Aramid fiber is no stranger to composite materials (here composite materials refer to resin-based fiber composite materials), because it is cost-effective, and it is destined not to be fully covered like glass fiber, nor is it as obvious as carbon fiber. Features and is widely used.
Aramid composite materials are widely used in general military industry, such as fighters, bulletproof armored vehicles, light tanks, bulletproof money transport vehicles, and bulletproof boards. During the Gulf War, aramid composite materials were used extensively on American and French aircraft. At the same time, in order to meet the needs of anti-terrorism, many military and police in developed countries have adopted a large number of para-aramid fibers in their bulletproof vests, bulletproof helmets, stab and cut-resistant clothing, EOD suits, and high-strength parachutes.
Aramid composite materials are also widely used in sports equipment, such as: preparing fishing rods, golf clubs, tennis rackets, bows and arrows, sledges and other products to increase the service life of these equipment.
Aramid fiber can also be used as a coated fabric for air supporting structures and inflatable tape products, such as rubber boats, life rafts, blimps, balloons, and special clothing. It can also be used in shipping, aerospace, rail transit and other fields.
01 Brief introduction of aramid fiber
The full name of aramid fiber is "aromatic polyamide fiber", which refers to the long-chain synthetic polyamide fiber in which more than 85% of the amide bond is directly connected to the benzene ring. The amide bond is connected to the aromatic ring or the derivative of the aromatic ring, which is flame retardant , High temperature resistance, high strength, high modulus, insulation and other outstanding properties. It is a new type of special polymer material. At present, there are two kinds of aramid on the market that have achieved wide commercial application and production, namely meta-aramid and para-aramid.
Meta-aramid has excellent thermal stability, flame retardancy, electrical insulation, chemical stability and radiation resistance. The full name of meta-aramid is "poly-m-phenylene isophthalamide" (MPIA) fiber, which is an organic polymer fiber synthesized from isophthaloyl chloride and m-phenylene diamine. Because the amide bond is connected to the No. 1 and No. 3 positions of the two benzene rings, it is also called Aramid 1313. Meta-aramid has long-term thermal stability, which is its most important feature. It can be used for a long time at a high temperature of 200 ℃ without aging, and has excellent dimensional stability. Meta-aramid is inherently flame-retardant, and its limiting oxygen index (LOI) is> 28%. It will not spontaneously combust or melt in the air, nor will it produce droplets, and will self-extinguish after leaving the flame. The electrical insulation of meta-aramid is excellent, and the insulation paper made of it can withstand breakdown voltage of up to 20kV/mm; meta-aramid has excellent corrosion resistance and radiation resistance. In addition, meta-aramid also has low rigidity, high elongation, and can be processed with conventional textile machinery.
Para-aramid has excellent properties such as high specific strength, high specific modulus, high temperature resistance and flame retardancy, and is known as the world's three major high-performance fibers together with carbon fiber and high-strength high-modulus polyethylene. The full name of para-aramid fiber is "poly-p-phenylene terephthalamide" (PPTA) fiber. It is an organic polymer fiber synthesized from terephthaloyl chloride and p-phenylenediamine. The amide bond is connected to two benzene rings. No. 1 and No. 4 positions, also known as Aramid 1414. The tensile strength of para-aramid is 6 times that of steel wire, 2 to 3 times that of glass fiber and high-strength nylon industrial yarn; the tensile modulus is 2 to 3 times that of steel wire and glass fiber, and 10 times that of high-strength nylon industrial yarn. ; Its density is only about 1/5 that of steel wire. Para-aramid has good impact resistance, corrosion resistance and fatigue resistance, and is referred to as "bulletproof fiber". The heat resistance of para-aramid is higher than that of meta-aramid. After hundreds of hours at a high temperature of 200°C, it can still maintain its original strength, and will not decompose or melt at a high temperature of 560°C. In terms of environmental protection, the stable and non-degradable properties of para-aramid fibers also determine the problem of difficult recycling and environmental impact in later stages.
02 History of Aramid Fiber
Aramid fiber was first developed by DuPont of the United States. DuPont developed a high-performance para-aramid under the trade name "Kevlar" in 1966, and began industrial production in 1971. In addition, the world's major manufacturers engaged in the production of para-aramid include Japan's Teijin Corporation, Russia's Heat Resistant Corporation, and South Korea's Kolon Corporation. Since the industrial production of aramid fiber in the late 1960s, aramid fiber has passed the transition stage from military strategic materials to civilian materials in the course of more than 40 years.
my country has started the research of aramid fiber during the "Sixth Five-Year Plan" period, but the key technology of industrialization has not been able to break through for a long time. The domestic demand for para-aramid mainly depends on imports. In recent years, with the continuous breakthrough of aramid technical barriers, the industrialization of para-aramid in my country has begun to flourish. At present, there are more than ten domestic enterprises in the industrialized production of para-aramid, including Sinochem Chenguang, Taihe New Materials, and Suzhou Zhaodat.
03 Market demand for aramid fiber
At present, the global demand for meta-aramid and para-aramid is 80,000 tons/year and 40,000 tons/year respectively. The production capacity is mainly concentrated in foreign companies such as DuPont in the United States and Teijin in Japan. The effective domestic production capacity of meta-aramid and para-aramid is 10,000 tons/year and 2,500 tons/year respectively. The domestic demand for para-aramid is more than 10,000 tons/year, and the import dependence is relatively high.
In 2017 and 2018, my country imported 3368 tons and 3392 tons of aramid fibers. With the broadening of downstream applications of aramid fibers, the high dependence of aramid fibers on imports will continue.
In summary, aramid fiber lags far behind foreign countries in terms of technology and output. It is not that the domestic market is not prosperous, but that it is extremely prosperous and therefore dependent on imports. From the perspective of market demand, aramid is definitely a fiber. The king of reinforcement materials, and the king of muffled fortune.