Chemical-resistant epoxy resin coating and preparation method thereof

Abstract

The present application relates to the field of coatings, and in particular to a chemical-resistant epoxy resin coating and a preparation method thereof. The chemical-resistant epoxy resin coating comprises, by weight, 80 to 100 parts of an epoxy resin composition, 15 to 25 parts of a curing agent, 15 to 25 parts of modified nanoparticles, 2 to 5 parts of an anti-settling agent, 1 to 3 parts of a leveling agent, 1 to 2 parts of a defoaming agent, 5 to 10 parts of a pigment and filler, and 20 to 40 parts of a diluent. The epoxy resin coating prepared by the present application not only has excellent adhesion, but also maintains excellent chemical resistance, water resistance, moisture resistance, and aging resistance. It can meet the performance requirements of various existing industries for epoxy resin coatings, thereby greatly expanding the application of epoxy resin coatings and having very excellent application value.

Description

Technical Field

[0001] The present application relates to the field of coatings, and in particular to an epoxy resin coating resistant to chemical corrosion and a preparation method thereof. Background Art

[0002] With the development of industrial technology, the requirements for chemical resistance, corrosion resistance, and mechanical properties of materials are becoming increasingly stringent. Especially in the fields of chemical, pharmaceutical, and marine engineering, equipment and structural components are often exposed to harsh chemical environments. Therefore, protective coatings that can effectively resist the corrosion of various chemicals are needed to extend their service life and ensure safe operation.

[0003] Epoxy resin coatings are widely used in the aforementioned fields due to their excellent adhesion, chemical resistance, and good mechanical strength. Epoxy resin is a thermosetting polymer that forms a three-dimensional network structure by reacting with a curing agent, thereby providing excellent physical and chemical properties. However, as application environments become increasingly harsh, traditional epoxy resin coatings still have shortcomings under certain extreme conditions. For example, in highly corrosive environments such as strong acids, strong bases, or solvents, traditional epoxy resin coatings may swell, dissolve, or delaminate, resulting in a decrease in protective effectiveness. In addition, some high-performance chemicals may penetrate into the coating, destroying the bond between the coating and the substrate, further affecting the long-term stability and reliability of the coating.

[0004] Although the epoxy resin coatings currently available on the market can meet the requirements of use in most cases, the following problems still exist when facing extreme chemical corrosion. For example, in specific strong acid, strong alkali or organic solvent environments, traditional epoxy resin coatings may not be able to maintain their integrity and are prone to chemical degradation or physical damage, resulting in failure of the protective function; the waterproof and anti-penetration capabilities are limited. For certain highly permeable environments, existing epoxy resin coatings may not be able to effectively prevent moisture and solutions with moisture as the carrier from penetrating the coating, thereby causing aging and corrosion of the substrate.

[0005] Therefore, in order to effectively solve the above problems, the present application provides an epoxy resin coating resistant to chemical corrosion and a preparation method thereof. The epoxy resin coating prepared in the present application not only has excellent adhesion, but also can maintain excellent chemical corrosion resistance, waterproofness, moisture resistance and aging resistance. It can meet the performance requirements of various industries for epoxy resin coatings, thereby greatly expanding the application of epoxy resin coatings, and thus has very excellent application value. Summary of the Invention

[0006] In order to solve the above problems, the first aspect of the present application provides an epoxy resin coating resistant to chemical corrosion. The raw materials are, in parts by mass: 80 to 100 parts of epoxy resin composition, 15 to 25 parts of curing agent, 15 to 25 parts of modified nanoparticles, 2 to 5 parts of anti-settling agent, 1 to 3 parts of leveling agent, 1 to 2 parts of defoaming agent, 5 to 10 parts of pigment and filler, and 20 to 40 parts of diluent.

[0007] As a preferred solution, the mass ratio of the epoxy resin composition, the curing agent and the modified nanoparticles is (85-95): (18-22): (20-24).

[0008] As a preferred solution, the mass ratio of the epoxy resin composition, the curing agent and the modified nanoparticles is (88~94): (18~20): (22~24).

