Dynasylan® XAR is a pre-hydrolyzed, ready-for-use silicic acid ester – hybrid binder with additional colloidal SiO2 particles. Dynasylan® X15 contains a mixture of ethanol and isopropanol as solvents and sulfuric acid as catalyst.
Scope of Application
Dynasylan® XAR is especially suited for use in: ceramic casting molds, methods: precision casting (lost wax or casting shell methods) and ceramic molding (ceramic form or SHAW molding processes). Refractory materials 2-pack zinc dust anti-corrosion paints, (e.g. shop-primers) Dynasylan® XAR in conjunction with especially refractory forming materials results in ceramic casting molds that have highly precise surfaces and dimensions. In zinc rich paints with a zinc content above 95 % Dynasylan® XAR binds the zinc and allows for the formation of hard coatings with an effective galvanic protection. The storage stability of Dynasylan® XAR is 6 months. It is determined by the degree of partial hydrolysis and the pH value. Nonetheless, the condensation and hydrolyzation proceeds during storage, as these reactions have not been suppressed, only reduced. The further the hydrolysis has proceeded the faster the condensation (and thus gelation) occurs when the product is used. This means, that the reactivity depends on the age of the binder which needs to be considered during use. The reactivity of the slurries and 2-pack zinc dust paints depend on the age of the binder. Dynasylan® XAR can be used as delivered to make ceramic slips, immersion/ramming mixes, and 2-pack zinc dust anti-corrosion paints. The degree of hydrolysis and acidity have been optimized for the required reactivity and sufficient storage stability. Through the addition of alcohol and/or water it is possible to vary the SiO2-content and the curing properties. The hydrolysis and condensation has been started during the production of the binder. Through a shift in the pH-value this process is accelerated. This shift is achieved by addition of fillers, pigments, additives, or through the evaporation of solvent or exposure to atmospheric moisture. The resulting silicic acid gel cures rapidly at ambient temperatures in air. The process of curing can be accelerated through the addition of alkali catalysts. Zinc dust paints on the basis of Dynasylan® XAR cure rapidly under ambient moisture. Temperature and humidity are important for the curing process. By proper application and formulation, zinc dust paints on the basis of Dynasylan® XAR can yield excellent corrosion protection.