JPH1067235A - Fuel container for automobile excellent in corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the use of Pb and obtain excellent corrosion resistance in environment of fuel such as gasoline by using a hot-dipped aluminum-coated steel sheet having a resin film on an outermost surface of an inner face or/and an outer face as a constituent member of a fuel container. SOLUTION: A fuel container constituted by molding an upper container and a lower container into a bowl type having a flange 2 by press-molding and seam-welding a flange part by putting these containers up and down together is provided with a fuel supply port 3, a fuel supply pump, a fuel hose 4, and a separator 5 which prevents sound of fuel 6 caused by waving. In this case, a hot-dipped aluminum-coated steel sheet having a resin film on an outermost surface of an inner face or/and an outer face is used as a constituent member of the fuel container. Or, a hot-dipped aluminum-coated steel sheet having a resin chromate film on a surface of an inner face or/and an outer is face used as a constituent member, and the thickness of the resin film or the resin chromate film is set to a scope of 0.1 to 2μm. Consequently, it is possible to eliminate Pb pollution in environment and obtain the fuel container excellent in corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Since the present invention does not substantially contain Pb, there is little concern about environmental pollution when a car is discarded, and a highly corrosive fuel such as deteriorated gasoline or gasoline containing alcohol is used. Provided is an automobile fuel container which is resistant to corrosion when sealed and has excellent corrosion resistance.

[0002]

2. Description of the Prior Art Fuel containers (fuel tanks) for motor vehicles are often designed last, usually in accordance with the design of the vehicle body, so that their shape is generally very complex. As shown in FIG. 1, the fuel supply port 3, a fuel supply pump (not shown), a fuel hose 4, a fuel hose 4 for returning excess fuel 6, and a separator 5 (partition plate) for preventing the noise of the fuel from swaying. Etc. The fuel container main body 1 is formed by integrating a pair of bowl-shaped molded bodies by seam welding the flange portions 2. Each component is joined by spot welding, soldering or brazing.

[0003] This fuel container is an important security part of automobiles.
The properties to be provided include sufficient corrosion resistance to the fuel, no leakage or permeation of the fuel, no fatigue after molding, and no cracking due to impact.
Regarding corrosion resistance, of course, there is no concern about perforation due to corrosion, but there is no generation of a large amount of corrosion products that could lead to clogging of the filter at the inlet of the fuel pump inside the fuel container. It is also important.

[0004] In order to obtain fuel containers having these various characteristics, various contrivances have been made in terms of materials, production, production methods and the like. As a result of ingenuity from the material side, fuel containers made of Pb-Sn plated steel sheets that have sufficient corrosion resistance to fuel, generate little corrosion products, are easy to weld and solder, and have excellent production efficiency Commonly used.
However, on the other hand, as is well known, Pb is a metal that exerts a load on the environment. As described above, the Pb-Sn plated steel sheet can be easily soldered and brazed, but the component of the solder is Sn-Pb-based and also contains Pb. Therefore, recently, a fuel container that does not use Pb at all has been desired.
As a candidate, a fuel container made of an aluminum (Al-Si) plated steel sheet has been studied.

Since a stable oxide film is formed on the surface of aluminum, it has good corrosion resistance to organic acids generated when gasoline, alcohol, gasoline and the like are deteriorated. However, there are some problems in putting a fuel container made of an aluminum-plated steel plate into practical use, and its use has been limited until now. The main reason was corrosion resistance after molding into a fuel container. Aluminized steel sheet is a very hard Fe-Al formed at the interface between the coating layer and the steel sheet.
Since it has an intermetallic compound layer of -Si (hereinafter, referred to as an alloy layer), plating exfoliation and plating cracks easily occur from this portion as a starting point. Furthermore, even if minute cracks occur, aluminum plating does not have a sacrificial anticorrosion effect on the base iron, not to mention the peeling of the plating, so that corrosion proceeds in the thickness direction of the plate, and there is a concern that perforation may occur in a short period of time. was there. In addition, soldering and brazing to an aluminum-plated steel sheet are generally difficult, and there is a concern that there is no method for joining small parts to this steel sheet with high productivity without lowering the performance of the fuel container made of the aluminum-plated steel sheet. .

