Antimicrobial coating composition and antimicrobial coated steel sheet using the same

Abstract

The present invention relates to an antimicrobial coating composition comprising, based on the total weight of the coating composition, 30-60% by weight of a polyester resin, 3-15% by weight of a curing agent, 0.1-5% by weight of an antimicrobial agent, 0.1-15% by weight of a pigment, and the balance being a solvent. The present invention further relates to an antimicrobial coated steel sheet comprising a steel sheet and an antimicrobial coating layer formed on at least one surface of the steel sheet, the antimicrobial coating layer containing an antimicrobial agent in at least a part thereof, the antimicrobial agent having a content ratio Z / (M+Ca) of 0.1-0.5, M being Ca, Ba, Mg, Zn, Ni, Fe or Al, and Z being P, As, V or Si. The antimicrobial coating composition according to the present invention contains an antimicrobial agent. When the composition forms a coating layer, the antimicrobial agent is concentrated on the surface of the coating layer, so that microorganisms adsorbed on the surface of the coating film together with moisture are effectively killed by hydroxyl radical species and hydroxide anions generated on the surface of the coating film. Thus, a coated steel sheet using the antimicrobial coating composition according to the present invention has excellent design properties as well as excellent processability, chemical resistance, etc.

Description

[Technical Field]

[0001] The present invention relates to an antimicrobial coating composition containing a polyester resin, a curing agent, an antimicrobial agent, a pigment, and a solvent, and an antimicrobially coated steel sheet using the same, which has excellent effects in killing bacteria, viruses, and mold, and has excellent durability and design even when used for a long period of time, and relates to an antimicrobially coated steel sheet. [Background technology]

[0002] The recent global spread of the coronavirus (COVID-19) has not only posed serious socioeconomic problems but also necessitated the urgent development of vaccines and therapeutic agents. Microorganisms that cause disease in humans and animals include Hepatitis A, C, and B viruses, HIV (AIDS), Escherichia coli, Staphylococcus aureus, Salmonella enterica, and Plasmodium falciparum, which fall under Biosafety Level 2; Mycobacterium tuberculosis, coronaviruses (SARS-1, MERS, and SARS-2), chikungunya virus, yellow fever virus, encephalitis virus, Q fever virus, Rickettsia rickettsii, Brucella, West Nile virus, and Tularemia bacillus, which fall under Biosafety Level 4; and Ebola virus, Marburg virus, Lassa virus, and smallpox, which fall under Biosafety Level 4.

[0003] The COVID-19 virus, currently spreading worldwide, is a virus containing RNA nucleic acid within a spherical envelope made of phospholipids and proteins. Most viruses penetrate human or animal host cells and multiply by replicating large amounts of nucleic acid using the host cell's ribosomes. Viruses are smaller than bacteria or fungi, allowing them to spread and replicate quickly. However, they mutate quickly, making it difficult to develop treatments or vaccines.

[0004] As part of efforts to resolve the harmful environment that presents such threats, there is a demand for the development of surface treatment products that can impart antiviral, antibacterial, and antifungal functions to the surface of steel sheets, which are essential materials in our daily lives, thereby inactivating or killing viruses, bacteria, and fungi.

[0005] Recently, it has been reported that copper metal surfaces, nanometals or metal ions, and quaternary ammonium ions have the ability to kill bacteria and some viruses. Cu metal kills microorganisms by penetrating the bacterial or viral outer membranes, causing them to lose their replication function, and metal ions such as Ag, Ni, and Zn have also been reported to kill microorganisms through a similar mechanism. Quaternary ammonium-containing polymers have been reported to kill microorganisms by their inherent hydrophobic functional groups, which bind to the bacterial or viral outer membranes and disrupt their function. However, the antimicrobial effect of these compounds is problematic because they are not completely effective when applied to the surface of a material and take a long time to develop. In particular, color steel sheets used for home appliances and building materials are typically manufactured with a coating thickness of 20 mm or more for long-term use (over 20 years). When these metals are coated on steel sheets using a liquid coating composition, the high density of the metals increases the likelihood of them remaining inside the coating, making it difficult for the coating to function on the surface.

