CN115304940A - Long-acting non-stick coating and preparation and construction method thereof - Google Patents

Abstract

The invention discloses a long-acting non-stick coating and a preparation and construction method thereof; the coating is a double-coating, and the primer comprises, by 100% of the total weight, 26-28% of silica sol, 4-5% of NaOH solution by 1%, 10-12% of pigment, 8-10% of filler, 1-1.5% of dispersant, 28-30% of silane, 3-3.5% of isopropanol, 6-8% of silicone oil microcapsule, 0.7-1% of 25% of formic acid and the balance of deionized water; the finishing coat comprises 1-2% of fluorosilane, 3-5% of acetic acid, and the balance of deionized water and isopropanol in equal mass ratio, wherein the total weight is 100%. The invention organically combines the non-adhesiveness of the fluorocarbon finish paint and the high hardness of the ceramic primer through the coupling effect of the fluorosilane to prepare the long-acting non-adhesiveness coating; and the silicone oil microcapsule is added into the primer, so that the non-stick property can be continuously provided for the coating after the finish is worn, the non-stick durability is greatly improved, and the non-stick property of the coating can be maintained for more than 3 years.

Description

Long-acting non-stick coating and preparation and construction method thereof

Technical Field

The invention belongs to the technical field of coatings, and relates to a long-acting non-stick coating and a preparation and construction method thereof.

Background

In recent years, the ceramic coating has obvious advantages of health, safety and environmental protection, is more and more applied to the inner surface of the non-stick pan, and the non-stick property of the ceramic coating is obviously improved along with the progress of the non-stick technology. But because the non-stick property of the ceramic coating surface is dependent on-CH ₃ Provided by the low surface energy of the radical, -CH ₃ Is about 21-23mN/m, is still slightly higher than the 17-19mN/m surface free energy of-F, so although scientists are constantly exploring the improvement of non-tackiness of ceramic coatings, there is a large gap compared to fluorocarbon non-tacky coatings, the fundamental reason being that the difference in surface free energy is due to the difference in the groups providing the non-tackiness.

The hardness of the fluorocarbon coating is only 2H at normal temperature, when the fluorocarbon coating is used as an anti-sticking pan coating, the temperature of the pan often reaches one or two hundred degrees in the cooking process, the fluorocarbon coating belongs to thermoplastic materials and can be softened at high temperature, the hardness cannot reach H, the coating is easily scratched by a shovel or food materials to cause abrasion and the like, and then the coating at the scratched part drops, at the moment, although the coating is not sticky, the exposed aluminum base material can enter the intestinal tract of people along with food, the body health can be influenced in the past for a long time, so that the anti-sticking pan coating is good in appearance and good in appearanceAlthough the fluorocarbon coating is good in non-stick durability, once the coating is damaged, the cooker needs to be replaced in time, and the service life of the cooker is generally within 1 year. The ceramic coating is made of an inorganic structure of Si-O-Si, the hardness of the coating reaches 9H, but the surface of the coating plays a non-stick role in-CH ₃ The chemical bond of the group can be broken along with the prolonging of the service life at high temperature, and particularly, when the phenomena of dry burning, pan pasting and the like occur during cooking, the non-stick property can be rapidly reduced, so that the service life of the non-stick pan with the ceramic coating is about half a year, and the service life is far from the expectation of a user. How to combine the high hardness of the ceramic coating with the non-stick durability of the fluorocarbon coating to prepare the long-acting non-stick coating is a problem to be solved.

The search of the existing patent documents shows that the Chinese patent ZL202110120123.9 discloses a technical scheme of a graphene non-stick coating, graphene is added into a primer and a finish to form an interpenetrating network structure, and a ceramic coating is combined with a fluorocarbon coating, but the technical scheme only utilizes the non-stick property of the fluorocarbon finish, silicone oil is not added into the primer, the finish coating is thin, and once the fluorocarbon finish is worn, the non-stick property disappears instantly, so the improvement effect of the technical scheme on the non-stick durability is not obvious.

Disclosure of Invention

The invention aims to overcome the defects that the prior art has a non-stick pan coating, the fluorocarbon coating is easily scratched to expose a base material during cooking due to low hardness, particularly lower hardness at high temperature, and the service life is less than 1 year; the ceramic coating, although having a high hardness, provides a non-stick-CH due to the high temperature ₃ The groups can be broken along with the prolonging of the service time, the non-stick durability is poor, the service life of the coating is about half a year and the like, and the long-acting non-stick coating and the preparation and construction methods thereof are provided. The invention combines the advantages of the fluorocarbon coating and the ceramic coating to prepare the long-acting non-sticky coating.

