U.S. patent application number 14/889729 was filed with the patent office on 2016-04-21 for antibacterial glass.
The applicant listed for this patent is KOA GLASS CO., LTD.. Invention is credited to Yoshinao KOBAYASHI, Kunihiko NEMOTO.
Application Number | 20160106109 14/889729 |
Document ID | / |
Family ID | 52143462 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160106109 |
Kind Code |
A1 |
KOBAYASHI; Yoshinao ; et
al. |
April 21, 2016 |
ANTIBACTERIAL GLASS
Abstract
Provided is an antimicrobial glass which can be accommodated in
a narrow accommodation space of an antimicrobial water unit for
supplying antimicrobial water to a washing tub of a washing
machine, and also can effectively suppress an occurrence of black
mold or the like in a washing tub and can effectively protect a
subject for washing against microbes while suppressing the
coloration of the subject. As an antimicrobial glass for exhibiting
an antimicrobial effect by releasing silver ions when brought into
direct contact with water, when the total amount is 100% by weight,
the content of Ag.sub.2O has a value within the range of above 5%
by weight but less than 10% by weight, the content of
P.sub.2O.sub.5 and CaO has a value within a predetermined range,
the content of ZnO has a value of below 10% by weight, the content
of K.sub.2O, Al.sub.2O.sub.3, and MgO has a value within a
predetermined range, and the antimicrobial glass has a tablet shape
with a maximum diameter value in a predetermined range.
Inventors: |
KOBAYASHI; Yoshinao;
(Edogawa-ku, Tokyo, JP) ; NEMOTO; Kunihiko;
(Edogawa-ku, Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOA GLASS CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
52143462 |
Appl. No.: |
14/889729 |
Filed: |
May 27, 2014 |
PCT Filed: |
May 27, 2014 |
PCT NO: |
PCT/JP2014/063940 |
371 Date: |
November 6, 2015 |
Current U.S.
Class: |
424/408 ;
424/618 |
Current CPC
Class: |
A01N 59/26 20130101;
A01N 59/16 20130101; A01N 59/06 20130101; C03C 2204/02 20130101;
C03C 3/17 20130101; C02F 2307/12 20130101; A01N 59/16 20130101;
C03C 4/0007 20130101; A01N 59/26 20130101; Y02W 10/37 20150501;
C02F 1/50 20130101; A01N 59/06 20130101; A61L 2/16 20130101; D06F
39/024 20130101; C02F 1/688 20130101; D06F 39/00 20130101; C02F
1/505 20130101; C02F 2103/002 20130101; A01N 25/34 20130101; C02F
2101/30 20130101; C02F 2303/04 20130101; C03C 3/19 20130101; A01N
59/06 20130101; A01N 59/16 20130101; A01N 59/00 20130101; A01N
59/26 20130101; A01N 59/00 20130101; A01N 25/34 20130101; A01N
59/26 20130101; A01N 59/16 20130101; A01N 25/34 20130101; D06F
35/008 20130101; A01N 59/00 20130101 |
International
Class: |
A01N 59/16 20060101
A01N059/16; D06F 39/00 20060101 D06F039/00; A01N 25/34 20060101
A01N025/34; C02F 1/50 20060101 C02F001/50 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 2, 2013 |
JP |
2013-138575 |
Claims
1. An antimicrobial glass for exhibiting an antimicrobial effect by
releasing silver ions when brought into direct contact with water,
wherein it contains Ag.sub.2O, P.sub.2O.sub.5, CaO, ZnO, K.sub.2O,
Al.sub.2O.sub.3, and MgO as a raw material, and when the total
amount is 100% by weight, the content of Ag.sub.2O has a value
within the range of above 5% by weight but less than 10% by weight,
the content of P.sub.2O.sub.5 has a value within the range of 55 to
75% by weight, the content of CaO has a value within the range of 1
to 10% by weight, the content of ZnO has a value of below 10% by
weight, the content of K.sub.2O has a value within the range of 5
to 20% by weight, the content of Al.sub.2O.sub.3 has a value within
the range of 1 to 10% by weight, and the content of MgO has a value
within the range of 5 to 20% by weight, and the antimicrobial glass
has a tablet shape with a maximum diameter value within the range
of 5 to 20 mm.
2. The antimicrobial glass according to claim 1, wherein the
specific surface area of the antimicrobial glass has a value within
the range of 0.1 to 5 cm.sup.2/g.
3. The antimicrobial glass according to claim 1, wherein the silver
ion elution amount of the antimicrobial glass which is measured
according to the following measurement conditions has a value
within the range of 0.025 to 0.1 mg/(g1 liter24 Hrs30.degree. C.)
which is measured in accordance with the following measurement
conditions: 30 g of the antimicrobial glass as a subject for
measurement is immersed in 1 liter of purified water (30.degree.
C., pH 6.5) and kept in a closed system for 24 hours with the
temperature maintained followed by measurement.
4. The antimicrobial glass according to claim 1, wherein C2/C1 has
a value of 0.4 or more when the content of ZnO is C1 (% by weight)
and the content of Al.sub.2O.sub.3 is C2 (% by weight).
5. The antimicrobial glass according to claim 1, wherein it is
accommodated inside a coated member provided with an opening for
passing water therethrough.
6. The antimicrobial glass according to claim 5, wherein it is
accommodated, together with a non-antimicrobial glass, inside a
coated member.
7. The antimicrobial glass according to claim 1, wherein it is an
antimicrobial glass for a washing machine accommodated in an
antimicrobial water unit for supplying antimicrobial water to a
washing tub of a washing machine.
Description
TECHNICAL FIELD
[0001] The present invention relates to an antimicrobial glass, in
particular, an antimicrobial glass which can be accommodated in a
narrow accommodation space of an antimicrobial water unit for
supplying antimicrobial water to a washing tub of a washing
machine, and can effectively suppress an occurrence of black mold
or the like in a washing tub and can effectively protect a subject
for washing against microbes while suppressing the coloration.
BACKGROUND ART
[0002] Conventionally, for preventing propagation of bacteria or
mold in water stored in a water storage tank or a drain pan of an
air conditioner or the like, an antimicrobial glass exhibiting an
antimicrobial effect by releasing silver ions into water when
brought into direct contact with water has been broadly used.
[0003] Furthermore, for the antimicrobial glass used for such
application, a predetermined elution amount of silver ions needs to
be maintained over a long period of time, and thus various
modifications, for example, the composition or size of the
antimicrobial glass is modified to a predetermined range or a pH
fluctuation of water is suppressed by using in combination plural
antimicrobial glasses with different properties, have been made to
satisfy such needs (for example, see Patent Document 1 and Patent
Document 2).
[0004] Specifically, disclosed in Patent Document 1 is, as a
soluble glass containing at least one element selected from
metallic ions of Ag.sup.+, Cu.sup.+, Cu.sup.2+, and Zn.sup.2+, a
glass water treatment material characterized in that it has right
hexahedral, cubic, flat, or spherical three-dimensional shape and
its largest diameter is 10 mm or more and its composition has
weight ratios of (RO+R.sub.2O)/P.sub.2O.sub.5=0.4 to 1.2 and
R.sub.2O/(RO+R.sub.2O.sub.3)=0 to 10, the dissolution speed (A) at
an initial stage (a period corresponding to initial 20% of the time
period from start of dissolution to dissolution of the entire
amount, the same shall apply hereinafter) and the dissolution speed
(B) at a final stage (on contrary to the initial period, it
indicates a period corresponding to final 20%, the same shall apply
hereinafter) have a relationship of B/A.gtoreq.1/3, and the content
of the metallic ions is 0.005 to 5% by weight.
[0005] Furthermore, disclosed in Patent Document 2 is a mixed
antimicrobial glass for an air conditioning system, exhibiting an
antimicrobial effect by releasing silver ions therefrom in the air
conditioning, including an antimicrobial glass exhibiting an
alkaline property when dissolved and an antimicrobial glass
exhibiting an acid property when dissolved, an elution amount of
silver ions, which is measured under a prescribed measurement
condition, of the antimicrobial glass exhibiting an alkaline
property, and an elution amount of silver ions, which is measured
under a prescribed measurement condition, of the antimicrobial
glass exhibiting an acid property are respectively values within
the range of 0.005 to 1 mg/(g1 liter24 Hrs30.degree. C.), a
blending amount of the antimicrobial glass exhibiting an alkaline
property to 100 parts by weight of the antimicrobial glass
exhibiting an acid property is a value within the range of 10 to
120 parts by weight, and the total elution amount of silver ions
measured under the prescribed measurement condition is a value
within the range of 0.01 to 5 mg/(g1 liter24 Hrs30.degree. C.)
[0006] In Patent Document 2, there is also a description suggesting
that the antimicrobial glass exhibiting an acid property when
dissolved preferably has the composition in which it contains
Ag.sub.2O, MgO, K.sub.2O, ZnO and P.sub.2O.sub.5 as a raw material,
and when the total amount is 100% by weight, the content of
Ag.sub.2O has a value within the range of above 5% by weight but
less than 10% by weight, the content of MgO has a value within the
range of 3 to 10% by weight, the content of K.sub.2O has a value
within the range of 5 to 20% by weight, the content of ZnO has a
value within the range of 10 to 25% by weight, and the content of
P.sub.2O.sub.5 has a value within the range of 55 to 75% by weight,
and when the total amount is less than 100% by weight, other glass
components (for example, alkali metal oxide, alkali earth metal
oxide, CeO.sub.2, Al.sub.2O.sub.3, CoO, or the like) are contained,
as a residual component, within the range of 0.1 to 37% by
weight.
