JP3490605B2 - Antibacterial zeolite composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an antibacterial zeolite composition. More specifically, the present invention relates to an antibacterial zeolite composition which retains sufficient antibacterial properties when used in a resin and does not cause coloring of the antibacterial resin during molding. Further, the present invention relates to an antibacterial zeolite composition in which the antibacterial resin does not discolor even after being subjected to the influence of heat or light after molding.

[0002]

2. Description of the Related Art With respect to conventional antibacterial zeolites carrying antibacterial metal ions, metal ions such as silver ions, copper ions or zinc ions carried on the zeolite for imparting antibacterial property are not affected by heat or light. Due to the effect, it tends to be released from the zeolite, and it is colored when kneaded into the resin and molded, and the antibacterial resin after molding is discolored significantly due to the influence of heat, light, moisture, etc. over time. Was lost.

As a solution to these drawbacks, an invention has been disclosed in which an antibacterial zeolite is heat-treated at 700 ° C. or higher (JP-A-4-13409). However, probably because the silver ions on the zeolite surface change to silver oxide at the stage of heat treatment, not only the zeolite becomes somewhat blackish, but also due to the zeolite becoming ceramic,
Probably because the silver ions are confined in the pores or changed to metallic silver, the antibacterial property tends to be significantly reduced when used in a resin. Further, an invention has been disclosed in which a surface of an antibacterial zeolite is coated with a silicone coating film (Japanese Patent Publication No. 3-80814). However, the weather resistance of the coating is poor, and the coating tends to deteriorate relatively easily under the influence of heat, light, or moisture, and along with this, liberation of antibacterial metal ions is likely to occur, and also the above-mentioned drawbacks are completely solved. Has not reached. In addition, Ti, Zr, Ce
Alternatively, an invention in which an oxide such as Zn is coated is disclosed (JP-A-6-183728). However,
This oxide not only lacks the filter effect that suppresses the release of antibacterial metal such as silver, which has a poor interaction with the antibacterial zeolite and causes discoloration, and it also has a shortage of TiO ₂ and ZrO.
Due to the difference in the refractive index from the resin as shown in ₂ , it may be impractical because the transparency of the resin may be reduced and the commercial property may be impaired. In addition, as a compounding agent for calcium phosphate-based ceramics, zirconia, alumina, silica, silicic acid, iron oxide,
Inventions using metal oxides such as titanium oxide, calcium oxide, and magnesium oxide have been disclosed (JP-A-6-1708 and JP-A-6-87714). However, this proposal is the content of the invention aiming at the antibacterial property improving effect by increasing the action of active oxygen due to the coexistence of an inorganic oxide, and no detailed example is described for the effect of suppressing resin discoloration. Furthermore, there is no mention of the content that application to a zeolite-based antibacterial agent can suppress resin discoloration. Further, an invention has been disclosed in which the discoloration of an antibacterial polyolefin is suppressed by using an oxide of Group II of the periodic table as a neutralizing agent for the residual chlorine compound-based catalyst contained in the polyolefin ( JP-A-3
No. 153745). However, it is intended to remove the intrinsic discoloration factor only in polyolefin, not to suppress the discoloration factor of the antibacterial agent itself. Therefore, it cannot be applied to general-purpose resins other than polyolefin, and even when it is applied to polyolefin, another devise is required to suppress the discoloration factor due to the antibacterial agent itself.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antibacterial zeolite composition which has sufficient antibacterial performance, can be easily and uniformly dispersed in a resin, and is not colored even when the resin is molded. To do. Another object of the present invention is to provide an antibacterial zeolite composition in which there is almost no color change with time of the resin after molding.

