Low-temperature curing thin-coat powder coating and preparation method therefor

Abstract

The present invention relates to the field of coating preparation. Disclosed are a low-temperature curing thin-coat powder coating and a preparation method therefor. The powder coating comprises a resin, an accelerant, a curing agent, a dispersing agent, benzoin, barium sulfate, a leveling agent, a brightening agent, and a pigment as preparation raw materials, and the preparation raw materials of the resin comprise neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid, isophthalic acid, a catalyst, and an antioxidant. In the present application, by optimizing the preparation raw materials of the resin and the preparation raw material proportion, the branching degree and the terminal carboxyl activity of the resin are effectively improved, the reaction activity of the resin is ensured, the curing temperature of the powder coating is reduced, and excellent weather resistance and mechanical properties can also be obtained; moreover, the catalyst and the antioxidant are added in the resin preparation stage, thereby facilitating improvement of the storage stability, solving, taken as a whole, the problem of non-uniform dispersion of powder coatings, and facilitating improvement of the glossiness of the coating and the performance of the coating.

Description

Low-temperature curing thin-coat powder coating and preparation method thereof Technical Field

[0001] The present invention relates to the field of coating preparation, in particular to a low-temperature curing thin-coat powder coating and a preparation method thereof. Background Art

[0002] Compared to traditional organic solvent coatings, powder coatings are favored for their safety, environmental friendliness, easy control of film thickness, and high coating efficiency. Powder coatings can be categorized into thermoplastic and thermosetting powder coatings based on resin properties. Thermoplastic powder coatings do not require a curing agent and produce films with excellent chemical resistance, toughness, flexibility, and mechanical strength, making them suitable for thick film applications. However, their adhesion to metal substrates is poor, typically requiring a primer or modified resin. Thermoplastic resins used in powder coatings include polyethylene, polyvinyl chloride, polypropylene, polyamide, and thermoplastic polyester. Thermosetting powder coatings require a curing agent. Thermosetting resins melt when heated and, when heated to a certain temperature, undergo a chemical cross-linking reaction with the curing agent, forming a film with defined mechanical properties. There are three main types of thermosetting powder coatings: polyester / epoxy hybrid powder coatings, epoxy powder coatings, and pure polyester powder coatings. Prior art methods increase the activity of powder coatings to achieve low-temperature curing by adding curing accelerators or employing more reactive functional groups in the base material. However, these methods also present the following challenges: Low-temperature curing powder coatings exhibit poor physical, mechanical, and chemical stability, and are particularly susceptible to fusing, sintering, or agglomeration after prolonged exposure to heat. Similarly, if a powder coating contains a curing agent that reacts below 170°C, prolonged exposure to heat can degrade its chemical stability. Curing can occur during storage, even before the coating film has formed, leading to pre-crosslinking. This can make leveling difficult or even impossible during curing, resulting in an "orange peel" or rough texture. Consequently, the reduced physical and mechanical stability of powder coatings leads to significant issues with performance, application, and appearance, while degraded chemical properties can lead to serious quality issues. In addition, the curing temperature of existing powder coatings is mostly 190°C to 200°C, which not only leads to: ① higher energy consumption during the curing process than liquid coatings, but also ② limits the application of powder coatings on temperature-sensitive materials (materials that are not heat-resistant). Therefore, some powder coating manufacturers on the market have developed low-temperature curing powder coatings. That is, by using low-temperature curing resins with higher reactivity or adding reaction catalysts, the powder coating can be cured at lower temperatures (<170°C). However, the addition of accelerators to low-temperature curing powder coatings also has problems with uneven dispersion, coating gloss, and performance degradation. In addition, existing technologies rarely improve the performance of powder coatings by improving the particle size, and the particle size of powder coatings can also affect the overall fluidity and coating quality of powder coatings. Summary of the Invention

[0003] Based on this, in order to solve the problems of poor quality, uneven dispersion, coating gloss and performance degradation of low-temperature curing thin-coat powder coatings in the prior art, the present invention provides a low-temperature curing thin-coat powder coating and a preparation method thereof. The specific technical solutions are as follows:

[0004] A low-temperature curing thin-coat powder coating, comprising the following raw materials in parts by weight: 45 to 55 parts of resin, 1 to 3 parts of accelerator, 3 to 9 parts of curing agent, 0.5 to 1 part of dispersant, 3 to 7 parts of benzoin, 15 to 20 parts of barium sulfate, 1 to 5 parts of leveling agent, 1 to 7 parts of brightener, and 7 to 9 parts of pigment;

[0005] The raw materials for preparing the resin include neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid, isophthalic acid, a catalyst and an antioxidant. In terms of mass ratio, the ratio of the neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid and isophthalic acid is (1-3): (1-4): (1-5): (3-7): (1-3): (2-5), the added amount of the catalyst accounts for 0.05% to 1% of the mass percentage of the resin, and the antioxidant accounts for 0.1% to 7% of the mass percentage of the resin.

