Phosphorus-free salt-fog-resistant 1000h environmental protection epoxy coating and preparation method thereof

Abstract

This application relates to the field of coating compositions, specifically disclosing an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 hours and its preparation method, comprising component A and component B, including the following raw materials in parts by weight: epoxy resin 35-40 parts, n-butanol 2-2.5 parts, xylene 5-5.5 parts, dispersant 0.1-0.5 parts, iron oxide red 10-12 parts, heavy calcium carbonate 4-6 parts, zinc oxide 2-4 parts, rust-inhibiting silica powder 4-6 parts, kaolin 4-6 parts, talc powder 3-4 parts, rust-inhibiting pigment 7-8 parts, precipitated barium sulfate 12-15 parts, petroleum resin 4-5 parts, leveling agent 0.02-0.06 parts; curing agent 12-15 parts, n-butanol 1-2 parts, xylene 1-1.5 parts, dispersant 1-3 parts, mica iron oxide 0.4-0.6 parts; talc powder including one or more of calcium ion exchange talc powder, cerium ion exchange talc powder, and lanthanum ion exchange talc powder. The coating in this application is environmentally friendly, phosphorus-free, and has good salt spray resistance.

Description

Technical Field

[0001] This application relates to the field of coating compositions, and more specifically, to an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 hours and a method for preparing the same. Background Technology

[0002] In modern industry, especially in engineering machinery manufacturing, protective coatings play a crucial role in the long-term performance and durability of equipment. Epoxy primers, as a common protective coating, have numerous advantages. With the continuous development of the engineering machinery industry, the requirements for coatings are increasingly stringent. Traditional primers, when facing complex working environments and harsh climatic conditions, such as rust-preventive primers for offshore wind power platforms, large ships, and port equipment, need to have higher salt spray resistance, higher adhesion, and higher environmental protection requirements. However, existing rust-preventive primers typically rely on the addition of phosphorus-based raw materials such as aluminum tripolyphosphate, zinc phosphate, and iron phosphate powder to form a passivation layer for rust prevention. This fails to meet environmental requirements, leading to eutrophication of water bodies. Furthermore, insufficient film density allows chloride ions to easily penetrate and cause electrochemical corrosion. Rust-preventive pigments, such as zinc phosphate, have poor interfacial bonding with the resin, easily forming pores that are prone to blistering or peeling in salt spray environments, resulting in protective failure. For these reasons, rust-preventive coatings cannot effectively resist salt spray corrosion, typically failing salt spray tests for less than 500 hours.

[0003] There is a need to find alternative raw material solutions to meet the needs of construction machinery under various extreme conditions. Developing a phosphorus-free, highly efficient, salt spray-resistant, and high-performance epoxy anti-rust primer is an inevitable trend. Summary of the Invention

[0004] To ensure that the epoxy primer is phosphorus-free and has stable salt spray resistance for more than 1000 hours, this application provides an environmentally friendly epoxy coating that is phosphorus-free and has salt spray resistance for 1000 hours, and its preparation method.

[0005] In one aspect, this application provides an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 hours, comprising component A and component B;

[0006] Component A comprises the following raw materials in parts by weight: 35-40 parts epoxy resin, 2-2.5 parts n-butanol, 5-5.5 parts xylene, 0.1-0.5 parts dispersant, 10-12 parts iron oxide red, 4-6 parts heavy calcium carbonate, 2-4 parts zinc oxide, 4-6 parts rust-inhibiting silica powder, 4-6 parts kaolin, 3-4 parts talc, 7-8 parts ST rust-inhibiting pigment, 12-15 parts precipitated barium sulfate, 4-5 parts petroleum resin, and 0.02-0.06 parts leveling agent;

[0007] Component B comprises the following raw materials in parts by weight: 12-15 parts curing agent, 1-2 parts n-butanol, 1-1.5 parts xylene, 1-3 parts dispersant, and 0.4-0.6 parts mica iron oxide;

[0008] The talc powder includes one or more of calcium ion-exchange talc powder, cerium ion-exchange talc powder, and lanthanum ion-exchange talc powder.