[0009] As a preferred solution, the epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin.

[0010] As a preferred solution, the mass ratio of the bisphenol A epoxy resin, epoxy block resin and modified epoxy resin is (60-70): (10-15): (10-15).

[0011] As a preferred solution, the mass ratio of the bisphenol A epoxy resin, epoxy block resin and modified epoxy resin is (65-70): (10-12): (14-15).

[0012] As a preferred solution, the epoxy equivalent of the bisphenol A epoxy resin is 220-240 g / eq.

[0013] As a preferred solution, the viscosity of the bisphenol A epoxy resin is 8000-12000 mPa·s at 25°C.

[0014] As a preferred solution, the epoxy block resin is an ethylene oxide-propylene oxide block copolymer resin.

[0015] As a preferred solution, the weight average molecular weight of the epoxy block resin is 2000~4000Da.

[0016] As a preferred solution, the ethylene oxide block content of the epoxy block resin is 30-35 wt%.

[0017] As a preferred solution, the preparation method of the modified epoxy resin specifically includes the following steps: S1: adding the base epoxy resin to a reactor with a stirring device, heating it to 80-90°C to completely melt it, then adding DMF and continuing to stir until it is evenly mixed; S2: slowly adding 4,4'-diaminodiphenyl ether while stirring at a speed of 80-100 rpm, and continuing to stir for 30-35 minutes after the addition is completed; S3: adding triethylamine, maintaining the temperature at 85-95°C, and continuing to stir and react for 2-4 hours. After the reaction is completed, stopping heating, allowing the mixture to cool naturally to room temperature, and passing the obtained product through a 400-600 mesh sieve to remove unreacted solid particles and other impurities, and then transferring it to a clean container, sealing it and storing it to avoid contact with air and moisture.

[0018] As a preferred solution, the matrix epoxy resin is E-51 or E-44.

[0019] As a preferred solution, the mass ratio of the matrix epoxy resin, 4,4'-diaminodiphenyl ether and triethylamine is (60-70): (10-20): (0.5-1).

[0020] As a preferred solution, the preparation method of the modified nanoparticles specifically comprises the following steps: S1: titanium dioxide and zinc nitrate hexahydrate are mixed and added to DMF, glutaric anhydride and tetraisopropoxy titanate are added, the temperature is raised to 75-80°C and kept warm for 2-2.5 hours, ammonia water is added to adjust the pH to 8-8.5, triethylamine, ethyl orthosilicate and ethanol are added, the temperature is kept at 60-65°C for 1.5-2 hours, and after the reaction is completed, the product is filtered and washed to obtain pre-modified particles; S2: the pre-modified particles are added to DMF and mixed. The mixture was stirred at 50-60 rpm for 20-30 min until uniform, and then the temperature was raised to 80-90 ° C and kept warm for 1-1.5 h. The DMF solution containing 1,4-diaminobenzene was then added dropwise for 1-1.5 h. After completion, the reaction vessel was heated at a constant speed of 3-4 ° C to 110-130 ° C and kept warm for 14-16 h. After the reaction was completed, it was naturally cooled to room temperature and the product was filtered, washed with deionized water and acetone 2-3 times, and vacuum-dried at 70-80 ° C.

[0021] As a preferred solution, the mass ratio of titanium dioxide, zinc nitrate hexahydrate, glutaric anhydride and tetraisopropoxy titanate is (1.5-2): (4-5): (1.5-2): (0.2-0.4).

[0022] As a preferred solution, the mass ratio of titanium dioxide, zinc nitrate hexahydrate, triethylamine and ethyl orthosilicate is (1.5-2): (4-5): (0.05-0.1): (0.4-0.5).

[0023] As a preferred solution, the mass ratio of the pre-modified particles, 1,4-phthalic acid and 1,4-diaminobenzene is (3-4): (1.8-2.2): (0.6-0.8).

[0024] As a preferred solution, the average particle size of the titanium dioxide is 10-15 nm; the average particle size of the modified nanoparticles is 550-650 nm.

