Coating composition for heat insulation and sound absorption, and coated steel sheet having excellent heat insulation and sound absorption characteristics using same

Abstract

The present invention relates to a coating composition for heat insulation and sound absorption and a coated steel sheet having excellent heat insulation and sound absorption characteristics using the same, and more particularly, to a coating composition for heat insulation and sound absorption, a coated steel sheet using the same, and a method for manufacturing the same, the coating composition for heat insulation and sound absorption comprising: a polyvinyl chloride resin; a plasticizer; foaming the capsule; the foaming capsule is a foaming capsule with a core-shell structure, and the foaming capsule is composed of a polymer shell and a foaming agent core.

Description

Technical Field

[0001] This invention relates to a coating composition for heat insulation and sound absorption, and a coated steel sheet utilizing the superior heat insulation and sound absorption properties thereof. More specifically, it relates to a coating composition and a coated steel sheet utilizing the same, which exhibits superior heat insulation performance, reflective properties, and noise reduction properties, and can maintain these superior heat insulation performance and noise reduction properties stably over a long period of time. This allows it to be used as a building roofing material, etc., to improve the cooling / heating efficiency of buildings and eliminate the inconvenience caused by noise. Background Technology

[0002] In the past, in order to achieve thermal insulation performance, thermal insulation coating compositions were used that mixed friction materials such as silica sand, bauxite, sand, and steelmaking slag, or retroreflective hollow materials, with organic solvent-based adhesive resins of the epoxy, acrylic, and urethane types.

[0003] However, this type of heat-insulating coating composition uses organic solvents with strong odors that are harmful to the human body. These components may damage health when they evaporate, and there are also environmental problems.

[0004] In addition, while water-based coating compositions may pose less harm to the human body, they may have issues such as poor film adhesion or cracking, and in summer, the film may become sticky and cause pollution due to high temperatures.

[0005] Furthermore, this type of coating needs to be applied to a certain thickness in millimeters, and the drying time can range from several minutes to several hours, which limits its application to steel plates. Therefore, noise reduction often requires the application of sound-absorbing plastic foam several millimeters thick, necessitating additional bonding processes and increasing costs due to the use of foam-like films. For example, Korean Patent Application No. 10-2021-0180153 discloses a technique for a polyurethane foam composition for improving the sound absorption performance of sound-absorbing materials.

[0006] Therefore, when a coating composition for steel sheet can provide excellent heat insulation and sound absorption capabilities even when the coating thickness is in the form of a thin film, it is expected to be effectively applied in related fields. Summary of the Invention

[0007] (a) Technical problems to be solved One aspect of the present invention is to provide a coating composition for steel plates with excellent heat insulation and sound absorption capabilities.

[0008] Another aspect of the present invention is to provide a steel plate with excellent heat insulation and sound absorption capabilities.

[0009] Another aspect of the present invention is to provide a method for manufacturing a steel plate with excellent heat insulation and sound absorption capabilities.

[0010] (II) Technical Solution According to one aspect of the present invention, a coating composition for heat insulation and sound absorption is provided, comprising: polyvinyl chloride resin; plasticizer; foaming capsule; and ceramic-based heat-insulating pigment, wherein the foaming capsule is a core-shell structured foaming capsule composed of a polymer shell and a foaming agent core.

[0011] According to another aspect of the present invention, a coated steel sheet with excellent heat insulation and sound absorption properties is provided, comprising: a steel sheet; a pretreatment layer formed on at least one side of the steel sheet; and a coating formed on the pretreatment layer, wherein the coating comprises the heat insulation and sound absorption coating composition of the present invention.

[0012] According to another aspect of the present invention, a method for manufacturing a coated steel sheet with excellent heat insulation and sound absorption properties is provided, comprising: a step of forming a pretreatment layer on the steel sheet; and a step of forming a coating on the pretreatment layer, wherein the step of forming the coating comprises: a step of applying the heat insulation and sound absorption coating composition of the present invention; and a step of drying the coated composition.

