Overview
ISO 7664:2000 provides general guidance on storage of raw natural and raw synthetic rubber delivered in the form of bales. The standard identifies the environmental and handling factors that influence rubber quality in storage and gives practical guidance to minimize deterioration such as hardening, softening, surface degradation, discolouration and crystallization. It also warns that particulate rubber (powder, loose crumb, pellets) requires extra care due to greater exposed surface area and the risk of agglomeration under elevated temperature or pressure.
Key Topics and Requirements
- Storage accommodation
- Store rubber in a clean, dry, well-ventilated space at a moderate temperature.
- Temperature
- Preferably between 10 °C and 35 °C; however, real-world conditions may vary by location.
- Note: crystallization of natural rubber is fastest near ≈27 °C and rapid between 0 °C and 10 °C. A minimum storage temperature of 20 °C is recommended to limit crystallization where applicable.
- Crystallization is reversible: raise temperature before processing to restore workability.
- Heating
- Arrange heat sources and screening so the immediate vicinity of stored rubber does not exceed 25 °C.
- Humidity
- Avoid moist conditions and condensation on rubber or wrapping. Excess humidity can affect processing, cure behavior and may cause hydrolysis in some rubbers.
- Light protection
- Protect from direct sunlight and strong UV-rich artificial light. If packaging is not opaque, cover windows with a red or orange coating or screen; crates/pallets should be covered. Incandescent lamps are preferable to high-UV lighting.
- Contamination
- Keep rubber free from dust and foreign materials; avoid direct contact with other types of rubber. Keep rubber in original packaging until use and cover partially used packages.
- Stock rotation
- Use first in, first out (FIFO) to minimize storage time and preserve product quality.
Applications and Users
ISO 7664 is practical for:
- Rubber manufacturers and raw-material suppliers
- Warehouse and logistics managers handling rubber bales
- Quality assurance and production planners in rubber processing plants
- Procurement and storage facility designers specifying environmental controls
- Converters and compounders concerned with feedstock integrity
Implementing ISO 7664 guidance helps reduce product loss, ensure consistent processing behaviour and maintain vulcanizate quality.
Related Standards
ISO 7664 was prepared by ISO/TC 45 (Rubber and rubber products), Subcommittee SC 3 (raw materials). For handling, testing and specifications of raw rubber, consult other ISO documents from ISO/TC 45 and national standards applicable to packaging, transport and storage facilities.
