Pre-coated metal color sheet and manufacturing method of pre-coated metal color sheet

Abstract

The present invention relates to a PCM color steel sheet and a method for manufacturing the same, wherein the PCM color steel sheet comprises a base steel sheet (1), a molten plating layer (2) formed on the upper surface of the base steel sheet (1), a pretreatment layer (3) formed on the upper surface of the molten plating layer (2), a primer coating layer (4) formed on the upper surface of the pretreatment layer (3), an intermediate coating layer (5) formed on the upper surface of the primer coating layer (4), and a top coating layer (6) formed on the upper surface of the intermediate coating layer (5). In the PCM color steel sheet, a flame retardant is added to the primer paint forming the primer coating layer (4) and the primer paint forming the intermediate coating layer (5), and the flame retardant is characterized by being formed by mixing one or more of a hydroxide, boron-based, tin-based, and antimony-based flame retardant.

Description

Technology Field

[0001] The present invention relates to a PCM color steel sheet and a method for manufacturing the same, and more specifically, to a PCM color steel sheet and a method for manufacturing the same that can be used as an interior material for ships by improving heat resistance to satisfy the performance standards of the fire test procedure established by the International Maritime Organization. Background Technology

[0002] Steel plate painting methods include the post-coating method, in which the steel plate is painted after forming and processing, and the pre-coating method, in which the steel plate is painted before forming and processing.

[0003] Steel plates coated using the above-mentioned pre-coating method are commonly referred to as PCM (Pre-Coated Metal) steel plates or PCM color steel plates, and the paint used therein is called PCM paint.

[0004] PCM steel sheets coated with such PCM paint undergo a separate processing step after coating.

[0005] Accordingly, PCM paints must satisfy conditions such as excellent processability, film hardness, adhesion, weather resistance, corrosion resistance, and curability.

[0006] The aforementioned PCM color steel sheets are currently used for interior and exterior construction and home appliances, and their applications are becoming increasingly diversified through continuous technological development.

[0007] Recently, there has been a new demand for using PCM color steel sheets for ship interior materials where fire safety performance is critical.

[0008] In order to use the above-mentioned PCM steel plate as ship interior material, it must satisfy the test methods and performance standards of the Fire Test Procedure (FTP Code) established by the International Maritime Organization.

[0009] However, there is a problem in that the PCM color steel sheets currently being manufactured have difficulty satisfying the above performance standards. The problem to be solved

[0010] The present invention aims to solve the problems of the aforementioned prior art by providing a PCM color steel sheet that can satisfy the requirements for ship interior materials by significantly improving heat resistance while maintaining the basic physical properties and appearance quality of existing color steel sheets.

[0011] Another objective of the present invention is to improve fire safety performance while ensuring corrosion resistance, weather resistance, and moisture resistance required for PCM color steel sheets are equivalent to those of existing color steel sheets. means of solving the problem

[0012] To achieve the above-mentioned purpose, the PCM color steel sheet according to the present invention comprises a base steel sheet, a hot-dip galvanizing layer formed on the upper surface of the base steel sheet, a pretreatment layer formed on the upper surface of the hot-dip galvanizing layer, a primer coating layer formed on the upper surface of the pretreatment layer, an intermediate coating layer formed on the upper surface of the primer coating layer, and a top coating layer formed on the upper surface of the intermediate coating layer, wherein a flame retardant is added to the primer paint forming the primer coating layer and the primer paint forming the intermediate coating layer, and the flame retardant is formed by mixing one or more of a hydroxide, boron-based, tin-based, and antimony-based flame retardant.

[0013] In addition, the above-mentioned molten plating layer is characterized by being composed of any one of a zinc plating layer, an aluminum plating layer, a zinc-aluminum alloy plating layer, or a zinc-aluminum-magnesium ternary alloy plating layer.

[0014] In addition, the above pretreatment layer is characterized by being formed as any one of a phosphate film layer, a chromate chemical conversion film layer, or a non-chromate chemical conversion film layer.