[0006] In addition, when used for a long period of time, there is a problem of discoloration in the case of metals such as copper, whose surface color changes due to oxidation. In addition, when using quaternary ammonium, although some effects are observed, the immediate effect is insufficient and not complete, so there are limitations to its use.

[0007] Therefore, if an antimicrobial coating composition and a coated steel sheet using the same are provided, they are expected to be widely applicable in related fields. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides an antimicrobial coating composition that can kill viruses, bacteria, and fungi, and that imparts antimicrobial effects to steel sheets without significant changes in functionality even after long-term use because it uses an inorganic compound instead of a metal.The present invention also provides an antimicrobial coated steel sheet that includes an antimicrobial coating layer formed on at least one surface of the steel sheet using the antimicrobial coating composition. [Means for solving the problem]

[0009] According to one embodiment of the present invention, there is provided an antimicrobial coating composition comprising, based on the total weight of the coating composition, 30 to 60 wt % of a polyester resin; 3 to 15 wt % of a curing agent; 0.1 to 5 wt % of an antimicrobial agent; 0.1 to 15 wt % of a pigment; and the remainder being a solvent.

[0010] According to another embodiment of the present invention, there is provided an antimicrobial coated steel sheet comprising: a steel sheet; and an antimicrobial coating layer formed on at least one surface of the steel sheet, wherein at least a portion of the antimicrobial coating layer contains an antimicrobial agent, wherein the antimicrobial agent has a content ratio Z / (M+Ca) of 0.1 to 0.5, where M is Ca, Ba, Mg, Zn, Ni, Fe, or Al, and Z is P, As, V, or Si. [Effects of the Invention]

[0011] The antimicrobial coating composition according to the present invention contains an antimicrobial agent, and when the composition forms a coating layer, the antimicrobial agent is concentrated on the surface of the coating layer, so that microorganisms adsorbed to the surface of the coating along with moisture are effectively killed by hydroxyl radical species and hydroxide anions generated on the surface of the coating. Furthermore, coated steel sheets using the antimicrobial coating composition according to the present invention have excellent design properties as well as excellent processability and chemical resistance. [Brief explanation of the drawings]

[0012] [Figure 1]1 is a cross-sectional schematic diagram of an antimicrobial coated steel sheet of the present invention, showing that the antimicrobial agent and pigment are dispersed in the coating film. [Figure 2] 1 is a cross-sectional schematic view of an antimicrobial coated steel sheet of the present invention including a primer coating layer, showing that the antimicrobial agent and pigment are dispersed within the coating film. DETAILED DESCRIPTION OF THE INVENTION

[0013] While the present invention will be described in detail below with reference to preferred embodiments thereof, the scope of the present invention is not limited to the following embodiments, and the present invention may be modified in various ways.

[0014] The present invention relates to an antimicrobial coating composition that can easily kill microorganisms adsorbed on a surface and whose inorganic compound properties do not change significantly even when coated on a steel sheet and used for a long period of time, and to a coated steel sheet coated with the composition.

[0015] More specifically, the present invention provides an antimicrobial coating composition comprising, based on the total weight of the coating composition, 30 to 60 wt % of a polyester resin, 3 to 15 wt % of a curing agent, 0.1 to 5 wt % of an antimicrobial agent, 0.1 to 15 wt % of a pigment, and the balance being a solvent.

[0016] The type of polyester resin used in the antimicrobial coating composition of the present invention is not particularly limited, but it is preferable to use a urethane-modified polyester resin, which provides excellent processability and chemical resistance of the coating film when cured.

[0017] Furthermore, although not particularly limited, the weight average molecular weight (Mw) of the polyester resin may be 2,000 to 30,000, and preferably 5,000 to 25,000. If the molecular weight is less than 2,000, the chemical resistance and processability of the coating film will be insufficient, and if the molecular weight exceeds 30,000, the storage stability and workability of the solution may be impaired, which is undesirable.

[0018] Furthermore, the polyester resin of the present invention may have a hydroxyl value of 10 to 300 (units), preferably 20 to 200 (units), and an acid value of 5 to 30 mgKOH / g, preferably 10 to 25 mgKOH / g. If the hydroxyl value and acid value are outside the lower and upper limit ranges, the crosslinkability and chemical resistance of the coating film may decrease, which is undesirable.

