BENTONE® P 380 MS

BENTONE® P 380 MS Pre-Activated Hectorite Clay-Based Rheology Modifiers for Non-Water-Based Paints and Coatings Systems BENTONE® organic clays are rheology additives used to achieve "high viscosities" with optimized anti-sedimentation at low shear rates. BENTONE® organic clays are either bentonite-based or hectorite-based. Both minerals belong to the smectite group and consist of micro-fine platelets stacked on top of one another. When these platelets are exposed to water, they swell due to their natural mineralogical structure. To make the platelets compatible with non-water-containing liquids (e.g. organic solvents), each individual platelet surface must be modified with quaternary ammonia compounds. The modification selection and process conditions chosen for each platelet have a strong influence on the suitability and performance of the platelet systems. After completion of the aforementioned ion exchange reactions, the resulting organic clay is dried and ground into powder. The rheological efficiency of the clay depends on the dimensions of the individual platelets. The smallest particle size is preferred since the edge length of the platelets is important for viscosity. Surface area plays a minor role in rheology control. Generally, the smaller a particle's size, the longer its edge length.

Hectorite clay consists of noticeably smaller particles compared to bentonite. Therefore, for a given quantity, its edge length is much longer. Due to this difference, hectorite can form a denser rheological network and significantly higher rheological efficiency is achieved in optimum applications.

Organic clays must be exposed to "high" shear forces for a certain period to be activated. As a result of this process, interconnected platelets first swell, then delaminate and separate. These activated platelets provide the desired viscosity through the effect of internal molecular forces (for example, the formation of hydrogen bonds in the aqueous portion of the chemical activator). Chemical or polar activators are mixtures of short-chain alcohols with water or special additives (for example, DAPRO FX 2060 and DAPRO BEZ 75). In systems where water cannot be tolerated, propylene carbonate is a suitable option. Small-sized hectorite-based rheology modifiers require noticeably higher shear forces compared to bentonite-based products to achieve the desired performance. For organic clays (particularly hectorite-based ones) to be fully activated, high-performance dispersers such as Cowles-type saw-tooth dissolver mixers are required. However, not all processing companies have these types of machines. With the new pre-activated BENTONE® organic clay pastes, the "activation process" described above is not necessary. The clay contained in BENTONE® products is pre-activated using Elementis proprietary special processes and is ready in various solvents.

With the new product BENTONE® P 380 MS, users obtain many advantages compared to powder product applications:

• Significant reduction in process time, • Reduction in the number of raw materials required due to elimination of polar/chemical activators, • Dust-free production, • No need for production stages requiring high process stability, • Direct addition of raw materials with gentle mixing. BENTONE® P 380 MS delivers noticeably higher performance compared to conventional powder organic clay pastes. The viscosity difference between BENTONE® 38 and BENTONE® P 380 MS is clearly visible in the graph below. The data in the graph shows that the viscosity obtained in alkyd-based coating systems using BENTONE® P 380 MS performs at noticeably higher levels at "low" and "medium" shear rates compared to conventional organic clays with pregelled addition. The data also shows us that other properties such as the "settling stability" of the coatings can be improved.

Currently, the use of pre-activated BENTONE® organic clay pastes with three different solvents is recommended:

• White spirit, aromatic-free => for low and medium polarity systems, • Isoparaffin, aromatic-free => for low and medium polarity systems, • Castor oil => for medium and high polarity systems. Dilşat Şahin Technical Director Fuchs