A New, Durable Antimicrobial Finish For Textiles
Table of Contents
Abstract
Introduction
In Vitro Microbiological Studies
In Vivo Organoleptic Evaluation
Application of Antimicrobial to Other Textiles
Conclusion
References
Tables I - II - III - IV - V
Abstract
The AEM 5700 Antimicrobial Agent (formerly known as the Dow Corning 5700
Antimicrobial Agent) imparts a durable, antimicrobial finish to textiles. The
finish protects the fabric against bacteria and fungi which cause
deterioration. It also inhibits the growth of odor-causing bacteria in In
Vitro tests. In Vivo organoleptic tests confirm the practicality of
this concept under actual use conditions in socks.
Introduction
The need to preserve fabrics against rotting and mildew stain, particularly in
industrial usage, has long been recognized. However, the use of biostats to
inhibit odor development resulting from biological growth on textiles exposed
to perspiration had not been considered a real need until relatively recently.
The greater use of synthetic fibers and blends in such items as shirts,
hosiery, blouses, and underwear has accelerated the need for bacteriostatic
finishes on clothing. The moisture-transport characteristics of such blends
tend to cause a greater degree of "perspiration wetness" than occurs
with fabrics of wholly natural fibers1. Additionally, there is a
growing volume of literature demonstrating the survival and growth of
microorganisms in textiles and their dissemination as a health risk2,3,4,5.
While several bacteriostatic textile finishes
already exist for personal wear, their use for this purpose has not gained
ready acceptance. Poor activity against mold and mildew, lack of wash
durability, inadequate safety data to meet current requirements, or a
combination of these factors has hampered their use. Consequently, a safe,
wash-resistant textile finish capable of inhibiting the growth of both bacteria
and fungi is required.
For several decades, alkoxysilanes have been
widely used by a variety of industries as coupling agents to bind and reinforce
substrates. E. Plueddemann6 has reviewed their use for such purposes.
M. Latlief et al. have described the bacteriostatic action of
quaternary ammonium compounds on textiles7,8,9. The latter compounds
exert their influence external to the microorganism by disruption of the
delicate cell membrane and therefore do not need to be absorbed in solution to
produce their bacterial killing. The combination of these technologies (that
is, the bonding power of "quats" on a substrate such as textiles)
should result in a durable, safe, antibacterial treatment and does so with AEM
5700 Antimicrobial Agent (3-trimethoxysilylpropyldimethyloctadecyl ammonium
chloride, now known as ĘGIS Microbe Shield or AEM 5700 Antimicrobial Agent). An
unexpected benefit to the binding of this organosilicon quaternary to a wide
variety of substrates is the increase in spectrum of both antibacterial and
fungal killing power10.
This report describes the practical utility of
Dow Corning 5700 Antimicrobial Agent (now AEM 5700 Antimicrobial Agent) on
BIOGUARD* socks as a representative textile. Laboratory studies were
conducted to measure the effectiveness of socks commercially treated with the
AEM 5700 Antimicrobial Agent against odor-causing bacteria isolated from the
foot. In-use clinicals were also conducted to measure actual reduction in foot
odor on textiles treated with the AEM 5700 Antimicrobial Agent.
In Vitro Microbiological Studies
The normal bacteria found on the skin of humans are capable of producing
characteristic foul odors, especially on the foot and in the auxillary region1,
11. In order to obtain a sampling of normal bacteria on the foot,
untreated 75 percent ORLON**/25 percent nylon socks were worn by
laboratory personnel during a routine workday, removed at home, sealed in
plastic bags, and returned to the microbiology lab the following day. The
bacteria were extracted from the socks in a liquid growth medium, isolated, and
identified. The bacterial isolates obtained in the study are listed in Table I.
The bacteria represent a spectrum of Gram
negative organisms capable of producing odors on textiles in contact with the
skin. Figure 1 shows the correlation of increase in odor with increase in
bacterial isolates.
