CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority and benefit of Korean Patent Application No. 10-2014-0188920, filed on December 24, 2014 with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND
[0002] The present disclosure relates to a low temperature curable anti-corrosion coating composition having a high degree of corrosion resistance, and a zinc-plated steel sheet coated with the low temperature curable anti-corrosion coating composition.
[0003] There has been increasing global interest in environmental problems over the past ten-plus years, and regulations on substances such as heavy metals and halogen compounds causing environmental pollution have been tightened. Typical examples of such regulations are the European Union (EU) directives on Restriction of Hazardous Substances (RoHS) implemented on July 1, 2006; Waste from Electric and Electronic Equipment (WEEE) implemented on July 1, 2006; and End-of-Life Vehicles (ELV) implemented on January 1, 2007. Therefore, a great deal of effort has been made to develop environmentally-friendly products in many industrial fields.
[0004] In the related art, chromate coating films having chromium (Cr) as the main component are formed on zinc-plated (galvanized) steel sheets, zinc alloy plated steel sheets, and aluminum alloy plated steel sheets used for manufacturing automobiles, home appliances, and constructing buildings, so as to improve the corrosion resistance and coating adhesion of the steel sheets.
[0005] However, Cr(III) compounds applied to plating layers of steel sheets are converted into hazardous Cr(VI). Thus, over the past ten-plus years, chromium-free coating compositions have been used for coating steel sheets. Typically, chromium-free coating compositions having a polymer resin such as an acrylic resin or a urethane resin as the main component, a silica sol, and a metal compound inhibitor are used for surface treatment of steel sheets.
[0006] However, such chromium-free coating compositions having a polymer resin and used for coating steel sheets are cured at a relatively high temperature, and thus high-temperature drying equipment is required. However, zinc plating equipment of some steel manufactures is only comprised of a drying apparatus capable of performing a drying process at a temperature of 100°C or lower. Therefore, the development of chromium-free solution compositions curable at a relatively low temperature is required.
[0007] Recently, techniques for treating surfaces of steel sheets with chromium-free coating compositions having silane compounds and curable at a relatively low temperature have been disclosed. However, these techniques do not guarantee sufficient corrosion resistance and have problems related with the solution stability of compositions.

SUMMARY
[0008] Aspects of the present disclosure may provide a low temperature curable anti-corrosion coating composition not containing hazardous chromium, and a zinc-plated steel sheet coated with the anti-corrosion coating composition and having a high degree of corrosion resistance.
[0009] According to an aspect of the present disclosure, a low temperature curable anti-corrosion coating composition having a high degree of corrosion resistance may include: a silane compound in an amount of 5 wt% to 30 wt%, a polysilicate compound in an amount of 1 wt% to 10 wt%, a titanium compound in an amount of 0.1 wt% to 5 wt%, a wax in an amount of 0.l wt% to 5 wt%, an alcohol for low temperature curing in an amount of 1 wt% to 15 wt%, and the balance of a solvent.
[0010] The silane compound may include at least one selected from the group consisting of epoxysilane compounds, aminosilane compounds, hydrolysates thereof, and condensation products of the hydrolysates.
[0011] The silane compound may be a mixture of an aminosilane compound and an epoxysilane compound, and the mixing ratio of the aminosilane compound and the epoxy silane compound may be 1:0.2 to 1:10.
[0012] The silane compound may include at least one selected from the group consisting of vinylmethoxysilane, vinyltrimethoxysilane, vinylepoxysilane, vinyltriepoxysilane, 3-aminopropyltriepoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-metaglycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triepoxysilane)-1-propaneamine, N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine, N-ß(aminoethyl)-?-aminopropyltrimethoxysilane, N-ß(aminoethyl)-?-aminopropyltriethoxysilane, N-ß(aminoethyl)-?-aminopropylmethyltriethoxysilane, N-(ß-aminoethyl)-?-aminopropylmethyldimethoxysilane, N-(ß-aminoethyl)-?-aminopropyltrimethoxysilane, ?-glycidoxypropyltriethoxysilane, ?-glycidoxytrimethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ?-methacryloxypropyltrimethoxysilane, ?-methacryloxypropyltriethoxysilane, ?-mercaptopropyltrimethoxysilane, ?-mercaptopropyltriethoxysilane, and N-[2-(vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane.
[0013] The polysilicate compound may include at least one selected from the group consisting of lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica.
[0014] The titanium compound may include at least one selected from the group consisting of titanium carbonate, isopropyl ditriethanolamino titanate, lactic acid titanium chelate, and titanium acetylacetonate.
[0015] The wax may include polyethylene, polytetrafluoroethylene, or a mixture thereof.
[0016] The alcohol for low temperature curing may include at least one selected from the group consisting of ethanol, propanol, and isopropanol.
[0017] According to another aspect of the present disclosure, a zinc-plated steel sheet having a high degree of corrosion resistance may include: a steel sheet; a zinc plating layer formed on one or both sides of the steel sheet; and a coating layer formed on the zinc plating layer, wherein the coating layer may be a cured product of the anti-corrosion coating composition.
[0018] The anti-corrosion coating composition may have a curing temperature within a range of 50°C to 150°C.
[0019] The coating layer may have a weight of 0.05 g/m2 to 2.0 g/m2 in a dried state.
[0020] The zinc plating layer may include an electro-zinc plating layer, a hot-dip zinc plating layer, a hot-dip alloyed zinc plating layer, or an aluminum-zinc alloy plating layer.

