Title of Invention: Coating composition for electro-galvanized steel sheet with excellent heat resistance and tape adhesion, surface-treated steel sheet using the same, and method for manufacturing the same
technical field
[One]
The present invention relates to a coating composition for an electrogalvanized steel sheet having excellent heat resistance and tape adhesion, a steel sheet surface-treated using the same, and a method for manufacturing the same.
[2]
background
[3]
Electrogalvanized steel sheet is widely used as a chassis of video home appliances and exterior panels of home appliances. In the past, the method of fixing parts to the chassis using bolts for fixing wires and other accessories after press machining of the video home appliance chassis has been performed. Most of them are being converted to the way they are used.
[4]
[5]
On the other hand, until now, the surface treatment of electrogalvanized steel sheet has been using silica together with polyolefin resin or water dispersion type urethane resin having a high acid value. has been used
[6]
[7]
However, polyolefin resins with high acid values ​​or water-dispersible urethane resins have a disadvantage in that they do not have good adhesion to the double-sided tape used for fixing the chassis. There is a problem in that the heat resistance of the unpainted part is low and yellowing occurs.
[8]
[9]
For example, as in Patent Publication No. 2010-0026125, a technology for adhering a steel sheet using an adhesive tape has been studied, but research on a technology for improving the tape adhesion of the coating layer of the steel sheet itself is insufficient.
[10]
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[11]
An object of the present invention is to provide a coating composition for an electrogalvanized steel sheet having excellent heat resistance, corrosion resistance and chemical resistance as well as excellent adhesion to a tape used for a chassis.
[12]
means of solving the problem
[13]
According to one aspect of the present invention, the present invention is a silane; silica sol; polyurethane resin, acrylic emulsion resin, or a mixture thereof; anti-corrosion additives; and water, wherein the silane provides a coating composition for an electrogalvanized steel sheet comprising a tetrafunctional silane and a trifunctional silane.
[14]
[15]
According to another aspect of the present invention, the present invention is an electro-galvanized steel sheet; and a coating layer formed by coating and curing the coating composition for an electrogalvanized steel sheet of the present invention on the steel sheet.
[16]
[17]
According to another aspect of the present invention, the present invention provides a method for manufacturing an electrogalvanized steel sheet, comprising the step of coating the coating composition for an electrogalvanized steel sheet of the present invention on one surface of the electrogalvanized steel sheet.
[18]
Effects of the Invention
[19]
The coating composition for an electrogalvanized steel sheet of the present invention has excellent adhesion to the plating layer formed on the surface of the steel sheet, and further has excellent heat resistance, corrosion resistance and chemical resistance, as well as excellent adhesion to a tape used for a chassis, and The above properties can be imparted by forming and drying the coating layer once without forming and drying the coating layer.
[20]
Brief description of the drawing
[21]
1 is a graph of the heat resistance evaluation results of Examples and Comparative Examples.
[22]
2 is a graph of the evaluation results of tape adhesion of Examples and Comparative Examples.
[23]
Best mode for carrying out the invention
[24]
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.
[25]
[26]
An object of the present invention is to provide a coating composition for an electrogalvanized steel sheet having excellent heat resistance, corrosion resistance and chemical resistance as well as excellent adhesion to a tape used for a chassis.
[27]
[28]
In detail, the present invention is silane; silica sol; polyurethane resin, acrylic emulsion resin, or a mixture thereof; additives for corrosion protection; and water, wherein the silane is to provide a coating composition for an electrogalvanized steel sheet comprising a tetrafunctional silane and a trifunctional silane.
[29]
[30]
In more detail, the present invention is based on the total weight of the coating composition for an electrogalvanized steel sheet, silane is 5 to 20% by weight; 2 to 10% by weight of silica sol; 10 to 50% by weight of polyurethane resin, acrylic emulsion resin, or a mixture thereof; Anti-corrosion additive 0.1 to 2.0% by weight; And to provide a coating composition for an electrogalvanized steel sheet comprising the remainder of water.
