A long-lasting antibacterial coating agent made from food ingredients that can be removed with hot water treatment

Abstract

To provide an antibacterial coating agent having both antibacterial effect and safety. [Solution] An antibacterial coating agent comprising an aqueous film-forming agent, one or more antibacterial agents, and a stabilizing solvent, wherein the aqueous film-forming agent is polyvinyl alcohol with guaranteed safety, the antibacterial agents are one or more combinations of food additives or food ingredients that are commonly eaten, and the stabilizing solvent is water.

Description

[Technical Field]

[0001] The present invention relates to an antibacterial coating agent that is safe for humans, has the effect of persistently inhibiting the growth of microorganisms on structures, and has mild peeling conditions for the coating layer. More specifically, the antibacterial coating agent is composed of an antibacterial component that is a food additive or food ingredient extract, a polymer that has high water resistance and unique temperature sensitivity and is commonly consumed, and a stable solvent. That is, this coating agent maintains long-term adhesion even on structures in high-humidity environments, while allowing for controlled peeling under mild conditions using warm water. Furthermore, it has a high non-toxicity value and is safe for living organisms. [Background technology]

[0002] Traditionally, the growth of mold and other microorganisms has been a hygiene and aesthetic problem in places exposed to humid environments, both inside and outside buildings, such as bathrooms, swimming pools, and the walls and ceilings of various factories and warehouses. Mold not only mars the landscape, but also causes structural damage. It also releases spores, odors, and toxins into the air, reducing indoor air quality. It can also cause allergies and respiratory problems, increasing health risks. In particular, in places where maintaining a high level of cleanliness is essential, such as hospitals and food processing facilities, the removal and growth inhibition of not only mold but also bacteria and viruses is crucial. Demand for safe and effective antibacterial and bacterial growth inhibitor coatings to prevent infectious diseases is increasing in nurseries, kindergartens, children's centers, nursing homes, hospitals, and other facilities where infants and elderly people with weak immune systems gather.

[0003] Traditionally, chlorine-based removers have been widely used to remove bacteria, and although they are highly effective, their removal ability is limited to the surface of the structure, so in order to maintain a clean environment, frequent removal work using chlorine-based removers is required on an ongoing basis.

[0004] Chlorine-based bacteria removers rely on chemicals that are harmful to living organisms, such as hypochlorous acid and chlorine, and frequent removal work has been pointed out as posing problems such as potential environmental burdens, safety for humans, and accelerating deterioration of the structures being treated.

[0005] Furthermore, chlorine-based removers are not effective in preventing the re-emergence of bacteria, and are not an effective means in terms of maintaining a clean environment.

[0006] For the reasons stated above, choosing chlorine-based removers as a measure to remove bacteria, such as mold, in large-scale facilities requires significant costs to maintain a clean environment, and sometimes creates a situation where maintaining a clean environment must be partially abandoned.

[0007] The problem of bacterial growth, typified by mold, is particularly serious in food processing plants, where food poisoning and other issues are commonplace. However, the use of removers containing harmful chemicals creates a risk of food contamination separate from the bacteria. As a result, a reduction in bacterial removal work could lead to a decline in food safety. For this reason, there are many restrictions on bacterial control measures in food processing plants, and there is a strong demand for the development of an antibacterial coating agent with proven safety, made from ingredients with a proven food history.

[0008] Furthermore, with regard to the use of sterilization and antibacterial agents in public and medical facilities, there is a demand for antibacterial coating agents that are harmless to the human body yet maintain a high level of sterilization effectiveness for a long period of time. Most conventional sterilization and antibacterial agents rely on synthetic chemical substances, and concerns about the impact these have on the environment and human body mean that a highly safe solution that takes into full consideration the environment, including animals, as well as humans, is needed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2023-004163 A (Antibacterial film) [Patent Document 2] JP 2014-167011 A, JP 2009-527357 A (Removable antibacterial coating composition and method of using the same) [Patent Document 3] JP2015-514758A (Long-lasting surface antibacterial agent and application method) [Patent Document 4] JP 08-092878 (Antibacterial wall covering material) [Patent Document 5] JP-A-08-113898 (Antibacterial wall covering material) [Patent Document 6] JP 08-113899 (Antibacterial wall covering material) [Patent Document 7] JP 08-144472 (Composite building materials) [Patent Document 8] JP 09-100205 A (Antibacterial coating composition) [Patent Document 9] JP 09-132735 A (Antibacterial coating film using antibacterial paint) [Patent Document 10] JP 2000-511887 (Method of using water-stabilized organosilanes) [Patent Document 11] JP 11-228908 A (Antibacterial coating resin composition) [Patent Document 12] JP 2001-081409 A (Antibacterial coating agent, antibacterial agent, and method for preventing hospital infection) [Patent Document 13] JP 2006-213709 A (Water-stabilized organosilane and method of use) [Patent Document 14] Patent Publication No. 2008-308437 (Antibacterial coating agent for application to toilet bowls and antibacterial method for toilet bowls) [Patent Document 15] JP 2009-067849 A (Antibacterial coating film, cooking vessel having the same, and antibacterial coating agent) [Patent Document 16] JP 2009-138288 A (antibacterial agent and antibacterial coating agent) [Patent Document 17] JP 2015-190033 A (Laminate and its manufacturing method, as well as reflectors, mirror films, antibacterial coatings, conductive films, and thermal conductors) [Patent Document 18] JP 2015-191180 A (Laminate and its manufacturing method, as well as reflectors, mirror films, antibacterial coatings, conductive films, and thermal conductors) [Patent Document 19] Re-listed 2016 / 047568 (antibacterial sheet, antibacterial coating, laminate, antibacterial liquid) [Patent Document 20] JP 2017-030823 A (packaging bag) [Patent Document 21] JP 2022-018206 A (Antibacterial composition) [Patent Document 22] JP 2022-080334 A (Antibacterial coating agent and printed matter using the same) [Patent Document 23] Patent Publication No. 7126642 (Antibacterial coating agent and printed matter using it) [Non-patent literature]

