Nanopaste Dispersion Technology
A common challenge in the application of nanomaterials is that nanoparticles, due to their high surface energy, tend to agglomerate in the system, leading to increased particle size, reduced transparency, or even sedimentation and phase separation. Our dispersion technology, through surface modification of particles and matching dispersants, keeps the nanoparticles in a monodisperse state within the carrier. With particle size controlled to approximately 20 nm – well below the visible light wavelength (380–780 nm) – the nanoparticles themselves do not cause light scattering, and the cured coating maintains high transparency.
From a product-form perspective, we offer two carrier systems: acrylate monomer carriers and organic solvent carriers. The monomer carrier can be used directly as a UV-curable formulation without the need for additional solvents, making it suitable for thicker coatings or applications with VOC constraints. The solvent carrier, with lower solid content, is suited for precision coating processes requiring extremely thin coatings (nanoscale film thickness), where the solvent evaporates to form a uniform accumulation layer of nanoparticles.
I. High-Refractive-Index Nano-Zirconia Sol
Zirconia (ZrO₂) has a high bulk refractive index (approximately 2.1–2.2). Dispersing it as nanoparticles into UV resins effectively raises the overall refractive index of the composite. Our zirconia sol is supplied in an acrylate monomer carrier, with high solid content and low viscosity, offering good compatibility in formulations.
Key technical specifications:
Particle size: nanoscale, controlled to approximately 20 nm, ensuring good coating transparency
Refractive index contribution: can raise the coating's refractive index to 1.715 (D-line, λ = 589.3 nm)
Carrier: acrylate monomer, which participates in UV crosslinking
Dispersion stability: optimised treatment provides long-term storage stability without sedimentation
In addition to the conventional monomer-carrier grade, we also offer a solution-type product, N-1030S. This grade uses organic solvents to reduce solid content and is specifically designed for nanoscale film-thickness coating applications. In scenarios requiring ultra-thin coatings (e.g., below 100 nm), conventional high-solid-content sols are difficult to apply uniformly. N-1030S, by lowering solid content and adjusting the solvent system, enables the coating fluid to form a continuous, uniform film even at low coating weights.
Zirconia sol is primarily used in optical coating formulations requiring high refractive indices, such as high-refractive-index brightness enhancement films, optical compensation films, and high-refractive-index encapsulation for Micro‑LED colour conversion layers. Additionally, high-refractive-index nano-zirconia can be used to enhance UV resin formulations – i.e., adding zirconia sol to the resin to further increase the composite system's refractive index to meet more demanding design specifications. It can also be combined with low-refractive-index materials for refractive-index gradient design to achieve specific optical functions.
II. Low-Refractive-Index Hollow Silica Sol
Unlike solid nanoparticles, hollow silica (SiO₂) nanoparticles contain an internal air cavity. Since the refractive index of air is approximately 1.0, the hollow structure gives the particles an effective refractive index significantly lower than that of solid silica (bulk refractive index ~1.46). By adjusting the ratio of shell thickness to cavity diameter, the effective refractive index can be tuned over a broad range, with a minimum achievable value of approximately 1.15.
Key technical features:
Effective refractive index: as low as 1.15 (adjustable via shell‑to‑cavity ratio)
Transmittance: maintains >95% transmittance
Particle size: nanoscale, does not affect visible-light transmission
Dispersion system: supplied in acrylate monomer or organic solvent carriers, with good dispersion stability
The anti‑reflection mechanism of hollow silica differs from that of fluorine-modified low-refractive-index resins. Fluorine-modified resins achieve low refractive index through their intrinsic molecular structure, whereas hollow silica achieves it through the particle's hollow structure; the two can be used in combination. Adding hollow silica sol to anti‑reflection coating formulations reduces the coating's refractive index while maintaining good mechanical strength, compensating for the hardness limitations of pure resin coatings.
This material is suitable for high-performance anti‑reflection films, optical fibre coatings, refractive-index matching layers for optical devices, and anti‑reflective coatings for photovoltaic glass.
III. Solid Nano-Silica Sol (N-1466)
Solid nano‑silica sol N‑1466 features an organic–inorganic hybrid spherical structure, combining inorganic SiO₂ with organic components at the nanoscale. Because nano‑silica particles have high hardness, incorporating them into UV‑curable systems significantly improves the coating's surface hardness and abrasion resistance, while maintaining high transparency.
Key technical specifications:
Particle size: approximately 10 nm, well below the visible-light wavelength
Particle structure: spherical organic–inorganic hybrid structure
Transparency: nanoscale particle size imparts excellent transparency to the system
Wear resistance: the spherical structure provides a low coefficient of friction and high hardness
Another notable feature of this product is its ability to significantly reduce UV‑curing volumetric shrinkage. UV‑curable resins typically undergo some degree of volumetric shrinkage during polymerisation (about 5–10%), which can be detrimental in applications requiring precise dimensional control, such as microelectronic bonding and 3D printing. The high loading of nano‑silica filler acts as a skeletal support within the system, effectively reducing the curing shrinkage.
Primary application areas include:
Hard coatings for optical films: as a protective hard coat on high‑transparency substrates such as PMMA or PC, improving abrasion and scratch resistance
High‑precision 3D printing: controlling volumetric shrinkage of printed parts to enhance dimensional accuracy
Microelectronic bonding: used as a filler in adhesive applications requiring low shrinkage