1. Introduction

High transparency nano colorants are pigment pastes with particle sizes controlled at the nanoscale (typically D90 ≤ 100 nm), delivering exceptional light transmission and color performance in transparent resin systems. As industries such as high-end wood coatings, plastic coatings, optical films, and electronic displays increasingly demand transparent coloring solutions, high transparency nano colorants have become critical raw materials. Dongguan DENSON Functional Materials Co., Ltd. has developed a series of high transparency nano colorant products using advanced nanodispersion technology and hyperdispersant systems, achieving nanoscale control of pigment particle size while maintaining high tinting strength and weather resistance. This article provides an in-depth analysis of the dispersion mechanism and optical performance of DENSON high transparency nano colorants, supported by three application case studies.

2. Technical Features and Mechanism

The core technology of high transparency nano colorants lies in the nanoscale dispersion and stabilization of pigment particles. Nanoscale pigment particles (<100 nm) significantly reduce scattering of visible light (wavelength 400-700 nm), thereby achieving high transparency. DENSON high transparency nano colorants employ the following key technologies:

(1) Nanoscale milling technology: Using horizontal bead mills with 0.3-0.5 mm zirconium oxide beads, pigment particles are milled to D90 ≤ 80 nm, with specific surface area increased to 50-80 m²/g, significantly enhancing tinting strength.

(2) Hyperdispersant anchoring mechanism: Polymeric hyperdispersants containing multiple anchoring groups (carboxyl, amino, phosphate ester groups) bind firmly to pigment surfaces through multi-point adsorption. Solvated chain segments form steric hindrance in the resin medium, preventing nanoparticle agglomeration.

(3) Refractive index matching design: The carrier resin refractive index (1.48-1.52) is closely matched to the application system resin, reducing interfacial reflection and further enhancing transparency.

(4) Optical performance metrics: Visible light transmittance ≥ 85% (550 nm, 20 μm film thickness), haze ≤ 3%, color difference ΔE ≤ 0.8 (same batch).

3. Application Case Study 1: High-end Wood Furniture Transparent Coloring

A premium furniture manufacturer required transparent mahogany coloring in a nitrocellulose (NC) clear coat system, demanding visible wood grain, uniform color, and yellowing resistance. Using DENSON high transparency nano colorants (iron oxide red + transparent yellow) at 3.5% loading, excellent transparent coloring was achieved in NC wood varnish.

Key performance: Visible light transmittance 88% (550 nm), wood grain clarity retention ≥ 95%, tinting strength 40% higher than conventional colorants, QUV 500h yellowing ΔE ≤ 1.5 (GB/T 1865-2009), adhesion grade 1 (GB/T 9286-1998).

4. Application Case Study 2: PET Plastic Film Transparent Coloring

An optical film manufacturer required a transparent blue coating on PET substrate for architectural heat-insulation films, demanding high visible light transmittance and near-infrared blocking. Using DENSON high transparency nano blue colorant at 2.8% loading in an acrylic polyurethane coating system applied to PET film.

Key performance: Visible light transmittance 82% (550 nm), near-infrared blocking ≥ 65% (900-2500 nm), haze 2.1%, boiling water resistance 100°C/30min no delamination, adhesion grade 0 (GB/T 9286-1998 cross-cut method), weather resistance QUV 1000h ΔE ≤ 2.0.

5. Application Case Study 3: Electronic Display Panel Edge Coloring

A display panel manufacturer required a transparent black light-shielding layer on glass substrate edges, demanding high opacity with sharp edge definition. Using DENSON high transparency nano black colorant (nanoscale carbon black) at 6% loading in an epoxy acrylate UV-curable system.

Key performance: Optical density (OD) ≥ 4.0 (10 μm film), edge resolution ≤ 20 μm, curing energy 500 mJ/cm², adhesion 5B (ASTM D3359), thermal cycling -40°C to 85°C / 100 cycles no cracking.

6. Key Selection Parameters and Usage Recommendations

| Parameter | Wood Coatings | Plastic Films | Electronic Displays |

| Recommended particle size | D90 ≤ 80nm | D90 ≤ 60nm | D90 ≤ 50nm |

| Loading level | 2-5% | 1.5-3% | 4-8% |

| Visible light transmittance | ≥ 85% | ≥ 80% | ≥ 75% |

| Key standard | GB/T 1865 | GB/T 9286 | ASTM D3359 |

Usage recommendations:

(1) High transparency nano colorants are shear-sensitive; add under low-speed agitation to avoid dispersant desorption from high shear.

(2) Evaluate compatibility with the application system before use; perform a rub-up test to assess flooding/floating tendency.

(3) Recommended storage temperature 5-35°C; avoid freezing which causes particle agglomeration.

(4) For more product information, refer to DENSON high transparency nano colorant product pages.

7. Conclusion

High transparency nano colorants achieve the union of high transparency and high tinting strength through nanoscale pigment dispersion, hyperdispersant stabilization, and refractive index matching technology. DENSON high transparency nano colorants demonstrate excellent optical performance and application stability in wood coatings, plastic films, and electronic displays, making them ideal for high-end transparent coloring applications. Selection should be based on the application system's refractive index, curing method, and performance requirements, choosing appropriate particle size and loading levels.

8. FAQ

Q1: What is the essential difference between high transparency nano colorants and conventional colorants?

A: The essential difference lies in pigment particle size. High transparency nano colorants have pigment particle size D90 ≤ 100 nm, which scatters visible light minimally, resulting in high transparency; conventional colorants typically have pigment particle sizes of 1-5 μm, which scatter visible light and reduce transparency. Nano colorants have larger specific surface area, with tinting strength typically 30-50% higher than conventional colorants, but require more advanced dispersion technology.

Q2: Why do nano colorants tend to re-agglomerate (re-thicken), and how can this be resolved?

A: Nanoparticles have large specific surface area and high surface energy, making them thermodynamically prone to agglomeration. If dispersant adsorption is insufficient or storage conditions are improper (high temperature, freezing), particles will re-aggregate causing re-thickening. Solutions: Select colorants with anchoring-group-rich hyperdispersants, control storage temperature at 5-35°C, filter through 800-mesh screen before use, and avoid direct mixing with strong polar solvents.

Q3: How is the transparency of high transparency nano colorants evaluated?

A: Standard evaluation method: Add colorant at specified loading to a clear varnish, prepare a 20 μm wet film, cure, and measure visible light transmittance at 550 nm using a spectrophotometer (GB/T 1729-1979), while measuring haze with a hazemeter (GB/T 2410-2008). Quality nano colorants should achieve transmittance ≥ 85% and haze ≤ 3%.

Q4: What resin systems are high transparency nano colorants compatible with?

A: DENSON high transparency nano colorants are compatible with nitrocellulose (NC), acrylic, polyurethane (PU), epoxy, UV-curable, and other resin systems. However, colorants with different carriers have varying compatibility with specific resins; compatibility testing should be performed before use. Generally, ester/alcohol ether carrier colorants offer good universality, while water-based colorants are suitable for aqueous systems.

Q5: Is the weather resistance of nano colorants superior to conventional colorants?

A: The weather resistance of nano colorants primarily depends on the pigment's own weather resistance grade, not particle size. However, nanoscale dispersion results in more uniform pigment distribution, reducing stress concentration caused by local pigment agglomeration, so at the same pigment grade, nano colorants generally demonstrate more stable weather resistance performance. For outdoor applications, pigments with weather resistance grade ≥ 7-8 (GB/T 250-2008) are recommended.