BRIEF DESCRIPTION OF DRAWINGS
[0021] The above and other aspects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic cross-sectional view illustrating a zinc-plated steel sheet coated with an anti-corrosion coating composition according to an exemplary embodiment of the present disclosure;
FIG. 2 is a view illustrating pictures of cups of examples and comparative examples after a fuel resistance test.
FIG. 3 is a graph illustrating the range of seam welding current for steel sheets of examples and comparative examples; and
FIG. 4 is a view illustrating pictures of steel sheets of examples and comparative examples after a corrosion resistance test.

DETAILED DESCRIPTION
[0022] Hereinafter, embodiments of the present inventive concept will be described as follows with reference to the attached drawings.
[0023] The present inventive concept may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
[0024] Throughout the specification, it will be understood that when an element, such as a layer, region or wafer (substrate), is referred to as being “on,” “connected to,” or “coupled to” another element, it can be directly “on,” “connected to,” or “coupled to” the other element or other elements intervening therebetween may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element, there may be no elements or layers intervening therebetween. Like numerals refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
[0025] It will be apparent that though the terms first, second, third, etc. may be used herein to describe various members, components, regions, layers and/or sections, these members, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section discussed below could be termed a second member, component, region, layer or section without departing from the teachings of the exemplary embodiments.
[0026] Spatially relative terms, such as “above,” “upper,” “below,” and “lower” and the like, may be used herein for ease of description to describe one element’s relationship to another element(s) as shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “above,” or “upper” other elements would then be oriented “below,” or “lower” the other elements or features. Thus, the term “above” can encompass both the above and below orientations depending on a particular direction of the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.
[0027] The terminology used herein is for describing particular embodiments only and is not intended to be limiting of the present inventive concept. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, members, elements, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, elements, and/or groups thereof.
[0028] Hereinafter, embodiments of the present inventive concept will be described with reference to schematic views illustrating embodiments of the present inventive concept. In the drawings, for example, due to manufacturing techniques and/or tolerances, modifications of the shape shown may be estimated. Thus, embodiments of the present inventive concept should not be construed as being limited to the particular shapes of regions shown herein, for example, to include a change in shape results in manufacturing. The following embodiments may also be constituted by one or a combination thereof.
[0029] The contents of the present inventive concept described below may have a variety of configurations and propose only a required configuration herein, but are not limited thereto.
[0030] An exemplary embodiment of the present disclosure provides a low temperature curable anti-corrosion coating composition having a high degree of corrosion resistance. In detail, the low temperature curable anti-corrosion coating composition includes: a silane compound in an amount of 5 wt% to 30 wt%, a polysilicate compound in an amount of 1 wt% to 10 wt%, a titanium compound in an amount of 0.1 wt% to 5 wt%, a wax in an amount of 0.l wt% to 5 wt%, an alcohol for low temperature curing in an amount of 1 wt% to 15 wt%, and the balance of a solvent.
[0031] The silane compound may include at least one selected from the group consisting of epoxysilane compounds, aminosilane compounds, hydrolysates thereof, and condensation products of the hydrolysates. The hydrolysates may be silanol compounds obtainable through hydrolysis of silane compounds, and the condensation products may be oligomers obtainable through condensation of the hydrolysates.
