A method of forming a coating on a substrate

Abstract

The application provides a kind of enamel coating and its preparation method, the preparation method includes: inorganic nanometer microspheres and first silane coupling agent are mixed, grafting reaction is carried out, and modified inorganic nanometer microspheres are obtained, then modified inorganic nanometer microspheres and silicon resin material are mixed, and enamel coating is obtained, wherein the mass percentage of modified inorganic nanometer microspheres in enamel coating is 12%-40%, then the enamel coating is coated on the surface of enamel, and after drying treatment and curing crosslinking, the enamel coating is obtained. The enamel coating prepared by the method has high hardness, excellent easy-to-clean, high temperature resistance and acid resistance.

Description

Technical Field

[0001] This invention relates to an enamel coating and its preparation method, belonging to the technical field of metal and non-metal surface coatings. Background Technology

[0002] Enamel is a composite material formed by coating a metal substrate with silicate glass enamel and firing it at high temperatures. Enamel possesses excellent chemical stability and mechanical strength and is widely used in the culinary field. However, enamel is hydrophilic, which causes food to easily adhere to its surface during cooking, increasing the difficulty of cleaning.

[0003] CN115975408A discloses a high-temperature resistant and easy-to-clean inorganic coating, the raw material composition of which includes modified silicate, phosphate, ceramic material, metal powder, cobalt oxide, graphite and polyethylene glycol. By using a variety of inorganic materials, the inorganic coating has excellent high-temperature resistance and corrosion resistance.

[0004] CN117402511A discloses an easy-to-clean nano-superhydrophilic silicate coating for enamel panels. The raw materials for its preparation include nano-aluminum sol, silica sol, nano-titanium sol, polysilicate modified compound and water. The nano-superhydrophilic silicate coating has good cleanability under room temperature conditions. When oil stains adhere to the surface, they can be easily removed by wiping with water. However, the coating has poor water resistance.

[0005] CN116948189A discloses a hydrophobic and oleophobic easy-to-clean coating material for AG glass. Its raw material composition includes fluorine-modified organopolysilazane, solvent and silane coupling agent. The fluorine-modified polysilazane enhances the bonding between the end and the glass, forming a coating with excellent hydrophobic and oleophobic properties on the glass surface. However, this coating is applied to anti-glare glass, and the fluorine in the fluorine-modified polysilazane causes significant environmental pollution.

[0006] The aforementioned enamel coatings cannot simultaneously possess high hardness, excellent easy-to-clean properties, high-temperature resistance, and acid resistance, making it difficult to meet the easy-to-clean requirements of ovens, baking pans, and baking trays when operating at temperatures of 200-300℃. Therefore, how to provide a preparation method that enables enamel coatings to possess high hardness, excellent easy-to-clean properties, high-temperature resistance, and acid resistance is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] This invention provides a method for preparing an enamel coating, wherein the enamel coating prepared by the method has high hardness, excellent easy cleaning properties, high temperature resistance and acid resistance.

[0008] The present invention also provides an enamel coating that simultaneously possesses high hardness, excellent easy cleaning properties, high temperature resistance, and acid resistance.

[0009] In a first aspect, the present invention provides a method for preparing an enamel coating, comprising:

[0010] 1) Inorganic nanospheres and a first silane coupling agent are mixed and grafted to obtain modified inorganic nanospheres;

[0011] 2) The modified inorganic nanospheres and silicone resin material are mixed to obtain an enamel coating;

[0012] 3) The enamel coating is applied to the enamel surface, and then dried and cured to obtain the enamel coating layer;

[0013] The modified inorganic nanospheres in the enamel coating have a mass percentage of 12%-40%.

[0014] The preparation method described above, wherein the inorganic nanospheres comprise SiO2 nanospheres and / or ZrO2 nanospheres; and / or,

[0015] The first silane coupling agent includes γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane.

[0016] In the preparation method described above, the mass ratio of the SiO2 nanospheres to the ZrO2 nanospheres is (1~5):(1~5).

[0017] In the preparation method described above, the particle size of the inorganic nanospheres is 10 nm to 30 nm.

[0018] In the preparation method described above, the silicone resin material is a modified silicone resin obtained by modifying an organosilicon resin with a second silane coupling agent.

[0019] In the preparation method described above, the mass ratio of the organosilicon resin to the total mass of the organosilicon resin and the second silane coupling agent is 98%-99.2%; and / or,

[0020] The mass ratio of the second silane coupling agent to the total mass of the organosilicon resin and the second silane coupling agent is 0.8%-2%.

