KR20110059080A - Black resin steel sheet for back cover of flat-panel display and method of manufacturing the same - Google Patents

Abstract

PURPOSE: A black resin steel sheet for a back cover of a flat panel display and a manufacturing method thereof are provided to produce a lightweight back cover with corrosion resistance, heat resistance, and solvent resistance by applying a thin top and bottom coating on a galvanized sheet 0.3~0.5mm thick. CONSTITUTION: A black resin steel sheet for a back cover of a flat panel display comprises a base steel sheet(310) which is 0.3~0.5mm thick, a Cr-free treated layer(320) which is formed on the top of the base steel sheet, an undercoat layer(330) which is formed on the top of the Cr-free treated layer at a thickness of 1~4μm, a topcoat layer(340) which is formed on the top of the undercoat layer at a thickness of 50~10μm, and an aqueous anti-fingerprint resin layer(350) which is formed on the underside of the base steel sheet.

Description

BLACK RESIN STEEL SHEET FOR BACK COVER OF FLAT-PANEL DISPLAY AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a back cover that covers the back of a flat panel display device such as an LED TV, a PDP TV, and the like, and more particularly, to contribute to the weight reduction and cost reduction of the back cover due to the use of a thinner thickness and less paint. It can reduce the amount of VOC (Volatile Organic Compounds) and minimize the impact on human body and environment by not using harmful heavy metal such as chromium (Cr), lead (Pb), mercury (Hg), cadmium (Cd). A black resin steel sheet for a back cover of a flat panel display device, and a method of manufacturing the same.

BACKGROUND OF THE INVENTION Household flat panel display devices, such as LCD (Liquid Crystal Display) TVs, Plasma Display Panel (PDP) TVs, and the like, include a back cover that covers various units for displaying flat images on the back.

1 shows a back cover of an LED TV and a PDP TV.

Here, the LED (Light Emitting Diode) TV refers to a very thin thickness by applying the LED as a light source of the LCD TV.

Referring to Figure 1 (a) showing the side of the LED TV and Figure 1 (b) showing the side of the PDP TV, the back cover (110a, 110b) forms the rear appearance of each flat display device, the inside Various units for displaying a planar image of the cover are covered from the back side.

The back covers 110a and 110b mainly use black steel sheets.

2 is a cross-sectional view illustrating a black steel plate for a back cover of a conventional flat display device.

Referring to FIG. 2, the black steel sheet illustrated is mainly a base steel plate 210 having a minimum thickness of 0.5 mm, and a pretreatment layer 220 having a thickness of 0.2 μm to 0.3 μm and a 5 μm thickness on the base steel plate 210. The undercoat 230 and the top coat layer 240 having a thickness of 20 μm are sequentially formed. In addition, a clear coating layer 250 having a thickness of 1 μm is formed below the base steel plate 210.

Conventionally, as the base steel sheet 210, a steel sheet having a thickness of at least 1 mm was used. The reason was that sufficient strength was not secured when the thickness of the steel sheet was less than 1 mm. Therefore, conventionally, the strength is complemented by using a relatively thick steel sheet of 1 mm or more.

As described above, conventionally, the base steel plate constituting the back cover of the flat panel display device is heavy and thick, so that not only the back cover but also the entire flat display device has a problem in that the weight and the weight of the flat display device are limited.

In addition, in the related art, a clear coating layer 250 is formed on the lower side of the base steel plate 210, that is, the surface in contact with various units for displaying a planar image, and in this case, an excellent effect in terms of protecting the lower surface of the base steel plate 210. However, there is a problem that is vulnerable to fingerprints or other contaminants of the operator during the flat display device assembly process.

In addition, the pretreatment layer 220 formed on the base steel plate 210 in order to improve the coating adhesion of the undercoat 230, etc., includes chromium, and chromium (Cr) is a harmful component to the human body. Should be.

Therefore, there is a need for a black steel sheet for a back cover of a flat panel display device that can reduce the weight and cost of the back cover, and can secure strength and other physical properties without using a toxic metal such as chromium.

An object of the present invention is to contribute to the weight reduction and cost reduction of the back cover by using a thin thickness and less paint, while ensuring the corrosion resistance heat resistance and solvent resistance, reducing the amount of VOC (Volatile Organic Compounds), chromium (Cr), lead (Pb) ), To provide a black resin steel sheet for the back cover of a flat panel display device that can minimize the impact on the human body and the environment without using harmful heavy metals such as mercury (Hg) and cadmium (Cd).

