Note: Descriptions are shown in the official language in which they were submitted.
DESCRIPTION
ANTIMICROBIAL FIBER, RESIN, AND METHOD FOR PRODUCTION THEREOF
Technical Field
This invention relates to an antimicrobial
polyacrylonitrile or polyester fiber or resin, and to a
method in which a polyacrylonitrile or polyester fiber or
resin is processed to provide antimicrobial properties.
To date, antimicrobial materials have even been
propagated and utilized everywhere in life. Further, they
are becoming more indispensable to food industries such as
meat industries, areas such as medical treatment, and
manufacturing industries such as medical supplies.
Furthermore, they may be considered that as society is aging,
their importance will increase even more in the future.
B~ckg~o~ Art
Polyacrylonitrile fibers or resins (hereinafter referred
to as PAN) are highly general-purpose, and have been widely
used in, needless to say, clothes, and other life amenities
including toiletry products. Consequently, studies
concerning the antimicrobial processing of PAN are active,
and various methods have been proposed, but there has not yet
been a conclusive method. An idea wherein a PAN which has
sulfonic group and/or sulfonate group in the structure
thereof is treated with metallic silver or a silver compound
- 2 ~
to impart antimicrobial properties thereto has been well-
known for a long time. However, because the reaction of a
silver ion looks like proceeding fast, no literature can be
found which investigates the reaction conditions in detail.
As a result, in the prior art technique, its effectiveness
can be proven only by increasing the amount of silver to be
adhered by using a fiber with an increased amount of sulfonic
group and/or sulfonate group, or by increasing the amount of
carboxyl group in the fiber by partial hydrolysis of the PAN.
On the other hand, polyester fibers and resins (hereinafter
referred to as PET) are also highly general-purpose
materials, being extensively utilized in various industrial
fields, not to mention clothes. With reference to the PET,
there is almost no effective method for imparting
antimicrobial properties to the material by surface treatment
after molding, thus the development of such a technique has
long been desired.
In Japanese Patent Laid-Open (KOKAI) No. 52-92,000
~1977), a method for providing antimicrobial properties to
mainly PAN is described. According to this, the useful
silver concentration range is not less than 0.1
milliequivalent (meq)/g fiber, and 0.69 meq/g fiber of silver
is used in its working example. This means that a large
amount of silver, i.e. 1~ and 7% by weight per fiber is used,
respectively. This contains a practical problem from the
economic viewpoint.
_ 3 ~ ? ~ 3
When antimicrobial properties are provided to PAN, it
was required for the prior art techniques to prepare fibers
in a special form or to perform a treatment such as
hydrolysis previously. These treatment are not only
complicated procedures, but also seriously affect the
strength and physical properties of the fiber. Further, a
use of a large amount of silve., as described above, is also
a problem. The inventors have further found in the research
on the PANs to which silver is adhered by means of the
conventional method that the silver is unevenly adhered to
them, especially the silver separated out as metallic silver
aggregates to form particles of large diameter. Accordingly,
it turned out that the specific surface area of the silver
adhered to the PAN is small, and a large portion of the
silver particle will be easily fallen off by several
repetitions of washing. It has been also understood that,
due to uneven adhering, no stable effect can be obtained
without using a large amount of silver.
On the other hand, the PET has no chemically active
group in the structure thereof. In only a certain case,
there exist those having sulfonic group and/or sulfonate
group in the structure thereof in which sulfonic group and/or
sulfonate group is introduced for the purpose of improving
dyeing properties, i.e., so-called cationic dye dyeable type
polyester fibers or resins ~hereinafter referred to as
CDPET). However, only a quite small amount of sulfonic group
and/or sulfonate group can be introduced without adversely
affecting the performance of the fibers or resins.
Consequently, in prior art technique has not been considered
the surface treatment of fibers or resins wi~h silver or a
silver compound as a practical method, so as severely limited
method that an antimicrobial compound is kneaded into PET to
provide antimicrobial properties has been employed hitherto.
As described above, PETs having sulfonic group and/or
sulfonate group in the fiber ~CDPET) for the purpose of
improving the dyeing properties have been known. However, if
carrying out the treatment for adhering or bonding to them a
silver compound or metallic siLver by the conventional
manner, almost no silver is adhered t~o the fiber or resin,
otherwise even if silver is adhered, silver is adhered in an
uneven form, the specific surface area of silver is small and
the aggregated silver is easily separated off with washing
and the like, resulting in an insufficient antimicrobial
activity and failure to show a continuous effect.
Disclosure of Invention
The inventors have studied about a method for uniformly
adhering or bonding to PAN or CDPET silver with avoiding the
aggregation. As a result, the present invention has been
accomplished.
