Rapid detection method for mildew-proof durability of building mildew-proof coating

Abstract

The invention discloses a rapid detection method for mildew-proof durability of a building mildew-proof coating, and belongs to the technical field of coating detection. The method comprises the following steps: preparing a coating test plate and measuring the initial content a0 of a target mildew preventive in the coating test plate; placing the test panel in a high-temperature and high-humidity environment for accelerated aging; measuring the residual content a1 of the target mildew preventive in the aged coating; calculating the retention rate R of the mildew preventive according to the formula: R = (a1 / a0) * 100%; and according to a comparison result of the R value and a preset evaluation standard, rapidly obtaining the mildew-proof durability grade of the coating. According to the method, the loss rate of the effective components of the mildew preventive before and after simulated aging is quantified, a traditional mould culture observation method which is 28 days long is replaced, and the detection period is greatly shortened to 10-15 days from 35 days or above. The method is suitable for building mildew-proof coatings added with isothiazolinone mildew inhibitors, realizes rapid, quantitative and objective mildew-proof durability evaluation, and is suitable for mass rapid detection requirements in quality control and project acceptance.

Description

Technical Field

[0001] This invention belongs to the field of coating performance testing technology, specifically relating to a rapid testing method for the anti-mold durability of building anti-mold coatings, applicable to the performance testing of building anti-mold coatings with added isothiazolinone-type anti-mold agents. Background Technology

[0002] Anti-mold coatings for buildings inhibit mold growth by adding anti-mold agents, and their anti-mold durability is a key indicator of coating quality. Currently, the mainstream method in the industry for evaluating the anti-mold performance of coatings is based on GB / T 1741-2020, "Determination of Anti-mold Resistance of Paint Films." This method involves inoculating a test panel coated with the coating with a suspension of mixed mold spores, incubating it under constant temperature and humidity conditions for 28 days, and then rating the performance based on the area of ​​mold growth on the test panel surface. While this method provides intuitive and reliable results, it also has the following drawbacks: (1) The testing cycle is too long and cannot meet the needs of rapid evaluation: Traditional methods require at least 28 days of mold cultivation period. In addition, the time for test panel preparation, pretreatment and result observation is more than 35 days. This long cycle cannot meet the needs of rapid formula iteration in modern coating research and development, and it is also lagging behind the requirements of rapid acceptance of incoming materials by the engineering side, as well as the pace of production and engineering application.

[0003] (2) Lack of a quantitative and rapid evaluation system: Existing technologies mainly rely on the apparent mold growth for qualitative rating, which cannot provide quantitative indicators of mold resistance durability. Although existing technologies can detect the initial content of antifungal agents in liquid coatings through standards such as GB / T 37363.1-2019 and GB / T 37363.4-2020, these methods are only applicable to liquid coatings and cannot reflect the consumption of antifungal agents during the use of the coating, let alone establish a direct correlation between the residual amount of antifungal agents and the durability of mold resistance.

[0004] (3) The operation process is complicated and the results are unstable: Traditional mold culture test involves multiple steps such as test plate preparation, spore suspension preparation, inoculation, culture, observation and rating. Each step is affected by manual operation and environmental factors, resulting in large deviation of parallel samples, high difficulty in control, and poor consistency of test results between different laboratories.

[0005] (4) Low detection efficiency and difficulty in batch detection: Traditional mold culture tests require a large amount of constant temperature and humidity culture equipment, and the number of samples that can be detected in a single batch is limited, making it impossible to achieve high-throughput detection. This results in high cost and low efficiency for third-party testing institutions when conducting batch testing.

