Typical features of PU lacquers
Another designation for PU lacquer is DD lacquer (named after the brand name of the first binder for hardener and lacquer resin: Desmodur/Desmophen). The ‘PU’ abbreviation stands for the description of the ‘plastic’ created during complete hardening: Polyurethane.
PU lacquers are universally usable surface materials. They are two-component systems. This means that, after the precise addition of a specified quantity of hardener, the lacquer-hardener mixture will only remain ready-for-use for a certain time period without sacrificing quality (= processing time). After that, the chemical reaction changes the mixture so significantly that it can no longer be used for coating without modifications. (The period of time from mixing the lacquer-hardener batch to this point is called the pot life.) The solids content varies from around 20 % to 70 % depending on the type of lacquer system used. This is still a relatively high solvent content.
PU lacquers are first dried physically by evaporation of the solvent and then chemically by polyaddition between resin and poly-isocyanate without any separation of by-products.
The dried and hardened lacquer film is solvent-fast and resistant to a number of chemical and mechanical influences. As a result, PU lacquers are suitable for heavily used surfaces such as kitchen, bathroom and office furniture as well as table tops.