Another object of the present invention is to use a thin steel plate of 0.3 ~ 0.5mm, and by using a coating having a special composition in the coating of the upper and lower surfaces by reducing the amount of paint more than 50% compared to the conventional paint usage VOC It is to provide a method for manufacturing a black resin steel sheet for a back cover of a flat panel display device that can contribute to reduction and cost reduction.

A black resin steel sheet for a back cover of a flat panel display device according to an embodiment of the present invention for achieving the above object is a base steel sheet; A chromium-free pretreatment layer formed on the base steel plate; An undercoat layer formed on the chromium-free pretreatment layer; A top coat layer formed on the bottom coat layer; And an aqueous anti-fingerprint resin layer formed under the base steel plate, wherein the undercoat is formed to have a thickness of 1 to 4 μm, and the top coat layer is formed to have a thickness of 5 to 10 μm.

Method of manufacturing a black resin sheet for a back cover of a flat panel display device according to an embodiment of the present invention for achieving the above another object is (a) a chromium-free to 0.05 ~ 0.1㎛ thickness on the base steel sheet of 0.3 ~ 0.5mm thickness Forming a pretreatment layer; (b) forming an undercoat layer having a thickness of 1 to 4 μm on the chromium-free pretreatment layer; (c) forming a top coat layer having a thickness of 5 to 10 μm on the undercoat layer; And (d) forming an aqueous anti-fingerprint resin layer having a thickness of 0.5 to 1.5 μm under the base steel sheet.

The black resin steel sheet for back cover of the flat panel display device according to the present invention uses a thin galvanized steel sheet of 0.3 to 0.5 mm, and the outer coating thickness is only about 10 μm in total for the undercoat and top coat layers. And there is an advantage to ensure solvent resistance.

In addition, the black resin steel sheet according to the present invention has the advantage that can contribute to the weight reduction and cost reduction as a whole of the back cover and the flat display device through the use of the thin plate-like galvanized steel sheet and less paint.

In addition, the black resin sheet according to the present invention reduces the amount of VOC (Volatile Organic Compounds) and does not use harmful heavy metals such as chromium (Cr), lead (Pb), mercury (Hg), cadmium (Cd) It is an environmentally friendly material that can minimize the impact.

Hereinafter, a black resin sheet for a back cover of a flat panel display device according to a preferred embodiment of the present invention and a manufacturing method thereof will be described in detail with reference to the accompanying drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and those skilled in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Figure 3 shows a cross-sectional view of the black resin sheet for back cover of the flat panel display device according to the present invention.

Referring to FIG. 3, the black resin steel sheet 300 according to the present invention includes a base steel sheet 310, a chromium-free pretreatment layer 320, an undercoat layer 330, a top coat layer 340, and an aqueous anti-fingerprint layer 350. It includes.

Base steel plate

The base steel sheet is a steel sheet having a thickness of 0.3 to 0.5 mm, and a galvanized steel sheet may be used to improve corrosion resistance and durability. The galvanized steel sheet may be applied to hot-dip galvanized steel sheet, alloyed hot-dip galvanized steel sheet, electro-galvanized steel sheet and the like.

The zinc adhesion amount of the base steel sheet is preferably 10 to 60 g / m ² based on one side. If the plating deposition amount is less than 10g / m ² , the corrosion resistance may be lowered, and if the plating deposition amount exceeds 60g / m ² there is a problem that the productivity of the base steel sheet itself is lowered due to a decrease in the plating rate.

Chrome-free Pretreatment layer

The chromium-free pretreatment layer 320 is formed on the base steel plate 310 to improve corrosion resistance of the steel plate and adhesion of the undercoat layer. Here, the upper portion of the base steel plate 310 means the outer surface of the back cover, the lower portion of the base steel plate 310 means the inner surface of the back cover.

In the present invention, the pretreatment layer 320 does not include chromium (Cr). In the case of chromium (Cr) is commonly used to impart corrosion resistance, it is not preferable that chromium is used because it is an environmental and human harmful element. Accordingly, in the present invention, as a composition for forming the chromium-free pretreatment layer 320, using a composition capable of forming a zinc fluoride complex layer, the galvanized layer 311 and the undercoat layer 330 of the base steel sheet 310 Secure adhesion with Through the chromium-free pretreatment layer 320, crosslinking of the COOH group of the undercoat layer 330 with the metal or the hydroxyl group of the zinc plated layer 311 may occur, and the adhesion between the base steel sheet by hydrogen bonding may be improved.

