JP2559125B2 - Method for producing antibacterial zeolite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an antibacterial zeolite. More specifically, the present invention provides a novel method for producing an antibacterial zeolite having excellent dispersibility and high purity. In addition, the present invention also provides a method for producing an antibacterial zeolite composed of fine powder suitable for a so-called filler, which is added for the purpose of antibacterial body such as polymer.

In the production of a so-called antibacterial zeolite having sterilization or antibacterial activity, an ion exchange reaction between a metal ion having a bactericidal action and zeolite is carried out in an aqueous solution, and the former is bound and retained in the matrix of the latter to be prepared. Is customary. In this case, depending on the conditions of the ion exchange reaction, basic salts or oxides of antibacterial metal are deposited on the solid phase of the antibacterial zeolite obtained, and the presence of these impurities not only reduces the purity of the antibacterial zeolite. , A phenomenon that deteriorates its antibacterial performance is seen. Further, the antibacterial zeolite particles produced by the ion exchange reaction in the aqueous phase have a drawback that they are likely to aggregate. The present inventor has diligently studied to prevent the above-mentioned unfavorable phenomenon seen in the case of conversion to an antibacterial zeolite, and as a result, under the adjusted conditions, the solvent-water system ion exchange reaction is dispersed. The present invention has been completed by finding that it is very effective for obtaining an antibacterial zeolite having high properties and high purity. The details of the present invention will be described below.

Reacting one or more metal ions selected from the group of antibacterial metals consisting of silver, copper, zinc, tin, lead, bismuth, iron, and chromium with zeolite in an alcohol-water mixture having a pH of 6 or less. The present invention provides a method for producing an antibacterial zeolite in which 90% or less of the theoretical value of the ion exchange capacity of the zeolite is replaced with an antibacterial metal.

The zeolite used as a raw material in the present invention may be either natural or synthetic. The above zeolite has the general formula It is a crystalline aluminosilicate having a three-dimensional structure represented by. In the present invention, the ion-exchangeable metal M is partially replaced with one or more metal ions selected from the above-mentioned antibacterial metal group to prepare an antibacterial zeolite. In this case, it is important to suppress the substitution rate of the antibacterial metal to 90% or less of the theoretical value of the ion exchange capacity of the zeolite in order to prevent the precipitation of impurities such as basic salts on the solid phase of the antibacterial zeolite. X in the above general formula
And y represent the coefficients of metal oxide and silicon dioxide, respectively, and z represents the number of molecules of water of crystallization in the zeolite.

Suitable natural zeolites used in the present invention include chiabasite (EC5meq / g), mordenite (EC2.6meq / g),
Examples include erionite (EC3.8meq / g) and clinoptilolite (EC2.6meq / g). However, EC indicates the theoretical exchange capacity value of zeolite. On the other hand, as the synthetic zeolite, for example, A-type zeolite (EC7meq / g), X-type zeolite (EC6.4meq / g), Y-type zeolite (EC5meq / g)
g) and the like are preferred. The natural and synthetic zeolites exemplified are porous and have a large specific surface area and
The EC value also has a favorable value. When preparing the antibacterial zeolite of the present invention, it is necessary to suppress the antibacterial metal holding amount to 90% or less of EC for the reason described above.

