A blasting-free ceramic coating, a preparation method and a spraying method thereof

Abstract

The application provides a sand-free ceramic coating and a preparation and spraying method thereof, which is composed of a binder, a ceramic filler, a color paste, a functional additive and a diluent, wherein the ceramic filler comprises silicon carbide, sodium pyrithione and silicon dioxide powder. By optimizing the composition of the ceramic filler, the formula of the binder and the spraying process parameters, the dependence of the ceramic coating on the sand blasting treatment of the base material is reduced. Through the synergistic effect of the ceramic filler and the curing treatment of the binder, a double bonding mechanism of physical anchoring and chemical bonding is constructed on the surface of the base material, the connection strength of the ceramic coating with the base material is effectively improved, the surface of the base material does not need to be sand blasted, the spraying efficiency of the ceramic coating is greatly improved, the curing time of the ceramic coating is significantly shortened by optimizing the spraying process parameters, thereby the input cost of the spraying process is reduced, the ceramic coating is not limited by the surface condition of the base material, has the advantages of strong adhesion, long service life, stable mechanical property and easy popularization and implementation.

Description

Technical Field

[0001] This application belongs to the field of coating technology, specifically relating to a sandblast-free ceramic coating and its preparation and spraying methods. Background Technology

[0002] In existing technologies, ceramic coatings play a crucial role in the construction, industrial, home appliance, and decorative fields. They offer excellent corrosion resistance, high-temperature resistance, and decorative properties, and are widely used for surface protection of substrates such as metals and concrete. They are a good coating choice for household (mainly kitchenware), industrial, and small household appliances. However, current ceramic coatings on the market face some technical bottlenecks in their application, particularly in surface pretreatment and application efficiency.

[0003] In existing technologies, traditional ceramic coating application typically requires sandblasting of the substrate to remove surface oxide layers, dirt, and grease, thereby improving coating adhesion. While sandblasting effectively enhances coating bonding strength, the process is complex and costly, generating significant amounts of dust and noise, negatively impacting the environment and the health of construction workers. Furthermore, sandblasting demands a high degree of surface smoothness from the substrate; minor defects or irregular shapes can lead to uneven coating adhesion, ultimately affecting the overall performance of the coating.

[0004] In recent years, although some sandblasting-free coating technologies have been developed, these coatings still have many problems in practical applications. For example, some sandblasting-free coatings have insufficient adhesion, especially on damp or complex substrates, and are prone to peeling; while other sandblasting-free coatings have improved adhesion, their corrosion resistance and high-temperature resistance are poor, making them unable to meet the long-term use requirements of industrial and construction fields. In addition, the existing application process for sandblasting-free coatings is still relatively cumbersome, requiring multiple coats and curing, resulting in low construction efficiency and making it difficult to adapt to large-scale industrial applications.

[0005] Therefore, in order to solve the problem of existing ceramic coatings relying on sandblasting during construction, and at the same time improve the overall performance and construction efficiency of the coatings, there is an urgent need to develop a sandblast-free ceramic coating to meet the needs of modern industry and construction for efficient, environmentally friendly, and high-performance coatings. Summary of the Invention

[0006] This application aims to address the technical problems in the prior art, such as the limited adhesion performance between traditional ceramic coatings and substrates, the need for sandblasting of the substrate before spraying, which increases the number of steps, reduces the spraying efficiency of ceramic coatings, increases labor and material costs, imposes strict requirements on the surface roughness of the substrate, and results in large fluctuations in spraying quality. Therefore, this application proposes a sandblast-free ceramic coating.

[0007] In order to solve the technical problems raised in this application, this application also provides a method for preparing a sandblasting-free ceramic coating;

[0008] In order to solve the technical problems raised in this application, this application also provides a method for spraying a sandblast-free ceramic coating.

[0009] This application adopts the following scheme: a sandblast-free ceramic coating, which is composed of the following components by weight:

[0010] 45-55 parts adhesive

[0011] 10-15 parts ceramic filler

[0012] 20-25 parts color paste

[0013] Functional additives 1-5 parts

[0014] 8-12 parts diluent;

[0015] The ceramic filler includes silicon carbide, sodium pyrithione, and silica powder.

[0016] The mass ratio of silicon carbide, sodium pyrithione, and silicon dioxide powder is (0.8-1.3):1:1.

