KR101977505B1 - Resin composition, the black resin coated steel sheet using the same, and the method of preparing the same - Google Patents

Abstract

The present invention relates to a resin composition, comprising 35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of an epoxy resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of wear resistant particles, 0.1 to 3 parts by weight of wax, and a remaining amount of a solvent, based on 100 parts by weight of the total composition, wherein the polyester resin has a higher molecular weight than that of the epoxy resin, and a glass transition temperature of the polyester resin is lower than a glass transition temperature of the epoxy resin. According to an embodiment of the present invention, a black resin steel sheet using the resin composition may have excellent surface appearance and excellent press workability even after applying quick drying punching oil. Also, by using a resin composition including a polyester resin and an epoxy resin, the black resin steel sheet secures high coating hardness and at the same time, has excellent punching oil resistance due to high resistance to water and oil.

Description

Technical Field [0001] The present invention relates to a resin composition, a black resin steel sheet using the resin composition, and a method of manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a resin composition, a black resin steel sheet using the same, and a method for producing the same.

The black resin steel sheet is a steel sheet which is applied to the rear cover of various TV displays such as LCD and LED. Coated steel plates are coated with black resin in the form of pre-coated metal (PCM), which is then shipped to the processing company as a sheet material in the size appropriate for the inch and finally transported to the press.

In the past, a high viscosity general soldering oil was applied in the press process, and press molding, rinsing, and drying processes were successively carried out to facilitate press formability and appearance. However, recently, the application of quick-drying hacking oil with a high volatilization rate and low viscosity compared to the conventional tack oil has been expanded to omit subsequent processes such as degreasing and washing after press. Quick-drying tack oil is a solvent that is not soluble in water, such as toluene, xylene, etc., in addition to aliphatic hydrocarbons. In addition to its ability to cool the heat generated by friction between the steel sheet and the press die during pressing, It plays a role.

From the viewpoint of supplementing the lubricity of the steel sheet, the quick-drying tack lubricant has a relatively low lubricity supplementing effect compared to the conventional tack lubricant, and the remaining unevenness occurs after the volatilization of the lubricant. Therefore, technological progress is required not only to immediately after the production of the steel sheet, but also to secure a beautiful appearance of the surface after the pressing process and to secure the processability of the steel sheet itself.

On the other hand, when the steel sheet is pressed in a shape having a complicated shape and a large processing depth, the adhesion between the coating layer and the coating layer and the lubricating property of the coating layer should be excellent in order to ensure workability. In recent years, induction heating method, which has excellent hardening efficiency compared to the hot air curing method which has been applied to most of the color coated steel sheet manufacturers at home and abroad, is being applied.

The induction hardening method is a merit of excellent hardening efficiency compared with a hot air hardening method in which heat is transferred by convection because the conductor is a steel sheet which is heated by induction current generated when a strip passes through a magnetic field.

However, in the case of induction hardening, it is relatively difficult to obtain a high surface density by sufficiently floating the wax in the coating layer, which contributes to ensuring the lubrication of the steel sheet, due to the short length of the hardening zone itself and the high- have.

Further, when the absolute content of the wax is large, securing the lubricity is relatively easy compared to the case where the absolute amount of the wax is large, but the crosslinking density may be lowered and the hardening force may be weakened. When the coating layer is cured, it is subjected to cooling and drying processes until it is wound. When the surface of the coating layer is inhomogeneous with the cooling water during the cooling process, surface defects such as circular stains are generated. It is noticeable in the type of spray being cooled.

Disclosure of the Invention The present invention has been conceived to solve the problems as described above. It is an object of the present invention to provide a resin composition capable of securing a good surface appearance and ensuring excellent workability after steel sheet coating, hardening and cooling, A black resin steel sheet using the same, and a manufacturing method thereof.

According to one aspect of the present invention, there is provided a resin composition comprising 35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of an epoxy resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of a wear- 0.1 to 3 parts by weight of a wax and a residual solvent, wherein the polyester resin has a higher molecular weight than the epoxy resin, and the glass transition temperature of the polyester resin is lower than the glass transition temperature of the epoxy resin A resin composition is provided.

The polyester resin may be contained in an amount of 87.5 to 97.8 parts by weight based on the total amount of the polyester resin and the epoxy resin.

The molecular weight of the polyester resin may be more than 5,000Mn and 50,000Mn or less, and the molecular weight of the epoxy resin may be 2,000Mn to 10,000Mn.

The glass transition temperature of the polyester resin may be 5 to 25 占 폚, and the glass transition temperature of the epoxy resin may be 30 to 80 占 폚.

The epoxy resin may include bisphenol A.

The abrasion-resistant particles may include at least one selected from polymethylmethacrylate and acrylic.