This invention relates to:
-- 5 -- ,'." .3~ .'~, ~ o~ ~
(1) an antimicrobial fiber or resin of polyacrylonitrile or
polyester containing 1 to 1,000 ppm, preferably 10 to 1,000
ppm, of silver in the form of silver sulfonate,
(2) a process for producing an antimicrobial fiber or resin
of polyacrylonitrile or polyester comprising reacting a fiber
or resin of polyacrylonitrile or polyester having a sulfonic
group and/or a sulfonate group in the structure thereof with
a water-soluble silver compcund in water at a temperature not
lower than the glass transition temperature of the
polyacrylonitrile or the polyester,
(3) a process for producing an antimicrobial fiber or resin
of polyacrylonitrile or polyester comprising reacting a fiber
or resin of polyacrylonitrile or polyester having a sulfonic
group and/or a sulfonate group in the structure thereof with
a water-soluble silver compound in water at a temperature not
lower than the glass transition temperature of the
polyacrylonitrile or the polyester, and then treating it with
a reducing agent,
(4) the process of the above-mentioned (2) or (3), wherein
the fiber or resin of polyacrylonitrile or polyester is
reacted with the water-soluble silver compound in water at a
pH not higher than 5, and
(5) an antimicrobial fiber or resin of polyacrylonitrile or
polyester obtained by the process of the above-mentioned (2),
(3), or (4).
- 6 ~
As the PANs (polyacrylonitrile fibers and resins~ for
use in this invention, it is possible to use the fibers or
resins with the amount of sulfonic group and/or sulfonate
group especially increased, but it is sufficient to use
commercially available PANs having a sulfonic group and/or a
sulfonate group such as Cashmilon, Toraylon, Exlan, Beslon,
Vonnel, and Kanekalon. In addition to the fiber in the form
of yarn, cloth and the like, resin in various forms such as
sheet, powder and granule may be used as the PAN, and the PAN
in any form may be treated in accordance with the method of
this invention.
The PANs which are used in this invention usually are
copolymers comprising at least 60 mol% of acrylonitrile and
unsaturated compounds containing vinyl group copolymerizable
with the acrylonitrile. Any PAN can be used in this
invention as long as the PAN contains such an amount of
sulfonic group and/or sulfonate group that 1 to 1,000 ppm or
more of silver can be adhered or bonded thereto when the
treatment of the above-mentioned (2), (3) or (4) is carried
out.
As the CDPETs (polyester fibers and resins having
sulfonic group and/or sulfonate group in the structure
thereof) for use in this invention, it is possible to use the
fibers or resins with the amount of sulfonic group and/or
sulfonate group especially increased, and commercially
available cationic dye dyeable type polyesters (CDPET) or
polyester cloths or yarns mixed with raw CDPET yarns can be
used. Also, resins in various forms such as sheet, powder
and granule can be used.
Usually the CDPETs are polyester fibers or resins which
are obtained mainly by the dehydrating polycondensation
reaction of terephthalic acid and/or phthalic acid
(derivatives) with polyhydric alcohols and have sulfonic
group and/or sulfonate group in the structure thereof. Any
CDPET can be used as long as the CDPET contains such an
amount of sulfonic group and/or sulfonate group that 1 to
1,000 ppm or more of silver can be adhered or bonded thereto
when the treatment of the above-mentioned item (2), (3) or
(4) is carried out. Phthalic acid, isophthalic acid, p-
hydroxybenzoic acid, 2-sulfoterephthalic acid, 5-
sulfoisophthalic acid, and the like, are used as the phthalic
acid (derivatives), and ethylene glycol, pentaerythritol,
oligoethylene glycols and the like are used as the polyhydric
alcohols.
The water-soluble silver compound to be used is usually
~ silver nitrate, but other compounds such as silver fluoride,
r silver perchlorate, silver sulfate, silver lactate, silver
tetrafluoroborate and silver acetate may also be used.
The glass transition temperature of the PAN depends on
the kind of PAN, but generally is in the range of 60 to 90C.
Therefore, when the PAN is used, a temperature not lower
than the glass transition temperature of the PAN may be
- 8 - ~ `3~ 3 ~
obtained by setting a reaction temperature (a treating bath
temperature) to not lower than 90C in general. The reaction
may also be carried out at normal pressure, while boiling the
treating bath. There is also no problem in carrying out the
reaction at a temperature of not lower than 100C under
pressure. The reaction temperature is not specifically
limited as long as it is not lower than the glass transition
temperature of the PAN, but in order not to impair the
characteristics of the PAN, it is preferably not higher than
130C, especially in the range of the glass transition
temperature to 100C.