The chromium-free pretreatment layer 320 is formed to a thickness of 0.05 ~ 0.1㎛. When the chromium-free pretreatment layer 320 is formed to a thickness of less than 0.05 μm, adhesion to each of the base steel sheet and the undercoat layer may not be secured, and when formed to a thickness exceeding 0.1 μm, workability may be inhibited.

The composition for forming the chromium-free pretreatment layer comprises a composition comprising 1 to 5% by weight of phosphoric acid, 0.1 to 1% by weight of hydrogen hexafluorozirconate (IV), 1 to 5% by weight of titanic fluoride, and a balance of water. Can present

Phosphoric acid is added to improve adhesion to the zinc plated layer 311 of the base steel sheet 310. When the phosphoric acid is added in less than 1% by weight can not be expected to improve the adhesion, when the phosphoric acid is more than 5% by weight causes entanglement and the like to lower the stability of the composition.

Hydrogen hexafluorozirconate (IV) is added to improve the corrosion resistance. In order to obtain such an effect, hydrogen hexafluorozirconate (IV) should be added in an amount of 0.1 wt% or more in the composition, but when added in excess of 1 wt%, there is a problem of inhibiting adhesion.

Titanium fluoride is added to improve the corrosion resistance and to form a zinc fluoride complex salt layer. When the fluorinated titanic acid is added in less than 1% by weight, the addition effect may not be obtained. When the amount of the titanic acid fluoride is more than 5% by weight, a large amount of precipitate in the composition may be generated to lower chemical resistance.

Subfloor

The undercoat 330 is formed on the chromium-free pretreatment layer 320 to enhance the adhesion of the top coat layer 340, and also acts as a buffer between the base steel plate 310 and the top coat layer 340. The undercoat 330 includes polyester to secure excellent adhesion through curing, and can maximize non-toxic and corrosion resistance through an appropriate amount of anti-corrosive pigment and anti-corrosive aid.

The undercoat 330 may be formed to a thickness of 1 ~ 4㎛. When the undercoat 330 is formed to have a thickness of less than 1 μm, the adhesion of the top coat layer 340 and the buffering action between the base steel plate 310 and the top coat layer 340 may not be expected. If the thickness of more than 4㎛ results in an increase in the amount of paint only without further improvement of physical properties.

The composition for forming the undercoat layer 330, 1 to 5% by weight of carbon black, 10 to 30% by weight of polyester, 5 to 10% by weight of rust preventive pigments, 1 to 5% by weight of rust preventive additives and residual amount of solvent The composition can be presented.

Carbon black is added to color the undercoat layer black. Conventionally, since the thickness of the top coat layer was thick, the transparent coat or the white paint was mainly used.

 However, in the present invention, the thickness of the black top coat layer is reduced by about 50%. In this case, the black pigment should be added to the top coat layer more than twice to maintain uniform color. In this case, since it adversely affects the scratch resistance and workability of the top coat layer, in the present invention, the bottom coat layer is pre-colored with carbon black so that the uniform black chromaticity can be maintained even if the thickness of the top coat layer is reduced to about half of the conventional one. do.

 The carbon black is preferably added in an amount of 1 to 5% by weight of the total weight of the composition. When carbon black is added in an amount less than 1% by weight, the undercoat does not become a uniform black color as a whole, and carbon black is 5% by weight. If it is added in excess, there is a problem that the adhesion decreases.

Polyester plays a role of ensuring excellent adhesion. Such polyester is preferably added in an amount of 10 to 30% by weight of the total weight of the composition. If the polyester is added in less than 10% by weight, the adhesiveness of the undercoat layer is lowered, if the polyester exceeds 30% by weight, the adhesiveness is excellent but there is a problem that other physical properties such as corrosion resistance of the undercoat layer may be lowered.

Antirust pigments and antirust additives are added to ensure the corrosion resistance of the undercoat. The rust preventive pigment and the rust preventive additive are preferably added in an amount of 5 to 10% by weight and 1 to 5% by weight of the total weight of the composition. This is because the rust-preventing effect can be obtained without inhibiting other physical properties in the above range.

Top floor

The top layer 340 is formed on the upper layer 340 and forms an outer surface of the back cover. In addition, the top coat layer 340 maintains an appropriate balance of hardness and workability in order to prevent cracks, scratches or peeling of the coating film during molding of the back cover. In addition, the top coat 340 has excellent slimness and imparts a good surface texture, including acrylic beads.

