fluorocarbon paint is composed of polyvinylidene fluoride resin, pigment, modifier, etc. In the actual production process, aluminum alloy profile coating will produce linear or lattice cracks similar to dry riverbed, which is called "big crack". The "big crack" of
aluminum profile is usually caused by insufficient solvent when the sprayed paint film melts during baking. The following conditions will aggravate this phenomenon:
, the temperature of the metal surface rises to high temperature for too long;
, the flash drying speed of the paint film before baking is relatively too fast;
3, profile too thick and paint film too thick;
4, too high pigment composition, such as white and other light colors.
The following preventive measures shall be observed
1. Primer should not be sprayed too thick, and dry film thickness is recommended to be 5-10um;
, primer should not flash dry too fast before spraying topcoat, otherwise aluminum alloy profiles will cause dry absorption of topcoat solvent, adding slow drying solvent can prolong the wetting time of primer film;
3, topcoat should not be too thick, it is recommended not to exceed 35um, volatilization should not be too fast. It is recommended to use slow drying solvent, ethylene glycol monobutyl ether or butyl carbitol. Generally, the drying time should not exceed 0.5 hours.
4. The process of heating the furnace temperature to the set temperature cannot be delayed. Too slow or cold spots can lead to "big cracks".
