HIFULL Fumed SILICA– Rheological Additives for Adhesives & Sealants
In sealants and adhesives, fumed silica plays a major role in rheological control and viscosity strength.When fumed silica is added and dispersed in adhesives and sealants, a silica agglomerates network is formed, agglomerates react with SI-OH and result in hydrogen bonds, thus flowing property is restricted and viscosity increased, thickening property promoted; but,when shear thinning is applied, hydrogen bonds and silica network breaks,viscosity decreases, this allows adhesives and sealants to be applied smoothly; when shear thinning is removed, network restored,viscosity increases, this prevents adhesives and sealants from sagging during curing process.
What functions fumed silica brings for Adhesives & Sealants?
*To be applied smoothly when being sprayed or under high mechanical stress;
*Keep high viscosity during storage or transport or when it’s adheres to the substrate;
*Tailored viscosity available according to requirements of different applications;
*Enhances the strength of cured adhesives;
*Prevent sedimentation or sagging, improve dispersion performance;
*Viscosity is less affected by heat or high temperature.
Applications
Organic Silicone Adhesives
As reinforcing filler, fumed silica has excellent reinforcing properties and it’s used to improve the mechanical properties of silicone sealant, and can improve its rheological properties.
Epoxy Adhesive
Fumed silica is a very efficient rheology control agent with functions of sag-resistance, mechanical property adjustment, and keeping viscosity stability during storage. When added in appropriate amounts, epoxy adhesives can exhibit excellent rheological properties.
MS/SMP/SPU Adhesives
The polar groups have affinity for the silyl hydroxyl groups on the surface of fumed silica, and the fumed silica gathers around the polar groups in large quantities, and produces synergistic effects and bridging effects with hydroxyl or amino compounds to promote thickening and thixotropic effects.
Acrylic adhesives
After the shear force is removed, the fumed silica network and hydrogen bond reorganization are restored, preventing the precipitation of adhesives and sealants during storage and sag during curing.
Solvent or liquid Adhesives
Fumed silica has large specific surface area, strong adsorption performance and easy suspension. It can absorb a large number of water molecules in water and swell into extremely fine particles to form a stable suspension. It is an ideal anti-settling agent.
Hot-melt Adhesive (HMA)/ Hot Glue
Under the action of electrostatic repulsion and steric repulsion, the primary particles of fumed silica or smaller agglomerates shield the van der Waals attraction, so that the particles no longer aggregate and maintain higher stability.
※For more product specifications, sample-test or quotation, send email to hifull@hifull.com or contact: +86 18571019514