[0006] Isothiazolinone inhibitors are currently the most widely used class of antifungal agents in architectural antifungal coatings, including single varieties such as OIT, BIT, and DCOIT, as well as various compound systems. Their migration and loss characteristics within the coating are directly related to their antifungal performance. However, current technologies lack rapid and quantitative testing methods for the durability of antifungal properties in these coatings. Therefore, there is an urgent need to develop a rapid, accurate, and quantitative testing method to evaluate the durability of antifungal properties in architectural antifungal coatings, in order to address the aforementioned problems in existing technologies. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a rapid testing method for the durability of anti-mold coatings in building applications, thereby solving the problems of long testing cycles, qualitative results, cumbersome operations, low throughput, and inability to quantitatively predict durability in existing technologies.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention proposes a rapid testing method for the durability of anti-mold properties of building anti-mold coatings, comprising the following process steps: S1: Test panel preparation: The anti-mildew coating to be tested is evenly coated onto a standard test panel and cured to obtain a coated test panel; S2: Determination of initial content of antifungal agent: Take a portion of the coating test panels obtained in step S1 as control test panels and determine the initial content a0 of the target antifungal agent in the coating of the control test panels. S3: Accelerated aging test under damp heat: Place the remaining coating test plate obtained in step S1 in a damp heat simulation environment (such as a high and low temperature damp heat test chamber) for accelerated aging test; S4: Determination of antifungal agent content after aging: After the damp heat accelerated aging test in step S3 is completed, the residual content of the target antifungal agent a1 in the coated test panel after aging is determined; S5: Anti-mold durability evaluation: Based on a0 measured in step S2 and a1 measured in step S4, calculate the anti-mold agent retention rate R, R = (a1 / a0)×100%, and rate the anti-mold durability of the tested building anti-mold coating according to the pre-established correspondence between the anti-mold agent retention rate R and the anti-mold grade.

[0009] Furthermore, in step S3, the accelerated aging test temperature is set to 40±1℃, the relative humidity to 96±2%, and the duration of the accelerated aging test to be 7 to 28 days. These conditions simulate the actual environment of architectural coatings in the hot and humid regions of southern my country, accelerating the migration, hydrolysis, and loss of the antifungal agent through high temperature and humidity, thereby simulating the long-term use process.

[0010] Furthermore, the correlation between the retention rate R of the antifungal agent and the antifungal grade is as follows: When R ≥ 75%, the anti-mildew durability level is determined to be 0. When 60% ≤ R < 75%, the anti-mildew durability level is determined to be Level 1; When 40% ≤ R < 60%, the anti-mildew durability level is determined to be level 2; When 20%≤R<40%, the anti-mildew durability level is determined to be level 3; When R < 20%, the anti-mildew durability level is determined to be level 4.

[0011] Furthermore, in steps S2 and S4, the method for determining the content of the target antifungal agent in the coating is high-performance liquid chromatography (HPLC). Specifically, this includes: scraping the coating from the test plate, pulverizing it, sieving it, extracting it with an organic solvent, centrifuging and filtering the extract, and then injecting it into a liquid chromatograph for determination. The target antifungal agent is an isothiazolinone-based antifungal agent.

[0012] Furthermore, the isothiazolinone antifungal agent includes any one or more compound systems selected from 2-n-octyl-4-isothiazolin-3-one (OIT), 1,2-benzisothiazolin-3-one (BIT), and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT). When the target antifungal agent is OIT, the liquid chromatography conditions are as follows: a C18 reversed-phase column is used, the mobile phase is 0.02 mol / L ammonium acetate aqueous solution and methanol, gradient elution is used, and the detection wavelength is 275 nm. Furthermore, in step S1, the standard test plate is an aluminum alloy plate, and its surface treatment conforms to GB / T 9271. In step S1, a wire bar coater is used for coating, applying two coats. After the first coat is applied, it is cured for 6 hours before the second coat is applied. The standard test plate is an aluminum alloy plate with a surface treatment conforming to GB / T 9271, and the curing environment is a standard test environment with a temperature of 23±2℃ and a relative humidity of 50±5%, with a total curing time of 168 hours.

[0013] Furthermore, in step S3, the coating test panel is vertically suspended in a damp heat accelerated aging test chamber, with a spacing of not less than 20 mm between the test panels.

[0014] Furthermore, in step S4, before the test, the aged coating test panel is post-treated: the surface of the test panel is rinsed with running water to remove surface dust and exudates, the moisture is absorbed, and then placed under standard test conditions for 24 hours.

