JP2006291246A - Surface-treated plated steel sheet suitable for fuel container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-treated plated steel sheet having one layer of a coating thereon free from chromium and lead, which retains superior corrosion resistance and resistance to deteriorated gasoline even after having been alkaline-degreased, has adequate solderability (brazing property), post-coating property, weldability, adhesiveness with an adhesive and formability, and is suitable for surface treatment for inner and outer surfaces of a fuel tank. <P>SOLUTION: This surface-treated plated steel sheet has a film on at least one surface of the zinc-nickel alloy plated steel sheet formed by the steps of: preparing a water-based surface treatment agent containing a cationic urethane resin (A), a particular cationic phenol resin (B), phosphoric acid (C), a titanium compound (D), a vanadium compound (E) and a wax-based lubricant (F) as components; applying the agent on the surface; and drying it. Ratios of the components in the surface treatment agent are, by pts.mass, 40 to 55 for (A), 15 to 25 for (B), 3 to 10 in P terms for (C), 0.5 to 3 in Ti terms for (D), 0.5 to 3 in V terms for (E) and 3 to 10 for (F). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface-treated plated steel sheet that does not use chromium at all, which is suitable for use as a material for fuel containers, particularly automobile fuel tanks that use gasoline as fuel.

  Pb-Sn alloy-plated steel sheet called turn plating has been widely used as a material for a general fuel tank for automobiles that uses gasoline as fuel. However, a material that does not contain Pb has been required due to environmental problems. ing. Further, with respect to the corrosion resistance to fuel, a higher level is required, for example, corrosion resistance to deteriorated gasoline containing an organic acid (hereinafter, sometimes simply referred to as “gasoline resistance”) is required.

  In response to this demand, Al-plated steel sheets (for example, Patent Document 1), Sn—Zn alloy-plated steel sheets (for example, Patent Document 2), and the like have been developed as alternatives. Among these, the Al-plated steel sheet has a problem in joining properties such as welding and soldering, and a processing manufacturer or the like desires a material that is easier to use than can be easily joined. On the other hand, Sn-approx. 8% Zn alloy-plated steel sheet is said to have a good balance of performance, but the use of this alloy plating is limited to only fuel tanks, which increases the cost in terms of productivity. , There is an economic problem.

  In this respect, it is economically advantageous if such Zn plating (Zn plating and Zn alloy plating), which is widely used, can be applied to automobile fuel tank applications, and there is such a movement.

  As a conventional technique in which a Zn-based plated steel sheet is applied to an automotive fuel tank, Patent Document 3 discloses a resin containing Ni and Al metal powder on the tank inner surface side of the Zn-based plated steel sheet and wax on the outer surface side. A surface-treated steel sheet coated with a resin has been proposed.

  This surface-treated steel sheet is obtained by applying the above resin after chromate-treating a Zn-based plated steel sheet. The chromate film formed by the chromate treatment contains hexavalent chromium as described in this publication. In the case of surface-treated steel sheets that use Zn-based plated steel sheets as the base material, chromate treatment containing hexavalent chromium is extremely effective in ensuring corrosion resistance, so it is an important safety part for automobiles such as fuel tanks. For applications that require high corrosion resistance, it was common to perform chromate treatment. However, recently, due to environmental problems, there is an increasing demand for materials that do not contain hexavalent chromium. Therefore, there is an urgent need to develop a surface-treated plated steel sheet for automobile fuel tanks that does not contain hexavalent chromium.

  As a surface-treated plated steel sheet for a fuel container that does not contain hexavalent chromium, for example, in Patent Document 4, a layer mainly composed of a silicate compound and a resin is formed on both surfaces of a zinc-based plated steel sheet, and an upper layer is formed on the inner surface side. A technique has been proposed in which a thermoplastic resin is formed as an upper layer on the outer surface side of a resin film containing metal powder made of Ni, Al, or an alloy thereof, if necessary. However, this technique requires two layers of coating and is disadvantageous in terms of cost.