[0015] In addition, the above primer layer is characterized by being formed by a primer paint comprising, based on the total composition, 40 to 50 weight% polyester resin, 30 to 40 weight% anti-corrosion pigment, 10 to 15 weight% flame retardant, 1 to 5 weight% melamine curing agent, and 1 to 5 weight% additive.

[0016] In addition, the polyester resin included in the above primer paint is characterized by having a number average molecular weight of 10,000 to 15,000, a glass transition temperature of 15 to 25°C, and a solid content of 50 to 60 weight%.

[0017] In addition, the above intermediate coating layer is characterized by being formed by an intermediate paint comprising, based on the total composition, 40 to 50 weight% polyester resin, 20 to 30 weight% pigment, 15 to 20 weight% flame retardant, 3 to 8 weight% melamine curing agent, 5 to 10 weight% solvent, and 1 to 5 weight% additive.

[0018] In addition, the polyester resin included in the above intermediate paint is characterized by containing a phosphorus (P) component and having a number average molecular weight of 20,000 to 30,000.

[0019] In addition, the topcoat layer is formed by a topcoat paint comprising, based on the total composition, 70 to 80 weight% of a silicone polyester mixed resin, 10 to 15 weight% of a solvent, 5 to 10 weight% of a melamine curing agent, and 1 to 5 weight% of an additive, and is characterized in that the silicone component in the silicone polyester mixed resin is 70 to 80 weight%.

[0020] And the method for manufacturing a PCM color steel sheet according to the present invention comprises: (a) a step of forming a molten plating layer on at least one surface of a base steel sheet (S10); (b) a step of forming a pretreatment layer on the upper surface of the molten plating layer (S20); (c) a step of forming a primer coating layer on the upper surface of the pretreatment layer (S30); and (d) a step of forming an intermediate coating layer on the upper surface of the primer coating layer (S40). (e) A method for manufacturing a PCM color steel sheet comprising the step (S50) of forming a top coat layer on the upper surface of the intermediate coat layer, wherein in step S30, a flame retardant mixed with one or more of a hydroxide, boron-based, tin-based, and antimony-based flame retardant is added to the primer paint in an amount of 10 to 15 weight%, and in step S40, a flame retardant mixed with one or more of a hydroxide, boron-based, tin-based, and antimony-based flame retardant is added to the intermediate coat paint in an amount of 15 to 20 weight%.

[0021] In addition, in the above S20 step, the pretreatment layer is characterized by being applied in an amount of 30 to 80 mg / m².

[0022] In addition, in the above S30 step, the undercoat layer is formed with a film thickness of 3 to 10 μm by a roll coater and is characterized by being dried at PMT 180 to 220°C.

[0023] In addition, the intermediate coating layer in step S40 and the top coating layer in step S50 are formed with a film thickness of 10 to 30 μm by a roller coater and are characterized by being dried at PMT 224 to 241°C. Effects of the invention

[0024] According to the present invention, it is possible to provide a PCM color steel sheet with superior heat resistance compared to existing ones, while satisfying physical properties such as excellent processability, chemical resistance, corrosion resistance, weather resistance, paint adhesion, and film hardness required for interior and exterior building materials.

[0025] In addition, it has the effect of improving fire safety performance while ensuring corrosion resistance, weather resistance, and moisture resistance required for PCM color steel sheets at a level equivalent to existing color steel sheets.

[0026] In particular, by satisfying the test methods and performance standards of the Fire Test Procedure (FTP Code) established by the International Maritime Organization, PCM color steel sheets can be used for ship interior materials where fire safety performance is critical. Brief explanation of the drawing

[0027] FIG. 1 is a schematic cross-sectional view of a PCM color steel sheet according to the present invention. Specific details for implementing the invention

[0028] Hereinafter, preferred embodiments of the PCM color steel sheet and the method for manufacturing the same according to the present invention will be described in detail.

