Poor adhesion problem
(1) The processing procedures of each stage of the pre-treatment are indeed in accordance with the prescribed inspection points and the inspection points requirements that must be met (the coated objects must not leave oil stains, moisture, impurities, release agents, etc.).
(2) Increase the baking temperature (coating bridging reaction temperature, subject to the heating temperature of the coated object. Non-set hot air temperature).
(3) Extend the baking time (the baking time and temperature of the coating must meet the basic requirements of the coating. If the temperature is reached but the time is insufficient, the hardness of the coating film will be insufficient, and the physical and chemical properties of the coating film will be relatively affected. influences).
(4) According to the substrate and required performance of the object to be coated, select suitable coatings.
1. If the drying condition does not reach the basic bridging reaction temperature of the paint, the film hardness, checkerboard size, and hardness may sometimes pass the test, but the chemical properties may not pass the test, so special attention must be paid.
The coating will change color
1. Select suitable pigments for this product according to the characteristics of the resin, the field of use and the warranty period.
2. According to the customer's purpose, performance requirements, warranty period, etc., provide coatings that meet the needs.
3. Paints containing lead, copper, and silver powder pigments must be painted with a top coat (clear paint) to prevent oxidation and discoloration.
4. Avoid staining the surface of the coating film with cement, white ash, chemicals (containing acid and alkaline substances). If it is unavoidable due to construction needs, it should be removed in the shortest time.
5. Strictly control the baking temperature and baking time.
Oil points Shrinkage cavities Depression pits (the surface of the coating has craters, bumps, and repulsion phenomena)
1. Strengthen the requirements for cleanliness and drying conditions of pre-treatment.
2. Strengthen the isolation of the painting work environment. The positive and negative air pressure should be adjusted appropriately. The filter of positive pressure (supply outlet) air needs to be replaced and cleaned regularly. People entering and exiting should avoid bringing food, oily skin care products, strong acids, strong alkalis and other items.
3. The repair and maintenance of automatic coating equipment must be implemented to avoid oil leakage due to malfunctions.
4. The maintenance of air compressors must be reliable, and related supporting equipment such as freeze dryers, air filters, water and oil filters, etc. must be regularly inspected and maintained, and their use timeliness should be regularly replaced.
5. The storage environment of the paint must be cleaned of unclean materials on the packaging barrel before unpacking and use to avoid contamination of the paint.
6. The temperature of the coated object is too high or too low, which will cause uneven surface tension (ductility) of the coating film.
7. For the combination of paint and solvent, the solubility, boiling point, drying speed, volatilization speed, etc. should be selected, which can meet the best conditions for film formation.
8. The viscosity of the paint should be adjusted appropriately when spraying.
9. Choose a suitable primer for use.
1. The surface of the object to be coated or the paint contains oil, water, debris, release agent and other pollution, the fluidity of the paint or the pits caused by the difference in surface tension between the primer and the top coat.
2. Avoid using spray insecticides, fragrances, wax sprays within the working environment, and pay attention to whether there are plastic injection factories or gas packaging factories nearby.
3. Excessive or unsuitable (such as silicone) defoamer or defoamer added in the pre-treatment degreasing tank will also cause it if the tank cannot be completely cleaned in clean water. Repulsion is more likely to occur in coatings with high resin content.
Orange peel (the coating film has bumps and bumps in the orange peel, and the entire coating film is wavy)
1. Adjust the paint spray viscosity to the appropriate number of seconds (measured with a measuring instrument, such as Simple Ford # 4 cups or Iwata # 2 cups).
2. Poor smoothness is due to uneven paint leveling and volatilization, resulting in uneven surface. Choose a suitable thinner according to the equipment and operating conditions.
3. The temperature of the coated object at the spraying point is preferably 50±5℃. Avoid temperatures above 60°C or below 10°C.
4. Spray the appropriate film thickness and uniformity.
5. Choose suitable spray tools (nozzle aperture is too large or too small) and proper adjustment and normal cleaning and maintenance.
6. Spraying technicians need to make appropriate corrections in spraying gestures for the different shapes of the objects to be coated, the size of the coating area, etc.
7. Ask the spraying technician to make appropriate adjustments to the spraying air pressure, paint output, running speed, and the distance between the spray gun and the surface to be sprayed.
8. Increase the temperature of the object to be coated or adjust the temperature of the coating appropriately.
1. The flatness of the coating film of the primer is not good.
2. Improper or unsuitable combination of primer and upper paint.
There is re-adhesiveness There is indentation (the surface of the coating film after baking, the phenomenon of re-adhesive w
1. Control the coating baking temperature (not the set hot air temperature; the bridging temperature of the coating is subject to the heating temperature of the object to be coated).
2. Control the appropriate baking time (the baking time and temperature of the paint must meet the basic conditions for paint bridging).
3. Choose the appropriate thinner to be used together.
4. The pre-processing procedures should be inspected according to regulations, and all control points must meet the inspection requirements.
5. Control the temperature and humidity of the working environment within the permitted conditions.
6. Review the best conditions for paint ratio.
Whitening (white turbidity of the coating film)
1. Avoid construction in rainy days or high humidity environments.
2. Oil-based or epoxy-based paints are slow to dry, so it is best to avoid applying them in the evening or night.
3. Perform construction after the temperature of the coated object rises.