CITATION LIST
Patent Document
[0007] Patent Document 1: JP 7-63701 A (Claims and the like)
[0008] Patent Document 2: JP 2012-7870 A (Claims and the like)
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0009] However, according to the glass water treatment material
described in Patent Document 1, the content of metal ions which
exhibit an antimicrobial effect is limited to 0.005 to 5% by
weight. As such, there is a problem that, in order to increase the
elution amount of metal ions, a large amount of the glass water
treatment material has to be added to water.
[0010] In particular, for supplying antimicrobial water to a
washing tub of a washing machine, it is required to protect a
subject for washing against microbes but also to prevent an
occurrence of black mold or the like in the washing tub.
[0011] Thus, it is required to elute, within a short period of
time, at least predetermined amount of metal ions to a large amount
of water, and to satisfy such requirement, it is necessary to use a
large amount of a glass water treatment material.
[0012] Meanwhile, for having a small size and an improved design of
a washing machine as a whole, an antimicrobial water unit for
supplying antimicrobial water to a washing tub of a washing machine
is configured to be very small. As such, there is a problem that it
is not possible to have a space enough for accommodating a large
amount of a glass water treatment material.
[0013] As such, the glass water treatment material described in
Patent Document 1 has a problem that it is difficult to be used for
an application for supplying antimicrobial water to a washing tub
of a washing machine.
[0014] Furthermore, in the antimicrobial glass exhibiting an acidic
property when dissolved as described in Patent Document 2, the
content of Ag.sub.2O as a basis of silver ion is more than 5% by
weight but less than 10% by weight, and thus the elution amount of
silver ions can be increased without adding a large amount of an
antimicrobial glass to water, and also it is possible to apply the
antimicrobial glass for supplying antimicrobial water to a washing
tub of a washing machine.
[0015] However, because the antimicrobial glass exhibiting an
acidic property when dissolved as described in Patent Document 2 is
supposed to be used in combination with an antimicrobial glass
exhibiting an alkaline property when dissolved, if it is used
singly, the dissolution speed becomes excessively high, and thus
there is a problem that it is difficult to maintain a predetermined
elution amount of silver ions over a long period of time.
[0016] Furthermore, as the dissolution speed becomes excessively
high, the elution amount of silver ions also excessively increases
so that there is also a problem that coloration of a subject for
washing is easily caused by excessive silver ions.
[0017] Accordingly, the inventors of the present invention
conducted intensive studies in view of the aforementioned problems.
As a result, it was found that, when the composition of an
antimicrobial glass which releases silver ions when brought into
direct contact with water is set to a predetermined composition and
the shape and maximum diameter of the glass are adjusted to be in a
predetermined range, it is possible to obtain an antimicrobial
glass which can stably maintain a predetermined elution amount of
silver ions over a long period of time, even if it is a compact
amount. The present invention is completed accordingly.
[0018] Namely, an object of the present invention is, in
particular, an antimicrobial glass which can be accommodated in a
narrow accommodation space in an antimicrobial water unit for
supplying antimicrobial water to a washing tub of a washing
machine, can effectively suppress an occurrence of black mold or
the like in a washing tub, and can effectively protect a subject
for washing against microbes while suppressing coloration of the
subject.
Means for Solving Problem
[0019] According to the antimicrobial glass of the present
invention, an antimicrobial glass for exhibiting an antimicrobial
effect by releasing silver ions when brought into direct contact
with water, in which it contains Ag.sub.2O, P.sub.2O.sub.5, CaO,
ZnO, K.sub.2O, Al.sub.2O.sub.3, and MgO as a raw material, and when
the total amount is 100% by weight, the content of Ag.sub.2O has a
value within the range of above 5% by weight but less than 10% by
weight, the content of P.sub.2O.sub.5 has a value within the range
of 55 to 75% by weight, the content of CaO has a value within the
range of 1 to 10% by weight, the content of ZnO has a value of
below 10% by weight, the content of K.sub.2O has a value within the
range of 5 to 20% by weight, the content of Al.sub.2O.sub.3 has a
value within the range of 1 to 10% by weight, and the content of
MgO has a value within the range of 5 to 20% by weight, and the
antimicrobial glass has a tablet shape with a maximum diameter
value within the range of 5 to 20 mm, is provided to solve the
aforementioned problems.
[0020] Namely, according to the antimicrobial glass of the present
invention, the composition of the glass is set to a predetermined
composition and the shape and maximum diameter of the glass are
adjusted to be in a predetermined range, and thus it is possible to
stably maintain a predetermined elution amount of silver ions over
a long period of time, for example, ten years or longer, even if it
is a compact amount.
[0021] Thus, according to the antimicrobial glass of the present
invention, in particular, it is possible to have accommodation in a
narrow accommodation space in an antimicrobial water unit for
supplying antimicrobial water to a washing tub of a washing
machine, effective suppression of an occurrence of black mold or
the like in a washing tub, and effective protection of a subject
for washing while suppressing coloration of the subject.
[0022] Furthermore, for configuring the antimicrobial glass of the
present invention, it is preferable that the specific surface area
of the antimicrobial glass has a value within the range of 0.1 to 5
cm.sup.2/g.
[0023] By having this configuration, the predetermined amount of
silver ions can be more stably maintained over a long period of
time.
[0024] For configuring the antimicrobial glass of the present
invention, the silver ion elution amount measured for the
antimicrobial glass by the following measurement conditions
(hereinbelow, referred to as reference silver ion elution amount)
is preferably a value within the range of 0.025 to 0.1 mg/(g1
liter24 Hrs30.degree. C.)
[0025] Measurement Conditions
[0026] 30 g of the antimicrobial glass as a subject for measurement
is immersed in 1 liter of purified water (30.degree. C., pH 6.5)
and kept in a closed system for 24 hours with the temperature
maintained followed by measurement.
[0027] By having this configuration, a predetermined silver ion
elution amount can be more stably maintained over a long period of
time.
[0028] Furthermore, for configuring the antimicrobial glass of the
present invention, when the contents of the ZnO and Al.sub.2O.sub.3
are C1 (% by weight) and C2 (% by weight), respectively, the C2/C1
is preferably a value of 0.4 or more.
[0029] By having this configuration, a predetermined silver ion
elution amount can be more stably maintained over a long period of
time.
[0030] Furthermore, for configuring the antimicrobial glass of the
present invention, accommodation is preferably made inside a coated
member which is provided with an opening for passing water
therethrough,
[0031] By having this configuration, not only the handling is
improved but also the release caused by flowing water can be
prevented even when the antimicrobial glass is reduced to a small
size due to use for a long period of time.
[0032] Furthermore, for configuring the antimicrobial glass of the
present invention, accommodation is preferably made, together with
a non-antimicrobial glass, inside a coated member.
[0033] By having this configuration, adhesion between antimicrobial
glasses are prevented so that a predetermined silver ion elution
amount can be more stably maintained over a long period of
time.
[0034] Furthermore, for configuring the antimicrobial glass of the
present invention, it is preferably an antimicrobial glass for a
washing machine to be accommodated in an antimicrobial water unit
for supplying antimicrobial water to a washing tub of a washing
machine.
[0035] By having this configuration, not only the accommodation can
be made in a narrow accommodation space in an antimicrobial water
unit for supplying antimicrobial water to a washing tub of a
washing machine but also effective suppression of an occurrence of
black mold or the like in a washing tub and effective protection of
a subject for washing against microbes can be achieved while
suppressing coloration of the subject.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1(a) and FIG. 1(b) are drawings which are provided for
describing a location for installing an antimicrobial water unit in
a washing machine.
[0037] FIG. 2(a) and FIG. 2(b) are drawings which are provided for
describing the antimicrobial water unit.
[0038] FIG. 3 is a drawing provided for describing the relationship
between the ZnO content and a reference silver ion elution
amount.
[0039] FIG. 4 is a drawing provided for describing the relationship
between the ZnO content and a silver ion elution amount on Day 7
after immersion in purified water.
[0040] FIG. 5 is a drawing provided for describing the relationship
between the ZnO content and a silver ion elution amount on Day 14
after immersion in purified water.
[0041] FIG. 6 is a drawing provided for describing the relationship
between the ZnO content and the dissolution speed of an
antimicrobial glass over a long period of time.
[0042] FIG. 7 is a drawing provided for describing the relationship
between the contents of ZnO and Ag.sub.2O and the silver ion
concentration.
[0043] FIG. 8 is a drawing provided for describing the relationship
between the value of C2/C1 and a reference silver ion elution
amount.
[0044] FIG. 9 is a drawing provided for describing the relationship
between the value of C2/C1 and a silver ion elution amount on Day 7
after immersion.
[0045] FIG. 10 is a drawing provided for describing the
relationship between the value of C2/C1 and a silver ion elution
amount on Day 14 after immersion.
[0046] FIG. 11 is a photographic image provided for describing the
shape of an antimicrobial glass.
[0047] FIG. 12(a) and FIG. 12(b) are drawings which are provided
for describing a coated member.
[0048] FIG. 13 is a drawing provided for describing the shape of a
non-antimicrobial glass.
[0049] FIG. 14(a) and FIG. 14(b) are drawings which are provided
for describing the process for producing an antimicrobial
glass.
[0050] FIG. 15 is a photographic image provided for describing the
halo test result of Staphylococcus aureus.
[0051] FIG. 16 is a photographic image provided for describing the
halo test result of Escherichia coli.
[0052] FIG. 17 is a photographic image provided for describing the
halo test result of Aspergillus niger.
[0053] FIG. 18 is a photographic image provided for describing the
halo test result of Penicillium.
[0054] FIG. 19 is a photographic image provided for describing the
halo test result of black mold.
