OXIDANT COMPOSITION FOR SUPPRESSING LOSS OF ADHESIVE DURABILITY, AND USE OF SAME

Abstract

The disclosure relates to a microbicidal composition with excellent action of limiting a decrease in durability of synthetic adhesives as well as high microbicidal action. The microbicidal composition contains 0.03 to less than 1.0 mass % of peracetic acid, 0.045 to less than 1.5 mass % of hydrogen peroxide, and 0.036 mass % or more of glycine.

Claims

1. A microbicidal composition comprising peracetic acid, hydrogen peroxide, and glycine, wherein the amount of the peracetic acid is 0.03 to less than 1.0 mass %, the amount of the hydrogen peroxide is 0.045 to less than 1.5 mass %, and the amount of the glycine is 0.036 mass % or more.

2. The microbicidal composition according to claim 1, which is in the form of an aqueous solution with a pH of 2 or greater.

3. The microbicidal composition according to claim 1, further comprising at least one auxiliary component selected from the group consisting of hydrogen phosphate, a chelating agent, and a pH buffer.

4. The microbicidal composition according to any one of claim 1, which is a disinfectant and/or a microbicidal agent for a test object containing an adhesive, wherein the test object is an instrument or equipment for use in the medical or food field requiring disinfection or microbicidal treatment.

5. A combination formulation comprising (A) a formulation containing peracetic acid and hydrogen peroxide, and (B) a formulation containing glycine, wherein the formulation (A) and the formulation (B) are mixed with an aqueous solvent to prepare an aqueous solution before use, the aqueous solution containing 0.03 to less than 1.0 mass % of the peracetic acid, 0.045 to less than 1.5 mass % of the hydrogen peroxide, and 0.036 mass % or more of the glycine, the aqueous solution having a pH of 2 or greater.

6. The combination formulation according to claim 5, wherein the formulation (B) further contains at least one auxiliary component selected from the group consisting of hydrogen phosphate, a chelating agent, and a pH buffer.

7. A method for preparing the microbicidal composition of claim 2, comprising mixing (A) a formulation containing peracetic acid and hydrogen peroxide and (B) a formulation containing glycine with an aqueous solvent to prepare an aqueous solution that contains 0.03 to less than 1.0 mass % of the peracetic acid, 0.045 to less than 1.5 mass % of the hydrogen peroxide, and 0.036 mass % or more of the glycine, and that has a pH of 2 or greater.

8. The method according to claim 7, wherein the formulation (B) further contains at least one auxiliary component selected from the group consisting of hydrogen phosphate, a chelating agent, and a pH buffer.

9. A disinfection equipment comprising a disinfection chamber, and a disinfectant delivery system, wherein the disinfectant delivery system is configured to separately supply (A) a formulation containing peracetic acid and hydrogen peroxide and (B) a formulation containing glycine to the disinfection chamber in which the supplied formulation (A) and the supplied formulation (B) are mixed with a separately supplied aqueous solvent to prepare an aqueous solution that contains 0.03 to less than 1.0 mass % of the peracetic acid, 0.045 to less than 1.5 mass % of the hydrogen peroxide, and 0.036 mass % or more of the glycine, and that has a pH of 2 or greater.

10. The disinfection equipment according to claim 9, wherein the formulation (B) further contains at least one auxiliary component selected from the group consisting of hydrogen phosphate, a chelating agent, and a pH buffer.

11. The disinfection equipment according to claim 9, which is for use in disinfection or microbicidal treatment of a test object containing an adhesive, wherein the test object is an instrument or equipment for use in the medical or food field requiring disinfection or microbicidal treatment.

12. A method for disinfecting a test object, comprising treating the test object with the microbicidal composition of claim 1.

13. The method according to claim 12, comprising, before the treating the test object, mixing (A) a formulation containing peracetic acid and hydrogen peroxide and (B) a formulation containing glycine with an aqueous solvent to prepare the microbicidal composition of any one of claims 1 to 4.

14. The method according to claim 12, wherein the test object contains an adhesive.

15. The method according to claim 14, which is a method for disinfecting the test object while limiting a decrease in durability of the adhesive.

Description

EXAMPLES

[0077] The following describes the present invention with reference to experimental examples to facilitate understanding of the elements and effects of the invention. However, the invention is not limited in any way by these experimental examples. The following experiments were conducted at room temperature (25±5° C.) under atmospheric pressure, unless otherwise noted. Unless otherwise specified, the unit “%” below indicates mass %, and the unit “parts” indicate parts by mass.

Experimental Example 1: Evaluation of Microbicidal Effect

[0078] The microbicidal effect of the microbicidal composition according to the present invention was evaluated by using Aspergillus brasiliensis (ATCC 16404) as a microorganism. A. brasiliensis is an environmental airborne microbe that may pose a risk of contamination in the medical field and forms highly drug-resistant spores in filamentous fungi.

(1) Preparation of Test Composition

[0079] The components shown in Table 2 were dissolved in synthetic hard water to give the individual concentration and pH specified in Table 2, thereby preparing test compositions (Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-7). The synthetic hard water for use was prepared by mixing 6 mL of the following solution A and 8 mL of the following solution B, and adjusting the mixture with distilled water to give a total amount of 1000 mL (the same applies to the Experimental Examples described below).

