阅读说明：本技术 一种耐磨隔热防腐粉末涂料的制备方法 (Preparation method of wear-resistant, heat-insulating and corrosion-resistant powder coating ) 是由 孙振龙 于 2019-10-09 设计创作，主要内容包括：本发明公开了一种耐磨隔热防腐粉末涂料的制备方法,该粉末涂料由以下原料制得：苯并噁嗪树脂、环氧树脂、氯化聚醚、端羧基丁腈橡胶、固化剂、重晶石粉、硅灰石粉。经过熔融混合挤出、冷却压片、破碎、过筛等工序即可制得耐磨隔热防腐粉末涂料,其具有优异的耐磨耐腐蚀隔热性能,经加工后的涂膜表面在附着力、柔韧性、冲击强度、光滑度、硬度和耐化学性等方面都符合国家及行业标准,且固化温度低,使用方便,降低成本。(The invention discloses a preparation method of a wear-resistant heat-insulating anticorrosive powder coating, which is prepared from the following raw materials: benzoxazine resin, epoxy resin, chlorinated polyether, carboxyl-terminated nitrile rubber, a curing agent, barite powder and wollastonite powder. The wear-resistant, heat-insulating and corrosion-resistant powder coating can be prepared by the processes of melt mixing extrusion, cooling tabletting, crushing, sieving and the like, has excellent wear-resistant, corrosion-resistant and heat-insulating properties, and the processed coating film surface meets the national and industrial standards in the aspects of adhesive force, flexibility, impact strength, smoothness, hardness, chemical resistance and the like, and is low in curing temperature, convenient to use and low in cost.)

1. The preparation method of the wear-resistant heat-insulating anticorrosive powder coating is characterized by comprising the following specific steps of: firstly, putting mercaptan and epoxy resin into a reaction kettle with a condenser pipe, heating, adding an acid catalyst for ring-opening reaction, wherein the reaction temperature is 30-40 ℃, and the ring-opening reaction time is 1-2.5 h, and the whole reaction process is carried out in a multi-frequency composite ultrasonic auxiliary device, wherein the multi-frequency composite ultrasonic auxiliary device is a three-frequency composite ultrasonic auxiliary device, and the axial ultrasonic frequency of the three-frequency composite ultrasonic auxiliary device is 28kHz and 48 kHz; the radial ultrasonic frequency is 35 kHz; sampling at regular time in the reaction process, measuring the epoxy value of the mixture, stopping the reaction when the epoxy value is not reduced any more, cooling the reaction system to room temperature, filtering and recovering a solid catalyst, putting the rest mixture into a reduced pressure distillation device to evaporate excessive mercaptan, then washing with hot alkali liquor with the mass fraction of 2% for 4-5 times, washing with water until the pH value is neutral, finally carrying out rotary evaporation and dehydration to obtain a light yellow product, mixing and heating the light yellow product obtained in the step one with benzoxazine resin to 70-80 ℃, adding a dispersing agent, stirring uniformly, adding chlorinated polyether powder, carboxyl-terminated butadiene-acrylonitrile rubber, barite powder and wollastonite powder, and stirring uniformly; and thirdly, after uniform mixing, adding the materials into a double-screw melt extruder, setting the temperature of a feeding section to be 105-110 ℃, setting the temperature of an extrusion section to be 110-115 ℃, uniformly dispersing the curing agent in the heating melt extrusion process, further pressing into thin slices, crushing the thin slices by a high-speed crusher after cooling, sieving the thin slices by a standard sieve, spraying a sample plate on the obtained powder by using a high-voltage electrostatic spray gun, putting the sample plate into a constant-temperature air-blast drying box, solidifying the sample plate at 200 ℃/20min, taking out the solidified sample plate, and.

2. The preparation method of the wear-resistant, heat-insulating and corrosion-resistant powder coating as claimed in claim 1, wherein the given proportion is composed of the following raw materials in parts by weight: 32-43 parts of benzoxazine, 54-61 parts of epoxy resin, 31-39 parts of chlorinated polyether, 9-16 parts of carboxyl-terminated nitrile rubber, 3-7 parts of curing agent, 16-23 parts of barite powder, 1-8 parts of wollastonite powder, 0.1-0.3 part of mercaptan and 0.05-0.2 part of acidic catalyst.

