This document discusses various types of antimicrobial finishes for textiles. It describes two aspects of antimicrobial protection: preventing pathogenic microbes and protecting the textile itself. Problems caused by microbial growth include functional, hygienic and aesthetic issues. The document then covers the mechanisms of antimicrobial finishes including controlled release and bound mechanisms. It provides examples of specific antimicrobial chemicals and finishes like triclosan, quaternary ammonium salts, organosilver, and chitosan. Fields of application include industrial, home, and medical textiles.

1. Antimicrobial Finishes
1. Different aspects
2. Problems and causes
3. Fibrous aspects
4. Field of Application
5. Properties of antimicrobial finish
6. Mechanisms of antimicrobial finishes
7. Control microbial growth
8. Examples

2. Two different aspects of antimicrobial
protection
• The first is pathogenic or odour causing
microorganisms (hygiene finishes).
• The second aspect is the protection of the
textile itself from damage caused by mould,
mildew or rot producing microorganisms.

3. Problems and causes
• The growth of microorganisms lead to
• functional,
• hygienic and
• aesthetic difficulties (for example staining).
• The most trouble-causing organisms are fungi
and bacteria.
• Under very moist conditions, algae can also grow
on textiles but are troublesome only because
•they act as nutrient sources for fungi and
bacteria.

4. Problems and causes
• Fungi cause multiple problems to textiles :
discoloration,
coloured stains and
fibre damage.
• Bacteria are not as damaging to fibres, but can produce
some fibre damage,
unpleasant odours – and
a slick, slimy feel.
• Often, fungi and bacteria are both present on the fabric
in a symbiotic relationship.

5. Fibrous aspects of bacterial attack
• Substances added to fibres, such as lubricants,
antistats, natural-based auxiliaries (for example
size, thickener and hand modifiers) and dirt
provide – a food source for microorganisms.
• Synthetic fibres are not totally immune to
microorganisms, for example – polyurethane
fibres and coatings can be damaged
• Wool is more likely to suffer bacterial attack than
cotton,
•Cotton is more likely than wool to be attacked by
fungi.

6. Field of Application
• Important for industrial fabrics that are
exposed to weather.
• Fabrics used for awnings, screens, tents,
tarpaulins, ropes, and the like, need
protection from rotting and mildew.
•

7. Field of Application
Home furnishings such as carpeting, shower curtains,
mattress ticking and upholstery also frequently receive
antimicrobial finishes.
• Fabrics and protective clothing used in areas where
there might be danger of infection from pathogens can
benefit from antimicrobial finishing. These include
hospitals, nursing homes, schools, hotels, and crowded
public areas.

8. Field of Application
• Textiles in museums are often treated with
antimicrobial finishes for – preservation reasons.
• Sized fabrics that are to be stored or shipped
under conditions of high temperature (~ 40 °C or
100 ºF) and humidity require an antimicrobial
finish to retard or prevent microbial growth.
• Textiles left wet between processing steps for an
extended time often also need an antimicrobial
treatment.

9. Properties of an effective antimicrobial
finish
• The growth rate of microbes can be
astoundingly rapid.
• The bacteria population, for example, will
double every 20 to 30 min under ideal
conditions (36–40 °C or 77– 98 °F, pH 5–9)
• At this rate, one single bacteria cell can
increase to 1 048 576 cells in just 7 hours. •
Therefore, antimicrobial finishes must be
quick acting to be effective.

10. Properties of an effective antimicrobial
finish
• To being fast acting, a number of other important criteria:
• The antimicrobial must kill or stop the growth of microbes
and must maintain this property through multiple cleaning
cycles or outdoor exposure.
• The antimicrobial must be safe for the manufacturer to
apply and the consumer to wear.
• The finish must meet strict government regulations and
have a minimal environmental impact.
• The antimicrobial finish must be easily applied at the textile
mill, should be compatible with other finishing agents, have
little if any adverse effects on other fabric properties
including wear comfort, and should be of low cost.

