Polyester resin for high-temperature-resistant and high-leveling HAA powder coating and preparation method

Abstract

The invention relates to polyester resin for a high-temperature-resistant and high-leveling HAA powder coating, and the polyester resin is obtained by polymerizing the following raw materials: chlorophenyl methyl dichlorosilane, dimethyl dichlorosilane, 2-methyl-1, 3-propylene glycol, 3-tert-butyl dimethyl siloxy glutaric anhydride, neopentyl glycol and 2-ethyl-2-methylsuccinic acid. The prepared polyester resin is low in acid value and large in terminal carboxyl steric hindrance, on one hand, the use amount of an HAA curing agent needed during curing is small, the cost of the powder coating is reduced, on the other hand, water molecules generated during curing are reduced, the curing and leveling time is prolonged, full escape of small molecule water is facilitated, the effect of resisting thick coating pinholes is obvious, and the coating effect is good. And a coating film cured with HAA is resistant to high temperature and relatively good in leveling property.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester resins, and in particular to a polyester resin for high-temperature resistant and high-leveling HAA powder coating and a preparation method thereof. Background Art

[0002] With the strengthening of environmental awareness and environmental protection requirements, powder coatings are widely used compared to solvent-based coatings because of their advantages of no solvent pollution, 100% film formation, and low energy consumption. They are especially widely used in some special high-temperature resistant application fields, such as household microwave ovens or factory microwave reaction devices, ovens, drying rooms, etc., which require high high-temperature resistance of powder coatings. In order to meet the high-temperature resistance requirements of these fields, a common method is to add silicone resins for mixed modification. Since silicone resins are generally compatible with polyester resins or epoxy resins, the physical mixing channel has poor compatibility, resulting in defects such as poor leveling and loss of gloss. Although there are also synthetic modifications for polyester resins, phenolic resins or special polyimides or polyphenol oxide resins are often used, which have too high segment rigidity, poor leveling, and high cost, making them difficult to use on a large scale. The commonly used powder coating curing systems are mainly TGIC and HAA. Compared with the TGIC curing system, HAA has a series of advantages such as low cost, high functionality, small amount used in powder coatings, and non-toxicity. However, due to its high functionality, its leveling is worse than the TGIC curing system, and small molecules of water escape during the curing process. It is also worse than TGIC in terms of resistance to thick coating pinholes. How to develop a polyester resin with high leveling, resistance to thick coating pinholes and excellent high temperature resistance for the HAA system is a research direction in the industry. Summary of the invention

[0003] In view of the shortcomings of the current HAA curing system powder coating in terms of high temperature resistance, leveling and resistance to thick coating pinholes, the present invention develops a polyester resin for HAA powder coating that is resistant to high temperature, has high leveling and has resistance to thick coating. The polyester resin is obtained by polymerization of raw materials including chlorophenylmethyldichlorosilane, dimethyldichlorosilane, 2-methyl-1,3-propanediol, 3-tert-butyldimethylsiloxyglutaric anhydride, neopentyl glycol, and 2-ethyl-2-methylsuccinic acid. A special copolymerized organic silicon segment structure with excellent high temperature resistance and lubrication performance is introduced into the polyester structure through reaction. At the same time, the silicon-containing dibasic acid 3-tert-butyldimethylsiloxyglutaric anhydride and neopentyl glycol are copolymerized and grafted to extend the chain. Finally, a high steric hindrance flexible monomer 2-ethyl-2-methylsuccinic acid is used for end-capping to obtain a low acid value, low activity flexible terminal carboxyl polyester resin, which achieves the effect of slowing down the curing speed and increasing the leveling time. At the same time, due to the large amount of silicone copolymer chain segments used, the high temperature resistance is good, and the polyester resin chain segments are soft and have good lubricity, a low softening point, and good fluidity during high temperature curing.

[0004] A polyester resin for high temperature resistant and high leveling HAA powder coating, the polyester resin comprising the following raw materials in molar proportions:

[0005]

[0006] The raw materials also include catalyst 1, catalyst 2 and an antioxidant.

