Although coating is also a chemical product, it is different from general chemical . Therefore, according to the coating product and application characteristics, the quality inspection has different characteristics compared with general chemical products.
(1) Coating film inspection is a key quality inspection of coating products, which is mainly reflected in the performance of . This is because the coating is a polymer colloid mixture composed of various raw materials, which is used as a supporting engineering material. Unlike general chemical products, the quality can be judged from their chemical composition. . The coating product is mainly to check the performance of the coating film formed by it as a material coated on the object. Therefore, when evaluating the quality of the coating product necessary to check not only the coating product itself, but also the performance of the coating film, and should be based on This is the main one. The focus of paint inspection is to detect the performance of the coating film, while the inspection of the state is mainly to inspect the consistency of product quality. Therefore, the film-forming process of coatings and the performance test after film-forming are the basis for quality evaluation of coating products and the main content of coating quality . The detection methods in this area have developed the most and the fastest.
(2) The quality inspection of paint products should include the inspection of construction performance. There are many kinds wide range of applications, and the same paint product can be used in different aspects. Each paint product can play its role of decoration and protection only after it is applied on the object to be painted by the construction department to form a continuous and firmly attached film. This requires that each coating needs to have good construction performance, otherwise it will not achieve the expected effect. Therefore, in
When carrying out the quality inspection of the coating, it is necessary to check its construction performance.
(3) The physical method should be the main method, and the chemical method should be used as a supplementary method to check the performance of the coating film. The physical method is also the main method of inspection, and the chemical composition of the coating film is rarely analyzed. It is not possible to completely judge its quality status based solely on chemical composition analysis, but to see whether it meets the required material properties . Therefore, the detection of coating properties is mostly based on physical inspection. In addition, in the inspection of physical properties , the result measured by one detection method is often a combination of several properties. For example, the bending test commonly used to measure flexibility reflects not only the flexibility, but also the hardness, Adhesion and extensibility.
(4) It is necessary to select the corresponding substrate and prepare the sample plate according to the requirements. When checking the performance of the coating film , it is necessary to prepare the sample plate according to the strict requirements in advance, otherwise the correct result will not be obtained . Therefore, in the quality standard of each paint product, the method of preparing its coating film model as one of the standard conditions for paint quality inspection. In order to imitate the actual conditions as best as possible , most of the paint performance tests are carried out on the corresponding substrates, so the choice of test substrates has a certain relationship with the test results, and more importantly, the preparation process and method of the test coating film on the substrate. Quality has a significant impact on test results.
(5) It is necessary to select a more suitable method among various test methods. After years of development , after a test item has developed a variety of test methods, some methods are still retained because of their unique characteristics, which forms the test method and instrument diversification. A variety of testing methods for paint products coexist, and different methods of the same test item are tested from different angles, and the results are often different. Therefore, when testing paint, a more appropriate method should be selected from multiple test methods for product performance .
(6) The evaluation of some test results is difficult. Although the test methods have been developed , they are expressed by the most quantitative values, but some test items are compared with the standard conditions, or by the degree of change, such as "no change" and "slight change". " etc. said that there are many interference factors when evaluating the results . In addition, the detection methods are not yet fully instrumented, and some of them are visually observed , which may easily cause subjective errors and increase the difficulty of evaluating the detection results. Therefore, some inspection items stipulate that three or more samples are used for testing at the same time, and the majority of the results are used as the final judgment.
(7) It is necessary to combine multiple indicators to balance the judgment of paint performance. The paint product has passed the test , and the final evaluation of the results is more comparable to similar products, but less comparable to products with different compositions. Since the testing items are multi-faceted, the final judgment needs to be comprehensively balanced with various indicators, and the comparison of a single indicator cannot explain the performance of the product.
