High-solid-content super-weather-resistant epoxy zinc-rich primer and preparation method thereof

Abstract

The invention discloses a high-solid-content super-weather-resistant epoxy zinc-rich primer and a preparation method thereof. The epoxy zinc-rich primer is composed of a resin system and a curing system. The mass ratio of the resin system to the curing system is 10: (2.8-3.6); the resin system comprises epoxy resin, a dispersing wetting agent, a defoaming agent, an anti-settling agent, modified zinc powder, surface metallized hollow glass beads, ferrophosphorus powder, synthetic mica and a resin diluent; the curing system comprises an epoxy resin curing agent, a curing diluent and a flash rust inhibitor. Metal zinc is plated on the surfaces of the hollow glass beads to replace part of traditional spherical zinc powder, the epoxy zinc-rich primer has the advantages of being low in density, high in activity and not prone to sedimentation, the high-solid-content super-weather-resistant epoxy zinc-rich primer with the volume solid content exceeding 80%, the salt mist resistance exceeding 5000 h and the coating film free of cracking and falling after being circulated for 180 times at the high and low temperature (-20 DEG C to 50 DEG C is prepared in cooperation with conductive graphite modified zinc powder, and the high-solid-content super-weather-resistant epoxy zinc-rich primer has the advantages of being environmentally friendly, free of pollution and the like. And the use requirements in environments with large day and night temperature difference and high corrosion are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and specifically relates to a high-solid content, super-weather-resistant epoxy zinc-rich primer and a preparation method thereof. The primer is suitable for use in environments with large day-night temperature differences and high corrosion, to improve the poor adhesion of the coating, cracking and falling off caused by dimensional deformation of the steel structure substrate due to the day-night temperature difference. The primer is particularly suitable for use in high-corrosion environments in coastal areas. Background Art

[0002] Epoxy zinc-rich primer, a commonly used heavy-duty anti-corrosion coating, is widely used for its excellent physical, mechanical, and corrosion resistance. Its anti-corrosion mechanism primarily utilizes the greater activity of elemental zinc powder than iron, achieving a sacrificial anode and providing cathodic protection for metal substrates such as steel. Furthermore, corrosion products such as zinc oxide and zinc hydroxide produced by oxidation of zinc powder can fill defects in the damaged coating and form a barrier film, promoting self-repair and preventing the intrusion of corrosive media. Studies on the anti-corrosion properties of epoxy zinc-rich primers have shown that factors such as the zinc content, zinc powder morphology, and particle size in the coating significantly influence its protective properties. The anti-corrosion effect of zinc-rich coatings primarily depends on zinc powder, making metallic zinc content an important indicator for evaluating the quality of zinc-rich coatings. Generally, higher zinc powder content results in better corrosion protection. However, high zinc powder content also brings challenges such as cost, environmental impact, and storage stability. Studies have shown that only 25% to 35% of the zinc powder in epoxy zinc-rich primers contributes to cathodic protection. Initially, the coating primarily functions as a protective layer. However, after 168 hours of immersion in a corrosive medium, some of the zinc powder is oxidized into non-conductive zinc salts, weakening the interconnectivity and conductivity of the zinc powder. This, to a certain extent, also affects the zinc powder's efficiency, and the coating's primary protective function becomes shielding. Furthermore, large temperature swings between day and night can easily cause deformation of steel substrates due to thermal expansion and contraction, which can lead to primer shedding or cracking.

[0003] Chinese patent CN 118085713 A discloses a high-solids zinc-rich primer and its preparation method. The zinc-rich primer is composed of a mixture of an aromatic polyisocyanate oligomer resin, an A / B-type water scavenger, a dispersant, a thixotropic agent, a defoamer, a flaky filler, a conductive graphene slurry, xylene, a No. 1000 solvent, an adhesion promoter, and zinc powder. By using specific resins, water scavengers, and dispersants, this patented product improves the coating's physical and mechanical properties and environmental adaptability, imparting quick-drying properties. This addresses the application limitations of traditional epoxy zinc-rich primers in low-temperature and high-humidity conditions, while also reducing VOC content to meet environmental regulations. However, the high zinc powder dosage does not address the issues of low zinc powder utilization and easy sedimentation and deactivation, resulting in poor salt spray resistance.

[0004] Chinese patent CN 114806339 A discloses a salt-spray-resistant, two-component, water-based epoxy zinc-rich primer and its preparation method. By adding glass microspheres, synthetic mica, and ferrophosphorus powder, this patent creates an effective spacer between the large amounts of zinc powder, effectively preventing moisture and corrosive ions from reaching the substrate and improving corrosion resistance. However, the zinc powder addition exceeds 60%, failing to address zinc powder sedimentation during long-term storage. Salt-spray resistance is limited to approximately 2,000 hours, and the patent also fails to address the problem of thermal expansion and contraction of steel substrates due to large temperature swings between day and night, which can lead to film shedding or cracking.

