A coating accelerated weathering test method simulating hot and humid marine atmospheric environment

Abstract

The application provides a coating accelerated aging test method simulating a hot and humid marine atmospheric environment, and belongs to the technical field of coating performance evaluation.The coating accelerated aging test method comprises the following steps: S1, collecting environment data of an actual hot and humid marine atmospheric environment; and S2, performing a cycle test on a coating sample to be tested, each cycle comprising a light salt fog stage, a light drying stage and a salt fog stage.Through setting the cycle test comprising the light salt fog stage, the light drying stage and the salt fog stage, and reasonably setting test parameters according to the actual service environment, the characteristics of the actual service environment can be accurately reproduced, so that the characteristics of the hot and humid marine atmospheric environment can be more truly reflected, and the test results have better correlation with the hot and humid marine atmospheric environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coating performance evaluation, and particularly relates to a coating accelerated aging test method simulating a hot and humid marine atmosphere environment. BACKGROUND

[0002] As an efficient and economical protection method, coating is widely used in the protection of metal structural materials. However, the characteristics of high temperature, high humidity, high salt and high radiation in the hot and humid marine atmosphere environment can accelerate the aging process of the coating, and make the coating appear aging phenomena such as loss of luster, powdering and blistering, thereby reducing the protection performance of the coating. Therefore, it is crucial to accurately evaluate the aging behavior of the coating through accelerated test and reproduce the failure problems that may occur during the service of the coating.

[0003] At present, the indoor accelerated test methods for the corrosion aging behavior of the coating mostly adopt single-factor tests such as salt spray test and ultraviolet test, or carry out combined tests in combination with different single-factor tests. However, the existing test methods are quite different from the actual environment, such as the characteristics of the coupling type, coupling sequence and coupling time of the synergistic loading of factors such as light, salt mist, temperature and relative humidity in the actual environment, which causes the results obtained by the existing test methods to have poor correlation with the actual service environment, and the aging behavior and mechanism of the coating in the actual hot and humid marine atmosphere environment cannot be accurately reproduced.

[0004] Therefore, it is necessary to develop a coating accelerated aging test method which can simulate the coupling of light, salt mist, temperature and relative humidity in the actual hot and humid marine atmosphere environment, and has better correlation with the actual environment. SUMMARY

[0005] The present application aims to overcome the defect that the existing coating accelerated aging test has poor correlation with the actual service environment, and provides a coating accelerated aging test method simulating a hot and humid marine atmosphere environment. The coating accelerated aging test method comprises three test stages: a light and salt mist stage, a light drying stage and a salt mist stage. Each test stage is an independent cycle period, simulates the environmental characteristics such as dry-wet cycle, light change and multi-factor coupling existing in the actual environment, can more truly reflect the characteristics of the hot and humid marine atmosphere environment, and makes the test results have better correlation with outdoor natural exposure test.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A coating accelerated aging test method simulating a hot and humid marine atmosphere environment comprises the following steps:

[0008] S1. Collecting environmental data of an actual hot and humid marine atmosphere environment;

[0009] S2. Perform a cyclic test on the coating sample to be tested. Each cycle includes the following three test stages: light and salt spray stage, light drying stage, and salt spray stage.

[0010] The test conditions controlled during the light-induced salt spray stage are time, salt spray deposition, irradiation intensity, temperature, and relative humidity.

[0011] The test conditions controlled during the light drying stage are time, irradiation intensity, temperature, and relative humidity;

[0012] The test conditions controlled during the salt spray stage are time, salt spray deposition, temperature, and relative humidity.

[0013] The number of cycles in the accelerated aging test method of the present invention can be adjusted according to the differences in aging performance of different coatings.

[0014] Preferably, the duration of a single cycle is 24 hours, and the accelerated aging test method for the coating is performed for a total of at least 50 cycles.

[0015] In a single cycle, the time ratios of the light-salt-spray stage, the light-drying stage, and the salt-spray stage in the accelerated aging test method for coatings are determined based on the time ratios of the coupled effects of multiple factors such as light, salt spray, temperature, and relative humidity in the actual service environment.

