Biodegradable and reusable non-toxic coating composition

Abstract

The present invention relates to a coating composition for a substrate, comprising a microcrystalline cellulose composition, at least one silane, at least one acid catalyst, a liquid dispersion phase, and optionally at least one inorganic filler. The present invention also relates to the use of this composition for a release coating of a substrate such as a paper surface or a metal surface. Finally, the present invention relates to an article having at least one surface coated with a coating composition according to the present invention.

Description

Technical Field

[0001] Field of the Invention The present invention relates to the general technical field of sol-gel type coatings. More specifically, the present invention relates to the field of environmentally friendly, non-toxic and durable coatings. In certain embodiments, the coatings of the present invention may exhibit peel characteristics, water repellent and / or oil repellent characteristics with respect to pressure sensitive adhesive compositions.

Background Art

[0002] Release liners are an important component of the release surface that reversibly adheres to the adhesive layer. Examples of such surfaces are present on the non-adhesive (outer) surfaces of food disposable accessories such as adhesive tapes, holders for stamps or labels, and paper cups for cakes.

[0003] In the field of pressure sensitive adhesives, it is often desirable to prepare adhesive products, such as labels and tapes, and to store the products prior to their use. During storage, it is convenient to attach the product carrying the adhesive to an intermediate surface from which it needs to be peeled off prior to use. For example, an adhesive tape is wound on a reel such that the adhesive surface for one turn of the tape is adhered to the non-adhesive surface of the tape in the previous turn. To unwind the tape prior to its use, it is necessary to peel the upper tape with the adhesive from the inner tape, usually. In another example, labels carrying an adhesive often carry a backing paper with a release surface from which they can be easily peeled off prior to their intended use.

[0004] This protective paper or release liner typically has a plastic film or glassine paper. Usually, the release liner is coated on one or both sides with a very thin layer of silicone or fluorocarbon polymer and serves as a backing to protect the adhesive surface when the tape is wound or to protect it when a label or stamp is reversibly attached to its support. When a force is applied, the release surface of the liner enables the wound tape, label, or stamp to be peeled from its release surface without adversely affecting the adhesive properties of the tape, label, or stamp.

[0005] To provide a liner, such as a paper support, with release properties, current coatings are based on several types of polymers used as release coatings, such as silicone networks, silicone-containing copolymers, polymers having long-chain alkyl or fluoroalkyl side chains, fluoropolymers, and polyolefins. These polymers have a surface energy lower than that of commonly used pressure-sensitive adhesive (PSA) compositions, which is an important property of PSA materials.

[0006] For forming one or more release coating surfaces The use of sol-gel compositions is known in the art. However, these coating compositions have drawbacks in terms of performance regarding durability and release properties.

[0007] To overcome these drawbacks, release compositions further comprising a silicone oil-type lubricant have been proposed to improve their release properties. However, these silicone oils have limited heat resistance, and it is always observed that the release properties of the coating deteriorate with use.

[0008] Furthermore, the aforementioned silicone oil-containing coating composition according to the prior art is used in the form of an emulsion bath (or coating bath) for coating a film support, which is then cross-linked under thermal activation and / or under radiation (UV, electron beam) to form a water-repellent and peelable coating, which hinders the ease of implementation of the surface coating.

[0009] To improve their non-adhesive performance, it is also known to add fluorinated silanes or composite synthetic polymers to sol-gel type coatings. However, the use of fluorinated compounds can be harmful to humans and the environment. This is because of the presence of fluorinated compounds and high molecular weight synthetic polymers that prevent the biodegradation and recycling of materials coated with compositions containing fluorinated silanes and / or composite synthetic polymers.

[0010] Therefore, such solutions are not sustainable. The reason is that they involve the use of chemical compounds that limit the recyclability and / or biodegradability of PSA non-adhesive coatings.

[0011] Therefore, there remains a need to provide a release coating composition for PSA adhesives, particularly one that enables overcoming the aforementioned drawbacks, for example, a release coating composition for surfaces such as the surface of accessories for food or beverages. Furthermore, considering the usefulness of such coatings in food or beverage utensils, there is also a need to provide a safe coating that imparts a barrier property to water and oil to the coated substrate.

[0012] The use of the coating composition described below enables a simple coating that can provide coated articles that are not harmful to human health or the environment. Advantageously, this coating has barrier properties against the diffusion of water and / or oils and fats, and is suitable for coating substrates that come into contact with water or oily substances, such as food and beverage containers. In a further advantageous aspect, the coating composition according to the invention exhibits reversible adhesiveness that is non-adhesive under normal forces applied by the user, for example forces on the order of 1 to 500 g / cm, for opening disposable food containers or peeling stamps from backing sheets. More advantageously, the reversibility of the non-adhesive nature of the composition persists over a long period of time, regardless of temperature or humidity. In addition, the composition according to the invention does not diffuse into the substrate onto which it is applied or into the adhesive layer with which it comes into contact.