[0006] The promoter is a nano-scale low-temperature promoter with fumed silica as a carrier.

[0007] Furthermore, the catalyst is monobutyltin oxide.

[0008] Furthermore, the antioxidant is obtained by mixing pentaerythritol dioctadecyl diphosphite and trimellitic anhydride in a mass ratio of (1-3): (2-5).

[0009] Furthermore, the preparation method of the resin is:

[0010] Neopentyl glycol, ethylene glycol and 1,4-cyclohexanedimethanol were mixed, water was added, and the mixture was heated to 75° C. to 85° C. at 25 rpm to 50 rpm to obtain a mixture;

[0011] Continue to add terephthalic acid, adipic acid, isophthalic acid and catalyst to the mixture, adjust to 100r / min~200r / min, continue to heat to 200℃~220℃, maintain for 20min~30min, then add antioxidant, continue stirring for 10min~20min, cool to 180℃~200℃, continue to reflux for 40min~60min, connect condensed water, and obtain resin after the reaction is completed.

[0012] Furthermore, the acid value of the resin is 25 mg / KOH / g to 70 mg / KOH / g.

[0013] Furthermore, the nano-scale low-temperature accelerator is a mixture of a polyester low-temperature accelerator and an ultra-low-temperature epoxy curing accelerator, or a polyester low-temperature curing accelerator.

[0014] Furthermore, the curing agent is β-hydroxyalkylamide.

[0015] Furthermore, the dispersant is a mixture of one or more of VOK-DS330 dispersant, VOK-DS360 dispersant, VOK-DS361 dispersant, VOK-DS363 dispersant, VOK-DS6203 dispersant, and VOK-DS6904 dispersant.

[0016] Furthermore, the leveling agent is an acrylate leveling agent.

[0017] In addition, the present application also provides a method for preparing a low-temperature curing thin-coat powder coating, the preparation method comprising the following steps:

[0018] The resin, accelerator, curing agent, dispersant, benzoin, barium sulfate, leveling agent, brightener and pigment are fully mixed and extruded through a twin-screw extruder, and then subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coating powder coating.

[0019] The above scheme effectively improves the branching degree and terminal carboxyl activity of the resin by optimizing the raw materials and the ratio of the raw materials for preparing the resin. While ensuring the reaction activity of the resin, it reduces the curing temperature of the powder coating and can also obtain excellent weather resistance and mechanical properties. The addition of catalysts and antioxidants in the resin preparation stage helps to improve storage stability. The interaction of the nano-scale low-temperature accelerator and dispersant using the resin and fumed silica as carriers can help reduce the problem of uneven dispersion of the powder coating when forming the coating, and help to improve the gloss and performance of the coating. When achieving thin coating, it avoids the problems of poor fluidity of the powder coating and coating gravel, and can achieve low-temperature curing of thin coating as a whole. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] A low-temperature curing thin-coat powder coating according to one embodiment of the present invention comprises the following raw materials in parts by weight: 45 to 55 parts of resin, 1 to 3 parts of accelerator, 3 to 9 parts of curing agent, 0.5 to 1 part of dispersant, 3 to 7 parts of benzoin, 15 to 20 parts of barium sulfate, 1 to 5 parts of leveling agent, 1 to 7 parts of brightener, and 7 to 9 parts of pigment.

[0023] The raw materials for preparing the resin include neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid, isophthalic acid, a catalyst and an antioxidant. In terms of mass ratio, the ratio of the neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid and isophthalic acid is (1-3): (1-4): (1-5): (3-7): (1-3): (2-5), the added amount of the catalyst accounts for 0.05% to 1% of the mass percentage of the resin, and the antioxidant accounts for 0.1% to 7% of the mass percentage of the resin.

[0024] The promoter is a nano-scale low-temperature promoter with fumed silica as a carrier.

[0025] In one embodiment, the catalyst is monobutyltin oxide.

