KR20060047577A - Surface treated steel for fuel container - Google Patents

Abstract

Provided is a surface-treated steel sheet containing no lead and hexavalent chromium, which is suitable for fuel containers such as automobile gasoline tanks, which have excellent heat resistance gasoline resistance and weldability and press formability. On both surfaces of the galvanized steel sheet, a silicon film having a Si adhesion amount of 10 to 300 mg / m 2 is formed as a first layer. On the inner surface side of the container, an epoxy resin layer having a film thickness of 0.6 to 2.0 µm containing 5 to 60 parts by mass of a metal powder selected from Ni powder and ferrosilicon powder having an average particle diameter of 0.1 to 6.0 µm with respect to 100 parts by mass of the resin. Form. This second layer may further contain one or both of silica and wax. 1-40 mass parts of wax and 5-80 mass parts of silica in 100 mass parts of epoxy resins which have a functional group selected from a hydroxyl group, an isocyanate group, a carboxyl group, a glycidyl group, and an amino group on a container outer surface side A layer having a thickness of 0.3 to 2.0 µm containing parts is formed.

Description

Surface treated steel for fuel container

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet made of a zinc-based galvanized steel sheet, which is particularly suitable for a fuel container, which is a fuel tank of an automobile using gasoline as fuel. The surface-treated steel sheet of the present invention does not contain lead and hexavalent chromium, and has high corrosion resistance to deteriorated gasoline or alcohol-containing gasoline fuel (gasohol) containing organic acids, which is a problem on the inner surface side of the fuel tank. (Hereinafter also referred to collectively as "deteriorated gasoline resistance" including corrosion resistance to alcohol-containing gasoline fuel), and also excellent in resistance weldability and press formability.

Materials of fuel tanks for automobiles or motorcycles (hereinafter collectively referred to as automobiles) that use ordinary gasoline as fuel are required for corrosion resistance of the inner and outer surfaces, in particular, corrosion resistance, press formability, and weldability in the fuel environment on the inner surface side of the container. .

As a material for gasoline fuel containers, Pb-10-25% Sn alloy plated steel sheets, which are conventionally called turn sheets, have been widely used. However, recent environmental regulations have made it difficult to use turn sheets containing Pb, and development of surface-treated steel sheets for fuel containers has been demanded instead. In addition, the corrosion resistance to the fuel is required to a higher level, such as performance in a deteriorated gasoline environment including an organic acid generated by oxidation of the gasoline component is required.

In response to this demand, Al-plated steel sheets, Sn-Zn-plated steel sheets, and the like have been developed as substitutes. Among these, Al-plated steel sheet has a problem in joinability, such as welding and soldering. In this respect, Sn-approximately 8% Zn alloy-coated steel sheet is said to have a good performance balance, but since the use of the plating itself is almost limited to fuel containers, the market size is small, and there is a problem in terms of stable supply and price. have. Therefore, it is economically advantageous if a relatively low cost zinc-based galvanizing (" zinc-based plating " includes zinc plating and zinc alloy plating) steel sheets, which are generally widely used, can be applied to fuel containers.

As a technique of applying a Zn-based plated steel sheet to a fuel container use for automobiles, there is a Japanese Patent Application Laid-Open No. 10-137681 (Patent Document 1). This publication discloses a surface coated with an amine-modified epoxy resin layer containing Ni and Al metal powders on the inner surface side and a silica-containing resin layer containing wax on the outer surface side of the chromate-plated galvanized steel sheet. A treated steel sheet is proposed.

The surface-treated steel sheet of patent document 1 forms another resin layer in an inner surface and an outer surface after chromate-processing a galvanized steel plate. However, in recent years, too, due to environmental problems, there is a growing demand for not only the above-mentioned Pb but also materials that do not use the chromate treatment containing harmful hexavalent chromium, and further, non-chromium materials that do not contain chromium at all.

Japanese Patent No. 3328578 (Patent Document 2) applies a chemical conversion treatment such as chromate, zinc phosphate, or iron phosphate to one surface of the zinc-based plated steel sheet that contacts the inner surface of the fuel container, and further, Ni powder and Al powder. The surface-treated steel plate coated with the amine modified epoxy resin layer containing these is proposed. In Japanese Unexamined Patent Application Publication No. 2000-129461 (Patent Document 3), a first layer containing a resin and a silica source as a main film-forming component is formed on one surface of a zinc-based plated steel sheet, and Ni and a second layer are formed thereon. A surface-treated steel sheet having a resin layer containing a metal powder containing Al has been proposed.

(Patent Document 1) Japanese Unexamined Patent Application Publication No. 10-137681

(Patent Document 2) Japanese Patent No. 3328578

(Patent Document 3) Japanese Unexamined Patent Publication No. 2000-129461

However, in the above-mentioned prior art, since the thickness of the resin layer containing metal powder is 2-10 micrometers large, it is difficult to obtain stable weldability practically, and it was insufficient to use for manufacture of a fuel container.

