GB/T 5209-1985 Determination of water resistance of paints and varnishes - Immersion method

This standard is applicable to the determination of water resistance of paint films. Water resistance is a performance index to assess the damage caused by paint films in conditions similar to condensation. The method is an accelerated damage test method. GB/T 5209-1985 Determination of water resistance of paints and varnishes - Immersion method GB/T5209-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of water resistance
Paints and varnishes
Water immersion method
Paints and varnishes-Determination of resistance to water-water immersion methodGB5209-85
Approved and issued by the State Bureau of Standards
1985-07-16Approved and implemented on 1986-03-01This standard applies to the determination of water resistance of paint films. Water resistance is a performance index for assessing the damage results caused by paint films in conditions similar to condensation. The method is an accelerated destruction test method. This standard refers to the international standard ISO1521-1973 "Paints and varnishes-Determination of water resistance-Water immersion method".
1 Test equipment and instruments
1.1 Test equipment: All parts in contact with the test water should be made of inert materials. 1.1.1 Water tank: It should be of suitable size (suitable size is 700mm×400mm×400mm), equipped with a lid and a constant temperature heating system. At the same time, the flow rate and water temperature of the water at each point in the tank should be basically consistent, and it is advisable to maintain a certain liquid level. 1.1.2 Water stirring system: It can be stirred by passing oil-free compressed air (meaning that no oil stains should float on the water surface during the circulation process) or pump circulation. But no matter which stirring method is used, the purpose of fully stirring the entire tank water must be achieved. 1.1.3 Test plate support: Made of non-conductive material, it should be able to keep the test plate at an angle of 15 to 20° with the vertical direction. The test surface of the test plate is upward and parallel to the water flow direction. 1.2 Conductivity meter: The measurement range is 0 to 10°us/cm; the basic error is not more than 1.5%. 2 Sampling
Select representative samples of the tested products according to the provisions of GB3186--82 "Sampling of coating products". 3 Test plate
3.1 Materials and dimensions
Unless otherwise specified or agreed upon by both parties, the substrate shall be cold-rolled ordinary low-carbon steel plate in GB708-65 "Rolled thin steel plate varieties", with a size of 150mm×70mm×0.5～1.2mm. 3.2 Substrate treatment and coating
Unless otherwise specified, the substrate surface treatment and coating shall be carried out in accordance with the methods specified in GB1727--79 "General preparation method for paint film".
Note: ① The coating thickness may be implemented in accordance with the product standard or the relevant provisions of the supporting system of the tested product. ② Drying conditions and time may be implemented in accordance with the product standard or the relevant provisions of the supporting system of the tested product. 3.3 Coating of the back and edges of the test plate
The back and edges of the test plate shall be coated with high-quality protective coatings that do not contain zinc chromate or any other similar water-soluble materials. The coating shall have no effect on the test results. Edge sealing width 2-3mm. 3.4 Determination of film thickness
The dry film thickness shall be determined according to the method specified in GB 1764-79 "Determination of film thickness". 4 Test conditions
4.1 Water quality
The water quality before the test plate is colorless, clear and has a conductivity of less than 2us/cm. During the test, if the color changes, becomes turbid or the conductivity exceeds 20us/cm, the water should be changed immediately. The conductivity measurement temperature of water is 20±1℃. 4.2 Water temperature
The water temperature at each point in the tank should be maintained at 40±1℃ from beginning to end. 506
5 Test stepswwW.bzxz.Net
5.1 Immersion procedure
Add sufficient amount of deionized water that meets the requirements to the tank, keep three-quarters of the sample immersed in water, and then start circulating or ventilating the water in the tank. Adjust the water temperature to 40 ± 1 ° C and maintain this temperature throughout the test. Take samples to check the conductivity of the water in the tank, so that it is not greater than 2us/cme. Perform a pre-test inspection on the test panels that have been dried and placed as required and make records. Then place them on the test panel rack to keep at least 30mm between the test panels and at least 50mm from the bottom and wall of the tank. During the test, the position of the test panel in the tank should be constantly changed, and the time interval between the change of position should not exceed 3d. 5.2 Intermediate inspection
If it is required to conduct an intermediate inspection during the test cycle, the test panel should be taken out of the tank, the water marks should be dried with filter paper, and the damage phenomenon should be checked immediately, and then it should be put back into the tank immediately. The inspection should be carried out in accordance with the relevant documents. 5.3 Final inspection
At the end of the specified cycle, take the test panel out of the tank, dry the water marks with filter paper, and check the damage phenomenon. However, when checking the paint film for reduced adhesion, brittleness, discoloration, gloss loss, rust and other indicators after the test, the test panel should be moved to a constant temperature and constant room (temperature 25±1℃, relative humidity 60%~70%) and placed for 24 hours before inspection. Use a non-corrosive paint stripper to carefully remove a 150mm×30mm paint film on the surface of the test panel, expose the substrate and check the exposed metal corrosion phenomenon. For reference, the exposed part should be protected with a suitable transparent coating. 6 Test results
The following damage phenomena are recorded as test results: blistering, wrinkling, rust, gloss loss, discoloration, shedding, reduced adhesion and substrate rust after paint stripping. Damage within 8mm of the edge of the test panel and obvious damage caused by human factors are not included in the test results. 7 Test report
The test report shall include the following contents:
a. Model, name, batch and production date of the tested product;
b. Standard number and name of relevant national standards, professional standards and enterprise standards;
c. Any differences from the contents specified in this standard due to negotiation or other reasons;
d. Detailed record of the surface condition of each test plate before the test;
e. Detailed record of the test results;
f. Test date;
name of the tester.