[0016] For the four factors affecting corrosion aging—light, salt spray, temperature, and relative humidity—this study analyzes and statistically analyzes the coupling effects of these factors in the actual environment and their duration to determine the time proportion of the accelerated aging method. Assuming that salt spray is always present in the actual marine atmospheric environment, there are three coupling scenarios: The first is the coupling effect of light, salt spray, and high humidity, i.e., the environment has light, relatively high humidity, and salt spray, corresponding to the light-salt-spray stage in the accelerated aging test method for coatings; the second is the coupling effect of light, salt spray, and low humidity, i.e., the environment has light and very low relative humidity. In this stage, the main factor affecting aging is light, so salt spray is not applied, corresponding to the light-drying stage in the accelerated aging test method for coatings; the third is the absence of light, high relative humidity, and the presence of salt spray, corresponding to the salt-spray stage in the accelerated aging test method for coatings.

[0017] It should be noted that in this application, relative humidity RH ≥ 75% is considered high relative humidity, and relative humidity RH < 75% is considered low relative humidity.

[0018] Preferably, the irradiation intensity is set according to the following formula during the photo-irradiation salt spray stage and the photo-irradiation drying stage: Where E is the irradiance, and the unit is W / m². 2 H t The total amount of ultraviolet radiation during a specific period of illumination, expressed in MJ / m².2 ; t is the illumination time, in hours; α is the proportion of ultraviolet irradiance in the total irradiance of the irradiation source.

[0019] In the above formula, 277.78 is a constant, representing the conversion coefficient from MJ to Wh. Using this formula, and based on the total ultraviolet radiation and illumination time during a specific period in the actual service environment, combined with the ultraviolet irradiance ratio of the actual irradiation source used, a suitable accelerated test irradiance intensity can be calculated.

[0020] Preferably, the irradiation source is a metal halide lamp.

[0021] More preferably, the ultraviolet irradiance in the spectrum of the metal halide lamp accounts for 6-8% of the total radiation. Even more preferably, the ultraviolet irradiance in the spectrum of the metal halide lamp accounts for 6.8% of the total radiation.

[0022] Metal halide lamps have a spectrum closer to that of sunlight, which can better simulate the lighting characteristics of actual service environments.

[0023] Preferably, during the light-induced salt spray stage and the salt spray stage, the salt spray deposition rate is set to (1-2) ml / (80cm). 2 •h), using 5wt.% NaCl solution as salt spray.

[0024] Preferably, during the light-induced salt spray stage and the salt spray stage, the relative humidity is greater than or equal to the average relative humidity of the corresponding stage in the actual service environment.

[0025] Preferably, during the light drying stage, the relative humidity is less than or equal to the lowest relative humidity of the corresponding stage in the actual service environment.

[0026] More preferably, the relative humidity is 85-95% during the light-induced salt spray stage and the salt spray stage; and the relative humidity is 45-55% during the light-induced drying stage.

[0027] The light-induced salt spray stage and the salt spray stage are high-humidity stages, with the highest relative humidity in the marine atmosphere generally reaching over 90%. To accelerate the testing process and ensure the formation of a liquid film on the surface of the coated sample (the critical humidity for NaCl solution to form a liquid film through hygroscopic absorption is 75%), the relative humidity during the light-induced salt spray stage and the salt spray stage is preferably 85-95%. The light-induced drying stage is a low-humidity stage; to maintain the dryness of the coating surface, a relative humidity of 45-55% is preferred.

[0028] Preferably, in the photo-irradiation salt spray stage, the photo-drying stage, and the salt spray stage, the temperature is the highest temperature of the corresponding stage in the actual service environment.

[0029] Preferably, in each cycle, the three test phases are in the following order: photo-salt spray phase, photo-drying phase, and salt spray phase. This cyclical sequence of photo-salt spray phase, photo-drying phase, and salt spray phase closely resembles the actual marine environmental changes, allowing for more accurate accelerated test results.

[0030] The test sample includes the coating and the substrate.