  In recent years, further performance has been required for surface-treated steel sheets for fuel containers. For example, after a plated steel sheet is pressed and formed into a fuel tank shape, it is often washed with an alkaline degreasing agent for the following reason. The lubricating oil applied to the plated steel sheet during the forming process serves to assist the forming process. However, when it is used as a fuel tank after that, it does not require lubricating oil, and it may contaminate the fuel or interfere with the subsequent work such as soldering, bonding and welding. Remove the lubricant along with dirt adhering to the surface. Previously, cleaning could be easily performed in a short time using a chlorinated organic solvent such as trichlene, but as is well known, chlorinated organic solvents are legally regulated substances from the viewpoint of environmental protection, and replacement is urgent. ing. Therefore, an alkaline degreasing agent has been used as an alternative cleaning agent. For this reason, it has been demanded that the surface-treated steel sheet still maintains a predetermined performance even after washing with an alkaline degreasing agent, that is, has excellent alkali resistance.

As a one-layer treatment not containing chromium, Patent Documents 5 and 6 propose a treatment with an ionic organic resin, a specific phenol-based resin, and a water-based surface treatment agent containing a metal compound. However, it has been found that the surface treatment agent disclosed therein does not always provide sufficient performance with respect to alkali resistance, gasoline resistance against deteriorated gasoline, and corrosion resistance.
Japanese Patent Laid-Open No. 10-46358 JP-A-8-269733 Japanese Patent Application Laid-Open No. 10-137681 JP 2000-129461 A JP 2001-181860 A JP 2003-13252 A

The performance required for the surface-treated steel sheet for automobile fuel tanks differs between the inner surface side and the outer surface side of the tank.
On the inner surface side of the tank, corrosion resistance to gasoline, particularly deteriorated gasoline containing an organic acid such as formic acid is most important. Moreover, the alkali resistance that performance does not deteriorate after washing with an alkaline degreasing agent is also important.

  On the other hand, the characteristics required on the outer surface side include solderability, post-paintability at a processing manufacturer, weldability, adhesiveness with an adhesive, and the like. If the performance required on the outer surface side can be satisfied, the same surface treatment can be performed on both the inner and outer surfaces, and the productivity of the surface-treated plated steel sheet is increased, which is further preferable.

  The present invention is a single layer coating type surface-treated plated steel sheet suitable for automobile fuel tanks that does not contain environmentally problematic lead and hexavalent chromium. It aims at providing the steel plate which can be satisfy | filled.

  The present inventors have found that the above-mentioned problems can be solved by forming a film on the surface of a zinc-nickel alloy-plated steel sheet by applying and drying a specific aqueous surface treatment agent. Reached.

  Here, the present invention provides a polymer molecule having an average degree of polymerization of 2 to 50 having a cationic urethane resin (A) and a repeating unit represented by the following general formula (1) on at least one surface of a zinc-nickel alloy plated steel sheet. Application of a water-based surface treatment agent containing, as components, a cationic phenol resin (B) comprising: phosphoric acid (C); a titanium compound (D); a vanadium compound (E); and a lubricant (F). A surface-treated plated steel sheet having a film formed by drying, wherein the component ratio in the surface treatment agent is (A) 40 to 55 parts by mass, (B) 15 to 25 parts by mass, and (C) P conversion 3-10 parts by mass, (D) 0.5-3 parts by mass in terms of Ti, (E) 0.5-3 parts by mass in terms of V, (F) 3-10 parts by mass It is a treated plated steel sheet.

In the formula, Y ₁ and Y ₂ each independently represent a hydrogen atom or a Z group represented by the following formula (2) or formula (3).

R ₁ , R ₂ , R ₃ , R ₄ and R ₅ in formula (2) and formula (3) are each independently a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₁ -C ₁₀ hydroxyalkyl. The average substitution number of the Z group per benzene ring in the polymer molecule is 0.2 to 1.0.