The wax may include at least one selected from silicon, paraffin, polypropylene, polyethylene and polytetrafluoroethylene.

The solvent may include at least one selected from the group consisting of propylene glycol methyl ether acetate, a ketone solvent, a hydrocarbon solvent, and a dibasic ester.

The resin composition may further comprise 0.5 to 2 parts by weight of an acid catalyst, 2 to 4 parts by weight of a pigment and 2 to 5 parts by weight of an additive.

According to another aspect of the present invention, A nickel nano-coating layer positioned on at least one surface of the backing steel sheet; A chromium-free underlying film disposed on the nickel nanocomposite layer; And a coating layer disposed on the Cr-free undercoat layer, wherein the coating layer comprises 70 to 80% by weight of carbon (C), 1 to 3% by weight of silicon (Si) Titanium (Ti): 2 to 6% by weight, and the balance oxygen (O).

The adhesion amount of the nickel nano-coating layer may be 50 to 300 mg / m ² .

The deposition amount of the chrome-free undercoat may be 300 to 1,800 mg / m ² .

The thickness of the coating layer may be 3 to 15 mu m.

The surface roughness of the coating layer may be 0.4 to 1.0 mu m.

The base steel sheet may be at least one selected from carbon steel, aluminum steel, aluminum alloy steel, stainless steel, copper steel, galvanized steel sheet, binary or ternary alloyed steel sheet including zinc.

According to another aspect of the present invention, there is provided a method of manufacturing a steel sheet, Forming a nickel nano-coating layer on at least one surface of the base steel sheet; Forming a chrome-free undercoat on at least one side of the backing steel sheet; And forming a coating layer by applying a resin composition on the chromium-free underlying coating and curing the coating composition, wherein the resin composition comprises 35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of a polyester resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of a wear resistant particle, 0.1 to 3 parts by weight of a wax, and the balance solvent, wherein the polyester resin has a higher molecular weight than the epoxy resin, Wherein the glass transition temperature of the polyester resin is lower than the glass transition temperature of the epoxy resin.

The curing may be performed by heat treatment at 210 to 240 ° C.

And washing and drying after the curing.

The black resin steel sheet using the resin composition according to one embodiment of the present invention can have a good surface appearance and excellent press workability even after application of quick-drying tacky oil.

Also, by using a resin composition containing a polyester resin and an epoxy resin, it is possible to provide a black resin steel sheet having a high coating film hardness and excellent tack oil resistance due to high resistance to water and oil.

Fig. 1 shows an induction hardening apparatus including a water-cooled part for simulating the process from cooling to drying after curing of a coated steel sheet.
2 shows a 250-ton servo press, a mold part, and a press material.
FIG. 3 is a graph showing that the specimens prepared in Examples and Comparative Examples were pressed at a load of 13 tons after applying quick-drying lubricant on a 250-ton servo press, and then observed the degree of damage of the beads and the coating on the drawing portion.

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

The present invention relates to a resin composition, a black resin steel sheet using the same, and a method for producing the same.

According to one aspect of the present invention, there is provided a thermoplastic resin composition comprising 35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of an epoxy resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of a wear- 0.1 to 3 parts by weight and the balance solvent, wherein the polyester resin has a higher molecular weight than that of the epoxy resin, and the glass transition temperature of the polyester resin is lower than the glass transition temperature of the epoxy resin. do.

The resin composition according to one embodiment of the present invention may include 35 to 45 parts by weight of a polyester resin and 1 to 5 parts by weight of an epoxy resin, based on 100 parts by weight of the total composition. If the amount of the polyester resin is less than 35 parts by weight, the flexibility of the coating layer may deteriorate due to the decrease of the polymer content and the pick-up may be deteriorated during the roll coating. If the amount exceeds 45 parts by weight, The external corrosion factor or the pressurized oil may penetrate into the inside of the coating film, resulting in corrosion resistance and occurrence of stains after pressing. When the epoxy resin is less than 1 part by weight, the effect of improving the hardness of the coating layer is insignificant. When the amount is more than 5 parts by weight, the degree of improvement of the coating film hardness is excessively high.

In the present invention, the polyester resin may have a higher molecular weight than that of the epoxy resin. More specifically, the polyester resin may have a molecular weight of 5,000 to 50,000 Mn, and the molecular weight of the epoxy resin may be 2,000 to 10,000 have. If the molecular weight of the polyester resin is less than 5,000Mn, it may be difficult to obtain flexibility and workability due to the short polymer length, and pick-up may be deteriorated when coating using the roll coating method. On the other hand, when the molecular weight of the polyester resin is more than 50,000Mn, the workability improving effect may be insignificant, and the viscosity of the paint may deteriorate and the crosslinking may be deteriorated after curing. In addition, when the epoxy resin is less than 2,000Mn, it may be difficult to secure workability. On the other hand, when the molecular weight of the epoxy resin is more than 10,000Mn, the effect of improving the hardness of the coating film may be insignificant, and the anti-oil resistance may be lowered.