[0010] [Non-Patent Document 1] Presentato A, Piacenza E, Scurria A, Albanese L, Zabini F, Meneguzzo F, Nuzzo D, Pagliaro M, Martino DC, Alduina R, Ciriminna R., A New Water-Soluble Bactericidal Agent for the Treatment of Infections Caused by Gram-Positive and Gram-Negative Bacterial Strains., September 8, 2020, Antibiotics (Basel), Vol. 9, No. 9, pp. 586-600. [Non-patent document 2] Presentato A, Scurria A, Albanese L, Lino C, Sciortino M, Pagliaro M, Zabini F, Meneguzzo F, Alduina R, Nuzzo D, Ciriminna R. Superior Antibacterial Activity of Integral Lemon Pectin Extracted via Hydrodynamic Cavitation. ChemistryOpen, May 28, 2020, Vol. 9, No. 5, pp. 628 - 630

Non - Patent Document 3

Non - Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0011] The antibacterial coating agent disclosed in Patent Document 1, like the present invention, uses polyvinyl alcohol as a coating substrate and contains sorbates, dehydroacetates, propionates, acetates, and benzoates as antibacterial ingredients. While some of the described antibacterial agents are registered as food additives, for example, sorbic acid has a usage limit and is not completely safe. Furthermore, propionic acid is a compound with an unpleasant odor. A film composed of polyvinyl alcohol did not exhibit blocking properties when dried in water at 80°C for 30 minutes, and exhibited water resistance and heat resistance, but did not exhibit the properties that allow the antibacterial coating layer of the present invention to be peeled off under specific mild conditions. The antibacterial coating agent disclosed in Patent Document 2 is an organic polymer-based antibacterial coating agent, and it is described that the peeling conditions can be changed by adding additives. However, although the coating agent does not dissolve in water at 20°C, it is easily removed mechanically, and in cold water, the addition of iron chloride is required to maintain stability, and it does not have sufficient strength to maintain an antibacterial coating layer in a living environment. The disinfecting effect of the surface disinfectant disclosed in Patent Document 3 lasts for a maximum of 24 hours, and is not suitable as a method for maintaining a continuously disinfected environment. The antibacterial coating agent disclosed in Patent Document 11 is based on an alkyd-modified acrylic polyol resin that contains heavy metal ions such as silver, copper, zinc, tin, lead, bismuth, mercury, cadmium, or chromium as an antibacterial agent. It requires the use of an organic solvent for application and baking of the coated surface at 50 to 100°C, making it virtually impossible to apply to large areas such as the walls and ceilings of living areas or facilities in operation. The antibacterial coating agent disclosed in Patent Document 12 uses nano-sized silver or copper particles as the antibacterial agent and an acrylic resin as a coating substrate forming component. This antibacterial agent is characterized by its surface treatment by spraying and the durability and water resistance of the coating layer, but requires wiping with alcohol to remove. Therefore, it is not suitable for fabrics or for large areas of walls and ceilings that will require removal and repainting. The antibacterial coating agent disclosed in Patent Document 16 is an antibacterial coating agent made of a chitosan derivative and fatty acid, which uses silver ions as the main antibacterial active ingredient, and is highly safe for the human body, but its range of application is limited to fibers. The antibacterial coating agents disclosed in Patent Documents 4 to 6 have an antibacterial coating layer formed on the surface, but the antibacterial component is an inorganic antibacterial agent and its safety for humans has not been demonstrated. In addition, the antibacterial component is a laminated structure made of polyvinyl chloride, polyethylene terephthalate, etc., which has limitations in antibacterial application to large uneven areas, and is not designed to prevent peeling of the coating layer. In the composite building material disclosed in Patent Document 7, which has an antibacterial coating on the interior side, the antibacterial active ingredient is heavy metal ions such as copper ions and silver ions mixed into resin to form an antibacterial coating layer, but this limits the places where it can be installed and is also limited by the building material. The antibacterial coating composition disclosed in Patent Document 8 is based on silver zeolite as an antibacterial component and is an antibacterial coating agent made of heat- or UV-curable resin. In particular, application by in-mold coating is not very versatile due to the specific equipment required, and is not suitable for antibacterial coating over a large area in terms of reapplication after the antibacterial effect has decreased. In the antibacterial coating film disclosed in Patent Document 9, the antibacterial agent is particles of synthetic silver thiosulfate complex salt, which may change the appearance of the surface to which the antibacterial coating film is applied. In addition, the antibacterial coating film requires the object to be applied to be immersed in a solvent in which the antibacterial particles are suspended, which places a limit on the size of the object to which the antibacterial coating film can be applied. The antibacterial coating agents disclosed in Patent Documents 10 and 13 are organosilane agents containing quaternary ammonium groups with antibacterial properties, and their safety to the human body is unknown. In addition, because they are coating agents based on a polymerization reaction using silanol groups, hydroxyl groups are required on the coating surface, which limits the substances to which they can be applied. The antibacterial coating agent disclosed in Patent Document 14 uses a silane compound as an agent for forming the antibacterial coating layer, and the materials to which it can be applied are limited. In fact, Patent Document 14 is specifically directed to application to toilet bowls. The antibacterial coating agent disclosed in Patent Document 15 is preferably composed of a fluororesin containing silver microparticles as an antibacterial agent, and a polyether ether ketone resin, and its application requires a baking process at 400°C, which limits the materials that can be applied, and it is impossible to reapply it to the entire living area. The antibacterial coating agents disclosed in Patent Documents 17 to 19 are films in which a silver complex or a surfactant is laminated as an antibacterial agent on a resin substrate, and do not form an antibacterial coating layer directly on the target surface, such as the wall of a building. The packaging bag containing an antibacterial agent disclosed in Patent Document 20 is a technology aimed at keeping the inside of the bag sterile, and the antibacterial active ingredient is allyl isothiocyanate, a volatile substance, and is not a technology in which an antibacterial coating layer is formed on a structure afterwards, as in the present invention. The antibacterial composition disclosed in Patent Document 21 is an antibacterial agent consisting of an iodine-based antibacterial agent and metal ions, but does not have any features related to antibacterial coating. The antibacterial agents disclosed in Patent Documents 22 and 23, which are made of binder resins containing metal particles as an antibacterial agent, are said to have substrate adhesion, blocking resistance, and weather resistance, but their properties in high-temperature, high-humidity environments such as bathrooms and food processing factories are not disclosed, and their use is limited to printed matter. The above antibacterial coating agents have problems with either the application method, antibacterial effect, or duration of antibacterial effect. An object of the present invention is to provide an antibacterial coating agent that combines all three of these.

