KR20160078773A - Low temperature curable anti-corrosion coating composition excellent in corrosion resistance and zinc plated steel sheet using the same - Google Patents

Abstract

Provided is a low-temperature curable rust proof-coating composition which is an aqueous solution, has excellent corrosion resistance, and contains 5-30 wt% of a silane compound, 1-10 wt% of a polysilicate compound, 0.1-5 wt% of a titanium compound, 0.1-5 wt% of wax, and 1-15 wt% of low-temperature curable alcohol. The composition of the present invention does not contain chrome. Accordingly, the composition is curable at low temperature and safe to human body, while exhibiting outstanding solution stability when carrying out a surface treatment operation. In addition, the steel sheet treated by the composition also shows superior corrosion resistance and seam welding properties.

Description

TECHNICAL FIELD [0001] The present invention relates to a low temperature curing type anticorrosive coating composition having excellent corrosion resistance and a zinc plated steel sheet using the same,

Temperature curing type anticorrosive coating composition excellent in corrosion resistance and a galvanized steel sheet using the same.

Over the past decade, as global environmental concerns have increased, restrictions on the use of environmental pollutants such as heavy metals and organohalogen compounds have been strengthened. In particular, the EU has introduced Restriction of Hazardous Substances (RoHS), Waste Electrical and Electronic Equipment (WEEE) ELV; End-of-Life Vehicles, Jan. 1, 2007). As a result, many efforts have been made to develop eco-friendly products in the industrial field.

Conventionally, a chromate film containing chromium as a main component is coated on the surface of a galvanized steel sheet, a zinc-based alloy coated steel sheet and an aluminum-based alloy coated steel sheet which are used for automobile, home appliance and building applications, and corrosion resistance and paint adhesion are given Respectively.

However, since the Cr (III) compound coated on the surface of the plating layer of the steel sheet is converted into Cr (VI) harmful to human body, it has been converted into a composition for chrome-free steel sheet coating for a decade. Typically, a steel sheet is treated using a composition for steel sheet coating comprising a polymer resin as a main component such as acryl, urethane, etc., and silica sol and a metal compound inhibitor.

However, since a composition for coating a chromium-free steel sheet made of a polymer resin has a high curing temperature and needs to be dried at a high temperature, zinc plating facilities of some steelmakers are composed of drying facilities within 100 ° C, Development of a chromium-free solution composition is required.

On the other hand, recently, a surface treatment technique capable of being cured at a low temperature by treating with a chromium-free steel sheet coating composition containing a silane compound has been disclosed, but the corrosion resistance is poor and the solution stability is poor

The present invention provides a composition for coating a steel sheet which does not contain chromium harmful to the human body and which can be cured at low temperatures, and provides a galvanized steel sheet excellent in corrosion resistance treated with the composition.

According to an embodiment of the present invention, there is provided a process for producing a curable composition comprising 5 to 30 wt% of a silane compound, 1 to 10 wt% of a polysilicate compound, 0.1 to 5 wt% of a titanium compound, 0.1 to 5 wt% of a wax, Curable anti-corrosive coating composition excellent in corrosion resistance.

The silane compound may be at least one selected from an epoxy silane compound, an amino silane compound, a hydrolyzate thereof, and a condensate of the hydrolyzate.

 The silane compound is a mixture of an amino-based silane compound and an epoxy-based silane compound, and the mixing ratio of the amino-based silane compound and the epoxy-based silane compound may be 1: 0.2 to 10.

Wherein the silane compound is selected from the group consisting of vinyl methoxy silane, vinyl trimethoxy silane, vinyl epoxysilane, vinyl triepoxy silane, 3-aminopentyl triethoxy silane, 3-glycidoxypropyl trimethoxy silane, 3- (Triepoxysilane) -1-propanamine, N, N-bis [3- (tri (methoxysilyl) (Aminoethyl) -? - aminopropyltriethoxysilane, N -? (Aminoethyl) -? - aminopropyltrimethoxysilane, N- -aminopropyltrimethoxysilane, N- (? -aminoethyl) -? - aminopropylmethyldimethoxysilane, N- (? -aminoethyl) -? - aminopropyltrimethoxysilane,? - gly Glycidoxytrimethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyl tri (meth) acrylate, Methacryloxypropyltriethoxysilane,? -Mercaptopropyltrimethoxysilane,? -Mercaptopropyltriethoxysilane, and N- [2- (vinylbenzylamino) ethyl] -3 -Aminopropyltrimethoxysilane. ≪ / RTI >

 The polysilicate compound may be at least one selected from lithium polysilicate, sodium polysilicate, potassium polysilicate and colloidal silica.