[0007] Preferably, catalyst 1 is ethylenediamine, and the amount used is 10-15% of the mass of dimethyldichlorosilane. Catalyst 2 is tetrabutyl titanate, and the amount used is 1-1.3% of the mass of 3-tert-butyldimethylsiloxyglutaric anhydride. The antioxidant is a mixture of antioxidant 1076 and antioxidant 168, the mass ratio of the two is 3:1, and the amount used is 2-3% of the mass of 3-tert-butyldimethylsiloxyglutaric anhydride.

[0008] The method for preparing a polyester resin for high temperature resistant and high leveling HAA powder coating comprises the following steps:

[0009] A. Add the formulated amount of toluene, 2-methyl-1,3-propanediol and catalyst 1 into a reaction kettle, start stirring and heat to 50-55° C. and then keep warm, then slowly dropwise add the formulated amount of a mixed solution of chlorophenylmethyldichlorosilane and dimethyldichlorosilane, and simultaneously introduce nitrogen for bubbling to quickly lead the generated hydrogen chloride gas out of the reaction system. After the dropwise addition is completed, continue to keep warm for reaction;

[0010] B. Sampling and testing. When the contents of free chlorophenylmethyldichlorosilane and dimethyldichlorosilane monomers are both lower than 0.5%, it indicates that the chain extension polymerization of the organosilicon monomer is basically completed. At this time, the by-product ethylenediamine hydrochloride solid is removed by vacuum filtration. The obtained filtrate is heated to 125-130° C., and the toluene solvent and the residual very small amount of ethylenediamine are removed during the heating process;

[0011] C. When the toluene content is less than 2%, add the catalyst 2 and the silicon-containing chain extender 3-tert-butyldimethylsilyloxyglutaric anhydride in the formula amount to carry out chain extension reaction, and gradually raise the temperature to 200-210° C. and keep the temperature to carry out chain extension reaction; take samples for testing, and when the acid value of the polymer reaches 40-48 mgKOH / g, add the neopentyl glycol in the formula amount, and raise the temperature to 225-230° C. to carry out chain extension reaction;

[0012] D. Take samples for testing. When the acid value of the polymer reaches 25-32 mgKOH / g, add antioxidant, stir evenly, start the vacuum system, and continue the vacuum polycondensation reaction at 225-230°C;

[0013] E. When the acid value of the reactant reaches 10-15 mgKOH / g, release the vacuum, add 2-ethyl-2-methylsuccinic acid, and continue to carry out the end-capping reaction at 225-230° C. until the acid value of the polymer reaches 22-27 mgKOH / g, stop the reaction, discharge the material while hot, cool the polyester resin, and then crush and granulate it to obtain the polyester resin.

[0014] Preferably, in step A, the dropping time is controlled at 2-2.5h; in step C, the temperature is gradually increased to 200-210°C at a heating rate of 20-25°C / h; in step D, the vacuum degree is controlled at -0.097 to -0.099Mpa; in step E, the polyester resin is cooled with a steel belt with condensed water.

[0015] For example, the polyester resin method described above comprises the following steps:

[0016] A. Add the formulated amount of toluene, 2-methyl-1,3-propanediol and catalyst 1 into a reaction kettle, start stirring and heat to 50-55° C. and then keep warm, then slowly dropwise add the formulated amount of a mixed solution of chlorophenylmethyldichlorosilane and dimethyldichlorosilane, and simultaneously introduce nitrogen for bubbling to quickly lead the generated hydrogen chloride gas out of the reaction system. After the dropwise addition is completed, continue to keep warm for reaction;

[0017] B. Sampling and testing. When the contents of free chlorophenylmethyldichlorosilane and dimethyldichlorosilane monomers are both lower than 0.5%, it indicates that the chain extension polymerization of the organosilicon monomer is basically completed. At this time, the by-product ethylenediamine hydrochloride solid is removed by vacuum filtration. The obtained filtrate is heated to 125-130° C., and the toluene solvent and the residual very small amount of ethylenediamine are removed during the heating process;

