- 1 - 2l3~9
An Antibacterial Porous Inorqanic Capsule and
a Process for Producinq the Same
Background of the Invention
Technical Field of the Invention
The present invention relates to an antibacterial
porous inorganic capsule and a process for producing the
same. More specifically, the present invention relates to
an antibacterial porous inorganic capsule utilizing one or
more than one antibacterial agents selected from the group
consisting of antibacterial zeolite, antibacterial
zirconium, antibacterial apatite, silver oxide, zinc oxide,
zinc sulfide and copper sulfide, and a process for producing
the same.
Prior Art
It is known that a silver ion, a zinc ion, a copper ion
and the like have an antibacterial property. However, a
practically usable antibacterial property cannot be expected
by metal of silver since generation of metal ion thereby is
scarce. An aqueous solution of silver nitrate has some
antibacterial property because of generation of a silver
ion, however, such silver nitrate is difficult to actually
use because it is water-soluble. When silver nitrate is
admixed with coating compounds or plastics, the quantity of
flown out silver exceeds the allowable llmit. 'rhe qualltity
of silver is restricted to be below 50 ppb in -the United
States of America and below 100 ppb in Germany.
Accordingly, in case of an antibacterial agent which uses
silver, the quantity of flown out ~ilver must be minimized
50 as to be within safety range. Since silver sulfate, zinc
sulfate, copper sulfate, copper nitrate, silver perchlorate,
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zinc perchlorate, copper perchlorate, silver acetate, copper
acetate, zinc acetate or the like considerably flows out
into water, there is a problem with respect to its safety,
and it has a defect that a lonq lasting antibacterial effect
cannot be obtained.
As a material which is water-insoluble and which is so
controlled that generation of metal ion is not excessive,
antibacterial zeolite, antibacterial zirconium or
antibacterial apatite, i.e., a part of or all of ions in
zeolite, zirconium or apatite are ion-exchanged with metal,
such as silver, zinc, copper or the like, having a
antibacterial property, has been developed.
Such agents as antibacterial zeolite have a good
antibacterial property against water-mold, high safety of
men and a long lasting antibacterial property, and they are
expected to be used in various technical fields, such as
water treatment. However, since such agents as
antibacterial zeolite are powder, the size of which is about
1 to 2 micron meter tin case of synthetic zeolite) or at
most about 300 micron meter (in case of natural zeolite),
they are very difficult as they are. In other words, they
have to be mixed with other materials or bonded to other
materials so that they can be easily dealt with upon use.
Thus, the powder antibacterial agents have been admixed with
synthetic resin such as polyester or polyamide so that they
are used in the form of fibers or molded article.
Problems to Be Solve by the Invention
However, the above-described conventional antibacterial
zeolite has a problem that it is discolored by metal ions.
When it is mixed with synthetic resin or applied to
synthetic resin using binder, there is a defect that it is
discolored into dark brown in the course of time, and this
tendency becomes more remarkable in presence of moisture,
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light and absorbed material. Especially, in case of
products which are given sanitary conditions by means of
antibacterial property, users tend to dislike contamination
thereof due to discoloration.
Further, presence of moisture is important for
antibacterial agents such as antibacterial zeolite to fully
achieve their antibacterial effects. If they are admixed
with synthetic resin or binder, there is a serious problem
of decrease of antibacterial effect since the synthetic
resin shields moisture. Thus, even when the above-described
antibacterial zeolite or the like is actually used,
antibacterial effects cannot be achieved compared with those
which were expected before its actual use.
Objects of the Invention
The present invention has been achieved taking into
consideration the above-described various problems.
It is an object of the present invention to provides
improved antibacterial powder which does not decrease its
antibacterial effects when it is mixed with synthetic resin
or binder and which is free from discoloration due to metal
ions.
Summary of the Invention
According to the present invention, the above-described
object is achieved by substantlally enclos.ing antibacterial
agent with water-insolubl0 porous inorganic compound, in
other words, encapsulating said antibacterial agent with
said water-insoluble porous inorganic compound.
Further, the present invention may use as the
antibacterial agent one or more than one among the
conventionally known antibacterial zeolite, antibacterial
zirconium, antibacterial apatite or the like. In addition,
4 2~ s ~
the present invention may use as the antibacterial agent
silver oxide, zinc oxide, zinc sulfide or copper sulfide
among silver compounds, zinc compounds and copper compounds
which have not been used as antibacterial agent.
Silver oxide, zinc oxide, zinc sulfide and copper
sulfide are slightly soluble in water, i.e., their
solubility in water is about 4x10-5 to 7x10-5 moles/liter.