[0021] The preparation method described above, wherein the organosilicon resin comprises polydimethylsiloxane and / or polymethylsiloxane; and / or,

[0022] The second silane coupling agent includes γ-glycidoxypropyltrimethoxysilane.

[0023] In the preparation method described above, the thickness of the enamel coating is 0.3 μm-2 μm.

[0024] In the preparation method described above, the drying conditions are: a temperature of 70-90°C and a time of 20-30 min; and / or,

[0025] The curing and crosslinking conditions are: temperature 250-320℃, time 10-30min.

[0026] Secondly, the present invention provides an enamel coating, which is prepared by the above-described preparation method.

[0027] This invention first involves a grafting reaction of inorganic nanospheres and a first silane coupling agent to obtain modified inorganic nanospheres. Then, the modified inorganic nanospheres are mixed with a silicone resin material to obtain an enamel coating. This enamel coating is then applied to the surface of an enamel enamel layer, followed by drying and curing to obtain an enamel coating with a cross-linked network structure. The enamel coating prepared by this method exhibits high hardness, excellent easy cleaning properties, high temperature resistance, and acid resistance. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] This invention provides a method for preparing an enamel coating, comprising:

[0030] 1) Inorganic nanospheres and a first silane coupling agent are mixed and grafted to obtain modified inorganic nanospheres;

[0031] 2) Modified inorganic nanospheres and silicone resin materials are mixed to obtain enamel coating;

[0032] 3) Apply enamel coating to the enamel surface, and then dry and cure it to obtain the enamel coating.

[0033] Specifically, the method for preparing the enamel coating of the present invention includes: 1) mixing inorganic nanospheres and a first silane coupling agent, wherein the first silane coupling agent and the hydroxyl groups on the surface of the inorganic nanospheres undergo dehydration condensation, and a grafting reaction is carried out to obtain modified inorganic nanospheres. On the one hand, the modified inorganic nanospheres can be uniformly dispersed in the silicone resin material; on the other hand, the first silane coupling agent can form a denser enamel coating with the silicone resin material through bonding.

[0034] 2) Modified inorganic nanospheres and silicone resin materials are mixed to obtain enamel coating;

[0035] 3) Apply enamel coating to the enamel surface, then dry it to remove moisture and solvent from the enamel coating, and then cure and crosslink it so that the modified inorganic nanospheres are uniformly embedded in the crosslinked network formed by the silicone resin material, thus obtaining an enamel coating with a dense crosslinked network structure.

[0036] The modified inorganic nanospheres in the enamel coating of this invention have a mass percentage of 12%-40%, for example, 12%, 16%, 18%, 20%, 25%, 30%, 35%, or 40%. Furthermore, the silicone resin material in the enamel coating has a mass percentage of 60%-88%, for example, 60%, 65%, 70%, 75%, 80%, or 88%. By adjusting the amount of modified inorganic nanospheres and silicone resin material added, an enamel coating with higher smoothness and density can be obtained.

[0037] In some embodiments, in step 1), inorganic nanospheres are first dispersed in an organic solvent, then a first silane coupling agent is added and stirred to carry out a grafting reaction. Modified inorganic nanospheres are obtained by centrifugation. The organic solvent includes ethanol and / or butanol, and the mass ratio of inorganic nanospheres to the first silane coupling agent is (24-499):1, for example, 24:1, 40:1, 80:1, 150:1, 200:1, 300:1, 400:1, or 499:1.

[0038] In some embodiments, in step 2), the modified inorganic nanospheres are slowly added to the silicone resin material, ultrasonically dispersed at 15-30°C for 10-30 minutes, and stirred evenly to obtain an enamel coating.

[0039] In some embodiments, in step 3), the enamel coating is uniformly applied to the enamel surface by wiping, dipping, or spraying, and then dried, cured, cross-linked, and cooled to obtain the enamel coating.

[0040] Modified inorganic nanospheres are uniformly embedded in a cross-linked network formed by silicone resin material through grafting reaction and curing cross-linking, thereby forming a dense and smooth enamel coating on the enamel surface. This prevents the penetration of water, chemicals, and other contaminants, and reduces the adhesion of grease and dirt. The non-polar groups in the silicone resin material further improve the hydrophobicity of the enamel coating. The addition of modified inorganic nanospheres significantly improves the high-temperature resistance, hardness, and wear resistance of the enamel coating. The enamel coating prepared by this method possesses high hardness, excellent easy cleaning, high-temperature resistance, and acid resistance. Furthermore, the preparation method is simple to operate and suitable for widespread application.