[0025] The modified nanoparticles prepared in this application can effectively improve the aging resistance, corrosion resistance, and waterproof and moisture resistance of epoxy resin coatings. The modified nanoparticles can form spherical particles through the coating effect of titanium dioxide and amorphous silicon dioxide, realizing the embedding of tiny nanoparticles on the surface of the framework structure. The formation of this composite structure can greatly improve the guiding effect of the nanoparticles on water molecules, thereby directly guiding water molecules to the structure of the framework particles for absorption in the early stage of contact with water. This absorption effect does not desorb at the ambient temperature of daily use, and after adsorption saturation, it can form a barrier with external water molecules through the surface particle coating, thereby directly removing water molecules and active groups that penetrate into the surface in the early stage of the coating contacting a high humidity environment, thereby achieving isolation of water molecules on the coating surface, avoiding the formation of water molecule penetration pathways, and preventing the formation of a continuous hydration layer on the coating surface, thereby achieving excellent chemical resistance and waterproof and moisture resistance.

[0026] On the other hand, the modified nanoparticles prepared in the present application can achieve high-strength connection with the specific epoxy resin composition added in the present application through surface hydrogen bonding in the coating system, thereby greatly enhancing the stability of the modified nanoparticles in the coating system, avoiding the segregation and migration of modified particles in long-term use of the coating and extreme environments, and can also greatly reduce the micropores occupied by the modified nanoparticles, reduce the shaking of the nanoparticles, and maintain excellent particle stability in active environments such as high temperature and high humidity, thereby obtaining excellent coating aging resistance.

[0027] As a preferred solution, the anti-settling agent is at least one of fumed silica, hydrogenated castor oil, organic bentonite and polyamide wax.

[0028] As a preferred solution, the anti-settling agent is hydrogenated castor oil.

[0029] As a preferred solution, the leveling agent is at least one selected from the group consisting of an organic silicone leveling agent, a polyacrylate leveling agent, a polyether modified silicone oil leveling agent, and a polyester leveling agent.

[0030] As a preferred solution, the leveling agent is any one of the organosilicon leveling agents.

[0031] As a preferred solution, the defoaming agent is at least one of silicone defoaming agents.

[0032] As a preferred solution, the pigment filler is any one of titanium dioxide, iron oxide, carbon black, phthalocyanine blue, permanent red and ultramarine.

[0033] As a preferred solution, the pigment filler is phthalocyanine blue or titanium dioxide.

[0034] As a preferred solution, the diluent is a combination of xylene and ethylene glycol monobutyl ether.

[0035] As a preferred solution, the mass ratio of xylene to ethylene glycol monobutyl ether is (5-6): (1.5-2.5).

[0036] As a preferred solution, the mass ratio of xylene to ethylene glycol monobutyl ether is (5-5.5): (1.6-2.2).

[0037] The second aspect of the present application provides a method for preparing the above-mentioned chemical-resistant epoxy resin coating, which specifically includes the following steps: S1: adding the epoxy resin composition to a reactor with a stirring device, heating it to 80~90°C, and continuously stirring at 80~120rpm until it is completely melted and uniform, and slowly adding modified nanoparticles, anti-settling agent, leveling agent and defoaming agent under stirring and continuing to stir for 30~40min to ensure that all solid particles are fully dispersed; S2: after adding the pigment and filler, stirring at a high speed of 400~600rpm for 60~80min; S3: cooling to room temperature, slowly adding the curing agent, and continuously stirring for 20~30min, and finally adding the diluent to mix the coating. After completion, pass it through a 400~600 mesh sieve, fill the obtained product into a container and seal it for storage.

[0038] This application has the following beneficial effects:

[0039] 1. The present application provides a chemical-resistant epoxy resin coating, which not only has excellent adhesion, but also maintains excellent chemical corrosion resistance, water resistance, moisture resistance, and aging resistance. It can meet the performance requirements of various industries for epoxy resin coatings, thereby greatly expanding the application of epoxy resin coatings and having very excellent application value.