11. Mechanisms of antimicrobial finishes
• A variety of chemical finishes have been used.
• Two types based on the mode of attack on
microbes
• One type consists of chemicals that can be
considered to operate by a controlled-release
mechanism.
• The second type of antimicrobial finish consists of
molecules that are chemically bound to fibre
surfaces.

12. Controlled-release mechanism
• The antimicrobial is slowly released from a reservoir
either on the fabric surface or in the interior of the
fibre.
• This ‘leaching’ type of antimicrobial can be very
effective against microbes on the fibre surface or in the
surrounding environment.• However, eventually the
reservoir will be depleted and the finish will no longer
be effective.
• In addition, the antimicrobial that is released to the
environment may interfere with other desirable
microbes, such as those present in waste treatment
facilities.

13. Bound Mechanism
• Molecules that are chemically bound to fibre
surfaces
• These products can control only those
microbes that are present on the fibre surface,
not in the surrounding environment.
• ‘Bound’ antimicrobials, because of their
attachment to the fibre, can potentially – be
abraded away – or become deactivated – and
lose long term durability.

14. Biostats and Biocides
• Antimicrobial finishes that control the growth
and spread of microbes are more properly
called biostats, i.e. bacteriostats, fungistats.
• Products that actually kill microbes are
biocides, i.e. bacteriocides, fungicides.
• This distinction is important when dealing with
governmental regulations, since biocides are
strongly controlled.

15. Actual mechanisms of control
microbial growth
• The actual mechanisms by which antimicrobial
finishes control microbial growth are extremely
varied, ranging from
• preventing cell reproduction,
• Blocking of enzymes,
• reaction with the cell membrane (for example
with silver ions) to the destruction of the cell
walls
• and poisoning the cell from within.

16. Examples
• Antimicrobials for controlled release
• Many antimicrobial products that were
formerly used with textiles are now strictly
regulated because of their toxicity and
potential for environmental damage.
• Products such as – copper naphthenate, –
copper-8-quinolinate, – and numerous organo
mercury compounds fall into this category

17. Examples
• Materials that still have limited
use in specialised areas include
• Tributyl tin oxide (deleted in
many countries) and
• 3-iodo-propynyl-butyl
carbamate
• These products typically show a
very broad spectrum of activity
against bacteria and fungi, but
suffer from application and
durability problems

18. Antimicrobials for controlled release
• Some more useful products of this same general
type include
1. benzimidazol derivatives,
2. salicylanilides
3. and alkylolamide salts of undecylenic acid
(particularly effective against fungi).
• Application of these materials with resin
precondensates can improve durability to
laundering, but also deactivation by reaction
with the resin may occur.

19. Antimicrobials for controlled release
• A widely used biocide and preservation product is
formaldehyde.
• Solutions of formaldehyde in water, called formalin, were
used for disinfection and conservation,• for example, of
biological samples for display.
• Bound formaldehyde is released in small amounts from
common easy-care and durable press finishes.
• Therefore these finishes include at least until they are
washed – a small antimicrobial side effect.
• This can also be true for some quaternary compounds,• for
example wet fastness improvers and softeners.
• But for more effective requirements specific antimicrobial
finishes are necessary.

20. TRICLOSAN
• • One of the most widely used antimicrobial products
today is
• 2,4,4-trichloro-2- hydroxydiphenyl ether, known more
commonly as ‘triclosan’ (Fig. 15.1d).
• Triclosan finds extensive use in mouthwashes,
toothpastes, liquid hand soaps, deodorant products,
and the like.
• Although it is effective against most bacteria, it has
poor antifungal properties.
• Triclosan is also important as a textile finish, but since
its water solubility is very low, aqueous application
requires use of dispersing agents and binders.

21. QuaternaryAmmonium Salts
• • Quaternary ammonium salts have been
found to be effective antibacterial agents • in
cleaning products • and for disinfecting
swimming pools • and hot tubs. • However,
their high degree of water solubility limits
their use as textile finishes.