[0041] In this invention, the inorganic nanospheres include SiO2 nanospheres and / or ZrO2 nanospheres. That is, the inorganic nanospheres can be SiO2 nanospheres, ZrO2 nanospheres, or both. SiO2 nanospheres possess high hardness, excellent thermal stability, and chemical inertness, which can impart high hardness, excellent high-temperature resistance, and acid resistance to the enamel coating. ZrO2 nanospheres possess excellent water resistance, which can improve the hydrophobicity of the enamel coating, reduce the adhesion of dirt and water stains, and make the enamel coating easier to clean.

[0042] Furthermore, the first silane coupling agent includes γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane. That is, the first silane coupling agent can be γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or it can simultaneously include both γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. The methoxy / ethoxy groups in the aforementioned first silane coupling agent undergo dehydration condensation with the hydroxyl groups on the surface of the inorganic nanospheres, resulting in a grafting reaction to obtain modified inorganic nanospheres. This allows the modified inorganic nanospheres to be uniformly dispersed in the silicone resin material. Simultaneously, the first silane coupling agent and the silicone resin material form a denser enamel coating through bonding.

[0043] In some embodiments, the mass ratio of SiO2 nanospheres to ZrO2 nanospheres is selected to further improve the hardness, ease of cleaning, high temperature resistance, and acid resistance of the enamel coating. The mass ratio of SiO2 nanospheres to ZrO2 nanospheres is (1~5):(1-5), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 2:3, 2:5, 3:1, 3:2, 3:4, 3:5, 4:1, 4:3, 4:5, 5:1, 5:2, 5:3, 5:4.

[0044] In this invention, the particle size of the inorganic nanospheres is 10nm~30nm, for example, 10nm, 15nm, 20nm, 25nm, or 30nm, which can improve the density and surface smoothness of the enamel coating.

[0045] In some embodiments, the silicone resin material is a modified silicone resin obtained by modifying an organosilicon resin with a second silane coupling agent. By using the second silane coupling agent to modify the organosilicon resin, the methoxy group in the second silane coupling agent and the siloxane group in the organosilicon resin undergo a condensation reaction to form a cross-linked structure, which can improve the cross-linking density of the enamel coating.

[0046] According to the technical solution of the present invention, the ratio of organosilicon resin and second silane coupling agent is optimized to obtain an enamel coating with higher crosslinking density. The mass ratio of organosilicon resin to the total mass ratio of organosilicon resin and second silane coupling agent is 98%-99.2%, for example, 98%, 98.2%, 98.4%, 98.6%, 98.8%, 99%, 99.2%, and the mass ratio of second silane coupling agent to the total mass ratio of organosilicon resin and second silane coupling agent is 0.8%-2%, for example, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%.

[0047] In some embodiments, the silicone resin includes polydimethylsiloxane and / or polymethylsiloxane; that is, the silicone resin can be polydimethylsiloxane, polymethylsiloxane, or both. Both polydimethylsiloxane and polymethylsiloxane possess excellent flexibility, heat resistance, and hydrophobicity, which can improve the abrasion resistance, ease of cleaning, and high-temperature resistance of enamel coatings.

[0048] Furthermore, the second silane coupling agent includes γ-glycidoxypropyltrimethoxysilane, which contains epoxy and methoxy groups. By using it to modify organosilicon resin, the crosslinking density of the enamel coating can be further improved.

[0049] In this invention, the thickness of the enamel coating is 0.3μm-2μm, for example, it can be 0.3μm, 0.5μm, 0.7μm, 0.9μm, 1.2μm, 1.5μm, 1.8μm, or 2μm. This allows the enamel coating to possess excellent easy-to-clean properties, high-temperature resistance, and acid resistance while saving enamel paint and reducing costs. The thickness of the enamel coating in this invention refers to the thickness of the enamel coating formed after drying and cross-linking curing.

[0050] According to the technical solution of the present invention, the drying conditions are: temperature of 75-90℃ and time of 20-30min, which efficiently removes moisture and solvent from enamel coating while saving energy.

