ISO 5978:2023

Overview

ISO 5978:2023 specifies a laboratory method to determine the blocking resistance of rubber- or plastics-coated fabric sheets when left in contact under defined temperature, time and pressure. The standard provides repeatable procedures, conditioning requirements and a simple rating scale to assess whether coated surfaces will adhere (block) in storage or processing environments.

Key Topics

• Scope: Method for assessing resistance to unintentional adherence (blocking) of coated fabrics.
• Samples: Six test specimens, each (150 ± 2) mm × (150 ± 2) mm, taken from the working width and at least 100 mm from the edge of the sample.
• Conditioning: Test specimens, glass plates and filter-paper interlayers are conditioned in a standard atmosphere per ISO 2231 (climate B recommended) for at least 24 h.
• Apparatus:
  • Lower glass plate: minimum 153 mm × 153 mm, ~3 mm thick.
  • Upper glass plate: (155 ± 2) mm × (155 ± 2) mm, ~3 mm thick.
  • Strips of filter paper: (160 ± 2) mm × (160 ± 2) mm (used between specimen and glass plates).
  • Weight piece: mass (5,0 ± 0,1) kg (selected to exert nominal pressure (2,18 ± 0,02) kPa if specimen dimensions vary).
  • Circulating-air oven capable of (70 ± 2) °C (standard) and providing at least six air changes per hour.
• Procedure (summary):
  1. Assemble test stack: lower glass plate → filter paper → specimen face up → specimen face down → filter paper → upper glass plate.
  2. Place assembly in pre-heated oven and load centrally with the weight piece to apply the specified pressure. Standard test conditions: 70 ± 2 °C for 3 h, unless otherwise specified.
  3. Remove assemblies, cool in the standard atmosphere for 1 h, then separate and inspect for adherence or peeling.
• Rating scale (8.4): No blocking, Slight blocking, Blocking (coating damaged or removed).
• Timing constraints: Minimum 16 h between manufacture and testing; non-product tests: maximum 4 weeks; product tests: preferably within 3 months (other delivery-related constraints noted in the standard).

Applications

• Quality control for coated fabric manufacturing and storage
• Comparative evaluation of coating formulations and processing conditions
• Verification of handling and conversion parameters where elevated-temperature contact may occur

Related Standards

• ISO 2231 - Standard atmospheres for conditioning and testing (referenced for specimen conditioning)
• ISO 5978:1990 - Previous edition cancelled and technically revised by ISO 5978:2023

Practical value: Implementing ISO 5978:2023 helps manufacturers and converters identify blocking risks, improve coating formulations and specify safe storage/processing conditions to maintain product integrity and processing reliability.