Why can't polyurethane paint be diluted with ordinary diluting agent?

One of the components of polyurethane paint is a compound containing isocyanate groups. When it meets compounds containing side groups, it will undergo a chemical reaction to form a high polymer. Ordinary thinners often contain water, so in the process of paint mixing and use, avoid contact with water, acids, alkalis, alcohols and other compounds, and do not use common thinners such as rosin, turpentine, alcohol, gasoline, etc. Gelling occurs, deterioration and scrapping.

Dilution needs to use the mixed solvent of anhydrous xylene, toluene and division and west class. Low boiling point solvents such as banana water and solvents with poor bases (such as alcohols) cannot be used. Thinners for polyurethane paints can be formulated in the following ways:

Proportion 1 anhydrous dimethyl:anhydrous cyclohexanone=1 : 1

Proportion 2 anhydrous xylene: anhydrous cyclohexidine: anhydrous butylacetate=7=2:1

The commercially available X-31 polyurethane lacquer thinner is made from xylene after calcium chloride water removal treatment, and is suitable for thinning polyurethane varnish, enamel, primer and polyurethane rubber enamel.