[0055] FIG. 20 is a photographic image provided for describing the
halo test result of Trichophyton.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0056] The embodiment of the present invention relates to an
antimicrobial glass for exhibiting an antimicrobial effect by
releasing silver ions when brought into direct contact with water,
characterized in that it contains Ag.sub.2O, P.sub.2O.sub.5, CaO,
ZnO, K.sub.2O, Al.sub.2O.sub.3, and MgO as a raw material, and when
the total amount is 100% by weight, the content of Ag.sub.2O has a
value within the range of above 5% by weight but 10% by weight or
less, the content of P.sub.2O.sub.5 has a value within the range of
55 to 75% by weight, the content of CaO has a value within the
range of 1 to 10% by weight, the content of ZnO has a value of
below 10% by weight, the content of K.sub.2O has a value within the
range of 5 to 20% by weight, the content of Al.sub.2O.sub.3 has a
value within the range of 1 to 10% by weight, and the content of
MgO has a value within the range of 5 to 20% by weight, and the
antimicrobial glass has a tablet shape with a maximum diameter
value within the range of 5 to 20 mm.
[0057] Hereinbelow, the antimicrobial glass as an embodiment of the
present invention is specifically described with appropriate
reference to the drawings.
[0058] Meanwhile, hereinbelow, the antimicrobial glass of the
present invention is described basically as an antimicrobial glass
for a washing machine. However, the antimicrobial glass of the
present invention is not limited to an antimicrobial glass for a
washing machine, and it is also applicable to, for example, a water
storage tank of equipment or products for keeping water for a
predetermined period, such as a water purifier, a humidifier, an
air cleaner, and a nozzle cleaner of a warm-water cleaning toilet
seat.
1. Application to Washing Machine
[0059] The antimicrobial glass of the present invention is
preferably an antimicrobial glass for a washing machine which is
installed in an antimicrobial water unit for supplying
antimicrobial water to a washing tub of a washing machine.
[0060] This is because, as described specifically hereinbelow, the
antimicrobial glass of the present invention has a predetermined
composition and the shape and maximum diameter that are within a
predetermined range, and thus it can stably maintain a
predetermined silver ion elution amount over a long period of time,
even if it is a compact amount.
[0061] As such, regarding the antimicrobial glass of the present
invention, it can be stored in a narrow accommodation space in an
antimicrobial water unit for supplying antimicrobial water to a
washing tub of a washing machine, can effectively suppress an
occurrence of black mold or the like in a washing tub, and can
effectively protect a subject for washing against microbes while
suppressing coloration of the subject.
[0062] Namely, the antimicrobial water unit in a drum type washing
machine 1a is installed, for example, on an inner wall side of a
circulating water path 4 for draining washing water inside a
washing tub 2, which is installed inside a cover 3, to outside,
purifying the washing water by collecting threads or the like in
the washing water, and circulating it back to the washing tub 2, as
shown in FIG. 1(a).
[0063] The circulating water path 4 is installed, from the
viewpoint of saving water, to recycle the washing water as much as
possible.
[0064] As the antimicrobial water unit is installed on the inner
wall side of the circulating water path 4, silver ions can be
constantly released to washing water circulating the circulating
water path 4 so that it becomes possible to supply efficiently the
antimicrobial water to the washing tub 2.
[0065] Furthermore, the antimicrobial water unit in a stand type
washing machine 1b can be installed, for example, on a backside of
a part 6 of the wall surface of the washing tub 2 as shown in FIG.
1(b).
[0066] Namely, in the case of filling washing water in the washing
tub 2, the washing water is filled to the backside of the wall
surface of the washing tub 2, via plural penetration holes that are
formed on the wall surface.
[0067] Accordingly, as the antimicrobial water unit is installed on
the backside of the part 6 of the wall surface of the washing tub
2, the silver ions can be constantly released into washing water
which passes through from the backside of the washing tub 2. As a
result, it becomes possible to supply efficiently the antimicrobial
water to the washing tub 2.
[0068] Furthermore, since the washing tub 2 repeats movement in a
forward rotational direction and a reverse rotational direction
during washing of a subject for washing, when the antimicrobial
water unit is installed on the backside of the part 6 of the wall
surface of the washing tub 2, the antimicrobial glass is stirred in
the washing water so that it becomes possible to supply more
efficiently the antimicrobial water to the washing tub 2.
[0069] Furthermore, as shown in FIG. 2(a) and FIG. 2(b), an
antimicrobial water unit 10 is preferably a plastic coated member
equipped with an opening 12 for pass-through of water and
preferably has a fixing hole 14 for fixing onto an inner wall of a
circulating water path or a backside of a wall surface of a washing
tub by means of a bolt or the like.
[0070] Furthermore, it can be preferably open and closed for
accommodating the antimicrobial glass inside the unit, and in that
case, it is preferably equipped with a hinge part 16 and a lock
part 18.
[0071] The volume of the antimicrobial water unit 10 is generally
10 to 30 cm.sup.2 from the viewpoint of having a space for
installation. Within such volume, 10 to 30 g of the antimicrobial
glass can be generally accommodated.
[0072] Meanwhile, for protecting a subject for washing against
microbes and efficiently suppressing an occurrence of black mold or
the like in a washing tub, it was confirmed that the silver ion
concentration needs to be a value of 1 ppb or more in washing water
in the washing tub. It was also confirmed that, to suppress the
coloration of a subject for washing, the silver ion concentration
needs to be a value of 90 ppb or less in washing water in the
washing tub.
[0073] It was also confirmed that, when the antimicrobial glass of
the present invention is applied to an antimicrobial water unit of
a commercially available washing machine, the silver ion
concentration in washing water can be stably maintained at a value
that is within the aforementioned range.
2. Composition
[0074] Regarding the composition of the antimicrobial glass of the
present invention, it is characterized in that it contains
Ag.sub.2O, P.sub.2O.sub.5, CaO, ZnO, K.sub.2O, Al.sub.2O.sub.3, and
MgO as a raw material, and when the total amount of the
antimicrobial glass is 100% by weight, the content of Ag.sub.2O has
a value within the range of above 5% by weight but 10% by weight or
less, the content of P.sub.2O.sub.5 has a value within the range of
55 to 75% by weight, the content of CaO has a value within the
range of 1 to 10% by weight, the content of ZnO has a value of
below 10% by weight, the content of K.sub.2O has a value within the
range of 5 to 20% by weight, the content of Al.sub.2O.sub.3 has a
value within the range of 1 to 10% by weight, and the content of
MgO has a value within the range of 5 to 20% by weight.
[0075] This is because, when the antimicrobial glass has the
aforementioned composition, not only the shape and maximum diameter
of an antimicrobial glass described below can be obtained but also
a certain silver ion elution amount can be maintained over a long
period of time even if it is a compact amount.
[0076] Hereinbelow, each component is separately and specifically
described.
[0077] (1) Ag.sub.2O
[0078] Ag.sub.2O as a raw material is a basic substance of silver
ions which are an antimicrobial component released at the time of
dissolution of glass components.
[0079] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of Ag.sub.2O as a
raw material has a value within the range of above 5% by weight but
10% by weight or less.
[0080] This is because, when the content of Ag.sub.2O has a value
of 5% by weight or less, the silver ion elution amount becomes
insufficient to yield a case in which protection of a subject for
washing against microbes is insufficient or the occurrence of black
mold or the like in a washing tub is not sufficiently suppressed.
In addition, when it is desired to increase an absolute amount of
an antimicrobial glass to be used for increasing the silver ion
elution amount, accommodation in a narrow space in an antimicrobial
water unit of a washing machine may be difficult to be achieved. On
the other hand, when the content of Ag.sub.2O has a value of above
10% by weight, it may be difficult to homogeneously disperse
Ag.sub.2O in an antimicrobial glass so that metal silver is
precipitated in the antimicrobial glass or metal silver remains in
a crucible during the process of producing an antimicrobial glass,
making it difficult to obtain an antimicrobial glass with
homogeneous quality.
[0081] As such, it is more preferable that the content of Ag.sub.2O
as a raw material has a value within the range of 5.5 to 8% by
weight. It is even more preferably a value within the range of 6 to
7% by weight.
[0082] (2) P.sub.2O.sub.5
[0083] P.sub.2O.sub.5 as a raw material basically functions as an
oxide for forming a network, and it also relates to improvement of
transparency or the property of homogeneous release of silver
ions.
[0084] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of P.sub.2O.sub.5 as
a raw material has a value within the range of 55 to 75% by
weight.
[0085] This is because, when the content of P.sub.2O.sub.5 has a
value of below 55% by weight, the solubility of the antimicrobial
glass is excessively lowered to yield an insufficient silver ion
elution amount, and thus there may be a case in which protection of
a subject for washing against microbes is insufficient or the
occurrence of black mold or the like in a washing tub is not
sufficiently suppressed. In addition, there may be a case in which
it is difficult to homogeneously disperse a large amount of
Ag.sub.2O, that is, above 5% by weight, in the antimicrobial glass
during the process of producing an antimicrobial glass. On the
other hand, when the content of P.sub.2O.sub.5 has a value of above
75% by weight, the solubility of an antimicrobial glass is
excessively increased so that not only it is difficult to maintain
stably the predetermined silver ion elution amount over a long
period of time but also the black coloration of a subject for
washing may easily occur due to presence of excessive silver
ions.
[0086] Meanwhile, it is believed that the black coloration based on
the presence of excessive silver ions is caused by decomposition of
silver chloride by light such as sunlight, in which the silver
chloride has been formed of silver ions and chlorides contained in
washing water.
[0087] As such, it is more preferable that the content of
P.sub.2O.sub.5 has a value within the range of 58 to 70% by weight.
