The flame-retardant finishing of the wool fibers is initially using inorganic boric acid, phosphoric acid, and salts thereof. The durability of this finish method for non-finishing, not washable, only the curtain for theater; later modified 4-hydroxymethyl Chloride (THPC) and its derivatives, sulfamate wool resistance burning finishing up a semi-permanent level; since developed to take advantage of titanium, zirconium fluoride complex, carboxylic acid complex processing wool, this method can reach a permanent level; later developed in order to meet the higher requirements, wool high temperature firefighting clothing fiber blend fabric.
Blended with flame retardant fiber
Wool is a natural flame retardant fiber blended with other fibers can be made of high temperature resistant fabric, good flame retardant properties, and the price is cheap, simple processing, is widely used in protective clothing, bedding, upholstery, carpets and other aspects. Aramid 1313, Kevlar and wool blended more than 30%, limiting oxygen index can reach more than 28 high temperature resistant fibers on the market, has good flame resistance. High temperature phenolic fibers and wool blend its content is up to 35%, and the fabric has a flame retardant. Recently, the European market retardant viscose fiber, the study found it very easy and wool fiber blend. Such fibers contain a high proportion of silica and metal fumes small, non-toxic, wool therewith blend can improve the thermal decomposition temperature, to achieve the purpose of flame retardancy. At present, this method has been widely used, blended Visil content is about 60%.
Metal complex processing
It is currently wool flame retardant finishing the most widely used and the most mature technology, mainly titanium or zirconium fluoride complex, typically titanium (zirconium) / fluorine molar ratio of 1:6, such as K2TiF6 or K2ZrF6 in acidic conditions under (generally the pH about 2.5), a temperature of 70 ° C, processing for 30 minutes, which is the the famous "Zirpro" process. The before and after dyeing or staining process can be carried out. Flame retardant mechanism for the wool under acidic conditions, the amino group to amino positive ions, the reaction occurs with a flame retardant anionic adsorption combustion to increase the formation of carbon, reducing the generation of the combustible gas, so as to achieve fire fighter apparel purposes.
The reaction is as follows (zirconium salts, for example):
W-NH2 (wool fiber) + H + → W-NH +3, W-NH +3 + ZRF2-6 → W-NH +3 · ZRF2-6.
Furthermore, after washing, ZrF2-6 hydrolyzed into ZrOF2, fluorozirconate in the combustion of the heated, fluoride is also gradual decomposition temperature of 300 ° C or more generated ZrOF2 very fine particles ZrOF2, itself does not burn, and wool fibers mixing or covering the surface of the fiber, fire prevent a large number of combustible pyrolysis gas escape, and thus play a flame retardant.
Tetrabromophthalic anhydride (TBPA) is added to the finishing, from about 10% to 15% (weight) on the fabric; The additives may react with wool fibers, to further improve the flame retardancy. Proven titanium, zirconium fluoride complex is finished, the flame-retardant effect can withstand 50 times the hard water washing and dry cleaning, as durable flame retardant finishing. The study also found that, after finishing titanium complex fabric than fabric flame retardant finishing by zirconium complexation effect, but serious cause fabric yellowing, commonly used zirconium salts finishing. The flame-retardant effect of the technology for all to see, the flame retardant finishing wastewater contains large amounts of heavy metal ions, titanium, zirconium, causing environmental pollution. In the near future, this technology is bound to be environmentally friendly flame retardant finishing technology instead.