Anti-static powder coating and preparation process thereof

Abstract

The invention belongs to the technical field of powder coatings, and particularly provides an anti-static powder coating and a preparation process thereof. The anti-static powder coating comprises the following components: modified epoxy resin, a curing agent, a composite conductive filler, a flatting agent, a defoaming agent and a pigment filler, the modified epoxy resin is prepared from indole modified epoxy resin; the composite conductive filler is prepared from a carbon nanotube and a hyperbranched functional polymer; the hyperbranched functional polymer is prepared from hydroxyl-terminated hyperbranched polyester, pyrene butyric acid, amino-terminated polyethylene glycol and carboxyl triazoline diketone. The anti-static powder coating prepared by the invention has good anti-static performance, adhesive force and self-repairing performance.

Description

Technical Field

[0001] This application belongs to the field of powder coating technology, and in particular relates to an antistatic powder coating and its preparation process. Background Technology

[0002] Powder coatings, as a surface treatment material free of volatile organic compounds (VOCs), are gradually replacing traditional solvent-based coatings due to their excellent environmental performance and construction efficiency, and are widely used in construction, flooring, furniture, and electronics. In recent years, the demand for functional powder coatings has become increasingly prominent, with antistatic properties emerging as a key requirement. Antistatic powder coatings are made by adding conductive fillers to the coating. The contact between these fillers creates "conductive channels," forming a continuous conductive network. Conductive fillers typically include conductive carbon fibers, metal fillers, graphite powder, and conductive mica. Sufficient filler content is required to form conductive chains, but excessive filler content can lead to uneven dispersion. Furthermore, during long-term use, factors such as temperature changes, mechanical vibration, chemical media, and humid environments can cause micro-cracks or peeling at the filler-resin interface, leading to separation, network breakage, and significantly reduced conductivity.

[0003] To address the issue of weakened antistatic performance of antistatic coatings over long-term use, techniques such as surface modification of fillers and incorporation of conductive resins are often employed. For example, patent application CN108977000A discloses an antistatic powder coating. This antistatic powder coating uses polyamide resin and silane coupling agent to modify carbon black, effectively improving the compatibility between carbon black and the resin matrix, resulting in an antistatic protective layer with good adhesion and no peeling.

[0004] The aforementioned document describes how adding polyester resin and modifying the surface of carbon black material can effectively improve the impact resistance of the antistatic protective layer and provide effective antistatic protection. However, it does not address the issue of reduced conductivity caused by cracks or separation at the filler-resin interface under long-term use. Summary of the Invention

[0005] To address the aforementioned issues and further improve the long-term antistatic properties of antistatic powder, this application provides an antistatic powder coating and its preparation process.

[0006] This application first provides an antistatic powder coating, comprising the following components by weight: 35-60 parts modified epoxy resin, 2-3 parts curing agent, 5-20 parts composite conductive filler, 0.7-1.5 parts leveling agent, 0.3-1 part defoamer, and 10-30 parts pigments and fillers. The modified epoxy resin is prepared from indole-modified epoxy resin; The composite conductive filler is made of carbon nanotubes and hyperbranched functional polymers. The hyperbranched functional polymer is prepared from hydroxyl-terminated hyperbranched polyester, pyrene butyric acid, amino-terminated polyethylene glycol, and carboxylated triazoline dione.

[0007] Furthermore, the preparation method of the modified epoxy resin includes the following steps: reacting epoxy resin, 5-methoxytryptamine and N,N-dimethyl-1,6-hexanediamine to obtain the modified epoxy resin.

[0008] Furthermore, the preparation method of the composite conductive filler includes the following steps: carbon nanotubes and hyperbranched functional polymers are ultrasonically dispersed and composited in a solvent, and then separated and dried to obtain the filler.

[0009] Furthermore, the mass ratio of the carbon nanotubes to the hyperbranched functional polymer is 1:3-5.

[0010] Furthermore, the preparation method of the hyperbranched functional polymer includes the following steps: A1, amide condensation reaction of amino-terminated polyethylene glycol with pyrene butyric acid to obtain pyrene butyric acid-polyethylene glycol; A2, amide condensation reaction of pyrene butyric acid-polyethylene glycol with carboxylated triazolinone to obtain pyrene butyric acid-polyethylene glycol-triazolinone; A3, esterification reaction of hydroxyl-terminated hyperbranched polyester with pyrene butyric acid-polyethylene glycol-triazolinone to obtain the hyperbranched functional polymer.

[0011] Furthermore, the preparation method of terminal amino polyethylene glycol includes the following steps: B1, polyethylene glycol reacts with TsCl to obtain polyethylene glycol p-toluenesulfonate; B2, polyethylene glycol p-toluenesulfonate reacts with concentrated nitric acid under reflux to obtain terminal amino polyethylene glycol.

