Preparation method of double-silicon modified phosphate high-temperature coating

Abstract

A preparation method of a double-silicon modified phosphate high-temperature coating is characterized by comprising the following steps: (1) dissolving phosphate in a solvent, magnetically stirring, slowly adding silicon resin, adding a silane coupling agent and a neutral catalyst, and magnetically stirring to obtain modified phosphate; (2) pouring modified phosphate obtained by modification into a container, magnetically stirring, repeatedly vacuumizing, and adding silica sol and an inorganic curing agent under the protection of an inert gas atmosphere; and (3) taking out, directly adding a defoaming agent, carrying out magnetic stirring and ultrasonic treatment, taking out, curtain-coating on a glass substrate, and curing. Phosphate is modified by silica sol and silicon resin, so that the flexibility, the heat insulation property, the flame retardance and the high-temperature resistance of the coating are enhanced.

Description

Technical Field

[0001] The invention relates to a method for preparing a coating, which is applied to the surface of components of household appliances. Background Art

[0002] With rising consumption and health awareness, existing home appliance coating technologies are struggling to meet the market's dual demands for safety and overall quality. A special testing report indicates that trace amounts of perfluorooctanoic acid (PFOA) residues were detected in the Teflon coating of several mainstream air fryer models when simulating high-temperature frying or grilling conditions above 230°C. This bioaccumulative, persistent organic pollutant poses a migration risk under long-term high-temperature conditions, posing a potential threat to consumer health.

[0003] Traditional coating technologies also exhibit multiple flaws in core kitchen appliance components. Range hood systems are constantly exposed to oily fumes, posing three challenges to existing coating systems: increased cleaning frequency due to oily adhesion, accelerated coating aging and shedding under high temperatures, and a precipitous decline in overall protective performance over the lifespan. The burners and panels of stoves are subject to direct exposure to open flames and periodic thermal shock. Conventional organic coatings are susceptible to irreversible discoloration and blistering under sustained high temperatures, affecting both aesthetics and protective performance. In extreme cases, these coatings can even cause malfunctions.

[0004] The contradictions in coating technology for air conditioning heat exchange systems are even more prominent. As a core heat exchange component, the fin surface treatment technology directly affects the energy efficiency and service life of the entire machine. Although the current mainstream hydrophilic coating can effectively solve the problem of condensed water freezing by reducing the contact angle of water droplets (usually <15°), it sacrifices the necessary corrosion resistance and significantly reduces its service life in coastal areas with high salt fog. Although the coating system that focuses on anti-corrosion protection can withstand harsh environments such as salt fog and acid rain, it sacrifices heat exchange efficiency, resulting in a 5% to 8% decrease in the energy efficiency ratio (EER) of the air conditioning system, which forms a structural contradiction with the industry's trend of energy conservation and emission reduction.

[0005] The industry faces four key bottlenecks in coating technology: Teflon systems must balance high-temperature stability with hazardous substance control; hydrophilic coatings must maintain wettability while improving corrosion resistance; ceramic coatings must overcome cost and process bottlenecks to mitigate brittle cracking; and traditional organic coatings must overcome technical challenges in oil and dirt adhesion resistance and high-temperature stability. The market urgently needs a new coating solution that achieves a multi-dimensional performance balance in operating temperatures below 400°C. This technology must simultaneously meet food-safe material standards, long-term weather resistance, self-cleaning capabilities, and excellent thermal stability to support the transformation and upgrading of home appliances towards high-end, healthier designs. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing an environmentally friendly and high-temperature resistant double silicon modified phosphate high-temperature coating in response to the above-mentioned technical status quo.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a method for preparing a double silicon modified phosphate high temperature coating, characterized by comprising the following steps:

[0008] ① Dissolve 80-100 parts of phosphate in a solvent, stir magnetically, slowly add 10-20 parts of silicone resin, heat to 60-80°C, add 0.5-1 parts of silane coupling agent and 1-3 parts of neutral catalyst, stir magnetically to obtain modified phosphate;

[0009] ② Take 40-50 parts of the modified phosphate, pour it into a container, stir it magnetically at 50-80°C, repeatedly evacuate, and under the protection of an inert gas (such as nitrogen), add 5-10 parts of silica sol and 0.5-1 part of an inorganic curing agent;

[0010] ③ After taking it out, directly add 0.5-1 parts of defoaming agent, stir magnetically at 30-40℃, ultrasonicate, take it out and spray it on the glass substrate to solidify;

[0011] The above parts are all weight ratios.

