Retardant outer

( 1 ) an aromatic polyamide fibers. Aromatic polyamide fibers into isophthaloyl phenylenediamine fiber ( foreign trade name Nomex, domestic trade name Kevlar 1313 ) and Terephthaloyl phenylenediamine fiber ( foreign trade name Kevler, domestic trade name Kevlar 1414 ) . Nomex is currently the world's most popular use of protective clothing materials , the protective clothing can effectively provide protection sudden fire caused by hazards, including heat and flame , it is because a flame and high temperature resistant Nomex fiber , the case fire does not melt drip, does not support combustion ; another Nomex protective clothing provided protection is permanent, will not wash or wear is reduced .

1313 aramid fibers are connected to each other by the amide bridges consisting of aryl, linear macromolecules . Since strong hydrogen bonds , so that structural stability , with excellent heat resistance and excellent flame retardant properties, chemical resistance and mechanical properties , etc. [ 5 ] aramid fiber 1313 in the general state can maintain a higher temperature strong , at 177 ~ 200 ℃ operating temperature , time of up to 20 000 h still maintain the original strength of about 90%. In flames flammable , LOI ( LOI ) value reached 29 to 32. Resistant to most acids , alkalis , bleaches and solvents , breaking strength 0.47 N / tex (1 tex = 10-6kg / m). In short, better overall performance aramid fiber 1313 , heat durability, wear resistance, and good times inflection , and resistance to various chemical reagents, thus suitable for making explosive environments overalls and materials used at high temperatures [ 5 ] .

(2) Visil fibers. Visil fibers are manufactured in Finland Sateri OY a new high-temperature flame-retardant viscose fiber , the fiber composed of cellulose and silicate composition, not a mere cellulose fibers. It is in the viscose fiber production process , based on a two-phase natural regeneration process produced a hybrid fibers. The cellulose-based fiber , which is formed inside the macromolecular network and the number of silicate molecules chemically bound water . Silicates combined with water to make changes in the combustion performance of cellulose , in particular aluminum silicate surface characteristics change . The pyrolysis process, the surface of the part to help bind the inorganic atoms , thus retarded combustion . It is this cause and effect of chemical release of water , making the burning speed is slow, if you remove the source of fire , with a self-extinguishing capability. Visil chemical release of water is a flame retardant fiber is an important factor .

Visil fibers and general physical and mechanical properties similar to viscose fiber , moisture permeability is not only easy to dye and acid and alkali resistant insects ; compared with other flame retardant fiber , low cost , no pollution , can be processed into a variety of textiles. Such fibers can be inherently biodegradable mixture of organic and inorganic soil . If the carbonization at high temperature , it will produce toxic combustion SiO2. Because of this fiber molecular structure determines the particularity of its technical performance , according to ISO 4589 " Plastics - Determination of burning oxygen index --- sex" standard test, the LOI of 28 to 31 ; regain 9% to 11% ; absorption capacity of 50% to 60% ; single fiber strength of 1.5 ~ 1.9 cN / dtex; elongation rate of 18 % ~ 25% ; silicate (SiO2 + Al2O3) 30% ~ 33%.

( 3 ) polysulfonamide fibers (PSA) [9]. Polysulfonamide that polysulfone amide fibers, is Shanghai Textile Research Institute and the Shanghai Institute of synthetic joint research and production of a high temperature resistant fibers from terephthaloyl chloride and 4,4 ' diaminodiphenyl sulfone and 3'3 diaminodiphenylsulfone as the main raw material after polymerization , dissolved in dimethyl acetamide , and then by wet spinning process or dry spinning process from processing. The fiber-forming polymer which is an amide group and a sulfone group are connected between the bit phenyl and phenyl -bit linear macromolecules composed , on the macromolecular main chain sulfone presence of strong electron-withdrawing group, by conjugated double bonds of benzene ring , it has excellent heat resistance .

Polysulfonamide mechanical properties of aramid 1313 are similar, but its heat resistance, thermal stability, flame resistance superior to Kevlar fiber 1313 . In addition, it has a lubricity, abrasion resistance , impact resistance , electrical insulation and so on. The LOI value of up to 33 , good chemical resistance , in hot air (300 ℃, 2 h) Shrinkage <2 % and the strength retention rate (300 ℃, 100 h) was 80%.

(2) has a good waterproof breathable performance waterproof layer

Waterproof layer close to the outer fabric , play a waterproof , prevent penetration of steam and the role of harmful chemicals . We know that a lot of the general farm use of water when the fire extinguishing agent to put out the fire , if fire service is not waterproof , you have a lot of adverse effects : ① in the winter , fire firefighters wearing wet clothing can cause frostbite ; ② drenched fire close to the flame generated when serving hot steam will cause burns firefighters ; ③ absorbing too much weight will increase , affecting flexibility and comfort . So the main waterproof layer is designed to enable firefighters to keep dry , protect the wearer from toxic fumes and harmful chemicals damage. Meanwhile , firefighters in fire fighting activity volume , sweating more, so fire service to meet the water requirements must also have moisture vapor permeability , so that sweat can be discharged . Therefore, it is necessary to waterproof fabric waterproof layer and also vapor permeability , that is impermeable to water , but water vapor permeable waterproof and breathable fabrics.

The most famous waterproof breathable microporous membrane coated fabrics produced in the United States GoRE GoRE a TEx ⑧ fabric patented by GO both made ??a white GORE TEX membrane , the membrane per square centimeter from the 9 billion hole composition, these holes are 20,000 times smaller than water molecules , 700 times larger than water vapor molecules , while irregular arrangement . Therefore GoRE a TEx ⑧ fabric can make the body's natural sweating exhaust gas , and can block the snow and the cold outside into the human body , which is known as " the body's second skin . GoRE a TEx ⑧ fabrics to the market in 1976 , it is possible to reduce the accumulation of moisture in the fabric , improving comfort , particularly in adverse weather conditions prevent clothing condensation of water vapor generated significant ; Second, in certain conditions , provides the body with an appropriate physiological comfort, maximum waterproof layer minimizes the evaporation of sweat cooling adversely affected.

3 insulation

Statistics show that the temperature of the fire at between 60 ~ 1 100 ℃ , while the radiant heat in the 1.5 ~ 200 kW / (m2 · s), so adapt personal protective clothing must have good thermal protective performance , including anti- direct burning the thermal conductivity and thermal radiation permeability . A thin outer layer of flame retardant alone is not enough , if the increase in the thickness of the outer layer material to meet the requirements , and the cost will be too high . New fire fighting clothing is generally used in taking better performance permanent flame retardant staple fiber nonwoven fabric made ??of thin mat classes , such materials as insulation material fire service fire service thermal protection on particularly prominent role .