[0012] Furthermore, the preparation method of carboxytriazolinidone includes the following steps: C1, diphenyl carbonate and ethyl carbamate are reacted by heating and stirring to obtain dicarboxylic acid ethylphenylhydrazine; C2, L-glutamic acid-5-tert-butyl ester and dicarboxylic acid ethylphenylhydrazine are reacted by triethylamine catalysis to obtain aminourea; C3, aminourea is cyclized by K2CO3, MgSO4 and N2O4 to obtain tert-butyl ester protected carboxytriazolinidone; C4, tert-butyl ester protected carboxytriazolinidone is deprotected by trifluoroacetic acid, dichloromethane and triethylsilane to obtain carboxytriazolinidone.

[0013] Furthermore, the preparation method of hydroxyl-terminated hyperbranched polyester includes the following steps: trimethylolpropane and 2,2-dimethylolpropionic acid are reacted by DCC catalysis to obtain hydroxyl-terminated hyperbranched polyester.

[0014] Furthermore, this application provides a method for preparing an antistatic powder coating, comprising the following steps: S1, firstly, dry-mixing the composite conductive filler with pigments and fillers, and then adding the remaining components together into a high-speed mixer for premixing; S2, after mixing, feeding the mixture into a twin-screw extruder to form a uniform melt; S3, feeding the molten coating into a sheet-making machine to form sheets, and then feeding the formed sheet material into a grinding hopper for grinding and pulverizing, and grading and sieving to obtain the antistatic powder coating.

[0015] Furthermore, in S2, the temperature of each section of the twin-screw extruder is controlled at 100-110℃, with the feeding section temperature set at 100-105℃, and the middle section and die head section gradually increasing to 105-110℃.

[0016] Compared with the prior art, this application has the following beneficial effects: 1. The composite conductive filler is composed of hyperbranched polyester, pyrene-butyric acid-polyethylene glycol-triazolidinedione, and carbon nanotubes. Pyrene-butyric acid and carbon nanotubes are bonded through π-π interactions. At the same time, the branched structure and excess hydroxyl groups on the surface of the hyperbranched polyester can effectively disperse the carbon nanotubes. The indole-modified epoxy resin can quickly undergo a click chemical reaction with the triazolidinedione in the composite conductive filler, so that the carbon nanotubes can be uniformly dispersed in the resin matrix, preventing them from migrating or falling off during coating curing and long-term use, thereby forming a stable and efficient conductive network.

[0017] 2. When the coating is subjected to mechanical forces such as vibration, impact, and friction, the CN bond connecting the indole group of the modified epoxy resin and the triazolinone of the composite conductive filler exhibits rapid and reversible stress response, which can be broken and recombined at room temperature. At the same time, since the triazolinone and pyrene butyric acid are connected through polyethylene glycol, the polymer chain rearrangement during the repair process drives the pyrene butyric acid to anchor the exposed CNTs, thereby maintaining the integrity of the conductive network of the polymer and filler and improving the long-term antistatic performance of the coating.

[0018] 3. The branched structure of hyperbranched polyester effectively hinders crack propagation, disperses stress, and improves the impact resistance and toughness of powder conductive coatings. The numerous hydroxyl and carboxyl termini on its surface also greatly enhance the chemical bonding and hydrogen bonding with the epoxy resin matrix, improving the overall density of the crosslinked network. Attached Figure Description

[0019] Figure 1 SEM images of the repair of bending fractures in antistatic powder coatings, with the left side showing Comparative Example 2 and the right side showing Example 2. Detailed Implementation

[0020] To make the inventive objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. Obviously, the described embodiments are only a portion of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only” is used, in which case another component may be added.

[0023] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0024] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0025] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0026] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0027] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0028] Example 1 The antistatic powder coating in this embodiment comprises the following components by weight: 500g modified epoxy resin, 25g curing agent, 100g composite conductive filler, 8g leveling agent, 3g defoamer, and 250g pigments and fillers.

[0029] The method for preparing the antistatic powder coating in this embodiment is as follows: S1. First, dry mix the composite conductive filler and pigment filler at 1500 r / min for 2 min. Then, put the remaining components into a high-speed mixer and premix at 2000 r / min for 4 min.

[0030] S2, after mixing, is fed into a twin-screw extruder with a screw length-to-diameter ratio of 40:1. The temperature of the feeding section is set to 100℃, and the temperature of the middle section and the die head section is gradually increased to 105℃ to form a uniform melt.

[0031] S3. The molten coating is fed into the sheet-making machine to form sheets. The resulting sheet material is then fed into the grinding hopper for grinding and pulverizing. The sheets are then graded and sieved. The powder particle size range is set to 20-50μm to obtain an antistatic powder coating.

