Antibacterial and self-cleaning composite coating film

Abstract

The present invention relates to a composite coating film, which has transparency, a self-cleaning function, antibacterial properties, and excellent moisture and oxygen barrier properties. The film comprises: a film substrate; and at least two barrier layers consisting of cellulose-based nanofibers and chitin-based nanofibers substituted with guanidine, which are stacked layer by layer on the film substrate. In addition, the film comprises, on the other side thereof, a self-cleaning porous nano-coating layer in which chitin-based nanofibers substituted with guanidine and inorganic particle layers are alternately stacked layer by layer in two or more layers, wherein the coating layer also comprises an essential oil. The composite coating film provides excellent transparency, oxygen and moisture permeability, and antibacterial effects.

Description

Antibacterial and self-cleaning composite coating film

[0001] The present invention relates to a composite coating film having antibacterial properties, being self-cleaning, being transparent, and having excellent moisture and oxygen blocking properties.

[0002] Products such as meat, agricultural products, and cheese do not require any additional additives, so the performance of packaging materials during distribution, storage, and preservation plays a significant role in maintaining product freshness.

[0003] The materials mainly used for packaging the above products are polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), which are widely used because they are optically transparent and can protect the product from mechanical impact.

[0004] However, the above packaging material has high oxygen and moisture permeability, making it vulnerable to fat rancidity and oxidation of the food inside, and has the disadvantage of reduced safety against aerobic microorganisms and reduced marketability and storability due to hydration / dehydration.

[0005] To reduce oxygen and moisture permeability, existing films are coated with aluminum or chlorinated polymers such as polyvinylidene chloride (PVDC), but this can make the material opaque or cause environmental problems.

[0006] Additionally, for meat and agricultural products, fogging inside the packaging may occur due to temperature changes during storage and distribution, which can create an environment conducive to staining or growth of microorganisms on the product, so caution is required.

[0007] Therefore, there is a need to develop a food packaging coating film that has excellent transparency, oxygen and moisture barrier properties, self-cleaning ability, and antibacterial effects.

[0008] The present invention aims to provide a composite coating film that prevents spoilage and rancidity of food due to oxygen and moisture permeability, self-cleans contaminants, and has an antibacterial effect against microorganisms.

[0009] The present invention aims to provide a composite coating film that has excellent transparency and can maintain some antibacterial effect even when some oil is lost.

[0010] The present invention provides a composite coating film comprising: a substrate; a barrier layer in which cellulose-based nanofiber layers and chitin-based nanofiber layers substituted with guanidine groups are alternately laminated on one surface of the substrate; and a self-cleaning layer in which guanidine-based chitin-based nanofiber layers substituted with guanidine groups and inorganic particle layers are alternately laminated on the other surface of the substrate; wherein the self-cleaning layer includes essential oil.

[0011] According to one aspect of the present invention, the substrate may include a barrier layer in which two or more layers of cellulose-based nanofiber layers and chitin-based nanofiber layers substituted with guanidine groups are alternately laminated on one surface of the substrate, and a self-cleaning layer in which two or more layers of chitin-based nanofiber layers substituted with guanidine groups and inorganic particle layers are alternately laminated on the other surface of the substrate.

[0012] According to one aspect of the present invention, the chitin-based nanofiber surface-modified with guanidine may have a guanidine content per unit weight of 0.2 to 2 mmol / g.

[0013] According to one aspect of the present invention, the essential oil may include one or two or more selected from eugenol, isoeugenol, castor oil, eugenol acetate, carvacrol, linalool, thymol, geraniol, geranylacetate, bicyclogermacrene, cinnamaldehyde, geranial, neral, 1,8-cineole, methyl chavicol, methyl cinnamate, methyl eugenol, camphor, α-thujone, viridiflorol, limonene, (Z)-linalool oxide, α-pinene, p-cymene, (E)-caryophyllene, and γ-terpinene.

[0014] According to one aspect of the present invention, the essential oil may be a mixture of eugenol and castor oil in a ratio of 1:9 to 9:1.

[0015] According to one aspect of the present invention, the thickness of the barrier layer may be 0.1 to 100 μm.

[0016] According to one aspect of the present invention, the composite coating film may have a transmittance of 60 to 95% measured at a wavelength of 550 nm according to JIS-K-7105.

[0017] According to one aspect of the present invention, the composite coating film has an oxygen permeability of 1 ml / m according to ASTM D3985. 2 / day may be less than.

[0018] According to one aspect of the present invention, the composite coating film has a moisture permeability of 10 g / m according to ASTM E96. 2 / day may be less than that.

[0019] According to one aspect of the present invention, the composite coating film 1 cm 2 The sliding angle of the water droplet after attaching scotch tape to the size, placing a 100 g weight on it, and removing it after 1 hour may be less than 5 degrees.

[0020] (The above 'slip angle' refers to the angle of inclination at which liquid begins to flow based on a horizontal floor surface.)

