A method for preparing an insulating anticorrosive powder coating

Abstract

The application relates to the technical field of insulating anticorrosive powder coating, and discloses a preparation method of insulating anticorrosive powder coating. Phenol formaldehyde modified epoxy resin bisphenol A type epoxy resin, polyurethane insulating anticorrosive agent, dicyandiamide imidazole accelerator, epoxy acetylpropyl phenol, mica powder, methyl methacrylate leveling agent, pure benzoin defoaming agent and pigment are uniformly mixed, stirred, added into a double-screw extruder for extrusion and tabletting, and then crushed through a high-speed crusher; after the powder is screened through a screen, the insulating anticorrosive powder coating is obtained. The anticorrosive coating forms a dense coating film on the base material, the corrosion medium is isolated from the metal base material, the coating is insulating and has no electric leakage phenomenon, and the base material can be guaranteed to have better corrosion resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of insulating anticorrosive powder coatings, in particular to a preparation method of insulating anticorrosive powder coatings. BACKGROUND

[0002] Powder coatings are completely different from general coatings, and exist in the form of fine powder. Since no solvent is used, the powder coatings are called powder coatings. The powder coatings can be manufactured by using synthetic resins with large molecular weight which are insoluble in solvents or water at normal temperature, so that denser coating films can be prepared, and the powder coatings have the characteristics of harmlessness, high efficiency, resource saving and environmental protection.

[0003] The thermosetting powder coating refers to a coating layer which is insoluble and hard in texture and can be formed by adding a curing agent for cross-linking reaction after heating, and the coating layer cannot be softened like a thermoplastic coating layer even at high temperature, but can only be decomposed. Since the resin used in the thermosetting powder coating is a prepolymer with low polymerization degree and low molecular weight, the leveling property of the coating layer is good.

[0004] Bus ducts, battery tanks, motor rotors, electromagnetic coils and some household appliances for installing cables often come into contact with chemical solvents, and at the same time, good electrical insulation is required. However, the epoxy powder coatings currently used cannot simultaneously meet the requirements of corrosion resistance and electrical insulation, which greatly limits the use of the powder coatings. SUMMARY

[0005] (I) Technical problems solved

[0006] In view of the defects of the prior art, the application provides a preparation method of insulating anticorrosive powder coatings, which solves the problems of poor corrosion resistance and poor insulation.

[0007] (II) Technical scheme

[0008] In order to achieve the above-mentioned purpose, the application provides the following technical scheme: a preparation method of insulating anticorrosive powder coatings, which comprises the following steps: uniformly mixing 20-30 parts by weight of phenolic modified epoxy resin, 10-15 parts by weight of bisphenol A type epoxy resin, 15-20 parts by weight of polyurethane insulating anticorrosive agent, 5-8 parts by weight of dicyandiamide imidazole accelerator, 6-10 parts by weight of curing agent, 3-5 parts by weight of mica powder, 2-4 parts by weight of methacrylate leveling agent, 1-3 parts by weight of pure benzoin defoaming agent and 1-2 parts by weight of pigment, stirring for 30-50 min, then adding into a double-screw extruder for extrusion and tabletting, and then crushing by a high-speed crusher, and screening the powder through a 120-150 mesh screen to obtain the insulating anticorrosive powder coatings.

[0009] Preferably, the preparation method of the polyurethane insulation anticorrosive agent is as follows:

[0010] (1) 15-20 parts by weight of the purified polyurethane particles and 10-12 parts by weight of dimethylformamide are added into a reactor, stirred and dissolved at 60-90°C, left for 3-4h, filtered and dried, first dried at 60-80°C for 20-22h, and then dried at 30-40°C for 22-24h to obtain polyurethane film;

[0011] (2) 8-12 parts by weight of methyl isothiocyanate methacrylate is added into a reactor equipped with a magnetic stirrer and 6-8 parts by weight of polyurethane film, protected by nitrogen, sealed with a film, and subjected to oil bath at 60-80°C, then 0.1-0.4 parts by weight of triethylamine is slowly added, reacted for 10-15h, washed with acetonitrile by ultrasonic for 2-4 times after the reaction, and dried to obtain methyl isothiocyanate methacrylate grafted polyurethane;

