FINISHING
- FROM HANDLE TO FUNCTION
FUNCTIONAL
FINISHING IN THE TEXTILE INDUSTRY
R.
BREIER
Textilchemie
Dr. Petry GmbH, GERMANY
1.
Evolution of textile softeners
Softness
has always been an important aspect in textile finishing
and became even more important when the synthetic
detergents entered in industry and household. Due to the
removal of natural fats and waxes which had given the
fibres a natural softness and smoothness the usage of a
lubricant at the end of the finishing process became
necessary.
In
addition to that new processes came up, such as e. g. the
resin finishing, which made a handle correction absolutely
necessary, or the boom of synthetic fibres, the touch of
which should possibly be like synthetic fibres, as well as
an increased comfort consciousness in general.
In
the industry classical softeners, mostly based on fatty
acid amine condensates, have been used in all stages of
processing and up to the 80s they absolutely fulfilled the
requirements of the textile finishers (Fig. 1).
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Due
to innovations in the textile industry as well as in
the processing stages the requirements for softening
agents increased.
As
an example new standards in the yarn manufacture
have been set because of the rotor spinning
technology. Textiles produced from open-end yarns
showed a distinctly harder, more brittle handle than
ring-spun qualities. Classical softeners could not
sufficiently compensate such handle differences.
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since
the beginning of the 80s:
Þ
classical softeners were refined
by silicone and/or
polyethylene additives
(open-end-yarns, short liquor
jets)
since
the beginning of the 90s:
Þ
more and more "soft wave";
aminofunctional silicones, high
quality fatty acid amin
condensates,
first really convincing
hydrophile
products
since
the end of the 90s:
Þ
special effects have more and
more priority, often tailor-made
products for individual
customers
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Also
in the textile finishing a new problem came up
caused by the
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Fig.
1
Evolution
of softeners
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increasing
number of jet dyeing machines and overflows. In view of
the high shear forces in the short liquor technique
softeners with a low foaming tendency and a high shear
resistance are required for this purpose.
As
far as the making-up of knitgoods is concerned the usage
of extremely fast running sewing machines more and more
lead to problems with loop damages. The requirement for
better sewing properties could not be met in an optimal
manner by classical softeners.
Last
but not least the changed consumer demands lead to new
demands towards the softener finishing. The market more
and more asked for the "super soft wave". By the
way, this trend still continues today.
Therefore,
the development more and more went towards high-class,
multifunctional softeners which not only contain
emulsified fatty acid condensates but also different
silicones and waxes resp. special additives.
Such
combinations or special products not only allow for
distinctly better effects but the properties of the
softeners can be tailor-made to meet the individual
requirement profile.
Nowadays,
the optimisation of the soft handle is not the only target
which one wants to meet by the usage of modern products.
Besides softness, smoothness and volume special properties
which increase the consumers' benefit play an increasingly
important role.
Antistatic,
humidity transport, water and soil repellency, odour
impeding and antibacterial effects, skin care properties
are only a few examples for the additional benefit which
modern finishing agents can offer today.
Not
only with clothing textiles but especially with technical
textiles such special effects play an increasingly
important role nowadays.
2.
Classical fatty acid amin condensates
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The
major share of softeners for the final finishing
being available in the market today is at least
partly based on fatty acid amine condensation
products. A variation of the reaction partners and
reaction condition allow for a variation of the
ionic character and the molecular weight to a wide
extent. (Fig. 2).
By
the ionic character, the molecular structure and the
mol weight essential properties of the softener,
such as e.g. yellowing, softness, shear resistance,
can be controlled. Such fatty acid amine
condensation products had satisfied the market
requirements for many years.
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Fig. 2
Basic
possibilities for the synthesis of softeners
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3.
Multifunctional softeners
In
the 80s one started to increase the functionality of
lubricants by putting additives into the softener
formulation. (Fig. 3). Due to the market requirements
for softer and softer handle effects the silicone chemism
thereby was of great importance.
With
an intelligent formulation of fatty acid amine condensates
with selected additives not only better handle effects in
general could be achieved but also additional benefits.
The first really convincing hydrophilic softeners had been
introduced into the market. Low foaming, jet stable and
sewability improving softeners for the usage on modern
short liquor jets had been developed.
When
making a graphical demonstration of the factors being of
importance for the practice aptness and the commercial
efficiency of a textile softener, this can be visualised
through an application window (Fig. 4).
A
classical cationic softener (Fig. 4) has its
strengths in handle and exhaustion degree, on the other
hand, however, it shows weaknesses when it comes to
whiteness compatibility and hydrophily.
Compared
to this, the application window of a classical
nonionic softener (Fig. 4) shows a superior
yellowing resistance. With respect to handle and
exhaustion behaviour, however, such a product is
disadvantageous compared to cationic softeners.
