Acid and alkali corrosion resistant powder coating and preparation method thereof

Abstract

The invention discloses an acid and alkali corrosion resistant powder coating and a preparation method thereof, and relates to the field of powder coatings. The acid and alkali corrosion resistant powder coating is prepared from 440 to 450 parts by weight of bisphenol A epoxy resin, 160 to 170 parts by weight of hydroxy acrylic resin, 110 to 120 parts by weight of isocyanate terminated polyurethane resin, 28 to 33 parts by weight of amino silane coupling agent modified filler and 80 to 85 parts by weight of curing agent. The acid and alkali corrosion resistant powder coating has excellent adhesion fastness to a metal substrate, has excellent acid and alkali corrosion resistant performance, can resist a hydrochloric acid solution with the volume concentration of 5% and a sodium hydroxide solution with the mass concentration of 5% for more than 300 h, and is beneficial to protection and decoration of the substrate for a long time.

Description

Technical Field

[0001] The present application relates to the field of powder coatings, and in particular to an acid and alkali corrosion resistant powder coating and a preparation method thereof. Background Art

[0002] Traditional protective coatings often have certain limitations in terms of acid and alkali corrosion resistance. For example, under long-term acid and alkali corrosion, they are prone to blistering, peeling, discoloration, etc., causing the metal substrate to gradually lose protection and then corrode and damage. This not only increases the cost of equipment maintenance and replacement, but may also cause environmental pollution due to the leakage of metal corrosion products, and even cause safety hazards.

[0003] In order to solve the problem of acid and alkali corrosion resistance of metal substrates, people have been constantly exploring and developing new protective coatings. Powder coatings, as an environmentally friendly and efficient type of coating, have gradually attracted attention. However, the existing powder coatings still need to be further improved in terms of adhesion to metal substrates and acid and alkali corrosion resistance. Therefore, it is urgent to develop a powder coating with excellent adhesion to metal substrates and excellent acid and alkali corrosion resistance to meet the protection needs of metal products in harsh environments. Summary of the invention

[0004] In order to improve the adhesion strength of existing powder coatings to metal substrates and the acid and alkali resistance of powder coatings, the present application provides an acid and alkali corrosion resistant powder coating and a preparation method thereof.

[0005] In the first aspect, the present application provides an acid and alkali corrosion resistant powder coating adopts the following technical solution: The invention discloses an acid and alkali corrosion resistant powder coating, which comprises, based on raw materials, 440-450 parts by weight of bisphenol A epoxy resin, 160-170 parts by weight of hydroxyl acrylic resin, 110-120 parts by weight of isocyanate terminated polyurethane resin, 28-33 parts by weight of aminosilane coupling agent modified filler and 80-85 parts by weight of curing agent.

[0006] In the present application, the acid and alkali corrosion resistant powder coating is prepared by a specific ratio of bisphenol A epoxy resin, hydroxyl acrylic resin, isocyanate-terminated polyurethane resin, aminosilane coupling agent modified filler and curing agent. The acid and alkali corrosion resistant powder coating has excellent adhesion to the metal substrate and excellent acid and alkali corrosion resistance. It can withstand a hydrochloric acid solution with a volume concentration of 5% and a sodium hydroxide solution with a mass concentration of 5% for more than 300 hours, which is beneficial to long-term protection and decoration of the substrate.

[0007] In some specific embodiments, the raw materials for preparing the isocyanate-terminated polyurethane resin include polymeric diols, double-terminal hydroxyalkyl silicone oil, small molecule diol chain extender and diisocyanate, and the molar ratio of the polymeric diols, double-terminal hydroxyalkyl silicone oil, small molecule diol chain extender and diisocyanate is (0.5-0.6):(0.1-0.2):(0.05-0.06):1.

[0008] In the present application, the isocyanate-terminated polyurethane resin is prepared by reacting a polymerized diol, a double-terminated hydroxyalkyl silicone oil, a small molecule diol chain extender and a diisocyanate in a specific molar ratio, which is beneficial to further improve the adhesion between the powder coating and the substrate and the acid and alkali resistance of the powder coating. At the same time, for the thick coating film with a thickness of up to 150 μm formed by the powder coating, it can also maintain excellent surface quality and no pinhole problem occurs in the coating film.

