Antimicrobial composition, antimicrobial liquid, and synthetic resin molded article

Abstract

To provide an antibacterial composition that can exhibit excellent antibacterial properties. [Solution] The antibacterial composition is Monocarboxylic acids (A) which are at least one of lactic acid and its salts, and It contains a polycarboxylic acid (B) represented by the following formula (1). HOOC-R-COOH (1) [In equation (1), R is, single bond, A divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and which may have substituents, or A divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and possibly having substituents.

Description

[Technical Field]

[0001] This disclosure relates to antimicrobial compositions, antimicrobial liquids, and synthetic resin molded articles. [Background technology]

[0002] Bacteria and fungi have strong reproductive and infectious properties, and these can cause serious symptoms in infected individuals. Therefore, there has been a growing demand for antimicrobial compositions to prevent bacterial infections and maintain the hygiene of goods. Antimicrobial compositions can impart antimicrobial properties to goods by being applied to their surface or added to them.

[0003] For example, Patent Document 1 discloses an antibacterial agent containing blueberry leaf extract as an active ingredient. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-172598 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, many bacteria possess extremely high reproductive and infectivity capabilities, and even a small amount of bacteria adhering to an object's surface can cause an infection. Therefore, further improvements in the antibacterial properties of antimicrobial compositions are necessary.

[0006] Therefore, the object of this disclosure is to provide an antimicrobial composition that can exhibit excellent antimicrobial properties. Another object of this disclosure is to provide an antimicrobial liquid and a synthetic resin molded article that can exhibit excellent antimicrobial properties. [Means for solving the problem]

[0007] Antibacterial compositions are Monocarboxylic acids (A) which are at least one of lactic acid and its salts, and It contains a polycarboxylic acid (B) represented by the following formula (1). HOOC-R-COOH (1) [In equation (1), R is, single bond, A divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and which may have substituents, or A divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and possibly having substituents.

[0008] The antibacterial liquid preparation is obtained by dissolving or dispersing the above-mentioned antibacterial composition in a solvent.

[0009] The molded synthetic resin article contains the above-mentioned antibacterial composition and synthetic resin. [Effects of the Invention]

[0010] The above antibacterial composition can exhibit excellent antibacterial properties by using a combination of a predetermined monocarboxylic acid (A) and a polycarboxylic acid (B). By using this antibacterial composition, it is possible to provide an antibacterial liquid agent and a synthetic resin molded article having excellent antibacterial properties. [Modes for carrying out the invention]

[0011] [Antibacterial composition] Antibacterial compositions are Monocarboxylic acids (A) which are at least one of lactic acid and its salts, and It contains a polycarboxylic acid (B) represented by the following formula (1). HOOC-R-COOH (1) [In equation (1), R is, single bond, A divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and which may have substituents, or A divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and possibly having substituents.

[0012] (Monocarboxylic acids (A)) The antibacterial composition contains monocarboxylic acids (A), which are at least one of lactic acid and its salts.

[0013] Examples of the salts of lactic acid in the monocarboxylic acids (A) include alkali metal salts such as sodium salt and potassium salt; and alkaline earth metal salts such as calcium salt and magnesium salt. The monocarboxylic acids (A) may be used alone or in combination of two or more.

[0014] Among them, as the monocarboxylic acids (A), lactic acid, alkali metal salts of lactic acid, and alkaline earth metal salts of lactic acid are preferable, lactic acid, sodium lactate and calcium lactate are more preferable, and calcium lactate is more preferable. By using these monocarboxylic acids (A), the antibacterial property of the antibacterial composition can be improved.

[0015] The monocarboxylic acids (A) may be hydrates or anhydrides. The content (mass) of the monocarboxylic acids (A) in the antibacterial composition is the mass in terms of anhydride. The term "in terms of anhydride" means converting the compound into the mass of the compound in the form of anhydride by removing the mass of the crystal water (water molecules in the hydrate) contained in this compound from the compound.

[0016] (Polycarboxylic acids (B)) The antibacterial composition contains polycarboxylic acids (B) represented by the following formula (1). HOOC-R-COOH (1) [In formula (1), R is a single bond, a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and optionally having a substituent, or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and optionally having a substituent.]

