Are you searching for the safest and most efficient materials for food-related applications but unsure which rubbers to choose? Food-grade rubbers are indispensable in industries that demand high standards of cleanliness, durability, and compliance.
These specialised rubbers are designed to ensure safety, prevent contamination, and withstand demanding conditions in food processing and packaging. They offer useful benefits like temperature resistance, flexibility, and adherence to strict regulatory standards.
In this blog, we’ll explore the 6 best food-grade rubbers, their uses & common additives that improve their performance.
6 Best Food-Grade Rubbers, Their Uses & Common Additives
Food-grade rubbers are essential for maintaining safety, hygiene, and durability in food processing and packaging industries. Each type offers unique advantages customised for specific applications.
Below, we’ll explore the 6 best food-grade rubbers, their uses & common additives that improve their performance.
Natural Rubber
For aqueous foods at low temperatures
Natural rubber is commonly used in applications such as gloves, teats, and can sealants, especially under low-temperature conditions.
It’s also found in belting and hosing products in the food industry, though it’s gradually being replaced by alternatives like synthetic polyisoprene and silicone due to protein allergy concerns. Natural rubber can handle prolonged use up to 80°C but is typically used for short-term static or flow conditions below 40°C.
Nitrile Rubber
Better ageing up to 120°C
Nitrile rubber is well-suited for seals, gaskets, and hoses in contact with aqueous or fatty foods, including dairy applications like milk liners. It offers superior heat ageing properties compared to natural rubber, with a maximum continuous use temperature of 120°C. Most applications involve short-term static or flow exposure at temperatures below 40°C.
Ethylene-Propylene Rubber
For aqueous foods at higher temperatures
Ethylene-propylene rubbers (EPDM/EPM) are widely used in heat exchanger gaskets, offering durability at higher temperatures. When peroxide-cured, they can sustain prolonged exposure at up to 150°C. These rubbers are ideal for high-temperature applications involving aqueous food products like beer, typically under flow or static conditions.
Fluorocarbon Rubber
For prolonged use at high temperatures
Fluorocarbon rubbers (including copolymers and terpolymers) excel in high-temperature environments where other rubbers might degrade. They are used in gaskets for both static and flow conditions, withstanding temperatures up to 200°C. These rubbers are particularly suited for applications involving fatty foods and oils at temperatures below 150°C.
Silicone Rubber
For both high and low temperatures
Silicone rubbers, based on polydimethyl vinyl silicone, are known for their exceptional temperature resistance, making them ideal for seals and tubing in beverage vending machines and similar applications. They can endure high temperatures of up to 100°C and low temperatures without compromising performance. Silicone is also popular for food transportation belts and sweet moulds due to its cold curing and release properties.
Thermoplastic Elastomers
Versatile materials with limited temperature range
Thermoplastic elastomers (TPEs) are versatile materials crosslinked at room temperature and thermoplastic at processing temperatures above 150°C. They are commonly used in food contact products such as flexible lids, gaskets, and polyurethane tubing. However, their working temperature range is restricted to below 70°C due to their non-thermoset nature.
Other Types of Rubbers Used in the Food Industry
While the primary food-grade rubbers dominate the industry, other specialised rubbers are also utilised for niche applications. These materials address specific needs in food-related operations, ensuring versatility and efficiency.
Butyl Rubber
For stoppers and seals in aqueous food contact
Butyl rubber is widely used in the production of stoppers and seals that come into contact with aqueous foods. Its exceptional impermeability and flexibility make it a reliable choice for maintaining product integrity in these applications.
Polychloroprene Rubber
Perfect for conveyor belts in food transportation
Polychloroprene rubber is primarily used in conveyor belts for food transportation. Its durability, flexibility, and resistance to oils and weather conditions make it ideal for maintaining efficiency in food processing and handling.
Acrylic and Hydrin Rubbers
Specialty rubbers for challenging food contact conditions
Acrylic and Hydrin rubbers are selected for unique food contact conditions that demand specific properties, such as chemical inertness and moderate heat stability. These materials are used in specialised applications where standard food-grade rubbers may fall short.