[0012] In this application, "antibacterial" means the ability to kill or inhibit the growth of viruses, bacteria, yeasts, and fungi, and indicates either or both of these effects. [Means for solving the problem]

[0013] The present invention provides an antimicrobial coating agent comprising (1) an aqueous film-forming agent, (2) one or more antimicrobial agents, and (3) a stable solvent, and also discloses a method for controlling microorganisms using the same. The antimicrobial coating agent of the present invention is a convenient combination. [Effects of the Invention]

[0014] The antibacterial coating agent of the present invention exhibits a strong antibacterial effect against a wide range of bacteria and viruses while being safe for people and minimizing the environmental impact.

[0015] In the antibacterial coating agent of the present invention, the antibacterial agent contained in grapefruit seed extract or citrus peel extract such as grapefruit, orange, or lemon acts directly on fungi and other bacteria, effectively inhibiting their growth, so that a single application provides long-lasting antibacterial effects, eliminating the need for frequent antibacterial applications and significantly reducing the effort and cost required for antibacterial treatment.

[0016] The antibacterial coating agent uses a special water- and heat-resistant polyvinyl alcohol as the aqueous film-forming agent, which allows the antibacterial coating to remain on the treated structure for a long period of time, even in environments exposed to water, hot water, and steam (such as factories, warehouses, baths, and pools). This ultimately helps prevent the antibacterial coating ingredients from being mixed in with food during processing or being unintentionally ingested by humans.

[0017] In 2020, Presentato et al. reported that aqueous extracts of grapefruit, orange, and lemon peels contain integropectin, a new antibacterial substance that exhibits strong antibacterial activity against both gram-positive and gram-negative bacteria ([Non-Patent Document 1] to [Non-Patent Document 4]).

[0018] In order to designate polyvinyl alcohol as an additive and establish standards for it, the Ministry of Health, Labour and Welfare requested an opinion from the Food Safety Commission in accordance with Article 24, Paragraph 1, Item 1 of the Food Safety Basic Act (Act No. 48 of 2003) under No. 0622-1 dated June 22, 2022, and the Food Safety Commission issued a notice in No. 379 dated June 7, 2023, stating that "when polyvinyl alcohol is used appropriately as an additive, there are no safety concerns, and it is not necessary to specify an acceptable daily intake." Below are excerpts of the main sections of the additive evaluation report regarding the food health impact assessment.

