Note: Descriptions are shown in the official language in which they were submitted.
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Organic antimicrobial textile
Field of the invention
The present invention relates to a method of rendering a textile antimicrobial
by
treating the textile in a liquor application process with at least one amino
acid and/or at
least one amino acid derivative. The obtained textile is equipped with a high
antimicrobial performance, which is durable over multiple washing cycles.
Background of the invention
Disinfectants are extensively used in everyday life to prevent microbial
spread and
microbial infections, such as in the health care sector, the food industry,
agriculture, or
in common household products.
However, one major problem arising from the extensive use of disinfectants is
the
continuous contamination of the environment with these disinfectants. Usually,
disinfectants are provided in solution and applied directly onto contaminated
surfaces,
such as in hospitals or of laboratory equipment, or skin wounds. In case these
disinfectants are not neutralized, such as by autoclaving, or cannot be easily
neutralized, they finally accumulate in the waste water. Likewise, materials
equipped
with biocidal functionalities, such as antimicrobial plastics, coatings, or
textiles, e.g. in
the food packaging industry, wound dressings or functional wear, accumulate in
the
environment, and, furthermore, the antimicrobials used in these materials can
leach
out constantly. Such contamination may ultimately result in the emergence of
microbial strains that are resistant to commonly used antimicrobial agents.
In the prior art, several methods for preparing antimicrobial textile
materials are
known. However, these methods mostly rely on the use of synthetic
antimicrobial
agents that cannot be easily degraded in the environment. Moreover, many
antimicrobial agents known in the prior art are not approved for use as food
additives
or preservatives, and, in consequence, cannot be used in combination with food
packaging.
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Therefore, there is a need for a method for rendering a textile antimicrobial,
which
makes use of environmentally friendly chemical agents. The agents conferring
antimicrobial functionality to the textile are preferably natural, organic
compounds.
Such compounds are usually biodegradable, thereby reducing the risk of
accumulation
and contamination of the environment. The obtained antimicrobial textile
should be
well tolerated by living tissues and could be used, for example, for sensitive
applications
such as preservative packaging for food or as wound dressing. Moreover, the
production of such antimicrobial textile should be cost-efficient, in
particular in terms
of the costs for the chemical agents used.
Brief description of the invention
The present invention solves the shortcomings of the state of the art by
providing in a
1st embodiment of the invention a method for rendering a textile
antimicrobial,
comprising a main process cycle comprising the steps of:
- treating the textile in a main liquor application process such as padding
or preferably exhaustion, the liquor of the main liquor application
process comprising at least one amino acid and/or at least one amino
acid derivative,
- subjecting the treated textile to a heat treatment,
- optionally washing the heat-treated textile, and
- optionally drying the washed textile,
and the method preferably comprising a secondary process cycle being performed
after
the steps of the main process cycle and comprising the steps of:
- treating the textile using a secondary liquor application process, such
as
an exhaust or preferably a padding process, wherein the liquor of the
secondary liquor application process comprises at least one amino acid,
at least one amino acid derivative, and/or at least one antimicrobial
agent;
- subjecting the treated textile to a heat treatment,
- optionally washing the heat-treated textile, and
- optionally drying the washed textile.
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The main liquor application process in combination with the heat treatment
allows the
production of a textile with durable antimicrobial properties. While the main
liquor
application process may be a padding process or any other liquor application
process,
preferably exhaustion is used, as such process allows that the amino acid
and/or at
amino acid derivative are substantially uniformly dispersed across the cross
section of
the textile. The secondary process, which may be in particular a padding
process, can
enhance the overall antimicrobial activity of the textile. The at least one
amino acid
and/or at least one amino acid derivative of the secondary process cycle may
be
different from the at least one amino acid and/or at least one amino acid
derivative of
the main process cycle.
According to a 2nd embodiment, in the 1st embodiment, the amino acid and/or
amino
acid derivative comprised in the liquor of the main and/or secondary liquor
application
process has an isoelectric point equal to or above 7, preferably equal to or
above 8,
more preferably equal to or above 8.5, and/or has a pH-independent positive
charge.
The use of amino acids and/or amino acid derivatives with an isoelectric point
above 7
allows that the acids and/or amino acid derivatives carry a positive net
charge at any
pH value below the isoelectric point. Thus, the higher the isoelectric point,
the larger is
the range of pH values suitable for providing a positive net charge.
Alternatively or in
addition, amino acids or amino acid derivatives, such as quaternary ammonium
comprising amino acid derivatives, may have a constant positive charge, which
is pH
independent. It has been found that a positive charge of the amino acid and/or
amino
acid derivative applied to the textile enhances the overall antimicrobial
activity, in
particular against gram-positive and gram-negative bacteria. Positive charges
are
believed to adhere to the negatively charged membranes of microorganisms and
to
disrupt the membrane integrity, thereby acting biocidal.
According to a 3rd embodiment, in any one of the preceding embodiments, the at
least
one amino acid comprised in the liquor of the main and/or secondary liquor
application process is selected from the group consisting of natural amino
acid,
unnatural amino acid, non-proteinogenic amino acid, and/or wherein the at
least one
amino acid derivative is selected from the group consisting of peptide and
quaternary
ammonium comprising amino acid derivative.
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The inventors have found that common amino acids, peptides and quaternary
ammonium comprising amino acid derivatives can be adhered to a textile to
provide an
unexpectedly high antimicrobial activity to the textile. In contrast, when
they are
diluted in solution or suspension, these compounds do not act as efficient
antimicrobial
agents. Therefore, the antimicrobial activity of these compounds is
neutralized when
washed off the textile.
According to a 4th embodiment, in any one of the preceding embodiments, the
natural,
unnatural or non-proteinogenic amino acid is in L configuration, and/or
wherein the
peptide is a L-peptide.
The L-enantiomers of amino acids and peptides can be easily obtained from
cultures,
e.g. of E. coil, L. lactis or S. cerevisiae, rendering a complicated, cost-
inefficient
chemical synthesis unnecessary.
According to a 5th embodiment, in any one of the preceding embodiments, the
peptide
is a dipeptide or a polypeptide, wherein the polypeptide preferably contains 3
to 50
amino acids.
According to a 6th embodiment, in any one of the preceding embodiments, the at
least
one amino acid comprised in the liquor of the main and/or secondary liquor
application process is lysine, arginine, or histidine, preferably arginine.
The naturally occurring amino acids lysine, arginine, or histidine are
environmentally
friendly, as they can be obtained from common biological cultures. Moreover,
these
amino acids can be used as food additives or preservatives in the context of
finishing
textiles used in the food industry, as they are non-toxic to living tissues.
Arginine is one
of the preferred amino acids because it is available at comparatively low
costs.
According to a 7th embodiment, in any one of the preceding embodiments, the at
least
one amino acid derivative comprised in the liquor of the main and/or secondary
liquor
application process is a lantibiotic, preferably nisin.
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Nisin is commonly used as a food preservative, and, thus, can be also used for
the
finishing of textiles used in the food industry.
According to an 8th embodiment, in any one of the preceding embodiments, the
at least
one amino acid derivative comprised in the liquor of the main and/or secondary
liquor
application process is carnitine or betaine, preferably carnitine.
Carnitine and betaine are naturally occurring amino acid derivatives, which
comprise
quaternary ammonium groups that are positively charged in a pH-independent
manner. In particular carnitine has proven to have an adequate antimicrobial
activity
upon adherence to a textile.
According to a 9th embodiment, in any one of the preceding embodiments, at
least
arginine and carnitine are comprised in the liquor of the main and/or
secondary liquor
application process.
The combination of arginine and carnitine confers a particularly high
antimicrobial
activity to a textile, e.g. against both gram-negative and gram-positive
bacteria.
According to a loth embodiment, in any one of the preceding embodiments, the
at least
one amino acid or amino acid derivative in the liquors of all process cycles
together is
applied to the textile in an amount of at least 0.1 % by weight, preferably at
least 0.2%,
more preferably at least 0.5%, or at least 1%, at least 2%, at least 3%, or at
least 4%,
based on the weight of the textile.
According to a nth embodiment, in any one of the preceding embodiments, the at
least
one amino acid or amino acid derivative in the liquors of all process cycles
together is
applied to the textile in an amount of at most 20% by weight, preferably at
most 18%, or
at most 16%, or at most 14%, or at most 12%, or at most 10%, or at most 8%, or
at most
6% or at most 4%, most preferably, at most 12% based on the weight of the
textile.
According to a 12th embodiment, in any one of the preceding embodiments,
preparing
the liquor of the main and/or secondary liquor application process comprises
the
following steps:
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- preparing an aqueous reaction mixture comprising the at least one amino
acid
and/or amino acid derivative,
- incubating the reaction mixture for at least 10 minutes, preferably at
least 20
minutes, more preferably at least 30 minutes, even more preferably at least 40
minutes, and most preferably at least 50 minutes, wherein the temperature of
the reaction mixture during incubation is preferably at least 30 C, more
preferably at least 40 C, even more preferably at least 50 C, and most
preferably at least 60 C.
It was found that the incubation step of the amino acid and/or amino acid
derivative in
the reaction mixture, preferably at a pH below 6.5, preferably below 6.0, more
preferably below 5.5, even more preferably below 5.0, most preferably to a pH
of about
4.5, and/or preferably higher than 3.0, more preferably higher than 4.0, even
more
preferably higher than 5.0, most preferably about 5.5 allows a further
increase in
antimicrobial activity of the finished textile.
According to a 13th embodiment, in any one of the preceding embodiments, the
liquor
of the main and/or secondary liquor application process comprises glucosamine
and/or
polyglucosamine.
The combination of polyglucosamine (chitosan) and one or more amino acids
and/or
amino acid derivatives allows for a synergistic increase in antimicrobial
performance of
the treated textile.
Preferably, polyglucosamine is non-animal derived. For example, non-animal
derived
polyglucosamine can be isolated from fungi, such as mucorales.
Preferably at most 0.8%, more preferably at most cm% of the amine groups of
polyglucosamine are functionalized with the at least one amino acid, and/or
amino acid
derivative.
It was found that a complicated coupling of the amino acids or amino acid
derivatives
to polyglucosamine in terms of a peptide bond between the carboxy groups of
the
amino acids or amino acid derivatives and the amine groups of polyglucosamine
is not
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required to achieve a high antimicrobial activity. Rather, the compounds may
be simply
combined in the liquor or in a reaction mixture without performing a
crosslinking or
condensation reaction. Further, it was found that an ester bond between the
hydroxy
groups of chitosan and carboxy groups of the amino acids and or amino acid
derivates
can be formed in an acidic solution, which allows that the amine groups of
polyglucosamine, the amine groups of the amino acids and/or amino acid and
potential
further functional groups are non-functionalized and can carry positive
charges, e.g. in
a solution of neutral pH.