[0017] In formula (1) above, R may be a single bond. When R is a single bond, it means that two adjacent carboxyl groups (-COOH) are directly bonded to each other via R in formula (1). When R is a single bond, an example of the polycarboxylic acid (B) represented in formula (1) above is oxalic acid.

[0018] Furthermore, in formula (1) above, R may be a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and which may have substituents.

[0019] The number of carbon atoms in the divalent aliphatic hydrocarbon group is 1 to 10, but preferably 1 to 8, and more preferably 2 to 5. If the divalent aliphatic hydrocarbon group has substituents, the number of carbon atoms in the substituents is not included in the number of carbon atoms in the divalent aliphatic hydrocarbon group.

[0020] Divalent aliphatic hydrocarbon groups may be saturated or unsaturated. Unsaturated aliphatic hydrocarbon groups are those that contain a carbon-carbon double bond or a carbon-carbon triple bond in their carbon chain. It is preferable that unsaturated aliphatic hydrocarbon groups contain a carbon-carbon double bond in their carbon chain. Furthermore, divalent aliphatic hydrocarbon groups are preferably linear or branched, with linear being preferred.

[0021] A divalent linear aliphatic hydrocarbon group is preferably a group formed by removing one hydrogen atom bonded to each carbon atom at each end of the carbon chain in a linear aliphatic hydrocarbon.

[0022] Examples of divalent aliphatic hydrocarbon groups include alkylene groups and alkenylene groups. Examples of alkylene groups include linear alkylene groups such as methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, and decane-1,10-diyl group; as well as branched alkylene groups such as ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-1,4-diyl group, pentane-2,4-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, and 2-methylbutane-1,4-diyl group. Furthermore, examples of alkenylene groups include linear alkenylene groups such as ethene-1,2-diyl group (vinylene group), propene-1,3-diyl group, 1-butene-1,4-diyl group, 2-pentene-1,5-diyl group, and 3-hexene-1,6-diyl group; and branched alkenylene groups such as ethene-1,1-diyl group, propene-1,2-diyl group, propene-2,3-diyl group, 1-butene-1,2-diyl group, and 1-butene-1,3-diyl group. Among these, linear alkylene groups and linear alkenylene groups are preferred, and ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, octane-1,8-diyl group, and ethene-1,2-diyl group are more preferred.

[0023] The divalent aliphatic hydrocarbon group may have substituents. Examples of substituents include hydroxyl groups and carboxyl groups. There may be one substituent or two or more substituents.

[0024] Furthermore, in formula (1) above, R may be a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and which may have substituents.

[0025] A divalent aromatic hydrocarbon group refers to a group (atomic group) formed by removing (extracting) two hydrogen atoms from an aromatic hydrocarbon. Furthermore, an aromatic hydrocarbon refers to a hydrocarbon containing an aromatic ring structure. An aromatic ring structure is a structure in which carbon atoms are bonded in a ring and possesses aromaticity. That is, an aromatic ring structure is a ring structure that follows Hückel's rule and has (4n+2) π electrons (where n is a natural number). Examples of aromatic ring structures include the benzene ring structure and the naphthalene ring structure.

[0026] The divalent aromatic hydrocarbon group is preferably a group formed by removing one hydrogen atom directly bonded to each of two different carbon atoms constituting the aromatic ring structure of the aromatic hydrocarbon.

[0027] The number of carbon atoms in a divalent aromatic hydrocarbon group is 6 to 20, but preferably 6 to 15, and more preferably 6 to 10. If the divalent aromatic hydrocarbon group has substituents, the number of carbon atoms in the substituents is not included in the number of carbon atoms in the divalent aromatic hydrocarbon group.

[0028] Examples of divalent aromatic hydrocarbon groups include monocyclic or polycyclic divalent aromatic hydrocarbon groups such as phenylene group, dimethylphenylene group, ethylphenylene group, naphthylene group, biphenylene group, and anthracenylene group. Among these, phenylene group, dimethylphenylene group, and ethylphenylene group are preferred, with phenylene group being more preferred.