[0015] Furthermore, in step S5, if the relative deviation of the antifungal agent content determination results of the two parallel test panels is greater than 10%, the test is repeated. When the coating to be tested contains multiple target antifungal agents, the minimum value of the retention rate of each antifungal agent is taken as the comprehensive antifungal agent retention rate R for rating.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The testing cycle is greatly shortened: This invention accelerates the aging of the coating by using a high temperature and high humidity environment, transforming the traditional 28-day mold cultivation process into a controllable accelerated aging process of 10-15 days. Combined with the pretreatment time, the overall testing cycle can be shortened to 10-15 days, which significantly improves the testing efficiency and can meet the urgent needs of product development and acceptance.

[0017] (2) A quantitative rapid evaluation system was established: This invention innovatively uses the "retention rate" of the antifungal agent as the core evaluation indicator and establishes a quantitative correspondence model between the retention rate and the antifungal grade. By directly linking the retention rate (R) of the antifungal agent with the durability of antifungal properties, the transformation from qualitative rating to quantitative prediction is realized, providing a scientific basis for the performance evaluation of antifungal coatings. This method transforms the traditional qualitative rating that relies on manual visual inspection into a quantitative prediction based on chemical analysis, providing an objective and accurate scientific basis for the durability evaluation of antifungal coatings, and helping to accurately screen and optimize the performance of formulations.

[0018] (3) Simplified operation process and improved result stability: The method of this invention avoids the complex and easily contaminated steps involved in traditional mold culture methods, such as strain preservation, activation, and spore suspension preparation. It optimizes the sample pretreatment, detection, and evaluation process, and standardizes and simplifies the operation process. By strictly controlling the damp heat aging conditions and chemical analysis steps, this invention effectively reduces the errors introduced by human operation and environmental factors, significantly improves the consistency and repeatability of test results between different batches and different laboratories, reduces the difficulty of parallel sample deviation control, and improves the consistency of test results between different laboratories.

[0019] (4) Adaptable to batch testing and improved testing efficiency: The damp heat accelerated aging test is carried out in a standard high and low temperature damp heat test chamber, which can accommodate a large number of samples at a time, realizing high-throughput testing. At the same time, this method does not rely on special equipment such as mold incubators, nor does it require a lot of time for mold cultivation, which greatly reduces the time and equipment costs of testing. It is particularly suitable for batch testing by third-party testing institutions, large paint manufacturers, and government departments' supervision and spot checks, significantly reducing testing costs.

[0020] (5) Standardized testing process: Clarify the test operation process to ensure that the test results are accurate, reliable and repeatable, meet the standardization requirements of inspection work, and provide technical support for quality control of building anti-mildew coating production process, rapid screening of formula performance in product development stage, and acceptance inspection of building anti-mildew coatings upon arrival. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] Example 1

[0023] This embodiment provides a rapid testing method for the anti-mold durability of building anti-mold coatings (containing OIT anti-mold agent), the specific process of which is as follows: Step 1: Test plate preparation A 50mm×50mm×3mm aluminum alloy plate conforming to GB / T 3880.1 was selected as the standard test plate, and the surface was treated in accordance with GB / T9271.

[0024] The coating material to be tested was stirred thoroughly. A first coat was applied to the aluminum alloy plate using a 120 μm wire bar coater. After curing for 6 hours under standard test conditions (temperature 23±2℃, relative humidity 50±5%), a second coat was applied using an 80 μm wire bar coater. After coating, the test plate was cured under standard test conditions for 168 hours. A total of 8 parallel test plates were prepared.

[0025] Step 2: Determination of initial content of antifungal agent Take four cured test plates and carefully scrape the coating off the plates with a blade. Crush the scraped coating sample at room temperature and sieve it through a 0.5 mm stainless steel sieve. Accurately weigh approximately 1 g (accurate to 0.1 mg) of the crushed sample and place it in a 10 mL volumetric flask, then dilute to the mark with methanol. Vortex for 30 seconds to fully disperse the sample, then centrifuge at 12000 rpm for 15 minutes at 25 °C. Collect the supernatant, filter it through a 0.2 μm organic phase microporous membrane, and it is ready for analysis.