[0019] The polyester resin may be contained in an amount of 30 to 60% by weight based on the total weight of the coating composition. If the amount is outside this range, the drying properties of the coating film may be reduced when cured, and other physical properties may also be deteriorated, which is not preferred.

[0020] In order to improve the corrosion resistance of the steel sheet to which the antimicrobial coating composition of the present invention is applied, a curing agent may be used together with the polyester resin, including, but not limited to, an aziridine-based curing agent, a melamine-based curing agent, and an isocyanate-based curing agent.

[0021] In the present invention, the aziridine-based curing agent is preferably an aziridine-based curing agent represented by the following structural formula (a).

[0022] [ka]

[0023] In the above structural formula (a), R may be -H, -CH3, -CH2CH3, -CH2CH2CH3, -CH2OH, or -CH2CH2OH, and the above aziridine-based curing agents may be used alone or in combination of two or more.

[0024] Furthermore, the melamine-based curing agent of the present invention can be iminomelamine of the following structural formula (b) or methylated melamine of the following structural formula (c).

[0025] [ka]

[0026] When using a melamine-based curing agent, iminomelamine and methylated melamine can be mixed in a weight ratio of 1:1 to 1:6, preferably 1:1 to 1:4. Iminomelamine has a fast curing reaction rate, which is advantageous for rapid curing, and as the content increases, the degree of curing increases, resulting in increased hardness of the coating film. Methylated melamine has a slower curing rate, but improves the smoothness of the coating film, providing excellent surface quality. Therefore, adding iminomelamine to methylated melamine can improve the reaction rate while also improving the surface quality of the coating film.

[0027] The iminomelamine may be, for example, dimethoxymethylmelamine, trimethoxymethylmelamine, telluramethoxymelamine, triethoxymethylmelamine, or tributoxymethylmelamine, and the methylated melamine may be butoxymethylmelamine, hexabutoxymethylmelamine, hexaethoxymethylmelamine, or hexamethoxymethylmelamine.

[0028] Furthermore, the isocyanate-based curing agent of the present invention may be an isocyanate-based curing agent such as a monoisocyanate of the following structural formula (d) or a diisocyanate of the following structural formula (e).

[0029] [ka]

[0030] In the structural formula (d), R may be methyl, ethyl, propyl, phenyl, 2-isopropylphenyl, or cyclohexyl; in the structural formula (e), R' may be 1,3-phenylene, 1,4-phenylene, tolylene-2,4, tolylene-2,6, m-xylylene, dicyclohexylmethane 4,4', methylenediphenyl 4,4', or hexamethylene; the isocyanate-based curing agents may be used alone or in combination of two or more.

[0031] The curing agent may be contained in an amount of 3 to 15 wt % based on the total weight of the coating composition. If the curing agent content is less than 3 wt %, the curing reaction of the dried coating film may not proceed well, which may result in a deterioration in the physical properties of the coating film. If the curing agent content is more than 15 wt %, the excess curing agent may result in poor processability, which is undesirable.

[0032] The antimicrobial coating composition of the present invention may contain a pigment to impart a unique color. The type of pigment that can be used in the present invention is not particularly limited, but at least one inorganic pigment selected from the group consisting of black, red, and white pigments may be used, and preferably at least one selected from the group consisting of carbon black, carbon nanotubes, graphite, graphene, ferric oxide (FeO), and titanium dioxide (TiO).

[0033] The pigment of the present invention may be contained in an amount of 0.1 to 15 wt % based on the total weight of the coating composition. If the pigment content is less than 0.1 wt %, the hiding power of the steel sheet may be insufficient, making it difficult to achieve the desired color. If the pigment content exceeds 15 wt %, the viscosity of the composition may increase, making it difficult to work with, and making it difficult to achieve a beautiful surface appearance.

[0034] Furthermore, it is preferable to use the pigment with low oil absorption, more preferably less than 60%, and most preferably 5 to 50%. If the oil absorption exceeds 60%, problems arise in that workability is poor and it is difficult to obtain the desired surface texture.

