A zinc-rich curing agent, preparation method and application

Abstract

The application discloses a zinc-rich curing agent, a preparation method and application, the zinc-rich curing agent is made of ethylene amine compound, dimer acid, polyethylene glycol, fatty acid, polyether amine, diethanolamine, polyamide and epoxy resin; the preparation steps are: mixing ethylene amine compound, dimer acid and fatty acid, stirring, warming and reacting, and dehydrating through reduced pressure distillation; cooling, adding polyethylene glycol, stirring and warming and reacting; adding polyether amine, diethanolamine and polyamide, warming and reacting; cooling, adding epoxy resin, and then stirring; adding propylene glycol methyl ether to obtain the finished zinc-rich curing agent.The zinc-rich curing agent prepared by the application contains a polybasic polymeric amine mixture with a macromolecular structure, can help dispersing zinc powder, provides good stability, does not need to add too much cosolvent when preparing zinc-rich paint, and has excellent water resistance and salt mist resistance when being used with the resin.

Description

Technical Field

[0001] This invention belongs to the field of chemical coating technology, specifically relating to a zinc-rich curing agent, its preparation method, and its application. Background Technology

[0002] Epoxy zinc-rich base curing agent, also known as zinc-rich curing agent or zinc-rich base, is a new type of coating hardener widely used in the production of various anti-corrosion coatings and coatings with high wear resistance and high chemical resistance. Currently, conventional zinc-rich coating technologies mainly include those using resin to disperse zinc powder and those using curing agents to disperse zinc powder. Resin-dispersed zinc powder technology uses resin-dispersed zinc powder as the main agent, and then adds a curing agent on-site for emulsification. Its disadvantages include slow drying speed and high requirements for on-site mixing conditions. Currently, curing agent-dispersed zinc powder technology is more commonly used. However, the difficulty of curing agent-dispersed zinc powder technology lies in the poor encapsulation effect of the curing agent on the zinc powder, which easily leads to precipitation and affects the storage stability of zinc-rich coatings. Therefore, designing a reasonable structure for the zinc-rich curing agent is of great significance for the stability of zinc-rich coatings. Furthermore, conventional zinc-rich curing agents often fail to effectively reduce the viscosity of the system during the zinc powder dispersion process, resulting in zinc-rich coatings that are difficult to use. This necessitates the addition of relatively large amounts of solvent to improve the fluidity of the zinc-rich coating, leading to excessively high VOC (volatile organic compound) levels. This is harmful to the health of construction workers and severely pollutes the environment, causing significant environmental impact. Therefore, it is necessary to develop a new zinc-rich curing agent. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a zinc-rich curing agent, its preparation method, and its application. The multi-polymer amine mixture with a macromolecular structure can help disperse zinc powder and provide excellent stability. In the process of preparing zinc-rich coatings, it is not necessary to add excessive amounts of co-solvents. Furthermore, when used in conjunction with resins, it exhibits excellent water resistance and salt spray resistance.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, the present invention provides a zinc-rich curing agent comprising the following raw materials: ethylene amine compounds, dimer acid, polyethylene glycol, fatty acid, polyetheramine, diethanolamine, polyamide, and epoxy resin, wherein the ethylene amine compounds include one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0006] Preferably, by mass parts, the composition is: 8-12 parts of ethylene amine compound, 15-20 parts of dimer acid, 8-11 parts of polyethylene glycol, 3-5 parts of fatty acid, 4-7 parts of polyetheramine, 1-5 parts of diethanolamine, 5-12 parts of polyamide, and 12-15 parts of epoxy resin.

[0007] More preferably, by mass parts, there are 8-12 parts of ethylene amine compound, 15-20 parts of dimer acid, 10-11 parts of polyethylene glycol, 3-5 parts of fatty acid, 5-7 parts of polyetheramine, 1-5 parts of diethanolamine, 5-10 parts of polyamide, and 12-13 parts of epoxy resin.

[0008] More preferably, the number average molecular weight of the polyetheramine is 230 to 2000, and the number average molecular weight of the polyamide is 500 to 5000.

[0009] Preferably, the fatty acid is a fatty acid with 8 to 18 carbon atoms in its carbon chain.