[0009] In some specific embodiments, the polymeric diol includes non-fluorinated polyether diol and perfluoropolyether diol in a molar ratio of (3-4):1.

[0010] In some specific embodiments, the non-fluorine-containing polyether diol is at least one of polypropylene glycol, polyethylene glycol, and polytetramethylene glycol.

[0011] In some specific embodiments, the structural formula of the perfluoropolyether diol is as follows: The value range of m is 1-3, and the value range of n is 1-3.

[0012] In the present application, when non-fluorinated polyether diols, perfluoropolyether diols, double-end alcohol hydroxyalkyl silicone oils, small molecule diol chain extenders and diisocyanates are used to prepare isocyanate-terminated polyurethane resins, the perfluoropolyether diol using the perfluoropolyether diol with the above structure can further improve the acid and alkali resistance of the powder coating. At the same time, for the thick coating film with a thickness of up to 150 μm formed by the powder coating, it can also maintain excellent surface quality and no pinhole problem occurs in the coating film.

[0013] In some specific embodiments, the double-terminal alcohol hydroxyl alkyl silicone oil adopts double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H.

[0014] In some specific embodiments, the method for preparing the isocyanate-terminated polyurethane resin comprises the following steps: The polymerized diol is heated to 45-50°C according to the ratio, and then the double-terminal alcohol hydroxyalkyl silicone oil and diisocyanate are added, and the temperature is raised to 85-115°C for polymerization reaction, followed by adding a small molecule diol chain extender for chain extension reaction to obtain an isocyanate-terminated polyurethane resin.

[0015] In some specific embodiments, the epoxy equivalent of the bisphenol A epoxy resin is 600-650 g / eq.

[0016] In some specific embodiments, the curing agent is a composition of triglycidyl isocyanurate and β-hydroxyalkylamide, and the weight ratio of triglycidyl isocyanurate to β-hydroxyalkylamide is 1:(3-4).

[0017] In some specific embodiments, the aminosilane coupling agent modified filler is at least one of aminosilane coupling agent modified titanium dioxide, aminosilane coupling agent modified nano silicon powder, and aminosilane coupling agent modified nano silicon dioxide.

[0018] In a second aspect, the present application provides a method for preparing an acid and alkali corrosion resistant powder coating, comprising the following steps: A method for preparing an acid- and alkali-resistant powder coating comprises the following steps: Evenly mixing epoxy resin, hydroxy acrylic resin, isocyanate-terminated polyurethane resin, aminosilane coupling agent-modified filler and curing agent to obtain a premix; The premix is ​​melt-extruded and crushed at 90-105°C to obtain an acid- and alkali-resistant powder coating.

[0019] In the present application, the above method is used to prepare the acid and alkali corrosion resistant powder coating, which is conducive to the uniform mixing of the components and improves the product uniformity of the acid and alkali corrosion resistant powder coating.

[0020] In summary, this application at least includes the following beneficial technical effects: (1) In the present application, the acid and alkali corrosion resistant powder coating is prepared by combining bisphenol A type epoxy resin, hydroxyl acrylic resin, isocyanate terminated polyurethane resin, aminosilane coupling agent modified filler and curing agent in a specific ratio. The acid and alkali corrosion resistant powder coating has excellent adhesion to the metal substrate and excellent acid and alkali corrosion resistance. It can withstand a hydrochloric acid solution with a volume concentration of 5% and a sodium hydroxide solution with a mass concentration of 5% for more than 300 hours, which is beneficial to long-term protection and decoration of the substrate.

[0021] (2) In the present application, when non-fluorinated polyether diols, perfluoropolyether diols, double-end alcohol hydroxyalkyl silicone oils, small molecule diol chain extenders and diisocyanates are used to prepare isocyanate-terminated polyurethane resins, the perfluoropolyether diols using the perfluoropolyether diols of the above structure can further improve the acid and alkali resistance of the powder coating. At the same time, for the thick coating film formed by the powder coating with a thickness of up to 150 μm, it can also maintain excellent surface quality and no pinhole problem occurs in the coating film. DETAILED DESCRIPTION

[0022] The present application is further described below in conjunction with specific experiments.

