Binders and polyurethane resins

Both in the field of truck paint and in automotive finishing, solvent-based car paints can be found in the composition, which are based on a polyurethane resin formula "PU"

PU are two-component polymers : they use a hardener, which is added just before use. Separated, the two components cannot dry out or harden. Once mixed, a phenomenon of polymerization quickly occurs, which is a hardening of the dry film, without the aid of air or temperature. They are called 2C or 2K.

Characteristics of polyurethane paints

These paints are varnishes or finishing lacquers, shiny and very resistant, such as "direct gloss" paints or varnishes. A polyurethane lacquer has a fairly high viscosity and the hardening of polyurethane paints takes place quite slowly (24 hours at heart), and drips can occur in the event of excess.
Once dry, polyurethane paints form a film with a significant thickness of 50 microns. This film looks like a layer of plastic that is totally waterproof, resistant to chemicals, and resistant to temperatures of 250°C.

The disappearance of polyurethane paints in cars

“Direct gloss” lacquers are hardly used on cars anymore and even less on motorcycles. Only a few simple color codes recorded in the 1950s to 1980s still use the polyurethane formula. In question, modern automotive colors which are more complex.
Indeed, most modern colors contain mother-of-pearl and aluminum pigments, which do not support bi-component polyurethane lacquers: the particles tend to move and to slide during the long drying time, especially on the vertical surfaces of the bodywork.

The new polyurethane varnishes for bodywork

Recently, new formulations of hybrid acrylic polyurethane automotive clearcoats have appeared, offering exceptional performance. Resulting from technological developments, in particular from StardustColors, they bring clear progress for the varnishing of vehicles :
Firstly, accelerated drying speed (through-drying goes from 24 hours to 45 saves energy, as cooking is no longer necessary). For bodywork professionals, this means better rolling and the end of cab congestion, since the motorist can be driving as early as 45 minutes after the application of the varnish.
Secondly, higher solids levels high (more thickness, more solidity), and therefore lower levels of solvents released.

Epoxy resin binder
Nitrocellulose resin binder
Solvent-based acrylic resin binder
Car paint solvents
Additives adjuvants