The top coat 340 may be formed to a thickness of 5 ~ 10㎛. If the top coat layer is formed to a thickness of less than 5㎛ decreases the physical properties such as corrosion resistance, scratch resistance, etc. If the top coat layer is formed to a thickness of more than 10㎛ increases the paint usage without further improvement of the physical properties.

The top coat layer 340 may be formed from a composition comprising 1 to 10% by weight of black pigment, 20 to 50% by weight of polyester, 1 to 10% by weight of acrylic beads, 1 to 10% by weight of a matting agent, and the remaining amount of solvent. have.

Black pigment plays a role in constituting the black appearance. In this case, the black pigment may be a mixture of 99.0 to 99.9 wt% of carbon black pigment and 0.1 to 1 wt% of yellow pigment.

Black pigment is preferably added in 1 to 10% by weight of the total weight of the composition. If the black pigment is less than 1% by weight, the overall appearance of black appearance is lowered, and if it exceeds 10% by weight, physical properties such as adhesion may be inhibited due to precipitation in the composition.

Polyester serves to impart adhesion through curing. Since the top coat layer 340 requires more adhesion than the bottom coat layer 330, the polyester is added to the top coat layer 340 in a somewhat high content ratio. The amount of such polyester added may represent 20-50% by weight of the total weight of the composition.

The top layer 340 may further include a flatting agent such as silica (SiO ₂ ) and acrylic beads in a content ratio of 1 to 10% by weight, respectively, in order to reduce gloss or to impart scratch resistance. . The matting agent and the acrylic bead improve the gloss reduction effect and scratch resistance in the range of not lowering other physical properties in the addition amount.

Various hydrocarbon solvents, ketone solvents and ester solvents may be used, and these solvents may be used alone or in combination of two or more thereof.

Suseong Infinite Resin Layer

The aqueous inner fingerprint layer 350 is formed under the base steel plate 310 to form an inner surface of the back cover. The aqueous anti-fingerprint resin used in the present invention is a resin having an anti-fingerprint property of a water-soluble type, and has excellent base adhesion and corrosion resistance, heat resistance, chemical resistance, and workability, and lubricity.

The aqueous fingerprint fingerprint layer 350 may be formed to a thickness of 0.5 ~ 1.5㎛. When the aqueous anti-fingerprint layer 350 is formed to a thickness of less than 0.5 ㎛ can not ensure the properties of corrosion resistance, heat resistance, etc., if formed to a thickness of more than 1.5 ㎛ the properties are no longer improved and the amount of the aqueous fingerprint This increases, which contributes to a rise in back cover manufacturing costs.

Acrylic resin 1 to 10% by weight, urethane resin 1 to 10% by weight, zirconium oxide 10 to 30% by weight, silica 20 to 40% by weight, ethanol 1 to 5 as a composition capable of forming the aqueous fingerprint fingerprint layer 350 A composition can be presented that includes weight percent and residual water.

The acrylic resin and urethane resin complement the chemical resistance and processability in the resin layer, and serves to secure water resistance, scratch resistance and the like. These acrylic resins and urethane resins are preferably added in 1 to 10% by weight of the total weight of the composition, respectively. If the acrylic resin or urethane resin is added in less than 1% by weight, the above addition effect is not obtained, and when the acrylic resin or urethane resin is added in excess of 10% by weight, entanglement in the composition causes uniformity of the numerical layer. Inhibits.

Zirconium oxide serves to improve the corrosion resistance in the resin layer. Such zirconium oxide is preferably added in a content ratio of 10 to 30% by weight of the total weight of the composition. If zirconium oxide is added in less than 10% by weight can not secure the corrosion resistance of the lower surface of the black resin steel sheet, when added in excess of 30% by weight inhibits the stability of the composition to lower the physical properties such as chemical resistance, water resistance .

Silica lubricates in the resin layer to improve the rubbing properties and processability, and also acts as a matting agent. Preferably, the silica is added in an amount of 20 to 40% by weight of the total weight of the composition. If the silica is added in an amount less than 20% by weight, the rubbing property may be degraded. When the silica is more than 40% by weight, other physical properties such as strength may be used. Can be degraded.