[0009] By employing the above scheme, using epoxy resin as the matrix component, and adding iron oxide red and rust-inhibiting silica powder, the porosity of the coating is reduced, and the penetration of salt spray media is slowed down. Precipitated barium sulfate has high chemical inertness, reducing coating shrinkage and preventing cracking. Talc powder has a certain layered structure, extending the diffusion path of salt spray media. The combined effect of these factors provides physical rust prevention. By limiting the talc powder to include calcium ion exchange talc powder, cerium ion exchange talc powder, and lanthanum ion exchange talc powder, the introduction of calcium ions reduces the surface polarity of talc powder, enhancing its compatibility with epoxy resin. Simultaneously, the alkalinity of calcium helps neutralize acidic corrosive media, improving salt spray resistance. It can also react with strontium chromium yellow to form stable compounds such as CaCrO4, inhibiting electrochemical corrosion. Meanwhile, Ce... 3+ It has high redox activity and neutralizes Cl. - And form a stable CeO2 passivation film to inhibit corrosion of the metal substrate, La 3+ With Cl - The formation of LaCl3 precipitate reduces the concentration of free Cl-, while simultaneously stabilizing the coating interface through coordination, and Ce... 3+ and La 3+ With higher charge density and ionic radius, the modified talc forms a denser interlayer structure, and when used in conjunction with calcium ion talc, it further enhances the labyrinth effect.

[0010] By adding a certain amount of petroleum resin to balance hardness and flexibility, salt spray resistance failure caused by internal stress is reduced. Adding a certain amount of strontium chrome yellow and rust-inhibiting pigments provides dual protection by covering both the anode and cathode, isolating corrosive media while repairing damaged areas through dissolution and reprecipitation, resulting in more stable coating performance. Rust-inhibiting silicate powder generates silicate ions under salt spray conditions. These silicate ions combine with iron ions generated by anodic ionization and calcium ions from the rust-inhibiting pigment surface and coating to form Fe2(SiO3)3 and CaSiO3. These two silicates are insoluble and chemically stable. They migrate to the metal surface to form a passivation layer, preventing further electrochemical reactions and providing long-term effective protection against corrosion. By using n-butanol and xylene together to adjust the coating viscosity and evaporation rate, a coating with more uniform tension, higher surface smoothness, and less susceptibility to cracking and blistering is obtained. By adding a certain amount of n-butanol and xylene to component B, the dispersion in the coating system is more uniform and the curing is more complete. By adding a certain amount of mica iron oxide, the lamellar structure further extends the penetration path of salt spray and further reduces the shrinkage of the coating, thus extending the stability of salt spray resistance.

[0011] In one specific implementation, the talc powder includes calcium ion-exchange talc powder, cerium ion-exchange talc powder and lanthanum ion-exchange talc powder, in a mass ratio of 1:(1.5-2.5):(2-2.1).

[0012] By adopting the above scheme, the mass ratio of the three ion-exchange talc powders is limited. This may be because the talc powders prepared by ions with different charge densities and ionic radii have different degrees of density, the tension in the system is relatively uniform and it is not easy to produce gaps. When used together, the labyrinth effect is more significant. At the same time, ions with different redox activities form a passivation film with chloride ions in turn, which further delays the corrosion process.

[0013] In one specific implementation, the talc is chemically etched talc, and the etching steps include: adding talc to a mixture of hydrofluoric acid and hydrochloric acid, stirring, filtering, washing, and drying to obtain chemically etched talc.

[0014] Preferably, the talc powder has a particle size of 4-15 μm, the hydrochloric acid concentration is 4 mol / L, the hydrofluoric acid concentration is 1.5 mol / L, the volume ratio of hydrochloric acid to hydrofluoric acid is (3-4):1, and the etching time is 0.5-1.5 hours.

[0015] By adopting the above scheme, the chemical etching effect is good, the talc powder obtained has a larger specific surface area, better ion exchange effect, more surface activated hydroxyl groups, better ion exchange effect, and is more stable in the system and less prone to sedimentation.

[0016] In one specific implementation, the talc powder is also modified with an epoxy silane coupling agent.

[0017] By adopting the above scheme, the modified epoxy silane coupling agent has better compatibility with the epoxy resin matrix, more uniform dispersion, and better protection of the matrix by the layered structure. At the same time, it can also participate in curing, resulting in a denser coating film that is less susceptible to salt spray penetration.