[0051] Furthermore, the curing and crosslinking conditions are: temperature of 250-320℃ and time of 10-30min, so that the modified inorganic nanospheres and silicone resin materials can be fully cured and crosslinked, thereby obtaining an enamel coating with high hardness, excellent easy cleaning, high temperature resistance and acid resistance.

[0052] Secondly, the present invention proposes an enamel coating, which is prepared by the preparation method of the first aspect. This enamel coating simultaneously possesses high hardness, excellent easy cleaning properties, high temperature resistance, and acid resistance.

[0053] The present invention will be described in detail below through specific embodiments:

[0054] Example 1:

[0055] The enamel coating in this embodiment is prepared by a method including the following steps:

[0056] 1) Disperse 20g of SiO2 nanospheres and 4g of ZrO2 nanospheres in 20ml of ethanol, add 0.5g of KH550, carry out the grafting reaction, and separate the solid components by centrifugation to obtain modified inorganic nanospheres.

[0057] 2) Mix 100g of polydimethylsiloxane (Shanghai Titan Technology Co., Ltd., 9016-00-6) and 1.0g of KH550 to react and obtain silicone resin material;

[0058] 3) Slowly add 20g of modified inorganic nanospheres to 100g of silicone resin material, stir evenly, and ultrasonically disperse at 20℃ for 30min to obtain enamel coating.

[0059] 4) Apply the enamel coating to the enamel surface by spraying, dry at 80°C for 20 min, cure and crosslink at 250°C for 20 min, and cool to 25°C to obtain the enamel coating.

[0060] The particle size of SiO2 nanospheres is 30nm, the particle size of ZrO2 nanospheres is 30nm, and the spraying conditions are as follows: the spraying pressure of the enamel coating is 0.5MPa, the spraying temperature is 25℃, the wet film thickness is 1.2μm, and the thickness of the enamel coating is 0.8μm.

[0061] Example 2:

[0062] The enamel coating in this embodiment is prepared by a method including the following steps:

[0063] 1) Disperse 10g of SiO2 nanospheres and 10g of ZrO2 nanospheres in 20ml of ethanol, add 0.6g of KH550, carry out the grafting reaction, and separate the solid components by centrifugation to obtain modified inorganic nanospheres.

[0064] 2) Mix 100g of polydimethylsiloxane (Shanghai Titan Technology Co., Ltd., 9016-00-6) and 0.8g of KH550 to react and obtain silicone resin material;

[0065] 3) Slowly add 15g of modified inorganic nanospheres to 100g of silicone resin material, stir evenly, and ultrasonically disperse at 20℃ for 30min to obtain enamel coating.

[0066] 4) Apply the enamel coating to the enamel surface by spraying, dry at 80°C for 20 min, cure and crosslink at 250°C for 20 min, and cool to 25°C to obtain the enamel coating.

[0067] The particle size of SiO2 nanospheres is 15nm, the particle size of ZrO2 nanospheres is 15nm, and the spraying conditions are as follows: the spraying pressure of the enamel coating is 0.7MPa, the spraying temperature is 18℃, the wet film thickness is 2.0μm, and the thickness of the enamel coating is 1.5μm.

[0068] Example 3:

[0069] The enamel coating in this embodiment is prepared by a method including the following steps:

[0070] 1) Disperse 5g SiO2 nanospheres and 20g ZrO2 nanospheres in 20ml ethanol, add 0.2g KH550, carry out grafting reaction, and centrifuge to separate the solid components to obtain modified inorganic nanospheres;

[0071] 2) Mix 100g of polydimethylsiloxane (Shanghai Titan Technology Co., Ltd., 9016-00-6) and 1.0g of KH560 to react and obtain silicone resin material;

[0072] 3) Slowly add 20g of modified inorganic nanospheres to 80g of silicone resin material, stir evenly, and ultrasonically disperse at 20℃ for 30min to obtain enamel coating;

[0073] 4) Apply the enamel coating to the enamel surface by spraying, dry at 80°C for 20 min, cure and crosslink at 250°C for 20 min, and cool to 25°C to obtain the enamel coating.

[0074] The particle size of SiO2 nanospheres is 10 nm, the particle size of ZrO2 nanospheres is 10 nm, and the spraying conditions are as follows: the spraying pressure of the enamel coating is 0.6 MPa, the spraying temperature is 22℃, the wet film thickness is 1.5 μm, and the thickness of the enamel coating is 0.9 μm.

