Technology Practice and Discussion of aramid yarn

Published on 2018-06-21
This paper introduces the aramid fiber and flame retardant viscose characteristics and uses, and to address the phenomenon wound two fibers blended spinning process due to static electricity caused by too much, we discuss the presence of spinning problems, and proposed follow-up technical difficulties need to be addressed.
Keywords: aramid fiber flame retardant viscose vector staining functional mini
      With the improvement of people's living standards, people are increasingly demanding clothing tends to be diversified, stylish, is one goal, our successful use of aramid fiber and flame retardant viscose blended yarn spinning 30 , recognized by customers, while ensuring the security of full soft, comfortable, breathable, dyed bright, good antistatic characteristics, to ensure blended after reaching optimum performance.
First, the fiber characteristics and uses:
Kevlar Features:
      1, good mechanical properties: aramid polymer material is flexible, low stiffness and elongation properties so that with the same regular fiber can be spun using conventional textile processing into a variety of fabric or non-woven fabric, and Kevlar wear-tear fabric can be widely used in the field of special labor protection, military production.
      2, excellent flame retardancy, heat resistance: aramid fiber is a flame retardant fiber, limiting oxygen index LOI value ≥28%, belongs to the flame fiber, aramid fabrics so will not burn, melt or produce in the air droplet, do not emit harmful gases, not combustion, there are self-extinguishing.  
      3, stable chemical properties: thermal stability at 220 ℃ high temperature can be used without a long-term aging, the effectiveness of the electrical and mechanical properties can be maintained for 10 years, and excellent dimensional stability.
      4, radiation resistance Meta-aramid fiber resistance α, β-ray and ultraviolet radiation performance is very good. For example, in the amount of β-ray radiation accumulated to 1000 Mrad, its intensity remains essentially unchanged.
Aramid fiber use
      Applied to all aspects of the aerospace, electronics, construction, automotive, sporting goods and other economic sectors, mainly for labor protection, fire service, fire boots, fire and other consumer packages with special equipment fighting suits, flight suits, anti-chemical warfare suits radiation protection high-performance military clothing and other apparel and other industries, is a new high-tech synthetic fiber, with high strength, high modulus and high temperature, acid and alkali, light weight
Retardant viscose fiber performance:
     (1) Good permanent flame retardant
       (2) excellent heat insulating properties. Effectively prevent the high-temperature thermal radiation transfer. High temperature fibers do not shrink, no deformation.
       (3) anti-arc and antistatic properties. Keep the original natural viscose fiber antistatic properties.
       (4) excellent absorption of humidity. Breathable wearing comfort. High temperature environment conducive to sweat.
       (5) good dyeing properties. Easy color has natural fiber, dyed bright, color fastness and good.
       (6) Green. Natural regeneration of plants as raw materials, natural degradation of waste, comply with environmental requirements. Phosphorus-based flame retardant halogen-free in line with EU requirements
Retardant viscose fiber uses:
      1 is an inherently flame-retardant anti-droplet performance of new high-tech fiber materials. Compared with the synthetic polyester flame retardant fiber, the fiber product not only ensures excellent physical properties, but also to achieve a low-smoke, non-toxic, no smell, no melt dripping characteristics. With the development of domestic and foreign retardant mandatory regulations coupled with the improvement of people's awareness of fire safety. Applications flame retardant textiles widening extends to the home, underwear, and other fields, flame retardant textile requirements from a simple extension of protection to the pursuit of better comfort, breathability and performance.
      2, aramid fiber and flame retardant viscose main physical indicators:
Fiber category fineness length dry strong resurgence
Aramid 2.2 dtex 44mm 3.9 5.5
Retardant viscose 1.7 dtex 40mm 1.8 9.13
      3, process optimization:
       According to the characteristics of the product, combined with multi-component fibers of different processing capability, research a reasonable ratio, optimized spinning, weaving and dyeing process, preferably yarn, twist, tension on the machine, the amount of additives added and other parameters to ensure product quality to meet fabric requirements.
     4, the spinning process:
     Pigment preparation 4.1
     So times to customer requirements color yarn, so the need for dyeing aramid, aramid dyeing Discussion follows: aramid dyeing using now most of them are using a carrier staining, dyeing polyester and almost all require high temperature and pressure. The merits of dyeing method lies primarily aramid dyeing carrier selection, carrier selection principles are: to promote better dye effect, the amount is less, to be non-toxic and odorless. 50 degrees after adding aramid fibers pretreated carrier HPS-505, run 10 minutes, warmed to 70 degrees, a cationic dye was added, run 10 minutes, was added sodium nitrite (sodium chloride) was run for 10 minutes and then 1 degree / min heated to 130 degrees and incubated for 60 minutes in 1 degree / min, cooled to 75 degrees, the color, draining and cleaning.