[0006]

The present invention solves the above-mentioned problems by providing a new fuel which is environmentally friendly because Pb is not used and which has excellent corrosion resistance in the environment of fuels such as gasoline. A container is provided.

[0007]

Means for Solving the Problems The present inventors have satisfied various characteristics as a fuel container as described above,
Various studies were conducted in order to develop a fuel container that does not use a fuel cell. As a result, by using a material in which the surface of an aluminum-plated steel sheet is coated with a resin film, a fuel container which does not use Pb and has no fear of short-term perforation has been invented. That is, when processing a steel sheet, it is found that cracks occur in the aluminum plating layer due to poor lubricity of the aluminum plating surface, and a resin film having good lubricity is applied to the aluminum plating surface to prevent this. This greatly improved the corrosion resistance after processing.

The gist of the present invention is a fuel container in which flange portions of a pair of bowl-shaped molded bodies having flanges are continuously seam-welded to form a unitary fuel container, the constituent members of which are inner surfaces and / or An automotive fuel container with excellent corrosion resistance, characterized by being a hot-dip aluminized steel sheet having a resin film on the outermost surface. Alternatively, there is provided a fuel container in which flange portions of a pair of bowl-shaped molded bodies having flanges are continuously seam-welded to form an integral fuel container, the constituent member of which has a resin chromate film on an inner surface and / or an outer surface. An automotive fuel container with excellent corrosion resistance characterized by being an aluminized steel sheet. Alternatively, the above-mentioned automobile fuel container having excellent corrosion resistance is characterized in that a resin film or a resin chromate film has a thickness of 0.1 to 2 μm.

Hereinafter, the present invention will be described in detail. The fuel container according to the present invention has a form in which an upper container and a lower container are formed into a bowl shape having a flange by press molding or the like, and the upper and lower portions are seam-welded to the flange portion. Although the structure is not particularly limited, it is desirable to provide a fuel filler port, a fuel supply pump, a fuel hose, a fuel hose for returning excess fuel, a separator for preventing the noise of the fuel from swaying, and the like as in a normal fuel container. The method of joining them is spot welding, soldering or brazing. Although the difference between soldering and brazing is somewhat unclear, here, joining with a metal having a melting point of 450 ° C. or more is referred to as brazing, and joining with a metal at a temperature lower than that is referred to as soldering. The most important feature of the present invention is that the material constituting the fuel container, that is, the container main body, as well as the material of the internal separator, fuel filler, and the like do not substantially contain Pb. The fuel container body containing Pb is an aluminum-plated steel sheet having a resin film on the outermost layer. In addition, the solder and the brazing material are also aluminum-based materials that do not substantially contain Pb.

In the conventional bare aluminum-plated steel sheet, there was a concern that the corrosion resistance would be greatly degraded due to the working, but in the present invention, this was solved by the outermost resin film. This is because bare aluminum-plated steel sheet does not have good lubrication even if it is coated with oil, causing cracks in plating and leading to significant deterioration of corrosion resistance, but providing a resin film with excellent lubricity on the surface This is because the plating crack was suppressed. If the film thickness is too small, the film cannot cover the entire surface, and the effect of improving corrosion resistance after processing is small.
The larger the film thickness is, the more advantageous it is for the corrosion resistance after processing. However, if it is too large, welding, soldering and brazing become difficult and the production efficiency as a fuel container is hindered.

In the present invention, the film thickness is 0.1 to 2 μm after molding.
m is desirable. More preferably, 0.3 to 1 μm
m. This resin film may be on both sides,
The effect is obtained even if only the outer surface or only the inner surface is used. The effect can be easily expected if there is a film on the inner surface, but the reason why the effect is effective only on the outer surface is considered as follows. Press working is usually used for molding the fuel container, and surface lubrication greatly contributes to press workability. Particularly, since the contribution of lubricity on the outer surface side is large, even if the film is applied only on the outer surface side, it seems that the inner surface is also effective in terms of plating damage.

