What Are The Applications Of Polyurethane Foam In The Transportation Industry? – Part 1

In the transportation industry, polyurethane foam is mainly used as cushioning, interior materials, and energy-absorbing shockproof materials. Whether in airplanes, trains, automobiles, ships, boats, or lifeboats, soft, integral skin, rigid, semi-rigid polyurethane foams, and products like RIM, RRIM, and SRIM are essential.

Automobile manufacturing

Due to the increasing focus on energy conservation, the use of polyurethane foam in the automotive industry has significantly grown. In 1969, a mid-sized American car used 7.9 kg of polyurethane foam; by 1979, this had increased to 20 kg. In China, an Iveco van requires 40 kg of polyurethane foam per vehicle. The application of polyurethane foam significantly reduces vehicle weight and fuel consumption. Its low cost allows for versatile design options. Additional benefits include soft interior touch, driving comfort, noise reduction, thermal insulation in summer, and heat retention in winter. As the automobile industry continues to expand, so does the market for polyurethane foam.

Soft foam cushions, backrests, headrests, etc.

Nearly all cars—including sedans, buses, and trucks—use soft polyurethane foam for seats and backrests. It is economical, durable, comfortable, and safe.

Manufacturing of soft foam cushions typically uses hot molding and cold molding processes. Seat cushions are the largest component of polyurethane foam in vehicles and are the most comfort-sensitive. Cold-molded cushions made from high-activity polyether and polymer polyols offer high resilience and excellent load-bearing performance (indentation factor ≥ 3 seconds), providing better comfort than hot-molded cushions. However, due to the low cost and availability of raw materials, hot molding still has a market. Flame-retardant cushions are necessary for safety. Driver seats require higher performance standards than passenger seats.

Seats must always provide sufficient space for passenger movement, and the effects of acceleration in both horizontal and vertical directions must be balanced. Seat design should align with human anatomy, and seat pressure distribution should be optimized for comfort.

Through surface design of the foam, pressure distribution can be improved. Although hardness is uniform across the material, IFD performance can be adjusted based on area, thickness, and shape. This design also enhances moisture wicking and heat transfer under the seat cover. Using full-foam cushions with two different hardness levels increases comfort: softer foam at contact areas improves sitting feel, while harder foam at the base and sides provides support during vehicle operation, especially while turning. For enhanced performance, semi-rigid foam inserts can be directly foamed in place or bonded to hard support plates using foam adhesives.

Dual-hardness foam one-step molding is a relatively easy technique, where two foams of different densities are cast in one shot to form a composite part.

The headrest is also a critical component in cars. Modern designs, such as headrests with tubular metal inserts wrapped in approximately 20 mm thick integral skin foam, must meet specific requirements.