1. Introduction

High transparency nano colorants have emerged as essential coloring materials for applications requiring both vivid color and optical clarity. Unlike conventional pigment pastes that produce opaque or hazy coatings, nano colorants with particle sizes below 100 nm enable transparent coloring that preserves substrate visibility and light transmission. Dongguan DENSON Functional Materials Co., Ltd. offers a comprehensive range of high transparency nano colorant products tailored for diverse industries. This article presents three detailed application case studies demonstrating the practical performance and benefits of DENSON high transparency nano colorants in cosmetics packaging, architectural glass coatings, and LED lighting applications, providing technical reference for engineers and product developers.

2. Technical Features and Mechanism

High transparency nano colorants are pigment dispersions where the pigment primary particle size is controlled at the nanoscale (D90 ≤ 80 nm) through advanced wet milling and hyperdispersant stabilization. The key technical features include:

(1) Nanoscale particle size control: Pigment particles are milled to D90 ≤ 80 nm using 0.3 mm zirconium oxide beads in horizontal bead mills, minimizing Rayleigh scattering of visible light (scattering intensity ∝ 1/λ⁴ for particles << λ).

(2) Hyperdispersant stabilization: Polymeric dispersants with molecular weights of 5,000-20,000 g/mol provide multi-point anchoring on pigment surfaces and steric stabilization in resin media, preventing nanoparticle re-agglomeration.

(3) High color strength: Specific surface area of 50-80 m²/g results in 30-50% higher tinting strength compared to conventional colorants, reducing required loading levels.

(4) Broad compatibility: Available in solvent-based (ester/alcohol ether carriers), water-based, and UV-curable carrier systems to match diverse application requirements.

3. Application Case Study 1: High-end Cosmetics Packaging Transparent Coloring

A luxury cosmetics brand required transparent emerald green coloring on glass perfume bottle caps using a UV-curable acrylic coating, demanding high gloss, chemical resistance, and batch-to-batch color consistency. DENSON high transparency nano phthalocyanine green colorant was selected at 2.5% loading in a UV-curable urethane acrylate system.

Key performance: Visible light transmittance 84% (550 nm, 15 μm film), gloss 60° ≥ 95 GU (GB/T 9754-2007), alcohol resistance (ethanol 500 g load / 100 cycles) no color loss, adhesion 5B (ASTM D3359), curing energy 800 mJ/cm², batch color difference ΔE ≤ 0.5. The nano colorant's high tinting strength reduced pigment loading by 40% compared to conventional alternatives, improving coating clarity and reducing cost.

4. Application Case Study 2: Architectural Glass Heat-insulating Transparent Coating

An architectural coating manufacturer developed a transparent heat-insulating coating for building glass, requiring high visible light transmittance combined with near-infrared (NIR) blocking to reduce air conditioning energy consumption. DENSON high transparency nano blue colorant (nanoscale cobalt aluminate) at 3.0% loading was combined with nano cesium tungsten bronze (Cs₀.₃₃WO₃) NIR absorber in a silicone-acrylic resin system applied to 6 mm float glass.

Key performance: Visible light transmittance 70% (550 nm), NIR blocking ≥ 75% (900-2500 nm), solar heat gain coefficient (SHGC) 0.45 (GB/T 2680-2021), haze ≤ 2.5%, pencil hardness 3H (GB/T 6739-2006), outdoor exposure 1000h ΔE ≤ 1.8, adhesion grade 1 (GB/T 9286-1998). The coating reduced indoor temperature by 4-6°C in summer field tests while maintaining natural daylight transmission.

5. Application Case Study 3: LED Lighting Transparent Colored Lampshades

A LED lighting manufacturer required transparent amber coloring on polycarbonate (PC) lampshades for automotive signal lighting, demanding precise chromaticity coordinates, high light output efficiency, and thermal stability. DENSON high transparency nano yellow colorant (nanoscale iron oxide yellow) at 1.8% loading was used in a PC injection molding-compatible transparent coating system.

Key performance: Chromaticity coordinates (x=0.50, y=0.47) meeting SAE J578 amber requirements, light transmittance 78% (550 nm), thermal stability 150°C/500h no discoloration, UV resistance QUV 1000h ΔE ≤ 2.0, impact retention ≥ 90% after coating. The nanoscale pigment distribution ensured uniform color across complex 3D lamp geometries with no flow marks or color gradients.