The purpose of the invention is realized by the following technical scheme:

< first aspect >

The invention relates to a long-acting non-stick double-coating paint, wherein a primer is a ceramic coating, and a finish paint is a fluorocarbon coating;

the primer comprises the following components in percentage by total weight of 100 percent: silica sol: 26-28%,1% naoh solution: 4-5%, pigment: 10-12%, filler: 8-10%, dispersant: 1-1.5%, silane: 28-30%, isopropanol: 3-3.5%, silicone oil microcapsule: 6-8%,25% formic acid: 0.7-1%, deionized water: the balance;

the finishing coat comprises the following components by the total weight of 100 percent: fluorosilane: 1-2%, acetic acid: 3-5%, deionized water and isopropanol in a mass ratio of 1:1: and the balance.

In the primer, silica sol is the main film forming material of the ceramic coating, and common commercial products such as: bindzil 2034DI from Acksonobel, ST-O-40 from Nissan Chemicals, grace

HS-40 and the like.

In the primer, 1 percent of NaOH solution is used as a color paste pH value regulator, the pH value of a color paste part is regulated to 9-10.5, the condition that the pH value is reduced in the storage process after the color paste is ground by silica sol, and when the pH value is reduced to be below 8.5 and is close to neutral, the silica sol is gelatinized to cause the color paste to deteriorate, so that the pH value of the color paste is regulated to 9-10 by using alkaline solution to ensure that the color paste cannot deteriorate during storage.

In the primer, pigments endow the paint with different colors, common inorganic pigments are selected, the inorganic pigments have good temperature resistance and good safety, and the inorganic pigments are preferably selected in the field of high temperature resistance. Such as titanium dioxide, iron oxide yellow, manganese iron black, cobalt blue, iron oxide red, etc.

In the primer, the filler plays roles of reducing the cost of the coating, increasing the solid content of the coating and the like, and common fillers are selected, such as: mica powder, silicon micropowder, kaolin, alumina powder, fumed silica and the like.

In the primer, the dispersant functions to reduce the time for dispersing the pigment filler, stabilize the pigment dispersion, improve the coloring power and hiding power of the pigment, and the like, for example: BYK180, BYK190, BYK2010, BYK2001, etc.

In the primer, silane is an auxiliary film forming substance, and methyl trimethoxy silane, methyl triethoxy silane, dimethyl dimethoxy silane and the like can be selected.

In the primer, 25% formic acid solution is a catalyst for ceramic coating sol-gel reaction, and silane is hydrolyzed under acidic condition and then undergoes polycondensation reaction with silica sol to generate the ceramic coating.

In the primer, the silicone oil microcapsule provides a non-sticky component of the primer of the ceramic coating, and is a microcapsule with a shell-core structure, and silicone oil can gradually diffuse out of the shell structure in the heating process of the coating, so that the non-sticky property is slowly released, and the non-sticky durability of the coating is prolonged.

In the top coat, the fluorosilane is a film-forming substance and can also be used as a coupling agent with the primer, heptadecafluorodecyltrimethoxysilane or heptadecafluorodecyltriethoxysilane is selected, the non-stick property of the coating is poor when the number of-F is small, and the good non-stick property can be achieved only by using at least seventeen-F silanes.

In the finish paint, acetic acid is a catalyst for hydrolytic polymerization of fluorosilane, and fluorosilane is hydrolyzed under an acidic condition to form a colorless transparent solution, so that colorless transparent finish paint is favorably formed.

As an embodiment, the silicone oil microcapsules are formulated as follows: silicone oil: 43-45%, silane: 48-50%, surfactant: 4-4.5%,25% formic acid solution: and (4) the balance.

In the silicone oil microcapsule, silicone oil: to provide non-tackiness of the ceramic coating primer, silicone oils are commonly used, such as: methyl silicone oil, hydroxy silicone oil, and the like.