In the present invention, the glass transition temperature of the polyester resin may be lower than the glass transition temperature of the epoxy resin, more specifically, the glass transition temperature of the polyester resin is 5 to 25 ° C, The transition temperature may be between 30 and 80 < 0 > C.

Glass transition temperature refers to the state transition temperature at which polymer molecular chains can move freely. More specifically, the lower the glass transition temperature, the lower the hardness and the better the workability. On the other hand, the higher the glass transition temperature, the lower the workability as the hardness increases.

When the glass transition temperature of the polyester resin is too low, the flexibility may be excellent, but the hardness after curing may be low and the coating layer may be easily damaged. On the other hand, when the glass transition temperature of the polyester resin is high, the hardness of the coating layer after the curing rapidly increases, and the workability may be deteriorated. Further, at 0 t-bending, cracks may be generated, and the adhesion may be lowered. In the specification of the present invention, 0t-bending means the most severe condition in the bending test for evaluating workability of a steel sheet. More specifically, since t-bending is determined depending on the number of steel plates entering between the bending members, the steel sheet satisfying the 0 t-bending condition means excellent workability.

If the glass transition temperature of the epoxy resin is too low, the hardness may be lowered after curing, and the coating layer may be easily damaged. On the other hand, if the glass transition temperature of the epoxy resin is high, the hardness of the coating layer may rapidly increase after curing, resulting in deterioration of processability. Further, at 0 t-bending, cracks may be generated, and the adhesion may be lowered.

Therefore, the resin composition of the present invention can be produced by mixing two kinds of resins of a 'low glass transition temperature-high molecular weight' polyester resin and a high glass transition temperature-low molecular weight epoxy resin, It is possible to secure both workability and anti-oil resistance.

On the other hand, the polyester resin may be contained in an amount of 87.5 to 97.8 parts by weight based on the total amount of the polyester resin and the epoxy resin. When the content of the epoxy resin having a lower molecular weight and a higher glass transition temperature than that of the polyester resin is less than 87.5, the degree of increase in the hardness of the coating film may be insignificant and the press workability may be lowered. Compared with the case where the polyester resin is used alone, The resistance may be lowered. On the other hand, when the content of the epoxy resin is more than 97.8, the effect of improving the tack resistance is small, but the press workability may be lowered. The epoxy resin is preferably a bisphenol A type epoxy resin.

The resin composition may further contain 3 to 10 parts by weight of melamine resin, 1 to 5 parts by weight of wear resistant particles, 0.1 to 3 parts by weight of wax and the balance solvent. When the content is less than 3 parts by weight, hardening of the coating film is insufficient and physical properties such as corrosion resistance and workability are deteriorated due to insufficient hardening. When the content exceeds 10 parts by weight, the effect of improving the hardening power is insignificant, Is lowered.

The abrasion-resistant particles may be an acrylic polymer-based polymer. For example, the abrasion-resistant particles may use at least one selected from polymethylmethacrylate and acrylic. The abrasion-resistant particles exist in a floating state on the surface of the coating film, thereby reducing the contact area between the press die and the steel sheet during press working, thereby improving scratch resistance, abrasion resistance and workability. More specifically, since the melting point of the abrasion-resistant particles is higher than the curing temperature of the coating, the abrasion-resistant particles remain in the form of solid particles even after curing.

When the resin composition of the present invention is cured to form a coating layer, the abrasion-resistant particles contained in the resin composition have a particle size distribution such that particles having an average particle diameter of 1.3 to 1.5 times the dry film thickness of the coating layer, Particles having an average particle diameter of 1.8 to 2.0 times may be mixed. Therefore, the size of the abrasion-resistant particles may vary depending on the thickness of the coating layer on the base steel sheet and the chrome-free undercoating layer.

When two kinds of particles different in the size of the abrasion-resistant particles are mixed, the scratch resistance, abrasion resistance, and press workability can be improved as compared with the case of applying one size particle. More specifically, the abrasion-resistant particles having a larger average particle diameter among the abrasion-resistant particles may be included in an amount of 10 to 30% by weight based on the total weight% of the abrasion-resistant particles. When the average particle diameter of the abrasion-resistant particles is too large or too large in comparison with the thickness of the coating layer, the surface roughness can be increased and the surface gloss can be reduced. In addition, it may lead to line delamination at the grain protrusion during the friction measurement.