Solution A: MgCl.sub.2 (1.984 g)+CaCl.sub.2 (4.624 g) were dissolved in distilled water and adjusted to give a volume of 100 mL.
Solution B: MgHCO.sub.3 (3.502 g) was dissolved in distilled water and adjusted to give a volume of 100 mL.

(2) Preparation of Inoculum Solution

[0080] A glycerol stock of A. brasiliensis was inoculated in a malt extract agar medium (Malt Extract Agar: Oxoid Limited) and cultured at 30° C. for 7 days. After culture, 0.05 mass % aqueous polysorbate 80 solution was added, and spores were scraped off with a cell spreader. The obtained spore liquid was placed in a 50-mL centrifuge tube, and 5 g of sterile glass beads was added, followed by stirring for 1 minute. After stirring, the liquid was filtered through a cell strainer (mesh size: 40 μm) twice for use.

(3) Evaluation Test for Microbicidal Effect

[0081] The microbicidal effect of the test compositions (Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-7) was evaluated in accordance with a test method (suspension test) prescribed in EN 13624:2013 (clean conditions). A test composition determined to have a microbicidal effect in this test method is usable in disinfection of a semi-critical instrument or equipment in the medical field as a high-level disinfectant according to the Spaulding's classification. Specifically, a test composition determined to have a microbicidal effect in this test method is determined to have a killing action on yeast-like fungi (including Candida) and filamentous fungi.

[0082] Specifically, the following operations were performed to evaluate the microbicidal effect.

(i) 0.5 mL of an inoculum solution kept at 35° C. beforehand, and 0.5 mL of an aqueous solution of an interfering substance under clean conditions (0.3% BSA (bovine serum albumin), the same below) are placed in a test tube, stirred, and allowed to stand at 35° C. for 2 minutes.
(ii) 4 mL of a test composition (test sample) kept at 35° C. beforehand is placed in the test tube of item (i), mixed, and allowed to act at 35° C.
(iii) After the duration of action indicated in Table 2, 0.5 mL of the mixture solution is taken and placed in 4.5 mL of a neutralizer (0.1% sodium thiosulfate, catalase), and inactivated.
(iv) 0.5 mL of the inactivated mixture solution is applied to the surface of a solid malt extract agar medium and cultured at 30° C.
(v) After three days from the culture, the viable fungi count is measured.
(vi) In accordance with the requirements of EN 13624:2013, a log reduction value of fungi counts before and after the test being 4 Log.sub.10 or higher is determined to be “A: having an effective microbicidal effect,” and otherwise determined to be “B: having no effective microbicidal effect.”

TABLE-US-00002 TABLE 2 Concentration (mass %) in Test Composition (Aqueous Solution) Example Comparative Example Component 1-1 1-2 1-3 1-4 1-1 1-2 1-3 1-4 1-5 1-6 1-7 Peracetic Acid 0.03 0.03 0.04 0.07 0.03 0.015 0.03 0.01 0.02 0.07 0.07 Hydrogen 0.045 0.045 0.06 0.105 0.045 0.045 0.02 0.015 0.03 0.105 0.105 Peroxide Glycine 0.036 0.036 0.048 0.084 0 0.036 0.036 0.012 0.024 0 0 Hydrogen 0 0.009 0.012 0.021 0 0 0 0.003 0.006 0 0.021 Phosphate*.sup.1 Chelating 0 0.0045 0.006 0.0105 0 0 0 0.0015 0.003 0 0.0105 Agent*.sup.2 Stabilizer*.sup.3 0 0.03 0.04 0 0 0 0 0.01 0.02 0 0 pH Adjuster*.sup.4 Moderate Moderate Moderate Moderate Moderate Moderate Moderate Moderate Moderate Moderate Moderate Amount Amount Amount Amount Amount Amount Amount Amount Amount Amount Amount Total with 100 100 100 100 100 100 100 100 100 100 100 Synthetic Hard Water pH 6 6 6 6 6 6 6 7 7 6 6 Micro- Action — — — A — — — — — B B bicidal Time: Effect 5 Min- utes Action B A A — B B B — B — — Time: 20 Min- utes Action A — — — B B B B B — — Time: 30 Min- utes *.sup.1Dipotassium Hydrogen Phosphate *.sup.2Tetrasodium Hydroxyethane Diphosphonate *.sup.3Dipropylene Glycol *.sup.4Potassium Hydroxide or Citric Acid In the table, “—” indicates that no evaluation was made.

[0083] As shown in Table 2, even an aqueous solution containing peracetic acid and hydrogen peroxide (microbicidal components) did not exhibit a desired microbicidal effect when the peracetic acid concentration was 0.03% or less, and the hydrogen peroxide concentration was 0.045% or less, with no glycine contained (Comparative Example 1-1). In contrast, an aqueous solution with a peracetic acid concentration of 0.03%, and a hydrogen peroxide concentration of 0.045%, containing 0.036 mass % or more of glycine, exhibited a desired microbicidal effect (Example 1-1). An aqueous solution with a hydrogen peroxide concentration of 0.045% or more and a glycine concentration of 0.036 mass % or more did not exhibit a desired microbicidal effect when the peracetic acid concentration was less than 0.03% (Comparative Example 1-2), and an aqueous solution with a peracetic acid concentration of 0.03% or more and a glycine concentration of 0.036 mass % or more did not exhibit a desired microbicidal effect when the hydrogen peroxide concentration was less than 0.045% (Comparative Example 1-3).