According to a 14th embodiment, in any one of the preceding embodiments, the
polyglucosamine and/or glucosamine is in a water-soluble form.
A water-soluble form of polyglucosamine can be provided by dissolving a powder
or
flakes comprising polyglucosamine in an acidic medium. By using a water-
soluble form
in the liquor, polyglucosamine can be well dispersed throughout the cross-
section of
the textile.
According to a 15th embodiment, in the 14th embodiment, polyglucosamine and/or
glucosamine is provided as a concentrated solution or suspension of at most
50%
polyglucosamine and/or glucosamine, preferably at most 40%, more preferably at
most
30%, most preferably at most 20%, and/or of at least 1%, preferably at least
5%, more
preferably at least io%, and most preferably at least 15%.
According to a 16th embodiment, in the 15th embodiment, the pH of the
concentrated
solution or suspension is adjusted to a pH below 6.5, preferably below 6.0,
more
preferably below 5.5, even more preferably below 5.0, most preferably to a
about 4.5
and/or preferably higher than 3.0, more preferably higher than 4.0, even more
preferably higher than 5.0, most preferably about 5.5.
According to a 17th embodiment, in the 16h embodiment, the pH of the
concentrated
solution or suspension is adjusted by using an organic acid, more preferably a
monocarboxylic acid, even more preferably acetic acid, lactic acid, formic
acid,
propionic acid, p-toluenesulfonic acid or a combination thereof.
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According to a 18th embodiment, in any one of the preceding embodiments 13 to
17, the
glucosamine and/or polyglucosamine in the liquors of all process cycles
together is
applied to the textile in an amount of at least o.i%, preferably at least
0.2%, more
preferably at least 0.3%, or at least 0.7% or at least 1%, based on the weight
of the
textile.
According to a 19th embodiment, in any one of the preceding embodiments 13 to
18, the
glucosamine and/or polyglucosamine in the liquors of all process cycles
together is
applied to the textile in an amount of at most 5% by weight, preferably at
most 4% by
weight, more preferably at most 3% by weight, even more preferably at most 2%,
and
most preferably at most 1.6% or at most 1%, based on the weight of the textile
material.
According to a 20th embodiment, in any one of the preceding embodiments,
preparing
the liquor of the main and/or secondary liquor application process comprises
the
following steps:
- providing the at least one amino acid and/or amino acid derivative in
powder or liquid form,
- providing the glucosamine and/or polyglucosamine in powder or liquid
form,
- preparing a preferably aqueous reaction mixture comprising
the at least one amino acid and/or amino acid derivative,
and glucosamine and/or polyglucosamine, and
- incubating the reaction mixture for at least 10 minutes, preferably at
least 20 minutes, more preferably at least 30 minutes, even more
preferably at least 40 minutes, and most preferably at least 50 minutes,
wherein the temperature of the reaction mixture during incubation is
preferably at least 30 C, more preferably at least 40 C, even more
preferably at least 50 C, and most preferably at least 60 C.
The preparation of the reaction mixture of polyglucosamine and the amino acid
and/or
amino acid derivate and the incubation step allows for a further increase in
antimicrobial activity. The inventors believe that in the reaction mixture,
polyglucosamine molecules react with the amino acid and/or amino acid
derivate, such
that an ester bond is formed. This new product can further react with the
textile during
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the liquor application process, for example via free hydroxyl groups of
polyglucosamine
molecules. A temperature of the reaction mixture of at least 30 C, more
preferably at
least 40 C, even more preferably at least 50 C, and most preferably at least
60 C was
found to foster the reaction in the incubation step.
According to a 21st embodiment, in the preceding embodiments 12 or 20, the
temperature of the reaction mixture during incubation is at most 95 C,
preferably at
most 90 C, more preferably at most 85 C, even more preferably at most 80 C,
and
most preferably at most 75 C.
According to a 22nd embodiment, in the 12th, 20th or 21st embodiment, the
reaction
mixture is stirred during the incubation step, preferably at a rotation speed
of at least
rpm.
According to a 23rd embodiment, in any one of the preceding 12th or 20th to
22nd
embodiments, the pH of the reaction mixture is below 6.5, preferably below
6.0, more
preferably below 5.5, even more preferably below 5.0, most preferably about
4.5 and/or
preferably higher than 3.0, more preferably higher than 4.0, even more
preferably
higher than 5.0, most preferably about 5.5.
An acidic pH improves the solubility of polyglucosamine in the concentrated
solution
and/or aqueous reaction mixture.
According to a 24th embodiment, in the preceding embodiment, the pH is
adjusted by
using an organic acid, more preferably a monocarboxylic acid, even more
preferably
acetic acid, lactic acid, formic acid, propionic acid, p-toluenesulfonic acid
or a
combination thereof.
These acids have proven compatible with the overall textile finishing as
explained in
further detail below.
According to a 25th embodiment, in any one of the preceding embodiments, in
the main
and/or secondary liquor application process, at least 5o%, preferably at 70%,
more
preferably at least 80%, even more preferably at least 90%, and most
preferably at least
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95% of the at least one amino acid, amino acid derivative and/or
polyglucosamine
bound to the textile are not bound to cellulose molecules dispersed or
dissolved in the
liquor.
According to a 26th embodiment, in any one of the preceding embodiments, the
liquor
of the main and/or secondary process cycle comprises one, two, three, or all
four of the
antimicrobial agents selected from the group consisting of azole based
compound,
silver ions, polyhexamethylene biguanide, quaternary ammonium organosilane.
These antimicrobial agents are not biodegradable. In certain applications it
may
nevertheless be desirable to add them because they increase the overall
antimicrobial
activity of the textile. The inventors found that these antimicrobial agents
can be well
combined with amino acids and/or amino acid derivatives.
According to a 27th embodiment, in the preceding 26th embodiment, the azole
based
compound is propiconazole.
According to a 28th embodiment, in any one of the 26th or 27th embodiments,
the
quaternary ammonium organosilane is a hydrophilic quaternary ammonium
organosilane, preferably an organomethoxysilane compound, more preferably N-
trimethoxysilylpropyl-n,n,n-trimethylammonium chloride.
According to a 29th embodiment, in any one of the 26th to 28th embodiments,
the
quaternary ammonium organosilane compound in the liquors of all process cycles
together is applied to the textile in an amount of at least o.1% by weight,
preferably at
least 0.2% by weight, more preferably at least 0.25% by weight, and most
preferably at
least 0.3% by weight, based on the weight of the textile material.
According to a 30th embodiment, in any one of the 26th to 29th embodiments,
the
quaternary ammonium organosilane compound in the liquors of all process cycles
together is applied to the textile in an amount of at most 5% by weight,
preferably at
most 1.5% by weight, more preferably at most 1.2% by weight, in particular at
most
to% by weight, and most preferably at most 0.8% by weight, based on the weight
of the
textile material.
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According to a 31st embodiment, in any one of the 26th to 30th embodiments,
the silver
cations or silver cations trapped in an inorganic or organic matrix in the
liquors of all
process cycles together are applied to the textile in an amount of at most cm%
by
weight, preferably at most 0.05% by weight, more preferably at most 0.02% by
weight,
and most preferably at most about o.oi% by weight, based on the weight of the
textile
material.
According to a 32nd embodiment, in any one of the 26th to 31st embodiments,
the silver
cations or silver cations trapped in an inorganic or organic matrix in the
liquors of all
process cycles together are applied to the textile in an amount of at least
0.001% by
weight, preferably at least 0.002% by weight, more preferably at least 0.003%
by
weight, and most preferably at least about 0.005% by weight, based on the
weight of
the textile material.
According to a 33rd embodiment, in any one of the 26th to 32nd embodiments,
polyhexamethylene biguanide in the liquors of all process cycles together is
applied to
the textile in an amount of at most 0.5% by weight, preferably at most 0.4% by
weight,
more preferably at most 0.3% by weight, and most preferably at most 0.2% by
weight,
based on the weight of the textile material.
According to a 34th embodiment, in any one of the 26th to 33rd embodiments,
polyhexamethylene biguanide in the liquors of all process cycles together is
applied to
the textile in an amount of at least 0.03% by weight, preferably at least
0.05% by
weight, or at least o.10% by weight, preferably at least 0.15% by weight,
based on the
weight of the textile material.
According to a 35th embodiment, in any one of the 26th to 34th embodiments,
the azole-
based compound in the liquors of all process cycles together is applied to the
textile in
an amount of at most 0.6% by weight, preferably at most 0.5% by weight, more
preferably at most 0.4% by weight, and most preferably at most 0.3% by weight,
based
on the weight of the textile material.
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According to a 36th embodiment, in any one of the 26th to 35th embodiments,
the azole-
based compound in the liquors of all process cycles together is applied to the
textile in
an amount of at least 0.05% by weight, preferably at least o.io% by weight,
more
preferably at least 0.15% by weight, and most preferably at least 0.20% by
weight,
based on the weight of the textile material.
According to a 37th embodiment, in any one of the preceding embodiments, the
liquor
of the main and/or secondary liquor application process comprises water,
preferably
water and isopropanol, more preferably wherein isopropanol is contained in the
liquor
at a concentration of between 0.05 and 2 wt.%, preferably between 0.1 and 1
wt.%,
more preferably between 0.2 and 0.6 wt.%.
Isopropanol reduces the surface tension of water, thereby facilitating the
penetration of
the amino acids and/or amino acid derivatives into the fibers of the textile.
Isopropanol
evaporates during the liquor application process and/or heat treatment.
According to a 38th embodiment, in any one of the preceding embodiments, the
pH of
the liquor of the main and/or secondary liquor application process is equal to
or below
6.5, preferably equal to or below 6.0, more preferably equal to or below 5.5,
even more
preferably equal to or below 5.0, most preferably about 4.5 and/or preferably
higher
than 3.0, more preferably higher than 4.0, even more preferably higher than
5.0, most
preferably about 5.5.
An acidic pH can catalyze the reaction between the amino acids and/or amino
acid
derivatives with the textile, in particular when the reaction is an
esterification reaction.
According to a 39th embodiment, in the preceding 38th embodiment, the pH of
the
liquor of the main and/or secondary liquor application process is adjusted by
an
organic acid, preferably a monocarboxylic acid, in particular acetic acid,
lactic acid,
formic acid, propionic acid, p-Toluenesulfonic acid or a combination thereof.
Organic acids are compatible with most textile materials, such as viscose or
cotton
whereas HCI for example may impair the textile. In particular monocarboxylic
acids
can be used in the liquor application processes, as these acids do not
influence the
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overall charge of the textile after application of the amino acids and/or
amino acid
derivatives. In contrast, multifunctional acids, such as di- or tricarboxylic
acids, e.g.
citric acid, can increase the overall negative charge of the textile, in case
of binding to
the textile via one of the functional groups.
