Overview
ISO 1435:1996 is the international standard that specifies a laboratory method for determining the fines content of pelletized (granulated) carbon black used in rubber compounding. Published in 1996 (fourth edition), it replaces the 1988 edition and describes the test that measures the fraction of a sample that will pass through a 125 µm nominal aperture sieve under defined mechanical shaking and hammering conditions.
Key Topics and Requirements
- Scope: Applicable to all types of pelletized carbon black for the rubber industry; determines percent fines (mass/mass).
- Sampling: Use a representative sample split by a stationary riffle/divider with at least six compartments (ISO 1124 referenced).
- Sample mass: Typical test portion 22–28 g; for denser blacks (apparent density ~600–650 kg/m³) use 47–53 g.
- Sieving equipment:
- Sieve: 125 µm nominal aperture, ~200 mm diameter, corrosion-resistant wire cloth in accordance with ISO 565.
- Mechanical shaker: Rotational-and-impaction shaker (e.g., Ro-Tap) mounted for a 200 mm sieve stack.
- Hammer/striking mechanism: Cork plug on lid protruding 3–9 mm; shaker should deliver ~280–320 rotary movements/min and ~140–160 hammer blows/min.
- Procedure: Weigh test portion accurately, sieve with the mechanical shaker while hammering for an agreed period (typical 5 minutes), then weigh material collected beneath the sieve.
- Result expression: Fines content = (mass passing the 125 µm sieve ÷ mass of test portion) × 100; report to 0.1% (m/m). Use a balance accurate to 1 mg.
- Precision: Short-term repeatability estimated at ±50% of result (relative) and reproducibility at ±97% (relative). No absolute bias can be established because the property is method-defined.
- Safety note: Users must follow laboratory safety and hygiene practices; the standard does not cover all safety aspects.
Applications and Who Uses It
- Quality control laboratories in rubber and tyre manufacturing
- Carbon black producers verifying pellet quality for shipment
- Procurement and QA teams specifying fines limits in material specifications
- Independent test laboratories offering conformity and material testing services
Practical benefits include consistent measurement of fines (which affect dispersion, mixing behavior, and handling) and a reproducible basis for supplier specifications and acceptance testing.
Related Standards
- ISO 1124 - Sampling procedures for carbon black deliveries
- ISO 565 - Standard reference for sieve aperture dimensions
Keywords: ISO 1435:1996, carbon black pelletized, fines content, 125 µm sieve, rubber compounding ingredients, Ro-Tap shaker, sieve analysis, quality control.
Open preview (PDF)Rubber compounding ingredients — Carbon black (pelletized) — Determination of fines content
