non-ionic surfactant, preferably present in up to 1 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%.

[0216] 14. The coated substrate of any one of embodiments 1 to 13, wherein the layer of nanocellulose is removable by addition of an aqueous medium, wherein the aqueous medium comprises at least 98 weight-%, more preferably at least 99 weight-%, more preferably at least 99.5 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

[0217] 15. Use of nanocellulose as, preferably removable, protective coating on a surface of a glass and / or metal substrate which has a primary coating on at least a part of its surface.

[0218] 16. The use of embodiment 15, wherein the nanocellulose is obtained or obtainable from cellulose fibers, preferably obtained or obtainable by a process of embodiment 9.

[0219] 17. The use of embodiment 15 or 16, wherein the nanocellulose coating further comprises at least one binder, wherein the binder is preferably selected from the group consisting of binder based on a polycarboxylic acid, optionally bound to a latex particle, and a polyalcohol (Acrodur®); butanetetracarboxylic acid; modified polyethylene wax (Aquamat® 272N); and mixtures of two or more thereof, wherein the at least one binder is present in the range of from 5 to 50 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%; or wherein the nanocellulose coating comprises essentially no binder, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are binder based on the total weight of the nanocellulose coating being 100 weight-%.

[0220] 18. The use of any one of embodiments 15 to 17, wherein the nanocellulose coating further comprises at last one filler, wherein the filler is preferably selected from the group consisting of clay, loam, talc, mica, rock flour, carbon black, silicate, carbonate, oxide and mixtures of two or more thereof; wherein the at least one filler is present in the range of from 5 to 50 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%-%, or wherein the layer of nanocellulose essentially comprises no filler, preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm of the layer of nanocellulose are filler, based on the total weight of the nanocellulose coating being 100 weight-%.

[0221] 19. The use of any one of embodiments 15 to 18, wherein the nanocellulose coating further comprises at least one C16-C18 fatty alcohol polyethylene glycol-ether, preferably present in up to 5 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%. 240826W001

[0222] - 28 -

[0223] 20. The use of any one of embodiments 15 to 19, wherein the nanocellulose coating further comprises at least one non-ionic surfactant, preferably present in up to 1 weight- %, based on the total weight of the nanocellulose coating being 100 weight-%.

[0224] 21. The use of any one of embodiments 15 to 20, wherein the nanocellulose coating is removable by addition of an aqueous medium, wherein the aqueous medium comprises at least 98 weight-%, more preferably at least 99 weight-% more preferably at least 99.5 weight-% more preferably 100 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

[0225] 22. The use of any one of embodiments 15 to 21, wherein the nanocellulose coating has a thickness in the range of from 1 to 1000 m, preferably in the range of from 5 to 800 pm, more preferably in the range of from 10 to 50 pm, more preferably in the range of from 10 to 40 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer or a thickness in the range of from 1 to 1000 pm, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer.

[0226] 23. The use of any one of embodiments 15 to 22, wherein the nanocellulose coating has a hardness of > 50 MPa, preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0227] 24. The use of any one of embodiments 15 to 23, wherein the nanocellulose coating has an Young's modulus of > 5000 MPa, preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0228] 25. A process for preparing a protective coating on a substrate, the process comprising

[0229] (I) applying a mixture comprising nanocellulose and a solvent to a surface of a substrate (to be protected); thereby obtaining a film comprising solvent and nanocellulose on at least a part of the surface of the substrate;

[0230] (II) removing solvent from the film comprising nanocellulose obtained in step (I) (drying), thereby obtaining at least one layer of nanocellulose on at least a part of the surface of the substrate.

[0231] 26. The process of embodiment 25, wherein (I) comprises

[0232] (1.1) providing an aqueous suspension comprising nanocellulose having a solid content SC(1); 240826W001

[0233] - 29 -

[0234] (1.2) adding water and / or a solvent to the aqueous suspension provided according to (i.1 ), thereby obtaining a mixture comprising nanocellulose, water and optionally a solvent and having a reduced solid content SC(2) with SC(2) < SC(1);

[0235] (1.3) applying the mixture comprising nanocellulose, water and optionally a solvent having solid content SC(2) obtained in (i.2) to a surface of a substrate (to be protected); thereby obtaining an film comprising water, optionally solvent and nanocellulose on at least a part of the surface of the substrate.

[0236] 27. The process of embodiment 26, wherein solid content SC(2) is in the range of from 0.1 x SC(1) to 0.9 x SC(1).