In the silicone oil microcapsule, silane: the method is characterized by comprising the following steps of 1:1-2:1 and a difunctional silane. The trifunctional silane is short-chain trifunctional silane which comprises methyltrimethoxysilane and methyltriethoxysilane; the difunctional silane is a short-chain difunctional silane and comprises dimethyl dimethoxy silane, dimethyl diethoxy silane and the like. The three-functionality silane and the two-functionality silane are selected and used in a matched mode, a regular porous structure with a three-dimensional cross-linking structure can be formed, the diameter of a hole is large, the diffusion of silicon oil molecules is facilitated, and if the three-functionality silane is selected, the formed cross-linking structure is compact, the hole diameter is small, and the outward diffusion of the silicon oil molecules is not facilitated. The silane with short chain alkyl can avoid the steric hindrance effect in the later polymerization stage, so that the shell structure is more complete and regular. The proportion of the trifunctional silane to the difunctional silane is more than 2:1, the trifunctional silane is too much, the formed cross-linked structure is compact, the mesh diameter is small, and the outward diffusion of silicone oil molecules is not facilitated; the mixture ratio is less than 1:1, the bifunctional silane is too much to form a complete crosslinking structure, a plurality of chain segments with linear structures are generated, the release speed of the silicone oil is too high, floating oil is easy to generate on a coating, and the non-stick durability is poor.

In the silicone oil microcapsule, the surfactant is selected from cationic surfactants, and can stably exist under the weak acidic condition. For example: surfactants with organic quaternary ammonium salt structure such as cetyl trimethyl quaternary ammonium bromide, octadecyl dimethyl benzyl quaternary ammonium chloride, benzalkonium chloride and benzalkonium bromide.

In the silicone oil microcapsule, 25% formic acid solution is a catalyst for silane hydrolysis, and the silane is hydrolyzed under acidic conditions to form colorless transparent solution.

As an embodiment of the present invention, the preparation of the silicone oil microcapsule comprises: mixing silicone oil, silane with mixed three-functionality and two-functionality, and surfactant uniformly, adjusting pH to 4.0-5.0 with 25% formic acid under stirring, reacting for 4-6hr, and performing ultrasonic treatment for 2-2.5hr to obtain silicone oil microcapsule. The microcapsule is a shell-core structure, wherein the shell is a three-dimensional cross-linked network structure of Si-O-Si formed by hydrolytic polymerization of silane under an acidic condition, and the core is silicone oil emulsified by a surfactant. The reticular shell structure can make the silicon oil molecules inside slowly diffuse outwards.

The silicone oil can be uniformly dispersed in the coating under the action of the surfactant and can also be uniformly distributed in the coating after curing, and when the silicone oil on the upper layer of the primer loses the action in the use process, the silicone oil in the coating can be slowly diffused out at high temperature, so that the long-acting non-stickiness of the coating is ensured. If the silicone oil is directly added into the ceramic coating, the silicone oil has low density and poor compatibility with the water-based coating, and only floats on the surface of the coating, and after the coating is cured into a film, the silicone oil is also positioned on the surface of the coating, and once the silicone oil loses effect, the non-stick property disappears, so that the non-stick durability of the coating directly added with the silicone oil is poor.

The step adopts a mode of firstly stirring for reaction for 4-6 hours and then carrying out ultrasonic treatment for 2-2.5 hours, the reaction is carried out under stirring to mainly generate a shell structure, the silicone oil and the surfactant are primarily combined, and the silicone oil and the surfactant are further emulsified under the ultrasonic treatment to form uniform and stable silicone oil microcapsule dispersion liquid.

< second aspect >

The invention relates to a preparation method of a long-acting non-stick double-coating paint, which comprises the following steps:

a1, color paste preparation: mixing silica sol, pigment, filler, dispersant and deionized water uniformly, adjusting pH to 9.5-10.5 with 1% NaOH solution, and grinding to fineness of 20 μm or less;

a2, preparing a ceramic coating primer: uniformly mixing silane, isopropanol, silicone oil microcapsules and 25% formic acid, then adding the color paste prepared in the step A1, uniformly mixing, and reacting for 4-8 hours to obtain the ceramic paint primer;

a3, preparing fluorocarbon finish: and uniformly mixing fluorosilane, acetic acid, deionized water and isopropanol, and reacting for 8-16 hours to obtain finish paint. In this step, since the fluorosilane has a longer molecular chain and a slower hydrolysis rate, the reaction time is also longer.

In the step A1, after grinding to the fineness of less than 20 μm, the pH value of the color paste is tested again, and if the pH value is less than 9.0 percent, the pH value is adjusted to 9.0-10.0 percent by using 1 percent NaOH solution for standby.

< third aspect >

The invention relates to an application method of a long-acting non-stick double-coating paint, which comprises the following steps:

b1, sandblasting the metal base material until the roughness Ra =2.5-4 μm, cleaning and drying;

b2, preheating the metal substrate to 45-55 ℃, spraying a primer, baking for 3-5 minutes at 80-100 ℃, taking out and cooling to room temperature, wherein the thickness of the primer is about 20-30 μm;

b3, spraying finish paint, standing for 5-10 minutes, putting into an oven at 200-260 ℃ for baking for 10-15 minutes, taking out and cooling to room temperature. The thickness of the cured topcoat, i.e., the dry film thickness, is about 5 to 10 μm.