[0023] Preparation Example [Preparation Example 1] The invention discloses an isocyanate-terminated polyurethane resin. The raw materials for preparing the resin include polytetramethylene glycol (Korea Hyosung) with a molecular weight of 1000, double-end alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol, diphenylmethane diisocyanate, dibutyltin dilaurate and acetone. The molar ratio of polytetramethylene glycol, double-end alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol and diphenylmethane diisocyanate is 0.5:0.2:0.06:1, the amount of dibutyltin dilaurate is 0.01% of the weight of diphenylmethane diisocyanate, and the amount of acetone is 20% of the weight of diphenylmethane diisocyanate.

[0024] In this preparation example, the preparation method of the isocyanate-terminated polyurethane resin comprises the following steps: According to the ratio, the temperature of polytetramethylene ether diol was raised to 45°C, and then double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, diphenylmethane diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 85°C for prepolymerization. The reaction time was 3.5 hours. Then acetone was added and stirred evenly. Propylene glycol was added for chain extension reaction. The reaction time was 1 hour. Finally, the acetone was removed and granulated to obtain isocyanate-terminated polyurethane resin.

[0025] [Preparation Example 2] The invention discloses an isocyanate-terminated polyurethane resin. The raw materials for preparing the resin include polytetramethylene glycol (Korea Hyosung) with a molecular weight of 1000, double-end alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol, isophorone diisocyanate, dibutyltin dilaurate and acetone. The molar ratio of polytetramethylene glycol, double-end alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol and isophorone diisocyanate is 0.6:0.1:0.05:1, the amount of dibutyltin dilaurate is 0.01% of the weight of isophorone diisocyanate, and the amount of acetone is 20% of the weight of isophorone diisocyanate.

[0026] In this preparation example, the preparation method of the isocyanate-terminated polyurethane resin comprises the following steps: According to the ratio, the temperature of polytetramethylene glycol was raised to 50°C, and then double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, isophorone diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 115°C for prepolymerization. The reaction time was 3 hours. Then acetone was added and stirred evenly. Propylene glycol was added for chain extension reaction. The reaction time was 1 hour. Finally, the acetone was removed and granulated to obtain isocyanate-terminated polyurethane resin.

[0027] [Preparation Example 3] An isocyanate-terminated polyurethane resin, which differs from [Preparation Example 1] in that the double-terminal hydroxyl long-chain alkyl silicone oil IOTA-8865H is replaced by an equimolar amount of polytetramethylene ether diol (Hyosung, Korea) with a molecular weight of 1000.

[0028] [Preparation Example 4] An isocyanate-terminated polyurethane resin, which differs from [Preparation Example 1] in that: in this preparation example, the raw materials for preparing the isocyanate-terminated polyurethane resin include polytetramethylene glycol (Korea Hyosung) with a molecular weight of 1000, perfluoropolyether diol, double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol, diphenylmethane diisocyanate, dibutyltin dilaurate and acetone, and the molar ratio of polytetramethylene glycol, perfluoropolyether diol, double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol and diphenylmethane diisocyanate is 0.375:0.125:0.2:0.06:1; wherein, perfluoropolyether diol and polytetramethylene glycol are added simultaneously, and the structural formula of the perfluoropolyether diol used in this preparation example is as follows: The value range of m is 1, and the value range of n is 1.

[0029] [Preparation Example 5] An isocyanate-terminated polyurethane resin, which differs from [Preparation Example 1] in that: in this preparation example, the raw materials for preparing the isocyanate-terminated polyurethane resin include polytetramethylene glycol (Korea Hyosung) with a molecular weight of 1000, perfluoropolyether diol, double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol, diphenylmethane diisocyanate, dibutyltin dilaurate and acetone, and the molar ratio of polytetramethylene glycol, perfluoropolyether diol, double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H, propylene glycol and diphenylmethane diisocyanate is 0.4:0.1:0.2:0.06:1; wherein, perfluoropolyether diol and polytetramethylene glycol are added simultaneously, and the structural formula of the perfluoropolyether diol used in this preparation example is as follows: The value range of m is 3, and the value range of n is 3.