[0032] In the exemplary embodiment of the present disclosure, preferably, the content of the silane compound may be within the range of 5 wt% to 30 wt%, and more preferably within the range of 5 wt% to 20 wt%, based on the total weight, 100 wt%, of the anti-corrosion coating composition. If the content of the silane compound is less than 5 wt%, corrosion resistance and workability may not be sufficiently improved. If the content of the silane compound is greater than 30 wt%, it may be difficult to prepare the anti-corrosion coating composition, and the solution stability of the anti-corrosion coating composition may be lowered.
[0033] The silane compound may be a mixture of an aminosilane compound and an epoxysilane compound. In this case, the mixing ratio of the aminosilane compound and the epoxysilane compound may preferably be within the range of 1:0.2 to 1:10, and more preferably within the range of 1:0.5 to 1:4.3. If the amount of the epoxysilane composition is less than 0.2 times the amount of the aminosilane compound, reaction in the aminosilane compound may increase because the amount of the aminosilane compound is excessively large, and thus the properties of a coating layer may deteriorate. Conversely, if the amount of the epoxysilane composition is greater than 10 times the amount of the aminosilane compound, reaction in the epoxysilane compound may increase because the amount of the epoxysilane compound is excessively large, and thus the properties of a coating layer may deteriorate.
[0034] In the exemplary embodiment of the present disclosure, the silane compound of the low temperature curable anti-corrosion coating composition having a high degree of corrosion resistance may include, but is not limited to, at least one selected from the group consisting of vinylmethoxysilane, vinyltrimethoxysilane, vinylepoxysilane, vinyltriepoxysilane, 3-aminopropyltriepoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-metaglycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triepoxysilane)-1-propaneamine, N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine, N-ß(aminoethyl)-?-aminopropyltrimethoxysilane, N-ß(aminoethyl)-?-aminopropyltriethoxysilane, N-ß(aminoethyl)-?-aminopropylmethyltriethoxysilane, N-(ß-aminoethyl)-?-aminopropylmethyldimethoxysilane, N-(ß-aminoethyl)-?-aminopropyltrimethoxysilane, ?-glycidoxypropyltriethoxysilane, ?-glycidoxytrimethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ?-methacryloxypropyltrimethoxysilane, ?-methacryloxypropyltriethoxysilane, ?-mercaptopropyltrimethoxysilane, ?-mercaptopropyltriethoxysilane, and N-[2-(vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane.
[0035] For example, the polysilicate compound of the anti-corrosion coating composition may include, but is not limited to, at least one selected from the group consisting of lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica. The content of the polysilicate compound may preferably be within the range of 1 wt% to 10 wt%, and more preferably within the range of 2 wt% to 8 wt%. If the content of the polysilicate compound is less than 1 wt%, it may be difficult to obtain sufficient corrosion resistance. Conversely, if the content of the polysilicate compound is greater than 10 wt%, a fragile coating layer may be formed, and the solution stability of the anti-corrosion coating composition may be lowered.
[0036] The titanium compound of the anti-corrosion coating composition of the exemplary embodiment may facilitate the crosslinking reaction of a coating layer and improve adhesion of the coating layer. The titanium compound may include, but is not limited to, at least one selected from the group consisting of titanium carbonate, isopropyl ditriethanolamino titanate, lactic acid titanium chelate, and titanium acetylacetonate. Preferably, the content of the titanium compound may be within the range of 0.1 wt% to 5 wt%. If the content of the titanium compound is less than 0.1 wt%, a crosslinking reaction may incompletely occur, and insufficient corrosion resistance may be obtained. Conversely, if the content of the titanium compound is greater than 5 wt%, the solution stability of the anti-corrosion coating composition may be lowered.