In addition, since the outer surface side of the fuel tank is usually coated after press molding, even if the resin layer of the surface-treated steel sheet is damaged during press molding, corrosion resistance is rarely a problem. On the other hand, since it is common that the inner surface side is not coated after press molding, even if the resin layer is damaged by press molding, it is required to ensure corrosion resistance in a deteriorated gasoline environment. In the case of the conventional non-chromium material, in particular, if the chemical conversion treatment is zinc phosphate or iron phosphate, the corrosion resistance to the organic acid is insufficient, and the heat-resistant gasoline resistance after press molding is significantly reduced. In addition, it is preferable that both of the inside and the outside have good press formability and, therefore, lubricity so that damage of the resin layer during press molding is minimized.

An object of the present invention is to use a zinc-based galvanized steel as a base material, without using lead and hexavalent chromium, which is problematic in terms of the environment, excellent corrosion resistance in gasoline environment, particularly heat-resistant gasoline resistance, and excellent weldability More preferably, it is to provide a surface-treated steel sheet for fuel containers such as automobile gasoline containers, which is also excellent in press formability.

According to the present invention, a titration process is performed in which the plating surface of the zinc-based galvanized steel sheet does not contain hexavalent chromium, and on one surface side, a titration containing Ni metal powder and / or ferrosilicon powder having a specific particle diameter in the upper layer. A resin layer having a film thickness in the range is formed, and preferably, on the other surface side, by forming a resin layer excellent in lubricity, heat-resistant gasoline resistance and weldability are compatible, and a surface-treated steel sheet excellent in press formability is obtained.

In one aspect, the present invention is provided with at least one surface of a galvanized steel sheet, a first layer made of a silicon film containing no hexavalent chromium and a second layer thereon. The adhesion amount of one layer is 10-300 mg / m <2> as Si amount, and the said 2nd layer is a metal powder selected from Ni powder and ferro silicon powder of 0.1-6.0 micrometers of average particle diameters in 100 mass parts of binders which consist of a thermosetting organic resin. It is a surface-treated steel sheet for fuel containers characterized by being a metal powder-containing resin layer having a film thickness of 0.6 µm or more and less than 2.0 µm, in an amount of 1 to 60 parts by mass.

In another aspect, the present invention is provided with a silicon film containing no hexavalent chromium as a first layer and a second layer thereon on the plating surfaces of both surfaces of the galvanized steel sheet. As for the layer, the adhesion amount is 10-300 mg / m <2> as Si amount, and the said 2nd layer is Ni powder and ferro having an average particle diameter of 0.1-6.0 micrometer in 100 mass parts of binders which one side of a steel plate consists of a thermosetting resin A metal powder-containing resin layer having a thickness of 0.6 µm or more and less than 2.0 µm containing a metal powder selected from silicon powder in an amount of 1 to 60 parts by mass, and the surface on the opposite side of the steel sheet is a hydroxyl group, an isocyanate group, a carboxyl group, or a glyce 5 to 80 parts by mass of 1 to 40 parts by mass of wax and at least one selected from silica, titania and zirconia in 100 parts by mass of a binder composed of at least one organic resin having at least one functional group selected from a dill group and an amino group. A film surface-treated steel sheet for a fuel vessel, characterized in that a layer of thickness that 0.3~2.0㎛ oil.

The silicon film of the first layer is coated with a treatment liquid containing, as a main component, one or two or more silica sources (silica or its precursors) selected from aqueous silica, vapor phase silica, alkali metal silicate, alkoxysilane and alkyl silicate ester. What is formed by drying is preferable.

The said metal powder containing resin layer has 5-40 mass parts of at least 1 sort (s) chosen from (1) silica, titania, and zirconia, (5) 5-20 mass parts of wax, and (3) metal Al with respect to 100 mass parts of binders. You may further contain 1 or 2 or more components chosen from 1-30 mass parts of powder. In addition, thermosetting resin which is a binder of this metal powder containing resin layer becomes like this. Preferably it is an epoxy resin.

In this invention, the mass of a binder is the mass as solid content of the resin component used as a binder, and when the resin component used as a binder is a type thermosetting with a crosslinking agent, it is a total amount of resin and a crosslinking agent.

Best Mode for Carrying Out the Invention

[Material plated steel sheet]

The base material of the surface-treated steel sheet of this invention is a galvanized steel plate, ie, a galvanized steel plate or a zinc alloy plated steel plate, and it is preferable that it is a double-sided steel plate.

The steel plate of a plating material may be a general cold rolled steel sheet normally used. However, in the case of a fuel container, since it is generally subjected to severe molding, for example, it is an extremely low carbon steel, and is a steel sheet having excellent press formability, which is a component system containing one or two or more of Ti, Nb, and B added. desirable.

Plating to a steel plate is zinc or zinc alloy plating widely used for the purpose of ensuring corrosion resistance. Examples of the plating species include, but are not limited to, Zn, Zn-Al, Zn-Al-Si, Zn-Ni, Zn-Fe, Zn-Cr, Zn-Mg, Zn-Sn, Zn- Co etc. can be mentioned. Preferred is Zn-Ni alloy plating, which has the best balance of performance and economy. The Ni content of Zn-Ni alloy plating has preferable inside of the range of 11-14 mass%.

The plating method may be any of hot dip plating, electroplating, vapor deposition, and the like. The plating layer may contain a small amount of organic compounds such as an inhibitor, dextrin, and dextran. The plating adhesion amount is preferably 10 g / m 2 or more per side from the viewpoint of corrosion resistance. However, if the amount of adhesion is too large, it becomes a problem in terms of cost, workability and weldability. More preferable adhesion amount is 15-50 g / m <2> per side.