Now, the above-mentioned natural or synthetic zeolite is reacted in the form of fine powder with one or more antibacterial metal ions selected from the aforementioned antibacterial metal group in an alcohol-water mixed solution having a pH of 6 or less. An antibacterial zeolite is prepared by replacing 90% or less of EC of the zeolite with an antibacterial metal.
For example, Ag ⁺ and zeolite (sodium-type A-type zeolite NaZ) are ion-exchanged (at room temperature to high temperature) in an alcohol (ethyl alcohol or methyl alcohol) -water mixture having a pH of 6 or less, and part of Na is partially converted to Ag ⁺ . By substitution, antibacterial zeolite NaAgZ (however, Ag content is 90% or less of EC) is prepared. In addition, Na combined with antibacterial metal ions
AgCuZ (however, the content of Ag and Cu is 90% or less of EC) is also the same as the previous example, and the alcohol that holds Ag ⁺ -Cu ²⁺ and NaZ at pH 6 or less-
It is of course possible to prepare by reacting in a water mixture. As described above, the pH of the liquid phase at the time of ion exchange is desirably suppressed to pH 6 or less, and the acidity of the liquid phase is adjusted to a preferable state by the antibacterial metal ion and the type of zeolite used. The amount of alcohol used in carrying out the above-mentioned ion exchange is governed by the type of antibacterial metal ion, but for example, tin-based antibacterial zeolite [Example: NaSn (II)
Z] At the time of preparation, it is desirable to maintain the solution in an alcohol-containing liquid of at least 20% or more and adjust the pH to 4 or less. Further, in the production of the antibacterial zeolite of the present invention, it is important to keep the amount of the antibacterial metal used in the zeolite matrix to be 90% or less of EC. By adjusting the pH of the reaction liquid phase, the alcohol content, and the amount of the antibacterial metal retained in the zeolite matrix, as described above, the purity of the finally obtained antibacterial zeolite is increased, and It has been confirmed that it is possible to prevent the surface from being contaminated with an impure component such as a basic salt generated by a side reaction to a minimum. Contamination of the antibacterial zeolite by impure components causes a decrease in its original antibacterial activity (Table-
1 of Example-2 and Comparative Example-2 or Example-3 and Comparative Example-2).

When a NaBZ-type antibacterial zeolite is prepared by a method different from the present invention, for example, using an antibacterial metal ion (B) and NaZ powder and utilizing ion exchange in an aqueous phase, the B content and pH in NaBZ As the amount increases, part of B in the solid phase of antibacterial zeolite is hydrolyzed to form an insoluble basic salt [eg, basic salt of copper (II) or Sn (II)] and oxide ( Example: AgO, CuO, SnO, SnO ₂ ) etc. tend to increase. Since these precipitates are deposited on the surface of the prepared NaBZ, they tend to reduce the original antibacterial activity and bactericidal activity of NaBZ. Therefore, it is important to suppress the precipitation of the insoluble impurities to the minimum in order to maximize the original antibacterial function of the antibacterial zeolite. In the ion exchange, when the NaZ to be used is replaced with B up to the saturation value of EC, that is, when it is converted into the BZ type, the production rate of the insoluble compound tends to increase. In order to minimize the precipitation of such insoluble compounds on the surface of antibacterial zeolite, as in the present application, the amount of M retained is kept below 90% of the EC of NaZ material, and the ion exchange reaction is prevented. It is important to carry out the treatment in an acidic region of alcohol-water system.

The starting material of the zeolite used in the method for producing an antibacterial zeolite of the present invention has a particle size of 10 μm or less for alcohol-
It is preferable because it increases the rate of ion exchange reaction in the water mixed solution. If the particle size of the zeolite is too large, the conversion time to the antibacterial zeolite becomes longer, which is not a good idea. In the production of the antibacterial zeolite of the present invention, as described above, the conversion to the antibacterial zeolite is carried out in an alcohol-water system having a pH of 6 or less, but it is produced due to the presence of a polar solvent such as alcohol. There is an advantage that the aggregation between the antibacterial zeolite particles can be extremely minimized. Therefore, according to the method of the present invention, it is possible to obtain antibacterial zeolite fine particles having a high dispersibility, which simplifies the pulverization process and the like when the antibacterial zeolite fine particles are used in a polymer filler. It leads to energy saving.

The ion exchange capacity (E
90% or less of the theoretical value of C) is obtained by obtaining an antibacterial zeolite in which 90% or less of the theoretical value is substituted with the above-mentioned antibacterial metal, and this is filtered, and then an alcohol-water mixed solution or alcohol, or both solutions are used together The present invention further provides a method for producing an antibacterial zeolite, which comprises washed, and subsequently dried, fine powder having a high dispersibility. That is, by performing the above-mentioned method to wash the antibacterial zeolite to remove excess antibacterial metal ions and then to dry it, hydrolysis of the antibacterial zeolite itself caused in the treatment step and aggregation thereof can be suppressed. As a result, a highly pure antibacterial zeolite powder, which is the final target product of the original surface and is highly dispersed, can be obtained.