In the present invention, the material for brazing and soldering is preferably aluminum. It is generally said that soldering and brazing to the aluminum surface is difficult due to a stable passive film on the aluminum surface, but by using an appropriate flux, bonding with good productivity is possible. Aluminum-based brazing has a higher melting point than conventional Pb-Sn-based solder, so that good brazing is possible even with a resin film. Other Ni-based materials are also possible.

In the present invention, the fuel container has a resin film on its surface, but there is no particular limitation on the composition and structure of the resin film. As a system used as a resin,
For example, there are ethylenically unsaturated compounds such as acrylic acid and / or methacrylic acid ester, vinyl carboxylate, vinyl ether, styrene, acrylamide, acrylonitrile, and vinyl halide, and epoxy, urethane, and polyester. However, the resin film used in the present invention is particularly preferably a resin chromate film. The resin chromate is obtained by mixing chromic acid, a resin, and the like in a chromate treatment liquid, and forming a film thereof, in which the chromic acid compound is uniformly dispersed in the film. C in this
r ⁶⁺ elutes during use as a tank, and stable corrosion resistance is obtained.

[0014] Compared with the resin coating treatment after the chromate treatment which is a standard resin film treatment, the treatment can be performed in one step, so that the treatment is advantageous in cost. Further, by using a resin that can be cured at a low temperature, there is an advantage that a special drying furnace is not required and the resin can be processed by a conventional chromate processing equipment. When a conventional chromate facility is used, it is desirable to use an emulsion-type resin or the like that can be baked at a low temperature. Further effects can be expected to be further improved by adding, for example, a small amount of a lubricant, a rust preventive pigment or the like to the resin.

Other features from the material side will be further described. The aluminum-plated steel sheet, which is the material of the molded body, has an alloy layer and an aluminum plating layer, and the aluminum plating layer contains about 10% of Si. This is added to suppress the growth of the alloy layer. As described above, the alloy layer formed by the hot-dip aluminum plating is very hard and brittle, and thus easily becomes a starting point of destruction, and impairs the formability of the steel sheet itself.
Even with an ordinary alloy layer of about 2 to 3 μm, the ductility of the steel sheet is reduced by about 3 points. If the amount of Si is small, the effect of reducing the alloy layer is small, and if it is too large, the effect is saturated. Therefore, the amount of Si is 4 ~
About 13% is preferable.

In general, the corrosion resistance of a flat plate tends to increase as the amount of aluminum plating attached increases, but this tendency is not necessarily maintained after severe molding. Conversely, the adhesion amount is desirably 50 g / m ² or less in order to impair the weldability and deteriorate the productivity as a fuel container. The lower limit of the amount that can be industrially produced is about 20 g / m ² .
It is preferable that the thickness of the alloy layer be thin as described above. In the present invention, the surface of the plating has a resin film.
In the resin film, chromate, silica,
It is possible to add phosphoric acid or the like.

The steel component of the fuel container is not particularly limited. However, it is desirable to apply IF steel excellent in workability only to the part to be subjected to complicated forming, and it is also desirable to use a steel sheet to which several ppm of B is added in order to secure the welding airtightness after welding, secondary workability, and the like. . The method for producing the aluminum-plated steel sheet for the fuel container is a usual method. The steel component is adjusted and melted by, for example, a converter-vacuum degassing process, and the steel slab is manufactured by a continuous casting method or the like and hot rolled. Further, after cold rolling, hot-dip aluminum plating is performed, for example, using a hot-dip plating line of a Zenzimer method. The recrystallization annealing is performed in this hot-dip plating line, and after adjusting the amount of aluminum plating to be applied, a resin film is applied on the rear surface of the aluminum plating or on the coating line.