More specifically, they are sightly dissolved in presence of
moisture and they generate metal ions, and thus achieve
antibacterial effects. Since silver oxide and copper
sulfide per se are originally colored in dark brown and
charcoal gray, if they are admixed with synthetic resin as
they are, the original colors appear in the obtained
products. Contrary to this, since silver oxide, zinc oxide,
zinc sulfide and copper sulfide are encapsulated according
to the present invention and converted into white powder,
they can be admixed with or used in synthetic resin,
synthetic fiber or coating compound without causing any
problem of color.
When either one of the following two processes for
producing an antibacterial porous inorganic capsule is
carried out, the above-described antibacterial agents are
surely encapsulated.
- ** First Process, i.e./ Interface Reaction Method:
This process comprises:
~ a first step for suspending at least one antibacterial
agent selected from the group consisting of antibacterial
zeolite, antibacterial zirconium, antibacterial apatite,
silver oxide, zinc oxide, zinc sulfide and coppe~ sulflde,
in an aqueous solution of hydroxide o~ alkaline metal to
form slurr~;
a second step for admixing said slurry obtained in said
first step with an aqueous solution of silicate of alkaline
metal;
a third step for making W/O emulsion by mixing
2Q~ sl l
dispersion obtained in said second step with an organic
solvent having a solubility in water of at most 7 ~; and
a fourth step for forming micro-porous particulate
matters by admixing and stirring said W/o emulsion obtained
in said third step with an aqueous solution of compound
which is capable of insolubilizing said alkaline metal
silicate.
** Second Process, i.e., Hydrolysis Method:
This process comprises:
a first step for dissolving alkoxide M(OR)n, wherein M
stands for metallic element, R stands for alkyl group and n
stands for atomic number of the metallic element, in a
solvent;
a second step for admixing at least one antibacterial
agent selected from the group consisting of antibacterial
zeolite, antibacterial zirconium, antibacterial apatite,
silver oxide, zinc oxide, zinc sulfide and copper sulfide,
in a solution obtained in said first step; and
a third step for adding a hydrolytic agent of said
alkoxide to dispersion obtained in said second step and
allowing them to react with each other.
The 'encapsulated" condition according to the present
invention means that the water-insoluble porous inorganic
compound is deposited around the antibacterial agent, i.e.,
one or more than one antibacterial agents selected from the
group consisting of antibacterial zeolite, antibacterial
zirconium, antibacterial apatite, silver oxide, zinc oxide,
zinc sulfide and copper sulfide, so that the antibacterial
agent is substantially enclosed by capsules made of porous
inorganic compound and hav.ing a plurality of micro pores.
The pore opening of the plurality of micro pores is
about several tens to several hundreds angstrom units and
depends on the kind and the concentration of the compound,
i.e., the silicate of the alkaline metal, which forms the
capsule as well as the kind and the concentration of the
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insolubilizing agents of the compound. For example, if the
concentration of both of them is high, capsules with large
diameter are separated out and accordingly, their pore
opening becomes large. The pore opening can be varied in
the above-described range.
Since micro-porous capsules are formed in accordance
with the interface reaction method or the hydrolysis method,
moisture is maintained within capsules even after the formed
capsules are powdered by filtering, washing and drying.
Moisture can freely pass through the membrane of the
capsules, and the capsules maintain moisture therein. Thus,
the enclosed antibacterial agent continues to generate a
small amount of metal ions under the influence of the
moisture. Accordingly, when the thus obtained antibacterial
agent is admixed with synthetic resin or binder, the
antibacterial effects are not decreased.
Silver oxide which is dark brown and copper sulfide
which is charcoal gray can be changed by means of
encapsulation into white micro-powder which can be admixed
with synthetic resin, synthetic fiber or coating compound.
In the meantime, since the antibacterial agents are
stored within the capsules, the color of the antibacterial
agents do not appear due to the shielding effects of the
capsule, and accordingly, the problem of discoloration
caused by antibacterial metal can be prevented from
occurring. More specifically, when the antibacterial porous
inorganic capsule of the present invention used with
synthetic resin or the like, the antibacterial effects
primarily caused by the antibacterial agents are not
deteriorated, and ionization is facilitated si.nce
appropriate amount of moisture is maintained in the capsules
as described above. Further, contamination due to
discoloration which may be caused by antibacterial agents
can be fully prevented from occurring.
In the interface reaction method, as a pretreatment of
20~95~
encapsulation, the antibacterial agents are added in an
aqueous solution of hydroxide of alkaline metal to form
slurry, and thus the dispersion properties of the
antibacterial agents in the aqueous solution of silicate of
alkaline metal are upgraded, and finally, the antibacterial
agents are encapsulated by porous inorganic compounds.