[0026] In one embodiment, the antioxidant is a mixture of pentaerythritol dioctadecyl diphosphite and trimellitic anhydride in a mass ratio of (1-3): (2-5).

[0027] In one embodiment, the resin is prepared by:

[0028] Neopentyl glycol, ethylene glycol and 1,4-cyclohexanedimethanol were mixed, water was added, and the mixture was heated to 75° C. to 85° C. at 25 rpm to 50 rpm to obtain a mixture;

[0029] Continue to add terephthalic acid, adipic acid, isophthalic acid and catalyst to the mixture, adjust to 100r / min~200r / min, continue to heat to 200℃~220℃, maintain for 20min~30min, then add antioxidant, continue stirring for 10min~20min, cool to 180℃~200℃, continue to reflux for 40min~60min, connect condensed water, and obtain resin after the reaction is completed.

[0030] In one embodiment, the acid value of the resin is 25 mg / KOH / g to 70 mg / KOH / g.

[0031] In one embodiment, the molecular weight of the resin is 2000-3000.

[0032] In one embodiment, the nanoscale low-temperature accelerator is a mixture of a polyester low-temperature accelerator and an ultra-low-temperature epoxy curing accelerator or a polyester low-temperature curing accelerator. The polyester low-temperature curing accelerator is preferably TE-230; the ultra-low-temperature epoxy curing accelerator is preferably JT-6015A.

[0033] In one embodiment, the curing agent is β-hydroxyalkylamide.

[0034] In one embodiment, the dispersant is a mixture of one or more of VOK-DS330 dispersant, VOK-DS360 dispersant, VOK-DS361 dispersant, VOK-DS363 dispersant, VOK-DS6203 dispersant, and VOK-DS6904 dispersant.

[0035] In one embodiment, the leveling agent is an acrylate leveling agent.

[0036] In one embodiment, the brightener is one of acrylate copolymer and 701B brightener.

[0037] In one embodiment, the pigment is a mixture of one or more of titanium dioxide, titanium oxide, and calcium carbonate.

[0038] In addition, the present application also provides a method for preparing a low-temperature curing thin-coat powder coating, the preparation method comprising the following steps:

[0039] The resin, accelerator, curing agent, dispersant, benzoin, barium sulfate, leveling agent, brightener and pigment are fully mixed and extruded through a twin-screw extruder, and then subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coating powder coating.

[0040] In one embodiment, the temperature of the front zone of the twin-screw extruder is set to 115° C. to 120° C., the temperature of the rear zone is set to 100° C. to 105° C., and the rotation speed of the twin screw is set to 30 r / min to 35 r / min.

[0041] In one embodiment, the average particle size of the low-temperature curing thin-coat powder coating is 10 μm to 40 μm.

[0042] In one embodiment, the average particle size of the low temperature curing thin coating powder coating meets the following conditions: 50 <25μm, D 10 >11μm, D 90 <40μm. By narrowing the particle size distribution of powder coating, it is beneficial to apply thin coating and avoid the problem of poor fluidity of powder coating and grit on the coating surface caused by particle size reduction.50 It also narrows the particle size distribution of powder coatings, helps to achieve thin coating of low-temperature curing powder coatings, reduces the heat absorption of powder coatings, helps to further reduce curing time / lower curing temperature, and also helps to reduce the amount of powder coatings used and reduce the ingredients used.

[0043] The above scheme effectively improves the branching degree and terminal carboxyl activity of the resin by optimizing the raw materials and the ratio of the raw materials for preparing the resin. While ensuring the reaction activity of the resin, it reduces the curing temperature of the powder coating and can also obtain excellent weather resistance and mechanical properties. The addition of catalysts and antioxidants in the resin preparation stage helps to improve storage stability. The interaction of the nano-scale low-temperature accelerator and dispersant using the resin and fumed silica as carriers can help reduce the problem of uneven dispersion of the powder coating when forming the coating, and help to improve the gloss and performance of the coating. When achieving thin coating, it avoids the problems of poor fluidity of the powder coating and coating gravel, and can achieve low-temperature curing of thin coating as a whole.