According to a 40th embodiment, in any one of the preceding embodiments, the
liquor
comprises a cross linking reagent, preferably an isocyanate cross linking
agent or an
acrylic crosslinker, more preferably a blocked isocyanate cross linking agent.
Cross linking agents are typically not biodegradable. In certain applications
it may
nevertheless be desirable to add them because they can covalently bind to the
amino
acids and/or amino acid derivatives and to functional groups of the textile,
thereby
increasing the wash-resistance of the antimicrobial properties of the obtained
textile.
According to a 41st embodiment, in any one of the preceding embodiments,
during an
exhaust process, the liquor has a temperature of at least 40 C, in particular
at least
45 C, preferably at least 50 C, more preferably at least 55 C, even more
preferably at
least 60 C, most preferably at least about 65 C.
According to a 42nd embodiment, in any one of the preceding embodiments,
during an
exhaust process, the liquor has a temperature below boiling temperature,
preferably at
most 95 C, more preferably at most 90 C, particularly at most 85 C, and
most
preferably at most about 80 C.
According to a 43rd embodiment, in any one of the preceding embodiments, the
exhaust
time of an exhaust process is at least 30 minutes, preferably at least 40
minutes, more
preferably at least 50 minutes, particularly at least 55 minutes, and most
preferably at
least about 60 minutes, and/or at most 120 minutes, in particular 90 minutes,
preferably at most 80 minutes, more preferably at most 75 minutes, even more
preferably at most 70 minutes, even more preferably at most 65 minutes, most
preferably at most about 60 minutes.
According to a 44th embodiment, in any one of the preceding embodiments, the
heat
treatment of the main and/or secondary process cycle comprises drying and/or
curing.
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According to a 45th embodiment, in the preceding 44th embodiment, drying is
conducted at an ambient temperature of at most 190 C, preferably at most 180
C,
more preferably at most 170 C, and/or at an ambient temperature of at least
60 C,
preferably at least 80 C, more preferably at least 100 C, and most
preferably at least
about 120 C.
According to a 46th embodiment, in any one of the preceding 44th or - -th
45 embodiments,
curing is conducted at least partially at an ambient temperature of at least
150 C,
preferably at least 160 C, more preferably at least 170 C, particularly at
least 175 C,
and most preferably at least about 180 C, and/or at an ambient temperature of
at most
205 C, preferably at most 195 C, more preferably at most 190 C,
particularly at most
185 C, and most preferably at most about 180 C.
The curing temperature is adapted to promote the (covalent) binding of the
amino
acids and/or amino acid derivatives to the textile.
According to a 47th embodiment, in any one of the preceding embodiments, the
starting
textile comprises hydroxyl, peptide and/or carbonyl groups, in particular
hydroxyl
and/or peptide groups.
These groups enable fixing, bonding, attaching or adhering of one or more
amino acids
and/or amino acid derivatives to the textile. In exemplary embodiments, the
starting
textile material comprises peptide and/or hydroxyl groups, in particular
hydroxyl
groups.
According to a 48th embodiment, in any one of the preceding embodiments, the
starting
textile is a cellulosic textile material, an animal-derived textile material,
a synthetic
textile material, or a blend comprising a cellulosic, animal-derived and/or a
synthetic
textile material.
According to a 49th embodiment, in the 48th embodiment, the cellulosic textile
comprises one or more selected from the group consisting of cotton, viscose,
rayon,
linen, hemp, ramie, jute, and combinations (blends) thereof. In particular,
the cellulose
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textile comprises at least 50%, preferably at least 60%, more preferably at
least 70%
viscose.
According to a 50th embodiment, in the 48th embodiment, the animal-derived
textile
comprises one or more selected from the group consisting of wool and silk.
According to a 51st embodiment, in the 48th embodiment, the synthetic textile
comprises one or more selected from the group consisting of polyester,
polyamide
(nylon), acrylic polyester, spandex (elastane, Lycra), aramids, modal, sulfar,
polylactide
(PLA),1yocell, polybutyl tetrachloride (PBT), and combinations (blends)
thereof.
According to a 52nd embodiment, in any one of the preceding 47th to 51st
embodiment,
at least 90%, preferably at least 95%, more preferably at least 98%, even more
preferably at least 99%, and most preferably about l00% of the starting
textile is made
from a renewable raw material, and/or is biodegradable and/or natural and
organic.
According to a 53rd embodiment, in any one of the preceding embodiments, the
textile
is selected from the group consisting of woven, knitted, crocheted, bonded,
warp
knitted, and non-woven fabrics, preferably wherein the antimicrobial textile
is a woven
fabric.
The preferred textiles are multifilament fabrics, i.e. fabrics made of
multifilament
yarns. Fabrics are preferred because their treatment is significantly cheaper
than the
treatment of yarns or even fibers. Fabrics made of multifilament yarns are
preferred
over fabrics made of monofilament yarns because they are stronger, have a
higher
surface area, and can be blended.
According to a 54th embodiment, the present invention further relates to an
antimicrobial textile obtainable by any one of the preceding embodiments,
preferably
wherein the at least one amino acid and/or amino acid derivative is (are)
adhered or
bound or covalently bound to the textile, and/or, if present, preferably
wherein also the
glucosamine, polyglucosamine and/or further antimicrobial agent(s) is (are)
adhered or
bound or covalently bound to the textile.
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According to a 55th embodiment, in the 54th embodiment, the amino acid, amino
acid
derivative, glucosamine, polyglucosamine and/or further antimicrobial agent
(s)
adhered or bound or covalently bound to the textile have an individual weight
as
defined for the respective antimicrobial agents in any one of embodiments 10,
11, 18,
19, 29 to 36.
According to a 56th embodiment, in the 54th or - -th
55 embodiment, the antimicrobial
textile exhibits a reduction value of P. aeruginosa ATCC 9027 and/or
Staphylococcus
aureus ATCC 6538, measured in accordance with AATCC test method 100-2012, of
at
least 99%, preferably at least 99.9%, more preferably at least 99.99%, most
preferably
at least 99.999%, within 24 hours of contact time, preferably within 6 hours
of contact
time, more preferably within 1 hour of contact time, even more preferably
within 15
minutes of contact time, particularly within 10 minutes of contact time.
According to a 57th embodiment, in the 56th embodiment, the reduction value is
achieved even after at least 5 laundry washed, more preferably, even after at
least 10
laundry washes in a laundry washing machine at 40 C for 20-40 minutes,
preferably
using brand name non-antimicrobial, non-ionic and non-chlorine containing
laundry
detergent, preferably followed by a standard rinse cycle.
According to a 58th embodiment, in any one of the 54th to 57th embodiments,
the
antimicrobial textile exhibits a zero growth of microbes when tested in
accordance with
AATCC Test Method 30-2013 Part III (Agar Nate, Aspergillus Niger or Candida
albicans).
According to a 59th embodiment, in the 58th embodiment, the zero growth value
is
achieved even after at least 5 laundry washed, more preferably, even after at
least 10
laundry washes in a laundry washing machine at 40 C for 20-40 minutes,
preferably
using brand name non-antimicrobial, non-ionic and non-chlorine containing
laundry
detergent, preferably followed by a standard rinse cycle.
According to a 60th embodiment, in any one of the 54th to 59th embodiments, at
least
90%, based on weight, preferably at least 95%, more preferably at least 98%,
even
more preferably at least 99%, particularly 99.5%, and most preferably about
l00% of all
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antimicrobial agents adhered to or comprised by the textile are biodegradable
and/or
natural and organic.
All percentages hereinafter refer to weight unless otherwise indicated. "%
owf' or "%
o.w.f." stands for "of weight fabric" and is the weight percentage of the
uptake of the
antimicrobial agent in relation to the fabric. "gpl" or "GPL" stands for
"grams per liter".
"R.t." stands for "room temperature", which is a temperature in the range of
15 to 35 C.
The term "antimicrobial" as used in the context of the present invention
relates to the
ability to kill at least some types of microorganisms, or to inhibit the
growth or
reproduction of at least some types of microorganisms. Said term relates to
any
compound, agent, product or process that is harmful to one or more
"microorganism"
as used in the context of the present invention. Preferably, the one or more
"microorganism" gets killed by the "antimicrobial" product or process.
The term "antimicrobial agent" as used herein means any chemical compound that
acts
antimicrobial against at least some types of microorganisms. Exemplary
antimicrobial
agents are chitosan, quaternary ammonium organosilane, silver cations,
polyhexamethylene biguanide (PHMB), and propiconazole. Amino acids and/or
amino
acid derivatives are not antimicrobial agents per se, but become antimicrobial
upon
adherence and/or binding to the textile. Therefore, in the context of amino
acids
and/or amino acid derivates adhered to the textile, these compounds are also
to be
understood as antimicrobial agents.
The terms "microorganism" and "microbe", which are used interchangeably in the
context of the present invention, are defined to comprise any organism too
small to be
seen by the unaided eye, such as, especially, single-celled organisms. In
particular, the
terms "microorganism" and "microbe" cover prokaryotes including bacteria and
archaea, eukaryotes including protists, animals like dust mites or spider
mites, fungi,
and plants like green algae, as well as viruses.
The term "textile" as used herein means a textile or textile material in any
form and
includes fibers, yarns, threads, ply yarns, fabrics produced from fibers
and/or yarns,
and the finished products produced from fibers, yarns, and/or fabrics. The
textile can
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be woven, knitted, crocheted, bonded and/or non-woven fabric. It can be spun,
electrospun, drawn or extruded.
The term "biodegradable" as used herein refers to any form of textile, amino
acid,
amino acid derivative, chitosan, antimicrobial agent or other chemical
compounds,
which can be decomposed by living cells, such as bacteria.
The term "natural and organic" as used herein refers to organic compounds that
may by
produced by living organisms. For example, all amino acids that are
synthesized by
biological cells or chitosan are natural and organic compounds.
Detailed description of the invention
Preferred embodiments and examples of the invention will be described in the
following detailed description. It is emphasized, however, that the present
invention is
not limited to these embodiments.
The present invention relates to a method for rendering a textile
antimicrobial.
Advantageously, the method allows the use of naturally occurring functional
agents,
such as amino acids or peptides, or a combination of these compounds with
chitosan
for the finishing of a textile.
The inventors have discovered that the deposition of positive surface charges
on a
textile, such as by (covalently) binding the amino acid arginine and/or the
amino acid
derivative carnitine to the textile, confers a high antimicrobial activity to
the textile.
While not wishing to be bound by theory, it is believed that a high density of
positive
charges of the amino acid and/or amino acid derivative disrupts the cellular
membrane
of microorganisms, e.g. of gram-negative or gram-positive bacteria.
The obtained antimicrobial textile is environmentally friendly, as the
antimicrobial
agents, such as natural amino acids, are biodegradable. Moreover, the use of
amino
acids and/or amino acid derivatives as antimicrobial agents lowers the
production costs
for the antimicrobial textile, e.g. in comparison to antimicrobial textiles
comprising
chitosan only.