[0237] 28. The process of embodiment 26 or 27, wherein solid content SC(1 ) is in the range of from 10 to 20 weight-% based on the total weight of the suspension provided according to (1.1) being 100 weight-%.

[0238] 29. The process of any one of embodiments 21 to 23, wherein solid content SC(2) is in the range of from 1 to 10 weight-%, preferably in the range of from 3 to 7 weight-%, or in the range of from 1 to 5 weight-%, based on the total weight of the mixture obtained according to (1.1) being 100 weight-%.

[0239] 30. The process of any one of embodiments 25 to 29, wherein the nanocellulose provided according to (I) is obtained or obtainable from cellulose fibers, preferably obtained or obtainable by a process of embodiment 7.

[0240] 31 . The process of any one of embodiments 25 to 30, wherein the solvent comprises a C2 to C5 alcohol preferably ethanol.

[0241] 32. The process of any one of embodiments 25 to 31 , wherein the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) comprises at least one binder, wherein the binder is preferably selected from the group consisting of binder based on a polycarboxylic acid, optionally bound to a latex particle, and a polyalcohol (Acrodur®); butanetetracarboxylic acid; modified polyethylene wax (Aquamat® 272N); and mixtures of two or more thereof; wherein the at least one binder is present in the range of from 5 to 50 weight- %, based on the total weight of the mixture being 100 weight-%; or wherein the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) essentially comprises no binder, preferably less than

[0242] 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm of the mixture are binder, based on the total weight of the mixture being 100 weight-%.

[0243] 33. The process of any one of embodiments 25 to 32, wherein the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) comprises at least one filler, wherein the filler is preferably selected from the group consisting of clay, loam, talc, mica, rock flour, carbon black, silicate, carbonate, oxide, and mixtures of two or more thereof; wherein the at least one filler is present in the range of from 5 to 50 weight-%, based on the total weight of the mixture being 100 weight-%-; or wherein the mixture comprising nanocellulose, water and optionally a solvent applied in (I) or (1.3) essentially comprises no filler, preferably less than 1 240826W001

[0244] - 30 - weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm of the mixture are filler, based on the total weight of the mixture being 100 weight-%.

[0245] 34. The process of any one of embodiments 25 to 33, wherein the mixture comprising nanocellulose, water and optionally a solvent is applied to the surface of the substrate in step (i) or (i.3) in a ratio of 0.01 to 1 .0 gram per m2of the surface, preferably in the range of from 0.02 to 0.5 gram per m2of the surface, more preferably in the range of from 0.05 to 0.2 gram per m2of the surface.

[0246] 35. The process of any one of embodiments 25 to 34, wherein the mixture comprising nanocellulose, water and optionally a solvent is applied to the surface of the substrate in step (i) or step (i.3) by a method selected from the group consisting of spray coating, doctor blade coating, dip coating, roller coating, painting and mixed forms of two or more of these methods.

[0247] 36. The process of any one of embodiments 25 to 35, wherein the mixture comprising nanocellulose, water and optionally a solvent is applied to the surface of the substrate in step (i) or step (i.3) by a spray process, preferably using one or more spray nozzle(s), preferably at least two spray nozzles.

[0248] 37. The process of embodiment 36, wherein the spray nozzle(s) are cone spray nozzle(s) (omnidirectional nozzles) or flat spray nozzle(s) or a combination of cone spray nozzle(s) and flat spray nozzle(s).

[0249] 38 The process of embodiment 37, wherein the at least two spray nozzles are arranged so that their spray patterns (the circular area resulting from the spray cone on the glass surface or the line that results from flat jet nozzles) on the substrate's surface to be coated overlap by <50 %, preferably by less then 25 %, more preferably by < 10 %.

[0250] 39. The process of any one of embodiments 25 to 38, wherein step (i) or steps (i.1), (i.2) and (i.3) is / are conducted at a temperature in the range of from 10 to 90°C, preferably at a temperature in the range of from 15 to 50°C.

[0251] 40. The process of any one of embodiments 25 to 39, wherein the removal of solvent and optionally curing of a binder is done according to step (ii) by a method selected from the group consisting of infrared heating, microwave heating, conductive heating and mixed forms of two or more of these methods, wherein step (ii) preferably comprises application of near infrared heating.

[0252] 41 . The process of any one of embodiments 25 to 40, wherein step (ii) is conducted at a temperature in the range of from 10 to 350°C.