The titanium compound may be at least one selected from titanium carbonate, isopropyl ditriethanol aminotitanate, titanium lactate lactate, and titanium acetylacetonate.

The wax may be polyethylene, polytetrafluoroethylene or mixtures thereof.

The low-temperature curing alcohol may be at least one selected from ethanol, propanol and isopropanol.

According to another embodiment of the present invention, And a coating layer formed on the zinc plating layer, wherein the coating layer is a cured product of the corrosion inhibiting coating composition, wherein the coating layer is excellent in corrosion resistance.

The rust-inhibiting coating composition may have a curing temperature of from 50 to 150 < 0 > C.

The coating layer may have an adhesion amount of from 0.05 to 2.0 g / m < 2 >

The zinc plated layer may be an electro-galvanized layer, a hot-dip galvanized layer, a galvannealed hot-dip galvanized layer or an aluminum alloy galvanized layer.

The steel sheet coating composition provided by the present invention is harmless to the human body because it does not contain chromium and has excellent solution stability during surface treatment and can be cured at a low temperature. In addition, the steel sheet treated with the composition has an excellent corrosion resistance and core weldability.

1 is a cross-sectional view of a galvanized steel sheet treated with a rust-preventive coating composition according to an embodiment of the present invention.
Fig. 2 is an image for evaluating resistance to fuel for the surface-treated steel sheets of Examples and Comparative Examples.
3 is a graph showing values of seam welding current range for the surface treated steel sheets of Examples and Comparative Examples.
4 is an image for evaluating the corrosion resistance of the surface treated steel sheets of Examples and Comparative Examples.

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

In one embodiment of the present invention, there is provided a low temperature curing type anticorrosive coating composition excellent in corrosion resistance, which comprises 5 to 30 wt% of a silane compound, 1 to 10 wt% of a polysilicate compound, 0.1 to 5 wt% of a titanium compound, 0.1 To 5% by weight of an alcohol for low temperature curing and 1 - 15% by weight of an alcohol for low temperature curing.

The silane compound may be at least one selected from an epoxy silane compound, an amino silane compound, a hydrolyzate thereof, and a condensate of the hydrolyzate. The hydrolyzate is a silanol compound obtained by hydrolyzing a silane compound, and the condensate may be an oligomer produced by the condensation reaction of the hydrolyzate.

The content of the silane compound used in the composition of the present invention is preferably 5 to 30% by weight, more preferably 5 to 20% by weight, based on 100% by weight of the total composition. If the content of the silane compound is less than 5% by weight, the effect of improving the corrosion resistance and processability is insufficient. If the content is more than 30% by weight, the composition is difficult to prepare and the solution stability is deteriorated.

When the silane compound is a mixture of an amino silane compound and an epoxy silane compound, the mixing ratio of the amino silane compound and the epoxy silane compound is preferably 1: 0.2 to 10, more preferably 1: 0.5 to 4.3 desirable. If the content of the epoxy-based silane compound is less than 0.2 times the content of the amino-based silane compound, the reaction between the amino-based silane increases due to the increase of the content of the amino-based silane compound, The reaction between the epoxy silane compounds increases and the physical properties of the coating film may deteriorate.

The silane compound contained in the low temperature curing type anticorrosive coating composition excellent in corrosion resistance of the present invention is not particularly limited, and examples thereof include vinyl methoxy silane, vinyl trimethoxy silane, vinyl epoxysilane, vinyl triepoxy silane, 3- 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N- (1,3-dimethylbutylidene) Propylamine, N, N-bis [3- (trimethoxysilyl) propyl] ethylenediamine, N -? (Aminoethyl) -? - aminopropyltrimethoxysilane, (Aminoethyl) -? - aminopropyltriethoxysilane, N -? - aminopropylmethyltriethoxysilane, N- (? - aminoethyl) -? - aminopropylmethyldimet (? -Aminoethyl) -? - aminopropyltrimethoxysilane,? -Glycidoxypropyltriethoxysilane,? -Glycidoxytrimethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltriethoxysilane,? - May be at least one member selected from the group consisting of mercaptopropyltrimethoxysilane,? -Mercaptopropyltriethoxysilane, and N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane .

The polysilicate compounds included in the composition may be, but are not limited to, one or more selected from lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica. The content of the polysilicate compound is preferably 1 to 10% by weight, more preferably 2 to 8% by weight. When the content of the polysilicate compound is less than 1% by weight, it is difficult to obtain sufficient corrosion resistance. When the content of the polysilicate compound exceeds 10% by weight, the coating film breaks poorly and the stability of the solution deteriorates and the physical properties are significantly deteriorated.