Preferably the coating weight of the coating is in the range of 500 to 2000 / m ^2. The present invention also relates to a fuel container manufactured from the above-mentioned surface-treated plated steel sheet and having the coating only on the inner surface or both the inner surface and the outer surface.

The surface-treated plated steel sheet of the present invention is required for the inner surface of the fuel tank, has excellent corrosion resistance against gasoline, particularly deteriorated gasoline, and has excellent alkali resistance, and retains gasoline resistance performance even after washing with an alkaline degreasing agent. Yes. This surface-treated plated steel sheet is also excellent in solderability, post-coating properties, weldability, adhesiveness with adhesives, and formability required on the outer surface side of the fuel tank.

Therefore, the surface-treated plated steel sheet of the present invention is suitable as a material for gasoline fuel containers, and is suitable for fuel tanks for automobiles, motorcycles, tractors, etc., portable fuel tanks, and the like. In addition, the single-layer coating type is advantageous in terms of cost. Furthermore, the same surface treatment can be performed on both the inner and outer surfaces, and in this case, productivity is improved.

The present invention will be specifically described below. In the following description, “%” and “parts” are “% by mass” and “parts by mass” unless otherwise specified.
The steel sheet used as the plating base material in the surface-treated plated steel sheet according to the present invention may be a commonly used cold-rolled steel sheet. However, in fuel tank applications, since generally severe forming is performed, it is excellent in press formability such as a component system in which one or more of Ti, Nb, and B are added, for example, extremely low carbon steel. A steel plate is preferred.

  The plating applied to the steel sheet is made of zinc-nickel alloy plating that is excellent in corrosion resistance because corrosion resistance is important for the purpose of the present invention. The nickel content in the zinc-nickel alloy plating film is preferably in the range of 5 to 17%.

The plating method is preferably an electroplating method, and the plating bath used may contain a small amount of an organic compound such as an organic inhibitor, dextrin or dextran in addition to the zinc compound and the nickel compound. The plating adhesion amount is preferably 10 g / m ² or more per side from the viewpoint of corrosion resistance. If the amount of adhesion is too large, there will be a problem in terms of cost and workability, so a more preferable amount of adhesion is 15 to 50 g / m ² per side.

  A film is formed on at least one surface of the zinc-nickel alloy plated steel sheet by applying and drying an aqueous surface treating agent containing the components (A) to (F). As described above, this film is excellent in corrosion resistance, particularly gasoline resistance, and alkali resistance, and also has good solder (brazing) property, post-coating property, weldability, and adhesiveness. Accordingly, the aqueous surface treatment agent may be applied to both surfaces of the plated steel sheet so that both the inner surface and the outer surface of the fuel tank have this film, or so that only the inner surface side of the fuel tank has this film. The aqueous surface treatment agent may be applied only to one side of the plated steel sheet.

  The cationic urethane resin (A) plays an important role in forming a dense film, and is important in obtaining excellent gasoline resistance and alkali resistance. The cationic urethane resin (A) is a polycondensate of a polyol and an aliphatic, alicyclic or aromatic polyisocyanate, and is used in the form of a water-soluble resin or an aqueous emulsion resin.

  Examples of the polyol include polyethylene glycols such as diethylene glycol and triethylene glycol, and polyether glycols such as polyethylene / propylene glycol. In addition, polyester polyol, polycarbonate polyol, and the like can be used. In order to make the resin cationic and to impart water solubility or water emulsification, a part of the polyol component is a polyol having a (substituted) ammonium group.

  Examples of the aliphatic, alicyclic or aromatic polyisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

  The weight average molecular weight of the cationic urethane resin (A) is preferably 1,000 to 1,000,000, and more preferably 2,000 to 500,000. When the average molecular weight is too small, the film forming property is insufficient, and when it is too large, the stability of the treatment agent tends to be lowered.

  The cationic urethane resin (A) is contained in an amount in the range of 40 to 55 parts. This component ratio is preferably in the range of 44 to 51 parts. If the amount is too small, the alkali resistance and gasoline resistance are lowered. If the amount is too large, the adhesiveness tends to be lowered in addition to the above performance.

