JPS6164442A - Steel plate for weldable high corrosion-resistant fuel vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention 8A is a highly corrosion-resistant fuel with excellent weldability that can be used as a steel plate for fuel containers, a container material for storing fuels such as gasoline, alcohol fuel, and alcohol-containing gasoline. This invention relates to steel plates for containers.

(Prior art) With the recent sudden death of the oil situation (rise in oil costs and decrease in production), alcohol fuels such as methyl alcohol and ethyl alcohol or methyl Fuel mixed with alcohol such as alcohol, ethyl alcohol, methyl tert-butyl alcohol (MTBA), etc.
The use of so-called gasohol as a total alternative fuel has been proposed and is being put into practice.

Vi JP-A-1983-1977 is applied to automobile fuel container materials for these alcohol fuels or alcohol-added gasoline (gasohol).
Pb--Sn alloy coated steel sheets have been used, which have been published in many patent publications such as JP-A-23345 and JP-A-51-115240, but there has been a problem in that the corrosion resistance of the steel sheets is significantly deteriorated. The cause is Pb-S
Since the coating layer of the n-alloy steel sheet is composed of a eutectic alloy of Pb and Sn mainly composed of Pbt, for example: (1) Pb metal is severely corroded by methyl alcohol, so the Pb metal layer of the coating layer parts are susceptible to corrosion.

(2) P is produced by acetaldehyde, acetic acid (the main oxidation product of ethyl alcohol), formaldehyde, or formic acid (the main oxidation product of methyl alcohol), which are mainly formed when alcohol fuel or alcohol-added gasoline is oxidized.
The b metal is severely corroded, and the Pb metal layer in the coating layer is likely to be corroded.

(3) Moisture contained in alcohol or main oxidized components of alcohol increase corrosion from pinholes formed in the coating layer.

Due to these reasons, the corrosion resistance of Pb-Sn alloy plated steel sheets is significantly deteriorated.

For this reason, container steel sheets for storing such fuels have fewer pinholes in the coating layer and are free from alcohol and alcohol oxidation main components (formaldehyde).

A highly corrosion-resistant material with excellent corrosion resistance against acetaldehyde, formic acid, and succinic acid is required. or,
In recent years, there has been a demand for materials with even better corrosion resistance for the outer surface of containers due to the problem of corrosion caused by snow melting salts.

(Problems to be solved by the invention) The present invention has been made in response to these situations,
The object of the present invention is to solve problems regarding the corrosion resistance of Pb-Sn alloy plated steel sheets to alcohol fuels or alcohol-containing fuels, and to provide a steel sheet for fuel containers that has excellent weldability.

Furthermore, the present invention provides Pb for snow melting salt on the outer surface of the fuel container.
The object of the present invention is to provide a steel plate for a fuel container that has further improved corrosion resistance than a Sn alloy plated steel plate.

(Means for solving the problem) The gist of the present invention is that the main component of Pbl is 3μ
Aluminum or stainless steel on one or both sides of a steel plate plated with a Pb-Sn alloy containing % or more of Sn.

Coated with a corrosion-resistant paint containing one or more of nickel, cobalt, tin, chromium, and graphite powders or their alloy powders in an amount of 30% or more by weight based on the total nonvolatile content, or a Pb-Sn composite. One side of the gold-plated steel plate is coated with the above corrosion-resistant paint, and the other side is coated with Zn or F! , Zn-based alloy plating layer or Zn powder and Zn
By mixing one or two types of alloy powders with each powder of aluminum, nickel, cobalt, tin, chromium, iron, or one or more types of alloy powders, it is possible to form a mixture of 60% by weight based on the non-volatile content of the paint. This is a weldable, highly corrosion-resistant fuel container steel plate completely coated with one of the above-mentioned corrosion-resistant paints.

The present invention will be explained in detail below.

In the present invention, p, Pb--Sn alloy plating is first applied to the surface of a steel plate by a welding plating method or an electroplating method. This Pb-Sn alloy plated steel sheet may be directly plated with Pb-Sn alloy after the surface of the steel sheet is cleaned and activated, or may be plated with Ni, Co*C on the surface of the steel sheet.
The material may be coated with another metal or alloy such as U, and then coated with KPb-8n alloy.