[0012] Preferably, the phosphate is at least one of aluminum phosphate, aluminum dihydrogen phosphate, and aluminum hypophosphite.

[0013] Preferably, the solvent is at least one of ethanol and water.

[0014] Preferably, the silicone resin is at least one of amino silicone resin, methyl silicone resin and phenyl silicone resin.

[0015] Preferably, the silane coupling agent is at least one of KH550, KH560, and KH570.

[0016] Preferably, the neutral catalyst is at least one of dibutyltin dilaurate and stannous octoate borate.

[0017] Preferably, the inorganic curing agent is at least one of iron oxide Fe2O3, magnesium oxide MgO, aluminum oxide Al2O3 and zinc oxide ZnO.

[0018] Preferably, the particle size of the silica sol is 1 to 15 nm.

[0019] Preferably, the defoaming agent is at least one of BYK-024, DF-6900, Foamex 810, and EFKA-2044.

[0020] Preferably, the ultrasonic time in step ③ is 10 to 20 minutes.

[0021] Preferably, the curing in step ③ is divided into three stages in sequence, and the curing temperature of each stage is 60-80°C; 140-160°C; 200-220°C.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] Phosphate is selected as the main film-forming substance, and an interpenetrating network structure of inorganic phase (Si-O-Si) and organic phase (Si-OR) is formed by compounding silica sol (such as SiO2 nanoparticles) with silicone resin. The density and cross-linking degree of the coating are significantly improved, thereby enhancing wear resistance and hardness. Silicone resin modified systems (such as methyl silicone resin) can be cured at room temperature or low temperature (80-150°C) by introducing organic groups (such as -CH3), avoiding the energy consumption problem of traditional phosphate coatings that require high-temperature curing above 300°C. The silica sol nanoparticles in the silica sol modified system fill the micropores of the phosphate coating, forming a dense layer, and the adhesion is improved by 20%-30%. Water-based coatings compounded with modified silica sol and silicone resin (such as silica sol-silicone resin high-temperature coatings) do not contain organic solvents and comply with environmental regulations. At the same time, self-crosslinking is achieved through hydroxyl reactions, reducing the amount of curing agent used.

[0024] Phosphate coating uses [-Al-OP-] as the main film-forming chain. Through the modification of silica sol, the silanol (-Si-OH) in the silica sol and the Al in the phosphate 3+ PO3 - They are combined through hydrogen bonds and chemical bonds to form a Si-O-Al-P cross-linked structure, which enhances low-temperature curing performance and reduces porosity.

[0025] The Si-O-Si main chain of silicone resin forms a Si-O-Al-P covalent bond with the Al-OP chain of phosphate. At the same time, organic groups (such as -CH3) are interspersed in the inorganic network. Above 500°C, silicone resin is carbonized to form SiO2, which forms a composite ceramic structure with aluminum phosphate to reduce high-temperature brittleness.

[0026] By modifying phosphate with silica sol and silicone resin, the coating's flexibility, thermal insulation, flame retardancy, and high-temperature resistance are enhanced, significantly improving the service life and performance stability of various household appliances in environments below 400°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the water vapor corrosion device.

[0028] Figure 2 This is the SEM image of the surface morphology of Example 2 after curing.

[0029] Figure 3 This is the SEM image of the surface morphology of Comparative Example 4 after curing.

[0030] Figure 4 This is a graph showing the mass change of the phosphate coating samples in Examples 1-3 after being corroded in a 650°C high-temperature salt-water vapor environment for 100 hours.

[0031] Figure 5 This is a graph showing the mass change of the phosphate-coated samples in Comparative Examples 1-4 after being corroded in a 650°C high-temperature salt-water vapor environment for 100 hours. DETAILED DESCRIPTION

[0032] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] (1) Dissolve 80 parts of aluminum phosphate AlPO4 in 100 parts of ethanol and stir magnetically at 30°C for 15 minutes.

