A flexible ceramic coating and a method of making the same

Abstract

The application discloses a flexible ceramic coating and a preparation method thereof, wherein the flexible ceramic coating comprises the following components in parts by mass: nano ceramic slurry, pigment, carboxyl modified silica nanosphere, wet dispersant, thickening agent, silane, salicylic acid and water; the flexible ceramic coating prepared by the application has the characteristics of high stain resistance and easy cleaning, bending resistance, strong impact resistance and strong adhesion, and the surface of a base material does not need to be polished by using sandpaper during use.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a flexible ceramic coating and its preparation method. Background Technology

[0002] Existing ceramic coatings primarily consist of a chemical reaction between nano-silica sol and siloxanes. The siloxanes undergo continuous hydrolysis and condensation, resulting in a highly cross-linked inorganic network (with a hardness as high as 9H) formed by the interconnection and entanglement of components. However, due to the presence of a hydration layer on the surface of the nano-silica sol, the disappearance of this layer during the drying process causes the coating to shrink in volume, increasing internal stress and leading to high brittleness, poor toughness, and low adhesion. During the coating process, the substrate must be pre-formed before coating; otherwise, even slight bending of the substrate can cause the ceramic coating to crack and break. Furthermore, the coating requires extreme care during use; bumps and impacts can damage it, causing cracking and peeling. Summary of the Invention

[0003] To address the aforementioned problems, one objective of this invention is to provide a flexible ceramic coating comprising the following components in parts by weight:

[0004] 7-27 parts nano-ceramic slurry, 3.8-4.6 parts pigment, 3-7 parts carboxyl-modified silica nanospheres, 0.3-0.7 parts wetting and dispersing agent, 0.4-0.8 parts thickener, 3.4-5.4 parts silane, 0.1-0.5 parts salicylic acid, 54-82 parts water;

[0005] The nano-ceramic slurry is composed of the following components in parts by weight:

[0006] 16-20 parts nano-ceramic powder, 4-12 parts methyl epichlorohydrin, 5-9 parts allyl alcohol, 1-3 parts sodium hydroxide, and 60-70 parts hot water at 80-90℃.

[0007] Another objective of this invention is to provide a method for preparing flexible ceramic coatings, comprising the following steps:

[0008] Preparation of nano-ceramic slurry;

[0009] Preparation of carboxyl-modified silica nanospheres;

[0010] Pigment, carboxyl-modified silica nanospheres, wetting and dispersing agent, thickener, silane and water are mixed and heated to 40~60℃, then nano-ceramic slurry is added and stirred for 0.5~1h. Salicylic acid is added while stirring, and the mixture is cooled to obtain a flexible ceramic coating.

[0011] Furthermore, the method for preparing nano-ceramic slurry includes the following steps:

[0012] Mix methyl epichlorohydrin and sodium hydroxide, stir until homogeneous, then add propylene alcohol, nano-ceramic powder and hot water at 80-90℃, and continue stirring for 4-6 hours to obtain nano-ceramic slurry.

[0013] Furthermore, the method for preparing carboxyl-modified silica nanospheres includes the following steps:

[0014] Mix 1-3 parts tetraethyl orthosilicate, 1-3 parts concentrated ammonia, 0.5-1.5 parts pure water, and 40-60 parts 80-90% ethanol, and heat to 40-60℃ while stirring. Then add 0.5-1.5 parts tetraethyl orthosilicate and continue stirring for 1-3 hours for hydrolysis. Centrifuge and filter to collect the residue. Wash the residue with pure water until pH=7 to obtain SiO2 nanoparticles. Take 10-20 parts of SiO2 nanoparticles and 0.1-0.3 parts of γ-aminopropyltriethoxysilane and add them to 30-50 parts of ethanol and stir for 1-3 hours. Filter to collect the residue and wash it with ethanol to obtain amino-modified SiO2 nanoparticles. Add 10-20 parts of amino-modified SiO2 nanoparticles and 0.1-0.3 parts of trimellitic anhydride to 30-50 parts of tetrahydrofuran and stir for 6-8 hours. Filter to collect the residue and wash it with water to obtain carboxyl-modified silica nanospheres. In the preparation of carboxyl-modified silica nanospheres, concentrated ammonia was used as a catalyst and tetraethoxysilane was used as a raw material. Silica nanospheres were prepared by the Stober sol-gel method. The surface of the silica nanospheres was further modified with γ-aminopropyltriethoxysilane, and then reacted with trimellitic anhydride to obtain carboxyl-modified silica nanospheres.

