Hydrophobic surface coating for materials

Abstract

The invention relates to processes for coating and modifying non-textile surfaces, comprising the process steps of applying particles based on metal oxides and / or metal hydroxides of groups IIA, IVB, VIIB, VIIIB, IB, IIB, IIIA and IVA to a non-textile surface, the particles having a size range from 1 nm to 10 µm, and, following the application of the metal oxide or metal hydroxide particles to the non-textile surface, performing coating with hydrophobizing agent based on fluorine-free carboxylic acids, phosphoric esters and / or phosphonic acids. The invention further relates to coatings produced with the process of the invention, and to coated substrates obtained.

Description

HYDROPHOBIC COATING FOR MATERIAL SURFACES FIELD OF THE INVENTION

[0001] The present invention relates to an innovative process for the hydrophobization of non-textile surfaces, preferably fiber-based materials such as paper, cardboard, carton, pulp, or wood, as well as materials based on ceramics, stone, metal, and plastics. Fiber-based materials such as paper, cardboard, carton, pulp, or wood are widely used and versatile materials in numerous applications, from the packaging industry to the construction industry. However, their sensitivity to moisture and water often limits their durability, application possibilities, and resistance to environmental influences. STATE OF THE ART

[0002] Conventional methods for hydrophobizing fiber-based materials such as paper, cardboard, paperboard, pulp, or wood involve the use of waxes and paraffins, resins, or (fluorinated) polymers. Waxes and paraffins must sometimes be applied in significant quantities to achieve a satisfactory water-repellent effect, while the use of synthetic resins or polymers contributes to the generation of microplastics in the environment. The potential for environmental hazards is further increased, particularly through the use of fluorine-containing compounds. Furthermore, the use of the agents described above seals the surface of the materials and alters their tactile and / or optical properties.

[0003] A relatively new possibility for hydrophobizing fiber-based materials is the application of nanoparticles. Patent WO2019102459A1 presents a hydrophobization method for paper in which tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride nanoparticles are applied to the surface to be treated using ultrasound.

[0004] In patent US2018030282A1, 21 nm titanium dioxide particles and fluorine-free polymers based on polyolefins and acrylic acids are used to hydrophobize pulp. The latter compounds form a water-repellent film on the pulp surface, which exhibits increased roughness due to the treatment with titanium dioxide particles. This allows water contact angles of over 150° to be achieved.

[0005] The patent US2015075407A1 mentions the use of chromium complexes, together with metal oxide particles of the metals Al, Si, Ti, Zr, Au, Ag, Ni or Fe (or mixtures thereof) of size 1 to 35 nm and metal carboxylates as well as lecithins as hydrophobic agents.

[0006] Patent US2015330025A1 describes a process for hydrophobizing paper and cardboard using silanized silicon dioxide particles. For this purpose, silicon dioxide nanoparticles are dispersed in an aqueous-alcoholic solution and hydrophobized with (fluorinated) silane compounds. The dispersion is then applied to the substrate, onto which the hydrophobized nanoparticles are deposited by evaporation of the solvent.

[0007] Patent CA2739903A1 describes the hydrophobization of paper materials, among others, by applying multiple layers. The first layer consists of hydrophobized metal oxide particles ranging in size from 1 pm to 100 pm and an organic polymer-based binder to increase surface roughness. As a second layer, hydrophobized metal oxide particles ranging in size from 1 nm to 25 pm are applied, using hydrophobizing agents based on (fluorinated) silanes.

[0008] In patent US2014342098A1, the surface to be treated is treated with a sol-gel consisting of organometallic compounds of the metals Si, Al, In, Sn, or Ti, after which the corresponding metal oxides or metal hydroxides are deposited on the surface. The treated surface is then brought into contact with (fluorinated) silane compounds dissolved in organic solvents to create the water-repellent effect.

[0009] What all of the patents mentioned have in common is that the coating methods rely on the use of synthetic, petroleum-based polymers, in the form of the particles themselves, the binders, or the hydrophobizing agents, thus representing potential sources for the generation of microplastics. Alternatively, the metal oxide particles used are hydrophobized using organosilicon compounds, which severely impairs the hydrophobization process due to the hydrolysis sensitivity of the latter compounds. Last but not least, silanes are unsuitable for the functionalization of metals such as Al, Ti, or Zr due to their moderate stability. The metal carboxylates used in patent US2015075407A1 are also unsuitable as hydrophobizing agents.