[0029] The divalent aromatic hydrocarbon group may have substituents. Examples of substituents include hydroxyl groups and carboxyl groups. There may be one substituent or two or more substituents.

[0030] Examples of polycarboxylic acid (B) include the following polycarboxylic acids. Polycarboxylic acid (B) may be used alone or in combination of two or more types.

[0031] In the above formula (1), an example of a polycarboxylic acid (B) in which R is a single bond is oxalic acid.

[0032] Furthermore, examples of polycarboxylic acids (B) in formula (1) above, where R is a divalent aliphatic hydrocarbon group, include malonic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, sebacic acid, suberic acid, and citric acid. Among these, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, sebacic acid, and citric acid are preferred, succinic acid, fumaric acid, malic acid, and citric acid are more preferred, and succinic acid is even more preferred.

[0033] In formula (1) above, polycarboxylic acid (B) in which R is a divalent aromatic hydrocarbon group includes, for example, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, hemiritic acid, trimesic acid, pyromellitic acid, naphthalenedicarboxylic acid, naphthalentricarboxylic acid, biphenyldicarboxylic acid, anthracenedicarboxylic acid, and anthracenetricarboxylic acid. Among these, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, hemiritic acid, trimesic acid, and pyromellitic acid are preferred, and phthalic acid, isophthalic acid, and terephthalic acid are more preferred.

[0034] The polycarboxylic acid (B) is preferably oxalic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, sebacic acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, hemilic acid, trimesic acid, and pyromellitic acid, and more preferably oxalic acid, succinic acid, fumaric acid, malic acid, sebacic acid, citric acid, phthalic acid, isophthalic acid, and terephthalic acid.

[0035] When lactic acid is used as monocarboxylic acid (A), the polycarboxylic acid (B) is preferably a polycarboxylic acid (B) in which R in formula (1) is a single bond or a divalent aliphatic hydrocarbon group, and is preferably oxalic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, and citric acid, with oxalic acid and fumaric acid being more preferred.

[0036] Furthermore, when calcium lactate is used as monocarboxylic acid (A), the polycarboxylic acid (B) is preferably oxalic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, sebacic acid, citric acid, phthalic acid, isophthalic acid, and terephthalic acid, more preferably oxalic acid, succinic acid, fumaric acid, malic acid, sebacic acid, citric acid, and terephthalic acid, and most preferably succinic acid.

[0037] Furthermore, when sodium lactate is used as monocarboxylic acid (A), the polycarboxylic acid (B) is preferably a polycarboxylic acid (B) in which R in formula (1) is a single bond or a divalent aliphatic hydrocarbon group, and is preferably oxalic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, and citric acid, with oxalic acid and citric acid being more preferred.

[0038] Furthermore, when the antibacterial composition is used in a synthetic resin molded article described later, the polycarboxylic acid (B) contained in the antibacterial composition is preferably oxalic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, sebacic acid, citric acid, phthalic acid, isophthalic acid, and terephthalic acid, with oxalic acid, fumaric acid, and phthalic acid being more preferred.

[0039] Polycarboxylic acid (B) may be in hydrate or anhydrous form. The content (by mass) of polycarboxylic acid (B) in the antimicrobial composition shall be expressed as the mass on an anhydrous basis.

[0040] The content of polycarboxylic acid (B) in the antimicrobial composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, more preferably 10 parts by mass or more, more preferably 50 parts by mass or more, more preferably 100 parts by mass or more, more preferably 300 parts by mass or more, more preferably 500 parts by mass or more, more preferably 1000 parts by mass or more, more preferably 1500 parts by mass or more, and more preferably 1750 parts by mass or more, per 100 parts by mass of monocarboxylic acid (A). Furthermore, the content of polycarboxylic acid (B) in the antibacterial composition is preferably 10,000,000 parts by mass or less, more preferably 5,000,000 parts by mass or less, more preferably 1,000,000 parts by mass or less, more preferably 500,000 parts by mass or less, more preferably 300,000 parts by mass or less, more preferably 200,000 parts by mass or less, more preferably 100,000 parts by mass or less, more preferably 40,000 parts by mass or less, more preferably 20,000 parts by mass or less, more preferably 10,000 parts by mass or less, and more preferably 5,000 parts by mass or less, based on 100 parts by mass of monocarboxylic acid (A). By setting the content of polycarboxylic acid (B) within the above range, the antibacterial properties of the antibacterial composition can be improved.