[0015] Furthermore, the pigment can be any one of pearlescent pigment, fluorescent pigment, or metallic pigment.

[0016] Furthermore, the silane is any one of methyltrimethoxysilane, methyltriethoxysilane, or dimethyldimethoxysilane.

[0017] Furthermore, the nano-ceramic powder is any one of BaTiO3, PbTiO3, and CaTiO3.

[0018] Furthermore, the wetting and dispersing agent is an ammonium acrylate dispersant.

[0019] Furthermore, the thickener is any one of methylcellulose, carboxymethylcellulose, and sodium carboxymethylcellulose.

[0020] The beneficial effects are as follows: This invention is based on nanogel-sol technology, which obtains a nanoceramic slurry by undergoing a ring-opening polymerization reaction of methyl epichlorohydrin, allyl alcohol, sodium hydroxide, nano-ceramic powder, and hot water at 80-90℃. This slurry is a highly branched three-dimensional network structure coated with nano-ceramic powder, which has good hydrophilicity, biocompatibility, and a large number of functionalizable hydroxyl groups, and has high adhesion to various substances, which can significantly improve the adhesion of ceramic coatings. Furthermore, this nanoceramic slurry can further undergo a grafting reaction with carboxyl-modified silica nanospheres and silanes under the action of salicylic acid catalyst. When the coating is applied, the drying of the coating will cause changes in the three-dimensional network structure of this nanoceramic slurry, releasing the nano-ceramic powder and reacting with carboxyl-modified silica nanospheres and silanes to crosslink and form a film. This film has an extremely high crosslinking density, which can not only resist the penetration of small molecule stains into the interior of the coating, but also increase the toughness of the ceramic coating, significantly reduce the shrinkage stress generated during the curing process of the ceramic coating, improve the brittle connection of the inorganic network, and improve the bending and impact resistance of the ceramic coating. Therefore, the flexible ceramic coating prepared by this invention not only has extremely high stain resistance and easy cleaning performance, but also has the characteristics of bending resistance, strong impact resistance and strong adhesion. When using it, there is no need to sand the surface of the substrate. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand this invention.

[0022] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the specific embodiments of the invention without inventive effort are within the protection scope of the invention.

[0023] In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0024] Raw material source:

[0025] Ammonium acrylate dispersant, purchased from Guangzhou Huixiang Chemical Co., Ltd.;

[0026] Methylcellulose, hydroxymethylcellulose and dimethyldimethoxysilane were all purchased from Hunan Yunbang Biotechnology Co., Ltd.

[0027] Sodium carboxymethyl cellulose was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.

[0028] Methyltrimethoxysilane was purchased from Nanjing Jingtianwei Chemical Co., Ltd.

[0029] Methyltriethoxysilane, purchased from Shanghai Tongyuan Chemical Co., Ltd.;

[0030] Salicylic acid, purchased from Shandong Longhui Chemical Co., Ltd.

[0031] Nano-ceramic powder, purchased from Beijing Yanbang New Materials Technology Co., Ltd.;

[0032] Methyl epichlorohydrin was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0033] Acrylic alcohol was purchased from Shanghai Siluntai New Materials Development Co., Ltd.

[0034] Sodium hydroxide was purchased from Xuzhou Xinchangsheng Chemical Co., Ltd.

[0035] Tetraethyl orthosilicate, purchased from Tianjin Fuchen Chemical Reagent Factory;

[0036] Concentrated ammonia solution was purchased from Shanghai Reagent Factory No. 1.

[0037] γ-aminopropyltriethoxysilane (APTES), trimellitic anhydride (TMA), and ethanol

[0038] All were purchased from Shanghai Sinopharm Group Chemical Reagent Company;

[0039] Tetrahydrofuran, purchased from Shandong Mantanghong New Materials Co., Ltd.;

[0040] Silica, purchased from Shandong Gushuo Biotechnology Co., Ltd.;

[0041] All other reagents were commercially available.