"Appendix A
Preparation of deionized water
(reference)
Purified water refined by ion exchange resin is called deionized water or ion exchange water. Usually, strongly acidic cation exchange resin (such as domestic 731 resin) and strongly basic anion exchange resin (such as domestic 717 resin) are used. There are three methods for making pure water by ion exchange: the compound bed method, the mixed bed method and the combined method. The compound bed method is composed of a single bed of cation resin and a single bed of anion resin in series. It is simple to operate, economical and easy to regenerate, but the water purity is low, the conductivity is above 2μs/cm, and it is slightly alkaline (pH8~10); the mixed bed method is to mix cation exchange resin and anion exchange resin in equal proportions according to the total exchange capacity [one (mass ) cation resin and two parts (mass) of anion resin mixed) are loaded into an exchange column. This method occupies less space, has a high flow rate, has high water purity, can be operated intermittently, and is conducive to laboratory applications; the combined method of a single bed of cation resin plus a single bed of anion resin plus a mixed bed of cation and anion resins is a more reasonable system, which combines the advantages of the first two methods. The resulting water has high purity and stable quality, and the conductivity can reach below 0.1μs/cm, the pH value is 6.57, the silicon content in the water is less than 0.01rpm, and the metal impurity content is below 0.001ppm. A.1 Pretreatment of resin
Take 4kg of cation exchange resin and put it in a plastic basin. Rinse it repeatedly with tap water to remove pigments, water-soluble impurities and other debris until the water is clear and free of foam, and rinse with deionized water. Soak for 4 hours. Pour out the water, soak in industrial ethanol for 8 hours, wash off the ethanol with water, and then soak the resin in 5% hydrochloric acid solution (preferably to cover the resin) for 4 hours. Stir appropriately, then drain the hydrochloric acid solution, and wash repeatedly with deionized water until the pH is 3-4. Take 8kg of anion exchange resin and put it in a plastic basin, rinse it repeatedly with water, and soak it in deionized water for 4 hours, soak it in industrial ethanol for 8 hours, and then soak it in 5% sodium hydroxide aqueous solution for 4 hours. Stir appropriately, then drain the sodium hydroxide solution, and wash it repeatedly with deionized water until the pH is 8-9.
A.2 Water production
Put the treated resins into the clean exchange columns respectively (the mixed bed should make the anion and cation resins fully mixed), and after the water is passed through, it can be used when the outflow water meets the water quality requirements. A. 3 Regeneration of resin
A.3.1 Regeneration of multiple beds
Cation resin single bed: Inject 800ml of 5% hydrochloric acid solution (for 4kg resin) into the exchange column from the high-level water tank through the water inlet, control the flow rate so that it is completed in about 30 minutes, and then rinse with water until the pH value of the effluent reaches 3-4. Anion resin single bed: Inject 1500ml of 5% sodium hydroxide solution (for 8kg resin) into the exchange column from the high-level water tank through the water inlet, control the flow rate so that it is completed in about 1 hour, and then rinse with pure water or water flowing out of the cation resin single bed until the pH value of the effluent reaches 8-9.
A.3.2 Regeneration of mixed bed
A.3.2.1 Alkali washing
Put the water level in the mixed bed level with the resin. Inject 15000ml of 5% sodium hydroxide solution from the high-level water tank through the water inlet, and control the flow rate so that it is completely discharged in about 1 hour. A.3.2.2 Backwashing and stratification
Water is introduced from the outlet at the bottom of the column and flows out through the inlet at the top. The amount of water inlet is controlled to keep all the resins in motion without loss. Backwash for about 1 hour until the pH value of the effluent reaches 8-9. After backwashing, the anion resin and the cation resin are stratified due to their different specific gravities, with the anion resin on the top and the cation resin on the bottom. A.3.2.3 Acid washing
Water is released to the interface between the anion resin and the cation resin, and 8000ml of 5% hydrochloric acid solution is passed through the acid inlet on the side of the exchange column (located at the resin interface), and flows out from the outlet through the cation resin. The flow rate is controlled so that it is completed in about 30 minutes. Then water is passed through the acid inlet to rinse the cation resin until the pH value of the effluent reaches 3-4. It should be noted that the acid solution and the eluent should not exceed 508
resin interface, otherwise it will affect the anion resin. A.3.2.4 Mixing
Add water to the column so that the water level is about 20cm higher than the resin surface. Use a blower to press air from the bottom of the mixed bed and mix for 3 to 5 minutes to mix the anion and cation resins evenly. Then use water. A.3.2.5 Separate regeneration of anion and cation resins If there is no acid inlet on the exchange column, you can first use tap water to backwash the anion and cation resins to separate them, and then use a vacuum pump to draw the upper anion exchange resin into the regeneration column through a hose, and regenerate the cation and anion resins separately.
For smaller mixed beds, it is inconvenient to regenerate in the column because the column is small, so static regeneration can be carried out in a plastic basin. First, pour the resin into the plastic basin, drain the water, add 20% sodium chloride solution, soak the resin surface, stir, and separate the anion and cation resins. Then, regenerate the anion and cation resins with 5% sodium hydroxide solution and 5% hydrochloric acid solution respectively. Additional Notes:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the National Technical Committee for Standardization of Paints and Pigments. This standard was drafted by Working Group 3 of the Technical Committee for Standardization of Paint Inspection Methods. The main drafter of this standard is Hu Weibang.
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