[0018] In one specific implementation, the mica iron oxide includes dopamine-modified mica iron oxide, and the preparation steps include: adding mica iron oxide to a dopamine hydrochloride solution, stirring evenly, adjusting the pH value, adding a silane coupling agent, and heating to react to obtain dopamine-modified mica iron oxide.

[0019] By adopting the above scheme, the modified mica iron oxide is more evenly and stably distributed in component B, the diffusion path of corrosive media is extended, dopamine participates in curing, the resulting coating film is more dense, the mica iron oxide is more stably maintained in the system in a tile-like stack, and the water vapor and corrosive media are effectively blocked.

[0020] In one specific implementation, the epoxy resin has an epoxy equivalent of 400-500 eq / 100g, and the curing agent is an amine curing agent with an amine value of 500-600 mgKOH / g.

[0021] By adopting the above scheme, the parameters of epoxy resin and curing agent are more suitable for the raw material settings of this application, and the resulting coating film is fully cured, with uniform tension, and is smooth, dense and stable.

[0022] In one specific implementation scheme, the mass ratio of epoxy resin, curing agent, epoxy-modified exchange talc, and dopamine-modified mica iron oxide is 35-40:12-15:3-4:0.5.

[0023] By adopting the above scheme, the modified talc powder and dopamine-modified mica iron oxide have a good curing effect. The resulting coating film has a stable and flat stacked structure of talc powder and mica iron oxide. The coating film is not prone to bubbling and cracking due to uneven tension. The coating film has more uniform tension and more stable salt spray resistance.

[0024] In one specific implementation, the average particle size of mica iron oxide is 5-20 μm.

[0025] By adopting the above scheme, the particle size of mica iron oxide is suitable for the raw material settings of this application, the distribution is uniform and stable, and the salt spray resistance is good.

[0026] Secondly, this application provides a method for preparing an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 hours, comprising the following steps: weighing raw materials of components A and B according to their respective mass proportions; mixing epoxy resin, n-butanol, and xylene; adding a dispersant; stirring at low speed for 5-10 minutes; adding iron oxide red and anti-rust pigment and dispersing until there is no dry powder on the liquid surface; stirring at high speed for 25-35 minutes; sealing and soaking for 1-1.5 hours; stirring at high speed for 10-15 minutes; adding the remaining raw materials of component A under medium-speed stirring; continuing to stir for 5-10 minutes to obtain component A; stirring raw materials of component B at medium speed for 10-15 minutes; adding them to component A; mixing evenly to obtain an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 hours.

[0027] By adopting the above scheme, the preparation method is simple, the components in the coating are evenly and stably dispersed, and it is not easy to precipitate, thus providing a good protective effect on the substrate.

[0028] In one specific implementation, the low-speed stirring speed is 50-300 r / min, the medium-speed stirring speed is 350-450 r / min, and the high-speed stirring speed is 500-1000 r / min.

[0029] By adopting the above scheme, the raw material settings of this application are more suitable, the raw materials are mixed evenly, the molecular structure is not damaged, the bubble control effect of the coating is better, and the coating is smoother and flatter after curing.

[0030] In summary, this application has the following beneficial effects:

[0031] This application specifies in detail the components and mass fractions of the coating with epoxy resin as the main component, so that the resulting coating has good protective effects on the substrate, including physical barrier, passivation film protection, and anode and cathode protection. At the same time, by using calcium ion exchange talc, cerium ion exchange talc, and lanthanum ion exchange talc in a certain mass ratio, the layered structures with different densities are arranged alternately, and ions with different redox activities form a passivation film in sequence. The resulting coating film has both good protective effect and relatively uniform tension, is not easy to peel off, and has a good maze effect.

[0032] By further modifying talc powder with an epoxy silane coupling agent and modifying mica iron oxide in component B with dopamine, both of them participate in curing. By further limiting the parameters of epoxy resin and curing agent and their mass ratio, the resulting coating is fully cured, has uniform tension, is dense and not prone to cracking and peeling, and the resulting coating film can stably achieve high salt spray resistance.

[0033] This application also provides a method for preparing the coating, which involves adding different raw materials sequentially and limiting the stirring speed to achieve uniform mixing without damaging the molecular structure, resulting in fewer air bubbles and further improving the salt spray resistance of the prepared coating. Detailed Implementation

[0034] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0035] To further aid in understanding the technical solution of the present invention, several specific embodiments are provided to describe the technical solution of the present invention in more detail. All described embodiments are only some embodiments of the present invention, not all of them; embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The following embodiments are further illustrations of the present invention, but the present invention is not limited thereto.