6. Key Selection Parameters and Usage Recommendations

| Application | Recommended Colorant Type | Typical Loading | Key Performance Metric |

| Cosmetics packaging | UV-curable nano colorant | 1.5-3% | Gloss ≥ 90 GU, ΔE ≤ 0.5 |

| Architectural glass | Silicone-acrylic nano colorant | 2-4% | VLT ≥ 65%, NIR block ≥ 70% |

| LED lighting | Heat-resistant nano colorant | 1-2.5% | Chromaticity tolerance ±0.01 |

Usage recommendations:

(1) For UV-curable systems, select colorants with UV-stable pigments (azo condensation, phthalocyanine, quinacridone) to prevent photodegradation during curing and service life.

(2) For glass coatings, ensure colorant compatibility with silicone resins by testing intercoat adhesion and thermal cycling (-20°C to 80°C).

(3) For plastic substrate coatings, evaluate colorant migration resistance using extraction testing (GB/T 28286-2012) to prevent contact staining.

(4) For detailed product specifications, consult DENSON technical data sheets (TDS) for each colorant grade.

7. Conclusion

The three application case studies demonstrate that DENSON high transparency nano colorants deliver superior transparent coloring performance across diverse industries: cosmetics packaging achieves high gloss and batch consistency with 40% lower pigment loading; architectural glass coatings combine 70% visible light transmittance with 75% NIR blocking for energy efficiency; and LED lighting meets precise automotive chromaticity requirements with excellent thermal stability. The nanoscale pigment dispersion technology enables these performance advantages while maintaining broad resin compatibility. Engineers should select colorant carrier systems and pigment types based on specific application requirements, curing conditions, and regulatory standards.

8. FAQ

Q1: Can high transparency nano colorants be used in food-contact packaging coatings?

A: Yes, provided the specific colorant grade uses pigments compliant with food-contact regulations such as GB 9685-2016 (China) or FDA 21 CFR 178.3297 (USA). DENSON offers food-contact-compliant nano colorant grades with migration testing documentation. Users should verify the specific grade's compliance status and intended use conditions (temperature, food type) before application.

Q2: How does nano colorant affect coating curing in UV systems?

A: Nano colorants can affect UV curing by absorbing UV light in the 200-400 nm range, potentially reducing photoinitiator efficiency. Carbon black and iron oxide pigments have stronger UV absorption than organic pigments. To ensure proper curing: use higher photoinitiator loading (1-3% additional), increase curing energy by 20-30%, select colorants with narrow particle size distribution to minimize scattering, and perform cure testing (MEK double rubs ≥ 100) before production.

Q3: What is the shelf life of high transparency nano colorants?

A: Under proper storage conditions (5-35°C, sealed containers, avoid direct sunlight), DENSON high transparency nano colorants have a shelf life of 12 months from production date. After opening, use within 3 months and reseal tightly. Colorants should be stirred thoroughly before use; if slight sedimentation occurs, high-speed dispersion (1000-1500 rpm / 10 min) can restore uniformity without affecting performance.

Q4: Can nano colorants be mixed with conventional colorants for color matching?

A: Yes, nano colorants are generally compatible with conventional colorants in the same resin system, but several precautions apply: (1) Ensure both colorants use compatible carrier systems (solvent-based with solvent-based, water-based with water-based); (2) Mix under low-to-medium shear to avoid dispersant desorption from nano particles; (3) Test storage stability of the mixed colorant formulation, as conventional pigment particles can act as nucleation sites for nano particle agglomeration; (4) Filter the final mixture through 200-400 mesh screen before application.

Q5: How do I troubleshoot haze formation in nano colorant coatings?

A: Haze in nano colorant coatings typically results from: (1) Pigment re-agglomeration due to incompatible resin or solvent - test compatibility and adjust solvent polarity; (2) Insufficient dispersion - increase dispersion time or use higher shear mixing; (3) Moisture contamination in solvent-based systems - ensure raw materials are dry; (4) Improper film thickness - maintain 15-25 μm dry film thickness. Diagnostic approach: measure coating haze with a hazemeter (GB/T 2410-2008), check pigment particle size via laser diffraction, and systematically vary formulation components to identify the root cause.