JP5332836B2 - Plated steel sheet for cans - Google Patents

Description

  The present invention relates to a plated steel sheet for cans, which is used for beverage cans, food cans and the like, and has excellent secondary adhesion and corrosion resistance of organic coatings.

  Conventionally, surface-treated steel sheets that have been used as can materials are tin (Sn) plated steel sheets such as tinplate, LTS, and TNS, nickel plated steel sheets (TFS-NT), and electrolytic chromium plated steel sheets (TFS-CT). Is. Usually, the plating surface of these steel plates is subjected to chemical conversion treatment, thereby ensuring adhesion with paints and resin films.

  Most of the chemical conversion treatment of the surface-treated steel sheet for cans currently commercialized is immersion treatment or cathodic electrolysis treatment using an aqueous solution mainly composed of dichromate or chromic acid. As an exception, the negative anodization treatment in tin phosphate aqueous solution disclosed in Patent Documents 1 and 2 is known, but the application is limited to cans for powdered milk using the inner surface unpainted. Yes. The main reason why this negative anodization treatment is not used in beverage cans and food cans other than powdered milk cans is that the adhesion of organic coatings such as paints and resin films is insufficient.

  On the other hand, the chromium (III) oxide film obtained by dipping or cathodic electrolysis using an aqueous solution containing dichromate or chromic acid as a main component has a great effect of improving the adhesion of the organic film. Although various chemical conversion treatments have been studied, they have not yet been put into practical use. For example, Patent Document 3 discloses an electroplating tin for a DI can in which a phosphoric acid-based film is formed by immersion treatment. Patent Document 4 discloses a method of anodizing in a phytic acid or phytate solution.

  In recent years, many techniques for applying a film using a silane coupling agent on a tin plating layer have been disclosed. For example, Patent Document 5 discloses a steel sheet and a can provided with a silane coupling agent coating layer on a Sn layer or Fe-Sn alloy layer of a tin-plated steel sheet, and Patent Document 6 discloses a tin-plated layer. A tin-plated steel sheet having a chemical conversion film containing P and Sn as a lower layer and a silane coupling layer as an upper layer is disclosed. Further, Patent Documents 7 to 16 are disclosed as techniques similar to Patent Document 6.

JP 52-68832 A JP 52-75626 A JP 59-47396 A JP 52-92837 A JP 2002-285354 A JP 2001-316851 JP 2002-275643 A JP 2002-206191 A JP 2002-275657 A Japanese Patent Laid-Open No. 2002-339081 JP2003-3281 JP2003-175564A Japanese Patent Laid-Open No. 2003-183853 JP2003-239084 JP 2003-253466 A JP 2004-68063 A

However, it is difficult to say that any of the chemical conversion films described in the above-mentioned patent documents has performances such as secondary adhesion and corrosion resistance of an organic film necessary for use as a plated steel sheet for cans.
Then, this invention solves the problem of the said prior art, and aims at providing the plated steel plate for cans excellent in the secondary adhesiveness of an organic membrane | film | coat, and corrosion resistance.

  The inventors of the present invention have made extensive studies on the above-mentioned problems, and have found a film configuration of a tin-plated steel sheet that can obtain a very good secondary adhesion of an organic film, and have achieved the present invention.

(1) A plated steel sheet having metal tin continuously or intermittently on a steel sheet surface or an alloy layer containing iron and tin (Sn) formed on the steel sheet surface, and on the plated steel sheet, A 0.5 to 5.0 mg / m ² phosphate layer, and on the phosphate layer, a granular image projected on the steel plate surface has a diameter of 0.1 to 0.4 μm in terms of a circle. 2 to 15 mg / ^{m 2} oxides of Zr and / or hydroxide of Zr as Zr amount, as well as oxides of Si and / or Si to the hydroxide comprises 2 to 15 mg / ^{m 2} as the amount of Si, and the A plated steel sheet for cans having a silica-zirconia treated layer in which the total amount of Zr and Si is 5 to 30 mg / m ² ;

(2) The can-plated steel sheet according to (1) above, wherein the Si ratio Si / (Zr + Si) represented by the amount of metal in the silica-zirconia-treated layer is 0.2 to 0.8,

(3) The alloy layer containing iron and tin is composed of an Fe-Sn alloy layer having an Sn content of 0.1 to 1.8 g / m ² or an Fe-Ni-Sn alloy layer having an Ni content of ^{2 to} 100 mg / m ^2. The plated steel sheet for cans as described in (1) or (2) above,
It is.