[0018] C. When the toluene content is less than 2%, add the catalyst 2 and the silicon-containing chain extender 3-tert-butyldimethylsilyloxyglutaric anhydride in the formula amount to carry out chain extension reaction, and gradually increase the temperature to 200-210° C. at a heating rate of 20-25° C. / h, and keep the temperature to carry out chain extension reaction; take samples for testing, and when the acid value of the polymer reaches 40-48 mgKOH / g, add the neopentyl glycol in the formula amount, and increase the temperature to 225-230° C. to carry out chain extension reaction;

[0019] D. Take samples for testing. When the acid value of the polymer reaches 25-32 mgKOH / g, add the mixture of antioxidant 1076 and antioxidant 168. After stirring evenly, start the vacuum system, control the vacuum degree at -0.097 to -0.099 MPa, and continue the vacuum polycondensation reaction at 225-230°C.

[0020] E. When the acid value of the reactant reaches 10-15 mgKOH / g, release the vacuum, add 2-ethyl-2-methylsuccinic acid, and continue to carry out the end-capping reaction at 225-230°C until the acid value of the polymer reaches 22-27 mgKOH / g, stop the reaction, discharge the material while hot, cool the polyester resin with a steel belt with condensed water, and then crush and granulate it to obtain the polyester resin.

[0021] The obtained product has the appearance of colorless and transparent particles, an acid value of 22-27 mgKOH / g, and a softening point of 100-107°C.

[0022] The use of the polyester resin for high-temperature resistant and high-leveling HAA powder coating as described above or the high-temperature resistant and high-leveling HAA powder coating obtained by the preparation method in the HAA powder coating system.

[0023] The HAA powder coating formula includes the prepared polyester resin, HAA, titanium dioxide, barium sulfate, a brightener, a leveling agent, benzoin and the like.

[0024] As described above, the preparation method of the coating comprises: mixing the materials, extruding, tableting and crushing with a twin-screw extruder, and then crushing and sieving the tablets to form a powder coating; the powder coating is sprayed on the surface-treated tinplate substrate with an electrostatic spray gun, and the coating is obtained after curing.

[0025] Beneficial effects:

[0026] The polyester resin for HAA powder coating with high temperature resistance and high leveling of the present invention is obtained by polymerization of raw materials including chlorophenylmethyldichlorosilane, dimethyldichlorosilane, 2-methyl-1,3-propanediol, 3-tert-butyldimethylsiloxyglutaric anhydride, neopentyl glycol, and 2-ethyl-2-methylsuccinic acid. A special copolymerized silicone segment structure with high temperature resistance and excellent lubricity is introduced into the polyester structure through reaction, and at the same time, the silicon-containing dibasic acid 3-tert-butyldimethylsiloxyglutaric anhydride and neopentyl glycol are copolymerized and grafted to extend the chain, and finally a flexible terminal carboxyl polyester resin with low activity is obtained by end-capping with a high steric hindrance flexible monomer 2-ethyl-2-methylsuccinic acid, so as to achieve the effect of slowing down the curing speed and increasing the leveling time. At the same time, due to the large amount of use of silicone copolymer segments, the high temperature resistance is good, and the segments of the polyester resin are soft and have good lubricity, a low softening point, and good fluidity during high temperature curing. The final acid value of the polyester resin is also low, and the amount of HAA curing agent required during curing is small. On the one hand, it reduces the cost of powder coatings, and on the other hand, it also reduces the water molecules generated during curing, thereby making the coating film after HAA curing resistant to high temperatures and having better leveling. In addition, due to the long curing time, it is conducive to the full escape of small molecule water, and the anti-pinhole effect of thick coating is obvious. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with embodiments. It should be noted that, in the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other. It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those generally understood by those of ordinary skill in the art to which this application belongs. The words "including" or "comprising" and the like used in the disclosure of the present invention mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0028] The raw materials described in the present invention are all commercially available.

[0029] Preparation Example 1

[0030] A polyester resin for high temperature resistant and high leveling HAA powder coating, the polyester resin comprising the following raw materials in molar proportions:

[0031]

[0032] Catalyst 1 is ethylenediamine, and the amount used is 12.5% ​​of the mass of dimethyldichlorosilane;

[0033] Catalyst 2 is tetrabutyl titanate, and the amount used is 1.3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride;

[0034] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168, the mass ratio of the two is 3:1, and the amount used is 3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride.

[0035] The method of producing a polyester resin comprises the following steps:

[0036] A. Add the formulated amount of toluene, 2-methyl-1,3-propanediol and catalyst 1 into a reaction kettle, heat to 50° C. and keep warm, then slowly dropwise add the formulated amount of a mixed solution of chlorophenylmethyldichlorosilane and dimethyldichlorosilane, while introducing nitrogen for bubbling to quickly lead the generated hydrogen chloride gas out of the reaction system, the dropping time is controlled at 2.5 h, and after the dropping is completed, continue to keep warm for reaction;

[0037] B. Sampling and testing. When the contents of free chlorophenylmethyldichlorosilane and dimethyldichlorosilane monomers are both lower than 0.5%, it indicates that the chain extension polymerization of the organosilicon monomer is basically completed. At this time, the by-product ethylenediamine hydrochloride is removed by vacuum filtration. The obtained filtrate is heated to 125° C. During the heating process, the toluene solvent and a very small amount of residual ethylenediamine are removed;

[0038] C. When the toluene content is less than 2%, add the catalyst 2 and the silicon-containing chain extender 3-tert-butyldimethylsilyloxyglutaric anhydride in the formula amount to carry out chain extension reaction, and gradually increase the temperature to 200° C. at a heating rate of 20° C. / h, and keep the temperature to carry out chain extension reaction; take samples for testing, and when the acid value of the polymer reaches 40-48 mgKOH / g, add the neopentyl glycol in the formula amount, and increase the temperature to 225° C. to carry out chain extension reaction;

[0039] D. Take samples for testing. When the acid value of the polymer reaches 25-32 mgKOH / g, add the mixture of antioxidant 1076 and antioxidant 168. After stirring evenly, start the vacuum system, control the vacuum degree at -0.099 MPa, and continue the vacuum polycondensation reaction at 225°C.

[0040] E. When the acid value of the reactant reaches 10-15 mgKOH / g, release the vacuum, add 2-ethyl-2-methylsuccinic acid, and continue to carry out the end-capping reaction at 225° C. until the acid value of the polymer reaches the expected value, stop the reaction, discharge the material while hot, cool the polyester resin with a steel belt with condensed water, and then crush and granulate it to obtain the polyester resin.

[0041] The acid value of the prepared polyester resin is 23 mgKOH / g and the softening point is 102°C.

[0042] Preparation Example 2

[0043] A polyester resin for high temperature resistant and high leveling HAA powder coating, the polyester resin comprising the following raw materials in molar proportions:

[0044]

[0045]

[0046] Catalyst 1 is ethylenediamine, and the amount used is 15% of the mass of dimethyldichlorosilane;

[0047] Catalyst 2 is tetrabutyl titanate, and the amount used is 1.3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride;

[0048] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168, the mass ratio of the two is 3:1, and the amount used is 3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride.

[0049] The preparation method is the same as that of Preparation Example 1.

[0050] The obtained product has the appearance of colorless and transparent particles, an acid value of 27 mgKOH / g, and a softening point of 103°C.

[0051] Preparation Example 3

[0052] A polyester resin for high temperature resistant and high leveling HAA powder coating, the polyester resin comprising the following raw materials in molar proportions:

[0053]

[0054] Catalyst 1 is ethylenediamine, and the amount used is 14% of the mass of dimethyldichlorosilane;

[0055] Catalyst 2 is tetrabutyl titanate, and the amount used is 1.3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride;

[0056] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168, the mass ratio of the two is 3:1, and the amount used is 2% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride.

[0057] The preparation method is the same as that of Preparation Example 1.

[0058] The obtained product has the appearance of colorless and transparent particles, an acid value of 25 mgKOH / g, and a softening point of 106°C.

[0059] Preparation Example 4

[0060] A polyester resin for high temperature resistant and high leveling HAA powder coating, the polyester resin comprising the following raw materials in molar proportions:

[0061]

[0062] Catalyst 1 is ethylenediamine, and the amount used is 10% of the mass of dimethyldichlorosilane;

[0063] Catalyst 2 is tetrabutyl titanate, and the amount used is 1% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride;

[0064] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168, the mass ratio of the two is 3:1, and the amount used is 2% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride.

[0065] The preparation method is the same as that of Preparation Example 1.

[0066] The obtained product has the appearance of colorless and transparent particles, an acid value of 26 mgKOH / g, and a softening point of 101°C.

[0067] Examples 1-4 (the polyester resins are obtained by Preparations 1-4, respectively):

[0068] Using HAA powder coating formula, the formula by mass is usually as follows:

[0069]

[0070] Comparative Example 1: The powder coating formulation described in Examples 1-4 above was used, except that a commercially available HAA system polyester resin was used, with an acid value of 33 mgKOH / g, a softening point of 118°C, model SJ4B, Anhui Shenjian New Materials Co., Ltd.

[0071] Comparative Example 2: The powder coating formulations described in Examples 1-4 above were used, and the other conditions were the same as those in Comparative Example 1, except that the amount of HAA in the powder coating formulation was increased from 21 g to 29 g.

[0072] Preparation of coating: Mix all materials according to the formula of HAA powder coating, extrude, tablet and crush with a twin-screw extruder, and then crush and sieve the tablets (160-180 mesh) to make powder coating. The powder coating is sprayed on the surface treated tinplate substrate with an electrostatic spray gun, and cured at 200℃ / 15min to obtain the coating.

[0073] The coating index test is based on GB / T 21776-2008 "Testing Standard Guide for Powder Coatings and Their Coatings". The leveling grade is based on the PCI grading method, 0-10, and the larger the number, the better the leveling. The performance comparison is shown in Table 1 and Table 2.

[0074] Table 1 Coating properties of examples and comparative examples (film thickness 80 μm)

[0075]

[0076] Table 2 Anti-thick coating pinhole performance of coating films of examples and comparative examples (90-130 μm)

[0077]

[0078] As can be seen from Table 1 and Table 2, the product of the present invention is a product obtained by graft copolymerization of special organic silicon raw materials with special diols and dibasic acids. It has a low acid value and is used in HAA powder coatings. The amount of HAA is small, and the coating film after curing at 200℃ / 15min has excellent leveling, high temperature resistance and anti-thick coating pinhole performance. The coating film has no pinholes in the film thickness of 80-110μm, and only very slight pinholes appear at 130μm. At the same time, the leveling grade of the coating film is 6 or above. After 300℃ / 10h and 300℃ / 50h, there is no obvious change on the surface of the coating film. Other aspects such as impact resistance and gloss meet the application requirements.

[0079] Comparative Example 1 and Comparative Example 2 use the same commercially available common polyester resin product. Due to the high acid value of the polyester resin used, the HAA curing agent in Comparative Example 1 is insufficient and cannot be fully cured, resulting in poor performance of the coating such as impact resistance, gloss, leveling, and high temperature resistance. Comparative Example 2 increases the HAA curing agent to a normal dosage, which can achieve full curing, but due to the insufficient lubricity and flexibility of the polyester segment, the leveling grade of the coating can only reach level 5, and without the introduction of high temperature resistant monomers, its high temperature resistance is slightly poor. The coating shows obvious yellowing under high temperature baking of 300℃ / 10h, and the yellowing is more serious at 300℃ / 50h. At the same time, the pinholes are extremely slight when the coating thickness is 80μm, but obvious pinholes appear when the coating thickness reaches 100μm, indicating that the anti-thick coating pinhole performance is poor, and it is significantly worse than the product of the present invention in terms of leveling, high temperature resistance and anti-thick coating pinholes.

[0080] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that, for those skilled in the art, the described embodiments can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the above description is illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A polyester resin for high temperature resistant and high leveling HAA powder coating, characterized in that: The polyester resin comprises the following raw materials in molar proportions: The raw materials also include catalyst 1, catalyst 2 and an antioxidant.

2. A polyester resin for high temperature resistant and high leveling HAA powder coating as claimed in claim 1, characterized in that: Catalyst 1 is ethylenediamine, and the amount used is 10-15% of the mass of dimethyldichlorosilane.

3. A polyester resin for high temperature resistant and high leveling HAA powder coating as claimed in claim 1, characterized in that: Catalyst 2 is tetrabutyl titanate, and the amount used is 1-1.3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride.

4. A polyester resin for high temperature resistant and high leveling HAA powder coating as claimed in claim 1, characterized in that: The antioxidant is a mixture of antioxidant 1076 and antioxidant 168, the mass ratio of the two is 3:1, and the dosage is 2-3% of the mass of 3-tert-butyldimethylsilyloxyglutaric anhydride.

5. A method for preparing a polyester resin for high temperature resistant and high leveling HAA powder coating according to any one of claims 1 to 4, characterized in that: The steps include: A. Add the formulated amount of toluene, 2-methyl-1,3-propanediol and catalyst 1 into a reaction kettle, start stirring and heat to 50-55° C. and then keep warm, then slowly dropwise add the formulated amount of a mixed solution of chlorophenylmethyldichlorosilane and dimethyldichlorosilane, and simultaneously introduce nitrogen for bubbling to quickly lead the generated hydrogen chloride gas out of the reaction system. After the dropwise addition is completed, continue to keep warm for reaction; B. Sampling and testing. When the contents of free chlorophenylmethyldichlorosilane and dimethyldichlorosilane monomers are both lower than 0.5%, it indicates that the chain extension polymerization of the organosilicon monomer is basically completed. At this time, the by-product ethylenediamine hydrochloride solid is removed by vacuum filtration. The obtained filtrate is heated to 125-130° C., and the toluene solvent and the residual very small amount of ethylenediamine are removed during the heating process; C. When the toluene content is less than 2%, add the catalyst 2 and the silicon-containing chain extender 3-tert-butyldimethylsilyloxyglutaric anhydride in the formula amount to carry out chain extension reaction, and gradually raise the temperature to 200-210° C. and keep the temperature to carry out chain extension reaction; take samples for testing, and when the acid value of the polymer reaches 40-48 mgKOH / g, add the neopentyl glycol in the formula amount, and raise the temperature to 225-230° C. to carry out chain extension reaction; D. Take samples for testing. When the acid value of the polymer reaches 25-32 mgKOH / g, add antioxidant, stir evenly, start the vacuum system, and continue the vacuum polycondensation reaction at 225-230°C; E. When the acid value of the reactant reaches 10-15 mgKOH / g, release the vacuum, add 2-ethyl-2-methylsuccinic acid, and continue to carry out the end-capping reaction at 225-230° C. until the acid value of the polymer reaches 22-27 mgKOH / g, stop the reaction, discharge the material while hot, cool the polyester resin, and then crush and granulate it to obtain the polyester resin.

6. A method for preparing a polyester resin for high temperature resistant and high leveling HAA powder coating according to claim 5, characterized in that: In step A, the dropping time is controlled at 2-2.5 h.

7. A method for preparing a polyester resin for high temperature resistant and high leveling HAA powder coating according to claim 5, characterized in that: In step C, the temperature is gradually increased to 200-210° C. at a heating rate of 20-25° C. / h.

8. The method for preparing a polyester resin for high temperature resistant and high leveling HAA powder coating according to claim 5, characterized in that: In step D, the vacuum degree is controlled at -0.097 to -0.099 MPa; in step E, the polyester resin is cooled by a steel belt with condensed water.

9. Use of the polyester resin for high-temperature resistant and high-leveling HAA powder coating as described in claims 1-4 or the high-temperature resistant and high-leveling HAA powder coating obtained by the preparation method according to claims 5-8 in a HAA powder coating system.

10. The use according to claim 9, characterized in that: The preparation method of the HAA powder coating system comprises: mixing various materials, extruding, tableting, and crushing with a twin-screw extruder, and then crushing and sieving the tablets to make powder coating; spraying the powder coating on the tinplate substrate after surface treatment with an electrostatic spray gun, and curing to obtain a coating.

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