[0040] 2. The present application provides an epoxy resin coating resistant to chemical corrosion, in which the modified nanoparticles added can form spherical particles through the coating effect of titanium dioxide and amorphous silicon dioxide, thereby realizing the embedding of tiny nanoparticles on the surface of the framework structure. The formation of this composite structure can greatly improve the guiding effect of the nanoparticles on water molecules, thereby directly guiding the water molecules to the structure of the framework particles for absorption in the early stage of contact with moisture. This absorption effect does not desorb at the ambient temperature of daily use, and after adsorption saturation, it can form a barrier with external water molecules through the surface particle coating, thereby directly removing the water molecules and active groups that penetrate into the surface in the early stage of the coating contacting a high humidity environment, thereby realizing the isolation of water molecules on the coating surface, avoiding the formation of water molecule penetration pathways, and making it impossible to form a continuous hydration layer on the coating surface, thereby obtaining excellent chemical resistance and waterproof and moisture resistance.

[0041] 3. The present application provides an epoxy resin coating resistant to chemical corrosion, in which the modified nanoparticles added can also achieve high-strength connection with the specific epoxy resin composition added in the present application through surface hydrogen bonding in the coating system, thereby greatly enhancing the stability of the modified nanoparticles in the coating system, avoiding the segregation and migration of modified particles during long-term use of the coating and in extreme environments, and can also greatly reduce the micropores occupied by the modified nanoparticles, reduce the shaking of the nanoparticles, and thus maintain excellent particle stability in active environments such as high temperature and high humidity, thereby obtaining excellent coating aging resistance. DETAILED DESCRIPTION

[0042] The following text further illustrates and demonstrates the technical solutions described in the above-mentioned summary of the invention in the form of specific implementation plans. The following examples are merely practical examples used to illustrate and explain the technical solutions in the specification and should not limit the scope of the claims to be protected by this application. All technical products based on the technical solutions described in the summary of the invention in this application should be included in the scope of protection to be protected by this application.

[0043] In the following examples, unless otherwise specified, the raw materials are all commercially available products or can be prepared by methods well known to those skilled in the art.

[0044] Example 1: Example 1 The first aspect provides an epoxy resin coating resistant to chemical corrosion. The raw materials are, in parts by mass: 90.8 parts of epoxy resin composition, 19.5 parts of curing agent, 23.2 parts of modified nanoparticles, 4.2 parts of anti-settling agent, 1.8 parts of leveling agent, 1.2 parts of defoaming agent, 8.5 parts of pigment and filler, and 25 parts of diluent.

[0045] The epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin, and the mass ratio of the three is 66:10:14.8.

[0046] The bisphenol A epoxy resin has an epoxy equivalent weight of 230 g / eq and a viscosity of 9500 mPa·s at 25° C. and was purchased from the Epon series of products with corresponding parameters sold by Hanson, USA.

[0047] The epoxy block resin is an ethylene oxide-propylene oxide block copolymer resin with a weight average molecular weight of 3000 Da and an ethylene oxide block content of 35 wt %, and is purchased from BASF, Germany, and is a model L64 product.

[0048] The preparation method of the modified epoxy resin specifically includes the following steps: S1: adding 65 parts of base epoxy resin E-44 to a reactor equipped with a stirring device, heating to 90°C to completely melt it, then adding 450 parts of DMF and continuing to stir until it is evenly mixed; S2: slowly adding 16.5 parts of 4,4'-diaminodiphenyl ether while stirring at a speed of 90 rpm, and continuing to stir for 30 minutes after the addition is completed; S3: adding 0.6 parts of triethylamine, maintaining the temperature at 92°C, and continuing to stir and react for 3 hours. After the reaction is completed, stopping heating, allowing the mixture to cool naturally to room temperature, and passing the obtained product through a 400-mesh sieve to remove unreacted solid particles and other impurities, and then transferring it to a clean container, sealing it and storing it to avoid contact with air and moisture.