Summary of the Invention

[0013] The present invention relates to a coating composition comprising: - a cellulose composition in an amount in the range of 0.1% to 15% by weight, based on the total weight of the coating composition, wherein the cellulose is selected from microcrystalline cellulose, microfibrillated cellulose, and mixtures thereof, - at least one silane in an amount in the range of 50% to 80% by weight, based on the total weight of the coating composition, - at least one acid catalyst in an amount in the range of 0.05% to 5.0% by weight, based on the total weight of the composition, - optionally at least one inorganic extender, and - a liquid dispersion phase in an amount sufficient to reach 100% of the total weight of the coating composition.

[0014] At least one silane can be selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof. Preferably, at least one silane is selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, and even more preferably, at least one silane is methyltriethoxysilane.

[0015] When the coating composition further contains at least one inorganic filler (or extender), it can be selected from silicon dioxide, calcium carbonate, magnesium carbonate, aluminum oxide, layered silicate, inosilicate, tectosilicate, talc, zinc sulfate, magnesium oxide, zinc flakes, kaolin, albite, dolomite, cerium oxide, sodium aluminate, calcium sulfate, barium sulfate, zinc stearate and mixtures thereof. Preferably, at least one inorganic filler is selected from silicon dioxide, calcium carbonate and mixtures thereof, and even more preferably, at least one inorganic filler is silicon dioxide, especially micronized silicon dioxide.

[0016] At least one acid catalyst can be selected from preferably a monobasic acid further selected from hydrochloric acid, nitric acid, acetic acid; and preferably a polybasic acid further selected from carbonic acid, sulfuric acid, citric acid, and mixtures thereof. Even more preferably, the acid catalyst is hydrochloric acid.

[0017] In some embodiments, the coating composition comprises a cellulose composition that is a microcrystalline cellulose composition having crystals with an average diameter in the range of 30 - 200 μm, and the average diameter is determined by a sieving method.

[0018] In some embodiments, the dispersed phase is an aqueous phase or a hydroalcoholic phase, and preferably the dispersed phase is 100% water.

[0019] In some embodiments, the coating composition comprises the following: - Preferably, a microcrystalline cellulose composition in an amount in the range of 1 wt% to 15 wt%, preferably 1 wt% to 5 wt%, based on the total weight of the composition, and even more preferably a microcrystalline cellulose composition having crystals with an average diameter in the range of 30 to 200 μm, as determined by a sieving method; - At least one silane in an amount in the range of 60 wt% to 80 wt% based on the total weight of the composition, more preferably at least one silane selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, and even more preferably at least one silane which is methyltriethoxysilane; - At least one acid catalyst in an amount in the range of 1.0 wt% to 5.0 wt% based on the total weight of the composition; - Optionally, at least one inorganic filler in an amount in the range of 0.1 wt% to 10 wt% based on the total weight of the composition, and even more preferably at least one inorganic filler selected from silicon dioxide, calcium carbonate and mixtures thereof; - A liquid dispersion phase in an amount sufficient to reach 100% of the total weight of the composition.

[0020] In some embodiments, the coating composition comprises the following: - Preferably, a microfibrillated cellulose composition in an amount in the range of 1 wt% to 15 wt%, preferably 1 to 5 wt%, based on the total weight of the composition; - At least one silane in an amount in the range of 60 wt% to 80 wt% based on the total weight of the composition, more preferably at least one silane selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, and even more preferably at least one silane which is methyltriethoxysilane; - At least one acid catalyst in an amount in the range of 1.0 wt% to 5.0 wt% based on the total weight of the composition; - Preferably, at least one inorganic filler in an amount in the range of 0.1% to 10% by weight based on the total weight of the composition, more preferably at least one inorganic filler selected from silicon dioxide, calcium carbonate, and mixtures thereof; - A liquid dispersion phase that is preferably 100% water in an amount sufficient to reach 100% of the total weight of the composition.

[0021] The present invention further relates to the use of the coating composition described herein, wherein the substrate is a cellulose-containing substrate, or the substrate is a plastic or metal substrate, preferably the substrate is a cellulose-containing substrate containing at least 70% by weight of cellulose based on the total weight of the substrate.

[0022] In some embodiments, the coating is a release coating, preferably a release coating configured to reversibly adhere to an adhesive surface, such as a layer containing, for example, acrylate and / or polyacrylate.

[0023] Alternatively or additionally, the coating is a water-repellent and / or oil-repellent coating for a cellulose-containing substrate.

[0024] The present invention also relates to a composite article comprising a substrate, wherein the substrate is at least partially coated with the coating composition described herein.

[0025] Typically, the substrate of the composite article contains at least 70% by weight of cellulose based on the total weight of the substrate.

[0026] Alternatively, the substrate comprises or is made from metal or plastic.

[0027] In some embodiments, the composite article is selected from food, preferably disposable food, food protection paper, cardboard containers for food, disposable tableware, paper trays, paper cups, adhesive tapes, supports for stamps or labels, molds for food cooking, especially molds for cakes or injection molds.

