In the field of optical films and functional coatings, achieving a low refractive index without sacrificing transparency remains a technical challenge. Conventional solid nanoparticles often increase scattering or require complex synthesis routes. N-1160-70 offers a different approach: a nanoscale, hollow-structured silica dispersion designed specifically for low-refractive-index coatings, antireflective layers, and UV-curable optical films.
What Is N-1160-70?
N-1160-70 is an aqueous or solvent-based dispersion of hollow silica nanoparticles. Unlike traditional solid silica particles, the hollow interior reduces the effective refractive index of the material while maintaining the intrinsic physical, optical, and chemical properties of silica.
The "70" in the product designation typically refers to the solid content or a specific grade parameter. The key feature is the hollow internal cavity, which traps air (refractive index ≈ 1.0) inside each nanoparticle. This structure directly lowers the overall refractive index of the dry coating, making N-1160-70 suitable for applications where index matching or antireflection is required.
Technical Properties and Advantages
Low Refractive Index
The hollow morphology gives N-1160-70 a refractive index significantly lower than that of solid silica (n ≈ 1.46). Depending on the hollow-to-solid ratio and formulation, the effective refractive index can range from approximately 1.20 to 1.30. This is close to the theoretical optimum for single-layer antireflective coatings on glass or polymer substrates (n ≈ 1.22–1.25).
High Optical Transparency (>95% Transmittance)
The nanoparticles are dispersed to a primary particle size in the nanometer range-typically below 50–70 nm. This size is well under the wavelength of visible light (380–780 nm), which minimizes Rayleigh scattering. As a result, coatings containing N-1160-70 maintain excellent clarity with total transmittance exceeding 95% and negligible haze. This transparency is essential for displays, optical lenses, and high-end film applications.
Compatibility with UV-Curable Resins
N-1160-70 is designed for use with low-refractive-index binder resins, particularly in UV-curable systems. The dispersion can be directly incorporated into acrylate-based or other photopolymerizable formulations without causing excessive viscosity increase or phase separation. After UV curing, the hollow nanoparticles remain embedded in the matrix, preserving their low-index contribution and improving mechanical durability.
Silica Surface Chemistry
Because the particles are made of silica, they offer good hardness, chemical resistance, thermal stability, and weatherability. The surface can be modified or functionalized to improve compatibility with organic resins, but even in its standard form, N-1160-70 provides the robustness expected from silica-based nanomaterials.
Applications of N-1160-70
Antireflective (AR) Coatings
The most common application is in antireflective coatings for displays, touch panels, cover glasses, and solar cells. When a low-index layer containing N-1160-70 is combined with a high-index layer (e.g., TiO₂ or Nb₂O₅ nanoparticles), a multilayer interference stack reduces surface reflection to below 0.5–1.0%. This improves contrast, brightness, and energy transmission.
Optical Enhancement Films (Display Films)
In the display industry, optical films such as anti-glare, anti-reflection, and brightness enhancement films benefit from low-index layers. N-1160-70 enables coating formulations that are both highly transparent and index-tuned. It can be used as a nano-coating additive in roll-to-roll processes for PET, TAC, or PC films.
Fiber Optic Coatings and Coupling Adhesives
Optical fibers require cladding materials with precisely controlled refractive indices to confine light within the core. N-1160-70 can be incorporated into UV-curable fiber coatings or coupling adhesives to lower the refractive index while maintaining adhesion and flexibility. It is also useful in index-matching adhesives between optical components, where reducing Fresnel reflection losses is critical.
UV-Curable Optical Coatings
For UV coatings used in consumer electronics, automotive displays, or medical optics, N-1160-70 serves as a functional additive that lowers the refractive index without blocking UV curing or yellowing. It is compatible with common photoinitiators and monomers, allowing formulators to create clear, low-index topcoats or intermediate layers.
Nanocoating Additive for Antifingerprint or Antisoiling Layers
Although not primarily a hydrophobic agent, the porous or hollow nature of the silica particles can be combined with fluorinated compounds to produce low-index, low-friction surfaces. In some advanced coatings, N-1160-70 is part of a hybrid system that balances antireflection and easy-clean properties.
Formulation Considerations
When using N-1160-70, a few practical points are worth noting:
Resin Selection: The best results are obtained with low-refractive-index binders (n ≈ 1.45–1.50), such as fluorinated acrylates or certain polyurethanes. Matching the binder index to the hollow silica index minimizes scattering.
Particle Loading: Higher loading of N-1160-70 lowers the overall refractive index but may affect mechanical strength and adhesion. Typical loadings range from 10–50 wt% on a solids basis.
Dispersion Stability: The product is supplied as a stable dispersion. However, shear rates, pH, and co-solvents should be controlled to prevent agglomeration.
Curing Conditions: UV energy and photoinitiator type should be optimized because hollow nanoparticles can slightly scatter or absorb UV light if poorly dispersed.
Conclusion
N-1160-70 is a practical solution for creating low-refractive-index layers in optical coatings, UV-curable films, and fiber optic adhesives. Its hollow silica structure delivers a refractive index as low as 1.20–1.30, combined with >95% transparency and good compatibility with UV resins. By integrating N-1160-70 into antireflective stacks or index-matching layers, formulators can reduce reflection losses, improve display contrast, and enhance light transmission without compromising mechanical or chemical stability.
For coating engineers seeking a reliable, non-exaggerated nanomaterial for index control, N-1160-70 provides a proven path from lab testing to production-scale optical films.