The surface-treated steel sheet of this invention forms the film of the 1st layer and 2nd layer demonstrated next in order on the surface (namely, on a plating layer) of at least one surface among the zinc-based galvanized steel sheets of a base material. This two-layer coating is usually formed on only one surface serving as an inner surface of the fuel container, and is subjected to a separate surface treatment on the surface on the opposite side.

[1st floor]

The first layer formed on the zinc-based plating layer is a silicon film that does not contain hexavalent chromium. As the silicon coating, a treatment liquid containing a silica source (colloidal silica or a precursor thereof) is used, and according to a conventional method, the treatment liquid is applied to the surface of the base metal plated steel plate, and then dried (or heat treated). Can be formed.

As the silica source, one or two selected from aqueous silica (also called silicasol, colloidal silica, etc.), gaseous silica (also called fumed silica, dry silica, etc.), alkali metal silicate, alkoxysilane, and alkyl silicate ester More than one species can be used.

Alkoxysilanes include n (n = 2-3) hydrolyzable groups (typically alkoxy groups, in particular methoxy or ethoxy groups) and (n-1) non-hydrolyzable oils in one atom of silicon. A device (for example, lower alkyl groups, such as ethyl and propyl, lower alkyl groups containing functional substituents, such as amino and epoxy, and a vinyl group) couple | bonded. Preferred alkoxysilanes used in the first layer in the present invention are those in which the non-hydrolyzable organic group is an alkyl group, for example, ethyltrimethoxysilane, propyltrimethoxysilane, ethyltriethoxysilane and the like. Alkoxysilanes, generally called silane coupling agents, in which the hydrolyzable organic group is an alkyl having a functional group or a vinyl group can also be used.

The silicic acid alkyl ester refers to a tetraalkoxy silane (= alkyl silicate), and specific examples thereof include ethyl silicate.

The alkoxysilane receives hydrolysis and polycondensation in the treatment liquid or in the coating and drying (heat treatment), and finally becomes a polysiloxane polymer. Similarly, the silicate alkyl ester is subjected to hydrolysis and polycondensation, and finally becomes a siliceous component. Therefore, even if any of the above silica sources are used, by coating and drying the above, a silicon-based film made of silica or having a polysiloxane structure in which some organic components remain, is formed as the first layer.

If the amount of deposition of the first layer is too small, the deterioration of the gasoline resistance is poor, and if too large, the weldability is inferior. As an appropriate adhesion amount, as an adhesion amount of Si contained in a 1st layer, it is about 10 mg / m <2> or about 30 mg / m <2> or less, and a more preferable range is 20-100 mg / m <2>.

In addition to a silicon compound, a 1st layer may contain some amount of resin, a phosphoric acid compound, etc. As resin, the thermoplastic resin which has 1 type (s) or 2 or more types, such as a hydroxyl group, a carboxyl group, an amino group, a glycidyl group, an isocyanate group, from the point of adhesiveness with a 2nd layer is preferable, As a resin type, for example, urethane And acrylic, polyester, epoxy, melamine resin and alkyd resin. By adding such resin, corrosion resistance improves. Moreover, phosphoric acid, phosphorous acid, hypophosphorous acid, and these alkali metal salts are mentioned as a phosphoric acid compound, Corrosion resistance improves by the addition. When including components other than these silicon compounds in a 1st layer, it is preferable that the quantity shall be 20 mass parts or less in total with respect to 100 mass parts of silica sources (amount as silica) in the resin liquid used for film formation.

[The second floor]

The surface-treated steel sheet of this invention is provided with the resin layer containing metal powder as a 2nd layer used as the uppermost layer on the said 1st layer. This 2nd layer (metal powder containing resin layer) uses thermosetting resin as a binder resin component, and contains one or both of Ni powder and ferrosilicon powder of predetermined particle diameter to this. Since this metal powder containing resin layer is especially excellent in heat resistant gasoline resistance, it is preferable to form in the inner surface side of a fuel container. Below, this metal powder containing resin layer may be called 2nd layer of an inner surface side for convenience.

It is preferable that a binder resin component exhibits the effect as a barrier with respect to a corrosive environment in addition to the role as a binder. For this purpose, the resin itself as a binder component is less likely to be dissolved and swelled in a gasoline environment. For this purpose, a thermosetting resin is more suitable than a thermoplastic resin. Examples of the thermosetting resin include epoxy resins, acrylic resins, urethane resins, polyester resins, phenol resins, and the like. In the present invention, epoxy resins are preferable. The epoxy resin may be a modified epoxy resin modified with functional groups such as an amino group. The binder resin component may further contain not only a thermosetting resin but a crosslinking agent as it becomes a base. As a crosslinking agent, a phenol resin, a melamine resin, benzoanamine resin etc. are mentioned, for example. The thermosetting resin is crosslinked and cured during the heat treatment of the coating to form a dense resin coating.

