Coating film composition having heat insulation properties, and coated metal sheet using same

Abstract

The present invention provides a coating film composition and a coated metal plate using the same, the coating film composition comprising a polymer resin, a foaming capsule, a plasticizer, and silica, the content of the foaming capsule being less than or equal to 100 parts by weight of the polymer resin, and the content of the silica being less than or equal to 100 parts by weight of the polymer resin. The coating composition comprises 0.1-10 parts by weight of the foaming capsule, 5-40 parts by weight of the plasticizer and 1-10 parts by weight of the silicon dioxide, the foaming capsule is in the form of a foaming capsule in which a foaming agent is contained in a thermoplastic plastic cell structure, and the weight ratio of the foaming capsule to the silicon dioxide is 1: 1-1: 10.

Description

Technical Field

[0001] The present invention relates to a coating composition and a steel plate having heat insulation properties for preventing condensation. The coating composition has heat insulation properties due to closed pores formed by foaming. The steel plate is made by coating the coating composition on a base metal plate. The steel plate is used as an outer plate of a household appliance, a roof material, a wall, etc. of a residential or factory building, etc. Background Art

[0002] like Figure 1 As shown, condensation refers to the phenomenon that water droplets condense on the inner surfaces of indoor walls and roofing materials that are in contact with the outside when there is a large temperature difference between the inside and outside of a home appliance such as a refrigerator or air conditioner, or when there is a large temperature difference between the inside and outside of a building in winter.

[0003] When condensation occurs between home appliances and buildings or structures, mold or ice may form on the wall, causing damage to the building structure. In the case of structures such as roofing materials of buildings where products are produced, water droplets generated by condensation may fall into the building, causing damage to the product.

[0004] Therefore, in order to always maintain the comfort of the living space, minimize energy loss, prevent the interior and exterior materials of the building from rotting and damage due to moisture, or prevent the loss of product production process, it is necessary to prevent condensation.

[0005] Generally, the roof materials and walls of buildings use highly insulating materials such as stone or wood, but the roof materials of factories or other buildings such as livestock houses or temporary sheds use steel plates due to the convenience and speed of their construction and maintenance. Steel plates frequently cause condensation and heat loss due to the high thermal conductivity of metal, so additional insulation treatment is required.

[0006] In the past, condensation has been prevented by various methods, including using an adhesive to bond a 4-6 mm thick sponge-like insulating material such as polyethylene to a steel plate material. However, in this case, there are problems in practical application due to the limited adhesive force of the adhesive and the complicated process.

[0007] There are also examples of adding porous inorganic particles or glass beads inside the polymer resin solution to create a porosity effect to exert the effect of preventing condensation. However, in this case, in the continuous production method of steel, the steel plate is wound in the form of a coil, and the glass beads break due to the load of the heavier steel, so that the heat insulation and condensation prevention effects cannot be obtained. In addition, the addition of excessive inorganic particles or glass beads causes the hardness of the coating to become hard, so the coating may break during stamping or bending.

[0008] [Prior art literature]

[0009] [Patent Document]

[0010] (Patent Document 1) Japanese Patent Publication No. 2001-270031 Summary of the invention

[0011] 1. Technical issues to be resolved

[0012] In order to solve the above technical problems, one aspect of the present invention provides a coating composition comprising a foaming agent in the form of capsules and having heat-insulating properties due to closed pores formed by foaming of the foaming agent.

[0013] Another aspect of the present invention provides a coated metal plate coated with the above-mentioned coating composition having heat-insulating properties.

[0014] (II) Technical solution

[0015] According to one embodiment of the present invention, there is provided a coating composition, which comprises: a polymer resin, a foaming capsule, a plasticizer and silica, wherein, relative to 100 parts by weight of the polymer resin, the coating composition comprises: 0.1-10 parts by weight of the foaming capsule, 5-40 parts by weight of the plasticizer, and 1-10 parts by weight of the silica, the foaming capsule is in the form of a foaming capsule containing a foaming agent in a thermoplastic plastic cell structure, and the weight ratio of the foaming capsule to the silica is 1:1 to 1:10.