[0013] (III) Beneficial Effects The coating film formed by the coating composition of the present invention contains heat-insulating pigments, thereby blocking external heat by radiating infrared rays from sunlight, and achieving noise reduction through the micropores generated by foaming, thus minimizing heat transfer. Furthermore, it also provides insulation to prevent internal heat loss to the outside. Through these effects, energy efficiency in cooling / heating can be improved, contributing to energy conservation, while also achieving noise reduction against external impacts. In addition, the coating film formed by the present invention exhibits high solar reflectivity and very low thermal conductivity, while also possessing excellent noise characteristics, effectively providing steel plates requiring the physical properties described above. Attached Figure Description

[0014] Figure 1 This illustrates the heat insulation principle of the coating composition of the present invention, and shows the effects of solar absorption and reflection blocking.

[0015] Figure 2 This is a schematic diagram illustrating the thermal insulation performance evaluation testing machine. Best practice

[0016] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention can be modified in many other ways, and the scope of the present invention is not limited to the embodiments described below.

[0017] This invention relates to a coating composition with excellent heat insulation and noise reduction effects and a surface-treated steel sheet using the same. More specifically, it relates to a technique that imparts heat insulation function to a steel sheet by utilizing a coating composition containing heat-insulating / heat-reflecting pigments and a foaming agent, thereby providing a surface-treated steel sheet with excellent heat insulation, heat reflection and noise reduction properties, while also being processable and corrosion-resistant.

[0018] The heat insulation and sound absorption coating composition of the present invention comprises: polyvinyl chloride resin; plasticizer; foaming capsule; and ceramic-based heat insulation pigment, wherein the foaming capsule is a core-shell structured foaming capsule composed of a polymer shell and a foaming agent core.

[0019] The molecular weight of the polyvinyl chloride resin of the present invention is preferably 5,000 to 8,000. When the molecular weight is lower than the above range, there is a problem of poor processability. When the molecular weight is higher than the above range, there is a problem of difficulty in controlling the coating thickness due to high viscosity.

[0020] Hereinafter, the content of the components constituting the composition of the present invention is described based on the weight ratio of polyvinyl chloride resin. However, when based on the weight of the total coating composition, the content of polyvinyl chloride resin is preferably in the range of 40% to 70% by weight, but its content can be adjusted according to workability and coating thickness. When the content of polyvinyl chloride resin is less than 40% by weight, the resin content is insufficient, which may lead to insufficient heat insulation and noise reduction performance. On the other hand, when the content of polyvinyl chloride resin is greater than 70% by weight, the viscosity is too high, which may be detrimental to workability.

[0021] Based on 100 parts by weight of polyvinyl chloride resin, the coating composition comprises 5 to 30 parts by weight of plasticizer, 0.5 to 10 parts by weight of foaming capsules, and 5 to 20 parts by weight of heat-insulating pigment. For example, based on 100 parts by weight of polyvinyl chloride resin, it comprises 15 to 25 parts by weight of plasticizer, 1 to 5 parts by weight of foaming capsules, and 6 to 15 parts by weight of heat-insulating pigment.

[0022] Plasticizers are included in polyvinyl chloride resin to improve the flexibility and workability of the solution. When the content of the plasticizer is below the range of the present invention, the viscosity of the solution containing polyvinyl chloride resin is too high, resulting in poor workability. On the other hand, when the content of the plasticizer is above the range of the present invention, the viscosity is too low and the coating film is too soft, which may make it difficult to achieve the desired properties.

[0023] In addition, when the content of the foamed capsule is below the range of the present invention, the formation of pores is not obvious, which may lead to insufficient heat insulation and sound absorption performance. When the content of the foamed capsule is above the range of the present invention, the formation of pores may lead to a decrease in heat insulation and sound absorption performance.

[0024] Furthermore, when the content of the heat-insulating pigment is below the range of the present invention, the heat insulation performance may be insufficient; when the content of the heat-insulating pigment is above the range of the present invention, there is a problem of poor surface quality due to pigment precipitation or agglomeration.

[0025] The plasticizer that can be used in this invention may be at least one selected from di(2-ethylhexyl) adipate (DEHA), dimethyl adipate (DMAD), monomethyl adipate (MMAD), dioctyl adipate (DOA), dibutyl sebacate (DBS), dibutyl maleate (DBM), diisobutyl maleate (DIBM), and trimethylpentanyldiisobutylate.

