Aramid Rubber reinforcement and matrix materials

Abstract: The rubber-reinforced matrix material and para-aramid-dimensional performance characteristics, uses, and domestic and foreign production and research and development, pointing out that its development prospects in China.
Keywords: aramid; para-aramid fiber; preparation; application

Aramid called the poly-phenylene terephthalamide phenylenediamine, referred to as para-aramid fiber (PPTA), is a high-tech fiber material aramid fiber is the most representative, and carbon fiber , high strength and high modulus polyethylene fiber and said the world’s three major high-performance fibers. Of which more than 85% of the amide linkages are attached directly to two aromatic groups. Aramid polymer is a high rigidity, its molecular structure with a high degree of symmetry and regularity, forming strong hydrogen bonds between macromolecular chains, it has high strength, high modulus, high temperature, low density, heat shrinkage, good dimensional stability, etc., are widely used in critical aerospace, security, backbone equipment, transportation, and automotive manufacturing structure enhancement is an important raw material on the basis of national security and national economic development.
Currently, aramid main types: (1) Kevlar 14, that PBA fiber, also known as domestic aramid I; (2) Aramid 1414, namely terephthalic terephthalamide fiber (PPTA), the country also known as Kevlar II, on behalf of products DuPont Kevlar and Teijin’s Twaron; (3) polyol copolymer aramid, on behalf of products produced by Teijin Technora; (4) a heterocyclic aramid. Such aramid polymer main chain contains an aromatic heterocyclic unit, the representative of the Russian products are produced APMOC, SVM, RUSAR and China’s production of Kevlar, etc. III.
Aramid first by DuPont in the 1970s successfully developed and industrial production. For a long period of time, only a very few countries, the United States and Japan, with production capacity. Japan and the United States almost monopolized the global market for aramid. Since the military, science and technology has a special purpose, para-aramid fiber has been listed as an important strategic material, production technology by the blockade, but also to achieve tighter control on trade. At present, China’s demand for aramid mainly rely on imports. With the acceleration of China’s modernization process, and related fields aramid demand urgent Yu hair, break the international monopoly, to achieve localization of the product have become major issues need to be resolved.

One pair of the main characteristics of the aramid
In the existing high-performance fiber, aramid fiber is one of the best overall performance of the organic, its most prominent features are high strength, high modulus and high temperature, but also has a wear-resistant, flame resistance, chemical corrosion, insulation, anti-cut, anti-fatigue, flexibility and good dimensional stability and other properties.
(1) mechanical properties. Aramid most outstanding mechanical properties is its high strength and high modulus, which is 5-6 times the strength of steel, modulus of 2-3 times the wire or glass fiber, toughness is 2 times the wire, while the weight only about 0.2 times that of steel.
(2) thermal performance. Aramid has a high glass transition temperature and thermal decomposition temperature was above 270 ℃ and above 430 ℃, the maximum reached 360 ℃ and 600 ℃. Aramid thermal shrinkage rate is very small, at 150 ℃ contraction rate is zero; aramid at high temperatures also have high strength retention, as experience at 160 ℃ still maintain the original strength after 500h 95% at 200 ℃ still maintain 75% of the experience of the original strength after 100h, at a temperature of 260 ℃ can still maintain 65% of the original strength.
(3) flame retardancy. Aramid having a higher combustion temperature and LOH (limiting oxygen index) value, extremely difficult to burn in air, automatically turns off after leaving the flame. At high temperature 500-600 ℃ is also difficult to ignite, it is a good fire-retardant material. Wherein LOI value heterocyclic Kevlar para-aramid is the highest, reaching 37% to 43%, significantly higher than other types of para-aramid product.
(4) Weather resistance. Benzene and other para-aramid polymer, like ultraviolet, electron beam is extremely sensitive, but to a lesser degree of influence on visible light. 300-450nm wavelength of light is easily absorbed aramid, it can lead to cleavage of an amide group, resulting in decreased strength, while the color will darken.
(5) creep. Aramid due to its high crystallinity and one-way, so the creep resistance is very low. Creep and stress related to the level of size and temperature between 20-150 ℃, if the stress is less than 50% of the tensile strength of aramid creep rate is not due to stress magnitude and temperature level vary , if the stress is higher than 70% of the tensile strength, creep rate increases will accelerate.
