JP2008209347A - Antimicrobial performance evaluating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easy and convenient antimicrobial performance evaluating method without using microorganisms and live bacteria. <P>SOLUTION: A dissolution speed V of an antibacterial medicine in a step (b) is determined by a formula: (A-A')/T=V and then this antibacterial performance is evaluated with this dissolution speed V as an index, by using an initial quantity A, a remaining quantity A', and a time T, and the following steps of (a), (b), and (c); (a) specifying an initial quantity A of an antibacterial medicine or an element constituting the antibacterial medicine contained in an antibacterial test specimen with antimicrobial process applied; (b) exposing the antibacterial test specimen to an environment that accelerates the dissolution of the antibacterial test specimen for a time T only; (c) specifying a remaining quantity A' of an antibacterial medicine or an element constituting the antibacterial medicine contained in an antibacterial test specimen that has elapsed the step (b). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for evaluating antibacterial performance of a member such as a resin subjected to antibacterial processing.

In recent years, many products with antibacterial treatment are on the market. In the development of antibacterial processed products, a huge number of tests are required to select an antibacterial agent from among a large number of antibacterial agents (organic compound type, organometallic compound type, inorganic compound type, etc.) that have been prototyped. This is because, in a resin product subjected to antibacterial processing, even if the same antibacterial agent is used, there is a difference in antibacterial performance depending on the material of the resin serving as the base material, and the optimum combination of the antibacterial agent and the base material is selected.
As a method for evaluating antibacterial and antifungal properties, an antibacterial test (JIS Z 2801-2000), an antifungal test (JIS Z 2911-2000), or a similar test specified in JIS is generally performed. It is. Non-Patent Document 1 discloses an evaluation method according to the above JIS regulations.

Patent Document 1 discloses that (a) a step of attaching a microorganism whose cell surface is hydrophilic to the surface of a resin sample, and (b) a microorganism attached to the surface of a resin sample, 0.01 to 1 g, a step of culturing in a medium containing 0.13 to 2 g of proteolysate and 0.06 to 1 g of mineral nutrients, and (c) wetting of the resin sample using the growth state of microorganisms on the surface of the resin sample as an index And a method for evaluating antibacterial and antifouling properties in an environment, and a method for evaluating antibacterial and antifouling properties in a wet environment of a resin sample.
Furthermore, in Patent Document 2, a target machine that has been subjected to antibacterial processing and a comparator that is not subjected to antibacterial processing are prepared, applied to respective predetermined surface positions, and air conditioning equipment is operated for a predetermined period of time. The antibacterial performance is evaluated based on the fluctuation of the number of viable bacteria in the comparator, and the number of viable colonies at the start of the evaluation test and the number of viable colonies at the end of the evaluation test are counted. Disclosed is a method for evaluating the antibacterial performance of an air conditioner that counts the number of viable colonies at one or more elapsed times between the end of the evaluation test and grasps the fluctuation tendency of the viable counts in relation to the elapsed time. Has been.

JP 2000-232895 A Japanese Patent No. 3734220 “Guidelines for the management of antibacterial paint products” Japan Paint Manufacturers Association January 2003

All of the above evaluation methods use microorganisms or viable bacteria. Therefore, as a premise for evaluating antibacterial performance, it involves the complexity of preparing and appropriately handling microorganisms or viable bacteria.
The present invention has been made based on such a technical problem, and an object thereof is to provide a method for evaluating antibacterial performance without using microorganisms or viable bacteria.

  For these purposes, the present inventors conducted an environmental exposure test on a resin subjected to antibacterial processing (antibacterial test piece) and measured the rate at which the antibacterial agent eluted from the antibacterial test piece. On the other hand, the antibacterial performance evaluation according to JIS was performed about this antibacterial test piece. As a result, it was found that there is a relationship between the dissolution rate of the antibacterial agent and the antibacterial performance evaluation according to JIS. The present invention is based on this finding, the step (a) of specifying the initial amount A of the antibacterial agent or the element constituting the antibacterial agent contained in the antibacterial test piece subjected to antibacterial processing, and the antibacterial test piece A step (b) of exposing the antibacterial agent to an environment that accelerates the dissolution of the antibacterial agent for a time T, and a step of identifying the antibacterial agent contained in the antibacterial test piece that has undergone the step (b) or the remaining amount A ′ of the element constituting the antibacterial agent Using (c), the initial amount A, the remaining amount A ′ and the time T, the elution rate V of the antibacterial agent in step (b) is obtained from the formula: (AA ′) / T = V, and this elution rate V It is an antibacterial performance evaluation method characterized by evaluating antibacterial performance using as a parameter.