3. The preparation method of the wear-resistant, heat-insulating and corrosion-resistant powder coating according to claim 1, wherein the benzoxazine resin is benzoxazine resin with viscosity of 0.8-1.0 Pa-s and molecular weight of 850-2500.

4. The method for preparing the wear-resistant, heat-insulating and corrosion-resistant powder coating as claimed in claim 1, wherein the epoxy curing agent is aliphatic diamine, polyamine or aromatic polyamine.

5. The preparation method of the wear-resistant, heat-insulating and anti-corrosion powder coating as claimed in claim 1, wherein the carboxyl-terminated nitrile butadiene rubber is carboxyl-terminated nitrile butadiene rubber with a carboxyl content of 0.045-0.051%, an acrylonitrile content of 10-26% and a molecular weight of 3100-4200.

6. The preparation method of the wear-resistant, heat-insulating and corrosion-resistant powder coating as claimed in claim 1, wherein the dispersant is a mixture of epoxidized soybean oil, polyvinylpyrrolidone, sodium dodecylbenzenesulfonate and polyethylene glycol.

7. The preparation method of the wear-resistant, heat-insulating and anti-corrosion powder coating as claimed in claim 1, wherein the epoxy resin is bisphenol A epoxy resin and gamma-butyrolactone modified epoxy resin with softening point of 70-85 ℃ and epoxy value of 0.12-0.18.

Technical Field

The invention relates to the technical field of powder coatings, in particular to a preparation method of a wear-resistant, heat-insulating and anti-corrosion powder coating.

Background

Epoxy powder coatings were thermosetting powder coatings developed in the last century. The film forming material epoxy resin has excellent physical and mechanical properties, and the coating film has good adhesion to a substrate, good electrical insulation and excellent chemical corrosion resistance. The coating is widely applied to the internal and external corrosion prevention of chemical industry, electrical appliances, instruments, machinery and transportation pipelines, and occupies a leading position in anticorrosive coatings. However, due to the characteristics of the epoxy resin, the epoxy powder coating has poor weather resistance and abrasion resistance in practical application, and a coating film is easy to pulverize, so that the epoxy powder coating is not suitable for outdoor coating, and the application of the epoxy powder coating is limited. At present, in the field of corrosion resistance requiring weather resistance, a double-layer spraying method is generally adopted, namely a bottom layer anticorrosive coating and a surface layer weather-resistant coating, but the actual production process and the process control of the method are complex, and the conditions of poor interlayer adhesion, surface flowering and the like are easy to occur. Along with the enhancement of energy-saving and environment-friendly concepts of people, the national environment protection laws and regulations are more and more strict, the environment protection supervision storm is more and more strong, and the market is more and more urgent to need energy-saving, environment-friendly and green coatings. More and more end products are being coated with powder coatings. Thermosetting powder coatings are of various varieties and can be crosslinked and cured to form a film after being cured for a long time at high temperature of 210 ℃ for 10-20min and 180-. This makes the use of powder coatings limited and complicated to handle for certain substrates and the cost of use increases. Powder coating low temperature curing techniques have long received attention. Efforts have been continuously made over the years to achieve low temperature curing or rapid curing of powder coatings. This attempt is reflected in various resin systems: epoxy type, epoxy polyester type and polyester type have been developed, and the curing temperature is lowered or the curing time is shortened. The thermosetting powder coating has low melt viscosity, good leveling property, lower resin softening point and better pulverization property and dispersibility. The resin and the curing agent form a macromolecular network structure after being crosslinked, and an insoluble and infusible tough paint film can be formed. Therefore, thermosetting powder coatings have better corrosion resistance and adhesion than thermoplastic powder coatings, and are becoming the mainstream of powder coatings. However, thermosetting powder coatings must be baked at high temperatures to cure into films, which greatly limits their application. However, in terms of super durability, scratch resistance, fire resistance, electrical insulation, chemical resistance and the like in the marine and friction industrial environments, the novel wear-resistant, heat-insulating and corrosion-resistant powder coating inherits the excellent mechanical properties of impact resistance, flexibility, wear resistance and the like and unique surface touch feeling, and technical personnel in the field need to be developed to meet higher use requirements of people.