In step B1, the metal substrate includes an aluminum alloy substrate, stainless steel, and the like.

In the step B2, the curing temperature is not easy to be too high, the time is not too long, so that the primer reaches a finger-dry state rather than a solid-dry state, namely, the surface is not sticky when touched by fingers, but the inside is not completely dry, and at the moment, a large amount of-OH exists on the surface of the primer, which is beneficial to the coupling and combination between the finish paint and the primer, and the firm adhesive force between the two layers is ensured.

And B3, standing for 5-10 minutes after the finish paint is sprayed, wherein the process is favorable for the diffusion of molecules, and the molecules of the coupling agent migrate to the bonding interface of the finish paint and the finish paint to generate the coupling effect. And the mixture is placed for a period of time and then cured, so that the coupling agent is ensured to finish the migration process, and better adhesion between the primer and the finish paint can be obtained. The coupling agent also contains a large amount of-OH, and can be firmly combined with the-OH on the surface of the primer through coupling action.

The coating obtained by the method organically combines the high hardness of the ceramic coating with the non-stick durability of the fluorocarbon coating. the-F contained in the finish paint has excellent long-acting non-adhesiveness, when the cooker is used, the non-adhesiveness is provided by the finish paint firstly, and when the finish paint is worn, the silicone oil in the primer paint is slowly diffused from the microcapsule at high temperature to continuously provide the non-adhesiveness for the coating. Because the ceramic paint primer has high hardness, the wear resistance of the fluorine-containing finish paint is greatly improved, and the service life of the finish paint is effectively prolonged. The non-stick coating prepared by the method has the non-stick property of more than 3 years.

Compared with the prior art, the invention has the following beneficial effects:

(1) Coating and modifying the surface of the ceramic coating by using fluorosilane hydrolysate, and organically combining the non-adhesiveness of the fluorocarbon finish paint and the high hardness of the ceramic coating primer through the coupling effect of fluorosilane to prepare a coating with long-acting non-adhesiveness;

(2) The silicone oil microcapsule with a shell-core structure is prepared by a hydrolytic polymerization technology of silane and an emulsification technology of a surfactant on silicone oil, wherein the shell is a three-dimensional cross-linked network structure of Si-O-Si formed by hydrolytic polymerization of silane, and the core is silicone oil emulsified by the surfactant, so that the silicone oil and the water-based ceramic coating have good compatibility and can be uniformly dispersed in the whole coating, and the silicone oil can be slowly diffused out at high temperature, thereby improving the non-stick durability of the coating;

(3) The silicone oil microcapsule is added into the primer, so that the non-stick property can be continuously provided for the coating after the finish is worn, the non-stick durability is greatly improved, and the non-stick property of the coating can be kept for more than 3 years.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that numerous modifications and adaptations can be made by those skilled in the art without departing from the inventive concepts herein. All falling within the scope of the present invention.

Examples 1 to 3

Examples 1-3 provide a long-life non-stick coating having the composition shown in table 1.

The preparation steps of the long-acting non-stick coating are as follows:

(1) Color paste preparation: uniformly mixing silica sol, pigment, filler, dispersant and deionized water, adjusting the pH value to 10 by using 1 percent NaOH solution, grinding the mixture to the fineness of less than 20 mu m, testing the pH value of the color paste, and adjusting the pH value to 9.5 by using 1 percent NaOH solution if the pH value is less than 9.0 for standby;

(2) Preparing a ceramic paint primer: uniformly mixing silane, isopropanol, silicone oil microcapsules and 25% formic acid, then adding the color paste prepared in the step (1), uniformly mixing, and reacting on a roller frame for 6 hours to obtain the ceramic paint primer.

(3) Preparing fluorocarbon finish:

and uniformly mixing the fluorosilane, the acetic acid and the water-alcohol mixed solution, and reacting on a roller frame for 12 hours to obtain the finish paint.

The construction steps of the long-acting non-stick coating are as follows:

(1) Sandblasting an aluminum alloy base material until the roughness Ra =3 μm, cleaning the aluminum alloy base material by tap water, and drying the aluminum alloy base material in an oven for later use;

(2) Preheating a base material to 50 ℃, spraying a primer, baking for 4 minutes at 90 ℃, taking out and cooling to room temperature, wherein the thickness of the primer is about 25 mu m;

(3) Spraying finish paint, standing for 8 minutes, putting into a baking oven at 240 ℃, baking for 12 minutes, taking out and cooling to room temperature; the thickness of the topcoat was about 8 μm.