  According to the present invention, it is possible to provide a plated steel sheet for cans having very good secondary adhesion and corrosion resistance of an organic film.

The present invention is described in detail below.
There is no particular limitation on the steel sheet used in the present invention. Component steel plates such as aluminum killed steel and low carbon steel that have been conventionally used for steel plates for cans can be used. Moreover, what is necessary is just to select the grade suitable for the intended purpose for the thickness and tempering degree of a steel plate.

The main structure of the present invention is a plated steel sheet having metal tin continuously or intermittently on the steel sheet surface or on an alloy layer containing iron and tin formed on the steel sheet surface, and the P amount on the plated steel sheet. 0.5 to 5.0 mg / m ² of the phosphate layer, and Zr oxide and / or Zr hydroxide on the phosphate layer as the Zr amount of ^{2 to} 15 mg / m ² , and Si oxide And / or a silica-zirconia treatment layer containing ^{2 to} 15 mg / m ² of Si hydroxide as a Si amount, and the total of the Zr amount and the Si amount being 5 to 30 mg / m ^2. It is a plated steel sheet for cans.

Metal tin on the steel sheet surface or on the alloy layer containing iron and tin can be deposited by electroplating from an acidic bath to which appropriate organic additives are added, so that even with a relatively small amount of adhesion, the surface of the steel sheet or iron and It is possible to continuously coat the alloy layer containing tin. Although the tin adhesion amount is not limited, the metal tin amount is preferably 0.4 g / m ² or more from the viewpoint of appearance and weldability. If the amount of metallic tin is less than 0.4 g / m ² , the exposed area of the steel plate surface or alloy layer surface becomes large, so that the tin-plated steel plate has a strong black appearance and it is difficult to ensure weldability. Assuming that the reflow treatment is performed, it is preferable that the total Sn amount represented by the total amount of metal tin and alloy tin is 0.5 to 15 g / m ² . Even if the amount of tin exceeding 15 g / m ² is deposited, it should be avoided because there is no significant improvement in performance and the economic disadvantage increases.

  By performing the reflow treatment under specific conditions, it is possible to make the metal tin intermittently distributed, and it may be selected when such a tin-plated steel sheet is used for a necessary application.

In the present invention, a phosphate layer having a P content of 0.5 to 5.0 mg / m ² on the metal tin and / or the alloy layer, and an oxide of Zr and / or Zr on the phosphate layer. the total of the hydroxide include ^{2~15mg / m 2 2~15mg / m 2} , as well as oxides of Si and / or Si to the hydroxide as Si amount of Zr weight and the Zr amount and the Si amount There silica is 5 to 30 mg / m ² - it is necessary to have a zirconia treated layer.

The phosphate layer having a P content of 0.5 to 5.0 mg / m ² plays a role of firmly adhering the silica-zirconia treatment layer, which is an upper layer, to the substrate. That is, even if Zr or Si oxides or hydroxides are directly attached to a tin-plated steel sheet, the adhesion between them is insufficient, and even if a paint or resin film is laminated on the surface, the adhesion is poor. It is easy to peel off at the tin-plated steel sheet-Zr compound interface and the tin-plated steel sheet-Si compound interface. Phosphate is suitable as an intermediate layer because it has high adhesion to Zr and Si oxides and hydroxides.

Phosphate mainly consists of iron phosphate and tin phosphate, and the total amount of deposited P can be measured from fluorescent X-ray intensity using a calibration curve prepared in advance. The total amount of phosphate needs to be 0.5 to 5.0 mg / m ² as P. If it is less than 0.5 mg / m ² , the area ratio of the tin layer, the tin alloy layer and the steel plate surface that are not covered with phosphate increases, so that the oxides and hydroxides of Zr and Si are easy to peel off. On the other hand, phosphates with an amount of P exceeding 5.0 mg / m ² are liable to cohesive failure, so that the adhesion of the organic film cannot be ensured.

The silica-zirconia-treated layer needs to have a Zr amount of ^{2 to} 15 mg / m ² , a Si amount of ^{2 to} 15 mg / m ² , and a total of both of 5 to 30 mg / m ² .

The shape of Zr oxide and hydroxide on the phosphate layer of tin-plated steel sheet is granular, and the particle diameter is 0.1 to 0.4 μm in terms of a circle with the same area as the image of the grain projected on the steel sheet surface. It is desirable that Since coatings and resin films are laminated in a low viscosity state, the so-called anchor effect can be obtained by hardening after flowing so as to enclose such granular Zr oxides or hydroxides, so that the adhesion of the organic film It is thought to contribute to sex. However, when the amount of Zr is less than 2 mg / m ² , Zr oxides and hydroxides do not have the above-mentioned shape, and it is difficult to obtain sufficient organic film adhesion. On the other hand, if the amount of Zr exceeds 15 mg / m ² , the area ratio of the oxides and hydroxides of Si described below is not sufficiently ensured, so that it is difficult to ensure corrosion resistance.