The wax may comprise silicon, paraffin, polypropylene, polyethylene, polytetrafluoroethylene and a mixture of polyethylene-polytetrafluoroethylene, or a combination thereof.

The wax serves to impart lubricity to the steel sheet so that the steel sheet can be easily introduced along the shape of the mold during press forming. In addition, the wax contributes to improvement of surface lubrication by securing a high density in a dry film by ball bearing or blooming according to specific gravity, particle size and melting point.

When the content of the wax is less than 0.1 parts by weight in the present invention, the lubricity of the steel sheet after curing may be lowered. On the other hand, if the weight of the wax is more than 3 parts by weight, the effect of improving the lubricity of the steel sheet after curing is insignificant, and the crosslinking ability is lowered due to the wax floating on the surface, so that the corrosion resistance can be reduced. In addition, the reaction with the other oil becomes easy, and surface defects such as stains may occur at the time of flushing, and the surface appearance may be lowered.

The solvent may also include propylene glycol methyl ether acetate, a ketone system, a hydrocarbon system, a dibasic ester, or a combination thereof. However, the present invention is not limited thereto. When the content of the solvent is small, the viscosity becomes high and the solution stability and leveling property may be deteriorated. If the content of the solvent is too high, a high temperature or a long time is required to volatilize the solvent upon curing the solution, so that the productivity may be lowered. Also, surface defects such as sticking, blocking, etc. may occur during transportation.

The resin composition according to the present invention may further contain, if necessary, 0.5 to 2 parts by weight of an acid catalyst, 2 to 4 parts by weight of a pigment and 2 to 5 parts by weight of an additive.

The acid catalyst may be dinonylnaphthalenesulfonic acid, alkylbenzenesulfonic acid, or a mixture thereof. Further, the acid catalyst may include 0.5 to 2% by weight based on 100% by weight of the total composition. However, when the amount of the acid catalyst is less than 0.5 parts by weight, the degree of curing and the hardness of the chrome-free undercoat may be reduced. On the other hand, when the content of the acid catalyst exceeds 2 parts by weight, the workability may be deteriorated.

The pigment may be a mixture of carbon black and titanium oxide, but is not limited thereto, and the pigment may be included in an amount of 2 to 4 parts by weight. The pigment serves to impart color and opacity to the coating layer. When the amount of the pigment is less than 2 parts by weight, the hiding power of the chrome-free undercoating film to be described later is lowered, so that the appearance of the surface can not be secured. When the pigment is more than 4 parts by weight, the processability may be lowered.

The additive may be included in an amount of 2 to 5 parts by weight based on 100 parts by weight of the total composition. In addition, the additive may include an adhesion promoter, a leveling agent, a dispersant, and a quencher.

More specifically, the adhesion promoter may comprise a hydroxyl phosphate ester, or a combination thereof. In addition, the leveling agent may comprise polyacrylate, polysiloxane, or a combination thereof. The dispersing agent may include an acrylic polymer dispersant, a urethane-based polymer dispersant, or a combination thereof. The dispersant serves to disperse the atomized pigment to prevent aggregation.

In addition, the quencher may comprise amorphous silica. The quencher serves to reduce the gloss by inducing surface diffuse reflection. Therefore, the content can be adjusted according to the desired degree of gloss.

According to another aspect of the present invention, A nickel nano-coating layer positioned on at least one surface of the backing steel sheet; A chromium-free underlying film disposed on the nickel nanocomposite layer; And a coating layer disposed on the Cr-free undercoat layer, wherein the coating layer comprises 70 to 80% by weight of carbon (C), 1 to 3% by weight of silicon (Si) Titanium (Ti): 2 to 6% by weight, and the balance oxygen (O).

The base steel sheet is not particularly limited, but a carbon steel, an aluminum steel, an aluminum alloy steel, a stainless steel, a copper steel, a galvanized steel sheet, a binary or ternary alloy coated steel sheet including zinc, or a combination thereof may be used.

On the other hand, in the case of a galvanized steel sheet and an alloy coated steel sheet including zinc, nickel (Ni) nano coating may be included at the interface between the substrate iron and the plating layer. In the application of the nickel nano coating, the surface water quality is concealed by concealing the water-like defects, and the corrosion resistance of the steel sheet itself is improved, so that the thickness of the coating layer located on the chrome-free undercoating film and the undercoating film can be reduced.

The deposition amount of the nickel nanocomposite layer may be 50 to 300 mg / m < ² >. When the deposition amount of the nickel nano-coating layer is less than 50 mg / m ² , the surface quality may be poor and the corrosion resistance improving effect may be deteriorated. When the deposition amount of the nickel nano-coating layer is more than 300 mg / m ² , the effect of improving the surface quality and corrosion resistance is insignificant, but the manufacturing cost can be increased.