It is even more preferably a value within the range of 60 to 65% by
weight.
[0088] (3) CaO
[0089] CaO as a raw material basically functions as an oxide for
modifying a network, and it also relates to improvement of
transparency or control of melting temperature.
[0090] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of CaO as a raw
material has a value within the range of 1 to 10% by weight.
[0091] This is because, when the content of CaO has a value of
below 1% by weight, the solubility of the antimicrobial glass is
excessively increased so that it is difficult to maintain stably a
predetermined silver ion elution amount over a long period of time,
and also black coloration of a subject for washing may easily occur
due to presence of excessive silver ions. On the other hand, when
the content of CaO has a value of above 10% by weight, the
solubility of an antimicrobial glass is excessively lowered to
yield a case in which protection of a subject for washing against
microbes is insufficient or the occurrence of black mold or the
like in a washing tub is not sufficiently suppressed.
[0092] As such, it is more preferable that the content of CaO has a
value within the range of 1.5 to 5% by weight. It is even more
preferably a value within the range of 2 to 3% by weight.
[0093] (4) ZnO
[0094] ZnO as a raw material is basically a substance for
maintaining stably the flexibility of an antimicrobial glass even
if the temperature changes.
[0095] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of ZnO as a raw
material has a value of below 10% by weight, that is, a value of
below 0 to 10% by weight (with the proviso that, 0% is excluded),
or 0% by weight.
[0096] This is because, when the content of ZnO has a value of 10%
by weight or more, the solubility of the antimicrobial glass is
excessively increased so that it is difficult to maintain stably a
predetermined silver ion elution amount over a long period of time,
and also black coloration of a subject for washing may easily occur
due to presence of excessive silver ions. On the other hand, when
the content of ZnO is excessively low, the solubility of an
antimicrobial glass can be slightly lowered so that the
antimicrobial property may be impaired.
[0097] As such, it is more preferable that the content of ZnO has a
value within the range of 4 to 9.5% by weight. It is even more
preferably a value within the range of 8 to 9.1% by weight.
[0098] Herein, by using FIGS. 3 to 5, the relationship between the
ZnO content and silver ion elution amount is described.
[0099] First, in FIG. 3, a characteristics curve in which the ZnO
content (% by weight) is plotted against the horizontal axis when
the total amount of the raw material of an antimicrobial glass is
100% by weight and the reference silver ion elution amount (mg/(g1
liter24 Hrs30.degree. C.)) is plotted against the vertical axis is
shown.
[0100] Meanwhile, the reference silver ion elution amount indicates
a silver ion elution amount which is measured after immersing 30 g
of the antimicrobial glass as a subject for measurement in 1 liter
of purified water (30.degree. C., pH 6.5) and keeping it in a
closed system for 24 hours with the temperature maintained.
[0101] Furthermore, as for the antimicrobial glass as a subject for
measurement, those produced in Examples 1 to 3 and Comparative
Examples 1 and 2 described below are used.
[0102] Namely, the antimicrobial glass in which the contents of
Ag.sub.2O and CoO are not modified while the content of ZnO is
modified with modification of other components at the same ratio as
the change in ZnO content is used.
[0103] As it is understood from the characteristics curve, it is
found that the silver ion elution amount (mg/(g1 liter24
Hrs30.degree. C.)) increases in accordance with an increase in the
ZnO content (% by weight).
[0104] More specifically, within a range in which the ZnO content
is a value within the range of below 10% by weight, it is found
that the reference silver ion elution amount stably maintains a
value of approximately 0.05 mg/(g1 liter24 Hrs30.degree. C.), but
when the ZnO content is 10% by weight or more, the reference silver
ion elution amount starts to increase rapidly, that is, when the
ZnO content is 14.05% by weight, it is increased to 0.1245 mg/(g1
liter24 Hrs30.degree. C.), and when the ZnO content is 19.05% by
weight, it is increased up to 0.255 mg/(g1 liter24 Hrs30.degree.
C.).
[0105] Furthermore, when the reference silver ion concentration of
the antimicrobial glass has a value of above 0.1 mg/(g1 liter24
Hrs30.degree. C.), it is found that the black coloration of a
subject for washing easily occurs when applied to an antimicrobial
water unit of a commercially available washing machine.
[0106] Thus, based on the characteristics curve shown in FIG. 3, it
is understood that, from the viewpoint of suppressing coloration of
a subject for washing, it is necessary that the content of ZnO as a
raw material is adjusted to a value of below 10% by weight.
[0107] It is also understood that, as the content of ZnO has a
value of below 10% by weight, a constant silver ion elution amount
can be stably maintained even when a deviation in the ZnO content
occurs during the process of producing an antimicrobial glass, for
example.
[0108] Furthermore, in FIG. 4, a characteristics curve in which the
ZnO content (% by weight) is plotted against the horizontal axis
when the total amount of the raw material of an antimicrobial glass
is 100% by weight and the silver ion elution amount (mg/(g1 liter24
Hrs30.degree. C.)) on Day 7 after immersion in purified water is
plotted against the vertical axis is shown.
[0109] Herein, the silver elution amount on Day 7 after immersion
in purified water is measured as described below.
[0110] Namely, after measuring the aforementioned reference silver
ion elution amount, 1 liter of the purified water containing eluted
silver ions is discarded, the antimicrobial glass remained after
dissolving is immersed in 1 liter of fresh purified water, and the
antimicrobial glass is immersed and kept for 5 days in purified
water at the same conditions as the conditions for measuring the
reference silver ion elution amount.
[0111] Subsequently, 1 liter of the purified water containing
eluted silver ions is discarded, the antimicrobial glass remained
after dissolving is immersed in 1 liter of fresh purified water and
kept for 24 hours at the same conditions as the conditions for
measuring the reference silver ion elution amount. After that, the
silver ion elution amount is measured and the result is used as a
silver ion elution amount on Day 7 after immersion in purified
water.
[0112] Furthermore, in FIG. 5, a characteristics curve in which the
ZnO content (% by weight) is plotted against the horizontal axis
when the total amount of the raw material of an antimicrobial glass
is 100% by weight and the silver ion elution amount (mg/(g1 liter24
Hrs30.degree. C.)) on Day 14 after immersion in purified water is
plotted against the vertical axis is shown.
[0113] Herein, the silver elution amount on Day 14 after immersion
in purified water is measured as described below.
[0114] Namely, after measuring the aforementioned silver ion
elution amount on Day 7 after immersion in purified water, 1 liter
of the purified water containing eluted silver ions is discarded,
the antimicrobial glass remained after dissolving is immersed in 1
liter of fresh purified water and kept for 6 days at the same
conditions as the conditions for measuring the reference silver ion
elution amount.
[0115] Subsequently, 1 liter of the purified water containing
eluted silver ions is discarded, the antimicrobial glass remained
after dissolving is immersed in 1 liter of fresh purified water and
kept for 24 hours at the same conditions as the conditions for
measuring the reference silver ion elution amount. After that, the
silver ion elution amount is measured and the result is used as a
silver ion elution amount on Day 14 after immersion in purified
water.
[0116] As it is understood from those characteristics curves, it is
found that, when the ZnO content has a value of 10% by weight or
more, the silver ion elution amount increases rapidly even on Day 7
or Day 14 after immersion in purified water, similar to Day 1 after
immersion in purified water (reference silver ion elution
amount).
[0117] As such, based on the characteristics curves shown in FIGS.
4 and 5, it is understood that, from the viewpoint of suppressing
coloration of a subject for washing not only at an early stage but
also over a long period of time, the content of ZnO as a raw
material is required to have a value of below 10% by weight.
[0118] Next, by using FIG. 6, the relationship between the ZnO
content and the dissolution speed of an antimicrobial glass over a
long period of time is described.
[0119] Specifically, in FIG. 6, a characteristics curve in which
the number of days (day) for immersing the antimicrobial glass in
purified water is plotted against the horizontal axis and the
weight (g) of the antimicrobial glass remained after dissolving is
plotted against the vertical axis is shown.
[0120] In addition, the characteristics curve A is a
characteristics curve having, as a subject for measurement, the
antimicrobial glass which has been produced in Example 1 described
below (ZnO content: 9.05% by weight, Ag.sub.2O content: 6% by
weight), the characteristics curve B is a characteristics curve
having, as a subject for measurement, the antimicrobial glass which
has been produced in Comparative Example 3 described below (ZnO
content: 13.8% by weight, Ag.sub.2O content: 6% by weight), and the
characteristics curve C is a characteristics curve having, as a
subject for measurement, the antimicrobial glass which has been
produced in Comparative Example 4 described below (ZnO content: 0%
by weight, Ag.sub.2O content: 3.04% by weight).
[0121] Meanwhile, the weight of the antimicrobial glass remained
after dissolving is measured according to the basically the same
method as the aforementioned method for measuring the reference
silver ion elution amount, the silver ion elution amount on Day 7
after immersion in purified water, and the silver ion elution
amount on Day 14 after immersion in purified water except that the
use amount of an antimicrobial glass was 20 g instead of 30 g.
[0122] Namely, for a case in which the weight of an antimicrobial
glass on Day 7 after immersion in purified water is measured after
measuring the weight of an antimicrobial glass on Day 1 after
immersion in purified water, the weight of an antimicrobial glass
on Day 1 after immersion in purified water is measured first, 1
liter of the purified water containing eluted silver ions is
discarded, the antimicrobial glass remained after dissolving is
immersed in 1 liter of fresh purified water, and kept for 6 days at
the same conditions as the conditions for measuring the reference
silver ion elution amount.