Comparative example 1

The present comparative example provides a non-stick coating having the composition shown in table 1; the construction procedure was the same as in example 1.

The preparation steps of the long-acting non-stick coating are as follows:

(1) Color paste preparation: mixing silica sol, pigment, filler, dispersant and deionized water uniformly, adjusting pH to 10 with 1% NaOH solution, grinding to fineness below 20 μm, testing pH of the color paste, and adjusting to 9.5 with 1% NaOH solution if less than 9.0;

(2) Preparation of ceramic paint primer: uniformly mixing silane, isopropanol, silicone oil, surfactant (octadecyl dimethyl benzyl ammonium chloride) and 25% formic acid, then adding the color paste prepared in the step (1), uniformly mixing, and reacting on a roller frame for 6 hours to obtain the ceramic coating primer.

(3) Preparing fluorocarbon finish:

and uniformly mixing the fluorosilane, acetic acid and water-alcohol mixed solution, and reacting on a roller frame for 12 hours to obtain finish paint.

Comparative examples 2 to 7

Comparative examples 2-7 provide a non-stick coating having the composition shown in table 1. The preparation and application steps were the same as in example 1.

Table 1 coating composition and amount (wt.%) of examples and comparative examples

In table 1, the hydroalcoholic solution is a mixed solution of deionized water and isopropanol in a mass ratio of 1:1;

silicone oil microcapsule 1: uniformly mixing 45% of methyl silicone oil, 48% of silane (methyltrimethoxysilane and dimethyldimethoxysilane in equal mass ratio) and 4% of surfactant (octadecyl dimethyl benzyl ammonium chloride), adjusting the pH value to 5 with 25% of formic acid under stirring, reacting for 6hr, and performing ultrasonic treatment for 2hr to obtain silicone oil microcapsule 1;

silicone oil microcapsule 2: uniformly mixing 45% of methyl silicone oil, 48% of silane (equal mass ratio of methyltrimethoxysilane and methyltriethoxysilane) and 4% of surfactant (octadecyl dimethyl benzyl ammonium chloride), adjusting the pH value to 5 with 25% of formic acid under stirring, reacting for 6hr, and performing ultrasonic treatment for 2hr to obtain silicone oil microcapsule 2;

silicone oil microcapsule 3: uniformly mixing 45% of methyl silicone oil, 48% of silane (dimethyl dimethoxy silane and dimethyl diethoxy silane in equal mass ratio) and 4% of surfactant (octadecyl dimethyl benzyl ammonium chloride), adjusting the pH value to 5 by using 25% of formic acid under the stirring state, reacting for 6hr, and performing ultrasonic treatment for 2hr to obtain silicone oil microcapsules 3;

silicone oil microcapsule 4: uniformly mixing 45% of methyl silicone oil, 48% of silane (hexadecyl trimethoxy silane and dimethyl dimethoxy silane in equal mass ratio) and 4% of surfactant (octadecyl dimethyl benzyl ammonium chloride), adjusting the pH value to 5 by using 25% of formic acid under the stirring state, reacting for 6hr, and performing ultrasonic treatment for 2hr to obtain silicone oil microcapsules 4;

silicone oil microcapsule 5: uniformly mixing 45% of methyl silicone oil, 48% of silane (methyl trimethoxy silane and dimethyl dimethoxy silane with the mass ratio of 1:3) and 4% of surfactant (octadecyl dimethyl benzyl ammonium chloride), adjusting the pH value to 5 by using 25% of formic acid under the stirring state, reacting for 6 hours, and performing ultrasonic treatment for 2 hours to obtain a silicone oil microcapsule 5;

silicone oil microcapsule 6: 0.25 g of sodium dodecyl sulfate and 0.75 g of alkylphenol polyoxyethylene are dissolved in 100 g of deionized water, then an oil phase mixture consisting of 10 g of dimethyl silicone oil, 10 g of TEOS and 1.5 g of octadecyl trimethoxy silane is added, pre-emulsification and stirring are carried out for 15 minutes in an ice water bath environment, and then ultrasonic fine emulsification is carried out for 20 minutes by using a cell crusher to obtain the miniemulsion. And adjusting the pH value of the miniemulsion to 7.5, and stirring at a high speed for 24 hours at normal temperature to obtain the milky white silicone oil microcapsule 6.