The antibacterial zeolite obtained in the present invention, if necessary,
Further pulverized to adjust particle size (often 10 μm
Adjusted below). The particle size of the antibacterial zeolite depends on the purpose for which it is used. For example, when the antibacterial zeolite obtained in the present invention is used by kneading into fibers such as nylon and polyester for the purpose of antibacterial or sterilization and deodorization, its particle size is preferably 1.5 μm or less, and 0.1 to 1 μm.
The range of m is the most preferable range. Further, when antibacterial zeolite is added to a polymer such as polyethylene, polypropylene, polyvinyl chloride, polyvinyldene chloride, epoxy resin, etc., the desirable particle size is 5 μm at maximum and within the range of 0.1 to 3 μm. Is the most preferred range. Further, when used as an antibacterial filler in the field of pigments, paints, etc., it is desired that the antibacterial zeolite obtained in the present invention has a particle size of 10 μm or less and is excellent in dispersibility.

When the powder of the antibacterial zeolite obtained in the present invention is added as an antibacterial filler to the above-mentioned high molecular weight product, its dry powder (100 ° C to 110 ° C) is further heated in a temperature range of 130 ° C to 350 ° C. Then, the water content therein is usually adjusted to 6% or less. If the above heating operation is carried out under reduced pressure, the water of crystallization is easily removed, and it is easy to reduce it to 3% or less. For example, if the antibacterial zeolite fine powder (dry product) obtained by the method of the present invention is treated under reduced pressure at around 210 ° C to 220 ° C, it is easy to keep the water content therein at 0.3% or less.

Example 1 This example describes an example in which a NaAgZ type antibacterial zeolite was produced based on the method for producing an antibacterial zeolite of the present invention. Dry powder of A-type synthetic zeolite [1.09Na ₂ O ・ Al ₂ O ₃・ 1.85SiO ₂・ xH ₂ O: Dav = 3.8 μm; EC =
7.76 meq / g (anhydrous basis)] to about 250 g, about 500 ml of 0.11 MAgNO ₃ solution [C ₂ H ₅ OH (40 v / o) -H ₂ O (60 v / o)] was added. Dilute nitric acid was gradually added while keeping the above mixture under stirring, and finally the pH of the mixed solution was maintained at 2.7. Next, the mixed slurry liquid was kept under stirring at 40 ° C. for 3 hours to carry out an ion exchange reaction. The obtained reaction product was filtered, and then a C ₂ H ₅ OH-containing liquid [C ₂ H ₅ OH (50 v / o) -H ₂ O (50 v /
o)]. The washed solid phase is finally 100 ℃ ~
Fine powder of NaAgZ dried at 110 ℃, then crushed 24
1 g [Ag = 2.7% (anhydrous basis); Dav = 3.9 μm] was obtained.

The silver content in the NaAgZ powder obtained in this example corresponds to 90% or less of the theoretical exchange capacity of NaZ used. The purity of this product was extremely high, and no precipitation of basic silver salts or oxides was confirmed. Also, the average particle size of the fine powder of NaAgZ Dav = 3.9μ
m, and almost no agglomeration between particles is observed in the manufacturing process of the antibacterial zeolite. (Dav of NaZ material = 3.8 μm).

Comparative Example 1 This example describes a case where NaAgZ type antibacterial zeolite was produced by performing ion exchange in an aqueous solution. About 500 g of dry powder of the same type A synthetic zeolite as in Example-1 was added with about 500 ml of 0.11 MAgNO ₃ (aqueous solution), and diluted nitric acid was gradually added to the resulting mixture to adjust the pH of the solution to 7. Was done. Next, the mixed slurry liquid was kept under stirring at 40 ° C. for 3 hours to carry out an ion exchange reaction. The product obtained was filtered and then washed with water. 100 ° C to 110 ° C for products that have been washed with water
238g [Ag = 2.9%]
(Anhydrous standard); Dav = 4.5 μm] was obtained.

In the NaAgZ powder obtained in this comparative example, a basic salt or oxide of silver (see X-ray diffraction results in FIGS. 1A and B) coexist.

Compared to both Example 1 and Comparative Example 1, the product obtained by the method for producing an antibacterial zeolite according to the present invention has a higher purity and is effective in preventing the formation of basic salts and oxides. Is clear. Further, comparing the Dav values of the NaAgZ fine powders obtained by both methods shows that the method of the present invention tends to further reduce the aggregation between the antibacterial zeolite particles.

