NYACOL Transparent High Refractive Index Sols

Transparent high refractive index materials are of interest as a coating additive for reducing reflection loss in a number of technologically important applications such as coatings for TFT/LCD displays, lens coating and LED lighting. NYACOL offers five material types which are relatively high in refractive index and the particle size is small enough that the dispersion is optically transparent.

The NYACOL materials are hydrous sols, meaning the metal oxide particles contain water of hydration as well as the counter-ion for each material type. The implication of this is that the solid phase is not fully condensed into the corresponding oxide, and the density is lower and the solid phase refractive index is also lower than theoretical. The lower density is advantageous to reduce the weight required to achieve a given volume loading of the metal oxide, counterbalanced by a lower contribution to increased refractive index.

We developed an arbitrary method for estimating the refractive index and density of the solid phase of our sols.  This data is presented below.

Grade/Products Oxide Sol Wt.% Oxide Solid Phase RI Solid Phase Density Carrier Typical Sol NTU as Supplied
SN15 SNO2 15 1.8 4.25 water 22
JL627S Sb2O5 28 1.70 3.09 water 145
Zr10/15 ZrO2 15 1.86 4.01 water 25
TiSol A TiO2 20 2.07 3.22 water 500
Ceria acetate CeO2 20 2.02 5.09 water 213

In formulating the high RI coating, the user will need these parameters to determine the amount of our sol to use to meet a given RI target. The choice of oxide will depend on the chemistry of the coating and the coupling agent options available. We recommend formulating the coating using the volume fractions of the coating components which requires knowledge of the resin density and RI, as well as the solid phase density and RI for the NYACOL sol. Please contact NYACOL to discuss your requirements.

For low refractive index particles, we offer amorphous silica as our lowest refractive index material presently. The amorphous silica has outstanding transparency with a refractive index of the particle of 1.45 and a particle density of 2.2 g/ml.

For more specific information, please refer to the Products pages to download a data sheet.