[0005] Therefore, it is particularly critical to reduce the zinc powder content while ensuring the excellent anti-corrosion performance of epoxy zinc-rich primer, improve the utilization rate of zinc powder, and improve the primer's ability to resist cold and hot deformation impact on steel substrates. This can not only expand its application range, especially in high-corrosion environments, but also improve the service life of the coating, which has important market value and research significance. Summary of the Invention

[0006] The purpose of the present invention is to address the deficiencies of traditional epoxy zinc-rich primers in terms of anti-corrosion performance, zinc powder utilization, coating adhesion and resistance to cold and hot deformation impact, and to provide a high-solid content and super-weather-resistant epoxy zinc-rich primer. By introducing surface metallized hollow glass microspheres to replace part of the traditional spherical zinc powder, the surface metallized hollow glass microspheres have the advantages of light weight, high strength, good fluidity, conductivity, heat insulation and corrosion resistance due to their special hollow thin-walled structure. When used in epoxy zinc-rich primers, the corrosion resistance and service life of the epoxy zinc-rich primer are not only improved, but also the problems of poor coating adhesion and cracking and falling off caused by temperature differences between day and night are effectively improved. The primer is particularly suitable for use in high-corrosion environments in coastal areas.

[0007] Another object of the present invention is to provide a method for preparing a high-solid-content, super-weather-resistant epoxy zinc-rich primer.

[0008] To achieve the above object, the present invention provides a high-solid content, super-weatherable epoxy zinc-rich primer composed of a resin system and a curing system, wherein the mass ratio of the resin system to the curing system is 10:(2.8-3.6);

[0009] The mass parts of each raw material in the resin system are as follows: 15-20 parts of epoxy resin, 0.5-1 parts of dispersing and wetting agent, 0.1-0.3 parts of defoaming agent, 0.1-0.5 parts of anti-settling agent, 30-50 parts of modified zinc powder, 15-30 parts of surface metallized hollow glass microspheres, 2-6 parts of ferrophosphorus powder, 2-6 parts of synthetic mica, and 8-12 parts of resin diluent.

[0010] The sum of the mass parts of the raw materials in the curing system is 100: 65-70 parts of epoxy resin curing agent, 20-30 parts of curing diluent, and 0.4-6 parts of flash rust inhibitor;

[0011] The surface metallized hollow glass microspheres have a density of 0.9 to 1.2 g / cm 3 , average particle size 10-15μm, particle size range 5-40μm, compressive strength 50-100MPa, surface metal content ≥20%;

[0012] The modified zinc powder is prepared by the following method: spherical zinc powder with a mesh size of 400-600 mesh and flaky zinc powder are selected and mixed in a mass ratio of 1:(0.5-1); conductive graphite powder with a particle size of 1-30 nm is selected and poured into an anhydrous ethanol solution, and uniformly dispersed into a nano-graphite powder slurry by an ultrasonic disperser; the mixed zinc powder is immersed in the nano-graphite powder slurry and stirred evenly, and then taken out and dried to obtain nano-graphite-coated modified zinc powder.

[0013] Preferably, the modified zinc powder is prepared by the following method: (1) selecting spherical zinc powder with a mesh size of 400-600 mesh and flaky zinc powder in a mass ratio of 1:(0.5-1) and mixing them evenly for later use; (2) selecting conductive graphite powder with a particle size of 1-30 nm and pouring it into anhydrous ethanol solution for mixing, wherein the amount of conductive graphite powder added is 1-5% of the mass of zinc powder, and the amount of anhydrous ethanol solution is (1.5-3) times the mass of zinc powder; (3) placing the above-mentioned mixed solution into an ultrasonic disperser (frequency 50HZ), adjusting the temperature to 30-40°C, ultrasonically dispersing for 15-30 minutes, and uniformly dispersing it into nano-graphite powder slurry; (4) then soaking the mixed zinc powder in the nano-graphite powder slurry and stirring it evenly, filtering it with a vacuum pump, rinsing it with clean water 3-4 times (generally 3 times), taking it out and drying it to obtain nano-graphite coated modified zinc powder.

[0014] Preferably, the defoaming agent is a silicone defoaming agent, such as BYK-066N; the dispersing wetting agent is a polyurethane and phosphate composite; the curing diluent is a mixture of benzyl alcohol, n-butanol, propylene glycol methyl ether acetate PMA and 100# solvent oil; the flash rust inhibitor is a phosphate and molybdate composite flash rust inhibitor; and the anti-settling agent is a long-chain alkyl silane.

[0015] Preferably, the surface metallized hollow glass microspheres are made by the following process:

[0016] 1) Select density 0.6~0.7g / cm 3 Hollow glass microspheres with a compressive strength of ≥55 MPa are separated into products with an average particle size of 10-15 μm by air classification equipment, and then sieved through a 400-mesh sieve to obtain products with a density of 0.7-0.9 g / cm3 Hollow glass microsphere product A with a compressive strength of 70-130 MPa, an average particle size of 10-15 μm, and a particle size range of 5-40 μm;

[0017] 2) Place the hollow glass microsphere product A in a sodium hydroxide solution with a concentration of 2-10%, control the water bath temperature at 30-60°C, stir at a speed of 100-800 r / min, and perform alkaline washing for 1-6 hours. After the alkaline washing is completed, take it out and rinse it with 5% glacial acetic acid solution. The number of rinses is generally 2-3 times (usually 2 times), then rinse with water and dry it to obtain a density of 0.65-0.8 g / cm 3 , compressive strength 50 ~ 100MPa, average particle size 10 ~ 15μm, particle size range 5 ~ 40μm surface rich in hydroxyl hollow glass microsphere intermediate B; the hollow glass microsphere product A and sodium hydroxide solution according to the mass ratio of 1: (90 ~ 110) is appropriate, the best is 1: 100;