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Liquor application process:
The method according to the invention comprises a liquor application process,
in
particular an exhaust process, for the application of the amino acids and/or
amino acid
derivatives. As is known in the art, during an exhaust process, a textile
material is
brought in contact with a liquor which comprises ingredients which are
transferred to
the article during the exhaust process. This can be achieved by guiding the
textile
material through a container filled with the liquor. Yarn and fabrics are
typically
treated with exhaust processes. During a common exhaust process, chemicals to
be
applied to a textile material are dissolved or dispersed in a solvent, e.g.
water, according
to the required material to liquor ratio, which describes the ratio between
the weight of
the textile to be treated and the weight of the liquor. For example, if the
desired
material to liquor ratio is 1:2, there would be 600 kg of liquor for 300 kg of
textile
material to be exhausted. Following, the textile material is brought in
contact with the
liquor, for example by immersing it into the liquor, whereby the chemicals
preferably
contact the fibers and more preferably enter the fibers. For obtaining proper
diffusion
and penetration of the chemicals in the fiber, a respective liquor temperature
and
respective exhaustion time are set, such that kinetic and thermodynamic
reactions take
place as desired. As the textile material and its fibers absorb the chemicals,
the
concentration thereof in the liquor decreases. As is known in the art, the
degree of
liquor exhaustion as a function of elapsed time is termed extent of the
exhaust process.
The percentage of the chemicals initially present in the liquor which is
exhausted onto
the textile at the end of the process is called exhaustion rate or exhaust
rate.
In an exhaust process, the textile opens up and the fibers are individually
exposed to
penetration by the amino acids and/or amino acid derivatives. This is
particularly true
for multifilament yarns or fabrics made out of them, which are preferred for
most
applications because they are stronger, have a higher surface area, and can be
blended.
Thus, by use of an exhaust process, the agents can diffuse into the fibers and
do not
occupy the surface space of the fibers to the same extent as it is the case in
more
superficial liquor application processes like padding or spraying. Therefore,
the use of
an exhaustion process in the main process cycle allows to improve the
antimicrobial
performance by a secondary antimicrobial process cycle, in particular by a
secondary
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process cycle in which a padding process is used, or to apply other functional
agents to
the textile in a further process cycle. In contrast, repeated superficial
liquor
applications like repeated padding applications will not improve performance,
or at
least not improve performance to the same extent. Furthermore, the inventors
found
that leaching is at lowest values only when exhaustion is used in the main
process cycle.
On the other hand, in the case of non-woven fabrics, exhaustion may not be
preferred
because non-woven fabrics can oftentimes not withstand the forces applied by
exhaustion machines like jiggers.
Exhaustion may be performed by any suitable technique, and on any suitable
machine,
like a yarn dying machine, a beam machine, a winch machine, a jet-dyeing
machine, a
continuous dyeing range (CDR), continuous bleaching range (CBR), or a jigger
machine.
The exhaustion allows for evenly spreading the liquor across the entire cross
section of
the textile material, such that preferably no spot of the textile material is
left untouched
by the liquor. As a result, interactions and/or bonds may be created between
the textile
material and one or more amino acids and/or amino acid derivatives at this
time.
Preferably most of the agents of the liquor are exhausted evenly onto the
entire cross
section of the textile material. Preferably, an exhaustion rate of the exhaust
process is at
least 75%, more preferably at least 85%, more preferably at least 90%, and
most
preferably at least 95%, such that the textile material picks up most
preferably about
95% of the amino acids, amino acid derivatives or antimicrobial agents
contained in the
exhaust liquor. This exhaustion rate allows for reducing costs, as most of the
ingredients of the liquor are exhausted by the textile material. It is also
more ecological
than processes with lower pickup rates.
In general, more heat on the fabric is better for bonding. Therefore,
preferably, the
temperature of the liquor during the exhaust process is sufficiently high and
the
exhaust time is sufficiently long such that the one or more antimicrobial
agents in the
liquor are substantially uniformly dispersed across the cross section of the
textile
material as a result of the exhaust process. Thus, the temperature of the
liquor should
be sufficiently high and the exhaust time should be sufficiently long such
that
preferably the textile material is well impregnated and the antimicrobial
agents are
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dispersed throughout the entire textile material. Preferably, the exhaust time
is
sufficiently long and the temperature of the liquor during the exhaust process
is
sufficiently high such that the textile material can achieve the desired
antimicrobial
performance after a respective curing process, as will be outlined below.
However, too much heat causes yellowness and weakens the fabric. Therefore,
preferably, the temperature of the liquor during the exhaust process is
sufficiently low
and/or the exhaust time is sufficiently short such that the textile material
does not
discolor and/or turn yellow and/or its breaking (tensile) strength is not
reduced by
more than 15%, preferably not more than 10%, more preferably not more than 7%,
and
most preferably not more than 5%, as a result of the exhaust process. As is
known in the
art, excessive heat leads to yellowing of the textile material, which may be
undesirable.
Accordingly, the temperature of the liquor should not be too high. At too high
temperatures, too much steam forms, reducing the efficiency of the process.
Furthermore, if the temperature of the liquor is too high, turbulences can
occur within
the liquor bath and the textile material may get harmed. Further, with
increasing
exhaust time, the textile material may become weaker, i.e. its breaking
strength may
decrease.
The term exhaust time when used in the context of the present invention is
preferably
defined as the period starting when at least part of the entire batch of
textile material
first comes into contact with the liquor and lasting until the last part of
the batch is
taken out of the liquor. For a given application, the ideal exhaust time can
vary
significantly. In case the textile is a fabric, it will depend on the type of
machine, the
size of the liquor bath, and the length and weight of the fabric. For example,
if the ideal
exhaust time for a fabric of a length of 1,500 meters is 60 minutes, the ideal
exhaust
time for a fabric of a length of 3,000 meters may be 100 minutes under
otherwise
identical conditions. Whenever an exhaust time is specified herein, it refers
to the time
which is equivalent to the exhaust time of a fabric of 1,500 meters in length
and 200
g/m2 in weight on a standard jigger machine (e.g. model number Ynoo
manufactured
by Yamuda) being operated at a standard fabric speed (e.g. 50 meters/minute).
For any
given textile material and exhaustion machine, the skilled person, using
common
general knowledge, will be able to determine the exhaust time which is
equivalent to an
exhaust time specified for the above-mentioned parameters.
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Accordingly, with the exhaust process, one or more amino acids and/or amino
acid
derivatives, and preferably antimicrobial agents are substantially uniformly
dispersed
across the cross section of the textile material.
The exhaust process is followed by a heat treatment. In the case that there is
only one
process cycle, the heat treatment may comprise drying and curing. Curing,
which takes
place at high temperatures, preferably 180 C, is necessary to fully bind the
amino acids
and/or amino acid derivatives to the textile material in a non-leaching or
substantially
non-leaching manner. Prior to curing, the textile must be dried because the
temperature of the textile cannot exceed 100 C until the water in the textile
is
evaporated. In the case that the main process cycle is followed by further
process cycles,
be it a secondary process cycle as described herein below, or a process cycle
which
imparts other properties like hydrophilicity or hydrophobicity to the textile,
there is
preferably no curing at this stage, i.e. in the main process cycle. This is
for economic
reasons, but also because curing may close up or seal the textile so that
treatments in
further process cycles become less effective. In the case of a further process
cycle, the
textile should be dried because otherwise it would not absorb the liquor of
the further
process cycle. Drying could be performed by low temperatures such as room
temperature. However, to speed up the manufacturing process, drying it is
preferably
performed by a heat treatment. Also, the heat treatment can achieve basic
bonding of
the agents to the textile so that they are not washed out in a subsequent
washing step.
The drying can be performed by using normal heat setting processes, depending
on the
actually used textile material. Preferably, the drying of the textile material
is conducted
at least partially at a temperature of at least 60 C, more preferably at
least 100 C, even
more preferably at least 110 C, and most preferably at least about 120 C.
Lower
temperatures would require longer dwell time, which is disadvantageous because
a
longer dwell time has a negative impact on the textile in terms of yellowing
and also
strength of the fabric.
Preferably, the drying of the textile material is conducted at a temperature
of at most
190 C, more preferably at most 180 C, particularly at most 170 C. Even more
preferably, the drying of the textile material is conducted at a temperature
of at most
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150 C, more preferably at most 140 C, particularly at most 130 C, and most
preferably
at most about 120 C.
Preferably, the drying time at the temperatures given above is of at least 30
seconds,
preferably at least 40 seconds, more preferably at least 50 seconds, and most
preferably
at least about 60 seconds, per loo g of fabric weight per m2 (in case the
textile material
is a fabric). Further preferably, the drying is performed over a period of at
most 120
seconds, preferably at most 90 seconds, more preferably at most 75 seconds,
most
preferably at most about 60 seconds, per loo g of fabric weight per M2 (in
case the
textile material is a fabric). It will be appreciated that the drying times
increase with
increasing fabric weight (per m2). The skilled person understands that similar
drying
times apply if the textile material is a yarn, and understands to choose
respective drying
times which then depend on the yarn diameter.
The drying process can be typically conducted by passing the textile material
through a
stenter or stenter frame (sometimes also referred to as a "tenter") or similar
drying
machine. By drying the textile material, preferably excess moisture is
removed.
The drying process may be followed by a curing process if there are no further
process
cycles. In this case, the curing process can be as described below. However,
while in the
secondary process cycle the curing process is preferably carried out together
with
drying process in one single pass through the stenter, there are preferably
two separate
passes through the stenter for drying and curing in case there is only one
process cycle.
This is because if there is only one process cycle, the textile is typically
wetter, and
therefore the drying process can be better controlled if it is performed in a
separate
pass through the stenter.
On the other hand, if there is a further liquor application process cycle,
drying may be
followed by a washing step. During washing, the textile material is preferably
washed in
water, further preferably without using detergents. Preferably, the textile
material is
washed in a bath, such as e.g. a water bath, having a temperature between 30
C and 50
C, further preferably between 35 C and 45 C. The washing time is preferably
at least
35 minutes and more preferably at least 40 minutes.
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After the main process cycle, the resulting textile material already features
antimicrobial properties. However, they can be further improved by conducting
an
optional secondary process cycle, such as padding. Other liquor application
processes
can be used in the alternative, such as e.g. an exhaust process, coating
process or
spraying process. However, a padding process has proven to be particularly
advantageous because it is less time consuming and therefore less expensive
than
exhaustion, it provides for a more even distribution of the liquor than
spraying (and
unlike spraying can be applied on both sides of a fabric at the same time),
and it yields
better results in terms of non-leaching properties than coating because a
coating paste
typically contains ingredients which tend to leak.