[0253] 42. The process of any one of embodiments 25 to 41 , wherein the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in step (ii) has a thickness in the range of from 1 to 1000 m, 240826W001

[0254] - 31 - preferably in the range of from 5 to 800 m, more preferably in the range of from 10 to 50 pm, more preferably in the range of from 10 to 40 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer or a thickness in the range of from 1 to 1000 pm, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer.

[0255] 43. The process of any one of embodiments 25 to 42, wherein the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in step (II) has a hardness of > 50 MPa, preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0256] 44. The process of any one of embodiments 25 to 43, wherein the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in step (ii) has an Young's modulus of > 5000 MPa, preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

[0257] 45. The process of any one of embodiments 25 to 44, further comprising:

[0258] (iii) applying an aqueous medium to the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in (ii), thereby obtaining an aqueous film comprising nanocellulose on at least a part of the surface of the substrate;

[0259] (iv) removing the aqueous film comprising nanocellulose obtained in (iii) from the surface of the substrate, thereby obtaining a washed-off aqueous mixture comprising nanocellulose.

[0260] 46. The process of embodiment 45, wherein removing the aqueous film comprising nanocellulose in step (iv) is done mechanically and / or by washing with an aqueous medium.

[0261] 47. The process of embodiment 45 or 46, wherein the aqueous medium of (iii) comprises at least 98 weight-%, more preferably at least 99 weight-%, more preferably at least 99.5 weight-%, more preferably 100 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

[0262] 48. An aqueous mixture comprising nanocellulose, preferably obtainable or obtained by the process of any one of embodiments 25 to 47, preferably in step (iv) of embodiment 47.

[0263] 49. An aqueous mixture comprising nanocellulose according to embodiment 48, further comprising at least one binder or a reaction product of at least one binder and / or at least one filler or an aqueous mixture comprising 240826W001

[0264] - 32 - nanocellulose according to embodiment 48, and essentially neither binder nor a reaction product of a binder and / or a filler, wherein preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm, are binder and / or reaction product of binder and / or filler, based on the total weight of the aqueous mixture being 100 weight-%.

[0265] 50. An aqueous mixture comprising nanocellulose, further comprising at least one binder or a reaction product of at least one binder and / or at least one filler or an aqueous mixture comprising nanocellulose according to embodiment 48, and essentially neither binder nor a reaction product of a binder and / or a filler, wherein preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight- ppm, are binder and / or reaction product of binder and / or filler, based on the total weight of the aqueous mixture being 100 weight-%.

[0266] The present invention is further illustrated by the following reference examples, comparative examples, and examples.

[0267] Examples

[0268] 1 . Preparation of coatings

[0269] Aqueous suspensions comprising nanocellulose were prepared based on nanocellulose obtained from textile and nanocellulose obtained from pulp, and applied via doctor blade coating to an aluminum substrate. Details are listed in Table 1 (Examples E1, E2, E3). For comparison, a clear water-based acrylic lacquer based on acrylic resins was also applied via doctor blade coating to an aluminum substrate as indicated in Table 1 (Comparative Example CE1).

[0270] Table 1

[0271] Compositions of coatings of Examples E1 , E2, E3 and of Comparative Example CE1 as well as thicknesses of the applied (wet) coatings 240826W001

[0272] - 33 -

[0273] Drying was done for sample E1 at 170°C under air, CE1, E2 and E3 were dried at 60°C under air.

[0274] 2 Thickness and mechanical properties

[0275] The thickness of the dry coatings of Comparative Example CE1 and of inventive Examples E1, E2 and E3 was analysed with a profilometer (Dektak XT 2D Stylus Profilometer, Bruker), according to ISO 25178 using a tip radius 2pm, a force of 5mg, and with a profile length of 30 mm. . The E Modulus and the hardness of the surfaces were determined by nanoindentation based on cryo microtome cuts (T -80°C), using a Berkovich tip and a load of 1mN. The results are summarized in Table 2.

[0276] Table 2

[0277] Thicknesses and properties of (dry) coatings of Examples E1, E2, E3 and of Comparative Example CE1

[0278] "- - " E2 could not be measured as no free film could be prepared due to varying thickness.

