In the painting of the outer surface of railway locomotives and rolling stock, topcoat Coating is a crucial part. It not only refreshes the vehicle Appearance, but also bears the responsibility of protecting the body surface from the external environment. However, in order to ensure the safety of the painting mass and the long-term use of the vehicle, a comprehensive inspection of the topcoat is necessary. Topcoat Coating usually consists of Resin, pigment, additives and solvents. According to the different requirements of use, topcoat Coating is divided into alkyd and polyester, and its product naming must comply with the corresponding standards (GB/T 2705).
Technical requirements
Topcoat products need to meet a series of technical requirements, including painting performance, weathering resistance, chemical resistance, etc. The specific requirements are detailed in standard table 1. At the same time, the intermediate coating and putty used with topcoat also have their own technical conditions.
Test method
In order to ensure the painting mass, the topcoat Coating needs to go through a series of tests. The environmental conditions of the test are carried out in accordance with GB/T 9278, and the film performance of the two-component Coating should be determined after drying for 7 days. The test methods include paint film Color and Appearance inspection, outflow time measurement, fineness measurement, hiding power measurement and other aspects. Each test needs to be operated according to the standard, especially for two-component Coating, the two components need to be mixed in the specified proportion and then measured. The following is a detailed detection method for topcoat Coating:
1. Color and Appearance inspection
Color and Appearance of coated surfaces under natural scattered rays of light. Visually inspect to determine color difference, uniformity, gloss, etc.
2. Measurement of outflow time
Use ISO No. 6 Flow Cup and measure the outflow time according to GB/T 6753.4. For two-component Coating, the two components should be mixed in the specified ratio for determination.
3. Fineness determination
According to GB/T 6753.1, use a Fineness Meter for fineness determination. For two-component Coating, the two components need to be mixed in the specified ratio for determination.
4. Measurement of hiding power
Measurement of hiding power according to GB/T 1726. For two-component Coating, the two components should be mixed in the specified proportion for determination.
5. Determination of Coating Life of Two Groups
The two components of Coating were mixed according to the specified ratio, a total of 200 g, modulated to the applicable viscosity, and the time of livering was determined.
6. Determination of surface drying time and hard drying time
The determination of surface drying time is carried out by method A in the surface drying time determination method in accordance with GB/T 1728. The determination of hard drying time is also carried out by method B in the actual drying time determination method in accordance with GB/T 1728.
7. Measurement of construction performance
Preparative paint film samples are prepared according to 1.5 times the thickness of each dry-film required by the buyer. Observe the dried paint film to ensure that there is no obvious sag, blistering, wrinkling, orange peel, pinholing and other adverse phenomena.
8. Bending performance test
Bending performance tests are carried out according to GB/T 6742 to determine the flexibility of the film.
9. Cupping test and cross-cut test
Cupping tests and cross-cut tests are performed in accordance with GB/T 9753 and GB/T 9286 to evaluate the film's endurance and abrasion resistance.
10. Measurement of impact resistance
Impact resistance was determined according to GB/T 1732 to determine the impact performance of the film.
11. Gloss, hardness, water resistance, etc
Including Gloss, hardness, water resistance and other indicators of the determination, in accordance with the corresponding standards.
12. Determination of chemical resistance
Including the determination of gasoline resistance, acid and alkaline resistance indicators, according to GB/T 1734 and Miscellaneous related standards.
13. Accelerated test of heat resistance and artificial climate resistance
According to GBT 1735 and GB/T 14522 heat resistance and artificial climate accelerated test to evaluate the film durability and weathering resistance.
According to the provisions of HG/T 2458, the inspection of Coating products should be carried out according to the standard operation. Routine inspection should be carried out when each batch of products leaves the factory, and type inspection should be carried out once a year. When the user department accepts the Coating products, it is also necessary to carry out acceptance inspection in accordance with the provisions of this standard to ensure that the product mass meets the requirements. Encasement, Encasement mark, storage and transportation of Coating products should comply with the corresponding standards (GB/T 13491, GB/T 9750, HG/T 2458). In addition, different types of Coating products have different effective shelf life, solvent-based paints for 1 year, water-based paints for half a year, and two-component putty for half a year.
Through the above detection methods, the mass of the topcoat for railway locomotives and rolling stock can be guaranteed to ensure that the outer surface painting of the vehicle achieves the expected effect and has long-term safety. Strict testing and management of Coating products is not only an important measure to ensure the safety of railway transportation, but also a manifestation of responsibility for passengers and goods.