Ethanol controls the viscosity in the composition and serves to increase the antitumor effect with the silica. Such ethanol is preferably added in an amount of 1 to 5% by weight of the total weight of the composition. If it is added less than 1% by weight ethanol addition effect is not obtained, the addition of more than 5% by weight of ethanol becomes a factor of the increase in cost.

Figure 4 shows the embossed pattern of the black resin steel sheet surface, Figure 5 shows the form of a roll that can transfer the embossed pattern.

The embossed pattern may be a random pattern as shown in (a) of FIG. 4, and may be a wood pattern as shown in (b) of FIG. 4.

The black resin steel sheet may transfer the corresponding embossed pattern formed on the roll 500 to the upper surface of the black resin steel sheet by using the roll 500 shown in FIG. 5 to reinforce additional functionality. Through this, an embossed pattern as shown in (a) and (b) of FIG. 4 may be formed on the surface of the black resin steel sheet.

The depth 510 of the embossed pattern may be determined by the depth of the roll 500 as illustrated in FIG. 5, and may be 1 to 200 μm deep from the upper surface of the black resin steel sheet.

Hereinafter, a method of manufacturing a black resin sheet for back cover of a flat panel display device according to the present invention will be described.

6 is a flowchart illustrating a method of manufacturing a black resin sheet for a back cover of a flat panel display device according to the present invention.

Referring to Figure 6, the black resin steel sheet manufacturing method shown is a chromium-free pre-treatment layer forming step (S610), the undercoat layer forming step (S620), the top coat layer forming step (S630) alc aqueous fingerprint resistant resin layer forming step (S640) Include.

In the chromium-free pretreatment layer forming step (S610), a chromium-free pretreatment layer is formed to a thickness of 0.05 μm to 0.1 μm on the base steel plate having a thickness of 0.3 μm to 0.5 mm.

Specifically, after applying a composition containing 1 to 5% by weight of phosphoric acid, 0.1 to 1% by weight of hydrogen hexafluorozirconate (IV), 1 to 5% by weight of titanium fluoride, and the remaining amount of water, The chromium-free pretreatment layer is formed by drying at the temperature of 60-140 degreeC.

The chromium-free pretreatment layer may be formed with an adhesion amount of 30 to 150 mg / m ² . When the adhesion amount of the chromium-free pretreatment layer is less than 30 mg / m ² , the adhesion to the base steel sheet 310 is lowered. When the adhesion amount exceeds 150 mg / m ² , uniform adhesion is difficult on the entire steel sheet, and chromium is formed. The thickness of the free pretreatment layer becomes thick.

Next, in the step of forming the undercoat layer (S620) to form an undercoat layer of 1 ~ 4㎛ thickness on the chromium-free pretreatment layer.

Specifically, a composition comprising 1 to 5% by weight of carbon black, 10 to 30% by weight of polyester, 5 to 10% by weight of rust preventive pigment, 1 to 5% by weight of rust preventive adjuvant, and a residual amount of solvent on a chromium-free pretreatment layer After coating, it is dried at a temperature range of 170 ~ 240 ℃ to form a undercoat layer.

Next, in the top layer forming step (S630) to form a top layer of 5 ~ 10㎛ thickness on the top layer.

Specifically, a composition comprising 1 to 10% by weight of black pigment, 20 to 50% by weight of polyester, 1 to 10% by weight of acrylic beads, 1 to 10% by weight of a matting agent, and the remaining amount of solvent is applied onto the undercoat. After that, it is dried at a temperature range of 170 ~ 250 ℃.

In forming an aqueous fingerprinting layer (S640), an aqueous fingerprinting layer having a thickness of 0.5 to 1.5 µm is formed on the lower portion of the base steel sheet.

Specifically, a composition comprising 1 to 10% by weight of acrylic resin, 1 to 10% by weight of urethane resin, 10 to 30% by weight of zirconium oxide, 20 to 40% by weight of silica, 1 to 5% by weight of ethanol and the balance of water After coating on the lower steel sheet, it is dried at a temperature range of 170 ~ 240 ℃ to form an aqueous anti-fingerprint resin layer.

The aqueous anti-fingerprint layer is preferably formed at an adhesion amount of 1,000 mg / m ² , and may be formed at an adhesion amount of 950-1,050 mg / m ² when considering an error range of 5%. When the aqueous fingerprinting layer is formed with an adhesion amount of less than 950 mg / m ² , workability and adhesion may be reduced, and when the adhesion amount of the aqueous fingerprinting layer exceeds 1050 mg / m ² , electrical conductivity may be reduced.

