[Textile Knowledge] Understand Aramid Functional Textiles

Aramid functional textile project information

I. main contents of the project

Establishment of aramid fiber and product processing base

Two. Main characteristics and application status of aramid fiber

Aramid fiber is a kind of aromatic polyamide fiber. It is a new high-tech synthetic fiber. It has many excellent properties, such as super high strength, high modulus, high temperature resistance, acid resistance, alkali resistance and light weight. Its strength is 5~6 times that of steel wire, its modulus is 2~3 times of steel wire or glass fiber, its toughness is 2 times of steel wire, and its weight is only about 1/5 of steel wire. It does not decompose and melt at 560 degree temperature. It has good insulation and anti-aging properties, and has a long life cycle. It is a high temperature, high modulus, low density and wear-resistant high temperature resistant flame retardant fiber. Its technical content, high added value, excellent mechanical, chemical stability and mechanical properties, not only can be used alone for various structural materials and functional materials, but also can be used in combination with other materials. In addition, it also has good resilience and sealing performance. It is harmless to human health and environment. It can be used for sealing water, oil, hydrocarbon and medium acid base. The gaskets made have good sealing performance and creep resistance. It can be used as a substitute for asbestos for friction sealing materials, high performance heat resistant insulating paper and reinforced composite materials.

1. Main varieties of aramid fiber

The main aramid fibers are aramid fiber and para aramid fiber. The main aramid fibers are DuPont's Nomex, Tek's Conex and so on. The aramid fiber mainly includes Kevlar (DuPont), Technora (TEK), Twaron (TEK), etc.

2. Research and application status of aramid functional textiles

The unique physical and chemical properties of aramid make it widely used in high temperature, flame retardant, wear-resistant and high strength functional textiles. The world's research on it is also in the ascendant. New functional textiles are emerging one after another, and the application fields are constantly expanding.

Aramid fiber is an important material for national defense industry. In order to meet the needs of modern warfare, the bulletproof vest of the developed countries such as the United States and Britain is aramid material. The lightweight of aramid bulletproof vest and helmet has effectively improved the army's quick reaction ability and lethality. In the Gulf War, aramid composites were widely used in the US and French aircraft. In addition to military applications, it has been widely used in aerospace, electromechanical, construction, automotive, sporting goods and other aspects of the national economy as a high-tech fiber material. In Aeronautics and Astronautics, aramid fiber has a lot of power and fuel because of its light weight and high strength. According to foreign data, reducing the weight of 1 kilograms in the launching process of spaceship means reducing the cost of 1 million US dollars. In addition, the rapid development of science and technology is opening up more new civilian space for aramid. It is reported that at present, aramid products are used for about 7 to 8% of bulletproof clothing and helmets, about 40% of aerospace materials and sports materials, about 20% of tire frame materials and conveyor belts, and about 13% of high-strength ropes.

2.1 aramid flame retardant textile series

Although aramid fibers have good heat resistance and flame retardance, they are expensive. Secondly, due to high molecular crystallinity and strong intermolecular binding force, dyeing difficulties are caused. The high price and difficulty of dyeing inhibit their output and variety development to a certain extent. Therefore, various aramid blended flame retardant fabrics have been researched and developed to improve dyeing effect and reduce product price.

(1) the aramid and wool blended flame retardant fabric is a natural fiber with certain flame retardant properties. The aramid staple fiber is first made into strips, then blended with wool tops to form yarn, and then weave. When the aramid blend ratio exceeds 30%, the limit oxygen index reaches over 28. The fabric can achieve good and lasting flame retardancy without flame retardant finishing, and it can reduce the cost without affecting the appearance and comfort of the fabric. The blending ratio can be adjusted according to the purpose, and the multifunctional function can be realized.

(2) similarly, aramid and cotton blended flame retardant fabrics, in order to reduce costs and achieve multi-functional needs, a certain proportion of aramid and cotton fibers are blended to produce flame-retardant fabrics. In the study of aramid and cotton fiber blending, the blending ratio of aramid fiber to cotton is usually 80/20, 50/50 and 20/80. The continuous time, smouldering time and damage length of the 3 kinds of Mixture Fabrics meet the requirements of GB8965-88 grade two before and after washing. The LOI of the limit oxygen index is also greater than that of the 28 standard with flame retardant. The LOI value increased with the increase of aramid fiber content. Among them, 80/20 fabric has excellent heat resistance and flame retardancy. It can meet the requirements of national flame retardant clothing without flame retardant finishing. 50/50 and 20/80 blended fabrics need flame retardant finishing of Proban to meet the requirements of flame retardant standards.