The thickness of the Pb-Sn alloy plating layer in this case is 1 to 1
0μ (preferably 2.5 to 7.5μ) is good.

If the thickness of the Pb-Sn alloy coating layer is less than 1μ, Pb-
As the 8N metal layer becomes extremely thin, many pinholes occur, which tends to deteriorate corrosion resistance. On the other hand, Pb-Sn
If the thickness of the alloy plating layer exceeds 10 μm, its workability deteriorates and it is not preferred from an economic standpoint. Also, this P
The b-Sn alloy plating layer is not particularly specified, but in order to form a plating layer with few pinholes, the Sn alloy plating layer is
Preferably, a Pb-Sn alloy coating layer with a content of 3 to 25% is used.

Next, on one or both sides of the Pb-Sn alloy plating layer formed on the surface of these steel plates, one or more kinds of T-paints of aluminum, stainless steel, nickel, cobalt, tin, chromium, graphite powders or their alloy powders are applied. Roll coater with corrosion-resistant paint containing 30% by weight or more based on non-volatile content.

Curtain 70 - Coat using a coater or the like. In this case, although not particularly specified, the surface of the Pb-Sn alloy plating layer may be subjected to surface activation treatment using an alkali such as an aqueous solution of NaOH or the like when coating with a corrosion-resistant paint.
When a pretreatment such as a chemical conversion treatment using gold such as Cry or -H3PO4 aqueous solution is performed, the adhesion of the paint is significantly improved.

Aluminum, stainless steel, etc. are materials that have good corrosion resistance against alcohol, alcohol-containing twisters, alcohol oxides, gasoline, etc., and have electrical conductivity, and are coated with a Pb-Sn alloy plating layer to improve the corrosion resistance of the plating layer. and has the effect of improving weldability.

However, this effect is due to the nonvolatile content of resin-based paints that are difficult to dissolve in alcohol, alcohol oxides, and gasoline (good corrosion resistance), such as polytetrafluoroethylene and fluorinated ethylene globylene, such as aluminum and stainless steel. Copolymer, polyfluoroalkoxy resin, polychlorotrifluoroethylene, ethylene chlorotrifluoroethylene copolymer, ethylenetetrofluoroethylene copolymer, polyvinyl fluoride, polyvinyl fluoride.

Polyether sulfone, polymethylpetene.

? It is obtained when the coating vehicle contains one or more of resulfone and phenoxy resin in an amount of 30% or more by weight.

In addition, if the use is restricted to alcohol fuels, such as ethyl alcohol fuel or gasoline fuel mixed with 20 or less alcohol, epoxy (epoxy) may be used in addition to the above-mentioned resins.

One or more than 2 ft1 of phenol, 4-lyester resin may be used as the coating vehicle. In addition, the corrosion-resistant paint coating thickness in this case is
1 to 30μ is good. If the coating thickness is less than 1μ, weldability,
Although it is excellent in terms of workability, if the Pb-Sn alloy plating layer does not have a sufficient covering layer, the Pb-Sn alloy may dissolve from coating defects depending on the corrosive environment, making it impossible to obtain the desired corrosion resistance. There are cases. Further, if the coating film thickness exceeds 30 μm, defects such as partial peeling of the coating layer (powdering on the side) or difficulty in jointing may occur during molding. Among them, the most stable and problem-free are 2 to 15.
The coating thickness is μ.

The present invention provides the following excellent effects when a Pb-Sn alloy plated steel plate is coated with a corrosion-resistant paint and a large container is used with the coated surface facing the fuel such as gasoline on the contact side. .

The Pb-Sn alloy plating layer has better weldability than cold-rolled steel sheets, other surface-treated steel sheets, etc., and has extremely superior corrosion resistance against water, Ct-ions, etc. that can be contained in fuel.

Therefore, when exposed to a corrosive environment, moisture, Ct- ions, etc. that penetrate through the coating layer of the corrosion-resistant paint can cause Pb-8n
Even when reaching the all-gold plated surface, there are very few corrosion main components on the surface, so there is no paint film caused by corrosion main components (W small blisters (so-called blisters)), and the alcohol Paint adhesion (so-called secondary paint adhesion) even after long-term exposure to corrosive conditions containing moisture such as system fuels and gasoline
is ensured and the corrosion-resistant life is extended.