  The cationic phenol resin (B) is a basic component constituting the film together with the cationic urethane resin (A). Furthermore, it plays an important role in enhancing the adhesiveness with the adhesive. The cationic phenol resin (B) is an oligomer or polymer having a polymer molecule having a repeating unit represented by the general formula (1) and having an average degree of polymerization (n) of 2 to 50.

In the formula, Y ₁ and Y ₂ which can be bonded to any position of the benzene ring each independently represent a hydrogen atom or a Z group represented by the following formula (2) or formula (3).

R ₁ , R ₂ , R ₃ , R ₄ and R ₅ in formula (2) and formula (3) are each independently a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₁ -C ₁₀ hydroxyalkyl. The average substitution number of the Z group per benzene ring in the polymer molecule is 0.2 to 1.0.

If the number of carbon atoms of the substituents R _{1 to} R ₅ present in the Z group becomes too large, the film-forming property of the treatment liquid will decrease, so the surface-treated plated steel sheet will not have sufficient gasoline resistance, top coatability, etc. become. The number of carbon atoms of this substituent is preferably 1 to 6, more preferably 1 to 4, and particularly preferably 1 to 2.

  When the average degree of polymerization (n) of the cationic phenol resin (B) is less than 2, the film formability deteriorates, so the gasoline resistance and the alkali resistance are inferior. descend. This average degree of polymerization (n) is preferably 4 to 40, more preferably 8 to 20.

  When the average number of substitutions of Z groups per benzene ring of the cationic phenol resin (B) is less than 0.2, the adhesion of the resin to the substrate surface becomes insufficient and the paintability is deteriorated. Further, if this average number of substitution exceeds 1.0 (that is, on average, more than one Z group is substituted on each benzene ring), the hydrophilicity of the resin becomes too large, and the treated zinc-based plated steel sheet Corrosion resistance is insufficient. The average number of substitutions is preferably 0.3 to 0.7. When the substituent is an ionic ammonium group represented by the formula (3), the average number of substitution is preferably less than 0.5.

  The cationic phenol resin (B) is present in an amount ranging from 15 to 25 parts. This component ratio is preferably in the range of 18-22 parts. If it is less than 15 parts, the adhesiveness is lowered, and if it exceeds 25 parts, alkali resistance and gasoline resistance are lowered.

  Phosphoric acid (C) is effective for improving the corrosion resistance of the film. As the type, orthophosphoric acid, phosphorous acid, hypophosphorous acid, and polyphosphoric acid are preferable. The amount of phosphoric acid (C) is in the range of 3 to 10 parts, preferably 5 to 8 parts in terms of P. If the amount is too small, the corrosion resistance tends to decrease. If it is too much, the adhesiveness is lowered.

The titanium compound (D) is also effective in improving the corrosion resistance of the film. The type is not particularly limited as long as it is soluble in the aqueous surface treatment solution. Examples of suitable titanium compounds include titanyl sulfate (TiOSO ₄ ), titanium hydrofluoric acid, diisopropoxytitanium bisacetylacetone {(C ₅ H ₇ O ₂ ) ₂ Ti [OCH (CH ₃ ) ₂ ] ₂ }, lactic acid And a reaction product of titanium alkoxide, titanium lactate, titanium acetylacetonate and the like. The amount of the titanium compound (D) is in the range of 0.5 to 3 parts, preferably in the range of 1 to 2.5 parts in terms of Ti. Either too little or too much leads to a decrease in corrosion resistance (gasoline resistance, alkali resistance).