22. ORGONOSILVER
• Research into controlled-release antimicrobials
continues with• organo-silver compounds and
silver zeolites,• which are promising candidates
for textile finishes.
• Silver ions, for example, incorporated in glass
ceramic, have – a very low toxicity profile – and
excellent heat stability.
• These principles are also used for fibre
modification, an alternative to the antimicrobial
finishes with high permanence.

25. Blocking enzyme

26. FIBER MODIFICATION
• • In recent years a variety of antimicrobial modified
fibres have been developed, – including polyester, –
nylon, – polypropylene – and acrylic types.
• • An example of these fibre modifications is the
incorporation of 0.5–2 % of organic nitro compounds
(for example based on 5-nitrofurfural) before primary
wet or dry spinning.
• • Regenerated cellulosics can be modified with
carboxylic or sulfonic acid groups, – followed by
immersing in a solution of cationic antimicrobials
which are then – fixed to the cellulose by salt bonds.

27. MICRO-ENCAPSULATION
• • A novel approach to the controlled release
of antimicrobials is • micro-encapsulation. •
These capsules are incorporated either in the
fibre during – primary spinning – or in
coatings on the fabric surface.

28. Bound antimicrobials
• • Several antimicrobial finishes that function
at fibre surfaces have been commercialised.
• • One popular product is based on octa-decyl-
amino-dimethyl-trimethoxy-silyl-propyl-
ammonium chloride (Fig. 15.2a).
• • This material can be applied by either
exhaust or continuous methods.

29. • After application, a curing step is required to form a
siloxane polymer coating on the fibre surface.
• • This coating immobilises the – antimicrobial part of
the molecule (the quaternary nitrogen) – and provides
the necessary durability to laundering.
• Another bound finish has been developed with
• PHMB, poly-hexa-methylene biguanide (Fig. 15.2b).
• PHMB can also be – either pad – or exhaust applied.
• This chemical has the proper molecular structure to
bind tightly to fibre surfaces, yet still be an effective
antimicrobial.

30. • The antimicrobial effect of cationically charged
materials is thought to involve interaction of the –
Cationic molecule with anionic phospholipids in the
microbe’s cell walls.
• • This interaction is believed to increase the
permeability of the cell walls to the point of cell death.
• ·Bound antimicrobials
• • A new and novel approach to bound antimicrobials
was recently introduced.
• • Cotton reacted with methylol-5,5-dimethyldyantoin is
then treated with hypochlorite to form chloramines in
the fibre (Fig. 15.3).

31. • These chloramine sites have antibacterial activity
and can function as renewable antimicrobial
agents by continued treatment with hypochlorite
through household bleaching and washing after
reacting with bacteria (Fig. 15.4).
• Problems with using higher concentrations of
chloramines include yellowing with heat (for
example ironing) and cellulose fibre damage
especially significant strength loss, caused by oxy-
and hydrocellulose (generated by hypochlorous
acid

32. CHITOSAN
• Another novel approach is the application of
chitosan.
• This modified biopolymer is manufactured
from inexpensive natural waste.
• Chitin from crustacean shells (e.g. from crabs)
is converted to chitosan by alkaline treatment.
• Chitin is an analogue of cellulose with N-acetyl
groups instead of hydroxy groups in position 2
(Fig. 15.5).

33. CHITOSAN
• • Alkali splits most of them (75–95 %), generating free
amino groups that provide – Fungistatic – and bacterostatic
effects.• This mild antimicrobial activity may be amplified –
by methylation of the amino groups – to quaternary
trimethylammonium structures.
• • Chitosan can be applied by 1. microencapsulation 2. or by
reactive bonding to cellulose 3. and by crosslinking of
chitosan.
• • The advantages of the antimicrobial finish with chitosan
include 1. high absorbency properties, 2. moisture control,
3. promotion of wound healing, 4. non-allergenic, 5. non-
toxic 6. and biodegradable properties.