Further, by means of a simple method wherein hydrolysis
reaction of alkoxide is carried out while the antibacterial
agents exist together, the antibacterial agents can be
encapsulated, without loosing the primary antibacterial
property of the antibacterial agents, by porous inorganic
compound which are cre~ted during the hydrolysis reaction.
The first method, i.e., the interface reaction method,
is effective for obtaining porous capsules having large pore
openings in their porous material, and the second method,
i.e., the hydrolysis reaction method, is effective for
obtaining porous capsules having small thickness in membrane
of the encapsulating layer.
Detailed Description of the Invention
The present invention will now be explained
specifically in detail.
According to the first step of the first method, i.e.,
the interface reaction method, one or more than one
antibacterial agents, which are selected from the group
consisting of antibacterial zeolite, antibacterial
zirconium, antibacterial apatite, silver oxide, zinc oxide,
zinc sulfide and copper sulfide, are formed to slurry in an
aqueous solution of hydroxide oE alkaline metal. Examples
of suitable aqueous solution of hydroxide of alkaline metal
are an aqueous solution of caustic soda, caustic potash,
lithium hydroxide or the like. The concentration of the
hydroxide of alkaline metal in the aqueous solution may be
0.1 to 10 %, preferably about 0.2 to 3 %. The antibacterial
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agents and the aqueous solution of hydroxide of alkaline
metal are so prepared that the concentration of the
antibacterial agents in the obtained slurry is 20 to 60
wt.%, preferably 50 to 60 wt.%.
Some examples, which are commercially available, of the
antibacterial agents which may be used in the present
invention are as follows.
<Antibacterial Zeolite>
"ZEOMIC", the product by Shinanen Zeomic Corporation
"BACTEKILLER", the product by Xanebo, Ltd.
Antibacterial zeolite having a particle size of about 1
micron meter may be used, and preferably the particle size
is not more than 1 micron meter.
<Antibacterial Zirconium> (which is obtained by
absorbing silver to zirconium phosphate by means of ion
exchange.)
"NOVARON", the product by TOAGOSEI CHEMICAL INDUSTRY
Co. Ltd., powder having particle size of about 0.5 micron
meter
~ Antibacterial Apatite> (which is obtained by absorbing
silver to hydrated calcium phosphate by means of ion
exchange.)
"APACIDER-A", the product by Kabushiki Kaisha Sangi,
powder having a particle size of 1 to 2 micron meter
<Silver Oxide, Zinc Oxide, Zinc Sulfide, and Copper
Sulfide>
Those with particle size not more than 1 micron meter,
preferably not more than 0.5 micron meter are used.
Then, in the second step, the slurry is added with
stirring to an aqueous solution o~ silicate of alkaline
metal to form dispersion. In this instance, the
concentration of the antibacterial agents in the dispersion
is adjusted to be about 10 to 50 wt.%.
Silicate of Sodium, Lithium, Potassium may be used for
the silicate of alkaline metal. The appropriate quantity of
2 ~3 ~ r9 ~ ~ --
g
the added silicate is 2 to 6.5 moles/liter calculated as
sio2 .
In the third step, an organic solvent having a
solubility in water of at most 7 ~, is mixed to the
dispersion to make W/O emulsion. The organic solvents which
can be used for this step are exemplified as follows.
<Aliphatic Hydrocarbons>
n-Hexane, isohexane, n-heptane, isoheptane, n-octene,
iso-octene, gasoline, petroleum ether, kerosene, benzine,
mineral spirit and the like
<Alicyclic Hydrocarbons>
Cyclopentane, cyclohexane, cyclohexene, cyclononane and
the like
<Aromatic Hydrocarbons>
Benzene, toluene, xylene, ethylbenzene, propylbenzene,
cumene, mesitylene, tetralin, styrene and the like
<Ethers>
Propyl ether, isopropyl ether and the like
<Hydrocarbon Halides>
Methylene chloride, chloroform, ethylene chloride,
trichloroethane, trichloroethylene and the like
<Esters>
Ethyl acetate, n-propyl acetate, isopropyl acetate,
n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl
acetate, butyl lactate, methyl propionate, ethyl propionate,
methyl butyrate and the like
Organic solvent having a solubility in water being at
most 7 % may be used in this step for the organic solvent.
Should organic solvent having a solubiL:ity in water being
larger than 7 % be used in this step, even emulsion cannot
be obtained, and such an organic solvent is not preferred.