[0029] First, the PCM color steel plate according to the present invention comprises, as shown in FIG. 1, a base steel plate (1), a molten plating layer (2) formed on the upper surface of the base steel plate (1), a pretreatment layer (3) formed on the upper surface of the molten plating layer (2), a primer coating layer (4) formed on the upper surface of the pretreatment layer (3), an intermediate coating layer (5) formed on the upper surface of the primer coating layer (4), and a top coating layer (6) formed on the upper surface of the intermediate coating layer (5). In this PCM color steel plate, a flame retardant is added to the primer paint forming the primer coating layer (4) and to the primer paint forming the intermediate coating layer (5).

[0030] Here, the flame retardant is formed by mixing one or more of a hydroxide, boron-based, tin-based, or antimony-based flame retardant.

[0031] The above molten plating layer (2) is formed on the upper surface of the above steel plate (1) and may be any one of a zinc plating layer, an aluminum plating layer, a zinc-aluminum alloy plating layer, or a zinc-aluminum-magnesium ternary alloy plating layer.

[0032] And on the upper surface of the above molten plating layer (2), a pretreatment layer (3) is formed to increase the adhesion between the base steel plate (1) and the undercoat layer (4) and to improve the corrosion resistance of the product.

[0033] The above pretreatment layer (3) is formed as one of a phosphate film layer, a chromate chemical film layer, or a non-chromate chemical film layer, and is applied in an amount of 30 to 80 mg / m².

[0034] And the above primer layer (4) is formed by a primer paint comprising, based on the total composition, 40 to 50 weight% polyester resin, 30 to 40 weight% anti-corrosion pigment, 10 to 15 weight% flame retardant, 1 to 5 weight% melamine curing agent, and 1 to 5 weight% additive.

[0035] The polyester resin included in the above primer paint preferably has a number average molecular weight of 10,000 to 15,000, a glass transition temperature of 15 to 25°C, and a solid content of 50 to 60 weight%.

[0036] The above undercoat layer (4) acts as an intermediate binder between the base steel plate (1) and the intermediate coat layer (5) to improve the adhesion of the coating film and contributes to improving corrosion resistance through the addition of anti-corrosion pigment.

[0037] For the above-mentioned anti-corrosion pigment, it is preferable to use calcium-based or zinc-based anti-corrosion pigments instead of strontium chromate, an environmentally regulated hazardous substance previously used in existing building materials.

[0038] The intermediate coating layer (5) formed on the upper surface of the above undercoat layer (4) is formed by an intermediate coating paint comprising, based on the total composition, 40 to 50 weight% polyester resin, 20 to 30 weight% pigment, 15 to 20 weight% flame retardant, 3 to 8 weight% melamine curing agent, 5 to 10 weight% solvent, and 1 to 5 weight% additive.

[0039] Here, the polyester resin included in the above intermediate paint preferably contains phosphorus (P) and has a number average molecular weight of 20,000 to 30,000.

[0040] The flame retardant included in the above intermediate paint is an inorganic flame retardant such as a hydroxide, boron-based, tin-based, or antimony-based agent, used alone or in an appropriate mixture.

[0041] If the content of the above flame retardant is added at less than 15%, the heat resistance performance intended for the present invention is not sufficiently exhibited, and if the content exceeds 20%, the adhesion and flexibility of the coating film are reduced.

[0042] Therefore, it is preferable to add the above flame retardant in an amount of 15 to 20 weight percent relative to the total composition of the intermediate paint.

[0043] It is preferable to use only inorganic pigments with excellent heat resistance and weather resistance as pigments included in the above intermediate paint, and oxides, hydroxides, sulfides, silicates, sulfates, carbonates, carbon black, etc. are appropriately mixed and used to match the color to be achieved.

[0044] The above intermediate coating layer (5) serves to improve the hiding power and give color to the product, and contributes to improving the overall physical properties of the PCM steel sheet, such as processability, corrosion resistance, and weather resistance.

[0045] The above topcoat layer (6) is formed by a topcoat paint comprising, based on the total composition, 70 to 80 weight% of silicone polyester mixed resin, 10 to 15 weight% of solvent, 5 to 10 weight% of melamine curing agent, and 1 to 5 weight% of additive.

