A. Soft Polyurethane Foam (commonly known as sponge): Sponges used for sofa filling are mainly divided into three categories: Conventional sponge is a sponge mainly composed of conventional polyether and TDI. Its characteristics include good resilience, softness, and breathability; High-resilience sponge is a sponge mainly composed of active polyphosphate and TDI, characterized by excellent mechanical properties, good elasticity, high compressive load, flame retardancy, and good breathability; Random-pore sponge is a sponge with pores of varying sizes, resembling natural seaweed, characterized by good elasticity and cushioning during compression and rebound.
B. Down Filling: Down as sofa filling provides a comfortable seating experience and minimal deformation over long-term use. Its disadvantages include slow rebound and high cost. It is generally used in conjunction with sponge in high-end sofas or is suitable for use as cushions.
C. Artificial Cotton Filling: Artificial cotton as sofa filling provides a comfortable seating experience, but its mechanical properties are poor, and its compressive load is low, making it only suitable for cushions. The choice of sofa filling material varies greatly depending on the type of filling material. Generally, the filling material for fabric sofa cushions should ideally be high-resilience foam with a density of 30 kg/m³ or higher. Most sofas use a single piece of foam for filling, but the best approach is to combine high-resilience foam with irregularly sized foam, along with down or synthetic cotton, to increase comfort and lifespan. When choosing a sofa, inquire about the type of filling. If it's foam, check its density, feel the cushion's rebound under pressure, and assess its comfort while sitting on it.
For foam cushions, the national standard is 25 kg/m³, and the international standard is 35 kg/m³. For the bottom structure, a high-elasticity serpentine spring structure is superior to a webbing structure, and high-quality webbing is better than low-quality webbing. After prolonged compression, a high-quality webbing structure should quickly rebound, returning to its original shape without deformation or sagging.
