JP4230558B2 - Antibacterial ceramics and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to antibacterial ceramics in which antibacterial components derived from plants (especially tea) are water-resistant fixed to ceramics, and a method for producing the same.
[0002]
[Prior art]
Antibacterial agents include inorganic antibacterial agents and organic antibacterial agents, but highly safe plant-derived antibacterial agents are attracting attention.
[0003]
As belonging to plant-derived antibacterial agents, tea-derived components such as tea powder, tea extract, tea catechin and tea saponin are known to have good antibacterial properties. Moreover, since these components are derived from tea that has been used for drinking since ancient times, they are extremely safe.
[0004]
One of the ways to use these plant-derived antibacterial components is to impregnate the inorganic antibacterial component in the form of a solution or dispersion into an inorganic porous product such as a ceramic product, and then dry it to obtain an inorganic porous product It is conceivable to carry an antibacterial component on the surface.
[0005]
[Problems to be solved by the invention]
However, since plant-derived antibacterial components are often water-soluble or familiar with water, antibacterial components can be eluted in a short period of time when products that carry antibacterial components are used in contact with water. There is a problem that the antibacterial property is lost.
[0006]
For example, it is easy to impregnate a plant-derived antibacterial component into an inorganic porous product such as a ceramic product. However, if the impregnated product is used in contact with water, the product can be obtained within the first few hours to one day. Most of the antibacterial components are eluted from the solution, and the effect is rapidly lost.
[0007]
Under such a background, the present invention is water-resistant and fixed regardless of the fact that a plant-derived antibacterial component is contained in ceramics, and the antibacterial component is retained over a long period of time when used in contact with water. An object of the present invention is to provide an antibacterial ceramic that slowly elutes at a limited rate and a method for producing the same.
[0008]
[Means for Solving the Problems]
The antibacterial ceramic of the present invention comprises a composite aggregate of ceramic particles (c), a polyvalent metal salt of phosphoric acid (p), a polyphenol compound antibacterial component (a) and an inorganic flocculant (s). .
[0009]
The antibacterial ceramic production method of the present invention comprises a mixture of ceramic particles (c), a polyvalent metal salt of phosphoric acid (p), a polyphenol compound antibacterial component (a), and a medium in a sol or solution form. The inorganic flocculant (s) is mixed and aggregated, and then the aggregate is heat-treated.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
[0011]
<Ceramic particles (c)>
The ceramic particle (c) is a component that becomes a skeleton of the target antibacterial ceramic and occupies a major proportion. Examples of the ceramic particles (c) include various clay minerals, oxides, composite oxides, nitrides, carbides, silicides, borides and the like, and in particular, one type such as alumina, titania, silica, zirconia, magnesia and the like. Of these, alumina or titania is particularly important.
[0012]
The ceramic particles (c) are desirably used in the form of particles as fine as possible, such as 48 mesh (0.295 mm) under, 100 mesh (0.147 mm) under, and 200 mesh (0.074 mm) under. In this case, it is preferable to use two or more kinds of particles having different average particle diameters in terms of product hardness because the packing density increases.
[0013]
< Polyvalent metal salt of phosphoric acid (p)>
Examples of the polyvalent metal salt of phosphoric acid (p), aluminum phosphate, zinc phosphate, magnesium phosphate, and phosphoric acid manganese Agerare, these are usually in the form of a hydrate or hydrate dissolved in water Used for use. In particular, aluminum phosphate is suitable. The polyvalent metal salt (p) of phosphoric acid is a component that serves to disperse the ceramic particles (c) during the mixing operation, and is also an inorganic component that has the effect of increasing the hardness of the ceramic particles (c) after heat treatment. is there.
[0014]
<Polyphenol compound antibacterial component (a)>
As the polyphenol compound antibacterial component (a), tea powder, tea extract, catechin, saponin or tannin (acid) is preferably used, and two or more of them can be used in combination.
[0015]
As the tea powder or tea extract, for example, tea powder or extract such as Ichibancha, Nibancha, Sanbancha, Fukamushi, Kabuse, etc. can be used.