[0028] Definition In the present invention, the following terms have the following meanings: "Anti-adhesive coating" or "release coating" refers to a coating that can adhere (fix) reversibly to an adhesive layer. Reversible adhesion is reversible when a separating (or peeling) force exceeding a threshold value of 1 g / cm or more, 5 g / cm or more, preferably 10 g / cm or more, and more preferably 12 or 15 g / cm or more is applied to a release liner, meaning the adhesion of a certain adhesive layer, particularly a pressure-sensitive adhesive (PSA) layer, and at the same time the adhesive layer maintains its adhesive properties even after its separation from the release coating.

Mode for Carrying Out the Invention

[0029] In a first aspect, the present invention relates to a composition, which composition comprises a microcrystalline cellulose composition, at least one silane, at least one acid catalyst, and a liquid dispersion phase.

[0030] In particular, the coating composition of the present invention comprises the following: - A cellulose composition in an amount in the range of 0.1 wt% to 15 wt%, preferably 1 wt% to 15 wt%, more preferably 1 wt% to 5 wt% based on the total weight of the coating composition, wherein the cellulose is selected from microcrystalline cellulose, microfibrillated cellulose, and mixtures thereof; - At least one silane in an amount in the range of 50 wt% to 80 wt% based on the total weight of the coating composition; - At least one acid catalyst in an amount in the range of 0.05 wt% to 5.0 wt% based on the total weight of the composition; - Optionally at least one inorganic extender; and - A liquid dispersion phase in an amount sufficient to reach 100% of the total weight of the coating composition.

[0031] The composition according to the present invention comprises at least one silane in an amount in the range of 50 wt% to 80 wt%, preferably 60 wt% to 80 wt%, even more preferably 60 wt% to 70 wt% based on the total weight of the composition.

[0032] In one embodiment, at least one silane is selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof, preferably at least one silane is selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, and mixtures thereof, more preferably at least one silane is methyltriethoxysilane.

[0033] In some embodiments, the composition further comprises at least one inorganic extender.

[0034] When the composition according to the present invention comprises at least one inorganic extender, it may be in an amount in the range of 0.05 wt% to 20 wt%, preferably 0.1 wt% to 10 wt%, more preferably 1 wt% to 5 wt%, based on the total weight of the composition.

[0035] The inorganic extender may be selected from silicon dioxide, calcium carbonate, magnesium carbonate, aluminum oxide, phyllosilicate, inosilicate, tectosilicate, talc, zinc sulfate, magnesium oxide, zinc flakes, kaolin, albite, dolomite, cerium oxide, sodium aluminate, calcium sulfate, barium sulfate, zinc stearate, and mixtures thereof, preferably at least one inorganic extender is selected from silicon dioxide, calcium carbonate, and mixtures thereof, more preferably at least one inorganic extender is micronized silicon dioxide.

[0036] In a preferred embodiment, the inorganic extender is preferably silicon dioxide in micronized form. Micronized silicon dioxide typically comprises silicon dioxide particles having an average diameter of 2 - 5 μm, typically 2 - 3 μm, characterized by a sieving method.

[0037] At least one acid catalyst is present in an amount sufficient to enable the polymerization or vitrification of at least one silane when the composition is applied to a substrate. The composition according to the invention contains, in relation to the total weight of the composition, an amount of at least one acid catalyst in the range from 0.01% to 5% by weight, preferably from 0.05% to 5% by weight, even more preferably from 0.2% to 1% by weight.

[0038] The at least one acid catalyst can be selected from monobasic acids, polybasic acids, and mixtures thereof. Preferably, the monobasic acid is selected from carbonic acid, sulfuric acid, citric acid, and mixtures thereof. In one embodiment, the monobasic acid is selected from hydrochloric acid, nitric acid, and acetic acid. In a preferred embodiment, the acid catalyst is hydrochloric acid. Thus, in some embodiments, the at least one acid catalyst is hydrochloric acid in an amount in the range from 0.01% to 5% by weight, preferably from 0.05% to 5% by weight, more preferably from 0.2% to 1% by weight, based on the total weight of the composition.

[0039] The composition according to the invention contains, in relation to the total weight of the composition, an amount of cellulose composition in the range from 0.1% to 15% by weight, preferably from 1% to 15% by weight or from 0.5% to 10% by weight, even more preferably from 1% to 5% by weight. The cellulose composition is selected from microcrystalline cellulose compositions, microfibrillated cellulose compositions, and mixtures thereof.

[0040] In some embodiments, the cellulose composition is a microcrystalline cellulose composition. Microcrystalline cellulose (MCC) is a natural polymer composed of glucose units linked by 1-4β glycosidic bonds. Typically, the microcrystalline cellulose composition has crystals with an average diameter in the range of 30 to 200 μm, and the average diameter is determined by the sieve method. In one embodiment, the microcrystalline cellulose composition has crystals with an average diameter in the range of 5 to 200 μm, preferably 30 to 200 μm, and even more preferably 60 to 150 μm, and the average diameter is determined by the sieve method. In one embodiment, the microcrystalline cellulose composition has crystals with an average diameter in the range of 60 to 100 μm. In some embodiments, the coating composition of the present invention contains an MCC composition in an amount in the range of 0.1 wt% to 15 wt%, preferably 1 wt% to 15 wt% or 0.5 wt% to 10 wt%, and even more preferably 1 wt% to 5 wt% based on the total weight of the coating composition.