[0084] These results indicate that a microbicidal composition containing a relatively low concentration of peracetic acid and hydrogen peroxide can exhibit an enhanced microbicidal effect by containing glycine, and that the lowest concentration of each component to exhibit the desired microbicidal effect is the following: 0.03% for peracetic acid, 0.045% for hydrogen peroxide, and 0.036% for glycine. These results also indicate that the microbicidal effect of a microbicidal composition containing predetermined concentrations of peracetic acid, hydrogen peroxide, and glycine can be enhanced by adding an auxiliary component such as hydrogen phosphate, a chelating agent, and a stabilizer (Examples 1-2 and 1-3, and Comparative Examples 1-4 and 1-5). These results also indicate that the microbicidal effect of the microbicidal composition can be enhanced by increasing the amount of peracetic acid, hydrogen peroxide, or glycine (Example 1-4). However, an aqueous solution containing no glycine did not exhibit a desired microbicidal effect even when the amount of peracetic acid and hydrogen peroxide was increased, or when other auxiliary components were added (Comparative Examples 1-6 and 1-7).

[0085] To confirm that the achieved effect is unique to the use of glycine, the same test was performed using, instead of glycine, an equal molar amount of a buffer (acetic acid, trisodium phosphate, or dipotassium hydrogen phosphate) with a pKa ranging from 4.5 to 11.5 disclosed in cited Reference 4 in the formula of Example 1-1. Table 3 shows the results together with the results of Example 1-1 and Comparative Example 1-1.

TABLE-US-00003 TABLE 3 Com- parative Ex- Example ample Experimental Results Component 1-1 1-1 1 2 3 Peracetic Acid 0.03 0.03 0.03 0.03 0.03 Hydrogen Peroxide 0.045 0.045 0.045 0.045 0.045 Glycine 0.0 0.036 0 0 0 Acetic Acid 0.0 0.0 0.03 0.0 0.0 Trisodium 0.0 0.0 0.0 0.08 0.0 Phosphate Dipotassium 0.0 0.0 0.0 0.0 0.08 Hydrogen Phosphate pH Adjuster*.sup.1 Mod- Mod- Mod- Mod- Mod- erate erate erate erate erate Amount Amount Amount Amount Amount pH of Sterilizing 6 6 6 6 6 Composition Micro- Action — — — — — bicidal Time: Effect 5 Min- utes Action B B B B B Time: 20 Min- utes Action B A B B B Time: 30 Min- utes *.sup.1Potassium Hydroxide or Citric Acid Note: “—” indicates that no evaluation was made. Note: A log reduction value of 4 Log or higher is “A,” a log reduction value of less than 4 Log is “B.”

[0086] As is clear from the results, unlike glycine, acetic acid, trisodium phosphate, and dipotassium hydrogen phosphate could not enhance the microbicidal activity of the acidic oxidant of peracetic acid and hydrogen peroxide.

Experimental Example 2: Evaluation of Effect of Limiting Decrease in Durability of Synthetic Adhesive

[0087] The effect of limiting a decrease in durability of adhesives by a microbicidal composition (corrosion inhibitory effect) was evaluated by using a silicone adhesive, an epoxy resin adhesive, and a vinyl acetate resin adhesive as synthetic adhesives.

(1) Preparation of Microbicidal Composition

[0088] The components listed in Tables 4 to 9 were dissolved in distilled water to give the concentration and pH indicated in these tables, thereby preparing microbicidal compositions.

(2) Preparation of Adhesive Test Piece

[0089] Vinyl tape (3 cm×5 cm) with two punched holes (14 mm in diameter, 2×1 row) was adhered to one surface of a test piece (3 cm×5 cm, thickness: 1.0 mm) made from SUS304 (austenite stainless steel), and an adhesive was poured into the holes. The surface was evenly spread with a spatula to match the height of the adhesive with the height of the vinyl tape, and the test piece was allowed to stand at room temperature for 24 hours or longer. After drying, the vinyl tape was peeled off, thereby preparing an adhesive test piece with the adhesive adhered on two spots on one surface.

[0090] For the adhesive, three types of adhesives (a silicone adhesive (adhesive A), an epoxy resin adhesive (adhesive B), and a vinyl acetate resin adhesive (adhesive C)) were used, and adhesive test pieces A, B, and C were prepared.

Adhesive

[0091] A: silicone adhesive (Super X No. 8008 black: Cemedine Co., Ltd.) (main component: acrylic-modified silicone resin)
B: epoxy resin adhesive (3M Panel Bond Mini 38315N: 3M) (main component: epoxy resin, curing agent: amine-based resin)
C: vinyl acetate resin adhesive (concrement CA-131: Cemedine Co., Ltd.) (component: vinyl acetate resin 25%, inorganic substance 50%, organic solvent 25%)

(3) Evaluation Test for Effect of Limiting Decrease in Durability

[0092] (i) Test pieces A, B, and C are immersed in individual microbicidal compositions kept at 40° C. and allowed to stand for 16 hours.
(ii) After 16 hours, each test piece is taken out from the immersion solution, rinsed with distilled water, and allowed to stand at room temperature to naturally dry.
(iii) After drying, the appearance of the adhesive on each test piece is visually observed.
(iv) The effect of limiting a decrease in durability is evaluated based on the properties of adhesives on four items: “whether the color has changed: Yes (B)/No (A),” “whether bubbling (bubbles) has occurred: Yes (B)/No (A),” “whether a gap and peeling are present: Yes (B)/No (A), and “whether cracks are present: Yes (B)/No (A).”