[0019] Polyvinyl alcohol contains methyl acetate and methanol as impurities, and methyl acetate decomposes into methanol and acetic acid. Therefore, a comprehensive safety assessment (health impact assessment) of "polyvinyl alcohol" was conducted based on knowledge of not only polyvinyl alcohol but also methanol and acetic acid.

[0020] 1. Polyvinyl alcohol Regarding pharmacokinetics, absorption of polyvinyl alcohol after oral administration was very low, and it was thought that the main route of excretion was in the feces. Furthermore, based on the results of excretion tests after intravenous administration, it was thought that when polyvinyl alcohol is absorbed into the body, low molecular weight polyvinyl alcohol is rapidly excreted in the urine, but the higher the molecular weight, the slower the excretion. Polyvinyl alcohol was determined to be non-genotoxic. As a result of examining repeated-dose toxicity and reproductive and developmental toxicity tests, the NOAEL for polyvinyl alcohol was determined to be the maximum dose of 5,000 mg / kg body weight / day, based on the results of a 90-day repeated oral administration test in rats and a rat reproductive toxicity test. The average daily intake of polyvinyl alcohol was estimated to be 590 mg / person / day (11 mg / kg body weight / day) for the general population and 370 mg / person / day (23 mg / kg body weight / day) for children. Polyvinyl alcohol is hardly absorbed in the gastrointestinal tract, and no toxicological findings were observed up to the maximum dose of 5,000 mg / kg body weight / day in a 90-day repeated oral administration test on rats and a reproductive toxicity test on rats. Therefore, it is considered that there are no safety concerns regarding polyvinyl alcohol when it is used appropriately as an additive, and it has been determined that there is no need to specify an ADI.

[0021] 2. Methanol The Food Safety Commission conducted an evaluation in 2019. Since then, no new findings have been identified, and no new studies have been conducted on the pharmacokinetics or toxicity of polyvinyl alcohol. The estimated daily intake of methanol derived from polyvinyl alcohol is 0.15 mg / kg body weight / day for the general population and 0.32 mg / kg body weight / day for children. It is believed that the intake is similar to that of methanol derived from normal dietary sources, and is absorbed, metabolized, and excreted in the body. Taking into account human findings, the intake of methanol in normal dietary habits (2.0 mg / kg body weight / day for the general population and 0.81 mg / kg body weight / day for children), and the ADI (7.1-8.4 mg / kg body weight / day) established by the FDA, the committee concluded that there are no safety concerns regarding methanol derived from polyvinyl alcohol when polyvinyl alcohol is used appropriately as an additive.

[0022] 3. Acetic acid The Food Safety Commission conducted an evaluation in 2017. Since no new findings have been found since then, no new studies have been conducted on the pharmacokinetics and toxicity. Based on the evaluation that the intake from "polyvinyl alcohol" (5.0 mg / person / day for the national average, 3.6 mg / person / day for children) is low compared to the intake from food (130-520 mg / person / day), it was determined that there are no safety concerns regarding acetic acid derived from "polyvinyl alcohol" when "polyvinyl alcohol" is used appropriately as an additive.

[0023] In light of paragraphs

[0017] to

[0021] , it has been determined that there are no safety concerns when "polyvinyl alcohol" is used appropriately, and that there is no need to specify an ADI.

[0024] Even if the antibacterial coating components are ingested by the human body, the antibacterial coating agent of the present invention is extremely safe because it is primarily composed of an antibacterial agent, such as a natural ingredient, grapefruit seed extract or a citrus peel extract, such as grapefruit, orange, or lemon, and an aqueous film-forming agent, such as polyvinyl alcohol, which is guaranteed to be safe. Therefore, there is significantly less concern about contamination with bacteria removers or antibacterial coating materials, even in food processing plants, for example. In other words, the antibacterial coating agent of the present invention can be used safely in places and situations where sterilization work has previously been avoided due to the toxicity of cleaning detergents and antibacterial coating agents.

[0025] Furthermore, the antibacterial coating layer formed from the antibacterial coating agent of the present invention does not require any harmful special chemicals, can be easily removed with warm water and slight friction, and can be easily reapplied, which reduces the burden on the environment and contributes to protecting the health of workers. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a diagram showing experimental results in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0027] (Antibacterial coating agent) The present invention is an antimicrobial coating agent that includes an aqueous film-forming agent, one or more antimicrobial agents, and a stable solvent.

[0028] The aqueous film-forming agent constituting the antibacterial coating agent of the present invention is polyvinyl alcohol, which is guaranteed to be safe. The antibacterial agent is one or a combination of food additives or food ingredients that are commonly eaten. The stable solvent is water.

[0029] Examples of antibacterial agents include grapefruit seed extracts and extracts of citrus peels such as grapefruit, orange, and lemon. A specific example of grapefruit seed extract is "Desfan-10" (sold by Adept Co., Ltd.). "Desfan-10" is a natural disinfectant and antibacterial agent (grapefruit seed extract) extracted from grapefruit seeds and is also approved as a food additive. Other examples include extracts of citrus peels commonly consumed, such as grapefruit, lemon, and orange. These extracts contain integropectin, a type of pectin that encapsulates polyphenols, flavonoids, and terpenes that exhibit antibacterial activity. The antibacterial agent may be composed of such food additives or extracts of commonly consumed food ingredients, either alone or in combination.