[0049] The preparation method of modified nanoparticles specifically includes the following steps: S1: 1.8 parts of titanium dioxide and 4.6 parts of zinc nitrate hexahydrate are mixed and added to 120 parts of DMF, 1.6 parts of glutaric anhydride and 0.26 parts of tetraisopropoxy titanate are added, the temperature is raised to 75°C and kept warm for 2 hours, then ammonia water is added to adjust the pH to 8.4, then 0.06 parts of triethylamine, 0.5 parts of ethyl orthosilicate and 40 parts of ethanol are added, and the temperature is kept at 60°C for 2 hours. After the reaction is completed, the product is filtered and washed to obtain pre-modified particles; S2: 3.5 parts of pre-modified particles are mixed and kept warm for 2 hours. The mixture was added into 100 parts of DMF and mixed evenly, then 2.1 parts of 1,4-benzenedicarboxylic acid was added, stirred at 60 rpm for 25 min until uniform, then heated to 85 ° C and kept warm for 1 hour, and then a DMF solution containing 0.75 parts of 1,4-diaminobenzene (15 parts in total) was added dropwise for 1 hour. After completion, the reaction vessel was heated at a uniform speed from 4 ° C to 120 ° C and kept warm for 16 hours. After the reaction was completed, it was naturally cooled to room temperature and the product was filtered, washed with deionized water and acetone 3 times, and vacuum dried at 80 ° C.

[0050] The average particle size of titanium dioxide is 12 nm; the average particle size of the modified nanoparticles is 581 nm.

[0051] The anti-settling agent is hydrogenated castor oil; the leveling agent is silicone leveling agent BYK-333; the defoaming agent is silicone defoaming agent BYK-028; and the pigment and filler is phthalocyanine blue.

[0052] The diluent is a composition of xylene and ethylene glycol monobutyl ether, and the mass ratio of the two is 5.5:2.

[0053] The second aspect of this embodiment provides a method for preparing the above-mentioned epoxy resin coating resistant to chemical corrosion, which specifically includes the following steps: S1: adding the epoxy resin composition to a reactor with a stirring device, heating to 85°C, and continuously stirring at 100 rpm until it is completely melted and uniform, and slowly adding modified nanoparticles, anti-settling agent, leveling agent and defoaming agent under stirring and continuing to stir for 35 minutes to ensure that all solid particles are fully dispersed; S2: after adding the pigment and filler, stirring at a high speed of 600 rpm for 80 minutes; S3: cooling to room temperature, slowly adding the curing agent, and continuously stirring for 25 minutes, and finally adding the diluent to mix the coating. After completion, pass through a 500-mesh sieve, and fill the obtained product into a container and seal it for storage.

[0054] Example 2: The specific implementation method of this example is basically the same as that of Example 1, with the only difference being that the raw materials of the chemical-resistant epoxy resin coating, in parts by mass, are: 95 parts of epoxy resin composition, 22 parts of curing agent, 20.5 parts of modified nanoparticles, 3.9 parts of anti-settling agent, 1.8 parts of leveling agent, 1.2 parts of defoaming agent, 7.6 parts of pigment and filler, and 30 parts of diluent.

[0055] The epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin, and the mass ratio of the three is 70:10:15.

[0056] Example 3: The specific implementation method of this example is basically the same as that of Example 1, with the only difference being that the raw materials of the chemical-resistant epoxy resin coating, in parts by mass, are: 85 parts of epoxy resin composition, 18 parts of curing agent, 24 parts of modified nanoparticles, 4.0 parts of anti-settling agent, 1.6 parts of leveling agent, 1.1 parts of defoaming agent, 7.8 parts of pigment and filler, and 26 parts of diluent.

[0057] The epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin, and the mass ratio of the three is 60:10:15.

[0058] Comparative Example 1

[0059] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the raw materials of the epoxy resin coating resistant to chemical corrosion, in parts by mass, are: 120 parts of epoxy resin composition, 30 parts of curing agent, 12.5 parts of modified nanoparticles, 4.2 parts of anti-settling agent, 1.8 parts of leveling agent, 1.2 parts of defoaming agent, 8.5 parts of pigment and filler, and 25 parts of diluent.

[0060] The epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin, and the mass ratio of the three is 90:15:15.