[0021] According to one aspect of the present invention, when the disk diffusion method is applied to the composite coating film, the sterilization diameter may be 0.5 cm or more.

[0022] According to one aspect of the present invention, a self-cleaning food packaging material manufactured from the composite coating film can be provided.

[0023] According to one aspect of the present invention, a method for manufacturing a composite coating film can be provided, comprising: a) a step of sequentially and alternately laminating a first dispersion containing chitin-based nanofibers substituted with a guanidine group and a second dispersion containing cellulose nanofibers on one surface of a film substrate to manufacture a barrier layer; b) a step of sequentially and alternately laminating a first dispersion containing chitin-based nanofibers substituted with a guanidine group and a third dispersion containing silica particles on the other surface of the film substrate to manufacture a self-cleaning porous nano-coating layer; and c) a step of impregnating the self-cleaning porous nano-coating layer with an essential oil.

[0024] According to one aspect of the present invention, after step a), a step of performing UV ozone treatment on the other side of the film substrate may be further included.

[0025] The self-cleaning composite coating film of the present invention blocks oxygen and moisture, is easy to self-clean, and also has excellent antibacterial function, making it suitable for use as a functional food packaging material capable of packaging fish or meat, which are vulnerable to microorganisms.

[0026] Figure 1 is a schematic diagram of a composite coating film.

[0027] Figure 2 is a graph regarding an antibacterial test using a shaking culture method for composite coating films of examples and comparative examples.

[0028] The present invention will be described in more detail below through specific examples or embodiments, including the attached drawings. However, the following specific examples or embodiments are merely references for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

[0029] Additionally, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0030] Additionally, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

[0031] Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0032] Essential oil refers to aromatic compounds extracted from various parts of plants or herbs, such as leaves, stems, fruits, flowers, roots, bark, and seeds.

[0033] The present invention provides a composite coating film comprising: a substrate; a barrier layer in which cellulose-based nanofiber layers and chitin-based nanofiber layers substituted with guanidine groups are alternately laminated on one surface of the substrate; and a self-cleaning layer in which guanidine-based chitin-based nanofiber layers substituted with guanidine groups and inorganic particle layers are alternately laminated on the other surface of the substrate; wherein the self-cleaning layer includes essential oil.

[0034] According to one aspect of the present invention, the substrate may include a barrier layer in which two or more layers of cellulose-based nanofiber layers and chitin-based nanofiber layers substituted with guanidine groups are alternately laminated on one surface of the substrate, and a self-cleaning layer in which two or more layers of chitin-based nanofiber layers substituted with guanidine groups and inorganic particle layers are alternately laminated on the other surface of the substrate.

[0035] The composite coating film of the present invention provides a composite coating film including a barrier layer in which a chitin-based nanofiber layer substituted with a guanidine group is mixed with a chitin-based nanofiber layer, and a self-cleaning layer in which a chitin-based nanofiber layer substituted with a guanine group is mixed with an inorganic particle layer, thereby providing high transparency and low oxygen permeability and moisture permeability, thereby allowing food to remain fresh for a long time, and in particular, has an excellent antibacterial effect, thereby having the advantage of being able to suppress food spoilage caused by microorganisms even when stored for a long period of time.

[0036] Specifically, the chitin nanofibers substituted with guanine groups included in the chitin nanofiber layer substituted with guanine groups refer to chitin nanofibers whose surface has been modified with guanidinium ions.

[0037] The above guanidinium ion includes one represented by the following chemical formula 1.

[0038] [Chemical Formula 1]

[0039]

[0040] In the above chemical formula 1, R may be a direct bond, a straight-chain or branched aliphatic group having 1 to 10 carbon atoms, or a cyclic aliphatic group or aromatic group having 3 to 10 carbon atoms, preferably a direct bond, or a straight-chain or branched aliphatic group having 1 to 10 carbon atoms, more preferably a direct bond, or a straight-chain or branched aliphatic group having 1 to 5 carbon atoms.

[0041] The above guanidinium ion, in the form of a cation, forms an ionic bond with anions on the hydrogel surface or in living tissues, and can provide excellent physical adhesion by forming hydrogen bonds with hydroxyl or amine groups contained in living tissues or hydrogels. Furthermore, the introduction of guanidinium ions into chitin-based nanofibers enhances the intracellular permeability of the nanofibers, further enhancing their biocompatibility.

[0042] At this time, the substituent containing the guanidinium ion may be included in an amount of 0.2 to 2 mmol / g based on the dry weight of chitin or chitosan nanofibers, preferably in an amount of 0.4 to 1.2 mmol / g, and more preferably in an amount of 0.5 to 1 mmol / g, but is not limited thereto.

[0043] Now, each layer of the composite coating film will be described in detail.

[0044] The above substrate may be a film substrate, and may include a single sheet, laminated sheet, or co-extruded product such as an acrylic film, a polyolefin film, a polyamide film, a polyurethane film, or a polyester film. For example, it may be preferable to use a polyester film, but the present invention is not limited thereto. Examples of the polyester film include, but are not limited to, one or more selected from the group consisting of a polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, and a polybutylene terephthalate (PBT) film.

