Thermal HRI coating reaches RI > 1.8 and 8H pencil hardness on specialty glass
A specialty glass manufacturer
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01
The challenge
The glass manufacturer needed a high refractive index coating on display glass (0.7 mm) that could achieve RI 1.85 with maximum hardness. Existing HRI coatings from other suppliers could not reach 8H pencil hardness at these RI levels, and lower cure temperatures were desired to reduce energy costs.
02
Our approach
Kriya developed three thermal-curable HRI formulation variants (V1, V2, V3), testing cure temperatures from 130°C to 200°C. Formulation optimisation focused on reducing haze through organic compound reduction (V2, V3) while maintaining RI and hardness targets. Low-outgassing variants were developed in response to customer requirements.
03
The outcome
V1 achieved RI 1.85 and 8H pencil hardness across all cure temperatures (130–200°C). V2 delivered the lowest haze: 0.49% at 200°C cure. All variants achieved 100% adhesion (ASTM D3359). Higher cure temperatures reduced haze significantly, with the majority of improvement occurring at 160°C.
Why Kriya
Kriya’s sol-gel chemistry uniquely enables 8H pencil hardness at RI 1.85 via thermal cure alone, with tuneable cure temperatures and low-outgassing options that competitors cannot match.
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