The chrome-free undercoat may be located on the nickel nano-coat layer and the adhesion amount of the chrome-free undercoat may be 300 to 1,800 mg / m < ² >. The chromium-free primer, if 300mg / m ² is less than the film, and the corrosion resistance becomes inferior coating film adhesion, coating weight is 1,800mg / m ² when the excess of the heat transfer efficiency of the coating layer formed on the Cr-free coating is reduced becomes a disadvantage light thermal .

On the chrome-free undercoating film, a coating layer formed by applying and curing the resin composition of the present invention is placed. The thickness of the coating layer on the chrome-free undercoat may be 3 to 15 占 퐉. If the thickness of the coating layer is less than 3 占 퐉, the corrosion resistance and the scratch resistance of the flat plate and the cross section may be deteriorated. In addition, the whiteness (L value) may increase due to the lowering of the hiding power of the chrome-free undercoating film. On the other hand, when the thickness of the coating layer is more than 15 mu m, the curing efficiency in induction hardening may be lowered, and the productivity may be lowered, and the sticking and blocking resistance may be lowered.

On the other hand, the surface roughness (Ra) of the coating layer may be 0.4 to 1.0 탆. If the surface roughness of the coating layer is less than 0.4 탆, the contact area between the die and the steel sheet increases during press working and the formation of pockets capable of storing other oil may be insignificant, resulting in deterioration of processability. On the other hand, The surface gloss may be lowered due to promotion, the surface quality may be lowered, and the surface texture may become rough.

According to another aspect of the present invention, there is provided a method of manufacturing a steel sheet, Forming a nickel nano-coating layer on at least one surface of the base steel sheet; Forming a chrome-free undercoat on at least one side of the backing steel sheet; And forming a coating layer by applying a resin composition on the chromium-free underlying coating and curing the coating composition, wherein the resin composition comprises 35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of a polyester resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of a wear resistant particle, 0.1 to 3 parts by weight of a wax and the balance solvent, wherein the polyester resin has a higher molecular weight than the epoxy resin, Is lower than the glass transition temperature of the epoxy resin.

The above-described steps for forming the nickel nanocomposite layer are well known in the art, and detailed description thereof will be omitted herein. do.

The step of coating and curing the resin composition may be performed by heat-treating at 210 to 240 ° C by using an induction device, and the coating may be cured by heat treatment at 210 to 240 ° C to complete the formation of the coating layer.

Further, it may further include washing and drying after the curing.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are intended to further illustrate the present invention and are not intended to limit the present invention.

Example 1

A nickel-coated nickel-coated steel sheet having an alkali-degreased thickness of 0.4 m was prepared. At this time, in the nickel-nano-coated zinc-coated steel sheet, the adhesion amounts of the nickel deposition and the zinc plating layer were 150 mg / m ² and 20 g / m ^2, respectively.

The chrome-free composition was coated on one surface of the nickel-nano-coated zinc-plated steel sheet, cured, washed and dried to form a chromium-free undercoating film, wherein the chromium-free coating film had an adhesion amount of 800 mg / m ² .

Then, the resin composition was prepared as shown in Table 1 below.

division ingredient Weight (g) Polyester resin Molecular weight 23,000 Mn, glass transition temperature 7 占 폚 40 Epoxy resin Bisphenol A type, molecular weight 5,000 Mn, glass transition temperature 65 占 폚 2 Pigment A mixture of carbon black (1.75 g), titanium oxide (2.25 g) 4 Dispersant Fumed silica 0.15 Melamine hardening resin Highly methylated < RTI ID = 0.0 > 9 Wax Silicon (0.1), polyethylene (0.2g)
A mixture of polyethylene-polytetrafluoroethylene (1.2 g) 1.5 Abrasion resistant particles Polymethylmethacrylate 15 mu m particles (1.66 g)
A mixture of polymethyl methacrylate 20 mu m particles (0.34 g) 2 Quencher Amorphous silica 1.3 Acid catalyst Dinonylnaphthalenesulfonic acid 0.8 Leveling agent Polyacrylate 1.5 Adhesion promoter Hydroxylphosphate ester 0.55 solvent A mixture of propylene glycol methyl ether acetate, cyclohexanone, aromanaphtha and dibasic ester 37.2

The resin composition was coated on the zinc plated steel sheet on which the chrome-free undercoating film was formed, cured to a peak metal temperature of 230 DEG C by induction heating, washed with water and dried, A resin steel sheet was produced. At this time, the thickness of the dried coating layer was 10 mu m.

