PU paint construction in winter attentions:
I. construction environment
The construction environment temperature shall not be lower than 5 ℃, and the humidity shall not be higher than 80%.
When the indoor temperature is lower than 10 ℃, it is suggested to take appropriate heating measures to ensure the drying speed of PU paint without affecting the production efficiency.
II. Product selection
1. The products shall be selected according to the season. Generally, Pu paint is divided into summer use and winter use. On the label of the certificate of conformity (S) is summer use and (D) is winter use. If not, it means universal. Especially for PU top coat products, in autumn and winter, summer products shall not be used, otherwise the gloss may be hoarse;
2. The matching Pu curing agent must be used for PU paint, especially for PU primer, the curing agent with low solid content shall not be used at will, otherwise it will lead to insufficient curing, large residual odor, undercutting, sagging of paint film, inaccurate gloss or low hardness of finish paint, etc;
4. Solvent selection:
At 15 ℃ - 20 ℃, Pu standard diluent cj-001l or SR-71 is selected;
When the temperature is lower than 15 ℃, Pu winter diluent cj-003l or sr-73 is selected.
III. paint mixing
1. Due to the low temperature in winter, the reaction speed between Pu main paint and curing agent becomes slower. 10% more curing agent can be added on site to improve the hardness and adhesion of the next day, which will not affect the gloss of the top coat. The primer can dry faster.
2. In winter, the addition of curing agent for PU clear primer shall not exceed 20% at most, and that for white primer shall not exceed 10%. Do not add more curing agent at will to improve the drying speed, otherwise it is likely to crack, poor adhesion, brittle paint film, later whitening and other conditions.
3. After the preparation of Pu primer and finish coat, they shall be used up within 3-4 hours (except for white base, they shall be used up within 2 hours).
IV, others
1. For the base material with high oil content or moisture content, it is necessary to control the moisture content of the wood by 8-12%, then seal the base material, and use Pu oil-resistant sealing primer cj-104y to effectively prevent the white phenomenon of the paint film. For example, teak, acid branch and oil-bearing pine need special attention.
2. Common base material sealing: please use sr-201 or cj-104 sealing primer to ensure the sealing effect.
3. It is not recommended to use common primer as sealer to seal the substrate after diluting, otherwise, the sealing performance is not enough, which may cause the later paint film to sink, etc. Moreover, bulk curing agent can not be used at will to avoid affecting the gloss of the top coat, the smell of the paint film, the crosslinking density of the paint film is not enough, or the paint film is brittle, cracked, etc.; bulk diluent may cause the smell of the paint film to remain large, the gloss is not allowed, and affect the transparency of the paint film, etc.
4. If putty is used in the construction, it shall not be scratched and coated too thick, and it must be thoroughly polished after being completely dried, especially in the solid paint process, to prevent cracking and falling off.
5. One time thick coating is strictly prohibited during plane construction to prevent the film from fogging and the surface from drying.