[0030] [Preparation Example 6] An isocyanate-terminated polyurethane resin, which differs from [Preparation Example 5] in that the perfluoropolyether diol is different. In this preparation example, the structural formula of the perfluoropolyether diol is as follows: HOCH2CF2CF2(OCF2CF2CF2) a OCF2CF2O(CF2CF2CF2O) b CF2CF2CH2OH; in this preparation example, the value range of m is 3, and the value range of n is 3.

[0031] [Preparation Example 7] An isocyanate-terminated polyurethane resin, which differs from [Preparation Example 5] in that: in the perfluoropolyether diol, the values ​​of m and n are different; in this preparation example, the value range of m is 8, and the value range of n is 8. Example

[0032] [Example 1] A kind of acid and alkali corrosion resistant powder coating, comprising the following raw materials: Bisphenol A epoxy resin: 440 kg; in this embodiment, the epoxy equivalent of the bisphenol A epoxy resin is 600-650 g / eq; Hydroxylated acrylic resin: 170 kg; in this embodiment, the hydroxylated acrylic resin is BASF Joncryl@587 hydroxylated acrylic resin; Isocyanate-terminated polyurethane resin: 110 kg; in this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 1]; Aminosilane coupling agent modified filler: 28 kg; in this embodiment, the aminosilane coupling agent modified filler adopts silane coupling agent KH550 modified titanium dioxide; Curing agent: 80 kg; in this embodiment, the curing agent includes triglycidyl isocyanurate and β-hydroxyalkylamide, and the weight ratio of triglycidyl isocyanurate to β-hydroxyalkylamide is 1:3.

[0033] The preparation method of the acid and alkali corrosion resistant powder coating in this embodiment comprises the following steps: The bisphenol A epoxy resin, the hydroxy acrylic resin, the isocyanate-terminated polyurethane resin, the aminosilane coupling agent-modified filler and the curing agent are uniformly mixed to obtain a premix; The premix is ​​put into a twin-screw extruder for melt extrusion and crushing to obtain an acid and alkali corrosion resistant powder coating; wherein the temperature of the extruder zone I is 90-95°C, the temperature of the extruder zone II is 90-100°C, the temperature of the extruder zone III is 100-105°C, and the temperature of the extruder zone IV is 100-105°C.

[0034] [Example 2] A kind of acid and alkali corrosion resistant powder coating, comprising the following raw materials: Bisphenol A epoxy resin: 450 kg; in this embodiment, the epoxy equivalent of bisphenol A epoxy resin is 600-650 g / eq; Hydroxylated acrylic resin: 160 kg; in this embodiment, the hydroxylated acrylic resin is BASF Joncryl@587 hydroxylated acrylic resin; Isocyanate-terminated polyurethane resin: 120 kg; in this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 2]; Aminosilane coupling agent modified filler: 33 kg; in this embodiment, the aminosilane coupling agent modified filler adopts silane coupling agent KH550 modified titanium dioxide; Curing agent: 85 kg; In this embodiment, the curing agent includes triglycidyl isocyanurate and β-hydroxyalkylamide, and the weight ratio of triglycidyl isocyanurate to β-hydroxyalkylamide is 1:4.

[0035] The preparation method of the acid and alkali corrosion resistant powder coating in this embodiment comprises the following steps: The bisphenol A epoxy resin, the hydroxy acrylic resin, the isocyanate-terminated polyurethane resin, the aminosilane coupling agent-modified filler and the curing agent are uniformly mixed to obtain a premix; The premix is ​​put into a twin-screw extruder for melt extrusion and crushing to obtain an acid and alkali corrosion resistant powder coating; wherein the temperature of the extruder zone I is 90-95°C, the temperature of the extruder zone II is 90-100°C, the temperature of the extruder zone III is 100-105°C, and the temperature of the extruder zone IV is 100-105°C.

[0036] [Example 3] An acid and alkali corrosion resistant powder coating, which differs from [Example 1] in that: In this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 3].

[0037] [Example 4] An acid and alkali corrosion resistant powder coating, which differs from [Example 1] in that: In this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 4].

[0038] [Example 5] An acid and alkali corrosion resistant powder coating, which differs from [Example 1] in that: In this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 5].

[0039] [Example 6] An acid and alkali corrosion resistant powder coating, which differs from [Example 1] in that: In this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 6].