[0279] It was found that, even if comparable thicknesses of dry coatings were achieved, that Young's modulus and hardness were much more favorable for the nanocellulose based coatings. Scratch measurements were made for all samples with a nanoindenter (Nano Indenter ® G200 from KLA, X-head) using a conical tip 2 pm / 90°. The measurements were done with a scratch length of 3000 pm, a scratch velocity of 50 pm / s and a maximum scratch load of 100 mN. The scratch measurements were done in three steps with a step 1 being a scan of the original surface, step 2 being a scan with ramping scratch load and step 3 being a scan of the residual deformation. All measurements were repeated threefold or fourfold (V1 to V3 and V1 to V4 respectively). The results regarding displacement into the surface and the residual depth at scratch with load of 80 mN are summarized in Table 3 below, wherein the residual depth was calculated as the difference between the original surface scan of step 1 and the residual deformation scan of step 3.

[0280] Table 3 240826W001

[0281] - 34 -

[0282] Results of scratch measurements

[0283] It could be seen that the acrylic resin based coating of comparative example CE2 was scratched far deeper than the coatings of the inventive examples E1, E2 and E3, i.e. the inventive coatings were more resistant against scratching. Furthermore, also the residual depth achieved for the acrylic resin based coating of CE2 was much deeper than that of the inventive examples E1 , E2 and E3 indicating also that the inventive coatings were more resistant against scratching.

[0284] 3. Further examples

[0285] Example 4: Preparation of nanocellulose coating on glass pane (substrate) and subseguent removal

[0286] An aqueous suspension comprising 1 weight-% of nanocellulose (prepared based on nanocellulose obtained from textile and nanocellulose obtained from pulp) was applied to a glass pane (substrate) in a width of 150 mm using a 0.25 mm nozzle. The glass pane was moved, wherein the transportation speed of the glass pane under the nozzle was 150 mm / s. One passage was made, i.e. only one spray layer of nanocellulose was applied. The temperature of the glass pane was 50°C. The drying time was about 15 seconds. The layer thickness after drying was approximately 2 pm.

[0287] The nanocellulose layer was then removed, wherein the glass pane was moved through under a rotating brush. The round brush was preceded by a nozzle strip with 10 nozzles of 4 mm diameter. Round brushes with a diameter of 80 mm were installed in the washing zone, wherein the brushes had an overlap with the substrate's surface of 1 mm, i.e. the distance between the center of the round brushes and the substrate's surface were 39 mm. The circumferential speed of the brushes was 2.1 m / s, i.e. the round brushes were rotated with 500U / min. In front of the round brush, water was applied as evenly as possible via a spray bar, wherein the water was applied with 3600ml / min*m substrate's surface. The water was spontaneously absorbed by the nanocellulose layer, so that it became soft and could be removed by the round brushes. 240826W001

[0288] - 35 -

[0289] To check the washing result, photos were taken with an edge light in front of a black background, which made the smallest defects and fingerprints visible with the nanocellulose layer present on the glass pane and after the removal. Upon visual inspection, an even coating layer was apparent before the removal and no more residues were found on the substrate's surface, i.e. the photos after removal of the nanocellulose coating were black in total.

[0290] Example 5: Preparation of nanocellulose coating on glass pane (substrate) and subseguent removal

[0291] An aqueous suspension comprising 2 weight-% of nanocellulose (prepared based on nanocellulose obtained from textile and nanocellulose obtained from pulp) was applied to a glass pane (substrate) in a width of 150 mm using a 0.75 mm nozzle. The glass pane was moved, wherein the transportation speed of the glass plate under the nozzle was 150 mm / s. One passage was made, i.e. only one spray layer of nanocellulose was applied. The temperature of the glass pane was 40°C. It was dried using NIR heater. The distance of the NIR heater to the glass plate was 6 mm. The temperature on the surface of the NIR radiator was 370°C. The drying time was about 10 seconds. The layer thickness after drying was approximately 5 pm.

[0292] The nanocellulose layer was then removed, wherein the glass pane was moved through under a rotating brush. The round brush was preceded by a nozzle strip with 10 nozzles of 4 mm diameter per 0.3 m substrate's width. Round brushes with a diameter of 80 mm were installed in the washing zone, wherein the brushes had an overlap with the substrate's surface of 1 mm, i.e. the distance between the center of the round brushes and the substrate's surface were 39 mm. The circumferential speed of the brushes was 2.1 m / s, i.e. the round brushes were rotated with 500U / min. In front of the round brush, water was applied as evenly as possible via a spray bar, wherein the water was applied with 3600ml / min. The water was spontaneously absorbed by the nanocellulose layer, so that it became soft and could be removed by the round brushes.

[0293] To check the washing result, photos were taken with an edge light in front of a black background, which made the smallest defects and fingerprints visible with the nanocellulose layer present on the glass pane and after the removal. Upon visual inspection, an even coating layer was apparent before the removal and no more residues were found on the substrate's surface, i.e. the photos after removal of the nanocellulose coating were black in total.

