JPH04231063A - Antimicrobial composition - Google Patents

Abstract

PURPOSE:To obtain a compsn. which comprises of an antimicrobial substance, a polymer, etc., for providing excellent antimicrobial characteristics to various structural body. CONSTITUTION:The title antimicrobial compsn. is prepd. by dispersing in a dispersing medium an antimicrobial substance wherein an antimicrobial metal e.g. silver, copper and/or zinc is adsorbed by using a porous titanium as a supporting body and the surface area of the porous titanium is 100cm<2>/g or larger; when the adsorbed antimicrobial metal is silver single component, the wt. ration of silver component to titanium component (Ag/Ti) is about 0.6X10<-2> or larger; when the adsorbed antimicrobial metals are composite components wherein silver component and copper and/or zinc components are main components, in the region where the amt. of silver component (Ag/Ti) is about 0.6X10<-2> or larger, the amt. of copper component and/or the amt. of zinc component are about 1X10<-2> or larger.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to various structures in which antibacterial properties and a wide range of antibacterial properties are desired, such as building materials such as walls and wallpaper, food packaging materials, industrial goods, various daily necessities, medical equipment, etc. The present invention relates to an antibacterial composition that can be widely applied to base materials, etc. constituting.

0002

BACKGROUND OF THE INVENTION Most methods for imparting antibacterial properties are based on organic antibacterial agents, and organic copper, tin compounds, organic arsenic compounds, organic chlorine compounds, etc. have been widely used. However, the biggest problem was that the more effective these compounds were, the more toxic they became. On the other hand, methods for elution of small amounts of metal ions are also being widely studied. Examples of this include methods for attaching so-called antibacterial metals such as silver and copper in various forms or their oxides to structures, mixing powders into pastes and paints, and blending fibrous materials into fibers. etc. are used. Typical examples of these in the medical field include fixation of silver particles on the surface of catheters (US Pat. No. 4,054,139), and fixation of silver, zinc, cerium, etc. on the surface of medical polymer materials. Metal salt coating method (
U.S. Patent No. 4,612,337, JP-A-62-114
57), or the formation of a metal layer on the surface of the balloon portion of a balloon catheter (Japanese Patent Laid-Open No. 1-135358). However, in either field, they have hardly been put into practical use because they tend to be inferior in the dispersibility of the metal powder, etc. used, and in the degree and sustainability of the resulting effects. In an attempt to improve these drawbacks, attempts have been made to use natural and synthetic zeolites with exchanged metal ions such as silver as antibacterial agents, and to apply them to industrial, daily necessities, and medical supplies (Japanese Patent Publication No. 63-54013, etc.) . Here too, of course, the key to improving antibacterial activity is to make the metal particles fine, but due to restrictions on the particle size of the zeolite itself, the metal particles are not necessarily made into fine particles enough, and the zeolite itself, which has adsorbed silver, etc. It is difficult to obtain a surface coating stock solution or a spray stock solution with good stability, and it is not cheap.

0003

[Problems to be Solved by the Invention] Therefore, the object of the present invention is to provide a composition containing an antibacterial substance that has good dispersibility of antibacterial metals and is low in cost, and which can be applied to various fields. There is.

0004

[Means for Solving the Problems] Titania (titanium oxide) has excellent corrosion resistance and is widely known as a variety of additives. Furthermore, especially titania formed in a gel state is extremely porous, and by adsorbing various metal ions, it can be expected to realize ultrafine metal particles. The present inventors focused on these characteristics and, as a result of intensive study, found that at least one metal selected from silver, which is a typical example of so-called antibacterial metal, copper, zinc metal, etc., was added to porous titania. It was discovered that adsorption shows excellent antibacterial properties.