[0012] (3) The methyl isothiocyanate methacrylate grafted polyurethane is dissolved in N,N-dimethylformamide solvent, then acrylic acid and azobisisobutyronitrile are added, and subjected to polymerization reaction at 60-80°C for 6-12h to obtain carboxyl-polyurethane polymer;

[0013] (4) The carboxyl-polyurethane polymer is added into triethylamine, stirred uniformly, then added with thionyl chloride, and reacted at 70-90°C for 4-7h, then precipitated after adding acetone after the reaction, filtered and washed with acetone to obtain acryloyl chloride-polyurethane polymer;

[0014] (5) 2-mercaptobenzothiazole is added into toluene solvent, stirred and dissolved, then the acryloyl chloride-polyurethane polymer is added at 2-6°C, stirred for 30-50min, then reacted at 60-80°C for 2-4h, then the solvent is removed by distillation under reduced pressure after the reaction, filtered, washed and dried to obtain the polyurethane insulation anticorrosive agent.

[0015] Preferably, the weight ratio of the methyl isothiocyanate methacrylate grafted polyurethane, acrylic acid and azobisisobutyronitrile in (3) is 2.1-3.2:1:0.02-0.04.

[0016] Preferably, the weight ratio of the carboxyl-polyurethane polymer and thionyl chloride in (4) is 1.3-1.5:1.

[0017] Preferably, the weight ratio of the 2-mercaptobenzothiazole and acryloyl chloride-polyurethane polymer in (5) is 1.6-1.8:1.

[0018] Preferably, the bisphenol A epoxy resin has an epoxy equivalent weight of 750-900g / eq and a softening point of 90-110°C.

[0019] Preferably, the curing agent is any one of epoxy acetyl propyl phenol, catechol, m-cresol.

[0020] Preferably, the pigment is any one of phthalocyanine blue, medium chrome yellow, permanent red, permanent purple.

[0021] (III) Beneficial technical effects

[0022] The present application mixes uniformly phenolic modified epoxy resin bisphenol A type epoxy resin, polyurethane insulation anticorrosive agent, dicyandiamide imidazole accelerator, epoxy acetyl propyl phenol, mica powder, methacrylate leveling agent, pure benzoin defoaming agent, pigment, stirring, then adding to the double screw extruder extrusion tablet, then passing through the high speed pulverizer for crushing, the powder is sieved through the screen, to obtain the insulation anticorrosive powder coating.

[0023] The present application forms a dense coating film on the substrate by the anticorrosive coating, isolates the corrosion medium from the metal substrate, and the coating is insulated without leakage phenomenon, which can ensure that the substrate has better corrosion resistance; the polyurethane insulation anticorrosive agent contains a large amount of 2-mercapto benzothiazole, which has good corrosion prevention effect and cooperates with polyurethane and epoxy resin to have insulation anticorrosive effect. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a polyurethane insulation anticorrosive agent reaction formula. DETAILED DESCRIPTION

[0025] Example 1

[0026] (1) 15g of purified polyurethane particles and 10g of dimethylformamide were added to a reactor, stirred and dissolved at 60℃, and then placed for 3h, filtered and dried, first dried at 60℃ for 20h, and then dried at 30℃ for 22h, to obtain a polyurethane film;

[0027] (2) 8g of methyl isothiocyanate methacrylate was added to a reactor containing a magnetic sub and 6g of polyurethane film, protected by nitrogen, sealed with a film, and then 0.1g of triethylamine was slowly added, reacted for 10h, and then acetonitrile was used for ultrasonic washing for 2 times, and dried, to obtain methyl isothiocyanate methacrylate grafted polyurethane;

[0028] (3) 2.1g of methyl isothiocyanate methacrylate grafted polyurethane was added to N,N-dimethylformamide solvent for dissolution, then 1g of acrylic acid and 0.02g of azobisisobutyronitrile were added, and polymerization reaction was carried out at 60℃ for 6h, to obtain carboxyl-polyurethane polymer;