[0042] Example 1

[0043] This embodiment provides a method for preparing flexible ceramic coatings, including the following steps:

[0044] Preparation of nano-ceramic slurry: Mix 8 parts of methyl epichlorohydrin and 2 parts of sodium hydroxide, stir evenly, then add 7 parts of allyl alcohol, 18 parts of nano-ceramic powder and 65 parts of hot water at 80~90℃, and continue stirring for 5 hours to obtain nano-ceramic slurry;

[0045] Preparation of carboxyl-modified silica nanospheres: 2 parts tetraethyl orthosilicate, 2 parts concentrated ammonia, 1 part pure water and 50 parts 85% ethanol were mixed and heated to 50°C while stirring. Then 1 part tetraethyl orthosilicate was added and stirring was continued for 2 hours for hydrolysis. The residue was collected by centrifugation and filtration. The residue was washed with pure water until pH=7 to obtain SiO2 nanoparticles. 15 parts of SiO2 nanoparticles and 0.2 parts of γ-aminopropyltriethoxysilane were added to 40 parts of ethanol and stirred for 2 hours. The residue was collected by filtration and washed with ethanol to obtain amino-modified SiO2 nanoparticles. 15 parts of amino-modified SiO2 nanoparticles and 0.2 parts of trimellitic anhydride were added to 40 parts of tetrahydrofuran and stirred for 7 hours. The residue was collected by filtration and washed with water to obtain carboxyl-modified silica nanospheres.

[0046] Mix 4.2 parts pigment, 5 parts carboxyl-modified silica nanospheres, 0.5 parts wetting and dispersing agent, 0.6 parts thickener, 4.4 parts silane and 68 parts water and heat to 50°C. Then add 17 parts nano-ceramic slurry and stir for 0.75 hours. While stirring, add 0.3 parts salicylic acid and cool to obtain a flexible ceramic coating.

[0047] Among them, the pigment is a pearlescent pigment, the silane is methyltrimethoxysilane, the nano-ceramic powder is BaTiO3, the wetting and dispersing agent is ammonium acrylate dispersant, and the thickener is methylcellulose.

[0048] Example 2

[0049] This embodiment provides a method for preparing flexible ceramic coatings, including the following steps:

[0050] Preparation of nano-ceramic slurry: Mix 12 parts of methyl epichlorohydrin and 3 parts of sodium hydroxide, stir evenly, then add 9 parts of propylene alcohol, 20 parts of nano-ceramic powder and 60 parts of 90℃ hot water, and continue stirring for 6 hours to obtain nano-ceramic slurry;

[0051] Preparation of carboxyl-modified silica nanospheres: 3 parts tetraethyl orthosilicate, 3 parts concentrated ammonia, 1.5 parts pure water, and 40 parts 90% ethanol were mixed and heated to 60℃ while stirring. Then, 1.5 parts tetraethyl orthosilicate were added, and stirring was continued for 3 hours for hydrolysis. The residue was collected by centrifugation and filtration. The residue was washed with pure water until pH=7 to obtain SiO2 nanoparticles. 20 parts of SiO2 nanoparticles and 0.3 parts of γ-aminopropyltriethoxysilane were added to 50 parts of ethanol and stirred for 3 hours. The residue was collected by filtration and washed with ethanol to obtain amino-modified SiO2 nanoparticles. 20 parts of amino-modified SiO2 nanoparticles and 0.3 parts of trimellitic anhydride were added to 50 parts of tetrahydrofuran and stirred for 8 hours. The residue was collected by filtration and washed with water to obtain carboxyl-modified silica nanospheres.

[0052] Mix 4.6 parts pigment, 7 parts carboxyl-modified silica nanospheres, 0.7 parts wetting and dispersing agent, 0.8 parts thickener, 5.4 parts silane and 54 parts water and heat to 60°C. Then add 27 parts nano-ceramic slurry and stir for 1 hour. While stirring, add 0.5 parts salicylic acid and cool to obtain flexible ceramic coating.

[0053] The pigment is a fluorescent pigment, the silane is methyltriethoxysilane, the nano-ceramic powder is PbTiO3, the wetting and dispersing agent is ammonium acrylate dispersant, and the thickener is hydroxymethyl cellulose.

[0054] Example 3

[0055] This embodiment provides a method for preparing flexible ceramic coatings, including the following steps:

[0056] Preparation of nano-ceramic slurry: Mix 4 parts of methyl epichlorohydrin and 1 part of sodium hydroxide, stir evenly, then add 5 parts of allyl alcohol, 16 parts of nano-ceramic powder and 70 parts of 80℃ hot water, and continue stirring for 4 hours to obtain nano-ceramic slurry.