In addition, the titanium compound contained in the composition of the present invention can contribute to accelerating the crosslinking reaction of the coating film and improving the adhesion. The titanium compound may be one or more selected from, but not limited to, titanium carbonate, isopropyl di-triethanol aminotitanate, lactic acid titanium chelate, and titanium acetylacetonate. If the content of the titanium compound is less than 0.1% by weight, the crosslinking reaction is not complete and the corrosion resistance is insufficient. When the content of the titanium compound is more than 5% by weight, the stability of the solution and the physical properties of the coating film It is not preferable.

The composition of the present invention may contain a wax compound to improve the workability of a coating film, and may be polyethylene, polytetrafluoroethylene or a mixture thereof, though not limited thereto. If the amount of the wax compound is less than 0.1% by weight, the lubricating function is not exhibited properly. If the amount of the wax compound is more than 5% by weight, the surface quality of the coated steel sheet .

Further, the composition may contain an alcohol for low-temperature curing in order to improve low-temperature drying and weighting of the composition. The low-temperature curing alcohol may be at least one selected from the group consisting of ethanol, propanol and isopropanol. The content of the low-temperature curable alcohol is preferably 1 to 15% by weight. When the content of the low-temperature curable alcohol is less than 1% by weight, drying is not completed at a low temperature. If the content is more than 12% by weight, There is a severe disadvantage.

According to another embodiment of the present invention, And a coating layer formed on the zinc plating layer, wherein the coating layer is a cured product of the corrosion inhibiting coating composition, wherein the coating layer is excellent in corrosion resistance.

The coating layer preferably has an adhesion amount of the dry film of 0.05 to 2.0 g / m 2, more preferably 0.1 to 1.0 g / m 2. When the adhesion amount is less than 0.05 g / m ² , it is difficult to secure the corrosion resistance and fuel resistance, and when it exceeds 2.0 g / m ^2, the insulation property becomes large and the weldability is deteriorated. Further, the zinc plated layer may be an electro-galvanized layer, a hot-dip galvanized layer, a galvannealed hot-dip galvanized layer or an aluminum alloy galvanized layer.

The zinc-plated steel sheet having excellent corrosion resistance according to the present invention is prepared by coating the above-described rust-preventive coating composition on a zinc-plated layer and curing the coated steel sheet to form a coating layer.

The coating is not limited thereto, but can be carried out by any one method selected from roll coating, casting, screen printing, spraying, gravure coating and immersion, among which the roll coating method is most preferred. When the rust-preventive coating composition is applied to the galvanized steel sheet by the roll coating method, it is preferable to control the adhesion amount of the dry coat to 0.05 to 2.0 g / m 2.

The rust-inhibiting coating composition may have a curing temperature of 50 to 150 ° C. When the curing drying temperature is less than 50 ° C, the curing reaction of the organic-based composition and the inorganic-based composition is insufficient and the effects of corrosion resistance and fuel- , The crosslinking reaction which is a selective reaction between the amino-based silane compound and the epoxy-based silane compound is reduced, resulting in a stiffer coating film, resulting in poor processability.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Commercially available electrogalvanized steel (EG), galvanized steel (GA), galvanized steel (GI) and galvanized steel were used. Wherein the electrogalvanized (EG) steel sheet has a plating adhesion amount of 10 to 40 g / m ² , the galvannealed steel (GA) steel sheet has a plating adhesion amount of 20 to 60 g / m ² , 15%, and the hot-dip galvanized (GI) steel sheet has a coating weight of 40 to 200 g / m ² .

 [Example 1]

3% by weight of 3-glycidoxypropyltrimethoxysilane as an epoxy silane compound and N-beta (aminoethyl) -? - aminopropyltrimethoxysilane as an amino-based silane compound were added to 100% By weight were mixed and hydrolyzed. After dissolving 3% by weight of lithium polysilicate, the mixture was stirred for 30 minutes. Finally, 3% by weight of diisopropyltriethanolamine titanate, 1% by weight of PTFE wax, 3% by weight of isopropyl alcohol for low-temperature drying, and pure water were added to prepare an aqueous solution and further stirred for 30 minutes at a rate of 100 rpm Followed by stirring to prepare a rust-preventive coating composition.

[Example 2-12]

The composition was prepared as in Example 1, with the contents of each component of the composition being adjusted as described in Table 1, for 100 wt.% Of the total composition.

[Comparative Example 1-3]

The composition was prepared as in Example 1, with the contents of each component of the composition being adjusted as described in Table 1, for 100 wt.% Of the total composition.