[0036] Unless otherwise specified, the chemical reagents used in the examples and comparative examples are commercially available conventional reagents. The epoxy resin with an epoxy equivalent of 450-500 eq / 100g was purchased from Baling Petrochemical CYD-011; the curing agent with an amine value of 500-600 mg KOH / g was purchased from Baling Petrochemical T31; the dispersant was purchased from BYK-104S (Germany); and the leveling agent was purchased from BYK-VP-354 (Germany).

[0037] Preparation Example

[0038] Preparation Example 1: Ion-exchanged talc:

[0039] Calcium ion exchange talc:

[0040] Add 50g of 1000-mesh talc powder to 120ml of 0.8 mol / L CaCl2 solution, stir at 120r / min for 2.5 hours at 90℃, filter, wash with deionized water, and dry at 80℃ to obtain calcium ion exchange talc powder.

[0041] Cerium ion-exchange talc:

[0042] Add 50g of 1000-mesh talc powder to 120ml of 0.8 mol / L Ce(NO3)3 solution, stir at 120r / min for 2.5 hours at 90℃, filter, wash with deionized water, dry at 80℃ and pulverize to obtain cerium ion-exchange talc powder.

[0043] Lanthanum ion-exchange talc

[0044] Add 50g of 1000-mesh talc powder to 120ml of 0.8 mol / L La(NO3)3 solution, stir at 120r / min for 2.5 hours at 90℃, filter, wash with deionized water, and dry at 80℃ to obtain lanthanum ion-exchanged talc powder.

[0045] Preparation Example 2: Ion-exchange chemical etching of talc powder:

[0046] Mix 90 ml of 4 mol / L hydrochloric acid and 30 ml of 1.5 mol / L hydrofluoric acid evenly, add 50 g of 1000 mesh talc powder, stir evenly, filter after 1 hour, wash, and dry at 80℃ to obtain chemical etching talc powder for later use.

[0047] Calcium ion exchange chemical etching of talc:

[0048] Add 50g of 1000-mesh chemical etching talc powder to 120ml of 0.8 mol / L CaCl2 solution, stir at 120r / min for 2.5 hours at 90℃, filter, wash with deionized water, and dry at 80℃ to obtain calcium ion exchange chemical etching talc powder.

[0049] Cerium ion exchange chemical etching of talc:

[0050] Add 50g of 1000-mesh chemical etching talc powder to 120ml of 0.8 mol / L Ce(NO3)3 solution, stir at 120r / min for 2.5 hours at 90℃, filter, wash with deionized water, and dry at 80℃ to obtain cerium ion exchange chemical etching talc powder.

[0051] Lanthanum ion exchange chemical etching talc

[0052] Add 50g of 1000-mesh chemically etched talc powder to 120ml of 0.8 mol / L La(NO3)3 solution, stir at 120r / min for 2.5 hours at 90℃, filter, wash with deionized water, and dry at 80℃ to obtain lanthanum ion-exchange chemically etched talc powder.

[0053] Preparation Example 3: Epoxy silane coupling agent modified ion-exchange chemical etching talc powder:

[0054] Epoxy silane coupling agent modified calcium ion exchange chemical etching talc:

[0055] 50g of the calcium ion exchange chemical etching talc powder prepared in Preparation Example 2 was added to 1100ml of 60%wt ethanol aqueous solution, and then ultrasonically dispersed at 300W for 30 minutes. Then, 18g of silane coupling agent KH-172 was added, and the mixture was stirred at 85℃ for 3 hours. The mixture was then filtered, washed with deionized water, and dried to obtain epoxy silane coupling agent modified calcium ion exchange chemical etching talc powder.

[0056] Cerium ion exchange chemical etching of talc:

[0057] 50g of the cerium ion exchange chemical etching talc powder prepared in Preparation Example 2 was added to 1100ml of 60%wt ethanol aqueous solution, and then ultrasonically dispersed at 300W for 30 minutes. Then, 18g of silane coupling agent KH-172 was added, and the mixture was stirred at 85℃ for 3 hours. The mixture was then filtered, washed with deionized water, and dried to obtain epoxy silane coupling agent modified cerium ion exchange chemical etching talc powder.