[0041] In some embodiments, the cellulose composition is a microfibrillated cellulose (MFC) composition. Microfibrillated cellulose is a cellulose-based product and is described, for example, in U.S. Patent Application Publication No. 4,374,702. Microfibrillated cellulose has at least one reduced length scale (diameter, fiber length) compared to non-fibrillated cellulose. In the (non-fibrillated) cellulose that is the starting product for producing microfibrillated cellulose, there are no individual "separated" cellulose "fibrils", or at least not in a significant or appreciable amount. The cellulose in the fiber is an aggregate of fibrils. Typical cellulose fibrils aggregate into microfibrils, which in turn aggregate into larger fibril bundles and ultimately into cellulose fibers. The diameter of cellulose fibers is usually in the range of 10 to 50 μm (the length of these fibers is even longer). When cellulose fibers are microfibrillated, a heterogeneous mixture of "released" fibrils with cross-sectional dimensions and lengths on the nm to μm scale can result. Fibrils and bundles of fibrils can coexist in the resulting microfibrillated cellulose.

[0042] In an exemplary embodiment of the present invention, the microfibrillated cellulose has at least one length scale, i.e., the diameter and / or length of the fibrils, that is reduced relative to the diameter and / or length of the fibers of non-fibrillated cellulose, and preferably the diameter of the microfibrillated cellulose fibrils that make up the microfibrillated cellulose of the present invention is in the nanometer range, i.e., 1 nm to 1000 nm, preferably on average in the range of 10 nm to 500 nm. Individual fibrils or bundles of fibrils can be identified and readily determined by any means well known in the art, for example, by conventional optical microscopy at a magnification of 40 times.

[0043] In some embodiments, the coating composition of the present invention comprises an MFC composition in an amount in the range of 0.1 wt% to 15 wt%, preferably 1 wt% to 15 wt% or 0.5 wt% to 10 wt%, more preferably 1 wt% to 5 wt%, based on the total weight of the coating composition.

[0044] The foregoing components can be dispersed in any dispersion phase known in the art. In one embodiment, the dispersion phase is an aqueous phase or a hydroalcoholic phase. In one embodiment, the hydroalcoholic phase consists of water in an amount of at least 5 wt%, at least 10 wt%, at least 20 wt% or at least 30 wt%, based on the total weight of the hydroalcoholic phase, and at least one short-chain alcohol, i.e., a C1-C4 chain alcohol. For example, the at least one short-chain alcohol is selected from ethanol, methanol, isopropanol, butanol and mixtures thereof.

[0045] The dispersion phase is typically an amount sufficient to disperse the components of the composition. In a variant, the dispersion phase is an amount sufficient to reach 100% of the total weight of the coating composition (QSP). Usually, the dispersion phase is in an amount in the range of 15 wt% to 40 wt% based on the total weight of the composition. In a variant, the components of the composition, such as microcrystalline cellulose and / or inorganic extender, are in the form of a suspension in their dispersion phase, in which case the dispersion phase of the components constitutes the dispersion phase of the composition according to the invention.

[0046] In a preferred embodiment, the dispersion phase is 100% water.

[0047] In some embodiments, the coating composition comprises: - a cellulose composition in an amount preferably in the range of 1 wt% to 15 wt%, more preferably 1 wt% to 5 wt%, wherein the cellulose is selected from microcrystalline cellulose, microfibrillated cellulose and mixtures thereof; - Preferably in an amount in the range of 50% to 80% by weight, more preferably 60% to 80% by weight, even more preferably 60% to 70% by weight of at least one of the above-mentioned silanes; - In an amount sufficient for the polymerization of at least one silane, preferably in the range of 0.01% to 5% by weight, more preferably 0.05% to 5.0% by weight, even more preferably 0.2% to 1% by weight of at least one of the above-mentioned acid catalysts; and - An amount sufficient to reach 100% of the total weight of the composition, typically in the range of 15% to 40% by weight of the liquid dispersion phase. The percentages are expressed by weight relative to the total weight of the composition.

[0048] In some embodiments, the coating composition comprises: - In an amount preferably in the range of 1% to 15% by weight, more preferably in the range of 1% to 5% by weight, of a cellulose composition selected from MCC, MFC or combinations thereof; - Preferably in an amount in the range of 50% to 80% by weight, more preferably 60% to 80% by weight, even more preferably 60% to 70% by weight, preferably at least one of the above-mentioned silanes selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, even more preferably at least one of the above-mentioned silanes which is methyltriethoxysilane; - In an amount sufficient for the polymerization of at least one silane, preferably in the range of 0.01% to 5% by weight, preferably 0.05% to 5.0% by weight, more preferably 0.2% to 1% by weight of at least one acid catalyst, preferably hydrochloric acid; and - An amount sufficient to reach 100% of the total weight of the composition, typically in the range of 15% to 40% by weight of the liquid dispersion phase. The percentages are expressed by weight relative to the total weight of the composition.