[0035] The pigment of the present invention preferably has an average particle size (particle size) within the range of ±5 μm of the thickness of the dry coating film, and for example, a particle size of 5 to 30 μm can be used. Furthermore, in addition to the above colored inorganic pigment, an anti-rust pigment can be further contained to enhance the anti-rust properties of the coating film, and the anti-rust pigment can be colloidal silica, silica sol, alkali metal silicate, or the like.

[0036] The antimicrobial coating composition of the present invention may contain an antimicrobial agent that exhibits antimicrobial properties. In the present invention, the term "microorganism" refers to a concept that includes all prokaryotic microorganisms, eukaryotic microorganisms, and non-cellular microorganisms, and means bacteria, viruses, fungi, etc.

[0037] The antimicrobial agent of the present invention is M 10 (ZO4)6X2, Ca(OH)2 or a mixture thereof, wherein M can be Ca, Ba, Mg, Zn, Ni, Fe or Al, Z can be P, As, V or Si, and X can be F, OH, Cl, O or CO3. 10 (ZO4)6X2 is Ca 10 (PO4)6(OH)2 or Mg 10 The antimicrobial agent of the present invention may be (PO4)6(OH)2, but any agent capable of generating hydroxyl radical species can be used without limitation. Ca(OH)2 can generate hydroxide anions. In one embodiment, the antimicrobial agent of the present invention is M 10 It may also be a mixture of (ZO4)6X2 and Ca(OH)2.

[0038] When a coating composition containing the antimicrobial agent forms a coating layer on a steel sheet, microorganisms adsorbed to the surface of the coating layer are effectively killed by hydroxyl radical species and hydroxide anions generated in the coating layer. Furthermore, the moisture contained in the microorganisms allows them to easily adsorb to the surface of the coating layer, which generates hydroxyl radical species and hydroxide anions, making them more easily killed.

[0039] The antimicrobial agent is M 10 (ZO4)6X2 and Ca(OH)2 may be mixed in a weight ratio of 5:1 to 1:5, preferably 3:1 to 1:3. The most effective antimicrobial properties can be obtained within the above range.

[0040] In particular, the antimicrobial agent of the present invention is an inorganic compound and has a relatively low density compared to metal particles. When a coating layer is formed, the antimicrobial agent easily rises to the surface of the coating layer and is mainly concentrated on the surface of the coating layer when it dries, thereby easily killing microorganisms adsorbed to the surface.

[0041] The antimicrobial coating composition of the present invention can be prepared by dispersing a curing agent in a polyester resin, which is a base resin, to prepare a resin composition, and then adding and dispersing a pigment and an antimicrobial agent, followed by adding the resulting dispersion to a solvent.

[0042] The solvent may be at least one selected from the group consisting of toluene, xylene, isopropanol, solvent naphtha, cellosolve, cellosolve acetate, and butyl cellosolve, and may be used alone or in combination of two or more.

[0043] The solvent is the remainder other than the polyester resin, curing agent, antimicrobial agent, and pigment, and the viscosity of the coating composition may vary depending on the content of the solvent, but the content of the solvent added to the composition may be adjusted as needed. For example, the content may be adjusted to maintain a viscosity that requires 20 to 200 seconds for the coating composition to be discharged from a DIN cup (DIN, 53211), taking into consideration the coating amount and adhesion of the coating composition.

[0044] In order to further improve the physical properties of the coating film, the coating composition of the present invention may further contain additives such as wax, curing catalyst, pigment anti-aggregation agent, defoaming agent, leveling agent, etc. If the additives are generally used in the art, they can be appropriately used in the present invention and can be applied to the coating composition of the present invention according to the usual method of use.

[0045] Furthermore, when a coating film is formed using the coating composition of the present invention, the components of the coating composition form a composite network structure, which provides excellent press workability and surface functionality.

[0046] Another embodiment of the present invention provides an antimicrobial coated steel sheet comprising an antimicrobial coating layer formed on at least one of both surfaces of the steel sheet using the antimicrobial coating composition of the present invention, wherein an antimicrobial agent may be dispersed within the antimicrobial coating layer.