Furthermore, since the Pb-Sn alloy plating layer is soft and has a rich lubricating effect, good moldability can be obtained even if the surface is coated with the above-mentioned corrosion-resistant paint. in this way,
The present invention has good weldability and corrosion resistance against fuels such as alcohol, alcohol-containing fuel, and gasoline due to the mutual effect of the Pb-Sn alloy plating of the base plating layer and the coating layer of the corrosion-resistant paint applied to the surface. It is an excellent material for fuel containers.

Furthermore, the present invention provides one side of the above-described steel sheet of the present invention, that is, P
b - Aluminum on one side of Sn alloy plated steel plate.

The other surface of the present invention coated with a corrosion-resistant paint such as stainless steel, 2, KEL, etc. is coated with a Zn or Zn-based alloy plating layer or a Zn-based alloy plating layer.
Aluminum, nickel, cobalt, tin, chromium powder and one or two types of Zn-based alloy powder.

This is a steel plate coated with either a corrosion-resistant paint made by mixing one or more of iron powders or alloy powders thereof and containing the nonvolatile content of the paint.

In particular, when a fuel container is prepared using a surface plated with Zn or a Zn-based alloy as the outer surface of the fuel container, the outer surface has an anticorrosion effect, and the outer surface corrosion resistance of the container is significantly improved.

The Pb-Sn alloy plating layer itself has very good corrosion resistance, especially against Ct- ions, moisture, etc.

However, since the Pb-Sn alloy plating layer is cathodic in potential with respect to steel, the steel itself may be damaged by plating defects, scratches during forming, handling scratches, etc. that reach the base steel. There is a risk of perforation corrosion. Therefore, Ct-.

It has relatively good corrosion resistance against moisture etc. and has Pb-Sn
Zn, which is less potent (anodic) than the alloy plating layer
Or a plating layer of Zn-based alloy, or Zn or Zn
By coating the Pb-Sn alloy plating layer itself and the above-mentioned defects with a corrosion-resistant paint made by arbitrarily mixing the alloy with aluminum, nickel, etc. and containing the non-volatile content, it becomes possible to prevent corrosion of the Pb-Sn alloy plating layer itself and the defective areas mentioned above, and improve the outer surface of the fuel container. It significantly increases the corrosion resistance life against corrosion.

In the present invention, since all weldability is important, the amount contained in the Zn powder or Zn alloy powder relative to the nonvolatile components of the paint such as aluminum and nickel is limited. That is, in order to ensure the welding performance required for fuel containers, the content of Zn powder or Zn alloy powder is 60% of the nonvolatile content of the paint.
It is necessary that the content be at least 80 weight f- or more, preferably at least 80 weight f- or more.

Regarding the thickness of the coating layer, if the thickness is less than 1μ, the surface of the Pb-Sn alloy plating layer is likely to have non-coated areas, and sufficient corrosion protection effect may not be obtained, while if the thickness exceeds 30μ, the corrosion protection effect will be saturated. In addition, it may not be preferable in terms of weldability and workability.

The paint vehicle is not particularly specified, and the non-volatile components of the paint mentioned above may be used, and one or two types of acrylic resin, melamine resin, alkyd resin, etc.
! You may use the resin etc. which mixed the above.

(9) Pretreatment methods for coating are not particularly stipulated, but surface activation treatment using an alkali such as NaOH aqueous solution, chemical conversion treatment using CrO2, CrO2-H3PO4 aqueous solution, etc. , paint adhesion is improved.

There is no need to limit the coating method, and any commonly used method such as a roll coater or a curtain flow coater may be used.

According to the same law, the conditions for paint coating baking are 100 to 23
Depending on the type of paint, the type of curing agent added to the paint, and the coating thickness, it can be applied to the inner surface of the fuel container and the outer surface of the fuel container with a heating time of about 3 to 60 seconds at a temperature range of 0℃. It is arbitrarily selected and applied within the above conditions.

In addition, the coating floating type of galvanized layer or Zn alloy plated layer is
A thickness of 1 to 6 microns is desirable. In this case, the Zn alloy plating includes Zn~(8~20%) Ni type, Zn~(8~20%) Fe type, Zn-(8~20%)
0%) It is preferable to use a Co-based alloy plating composition.

