New Easy-to-Disperse (E2D) AEROSIL® fumed silica grades

Blog Archive | 2 minutes  | Author: Danielle Williams , MChem.

AEROSIL® fumed silica has long been used as a rheology modifier in coatings, adhesives and sealants as it imparts thixotropic properties at low additions therefore improving stability, anti-settling and anti-sagging, in addition to providing mechanical reinforcement.  Despite its benefits, fumed silica is a very low-density powder and can be difficult to wet out, especially surface-treated hydrophobic grades, and requires energy-intensive mixing to ensure a proper dispersion is achieved. 

Thanks to a new innovative production process, Evonik has developed four easy-to-disperse (E2D) silica grades - AEROSIL® E 805, AEROSIL® E 812, AEROSIL®  E 972 and AEROSIL® E 9200 - which offer the same outstanding performance as their "R" counterparts without the need for high shear mixing (Figure 1).

 

Fig1_new easy to disperse (E2D) fumed silica grades from Evonik

Figure 1. Evonik has developed four new silica grades - AEROSIL® E 805, AEROSIL® E 812, AEROSIL®  E 972 and AEROSIL® E 9200 - which can be incorporated without grinding or milling.

 

AEROSIL® E easy-to-disperse (E2D) silicas can simplify complex production processes

Successful use of AEROSIL® silica in coatings formulations requires the use of high shear mixing in order to achieve a homogenous dispersion. Typically paint manufacturers first employ a pre-dispersion step using a dissolver to wet out and loosely break up the agglomerates, followed by an intensive bead milling stage to fully disperse the particles. With the new AEROSIL® E2D grades, it is possible to eliminate the grinding step and incorporate fumed silica using lower shear mixers (Figure 2) therefore saving both production time and cost. 

With the new E2D grades, manufacturers can:

  • reduce energy consumption
  • reduce manpower required
  • reduce machine cleaning and maintenance
  • increase efficiency and sustainability

 

Fig2 incorporation of AEROSIL fumed silica into coatings

Figure 2. The new easy-to-disperse AEROSIL® grades can be incorporated via low shear dispersion thereby eliminating the time-consuming and energy-intensive milling/grinding stage.

 

Grindometer values (by TIDAS) for dissolver incorporated hydrophobic AEROSIL® grades and their E2D versions are shown in Figures 3 and 4.  In all instances the grind is significantly better with the new "E" grades and due to the ease of incorporation, it is also now possible to adjust rheology by post-adding E2D grades.

Fig3 grindometer of AEROSIL R 805 and R812 versus the new easy-to-disperse grades

Figure 3. Grindometer of AEROSIL® R 805 and AEROSIL® R 812 versus their new easy-to-disperse equivalents.  Both silicas were incorporated using a dissolver and a significantly better dispersion is achieved with the new "E" grades.

Fig4 grindometer of AEROSIL R 972 and R 9200 versus the new easy-to-disperse grades

Figure 4. Grindometer of AEROSIL® R 972 and AEROSIL® R 9200 versus their new easy-to-disperse equivalents.  Both silicas were incorporated using a dissolver and a significantly better dispersion is achieved with the new "E" grades.

 

Drop-in replacements for existing hydrophobic AEROSIL® grades

The new easy-to-disperse grades are chemically identical to their corresponding AEROSIL® R grades so can be used as a 1:1 replacement in existing formulations without compromising on performance. At the same addition levels, E2D grades provide the same viscosity profile, gloss and haze as the R grades even when incorporated under low shear. AEROSIL® E 805, AEROSIL® E 812, AEROSIL®  E 972 are therefore well suited to rheology control in both waterborne and solventborne formulations and find use in Automotive, Marine and Protective, and General Industrial coatings (Table 1).  AEROSIL® E 9200 is based on the structure modified AEROSIL® R 9200 and provides limited rheological effect; instead it is used at higher addition levels (ca. 5 wt%) for enhanced scratch and abrasion resistance.

 

Fig5 table of properties of AEROSIL E2D grades

Table 1. Benefits and recommended applications of the new AEROSIL® E range.  These products can be used as 1:1 replacements for their regular "R" counterparts without compromising on peformance.

 

Summary

Evonik's innovative AEROSIL® easy-to-disperse silicas can be used as 1:1 replacements for formulations containing AEROSIL® R 805, AEROSIL® R 812, AEROSIL® R 972 and AEROSIL® R 9200.  These new silicas eliminate the need for intensive grinding during manufacturing and can be incorporated using only a dissolver therefore reducing both production time and cost.  

For further information and samples, contact your LI account manager or call us on +44 (0)1827 314151.

Author: Danielle Williams , MChem.

Danielle studied chemistry at the University of York, where she earnt her MChem with a focus on Green Chemistry.  As a senior member of the sales team, she is an expert in the field of Coatings and Inks.