One or more than one organic solvents which have been
exemplified above are mixed to the dispersion obtained in
the second step to form emulsion. The organic solvents may
contain alcohols up to 10 wt.%. The quantity of the organic
2 0 ~
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solvent is not limited as long as the obtained emulsion is
of W/O type. The quantity of the organic solvent may be at
least 50 wt.% of the emulsion, preferably 70 to 80 wt.%.
The method for making emulsion may be conventionally
known one, such as stirring method, or shaking method.
Known emulsifying agent may be added upon emulsifying
operation. Nonionic surfactants preferably having HLs
(hydrophilic-lipophilic balance) of between 3.5 and 6.0 may
be used for the emulsifying agent. Examples of preferred
nonionic surfactants are as follows.
<Polyoxyethylene sorbitan fatty acid esters>
Polyoxyethylene sorbitan monolaurate, polyoxyethylene
sorbitan monopalmitate, polyoxyethylene sorbitan
monostearate, polyoxyethylene sorbitan tristearate,
polyoxyethylene sorbitan monooleate
<Polyoxyethylene higher alcohol ethers>
<Polyoxyethylene fatty acid esters>
<Glycerin fatty esters>
<Polyoxyethylene sorbitol fatty acid esters>
The quantity of the emulsifying agent may be at most 10
wt.%, preferably, between 0.01 and 3 wt.%, of the organic
solvent.
Thereafter, in the fourth step, the W/O emulsion
obtained in the third step is admixed with an aqueous
solution of compound which is capable of insolubilizing the
silicate of alkaline metal and is stirred for 20 to 30
minutes to react with each other. This reaction is to react
in the emulsion the aqueous solution containing the
antibacterial agent and the si.l:icate of alkaline~ metal with
the aqueous solution containing the compound which is
capable of insolubilizing the silicate of alkaline metal,
and this reaction is a kind of interface reaction. The
reaction takes place around the antibacterial agents, and
insolubilized inorganic compounds separate out around the
antibacterial agents, and porous inorganic capsules are
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formed.
The aqueous solution containing the compound which is
capable of insolubilizing the silicate of alkaline metal may
be sodium bicarbonate, potassium bicarbonate, ammonium
bicarbonate, calcium chloride, magnesium chloride, barium
chloride or the like.
Then, the materials wherein the inorganic compounds
separating out around the antibacterial agents are filtered,
washed and dried in accordance with the normal methods.
The particulars of the body of the capsule , i.e., the
receptacle portion of the porous inorganic capsule of the
present invention, obtained by means of the first method,
i.e., the interface reaction method, are as follows.
(a) Particle Size 0.05 to 300 micron meter
(b) Thickness of the Membrane of the Capsule
0.02 to 10 micron meter
(c) Degree of Porosity 0.1 to 5 cc/g
(d) Pore Opening in the Membrane of the Capsule
20 to 20000 angstrom unit
Some examples of the porous inorganic compounds which
are created in the above-described reaction and which form
the porous inorganic capsules of the present invention are
as follows.
Silicic acid, magnesium silicate, calcium silicate,
barium silicate.
~ The second process, i.e., the hydrolysis method will
now be explained. In the first and second steps, one or
more than one antibacterial agents, which are selected from
the group consisting of an~ibacterial zeolite, antibac~erial
zirconium, antibacterial apatite, silver oxide, zinc oxide,
zinc sulfide and copper sulfide, are dissolved in a so]ution
of alkoxide.
It is preferred to use alkoxide designated by M(OR)n,
wherein M stands for metallic element, R stands for alkyl
group and n stands for atomic number of the metallic
2 ~
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element, as the above-described alkoxide.
The metallic element M may be a hydroxide of metal
generated by hydrolysis or a metallic oxide obtained by
drying the hydroxide, and for example, metal coloring white
may be used. More specifically, Al (aluminum), Si
(Silicone), Ti (Titan), Zr (Zirconium) and so on are used.
The alkyl group designated by R has a carbon number of
between 1 and 20, preferably of between 1 and 5, and its
preferred examples are methyl, ethyl, propyl (including both
n- and iso-), butyl (including both n- and iso-) and so on.
A solvent which can dissolve the alkoxide is used, and
its examples are alcohols and aromatic hydrocarbons. More
specifically, ethanol, isopropyl alcohol and benzene are
exemplified. The concentration of the solvent of the
alkoxide is at most 90 %, preferably between about 10 and 30
%. One or more than one antibacterial agents, selected from
the group consisting of antibacterial zeolite, antibacterial
zirconium, antibacterial apatite, silver oxide, zinc oxide,
zinc sulfide and copper sulfide, are so dispersed in the
solution that the concentration of the antibacterial agents
become between 10 and 80 %. In this instance, a dispersant
may be used if necessary.