By containing 1 type or 2 types of metal powder selected from Ni powder and ferro silicon powder in the 2nd layer of an inner surface side, the heat resistant gasoline property and weldability of a surface-treated steel plate are improved. This is because there is an effect of neutralizing the organic acid contained in the deteriorated gasoline, and it is considered that the energization site suitable for welding is possible. In particular, since Ni powder is excellent in corrosion resistance with respect to alcohols, such as methanol, and the organic acid which is its oxide, and high specific resistance, it is effective also in weldability improvement, and is most suitable as an additive metal powder. Although the shape of Ni powder may be scaly shape, spherical particle is preferable. It is preferable to use the Ni powder and the ferro silicon powder whose average particle diameters are 0.1-6.0 micrometers. If the particle diameter is too small, the weldability is inferior. On the other hand, when too big | large, a resin layer will become porous easily, it will not only deteriorate heat-resistant gasoline property, but also the metal powder itself will precipitate easily at the time of coating, and it will become difficult to manufacture a uniform product. More preferable average particle diameter is 0.6-3.0 micrometers. In addition, this spherical particle can take the form of the aggregate in which several pieces are continuous in a linear state. In that case, the average short diameter of the aggregate falls within the above range.

The compounding quantity of the metal powder selected from Ni powder and ferrosilicon powder shall be in the range of 1-60 mass parts in total with respect to 100 mass parts of binders (as mentioned above, resin + crosslinking agent). When the amount of the metal powder is less than 5 parts by mass, the weldability and corrosion resistance are inferior. When the amount of the metal powder is greater than 60 parts by mass, the coating becomes porous and deteriorates gasoline resistance, and release of the metal powder occurs during press forming after the coating is formed. It becomes easy to do it. Moreover, since the fluidity | liquidity of a process liquid falls also, it becomes very difficult to apply | coat uniformly. A more preferable range is 10-40 mass parts.

The second layer on the inner surface side may further contain a metal Al powder in addition to the Ni powder and / or the ferrosilicon powder. Al powder is added mainly for the purpose of improving deterioration gasoline corrosion resistance. As described in Patent Literature 1, the shape of the Al powder is considered to be more preferable if the long diameter is in the shape of a scale having a diameter of about 10 to 20 µm, since a physical shielding effect on gasoline permeation can be expected. When adding metal Al powder, the quantity shall be 1-30 mass parts with respect to 100 mass parts of binders. When there is too much content of metal Al powder, a film will become porous and heat resistant gasoline resistance will deteriorate.

The second layer on the inner surface side further contains one or two or more kinds selected from silica, titania, and zirconia as necessary, such as waxes, colored pigments, antirust pigments, and conductive pigments, which are lubricants. You may do it.

Among these, since the silica, titania and zirconia components are effective for improving corrosion resistance, it is preferable to contain 1-40 mass parts in total in 1st layer with respect to 100 mass parts of binders. More preferably, it is 5-20 mass parts with respect to 100 mass parts of binders. These components are zirconium which is the above-mentioned silica source (aqueous silica, vapor phase silica, alkoxysilane, alkyl silicate ester, etc.) or a titanate coupling agent which is a titania source, and / or a zirconia source, in the resin liquid used for the film formation of a 2nd layer. By adding a cornate coupling agent etc., it can introduce | transduce in a 2nd layer.

If the 2nd layer contains wax, press formability will become high. When the wax is contained in the second layer for this purpose, the amount is preferably 5 to 20 parts by mass with respect to 100 parts by mass of the binder. As a wax, polyolefin wax, polytetrafluoroethylene, etc., such as polyethylene type, a polypropylene type, and a polybutene type, are preferable. One type of wax may be used, or several types may be mixed and used. As for the average particle diameter of a wax, 1-5 micrometers is preferable.

A 2nd layer can be formed by making into a processing liquid what fully suspended the said Ni powder and / or ferro silicon powder in the solution or dispersion liquid of a binder resin component, and apply | coating and drying (heat-processing) this. In the processing liquid, if necessary, the Al powder, silica, titania, zirconia components, waxes, and other additives as described above may be contained. However, the hexavalent chromium compound is not contained. The treatment liquid may be an aqueous treatment liquid in which the solvent is a mixed solvent of water or water and a water miscible organic solvent, or a solvent-based treatment liquid in which the solvent is an organic solvent.

Since the film thickness of a 2nd layer is too thick, weldability will fall, and too thin, heat-resistant gasoline property will fall, As an average film thickness, it is 0.6 micrometer or more and less than 2.0 micrometers, Preferably it is 0.8-1.8. It is set to micrometer. Depending on the particle diameter of the metal powder and the wax, the metal powder or the wax may protrude from the surface of the second layer. The film thickness in this invention is represented by the value which neglected in principle the part which protruded such a metal powder and a wax.

[The other side]

The surface-treated steel sheet of this invention can be equipped with the 2nd layer which consists of the above-mentioned silicon-like 1st layer and a metal powder containing resin layer on the plating surface of one side or both sides of a zinc-based galvanized steel plate. In the case where the first layer and the second layer are formed on both surfaces, at least one selected from wax and silica, titania, and zirconia is contained in at least the second layer of the surface which becomes the outer surface side of the fuel container, and the corrosion resistance of the outer surface side It is desirable to improve the lubricity.