On the other hand, the glass transition temperature of
the commercially available CDPET depends on the kind of
CDPET, but is generally in the range of 70 to 90C.
Therefore, when the CDPET is used, a temperature not lower
than the glass transition temperature of the CDPET may be
obtained by setting the reaction temperature (a treating bath
temperature) to not lower than 90C in general. The reaction
may be carried out at normal pressure, while boiling the
treating bath. There is also no problem carrying out the
reaction at a temperature of not lower than 100C under a
pressure. The reaction temperature is not specifically
limited as long as it is not lower than the glass transition
temperature of the CDPET but in order not to impair the
characteristics of the CDPET, it is preferably not higher
than 200C, especially in the range of 90 to 140C.
~J ~
In the explanation hereinafter, the term "PAN" and the
term "CDPET" are referred to collectively as "CDFR".
For carrying out the process of the present invention,
generally the CDFR is added to an aqueous solution of the
water-soluble silver compound, and the reaction is performed
by heating it to a temperature not lower than the glass
transition temperature of the CDFR added, with stirring. The
reaction may also be carried out by preheating an aqueous
solution of the water-soluble silver compound to a
temperature not lower than the glass transition temperature
of the CDFR, and then adding the CDFR. The bath ratio (CDFR:
the aqueous solution of the water-soluble silver compound) is
suitably in the range of 1 : 10 to 40 (weight ratio). The
heat treatment period is not specifically limited, but
generally it is sufficient to carry out the heat treatment
for 10 to 60 minutes.
The amount of the water-soluble silver compound to be
added depends on the amount of silver desired to be adhered,
klnd of CDFR, and the reaction conditions. In the case of
CDFRs which are generally commercially available, the water-
soluble silver compound may be used in such an amount as 1 to
5 times the amount of silver desired to be adhered or bonded
to the CDFR. When the PAN is used, it is preferable in order
not to impair the characteristics of the PAN, such as the
feeling of the fiber, to pay attention to the control of the
bath temperature after the treatment. To be specific, it is
-- 1 0 ~ 4 b~
preferred to cool the bath gradually until the bath
temperature becomes lower than 60C.
By the method as described above, an antimicrobial CDFR
of the present invention having silver sulfonate group can be
obtained.
The antimicrobial CDFR of the present invention having
silver sulfonate group has less coloration, and has almost no
tendency to color change by sunlight and reduction by
detergent, thus it is very advantageous considering practical
application to living hygienic fields.
In particular, when the coloration causes a problem,
such as in the case of white cloth, it is preferable to carry
out the reaction in an acidic aqueous solution by adjusting
the pH value. The pH adjustment can be performed by the use
of a buffer, an acid or the like, but the use of a compound
which reacts with silver to form a precipitate such as
hydrochloric acid is not preferable. Generally the pH value
is adjusted with acetic acid, lactic acid, or an acetic acid
buffer. The pH level preferably ranges from 1 to 5.
When an acid is used alone, the concentration of the
acid is defined by the pH. The concentration of the buffer
solution is not specifically limited, but generally it is
sufficient to be 0.01 mol/l (acetic acid buffer) more or
less. The antimicrobial CDFR thus obtained, if necessary,
can be further reduced to provide CDFR with fine silver
particles adhered thereto. If the reduction treatment is
carried out, a reducing agent having a relatively strong
reducing power is preferably used. For example,
hydroxylamine, hydrazine, glucose-caustic alkali, sodium
boron hydride, or the like may be used as the reducing agent.
The reduction treatment can be carried out by the use of an
aqueous solution of the reducing agent, preferably in a
concentration in the range of 0.05 to 5% by weight preferably
in an amount of 2 to 30 times the weight of the antimicrobial
CDFR having silver sulfonate, and preferably heating to 95 to
100C for five minutes or more. The antimicrobial CDFR
having silver sulfonate and the antimicrobial CDFR with fine
silver particles adhered thereto thus obtained have a
sufficient antimicrobial effect, even when silver content is
a low content in the rangé of 1 to 1,000 ppm, preferably 10
to 1,000 ppm. As described above, in the prior art, it was
required for providing antimicrobial properties to fibers
that the fibers contain silver at a high content of 1% or 7%.
In contrast, according to the present invention, the resins
or the fibers unexpectedly exhibit strong antimicrobial
effects, and excel in wash fastness, in spite of a low
content of silver in the range of 1 to 1,000 ppm. This is
because, in the antimicrobial CDFR of the present invention,
silver is uniformly adhered or bonded onto the fibers or
resins and silver separated as metallic silver does not
aggregate but exists as fine particles.