Various methods can be considered for producing porous titania, but for example, a white gel of titania can be obtained in good yield by adding aqueous ammonia to an aqueous titanium trichloride solution under the action of oxygen. The porous titania is immersed in various desired metal salt aqueous solutions (or mixed solutions) to obtain porous titania that has adsorbed metal ions. In this case, the manufacturing conditions, the pH of the solution, the drying conditions of the gel before ion adsorption, the ion adsorption conditions and adsorption amount, and in the case of multiple ion adsorption, the adsorption ratio of the metal ions, etc.
Furthermore, differences in antibacterial properties can also be seen depending on the firing conditions of these particles. It goes without saying that the same tendency exists even when other methods such as hydrolysis are used. The average grain size of the preferred porous titania according to the present invention is 50 μm.
In order to more uniformly disperse the dispersion medium,
Preferably 10 μm or less, more preferably 5 μm
It is as follows. Silver, which is also known as an antibacterial metal,
Adsorption of copper, zinc or other metals onto porous titania is achieved by immersion in an aqueous solution of a metal salt corresponding to the antibacterial metal. For example, for silver, an aqueous solution of silver nitrate, for copper, an aqueous solution of copper sulfate; for a mixed metal system, silver and copper may be adsorbed in stages, or a corresponding aqueous mixed salt solution may be used.

[0006] Now, the matters related to the antibacterial evaluation carried out in the present invention were as follows. (1) Antibacterial activity of titania gel particles was measured by "minimum inhibitory concentration (MIC)". The measurement of MIC is
Although the method was based on the method established by the Japanese Society of Chemotherapy, since this method generally targets water-soluble antibacterial agents, significant changes had to be made in order to apply it to the insoluble antibacterial agent of the present invention. The main points of the measurement method are as follows. Flasks containing various amounts of antibacterial titania (specimen) are sterilized using high-pressure steam. Add sterilized MH medium to the flask containing the sample and stir.
Add the inoculum solution adjusted to 6/ml. 3 flasks
Regarding the bacterial solution after shaking for 20 hours in a constant temperature shaker at 7℃,
Determine the presence or absence of bacterial growth under a microscope. The minimum negative concentration is taken as the MIC value. (2) The antibacterial activity of antibacterial materials was evaluated in many cases by the so-called shake flask method, in accordance with the "Test method for evaluating the processing effect of sanitary processed products" by the Textile Products Processing Council. A phosphate buffer solution and a specimen are placed in an Erlenmeyer flask, sterilized with high-pressure steam, and then cooled to 37°C. 37 to this
Add the bacterial solution maintained at ℃ and shake at 100 times/min for a predetermined period of time. Measure the number of viable bacteria before and after shaking using the pour-in method. The sterilization rate is the difference in the number of viable bacteria (logarithm) before and after shaking for 3 hours, expressed as a percentage (logarithmic sterilization rate) with respect to the number of viable bacteria (logarithm) before shaking. In the present invention, the logarithmic sterilization rate per unit surface area is used as an index of substantial antibacterial activity so that various specimens with different shapes and specimens with different antibacterial agent concentrations can be handled on the same scale. By the way, a decrease of about 1 x 102 in the number of viable bacteria is
This can be said to be at a practical level showing antibacterial properties.