Example 2 This example shows an example of producing a NaCuZ type antibacterial zeolite based on the method for producing an antibacterial zeolite of the present invention. A dry powder of the same type A synthetic zeolite as in Example 1 (about 250 g) was used with 0.49 M CuSO ₄ solution [CH ₃ OH (25 v / o)].
-H ₂ O (75v / o)] of about 500ml was added. Dilute sulfuric acid was gradually added while the above mixture was kept under stirring, and the pH of the mixed solution was finally kept at 3.5. Next, the mixed slurry liquid is 25 ℃
The ion exchange reaction was carried out by stirring for 3 hours in the vicinity.
The reaction product obtained was filtered, and then a CH ₃ OH-containing liquid [C
H ₃ OH (50 v / o) -H ₂ O (50 v / o)] The washed solid phase was finally dried at 100 ° C-110 ° C and then crushed to obtain a fine powder of NaCuZ. 236 g [Cu = 6.7% (anhydrous basis); Dav = 3.9 μm] were obtained.

The copper content in the NaCuZ powder obtained in this example corresponds to a theoretical exchange capacity of 90% or less of NaZ used, its purity is extremely high, and precipitation of basic salts or oxides of copper is not confirmed at all. It was Further, the fine powder of NaCuZ had Dav = 3.9 μm, and almost no aggregation between particles was observed in the manufacturing process of the antibacterial zeolite (Dav = 3.8 μm of NaZ material).

Comparative Example 2 This example describes the case of producing NaCuZ type antibacterial zeolite by performing ion exchange in an aqueous solution. About 500 g of a 0.5 M CuSO ₄ solution (aqueous solution) was added to about 250 g of the same dry powder of the same type A synthetic zeolite as in Example-2. Dilute sulfuric acid was added keeping the mixture under stirring and the pH of the mixture was finally kept at 4.5. Next, the mixed slurry liquid was stirred at around 25 ° C. for 3 hours to carry out an ion exchange reaction. The reaction product obtained was filtered and then washed with water. The washed solid phase is finally dried at 100 ° C-110 ° C and then crushed to obtain 243 g of fine powder of NaCuZ [Cu = 6.9
% (Anhydrous basis); Dav = 4.7 μm] was obtained.

It was confirmed that basic salts and oxides of copper (see X-ray diffraction results in FIGS. 2A and 2B) coexist in the NaCuZ powder obtained in this comparative example.

According to the method for producing an antibacterial zeolite according to the present invention, the purity of NaCuZ is higher and the coexistence of impurities such as a copper basic salt and an oxide is prevented, as compared with the case of comparing both Example 2 and Comparative Example 2. There was found. It was also found that the agglomeration phenomenon between particles during the production of NaCuZ was suppressed to a minimum by this method.

Example 3 This example shows an example of producing a NaSnZ type antibacterial zeolite based on the method for producing an antibacterial zeolite of the present invention. A-type zeolite dry powder [1.04 Na ₂ O ・ Al
₂ O ₃ · 1.9 SiO ₂ · xH ₂ O; Dav = 1.5 μm; EC = 7.42 meq / g (anhydrous basis)] 0.24 MSnSO ₄ solution [C ₂ H ₅ OH (25
v / o) -H ₂ O (75 v / o)] about 1.7 and diluted sulfuric acid was added to the resulting mixture to bring the pH of the solution to a final value of 2.3.
Adjusted to. Next, the mixed slurry liquid was kept at around 25 ° C. for 4 hours with stirring. After completion of the above ion exchange, the product was filtered, and then a C ₂ H ₅ OH-containing liquid [C ₂ H ₅ OH (50 v / o) -H
₂ O (50 v / o)]. The washed solid phase is finally dried at 100 ℃ ~ 110 ℃, then crushed to 0.42 kg fine powder of NaSnZ [Sn = 9.6% (anhydrous basis); Dav = 1.7μ
m] was obtained.

