Overview
ISO 4612:2018 - Plastics - Preparation of PVC pastes for test purposes - Planetary-mixer method describes two standardized procedures (Method A and Method B) for preparing PVC pastes (plastisols) using a planetary mixer. The standard covers required apparatus, sample conditioning, step-by-step mixing sequences, temperature checks, de-aeration and reporting. Prepared pastes are intended for laboratory test purposes, notably the determination of rheological properties used in resin designation and specification.
Key topics and requirements
- Two mixing methods
- Method A (single-speed): Designed for resins prone to heat build-up. Fixed-speed mixing with a longer total mixing time (specified in the standard).
- Method B (two-speed): Faster, two‑speed procedure suited to repetitive process-control work; shorter total mixing time.
- Planetary mixer specifications
- Stainless-steel mixing bowl (manufacturer recommended fill level to allow efficient mixing for typical charges).
- Beater/bowl configuration and fixed speed ratio between beat rotation and orbital motion (manufacturer set; approximate ratio provided in the standard).
- Optional features: cooling jacket, rotating wiper/scraper, vacuum capability.
- Process controls
- Preconditioning of PVC resin to 23 °C ± 2 °C and (50 ± 5) % RH (per ISO 291) before use.
- Order of addition: resin, then plasticizer, with other powders or liquids added according to formulation guidance.
- Defined mixing speeds, timed scrape-downs or continuous mixing if a rotating scraper is fitted.
- Immediate temperature check after mixing; if paste temperature exceeds the limit given in the standard, corrective actions are required (cooling, more plasticizer, or alternative method).
- De-aeration of paste under partial vacuum and storage at controlled atmosphere until testing.
- Documentation
- The paste-preparation report must reference ISO 4612:2018, include formulation, paste temperature on completion, preparation date and any deviations.
Applications and users
- Applications
- Preparation of laboratory PVC pastes (plastisols) for rheological testing, quality control, resin designation and specification.
- Development and comparison of PVC resins, plasticizers and additives under repeatable, standardized conditions.
- Who benefits
- PVC resin manufacturers, laboratory technicians, R&D and quality-control teams, standards and testing laboratories, and formulators of plastisols and PVC-based coatings or products.
Related standards
- ISO 291 (conditioning for plastics testing) - referenced for atmospheric conditioning prior to paste preparation.
- Prepared by ISO/TC 61 Plastics, Subcommittee SC 9 (Thermoplastic materials).
Keywords: ISO 4612:2018, PVC pastes, plastisols, planetary mixer, paste preparation, mixing method, rheological properties, PVC resin, paste de-aeration.