Those in which silver is reduced to fine particles
according to the present invention are pale yellow, whereas
the conventional ones become dark brown, thus the fibers and
the resins obtained by the present invention are advantageous
in this aspect.
The antimicrobial CDFR having silver sulfonate and the
pale yellow CDFR with fine silver particles adhered thereto
according to the present invention can be dyed with a
cationic dye in a suitable color tone by a known method.
Otherwise, the CDFR may be dyed with a cationic dye by the
conventional method at first, and then antimicrobial
properties can be provided thereto according to the method of
the present invention. Furthermore, the ant~imicrobial
properties can be provided according to the present invention
simultaneously with the dyeing using a cationic dye from
which halogen ions contained have been removed carefully.
Since the antimicrobial CDFR of the present invention
exhibits highly antimicrobial effects, in spite of a markedly
low content of silver, it is sufficient to use a small amount
of silver, and still does not adversely affect human body.
The antimicrobial CDFR of the present invention can be
utilized as an antimicrobial material in any place which has
a possibility to be contaminated with harmful microorganisms.
For example, as for the antimicrobial PAN, microbially clean
state can be maintained by making a bath mat, a toilet mat, a
toilet seat cover, a carpet, a mop, an air filter, a towel,
-- 13 ~ ~ ~ r
and a dish towel. The antimicrobial PAN may be used further
as work gloves or work clothings in food processing or
production. As for the antimicrobial CDPET, it can be used
in, for example, a white overall for the operation, a curtain
in hospital, a bed, a sofa, a pillow cover or a backing of a
slipper equipped in hospital, or a diaper cover, a sanitary
tampon and the like.
The antimicrobial CDFR of the present invention may be
used alone or used together with other fibers as mixed or
union fabric of a cloth, a knitted product, or a nonwoven
material.
Best Mode for Carryina Out the Invention
Now, the present invention will be described more
precisely with reference to the working examples. The
present invention, however, should not be limited to these
examples. The test for antimicrobial activity was carried
out by adhering bacterium, Staphylococcus aureus or
Klebsiella pneumoniae, having been suspended in a standard
bouillon medium, to a test strip, maintaininq it at 37C for
18 hours, and then counting the number of the living
bacterium on the test strip. The test for washing fastness
was carried out by measuring the antimicrobial effect of a
test strip which was subjected to the procedure according to
JIS L 0217 103 repeatedly thirty times, and measuring the
amount of remaining silver by atomic absorption spectrometry.
- 14 - s~
Example Al
100 parts by weight of Cashmilon (PAN available from
Asahi Kasei Co., Ltd.) was soaked in 3000 parts by weight of
water containing 0.126 part by weight of silver nitrate. It
was heated to a boil, and maintained in the boiling state for
30 minutes. Then the heating was stopped, and it was left
standing until it cooled down to 50C, after which Cashmilon
was taken out. It was thoroughly washed with water and then
dried, to obtain a Cashmilon having silver-sulfonate gxoup.
Evaluation of Antimicrobial Activity
0.2 g of the treated cloth obtained in the above-
mentioned manner was sampled, then 0.2 ml of a standard
bouillon suspension of Staphylococcus aureus ATCC 6538P (the
number of bacterium; 8 x 105/ml) was applied thereon. This
was maintained at 37C for 18 hours, and then it was
extracted with 20 ml of physiological saline buffer
containing phosphate. The extract was inoculated into a
standard agar medium, and the number of bacterium was
counted. As a result, the extract from the treated cloth
according to the present invention was found to contain 18
bacteri.um/ml. In contrast, the extract from an untreated
control cloth not containing silver was found to contain 9 x
103 bacterium/ml.
Example A2
- 15 - ~ ~
A testing cloth (a treated cloth) was obtained by
following the procedure of Example A1, except that 100 parts
by weight of Toraylon (PAN available from Toray Co., Ltd.)
instead of Cashmilon and 0.063 part by weight of silver
nitrate instead of 0.126 part by weight were used. As a
result of carrying out antimicrobial test in the manner of
Example A1 using the resultant Toraylon, 35 bacterium/ml were
detected from the extract and 7 x 103 bacterium/ml were
detected from the extract from an untreated cloth not
containing silver.
Examples A3 and A4
Testing cloths (treated cloths) were obtained by
following the procedure of Example A1, except that the
amounts of silver nitrate were changed to 0.032 part by
weight, and 0.008 part by weight respectively, and the test
was carried out in a similar manner.
The results of Example A1 to A4 are shown in Table A1.