Disclosure of Invention

The invention aims to provide a preparation method of a wear-resistant, heat-insulating and anti-corrosion powder coating aiming at the existing problems.

A preparation method of wear-resistant heat-insulating anticorrosive powder coating comprises the following specific steps: firstly, putting mercaptan and epoxy resin into a reaction kettle with a condenser pipe, heating, adding an acid catalyst for ring-opening reaction, wherein the reaction temperature is 30-40 ℃, and the ring-opening reaction time is 1-2.5 h, and the whole reaction process is carried out in a multi-frequency composite ultrasonic auxiliary device, wherein the multi-frequency composite ultrasonic auxiliary device is a three-frequency composite ultrasonic auxiliary device, and the axial ultrasonic frequency of the three-frequency composite ultrasonic auxiliary device is 28kHz and 48 kHz; the radial ultrasonic frequency is 35 kHz; sampling at regular time in the reaction process, measuring the epoxy value of the mixture, stopping the reaction when the epoxy value is not reduced any more, cooling the reaction system to room temperature, filtering and recovering a solid catalyst, putting the rest mixture into a reduced pressure distillation device to evaporate excessive mercaptan, then washing with hot alkali liquor with the mass fraction of 2% for 4-5 times, washing with water until the pH value is neutral, finally carrying out rotary evaporation and dehydration to obtain a light yellow product, mixing and heating the light yellow product obtained in the step one with benzoxazine resin to 70-80 ℃, adding a dispersing agent, stirring uniformly, adding chlorinated polyether powder, carboxyl-terminated butadiene-acrylonitrile rubber, barite powder and wollastonite powder, and stirring uniformly; and thirdly, after uniform mixing, adding the materials into a double-screw melt extruder, setting the temperature of a feeding section to be 105-110 ℃, setting the temperature of an extrusion section to be 110-115 ℃, uniformly dispersing the curing agent in the heating melt extrusion process, further pressing into thin slices, crushing the thin slices by a high-speed crusher after cooling, sieving the thin slices by a standard sieve, spraying a sample plate on the obtained powder by using a high-voltage electrostatic spray gun, putting the sample plate into a constant-temperature air-blast drying box, solidifying the sample plate at 200 ℃/20min, taking out the solidified sample plate, and.

Further, the predetermined proportion is composed of the following raw materials in parts by weight: 32-43 parts of benzoxazine, 54-61 parts of epoxy resin, 31-39 parts of chlorinated polyether, 9-16 parts of carboxyl-terminated nitrile rubber, 3-7 parts of curing agent, 16-23 parts of barite powder, 1-8 parts of wollastonite powder, 0.1-0.3 part of mercaptan and 0.05-0.2 part of acidic catalyst.

Furthermore, the benzoxazine resin is benzoxazine resin with viscosity of 0.8-1.0 Pa.s and molecular weight of 850-2500.

Further, the epoxy curing agent is aliphatic diamine, polyamine or aromatic polyamine.

Furthermore, the carboxyl-terminated nitrile rubber is carboxyl-terminated nitrile rubber with the carboxyl content of 0.045-0.051%, the acrylonitrile content of 10-26% and the molecular weight of 3100-4200.

Further, the dispersing agent is a mixture of epoxidized soybean oil, polyvinylpyrrolidone, sodium dodecyl benzene sulfonate and polyethylene glycol.

Further, the epoxy resin is bisphenol A epoxy resin and gamma-butyrolactone modified epoxy resin with the softening point of 70-85 ℃ and the epoxy value of 0.12-0.18.

The invention has the beneficial effects that:

the benzoxazine used in the invention generates cross-linking reaction among the introduced resin active functional groups, and the obtained modified coating film has the advantages of strong epoxy adhesive force, large flexibility and good alkali resistance, and has the characteristics of good water resistance, solvent resistance and acid resistance. The reaction activity is moderate, and the low-temperature curing can be realized under the coordination of the accelerator; the compatibility with bisphenol A epoxy resin is good, the coating film has high glossiness, and the glossiness can be still high by low-temperature curing; the melt viscosity is low, and the wettability and leveling property are good; the cross-linking density of the coating is moderate, and the physical and mechanical properties are good. The temperature of the mixing section of the extruder is preferably set to be 110-115 ℃, so that uniform mixing is ensured, and gelled particles are not generated.

