Hydrophilic coating compositions and methods for making the same

Abstract

The present disclosure relates to a hydrophilic coating composition comprising a thermoplastic resin modified with a hydrophilic substance, and a coating film having excellent scratch resistance, long-term driplessness, transparency, and non-tackiness can be obtained using the hydrophilic coating composition.

Description

Technical Field

[0001] This disclosure relates to a hydrophilic coating composition with excellent drip-free and scratch-resistant properties, a method for preparing the same, and a coating film utilizing the above composition. Background Technology

[0002] Most thermoplastic films used in plastic greenhouses are hydrophobic, condensing when the ambient temperature is below or equal to the dew point of water vapor, thus forming water droplets on the film surface. This phenomenon reduces sunlight transmittance, and the condensed water droplets fall onto the crops, potentially delaying growth or causing spoilage.

[0003] Korean patent KR10-2003-0093013A discloses the use of additives such as anti-drip agents, anti-dripping agents, and anti-fogging agents in film production. These additives are added along with the resin during film formation. After film formation, the additives migrate to the surface, simultaneously exerting their anti-drip effect. The anti-drip agent reduces the surface tension of the film, causing water droplets to form a thin water layer upon contact with the surface, thereby inhibiting condensation and improving transmittance. Since additive-type anti-drip agents function simultaneously with the migration of raw materials to the film surface, they initially provide good anti-drip properties, but this function is lost once the raw materials are exhausted. Therefore, when using agricultural films manufactured using existing methods, there is a problem of water vapor condensation recurring after a certain period.

[0004] To address these issues, Korean Patent Publication KR10-2019-0111143A discloses a technique for preparing hydrophilic coatings using inorganic colloidal sols such as silica and alumina, along with organosilanes and surfactants. Since hydrophilic colloidal particles do not adhere to the hydrophobic plastic film serving as the substrate, silane coupling agents are used as adhesives to enhance adhesion and improve the bond between the colloidal particles and the film. On the other hand, compositions containing these materials reduce the water contact angle of the plastic film or sheet, improving hydrophilicity, but suffer from poor scratch resistance, high-temperature hydrophilicity, and transparency after coating. Summary of the Invention

[0005] The purpose of this embodiment is to provide a hydrophilic coating composition with excellent scratch resistance and long-lasting non-drip properties.

[0006] The purpose of this embodiment is to provide a method for preparing a hydrophilic coating composition with excellent scratch resistance and long-lasting non-drip properties.

[0007] One embodiment aims to provide a coating film comprising the above-described hydrophilic coating composition.

[0008] In order to achieve the above objectives,

[0009] One aspect of the present invention provides a hydrophilic coating composition comprising: a thermosetting resin, a monomer derived from one or more monomers selected from the group consisting of primary amines, secondary amines and hydroxyl groups, an inorganic colloidal sol, and a silane coupling agent; wherein the thermosetting resin is modified with a hydrophilic substance.

[0010] In this case, the aforementioned thermosetting resin may include one or more selected from the group consisting of phenolic resin, polyurethane resin, melamine resin, urea resin, modified phenolic resin, modified melamine resin, modified melamine-urea resin, modified phenolic-urea resin, and modified polyurethane resin.

[0011] In addition, the monomers mentioned above may include melamine or phenolic compounds.

[0012] In addition, the aforementioned hydrophilic substances may include carbohydrates, polyols, or all of them.

[0013] Relative to the total weight of the composition, the above composition may contain 0.1 to 20% by weight of a thermosetting resin modified with hydrophilic additives; 50 to 90% by weight of an inorganic colloidal sol; and 0.1 to 5% by weight of a silane coupling agent.

[0014] The above composition may further contain a surfactant, which may be 0.1 to 10% by weight relative to the total weight of the composition.

[0015] The aforementioned inorganic colloidal sol can be one or more combinations selected from the group consisting of Al2O3, SiO2, ZnO, ZrO2, BaTiO3, TiO2, Ta2O5, Ti3O5, ITO, IZO, ATO, ZnO-Al, Nb2O3, SnO and MgO.