[0057] Preparation of carboxyl-modified silica nanospheres: 1 part tetraethyl orthosilicate, 1 part concentrated ammonia, 0.5 part pure water and 60 parts 80% ethanol were mixed and heated to 40℃ while stirring. Then 0.5 part tetraethyl orthosilicate was added and stirring was continued for 1 hour for hydrolysis. The residue was collected by centrifugation and filtration. The residue was washed with pure water until pH=7 to obtain SiO2 nanoparticles. 10 parts SiO2 nanoparticles and 0.1 part γ-aminopropyltriethoxysilane were added to 30 parts ethanol and stirred for 1 hour. The residue was collected by filtration and washed with ethanol to obtain amino-modified SiO2 nanoparticles. 10 parts amino-modified SiO2 nanoparticles and 0.1 part trimellitic anhydride were added to 30 parts tetrahydrofuran and stirred for 6 hours. The residue was collected by filtration and washed with water to obtain carboxyl-modified silica nanospheres.

[0058] Mix 3.8 parts pigment, 3 parts carboxyl-modified silica nanospheres, 0.3 parts wetting and dispersing agent, 0.4 parts thickener, 3.4 parts silane and 82 parts water and heat to 40°C. Then add 7 parts nano-ceramic slurry and stir for 0.5 hours. While stirring, add 0.1 parts salicylic acid and cool to obtain flexible ceramic coating.

[0059] The pigment is a metallic pigment, the silane is dimethyldimethoxysilane, the nano-ceramic powder is CaTiO3, the wetting and dispersing agent is ammonium acrylate dispersant, and the thickener is sodium hydroxymethyl cellulose.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that 17 parts of nano-ceramic powder are used to replace 17 parts of nano-ceramic slurry in Example 1, while the other components and experimental steps are the same as in Example 1.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that 5 parts of silica were used to replace 5 parts of carboxyl-modified silica nanospheres in Example 1. All other components and experimental steps were the same as in Example 1.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 1 is that the amount of water was increased from 68 parts to 68.3 parts, and salicylic acid was not added. All other components and experimental procedures were the same as in Example 1.

[0066] Product testing

[0067] The ceramic coatings prepared in Examples 1-3 and Comparative Examples 1-3 were sprayed onto specified test plates and cured to obtain coatings. The performance of all coatings was tested, and the results are shown in Table 1 below.

[0068] Test method:

[0069] Stain resistance: Tested according to HG / T4756-2014;

[0070] Water contact angle: Using a contact angle measuring instrument, select 5 points to measure the contact angle. After the water droplet contacts the sample, the test is completed within 3~5 seconds, and then the arithmetic mean is taken.

[0071] Coating hardness: Pencil hardness was tested according to GB / T6739—2006;

[0072] Coating adhesion: Tested according to GB 1720—1989 using the cross-cut test method;

[0073] Impact resistance of the coating: tested according to GB1732—1993;

[0074] Gloss: Tested according to GB 1743—2007;

[0075] Flexibility: Tested according to GB / T1731—1993.

[0076] Table 1. Performance test results of the ceramic coatings obtained in the above embodiments and comparative examples.

[0077]

[0078] As can be seen from the table above, the coatings prepared in Examples 1 to 3 of this application all have a water contact angle greater than 150 degrees, exhibiting excellent superhydrophobicity and self-cleaning properties. Their stain resistance all reach level 1, film hardness all reach 8H, film adhesion all reach level 1, film impact resistance all exceed 50cm, and flexibility all reach 1mm. It is evident that the flexible ceramic coating of this application has the characteristics of stain resistance and easy cleaning, high gloss, high hardness, good adhesion, bending resistance, and strong impact resistance. Furthermore, the performance data of Example 1 are superior to those of Examples 2 and 3. Further comparative analysis of the data from Example 1 and Comparative Examples 1-3 revealed that in Comparative Example 1, replacing the nano-ceramic slurry in Example 1 with ordinary nano-ceramic powder resulted in the failure to form a highly branched three-dimensional network structure coated with nano-ceramic powder, leading to increased coating hardness and decreased adhesion and impact resistance to the substrate. In Comparative Example 2, replacing the carboxyl-modified silica nanospheres in Example 1 with ordinary silica prevented the grafting reaction with the nano-ceramic slurry, resulting in increased hardness, poor flexibility, and decreased adhesion and impact resistance to the substrate. In Comparative Example 3, the absence of the catalyst salicylic acid prevented the nano-ceramic slurry from further grafting with the carboxyl-modified silica nanospheres and silane, resulting in increased coating hardness, poor flexibility, decreased adhesion and impact resistance to the substrate, and poor gloss.

