A Low-Cost Universal Leveling Agent for Powder Coatings and Its Preparation Method

Abstract

The present invention relates to a low-cost general-purpose leveling agent for powder coatings, which is obtained by polymerizing raw materials including by-products of cyclohexanone oxime, toluene, acrylic acid, pivalic acid, butyl oleate, and n-butyl acrylate. This product is used as a general-purpose low-cost leveling agent, which can reduce costs and increase the added value of cyclohexanone oxime by-products while hardly reducing the application performance of the product, and has important economic and social value.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer compositions, and more specifically, to a low-cost general-purpose leveling agent for powder coatings and a preparation method thereof. Background Art

[0002] With the increasingly high requirements for VOC emissions in the coating field, the coatings in multiple fields have gradually shifted from paints to powder coatings. With the intensification of industry competition, the powder coating industry also has higher and higher requirements for costs. Although there are various types of powder coatings, no matter which variety of powder coatings, there are certain requirements for the surface leveling of coatings. Therefore, a general-purpose leveling agent is required. How to develop a general-purpose leveling agent product with good performance and low cost is also very important for industry competitiveness. Cyk, also known as tri(2-hydroxyethyl)isocyanuric acid, is an important raw material for heat-resistant insulating paints. It is obtained by the ring-opening reaction of isocyanuric acid and ethylene oxide. However, during the reaction process, in order to make the reaction proceed completely, part of the hydroxyl groups of tri(2-hydroxyethyl)isocyanuric acid often continue to undergo ring-opening polymerization with ethylene oxide, resulting in by-products. When the product is obtained through methanol crystallization treatment, a certain amount of by-products will be generated. Most enterprises burn or biochemically degrade them as waste, which not only wastes resources but also is not environmentally friendly. How to comprehensively utilize Cyk by-products has always been a difficult problem in the industry.

[0003] To address the above problems, the present invention designs and develops a low-cost general-purpose leveling agent product for powder coatings. This leveling agent is obtained by polymerizing raw materials including Cyk by-products, toluene, acrylic acid, pivalic acid, butyl oleate, and n-butyl acrylate. This product is used as a general-purpose low-cost leveling agent. While reducing costs and realizing the added value improvement of Cyk by-products, it hardly reduces the application performance of the product, and has important economic and social value. Summary of the Invention

[0004] To address the above problems, the present invention designs and develops a low-cost general-purpose leveling agent product for powder coatings. This leveling agent is obtained by polymerizing raw materials including Cyk by-products, toluene, acrylic acid, pivalic acid, butyl oleate, and n-butyl acrylate. This product is used as a general-purpose low-cost leveling agent. While reducing costs and realizing the added value improvement of Cyk by-products, it hardly reduces the application performance of the product, and has important economic and social value.

[0005] A low-cost general-purpose leveling agent for powder coatings, which comprises raw materials with the following mass parts:

[0006]

[0007] The raw materials also include catalyst 1, catalyst 2, and activated clay.

[0008] Among them, Catalyst 1 is tetraethyl titanate, and its dosage is 0.25 - 0.4% of the mass of acrylic acid; Catalyst 2 is benzoyl peroxide (BPO), and its dosage is 2 - 3% of the mass of n-butyl acrylate; the dosage of activated clay is 0.8 - 1.2% of the mass of the by-product of cyanuric acid tris(2-hydroxyethyl) ester, and the model is high decolorizing T-type activated clay (for example, it can be purchased from Qingdao Shengtai Silicon Industry Co., Ltd.); the by-product of cyanuric acid tris(2-hydroxyethyl) ester is a viscous liquid, which is a by-product of the production of cyanuric acid tris(2-hydroxyethyl) ester, and includes a methanol solution of a polymer formed by the overreaction of cyanuric acid tris(2-hydroxyethyl) ester and ethylene oxide, with a solid content of 85 - 90%, a hydroxyl value of 530 - 580 mgKOH / g, and a molecular structure of:

[0009]

[0010] (For example, the by-product of cyanuric acid tris(2-hydroxyethyl) ester can be purchased from Shandong Jianbang New Materials Co., Ltd.).