[0032] The modified epoxy resin in this embodiment is prepared as follows: 50g of epoxy resin (E12, epoxy equivalent 750g / eq), 1.69g of 5-methoxytryptamine and 0.52g of N,N-dimethyl-1,6-hexanediamine were dissolved in 200mL of DMF and placed in a three-necked flask. The reaction was carried out at 85℃ for 24h to obtain indole-modified epoxy resin.

[0033] The preparation method of the composite conductive filler in this embodiment is as follows: 3g of hyperbranched functional polymer was dissolved in 50mL of DMF, ultrasonically dispersed for 30min, 1g of carbon nanotubes was added, ultrasonicated for 1h at room temperature, stirred for 10h, filtered, washed twice with DMF, and then vacuum dried to obtain the composite conductive filler.

[0034] The preparation method of the hyperbranched functional polymer in this embodiment is as follows: A1. Dissolve 1g of amino-terminated polyethylene glycol in 30mL of dichloromethane, add 0.144g of pyrene-butyric acid, 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT, stir and react for 5h under nitrogen protection, then wash and dry to obtain pyrene-butyric acid-polyethylene glycol.

[0035] A2, 0.165g of carboxytriazolinidone and the previous product pyrene-butyric acid-polyethylene glycol were dissolved in 30mL of dichloromethane, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred and reacted for 5h. After washing and drying, pyrene-butyric acid-polyethylene glycol-triazolinidone was obtained.

[0036] A3, 0.65g of hydroxyl-terminated hyperbranched polyester and the previous product pyrene-butyric acid-polyethylene glycol-triazolinidone were dissolved in 30ml of LDMF, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred at room temperature for 24h, purified and dried to obtain the hyperbranched functional polymer.

[0037] The preparation method of the amino-terminated polyethylene glycol in this embodiment is as follows: B1. Take 4g of polyethylene glycol (molecular weight 2000) and 1.144g of TsCl and dissolve them in 20mL of CH2Cl2 and 10mL of pyridine, respectively. Add the TsCl solution to the PEG solution while stirring, react at 25℃ for 24h, extract three times with 15mL of HCl (3mol / L), collect the lower oily liquid, centrifuge at 10000rpm for 5min, collect the upper transparent oily liquid, freeze dry for 24h, add an appropriate amount of THF, sonicate to dissolve, then add diethyl ether (about twice the amount of THF), refrigerate for 20min, filter, and vacuum dry at 35℃ overnight to obtain polyethylene glycol p-toluenesulfonate.

[0038] B2, add 23 mL concentrated nitric acid and 1 mmol polyethylene glycol p-toluenesulfonate to a 50 mL round-bottom flask, sonicate to dissolve, heat to reflux and then cool to room temperature, extract three times with 15 mL CH2Cl2, combine the extracted oily liquids, add 40 mL NaOH (1 mol / L) solution, stir at 25 °C for 2 h, separate the oily liquid, wash with 40 mL saturated NaCl until neutral, rotary evaporate, and then vacuum dry at 35 °C to obtain amino-terminated polyethylene glycol.

[0039] The preparation method of the carboxy-triazolidinedione in this embodiment is as follows: C1, 60.02 g of diphenyl carbonate and 58.37 g of ethyl carbamate were weighed and dissolved in 500 mL of diethyl ether. The mixture was heated and stirred at 90 °C for 1 h. The reaction was then precipitated in water (1.5 L) to form an emulsion. The precipitate was stirred rapidly to form a white solid. The precipitate was filtered and dried under vacuum at 40 °C for 12 h to obtain dicarboxylic acid ethylphenylhydrazine.

[0040] C2, 9.1 g L-glutamic acid-5-tert-butyl ester and 10 g dicarboxylic acid ethylphenylhydrazine were dissolved in 150 mL of acetonitrile:water solution (volume ratio 9:1), 12.4 mL of triethylamine was added, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, the acetonitrile was removed under vacuum, the remaining aqueous phase was diluted with 400 mL of water, and extracted three times with ethyl acetate. The aqueous phase was acidified with hydrochloric acid (36%) to pH 1, filtered, and dried under vacuum at 40 °C overnight to obtain aminourea.

[0041] C3, 6.05 g of aminourea was dissolved in 100 mL of ethanol, 12.7 g of K2CO3 was added, and the mixture was refluxed and stirred for 12 h. The reaction was then cooled to room temperature, filtered, and dried. The resulting solid was dissolved in a minimum volume of 1,4-dioxane, acidified with HCl to pH 1 at room temperature, filtered, and dried under vacuum. 0.92 g of the solid was suspended in 100 mL of anhydrous ethyl acetate, and 5.15 g of MgSO4 was added. The reaction mixture was rinsed with N2O4 gas for about 5 min, filtered, and dried under vacuum to obtain tert-butyl protected triazolinone.