[0017] In some possible embodiments,

[0018] The particle size range of the silicon carbide is 35μm-45μm;

[0019] The particle size range of the sodium pyrithione is 20μm-30μm;

[0020] The particle size range of the silica powder is 15μm-20μm.

[0021] In some possible embodiments,

[0022] The adhesive includes polymethylpolysiloxane and silica sol;

[0023] The mass ratio of the polymethylpolysiloxane to the silica sol is (2.2-3.5):1.

[0024] In some possible embodiments,

[0025] The functional additives include propylene glycol methyl ether and silicone oil;

[0026] The mass ratio of the propylene glycol methyl ether to the silicone oil is (0.8-1):1.

[0027] In some possible embodiments,

[0028] The diluents include isopropanol, cyclohexanone, and ethylene glycol ethyl ether;

[0029] The mass ratio of isopropanol, cyclohexanone, and ethylene glycol ethyl ether is (5.5-6.2):1:1.

[0030] To address the technical problems raised in this application, this application also provides a method for preparing a sandblast-free ceramic coating, comprising the following steps:

[0031] Step 101. Primer Preparation

[0032] According to the preset target ratio, the binder, ceramic filler, primer pigment, functional additives and diluent are put into the high-speed disperser in sequence and dispersed for 15min-20min at 800rpm-1200rpm and 25℃-40℃ to obtain the primer.

[0033] Step 102. Topcoat Preparation

[0034] According to the preset target ratio, the binder, ceramic filler, topcoat color paste, functional additives and diluent are sequentially added into the high-speed disperser and dispersed for 15min-20min at 800rpm-1200rpm and 25℃-40℃ to obtain the topcoat.

[0035] In some feasible embodiments, the adhesive is cured in both steps 101 and 102;

[0036] The aging process includes the following steps:

[0037] Step 201: According to the preset target ratio, polymethylpolysiloxane and silica sol are sequentially added to the curing tank. After curing at room temperature for 4-6 hours at a rolling speed of 120-150 rpm, the cured adhesive is obtained.

[0038] In some feasible embodiments, the color paste undergoes a curing treatment, which includes the following steps:

[0039] Add the color paste and an appropriate amount of binder into the curing tank in sequence, and cure for 30-60 minutes at room temperature with a rolling speed of 80-100 rpm to obtain the cured color paste.

[0040] In practice, by curing the adhesive, the molecular chains within it will have sufficient time and energy to move and recombine. Under baking conditions, the silicon-oxygen bonds (Si-O) in the polymethylpolysiloxane molecules can undergo a cross-linking reaction. This facilitates the formation of a three-dimensional network structure on the substrate, significantly improving the mechanical strength of the coating film.

[0041] To address the technical problems raised in this application, this application also provides a method for spraying a sandblast-free ceramic coating, comprising the following steps:

[0042] Step 301. Preheating

[0043] Preheat the substrate to 45℃-60℃;

[0044] Step 302. Primer spraying

[0045] Spray the prepared primer onto the preheated substrate from step 301;

[0046] Step 303. Topcoat Spraying

[0047] Spray the prepared topcoat directly onto the primer sprayed in step 302;

[0048] Step 304. Baking

[0049] After spraying in steps 302 and 303, the substrate is transferred to a baking oven and baked at 80℃-280℃ for 15-20 minutes to complete the spraying of a sandblast-free ceramic coating.

[0050] In some feasible embodiments, the primer is sprayed to a thickness of 25μm-35μm, and the topcoat is sprayed to a thickness of 5μm-15μm.

[0051] In some feasible embodiments, step 304 includes a heating and baking section, a heat preservation and baking section, and a cooling section performed sequentially in time.

[0052] The heating and baking section heats the coated substrate to 280°C at a heating rate of 40°C / min-50°C / min.

[0053] The heat preservation and baking section involves keeping the substrate at 280℃ for 10-20 minutes.

[0054] The cooling section involves cooling the substrate from 280°C to room temperature under natural conditions.

