Film peeling defects and countermeasures

This is due to the poor adhesion or interlayer bonding of the coating film, resulting in partial or even complete peeling off.

(1) Improper pre-painting treatment, residual oil, water or release agent on the surface; or non-ferrous metals without proper surface treatment.

(2) The surface of the substrate is too smooth.

(3) The undercoat is left for too long, and the interval between recoating is too long; or the coating is overbaked, which affects its own adhesion and surface layer bonding.

(4) The surface of the old paint film is not polished and painted directly.

(5) The bottom and top coatings are not matched, resulting in poor bonding between layers.

(6) Scrape putty directly on the substrate without primer.

(7) The base coat contains silicone oil additives, which affect the wetting and bonding of the recoated paint film.

(8) Improper selection of pre-painted primers on non-ferrous metals and plastic surfaces.

The measures are as follows:

(1) Adopt suitable surface treatment before painting. Strengthen the degreasing effect; the phosphating film should be fine and thick; properly roughen the surface that is difficult to paint.

(2) Improve the construction process specification, grasp the coating process sequence and coating interval cycle, and it is not advisable to master the baking process conditions too well. For example, one spraying of ethylene peroxide coating should not be too thick, and it should be re-sprayed after the surface is fully dry. The wet coating is easy to peel off the whole sheet.

(3) Use a special pre-coated primer for special substrates. For example, the surface of aluminum alloy and galvanized sheet is primed with zinc yellow primer, tsi yellow primer or phosphating primer; the surface of modified polypropylene products is thinly sprayed with adhesion promoter (commonly known as plastic primer), Can effectively improve the coating adhesion.

The above are the defects that often occur in the construction process of coatings. During the use of coated products, the coating film will also have problems such as fading, powdering, blistering, cracking, brittleness, peeling, and rust. These problems are also affected by the construction operations during the painting process, but to a large extent, they are restricted by the quality of the paint, so we will not introduce them one by one here.