What are varnishes and solvent-free paints?
Solvent-free varnishes and paints are distinguished by this, that the solvents do not evaporate when they cure. The most commonly used binders are epoxy and polyurethane resins. These binders can be made as very short chain molecules, so that varnishes and paints containing them have sufficient liquidity for application, no need to add solvents. However, if their share is necessary for dilution, then reactive solvents are added, which do not evaporate during hardening, but they chemically bond to the binder. Because solvents do not evaporate from solvent-free varnishes and paints, and their binders are chemically cured, it is possible to obtain a thick layer using these materials. They are used to cover substrates that are subject to particularly high loads, e.g. industrial floors, etc..
Also varnishes and paints on unsaturated polyester resins are sometimes referred to as solvent-free, because the solvent does not evaporate in these too, but in the process of hardening it is chemically bonded by polymerization to the binder molecule.
What varnishes are considered particularly resistant to:
a) zasady?
b) kwasy?
a) Za szczególnie odporne na zasady uważa się lakiery zawierające jako spoiwo żywice epoksydowe lub chlorokauczuk. Also varnishes based on polyurethane and acrylic resins are very resistant to alkalis.
b) Za szczególnie odporne na kwasy uważa się lakiery zawierające jako spoiwo żywice poliuretanowe lub chlorokauczuk. The acid resistance of epoxy varnishes depends on the type of hardener. If polyisocyanate is used as the hardener, the acid resistance is very high; the acid resistance is still good even when using polyamines and polyamides. Generally, most of the varnishes are rather insensitive to acids.