[0035] (2) Slowly add 10 parts of amino silicone resin, raise the temperature to 60°C, add 0.5 parts of silane coupling agent KH550 and 1 part of neutral catalyst dibutyltin dilaurate, and stir magnetically for 2 hours to obtain modified Si-P.

[0036] (3) Take 40 parts of modified Si-P, pour them into a three-necked flask, stir magnetically at 50°C, repeatedly evacuate, and under the protection of nitrogen atmosphere, slowly add 5 parts of silica sol with a particle size of 5 nm in three times, and add 0.5% of inorganic curing agent iron oxide Fe2O3.

[0037] (4) Take it out and pour it into a beaker, directly add 0.5 parts of defoaming agent BYK-024, stir magnetically at 30℃ for 15 minutes, ultrasonicate for 10 minutes, take it out and spray it on the glass substrate, and cure it in three stages at temperatures of 60, 140 and 200℃ respectively.

[0038] Example 2

[0039] (1) Dissolve 90 parts of aluminum dihydrogen phosphate Al(H2PO4)3 in 110 parts of deionized water and stir magnetically at 40°C for 15 minutes.

[0040] (2) Slowly add 15 parts of methyl silicone resin, raise the temperature to 70°C, add 0.75 parts of silane coupling agent KH560 and 2 parts of neutral catalyst dibutyltin dilaurate, and stir magnetically for 3 hours to obtain modified Si-P.

[0041] (3) Take 45 parts of modified Si-P, pour them into a three-necked flask, stir magnetically at 60°C, repeatedly evacuate, and under the protection of nitrogen atmosphere, slowly add 5 parts of silica sol with a particle size of 10 nm in three times and add 0.75 parts of inorganic curing agent magnesium oxide MgO.

[0042] (4) Take it out and pour it into a beaker, directly add 0.5 parts of defoaming agent DF-6900, stir magnetically at 35℃ for 15 minutes, ultrasonicate for 15 minutes, take it out and spray it on the glass substrate, and the curing temperatures in three stages are 70, 150 and 210℃ respectively.

[0043] Example 3

[0044] (1) Dissolve 100 parts of aluminum dihydrogen phosphate (Al(H2PO4)3) in a 1:1 mixture of 120 parts of ethanol and deionized water, and stir magnetically at 50°C for 17 minutes.

[0045] (2) Slowly add 20 parts of phenyl silicone resin, raise the temperature to 80°C, add 1 part of silane coupling agent KH570 and 3 parts of neutral catalyst stannous octoate borate, and stir magnetically for 4 hours to obtain modified Si-P.

[0046] (3) Take 50 parts of modified Si-P, pour them into a three-necked flask, stir magnetically at 80°C, repeatedly evacuate, and under the protection of nitrogen atmosphere, slowly add 5 parts of silica sol with a particle size of 15 nm in three times and add 1 part of inorganic curing agent zinc oxide ZnO.

[0047] (4) Take it out and pour it into a beaker, directly add 1 part of defoaming agent Foamex 810, stir magnetically at 40℃ for 15 minutes, ultrasonicate for 20 minutes, take it out and spray it on the glass substrate, and cure it in three stages at temperatures of 80, 160 and 220℃ respectively.

[0048] Comparative Example 1: Mixed phosphate disilicon modified phosphate

[0049] (1) Take 85 parts of aluminum phosphate AlPO4 and aluminum dihydrogen phosphate Al(H2PO4)3 and dissolve them in 115 parts of deionized water. Stir magnetically at 35°C for 18 minutes.

[0050] (2) Slowly add 14 parts of amino silicone resin, raise the temperature to 65°C, add 0.6 parts of silane coupling agents KH560 and KH570, and 1 part of neutral catalyst stannous octoate borate, and stir magnetically for 2.5 hours to obtain modified Si-P.

[0051] (3) Take 42 parts of modified Si-P, pour them into a three-necked flask, stir magnetically at 65°C, repeatedly evacuate, and under the protection of nitrogen atmosphere, slowly add 5 parts of silica sol with a particle size of 8 nm in three times and add 0.7 parts of inorganic alumina Al2O3.

