KR20020091603A - Colored steel sheet with single side embossed - Google Patents

Abstract

PURPOSE: A colored steel sheet with single side embossed is provided which obtains three-dimensional beautiful external appearance, solves problems of environmental regulation and shortens processing process using the steel sheet with single side embossed as a material processed, and a manufacturing method of the same is provided. CONSTITUTION: In a colored steel sheet with single side embossed in which a chromate layer is formed on a base steel sheet with single side embossed, a polyester based primer having high forming workability is formed on the chromate layer, and a resin composition comprising a principal resin of polyester resin, a crosslinking agent of melamine resin, curing promoter, other additives and solvent is coated on the polyester based primer as a top coat, the colored steel sheet with single side embossed is characterized in that the polyester resin is a modified oil free polyester compound prepared by reacting oil free polyester having number average molecular weight of 10000 to 30000, glass transition temperature (Tg) of -5 to 45 deg.C and OH value of 40 to 90 with ordinary non-yellowish type polyisocyanate, wherein the top coat composing the top coating layer essentially comprises 0.5 to 3 weight parts of organic filler for the top coat, the organic filler is polyamide, and the top coat composing the top coating layer comprises 0.1 to 3.0 weight parts of pure amine, preferably secondary amine for the top coat for promoting crosslinking between the polyester resin and the melamine resin and forming creases so that curing speed difference between inner and outer parts of the coating layer is generated during baking process of the top coating layer, thereby forming three-dimensional irregularities on the surface of the top coating layer.

Description

Colored steel sheet with single side embossed method

In the present invention, in order to give a three-dimensional effect in the form of a pattern on a steel sheet, using a metal roll engraved with a predetermined pattern (hereinafter referred to as emboss roll) during cold rolling of cold rolling, one side is pressed and applied to emboss after On the surface thereof, electroplating and hot-dip galvanized steel sheet for the purpose of improving corrosion resistance are selected and performed according to the use. In addition to the plated steel sheet, a known cold rolled steel sheet or a base plate such as a copper sheet or a stainless sheet may be used. After coating-type chromate treatment as a pretreatment for preventing corrosion and improving adhesion of paints on such a known base plate, the first layer is coated with paint for PCM (pre-coated metal) and paint for home appliances. And it relates to a single-sided embossed color steel sheet and a manufacturing method thereof so that the second polyester coating layer is formed.

The single-sided embossed steel sheet, which has been used up to now, has been manufactured at a relatively low cost, and has been used a lot. Instead, it is required to bend a known type of cold rolled and plated steel sheet, copper plate, etc. The general coating is performed after the processing.

In the painting process, first, a single-sided embossed cold rolled steel sheet coated with rust-preventive oil, a plated steel sheet, or the like is processed in an arbitrary form, followed by degreasing and spray coating. The embossed steel sheet spray-coated in this way has been widely used for exteriors such as panels or cases of building structural materials and home appliances because of its three-dimensional texture effect with uneven appearance.

However, degreasing and spray coating in the above process is to be discharged environmental pollutants, which makes it difficult to deal with the problem, the working environment is also poor, the problem of avoidance of work, etc., and also due to the characteristics of spray coating In order to solve these problems fundamentally, by eliminating the degreasing and painting process, the processed product can be completed through a simple process, that is, the single-sided embossed steel plate coated on the PCM line. It became necessary.

And another conventional embossed color steel sheet using a known steel sheet as a material, and after the PCM coating process, it was passed through the emboss roll to emboss the upper and lower sides together, which improved the environmental problems, but the material and coating There is a limitation in processing the embossed roll with a large right angle on the protective side of the face, and there is a disadvantage in that the surface is not well adhered in the overlapping parts when assembling the finished product and does not exhibit various and three-dimensional patterns.

In addition, another conventional technology in consideration of this is Korean Patent No. 197932 (one-sided embossed color steel sheet and its manufacturing method) which is filed and filed by the present applicant, which solves poor surface adhesion and PCM coating caused by the joining of double-sided irregularities. In the embossed part of the single-sided embossed steel sheet for the treatment of the coating technology without pores / bubbles, and the development of a coating to prevent various defects due to irregularities, that is, the treatment conditions and manufacturing method thereof have been improved. The resin (especially the top coat) disclosed in the above was unable to obtain the steel plate of optimum quality due to the color difference (uniform hiding force) generation and the deep workability in the angular portion where the surface irregularities were formed, and the surface appearance was also embossed irregularities. There has been a drawback of being relatively simple depending only on the pattern.