[0049] In some embodiments, the coating composition comprises: - A composition of microcrystalline cellulose in an amount preferably in the range of 1 wt% to 15 wt%, more preferably in the range of 1 wt% to 5 wt%; even more preferably, a composition of microcrystalline cellulose having crystals with an average diameter in the range of 5 to 200 μm, 30 to 200 μm, 60 μm to 200 μm, preferably 60 μm to 150 μm, more preferably 60 μm to 100 μm, as measured by the sieving method. - At least one of the above-mentioned silanes in an amount preferably in the range of 50 wt% to 80 wt%, preferably in the range of 60 wt% to 80 wt%, even more preferably in the range of 60 wt% to 70 wt%; preferably at least one of the above-mentioned silanes selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, even more preferably at least one of the above-mentioned silanes which is methyltriethoxysilane. - At least one acid catalyst, preferably hydrochloric acid, in an amount sufficient for the polymerization of at least one silane, preferably in the range of 0.01 wt% to 5 wt%, preferably in the range of 0.05 wt% to 5.0 wt%, more preferably in the range of 0.2 wt% to 1 wt%; and - A liquid dispersion phase in an amount typically in the range of 15 wt% to 40 wt%, in an amount sufficient to reach 100% of the total weight of the composition. The percentages are expressed by weight relative to the total weight of the composition.

[0050] In some embodiments, the coating composition comprises: - A composition of microcrystalline cellulose in an amount preferably in the range of 1 wt% to 15 wt%, more preferably in the range of 1 wt% to 5 wt%; even more preferably, a composition of microcrystalline cellulose having crystals with an average diameter in the range of 5 to 200 μm, 30 to 200 μm, 60 μm to 200 μm, preferably 60 μm to 150 μm, more preferably 60 μm to 100 μm, as measured by the sieving method. - Preferably in an amount in the range of 50% to 80% by weight, more preferably in the range of 60% to 80% by weight, even more preferably in the range of 60% to 70% by weight, of at least one of the above-mentioned silanes; preferably at least one of the above-mentioned silanes selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, even more preferably at least one of the above-mentioned silanes which is methyltriethoxysilane; - Preferably in an amount in the range of 0.01% to 5% by weight, more preferably in the range of 0.05% to 5.0% by weight, even more preferably in the range of 0.2% to 1% by weight, of at least one acid catalyst in an amount sufficient for the polymerization of at least one silane, preferably hydrochloric acid; - Preferably in an amount in the range of 1% to 5% by weight based on the total weight of the composition, even more preferably at least one inorganic extender which is silicon dioxide, particularly micronized silicon dioxide; and - Preferably in an amount in the range of 15% to 40% by weight of a liquid dispersion phase, even more preferably a liquid dispersion phase which is 100% water. The percentages are expressed by weight relative to the total weight of the composition.

[0051] In some embodiments, the coating composition comprises: - Preferably in an amount in the range of 1% to 5% by weight based on the total weight of the composition, even more preferably a microcrystalline cellulose composition having crystals with an average diameter in the range of 60 to 150 μm as determined by the sieve method; - Preferably in an amount in the range of 60% to 70% by weight of at least one silane, at least one silane selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, preferably at least one silane which is methyltriethoxysilane; - Preferably in an amount in the range of 0.2% to 1.0% by weight based on the total weight of the composition, of at least one acid catalyst, preferably hydrochloric acid; - At least one inorganic extender selected from at least one inorganic extender, calcium carbonate, silicon, particularly micronized silicon dioxide, and mixtures thereof, in an amount in the range of 1% to 5% by weight based on the total weight of the composition, more preferably silicon dioxide, particularly micronized silicon dioxide; and - A liquid dispersion phase in an amount in the range of 15% to 40% by weight, an amount sufficient to reach 100% of the total weight of the composition, more preferably a liquid dispersion phase of 100% water. The percentages are expressed by weight relative to the total weight of the composition.

[0052] In some embodiments, the coating composition comprises the following: - A cellulose composition selected from an MCC composition or an MFC composition, preferably in an amount in the range of 1% to 5% by weight based on the total weight of the composition; - At least one silane selected from at least one silane, methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, and mixtures thereof, preferably in an amount in the range of 60% to 70% by weight, more preferably at least one silane which is methyltriethoxysilane; - At least one acid catalyst, preferably hydrochloric acid, in an amount in the range of 0.2% to 1.0% by weight based on the total weight of the composition; - At least one inorganic extender selected from at least one inorganic extender, calcium carbonate, silicon, particularly micronized silicon dioxide, and mixtures thereof, preferably in an amount in the range of 1% to 5% by weight based on the total weight of the composition, more preferably silicon dioxide, particularly micronized silicon dioxide; and - A liquid dispersion phase in an amount in the range of 15% to 40% by weight, an amount sufficient to reach 100% of the total weight of the composition, even more preferably a liquid dispersion phase of 100% water. The percentages are expressed by weight relative to the total weight of the composition.