(3) flame retardant viscose rayon blended with aramid and flame retardant viscose fiber is a fiber containing silicate. Its physical and mechanical properties are similar to those of ordinary viscose fibers, and can be processed into various kinds of textiles. Aramid and flame retardant viscose blended fabric has soft handle, good fluffiness, drapability, moisture absorption and permeability, high strength and abrasion resistance, good cloth finish, color fastness, and carbonization without carbonization. It can meet the quality requirements of high and middle grade flame retardant clothing and decorative fabrics.

(4) aramid and ramie blended flame retardant fabric is made of aramid fiber as core yarn, and ramie fiber is coated around it with ramie fiber to obtain ramie / aramid core spun yarn. In addition, the alkali treated ramie yarn is blended with aramid filament to produce composite yarn without twisting. After weaving the fabric, proper flame retardant treatment can achieve certain flame retardant requirements.

2.2 aramid antistatic functional textiles

Ordinary textile fibers, especially chemical fibers, are easy to generate and accumulate a large amount of static electricity. In the flammable and explosive environment, electrostatic discharge spark as ignition source often causes explosion accidents. At the same time, the vast majority of textile fibers are flammable or combustible materials. The limiting oxygen index is generally between 17~25, much lower than the minimum value of self extinguishing in air. 27, the fabric will burn quickly once it meets a fire source. In order to ensure the safety of workers in fire, petrochemical, ordnance, mining and many other fields, the fabric with flame-retardant and antistatic properties must be replaced by flammable and electrostatic fabric.

When aramid and conductive fibers form a new type of fabric in the way of blending and interweaving, the fabric has the durable protection function of flame retardant and antistatic due to the compatibility and complementarity of the fabric's flame retardancy and power dissipation. The latest aramid product Aracon developed by DuPont Co is using magnetron sputtering technology to form a thin film on the surface of aramid fiber, which not only has antistatic effect, but also shields high frequency radiation and signals.

Development of 2.3 aramid fiber dipped fabric

Aramid fiber (Kevlar) fiber dipped fabric is a new high-grade insulating material used for large motor. The process of two dip two rolling for aramid fiber fabric dipped. First, after the fabric is dipped, some glue is rolled out, so that the glue is immersed in the fabric gap, and then the glue is soaked into all the hairiness inside the fiber. Then second times of dipping is done. This time, the coating is mainly made, so that the fabric surface is covered with a certain amount of glue, and the second time rolling is to make the adhesive cover evenly, and then dry in the oven.

Because of its excellent performance, using aramid fiber as insulation material for motor can make the heat resistance grade up to 180 degrees Celsius. If mica is able to withstand high temperatures at 180 degrees Celsius, it will increase the weight of the motor because of its significant ratio, and the cloud parent material is brittle and the source is not abundant. The electric motor made of aramid fiber as insulation material can save 28% of copper, 15% of steel and 10% of silicon steel. The composites made of aramid fibers are lighter than 30% and 2 times higher than those made of the same method.

Application of 2.4 para aramid in bulletproof wear

The aramid fiber fabric has the highest anti dilatation strength, high modulus of elasticity and low specific density. It can absorb and disperse the energy absorbed by the bullet and transfer it to other fibers of the knitted fabric to avoid blunt injury. At the same time, the lightweight of aramid bulletproof vest and helmet has effectively improved the army's quick response ability and protection ability.

Study on reinforced concrete with 2.5 aramid / carbon fiber hybrid braid

Through the theoretical analysis and practical test of aramid / carbon fiber reinforced concrete, it can be seen that the function of fiber reinforced concrete is very obvious, especially using these two high performance fibers as load-bearing structure reinforcement materials, can replace the role of steel bar, and the weight is reduced by 41.8% compared with reinforced concrete. This is conducive to improving the seismic performance of buildings and the treatment of structure foundation, thereby achieving higher economic and bearing benefits. But how to facilitate the construction of fiber fabrics, and at the same time are easy to master by ordinary construction workers, still need to do more in-depth research.