[0041] The antimicrobial composition may contain additives, provided they do not inhibit its antimicrobial properties. Examples of additives include deodorants, surfactants, oils, gelling agents, pH adjusters, antioxidants, fragrances, dyes, and UV absorbers. Additives may be used individually or in combination of two or more.

[0042] In antimicrobial compositions, excellent antimicrobial properties can be achieved by using a combination of predetermined monocarboxylic acids (A) and polycarboxylic acids (B). Therefore, antimicrobial compositions can suppress bacterial growth, kill or reduce bacteria, and so on.

[0043] In particular, the antibacterial composition can exhibit excellent antibacterial properties in a short time. Therefore, even if the antibacterial composition is in contact with bacteria for only a short time, such as a few seconds, it can exhibit high antibacterial properties. From this viewpoint, the contact time between the antibacterial composition and bacteria is preferably 5 seconds or more, more preferably 10 seconds or more, more preferably 20 seconds or more, and more preferably 30 seconds or more. Furthermore, there are no particular restrictions on the contact time between the antibacterial composition and bacteria, but it is preferably 30 minutes or less, more preferably 20 minutes or less, more preferably 10 minutes or less, more preferably 5 minutes or less, and more preferably 1 minute or less.

[0044] Examples of microorganisms include bacteria and fungi. Examples of bacteria include Gram-negative bacteria and Gram-positive bacteria. Examples of Gram-negative bacteria include Escherichia coli, Campylobacter, Pseudomonas aeruginosa, Salmonella, Legionella, and Moraxella. Examples of Gram-positive bacteria include Staphylococcus aureus and Clostridium. Examples of fungi include yeasts and molds. Examples of yeasts include Candida and Rhodotorula. Examples of molds include Red mold and Black mold.

[0045] In particular, Gram-negative and Gram-positive bacteria are preferred, with Escherichia coli, Campylobacter, Salmonella, and Staphylococcus aureus being more preferred, and Escherichia coli and Staphylococcus aureus being even more preferred. The above antimicrobial composition can exhibit particularly excellent antimicrobial activity against these bacteria. In particular, these bacteria have very strong proliferative capabilities, and with conventional antimicrobial compositions, it has been difficult to obtain sufficient antimicrobial activity even when in contact with these bacteria for a long period of time. However, the antimicrobial composition of this disclosure can exhibit excellent antimicrobial activity against these bacteria in a short period of time.

[0046] The method for producing the antimicrobial composition is not particularly limited. For example, an antimicrobial composition can be obtained by mixing monocarboxylic acids (A) and polycarboxylic acids (B), and additives as needed. In this case, the mixing order of each component is not particularly limited.

[0047] [Application] Antimicrobial compositions can be used, for example, to impart antimicrobial properties to articles. For instance, an antimicrobial article can be obtained by incorporating an antimicrobial composition into an article. There are no particular limitations on the articles used in antimicrobial articles, and articles from various fields can be used. Examples of such articles include pharmaceuticals, quasi-drugs, food products, cosmetics, clothing, pesticides, building materials, and paints.

[0048] Furthermore, an antibacterial synthetic resin molded article can be obtained by incorporating an antibacterial composition into the synthetic resin molded article. Preferably, the synthetic resin molded article contains an antibacterial composition and a synthetic resin.

[0049] The content of the antibacterial composition in the molded synthetic resin is preferably 0.0001 parts by mass or more, more preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, more preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and more preferably 30 parts by mass or more, per 100 parts by mass of synthetic resin. Furthermore, the content of the antibacterial composition in the molded synthetic resin is preferably 10,000 parts by mass or less, more preferably 1,000 parts by mass or less, more preferably 500 parts by mass or less, more preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 50 parts by mass or less, and more preferably 45 parts by mass or less, per 100 parts by mass of synthetic resin. By setting the content of the antibacterial composition within the above range, the antibacterial properties of the molded synthetic resin can be improved.