[0018] 3) placing the hollow glass microsphere intermediate B into an activation solution, sealing and activating for 20 to 40 minutes at an activation temperature of 50 to 80° C., and then drying at 50° C. to obtain an activated powder C;

[0019] 4) First, heat the galvanizing solution to 50-90°C, then pour the activated powder C into the galvanizing solution, add 1g activated powder C: (50-400ml) galvanizing solution, and stir mechanically at a speed of 400-1000r / min until the reaction is completed. Take it out and rinse it with water 3-5 times, and dry it at 50°C to obtain a uniform surface coating, fine galvanized particles, and a density of 0.9-1.2g / cm 3 , average particle size 10-15μm, particle size range 5-40μm, compressive strength 50-100MPa, surface metallized hollow glass microspheres with surface metal content ≥20%.

[0020] Preferably, in step 2), the hollow glass microsphere product A is placed in a sodium hydroxide solution with a concentration of 4-6%, the water bath temperature is controlled at 45-55°C, the stirring speed is 300-500 r / min, and the alkali washing time is 2-4 hours. After the alkali washing is completed, it is taken out and rinsed with 5% glacial acetic acid solution, then rinsed with water and dried to obtain a hollow glass microsphere intermediate B with a surface rich in hydroxyl groups.

[0021] Preferably, in step 3), the activation solution is prepared according to the following process: alcohol: water is prepared at a mass ratio of 1: (8-10) to prepare a solvent, and then PdCl is uniformly dispersed in the solvent at a mass ratio of PdCl: solvent of 1: (9000-15000) to prepare the activation solution.

[0022] Preferably, in step 4), the zinc plating solution is prepared by the following method: water, zinc salt, sodium citrate, sodium hypophosphite, potassium sodium tartrate, boric acid, and ethylene glycol are sequentially added in a mass ratio of 40:1:2.4:1:0.3:2:0.2 and stirred evenly to obtain the zinc plating solution required for the surface metallized hollow glass microspheres.

[0023] Preferably, the zinc salt is one or more of zinc sulfate, zinc chloride, zinc carbonate, zinc nitrate and zinc dihydrogen phosphate.

[0024] Preferably, the mesh size of the ferrophosphorus powder is 800-1500 mesh; the mesh size of the synthetic mica is 800-1250 mesh.

[0025] The present invention also discloses a method for preparing a high-solid-content, super-weather-resistant epoxy zinc-rich primer, comprising the following preparation steps:

[0026] 1) Epoxy resin, dispersing wetting agent, modified zinc powder, ferrophosphorus powder, synthetic mica, and resin diluent are first prepared in proportion and dispersed and mixed at a high speed of 1500-2000 r / min; when the speed is reduced to 500-1000 r / min, surface metallized hollow glass microspheres are added, and after stirring for 10-30 minutes, the speed is further reduced to 300-600 r / min, a defoaming agent is added, and stirring is carried out for 30-60 minutes; after bubbles are completely eliminated, an anti-settling agent is added and stirred for 40-90 minutes to prepare a resin system;

[0027] 2) uniformly mixing the epoxy curing agent, curing diluent and flash rust inhibitor in proportion to prepare a curing system;

[0028] 3) When used, the resin system prepared by the above method and the curing system are mixed in proportion to obtain a high-solid content, super-weather-resistant epoxy zinc-rich primer with a volume solid content of more than 80%, salt spray resistance of more than 5000 hours, and no cracking or shedding of the coating film after 180 cycles at high and low temperatures of -20 to 50°C.

[0029] Compared with the prior art, the high-solid-content, super-weather-resistant epoxy zinc-rich primer and its preparation method of the present invention have the following beneficial effects:

[0030] (1) The prepared surface metallized hollow glass microspheres have a density close to that of resin and are not easy to float or settle. They have good fluidity and are easy to disperse. They have strong electrical conductivity and high surface metal activity. Due to their special hollow structure, they have lower density and thermal conductivity than traditional zinc powder.

[0031] (2) The present invention introduces surface metallized hollow glass microspheres with low density, high activity, good fluidity and special hollow structure to replace part of the traditional spherical zinc powder with high density and easy sedimentation and agglomeration, thereby greatly reducing the amount of zinc powder used and improving the volume solid content of the zinc-rich primer, solving the problem of low utilization rate and reduced anti-corrosion performance of traditional epoxy zinc-rich primers caused by zinc powder agglomeration and sedimentation. In addition, due to its low thermal conductivity, the coating has better thermal insulation performance, can well resist the expansion and contraction caused by heating and cooling of the steel substrate, effectively prevent heat conduction, improve the primer's ability to resist the impact of hot and cold deformation on the steel substrate, and will not cause the coating to fall off or crack due to temperature changes between day and night, thereby greatly improving the service life of the coating.