[0016]
As the catechin (which includes its attribute body), a monomeric or oligomeric one is used (including theaflavin). Of particular importance as catechins are tea-derived catechin preparations with increased concentrations of catechins. The main components of tea catechin are epigallocatechin, epigallocatechin gallate, epicatechin, epicatechin gallate, etc., but it is not necessary to isolate each component, so tea catechin consisting of a mixture of these is concentrated. A preparation (particularly, containing 20% or more, preferably 25% or more) can be suitably used as it is. Since there are 30%, 50%, 60%, 70%, 80%, 90%, etc. of commercially available tea-derived catechin preparations, it is easy to obtain. In addition, since catechin is contained also in various plants other than tea including Asen medicine, the catechin derived from those plants can also be used.
[0017]
Among the saponins, tea saponins can be obtained by extracting components containing saponins from tea leaves or tea seeds using an organic solvent or water, and then repeatedly purifying them using means such as column chromatography. Tea saponins include steroidal saponins and triterpenoid saponins, and any of these can be used for the purpose of the present invention. Saponins are also found in a variety of plants other than tea, such as carrots, chixetsu carrots, soybeans, psychos, scallops, loofahs, onjis, yellow peppers, senega, bacmonds, yellowtails, chimo, gohitsu, licorice, sankirai, etc. So saponins from such plants can also be used. However, the tea-derived tea saponins described above are particularly suitable from the viewpoint of easy availability and the small amount of impurities.
[0018]
As the tannin (acid), commercially available purified tannic acid can be used, and an extract of a high tannic acid-containing natural plant containing a large amount of tannic acid such as pentaploid and gallic or semi-purified product thereof can be used as it is. it can.
[0019]
<Inorganic flocculant (s)>
As the inorganic flocculant (s), a sol-form or solution-form inorganic flocculant, particularly, a sol-form anhydrous silicic acid or a solution-form silicate (sodium silicate or potassium silicate) is preferably used. Sol-free silicic acid includes not only ordinary colloidal silica using water as a medium, but also organosilica sol using an organic solvent such as alcohol as the medium. The particle size of the silica component is submicron, and even 0.1 μm or less. It is an order. The inorganic flocculant (s) not only serves as a flocculant but also serves as a binder.
[0020]
<Manufacture of antibacterial ceramics>
In producing the antibacterial ceramic of the present invention, a mixture of ceramic particles (c), a polyvalent metal salt of phosphoric acid (p), a polyphenol compound antibacterial component (a), and a medium is mixed with a sol or solution. After mixing and aggregating the solid inorganic flocculant (s), the agglomerate is heat-treated.
[0021]
At this time, the ceramic particles (c) and the aqueous solution of the polyvalent metal salt (p) of phosphoric acid are first kneaded, further mixed with the polyphenol compound antibacterial component (a), and then the sol-form or solution-form inorganic aggregate It is desirable to heat-treat after mixing the agent (s).
[0022]
In a typical case, an aqueous solution of aluminum phosphate as an example of a polyvalent metal salt of phosphoric acid (p) is applied to ceramic particles (c) made of alumina and / or titania so as to have a viscosity equivalent to a paste paste. In addition, kneading, then mixing the polyphenol compound antibacterial component (a) in powder or as an aqueous solution or alcohol solution, and additionally mixing an aqueous solution of aluminum phosphate as necessary to adjust the pH to 3-4 To do. Subsequently, when colloidal silica colloidal liquid as an example of the inorganic flocculant (s) is mixed to bring the pH of the system to a neutral level, aggregation occurs. After the agglomerates are obtained, they are transferred to a crucible or an evaporating dish and heat-treated until they are dehydrated in a dryer or an electric furnace.
[0023]
The proportion of each component is the amount that the polyvalent metal salt of phosphoric acid (p) exerts its role, and the polyphenol compound antibacterial component (a) is the effective amount sufficient to exert its effect (antibacterial property) The inorganic flocculant (s) is used in an amount that fulfills its role. As a typical example, when the ceramic particle (c) is 100 parts by weight, the polyvalent metal salt (p) of phosphoric acid is about 0.5 to 20 parts by weight (particularly about 1 to 15 parts by weight) in solid content. ), The polyphenol compound antibacterial component (a) is about 0.01 to 10 parts by weight (especially about 0.1 to 10 parts by weight) as a crude product, and the inorganic flocculant (s) is about 0.5 to 20 parts by weight (particularly, about 10 to 10 parts by weight). Often about 1 to 15 parts by weight).
[0024]
Since an amorphous solid is obtained by heat treatment, the solid is used as a product as it is, or once pulverized to an appropriate particle size, classified as necessary to obtain a product, or pulverized Molded and heat treated to make a product.