FIG. 1 shows an induction hardening device including a water-cooled part. A showerhead and a ramp, which can control the water pressure, are installed at the outlet port of the rear stage sample, and the sample coated with solution of different composition is simulated Respectively.

Example 2

A black resin steel sheet was produced under the same conditions as in Example 1, except that 41 g of the polyester resin and 1 g of the epoxy resin were used.

Example 3

A black resin steel sheet was produced under the same conditions as in Example 1, except that 37 g of a polyester resin and 5 g of an epoxy resin were used.

Example 4

A black resin steel sheet was produced under the same conditions as in Example 1, except that a polyester resin having a molecular weight of 5,500 Mn was used.

Example 5

A black resin steel sheet was produced under the same conditions as in Example 1, except that a polyester resin having a molecular weight of 48,000 Mn was used.

Example 6

A black resin steel sheet was produced under the same conditions as in Example 1, except that a polyester resin having a glass transition temperature of 5 캜 was used.

Example 7

A black resin steel sheet was produced under the same conditions as in Example 1, except that a polyester resin having a glass transition temperature of 23 占 폚 was used.

Example 8

A black resin steel sheet was produced under the same conditions as in Example 1 except that the abrasion-resistant particles each contained 1.8 g and 0.2 g of particles having an average particle diameter of 15 탆 and 20 탆.

Example 9

A black resin steel sheet was produced under the same conditions as in Example 1, except that the abrasion-resistant particles each contained 1.4 g and 0.6 g of particles having an average particle diameter of 15 탆 and 20 탆, respectively.

Comparative Example 1

A black resin steel sheet was produced under the same conditions as in Example 1, except that 42 g of the polyester resin and 0 g of the epoxy resin were used.

Comparative Example 2

A black resin steel sheet was produced under the same conditions as in Example 1, except that 42 g of epoxy resin and 0 g of polyester resin were used.

Comparative Example 3

35 g of a polyester resin, and 7 g of a polyester resin were used in place of the polyester resin.

Comparative Example 4

A black resin steel sheet was produced under the same conditions as in Example 1, except that an epoxy resin having a molecular weight of 1,000 Mn was used.

Comparative Example 5

A black resin steel sheet was produced under the same conditions as in Example 1 except that an epoxy resin having a molecular weight of 12,000 Mn was used.

Comparative Example 6

A black resin steel sheet was produced under the same conditions as in Example 1, except that an epoxy resin having a glass transition temperature of 25 캜 was used.

Comparative Example 7

A black resin steel sheet was produced under the same conditions as in Example 1 except that an epoxy resin having a glass transition temperature of 90 캜 was used.

Comparative Example 8

A black resin steel sheet was produced under the same conditions as in Example 1, except that 38.2 g of a wax composed of 0.1 g of silicon, 0.2 g of polyethylene and 0.2 g of polyethylene-polytetrafluoroethylene was used.

Comparative Example 9

A black resin steel sheet was produced under the same conditions as in Example 1, except that 32.7 g of a wax composed of 0.4 g of silicon, 0.8 g of polyethylene, and 4.8 g of polyethylene-polytetrafluoroethylene and 32.7 g of a solvent were used.

Comparative Example 10

A black resin steel sheet was produced under the same conditions as in Example 1 except that abrasion resistant particles composed of 0.34 g of particles having an average particle diameter of 5 탆 and 1.66 g of particles having an average particle diameter of 15 탆 were used.

Comparative Example 11

1.66 g of particles having an average particle diameter of 15 탆 and 0.34 g of particles having an average particle diameter of 25 탆 were used in the same manner as in Example 1 except that abrasion resistant particles were used.

Comparative Example 12

1.9 g of particles having an average particle diameter of 15 탆 and 0.1 g of particles having an average particle diameter of 20 탆 were used in the same manner as in Example 1 except that abrasion resistant particles were used.

Comparative Example 13

A black resin steel sheet was produced under the same conditions as in Example 1 except that abrasion resistant particles composed of 1.2 g of particles having an average particle diameter of 15 탆 and 0.8 g of particles having an average particle diameter of 20 탆 were used.

Experimental Example 1: Evaluation of surface appearance

The surface appearance of the specimen produced in the induction hardening apparatus including the water-cooled part shown in Fig. 1 was evaluated.

More specifically, it is divided into? (Occurrence of surface defects such as excellent, white spots and the like),? (Normally, surface defects are present immediately after preparation of specimen but surface restoration is performed after leaving at room temperature), and X The evaluation results are shown in Tables 2 and 3 below.

(Poor) when a local gloss variation occurs or the gloss is lower than the reference value.