[0045]

[0046] [Barrier layer]

[0047] According to one aspect of the present invention, the barrier layer may be a multilayer thin film laminate (layer by layer assembly) in which two or more layers of cellulose-based nanofiber layers and chitin-based nanofiber layers substituted with guanidine groups are alternately laminated to further improve oxygen and moisture penetration while simultaneously improving transparency.

[0048] The method for laminating the cellulose-based nanofiber layer and the chitin-based nanofiber layer substituted with guanidine groups is not limited, but a multilayer thin film lamination method can be preferably used.

[0049] The above multilayer thin film lamination method may use a dip coating method, a spray method, a casting method, etc., and the spray method may be preferably used, but is not limited thereto.

[0050] Multilayer thin film deposition allows for the formation of complex structures in a regular and stable manner, as the compounds constituting each layer are connected by strong bonds such as electrostatic interaction, hydrogen bonding, or covalent bonding. It is also possible to control the film thickness, surface roughness, and porosity at the nanoscale.

[0051] Since the above barrier layer is manufactured using the multilayer thin film lamination method, it has the advantage of excellent transparency while also having an excellent functional effect of preventing the penetration of oxygen and moisture.

[0052] In addition, since the multilayer structure of the barrier layer is composed of a cellulose nanofiber layer and chitin nanofibers substituted with guanidine groups, it has the advantage of suppressing the formation of fog, controlling the diffusion path of penetrating oxygen and moisture, and providing excellent transparency, and in particular, having an excellent antibacterial effect that inhibits the growth of bacteria and microorganisms.

[0053] A cellulose-based nanofiber layer may be first applied on top of the above film substrate, and a chitin-based nanofiber layer may also be first deposited, but is not limited thereto.

[0054] In addition, the number of layers is not limited, but the cellulose-based nanofiber layer and the chitin-based nanofiber layer substituted with a guanidine group can be laminated in 10 or more layers each, preferably in 10 to 100 layers, and more preferably in 20 to 60 layers.

[0055] The thickness of the barrier layer according to one aspect of the present invention may be 1 to 100 μm, preferably 3 to 50 μm, and more preferably 5 to 10 μm, but is not limited thereto.

[0056] According to one aspect of the present invention, the barrier layer can block oxygen and moisture more effectively by replacing the surfaces of cellulose-based nanofibers and chitin-based nanofibers substituted with guanidine groups with different charges, thereby further increasing the bonding strength of each layer, resulting in excellent durability.

[0057] According to one aspect of the present invention, by substituting a portion of the surface of the cellulose-based nanofiber with an anionic charge, the binding force with the chitin-based nanofiber substituted with a guanidine group can be improved.

[0058] The method for substituting the negatively charged surface of the above cellulose nanofibers is not limited, but preferably, hydrochloric acid, sulfuric acid, nitric acid, etc. can be used, but is not limited thereto.

[0059] The film substrate having the above barrier layer deposited on one side is effective in blocking oxygen and moisture, but by depositing a self-cleaning layer on the other side of the film substrate, a composite coating film layer capable of self-cleaning and having an even better oxygen and moisture blocking effect can be provided.

[0060]

[0061] [Self-cleaning layer]

[0062] According to one aspect of the present invention, the self-cleaning porous nano-coating layer may be formed by alternately stacking two or more layers of chitin-based nanofiber layers substituted with guanidine groups and inorganic particle layers.

[0063] The structure of the above self-cleaning layer is manufactured using a multilayer thin film lamination method in the same manner as the structure of the above barrier layer.

[0064] The above self-cleaning layer is manufactured by a multilayer thin film coating method using a chitin nanofiber layer substituted with a guanidine group and an inorganic particle layer, so that the oxygen and moisture blocking rate increases and it can be manufactured as a composite coating film capable of self-cleaning from external foreign substances.

[0065] A chitin-based nanofiber layer substituted with a guanidine group may be deposited first on the upper portion of the above film substrate, and inorganic particles may also be deposited first, but are not limited thereto.

[0066] In addition, the number of layers is not limited, but the chitin-based nanofiber layer substituted with a guanidine group and the inorganic particle layer can be laminated in two or more layers each, preferably in 2 to 10 layers, and more preferably in 3 to 5 layers.

[0067] In addition, according to one aspect of the present invention, the thickness of the self-cleaning layer may be 0.1 to 20 μm, preferably 0.5 to 15 μm, and more preferably 5 to 15 μm, but is not limited thereto.

[0068] As the barrier layer and self-cleaning layer satisfy the above-described number of layers and thickness, the composite coating film has the advantage of excellent transparency and increased oxygen and moisture blocking effects. In addition, self-cleaning is possible, effectively preventing water or foreign substances from adhering to the surface of the composite coating film.

[0069] The types of the above inorganic particles may include inorganic oxide particles, metal hydroxides, oxides, and metal oxide particles, and are preferably inorganic oxide particles, but are not limited thereto.