The metal corrosion inhibiting coating compositions of Examples 1 to 12 and Comparative Examples 1 to 3 were evaluated for corrosion resistance, solution stability, friction characteristics and core weldability against automobile fuel under the following conditions, and the results are shown in Table 1 .

≪ Evaluation of fuel resistance &

The evaluation of fuel resistance was evaluated as fuel resistance with degraded gasoline, deteriorated diesel, bioethanol and biodiesel. The evaluation specimen was filled with cups and filled with o-rings and glass plates after cupping (blank size: 115 × 15 mm; cup size, punch diameter 50 mm, drawing height 30 mm, Punch R = Die R = 6R) Respectively.

The fuel composition of the deteriorated gasoline was as follows: 5 wt% pure water and 20 ppm formic acid were added to ordinary gasoline fuel and allowed to stand for 1000 hours while shaking at a rate of 60 cycles per minute at 60 캜, and then the corrosion state of the steel sheet was evaluated. The fuel composition of the bioethanol was prepared by adding 20 wt% of bioethanol to general gasoline fuel, adding 5 wt% of pure water and 20 ppm of formic acid, shaking at 60 DEG C per minute at a rate of 60 cycles, The corrosion state was evaluated.

In addition, the fuel composition of the deteriorated diesel was evaluated by evaluating the corrosion state of the steel sheet after leaving for 8 weeks while shaking the general diesel fuel at a rate of 5 wt% pure water and 20 ppm formic acid at 90 ° C and 60 cycles per minute. The fuel composition of the biodiesel was prepared by mixing 20 wt% of biodiesel with general diesel fuel and then measuring the corrosion state of the steel sheet after 8 weeks of shaking at 5% by weight of pure water and 20 ppm of formic acid at a rate of 60 cycles / Respectively.

The corrosion resistance evaluation image for Examples and Comparative Examples is shown in Fig. 2 and evaluated according to the following criteria. Fig. 2 is an image for evaluating resistance to fuel for the surface-treated steel sheets of Examples and Comparative Examples.

◎: Corrosion area is 0% ○: Corrosion area is not more than 5%

?: Corrosion area 5 to 30% X: corrosion area 30% or more

≪ Evaluation of solution stability &

After the water-soluble organic-inorganic metal anti-corrosive coating composition is stored in a thermostat at 60 ° C. for 1 week, the viscosity rise, gelation and precipitation of the composition are observed and evaluated according to the following criteria.

?: No change such as increase in viscosity of the composition, gelation and precipitation was observed.

?: Change in the viscosity increase of 4% or more of the composition is recognized.

?: A change in viscosity increase of 10% or more of the composition is recognized.

X: Changes in the composition such as viscosity increase, gelation and precipitation are recognized.

<Evaluation of seam weldability>

Seam weldability was evaluated by using Ironman (Inverter DC Seam Welder) to maintain constant strength without spatter at 4kN pressing force, 3mpm welding speed, 33ms energization time and 10ms downtime. The evaluation criteria were evaluated by welding current range. The seam welding current range values for Examples and Comparative Examples are shown in Fig. 3 is a graph showing values of seam welding current range for the surface treated steel sheets of Examples and Comparative Examples.

?: 1.5 kA or more?: 1.0 to 1.5 kA or less?: 1.0 kA or less

&Lt; Evaluation of corrosion resistance &

The corrosion resistance was evaluated by the surface area of red rust which occurred on the surface after 480 hours of the coated steel sheet at 5% salinity concentration and spray pressure of 1 kg / cm ² at 35 ° C. The corrosion resistance evaluation image for the example and the comparative example is shown in Fig.

◎: Corrosion area is 0% ○: Corrosion area is not more than 5%

?: Corrosion area 5 to 30% X: corrosion area 30% or more

division Composition (% by weight) Solution stability Curing temperature (℃) Adhesion (mg / m ² ) Fuel resistance Corrosion resistance Processability Core weldability Silane compound Polysilicate compound Titanium compound Wax Alcohol Deteriorated gasoline Deteriorated diesel Bioethanol Biodiesel Example 1 10 3 3 One 3 ◎ 120 400 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 2 10 5 2 0.5 5 ◎ 100 600 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 3 10 7 One 0.1 7 ◎ 80 800 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 4 10 3 3 One 3 ◎ 80 400 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 5 10 5 2 0.5 5 ◎ 100 600 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 6 10 7 One 0.1 7 ◎ 120 800 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 7 10 3 3 One 3 ◎ 100 400 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 8 10 5 2 0.5 5 ◎ 80 600 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 9 10 7 One 0.1 7 ◎ 120 800 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 10 10 3 3 One 3 ◎ 100 400 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 11 10 5 2 0.5 5 ◎ 120 600 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Example 12 10 7 One 0.1 7 ◎ 80 800 ◎ ◎ ◎ ◎ ◎ ◎ ◎ Comparative Example 1 Acrylic resin 10 Silica sol 5 2 0.5 3 ◎ 100 700 △ △ △ △ △ ◎ △ Comparative Example 2 One One 5 ◎ 80 900 △ △ △ △ △ ◎ △ Comparative Example 3 3 0.1 7 ◎ 120 1100 △ △ △ △ △ ◎ △