The chromium-free pretreatment layer forming step (S610), the undercoat layer forming step (S620), the top coat layer forming step (S630), and the aqueous fingerprint resistant layer forming step (S640) may each be performed at a line speed of 50 to 150 mpm.

On the other hand, after forming the top coat layer or after forming the aqueous-fingerprint resin layer, in order to improve the functionality and appearance of the produced black resin steel sheet, it may further include an embossing pattern forming step (S650).

The formation of the embossing pattern may be performed using a roll having a corresponding pattern formed on the surface as shown in FIG. 5, and the embossing pattern may be formed to a depth of 1 to 200 μm from the upper surface of the black resin steel sheet.

As described above, the method for manufacturing a black resin sheet for back cover of the flat panel display device according to the present invention can reduce the amount of the composition used by 50% or more compared to the conventional method by forming a thin thickness of each layer in each step. The manufacturing cost of the back cover of the flat panel display device can be reduced.

In addition, the method for producing a black resin steel sheet according to the present invention can reduce the amount of VOC (Volatile Organic Compounds), which is an eco-friendly manufacturing method, and all compositions do not contain harmful heavy metals such as chromium, lead, mercury, and cadmium, which are harmful to humans. Does not have features.

Example

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

1. Back cover Of black resin  Produce

As a base steel plate, a chromium-free pretreatment layer, an undercoat layer, and a top coat layer were formed on a 0.5 mm hot-dip galvanized steel sheet in a 3coat 3bake method. At this time, the thickness of each layer was 0.1 micrometer of chromium free pretreatment layers, 2 micrometers of undercoat layers, and 8 micrometers of top coat layers.

Subsequently, an aqueous anti-fingerprint layer was formed at a thickness of 1 μm under the hot-dip galvanized steel sheet.

Table 1 shows specific conditions for forming each layer.

TABLE 1

As Comparative Example 1, a 40 μm embossed steel sheet having a thickness of 0.5 mm was used. As a Comparative Example 2, an 80 μm embossed steel sheet having a thickness of 0.5 mm was used.

2. Mechanical Properties

Basic mechanical properties of the Examples and Comparative Examples 1 and 2 are as shown in Table 2.

TABLE 2

Referring to Table 2, the yield strength (YP) and the tensile strength (TS) of the Example showed slightly lower values than Comparative Examples 1 to 2, but elongation (El), n value and r value were lower than those of Comparative Examples 1 to 2. Slightly higher. That is, in the case of the embodiment it can be seen that the moldability and workability is slightly better without a great difference from the comparative example in terms of strength.

3. Property evaluation

(1) Property evaluation method and standard

1) corrosion resistance

Corrosion resistance evaluation was confirmed by spraying 5% saline for 8 hours and drying 16 hours three times, and then peeling the coating, lifting and corrosion of the plated surface, the presence of rust.

2) moisture resistance

After evaluating moisture resistance for 48 hours at a temperature of 40 ° C. and a humidity of 90-95%, abnormalities such as coating, printing, and color were confirmed.

3) heat resistance

After the heat resistance evaluation was left at 60 ℃ for 7 hours, it was confirmed whether the change of the injection molding, discoloration of the coating surface, the fall of the adhesive product.

4) temperature cycle

In the temperature cycle evaluation, 0.5 cycles at 130 ° C. and 0.5 hour at 60 ° C. were repeated for 1 cycle, and after 12 cycles were repeated, change, cracks, shrinkage, warpage, gloss change, printing, and abnormality of the coating surface were confirmed.

5) Coating adhesiveness

In the coating adhesion evaluation, after the Scotch Tape was completely adhered to the printing and coating surface, the coating film was rapidly peeled off in the 90 ° direction, and then the adhesion between the printing and the coating film was confirmed.

6) Pencil hardness

The pencil hardness was evaluated by using a uni pencil (manufactured by Mitsubishi, Japan), drawing a line with a 45 ° inclination with an H pencil, applying a load of 500 g, and checking the degree of scratches on the coating surface.

7) wear resistance

Abrasion resistance evaluation was carried out at 500g / cm ² fusion load, 5,000 times at Strock 5cm, reciprocating 50 times / min, and then confirmed whether the peeling and peeling occurs during the printing, coating film surface wear.

8) ethanol resistant

In ethanol resistance evaluation, reagent 1, 99.5% Ethyl Alcohol was dropped on the coating film, and left at room temperature to check whether whitening and gloss were changed.

