Study on the guarantee measures of steel drum coating quality (5)

Study on the guarantee measures of steel drum coating quality (5)

7, poor drying

After painting, it is dried according to the drying specifications specified by the technology, but the film is not completely cured, the film is wet, the hardness is low or the surface is not dry, which is poor drying.

Causes:

(1) Residual water or oil on the surface of the steel drum.

(2) The compressed air used in spraying contains oil and water.

(3) The spray coating film is too thick.

(4), poor drying in the drying and drying room (poor ventilation), high humidity in the drying kiln, low temperature, insufficient drying time.

Improvements:

(1) Strengthen the treatment of the surface of the steel drum before painting to remove the sputum and moisture in the compressed air.

(2) Control the thickness of the spray coating film.

(3) Ensure that all technical conditions in the drying room are in good condition.

8, rust

Shortly after the coating of the steel drum, red silk appeared under the coating film or rust spots appeared through the coating film.

Causes:

(1) There is a problem in the treatment of the steel drum before painting. The surface quality of the steel drum is poor, and the steel drum itself has rust, and it has not been cleaned before the treatment.

(2) After the surface of the steel drum is coated, the coating film is incomplete. If there are defects such as pinholes, leaking coating and exposed bottom, the corrosion resistance of the coating film is poor.

(3) Damage to the coating film during stacking, high humidity and high temperature in storage.

Improvements:

(1) The surface of the steel drum must be cleaned before painting, and it is possible to perform phosphating.

(2) to ensure the integrity of the coating of the steel drum.

(3), do not damage the coating when stacking, can not roll on the site; warehouse should pay attention to ventilation, it is strictly prohibited to stack in the open air.

9, become brittle

The phenomenon that the coating film loses its elasticity or the elasticity is deteriorated is called brittleness, which is a prelude to cracking or peeling of the coating film.

Causes:

(1), superheat drying, that is, the flooding temperature is too high, and the drying time is too long to make the coating film become brittle.

(2), the paint expires, the poor coating film is also easy to become brittle.

(3) The coating film is used under too low temperature conditions.

Improvements:

(1) Drying according to the drying conditions recommended by the process regulations or technical conditions. If the drying chamber needs to be repaired for a long time due to failure, the temperature of the kiln in the drying chamber should be lowered or the dried steel drum should be taken out in time.

(2), use high-quality coating, pay attention to the expiration date of the coating.

(3) In the case of using steel drums under too low temperature conditions, it is necessary to use special coatings for coating.

10. Finishing method of coating film defects

According to the type and severity of the film defects and the degree of influence on the protective properties of the coating, the following three trimming processes are generally available.

(1) Under the premise that the flatness of the coating, the overall adhesion and the protective performance are not affected, the defects are small, and the range is not wide, the sanding paper is generally polished directly or manually, and the defects are manually refilled. This finishing process is suitable for exposed bottoms, poor coverage, and other minor defects in a small range.

(2) In the case where the defects are serious, affecting the flatness, integrity and overall protection performance of the coating, it is generally necessary to use sandpaper to carefully grind and other methods to eliminate the coating film defects. Then re-spray, and pay attention to timely measures to avoid similar defects.

(3) In the case where the defect is serious, the coating is incomplete, and the protective performance has been lost, such as severe pinhole, rust, brittleness, peeling cracking, etc., the original coating should be completely removed. Paint to make it a qualified product.