[0031] Optionally, the coating is at least one of an acrylic coating, an epoxy coating, and a polyurethane coating.

[0032] The substrate can be a conventional coating substrate in the art, and the type of substrate has little impact on the accelerated aging test of the coating.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] This invention develops an accelerated aging test method for coatings that simulates a humid and hot marine atmospheric environment. Based on the main factors affecting coating aging during actual service, and analyzing the coupling of different environmental factors that may exist in the actual environment, an indoor cyclic accelerated aging test method is developed. By setting up cyclic tests including light-induced salt spray, light-induced drying, and salt spray stages, and by reasonably setting test parameters according to the actual service environment, the characteristics of the actual service environment can be accurately reproduced, thus more realistically reflecting the characteristics of a humid and hot marine atmospheric environment, and making the test results more correlated with outdoor placement in a humid and hot marine atmospheric environment. Attached Figure Description

[0035] Figure 1 The capacitance change of the coating sample in Example 1 during accelerated aging test in a simulated humid and hot marine atmospheric environment;

[0036] Figure 2 The capacitance changes of the coating sample in Example 1 after being placed in a humid and hot marine atmospheric environment for different times;

[0037] Figure 3 The capacitance change of the coating sample in Example 2 during the accelerated aging test of the coating in a simulated humid and hot marine atmospheric environment;

[0038] Figure 4 The capacitance changes of the coating sample to be tested in Example 2 were observed after being placed in the hot and humid marine atmospheric environment of Lingao for different periods of time. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0040] Example 1

[0041] This embodiment provides a method for accelerated aging test of coatings in a simulated hot and humid marine atmospheric environment. The coating sample used is an acrylic coating with a carbon steel substrate, and the simulated hot and humid marine atmospheric environment is a certain place in Qionghai.

[0042] The accelerated aging test method for the coating in this embodiment includes the following steps:

[0043] Environmental monitoring data were collected from a certain area in Qionghai, as shown in Tables 1 to 4.

[0044] Table 1. Statistical data of ambient temperature and humidity in Qionghai within one day.

[0045]

[0046] Table 2. Statistics of ambient light data in Qionghai within one day.

[0047] Time 0:00-6:30 6:30-18:30 18:30-0:00 Light None Yes None

[0048] Table 3 Statistical Analysis of Environmental Characteristics in Qionghai

[0049] Environmental factor coupling Time Light + salt fog + humidity 3h Light + dryness 9h Salt fog + humidity 12

[0050] Table 4 Total UV radiation at different times of the day in Qionghai

[0051]

[0052] Based on environmental characteristics, the photo-irradiation salt spray phase corresponds to the actual environmental time periods of 6:30-9:00 and 18:00-18:30, totaling 3 hours; the photo-irradiation drying phase corresponds to the actual environmental time period of 9:00-18:00, totaling 9 hours. The ultraviolet irradiance in the spectrum of the metal halide lamps used in the equipment accounts for 6.8% of the total radiation. Therefore, according to the formula... Calculate the irradiance of the metal halide lamps during the light-induced salt spray stage and the light-induced drying stage, respectively.

[0053] Irradiation intensity during the light-damp salt spray stage Irradiation intensity during the light drying stage

[0054] Based on the above environmental characteristics analysis, the parameters for a single aging cycle test are set as follows:

[0055] The following tests were conducted sequentially: a light-induced salt spray test, a light-induced drying test, and a salt spray test.

[0056] Light-induced salt spray stage test: duration 3 hours, salt spray deposition rate set at (1-2) ml / 80cm 2 •h, irradiation intensity is 290W / m 2 The temperature is 30℃ and the relative humidity is 90±3%.

[0057] Photo-drying stage test: time 9h, irradiation intensity 740W / m 2 The temperature is 40℃ and the relative humidity is 50±3%.

[0058] Salt spray stage test: duration 12h, salt spray deposition rate set at (1-2) ml / 80cm 2 • h, temperature is 30℃, relative humidity is 90±3%;

[0059] A total of 60 cycles were performed.