[0026] The content of OIT in the extract was determined by liquid chromatography. The liquid chromatography conditions were as follows: OIT determination: The chromatographic column was a C18 reversed-phase column (5.0 μm, 4.6 mm × 250 mm), the column temperature was 35 ℃, the injection volume was 20 μL, the mobile phase A was 0.02 mol / L ammonium acetate aqueous solution, the mobile phase B was methanol, the flow rate was 1.0 mL / min, and the detection wavelength was 275 nm.

[0027] The concentration of OIT in the sample solution was calculated based on a pre-established standard working curve. The initial OIT content in the coating was calculated using the formula a0 = (ρ × V × F) / m, where ρ is the mass concentration (μg / mL) read from the standard curve, V is the fixed volume (10 mL), F is the dilution factor of the test solution (1 here), and m is the sample mass (g). The arithmetic mean of the OIT content in the four test plates was calculated and used as the initial OIT content a0.

[0028] Step 3: Accelerated Aging Test under Humid Heat The remaining four cured test panels were vertically suspended in the high and low temperature humidity test chamber, ensuring a spacing of ≥20mm between the panels and that they did not contact the chamber walls or doors. The test chamber parameters were set as follows: temperature 40℃, relative humidity 96%. The test duration was set to 14 days.

[0029] Step 4: Determination of antifungal agent content after damp heat aging After the 14-day aging test, remove the test panels. First, rinse the surface of the test panels with running water for 1 minute to remove surface dust and any substances that may have precipitated, then blot dry with clean filter paper. Place the test panels under standard test conditions for 24 hours.

[0030] Following the same pretreatment and measurement methods as in step 2, the OIT content in the coating of these four aged test panels was measured. The arithmetic mean of the OIT content in the four test panels was calculated and taken as the residual OIT content a1 after aging.

[0031] Step 5: Evaluation of anti-mold durability: Calculate the retention rate of OIT: R = (a1 / a0) × 100%; The rating is based on a pre-established correspondence model: the R value measured in this embodiment is 2%. According to the model: R < 20%, the anti-mold durability level of the building anti-mold coating is determined to be level 4.

[0032] Example 2

[0033] This embodiment is basically the same as embodiment 1, except that steps 2-4 are replaced with a 28-day mold resistance test according to GB / T 1741-2020.

[0034] The R-value of the coating sample after 14 days of aging was found to be 2%. Based on the model, R < 20%, the anti-mold durability level was determined to be 4. Comparing this to the 28-day anti-mold resistance result (level 3) in GB / T 1741-2020, this demonstrates that the rapid experimental method in Example 1 can accurately predict its excellent anti-mold durability, shortening the testing time.

[0035] Effect verification

[0036] The retention rate R of the antifungal agent calculated after damp heat aging in Examples 1 and 2 of this invention was compared with the antifungal grade obtained by the 28-day mold culture method in the traditional process. The results showed a high negative correlation between the two: the higher the R value (the less antifungal agent is lost), the better the antifungal grade of the traditional method (the smaller the mold growth area, the smaller the grade number). This confirms the feasibility and scientific validity of rapidly and quantitatively predicting the long-term antifungal performance of the coating by measuring the retention rate R of the antifungal agent. Furthermore, the detection cycle of this invention (approximately 10-15 days to obtain the R value and predicted grade) is significantly shorter than that of the traditional process (>35 days to obtain the observation grade).

[0037] Potential applications of the process method of this invention include quality control in the production process of building anti-mildew coatings, rapid screening of formula performance during product development, acceptance inspection of anti-mildew coatings entering the construction site, rapid batch testing by third-party testing institutions, rapid initial screening on-site during random inspections of anti-mildew coating products, and rapid on-site evaluation of the anti-mildew performance of home decoration coatings.