[0053] In some embodiments, the coating composition comprises the following: - Preferably, a microcrystalline cellulose composition in an amount in the range of 1 wt% to 5 wt% based on the total weight of the composition, and more preferably, a microcrystalline cellulose composition having crystals with an average diameter in the range of 60 to 150 μm as determined by the sieve method; - At least one silane selected from at least one silane, methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, and mixtures thereof, preferably at least one silane in an amount in the range of 60 wt% to 70 wt% based on the total weight of the composition, preferably methyltriethoxysilane; - At least one acid catalyst, preferably hydrochloric acid, in an amount in the range of 0.2 wt% to 1.0 wt% based on the total weight of the composition; - At least one inorganic extender selected from at least one inorganic extender, calcium carbonate, silicon, particularly micronized silicon dioxide, and mixtures thereof, preferably at least one inorganic extender in an amount in the range of 1 wt% to 5 wt% based on the total weight of the composition, more preferably silicon dioxide, particularly micronized silicon dioxide; and - A liquid dispersion phase in an amount in the range of 15 wt% to 40 wt%, an amount sufficient to reach 100% of the total weight of the composition, and even more preferably a liquid dispersion phase of 100% water. The percentages are expressed by weight relative to the total weight of the composition.

[0054] In some embodiments, the coating composition comprises the following: - Preferably, an MFC composition in an amount in the range of 1 wt% to 5 wt% based on the total weight of the composition; - At least one silane selected from at least one silane, methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, and mixtures thereof, preferably at least one silane in an amount in the range of 60 wt% to 70 wt% based on the total weight of the composition, preferably methyltriethoxysilane; - At least one acid catalyst, preferably hydrochloric acid, in an amount in the range of 0.2 wt% to 1.0 wt% based on the total weight of the composition; at least one inorganic filler, preferably in an amount ranging from 1% to 5% by weight relative to the total weight of the composition, selected from calcium carbonate, silicon, in particular micronized silicon dioxide, and mixtures thereof, more preferably silicon dioxide, in particular micronized silicon dioxide; and A liquid dispersed phase in an amount ranging from 15% to 40% by weight, in an amount sufficient to reach 100% of the total weight of the composition, more preferably 100% water. The percentages are expressed by weight relative to the total weight of the composition.

[0055] The coating compositions of the present invention are suitable for providing release coatings on substrates such as cellulose-containing substrates, metal substrates, plastic substrates, etc., as described above. Furthermore, the coating compositions of the present invention are suitable for providing release water and / or oil barrier (oil repellent) coatings on substrates such as cellulose-containing substrates, metal substrates, plastic substrates, etc., preferably on cellulose-containing substrates.

[0056] Therefore, in a second aspect, the present invention relates to the use of a coating composition according to any of the preceding embodiments for coating a substrate.

[0057] In some embodiments, the coating is a release coating, a water repellent (or waterproof) coating and / or an oil repellent (or oil barrier or grease barrier) coating, preferably the coating is a release coating.

[0058] Alternatively, the present invention relates to a method for preparing a release coating, a water-repellent coating and / or an oil-repellent coating, preferably a release coating, the method comprising contacting a substrate with a composition according to any one of the above-mentioned embodiments.

[0059] In some embodiments, the use or coating method according to the present invention relates to a release coating, particularly a release coating that can adhere to an adhesive layer in a reversible manner as defined above. In some other embodiments, the use or coating method according to the present invention relates to a coating against the diffusion of water or oil (fatty or greasy) substances, particularly a coating of a cellulose substrate of an article intended for food and / or beverage applications or articles.

[0060] In certain embodiments, the substrate is a cellulose substrate, a metal substrate, or a plastic substrate, preferably the substrate is a cellulose substrate. A cellulose substrate or a cellulose-containing substrate means a substrate in which at least 70% by weight of the total weight of the substrate contains cellulose. The cellulose-containing substrate may be selected from paper, treated paper, glassine paper, cardboard, cellulose support, low-porosity cellulose support, and wood, and preferably may be selected from paper, glassine paper, and cardboard.

[0061] In some embodiments, the method of coating a substrate includes the following steps: a) providing a substrate, b) providing a coating composition according to the present invention, and then c) applying the coating composition at least in part, preferably to at least the surface of the substrate to obtain a preliminary composite article, and then d) drying the preliminary composite article at a temperature in the range of 30°C to 280°C to obtain a coated substrate.

[0062] In some embodiments, the method includes the following steps: a) providing a substrate selected from a cellulose-containing substrate, metal, or plastic substrate, b) preparing a coating composition according to any one of the above embodiments, c) applying the coating composition to at least one surface of the substrate to obtain a preliminary composite coated article, and d) drying the preliminary composite coated article at a temperature in the range of 20 °C to less than 280 °C for several days to obtain a composite coated article.