[0050] Conventional known methods can be used for manufacturing the molded synthetic resin article. For example, a method can be used in which an antibacterial composition and a synthetic resin are mixed to obtain a mixture, and then the resulting mixture is molded into a desired shape to obtain the molded synthetic resin article. Alternatively, the antibacterial composition may be used as a masterbatch beforehand when manufacturing the molded synthetic resin article.

[0051] The synthetic resin is not particularly limited and includes olefin resins (propylene resins, ethylene resins, etc.), vinyl chloride resins, polyester resins, acrylic resins, polyamide resins, cellulose resins, styrene resins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, polycarbonate resins, and polyimide resins. The synthetic resin may be used alone or in combination of two or more types.

[0052] By using an antibacterial composition, it is possible to provide a synthetic resin molded article that exhibits high antibacterial activity in a short time. Even if the synthetic resin molded article is only in contact with bacteria for a short time, such as a few seconds, it can exhibit high antibacterial activity. From this viewpoint, the contact time between the synthetic resin molded article and bacteria is preferably 5 seconds or more, more preferably 10 seconds or more, more preferably 20 seconds or more, and more preferably 30 seconds or more. Furthermore, there are no particular limitations on the contact time between the synthetic resin molded article and bacteria, but it is preferably 30 minutes or less, more preferably 20 minutes or less, more preferably 10 minutes or less, more preferably 5 minutes or less, and more preferably 1 minute or less.

[0053] Furthermore, the antibacterial composition can also be used as an antibacterial liquid by dispersing or dissolving it in a solvent. Preferably, the antibacterial liquid contains a solvent and the antibacterial composition dispersed or dissolved in the solvent. Such an antibacterial liquid can be easily applied to or impregnated onto articles.

[0054] The antimicrobial liquid is obtained by dispersing or dissolving the above-mentioned antimicrobial composition in a solvent. Aqueous solvents are preferred as the solvent. Examples include water, as well as alcohols such as methanol, ethanol, isopropyl alcohol, ethylene glycol, and glycerin. One solvent may be used alone, or two or more may be used in combination. Among these, water is preferred as the solvent.

[0055] The water content in the solvent is preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, more preferably 98% by mass or more, and more preferably 100% by mass.

[0056] The content of the antibacterial composition in the antibacterial liquid is preferably 0.000001 parts by mass or more, more preferably 0.00001 parts by mass or more, more preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, more preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, and more preferably 0.05 parts by mass or more, per 100 parts by mass of solvent. Furthermore, the content of the antibacterial composition in the antibacterial liquid is preferably 10,000 parts by mass or less, more preferably 1,000 parts by mass or less, more preferably 100 parts by mass or less, more preferably 50 parts by mass or less, more preferably 25 parts by mass or less, more preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of solvent. From the viewpoint of improving the antibacterial properties of the antibacterial liquid, it is preferable to keep the content of the antibacterial composition within the above ranges.

[0057] By using an antibacterial composition, it is possible to provide an antibacterial liquid agent that exhibits high antibacterial activity in a short time. Even if the antibacterial liquid agent is only in contact with bacteria for a short time, such as a few seconds, it can exhibit high antibacterial activity. From this viewpoint, the contact time between the antibacterial liquid agent and bacteria is preferably 5 seconds or more, more preferably 10 seconds or more, more preferably 20 seconds or more, and more preferably 30 seconds or more. Furthermore, although there are no particular limitations on the contact time between the antibacterial liquid agent and bacteria, it is preferably 30 minutes or less, more preferably 20 minutes or less, more preferably 10 minutes or less, more preferably 5 minutes or less, and more preferably 1 minute or less.

[0058] Antimicrobial liquids can kill or reduce bacteria attached to an article by, for example, applying the antimicrobial liquid to the article's surface. Alternatively, an antimicrobial article can be obtained by applying the antimicrobial liquid to the article's surface, then drying and removing the solvent contained in the antimicrobial liquid to form an antimicrobial coating on the article's surface. Such an antimicrobial article can kill or reduce bacteria attached to its surface, or suppress the growth of bacteria attached to its surface.