[0010] In patent EP2102406, surface-modified metal oxide particles are used to hydrophobize textiles, which are coated with a (fluorine-containing) Dispersing and binding agents are applied to the textile fibers. In addition to silanes, perfluorinated carboxylic acids are also described for the surface treatment of metal oxides.

[0011] Patent EP2553026, on the other hand, describes the post-treatment of metal oxide particles and / or metal hydroxide particles with organophosphorus compounds, but for use in cosmetic products based on titanium and in a size range of 5 to 100 nm.

[0012] The state of the art therefore presents a problem. The aim of the present invention is to overcome these challenges and provide an effective, non-toxic, and environmentally friendly method for hydrophobizing non-textile surfaces, preferably fiber-based materials such as paper, cardboard, paperboard, cellulose, or wood, which does not require the use of fluorinated substances or plastics, nor does it require additional dispersants or binders. Applying this method creates a hydrophobic layer that significantly reduces or prevents the penetration of moisture and water into the material structure. This increases resistance to moisture damage, extends service life, and expands application possibilities in various environments. BRIEF DESCRIPTION OF THE INVENTION

[0013] The above-mentioned disadvantages are eliminated according to the invention according to the appended claims.

[0014] In one embodiment, the invention provides a coating and modification process for non-textile surfaces, comprising the process steps (i) applying particles based on metal oxides and / or metal hydroxides of groups HA, IVB, VIIB, VIIIB, IB, HB, IIIA and IVA to a non-textile surface, and, after applying the metal oxide or metal hydroxide particles to the non-textile surface, (ii) coating with hydrophobizing agents based on fluorine-free carboxylic acids, phosphoric acid esters and / or phosphonic acids. According to the invention, the particles are present in a size range from 1 nm to 10 pm, preferably in a size range from 30 to 700 nm. The application of the particles based on metal oxides and / or metal hydroxides can be carried out such that the surface concentration on the non-textile surface is in the range from 20 to 10,000 mg / m 2 for example in the range of 100 to 2,000 mg / m 2for example in the range of 200 to 1,000 mg / m 2 , or from 250 to 750 mg / m 2 .

[0015] In a preferred embodiment, the carboxylic acids, phosphoric acid esters, and / or phosphonic acids of the hydrophobizing agent are in the general form RCOOH, OP(OH)2OR, or OP(OH)2R, respectively, where R represents a hydrophobic radical in the form of aliphatic, branched or unbranched, alicyclic, or aromatic hydrocarbon groups having 5 to 40 carbon atoms, preferably 8 to 24 carbon atoms, and in particular 18 carbon atoms. In a further embodiment of the invention, R may contain polymerizable and / or functional groups.

[0016] The method is generally applicable to non-textile surfaces, for example, to substrates made of paper, cardboard, paperboard, pulp, wood, and other fiber-based materials, as well as to substrates based on ceramic, stone, metal, or plastic. In a preferred embodiment, the method is applied to paper, cardboard, paperboard, pulp, wood, and other fiber-based materials.

[0017] According to one embodiment of the invention, the metal oxides and / or meta II hydroxides are based on metals of groups HA, IVB, VII B, VI II B, IB, HB, IIIA and IVA, preferably the metals AI, Sn, Mg, Ca, Zn, Fe, Ti and in particular the metals AI, Mg, Ca, Ti and Zn.

[0018] In a further embodiment of the invention, the method comprises the use of a binder material for improved particle fixation. The binder material can be selected from epoxy derivatives, (homo- or copolymerized) (poly)carboxylic acids (such as citric acid, maleic acid, adipic acid, or polyacrylic acid) or corresponding derivatives such as carboxylic acid chlorides; (homo- or copolymerized) silanes or siloxanes; biopolymers based on proteins (e.g., gelatin, soy protein, casein), polysaccharides (e.g., starch, cellulose, chitosan), lipids (e.g., polyhydroxyalkanoates, polyglycolides), cutins, or suberins; as well as homo- or go-polymers of natural or synthetic origin (e.g. polyesters, polyethylenes, polypropylenes, polyethylene terephthalates, polystyrenes, polyvinyl chlorides, polyvinyl alcohols, polyvinyl acetates, polyurethanes, polyvinylpyrrolidone, polyacrylates and polymethacrylates, latexes, epoxy resins), or mixtures thereof.For example, the binder material can be applied to the substrate before the particles are applied to facilitate the bonding of the particles to the substrate surface. Preferably, the binder material is selected from citric acid, acrylic acid, or mixtures thereof.