[0037] In the exemplary embodiment of the present disclosure, the anti-corrosion coating composition may include a wax compound. The wax compound may include, but is not limited to, polyethylene, polytetrafluoroethylene, or a mixture thereof. Preferably, the content of the wax compound may be within the range of 0.1 wt% to 5 wt%. If the content of the wax compound is less than 0.1 wt%, the lubricating function of the wax compound may be insufficient, and if the content of the wax compound is greater than 5 wt%, the surface quality of a steel sheet coated with the anti-corrosion coating composition may be poor.
[0038] In addition, the anti-corrosion coating composition may include an alcohol for low temperature curing so as to improve properties related to a low temperature drying process and a waiting period. The alcohol for low temperature curing may include, but is not limited to, at least one selected from the group consisting of ethanol, propanol, and isopropanol. The content of the alcohol for low temperature curing may preferably be within the range of 1 wt% to 15 wt%. If the content of the alcohol is less than 1 wt%, a coating layer may not be completely dried at a low temperature. Conversely, if the content of the alcohol is greater than 15 wt%, solid portions of a coating layer may be markedly varied due to evaporation of the alcohol in a coating layer curing process.
[0039] Another exemplary embodiment of the present disclosure provides a zinc-plated (galvanized) steel sheet having a high degree of corrosion resistance. The zinc-plated steel sheet includes a steel sheet, a zinc plating layer formed on one or both sides of the steel sheet, and a coating layer formed on the zinc plating layer. The coating layer is a cured product of the above-described anti-corrosion coating composition.
[0040] Preferably, in a dried state, the coating layer may have a weight within the range of 0.05 g/m2 to 2.0 g/m2, and more preferably within the range of 0.1 g/m2 to 1.0 g/m2. If the weight of the coating layer is less than 0.05 g/m2, the coating layer may not have a sufficient degree of resistance to corrosion and fuel, and if the weight of the coating layer is greater than 2.0 g/m2, the insulation ability of the coating layer may increase to result in poor weldability. The zinc plating layer may include an electro-zinc plating layer, a hot-dip zinc plating layer, a hot-dip alloyed zinc plating layer, or an aluminum-zinc alloy plating layer.
[0041] In the exemplary embodiment of the present disclosure, the zinc-plated steel sheet having a high degree of corrosion resistance may be manufactured by coating the zinc plating layer with the above-described anti-corrosion coating composition, and curing the anti-corrosion coating composition to form the coating layer.
[0042] The coating may be performed by a method selected from the group consisting of a roll coating method, a casting method, a screen printing method, a spraying method, a gravure coating method, and a dipping method. Although the coating is not limited to the listed coating methods, the coating may be performed by the roll coating method. When the anti-corrosion coating composition is applied to a zinc-plated steel sheet by the roll coating method to form a coating layer, the weight of the coating layer may preferably be adjusted to be within the range of 0.05 g/m2 to 2.0 g/m2 after the coating layer is dried.
[0043] The anti-corrosion coating composition may have a curing temperature within the range of 50°C to 150°C. If the curing temperature of the anti-corrosion coating composition is lower than 50°C, organic and inorganic compositions may insufficiently undergo a curing reaction, and thus corrosion resistance and fuel resistance may not be guaranteed. Conversely, if the curing temperature of the anti-corrosion coating composition is higher than 150°C, a crosslinking reaction being a selective reaction between the aminosilane compound and the epoxysilane compound may decrease, and thus a relatively hard coating layer may be formed to result in poor workability.
[0044] Hereinafter, the present disclosure will be described more specifically through examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.
EXAMPLES
[0045] Commercially available electrogalvanized (EG) steel sheets, galvannealed (GA) steel sheets, and galvanized (GI) steel sheets were used. The EG steel sheets had a plating weight within the range of 10 g/m2 to 40 g/m2. The GA steel sheets had a plating weight of 20 g/m2 to 60 g/m2, and the content of iron (Fe) in plating layers of the GA steel sheets was from 7% to 15%. In addition, the GI steel sheets had a plating weight of 40 g/m2 to 200 g/m2.