[0005]

In order to solve the above-mentioned problems, the present inventor has found that an antibacterial zeolite contains a phosphoric acid compound,
And an alkaline earth metal oxide, wherein the phosphoric acid compound is mixed with at least 1 of the antibacterial zeolite.
Soaking for more than an hour, and oxidizing the alkaline earth metal
The present inventors have found an antibacterial composition characterized in that the compounding ratio of the product is 0.2 <(alkaline earth metal oxide / antibacterial zeolite) <10 on a weight basis. The present invention will be described in detail below.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Zeolites are generally aluminosilicates having a three-dimensional skeleton structure and generally xM.
_{It is represented by 2 / n} O · Al ₂ O ₃ · ySiO ₂ · zH ₂ O. M represents an ion-exchangeable metal ion, and in addition to sodium ion, potassium ion, calcium ion,
It means a monovalent or divalent metal ion such as magnesium ion or iron ion. For example, most of the synthetic zeolite A-type zeolite is sodium ion and other metal ions are extremely small. n corresponds to this valence. On the other hand, x and y represent the coefficients of metal oxide and silica, and z represents the number of crystal water.

As the zeolite in the present invention, both natural zeolite and synthetic zeolite can be used. Examples of natural zeolites include anarsine, chabazite, clinoptilolite, erionite, faujasite, mordenite and phillipsite. On the other hand, a typical synthetic zeolite is A
Type zeolite, X type zeolite, Y type zeolite, mordenite and the like. In particular, since the synthetic A-type zeolite has a large discoloring effect, the effect of the present invention is remarkable.

The shape of the zeolite is preferably powder particles, and the particle diameter may be appropriately selected depending on the application. When the antibacterial zeolite of the present invention is mixed and used in a thick molded product such as various containers, pipes, granular materials or thick denier fibers, the particle diameter is several microns to several tens of microns or several hundreds of microns. However, when it is formed into a fine denier fiber or film, it is preferably 5 microns or less, and particularly preferably 2 microns or less.

As the antibacterial metal in the present invention, silver,
Examples include copper, zinc, bismuth, cobalt, nickel, or a combination of two or more thereof. Preferably,
Silver, copper, zinc, or a combination of two or more thereof is used, and particularly silver alone or a combination of silver and copper or zinc has excellent antibacterial properties. In the case of silver-supported antibacterial zeolite, it is generally known that resin discoloration under heat or light tends to be particularly large, but in the case of the present invention, discoloration while maintaining antibacterial property Is sufficiently suppressed.

The antibacterial metal ion is preferably carried on the zeolite solid particles by an ion exchange reaction.
This is because the antibacterial effect of the final product may be insufficiently sustained if the metal compound is simply adsorbed or adhered without using the ion exchange method.

As a method for supporting the antibacterial metal ion on the zeolite, the zeolite is immersed in a previously prepared mixed aqueous solution containing the antibacterial metal ion such as silver ion, copper ion or zinc ion, Ion exchange with ionizable ions. The immersion conditions are 10 to 80 ° C., preferably 40 to 60 ° C. for 3 hours or more, and preferably 5 to 10 hours. Further, each metal ion in the mixed aqueous solution is supplied as a salt with a nitrate ion, a sulfate ion, an acetate ion or the like. Examples of silver ions include silver nitrate, silver sulfate, and silver acetate.

While having sufficient antibacterial properties, it can be easily and uniformly dispersed in the resin, does not become colored even when the resin is molded, and there is almost no discoloration of the resin after molding. As such an antibacterial zeolite composition,
The antibacterial composition is preferably 0.1 <alkaline earth metal oxide / antibacterial zeolite <10 by mixing the antibacterial zeolite supporting the antibacterial metal ion with the alkaline earth metal oxide. . The mechanism of action is not clear, but at the melting temperature during resin molding, some of the alkaline earth metal oxides are part of the zeolite due to interaction with the water content of the alkaline earth metal and the water content inside the zeolite. It is presumed that it may be exchanged with the internal sodium ion and supported as an alkaline earth metal ion inside the zeolite to contribute to the suppression of liberation of antibacterial metal ions such as silver which cause coloring and discoloration. Also in the case of alkali metal oxides, a part of them can be supported as alkali metal ions by ion exchange, but in the case of alkali metal ions, hydrolysis of the resin is promoted, which may cause resin coloring or discoloration. Not preferable.

Examples of the alkaline earth metal oxide used in the present invention include beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, and radium oxide, but magnesium oxide and calcium oxide are particularly effective. Is.