- 16 - ~ . 3 J7
Table A1
~mount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry) for 18 hrs
A1805 ppm 18 bacterium/ml
_
A2397 ppm 35 bacterium/ml
A3195 ppm 25 bacterium/ml
_
A4 52 ppm 93 bacterium/ml
Examples A5 to A8
100 parts by weight of the cloths obtained in Examples
A1 to A4 were respectively soaked in 500 parts by weight of
water in which 0.5 part by weight of sodium boron hydride had
been suspended, and then heated to a boil for 30 minutes.
After washing with water and drying, were obtained cloths to
which silver was adhered as metallic silver by reducing
silver ion. Each of them was evaluated in a similar manner
to Example A1. The results are shown in Table A2.
'
Table A2
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry~ for 18 hrs
A5 (Al) 780 ppm8 bacterium/ml
A6 (A2) 367 ppm25 bacterium~ml
A7 (A3) 188 ppm34 bacterium/ml
A8 (A4) 48 ppm51 bacterium/ml
Examples A9 to A12
The cloths to which silver was adhered or bonded, and
which were obtained in Examples Al, A3, A5, and A7, were
washed repeatedly thirty times according to the procedure of
JIS L 0217 103. Respectively, the amount of silver remaining
and the results of the antimicrobial activity tests carried
out in the same manner as in Example Al are shown in Table
~3.
- 18 -
Table A3
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry) for 18 hrs
A9 (A1) 713 ppm 25 bacterium/ml
AlO(A3) 168 ppm 61 bacterium/ml
All(A5) 699 ppm 38 bacterium/ml
A12(A7) 162 ppm 30 bacterium/ml
Examples A13 to A16
The antimicrobial activity tests were carried out in the
same manner as in Example A1, except that 0.2 ml of a
standard bouillon suspension of Klebsiella pneumoniae ATCC
4352 (number of bacterium: 9 x 105/ml) in place of
Staphylococcus aureus was applied on each of the cloths to
which silver was adhered or bonded and which were obtained in
Examples A1, A3, A5 and A7. The results are shown in Table
A4. The extract from the untreated control cloth not
containing silver contained 1 x 104 bacterium/ml.
- 19 --
Table A4
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry) for 18 hrs
A13~A1) 805 ppm 25 bacterium/ml
A14(A3) 195 ppm 31 bacterium/ml
A15(A5) 780 ppm 42 bacterium/ml
A16~A7) 188 ppm 38 bacterium/ml
Example A17
The antimicrobial activity test was examined for the
testing strip obtained in the same manner as in Example A1
except that 0.124 part by weight of silver lactate was used
in place of silver nitrate. The results obtained were
substantially the same as those of Example A1.
Examples A1~ and A19
A testing cloth was obtained in the same manner as in
Example A5, except that 2.5 parts by weight of hydroxyl amine
or 2.5 parts by weight of hydrazine was used in place of
sodium boron hydride, and the antimicrobial activity test was
examined. In each case, the results obtained were
substantially the same as those of Example A5.
Example A20
- 20 . d ~
100 parts by weight of Exlan (PAN available from Nihon
Exlan Co., Ltd.) having sulfonate group was soaked in 2,500
parts by weight of an aqueous 500 ppm acetic acid solution
(pH = 3.4) containing 0.063 part by weight of silver nitrate,
and heated to 100C with stirring. After stirring at 120C
for one hour, it was allowed to cool, thoroughly washed with
water, dried, to obtain a polyacrylonitrile cloth having
silver sulfonate. The content of silver in this
polyacrylonitrile cloth was 368 ppm.
Example A21
A polyacrylonitrile cloth having silver sulfonate was
obtained by following the procedure of Example A20, except
that treatment was performed using 2,500 parts by weight of
water (pH = 6.5) containing 0.063 part by weight of silver
nitrate instead of the aqueous 500 ppm acetic acid solution
containing 0.063 part by weight of silver nitrate. The
content of silver in this polyacrylonitrile cloth was 374
ppm.
Both of the polyacrylonitrile cloths obtained in Example
A20 and in Example A21 exhibited antimicrobial effects
similar to those of Examples A1 to A4.
Example A22
Color difference between the polyacrylonitrile cloth
obtained in Example A20 or in Example A21 and an untreated
:
- 21 ~ F~1
polyacrylonitrile cloth was measured by the use of a color
difference meter. The results are given in Table A5.
Table A5
Acetic acid
Concentration pH aL aa ab
Example A20500 3.4 -0.10 0.11 0.09
Example A216.5 -2 02 0 98 3 27
In Table A5 given above, aL, ~a, and ~b represent
lightness difference, hue difference, and saturation
difference between the treated cloth and the untreated cloth,
respectively.