[0070] The above inorganic oxide particles may be mixed particles of one or more selected from silica particles, alumina particles, titanium dioxide particles, magnesium oxide particles, etc., and are preferably silica particles, but are not limited thereto.

[0071] In particular, since the silica particles have a negative surface charge, they have the advantage of excellent bonding strength between each layer when laminated as a multilayer thin film with the chitin-based nanofiber layer substituted with guanidine groups, which are overall cationic charges.

[0072] In addition, the size of the above-mentioned inorganic particles may be nano-sized, specifically 1 to 100 nm, preferably 10 to 80 nm, and more preferably 20 to 50 nm, but is not limited thereto.

[0073] When the particle size is as above, the transparency is excellent during lamination, and due to the large surface area, it has the advantage of excellent binding strength with chitin-based nanofibers substituted with guanidine groups.

[0074] According to one aspect of the present invention, the silica particles may be surface-treated with a hydrophobic silane compound.

[0075] The hydrophobic silane compound may include at least one or two or more selected from the group consisting of, but not limited to, octyltrichlorosilane, octyltrimethoxysilane, decyltrimethoxysilane, decylmethyldichlorosilane, dodecylchlorosilane, dodecyltrichlorosilane, dodecyltrimethoxysilane, tetradecyltriethoxysilane, tetradecyltrichlorosilane, tetradecyltrimethoxysilane, and the like, but is not limited thereto.

[0076] By surface-treating the silica particles with the hydrophobic silane compound, the surface of the silica particles is replaced with hydrophobicity, so that not only is self-cleaning improved, but the bonding strength with the chitin-based nanofiber layer is further increased, so that there is an advantage of increased oxygen and moisture blocking efficiency.

[0077] Moreover, since the composite coating film includes the barrier layer on one side and the self-cleaning layer on the other side, the degree of oxygen and moisture penetration is almost at a sealing level of 3 g / m. 2 / day or less, it can have a remarkable effect of reducing the level, so when used as food packaging, it can more effectively prevent rancidity or spoilage of food.

[0078] According to one aspect of the present invention, the self-cleaning layer may include essential oil.

[0079] By including the essential oil inside and on the surface of the self-cleaning layer, the efficiency of preventing oxygen and moisture penetration is further increased, and in particular, there is an advantage in that liquids such as water do not bind to the self-cleaning layer, so that the self-cleaning effect can be further increased.

[0080] In addition, since the essential oil is contained between the chitin-based nanofiber layer and the nanoparticle layer substituted with the guanidine group, the interaction between the components can inhibit the growth of bacteria and microorganisms, and the volatility of the essential oil can be reduced, thereby maintaining the antibacterial effect for a long period of time.

[0081] According to one aspect of the present invention, the essential oil may include one or two or more selected from eugenol, isoeugenol, castor oil, eugenol acetate, carvacrol, linalool, thymol, geraniol, geranylacetate, bicyclogermacrene, cinnamaldehyde, geranial, neral, 1,8-cineole, methyl chavicol, methyl cinnamate, methyl eugenol, camphor, α-thujone, viridiflorol, limonene, (Z)-linalool oxide, α-pinene, p-cymene, (E)-caryophyllene, and γ-terpinene.

[0082] According to one aspect of the present invention, the essential oil may be a mixture of eugenol and castor oil in a ratio of 1:9 to 9:1, specifically, 3:7 to 7:3, but is not limited thereto.

[0083] According to one aspect of the present invention, the composite coating film may have a transmittance measured at a wavelength of 550 nm of 60 to 95%, preferably 65 to 90%, and more preferably 70 to 85%, but is not limited thereto, according to JIS-K-7105.

[0084] When manufacturing food packaging using the above composite coating film, it is easy to visually check the condition of food inside the packaging by satisfying the above transmittance.

[0085] As the thickness of the above barrier layer and the above self-cleaning layer satisfies the above range, there is an advantage of being able to effectively prevent the penetration of oxygen and moisture while having excellent transparency.

[0086] According to one aspect of the present invention, the composite coating film has an oxygen permeability of 1 ml / m according to ASTM D3985. 2 / day or less, preferably 0.5 ml / m 2 / day or less, more preferably 0.001 to 0.1 ml / m 2 / day may be, but is not limited to,

[0087] According to one aspect of the present invention, the composite coating film has a moisture permeability of 10 g / m according to ASTM E90. 2 / day or less, preferably 5.0 g / m 2 / day or less, more preferably 2 to 3 g / m 2 / day may be, but is not limited to,

[0088] Since the composite coating film satisfies the moisture permeability and oxygen permeability within the above range, when the composite coating film is used as a food packaging material, the food stored in the packaging material can effectively prevent condensation, spoilage, and oxidation due to oxygen or moisture, and can be easily stored for a long time.