Therefore, the object of the present invention was devised in view of the above-mentioned problems, and it is possible to solve the environmental regulation problem according to the beautiful appearance and degreasing and painting process with a three-dimensional embossed steel sheet as a material, and shorten the process in the processing process. As well as to provide additional irregularities / wrinkles on the surface of the single-side embossed steel sheet as needed, to provide a natural appearance and low-cost single-sided embossed color steel sheet and a method of manufacturing the same.

Another object of the present invention is to improve the non-uniform hiding force (color difference) according to the embossed portion of the steel sheet than the top coating used in the conventional single-sided embossed color steel sheet and adhesion and workability such as deep workability according to the flexibility of the coating film An improved one-sided embossed color steel sheet and its manufacturing method are provided.

The object of the present invention as described above is to form a chromate layer on a known base steel sheet provided with embossing only on one side, and to form a coat on the chromate layer and to coat the coating material of the polyester resin as a top coat on top In the embossed color steel sheet, the polyester resin has a number average molecular weight of 10,000-30,000, a glass transition temperature (Tg) of -5 to 45 ° C., and an OH value of 40 to 90, and an oil-free polyester and a normal sulfur-free deformation. It is achieved by providing a single-sided embossed color steel sheet which is a modified oil-free polyester compound reacted with polyisocyanate.

In another aspect, the present invention is characterized in that the top coating constituting the top coating film optionally comprises 0.5 to 3 parts by weight of the organic filler with respect to the top coating, furthermore, the present invention is a top coating constituting the top coating film In order to promote crosslinking of the ester resin and melamine resin, 0.1 to 3.0 parts by weight of pure amine, preferably secondary amine, is added to the top coat, and if appropriately adjusted to provide the surface texture according to demand, A single-sided embossed color steel sheet is provided which makes a difference in the curing rate inside and outside the coating film during baking of the coating film to form a three-dimensional unevenness / wrinkles on the top coat film surface.

The preferred thickness of the coating film of the single-sided embossed color steel sheet according to the present invention is a top coat: 12 to 20 µm, a bottom coat: 8 to 12 µm, a chromate layer: 20 to 80 mg / m2, and a plating layer: 15 to 23 µm. .

The top coat used in single-sided embossed color steel sheet used polyester resin with molecular weight (number average molecular weight) of 6,000 ~ 9,000, but the adhesion and flexibility of coating due to the irregularities (emboss) of the steel sheet could not be enough to bend, There existed a disadvantage that peeling of a coating film is easy to occur in post-processing processes, such as a press.

Accordingly, the present inventors applied a polyester resin, which is a main resin of the paint used in the upper coat, to a embossed steel sheet using a linear structure of a main chain, and as a result, a steel sheet having significantly improved physical properties than a conventional colored steel sheet was found. The discovery of the fact that it can be produced leads to the present invention.

Furthermore, when pure amine is included as an essential ingredient included in the top coat, such amine not only promotes crosslinking of the resin, but also rises to the surface during baking of the coating film when necessary to adjust the amount of the coating film, if necessary, so that the curing speed of the surface of the coating film is increased. By advancing faster than the internal curing rate, wrinkles may be gradually formed on the surface by volume reduction according to the difference in the curing rate between the surface and the inside, thereby forming a more three-dimensional and natural uneven / wrinkled surface.

Hereinafter, the present invention will be described in more detail.

As the base plate, most of the known plates such as electroplated and hot dip plated steel sheets, cold rolled steel sheets, stainless steel plates, and the like are applicable.

The chromate layer is for improving the corrosion resistance of the steel sheet, the adhesion of the primer (lower coating material) to the steel sheet, and the coating type chromate layer is preferable.

First, the polyester resin which is the main resin used for the top coat of the present invention will be described. Generally, the resin for PCM paint (Regular Polyester) is a hydroxyl group (Hydroxyl Group), carboxyl in the backbone of the resin. Functional group such as Carboxyl Group is branched and has a network structure when crosslinking with melamine (eg Hexa-Methoxymethyl melamine) resin used as crosslinking agent (hardening agent) of coating film. Elongation was extremely limited.

On the other hand, the flexible polyester coating resin used for home appliances has a drawback of excellent elongation of the coating film because the main chain of the resin is a linear structure, but has a disadvantage of weak weather resistance, UV resistance, and corrosion resistance.