By
tailor-made synthesis of the fatty acid amide basis
and by adding suitable additives into the softener
formulation the application window of a lubricant
can be considerably extended. (Fig. 4). Modern,
multifunctional softeners not only are of better
quality but also of a more universal usage.
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sewability,
smoothness
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polyethylene
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handle,
foaming
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silicone
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handle,
smoothness
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amino-functional
silicones
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handle,
volume
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silicone
- quats
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antistatic
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quats,
betaines
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Fig. 3
Additives
for the optimisation of softener properties
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Fig. 4
Application
window for softeners
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4.
Tailor-made lubricants / special effects
Besides
generally important properties of a finishing agent such
as soft handle, yellowing resistance, sewability
improvement and antistatic effect, more and more special
desire effects become the focus of customer interests.
(Fig. 5).
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A
modern final finishing shall and can give special
effects and additional benefits to the textile and
thus influence the potential buyer's decision
positively. The variety of possibilities is almost
umlimited. (Fig. 6).
As
a representative example two "mega trends"
of the last few months shall be taken from the
diversity of special effects and explained in
detail.
4.1.
Odour impeding finishing
For
quite a long time it has been known that due to
their special chemical build-up ring-shaped sugar
compounds, the so-called cyclodextrines, are in a
position to absorb active or harmful substances and
to store them. (Fig. 7).
With
cyclodextrin-based products used in the final
finishing odour impeding properties of the textile
can be achieved.
The
hydrophobic cavities of the cyclodextrinmolecules
are able to absorb and store smoke, sweat and odours
from the environment provided that the textile
surface has been adequately loaded. Once the storage
capacity is occupied, however, this does not work
any longer. (Fig. 8).
A
washing can renew the storage function, provided
that the active substance cyclodextrin has been
anchored on the fabric in a wash-permanent manner.
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Realization
of special functions /
guarantee of special properties
ß
for
the production of the textile , e.g.
-
sewability
-
antistatic
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tear resistance, etc.
ß
for
the customer as additional technical benefit, e.g.
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hydrophily Þ
sweat transport
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hydrophoby / oleophoby
Þ
water / oil repellent
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minimum-iron
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odor stop, etc.
ß
fashionable
effects, e.g.
-
wash out or peach skin
effects
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oil finish
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cool touch, etc.
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Fig. 5
Functional
finishing
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soft
handle
sewability
hydrophily
antistatic
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ß
buffer (Ökotex standard)
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prevent ozon fading (denim)
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contain odorous substances (perfume)
ß
regulate temperature by Phase Change Materials
(„outlast“)
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prevent pilling (biofinishing)
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produce surface effects
(peach skin or wash out)
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repel water / oil / dirt
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avoid creasing
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act skin caring
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stop odors
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act antibacterial
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Fig. 6 What
finishing agents should be able to do...
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Another
possibility is to store a desired active substance (e. g.
perfume or bactericide) already when manufacturing the
textile. This is then released successively when using the
textile.
This
allows for the realisation of a great variety of special
effects.
4.2.
Antibacterial finish
During
the past months this topic has also gained very much
in importance, ,although the antibacterial finish,
especially of skin-tight textiles, seems extremely
questionable.
It
is true that an antibacterial finish might make
sense for geo-textiles or sunshade clothes. On the
other hand, however, not only since the great fuss
about tributyl tin (TBT) in sportswear it is
legitime to ask if skin-tight textiles must have an
antibacterial finish. Most of the active substances
are wide band bactericides with a pathogenic effect.
Although
one understands the wish for a perfect hygiene it is
obvious that chemical substances having a germicidal
effect on the textile, can also influence the
natural flora of the human skin. It is not without
any foundation that meanwhile the German Federal
Ministry of Health warns against the carefree usage
of antibacterial products in household and textiles.
But there might be a "third way". By using
renewable resources, such as Chitosan, the
protection of human beings and textiles can be
brought into harmony with each other. Chitosan is a
biopolymer produced from Chitin showing a similar
structur as cellulose (Fig. 9). Chitosan has a
bacteria-impeding effect and is therefore suitable
for the antibacterial finishing of textiles. The
development of products which are ecologically
compatible is in the final stage at Textilchemie Dr.
Petry GmbH.
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Fig. 7
Odour
stop finishing with cyclodextrines
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Fig. 8
Odour
stop finishing with cyclodextrines
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Fig. 9 Antibacterial
finishing with chitosan
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5.
Final remarks
In
the final finishing of textiles finishing agents offer
excellent utilisation effects and often they offer an
optimal processing in the making-up. Furthermore, a great
variety of special effects as an additional benefit for
the consumer can be achieved. Antistatic, hydrophily,
soil-repellency and odour impediment are a few examples
only. Besides all endeavours for new effects, however, one
may not loose track regarding the responsibility for human
beings and environment.