[0047] Specifically, the present invention provides an antimicrobial coated steel sheet comprising a steel sheet and an antimicrobial coating layer formed on at least one surface of the steel sheet, wherein at least a portion of the antimicrobial coating layer contains an antimicrobial agent, wherein the content ratio of the antimicrobial agent, Z / (M+Ca), is 0.1 to 0.5, where M is Ca, Ba, Mg, Zn, Ni, Fe, or Al, and Z is P, As, V, or Si.

[0048] In the antimicrobial coated steel sheet of the present invention, the steel sheet may be a plated steel sheet. Specifically, the plated steel sheet may be a galvanized steel sheet, such as a hot-dip galvanized steel sheet (GI), a galvannealed hot-dip galvanized steel sheet (GA), an electrogalvanized steel sheet (EG), an aluminum-plated steel sheet, or a zinc-aluminum-magnesium ternary alloy-plated steel sheet.

[0049] Furthermore, the antimicrobial coating layer may be formed from an antimicrobial coating composition containing, based on the total weight of the coating composition, 30 to 60% by weight of polyester resin, 3 to 15% by weight of curing agent, 0.1 to 5% by weight of antimicrobial agent, 3.0 to 15% by weight of pigment, and the remainder being solvent.

[0050] When a coating film is formed using the antimicrobial coating composition of the present invention, the coating film may have a dry thickness of 3 to 40 μm, preferably 5 to 30 μm. The coating composition can have a variety of colors by containing a pigment, but if the dry thickness is less than 5 μm, the coating film may have poor color development, hiding power, processability, and solvent resistance. If the dry thickness is more than 30 μm, the production cost increases and productivity decreases, which is undesirable.

[0051] In another embodiment of the present invention, when an antimicrobial coating layer is formed on only one side of a plated steel sheet, it is preferable to form a coating layer on the other side of the plated steel sheet on which the antimicrobial coating layer is not formed, taking into consideration the workability and corrosion resistance of the steel sheet.

[0052] According to one embodiment of the present invention, a primer coating layer is formed on both sides of a plated steel sheet, and the antimicrobial coating layer of the present invention is formed on at least one side of the primer coating layer. That is, as shown in Figure 2, the primer coating layer can be located between the plated steel sheet and the antimicrobial coating layer.

[0053] The primer coating layer is intended to improve the paint adhesion between the surface of the steel sheet and the antimicrobial coating layer, as well as the hardness, chemical resistance, corrosion resistance, etc. of the coating film, and can be selected from commercially available compositions for forming an undercoat layer depending on the application of the steel sheet and the type of steel sheet or resin. For example, an epoxy polyester paint, an epoxy-modified polyester paint, a polyester paint for PCM, or a polyester undercoat paint for modified PMC can be used.

[0054] To enhance the rust prevention properties of the primer coating layer and ensure corrosion resistance, the primer coating may further contain a conventional chromium-based or chromium-free rust-preventive pigment. Examples of the chromium-based rust-preventive pigment include zinc potassium chromate, zinc tetraoxychromate, and strontium chromate. Examples of the chromium-free rust-preventive pigment include barium metaborate, zinc molybdate, calcium zinc molybdate, zinc phosphate, aluminum triphosphate, calcium borosilicate, and phosphosilicate.

[0055] The thickness of the dry coating film of the primer coating layer is not particularly limited, but if it is less than 3 μm, rust prevention and adhesion may be reduced, and if it exceeds 7 μm, the surface appearance may be poor and economic efficiency may be reduced. Therefore, the thickness of the dry coating film is preferably 3 to 7 μm, and more preferably 4 to 6 μm.

[0056] The primer coating layer may be formed by roll coating or curtain flow, which is used for PCM steel sheets. The baking conditions after coating are preferably such that the peak metal temperature (PMT) is 180 to 220°C in a PCM continuous line.

[0057] When a primer coating layer is further included, the primer coating layer may be formed to a thickness of 1 to 10 μm.

[0058] By further including a primer coating layer, the anti-corrosion effect and hiding power of the plated steel sheet can be increased, and diffused reflection of light can be reduced, resulting in better color development.