[0011] The preparation method of the low-cost general-purpose leveling agent for powder coatings described above includes the following steps:

[0012] A. Add the formulated amount of butyl oleate, n-butyl acrylate and Catalyst 2 into a premixing tank. After fully mixing evenly, pump it to a high-level tank for standby;

[0013] B. Add the formulated amount of the by-product of cyanuric acid tris(2-hydroxyethyl) ester and toluene into a reaction kettle. Start stirring and heat up to 50 - 55 °C to fully dissolve it. Then add the formulated amount of activated clay and stir for decolorization for 1 - 1.5 h, and then perform pressure filtration to obtain a clear and transparent filtrate and filter residue; the filtrate will be continuously used, and the filter residue will be treated as waste;

[0014] C. Pump the filtrate into a reaction kettle, gradually heat up to 100 - 105 °C, and simultaneously remove the residual low-boiling solvent methanol in the filtrate during the heating process. Then add the formulated amount of Catalyst 1 and acrylic acid, stir evenly, and heat up to the boiling point of toluene solvent for water-carrying esterification reaction;

[0015] D. Take samples for detection. When the acid value of the esterified product is lower than 3 mgKOH / g, it indicates that the grafting esterification reaction of acrylic acid and the by-product of cyanuric acid tris(2-hydroxyethyl) ester is basically completed. Then add the formulated amount of trimethylacetic acid and continue the water-carrying esterification reaction at the boiling point of toluene solvent to block other active hydroxyl groups in the by-product of cyanuric acid tris(2-hydroxyethyl) ester;

[0016] E. Take samples for detection. When the hydroxyl value of the esterified product is lower than 10 mgKOH / g, it indicates that the blocking of the remaining hydroxyl groups in the acrylic acid-grafted polymer of the by-product of cyanuric acid tris(2-hydroxyethyl) ester is basically completed. Cool down to 101 - 106 °C, then open the dropping valve of the high-level tank, drop the mixed solution prepared in step A, and then continue to keep the temperature at 101 - 106 °C for heat preservation reaction for 2 - 3 h;

[0017] F. Detect by gas chromatography for sampling. When the free n-butyl acrylate and butyl oleate in the polymer system are less than 1%, it indicates that the polymerization monomers have basically reacted completely. Start the vacuum system. While fully removing the toluene solvent, gradually raise the temperature to 135 - 140 °C and continue high-temperature and high-vacuum devolatilization to fully remove unreacted small-molecule compounds such as trimethylacetic acid. When the volatile content is less than 1%, stop the vacuum system and discharge the product at high temperature to obtain a low-cost general-purpose leveling agent.

[0018] Preferably, in step B, use a 350-mesh filter bag for pressure filtration to obtain a clear and transparent filtrate and filter residue; in step E, control the dropping to be completed within 2 - 2.5 h; in step F, control the vacuum degree at -0.097 to -0.099 Mpa.

[0019] For example, the preparation method of the low-cost general-purpose leveling agent for powder coatings includes the following steps:

[0020] A. Add the formulated amount of butyl oleate, n-butyl acrylate, and catalyst 2 to the premixing tank. After fully mixing evenly, pump it to the high-level tank for standby.

[0021] B. Add the formulated amount of by-product of cyclohexanone oxime and toluene to the reaction kettle. Start stirring and raise the temperature to 50 - 55 °C to fully dissolve it. Then add the formulated amount of activated clay and stir for decolorization for 1 - 1.5 h. Then use a 350-mesh filter bag for pressure filtration to obtain a clear and transparent filtrate and filter residue; the filtrate will be used continuously, and the filter residue will be treated as waste.

[0022] C. Pump the filtrate to the reaction kettle, gradually raise the temperature to 100 - 105 °C, and remove the residual low-boiling solvent methanol in the filtrate during the heating process. Then add the formulated amount of catalyst 1 and acrylic acid, stir evenly, and raise the temperature to the boiling point of the toluene solvent for water-carrying esterification reaction.

[0023] D. Sample and detect. When the acid value of the esterified product is less than 3 mg KOH / g, it indicates that the grafting esterification reaction of acrylic acid and the by-product of cyclohexanone oxime is basically completed. Then add the formulated amount of trimethylacetic acid and continue the water-carrying esterification reaction at the boiling point of the toluene solvent to block other active hydroxyl groups in the by-product of cyclohexanone oxime.

[0024] E. Sample and detect. When the hydroxyl value of the esterified product is less than 10 mg KOH / g, it indicates that the blocking of the remaining hydroxyl groups in the acrylic acid-grafted polymer of the by-product of cyclohexanone oxime is basically completed. Cool down to 101 - 106 °C, then open the dropping valve of the high-level tank, drop the mixed solution prepared in step A, control the dropping to be completed within 2 - 2.5 h, and then continue to keep the temperature at 101 - 106 °C for heat preservation reaction for 2 - 3 h.