[0019] Also part of the present invention are coatings for non-textile surfaces, comprising particles based on metal oxides and / or metal hydroxides of groups HA, IVB, VIIB, VIIIB, IB, HB, IIIA and IVA and a hydrophobizing agent based on fluorine-free carboxylic acids, phosphoric esters and / or phosphonic acids, wherein the particles are present in a size range from 1 nm to 10 pm, preferably in a size range from 30 to 700 nm. The carboxylic acids, phosphoric esters and / or phosphonic acids can be in the general form RCOOH, OP(OH)2OR or OP(OH)2R, where R represents a hydrophobic radical in the form of aliphatic, branched or unbranched, alicyclic or aromatic hydrocarbon groups having 5 to 40 carbon atoms, preferably having 8 to 24 carbon atoms and in particular having 18 carbon atoms. In addition, R can contain polymerizable and / or functional groups.

[0020] According to one embodiment, the metal oxides and / or metal hydroxides may be based on metals of groups HA, IVB, VIIB, VIIIB, IB, HB, IIIA and IVA, preferably the metals AI, Sn, Mg, Ca, Zn, Fe, Ti and in particular the metals AI, Mg, Ca, Ti and Zn.

[0021] According to a further embodiment, the coating may also contain a binder material for improved particle fixation. The binder material may be selected as described above; for example, the binder material may be selected from citric acid, acrylic acid, or mixtures thereof.

[0022] Also part of the present invention is the coating according to the invention, applied to a non-textile surface, for example, to a substrate made of paper, cardboard, paperboard, cellulose, wood, and other fiber-based materials, or to a substrate based on ceramic, stone, metal, or plastic. Also part of the present invention are substrates made of paper, cardboard, paperboard, cellulose, wood, and other fiber-based materials, or substrates based on ceramic, stone, metal, or plastic, coated with a coating according to the invention. BRIEF DESCRIPTION OF THE CHARACTERS

[0023] The invention will now be described in detail with reference to exemplary embodiments thereof and the accompanying figures.

[0024] It shows: Fig. 1 Photographs of untreated (Fig. 1a) and inventively treated (Fig. 1b) printer paper 30 seconds after dripping on an ink solution (Example 1); Fig. 2 Photographs of untreated (Fig. 2a) and treated according to the invention (Fig. 2b) double-layer cardboard 30 seconds after dripping on an ink solution (Example 2); Fig. 3 Photographs of untreated (Fig. 3a) and treated according to the invention (Fig. 3b) two-ply kitchen roll 30 seconds after dripping on an ink solution (Example 3); Fig. 4 Photographs of an untreated (Fig. 4a) and a treated according to the invention (Fig. 4b) solid pine slat 30 seconds after Dripping an ink solution, as well as an untreated (Fig. 4c) and an inventively treated (Fig. 4d) pine slat 30 seconds after Immersion in an ink solution (Example 4); Fig. 5 Photographs of an untreated (Fig. 5a) and a particle board treated according to the invention (Fig. 5b) 30 seconds after Dripping an ink solution, as well as an untreated (Fig. 5c) and a particle board treated according to the invention (Fig. 5d) 30 seconds after Immersion in an ink solution (Example 5); Fig. 6 Photographs of an untreated (Fig. 6a) and a hardwood slat treated according to the invention (Fig. 6b) 30 seconds after dripping on an ink solution, as well as an untreated (Fig. 6c) and a hardwood slat treated according to the invention (Fig. 6d) 30 seconds after immersion in an ink solution (Example 6); Fig. 7 Photographs of an untreated (Fig. 7a) and a particle board treated according to the invention (Fig. 7b) 30 seconds after dripping on an ink solution, as well as an untreated (Fig. 7c) and a particle board treated according to the invention (Fig. 7d) 30 seconds after immersion in an ink solution (Example 7); Fig. 8 Photographs of an untreated (Fig. 8a) and a multiplex plate treated according to the invention (Fig. 8b) 30 seconds after dripping on an ink solution, as well as an untreated (Fig. 8c) and a multiplex plate treated according to the invention (Fig. 8d) 30 seconds after immersion in an ink solution (Example 8).