[0060] The coating samples were retrieved and analyzed at different time points. Coating aging failure mainly involves internal aging damage, which weakens the coating's barrier effect against moisture and other media in the environment, allowing moisture to enter and causing changes in capacitance. Therefore, this embodiment characterizes the degree of coating aging by measuring changes in coating capacitance, in order to evaluate the correlation between accelerated aging tests of coatings in simulated humid and hot marine atmospheric environments and actual environmental aging.

[0061] Coated capacitor C c =εε0A / d, where A is the coating area, d is the coating thickness, ε0 is the vacuum dielectric constant, and ε is the coating dielectric constant. Figure 1 The capacitance change of the coating sample in Example 1 during an accelerated aging test in a simulated humid and hot marine atmospheric environment; Figure 2 The capacitance changes of the coating sample in Example 1 after being placed in a humid and hot marine atmospheric environment for different periods of time.

[0062] The comparison shows that in the early stage of the experiment, when the coating was placed in an accelerated aging test and a humid marine atmospheric environment, the coating's lnC value... c With t 0.5 The relationships between the two tests showed a strong linearity. In the later stages of the accelerated aging test, the coating capacitance ceased to change, indicating that the coating was already saturated with moisture, and the moisture had diffused into the substrate, rendering the coating ineffective. However, in the actual humid and hot marine environment, the coating had not yet failed due to the shorter exposure time. The test results demonstrate that water transport within the coating conforms to Fick's second law in both tests, indicating that the coatings exhibit the same failure process, thus verifying the relevance of the accelerated aging test method used in this embodiment.

[0063] Example 2

[0064] This embodiment provides a method for accelerated aging test of coatings in a simulated hot and humid marine atmospheric environment. The coating sample to be tested is an epoxy coating, the substrate is carbon steel, and the simulated hot and humid marine atmospheric environment is Lingao, Hainan.

[0065] The accelerated aging test method for the coating in this embodiment includes the following steps:

[0066] Environmental monitoring data were collected in Lingao, as shown in Tables 5 to 8.

[0067] Table 5. Statistical data of ambient temperature and humidity in Lingao within one day.

[0068]

[0069] Table 6. Statistics of ambient light data in Lingao within one day.

[0070] Time 0:00-6:30 6:30-18:30 18:30-0:00 Light None Yes None

[0071] Table 7 Statistical Analysis of Environmental Characteristics in Lingao

[0072] Environmental factor coupling Time Light + salt fog + humidity 2h Light + dryness 10h Salt fog + humidity 12

[0073] Table 8 Total UV radiation at different times of the day in Lingao

[0074]

[0075]

[0076] Based on environmental characteristics, the photo-irradiation salt spray phase corresponds to the actual environmental time periods of 6:30-8:00 and 18:00-18:30, totaling two hours. The photo-irradiation drying phase corresponds to the actual environmental time period of 8:00-18:00, totaling 10 hours. The ultraviolet irradiance in the spectrum of the metal halide lamps used in the equipment accounts for 6.8% of the total radiation. Therefore, according to the formula... Calculate the irradiance of the metal halide lamps during the light-induced salt spray stage and the light-induced drying stage, respectively.

[0077] Irradiation intensity during the light-damp salt spray stage Irradiation intensity during the light drying stage

[0078] Based on the above environmental characteristics analysis, the parameters for a single aging cycle test are set as follows:

[0079] Light-induced salt spray stage test: duration 2 hours, salt spray deposition rate set at (1-2) ml / 80cm. 2 •h, irradiation intensity is 78W / m 2 The temperature was 30℃ and the relative humidity was 90% ± 3%.

[0080] Photo-drying stage: duration 10 hours, irradiation intensity 396 W / m² 2 The temperature was 40℃ and the relative humidity was 50% ± 3%.

[0081] Salt spray stage: duration 12 hours, salt spray deposition rate set at (1-2) ml / 80cm. 2 • h, temperature is 30℃, relative humidity is 90%±3%;

[0082] A total of 60 cycles were performed.

