Construction technology of waterborne coating

Storage of water-based coating base material shall be stored at 5-25 ℃. The tank cover shall be closed immediately after opening the tank for use to prevent scaling. The storage life of unopened coating shall be within 6 months, and the storage life shall be reduced by half after opening. The coating curing agent shall be stored at 5-25 ℃. The tank cap shall be closed immediately after the tank is opened for use. Before closing the bottle cap, the residual curing agent at the bottle mouth shall be wiped to prevent the bottle mouth from being sealed due to the reaction between the curing agent and moisture in the air. The storage life of the unopened curing agent shall be within 3 months. It shall be used as soon as possible after opening.

The surface of construction preparation plate shall be cleaned with alcohol to ensure no solvent or oil residue. The spraying equipment shall be cleaned as follows: the hydrophilic solvent is generally industrial alcohol. If the coating in the equipment is placed for a long time and the alcohol cleaning is not clean, acetone cleaning can be considered. If the water-based coating is sprayed and then sprayed, it shall be cleaned with deionized water first, then with hydrophilic solvent and then with deionized water after Z. Preparation process of coating: after the tank is opened, the coating base material needs to be stirred evenly with a mixer to ensure that there is no scaling and sedimentation.

In the stirring environment where the vortex is formed in the middle, add the curing agent slowly, stir at a constant speed for about 2 minutes, and then add an appropriate amount of deionized water for dilution. Since the service life of the water-based coating curing agent after mixing is within half an hour, it needs to be sprayed as soon as possible to prevent the viscosity from increasing and it cannot be sprayed. After spraying, it also needs to be cleaned as soon as possible to prevent blocking the pipeline after agglomeration. Construction process of coating after mixing, 100 mesh filter screen shall be used for filtering before spraying, and after filtering, it shall be sprayed in a closed tank. During spraying, the ambient temperature shall be kept at 20-30 ℃, the humidity shall be 55-70%, and the dry film thickness shall be 25-35um. After spraying, it shall be flash dried for 10-15 minutes, and then baked at 75-85 ℃ for 25-35 minutes.

Precautions: the curing agent shall be used as soon as possible after it is opened. In case of swelling, the curing agent has become invalid. The water-based coating is highly sensitive to oil contamination, so it is necessary to keep the spraying equipment, template and environment clean. Otherwise, it will cause shrinkage, particle and blooming. During cleaning, ensure that the two diluents before and after are miscible, such as water and clean water solvent, hydrophilic solvent and solvent diluent. Try to ensure the airtightness of the coating during preparation and spraying. The amount of deionized water in the coating depends on the actual situation. The spraying viscosity will be higher than that of solvent based coating. If the spraying viscosity is too small, there will be sagging and back thick edges. If the viscosity is too large, there will be orange peel. Due to the slow evaporation rate of water, too much environmental humidity, too thick film thickness, too short flash drying time, too high baking temperature, etc., various defects of the paint film formed due to the failure of water to volatilize completely, such as pinholes, bubbles, loss of gloss, etc.