[31]
[32]
The silane serves to bond the steel sheet and silica or silica, and serves to increase tape adhesion of the coating layer formed on the steel sheet. The silane is included in an amount of 5 to 20% by weight based on the total weight of the coating composition for an electrogalvanized steel sheet, and when it is less than 5% by weight, the overall physical properties such as heat resistance, solvent resistance, chemical resistance, and tape negligence of the coating layer are reduced, 20 When more than % by weight is added, the hardness of the coating layer increases and cracks are generated on the surface of the coating layer, so that corrosion resistance and corrosion resistance of the processing part become weak.
[33]
[34]
Further, the silane is tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, decyltri Methoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4 epoxy cyclohexyl)-ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl Methyldiethoxysilane, 3-glycidoxy propyltriethoxysilane, 3-methacryloxy propylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3 -Methacryloxypropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl methyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, N-(2 -Aminoethyl)-3-aminopropyl triethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxy silane, 3-Uredopropyltrialkoxysilane, 3-isocyanatepropyl At least one selected from the group consisting of triethoxysilane (3-Isocynatepropyltriethoxy silane), and tris- (trimethoxysilylpropyl) isocyanurate may be used, but is limited thereto No, when two or more are used, two or more silanes may be a hydrolysis-condensation product.
[35]
[36]
Preferably, in order to improve the adhesiveness of the tape, it is preferable to use one or a mixture of two or more silanes of an epoxy group, an amino group, an isocyanate group, and a ureido group, for example. 3-Glycidoxypropyl trimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane , N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-amino Propyltriethoxy silane, 3-Uredopropyltrialkoxysilane, 3-Isocynatepropyltriethoxy silane, and tris-(trimethoxysilylpropyl)isocyanurate (Tris) -(trimethoxysilylpropyl)isocyanurate) can be used to improve tape adhesion by using two or more silanes.
[37]
[38]
Furthermore, it is preferable to use a mixture of tetrafunctional silane and trifunctional silane as the silane of the present invention. When the coating layer is formed using only the tetrafunctional silane, the organic functional group of the silane does not exist, resulting in poor tape adhesion, and furthermore, the hardness of the coating layer is increased and the final coating layer is easily broken. In addition, the molecular weight of the solution is maximized, which may cause a problem of poor stability of the solution. On the other hand, when only the trifunctional silane is used, the drying speed and the post-curing speed are significantly lowered, which causes the composition to be smeared on the roll during roll coating. As a result, it is easy to cause a blocking phenomenon during stacking.
[39]
[40]
However, when the tetrafunctional silane and the trifunctional silane are mixed and used, the content of the trifunctional silane is preferably greater than the content of the tetrafunctional silane. This is because, when the content of the tetrafunctional silane is greater than that of the trifunctional silane, the organic functional groups decrease and the adhesiveness of the tape may be easily deteriorated.
[41]
[42]
The trifunctional silane may have a structural formula of X-Si-(OR) 3 (wherein X is a vinyl group (Vinyl), an epoxy group (Epoxy), an amino group (Amino), a methacryloxy group (Methacryloxy), or a mecap May be any one of earthenware (Mercapto), R may be any one of hydrogen, methyl (Methyl), ethyl (Ethyl), or propyl (Propyl)), in the structural formula, X group is the resin and organic component of the coating layer may play a role in improving the adhesion of the coating layer and the adhesion of the tape by inducing a chemical bond of
[43]
[44]
On the other hand, the silica sol is used to enhance the corrosion resistance of the steel sheet and the stability of the coating composition. The silica sol may be used in an amount of 2 to 10% by weight based on the total weight of the coating composition for an electrogalvanized steel sheet, and when it is less than 2% by weight, the corrosion resistance and stability of the coating composition decrease, and when it exceeds 10% by weight The chemical resistance and workability of the coating layer formed by the composition are lowered, and problems such as film removal of the coating layer in the degreasing process during material processing are likely to occur, and the coating layer may be broken during processing of the steel sheet.
[45]
[46]
At this time, the silica sol may be a silica sol in which nano-sized silica is dispersed in water, and when nano-sized silica is used, the stability of the solution, the corrosion resistance of the finally formed coating layer, and the scratch resistance of the coating layer can be improved, for example. For example, nano silica having an average particle diameter of 5 to 20 nm may be used.