[0089] According to one aspect of the present invention, the coating film 1 cm 2The sliding angle of the water droplet after attaching scotch tape to the size, placing a 100 g weight on it, and removing it after 1 hour may be 5 degrees or less, preferably 1 to 4 degrees, and more preferably 1.5 to 2 degrees, but is not limited thereto.

[0090] The above 'slip angle' refers to the angle of inclination at which liquid begins to flow based on a horizontal floor surface.

[0091] As the above sliding angle range is satisfied, the self-cleaning effect is further improved, which can prevent contamination of the packaging surface and has the advantage of saving cleaning costs, etc., as there is no need for separate cleaning.

[0092] The present invention can provide a self-cleaning food packaging material manufactured using the above composite coating film.

[0093] The above composite coating film effectively blocks oxygen and moisture and does not cause fogging on the surface, making it suitable for use as a food packaging material for long-term frozen and refrigerated storage.

[0094] In addition, the above composite coating film has the advantage of excellent transparency and an anti-fogging effect, making it easy for consumers to visually check the condition of food inside the food packaging.

[0095] In addition, the self-cleaning layer of the composite coating film has an excellent sliding angle, so that water or foreign substances do not adhere to the layer, thereby keeping the surface clean. In addition, even if stains or foreign substances adhere, they can be easily shaken off, so there is an advantage in that it is easy to manage.

[0096] Moreover, the composite coating film has the advantage of superior antibacterial effect compared to conventional packaging materials.

[0097] According to one aspect of the present invention, when the disk diffusion method is applied to the composite coating film, the sterilization diameter may be 0.5 cm or more, preferably the sterilization diameter may be 1.0 cm or more, and more preferably the sterilization diameter may be 1.5 to 2 cm, but is not limited thereto.

[0098] The composite coating film of the present invention has the advantage of excellent food preservation properties due to its excellent antibacterial effect as well as excellent permeability, low oxygen permeability and moisture permeability.

[0099] As described above, a method for manufacturing a composite coating film that is antibacterial, inhibits oxygen and moisture penetration, and is self-cleaning will be described.

[0100] The present invention can provide a method for manufacturing a composite coating film, comprising: a) a step of sequentially and alternately laminating a first dispersion containing chitin-based nanofibers substituted with guanidine groups and a second dispersion containing cellulose nanofibers on one surface of a film substrate to manufacture a barrier layer; b) a step of sequentially and alternately laminating a first dispersion containing chitin-based nanofibers substituted with guanidine groups and a third dispersion containing silica particles on the other surface of the film substrate to manufacture a self-cleaning layer; and c) a step of impregnating the self-cleaning layer with essential oil.

[0101] The present invention can provide chitin nanofibers substituted with guanidine groups, including the steps of: dispersing chitin in a solvent to prepare a dispersion; treating the dispersion with an acid or base; ultrasonicating the acid or base-treated dispersion to produce chitin nanofibers; and treating the nanofibers with a Lewis acid catalyst and cyanamide to ionize amino groups into guanidinium.

[0102] The Lewis acid catalyst may be one or two or more selected from the group consisting of scandium triflate (Sc(CF3SO3)3), lanthanum(III) trifluoromethanesulfonate (La(CF3SO3)3), ytterbium(III) trifluoromethanesulfonate (Yb(CF3SO3)3), zinc trifluoromethanesulfonate (Zn(CF3SO3)3), and bismuth(III) trifluoromethanesulfonate (Bi(CF3SO3)3).

[0103] The first dispersion of step a) can be prepared by mixing 0.1 to 1 wt% of the chitosan nanofibers with water or distilled water. The first dispersion can be titrated to a pH of 3 to 5 using a diluted hydrochloric acid aqueous solution, thereby further enhancing the cationic charge of the chitosan nanofibers. The second dispersion is prepared by anion-substituting the cellulose, and then mixing and dispersing the same in water. The content of the cellulose nanofibers in the second dispersion can be 0.01 to 1 wt%, and preferably 0.1 to 0.5 wt%, but is not limited thereto.

[0104] The above barrier layer was manufactured by alternately laminating the first dispersion and the second dispersion. The lamination method was performed alternately using a multilayer thin film lamination method, and the multilayer thin film lamination method was completed by spraying.

[0105] The spray was sprayed at a distance of 1 to 5 cm between one side of the film substrate and the spray nozzle, and the spray speed was 1 to 20 mm / s.

[0106] Since the number of injections and thickness are described above, detailed descriptions are omitted.

[0107] The third dispersion liquid of step b) is prepared by dispersing the silica particles in water. The content of the silica particles may be 0.5 to 3 wt%, preferably 1 to 2 wt%, but is not limited thereto.

[0108] The self-cleaning layer was manufactured by alternately laminating the first dispersion and the third dispersion. The lamination method was performed alternately using a multilayer thin film lamination method, and the multilayer thin film lamination method was completed by spraying.

[0109] The spray was sprayed at a distance of 1 to 5 cm between one side of the film substrate and the spray nozzle, and the spray speed was 1 to 20 mm / s.

[0110] Since the number of injections and thickness are described above, detailed descriptions are omitted.