The alkaline earth metal oxide may be added to the antibacterial zeolite powder in an amount of 0.1 to 10 times, preferably 0.3 to 5 times the alkali of the antibacterial zeolite powder after drying or heat treatment. After mixing the earth metal oxide powder, it is preferable to make the size of the powder particles uniform while using a mortar, a raker, a ball mill, a powder mixer or the like for homogenous dispersion. If the amount of the alkaline earth metal oxide powder is 0.1 times or less of the antibacterial zeolite powder, the effect of suppressing coloring and discoloration is poor, and if it is 10 times or more, the concentration of the antibacterial agent is diminished. Antibacterial properties become poor when the compounding amount of the above is uniform. Also,
The particle size of the alkaline earth metal oxide powder is preferably submicron to several microns.

The present inventor has also found that when the antibacterial zeolite carries phosphate ions, the compounding effect of the alkaline earth metal oxide is particularly preferable. The mechanism of action is not clear, but due to the electrostatic force between the alkaline earth metal ion and the phosphate ion or the polyphosphate ion generated by the heat treatment of the phosphate ion,
It is speculated that a filter effect may be exhibited that further suppresses the release of antibacterial metal ions such as silver, which causes coloring and discoloration.

The method for supporting the phosphate ions on the zeolite may be either during the ion exchange of the antibacterial metal ions or before or after the ion exchange, but the phosphate ions are supported after the antibacterial metal ions are supported. The method is preferable because phosphate ions are supported on the surface of zeolite, and as a result, desorption of silver ions is suppressed. Next, regarding a method of supporting phosphate ions on zeolite, an example of supporting phosphate ions after supporting antibacterial metal ions will be illustrated below.

Zeolite carrying antibacterial metal ions is dipped in an aqueous solution of phosphoric acid or an aqueous solution of ammonium phosphate which has been prepared to an appropriate concentration in advance, and 1 to 30%, preferably 2 to 10% of phosphate ions are zeolited. Replace and carry the hydroxide ion inside. As the immersion conditions, for example, about 30% of the zeolite carrying an antibacterial metal ion in an aqueous solution is added to an aqueous phosphoric acid solution or an aqueous ammonium phosphate solution at 10 to 70 ° C., preferably 20 to 60 ° C.
It is preferable that the phosphate ions are replaced with the hydroxide ions inside the zeolite by immersing it for at least 1 hour or more, preferably 5 hours or more. Incidentally, with respect to the zeolite carrying the antibacterial metal ions, excess free silver, zinc, for the purpose of washing antibacterial metal ions such as copper, just by contacting with a phosphoric acid aqueous solution or ammonium phosphate aqueous solution for a short time, The present inventor has confirmed that the phosphate ion is not supported inside the zeolite and the desired effect is not exhibited.

The zeolite carrying 1 to 30% of phosphate ions is washed with water and dried, and then the phosphate ions carried inside the zeolite are firmly fixed in the zeolite.
The heat treatment is preferably performed at 00 to 800 ° C. Particularly preferred is the case of heat treatment at 250 to 750 ° C., in which the water of crystallization inherent in the zeolite, which has some influence on the liberation and desorption of silver ions, is minimized (the zeolite structure observed by X-ray diffraction measurement). It is possible that the desorption and liberation phenomena of silver ions can be significantly suppressed, probably because the phosphate ion supported on the zeolite is changed to polyphosphoric acid and the protective film function of the zeolite surface is expressed. Is. 80
Above 0 ° C, the silver-zeolite structure changes,
Not only coloring and agglomeration may occur, but the antibacterial property may be lost.

Even more surprisingly, the present inventor has found that, in addition to antibacterial metal ions and phosphate ions, 2-10% calcium, magnesium, beryllium, strontium,
Alternatively, it has been found that the effect of blending the alkaline earth metal oxide of the present invention is more remarkable when an alkaline earth metal ion such as barium is supported. This is because, when alkaline earth metal ions are supported, the phosphate effect separately supported inside the zeolite or by interaction with polyphosphate ions has a filter effect of further suppressing the release of silver ions. It is considered that the compounding effect of the alkaline earth metal oxide of the invention appears synergistically there.