[0030] In this embodiment, the antibacterial coating agent is, for example, composed of 68.5 to 98% by mass of water, 1 to 20% by mass of grapefruit seed extract or citrus peel extract such as grapefruit, orange, or lemon, and 0.5 to 30% by mass of polyvinyl alcohol. Another example is a composition ratio of 88 to 96% by mass of water, 3 to 8% by mass of grapefruit seed extract or citrus peel extract, and 1 to 4% by mass of polyvinyl alcohol.

[0031] Polyvinyl alcohol (PVA), an aqueous film-forming agent, is widely used as a pharmaceutical additive in tablets, capsules, and other similar pharmaceutical formulations. The safety of polyvinyl alcohol for the human body has already been confirmed, and its use as a food additive is currently being investigated by the Food Safety Commission. Thus, the aqueous film-forming agent used in the present invention is composed of polyvinyl alcohol, which is guaranteed to be safe.

[0032] Polyvinyl alcohols that can be used in the present invention include general-purpose polyvinyl alcohols and modified products. It is preferable to use special polyvinyl alcohols that are water-resistant and heat-resistant. The use of such special polyvinyl alcohols allows construction in locations exposed to water, hot water, and steam (e.g., factories, warehouses, bathrooms, swimming pools, etc.).

[0033] Specific examples of water-resistant and heat-resistant special polyvinyl alcohols include those with a degree of saponification of 80 mol% to 99.99 mol% and a degree of polymerization of 100 to 5000, and more preferably those with a degree of saponification of 98 mol% or more and a degree of polymerization of 200 to 3500. By using such special polyvinyl alcohols as components of antibacterial coating agents, it is possible to form water-resistant and heat-resistant antibacterial coatings. For example, if antibacterial construction is performed in locations frequently exposed to water, hot water, and steam (factories, warehouses, baths, swimming pools, etc.), and a water-resistant and heat-resistant antibacterial coating is formed, the antibacterial coating will not easily come off even with repeated exposure to water or hot water, allowing the antibacterial effect to be maintained for a long period of time.

[0034] Furthermore, the polyvinyl alcohol used in this embodiment has excellent moisture resistance, gas barrier properties, and adhesive properties, allowing the antibacterial coating to be firmly fixed to the application surface and maintain a high antibacterial effect for a long period of time, thereby improving antibacterial performance in a variety of environments.

[0035] (Microbial control method using antibacterial coating agent) As an example of a microbial control method, we will explain antifungal application using the above-mentioned antibacterial coating agent. In the antifungal application, an antibacterial coating agent composed of polyvinyl alcohol, grapefruit seed extract, and water is used as an example of the antibacterial coating agent.

[0036] When applying anti-mold coating, first remove mold from the application surface, such as the wall or ceiling. In this process, mold is removed using a commercially available mold remover, and then the mold remover is thoroughly washed off with water. Next, the application surface is allowed to dry completely.

[0037] Next, apply the antibacterial coating to the dry surface (the surface to be protected from mold). When applying using a hand spray, put the antibacterial coating in a spray bottle and spray it evenly over the surface, then spread it thinly using a cloth, sponge, roller, or brush soaked in the antibacterial coating. This forms a film of the antibacterial coating on the surface.

[0038] The thickness of this coating is not particularly limited, but for example, a thickness of several μm to several hundred μm will be sufficient to achieve the intended effect, and since it is colorless and transparent, the natural appearance of the applied surface can be maintained even after application, and the aesthetics will not be impaired.

[0039] The antibacterial thin film formed on the application surface contains dispersed antibacterial agents made from grapefruit seed extract and citrus peel extract, such as grapefruit, orange, and lemon, on the surface and inside, which provide a sustained effect of suppressing the growth of mold.

[0040] Furthermore, by covering a surface with an antibacterial coating containing grapefruit seed extract or citrus peel extract, such as grapefruit, orange, or lemon, dispersed therein, the antibacterial coating not only acts against putrefactive bacteria remaining on the surface, but also suppresses the spread of bad odors and the like due to the coating effect of polyvinyl alcohol. In other words, the antibacterial coating formed by this embodiment has not only an antifungal effect but also an antiodor effect.

[0041] The tool used to apply the antibacterial coating agent is not particularly limited, and for example, any one or a combination of two or more of a sprayer, hand sprayer, cloth, sponge, roller, brush, etc. As the sponge, for example, a paint sponge can be used.

[0042] If dirt or microorganisms are found on the antibacterial thin film, the dirt and microorganisms can be easily washed away along with the antibacterial coating by rubbing with a brush or the like while pouring warm water of 40°C or higher over the surface. The surface is then allowed to dry completely, and the antibacterial coating agent is then applied to the surface. Therefore, once the antibacterial coating agent of the present invention is applied, the antibacterial coating can be easily applied without the need for subsequent cleaning with chlorine-based liquids or the like.