[0059] Furthermore, the antimicrobial coated steel sheet of the present invention may include a coating film additionally formed on at least one surface of the steel sheet, which increases the adhesion between the steel sheet and the antimicrobial coating layer and can impart to the plated steel sheet properties generally required for other steel sheets, such as paintability and corrosion resistance. Therefore, any coating film that can be applied between a base steel sheet and a topcoat coating in the art may be included without limitation.

[0060] The present invention will be described in more detail with reference to the following specific examples. The following examples are merely illustrative examples to aid in understanding the present invention, and are not intended to limit the scope of the present invention. [Example]

[0061] Example 1. Preparation of antimicrobial coating composition Antimicrobial coating compositions containing urethane-modified polyester, curing agent, pigment, and antimicrobial agent in the amounts shown in Table 1 below were prepared.

[0062] The urethane-modified polyester resin used was a resin with a weight-average molecular weight of 16,000 to 20,000 (KCC Corporation, Tg = 10-30°C), and the aziridine-based curing agent was trimethylolpropane tris(β-N-aziridinyl)propionate, the melamine-based curing agent was methoxymethylmelamine, and the isocyanate-based curing agent was toluene diisocyanate. Carbon black (Ebonix, Printex) was used as the black pigment. TM ), ferric oxide (Fe2O3) as the red pigment, and titanium dioxide (TiO2) as the white pigment. Hydroxyapatite (Ca) was used as the antimicrobial agent. 10 Hydroxyapatite (PO4)6(OH)2) (KR BIOTECH Ltd.), calcium hydroxide (Ca(OH)2), or a mixture of the above hydroxyapatite and calcium hydroxide in a weight ratio of 1:3 to 3:1 was used.

[0063] [Table 1]

[0064] 2. Production of antimicrobial coated steel sheets and evaluation of their physical properties The antimicrobial coating composition prepared in 1 above was used to coat the surface of the plated film with a coating weight of 60 g / m 2 Antimicrobial coated steel sheets were produced by roll coating a Zn-Al-Mg ternary alloy-plated steel sheet to a dry thickness of 15-20 μm, curing and drying at a peak metal temperature (PMT) of 232°C, and then cooling. When a primer coating layer was present, it was adjusted to a thickness of 5 μm. The coating thickness was measured using a non-destructive portable coating thickness gauge.

[0065] (1) Appearance evaluation The paint film color design and the uniformity and continuity of the texture were evaluated relatively and expressed as follows:

[0066] [Evaluation criteria] ◎: (very good), ○: (good), △: (poor), X: (very poor)

[0067] (2) Gloss evaluation The 60° specular reflectance was measured and evaluated using equipment from SHEEN.

[0068] (3) Pencil hardness evaluation A 10cm line was drawn at a 45° angle with a Mitsubishi pencil (HB-4H) under a load of 1000±10g, and the surface was evaluated based on whether scratches occurred.

[0069] (4) Corrosion resistance evaluation The corrosion resistance was evaluated using the Cyclic Corrosion Test (CCT). The specimens were exposed to a salt spray (5% concentration, 1 kg / cm at 35°C) for 5 hours under conditions of 95% relative humidity. 2 The steel sheets were then dried at a relative humidity of 30% and a temperature of 70°C for two hours, and then treated at a relative humidity of 95% and a temperature of 50°C for three hours. This cycle was repeated 100 times, and the area of ​​white rust that appeared on the surface of the steel sheets was evaluated.

[0070] [Evaluation criteria] ◎: Corrosion area is 0%, ○: Corrosion area is more than 0% but less than 5%, △: Corrosion area is more than 5% but less than 30%, X: Corrosion area is more than 30%

[0071] (5) Processability evaluation The antimicrobial coated steel plate was placed in a vice, bent 180° with a pressure of 1 kgf, and then clamped until it was flat (0T bending). Scotch tape was applied to the bent coating, and the coating layer was peeled off to evaluate whether cracks occurred or not.

[0072] [Evaluation criteria] ◎: No cracks or peeling, ○: Fine cracks observed but no peeling of the coating, △: Severe cracks but no peeling of the coating, X: Cracks and peeling of the coating

[0073] (6) Chemical resistance evaluation The surface was evaluated by rubbing back and forth with gauze moistened with MEK (Methyl Ethyl Ketone) at 1 kgf and counting the number of times it was rubbed until the coating film peeled off.