Retardant viscose fiber blends with raw white
     4.2 Processing of raw materials
     Because aramid fibers dyed than resistance, electrostatic phenomenon seriously, fiber pretreatment improper easily around the cylinder, and Wick spend no less than sliver, wrapping rollers, etc., so the need for raw materials for health treatment, adding some antistatic agents drink water, health and strictly enforce the time (the need to ensure more than 16 hours, and placed at 28 degrees, relative humidity of 65% of the environment).
      White masterbatch flame retardant viscose because cellulose fibers, carding process in order to avoid the formation of white knot, so the fibers can not refuel water regimen after regimen aramid material with flame retardant viscose be blended.
     4.3 Process:
     Because both fibers and viscose aramid electrostatic relatively large and relatively fluffy consistency of good fiber length in order to reduce damage to the fiber spinning is decreased, we use short spinning process, process:
And Mao BC262 → (automatic feeding cotton) carding head and FA306 → A186 → FA306 → two and three and four and FA306 → FA306 → roving FA458 → automatic winding yarn FA506 →
     4.4 Problems in the spinning process and technical parameters
     4.1.1 Carding technical measures  
     By aramid fiber and flame retardant viscose fibers are, fiber uniformity, less impurities, electrostatic phenomenon seriously ,, carding process must ensure less damage to the main opening and minimize back and fight over flower multi-junction resulting increase. Carding strips should be mainly to solve the difficulties, blocked chute and ensure the transfer of the fibers, to enhance the ability of the fibers of the transfer, a cylinder cover interval is 0.35mm, 0.35mm, 0.30mm, 0.30mm, 0.35mm than cotton spinning process large sliver quantification of 17.5g / 5m, the upper and lower roll spacing distance of 0.20mm, compared with the large spinning cotton, improve the smoothness of each channel, reduce congestion broken bars. Cylinder speed 330r / min, licker speed 780r / min, the cover rate of 81mm / min, large road speed is 17r / min, after the above process machine spun cotton sliver became 4, clear webs degree good, smooth and delicate sliver appearance.
      Article 4.1.2 and process technology measures
      Since the aramid fiber has a slight electrostatic and flame retardant, mainly to solve the production of the winding roller rubber roller phenomenon, the main measures are:
     (1) and Article Cots with WSN-based paint, better than acid-treated rubber roller;
      (2) the low vehicle speed control, small bell master, improve sliver cohesion;
      (3) the full length of the barrel by a 2km to 1.6km, reduce the friction and the sliver coiler surface.
     Article merging and using four, front roller line speed of 190m / min, bell 2.4mm, sliver quantitative 19.5g / 5m, roller gauge 9 X 15 X 20mm.
4.1.5 roving technical measures
     Reasonable choice roving twist factor, it is necessary to improve the cohesion between the fibers, but also to prevent a roving "hard head" phenomenon, the preferred twist factor as 71. When small spinning yarn tension control in order to reduce accidents yarn elongation.
     Roving quantification of 5.5s / lom, 7.09 times the total draft, front roller speed is 180r / min, roller gauge 10 X 26.5 X 3lmm. spinning process technology measures
     Spinning total draft 30.83 times, 1.32 times after drawing, twist factor 376, front roller speed 183r / min, roller gauge 18 x 24mm, jaw gauge block 3.0mm.
     After testing, spinning yarn indicators: + 1.6% weight deviation, CV value 14.34%, details 5 / kin, slub 55 / km, Nep 145 / km, breaking strength of yarn 17.58cN / tex, a strong CV of 9.8%.
     From the yarn quality point of view, in addition to cotton Festival slightly, the other good indicators. We believe that the main reason for a relatively large section of cotton is a relative slip between the fibers of the sliver drawing kink caused, still need to overcome.
     4.2 As the aramid fiber is very fluffy, elastic, high elongation, and a static agglomeration during processing; flame retardant viscose fiber low wet strength, abrasion resistance is poor, poor cohesion between the fibers, to push Ao difficulties, fluffy yarn, difficulties exist high rate of breakage when spinning, the following measures should be taken in the spinning process:
   (1) when spun Kevlar to maintain high humidity, to avoid static accumulation, carding a relative humidity of 65%, and of the 62%, 58% of the yarn.
    (2) due to aramid fiber length of 44mm, roving twist too easily, with smaller and smaller quantitative draw ratio improved yarn neps improve the evenness. Yarn twist factor appropriate to increase, the general control 370.
    (3) small winding tension control, the use of chemical fiber splicer, because fibers are more flowers, so the winding joint force must ensure that 85%, a good appearance.
    (4) Since the light fastness of dyed aramid fibers after only three subsequent need to continue this research.