(4) Evaluation Results of Effect of Limiting Decrease in Durability

[0093] Table 4 shows the results in regards to the effect of glycine and the impact of hydrogen peroxide in microbicidal compositions.

TABLE-US-00004 TABLE 4 Concentration (mass %) in Microbicidal Composition (Aqueous Solution) Example Comparative Example Component 2-1 2-2 2-3 2-4 2-1 2-2 2-3 Peracetic Acid 0.4 0.4 0.3 0.5 0.4 0.4 0.4 Hydrogen Peroxide 0.6 0.6 0.45 0.75 0.6 5 5 Glycine 0.48 0.48 0.36 0.6 0.0 0.48 0.48 Hydrogen Phosphate*.sup.1 0.0 0.12 0.09 0.15 0.0 0.0 0.12 Chelating Agent*.sup.2 0.0 0.06 0.045 0.075 0.0 0.0 0.06 Stabilizer*.sup.3 0.0 0.4 0.3 0.5 0.0 0.0 0.4 pH Adjuster*.sup.4 Moderate Moderate Moderate Moderate Moderate Moderate Moderate Amount Amount Amount Amount Amount Amount Amount Total with Distilled Water 100 100 100 100 100 100.0 100 pH of Microbicidal Composition 6 6 6 6 6 6 6 Silicone Evaluation Change in A A A A A A A Adhesive Item Color Bubbling A A A A B B B Cracking A A A A A A A Gap/Peeling A A A A A B A Epoxy Resin Change in A A A A A A A Adhesive Color Bubbling A A A A A A A Cracking A A A A A A A Gap/Peeling A A A A A B B Vinyl Change in A A A A A A A Acetate Color Resin Bubbling A A A A B B B Adhesive Cracking A A A A A A A Gap/Peeling A A A A A A A Determination A A A A B B B *.sup.1Dipotassium Hydrogen Phosphate *.sup.2Tetrasodium Hydroxyethane Diphosphonate *.sup.3Dipropylene Glycol *.sup.4Potassium Hydroxide or Citric Acid

[0094] As shown in Table 4, the results indicate that the addition of glycine limits a decrease in durability (in particular, bubbling) of, in particular, the silicone adhesive or vinyl acetate resin adhesive due to peracetic acid and hydrogen peroxide (Examples 2-1 and 2-2 and Comparative Example 2-1). However, the silicone adhesive, epoxy resin adhesive, and vinyl acetate resin adhesive all had bubbling or a gap and peeling despite the glycine contained and were confirmed to have decreased (changed) durability, when the concentration of hydrogen peroxide was as high as 5% or more (Comparative Examples 2-2 and 2-3).

[0095] Table 5 shows the results in regards to the impact of the concentration of peracetic acid, hydrogen peroxide, and glycine in microbicidal compositions.

TABLE-US-00005 TABLE 5 Concentration (mass %) in Microbicidal Composition (Aqueous Solution) Comparative Example Example Component 3-1 3-2 3-3 3-4 3-5 3-1 Peracetic Acid 0.5 0.6 0.7 0.8 0.9 1 Hydrogen Peroxide 0.75 0.9 1.05 1.2 1.35 1.5 Glycine 0.6 0.72 0.84 0.96 1.08 1.2 pH Adjuster*.sup.1 Moderate Amount Moderate Amount Moderate Amount Moderate Amount Moderate Amount Moderate Amount Total with Distilled Water 100 100 100 100 100 100 pH of Microbicidal Composition 6 6 6 6 6 6 Silicone Eval- Change in Color A A A A A A Adhesive uation Bubbling A A A A A A Item Cracking A A A A A A Gap/Peeling A A A A A B Epoxy Resin Change in Color A A A A A A Adhesive Bubbling A A A A A A Cracking A A A A A A Gap/Peeling A A A A A A Vinyl Acetate Change in Color A A A A A B Resin Bubbling A A A A A B Adhesive Cracking A A A A A A Gap/Peeling A A A A A A Determination A A A A A B *.sup.1Potassium Hydroxide or Citric Acid

[0096] The results indicate that the microbicidal composition 5 with a peracetic acid concentration of 1.0%, a hydrogen peroxide concentration of 1.5%, and a glycine concentration of 1.2% (Comparative Example 3-1) slightly decreased the durability of the silicone adhesive and vinyl acetate resin adhesive, but did not decrease the durability of the epoxy resin adhesive. This 10 suggests that the peracetic acid concentration and the hydrogen peroxide concentration at which the action of limiting a decrease in durability of these adhesives can be brought about are respectively less than 1.0% and less than 1.5%. As noted above, an aqueous solution with a peracetic acid concentration of 1.0% or more and a hydrogen peroxide concentration of 1.5% or more did not sufficiently limit a decrease in durability of adhesives even when glycine was added in an amount of 1.2%. However, for example, an aqueous solution with a peracetic acid concentration of 1.35% and a hydrogen peroxide concentration of 1.08% as in Example 3-5 can provide the same effect as that in Example 3-5, even when containing more than 1.2% of glycine. This suggests that for an aqueous solution with a peracetic acid concentration of less than 1.0% and a hydrogen peroxide concentration of less than 1.5%, there is no upper limit of the amount of glycine from the standpoint of the effect of limiting a decrease in durability of adhesives.