Testing of key properties

The main performance tests are performed on the coatings prepared by the construction of the above examples and comparative examples, the detection items and methods are shown in table 2, and the detection results are shown in table 3:

TABLE 2

TABLE 3

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims (10)

1. A long-acting non-stick double-coating paint composition is characterized in that a primer is a ceramic coating, and a finish paint is a fluorocarbon coating;

the primer comprises the following components in percentage by total weight of 100 percent: silica sol: 26-28%,1% naoh solution: 4-5%, pigment: 10-12%, filler: 8-10%, dispersant: 1-1.5%, silane: 28-30%, isopropanol: 3-3.5%, silicone oil microcapsule: 6-8%,25% formic acid: 0.7-1%, deionized water: the balance;

the finishing coat comprises the following components by the total weight of 100 percent: fluorosilane: 1-2%, acetic acid: 3-5%, deionized water and isopropanol in a mass ratio of 1:1: and (4) the balance.

2. The long-acting non-stick dual coating composition of claim 1, wherein the silica sol is selected from Bindzil 2034DI, nissan chemical ST-O-40, grace

One or more of HS-40; the silane is selected from one or more of methyltrimethoxysilane, methyltriethoxysilane and dimethyldimethoxysilane.

3. The long acting non-stick dual coat coating composition of claim 1 wherein the pigment is an inorganic pigment; the filler is selected from one or more of mica powder, silica micropowder, kaolin, alumina powder and gas-phase silica; the dispersing agent is selected from one or more of BYK180, BYK190, BYK2010 and BYK 2001.

4. The long acting non-stick dual coat coating composition of claim 1, wherein said fluorosilane is heptadecafluorodecyltrimethoxysilane or heptadecafluorodecyltriethoxysilane.

5. The long-acting non-stick dual coating composition according to claim 1, wherein the silicone oil microcapsules comprise 43-45% silicone oil, 48-50% silane, 4-4.5% surfactant, and the balance 25% formic acid solution, based on the total weight of 100%.

6. The long-acting non-stick double-coating paint composition according to claim 5, wherein the silicone oil is one or more of methyl silicone oil and hydroxyl silicone oil; the silane consists of 1:1-2:1 and a difunctional silane.

7. The long-acting non-stick dual coating composition of claim 5, wherein said surfactant is selected from cationic surfactants of organic quaternary ammonium structure, comprising: one or more of cetyl trimethyl quaternary ammonium bromide, octadecyl dimethyl benzyl quaternary ammonium chloride, benzalkonium chloride, and benzalkonium bromide.

8. The long-acting non-stick dual coating composition according to claim 5, wherein the silicone oil microcapsules are prepared by: mixing silicone oil, silane with mixed three-functionality and two-functionality, and surfactant uniformly, adjusting pH to 4.0-5.0 with 25% formic acid under stirring, reacting for 4-6hr, and performing ultrasonic treatment for 2-2.5hr to obtain silicone oil microcapsule.

9. A method for preparing the long-acting non-stick double coating paint according to claim 1, characterized in that it comprises the following steps:

a1, color paste preparation: uniformly mixing silica sol, pigment, filler, dispersant and deionized water, adjusting the pH value to 9.5-10.5 by using 1 percent of NaOH solution, and grinding the mixture to the fineness of less than 20 mu m;

a2, preparing a ceramic coating primer: uniformly mixing silane, isopropanol, silicone oil microcapsules and 25% formic acid, then adding the color paste prepared in the step A1, uniformly mixing, and reacting for 4-8 hours to obtain the ceramic paint primer;

a3, preparation of fluorocarbon finish: and uniformly mixing fluorosilane, acetic acid, deionized water and isopropanol, and reacting for 8-16 hours to obtain the finish paint. In this step, since the fluorosilane has a longer molecular chain and a slower hydrolysis rate, the reaction time is also longer.

10. A method of applying the long acting non-stick duplex coating of claim 1, comprising the steps of:

b1, sandblasting the metal base material until the roughness Ra =2.5-4 μm, cleaning and drying;

b2, preheating the metal substrate to 45-55 ℃, spraying a primer, baking for 3-5 minutes at 80-100 ℃, taking out and cooling to room temperature, wherein the thickness of the primer is about 20-30 μm;

b3, spraying finish paint, standing for 5-10 minutes, putting into an oven at 200-260 ℃ for baking for 10-15 minutes, taking out and cooling to room temperature.