[0063] In a third aspect, the invention relates to a composite article comprising a substrate, said substrate being at least partially coated with a coating composition according to the invention. Advantageously, the coating composition according to the invention can reversibly adhere to the surface of a pressure-sensitive adhesive layer, such as an adhesive surface, in particular an adhesive layer present in Loctite® 592, Technomelt® PS, Extra Strong Premium Carpet Tape NIU 4202® sold by Scotch, which contains acrylates and / or polyacrylates.

[0064] In certain embodiments, the composite article comprises a cellulose, plastic, or metal substrate body as defined above.

[0065] In some embodiments, the substrate comprises at least 70% by weight cellulose, based on the total weight of the substrate. In some embodiments, the substrate body is substantially composed of or made from metal or plastic.

[0066] In some embodiments, the coated article is selected from food, preferably disposable food, food protection paper, cardboard containers for food, disposable tableware, paper trays, paper cups, adhesive tapes, supports for stamps or labels, molds for food cooking, in particular molds for cakes or injection molds.

[0067] In one embodiment, the article is selected from food, in particular disposable food, food protection paper, cardboard containers for food, disposable tableware, adhesive tapes, supports for stamps or labels, molds for food cooking, in particular molds for cakes or injection molds.

[0068] In a fourth aspect, the invention relates to a composite coated article comprising: - A first layer made of the above-mentioned substrate, typically selected from a cellulose-containing substrate, a metal, or a plastic substrate, preferably a cellulose-containing substrate. - At least a second layer containing the coating composition according to any one of the above embodiments.

[0069] In one embodiment, the composite-coated article is obtained or directly obtained by coating a substrate with the coating method of the present invention.

[0070] In one embodiment, the composite-coated article is a preliminary composite-coated article.

[0071] In one embodiment, the composite-coated article is a (dried) composite-coated article. It should be understood that the drying step (d) removes the dispersed phase of the coating composition. Thus, the composite-coated article includes: - A first layer made of the above-mentioned substrate, typically selected from a cellulose-containing substrate, a metal, or a plastic substrate, preferably a cellulose-containing substrate. - At least a second layer containing cellulose (MCC, MFC, or a combination thereof) in the above-mentioned at least one silane coating composition condensed by an acid catalyst.

[0072] Therefore, the composite-coated article of the present invention can exhibit the peeling characteristics as defined above and / or can hold all liquid parts (such as water, oil) inside or outside the package while avoiding any contamination or leakage.

[0073] Examples This invention is further illustrated by the following examples, which are non-limiting.

[0074] Example 1: Compositions according to the present invention Compositions A - G according to the present invention are prepared by mixing the components according to Table 1.

Table 1

[0075] The components of Composition A to G were mixed for 2 hours to 24 hours (ideally 6 hours to 18 hours). The viscosities of Composition A to G after mixing were less than 100 cps at 25°C.

[0076] The obtained coating composition (the "sol" composition) was then applied to a paper substrate to form a release layer.

[0077] The release coat was applied as a single layer on A4 using a bar coater in an amount of 1 ml to 4 ml of a UPM Prego® paper A4 sheet liner (55 gsm).

[0078] The paper thus coated was then dried in an oven at 150°C for 30 minutes.

[0079] Example 2: Release properties Materials and methods To quantitatively measure the release properties (anti-adhesion) of the composition according to Example 1, we used a dynamic mechanical analyzer from Seiko Instruments Inc.

[0080] Rectangular samples of 5 mm x 30 mm coated with each of the compositions A to G according to Example 1 were prepared and tested in tensile mode using a Seiko® DMS110 dynamic mechanical analyzer console according to the conditions detailed below.

[0081] The samples were: - cooled to -30°C and equilibrated at this temperature for 15 minutes (Condition 1), then - heated to 200°C at a rate of -2°C / min (Condition 2), then - cooled to room temperature (Condition 3).

[0082] Condition 4 consists of maintaining the sample at 38°C and 90% relative humidity for 24 hours.

[0083] This procedure was repeated a total of 4 times for each sample.

[0084] Results The results are shown in Table 2.

Table 2

[0085] Samples coated with Compositions A - G according to the present invention maintained the reversibility of the non - adhesive property regardless of temperature and humidity according to Conditions 1 - 4.

[0086] In addition, the peel characteristics of the coatings using Compositions A - G were empirically confirmed by reversibly adhering commercially available adhesives such as Avery® or 3M® brand adhesive labels, double - sided adhesive carpet tape, and other acrylic or polyacrylate - based stickers onto the samples coated with Compositions A - G.

[0087] Example 3: Oil and water repellency and peelability The oil and water repellency of the coating compositions according to the present invention was evaluated by comparing a comparative sol - gel coating, a sol - gel using MCC according to the present invention, and a sol - gel using MFC according to the present invention using the TAPPI Cobb 30 - minute standard test. The Cobb test based on the TAPPI 441 test method measures the amount of water absorbed by non - water - absorbing and non - retaining paper, paperboard, and cardboard within a specified time under standardized conditions. Further, we conducted tests on the peel characteristics using FINAT Test Method 3 with the standard adhesive 7475.

