Corrosion-resistant epoxy resin coating and method for producing the same

Abstract

The application belongs to the technical field of epoxy resin coatings, and particularly relates to a kind of corrosion-resistant epoxy resin coatings and a preparation method thereof.A kind of corrosion-resistant epoxy resin coatings, the corrosion-resistant epoxy resin coatings is prepared from the following raw materials in mass percentage: 30-38% of base material, 20-24% of compounded curing agent, 20-23% of solvent, 8-10% of compounded filler, 1-3% of functional additive, and deionized water is supplemented to 100%; wherein the base material is itaconic anhydride modified bisphenol A type epoxy resin; the compounded curing agent is composed of methylhexahydrophthalic anhydride and cashew phenol modified amine; the solvent is propylene glycol methyl ether acetate; and the compounded filler is composed of phosphorus iron powder and talc powder.The prepared coating has excellent performance in adhesion, impact resistance, salt spray corrosion resistance, moisture resistance, chemical resistance and the like due to the cooperation of the raw materials.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin coating technology, specifically relating to a corrosion-resistant epoxy resin coating and its preparation method. Background Technology

[0002] Epoxy resin coatings are high-performance coatings that use epoxy resin as the main film-forming substance and form a three-dimensional network structure through a cross-linking reaction with a curing agent. Their main components include epoxy resin base, curing agent, solvent, filler, and functional additives. Epoxy resin molecules contain active groups such as epoxy and hydroxyl groups, which endow the coating with adhesion, mechanical strength, and chemical corrosion resistance. Due to their outstanding comprehensive performance, epoxy resin coatings are widely used for protection in heavily corrosive environments such as ships, bridges, chemical equipment, and underground pipelines.

[0003] Traditional epoxy resin coatings are typically based on bisphenol A type epoxy resins and are cured at room temperature or high temperature using amine or anhydride curing agents. The solvents used are often high-volatile organic compounds (VOCs) such as toluene and xylene, which pose serious hazards to the environment and human health. The curing agents mainly rely on petrochemical raw materials, which does not meet the requirements of sustainable development. In addition, conventional fillers (such as silica and talc) have limited physical barrier capabilities against corrosive media, and long-term exposure to acid, alkali, and salt spray environments can easily lead to coating failure.

[0004] In recent years, existing technologies have proposed some improvement solutions to address the above problems:

[0005] a. Using water as a dispersant reduces VOC emissions, but water-based systems have problems such as slow curing speed and poor water resistance, making it difficult to meet the needs of heavily corrosive scenarios.

[0006] b. The shielding performance can be improved by adding nanofillers such as graphene and carbon nanotubes, but nanomaterials are difficult to disperse and have high costs, which will increase the production cost of the coating.

[0007] c. Use bio-based curing agents such as cashew phenol modified amine, but a single curing agent is difficult to balance room temperature curing speed and high temperature resistance.

[0008] Based on the above problems, there is an urgent need to develop a new type of corrosion-resistant epoxy resin coating. Summary of the Invention

[0009] The purpose of this invention is to provide a corrosion-resistant epoxy resin coating and its preparation method, so as to solve the problems existing in the prior art of epoxy resin coatings.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A corrosion-resistant epoxy resin coating, by weight percentage, is prepared from the following raw materials: 30-38% base material, 20-24% compound curing agent, 20-23% solvent, 8-10% compound filler, 1-3% functional additives, and deionized water to 100%.

[0012] The base material is itaconic anhydride-modified bisphenol A type epoxy resin;

[0013] The compound curing agent is composed of methyl hexahydrophthalic anhydride and cashew phenol modified amine;

[0014] The solvent is propylene glycol methyl ether acetate;

[0015] The compound filler is composed of ferrophosphorus powder and talc powder.

[0016] Furthermore, the preparation method of the itaconic anhydride modified bisphenol A epoxy resin includes the following steps:

[0017] a. After purging the air with nitrogen three times in the reactor, set the stirring speed to 200 rpm and heat the bisphenol A epoxy resin reactor to 70°C.