Next, a phosphate-water mixed solution dipping method for introducing alkaline earth metal ions when introducing phosphate ions will be illustrated. Zeolites carrying approximately 30% of antibacterial metal ions in water are treated with alkaline earth metal monophosphates, diphosphates, or secondary alkaline earth metals such as calcium, magnesium, beryllium, strontium, or barium at predetermined concentrations. Dip in a triphosphate-water mixture (pH adjusted to about 5-7), 10-70 ° C, preferably 20-60 ° C
It is characterized in that the alkaline earth metal ion is supported on the ion exchangeable part of the zeolite by immersing it for at least 3 hours or longer, preferably 6 hours or longer. By carrying this alkaline earth metal ion, not only further advance the substitution with sodium ion remaining on the zeolite surface portion, but also by interaction with the phosphate ion introduced into the zeolite, silver ion in the zeolite It becomes possible to more effectively suppress the release of. At this time, from the viewpoint of water solubility, preferred are primary phosphate, secondary phosphate,
The order of tertiary phosphate is. In the case of the secondary phosphate or the tertiary phosphate, it is preferable to add phosphoric acid separately.

The antibacterial zeolite composition of the present invention has a white pigment such as aluminum oxide, zinc oxide, titanium oxide and silicon dioxide, synthetic hydrotalcite, aluminum tripolyphosphate and aluminum silicate in order to compensate for its whiteness. , Zinc silicate, aluminum borate, ammonium borate, zinc borate, or various ultraviolet absorbers, various metal deactivators, various heat stabilizers and the like can be appropriately contained according to the purpose of use.

The antibacterial zeolite composition of the present invention can be used in the same fields as conventional antibacterial zeolites, and in particular, it can be blended with any low molecular weight or high molecular weight organic polymer to exhibit antibacterial properties, Does not discolor the polymer formulation. It is characterized in that the compound does not discolor even with respect to engineering plastics such as ABS resin and polyester resin having a relatively high melting point, which has been a drawback in the past. As the organic polymer, for example,
Polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyamide, polyester, polyester elastomer, polyvinyl alcohol, polycarbonate, polyacetal, ABS resin,
Thermoplastic synthetic resins such as acrylic resin, vinyl acetate resin, fluororesin, polyurethane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, urethane resin and other thermosetting synthetic polymers,
Regenerated or semi-synthetic polymers such as rayon, cupra, acetate and triacetate are shown. Further, it can be blended with a paper raw material in papermaking or the like. In particular, conventional antibacterial zeolites, especially silver-supported synthetic zeolites, on residual catalysts, polyolefins such as polyethylene and polypropylene having reactive end groups, or engineering plastics such as ABS resins, polyamides and polyesters, which have a particularly high melting point and are molded at high temperature. However, when the antibacterial zeolite of the present invention is used, the discoloration is remarkably suppressed.

Further, the antibacterial zeolite itself obtained by the present invention has a high whiteness, does not discolor during storage, and has a great commercial value. Moreover, since it is well dispersed in the synthetic polymer resin and can be kneaded, it is suitable for use in the fields of food, medicine and hygienic environment, for example, in the form of fibers, films and other molded articles. Also, since the antibacterial zeolite itself is highly safe and stable, it can be applied to a wide range of polymers including paints, adhesives, adhesives, etc.
Now it is possible to improve cleanliness and comfort. It is also possible to use in combination with other antibacterial agents and antifungal agents, particularly organic antibacterial agents and antifungal agents. It is also possible to use it together with other organic insect repellents.

[0024]

