JPH11255555A - Antimicrobial ceramic and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide antimicrobial ceramics in which antimicrobial ingredients extracted from plants are included and moreover the antimicrobial ingredients are immobilized for acquiring water resistance and therefore the antimicrobial ingredients slowly elute at a limited rate for a long term when used in a state contacted with water, and to provide a method for producing the same ceramics. SOLUTION: This antimicrobial ceramics are prepared by compounding a mixture consisting of (C) ceramic particles (e.g. alumina or titania), (P) an inorganic sintering auxiliry such as alminium phosphate, (A) polyphenol compound-based antimicrobial component and (B) a medium, with (S) an inorganic flocculant (e.g. colloidal silica) being a sol or a solution and by making the compounded system agglomerate, followed by heat treatment of the agglomerate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial ceramic in which an antibacterial component derived from a plant (particularly tea) is fixed to a ceramic in a water-resistant manner, and a method for producing the same.

[0002]

2. Description of the Related Art As antibacterial agents, there are inorganic antibacterial agents and organic antibacterial agents, and plant-derived antibacterial agents having high safety are attracting attention.

It is known that tea-derived components such as tea powder, tea extract, tea catechin and tea saponin have good antibacterial properties as belonging to plant-derived antibacterial agents. In addition, since these components are derived from tea that has been used for drinking since ancient times, they are extremely safe.

One of the uses of these plant-derived antimicrobial components is to impregnate the antimicrobial components in the form of a solution or dispersion into an inorganic porous product such as a ceramic product and then dry the resulting product to obtain an inorganic component. It is conceivable to carry an antimicrobial component on the porous product.

[0005]

However, since plant-derived antibacterial components are often water-soluble or water-compatible, a product carrying an antibacterial component is exposed to water for a short period of time. There is a problem that the antibacterial component is eluted in the middle and the antibacterial property is lost.

For example, it is easy to impregnate a plant-derived antibacterial component into an inorganic porous product such as a ceramic product, but if the impregnated material is used in contact with water, the first several hours to one day To a large extent, most of the antimicrobial components are eluted from the product and the effect is rapidly lost.

[0007] Under such a background, the present invention provides a water-resistant fixation of a plant-derived antibacterial component irrespective of the fact that the ceramic component is contained in the ceramic, and a long-term antibacterial effect when used in contact with water. It is an object of the present invention to provide an antibacterial ceramic in which a conductive component slowly elutes at a limited ratio and a method for producing the same.

[0008]

The antibacterial ceramic of the present invention comprises ceramic particles (c), an inorganic sintering aid (p),
It comprises a composite aggregate of a polyphenol compound antibacterial component (a) and an inorganic coagulant (s).

The method for producing the antibacterial ceramic of the present invention comprises:
A mixture consisting of ceramic particles (c), inorganic sintering aid (p), polyphenolic compound antibacterial component (a) and medium was mixed with sol or solution inorganic coagulant (s) and agglomerated. Thereafter, the aggregate is subjected to a heat treatment.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

<Ceramic Particle (c)> The ceramic particle (c) is a component that constitutes the skeleton of the antibacterial ceramic as the target and occupies a major proportion. Examples of the ceramic particles (c) include various types of clay minerals, oxides, composite oxides, nitrides, carbides, silicides, borides, and the like, and in particular, alumina, titania, silica, zirconia, magnesia, etc. As described above, alumina or titania is particularly important.

The ceramic particles (c) are 48 mesh
(0.295 mm) under, 100 mesh (0.147 mm) under, and more preferably 200 mesh (0.074 mm) under as fine as possible. In this case, it is preferable to use two or more kinds of particles having different average particle diameters in combination from the viewpoint of the product hardness since the packing density becomes large.

