As already mentioned in the introduction, the increase in world population (from 3 billions in 1960 to over 6 billions in the year 2000) and its growing needs made it necessary to integrate the production of natural fibres with those of man-made fibres ; these last expanded altogether at higher rates than natural fibres.
Moreover this fact permitted to countries lacking in natural raw materials to develop an important textile industry and to extend their application field (just think of the countless blending possibilities of natural with man-made fibres).
The exact product definition of artificial fibres (quite often referred to as ″cellulosics″) originates from the fact that they originate from a raw material which, though fibrous in nature, cannot be used directly by the textile industry and is therefore properly ″reclaimed″ through technical processes or ″expedients″.
Silk is the queen fibre that served as a model for the development of artificial silk, which took place at the turn of the 19th century thanks to the invention of Count Hilaire de Chardonnet who applied for the first patent covering a ″textile material similar to silk″. Silk was also the model for the chemist Max Fremery who, in co-operation with the engineer Johannes Urban, succeeded in 1891 in dissolving cotton's natural cellulose in cuprammonium and thus obtained a filament for electric bulbs with better performances and much longer life than the filament used until then. Later on, having realized that by stretching the filament they could obtain a much finer yarn suitable for the textile sector, they started the production of viscose.
The artificial silk by the cuprammonium process was successively produced and bore the trademark Bemberg. The raw material of the Bemberg yarn are the linters, which are filaments of pure cellulose covering the cotton seeds and which are used in the production of some rayon types.
At the same time a process was developed, by which cellulose was converted to the liquid state through a solution of diluted caustic soda. This principle was successively named ″viscose process″.
Viscose too has a natural origin as it is derived from the cellulose of trees, which are specially grown for this purpose. It takes 22 years to a tree (generally pine tree) to reach the inner structure and the maturity which are decisive for the future quality of viscose. 100 years after the discovery of viscose, its production, in particular filament yarn production, remains still rather complex and time-consuming; in fact 30 days are necessary to obtain viscose from the cellulose sheet.
With the advent and development of synthetic fibres, the production curve of the artificial fibres have gradually levelled out, so that already in 1970 they were surpassed by synthetics. In fact in 1970 3.6 million tons of artificial fibres were produced, compared to 4.8 of synthetics. In 1998 the output of artificial fibres amounted to 2.8 million tons against 25 million tons of synthetics; therefore artificial fibres account today for less than
10% of the total production of man-made fibres. The Italian production of artificial fibres in 1998 amounted to about 30,000 tons; our country does not produce viscose staple.
As a matter of fact, in the last few years there has been a certain revival of the interest in viscose, especially as a filament yarn, which application fields extended from the traditional and highly appreciated linings to apparel and furnishings. However the viscose producers proceeded cautiously in new investments to cope with the increased demand, since these plants often use old technologies and have to tackle serious environmental problems. On the other hand, as regards staple fibre, new processes have been developed. They are solvent processes : one for Tencel viscose fibre produced in the U.S.A. by an English company, and the other for Lyocell fibres produced in Austria by a process in which cellulose is dissolved in N-methyl-morpholine oxide (NMMO) and water.
Well established is the high wet module viscose fibre, known as modal fibre, which is often used in blend with other fibres. A 1.0 dtex micro-version of this type of staple has been recently introduced. On the market there are also types of flame resistant viscose staple, which can be used in blend with other fibres to provide textile items with fireproof properties. We also wish to mention the extra-bright silky acetate and triacetate yarns derived from cellulose acetate. After spinning, also acetate can be subjected to the regular textile operations, as twisting, texturing, warping and sizing.