[0016] Another aspect of the present invention provides a method for preparing a hydrophilic coating composition, comprising the following steps: (a) mixing one or more monomers comprising the group consisting of primary amines, secondary amines and hydroxyl groups with a hydrophilic substance to prepare a hydrophilic modified thermosetting resin; and (b) mixing the modified thermosetting resin in a mixed solution comprising an inorganic colloidal sol and a silane coupling agent.

[0017] In this case, step (a) above can be carried out under conditions of pH 3 to 7.

[0018] In addition, in step (a) above, the monomer and the hydrophilic substance can be mixed in a weight ratio of 1:01 to 1:2.

[0019] Another aspect of the present invention provides a coating film comprising: a base film; and a coating layer comprising the hydrophilic coating composition thereon on the base film.

[0020] In this case, the base film may include a thermoplastic resin, which may be a polyolefin resin.

[0021] In addition, the above-mentioned coating can be an agricultural coating.

[0022] This disclosure relates to a hydrophilic coating composition comprising a thermoplastic resin modified with a hydrophilic substance, which can be used to obtain a coating film with excellent scratch resistance, long-term drip-free properties, and excellent transparency and non-stickiness. Detailed Implementation

[0023] The present invention will now be described in detail.

[0024] On the other hand, embodiments of the present invention can be modified in various different ways, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to provide a more complete explanation of the invention to those skilled in the art. Moreover, throughout the specification, the expression "comprising" a certain constituent element, unless specifically stated otherwise, implies that other constituent elements may be included, rather than excluding them.

[0025] One aspect of the present invention provides a hydrophilic coating composition comprising: a thermosetting resin derived from one or more monomers selected from the group consisting of primary amines, secondary amines and hydroxyl groups; an inorganic colloidal sol; and a silane coupling agent, wherein the thermosetting resin is modified with a hydrophilic substance.

[0026] At this point, the monomers mentioned above are monomers capable of reacting with hydrophilic substances. There are no particular limitations as long as they contain one or more of primary amine groups, secondary amine groups, and hydroxyl groups; for example, they may include melamine, phenolic resin, or urea. For example, the thermosetting resins mentioned above may be phenolic resins, polyurethane resins, melamine resins, urea resins, modified phenolic resins, modified melamine resins, modified melamine-urea resins, modified phenolic-urea resins, or modified polyurethane resins. The thermosetting resins mentioned above are preferably reaction products of compounds composed of the aforementioned monomers and hydrophilic substances. In one embodiment of the present invention, by using a hydrophilic substance containing hydroxyl groups instead of aldehydes such as formaldehyde in the condensation reaction with melamine, the resin is endowed with high hydrophilicity, allowing the resin to be strongly fixed to the membrane surface, thereby improving the scratch resistance of the membrane and significantly improving the effects of initial non-drip properties, long-term non-drip properties, and repeated non-drip properties (water resistance).

[0027] As an example of the aforementioned monomers, melamine has excellent crosslinking properties and is therefore used as a crosslinking agent in various industries. However, because melamine lacks hydrophilicity, its durability increases with increasing dosage, but its non-drip properties decrease. In cases of excessive use of melamine, the non-drip properties decrease rapidly, thus potentially limiting the amount that can be added.

[0028] The aforementioned hydrophilic substances may include, for example, carbohydrate compounds, polyols, or all of them; specifically, they may be monosaccharides, disaccharides, polysaccharides, glucose, fructose, etc. sucrose, maltose Lactose, dextrose, maltose Trehalose, fructose Polyols of C1-20, C1-15, C1-10, C1-5, or mixtures of two or more thereof. There are no particular limitations on the polyols mentioned above as long as they contain two or more hydroxyl groups (-OH) within their molecules. For example, they can be glycerol, diglycerol, triglyceride, polyglycerol, sorbitol, ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, butanedeol, pentanediol, hexanediol, pentaerythritol, xylitol, mannitol, pentaerythritol, but are not necessarily limited to these.

