Лако-красочные материалы — производство

The non-volatile content (nvc), or solids as it commonly referred to, is a standard test method in resin chemistry, but there are a multitude of different methods depending upon the volatility of the solvent/water, etc., and thermal stability of the resin. Acrylamide containing resins slowly decompose on heating, and it is generally difficult, if not impossible, to obtain a non volatile content to constant weight.

A common fault in determining non volatile contents of latices is to use too thick a sample. Not more than lg of emulsion should be used in each tray, and in the case of viscous emulsions, the sample should be quickly spread with a small spatula before weighing. Drying should be for 30 minutes at 130°C.

The time and temperature can be altered if it is consistently found that constant weight is not being achieved. Vacuum ovens can be used for thermally sensitive polymers. For some systems it is desirable to move the resin during evaporation of water/solvent and a bent paper clip, pre-weighed into the ‘solids dish’ can be used to stir the ’drying film’ to avoid a crust forming entrapping liquid underneath. As a general rule, this technique is more important for the faster evaporating organic solvents.