[0016] According to another embodiment of the present invention, a coated metal plate is provided, which includes a base metal plate and an anti-condensation layer on at least one side of the base metal plate, the anti-condensation layer includes a porous coating layer and a pretreatment layer between the base metal plate and the porous coating layer, the porous coating layer contains the coating composition and includes closed pores.

[0017] (III) Beneficial effects

[0018] The coating formed by the coating composition of the present invention includes closed pores formed by the foaming of the foaming agent contained in the foaming capsule, and thus can not only prevent the formation of condensation by minimizing the temperature difference between the outside and the inside, but also has a heat-insulating effect of blocking external heat or cold and preventing internal heat and cold from radiating to the outside, thereby having the effect of saving energy.

[0019] Furthermore, the anti-dew condensation layer including the coating composition according to the present invention has high emissivity and strength, and has corrosion resistance that prevents the base metal plate from being corroded. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The principle of condensation is schematically shown.

[0021] Figure 2 This is a cross-sectional view schematically showing a cross section of a coated metal plate coated with the coating composition of the present invention.

[0022] Figure 3 The principle of heat insulation effect produced by coating a metal plate coated with the coating composition of the present invention is schematically shown.

[0023] Figure 4 A method for evaluating the effect of the coating composition of the present invention on preventing condensation is schematically shown. Best Mode for Carrying Out the Invention

[0024] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0025] According to one embodiment of the present invention, a coating composition comprising a polymer resin, foaming capsules, a plasticizer and silicon dioxide is provided. A coating formed from the coating composition can form closed pores by foaming of a foaming agent contained in the foaming capsules.

[0026] Based on 100 parts by weight of the polymer resin, the coating composition according to one embodiment of the present invention may include: 0.1-10 parts by weight of the foaming capsule, 5-40 parts by weight of the plasticizer, and 1-10 parts by weight of the silicon dioxide.

[0027] More specifically, based on 100 parts by weight of the polymer resin, the coating composition of the present invention may include: 0.1-5 parts by weight of the foaming capsule, 10-30 parts by weight of the plasticizer, and 1-10 parts by weight of the silicon dioxide.

[0028] The foam capsule may be in the form of a foam capsule containing a foaming agent in a thermoplastic cell structure, and the weight ratio of the foam capsule to the silicon dioxide may be 1:1 to 1:10.

[0029] More specifically, the weight ratio of the foaming capsule to the silicon dioxide may be 1:2 to 1:10.

[0030] More specifically, the weight ratio of the foaming capsule to the silicon dioxide may be 1:2 to 1:5.

[0031] Hereinafter, each component of the coating composition of the present invention will be described in more detail.

[0032] <Polymer resin>

[0033] The polymer resin included in the coating composition according to one embodiment of the present invention may be a polyvinyl chloride resin that can form a thick coating film using a liquid coating solution.

[0034] The polymer resin may use a polyvinyl chloride resin having a molecular weight of 3000 to 6000. When the molecular weight of the polymer resin is less than 3000, the weather resistance of the coating layer may be reduced, and when the molecular weight exceeds 6000, the viscosity increases rapidly, so the coating workability may be reduced. In addition to the polyvinyl chloride resin, the polymer resin may also use a polyurethane-based resin, but is not limited thereto.

[0035] <Plasticizer>

[0036] The coating composition according to one embodiment of the present invention may include a plasticizer for adjusting the viscosity and working properties of the polymer resin composed of polyvinyl chloride.

[0037] The plasticizer used in the polyvinyl chloride resin can be one or more selected from di-2-propylheptyl phthalate (DPHP), di-2-ethylhexyl adipate (DEHA), dimethyl adipate (DMAD), monomethyl adipate (MMAD), dioctyl adipate (DOA), dibutyl sebacate (DBS), dibutyl maleate (DBM), diisobutyl maleate (DIBM) and trimethylpentanediol diisobutyrate.

