It has been more than 30 years since expandable graphite was commercialized. With the development of science and technology, expandable graphite has been widely used, especially in the fields of sealing, flame retardant and anti-electromagnetic interference. Today, I mainly introduce the application of expandable graphite in the field of flame retardant fire prevention, and the development direction of expandable graphite.
As a flame retardant material, expandable graphite has the following characteristics compared with traditional flame retardant materials: less smoke is produced during fire prevention; No depression, no secondary fire; And instant expansion, good flame retardant effect. Therefore, it is especially favored by domestic and foreign users.
Expandable graphite is mainly used in the field of flame retardant fire prevention in the following aspects:
1. Fire seal
Due to the expansibility, high temperature resistance and thermal insulation of expandable graphite, it has been widely used as a good sealing material. At present, there are two main forms: one is to mix expandable graphite and rubber materials, inorganic flame retardant (aluminum hydroxide), accelerant, vulcanizing agent, reinforcing agent and so on to form various specifications of expansion seals. Mainly used for fire doors, fire Windows and other occasions. The sealing strip ACTS as a barrier to the flow of smoke throughout a fire. The other is to use glass fiber as a carrier to use some kind of adhesive to adhesive expandable graphite on the carrier, it is mainly used in the manufacture of fire doors.
2. Fireproof bag, fireproof plugging material and fireproof ring
Because the expandable graphite has a high expansion rate under high temperature conditions, it can be used to make fireproof bags and fireproof plugging materials. As an effective material for expanding flame retardant, it can be used for fireproof plugging in buildings. If the construction pipe is sealed, prevent the fire from spreading when the cable and gas pipe are on fire.
3. The fire prevention board
Due to the low density of expandable graphite and stable crystal, it is often used in the mixture of fireproof sheet materials. The purpose is to increase the fireproof performance of sheet materials, reduce the density of sheet materials and enhance the heat insulation performance. Expanded graphite is often developed and used in thin sheets. This material can be used to make fire retardant panels for walls and other combustible materials. In this use, small size natural flake graphite particles can be directly pressed into boards as initial materials.
4. Flame retardant paint
In recent years, expandable graphite is trying to be used in flame retardant coatings. The United States recently proposed a flame retardant coating consisting of fiber-reinforced materials, expandable graphite, solid heat-absorbing materials, polymer binder, etc., which can be used for furrow coating of fiber board and board. This coating overcomes the shortcoming that the paint is easy to produce smoke in the past. In a fire, it can expand rapidly to form a light carbon layer, and less poisonous gas (such as SO2, NO, etc.) is released. It can effectively protect the base material against fire. But the black surface of graphite limits its widespread use. It is the focus of this research that surface modification is used to change its color, increase the color variety of coating and make its color acceptable to the public.
5. Flame retardant plastics
The expansive carbonization layer formed by expandable graphite carbon has excellent thermal insulation and high temperature resistance. Expandable graphite is the only dilatant found so far that can be used in harsh conditions and has sufficient expansion strength. The expansion and adiabatic properties of expandable graphite are mainly used in flame retardant plastics. For example, the expansion of graphite sheet dispersed in polyurethane foam can prevent combustion, reduce fire, and also play a role of heat insulation.
At present, extensive reports have been made on expandable graphite for flame retardant polyurethane, flame retardant polyolefin, flame retardant rubber, flame retardant polystyrene plastics, flame retardant carbonate oligomers, flame retardant asphalt and flame retardant cables.