[Example 1]
[0046] An anti-corrosion coating composition was prepared as follows. 3 wt% 3-glycidoxypropyltrimethoxysilane (epoxysilane compound) was mixed with 7 wt% N-ß(aminoethyl)-?-aminopropyltrimethoxysilane (aminosilane compound) based on the total weight, 100 wt%, of the anti-corrosion coating composition, and the mixture was hydrolyzed. Thereafter, 3 wt% lithium polysilicate was dissolved in the hydrolyzed mixture, and the mixture was agitated for 30 minutes. Finally, 3 wt% isopropyl ditriethanolamino titanate, 1 wt% polytetrafluoroethylene (PTFE) wax, 3 wt% isopropyl alcohol for low temperature drying, and pure water were added to the mixture, and the mixture was agitated at room temperature with a speed of 100 rpm for 30 minutes.

[Examples 2 to 12]
[0047] Anti-corrosion coating compositions having component contents as illustrated in Table 1 were prepared in the same manner as in Example 1.

[Comparative Examples 1 to 3]
[0048] Anti-corrosion coating compositions having component contents as illustrated in Table 1 were prepared in the same manner as in Example 1.
[0049] The solution stability, fuel resistance, corrosion resistance, and seam weldability of the anti-corrosion coating compositions of Examples 1 to 12 and Comparative Examples 1 to 3 were evaluated as illustrated in Table 1.

[0050] The anti-corrosion coating compositions of Examples 1 to 12 and Comparative Examples 1 to 3 were stored for one week in a constant temperature device maintained at a temperature of 60°C, and then the viscosity and gelation of the anti-corrosion coating compositions and precipitation in the anti-corrosion coating compositions were observed and evaluated as follows.
?: Viscosity increase, gelation, and precipitation were not observed.
?: Increase of viscosity by 4% or more was observed.
?: Increase of viscosity by 10% or more was observed.
×: Viscosity increase, gelation, and precipitation were observed.

[0051] A fuel resistance test was performed using degraded gasoline, bioethanol, degraded diesel, and biodiesel. Composite coated steel sheets were obtained by coating the steel sheets with the anti-corrosion coating compositions of the examples and the comparative examples. Then, samples of the composite coated steel sheets were formed as cups (blank size: 115 mm x 15 mm, cup size data: 50 mm diameter punch, 30 mm deep drawing, punch R = die R = 6R), and then the cups were filled with fuels and covered with glass plates using O-rings. Then, the fuel resistance of the cups was evaluated.
[0052] In detail, the degraded gasoline prepared by adding 5 wt% pure water and 20 ppm formic acid to gasoline was provided in cups, and the cups were maintained at 60°C for 1,000 hours while being shaken at a rate of 60 cycles per minute. Thereafter, corrosion of the cups (steel sheets) was evaluated. The bioethanol prepared by adding 20 wt% bioethanol, 5 wt% pure water, and 20 ppm formic acid to gasoline was provided in cups, and the cups were maintained at 60°C for 1,000 hours while being shaken at a rate of 60 cycles per minute. Thereafter, corrosion of the cups (steel sheets) was evaluated.
[0053] The degraded diesel prepared by adding 5 wt% pure water and 20 ppm formic acid to diesel was provided in cups, and the cups were maintained at 90°C for 8 weeks while being shaken at a rate of 60 cycles per minute. Thereafter, corrosion of the cups (steel sheets) was evaluated. The biodiesel prepared by adding 20 wt% biodiesel, 5 wt% pure water, and 20 ppm formic acid to diesel was provided in cups, and the cups were maintained at 90°C for 8 weeks while being shaken at a rate of 60 cycles per minute. Thereafter, corrosion of the cups (steel sheets) was evaluated.
[0054] FIG. 2 is a view illustrating pictures of cups of examples and comparative examples after the fuel resistance test. Fuel resistance was evaluated as follows.
? corroded area ratio: 0%
? corroded area ratio: less than 5%
? corroded area ratio: 5% to 30%
× corroded area ratio: greater than 30%