[0029] In the above-described hydrophilic coating composition, relative to the total weight of the composition, it may contain 0.1 to 20 wt% of a thermosetting resin modified with a hydrophilic substance, but is not necessarily limited to the above weight range; it may also contain 0.1 to 15 wt%, 0.5 to 15 wt%, 3 to 15 wt%, or 5 to 15 wt%. Furthermore, in the above-described hydrophilic coating composition, relative to the total weight of the composition, it may contain 50 to 90 wt% of an inorganic colloidal sol, but is not necessarily limited to the above weight range; it may also contain 60 to 90 wt%, or 65 to 85 wt%. Furthermore, in the above-described hydrophilic coating composition, relative to the total weight of the composition, it may contain 0.1 to 5 wt% of a silane coupling agent, but is not necessarily limited to the above weight range; it may also contain 0.1 to 4 wt%, 0.1 to 3 wt%, or 0.1 to 2 wt%.

[0030] The hydrophilic coating composition described above may also contain a surfactant. The surfactant may be selected from conventionally used nonionic, cationic, anionic, or amphoteric surfactants. The surfactant may be contained in 0.1 to 10% by weight relative to the total weight of the composition, but is not necessarily limited to this weight range; it may be contained in 0.5 to 8% by weight, 1 to 7% by weight, or 2 to 6% by weight.

[0031] The aforementioned inorganic colloidal sol may include at least one inorganic substance capable of reacting with a silane coupling agent. This inorganic substance may be inorganic nanoparticles with an average particle size of 1 to 100 nm. Examples of these inorganic nanoparticles include metal oxides, Al₂O₃, SiO₂, ZnO, ZrO₂, BaTiO₃, TiO₂, Ta₂O₅, Ti₃O₅, ITO, IZO, ATO, ZnO-Al, Nb₂O₃, SnO, or MgO. The aforementioned inorganic nanoparticles are uniformly formed within the coating film, thereby improving mechanical properties such as scratch resistance and pencil hardness. The aforementioned inorganic colloidal sol can be prepared directly for use, or it can be purchased commercially available. When using commercially available products, it can be used in a concentration of 10 to 80% by weight dispersed in a solvent. Alternatively, the aforementioned colloidal sol may also include alumina sol, silica sol, or all of them, and may contain a solid content of 10% to 50%, or 10% to 30%.

[0032] The aforementioned silan coupling agent possesses hydrolyzable groups that have affinity or reactivity with inorganic materials (silica, glass, metals, etc.) and organic functional groups that chemically bond with organic materials (organic synthetic resins, etc.), thereby enabling the bonding of inorganic and organic materials and improving mechanical strength, water resistance, and adhesion. Examples of silan coupling agents include epoxy silanes, silane esters, or acrylic silanes. Specific examples of silane coupling agents include glycidoxymethyltrimethoxysilane, 3-glycidoxypropyltrihydroxysilane, 3-glycidoxypropyldimethylhydroxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyltributoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexane)ethyltriethoxysilane, 5,6-epoxyhexyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, trimethoxysilane, triethoxysilane, and methyltrimethoxysilane. Methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, or 3-acryloyloxypropyltrimethoxysilane. Silane coupling agents can be bonded to inorganic materials via the sol-gel process. The hydrolyzed groups, after being hydrolyzed by water to become silanol groups (Si-OH), form hydrogen bonds with the -OH groups on the surface of inorganic colloidal particles and other inorganic materials. This enhances the bonding force between organic materials and difficult-to-bond inorganic materials. Furthermore, the organic functional groups react with reactive groups on the film surface, making the coating less susceptible to being washed away by water.

[0033] In one embodiment of the present invention, a condensation reaction is carried out by reacting with a hydrophilic substance containing hydroxyl groups to impart high hydrophilicity to the thermosetting resin. By using an inorganic colloidal sol, a silane coupling agent and the above-mentioned hydrophilic modified thermosetting resin together, the coating composition is strongly fixed to the membrane surface, thereby producing a membrane with improved scratch resistance, long-term maintenance of non-drip properties, high transparency and non-stickiness, and no adhesion between membrane surfaces.