The shape of the Si oxide and hydroxide on the phosphate layer of the tin-plated steel sheet is layered, and is uniformly distributed in a portion where there is no or little Zr oxide or hydroxide. Si oxides and hydroxides are bonded to the organic film having a polar group, possibly by hydrogen bonding, and prevent penetration of the aqueous solution into the interface, thereby contributing to the improvement of secondary adhesion. If the amount of Si is less than 2 mg / m ^2, it is insufficient to cover the phosphate layer, and the above effect is difficult to obtain. On the other hand, if it exceeds 15 mg / m ² , it tends to cause cohesive failure, rather the adhesion of the organic film is lowered.

The sum of the Zr amount and the Si amount needs to be 5 to 30 mg / m ² . If it is less than 5 mg / m ² , the above characteristics may be insufficient. On the other hand, if it exceeds 30 mg / m ² , the above properties are saturated or deteriorated and it is not economical.

  The Si ratio Si / (Zr + Si) expressed by the amount of metal in the silica-zirconia-treated layer is preferably 0.2 to 0.8. If the ratio of Si in the above adhesion amount is within this range, the area ratio of Zr oxide and / or Zr hydroxide, and Si oxide and / or Si hydroxide is optimal. The properties are exhibited well and extremely good organic film adhesion is obtained.

When having an alloy layer containing iron and tin on the steel sheet surface, from an Fe-Sn alloy layer of 0.1 to 1.8 g / m ² as the Sn amount, or from an Fe-Ni-Sn alloy layer of ^{2 to} 100 mg / m ² as the Ni amount Preferably it consists of: In the case of the Fe—Sn alloy, the composition is FeSn _2, and this amount is preferably 0.1 to 1.8 g / m ² as the Sn amount. In a tin-plated steel sheet that undergoes a tin heating and melting step (reflow treatment) after tin plating, a tin alloy layer of 0.1 g / m ² is inevitably formed, whereas it exceeds 1.8 g / m ² Then, it is not preferable because minute cracks are likely to be generated in processing steps such as bending and curling, and there is a risk of starting corrosion. In the case of the Fe—Ni—Sn alloy, this amount is preferably ² to 100 mg / m ² as the Ni amount. Ni is added to prevent excessive formation of the alloy layer, but if Ni is less than 2 mg / m ² , the effect is insufficient. On the other hand, if it exceeds 100 mg / m ² , the amount of Ni-Sn alloy increases, and the iron ratio in the alloy layer decreases, resulting in a decrease in the amount of iron phosphate produced and the primary and secondary organic coatings. It is not preferable because it is difficult to ensure adhesion.

  Although it does not limit about the manufacturing method of the plated steel plate for cans which is this invention, it can manufacture by the following method.

  The method of plating pretreatment of the steel sheet and the tin plating bath to be used are not particularly limited in the present invention, but after performing electrolytic alkaline degreasing and dilute sulfuric acid pickling as pretreatment, a phenolsulfonic acid bath containing an organic gloss additive, When tin is electroplated in an acidic tin plating bath such as a sulfuric acid bath, good tin plating is obtained. Note that Fe—Ni alloy plating may be performed before tin plating. Or after giving nickel plating, it may heat and diffuse nickel to a steel plate surface layer, and may form an Fe-Ni alloy layer.

  The steel plate after tin plating may be subjected to a reflow treatment after being dipped in a bath containing water or a solution in which a tin plating solution is diluted and dried. The reflow treatment is a step of heating the tin-plated steel sheet to 232 ° C. or higher, which is the melting point of tin, but if it exceeds 300 ° C., Fe—Sn alloying is excessively promoted, which is not preferable. As a heating means, electric resistance heating, induction heating, or a combination thereof may be used. It is necessary to prevent excessive formation of the Fe—Sn alloy layer or the Fe—Ni—Sn alloy layer or the surface tin oxide layer by quenching immediately after the reflow treatment. The quenching process is performed by immersing a tin-plated steel sheet in which tin is melted in water. When the strip is continuously reflowed and quenched, the water in the quench bath is preferably about 80 ° C.