[0010] In a second aspect, the present invention provides a method for preparing a zinc-rich curing agent, the specific steps of which are as follows:

[0011] (1) Mix ethylene amine compounds, dimer acids and fatty acids, stir and heat to 180-220°C, react at a constant temperature for 2-10 hours, and then dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0012] (2) Cool down to 110-120°C, add polyethylene glycol to the first intermediate product, stir and heat to 100-150°C, control the reaction time to 1-8 hours, and obtain the second intermediate product;

[0013] (3) Add polyetheramine, diethanolamine and polyamide to the second intermediate product at 150°C, heat to 150-180°C, mix and stir evenly for 1-5 hours to obtain the third intermediate product.

[0014] (4) Cool the third intermediate product to 100-120°C, add epoxy resin, and then stir to react to obtain the fourth intermediate product.

[0015] (5) Cool the fourth intermediate product to 80°C and add propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0016] Preferably, in step (1), the stirring speed is 100-150 rpm, preferably 120 rpm, to ensure that the reactants are mixed evenly; in step (2), after adding polyethylene glycol, the stirring speed is 100-150 rpm, preferably 120 rpm; and in step (4), after adding epoxy resin, the stirring speed is 200-300 rpm.

[0017] Preferably, in step (5), the propylene glycol methyl ether content in the zinc-rich curing agent is 20%, and the viscosity of the zinc-rich curing agent is 1000-20000 cP.

[0018] In a third aspect, the present invention proposes an application of a zinc-rich curing agent, wherein the zinc-rich curing agent prepared above is used to prepare a zinc-rich coating, and the specific steps are as follows:

[0019] Component A: Mix zinc-rich curing agent, silica gel, bentonite, talc, zinc powder, dispersant and co-solvent evenly;

[0020] Component B: Epoxy emulsion;

[0021] Component A and component B are mixed and stirred evenly at a mass ratio of 10:(1~5) to obtain a zinc-rich coating.

[0022] Beneficial effects:

[0023] The zinc-rich curing agent prepared by this invention contains a mixture of multi-polymer amines with a macromolecular structure, which can help disperse zinc powder and provide good stability. In the process of preparing zinc-rich coatings, it is not necessary to add too much co-solvent. At the same time, when used with resin, it has excellent water resistance and salt spray resistance. Attached Figure Description

[0024] Figure 1 The results of a 1500-hour salt spray test are shown for zinc-rich primer.

[0025] Figure 2 The results of impact and flexibility tests on zinc-rich primer are shown.

[0026] Figure 3 The figure shows the GPC data for the zinc-rich curing agent in Preparation Example 1. Detailed Implementation

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are merely some embodiments of the present invention. For those skilled in the art, other implementation methods can be obtained based on these drawings without creative effort.

[0028] This invention proposes a zinc-rich curing agent comprising the following raw materials: ethylene amine compounds, dimer acid, polyethylene glycol, fatty acids, polyetheramine, diethanolamine, polyamide, and epoxy resin, wherein the ethylene amine compounds include one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0029] Specifically, by mass parts, the composition is as follows: 8-12 parts ethylene amine compounds, 15-20 parts dimer acid, 8-11 parts polyethylene glycol, 3-5 parts fatty acids, 4-7 parts polyetheramine, 1-5 parts diethanolamine, 5-12 parts polyamide, and 12-15 parts epoxy resin.

[0030] This invention uses the above-mentioned raw materials to prepare a novel high molecular weight and macromolecular structure multi-component polymeric amine mixture. This multi-component polymeric amine mixture helps to disperse zinc powder when formulating zinc-rich coatings. The mechanism of action of this invention will be explained below with reference to specific preparation methods.

[0031] This invention proposes a method for preparing a zinc-rich curing agent, the specific steps of which are as follows:

[0032] (1) Mix ethylene amine compounds, dimer acids and fatty acids, stir and heat to 180-220°C, react at a constant temperature for 2-10 hours, and then dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0033] (2) Cool down to 110-120°C, add polyethylene glycol to the first intermediate product, stir and heat to 100-150°C, control the reaction time to 1-8 hours, and obtain the second intermediate product;

[0034] (3) Add polyetheramine, diethanolamine and polyamide to the second intermediate product at 150°C, heat to 150-180°C, mix and stir evenly for 1-5 hours to obtain the third intermediate product.

[0035] (4) Cool the third intermediate product to 100-120°C, add epoxy resin, and then stir to react to obtain the fourth intermediate product.