[0032] (3) Although flaky zinc powder has stronger hiding power, floating power, shielding power and metallic luster than spherical zinc powder, it is difficult to add a large amount of flaky zinc powder to the primer to prepare a high-solid primer due to its strong thixotropy and obvious thickening. The present invention introduces a small amount of flaky zinc powder and uses it in combination with spherical zinc powder, which not only improves the surface brightness and metallic texture of the coating, but also enhances the adhesion, low porosity and low permeability of the coating. At the same time, it adopts conductive graphite coating modification to improve its conductivity, greatly improve the activity and utilization rate of zinc powder, and enhance the corrosion resistance of the zinc-rich primer, making its salt spray resistance exceed 5000h.

[0033] (4) The present invention coats the surface of hollow glass microspheres with metallic zinc to replace part of the traditional spherical zinc powder, thereby preparing a high-solid content, super-weather-resistant epoxy zinc-rich primer with the advantages of low density, high activity, and low sedimentation resistance, and combining it with conductive graphite-modified zinc powder to prepare a high-solid content, super-weather-resistant epoxy zinc-rich primer with a volume solid content of more than 80%, salt spray resistance of more than 5000 hours, and 180 cycles of high and low temperature (-20 to 50°C) without cracking or shedding. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Scanning electron microscope images of the surface metallization of the surface metallized hollow glass microspheres prepared in Examples 1 and 3 of the present invention;

[0035] Figure 2 This is a scanning electron microscope image of the surface metallization of the surface metallized hollow glass microspheres prepared in Example 2 of the present invention;

[0036] Figure 3 This is a scanning electron microscope image of the surface metallization of the hollow glass microspheres without surface metallization treatment in comparative example 3 of the present invention. DETAILED DESCRIPTION

[0037] To illustrate the present invention, a high-solid-content, super-weather-resistant epoxy zinc-rich primer and its preparation method are further described in detail below with reference to the examples. However, the present invention is not limited to the examples.

[0038] Example 1

[0039] In this embodiment, a high-solid content, super-weatherable epoxy zinc-rich primer and a preparation method thereof are provided. The high-solid content, super-weatherable epoxy zinc-rich primer is composed of a resin system and a curing system. The mass fractions of the raw materials in the resin system are as follows: 20 parts of epoxy resin, 0.7 parts of a dispersing and wetting agent, 0.3 parts of a defoaming agent, 0.3 parts of a long-chain alkyl silane, 40 parts of modified zinc powder, 20 parts of surface-metallized hollow glass microspheres, 5 parts of ferrophosphorus powder, 4 parts of synthetic mica, and 9.7 parts of a resin diluent.

[0040] The preparation method of the resin system of this embodiment is:

[0041] (1) Select spherical and flaky zinc powders with a mesh size of 500 mesh and mix them evenly in a mass ratio of 1:0.5 for later use; weigh conductive graphite powder with a particle size of 5 nm at a ratio of 3% of the weight of the zinc powder, and pour it into an anhydrous ethanol solution with a weight ratio of 1:2 of the weight of the zinc powder; put the above mixed solution into an ultrasonic disperser, adjust the temperature to 35°C, and use ultrasonic waves at a frequency of 50 Hz for 30 minutes to uniformly disperse the conductive graphite into a slurry; then soak the mixed zinc powder in the nano-graphite powder slurry and stir for 5 minutes, filter it with a vacuum pump, rinse it with clean water three times, take it out and put it into a vacuum drying oven at 50°C to dry it, and then sieve it with an 80-mesh screen to obtain nano-graphite coated modified zinc powder for later use.

[0042] (2) Select density 0.64g / cm 3 Hollow glass microspheres with a compressive strength of 65 MPa were separated into products with an average particle size of 14 μm through an airflow classification device, and then sieved through a 400-mesh sieve to obtain a product with a density of 0.75 g / cm 3 , compressive strength 89MPa, average particle size 14μm, particle size range 6 ~ 39μm hollow glass microsphere products. The prepared hollow glass microspheres: sodium hydroxide solution according to the mass ratio of 1:100, put into the concentration of 5% sodium hydroxide solution, the water bath temperature is controlled at 50 ℃, the stirring speed is 400r / min, the alkali washing time is 4h, after the alkali washing is completed, take out and rinse with 5% glacial acetic acid solution twice, then rinse with clean water and dry, the density is 0.70g / cm 3Hollow glass microsphere intermediates with a hydroxyl-rich surface, a compressive strength of 82 MPa, an average particle size of 14 μm, and a particle size range of 6 to 39 μm. An activation solution is prepared by preparing a solvent with an alcohol:water ratio of 1:9 by mass. PdCl is then evenly dispersed in the solvent at a PdCl:solvent ratio of 1:10,000 by mass. The intermediate and activation solution are placed in the activation solution at a ratio of 1:100 by mass. The mixture is sealed and activated for 30 minutes at 60°C. The activated powder is then removed and dried at 50°C to obtain the activated powder. Water, zinc sulfate, sodium citrate, sodium hypophosphite, potassium sodium tartrate, boric acid, and ethylene glycol were added in a mass ratio of 40:1:2.4:1:0.3:2:0.2 in sequence and stirred evenly. The mixture was heated to 70°C. The activated powder and plating solution were added at a ratio of 1g:200ml of zinc plating solution. The mechanical stirring speed was 500r / min. The mixture was stirred until the reaction was completed and no obvious bubbles were generated. The mixture was filtered, rinsed with water 3 times, and dried in a vacuum drying oven at 50°C. The surface was uniformly plated, the zinc-plated particles were fine, and the density was 0.964g / cm 3 Surface metallized hollow glass microspheres with an average particle size of 14 μm, a particle size range of 6 to 39 μm, a compressive strength of 83 MPa, and a surface metal content of 30.4% are available for use.