[0034] Another aspect of the present invention provides a method for preparing a hydrophilic coating composition, comprising the following steps: mixing one or more monomers selected from the group consisting of primary amines, secondary amines and hydroxyl groups with a hydrophilic substance to prepare a hydrophilic modified thermosetting resin; and mixing the modified thermosetting resin in a mixed solution containing an inorganic colloidal sol and a silane coupling agent.

[0035] The preparation method of the above-mentioned hydrophilic coating composition will now be described in detail.

[0036] The method for preparing the above-mentioned hydrophilic coating composition includes a step of mixing one or more monomers selected from the group consisting of primary amines, secondary amines and hydroxyl groups with a hydrophilic substance to prepare a hydrophilic-modified thermosetting resin (hereinafter also referred to as the modification step). This step can be carried out under conditions of pH 3 to 7, but is not necessarily limited to these conditions; for example, it can also be carried out under conditions of pH 4 to 7 or 5 to 7. To adjust the pH range mentioned above, a pH adjuster can be used in the modification steps. The pH adjuster is not particularly limited, as long as it can adjust the pH of the mixed solution of the monomer and the hydrophilic substance to the range of 3 to 7. Examples of such substances include acetic acid, citric acid, phosphoric acid, hydrochloric acid, tartaric acid, succinic acid, malic acid, glycolic acid, fumaric acid, oxalic acid, itaconic acid, tricarboxylic acid, stearic acid, pyruvic acid, acetoacetic acid, pentene, benzoic acid, isocitrate, ascorbic acid, iminoacetic acid, propionic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, palmitic acid, or their salts.

[0037] In the above modification steps, conventional solvents can be used together, and there are no particular restrictions on the type of solvent. For example, distilled water, or organic solvents such as ethanol, methanol, acetone, dichloromethane, acetonitrile, hexane, cyclohexane, benzene, ethyl acetate, diethyl ether, tetrahydrofuran, butanol, toluene, carbon tetrachloride, chloroform, or dichloromethane can be selected.

[0038] In the above modification step, the mixed solution is stirred at 30°C to 100°C for 30 to 120 minutes to obtain a thermoplastic resin solution modified with hydrophilic substances. The above temperature conditions are not necessarily limited to these, for example, they can be carried out at 30°C to 80°C, 40°C to 80°C, 40°C to 70°C, or 40°C to 60°C. The above time conditions are also not necessarily limited to these, for example, they can be stirred for 30 to 100 minutes, 40 to 90 minutes, or 50 to 80 minutes.

[0039] In the above modification steps, the monomer and hydrophilic substance can be mixed in a weight ratio of 1:0.1 to 1:2, 1:0.1 to 1:1.5, 1:0.5 to 1:1.5, or 1:0.7 to 1:1.3, but are not necessarily limited to this.

[0040] The method for preparing the above-mentioned hydrophilic coating composition includes the step of mixing the modified thermosetting resin in a mixed solution containing an inorganic colloidal sol and a silane coupling agent.

[0041] The above-mentioned mixed solution containing inorganic colloidal sol and silane coupling agent may also contain conventional organic solvents. There are no particular restrictions on the type of organic solvent, such as distilled water, ethanol, methanol, acetone, dichloromethane, acetonitrile, hexane, cyclohexane, benzene, ethyl acetate, diethyl ether, tetrahydrofuran, butanol, toluene, carbon tetrachloride, chloroform, or dichloromethane.

[0042] When mixing the modified thermosetting resin in the above-mentioned mixed solution containing inorganic colloidal sol and silane coupling agent, a surfactant may also be added simultaneously for mixing. Then, the process may include stirring at 30°C to 80°C for 60 to 300 minutes. The temperature conditions are not necessarily limited to these; for example, they may be carried out at 30°C to 70°C, 40°C to 70°C, or 40°C to 60°C. Similarly, the time conditions are not necessarily limited to these; for example, they may be carried out for 100 to 280 minutes, 120 to 240 minutes, or 150 to 210 minutes.