  As described above, according to the present invention, the antibacterial test piece is exposed to an environment for accelerating the elution of the antibacterial agent for a predetermined time, and the antibacterial performance is evaluated by determining the elution rate of the antibacterial agent during that time. is there. Therefore, the present invention can provide a simple method for evaluating antibacterial performance without using microorganisms or viable bacteria as in the prior art.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a flowchart showing a procedure of an antibacterial performance evaluation method according to the present embodiment.
As shown in FIG. 1, the antibacterial performance evaluation method is performed according to the following procedures: antibacterial test piece preparation, environmental exposure test, antibacterial agent residual amount analysis, dissolution rate calculation, and antibacterial performance evaluation. Hereinafter, each procedure will be described.

<Preparation of antibacterial test piece>
The antibacterial test piece is subjected to antibacterial processing.
As the base material of the antibacterial test piece, materials that have been subjected to antibacterial processing, such as resin, fiber, metal, ceramics, paint, rubber, wood, and paper, can be widely used.
On the other hand, as the antibacterial agent, inorganic antibacterial agents such as silver and copper having high binding properties to proteins can be used. Alcohol, phenol, aldehyde, carboxylic acid, ester, ether, nitrile, peroxide / epoxy, halogen, pyridine / quinoline, triazine, isothiazolone, imidazole, thiazole Organic antibacterial agents such as anilide, biguanide, disulfide, thiocarbamate, peptide protein, surfactant and organometallic can also be used. Furthermore, an organic-inorganic hybrid antibacterial agent can also be used.

  The specific method of the antibacterial processing is appropriately selected depending on the base material and the antibacterial agent to be used, and there are mainly a method of coating the surface of the base material and a method of dispersing in the base material. The method for coating the surface of the substrate is not limited to the substrate to be used. The coating method may be selected depending on the antibacterial agent used. On the other hand, the base material to which the method of dispersing in the base material is applied is limited. Typically, when a resin is used as a base material, an antibacterial test piece in which the antibacterial agent is dispersed can be obtained by preparing a resin raw material in which the antibacterial agent is blended and injection molding the resin raw material. In this case, in order to improve the dispersibility of the antibacterial agent, it is realistic to blend a master batch containing the antibacterial agent into the resin raw material. Similarly, an antibacterial test piece in which an antibacterial agent is dispersed is also effective when rubber is used as a base material.

  At the stage of preparing the antibacterial test piece, the amount of the antibacterial agent contained (initial amount A) is specified. The initial amount A of the antibacterial agent is usually the amount of the antibacterial agent added during the preparation of the antibacterial test piece. However, when the antibacterial agent decreases during the preparation of the antibacterial test piece, It is necessary to specify the amount of the agent. Moreover, the quantity of the specific element contained in an antibacterial agent can also be specified. In addition, even when the antibacterial agent is processed on the surface of the base material by coating, it is regarded as being contained in the antibacterial test piece in the present invention.

<Environmental exposure test>
The antibacterial test piece obtained as described above is subjected to an environmental exposure test.
Antibacterial agents usually elute from the substrate over time. Environmental exposure tests are conducted to accelerate the rate at which antimicrobial agents dissolve. This is to speed up antibacterial performance evaluation.
Specifically, the environmental exposure test is realized by exposing the antibacterial test piece to a heating environment, a corrosive environment, a wet environment, or the like. It is desirable that the specific environment is adapted to the application and product to be applied by evaluating antibacterial performance. For example, when antibacterial performance is evaluated for a product used in a high temperature environment, the antibacterial test piece may be exposed to a heated environment.
The environmental exposure test is performed by setting a predetermined time (T) in order to determine the elution rate of the antibacterial agent that is required later.