[0074] [Evaluation criteria] ◎: 100 times or more, ○: 70 times or more but less than 100 times, △: 40 times or more but less than 70 times, X: Less than 40 times

[0075] (7) Antiviral evaluation The virus was evaluated by KR BIOTECH Ltd. in accordance with ISO 21702. COVID-19 (2.15 × 10 7 400 mL of the virus stock solution (TCID50 / mL) was dropped onto each of the control group and composite resin-coated steel plate test pieces (50 x 50 mm), and covered with Cover Glass. After incubation at room temperature for a certain period of time, the virus was recovered by washing with 10 mL of SCDLP medium. The virus solution was then diluted with SCDLP liquid for 10 minutes. -1 ~10 -5 Sample solutions (two sets of five wells) were prepared by serial dilution until the virus reached a concentration of 0.01%. Each smear was then used to infect monkey host cells (Vero E6 cells) and cultured at 37°C for 24 hours. MTT staining solution (Triazolium) was dropped into each culture well, and the color change was observed to determine whether the host cells were viable. The concentration of viable cells (TCID50) in each well was calculated using a statistical method (Spearman-Karber method), and the virus mortality rate was quantitatively evaluated by comparing it with the control group of uncoated galvanized steel sheets.

[0076] [Evaluation criteria] Virus kill rate: ◎: 99.0% or more, ○: 90% to less than 99.0%, △: 80% to less than 90%, X: Less than 80%

[0077] (8) Antibacterial evaluation Antibacterial evaluation was performed at the Korea Institute of Construction, Living Environment and Lifestyle in accordance with JIS Z 2801:2012 standard for four types of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Pneumococcus). The control group and composite resin-coated steel plates (50 × 50 mm) were placed in plastic petri dishes and inoculated with NB (nutrient) medium at a concentration of 2.5 × 10 5 ~10 6 CFU / ml) were cultured, and 400 μL of bacterial solution was dropped onto the specimen. The specimen was covered with a Stomacher film (40 × 40 mm) to bring the bacterial solution into close contact with the specimen, and the test was performed with a constant contact area. The inoculated specimen was then exposed to the temperature (35 ± 0.1 °C) and relative humidity (92.9 ± 0.5%) for 24 hours, after which it was washed with 10 mL of SCDLP medium to recover the bacteria, which were then serially diluted to 10 -1 ~10 -5 The sample solution was prepared until the concentration reached 1 mL. 1 mL of the sample solution was dispensed into a petri dish, and 1.5% agar medium was added and mixed. The inverted petri dish was placed in an incubator at 37°C and the bacteria were cultured for 24 hours. The number of colonies was then counted and the viable bacterial count (CFU / 0.1 mL, Log10) (CFU: colony-forming units) was calculated. The bacterial mortality rate was quantitatively evaluated by comparing it with a control group of uncoated galvanized steel sheets.

[0078] [Evaluation criteria] Bacterial death rate: ◎: 99.0% or more, ○: 90% to less than 99.0%, △: 80% to less than 90%, X: Less than 80%

[0079] (9) Antifungal evaluation The test was conducted at the Korea Construction and Living Environment Testing Institute (KCL) in accordance with the standard test method (KCL FIR-1003:2011) for five types of mold (Aspergillus niger, Penicillium pinophilum, Chaetomium globosum, Gliocladium virens, Aureobasidium pullulans). The above mold strains were inoculated onto the surface of a steel plate (50 x 50 mm), and the area of ​​mold mycelium growth was evaluated after four weeks to assess antifungal properties.

[0080] [Evaluation criteria] The area of ​​the inoculated test piece where mycelia grew was: ◎: Less than 3% of the total area; ○: 3% to less than 10% of the total area; △: 10% to less than 20% of the total area; X: 20% or more of the total area

[0081] The results of the above evaluation are shown in Table 2 below.