[0025] The following detailed description and references to the figures relate to exemplary embodiments of the present invention and are not to be considered as limiting the claims. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention encompasses the coating and modification of non-textile surfaces, preferably fiber-based materials such as paper, cardboard, paperboard, cellulose, or wood, as well as material surfaces based on ceramics, stone, metal, and plastics, with environmentally friendly compounds free of fluorine and petroleum-based organic polymers to generate a water-repellent effect. For this purpose, particles based on metal oxides and / or metal hydroxides of groups HA, IVB, VIIB, VIIIB, IB, HB, HIA, and IVA, preferably the metals Al, Sn, Mg, Ca, Zn, Fe, Ti, and in particular the metals Al, Mg, Ca, Ti, and Zn, are applied to said material surfaces. Depending on the application process, the particles range in size from 1 nm to 10 pm.If a binder material is additionally used for better particle fixation, this consists of biopolymers based on proteins, polysaccharides, lipids, cutins or suberins, preferably based on polysaccharides, lipids and cutins.

[0027] The surfaces coated with the particles and, optionally, binder material are then treated with hydrophobizing agents based on carboxylic acids and / or organophosphorus compounds, in particular compounds based on phosphoric acid esters or phosphonic acids of the general formula RCOOH, OP(OH)2OR, or OP(OH)2R, where R represents a hydrophobic radical in the form of aliphatic, branched or unbranched, alicyclic, or aromatic hydrocarbon groups with 5-40 carbon atoms, preferably with 8-24 carbon atoms, and in particular with 18 carbon atoms. Furthermore, R can also contain polymerizable functional groups.

[0028] The hydrophobic agents bind by forming bonds between the surface hydroxyl groups of the metal oxide / metal hydroxide particles and the carboxylic acid, phosphoric acid, or phosphonic acid groups of the hydrophobic compounds. Unlike silanes, these compounds offer the advantage of uncomplicated and rapid application with the same, or sometimes even better, stability. Furthermore, these compounds are non-toxic and environmentally friendly.

[0029] Furthermore, any combinations of the features and / or limitations described herein are part of the present invention, insofar as they are not mutually exclusive. The description of the invention relates to specific embodiments of the invention with the aim of illustrating them. The person skilled in the art will recognize that further modifications and Equivalents of the embodiments described herein are possible. Such modifications and equivalents also constitute part of the overall scope of the described invention. EXAMPLES

[0030] The hydrophobic agent according to the invention was applied to various substrates. The substrates were then tested for their water-repellent properties by visual analysis after applying drops of a mixture of commercially available blue fountain pen ink in tap water.

[0031] The substrates selected for the test series are shown in Table 1. Table 1:

[0032] Substrate samples 4 to 8 were first pretreated with an aqueous citric acid solution as a binder. Substrate samples 1 to 3 were not pretreated. In a first process step, particles of oxide aluminum with particle sizes ranging from 100 to 200 nm were applied to the substrate surfaces to a surface concentration, depending on the substrate, between 195 and 1,800 mg / m³. 2 The different surface concentrations given in Table 1 result from the different surface structures and properties of the fibrous substrate samples, with smooth substrate surfaces generally having lower particle surface concentrations than rough substrate surfaces.

[0033] In a next step, the substrate samples were immersed in a solution of octadecylphosphoric acid ester in ethanol (1 g / L) for 2 seconds each and then dried in air.

[0034] For the staining tests, a solution of 3 mL of commercially available fountain pen ink in 100 mL of tap water was prepared. Treated and untreated substrate samples were each sprinkled with a few drops of the ink solution. All samples and control samples (Examples 1 to 8) were visually inspected 30 seconds after the ink solution drops were applied. The results are shown in the attached figures.

[0035] Immersion tests were also conducted for the wood samples and wood reference samples (Examples 4 to 8). The samples and reference samples were immersed for 5 seconds each in an ink solution prepared as described above.