[0038] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rapid testing method for the anti-mold durability of building anti-mold coatings, characterized in that, The process includes the following steps: S1: Test panel preparation: The anti-mildew coating to be tested is evenly coated onto a standard test panel and cured to obtain a coated test panel; S2: Determination of initial content of antifungal agent: Take a portion of the test panels from the coating test panels obtained in step S1 and determine the initial content a0 of the target antifungal agent in the coating of the test panels. S3: Accelerated aging test under damp heat: Place the remaining coating test plate obtained in step S1 in a damp heat simulation environment for accelerated aging test; S4: Determination of antifungal agent content after aging: After the damp heat accelerated aging test in step S3 is completed, the residual content of the target antifungal agent a1 in the coated test panel after aging is determined; S5: Anti-mildew durability evaluation: Based on a0 measured in step S2 and a1 measured in step S4, calculate the anti-mildew agent retention rate R, R=(a1 / a0)×100%, and rate the anti-mildew durability of the tested building anti-mildew coating according to the pre-established correspondence between the anti-mildew agent retention rate R and the anti-mildew grade.

2. The rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 1, characterized in that, In step S3, the test temperature for the accelerated aging test is set to 40±1℃, the relative humidity to be 96±2%, and the duration of the accelerated aging test to be 7 to 28 days.

3. The rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 1, characterized in that, The model relating the retention rate R of the antifungal agent to the antifungal grade is as follows: When R ≥ 75%, the anti-mildew durability level is determined to be 0. When 60% ≤ R < 75%, the anti-mildew durability level is determined to be Level 1; When 40% ≤ R < 60%, the anti-mildew durability level is determined to be level 2; When 20%≤R< 40%, the anti-mildew durability level is determined to be level 3; When R < 20%, the anti-mildew durability level is determined to be level 4.

4. The rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 1, characterized in that, In steps S2 and S4, the content of antifungal agent in the coating is determined by high performance liquid chromatography; the target antifungal agent is an isothiazolinone antifungal agent.

5. A rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 1, characterized in that, In steps S2 and S4, the pretreatment method for determining the content of antifungal agent is as follows: scrape the coating completely off the test plate, crush it at room temperature and pass it through a 0.5 mm metal sieve, accurately weigh the sample and make up to volume with methanol, shake to disperse and centrifuge, take the supernatant and filter it through an organic phase microporous filter membrane before testing.

6. The rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 4, characterized in that, The isothiazolinone antifungal agents include any one or more compound systems selected from 2-n-octyl-4-isothiazolin-3-one (OIT), 1,2-benzisothiazolin-3-one (BIT), and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT).

7. A rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 6, characterized in that, When the target antifungal agent is OIT, the high-performance liquid chromatography (HPLC) detection conditions are as follows: a C18 reversed-phase column is used, the mobile phase is a 0.02 mol / L ammonium acetate aqueous solution-methanol system, gradient elution is used, and the detection wavelength is 275 nm.

8. A rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 1, characterized in that, In step S1, a wire bar coater is used for two coats. After the first coat is applied, the coating is cured for 6 hours before the second coat is applied. The standard test plate is an aluminum alloy plate with a surface treatment conforming to GB / T 9271. The curing environment is a standard test environment with a temperature of 23±2℃ and a relative humidity of 50±5%, and the total curing time is 168 hours.

9. The rapid detection method according to claim 1, characterized in that, In step S3, the coating test plate is vertically suspended in a constant temperature and humidity environment with a spacing of not less than 20 mm between test plates, and the test plate does not contact the chamber wall or door of the environmental cavity; in step S4, before the test, the aged coating test plate is post-treated: the surface of the test plate is rinsed with running water to remove surface dust and exudates, the moisture is absorbed, and then placed under standard test conditions for 24 hours.

10. A rapid testing method for the anti-mold durability of building anti-mold coatings according to claim 1, characterized in that, In step S5, if the relative deviation of the antifungal agent content determination results of two parallel test plates is greater than 10%, the test is repeated; when the coating to be tested contains multiple target antifungal agents, the minimum value of the retention rate of each antifungal agent is taken as the comprehensive antifungal agent retention rate R for rating.