When forming the said 1st layer and a 2nd layer only in one side, it is preferable to form the 2nd layer which consists of a metal powder containing resin layer excellent in heat resistant gasoline resistance on the inner surface side of a fuel container. Since the surface on the opposite side of the zinc-based galvanized steel sheet used as the outer surface side of the fuel container is generally coated, only the chemical conversion treatment (for example, formation of the same silicon film as the first layer) as the underlay is applied. You may carry out. However, it is preferable to form some coating on it again and to improve corrosion resistance in the corrosive environment (atmosphere and salt environment) different from an inner surface side.

For example, the surface on the opposite side of the zinc-based galvanized steel sheet may first be subjected to a base chemical conversion treatment (which may be the same as the first layer), and to be coated with one or more layers of excellent corrosion resistance (forming of a resin layer). Can be. Since the coating film thickness at this time is generally too thick, there is a possibility of deteriorating the weldability, it is determined so that the balance of corrosion resistance, weldability, and press formability is taken. Moreover, in order to improve weldability, you may contain a conductive pigment in a coating film.

In a suitable aspect of the present invention, the surface on the opposite side of the galvanized steel sheet is formed on the surface of the plated with a first layer as described above, that is, a silicon film containing no hexavalent chromium, and then waxed. And a second layer (hereinafter referred to as a second layer on the outer surface side) having excellent lubricity made of specific resin containing silica and silica is formed.

It is preferable that the 2nd layer of an outer surface side fulfills the function as a lubricating film which provides the sliding property at the time of press molding at the same time as the coating adhesiveness improves. For this purpose, it is preferable to use at least 1 sort (s) of resin which has at least 1 sort (s) of functional group chosen from hydroxyl group, isocyanate group, carboxyl group, glycidyl group, and amino group as an organic resin used as a binder. Thereby, paint adhesiveness can be improved. Specifically, an epoxy resin, an alkyd resin, an acrylic resin, a urethane resin, a polyvinyl butyral resin, a phenol resin, a melamine resin, etc. are mentioned. Among them, epoxy resins are most preferred as binders in terms of adhesion, aptitude to a post-coating step, and the like. Although an epoxy resin has a hydroxyl group and a glycidyl group, in order to introduce an amino group further, you may use the amino-modified epoxy resin.

As a wax, polyolefin wax, polytetrafluoroethylene, etc., such as polyethylene type, a polypropylene type, and a polybutene type, are preferable. One kind or two or more kinds of these waxes can be used. 1-5 micrometers is preferable and, as an addition amount, 5-40 mass parts is preferable with respect to 100 mass parts of binders (resin solid content) as an average particle diameter of a wax. When less than 1 mass part, lubricity runs short and press molding becomes difficult. On the other hand, when it exceeds 40 mass parts, the adhesiveness of a resin layer and adhesiveness with the coating performed after that fall.

At least one selected from silica, titania and zirconia is added to improve the corrosion resistance. When adding silica, any of a silica sol (aqueous silica) and a fumed silica (gas silica) may be sufficient. Moreover, the other silica source of the alkoxysilane and the alkyl silicate which were described about the 1st layer can also be used. The amount of silica added is preferably in an amount of 5 to 40 parts by mass as silica, and more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the binder. When adding titania and zirconia, it can introduce | transduce in a 2nd layer by adding the titanate coupling agent which is a titania source, and / or the zirconate coupling agent which is a zirconia source, etc.

In addition to resin and the said component, the organic resin paint for forming the 2nd layer of an outer surface side, as needed, additives, such as an antifoamer, a leveling agent, and coloring for improving paintability, Various pigments, such as titanium oxide, a burnt ocher, carbon black, a wet dispersing agent for improving the dispersion stability of a pigment, coupling agents, such as a silane coupling agent, a catalyst or crosslinking agent for promoting hardening reaction, etc. are well-known techniques. It is also possible to add by.

In addition, the second layer on the outer surface side may contain the metal powder, in particular the Ni powder and / or the ferrosilicon powder, and also the Al powder in the same manner as the second layer on the inner surface side described above, in which case the formed resin layer Is equivalent to the second layer on the inner surface side.

The film thickness of the 2nd layer film of an outer surface side shall be 0.3-2.0 micrometers. When the film thickness is less than 0.3 µm, the effect as the lubricity resin film of the second layer cannot be sufficiently obtained. When the film thickness exceeds 2.0 µm, the insulation of the second set is increased, and the weldability is lowered.

Although it is not necessary to apply an antirust oil to the surface of the surface-treated steel plate which concerns on this invention, or to apply lubricating oil at the time of shaping | molding process, it is preferable at the point of rust prevention at the time of storage, and the lubricity at the time of shaping | molding. Fuel containers, which are gasoline containers of automobiles, are generally manufactured by one- or multi-stage press molding and spot welding, including deep drawing molding. At this time, the surface whose 2nd layer is the above-mentioned metal powder containing resin layer shall be in the inner surface side of a container.

<Example 1>

In the present Example, the influence on the performance of the surface-treated steel sheet at the time of changing the kind and the film thickness of the silica source of a 1st layer was examined.

