Expandable graphite, as a flame retardant material, has the following characteristics compared with traditional flame retardant materials: less smoke production during fire protection; no decline, no secondary fire; and instantaneous expansion force, good flame retardant effect Therefore, it is especially favored by users at home and abroad.
Expandable graphite is mainly used in the following areas in the field of flame retardant and fire protection:
Fire seal
Due to the expandability, high temperature resistance and thermal insulation of expandable graphite, it has become an excellent sealing material and is widely used. At present, there are mainly two forms: the first is to mix and shape expandable graphite with rubber materials, inorganic flame retardants (aluminum hydroxide), accelerators, vulcanizing agents, and reinforcing agents to form various specifications. Expansion seal. Mainly used in fire doors, fire windows, etc. This kind of sealing strip has the function of blocking the flow of smoke in the fire. The other is to use glass fiber as a carrier to use a certain kind of adhesive to adhere the expandable graphite to the carrier. It is mainly used in the manufacture of fire doors.
2.Fire bag, fire blocking material, fire ring
Because expandable graphite has a high expansion rate under high temperature conditions, it can be made into fireproof bags and fire blocking materials. As an effective expansion and flame retardant material, it is used for fire blocking in buildings. Such as sealing building pipelines, to prevent the spread of fire in the event of a cable or gas pipeline fire.
3.Fire board
Because the expandable graphite has a small density and stable crystals, it is often used in the mixture of fire-resistant boards. The purpose is to increase the fire-resistant performance of the boards, reduce the density of the boards, and enhance the thermal insulation performance. Expanded graphite is often developed into thin sheets. This material can be used to make flame retardant panels for walls and other combustible substrates. In this application, small-scale natural flake graphite particles can be directly pressed into boards as the initial raw material. Fires When this happens, the fine particles of graphite can expand to form a denser fire barrier.
4. Flame retardant coating
In recent years, expandable graphite is being tried in flame retardant coatings, which can give coatings excellent thermal expansion properties. The United States has recently proposed a flame retardant coating composed of fiber reinforced materials, expandable graphite, solid heat-absorbing materials, polymer binders, etc., which can be used for gutter coating of fiberboard and wood boards. The coating overcomes the shortcomings of the previous coatings which are prone to smoke. In a fire, it can quickly expand to form a light carbon layer, and less toxic gases (such as SO2, NO, etc.) are emitted. Can effectively protect the substrate from fire. But the black surface of graphite has limited its popularization. Surface modification to change its color and increase the color variety of coatings to make their colors acceptable to the public is the focus of this research.
5. Flame retardant plastic
The expanded carbonized layer formed by expandable graphite carbon has excellent heat insulation performance and high temperature resistance. Expandable graphite is the only expansion agent found to date that can be used under severe conditions and has sufficient expansion strength. The application of expandable graphite in flame retardant plastics mainly uses the expandability and thermal insulation of expandable graphite. For example, the expansion effect of graphite sheets dispersed in polyurethane foam can prevent combustion and reduce fire, and it also acts as heat insulation.
At present, a large number of expandable graphites have been reported for flame retardant polyurethane, flame retardant polyolefin, flame retardant rubber, flame retardant polystyrene plastic, flame retardant carbonate oligomer, flame retardant asphalt and flame retardant cable.