Any suitable technique can be utilized for performing padding, in which
preferably a
respective liquor (which may or may not be the same liquor as the one of
exhaust
process ii and will be detailed further below) is prepared and fed through a
pump to a
respective padding mangle. Accordingly, padding process 15 preferably
comprises
applications of one or more rolls to obtain optimum wet pickup of the liquor
on the
textile material. The appropriate padding mangle pressure is typically
predetermined,
depending on the quality of the textile material, and it is in general set
such that the wet
pickup of the antimicrobial agents is optimized. The liquor may be at room
temperature
or it may be heated during the padding process.
Preferably, the padding process is performed in a padding mangle at a pressure
of 0.5
to 4 bars, more preferably 1.0 to 3.0 bars, even more preferably 1.5 to 2.5
bars, most
preferably about 2 bars. The pick-up rate (or "wet pick-up") specifies the
amount of
liquor applied and is defined as a percentage on the weight of the dry
untreated textile
as follows:% pick-up rate = weight of liquor applied x loo / weight of dry
textile. For
example, a pick-up rate of 65% means that 65o grams of liquor are applied to 1
kg of
textile. The pick-up rate of the padding process according to the invention is
preferably
at least 40%, more preferably at least 5o%, even more preferably at least 55,
particularly at least 60%, and most preferably at least about 65%. It is
preferably at
most 90%, more preferably at most 80%, even more preferably at most 75%,
particularly at most 70%, and most preferably at most about 65%.
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After padding, a heat treatment comprising drying and curing may be performed.
Curing may be defined as heat treatment, at temperatures as mentioned in the
present
application, of the textile material in the dry state, wherein dry means that
the textile is
99% devoid of moisture. Typically, a stenter may be used for the curing.
Curing is preferably conducted at least partially at a curing temperature of
at least 150
C, preferably at least 160 C, more preferably at least 170 C, even more
preferably at
least 175 C, and most preferably at least about 180 C. Preferably, curing is
conducted
at a temperature of at most 205 C, preferably at most 195 C, more preferably
at most
190 C, even more preferably at most 185 C, and most preferably at most about
180 C.
Thus, the preferred curing temperature is about 180 C.
Preferably, curing is performed at the temperature discussed above over a
period of at
least 20 seconds, preferably at least 24 seconds, more preferably at least 28
seconds,
and most preferably at least about 30 seconds per 100 g of the fabric weight
per M2 (in
case the textile material is a fabric). Preferably, the time period during
which this
temperature is applied is at most 50 seconds, preferably at most 45 seconds,
more
preferably at most 40 seconds, even more preferably at most 35 seconds, and
most
preferably at most about 30 seconds per 100 g of fabric weight per M2 (in case
the
textile material is a fabric). Thus, in the most preferred embodiment, a
curing
temperature of about 180 C is applied for about 30 seconds per 100 g of
fabric weight
per M2. However, in case of heavy fabrics, the preferred curing time is
longer, namely
45 seconds at the temperature discussed above for fabrics of 350 to 500 g/m2,
and 60
seconds for fabrics of more than 500 g/m2. This is because with increasing
thickness of
the fabric, heat waves will take more time to get to the core of the fabric.
It will be
appreciated that modified temperatures are applied in case that the textile
material is a
yarn, and the dwell times and curing temperatures then depend on the yarn
diameter.
Since the curing temperature is substantially independent from the textile
material,
only the curing time (and drying time) have to be adjusted when using
different textile
materials. The inventors found that the curing time, or dwell time, increases
about
linearly with increasing weight of the textile material.
Preferably, curing immediately follows drying. Thus, the textile material
preferably
does not substantially cool down between the drying and the curing.
Accordingly, when
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performing the drying and curing directly one after the other, both steps are
preferably
performed over a total period of at least 45 seconds, preferably at least 50
seconds,
more preferably at least 55 seconds, and most preferably at least about 60
seconds per
loo g of fabric weight per M2 (in case the textile material is a fabric).
Further preferred,
the drying and curing are performed over a total period of at most 75 seconds,
preferably at most 70 seconds, more preferably at most 65 seconds, and most
preferably at most about 60 seconds per loo g of fabric weight per M2 (in case
the
textile material is a fabric).
Functional agents:
The liquor of the main liquor application cycle, and optionally the liquor of
the
secondary process cycle comprises at least one amino acid and/or at least one
amino
acid derivative.
Both the amino acid and the amino acid derivative contain at least two
functional
groups, one of them being a carboxy group, and the other one being an amine
group or
quaternary amine group. Unless otherwise indicated, the carboxy group and the
amino
group are not derivatized, e.g. with crosslinking agents. The amino acid may
be an
alpha-amino acid, as represented by the following structural formula:
11.31tT+211
In other embodiments, the amino acid may be a beta-, gamma- or delta-amino
acid.
The exemplary proteinogenic amino acid L-arginine is represented by the
following
structural formula:
1H
H2N
NH2
The exemplary non-proteinogenic amino acid derivative L-carnitine is
represented by
the following structural formula:
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HO 0
CI !.
)
0H3
Nisin is a lantibiotic with the following structure:
0
H
N ,e
0 HN
H2N )1?-H-N-) ---1--
T
0
NH S ...,,1 ... y- --, Isil ,õ 0 .
HN0 "ONT NH
S 0
===== 4-NH
N ,. HA 1) CI (:)
X H I'A
\,-)- ,, o NH l 0
0,..õ--.õ1.1,11,,) .õ,,,s õIxlijAõ NH 0 S L
)' S'-"' NH
0
1R1
0 NH2 Otli H'ic)
I 0
H2N
o NH2
NH HN
\µ 0
HN N
Under the reaction conditions according to the method of the present
invention,
R'-COOH groups of amino acids and/or amino acid derivatives may react with R"-
OH
groups of cellulose by forming an ester bond R'-COO-R".
In some embodiments of the invention, polyglucosamine (chitosan) is applied to
the
textile. Chitosan has a structure as shown hereinafter, wherein n indicates
the number
of monomer units as known in the art:
OH I _47. OH
HO ' F-I0 HO OH
N4-= NH2 Nk.
- I n
Under the reaction conditions disclosed herein, chitosan can react with
functional
groups of cellulosic materials resulting in covalent bonds as shown below.
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7
{a)
Covalent bonding
Chitosen treated cellulosic -iolect
When the amino acids and/or amino acid derivatives are used in combination
with
chitosan, under the reaction conditions disclosed herein, R'-COOH groups of
amino
acids and/or amino acid derivatives may react with R"-OH groups of chitosan by
forming an ester bond R'-COO-R'.
Examples
The invention will be further described by the following examples which
illustrate the
preparation of textile materials, without limiting the invention.
AATCC 100-2012 test method for antimicrobial performance:
Antimicrobial performance of antimicrobial textiles according to the invention
were
performed following the AATCC 100-2012 test method. The AATCC 100-2012 test
procedure for antimicrobial performance is described in detail in AATCC
Technical
Manual 2013, p. 166-168.
Briefly, 3 circular swatches of 48 mm diameter were prepared from autoclaved
(121 C,
15 min) textile samples, and a defined number of swatches was added to a 250
ml
Erlenmeyer flask. 1 ml of prepared inoculum (in phosphate buffered water) was
spot
onto the swatches. The test inoculum was P. aeruginosa ATCC 9027 or S. aureus
ATCC
6538 (107 CFU/ml), and the inoculum load was 1% BSA. Contact times were varied
between o mins, 10 mins, 30 mins, and 1 hour. The o minute contact time was
immediately analyzed after inoculation. For the other contact times, the
Erlenmeyer
flask was sealed immediately after inoculation and incubated at 37 C for the
respective
contact times.
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After the defined contact time, loo ml of Dey-Engley Neutralizing broth was
added to
each flask, and the flask was shaken for one minute by hand. A dilution series
was
prepared and each dilution sample was plated on a nutrient agar. Agar plates
were
incubated at 37 C for 24 and 48 hours.
The Log Reduction (R) of bacteria was calculated by:
B [log(number bacteria recovered from the inoculated treated test specimen
swatches
in the jar immediately after inoculation, i.e. at o contact time)] - A
[log(number of
bacteria recovered from the inoculated treated test specimen swatches in the
jar
incubated over the desired contact period)].
AATCC TM-30 (Part III) test method for antimicrobial performance:
The antifungal activity of the textile according to the invention was tested
following
standard test method "AATCC test method 30-2013" and with Aspergillus Niger or
Candida albicans as test organisms ("Test III" of the standard test method).
A 48 hours old culture of C. albicans or A. niger was used for testing. The
grown
culture was scrapped from a Sabouraud dextrose agar medium containing 3%
glucose
and inoculated in 50 mL sterile distilled water with glass beads. The flask
was shaken to
make a suspension and the final density was maintained at 2X106 CFU/ml. The
test
medium (15 mL) was poured onto the sterile petri dish and allowed to solidify.
1 ml of
inoculum was spread over the surface.
A textile sample (3.8 0.5 cm discs, autoclaved prior to testing at 121 C,
15 mins) was
placed onto the agar surface and 0.2 mL of inoculum was added over each
sample. The
plates were incubated at 28 C for 4-5 days. At the end of the incubation
period, the
plates were examined for yeast/fungal growth according to the following
rating:
Growth on specimen Rating
No growth o
Trace of growth 10%) 1
Light growth ( 10-30%) 2
Medium Growth (30-60%) 3
Heavy Growth (60% to complete coverage) 4
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Chemicals
The following chemicals were used in the experiments described hereafter:
L-arginine is known in the art and commercially available, e.g. by Sciencelab.
In the
following examples, L-arginine was provided as a powder with l00% by weight.
L-carnitine was provided by Lonza Specialty Chemicals Switzerland as a powder
with >
98% by weight.
Chitosan was provided in a stock solution by Go Yen Chemical (Goyenchem-102),
Taiwan. Measurements conducted by the inventors showed that this stock
solution
contains about 8% active ingredient, i.e. 8% of chitosan.
Propiconazole is known in the art and commercially available, e.g. Utconazol
(manufactured by Utpan Chempro). Propiconazole can be bound to the textile
material
using a crosslinking agent, in particular a preferably blocked isocyanate
compound,
which results in urethane bonds, or an acrylate based-product. When using
propiconazole, it is preferred to use a crosslinking agent in the liquor, in
particular the
exhaust liquor. It is even more preferred that the formulation of
propiconazole contains
the cross-linking agent or the cross-linking agent is part of the
propiconazole
formulation. In the following examples, propiconazol (Utpan Chempro) was
provided
as a 25% stock solution.
The quaternary ammonium organosilane can comprise an organomethoxysilane,
preferably N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride, as
provided
by Gelest Inc. as a 50% stock solution.
Polyhexamethylene biguanide is known in the art and commercially available. In
the
following examples, polyhexamethylene biguanide (PHMB, Thor GmbH) was provided
as a 20% stock solution.