In the third step, a hydrolytic agent which can
hydrolyze the alkoxide is added to the dispersion thus
obtained in the second step, and the alkoxide is hydrolyzed.
The hydrolytic agent in this instance may be acid or alkali.
More specifically, ammonia, sodium hydroxide, hydrochloride
acid, acetate acid, sulfuric acid or the like may be used.
When acid is used for the hydrolytic agent, the
antibacterial agents may be dissolved. Therefore, use of
alkali for the hydrolytic agent is more preferred.
In this method, since hydrolysis reaction is used, it
is essential for the solution in which the antibacterial
agents are dispersed to contain water. The water may be
added together with the solvent in the preparing stage of
- 13 _ 2 ~
the solvent solution or may be added together with the
hydrolytic agent, for example, as ammonia wa-ter when ammonia
is used. The quantity of the water is satisfactory if
hydrolysis takes place and should be at least chemical
equivalent.
The added quantity of the hydrolytic agent is between
about 0.001 and 0.1 wt.% of the dispersion of the
antibacterial agents.
Due to this hydrolysis reaction, inorganic compounds
are formed around the antibacterial agents and encapsulate
the latter.
Some examples of the combinations of the alkoxide, its
solvent and hydrolytic agent are as follows.
When alkoxide is alkoxysilane, it is dissolved in
ethanol, i.e., the solvent (the first step), the
antibacterial agents are dispersed in this solution (the
second step), and ammonia water is added as the hydrolytic
agent (the third step). In this case, porous inorganic
capsules made of silicic acid are formed around the
antibacterial agents.
When alkoxide is tri-isopropyl oxide aluminum, it is
dissolved in isopropyl alcohol, i.e., the solvent (the first
step), the antibacterial agents are dispersed in this
solution (the second step), and hydrochloride acid of about
0.1 N is added as the hydrolytic agent (the third step).
Then, porous inorganic capsules wherein alumina encapsulates
around the antibacterial agents are obtained.
When alkoxide of Ti is used, capsules of titanium oxide
are formed, and alkoxide of Zr is used, capsules of
zirconium oxide are formed.
The particulars of the body of the capsule , i.e., the
receptacle portion of the porous inorganic capsule of the
present invention, obtained by means of the second method,
i.e., the hydrolysis reaction method, are as follows.
(a) Particle Size 0.05 to 300 micron meter
2~9~
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(b) Thickness of the Membrane of the Capsule
0.01 to l micron meter
(c) Degree of Porosity 0.05 to 1 cc/g
(d) Pore Opening in the Membrane of the Capsule
20 to 100 angstrom unit
Both of the above-described methods can produce the
antibacterial porous inorganic capsules of the present
invention wherein the inorganic compounds encapsulating
around the antibacterial agents. However depending on the
producing processes, i.e., the first process using the
interface reaction and the second process using the
hydrolysis reaction, the shell of the obtained capsules have
different properties. For example, they are different in
material, porosity, void content and thickness of membrane,
and the differences are caused by the differences in the raw
materials, the reaction processes, the concentrations of the
solutions and the conditions of the emulsion during the
capsulizing operation. Thus, the antibacterial properties
of the antibacterial porous inorganic capsules of the
present invention can be controlled by utilizing these
differences. Further, the particle size and the thickness
of the membrane of the capsule are also influenced upon by
the size of the antibacterial agents which are encapsulated
in the capsules.
Brief Description of the Drawings
Some examples of the antibacterial porous inorganic
capsules of the present invention are illllstrated in the
accompanying drawings, wherein:
Fig. 1 is a scanning electron photomicrograph
(magnification: x3000) of particles of antibacterial zeolite
which are before encapsulating process;
Fig. 2 is a scanning electron photomicrograph
(magnification: x3000) of antibacterial porous inorganic
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capsules of the present invention which are obtained by
encapsulating the antibacterial zeolite illustrated in Fig.
1 by means of the first process, i.e., interface reaction
method, of the present invention;
Fig. 3 is a scanning electron photomicrograph
(magnification: x3000) of particles of antibacterial zeolite
which are before encapsulating process; and
Fig. 4 is a scanning electron photomicrograph
(magnification: x3000) of antibacterial porous inorganic
capsules of the present invention which are obtained by
encapsulating the antibacterial zeolite illustrated in Fig.
3 by means of the second process, i.e., the hydrolysis
reaction method, of the present invention.
