Titanium Dioxide for Plastics: Grade Selection and Performance Data
"A masterbatch producer once told me he'd used the same rutile grade for five years. When we tested alternatives, we found a grade that dispersed 30% faster and saved $45/MT. Five years of leaving money on the table."
TL;DR — Key Takeaways:
Why TiOâ‚‚ Matters in Plastics
TiOâ‚‚ provides whiteness, opacity, UV protection, and visual appeal in plastics. The global plastics industry consumes ~35-40% of all TiOâ‚‚ produced. Market split: masterbatch (45%), PVC profiles/pipes (25%), packaging films (15%), engineering plastics (10%), other (5%). Three parameters consistently determine success: dispersion quality, yellowness index, and UV durability.
6 Key Parameters for Plastics Grades
|
Parameter |
Target |
Why It Matters |
|
TiOâ‚‚ Content |
≥92% (rutile) |
More pigment per kg, but surface treatment matters too |
|
Yellowness Index (YI) |
≤3.0 (premium), ≤5.0 (standard) |
High YI requires blue toner compensation — adds cost |
|
Dispersion (Hegman) |
≥7.0 (film), ≥6.0 (profile) |
≥30خ¼m agglomerates cause visible defects |
|
Volatiles at 105آ°C |
≤0.5% |
Moisture causes bubbles and splay marks |
|
Oil Absorption |
16-22 g/100g |
Lower = higher loading in masterbatch |
|
Residue on 45خ¼m |
≤0.02% (premium), ≤0.05% (standard) |
Coarse particles cause die buildup |
Cost Saving Case: A PP nonwoven fabric producer was rejecting 3% of production due to TiO₂ agglomerates. Switching to finer-dispersion rutile reduced rejections to 0.3% — saving ~$120,000/year on a 5,000 MT line.
Rutile vs Anatase for Plastics
Rutile is the correct choice for virtually all plastic applications. Anatase accounts for <5% of plastics TiOâ‚‚ use. Rutile provides: 20-30% higher opacity, essential UV protection (PVC profiles with rutile last 15-25 years vs 3-5 years with anatase), and better color stability. Anatase is only used for strictly indoor applications (disposable tableware), when a blue undertone is desired, or when cost saving outweighs performance (indoor only). My rule: If your plastic sees sunlight even incidentally, specify rutile.
Surface Treatment in Plastics
Inorganic coatings (silica, alumina): Provide UV durability. All plastics-grade rutile should have alumina at minimum. Outdoor applications need silica+alumina dual coating.
Organic after-treatments (polyols, siloxanes): This is the real differentiator. Organic-treated grades disperse 40-60% faster in polyolefin twin-screw extruders. Directly translates to higher throughput and lower energy cost.
Specialized treatments: For ABS, PC, and nylon, tailor-made organic treatments improve compatibility at high temperatures. Premium grades command a price premium but deliver measurably better results.
|
Plastic Type |
Recommended Treatment |
Key Benefit |
|
PVC (rigid) |
Alumina, or Silica+Alumina for outdoor |
UV durability |
|
PE/PP Masterbatch |
Alumina + organic treatment |
Fast dispersion, high loading |
|
ABS/PS |
Alumina + heat-stable organic |
Thermal stability |
|
Engineering Plastics |
Specialized organic treatment |
Compatibility |
Grade Selection by Plastic Type
PVC Profiles & Pipes — Silica+alumina rutile (DR-2588, R-2196). 4-6 phr for profiles, 2-4% for pipes. Key spec: TiO₂ ≥92%, YI ≤4.0, residue ≤0.02%.
Masterbatch (PE, PP, PS) — Organic-treated rutile (R-251, DR-2589). Loading 50-65% in concentrate. Key spec: Hegman ≥7.0, oil abs ≤20, YI ≤3.0.
Packaging Film (BOPP, LDPE) — Fine particle rutile (R-251). Loading 6-10%. Key spec: Hegman ≥7.5, residue ≤0.01%, volatiles ≤0.3%.
Engineering Plastics (ABS, PC, PBT) — Heat-stable rutile (CR-758). Processing 220-300آ°C. Key spec: YI ≤3.0 after 300آ°C/10min aging test.
Biodegradable Plastics (PLA, PBAT) — Low-moisture rutile. Key spec: volatiles ≤0.3%, pH 6.5-7.5.
Optimal TiOâ‚‚ Loading
|
Application |
Loading |
Opacity |
|
PVC window profile |
4-6 phr |
95-98% at 2mm |
|
Masterbatch (50:1) |
50-65% in conc. |
98%+ at 30خ¼m |
|
BOPP film |
6-10% final |
92-96% at 20خ¼m |
|
ABS housing |
4-8% |
Full hiding at 1.5mm |
|
White pipe |
2-4% |
85-92% |
Tip: Test 3-4 loading levels to find the "knee point" — where more TiO₂ stops delivering noticeable opacity improvement. Often at 4-5% for non-film applications.
Real-World Case: A pipe manufacturer in Egypt was using 8% TiOâ‚‚ ("what we've always done"). Loading curve showed 4.5% achieved 90% of the whiteness at 56% of the TiOâ‚‚ cost. Annual savings: $180,000.
4-Step Testing Protocol
Step 1: Filter pressure test (1h). Measure pressure increase over time with fine filter pack (15-20خ¼m). Stable = good dispersion. Increase >15% = red flag.
Step 2: Color measurement (30min). Measure CIE L*a*b* relative to reference. Target خ”E
Step 3: Dispersion microscopy (1-2h). Thin sections (10-20خ¼m) at 100x. Count agglomerates >30خ¼m: target 0-2 per mmآ².
Step 4: Weathering (500-1,000h, optional). Per ISO 4892. Target خ”E
Frequently Asked Questions
Q: Best TiOâ‚‚ loading for general-purpose white masterbatch (50:1 letdown)?
A: 55-60% TiOâ‚‚. Above 65% melt flow becomes difficult. Organic-treated grades can reach 70% with acceptable processing.
Q: Same TiOâ‚‚ for film and injection molding?
A: Not optimal. Film needs Hegman ≥7.5; injection can work with ≥6.0. Using injection-grade in film risks defects.
Q: Why does TiOâ‚‚ yellow in ABS?
A: Grade not heat-stabilized for 220-260آ°C processing. Trace catalytic impurities accelerate polymer degradation. Specify heat-stabilized grades.
Q: Does TiOâ‚‚ affect mechanical properties?
A: Yes — poorly dispersed TiO₂ reduces impact strength by 20-40%. With proper dispersion, reduction is <10%. Always test mechanical properties when switching grades.
Q: Chinese vs Western TiOâ‚‚ brands for plastics?
A: Chinese rutile has closed the quality gap since 2020. Mid-range grades (R-251, DR-2589) offer comparable performance at 15-25% lower cost. For medical/food/automotive, established chloride-process brands still lead in batch consistency.
Need the right TiOâ‚‚ grade for your plastic application?