Additives Used in Food Contact Rubbers
To achieve the desired processing and performance characteristics, various additives are used into food contact rubbers. These additives play crucial roles in improving properties such as flexibility, durability, and resistance to degradation, ensuring the rubbers meet industry standards.
Plasticisers/Process Oils and Fillers
Plasticisers and process oils are crucial in adjusting the mechanical properties of rubber compounds. They reduce hardness and tensile strength while improving flexibility and stretchability, making rubber more adaptable for specific applications.
Commonly used plasticisers include phthalates, adipates, sebacates, sulphonates, and hydrocarbon oils, each contributing to improved processing and material performance.
Fillers, in contrast, often increase viscosity and hardness while reducing flexibility. Carbon black is widely used as a primary filler to improve the strength and durability of rubber. Other fillers, such as silica and calcium carbonate, are employed to fine-tune properties or lower costs, providing a balanced approach to meet various application requirements.
Curatives and Antidegradants
Curatives are essential for achieving the desired properties in rubber, with sulfur and peroxides being the most common types. These substances ensure the material cures effectively, creating a durable and stable end product. Additional curatives like sulfur donors, amines, and metal oxides further improve the curing process, particularly for food contact rubbers.
Antidegradants are used to protect rubber from environmental degradation. Antioxidants, antiozonants, and UV stabilisers prevent damage from oxidation, ozone exposure, and sunlight. Available as staining (amines) or non-staining (phenolics) varieties, these antidegradants are often combined for maximum protection and longevity, ensuring the material remains reliable over time.
Miscellaneous Additives
Prevulcanisation inhibitors play a significant role in preventing premature curing during mixing and forming, maintaining the rubber's flexibility until the final curing stage. This ensures consistent processing and material quality. Coupling agents improve the interaction between fillers, such as silica, and the rubber matrix, optimising the overall performance of the compound.
Deactivators like polyethylene glycol prevent accelerators from being adsorbed onto polar fillers, maintaining consistent curing behaviour. Bonding agents strengthen the adhesion between fabric and rubber in composite products, ensuring durability and structural integrity in demanding applications. These specialised additives provide essential support for achieving high-performance rubber materials.
Conclusion
Food-grade rubbers play a crucial role in ensuring safety, durability, and compliance in food-related industries. From natural rubber and nitrile to silicone and thermoplastic elastomers, each material offers unique properties customised for specific applications.
Additives like plasticisers, fillers, curatives, and antidegradants further improve these rubbers, making them reliable and versatile for food contact use.
Understanding these materials and their properties is essential for selecting the best solution for your needs. At Reliant Rubber, we specialise in providing high-quality rubber products designed to meet the high standards of the food industry. Contact us today to discuss your needs and discover how our expertise can support your business.
Frequently Asked Questions
What are the best food-grade rubbers for industrial use?
The six best food-grade rubbers include natural rubber, nitrile rubber, ethylene-propylene rubber (EPDM), fluorocarbon rubber, silicone rubber, and thermoplastic elastomers (TPEs), each customised for specific applications.
Why is natural rubber used in the food industry?
Natural rubber is ideal for low-temperature applications involving aqueous foods, such as gloves, teats, and hosing with its flexibility and durability.
What makes nitrile rubber suitable for food-grade applications?
Nitrile rubber is resistant to heat aging and is widely used for seals, gaskets, and hoses, especially in dairy equipment like milk liners.
Why are antidegradants important in rubber products?
Antidegradants are crucial in rubber products as they protect against environmental damage like oxidation, ozone exposure, and UV radiation. Common types include amines (staining) and phenolics (non-staining), often combined for improved durability. Additional options like thioesters, phosphates, and waxes stabilise and extend rubber longevity.
What are thermoplastic elastomers, and where are they used?
Thermoplastic elastomers are versatile materials used in food contact products like flexible lids, gaskets, and tubing due to their rubber-like properties and ease of processing.
What additives are commonly used in food-grade rubbers?
Additives like plasticisers, fillers, curatives, and antidegradants are used to modify the mechanical properties, durability, and resistance of food-grade rubbers.
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