Overview
EN ISO 23900-2:2018 - Pigments and extenders: Methods of dispersion and assessment of dispersibility in plastics - Part 2 describes a standardized laboratory method to determine colouristic properties and the ease of dispersion (DH PVC‑P) of pigments in plasticized polyvinyl chloride (PVC‑P) using two‑roll milling. The method quantifies pigment performance by measuring changes in colour strength after controlled milling and photometric evaluation, enabling reproducible comparison of organic and inorganic pigments and pigment preparations.
Key topics and technical requirements
- Scope: Applicability to organic and inorganic black and colour pigments and pigment preparations dispersed in PVC‑P.
- Principle: Initial dispersion at (160 ± 5) °C on a two‑roll mill followed by further milling at (130 ± 5) °C; the increase in measured colour strength indicates the ease of dispersion (DH PVC‑P).
- Apparatus:
- Two‑roll mill with heating and adjustable roller spacing (recommended roll diameters ~80–200 mm and specific peripheral speed ratios).
- Plate press for producing test specimens.
- Photometer/colourimeter for quantitative colour measurements.
- Procedure highlights:
- Premixing of pigment with a defined basic compound (Annex A describes a recommended formulation).
- Controlled milling, pressing into sheets, and photometric measurement following ISO photometric methods.
- Suggested pigment/TiO2 ratios for routine checks: about 1:10 for organic pigments and 0.2–0.5:1 for inorganic pigments (for white reduction tests).
- Data and evaluation: DH PVC‑P is derived from differences in colour strength between the two milling conditions. Results are valid only for the specified dispersion equipment, conditions and medium.
Practical applications and users
- Who uses it: pigment manufacturers, plastics compounders, quality control and R&D laboratories, colour technologists, and formulators in PVC processing.
- Why use it:
- Compare dispersibility and colouristic performance of pigments for PVC products.
- Routine quality control and supplier acceptance testing.
- Support product development, color matching and process optimisation in PVC compounds.
- Generate reproducible photometric data for specifications and material dossiers.
Related standards
- ISO 23900 series (Part 1 general introduction; Parts 3–6 covering other plastics and test methods)
- ISO 787-24 (photometric methods for tinting strength)
- ISO 15528 (sampling)
- ISO 18314-1 (analytical colorimetry)
- EN 12877-1 (colour stability during processing)
EN ISO 23900-2:2018 provides a practical, standardized lab protocol for assessing pigment dispersibility and colour performance in plasticized PVC, supporting consistent QC, benchmarking and formulation decisions in the pigments and plastics industries.