Compared with the prior art, the invention has the following advantages:

the benzoxazine resin has groups capable of reacting with epoxy groups and hydroxyl groups in the epoxy resin, can be mutually crosslinked to generate curing under certain conditions, has a complex process, and can react with phenolic hydroxyl groups in the benzoxazine resin and epoxy groups in an etherification reaction, generated new hydroxyl groups can react with epoxy groups, hydroxymethyl groups in the benzoxazine resin react with hydroxyl groups in the epoxy resin, and hydroxymethyl groups in the benzoxazine resin react with epoxy groups in the epoxy resin. Finally, the benzoxazine resin can be crosslinked into a complex integral structure product, and the product not only has the excellent acid resistance of the benzoxazine resin, but also has the alkali resistance and the adhesive property of the epoxy resin, and can also improve the temperature resistance of the simple epoxy resin. And no micromolecular volatile matters are discharged during the curing of the benzoxazine, so that the phenomenon that an accelerating agent and a curing agent are permeated and transferred to the surface of a high polymer material in the cross-linking and curing process of the epoxy resin is greatly reduced. Thereby improving the corrosion resistance and the wear resistance of the coating.

The surface of the coating is easy to have a surface film formed by adding a dispersant, a diluent, a release agent, an antistatic agent and the like in the forming process, the coating is extremely easy to be polluted by oil stains and dust, water molecules can be adsorbed on the surface of the coating, and the surface of the coating can be degraded or decomposed under the influence of temperature, stress, water, oxygen, radiation and the like to generate low molecular weight products and the like. A surface film which can make the coating generate a certain lubricating effect. The introduction of the wollastonite powder improves the wear-resistant life of the composite coating and the coating, and the wollastonite powder is used as a flaky nano filler with extremely high mechanical strength to improve the bearing capacity of the polymer, thereby improving the wear-resistant performance of the composite coating. The abrasion resistance of the coating is reduced to a certain extent. In addition, the benzoxazine resin is introduced from the wear-resistant life of the coating, so that the relative fluctuation of the wear life of the benzoxazine resin can be weakened, and the coating material with relatively stable wear-resistant performance is obtained.

The addition of the solid lubricant can obviously improve the friction performance of the coating and obviously reduce the friction coefficient, and the wollastonite powder and the barite powder which are used as flaky nano-fillers with extremely high mechanical strength form abrasive particles in the friction process to generate abrasive particle abrasion, so that the friction coefficient is increased to a certain extent. With the increase of the content of the graphene, although the fatigue wear of the composite coating occurs, the wear resistance is reduced to a certain extent. However, in this case, a large amount of abrasive dust containing a filler is present between the friction pair, and a certain amount of coating film having a lubricating effect is formed by the friction action, and the friction coefficient may be lowered.

The hydroxyl of the epoxy resin reacts with the hydroxymethyl of the benzoxazine crosslinking agent, the self-condensation tendency of the curing agent is small, and the dispersing agent with special composition also participates in the crosslinking and curing of the coating; during the use process, due to medium erosion, substances in the coating are dissolved and seeped to form channel nano oxides, so that the hydrophobicity of the surface of the coating can be improved, the capillary pores of the coating can be blocked, the corrosion resistance of the coating, particularly the corrosion resistance of the corners of a workpiece, can be improved, and the technology is introduced into the wear-resistant heat-insulating anticorrosive coating, so that the corrosion resistance, the mechanical property and the heat resistance of the coating can be further improved.

The wear-resistant high-heat-resistant anticorrosive powder coating disclosed by the invention expands the application range of the powder coating, has a very obvious energy-saving effect, and has great economic and social benefits. And (3) more efficient coating: the low temperature and the fast solidification meet the requirement of high-efficiency operation of a coating production line. Reducing damage to the substrate: the low temperature can reduce the warping of the plate, the cracking of the glass and the aging of the plastic. Better color and light retention of the coating film: the low-temperature curing enables the color of the coating film to be more vivid and the luster to be fuller.

Detailed Description

The invention is illustrated by the following specific examples, which are not intended to be limiting.