[0058] Lanthanum ion-exchange chemical etching of talc:

[0059] 50g of the lanthanum ion-exchange chemically etched talc powder prepared in Example 2 was added to 1100ml of 60%wt ethanol aqueous solution, and then ultrasonically dispersed at 300W for 30 minutes. Then, 18g of silane coupling agent KH-172 was added, and the mixture was stirred at 85℃ for 3 hours. The mixture was then filtered, washed with deionized water, and dried to obtain epoxy silane coupling agent modified lanthanum ion-exchange chemically etched talc powder.

[0060] Preparation Example 4: Epoxy silane coupling agent modified chemically etched talc:

[0061] 50g of the chemically etched talc powder prepared in Example 2 was added to 1100ml of 60%wt ethanol aqueous solution, and then ultrasonically dispersed at 300W for 30 minutes. Then 18g of silane coupling agent KH-172 was added, and the mixture was stirred at 85℃ for 3 hours. The mixture was then filtered, washed with deionized water, and dried to obtain epoxy silane coupling agent modified chemically etched talc powder.

[0062] Preparation Example 5: Dopamine-modified mica iron oxide:

[0063] 50g of mica iron oxide with an average particle size of 10μm was added to 800ml of ethanol, ultrasonically washed at 300W for 30 minutes, filtered, washed with deionized water, and dried at 80℃ to obtain pretreated mica iron oxide. Then, 2g of dopamine hydrochloride was dissolved in 1000ml of Tris-HCl buffer, stirred evenly, the pH was adjusted to 8.5, and the reaction was stirred at room temperature for 6 hours. After centrifugation, the mixture was washed with deionized water and vacuum dried at 60℃ to obtain dopamine-modified mica iron oxide.

[0064] Example

[0065] Example 1

[0066] Component A: 35g epoxy resin, 2.5g n-butanol, 5g xylene, 0.5g dispersant, 10g iron oxide red, 6g heavy calcium carbonate, 2g zinc oxide, 6g rust-inhibiting silica powder, 4g kaolin, 1.3g calcium ion-exchange talc powder prepared in Preparation Example 1, 1.3g cerium ion-exchange talc powder prepared in Preparation Example 1, 1.3g lanthanum ion-exchange talc powder prepared in Preparation Example 1, 7g rust-inhibiting pigment, 15g precipitated barium sulfate, 4g petroleum resin, 0.06g leveling agent;

[0067] Component B: 12g curing agent, 1g n-butanol, 1.5g xylene, 1g dispersant, 0.6g mica iron oxide.

[0068] Weigh the raw materials of components A and B separately according to their mass proportions and set aside. Mix the epoxy resin, n-butanol, and xylene, add the dispersant, and stir at 200 r / min for 8 min. Add iron oxide red and anti-rust pigment and disperse until there is no dry powder on the liquid surface. Stir at 800 r / min for 20 min, seal and soak for 1 h, and stir at 400 r / min for 10 min. Add the remaining raw materials of component A while stirring at 400 r / min, and continue stirring for 10 min to obtain component A. Stir the raw materials of component B at 400 r / min for 12 min and add them to component A. Mix evenly to obtain an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 h.

[0069] Example 2

[0070] Component A: 40g epoxy resin, 2g n-butanol, 5.5g xylene, 0.1g dispersant, 12g iron oxide red, 4g heavy calcium carbonate, 4g zinc oxide, 4g rust-inhibiting silica powder, 6g kaolin, 1g calcium ion-exchange talc powder prepared in Preparation Example 1, 1g cerium ion-exchange talc powder prepared in Preparation Example 1, 1g lanthanum ion-exchange talc powder prepared in Preparation Example 1, 8g rust-inhibiting pigment, 12g precipitated barium sulfate, 5g petroleum resin, 0.02g leveling agent;

[0071] Component B: 15g curing agent, 2g n-butanol, 1g xylene, 3g dispersant, 0.4g mica iron oxide.

