undergoes a further transformation of a different kind. Collisions
between particles of matter increase and the initial gaseous state,
comprising neutral molecules or atoms, develops into an ionised
state with an equal density of positive ions and negative electrons.
This mix of charged particles is called plasma and it is commonly
found in nature.
Interest in plasmas is not new. They have been used in neon lighting,
microelectronic etching, research into thermonuclear fusion and
in many surface treatment processes, in particular in the metal
and polymer sector. Research laboratories in the textile industry
have also been experimenting with plasma processing in a range of
Just the surface
"Unlike liquid processes which penetrate deep into the fibres,
plasma produces no more than a surface reaction, the properties
it gives the material being limited to a surface layer of around
100 angströms," (1) explains Roshan
Shishoo, Director of the Institute of Fibre and Polymer Technology
Research in Mölndal (Sweden) and coordinator of the European
These properties are very varied and can be applied to both natural
fibres and polymers, as well as to non?woven fabrics, without having
any effect on their internal structures. For example, plasma processing
makes it possible to impart hydrophilic or hydrophobic properties
to the surface of a textile, or reduce its flammability. And while
it is difficult to dye synthetic fabrics, the use of reactive polar
functions results in improved pigment fixation. Finally, with plasma
containing fluorine, which is mainly used to treat textiles for
medical use, it is possible to optimise biocompatability and haemocompatability
- essential for medical implants containing textiles.
The challenge of the vacuum
Moreover, plasma technologies are based on physical processes with
much greater advantages - especially in environmental terms - than
traditional chemical processes used in the textile industry, which
use up a great deal of water and energy and involve high waste?processing
costs. This is because "dry" processing using plasma technology
has a much higher process speed (just a few minutes, or even seconds).
"Despite all these benefits, plasma processing has failed
to make an impact in the textile sector because of a particular
constraint which is incompatible with industrial mass production",
continues Roshan Shishoo. "All the technologies developed to
date are based on the properties of low?pressure plasmas. The process
must take place in an expensive, closed?parameter vacuum system
and cannot be used for production lines operating at room temperature,
with machines processing fabric two metres wide at high speed".
Three prototypes in the service of industry
This is the challenge that a new generation of APPS (Atmospheric
Pressure Plasma Processing Systems) developed by Plasma Ireland
wishes to overcome. For the first time, this company has developed
a technology offering a comparable performance at ambient pressure
to that of "glow discharge" plasmas requiring a partial
vacuum. Plasma Ireland has provided three prototypes that can be
used to study the industrial feasibility of APPS technology and
examine at full scale the results obtained in light of the physical
properties of different types of plasma, as well as the way the
plasmas interact with various materials.
The first of these prototypes, installed at the IFP, has been made
available to the Swedish companies Almedhals (specialising in the
adhesion of polymer coatings), Borgstena Textile Sweden (automobile
textiles) and SCA Hygiene Paper. The second is in Germany, at Kirchhoff,
a company which works with wool fibres and is interested in using
the plasma technologies as a possible way of eliminating felting.
This same equipment will be made available at a later date to Polisilk
of Spain, a suitcase manufacturer which wants to improve the binding
properties of polypropylene?based coatings. The third prototypes
is being tested by the British group Scapa, which specialises in
products for the printing and textile industries.
"Europe should soon have an innovative and competitive tool
which we intend to make available internationally," believes
Tony Herbert, project manager at Plasma Ireland. "There are
only two or three other systems using plasma at atmospheric pressure
currently at the development stage - in Japan and the United States
- but no wide?ranging application for the textile sector is available
yet. So the prospects are extremely promising".
(1) 1 angström = one
ten thousandth of a micron