Once the odor-causing bacteria were isolated,
it was necessary to determine if treatment with the AEM 5700 Antimicrobial
Agent would inhibit the growth of these microorganisms on the socks. ORLON/nlon
socks treated with AEM 5700 Antimicrobial Agent were supplied by Burlington
Socks/Adler*. The socks were tested against each of the bacterial
isolates from the foot according to AATCC Test Method 100-197712
modified to onclude 0.1 percent trition X-100 in a saline inoculom. The results
of this testing are presented in Table
II.
The socks treated with AEM 5700 Antimicrobial
Agent were effective in inhibiting the growth of the odor-causing bacteria on
the sock.
A biostatic finish on a textile such as a sock
must be durable to repeated home laundering if the benefit of the treatment is
to be realized for the life of the article. Table III shows the antimicrobial
activity of BIOGUARD socks following repeated laundering.
The antimicrobial activity of the treated
socks was not reduced after 40 laundering cycles. Treated socks were machine
washed through ten cycles in various laundry detergents used in the home.
Residual antimicrobial activity was measured. The wash durability results using
different detergents are presented in Table IV.
The antimicrobial finish applied to the socks
was durable for ten laundering cycles in all of the detergents tested.
The in vitrotests indicated that socks
treated with AEM 5700 Antimicrobial Agent do have a durable antimicrobial
finish. To study the practicality of inhibiting the growth of odor-causing
bacteria on socks under actual use conditions, an in vivoorganoleptic
test was completed.
In Vivo Organoleptic Evaluation
Burlington Socks/Adler supplied untreated ORLON/nylon control socks and socks
treated with AEM 5700 Antimicrobial Agent to an independent test laboratory*
to compare the odors of socks following normal wear by male panelists. The
socks included unwashed and washed (ten laundry cycles) control and treated
socks.
The male panelists were each given a control
and treated sock daily during the test period. Each sock was to be worn on a
specific foot. At the end of a workday, panelists reported to the lab to remove
the socks, seal them in plastic bags, and receive socks for the next day. Odor
evaluations were made by four odor judges 14 hours after removal of the socks
on each test day. Individual scoring sheets were used by the judges and new sheets
were used every day of the evaluation. The odor grading scale was 0 to 10
("no odor" to "very intense and disagreeable odor").
Two-day average odor scores were used to
compare unwashed treated and control socks to washed treated and control socks.
The Wilcoxon matched pairs test indicated that there was no difference in odor
scores between the unwashed treated and control socks at the 95 percent
confidence level.
There was a significant reduction in odor of
washed treated socks compared to washed control socks at the 99 percent
significance level. The difference in results between washed and unwashed
treated socks when compared to controls is explained by the presence of
nonsubstantive process chemicals such as dye carriers, softeners and wetting agents
which are removed upon washing. The presence of these chemicals may:
- Impart
a hydrophobic character to the socks which inhibits intimate contact of
microorganisms with the textile surface, thus reducing effectiveness.
- Impart
a pleasant, new-clothing odor which can mask unpleasant odors and is
similar in action to a deodorant.
- Impart
a temporary, leachable antimicrobial activity, usually due to the
quaternary nature of most textile finishes such as softeners and
antistats.
The results of this comparative evaluation
show that AEM 5700 Antimicrobial Agent is bonded to the textile (sock) and is
not removed by repeated laundering. In contrast to untreated controls, repeated
washing does not destroy the antimicrobial activity nor ordor reduction of the treated
socks.
Application of Antimicrobial Agent on Other Textiles
Microbiological evaluations have been completed on a variety of other textiles
treated with AEM 5700 Antimicrobial Agent such as those listed in Table V.
The fabrics include a diverse spectrum of
fiber types and blends. They were treated against a broad spectrum of
microorganisms including odor-causing bacteria, and bacteria and fungi which
cause rot and mildew. In all cases, the treated textiles exhibited inhibition
of growth of the microorganisms on the fabric, thus preventing rot and mildew,
and reducing the production of foul odors.
Conclusion
Chemical bonding of an organosilicon quaternary ammonium compound to textile
substrates results in effective reduction of odor-causing microorganisms under
actual in-use conditions of wear. Effectiveness is not reduced by laundering.