[0025]
<Application>
The antibacterial ceramic of the present invention produced in this way is, for example, put into a water tank or a storage tank (a drinking water storage tank, a breeding tank, a bathtub, a fire prevention tank), or a water channel or a circulation water channel (drainage channel, 24 hours). It can be installed in a bath circulation system, or placed intermittently on water (water faucets, hand-washed flush toilets or water-washed parts), or used as a hydroponics material, It can be used as a filter material for gas treatment or as a building material.
[0026]
<Action>
In the antibacterial ceramic of the present invention, the ceramic particles (c) are mainly inorganic skeleton substances, and the polyvalent metal salt of phosphoric acid (p) is intended to disperse the ceramic particles (c) during production and A component that increases hardness, a polyphenol compound antibacterial component (a) is a component that exhibits safe and excellent antibacterial properties without toxicity and allergic effects, and an inorganic flocculant (s) is a component that agglomerates during production to obtain composite particles Each as a role. The action of each of these components gives a composite aggregate that is hard overall, and the polyphenol compound antibacterial component (a) is confined (waterproof and fixed), and when it comes into contact with water, the antibacterial component ( a) or the active ingredient contained therein slowly elutes over a long period of time.
[0027]
【Example】
The following examples further illustrate the invention. Hereinafter, “parts” and “%” are expressed on a weight basis.
[0028]
Example 1
<Sample preparation>
As a polyphenol compound antibacterial component (a), tea catechin (a tea-derived catechin preparation in which the total amount of epigallocatechin, epigallocatechin gallate, epicatechin and epicatechin gallate is about 30%) was prepared.
[0029]
An average particle size of 250 mesh (0.061 mm) as ceramic particles (c) 400 parts of under alumina and 100 parts of 325 mesh (0.043 mm) undermix are dry mixed, and then a polyvalent metal salt of phosphoric acid (p) As an example, 100 parts of an aqueous aluminum phosphate solution having a concentration of 20% was added and kneaded hard to obtain a paste.
[0030]
The entire amount of the kneaded paste was put in an automatic porcelain mortar, and a solution prepared by dissolving 25 parts of the above tea catechin (purity 30% product) in 50 ml of isopropanol was added and kneaded until a slurry was formed. After confirming that the pH is about 3-4, add 37.5 parts of colloidal liquid of colloidal silica (solid content 40%) as an example of the inorganic flocculant (s) to this slurry and mix to adjust the pH. It was also neutral. Since the slurry gradually aggregated, it was transferred to an evaporating dish (or crucible) while it could be handled, heated in a constant temperature dryer or an electric furnace, and dehydrated and hydrolyzed at 100 to 300 ° C.
[0031]
As a result, a hard amorphous composite agglomerate was obtained, which was finely pulverized with an automatic mortar (or ball mill) and classified with a sieve to obtain a particle having a particle size of 100 to 325 mesh.
[0032]
The composite agglomerated powder thus obtained is granulated with a granulator (malmerizer) using an inorganic binder such as colloidal silica to form a spherical body having a diameter of 8 mm. Heat treatment was performed at 40 ° C., 100 ° C. or 200 ° C. for 3 hours in an electric furnace to obtain antibacterial ceramics.
[0033]
1 kg of this sphere (antibacterial ceramic) is set in a circulating filtration device in a water tank containing 10 liters of distilled water maintained at 25 ° C., and circulated at 1 liter / min for 7 days, 1 day, 3 days and 7 days later The elution amount (the elution amount of the organic substance dissolved in water) was measured with a thermal analyzer (differential heat / thermogravimetry).
[0034]
Of the above conditions (corresponding to Nos. 4 to 6 in Table 1 below), an experiment was also conducted in the case where the addition amount of the aqueous aluminum phosphate solution and the addition amount of the colloidal solution of colloidal silica were changed. The conditions and results are shown in Table 1. In Table 1, Al ₂ O ₃ is alumina, AlPO ₄ is aluminum phosphate, c-SiO ₂ is colloidal silica, and Catec. Is tea catechin. The elution amounts in Table 1 are obtained by measuring each elution amount after immersion for 1 day instead of fresh water every day.
