Main types of raw materials:
1. Hydrocarbons
n-pentane, isopentane, cyclopentane: These are among the most commonly used blowing agents in expanded polystyrene (EPS) and rigid polyurethane (PU) foams. Advantages include low cost and good foaming performance; the disadvantage is flammability.
2. Halogenated hydrocarbons (containing chlorine/fluorine)
Hydrochlorofluorocarbons (HCFCs): For example, HCFC-141b. Due to their ozone-depleting potential, they are being phased out.
Hydrofluorocarbons (HFCs): For example, HFC-134a, HFC-245fa. They have zero ozone depletion potential, but high global warming potential, and their use is also being restricted.
Hydrofluoroolefins (HFOs): For example, HFO-1234ze, HFO-1336mzz. These are a new generation of environmentally friendly blowing agents with zero ozone depletion potential and extremely low global warming potential, and are currently a key area of development.
3. Inert gases
Carbon dioxide (CO₂): Widely used in flexible polyurethane foams, usually generated by the reaction of water with isocyanate, or by directly injecting liquid CO₂. Environmentally friendly, non-toxic, and low cost.
Nitrogen (N₂): Commonly used in the compression molding foaming of materials such as rubber and EVA, environmentally friendly and safe.
4. Others
Water: In polyurethane foams, water is a crucial chemical blowing agent (generating CO₂ through reaction with isocyanate), but from a physical perspective, it is also a source of gas production.