[0123] Subsequently, the weight of the antimicrobial glass remained
after dissolving is measured and the result is used as the weight
(g) of an antimicrobial glass on Day 7 after immersion in purified
water.
[0124] In addition, the process including discarding 1 liter of the
purified water containing eluted silver ions, immersing the
antimicrobial glass remained after dissolving in 1 liter of fresh
purified water, and keeping it until the next measurement day is
repeated.
[0125] Meanwhile, the weight of the antimicrobial glass remained
after dissolving is measured on Day 1, Day 7, Day 14, Day 30, . . .
, and Day 2555, and the measurement is terminated when the
antimicrobial glass is completely dissolved.
[0126] First, as it is understood from those characteristics curves
A and C, it is found that, for an antimicrobial glass with the ZnO
content of below 10% by weight, it takes 2000 days or so for 20 g
of the antimicrobial glass to dissolve completely, and thus it can
elute silver ions very stably over a long period of time.
[0127] Meanwhile, as it is understood from the characteristics
curve B, it is found that, when the ZnO content is a value of 10%
by weight or more, the time to have complete dissolution of 20 g of
the antimicrobial glass is significantly shortened, that is, 250
days or so, and thus it is difficult to have stable elution of
silver ions over a long period of time.
[0128] As such, from the viewpoint of maintaining stably a
predetermined silver ion elution amount over a long period of time,
it is understood that the content of ZnO as a raw material needs to
have a value of below 10% by weight.
[0129] Furthermore, by using FIG. 7, the relationship between the
ZnO and Ag.sub.2O content and silver ion concentration is
described.
[0130] Specifically, in FIG. 7, a characteristics curve in which
number of days (day) for immersing the antimicrobial glass in
purified water is plotted against the horizontal axis and the
silver ion concentration (mg/liter) in purified water in which the
antimicrobial glass is immersed is plotted against the vertical
axis is shown.
[0131] In addition, the characteristics curve A is a
characteristics curve having, as a subject for measurement, the
antimicrobial glass which has been produced in Example 1 described
below (ZnO content: 9.05% by weight, Ag.sub.2O content: 6% by
weight), the characteristics curve B is a characteristics curve
having, as a subject for measurement, the antimicrobial glass which
has been produced in Comparative Example 3 (ZnO content: 13.8% by
weight, Ag.sub.2O content: 6% by weight), and the characteristics
curve C is a characteristics curve having, as a subject for
measurement, the antimicrobial glass which has been produced in
Comparative Example 4 (ZnO content: 0% by weight, Ag.sub.2O
content: 3.04% by weight).
[0132] Meanwhile, the silver ion concentration in purified water is
measured according to the basically the same method as the
aforementioned method for measuring the reference silver ion
elution amount, the silver ion elution amount on Day 7 after
immersion in purified water, and the silver ion elution amount on
Day 14 after immersion in purified water except that the use amount
of an antimicrobial glass was 20 g instead of 30 g.
[0133] Namely, for a case in which the silver ion concentration on
Day 7 after immersion in purified water is measured after measuring
the silver ion concentration on Day 1 after immersion in purified
water, the silver ion concentration on Day 1 after immersion in
purified water is measured first, 1 liter of the purified water
containing eluted silver ions is discarded, the antimicrobial glass
remained after dissolving is immersed in 1 liter of fresh purified
water, and kept for 5 days in purified water at the same conditions
as the conditions for measuring the reference silver ion elution
amount.
[0134] Subsequently, 1 liter of the purified water containing
eluted silver ions is discarded, the antimicrobial glass remained
after dissolving is immersed in 1 liter of fresh purified water,
and after allowing it to stand for 24 hours at the same conditions
as the conditions for measuring the reference silver ion elution
amount, the silver ion concentration is measured and the result is
used as the silver ion concentration (mg/liter) on Day 7 after
immersion in purified water.
[0135] In addition, the process of keeping it until the next
measurement day is repeated.
[0136] Meanwhile, the silver ion concentration is measured on Day
1, Day 7, Day 14, Day 30, . . . , and Day 2555.
[0137] First, as it is understood from the characteristics curve A,
it is found that, for an antimicrobial glass with the ZnO content
of below 10% by weight and the Ag.sub.2O content of above 5% by
weight, the silver ion concentration of 1 to 2 mg/liter or so can
be stably maintained for at least 30 days even when the purified
water is exchanged during the process.
[0138] Accordingly, the subject for washing can be effectively
protected against microbes and an occurrence of black coloration of
the subject for washing can be effectively suppressed while an
occurrence of black mold or the like in a washing tub is
effectively suppressed.
[0139] Meanwhile, as it is understood from the characteristics
curve B, it is found that, for an antimicrobial glass with the ZnO
content of 10% by weight or more and the Ag.sub.2O content of above
5% by weight, the silver ion concentration can be maintained at
constant level, but as the silver ion concentration is very high
like 5 mg/liter or so, black coloration of the subject for washing
may easily occur when it is applied to an antimicrobial water unit
of a commercially available washing machine.
[0140] Furthermore, as it is understood from the characteristics
curve C, it is found that, for an antimicrobial glass with the ZnO
content of below 10% by weight and the Ag.sub.2O content of 5% by
weight or less, the silver ion concentration can be maintained at
constant level, but as the silver ion concentration is very low
like 0.5 mg/liter or so, it is difficult to have effective
protection of a subject for washing against microbes and effective
suppression of an occurrence of black mold or the like in a washing
tub when applied to an antimicrobial water unit of a commercially
available washing machine.
[0141] Accordingly, from the viewpoint of having effective
suppression of an occurrence of black mold or the like in a washing
tub and effective protection of a subject for washing against
microbes while suppressing coloration of a subject for washing, it
is understood that the content of ZnO as a raw material needs to
have a value of below 10% by weight and also the content of
Ag.sub.2O needs to have a value of above 5% by weight.
[0142] (5) K.sub.2O
[0143] K.sub.2O as a raw material basically functions as an oxide
for modifying a network, and it also relates to improvement of
transparency or control of melting temperature.
[0144] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of K.sub.2O as a raw
material has a value within the range of 5 to 20% by weight.
[0145] This is because, when the content of K.sub.2O has a value of
below 5% by weight, the solubility of the antimicrobial glass is
excessively lowered so that the silver ion elution amount becomes
insufficient to yield insufficient protection of a subject for
washing against microbes or the occurrence of black mold or the
like in a washing tub is not sufficiently suppressed. On the other
hand, when the content of K.sub.2O is a value of above 20% by
weight, the solubility of the antimicrobial glass is excessively
increased, and thus it becomes difficult to maintain a
predetermined silver ion elution amount over a long period of time
and black coloration of a subject for washing may easily occur due
to excessive silver ions.
[0146] As such, it is more preferable that the content of K.sub.2O
has a value within the range of 6 to 15% by weight. It is even more
preferably a value within the range of 7 to 9% by weight.
[0147] (6) Al.sub.2O.sub.3
[0148] Al.sub.2O.sub.3 as a raw material basically functions to
enhance the chemical durability of an antimicrobial glass, and it
is a substance also related to suppressing devitrification.
[0149] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of Al.sub.2O.sub.3
as a raw material has a value within the range of 1 to 10% by
weight.
[0150] This is because, when the content of Al.sub.2O.sub.3 has a
value of below 1% by weight, the solubility of the antimicrobial
glass is excessively increased so that it becomes difficult to
maintain a predetermined silver ion elution amount over a long
period of time and black coloration of a subject for washing may
easily occur due to excessive silver ions. On the other hand, when
the content of Al.sub.2O.sub.3 has a value of above 10% by weight,
the solubility of an antimicrobial glass is excessively lowered,
and thus the silver ion elution amount becomes insufficient to
yield insufficient protection of a subject for washing against
microbes or the occurrence of black mold or the like in a washing
tub is not sufficiently suppressed.
[0151] As such, it is more preferable that the content of
Al.sub.2O.sub.3 has a value within the range of 2 to 8% by weight.
It is even more preferably a value within the range of 3 to 5% by
weight.
[0152] Furthermore, it is preferable that, when the content of ZnO
is C1 (% by weight) and the content of Al.sub.2O.sub.3 is C2 (% by
weight), C2/C1 preferably has a value of 0.4 or more.
[0153] This is because, when the ratio between the content of ZnO
and the content of Al.sub.2O.sub.3 has such value, a predetermined
silver ion elution amount can be more stably maintained.
[0154] Namely, because ZnO as a raw material of the antimicrobial
glass of the present invention is a substance having an influence
of greatly increasing the solubility of the antimicrobial glass
while Al.sub.2O.sub.3 is a substance having an influence of greatly
decreasing the solubility of the antimicrobial glass, the ratio
between these raw materials has a strong relationship with the
solubility of an antimicrobial glass to be obtained.
[0155] More specifically, when C2/C1 has a value of below 0.4, the
solubility of an antimicrobial glass increases excessively so that
it becomes difficult to maintain stably a predetermined silver ion
elution amount over a long period of time and black coloration of a
subject for washing may easily occur due to excessive silver ions.
On the other hand, when C2/C1 has an excessively high value, the
solubility of an antimicrobial glass can be easily decreased to a
slightly lower value, and thus the antimicrobial property may be
impaired.
[0156] As such, it is preferable that, when the content of ZnO is
C1 (% by weight) and the content of Al.sub.2O.sub.3 is C2 (% by
weight), C2/C1 more preferably has a value within the range of 0.42
to 1.5. It even more preferably has a value within the range of
0.43 to 1.
[0157] Herein, by using FIGS. 8 to 10, the relationship between the
value of C2/C1 and a reference silver ion elution amount is
described.