[0038] The content of the plasticizer may be 5-40 parts by weight, more preferably 10-30 parts by weight, based on 100 parts by weight of the polymer resin. When the content of the plasticizer is less than 5 parts by weight, the viscosity of the polyvinyl chloride solution is too high, and the workability may be reduced. On the other hand, when the content of the plasticizer exceeds 40 parts by weight, the viscosity is too low or the coating is too loose, and it may be difficult to maintain the steel plate coating to prevent condensation.

[0039] <Effervescent capsules and silicon dioxide>

[0040] The coating composition according to one embodiment of the present invention may include a foaming capsule, which may be a foaming capsule containing a foaming agent in a thermoplastic cell structure.

[0041] The thermoplastic plastic constituting the plastic cell structure of the foam capsule shell may be made of acrylonitrile copolymer-based plastic, and more specifically, may be made of styrene-acrylonitrile copolymer, but is not limited thereto.

[0042] The foaming agent contained in the foam capsule may be azodicarbonamide (ADCA), p,p'-oxybisbenzenesulfonylhydrazide (OBSH), hydrazinedicarbonamide (HDCA), dinitrosopentamethylenetetramine (DPT), etc. Preferably, an azodicarbonamide (ADCA)-based foaming agent may be used, but it is not limited thereto.

[0043] The foaming capsule can preferably withstand at least 200 kg / cm after the foaming process. 2 When it cannot support 200kg / cm 2 When the load is too great, the pores that are closed after the coating is manufactured cannot support the load of the steel plate, and the pores are destroyed, so the thermal insulation performance may be weakened.

[0044] The average particle size of the foaming capsules may be 1-20 μm. When the average particle size of the foaming capsules is less than 1 μm, the size of the closed pores after foaming is too small, and it may be difficult to obtain the heat insulation effect of the pores. On the other hand, when the average particle size of the foaming capsules exceeds 20 μm, the size of the closed pores after foaming is too large, and the toughness of the coating film is reduced, so the problem of reduced physical properties of the coating film during processing may occur.

[0045] In the coating composition according to one embodiment of the present invention, the content of the foaming capsules may be 0.1-10 parts by weight, more preferably 0.1-5 parts by weight, and more preferably 1-5 parts by weight, based on 100 parts by weight of the polymer resin. When the content of the foaming capsules is less than 0.1 parts by weight, the formation of closed pores caused by foaming is insufficient, and the heat insulation performance may be weakened. When the content of the foaming capsules exceeds 10 parts by weight, the viscosity of the solution increases when the solution is prepared, and the coating operation may become difficult.

[0046] In addition, the coating composition according to one embodiment of the present invention may include silicon dioxide to improve the strength and emissivity of the coating, and the silicon dioxide may be in the form of silicon dioxide powder. In addition to silicon dioxide, at least one of calcium carbonate (CaCO3), titanium dioxide (TiO2) and magnesium hydroxide (Mg(OH)2) may be further used.

[0047] The average particle size of the silicon dioxide powder may be 10-25 μm. When the average particle size of the silicon dioxide is less than 10 μm, an excessive amount of silicon dioxide needs to be added to achieve the desired glossiness, so the problem of increased viscosity or increased cost may occur. When the average particle size of the silicon dioxide exceeds 25 μm, the surface of the coating may become too rough.

[0048] In the coating composition according to one embodiment of the present invention, the content of the silicon dioxide may be 1-10 parts by weight based on 100 parts by weight of the polymer resin. When the content of the silicon dioxide is less than 1 part by weight, it may not have an effect on the improvement of the emissivity and the improvement of the strength of the coating film. When the content of the silicon dioxide exceeds 10 parts by weight, the brittleness of the coating film may be increased and the processability may be deteriorated, and the foaming property of the coating film may be hindered.

[0049] In the coating composition of the present invention, the foaming capsule and the silica may be contained in a weight ratio of 1:1 to 1:10, may be contained in a weight ratio of 1:2 to 1:10, more preferably may be contained in a weight ratio of 1:2 to 1:8, and further preferably may be contained in a weight ratio of 1:2 to 1:5.