2.6 aramid tire textiles

Because of the excellent performance of aramid fiber, the tire cord at high temperature is basically not affected by temperature. Under alternating stress, it has low internal friction, small calorific value and long life. Aramid can reduce the volume and quality of tire reinforcement, and minimize material and energy consumption, and raise some limit indicators to new heights. In addition, aramid fiber has no rust problem, and can replace all metal (including bead wire) in tire, so as to save rubber material, so that the tire performance can achieve light weight, low rolling resistance, fuel saving and dimensional stability, good uniformity, no flatness phenomenon, high speed performance, best traction and braking performance, good wear resistance, puncture resistance, easy disposal of waste tire and so on.

2.7 Kevlar weft free functional textiles

It is also used for bullet proof, and has better anti bullet performance compared with puncture free weft cloth and plain cloth. Because in the process of weft free manufacture, aramid fiber material has been fully developed, fixed by adhesive, and there is no interlacing point between fibers. When it is impacted by projectiles, it is conducive to dispersion of energy, more fiber can be involved, and energy can be absorbed on larger area, so its ballistic performance is better.

The density of aramid fiber and the mass fraction of matrix resin are all important factors affecting the elastic resistance of laminates. When the weft cloth has smaller surface density and lower matrix resin content, its laminates will have better ballistic performance.

2.8 aramid / carbon fiber non-woven fabrics

The aramid / carbon fiber non-woven fabric was produced by puncture process. Its oxygen resistance index LOI was 38~42, and the fireproof temperature reached 700 degrees Celsius. It is mainly used for fireproof and heat insulating interlining, high temperature filter, decorative interlining, fire-retardant splashing covering cloth, etc.

2.9 aramid / armor steel composite panels

Aramid fiber reinforced resin matrix composites are characterized by light weight, high strength, good elastic resistance and excellent flameproof effect. Aramid fiber reinforced composite plates can be used to enhance the anti knock performance of armored steel. The structure of materials will affect the shock wave attenuation effect of materials. When the material is arranged in a sequence of wave impedance reduction, shock waves can be more effectively attenuated. The material with multilayer structure has better attenuation effect than bilayer structure material, and a protective material with excellent anti knock performance can be obtained.

Three. Development direction of aramid fiber

In accordance with the "12th Five-Year plan", during this period, China's 1000 ton grade aramid fiber production technology will break through and will enter a rapid growth period, thus leading to the rapid development of related industries. Focusing on the strategic emerging industries, major projects of national economic construction, national defense industry and upgrading of materials industry structure, China Chemical Fiber Industry Association has focused on the demand for downstream main application areas, the self-sufficiency rate of products and the main varieties needed to import. In the next 10 years, domestic automobile, telecommunications, high-speed railway, aviation and protection will develop rapidly, and the demand for aramid fiber is booming. At the same time, the transfer of foreign downstream processing enterprises to the domestic industry will also stimulate the growth of domestic demand for aramid fiber. In 2015, domestic demand for aramid fiber will exceed 10000 tons, and in 2020 it will exceed 20000 tons. Among them, domestic demand is predicted to be 2000 tons, 1000 tons of high strength type, 2000 tons of high Model 2000 tons, 2000 tons of aramid staple fiber and 3000 tons of para aramid pulp. In addition, by 2015, the domestic supply of aramid will reach 50%, reaching 80% in 2020.

Four. Development of aramid fiber products

According to the characteristics of aramid special fabrics, the following products can be developed:

1. Bullet proof camouflage suit, stab proof vest, bulletproof bulletproof helmet, tank suit, bulletproof shield, racing suit, etc.

2, anti cut clothing, explosion proof clothing, anti stab clothes, anti cut bags, etc.

3. Headgear, gloves, socks, etc.

4, children and the elderly labor protection products

5, pajamas

6, aramid non-woven fabrics

7, public safety equipment, transport safety packaging, and protective devices for vehicles and aircraft.