 [How to make an evaluation sample]

Formation of the first layer:

200 mm × of the above Zn-13% Ni alloy plated steel sheet (double-sided plating, coating weight: 20 g / m 2 per side) made of a cold rolled steel sheet having a thickness of 0.8 mm and including Ti, Nb, and B, which is extremely low carbon steel. After cut | disconnecting to 300 mm, the 1st layer was formed by apply | coating the process liquid which melt | dissolved or disperse | distributed the various silica source shown in Table 1 to one side, and dried at 60 degreeC. The coating method was a bar code method, and the order of the bar code and the concentration of the treatment liquid were adjusted so as to have a predetermined deposition amount. Adhesion amount was calculated | required by measuring the intensity | strength of Si in a 1st layer using the fluorescent X-ray apparatus.

Formation of the second layer:

On the first layer, the film thickness after the heat treatment was 1.0% of the treatment liquid prepared by suspending Ni metal powder (average particle size: 0.6 µm) in a solvent-based resin solution containing a thermosetting epoxy resin (molecular weight 20000). It applied by the bar code method so that it might become micrometer, and heat-processed at 220 degreeC after that. The mass ratio of resin and Ni metal powder was 100: 10.

[Assessment Methods]

Resistant Gasoline Resistance:

Cup drawing molding was performed so that the surface of a 2nd layer might become an inner surface on the following drawing conditions. Deteriorated gasoline was imitated in the obtained cup, 3 cc of aqueous solution with a formic acid concentration of 300 ppm, and 27 cc of gasoline were put and sealed, and it maintained at 45 degreeC. Evaluation was judged as follows in the corrosion product (liquid turbidity) situation after 30 days (to pass ○).

Drawing conditions: blank diameter = 100 mm, punch diameter = 50 mm, punch shoulder = 5R, dice diameter = 52 mm, dice shoulder = 5R, BH pressure = 10 kN, bulge height = 25 mm

Evaluation standard

◎ +: no change

◎: almost no change

(Circle): The turbidity generate | occur | produces about 10-40% from the top.

(Triangle | delta): The turbidity generate | occur | produces about 40 to 70% from the top (it is very difficult to observe the bottom),

X: Red rust floats almost in the whole liquid (it is very difficult to observe a bottom and a side).

Weldability (electrode resistance):

After the two feed sample materials were filled with the surface of the second layer inward, spot welding was carried out under the conditions of pressurization of 300 kgf, energization of 15 cycles, and current of 8 kA, and the resistance between the electrodes of the first cycle was measured. It evaluated together (to pass ○).

◎ +: Resistance between electrodes is 150 μΩ or less,

◎: resistance between electrodes is 200 μΩ or less,

(Circle): Resistance between electrodes is 200 microΩ or more, or hardness falls,

△: very large fall occurs,

X: It does not energize (impossible welding).

TABLE 1

 As the test results are shown in Table 1, the siliconized film of 10 mg / m 2 or more was formed as the Si adhesion amount of the first layer, and the heat resistant gasoline resistance was good. However, weldability was inferior to the thickness of a 1st layer exceeding 300 mg / m <2> as Si adhesion amount.

<Example 2>

In this example, the influence of the second layer base resin species was investigated.

[Formation of First Layer]

An electric Zn-coated steel sheet (double-sided plating, coating weight: 30 g / m 2 per side) made of the same cold-rolled steel sheet as that of Example 1 was used as the base material, and cut in the same manner as in Example 1, followed by bars on the same side. The 1st layer was formed by apply | coating by the code method and drying at 60 degreeC. The used silica source was aqueous silica (average particle diameter 7 nm), and adhesion amount was 30 mg / m <2> as Si.

[Formation of Second Layer]

A bar code was prepared so that the treatment liquid prepared by sufficiently suspending Ni metal powder (average particle diameter: 0.6 µm) in a solvent-based resin liquid containing several kinds of thermosetting resins was 1.0 µm on the first layer. It applied by the method and heat-processed at 220 degreeC after that. The mass ratio of resin and Ni metal powder was 100: 10.

[Assessment Methods]

The gasoline resistance and weldability were evaluated. The evaluation method is the same as that of Example 1. The results are shown in Table 2.

TABLE 2

As can be seen from Table 2, epoxy type thermosetting resin (molecular weight 20000), acrylic type thermosetting resin (molecular weight 15000), urethane type thermosetting resin (molecular weight 20000), polyester type thermosetting resin (molecular weight 20000), phenol type thermosetting resin Although any thermosetting resin, such as resin (molecular weight 20000), was able to satisfy the heat resistant gasoline resistance, the epoxy resin was especially excellent.

<Example 3>

In the present Example, the influence of the metal powder and other components added in a 2nd layer was examined.

[Formation of First Layer]

The first layer was formed in the same manner as in Example 2. The base material was the same electroplated Zn plated steel sheet.

[Formation of Second Layer]

Ni powder and / or ferrosilicon powder are added to a solvent-based resin liquid containing a thermosetting epoxy resin (molecular weight 20000), and some of them are in the case of a scale-like Al powder (long diameter 9 µm). Thus, aqueous silica was further added, and the suspension was sufficiently suspended as a treatment liquid. The treatment liquid thus prepared was applied on the first layer by a bar code method so that the film thickness after the heat treatment was 1.0 μm, and then heat treatment was performed at 220 ° C. The composition of the processing liquid is as shown in Table 3.