[0158] First, in FIG. 8, a characteristics curve in which the C2/C1
(-) is plotted against the horizontal axis and the reference silver
ion elution amount (mg/(g1 liter24 Hrs30.degree. C.)) is plotted
against the vertical axis is shown.
[0159] Furthermore, as for the antimicrobial glass as a subject for
measurement, those produced in the Examples 1 to 3 and Comparative
Examples 1 and 2 described below were used.
[0160] Namely, the antimicrobial glass in which the contents of
Ag.sub.2O and CoO are not modified while the content of ZnO is
modified with modification of other components at the same ratio as
the change in ZnO content is used.
[0161] As it is understood from the characteristics curve, it is
found that the silver ion elution amount mg/(g1 liter24
Hrs30.degree. C.) decreases in accordance with an increase in C2/C1
(-).
[0162] More specifically, within the range in which C2/C1 is below
0.4, the silver ion elution amount rapidly decreases in accordance
with an increase in C2/C1, that is, it is 0.255 mg/(g1 liter24
Hrs30.degree. C.) when C2/C1 is 0.101 but it is decreased to 0.1245
mg/(g1 liter24 Hrs30.degree. C.) when C2/C1 is 0.208. When C2/C1 is
0.433, it is further decreased to 0.063 mg/(g1 liter24
Hrs30.degree. C.).
[0163] Meanwhile, within the range in which C2/C1 is 0.4 or more,
the value of 0.05 mg/(g1 liter24 Hrs30.degree. C.) or so is stably
maintained regardless of the C2/C1 value.
[0164] Furthermore, when the reference silver ion elution amount of
an antimicrobial glass has a value of 0.1 mg/(g1 liter24
Hrs30.degree. C.) or more, it was confirmed that the black
coloration of a subject for washing easily occurs when it is
applied to an antimicrobial water unit of a commercially available
washing machine.
[0165] As such, from the characteristics curve shown in FIG. 8, it
is understood that the C2/C1 is preferably adjusted to have a value
of 0.4 or less from the viewpoint of suppressing coloration of a
subject for washing.
[0166] Furthermore, in FIG. 9, a characteristics curve in which the
C2/C1 (-) is plotted against the horizontal axis and the silver ion
elution amount (mg/(g1 liter24 Hrs30.degree. C.)) based on 7 Days'
immersion in purified water is plotted against the vertical axis is
shown.
[0167] Furthermore, in FIG. 10, a characteristics curve in which
the C2/C1 (-) is plotted against the horizontal axis and the silver
ion elution amount (mg/(g1 liter24 Hrs30.degree. C.)) based on 14
Days' immersion in purified water is plotted against the vertical
axis is shown.
[0168] As it is understood from those characteristics curves, it is
found that, even on Day 7 and Day 14 after immersion in purified
water, the silver ion elution amount rapidly decreases within the
range in which C2/C1 is less than 0.4, similar to the Day 1 after
immersion in purified water (reference silver ion elution
amount).
[0169] As such, based on the characteristics curves shown in FIGS.
9 and 10, it is understood that, from the viewpoint of suppressing
coloration of a subject for washing not only at an early stage but
also over a long period of time, the C2/C1 is preferably adjusted
to a value of 0.4 or more.
[0170] (7) MgO
[0171] MgO as a raw material basically functions as an oxide for
forming a network, and it also relates to improvement of
transparency or control of melting temperature.
[0172] Furthermore, the antimicrobial glass of the present
invention is characterized in that the content of MgO as a raw
material has a value within the range of 5 to 20% by weight.
[0173] This is because, when the content of MgO has a value of
below 5% by weight, the solubility of the antimicrobial glass is
excessively increased, and thus it becomes difficult to maintain
stably a predetermined silver ion elution amount over a long period
of time and black coloration of a subject for washing may easily
occur due to excessive silver ions. On the other hand, when the
content of MgO has a value of above 20% by weight, the solubility
of an antimicrobial glass is excessively decreased so that the
silver ion elution amount becomes insufficient to yield
insufficient protection of a subject for washing against microbes
or the occurrence of black mold or the like in a washing tub is not
sufficiently suppressed.
[0174] As such, it is more preferable that the content of MgO has a
value within the range of 6 to 15% by weight. It is even more
preferably a value within the range of 7 to 9% by weight.
[0175] (8) Other Components
[0176] Furthermore, when the total amount of the raw materials is
less than 100% by weight, it is preferable to contain, as a
residual component, other glass components (alkali metal oxide,
alkali earth metal oxide, CeO.sub.2, CoO, or the like) within the
range of 0.05 to 50% by weight.
3. Shape
[0177] The antimicrobial glass is also characterized in that it has
a tablet shape with a maximum diameter value within the range of 5
to 20 mm.
[0178] This is because, as the antimicrobial glass has a shape with
a maximum diameter as described above, a predetermined elution
amount of silver ions can be stably maintained, together with the
aforementioned composition of an antimicrobial glass, over a long
period of time even if it is a compact amount.
[0179] Specifically, as the antimicrobial glass has a tablet shape,
the surface area of an antimicrobial glass can be easily
controlled, and also the silver ion elution amount can be more
easily controlled.
[0180] Furthermore, with a tablet shape, binding between
antimicrobial glasses can be also effectively prevented.
[0181] More specific examples include an antimicrobial glass having
a trapezoidal crossed hexahedral shape as shown in FIG. 11, but it
can be also a so-called tablet shape like rectangular or columnar
shape.
[0182] It is also preferable that chamfering is performed along the
sides of an antimicrobial glass.
[0183] This is because, by having this shape, the molding property
or polishing property can be also improved.
[0184] Furthermore, an antimicrobial glass with such shape can be
easily handled or replaced and also loss or breaking caused by
water flow can be effectively prevented even when a relatively
strong water flow is used.
[0185] Furthermore, if the maximum diameter of an antimicrobial
glass has a value of below 5 mm, when it is accommodated in an
antimicrobial water unit and brought into direct contact with
water, it can flow by water pressure so that it can be easily lost
together with water flow, or there can be a case in which the
specific surface area becomes excessively large so that a
predetermined silver ion elution amount may not be stably
maintained over a long period of time. Further, it can be easily
aggregated during storage. On the other hand, when the maximum
diameter of an antimicrobial glass has a value of above 20 mm, it
may be difficult to accommodate it in an antimicrobial water unit
or to have stable production due to easy occurrence of cracks, and
there can be a case in which the specific surface area becomes
excessively small so that it becomes difficult to obtain a
sufficient silver ion elution amount.
[0186] As such, it is more preferable that the maximum diameter of
an antimicrobial glass has a value within the range of 7 to 15 mm,
and even more preferably a value within the range of 9 to 12
mm.
[0187] Meanwhile, the maximum diameter of an antimicrobial glass
means a diameter of a sphere circumscribing the antimicrobial
glass.
[0188] Furthermore, the maximum diameter of an antimicrobial glass
can be easily measured by using an optical microscopic image or a
nonius.
4. Specific Surface Area
[0189] The antimicrobial glass preferably has a specific surface
area value within the range of 0.1 to 5 cm.sup.2/g.
[0190] This is because, by having the specific surface area of an
antimicrobial glass in the aforementioned range, a predetermined
silver ion elution amount can be more stably maintained over a long
period of time.
[0191] Namely, when the antimicrobial glass preferably has a
specific surface area value of below 0.1 cm.sup.2/g, the
dissolution speed of an antimicrobial glass is lowered to yield an
insufficient silver ion elution amount, and thus protection of a
subject for washing against microbes becomes insufficient or an
occurrence of black mold or the like in a washing tub may not be
sufficiently suppressed. On the other hand, when the antimicrobial
glass preferably has a specific surface area value of above 5
cm.sup.2/g, the solubility of an antimicrobial glass is increased
to yield an excessive silver ion elution amount, and thus it
becomes difficult to maintain stably a predetermined silver ion
elution amount over a long period of time. Further, the black
coloration of a subject for washing caused by excessive silver ions
may easily occur.
[0192] As such, it is more preferable that the specific surface
area of an antimicrobial glass is a value within the range of 1.5
to 8 cm.sup.2/g, and even more preferably a value within the range
of 2 to 5 cm.sup.2/g.
5. Reference Silver Ion Elution Amount
[0193] The antimicrobial glass of the present invention preferably
has a silver ion elution amount value, that is, reference silver
ion elution amount, within the range of 0.025 to 0.1 mg/(g1 liter24
Hrs30.degree. C.), which is measured by, after immersing 30 g of
the antimicrobial glass as a subject for measurement in 1 liter of
purified water (30.degree. C., pH 6.5), performing the measurement
after keeping it in a closed system for 24 hours with the
temperature maintained.
[0194] This is because, by having the reference silver ion elution
amount of an antimicrobial glass in the aforementioned range, a
predetermined silver ion elution amount can be more stably
maintained over a long period of time.
[0195] Namely, when the reference silver ion elution amount has a
value of below 0.025 mg/(g1 liter24 Hrs30.degree. C.), protection
of a subject for washing against microbes becomes insufficient or
an occurrence of black mold or the like in a washing tub may not be
sufficiently suppressed. On the other hand, when the reference
silver ion elution amount has a value of above 0.1 mg/(g1 liter24
Hrs30.degree. C.), it becomes difficult to maintain stably a
predetermined silver ion elution amount over a long period of time
and also black coloration of a subject for washing caused by
excessive silver ions may easily occur.
[0196] As such, it is more preferable that the reference silver ion
elution amount of an antimicrobial glass is a value within the
range of 0.04 to 0.08 mg/(g1 liter24 Hrs30.degree. C.), and even
more preferably a value within the range of 0.06 to 0.07 mg/(g1
liter24 Hrs30.degree. C.)