[0046] The following describes in more detail each component of the PCM paint composition that forms the top coating layer (5).

[0047] Suzy

[0048] The resin of the topcoat paint forming the topcoat layer (6) is a silicone polyester mixed resin.

[0049] Here, it is preferable that the silicone component in the silicone polyester mixed resin be 70 to 80 weight percent.

[0050] If the content of the above silicone component is less than 70%, the heat resistance of the resin, which makes up most of the paint, becomes relatively low, and the target heat resistance is not satisfied.

[0051] In addition, if the silicon content exceeds 80%, processability and chemical resistance decrease, making it difficult to satisfy the basic quality required for PCM color steel sheets.

[0052] Hardener

[0053] It is preferable to use a melamine-type resin as a curing agent.

[0054] Since the above melamine resin reacts with the OH groups of the polyester resin to form cross-links, if the content of the melamine cured resin is less than 5%, the curing density is lowered, and the quality of solvent resistance, chemical resistance, durability, etc. is reduced.

[0055] In addition, if the content of melamine cured resin exceeds 10%, the dense bonding between the OH groups and the remaining melamine resin after reaction increases, leading to a problem of reduced processing quality.

[0056] In addition, as the heat resistance decreases as the content of the above melamine resin increases, the content is not to exceed 10%.

[0057] The above-mentioned hardener is also added to primers and intermediate paints for the same purpose.

[0058] Solvent

[0059] Solvents serve to lower the viscosity of paint by diluting it to make it suitable for painting when the paint lacks fluidity or has high viscosity at room temperature, making it difficult to apply.

[0060] It is preferable to use an organic solvent that can disperse resin and other components as the solvent added to the paint composition of the present invention.

[0061] The above organic solvents include aliphatic hydrocarbon-based, aromatic hydrocarbon-based, ester-based, ketone-based, alcohol-based, and ether-based solvents, used alone or in an appropriate mixture.

[0062] It is preferable that the solvent included in the topcoat paint be contained in an amount of 10 to 15 weight percent relative to the total composition of the topcoat paint.

[0063] The above solvent is also added to primer and intermediate paints for the same purpose.

[0064] <Additives>

[0065] Additives play an auxiliary role in ensuring that the paint fully performs its necessary functions at each stage, from manufacturing to drying and maintaining durability.

[0066] Generally, additives are classified according to their function and application, but since they may also vary depending on the type of paint, additives suitable for each paint must be selected and used.

[0067] To improve workability and prevent the paint from adhering to the surface, surface tension modifiers, rheology modifiers, and curing reaction catalysts are used, and leveling agents and defoaming agents are also used as needed.

[0068] In addition, to improve film performance or impart functionality after film formation, matting agents, preservatives, surface tension modifiers, UV absorbers, and light stabilizers are used.

[0069] In addition, pigment settling inhibitors, film-forming agents, and thickening inhibitors are used during the storage and transportation of paints.

[0070] The above additive is also added to primer and intermediate paints for the same purpose.

[0071] Next, a method for manufacturing a PCM color steel sheet according to the present invention will be described.

[0072] A method for manufacturing a PCM color steel sheet according to the present invention comprises: (a) a step of forming a molten plating layer (2) on at least one surface of a base steel sheet (1) (S10); (b) a step of forming a pretreatment layer (3) on the upper surface of the molten plating layer (2) (S20); (c) a step of forming a primer coating layer (4) on the upper surface of the pretreatment layer (3) (S30); (d) a step of forming an intermediate coating layer (5) on the upper surface of the primer coating layer (4) (S40); and (e) a step of forming a top coating layer (6) on the upper surface of the intermediate coating layer (5) (S50).

[0073] Here, in the above S30 step, 10 to 15 weight percent of a flame retardant is added to the primer paint, which is a mixture of one or more of hydroxide, boron-based, tin-based, and antimony-based flame retardants.