<Inorganic sintering aid (p)> Inorganic sintering aid
Examples of (p) include polyvalent metal salts of phosphoric acid such as aluminum phosphate, zinc phosphate, magnesium phosphate, and manganese phosphate, which are usually obtained by dissolving a hydrate or hydrate in water. Serve for use. Particularly, aluminum phosphate is preferred. The inorganic sintering aid (p) is a component that plays a role in dispersing the ceramic particles (c) during the mixing operation, and is also an inorganic component that has the function of increasing the hardness of the ceramic particles (c) after heat treatment.

<Polyphenol compound antibacterial component (a)
〉 Polyphenol compound antibacterial component (a)
Tea powder, tea extract, catechin, saponin or tannin (acid) are preferably used, and two or more of them can be used in combination.

As the tea powder or tea extract, for example, tea powder or extract such as Ichiban-cha, second-cha, or third-cha, deep-brushed tea, and capsushi can be used.

As the catechin (including its attribute form), a monomer form or an oligomer form is used (including theaflavin). Of particular importance as catechins are tea-derived catechin preparations with an increased catechin concentration. The main components of tea catechin are epigallocatechin, epigallocatechin gallate, epicatechin, epicatechin gallate, etc., but it is not necessary to isolate it into individual components, so it contains tea catechin consisting of a mixture of these richly Preparations (particularly those containing 20% or more, preferably 25% or more) can be suitably used as they are. 30% for commercially available tea-derived catechin preparations
Product, 50% product, 60% product, 70% product, 80% product, 90%
Since there is a product, it is easy to obtain it. Since catechin is contained in various plants other than tea, such as Asenyaku, catechin derived from those plants can also be used.

Of the saponins, tea saponin can be obtained by extracting a saponin-containing component from tea leaves or tea seeds using an organic solvent or water, and then repeatedly purifying it using a means such as column chromatography. In tea saponin,
There are steroid saponins, triterpenoid saponins and the like, and any of them can be used for the purpose of the present invention. Saponin is also contained in a variety of plants other than tea, such as carrots, carrots, soybeans, soybeans, psycho, amachadul, luffa, onji, kyokyo, senega, bacmondou, mokutsu, timo, gossip, licorice, sankirai, etc. Thus, saponins from such plants can also be used. However, the above-mentioned tea-derived tea saponins are particularly preferred in view of the availability and the small amount of impurities.

As the tannin (acid), a 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 quintet or gallic, or a semi-purified product thereof is used as it is. It can also be used.

<Inorganic flocculant (s)> As the inorganic flocculant (s), a sol or solution inorganic flocculant, in particular, sol silicic anhydride or solution silicate (sodium silicate) And potassium silicate) are preferably used. Sol-based silicic anhydride includes ordinary colloidal silica using water as a medium, and organosilica sol using an organic solvent such as alcohol as a medium.The particle size of the silica component is submicron, and further 0.1 μm or less. It is an order. The inorganic flocculant (s) plays a role not only as a flocculant but also as a binder.

<Manufacture of antibacterial ceramics> In manufacturing the antibacterial ceramics of the present invention, the ceramic particles (c), the inorganic sintering aid (p), the polyphenol compound antibacterial component (a) and the medium are used. The resulting mixture is mixed with a sol-form or solution-form inorganic coagulant (s) to coagulate and then heat-treated the coagulate.

At this time, first, the ceramic particles (c)
And an aqueous solution of an inorganic sintering aid (p), and a polyphenolic compound-based antimicrobial component (a), and then a sol or solution inorganic coagulant (s). It is desirable to do so.

In a typical case, an aqueous solution of aluminum phosphate as an example of an inorganic sintering aid (p) is added to ceramic particles (c) made of alumina or / and titania so as to have a viscosity similar to that of a paste. Kneaded in addition to the polyphenol compound antibacterial component (a)
Is mixed as a powder or as an aqueous solution or an alcohol solution, and if necessary, an aqueous solution of aluminum phosphate is additionally mixed to adjust the pH to 3 to 4. Then, when a colloidal solution of colloidal silica as an example of the inorganic flocculant (s) is mixed to bring the pH of the system to a neutral level, flocculation occurs. After obtaining the aggregates, the aggregates are transferred to a crucible or an evaporating dish and subjected to heat treatment in a dryer or an electric furnace until they are dehydrated.