The antibacterial porous inorganic capsule of the
present invention can be widely used in various fields where
antibacterial properties are required, for example, in the
fields of fibers, papers, plastic products, sheets, vessels
and coating compounds.
Specific Examples
Some specific examples of the present invention will
now be described.
<Example 1>
-- 30 g of antibacterial zeolite was added to an aqueous
solution which obtained by dissolving 1 g of caustic soda in
50 g of water to form slurry. Then, the slurry was added
with stirring to 180 cc of an aqueolls solution Oe sodium
silicate (6.5 moles/liter) ~o Eorm di.spers.ion. 600 cc of
mixture was added to the dispersion. The mixture contained
normal-hexane and cyclo-hexane at khe mixing ratio of 1:1,
and also contained 15 g/liter of polyoxyethylene sorbitan
trioleate. Then, the mixture and the dispersion were
stirred for 1 minute at 6000 rpm to make ~/O emulsion. One
2 ~
- 16 -
liter of ammonium bicarbonate (1.5 moles/liter) was added to
the W/O emulsion. They were stirred for 30 minutes at room
temperature to react with each other. Then, they were
filtered to separate off cake. The case was washed with
water, cleaned with ethanol, and dried for 24 hours at 110
C. Thus, 100 g of antibacterial porous inorganic capsules
enclosing therewith the antibacterial zeolite and having a
mean particle size of 20 micron meter were obtained.
The obtained antibacterial porous inorganic capsules
were admixed with polyvinyl chloride, the quantity of the
capsule being 3 % of the polyvinyl chloride, and then, a
sheet having 3 mm thickness was manufactured by said
antibacterial polyvinyl chloride. A water storage tank was
constructed with the sheet.
The tank was used for storing industrial water, and no
contamination due to discoloration nor development of algae
or slime was observed after use for 6 months.
Further, when water, the general bacteria level of
which was 1.8 x 105 was poured in this storage tank, the
bacteria decreased to substantially zero after one day.
Thus, it was confirmed that the tank had antibacterial
effects.
<Example 2>
40 g of antibacterial zeolite was added to an aqueous
solution which obtained by dissolving l g of caustic soda in
50 g of water to form slurry. Then, the slurry was added
with stirring to 180 cc of an aqueous solution of sodium
silicate (6.5 moles/liter) to form dispersion. 600 cc of
cyclo-hexane solution containing 1 % of polyoxyethylene
sorbitan tristearate was added to the dispersion, and then,
they were stirred by means of a stirrer for 2 minutes at
7500 rpm to make W/O emulsion. One liter of magnesium
chloride (2 moles/liter) was added to the W/O emulsion.
They were stirred for 40 minutes at room temperature to
- 17 - 2~
react with each other. Then, they were filtered to separa-te
off cake, The cake was washed with water, cleaned, and
dried for 24 hours at 110 C. Thus, 157 g of antibacterial
porous inorganic capsules enclosing therewith the
antibacterial zeolite and having a mean particle size of 2
micron meter were obtained.
The antibacterial porous inorganic capsules were
admixed with polyethylene terephtalate, the quantity of the
capsule being 1 % of the polyethylene terephtalate, and
then, staple fibers of 3 denier were manufactured by the
mixture thus obtained. The obtained staple fibers were free
from discoloration by metallic ion. The thus obtained
polyester staple fibers were blended with cotton by 30 %,
and then, sheeting was woven from spun yarn of the blended
fibers.
When general bacteria, the level of which was 1.8 x
105, were inoculated on this sheeting, the level of the
bacteria decreased to less than 1 x 102 after one day.
Thus, it was confirmed that the sheeting had antibacterial
effects. The sheeting was used as a dishcloth, there
occurred no contamination due to discoloration by metallic
ion after use for 6 months.
<Example 3>
117 milliliter of ethanol was added and dissolved to
204 g of tetraethoxysilane, Si(OC2Hs)4, and 60 g of
antibacterial zeolite was added to the solution and
dispersed therein. Then, after adding 90 m:illiliter o~ 0.1
N ammonia water t the so]ut:ion, the solution was stirred for
10 minutes by means of an ultrasoni.c dispersion mixer, and
was heated at 60 C for 3 hours. Then, the solution was
filtered to separate off cake. The cake was dried at 110 C
for 24 hours, and thus 120 g of antibacterial porous
inorganic capsules having a mean particle size of 8 micron
meter were obtained.
- 18 -
The antibacterial porous inorganic capsules were
admixed with polyethylene, the quantity of the capsule being
6 ~ of the latter, and then, a sheet was made of the thus
obtained mixture. This sheet was free from contamination
due to discoloration.