The amount of antibacterial metal adsorbed onto porous titania depends on the adsorption conditions, but generally depends on the specific surface area (m2/g) of the porous titania. Specific surface area is small, about 100
m2/g or less, the amount of antibacterial metal adsorbed is small;
It is not possible to obtain practical antibacterial activity. Since it is desirable that porous titania has a surface area of 140 m2/g or more for more sufficient antibacterial activity, it is necessary to manage the characteristics of porous titania from this aspect as well. Note that the specific surface area was determined from analysis of nitrogen gas adsorption behavior using the BET method. Now, the antibacterial power of antibacterial titania gel (expressed as MIC value)
roughly depends on the amount of antibacterial metal component adsorbed. Here, the amount of antibacterial metal components is a value determined by plasma emission spectroscopy, and the amount of titanium component (Ti) and silver (or copper, zinc) component (Ag, (or Cu, Zn)) of porous titania.
) is expressed as a weight ratio. Silver in these systems plays an important role, and as specifically described in the examples, in order to obtain effective antibacterial activity when silver component is used alone, the amount of silver component relative to the amount of titanium component must be The weight ratio (Ag/Ti) is
Requires at least about 0.9 x 10-2. More effective antibacterial properties are approximately 3×10-2, and even more advanced effects are approximately 9×
It is 10-2. In addition to the amount of silver component, the effect of the adsorption amount of copper component and/or zinc component is as follows. That is,
In the low silver content region where Ag/Ti is around 3 x 10-2, the effect of the copper content is large, but as the silver content increases, the effect of the copper content gradually fades. Therefore,
Silver components, copper and/or silver components to effectively demonstrate antibacterial power
Alternatively, an example of setting the zinc component composition is as follows. In an example where the silver component amount (Ag/Ti) is about 0.6×10 −2 , the copper component amount (Cu/Ti) is about 1×10 −2 or more, preferably about 2×10 −2 or more. More preferably, the amount of silver component (
Ag/Ti) is approximately 3 x 10-2, and the copper content (Cu/Ti) is approximately 3 x 10-2.
Ti) of about 2 x 10-2 or more, more optimally about 8 x 10
-2 or more. The same result was obtained in an example in which a silver component and a zinc component were selected as antibacterial metals.

The method of imparting antibacterial properties to a base material constituting a structure using the composition using antibacterial titania of the present invention is as follows. To obtain a composition in which porous titania adsorbing a required amount of antibacterial metal is kneaded and dispersed in, for example, a dispersion medium such as a liquid, an oligomer solution, a liquid polymer, a polymer solution, or a polymer melt. I can do it. Further, by coating with these, a particulate or granular antibacterial composition is obtained, and the antibacterial composition is used as a base material of a structure or a member thereof. Of course, it goes without saying that this composition can be directly shaped using it as a molding raw material. Alternatively, water, organic liquid, or inorganic liquid can be used as the dispersion medium. Furthermore, titania powder adsorbed with antibacterial metals,
It is also possible to mix other powders as a dispersion medium and spray the mixture onto the surface of a structure or its base material. Materials for the base material or member of the structure used as the antibacterial composition include polyacrylic, polystyrene, polysulfone, silicone, polyurethane, polyvinyl chloride, various nylons, polyester, polyfluorine, polyethylene, It can be applied to any polymer including polypropylene, polycarbonate, copolymers and blends thereof, cellulose-based polymers, and various materials for binding these. There are no particular restrictions on the use or form of structures to which this method can be applied. The antibacterial titania gel and composition according to the present invention can be used for antibacterial and deodorizing textiles, antibacterial and algae prevention for paints, antibacterial use for pulp, and antibacterial and deodorizing properties for textiles.
Antibacterial of plastics, antibacterial of packaging materials, various adhesive materials,
It can be widely applied for antibacterial purposes such as oil agents.

[0009]

[Action] The mechanism by which so-called antibacterial metals exhibit their strong antibacterial effects has not been fully clarified. It has been known for a long time that small amounts of metal ions have antibacterial effects, but in recent years, the contribution of active oxygen has been discussed here as well, similar to the involvement of active oxygen systems in the disinfection mechanism, which is one of the biological defense mechanisms. It became so. It is thought that this function can be fully exerted by adsorbing metal to this type of gel and forming it into fine particles.

0010

EXAMPLES The present invention will be explained below using examples mainly using silver, copper and zinc as antibacterial metals, but the present invention is not limited to the contents of the examples.

Example 1 Porous titania was put into silver nitrate aqueous solutions of various concentrations, left for one hour, filtered under suction, and the residue was washed with water to obtain antibacterial titania adsorbed with silver. This was subsequently poured into a copper sulfate aqueous solution or a zinc sulfate aqueous solution of a predetermined concentration, left for one hour, filtered under suction, and the residue was washed with water to obtain antibacterial titania that had adsorbed silver components and copper or zinc components. Ta. The copper component amount Cu/Ti (component weight ratio) and the zinc component amount Zn of this sample
/Ti (component weight ratio) and MIC value for Pseudomonas aeruginosa (μg
/ml) is shown in Table 1.