[0026] In addition, the polymer shell of the foamed capsule of the present invention may be composed of at least one olefin resin selected from polypropylene and polyethylene, for example, using polypropylene.

[0027] The foaming agent core of the foaming capsule of the present invention may contain at least one foaming agent selected from azodicarbonamide, carboxylated azodicarbonamide, benzenesulfonyl hydrazine, dinitrosopentamethylenetetramine, toluenesulfonyl hydrazine, azobisisobutyronitrile, barium azodicarbonate, sodium bicarbonate and p,p'-oxobis(benzenesulfonyl hydrazine).

[0028] The core-shell powder form of the foamed capsule of the present invention has the advantage of forming closed pores that maintain a spherical shape during foaming.

[0029] In addition, the average particle size of the foamed capsule is preferably between 5 μm and 20 μm. When the average particle size of the foamed capsule is less than 5 μm, the size of the closed pores after foaming is too small, which may make it difficult to obtain the porosity effect. On the other hand, when the average particle size of the foamed capsule is greater than 20 μm, the size of the closed pores after foaming is too large, which may cause the surface quality of the coating to deteriorate or the physical properties of the coating to decrease during processing.

[0030] The pigments used in this invention are preferably ceramic-based heat-insulating pigments, such as at least one selected from Fe2O3 / mica (MICA), TiO2 / mica, TiO2-Cr2O3, montmorillonite, illite, zeolite, SiO2, and Al2O3. Furthermore, the use of the " / " designation, for example, Fe2O3 / mica, refers to a form in which Fe2O3 metal oxide is coated onto mica.

[0031] The heat-insulating pigment of the present invention is not particularly limited in size, but preferably the average diameter of the heat-insulating pigment can be in the range of 5 μm to 20 μm. When the average diameter is less than 5 μm, the viscosity of the solution may increase. On the other hand, when the average diameter is greater than 20 μm, the stability of the solution may decrease due to precipitation after dispersion.

[0032] Furthermore, the heat insulation and sound absorption coating composition of the present invention, based on 100 parts by weight of polyvinyl chloride resin, may further contain 5 to 20 parts by weight of solvent, wherein the solvent may be at least one selected from solvent naphtha, toluene, xylene, isopropanol, cellosol, acetic acid cellosol, and butyl cellosol.

[0033] In addition, according to another aspect of the present invention, a steel plate with excellent heat insulation and sound absorption properties utilizing the coating composition of the present invention is provided.

[0034] More specifically, the steel plate with excellent heat insulation and sound absorption properties of the present invention comprises: a steel plate; a pretreatment layer formed on at least one side of the steel plate; and a coating formed on the pretreatment layer, wherein the coating comprises the heat insulation and sound absorption coating composition of the present invention described above.

[0035] The steel plate may be selected from carbon steel, aluminum steel, aluminum alloy steel, stainless steel, copper steel, galvanized steel plate and zinc-containing binary or ternary alloy coated steel plate, preferably selected from cold-rolled steel plate, hot-rolled steel plate, galvanized steel plate, zinc alloy coated steel plate, stainless steel plate and aluminum steel plate.

[0036] The coated steel sheet of the present invention may include a pretreatment layer formed on at least one side of the steel sheet. The pretreatment layer may be applied to enhance the corrosion resistance of the metal sheet and the adhesion of the metal sheet to the heat insulation and noise reduction coating. The pretreatment layer may be treated with a phosphate film, chromate or non-chromate chemical conversion film, and preferably it may be a chromium-free pretreatment layer.

[0037] According to another aspect of the present invention, a method for manufacturing a steel plate with excellent heat insulation and sound absorption properties utilizing the coating composition of the present invention is provided.

[0038] More specifically, the method for manufacturing a steel plate with excellent heat insulation and sound absorption properties according to the present invention includes: a step of forming a pretreatment layer on the steel plate; and a step of forming a coating on the pretreatment layer, wherein the step of forming the coating includes: a step of applying the above-described heat insulation and sound absorption coating composition of the present invention; and a step of drying the coated composition.