As shown in Table 1, the compositions of Examples 1 to 12 show excellent curing reaction of the oil-and-mineral composite composition even at a curing temperature of 80 to 120 ° C, so that the fuel resistance, corrosion resistance and seam weldability Excellent results were obtained.

On the other hand, the acrylic resin contained in the compositions of Comparative Examples 1 to 3 exhibited poor results in corrosion resistance, fuel resistance, and seam weldability because the curing reaction of the polymer was not completed under the curing temperature of 80 to 120 ° C see.

Thus, Examples 1 to 12 according to the present invention are anti-corrosive coating compositions for zinc-coated steel sheets for use in automotive fuel tanks, which have low-temperature curing type solution stability and corrosion resistance.

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

Claims (12)

Which is an aqueous solution containing 5 to 30 wt% of a silane compound, 1 to 10 wt% of a polysilicate compound, 0.1 to 5 wt% of a titanium compound, 0.1 to 5 wt% of a wax and 1 to 15 wt% of an alcohol for low- Low temperature curing type anticorrosive coating composition.
The composition according to claim 1, wherein the silane compound is at least one selected from an epoxy silane compound, an amino silane compound, a hydrolyzate thereof, and a condensate of the hydrolyzate.
The method of claim 1, wherein the silane compound is a mixture of an amino-based silane compound and an epoxy-based silane compound, and the mixing ratio of the amino-based silane compound and the epoxy-based silane compound is 1: 0.2 to 10, Coating composition.
The method of claim 1, wherein the silane compound is selected from the group consisting of vinylmethoxysilane, vinyltrimethoxysilane, vinylepoxysilane, vinyltriepoxysilane, 3-aminopentyltriepoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 (Meth) acrylate, methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N- (1,3-dimethylbutylidene) -3- (triepoxysilane) (Aminoethyl) -? - aminopropyltriethoxysilane, N -? - aminopropyltrimethoxysilane, N -? - aminoethyl) -? - aminopropylmethyltriethoxysilane, N- (? -aminoethyl) -? - aminopropylmethyldimethoxysilane, N- (? -aminoethyl) Glycidoxypropyltriethoxysilane,? -Glycidoxytrimethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane,? -Metacin Methacryloxypropyltriethoxysilane,? -Mercaptopropyltrimethoxysilane,? -Mercaptopropyltriethoxysilane, and N- [2- (vinylbenzylamino) ethyl ] -3-aminopropyltrimethoxysilane. &Lt; / RTI &gt;
The composition of claim 1, wherein the polysilicate compound is at least one selected from the group consisting of lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica.
The composition according to claim 1, wherein the titanium compound is at least one selected from the group consisting of titanium carbonate, isopropylditriethanolaminotitanate, titanium lactate lactate, and titanium acetylacetonate.
The composition according to claim 1, wherein the wax is polyethylene, polytetrafluoroethylene or a mixture thereof, and is excellent in corrosion resistance.
The composition of claim 1, wherein the alcohol for low-temperature curing is at least one selected from the group consisting of ethanol, propanol and isopropanol.
Steel plate;
A zinc plated layer formed on one surface or both surfaces of the steel sheet,
And a coating layer formed on the zinc plating layer,
Wherein the coating layer is a cured product of the rust-preventive coating composition according to any one of claims 1 to 8, which is excellent in corrosion resistance.
10. The galvanized steel sheet according to claim 9, wherein the corrosion inhibiting coating composition is excellent in corrosion resistance at a curing temperature of 50 to 150 DEG C.
10. The galvanized steel sheet according to claim 9, wherein the coating layer is excellent in corrosion resistance with an adhesion amount of dry film of 0.05 to 2.0 g / m &lt; 2 &gt;.
10. The galvanized steel sheet according to claim 9, wherein the zinc plated layer is an electro-galvanized layer, a hot-dip galvanized layer, a galvannealed hot-dip galvanized layer or an aluminum alloy galvanized layer.

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