When the sheet was used for wrapping meat,
proliferation of general bacteria did not occur after the
meat was left to stand at a room temperature for three days.
<Example 4>
204 g of tri-isopropyl oxide aluminum, Al(OC3H7)3 was
dissolved in 150 milliliter of isopropyl alcohol, and 50 g
of antibacterial zeolite was added to the solution and
dispersed therein by means of an ultrasonic dispersion
mixer. Then, after adding 60 milliliter of 0.1 N
hydrochloride acid to the solution, the solution was heated
at 60 C in a temperature controlled bath for 48 hours.
Then, the solution was filtered to separate off cake. The
cake was dried at 110 C for 24 hours, and thus,
antibacterial capsules having a mean particle size of 3
micron meter and encapsulated by porous alumina were
obtained.
The antibacterial porous inorganic capsules were
admixed with polyurethane binder, the quantity of the
capsule being 5 % of the latter, and the obtained binder
were used to coat the inner sides of a vessel made of
stainless steel. After six months from pouring water in the
vessel, no contamination due to discoloration occurred. In
order to examine the antibacterial effects to the water
poured in the vessel, l.~ x 106 of wate~ mo1d was
inoculated, and the level was lowered to less than 1 x 102
one day after. Accordingly, antibacterial effects were
confirmed.
<Example 5>
2 ~
-- 19 --
50 g of NOV~RON AG300 (antibacterial zirconium, the
products by TOAGOSEI CHEMICAL INDUSTRY CO., Ltd.) was added
to a solution, wherein 204 g of tri-isopropyl oxide
aluminum, Al(OC3H7)3 was dissolved in 150 milliliter of
isopropyl alcohol, and dispersed therein for 10 minutes by
means of an ultrasonic dispersion mixer. Then, after adding
60 milliliter of 0.2 N hydrochloride acid to the solution,
the solution was heated at 60 C in a temperature controlled
bath for 30 hours. Then, the solution was filtered to
separate off cake. The cake was washed with water, and
dried at 110 C for 24 hours, and thus, antibacterial
capsules containing antibacterial zirconium, having a mean
particle size of 2 micron meter and encapsulated by porous
alumina were obtained.
<Example 6>
10 g of silver oxide, 25 g of zinc oxide and 5 g of
copper sulfide were mixed, and were added to a solution,
wherein 0.2 g of caustic soda was dissolved in 40 g of
water, to form slurry. Then, the slurry was added with
stirring to 180 cc of an aqueous solution of sodium silicate
(6.5 moles/liter) and was subjected to a treatment by
ultrasonic. 600 cc of mixture was added to the dispersion.
The mixture contained normal-hexane and cyclo-hexane at the
mixing ratio of 1:1 and also contained 15 g/liter of
polyoxyethylene sorbitan trioleate. Then, the mixture and
dispersion were stirred together for 1 minute at 6000 rpm to
make W/O emulsion. One liter of ammonium bicarbonate (1.5
moles/liter) was added to the W/O emulsion. They were
stirred for 30 minutes at room ~emperature to react with
each other. Then, they were filtered to separate off cake.
The cake was washed with water, cleaned with ethanol, and
dried for 24 hours at 110 C. Thus, 110 g of antibacterial
porous inorganic capsules enclosing therewith silver oxide,
zinc oxide and copper sulfide at a ratio of 2 : 3 : 1 and
2 0 8 ~ ~3 1 ..
- 20 -
having a mean particle size of 0.8 micron meter were
manufactured. The powder thus obtained was white.
The antibacterial porous inor~anic capsules were
admixed with coating compound essentially consisting aqueous
acrylic-epoxy resin, the quantity of the capsule being 3 %
of the solid in the coating compound, and were stirred. The
thus obtained coating compound was coated on a floor
covering material made of polyvinyl chloride in such a
manner that the coating weight of the antibacterial porous
inorganic capsules became 3 g/m2.
Methicillin-resistant Staphylococcus aureus (MRSA) was
suspended on sterilized broth and was inoculated on the
floor covering material made of polyvinyl chloride by 0.2
milliliter. The number of bacteria was about 380000. After
it was incubated at a temperature of 37 C for 18 hours, it
was taken out, and the number of the bacteria remaining on
the test piece, i.e., the floor covering material, was
measured. The remaining MRSA was zero.
