ISO 23900-2:2015

Overview - ISO 23900-2:2015 (Pigments and extenders)

ISO 23900-2:2015 specifies a laboratory method for assessing the colouristic properties and ease of dispersion of pigments and pigment preparations in plasticized polyvinyl chloride (PVC‑P) using a two‑roll mill. The standard measures how much colour strength increases when a pigment is subjected to higher shearing (two‑stage milling), and expresses dispersibility as a percentage increase in colour strength (ease of dispersion, DH_PVC‑P). It is applicable to organic and inorganic colour and black pigments and to pigment preparations.

Key topics and technical requirements

• Two‑stage two‑roll milling:
  • Initial dispersion at (160 ± 5) °C to produce a milled sheet.
  • Secondary higher‑shear treatment at (130 ± 5) °C (sheet is folded and passed through the gap repeatedly).
• Sample preparation:
  • Premixing pigment with a recommended basic PVC‑P compound (Annex A) and forming sheets 0.4–0.5 mm thick.
  • Standard milling regime (mixing for a defined number of roll rotations, typical total 200 rotations) and cleaning between tests.
  • Pressing milled sheets (high‑gloss chrome plates, spacer ~1 mm) for photometric measurement.
• Photometric assessment:
  • Colour strength measured according to ISO 18314‑1 and ISO 787‑24 photometric methods.
  • Ease of dispersion (DH_PVC‑P) derived from the difference/ratio of colour strength values before and after the higher‑shear milling (see Clause 10.2).
• Reporting and traceability:
  • Test report must identify product, compound description, pigment concentration, photometric data, measurement method, equipment details (photometer, illuminant, observer), deviations and test date.
• Limitations:
  • Results are valid only for the specific equipment, dispersion conditions and compound used; different conditions can change absolute and comparative results.

Practical applications and users

• Pigment manufacturers - product development and batch quality control (QC).
• Plastics compounders and PVC processors - selection and specification of colouring materials for PVC products.
• Independent testing laboratories - comparative dispersibility testing and certification.
• Paint/coatings formulators and colorists - assessing tinting performance and dispersion behaviour in PVC matrices.
• Procurement and supply chain - defining supplier acceptance criteria and technical specifications.

Related standards

• ISO 23900 (series) - Parts 1, 3–6 (other dispersion and test methods)
• ISO 787‑24 - relative tinting strength and photometric methods
• ISO 18314‑1 - practical colour measurement (analytical colorimetry)
• ISO 15528 - sampling of paints and raw materials
• EN 12877‑1 - colouring materials in plastics (heat stability and processing)

Keywords: ISO 23900-2:2015, pigments, extenders, dispersibility, PVC‑P, two‑roll milling, colouristic properties, ease of dispersion, colour strength, photometric measurement.