[0018] b. Add itaconic anhydride, maintain the temperature at 70℃, and stir at 200 rpm for 30 min; add the catalyst 1-butyl-3-methylimidazolium acetate, and stir at 200 rpm for 10 min;

[0019] c. Heat to 80°C, start reflux condensation, and continuously purge with nitrogen for protection. After reacting for 3 hours, cool down to 50°C, stop stirring, and let stand for 15 minutes. The mixture forms an upper organic phase and a lower aqueous phase.

[0020] d. Add 1 / 3 volume of deionized water to the reactor, stir at 200 rpm for 10 min to fully dissolve the catalyst in the water, let stand for 20 min, drain the lower aqueous phase containing the catalyst, repeat 3 times, then remove the water from the aqueous phase by vacuum distillation and recover the catalyst.

[0021] e. The upper organic phase is dehydrated at 80℃ and -0.095MPa until the moisture content is less than 0.1%, thus obtaining itaconic anhydride modified bisphenol A type epoxy resin.

[0022] Furthermore, the mass ratio of the methylhexahydrophthalic anhydride to the cashew phenol-modified amine is 5:3.

[0023] Furthermore, the mass ratio of the ferrophosphorus powder to the talc powder is 7:3.

[0024] Furthermore, the functional additives include leveling agents, defoamers, and silane coupling agents; wherein the leveling agent accounts for 0.5% of the total mass of the corrosion-resistant epoxy resin coating raw materials; the defoamer accounts for 0.3% of the total mass of the corrosion-resistant epoxy resin coating raw materials; and the silane coupling agent accounts for 1.5% of the total mass of the corrosion-resistant epoxy resin coating raw materials.

[0025] The present invention also provides a method for preparing the aforementioned corrosion-resistant epoxy resin coating, comprising the following steps:

[0026] S1. Add itaconic anhydride-modified bisphenol A epoxy resin and solvent to a dispersion tank and stir at 800 rpm for 15 min;

[0027] S2. Add ferric phosphorus powder and talc powder in sequence, increase the rotation speed to 2000 rpm, and disperse for 40 min; add silane coupling agent and disperse at 2000 rpm for 20 min;

[0028] S3. Reduce the speed to 1000 rpm, add leveling agent, defoamer, and deionized water, and stir for 10 minutes;

[0029] S4. Transfer the material to a sand mill for grinding and pass it through a 30μm sieve, then degas it under vacuum at 25℃ and -0.08MPa for 30 minutes;

[0030] S5. Add methyl hexahydrophthalic anhydride and cashew phenol modified amine, stir at 600 rpm for 20 min, and let stand for 5-10 min to obtain the corrosion-resistant epoxy resin coating.

[0031] The present invention also provides a coating method for the corrosion-resistant epoxy resin coating, specifically comprising: treating the surface of a metal substrate until it is clean and dry, and spraying or roller coating the corrosion-resistant epoxy resin coating until the wet film thickness is 100-120μm.

[0032] The present invention also provides a curing method for the corrosion-resistant epoxy resin coating, specifically: curing at room temperature for 24 hours, followed by curing at 80°C for 2 hours.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention utilizes itaconic anhydride-modified bisphenol A epoxy resin to significantly improve the coating's corrosion resistance, adhesion, and chemical resistance. Methylhexahydrophthalic anhydride forms an ester bond network at high temperatures, exhibiting excellent temperature resistance, while cashew phenol-modified amine accelerates curing at room temperature and enhances toughness. Together, these components improve the coating's impact resistance and hardness. Iron phosphate powder releases iron and phosphate ions, inhibiting electrochemical corrosion of the substrate, while the lamellar structure of talc extends the diffusion path of corrosive media. Together, these components significantly improve the coating's salt spray corrosion resistance. The synergistic effect of these raw materials results in a coating with excellent performance in terms of adhesion, impact resistance, salt spray corrosion resistance, damp heat resistance, and chemical resistance. Detailed Implementation

[0035] The technical solution of this invention patent will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0036] In the following embodiments, the bisphenol A type epoxy resin is EPON. TM 828; Cashew phenol modified amine model is Talc powder type HAR T84, the rest of the reagents are commercially available.

[0037] 1. The Influence of Different Raw Material Formulations on the Performance of Epoxy Resin Coatings

[0038] 1.1 Epoxy Resin Coating Raw Material Formulation

[0039] See Table 1.