[0059] Known application methods can be used to coat the surface of an article with an antimicrobial liquid agent. Examples include the roll coating method, bar coating method, dipping method, spray method, and brush coating method.

[0060] Furthermore, an antibacterial sheet can be obtained by impregnating a base sheet such as paper, knitted fabric, woven fabric, or nonwoven fabric with an antibacterial liquid agent. This antibacterial sheet can be used to clean hands and the body, and for cleaning furniture, various equipment, floors, toilets, and other surfaces. [Examples]

[0061] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0062] (Examples 1-32 and Comparative Example 1) An antibacterial composition was obtained by mixing monocarboxylic acids (A), calcium lactate, sodium lactate, and lactic acid, and polycarboxylic acids (B), succinic acid, fumaric acid, malic acid, oxalic acid, tartaric acid, adipic acid, citric acid, sebacic acid, terephthalic acid, and ascorbic acid, in the amounts (on anhydrous basis) shown in the "Formulation of Antibacterial Composition" column of Tables 1 to 4.

[0063] Next, the antibacterial composition was added to 100 parts by mass of water in the amounts (anhydrous equivalent) shown in the "Formulation of Antibacterial Liquid Agent" column of Tables 1 to 4. These were then mixed to dissolve or disperse the antibacterial composition in water to obtain an antibacterial liquid agent.

[0064] [Antibacterial properties (antibacterial liquid)] The antibacterial activity of the antimicrobial liquid formulations against Staphylococcus aureus, Escherichia coli, Campylobacter, or Salmonella was evaluated according to the following procedure. The results are shown in Tables 1-4.

[0065] [Antibacterial activity against Staphylococcus aureus] As the test bacterium, Staphylococcus aureus (NBRC 12732) was inoculated onto ordinary agar medium and cultured at 35°C for 24 hours. After culturing, the bacterial count was reduced using physiological saline. 8 The test bacterial suspension was prepared by adjusting the concentration to CFU / mL.

[0066] An antimicrobial solution was designated as test sample A. 0.1 mL of the test bacterial suspension was inoculated into 10 mL of test sample A and incubated at 25°C. 10 seconds and 1 minute after inoculation, a 10-fold dilution series of test sample A was prepared in a soybean casein digest liquid medium supplemented with lecithin polysorbate 80. This test solution was inoculated onto soybean casein digest agar medium supplemented with lecithin polysorbate 80 and incubated at 35°C for 78 hours. After incubation, the formed colonies were counted to obtain the viable cell count (CFU / mL) for test sample A 10 seconds and 1 minute after inoculation.

[0067] Furthermore, using phosphate-buffered saline as a control, the same procedure as described above was used to obtain the viable cell count (CFU / mL) for the control 10 seconds and 1 minute after inoculation.

[0068] Then, the antibacterial activity of test sample A 10 seconds and 1 minute after inoculation was calculated based on formulas (I) and (II), respectively, and evaluated according to the following evaluation criteria.

[0069] Antibacterial activity (%) of test sample A 10 seconds after inoculation = 100 × (N C10 -N S10 ) / N C10 (I) N C10 : Number of viable bacteria in the control 10 seconds after inoculation N S10 : Number of viable bacteria in test sample A 10 seconds after inoculation

[0070] Antibacterial property (%) of test sample A 1 minute after inoculation = 100×(N C60 -N S60 ) / N C60 (II) N C60 : Number of viable bacteria in the control 1 minute after inoculation N S60 : Number of viable bacteria in test sample A 1 minute after inoculation

[0071] [Evaluation criteria] A···99% or more. B···90% or more and less than 99%. C···80% or more and less than 90%. D···70% or more and less than 80%. E···60% or more and less than 70%. F···Less than 60%.

[0072] [Antibacterial property against Escherichia coli] Using Escherichia coli (Escherichia coli NBRC 3972) as the test bacterium, the antibacterial property of the antibacterial agent against Escherichia coli was evaluated according to the same procedure as the evaluation method for the antibacterial property against Staphylococcus aureus described above, except that the test liquid was inoculated into "CCDA medium" instead of lecithin·polysorbate 80-added soy bean·casein·digest agar medium and cultured at 37°C for 78 hours, and the test bacterium was inoculated into "CCDA medium" instead of normal agar medium and microaerophilically cultured at 37°C for 48 hours.