[0072] Weigh the raw materials of components A and B separately according to their mass proportions and set aside. Mix the epoxy resin, n-butanol, and xylene, add the dispersant, and stir at 200 r / min for 8 min. Add iron oxide red and anti-rust pigment and disperse until there is no dry powder on the liquid surface. Stir at 800 r / min for 20 min, seal and soak for 1 h, and stir at 400 r / min for 10 min. Add the remaining raw materials of component A while stirring at 400 r / min, and continue stirring for 10 min to obtain component A. Stir the raw materials of component B at 400 r / min for 12 min and add them to component A. Mix evenly to obtain an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 h.

[0073] Example 3

[0074] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 1.2g calcium ion-exchange talc powder prepared in Preparation Example 1, 1.2g cerium ion-exchange talc powder prepared in Preparation Example 1, 1.2g lanthanum ion-exchange talc powder prepared in Preparation Example 1, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent;

[0075] Component B: Curing agent 13.5g, n-butanol 1.5g, xylene 1.2g, dispersant 2g, mica iron oxide 0.5g.

[0076] Weigh the raw materials of components A and B separately according to their mass proportions and set aside. Mix the epoxy resin, n-butanol, and xylene, add the dispersant, and stir at 200 r / min for 8 min. Add iron oxide red and anti-rust pigment and disperse until there is no dry powder on the liquid surface. Stir at 800 r / min for 20 min, seal and soak for 1 h, and stir at 400 r / min for 10 min. Add the remaining raw materials of component A while stirring at 400 r / min, and continue stirring for 10 min to obtain component A. Stir the raw materials of component B at 400 r / min for 12 min and add them to component A. Mix evenly to obtain an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 h.

[0077] Example 4

[0078] The only difference between this embodiment and embodiment 3 is that:

[0079] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 0.72g calcium ion-exchange talc powder prepared in Preparation Example 1, 1.44g cerium ion-exchange talc powder prepared in Preparation Example 1, 1.44g lanthanum ion-exchange talc powder prepared in Preparation Example 1, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent;

[0080] Component B: Curing agent 13.5g, n-butanol 1.5g, xylene 1.2g, dispersant 2g, mica iron oxide 0.5g.

[0081] Example 5

[0082] The only difference between this embodiment and embodiment 3 is that:

[0083] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 1.44g calcium ion-exchange talc powder prepared in Preparation Example 1, 1.44g cerium ion-exchange talc powder prepared in Preparation Example 1, 0.72g lanthanum ion-exchange talc powder prepared in Preparation Example 1, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent;

[0084] Component B: Curing agent 13.5g, n-butanol 1.5g, xylene 1.2g, dispersant 2g, mica iron oxide 0.5g.

[0085] Example 6

[0086] The only difference between this embodiment and embodiment 3 is that:

[0087] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 0.72g calcium ion exchange chemical etching talc powder prepared in Preparation Example 2, 1.44g cerium ion exchange chemical etching talc powder prepared in Preparation Example 2, 1.44g lanthanum ion exchange chemical etching talc powder prepared in Preparation Example 2, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent; Component B: 13.5g curing agent, 1.5g n-butanol, 1.2g xylene, 2g dispersant, 0.5g mica iron oxide.

[0088] Example 7

[0089] The only difference between this embodiment and embodiment 3 is that:

[0090] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 0.72g of epoxy-silane coupling agent modified calcium ion exchange chemical etching talc obtained in Preparation Example 3, 1.44g of epoxy-silane coupling agent modified cerium ion exchange chemical etching talc obtained in Preparation Example 3, 1.44g of epoxy-silane coupling agent modified lanthanum ion exchange chemical etching talc obtained in Preparation Example 3, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent;

[0091] Component B: Curing agent 13.5g, n-butanol 1.5g, xylene 1.2g, dispersant 2g, mica iron oxide 0.5g.

[0092] Example 8

[0093] The only difference between this embodiment and embodiment 3 is that:

[0094] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 0.72g of epoxy-silane coupling agent modified calcium ion exchange chemical etching talc obtained in Preparation Example 3, 1.44g of epoxy-silane coupling agent modified cerium ion exchange chemical etching talc obtained in Preparation Example 3, 1.44g of epoxy-silane coupling agent modified lanthanum ion exchange chemical etching talc obtained in Preparation Example 3, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent;

[0095] Component B: 13.5g curing agent, 1.5g n-butanol, 1.2g xylene, 2g dispersant, and 0.5g dopamine-modified mica iron oxide prepared in Preparation Example 4.

