Development And Performance Research Of High-performance And Low-cost Thermal Protection Materials For Firefighting Clothin

The firefighting clothing is an important barrier for firefighters to resist the hazardous fire environment.The clothing is comprised of 4 layers including outer shell,moisture barrier,thermal barrier and comfortable inner.At present,high performance fibers such as aramid fiber,PBI and so on are often used as the outer layer of firefighting clothing;High performance fibers such as polysulfone fiber and polyimide（PI）are often used as the thermal insulation layer,and they have been widely used in the market.The use of aramid fiber accounts for the main part,but there are still many problems with aramid fiber.First of all,the development of domestic aramid industry is late,resulting in backward production technology.Domestic aramid 1414 has made breakthrough progress in recent years,but its performance is still not as good as foreign.About 80%of aramid 1414 of China market is occupied by foreign brands.In addition,the shortage of aramid raw materials leads to expensive prices,which makes many industries that should use flame retardant and heat-resistant textiles not fully applied.Based on this,in this study,different functional fillers were mixed in silicone resin solution and coated on glass fiber fabric to prepare outer barrier of firefighting clothing;In addition,this paper attempted to use fiber with low cost and excellent flame retardant property to prepare thermal insulation layer,in order to prepare a new type of thermal insulation layer with good thermal protection performance,which greatly reduced the cost of the overall firefighting clothing.Firstly,based on the energy band theory,electronic transition theory and refractive index of pigments,the functional pigments with near infrared reflection and functional fillers with good flame retardant property were selected.Fe₂O₃,silica nanoparticles and mica powder were selected as functional pigments and fillers.The optimal filler formula was selected by orthogonal experiment and placed in solvent-based silicone resin to prepare coating solution,which was coated on low-cost glass fiber fabric to prepare high-performance and low-cost outer barrier of firefighting clothing.In order to improve the air permeability and environmental protection of coated fabric,flame retardant pigments and fillers were added to waterborne silicone resin to spray glass fiber fabric to prepare coated fabric,and the properties were characterized.For the thermal insulation layer of firefighting clothing,the influence of the composition,proportion and the reinforcement method of insulation felt on the thermal performance of insulation felt were studied in this paper.Finally,preoxidized fiber,PPS fiber and flame retardant acrylic fiber with excellent performance and low cost were selected to prepare thermal insulation felt by spunlaced process.A series of studies were carried out on its performance,and the main conclusions are as follows:（1）Preparation and properties of solvent silicone coated glass fiber fabric.The thickening effect of silica nanoparticles was better than that of aerogel and hollow glass microspheres.When the concentration of silica nanoparticles was 6%,the coating solution had good coating performance.Moreover,silica nanoparticles had better thermal insulation performance than aerogel and hollow glass microspheres.In the orthogonal experiment,the coating formula with good thermal protection performance was silica nanoparticles 6%,mica powder 6%,and Fe₂O₃5%,and the TPP value of this fabric was 413 k W·s/m².The flame retardancy and thermal stability met the GA10-2014 industry standard.Moreover,the water repellency of the fabric was good,and the contact angle was 107.95°.（2）Preparation and properties of air-permeable and environmentally friendly waterborne silicone coated glassfiber fabric.The coated fabric with three layers sprayed at 25 cm from the bandage needle plate was selected as the good coated fabric,and its TPP value was 315.10 k W·s/m²,which was better than 311.92 k W·s/m²of commercial aramid fabric.The coated fabric had good air permeability,and its air permeability was 13.30 mm/s.The longitudinal breaking strength of the fabric was1182.86 N.The contact angle of the sprayed fabric was measured to be 102.9°by the contact angle measuring instrument.（3）Preparation and performance study of spunlaced thermal insulation felt for firefighting clothing.Six kinds of multi-component insulation felt composed of pre-oxidized fiber,PPS fiber and flame retardant acrylic fiber had good flame retardant property.When the ratio was 35:60:5,the longitudinal char length of the thermal insulation felt was 23 mm,which was less than 72 mm of the commercial aramid felt.The thermal conductivity of the insulation felt was 0.0515 W/m·K,meanwhile the commercial aramid insulation felt was 0.0504 W/m·K,both of them had good insulation performance.The self-made insulation felt also had good air permeability and thermal stability.The properities of the insulation felt could meet the standard of firefighting clothing.Therefore it was suitable to be used as the thermal insulation layer of firefighting clothing.（4）The thermal protection performance of the firefighting clothing composed of self-made solvent-based scraping coated fabric and self-made thermal insulation layer with commercial moisture barrier and comfortable inner had the same TPP value as the commercial firefighting clothing,which reached to 1264.40 k W·s/m²（30.22cal/cm²）.Moreover,the TPP value of the firefighting clothing composed of self-made spraying flame retardant layer and self-made insulation layer combined with commercial moisture barrier and comfortable layer reached 1209.59 k W·s/m²（28.91cal/cm²）,which met the standard of firefighting clothing（28.00 cal/cm²）.