[0043] The antibacterial coating material of the present invention can be applied to any material, including glass such as windows, pulp and synthetic fibers such as wallpaper, synthetic resins such as air conditioners and trash cans, wood such as desks and chairs, fabric materials such as curtains and mattresses, leather materials such as bags and shoes, clay for tableware, metals such as watches and accessories, and ceramic materials such as tiles.

[0044] The microorganisms that can be controlled using the antibacterial coating agent of the present invention are not limited to molds, but can be used to control all kinds of microorganisms including viruses.

[0045] In the examples described below, a sports gym is cited as an example of a construction target, but the application of the present invention is not particularly limited, and it can be widely used in public facilities, hospitals, nursing homes, factories, home environments, etc.

[0046] Next, specific examples of the present invention will be described. [Example]

[0047] (Water resistance and temperature sensitivity of polyvinyl alcohol) The water resistance of the polyvinyl alcohol used in this antibacterial coating was evaluated by its melting time. Films 40–70 μm thick were prepared for polyvinyl alcohol 1 (PVA1) (99.25 mol% saponification degree, 230 degree of polymerization), polyvinyl alcohol 2 (PVA2) (98.46 mol% saponification degree, 250 degree of polymerization), and polyvinyl alcohol 3 (PVA3) (98.35 mol% saponification degree, 300 degree of polymerization) and dried at 20°C and 65% relative humidity. The films were cut into 1 cm squares, impaled on a hanging hook, and immersed in water at 20°C and 40°C. The melting time was recorded, and the results shown in Figure 1 were obtained. Compared to PVA2 and PVA3, the melting time for PVA1 at 20°C increased significantly with increasing film thickness. Furthermore, as shown in Table A, the melt-cutting time of a 50 μm thick film at 20°C is approximately twice that of PVA2 and PVA3. These results indicate that the coating layer formed on the applied surface of PVA1 has high water resistance. On the other hand, as shown in Table A, the melt-cutting time of PVA1 at 40°C is only 9 seconds different from that of PVA2 and PVA3. This result indicates that the coating layer formed with PVA1 can be easily peeled off if it is subjected to continuous contact with water at 40°C or above.

[0048] [Table A] [Example]

[0049] (Preparation of antibacterial coating agent containing grapefruit seed extract) 1 L each of the nine types of antibacterial coating agents 1 to 9 shown in Table 1 and a comparative coating agent containing no antibacterial agent was prepared. Antibacterial coating agents 1 to 9 were prepared by mixing and stirring water, grapefruit seed extract, and polyvinyl alcohol (PVA) in the ratios shown in Table 1. The grapefruit seed extract used was "Desfan-10" (sold by Adept Co., Ltd.). The specifications (saponification degree, polymerization degree) of the polyvinyl alcohol used were as shown in Table 1.

[0050] [Table 1] [Example]

[0051] (Preparation of antibacterial coating agent containing grapefruit peel extract) Organically grown grapefruit from Japan was thoroughly washed with water and then the peel was removed using a knife to a thickness of approximately 2 mm. The peel was immediately frozen at -25°C. 15 mL of water was added to 5 g of freeze-dried peel, and the mixture was left to stand in the dark. After 24 hours, the supernatant was collected and freeze-dried. The solid residue was dissolved in water to prepare a 100 mg / mL grapefruit peel extract aqueous solution. This peel extract aqueous solution was used to prepare 1 L each of antibacterial coating agents 10 to 18, as shown in Table 2.

[0052] [Table 2] [Example]

[0053] (Test to verify anti-mold effect) The subject of the experiment was a bathroom ceiling in a sports gym. The gym's bathroom, where the work was being done, was exposed to hot water and steam, and mold had grown over a wide area on the bathroom ceiling. The mold-growing areas on the bathroom ceiling were divided into 20 work areas (areas 1 to 20), and the experiment was carried out using the following procedure.

[0054] First, mold in each experimental area of the bathroom ceiling was removed using a commercially available chlorine-based mold remover, and then thoroughly rinsed with water.

[0055] Next, of the 20 experimental areas, antibacterial coating agent 1 was applied thinly and evenly to the first area using a sponge soaked in it, and then thoroughly dried to form a coating. Using the same procedure, antibacterial coating agents 2 to 18 were applied to the second to eighteenth areas. The comparative coating agent and negative control agent were applied to the nineteenth and twentieth areas, respectively, using the same procedure.

[0056] Table 3 shows the results of observations of mold growth in each construction area after six months and one year under normal bathroom usage conditions, where the area is exposed to hot water and steam.