[0096] Example 9

[0097] The only difference between this embodiment and embodiment 3 is that:

[0098] Component A: 38g epoxy resin, 2.2g n-butanol, 5.2g xylene, 0.3g dispersant, 11g iron oxide red, 5g heavy calcium carbonate, 3g zinc oxide, 5g rust-inhibiting silica powder, 5g kaolin, 0.72g of epoxy-silane coupling agent modified calcium ion exchange chemical etching talc obtained in Preparation Example 3, 1.44g of epoxy-silane coupling agent modified cerium ion exchange chemical etching talc obtained in Preparation Example 3, 1.44g of epoxy-silane coupling agent modified lanthanum ion exchange chemical etching talc obtained in Preparation Example 3, 7.5g rust-inhibiting pigment, 13g precipitated barium sulfate, 4.5g petroleum resin, 0.04g leveling agent;

[0099] Component B: 13.5g curing agent, 1.5g n-butanol, 1.2g xylene, 2g dispersant, and 0.6g dopamine-modified mica iron oxide prepared in Preparation Example 4.

[0100] Comparative Example

[0101] Comparative Example 1

[0102] Component A: 35g epoxy resin, 2.5g n-butanol, 5g xylene, 0.5g dispersant, 10g iron oxide red, 6g heavy calcium carbonate, 2g zinc oxide, 6g rust-inhibiting silica powder, 4g kaolin, 3.9g calcium ion exchange talc powder prepared in Example 1, 7g rust-inhibiting pigment, 15g precipitated barium sulfate, 4g petroleum resin, 0.06g leveling agent;

[0103] Component B: 12g curing agent, 1g n-butanol, 1.5g xylene, 1g dispersant, 0.6g mica iron oxide.

[0104] Weigh the raw materials of components A and B according to their respective mass proportions and set aside. Mix the epoxy resin, n-butanol, and xylene, add the dispersant, and stir at 200 r / min for 8 min. Add iron oxide red and anti-rust pigment and disperse until there is no dry powder on the liquid surface. Stir at 800 r / min for 20 min, seal and soak for 1 h, and stir at 400 r / min for 10 min. Add the remaining raw materials of component A while stirring at 400 r / min, and continue stirring for 10 min to obtain component A. Stir the raw materials of component B at 400 r / min for 12 min and add them to component A. Mix evenly to obtain the epoxy coating.

[0105] Comparative Example 2

[0106] Component A: 35g epoxy resin, 2.5g n-butanol, 5g xylene, 0.5g dispersant, 10g iron oxide red, 6g heavy calcium carbonate, 2g zinc oxide, 6g rust-inhibiting silica powder, 4g kaolin, 3.9g chemical etching talc powder modified with epoxy silane coupling agent obtained in Preparation Example 4, 7g rust-inhibiting pigment, 15g precipitated barium sulfate, 4g petroleum resin, 0.06g leveling agent;

[0107] Component B: 12g curing agent, 1g n-butanol, 1.5g xylene, 1g dispersant, 0.6g mica iron oxide.

[0108] Weigh the raw materials of components A and B according to their respective mass proportions and set aside. Mix the epoxy resin, n-butanol, and xylene, add the dispersant, and stir at 200 r / min for 8 min. Add iron oxide red and anti-rust pigment and disperse until there is no dry powder on the liquid surface. Stir at 800 r / min for 20 min, seal and soak for 1 h, and stir at 400 r / min for 10 min. Add the remaining raw materials of component A while stirring at 400 r / min, and continue stirring for 10 min to obtain component A. Stir the raw materials of component B at 400 r / min for 12 min and add them to component A. Mix evenly to obtain the epoxy coating.

[0109] Performance testing

[0110] The coating samples prepared in the examples and comparative examples were coated on steel plates with a dry film thickness of 60 μm. After curing at room temperature for 24 hours, the following tests were performed:

[0111] The salt spray resistance of the coating was tested according to GB / T10125;

[0112] The adhesion grade of the coating was tested in accordance with GB / T1720-1979;

[0113] The artificial weathering resistance of the coating was tested in accordance with GB / T1865-2009 (Cycle A).

[0114] The test results are summarized in Table 1.