[0043] Another aspect of the present invention provides a coating film comprising: a base film; and a coating comprising the above-described hydrophilic coating composition.

[0044] The aforementioned base film may include thermoplastic resins, which may include, for example, polyolefin resins, polyvinyl chloride resins, and polyester resins. Polyolefin resins include polyethylene, polypropylene, or ethylene copolymers, specifically linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer, ethylene-alkyl (meth)acrylate copolymer, ethylene-(meth)acrylate copolymer, or metal salts (ionomers) of ethylene-(meth)acrylate copolymers. Polyvinyl chloride resins may include polyvinyl chloride, vinyl chloride-ethylene copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-methyl methacrylate copolymer, or polyvinylidene chloride. Polyester resins may include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), or polybutylene naphthalate (PBN).

[0045] When the above-mentioned hydrophilic coating composition is coated onto a base film, it can be diluted in water for use, for example, at a dilution ratio of 1:2 to 1:20, 1:10 to 1:20, or 1:12 to 1:18. Typically, the surface of thermoplastic films such as polyolefin films is hydrophobic, therefore surface treatment can be performed to form reactive groups. Surface treatment methods include chemical treatment, corona discharge treatment, mechanical treatment, ultraviolet (UV) treatment, active plasma treatment, or glow discharge treatment, which can be selected and performed as appropriate.

[0046] As a method for coating the base film with the coating comprising the above-described hydrophilic coating composition, known coating methods can be used, such as gravure coating, spray coating, dip coating, flow coating, roll-to-roll coating, doctor blade coating, or air knife coating. After the above coating, a step of hot air drying at 50°C to 100°C for 30 seconds to 5 minutes may be further included. The temperature conditions are not necessarily limited to these; for example, they can also be performed at 60°C to 90°C. The time conditions are also not necessarily limited to these; for example, they can be performed for 30 seconds to 180 seconds or 60 seconds to 180 seconds.

[0047] The above-described coating can be used as an agricultural film. The agricultural film can be, for example, a film or sheet used for installing agricultural plastic greenhouses. In this case, additives used in the manufacture of agricultural films, such as anti-drip agents, anti-dripping agents, and anti-fogging agents, can also be used during the manufacturing of the film. Methods for carrying out the invention

[0048] The embodiments and experimental examples of the present invention will be specifically illustrated below. However, the embodiments and experimental examples described below are only illustrative of a part of the present invention, and the present invention is not limited thereto.

[0049] <Example 1-1> Preparation of Hydrophilic Coating Composition - 1

[0050] Step 1: Preparation of modified thermosetting resin (melamine resin)

[0051] 3g of liquid melamine and 6g of ethanol were mixed, and the pH was set to 6 using acetic acid. Then, 3g of glucose was added as a hydrophilic substance. The mixture was then stirred at 50°C for 1 hour to prepare a modified melamine resin solution as a modified thermosetting resin.

[0052] Step 2: Preparation of the hydrophilic coating composition

[0053] First, 70 wt% colloidal sol (colloidal silica, colloidal alumina), 10 wt% distilled water, 2 wt% ethanol, and 0.5 wt% silane coupling agent ((3-epoxypropoxypropyl)trimethoxysilane) were mixed and stirred at 300 rpm for 6 hours to obtain an opaque white solution. Then, 3 wt% of nonionic surfactant LA-7 (polyoxyethylene alkyl (C12-14) ether / ethoxylated (C12-14) alcohol, Cas No. 68439-50-9) and 9.5 wt% of the modified melamine resin solution prepared in step 1 above were added to this solution, and the mixture was stirred at 50°C for 3 hours to prepare a hydrophilic coating composition.