[0018]

Next, the present invention will be described in more detail by way of examples. Actual fuel containers have various shapes and are not uniform. Therefore, hot-dip aluminized steel sheet (0.8 mm thick) having various steel components, plating compositions, and resin films and Pb
Using a Sn alloy plated steel sheet as a material, several types of fuel containers having different processes were manufactured. The Pb content as an impurity in the aluminum plating layer of the hot-dip aluminized steel sheet is 0.0
01% or less. In order to grasp the processing degree quantitatively,
The evaluation was based on the thickness reduction rate. In this method, the sheet thickness is measured at each part before and after molding, the sheet thickness reduction rate is calculated, and the workability is evaluated using the maximum value. Spot welding and brazing were used to join the small parts after molding. Table 1 shows the steel composition of the materials used, and Table 2 shows the specifications of the resin film.
Table 3 shows the manufacturing conditions of the fuel container. The corrosion resistance of the fuel container thus manufactured was evaluated by the method shown below,
Table 3 also summarizes the results. Some of the used materials were coated with resin. As the resin film, both the resin coating after the chromate treatment and the resin chromate treatment were used. The Al-Si system was used for brazing.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

(1) Evaluation of corrosion resistance The corrosion resistance to gasoline was evaluated. In the method, the molded fuel container was kept at a constant temperature, and the test liquid was continuously circulated.
After the test, the fuel container was cut out and visually inspected for the corrosion state of the fuel container. [Test conditions] Test solution: Gasoline + distilled water 10% + formic acid 200 ppm Test period: Left at 40 ° C for 3 months [Evaluation criteria] 〇: Less than 0.1% of red rust △: 0.1 to 5% of red rust or white There is rust generation ×: Red rust generation exceeds 5% or white rust is remarkable (2) Pb elution property After the test of (1), the amount of Pb eluted in the test solution was quantified by a wet method to evaluate Pb elution property. [Evaluation criteria] 〇: No elution (below detection limit) ×: Elution

As shown in Table 3, a fuel container manufactured by aluminum plating without a resin film is coated with a thick chromate and shows moderate corrosion resistance in a low processing shape.
15% reduction in thickness as seen in many actual fuel containers
Corrosion resistance deteriorates with the above-mentioned high processing shape (Comparative Example 1).
A fuel container using a conventionally used Pb-Sn-plated steel sheet (Comparative Example 2) and an aluminum-plated steel sheet also require Pb-S
In the case of using n-type solder (Comparative Example 4), the corrosion resistance is good, but there is a concern that Pb is eluted. A fuel container made of a material obtained by applying a chromate to Zn-Ni has extremely poor corrosion resistance. By molding from a material in which a resin film is applied to aluminum plating and using an Al-based brazing material, a fuel container having excellent corrosion resistance after processing can be obtained without concern about elution of Pb. However, in Example 16, it is necessary to slightly change the pressing force and the current value at the time of welding, and the productivity at the time of welding is somewhat difficult.

[0024]

The present invention solves the concern of Pb contamination to the environment, which has recently become a problem, and provides a fuel container having excellent corrosion resistance even when molded into a severe shape.
It also responds to the growing voice of environmental conservation and has a significant industrial contribution.

[Brief description of the drawings]

FIG. 1 is a view showing a schematic structure of an automobile fuel container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel container main body 2 Flange 3 Fuel filler 4 Fuel hose 5 Separator 6 Fuel

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyoshi Okada 1-1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Yawata Works

Claims (3)

[Claims] 1. A fuel container in which flange portions of a pair of bowl-shaped moldings each having a flange are continuously seam-welded to form an integral fuel container, the constituent member of which is a resin film on the innermost surface and / or outermost surface. An automotive fuel container having excellent corrosion resistance, characterized in that it is a hot-dip aluminized steel sheet having: 2. A fuel container in which flange portions of a pair of bowl-shaped molded bodies each having a flange are continuously seam-welded to form an integral fuel container, the constituent member of which is a resin chromate film on an inner surface and / or an outer surface. An automotive fuel container having excellent corrosion resistance, characterized in that it is a hot-dip aluminized steel sheet having: 3. The automobile fuel container having excellent corrosion resistance according to claim 1, wherein the thickness of the resin film or the resin chromate film is 0.1 to 2 μm.