[0111] According to one aspect of the present invention, after step a), a step of performing UV ozone treatment on the other surface of the film substrate may be further included.

[0112] By performing the above UV treatment, the surface of the film substrate is modified so that the self-cleaning layer can be deposited on the substrate more effectively.

[0113] According to one aspect of the present invention, after step e), a step of surface treatment of silica nanoparticles with a hydrophobic silane compound may be further included.

[0114] The above composite coating film is modified by impregnating it with the silane compound, and the modification temperature may be 80 to 120°C, but is not limited thereto.

[0115] According to one aspect of the present invention, the step of impregnating the self-cleaning layer with essential oil may be further included.

[0116] The types of essential oils mentioned above have been described in detail above, so description thereof is omitted.

[0117] The above impregnation method can be performed by spraying an appropriate amount of the above essential oil onto the upper portion of the self-cleaning layer to impregnate it, and after impregnation, the film substrate can be tilted to remove any residual oil.

[0118]

[0119] The present invention will be described in more detail based on the following examples and comparative examples. However, the following examples and comparative examples are merely illustrative examples for further explaining the present invention, and the present invention is not limited by the following examples and comparative examples.

[0120]

[0121] [Evaluation Method]

[0122] 1. Measurement of guanidine content

[0123] The guanidine content on the surface of chitin nanofibers was calculated by pH measurement. 0.05 g of guanidine chitosan nanowhiskers were dispersed in 10 mL of distilled water, adjusted to pH 1.5, and stirred for 24 hours. Afterwards, 0.01 M NaOH was added and the pH change was measured. The guanidine content was then calculated from the difference in the amine group content between the chitosan nanowhiskers and the chitin nanofibers. The amine content was defined by Equation 1 below. The mass of chitin nanofibers used for pH measurement was measured (m, unit g), and the amount of NaOH (mL) added up to the equivalence point was expressed as V 1, It is indicated as V2, and the NaOH concentration (mmol / mL) is indicated as C.

[0124]

[0125] [Formula 1]

[0126] Amine content (mmol / g) = (V2-V1)C / m

[0127]

[0128] 2. Measurement of light transmittance

[0129] The light transmittance of the antibacterial composite coating films manufactured in the examples and comparative examples was measured using UV-vis spectroscopy (V-770, Jasco). The light transmittance is the value measured at a wavelength of 550 nm.

[0130]

[0131] 3. Oxygen permeability measurement

[0132] Oxygen permeability was measured using an oxygen permeability tester (OX-TRAN 2 / 61, Mocon) according to ASTM D3985 conditions for the antibacterial composite coating films manufactured in the examples and comparative examples. The oxygen permeability was measured at room temperature (23°C) and relative humidity (RH) of 0%.

[0133]

[0134] 4. Measurement of moisture permeability

[0135] Moisture permeability was measured according to ASTM E96 conditions. The standard cup (vapometer permeability cup) purchased from Ez-cup consists of a donut-shaped lid with a diameter of 6.4 cm and a cup that can be filled with water below. The moisture permeability can be calculated by measuring the amount of moisture evaporated through the exposed surface of the film attached to the cup lid. The standard cup was filled with 100 g of distilled water, the sample film was placed on the lid, and the lid was closed to secure the film. The prepared standard cup was placed in a chamber maintained at room temperature (23°C) and a relative humidity (RH) of 50%. The weight change of the cup was measured after 24 hours to calculate the moisture permeability. The moisture permeability value was estimated using Equation 2 below.

[0136]

[0137] [Formula 2]

[0138] Moisture permeability (g / m) 2 day) = (Weight change of standard cup over 24 hours) / (Sample area)

[0139]

[0140] 5. Measurement of sliding angle

[0141] The sliding angle was recorded by placing the antibacterial composite coating film manufactured in the examples and comparative examples on a plate whose angle could be adjusted, dropping 50 μl of water droplets, and recording the angle at which the water droplets began to move.

[0142]

[0143] 6. Measurement of antibacterial properties

[0144] Antibacterial properties were measured using a disk-type antibacterial test on the antibacterial composite coating films manufactured in the Examples and Comparative Examples. The films were cut into 1-cm diameter circles, placed on culture media inoculated with microorganisms (E. coli), and incubated in a 37°C incubator for 24 hours. The diameter of the area around the film where no microorganisms grew was recorded.

[0145]

[0146] 7. Antibacterial measurement using shaking culture method

[0147] Antibacterial properties through shaking culture were evaluated by cutting 0.1 g of the antibacterial composite coating film manufactured in the examples and comparative examples into pieces and placing it in a solution cultured with microorganisms (E. coli), culturing it in a shaking incubator at 37°C, and measuring the absorbance (OD 600) at a wavelength of 600 nm every 2 hours. The composite coating film was placed in the log phase (OD 600 = 0.5) where microorganisms grow well.