[0075] Comparative Example 1

[0076] The enamel coating of this comparative example was prepared by a method including the following steps:

[0077] 1) Mix 100g of polydimethylsiloxane (Shanghai Titan Technology Co., Ltd., 9016-00-6) and 1.0g of KH560 to react and obtain silicone resin material;

[0078] 2) Slowly add 20g of SiO2 nanospheres and 4g of ZrO2 nanospheres to 100g of silicone resin material, stir evenly, and ultrasonically disperse at 20℃ for 30min to obtain enamel coating.

[0079] 3) Apply enamel coating to the enamel surface by spraying, dry at 80°C for 20 min, cure and crosslink at 250°C for 20 min, and cool to 25°C to obtain the enamel coating.

[0080] The particle size of SiO2 nanospheres is 30nm, the particle size of ZrO2 nanospheres is 30nm, and the spraying conditions are as follows: the spraying pressure of the enamel coating is 0.5MPa, the spraying temperature is 25℃, the wet film thickness is 1.2μm, and the thickness of the enamel coating is 0.8μm.

[0081] Performance testing:

[0082] (1) Ease of cleaning: According to GB / T24368-2009 standard, the water contact angle of the enamel coating surface in the test examples and comparative examples is 1. A water contact angle greater than 90° indicates that the surface of the enamel coating has good ease of cleaning. Liquids and dirt are not easy to adhere to the surface of the enamel coating. The results are shown in Table 1.

[0083] (2) High temperature resistance: The enamel coatings in the examples and comparative examples were kept at 300°C for 20 min. According to GB / T24368-2009 standard, the water contact angle 2 of the enamel coating surface in the examples and comparative examples after high temperature treatment was tested. The results are shown in Table 1.

[0084] (3) Hardness: The hardness of the enamel coating in the examples and comparative examples was tested according to GB / T6739-2022 / ISO15184-2020 standards. The results are shown in Table 1.

[0085] (4) Acid resistance: According to GB / T9989.1-2015 standard, the acid resistance of the enamel coating in the examples and comparative examples was tested, and the results are shown in Table 1.

[0086] Table 1

[0087]

[0088] As shown in Table 1, compared to Comparative Example 1, the water contact angle 1 of the enamel coating in Examples 1-3 of the present invention is greater than 100°, indicating that dirt does not easily adhere to the surface of the enamel coating, and the enamel coating has excellent easy-to-clean properties. Furthermore, the water contact angle 2 of the enamel coating in Examples 1-3 after high-temperature treatment is still greater than 100°, indicating that the enamel coating has excellent high-temperature resistance. Simultaneously, the enamel coating in Examples 1-3 exhibits high hardness and excellent acid resistance.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an enamel coating, characterized in that, The preparation method includes: 1) Inorganic nanospheres and a first silane coupling agent are mixed and grafted to obtain modified inorganic nanospheres; 2) The modified inorganic nanospheres and silicone resin material are mixed to obtain an enamel coating; 3) The enamel coating is applied to the enamel surface, and then dried and cured to obtain the enamel coating layer; The modified inorganic nanospheres in the enamel coating have a mass percentage of 12%-40%.

2. The preparation method according to claim 1, characterized in that, The inorganic nanospheres include SiO2 nanospheres and / or ZrO2 nanospheres; and / or, The first silane coupling agent includes γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the SiO2 nanospheres to the ZrO2 nanospheres is (1~5):(1~5).

4. The preparation method according to claim 1, characterized in that, The inorganic nanospheres have a particle size of 10 nm to 30 nm.

5. The preparation method according to any one of claims 1-4, characterized in that, The silicone resin material is a modified silicone resin obtained by modifying an organosilicon resin with a second silane coupling agent.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the organosilicon resin to the total mass of the organosilicon resin and the second silane coupling agent is 98%-99.2%; and / or, The mass ratio of the second silane coupling agent to the total mass of the organosilicon resin and the second silane coupling agent is 0.8%-2%.

7. The preparation method according to claim 5 or 6, characterized in that, The silicone resin includes polydimethylsiloxane and / or polymethylsiloxane; and / or, The second silane coupling agent includes γ-glycidoxypropyltrimethoxysilane.

8. The preparation method according to any one of claims 1-7, characterized in that, The thickness of the enamel coating is 0.3μm-2μm.

9. The preparation method according to any one of claims 1-8, characterized in that, The drying conditions are: temperature 70-90℃, time 20-30 min; and / or, The curing and crosslinking conditions are: temperature 250-320℃, time 10-30min.

10. An enamel coating, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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