[0061] Comparative Example 2

[0062] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the raw materials of the epoxy resin coating resistant to chemical corrosion, in parts by mass, are: 75 parts of epoxy resin composition, 8.5 parts of curing agent, 35.5 parts of modified nanoparticles, 4.2 parts of anti-settling agent, 1.8 parts of leveling agent, 1.2 parts of defoaming agent, 8.5 parts of pigment and filler, and 48 parts of diluent.

[0063] The epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin, and the mass ratio of the three is 50:10:15.

[0064] Comparative Example 3

[0065] The specific implementation of this comparative example is basically the same as that of Example 1, except that the epoxy block resin is an ethylene oxide-propylene oxide block copolymer resin with a weight-average molecular weight of 10,000 Da and an ethylene oxide block content of 80 wt %, purchased from BASF, Germany, model L88.

[0066] Comparative Example 4

[0067] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified epoxy resin specifically includes the following steps: S1: adding 95 parts of base epoxy resin E-44 to a reactor with a stirring device, heating to 90°C to completely melt it, and then adding 450 parts of DMF and continuing to stir until it is evenly mixed; S2: slowly adding 10 parts of 4,4'-diaminodiphenyl ether while stirring at 90 rpm, and continuing to stir for 30 minutes after the addition is completed; S3: adding 0.3 parts of triethylamine, maintaining the temperature at 92°C, and continuing to stir the reaction for 3 hours. After the reaction is completed, stop heating, let the mixture cool naturally to room temperature, and pass the obtained product through a 400-mesh sieve to remove unreacted solid particles and other impurities, and then transfer it to a clean container, seal it and store it to avoid contact with air and moisture.

[0068] Comparative Example 5

[0069] The specific implementation of this comparative example is basically the same as that of Example 1, except that the preparation method of the modified nanoparticles specifically comprises the following steps: S1: 0.6 parts of titanium dioxide and 4.6 parts of zinc nitrate hexahydrate are mixed and added to 120 parts of DMF, 1.6 parts of glutaric anhydride and 0.26 parts of tetraisopropoxy titanate are added, the temperature is raised to 75°C and kept warm for 2 hours, then ammonia water is added to adjust the pH to 8.4, then 0.02 parts of triethylamine, 0.2 parts of ethyl orthosilicate and 25 parts of ethanol are added, the temperature is kept at 60°C for 2 hours, and after the reaction is completed, the product is filtered and washed to obtain pre-modified nanoparticles. Particles; S2: Add 3.5 parts of pre-modified particles to 100 parts of DMF and mix evenly, then add 2.1 parts of 1,4-benzenedicarboxylic acid, stir at 60 rpm for 25 minutes until uniform, then heat to 85°C and keep warm for 1 hour, then add dropwise a DMF solution containing 0.75 parts of 1,4-diaminobenzene (15 parts in total), the addition time is 1 hour, after completion, heat the reaction vessel uniformly from 4°C to 120°C and keep warm for 16 hours, after the reaction is completed, naturally cool to room temperature and filter the product, wash with deionized water and acetone 3 times, and vacuum dry at 80°C.

[0070] Comparative Example 6

[0071] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified nanoparticles specifically comprises the following steps: S1: 1.8 parts of titanium dioxide and 4.6 parts of zinc nitrate hexahydrate are mixed and added to 120 parts of DMF, 1.6 parts of glutaric anhydride and 0.26 parts of tetraisopropoxy titanate are added, the temperature is raised to 75°C and kept warm for 2 hours, then ammonia water is added to adjust the pH to 8.4, then 0.06 parts of triethylamine, 0.5 parts of ethyl orthosilicate and 40 parts of ethanol are added, the temperature is kept at 60°C for 2 hours, and after the reaction is completed, the product is filtered and washed to obtain the pre-modified nanoparticles. S2: add 6 parts of pre-modified particles to 120 parts of DMF and mix evenly, then add 1.4 parts of 1,4-benzenedicarboxylic acid, stir at 60 rpm for 25 minutes until uniform, then heat to 85 ° C and keep warm for 1 hour, then add DMF solution containing 0.32 parts of 1,4-diaminobenzene (10 parts in total) dropwise for 1 hour, after completion, heat the reaction vessel uniformly from 4 ° C to 120 ° C and keep warm for 16 hours, after the reaction is completed, cool naturally to room temperature and filter the product, wash with deionized water and acetone 3 times, and vacuum dry at 80 ° C to obtain the product.