[0029] (4) 1.3 g of carboxyl-polyurethane polymer was added to triethylamine, stirred to be uniform, then 1 g of thionyl chloride was added, reacted at 70°C for 4 h, after the reaction, acetone was added to precipitate, the solvent was filtered, washed with acetone, to obtain acryloyl chloride-polyurethane polymer;

[0030] (5) 1.6 g of 2-sulfo benzothiazole was added to toluene solvent, stirred to be dissolved, then 1 g of acryloyl chloride-polyurethane polymer was added at 2°C, stirred for 30 min, then reacted at 60°C for 2 h, after the reaction, the solvent was removed by distillation under reduced pressure, filtered, washed and dried, to obtain polyurethane insulating anticorrosive agent;

[0031] (6) 20 g of phenolic modified epoxy resin, 10 g of bisphenol A type epoxy resin, the epoxy equivalent weight of bisphenol A epoxy resin was 750 g / eq, the softening point was 90°C, 15 g of polyurethane insulating anticorrosive agent, 5 g of dicyandiamide imidazole accelerator, 6 g of epoxy acetylpropyl phenol, 3 g of mica powder, 2 g of methacrylate leveling agent, 1 g of pure benzoin antifoaming agent, 1 g of medium chrome yellow, were mixed uniformly, stirred for 30 min, then added to a twin-screw extruder for extrusion and tabletting, then crushed by a high-speed crusher, the powder was sieved through a 120 mesh screen, to obtain insulating anticorrosive powder coating.

[0032] Example 2

[0033] (1) 20 g of purified polyurethane particles and 12 g of dimethylformamide were added to a reactor, stirred to be dissolved at 90°C, stood for 4 h, filtered and dried, first dried at 80°C for 22 h, then dried at 40°C for 24 h, to obtain polyurethane film;

[0034] (2) 12 g of isothiocyanate methacrylate was added to a reactor equipped with a magnetic stirrer and 8 g of polyurethane film, protected by nitrogen gas, sealed with a film, subjected to oil bath at 80°C, then 0.4 g of triethylamine was slowly added, reacted for 15 h, after the reaction, washed with acetonitrile for 4 times, dried, to obtain isothiocyanate methacrylate grafted polyurethane;

[0035] (3) 6.4 g of isothiocyanate methacrylate grafted polyurethane was added to N,N-dimethylformamide solvent for dissolution, then 2 g of acrylic acid and 0.08 g of azobisisobutyronitrile were added, subjected to polymerization reaction at 80°C for 12 h, to obtain carboxyl-polyurethane polymer;

[0036] (4) 3 g of carboxyl-polyurethane polymer was added to triethylamine, stirred to be uniform, then 2 g of thionyl chloride was added, reacted at 90°C for 7 h, after the reaction, acetone was added to precipitate, the solvent was filtered, washed with acetone, to obtain acryloyl chloride-polyurethane polymer;

[0037] (5) 2.6 g of 2-mercapto benzothiazole was added to toluene solvent and stirred to dissolve, then 1.5 g of acryloyl chloride-polyurethane polymer was added at 4°C and stirred for 40 min, then reacted at 70°C for 3 h, after the reaction, the solvent was removed by distillation under reduced pressure, filtered, washed and dried to obtain a polyurethane insulating anticorrosive agent;

[0038] (6) 30 g of phenolic modified epoxy resin, 15 g of bisphenol A type epoxy resin with an epoxy equivalent weight of 900 g / eq and a softening point of 110°C, 20 g of polyurethane insulating anticorrosive agent, 8 g of dicyandiamide imidazole accelerator, 10 g of catechol, 5 g of mica powder, 4 g of methacrylate leveling agent, 3 g of pure benzoin antifoaming agent, and 2 g of permanent red were mixed uniformly and stirred for 50 min, then added to a twin-screw extruder for extrusion and tabletting, and then crushed by a high-speed crusher, and the powder was sieved through a 150 mesh screen to obtain an insulating anticorrosive powder coating.