<Antibiotics remaining amount analysis>
When the environmental exposure test for a predetermined time T is completed, the remaining amount of the antibacterial agent remaining on the antibacterial test piece is analyzed and measured. As described above, not only the amount of the remaining antibacterial agent itself but also the elements constituting the antibacterial agent may be measured.
Various known analysis methods can be used for the remaining amount of the antibacterial agent. For the organic antibacterial agent, a Fourier transform infrared spectrometer (FT-IR) can be used. An organic compound has a vibration spectrum unique to the substance in the infrared region. Therefore, qualitative analysis can be performed by measuring the infrared absorption wavelength. And quantitative analysis can be performed by measuring the intensity of absorption. The Fourier transform infrared spectrometer is an apparatus that measures an interference curve (interferogram) using an interferometer, and obtains an infrared spectrum by Fourier transforming the interference curve.

  Moreover, when analyzing a specific element, atomic absorption analysis, fluorescent X-ray analysis, an electron beam microanalyzer, etc. can be used. In the case of elemental analysis, it is desirable to select an element with the highest detection sensitivity among the elements constituting the antibacterial agent. This is to obtain the accuracy of identifying the remaining amount of the antibacterial agent. For example, in the case of a pyridine-based organic antibacterial agent shown in the examples described later, it is preferable to use Zn (zinc) as an analysis target. Further, a plurality of elements to be analyzed may be used.

<Elution rate calculation>
If the remaining amount of the antibacterial agent can be specified, then the dissolution rate of the antibacterial agent is calculated.
As shown in FIG. 2, when the initial amount of the antibacterial agent before the environmental exposure test is A and the remaining amount of the antibacterial agent after the environmental exposure test is A ′, the dissolution rate V of the antibacterial agent in the environmental exposure test is V = It is obtained by (AA ′) / T.
As described above, the initial amount A and the remaining amount A ′ can be the amount of the antibacterial agent itself, or can be the amount of a specific element constituting the antibacterial agent. When using an organic antibacterial agent, the above-described Fourier transform infrared spectrometer (FT-IR) may be used to measure the amount of the antibacterial agent itself. Even when an organic antibacterial agent is used, when analyzing specific elements constituting the antibacterial agent, such as N (nitrogen), S (sulfur), and other elements, atomic absorption analysis, fluorescence X-ray analysis, electron beam microanalyzer, or the like may be used.

<Antimicrobial performance evaluation>
The antibacterial performance is evaluated based on the dissolution rate V of the antibacterial agent determined as described above.
The antibacterial performance evaluation is basically performed based on whether the elution rate V is large or small, but there are cases where the antibacterial performance cannot be simply evaluated based on the large or small elution rate V. That is, the high dissolution rate V of the antibacterial agent suggests that the antibacterial effect is immediate. However, since the elution rate V is large, the decrease in the antibacterial agent in the base material is accelerated, and the durability of the antibacterial effect may be inferior.
For example, as shown in FIG. 3, when the evaluation test was performed on the base material A, the base material B, and the base material C with respect to the same antibacterial agent, it was assumed that the elution process of the antibacterial agent was different. . Here, the base material A has the fastest elution rate V, the base material C has the slowest elution rate V, and the base material B is in the middle. In this case, when the base material A is used, an immediate effect is recognized in the antibacterial effect, but the sustainability of the effect is inferior. On the other hand, when the base material C is used, the antibacterial effect has a delayed effect, but it can be said that the effect can be sustained over a long period of time. When the base material B is used, the antibacterial effect is immediately effective and the effect is sustained. Therefore, when the immediate effect of the antibacterial effect is required, the substrate A is selected. Further, when the durability of the antibacterial effect is required, the substrate C is selected. Furthermore, the base material B is selected if both the immediate effect and the sustainability of the antibacterial effect are obtained. The evaluation of antibacterial performance in the present invention includes the above aspects.

  By the way, as shown also in FIG. 3, even if it is the same antibacterial agent, there may be a difference in antibacterial performance depending on the base material. Therefore, the present invention can be applied to find a combination having the highest antibacterial effect among a plurality of types of antibacterial agents and a plurality of types of base materials. As shown also in the Example mentioned later, the dissolution rate V of an antibacterial agent and the result of the antibacterial test prescribed | regulated to JIS respond | correspond. Therefore, a combination of an antibacterial agent having excellent antibacterial effect and a base material is extracted by the method for evaluating antibacterial performance of the present invention without using microorganisms or viable bacteria. This combination is not limited to one, and a plurality of combinations can be extracted. That is, as an evaluation result of antibacterial performance, it may be necessary to finally perform a test according to JIS regulations. Therefore, according to the present invention, a plurality of combinations of antibacterial agents having excellent antibacterial effects and base materials are extracted, and finally, the most preferable combination of antibacterial agents and base materials is selected by performing a test according to JIS regulations. can do.