[0050] When the weight ratio of silica to foaming capsule is less than 1:1, there is an advantage that foaming is performed relatively efficiently, but the content of silica is insufficient, and it may be difficult to expect an increase in emissivity, and the hardness of the coating may be deteriorated. When the weight ratio of silica to foaming capsule exceeds 1:10, due to the excess silica, the hardness of the coating is too high, the brittleness of the coating increases, the processability may be deteriorated, and the formation of closed pores may be limited.

[0051] <Additives>

[0052] The coating composition according to one embodiment of the present invention may include other additives. The specific substances and their contents included in the additives are well known in the art, so when preparing the coating, the technician can appropriately select and use them, and the type and content of the additives are not particularly limited.

[0053] For example, the additive may include one or more of a pigment, a defoamer, a leveling agent, a dispersant, a flame retardant, and a UV stabilizer. The additive may be added in an amount of 1.0-10 parts by weight based on 100 parts by weight of the polymer resin as required.

[0054] In the coating composition according to one embodiment of the present invention, a pigment having an inherent color may be used as an additive for aesthetic purposes, and the pigment may be realized in various colors by mixing black, red, yellow, and white pigments at a predetermined mixing ratio.

[0055] Examples of the black pigment include carbon black, carbon nanotubes, graphite, graphene, etc., and may include at least one selected from iron oxide (Fe2O3), titanium dioxide (TiO2), carbon black, carbon nanotubes, graphite and graphene. Examples of red pigment include iron oxide (Fe2O3). Examples of white pigment include titanium dioxide (TiO2). Examples of yellow pigment include strontium chromate (Strontium Chromate).

[0056] The coating composition of the present invention may contain a solvent to adjust the viscosity. The solvent may be selected from, for example, toluene, xylene, isopropyl alcohol, solvent naphtha, cellosolve, acetic cellosolve and butyl cellosolve. The solvent may be a mixture of one or more. In order to adjust the viscosity of the coating composition, the content of the solvent added to the composition may be appropriately adjusted as needed, and is not particularly limited herein.

[0057] <Painted Metal Sheet>

[0058] According to another embodiment of the present invention, a coated metal plate is provided, the coated metal plate comprising: a base metal plate; and an anti-condensation layer having heat insulation properties on at least one side of the base metal plate. The anti-condensation layer may include a porous coating layer and a pretreatment layer between the base metal plate and the porous coating layer. The porous coating layer is formed by a coating film coated with the coating composition of the present invention, and may include closed pores formed by foaming of a foaming agent contained in a foaming capsule of the coating composition of the present invention.

[0059] The coated metal sheet according to one embodiment of the present invention comprises the porous coating film layer having closed pores formed by the coating film composition of the present invention, so that Figure 3 As shown, not only can the formation of condensation be prevented by minimizing the temperature difference between the outside and the inside, but also the heat insulation effect of blocking the outside heat or cold and preventing the heat and cold inside from being dissipated to the outside has the effect of saving energy. In addition, the coated metal plate of the present invention can have excellent corrosion resistance, high emissivity and high strength by forming an anti-condensation layer including the porous coating layer on at least one side of the base metal plate.

[0060] Below, refer to Figure 2 , a coated metal sheet according to an embodiment of the present invention is described in more detail.

[0061] A coated metal plate according to an embodiment of the present invention may include a base metal plate and an anti-dew condensation layer formed on one or both surfaces of the base metal plate.

[0062] The coated metal plate can be manufactured by coating the composition for forming the pretreatment layer on a base metal plate and then coating the coating composition thereon after drying. In this case, the formation of the pores caused by the foaming of the foaming capsules can be formed when the coating composition is dried and cured after coating. The foaming, drying and curing can be performed simultaneously.

[0063] The parent metal plate may be one selected from a cold-rolled steel plate, a hot-rolled steel plate, a galvanized steel plate, a galvanized alloy steel plate, an aluminum plate and stainless steel, but is not limited thereto.