6. Coated Member
[0197] The antimicrobial glass of the present invention is
preferably accommodated inside a coated member which is provided
with an opening for passing water therethrough, that is, prepared
as a cartridge.
[0198] This is because, when accommodated in such a coated member,
not only the handling becomes easier but alto the loss caused by
flow water can be prevented even when the antimicrobial glass is
reduced to a small size according to use for a long period of
time.
[0199] Further, with an antimicrobial glass as accommodated in
advance in a coated member, a constant amount of an antimicrobial
glass can be easily accommodated in the antimicrobial water unit 10
that is shown in FIGS. 2(a) and 2(b).
[0200] Meanwhile, the antimicrobial water unit 10 that is shown in
FIGS. 2(a) and 2(b) is also a kind of a coated member.
[0201] Furthermore, the coated member can be prepared as a
mesh-like envelope product 20 as shown in FIGS. 12(a) and 12(b),
for example.
[0202] More specifically, it preferably consists of a mesh having a
hole size of 50 to 500 .mu.m or so, which is composed of
polypropylene or the like, and is prepared as an envelope product
with a size of 105.times.45.times.17 mm or so.
[0203] Furthermore, the envelope product preferably has a mode in
which the antimicrobial glass is accommodated while the seal part
28b and 28c are installed in advance and the seal part 28a is
installed as a final step.
[0204] Meanwhile, the accommodation amount of the antimicrobial
glass preferably has a value within the range of 10 to 30 g, and
more preferably has a value within the range of 15 to 25 g.
[0205] Furthermore, as shown in FIG. 12(b), it is preferable that
the antimicrobial glass 22 of the present invention is accommodated
inside the coated member 20, together with the non-antimicrobial
glass 26.
[0206] This is because, as it is accommodated together with a
non-antimicrobial glass, binding between antimicrobial glasses is
prevented so that a predetermined silver ion elution amount can be
more stably maintained over a long period of time.
[0207] Meanwhile, the type of a non-antimicrobial glass is not
particularly limited if it is a glass not allowing elution of
silver ions upon dissolution in water. Preferred examples include,
however, soda glass, borosilicate glass, lead glass (crystal
glass), quartz glass, aluminum silicate glass, and phosphate
glass.
[0208] More specifically, it is preferably a non-antimicrobial
glass having, as a main component, soda glass obtained by adding
SiO.sub.2 or the like as a glass network component, within the
range of 35 to 65% by weight and also, as a glass network-modifying
component, at least one of Na.sub.2O, K.sub.2O, Li.sub.2O, CaO,
MgO, BaO, B.sub.2O.sub.3, and Al.sub.2O.sub.3 within the range of
15 to 45% by weight relative to the total amount.
[0209] Furthermore, the shape of a non-antimicrobial glass is not
particularly limited. However, it is preferably a non-antimicrobial
glass with different shape as shown in FIG. 13, for example.
[0210] This is because, with such shape, not only easy molding can
be achieved but also the balance weight effect for water flow can
be effectively exhibited.
[0211] Furthermore, regarding the size of a non-antimicrobial
glass, the maximum diameter preferably has a value within the range
of 3 to 30 mm.
[0212] This is because such non-antimicrobial glass can have
substantially the same maximum diameter as that of an antimicrobial
glass so that it can be easily and homogeneously mixed with an
antimicrobial glass while it is hardly get localized.
[0213] Furthermore, the blending amount of a non-antimicrobial
glass preferably has a value within the range of 5 to 15% by weight
relative to 100 parts by weight of an antimicrobial glass.
[0214] This is because, with such blending amount of a
non-antimicrobial glass, not only a predetermined antimicrobial
property of an antimicrobial glass can be exhibited but also the
overall weight of a cartridge can be easily controlled.
[0215] Thus, from this point of view, the blending amount of a
non-antimicrobial glass more preferably has a value within the
range of 7 to 12 parts by weight, and even more preferably has a
value within the range of 8 to 11 parts by weight relative to 100
parts by weight of an antimicrobial glass
EXAMPLES
[0216] Hereinbelow, the antimicrobial glass of the present
invention is described in more detail by way of examples. However,
the following examples are only to illustrate the present
invention, and the present invention is not limited to those
descriptions.
Example 1
1. Production of Antimicrobial Glass
[0217] (1) Melting Process
[0218] As an antimicrobial glass composition, a glass feedstock
having the composition shown in Table 1 was stirred until uniformly
mixed by using a universal mixer at a rotational speed of 250 rpm
for 30 minutes.
[0219] Subsequently, using a glass melting furnace, the glass
feedstock was heated at 1280.degree. C. for 3.5 hours to produce
molten glass.
[0220] (2) Molding Process
[0221] As shown in FIGS. 14(a) and 14(b), the molten glass 42 taken
out from the glass melting furnace was introduced to the molding
device 40, and thus the antimicrobial glass 22 in the form of
tablet shape as shown in FIG. 11 (maximum diameter: 10 mm, surface
area of one piece: 2.5 cm.sup.2) was molded.
[0222] (3) Surface Grinding Process
[0223] 500 g of the obtained antimicrobial glass in the form of
tablet were charged into a vibration ball mill using no medium.
Subsequently, 500 g of isopropyl alcohol was added, and the
vibration ball mill was operated at room temperature for 30 minutes
in that state, thereby carrying out the surface grinding process
including deburring step.
[0224] As a result, although minute irregularities were found
before the surface grinding process, the surface was smooth and
glossy after the surface grinding process. The resulting glass was
used as the final antimicrobial glass.
[0225] The specific surface area of the obtained antimicrobial
glass was 3.75 cm.sup.2/g.
2. Evaluation of Antimicrobial Glass
[0226] (1) Measurement of Reference Silver Ion Elution Amount
[0227] The reference silver ion elution amount of the obtained
antimicrobial glass was measured.
[0228] More specifically, 30 g of the obtained antimicrobial glass
was immersed in 1 liter of purified water (30.degree. C., pH 6.5),
and allowed to stand in a closed system for 24 hours with the
temperature maintained.
[0229] Subsequently, the silver ion elute was filtered through a
filter paper (5C) to have a measurement sample, and then the silver
ion concentration in the measurement sample was measured using a
silver ion meter (manufactured by Toko Chemical Laboratories Co.,
Ltd., silver ion meter TiN-5104), and the reference silver ion
elution amount in the antimicrobial glass (mg/(g1 liter24
Hrs30.degree. C.)) was calculated. The obtained results are listed
in Table 2.
[0230] (2) Evaluation of Silver Ion Elution Amount after 7 Days
[0231] The silver ion elution amount in the obtained antimicrobial
glass after 7 days was measured.
[0232] Namely, after measuring the reference silver ion elution
amount described above, 1 liter of purified water containing eluted
silver ions was discarded, the antimicrobial glass remained after
dissolving was immersed in 1 liter of fresh purified water, and the
antimicrobial glass was immersed in purified water at the same
conditions as the conditions for measurement of the reference
silver ion solution amount and allowed to stand for 5 days.
[0233] Subsequently, 1 liter of the purified water containing
eluted silver ions was discarded, the antimicrobial glass remained
after dissolving was immersed in 1 liter of fresh purified water,
and after allowing it to stand for 24 hours at the same conditions
as the conditions for measuring the reference silver ion elution
amount, the result was used as the silver ion elution amount after
7 days (mg/(g1 liter24 Hrs30.degree. C.)). The obtained result is
shown in Table 2.
[0234] (3) Evaluation of Silver Ion Elution Amount after 14
Days
[0235] The silver ion elution amount in the obtained antimicrobial
glass after 14 days was measured.
[0236] Namely, after measuring the silver ion elution amount on Day
7 after immersion in purified water as described above, 1 liter of
purified water containing eluted silver ions was discarded, the
antimicrobial glass remained after dissolving was immersed in 1
liter of fresh purified water, and the antimicrobial glass was
allowed to stand for 6 days at the same conditions as the
conditions for measurement of the reference silver ion solution
amount.
[0237] Subsequently, 1 liter of the purified water containing
eluted silver ions was discarded, the antimicrobial glass remained
after dissolving was immersed in 1 liter of fresh purified water,
and after allowing it to stand for 24 hours at the same conditions
as the conditions for measuring the reference silver ion elution
amount, the silver ion elution amount was measured and the result
was used as the silver ion elution amount after 14 days (mg/(g1
liter24 Hrs30.degree. C.)). The obtained result is shown in Table
2.
[0238] (4) Evaluation of Antimicrobial Property
[0239] (4)-1 Bacteria Halo Test
[0240] By using the obtained antimicrobial glass, the bacteria halo
test (based on JIS L 1902) was performed.
[0241] Namely, on a pour plate medium with Staphylococcus aureus
(Staphylococcus aureus NBRC 12732), one of the obtained
antimicrobial glasses was tightly adhered followed by culture for
24 hours in an environment of 37.+-.2.degree. C. Thereafter, width
(mm) of a transparent zone of growth inhibition (halo) occurred
near the antimicrobial glass was measured. The obtained result is
shown in Table 1. Furthermore, the photographic image of the pour
plate medium obtained therefrom was shown in FIG. 15.
[0242] In addition, the halo test was also carried out by using
Escherichia coli (Escherichia coli NBRC 3301) instead of
Staphylococcus aureus. The obtained result is shown in Table 2.
Furthermore, the photographic image of the pour plate medium
obtained therefrom was shown in FIG. 16.
[0243] (4)-2 Mold Halo Test
[0244] By using the obtained antimicrobial glass, the mold halo
test (based on JIS L 1902) was performed.