EXAMPLES Reference Example 1 (Preparation of antibacterial zeolite) Water was added to 1 kg of A-type zeolite powder having an average particle size of 5 μm and dried at 100 ° C. to make 1.6 l of slurry, and then 0.6 N nitric acid was added. Add aqueous solution and water, PH5-6
Adjusted to. To this slurry, a mixed aqueous solution of salt whose salt concentration was adjusted so that silver nitrate and zinc nitrate were 0.1 M / l and 0.8 M / l, respectively, was added to make a total volume of 4.7 l, and this slurry liquid was stirred at 60 ° C. It was stirred day and night. After ion exchange, the zeolite phase was filtered and washed with water at room temperature until excess metal ions were removed. Then, it was heated and dried at 200 ° C. to prepare an antibacterial zeolite. The contents of silver and zinc in zeolite are 3.4% and 7.5%, respectively.
Met. Reference Example 2 (Preparation of Phosphate Ion-Supporting Antibacterial Zeolite) The antibacterial zeolite powder described in Reference Example 1, phosphoric acid or a phosphoric acid compound, and pure water were mixed and immersed under the predetermined conditions shown in Table 1. Then, it was washed with water and filtered. Then, it was further heat-treated under the conditions shown in Table 1 and then pulverized to obtain a phosphate ion-carrying antibacterial zeolite. Example 1 The antibacterial zeolite of Reference Example 1 and Reference Example 2 and a predetermined alkaline earth metal oxide were blended as shown in Table 2, and then mixed in a mortar to prepare an antibacterial zeolite composition of the present invention. Test Example 1 (Evaluation of coloring during kneading and molding into polycarbonate) Each antibacterial zeolite composition 1 of the present invention obtained in Table 1
280 after mixing with 100 parts by weight of polycarbonate powder (Taflon A2200 manufactured by Idemitsu Petrochemical Co., Ltd.)
Injection molding at IS (Toshiba Machinery IS-EPN type) to obtain a sample plate (size of the sample plate is 50 x
90 × 5 mm), the color tone of which is spectrophotometer CM made by Minolta
Color was measured at -2022, and evaluation was made by polycarbonate containing no antibacterial zeolite and ΔE value. The results are shown in Table 2, and when the antibacterial zeolite composition according to the present invention was kneaded, the ΔE value was 2 or less. Particularly, the antibacterial zeolite according to the present invention was selected from antibacterial zeolite carrying phosphate ions. In each case when the zeolite composition was prepared, Δ
The E value was 1 or less, and in any case, when viewed with the naked eye, almost no difference in color tone from the polycarbonate containing no antibacterial zeolite was observed. On the other hand, when the control 1 containing no alkaline earth metal oxide was kneaded, the ΔE value was as large as 3.5, and it was clearly visible to the naked eye. Also, in the case of Control 2 in which the mixing ratio of the alkaline earth metal oxide was as low as 5%, a slight tendency of coloration was observed. Test Example 2 (Ultraviolet light discoloration test of kneaded polycarbonate) The polycarbonate plate in which each antibacterial zeolite obtained in Test Example 1 was kneaded was placed in an ultraviolet irradiation box (CURELATOR C1 manufactured by Morita Manufacturing Co., Ltd.), and after 24 hours. Take out each color tone and use the Minolta spectrophotometer CM
Color change was measured at -2022, and the degree of discoloration was evaluated by calculating the ΔE value before irradiation. The results are shown in Table 2,
In the case of the sample plate relating to the antibacterial zeolite of the present invention, the ΔE value was within 3 or less, and discoloration with the naked eye was not particularly recognized. Among these, when the antibacterial zeolite composition of the present invention is prepared from the antibacterial zeolite carrying phosphate ions, all have ΔE values of 2 or less, and in addition to the antibacterial metal ion and the phosphate ion, alkaline earth When a metal ion is supported, the ΔE value is 1.
5 or less, and in this case, the heat treatment temperature is 250
It is noteworthy that the ΔE value was 1.0 or less when the temperature was above ° C. On the other hand, in the case of Control 1 in which the alkaline earth metal oxide was not mixed, the ΔE value was as large as 8.0, and it was observed with the naked eye that the yellowish brown color progressed. Test Example 3 (Discoloration test of kneaded polycarbonate in hot water immersion) Each polycarbonate plate prepared in the same manner as in Test Example 1 was immersed in hot water at 60 ° C., taken out from the hot water after 10 days, and dried. The color tone was measured and the degree of discoloration was evaluated by calculating the ΔE value before the immersion in hot water. The results are shown in Table 2.
As described above, the sample plate relating to the antibacterial zeolite of the present invention had a ΔE value of 3 or less, and no discoloration was observed with the naked eye. Among them, in the case of the antibacterial zeolite of the present invention described in Table 2, in each case the ΔE value is 2 or less and further the alkaline earth metal ion is supported in addition to the antibacterial metal ion and the phosphate ion. Had a particularly low ΔE value of 1.5 or less. On the other hand, in the case of Control 1 in which the alkaline earth metal oxide was not mixed, the ΔE value was 12 which was extremely large, and yellowish browning was clearly recognized by the naked eye.
Further, Control 2 in which the mixing ratio of the alkaline earth metal oxide was 0.2 or less was also slightly yellowed. Test Example 4 (antibacterial test of kneaded polycarbonate) As a test strain, Staphylococcus aureus (IFO-1273)
2) was used. The bacterial solution is prepared on an agar medium at 37 ° C for 18
Each test strain that had been cultured for a period of time was suspended in a phosphate buffer (pH 7.2) to prepare a suspension and then diluted to prepare a test bacterial solution. The initial number of Staphylococcus aureus was 5.8 × 10 ⁵ / ml. The antibacterial property was evaluated by dropping the bacterial solution on each polycarbonate plate prepared in the same manner as in Test Example 1, covering the film with a film, and holding the film under conditions of 25 ± 1 ° C. and a humidity of 95% or more for 24 hours. The film was removed and the viable cell count was measured. Each polycarbonate plate prepared in the same manner as in Test Example 2 was used to carry out an antibacterial test on the above-mentioned Escherichia coli and Staphylococcus aureus. The results are shown in Table 3, and the viable cell count was 10 in all the plates related to the antibacterial zeolite of the present invention.
Below, it was determined to be sufficiently antibacterial. On the other hand, it was confirmed that the antibacterial property of Control 3 in which the alkaline earth metal oxide / antibacterial zeolite was 10 or more was slightly poor. Example 3 (Applicability test for resins other than polycarbonate plate) As resins other than polycarbonate, polystyrene (Styron G8509 manufactured by Asahi Kasei), polyamide (6N-D manufactured by Kanebo) and ABS resin (manufactured by Monsanto)
The applicability of the antibacterial zeolite composition NoS-5 of the present invention shown in Table 2 was evaluated from various points by using three kinds of Taflex 410). The injection temperature in each case is
It was carried out at polystyrene: 240 ° C, polyamide: 270 ° C and ABS resin: 260 ° C. The results are shown in Table 4. When the antibacterial Zeoli and the composition of the present invention are mixed with any of polystyrene, polyamide or ABS resin and used, not only there is no resin coloring at the time of molding, It was confirmed that there was almost no resin discoloration thereafter.