[0055] Compared with the prior art, this application has the following beneficial effects:

[0056] This application provides a sandblast-free ceramic coating and its preparation and spraying method, which consists of a binder, ceramic filler, colorant, functional additives, and diluent. The ceramic filler includes silicon carbide, sodium pyrithione, and silica powder. By optimizing the composition of the ceramic filler, the binder formulation, and the spraying process parameters, the dependence of the ceramic coating on substrate sandblasting is reduced. Through the synergistic effect of the ceramic filler and the curing treatment of the binder, a dual bonding mechanism of physical anchoring and chemical bonding is constructed on the substrate surface, effectively improving the connection strength between the ceramic coating and the substrate. Sandblasting of the substrate surface is unnecessary, greatly improving the spraying efficiency of the ceramic coating. Optimizing the spraying process parameters significantly shortens the curing time of the ceramic coating, thereby reducing the investment cost of the spraying process. It is not limited by the surface condition of the substrate and has the advantages of strong adhesion, long service life, stable mechanical properties, and ease of promotion and implementation. Detailed Implementation

[0057] The technical solutions provided in this application will be further described with reference to the specific embodiments shown in the figures. Example 1

[0058] (1) A method for preparing a sandblast-free ceramic coating includes the following steps:

[0059] Step 101. Primer Preparation

[0060] According to the component list shown in Table 1, the binder, ceramic filler, primer pigment, functional additives and diluent are sequentially added into a high-speed disperser and dispersed at 800 rpm and 25°C for 15 minutes to obtain the primer.

[0061] Step 102. Topcoat Preparation

[0062] According to the component list shown in Table 1, the binder, ceramic filler, topcoat color paste, functional additives and diluent are sequentially added into a high-speed disperser and dispersed for 15 minutes at 800 rpm and 25℃-40℃ to obtain the topcoat.

[0063] In steps 101 and 102, the binder and pigment undergo a curing treatment, which includes the following steps:

[0064] Step 201. According to the component table shown in Table 1, add polymethylpolysiloxane and silica to a high-speed disperser and disperse for 10 minutes at room temperature and 500 rpm to obtain the binder to be cured.

[0065] Step 202. Divide the adhesive to be cured obtained in step 201 into two portions, put one portion into a curing tank, and cure it for 4 hours at room temperature with a rolling speed of 120 rpm to obtain the cured adhesive.

[0066] Step 203. Add another portion of the binder to be cured and the primer color paste (or topcoat color paste) into the curing tank in sequence. After curing for 30 minutes at room temperature with a roller speed of 80 rpm, the cured color paste is obtained.

[0067] (2) A method for spraying a sandblast-free ceramic coating includes the following steps:

[0068] Step 301. Preheating

[0069] Preheat the substrate to 45°C;

[0070] Step 302. Primer spraying

[0071] The prepared primer is sprayed onto the preheated substrate in step 301, and the primer spraying thickness is 25μm.

[0072] Step 303. Topcoat Spraying

[0073] The prepared topcoat is directly sprayed onto the primer sprayed in step 302, and the topcoat thickness is 5μm.

[0074] Step 304. Baking

[0075] The substrate after spraying in steps 302 and 303 is transferred to the baking oven and baked in sequence, including the heating baking section, the heat preservation baking section and the cooling section.

[0076] The heating and baking section heats the coated substrate to 280°C at a heating rate of 40°C / min.

[0077] The heat preservation and baking section involves keeping the substrate at 280℃ for 10 minutes;

[0078] The cooling section involves cooling the substrate from 280°C to room temperature under natural conditions.

[0079] In steps 302 and 303, when spraying the primer or topcoat, the nozzle diameter of the spray gun is 1.0 mm, the spraying pressure is 0.2 MPa, the distance between the spray gun and the substrate is 25 cm, and the prepared primer or topcoat is filtered through a 150-mesh filter before spraying. Example 2

[0080] (1) A method for preparing a sandblast-free ceramic coating includes the following steps:

[0081] Step 101. Primer Preparation

[0082] According to the component list shown in Table 1, the binder, ceramic filler, primer pigment, functional additives and diluent are sequentially added into a high-speed disperser and dispersed at 1000 rpm and 30°C for 18 minutes to obtain the primer.

[0083] Step 102. Topcoat Preparation

[0084] According to the component list shown in Table 1, the binder, ceramic filler, topcoat color paste, functional additives and diluent are sequentially added into a high-speed disperser and dispersed at 1000 rpm and 30℃ for 18 minutes to obtain the topcoat.