[0043] (3) adding epoxy resin, dispersing wetting agent, modified zinc powder, ferrophosphorus powder, synthetic mica, and resin diluent in accordance with the formula ratio, and using a high-speed disperser to select a speed of 1500 r / min for high-speed dispersion and mixing for 15 minutes; reducing the speed to 800 r / min, adding surface metallized hollow glass microspheres, stirring for 30 minutes, and further reducing the speed to 400 r / min, adding a defoamer, and stirring for 45 minutes; after the bubbles are completely eliminated, adding an anti-settling agent, long-chain alkyl silane, and stirring for 60 minutes to obtain a resin system;

[0044] The preparation method of the curing system in this embodiment is:

[0045] A polyamide epoxy curing agent, a curing diluent, and a flash rust inhibitor were added in a mass ratio of 67:30:3, and stirred at a low speed of 200 r / min for 15 minutes to prepare a curing system;

[0046] The curing system prepared by the above method is added to the resin system at a mass ratio of 3.3:10, and the stirring speed of the high-speed disperser is 400r / min. The desired epoxy zinc-rich primer can be obtained by stirring and mixing evenly.

[0047] Example 2

[0048] In this embodiment, a high-solid content, super-weatherable epoxy zinc-rich primer and a preparation method thereof are provided. The high-solid content, super-weatherable epoxy zinc-rich primer is composed of a resin system and a curing system. The mass fractions of the raw materials in the resin system are as follows: 20 parts of epoxy resin, 0.7 parts of a dispersing and wetting agent, 0.3 parts of a defoaming agent, 0.5 parts of a long-chain alkyl silane, 33 parts of modified zinc powder, 30 parts of surface-metallized hollow glass microspheres, 2 parts of ferrophosphorus powder, 2 parts of synthetic mica, and 11.5 parts of a resin diluent.

[0049] The preparation method of the resin system of this embodiment is:

[0050] (1) Select spherical and flaky zinc powders with a mesh size of 500 mesh and mix them evenly in a mass ratio of 1:0.5 for later use; weigh conductive graphite powder with a particle size of 5 nm at a ratio of 5% by mass of the zinc powder, and pour it into an anhydrous ethanol solution with a ratio of 1:2 by mass of the zinc powder; put the above mixed solution into an ultrasonic disperser, adjust the temperature to 35°C, and use ultrasonic waves at a frequency of 50 Hz for 30 minutes to uniformly disperse the conductive graphite into a slurry; then soak the mixed zinc powder in the nano-graphite powder slurry and stir for 5 minutes, filter it with a vacuum pump, rinse it with clean water three times, take it out and put it into a vacuum drying oven at 50°C to dry it, and then sieve it with an 80-mesh screen to obtain nano-graphite coated modified zinc powder for later use.

[0051] (2) Select density 0.64g / cm 3 Hollow glass microspheres with a compressive strength of 65 MPa were separated into products with an average particle size of 14 μm through an airflow classification device, and then sieved through a 400-mesh sieve to obtain a product with a density of 0.75 g / cm 3 , compressive strength 89MPa, average particle size 14μm, particle size range 6 ~ 39μm hollow glass microsphere products. The prepared hollow glass microspheres: sodium hydroxide solution according to the mass ratio of 1:100, put into the concentration of 2% sodium hydroxide solution, the water bath temperature is controlled at 50 ℃, the stirring speed is 400r / min, the alkali washing time is 2h, after the alkali washing is completed, take out and rinse with 5% glacial acetic acid solution twice, then rinse with clean water and dry, the obtained density is 0.72g / cm 3Hollow glass microsphere intermediates with a hydroxyl-rich surface, a compressive strength of 84 MPa, an average particle size of 14 μm, and a particle size range of 6 to 39 μm. An activation solution is prepared by preparing a solvent with an alcohol:water ratio of 1:9 by mass. PdCl is then evenly dispersed in the solvent at a PdCl:solvent ratio of 1:10,000 by mass. The intermediate is then placed in the activation solution at a ratio of 1:200 by mass. The mixture is sealed and activated for 30 minutes at 60°C. The activated powder is then dried at 50°C to obtain the activated powder. Water, zinc sulfate, sodium citrate, sodium hypophosphite, potassium sodium tartrate, boric acid, and ethylene glycol were added in a mass ratio of 40:1:2.4:1:0.3:2:0.2 in sequence and stirred evenly. The mixture was heated to 70°C. The activated powder and plating solution were added at a ratio of 1g:400ml of zinc plating solution. The mechanical stirring speed was 500r / min. The mixture was stirred until the reaction was completed and no obvious bubbles were generated. The mixture was filtered, rinsed with water 3 times, and dried in a vacuum drying oven at 50°C to obtain a density of 1.09g / cm 3 Surface metallized hollow glass microspheres with an average particle size of 14 μm, a particle size range of 6 to 39 μm, a compressive strength of 85 MPa, and a surface metal content of 38.1% are available for use.