[Assessment Methods]

The gasoline resistance and weldability were evaluated. The evaluation method of heat resistant gasoline resistance is the same as that of Example 1. The results are also shown in Table 3.

TABLE 3

As can be seen from Table 3, by adding either or both of the Ni powder and the ferrosilicon powder, the deterioration of gasoline resistance and weldability was improved. Furthermore, the addition of Al powder and aqueous silica also showed good performance.

<Example 4>

In this example, the influence of the film thickness of the second layer was examined.

[Formation of First Layer]

The first layer was formed in the same manner as in Example 2. The base material was the same electroplated Zn plated steel sheet.

[Formation of Second Layer]

Except having changed the film thickness in various ways, it carried out similarly to Example 2, and formed the 2nd layer. The thermosetting resin used was an epoxy resin. After application, heat treatment was performed at 220 ° C. The composition of the treatment liquid and the film thickness of the inner surface second layer are as shown in the table.

[Assessment Methods]

The gasoline resistance and weldability were evaluated. The evaluation method is the same as that of Example 1, but weldability was evaluated also by the seam weldability test shown below other than the measurement of the interelectrode resistance similar to Example 1. The test results are summarized in Table 4.

Weldability (Seam Weldability):

Two supply test materials were superimposed so that a resin layer might come to a mating surface, 400m of continuous seam welding tests were performed on the following conditions, and the cross section microscopic observation of a 400m weld part was performed, and the following reference | standard evaluated.

Pressing force: 400kgf,

Current duration: 2 cycles

Idle time: 2 cycles

Current: 11000A,

Speed: 2.7 m / min.

Evaluation standard :

○: Good welding

△: blow hole

×: Beauty wearing oil

TABLE 4

As shown in Table 4, when the film thickness of the second layer was 0.6 µm or less, the deteriorated gasoline resistance was inferior. On the other hand, when the film thickness was 2.0 micrometers or more, weldability fell.

Example 5

In this embodiment, the surface-treated steel plate which formed the silicon film of the same 1st layer and the 2nd layer which differed on it on both surfaces of the steel plate is illustrated.

[1st floor]

b After cutting to 200 mm x 300 mm using the same Zn-13% Ni alloy plated steel sheet as described in Example 1, treating liquids containing aqueous silica (average particle size 7 nm) on both sides were prepared. The silicon film of the 1st layer was formed by apply | coating and drying at 100 degreeC. The coating method was the bar code method, and the order of the bar code and the concentration of the treatment liquid were adjusted so as to have a predetermined deposition amount. Adhesion amount was calculated | required by measuring Si intensity | strength with the fluorescent X-ray apparatus. On the first layer, as described below, the resin layers of the second layers different from each other on the inner side and the outer side were formed.

[The second layer of the inner surface side]

To a resin liquid containing an epoxy resin (molecular weight 10000), a component selected from wax (average particle diameter: 1 µm) silica (average particle diameter: 7 nm), Ni powder (average particle diameter: 0.6 µm), and ferrosilicon powder (average particle diameter: 3 µm) TiO ₂ (average particle diameter: 0.3 µm) as a component for measuring the film thickness and block isocyanate were added in various amounts as a crosslinking agent, and then suspended sufficiently to prepare a treatment liquid for forming a second layer. This process liquid was apply | coated by the bar code method on the said 1 layer of one side of the steel plate so that the film thickness after heat processing might be 1.4 micrometers, and it heat-processed at 220 degreeC after that. The film thickness was determined by measuring the intensity of Ti with fluorescent X-rays.

[The second layer of the outer surface side]

The coating liquid containing urethane-modified epoxy resin as a main component and the block isocyanate as a crosslinking agent is applied by a bar code method so as to have a film thickness of 0.6 µm, and heated for 60 seconds so as to have a plate temperature of 220 ° C. It bridge | crosslinked and the resin layer of the 2nd layer was formed.

 In addition to the resin and the crosslinking agent, polyethylene wax and coroidal silica were added in various amounts to the used coating liquid, and sufficiently stirred and dispersed before use. The film thickness was determined by measuring the intensity of Si with fluorescent X-rays.

The surface-treated steel sheet which had the coating structure different from the inner surface side and the outer surface side created in this way was investigated about the deterioration gasoline resistance and weldability by the method and evaluation criteria similar to Example 1. Moreover, the following tips were also examined about the adhesiveness of the resin layer (2nd layer) after shaping | molding, the moldability, and the post-coating corrosion resistance on the outer surface side.

[Adhesion of Resin Layer after Molding]

Cup molding is carried out under the same conditions as the heat-resistant gasoline test so that the evaluation surface is the outer surface, and an adhesive tape is attached to the inner surface side and the outer surface side of the processed portion, and then the tape is peeled off to determine whether or not the pigment is attached to the tape. It observed by eye and evaluated as follows (to ○ pass).

(Double-circle): Peeling is not recognized,

(Circle): Peeling is recognized a little,

X: Peeling is recognized clearly.

