Overview
ISO 4659:2020 specifies an evaluation procedure for styrene‑butadiene rubber (SBR) masterbatches containing carbon black or carbon black plus oil. The standard defines the physical and chemical tests on raw rubbers, a standard test formulation, required equipment, and processing methods for assessing vulcanization characteristics and vulcanizate properties. It is intended for laboratory use in quality control, development and supplier evaluation of SBR masterbatches.
Key topics and requirements
- Sampling and preparation: Follow ISO 1795 for lot sampling and laboratory sample preparation.
- Raw‑rubber tests:
- Standard test formulation: A masterbatch-based recipe (masterbatch + zinc oxide, sulfur, stearic acid, TBBS accelerator) is provided to produce comparable test mixes. Carbon black (x) and oil (y) values refer to parts per 100 parts rubber in the masterbatch.
- Mixing and compounding procedures:
- Two mixing routes: Method A (laboratory mill) or Method B (single‑stage laboratory internal mixer - preferred).
- Specified roll and mixer temperatures, batch masses, and mixing times to ensure reproducible dispersion.
- Post‑mix storage/conditioning recommendations (2 h to 24 h) per ISO 23529.
- Vulcanization evaluation:
- Curemeter tests using an oscillating‑disc curemeter (ISO 6502‑2) or rotorless curemeter to measure cure curves and parameters (minimum/maximum torque, t'50, t'90) under specified conditions (e.g., die temperature 160 °C).
- Warning on possible nitrosamine formation - follow lab safety practices.
- Physical testing: Tensile stress‑strain properties of vulcanized test mixes per ISO 37.
- Precision and reporting: Requirements for test precision and information to include in test reports.
Applications and users
ISO 4659:2020 is used for:
- Quality control and acceptance testing of SBR masterbatches (carbon black or carbon black + oil).
- R&D and formulation development to compare vulcanization behavior and mechanical performance.
- Supplier qualification, production troubleshooting, and benchmarking of masterbatch performance.
Primary users include rubber compounders, masterbatch manufacturers, tyre and rubber goods producers, independent testing laboratories, and materials engineers.
Related standards
Commonly used in conjunction with:
Keywords: ISO 4659:2020, styrene‑butadiene rubber, SBR masterbatch, carbon black, curemeter, Mooney viscosity, vulcanization characteristics, rubber testing.