[0054] <Examples 1-2> Preparation of Hydrophilic Coating Compositions - 2

[0055] In step 1 of Example 1-1, fructose was added instead of glucose. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0056] <Examples 1-3> Preparation of Hydrophilic Coating Compositions - 3

[0057] In step 1 of Example 1-1, sucrose was added instead of glucose. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0058] <Examples 1-4> Preparation of Hydrophilic Coating Compositions - 4

[0059] In step 1 of Example 1-1, glycerol was added instead of glucose. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0060] <Examples 1-5> Preparation of Hydrophilic Coating Compositions - 5

[0061] In step 1 of Example 1-1, diglycerides were added instead of glucose. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0062] <Examples 1-6> Preparation of Hydrophilic Coating Compositions - 6

[0063] In step 1 of Example 1-1, pentaerythritol was added instead of glucose. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0064] <Examples 1-7> Preparation of Hydrophilic Coating Compositions - 7

[0065] In step 1 of Example 1-1, phenolic resin was used instead of melamine. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0066] <Examples 1-8> Preparation of Hydrophilic Coating Compositions - 8

[0067] In step 1 of Example 1-1, phenolic resin was used instead of melamine, and sucrose was used instead of glucose. Otherwise, the hydrophilic coating composition was prepared by the same method as in Example 1-1 above.

[0068] <Comparative Example 1-1> Preparation of Coating Compositions Containing Unmodified Thermosetting Resin - 1

[0069] In step 1 of Example 1-1, no hydrophilic substances or acetic acid were added; otherwise, the coating composition was prepared by the same method as in Example 1-1 above.

[0070] <Comparative Examples 1-2> Preparation of Coating Compositions Containing Unmodified Thermosetting Resins - 2

[0071] In Examples 1-7, hydrophilic substances and acetic acid were not added; otherwise, the hydrophilic coating compositions were prepared by the same method as in Examples 1-7 above.

[0072] The thermosetting resins and hydrophilic substances of Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-2 are listed in Table 1 below.

[0073] Table 1

[0074] thermosetting resins hydrophilic substances Example 1-1 melamine glucose Examples 1-2 melamine fructose Examples 1-3 melamine sucrose Examples 1-4 melamine glycerin Examples 1-5 melamine Diglycerides Examples 1-6 melamine Pentaerythritol Examples 1-7 Phenolic glucose Examples 1-8 Phenolic sucrose Comparative Example 1-1 melamine - Comparative Examples 1-2 Phenolic -

[0075] <Examples 2-1 to 2-8> Manufacturing of films coated with hydrophilic coating compositions

[0076] The hydrophilic coating compositions prepared in Examples 1-1 to 1-8 above were diluted with water at a ratio of 1:15 for later use. Using a corona discharge processor (manufactured by Matsubara Electric, corona surface voltage 220V, load-adj 0-10, load-current 0-10A, treatment rod 0.4m), a 0.1T thick linear low-density polyethylene (LDPE) film was subjected to discharge treatment under the conditions of load-adj 6, load-current 4A, and treatment rod 0.4m. After surface treatment, the film with a surface tension of 40-50 mN / m was immersed in the coating solution composition for coating (dip coating) and dried in an oven at 80°C for 2 minutes. The dried film was left at room temperature for at least 12 hours.

[0077] <Comparative Examples 2-1 to 2-2> Manufacturing of films coated with coating compositions

[0078] Using the coating compositions prepared in Comparative Examples 1-1 to 1-2 above, a film coated with the coating composition was manufactured by the same method as in Example 2-1 above.

[0079] <Experimental Example 1> Initial Drip-Free Properties Analysis of Coating

[0080] To confirm the initial anti-drip properties of the coating, a 40°C constant temperature bath was set up in a 20°C laboratory. The films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2 were attached to the upper part of the constant temperature bath, which was 25cm wide horizontally and 40cm wide vertically, with the bath tilted at 30°. The time taken from the setting of the constant temperature bath until the water droplet condensation area reached 10% was measured, and the results evaluated according to the following criteria are shown in Table 2 below. The shorter the elapsed time, the better the initial anti-drip properties.