[0044] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0045] Example 1:

[0046] A method for preparing a low-temperature curing thin-coat powder coating comprises the following steps:

[0047] Neopentyl glycol, ethylene glycol, and 1,4-cyclohexanedimethanol were mixed in a mass ratio of 3:4:5, water was added, and the mixture was heated to 75° C. at 50 r / min to obtain a mixture;

[0048] Continuing to add terephthalic acid, adipic acid, and isophthalic acid in a mass ratio of 7:3:5 to the mixture, and adding 1% of monobutyltin oxide based on the mass percentage of the resin, adjusting the temperature to 100 r / min, continuing to heat to 200° C., maintaining for 20 minutes, and then adding 3% of an antioxidant based on the mass percentage of the resin, wherein the antioxidant is a mixture of pentaerythritol dioctadecyl diphosphite and trimellitic anhydride in a mass ratio of 3:5, continuing to stir for 20 minutes, cooling to 180° C., continuing to reflux for 40 minutes, connecting condensed water, and obtaining a resin after the reaction is completed;

[0049] According to the weight ratio, 55 parts of resin, 3 parts of polyester low-temperature accelerator with fumed silica as a carrier, 7 parts of β-hydroxyalkylamide, 0.5 parts of VOK-DS330 dispersant, 3 parts of benzoin, 20 parts of barium sulfate, 4 parts of acrylic ester leveling agent, 3 parts of acrylic ester copolymer and 7 parts of calcium carbonate are fully mixed, and then mixed and extruded through a twin-screw extruder, and the front zone temperature of the twin-screw extruder is set to 120°C, the rear zone temperature is set to 105°C, and the speed of the twin screw is set to 35r / min. Then, the mixture is subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coat powder coating.

[0050] Example 2:

[0051] A method for preparing a low-temperature curing thin-coat powder coating comprises the following steps:

[0052] Neopentyl glycol, ethylene glycol, and 1,4-cyclohexanedimethanol were mixed in a mass ratio of 3:2:4, water was added, and the mixture was heated to 80° C. at 30 r / min to obtain a mixture;

[0053] Continuing to add terephthalic acid, adipic acid, and isophthalic acid in a mass ratio of 7:3:4 to the mixture, and adding 0.8% of monobutyltin oxide based on the mass percentage of the resin, adjusting the temperature to 120 r / min, continuing to heat to 210° C., maintaining for 25 minutes, and then adding 4% of an antioxidant based on the mass percentage of the resin, wherein the antioxidant is a mixture of pentaerythritol dioctadecyl phosphite and trimellitic anhydride in a mass ratio of 3:4, continuing to stir for 20 minutes, cooling to 200° C., continuing to reflux for 45 minutes, connecting condensed water, and obtaining a resin after the reaction is completed;

[0054] According to the weight ratio, 53 parts of resin, 2 parts of polyester low-temperature accelerator with fumed silica as a carrier, 8 parts of β-hydroxyalkylamide, 0.6 parts of VOK-DS330 dispersant, 4 parts of benzoin, 17 parts of barium sulfate, 5 parts of acrylic ester leveling agent, 4 parts of acrylic ester copolymer and 8 parts of calcium carbonate are fully mixed, and then mixed and extruded through a twin-screw extruder, and the front zone temperature of the twin-screw extruder is set to 120°C, the rear zone temperature is set to 105°C, and the speed of the twin screw is set to 30r / min. Then, the mixture is subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coat powder coating.

[0055] Example 3:

[0056] A method for preparing a low-temperature curing thin-coat powder coating comprises the following steps:

[0057] Neopentyl glycol, ethylene glycol, and 1,4-cyclohexanedimethanol were mixed in a mass ratio of 2:3:5, water was added, and the mixture was heated to 85° C. at 35 rpm to obtain a mixture;

[0058] Continuing to add terephthalic acid, adipic acid, and isophthalic acid in a mass ratio of 5:2:4 to the mixture, and adding 1% of monobutyltin oxide based on the mass percentage of the resin, adjusting the temperature to 150 r / min, continuing to raise the temperature to 220° C., maintaining for 30 minutes, and then adding 5% of an antioxidant based on the mass percentage of the resin, wherein the antioxidant is a mixture of pentaerythritol dioctadecyl phosphite and trimellitic anhydride in a mass ratio of 3:4, continuing to stir for 18 minutes, cooling to 185° C., continuing to reflux for 50 minutes, connecting condensed water, and obtaining a resin after the reaction is completed;

[0059] According to the weight ratio, 54 parts of resin, 3 parts of polyester low-temperature accelerator with fumed silica as a carrier, 9 parts of β-hydroxyalkylamide, 0.7 parts of VOK-DS330 dispersant, 6 parts of benzoin, 18 parts of barium sulfate, 4 parts of acrylic ester leveling agent, 6 parts of acrylic ester copolymer and 7 parts of calcium carbonate are fully mixed, and then mixed and extruded through a twin-screw extruder, and the front zone temperature of the twin-screw extruder is set to 118°C, the rear zone temperature is set to 102°C, and the speed of the twin screw is set to 35r / min. Then, the mixture is subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coat powder coating.