[0052] (4) Pour the mixture into a beaker and directly add 0.7 parts of defoaming agent Foamex 810. Stir magnetically at 34°C for 15 minutes and ultrasonicate for 12 minutes. Then, pour the mixture onto a glass substrate and cure it in three stages at temperatures of 65, 145, and 205°C.

[0053] Comparative Example 2 Silicone resin modified phosphate

[0054] (1) Dissolve 85 parts of aluminum dihydrogen phosphate (Al(H2PO4)3) in 100 parts of deionized water and stir magnetically at 35°C for 15 minutes.

[0055] (2) Slowly add 16 parts of methyl silicone resin, raise the temperature to 65°C, add 0.6 parts of silane coupling agents KH560 and KH570, and 1 part of neutral dibutyltin dilaurate, and stir magnetically for 2.5 hours to obtain modified Si-P.

[0056] (3) Take 43 parts of modified Si-P, pour it into a three-necked flask, stir it magnetically at 65°C, repeatedly evacuate, and add 0.7 parts of inorganic alumina Al2O3 under the protection of nitrogen atmosphere.

[0057] (4) Pour the mixture into a beaker and directly add 0.8 parts of defoaming agent Foamex 810. Stir magnetically at 36°C for 15 minutes and ultrasonicate for 15 minutes. Then, pour the mixture onto a glass substrate and cure it in three stages at temperatures of 70, 150, and 210°C.

[0058] Comparative Example 3 Silicon solvent modified zero acid salt

[0059] (1) Dissolve 95 parts of aluminum hypophosphite Al(PO2H2)3 in 110 parts of deionized water and stir under magnetic stirring at 45°C for 20 minutes.

[0060] (2) The temperature was raised to 75°C, 0.8 parts of silane coupling agents KH550 and KH570 and 1 part of neutral dibutyltin dilaurate were added, and magnetic stirring was performed for 3.5 hours.

[0061] (3) 46 parts of the modified varnish were poured into a three-necked flask, stirred magnetically at 75°C, and repeatedly vacuumed. Under the protection of a nitrogen atmosphere, 5 parts of silica sol with a particle size of 10 nm and 0.9 parts of magnesium oxide (MgO) were slowly added.

[0062] (4) Take it out and pour it into a beaker, directly add 0.8 parts of defoaming agent BYK-024 and DF-6900, stir magnetically at 33℃ for 15 minutes, ultrasonicate for 20 minutes, take it out and coat it on the glass substrate, and cure it in three stages at temperatures of 75, 155, and 215℃ respectively.

[0063] Comparative Example 4 Phosphate varnish coating

[0064] (1) Dissolve 100 parts of aluminum hypophosphite Al(PO2H2)3 in 105 parts of ethanol and stir magnetically at 50°C for 15 minutes.

[0065] (2) Raise the temperature to 75°C, add 1 part of silane coupling agent KH560 and 1 part of neutral dibutyltin dilaurate, and stir magnetically for 4 hours.

[0066] (3) Take 50 parts of varnish, pour it into a three-necked flask, stir it magnetically at 80°C, repeatedly evacuate, and under the protection of nitrogen atmosphere, add 1 part of inorganic aluminum oxide Al2O3.

[0067] (4) Take it out and pour it into a beaker, directly add 1 part of defoaming agent Foamex 810 and EFKA-2044, stir magnetically at 40℃ for 15 minutes, ultrasonicate for 2 minutes, take it out and coat it on the glass substrate, and cure it in three stages at temperatures of 80, 160, and 220℃ respectively.

[0068] Test method: Water vapor corrosion test Figure 1 The device shown is used. Figure 1 As shown, the entire test device includes a boiler 3, a tubular muffle furnace 1, a mixer 2 and an oxygen cylinder 4. The boiler 3 serves as a steam generator, with its water inlet end connected to a pure water inlet pipe, and its water outlet end connected to the mixer 2. The oxygen cylinder 4 leads to the mixer 2, and the oxygen and water vapor are mixed and then lead to the quartz tube of the tubular muffle furnace 1.

