ISO 23900-4:2015

Overview

ISO 23900-4:2015 is an international standard developed by ISO that specifies a precise method for determining the colouristic properties and ease of dispersion of white pigments in polyethylene (PE). This standard focuses on dispersing pigments using a two-roll milling process and evaluates pigment performance by comparing test samples with standards. Key metrics include tinting strength and dispersion efficiency, which are critical for manufacturers and quality controllers in plastics and pigment industries aiming to ensure consistent color quality and pigment behavior in polymer applications.

Key Topics

• Scope and Purpose
  ISO 23900-4:2015 is designed for testing white pigments dispersed in polyethylene. It provides a standardized way to measure pigment colouristic properties and the ease of dispersion, denoted as DH_PE, based on changes in tinting strength under controlled milling conditions.

• Test Procedure

  • Preparation of pigment-polyethylene mixtures with carbon black masterbatch
  • Dispersion on heated two-roll mills with adjustable roller gaps (0.5 mm and 0.3 mm) to simulate different shear forces
  • Pressing milled sheets into test samples suitable for photometric measurement
  • Photometric evaluation to determine tinting strength changes, which are used to calculate ease of dispersion

• Materials and Equipment

  • Polyethylene and carbon black polyethylene masterbatch as base materials
  • Two-roll mill with specific temperature control and roller speed ratios (between 1:1.1 and 1:1.2)
  • Photometer for colorimetric measurement
  • Plate press for preparing test specimens

• Evaluation Metric
  Ease of dispersion (DH_PE) is mathematically expressed as a percentage increase in tinting strength when the pigment-polymer composite is milled at a narrower gap (0.3 mm) compared to a larger gap (0.5 mm). This measurement reflects how readily pigments disperse under shear.

• Reporting and Accuracy
  The standard outlines the essential information to be included in test reports to ensure reproducibility and transparency. It also notes that precision depends on the equipment and materials used, requiring laboratories to conduct repeatability and reproducibility assessments internally.

Applications

ISO 23900-4:2015 is vital for industries and professionals involved in:

• Plastic Manufacturing
  Ensuring consistent coloration and optimal dispersion of white pigments in polyethylene products such as films, containers, and molded parts.

• Pigment Quality Control
  Assessing and comparing pigment batches to maintain uniform dispersibility and performance characteristics.

• R&D for New Pigments
  Evaluating new titanium dioxide and other white pigments for integration in polymer systems.

• Material Compatibility Testing
  Understanding pigment-polymer interactions impacting mechanical and aesthetic properties.

By applying this standardized test method, companies can achieve reliable pigment dispersion data essential for product quality, process optimization, and customer satisfaction in plastics production.

Related Standards

ISO 23900-4:2015 is part of a series of standards covering pigment dispersion and assessment in plastics:

• ISO 23900-1: General introduction to methods for pigment dispersibility
• ISO 23900-2: Method for plasticized polyvinyl chloride using two-roll milling
• ISO 23900-3: Determination of dispersion for black and coloured pigments in polyethylene
• ISO 23900-5: Dispersion testing by filter pressure value method
• ISO 23900-6: Dispersion testing by film test method

Additional normative references integrated within ISO 23900-4 include:

• ISO 787-24: Photometric methods for tinting strength and scattering power of pigments
• ISO 15528: Sampling protocols for paints and raw materials
• ISO 18314-1: Practical colour measurement techniques for analytical colorimetry

Together, these standards provide a comprehensive toolkit for pigment and extender dispersion evaluation across diverse polymers and pigment types.

Keywords: ISO 23900-4, pigment dispersibility, white pigments, polyethylene, two-roll milling, tinting strength, ease of dispersion, pigment testing standard, plastic coloration, pigment quality control, polymer additives.