[0039] Example 3

[0040] (1) 17.5 g of purified polyurethane particles and 11 g of dimethylformamide were added to a reactor and stirred to dissolve at 75°C, and then allowed to stand for 3.5 h, filtered and dried, first at 70°C for 21 h, and then at 35°C for 23 h, to obtain a polyurethane film;

[0041] (2) 10 g of methacrylisothiocyanate was added to a reactor containing a magnetic stirrer and 7 g of polyurethane film, protected by nitrogen gas, sealed with a film, and then 0.25 g of triethylamine was slowly added, and reacted at 70°C for 12.5 h, after which the reaction was completed, the acetonitrile was washed ultrasonically for 3 times, and dried to obtain methacrylisothiocyanate grafted polyurethane;

[0042] (3) 4.25 g of methacrylisothiocyanate grafted polyurethane was added to N,N-dimethylformamide solvent and dissolved, then 1.5 g of acrylic acid and 0.05 g of azobisisobutyronitrile were added, and polymerized at 70°C for 9 h to obtain a carboxyl-polyurethane polymer;

[0043] (4) 2.15 g of carboxyl-polyurethane polymer was added to triethylamine, stirred to dissolve, then 1.5 g of thionyl chloride was added, and reacted at 80°C for 5.5 h, after which the reaction was completed, the precipitate was obtained by adding acetone, and the solvent was filtered and washed with acetone to obtain an acryloyl chloride-polyurethane polymer;

[0044] (5) 2.6 g of 2-mercapto benzothiazole was added to toluene solvent and stirred to dissolve, then 1.5 g of acryloyl chloride-polyurethane polymer was added at 4°C and stirred for 40 min, then reacted at 70°C for 3 h, after the reaction, the solvent was removed by distillation under reduced pressure, filtered, washed and dried to obtain a polyurethane insulating anticorrosive agent;

[0045] (6) 25 g of phenolic modified epoxy resin, 12.5 g of bisphenol A type epoxy resin with an epoxy equivalent weight of 825 g / eq and a softening point of 100°C, 17.5 g of polyurethane insulating anticorrosive agent, 6.5 g of dicyandiamide imidazole accelerator, 8 g of m-cresol, 4 g of mica powder, 3 g of methacrylate leveling agent, 2 g of pure benzoin antifoaming agent, and 1.5 g of permanent purple are uniformly mixed, stirred for 40 min, then added to a double-screw extruder for extrusion and tabletting, and then crushed by a high-speed crusher. After the powder is sieved through a 135-mesh screen, an insulating anticorrosive powder coating is obtained.

[0046] Example 4

[0047] (1) 15 g of purified polyurethane particles and 10 g of dimethylformamide are added to a reactor, dissolved by stirring at 60°C, and left to stand for 3 h. After filtration and drying, the polyurethane film is first dried at 60°C for 20 h and then at 30°C for 22 h;

[0048] (2) 8 g of isothiocyanate methacrylate is added to a reactor containing a magnetic stirrer and 6 g of polyurethane film, protected by nitrogen gas, sealed with a film, and subjected to an oil bath at 60°C. Then, 0.1 g of triethylamine is slowly added, and the reaction is carried out for 10 h. After the reaction, the product is washed with acetonitrile twice by ultrasonic treatment and dried to obtain isothiocyanate methacrylate grafted polyurethane;

[0049] (3) 6.4 g of isothiocyanate methacrylate grafted polyurethane is dissolved in N,N-dimethylformamide solvent, and then 2 g of acrylic acid and 0.08 g of azobisisobutyronitrile are added. The polymerization reaction is carried out at 80°C for 12 h to obtain carboxyl-polyurethane polymer;

[0050] (4) 3 g of carboxyl-polyurethane polymer is added to triethylamine, stirred uniformly, and then 2 g of thionyl chloride is added. The reaction is carried out at 90°C for 7 h. After the reaction, the precipitate is separated by filtration, and washed with acetone to obtain acryloyl chloride-polyurethane polymer;