[0040] [Example 7] An acid and alkali corrosion resistant powder coating, which differs from [Example 1] in that: In this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 7].

[0041] Comparative Example [Comparative Example 1] A powder coating, which differs from [Example 1] in that the raw material ratios of the components are different. In this comparative example, the raw material ratios of the components are as follows: Bisphenol A epoxy resin: 550 kg; in this embodiment, the epoxy equivalent of bisphenol A epoxy resin is 600-650 g / eq; Hydroxylated acrylic resin: 120 kg; in this embodiment, the hydroxylated acrylic resin is BASF Joncryl@587 hydroxylated acrylic resin; Isocyanate-terminated polyurethane resin: 50 kg; in this embodiment, the isocyanate-terminated polyurethane resin is the isocyanate-terminated polyurethane resin prepared in [Preparation Example 1]; Aminosilane coupling agent modified filler: 28 kg; in this embodiment, the aminosilane coupling agent modified filler adopts silane coupling agent KH550 modified titanium dioxide; Curing agent: 80 kg; in this embodiment, the curing agent includes triglycidyl isocyanurate and β-hydroxyalkylamide, and the weight ratio of triglycidyl isocyanurate to β-hydroxyalkylamide is 1:3.

[0042] Performance testing 1. Adhesion grade: Use an electrostatic spray gun to spray the prepared powder on the surface treated tinplate substrate with a film thickness of 50μm, and fully cure it at 175℃ / 15min to obtain a coating. The adhesion grade of the coating is tested according to GB / T 9286-2021 "Scratching test for paint and varnish films". The lower the grade, the better the adhesion between the coating and the substrate.

[0043] 2. Acid resistance: The prepared powder was sprayed on the surface treated tinplate substrate with an electrostatic spray gun, with a film thickness of 50 μm, and fully cured at 175°C / 15 min to obtain a coating. The acid resistance of the coating was tested in accordance with the standard method A (immersion method) of GB / T 9274-1988 "Determination of resistance of paints and varnishes to liquid media". The test liquid was a 5% mass concentration hydrochloric acid solution. The coating was immersed for 300h, 450h, and 600h, and the changes on the coating surface were observed.

[0044] 3. Alkali resistance: The prepared powder was sprayed on the surface treated tinplate substrate with an electrostatic spray gun, with a film thickness of 50μm, and fully cured at 175℃ / 15min to obtain a coating. The alkali resistance of the coating was tested according to the standard method A (immersion method) of GB / T 9274-1988 "Determination of resistance of paints and varnishes to liquid media". The test liquid was a 5% mass concentration sodium hydroxide solution. The surface of the coating was immersed for 300h, 450h, and 600h, and the changes on the coating surface were observed.

[0045] 4. Graffiti pen test: Use an electrostatic spray gun to spray the prepared powder on the surface treated tinplate substrate, with film thicknesses of 50μm, 100μm, and 150μm respectively. After fully curing at 175℃ / 15min, observe whether there are pinholes or shrinkage holes on the surface of the coating.

[0046] Table 1 Sample Adhesion grade Example 1 0 Example 2 0 Example 3 1 Example 4 0 Example 5 0 Example 6 0 Example 7 0 Comparative Example 1 1 Table 2 Table 3 Combining the test results in Comparative Example 1 and Example 1 and Tables 1-3, it can be seen that when the ratio of bisphenol A epoxy resin, hydroxyl acrylic resin and isocyanate-terminated polyurethane resin in Comparative Example 1 is not within the scope of this application, the adhesion fastness of the powder coating to the substrate, the acid and alkali corrosion resistance of the powder coating and the surface quality of the coating formed by the powder coating are all significantly reduced, indicating that the ratio of bisphenol A epoxy resin, hydroxyl acrylic resin and isocyanate-terminated polyurethane resin is one of the key technical features of this application.