Next, chemical conversion treatment may be performed by the method described below.
First, cathodic electrolysis is performed in a phosphoric acid aqueous solution having a liquid temperature of 30 to 55 ° C. and a pH of 1.5 to 3.5 at a cathode current density of ^{2 to} 30 A / dm ² for 0.1 to ² seconds. The chemical species of phosphoric acid in a phosphoric acid aqueous solution having a pH of 1.5 to 3.5 are mainly phosphoric acid and dihydrogen phosphate ion, and a trace amount of hydrogen phosphate ion is also present. As the cation component other than hydrogen ions in the phosphoric acid aqueous solution, one or more selected from sodium ions, potassium ions, calcium ions, magnesium ions, and ammonium ions can be used without any problem.

Cathodic electrolysis in an aqueous phosphate solution is a step of reducing tin oxide and iron oxide produced on the surface of a tin-plated steel sheet mainly by reflow treatment to a metal and forming a phosphate layer. When a large amount of tin oxide remains, formation of a phosphate film is hindered. When the cathode current density is less than 2 A / dm ² , tin oxide or iron oxide generated by the reflow treatment may not be sufficiently reduced. On the other hand, even if the cathode current density is made higher than 30 A / dm ² , the amount of hydrogen gas generated on the cathode surface is increased, which is not efficient. If the electrolysis time is shorter than 0.1 second, tin oxide or iron oxide may not be sufficiently reduced. On the other hand, tin oxide and iron oxide are sufficiently reduced within 2 seconds of electrolysis, so even if the length is longer than this, productivity is reduced and no improvement in performance is observed.

Subsequent to cathodic electrolysis in an aqueous phosphate solution, anodic electrolysis is preferably performed under suitable conditions, since the formation of a phosphate film proceeds further. In the anodic electrolytic treatment, tin and iron on the steel sheet surface are slowly oxidized and dissolved, and iron phosphate and tin phosphate are formed by combining with phosphate ions in the treatment solution. The anode current density of the anodic electrolysis is suitably 0.2 to 5 A / dm ² , and the electrolysis time is suitably 0.1 to ² seconds. If it is less than 0.2 A / dm ² or less than 0.1 second, the effect of promoting the formation of phosphate is insufficient, and there is no improvement effect compared to the case where only cathodic electrolysis is performed. On the other hand, if it exceeds 5 A / dm ^2, the dissolution rate of tin and iron is too fast, and the resulting phosphate layer becomes sparse and brittle. When the electrolysis time exceeds 2 seconds, the productivity is lowered, and the phosphate layer becomes thick, resulting in a brittle film.

After the chemical conversion treatment, the steel plate is further processed with 1-10 g / L of zirconium (IV), 1-10 g / L of silicon (IV), 5-50 g / L of fluoride ions, 1-5 g / L of nitric acid. By performing cathodic electrolysis in an aqueous solution containing one or two ions, pH 2.5-6, bath temperature 10-55 ° C, current density 1-15 A / dm ² , electrolysis time 0.1-2 seconds Thus, a tin-plated steel sheet of the present invention showing good organic film adhesion can be obtained with a surface in which an appropriate amount of granular Zr oxide and / or hydroxide and layered Si oxide and / or hydroxide are distributed. It is done.

  Preferred zirconium (IV) compounds to be added to the treatment bath include ammonium zirconium fluoride and zirconium nitrate oxide, and preferred silicon (IV) compounds include ammonium fluorofluoride.

Hereinafter, the present invention will be described in more detail by way of examples.
A steel strip having a thickness of 0.18 mm and a tempering degree of T-5CA obtained by continuous annealing and then temper rolling of a low carbon cold rolled steel strip was used. As a pretreatment for plating, electrolytic degreasing was carried out in a 10 mass% sodium hydroxide solution, followed by pickling with 5 mass% dilute sulfuric acid.

  Some steel strips were plated with Fe-Ni alloy or Ni. The steel strip subjected to Ni plating was then annealed to diffuse Ni and form a Fe—Ni alloy layer.

Subsequently, electrotin plating was performed using a ferrostan bath. Cathodic electrolysis was performed at a cathode current density of 20 A / dm ² in a plating solution at 43 ° C. containing 20 g / L of tin ions, 75 g / L of phenolsulfonic acid ions, and 5 g / L of surfactant. As the anode, platinum-plated titanium was used. The total amount of tin plating was 1.5 g / dm ² .

  Some tin-plated steel strips are immersed in a 10-fold diluted tin plating solution, drained with a rubber roll, dried with cold air, heated to 250 ° C for 5 seconds by energization heating, and tin is Reflowed and immediately quenched with 80 ° C. water.