[0079] In summary, the components of this application work synergistically to obtain a flexible ceramic coating with extremely high stain resistance, easy cleaning, bending resistance, good adhesion, and strong impact resistance. It does not require sanding the substrate surface during use, is simple to operate, and is highly practical. It can be applied to household appliances, kitchenware, interior decoration, or exterior walls of buildings.

[0080] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A flexible ceramic coating, characterized in that, The following components are included in parts by weight: 7-27 parts nano-ceramic slurry, 3.8-4.6 parts pigment, 3-7 parts carboxyl-modified silica nanospheres, 0.3-0.7 parts wetting and dispersing agent, 0.4-0.8 parts thickener, 3.4-5.4 parts silane, 0.1-0.5 parts salicylic acid, 54-82 parts water; The nano-ceramic slurry is composed of the following components in parts by mass: 16-20 parts nano-ceramic powder, 4-12 parts methyl epichlorohydrin, 5-9 parts allyl alcohol, 1-3 parts sodium hydroxide, and 60-70 parts hot water at 80-90℃.

2. The flexible ceramic coating according to claim 1, characterized in that, The pigment is any one of pearlescent pigment, fluorescent pigment, or metallic pigment.

3. The flexible ceramic coating according to claim 1, characterized in that, The silane is any one of methyltrimethoxysilane, methyltriethoxysilane, and dimethyldimethoxysilane.

4. The flexible ceramic coating according to claim 1, characterized in that, The nano-ceramic powder is any one of BaTiO3, PbTiO3, and CaTiO3.

5. The flexible ceramic coating according to claim 1, characterized in that, The wetting and dispersing agent is an ammonium acrylate dispersant.

6. The flexible ceramic coating according to claim 1, characterized in that, The thickener is any one of methylcellulose, hydroxymethylcellulose, and sodium hydroxymethylcellulose.

7. The method for preparing the flexible ceramic coating according to claim 1, characterized in that, Includes the following steps: Preparation of the nano-ceramic slurry; Preparation of the carboxyl-modified silica nanospheres; The pigment, carboxyl-modified silica nanospheres, wetting and dispersing agent, thickener, silane and water are mixed and heated to 40~60℃, then the nano-ceramic slurry is added, and the mixture is stirred for 0.5~1h. While stirring, the salicylic acid is added, and the mixture is cooled to obtain the flexible ceramic coating.

8. The method for preparing flexible ceramic coatings according to claim 7, characterized in that, The method for preparing the nano-ceramic slurry includes the following steps: The methyl epichlorohydrin and sodium hydroxide are mixed and stirred evenly. Then, the allyl alcohol, nano-ceramic powder and hot water at 80-90°C are added, and stirring is continued for 4-6 hours to obtain the nano-ceramic slurry.

9. The method for preparing flexible ceramic coatings according to claim 7, characterized in that, The method for preparing carboxyl-modified silica nanospheres includes the following steps: Mix 1-3 parts tetraethyl orthosilicate, 1-3 parts concentrated ammonia, 0.5-1.5 parts pure water, and 40-60 parts 80-90% ethanol, and heat to 40-60℃ while stirring. Then add 0.5-1.5 parts tetraethyl orthosilicate and continue stirring and hydrolyzing for 1-3 hours. Centrifuge and filter to collect the residue. Wash the residue with pure water until pH=7 to obtain SiO2 nanoparticles. Take 10-20 parts of SiO2 nanoparticles and 0.1-0.3 parts of γ-aminopropyltriethoxysilane and add them to 30-50 parts of ethanol and stir for 1-3 hours. Filter to collect the residue and wash it with ethanol to obtain amino-modified SiO2 nanoparticles. Add 10-20 parts of the amino-modified SiO2 nanoparticles and 0.1-0.3 parts of trimellitic anhydride to 30-50 parts of tetrahydrofuran and stir for 6-8 hours. Filter to collect the residue and wash it with water to obtain the carboxyl-modified silica nanospheres.

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