[0039] The step of forming the pretreatment layer can be performed with a thickness of 0.1 μm to 2 μm. When the thickness of the pretreatment layer is less than 0.1 μm, the adhesion to the coating of the present invention may be insufficient. When the thickness of the pretreatment layer is greater than 2 μm, there is a problem of reduced economic efficiency due to increased manufacturing costs.

[0040] In addition, the coating composition can be applied at a thickness of 40 μm to 200 μm. When the thickness is less than 40 μm, the performance of the coating film formed by the coating composition may not be fully realized. When the thickness is greater than 200 μm, there is a problem of reduced economic efficiency due to increased manufacturing costs.

[0041] The drying step of the coating composition can be carried out at a temperature of 195°C to 235°C, for example, at 200°C to 225°C. During this drying step, foamed pores in the coating composition of the present invention can be formed from the foamed capsules. More specifically, when drying and curing are carried out under the temperature conditions of the present invention, the foamed capsules foam to form pores. When the drying and curing temperature is below 195°C, the degree of reaction of the foamed capsules is weak, resulting in a smaller average particle size of the foamed pores or a reduction in the number of foamed pores, making it difficult to obtain the sound insulation and heat insulation effects of the pores. On the other hand, when the drying and curing temperature is above 235°C, the polymer film surrounding the foamed capsules may melt due to the high temperature, causing the foamed pores to be destroyed, making it difficult to achieve the desired properties.

[0042] The coating composition provided by this invention has a fast drying time, making it suitable for coating processes on steel plates. It also provides a highly durable surface-treated steel plate that can maintain excellent thermal insulation, heat insulation properties, and noise reduction characteristics over a long period. Therefore, for example, roof structures made from steel plates manufactured according to this invention can suppress the absorption of solar heat and temperature rise, and can also reduce external impact noise.

[0043] The present invention will now be described in more detail through specific embodiments. These embodiments are merely examples to aid in understanding the invention, and the scope of the invention is not limited thereto. Detailed Implementation

[0044] Example 1. Preparation of coating compositions Example 1 100g of polyvinyl chloride resin as a polymer resin, 20g of bis(2-propylheptayl) phthalate (DPHP) as a plasticizer, 2g of foaming capsules, 4g of heat-insulating pigment Fe2O3-mica, 4g of montmorillonite, and 5g of light gray pigment (Stuc-O-Flex 312 pigment) as an additive, along with 10g of solvent (solvent naphtha), were added, and then stirred to prepare a coating composition. In this case, the foaming capsules used were foaming capsules with an average particle size of 10μm to 15μm, containing an azodicarbonamide foaming agent within a polypropylene shell.

[0045] Example 2 The coating composition was prepared by the same method as in Example 1, except that the amount of foaming capsules in the coating composition of Example 1 was changed to 4g.

[0046] Comparative Example 1 The coating composition was prepared by the same method as in Example 1, except that the heat-insulating pigment was removed from the coating composition of Example 1.

[0047] Comparative Example 2 The coating composition was prepared by the same method as in Example 1, except that the foaming capsules were removed from the coating composition of Example 1.

[0048] 2. Manufacturing of coated steel plates Preparation Example 1 The coating composition of Example 1 prepared in section 1 was applied to a 20×20cm galvanized steel sheet. Pretreatment with a chromium-free solution (NCF-200P from DAE HAN PARKERIZING CO., LTD.) to a thickness of approximately 1 μm was performed, followed by application of the coating composition to one side at a thickness of 50 μm. The coating was applied using a rod coating method with a #25 nozzle, and dried at the actual production line manufacturing temperature of 224°C for 30 seconds. After drying, the coating film expanded approximately three times its original size due to foaming.

[0049] Preparation Example 2 The coated metal sheet was prepared by the same method as in Preparation Example 1, except that the coating composition of Example 1 was applied to a thickness of 100 μm.

[0050] Preparation Example 3 The coated metal sheet was prepared by the same method as in Preparation Example 1, except that the coating composition of Example 1 was applied to a thickness of 150 μm.

[0051] Preparation Example 4 The coated metal sheet was prepared by the same method as in Preparation Example 1, except that the coating composition of Example 2 was used.

[0052] Comparative Preparation Example 1 The coated metal sheet was prepared by the same method as in Preparation Example 1, except that the coating composition of Comparative Example 1 was used.