[0042] C4, under moisture-free conditions, 1 mmol of tert-butyl ester was used to protect triazolinone, and 13 mmol of trifluoroacetic acid and 32 mmol of dichloromethane were added for acid hydrolysis. 2.5 mmol of triethylsilane was added, and the mixture was stirred at room temperature until the reaction was complete. After the solvent was evaporated, the mixture was washed with diethyl ether and dried under vacuum to obtain carboxytriazolinone, which was stored under an inert atmosphere at -20°C.

[0043] The preparation method of the hydroxyl-terminated hyperbranched polyester in this embodiment is as follows: Weigh 0.67 g of trimethylolpropane and 6.04 g of 2,2-dimethylolpropionic acid into a 250 mL round-bottom flask, add 5 mL of DMF, and sonicate until completely dissolved. Under ice bath and magnetic stirring, inject DCC solution (1.856 g of DCC dissolved in 5 mL of DMF) into the flask at a rate of 1 mL / h using a micro-injection pump. After injection, stir the reaction mixture under ice bath for 4 h. Centrifuge the reaction mixture, add 1 mL of deionized water to the supernatant, and repeat 3-5 times. Then place the supernatant in a 4 °C refrigerator and let it stand overnight. Centrifuge and repeat the operation until no precipitate dissolves. Remove the solvent from the supernatant by rotary evaporation and dry under vacuum at 80 °C to obtain the terminal hydroxyl hyperbranched polyester.

[0044] Example 2 The antistatic powder coating in this embodiment comprises the following components by weight: 600g modified epoxy resin, 30g curing agent, 160g composite conductive filler, 10g leveling agent, 5g defoamer, and 300g pigments and fillers.

[0045] The method for preparing the antistatic powder coating in this embodiment is as follows: S1. First, dry mix the composite conductive filler and pigment filler at 1500 r / min for 2 min. Then, put the remaining components into a high-speed mixer and premix at 2000 r / min for 4 min.

[0046] S2, after mixing, is fed into a twin-screw extruder with a screw length-to-diameter ratio of 40:1. The temperature of the feeding section is set to 100℃, and the temperature of the middle section and the die head section is gradually increased to 105℃ to form a uniform melt.

[0047] S3. The molten coating is fed into the sheet-making machine to form sheets. The resulting sheet material is then fed into the grinding hopper for grinding and pulverizing. The sheets are then graded and sieved. The powder particle size range is set to 20-50μm to obtain an antistatic powder coating.

[0048] The preparation method of the modified epoxy resin in this embodiment is the same as that in Example 1.

[0049] The preparation method of the composite conductive filler in this embodiment is as follows: 4g of hyperbranched functional polymer was dissolved in 50mL of DMF, ultrasonically dispersed for 30min, 1g of carbon nanotubes was added, ultrasonicated for 1h at room temperature, stirred for 10h, filtered, washed twice with DMF, and then vacuum dried to obtain the composite conductive filler.

[0050] The preparation method of the hyperbranched functional polymer in this embodiment is as follows: A1. Dissolve 1g of amino-terminated polyethylene glycol in 30mL of dichloromethane, add 0.144g of pyrene-butyric acid, 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT, stir and react for 5h under nitrogen protection, then wash and dry to obtain pyrene-butyric acid-polyethylene glycol.

[0051] A2, 0.165g of carboxytriazolinidone and the previous product pyrene-butyric acid-polyethylene glycol were dissolved in 30mL of dichloromethane, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred and reacted for 5h. After washing and drying, pyrene-butyric acid-polyethylene glycol-triazolinidone was obtained.

[0052] A3, 0.65g of hydroxyl-terminated hyperbranched polyester and the previous product pyrene-butyric acid-polyethylene glycol-triazolinidone were dissolved in 30ml of LDMF, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred at room temperature for 24h, purified and dried to obtain the hyperbranched functional polymer.

[0053] The preparation method of the amino-terminated polyethylene glycol in this embodiment is as follows: B1. Take 4g of polyethylene glycol (molecular weight 2000) and 1.144g of TsCl and dissolve them in 20mL of CH2Cl2 and 10mL of pyridine, respectively. Add the TsCl solution to the PEG solution while stirring, react at 25℃ for 24h, extract three times with 15mL of HCl (3mol / L), collect the lower oily liquid, centrifuge at 10000rpm for 5min, collect the upper transparent oily liquid, freeze dry for 24h, add an appropriate amount of THF, sonicate to dissolve, then add diethyl ether (about twice the amount of THF), refrigerate for 20min, filter, and vacuum dry at 35℃ overnight to obtain polyethylene glycol p-toluenesulfonate.

