Welcome to visit the official website of Dongguan Hongcheng New Material Co., Ltd!

Your current location : Home >> News >> Technical knowledge

KeywordsKeywords

Contact UsContact Us

Ningbo Hongyi Chemical Co., Ltd

Tel:86-769-2277 5680   /22775660/2218 4903

Fax:86-769-22781165

Mob:18929238988/13790281535

Address:Industrial Zone, guanqiaoyong village, Wangniudun Town, Dongguan City, Guangdong Province

Web:www.hongchengpu.com

Web:en.hongchengpu.com

Mechanism of typical flame retardant (liquefied MDI)

2020-07-24 21:00:31
second

▼▼▼


Mechanism of typical flame retardants


The combustion of polymer is a very intense complex thermal oxidation reaction with the characteristics of emitting thick smoke blazing flame. The general process of combustion is that under the constant heating of external heat source, the polymer first reacts with oxygen in the air to produce volatile combustible materials. When the substance reaches a certain concentration temperature, it will ignite burn. Part of the heat released by combustion supplies the polymer being degraded, which further intensifies its degradation produces more combustible gases flames In a very short time, it will spread rapidly cause a fire.


典型阻燃剂(液化MDI)机理大全

Flame retardant is a kind of additive which can prevent plastic igniting flame spreading. According to the use method, it can be divided into two types: additive type reactive type. According to the chemical structure, flame retardants can be divided into inorganic organic. The flame retardant mechanism of all kinds of flame retardants is necessary necessary for today's flame retardant engineers. Today, we will summarize the flame retardant mechanism of several typical flame retardants.

典型阻燃剂(液化MDI)机理大全



Flame retardant mechanism of several typical flame retardants






Mechanism of halogen flame retardant

Halogenated flame retardants include bromine chlorine flame retardants. Halogenated flame retardant is one of the largest organic flame retardants in the world. Most of halogenated flame retardants are brominated flame retardants. The brominated flame retardants produced in industry can be divided into additive type, reactive type polymer type, there are many kinds of them. There are more than 20 kinds of additive brominated flame retardants, more than 10 kinds of polymer brominated flame retardants, more than 20 kinds of reactive brominated flame retardants in the domestic foreign markets. Additive flame retardants mainly include decabromodiphenyl ether (DBDPO), tetrabromobisphenol A, bis (2,3-dialkylpropyl) ether (TBAB), octabromodiphenyl ether (obdpo), etc.; reactive flame retardants mainly include tetrabromobisphenol A (TBBPA), 2,4,6-tribromophenol, etc.; polymer flame retardants mainly include brominated polystyrene, brominated epoxy, tetrabromobisphenol A carbonate oligomer, etc.

典型阻燃剂(液化MDI)机理大全






磷及磷化合物的阻燃机理

磷及磷化合物很早就被用作阻燃剂使用,对它的阻燃机理研究得也较早,从磷化合物在不同反应区内所起阻燃作用可分为凝聚相中阻燃机理和蒸汽相中阻燃机理,有机磷系阻燃剂在凝聚相中发挥阻燃作用。其阻燃机理如下:

在燃烧时,磷化合物分解生成磷酸的非燃性液态膜,其沸点可达300℃。同时,磷酸又进一步脱水生成偏磷酸,偏磷酸进一步聚合生成聚偏磷酸。在这个过程中,不仅由磷酸生成的覆盖层起到覆盖效应,而且由于生成的聚偏磷酸是强酸,是很强的脱水剂,使聚合物脱水而炭化,改变了聚合物燃烧过程的模式并在其表面形成碳膜以隔绝空气,从而发挥更强的阻燃效果。

磷系阻燃剂的阻燃作用主要体现在火灾初期的高聚物分解阶段,因其能促进聚合物脱水发化,从而减少聚合物因热分解而产生的可燃性气体的数量,并且所生成的碳膜还能隔绝外界空气和热。通常,磷系阻燃剂对含氧聚合物的作用效果好,主要被用在含羟基的纤维素、聚氨酯、聚酯等聚合物中。对于不含氧的烃类聚合物,磷系阻燃剂的作用效果就比较小。

含磷阻燃剂也是一种自由基捕获剂,利用质谱技术发现,任何含磷化合物在聚合物燃烧时都有PO·形成。它可以与火焰区域中的氢原子结合,起到抑制火焰的作用。另外,磷系阻燃剂在阻燃过程中产生的水分,一方面可以降低凝聚相的温度,另一方面可以稀释气相中可燃物的浓度,从而更好地起到阻燃作用。
典型阻燃剂(液化MDI)机理大全






Flame retardant mechanism of inorganic flame retardant

Inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, expanded graphite, borate, aluminum oxalate zinc sulfide based flame retardants. Aluminum hydroxide magnesium hydroxide are the main varieties of inorganic flame retardants. They have the characteristics of non-toxic low smoke. Due to the absorption of a large amount of heat in the combustion zone by thermal decomposition, the temperature of the combustion zone is reduced below the critical temperature of combustion, the combustion is self extinguishing. Most of the metal oxides generated after decomposition have high melting point good thermal stability, which cover the surface of combustion solid phase to block heat conduction radiation, thus playing a flame retardant role. At the same time, a large amount of water vapor is produced by decomposition, which can dilute combustible gas also play a flame retardant role.

典型阻燃剂(液化MDI)机理大全

The synergistic effect of halogen-containing flame retardants phosphorus containing flame retardants is remarkable. For the synergistic effect of halogen phosphorus flame retardancy, it is proposed that halogen phosphorus compounds can promote the decomposition of each other, form halogen phosphorus compounds their conversion pbr3, PBR ·, pobr3, etc. The synergistic effect of halogen phosphorus was studied by pyrolysis gas chromatography, differential thermal analysis, differential scanning calorimetry, oxygen index determination temperature programmed observation of flame retardants. The results showed that the decomposition temperature of flame retardants was slightly lower than that of single halogen phosphorus flame retardants, the decomposition was often severe. The smoke cloud formed by chlorine phosphorus compounds their hydrolysates in the combustion zone could last a long time It remains in the combustion zone forms a strong gas phase isolation layer.


典型阻燃剂(液化MDI)机理大全


Label

Next article:None

Service hotline:

86-574-8631 5539