[0074] In addition, in the above S40 step, 15 to 20 weight percent of a flame retardant is added to the intermediate paint, which is a mixture of one or more of hydroxide, boron-based, tin-based, and antimony-based flame retardants.

[0075] By the above-described manufacturing method, the heat resistance of PCM color steel sheets is significantly improved, making them suitable for use as ship interior materials where fire safety performance is important.

[0076] And, the above pretreatment layer (3) is preferably applied in an amount of 30 to 80 mg / m² of any one of a phosphate film layer, a chromate chemical film layer, or a non-chromate chemical film layer.

[0077] By the above pretreatment layer (3), the adhesion between the base steel plate (1) and the undercoat layer (3) can be increased, and the corrosion resistance of the product can be improved.

[0078] The above primer coating layer (4) is preferably formed by a primer paint in which the main components are polyester resin and anti-corrosion pigment and a flame retardant is added, and the film thickness is formed to 3 to 10 μm by a roll coater.

[0079] In addition, it is preferable to dry the above primer layer (4) under conditions of PMT 180 to 220℃.

[0080] The above PMT (Peak Metal Temperature) refers to the maximum temperature the material receives during the drying process, and if the drying temperature of the primer layer (4) is less than 180℃, it is not completely dried and the physical properties of the product are degraded.

[0081] In addition, if the above PMT exceeds 220℃, the coating film becomes over-cured, which leads to a problem of reduced adhesion and processability.

[0082] The intermediate coating layer (5) formed on the upper surface of the above undercoat layer (4) provides color and hiding power to the product between the undercoat layer (4) and the topcoat layer (6), and contributes to improving the overall physical properties of the PCM steel sheet, such as processability, corrosion resistance, weather resistance, and chemical resistance.

[0083] The above intermediate coating layer (5) is formed by an intermediate paint comprising, based on the total composition, 40 to 50 weight% polyester resin, 20 to 30 weight% pigment, 15 to 20 weight% flame retardant, 3 to 8 weight% melamine curing agent, 5 to 10 weight% solvent, and 1 to 5 weight% additive.

[0084] The above intermediate coating layer (5) is dried under conditions of PMT 224 to 241℃, and the coating thickness is preferably 10 to 25㎛.

[0085] If the thickness of the above intermediate coating layer (5) is less than 10㎛, color realization and hiding power are reduced, and problems such as corrosion resistance and weather resistance are reduced.

[0086] And if the thickness of the intermediate coating layer (5) exceeds 25㎛, the heat resistance of the PCM steel plate is reduced, making it difficult to achieve the target fire safety performance.

[0087] In some cases, materials with excellent flame retardancy are added to the paint; however, since the paint itself is composed mostly of organic materials, increasing the film thickness leads to an increase in the organic materials constituting the PCM steel plate, which actually makes heat resistance less favorable.

[0088] Therefore, the thickness of the intermediate coating layer (5) is not exceeded 25㎛.

[0089] The top coat layer (6) formed on the upper surface of the intermediate coat layer (5) plays an important role in providing glossiness to the final product and determining the appearance quality.

[0090] In addition, the top coating layer (6) plays a role in determining physical properties such as processability, durability, corrosion resistance, and weather resistance of the final product.

[0091] The topcoat paint forming the topcoat layer (5) preferably comprises, based on the total composition, 70 to 80 weight% of silicone polyester mixed resin, 10 to 15 weight% of solvent, 5 to 10 weight% of melamine curing agent, and 1 to 5 weight% of additive.

[0092] In addition, the film thickness of the top coating layer (6) is 5 to 15 μm, and it is preferable to dry it under conditions of PMT 224 to 241°C.

[0093] If the thickness of the upper coating layer (5) is less than 5㎛, problems such as corrosion resistance and weather resistance will occur.

[0094] And if the thickness of the top coating layer (5) exceeds 15㎛, the coating thickness becomes too thick, and the amount of organic material constituting the PCM steel plate increases, which is disadvantageous for heat resistance.

[0095] Hereinafter, the results of a comparative evaluation of the physical properties of the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet are described.