The tin content in the NaSnZ powder obtained in this example was 90% or less of the theoretical exchange capacity of NaZ used. In the white NaSnZ obtained in this example, the presence of impurities such as SnO and SnO ₂ was not confirmed.

Comparative Example 3 This example describes the case where NaSnZ type antibacterial zeolite powder was produced by performing ion exchange in an aqueous solution.
To about 0.47 kg of the same dry powder of A-type zeolite as in Example 3, about 1.7 of a 0.25 MSnSO ₄ solution (aqueous solution) was added,
The pH of the obtained mixed solution was finally adjusted to 2.4 with dilute sulfuric acid.
Adjusted to. Next, the mixed slurry liquid was kept at around 25 ° C. under stirring for 4 hours to carry out an ion exchange reaction. The reaction product was filtered, washed with water, dried at 100 ° C to 110 ° C, and then crushed.

In this comparative example, 0.44 kg of fine powder of NaSnZ [Sn = 9.9% (anhydrous basis); Dav = 2.3 μm] was obtained. N obtained in this example
The aSnZ powder had a light yellow color, and the presence of impurities such as SnO and SnO ₂ was confirmed.

The effect of the method for producing an antibacterial zeolite of the present invention is more obvious than the comparison between Example 3 and Comparative Example 3.

Example 4 This example describes an example of producing a composite NaAgZnZ antibacterial zeolite based on the method for producing an antibacterial zeolite of the present invention. Dry powder of A-type synthetic zeolite [1.08Na ₂ O ・
_{Al 2 O 3 · 1.98SiO 2 ·} xH 2 O; Dav = 2.5μm; EC = 7.51meq / g
(Anhydrous basis)] 0.11MAgNO ₃ −0.72MZn (NO
₃ ) ₂ Mixture 2 and a small amount of water were added to the resulting slurry-containing liquid to further add water and ethyl alcohol to keep the total content at about 3.7. The pH of the slurry-containing solution was 3.2 using dilute nitric acid, and the content of ethyl alcohol was 35% (v /
o). The ion exchange reaction was then carried out at 25 ° C. for 4 hours with stirring. The product obtained is filtered and then
It was washed with a C ₂ H ₅ OH-containing solution [C ₂ H ₅ OH (50 v / o) -H ₂ O (50 v / o)]. The washed solid phase is finally dried at 100 ° C-110 ° C and then crushed to obtain 980 g of fine powder of NaAgZnZ [Ag
= 2.8%; Zn = 12.8% (anhydrous standard; Dav = 2.7 μm).

The content of Ag and Zn in the NaAgZnZ powder obtained in this example was 4.2 me.
q / g (anhydrous basis), which corresponds to 90% or less of the theoretical exchange capacity of NaZ used, its purity is high, and precipitation of basic salts or oxides of silver or zinc is not confirmed. It was Third
The figure shows an electron micrograph of the NaAgZnZ dry powder obtained in Example 4, which is a typical A-type zeolite cubic crystal, on the surface of which impurities such as silver and zinc are contained. Almost no precipitation of basic salts or oxides is found. Also, Dav of NaZ used as a starting material is 2.5 μm, while that of the obtained NaAgZnZ powder is 2.7 μm. From this, it was found that the secondary aggregation of NaAgZnZ was almost suppressed by the method of the present invention.

Comparative Example 4 This example describes the case where NaAgZnZ type antibacterial zeolite was produced by carrying out ion exchange in an aqueous solution.
A-type synthetic zeolite dry powder [1.04Na ₂ O ・ Al ₂ O ₃・ 1.9Si
O ₂ · xH ₂ O; Dav = 1.5 μm, EC = 7.42 meq / g (anhydrous standard)] Approx.
0.1MAgNO ₃ -0.71MZn (NO _{3) 2} mixture 2 was added to 1 kg. Additional water was added to the resulting slurry to maintain the total volume at about 3.6 and its pH at 6.7. Ion exchange was carried out by keeping the above slurry liquid at around 25 ° C. under stirring for 4 hours. The transformant obtained was filtered and then washed with water. Antibacterial zeolite after washing with water is 100 ℃ -110 ℃
967g of fine powder of NaAgZnZ after being dried in
[Ag = 2.5%; Zn = 12.3% (anhydrous basis); Dav = 2.2 μm]
was gotten. An electron micrograph of NaAgZnZ obtained in Comparative Example-4 is shown in FIG. Precipitation of impurities such as basic salts and oxides is clearly observed on the surface of the obtained NaAgZnZ cubic crystal.