[0064] The thickness of the parent metal plate may be 0.25 mm to 4.5 mm, but is not limited thereto.

[0065] The anti-condensation layer may include: a porous coating layer, which contains the coating composition of the present invention; and a pretreatment layer, which is formed between the parent metal plate and the porous coating layer to enhance the corrosion resistance of the parent metal plate and the coating adhesion between the parent metal plate and the porous coating layer.

[0066] As the composition for forming the pretreatment layer, acrylic resin, epoxy resin, phenolic resin, xylene resin, polyester resin, polyurethane resin, etc. can be used, and acrylic resin can be used preferably. The acrylic resin can be urethane acrylate, epoxy acrylate, etc., but is not limited thereto.

[0067] The thickness of the pretreatment layer may be 0.1-1 μm. When the thickness of the pretreatment layer is less than 0.1 μm, the adhesion with the porous coating layer coated on the pretreatment layer may be insufficient, and when the thickness of the pretreatment layer exceeds 1 μm, the pretreatment layer treatment requires too much resin composition, which may be uneconomical.

[0068] The thickness of the porous coating layer may be 50-400 μm. When the thickness of the porous coating layer is less than 50 μm, the effects of heat insulation, condensation prevention and energy saving may be weakened. On the other hand, when the thickness of the porous coating layer exceeds 400 μm, the forming process of the coated metal plate becomes difficult due to the excessive thickness of the coating layer, and the production requires too high a cost, so it may be uneconomical.

[0069] The average particle size of the closed pores may be 5-50 μm. When the average particle size of the closed pores is less than 5 μm, the size of the pores is too small, and it may be difficult to obtain the heat insulation effect of the pores. When the average particle size of the closed pores exceeds 50 μm, the size of the pores in the coating film is too large, the strength of the coating film is reduced, and the problem of reduced physical properties of the coating film during processing may occur.

[0070] The porous coating layer may include closed pores formed by coating the coating composition according to one embodiment of the present invention and foaming.

[0071] More specifically, the coating composition according to one embodiment of the present invention can be coated on a base metal plate and dried and cured at 185-240°C, and the closed pores can be formed by foaming the foaming capsules contained in the coating composition of the present invention during drying and curing.

[0072] When the drying and curing temperature is lower than 185°C, the foaming degree is weak and the average particle size of the closed pores becomes smaller, so it may be difficult to obtain the heat insulation effect of the pores. When the drying and curing temperature exceeds 240°C, the average particle size of the closed pores exceeds 50 μm or the foaming capsules are destroyed, so the pores may be open.

[0073] As a method for coating the coating composition of the present invention and / or the composition for forming the pretreatment layer on the parent metal plate for manufacturing a coated metal plate according to one embodiment of the present invention, an existing known method can be applied. For example, flow coating, roller coating, shower coating, scraper coating, spin coating and rod coating can be used. In addition, spray coating, airless spray coating, air spray coating, brush coating and the like can also be used. These coating methods can use an automated method or a manual coating method. DETAILED DESCRIPTION

[0074] <Example>

[0075] Hereinafter, examples of the present invention and comparative examples will be described. However, the examples of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the examples described below.

[0076] 1. Manufacture of coated metal sheets

[0077] Example 1

[0078] After adding 100 g of polyvinyl chloride resin as a polymer resin, 20 g of di-2-propylheptyl phthalate (DPHP) as a plasticizer, 1 g of foaming capsules, 5 g of silica and 5 g of a pigment (titanium dioxide, TiO2) as an additive, 10 g of a solvent (solvent naphtha) and stirring to prepare a coating composition.

[0079] The foam capsules are foam capsules with an average particle size of 10-15 μm and an azodicarbonamide foaming agent contained in an outer shell composed of styrene-acrylonitrile copolymer.

[0080] A galvanized steel sheet having a size of 20×20 cm was prepared, on which the urethane acrylate solution was coated in a thickness of 1 μm and then cured at 150° C. to form a pretreatment layer.