[0053] Comparative Preparation Example 2 The coated metal sheet was prepared using the same method as in Preparation Example 1, except that the coating composition of Comparative Example 2 was used. No coating swelling occurred because the foaming capsules were removed.

[0054] Comparative Preparation Example 3 The coated metal sheet was prepared using the same method as in Preparation Example 1, except that the coating composition of Example 1 was dried at 190°C for 30 seconds. Due to insufficient foaming temperature during drying, foaming was inadequate.

[0055] Comparative Preparation Example 4 The coated metal sheet was prepared by the same method as in Preparation Example 1, except that the coating composition described in Example 1 was dried at 240°C for 30 seconds.

[0056] Comparative Preparation Example 5 The coated metal sheet was prepared by the same method as in Preparation Example 1, except that the coating composition of Example 1 was applied to a thickness of 30 μm.

[0057] Comparative Preparation Example 6 The existing commercially available 20×20cm standard color-coated steel sheet (POSCOSTEELEON product) was used. This color-coated steel sheet consists of a 1μm pretreatment layer, a 5μm polyester resin primer layer, and a 20μm polyester resin color coating layer.

[0058] 3. Evaluation Criteria for the Characteristics of Coated Metal Sheets (1) Salt spray test The salt spray test is a method for judging corrosion resistance by using a razor blade to make X-shaped scratches of 5×10cm size on the surface of the sample in the groove until the substrate is exposed. The sample is sprayed with 5% salt water at 35°C. After 480 hours, the surface area of ​​the corroded part of the entire surface area of ​​the coated metal plate is measured. For the scratched part, the expansion and peeling length of the coating film are measured with the scratch line as the center to evaluate the degree of corrosion.

[0059] [◎]: After 480 hours, less than 5% of the entire surface area of ​​the coated metal sheet is corroded or scratched, with a peeling of less than 1mm. [○]: After 480 hours, more than 5% of the entire surface area of ​​the coated metal plate is corroded or scratched and peels off by less than 2mm. [Δ]: After 480 hours, more than 5% of the entire surface area of ​​the coated metal sheet is corroded or scratched and peeled off by more than 3mm. (2) Evaluation of thermal insulation performance Thermal insulation performance evaluation, such as Figure 2 The diagram illustrates a measuring apparatus for fixing either the prepared or comparative prepared sample on the roof of a polystyrene foam house. A 500-watt incandescent light bulb is mounted above the apparatus. The sample is placed on top of a square polystyrene foam box with the coating facing the part receiving heat from the incandescent bulb. The internal temperature is measured after the bulb is lit for one hour. The internal temperature is compared to that of a 0.6T untreated galvanized steel sheet after one hour of lighting.

[0060] [◎]: The temperature difference between the internal temperature of the reference material and the internal temperature of the sample is greater than 5℃. [○]: The temperature difference between the internal temperature of the reference material and the internal temperature of the sample is greater than 2℃ and less than 4℃. [Δ]: The temperature difference between the internal temperature of the reference material and the internal temperature of the sample is less than 2℃. (3) Evaluation of Solar Reflectance Index The solar reflectance index is a test method based on ASTM E1980. It is an indicator of a material's ability to reflect solar energy back to the atmosphere. The higher the solar reflectance index, the more external heat is reflected, which indicates excellent heat insulation performance. Therefore, the solar reflectance index of the sample was evaluated.

[0061] [◎]: Solar reflectance index is 75 or above. [○]: Solar reflectance index is 50 or higher and less than 75. [Δ]: Solar reflectance index is less than 50. (4) Evaluation of noise reduction performance To evaluate the noise reduction performance, the impact noise of the coated surface was measured by dropping a 5g steel ball from a height of 150mm. Each noise measurement was repeated three times, and the average value was used for analysis. For comparison, the average impact noise of 86dB from a 0.6T untreated galvanized steel sheet without any coating was used as the benchmark.

[0062] [◎]: Noise reduction of 10dB or more [○]: Noise reduction of 5dB or more but less than 10dB [Δ]: Noise reduction less than 5dB (5) Bending test Peeling or cracking of the coating at curved sections is evaluated using a 3T processability assessment at a 180° angle.