[0052] (3) adding epoxy resin, dispersing wetting agent, modified zinc powder, ferrophosphorus powder, synthetic mica, and resin diluent in accordance with the formula ratio, and using a high-speed disperser to select a speed of 1500 r / min for high-speed dispersion and mixing for 15 minutes; reducing the speed to 800 r / min, adding surface metallized hollow glass microspheres, stirring for 30 minutes, and further reducing the speed to 400 r / min, adding a defoamer, and stirring for 45 minutes; after the bubbles are completely eliminated, adding an anti-settling agent, long-chain alkyl silane, and stirring for 60 minutes to obtain a resin system;

[0053] The preparation method of the curing system in this embodiment is:

[0054] A polyamide epoxy curing agent, a curing diluent, and a flash rust inhibitor were added in a mass ratio of 65:30:5, and stirred at a low speed of 200 r / min for 15 minutes to prepare a curing system;

[0055] The curing system prepared by the above method is added to the resin system at a mass ratio of 3.3:10, and a high-speed disperser is stirred at a speed of 400r / min. The desired epoxy zinc-rich primer can be obtained by stirring and mixing evenly.

[0056] Example 3

[0057] The difference between Example 3 and Example 2 is that the surface metallization treatment of the hollow glass microspheres is prepared according to the method of Example 1, and the rest is the same as Example 2.

[0058] Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 1 is that all the selected zinc powders are 500-mesh spherical zinc powders, and the rest are the same as Example 1.

[0060] Comparative Example 2

[0061] The difference between Comparative Example 2 and Example 1 is that the selected zinc powder is not modified with the conductive graphite powder, and the other aspects are the same as Example 1.

[0062] Comparative Example 3

[0063] The difference between Comparative Example 3 and Example 1 is that the selected hollow glass microspheres are not subjected to surface metallization treatment and are directly added to the resin system after airflow sorting. Other steps are the same as in Example 1.

[0064] Comparative Example 4

[0065] The difference between Comparative Example 4 and Example 1 is that the modified zinc powder is replaced with ordinary spherical zinc powder, and the surface metallized hollow glass microspheres are not added.

[0066] In Comparative Example 4, the zinc-rich primer consists of a resin system and a curing system; the mass parts of the raw materials in the resin system are as follows: 15 parts of epoxy resin, 0.7 parts of dispersing and wetting agent, 0.6 parts of defoaming agent, 0.7 parts of long-chain alkyl silane, 70 parts of zinc powder, 4 parts of ferrophosphorus powder, 4 parts of synthetic mica, and 5 parts of resin diluent;

[0067] The resin system in Comparative Example 4 was prepared by sequentially adding epoxy resin, a dispersing wetting agent, 500-mesh spherical zinc powder, ferrophosphorus powder, synthetic mica, and a resin diluent according to the formula ratio, and dispersing and mixing them at a high speed of 1500 r / min using a high-speed disperser for 15 minutes; reducing the speed to 400 r / min, adding a defoaming agent, and stirring for 45 minutes; after the bubbles were completely eliminated, adding an anti-settling agent, a long-chain alkyl silane, and stirring for 60 minutes to prepare a resin system;

[0068] The preparation method of the curing system in Comparative Example 4 is as follows: polyamide epoxy curing agent, curing diluent and flash rust inhibitor are added in a mass ratio of 67:30:3, and stirred at a low speed of 200 r / min for 15 minutes to prepare a curing system;

[0069] The curing system prepared by the above method and the resin system are added into the resin system at a mass ratio of 3.5:10, with a high-speed disperser stirring speed of 400r / min, while stirring, and mixed evenly to obtain the required epoxy zinc-rich primer.

[0070] The performance tests are as follows.

[0071] The epoxy zinc-rich primers of each example and comparative example were applied to tinplate substrates, labeled Examples 1-3 and Comparative Examples 1-4, and their adhesion, salt spray resistance, impact resistance, and thick film crack resistance were tested in accordance with national standards GB / T5210-2006, GB / T 1771-2007, GB / T 1732-2020, and JG / T 25-2017. Other properties were tested in accordance with relevant standards, and the test results are shown in Table 1.

[0072] Table 1 Performance test results of examples and comparative examples

[0073]

[0074]

[0075] Figure 1 As shown in the scanning electron microscope images of the surface metallization of the surface metallized hollow glass microspheres prepared in Examples 1 and 3 of the present invention, it can be seen that by plating the surface of the hollow glass microspheres with metallic zinc by the chemical metal plating method adopted by the present invention, surface metallized hollow glass microspheres with uniform plating and dense coating can be obtained.

[0076] Depend on Figure 2 As shown in the scanning electron microscope image of the surface metallization of the surface metallized hollow glass microspheres prepared in Example 2 of the present invention, it can be seen that the sodium hydroxide concentration is low, the treatment time is short, and the hydroxyl content on the surface of the hollow glass microspheres is low, resulting in poor adhesion of the subsequent chemically plated zinc metal layer and easy detachment of the coating.