[0083] The coating samples were retrieved and analyzed at different time points. Coating aging failure mainly involves internal aging damage, which weakens the coating's barrier effect against moisture and other media in the environment, allowing moisture to enter and causing changes in capacitance. Therefore, this embodiment characterizes the degree of coating aging by measuring changes in coating capacitance, in order to evaluate the correlation between accelerated aging tests of coatings in simulated humid and hot marine atmospheric environments and actual environmental aging.

[0084] Coated capacitor C c =εε0A / d, where A is the coating area, d is the coating thickness, ε0 is the vacuum dielectric constant, and ε is the coating dielectric constant. Figure 3 The capacitance change of the coating sample in Example 2 during the accelerated aging test of the coating in a simulated humid and hot marine atmospheric environment; Figure 4 The capacitance changes of the coating sample to be tested in Example 2 were observed after being placed in a humid and hot marine atmospheric environment for different periods of time.

[0085] The comparison shows that in the early stage of the experiment, when the coating was placed in an accelerated aging test and a humid marine atmospheric environment, the coating's lnC value... c With t 0.5 The relationships between the two tests showed a strong linearity. In the later stages of the accelerated aging test, the coating capacitance ceased to change, indicating that the coating was already saturated with moisture, and the moisture had diffused into the substrate, rendering the coating ineffective. However, in the actual humid and hot marine environment, the coating had not yet failed due to the shorter exposure time. The test results demonstrate that water transport within the coating conforms to Fick's second law in both tests, indicating that the coatings exhibit the same failure process, thus verifying the relevance of the accelerated aging test method used in this embodiment.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for accelerated aging testing of coatings in a simulated humid and hot marine atmospheric environment, characterized in that, Includes the following steps: S1. Collect environmental data on actual hot and humid marine atmospheric environments; S2. Perform a cyclic test on the coating sample to be tested. Each cycle consists of the following three test stages: light-salt spray stage, light-drying stage, and salt spray stage. The test conditions controlled during the light-induced salt spray stage are time, salt spray deposition, irradiation intensity, temperature, and relative humidity. The test conditions controlled during the light drying stage are time, irradiation intensity, temperature, and relative humidity; The test conditions controlled during the salt spray stage are time, salt spray deposition, temperature, and relative humidity.

2. The accelerated aging test method for coatings according to claim 1, characterized in that, Each cycle lasts 24 hours, and the accelerated aging test method for the coating is performed for at least 50 cycles.

3. The accelerated aging test method for coatings according to claim 1, characterized in that, During the photo-irradiation salt spray stage and the photo-irradiation drying stage, the irradiation intensity is set according to the following formula: Where E is the radiation intensity, in W / m² 2 ; H t The total amount of ultraviolet radiation during a specific period of illumination, expressed in MJ / m². 2 ; t represents the illumination time, measured in hours (h). It represents the proportion of ultraviolet irradiance to the total irradiance in the irradiated source.

4. The accelerated aging test method for coatings according to claim 3, characterized in that, The irradiation source is a metal halide lamp.

5. The accelerated aging test method for coatings according to claim 4, characterized in that, The ultraviolet radiation in the spectrum of the metal halide lamp accounts for 6-8% of the total radiation.

6. The accelerated aging test method for coatings according to claim 1, characterized in that, During the light-induced salt spray stage and the salt spray stage, the salt spray deposition rate is (1~2) ml / (80cm). 2 ·h).

7. The accelerated aging test method for coatings according to claim 1, characterized in that, During the light-induced salt spray stage and the salt spray stage, the relative humidity is greater than or equal to the average relative humidity of the corresponding stage in the actual service environment; during the light-induced drying stage, the relative humidity is less than or equal to the minimum relative humidity of the corresponding stage in the actual service environment.

8. The accelerated aging test method for coatings according to claim 1, characterized in that, In each cycle, the three test phases are performed in the following order: light-drying salt spray phase, light-drying phase, and salt spray phase.

9. The accelerated aging test method for coatings according to claim 1, characterized in that, The test coating sample includes a coating and a substrate; the coating is at least one of acrylic coating, epoxy coating, and polyurethane coating.

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