[0081] In order to form a porous coating layer on the pretreatment layer, the prepared coating composition was coated in a thickness of 50 μm by a bar coating method and dried at 224° C. for 30 seconds to manufacture a coated metal plate.

[0082] Example 2

[0083] A coated metal plate was manufactured by the same method as in Example 1, except that the coating composition was applied in a thickness of 100 μm.

[0084] Example 3

[0085] A coated metal plate was manufactured by the same method as in Example 1, except that the coating composition was applied in a thickness of 200 μm.

[0086] Example 4

[0087] A coated metal plate was manufactured by the same method as in Example 1, except that the coating composition was applied in a thickness of 400 μm.

[0088] Example 5

[0089] The coating composition was prepared by the same method as the coated metal plate of Example 1, except that 1 g of silica was added during the preparation of the coating composition so that the weight ratio of the foaming capsule to the silica was 1:1.

[0090] Example 6

[0091] The coating composition was prepared by the same method as the coated metal plate of Example 1, except that 2 g of silica was added during the preparation of the coating composition so that the weight ratio of the foaming capsule to the silica was 1:2.

[0092] Example 7

[0093] The coating composition was prepared by the same method as the coated metal plate of Example 1, except that 3 g of silica was added during the preparation of the coating composition so that the weight ratio of the foaming capsule to the silica was 1:3.

[0094] Example 8

[0095] The coating composition was prepared by the same method as the coated metal plate of Example 1, except that 10 g of silica was added when preparing the coating composition so that the weight ratio of the foaming capsule to the silica was 1:10.

[0096] Comparative Example 1

[0097] A galvanized steel sheet having a size of 20×20 cm was prepared.

[0098] Comparative Example 2

[0099] In the case of Comparative Example 2, a conventional color-coated steel plate (product of POSCO STEELEON) with a size of 20×20 cm that is currently mass-produced and sold on the market is used. The structure of the coating film is a color-coated steel plate consisting of a 1 μm pretreatment layer, a 5 μm polyester resin primer layer, and a 20 μm polyester resin color coating layer.

[0100] Comparative Example 3

[0101] The coating composition was prepared by the same method as the coated metal plate of Example 1, except that 11 g of silica was added when preparing the coating composition so that the weight ratio of the foaming capsule to the silica was 1:11.

[0102] 2. Evaluation criteria for properties of painted metal sheets

[0103] The coating properties were evaluated based on the coating thickness for Examples 1 to 4, Comparative Examples 1 and 2, and the coating properties were evaluated based on the content ratio of the foaming agent to silica for Examples 1, 5 to 8, and Comparative Example 3. The evaluation criteria are as follows.

[0104] (1) Corrosion resistance

[0105] The corrosion resistance was evaluated by spraying 5% salt water on the test piece at 35° C., and measuring the surface area of ​​the corroded portion relative to the total surface area of ​​the coated metal plate 720 hours later to evaluate the degree of corrosion.

[0106] [Bad]: After 720 hours, more than 5% of the total surface area of ​​the coated metal plate was corroded

[0107] [Good]: After 720 hours, less than 5% of the total surface area of ​​the coated metal panel is corroded

[0108] (2) Anti-condensation properties

[0109] The evaluation of anti-condensation performance is as follows Figure 4 As schematically shown in the figure, a box was made using the coated metal plates made using the embodiments and comparative examples of the present invention, and ice was filled inside the box to evaluate whether water droplets were formed on the outer surface. In detail, a box with a size of 200 mm (W) × 200 mm (D) × 200 mm (H) was made using the coated metal plates made using the embodiments and comparative examples. In addition, the box was filled with ice and placed in an environment of room temperature (25°C) and relative humidity of 50% for 30 minutes, and then the presence of water droplets on the surface of the box was evaluated.

[0110] [Bad]: There are condensation drops on the entire surface of the box

[0111] [Normal]: Water droplets have condensed on some surfaces of the box

[0112] [Good]: There is no condensation on the entire surface of the box

[0113] (3) Thermal insulation

[0114] The thermal insulation is evaluated by the guarded hot plate method, where the coated metal plate is placed between a hot plate and a cold plate and adhered, and then the amount of heat flowing from the top to the back of the steel plate is measured within 1 hour. The less heat that flows, that is, the lower the thermal conductivity, the better the thermal insulation performance.