It is clear from the results shown in Table A5 that
though the color tone of the polyacrylonitrile cloth obtained
in Example A20 is little different from that of the untreated
polyacrylonitrile cloth, the polyacrylonitrile cloth obtained
in Example A21 decreases in lightness and has a higher value
both for aa, and ab, in comparison with those of the
untreated polyacrylonitrile cloth. An increase in aa means
that the cloth becomes tinted with red, and an increase of ab
means that the cloth becomes tinted with yellow. The
difference between the results obtained in Example A20 and in
Example A21 is due to the pH value of the treating solution.
22 r~ 2 : ~ ~
Especially when coloration causes a problem in such a case
where a white polyacrylonitrile cloth is desired, an
antimicrobial polyacrylonitrile cloth without any color tone
variation can be obtained by conducting the reaction in an
acidic aqueous solution by adjusting the pH value.
Example A23
120 parts by weight of Toraylon ~PAN available from
Toray Co., Ltd.) having sulfonate group was soaked in 3,600
parts by weight of water in which 0.24 part by weight of
silver nitrate was dissolved. It was then gradually heated
to a boil, maintained for 30 minutes, and then the Toraylon
was taken out and washed with water.
Subsequently, 0.4 part of a cationic dye, Kayacryl light
blue 4GSL, was dissolved in 3,000 parts by weight of water.
In this was again soaked the Toraylon treated with the
aqueous silver nitrate solution in the above step. After the
addition of 10 parts by weight of 10% acetic acid, it was
heated to a boil. After maintaining 20 minutes, it was
allowed to cool down to 50C or less gradually, after which
the Toraylon was taken out, thoroughly washed with water, and
then dried to obtain a blue dyed Toraylon having silver-
sulfonate group.
Evaluation of Antimicrobial Activity
0.2 g of a test strip was sampled from the cloth
obtained in the above-mentioned manner, and 0.2 ml of a
standard bouillon suspension of ~lebsiella pneumoniae
ATCC4352 (the number of bacteriumi 9 x 105/ml) was applied
thereon. This was maintained at 37C for 18 hours, and then
it was extracted with 20 ml of physiological saline buffer
containing phosphate. As a result, the extract from the
treated cloth according to the present invention was found to
contain 43 bacterium/ml. In contrast, the extract from an
untreated control cloth not containing silver was found to
contain 1 x 104 bacterium/ml.
Example A24
120 parts by weight of Toraylon (PAN available from
Toray Co., Ltd.) having sulfonate group was dyed red at 100C
by the use of 0.3 part of Kayacryl red GL. The bath ratio
was 1 : 30.
Then, the red dyed cloth was soaked in 1200 parts by
weight of water containing 0.2 part by weight of silver
nitrate. It was then gradually heated, and boiled for 30
minutes. Thereafter, it was thoroughly washed with boiling
water.
Further, it was incorporated into 1200 parts by weight
of 0.4% hydroxylamine sulfate solution, and boiled for 30
minutes. After the liquid cooled down to 50C or below, the
treated cloth was taken out, thoroughly washed with water,
and then dried.
When the antimicrobial activity test of the red cloth
thus obtained, to which adhered fine silver particles, was
- 24 ~ .Y~
carried out using Klebsiella pneumoniae, it had a strong
activity.
Example A25
The treatment of Example A1 was repeated except that
particles of polyacrylonitrile having sulfonate group were
treated instead of Cashmilon in Example A1. The treated
polyacrylonitrile particle exhibited antimicrobial effect
similar to those of Example A1.
Example B1
100 parts by weight of a cationic dye dyeable type
polyester cloth having sulfonate group (standard dyeing
temperature 120C) was soaked in 3000 parts by weight of
boiling water containing 0.18 part by weight of silver
nitrate, and maintained at this state for 30 minutes. After
being cooled, the treated cloth was taken out, thoroughly
washed with water, and dried to obtain a polyester cloth
having silver sulfonate group. When the silver content was
measured by atomic absorption spectrometry method, it was
found to contain 840 ppm of silver.
Evaluation of Antimicrobial Activity
0.2 g of the cloth obtained in the above-mentioned
manner was sampled and 0.2 ml of a standard bouillon
suspension of Staphylococcus aureus ATCC 6583P (the number of
bacterium; 8 x 105/ml) was applied thereto. This was
maintained at 37C for 18 hours, and then it was extracted
- 25 ~
with 20 ml of physiological saline buffer containing
phosphate. The extract was inoculated into a standard agar
medium, and the number of bacterium was counted. As a
result, the extract from the treated cloth according to the
present invention was found to contain 120 bacterium/ml. In
contrast, the extract from an untreated control cloth not
containing silver was found to contain 6 x 108 bacterium/ml.