[0148]

[0149] [Preparation of the first dispersion]

[0150] Chitin (Sigma-Aldrich, 5 g) was added to 3 M HCl (250 mL) and refluxed at 120 °C for 3 hours. The solution was then dialyzed to produce a chitin nanowhisker solution. Subsequently, 30 wt% NaOH was added and refluxed at 80 °C for 6 hours. The solution was then neutralized with 0.1 M HCl, dialyzed to remove residual salts, and lyophilized to obtain chitosan nanowhiskers.

[0151] The chitosan nanowhiskers (1 g) prepared above were dispersed in a 2% acetic acid solution (150 mL) and sonicated to prepare a dispersion. Scandium(III) triflate (0.03 g) and cyanamide (0.15 g) were added, and the mixture was refluxed at 100°C for 48 hours. Subsequently, the resulting mixture was dialyzed against distilled water to remove residual salts and lyophilized to obtain chitosan nanowhiskers surface-modified with guanidine (G-CsW).

[0152] The above-mentioned G-CsW was mixed with distilled water to prepare a 0.1 wt% G-CsW dispersion, and then the pH was adjusted to 4 with a 0.1 M HCl solution. The solution was sonicated for 10 minutes to prepare a first dispersion.

[0153]

[0154] [Preparation of the second dispersion]

[0155] Cellulose nanofibers were dispersed in distilled water to a concentration of 0.1 wt%, and then ultrasonicated for 10 minutes to prepare a second dispersion.

[0156] The above cellulose nanofibers were purchased as TEMPO-treated cellulose nanofibers, and the concentration of COO- functional groups in the treated nanofibers was 1.4 mmol / g.

[0157]

[0158] [Manufacturing of the third dispersion]

[0159] A third dispersion was prepared by dispersing 5-20 nanometer silica particles (Sigma-Aldrich) in distilled water to a concentration of 2 wt% and then ultrasonicating for 10 minutes.

[0160]

[0161] [Example 1]

[0162] Area is 15 cm 2After UV-treating the PET film at 50 degrees for 20 minutes, it was placed on an 80 degree heating plate, and the first dispersion and the second dispersion were laminated 40 times each using a multilayer thin film lamination method. The distance between the spraying line and the nozzle was 25 mm, and the speed was 10 mm / s.

[0163] The above-mentioned coated film was pressed using a heat press at 80 degrees for 10 minutes to produce a barrier layer.

[0164] After UV-treating the opposite side of the above-mentioned coated film for 15 minutes, the first dispersion and the third dispersion were alternately sprayed once using a multilayer thin film lamination method using a spray spraying device to complete a composite coating film.

[0165] The above composite coating film was placed together in a sealed container containing trichloro (octadecyl) silane and subjected to chemical vapor deposition of silane groups at 100°C for 3 hours.

[0166] 20 μl of oil mixed with castor oil and eugenol in a ratio of 7:3 was sprayed on the porous nano-coating layer of the above silane-deposited composite coating film to penetrate it, and the excess oil was removed by raising the film at a 90° angle to complete an antibacterial self-cleaning composite coating film.

[0167]

[0168] [Example 2]

[0169] In the above Example 1, when manufacturing a porous nano-coating layer, it was manufactured in the same manner as Example 1, except that the first dispersion and the third dispersion were sprayed alternately twice.

[0170]

[0171] [Example 3]

[0172] In the above Example 1, when manufacturing a porous nano-coating layer, it was manufactured in the same manner as Example 1, except that the first dispersion and the third dispersion were sprayed alternately three times.

[0173] [Example 4]

[0174] In the above Example 1, when manufacturing a porous nano-coating layer, it was manufactured in the same manner as Example 1, except that the first dispersion and the third dispersion were sprayed alternately four times.

[0175]

[0176] [Example 5]

[0177] In the above Example 4, it was manufactured in the same manner as Example 4, except that the oil was not impregnated.

[0178]

[0179] [Example 6]

[0180] In the above Example 4, the same method as Example 4 was used, except that castor oil and eugenol were mixed in a ratio of 2:8.

[0181]

[0182] [Example 7]

[0183] In the above Example 4, the same method as Example 4 was used, except that castor oil and eugenol were mixed in a ratio of 1:9.

[0184]

[0185] [Example 8]

[0186] In the above Example 4, it was manufactured in the same manner as Example 4, except that only castor oil was used.

[0187]

[0188] [Comparative Example 1]

[0189] In the above Example 8, it was manufactured in the same manner as Example 8, except that castor oil was used as mineral oil.

[0190]

[0191] [Comparative Example 2]

[0192] In the above Example 4, when producing the barrier layer and the porous layer, the first dispersion was produced in the same manner as Example 4, except that only a 0.1 wt% solution of chitosan nanowhiskers was used.

[0193]

[0194] [Comparative Example 2]

[0195] In the above Comparative Example 1, when producing the barrier layer and the porous layer, the first dispersion was produced in the same manner except that a 0.1 wt% solution of chitosan nanowhiskers was used.

[0196]

[0197] [Comparative Example 3]

[0198] PET film was used.