The vanadium compound (E) is also effective in improving the corrosion resistance of the film. As long as it is soluble in the aqueous surface treatment solution, the type is not particularly limited. Examples of suitable vanadium compounds include vanadium pentoxide (V ₂ O ₅ ), metavanadate (HVO ₃ ), ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride (VOCl ₃ ), vanadium trioxide (V ₂ O ₃ ), vanadium dioxide (VO ₂ ), vanadium oxysulfate (VOSO ₄ ), vanadium oxyacetylacetonate [VO (OC (═CH ₂ ) CH ₂ COCH ₃ ) ₂ ], vanadium acetylacetonate [V (OC (= CH ₂ ) CH ₂ COCH ₃ ) ₃ ], vanadium trichloride (VCl ₃ ) and the like. The amount of the vanadium compound (E) is in the range of 0.5 to 3 parts in terms of V, preferably in the range of 1 to 2.5 parts. Either too little or too much leads to a decrease in corrosion resistance.

  It is important to use both a titanium compound (D) and a vanadium compound (E) as the metal compound in order to ensure both gasoline resistance and alkali resistance. If only one of them is used or if one of them is replaced with another metal compound, both gasoline resistance and alkali resistance become insufficient.

  Lubricant (F) is effective for improving the lubricity of the composite film and for preventing plating wear and the like when molding the fuel tank. Furthermore, if the shape is not complicated, non-lubricated molding that does not require the lubricating oil used in the molding process is possible. Accordingly, the lubricant (F) is contained in the surface treatment agent.

  As the lubricant (F), a lubricant that can be dispersed in an aqueous surface treatment solution is used. Examples of suitable lubricants are water-based emulsion type waxes such as polyolefin waxes, ester waxes and hydrocarbon waxes. The amount of lubricant (F) is in the range of 3 to 10 parts, preferably in the range of 5 to 8 parts.

For any of the above components, one or more materials can be used, and when two or more materials are used, the total amount may be within the range of the above component ratio.
Moreover, the values of the above component ratios (A) to (F) are not based on any component, nor are the totals being 100 parts by mass. It is sufficient that the ratio of these components can be expressed within the range of the above component ratio.

  The pH of the aqueous surface treatment agent used in the present invention is preferably in the range of 2.0 to 5.0. Thereby, since the plating surface of a zinc-nickel alloy plating steel plate is etched by a surface treating agent, the adhesiveness to the plating surface of the membrane | film | coat formed can be improved.

  The aqueous surface treatment agent may further contain components other than those described above as long as the film performance is not significantly adversely affected. Examples of such components include other aqueous resins, silane coupling agents, surfactants, pH adjusters (acid or base), antifoaming agents, and the like. In particular, when the film is formed on only one surface, the film may be colored by adding a coloring component to the surface treatment agent in order to easily identify the film forming surface.

  The aqueous surface treating agent of the present invention is applied to one side or both sides of a zinc-nickel alloy plated steel sheet and then dried to form a film on the surface. This film forms a composite film containing two kinds of resins and metal compounds as film forming components. The coating method is not particularly limited, and any coating method that can control the adhesion amount can be employed. For example, a roll coat method in which a treatment agent is transferred to a roll and applied, a method of squeezing with a roll after pouring by a shower ringer or the like, a method of draining with an air knife, a dip coating method of immersing in a treatment agent, a treatment agent A spraying method for spraying is generally used.

  Drying is preferably performed at a temperature at which the maximum steel sheet temperature is 50 to 250 ° C. The heating means for drying is not particularly limited, and a heating furnace may be used or heating may be performed by hot air heating. The heating time depends on the heating temperature and the amount of treatment agent attached, and may be selected so that a dry film can be obtained.

  Thus, a chromium-free coating with excellent corrosion resistance is formed on at least one surface of the base zinc-nickel alloy plated steel sheet. The fuel container having this coating on the inner surface is excellent in gasoline resistance and alkali resistance, and exhibits excellent corrosion resistance in a deteriorated gasoline environment even after alkali degreasing. On the other hand, the performance required for the outer surface side of the fuel container, such as weldability, solderability, brazing property, and adhesion, is usually better when there is no film. However, when corrosion resistance is required also on the outer surface side, the coating according to the present invention may be formed on both the inner surface side and the outer surface side. The coating according to the present invention has good weldability, soldering (brazing) properties and adhesion required on the outer surface side, and even if there is a coating, these performances are not significantly impaired.