Furthermore, the Zn or Zn alloy plating method is not particularly specified, but electroplating is advantageous. That is, Pb
- Since the Sn alloy plating layer has a low melting point, the Pb-Sn alloy plating layer will dissolve when immersed in a Zn or Zn alloy plating bath, so the hot-dip plating method is not preferable, and the electroplating method is used. It is better.

However, the Zn or Zn alloy plating layer "f, Pb-S
By applying it to the top surface of the N-alloy plating layer, it is extremely effective in preventing corrosion caused by sprayed salt for road anti-freezing, moisture, etc. from defective parts of the Pb-Sn alloy plating layer or from the eaves during processing. .

The present invention as described above improves the corrosion resistance of the inner surface of the fuel container by using a surface coated with a corrosion-resistant paint such as aluminum or stainless steel that exhibits excellent corrosion resistance particularly against alcohol, alcohol oxides, and gasoline. ensure,
At the same time, the surface of the Pb-Sn alloy plating layer is covered with a Zn plating layer, Zn alloy plating layer, or Zn powder, or a corrosion-resistant paint containing aluminum, nickel, etc., which has a sacrificial anticorrosion ability on the surface of the Pb-Sn alloy plating layer. By using it on the outer surface, the corrosion-resistant life of the container itself is extended, and in other words, the present invention has extremely excellent properties as a material for fuel containers.

During seam welding work in the manufacturing process of fuel containers,
Since the surface corresponding to the outer surface of the fuel container that comes into contact with the electrode is composed of an organic coating layer, a metal plating layer has better electrical conductivity, so it can be used over a wider welding range, and it is also easier to attach to the electrode. Since the kimono has less oxidation than organic coatings, the electrode has a long lifespan and continuous welding workability is better.

It is particularly preferable that the pigment in the coating layer applied to one side of the inner surface of the fuel container is an aluminum-tin mixed powder, an aluminum-nickel mixed powder, or an aluminum-tin-nickel mixed powder. This is particularly effective when the fuel container is attached to an automobile body in such a manner that a portion of the seam welded portion of the fuel container becomes the bottom.

When welding the painted surfaces on the inner surface of the fuel container together, the coating layer is ruptured by the pressure applied during welding, and the Pb of the coating layer and the underlying layer are ruptured.
- While electricity is applied to the Sn alloy plating layer and the steel base,
Each is melted and joined. In this case, in general, when the Pb-Sn alloy plating layer is melted and re-solidified in the welded part, the Pb-Sn plating layer does not necessarily spread uniformly and solidify in the same way as before melting. It often occurs that the exposed part of the steel base is the main component. Therefore, if a fuel container arrangement method in which these welds are located at the bottom is adopted, the separated water content (in %) of the fuel will be reduced.
Separation of water contained in a mixed fuel of alcohol and gasoline, separation of water contained in the case of using gasoline, etc.) may accumulate at the bottom and cause red rust to occur from the welded part. In such cases, by using a paint containing a mixture of aluminum, aluminum, and nickel, which have excellent coating effects, as a coating layer, you can ensure the coating effect of the coating layer on the other inner surface of the container, and also prevent the welding part from being damaged. When the paint is energized and melted to the molten metal of the Pb-Sn alloy plating layer, tin and nickel, which are metals with high mixed reactivity, are also supplied from the welded part of the coating layer, so the welded part This has the effect of suppressing the exposure of the steel base. As a result of various studies, it has been found that the above-mentioned improvement effect can be seen when the amount of tin, nickel, or a mixture thereof contained in aluminum is 5 or more, preferably 10 or more.

The present invention may be used with the coating structure as described above, or may be further coated with a coating after the fuel container is molded to decorate the outer surface of the fuel container. In the case of a zinc or zinc alloy plating layer, a chromate treatment or a phosphate treatment may be applied in advance as a base treatment for the coating, or may be applied after the fuel container is formed.

(Example) Examples of the present invention will be described below.

