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Applications · Rubber

TiO2 for Rubber & Tire Sidewall

White rubber compounds — anatase for soft crystal, low equipment wear; rutile for outdoor service.

White rubber compounds are used in tire sidewalls (decorative white stripe), EPDM weather strips, conveyor belts in food/pharma processing, white hoses, and various consumer rubber goods. The TiO2 in these applications provides white opacity in a high-mechanical-shear rubber compound that goes through Banbury mixing, extrusion, and vulcanization.

For most rubber applications, SEMITI A200 anatase is the preferred grade — soft crystal hardness means less wear on Banbury mixer rotors and extruder dies. For outdoor-exposed applications (premium tire sidewall, EPDM in exterior service), SEMITI 996 or 2310 rutile is acceptable but extruder wear is meaningfully higher.

Performance requirements

Tinting strength after Banbury mixingNo measurable loss after standard cycle
Compatibility with sulfur curingNo interference with vulcanization at 145–165°C
Heat aging (100°C / 70 hr)Tensile retention > 80%
UV resistance (limited outdoor)Chalking < grade 3 (ASTM D4214) after 1 year outdoor

Dosage guidance

White tire sidewall: 5–15 phr TiO2 + zinc oxide + amine antioxidant. EPDM weather strip: 3–8 phr. White conveyor belt (food/pharma): 8–15 phr. Decorative rubber goods: 5–10 phr.

Dispersion / processing notes

Standard Banbury intensive mixer (200 L+ chamber) at 80–120°C, 60–90 rpm rotor speed. Add TiO2 with the curative package or earlier with the carbon black masterbatch (if any). Output is sheeted, cooled, and either extruded direct or pelletized for downstream forming.

Formulation tips

  • Use SEMITI A200 (anatase) for tire sidewall — soft crystal means longer Banbury rotor life
  • Pair with ZnO + amine antioxidant for sulfur vulcanization in NR / IR / IIR systems
  • For outdoor EPDM (window seals, automotive trim), accept the equipment wear penalty and use SEMITI 996 rutile
  • Premium white rubber (food-grade conveyor belt) demands FDA-compliant TiO2 — both A100 and A200 meet FDA 21 CFR 178.3297

Common pitfalls

Failure modes we've seen in customer trials — worth checking before scale-up.

  • ×Using rutile in indoor / short-service rubber — pays equipment wear premium without performance benefit
  • ×Skipping the antioxidant package — TiO2 alone doesn't protect rubber from oxidation
  • ×Using nano TiO2 (SEMITI NANO-30) in rubber — only for personal care, not rubber

Common questions

Why anatase vs rutile for tire sidewall?+
Anatase has Mohs hardness 5.5–6 vs rutile 6–6.5. The 0.5-point difference translates to ~30% less wear on Banbury rotors and extruder dies. Tire sidewall service life is 5 years (matched to tire), so anatase's lower outdoor durability isn't a service-life issue.
Is TiO2 used in tire tread?+
No — tread is reinforced with carbon black (for performance) or silica (for fuel-efficient tires). TiO2 only appears in the decorative white sidewall stripe.

Need help picking a grade for rubber & tire sidewall?

Send us your reference grade, formulation type, or competitor TDS. We'll respond with the SEMITI match + sample within 48 hours.