A large number of wooden furniture, plastic decorative materials, textiles, etc. in the room are also flammable objects. Without the protection of flame retardants, fire hazards are everywhere. But for most people, "what the hell is a flame retardant" doesn't really matter to them. Because people can't see it at all and have no way of knowing its existence. However, in modern life, flame retardants are almost everywhere. In the cell phones we carry around, the computers on our desks, the subways we take every day, the cars we drive, and even the mattresses that make you sleep soundly every night, thousands of flame retardant molecules are like The vigilant little guards are always ready, silently guarding your life and property safety, keeping us away from the threat of fire.
one. What are flame retardants:
"Flame retardant", as the name implies, is a preparation that can effectively prevent fire, making flammable materials become inflammable or even non-flammable after being treated or added. It is a functional additive that imparts flame retardancy to flammable polymers. The flame retardant design of molecular materials; there are many types of flame retardants, which are divided into additive flame retardants and reactive flame retardants according to the method of use.
two. The main flame retardant principles of flame retardants are:
1. Add flame retardant during the compounding process. That is, by mechanical mixing, the flame retardant is added to the polyamide to obtain flame retardancy. If a certain proportion of APP/talc is added to PA6, PA6 with UL94V-0 flame retardant grade can be obtained. The advantage is that it is easy to use and has a wide range of applications, but it has a great influence on the physical and mechanical properties of the polymer. The main additive flame retardants that can be used for polyamides are decabromodiphenyl ether, ammonium polyphosphate, aluminum alkyl phosphinate, etc. The use of additive flame retardants is currently the main method of nylon flame retardant.
2. Grafting or bonding flame retardant groups on the polymer chain or on the surface. That is, the flame retardant is used as a reactive monomer to participate in the reaction, and is combined with the main chain or side chain of the polyamide, so that the polyamide itself contains flame retardant components. It is characterized by good stability, low toxicity, little impact on the performance of the material, and durable flame retardancy, which is an ideal method. However, the operation and processing technology are complicated and the cost is high, which is not as common as the additive flame retardant method in practical application. Reactive flame retardants for polyamides are bis(hydroxyethyl)methylphosphine oxide, 1,3,6-tris(4,6-diamino-2-thiotriazine)hexane and melamine Mixtures of acids, etc.;
3. Copolymerization with flame retardant monomers (such as caprolactam, diamine or dibasic acid, etc.). This method has high requirements for flame retardants, more complicated operation and processing technology, and is rare in practical applications.
three. Inorganic flame retardants mainly add inorganic elements with intrinsic flame retardancy to the flame-retardant substrate in the form of simple substances or compounds, fully mix them with high polymers in a physically dispersed state, and pass chemical or Physical changes act as flame retardants.
1. Antimony trioxide: It is an additive flame retardant, often used in combination with other flame retardants and smoke suppressants, and each component can produce a synergistic effect. In the early stage of combustion, antimony trioxide first melts, forms a protective film on the surface of the material to isolate the air, and reduces the combustion temperature through an internal endothermic reaction. Antimony trioxide is vaporized at high temperature, which dilutes the oxygen concentration in the air, thereby playing a flame retardant effect.
2. Aluminum hydroxide (ATH): Aluminum hydroxide is the most popular flame retardant for inorganic hydroxides. Aluminum hydroxide flame retardant plastics are less smoky in flames, which is a distinct advantage.
3. Magnesium Hydroxide (MDH): Magnesium hydroxide is an inorganic flame retardant with better thermal stability. It is still stable when it exceeds 300 °C. It is widely used in many artificial rubbers, resins, including engineering plastics and others under high temperature processing. of resin. In the polymer system, it plays the role of flame retardant and smoke elimination. When used in combination with ATH, it complements each other, and its flame retardant effect is better than that used alone.
The above is some explanations about the flame retardant principle of flame retardants compiled by Xiaobian, hoping to help everyone.