[0077] Depend on Figure 3 As shown in the scanning electron microscope image of the surface metallization of the hollow glass microspheres without surface metallization treatment in Comparative Example 3 of the present invention, it can be seen that the surface of the product without surface metallization treatment is smooth under the scanning electron microscope without a large number of protrusions or other substances attached.

[0078] in conclusion:

[0079] The test data results of the embodiments show that the epoxy zinc-rich primer prepared by the method of the present invention not only retains the characteristics of corrosion resistance and high adhesion, but also has the characteristics of high volume solid content, good coating cracking resistance, prevention of zinc powder sedimentation, and high zinc powder activity. It can greatly improve the corrosion resistance and service life of the epoxy zinc-rich primer, and improve the shortcomings of poor coating adhesion, cracking and falling off caused by dimensional deformation of the steel structure substrate due to the temperature difference between day and night, and meet the use requirements in environments with large temperature difference between day and night and high corrosion.

[0080] The test data from Example 1 and Comparative Example 1 show that the partially flaky zinc powder introduced in the present invention not only enhances the anti-settling effect of the primer but also significantly improves the primer's salt spray resistance. The test data from Example 1 and Comparative Example 2 show that the present invention significantly improves the zinc powder's efficiency and utilization by coating it with conductive graphite powder, resulting in excellent salt spray resistance.

[0081] From the test results of Examples 1-3 and Comparative Example 3, it can be seen that the more uniform the surface coating of the surface metallized galvanized hollow glass microspheres prepared by the present invention, the more complete the coating, the denser and finer the coating, the higher its conductivity, the higher the activity of the surface zinc powder, and the more beneficial it is to the salt spray resistance of the zinc-rich primer. The hollow glass microspheres that have not been surface metallized have no obvious effect on improving the activity of zinc powder, reducing the amount of zinc powder used, and improving the salt spray resistance of the zinc-rich primer.

[0082] It can be seen from the test results of Examples 1-3 and Comparative Example 4 that the present invention significantly reduces the amount of zinc powder and the thermal conductivity of the primer by introducing surface metallized hollow glass microspheres, improves the volume solid content and salt spray resistance of the primer, and enhances the storage stability, coating crack resistance, and resistance to cold and hot deformation shock of the primer.

[0083] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0084] The above description is merely an embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A high-solid, super-weather-resistant epoxy zinc-rich primer, characterized by: It consists of a resin system and a curing system, wherein the mass ratio of the resin system to the curing system is 10:(2.8-3.6); The mass parts of each raw material in the resin system are as follows: 15-20 parts of epoxy resin, 0.5-1 parts of dispersing and wetting agent, 0.1-0.3 parts of defoaming agent, 0.1-0.5 parts of anti-settling agent, 30-50 parts of modified zinc powder, 15-30 parts of surface metallized hollow glass microspheres, 2-6 parts of ferrophosphorus powder, 2-6 parts of synthetic mica, and 8-12 parts of resin diluent. The sum of the mass parts of the raw materials in the curing system is 100: 65-70 parts of epoxy resin curing agent, 20-30 parts of curing diluent, and 0.4-6 parts of flash rust inhibitor; The surface metallized hollow glass microspheres have a density of 0.9 to 1.2 g / cm 3 , average particle size 10-15μm, particle size range 5-40μm, compressive strength 50-100MPa, surface metal content ≥25%; The modified zinc powder is prepared by the following method: spherical zinc powder with a mesh size of 400-600 mesh and flaky zinc powder are selected and mixed in a mass ratio of 1:(0.5-1); conductive graphite powder with a particle size of 1-30 nm is selected and poured into an anhydrous ethanol solution, and uniformly dispersed into a nano-graphite powder slurry by an ultrasonic disperser; the mixed zinc powder is immersed in the nano-graphite powder slurry and stirred evenly, and then taken out and dried to obtain nano-graphite-coated modified zinc powder.

2. The high-solid, super-weather-resistant epoxy zinc-rich primer according to claim 1, characterized in that: The defoaming agent is a silicone defoaming agent; the dispersing wetting agent is a polyurethane and phosphate composite; the curing diluent is a mixture of benzyl alcohol, n-butanol, propylene glycol methyl ether acetate PMA and 100# solvent oil; the flash rust inhibitor is a phosphate and molybdate composite flash rust inhibitor; and the anti-settling agent is a long-chain alkyl silane.

3. A high-solid content, super-weather-resistant epoxy zinc-rich primer as claimed in claim 1, characterized in that The surface metallized hollow glass microspheres are made by the following process: 1) Select density 0.6~0.7g / cm 3 Hollow glass microspheres with a compressive strength of ≥55 MPa are separated into products with an average particle size of 10-15 μm by air classification equipment, and then sieved through a 400-mesh sieve to obtain products with a density of 0.7-0.9 g / cm 3 Hollow glass microsphere product A with a compressive strength of 70-130 MPa, an average particle size of 10-15 μm, and a particle size range of 5-40 μm; 2) Place the hollow glass microsphere product A in a sodium hydroxide solution with a concentration of 2-10%, control the water bath temperature at 30-60°C, stir at a speed of 100-800 r / min, and perform alkaline washing for 1-6 hours. After the alkaline washing is completed, take out the product and rinse it with 5% glacial acetic acid solution, then rinse it with water and dry it to obtain a density of 0.65-0.8 g / cm 3 , compressive strength 50 ~ 100MPa, average particle size 10 ~ 15μm, particle size range 5 ~ 40μm surface rich in hydroxyl hollow glass microsphere intermediate B; 3) placing the hollow glass microsphere intermediate B into an activation solution, sealing and activating for 20 to 40 minutes at an activation temperature of 50 to 80° C., and then drying at 50° C. to obtain an activated powder C; 4) First, heat the galvanizing solution to 50-90°C, then pour the activated powder C into the galvanizing solution, add 1g activated powder C: (50-400ml) galvanizing solution, and stir mechanically at a speed of 400-1000r / min until the reaction is completed. Take it out and rinse it with water 3-5 times, and dry it at 50°C to obtain a uniform surface coating, fine galvanized particles, and a density of 0.9-1.2g / cm 3 , average particle size 10-15μm, particle size range 5-40μm, compressive strength 50-100MPa, surface metallized hollow glass microspheres with surface metal content ≥20%.