[0036] (5) Cool the fourth intermediate product to 80°C and add propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0037] In step (1), ethylene amine compounds react with dimer acids to generate polyamides or polyamide amines, with fatty acids playing a role in increasing the molecular weight. Additionally, fatty acids also have hydrophilic properties, which is beneficial for adjusting the HLB value of zinc-rich coatings.

[0038] The first intermediate product contains both fatty acids that participate in the reaction capping and free fatty acids. The free fatty acids are beneficial for coating zinc powder during the preparation of zinc-rich coatings, thus ensuring uniform dispersion of the zinc powder.

[0039] Specifically, fatty acids are those with 8 to 18 carbon atoms in their carbon chains, such as oleic acid and lauric acid. The amount of fatty acids used should not be excessive, as too much fatty acid will significantly reduce the viscosity of the zinc-rich curing agent.

[0040] In step (1), the stirring speed is 100-150 rpm to ensure that the reactants are mixed evenly.

[0041] In step (2), the first intermediate product undergoes chain extension and grafting to increase the molecular weight. Polyethylene glycol is grafted onto the first intermediate product. Polyethylene glycol is hydrophilic, which is beneficial for adjusting the HLB value of the zinc-rich curing agent. In addition, the addition of polyethylene glycol can also achieve the purpose of increasing the molecular weight.

[0042] Polyethylene glycol can react with the free fatty acids of the first intermediate. In addition, ethylene amine compounds react with dimer acids to form polyamides or polyamide amines. Grafted dimer acids can also react with the hydroxyl groups of polyethylene glycol to further increase the molecular weight.

[0043] In step (3), the roles of polyetheramine, diethanolamine, and polyamide are to adjust the performance of the zinc-rich curing agent. Specifically, polyetheramine can improve the toughness of the zinc-rich curing agent, as well as improve the dispersibility of zinc powder during the preparation of zinc-rich coatings and adjust the HLB value of the zinc-rich curing agent. Polyamide can improve the dispersibility and sag performance of the zinc-rich curing agent for zinc powder. The role of diethanolamine is to fill the gaps between polyetheramine, polyamide, and the second intermediate product, and improve the dispersibility of the zinc-rich curing agent.

[0044] In the absence of polyetheramine, the dispersibility of zinc-rich curing agent for zinc powder decreases significantly. In the absence of polyamide, the dispersibility of zinc-rich curing agent for zinc powder decreases, and the sag performance fails to meet the standards. In the absence of diethanolamine, the dispersibility of zinc-rich coatings prepared using zinc-rich curing agent deteriorates.

[0045] Furthermore, in this invention, the number average molecular weight of the polyetheramine is 230–2000, and the number average molecular weight of the polyamide is 500–5000; preferably, the molecular weight of the polyamide is 500–2000. Excessively high molecular weights of the polyetheramine and polyamide can lead to excessively high viscosity in the zinc-rich curing agent.

[0046] In step (4), epoxy resin chain extender is added. The epoxy groups after epoxy resin chain extension can provide better compatibility in the application of zinc-rich coatings and can also improve the overall strength of the paint film.

[0047] Some epoxy resins can also react with polyetheramines, polyamides, and diethanolamines, improving the compatibility of the components in the system.

[0048] In step (4), after adding epoxy resin, the stirring speed is 200 rpm. If the stirring speed is too slow when adding epoxy resin, the performance of the zinc-rich curing agent will be reduced.

[0049] The role of propylene glycol methyl ether added in step (5) is to reduce the viscosity of the zinc-rich curing agent, allowing it to be used normally. It should be noted that although propylene glycol methyl ether is also a solvent, in this invention, only a suitable amount is added to the zinc-rich curing agent to reduce viscosity, while only a small amount of solvent is added when preparing the zinc-rich coating. From the perspective of the zinc-rich coating, the problem of excessive VOCs (volatile organic compounds) caused by the zinc-rich coating is effectively solved.

[0050] In this invention, the mass ratio of propylene glycol methyl ether to the fourth intermediate is 2:8, that is, in the zinc-rich curing agent, the mass fraction of propylene glycol methyl ether is 20%, and the remaining 80% is solids. The viscosity of the zinc-rich curing agent is 1000-20000 cP.

[0051] The zinc-rich curing agent prepared by the present invention has an HLB of 1 to 5, and more preferably, the HLB of the zinc-rich curing agent is 3 to 4, which is beneficial to balancing the construction performance.