[0036] It was shown that, across all paper, cardboard, and wood samples, the coated samples exhibited significant liquid-repellent properties. The ink-based samples penetrated the untreated substrate samples during the short observation period, while they beaded up and did not penetrate the fibrous material of the treated substrate samples. This applies equally to both the drip-on and immersion tests.

Claims

PATENT CLAIMS 1. Coating and modification processes for non-textile surfaces, comprising the process steps Applying particles based on metal oxides and / or metal hydroxides of groups HA, IVB, VIIB, VIIIB, IB, HB, HIA and IVA to a non-textile surface, wherein the particles are in a size range of 1 nm to 10 pm, and after applying the metal oxide or metal hydroxide particles to the non-textile surface, coating with hydrophobing agents based on fluorine-free carboxylic acids, phosphoric acid esters and / or phosphonic acids.

2. Process according to claim 1, characterized in that the carboxylic acids, phosphoric acid esters and / or phosphonic acids are in the general form RCOOH, OP(OH)2OR or OP(OH)2R, where R represents a hydrophobic radical in the form of aliphatic, branched or unbranched, alicyclic or aromatic hydrocarbon groups having 5 to 40 carbon atoms, preferably having 8 to 24 carbon atoms and in particular having 18 carbon atoms.

3. Process according to claim 2, characterized in that R contains polymerizable and / or functional groups.

4. Method according to one of claims 1 to 3, characterized in that the non-textile surface comprises substrates of paper, cardboard, carton, pulp or wood and other fiber-based materials, as well as substrates based on ceramic, stone, metal or plastic, preferably paper, cardboard, carton, pulp or wood and other fiber-based materials.

5. Process according to one of claims 1 to 4, characterized in that the metal oxides and / or meta II hydroxides are based on metals of groups HA, IVB, VIIB, VIIIB, IB, HB, HIA and IVA, preferably the metals AI, Sn, Mg, Ca, Zn, Fe, Ti and in particular the metals AI, Mg, Ca, Ti and Zn.

6. Process according to one of claims 1 to 5, characterized in that the meta II oxides and / or metal hydroxides are present as particles having a size of 30 to 700 nm after application to the substrate.

7. Method according to one of claims 1 to 6, further comprising a step of inserting a binder material for better particle fixation.

8. The method of claim 7, wherein the binder material is selected from citric acid, acrylic acid and mixtures thereof.

9. Coating for non-textile surfaces, comprising particles based on metal oxides and / or metal hydroxides of groups IIA, IVB, VIIB, VIIIB, IB, HB, IIIA and IVA and a hydrophobizing agent based on fluorine-free carboxylic acids, phosphoric acid esters and / or phosphonic acids, wherein the particles are in a size range of 1 nm to 10 pm.

10. Coating according to claim 9, characterized in that the carboxylic acids, phosphoric acid esters and / or phosphonic acids are in the general form RCOOH, OP(OH)2OR or OP(OH)2R, where R represents a hydrophobic radical in the form of aliphatic, branched or unbranched, alicyclic or aromatic hydrocarbon groups having 5 to 40 carbon atoms, preferably having 8 to 24 carbon atoms and in particular having 18 carbon atoms.

11. Coating according to claim 10, characterized in that R contains polymerizable and / or functional groups.

12. Coating according to one of claims 9 to 11, characterized in that the metal oxides and / or metal hydroxides are based on metals of groups IIA, IVB, VIIB, VIIIB, IB, HB, IIIA and IVA, preferably the metals AI, Sn, Mg, Ca, Zn, Fe, Ti and in particular the metals AI, Mg, Ca, Ti and Zn.

13. Coating according to one of claims 9 to 12, characterized in that the metal oxides and / or metal hydroxides are present as particles having a size of 30 to 700 nm after application to the substrate.

14. Coating according to one of claims 9 to 13, further comprising a binder material for better particle fixation, for example wherein the binder material is selected from citric acid, acrylic acid and mixtures thereof.

15. Coating according to one of claims 9 to 14, on a non-textile surface, for example on a substrate of paper, cardboard, paperboard, cellulose or wood and other fiber-based materials, or a substrate based on ceramic, stone, metal or plastic.

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