[0057] [Table 3]

[0058] Six months after application of the antibacterial coating, the treatment areas were checked for mold growth. In the treatment areas where antibacterial coatings 1-9 were applied, no mold recurrence was visually observed in antibacterial coatings 1-3, which combined polyvinyl alcohol with a saponification degree of 99.25 mol% and a polymerization degree of 230 with grapefruit seed extract. On the other hand, mold growth was confirmed in antibacterial coatings 4-6, which combined polyvinyl alcohol with a saponification degree of 98.46 mol% and a polymerization degree of 250 with grapefruit seed extract, and antibacterial coatings 7-9, which combined polyvinyl alcohol with a saponification degree of 98.35 mol% and a polymerization degree of 300 with grapefruit seed extract. Similarly, antibacterial coatings 10-18, which combined grapefruit peel extract, and antibacterial coatings 10-12, which combined polyvinyl alcohol with a saponification degree of 99.25 mol% and a polymerization degree of 230 with grapefruit seed extract, showed favorable results in suppressing mold recurrence. In the 19th area, where no mold growth was observed, and where only the polyvinyl alcohol used in antibacterial coatings 1-3 and 10-12 was applied, mold growth was observed. These results revealed that the combination of a specific polyvinyl alcohol with grapefruit seed extract or grapefruit peel extract is important for achieving a sustained mold growth inhibitory effect. In the 20th area, where only water was applied, mold growth was observed at the same rate as before the experiment began, indicating that commercially available chlorine-based mold removers cannot be expected to have a sustained mold suppression effect.

[0059] The bathroom ceiling at the experimental site was left for another six months (a total of one year), and the mold-inhibiting effects of antibacterial coatings 1-18 were observed. A small amount of scattered mold was confirmed in antibacterial coatings 1 and 10. However, the degree of mold growth was far less than in the areas treated with the comparative coating and negative control six months after the start of the experiment. Furthermore, no mold growth was observed in the areas treated with antibacterial coatings 2, 3, 11, and 12. The surfaces treated with antibacterial coatings 4-9 and 13-18 showed mold growth to the same extent as the negative control. This is thought to be due to the low water resistance of the polyvinyl alcohol used, which caused the antibacterial coating to peel off during bathroom use.

[0060] Next, when the areas treated with antibacterial coating agents 1 and 10, where mildew had grown, were gently scrubbed with a brush while pouring warm water at approximately 42°C, the mildew was easily removed. This was thought to be because the antibacterial coating layer peeled off due to the friction from the brush in addition to the heat from the warm water. In other words, it was shown that in areas where an appropriate antibacterial coating agent had been applied, mildew could be removed with warm water and gentle friction, without the need for conventional chlorine-based mildew removers.

[0061] In the above mold removal work, simply pouring hot water at approximately 42°C was insufficient to remove the mold. This was thought to be due to the water resistance of the polyvinyl alcohol used in antibacterial coating agents 1 and 10. In other words, in environments where the antibacterial coating agent is frequently exposed to hot water and steam, such as walls and ceilings where no physical friction occurs on the surface where the antibacterial coating agent is applied (e.g., food processing factories, warehouses, swimming pools, bathrooms, etc.), the antibacterial coating layer does not easily peel off or dissolve, but rather maintains its coating state and exhibits antibacterial effects for a long period of time.

[0062] (Summary of experimental results) The above results demonstrate that the antibacterial coating agent of the present invention forms an antibacterial coating on the surface and exhibits a long-term mold-inhibiting effect. Furthermore, it was confirmed that even if mold grows on the antibacterial coating, it can be easily removed with warm water and gentle friction, without relying on mold removers that are harmful to the human body and have a large environmental impact. [Example]

[0063] Based on "JIS Z2801 Antibacterial processed products - Antibacterial test method, antibacterial effect," the antibacterial properties of the coating layer formed by the antibacterial coating agent of the present invention were evaluated against Staphylococcus aureus (NBRC12732), Escherichia coli (NBRC3972), and methicillin-resistant Staphylococcus aureus (MRSA IID1677).

[0064] (Preparation of test specimen) A 5 cm x 5 cm x 1 cm piece of plastic was used as the test piece. The surface of the test piece was treated with antibacterial coating agent 3 (Table 1) and antibacterial coating agent 10 (Table 2) of the present invention. The treatment was carried out using the sponge method described above.

[0065] (Test Procedure) A test piece coated with an antibacterial coating and an untreated test piece were placed in a petri dish, and 0.4 ml of test bacteria solution was dropped onto them. To prevent the test bacteria solution from drying out, a film (5cm x 5cm) that does not have antibacterial activity was placed over the dish, and the lid was then closed. The petri dishes were incubated at 35°C and 90% RH or higher for 24 hours. After 24 hours, 10 ml of SCDLP medium was added to wash out the test bacteria from the film and test specimen. The number of bacteria in the washout solution was measured using the agar plate culture method. The antibacterial activity value was calculated based on the following formula. Antibacterial activity value = log(1cm of untreated test piece) 2 Number of viable bacteria after incubation per 1cm of antibacterial treated specimen) - log( 2 (Number of viable bacteria after incubation per 100ml)

[0066] (Experimental results) Table 4 shows the results for antibacterial coating agents 1 and 10.

[0067] [Table 4]

[0068] From the above results, it was found that the coating layer formed using the antibacterial coating agent of the present invention exhibited bactericidal or bacteriostatic effects against Staphylococcus aureus, Escherichia coli, and MRSA. In other words, the antibacterial coating agent of the present invention is effective as a disinfectant for infectious disease control, and can be used for infectious disease control in, for example, hospitals, nursing homes, etc. [Example]

[0069] The antibacterial coating agent of the present invention was applied to a curtain to evaluate the antibacterial activity and the durability of the antibacterial coating formed on the surface of the curtain.

