Product Overview
N-1160-70 is a nano-scale hollow silica nanoparticle dispersion formulated in propylene glycol monomethyl ether (PGME). The unique hollow internal cavity structure significantly reduces the effective refractive index of the material compared to conventional solid silica particles, while maintaining the intrinsic physical, optical, and chemical properties of silica.
The nanoparticles are dispersed to a primary particle size of 60–70 nm, ensuring excellent optical clarity with minimal light scattering. With a refractive index as low as 1.16, N-1160-70 is specifically designed for low-refractive-index coatings, UV-curable optical films, and antireflective applications. It can be combined with low-refractive-index base resins for use in antireflective coatings, anti-glare films, fiber optic coatings, adhesive coupling layers, optical display films, and as a functional nano-coating additive.
Key Features & Benefits
| Feature | Benefit |
|---|---|
| Hollow nanoparticle structure | Ultra-low refractive index (1.16) - significantly lower than solid silica (≈1.46) |
| Nano-scale particle size (60–70 nm) | High transparency (>95% transmittance) with negligible light scattering |
| PGME solvent system | Excellent compatibility with UV-curable resins and common coating formulations |
| Silica shell composition | Good hardness, chemical resistance, thermal stability, and weatherability |
| Low viscosity (15–25 mPa·s) | Easy handling and direct incorporation into coating formulations |
| Low relative density (0.85–0.95) | Lightweight dispersion reduces overall coating weight |
Technical Specifications
| Parameter | Value |
|---|---|
| Appearance | Semi-transparent liquid |
| Nanosilica content (wt%) | 20 |
| Viscosity at 25°C (mPa·s) | 15–25 |
| Solvent: PGME (wt%) | 75–80 |
| Refractive index (nD²⁵) | 1.16 |
| Relative density | 0.85–0.95 |
| Nanoparticle size | 60–70 nm |
Note: PGME (Propylene Glycol Monomethyl Ether, also known as 1-methoxy-2-propanol) is a common solvent in UV-curable and optical coating formulations, offering good solubility for acrylates and other resins.
Optical Performance
The refractive index of 1.16 is among the lowest achievable with silica-based nanoparticles. This value is close to the theoretical optimum for single-layer antireflective coatings on glass or polymer substrates (approximately 1.22–1.25). The hollow interior (air-filled, n≈1.0) combined with the thin silica shell enables this exceptionally low index.
Coatings formulated with N-1160-70 can achieve total transmittance exceeding 95% in the visible range, with minimal haze due to the nanoparticle size being well under the wavelength of visible light (380–780 nm).
Applications
Antireflective (AR) Coatings
When used as a low-index layer in multilayer interference stacks (paired with high-index materials such as TiO₂ or Nb₂O₅ nanoparticles), N-1160-70 helps reduce surface reflection from 4–5% to below 0.5–1.0%. Typical applications include:
Display panels and touch screens
Cover glasses for consumer electronics
Solar cell cover glass
Optical lenses and camera modules
Optical Enhancement Films
For display films used in smartphones, tablets, laptops, and automotive displays, N-1160-70 serves as a nano-coating additive that provides low refractive index without sacrificing transparency. It is compatible with roll-to-roll coating processes on PET, TAC, or PC substrates.
Fiber Optic Coatings
Optical fiber cladding requires precise refractive index control to confine light within the core. N-1160-70 can be incorporated into UV-curable fiber coatings or used in index-matching adhesives for optical coupling, reducing Fresnel reflection losses at connection points.
UV-Curable Optical Coatings
For UV-cured systems in consumer electronics, medical optics, or automotive displays, N-1160-70 lowers the refractive index without interfering with UV curing or causing yellowing. The PGME solvent is compatible with common photoinitiators and monomers.
Formulation Guidelines
Resin Selection: For best results, use low-refractive-index base resins (n≈1.45–1.50) such as fluorinated acrylates or certain polyurethanes.
Loading Range: Typical solid loading of N-1160-70 in final formulation is 10–50 wt% (based on nanosilica content). Higher loading further reduces refractive index but may affect mechanical properties.
Mixing: Gentle agitation is recommended. Avoid prolonged high-shear mixing which could potentially damage the hollow particle structure.
Solvent Compatibility: PGME is miscible with many common solvents (e.g., PGMEA, ethanol, acetone). Test compatibility with your resin system before scale-up.
Curing: Hollow nanoparticles may slightly scatter UV light; adjust UV intensity or exposure time as needed to ensure complete curing.
Handling & Storage
Storage: Keep container tightly closed in a cool, dry, well-ventilated area away from direct sunlight and heat sources.
Temperature: Avoid freezing and excessive temperatures above 40°C.
Shelf Life: Typically 12 months from date of manufacture under recommended storage conditions.
Safety: PGME is flammable. Use appropriate personal protective equipment and ensure adequate ventilation. Refer to Safety Data Sheet (SDS) before use.
Packaging
Available in various packaging configurations. Please contact us for specific packaging options and volume pricing.
Frequently Asked Questions (FAQ)
Q: Why is the refractive index as low as 1.16?
A: The hollow internal cavity of each nanoparticle traps air (refractive index ≈1.0). The combination of a thin silica shell and an air core effectively reduces the overall refractive index of the dried coating to 1.16.
Q: What is PGME and why is it used?
A: PGME (Propylene Glycol Monomethyl Ether) is a common industrial solvent with good solvency for UV resins and acrylates. It provides a stable dispersion medium for hollow silica nanoparticles and evaporates during coating and curing processes.
Q: How does the particle size (60–70 nm) affect transparency?
A: Particles smaller than approximately 1/10th of the visible light wavelength (380–780 nm) cause very low light scattering. At 60–70 nm, N-1160-70 produces coatings with >95% transmittance and minimal haze.
Q: Can N-1160-70 be used in water-based systems?
A: This specific grade is formulated in PGME, a solvent-based system. For water-based applications, please contact us for alternative grades.
Q: What is the recommended loading for antireflective coatings?
A: Typical loading ranges from 20–40 wt% (solids basis) depending on the desired refractive index and layer thickness. We recommend conducting a design of experiments (DOE) for your specific resin system.
Q: Is the product stable during long-term storage?
A: When stored as recommended, N-1160-70 remains stable for 12 months. Periodic mixing before use is recommended to ensure uniform dispersion.
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