[0081] A: Less than 10 minutes after setting

[0082] B: Set for a period of 10 minutes or more but less than 20 minutes.

[0083] C: Set for a time greater than or equal to 20 minutes and less than 30 minutes.

[0084] D: Set for 30 minutes or more

[0085] <Experimental Example 2> Analysis of the Long-Term Drip-Free Properties of the Coating

[0086] To confirm whether the non-drip properties of the coating were maintained over a long period, a 40°C constant temperature bath was set up in a 20°C laboratory. The films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2 were attached to the upper part of the constant temperature bath, which was 25cm wide horizontally and 40cm wide vertically, with the bath tilted at 30°. The degree of water droplet condensation on the film surface was observed visually for 20 days after the constant temperature bath was set up. The results of the evaluation according to the following criteria are shown in Table 2 below.

[0087] A: A transparent state where water droplets barely condense.

[0088] B: The water droplet condensation area is less than or equal to 25%.

[0089] C: A state where the water droplet condensation area is 25% to 50%.

[0090] D: The area of ​​water droplet condensation is greater than or equal to 50%.

[0091] <Experimental Example 3> Analysis of the Repeated Drip-Free Properties of the Coating

[0092] To confirm the water resistance of the coating, a 40°C constant temperature bath was set up in a 20°C laboratory. The films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2 were attached to the upper part of the constant temperature bath, which was 25cm wide horizontally and 40cm wide vertically, with the bath tilted at 30°. After 3 days in the constant temperature bath, the films were removed, allowed to dry completely at room temperature, and then placed back in the constant temperature bath. The degree of water droplet condensation on the film surface was observed visually. The results of the evaluation according to the following criteria are shown in Table 2 below.

[0093] A: The area of ​​water droplet condensation is less than or equal to 10%.

[0094] B: A state where the water droplet condensation area is 10% to 30%.

[0095] C: A state where water droplets condense over an area of ​​30% to 60%.

[0096] D: The area of ​​water droplet condensation is greater than or equal to 60%.

[0097] <Experimental Example 4> Scratch Resistance Analysis of Coating

[0098] The abrasion resistance of the coating was evaluated using a rubbing tester (manufactured by OCEAN SCIENCE, model: COAD.108, power: AC220V 60Hz). A 200g weight was applied as a load, and the coating was repeatedly rubbed 40 times at a certain speed. After setting up a 40°C constant temperature bath in a 20°C laboratory, the film to be tested was tilted at 30° to adhere to the upper part of the constant temperature bath. The area where the abrasion resistance decreased due to friction was then observed visually. The results of the evaluation based on the following criteria are shown in Table 2 below.

[0099] A: The area of ​​coating peeling is less than 10% of the total area.

[0100] B: The peeling area of ​​the coating ranges from 10% to 40% of the total area.

[0101] C: The peeling area of ​​the coating is between 40% and 80% of the total area.

[0102] D: The peeling area of ​​the coating is greater than or equal to 80% of the total area.

[0103] <Experimental Example 5> Film Coating Force Analysis of Coated Composition

[0104] In Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2, the films after dip-coating and hot air drying were observed with the naked eye, and the results of the evaluation according to the following criteria are shown in Table 2 below.

[0105] A: Coated uniformly over the entire membrane area

[0106] B: The area of ​​the mottled spots is less than 10% of the total area.

[0107] C: The area of ​​the mottled spots ranges from 10% to 50% of the total area.

[0108] D: The area of ​​the mottled spots is greater than or equal to 50% of the total area.

[0109] <Experimental Example 6> Adhesive Strength Analysis of Coatings

[0110] To confirm the adhesion of the coated surfaces, the films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2 were stacked with the coated surfaces facing each other, and after being stored in an 80°C oven for 24 hours with a weight of 20 kg, the force required for 180° peeling was measured using UTM. At this time, when the film was unfolded under high adhesion conditions, adhesion occurred between the coated surfaces. The measurement results are shown in Table 2 below.

