Which material of supermarket trolley casters is more suitable for use in wet environments?

Recommended Supermarket Cart Caster Materials Suitable for Humid Environments
Humid environments (such as supermarket seafood areas, fresh produce washing areas, and cold chain thawing areas) can easily cause caster rubber to age and metal axles to rust. Therefore, materials with strong water resistance, corrosion resistance, and excellent anti-slip properties are preferred. After comprehensive comparison, ethylene propylene diene monomer (EPDM) and thermoplastic elastomers (TPE, specifically formulated) are the best choices. A detailed analysis is as follows:

1. First Choice: EPDM Casters
EPDM, with its molecular structure devoid of unsaturated double bonds and excellent chemical stability, is an ideal material for humid environments. Its core advantages are reflected in three aspects:
Extremely Water-Resistant and Aging-Resistant: EPDM is highly dense, making it difficult for water molecules to penetrate. Even with prolonged contact with stagnant water, the wheel surface will not become sticky, swell, or crack. It also resists mold growth, preventing mold growth in humid environments. It is also ozone- and UV-resistant. In humid and sunny environments, it ages at only one-fifth the rate of natural rubber, resulting in a service life of 8-10 years. months.
Anti-slip performance suitable for wet floors: EPDM casters can be formulated to increase the surface friction coefficient (wet floor friction coefficient ≥ 0.6). The "serrated + drainage groove" tread pattern quickly drains water between the wheel and the floor, reducing the risk of slipping. They are particularly suitable for use on slippery tile floors in aquatic areas.
Compatible with metal axle rust prevention requirements: EPDM casters are often equipped with galvanized or stainless steel axles (rather than ordinary iron axles). The metal components are highly rust-resistant, preventing axle rust and seizure caused by humid environments, further extending the overall service life.

2.  Water-Resistant Thermoplastic Elastomer (TPE) Casters
Ordinary TPE casters have average water resistance. It's best to choose a water-resistant TPE caster with an anti-hydrolysis agent and a high-density base material. Its advantages and limitations are as follows:
Advantages: Water-resistant TPE, by adding a polyester anti-hydrolysis agent, maintains material stability in humid environments, preventing swelling and deformation. Its smooth, easy-to-clean surface resists water accumulation, making it suitable for humid areas that require frequent cleaning (such as fresh produce washing areas). It also offers better wear resistance than EPDM, and wears more slowly on surfaces with a small amount of gravel.
Limitations: Its anti-slip performance is slightly inferior to EPDM, with a coefficient of friction on wet surfaces of approximately 0.5-0.55. This requires optimizing the wheel tread (e.g., adding anti-slip bumps). Furthermore, prolonged immersion in standing water (such as in aquaculture areas) can shorten its service life to 5-6 months. Avoid prolonged contact with standing water.

3. Materials to Avoid
Natural rubber (NR) and nitrile rubber (NBR) casters should be strictly avoided in humid environments. Natural rubber has poor water resistance, and the wheel tread will become sticky and crack after 1-2 months in humid environments. While nitrile rubber is oil-resistant, it is prone to debonding at the axle-tread joint when exposed to water. Its poor anti-slip properties also make it prone to slipping on wet surfaces, posing a safety hazard.
In summary, ethylene propylene diene monomer (EPDM) casters are preferred in humid supermarket environments. If both wear resistance and performance are required, water-resistant TPE casters can be used. Both types of casters should be paired with rust-resistant axles to maximize their suitability for humid environments.