[0085] The binder and colorant undergo a curing process, which includes the following steps:

[0086] Step 201. According to the component table shown in Table 1, add polymethylpolysiloxane and silica to a high-speed disperser and disperse for 10 minutes at room temperature and 650 rpm to obtain the binder to be cured.

[0087] Step 202. Divide the adhesive to be cured obtained in step 201 into two portions, put one portion into a curing tank, and cure it for 5 hours at room temperature with a rolling speed of 130 rpm to obtain the cured adhesive.

[0088] Step 203. Add another portion of the binder to be cured and the primer color paste (or topcoat color paste) into the curing tank in sequence. After curing for 45 minutes at room temperature with a roller speed of 90 rpm, the cured color paste is obtained.

[0089] (2) A method for spraying a sandblast-free ceramic coating includes the following steps:

[0090] Step 301. Preheating

[0091] Preheat the substrate to 50°C;

[0092] Step 302. Primer spraying

[0093] The prepared primer is sprayed onto the preheated substrate in step 301, and the primer spraying thickness is 30μm.

[0094] Step 303. Topcoat Spraying

[0095] The prepared topcoat is directly sprayed onto the primer sprayed in step 302, and the topcoat thickness is 10μm.

[0096] Step 304. Baking

[0097] The substrate after spraying in steps 302 and 303 is transferred to the baking oven and baked in sequence, including the heating baking section, the heat preservation baking section and the cooling section.

[0098] The heating and baking section heats the coated substrate to 280°C at a heating rate of 45°C / min.

[0099] The heat preservation and baking section involves keeping the substrate at 280℃ for 15 minutes.

[0100] The cooling section involves cooling the substrate from 280°C to room temperature under natural conditions.

[0101] In steps 302 and 303, when spraying the primer or topcoat, the nozzle diameter of the spray gun is 1.5mm, the spraying pressure is 0.34MPa, the distance between the spray gun and the substrate is 35cm, and the prepared primer or topcoat is filtered through a 175-mesh filter before spraying. Example 3

[0102] (1) A method for preparing a sandblast-free ceramic coating includes the following steps:

[0103] Step 101. Primer Preparation

[0104] According to the component list shown in Table 1, the binder, ceramic filler, primer pigment, functional additives and diluent are sequentially added into a high-speed disperser and dispersed at 1200 rpm and 40℃ for 20 minutes to obtain the primer.

[0105] Step 102. Topcoat Preparation

[0106] According to the component list shown in Table 1, the binder, ceramic filler, topcoat color paste, functional additives and diluent are sequentially added into a high-speed disperser and dispersed at 1200 rpm and 40℃ for 20 minutes to obtain the topcoat.

[0107] The binder and colorant undergo a curing process, which includes the following steps:

[0108] Step 201. According to the component table shown in Table 1, add polymethylpolysiloxane and silica to a high-speed disperser and disperse for 10 minutes at room temperature and 800 rpm to obtain the binder to be cured.

[0109] Step 202. Divide the adhesive to be cured obtained in step 201 into two portions, put one portion into a curing tank, and cure it for 6 hours at room temperature with a rolling speed of 150 rpm to obtain the cured adhesive.

[0110] Step 203. Add another portion of the binder to be cured and the primer color paste (or topcoat color paste) into the curing tank in sequence. After curing for 60 minutes at room temperature with a rolling speed of 100 rpm, the cured color paste is obtained.

[0111] (2) A method for spraying a sandblast-free ceramic coating includes the following steps:

[0112] Step 301. Preheating

[0113] Preheat the substrate to 60°C;

[0114] Step 302. Primer spraying

[0115] The prepared primer is sprayed onto the preheated substrate in step 301, and the primer coating thickness is 35μm.

[0116] Step 303. Topcoat Spraying

[0117] The prepared topcoat is directly sprayed onto the primer sprayed in step 302, and the topcoat thickness is 15μm.

[0118] Step 304. Baking

[0119] The substrate after spraying in steps 302 and 303 is transferred to the baking oven and baked in sequence, including the heating baking section, the heat preservation baking section and the cooling section.

[0120] The heating and baking section heats the coated substrate to 280°C at a heating rate of 50°C / min.

[0121] The heat preservation and baking section involves keeping the substrate at 280℃ for 20 minutes;

[0122] The cooling section involves cooling the substrate from 280°C to room temperature under natural conditions.