[0011]

[Table 1] The antibacterial titania numbered 4 in Table 1 was mixed with the silicone rubber base in equal weight to create a so-called masterbatch.

Example 2 The masterbatch prepared in Example 1 was kneaded so that the silicone rubber for molding had a predetermined concentration of titania gel to obtain an antibacterial composition. The concentrations of antibacterial titania were 3.2% and 5.1%. A tube was extruded using this rubber according to a normal process. Sterilization rate (%) of this medical tube (sample surface area: adjusted to 10 cm2) against E. coli, Pseudomonas aeruginosa, and Staphylococcus aureus
and antibacterial activity was measured by shake flask method. Table 2 shows the sterilization rate of the logarithm of the number of viable bacteria before and after shaking, and the results obtained by normalizing it by the total surface area of the specimen.

0012

[Table 2]

[Example 3] 1% by weight of the antibacterial titania number 3 in Example 1 was added in small portions with thorough stirring to a commercially available vinyl chloride paint made of vinyl chloride/vinyl acetate copolymer. and uniformly dispersed. The antibacterial paint thus prepared was applied to the surface of the wood block and thoroughly dried. The coated surface was covered with a culture solution containing Escherichia coli and Pseudomonas aeruginosa, cultured under closed conditions, and the presence or absence of bacteria was observed after 8 hours, but no viable bacteria could be found.

[Example 4] Porous titania 0.000.000000000000000, in which silver and copper of "No. 4" in Example 1 were adsorbed onto a polyester chip.
The tow was mixed with 5% by weight and produced into staple yarn by melt spinning, and subjected to stuffing box crimping. The antibacterial activity (logarithmic reduction rate per unit surface area) of this crimped yarn against E. coli using the shake flask method was 3
．． It was 5.

[Example 5] Antibacterial titania "No. 6" in Example 1 was added in an amount of 1% by weight to high-pressure polyethylene, and a packaging film was produced by the inflation method. The antibacterial properties of this film (30 cm2) against E. coli were evaluated by the shake flask method. The number of viable E. coli bacteria before shaking was 2 x 104, but after 3 hours of shaking it was 1 x 1.
It had decreased to 01.

[0013]

[Effects of the Invention] The antibacterial composition according to the present invention has excellent antibacterial properties and is also excellent in processability, such as being applicable to coating techniques, and can easily provide antibacterial structures in a wide range of fields.

Claims (3)

[Claims] Claim 1: An antibacterial composition in which an antibacterial substance obtained by adsorbing an antibacterial metal on a carrier is coated with a dispersion medium or is dispersed in a dispersion medium, wherein the carrier has a specific surface area of 100 m
2/g or more, forming antibacterial titania in which one of the antibacterial metal components adsorbed on the porous titania is at least silver, and the weight ratio of the silver component to the titanium component is 0.2/g or more. An antibacterial composition characterized in that antibacterial titania having a silver content of 9 x 10-2 or more is coated with a dispersion medium or dispersed in a dispersion medium. 2. An antibacterial composition in which an antibacterial substance formed by adsorbing an antibacterial metal on a carrier is coated with a dispersion medium or is dispersed in a dispersion medium, wherein the carrier has a specific surface area of 100 m
2/g or more, the antibacterial metal components adsorbed on the porous titania are mainly silver and copper components and/or zinc components, and the weight ratio of the silver component to the titanium component is approximately 0.6. x10-2 or more, antibacterial titania having a copper content and/or zinc content of about 1x10-2 or more is coated with a dispersion medium or is dispersed in a dispersion medium. Antibacterial composition. [Claim 3] In an antibacterial composition in which an antibacterial substance formed by adsorbing an antibacterial metal on a carrier is coated with a dispersion medium or dispersed in a dispersion medium, the dispersion medium is a polymer and/or an oligomer. The antibacterial composition according to claims 1 and 2, characterized in that: