KR101808424B1 - Manufacturing method for resin coated steel sheet for car fuel tank and resin coated steel sheet for car fuel tank thereof - Google Patents

Abstract

A method for manufacturing a resin-coated steel sheet for an automotive fuel tank and a resin-coated steel sheet for an automotive fuel tank manufactured thereby are disclosed. In one embodiment, the method for manufacturing a resin-coated steel sheet for an automotive fuel tank includes: coating a resin coating solution on a surface of a base steel sheet; And the resin coating solution is dried by baking to form a resin coating layer, wherein the resin coating solution comprises 15 to 25% by weight of an epoxy resin, 15 to 25% by weight of a polyurethane resin, 0.1 to 5% by weight of a curing agent, Wherein the curing agent comprises at least one of a melamine-based curing agent and an aziridine-based curing agent, wherein the metal solution is at least one selected from the group consisting of zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ).

Description

TECHNICAL FIELD The present invention relates to a resin-coated steel sheet for automobile fuel tanks, and a resin-coated steel sheet for automobile fuel tanks produced by the method. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method for manufacturing a resin-coated steel sheet for an automotive fuel tank and a resin-coated steel sheet for an automobile fuel tank manufactured thereby. More particularly, the present invention relates to a method for manufacturing a resin-coated steel sheet for an automotive fuel tank having improved weldability, and a resin-coated steel sheet for an automotive fuel tank manufactured thereby.

A steel plate for an automobile fuel tank means a steel plate for manufacturing a tank for storing fuel such as biofuel, gasoline, and diesel for automobile driving. Such automotive fuel tank steel plates require high corrosion resistance and require durability against various fuels such as gasoline, i.e., fuel resistance. A steel plate for an automotive fuel tank is produced by forming a base layer on a base material to form a base layer, and then forming a resin layer thereon.

BACKGROUND ART [0002] The background art relating to the present invention is disclosed in Korean Patent Laid-Open Publication No. 2002-0039568 (published on May 27, 2002, entitled "Resin Coating Solution for Automobile Fuel Tank and Method for Producing Resin-Coated Steel Sheet Using the Same").

According to one embodiment of the present invention, there is provided a method for manufacturing a resin-coated steel sheet for an automotive fuel tank, which has excellent workability and weldability.

According to one embodiment of the present invention, there is provided a method for manufacturing a resin-coated steel sheet for an automotive fuel tank, which is excellent in corrosion resistance, fuel resistance and chemical resistance.

According to an embodiment of the present invention, there is provided a resin-coated steel sheet for an automotive fuel tank manufactured by the method for manufacturing a resin-coated steel sheet for an automobile fuel tank.

One aspect of the present invention relates to a method for manufacturing a resin-coated steel sheet for an automotive fuel tank. In one embodiment, the method for manufacturing a resin-coated steel sheet for an automotive fuel tank includes: coating a resin coating solution on a surface of a base steel sheet; And the resin coating solution is dried by baking to form a resin coating layer, wherein the resin coating solution comprises 15 to 25% by weight of an epoxy resin, 15 to 25% by weight of a polyurethane resin, 0.1 to 5% by weight of a curing agent, Wherein the curing agent comprises at least one of a melamine-based curing agent and an aziridine-based curing agent, wherein the metal solution is at least one selected from the group consisting of zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ).

In one embodiment, the metal solution may include at least one metal sulfide compound selected from zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ) in a weight ratio of 1: 0.1 to 1: 1.5.

In one embodiment, the pH of the resin coating solution may be 9 to 11.

In one embodiment, the baking may be carried out at 180 ° C to 230 ° C.

In one embodiment, the resin coating solution may be applied to the steel sheet so that the steel sheet single-sided reference deposit amount is 0.9 to 2 g / m ² after baking.

Another aspect of the present invention relates to a resin-coated steel sheet for an automotive fuel tank manufactured by the method for manufacturing a resin-coated steel sheet for an automobile fuel tank. In one embodiment, the resin-coated steel sheet for an automotive fuel tank comprises a base steel plate; And 15 to 25 wt% of an epoxy resin, 15 to 25 wt% of a polyurethane resin, 0.1 to 5 wt% of a curing agent, 10 to 35 wt% of a metal solution, and a resin coating layer formed on the surface of the base steel sheet. Wherein the curing agent comprises at least one of a melamine-based curing agent and an aziridine-based curing agent, and the metal solution is at least one selected from the group consisting of zinc sulfate (ZnSO ₄ ) And nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ).

In one embodiment, the metal solution may include at least one metal sulfide compound selected from zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ) in a weight ratio of 1: 0.1 to 1: 1.5.

In one embodiment, the resin coating layer may have a thickness of 0.5 to 3 탆.

The resin-coated steel sheet for an automobile fuel tank manufactured by the method for producing a resin-coated steel sheet for an automobile fuel tank according to the present invention is excellent in workability and welding characteristics, and excellent in corrosion resistance, fuel resistance and chemical resistance.

1 shows a method of manufacturing a resin-coated steel sheet for an automotive fuel tank according to one embodiment of the present invention.
2 shows a resin-coated steel sheet for an automotive fuel tank according to one embodiment of the present invention.
Fig. 3 shows changes in nugget size according to the number of consecutive RBs when the specimen according to the present invention is spot-welded.

Hereinafter, the present invention will be described in detail. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to be exemplary, self-explanatory, allowing for equivalent explanations of the present invention.

car For fuel tank  Method for manufacturing resin-coated steel sheet

One aspect of the present invention relates to a method for manufacturing a resin-coated steel sheet for an automotive fuel tank. 1 shows a method of manufacturing a resin-coated steel sheet for an automotive fuel tank according to one embodiment of the present invention. Referring to FIG. 1, the method for manufacturing a resin-coated steel sheet for an automotive fuel tank includes the steps of: (S10) applying a resin coating liquid; And (S20) a drying step. More specifically, the method for manufacturing a resin-coated steel sheet for an automobile fuel tank comprises the steps of: (S10) applying a resin coating solution to a surface of a base steel sheet; And (S20) baking the resin coating solution to form a resin coating layer.

Hereinafter, a method for manufacturing a resin-coated steel sheet for an automotive fuel tank according to the present invention will be described in detail.

(S10) Resin coating liquid application step

This step is a step of applying a resin coating liquid to the surface of the base steel sheet. In one embodiment, the base steel sheet may be formed with a plating layer including at least one of zinc, a zinc alloy, a nickel, and a nickel alloy. A plating layer containing at least one of zinc (Zn), nickel (Ni), zinc-nickel (Zn-Ni) and zinc-nickel-silicon (Zn-Ni-Si) may be formed. In one embodiment, the plating layer can be formed by a hot dip coating method, an electroplating method, or the like. For example, the coating layer adhesion amount may be 20 to 40 g / m ² . The base steel sheet may have excellent durability and corrosion resistance when formed with the above amount of adhesion.

Resin coating solution

In one embodiment, the resin coating liquid is formed to form a resin coating layer to secure the corrosion resistance of the base steel sheet and to ensure durability against biofuel, gasoline, diesel, etc., that is, to secure fuel resistance. The resin coating liquid includes an epoxy resin, a polyurethane resin, a curing agent, and a metal solution.

Epoxy resin

The epoxy-based resin is included for the purpose of enhancing the adhesion of the resin coating liquid component to the steel sheet, as a binder for fixing the components of the resin coating solution, and for improving corrosion resistance and fuel resistance.

In one embodiment, the weight average molecular weight (Mw) of the epoxy resin may be 25,000 to 50,000 g / mol. When the epoxy resin having a weight-average molecular weight in the above range is applied, the resin coating layer of the present invention is excellent in the adhesion to the steel sheet and excellent in durability, fuel resistance, corrosion resistance and mechanical strength.

In one embodiment, the epoxy resin is contained in an amount of 15 to 25% by weight based on the total weight of the resin coating liquid. When the epoxy resin is contained in an amount of less than 15% by weight, the adhesion of the resin coating layer is deteriorated. When the epoxy resin is contained in an amount exceeding 25% by weight, the fuel resistance may be deteriorated.

Polyurethane resin

The polyurethane resin is included for the purpose of enhancing the adhesion of the resin coating liquid component to the steel sheet, acting as a binder for fixing the constituents of the resin coating liquid, and improving the corrosion resistance and fuel resistance.

In one embodiment, the polyurethane resin is contained in an amount of 15 to 25% by weight based on the total weight of the resin coating liquid. When the polyurethane resin is contained in an amount of less than 15% by weight, the adhesion of the resin coating layer is lowered, and if it exceeds 25% by weight, the fuel resistance may be deteriorated.

In one embodiment, the epoxy resin and the polyurethane resin may be contained in a weight ratio of 1: 0.5 to 1: 1.5. When included in the above weight ratio, the mechanical strength of the resin coating layer of the present invention, the adhesion with the base steel sheet, and the fuel resistance can be excellent at the same time.

Hardener

The curing agent is included for the purpose of accelerating the curing of the epoxy resin and the polyurethane system during the resin curing of the resin coating liquid. The curing agent includes at least one of a melamine-based curing agent and an aziridine-based curing agent. When the above-mentioned curing agent is included, curing of the epoxy resin and the polyurethane system can be easily performed.

In one embodiment, the curing agent is included in an amount of 0.1 to 5% by weight based on the total weight of the resin coating liquid. If the amount of the curing agent is less than 0.1% by weight, the resin component may melt or discolor and the curing may not be performed properly. On the other hand, when the addition amount of the curing agent exceeds 5% by weight, the curing effect may be lowered or the mechanical strength of the resin coating layer may be lowered. For example, 0.5 to 2% by weight.

In one embodiment, the curing agent may include a melamine-based curing agent and an aziridine-based curing agent in a weight ratio of 1: 0.5 to 1: 1.5. The curing efficiency and the mechanical strength of the resin coating layer may be excellent in the weight ratio.

Metal solution

The metal solution is included for the purpose of improving the weldability of the resin coating layer and improving the weldability.

In one embodiment, the metal solution comprises at least one of a zinc sulphide (ZnSO ₄ ) and a nickel sulphate (NiSO ₄ ) metal compound and ammonia (NH ₃ ).

In one embodiment, the metal solution is prepared by dissolving the metal sulfide compound in water to form a first mixed solution; Adding ammonia to the first mixed solution to sludge excess metal salt not dissolved in water; And removing the sludge.

In one embodiment, the metal solution may include the metal sulfide compound and ammonia (NH ₃ ) in a weight ratio of 1: 0.1 to 1: 1.5. When included in the above range, a stable metal complex can be formed. As another example, the metal solution may contain a metal sulfide compound, ammonia, and water in a weight ratio of 1: 0.1 to 1.5: 0.1 to 10.

In one embodiment, the metal solution is contained in an amount of 10 to 35% by weight based on the total weight of the resin coating liquid. When the metal solution is contained in an amount of less than 10% by weight, it is difficult to ensure conductivity and weldability at the time of forming the resin coating layer. If the content of the metal solution exceeds 35% by weight, the corrosion resistance, solution stability and mechanical strength of the resin coating layer may be deteriorated. For example, 10 to 20% by weight.

In one embodiment, the resin coating liquid may have a solids content of 10 to 35% by weight. When it is included in the above range, the workability can be excellent. For example, 15 to 20% by weight.

In one embodiment, the pH of the resin coating solution may be 9 to 11. In the above range, workability and corrosion resistance, solution stability and mechanical strength of the resin coating layer can be excellent.

solvent

The solvent may be included for the purpose of ensuring the mixing and workability of the resin coating solution, improving the wettability of the steel sheet, and rapidly performing the drying speed after coating the steel sheet in forming the resin coating layer.

The solvent may include at least one of water, methanol, ethanol, 2-propanol, 2-methoxypropanol and 2-butoxyethanol. When the above-mentioned solvent is used, the resin coating liquid can have excellent mixing properties and workability.

additive

In one embodiment, the resin coating liquid may further include an additive. For example, a wetting agent. The wetting agent serves to improve the leveling property of the coating. In one embodiment, the wetting agent may comprise a fluorochemical wax.

In one embodiment, the additive may be included in an amount of 0.01 to 10% by weight based on the total weight of the resin coating liquid. When added in the above range, the leveling property can be improved without impairing the physical properties of the resin coating layer.

(S20) Drying step

In this step, the resin coating liquid is baked to form a resin coating layer. In one embodiment, the baking may be carried out at 180 ° C to 230 ° C. The resin coating layer can be easily formed at the drying temperature.

In one embodiment, the resin coating solution may be applied to the steel sheet so that the steel sheet single-sided reference deposit amount is 0.9 to 2 g / m ² after baking. When applied in the above range, the resin coating layer may have excellent corrosion resistance, solution stability and mechanical strength.

In one embodiment, the resin coating solution may be applied through a coater facility to form a coating layer. In one embodiment, the solution in the drip pan is applied to a steel sheet in an applicator roll by being buried in a pick-up roll, and then dried in an oven to form a rust preventive coating. The adhesion amount of the resin coating liquid can be adjusted by the driving direction of the roll, the rotation speed, the pressure of each roll, and the like.

In one embodiment, the resin coating solution may be applied after baking to a thickness of 0.5 to 3 탆. When applied in the above range, the resin coating layer may have excellent corrosion resistance, solution stability and mechanical strength. For example, to a thickness of 1 to 2 mu m.

car For fuel tank  Automobiles manufactured by resin-coated steel sheet manufacturing method For fuel tank  Resin coated steel plate

Another aspect of the present invention relates to a resin-coated steel sheet for an automotive fuel tank manufactured by a method for manufacturing a resin-coated steel sheet for an automobile fuel tank. In one embodiment, the resin-coated steel sheet for an automotive fuel tank comprises a base steel plate; And a resin coating layer formed on the surface of the base steel sheet, wherein the resin coating layer comprises 15 to 25 wt% of an epoxy resin, 15 to 25 wt% of a polyurethane resin, 0.1 to 5 wt% of a curing agent, 10 to 35 wt% And a residual amount of a solvent is baked and dried. The components and content of the resin coating liquid are the same as those described above, and therefore, a detailed description thereof will be omitted.

2 shows a resin-coated steel sheet for an automotive fuel tank according to one embodiment of the present invention. 2, the plating layer 130 may include at least one of zinc, zinc alloy, nickel, and nickel alloy on the surface of the base steel sheet 110 in one embodiment. A plating layer containing at least one of zinc (Zn), nickel (Ni), zinc-nickel (Zn-Ni) and zinc-nickel-silicon (Zn-Ni-Si) may be formed. In one embodiment, the resin-coated steel sheet 100 comprises a base steel sheet 110; A plating layer 130 formed on the surface of the base steel sheet 110; And a resin coating layer 150 formed on the surface of the plating layer 130.

Wherein the curing agent comprises at least one of a melamine-based curing agent and an aziridine-based curing agent, and the metal solution is at least one of zinc sulfide (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) NH ₃ ).

The metal solution may include at least one metal sulfide compound selected from zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ) in a weight ratio of 1: 0.1 to 1: 1.5.

In one embodiment, the resin coating layer may have a thickness of 0.5 to 3 탆. The resin coating layer may have excellent corrosion resistance, solution stability and mechanical strength when formed into the above thickness.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Example  And Comparative Example

The components used in the following Examples 1 to 6 and Comparative Examples 1 to 4 are as follows.

(A) Epoxy resin: An epoxy resin having a weight average molecular weight (Mw) of 25,000 to 50,000 g / mol was used.

(B) Polyurethane resin: Esacote PU79 (lamberti, Italy) was used.

(C) Hardener: (C1) A melamine-based curing agent was used. (C2) aziridine curing agent was used.

(D) Metal solution: (D1) Nickel sulfate (NiSO ₄ ) is dissolved in water with a metal sulfide compound, and then ammonia (NH ₃ ) Solution. (D2) A metal solution was prepared by dissolving zinc sulfate (ZnSO ₄ ) as a metal sulfide compound in water and adding ammonia (NH ₃ ) (zinc sulfate: ammonia: water at a weight ratio of 1: 1: 5).

(E) Solvent: pure water was used.

A resin coating liquid containing the components and contents as shown in Table 1 below was prepared for Examples 1 to 6 and Comparative Examples 1 to 4.

A base steel sheet (cold-rolled steel sheet) on which a Zn-Ni (10 at.% Ni) plating layer was formed was prepared. The Zn-Ni plating layer was formed by an electroplating method, and the plating amount was 30 g / m ² on one side basis.

On the surface of the plating layer and the Examples 1 to 6 and Comparative Examples 1-4 by coating each of the prepared resin and baking the coating liquid was dried at 200 ℃, wherein the steel sheet based on a single side coating weight 1g / m ² in accordance with a thickness of 1.5㎛ A resin coating layer was formed to prepare a resin-coated steel sheet specimen.

Property evaluation

The properties of the resin-coated steel sheets of Examples 1 to 6 and Comparative Examples 1 to 4 were evaluated in the following manner. The results are shown in Table 3 below.

(1) Evaluation of solution stability (aging property): The degree of gelation of the resin coating solution was evaluated. It was judged whether or not gelation was observed through visual observation. When the resin coating liquids of Examples 1 to 6 and Comparative Examples 1 to 4 were elapsed after 15 days, it was judged that the sludge or solution did not gel and the gel was judged to be defective.

(2) Evaluation of Corrosion Resistance: After 1,000 hours passed after the salt spray test, the rust development was judged for Examples 1 to 6 and Comparative Examples 1 to 4, and it was judged to be defective when white rust was generated.

(3) Evaluation of adhesion: A 7 mm dome was made through the Ericsson test for Examples 1 to 6 and Comparative Examples 1 to 4, and the peeled specimen was peeled off from the top of the dome. Respectively.

(4) Evaluation of Weldability: The above Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to continuous ROT welding 1000 points at a welding current of 9.5 kA and a pressing force of 350 kgf / cm 2 under the conditions shown in Table 2 below. Good when the size was 3.5 mm or more, and poor when the size was less than 3.5 mm.

(* 1 cycle = 1/60 sec)

The results are shown in Table 3. Referring to Table 3, Examples 1 to 6 of the present invention were excellent in solution stability, corrosion resistance, adhesion, and weldability. In Comparative Examples 1 to 4, It was found that the solution stability, the corrosion resistance, the adhesion or the weldability were deteriorated as compared with those of Examples 1 to 6.

3 is a graph showing changes in nugget size according to the number of consecutive RBs when the specimen of Example 1 according to the present invention is spot-welded. Referring to FIG. 3, it was found that the specimen of Example 1 was excellent in weldability even at 800 RB points or more.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: Resin-coated steel plate 110: Base steel plate
130: Plating layer 150: Resin coating layer

Claims (8)

Applying a resin coating liquid to the surface of the base steel sheet; And baking the resin coating solution to form a resin coating layer,
Wherein the resin coating liquid contains 15 to 25% by weight of an epoxy resin having a weight average molecular weight of 25000 to 50,000 g / mol, 15 to 25% by weight of a polyurethane resin, 0.1 to 5% by weight of a curing agent, 10 to 35% Lt; / RTI >
The epoxy resin and the polyurethane resin are contained in a weight ratio of 1: 1 to 1: 1.5,
The curing agent includes at least one of a melamine-based curing agent and an aziridine-based curing agent,
Wherein the metal solution comprises at least one metal sulfide compound selected from zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ) in a weight ratio of 1: 1 to 1: A method for manufacturing a coated steel sheet.
delete The method according to claim 1,
Wherein the resin coating solution has a pH of from 9 to 11.
The method according to claim 1,
Wherein the baking is performed at a temperature of 180 ° C to 230 ° C.
The method according to claim 1,
Wherein the resin coating solution is applied to the steel sheet so that the steel sheet is one side of the steel sheet with a reference deposition amount of 0.9 to 2 g / m ² after baking.
Base steel plate; And
And a resin coating layer formed on the surface of the base steel sheet,
Wherein the coating layer contains 15 to 25% by weight of an epoxy resin having a weight average molecular weight of 25000 to 50000 g / mol, 15 to 25% by weight of a polyurethane resin, 0.1 to 5% by weight of a curing agent, 10 to 35% Is formed by baking the resin coating liquid,
The epoxy resin and the polyurethane resin are contained in a weight ratio of 1: 1 to 1: 1.5,
Wherein the curing agent comprises at least one of a melamine-based curing agent and an aziridine-based curing agent,
Wherein the metal solution comprises at least one metal sulfide compound selected from zinc sulfate (ZnSO ₄ ) and nickel sulfate (NiSO ₄ ) and ammonia (NH ₃ ) in a weight ratio of 1: 1 to 1: Coated steel plate.
delete The method according to claim 6,
Wherein the resin coating layer has a thickness of 0.5 to 3 占 퐉.

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