[0054] B2, add 23 mL concentrated nitric acid and 1 mmol polyethylene glycol p-toluenesulfonate to a 50 mL round-bottom flask, sonicate to dissolve, heat to reflux and then cool to room temperature, extract three times with 15 mL CH2Cl2, combine the extracted oily liquids, add 40 mL NaOH (1 mol / L) solution, stir at 25 °C for 2 h, separate the oily liquid, wash with 40 mL saturated NaCl until neutral, rotary evaporate, and then vacuum dry at 35 °C to obtain amino-terminated polyethylene glycol.

[0055] The preparation method of the carboxy-triazolidinedione in this embodiment is as follows: C1, 60.02 g of diphenyl carbonate and 58.37 g of ethyl carbamate were weighed and dissolved in 500 mL of diethyl ether. The mixture was heated and stirred at 90 °C for 1 h. The reaction was then precipitated in water (1.5 L) to form an emulsion. The precipitate was stirred rapidly to form a white solid. The precipitate was filtered and dried under vacuum at 40 °C for 12 h to obtain dicarboxylic acid ethylphenylhydrazine.

[0056] C2, 9.1 g L-glutamic acid-5-tert-butyl ester and 10 g dicarboxylic acid ethylphenylhydrazine were dissolved in 150 mL of acetonitrile:water solution (volume ratio 9:1), 12.4 mL of triethylamine was added, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, the acetonitrile was removed under vacuum, the remaining aqueous phase was diluted with 400 mL of water, and extracted three times with ethyl acetate. The aqueous phase was acidified with hydrochloric acid (36%) to pH 1, filtered, and dried under vacuum at 40 °C overnight to obtain aminourea.

[0057] C3, 6.05 g of aminourea was dissolved in 100 mL of ethanol, 12.7 g of K2CO3 was added, and the mixture was refluxed and stirred for 12 h. The reaction was then cooled to room temperature, filtered, and dried. The resulting solid was dissolved in a minimum volume of 1,4-dioxane, acidified with HCl to pH 1 at room temperature, filtered, and dried under vacuum. 0.92 g of the solid was suspended in 100 mL of anhydrous ethyl acetate, and 5.15 g of MgSO4 was added. The reaction mixture was rinsed with N2O4 gas for about 5 min, filtered, and dried under vacuum to obtain tert-butyl protected triazolinone.

[0058] C4, under moisture-free conditions, 1 mmol of tert-butyl ester was used to protect triazolinone, and 13 mmol of trifluoroacetic acid and 32 mmol of dichloromethane were added for acid hydrolysis. 2.5 mmol of triethylsilane was added, and the mixture was stirred at room temperature until the reaction was complete. After the solvent was evaporated, the mixture was washed with diethyl ether and dried under vacuum to obtain carboxytriazolinone, which was stored under an inert atmosphere at -20°C.

[0059] The preparation method of the hydroxyl-terminated hyperbranched polyester in this embodiment is as follows: Weigh 0.67 g of trimethylolpropane and 6.04 g of 2,2-dimethylolpropionic acid into a 250 mL round-bottom flask, add 5 mL of DMF, and sonicate until completely dissolved. Under ice bath and magnetic stirring, inject DCC solution (1.856 g of DCC dissolved in 5 mL of DMF) into the flask at a rate of 1 mL / h using a micro-injection pump. After injection, stir the reaction mixture under ice bath for 4 h. Centrifuge the reaction mixture, add 1 mL of deionized water to the supernatant, and repeat 3-5 times. Then place the supernatant in a 4 °C refrigerator and let it stand overnight. Centrifuge and repeat the operation until no precipitate dissolves. Remove the solvent from the supernatant by rotary evaporation and dry under vacuum at 80 °C to obtain the terminal hydroxyl hyperbranched polyester.

[0060] Example 3 The antistatic powder coating in this embodiment comprises the following components by weight: 400g modified epoxy resin, 20g curing agent, 156g composite conductive filler, 7g leveling agent, 4g defoamer, and 250g pigments and fillers.

[0061] The method for preparing the antistatic powder coating in this embodiment is as follows: S1. First, dry mix the composite conductive filler and pigment filler at a speed of 1500 r / min for 2 min. Then, put the remaining components into a high-speed mixer and premix at 2000 r / min for 4 min.

[0062] S2, after mixing, is fed into a twin-screw extruder with a screw length-to-diameter ratio of 40:1. The temperature of the feeding section is set at 105℃, and gradually increased to 110℃ in the middle and die sections to form a uniform melt.

[0063] S3. The molten coating is fed into the sheet-making machine to form sheets. The resulting sheet material is then fed into the grinding hopper for grinding and pulverizing. The sheets are then graded and sieved. The powder particle size range is set to 20-50μm to obtain an antistatic powder coating.

[0064] The preparation method of the modified epoxy resin in this embodiment is the same as that in Example 1.

