Testing of film resistance to neutral salt spray

Determination of paint film resistance to neutral salt spray (GB/T1771-91) This standard applies to the determination of paint film resistance to salt calculation. The salt spray Test Chamber is used to control a certain temperature, salt water concentration and time for the test, and the grade is evaluated by the degree of damage to the appearance of the model.

(1) Materials and equipment

Refined table salt, steamed tobacco water.

Precision pH test paper: pH6.1~7.5.

Triangular beaker: l50mL

Glass funnel: diameter 100mm

Balance: Sensitivity is 0.001g.

The nozzle-type salt spray box controls the salt spray settlement to 0.4~1g/(80c㎡·h)

(2) Measurement method

Prepare 3.5% saline solution with distilled water and adjust the pH value to 6.5-7.2.

According to the product standard, select the base material and the supporting primer, and make the board with the technique of "Paint Film Preparation Method for Determination of Humidity and Heat Resistance, Salt Spray Resistance and Weather Resistance (Artificial Acceleration)" (GB/T1765).

The original state of the sample meal was recorded before the test.

The longitudinal direction of the sample plate is 30° to the direction of salt spray settlement, and there is a certain gap between two adjacent sample plates, and the row spacing is not less than 7.5cm.

Start the equipment, when the temperature in the box reaches 40°C±2°C, start to calculate the test time, spray every 45 minutes for the 15th minute, when not spraying, the relative humidity in the box needs to be kept above 90%, and the test lasts for 48 hours. Check once. After two checks, check once every 72 hours. After each check, the position of the sample should be changed. Perform a final inspection at the number of hours specified by the product standard. The inspection time of meta-product standards can be determined according to specific circumstances.

In the continuous test, it is necessary to check the nozzle frequently to keep the spraying normal. Salt water cannot be recycled.

(3) Sample inspection and rating

When inspecting, carefully take out the model. Rinse off the salt deposited on the model surface with tap water, quickly dry it with cold air (or dry it with a towel or aluminum paper), and carry out according to the "Paint Breaking Humidity and Heat Resistance Method" (GB/T1740) Check, rate.