The proportion of each component is such that the inorganic sintering aid (p) exerts its role and the polyphenol compound antibacterial component (a) is an effective amount sufficient to exhibit its effect (antibacterial). The inorganic coagulant (s) is used in such an amount as to exert its role. To give a typical example, ceramic particles (c)
When the amount is 00 parts by weight, the inorganic sintering aid (p) is
About 0.5 to 20 parts by weight (especially about 1 to 15 parts by weight), the polyphenol compound-based antibacterial component (a) is 0.1% as a crude product
It is often about 01 to 10 parts by weight (particularly about 0.1 to 10 parts by weight), and the inorganic coagulant (s) is about 0.5 to 20 parts by weight (particularly about 1 to 15 parts by weight) in solid content.

Since an amorphous solid can be obtained by the heat treatment, the solid may be used as a product as it is, or may be once pulverized to an appropriate particle size and classified if necessary to obtain a product.
The pulverized product is granulated or molded and heat-treated to obtain a product.

<Applications> The antibacterial ceramics of the present invention thus manufactured may be put into, for example, a water tank or a storage tank (a drinking water storage tank, a breeding tank, a bathtub, a fire protection tank), or may be placed in a waterway or a circulation waterway. (Drainage channel, bath circulation system for 24 hours), place it in a place where water is intermittently applied (faucet of tap water, a place where hand washing or flush water of a flush toilet is applied), or It can be used as a material, used as a filter material for gas treatment, or used as a building material.

<Function> In the antibacterial ceramic of the present invention, the ceramic particles (c) mainly disperse the ceramic particles (c) at the time of production, while the inorganic sintering aid (p) mainly disperses the ceramic particles (c). In addition, a component that increases the hardness of the final product, a polyphenol compound antibacterial component (a) is a component that exhibits safe and excellent antibacterial properties without toxicity and allergic effects, and an inorganic coagulant (s) coagulates during production and combines Each plays a role as a component for obtaining particles. By the action of each of these components, a composite aggregate having hardness as a whole is obtained, and the polyphenolic compound-based antibacterial component (a) is confined (waterproof and fixed), and the antibacterial component ( a) or the active ingredient contained therein elutes slowly over a long period of time.

[0027]

The present invention will be further described with reference to the following examples. Hereinafter, “parts” and “%” are expressed on a weight basis.

Example 1 <Preparation of sample> Antibacterial component (a) of polyphenol compound type
As a tea catechin (epigallocatechin, epigallocatechin gallate, epicatechin and a tea-derived catechin preparation having a total amount of epicatechin gallate of about 30%).

Average particle size 2 as ceramic particles (c)
After dry mixing 400 parts of 50 mesh (0.061 mm) under alumina and 100 parts of 325 mesh (0.043 mm) under alumina, a 20% aqueous solution of aluminum phosphate as an example of an inorganic sintering aid (p) The mixture was kneaded hard while adding 100 parts to obtain a paste.

The whole amount of the kneaded paste was put into an automatic porcelain mortar, and a solution prepared by dissolving 25 parts of the above tea catechin (purity 30%) in 50 ml of isopropanol was added and kneaded until a slurry was formed. After confirming that the pH is about 3 to 4, a colloidal solution of colloidal silica as an example of the inorganic coagulant (s) (solid content 40%) is added to the slurry.
%) Was added and mixed to bring the pH to neutral. Since the slurry gradually aggregated, it was transferred to an evaporating dish (or crucible) while handling was possible, heated in a thermostatic dryer or an electric furnace, and dehydrated and hydrolyzed at 100 to 300 ° C.

As a result, a hard amorphous composite agglomerate was obtained, which was pulverized in an automatic mortar (or ball mill) and classified with a sieve to obtain a particle having a particle size of 100 to 325 mesh.