The preferable adhesion amount (per one side) of the film is in the range of 500 to 2000 mg / m ² , more preferably in the range of 800 to 1500 mg / m ² . If the amount of adhesion is small, the corrosion resistance (alkali resistance, gasoline resistance) tends to be inferior. If the amount is too large, the cost increases, and weldability, brazeability, solderability, and adhesion tend to deteriorate.

  It is not always necessary to apply rust-preventive oil to the inner and outer surfaces of the surface-treated plated steel sheet according to the present invention, or to apply lubricating oil at the time of forming, but it is necessary to prevent rust during storage and lubricity during forming. Desirable in terms.

The effect regarding the surface-treated plated steel sheet of the present invention will be specifically illustrated with Examples. The examples are given for illustration of the invention and are not intended to limit the invention in any way.

(Example 1)
Surface treatment agent The composition of the components of the aqueous surface treatment agent used in the present invention examples and comparative examples is shown in Table 1. In Table 1, the surface treatment agents 14 to 19 are comparative surface treatment agents that do not contain any of the components (A) to (E), and the surface treatment agents 20 and 21 are made of the urethane resin (A). It is a comparative surface treating agent whose component ratio is outside the scope of the present invention. Each aqueous surface treatment agent was prepared such that the solid content concentration was 10%.

The components (A) to (F) used are as follows.
Cationic urethane resin (A)
A1: Cationic polyurethane resin (Adekabon titer HUX-670 manufactured by Asahi Denka),
A2: Cationic polyurethane resin (Daiichi Kogyo Seiyaku Superflex 600).

Cationic phenolic resin (B)
B1: n = 5, Y ₁ = −CH ₂ N (CH ₃ ) ₂ , Y ₂ = H, Z substitution degree = 0.5,
_{B2: n = 10, Y 1} = -CH 2 N (CH 3) (C 2 H 4 OH), Y 2 = H, Z substitution degree = 1.0.

Phosphoric acid (C)
C1: orthophosphoric acid
C2: hypophosphorous acid.

Titanium compound (D)
D1: titanium sulfate,
D2: titanium hydrofluoric acid,
D3: Titanium lactate
D4: Titanium acetylacetonate.

Vanadium compound (E)
E1: Vanadium pentoxide,
E2: vanadium oxysulfate,
E3: vanadyloxyacetylacetonate,
E4: ammonium metavanadate.

Lubricant (F)
F1: Polyethylene wax (particle size 1 μm, molecular weight 3000),
F2: Polypropylene wax (particle size 1 μm, molecular weight 2000).

A 0.8-mm-thick electric Zn-13% Ni alloy-plated steel sheet (double-sided plating, plating adhesion amount: 30 g / m ² per side) cut to 250 mm × 310 mm was used as a base-plated steel sheet. Using a roll coater, the aqueous surface treatment agent shown in Table 1 was applied to both surfaces of this plated steel sheet so as to have a film adhesion amount (adhesion amount per one surface) as shown in Table 2, and shown in Table 2 It dried with the drier so that it might become the highest plate | board temperature, and obtained the surface treatment plating steel plate for a test.

Various performances of the obtained surface-treated plated steel sheet were evaluated by the following test methods. The test results are also summarized in Table 2.
Gasoline resistance Under the drawing conditions described later, cup drawing was performed so that the surface-treated side became the inner surface, and the resulting cup was sealed with simulated deteriorated gasoline obtained by adding 10 cc of a formic acid aqueous solution with a concentration of 3000 ppm to 20 cc of gasoline, Maintained at 50 ° C. Evaluation was judged as follows in the state of the corrosion product (liquid mist) after 300 days (up to ◯ passed).

◎: Almost no change;
○: Generation of dust of about 10 to 40% when viewed from above;
Δ: Dust generation of about 40 to 70% when viewed from above (observation of the bottom surface is quite difficult);
X: Red rust floats almost throughout the liquid (observation of the bottom and sides is quite difficult), or peeling of the inner surface resin and blistering are observed from the cut part and others.