[0065] The preparation method of the composite conductive filler in this embodiment is as follows: 5g of hyperbranched functional polymer was dissolved in 50mL of DMF, ultrasonically dispersed for 30min, 1g of carbon nanotubes was added, ultrasonicated for 1h at room temperature, stirred for 10h, filtered, washed twice with DMF, and then vacuum dried to obtain the composite conductive filler.

[0066] The preparation method of the hyperbranched functional polymer in this embodiment is as follows: A1. Dissolve 1g of amino-terminated polyethylene glycol in 30mL of dichloromethane, add 0.144g of pyrene-butyric acid, 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT, stir and react for 5h under nitrogen protection, then wash and dry to obtain pyrene-butyric acid-polyethylene glycol.

[0067] A2, 0.165g of carboxytriazolinidone and the previous product pyrene-butyric acid-polyethylene glycol were dissolved in 30mL of dichloromethane, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred and reacted for 5h. After washing and drying, pyrene-butyric acid-polyethylene glycol-triazolinidone was obtained.

[0068] A3, 0.65g of hydroxyl-terminated hyperbranched polyester and the previous product pyrene-butyric acid-polyethylene glycol-triazolinidone were dissolved in 30ml of LDMF, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred at room temperature for 24h, purified and dried to obtain the hyperbranched functional polymer.

[0069] The preparation method of the amino-terminated polyethylene glycol in this embodiment is as follows: B1. Take 4g of polyethylene glycol (molecular weight 2000) and 1.144g of TsCl and dissolve them in 20mL of CH2Cl2 and 10mL of pyridine, respectively. Add the TsCl solution to the PEG solution while stirring, react at 25℃ for 24h, extract three times with 15mL of HCl (3mol / L), collect the lower oily liquid, centrifuge at 10000rpm for 5min, collect the upper transparent oily liquid, freeze dry for 24h, add an appropriate amount of THF, sonicate to dissolve, then add diethyl ether (about twice the amount of THF), refrigerate for 20min, filter, and vacuum dry at 35℃ overnight to obtain polyethylene glycol p-toluenesulfonate.

[0070] B2, add 23 mL concentrated nitric acid and 1 mmol polyethylene glycol p-toluenesulfonate to a 50 mL round-bottom flask, sonicate to dissolve, heat to reflux and then cool to room temperature, extract three times with 15 mL CH2Cl2, combine the extracted oily liquids, add 40 mL NaOH (1 mol / L) solution, stir at 25 °C for 2 h, separate the oily liquid, wash with 40 mL saturated NaCl until neutral, rotary evaporate, and then vacuum dry at 35 °C to obtain amino-terminated polyethylene glycol.

[0071] The preparation method of the carboxy-triazolidinedione in this embodiment is as follows: C1, 60.02 g of diphenyl carbonate and 58.37 g of ethyl carbamate were weighed and dissolved in 500 mL of diethyl ether. The mixture was heated and stirred at 90 °C for 1 h. The reaction was then precipitated in water (1.5 L) to form an emulsion. The precipitate was stirred rapidly to form a white solid. The precipitate was filtered and dried under vacuum at 40 °C for 12 h to obtain dicarboxylic acid ethylphenylhydrazine.

[0072] C2, 9.1 g L-glutamic acid-5-tert-butyl ester and 10 g dicarboxylic acid ethylphenylhydrazine were dissolved in 150 mL of acetonitrile:water solution (volume ratio 9:1), 12.4 mL of triethylamine was added, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, the acetonitrile was removed under vacuum, the remaining aqueous phase was diluted with 400 mL of water, and extracted three times with ethyl acetate. The aqueous phase was acidified with hydrochloric acid (36%) to pH 1, filtered, and dried under vacuum at 40 °C overnight to obtain aminourea.

[0073] C3, 6.05 g of aminourea was dissolved in 100 mL of ethanol, 12.7 g of K2CO3 was added, and the mixture was refluxed and stirred for 12 h. The reaction was then cooled to room temperature, filtered, and dried. The resulting solid was dissolved in a minimum volume of 1,4-dioxane, acidified with HCl to pH 1 at room temperature, filtered, and dried under vacuum. 0.92 g of the solid was suspended in 100 mL of anhydrous ethyl acetate, and 5.15 g of MgSO4 was added. The reaction mixture was rinsed with N2O4 gas for about 5 min, filtered, and dried under vacuum to obtain tert-butyl protected triazolinone.

[0074] C4, under moisture-free conditions, 1 mmol of tert-butyl ester was used to protect triazolinone, and 13 mmol of trifluoroacetic acid and 32 mmol of dichloromethane were added for acid hydrolysis. 2.5 mmol of triethylsilane was added, and the mixture was stirred at room temperature until the reaction was complete. After the solvent was evaporated, the mixture was washed with diethyl ether and dried under vacuum to obtain carboxytriazolinone, which was stored under an inert atmosphere at -20°C.

