This
paper concentrates on a new kind of thixotrope, which is based originally on
organoclay chemistry, but spreads out the application areas to new grounds,
showing unique properties – the mixed mineral thixotropes – or, in short, MMTs.
In an organic surrounding, the hydrophilic parts of different platelets
interact with each other by hydrogen bonding. This gives a three-dimensional
network and creates the thickened gel structure, also called the card-house
effect (Figure 2). The gel has only a certain strength, which can be destroyed
by shear force and builds up again at low shear conditions (Figure 3). This is
always reversible. It gives the coating its thixotropic behaviour. Under no- or
low-shear conditions like storage and application sag, the viscosity is high
due to an intact gel. At brush or spray application the gel breaks down and
does not give much viscosity. This is why organoclays are used as anti-sag,
anti-sedimentation and anti-syneresis additives.