[0055] The corrosion resistance of the composite coated steel sheets was evaluated by maintaining the composite coated steel sheets for 480 hours under the conditions of a salt content of 5%, a temperature of 35°C, and a spraying pressure of 1 kg/cm2, and measuring the areas of red rust on the composite coated steel sheets. FIG. 4 is a view illustrating pictures of steel sheets of examples and comparative examples after the corrosion resistance test.
? corroded area ratio: 0%
? corroded area ratio: less than 5%
? corroded area ratio: 5% to 30%
× corroded area ratio: greater than 30%


[0056] The seam weldability of the composite coated steel sheets was evaluated by welding the composite coated steel sheets using an Ironman welding machine (inverter DC seam welding machine) under the conditions of a pressing force of 4 kN, a welding rate of 3 mpm, and a current application time of 33 ms and a rest time of 10 ms, and determining whether weld zones had a constant degree of strength without spatters. Welding current ranges in which the composite coated steel sheets could be welded as described above were used as evaluation criteria. FIG. 3 is a graph illustrating the range of seam welding current for examples and comparative examples.
?: 1.5 kA or greater
?: 1.0 kA to less than 1.5 kA
? : less than 1.0 kA

[Table 1]
No. Composition (wt%) SS CT (°C) CW (mg/m2) Fuel Resistance CR SW
SC PSC TC Wax Alcohol
DG DD BE BD
E1 10 3 3 1 3 ? 120 400 ? ? ? ? ? ?
E2 10 5 2 0.5 5 ? 100 600 ? ? ? ? ? ?
E3 10 7 1 0.1 7 ? 80 800 ? ? ? ? ? ?
E4 10 3 3 1 3 ? 80 400 ? ? ? ? ? ?
E5 10 5 2 0.5 5 ? 100 600 ? ? ? ? ? ?
E6 10 7 1 0.1 7 ? 120 800 ? ? ? ? ? ?
E7 10 3 3 1 3 ? 100 400 ? ? ? ? ? ?
E8 10 5 2 0.5 5 ? 80 600 ? ? ? ? ? ?
E9 10 7 1 0.1 7 ? 120 800 ? ? ? ? ? ?
E10 10 3 3 1 3 ? 100 400 ? ? ? ? ? ?
E11 10 5 2 0.5 5 ? 120 600 ? ? ? ? ? ?
E12 10 7 1 0.1 7 ? 80 800 ? ? ? ? ? ?
CE1 AR 10 SSol 5 2 0.5 3 ? 100 700 ? ? ? ? ? ?
CE2 1 1 5 ? 80 900 ? ? ? ? ? ?
CE3 3 0.1 7 ? 120 1100 ? ? ? ? ? ?
E: example, CE: comparative example, SC: silane compound, AR: acrylic resin, PSC: polysilicate compound, SSol: silica sol, TC: titanate compound, SS: solution stability, CT: curing temperature, CW: coating weight, DG: degraded gasoline, DD: degraded diesel, BE: bioethanol, BD: biodiesel, CR: corrosion resistance, SW: seam weldability

[0057] Organic-inorganic composite compositions of the anti-corrosion coating compositions of Examples 1 to 12 had undergone a curing reaction to an intended degree even at a curing temperature of 80°C to 120°C. Therefore, as illustrated in Table 1, the anti-corrosion coating compositions of Examples 1 to 12 had high fuel resistance, corrosion resistance, and seam weldability.
[0058] The curing reaction of an acrylic resin included in the anti-corrosion coating compositions of Comparative examples 1 to 3 was not complete at a curing temperature of 80°C to 120°C, and thus it was considered that the anti-corrosion coating compositions of Comparative Examples 1 to 3 had poor corrosion resistance, fuel resistance, and seam weldability.
[0059] As set forth above, according to exemplary embodiments of the present disclosure, the anti-corrosion coating composition for coating steel sheets does not contain hazardous chromium, and thus is not harmful to humans. In addition, the anti-corrosion coating composition has a high degree of solution stability and a low curing temperature, and thus the anti-corrosion coating composition may be suitable for a surface treatment process. Furthermore, steel sheets treated with the anti-corrosion coating composition have high corrosion resistance and seam weldability.
[0060] While exemplary embodiments have been illustrated and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present invention as defined by the appended claims.

