Acrylic fibres

Acrylic fibres were officially developed in 1948 by the same American producer who launched nylon. It was marketed two years later, but in the 50s this fibre was produced also in Europe by several companies and was characterised by a rapid boom which in 1975, barely 25 years after its invention, got it to equal wool world consumption. This success is closely related to the development of flat and circular knitting machines, which can produce considerable quantities of knitted fabrics.

In 1998 the world production of acrylics was 2.5 million tons (10% of the world total of synthetic fibres).

The name acrylics identifies the fibres made of pure polyacrylonitrile or of its co-polymers containing at least 85% in weight of acrylic nitrile. On the contrary the name modacrylics identifies the fibres produced from polymers containing at least 35% (but less than 85%) in weight of acrylic nitrile. The latter fibres have excellent flame-retardant properties and, through this characteristic, they integrate the polyester fibre range.

Acrylic fibres are offered as tow, staple and top. Quite economical are the spun- or producer-dyed types, which now account for a substantial share of the total production. The use of dyed fibres allows a lower processing cost (from fibre to dyed yarn) compared to the conventional cycle composed of raw yarn spinning and of hank, cone or piece dyeing, moreover it enables to obtain a superior quality in terms of appearance and properties of the yarn. Also dyeing evenness and shade uniformity among different lots are better. By mixing 2 to 4 basic colours with the raw fibre, a wide range of melange colours can be also obtained.

The end-uses which emphasize the characteristics of the acrylic fibre are:

- all knitted items: outerwear and underwear, hosiery, hand knitting yarns (advantages: high bulkiness, stitch clarity, unshrinkability, easy washability without any felting, quick drying, high comfort);

- fabrics, furnishing velvets, carpets (advantages: item's long duration, low soiling, easy

cleaning, good resilience of the pile which therefore does not get crushed);

- awnings (advantages: excellent resistance to sunlight, weathering and mildew);

- imitation furs (so-called ecological furs) and pile fabrics for clothing linings (advantages:

lightweight, softness and easy-care properties).

In 1991 microfibres were developed also in the acrylics sector with the launch in Italy and almost at the same time in Germany of staple fibres 0.8 dtex which were immediately well accepted by the spinning mills. The yarns produced have a very soft, but firm handle, a silky lustre as demanded by the knitwear market, optimal bulkiness and roundness and, therefore, a high covering power and high thermal insulation even with lightweight fabrics.