[47]
[48]
Furthermore, the silica sol may be an acidic silica sol, and when the silica sol is basic, there may be a problem in that it is difficult to proceed with a sol-gel reaction through a hydrolysis condensation reaction of silane.
[49]
[50]
At this time, the silane crystallization and condensation reaction proceeds as follows in an acidic state at a low temperature.
[51]
(One)
[52]
In detail, as in (1), the oxygen of the alkoxy group attacks the positively charged particles [H 3 O] + in an acidic atmosphere (pH < 2.5).
[53]
(2)
[54]
This can be represented by the reaction formula as in (2), and then a condensation reaction occurs as shown in (3) below.
[55]
(3)
[56]
[57]
As in the reactions of (2) and (3), the condensation reaction of silane proceeds as a Sn2 reaction in two steps, and the hydrolysis reaction occurs faster than the condensation reaction, and the reaction proceeds sequentially. Therefore, in the present invention, it is preferable to use an acidic silica sol for hydrolysis and condensation of silane.
[58]
[59]
On the other hand, the polyurethane resin, acrylic emulsion resin, or a mixture thereof of the present invention may be an aqueous dispersion, through which chemical resistance, corrosion resistance and surface recoatability of the steel sheet can be imparted, and storage stability and mechanical properties of the aqueous solution Cationic or nonionic can be used for characterization. At this time, the polyurethane resin, the acrylic emulsion resin, or a mixture thereof is preferably used in an amount of 10 to 50% by weight, preferably 10 to 30% by weight, based on the total weight of the coating composition for an electrogalvanized steel sheet. When the content is less than 10% by weight, the workability of the coating layer is poor, powdering and material breakage may occur during press work, and the corrosion resistance of the processing part may be weakened, and if it exceeds 50% by weight, heat resistance and tape adhesion And physical properties such as solvent resistance may become weak.
[60]
[61]
Furthermore, the polyurethane resin can be formed by using hydrophilic functional groups such as acrylic polyol, polyethylene polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, etc., diisocyanate, chain extender, and tertiary amine. It can be used by dispersion, and the diisocyanate is p-phenylene diisocyanate, 1,6-hexamethylene diisocyanate, and toluene diisocyanate. ), 1,5-naphthalene diisocyanate, Isophorone diisocyanate, 4,4-Diphenylmethane diisocyanate, and cyclohexyl At least one diisocyanate selected from the group consisting of methane diisocyanate (Cyclohexylmethane diisocyanate). Preferably, the diisocyanate may be an alicyclic diisocyanate to impart heat resistance and UV resistance to the steel sheet.
[62]
[63]
In addition, the polyurethane resin may have a free NCO% of 1 to 5%, preferably 2 to 3%, of the prepolymer when synthesizing a water-dispersible urethane resin in order to impart heat resistance of 250° C. × 1 hour. If the free NCO% exceeds 5%, the urea group of the final water-dispersible polyurethane resin increases and the heat resistance becomes weak. could become vulnerable.
[64]
[65]
Furthermore, the present invention may include an additive for corrosion prevention in order to prevent corrosion of the steel sheet. The anti-corrosion additive may be an organic acid salt, inorganic acid salt or hydroxide of a metal, for example, the anti-corrosion additive is at least one selected from the group consisting of Al, Ti, Mo, V, Mn, Mg, P and Zr. Salts of metals may be used. In addition, for example, the salt may be a phosphate, nitrate, carbonate, acetate or hydroxide, but is not limited thereto, and is preferably used in combination with an inorganic acid salt of Ti, Zr, V, P, and Mo and a phosphate-modified product. can
[66]
[67]
The anti-corrosion additive may be included in an amount of 0.1 to 2% by weight, preferably 0.1 to 1% by weight, based on the total weight of the coating composition for an electrogalvanized steel sheet. When the content of the anti-corrosion additive is less than 0.1% by weight, the effect of improving the corrosion resistance of the steel sheet is insignificant, and when it exceeds 2% by weight, gelation of the coating composition proceeds and solution stability may decrease.
[68]
[69]
Furthermore, the coating composition for an electrogalvanized steel sheet of the present invention may further include an organic solvent, an additive for surface formation, water, and the like.