Claims:We Claim:
1. A low temperature curable anti-corrosion coating composition having a high degree of corrosion resistance, the anti-corrosion coating composition comprising: a silane compound in an amount of 5 wt% to 30 wt%, a polysilicate compound in an amount of 1 wt% to 10 wt%, a titanium compound in an amount of 0.1 wt% to 5 wt%, a wax in an amount of 0.l wt% to 5 wt%, an alcohol for low temperature curing in an amount of 1 wt% to 15 wt%, and the balance of a solvent.

2. The anti-corrosion coating composition of claim 1, wherein the silane compound comprises at least one selected from the group consisting of epoxysilane compounds, aminosilane compounds, hydrolysates thereof, and condensation products of the hydrolysates.

3. The anti-corrosion coating composition of claim 1, wherein the silane compound is a mixture of an aminosilane compound and an epoxysilane compound, and the mixing ratio of the aminosilane compound and the epoxy silane compound is 1:0.2 to 1:10.

4. The anti-corrosion coating composition of claim 1, wherein the silane compound comprises at least one selected from the group consisting of vinylmethoxysilane, vinyltrimethoxysilane, vinylepoxysilane, vinyltriepoxysilane, 3-aminopropyltriepoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-metaglycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triepoxysilane)-1-propaneamine, N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine, N-ß(aminoethyl)-?-aminopropyltrimethoxysilane, N-ß(aminoethyl)-?-aminopropyltriethoxysilane, N-ß(aminoethyl)-?-aminopropylmethyltriethoxysilane, N-(ß-aminoethyl)-?-aminopropylmethyldimethoxysilane, N-(ß-aminoethyl)-?-aminopropyltrimethoxysilane, ?-glycidoxypropyltriethoxysilane, ?-glycidoxytrimethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ?-methacryloxypropyltrimethoxysilane, ?-methacryloxypropyltriethoxysilane, ?-mercaptopropyltrimethoxysilane, ?-mercaptopropyltriethoxysilane, and N-[2-(vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane.

5. The anti-corrosion coating composition of claim 1, wherein the polysilicate compound comprises at least one selected from the group consisting of lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica.

6. The anti-corrosion coating composition of claim 1, wherein the titanium compound comprises at least one selected from the group consisting of titanium carbonate, isopropyl ditriethanolamino titanate, lactic acid titanium chelate, and titanium acetylacetonate.

7. The anti-corrosion coating composition of claim 1, wherein the wax comprises polyethylene, polytetrafluoroethylene, or a mixture thereof.

8. The anti-corrosion coating composition of claim 1, wherein the alcohol for low temperature curing comprises at least one selected from the group consisting of ethanol, propanol, and isopropanol.

9. A zinc-plated steel sheet having a high degree of corrosion resistance, the zinc-plated steel sheet comprising:
a steel sheet;
a zinc plating layer formed on one or both sides of the steel sheet; and
a coating layer formed on the zinc plating layer,
wherein the coating layer is a cured product of the anti-corrosion coating composition of any one of claims 1 to 8.

10. The zinc-plated steel sheet of claim 9, wherein the anti-corrosion coating composition has a curing temperature within a range of 50°C to 150°C.

11. The zinc-plated steel sheet of claim 9, wherein the coating layer has a weight of 0.05 g/m2 to 2.0 g/m2 in a dried state.

12. The zinc-plated steel sheet of claim 9, wherein the zinc plating layer comprises an electro-zinc plating layer, a hot-dip zinc plating layer, a hot-dip alloyed zinc plating layer, or an aluminum-zinc alloy plating layer.