[0075] The preparation method of the hydroxyl-terminated hyperbranched polyester in this embodiment is as follows: Weigh 0.67 g of trimethylolpropane and 6.04 g of 2,2-dimethylolpropionic acid into a 250 mL round-bottom flask, add 5 mL of DMF, and sonicate until completely dissolved. Under ice bath and magnetic stirring, inject DCC solution (1.856 g of DCC dissolved in 5 mL of DMF) into the flask at a rate of 1 mL / h using a micro-injection pump. After injection, stir the reaction mixture under ice bath for 4 h. Centrifuge the reaction mixture, add 1 mL of deionized water to the supernatant, and repeat 3-5 times. Then place the supernatant in a 4 °C refrigerator and let it stand overnight. Centrifuge and repeat the operation until no precipitate dissolves. Remove the solvent from the supernatant by rotary evaporation and dry under vacuum at 80 °C to obtain the terminal hydroxyl hyperbranched polyester.

[0076] Comparative Example 1 The antistatic powder coating in this comparative example comprises the following components by weight: 600g modified epoxy resin, 30g curing agent, 100g composite conductive filler, 10g leveling agent, 5g defoamer, and 300g pigments and fillers.

[0077] The preparation method of the antistatic powder coating in this comparative example is the same as that in Example 2.

[0078] The preparation method of the modified epoxy resin in this comparative example is the same as that in Example 2.

[0079] The preparation method of the composite conductive filler in this comparative example is the same as that in Example 2.

[0080] The preparation method of the hyperbranched functional polymer in this comparative example is as follows: A1, 0.65g of hydroxyl-terminated hyperbranched polyester, 0.144g of pyrene-butyric acid, 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added, and the mixture was stirred and reacted for 5h under nitrogen protection. After washing and drying, pyrene-butyric acid-hyperbranched polyester was obtained.

[0081] A2, 0.165g of carboxytriazolinidone and the previous product pyrene-butyric acid-hyperbranched polyester were dissolved in 30mL of dichloromethane, and 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT were added. Under nitrogen protection, the mixture was stirred and reacted for 5h. After washing and drying, the hyperbranched functional polymer was obtained.

[0082] The preparation method of the carboxytriazolinidone in this comparative example is the same as that in Example 2.

[0083] The preparation method of the hydroxyl-terminated hyperbranched polyester in this comparative example is the same as that in Example 2.

[0084] Comparative Example 2 The antistatic powder coating in this comparative example comprises the following components by weight: 600g modified epoxy resin, 30g curing agent, 100g composite conductive filler, 10g leveling agent, 5g defoamer, and 300g pigments and fillers.

[0085] The preparation method of the antistatic powder coating in this comparative example is the same as that in Example 2.

[0086] The preparation method of the composite conductive filler in this comparative example is the same as that in Example 2.

[0087] The preparation method of the hyperbranched functional polymer in this comparative example is as follows: Take 0.65g of hydroxyl-terminated hyperbranched polyester, add 0.144g of pyrene butyric acid, 0.192g of EDCI, 0.122g of DMAP and 0.135g of HOBT, stir and react for 5h under nitrogen protection, then wash and dry to obtain hyperbranched functional polymer.

[0088] The preparation method of the hydroxyl-terminated hyperbranched polyester in this comparative example is the same as that in Example 2.

[0089] Performance testing Antistatic powder coating was electrostatically sprayed onto the substrate, cured to obtain a conductive coating, and then tested. Samples were prepared according to standard DL-1000B. The samples were fractured under a tensile load of 5 mm / min, and the fractured samples were then clamped together and left at room temperature for 24 hours. The morphology of the fracture site was then observed. Resistivity was tested according to GB / T 1410-89 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials"; impact performance of the coating was tested according to GB / T 1732-1993 "Test Method for Impact Resistance of Paint Films"; and adhesion of the coating was tested according to GB / T9286-1998 "Cross-cut Test for Paints and Varnishes".

[0090] Analyze Examples 1-3 and Comparative Examples 1-2, in conjunction with Table 1, Figure 1 It can be seen that by linking pyrene-butyric acid-polyethylene glycol-triazolidinedione dispersed carbon nanotubes with hyperbranched polyester and using indole-modified epoxy resin, conductive carbon nanotubes are uniformly dispersed in epoxy resin, and mechanoresponsive repair bonds are constructed, which enables the antistatic powder coating to have good antistatic, impact resistance, high adhesion and self-healing properties.

