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Nano-dispersion Technology
Overcoming the agglomeration bottleneck of traditional titanium dioxide, the particle size of titanium dioxide and other powders is precisely controlled at 0.2–0.4 µm. By uniformly dispersing these particles within the PE resin carrier, light scattering efficiency is maximized, ensuring high opacity, gloss, and stability. Extremely low coarse-particle residue helps eliminate screen clogging and surface defects.
Industry Reference · Pigmentary TiO₂
Plastic-Grade Rutile TiO₂ — Particle Size Distribution
For high-quality plastic-grade rutile titanium dioxide, particle size sits in the narrow window that maximizes white-light scattering. The optimum is around 250 nm, with the bulk of the distribution falling between 0.15 µm and 0.50 µm. A narrow, well-controlled distribution is what separates premium grades from commodity grades.
D10
0.18 µm
10% of particles are smaller than this size — small-end of the primary particle distribution
D50 · Median
0.28 µm
Median particle size — sits at the optimum for visible-light scattering (≈ 250–280 nm)
D90
0.45 µm
90% of particles are smaller than this size — well-dispersed, no large agglomerates
Frequency Distribution (Density Curve)
Volume-weighted frequency vs particle size. Peak ≈ 0.27 µm — the optimal size for scattering visible light. Distribution shape: log-normal, geometric σ ≈ 0.36.
Volume frequency (%)
D10 = 0.18 µm
D50 = 0.28 µm
D90 = 0.45 µm
Cumulative Distribution (S-Curve)
Cumulative volume percent under a given size. D10, D50, D90 can be read directly off the horizontal lines at 10%, 50%, and 90%.
Cumulative volume (%)
D10 intercept
D50 intercept
D90 intercept
Why This Distribution Matters for Plastics
Particle size sets the optical and processing performance of a pigment. For plastics applications, the industry has converged on a narrow window for very specific reasons.
The 250 nm Optimum
Light scattering in the visible range (400–700 nm) is maximized when the pigment particle diameter is roughly half the wavelength of light — about 200–300 nm. Particles smaller than ~150 nm scatter too little visible light (they appear translucent); particles larger than ~500 nm scatter less efficiently per gram and begin to affect surface gloss and film quality.
That is why high-quality plastic-grade rutile pigments are engineered to a D50 between 0.25 and 0.30 µm.
Why a Narrow Distribution Matters
A narrow distribution (small span = (D90 − D10) / D50) gives more consistent opacity, color, and dispersion behavior. For the values shown here:
- Span = (0.45 − 0.18) / 0.28 ≈ 0.96
- Fine fraction (D10) at 0.18 µm — minimal sub-optical particles
- Coarse fraction (D90) at 0.45 µm — no large agglomerates that would reduce gloss
Commodity grades typically show a span of 1.3–1.8 with D90 values above 0.6 µm, which translates into reduced tinting strength and visible specks in thin films.
Sources & references:
typical pigmentary rutile crystal size ≈ 0.25 µm
(HORIBA Scientific);
optimum scattering at ≈ 250 nm and typical plastic-grade range 0.15–0.30 µm
(Malvern Panalytical Mastersizer 3000 application note);
premium-grade mean ≈ 0.27 µm and importance of narrow distribution
(HX TiO₂ Dispersibility Guide);
conventional rutile range 0.25–0.35 µm
(NB Inno Technical Article).
Test Results
Fineness of Grind — DW-1070
Hegman fineness and 45 µm sieve residue results — both measured per ISO 1524.
| Item | Test Method | Specification | Test Result |
|---|---|---|---|
|
Hegman Fineness
Hegman gauge reading
|
ISO 1524 | ≥ 6 | ✓ 6.5 |
|
Residue on 45 µm Sieve
Coarse particle content
|
ISO 1524 | < 0.02 % | ✓ < 0.018 % |