There are three main factors that affect the drying speed of PU paint:
1. Hydroxyl-containing materials: the larger the molecular weight and the lower the hydroxyl value, the faster the drying.
2. Curing agent: TDI trimer is very fast drying.
3. Catalyst: Tertiary amines are also very efficient when used at low temperatures. It is recommended to use organotin varieties that do not crystallize in winter on the market.

    At present, there are probably several ways to solve the problem of fast drying of PU primer:

1. Adding an appropriate amount of nitrocellulose to the primer will cause yellowing, collapse, and poor fullness, and it requires strong solubility of thinner, which will increase the overall cost.

2. In the general curing agent, use appropriate amount of TDI trimer to improve the dryness, but the cost rises too much, and it is not well matched with the hydroxyl-containing materials, which will also cause the paint film to become brittle, crack, and gloss and fullness. decline.

3. Use high-efficiency driers to help dry

    The use characteristics of quick-drying modifier:

Do not exceed 4.5% of the amount of alkyd resin, otherwise excessive modification will cause colloidal gelation. In summer, the dosage can be lower, so as not to dry too fast and cause the paint film to dry out.

Modification takes time. The modified primer should be used after 24 hours in summer and 48 hours in winter.

When modifying, first dilute the alkyd resin with the strong solvent in the formula, the amount of strong solvent can be slightly more.

The viscosity of the system will increase after modification. To control the viscosity, it is necessary to control the solid content of the primer.

Amine driers and low-temperature indoor driers can be used to further adjust the drying performance.