[0123] In steps 302 and 303, when spraying the primer or topcoat, the nozzle diameter of the spray gun is 1.5mm, the spraying pressure is 0.4MPa, the distance between the spray gun and the substrate is 50cm, and the prepared primer or topcoat is filtered through a 200-mesh filter before spraying.

[0124] Table 1 Component Parameter Table for Examples 1-3

[0125]

[0126] The sandblast-free ceramic coatings prepared in Examples 1-3 were subjected to the following tests:

[0127] Test 1: Measure the total thickness of the paint film using a paint film thickness tester;

[0128] Test 2: Measure the gloss of the paint film using a gloss meter;

[0129] Test 3: Measure the pencil hardness of the paint film according to GB / T 6739-2006;

[0130] Test 4: Measure the paint film adhesion rating according to GB / T 1720-2020;

[0131] Test 5: Using a 3M 744C scouring pad, the paint film was rubbed under a load of 4.5kg. The number of rubs required to produce scratches was recorded to test the abrasion resistance of the paint film.

[0132] Test 6: The substrate with the coating was immersed in 80°C salt water (2% NaCl) for 24 hours. After immersion, the substrate was removed and the coating was checked to test the salt water resistance of the coating.

[0133] Test 7: The substrate with the coating was immersed in glacial acetic acid (5%) and boiled continuously for 24 hours. After the immersion was completed, the substrate was removed and the coating adhesion was checked to test the coating's resistance to glacial acetic acid.

[0134] Test 8: The ceramic coating prepared in Examples 1-3 was applied to the test pan, and an egg was fried in the pan without oil. If the egg did not stick at all, the non-stick level was Grade I; if it stuck slightly, the non-stick level was Grade II; and if it stuck severely, the non-stick level was Grade III. The test results are shown in Table 2 below.

[0135] During the testing process, the ceramic coatings prepared in Examples 1-3 were all sprayed onto aluminum alloy substrates of the same specifications.

[0136] Table 2 Test Results of Examples 1-3

[0137] Test Project Example 1 Example 2 Example 3 Total paint film thickness (μm) 30 40 50 Glossiness (°) 49 54 47 Pencil hardness 9H 10H 9H Adhesion (Grade) 0 0 1 Abrasion resistance (times) 3280 3411 3266 Salt water resistant (2% NaCl) No abnormalities No abnormalities No abnormalities Glacial acetic acid resistant (5%) No abnormalities No abnormalities No abnormalities Non-stick (for oil-free fried eggs) Level I Level I Level I

[0138] As shown in Table 2, the total thickness of the paint film obtained in Examples 1-3 is within the range of 30μm-50μm. By controlling the overall thickness of the paint film, its protective performance on the substrate can be guaranteed, as well as the bonding performance between the paint film and the substrate, thereby reducing paint consumption and controlling production costs.

[0139] The paint film prepared in Examples 1-3 has an average pencil hardness of up to 9H and excellent surface properties. It can be used to prepare high-end cookware. Conventional kitchen utensils (spatulas, chopsticks, spoons) cannot damage the paint film.

[0140] The paint films prepared in Examples 1-3 exhibit excellent bonding performance with the substrate. They show excellent performance in cross-cut test without substrate sandblasting. By designing the binder ratio and curing the binder and color paste before preparing the primer and topcoat, the paint film and substrate are tightly bonded by chemical bonds, effectively improving interfacial adhesion. During the coating process, the substrate sandblasting step can be omitted, reducing the dependence of ceramic coatings on substrate sandblasting and greatly improving the coating efficiency.

[0141] The paint films prepared in Examples 1-3 exhibit excellent wear resistance, salt spray resistance, and acid resistance, demonstrating excellent non-stick properties. They are suitable for kitchen use and can be used to prepare high-end cookware. Through the design of the binder and the combination of multi-level ceramic fillers, the paint film and the substrate are tightly connected by chemical bonds, effectively improving the interfacial adhesion. During the coating process, the substrate sandblasting step can be omitted, reducing the dependence of ceramic coatings on substrate sandblasting and greatly improving the coating efficiency.