Antibacterial test pieces were prepared by adding a pyridine-based organic antibacterial agent to polypropylene resin (PP) and polyacrylonitrile butadiene styrene copolymer resin (ABS). An antibacterial test piece was prepared by injection molding with a predetermined amount of an organic antibacterial agent (masterbatch) added to each resin raw material. The dimension of the antibacterial test piece is 50 × 50 × 2 mm. The antibacterial test piece (PP) is an antibacterial test piece (PP) whose base material is a polypropylene resin, and the antibacterial test piece (ABS) is an antibacterial test piece whose base material is a polyacrylonitrile butadiene styrene copolymer resin.
The amount of Zn contained in the antibacterial test piece (PP) and the antibacterial test piece (ABS) was measured. The pyridine-based organic antibacterial agent contains Zn as a constituent element. Therefore, if the fluctuation | variation of Zn content can be grasped | ascertained, the fluctuation | variation of content of a pyridine type organic antibacterial agent can be specified. The Zn content (initial) of the antibacterial test piece (PP) and the antibacterial test piece (ABS) is as follows. The Zn content was measured by EPMA.
Antibacterial test piece (PP): Zn content = 0.518 wt%
Antibacterial test piece (ABS): Zn content = 0.271 wt%

Next, an environmental exposure test was performed in which two types of antibacterial test pieces were exposed to running water for 168 hours. In addition, the antibacterial test piece was arrange | positioned in the water tank, and flowing water was formed by circulating the water in a water tank using a pump. Antibacterial test pieces that have been exposed to running water accelerate the dissolution of the antibacterial agent.
After the test was completed, the Zn content (after running water deterioration) of each antibacterial test piece was measured in the same manner as described above. The results are as follows.
Antibacterial test piece (PP): Zn content = 0.260 wt%
Antibacterial test piece (ABS): Zn content = 0.238 wt%

The dissolution rate of the antibacterial agent was determined from the above variation in Zn content. The results are shown in Table 1.
As shown in Table 1, even when the same pyridine-based organic antibacterial agent is used, the dissolution rate of the antibacterial agent is different if the substrate is different. That is, in the case of a pyridine-based organic antibacterial agent, the elution rate of the antibacterial agent is significantly higher when the polypropylene resin (PP) is used as the base material than when the polyacrylonitrile butadiene styrene copolymer resin (ABS) is used as the base material. fast.

The antibacterial effect was evaluated according to JIS Z 2801-2000 using the above two types of antibacterial test pieces. The evaluation method is as follows.
Antibacterial test piece (PP) and antibacterial test piece (ABS), as well as unprocessed test piece (PP ') and no A processed test piece (ABS ') was prepared. As the antibacterial agent, the aforementioned pyridine-based organic antibacterial agent was used, and the addition amount was two types of 0.1 wt% and 0.5 wt%. The amount added is the amount of the pyridine organic antibacterial agent itself.
Each of the above test pieces was placed on a separate petri dish, and 0.4 ml of liquid bacteria adjusted to 2.5 to 10 × 10 ⁵ cells / ml was dropped onto each test piece. A 40 mm × 40 mm film was placed thereon and brought into close contact with the test piece. In addition, Staphylococcus aureus and Pseudomonas aeruginos were used as bacteria for antibacterial performance evaluation.
Each test piece covered with the film was left in an environment of 35 ° C. and a humidity of 90% or more for 24 hours. Thereafter, the film was peeled off, and the liquid bacteria adhering to the test piece were washed out with a liquid medium, mixed with an agar medium, and cultured at a temperature of 35 ° C. for 48 hours.