[0040] Table 1. Raw material formulation for epoxy resin coatings (mass percentage)

[0041]

[0042] Note in Table 1: Modified epoxy resin is itaconic anhydride-modified bisphenol A type epoxy resin; unmodified epoxy resin is bisphenol A type epoxy resin.

[0043] 1.2 Itaconic anhydride modified bisphenol A type epoxy resin

[0044] The preparation method of itaconic anhydride modified bisphenol A epoxy resin in Table 1 includes the following steps:

[0045] a. After purging the reactor with nitrogen three times to replace the air, set the stirring speed to 200 rpm and heat the 76 kg bisphenol A epoxy resin reactor to 70℃;

[0046] b. Add 24 kg itaconic anhydride, maintain the temperature at 70℃, and stir at 200 rpm for 30 min; add 1.2 kg catalyst 1-butyl-3-methylimidazolium acetate, and stir at 200 rpm for 10 min;

[0047] c. Heat to 80°C, start reflux condensation, and continuously purge with nitrogen for protection. After reacting for 3 hours, cool down to 50°C, stop stirring, and let stand for 15 minutes. The mixture forms an upper organic phase and a lower aqueous phase.

[0048] d. Add 1 / 3 volume of deionized water to the reactor, stir at 200 rpm for 10 min to fully dissolve the catalyst in the water, let stand for 20 min, drain the lower aqueous phase containing the catalyst, repeat 3 times, then remove the water from the aqueous phase by vacuum distillation and recover the catalyst.

[0049] e. The upper organic phase is dehydrated at 80℃ and -0.095MPa until the moisture content is less than 0.1%, thus obtaining itaconic anhydride modified bisphenol A type epoxy resin.

[0050] 1.3 Epoxy Resin Coatings

[0051] The preparation method of epoxy resin coatings in Table 1 includes the following steps:

[0052] S1. Add itaconic anhydride-modified bisphenol A epoxy resin and propylene glycol methyl ether acetate to a dispersion tank and stir at 800 rpm for 15 min;

[0053] S2. Add ferric phosphorus powder and talc powder in sequence, increase the rotation speed to 2000 rpm, and disperse for 40 min; add silane coupling agent KH-550, and disperse at 2000 rpm for 20 min;

[0054] S3. Reduce the speed to 1000 rpm, add BYK-358 leveling agent, BYK-077 defoamer, and deionized water, and stir for 10 minutes;

[0055] S4. Transfer the material to a sand mill for grinding and pass it through a 30μm sieve, then degas it under vacuum at 25℃ and -0.08MPa for 30 minutes;

[0056] S5. Add methyl hexahydrophthalic anhydride and cashew phenol modified amine, stir at 600 rpm for 20 min, and let stand for 5-10 min to obtain the corrosion-resistant epoxy resin coating.

[0057] 1.4 Coating and Curing

[0058] The specific coating method is as follows: treat the surface of the metal substrate until it is clean and dry, spray or roll the corrosion-resistant epoxy resin coating until the wet film thickness is 100-120μm, and allow it to dry for 4 hours.

[0059] The curing method is as follows: cure at room temperature (25℃) for 24 hours, then cure at 80℃ for 2 hours.

[0060] 1.5 Determination of the properties of epoxy resin coatings

[0061] The test items are shown in Table 2, and the test results are shown in Table 3.

[0062] Table 2 Test Items, Test Methods, Basis and Explanation

[0063]

[0064]

[0065] Table 3. Effects of different raw material formulations on the properties of epoxy resin coatings

[0066]

[0067] Table 3 shows that, overall, coatings prepared from C7 raw materials exhibit excellent performance in terms of adhesion, impact resistance, salt spray corrosion resistance, damp heat resistance, and chemical resistance. This indicates that itaconic anhydride-modified bisphenol A epoxy resin significantly improves corrosion resistance, adhesion, and chemical resistance; methylhexahydrophthalic anhydride forms an ester bond network at high temperatures, resulting in excellent temperature resistance, while cashew phenol-modified amine accelerates curing at room temperature and enhances toughness; together, they improve the coating's impact resistance and hardness; iron phosphate powder releases iron and phosphate ions, inhibiting electrochemical corrosion of the substrate, while the lamellar structure of talc powder extends the diffusion path of corrosive media; together, they significantly improve the coating's salt spray corrosion resistance.