The superior effect of the method for producing an antibacterial zeolite of the present invention is clearer than the comparison between Example 4 and Comparative Example 4.

Next, the evaluation test of antibacterial activity will be described. The mortality was measured as a means for evaluating the antibacterial activity of the antibacterial zeolite powder obtained in the present invention. Antibacterial (staphylococcus a
ureus) Prefectural suspension (10 ⁴ / ml) 1 ml test substance suspension (100 mg / ml)
The mixture was poured into 9 ml of water and allowed to act at 37 ° C for 48 hours, 0.1 ml of the mixture was dispersed in Mueller Hinton medium, and after 24 hours at 37 ° C, the number of survivors was measured to determine the mortality. On the other hand, fungus (As
pergillus flavus) was measured by the following method. 1m of Aspergillus flavus spore suspension (10 ⁴ / ml)
Inject and pour l into 9 ml of the test substance prefecture suspension (500 mg / ml),
It was allowed to act for 24 hours at 30 ° C. 0.1 ml thereof was dispersed in Sabouraud agar medium, and after 48 hours at 30 ° C., the number of surviving was measured to determine the mortality.

The measurement results are shown in Table 1. The NaAgZ, NaCuZ, NaSnZ and NaAgZnZ antibacterial zeolite powder produced by the method of the present invention exhibits an excellent antibacterial action against bacteria and fungi.

As shown, A-type zeolite powder NaZ (Examples 1 to 4)
The starting materials of and the starting materials of Comparative Examples 1 to 4) do not show antibacterial activity. From the comparison between Example 2 and Comparative Example 2 regarding NaCuZ, the former shows a better antibacterial action than the latter. In the latter case, the original antibacterial activity of NaCuZ is reduced because the copper basic salt or oxide as an impurity component is deposited on the surface of NaCuZ.
A similar phenomenon is found in the NaSnZ powder. The high-purity antibacterial zeolite powder of NaSnZ (Example 3) has higher antibacterial activity than that of the basic salt or oxide of tin deposited on the surface of NaSnZ (Comparative Example 3). Shows the action.

In summary, the present invention provides a method for producing a novel antibacterial zeolite, and fine powders of various antibacterial zeolites obtained by the present invention are considered to be optimal as an antibacterial filler when antibacterializing a polymer. To be

[Brief description of drawings]

1A and 1B are X-ray diffraction patterns of the NaAgZ powder obtained in Comparative Example 1. 2A and 2B are X-ray diffraction patterns of the NaAgZ powder obtained in Comparative Example 2. FIG. 3 is an electron micrograph of the crystal structure of the NaAgZnZ dry powder obtained in Example 4. FIG. 4 is an electron micrograph of the crystal structure of NaAgZnZ dry powder obtained in Comparative Example 4.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area A61K 33/24 A61K 33/24 33/26 33/26 33/30 33/30 33/34 33 / 34 33/38 33/38 C08K 3/34 KAH C08K 3/34 KAH C09D 5/14 PQM C09D 5/14 PQM

Claims (3)

(57) [Claims] 1. One or two selected from the group of antibacterial metals consisting of silver, copper, zinc, tin, lead, bismuth, iron and chromium.
A method for producing an antibacterial zeolite, wherein at least 90% of the theoretical value of the ion exchange capacity of the zeolite is replaced with an antibacterial metal by reacting at least one kind of metal ion with zeolite in an alcohol-water mixture having a pH of 6 or less. 2. A method for producing a fine powder of antibacterial zeolite according to claim 1, by carrying out the method of the preceding paragraph using a zeolite powder having a particle diameter of 10 μm or less. 3. An antibacterial zeolite obtained by substituting 90% or less of the theoretical value of the ion exchange capacity of zeolite with an antibacterial metal by the method of claim 1, filtered and then mixed with an alcohol-water mixture. Alternatively, a method for producing an antibacterial zeolite comprising fine powder having a high dispersibility, which is obtained by washing with alcohol or both liquids and then drying.