In order to compensate for such drawbacks, the main resin of the top coat and the bottom coat employed in the present invention has a number average molecular weight of 10,000 to 30,000 for the provision of physical properties such as flexibility of the coating film and the formation of good surface wrinkles as needed. The temperature (Tg) is -5 ~ 45 ℃, the compound prepared by reacting the oil-free polyester polymer resin with a OH value of 40 to 90 and a conventional sulfur-free polyisocyanate compound.

The polyisocyanate serves to partially compensate for physical properties such as weather resistance, UV resistance, corrosion resistance, etc. by reacting a portion of the polyester main chain substituted with a branched OH group (urethane bond). Isocyanate compounds that can be used include hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, 2,4,6-triisocyanatetoluene and similar properties. Can be applied.

Next, the melamine used as the crosslinking resin is preferably a methoxy type or methoxy butoxy mixed melamine having a number average molecular weight of 300 to 1,000. When butoxy melamine alone or a mixture of methoxy melamine and butoxy melamine is used, the compatibility with the polyester resin drops sharply, resulting in poor curing with P.Es, the main resin, and surface wrinkle formation as necessary. This is because melamine may transfer to the upper layer of the paint when attempted, which may interfere with the formation of surface wrinkles or cause poor workability.

Commercially available products include RESIMINE 755, RESIMINE 757, RESIMINE 751 (manufactured by SOLUTIA), CYMEL 1168, CYMEL 1170, CYMEL 232 (manufactured by CYTEL).

The curing accelerator constituting the topcoat is used to increase the density of the coating film by promoting crosslinking between the main resin polyester and the crosslinking resin melamine, and it is preferable to use an acid masked by blocking with amine. Typically, p-toluene sulfonic acid (Toluene Sulfonic Acid), dinonylnaphthalene sulfonic acid (Dinonylnaphthalene Sulfonic Acid) dodecylbenzene sulfonic acid (DDBSA, Dodesyl Benzene Sulfonic Acid) and the like are used.

In addition, epoxy masking sulfonic acid or epoxy resin masked sulfonic acid may be used. The amine is a material that can be dissociated by heat, and may also cause hardening of the top coat and / or wrinkles on the surface of the coat.

The top coat forming the top coat layer constituting the top layer of the coated steel sheet is a PCM paint that exhibits excellent physical properties on the surface of the embossed substrate, so as to maintain deep workability, weather resistance, UV resistance, corrosion resistance and scratch resistance. By using the designed polyester resin and melamine resin as a basis, it is characterized by improving the functionality and satisfying the beautiful surface appearance as needed.

In other words, the present invention, in addition to the excellent hiding properties of the embossed portion, deep processing properties, such as embossed on the surface of the steel sheet surface treated single-side embossed, forming irregularities and / or wrinkles as needed to induce a visual interest on the coating film surface The paint optionally comprises a certain amount of pure amine as a curing and / or creasing agent of the organic filler and the resin.

First, the filler as an essential ingredient for forming the unevenness / wrinkles added to the topcoat of the present invention, 0.5 to 3.0 parts by weight of the organic filler is added to the topcoat in order to give a three-dimensional appearance of the uneven shape to the dry coating and improve processability .

Such an organic filler not only gives a color to the surface of the steel sheet together with an organic / inorganic pigment component, but also gives an aesthetic three-dimensional appearance to the surface of the steel sheet.

The organic filler to be used is selected from plastic fillers (called nylon (NYLON) fillers) such as polyamide, polypropylene and polyethylene.

Amide is a stable material with excellent durability, chemical resistance, lubricity and high hardness, which improves the physical and chemical performance of coatings.

In the present invention, the amide added as needed for surface wrinkle formation is slightly melted on the surface of the solid amide when PMT reaches 100 ° C or more during the baking process of the paint to form a binder (resin) and an amide. By fusion at the surface, the unevenness of the natural material feel is formed in the coating film appearance.

At this time, if the colored amide is added as needed, the visual sensitivity of the surface can be variously expressed according to the color of the selected amide. In addition, transparent amides may be used to provide only unevenness, and colored amides may be used to give textures with coherent color changes to paint colors. Therefore, transparent or colored amides may be used alone or in combination for the purpose of application, and the degree of irregularities is also varied depending on the amount of polyamide filler added and the particle size selected. Properly mix and use within the range. If the polyamide filler to be added is 0.5% or less, the effect of unevenness is weak, weather resistance is weakened at 3% or more, more preferably in the range of 1 to 2%.