[0070] (Test Method) 1. Test Specimen Preparation The fabric of the fire curtain was cut into circular test pieces with a diameter of 25 mm, and the antibacterial coating agent of the present invention (corresponding to Example 2, antibacterial coating agent 3 in Table 1) was applied to the test pieces.

[0071] The antibacterial coating agent used had the following composition: Grapefruit seed extract: 8 wt% PVA (saponification degree 99.25 mol%, polymerization degree 230): 4 wt% ·Water: 88 wt%

[0072] The test piece was treated by spraying the antibacterial coating agent evenly five times from a distance of 20 cm, and then drying it at room temperature for 24 hours in the dark. The amount of adhesiveness of the test piece after drying (weight of the antibacterial coating formed) was calculated using the following formula.

[0073] Calculation formula: Adhesive amount (wt%) = (W T / W0- 1) × 100 where: W0: Weight of unprocessed specimen ·W T : Weight of processed test piece

[0074] The amount of sizing obtained was 0.5 wt%.

[0075] 2. Abrasion treatment test The abrasion treatment was carried out in accordance with JIS L 1076, Appendix 3 (regulations), Method J (modified Martindale method), under the following conditions. Wear fabric: Self-fabric surface Wear count: 300 times Pressing force: 4.9 N

[0076] 3.Antibacterial activity evaluation test The antibacterial activity was evaluated according to JIS L 1902:2015 (bacterial liquid absorption method) under the following conditions. Strain: Klebsiella pneumoniae (NBRC 13277) ·Culture conditions: 18 hours culture ·Inoculum concentration: 2.3 × 10 5 CFU / mL

[0077] 4. Calculation of antibacterial activity value The antibacterial activity value was calculated using the following formula.

[0078] Calculation formula: Antibacterial activity value = (log C t - log C0) - (log T t - log T0) However, when log C0 > log T0, the calculation was performed by replacing log T0 with log C0. where: C0: Number of viable bacteria in the negative control immediately after inoculation C t : Number of viable bacteria in negative control after 18 hours of incubation T0: Number of viable bacteria in the test sample immediately after inoculation T t : Number of viable bacteria in test samples after 18 hours of incubation

[0079] 5. Calculation of proliferation value The proliferation value was calculated using the following formula.

[0080] Formula: Growth value = log N t - log N0 where: N0: Number of live bacteria immediately after inoculation N t : Number of viable bacteria after 18 hours of incubation

[0081] [Table 5]

[0082] (Experimental results) In the untreated curtain specimens, the antibacterial activity decreased after the abrasion treatment, and growth of Klebsiella pneumoniae was confirmed (growth value: 0.83, antibacterial activity value: 3.17). On the other hand, the processed product coated with the antibacterial coating agent of the present invention maintained a high antibacterial effect even after abrasion treatment (antibacterial activity value: 6.25 to 6.28), and bacterial growth was strongly inhibited. This confirmed that the antibacterial coating agent of the present invention has abrasion resistance and can maintain sufficient antibacterial effect even under normal abrasion conditions in the living environment.

[0083] From the above experimental results, it was confirmed that when the antibacterial coating agent of the present invention is applied to curtains, it exhibits high antibacterial activity and can maintain its effectiveness even after 300 abrasion treatments. In particular, it has been shown to be useful as an antibacterial measure for curtains and other fabric products used in medical facilities, nursing homes, schools, and public facilities. [Industrial Applicability]

[0084] The antibacterial coating agent of the present invention is both safe and antibacterial, and therefore can be suitably used in places where microbial contamination in living areas is a concern.

Claims

1. An antibacterial coating agent used to form an antibacterial coating on a surface of an object (excluding living organisms) by applying the agent to the surface, the antibacterial coating agent comprising an aqueous film-forming agent, one or more antibacterial agents, and a stable solvent, The aqueous film-forming agent is polyvinyl alcohol, the safety of which is guaranteed. The antibacterial agent is a food additive or an extract of a food material that has been eaten, and is used in combination of one or more of them; the stable solvent is water, The antibacterial coating agent is characterized in that the antibacterial agent is a grapefruit seed extract or a peel extract selected from one or more of grapefruit, orange, and lemon.

2. 2. The antibacterial coating agent according to claim 1, wherein the polyvinyl alcohol has a degree of saponification of 98 mol % or more and a degree of polymerization of 200 to 3500.

3. 2. The antibacterial coating agent according to claim 1, wherein the non-toxic value is 1 g / kg body weight or more after repeated oral administration to rats for 28 days.

4. 2. The antibacterial coating agent according to claim 1, which can inhibit the growth of microorganisms for six months or more.

5. The antibacterial coating agent according to claim 1, characterized in that the coating formed from the antibacterial coating material loses hardness and can be peeled off by friction under conditions where it is in continuous contact with water at 40°C or higher.

Images