[0245] Namely, on a plate medium which has been inoculated with
Aspergillus niger (Aspergillus niger NBRC 105649), one of the
obtained antimicrobial glasses was tightly adhered followed by
culture for 24 hours in an environment of 28.+-.2.degree. C.
Thereafter, width (mm) of a transparent zone of growth inhibition
(halo) occurred near the antimicrobial glass was measured. The
obtained result is shown in Table 2. Furthermore, the photographic
image of the plate medium obtained therefrom was shown in FIG.
17.
[0246] In addition, the halo test was also carried out by using
each of Penicillium (Penicillium citrinum NBRC 6352), black mold
(Cladosporium cladosporioides NBRC 6348) and Trichophyton
(Trichophyton mentagrophytes NBRC 32409) instead of Aspergillus
niger. The obtained result is shown in Table 2. Furthermore, the
photographic image of the plate medium obtained therefrom was shown
in each of FIGS. 18, 19 and 20.
[0247] Meanwhile, the aforementioned evaluation of antimicrobial
property was performed only in Example 1.
[0248] (5) Evaluation of Occurrence of Black Mold or the Like in
Washing Tub
[0249] The obtained antimicrobial glass was actually applied to a
washing machine, and an occurrence of black mold or the like in
washing tub was evaluated.
[0250] Namely, 20 g of the obtained antimicrobial glass was
accommodated in an antimicrobial water unit of a drum type washing
machine as shown in FIG. 1(a), and 5 kg of a subject for washing
(white underwear made of cotton) was washed once a day for 100 days
from June to September.
[0251] Subsequently, after washing for 100 days, an occurrence of
black mold or the like on a backside of the washing tub was
observed with a naked eye, and evaluated according to the following
criteria. The obtained result is shown in Table 2.
[0252] .circleincircle.: Black mold or the like is not observed at
all.
[0253] .largecircle.: Black mold or the like is hardly
observed.
[0254] .DELTA.: Black mold or the like is somewhat observed.
[0255] X: Black mold or the like is clearly observed.
[0256] (6) Evaluation of Antimicrobial Property and Coloration
Property of Subject for Washing
[0257] The obtained antimicrobial glass was actually applied to a
washing machine, and the antimicrobial property and coloration
property of a subject for washing were evaluated.
[0258] Namely, the white cotton underwear after washing for 100
days, which has been obtained after performing the evaluation of an
occurrence of black mold or the like in washing tub as described
above, was allowed to stand for 48 hours under exposure to sunlight
in an environment including temperature of 35.degree. C. and
humidity of 95% Rh. Then, it was subjected to an evaluation of
antimicrobial property and coloration property according to the
following criteria. The obtained result is shown in Table 2.
[0259] .circleincircle.: Malodor and darkish color are not observed
at all.
[0260] .largecircle.: Malodor or darkish color is hardly
observed.
[0261] .DELTA.: Malodor or darkish color is somewhat observed.
[0262] X: Malodor or darkish color is clearly observed.
Example 2
[0263] According to Example 2, an antimicrobial glass was produced
and evaluated in the same manner as Example 1 except that, with
regard to a composition of an antimicrobial glass, the contents of
Ag.sub.2O and CoO were maintained but the content of ZnO was
reduced to 4.05% by weight and ratio of other components was
increased as much as the reduced content of ZnO, as shown in Table
1. The obtained result is shown in Table 1.
Example 3
[0264] According to Example 3, an antimicrobial glass was produced
and evaluated in the same manner as Example 1 except that, with
regard to a composition of an antimicrobial glass, the contents of
Ag.sub.2O and CoO were maintained but the content of ZnO was
reduced to 0% by weight and ratio of other components was increased
as much as the reduced content of ZnO, as shown in Table 1. The
obtained result is shown in Table 1.
Comparative Example 1
[0265] According to Comparative Example 1, an antimicrobial glass
was produced and evaluated in the same manner as Example 1 except
that, with regard to a composition of an antimicrobial glass, the
contents of Ag.sub.2O and CoO were maintained but the content of
ZnO was increased to 14.05% by weight and ratio of other components
was decreased as much as the increased content of ZnO, as shown in
Table 1. The obtained result is shown in Table 1.
Comparative Example 2
[0266] According to Comparative Example 2, an antimicrobial glass
was produced and evaluated in the same manner as Example 1 except
that, with regard to a composition of an antimicrobial glass, the
contents of Ag.sub.2O and CoO were maintained but the content of
ZnO was increased to 19.05% by weight and ratio of other components
was decreased as much as the increased content of ZnO, as shown in
Table 1. The obtained result is shown in Table 1.
Comparative Example 3
[0267] According to Comparative Example 3, an antimicrobial glass
was produced and evaluated in the same manner as Example 1 except
that the composition of an antimicrobial glass was modified to have
the composition shown in Table 1. The obtained result is shown in
Table 1.
[0268] Meanwhile, the antimicrobial glass of Comparative Example 3
is a type of an antimicrobial glass with large silver ion elution
amount, which is used for a drain pan of an air conditioner.
Comparative Example 4
[0269] According to Comparative Example 4, an antimicrobial glass
was produced and evaluated in the same manner as Example 1 except
that the composition of an antimicrobial glass was modified to have
the composition shown in Table 1. The obtained result is shown in
Table 1.
[0270] Meanwhile, the antimicrobial glass of Comparative Example 4
is a type of an antimicrobial glass with small silver ion elution
amount, which has been conventionally used for an antimicrobial
water unit of a washing machine.
TABLE-US-00001 TABLE 1 Composition of antimicrobial glass Ag.sub.2O
P.sub.2O.sub.5 CaO ZnO K.sub.2O Al.sub.2O.sub.3 MgO Na.sub.2O
B.sub.2O.sub.3 CeO.sub.2 CoO (% by (% by (% by (% by (% by (% by (%
by (% by (% by (% by (% by C2/C1 weight) weight) weight) weight)
weight) weight) weight) weight) weight) weight) weight) (--)
Example 1 6.00 62.65 2.30 9.05 8.00 3.92 8.00 0.00 0.00 0.00 0.08
0.433 Example 2 6.00 63.65 3.30 4.05 9.00 4.92 9.00 0.00 0.00 0.00
0.08 1.215 Example 3 6.00 64.46 4.11 0.00 9.81 5.73 9.81 0.00 0.00
0.00 0.08 -- Comparative 6.00 61.65 1.30 14.05 7.00 2.92 7.00 0.00
0.00 0.00 0.08 0.208 Example 1 Comparative 6.00 60.65 0.30 19.05
6.00 1.92 6.00 0.00 0.00 0.00 0.08 0.101 Example 2 Comparative 6.00
57.80 0.00 13.80 14.00 0.00 6.70 1.70 0.00 0.00 0.03 0 Example 3
Comparative 3.04 66.80 21.99 0.00 0.00 2.00 0.00 0.60 5.00 0.52
0.05 -- Example 4
TABLE-US-00002 TABLE 2 Reference Silver ion Silver ion silver ion
elution elution elution amount after amount after amount 7 days 14
days (mg/(g 1 (mg/(g 1 (mg/(g 1 Antimicrobial property (halo width)
(mm) liter 24 Hrs liter 24 Hrs liter 24 Hrs Staphylococcus
Escherichia Aspergillus 30.degree. C.)) 30.degree. C.)) 30.degree.
C.)) aureus coli niger Example 1 0.063 0.039 0.030 3.3 3.0 2.0
Example 2 0.055 0.046 0.033 Example 3 0.048 0.036 0.029 Comparative
0.125 0.116 0.115 Example 1 Comparative 0.255 0.219 0.234 Example 2
Comparative 0.303 0.251 0.255 Example 3 Comparative 0.023 0.019
0.024 Example 4 Antimicrobial property and Antimicrobial property
Occurrence coloration (halo width) (mm) of black property of Black
mold in subject for Penicillium mold Trichophyton washing tub
washing Example 1 3.5 4.8 0.5 .largecircle. .largecircle. Example 2
.DELTA. .largecircle. Example 3 .DELTA. .largecircle. Comparative
.circle-w/dot. X Example 1 Comparative .circle-w/dot. X Example 2
Comparative .circle-w/dot. X Example 3 Comparative .largecircle.
.largecircle. Example 4
INDUSTRIAL APPLICABILITY
[0271] According to the antimicrobial glass of the present
invention, as the composition of an antimicrobial glass for
releasing silver ion when brought into direct contact with water is
set to a predetermined composition and the shape and maximum
diameter of the glass are adjusted to be in a predetermined range,
it is possible to stably maintain a predetermined elution amount of
silver ions over a long period of time, even if it is a compact
amount.
[0272] As a result, it can be stored in a narrow accommodation
space in an antimicrobial water unit for supplying antimicrobial
water to a washing tub of a washing machine, an occurrence of black
mold or the like in a washing tub can be effectively suppressed,
and a subject for washing can be effectively protected against
microbes while suppressing the coloration of the subject.
[0273] As such, the antimicrobial glass of the present invention is
expected to significantly contribute to achieving high quality of
an antimicrobial glass for a washing machine, in particular.
EXPLANATIONS OF LETTERS OR NUMERALS
[0274] 1a: Drum type washing machine [0275] 1b: Stand type washing
machine [0276] 2: Washing tub [0277] 3: Cover [0278] 4: Circulating
water path [0279] 6: Part of wall surface of washing tub [0280] 10:
Antimicrobial water unit [0281] 12: Opening [0282] 14: Fixing hole
[0283] 16: Hinge part [0284] 18: Lock part [0285] 20: Coated member
[0286] 22: Antimicrobial glass [0287] 26: Non-antimicrobial glass
[0288] 28: Seal part, [0289] 40: Molding device [0290] 42: Molten
glass
* * * * *