Examples B2 to B4
Treated cloths respectively containing specific amount
of silver were obtained by following the procedure of Example
B1, except that 0.09 part by weight, 0.045 part by weight,
and 0.01 part by weight of silver nitrate were respectively
used instead of 0.18 part by weight of silver nitrate. They
were evaluated in a similar manner as in Example B1. The
results are shown in Table B1.
- 26 -
Table Bl
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry) fo- 18 hrs
Bl840 ppm120 bacterium/ml
B2414 ppm95 bacterium/ml
'.. , _
B3 193 ppm 145 bacterium/ml
B4 67 ppm 135 bacterium/ml
Examples B5 to B8
100 parts by weight of the cloths obtained in Examples
Bl to B4 were respectively soaked in 500 parts by weight of
aqueous 0.5% hydroxylamine solution, and then boiled for 30
minutes. Subsequent washing with water and drying gave
r cloths to which adhered silver as metallic silver by reducing
silver ion. Each of them was evaluated in a similar manner
as in Example Bl. The results are shown in Table B2.
- 27 ~t _~
Table B2
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomlc after treatment at 37C
absorption spectrometry) for 18 hrs
B5 (B1)823 ppm 85 bacterium/ml
B6 (B2)400 ppm 120 bacterium/ml
~7 (B3)195 ppm 98 bacterium/ml
B8 (B4)57 ppm 160 bacterium/ml
Examples B9 to B12
The cloths to which silver was adhered or bonded, and
which were obtained in Examples B1, B3, B5, and B7, were
washed repeatedly thirty times according to the procedure of
JIS L 0217 103. The amounts of the remaining silver and the
results of the antimicrobial activity test in the same manner
as in Example B1 are shown in Table B3.
- ~8 - 5;J `~
Table B3
.
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry) for 18 hrs
B9 (Bl) 780 ppm115 bacterium/ml
BlO(B3) 177 ppm156 bacterium/ml
Bll(B5) 764 ppm98 bacterium/ml
11:2l~7) 180 ppm 135 bacterium/ml
Examples B13 to B16
The antimicrobial activity tests were carried out in the
same manner as in Example B1, except that 0.2 ml of a
standard bouillon suspension of Klebsiella pneumoniae ATCC
4352 (number of bacterium: 9 x 105/ml) in place of
Staphylococcus aureus was applied on each of the treated
cloths obtained in Examples B1, B3, B5 and B7. The extract
from the untreated control cloth not containing silver
contained 8 x 10 bacterium/ml. The results are shown in
Table B4.
- 29 ~ ~ t i
Table B4
Amount of Silver on The number of Bacterium
Example Treated Cloth (atomic after treatment at 37C
absorption spectrometry) for 18 hrs
B13(B1) 840 ppm 93 bacterium/ml
B14(B3) 193 ppm 150 bacterium/ml
B15(B5) 823 ppm 100 bacterium/ml
B16(B7) 195 ppm 142 bacterium/ml
, i
Example B17
The antimicrobial activity test was carried out on the
strip obtained in the same manner as in Example B1 except
that 0.17 part by weight of silver lactate was used in place
of silver nitrate in Example B1. The results obtained were
substantially the same as those of Example B1.
Examples B18 and B19
A test cloth was obtained in the same manner as in
Example B5, except that 500 parts by weight of an aqueous
0.5% hydrazine solution or 500 parts by weight of 0.5% sodium
boron hydride suspension was used in place of hydroxylamine
in Example B5, and the antimicrobial activity test was
carried out. In each case, the results obtained were
substantially the same as those of Example B5.
~-
- 30 -
Example B20
100 parts by weight of a cationic dye dyeable type
polyester having sulfonate group (a standard dyeing
temperature: 105C) was soaked in 2,500 parts by weight of
water containing 0.05 part of silver nitrate, and heated to
boil with stirring. After stirring for another 20 minutes,
it was allowed to cool, thoroughly washed with water, and
dried to obtain a polyester cloth having silver sulfonate
group. When the content of silver in this polyester cloth
was measured by atomic absorption spectrometry, it was found
to contain 301 ppm of silver. The silver content in the
polyester cloth after washing 30 times as in Example B9 was
290 ppm. As a result of carrying out the evaluation of
antimicrobial activity on the unwashed polyester cloth and
the polyester cloth after washing 30 times, the extract from
the unwashed cloth was found to contain 135 bacterium/ml and
the extract from the polyester cloth after washing 30 times
was found to contain 118 bacterium/ml, while the untreated
polyester cloth for control which did not contain silver was
found to contain 7 x 108 bacterium/ml.
