Methods for making flame-retardant rubber products With the exception of a few synthetic rubbers, most synthetic rubber products, like natural rubber, are flammable or combustible materials. At present, the method of adding a flame retardant or a flame retardant filler and the blending modification with a flame retardant material are mainly used to improve.
Method for manufacturing flame retardant rubber products
With the exception of a few synthetic rubbers, most synthetic rubber products, like natural rubber, are flammable or combustible materials. At present, the method of adding a flame retardant or a flame retardant filler and blending with a flame retardant material to improve flame retardancy are mainly used. In addition, the introduction of a flame retardant group in the monomer during polymerization is also an effective method in the flame retardant technology, and improving the crosslink density of the rubber product also has a good influence on the flame retardancy. The flame retardant technology of rubber is briefly described below.
1. Hydrocarbon rubber
Hydrocarbon rubbers include NR, SBR, BR, IIR, EPR, EPDM, and the like. Although NBR is not a hydrocarbon rubber, its flame retardant technology is very similar to that of hydrocarbon rubber, so it is treated by human hydrocarbon rubber.
The hydrocarbon rubber has an oxygen index of about 19 to 21 and a thermal decomposition temperature of 200 to 500 ° C. The heat resistance and flame retardancy are generally poor, and most of the decomposition products during combustion are flammable gases. The techniques commonly used for flame retardancy of such rubbers are as follows.
Blending with the flame retardant polymer, such as polyvinyl chloride, vaporized polyethylene, chlorosulfonated polyethylene, ethylene-vinyl acetate and other high polymer blends, can appropriately improve the flame retardancy of the hydrocarbon rubber. Care should be taken to consider compatibility and co-crosslinking issues during blending.
Adding flame retardant This is an important way to improve the flame retardancy of hydrocarbon rubber, and the synergistic effect of the flame retardant is used to further improve the flame retardant effect. Most commonly used flame retardants are organic halogen flame retardants, among which perchlorocyclopentanone, decabromodiphenyl ether, chlorinated paraffin, etc. are used more. The inorganic flame retardant used in combination is mostly ruthenium trioxide, followed by zinc borate, hydrated alumina, and vaporized ammonium. Note that the halogen-containing flame retardant should not contain free halogen during use, because free halogen will corrode equipment and mold during processing, which has an adverse effect on the electrical properties and aging properties of the rubber. In addition, attention should be paid to the adverse effects of the amount of flame retardant on the mechanical properties of the rubber.
A flame retardant inorganic filler such as calcium carbonate, clay, talc, silica, aluminum hydroxide or the like is added to minimize the proportion of combustible organic substances. Calcium carbonate and aluminum oxynitride have an endothermic effect when decomposed. This method will reduce some of the physical and mechanical properties of the compound, and the filling amount should not be too large.
The crosslink density test of the rubber has proved that increasing the crosslink density of the rubber can increase its oxygen index. Therefore, the flame retardancy of the rubber can be improved. This may be due to an increase in the thermal decomposition temperature of the compound. This method has been applied in ethylene propylene rubber.
The halogen-containing rubber contains halogen elements, the oxygen index is generally between 28 and 45, and the oxygen index of FPM is even above 65. Generally, the higher the halogen content in the halogen-containing rubber, the higher the oxygen index. This type of rubber itself has a high flame retardancy and self-extinguishing from the fire. Therefore, its flame retardant treatment is easier than hydrocarbon rubber. In order to further improve the flame retardancy of the halogen-containing rubber, a method of adding a flame retardant can be usually employed.
3.Miscellaneous chain rubber
The most representative of these rubbers is dimethyl silicone rubber, which has an oxygen index of about 25 and a thermal decomposition temperature of 400 to 6001:. The practical flame retardant route is to increase the thermal decomposition temperature, increase the residue during thermal decomposition, and slow down the generation rate of flammable gas.