9) methanol resistance

Methanol resistance evaluation was carried out by dropping the first grade 99.5% Methyl Alcohol on the coating film and left at room temperature to confirm the whitening and gloss change.

10) Methanol Abrasion

Methanol abrasion evaluation was performed after a 500 g / cm ² round trip 50 times / minute and a stroke of 5 cm on a cotton ball moistened with 99.5% pure methanol, and whitening, gloss change and abnormality of the coating film were confirmed.

11) Ethanol Abrasion

The ethanol abrasion evaluation was performed after a 500 g / cm ² reciprocation 50 times / minute and a stroke of 5 cm on a cotton ball (melt) moistened with 99.5% purity ethanol, and then whitening, gloss change and abnormality of the coating film were confirmed.

12) Cross cutting film adhesion

Cross-cutting film adhesion evaluation was carried out in 11 x 1mm intervals each transverse x length, and after the Scotch tape was completely adhered, and then peeled off rapidly in the 90 ° direction, the adhesion state of the printing and coating film was confirmed.

(2) Review  Evaluation results

Table 3 shows the results of evaluation of the properties of the Examples and Comparative Examples 1 and 2.

[Table 3]

ΔL = monochrome difference, ΔE = color difference, ΔG = gloss difference

Referring to Table 3, it can be seen that in the case of the embodiment, despite the thickness of the coating film is reduced by 50% or more, the corrosion resistance, high temperature, high humidity, conductivity, and the like of the comparative example are almost the same.

As a result, the black resin steel sheet for backer of the flat panel display device according to the present invention having the above-described physical properties can be manufactured in an ultra-thin plate shape compared to the conventional back cover, but has the advantage of maintaining the conventional physical properties as it is. In addition, the coating amount can be reduced by making the thickness of the coating film thin.

Although the above description has been made with reference to the embodiments of the present invention, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible.

Therefore, the true technical protection scope of the present invention will be defined by the claims below.

1 shows a back cover of an LED TV and a PDP TV.

2 is a cross-sectional view illustrating a black steel plate for a back cover of a conventional flat display device.

Figure 3 shows a cross-sectional view of the black resin sheet for back cover of the flat panel display device according to the present invention.

Figure 4 shows the embossed pattern of the black resin steel sheet surface.

5 shows the shape of a roll capable of transferring an embossed pattern.

6 is a flowchart illustrating a method of manufacturing a black resin sheet for a back cover of a flat panel display device according to the present invention.

Claims (20)

