Common problems and analysis of PU paint and PU color paste application

1. Obvious roller marks appear in the wall roller coating of PU paint
reason: 

1) Uneven thickness during brushing operation

2) Construction without wet connection

3) Compatibility issues

4) Insufficient amount of additives in PU paint

5) The amount of emulsion in PU paint is insufficient

6) The wall is not completed at one time

Solution: mainly for compatibility issues
1) Mechanical dispersion (paint) The color of the paint can be displayed under the condition of a certain mechanical force dispersion.
2) Add wetting agent (color paint) After adding wetting agent, the color will become much darker, the color difference of finger grinding will become smaller, and there will be no obvious brush marks after brushing the board.
3) Adjust the paint formulation (base paint) Change the wetting, dispersing and thickening system of the paint to solve the compatibility problem between the paint and the color paste.

2. There are obvious rain marks on the surface of the paint after the rain

reason:

1) The water resistance of the base paint is poor (the emulsion is too hydrophilic, the amount of wetting agent is too large or the amount of hydrophilic additive is too large)
2) The water content of the base material is too high or the ambient humidity is too high
3) Sealed primer, did not achieve the effect
4) The coating film is washed with water before it is completely dry
5) There are too many residual additives in the dark paint

Prevention method:

1) Use as little surfactant as possible, try to use silicone to reduce hygroscopicity.
2) Use fluorine-modified resins or additives to enhance water repellency and stain resistance.
3) Use emulsion with good water resistance.
4) The surface is painted with varnish.

3. After a period of time, the wall surface will fade obviously (flowering)

reason:
1) The emulsion content of the paint is low.
2) The water resistance of the coating is not good.
3) Improper selection of color paste.
4) If the paint film is pulverized in dark colors, the color will also become lighter.
5) Color migration (migration to the inside).
6) The drying rate is poor due to conditions such as the sun exposure temperature of the construction project.
7) The flatness is not enough, resulting in poor vision in the distance under the influence of gloss.

Solution:
1) Increase the emulsion content in the paint.
2) Choose color paste with good weather resistance.
3) Engineering condition control.

4. Unable to call out the desired color
reason:
1) The content of titanium dioxide is not suitable (colors with poor hiding power cannot be displayed).
2) Improper selection of color paste (some colors cannot be replaced by other color pastes).
3) Color migration.

Solution:
1) Select the coating with appropriate titanium dioxide content.

2) Choose PU color paste with good compatibility.