[0091] analyze Figure 1 As shown in Table 1, the antistatic powder coating prepared in Comparative Example 1, compared to Examples 1-3, did not contain polyethylene glycol chains, making it difficult to effectively and dynamically disperse carbon nanotubes, resulting in a decrease in its antistatic ability. Consequently, the volume resistivity of the antistatic powder coating in Comparative Example 1 increased significantly. The antistatic powder coating prepared in Comparative Example 2, compared to Examples 1-3, did not contain polyethylene glycol and triazolinone, and did not modify the epoxy resin, making it difficult to form mechanoresponsive repair bonds. Simultaneously, the dispersion of carbon nanotubes weakened, leading to an increase in the volume resistivity, a decrease in impact height, and a significant decrease in adhesion of the antistatic powder coating in Comparative Example 2. Figure 1 Compared to Example 2, obvious cracks can still be seen in the middle.

[0092] Table 1. Performance test results of antistatic powder coatings in Examples 1-3 and Comparative Examples 1-2 Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An antistatic powder coating, characterized in that, The product comprises the following components by weight: 35-60 parts modified epoxy resin, 2-3 parts curing agent, 5-20 parts composite conductive filler, 0.7-1.5 parts leveling agent, 0.3-1 part defoamer, and 10-30 parts pigments and fillers. The modified epoxy resin is prepared from indole-modified epoxy resin; The composite conductive filler is made of carbon nanotubes and hyperbranched functional polymers. The hyperbranched functional polymer is prepared from hydroxyl-terminated hyperbranched polyester, pyrene butyric acid, amino-terminated polyethylene glycol, and carboxylated triazoline dione.

2. The antistatic powder coating according to claim 1, characterized in that, The preparation method of the modified epoxy resin includes the following steps: reacting epoxy resin, 5-methoxytryptamine and N,N-dimethyl-1,6-hexanediamine to obtain the modified epoxy resin.

3. The antistatic powder coating according to claim 1, characterized in that, The preparation method of the composite conductive filler includes the following steps: carbon nanotubes and hyperbranched functional polymers are ultrasonically dispersed and composited in a solvent, and then separated and dried to obtain the filler.

4. The antistatic powder coating according to claim 3, characterized in that, The mass ratio of the carbon nanotubes to the hyperbranched functional polymer is 1:3-5.

5. The antistatic powder coating according to claim 1, characterized in that, The preparation method of the hyperbranched functional polymer includes the following steps: A1, amide condensation reaction of amino-terminated polyethylene glycol with pyrene butyric acid to obtain pyrene butyric acid-polyethylene glycol; A2, amide condensation reaction of pyrene butyric acid-polyethylene glycol with carboxylated triazolinone to obtain pyrene butyric acid-polyethylene glycol-triazolinone; A3, esterification reaction of hydroxyl-terminated hyperbranched polyester with pyrene butyric acid-polyethylene glycol-triazolinone to obtain the hyperbranched functional polymer.

6. The antistatic powder coating according to claim 5, characterized in that, In A1, the preparation method of terminal amino polyethylene glycol includes the following steps: B1, polyethylene glycol reacts with TsCl to obtain polyethylene glycol p-toluenesulfonate; B2, polyethylene glycol p-toluenesulfonate reacts with concentrated nitric acid under reflux to obtain terminal amino polyethylene glycol.

7. The antistatic powder coating according to claim 5, characterized in that, In A2, the preparation method of carboxytriazolinidone includes the following steps: C1, diphenyl carbonate and ethyl carbamate are reacted by heating and stirring to obtain dicarboxylic acid ethylphenylhydrazine; C2, L-glutamic acid-5-tert-butyl ester and dicarboxylic acid ethylphenylhydrazine are reacted by triethylamine to obtain aminourea; C3, aminourea is cyclized by K2CO3, MgSO4 and N2O4 to obtain tert-butyl ester-protected carboxytriazolinidone; C4, tert-butyl ester-protected carboxytriazolinidone is deprotected by trifluoroacetic acid, dichloromethane and triethylsilane to obtain carboxytriazolinidone.

8. The antistatic powder coating according to claim 5, characterized in that, The preparation method of the terminal hydroxyl hyperbranched polyester in A3 includes the following steps: trimethylolpropane and 2,2-dimethylolpropionic acid are reacted by DCC catalysis to obtain the terminal hydroxyl hyperbranched polyester.

9. A method for preparing an antistatic powder coating as described in any one of claims 1-8, characterized in that, The process includes the following steps: S1, first dry-mix the composite conductive filler with pigments and fillers, then add the remaining components to a high-speed mixer for premixing; S2, after mixing, feed the mixture into a twin-screw extruder to form a uniform melt; S3, feed the molten coating into a sheet-making machine to form sheets, then feed the formed sheet material into a grinding hopper for grinding and pulverizing, and finally grade and sieve to obtain an antistatic powder coating.

10. The method for preparing an antistatic powder coating according to claim 9, characterized in that, In S2, the temperature of each section of the twin-screw extruder is controlled at 100-110℃, with the feeding section temperature set at 100-105℃, and the middle section and die head section gradually increasing to 105-110℃.

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