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 is restored, viscosity from increasing, this prevents adhesives and sealants from sagging during the curing process.
What functions fumed silica brings to Adhesives & Sealants?
HIFULL® Fumed Silica Product Has Below Excellent Properties
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.
Application In Adhesives(HIFULL® Product Advisor)
| System | Function | Recommend Dosage | Hydrophobic Fumed Silica Suggest | Hydrophilic Fumed Silica Suggest |
|---|---|---|---|---|
| Epoxy Adhesive | sag-resistance, settling-resistance | 1.5%-3.0%0.25%-2.0% | HB-139 HB-151 | HL-200 HL-300 |
| Polyurethane Adhesive | sag-resistance, rheology control, thixotropic, viscosity increase | 1%-5% | HB-139 HB-151 | HL-200 HL-300 |
| Acrylic, cyan acrylic, Anaerobic acrylic, UV-cured acrylic adhesives | settling-resistance, rheology control, thixotropic | 1%-5% | HB-139 HB-151 | HL-200 HL-300 |
| Organic silicone adhesives | reinforce, rheology control | 5%-15% | HB-132 HB-630 HB-620 HB-612 HB-615 | HL-150 HL-200 |
| MS/SMP/SPU adhesives | sag-resistance, rheology control, thixotropic, viscidity increase | 1%-5% | HB-151 HB-139 | HL-200 |
| Rubber-based adhesives (BR /CR /NR) | rheology control, thixotropic, reinforce | 1%-5%4%-8% | HB-151 | HL-200 |
| Pressure sensitive adhesives | viscidity increaserheology control, thixotropic | 1%-5%4%-8% | / | HL-200 |
Application In Sealants(HIFULL® Product Advisor)
| System | Function | Recommend Dosage | Hydrophobic Fumed Silica Suggest | Hydrophilic Fumed Silica Suggest |
|---|---|---|---|---|
| Polyurethane Sealants | sag-resistance, thixotropic, extrusion efficiency, stability( moisture control) | 3%-7% | HB-139 HB-151 | HL-200 |
| Acrylic Sealants | sag-resistance, settling-resistance, rheology control, thixotropic, extrusion efficiency | 3%-7% | HB-151 | HL-200 |
| Organic silicone | sag-resistance, reinforcement, rheology control, thixotropic, extrusion efficiency, stability( moisture control) | 5%-15% | HB-132 HB-630 HB-620 HB-612 HB-615 | HL-150 HL-200 |
| MS/SMP/SPU sealants | reinforce,extrusion efficiency,stability( moisture control) | 5%-10% | HB-139 HB-151 | / |
| butyl rubber-based sealants | sag-resistance, reinforce | 3%-7% | HB-151 | HL-200 |
| Polysulfide sealant | Reinforce, rheology control, thixotropic, | 3%-7% | HB-151 HB-139 | HL-200 |
ABOUT HIFULL
Our main products are fumed silica SiO2, fumed titanium dioxide TiO2, and fumed alumina Al2O3. We get 20+ years of expertise and 20,000 tons of annual capacity. We supply total of 23 grades of hydrophilic & hydrophobic fumed silica. We get registration of REACH and pre-registration of K-REACH & KKDIK. We are the leading setting body of ISO18473-1:2015, ISO18473-3:2018, and ISO 23157:2021. Learn More About Hifull