[0052] This invention also proposes the application of a zinc-rich curing agent, wherein the zinc-rich curing agent prepared above is used to prepare a zinc-rich coating, and the specific steps are as follows:

[0053] Component A: Mix zinc-rich curing agent, fumed silica, bentonite, talc, zinc powder, dispersant and co-solvent evenly;

[0054] Component B: Epoxy emulsion;

[0055] Zinc-rich coating is prepared by mixing and stirring components A and B at a mass ratio of 10:(1-5). Preferably, components A and B are mixed and stirred at a mass ratio of 10:3.

[0056] The dispersant is ADDITOL-VXW 6208 from Zhanxin Dispersant, and the cosolvent is dipropylene glycol butyl ether.

[0057] Specifically, in component A, by mass parts, there are 5.2 to 6.2 parts of zinc-rich curing agent, 0.5 to 1.5 parts of fumed silica, 0.2 to 0.8 parts of bentonite, 1 to 3 parts of talc, 55 to 90 parts of zinc powder, 0.4 to 1.0 parts of dispersant, and 4 to 13 parts of co-solvent.

[0058] More preferably, in component A, by mass parts, there are 5.2 to 6.2 parts of zinc-rich curing agent, 0.5 to 1.5 parts of fumed silica, 0.2 to 0.8 parts of bentonite, 1 to 3 parts of talc, 55 to 82 parts of zinc powder, 0.4 to 1.0 parts of dispersant, and 8 to 13 parts of co-solvent.

[0059] The technical solution of the present invention will be described in detail below with specific embodiments.

[0060] Preparation Example 1

[0061] (1) Add 100g tetraethylenepentamine, 200g dimer acid and 50g oleic acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, dehydrate by vacuum distillation for 1 hour, dehydrate about 20g, and obtain the first intermediate product.

[0062] (2) Cool down to 110-120℃, add 80g of polyethylene glycol, stir at 120rpm and heat up to 150℃ to start the reaction, control the reaction time to not exceed 3 hours, and obtain the second intermediate product.

[0063] (3) At 150°C, 60g of polyetheramine, 20g of diethanolamine and 120g of polyamide were added to the second intermediate product, the temperature was raised to 180°C and the reaction was carried out for 2 hours to obtain the third intermediate product.

[0064] (4) Cool the third intermediate product to 100-120°C, add 150g of epoxy resin in two batches, and stir the reaction at 200rpm to obtain the fourth intermediate product.

[0065] (5) Cool the fourth intermediate product to 80°C and add 190g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0066] GPC data of zinc-rich curing agent finished product as follows Figure 3 As shown.

[0067] Preparation Example 2

[0068] (1) Add 89g of triethylenetetramine, 178g of dimer acid and 45g of oleic acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, and dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0069] (2) Cool down to 100-120℃, add 105g of polyethylene glycol, stir at 120rpm and heat to 150℃ to start the reaction. Control the reaction time to not exceed 4 hours to obtain the second intermediate product.

[0070] (3) At 150°C, 56g of polyetheramine, 16g of diethanolamine and 85g of polyamide were added to the second intermediate product, the temperature was raised to 180°C and the reaction was carried out for 2 hours to obtain the third intermediate product.

[0071] (4) Cool the third intermediate product to 100-120°C, add 128g of epoxy resin in two batches, and stir the reaction at 200rpm to obtain the fourth intermediate product.

[0072] (5) Cool the fourth intermediate product to 80°C and add 176g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0073] Preparation Example 3

[0074] (1) Add 45g of triethylenetetramine, 50g of triethylenetetramine, 192g of dimer acid and 48g of oleic acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, and dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0075] (2) Cool down to 100-120℃, add 126g of polyethylene glycol, stir at 120rpm and heat to 150℃ to start the reaction. Control the reaction time to not exceed 5 hours to obtain the second intermediate product.

[0076] (3) At 150°C, 58g of polyetheramine, 18g of diethanolamine and 105g of polyamide were added to the second intermediate product, the temperature was raised to 180°C and the reaction was carried out for 2 hours to obtain the third intermediate product.

[0077] (4) Cool the third intermediate product to 100-120°C, add 136g of epoxy resin in two batches, and stir the reaction at 200rpm to obtain the fourth intermediate product.

[0078] (5) Cool the fourth intermediate product to 80°C and add 178g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0079] Preparation Example 4

[0080] (1) Add 89g of triethylenetetramine, 178g of dimer acid and 33g of lauric acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, and dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0081] (2) Cool down to 100-120℃, add 105g of polyethylene glycol, stir at 120rpm and heat up to 150℃ to start the reaction, and obtain the second intermediate product.