Example 1 A cold-rolled steel sheet was subjected to electrolytic degreasing and electrolytic pickling, and after surface cleaning and activation treatment suitable for surface treatment, after Nl plating with a thickness of 0.1μ, Pb-Sn alloy plating with a predetermined thickness was melted. This was done by plating method. After cooling, the Pb-8n alloy plated surface was subjected to a surface activation treatment for 5 seconds in a 5% NaOH aqueous solution at 50° C., and then the coating treatment shown in Table 1 was performed, and then each performance evaluation test was conducted.

As shown in Table 1, the inner surface of the tank of the present invention is made of aluminum.

If a paint containing nickel, tin, graphite, etc. is applied to the outer surface of the tank, or a paint containing Zn powder, Zn alloy (At, Cr-N1) powder, etc. It was found to be suitable. The performance evaluation test was conducted in the following manner.

■Evaluation Test The surface corresponding to the inner surface of the fuel container of the rectangular tube drawn material in (■) was filled with the fuel shown in Table 1 as the inside, and evaluation was made based on the rust occurrence after a standing test of 12 containers.

■ Blank size 500 x 500"' to height 1
20'''I square tube drawing process, scratches reaching the base metal are made on the outer wall part, and C of the following cycle is carried out.
C,T.

Test (Cyclic Corrosion Te5t
) f 60 cycles were performed, and the corrosion resistance was evaluated in terms of the depth of perforation at the scratch portion and the occurrence of red rust. C.C.,T.
All conditions are shown in Figure 1.

■ Fine stones with a diameter of 7 to 12+m at a pressure of 5kp/ctn
After 10 seconds of chipping as if hitting tcj toshikushi2i, 30? under the above cycle test conditions. A test was conducted on the engine and the occurrence of red rust from the chipping area was evaluated.

■ Blank size 0.8 x 500 x 500”
After applying lubricating oil, 150×1 with wrinkle presser pressure 30T.
Rectangular cylinder drawing was carried out with a 50" square inch, and evaluation was made based on the limit of the drawing depth and the occurrence of galling on the outer surface of the square cylinder drawing material.

■ Using a sample with a plate thickness of 0.8 m, welding speed was 2.5 m/min at a pressure of 400 #-f using a 41 m wide trapezoidal electrode.
, the welding time was 2-2'', and evaluation was made from the welding range, the main formation status of the nugget, and the appearance of the welded part. Using a Pb-Sn alloy plated steel plate with a composition formula of concentration, we applied the coating treatment to the inner surface of the fuel container as shown in Table 2@2, created a model vessel with the seam weld at the bottom, and Corrosion resistance was tested using the corrosion promoting solutions shown in Table 2.

Table 2 shows the results of aluminum.

When a paint containing nickel, tin, or a mixture thereof is used, its corrosion resistance is good.

For evaluation after the corrosion resistance test of the welded part on the inner surface of the tank bottom, cut out a 50mm wide specimen from the tank bottom, stretch it with a tensile tester, check for red rust near the welded part, and if there is red rust, cut the cross section. After polishing, we examined the depth of corrosion using a microscope and made a thorough evaluation.

In addition, evaluation was performed by measuring the presence or absence of red rust in areas other than welded areas and the depth of corrosion in the rusted areas.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing C, C, T, and test conditions in the example.噸、Challenge 2-

Claims (2)

[Claims] (1) Pb- containing Pb as the main component and 3% or more of Sn
Aluminum, stainless steel, nickel, cobalt, tin, chromium,
A weldable highly corrosion-resistant fuel container steel sheet coated with a corrosion-resistant paint containing one or more graphite powders or their alloy powders in an amount of 30% or more by weight based on the non-volatile content of the paint. (2) Pb-S mainly composed of Pb and containing 3% or more of Sn
Contains one or more of aluminum, stainless steel, nickel, cobalt, tin, chromium, graphite powders or their alloy powders in an amount of 30% or more by weight based on the non-volatile content of the paint on one side of the n-alloy plated steel plate. The other side is coated with a corrosion-resistant paint, and the other side is coated with a plating layer of Zn or Zn-based alloy, or one or two of Zn powder and Zn-based alloy powder, and powders of aluminum, nickel, cobalt, tin, chromium, and iron, or powders thereof. A weldable highly corrosion-resistant fuel container coated with a corrosion-resistant paint containing at least 60% by weight of the non-volatile content of the paint by mixing one or more types of alloy powder. steel plate.