<Example 7>
60 g of APACIDER- A" (antibacterial Apatite, the
product by Kabushiki Kaisha Sangi) was dispersed in a
solution wherein 117 milliliter of ethanol was added and
dissolved to 208 g of tetraethoxysilane, Si(OC2Hs)4. Then,
after adding 90 milliliter of 0.1 N ammonia water to the
solution, the solution was dispersed by means of an
ultrasonic dispersion mixer, and then, was heated at 60 C
for 24 hours. After filtering the solution, the thus
separated off cake was filtered, washed with water, and
dried at 110 C for 24 hours, and thus 120 g of
antibacterial porous inorganic capsules having particle
sizes of between 1 to 2 micron meter were obtained.
4 parts by weight of the antibacterial porous inorganic
capsules were dispersed to a solution wherein 93 parts by
weight of acetone and 3 parts by weight of cellulose acetate
2 ~ V ~....
- 21 -
flake were dissolved. The dispersion was coated on a
non-woven fabric of rayon, the weight of which was 30 g/m2,
by means of offset printing in such a manner that the
dispersion was 50 wt.% of the rayon non-woven fabric, and
the non-woven fabric was dried. The non-woven rayon fabric
was cut in a rectangular shape of 15 x 20 cm. Ten pieces of
the cut fabric were folded and stacked over each other, and
they were contained in a sealed dispenser as wet tissues for
wiping use after water was impregnated therein. A kitchen
table, on which general bacteria had been detected by a food
stamp for bacterial test for detecting general bacteria
manufactured by Nissui Pharmaceutical Kabushiki Kaisha, was
wiped by the wet tissues, and the bacterial test was again
conducted by the food stamp for bacterial test for detecting
general bacteria after one hour, and no general bacterial
were observed.
<Example 8>
50 g of ZEOMIC AJ-lON, antibacterial zeolite, the
product by Shinanen Zeomic Corporation was added to an
aqueous solution which obtained by dissolving 0.5 g of
caustic soda in 50 g of water to form slurry. Then, the
slurry was added with stirring to 180 cc of sodium silicate
(6.5 moles/liter) to form dispersion. 600 cc of mixture was
added to the dispersion. The mixture contained
normal-hexane and cyclo-hexane at the mixing ratio of 1:1
and also contained 15 g/liter of polyoxyethylene sorbitan
trioleate. Then, the dispersion and the mixture were
stirred for 1 minute at 6000 rpm to make W/O emulsion. One
liter of ammonium bicarbonate (1.5 mo:Les/liter) was added to
the W/O emulsion. They were stirred for 30 minutes at room
temperature to react with each other. Then, they were
filtered to separate off cake. The cake was washed with
water, cleaned with ethanol, and dried for 24 hours at 110
C. Thus, 90 g of antibacterial porous inorganic capsules
- 22 - 2 ~
enclosing therewith 50 % of the antibacterial zeolite and
having a mean particle size of 3 micron meter were obtained.
2 parts by weight of the antibacterial porous inorganic
capsules were dispersed into 98 parts by weight of 1.3 %
aqueous solution of polyvinyl alcohol, and the dispersion
was applied to a cotton ball of a swab in such manner that
the quantity of the applied dispersion was 50 wt.% of the
cotton ball.
Methicillin-resistant Staphylococcus aureus (MRSA) was
cultured for 24 hours using culture medium of meat extract
bouillon and was diluted with phosphate buffer to 1/1000. 5
cc of the dilution was added to 70 cc of phosphate buffer so
that the plate count per 1 cc was made 6.7 x 103, and then
the cotton ball of the swab was dipped therein, and after
cultivation for 6 hours at 25 + 5 C, the liquid with MRSA
was taken out and plate count was performed. The result
showed the decrease ratio of the bacteria was 96.7 %.
<Example 9>
120 cc of ethanol was added and dissolved to 200 g of
tetraethoxysilane, Si(OC2Hs)4, and 40 g of silver oxide was
added to the solution and dispersed therein. Then, after
adding 90 cc of 0.1 N ammonia water, the solution was
stirred for 10 minutes by means of an ultrasonic dispersion
mixer, and was heated at 60 C for 24 hours. Then, the
solution was filtered to separate off cake. The cake was
washed and dried at 110 C for 24 hours, and thus 120 g of
antibacterial porous inorganic capsules enclosing therein
the silver oxide and having particle sizes o~ between 1 to
0.5 micron meter were obtained. The powder thus obtained
was white.
The antibacterial porous inorganic capsules were
admixed with polyethylene, the quantity of the capsule being
3 % of the latter, and a sheet for wrapping use was
manufactured with the polyethylene having the antibacterial
- 23 -
porous inorganic capsules admixed therewith. Proliferation
of general bacter-a did not occur in the meat wrapped by
this sheet after the meat was left to stand at a room
temperature for four days, and the meat was of safety.