[70]
[71]
The organic solvent may be used for stability and workability of the solution of the coating composition, for example, alcohols such as methanol, ethanol, isopropanol, N-butanol or ethylene glycol, propylene glycol, butyl cellosolve, ethyl cell A hydrophilic organic solvent such as Losolve, diacetone alcohol, or acetylacetone may be used, but is not limited thereto. The organic solvent may be included in an amount of 5 to 15% by weight, preferably 5 to 10% by weight, based on the total composition. When the organic solvent is included in an amount of less than 5% by weight, the stability of the solution of the coating composition is deteriorated and the drying rate of the solution is slowed down. In addition, when the organic solvent is contained in an amount exceeding 15% by weight, it causes many problems in workability due to the volatilization of the solvent during roll operation, and causes the occurrence of harmful vapors caused by the solvent volatilized during the curing process.
[72]
[73]
Furthermore, as the surface forming additive, an antifoaming agent, a leveling agent, etc. may be added, and 1 to 6 wt%, preferably 1 to 5 wt%, more preferably 1 to 6 wt% based on the total weight of the coating composition for electrogalvanized steel sheet to 2% by weight, and water may be added so that the solid content of the coating composition for an electrogalvanized steel sheet is 5 to 30% by weight. If the solid content is less than 5% by weight, the viscosity may be high and workability may be poor, and if it exceeds 30% by weight, on the contrary, the viscosity may be too low to obtain a target coating film thickness.
[74]
[75]
On the other hand, the present invention provides an electrogalvanized steel sheet having a coating layer formed by the coating composition for an electrogalvanized steel sheet of the present invention.
[76]
[77]
In detail, the present invention is an electro-galvanized steel sheet; and a coating layer formed by coating and curing the coating composition for an electrogalvanized steel sheet of the present invention on the steel sheet, and forming a coating layer without a primer by one coating by application of the composition , at the same time, it is possible to obtain a steel sheet having excellent heat resistance, corrosion resistance, chemical resistance and tape adhesion.
[78]
[79]
On the other hand, the coating layer may be formed to a thickness of 0.1 to 2.0 μm, and when the thickness is less than 0.1 μm, there may be a problem that it cannot exhibit sufficient physical properties, and when it exceeds 2.0 μm, the surface electricity required for the anti-fingerprint steel sheet There may be a problem with poor conductivity. Therefore, 0.5 to 1.5 μm is most preferably suitable for use as a panel for video appliances.
[80]
[81]
Furthermore, the present invention provides a method for manufacturing the electrogalvanized steel sheet.
[82]
[83]
In detail, the present invention provides a method for manufacturing an electrogalvanized steel sheet, comprising coating the coating composition for an electrogalvanized steel sheet of the present invention on one surface of the electrogalvanized steel sheet.
[84]
[85]
The coating may be performed by a coating method such as roll coating or bar coating, but is not limited thereto, and any method may be used as long as it is a method capable of forming a coating layer with a constant thickness.
[86]
[87]
Furthermore, the coating layer may be cured through heat treatment, for example, after the coating step, the step of curing at a temperature of 150 to 180 ℃ may be further performed. At this time, when the temperature of the curing step is less than 150 ° C, sufficient drying does not occur, making it difficult to form a coating film, and when the curing temperature exceeds 180 ° C, sufficient curing occurs but a lot of energy is required. .
[88]
[89]
Hereinafter, the present invention will be described in more detail through specific examples. The following examples are only examples to help the understanding of the present invention, and the scope of the present invention is not limited thereto.
[90]
Modes for carrying out the invention
[91]
[92]
Example
[93]
[94]
Silane was added based on the total weight of the composition to a four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen injector, and acetic acid and silica sol (pH 4, average particle size 12 nm, SiO 2 ) content 20% by weight) and a mixture of ion-exchanged water are slowly added dropwise at room temperature for 2 hours. At this time, pay attention to heat generation, and dropwise while controlling the temperature so that the temperature of the flask does not exceed 30°C.
[95]
[96]
After the dropping is completed, the mixture is stirred at room temperature for 24 hours. From this, a solution containing a transparent copolymer of silica silane was obtained.