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An antimicrobial agent can comprise silver cations. In particular embodiments,
the
silver cations are trapped in an inorganic or organic matrix. Preferably, the
inorganic
matrix is an aluminosilicate. Preferably, the organic matrix is a polymeric
matrix. Such
silver-containing microbial agents are known in the art and available on the
market. In
the following examples, Silvadur 930 Flex (0.17% silver cations trapped in a
polymeric
matrix) was provided by Dow Chemical Company.
As a cross-linker, blocked polyisocyanate, e.g. oxime-blocked polyisocyanate,
can be
used. Oxime-blocked polyisocyanate is, for example, provided by Schoeller
Technologies AG.
Textiles
The following textiles were used in the experiments described hereafter:
- l00% viscose: 117 grams per square meter (GSM), yarn count/construction
of
30*30/68*64
- l00% cotton: 40's cotton, 140 GSM
- 50% cotton/50% viscose (CVC blend): 140 GSM
- 65% polyester/35% cotton (PC blend): 165 GSM
Liquor application processes
Unless otherwise specified in the examples below, the liquor application
processes were
conducted as follows:
In a first step ("liquor preparation"), a liquor was prepared in a reaction
mixture
comprising the amino acid(s)/amino acid derivative(s), and/or antimicrobial
agents,
and water. The pH of the reaction mixture was adjusted as specified in the
examples by
application of an acid. The reaction mixture was stirred for a specified time
and
temperature.
Following the liquor preparation, the liquor was used undiluted in the main
liquor
application process, being either an exhaustion or a padding process, with the
specified
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parameters. In some examples, the main liquor application process was followed
by a
secondary application process, being a padding process.
Some of the fabrics were produced using a jigger machine for exhaustion
(Yamuna,
model number Ynoo), and others were produced under laboratory conditions which
closely simulated this process. The inventors estimate that the amount of
chemicals
added to the textile in the exhaust process corresponded to the amount of
chemicals
comprised in a wet pickup of about 100%. Thus, where an agent was comprised in
the
liquor, e.g., at a concentration of 30 gpl (grams per liter), the amount of
the agent on
the textile after the exhaust process was about 3% on-weight-fabric. The
padding
process was carried out with a wet pickup of about 65%. Thus, where an agent
was
comprised in the liquor, e.g., at a concentration of 30 gpl, the amount of the
agent
added to the textile in the padding process was about 1.95% on-weight-fabric.
Drying and curing
Between the main liquor application process and a secondary liquor application
process, the textile was dried, sometimes dried and cured. Following the last
liquor
application process, the textile was dried and cured. Unless otherwise
specified below,
drying was performed for 2 minutes at 120 C, and curing was performed for 2
minutes
at 180 C.
Washing
In some examples, the cured textile was washed several times, as indicated in
the
examples, under the following conditions: The temperature in the washing
cycles was
40 C, and Clax 200S (Johnson Wax Professional) was used as a soap in normal
dosage.
After each washing cycle, the textile was rinsed for 10 minutes with 0.05%
citric acid.
Example 1: Viscose textile treated with L-arginine
A l00% viscose textile was treated with L-arginine in a two-cycle process,
comprising in
the main liquor application cycle an exhaustion process, and in the secondary
process
cycle a padding process.
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A liquor for both the exhaust and the padding processes was prepared
containing 30 or
40 grams L-arginine per liter (gpl). The pH was adjusted to pH 4.5 using
citric acid.
The liquor was stirred at 70 C for 1 hour.
The exhaustion process was carried out with a wet pickup of about 100%,
resulting in
an on-weight-fabric L-arginine add-on of 3.0/4.0%. Exhaustion was performed
with
the undiluted liquor for 1 hour at 60 C, followed by drying at 120 C.
Padding was performed with an L-arginine concentration of 10 gpl in the
liquor. The
padding pickup rate was about 65%. Thus, the total amount of L-arginine added
to the
textile in the exhaust and padding processes together can be estimated to be
3.0/4.0%
+ 0.65% = 3.65/4.65% o.w.f.
After padding, the textiles were dried at 120 C and cured at 180 C. The
cured samples
were washed 10 times in a laboratory washing machine using the non-ionic
detergent
Clax 200 S.
The finishing method and the test results are summarized in the following
table 1.
Table 1: 100% Viscose finishing with L-arginine
Sample ID Arg 30 gpl Arg 40 gpl
Liquor preparation
Arginine 30 gpl 40 gpl
Liquor pH 4.5 4.5
pH adjustor chemical citric acid citric acid
Liquor temp 70 C 70 C
Stirring time 1 hour 1 hour
Main process cycle
Exhaust time 1 hour 1 hour
Exhaust temp 60 C 60 C
Drying temp 120 C 120 C
Secondary process cycle
Arginine 10 gpl 10 gpl
Padding bath temperature room temperature room temperature
Curing temp 180 C 180 C
Washing
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Number of washes 10 10
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after to min
S. aureus 0.53 0.76
P. aeruginosa 2.76 2.76
Log Reduction (R) [Log cf-u/m1] after 30 min
S. aureus 0.86 0.88
P. aeruginosa 2.82 2.92
Log Reduction (R) [Log cf-u/m1] after 1 hour
S. aureus 0.86 1.03
P. aeruginosa 3.82 3.82
As can be derived from table 1, L-arginine confers a significant antimicrobial
performance against gram negative P. aeruginosa of 2.76 log (i.e. > 99%
reduction)
already after 10 minutes. The antimicrobial performance against gram-positive
S.
aureus is about llog after 1 hour (i.e. about 90% reduction). The overall
antimicrobial
performance is not influenced by washing the textile in a detergent, rendering
it
washable and reusable. Such a wash-durability could not be achieved in
experiments
conducted by the inventors using only a padding process and no exhaust
process. The
wash-resistance indicates that the amino acid is covalently bound to the
textile.
Without wishing to be bound by theory, it is believed that the process
conditions,
including exhaustion at elevated temperature and at a low pH, as well as
curing at a
high temperature, during which water is evaporated, facilitate an
esterification reaction
between the carboxy group of L-arginine and the hydroxyl group of the
cellulose
molecules comprised in the viscose textile. Finally, the data indicate a
positive
correlation between the L-arginine concentration used in the liquor and the
antimicrobial efficiency.
Colorimetric test for the detection of L-arginine:
A modified Sakaguchi test was established for detecting and quantifying L-
arginine on
the textile samples of table 1. An adapted Sakaguchi reagent was used, which
consists
of 1-Naphthol and a drop of sodium hypochlorite solution (2.5%). The procedure
for the
modified Sakaguchi test was as follows:
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Preparation offour reagents:
(1)500 mg of 1-Naphthol (Nioo-loG, Sigma-Aldrich) in 100 ml Ethanol,
corresponds to a 0.5% 1-Naphthol solution in Et0H (each time fresh
preparation)
(2) 5 g NaOH in 100 ml deion. water, corresponds to a 5% NaOH solution
(3) Jayelle, corresponds to 2.5% Na0C1 solution
(4) 5 g Urea in 100 ml deion. water, corresponds to a 5% urea solution in
water
Protocol:
- submit textile sample on a petri dish
- textile sample is provided with 1 ml of reagent (1)
- textile sample is provided with 1 ml of reagent (2)
- textile sample is provided with 1 ml of reagent (3)
- textile sample is provided with 1 ml of reagent (4)
A red coloration indicates the presence of L-arginine.
In a first step, a dilution series of L-arginine was tested to estimate the
limit for the
detection. In this series, 1 ml of a 1% L-arginine, cm% L-arginine, o.oi% L-
arginine and
0.001% L-arginine solution were each applied to a 6x6 cm fabric (mass = 408
mg), and
each fabric was subjected to the Sakaguchi reaction. Coloration could be
observed for
0.01% L-arginine solutions and higher concentrated solutions. As 1 ml of a
0.01% L-
arginine solution corresponds to 0.1 mg of L-arginine, applied to 408 mg of
fabric, the
detection limit was estimated to be about 0.025% arginine o.w.f.
The washed textiles of table 1 were tested according to the Sakaguchi test,
and the
obtained colorations compared to the dilution series. The o.w.f. concentration
of L-
arginine of the sample "Arginine 30 gpl" could be estimated to be between 0.25-
2.5% of
arginine on viscose, and the o.w.f. concentration of L-arginine of the sample
"Arginine
gpl" could be estimated to be higher than 2.5% of arginine on viscose.
The Sakaguchi test confirmed that L-arginine was stably bound to the textile
samples in
a wash-durable manner.
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Example 2: Viscose textiles treated with L-carnitine
A 100% viscose textile was treated with L-carnitine in a two-cycle process,
the main
process cycle comprising an exhaust process and the secondary process cycle
comprising a padding process.
A liquor was prepared by dissolving in water 40 gpl L-carnitine provided as
powder,
and adjusting the pH to pH 4.5 with citric acid. The liquor was stirred for 30
minutes at
60 C before being applied to the textile samples by means of exhaustion,
followed by
drying at 120 C, and padding.
The exhaustion process was carried out with a wet pickup of about 100%,
resulting in
an on-weight-fabric L-carnitine add-on of 4.0%. The padding pickup rate was
about
65%. Thus, the total amount of L-carnitine added to the textile in the exhaust
and
padding processes together can be estimated to be 4.0% + 2.6% = 6.6% o.w.f.
After padding, the textile was dried at 120 C and cured at 180 C for 2
minutes. After
curing, one treated sample was tested directly for antimicrobial activity,
whereas a
second treated sample was washed 10 times, as described above, before testing
the
antimicrobial activity.
The prepared textile samples were tested according to AATCC 100-2012 as
described
above. Further, the prepared textile samples were tested according AATCC TM-30
(Part
III) against Candida albicans ATCC10231 as described above.
Table 2: 100% Viscose finishing with L-carnitine, wash-performance
Carnitine, Carnitine,
Sample ID unwashed washed
Liquor preparation
L-Carnitine 40 gpl 40 gpl
Liquor pH 4.5 4.5
pH adjustor chemical citric acid citric acid
pH adjusting dosage 1 gpl 1 gpl
Liquor temp 6o C 6o C
Stirring time 30 min 30 min
Main process cycle
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Exhaust time 1 hour 1 hour
Exhaust temp 60 C 60 C
Drying temp 180 C 180 C
Secondary process cycle
Padding bath temperature 60 C 60 C
Number of nib and dip into
padding bath 20 20
Curing temp 180 C 180 C
Washing
Number of washes o 10
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after 10 min
S. aureus 0.13 0.13
P. aeruginosa 0.12 0.1
Log Reduction (R) [Log cf-u/m1] after 30 min
S. aureus 0.27 0.23
P. aeruginosa 2.9 2.82
Log Reduction (R) [Log cf-u/m1] after 6o min
S. aureus 0.45 0.44
P. aeruginosa 3.61 3.54
Antimicrobial activity (AATCC TM-30 (Part III))
Moderate resistant Very mild resistant
C. albicans - 48 hours contact (rating: 3) (rating: 1)
As can be derived from table 2, L-carnitine confers a high antimicrobial
performance
against P. aeruginosa of 2.82 log (i.e. > 99% reduction) after 30 minutes of
incubation.