[0025]

The antibacterial zeolite composition according to claim 1 of the present invention is colored or colored by the electrostatic force between the alkaline earth metal ion and the phosphate ion or the polyphosphate ion generated by the heat treatment of the phosphate ion. A filter effect that further suppresses the release of antibacterial metal ions such as silver that causes discoloration is exhibited. Further, in the invention according to claim 2 of the present invention, in addition to the above-mentioned effects, when alkaline earth metal ions are supported, phosphate ions or polyphosphate ions separately supported inside the zeolite are added. Has a filter effect of further suppressing the release of silver ions, and the compounding effect of the alkaline earth metal oxide of the invention appears synergistically. As described above, it is possible to provide a high level of antibacterial agent that cannot be considered by the conventional antibacterial zeolite.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI C08K 3/32 C08K 3/32 3/34 3/34 (56) Reference JP-A-8-245326 (JP, A) JP HEI 4-224505 (JP, A) JP-A 1-257124 (JP, A) JP-A 7-138124 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A01N 1 / 00-65/02

Claims (2)

(57) [Claims] 1. An antibacterial zeolite containing a phosphoric acid compound and an alkaline earth metal oxide,
The phosphate compound is added to the antibacterial zeolite for at least 1 hour
An antibacterial composition characterized by being soaked as described above, and the mixing ratio of the alkaline earth metal oxide is 0.2 <(alkaline earth metal oxide / antibacterial zeolite) <10 on a weight basis. 2. The antibacterial composition according to claim 1, which carries an alkaline earth metal oxide .