[Forming]

The Bauden test was done on condition of no coating and the load of 1 kgf, and it evaluated as follows by the initial kinetic coefficient of friction (passed to ○):

○: Initial kinetic friction coefficient is 0.20 or less

×: initial kinetic friction coefficient is 0.20 or more

 [Corrosion resistance after painting on the outer side]

On the resin layer (2nd layer) of an outer surface side, the alkyd melamine-type resin coating material (made by Japanese paint, a solvent type) was bar coded so that dry film thickness might be 15 micrometers, and it heat-processed at 120 degreeC. Then, the cross cut was put into the commercially available cutter, the salt spray (SST) test was performed, the width | variety which rust spreads was measured, and it evaluated as follows (it passes to ○).

◎: 2.5 mm or less width of rust,

○: 3.0 mm or less width of rust,

X: The width | variety of rust more than 3.0 mm.

(Test A)

In this test, the relationship between the deposition amount of the silicon film of the first layer and various performances is indicated. The test results are shown in Table 5.

The 2nd layer resin layer of an inner surface side is 1.4 micrometers, and contains 10 mass parts of wax, 15 mass parts of silica, and 10 mass parts of Ni powder with respect to 100 mass parts of binders.

The 2nd layer resin layer of the outer surface side is 0.6 micrometer in film thickness, and contains 10 mass parts of wax and 15 mass parts of silica with respect to 100 mass parts of binders.

TABLE 5

In Table 5, the adhesion amount of Si of the first layer is preferably in the range of 10 to 300 mg / m 2, and more preferably in the range of 20 to 100 mg / m 2.

(Test B)

This test shows the relationship between the content of silica, wax and metal powder of the second layer resin layer on the inner surface side and all performances. The film thickness and composition of the second layer resin layer on the outer surface side were the same as those in Test A. The test results are shown in Table 6.

TABLE 6

As shown in Table 6, the moldability is improved by adding wax to the second layer resin layer on the inner surface side, the corrosion resistance and weldability are improved by adding Ni powder, and the weldability is improved by adding the silicon powder. It became.

(Test C)

This test shows the relationship between the amount of each component added on the outer surface and all performance. The film thickness and composition of the inner layer side second resin layer were the same as those in Test A. The experimental results are shown in Table 7.

TABLE 7

As shown in Table 7, although corrosion resistance improved by adding a silica to the 2nd layer resin layer of an outer surface side, 10-30 mass parts per 100 mass parts of binders were the most preferable as addition amount.

According to the present invention, a zinc-based plated steel sheet is used as a base material and contains no lead or hexavalent chromium, which are harmful to the environment, and various performances required for fuel containers for automobile gasoline, in particular, gasoline resistance and press formability. And a low cost surface treated steel sheet excellent in weldability.

Claims (7)

On the plating surface of at least one surface of a galvanized steel plate, the 1st layer which consists of a silicon film which does not contain hexavalent chromium, and the 2nd layer on it are provided, and the adhesion amount of the said 1st layer is a Si amount. 10-300 mg / m <2>, and the said 2nd layer is the quantity of 1-60 mass parts of metal powder selected from Ni powder and ferro silicon powder which have an average particle diameter of 0.1-6.0 micrometer in 100 mass parts of binders which consist of a thermosetting organic resin. A surface-treated steel sheet for a fuel container, which is a metal powder-containing resin layer having a film thickness of 0.6 µm or more and less than 2.0 µm. On the plating surfaces of both surfaces of the galvanized steel sheet, a silicon film containing no hexavalent chromium as a first layer and a second layer thereon are provided, and the adhesion amount of the first layer is 10 to 300 mg as the amount of Si. / M 2, and the second layer is one to 60 parts by mass of a metal powder selected from Ni powder and ferro silicon powder having an average particle diameter of 0.1 to 6.0 μm in 100 parts by mass of a binder made of a thermosetting resin. A metal powder-containing resin layer having a thickness of 0.6 µm or more and less than 2.0 µm, which is contained in a negative amount, and the surface on the opposite side of the steel sheet has at least one functional group selected from hydroxyl group, isocyanate group, carboxyl group, glycidyl group and amino group. The branch is a layer having a film thickness of 0.3 to 2.0 µm, which contains 1 to 40 parts by mass of wax and at least 5 to 80 parts by mass selected from silica, titania, and zirconia in 100 parts by mass of a binder made of at least one organic resin. A surface-treated steel sheet for fuel containers. 3. The silicon film of the first layer is composed mainly of one or two or more silica sources selected from aqueous silica, vapor phase silica, alkali metal silicates, alkoxysilanes, and alkyl silicate esters. The surface-treated steel sheet for fuel container formed by application | coating and drying of a process liquid. The fuel according to any one of claims 1 to 3, wherein the metal powder-containing resin layer further contains at least one selected from silica, titania, and zirconia in an amount of 5 to 40 parts by mass with respect to 100 parts by mass of the binder. Surface-treated steel sheet for containers. The surface-treated steel sheet for fuel container according to any one of claims 1 to 4, wherein the metal powder-containing resin layer further contains 5 to 20 parts by mass of wax with respect to 100 parts by mass of the binder. The surface-treated steel sheet for fuel container according to any one of claims 1 to 5, wherein the metal powder-containing resin layer further contains 1 to 30 parts by mass of metal Al powder with respect to 100 parts by mass of the binder. The surface-treated steel sheet for fuel container according to any one of claims 1 to 6, wherein the thermosetting resin is an epoxy resin.