References
1).Radford,
P.J., American Dyestuff Reporter, November, 1973, p. 48-59.
2).Anderson, K.F., and Sheppard, R.W., Lancet, Vol. 1, 1959, p.
514-515. 3).McNeil, E., and Greenstein, M.,Chemical Specialties
Manufacturing Association Proceedings, 1961, p. 134-141. 4).McNeil, E., Developments
in Industrial Microbiology, Vol. 5, 1964, p. 30-35. 5).Wiksell, J.C.,
Pickett, M.S., and Hartman, P.A., Applied Microbiology, Vol. 25, 1973,
p. 431-435. 6).Plueddemann, E.P., Journal of Adhesion Vol. 2, 1970, p.
184-201. 7).Latlief, M.A., Goldsmith, M.T., Friedl, J.L., and Stuart, L.S., Journal
of Pediatrics, Vol. 39, 1951, p. 730-737. 8).Latlief, M.A., Goldsmith,
M.T., Friedl, J.L., and Stuart, L.S., Journal of Pediatrics, Vol. 40,
1952, p. 324-329. 9).Latlief, M.A., Goldsmith, M.T., Friedl, J.L., and Stuart,
L.S., Journal of Pediatrics, Vol. 40, 1952, p. 599-605. 10).Isquith,
A.J., Abbott, E.A., and Walters, P.A., Applied Microbiology, Vol. 24,
1972, p. 859-863. 11).Tachibana, D.K., Annual reviews of Microbiology,
Vol. 30, 1976, p. 351-375. 12).Technical Manual of The American Association
of Textile Chemists and Colorists, Vol. 53, 1977.
Tables
|
Table
I: |
||
|
Lab
Identification Number |
Gram Strain |
Identification |
|
I |
Positive |
Micrococcus sp. |
|
II |
Positive |
Staph epidermidis |
|
III |
Negative |
Enterobacter
aglomerans |
|
IV |
Negaitive |
Acinetobacter
calcoaceticus |
|
V |
Negative |
Enterobacter aglomerans
|
|
VI |
Positive |
Micrococcus sp. |
|
VII |
Positive |
Micrococcus sp. |
|
VIII |
Positive |
Staph aureus
(pigmented) |
|
IX |
Positive |
Staph aureus
(nonpigmented) |
|
Table
II: |
||
|
Lab
Identification Number |
Organism |
% Bacterial
Reduction |
|
I |
Micrococcus sp. |
99 |
|
II |
Staph epidermidis |
96 |
|
III |
Enterobacter
aglomerans |
90 |
|
IV |
Acinetobacter
calcoaceticus |
99 |
|
V |
Enterobacter
aglomerans |
69 |
|
VI |
Micrococcus sp. |
100 |
|
VII |
Micrococcus sp. |
99 |
|
VIII |
Staph aureus
(pigmented) |
99 |
|
IX |
Staph aureus
(nonpigmented) |
99 |
Percent bacterial reduction as measured against an
untreated control sock.
|
Table
III: |
|
|
Number of
Wash Cycles |
% Bacterial
reduction |
|
0 |
97.9 |
|
1 |
98.5 |
|
20 |
99.7 |
|
34 |
90.4 |
|
40 |
98.1 |
Percent bacterial reduction as measured against an
untreated control sock.
|
Table
IV: |
|
|
Detergent |
% Bacterial
reduction |
|
Water Only |
99.6 |
|
Tide |
99.2 |
|
Arm and Hammer |
98.9 |
|
Dynamo |
98.6 |
|
Cheer |
99.2 |
Percent bacterial reduction as measured against an
untreated control sock.
|
Table
V: |
|
Cotton/Polyester
Sheeting |
|
Carpeting and Throw
Rugs |
|
Outerwear Fabrics |
|
Underwear |
|
Nylon Hosiery |
|
Nonwoven Fabrics |
|
Mattress Ticking |
|
Filter Fabrics |