Although aramid has excellent overall performance, but there are also compression modulus and low compressive strength, intolerance alkali, moisture, and resin-bonded interface is bad and other shortcomings.
Two pairs of aramid applications
Aramid material application mainly around its high strength, high elastic modulus and other excellent features expanded. According to reports, aramid products are used in bullet-proof vests, helmets and other accounts for about 7% -8%, aerospace materials, sports materials account for about 40%, respect for tire reinforcement, conveyor belts and other materials account for about 20%, further there are other aspects of high-strength rope approximately 13%.
2.1 Application in the field of ballistic
Para-aramid fiber is an important national defense materials. To meet the needs of modern warfare, at present, bullet-proof vests United States, Britain and other developed countries are aramid material, Kevlar body armor, helmets lightweight, effectively improve the army’s rapid response capability and lethality. Para-aramid fiber anti-ballistic impact resistance thanks to its excellent thermal stability, high crystallinity, highly oriented structure and high tensile properties. High glass transition temperature and excellent thermal stability of aramid fibers at the high temperatures generated by the ballistic impact can ensure the stability of the structure; highly crystalline, highly oriented to produce a high modulus, to ensure that the axial rapid response deformation; high elasticity and moderate elongation so that para-aramid fiber with high toughness, so that when the longitudinal fracture can work effectively.
2.2 Application in the tire field
In the automotive tire industry, as the excellent performance of aramid reinforced rubber and reinforcing materials, much domestic and international rubber and tire industry concern, in particular the production of ultra-light, ultra-thin and low rolling resistance radial tires with Kevlar cord . From the dynamic mechanical analyzes, aramid modulus increases with increasing temperature, but the loss modulus decreased with increasing temperature, so the para-aramid having excellent high-temperature performance; It also has a relatively small hysteresis loss, tread distortion, reducing the heat formation, low rolling resistance, excellent high-speed performance. Compared with steel, polyester cord, aramid cord with high temperature, high strength, high modulus and deformation characteristics, but also has a relatively low density, resistance to fatigue, shear flexibility, both the wire, artificial silk, nylon, high performance polyester cord, the “synthetic wire,” said, is the best framework material. Will aramid radial tire for passenger cars of the belt layer, can reduce tire rolling resistance 5% -7%, reduce fuel consumption; for truck tire carcass quality can be reduced 2.4-5.2kg, the air temperature inside the tire steel tire lower than 5 ℃, tread life expectancy of 12% -14%, fuel economy increase of 1.25%; for truck tire belt layer, the quality can be reduced 5.5-6.7kg, better impact resistance with the same beam intensity when the fracture energy is 20%; for bias truck tires, compared with nylon, tread life expectancy increased by 20% -25%; for aviation tire belt layer, excellent wear resistance; for OTR tire, get a good cut resistance, in particular, have a good anti-puncture resistance, cut resistance, wear resistance is greatly improved, both the para-aramid material toughness and rigidity (rigidity is 4-6 times that of steel, toughness It is 2 times stronger than steel), and the molecular structure rendered inert to chemical and physical attack has a good resistance, can increase the number of retread tires. Kevlar cord and rubber bonding effect than steel is good, and is not susceptible to moisture and humidity. Therefore, the para-aramid fiber tire cords obtained at high temperature mechanical properties substantially unaffected by temperature, low friction in the post under the stress change, heat a small, long life, can reduce the volume and quality of tire reinforcement materials, but also to minimize the energy consumption of the material. This improved tire performance improvements this can greatly improve their quality, enhance competitiveness, and limit the number of indicators to a new height. In recent years, instead of Kevlar cord nylon cord, achieve weight reduction became aviation aircraft tire tire manufacturers competing priorities. Currently, Michelin, Goodyear, Pirelli, Guper other famous international tire companies in recent years have introduced the use of para-aramid new tires. South China Rubber Tire Co., Ltd. has been applied to produce a high-performance aramid car radial tires. Shandong Hailong Bolet Chemical Fiber Co., Ltd. and DuPont established a strategic cooperative relations of production and the market, at present, the company has successfully developed and Kevlar aramid ply composite ply performance can be designed (including Kevlar / polyester, aramid ) nylon composite two kinds of products). China Shuguang Rubber Industry Research Institute and Beijing Rubber Industry Research and Design Institute have jointly developed aviation radial tire, to achieve a “zero” breakthrough of aviation radial tire, but also can achieve the skeleton of the material Kevlar.
2.3 Application domain led
Conventional hose reinforcing material used in steel wire and nylon, polyester, rayon and other fabrics. Due to the development trend of the hose to withstand higher pressure and temperature, and can adapt to the harsh working environment, thus requiring hose reinforcement layer not only temperature and pressure, but also it should have excellent performance.
Currently, high pressure braided hose, a para-aramid braided hose share increasing, and the demand for an upward trend. Kevlar braided hose has the following characteristics and advantages of such aramid fiber reinforced hose become the best choice of materials. (1) specific strength and specific modulus than steel, nylon and polyester fibers is much higher, because the wire does not produce an internal fracture stabbed external protective layer testimony led to the failure from happening; small (2) Elongation at break , volume change when a small load hose; (3) abrasion resistance, excellent flex resistance when, without causing the hose and the hydraulic shock generated by the bending fatigue degradation; (4) weight. Weight is about 1/3 of the steel braided hose.
Hose with a reinforcing material, from the pressure and taking into account the density, specific strength and specific modulus, heat resistance and processability and other key Inso, para-aramid fiber is the main direction of development. Aramid reinforced hose related research since the late 1970s, at the international level, a growing number of automotive hoses, chemical industry hose, hose oil industry, aviation industry with a variety of hydraulic hoses marine hoses are used as well as para-aramid fiber as a reinforcing material.
2.4 Application of high strength rope field
Para-aramid fiber is through a special process of polymerization, stretching, spinning a high temperature strength fibers. Para-aramid fiber produced by the rope large number of applications in various fields, such as slings, cable, large special ships, military cable ropes, cables, power engineering and other work, and the pH of the ocean and of special operations for pH3-9 inorganic solution is not compromised, adapted to -40-350 ℃ low temperature operation and the like.
2.5 Application in aerospace materials and sports material
Para-aramid fiber with a low density, high specific strength and specific modulus, abrasion resistance, impact resistance, flame retardant and other characteristics, widely used in aviation with high-performance materials, aircraft cabins, body structure applications such as Kevlar composites.
In aviation, aerospace side, aramid strength due to the high quality of light, save a lot of power fuel. According to foreign data show that in the spacecraft during launch, each weight lkg, which means reducing the cost of $ 1 million. In addition, the rapid development of science and technology is to open up a para-aramid more new civil space. Para-aramid fibers can be used for primary structural materials for airplanes and helicopters, such as the cabin door, window, body fairing, ceilings, bulkheads, air replied, storage cabinets, etc., such as landing gear doors for the Boeing B757 aircraft Kevlar composites. Aramid also has excellent dielectric properties, mechanical properties and high dimensional stability, making use in airborne, shipboard and spaceborne radar radome, radar antenna feed member function and light antenna support structure .
2.6 Application in the field of electrical and electronic
Para-aramid fiber has excellent mechanical properties, electrical insulation properties, transparent wave performance and dimensional stability. It has been applied in the field of electrical and electronic surface mount technology printed circuit board with a special assembly in microelectronics technology. Airborne or spaceborne radar radome, radar antenna feed function structural components and electrical components, and many other sports. American company RCA satellites developed multiple parabolic antennas, which are made of reflective surfaces para-aramid fiber fabric reinforced composite materials.
3 Production and Development Overview abroad aramid
Aramid by the DuPont company in the 1960s, the successful development of industrial production in 1972, the trade name Kevlar, an initial production capacity of 2,000 tons / year, then gradually expand production capacity in 2010, production capacity will reach 36,500 tons / years, respectively, in the United States, Japan and the UK has a production plant.
Dutch Akzo Nobel company in 1987 after the industrial production of para-aramid products Twaron, production capacity of 5,000 tons / year in 2000, the company acquired Teijin Twaron Netherlands conducted several large-scale expansion in 2010, annual production capacity of 2.30 tons / year.
Korea Cologne (Kolon) began in 1979 aramid development, commercial production began in 2005, under the trade name Heracron, 2010 an annual production capacity of 2,600 tons / year. Hyosung achieve the industrialization of aramid fiber production in 2009, 2010, annual production capacity of 1,000 tons / year.
Russia has committed heterocyclic aramid research and development and production, in 1972, SVM Leningrad branch were semi-industrial production, in 1979 to establish production base in Gdansk Carmen chemical fiber plant and industrial production. Russia built 100 tons / year in 1985 aramid pilot production line, trade name Terlon. The late 1980s and early 1990s, the Russian Institute also conducted a Rusar fiber research and development, and achieved success. Heterocyclic aramid major study by the research and production association and the St. Petersburg Academy of fiber composites suburbs of Moscow, and a large concentration of production in the chemical fiber Intervet Lane J / S Company and Carmen Gdansk (Kamensk) Fiber Company. In 2010 total production capacity of the Russian heterocyclic aramid about 2,000 tons / year.
By the end of 2010, total overseas production capacity to approximately 70,100 tons of para-aramid, where DuPont is the largest manufacturer, the production capacity of 36,500 tons / year, 52.07 percent of the total production capacity; followed by Teijin company production capacity of 26,000 tons, accounting for 37.09% of the total production capacity of other countries and only a small amount of production companies.
The current international para-aramid based on the characteristics of the development of advanced technology to promote the application of the upgrading of products. To this end, Calvary companies racing to develop new products, para-aramid. DuPont has developed a series of new varieties of para-aramid, such as ultrahigh strength type Kevlar129, strength 20% higher than Kevlar29, toughness stronger; the development of the advanced nature of the fiber Kevlar K29AP grade strength than standard K29 fiber strength up to 15 %, can be applied to the automotive industry include tires, belts and hoses, construction, oil, gas and utilities composite materials and electro-mechanical cables. Ultra high modulus type Kevlar149, modulus compared Kevlar49 increased by 25%, while only 25% -50% moisture regain ordinary PPTA fibers; medium modulus type Kevlar68, high bonding type Kevlar-Ha, anti-fatigue type of Kevlar. Development KevlarXP, use it made of bullet-proof vests after 10% weight reduction, but also to reduce the impact of the bullet 15%; the development of high strength and high modulus Kevlar tow Kevlar49HS, activation for bonding aramid rubber industry silk Kevlar Ha, police body armor fabric Kevlar Protera ultrafine Kevlar, its strength of 24.4cN / dtex. In addition, DuPont has developed a series of new varieties of aramid, such as Kevlar Aracon new products, with a metal coating on the surface of aramid fiber, with the elimination of static electricity, radiation shielding, electrical signal transmission function, quality than the metal wire light and soft. Kevlar M / B concentrate pulp and Kevlar reinforced elastomer, aramid pulp or short fibers will be processed into rubber premix products for the hose tape and rubber tires can enhance wear resistance and tear resistance. In addition, DuPont also continue to open up new application areas, the development of high-strength lightweight Kevlar fiber to improve the protection and functionality, the company maintained its leading position in the fiber market.
Teijin newly developed products SulfronTM, tire rolling resistance can be reduced by 20%, which means a 5% reduction in fuel consumption. Germany Acordis company recently developed a high-performance ultra-fine aramid, neither burn nor melt, as well as high strength and great resistance to cutting capacity, mainly for the production of coatings and non-coated fabrics, etc. both knitted and needled felt heat and cut resistant variety of textile and apparel equipment. Teijin has developed a dedicated hose and conveyor belt are reinforced Kevlar strands Twaron1014 and Twaron1015, compared with the standard model Twaron1008, in addition to the mechanical properties more suitable for hose and belt requirements, both products also through the activation process only need to step dipped rubber matrix adhesion and good time applications. Twaron2100 belt is designed for the development of Kevlar tow, compared with the standard Twaron1008, it has a relatively low modulus, improved resistance to bending and compression fatigue performance, excellent dynamic performance. Twaron2300 is designed for high-performance power hoses and belts development, characterized by both high strength and tensile strength of collusion. Ultrafine Kevlar bulletproof dedicated Twaron1008CT, can significantly improve the ballistic performance. Teijin developed Technora T700 fibers, which are three times the impact resistance of carbon fiber, aramid fiber modulus is twice II, the adhesion of the fibers and the resin increased by 10%, as a reinforcing material of carbon fiber composite materials, improvements impact strength. Russia heterocyclic aramid also continue to develop new products, such as Artee fiber, high strength 35Cn / dtex, modulus 200GPa, after the epoxy resin impregnated fiber strength is 5.39GPa.
Production and research and development status quo of para-aramid of 4
China from the 1970s began to invest a lot of manpower, material and financial resources to develop Kevlar technology, but in the key engineering technology has not achieved a breakthrough, the domestic demand for aramid mainly relied on imports, severely restricted in people . Aramid long-term supply shortages, largely restricted technological progress and industrial upgrading of China in related fields. In recent years, with Kevlar technology continues to break barriers, China’s para aramid industrialization began to flourish. At present, there are more than a dozen companies being aramid industrial development, including Sinochem dawn, Yantai Spandex, Henan Pingdingshan Shenma, Yizheng Chemical Fiber, where Silicon Valley North, chemical, and Guangdong Charming like.
Chenguang Chemical Research Institute Co., Ltd. aramid research and development has been at the forefront of localization. In terms of the heterocyclic Kevlar, dawn hospital after years of research and development, breaking a number of technical difficulties, has achieved 5t / stable production, a Kevlar fiber strength reaches 4. 5GPa III above, the product has passed the national acceptance, and in some on some models of weapons successful localization instead. In terms of aramid II, Chenguang Chemical Research Institute has solved the continuous polymerization of the liquid crystal and high-speed dry and wet spinning of the key technical problems, and the completion of 30 tons / year pilot production line. In the Kevlar aramid II and III of the research and development process, dawn hospital has accumulated a wealth of practical experience in research and development and engineering, it has applied for patents, with independent intellectual property rights. Mid-2009, Chenguang Research Institute Ltd. in Chengdu Xinjin Industrial Park began building the capacity of 1000 tons aramid fiber project is expected to be put into operation by the end of 2011 means.
China’s largest specialty fiber production base in Yantai Spandex Co., Ltd. aramid research and development has also made significant progress. 2004 Yantai Spandex Co., Ltd. officially launched a pilot study on the development of aramid filaments and pulp technology, the project was included in the year in Shandong Province major scientific and technological programs. Built in 2007 pilot production line 100 tons, breaking the aramid core and key technologies, the formation of independent intellectual property rights, and passed technical appraisal by experts of Shandong Province Science and Technology Department. In 2008, the company launched a 1,000 tons / year of aramid engineering project, supported by the National High Technology Research and Development Program (863 Program) of key projects, “para-aramid high-tech industrialization demonstration project” National High Performance Fiber Composite materials special programs, independent innovation achievements, Shandong Province, major projects, and the strong support of Yantai Development Zone in Yantai City of science and technology projects. 100-ton pilot line for the kiloton-scale production process improvement data, and explore the accumulated experience in production management provides a good platform, at the same time, the use of pilot product market development, in personal protection, enhanced cable, hose skeleton, reinforced base cloth, packing seal and enhanced cable and other areas of applied technology systems and feedback constantly optimize the technology according to the market for the production line kiloton commercial success laid the foundation. 1000 tons / year aramid industrialization project in October 2009 officially started construction of the project with a total investment of 2.5 billion, in May 2011 to produce qualified products. The plant aramid kiloton industrialization projects successfully put into operation, making China Yantai Spandex Co., Ltd. became the only production-scale inter-aramid, para-aramid fiber products Aramid industrial base for meeting our science and technology, security, transportation, communications and other areas of the urgent need for high-performance fiber materials, revitalization of China’s national industry has an important role in promoting.
Donghua University in 2000, after the start of work on the para-aramid fiber in 2006, and two private companies set up on Haiaimaida fiber Technology Co., Ltd., and Changshu Best Leather Co., Ltd. annual output of 100t scale pilot plant. In 2007 the project through the identification of Chinese Textile Industry Association.
April 2008 Luna horse group aramid fiber project by the Science and Technology Department of Henan Province in achievement appraisal organized by Beijing, Shenma get through all of the production process, the first in China to produce a performance close to the international advanced level of para-aramid. End of February 2009, China Pingdingshan Shenma Group’s original annual production capacity of 500 tons means on the basis of aramid fiber production capacity will be expanded to 1,000 tons, the plant is expected to be completed in 2011.
The end of 2008, Sinopec Yizheng Chemical Fibre Company Limited 3,000 tons of para-aramid means to start construction in Yizheng City, Jiangsu Province, means a total investment of 1.1 billion yuan, the main project including 3,000 tons of para-aramid, para-aramid 3000 t filament spinning apparatus and 30,000 tons solvent recovery. It is expected to put into operation in 2012.
In addition, Guangdong Charming Co., Ltd., Hebei Silicon Valley Chemical Company, Henan Pingdingshan Shenma Group, Changshu Suzhou Science and Technology Co., Ltd. trillion Dart fibers are also plans to build a certain size or para-aramid production unit, 2015 China’s production capacity of aramid will reach about 1.5 million tons, becoming the world’s major producing countries para-aramid. Will largely meet the domestic demand.
5 pairs of aramid Development Prospect in China
Aramid as an important new material, supported by national policy, in October 2010, the State Council promulgated the “decision to accelerate the development of strategic new industries” clearly proposed to focus on the development of high-performance fibers and aramid composite materials and other new materials. The next 10 years, the domestic automotive, communications, high-speed railway, aviation and protection and other fields will be rapid development, the demand for aramid exhibits strong situation. At the same time, foreign domestic downstream processing enterprises to carry out the transfer of industries, will stimulate domestic demand for aramid growth. 2015 Our demand for aramid will be more than 10,000 tons in 2020 to more than 20,000 tons. Thus, the para-aramid in our country has a good market prospect, around the strategic emerging industries, the construction of major projects in the national economy, national defense, industrial upgrading and adjustment and other material structures. The next few years of para-aramid fiber production capacity will usher in a phase of rapid promotion. Furthermore, according to the “second five” plan, in this period, China kiloton aramid production technology will be transferred to achieve a breakthrough and rapid growth, which led to the rapid development of related industries.
Although China is also a para-aramid localization of research and development, and has made some progress, but the production of para-aramid engineering of key technologies, the main raw material production technology and key equipment manufacturing technology and other issues has not been solved, China’s localization process aramid still relatively slow, productivity is not high, China’s largest existing production capacity of aramid enterprises can not exceed 1,000 tons / year, the product is not stable, It does not have the scale of competitiveness. Such as aramid II industrialization, although aramid II (ie Kevlar 1414) used at home and abroad are basically the same technology route, are to NMP as a solvent condensation terephthaloyl chloride and p-phenylenediamine twin screw continuous polymerization prepared high viscosity polymeric resin was washed with water, dried and dissolved in concentrated sulfuric acid and subjected to dry-jet wet spinning, then after the final product is obtained by stretching, washing, heat treatment step, but in the domestic aryl there Lun industrialization process many problems, there is still a gap compared with foreign, in particular in poor equipment performance, low productivity, unstable performance, capacity, less variety, low degree of serialization. In addition to the standard grades such as DuPont Kevlar29, but also developed a Kevlar49, Kevlar68, Kevlar129, Kevlar 149 and KevlarXP and other grades, each grade there are a variety of specifications, and our successful development of similar Kevlar29 mostly level, but also a small amount Kevlar49 similar products, product serialization low level, less product brands, domestic production can not meet the actual demand, and has good development prospects. Therefore, the state should intensify macro-control efforts, concentration of superior forces to accelerate the industrialization of aramid pace. Meanwhile, in order to break through the key technologies as soon as possible, to achieve special equipment and aids localization, countries need to continue to increase its focus on scientific and technological project funding to support efforts through research with the Union, etc., to promote scientific and technological achievements into productive forces quickly and thus foster more complete on the downstream industry chain, enabling the aramid true localization. But it should be noted that the para-aramid products relative to other conventional chemical products is concerned, has the characteristics of high-tech, high capital threshold and high market risk, which is the downstream market is limited to the development and application of high performance materials minority areas, therefore, the national authorities should co-ordinate the planning, development should not be blind to avoid cannibalism situation, the impact of para-aramid and steady and healthy development of related industries.