[0097] Table 6 (silicone adhesive), Table 7 (epoxy resin adhesive), and Table 8 (vinyl acetate resin adhesive) show the results in regards to the impact of the pH of microbicidal compositions.

TABLE-US-00006 TABLE 6 Concentration (mass %) in Microbicidal Composition (Aqueous Solution) Example Component 4-1 4-2 4-3 4-4 4-5 Peracetic Acid 0.2 0.2 0.2 0.2 0.2 Hydrogen Peroxide 0.3 0.3 0.3 0.3 0.3 Glycine 0.24 0.24 0.24 0.24 0.24 pH Adjuster*.sup.1 Moderate Moderate Moderate Moderate Moderate Amount Amount Amount Amount Amount Total with Distilled Water 100 100 100 100 100 pH of Microbicidal Composition 3 4 5 6 7 Silicone Evaluation Change A A A A A Adhesive Item in Color Bubbling A A A A A Cracking A A A A A Gap/Peeling A A A A A Determination A A A A A *.sup.1Potassium Hydroxide or Citric Acid

TABLE-US-00007 TABLE 7 Concentration (mass %) in Microbicidal Composition (Aqueous Solution) Example Component 5-1 5-2 5-3 5-4 5-5 5-6 Peracetic Acid 0.6 0.6 0.6 0.6 0.6 0.6 Hydrogen Peroxide 0.9 0.9 0.9 0.9 0.9 0.9 Glycine 0.72 0.72 0.72 0.72 0.72 0.72 pH Adjuster*.sup.1 Moderate Moderate Moderate Moderate Moderate Moderate Amount Amount Amount Amount Amount Amount Total with Distilled Water 100 100 100 100 100 100 pH of Microbicidal Composition 2 3 4 5 6 7 Epoxy Resin Evaluation Change A A A A A A Adhesive Item in Color Bubbling A A A A A A Cracking A A A A A A Gap/Peeling A A A A A A Determination A A A A A A *.sup.1Potassium Hydroxide or Citric Acid

TABLE-US-00008 TABLE 8 Concentration (mass %) in Microbicidal Composition (Aqueous Solution) Example Component 6-1 6-2 6-3 6-4 6-5 Peracetic Acid 0.2 0.2 0.2 0.2 0.2 Hydrogen Peroxide 0.3 0.3 0.3 0.3 0.3 Glycine 0.24 0.24 0.24 0.24 0.24 pH Adjuster*.sup.1 Moderate Amount Moderate Amount Moderate Amount Moderate Amount Moderate Amount Total with Distilled Water 100 100 100 100 100 pH of Microbicidal Composition 3 4 5 6 7 Vinyl Eval- Change in Color A A A A A Acetate Resin uation Bubbling A A A A A Adhesive Item Cracking A A A A A Gap/Peeling A A A A A Determination A A A A A *.sup.1Potassium Hydroxide or Citric Acid

[0098] The results indicate that the microbicidal compositions at a pH of 2 to 7, preferably 3 to 7, have properties of limiting a decrease in durability of these adhesives.

[0099] To confirm that the achieved effect is unique to the use of glycine, the same test was performed using, instead of glycine, an equal molar amount of a buffer (acetic acid, trisodium phosphate, dipotassium hydrogen phosphate) disclosed in cited Reference 4 in the formula of Example 3-5. The same test was also performed without using a buffer and glycine as a control. Table 9 shows the results together with the results of Example 3-5.

TABLE-US-00009 TABLE 9 Example Experimental Results Component Control 3-5 1 2 3 Peracetic Acid 0.9 0.9 0.9 0.9 0.9 Hydrogen Peroxide 1.35 1.35 1.35 1.35 1.35 Glycine 0.0 1.08 0 0 0 Acetic Acid 0.00 0.00 0.86 0.00 0.00 Trisodium Phosphate 0.00 0.00 0.00 2.36 0.00 Dipotassium Hydrogen Phosphate 0.00 0.00 0.00 0.00 2.51 pH Adjuster*.sup.1 Moderate Moderate Moderate Moderate Moderate Amount Amount Amount Amount Amount pH of Microbicidal Composition 6 6 6 6 6 Silicone Evaluation Change in Color A A A B B Adhesive Item (Whitening) Bubbling A A A A A Cracking A A A A A Gap/Peeling B A B A B Epoxy Change in Color A A A A A Resin (Whitening) Adhesive Bubbling A A A A A Cracking A A A A A Gap/Peeling A A A A A Vinyl Change in Color A A A A A Acetate Bubbling B A B B B Resin Cracking A A A A B Adhesive Gap/Peeling A A A A A Determination B A B B B *.sup.1Potassium Hydroxide or Citric Acid Note: Evaluation was made based on change in color, bubbling, cracking, and gap or peeling (A or B).