The thus obtained composite agglomerate powder 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, and then is subjected to constant temperature. Dryer or electric furnace at 40 ℃, 100
Heat treatment was performed at 300C or 200C for 3 hours to obtain an antibacterial ceramic.

1 kg of this spherical body (antibacterial ceramic)
Is set in a circulating filtration device in a water tank containing 10 liters of distilled water kept at 25 ° C., circulating at 1 liter / min for 7 days, and elution amounts after 1 day, 3 days and 7 days (dissolution in water The amount of the dissolved organic substance) was measured by a thermal analyzer (differential heat / thermogravimetry).

The above conditions (see Table 1 for Nos. 4 to 6)
The amount of aluminum phosphate aqueous solution
When the amount of colloidal silica colloid solution is changed
Was also tested. Table 1 shows the conditions and results. table
1 in Al_TwoO_Three Is alumina, AlPO _Four Is aluminum phosphate
System, c-SiO_TwoIs colloidal silica, Catec. Is tea catechin
is there. The elution amount in Table 1 was changed to fresh water every day and soaked for one day.
The amount of each elution after immersion was measured.

[0035]

[Table 1] Type and mix ratio of experimental blend (part) Hardness after granulation Elution amount of organic matter (%) 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 1.55 100 ° C 3.3 0.17 0.12 0.16 3 100 6 1.5 5 200 ° 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 4 3.0 5 200 ° 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 5 200 ° 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 5 200 ° C 1.9 2.96 0.62 0.45

From Table 1, it can be seen that there is the following tendency in the elution rate of organic substances from the sphere. -Focusing on the heat treatment temperature after granulation, 40 ° C >> 10
0 ° C.> 200 ° C. in order. When heating at 40 ° C., the elution rate is too fast and tea cattenkin is lost early. However, when heating at 100 ° C. or 200 ° C., tea catechin gradually elutes into water for a long time. -Focusing on the amount of the aluminum monophosphate, the order is 6 parts = 4 parts = 2 parts <0 parts. In particular, when the amount is 0 parts, the heating temperature is 100 ° C. or 200 ° C. Also, the outflow rate of tea catechin is excessive. Equal (=)
The symbol here means generally at the same level.

Further, from Table 1, regarding the hardness of the spherical body,
It can be seen that there is the following tendency. -Focusing on the heating temperature, 40 ° C << 100 ° C <200
° C, and heating at 40 ° C results in insufficient hardness. Focusing on the blending amount of aluminum monophosphate, the order is 6 parts = 4 parts = 2 parts> 0 parts, and does not significantly affect the blending amount except for the case of 0 parts. Note that the equal (=) symbol here means that the levels are substantially the same.

Accordingly, in this system (alumina base material-tea catechin system), antibacterial ceramics having hardness and elution rate suitable for the intended use can be obtained by selecting the heating temperature and the amount of the aluminum monophosphate. You can see that it can be done.

Example 2 <Preparation of Sample> 500 parts of alumina powder, 100 parts of a 20% aqueous solution of aluminum phosphate, 20 parts of an antibacterial component derived from tea, and a colloidal solution of colloidal silica (solid content: 40 parts)
%) To obtain spherical alumina base material in the same manner as in Example 1 using 15 parts. However, the heat treatment temperature was 90 ° C. As the antibacterial components derived from tea, deep seaweed tea powder, tea saponin (purity 50% product, powder), tea catechin (purity 30% and 90% product, powder), tannic acid (purity 80% product) respectively 20 parts were used.