In consideration of the top coat dry thickness of 12 ~ 20㎛, it is preferable to select and use a transparent or colored spherical amide having a particle size of about 15-25 microns.

In the present invention, such organic fillers may be used alone or mixed with transparent and / or colored organic fillers to form irregularities / wrinkles as needed.In addition to the organic and inorganic pigments for color impartment, workability improvement such as deep workability and Constitutional pigments for coating film volume can be used.

The addition of organic and inorganic pigments and organic fillers together with the embossed pattern imparted to the steel plate itself over the entire surface of the coating film improves the workability of the uniform hiding power and deep workability, and if necessary, gives a sense of texture and natural materials. You can get a coating.

Next, pure amine, which is an auxiliary curing accelerator, will be described as another essential ingredient added to the top coat to promote curing and / or wrinkling of the coating film.

Pure amine is a component that serves as an auxiliary curing accelerator to promote crosslinking of the resin constituting the topcoat.The pure amine is PMT 170 ~ 190 ℃ during baking of the coated film as needed in addition to promoting curing by controlling the addition amount. It rises to the surface in the degree, and by gradually increasing the curing rate of the surface of the coating film surface than the internal curing rate is to gradually form wrinkles on the surface by volume reduction according to the difference between the surface and the curing rate.

As a result, the three-dimensional appearance of the embossed steel sheet surface is further improved.

As the amines used as such an auxiliary curing accelerator (wrinkle forming agent), both primary, secondary and tertiary amines can be used, of which secondary secondary amines are preferred. The reason is that primary and tertiary amines usually cause changes in color and severe surface shrinkage due to yellowing in the coating film, and secondary amines lead to no yellowing and moderate surface shrinkage.

When the amount of the amine used is insufficient, the surface and the inside of the coating are hardened at the same time, and wrinkles are difficult to occur. When the excessive amount is used, the coating film hardens so rapidly that it is difficult to express the soft texture of the surface of the coating. Properly adjusting the added amount in consideration of the characteristics will change the degree of the surface wrinkles are formed, accordingly, it is possible to express differently the feel felt with the visual three-dimensional.

The amount of pure amine added should be at least 0.1 part by weight based on the top coat and preferably 0.3 to 3.0 parts by weight.

Hereinafter, other components constituting the topcoat of the present invention will be described.

As the colored polyester-based top coat of the present invention, organic and inorganic pigments used in PCM paint can be used without limitation.

As a solvent, it is selected from hydrocarbon type and ester type as much as possible for uniform coating hardening and roll mark prevention.

It is preferable that the top coat of this invention has the following composition ratios.

division ingredient Content (weight ratio)% Suzy Polyester resin 25-40 Melamine resin 4-10 Fee Organic Pigments 2-5 Inorganic pigments 5-35 Sieving pigment 5-10 filler Organic filler 0.5-3.0 additive Deforming Agent 0.5-1.0 Leveling agent 0.5-1.0 Curing accelerator (including auxiliary accelerator) 0.5-6.0 Solvent Hydrocarbon type (Hydrocarbon type) 15-25 Ester system 15-25

Next, the following description will be given.

The primer used for the adhesion of the material may be a polyester primer, an epoxy primer, an acrylic primer, or a modified base. The commercially available polyester primer is YP 500 series of Korea Chemical Co., Ltd. , 8600 series of Construction Chemical Co., Ltd., Fine Coat p-331 of Samwha Paint.

In addition to its basic properties, such as general corrosion resistance, strengthening adhesion between top and embossed steel sheets, the degree of elongation is applied to provide a sufficient buffering effect at the interface between the material and the top coat. It does not develop and plays a role in being absorbed in the lower layer. Anticorrosive pigments should be used for the corrosion resistance of the undercoat, and like the top coat, organic and inorganic pigments used for PCM paints can be used without limitation.

The paint of the above characteristics is suitable for embossed steel sheet because it has good wettability to the embossed steel sheet, and the dry coating film has a three-dimensional sensation on the surface of the embossed steel sheet in addition to the excellent physical properties such as uniform hiding power and deep workability of the embossed portion. It is possible to provide a coated steel sheet having a functional characteristic of.

On the other hand, in the production of the coated steel sheet according to the present invention, the holding of the single-side embossed steel sheet in one step of the top or bottom of the two-stage (one set) of the tempered rolling work roll in the step of temper rolling the cold rolled steel sheet after annealing One side embossed work roll is installed to perform the temper rolling work to form one side embossed pattern.