(Aperture condition)
Blank 100mm diameter,
Punch 50mm diameter -5R,
Dice 52.5 diameter-5R,
Aperture height 25mm,
Lubricant used, alkali degreasing after drawing.

Corrosion resistance 1
The back surface and the end surface were masked with a polyester tape, subjected to a salt spray test (JIS-Z-2371), and judged by the white rust area ratio after 240 hours (up to ◯ passed).

◎: White rust area ratio less than 5%;
○: White rust area ratio 5% or more and less than 10%;
○: White rust area ratio of 10% or more and less than 25%;
Δ: White rust area ratio of 25% or more and less than 50%;
X: White rust area ratio of 50% or more.

Corrosion resistance 2
After stretching to 140% with a universal tensile tester, the back and end surfaces were masked with polyester tape, and a salt spray test (JIS-Z-2371) was performed. The occurrence of red rust during the course of the course up to 240 hours was confirmed and judged (up to ○ passed).

A: No red rust occurs up to 240 hours;
○: No red rust generated until 120 hours, slightly red rust generated after 240 hours;
Δ: Slight red rust occurred in 120 hours;
X: Red rust is often generated in 120 hours.

The alkali-resistant back and end surfaces were masked with a polyester tape, immersed in an alkaline degreasing agent CL-N364S (20 g / L) manufactured by Nippon Parkerizing Co., Ltd. for 120 seconds, and washed with tap water. Subsequently, a salt spray test (JIS-Z-2371) was performed. Judgment was made based on the white rust area ratio after 240 hours (passed up to ○).

◎: White rust area ratio less than 5%;
○: White rust area ratio 5% or more and less than 10%;
○: White rust area ratio of 10% or more and less than 25%;
Δ: White rust area ratio of 25% or more and less than 50%;
X: White rust area ratio of 50% or more.

Adhesive (# 2403 Asahi rubber) was applied to two samples cut to a size of 25 mm × 200 mm with a bar coater, and a 0.18 mm spacer was sandwiched between both ends on the 200 mm side of the sample. Was adjusted to 180 μm. After leaving still for 30 minutes, it heated at 180 degreeC for 30 minutes, the adhesive agent was hardened, and also naturally cooled for 24 hours. The obtained adhesion test piece was subjected to a T peel peel test at a speed of 200 mm / min by the universal tensile test. Judgment was made based on the peel strength and peel appearance at that time (up to ◯ passed). The unit of peel strength is kgf / 25 mm.

A: Cohesive fracture area ratio of adhesive layer 100%, peel strength 17 or more;
○: Cohesive fracture area ratio of adhesive layer 100%, peel strength 16 or more, less than 7;
Δ: Cohesive failure rate of adhesive layer 50% or more, less than 100%, peel strength 13 or more, less than 6;
X: The cohesive failure rate of the adhesive layer is less than 50%, and the peel strength is less than 13.

After alkali degreasing the surface of the post-coating sample under the above conditions, Nippon Paint Odelac 9200TS Black was applied on one side as an outer coating to a thickness of about 20 μm. Then, after being immersed in warm water of 40 ° C. for 10 days, a crosscut was immediately put on the painted surface, and further, 7 mm was overhanged with Eriksen, and the tape peeling state of the overhanging portion was investigated (up to ○ passed).

○: No peeling;
Δ: Peeling at fine blister part;
X: Exfoliated greatly.

Soldering / Brazing Properties Solderability and brazing properties were investigated using Sn-Ag alloy made of tartin and brass as solder and brazing material, respectively. The fluxes were tartin L305 (chlorine) and boric acid, respectively. Evaluation is carried out by placing 0.5 g of solder or brazing material and 0.5 cc of flux on the outer surface of the sample, heating to 350 ° C. for Sn—Ag alloy solder, and 800 ° C. for brass brazing material, and spreading after 2 minutes. The area was evaluated (passed up to ○).