[0115] (4) Emissivity

[0116] Evaluation of emissivity The emissivity of the steel sheet was measured in the wavelength band of 5 to 20 μm, which is an infrared wavelength band, according to the KS standard (KS L 2514) prescribed as an emissivity measurement test by the Korea Construction and Living Environment Testing Institute.

[0117] (5) Foaming properties

[0118] The foaming property of the foaming capsules contained in the coating composition was determined by visually identifying the surface of the coating film with a 15x magnifying glass after the foaming process, and measuring the number of capsules per 1 cm 2 Check whether there is an unfoamed part.

[0119] [Bad]: There is more than 10% unfoamed area on the coated surface (10% ≤ the area of ​​unfoamed area)

[0120] [Normal]: There is less than 10% unfoamed area on the coated surface (0% < area of ​​unfoamed area < 10%)

[0121] [Good]: There is no unfoamed portion on the coated surface (unfoamed portion area: 0%).

[0122] (6) Coating hardness

[0123] The hardness of the coating film is determined by moving a fingernail back and forth 20 times on the cured coating film in the same direction as the coating direction and in a direction perpendicular to the coating direction, and then observing the scratches remaining on the coating film. The observation results are evaluated by the following method.

[0124] [Good]: No traces

[0125] [Normal]: Leaves a trace, but it recovers and disappears within 60 seconds

[0126] [Bad]: There are traces

[0127] (7) Coating processability

[0128] The coating processability was evaluated by bending the applied coating film at 180 degrees and then evaluating whether cracks were generated in the total area of ​​the processed coating film.

[0129] [Bad]: Cracks in the coating

[0130] [Good]: No cracks in the coating film

[0131] 3. Results of evaluation of properties of coated metal sheets

[0132] (1) Evaluation results of coated metal sheet characteristics according to coating film thickness

[0133] For Examples 1 to 4 and Comparative Examples 1 and 2, evaluation of coating film properties according to coating film thickness was performed.

[0134] 1) Corrosion resistance evaluation results

[0135] The corrosion resistance evaluation results are shown in Table 1 below.

[0136] [Table 1]

[0137]

[0138] The corrosion resistance evaluation results showed that 100% of the total surface area of ​​the metal plate was corroded in Comparative Example 1, and 10% of the total surface area of ​​the metal plate was corroded in Comparative Example 2, but the corroded area was 0% in Examples 1 to 4 of the present invention. The above results confirmed that the coated metal plate of the present invention has excellent corrosion resistance.

[0139] 2) Evaluation results of anti-condensation performance

[0140] The evaluation results of the anti-condensation property are shown in Table 2 below.

[0141] [Table 2]

[0142]

[0143] As for the evaluation results of the anti-condensation property, condensation was observed on the entire surface of the boxes made of the coated metal plates in Comparative Examples 1 and 2, but no water droplets were condensed on the entire surface of the boxes of Examples 1 to 4. The above results confirm that the coated metal plates of the present invention have excellent anti-condensation properties.

[0144] 3) Thermal insulation evaluation results

[0145] The thermal insulation evaluation results are shown in Table 3 below.

[0146] [Table 3]

[0147]

[0148] The thermal insulation evaluation results showed that the thermal conductivity of the metal plates of Comparative Examples 1 and 2 was 40 W / mK or more, but the thermal conductivity of Examples 1 to 4 of the present invention was 2 W / mK or less. The above results confirmed that the coated metal plate of the present invention has excellent thermal insulation performance.

[0149] 4) Emissivity evaluation

[0150] The emissivity evaluation results are shown in Table 4 below.

[0151] [Table 4]

[0152]

[0153] The emissivity evaluation results showed that Comparative Example 1 was 0.55 and Comparative Example 2 was 0.80, but Examples 1 to 4 of the present invention all showed high emissivity of 0.90 or more. The above results confirmed that the coated metal plate of the present invention has excellent emissivity.

