Overview
ISO 22751:2020 specifies a standardized laboratory method to determine the bending force of rubber- or plastic-coated textile fabrics. The method uses a bar / two‑point bending arrangement in which a sample is clamped and rotated against a vertical bar while a force transducer records the force developed at specified angles. The standard defines apparatus, sampling, conditioning, test parameters and result reporting to ensure repeatable, comparable bending measurements for coated textile supports.
Key topics and requirements
- Test principle: bar (two‑point) bending - sample fixed in a rotatable clamp presses against a vertical bar; force measured as a function of bending angle.
- Apparatus:
- Clamp depth (35 ± 1) mm and minimum clamp width ≥ 30 mm; pivot axis located on the front edge of the fixed jaw (±0.1 mm).
- Rotation range 1°–91°, speed adjustable up to 10°/s (accuracy 0.1°/s; 1% max deviation at load).
- Force sensor capable up to 10 N (optionally 1 N for very soft materials) with accuracy per ISO 7500‑1 class 2; sensor axis horizontal.
- Measuring bar edge radius R = 0.05 ± 0.01 mm, bar width ≥ 30 mm. Distance from pivot to bar adjustable 0.1–50 mm (accuracy 0.1 mm).
- Pre‑load (preliminary force) adjustable with ≥1 mN resolution; recommended electronic archiving of raw data and parameters.
- Sample preparation & sampling:
- At least three specimens parallel and three perpendicular to manufacturing direction; sample sizes depend on chosen parameter set (see Table 1: flexion lengths 5/10/15 mm; free lengths 15/20/25 mm; measurement angle 60°; flexion to 63°; speed 1.5°/s; preliminary force 3 mN).
- Mark face to be pressed against bar; test each specimen only once.
- Conditioning & test atmosphere:
- Follow ISO 2231 conditioning; minimum exposure 16 h for single‑sided, 24 h for double‑sided coated supports. Test atmospheres chosen from ISO 2231 (A–E), typically 23 °C (temperate) or 27 °C (tropical).
- Thickness: measure according to ISO 2286‑3, preferably after bending test.
- Results: express bending force in millinewtons (mN) with three significant figures; report means across sampling directions and, if applicable, for extension and compression.
Applications and users
ISO 22751 is used to:
- Characterize flexibility and handle of coated textile products (PVC‑coated fabric, rubber‑coated textiles).
- Compare materials for upholstery, tarpaulins, protective clothing, inflatable structures, conveyor belting facing, and technical textiles where bending behavior affects performance or processing.
Primary users:
- Textile and rubber test laboratories
- Material suppliers and processors
- Product designers and quality/control engineers
- Standards bodies and certification organizations
Related standards
- ISO 2231 - conditioning atmospheres
- ISO 2286‑3 - thickness measurement for coated textiles
- ISO 7500‑1 - calibration/verification of force measuring systems
Keywords: ISO 22751, bending force, rubber-coated fabrics, plastic-coated fabrics, bar bending test, coated textile testing, flexion test, test method.