[0051] (5) 2.6 g of 2-sulfenyl benzothiazole is added to toluene solvent and stirred to dissolve. Then, 1.5 g of acryloyl chloride-polyurethane polymer is added at 4°C and stirred for 40 min. Then, the reaction is carried out at 70°C for 3 h. After the reaction, the solvent is removed by distillation under reduced pressure, and the product is filtered, washed, and dried to obtain polyurethane insulating anticorrosive agent;

[0052] (6) 25 g of phenolic modified epoxy resin, 12.5 g of bisphenol A type epoxy resin with an epoxy equivalent weight of 825 g / eq and a softening point of 100°C, 17.5 g of polyurethane insulating anticorrosive agent, 6.5 g of dicyandiamide imidazole accelerator, 8 g of m-cresol, 4 g of mica powder, 3 g of methacrylate leveling agent, 2 g of pure benzoin antifoaming agent, and 1.5 g of fast violet were mixed uniformly, stirred for 40 min, then added to a double-screw extruder for extrusion and tabletting, and then crushed by a high-speed crusher. After the powder was sieved through a 135-mesh screen, an insulating anticorrosive powder coating was obtained.

[0053] Example 5

[0054] (1) 20 g of purified polyurethane particles and 12 g of dimethylformamide were added to a reactor, dissolved by stirring at 90°C, and left to stand for 4 h. After filtration and drying, the polyurethane film was dried at 80°C for 22 h and then at 40°C for 24 h;

[0055] (2) 12 g of isothiocyanate methacrylate was added to a reactor containing a magnetic stirrer and 8 g of the polyurethane film, protected by nitrogen gas, sealed with a film, and subjected to an oil bath at 80°C. Then, 0.4 g of triethylamine was slowly added, and the reaction was carried out for 15 h. After the reaction, the isothiocyanate methacrylate grafted polyurethane was washed with acetonitrile four times by ultrasonic treatment and dried;

[0056] (3) 4.25 g of the isothiocyanate methacrylate grafted polyurethane was dissolved in N,N-dimethylformamide solvent, and then 1.5 g of acrylic acid and 0.05 g of azobisisobutyronitrile were added. The polymerization reaction was carried out at 70°C for 9 h to obtain a carboxyl-polyurethane polymer;

[0057] (4) 2.15 g of the carboxyl-polyurethane polymer was added to triethylamine, stirred uniformly, and then 1.5 g of thionyl chloride was added. The reaction was carried out at 80°C for 5.5 h. After the reaction, the acryloyl chloride-polyurethane polymer was obtained by precipitating the product with acetone, filtering the solvent, and washing with acetone;

[0058] (5) 1.6 g of 2-mercapto benzothiazole was dissolved in toluene solvent by stirring, and then 1 g of the acryloyl chloride-polyurethane polymer was added at 2°C and stirred for 30 min. The reaction was carried out at 60°C for 2 h. After the reaction, the solvent was removed by distillation under reduced pressure, and the polyurethane insulating anticorrosive agent was obtained by filtration, washing, and drying;

[0059] (6) 20g phenolic modified epoxy resin, 10g bisphenol A type epoxy resin, bisphenol A epoxy resin epoxy equivalent in 750g / eq, softening point of 90℃, 15g polyurethane insulation anticorrosive agent, 5g dicyandiamide imidazole accelerator, 6g epoxy acetyl propyl phenol, 3g mica powder, 2g methacrylate leveling agent, 1g pure benzoin defoamer, 1g medium chrome yellow, mixed evenly, stirred for 30min, then added to the twin screw extruder extrusion tablet, then crushed by high speed crusher, the powder is sieved through 120 mesh screen, get insulation anticorrosive powder coating.

[0060] Comparative example 1

[0061] (1) 20g phenolic modified epoxy resin, 10g bisphenol A type epoxy resin, bisphenol A epoxy resin epoxy equivalent in 750g / eq, softening point of 90℃, 5g dicyandiamide imidazole accelerator, 6g epoxy acetyl propyl phenol, 3g mica powder, 2g methacrylate leveling agent, 1g pure benzoin defoamer, 1g medium chrome yellow, mixed evenly, stirred for 30min, then added to the twin screw extruder extrusion tablet, then crushed by high speed crusher, the powder is sieved through 120 mesh screen, get insulation anticorrosive powder coating.