[0063] [◎]: No peeling or cracks [○]: No peeling, but microcracks have appeared. [Δ]: Delamination and cracking occur. [Table 1] Evaluation results of the characteristics of coated metal sheets The embodiments of the present invention have been described in detail above, but the scope of the present invention is not limited thereto. Various modifications and variations can be made without departing from the technical concept of the present invention as set forth in the claims, which will be obvious to those skilled in the art.

Claims

1. A coating composition for heat insulation and sound absorption, comprising: polyvinyl chloride resin; plasticizer; foaming capsule; and ceramic-based heat-insulating pigment. in, The foamed capsule is a core-shell structured foamed capsule consisting of a polymer shell and a foaming agent core.

2. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, Based on 100 parts by weight of polyvinyl chloride resin, the coating composition comprises 5 to 30 parts by weight of plasticizer, 0.5 to 10 parts by weight of foaming capsules, and 5 to 20 parts by weight of heat-insulating pigment.

3. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, The plasticizer is selected from at least one of di(2-ethylhexyl) adipate (DEHA), dimethyl adipate (DMAD), monomethyl adipate (MMAD), dioctyl adipate (DOA), dibutyl sebacate (DBS), dibutyl maleate (DBM), diisobutyl maleate (DIBM), and trimethylpentyl diisobutyrate.

4. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, The polymer shell of the foamed capsule is composed of at least one olefin resin selected from polypropylene and polyethylene.

5. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, The foaming agent core of the foaming capsule contains at least one foaming agent selected from azodicarbonamide, carboxyazodicarbonamide, benzenesulfonyl hydrazine, dinitrosopentamethylenetetramine, toluenesulfonyl hydrazine, azobisisobutyronitrile, barium azodicarbonate, sodium bicarbonate, and p,p'-oxobis(benzenesulfonyl hydrazine).

6. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, The average particle size of the foamed capsules is 5 μm to 20 μm.

7. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, The ceramic-based heat-insulating pigment is selected from at least one of Fe2O3 / mica, TiO2 / mica, TiO2-Cr2O3, montmorillonite, illite, zeolite, SiO2, and Al2O3.

8. The heat-insulating and sound-absorbing coating composition according to claim 1, wherein, Based on 100 parts by weight of polyvinyl chloride resin, it further contains 5 to 20 parts by weight of solvent.

9. The heat-insulating and sound-absorbing coating composition according to claim 8, wherein, The solvent is selected from at least one of the following: naphtha, toluene, xylene, isopropanol, cellosol, acetic acid cellosol, and butyl cellosol.

10. A coated steel sheet with excellent heat insulation and sound absorption properties, comprising: Steel plate; A pretreatment layer is formed on at least one side of the steel plate; and a coating formed on the pretreatment layer, The coating comprises the heat-insulating and sound-absorbing coating composition according to any one of claims 1 to 9.

11. The coated steel sheet with excellent heat insulation and sound absorption properties according to claim 10, wherein, The steel plate is selected from carbon steel, aluminum steel, aluminum alloy steel, stainless steel, copper steel, galvanized steel plate and zinc-containing binary or ternary alloy coated steel plate.

12. The coated steel sheet with excellent heat insulation and sound absorption properties according to claim 10, wherein, The pretreatment layer is treated with a phosphating film, chromate or non-chromate chemical conversion film.

13. A method for manufacturing a coated steel sheet with excellent heat insulation and sound absorption properties, comprising: The step of forming a pretreatment layer on a steel plate; and the step of forming a coating on the pretreatment layer, The step of forming the coating includes: applying the heat-insulating and sound-absorbing coating composition according to any one of claims 1 to 9; and drying the applied composition.

14. The method for manufacturing a coated steel sheet with excellent heat insulation and sound absorption properties according to claim 13, wherein, The step of forming the pretreatment layer is performed with a thickness of 0.1 μm to 2 μm.

15. The method for manufacturing a coated steel sheet with excellent heat insulation and sound absorption properties according to claim 13, wherein, The coating composition is applied at a thickness of 40 μm to 200 μm.

16. The method for manufacturing a coated steel sheet with excellent heat insulation and sound absorption properties according to claim 13, wherein, The drying process of the coating composition is carried out at a temperature of 195°C to 235°C.

Images