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):
- Assemble test stack: lower glass plate → filter paper → specimen face up → specimen face down → filter paper → upper glass plate.
- 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.
- 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.