[0294] Example 6 Preparation of nanocellulose coating on glass pane with primary low emissivity coating on a surface (substrate) and testing of abrasion resistance and scratch resistance

[0295] Glass panes with primary low emissivity coating on a surface were coated with an aqueous suspension comprising nanocellulose, optionally binder and / or filler, as described in 1 (Preparation of coatings), wherein the compositions of the aqueous suspension comprising the nanocellulose used for the coating are listed below in Table 4. 240826W001

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[0297] Table 4

[0298] Composition of aqueous suspension

[0299] Each glass pane (having primary low emissivity coating on a surface) had a temperature as indicated in Table 5 below and the aqueous suspension comprising nanocellulose was dried using a NIR heater, optionally combined with air drying. The distance of the NIR heater to the glass plate was as indicated in Table 5. The temperature on the surface of the NIR radiator was 370°C. The drying time and the layer thickness after drying were as indicated in Table 5.

[0300] The dried nanocellulose layer was characterized for its abrasion behavior. For this purpose, an abrasion test was performed in that a cantilever arm was used, which guided a piece of cardboard with a base area of 32 cm2over the coated surface. The piece of cardboard was evenly loaded with a load of 400 g to create an even distribution of pressure on the nanocellulose coated surface. The surface pressure was thus 0.4kg*9.81 m / s2 / 0.0032m2= 1226 N / m2. The piece of cardboard, which was loaded with weight, was pushed 36 cm over the coated surface per stroke. A total of 200 forward and backward movements were performed. This meant that the piece of cardboard was pulled 400 x 36 cm over the coated surface per test. The stroke frequency was 10 double strokes per minute. This meant that the test was finished after 20 minutes. The abrasion resistance was qualitatively rated as "pass” or "fail”, wherein the results are listed below in Table 5. The term "pass" with respect to the result of the abrasion test signified that the nanocellulose coating layer remained intact after 400 strokes, each stroke measuring 36 cm, whereas "fail” signified that the nanocellulose coating layer was damaged after 400 strokes, each stroke measuring 36 cm.

[0301] Furthermore, the scratch resistance was determined in accordance with DIN 55656 using a Zehntner hardness tester type ZHT 2092 with a test tip of 0.75 mm, wherein the results are listed below in Table 5. able 5 hickness of dry layer, drying conditions and abrasion as well as scratch behavior he data showed that even thin nanocellulose layers demonstrated significant abrasion resistance. However, the samples containing filler particles, specifically ID-2024-0046 nd ID-2024-0059, did not pass the abrasion test as the filler particles caused the coating to tear apart.

Claims

1. 240826W001- 38 -Claims1 . A coated substrate, comprising a substrate comprising or consisting of glass and / or metal, said substrate having a primary coating on at least one surface; and at least one, preferably removable, layer of nanocellulose on at least a part of said at least one surface of the substrate, on top of the primary coating.

2. The coated substrate of claim 1 , wherein the primary coating comprises or is a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti- reflective coating, self-cleaning coating, and mixtures of two or more of these coatings.

3. The coated substrate of claim 1 or 2, wherein the layer of nanocellulose has a thickness in the range of from 1 to 1000 m, more preferably in the range of from 5 to 800 pm, more preferably in the range of from 1 to 10 pm, more preferably in the range of from 1 to 5 pm, preferably determined by profilometry, preferably according to ISO 25178 by using a profilometer, preferably a Dektak XT 2D Stylus Profilometer.

4. The coated substrate of any one of claims 1 to 3, wherein the layer of nanocellulose has a hardness of > 50 MPa, preferably in the range of from 50 to 200 MPa, more preferably in the range of from 60 to 170 MPa, wherein the hardness is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

5. The coated substrate of any one of claims 1 to 4, wherein the layer of nanocellulose has an Young's modulus of > 5000 MPa, preferably in the range of from 5000 to 15000 MPa, more preferably in the range of from 8000 to 10000 MPa, wherein the Young's modulus is preferably determined by nanoindentation, more preferably by nanoindentation according to ISO 14577-1 using a Berkovich tip and a load of 1mN.

6. The coated substrate of any one of claims 1 to 5, wherein the nanocellulose is obtained or obtainable from cellulose fibers, preferably from a polymeric material comprising cellulose fibers.