[0072] Comparative Example 7

[0073] The specific implementation of this comparative example is basically the same as that of Example 1, except that the average particle size of titanium dioxide is 30 nm; the average particle size of the modified nanoparticles is 774 nm.

[0074] Performance evaluation

[0075] Corrosion resistance (salt spray) test: After curing the epoxy resin coatings prepared in the examples and comparative examples, samples with a coating specification of 2 cm × 2 cm × 0.1 cm were prepared. 5 wt% NaCl was used as the test solution. The temperature conditions were 38 ± 2 ° C and the relative humidity was 90 ± 4%. The salt spray resistance test was carried out with an inclination angle of 20 °, uniform spraying, a spray pressure of 1.5 bar, and a test time of 800 h. After completion, whether there was blistering, oxidation, and cracking was observed. If so, it was unqualified, otherwise it was qualified. The pass rate of 50 groups of samples in each test is recorded in Table 1.

[0076] Temperature and humidity aging test: After the epoxy resin coatings prepared in the examples and comparative examples were cured, samples with a coating specification of 2 cm × 2 cm × 0.1 cm were prepared and placed in a constant temperature and humidity chamber at 70 ± 3 ° C and a relative humidity of 80 ± 3% for 6 months. Afterwards, the samples were observed for blistering, oxidation, and cracking. If any, the samples were unqualified, otherwise they were qualified. 50 groups of samples were tested in each group, and the qualified rate results were recorded in Table 1.

[0077] Waterproofness test: After curing the epoxy resin coatings prepared in the examples and comparative examples, a sample with a coating specification of 2 cm × 2 cm × 0.1 cm was prepared, a water droplet size of 2.5 μL, and a time of 30 s were used to obtain the water contact angle of the coating surface. The test value was the average of 10 tests and recorded in Table 1.

[0078] Color brightness test: The epoxy resin coatings prepared in the examples and comparative examples were coated on glass as a substrate and cured to form a coating, and then a brightness test was performed. The coating thickness was 0.1 mm. The brightness of the coating was tested using a brightness meter at a test angle of 60°. The measured values ​​were averaged over 10 tests and recorded in Table 1.

[0079] Table 1 Performance test results

[0080]

[0081] It can be seen from the examples and comparative examples of the present application and the data results in Table 1 that Examples 1 to 3 of the present application have obvious advantages over comparative examples 1 to 7 in terms of aging resistance, temperature resistance, corrosion resistance, waterproofness and moisture resistance, and coating brightness performance. This is mainly due to the combined effect of the modified nanoparticles, compounded epoxy resin composition and other matching technical solutions specified in the present application. Comparative examples 1 to 7 did not adopt the technical solution specified in the present application, resulting in obvious disadvantages in the above performance tests. This further proves the necessity of the technical solution specified in the present application for the technical effect of the present application and solving the technical problems.

Claims

1. A chemical-resistant epoxy resin coating, characterized in that: Chemical-resistant epoxy resin coating, the raw materials are, by weight: 80-100 parts of epoxy resin composition, 15-25 parts of curing agent, 15-25 parts of modified nanoparticles, 2-5 parts of anti-settling agent, 1-3 parts of leveling agent, 1-2 parts of defoaming agent, 5-10 parts of pigment and filler, and 20-40 parts of diluent; The epoxy resin composition is a composition of bisphenol A epoxy resin, epoxy block resin and modified epoxy resin, with a mass ratio of (60-70): (10-15): (10-15); The bisphenol A epoxy resin has an epoxy equivalent of 220-240 g / eq and a viscosity of 8000-12000 mPa·s at 25° C. The preparation method of the modified nanoparticles is specifically The following steps are involved: S1: Titanium dioxide and zinc nitrate hexahydrate are mixed and added to DMF, followed by glutaric anhydride and tetraisopropoxy titanate. The temperature is raised to 75-80°C and maintained for 2-2.5 hours. Ammonia water is then added to adjust the pH to 8-8.