[0025] F. Take samples and test them by gas chromatography. When the free n-butyl acrylate and butyl oleate in the polymer system are less than 1%, it means that the polymerization monomers have basically reacted. Start the vacuum system to fully remove the toluene solvent, and gradually increase the temperature to 135-140°C to continue high-temperature and high-vacuum devolatilization to fully remove unreacted small molecular compounds such as trimethylacetic acid. The vacuum degree is controlled at -0.097 to -0.099Mpa. When the volatile matter is less than 1%, stop the vacuum system and discharge the material at high temperature to obtain a low-cost universal leveling agent.

[0026] The obtained product has the appearance of light yellow viscous liquid.

[0027] Application of the low-cost universal leveling agent for powder coatings as described above or the low-cost universal leveling agent for powder coatings obtained by the preparation method in powder coatings.

[0028] As described above, the powder coating can be a TGIC universal powder coating or a mixed 70 / 30 universal powder coating.

[0029] According to the powder coating formula, the materials are mixed evenly, extruded, tableted and crushed by a twin-screw extruder, and then the tablets are crushed and sieved to form powder coating. The powder coating is sprayed on the tinplate by an electrostatic spray gun and solidified to obtain the coating.

[0030] Beneficial effects:

[0031] The invention relates to a low-cost leveling agent for powder coatings, which is obtained by polymerizing raw materials including cyc byproduct, toluene, acrylic acid, trimethylacetic acid, butyl oleate and n-butyl acrylate. The cyc byproduct has good viscosity and a lighter color after being treated, and currently has low added value. After being refined, it is partially grafted with acrylic acid, and then other hydroxyl groups are completely capped with trimethylacetic acid with large steric hindrance and hydrophobicity to obtain a modified intermediate. The trimethyl group with large steric hindrance has a certain hydrophobic protection ability for the formed ester bond. The intermediate is then polymerized with butyl oleate and n-butyl acrylate to obtain the intermediate. The catalyst tetraethyl titanate not only has the effect of catalytic esterification modification, but also can improve the adhesion between the coating film and the metal substrate. The introduction of butyl oleate introduces a long alkyl chain into the polymerization chain, which further improves the hydrophobic ability of the leveling agent. Moreover, its cost is much lower than that of n-butyl acrylate, which has the function of further reducing the cost. This product is used as a general-purpose low-cost leveling agent. While reducing costs and increasing the added value of CYC by-products, it hardly reduces the application performance of the product and has important economic and social value. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present application and the technical features in the embodiments may be combined with each other. It should be pointed out that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs. As used in the disclosure of the present invention, words such as "including" or "comprising" and the like are intended to mean that the elements or items appearing before the word cover the elements or items listed after the word and their equivalents, without excluding other elements or items.

[0033] All raw materials described in the present invention are commercially available. For example, the activated clay model is high decolorization T-type activated clay (purchased from Qingdao Shengtai Silicon Industry Co., Ltd.); the by-product of CYMEL is a viscous liquid, which is a by-product of the production of CYMEL (trihydroxyethyl isocyanurate), including a methanol solution of a polymer formed by the overreaction of trihydroxyethyl isocyanurate and ethylene oxide, with a solid content of 85-90% and a hydroxyl value of 530-580 mgKOH / g, and the molecular structure is:

[0034]

[0035] (purchased from Shandong Jianbang New Materials Co., Ltd.).

[0036] Preparation Example 1

[0037] A low-cost general-purpose leveling agent for powder coatings, which comprises raw materials with the following mass parts:

[0038]

[0039] Catalyst 1 is tetraethyl titanate, and its dosage is 0.4% of the mass of acrylic acid; Catalyst 2 is benzoyl peroxide (BPO), and its dosage is 3% of the mass of butyl acrylate; the dosage of activated clay is 1.2% of the mass of the CYMEL by-product.