[0100] As shown in the results, acetic acid, trisodium phosphate, and dipotassium hydrogen phosphate, unlike glycine, had no action of limiting a decrease in durability of synthetic adhesives due to the oxidants. This indicates that the effect of limiting a decrease in durability of adhesives due to the oxidants (peracetic acid and hydrogen peroxide) is unique to the use of glycine in combination.

Experimental Example 3: Evaluation of Microbicidal Effect on Various Microorganisms (No. 1)

[0101] The microbicidal effect of the microbicidal composition according to the present invention was evaluated according to an in vitro test based on the European standards by using a general bacterium (Enterococcus faecium ATCC 6057), an acid-fast bacteria (Mycobacterium terrae ATCC 15755), spores (Bacillus subtilis ATCC 19659), and a virus (poliovirus type 1 Sabin strain (LS-c, 2ab strain)/host cells: African green monkey kidney cell JCRB 9013) as microorganisms.

(1) Preparation of Test Composition

[0102] The components listed in Table 10 were dissolved in synthetic hard water to give the concentration and pH indicated in Table 10, thereby preparing test compositions (Examples 7-1 to 7-3).

(2) Preparation of Microbial Solutions

(a) General Bacteria

[0103] A glycerol stock of Enterococcus faecium ATCC 6057 was inoculated in a trypticase soy agar medium (“TSA medium” below) and cultured at 37° C. After culture, a diluent (0.85% NaCl and 0.1% tryptone peptone-containing aqueous solution, “diluent 1” below) was added, and the medium was scraped. The obtained microbial solution was placed in a 50-mL centrifuge tube, and 5 g of sterile glass beads was added, followed by stirring for 1 minute. After stirring, only the microbial solution was collected in another centrifuge tube. After centrifugation, the supernatant was removed, and the microbial solution was resuspended with the diluent.

(b) Acid-Fast Bacterium

[0104] A glycerol stock of Mycobacterium terrae ATCC 15755 was inoculated in a medium (Mycobacteria 7H11 agar+10% OADC enrichment medium, “7H11 medium” below) and cultured at 37° C. After culture, the bacterium was scraped off and collected in a 50-mL centrifuge tube containing sterile glass beads. Sterile distilled water was added to the tube, and the mixture was stirred and diluted accordingly. The diluted mixture was allowed to stand, and then the microbial solution in the middle layer was collected.

(c) Spores

[0105] A glycerol stock of Bacillus subtilis ATCC 19659 was inoculated in an NB medium (Nutrient Broth No. 2), cultured at 37° C., and passaged into a sporulation medium plate, followed by culture at 37° C. After culture, sterile water was poured to scrape off the bacterium, and the scraped bacterium was then placed in a 50-mL centrifuge tube containing sterile glass beads and stirred, followed by filtration through sterile gauze. After centrifugation, an operation of washing the filtrate with sterile water and centrifugation of the filtrate was performed three times, followed by resuspension with sterile water. The resulting product was heated at 80° C. for 15 minutes, thereby preparing a microbial solution.

(d) Virus

[0106] A cryopreserved solution of poliovirus type 1 Sabin strain was diluted and inoculated in a cell culture plate. An FBS-containing MEM medium was added, and culture was performed at 37° C. in 5% CO.sub.2, followed by scraping the cells to collect the culture broth. The collected culture broth was subjected to a freeze-thaw cycle at −80° C. three times, and the obtained culture broth was centrifuged to collect the supernatant, thereby preparing a microbial solution.

(3) Evaluation Test for Microbicidal Effect

(a) General Bacteria: EN 13727:2012/Dirty Conditions

[0107] (i) A test composition kept at 35° C. beforehand, a microbial solution, and an interfering substance under dirty conditions (3% BSA+3% red blood cells: the same below) are mixed in a ratio of 8:1:1, and allowed to act at 35° C.
(ii) After action for 5 minutes, a neutralizer (0.1% sodium thiosulfate, catalase) is added to inactivate the mixture solution.
(iii) The inactivated mixture solution is applied to the surface of a TSA medium and cultured at 37° C.
(iv) After one day from culture, the number of microorganisms is counted.
(v) In accordance with the requirements of EN 13727:2012, a log reduction value of microbial counts before and after the test being 6 Log.sub.10 or higher is determined to be “A: having an effective microbicidal effect,” and otherwise determined to be

[0108] “B: having no effective microbicidal effect.”

(b) Acid-Fast Bacteria: EN 14348:2005/Dirty Conditions

[0109] (i) A test composition kept at 35° C. beforehand, a microbial solution, and an interfering substance are mixed in a ratio of 8:1:1 and allowed to act at 35° C.
(ii) After action for 5 or 20 minutes, a neutralizer (0.1% sodium thiosulfate, catalase) is added to inactivate the mixture solution.
(iii) The inactivated mixture solution is applied to the surface of a 7H11 medium and cultured at 37° C.
(iv) After three weeks from culture, the number of bacteria is counted.
(v) In accordance with the requirements of EN 14348:2005, a log reduction value of microbial counts before and after the test being 4 Log.sub.10 or higher is determined to be “A: having an effective microbicidal effect,” and otherwise determined to be “B: having no effective microbicidal effect.”