5. Triethylamine, ethyl orthosilicate, and ethanol are then added. The mixture is heated to 60-65°C for 1.5-2 hours. After the reaction is complete, the product is filtered and washed to obtain pre-modified particles. S2: Add the pre-modified particles to DMF and mix evenly, then add 1,4-benzenedicarboxylic acid, stir at 50-60 rpm for 20-30 min until uniform, then heat to 80-90°C and keep warm for 1-1.5 h, then add dropwise the DMF solution containing 1,4-diaminobenzene for 1-1.5 h, after which the reaction vessel is heated uniformly to 110-130°C and kept warm for 14-16 h, and after the reaction is completed, naturally cool to room temperature and filter the product, wash with deionized water and acetone 2-3 times, and dry in a vacuum oven at 70-80°C to obtain the product; The mass ratio of titanium dioxide, zinc nitrate hexahydrate, glutaric anhydride and tetraisopropoxy titanate is (1.5-2): (4-5): (1.5-2): (0.2-0.4); The mass ratio of titanium dioxide, zinc nitrate hexahydrate, triethylamine and ethyl orthosilicate is (1.5-2): (4-5): (0.05-0.1): (0.4-0.5); The mass ratio of the pre-modified particles, 1,4-phthalic acid and 1,4-diaminobenzene is (3-4): (1.8-2.2): (0.6-0.8); The preparation method of the modified epoxy resin specifically includes the following steps: S1: adding a base epoxy resin to a reactor equipped with a stirring device, heating it to 80-90°C to completely melt it, then adding DMF and continuing to stir until it is evenly mixed; S2: slowly adding 4,4'-diaminodiphenyl ether while stirring at a speed of 80-100 rpm, and continuing to stir for 30-35 minutes after the addition is completed; S3: adding triethylamine, maintaining the temperature at 85-95°C, and continuing to stir and react for 2-4 hours. After the reaction is completed, stopping heating and allowing the mixture to cool naturally to room temperature, passing the obtained product through a 400-600 mesh sieve to remove unreacted solid particles and other impurities, and then transferring it to a clean container and storing it in a sealed container to avoid contact with air and moisture; The mass ratio of the matrix epoxy resin, 4,4'-diaminodiphenyl ether and triethylamine is (60-70): (10-20): (0.5-1); The mass ratio of the epoxy resin composition, curing agent and modified nanoparticles is (85-95): (18-22): (20-24); The epoxy block resin is an ethylene oxide-propylene oxide block copolymer resin having a weight average molecular weight of 2000-4000 Da and an ethylene oxide block content of 30-35 wt%; The average particle size of the titanium dioxide is 10-15 nm, and the average particle size of the modified nanoparticles is 550-650 nm; The anti-settling agent is at least one of fumed silica, hydrogenated castor oil, organic bentonite and polyamide wax; The leveling agent is at least one of an organic silicon leveling agent, a polyacrylate leveling agent, a polyether modified silicone oil leveling agent and a polyester leveling agent; The diluent is a composition of xylene and ethylene glycol monobutyl ether, with a mass ratio of (5-6): (1.5-2.5).

2. A method for preparing the chemical-resistant epoxy resin coating according to claim 1, comprising the following steps: S1: Add the epoxy resin composition to a reactor equipped with a stirring device, heat to 80-90°C, and stir continuously at 80-120 rpm until it is completely melted and uniform. Slowly add the modified nanoparticles, anti-settling agent, leveling agent, and defoaming agent while stirring, and continue stirring for 30-40 minutes to ensure that all solid particles are fully dispersed; S2: After adding pigments and fillers, stir at a high speed of 400-600 rpm for 60-80 minutes; S3: Cool to room temperature, slowly add curing agent, and continue stirring for 20-30 minutes. Finally, add diluent to mix the coating. After completion, pass through a 400-600 mesh sieve, and fill the obtained product into a container and seal it for storage.

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