A Winning Combination - The mineral part of the equation

Organosilanes rely on the reaction with surface hydroxyl groups to produce a stable covalent bond and a stable layer on the filler surface. They are, thus, most effective on fillers with high concentrations of reactive hydroxyls and a sufficient amount of residual surface water. Silica, silicates (including glass), oxides, and hydroxides are most reactive towards silanes. Silanes are generally not as effective on materials such as sulphates and carbonates. These can be encapsulated with silica and further modified with Dynasylan^®. Such layers are very complex and depend on the nature of the coating conditions, the type of the mineral surface, and the chemistry of the reactive functionalities present.

Dynasylan^® 9896 Improves Compatibility

This biggest market for mineral fillers is the mineral-filled plastics market. For this type of application, the virgin, untreated mineral has to be surface modified in order to be compatible with the polymer matrix. For some applications, surface modifiers are used that do not bond to the mineral surface and therefore show disadvantages in the final application. For example, silicone-oil-modified minerals in a plastic compound prevent the finished good, for example, plastic bags, from being printed. Therefore Dynasylan^® silanes are used in high-end and standard applications to improve process conditions and product properties. Equally as important as the performance is the increased understanding of environmental effects.

Our Dynasylan^® 9896 provides the ideal combination of low VOC and of a hydrophobic treatment of minerals for unpolar plastic applications, for example, PVC and polyolefins. For the concept to be proven, the viscosity of paraffin oil dispersions with untreated and treated titania was examined. A treatment with 1% Dynasylan^® 9896 reduces viscosity best.

The relevance of this test system towards practical conditions is:

• higher filler loadings
• improved processability
• less VOC, VOC < 100g/l