[0068] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A corrosion resistant epoxy coating, characterized by, The corrosion-resistant epoxy resin coating is prepared from the following raw materials in percentage by mass: base 30-38%, compounded curing agent 20-24%, solvent 20-23%, compounded filler 8-10%, functional additive 1-3%, and deionized water to make up 100%; The base is itaconic anhydride modified bisphenol A type epoxy resin; The compounded curing agent is composed of methylhexahydrophthalic anhydride and cashew phenol modified amine; The solvent is propylene glycol methyl ether acetate; The compounded filler is composed of phosphorus iron powder and talc powder; wherein, The preparation method of the itaconic anhydride modified bisphenol A type epoxy resin comprises the following steps: a. After replacing air with nitrogen for 3 times in a reaction kettle, set the stirring speed to 200 rpm, add bisphenol A type epoxy resin into the reaction kettle, and heat to 70℃; b. Add itaconic anhydride, keep the temperature at 70℃, and stir at 200 rpm for 30 min; add catalyst 1-butyl-3-methylimidazole acetate, and stir at 200 rpm for 10 min; c. Heat to 80℃, start condensation reflux, and continuously protect with nitrogen, react for 3 h, then cool to 50℃, stop stirring, and stand for 15 min, the mixture forms upper organic phase and lower water phase; d. Add deionized water with a volume of 1 / 3 of the organic phase into the reaction kettle, stir at 200 rpm for 10 min, make the catalyst fully dissolved in water, stand for 20 min, discharge the lower water phase containing the catalyst, repeat 3 times, then remove the water in the water phase under reduced pressure, and recover the catalyst; e. Dehydrate the upper organic phase at 80℃ and -0.095 MPa to a water content of less than 0.1%, and the itaconic anhydride modified bisphenol A type epoxy resin is obtained.

2. The corrosion resistant epoxy coating of claim 1, wherein, The mass ratio of the methylhexahydrophthalic anhydride and cashew phenol modified amine is 5:

3.

3. The corrosion resistant epoxy coating of claim 1, wherein, The mass ratio of the phosphorus iron powder and talc powder is 7:

3.

4. The corrosion resistant epoxy coating of claim 1, wherein, The functional additive includes leveling agent, defoaming agent, and silane coupling agent; wherein, the mass of the leveling agent accounts for 0.5% of the total mass of the raw materials of the corrosion-resistant epoxy resin coating; The mass of the defoaming agent accounts for 0.3% of the total mass of the raw materials of the corrosion-resistant epoxy resin coating; The mass of the silane coupling agent accounts for 1.5% of the total mass of the raw materials of the corrosion-resistant epoxy resin coating.

5. A process for the preparation of the corrosion resistant epoxy coating of claim 4, characterized by, The method comprises the following steps: S1. Add itaconic anhydride modified bisphenol A type epoxy resin and solvent into a dispersion tank, and stir at 800 rpm for 15 min; S2. Add phosphorus iron powder and talc powder in sequence, increase the speed to 2000 rpm, and disperse for 40 min; add silane coupling agent, and disperse at 2000 rpm for 20 min; S3. Reduce the speed to 1000 rpm, add leveling agent, defoaming agent, and deionized water, and stir for 10 min; S4. Transfer the material to a sand mill for grinding and pass through a 30 μm screen, then vacuum deaerate at 25℃ and -0.08 MPa for 30 min; S5. Add methylhexahydrophthalic anhydride and cashew phenol modified amine, stir at 600 rpm for 20 min, and stand for 5-10 min, and the corrosion-resistant epoxy resin coating is obtained.

6. A method of applying the corrosion resistant epoxy coating of any one of claims 1-4, characterized by, Specifically: the surface of the metal substrate is treated to be clean and dry, and the corrosion-resistant epoxy resin coating is sprayed or roller coated to a wet film thickness of 100-120 μm.

7. A method of curing the corrosion resistant epoxy coating of any one of claims 1-4, characterized by, Specifically: after curing at room temperature for 24 h, curing at 80℃ for 2 h.

Images