Thereafter, the embossed cold rolled steel sheet is subjected to a degreasing step to select an electroplated or hot dip galvanized steel sheet on its surface according to the purpose.

Of course, in addition to the plated plated plate, a common cold rolled steel plate, a copper plate or a stainless plate may be used as the plate.

On the base plate, chromate treatment is applied to the surface with a line speed of 60 ~ 100mpm in a coating line with a thin film on the surface by a roll coating method, and dried at 60 ~ 140 ℃ temperature condition to form a chromate layer of 20 ~ 80mg / ㎡. On top of that, polyester antirust prima and colored polyester based top coat are formed thereon.

This highly processable polyester rust preventive primer has a dry coating thickness (D.F.T) of 8 to 12 µm, preferably 10 µm, and a colored polyester based coat having a thickness of 12 to 20 µm.

When the thickness of the top coat becomes less than 12㎛, the deep workability decreases, the uneven hiding power (color difference occurs), and the surface wrinkles formed as necessary are finely formed. After roll coding to have a thickness, the steel sheet roll-coated in a dry oven is dried by heating to 190 ~ 240 ℃ PMT (peak metal temperature).

The test results of the single-sided embossed steel sheet according to the present invention proved to be excellent in physical properties such as uniform hiding power of the embossed portion, excellent deep workability, and three-dimensional feeling, as compared with the conventional steel sheet (the product of Patent No. 197932). Examples for this are given below.

Specimen standards and coating conditions used in the examples are as follows,% means parts by weight.

-Coil standard: W (Width) 1040 × T (Thickness) 0.5mm GI (Molten zinc plated steel sheet)

-Dry coating thickness: Undercoat 10 ㎛, Top coat 15 ㎛

-Viscosity of work coat of paint (25 ℃, # 4 Ford cup) 40 seconds

-Top coat paint viscosity (25 ℃, based on # 4 Ford cup) 70 seconds

-Roll coating method: full reverse

-Hado: YP 500 series of Korea Chemical

Table 2 Composition of Top Paint

Topcoat Components Content (parts by weight) Example 1 Example 2 Example 3 100% polyester resin (ES series of SKI) 40 24 25 Melamine resin (cymel 300 series from Cytec) 10 6 6 Organic pigments (carbon black of LG Chem) 5 · Inorganic Pigments (TiO ₂ 902 / chrome yellow)) · 30 (25/5) 30 (25/5) Organic filler (VESTOSINT series of DEGUSSA-HULS company) 2.5 2.5 Extender pigment (barium sulfate) 10 . . Deforming agent (Japanese public company AC-300) 0.2 0.2 0.2 Leveling agent (URALAC company 60% URED DD-27) 0.3 0.3 0.3 Curing accelerator (50% Nacure series) 0.6 0.6 3 Co-promoters (secondary amine reagents) · · One Solvents (hydrocarbon and ester) 33.9 36.4 32

Table 3 shows the results of comparative tests of the coating film properties of the Examples and Comparative Examples of the present invention. A comparative example is the product of patent no.

Table 3

division Comparative example Example 1 Example 2 Example 3 1. Workability ○ ○ ○ ○ 2. Roll mark ○ ○ ○ ○ 3. Surface wrinkles and / or irregularities △ △ ○ ◎ 4. Solvent resistance 50 times 73 70 70 5. Pencil Hardness H- H + H + H + 6. Processability T-bending 2T 1T 0T 0T S-cupping △ ○ ◎ ◎ 7. Adhesiveness 80/100 100/100 100/100 100/100 8. IMPACT △ ○ ○ ○ 9. Chemical resistance 5% NaOH ○ ○ ○ ○ 5% HCl ○ ○ ○ ○ 10. Corrosion resistance (1000hr) ○ ○ ○ ○ 11.UV resistance 500hr 0.64 0.21 0.23 0.19 1000hr 1.50 0.66 0.63 0.68 12. Weather resistance 500hr 1.45 0.45 0.48 0.45 1000hr 4.15 1.85 1.86 1.83

◎: Very good ○: Good / △: Normal / ×: Poor

-Workability of 1: Pick up at the time of roll coating

-2 roll marks: the degree of marks in the field roll coating

-Surface wrinkles and / or irregularities of 3: degree of surface wrinkles and / or irregularities in addition to emboss irregularities of the dry coating film

-Solvent resistance of 4: M.E.K Rubbing

-Pencil hardness of 5: Numerical results of scratch resistance with "Uni Pencil" manufactured by Mitsubishi Corporation of Japan

-Machinability of 6: T-bending, cracking state after square cupping

-Adhesiveness of 7: 6mm cross cut

-Impact of 8: 1 / 2φx 1kg x 50cm

-Chemical resistance of 9: Color difference between test specimen and test specimen which was immersed in 5% NaOH, 5% HCl solution for 24 hours.