[0111] <Experimental Example 7> Transparency Analysis of Coatings

[0112] To confirm the transparency of the films from Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2, the results measured using a colorimeter are shown in Table 2 below. In this case, the lower the result value, the more transparent the film.

[0113] Table 2

[0114]

[0115]

[0116] As can be confirmed from Table 2 above, the film coated with the hydrophilic coating composition containing the thermosetting resin modified with hydrophilic substances has excellent initial, long-term, repeated drip-free and scratch-resistant properties, and can be usefully used in the manufacture of agricultural films, etc. It also has excellent transparency and coating properties, and has the advantage of easy coating manufacturing process.

[0117] On the other hand, it is known that Comparative Examples 2-1 and 2-2, which were coated with a composition containing a thermosetting resin that has not been modified with hydrophilic substances, had excellent initial anti-drip properties, but poor long-term and repeated anti-drip properties, and were not suitable for use in agricultural films that require continuous anti-drip properties.

[0118] The present invention has been described in detail above through preferred embodiments and experimental examples, but the scope of the present invention is not limited to the featured embodiments and should be interpreted through the appended claims. Furthermore, those skilled in the art will understand that numerous modifications and variations can be made without departing from the scope of the present invention.

Claims

1. A hydrophilic coating composition characterized in that, comprising: a thermosetting resin derived from a monomer containing one or more selected from the group consisting of a primary amine group, a secondary amine group, and a hydroxyl group, an inorganic colloidal sol, a silane coupling agent; and a surfactant; wherein the thermosetting resin is modified with a hydrophilic substance, wherein the monomer includes melamine or phenol; and wherein the hydrophilic substance includes a saccharide compound or a polyol.

2. The hydrophilic coating composition according to claim 1, wherein the thermosetting resin includes one or more selected from the group consisting of a phenol resin, a polyurethane resin, a melamine resin, a urea resin, a modified phenol resin, a modified melamine resin, a modified melamine-urea resin, a modified phenol-urea resin, and a modified polyurethane resin.

3. The hydrophilic coating composition according to claim 1, wherein 0.1 to 20% by weight of the thermosetting resin modified with a hydrophilic substance, relative to the total weight of the composition; 65 to 85% by weight of the inorganic colloidal sol; 0.1 to 5% by weight of the silane coupling agent; and 0.1 to 10% by weight of the surfactant.

4. The hydrophilic coating composition according to claim 1, wherein the inorganic colloidal sol is one or a combination of two or more selected from the group consisting of Al203, Si02, ZnO, Zr02, BaTi03, Ti02, Ta205, Ti305, ITO, IZO, ATO, ZnO-Al, Nb203, SnO, and MgO.

5. A method of preparing a hydrophilic coating composition, characterized by, comprising the steps of: (a) mixing a monomer containing one or more selected from the group consisting of a primary amine group, a secondary amine group, and a hydroxyl group with a hydrophilic substance to prepare a thermosetting resin modified with a hydrophilic substance; and (b) mixing the modified thermosetting resin in a mixed solution containing an inorganic colloidal sol and a silane coupling agent, wherein the monomer includes melamine or phenol; and wherein the hydrophilic substance includes a saccharide compound or a polyol.

6. The method for preparing a hydrophilic coating composition according to claim 5, wherein the (a) step is performed at a pH of 3 to 7.

7. The method for preparing a hydrophilic coating composition according to claim 5, wherein in the (a) step, the monomer and the hydrophilic substance are mixed at a weight ratio of 1:01 to 1:

2.

8. A coated film comprising: a base film; and a coating layer containing the hydrophilic coating composition according to claim 1, coated on the base film.

9. The coated film according to claim 8, wherein the base film includes a thermoplastic resin.

10. The coated film according to claim 9, wherein the thermoplastic resin is a polyolefin-based resin.

11. The coated film according to claim 8, wherein the coated film is an agricultural coated film.

Images