Aramid fiber is no stranger to composite materials (here, composite materials refer to resin-based fiber composites), because it is cost-effective, and it is destined not to be fully covered like glass fiber, nor is it extremely obvious like carbon fiber. Characteristics are widely used.
Aramid composite materials are widely used in general military industries, such as in fighter aircraft, bullet-proof armored vehicles, light tanks, bullet-proof banknote transport vehicles, and bullet-proof plates. During the Gulf War, aramid composite materials were heavily used on American and French aircraft. At the same time, in order to meet the needs of anti-terrorism, para-aramid fibers have been widely used in many developed countries' body armors, bullet-proof helmets, stab-resistant cut-proof clothing, explosive-proof clothing, and high-strength parachutes.
Aramid composite materials are also widely used in sports equipment, such as: preparing fishing rods, golf clubs, tennis rackets, bows, sleighs and other supplies to improve the life of these equipment.
Aramid fibers can also be used as coated fabrics, used in air-supported structures and inflatable rubber products, such as rubber boats, life rafts, soft airships, balloons, and special clothing. It can also be used in the fields of ships, aerospace, rail transportation and so on.
01Brief Introduction of Aramid Fiber
The full name of aramid fiber is “aromatic polyamide fiber”, which refers to a long-chain synthetic polyamide fiber in which more than 85% of amide bonds are directly connected to a benzene ring. , High temperature resistance, high strength, high modulus, insulation and other outstanding properties, is a new type of special polymer materials. Currently, there are two types of aramid on the market that have achieved widespread 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 "polyisophthaloyl metaphenylene diamine" (MPIA) fiber, which is an organic polymer fiber synthesized from isophthaloyl chloride and m-phenylenediamine. Because the amide bond is connected at the positions 1 and 3 of the two benzene rings, it is also called aramid 1313. Meta-aramid has long-term thermal stability, which is its most important characteristic. It can be used at 200 ° C for a long time without aging, and has excellent dimensional stability. Meta-aramid has inherent flame retardancy, and its limiting oxygen index (LOI) is> 28%. It will not spontaneously ignite and melt in the air, nor will it produce molten droplets. Meta-aramid has excellent electrical insulation. The insulation paper made with it has a breakdown voltage of 20kV / mm. Meta-aramid has excellent corrosion resistance and radiation resistance. In addition, meta-aramid has low rigidity and high elongation, and can be processed by conventional textile machinery.
Para-aramid has excellent properties such as high specific strength, high specific modulus, high temperature resistance, and flame retardancy. It is also known as the world's three major high-performance fibers with carbon fiber and high-strength high-modulus polyethylene. Para-aramid is called "poly-terephthalyl-p-phenylenediamine" (PPTA) fiber, which is an organic polymer fiber synthesized from terephthaloyl chloride and p-phenylenediamine. Positions 1 and 4 are 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 of the wire. Para-aramid has good impact resistance, corrosion resistance and fatigue resistance, and is known as "bulletproof fiber". Para-aramid has higher heat resistance than meta-aramid. After hundreds of hours at 200 ° C, it can still maintain its original strength. It does not decompose or melt at 560 ° C. In terms of environmental protection, the stability of para-aramid structure is not easy to degrade, which also determines that it is difficult to recycle and affect the environment.
02Aramid fiber development history
Aramid fiber was first developed by DuPont of the United States. DuPont developed the 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 para-aramid production include Japan's Teijin, Russia's heat-resistant company, and Korea's Kolon. Since the industrial production of aramid was realized in the late 1960s, in the course of more than 40 years, aramid fiber has passed the stage of transition from military strategic materials to civilian materials.
China has launched the research on aramid since the "Sixth Five-Year Plan" period, but the key technology of industrialization has not been broken for a long time, and 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 China has begun to flourish. At present, more than a dozen domestic companies are in the process of para-aramid industrial production, including Sinochem Chenguang, Taihe New Materials, and Suzhou Zhaodate.
03Market demand for aramid fibers
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 the United States DuPont and Japanese Teijin. The domestic meta-aramid and para-aramid effective production capacities are 10,000 tons / year and 2500 tons / year, respectively. Among them, the domestic demand for para-aramid exceeds 10,000 tons / year, and the import dependence is high.
In 2017 and 2018, China's imports of aramid were 3368 tons and 3392 tons. With the widening of downstream applications of aramid, the situation of aramid's dependence on imports will continue.
To sum up, aramid fiber lags far behind foreign countries in terms of technology and output. It is not that the domestic market is not strong, but it is extremely strong, so it is highly dependent on imports. From the perspective of market demand, aramid fiber is definitely a fiber. The king of reinforcements, and the king of muted wealth.