Overview
ISO 706:2004 - Rubber latex - Determination of coagulum content (sieve residue) - specifies a laboratory test method for measuring the coagulum content (sieve residue) of natural rubber latex concentrate and most synthetic rubber latices. The standard defines the sampling and test procedure, the required apparatus and reagents, and how to express results. It is not suitable for XSBR latices intended for paper-coating applications (see Annex A).
Key topics and requirements
- Scope and applicability: Applies to natural rubber latex concentrates and the majority of synthetic latices; excludes XSBR for paper coating unless agreed otherwise.
- Sampling: Laboratory samples must be prepared according to ISO 123 and must exclude dried latex skin and gross coagulum.
- Test filters / sieves:
- A coarse pre-filter (nominal aperture ~710 µm) is used to remove large particles.
- The test filter is stainless-steel wire cloth with an average aperture of 180 µm ± 10 µm (ISO 3310-1 compliant).
- Reagents: Use distilled water and analytical-grade reagents. Surfactants specified:
- Anionic surfactant (potassium oleate or ammonium laurate) for natural rubber latices.
- Non‑ionic ethoxylated alkylphenol for synthetic latices.
- Procedure (summary):
- Strain sample through 710 µm filter; weigh a defined test portion (~200 g).
- Mix with specified surfactant, pour through the 180 µm test filter, rinse until washings are clear.
- Dry filter plus residue to constant mass at ~100 °C and weigh.
- Result expression: Coagulum content (%) = (m2 − m1) / m0 × 100, where m0 = test portion mass, m1 = empty test filter mass, m2 = filter + dried coagulum mass.
- Precision and quality: Precision was evaluated via an interlaboratory study (13 labs); users should consult ISO/TR 9272 for precision terminology and statistical details. Duplicate determinations are required and criteria for repeatability are specified.
Applications
- Quality control and acceptance testing of natural rubber latex concentrates and many synthetic latices used in:
- Dipping, foam production, adhesives, and rubber product manufacture.
- Supplier and buyer specifications for latex shipments and bulk deliveries.
- NOTE: For high-speed paper-coating operations, finer filtration (e.g., ~44 µm) is necessary - ISO 706’s 180 µm criterion may not be sufficient.
Who should use this standard
- Latex producers and processors
- Quality control and materials testing laboratories
- Rubber product manufacturers and procurement specialists
- Standards and compliance officers in the rubber and coatings industries
Related standards
Keywords: ISO 706:2004, rubber latex, coagulum content, sieve residue, test method, 180 µm sieve, natural rubber latex, synthetic latex, latex quality control.