[0060] Example 4:

[0061] A method for preparing a low-temperature curing thin-coat powder coating comprises the following steps:

[0062] Neopentyl glycol, ethylene glycol, and 1,4-cyclohexanedimethanol in a mass ratio of 2:3:5 were mixed, water was added, and the mixture was heated to 82° C. at 40 r / min to obtain a mixture;

[0063] Continuing to add terephthalic acid, adipic acid, and isophthalic acid in a mass ratio of 6:2:5 to the mixture, and adding 0.7% of monobutyltin oxide based on the mass percentage of the resin, adjusting the temperature to 150 r / min, continuing to heat to 220° C., maintaining for 20 minutes, and then adding 5% of an antioxidant based on the mass percentage of the resin, wherein the antioxidant is a mixture of pentaerythritol dioctadecyl phosphite and trimellitic anhydride in a mass ratio of 2:5, continuing to stir for 20 minutes, cooling to 200° C., continuing to reflux for 55 minutes, connecting condensed water, and obtaining a resin after the reaction is completed;

[0064] According to the weight ratio, 55 parts of resin, 3 parts of polyester low-temperature accelerator with fumed silica as a carrier, 7 parts of β-hydroxyalkylamide, 0.5 parts of VOK-DS330 dispersant, 5 parts of benzoin, 18 parts of barium sulfate, 3 parts of acrylic ester leveling agent, 6 parts of acrylic ester copolymer and 7 parts of calcium carbonate are fully mixed, and then mixed and extruded through a twin-screw extruder, and the front zone temperature of the twin-screw extruder is set to 115°C, the rear zone temperature is set to 105°C, and the speed of the twin screw is set to 30r / min. Then, the mixture is subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coat powder coating.

[0065] It should be noted that the particle size distribution of the low temperature curing thin coating powder coatings of Examples 1 to 4 meets the following conditions: 50 <25μm, D 10 >11μm, D 90 <40μm.

[0066] Comparative Examples 1 to 5:

[0067] The difference between Comparative Examples 1 to 5 and Example 4 is that the raw materials and the ratios of the raw materials used to prepare the resins in Comparative Examples 1 to 5 are different, as shown in Table 1. The other differences are the same as Example 4.

[0068] Comparative Example 6:

[0069] The difference between Comparative Example 6 and Example 4 is that no antioxidant is added to the resin in Comparative Example 6, and the rest is the same as Example 4.

[0070] Comparative Example 7:

[0071] The difference between Comparative Example 7 and Example 4 is that in Comparative Example 7, no fumed silica is added as a carrier of the polyester low-temperature accelerator, and the rest is the same as in Example 4.

[0072] Comparative Example 8:

[0073] The difference between Comparative Example 8 and Example 4 is that a commercially available accelerator is used in Comparative Example 8, and the rest is the same as Example 4.

[0074] Table 1:

[0075] The powder coatings prepared in Examples 1 to 4 and the powder coatings prepared in Comparative Examples 1 to 8 were tested for appearance, storage stability, impact resistance, and corrosion resistance. The thickness of the coating was 40 μm. The appearance was observed visually to check for smoothness, uniform color, bubbles, cracks, shrinkage holes, and orange peel patterns. Storage stability refers to changes in the powder coating after sealed storage for three months at 25° C. in a ventilated and dry environment. Impact resistance was measured in accordance with GB1732-79 (50 kg.cm). Weather resistance was measured (QUVB accelerated aging test for 4000 h). The appearance and storage stability results are shown in Table 2 below. Leveling, impact resistance, and weather resistance are shown in Table 3.

[0076] Table 2:

[0077] From the data analysis in Table 2, it can be seen that the present application obtains a storage-stable powder coating by optimizing the raw materials and the ratio of the raw materials for the preparation of the resin, and the coating surface is overall flat and smooth, without bubbles, shrinkage cavities, pinholes, or orange peel patterns, and a high-quality coating can be obtained.