<Antibacterial test> The antibacterial properties of each sample were examined under the following conditions. Table 2 shows the results.・ Test item: Bacteria count reduction test ・ Testing organization: Requested from the Kinki Plant of the Japan Spinning Inspection Association ・ Test number: 017116 ・ Test strain: Staphylococcus aureus A
TCC 6538P ・ Test method: Use the unified test method (tentative name).・ Test results: Inoculation count [A] 1.0 × 10 ⁵ log A = 5.0 Unprocessed cloth count [B] 1.6 × 10 ⁷ log B = 7.2 (Standard cotton cloth is used for unprocessed cloth) log B-log A = 2.2> 1.5 (Test is valid) Change = log C-log A Change = (log B-log A)-(log C-log A)

[0041]

[Table 2] Sample Bacterial count log C Increase / decrease Increase / decrease difference Alumina alone 6.7 1.7 0.5 20 parts green tea powder (deep mushroom tea) 3.8 -1.2 3.4 20 parts tea saponin (purity 50%) 4.0 -1.0 3.2 Tea catechin (purity 50%) ) 20 parts 3.3 -1.7 3.9 Tea catechin (purity 90% product) 20 parts 3.3 -1.7 3.9 Tannic acid (purity 80% product) 20 parts 4.0 -1.0 3.2 (Sample 0.2 g. Alumina alone was used as a raw material.) Alumina powder.)

From Table 2, when the antibacterial ceramic of the present invention is used, the number of bacteria is 3.3 to 4.0 in logarithmic value, which is 1/1000 or less as compared with that of the unprocessed cloth. You can see that.

Example 3 <Preparation of Sample> 400 mesh titania powder or 3
500 parts of 25-mesh alumina powder, 100 parts of a 20% aluminum phosphate aqueous solution, and 10 parts of tea-derived antibacterial components (provided that “alumina / tea catechin (30%
Article 5) (300 ° C. only) and 20 parts of colloidal silica colloid (solid content: 40%) were used to obtain spherical alumina or titania bases according to Example 1. Green tea powder, tea saponin (purity 50%)
Catechin (purity 30% and 90%, powder). The heat treatment temperature is 90 ° C, 20
0 ° C. or 300 ° C.

<Antibacterial Test> The antibacterial properties of each sample were examined under the following conditions. Table 3 shows the results.・ Test item: Bacteria reduction rate test ・ Testing organization: Requested to the Kinki Plant of the Japan Spinning Inspection Association ・ Test number: 020936 ・ Test strain: Staphylococcus aureus A
TCC 6538P ・ Test method: Use the unified test method (tentative name). -Test results: Inoculation count [A] 1.7 × 10 ⁴ log A = 4.2 Unprocessed cloth 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 is valid) Change = log C-log A Change = (log B-log A)-(log C-log A)

[0045]

[Table 3] Sample and heat treatment temperature Bacterial count log C Increase / decrease value 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 (50 200 ℃ 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 tested at -0.9 3.6 (sample weight 0.2 g. titania or alumina alone heat treatment And.)

As shown in Table 3, when the antibacterial ceramic of the present invention was used, the number of bacteria was 3.6 in logarithmic value, which was less than one thousandth of that of untreated cloth. I understand.

[0047]

According to the present invention, the components influence each other to obtain a product having hardness as a whole, and the polyphenol compound-based antibacterial component is confined. As a result, the antibacterial component is converted into ceramics. Regardless of whether or not it is contained, the water-resistant fixation is preferable, and when used in contact with water, the antibacterial component slowly elutes at a limited ratio over a long period of time.

Claims (3)

[Claims] 1. Ceramic particles (c), inorganic sintering aid
(p) An antimicrobial ceramic comprising a composite aggregate of an antimicrobial component (a) of a polyphenol compound type and an inorganic coagulant (s). 2. Ceramic particles (c), inorganic sintering aid
(p) mixing a sol- or solution-type inorganic coagulant (s) with a mixture of a polyphenol compound-based antibacterial component (a) and a medium to cause coagulation, and then subjecting the coagulated material to heat treatment. Characteristic manufacturing method of antibacterial ceramics. 3. The inorganic sintering aid (p) is a polyvalent metal salt of phosphoric acid, and the inorganic flocculant (s) is a sol-form silicic anhydride or a solution-form silicate. Manufacturing method.