[0047] Combining Example 1 with Example 3 and the test results in Tables 1-3, it can be seen that compared with the isocyanate-terminated polyurethane resin prepared by reacting polytetramethylene ether diol, propylene glycol and isophorone diisocyanate, the isocyanate-terminated polyurethane resin prepared by reacting polytetramethylene ether diol, double-terminated alcohol hydroxyl long-chain alkyl silicone oil, propylene glycol and isophorone diisocyanate is beneficial to further improve the adhesion between the powder coating and the substrate and the acid and alkali resistance of the powder coating. At the same time, for the thicker coating film formed by the powder coating, it can also maintain excellent surface quality, and the coating film has no pinhole problem.

[0048] Combining the test results in Example 1, Examples 4-7 and Tables 1-3, it can be seen that when the isocyanate-terminated polyurethane resin is prepared by reacting polytetramethylene ether diol, perfluoropolyether diol, double-terminal alcohol hydroxyl long-chain alkyl silicone oil, propylene glycol, and isophorone diisocyanate, the preferred structure of the perfluoropolyether diol is: The perfluoropolyether diols with m values ​​ranging from 1 to 3 and n values ​​ranging from 1 to 3 can further improve the acid and alkali resistance of the powder coating. At the same time, for the thicker coating film formed by the powder coating, the excellent surface quality can be maintained and the coating film will not have pinhole problems.

[0049] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An acid and alkali corrosion resistant powder coating, characterized in that: Calculated by raw materials, the invention comprises 440-450 parts by weight of bisphenol A epoxy resin, 160-170 parts by weight of hydroxy acrylic resin, 110-120 parts by weight of isocyanate-terminated polyurethane resin, 28-33 parts by weight of aminosilane coupling agent-modified filler and 80-85 parts by weight of curing agent.

2. The acid and alkali corrosion resistant powder coating according to claim 1, characterized in that: The raw materials for preparing the isocyanate-terminated polyurethane resin include polymeric diol, double-terminal alcohol hydroxyalkyl silicone oil, small molecule diol chain extender and diisocyanate, and the molar ratio of the polymeric diol, double-terminal alcohol hydroxyalkyl silicone oil, small molecule diol chain extender and diisocyanate is (0.5-0.6): (0.1-0.2): (0.05-0.06):

1.

3. The acid and alkali corrosion resistant powder coating according to claim 2, characterized in that: The polymer diol includes non-fluorinated polyether diol and perfluoropolyether diol in a molar ratio of (3-4):

1.

4. The acid and alkali corrosion resistant powder coating according to claim 3, characterized in that: The non-fluorine-containing polyether diol is at least one of polypropylene glycol, polyethylene glycol and polytetramethylene glycol.

5. The acid and alkali corrosion resistant powder coating according to claim 3, characterized in that: The structural formula of the perfluoropolyether diol is as follows: The value range of m is 1-3, and the value range of n is 1-3.

6. The acid and alkali corrosion resistant powder coating according to claim 2, characterized in that: The double-terminal alcohol hydroxyl alkyl silicone oil adopts double-terminal alcohol hydroxyl long-chain alkyl silicone oil IOTA-8865H.

7. The acid and alkali corrosion resistant powder coating according to any one of claims 2 to 6, characterized in that: The preparation method of the isocyanate-terminated polyurethane resin comprises the following steps: The polymerized diol is heated to 45-50°C according to the ratio, and then the double-terminal alcohol hydroxyalkyl silicone oil and diisocyanate are added, and the temperature is raised to 85-115°C for polymerization reaction, followed by adding a small molecule diol chain extender for chain extension reaction to obtain an isocyanate-terminated polyurethane resin.

8. The acid and alkali corrosion resistant powder coating according to claim 1, characterized in that: The epoxy equivalent of the bisphenol A epoxy resin is 600-650 g / eq.

9. The acid and alkali corrosion resistant powder coating according to claim 1, characterized in that: The curing agent is a composition of triglycidyl isocyanurate and beta-hydroxyalkylamide, and the weight ratio of the triglycidyl isocyanurate to the beta-hydroxyalkylamide is 1:(3-4).

10. A method for preparing an acid- and alkali-resistant powder coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: The bisphenol A epoxy resin, the hydroxy acrylic resin, the isocyanate-terminated polyurethane resin, the aminosilane coupling agent-modified filler and the curing agent are uniformly mixed to obtain a premix; The premix is ​​melt-extruded and crushed at 90-105°C to obtain an acid- and alkali-resistant powder coating.

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