[0035]
[Table 1]

Type and proportion of experimental compound (part) Elution amount of hardness organic substance after granulation (%)
No. Al ₂ O ₃ AlPO ₄ c-SiO ₂ Catec. Heating temperature (kg) 1 day 3 days 7 days
1 100 6 1.5 5 40 ° C 0.7 4.65 0.34 0.01
2 100 6 1.5 5 100 ° C 3.3 0.17 0.12 0.16
Three 100 6 1.5 Five 200 ° C 3.8 0.09 0.06 0.05
4 100 4 3.0 5 40 ° C 0.9 4.58 0.37 0.05
5 100 4 3.0 5 100 ° C 2.7 0.18 0.15 0.12
6 100 Four 3.0 Five 200 ° C 3.2 0.11 0.09 0.07
7 100 2 4.5 5 40 ° C 1.1 4.66 0.31 0.03
8 100 2 4.5 5 100 ° C 2.6 0.22 0.15 0.16
9 100 2 4.5 Five 200 ° C 2.9 0.16 0.11 0.11
10 100 0 3.0 5 40 ° C 0.6 4.61 0.35 0.04
11 100 0 3.0 5 100 ° C 1.7 4.05 0.76 0.14
12 100 0 3.0 Five 200 ° C 1.9 2.96 0.62 0.45
[0036]
From Table 1, it can be seen that the elution rate of the organic matter from the sphere has the following tendency.
Focusing on the heat treatment temperature after granulation, the order is 40 ° C. >> 100 ° C.> 200 ° C. The heating rate at 40 ° C. is too high, and tea katenkin is lost early. When heated at ℃, tea catechins gradually elute into water over a long period of time.
Focusing on the blending amount of the primary aluminum phosphate, the order of 6 parts = 4 parts = 2 parts <0 parts, especially when the blending amount is 0 parts, the heating temperature is 100 ° C. or 200 ° C. However, the spill rate of tea catechins is excessive. Note that the equal (=) sign here means roughly the same level.
[0037]
Table 1 also shows that the hardness of the sphere has the following tendency.
-Focusing on the heating temperature, the order is 40 ° C << 100 ° C <200 ° C, and the hardness is insufficient with heating at 40 ° C.
Focusing on the blending amount of the primary aluminum phosphate, the order of 6 parts = 4 parts = 2 parts> 0 parts does not greatly affect the blending amount except for the case of 0 parts. Note that the equal (=) sign here means roughly the same level.
[0038]
Therefore, in this system (alumina main ingredient-tea catechin system), it is possible to obtain antibacterial ceramics with hardness and elution rate suitable for the intended use by selecting the heating temperature and the blending amount of the primary aluminum phosphate. I understand that I can do it.
[0039]
Example 2
<Sample preparation>
Using 500 parts of alumina powder, 100 parts of an aqueous solution of aluminum phosphate with a concentration of 20%, 20 parts of antibacterial component derived from tea, and 15 parts of colloidal liquid of colloidal silica (solid content 40%), A sphere was obtained. However, the heat treatment temperature was 90 ° C. As antibacterial ingredients derived from tea, deep-boiled tea powder, tea saponin (purity 50% product, powder), tea catechin (purity 30% product and 90% product, powder), tannic acid (purity 80% product), respectively 20 parts were used.
[0040]
<Antimicrobial test>
The antibacterial properties of each sample were examined under the following conditions. The results are shown in Table 2.
-Test item: Bacteria count reduction rate test-Testing organization: Requested by the Japan Spinning Inspection Association Kinki Works-Test number: 0117116
Test strain: Staphylococcus aureus ATCC 6538P
・ Test method: Based on the unified test method (tentative name).
·Test results:
Number of inoculum [A] 1.0 × 10 ⁵ log A = 5.0
Unprocessed count [B] 1.6 × 10 ⁷ log B = 7.2
(Unprocessed cloth uses standard cotton cloth)
log B-log A = 2.2> 1.5 (test valid)
Increase / decrease value = log C-log A
Increase / decrease value difference = (log B-log A)-(log C-log A)
[0041]
[Table 2]

Sample Bacteria count log C Change value Change value difference
Alumina alone 6.7 1.7 0.5
Green tea powder (deep tea) 20 parts 3.8 -1.2 3.4
20 parts of tea saponin (purity 50% product) 4.0 -1.0 3.2
Tea catechin (purity 50% product) 20 parts 3.3 -1.7 3.9
Tea catechin (90% purity product) 20 parts 3.3 -1.7 3.9
Tannic acid ( 80 % pure product) 20 parts 4.0 -1.0 3.2
(Sample is 0.2 g. Alumina alone is alumina powder used as a raw material.)