-Corrosion resistance of 10: S.S.T (solt spray test) 35 ℃ 5% Nacl, 1000hr

-U.V resistance of 11: Measured △ E value after measuring 20w × 20cm × 500hr

-Weather resistance of 12: Measure △ E after 300 hours of Xenon arc lamp

As shown in the above table, the single-sided embossed color steel sheet according to the present invention has a distinctive contour of the uneven surface than the spray powder coating method, as well as excellent workability such as uniform hiding power and deep workability than the conventional comparative example. It can be seen that by the irregularities / wrinkles given by the more sharp three-dimensional appearance.

This is because the present invention is uniformly formed on the embossed portion of the coating film coated by the affinity with the pigment according to the properties of the resin, the color difference is solved, and also due to the characteristics such as excellent adhesion with elongation, elongation, etc. The resin layer of the top coat with excellent elongation primarily with respect to physical pressure gives workability on the surface, and the second coat applied for corrosion resistance and adhesion is buffered at the interface between the material and the top coat. This is because the cracks of the material were not found to the top coat layer, but were sufficiently absorbed in the bottom coat layer to maximize the workability, and the appearance was more beautiful due to the irregularities / wrinkles formed on the embossed base surface.

As can be seen from the above, the single-sided embossed color steel sheet according to the present invention exhibited superior workability and clear three-dimensional appearance than the conventional single-sided embossed color steel sheet, and also showed excellent adhesiveness and uniform color difference of the uneven portion surface.

In addition, since it is manufactured by PCM coating, the final processing company can eliminate the degreasing and painting process when manufacturing with conventional spray coating, thereby preventing environmental pollution and avoiding work.

In addition, surface defects such as stain coating and pore generation do not occur due to the perfect wettability of the material and the paint even at high speed during painting. Compared with the color steel sheet roll-coated and coated on the plate, there is a characteristic having equal or more properties.

Claims (5)

A chromate layer is formed on a known base plate which is embossed only on one side, and forms a highly processable P.Es layer on the chromate layer, polyester resin as main resin, melamine resin as crosslinking agent, curing accelerator, and other additives. In the single-sided embossed color steel sheet which is coated with a resin composed of a solvent and the like on top, The polyester resin is a modified oil obtained by reacting an oil-free polyester having a number average molecular weight of 10,000-30,000, a glass transition temperature (Tg) of -5 to 45 ° C., and an OH value of 40 to 90 with a conventional sulfur-free polyisocyanate. Single-sided embossed color steel sheet characterized by a free polyester compound The single-sided embossed color steel sheet according to claim 1, wherein the topcoat constituting the topcoat film essentially includes 0.5 to 3 parts by weight of an organic filler with respect to the topcoat. The single-sided embossed color steel sheet according to claim 2, wherein the organic filler is polyamide. According to any one of claims 1 to 3, the top coating constituting the top coating film is to promote crosslinking of the polyester resin and melamine resin and 0.1 to 3.0 parts by weight of pure amine based on the top coating as a wrinkle forming agent Preferably, a single-sided embossed color steel sheet comprising a secondary amine to form a three-dimensional unevenness on the surface of the top coat film by making a difference in the curing rate inside and outside the coating film during the baking process of the top coat film In the process of temper rolling, the embossing roll is installed at one of the upper and lower working rolls, and the embossing is applied only to one side of the material by passing a known base plate there. Degreasing the cold rolled steel sheet in the base plate according to the use, if necessary, followed by electroplating, hot dip galvanizing or known plating: Applying a thin film of chromate on the base plate in a coating line and drying at a temperature of 60-140 degrees Celsius (PMT) to form a chromate layer of 20-80 mg / m ² : And The one-sided film according to any one of claims 1 to 4, which includes a step of rolling a polyester paint at a line speed of 40 to 90 MPM, followed by heating and drying at PMT 210 to 241 ° C to form a primer layer and a top coat. Method for producing embossed color steel sheet.