4. A high-solid, super-weather-resistant epoxy zinc-rich primer as claimed in claim 3, characterized in that: In step 2), the hollow glass microsphere product A is placed in a sodium hydroxide solution with a concentration of 4 to 6%, the water bath temperature is controlled at 45 to 55° C., the stirring speed is 300 to 500 r / min, and the alkali washing time is 2 to 4 hours. After the alkali washing is completed, the hollow glass microsphere product A is taken out and rinsed with a 5% glacial acetic acid solution, then rinsed with water and dried to obtain a hollow glass microsphere intermediate B with a surface rich in hydroxyl groups; the hollow glass microsphere product A and the sodium hydroxide solution are in a mass ratio of 1:

100.

5. A high-solid, super-weather-resistant epoxy zinc-rich primer as claimed in claim 3, characterized in that In step 3), the activation solution is prepared according to the following process: alcohol: water is prepared at a mass ratio of 1: (8-10) to prepare a solvent, and then PdCl is uniformly dispersed in the solvent at a mass ratio of PdCl: solvent of 1: (9000-15000) to prepare the activation solution.

6. A high-solid, super-weather-resistant epoxy zinc-rich primer as claimed in claim 3, characterized in that In step 4), the zinc plating solution is prepared by the following method: water, zinc salt, sodium citrate, sodium hypophosphite, potassium sodium tartrate, boric acid, and ethylene glycol are added in a mass ratio of 40:1:2.4:1:0.3:2:0.2 and stirred in sequence to obtain the zinc plating solution required for the surface metallized hollow glass microspheres.

7. The high-solid, super-weather-resistant epoxy zinc-rich primer according to claim 6, characterized in that: The zinc salt is one or more of zinc sulfate, zinc chloride, zinc carbonate, zinc nitrate and zinc dihydrogen phosphate.

8. The high-solid, super-weather-resistant epoxy zinc-rich primer according to claim 1, characterized in that: The mesh size of the ferrophosphorus powder is 800-1500 meshes; the mesh size of the synthetic mica is 800-1250 meshes.

9. A high-solid, super-weather-resistant epoxy zinc-rich primer as claimed in claim 1, characterized in that The modified zinc powder is prepared by the following method: (1) Select spherical zinc powder with a mesh size of 400-600 mesh and flaky zinc powder in a mass ratio of 1: (0.5-1) and mix them evenly for later use; (2) Selecting conductive graphite powder with a particle size of 1 to 30 nm and pouring it into anhydrous ethanol solution for mixing, the amount of conductive graphite powder added is 1 to 5% of the mass of zinc powder, and the amount of anhydrous ethanol solution is (1.5 to 3) times the mass of zinc powder; (3) placing the above mixed solution into an ultrasonic disperser, adjusting the temperature to 30-40°C, and ultrasonically dispersing for 15-30 minutes to uniformly disperse into a nano-graphite powder slurry; (4) The mixed zinc powder is then immersed in the nano-graphite powder slurry and stirred evenly, filtered with a vacuum pump, rinsed with clean water 3 to 4 times, taken out and dried to obtain nano-graphite coated modified zinc powder.

10. The method for preparing a high-solid-content, super-weather-resistant epoxy zinc-rich primer as described in claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, characterized in that The method comprises the following preparation steps: 1) Epoxy resin, dispersing wetting agent, modified zinc powder, ferrophosphorus powder, synthetic mica, and resin diluent are first prepared in proportion and dispersed and mixed at a high speed of 1500-2000 r / min; when the speed is reduced to 500-1000 r / min, surface metallized hollow glass microspheres are added, and after stirring for 10-30 minutes, the speed is further reduced to 300-600 r / min, a defoaming agent is added, and stirring is carried out for 30-60 minutes; after bubbles are completely eliminated, an anti-settling agent is added and stirred for 40-90 minutes to prepare a resin system; 2) uniformly mixing the epoxy curing agent, curing diluent and flash rust inhibitor in proportion to prepare a curing system; 3) When used, the resin system prepared by the above method and the curing system are mixed in proportion to obtain a high-solid content, super-weather-resistant epoxy zinc-rich primer with a volume solid content of more than 80%, salt spray resistance of more than 5000 hours, and no cracking or shedding of the coating film after 180 cycles at high and low temperatures of -20 to 50°C.

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