[0199]

[0200] (A) Coating layer thickness (㎛) (B) Coating layer thickness (㎛) 550 nm transmittance (%) Oxygen transmittance (ml / m 2 day)Moisture permeability (g / m) 2 (day)Slip angle (°)Antibacterial diameter (cm)Example 19.35.470<0.12.91.81.0Example 29.38.283<0.12.21.61.3Example 39.31.183<0.12.31.21.2Example 49.31.483<0.12.70.51.5Example 59.31.43.2<0.12.91.4(Roll off)0Example 69.31.482<0.12.31.21.1Example 79.31.481<0.12.11.80.8Example 89.31.482<0.12.22.00.6Comparative example 19.31483<0.12.52.00.5Comparative Example 281181<0.12.22.10.4Comparative Example 3008519.284.1300

[0201]

[0202] Figure 2 compares the growth scale of microorganisms by adding comparative examples and examples to the microbial culture solution. In Figure 2, the "Control" is described for comparison with the control group, in which nothing was added and the microorganisms grew well.

[0203] In Fig. 2, it was confirmed that microorganisms did not grow well in Example 4 compared to Control, Comparative Example 2, and Comparative Example 3, and through this, it was confirmed that the antibacterial effect of the composite coating film of the present invention is very excellent.

[0204]

[0205] As described above, the present invention has been described with specific details and limited examples and drawings, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0206] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the following claims as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. Description; A barrier layer in which a cellulose-based nanofiber layer and a chitin-based nanofiber layer substituted with a guanidine group are alternately laminated on one side of the above-described substrate; And a self-cleaning layer in which a chitin-based nanofiber layer and an inorganic particle layer substituted with a guanidine group are alternately laminated on the other surface of the above-described substrate; A composite coating film comprising a self-cleaning layer comprising essential oil.

2. In paragraph 1, A composite coating film comprising a barrier layer in which two or more layers of cellulose-based nanofiber layers and chitin-based nanofiber layers substituted with guanidine groups are alternately laminated on one surface of the above substrate, and a self-cleaning layer in which two or more layers of chitin-based nanofiber layers substituted with guanidine groups and inorganic particle layers are alternately laminated on the other surface of the above substrate.

3. In paragraph 1, A composite coating film comprising a guanidine content of 0.2 to 2 mmol / g per unit weight of chitin-based nanofibers surface-modified with the above guanidine.

4. In paragraph 1, A composite coating film, wherein the above essential oil comprises one or more selected from among eugenol, isoeugenol, castor oil, eugenol acetate, carvacrol, linalool, thymol, geraniol, geranylacetate, bicyclogermacrene, cinnamaldehyde, geranial, neral, 1,8-cineole, methyl chavicol, methyl cinnamate, methyl eugenol, camphor, α-thujone, viridiflorol, limonene, (Z)-linalool oxide, α-pinene, p-cymene, (E)-caryophyllene, and γ-terpinene.

5. In paragraph 1, A composite coating film wherein the above essential oil is a mixture of eugenol and castor oil in a ratio of 1:9 to 9:

1.

6. In paragraph 1, A composite coating film having a thickness of the barrier layer of 0.1 to 100 ㎛.

7. In paragraph 1, The above composite coating film is a composite coating film having a transmittance of 60 to 95% measured at a wavelength of 550 nm according to JIS-K-7105.

8. In paragraph 1, The above composite coating film has an oxygen permeability of 1 ml / m according to ASTM D3985. 2 Composite coating film with a lifespan of less than / day.

9. In paragraph 1, The above composite coating film has a moisture permeability of 10 g / m according to ASTM E96. 2 / day or less composite coating film.

10. In paragraph 1, 1 cm of the above composite coating film 2 A composite coating film having a sliding angle of a water droplet of 5 degrees or less after attaching scotch tape to the size, placing a 100 g weight on it, and removing it after 1 hour. (The above 'slip angle' refers to the angle of inclination at which liquid begins to flow based on a horizontal floor surface.) 11. In paragraph 1, A coating film having a sterilization diameter of 0.5 cm or more when the disk diffusion method is applied to the above composite coating film.

12. A self-cleaning food packaging material manufactured from a composite coating film selected from any one of claims 1 to 11. 13.a) A step of manufacturing a barrier layer by sequentially and alternately laminating a first dispersion containing chitin nanofibers substituted with guanidine groups dispersed on one surface of a film substrate and a second dispersion containing cellulose nanofibers dispersed; b) a step of sequentially and alternately laminating a first dispersion liquid in which chitin-based nanofibers substituted with the guanidine group are dispersed on the other surface of the film substrate and a third dispersion liquid in which silica particles are dispersed to produce a self-cleaning porous nano-coating layer; and c) a step of impregnating the self-cleaning porous nano-coating layer with essential oil; A method for manufacturing a composite coating film comprising:

14. In paragraph 13, A method for manufacturing a composite coating film, which further includes a step of UV ozone treatment on the other side of the film substrate after the above step a).

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