[0082] (3) At 150°C, 56g of polyetheramine, 16g of diethanolamine and 85g of polyamide were added to the second intermediate product, the temperature was raised to 180°C and the reaction was carried out for 2 hours to obtain the third intermediate product.

[0083] (4) Cool the third intermediate product to 100-120°C, add 128g of epoxy resin in two batches, and stir the reaction at 200rpm to obtain the fourth intermediate product.

[0084] (5) Cool the fourth intermediate product to 80°C and add 176g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0085] Preparation of Comparative Example 1

[0086] (1) Add 89g of triethylenetetramine, 178g of dimer acid and 45g of oleic acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, and dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0087] (2) Cool down to 100-120℃, add 105g of polyethylene glycol, stir at 120rpm and heat up to 150℃ to start the reaction and obtain the second intermediate product.

[0088] (3) At 150°C, 16g of diethanolamine and 85g of polyamide were added to the second intermediate, the temperature was raised to 180°C, and the reaction was carried out for 2 hours to obtain the third intermediate.

[0089] (4) Cool the third intermediate product to 100-120°C, add 128g of epoxy resin in two batches, and stir the reaction at 200rpm to obtain the fourth intermediate product.

[0090] (5) Cool the fourth intermediate product to 80°C and add 162g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0091] The zinc-rich curing agent has a solid content of 80% and a viscosity of 1500–20000 cP.

[0092] Preparation of Comparative Example 2

[0093] (1) Add 89g of triethylenetetramine, 178g of dimer acid and 45g of oleic acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, and dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0094] (2) Cool down to 100-120℃, add 105g of polyethylene glycol, stir at 120rpm and heat up to 150℃ to start the reaction. Control the reaction time to not exceed 3 hours to obtain the second intermediate product.

[0095] (3) At 150°C, 56g of polyetheramine and 85g of polyamide were added to the second intermediate product, the temperature was raised to 180°C, and the reaction was carried out for 2 hours to obtain the third intermediate product.

[0096] (4) Cool the third intermediate product to 100-120°C, add 128g of epoxy resin in two batches, stir at 200rpm, heat to 150°C, start the reaction, control the reaction time to not exceed 3 hours, and obtain the fourth intermediate product.

[0097] (5) Cool the fourth intermediate product to 80°C and add 172g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0098] Preparation of Comparative Example 3

[0099] (1) Add 89g of triethylenetetramine, 178g of dimer acid and 45g of oleic acid to a 1L glass reactor, stir at 120rpm and heat to 220℃, react at a constant temperature for 8 hours, and dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product.

[0100] (2) Cool down to 100-120℃, add 105g of polyethylene glycol, stir at 120rpm and heat up to 150℃ to start the reaction and obtain the second intermediate product.

[0101] (3) At 150°C, 56g of polyetheramine and 16g of diethanolamine were added to the second intermediate product, the temperature was raised to 180°C, and the reaction was carried out for 2 hours to obtain the third intermediate product.

[0102] (4) Cool the third intermediate product to 100-120°C, add 128g of epoxy resin in two batches, and stir the reaction at 200rpm to obtain the fourth intermediate product.

[0103] (5) Cool the fourth intermediate product to 80°C and add 135g of propylene glycol methyl ether to obtain the zinc-rich curing agent product.

[0104] Application Example 1

[0105] Using the zinc-rich curing agent obtained in Preparation Example 1 as a raw material, and commercially available JT-WBE521 as an epoxy emulsion, a zinc-rich primer was prepared. The specific steps are as follows:

[0106] Prepare component A: 6.2 parts zinc-rich curing agent, 1.0 part silica, 0.6 parts bentonite, 2 parts talc, 85 parts zinc powder, 0.6 parts dispersant, and 4.6 parts co-solvent. Mix the above raw materials evenly.

[0107] Component B was prepared as an epoxy emulsion, JT-WBE521.

[0108] Preparation of the paint film: After preparing components A and B, mix components A and B evenly in a mass ratio of 10:3, stir at 500 rpm for 5 minutes, and prepare the paint film on the cold-rolled plate by air spraying. The dry film thickness is controlled at 50 μm, and the VOC does not exceed 250 g / L. After air drying for 7 days at 25°C / 50% RH, the salt spray performance is tested.

[0109] The neutral salt spray test was conducted according to the ASTM-B117 standard. After marking the salt spray plate with an X, it was placed in a salt spray chamber for testing. The test results after 1500 hours of salt spray testing are as follows: Figure 1 As shown. 1500 hours of salt spray data demonstrates that the zinc-rich curing agent designed in this invention exhibits excellent salt spray performance, with no rust or blistering on the entire board surface. Stability was primarily tested by assessing the storage stability of the zinc-rich coating; 1 kg of zinc-rich coating was placed in a 50°C oven for 30 days, and the presence of sediment at the bottom was observed.

[0110] Impact and flexibility tests showed that the dry film thickness was 20 μm, the forward and reverse impact was greater than 50 kg·cm, and the bending was less than 1 mm without cracking, indicating that the zinc-rich curing agent of the present invention has excellent flexibility.

[0111] Application Comparative Example 1

[0112] Commercially available zinc-rich curing agent A was selected as the raw material. A has a solid content of 78% and a viscosity of 2000 cP. Commercially available JT-WBE521 was used as the epoxy emulsion to prepare the zinc-rich primer. The specific steps are as follows:

[0113] Prepare component A: 6.2 parts zinc-rich curing agent, 1.0 part silica, 0.6 parts bentonite, 2 parts talc, 85 parts zinc powder, 0.6 parts dispersant, and 6.2 parts co-solvent. Mix the above raw materials evenly.

[0114] Component B was prepared as an epoxy emulsion, JT-WBE521.

[0115] Preparation of the paint film: After preparing components A and B, mix components A and B evenly in a mass ratio of 10:3, stir at 500 rpm for 5 minutes, and prepare the paint film on the cold-rolled plate by air spraying. The dry film thickness is controlled at 50 μm, and the VOC exceeds 350 g / L. After air drying for 7 days at 25°C / 50% RH, the salt spray performance is tested.

[0116] Application Comparative Example 2

[0117] Using the zinc-rich curing agent prepared in Comparative Example 1 as a raw material, and commercially available JT-WBE521 as an epoxy emulsion, a zinc-rich primer was prepared. The specific steps are as follows:

[0118] Prepare component A: 6.2 parts zinc-rich curing agent, 1.0 part silica, 0.6 parts bentonite, 2 parts talc, 85 parts zinc powder, 0.6 parts dispersant, and 4.6 parts co-solvent. Mix the above raw materials evenly.

[0119] Component B was prepared as an epoxy emulsion, JT-WBE521.

[0120] Preparation of the paint film: After preparing components A and B, mix components A and B evenly in a mass ratio of 10:3, stir at 500 rpm for 5 minutes, and prepare the paint film on the cold-rolled plate by air spraying. The dry film thickness is controlled at 50 μm, and the VOC does not exceed 250 g / L. After air drying for 7 days at 25°C / 50% RH, the salt spray performance is tested.

[0121] Application Comparative Example 3

[0122] Using the zinc-rich curing agent prepared in Comparative Example 2 as a raw material, and commercially available JT-WBE521 as an epoxy emulsion, a zinc-rich primer was prepared. The specific steps are as follows:

[0123] Prepare component A: 6.2 parts zinc-rich curing agent, 1.0 part silica, 0.6 parts bentonite, 2 parts talc, 85 parts zinc powder, 0.6 parts dispersant, and 4.6 parts co-solvent. Mix the above raw materials evenly.

[0124] Component B was prepared as an epoxy emulsion, JT-WBE521.

[0125] Preparation of the paint film: After preparing components A and B, mix components A and B evenly in a mass ratio of 10:3, stir at 500 rpm for 5 minutes, and prepare the paint film on the cold-rolled plate by air spraying. The dry film thickness is controlled at 50 μm, and the VOC does not exceed 250 g / L. After air drying for 7 days at 25°C / 50% RH, the salt spray performance is tested.

[0126] Application Comparative Example 4

[0127] Using the zinc-rich curing agent prepared in Comparative Example 3 as a raw material, and commercially available JT-WBE521 as an epoxy emulsion, a zinc-rich primer was prepared. The specific steps are as follows:

[0128] Prepare component A: 6.2 parts zinc-rich curing agent, 1.0 part silica, 0.6 parts bentonite, 2 parts talc, 85 parts zinc powder, 0.6 parts dispersant, and 4.6 parts co-solvent. Mix the above raw materials evenly.