[0082] [Table 2]

[0083] As shown in Examples 31 to 34 in Table 2, when the antimicrobial agents were used as a mixture, they exhibited superior antiviral, antibacterial, and antifungal properties. That is, Examples 17 to 30 in Table 2 correspond to experimental examples employing one of Examples 1 to 12, in which two or more antibiotic compounds were used as a mixture, and exhibited superior antiviral, antibacterial, and antifungal properties compared to Examples 31 to 34, which correspond to experimental examples employing one of Examples 13 to 16, in which only one of the components of the antibiotic compound (hydroxyapatite and calcium hydroxide) was used, and Comparative Examples 4 to 6, which correspond to comparative experimental examples employing one of Comparative Examples 1 to 3, in which no antibiotic compound was used.

Claims

1. 30 to 60 wt % of polyester resin; 3 to 15 wt % of curing agent; 0.1 to 5 wt % of antimicrobial agent; 3.0 to 15 wt % of pigment; and the balance being solvent, based on the total weight of the coating composition. The antimicrobial agent has a weight ratio of Z / (M+Ca) of 0.1 to 0.5, wherein M is Ca, Ba, Mg, Zn, Ni, Fe, or Al, and Z is P, As, V, or Si.

2. The antimicrobial coating composition according to claim 1 , wherein the polyester resin is a urethane-modified polyester resin.

3. The antimicrobial coating composition according to claim 1 , wherein the curing agent is an aziridine-based curing agent, a melamine-based curing agent, or an isocyanate-based curing agent.

4. The antimicrobial agent is M １０ (ZO ４ ) ６ X ２ and Ca(OH) ２ wherein M is Ca, Ba, Mg, Zn, Ni, Fe, or Al, Z is P, As, V, or Si, and X is F, OH, Cl, O, or CO. ３ 2. The antimicrobial coating composition of claim 1, wherein

5. The antimicrobial agent is Ca １０ (P.O. ４ ) ６ (OH) ２ and Ca(OH) ２ 5. The antimicrobial coating composition according to claim 4, wherein the above are mixed in a weight ratio of 3:1 to 1:

3.

6. The pigments include carbon black, carbon nanotubes, graphite, graphene, ferric oxide (Fe ２ O ３ ) and titanium dioxide (TiO ２ 2. The antimicrobial coating composition of claim 1, wherein the antimicrobial coating composition is at least one selected from the group consisting of:

7. 2. The antimicrobial coating composition according to claim 1, wherein the pigment has a particle size of 0.01 to 20 μm and an oil absorption of 5 to 60%.

8. The antimicrobial coating composition of claim 1, wherein the composition has a peak metal temperature (PMT) of 180 to 260°C.

9. 2. The antimicrobial coating composition of claim 1, wherein the solvent is at least one selected from the group consisting of toluene, xylene, isopropanol, solvent naphtha, cellosolve, cellosolve acetate, and butyl cellosolve.

10. An antimicrobial coated steel sheet comprising: a steel sheet; and an antimicrobial coating layer formed on at least one surface of the steel sheet, wherein at least a portion of the antimicrobial coating layer contains an antimicrobial agent, the antimicrobial agent being a mixture of M 10 (ZO 4 ) 6 X 2 and Ca(OH) 2 in a weight ratio of 3:1 to 1:3, wherein M is Ca, Ba, Mg, Zn, Ni, Fe, or Al, Z is P, As, V, or Si, and X is F, OH, Cl, O, or CO 3 .

11. The antimicrobial coated steel sheet according to claim 10, wherein the steel sheet is a plated steel sheet.

12. The antimicrobial coated steel sheet according to claim 11, wherein the plated steel sheet is a hot-dip galvanized steel sheet (GI), a galvannealed hot-dip galvannealed steel sheet (GA), an electrogalvanized steel sheet (EG), an aluminum-plated steel sheet, or a zinc-aluminum-magnesium (Zn-Al-Mg) ternary alloy-plated steel sheet.

13. The antimicrobial coated steel sheet according to claim 10, wherein the antimicrobial coating layer has a thickness of 3 to 40 μm after drying.

14. The antimicrobial coated steel sheet according to claim 10, further comprising a primer coating layer provided between the steel sheet and the antimicrobial coating layer.

15. An antimicrobial coated steel sheet comprising: a steel sheet; and an antimicrobial coating layer formed on at least one surface of the steel sheet, wherein the antimicrobial coating layer is formed from the antimicrobial coating composition according to any one of claims 1 to 9.

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