Platinum-Cured Silicone Rubber in Food-Grade Applications

Platinum-cured silicone rubber is widely used in food-grade and hygienic applications due to its purity, stability, and excellent resistance to temperature and chemicals. Compared to peroxide-cured systems, platinum curing (also known as addition curing) produces a cleaner elastomer with superior performance characteristics, making it the preferred choice where food contact compliance is critical.

What Is Platinum-Cured Silicone Rubber?

Platinum-cured silicone rubber is crosslinked through an addition-cure reaction using a platinum catalyst. This curing mechanism does not produce by-products such as peroxides or decomposition residues, resulting in a highly pure elastomer network.

Because no volatile by-products are generated, platinum-cured silicones exhibit low extractables, minimal odour, and excellent long-term stability, all of which are essential for food-contact applications.

Key Properties for Food-Grade Use

1. High Purity and Low Extractables

The absence of curing by-products significantly reduces the risk of taste, odour, or contamination transfer. This makes platinum-cured silicone ideal for applications involving repeated or prolonged food contact.

2. Wide Temperature Resistance

Platinum-cured silicone rubber maintains stable mechanical properties across a wide temperature range, typically from –60 °C to +200 °C, with short-term exposure to higher temperatures possible. This is particularly important for applications involving hot liquids, steam, or cleaning cycles.

3. Excellent Chemical and Moisture Resistance

Silicone rubber offers outstanding resistance to water, steam, and many food-related chemicals, including fats, oils, and mild cleaning agents. This ensures durability and dimensional stability during service and wash-down processes.

4. Mechanical Performance and Elastic Recovery

Platinum-cured systems generally provide superior elastic recovery, compression set resistance, and long-term ageing performance compared to peroxide-cured alternatives. These properties are critical for seals, gaskets, and tubing that must maintain performance over extended service life.

Compliance with Food-Contact Regulations

Platinum-cured silicone rubber is commonly formulated to comply with major international food-contact standards, including:

• FDA 21 CFR 177.2600 (Rubber articles intended for repeated food contact)

• EU Framework Regulation (EC) No. 1935/2004

• German BfR Recommendation XV

• USP Class VI (for applicable grades)

Compliance depends on the specific formulation, raw materials, and processing controls, making supplier validation and documentation essential.

Processing Considerations

Platinum-cured silicone rubbers are sensitive to catalyst poisoning from substances such as sulphur, amines, organotin compounds, and certain pigments. Strict control of raw materials, tooling cleanliness, and processing environments is required to ensure consistent curing.

These materials are commonly processed via extrusion, compression moulding, injection moulding, and liquid silicone rubber (LSR) techniques. Post-curing is generally not required, although it may be used to further reduce volatiles in demanding applications.

Typical Food-Grade Applications

Platinum-cured silicone rubber is used extensively in:

• Food and beverage tubing

• Seals and gaskets for processing equipment

• Bakery moulds and conveyor components

• Dairy, beverage, and pharmaceutical transfer systems

• Valve seals and diaphragms

Conclusion

Platinum-cured silicone rubber offers a combination of purity, performance, and regulatory compliance that makes it ideally suited for food-grade applications. Its low extractables, excellent thermal stability, and long-term mechanical performance provide reliable service in demanding hygienic environments.

For manufacturers and processors where product integrity and compliance are critical, platinum-cured silicone remains a benchmark material choice.