(c) Spores: EN 17126:2018/Dirty Conditions or Clean Conditions

[0110] (i) A test composition kept at 35° C. beforehand, a microbial solution, and an interfering substance under dirty conditions or clean conditions are mixed in a ratio of 8:1:1 and allowed to act at 35° C.
(ii) After action for 5 minutes (dirty conditions) or 20 minutes (clean conditions), a neutralizer (0.1% sodium thiosulfate, catalase) is added to inactivate the mixture solution.
(iii) The inactivated mixture solution is applied to the surface of a TSA medium and cultured at 37° C.
(iv) After one day from culture, the number of spores is counted.
(v) In accordance with the requirements of EN 17126:2018, a log reduction value of microbial counts before and after the test being 4 Log.sub.10 or higher is determined to be “A: having an effective microbicidal effect,” and otherwise determined to be “B: having no effective microbicidal effect.”

(d) Virus: EN 14476:2013/Dirty Conditions

[0111] (i) A test composition and an interfering substance are kept at 35° C. beforehand. A virus solution and a neutralizer (10% FBS-containing MEM+0.5% sodium thiosulfate, catalase) are stored in ice.
(ii) The test composition, the virus solution, and the interfering substance are mixed in a ratio of 8:1:1 and allowed to act at 35° C.
(iii) After action for 5 minutes, the neutralizer is added to inactivate the mixture solution.
(iv) An original liquid (2% FBS-containing MEM) is diluted 10-fold stepwise to prepare diluents. Each diluent is dispensed into 8 wells of a 96-well microtiter plate (FBS-containing MEM medium) in which a host cell (African green monkey kidney cell JCRB9013) has been cultured beforehand, and the cells are cultured at 37° C. in the presence of 5% CO.sub.2 for 1 hour.
(v) After one hour, the medium is removed, and a fresh medium is poured into each well, followed by culture at 37° C. in the presence of 5% CO.sub.2.
(vi) After four days, the viral infectivity (Log.sub.10 TCID.sub.50) is calculated according to the Behrens-Karber method.
(vii) In accordance with the requirements of EN 14476:2013, a log reduction value of viral infectivity before and after the test being 4 Log.sub.10 or higher is determined to be “A: having an effective microbicidal effect,” and otherwise determined to be “B: having no effective microbicidal effect.”

(4) Evaluation Results of Microbicidal Effect

[0112] Table 10 also shows the results.

TABLE-US-00010 TABLE 10 Concentration (mass %) in Test Composition (Aqueous Solution) Example Component 7-1.sup.1) 7-2.sup.1) 7-3.sup.2) Peracetic Acid 0.05 0.07 0.03 Hydrogen Peroxide 0.08 0.11 0.045 Glycine 0.06 0.08 0.036 Dipotassium Hydrogen Phosphate 0.02 0.02 0.01 Tetrasodium Hydroxyethane 0.01 0.01 0.005 Diphosphonate*.sup.1 Dipropylene Glycol*.sup.2 0.05 0.07 0.03 Moderate Moderate Moderate pH Adjuster*.sup.3 Amount Amount Amount Total with Synthetic Hard Water 100 100 100 pH 6 6 6 Microbicidal E. faecium A — — Effect M. terrae A — A B. subtilis A — A Polio virus — A — *.sup.1Chelating Agent *.sup.2Stabilizer *.sup.3Potassium Hydroxide or Citric Acid In the table, “—” indicates that no evaluation was made. .sup.1)Sterilization Conditions: 35° C., Action for 5 minutes .sup.2)Sterilization Conditions: 35° C., Action for 20 minutes

[0113] As shown in Table 10, the microbicidal composition according to the present invention used as a test composition was confirmed to have an effective microbicidal effect on a wide range of microorganisms such as general bacteria, acid-fast bacteria, spores, and viruses. Among them, acid-fast bacteria, especially spores, are microorganisms that are highly resistant to disinfectants. However, because the microbicidal composition according to the present invention was confirmed to have an effective microbicidal effect on these microorganisms even at a low concentration, the microbicidal composition is considered to be a useful microbicidal composition that has an effective microbicidal effect at a low concentration on a wide range of microorganisms.

Experimental Example 4: Evaluation of Microbicidal Effect on Various Microorganisms (No. 2)

[0114] The microbicidal effect of the microbicidal composition according to the present invention was evaluated in the same manner as in Experimental Example 3 by performing microbicidal treatment at 20° C. for 5 minutes according to the test method prescribed in EN 17126:2018 (clean conditions) using spores (B. subtilis) used in Experimental Example 3 as a microorganism.

[0115] Table 11 shows the formula of the test composition (Example 8-1) and its microbicidal effect.

TABLE-US-00011 TABLE 11 Concentration (mass %) in Test Composition (Aqueous Solution) Example Component 8-1 Peracetic Acid 0.20 Hydrogen Peroxide 0.30 Glycine 0.24 pH Adjuster*.sup.1 Moderate Amount Total with Synthetic Hard Water 100 pH 6 Microbicidal B. subtilis A Effect *.sup.1Potassium Hydroxide or Citric Acid

[0116] As shown in Table 11, the microbicidal composition according to the present invention used as a test composition was confirmed to have an effective microbicidal effect on spores that are highly physicochemically resistant in a treatment at room temperature of 20° C.

Experimental Example 5: Microbicidal Effect under Detergent Contamination Conditions

[0117] Microbicidal treatment (disinfection treatment) of critical, semi-critical, and non-critical instruments is generally preceded by washing with a detergent and rinsing with water. However, if these operations are performed inside equipment or if the rinsing is not sufficiently performed after washing, the detergent could be brought into the microbicidal treatment process.