○: Solder and solder wetted areas are both 100 mm ² or more;
X: The wetted area of at least one of the solder and the solder is less than 100 mm ² or does not wet.
After two samples of resistance weldability were stacked, spot welding was performed under the conditions of pressure 300 kgf, energization 12 cycles, and current 8 kA, and the resistance between the electrodes in the first cycle was measured and determined as follows (○ Until pass).

A: Interelectrode resistance is 300 μΩ or less;
○: Interelectrode resistance is 300 μΩ or more, or slight dust is generated;
△: Generation of considerably large dust;
X: Not energized (not weldable).

After the moldable sample was drawn under the same conditions as the gasoline-resistant drawing process, the state of peeling with the adhesive tape on the outer side wall of the drawing was judged visually (up to ○ passed).

A: No peeling;
○: The tape is slightly glittering;
Δ: Peeling is clearly observed on the tape;
X: Peeling is recognized over almost the entire surface.

  As shown in Table 2, in Examples 1 to 17 in which a film was formed using an aqueous surface treating agent according to the present invention, when a test was performed by putting gasoline imitating deteriorated gasoline in a container degreased after alkali molding. It has excellent gasoline resistance, and even with alkaline degreasing, it has sufficient gasoline resistance to withstand deteriorated gasoline.

Moreover, the corrosion resistance after alkali degreasing (alkali resistance) was as good as the corrosion resistance before degreasing (corrosion resistance 1), and the corrosion resistance after processing (corrosion resistance 2) was also good.
On the other hand, Comparative Examples 1 to 5 do not contain any of components (A) to (E), and Comparative Examples 7 and 8 have a ratio of components (A) and (B) within the scope of the present invention. All of them were extremely poor in gasoline resistance and other performances. Comparative Example 6 containing no wax (F) was slightly inferior in moldability.


(Example 2)
As the base steel plate, the Zn-13% Ni alloy-plated steel plate of Example 1 and the electrogalvanized steel plate were used, and a surface treatment agent (treatment agent 1 in Table 1) was applied to the same conditions as in Example 1. A surface-treated plated steel sheet for a test was obtained.
Various performances of the obtained surface-treated plated steel sheet were evaluated by the same test methods as in Example 1. The test results are shown in Table 3.

As shown in Table 3, when the base steel plate was a zinc-nickel alloy plated steel plate, the performance was markedly better than when it was an electrogalvanized steel plate.

Claims (3)

Cationic phenolic resin comprising a cationic urethane resin (A) on at least one surface of a zinc-nickel alloy plated steel sheet and polymer molecules having an average degree of polymerization of 2 to 50 having a repeating unit represented by the following general formula (1) B), a coating formed by applying and drying an aqueous surface treatment agent containing phosphoric acid (C), titanium compound (D), vanadium compound (E), and lubricant (F) as components. The surface-treated plated steel sheet has a component ratio in the treatment agent of (A) 40 to 55 parts by mass, (B) 15 to 25 parts by mass, (C) 3 to 10 parts by mass in terms of P, (D The surface-treated plated steel sheet is 0.5 to 3 parts by mass in terms of Ti, 0.5 to 3 parts by mass in terms of (E) V, and 3 to 10 parts by mass of (F).

In the formula, Y ₁ and Y ₂ each independently represent a hydrogen atom or a Z group represented by the following formula (2) or formula (3).

R ₁ , R ₂ , R ₃ , R ₄ and R ₅ in formula (2) and formula (3) are each independently a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₁ -C ₁₀ hydroxyalkyl. The average substitution number of the Z group per benzene ring in the polymer molecule is 0.2 to 1.0. Deposition amount of the coating is in the range of 500 to 2000 / m ^2, the surface treatment plated steel sheet according to claim 1 or 2. A fuel container manufactured from the surface-treated plated steel sheet according to any one of claims 1 to 3 and having the coating on at least an inner surface.