[0069] The specific experimental operation process of water vapor corrosion is as follows:

[0070] (1) Adjust the outlet flow of the steam generator and oxygen so that the volume fraction of oxygen in the mixed atmosphere is equivalent to the volume fraction of oxygen in the air. The atmosphere mixing is carried out in a mixing chamber at 650℃.

[0071] (2) Heat the tubular muffle furnace to 650°C and introduce premixed gas into the quartz tube. After the atmosphere and environment in the quartz tube are stable, place the experimental sample in the tube for water vapor corrosion.

[0072] (3) Take samples every 20 hours and cool them to room temperature in a drying dish. Then weigh them and record the changes in mass. This process is repeated for a total of 500 hours.

[0073] Combine Figure 2 and Figure 3 Observing the surface morphology of Example 2 and Comparative Example 4, it can be seen that after the phosphate is modified by silica sol and silicone resin, the coating surface becomes denser and the surface porosity is greatly reduced. This shows that both have successfully modified the phosphate and the coating surface is smoother.

[0074] Depend on Figure 4 and Figure 5 As can be seen, Examples 1-3 exhibit a more pronounced advantage over Comparative Examples 1-4, with the comparative examples showing a greater weight gain after 100 hours of water vapor corrosion. This also demonstrates that the silica sol and silicone resin-modified phosphate improve the coating's water resistance and high-temperature resistance. Furthermore, the graph shows that the overall sample weight gain is greatest within 20-60 hours, subsequently approaching saturation. All coatings exhibit a certain degree of hydrophilicity, and the sample weight gain may be due to the hydrolysis of the generated silicates. These conclusions indicate that the dual-silicon phosphate coating exhibits excellent high-temperature resistance.

[0075] The above description of the present invention is illustrative. It is apparent that the specific implementation of the present invention is not limited to the aforementioned methods. Any non-substantial improvements made using the method concepts and technical solutions of the present invention, or any direct application of the concepts and technical solutions of the present invention to other situations without further improvement, are all within the scope of protection of the present invention. The scope of protection of the present invention shall be based on the scope of protection defined in the claims.

Claims

1. A method for preparing a double silicon modified phosphate high temperature coating, characterized in that The steps include: ① Dissolve 80-100 parts of phosphate in a solvent, stir magnetically, slowly add 10-20 parts of silicone resin, heat to 60-80°C, add 0.5-1 parts of silane coupling agent and 1-3 parts of neutral catalyst, stir magnetically to obtain modified phosphate; ② Take 40-50 parts of the modified phosphate, pour it into a container, stir it magnetically at 50-80°C, repeatedly evacuate, and under the protection of an inert gas atmosphere, add 5-10 parts of silica sol and 0.5-1 part of an inorganic curing agent; ③ After taking it out, directly add 0.5-1 parts of defoaming agent, stir magnetically at 30-40℃, ultrasonicate, take it out and spray it on the glass substrate to solidify; The above parts are all weight ratios.

2. The preparation method according to claim 1, wherein The phosphate is at least one of aluminum phosphate, aluminum dihydrogen phosphate, and aluminum hypophosphite.

3. The preparation method according to claim 1, wherein The solvent is at least one of ethanol and water.

4. The preparation method according to claim 1, wherein The silicone resin is at least one of amino silicone resin, methyl silicone resin and phenyl silicone resin.

5. The preparation method according to claim 1, characterized in that The silane coupling agent is at least one of KH550, KH560 and KH570.

6. The preparation method according to claim 1, characterized in that The neutral catalyst is at least one of dibutyltin dilaurate and stannous octoate borate.

7. The preparation method according to claim 1, characterized in that The inorganic curing agent is at least one of iron oxide Fe2O3, magnesium oxide MgO, aluminum oxide Al2O3 and zinc oxide ZnO.

8. The preparation method according to claim 1, characterized in that The particle size of the silica sol is 1 to 15 nm.

9. The preparation method according to claim 1, characterized in that The defoaming agent is at least one of BYK-024, DF-6900, Foamex 810, and EFKA-2044.

10. The preparation method according to claim 1, characterized in that The ultrasonic time in step ③ is 10 to 20 minutes.

11. The preparation method according to claim 1, characterized in that The curing in step ③ is divided into three stages in sequence, and the curing temperature of each stage is 60-80°C; 140-160°C; 200-220°C.

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