Introduction to the flame retardant properties of polyurethane foam

Polyurethane foam contains flammable hydrocarbon segments , small density, large specific surface area, polyurethane without flame retardant treatment is combustible and will burn in case of fire. Once it catches fire, the burning process will be very fast. Combustion and decomposition will produce a large amount of toxic smoke, making it difficult to extinguish the fire. In particular, polyurethane soft foam has a high porosity and many combustible components. When burning, it continuously supplies oxygen due to its high air circulation, making it flammable and difficult to self-extinguish. Many application fields of polyurethane foam, such as building materials, mattresses, furniture, insulation materials, car seat cushions and interior materials, have flame retardant requirements. Foreign countries attach great importance to the flame retardancy of polyurethane foam materials and have promulgated many flame retardant regulations and standards. Our country has successively put forward flame retardant requirements for polyurethane foam used in aircraft, ships, railway vehicles, automobiles, other important industry components, equipment and certain places, and many have adopted flame retardant grade polyurethane foam.

The so-called flame retardant actually refers to a specific standard that meets a certain specification or a certain test method. The “flame retardant” or “flame retardant” of polyurethane rigid foam is generally just for For a small fire, it can still burn in a big fire. However, foam plastics with good flame retardant properties are less likely to cause fires. Even if a fire occurs, the reduction in combustion performance can reduce the risk of rapid fire spread and the production of irritating and toxic smoke.

Generally, flame retardants are added to improve the flame retardancy of foam plastics to delay combustion, prevent smoke and even make the fire site self-extinguishing. Polyols (and reactive flame retardants) containing flame retardant elements can also be used as foam raw materials.

In addition to adding flame retardants to the foam, there are several other methods to obtain flame-retardant foam. The most important one is to manufacture polyisocyanurate rigid foam through the trimerization reaction of isocyanate. This type of foam has Good flame retardancy and heat resistance.

Foam plastics with higher flame retardancy can be produced by combining the addition of flame retardants and trimerization catalysts.

For ordinary foam plastics, the impregnation method can also be used to make it flame retardant. This method generally uses a flame retardant solution or dispersion containing adhesive to impregnate polyurethane soft foam. After rolling to remove excess solution, the flame retardant soft foam can be obtained by drying. Because the impregnation treatment is carried out after foam molding, the impregnation is not limited by the foaming process, and the amount of flame retardant can be appropriately increased. Sometimes the flame retardant effect is more obvious than the additive method, and the oxygen index of the product is as high as29.5~34.3, the amount of smoke produced during combustion is small. The key to the impregnation flame retardant treatment of PU soft foam is to develop a flame retardant liquid formula that has sufficient adhesion to the PU soft foam meridian after drying but does not harden the foam.