[0040] The preparation method of the low-cost general-purpose leveling agent for powder coatings comprises the following steps:

[0041] A. Add the formulated amount of butyl oleate, butyl acrylate and Catalyst 2 into a premixing tank, fully mix them evenly, and then pump them into a high-level tank for standby;

[0042] B. Add the formulated amount of the CYMEL by-product and toluene into a reaction kettle, start stirring and heat up to 55°C to fully dissolve it, then add the formulated amount of activated clay and stir for decolorization for 1.5 h, and then perform pressure filtration treatment with a 350-mesh filter bag to obtain a clear and transparent filtrate and filter residue; the filtrate will be used continuously, and the filter residue will be treated as waste;

[0043] C. Pump the filtrate into the reaction kettle, gradually raise the temperature to 105 °C. During the heating process, simultaneously remove the residual low-boiling solvent methanol in the filtrate. Then add the formulated amount of catalyst 1 and acrylic acid. After stirring evenly, raise the temperature to the boiling point of the toluene solvent for water-carrying esterification reaction;

[0044] D. Take samples for detection. When the acid value of the esterified product is lower than 3 mg KOH / g, it indicates that the grafting esterification reaction between acrylic acid and the by-product of sec is basically completed. Then add the formulated amount of trimethylacetic acid and continue the water-carrying esterification reaction at the boiling point of the toluene solvent to block other active hydroxyl groups in the by-product of sec;

[0045] E. Take samples for detection. When the hydroxyl value of the esterified product is lower than 10 mg KOH / g, it indicates that the blocking of the remaining hydroxyl groups in the acrylic acid-grafted polymer of the sec by-product is basically completed. Cool down to 106 °C, then open the dropping valve of the high-level tank and drop the mixed solution prepared in step A. Control the dropping to be completed within 2.5 h, and then continue to hold the reaction at 106 °C for 3 h;

[0046] F. Take samples and detect by gas chromatography. When the free n-butyl acrylate and butyl oleate in the polymer system are lower than 1%, it indicates that the polymerization monomers have basically reacted. Start the vacuum system to fully remove the toluene solvent while gradually raising the temperature to 140 °C and continue high-temperature high-vacuum devolatilization to fully remove unreacted small-molecule compounds such as trimethylacetic acid. Control the vacuum degree at -0.099 Mpa. When the volatile content is lower than 1%, stop the vacuum system and discharge at high temperature to obtain a low-cost general-purpose leveling agent.

[0047] Preparation Example 2

[0048] A low-cost general-purpose leveling agent for powder coatings, which comprises raw materials with the following mass parts:

[0049]

[0050] Catalyst 1 is tetraethyl titanate, and the dosage is 0.4% of the mass of acrylic acid; Catalyst 2 is benzoyl peroxide (BPO), and the dosage is 3% of the mass of n-butyl acrylate; The dosage of activated clay is 1.2% of the mass of the sec by-product.

[0051] The preparation method is the same as that of Example 1.

[0052] Preparation Example 3

[0053] A low-cost general-purpose leveling agent for powder coatings, which comprises raw materials with the following mass parts:

[0054]

[0055]

[0056] Catalyst 1 is tetraethyl titanate, and its dosage is 0.3% of the mass of acrylic acid; Catalyst 2 is benzoyl peroxide (BPO), and its dosage is 3% of the mass of n-butyl acrylate; the dosage of activated clay is 1% of the mass of the by-products of sike.

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

[0058] Preparation Example 4

[0059] A low-cost general-purpose leveling agent for powder coatings, which comprises raw materials with the following mass parts:

[0060]

[0061] Catalyst 1 is tetraethyl titanate, and its dosage is 0.25% of the mass of acrylic acid; Catalyst 2 is benzoyl peroxide (BPO), and its dosage is 2% of the mass of n-butyl acrylate; the dosage of activated clay is 0.8% of the mass of the by-products of sike.

[0062] The preparation method is the same as that of Example 1.

[0063] Comparative Preparation Example 1: A commercially available general-purpose leveling agent product is used as Comparative Example 1, model BLP402, Ningbo Nanhai Chemical Co., Ltd.

[0064] Examples 1-8 and Comparative Examples 1 and 2

[0065] Examples 1-4 and Comparative Example 1 are as follows: The leveling agents described in Preparation Examples 1-4 and Comparative Preparation Example 1 are respectively applied to the existing TGIC general-purpose powder coating formula to verify the performance of the general-purpose leveling agent; Examples 5-8 and Comparative Example 2 are as follows: The leveling agents described in Preparation Examples 1-4 and Comparative Preparation Example 1 are respectively applied to the existing mixed 70 / 30 general-purpose powder coating formula to verify the performance of the general-purpose leveling agent.