[97]
[98]
In the solution, ion-exchanged water, water-dispersed polyurethane resin (solid content 30% by weight), ethanol, a vanadium salt (ammonium metavanadate) and zirconium salt (hexafluorozirconic acid) as a corrosion inhibitor, phosphoric acid, and ethanol as a leveling agent And polysiloxane dimethylpolysiloxane was added as an antifoaming agent, stirred for 30 minutes, and then packaged with a 30 micron filtration filter. Specific components and content of the components of the prepared composition are shown in Table 1 based on the total weight of the composition.
[99]
[Table 1]
[100]
* The balance contains ion-exchanged water.
[101]
* S1) tetraethoxysilane; S2) vinyltriethoxysilane; S3) 3-glycidoxypropyl trimethoxysilane; S4) 3-glycidoxypropyltriethoxysilane; S5) N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; S6) 3-aminopropyltrimethoxysilane; S7) 3-aminopropyltriethoxy silane; S8) 3-Uredopropyltrialkoxysilane; S9) 3-Isocynatepropyltriethoxysilane; R1) cationic water dispersion polyurethane resin (polycarbonate polyol); R2) cationic water-dispersion polyurethane resin (polyester polyol); R3) nonionic water-dispersible polyurethane resin (polycarbonate polyol); R4) Nonionic acrylic emulsion
[102]
[103]
Experimental example
[104]
[105]
On an electrogalvanized steel sheet having a thickness of 0.5 mm, Examples 1-6 and Comparative Examples 1-4 were coated using a bar coater so as to be 20±2 g/m 2 . Heat resistance, corrosion resistance, tape adhesion and chemical resistance of the prepared coated steel sheet were evaluated, and the evaluation method was as follows, and each evaluation result is shown in Table 2.
[106]
[107]
[Heat resistance]
[108]
The heat resistance test was performed at an oven temperature of 250° C. for 1 hour.
[109]
1 = Color difference value (ΔE) less than 5.0 before and after the test
[110]
2 = Color difference value (ΔE) before and after the test 5.0 or more and less than 6.0
[111]
3 = Color difference value (ΔE) before and after the test 6.0 or more and less than 7.0
[112]
4 = Color difference value (ΔE) before and after test 7.0 or more, less than 8.0
[113]
5 = Color difference value (ΔE) before and after test 8.0 or more, less than 9.0
[114]
6 = Color difference value (ΔE) 9.0 or higher before and after the test
[115]
[116]
[Corrosion resistance]
[117]
(1) SST flat part test
[118]
White rust was observed by testing at 5% NaCl, 35°C for 120 hours.
[119]
1 = White rust generation area is less than 5% of the total area
[120]
2 = White rust occurrence area is 5% or more but less than 10% of the total area
[121]
3 = White rust occurrence area is 10% or more but less than 30% of the total area
[122]
4 = White rust generation area is 30% or more but less than 60% of the total area
[123]
5 = White rust occurrence area is more than 60% of the total area
[124]
(2) SST machining part test
[125]
After the Eriksen test (6mm) was performed, the white rust was observed in 5% NaCl, 35°C, for 48 hours.
[126]
1 = White rust generation area is less than 5% of the machining area
[127]
2 = White rust generation area is 5% or more but less than 10% of the area of ​​the machined part
[128]
3 = White rust generation area is 10% or more but less than 30% of the processing area
[129]
4 = White rust generation area is 30% or more and less than 60% of the area of ​​the machined part
[130]
5 = White rust generation area is more than 60% of the area of ​​the machined part
[131]
[132]
[Tape Adhesion (Adhesive)]
[133]
For tape adhesion, 3M's tape was used, and the width of the test tape was 20 mm and the length of the tape was 100 mm. After the test piece was washed with alcohol before the tape was attached, the tape was hung with an 80 g weight and evaluated at room temperature and 60°C. The grade was evaluated by measuring the average of the tape peeling length when the tape was attached at room temperature and 60° C. after 12 days.
[134]
1 = Peel length less than 5mm
[135]
2 = Peeling length 5mm or more and less than 6mm
[136]
3 = Peeling length 6mm or more and less than 7mm
[137]
4 = Peel length 7mm or more, less than 8mm
[138]
5 = Peeling length 8mm or more and less than 10mm
[139]
6 = Peeling length 10mm or more
[140]
[141]
[Chemical resistance]
[142]
For chemical resistance, PALKLIN N364S from Parker Japan, which is a heavy alkali degreasing agent, was used, and a 2% aqueous solution was prepared, the substrate was immersed, and ultrasonic degreasing was performed for 5 minutes.