On the other hand, the antimicrobial performance against S. aureus is
significantly
lower. The overall antimicrobial performance is not influenced by washing the
textile at
40 C in a detergent, showing that it is wash-durable and reusable. Such a
wash-
durability could not be achieved in experiments conducted by the inventors
using only
a padding process and no exhaust process. The wash-resistance indicates that L-
carnitine can also be covalently bound to the textile, possibly in terms of an
ester group
between the carboxy group of L-carnitine and the hydroxyl group of the
cellulose
molecules comprised in the viscose textile. Furthermore, the test results
regarding C.
albicans demonstrate that textiles treated with L-carnitine have an antifungal
activity.
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Example 3: Viscose textiles treated with combinations of L-arginine and
chitosan
A l00% viscose textile was treated with chitosan or with L-arginine and
chitosan in a
two-cycle process, comprising in the main liquor application cycle an exhaust
step, and
in the secondary process cycle a padding step.
A liquor for the exhaustion step was prepared containing 40 grams chitosan
stock
solution (8%) per liter or 40 grams of chitosan stock solution and 60 grams of
L-
arginine per liter. The pH was adjusted to pH 4.5 using citric acid or acetic
acid. The
liquor was stirred at 70 C for 1 hour. The exhaustion process was carried out
with a wet
pickup of about 100%, resulting in a chitosan add-on of 0.32% o.w.f. and an L-
arginine
add-on (where applicable) of 6% o.w.f. Exhaustion was performed for 1 hour at
60 C,
followed by drying at 120 C.
The liquor used in the padding process contained 10 grams chitosan stock
solution
(8%) per liter or 10 grams of chitosan stock solution and 30 grams of L-
arginine per
liter. Padding pickup rate of the secondary process cycle was about 65%. Thus,
the total
amount of chitosan added to the textile in the exhaust and padding processes
together
can be estimated to be 0.32% + 0.052% = 0.372% o.w.f. The total amount of L-
arginine
added to the textile in the exhaust and padding processes together (where
applicable)
can be estimated to be 6% + 1.95% = 7.95% o.w.f.
After padding, the textiles were dried and cured at 180 C. The cured samples
were
washed 10 times in a laboratory washing machine using the non-ionic detergent
Clax
200 S.
The finishing method and the test results are summarized in the following
table 3.
Table 3: l00% Viscose finishing with L-arginine or L-arginine and chitosan
Sample ID Chit Chit + Mg
Liquor preparation
Arginine 6o gpl
Chitosan stock solution 40 gpl 40 gpl
Liquor pH 4.5 4.5
pH adjustor chemical citric acid acetic acid
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Liquor temp 70 C 70 C
Stirring time 1 hour 1 hour
Main process cycle
Exhaust time 1 hour 1 hour
Exhaust temp 60 C 60 C
Drying temp 120 C 120 C
Secondary process cycle
Arginine 30 gpl
Chitosan stock solution 10 gpl 10 gpl
Padding bath temperature room temperature room temperature
Curing temp 180 C 180 C
Washing
Number of washes 10 10
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after to min
S. aureus 0.8 2.47
oP. aeruginosa 2.71 2.92
Log Reduction (R) [Log cf-u/m1] after 30 min
S. aureus 1.11 5.17
P. aeruginosa 3.52 4.82
Log Reduction (R) [Log cf-u/m1] after 1 hour
S. aureus 1.13 5.17
P. aeruginosa 4.82 4.82
As can be derived from table 3, the combination of L-arginine and chitosan
confers an
extraordinary high antimicrobial performance against P. aeruginosa of at least
2.47 log
(i.e. > 99% reduction) after 10 minutes of incubation, and against S. aureus
of at least
2.92 log. After 30 minutes of incubation, the reduction rate increases to 5.17
log and
4.82 log. Such high performances could not be achieved using the antimicrobial
agent
chitosan only.
Example 4: Viscose textiles treated with combinations of L-arginine, L-
carnitine and
chitosan
A l00% viscose textile was treated with combinations of L-arginine, L-
carnitine and
chitosan in a one-cycle exhaustion process. Chitosan was provided as aqueous
stock
solution comprising 8% water-soluble chitosan.
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The concentrations of actives in the exhaust liquor resulted in a
concentration of
0/0.56% chitosan o.w.f., 7% L-arginine o.w.f., and 7% L-carnitine o.w.f. After
exhaustion, the textiles were dried at 120 C and cured at 180 C for 2
minutes.
The thus prepared textile samples were washed and tested according to AATCC
100-
2012 as described above for example 1.
Table 4: 100% Viscose finishing with L-arginine and L-carnitine, or L-
arginine, L-carnitine,
chitosan
L-arginine, L- L-arginine, L-carnitine,
Sample ID carnitine chitosan
Liquor preparation
Chitosan stock solution o gpl 70 gpl
Carnitine 70 gpl 70 gpl
Arginine 70 gpl 70 gpl
Liquor pH 4.5 4.5
pH adjustor chemical Acetic acid Acetic acid
Liquor temp 50 C 50 C
Stirring time 1 hour 1 hour
Main process cycle
Exhaust time 1 hour 1 hour
Exhaust temp 50 C 50 C
Curing temp 180 C 180 C
Washing
Number of washes 10 10
Testing results 30 Mins(AATCC-loo): Log Reduction (R) [Log cfuhnl]
S. aureus 3.47 4.47
P. aeruginosa 2.15 4.06
The combination of L-carnitine and L-arginine in the exhaust process results
in a
significant increase in antimicrobial activity compared to the use of only one
of L-
carnitine and L-arginine against S. aureus. The further addition of chitosan
again
significally increases the antimicrobial activity, to at least 4 log (i.e., >
99.99%
reduction) after 30 min contact time.
Example 5: Different textiles treated with combinations of L-arginine,
carnitine,
chitosan, and optionally silver cations
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Different textiles were treated according to the invention, namely a textile
consisting of
l00% viscose, a textile consisting of l00% cotton, a textile consisting of a
blend of 50%
cotton and 50% polyester (CVC), and a textile consisting of a blend of 65%
polyester
and 35% cotton (PC).
A liquor comprising 120 gpl chitosan stock solution (8%), 70 gpl L-arginine
and 70 gpl
L-carnitine, and optionally 10 gpl Silvadur 930 Flex was applied to the
respective textile
material in a main process cycle comprising exhaustion, drying at 120 C and
curing at
180 C, followed by a secondary process cycle comprising padding, drying at
120 C and
curing at 180 C, using the same liquor as for the exhaustion process.
The concentrations of actives in the liquor resulted in an estimated add-on of
1.584%
chitosan o.w.f, 11.55% L-arginine o.w.f., 11.55% L-carnitine o.w.f., and
0.002805%
silver o.w.f (where applicable).
The prepared textile samples were tested according to AATCC 100-2012 as
described
above.
Table 5: 100% Viscose or 100% cotton finishing with combinations of L-
arginine, L-carnitine,
chitosan and silver ions
100% 100% 100% 100%
viscose viscose, cotton cotton,
Sample ID +Ag +Ag
Liquor preparation
Chitosan stock solution 120 gpl 120 gpl 120 gpl 120 gpl
Carnitine 70 gpl 70 gpl 70 gpl 70 gpl
Arginine 70 gpl 70 gpl 70 gpl 70 gpl
Silvadur 930 Flex o gpl 10 gpl o gpl 10 gpl
Liquor pH 4.5 4.5 4.5 4.5
pH adjustor chemical Acetic acid Acetic acid Acetic acid
Acetic acid
Liquor temp 50 C 50 C 50 C 50 C
Stirring time 1 hour 1 hour 1 hour 1 hour
Main process cycle
Exhaust time 1 hour 1 hour 1 hour 1 hour
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Exhaust temp 70 C 70 C 70 C 70 C
Curing temp 180 C 180 C 180 C 180 C
Secondary process cycle
Padding bath temperature 50 C 50 C 50 C 50 C
Curing temp 180 C 180 C 180 C 180 C
Washing
Number of washes 10 10 10 10
Testing results 30 Mins(AATCC-10o): Log Reduction (R) [Log cfu/m1]
S. aureus 5.34 5.64 4.83 5
P. aeruginosa 4.91 4.91 4.91 4.91
Table 6: CVC and PC finishing with combinations of L-arginine, L-carnitine,
chitosan and
silver ions
Sample ID CVC CVC, +Ag PC PC, +Ag
Liquor preparation
Chitosan stock solution 120 gpl 120 gpl 120 gpl 120 gpl
Carnitine 70 gpl 70 gpl 70 gpl 70 gpl
Arginine 70 gpl 70 gpl 70 gpl 70 gpl
Silvadur 930 Flex o gpl 10 gpl o gpl 10 gpl
Liquor pH 4.5 4.5 4.5 4.5
pH adjustor chemical Acetic acid Acetic acid Acetic acid
Acetic acid
Liquor temp 50 C 50 C 50 C 50 C
Stirring time 1 hour 1 hour 1 hour 1 hour
Main process cycle
Exhaust time 1 hour 1 hour 1 hour 1 hour
Exhaust temp 70 C 70 C 70 C 70 C
Curing temp 180 C 180 C 180 C 180 C
Secondary process cycle
Padding bath temperature 50 C 50 C 50 C 50 C
Curing temp 180 C 180 C 180 C 180 C
Washing
Number of washes 10 10 10 10
Testing results 30 Mins(AATCC-100): Log Reduction (R) [Log efu/m1]
S. aureus 3.83 4.05 3.12 3.88
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P. aeruginosa 4.91 4.91 4.91 4.91
As can be derived from the above tables 5 and 6, all four textile materials
that were
tested exhibited high antimicrobial performances, of at least 3 log (i.e. >
99.9%
reduction) after 30 min contact time after 10 washes in nonionic detergent
Clax 200 S.
The addition of silver ions further increased the antimicrobial action against
S. aureus.
Overall, treated viscose textiles exhibited a higher antimicrobial activity
than other
textile materials. The antimicrobial performance decreased in the following
order:
viscose > cotton > CVC blend > PC blend. In view of the decreasing
concentration of
cellulose molecules, and thus of reactive hydroxyl groups, with respect to the
CVC blend
and the PC blend, it may be possible that the functional groups of the
textiles are
decisive for a stable binding of L-arginine, L-carnitine and chitosan.
Finally, sample "PC, +Ag" showed to be partially resistant against A. niger,
when tested
according to AATCC-30 (7 days contact time) (not shown in the tables).
