Polypropylene fibres belong to the polyolefin fibre group. They were the result of the research work and of the discovery of isotactic polypropylene by Giulio Natta who, in 1963, together with K.Ziegler, was awarded the Nobel prize for chemistry. The term "isotactic", which summarizes a concept of molecular structure) is best explained by the stamp issued in Sweden in 1988, which symbolizes the close link between the order given for the molecule aggregation - the spider, admirable architect of nature - and a spinneret which - like the spider — extrudes thin filaments from a melt of ordered macromolecules.
The world production of polypropylene fibres amounted in 1998 to over 2 million tons. Polypropylene fibres have following peculiar properties:
- very low specific weight - high tenacity
- high resistance to acids and caustic soda
- high rubbing resistance
- minimal thermal conductivity, low soiling thanks to low electrostatic charges and to water-repellency.
On the other hand, just because of this last property, polypropylene fibres are difficult to dye and therefore are supplied already dyed by the producer (dope dyed fibre) in very nice colours. Research works and studies aim in fact at developing dyeable types and finer filaments, according to the general trend.
Polypropylene is the most used fibre in baby diapers and adult pads, because the so-called coverstock does not absorb liquids, but spreads them to the underlying fluff, thus ensuring that the skin remains dry.