[143]
1 = 0% of the peeling area of ​​the coating film
[144]
2= ​​More than 0% of the film peeling area, less than 10%
[145]
3= 10% or more, less than 20% of the peeling area of ​​the coating film
[146]
4 = 20% or more, less than 30% of the film peeling area
[147]
5= 30% or more of the coating film peeling area, less than 40%
[148]
6= 40% or more of the film peeling area
[149]
[150]
[Table 2]
[151]
As a result, as shown in Table 2, Examples 1 to 6 showed excellent heat resistance, corrosion resistance, tape adhesion and chemical resistance, whereas Comparative Examples 1 to 4 showed heat resistance, corrosion resistance, tape adhesion and One or more properties of chemical resistance were found to be inferior.
[152]
[153]
In particular, the heat resistance and tape adhesion according to the temperature of Examples 1 and 5 and Comparative Examples 1 and 2 are shown in FIGS. 1 and 2, respectively, and as shown in FIGS. 1 and 2, the composition of the present invention has excellent heat resistance, It was confirmed that the adhesiveness of the tape was maintained even at room temperature and 60°C.
[154]
[155]
Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.
Claims
[Claim 1]
silane; silica sol; polyurethane resin, acrylic emulsion resin, or a mixture thereof; anti-corrosion additives; and water, wherein the silane includes a tetrafunctional silane and a trifunctional silane.
[Claim 2]
According to claim 1, Based on the total weight of the coating composition for electrogalvanized steel sheet, the silane is 5 to 20% by weight; 2 to 10% by weight of the silica sol; 10 to 50% by weight of the polyurethane resin, acrylic emulsion resin, or a mixture thereof; 0.1 to 2.0 wt% of the anti-corrosion additive; and the balance of water, the coating composition for an electrogalvanized steel sheet.
[Claim 3]
According to claim 1, wherein the silane is tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, diphenyldime Toxysilane, decyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4 epoxy cyclohexyl)-ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3 -Glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxy propylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri Methoxysilane, 3-methacryloxypropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl methyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane , N-(2-aminoethyl)-3-aminopropyl triethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxy silane, 3-Uredopropyltrialkoxysilane (3-Uredopropyltrialkoxysilane) , 3-isocyanate propyltriethoxy silane (3-Isocynatepropyltriethoxy silane), and tris- (trimethoxysilylpropyl) isocyanurate (Tris- (trimethoxysilylpropyl) isocyanurate) at least one selected from the group consisting of, the electric A coating composition for a galvanized steel sheet.
[Claim 4]
The coating composition for an electrogalvanized steel sheet according to claim 1, wherein the content of the trifunctional silane is greater than the content of the tetrafunctional silane.
[Claim 5]
The coating composition for an electrogalvanized steel sheet according to claim 1, wherein the silica sol is a silica sol in which nano-sized silica is dispersed in water.
[Claim 6]
The coating composition for an electrogalvanized steel sheet according to claim 1, wherein the silica sol is an acidic silica sol.
[Claim 7]
The coating composition for an electrogalvanized steel sheet according to claim 1, wherein the polyurethane resin or the acrylic emulsion resin is cationic or nonionic.
[Claim 8]
According to claim 1, NCO% of the polyurethane resin is 1 to 5%, the coating composition for an electrogalvanized steel sheet.
[Claim 9]
The coating composition for an electrogalvanized steel sheet according to claim 1, wherein the anticorrosion additive is a salt of one or more metals selected from the group consisting of Al, Ti, Mo, V, Mn, Mg, P and Zr.
[Claim 10]
electro galvanized steel sheet; and a coating layer formed by coating and curing the composition of any one of claims 1 to 6 on the steel sheet.
[Claim 11]
A method of manufacturing an electrogalvanized steel sheet, comprising the step of coating the composition of any one of claims 1 to 7 on one surface of the electrogalvanized steel sheet.
[Claim 12]
The method of claim 11 , further comprising curing at a temperature of 150 to 180° C. after the coating step.