[0088] The following test conditions were evaluated: (i) A standard sol - gel coated in one layer with a dry weight of 8 gsm (ii) A sol - gel MCC coated in one layer with a dry weight of 6 gsm (iii) A sol - gel MFC coated in one layer with a dry weight of 5 gsm

[0089] (ii) was synthesized using Sigma Aldrich's MCC 80μm. In the case of the MFC sol-gel (iii), the MFC was an industrial grade named Borregaard's Exilva® P 01-V.

[0090] The results are shown in Table 3.

Table 3

[0091] The MCC-based sol-gel and the MFC-based sol-gel showed improved results in both the Cobb values of oil and water compared to the standard sol-gel, and showed almost equivalent results in the FINAT peel test with the standard adhesive 7475, where the standard sol-gel coating did not show peel characteristics. This further demonstrates the effectiveness and versatility of the coating composition of the present invention.

Claims

1. 1. A coating composition comprising: microcrystalline cellulose in an amount ranging from 1% to 15% by weight relative to the total weight of the coating composition; at least one silane in an amount ranging from 50% to 80% by weight relative to the total weight of the coating composition, the at least one silane is at least one silane selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof; at least one acid catalyst in an amount ranging from 0.05% to 5.0% by weight relative to the total weight of the composition; optionally at least one inorganic filler; and a liquid dispersed phase in an amount sufficient to reach 100% of the total weight of the coating composition, the liquid dispersed phase being an aqueous phase or an alcohol phase; Including, Coating composition.

2. 10. The coating composition of claim 1, wherein the at least one silane is selected from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, and mixtures thereof, and even more preferably the at least one silane is methyltriethoxysilane.

3. 3. The coating composition according to claim 1 or 2, wherein the at least one inorganic filler is selected from silicon dioxide, calcium carbonate, magnesium carbonate, aluminum oxide, layered silicates, inosilicates, tectosilicates, talc, zinc sulfate, magnesium oxide, zinc flakes, kaolin, albaline, dolomite, cerium oxide, sodium aluminate, calcium sulfate, barium sulfate, zinc stearate and mixtures thereof, preferably the at least one inorganic filler is selected from silicon dioxide, calcium carbonate and mixtures thereof, even more preferably the at least one inorganic filler is silicon dioxide, in particular micronized silicon dioxide.

4. 4. The coating composition of any one of claims 1 to 3, wherein the at least one acid catalyst is selected from monobasic acids, preferably further selected from hydrochloric acid, nitric acid, and acetic acid; and polybasic acids, preferably further selected from carbonic acid, sulfuric acid, and citric acid, and mixtures thereof, and even more preferably the acid catalyst is hydrochloric acid.

5. The coating composition of claim 1, wherein the dispersed phase is 100% water.

6. 6. The coating composition according to claim 1, wherein the microcrystalline cellulose composition has crystals having an average particle size of 30 to 200 μm, the average particle size being measured by a sieving method.

7. microcrystalline cellulose in an amount ranging from 1% to 15% by weight, preferably in an amount ranging from 1% to 5% by weight relative to the total weight of the composition, and even more preferably having crystals with an average diameter ranging from 30 to 200 μm, the average diameter being determined by sieving; at least one silane, preferably in an amount ranging from 60% to 80% by weight relative to the total weight of the composition, and even more preferably chosen from methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane and mixtures thereof, and even more preferably methyltriethoxysilane; at least one acid catalyst, preferably in an amount ranging from 1.0% to 5.0% by weight relative to the total weight of the composition; optionally at least one inorganic filler, preferably in an amount ranging from 0.1% to 10% by weight relative to the total weight of the composition, and even more preferably at least one inorganic filler chosen from silicon dioxide, calcium carbonate and mixtures thereof; a liquid dispersed phase, preferably 100% water in an amount sufficient to reach 100% of the total weight of the composition; A composition for release coating of a substrate according to any one of claims 1 to 6, comprising:

8. 8. Use of the coating composition according to any one of claims 1 to 7 for coating a substrate, wherein the substrate is a cellulose-containing substrate or the substrate is a plastic or metal substrate, preferably the substrate is a cellulose-containing substrate comprising at least 70 wt. % cellulose relative to the total weight of the substrate.

9. 9. The use according to claim 8, wherein the coating is a release coating, preferably a release coating adapted to reversibly adhere to an adhesive surface, such as a layer comprising acrylate and / or polyacrylate.

10. 10. Use according to claim 8 or 9, wherein the coating is a water- and / or oil-repellent coating of the substrate, preferably the cellulose-containing substrate.

11. A composite article comprising a substrate, said substrate being at least partially coated with the release coating composition for substrates according to any one of claims 1 to 7.

12. 12. The composite article of claim 11, wherein the substrate comprises at least 70% by weight of cellulose, based on the total weight of the substrate.

13. 12. The composite article of claim 11, wherein the substrate is made from metal or plastic.

14. 14. The composite article according to any one of claims 11 to 13, selected from food products, preferably disposable food products, food protection paper, cardboard containers for food products, disposable tableware, paper trays, paper cups, adhesive tapes, supports for stamps or labels, moulds for food preparation, in particular cake moulds or metal moulds for injection moulding.