Experimental Example 2: Evaluation of friction coefficient

The frictional coefficient of the surface of the black resin sheet was evaluated by a friction tester. The black resin specimen was sheared to a size of 148 × 290 mm and the coefficient of friction was measured. A pressing force of 600 kgf, and a moving speed of 3.3 mm / s. In order to confirm the effect of friction coefficient by quick - drying tack - oil application, we compared friction coefficients after tack - oil application.

More specifically, MVP 840TW non-water-soluble plasticizer shares of VS & Ein Chemical Co., Ltd. were used for quick drying. The coefficient of friction was defined as the average value of the friction coefficient in the 45 to 185 mm section based on the total travel distance of 190 mm.

In the friction coefficient evaluation experiment, it is preferable that the friction coefficient is small and the friction coefficient graph according to the moving distance appears in parallel with the X axis.

More specifically, the evaluation results are shown in Table 2 below as? (Very excellent, less than 0.20),? (Excellent, 0.20 to 0.22),? (Usually 0.22 to 0.24) Respectively.

When measuring the coefficient of friction after coating with other oil, it is indicated as × (insufficient) when the coating is peeled or when a stick-slip occurs on the graph, and it is shown in Tables 2 and 3.

Experimental Example 3: Tensile 0t Bending Workability Evaluation Experiment

Using the coated steel sheets prepared in the above Examples and Comparative Examples, the workability was evaluated through tape peeling and bending crack observation after tensile 0t-bending.

The black resin sheet specimen was sheared 35 × 150 mm, 20% tensile and 0 t-bent, and Nichiban tape was adhered to the bending part and peeled off.

The 0 t-bending portion was observed with a stereo scope to check the degree of cracking. At this time, when the adhesion property of the coating film is inferior, the coating film appears on the tape.

Further, by observing the bending portion with a microscope, it can be confirmed whether or not the machined portion is stably maintained even after bending and peeling off the tape, and the degree of occurrence of cracks can be grasped. As a result, it is possible to predict whether or not it is possible to secure good workability at a portion where the coating film is deformed as in the curled portion of the press material edge.

At this time, the peeling of the tape was evaluated as? (Excellent, no peeling), X (poor, peeling occurred), bending cracks were evaluated as? (Very good, (Normal, fine cracks), x (insufficient, cracks, or surface film peeling), and the evaluation results are shown in Tables 2 and 3 below.

Experimental Example 4:

By immersing the steel sheet in the boiling water for 2 hours and then removing the surface, the degree of surface change is confirmed. When the surface hardening force is weakened, the boiling water penetrates into the coating layer and can cause a serious change in the surface such as blister .

Evaluation methods are shown in Tables 2 and 3 listed below as ○ (excellent, no surface change (no occurrence of blister), × (insufficient, blister occurrence).

Experimental Example 5: Evaluation of press formability

A 420 × 420 mm steel plate was prepared and applied with MVP 840TW non-water-soluble plasticizer (quick drying tack oil) of Vs & Ein Chemical Co., and then a load of 13 tons was applied to a SIMPAC 250 ton servo press (SV1P-250) The steel sheet was pressed.

In addition, the incidence of film damage was calculated by dividing the length of occurrence of peeling of the side surface of the bead portion or the side portion of the drawing portion by the whole circumference. At this time, even if peeling occurred in either the bead portion or the drawing portion, the peeling of the coating film was judged.

Evaluation methods were divided into ◎ (very good, less than 10%), ○ (excellent, 10-20%), △ (usually 20-30%), Evaluation results are shown.

division Example 1 Example 2 Example 3 Example 4 Example
5 Example 6 Example 7 Example 8 Example 9 Surface appearance ○ ○ ○ ○ ○ ○ ○ ○ ○ Coefficient of friction ◎ ○ ◎ ○ △ ◎ ◎ ○ ◎ 20% tensile 0t-bending Tape peeling ○ ○ ○ ○ ○ ○ ○ ○ ○ Bending crack ◎ ◎ ○ △ ◎ ◎ ○ ◎ ○ Beak ○ ○ ○ ○ ○ ○ ○ ○ ○ Press formability ◎ ◎ ○ ◎ ○ ◎ ◎ ○ ○

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Surface appearance △ △ ○ ○ ○ ○ ○ ○ X ○ X ○ X Coefficient of friction △ △ △ ○ △ △ X △ X △ X ○ X 20% tensile 0t-bending Tape peeling ○ X X X ○ ○ X ○ ○ ○ ○ ○ X Bending crack ◎ X X X ○ ◎ △ ○ ○ ○ △ ◎ △ Beak ○ ○ ○ ○ ○ ○ ○ ○ X ○ ○ ○ ○ Press formability ○ X △ △ △ △ △ X X △ △ △ ○

As shown in Table 2, the black resin steel sheets prepared in Examples 1 to 9 exhibited excellent results both in terms of surface appearance, friction coefficient measurement after coating with tack oil, and press formability evaluation, and after 0% bending , And the evaluation of the seepage resistance showed good results.