[0142] This application provides a sandblast-free ceramic coating and its preparation and spraying method, which consists of a binder, ceramic filler, colorant, functional additives, and diluent. The ceramic filler includes silicon carbide, sodium pyrithione, and silica powder. By optimizing the composition of the ceramic filler, the binder formulation, and the spraying process parameters, the dependence of the ceramic coating on substrate sandblasting is reduced. Through the synergistic effect of the ceramic filler and the curing treatment of the binder, a dual bonding mechanism of physical anchoring and chemical bonding is constructed on the substrate surface, effectively improving the connection strength between the ceramic coating and the substrate. Sandblasting of the substrate surface is unnecessary, greatly improving the spraying efficiency of the ceramic coating. Optimizing the spraying process parameters significantly shortens the curing time of the ceramic coating, thereby reducing the investment cost of the spraying process. It is not limited by the surface condition of the substrate and has the advantages of strong adhesion, long service life, stable mechanical properties, and ease of promotion and implementation.

[0143] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A sandblast-free ceramic coating, characterized in that, It consists of the following components by weight: 45-55 parts binder, 10-15 parts ceramic filler, 20-25 parts color paste, 1-5 parts functional additives, and 8-12 parts diluent. The ceramic filler includes silicon carbide, sodium pyrithione, and silica powder. The mass ratio of the silicon carbide, sodium pyrithione, and silicon dioxide powder is (0.8-1.3):1:

1. The particle size range of the silicon carbide is 35μm-45μm; The particle size range of the sodium pyrithione is 20μm-30μm; The particle size range of the silica powder is 15μm-20μm; The adhesive is composed of polymethylpolysiloxane and silica sol; The mass ratio of the polymethylpolysiloxane to the silica sol is (2.2-3.5):1; The functional additives include propylene glycol methyl ether and silicone oil; The mass ratio of the propylene glycol methyl ether to the silicone oil is (0.8-1):1; The diluents include isopropanol, cyclohexanone, and ethylene glycol ethyl ether; The mass ratio of isopropanol, cyclohexanone, and ethylene glycol ethyl ether is (5.5-6.2):1:

1.

2. The method for preparing a sandblast-free ceramic coating according to claim 1, characterized in that, Includes the following steps: Step 101. Primer Preparation According to the preset target ratio, the binder, ceramic filler, primer pigment, functional additives and diluent are put into the high-speed disperser in sequence and dispersed for 15min-20min at 800rpm-1200rpm and 25℃-40℃ to obtain the primer. Step 102. Topcoat Preparation According to the preset target ratio, the binder, ceramic filler, topcoat color paste, functional additives and diluent are sequentially added into the high-speed disperser and dispersed for 15min-20min at 800rpm-1200rpm and 25℃-40℃ to obtain the topcoat.

3. The method for preparing a sandblast-free ceramic coating according to claim 2, characterized in that, In steps 101 and 102, the adhesive undergoes a curing treatment. The aging process includes the following steps: Step 201: According to the preset target ratio, polymethylpolysiloxane and silica sol are sequentially added to the curing tank. After curing at room temperature for 4-6 hours at a rolling speed of 120-150 rpm, the cured adhesive is obtained.

4. A spraying method for the coating prepared by the method for preparing a sandblast-free ceramic coating according to claim 2, characterized in that, Includes the following steps: Step 301. Preheating Preheat the substrate to 45℃-60℃; Step 302. Primer spraying Spray the prepared primer onto the preheated substrate from step 301; Step 303. Topcoat Spraying Spray the prepared topcoat directly onto the primer sprayed in step 302; Step 304. Baking After spraying in steps 302 and 303, the substrate is transferred to a baking oven and baked at 80℃-280℃ for 15-20 minutes to complete the spraying of a sandblast-free ceramic coating.

5. A spraying method for the coating prepared by the method for preparing a sandblast-free ceramic coating according to claim 4, characterized in that, The thickness of the primer spray is 25μm-35μm; the thickness of the topcoat spray is 5μm-15μm.

6. A spraying method for the coating prepared by the method for preparing a sandblast-free ceramic coating according to claim 4, characterized in that, Step 304 includes a heating and baking section, a heat preservation and baking section, and a cooling section, which are carried out sequentially in time. The heating and baking section heats the coated substrate to 280°C at a heating rate of 40°C / min-50°C / min. The heat preservation and baking section involves keeping the substrate at 280℃ for 10-20 minutes; the cooling section involves cooling the substrate from 280℃ to room temperature under natural conditions.

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