[0118] Thus, the impact of detergent contamination on the microbicidal effect of the microbicidal composition was evaluated, assuming detergent contamination.

(1) Test Method

(a) Evaluation Test 1

[0119] A detergent was added to test compositions adjusted to a pH of 4 (Examples 9-1 to 9-3, Comparative Examples 9-1 to 9-3) so as to give a final concentration of 0.01%, and the test compositions contaminated with the detergent were kept at 35° C. The detergent concentration (0.01%) was determined based on the assumption that contamination with 2% of the entire washing solution for use in the washing step occurred in the microbicidal treatment process. Table 12 shows the formulas of the test compositions.

[0120] Immediately after addition of the detergent (initial) and after 30 minutes of warming, the peracetic acid concentration of the test compositions contaminated with the detergent was measured, and the residual percentage of the peracetic acid was calculated according to the following formula. A residual percentage of 90% or higher was determined to be “A (microbicidal effect under detergent contamination conditions: good), and a residual percentage of less than 90% was determined to be “B (poor).”

The residual percentage(%)=(the peracetic acid concentration after 30 minutes of warming/the initial peracetic acid concentration)×100

(b) Evaluation Test 2

[0121] A detergent was added to test compositions adjusted to a pH of 6 (Example 10-1 and Comparative Example 10-1) so as to give a final concentration of 0.05%, and the test compositions contaminated with the detergent were kept at 35° C. The detergent concentration (0.05%) was determined based on the assumption that contamination with 10% of the entire washing solution for use in the washing step occurred in the microbicidal treatment process. Table 13 shows the formulas of the test compositions.

[0122] As in Evaluation Test 1, immediately after addition of the detergent (initial) and after 30 minutes of warming, the peracetic acid concentration of the test compositions contaminated with the detergent was measured. The residual percentage of the peracetic acid was calculated, and the microbicidal effect under detergent contamination conditions was evaluated.

(2) Test Results

[0123] Tables 12 and 13 show the results of Evaluation Tests 1 and 2.

TABLE-US-00012 TABLE 12 Concentration (mass %) in Test Composition (Aqueous Solution) Example Comparative Example Component 9-1 9-2 9-3 9-1 9-2 9-3 Peracetic Acid 0.03 0.03 0.03 0.03 0.03 0.03 Hydrogen Peroxide 0.045 0.045 0.045 0.045 0.045 0.045 Glycine 0.036 0.036 0.036 0 0 0 pH Adjuster*.sup.1 Moderate Moderate Moderate Moderate Moderate Moderate Amount Amount Amount Amount Amount Amount Total with Distilled Water 100 100 100 100 100 100 pH 4 4 4 4 4 4 Alkaline Detergent A*.sup.2 0.01 — — 0.01 — — Alkaline Detergent B*.sup.3 — 0.01 — — 0.01 — Enzyme Detergent A*.sup.4 — — 0.01 — — 0.01 Determination A A A A A A *.sup.1pH Adjuster: KOH or Citric Acid *.sup.2Alkaline Detergent A: Biotect DX, ultrasonic jet, Seller: Sakura Seiki Co., Ltd. *.sup.3Alkaline Detergent B: EndoQuick, Seller: Olympus Corporation *.sup.4Enzyme Detergent A: Power Quick, Multi-use Enzyme Cleaner, Manufacturer: Saraya Co., Ltd.

TABLE-US-00013 TABLE 13 Concentration (mass %) in Test Composition (Aqueous Solution) Comparative Example Example Component 10-1 10-1 Peracetic Acid 0.03 0.03 Hydrogen Peroxide 0.045 0.045 Glycine 0.036 0 pH Adjuster*.sup.1 Moderate Moderate Amount Amount Total with Distilled Water 100 100 pH 6 6 Enzyme Detergent A*.sup.2 0.05 0.05 Determination A B *.sup.1pH Adjuster: KOH or Citric Acid *.sup.2Enzyme Detergent A: Power Quick, Multi-use Enzyme Cleaner, Manufacturer: Saraya Co., Ltd.

[0124] The results of Evaluation Test 1 (Table 12) indicate that peracetic acid is stable when the pH is acidic; and that if the amount of the incorporated detergent is small, an effective amount of peracetic acid remains irrespective of whether glycine has been added, with no adverse effect on the microbicidal action. The results of Evaluation Test 2 (Table 13) indicate that peracetic acid becomes less stable when the pH value approaches from acidic to neutral, and that incorporation of a detergent further decreases the residual amount of peracetic acid (Comparative Example 10-1); but that even when a detergent is incorporated, an effective amount of peracetic acid remains in a test composition containing glycine (Example 10-2), with no adverse effect on the microbicidal action.

[0125] As noted above, the microbicidal composition according to the present invention, which contains glycine in addition to peracetic acid and hydrogen peroxide, exhibits high stability of peracetic acid, and effective microbicidal action within the pH range from acidic to neutral even if a detergent is incorporated into the composition. Thus, the microbicidal composition according to the present invention is suitably usable in a manual disinfection operation, or, for example, in a disinfection operation using disinfection equipment provided with a disinfection chamber and a disinfectant delivery system.