Ease of surface dyeing
Staple fibers made of polyacrylonitrile are used for the production of acrylic yarns.
Acrylic, invented in 1941 by the American concern DuPont, is produced exclusively in the form of staple fibers (for the production of fiber-spun yarns). This means that no continuous / filament yarns are made of it.
Acrylic fibers are mainly produced as an imitation of wool fibers and the main advantage of acrylic is its thermal insulation (protection against cold).
Acrylic fiber yarns can be produced by five basic methods:
It should be noted, however, that 90% of the world production of acrylic yarns takes place in the following systems: worsted, carded and RING (classic). The production using OE and MVS systems is negligible.
The acrylic staple fibers are produced in one cutting length, e.g. 38 mm or 44. Thus, within a given production lot there are no shorter or longer fibers, and there is no need to comb the classic yarns (combing short fibers).
Acrylic fibers as a raw material for spinning are mainly produced in a count range of 0.9-15 denier, with a cutting length of 38-44 mm.
Fiber with a count range of 0.9-2.5 den is mainly used in the production of classic yarns (RING), OE and MVS.
2.5-6.0 den fibers are mainly used in worsted yarns (WORSTED).
The fibers of 6.0-15.0 den are mainly used in the carpet yarn spinning (SEMI-WORSTED).
The basic luster for acrylic fibers is bright round, which is why all yarns and acrylic fiber products have a slight luster as standard.
Classic spinning (RING)
The yarn is produced in a count range of 6 Ne = 100 tex to 40 Ne = 15 tex. These yarns are very strong (high tenacity), have a very small amount of thinning, thickening and neps (high uniformity) and the products made of them have very nice touch. The disadvantage of these yarns is the higher cost of production (higher price of yarn) and high hairiness (tendency to pilling). These types of acrylic yarns are cotton imitations but with additional thermal insulation properties.
Classic acrylic yarns (RING) are either fiber dyed and then spun straight from the colored yarn made of previously colored fiber, or in a surface system, dyeing the yarn wound on soft rolls on plastic and perforated bobbins. The most important advantage of this method is the small minimum order quantity: approx. 50-500 kg, depending on the batch of the dyeing apparatus.
The yarn is produced in a count range from 3 Nm = 330 tex to 50 Nm = 20 tex. These yarns are mainly TOW dyed or HANK dyed. TOW dyeing is much cheaper but unfortunately the minimum order quantity in color is 1500 kg and the yarn’s (product’s) touch is slightly rougher. Hank dyeing is more expensive but the minimum order quantity in color is only 350 kg and the yarn’s (product’s) touch is soft.
In worsted yarns there are two types of fluffiness:
- fluffy yarns HB (high bulk)
- RX yarns (relaxed)
The high bulk effect is created by mixing fibers of low and high shrinkage, which under the influence of temperature shrink differently, creating a spatial effect of the yarn.
Acrylic yarns can be twisted x 2 (for double yarns) or for a larger number of duplications, e.g. x 3, x 4, x 6, x 8 etc. The yarns twisted together can be knotless or with weaving knots, depending on yarn manufacturer and amount of base yarns in a twisted yarn.
All acrylic yarns can be covered with wax - they are so-called knitting yarns. These yarns have a lower spin angle which results in a pleasant touch of the yarn and products made of it.
Unlike knitting yarns, weaving yarns are not waxed and usually have a higher spin angle. This is due to the fact that for fabrics tenacity and throughput is more important than a nice product touch.
The main advantages of acrylic yarns:
ease of surface dyeing; a wide range of colors offered by yarn producers
acrylic yarns are used for the production of:
sweaters, knitted hats, scarves, knitted gloves
upholstery and decorative fabrics