7. The coated substrate of any one of claims 1 to 6, wherein the layer of nanocellulose is removable by addition of an aqueous medium, wherein the aqueous medium comprises at least 98 weight-%, more preferably at least 99 weight-%, more preferably at least 99.5 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

8. Use of nanocellulose as, preferably removable, protective coating on a surface, wherein the surface to be protected is preferably the surface of a substrate, which comprises or is made of, glass and / or metal, the substrate having a primary coating on at least one surface, wherein the primary coating preferably comprises or is240826W001- 39 - a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti-reflective coating, self-cleaning coating, and mixtures of two or more of these coatings.

9. The use of claim 8, wherein the nanocellulose is obtained or obtainable from cellulose fibers, preferably from a polymeric material comprising cellulose fibers.

10. The use of claim 8 or 9, wherein the nanocellulose coating further comprises at least one binder, wherein the binder is preferably selected from the group consisting of binder based on a polycarboxylic acid, optionally bound to a latex particle, and a polyalcohol (Acrodur®); butanetetracarboxylic acid; modified polyethylene wax (Aquamat® 272N); and mixtures of two or more thereof, wherein the at least one binder is present in the range of from 5 to 50 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%; or wherein the nanocellulose coating essentially comprises no binder, wherein preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are binder, based on the total weight of the nanocellulose coating being 100 weight-%. and / or wherein the nanocellulose coating further comprises at last one filler, wherein the filler is preferably selected from the group consisting of clay, loam, talc, mica, rock flour, carbon black, silicate, carbonate, oxide and mixtures of two or more thereof; wherein the at least one filler is present in the range of from 5 to 50 weight-%, based on the total weight of the nanocellulose coating being 100 weight-%, or wherein the nanocellulose coating essentially comprises no filler, wherein preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are filler, based on the total weight of the nanocellulose coating being 100 weight-%.11 . The use of any one of claims 8 to 10, wherein the nanocellulose coating is removable by addition of an aqueous medium, wherein the aqueous medium comprises at least 98 weight-%, more preferably at least 99 weight-% more preferably at least 99.5 weight-% more preferably 100 weight-%, water, based on the total weight of the aqueous medium being 100 weight-%.

12. A process for protecting a surface of a substrate, the process comprising(I) applying a mixture comprising nanocellulose and a solvent to a surface of a substrate (to be protected); thereby obtaining a film comprising solvent and nanocellulose on at least a part of the surface of the substrate;(II) removing solvent from the film comprising nanocellulose obtained in step (I) (drying), and optionally curing of binder, thereby obtaining at least one layer of nanocellulose on at least a part of the surface of the substrate; wherein the removal of solvent and optionally curing of binder according to step (II) is preferably done by a method selected from the group consisting of infrared heating, microwave heating, conductive heating and mixed forms of two or more of these methods;240826W001- 40 - the process further comprising(iii) applying an aqueous medium to the at least one layer of nanocellulose on at least a part of the surface of the substrate obtained in (ii), thereby obtaining an aqueous film comprising nanocellulose on at least a part of the surface of the substrate;(iv) removing the aqueous film comprising nanocellulose obtained in (iii) from the surface of the substrate, thereby obtaining a washed-off aqueous mixture comprising nanocellulose and a substrate, the surface thereof being substantially free of nanocellulose.

13. The process of claim 12, wherein the substrate is made of glass and / or metal and has a primary coating on at least one surface, wherein in (I) the mixture comprising nanocellulose and a solvent is applied to the surface of the substrate (to be protected) on top of the primary coating, wherein the primary coating preferably comprises or is a coating selected from the group consisting of low emissivity coating, protective coating, reflective coating, sun protection coating, anti-reflective coating, self-cleaning coating, and mixtures of two or more of these coatings.

14. The process of claim 12 or 13, wherein the nanocellulose provided according to (I) is obtained or obtainable from cellulose fibers, preferably obtained or obtainable by from a polymeric material comprising cellulose fibers.

15. An aqueous mixture comprising nanocellulose, preferably obtainable or obtained by the process of any one of claims 12 to 14, the aqueous mixture further comprising at least one binder or a reaction product of at least one binder and / or at least one filler; or an aqueous mixture comprising nanocellulose, preferably obtainable or obtained by the process of any one of claims 12 to 14, the aqueous mixture essentially comprising neither a binder nor a reaction product of a binder and / or a filler, wherein preferably less than 1 weight-%, more preferably less than 100 weight-ppm, more preferably less than 10 weight-ppm are binder or a reaction product of a binder and / or a filler, based on the total weight of the aqueous mixture being 100 weight-%.

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