[0073] [Antibacterial property against Campylobacter] Using Campylobacter (Campylobacter jejuni JCM 2013) as the test bacterium, the antibacterial property of the antibacterial agent against Campylobacter was evaluated according to the same procedure as the evaluation method for the antibacterial property against Staphylococcus aureus described above, except that the test liquid was inoculated into "CCDA medium" instead of lecithin·polysorbate 80-added soy bean·casein·digest agar medium and cultured at 37°C for 78 hours, and the test bacterium was inoculated into "CCDA medium" instead of normal agar medium and microaerophilically cultured at 37°C for 48 hours.

[0074] [Antibacterial activity against Salmonella] Except for using Salmonella enterica NBRC 100797 as the test bacterium, the antibacterial activity of the antibacterial liquid formulation against Salmonella was evaluated using the same procedure as the method for evaluating antibacterial activity against Staphylococcus aureus described above.

[0075] (Examples 33-35) An antibacterial composition was obtained by mixing calcium lactate as monocarboxylic acid (A) and phthalic acid, fumaric acid, and oxalic acid as polycarboxylic acid (B) in the amounts (on anhydrous basis) shown in the "Formulation of Antibacterial Composition" column of Table 5.

[0076] Next, 43 parts by mass (anhydrous basis) of the antibacterial composition and 100 parts by mass of polyethylene were supplied to an extruder, melt-kneaded at 180°C, and then extruded into a sheet to obtain a synthetic resin molded article (thickness 0.2 cm).

[0077] [Antibacterial properties (synthetic resin molded body)] For the obtained synthetic resin molded articles, Escherichia coli NBRC 3972 was used as the test bacterium, and polyethylene film without antimicrobial composition was used as the unprocessed test piece. The antimicrobial activity value (R) was calculated in accordance with JIS Z2801 (2010) and evaluated based on the following evaluation criteria.

[0078] [Evaluation Criteria] A... The antibacterial activity value (R) was 5.9 or higher. B... The antibacterial activity value (R) was 2.0 or higher and less than 5.9. C... The antibacterial activity value (R) was less than 2.0.

[0079] [Table 1]

[0080] [Table 2]

[0081] [Table 3]

[0082] [Table 4]

[0083] [Table 5] [Industrial applicability]

[0084] The antimicrobial composition disclosed herein exhibits excellent antimicrobial properties. This antimicrobial composition is suitably used, for example, to impart antimicrobial properties to articles or to reduce or remove bacteria adhering to articles. By using the above antimicrobial composition, it is possible to provide an antimicrobial liquid and a synthetic resin molded article that exhibit excellent antimicrobial properties.

Claims

1. Monocarboxylic acids (A) which are at least one of lactic acid and its salts, and An antimicrobial composition comprising a polycarboxylic acid (B) represented by the following formula (1). HOOC-R-COOH (1) [In equation (1), R is, single bond, A divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms and which may have substituents, or A divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and possibly having substituents.

2. The antibacterial composition according to claim 1, wherein monocarboxylic acids (A) are at least one selected from the group consisting of lactic acid, alkali metal salts of lactic acid, and alkaline earth metal salts of lactic acid.

3. The antibacterial composition according to claim 1, wherein monocarboxylic acids (A) are at least one selected from the group consisting of lactic acid, calcium lactate, and sodium lactate.

4. The antimicrobial composition according to claim 1, wherein the polycarboxylic acid (B) comprises at least one selected from the group consisting of oxalic acid, succinic acid, fumaric acid, malic acid, tartaric acid, adipic acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, hemilic acid, trimesic acid, and pyromellitic acid.

5. An antimicrobial liquid preparation obtained by dissolving or dispersing the antimicrobial composition according to any one of claims 1 to 4 in a solvent.

6. An antimicrobial composition according to any one of claims 1 to 4, and a synthetic resin molded article comprising a synthetic resin.

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