Base steel plate; A chromium-free pretreatment layer formed on the base steel plate; An undercoat layer formed on the chromium-free pretreatment layer; A top coat layer formed on the bottom coat layer; And And an aqueous inner fingerprint layer formed under the base steel sheet. The undercoat layer is formed to a thickness of 1 ~ 4㎛, the top coat layer is a black resin steel sheet for a back cover of a flat panel display device, characterized in that formed in 5 ~ 10㎛ thickness. The method of claim 1, The black resin steel sheet is a black resin steel sheet for a back cover, characterized in that the embossed pattern is formed to a depth of 1 ~ 200㎛ from the upper surface. The method of claim 1, The base steel sheet is a black resin steel sheet for a back cover of a flat panel display device, characterized in that it has a thickness of 0.3 ~ 0.5mm. The method of claim 3, The chromium-free pretreatment layer is formed to a thickness of 0.05 ~ 0.1 ㎛, The black resinous steel sheet for a back cover of a flat panel display device, characterized in that the water-based fingerprint layer is formed to a thickness of 0.5 ~ 1.5㎛. The method of claim 1, The top coat layer is formed from a composition comprising 1 to 10% by weight of black pigment, 20 to 50% by weight of polyester, 1 to 10% by weight of acrylic beads, 1 to 10% by weight of a matting agent, and the remaining amount of solvent. Black resin sheet for back cover of display device. The method of claim 5, The black pigment is a black resin steel sheet for a back cover of a flat panel display device, characterized in that the carbon black pigment 99.0 ~ 99.9% by weight and the yellow pigment pigment 0.1 ~ 1% by weight. The method of claim 1, The undercoat is formed from a composition comprising 1 to 5% by weight of carbon black, 10 to 30% by weight of polyester, 5 to 10% by weight of rust-preventive pigment, 1 to 5% by weight of rust-preventive aid and the remaining amount of solvent. Black resin sheet for back cover of display device. The method of claim 1, The chromium-free pretreatment layer is formed from a composition comprising 1 to 5% by weight of phosphoric acid, 0.1 to 1% by weight of hydrogen hexafluorozirconate (IV), 1 to 5% by weight of titanium fluoride, and a balance of water. Black resin sheet for back cover of display device. The method of claim 1, The aqueous fingerprint-based resin layer comprises 1 to 10% by weight of acrylic resin, 1 to 10% by weight of urethane resin, 10 to 30% by weight of zirconium oxide, silica 20 to 40% by weight, ethanol 1 to 5% by weight and the balance of water A black resin steel sheet for back cover of a flat panel display, characterized in that formed from the composition. The method of claim 1, The base steel sheet is a black resin paper plate for a back cover of a flat panel display device, characterized in that any one of hot-dip galvanized steel sheet, alloyed hot-dip galvanized steel sheet and electro-galvanized steel sheet. (a) forming a chromium-free pretreatment layer having a thickness of 0.05 to 0.1 μm on top of a 0.3 to 0.5 mm thick base steel sheet; (b) forming an undercoat layer having a thickness of 1 to 4 μm on the chromium-free pretreatment layer; (c) forming a top coat layer having a thickness of 5 to 10 μm on the undercoat layer; And (d) forming an aqueous anti-fingerprint resin layer having a thickness of 0.5 to 1.5 μm under the base steel plate; and a method of manufacturing a black resin steel sheet for a back cover of a flat panel display device The method of claim 11, After the step (c) or (d), further comprising the step of forming an embossed pattern to a depth of 1 ~ 200㎛ from the upper surface of the black resin steel sheet using a roll having a corresponding pattern formed on the surface A black resin steel sheet manufacturing method for a back cover of a flat panel display device. The method of claim 11, The base steel sheet is a method of manufacturing a black resin steel sheet for a back cover of a flat panel display device, characterized in that the zinc or zinc alloy is plated with an adhesion amount of 10 ~ 60g / m ² . The method of claim 11, Step (a) is (a1) applying a composition comprising 1 to 5% by weight of phosphoric acid, 0.1 to 1% by weight of hydrogen hexafluorozirconate (IV), 1 to 5% by weight of titanium fluoride, and a balance of water on the base steel plate; And (A2) step of drying at a temperature of 60 ~ 140 ℃; black resin sheet manufacturing method for a back cover of a flat panel display device comprising a. The method of claim 14, The chromium-free pretreatment layer is a black resin steel sheet manufacturing method for a back cover of a flat panel display device, characterized in that formed with an adhesion amount of 30 ~ 150 mg / m ² . The method of claim 11, Step (b) is (b1) A composition comprising 1 to 5% by weight of carbon black, 10 to 30% by weight of polyester, 5 to 10% by weight of rust preventive pigment, 1 to 5% by weight of rust preventive adjuvant and the remaining amount of solvent on the chromium-free pretreatment layer Applying; And  (b2) drying in a temperature range of 170 ~ 240 ℃; method for manufacturing a black resin steel sheet for a back cover of a flat panel display device comprising a. The method of claim 11, Step (c) is (c1) A composition comprising 1 to 10% by weight of black pigment, 20 to 50% by weight of polyester, 1 to 10% by weight of acrylic beads, 1 to 10% by weight of a matting agent, and a residual amount of solvent is applied onto the undercoat layer. step; And (c2) drying in a temperature range of 170 ~ 250 ℃; method for manufacturing a black resin sheet for a back cover of a flat panel display device comprising a. The method of claim 11, Step (d) (d1) a composition comprising 1 to 10% by weight of acrylic resin, 1 to 10% by weight of urethane resin, 10 to 30% by weight of zirconium oxide, 20 to 40% by weight of silica, 1 to 5% by weight of ethanol and the balance of water Applying the lower portion of the base steel sheet; And (d2) drying in a temperature range of 170 ~ 240 ℃; method for manufacturing a black resin steel sheet for a back cover of a flat panel display device comprising a. The method of claim 18, The aqueous fingerprint-resistant resin layer is a manufacturing method of the black resin sheet for a back cover of a flat panel display device, characterized in that formed with an adhesion amount of 950 ~ 1050mg / m ² . The method of claim 11, Step (a) to step (d) is a black resin steel sheet manufacturing method for a back cover of a flat panel display device, characterized in that the line speed of 50 ~ 150mpm.

Images