Example 6:100% viscose textiles treated with combinations of L-arginine and
chitosan in different types of acids
l00% viscose textile samples were treated with L-arginine and chitosan in a
two-cycle
process, comprising in the main liquor application cycle an exhaust step, and
in the
secondary process cycle a padding step. The pH of the liquor was adjusted
either with
acetic acid, citric acid or hydrochloric acid.
A liquor comprising 40 gram per liter (gpl) chitosan stock solution
(concentration: 8%)
and 60 gpl L-arginine was applied in a main process by exhaustion, resulting
in a
concentration of about 0.32% chitosan o.w.f. and 6% L-arginine o.w.f.
Exhaustion was
followed by drying at 120 C. A secondary liquor application cycle comprised
padding,
drying at 120 C and curing at 180 C. The padding liquor comprised 10 gram
per liter
(gpl) chitosan stock solution and 30 gpl L-arginine, resulting in an
additional add-on of
0.052% chitosan o.w.f. and 1.95% L-arginine o.w.f. Total actives add-on in
both process
cycles together was therefore 0.372% chitosan o.w.f. and 7.95% L-arginine
o.w.f.
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Exhaustion was followed by drying at 120 C. After drying, the samples were
washed 30
times at 40 C with Clax 200 S before testing the antimicrobial activity.
Table 7: Combinations of L-arginine and chitosan with different acids
Chit-Arg acetic Chit-Arg citric
Sample ID acid acid Chit-Mg
HC1
Liquor preparation
Chitosan stock solution 40 gpl 40 gpl 40 gpl
Arginine 6o gpl 6o gpl 6o gpl
Liquor pH 4.5 4.5 4.5
pH adjustor chemical Acetic acid Citric acid HC1
Ph adjusting dosage 26 gpl 30 gpl 33 gpl
Liquor temp 70 C 70 C 70 C
Stirring time 1 hour 1 hour 1 hour
Main process cycle
Exhaust time 1 hour 1 hour 1 hour
Exhaust temp 60 C 60 C 60 C
Drying temp 120 C 120 C 120 C
Secondaryprocess cycle
Chitosan stock solution 10 gpl 10 gpl 10 gpl
Arginine 30 gpl 30 gpl 30 gpl
Padding bath
temperature r.t. r.t. r.t.
Curing temp 180 C 180 C 180 C
Washing
Number of washes 30 30 30
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after 10 Mins
S. aureus 2 1.5 0.57
P. aeruginosa 2.1 1.74 0.85
Log Reduction (R) [Log cf-u/m1] after 30 Mins
S. aureus 3.8 2.55 1.1
P. aeruginosa 3.5 3.15 1.42
Log Reduction (R) [Log cf-u/m1] after 6o Mins
S. aureus 4.3 2.89 1.8
P. aeruginosa 4 3.5 2.45
The results of table 7 show that the highest antimicrobial performance could
be
obtained using acetic acid for adjusting the pH of the liquor. Citric acid
performs
slightly worse, which may be due to the build-up of free carboxylic groups,
i.e. negative
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charges on the textile. On the other hand, hydrochloric acid may affect the
textile, in
particular cellulosic textiles.
Example 7: loco% Polyethylene textiles treated with combinations of L-
arginine, L-
carnitine, chitosan and further antimicrobial agents
A thin fabric was prepared by the method according to the present invention.
A l00% polyester textile (22 GSM) was treated with L-arginine in a one-cycle
process,
comprising a padding process only.
The liquor for the padding processes was prepared containing 5 gpl each of L-
arginine
and L-carnitine. Furthermore, the liquor contained 1 gpl of a 25%
propiconazole stock
solution, 1.5 gpl of a 25% PHMB stock solution, 25 gpl of an 8% chitosan stock
solution,
and 8% of Silvadur 930 Flex (comprising 0.17% of silver). The pH was adjusted
to pH
6.5 using acetic acid. Furthermore, the liquor comprised 4 gpl of isopropanol.
The
liquor was stirred at 50 C for 1 hour.
The padding process was carried out with a wet pickup of about 5o%. The
resulting
add-ons of chemicals can be gathered from the table below. Padding was
followed by
drying at loo C for 3 minutes and curing at the same temperature for 2
minutes.
The cured samples were tested for antimicrobial performance, and the test
results are
compiled in table 8.
Table 8: Combinations of L-arginine, L-carnitine and chitosan with further
antimicrobial
agents
Plain dotted l00% PE
Total meter: 1000
Fabric GSM: 22
details: GLM: 30.8
Width, meter: 1.4
Total weight, kg: 31
Total pad liquor lit: 15
Process
parameters %pickup, padding: 50%
Pad (2 dip--> 2 nip) ---> dry at loo C for 3 min ---> cure at loo C for 2
min
Padding Chemicals (stock Quantity, . Add-on,
gm/lit A actives
liquor solution or kg mg/sq.meter
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powder)
Propiconazol 1 0.015 25% 3.8500
Polyhexamethylene
1.5 0.023 20% 4.6200
biguanide
Chitosan 25 0.385 8% 30.8000
Pad Silvadur 930 Flex 8 0.123 0.17% 0.2094
application L-arginine 5 0.077 100.00% 77.0000
only L-carnitine 5 0.077 100.00% 77.0000
0.0000
Isopropanol 4 (evaporates)
Acetic acid (pH
adjustment to pH 0.3 0.005 100% 0.0000
6.5)
Total add-on, mg/sq. mtr
195.4794
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after 10 Mins
S. aureus 2.35
E. coli 1.5
Log Reduction (R) [Log cf-u/m1] after 4 hours
S. aureus 4.15
E. coli 4.78
Log Reduction (R) [Log cf-u/m1] after 8 hours
S. aureus 5.39
E. coli 5.54
Log Reduction (R) [Log cf-u/m1] after 24 hours
S. aureus 5.24
E. coli 4.09
Although the textile was only treated with padding and, because of its low
weight, was
cured only at wo C, the antimicrobial performance was found to be high.
Example 7: loco% viscose textiles treated with combinations of L-arginine and
chitosan by padding
l00% viscose textile samples were treated with L-arginine and chitosan in a
one-cycle
process, comprising in the main liquor application cycle a padding step, and
in the
secondary process cycle a padding step. The pH of the liquor was adjusted to
pH 7 with
hydrochloric acid.
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The padding liquor comprised 40 gram per liter (gpl) chitosan stock solution
(concentration: 8%) and 5 gpl L-arginine, resulting in an additional add-on of
0.052%
chitosan o.w.f. and 0.325% L-arginine o.w.f.
The padding bath temperature was kept at room temperature. After padding, the
textile
samples were dried at 150 C for 2 minutes and cured at 180 C for 2 minutes. In
the
following the textiles were washed 5 times in water, each washing cycle
performed over
minutes at 27 C, and tested according to AATCC 100-2012, as described above.
The
process parameters and test results are summarized in table 9.
Table 9: Wash-durability after padding
Sample ID Chit-Mg unwashed Chit-Mg
washed
Liquor preparation
Chitosan stock solution 40 gpl 40 gpl
Arginine 6o gpl 6o gpl
Liquor pH 7 7
pH adjustor chemical HC1 HC1
Main process cycle
Padding bath
temperature r.t. r.t.
Curing temp 180 C 180 C
Washing
Number of washes 0 5
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after 30 Mins
S. aureus 1.99 3.29
Log Reduction (R) [Log cf-u/m1] after 6o Mins
S. aureus 4.28 4.28
The results according to table 9 indicate that a padding process allows the
production
of an antimicrobial textile with wash-durable performance to a certain extent.
However, the performance decreases slightly upon washing the textile, while an
exhaustion process renders textiles highly wash-durable and reusable as
antimicrobial
textile, as described above. Therefore, application of an exhaust process in
the main
process cycle is currently preferred.
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Example 8: Cotton textile treated with L-arginine
A l00% cotton textile was treated with L-arginine in a two-cycle process,
comprising in
the main liquor application cycle an exhaustion process, and in the secondary
process
cycle a padding process.
A liquor for both the exhaust and the padding processes was prepared
containing 120
grams L-arginine per liter (gpl). In order to evaluate any effect of the pH on
the wash-
durable performance a test series with samples having a pH of 4.0, 4.5, 5.0,
5.5, and 6.0
was investigated. The pH was adjusted using acetic acid. The liquor was
stirred at 70 C
for 1 hour.
The exhaustion process n was performed with the undiluted liquor for 1 hour at
60 C,
followed by drying at 120 C.
Padding (2 nip and 2 dip) was performed at room temperature with an L-arginine
concentration of 120 gpl in the liquor.
After padding, the textiles were dried at 120 C and cured at 180 C. The
cured samples
were washed 5 times in a laboratory washing machine using the non-ionic
detergent
Clax 200 S. After every Clax wash, the fabric was washed with water followed
by a
0.05% citric acid wash. Then the fabric was dried at 150 C for 2 minutes. The
samples
were tested for their antimicrobial efficiency before the washing and after
each washing
cycle.
The test results are summarized in the following table to.
Table to: 100% cotton finishing with L-arginine
Sample ID Arg 120 -1 Arg 120 -2 Arg 120 -3 Arg 120 -4 Arg 120 -5
Liquor preparation
Arginine 120 gpl
Liquor pH 4.0 4.5 5.0 5.5 6.o
pH adjustor chemical acetic acid
Liquor temp 70 C
Stirring time 1 hour
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Main process cycle
Exhaust time 1 hour
Exhaust temp 60 C
Drying temp 120 C
Secondary process cycle
Arginine 120 gpl
Liquor pH 4.0 4.5 5.0 5.5 6.0
Padding bath
room temperature
temperature
Curing temp 180 C
Washing
Number of washes 5
Antimicrobial activity (AATCC 100-2012)
Log Reduction (R) [Log cf-u/m1] after 24 hours against E. coli
Wash cycle
0 (unwashed) > 4.41 > 4.41 > 4.41 > 4.41 > 4.41
1 1.93 3.33 > 4.41 > 4.41 > 4.41
2 1.87 2.08 3.96 > 4.41 3.45
3 1.81 1.69 2.15 > 4.41 2.81
4 1.79 1.70 2.11 3.46 2.76
5 1.60 1.67 2.07 3.07 2.63
Untreated control -0,35
As can be derived from table to, L-arginine in an amount of 12% without any
additional antimicrobial agent confers a significant antimicrobial performance
against
E. coil of > 4.41 log (i.e. > 99.99 % reduction) after 24 hours.
Also, from table 143 can be derived that the wash-durability is influenced by
the pH of
the liquor. The highest wash-durability was observed for sample Arg 120 -4,
wherein
the pH of the liquor was 5.5 providing for an antimicrobial performance
against E. coil
of > 4.41 log even after the third wash cycle.
