White Fused Alumina Micropowder for Rubber Fillers

I. Core Properties (Tailored for Rubber Applications)

• High Hardness & Wear Resistance: With a Mohs hardness of 9.0, it significantly reduces the wear rate of rubber and prolongs service life.
• High Purity & Whiteness: Al₂O₃ content ≥ 99.2%–99.7%, with extremely low impurities (Fe₂O₃ ≤ 0.06%), causing no contamination to light-colored rubber products.
• Chemical Inertness: Resistant to acids, alkalis, oils and solvents, with no reaction with rubber and additives.
• Excellent Thermal Stability: Melting point ~2050℃, enhancing the heat resistance, aging resistance and dimensional stability of rubber.
• Low Oil Absorption Value: ≤ 8%, ensuring good mixing processability and minimal impact on rubber compound viscosity.

II. Common Technical Specifications (Rubber Grade)

1. Particle Size (Key Selection Parameter)

• Coarse particles (enhanced wear resistance): white fused alumina 1000#–1500# (D50 ≈ 10–15μm) — for mine rubber linings, wear-resistant rubber sheets
• Medium particles (general reinforcement): 2000#–3000# (D50 ≈ 5–8μm) — for rubber rollers, seals
• Fine particles (smooth surface finish): 4000#–8000# (D50 ≈ 1–4μm) — for printing rubber rollers, precision gaskets

2. Typical Indicators

• Al₂O₃: ≥ 99.5%
• True density: 3.95–3.97 g/cm³
• Bulk density: 1.75–1.95 g/cm³
• pH value: 7–9 (neutral to weakly alkaline, compatible with most rubber systems)
• Magnetic substances: ≤ 20–30 ppm (to avoid equipment abrasion)

III. Main Functions in Rubber

• Greatly Improved Wear Resistance

  High-hardness particles form a wear-resistant framework to resist friction and impact, extending service life by 2–5 times. Applied in conveyor belts, hydrocyclone linings, pump and valve seals.

• Increased Hardness and Modulus of Elasticity

  Raises Shore hardness (A/D) with low compression set, suitable for high-pressure and load-bearing components (e.g., calendering rubber rollers).

• Enhanced Heat and Aging Resistance

  Blocks heat conduction and inhibits oxidative degradation, improving strength retention at high temperatures.

• Optimized Surface Performance

  Fine powder creates a denser and smoother surface, reducing friction coefficient and improving anti-blocking and cleanability (printing/textile rubber rollers).

• Strengthened Chemical Stability

  Resistant to acids, alkalis, oils and solvents, used in chemical anti-corrosion linings and sealing gaskets.

IV. Applicable Rubber Systems and Products

• Applicable rubber types: NR, SBR, NBR, EPDM, CR, silicone rubber, fluororubber (compatible with almost all systems)
• Typical products:
  • Industrial rubber rollers (printing, dyeing, papermaking, laminating)
  • Wear-resistant linings (mining, water conservancy, chemical equipment)
  • Seals, gaskets, diaphragms (high-pressure/corrosive conditions)
  • Wear-resistant conveyor belts, synchronous belts, friction blocks
  • Special rubber products (high temperature resistance, insulation, wear resistance)

V. Application Guidelines (Formulation and Processing)

• Dosage: 10–40 phr (20–30 phr commonly used for high-wear products)
• Surface Modification: Pretreatment with silane coupling agents (e.g., KH-550/560) is recommended to improve dispersion and bonding, and enhance tensile/tear strength.
• Mixing Process:
  1. First mix evenly with rubber during mastication
  2. Add in batches (to prevent agglomeration)
  3. Properly increase mixing temperature and time to ensure uniform dispersion