Example B21
100 parts by weight of a cationic dye dyeable type
polyester ~a standard dyeing temperature: 120C) was soaked
in 1,500 parts by weight of an aqueous 100 ppm acetic acid
solution (pH = 3.8) containing 0.063 parts by weight of
silver nitrate, and heated to 120C under pressure with
stirring. After stirring at 120C for 1 hour, it was allowed
to cool, thoroughly washed with water, and dried to obtain a
polyester cloth having silver sulfonate group. The content
of silver in this polyester cloth was 344 ppm.
Example B22
A polyester cloth having silver sulfonate group was
obtained by following the procedure of Example B21, except
that treatment was performed using 1,500 parts by weight of
water (pH = 6.5) containing 0.063 part by weight of silver
nitrate instead of 1,500 parts by weight of aqueous 100 ppm
acetic acid solution containing 0.063 part by weight of
silver nitrate. The content of silver in this polyester
cloth was 354 ppm.
Both of the polyester cloths obtained in Example B21 and
in Example B22 exhibited antimicrobial effects similar to
those of Example B20.
Example B23
Color difference between the polyester cloth obtained in
Example B21 or in Example B22 and an untreated polyester
cloth was measured by the use of a color difference meter.
The results are given in Table B5.
- 32 -
Table B5
Acetic acid
Concentration pH AL ~a ~b
Example B21100 3.8 -0.26 0.31 0.17
,
Example B226 5 -2 68 0.70 3.96
In Table B5, ~L, aa, and ~b represent lightness
difference, hue difference, and saturation difference between
the treated cloth and the untreated cloth, respectively.
It is clear from the results shown in Table B5 that
though the color tone of the polyester cloth obtained in
Example B21 is little different from that of the untreated
polyester cloth, the polyester cloth obtained in Example B22
decreases in lightness and has a higher value both for ~a,
and ~b, in comparison with those of the untreated polyester
cloth. The difference between the results obtained in
Example B21 and in E~ample B22 is due to the pH value of the
treating solution. Especially when coloration causes a
problem in such a case where a white polyester cloth is
desired, an antimicrobial polyester cloth without any color
tone variation can be obtained by conducting the reaction in
an acidic aqueous solution by adjusting the pH value.
Example B24
- 33 - d ' . `-~ ;J ~
120 parts by weight of a cationic dye dyeable polyester
jersey having sulfonate group was first dyed red at 120C
using 0.3 part by weight of a cationic dye Kayacryl Red GL.
The bath ratio was 1 : 30.
Then, the red dyed cloth was soaked in 1,200 parts by
weight of water containing 0.2 part by weight of silver
nitrate, and gradually heated to a boil, and maintained for
30 minutes. Thereafter, it was thoroughly washed with
boiling water and then dried to obtain a polyester having
silver-sulfonate group.
The polyester thus treated also had a high antimicrobial
activity against Staphylococcus aureus and Klebsiella
pneumoniae .
Example B25
35 parts by weight of the cationic dye dyeable polyester
with fine particles of silver adhered thereon obtained in
Example B5 was soaked in 400 parts by weight of water in
which 0.07 part by weight of a cationic dye, Kayacryl blue
4GSL, had been dissolved. It was heated to 120C in an
autoclave, and maintained for 40 minutes to carry out dyeing.
After cooling, the dyed cloth was taken out, and thoroughly
washed with water to obtain a blue dyed polyester cloth. The
antimicrobial activity was retained.
Example B26
2 ~
,.
The treatment of Example B1 was carried out except that
a polyester resin particle having sulfonate group was used
instead of the cationic dye dyeable polyester cloth in
Example Bl. The resultant polyester resin particle exhibited
antimicrobial effects similar to those of Example B1.
Industrial Applicability
The antimicrobial CDFR of the present invention, in
spite of a smaller amount of silver to be adhered or bonded
than that of the conventional one, exhibits strong
antimicrobial effects, and excels in wash fastness. The
antimicrobial CDFR of the present invention also is very
safe, and when incinerating it, it is free from generating
any toxic substance derived from the substance used for
providing antimicrobial activity. Further, the antimicrobial
CDFR of the present invention has a markedly low stimulation
on skin, thus it can also suitably be used in such an
application as bringing it into contact with skin such as
clothes.
Furthermore, according to the present invention,
antimicrobial properties can be easily and economically
provided to PAN and CDPET having sulfonic group and/or
sulfonate group or fibers mixed or combined with, PAN or
CDPET. There is, in the present invention, substantially no
problem of coloration of the fiber or resin due to adhering
or bonding of silver.