[0096] Gyeonghwado

[0097] According to the ASTM D5402 test method, the test plate was held horizontally with one hand, and with the other hand, about 4 to 6 pieces of gauze were wrapped around the finger, and an appropriate amount of solvent (METHYL ETHYL KETONE) was applied and the coating surface was rubbed up and down. The test was terminated when the material was exposed, and the number of times up to that point was measured.

[0098] As a result of the hardening degree evaluation, the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed equivalent results.

[0099] Processability

[0100] According to the KS D 3520 bending test method, after preparing the test specimen, 180-degree T-bending was performed using a vise.

[0101] At this time, processability was evaluated by attaching a tape 75 mm long to the processing area using transparent adhesive tape and then peeling it off at a 60-degree angle at a uniform speed between 0.5 and 1 second.

[0102] As a result of the processability evaluation, both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed good results.

[0103] Film Adhesion

[0104] According to the ASTM D3359 test method, the test specimen was cross-cut 100 times at 1mm intervals, placed on an Ericksen tester, and a radius-shaped punch was placed adjacent to it, and then pushed out to 6mm to perform a tape adhesion test on the formed area.

[0105] Both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed excellent results.

[0106] Acid resistance

[0107] According to the KS M ISO 2812-1 test method, the cut surface was completely protected with tape capable of withstanding the reagent and the test period, 5% HCl reagent was placed in a beaker, and the test plate was completely immersed without contact with the beaker. After 24 hours, it was removed, washed with water, dried, and then observed for any abnormalities.

[0108] Both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed good results.

[0109] Alkali resistance

[0110] According to the KS M ISO 2812-1 test method, the cut surface was completely protected with tape capable of withstanding the reagent and the test period, 5% NaOH reagent was placed in a beaker, and the test plate was completely immersed without contact with the beaker. After 24 hours, it was removed, washed with water, dried, and then observed for any abnormalities.

[0111] Both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed good results.

[0112] Pencil Hardness

[0113] According to the KS D 3520 pencil hardness test method, a test plate was fixed to a pencil hardness tester, and the pencil was sharpened so that the tip was smooth and the angle sharpened so that 3 mm of the lead was exposed, and then the pencil was attached to the hardness tester at a 45-degree angle.

[0114] Next, a load of 1 kg was applied to draw a line 5 times with a length of 20 mm or more, and the test area was erased with an eraser and observed visually.

[0115] The PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed equivalent results.

[0116] Corrosion resistance

[0117] According to the ASTM D B1117 test method, the cut surface of the test specimen was sealed with tape and an X-shaped notch was made on the flat surface with a cutter, and after 500 hours, the degree of white rust and blistering on the flat surface of the test specimen was observed.

[0118] Both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed results that meet the standards of construction materials.

[0119] Moisture resistance

[0120] In accordance with ASTM D 2247, the conditions of the wet tester were set to a temperature of 49±1℃ and a relative humidity of 95%, and the test specimen was fixed to a sample holder and maintained for 1000 hours, after which the degree of blistering was observed.

[0121] Both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed results that meet the standards of construction materials.

[0122] Weather resistance

[0123] In accordance with ASTM G 154, it was evaluated using the Q-LAB QUV accelerated weathering tester.

[0124] In particular, using a UV-B (313nm) fluorescent lamp, UV irradiation for 4 hours (60±3℃) and condensation for 4 hours (50±3℃) were repeated, and the color difference value was measured and evaluated compared to a standard sample.

[0125] Both the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet showed results that meet the standards of construction materials.

[0126] Flame Propagation Test

[0127] The flame propagation test is a test to determine combustibility, and the total heat release rate, peak heat release rate, flame propagation speed, and flame propagation distance of the material were measured according to the test method of Part 5 of the FTP Code established by the International Maritime Organization.

[0128] As a result of the evaluation, the conventional PCM color steel sheet met the standard in only one of the three experiments, but the PCM color steel sheet according to the present invention met the standard in all three experiments.