[0129] Component B was prepared as an epoxy emulsion, JT-WBE521.

[0130] Preparation of the paint film: After preparing components A and B, mix components A and B evenly in a mass ratio of 10:3, stir at 500 rpm for 5 minutes, and prepare the paint film on the cold-rolled plate by air spraying. The dry film thickness is controlled at 50 μm, and the VOC does not exceed 250 g / L. After air drying for 7 days at 25°C / 50% RH, the salt spray performance is tested.

[0131] The test results of Application Example 1 and Application Comparative Examples 1-4 are shown in Table 1 below.

[0132] Table 1 Performance Test Results

[0133]

[0134]

[0135] As shown in Table 1, the zinc-rich curing agent prepared in this invention can effectively reduce the VOCs of coatings when applied to the preparation of paint primers. Furthermore, the polyetheramine, diethanolamine, and polyamide of this invention have a direct impact on the performance of the curing agent. The absence of any one of these components significantly reduces the curing agent's performance, resulting in poor stability and a tendency to precipitate or agglomerate. Simultaneously, the zinc powder coating efficiency decreases in the absence of raw materials such as polyetheramine, diethanolamine, and polyamide during the preparation of zinc-rich coatings. Therefore, poor zinc powder coating can negatively impact storage stability, particularly at high temperatures where zinc powder agglomeration is likely. If the zinc powder is well dispersed, the resulting paint film after emulsification with epoxy resin exhibits good uniformity and high density, leading to better salt spray performance.

[0136] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A zinc-rich curing agent, characterized in that, The product comprises, by weight parts, the following raw materials: 8-12 parts of ethylene amine compounds, 15-20 parts of dimer acid, 8-11 parts of polyethylene glycol, 3-5 parts of fatty acids, 4-7 parts of polyetheramine, 1-5 parts of diethanolamine, 5-12 parts of polyamide, and 12-15 parts of epoxy resin. The ethylene amine compounds include one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, and the polyetheramine has a molecular weight of 230-2000. The preparation method includes the following steps: (1) Mix ethylene amine compounds, dimer acids and fatty acids, stir and heat to 180-220°C, react at a constant temperature for 2-10 hours, and then dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product. (2) Cool down to 110-120°C, add polyethylene glycol to the first intermediate product, stir and heat to 100-150°C, control the reaction time to 1-8 hours, and obtain the second intermediate product; (3) Add polyetheramine, diethanolamine and polyamide to the second intermediate product, heat to 150-180°C, mix and stir for 1-5 hours to obtain the third intermediate product; (4) Cool the third intermediate product to 100-120°C, add epoxy resin, and then stir to react to obtain the fourth intermediate product. (5) Cool the fourth intermediate product and add propylene glycol methyl ether to obtain the zinc-rich curing agent product.

2. The zinc-rich curing agent according to claim 1, characterized in that, The molecular weight of polyamide is 500 to 5000.

3. The zinc-rich curing agent according to claim 1, characterized in that, Fatty acids are fatty acids with 8 to 18 carbon atoms in their carbon chain.

4. A method for preparing a zinc-rich curing agent, characterized in that, The steps for preparing the zinc-rich curing agent as described in any one of claims 1-3 are as follows: (1) Mix ethylene amine compounds, dimer acids and fatty acids, stir and heat to 180-220°C, react at a constant temperature for 2-10 hours, and then dehydrate by vacuum distillation for 1 hour to obtain the first intermediate product. (2) Cool down to 110-120°C, add polyethylene glycol to the first intermediate product, stir and heat to 100-150°C, control the reaction time to 1-8 hours, and obtain the second intermediate product; (3) Add polyetheramine, diethanolamine and polyamide to the second intermediate product, heat to 150-180°C, mix and stir for 1-5 hours to obtain the third intermediate product; (4) Cool the third intermediate product to 100-120°C, add epoxy resin, and then stir to react to obtain the fourth intermediate product. (5) Cool the fourth intermediate product and add propylene glycol methyl ether to obtain the zinc-rich curing agent product.

5. The preparation method according to claim 4, characterized in that, In step (5), the mass fraction of propylene glycol methyl ether in the zinc-rich curing agent is 20%, and the viscosity of the zinc-rich curing agent is 1000-20000 cP.

6. An application of a zinc-rich curing agent, characterized in that, Zinc-rich coatings are prepared using the zinc-rich curing agent as described in any one of claims 1-3.

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