[0078] Table 3:

[0079] From the data analysis of Table 3, it can be seen that the present application can obtain a powder coating with excellent leveling performance, impact resistance and weather resistance by optimizing the raw materials and raw material ratios of the resin. The difference between Comparative Examples 1 to 5 and Example 4 is that the raw materials and raw material ratios of the resin are different, resulting in different performance of the powder coatings, and worse than that of Example 4, indicating that the raw materials and raw material ratios of the resin of the present application have a significant effect on the technical effect of the present application. The difference between Comparative Example 6 and Example 4 is that no antioxidant is added in Comparative Example 6. Adding an antioxidant in the resin preparation stage helps to improve the weather resistance of the subsequent powder coating. Comparative Example 7 does not add a polyester low-temperature accelerator with fumed silica as a carrier, and Comparative Example 8 adds a commercially available accelerator, but the effects are worse than those of Example 4, indicating that the present application uses a nano-scale low-temperature accelerator with fumed silica as a carrier to improve the dispersibility of the reaction accelerator in the raw materials and reduce the problems of gloss reduction and coating performance deterioration caused by the current uneven dispersion of the reaction accelerator.

[0080] In addition, the following tests were conducted on the particle size distribution of the powder coating. The specific particle size distribution and results are shown in Table 4.

[0081] Table 4:

[0082] From the data analysis of Table 4, it can be seen that this application reduces D 50 The particle size distribution is narrowed to enable thin coating, avoiding poor powder flowability and coating grit. The thin coating process is combined with the low-temperature curing process to further assist the low-temperature curing of the coating by thin coating / reducing the film thickness.

[0083] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A low temperature curing thin coating powder coating, characterized in that: According to the weight ratio, it includes the following raw materials: 45 to 55 parts of resin, 1 to 3 parts of accelerator, 3 to 9 parts of curing agent, 0.5 to 1 part of dispersant, 3 to 7 parts of benzoin, 15 to 20 parts of barium sulfate, 1 to 5 parts of leveling agent, 1 to 7 parts of brightener, and 7 to 9 parts of pigment; The raw materials for preparing the resin include neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid, isophthalic acid, a catalyst and an antioxidant. In terms of mass ratio, the ratio of the neopentyl glycol, ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, adipic acid and isophthalic acid is (1-3): (1-4): (1-5): (3-7): (1-3): (2-5), the added amount of the catalyst accounts for 0.05% to 1% of the mass percentage of the resin, and the antioxidant accounts for 0.1% to 7% of the mass percentage of the resin. The promoter is a nano-scale low-temperature promoter with fumed silica as a carrier.

2. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The catalyst is monobutyltin oxide.

3. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The antioxidant is obtained by mixing pentaerythritol dioctadecyl diphosphite and trimellitic anhydride in a mass ratio of (1-3): (2-5).

4. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The preparation method of the resin is: Neopentyl glycol, ethylene glycol and 1,4-cyclohexanedimethanol were mixed, water was added, and the mixture was heated to 75° C. to 85° C. at 25 rpm to 50 rpm to obtain a mixture; Continue to add terephthalic acid, adipic acid, isophthalic acid and catalyst to the mixture, adjust to 100r / min~200r / min, continue to heat to 200℃~220℃, maintain for 20min~30min, then add antioxidant, continue stirring for 10min~20min, cool to 180℃~200℃, continue to reflux for 40min~60min, connect condensed water, and obtain resin after the reaction is completed.

5. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The acid value of the resin is 25 mg / KOH / g to 70 mg / KOH / g.

6. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The nano-scale low-temperature accelerator is a mixture of a polyester low-temperature accelerator and an ultra-low-temperature epoxy curing accelerator, or a polyester low-temperature curing accelerator.

7. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The curing agent is β-hydroxyalkylamide.

8. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The dispersant is a mixture of one or more of VOK-DS330 dispersant, VOK-DS360 dispersant, VOK-DS361 dispersant, VOK-DS363 dispersant, VOK-DS6203 dispersant, and VOK-DS6904 dispersant.

9. The low temperature curing thin coating powder coating according to claim 1, characterized in that: The leveling agent is an acrylate leveling agent.

10. A method for preparing a low-temperature curing thin-coat powder coating, characterized in that: The preparation method is used to prepare the low-temperature curing thin-coat powder coating according to any one of claims 1 to 9, and the preparation method comprises the following steps: The resin, accelerator, curing agent, dispersant, benzoin, barium sulfate, leveling agent, brightener and pigment are fully mixed and extruded through a twin-screw extruder, and then subjected to tableting and crushing treatment, micro-crushing treatment and sieving treatment to obtain a low-temperature curing thin-coating powder coating.