[0129] [Table 1] below shows the experimental results.

[0130] Experimental results of the PCM color steel sheet according to the present invention and the conventional PCM color steel sheet division Conventional PCM color steel sheets PCM color steel sheet according to the present invention film thickness 30㎛ 30㎛ Hardness 50 times 50 times Processability △ △ Internal boiling water ○ ○ Adhesion ◎ ◎ acid resistance Good 24 hours Good 24 hours alkali resistance Good 24 hours Good 24 hours Pencil hardness F F Corrosion resistance 500 hours good 500 hours good moisture resistance 1,000 hours good 1,000 hours good Weather resistance 500 hours good 500 hours good flame propagation △ ◎ △Average, ○Good, ◎Excellent

[0131] As can be seen from [Table 1] above, the PCM color steel sheet according to the present invention has improved heat resistance while maintaining equivalent physical properties compared to conventional PCM color steel sheets.

[0132] The foregoing describes preferred embodiments of the present invention by way of example, and the scope of the present invention is not limited to the specific embodiments described above. Those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the technical concept of the present invention. Explanation of the symbols

[0133] 1: Base steel plate 2: Hot-dip plating layer 3: Pretreatment layer 4: Primer layer 5: Intermediate coating layer 6: Topcoat layer

Claims

Claim 1 In a PCM color steel plate comprising a base steel plate (1), a molten plating layer (2) formed on the upper surface of the base steel plate (1), a pretreatment layer (3) formed on the upper surface of the molten plating layer (2), a primer coating layer (4) formed on the upper surface of the pretreatment layer (3), an intermediate coating layer (5) formed on the upper surface of the primer coating layer (4), and a top coating layer (6) formed on the upper surface of the intermediate coating layer (5), wherein a flame retardant is added to the primer paint forming the primer coating layer (4) and the primer paint forming the intermediate coating layer (5), and the flame retardant is formed by mixing one or more of a hydroxide, boron-based, tin-based, or antimony-based flame retardant, and the primer coating layer (4) comprises, based on the total composition, 40 to 50 weight% polyester resin and 30 to 40% anti-corrosion pigment A PCM color steel sheet formed by a primer containing 10 to 15 weight% of a flame retardant, 1 to 5 weight% of a melamine curing agent, and 1 to 5 weight% of an additive, wherein the polyester resin included in the primer has a number average molecular weight of 10,000 to 15,000, a glass transition temperature of 15 to 25°C, and a solid content of 50 to 60 weight%. Claim 2 A PCM color steel sheet according to claim 1, wherein the molten plating layer (2) is composed of any one of a zinc plating layer, an aluminum plating layer, a zinc-aluminum alloy plating layer, and a zinc-aluminum-magnesium ternary alloy plating layer. Claim 3 In claim 1, the PCM color steel sheet is characterized in that the pretreatment layer (3) is formed as any one of a phosphate coating layer, a chromate conversion coating layer, and a non-chromate conversion coating layer. Claim 4 delete Claim 5 delete Claim 6 In claim 1, the intermediate coating layer (5) is formed by an intermediate coating paint comprising, based on the total composition, 40 to 50 weight% polyester resin, 20 to 30 weight% pigment, 15 to 20 weight% flame retardant, 3 to 8 weight% melamine curing agent, 5 to 10 weight% solvent, and 1 to 5 weight% additive, characterized in that it is a PCM color steel sheet. Claim 7 In claim 6, the polyester resin included in the intermediate paint is characterized by containing a phosphorus (P) component and having a number average molecular weight of 20,000 to 30,000. Claim 8 In claim 1, the topcoat layer (6) is formed by a topcoat paint comprising, based on the total composition, 70 to 80 weight% of a silicone polyester mixed resin, 10 to 15 weight% of a solvent, 5 to 10 weight% of a melamine curing agent, and 1 to 5 weight% of an additive, and the silicone component in the silicone polyester mixed resin is 70 to 80 weight%, characterized in that the PCM color steel sheet. Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 delete

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