[0062] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details, nor limit the present application to the specific embodiments described. Obviously, according to the content of the present application, many modifications and changes can be made. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A process for the production of an insulating anticorrosive powder coating, characterized in that, Comprising the following steps: S1. 20-30 parts by weight of phenolic modified epoxy resin, 10-15 parts by weight of bisphenol A type epoxy resin, 15-20 parts by weight of polyurethane insulation anticorrosive agent, 5-8 parts by weight of dicyandiamide imidazole accelerator, 6-10 parts by weight of curing agent, 3-5 parts by weight of mica powder, 2-4 parts by weight of methacrylate leveling agent, 1-3 parts by weight of pure benzoin antifoaming agent, 1-2 parts by weight of pigment, are mixed uniformly, stirred for 30-50 min, then added to a double screw extruder for extrusion and tabletting, then crushed by a high speed crusher, the powder is sieved through a 120-150 mesh screen to obtain an insulation anticorrosive powder coating; The preparation method of the polyurethane insulation anticorrosive agent is: (1) 15-20 parts by weight of purified polyurethane particles and 10-12 parts by weight of dimethylformamide are added to a reactor, stirred and dissolved at 60-90°C, and then left to stand for 3-4 h, filtered and dried, first dried at 60-80°C for 20-22 h, and then dried at 30-40°C for 22-24 h to obtain polyurethane film; (2) 8-12 parts by weight of methyl isothiocyanate methacrylate is added to a reactor containing a magnetic stirrer and 6-8 parts by weight of polyurethane film, protected by nitrogen gas, sealed with a film, and then slowly added with 0.1-0.4 parts by weight of triethylamine, reacted for 10-15 h, washed with acetonitrile for 2-4 times after the reaction, and dried to obtain methyl isothiocyanate methacrylate grafted polyurethane; (3) Methyl isothiocyanate methacrylate grafted polyurethane is dissolved in N,N-dimethylformamide solvent, then acrylic acid and azobisisobutyronitrile are added, and polymerization is carried out at 60-80°C for 6-12 h to obtain carboxyl-polyurethane polymer; (4) The carboxyl-polyurethane polymer is added to triethylamine, stirred uniformly, then added with thionyl chloride, and reacted at 70-90°C for 4-7 h, then added with acetone to precipitate the sediment, filtered the solvent, washed with acetone, and obtained acryloyl chloride-polyurethane polymer; (5) 2-Mercaptobenzothiazole is added to toluene solvent, stirred and dissolved, then added with acryloyl chloride-polyurethane polymer at 2-6°C, stirred for 30-50 min, then reacted at 60-80°C for 2-4 h, then removed the solvent by distillation under reduced pressure, filtered, washed and dried to obtain polyurethane insulation anticorrosive agent; The weight ratio of methyl isothiocyanate methacrylate grafted polyurethane, acrylic acid and azobisisobutyronitrile in (3) is 2.1-3.2:1:0.02-0.04; The weight ratio of carboxyl-polyurethane polymer and thionyl chloride in (4) is 1.3-1.5:1; The weight ratio of 2-mercaptobenzothiazole and acryloyl chloride-polyurethane polymer in (5) is 1.6-1.8:

1.

2. The process for the production of an insulating anticorrosive powder paint according to claim 1, characterized in that, The epoxy equivalent weight of the bisphenol A type epoxy resin is 750-900 g / eq, and the softening point is 90-110°C.

3. The method of claim 1, wherein the insulating anticorrosive powder coating is prepared by adding the anticorrosive pigment to the base resin and then adding the other components. The curing agent is any one of epoxy acetylpropyl phenol, ortho-phenylenediamine, and m-cresol.

4. The method of claim 1, wherein the insulating anticorrosive powder coating is prepared by adding the anticorrosive pigment to the base resin and then adding the other components. The pigments are any of phthalo blue, medium chrome yellow, permanent red, permanent violet. The pigments are any of phthalo blue, medium chrome yellow, permanent red, permanent violet.

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