[0154] (2) Evaluation results of the properties of coated metal sheets according to the content ratio of foaming agent and silica

[0155] For Example 1, Examples 5 to 8, and Comparative Example 3, evaluation of coating film properties according to the content ratio of the foaming agent and silica was performed.

[0156] The evaluation results are shown in Table 5 below.

[0157] [Table 5]

[0158]

[0159] According to the evaluation results of the coating film characteristics based on the content ratio of the foaming agent to the silica, in the case of Comparative Example 3 in which the ratio of the foaming agent to the silica was 1:11, since the coating film composition contained an excessive amount of silica, the brittleness of the coating film increased, thereby generating cracks, and since the formation of silica closed pores was limited, the number of cracks per 1 cm was measured. 2 More than 10% of the area of ​​the coating surface is free of closed pores caused by the foaming capsules. On the other hand, in the case of Examples 1, 5 to 8 of the present invention in which the ratio of the foaming agent to the silica is 1:1 to 1:10, the closed pores are normally formed, and the coating has excellent corrosion resistance and anti-condensation properties while having low thermal conductivity, and the coating has a hardness of more than average and good coating processability.

Claims

1. A coating composition comprising: a polymer resin, a foaming capsule, a plasticizer and silicon dioxide, in, Relative to 100 parts by weight of the polymer resin, the coating composition comprises: 0.1-10 parts by weight of the foaming capsule, 5-40 parts by weight of the plasticizer, and 1-10 parts by weight of the silicon dioxide. The foam capsule is in the form of a foam capsule containing a foaming agent in a thermoplastic cell structure. The weight ratio of the foaming capsule to the silicon dioxide is 1:1 to 1:

10.

2. The coating composition according to claim 1, wherein The polymer resin is polyvinyl chloride resin or polyurethane resin.

3. The coating composition according to claim 1, wherein The plasticizer is one or more selected from di-2-propylheptyl phthalate (DPHP), di-2-ethylhexyl adipate (DEHA), dimethyl adipate (DMAD), monomethyl adipate (MMAD), dioctyl adipate (DOA), dibutyl sebacate (DBS), dibutyl maleate (DBM), diisobutyl maleate (DIBM) and trimethylpentanediol diisobutyrate.

4. The coating composition according to claim 1, wherein The average particle size of the foam capsule is 1-20 μm.

5. The coating composition according to claim 1, wherein The coating composition further comprises one or more additives selected from the group consisting of a diluent, a pigment, a surfactant, an antibacterial agent, an antifungal agent, a matting agent, a defoaming agent, a thickener, an anti-settling agent, a leveling agent, a dispersant, a heat stabilizer, a wax component, and an ultraviolet absorber.

6. A coated metal plate, comprising a base metal plate and an anti-condensation layer on at least one side of the base metal plate, the anti-condensation layer comprising a porous coating layer and a pretreatment layer arranged between the base metal plate and the porous coating layer, the porous coating layer comprising the coating composition described in any one of claims 1 to 5 and including closed pores.

7. The coated metal sheet according to claim 6, wherein: The parent metal plate is selected from cold-rolled steel plate, hot-rolled steel plate, galvanized steel plate, galvanized alloy steel plate, aluminum plate and stainless steel plate.

8. The coated metal plate according to claim 6, wherein: The thickness of the parent metal plate is 0.25 mm to 4.5 mm.

9. The coated metal plate according to claim 6, wherein: The pretreatment layer is formed by coating at least one surface of the base metal plate with a composition comprising one or more selected from acrylic resin, epoxy resin, phenolic resin, xylene resin, polyester resin and polyurethane resin.

10. The coated metal sheet according to claim 6, wherein The thickness of the pretreatment layer is 0.1-1 μm.

11. The coated metal sheet according to claim 6, wherein: The average particle size of the closed pores is 5-50 μm.

12. The coated metal sheet according to claim 6, wherein: The thickness of the porous coating layer is 50-400 μm.

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