[0042]
Table 2 shows that when the antibacterial ceramic of the present invention is used, the bacterial count is 3.3 to 4.0 in logarithmic value, which is less than 1/1000 compared to that of unprocessed cloth. .
[0043]
Example 3
<Sample preparation>
400 parts of titania powder of 400 mesh or 500 parts of alumina powder of 325 mesh, 100 parts of aluminum phosphate aqueous solution with a concentration of 20%, 10 parts of antibacterial component derived from tea (however, “alumina / tea catechin (30% product) 300 ° C. in Table 3” "Only 5 parts) and colloidal silica colloid liquid (solid content 40%) 20 parts were used to obtain a spherical body of alumina or titania main component according to Example 1. As tea-derived active ingredients, green tea powder, tea saponin (purity 50% product, powder) and tea catechin (purity 30% product and 90% product, powder) were used, respectively. The heat treatment temperature was 90 ° C, 200 ° C or 300 ° C.
[0044]
<Antimicrobial test>
The antibacterial properties of each sample were examined under the following conditions. The results are shown in Table 3.
・ Test item: Bacteria count reduction rate test ・ Testing institution: Requested by the Japan Spinning Inspection Association Kinki Office ・ Test number: 020936
Test strain: Staphylococcus aureus ATCC 6538P
・ Test method: Based on the unified test method (tentative name).
·Test results:
Number of inoculated [A] 1.7 × 10 ⁴ log A = 4.2
Unprocessed count [B] 7.2 × 10 ⁶ log B = 6.9
(Unprocessed cloth uses standard cotton cloth)
log B-log A = 2.7> 1.5 (test valid)
Increase / decrease value = log C-log A
Increase / decrease value difference = (log B-log A)-(log C-log A)
[0045]
[Table 3]

Sample and heat treatment temperature Number of bacteria log C Increase / decrease value Difference
Titania alone 5.7 1.5 1.2
Titania / Green tea powder 90 ℃ 3.3 -0.9 3.6
Titania / Green tea powder 200 ℃ 3.3 -0.9 3.6
Titania / tea saponin (50% product) 90 ℃ 3.3 -0.9 3.6
Titania / tea saponin (50% product) 200 ℃ 3.3 -0.9 3.6
Titania / tea catechin (30% product) 90 ℃ 3.3 -0.9 3.6
Titania / tea catechin (30% product) 200 ℃ 3.3 -0.9 3.6
Titania / tea catechin (90% product) 90 ℃ 3.3 -0.9 3.6
Titania / tea catechin ( 90 % product) 200 ℃ 3.3 -0.9 3.6
Alumina alone 6.0 1.8 0.9
Alumina / green tea powder 200 ℃ 3.8 -0.9 3.6
Alumina / tea saponin (50% product) 200 ℃ 4.0 -0.9 3.6
Alumina / tea catechin (30% product) 200 ℃ 3.3 -0.9 3.6
Alumina / tea catechin (30% product) 300 ℃ 3.3 -0.9 3.6
Alumina / tea catechin ( 90 % product) 200 ℃ 3.3 -0.9 3.6
(Tested with a sample weight of 0.2 g. Titania or alumina alone is not heat-treated.)
[0046]
From Table 3, it can be seen that when the antibacterial ceramic of the present invention is used, the number of bacteria is 3.6 as a logarithmic value, which is one thousandth or less compared with that of the unprocessed cloth.
[0047]
【The invention's effect】
According to the present invention, each component affects each other, and a product having hardness as a whole is obtained, and the polyphenol compound antibacterial component is confined, and as a result, the antibacterial component is contained in the ceramic. Regardless of its preferred water-resistant fixation, the antibacterial components slowly elute at a limited rate over a long period of time when used in contact with water.

Claims (3)

An antibacterial ceramic comprising a composite aggregate of ceramic particles (c), a polyvalent metal salt of phosphoric acid (p), a polyphenol compound antibacterial component (a) and an inorganic flocculant (s). A mixture of ceramic particles (c), polyvalent metal salt of phosphoric acid (p), polyphenolic antibacterial component (a), and medium is mixed with a sol-like or solution-like inorganic flocculant (s) for aggregation. And then a heat treatment of the aggregate. The process according to claim 2, wherein the inorganic flocculant (s) is sol-form silicic anhydride or solution-form silicate.