On the other hand, as shown in Table 3, in the case of the comparative example, it took time to restore the defects in the surface appearance immediately after the specimen was manufactured, or it was impossible to restore it at all. Measurement of the frictional coefficient and resistance to heat It can be seen that physical properties for heat are shown in comparison with the examples.

FIG. 3 is a graph showing the results of observing the degree of coating damage of the bead portion and the drawing portion on the two sides after pressing the specimen manufactured through the above-described Examples and Comparative Examples at a load of 13 tons after applying quick-drying lubricant in a 250 ton servo press. Referring to FIG. 3, in the case of the comparative example, the damage degree of the coating film between the drawing part and the bead part is very severe and the damaged area extends to the drawing wall part. On the other hand, The damage area is also small.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (18)

35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of an epoxy resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of a wear resistant particle, 0.1 to 3 parts by weight of a wax, Wherein the polyester resin comprises 87.5 to 97.8 parts by weight based on the total amount of the polyester resin and the epoxy resin,
The polyester resin has a higher molecular weight than that of the epoxy resin,
Wherein the glass transition temperature of the polyester resin is lower than the glass transition temperature of the epoxy resin.
delete The method according to claim 1,
Wherein the polyester resin has a molecular weight of more than 5,000 Mn and 50,000 Mn or less and a molecular weight of the epoxy resin is 2,000 Mn to 10,000 Mn.
The method according to claim 1,
Wherein the polyester resin has a glass transition temperature of 5 to 25 占 폚 and the epoxy resin has a glass transition temperature of 30 to 80 占 폚.
The method according to claim 1,
Wherein the epoxy resin comprises a bisphenol A type epoxy resin.
The method according to claim 1,
Wherein the abrasion-resistant particles comprise at least one selected from the group consisting of polymethylmethacrylate and acrylic.
The method according to claim 1,
Wherein the wax comprises at least one selected from the group consisting of silicon, paraffin, polypropylene, polyethylene and polytetrafluoroethylene.
The method according to claim 1,
Wherein the solvent comprises at least one selected from the group consisting of propylene glycol methyl ether acetate, a ketone-based resin, a hydrocarbon-based resin, and a dibasic ester.
The method according to claim 1,
0.5 to 2 parts by weight of an acid catalyst, 2 to 4 parts by weight of a pigment and 2 to 5 parts by weight of an additive.
Base steel sheet;
A nickel nano-coating layer positioned on at least one surface of the backing steel sheet;
A chromium-free underlying film disposed on the nickel nanocomposite layer; And
And a coating layer disposed on the chromium-free underlying coating,
Wherein the coating layer is formed from the resin composition of any one of claims 1 to 9.
11. The method of claim 10,
And the adhesion amount of the nickel nano-coating layer is 50 to 300 mg / m ² .
11. The method of claim 10,
Wherein the adhesion amount of the chrome-free undercoating film is 300 to 1,800 mg / m ² .
11. The method of claim 10,
Wherein the thickness of the coating layer is 3 to 15 占 퐉.
11. The method of claim 10,
Wherein the coating layer has a surface roughness of 0.4 to 1.0 占 퐉.
11. The method of claim 10,
Wherein the base steel sheet is at least one selected from the group consisting of carbon steel, aluminum steel, aluminum alloy steel, stainless steel, copper steel, galvanized steel sheet and zinc-based binary or ternary alloy coated steel sheet.
Preparing a base steel sheet;
Forming a nickel nano-coating layer on at least one surface of the base steel sheet;
Forming a chrome-free undercoat on at least one side of the backing steel sheet; And
Applying a resin composition on the chrome-free undercoating film and curing the resin composition to form a coating layer,
Wherein the resin composition comprises 35 to 45 parts by weight of a polyester resin, 1 to 5 parts by weight of an epoxy resin, 3 to 10 parts by weight of a melamine resin, 1 to 5 parts by weight of a wear resistant particle, 0.1 to 3 parts by weight and the balance solvent, wherein the polyester resin and the epoxy resin are contained in an amount of 87.5 to 97.8 parts by weight based on the total amount of the polyester resin and the epoxy resin,
The polyester resin has a higher molecular weight than that of the epoxy resin,
Wherein the glass transition temperature of the polyester resin is lower than the glass transition temperature of the epoxy resin.
17. The method of claim 16,
Wherein the curing is performed by heat treatment at 210 to 240 캜.
17. The method of claim 16,
Further comprising washing and drying after the curing.

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