[0115] Table 1

[0116] Salt spray resistance (h) Adhesion rating Resistant to artificial climate aging, 200h Example 1 1210 3 qualified Example 2 1230 3 qualified Example 3 1220 3 qualified Example 4 1390 2 qualified Example 5 1190 2 qualified Example 6 1470 2 qualified Example 7 1580 2 qualified Example 8 1730 1 qualified Example 9 1700 2 qualified Comparative Example 1 876 4 Unqualified Comparative Example 2 801 3 Unqualified

[0117] As can be seen from Examples 1-3 and Comparative Examples 1-2 and Table 1, this application achieves good salt spray resistance by specifying the composition and mass fraction of the coating with epoxy resin as the main component, using calcium ion exchange talc, cerium ion exchange talc, and lanthanum ion exchange talc together, and by adding different raw materials in sequence and limiting the stirring speed, the coating can be stirred evenly without destroying the molecular structure.

[0118] As can be seen from Examples 3-6 and Table 1, this application further improves the stability and salt spray resistance of the coating by first chemically etching the talc powder and limiting the mass ratio of calcium ion exchange talc powder, cerium ion exchange talc powder, and lanthanum ion exchange talc powder.

[0119] As can be seen from Examples 3 and 7-9 and Table 1, this application modifies ion-exchange chemically etched talc powder with epoxy silane coupling agents and mica iron oxide with dopamine, making it more uniform and stable in the system. At the same time, it limits the epoxy value of epoxy resin, the amine value of curing agent, and the mass ratio of the four components, so that the modified filler participates in the curing process and the coating film has uniform tension, a denser and more stable film, and good protective effect.

[0120] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A phosphorus-free, salt spray resistant epoxy coating for 1000 hours, characterized in that: It includes component A and component B; component A includes the following raw materials in parts by weight: epoxy resin 35-40 parts, n-butanol 2-2.5 parts, xylene 5-5.5 parts, dispersant 0.1-0.5 parts, iron oxide red 10-12 parts, heavy calcium carbonate 4-6 parts, zinc oxide 2-4 parts, rust-inhibiting silica powder 4-6 parts, kaolin 4-6 parts, talc powder 3-4 parts, ST rust-inhibiting pigment 7-8 parts, precipitated barium sulfate 12-15 parts, petroleum resin 4-5 parts, leveling agent 0.02-0.06 parts; component B includes... The raw materials include the following parts by weight: 12-15 parts curing agent, 1-2 parts n-butanol, 1-1.5 parts xylene, 1-3 parts dispersant, and 0.4-0.6 parts mica iron oxide; the talc powder includes calcium ion exchange chemically etched talc powder, cerium ion exchange chemically etched talc powder, and lanthanum ion exchange chemically etched talc powder; the mass ratio of the calcium ion exchange chemically etched talc powder, cerium ion exchange chemically etched talc powder, and lanthanum ion exchange chemically etched talc powder is 1:(1.5-2.5):(2-2.1).

2. The phosphorus-free, salt spray resistant (1000h) environmentally friendly epoxy coating according to claim 1, characterized in that: The epoxy resin has an epoxy equivalent of 400-500 eq / 100g, and the curing agent is an amine curing agent with an amine value of 500-600 mgKOH / g.

3. The phosphorus-free, salt spray resistant (1000h) environmentally friendly epoxy coating according to claim 1, characterized in that: The average particle size of the mica iron oxide is 5-20 μm.

4. A method for preparing a phosphorus-free, salt spray resistant (1000h) environmentally friendly epoxy coating as described in any one of claims 1-3, characterized in that: The process includes the following steps: Weigh the raw materials of components A and B according to their respective mass proportions and set aside. Mix the epoxy resin, n-butanol, and xylene, add the dispersant, and stir at low speed for 5-10 minutes. Add iron oxide red and ST anti-rust pigment and disperse until there is no dry powder on the liquid surface. Then stir at high speed for 25-35 minutes, seal and soak for 1-1.5 hours, and stir at high speed for 10-15 minutes. Add the remaining raw materials of component A under medium speed stirring and continue stirring for 5-10 minutes to obtain component A. Stir the raw materials of component B at medium speed for 10-15 minutes and add them to component A. Mix evenly to obtain an environmentally friendly epoxy coating that is phosphorus-free and resistant to salt spray for 1000 hours. The low-speed stirring speed is 50-300 r / min, the medium-speed stirring speed is 350-450 r / min, and the high-speed stirring speed is 500-1000 r / min.