Thereafter, the number of viable colonies generated on the medium was counted, the common logarithm of each viable colony number was obtained, and the antibacterial activity value R was obtained by the following formula. In addition, if this antibacterial activity value is 2.0 or more, it is judged that there exists an antibacterial effect.
R = [Log (BA) -Log (CA)] = [Log (B / C)]
A: Average number of viable bacteria before environmental exposure test in unprocessed specimens
B: Average number of viable cells after 24 hours in unprocessed test piece
C: Average number of viable bacteria after 24 hours in antibacterial test piece

  The antibacterial performance evaluation was performed before the flowing water test described above, after 100 hours of flowing water test and after 168 hours of flowing water test. The results of antibacterial performance evaluation are shown in FIGS. 4 to 6 show the results obtained from the antibacterial test piece (PP) and the unprocessed test piece (PP ′), FIG. 4 shows the relationship between the concentration of the antibacterial agent and the antibacterial activity value, and FIG. The relationship between the running time and antibacterial activity value for S. aureus is shown, and FIG. 6 shows the relationship between the running time and antibacterial activity value for Pseudomonas aeruginosa. 7 to 9 show the results obtained by the antibacterial test piece (ABS) and the unprocessed test piece (ABS ′), FIG. 7 shows the relationship between the concentration of the antibacterial agent and the antibacterial activity value, and FIG. FIG. 9 shows the relationship between the running time and the antibacterial activity value for Pseudomonas aeruginosa.

4-9, even if the same antibacterial agent is used, it can be seen that there is a difference in the antibacterial activity value if the substrate is different. When FIG. 4 is compared with FIG. 7, when using a pyridine type organic antibacterial agent, the direction using a polypropylene resin (PP) as a base material is more than using a polyacrylonitrile butadiene styrene copolymer resin (ABS) as a base material. Even antibacterial performance is high. This tendency is the same even when a running water test is conducted. The results are shown in Table 1 (◯, ×).
Therefore, when compared with the antibacterial agent elution rate shown in Table 1, the antibacterial test piece (PP) based on polypropylene resin (PP) having a high antibacterial elution rate is excellent in antibacterial performance. On the other hand, an antibacterial test piece (ABS) based on polyacrylonitrile butadiene styrene copolymer resin (ABS), which has a slow antibacterial elution rate, is inferior in antibacterial performance. From the above results, it can be seen that the antibacterial performance can be generally evaluated by the dissolution rate of the antibacterial agent.

It is a flowchart which shows the procedure of the evaluation method of the antibacterial performance which concerns on this invention. It is a figure explaining the method of calculating | requiring the elution rate V of an antibacterial agent. It is a graph which shows that even if it is the same antibacterial agent, there exists a difference in antibacterial performance by a base material. It is a graph which shows the result of the antibacterial performance evaluation by the antibacterial test piece which makes a base material polypropylene resin (PP). It is a graph which shows the result of antibacterial performance evaluation using Staphylococcus aureus in the antibacterial test piece which makes a base material polypropylene resin (PP). It is a graph which shows the result of antibacterial performance evaluation using Pseudomonas aeruginosa in the antibacterial test piece which makes a base material polypropylene resin (PP). It is a graph which shows the result of the antibacterial performance evaluation by the antibacterial test piece which uses a base material as a polyacrylonitrile butadiene styrene copolymer resin (ABS). It is a graph which shows the result of the antibacterial performance evaluation using Staphylococcus aureus in the antibacterial test piece which makes a base material polyacrylonitrile butadiene styrene copolymer resin (ABS). It is a graph which shows the result of antibacterial performance evaluation using Pseudomonas aeruginosa in the antibacterial test piece which makes a base material polyacrylonitrile butadiene styrene copolymer resin (ABS).

Claims (3)

A step (a) of identifying an antibacterial agent contained in an antibacterial test piece subjected to antibacterial processing or an initial amount A of an element constituting the antibacterial agent;
Exposing the antibacterial test strip to an environment that accelerates the dissolution of the antibacterial agent for a period of time (b);
The step (c) of identifying the antibacterial agent contained in the antibacterial test piece that has undergone the step (b) or the remaining amount A ′ of the element constituting the antibacterial agent;
Using the initial amount A, the remaining amount A ′ and the time T, the elution rate V of the antibacterial agent in the step (b) is obtained by the formula: (AA ′) / T = V, and this elution rate V An antibacterial performance evaluation method characterized by evaluating antibacterial performance using as a parameter.   The antibacterial performance evaluation method according to claim 1, wherein the antibacterial test piece is a resin material in which the antibacterial agent is dispersed.   The antibacterial performance evaluation method according to claim 1, wherein the antibacterial agent is an organic antibacterial agent.

Images