[0066] The formula is shown in Table 1 by weight:

[0067] Table 1 Existing TGIC general-purpose powder coating formula and mixed 70 / 30 general-purpose powder coating formula

[0068] Formulation raw materials 70 / 30 general-purpose powder coating TGIC general-purpose powder coating E-12 epoxy resin 180 parts 70 / 30 polyester resin 420 parts TGIC-type polyester resin 558 parts TGIC curing agent 42 parts Titanium dioxide 180 parts 180 parts Barium sulfate 160 parts 160 parts Leveling agent 10 parts 10 parts Brightening agent 10 parts 10 parts Benzoin 4 parts 4 parts

[0069] Among them, the 70 / 30 polyester resin uses the general-purpose 70 / 30 polyester resin of Anhui Shenjian New Materials Co., Ltd., model SJ7411. The TGIC type polyester resin uses the general-purpose TGIC polyester resin of Anhui Shenjian New Materials Co., Ltd., model SJ9000. Other raw materials are all ordinary industrial products.

[0070] Preparation of coating: Mix all materials according to the above powder coating formula, extrude, tablet and crush with a twin-screw extruder, and then crush and sieve the tablets to make powder coating. The powder coating is sprayed on the tinplate with an electrostatic spray gun, with a film thickness of about 80μm, and cured at 200℃ / 10min to obtain the coating.

[0071] The coating index test is based on GB / T 21776-2008 "Guide to the Testing Standards of Powder Coatings and Their Coatings" and the leveling grade test is based on JB-T 3998-1999 "Scrape-coat Test Method for Leveling of Coatings".

[0072] Table 2 Coating properties of Examples 1-4 and Comparative Example 1 in TGIC general-purpose powder coating

[0073]

[0074] Table 3 Coating properties of Examples 5-8 and Comparative Example 2 in mixed 70 / 30 general-purpose powder coatings

[0075]

[0076] It can be seen that the product of the present invention is prepared by grafting and modifying the by-product of CYC with acrylic acid and trimethylacetic acid to obtain an intermediate, and then preparing it with butyl oleate and n-butyl acrylate by means of a polymerization process. The final product has good hydrophobicity and is used in TGIC universal powder coatings or 70 / 30 mixed universal powder coatings respectively. It can pass the surface performance, gloss and curing impact resistance smoothly, and is not much different from the ordinary pure acrylic ester system leveling agent on the market in terms of leveling grade and boiling water boiling, and is slightly better than the ordinary universal leveling agent products on the market in the 70 / 30 system.

[0077] The product of the present invention not only uses low-cost raw materials butyl oleate and CYC by-products to reduce the cost of the product's universal leveling agent and improve its hydrophobic performance, but more importantly, it realizes the comprehensive utilization of CYC by-products in the field of leveling agents, turning waste into treasure, and has strong economic and social benefits.

[0078] 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 low-cost general-purpose leveling agent for powder coatings, characterized in that, It comprises raw materials with the following parts by mass: 8 - 10 parts of sec-byproduct; 20 - 25 parts of toluene; 2 - 3 parts of acrylic acid; 7 - 9 parts of pivalic acid; 2 - 3 parts of butyl oleate; 20 - 26 parts of n-butyl acrylate; The raw materials also include catalyst 1, catalyst 2 and activated clay; The sec-byproduct includes a methanol solution of a polymer formed by the overreaction of trihydroxyethyl isocyanurate and ethylene oxide, with a solid content of 85 - 90% and a hydroxyl value of 530 - 580 mgKOH / g, and the molecular structure is: ； The preparation method of the low-cost general-purpose leveling agent for powder coatings comprises the following steps: A. Add the formulated amounts of butyl oleate, n-butyl acrylate and catalyst 2 into a premixing tank, mix them evenly, and then pump them into a high-level tank for standby; B. Add the formulated amounts of sec-byproduct and toluene into a reaction kettle, start stirring and heat up to 50 - 55°C to dissolve them fully, then add the formulated amount of activated clay and stir for decolorization for 1 - 1.5 h, and then perform pressure filtration to obtain a clear and transparent filtrate and filter residue; the filtrate will be used continuously, and the filter residue will be treated as waste; C. Pump the filtrate into the reaction kettle, gradually heat up to 100 - 105°C, and simultaneously remove the residual low-boiling solvent methanol in the filtrate during the heating process, then add the formulated amount of catalyst 1 and acrylic acid, stir evenly, and heat up to the boiling point of toluene solvent for water-carrying esterification reaction; D. Take samples for detection. When the acid value of the esterified product is lower than 3 mgKOH / g, it indicates that the grafting esterification reaction of acrylic acid and sec-byproduct is basically completed, then add the formulated amount of pivalic acid, and continue the water-carrying esterification reaction at the boiling point of toluene solvent to block other active hydroxyl groups in the sec-byproduct; E. Take samples for detection. When the hydroxyl value of the esterified product is lower than 10 mgKOH / g, it indicates that the blocking of the remaining hydroxyl groups in the acrylic acid graft polymer of sec-byproduct is basically completed. Cool down to 101 - 106°C, then open the dropping valve of the high-level tank, drop the mixed solution prepared in step A, and then continue to keep the temperature at 101 - 106°C for heat preservation reaction for 2 - 3 h; F. Take samples and detect them by gas chromatography. When the free n-butyl acrylate and butyl oleate in the polymer system are lower than 1%, start the vacuum system to fully remove the toluene solvent while gradually heating up to 135 - 140°C to continue high-temperature and high-vacuum devolatilization. When the volatile matter is lower than 1%, stop the vacuum system and discharge the product at high temperature to obtain the low-cost general-purpose leveling agent.

2. The low-cost general-purpose leveling agent for powder coatings according to claim 1, wherein Catalyst 1 is tetraethyl titanate, and its dosage is 0.25 - 0.4% of the mass of acrylic acid.

3. The low-cost general-purpose leveling agent for powder coatings according to claim 1, wherein Catalyst 2 is benzoyl peroxide (BPO), and its dosage is 2 - 3% of the mass of n-butyl acrylate.

4. The low-cost general-purpose leveling agent for powder coatings according to claim 1, wherein The dosage of activated clay is 0.8 - 1.2% of the mass of sec-byproduct, and the model is high-decolorization T-type activated clay.

5. The preparation method of a low-cost general-purpose leveling agent for powder coatings according to any one of claims 1-4, characterized in that, The preparation method comprises the following steps: A. Add the formulated amounts of butyl oleate, n-butyl acrylate and catalyst 2 into a premixing tank, mix them evenly, and then pump them into a high-level tank for standby; B. Add the formulated amount of sec-byproduct and toluene into the reaction kettle, start stirring and heat up to 50 - 55 °C to fully dissolve them. Then add the formulated amount of activated clay and stir for decolorization for 1 - 1.5 h. Then perform pressure filtration to obtain clear and transparent filtrate and filter residue; the filtrate will be further utilized, and the filter residue will be treated as waste. C. Pump the filtrate into the reaction kettle, gradually heat up to 100 - 105 °C. During the heating process, simultaneously remove the residual low-boiling solvent methanol in the filtrate. Then add the formulated amount of catalyst 1 and acrylic acid, stir evenly, and then heat up to the boiling point of toluene solvent for water-carrying esterification reaction. D. Take samples for detection. When the acid value of the esterified product is lower than 3 mgKOH / g, it indicates that the grafting esterification reaction of acrylic acid and sec-byproduct is basically completed. Then add the formulated amount of trimethylacetic acid and continue the water-carrying esterification reaction at the boiling point of toluene solvent to block other active hydroxyl groups in the sec-byproduct. E. Take samples for detection. When the hydroxyl value of the esterified product is lower than 10 mgKOH / g, it indicates that the blocking of the remaining hydroxyl groups in the acrylic acid graft polymer of sec-byproduct is basically completed. Cool down to 101 - 106 °C, then open the dropping valve of the high-level tank, drop the mixed solution prepared in step A, and then continue to keep the temperature at 101 - 106 °C for heat preservation reaction for 2 - 3 h. F. Take samples and detect with gas chromatography. When the free n-butyl acrylate and butyl oleate in the polymer system are lower than 1%, start the vacuum system to fully remove the toluene solvent while gradually heating up to 135 - 140 °C to continue high-temperature and high-vacuum devolatilization. When the volatile content is lower than 1%, stop the vacuum system and discharge the product at high temperature to obtain a low-cost general-purpose leveling agent.

6. The preparation method of a low-cost general-purpose leveling agent for powder coatings according to claim 5, characterized in that, In step B, use a 350-mesh filter bag for pressure filtration to obtain clear and transparent filtrate and filter residue.

7. The preparation method of a low-cost general-purpose leveling agent for powder coatings as described in claim 5, characterized in that In step E, control the dropping to be completed within 2 - 2.5 h; in step F, control the vacuum degree to be -0.097 to -0.099 Mpa.

8. The application of a low-cost general-purpose leveling agent for powder coatings as described in any one of claims 1 - 4 or a low-cost general-purpose leveling agent for powder coatings obtained by the preparation method as described in any one of claims 5 - 7 in powder coatings.

9. The application as described in claim 8, wherein the powder coating is a TGIC general-purpose powder coating or a mixed 70 / 30 general-purpose powder coating.

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