Subsequently, the tin-plated steel sheet was subjected to chemical conversion treatment as follows.
Cathodic electrolysis was performed in a treatment solution containing 35 g / L of total phosphoric acid in terms of phosphoric acid and 4 g / L of sodium ion at a solution temperature of 40 ° C. In some examples, anodic electrolysis was performed in an aqueous solution of the same composition.

Next, 1 to 10 g / L zirconium (IV), 1 to 10 g / L silicon (IV) and 20 g / L fluoride ions, 2.5 g / L nitrate ions, pH 4.0, bath temperature 40 Cathodic electrolysis was performed in an aqueous solution at 0 ° C. with a current density of 10 A / dm ² and an electrolysis time of 0.4 seconds. After the electrolytic treatment, the solution was squeezed with a rubber roll, and then quickly washed with water and dried.

  The adhesion amount of P, Zr, and Ni was calculated from the fluorescent X-ray intensity using a calibration curve prepared in advance. The amount of Sn deposited was determined by an electrolytic stripping method using a tin-plated steel sheet as an anode in 1 mol / L dilute hydrochloric acid. In addition, the presence of P as tin phosphate and iron phosphate means that the ratio of Sn, Fe, P, O in a small region by AES (Auger electron spectroscopy), Sn by XPS (X-ray photoelectron spectroscopy), This was confirmed by analysis of the bonding state of Fe, P, and O.

About the said processing material, the evaluation test was implemented about each item of (A)-(C) shown below.
(A) Paint primary adhesion

The evaluation material was coated with 60 mg / dm ^{2 of} epoxy / phenolic paint and baked at 210 ° C. for 10 minutes. Further, the baking was performed at 190 ° C. for 15 minutes and at 230 ° C. for 90 seconds. A sample having a size of 5 mm × 100 mm was cut out from the coated plate. Two samples of the same level were coated with the coated surfaces facing each other, and a film-like nylon adhesive having a thickness of 100 μm was sandwiched between them. This was left pre-heated with a hot press at 200 ° C. for 60 seconds, and then pressure-bonded at 2.9 × 10 ⁵ Pa for 50 seconds at 200 ° C. to obtain a tensile test piece. Each of the grip portions was bent at a 90 ° angle to form a T shape, and was pulled with a chuck of a tensile tester, and the peel strength was measured to evaluate the primary adhesion of the paint. The measured strength per test piece width of 5 mm was evaluated as ◎ for 70 N or more, ◯ for 55 N or more and less than 70 N, Δ for 40 N or more and less than 55 N, and × for less than 40 N.
(B) Paint secondary adhesion

The evaluation material was coated, baked, and pressure-bonded with a nylon adhesive sandwiched in the same manner as in (A) to prepare a test piece. This was retorted at 125 ° C for 30 minutes. Immediately after that, the gripping portions were bent at 90 ° angles to form a T-shape. The next adhesion was evaluated. The measured strength per 5 mm of the test piece width was 50N or more, 40, 40N or more and less than 50N, ○, 30N or more and less than 40N, or less than 30N, ×.
(C) Corrosion resistance

In order to evaluate the corrosion resistance in an acidic solution containing chloride ions on the surface corresponding to the inner surface of the can of the evaluation material, a UCC (Under Cutting Corrosion) test was performed. An epoxy / phenolic paint was applied at 50 mg / dm ^{2 and} baked at 205 ° C. for 10 minutes. Further, it was baked for 10 minutes at 180 ° C. A sample having a size of 50 mm × 50 mm was cut out from the coated plate. Cross-cut the coating film until it reaches the ground iron with a cutter, seal the end and back with paint, and then in a test solution at 1.5C consisting of 1.5% citric acid and 1.5% sodium chloride for 96 hours in the open air Soaked. After washing and drying, after attaching cello tape (registered trademark) (Nichiban No. 405) to the scratch part and the flat part, it peels off vigorously, and the corrosion situation near the cross cut part, the pitting corrosion of the cross cut part and the flat part The coating film peeling state of the part was observed to evaluate the corrosion resistance. ◎ (excellent) where no peeling or corrosion due to tape is observed, ○ (good) where one or both of tape peeling less than 0.2 mm from scratch or slight corrosion not visually recognized △ (slightly defective) when one or both of tape peeling of 0.2 mm or more and 0.4 mm or less or small corrosion visually recognized from the scratch part was observed, and × (bad) when tape peeling exceeding 0.4 mm occurred ).

  Based on the above performance evaluation results, the overall evaluation was classified into four stages: ◎ (very good), ○ (good), △ (slightly bad), and × (bad), and ◎ and ○ were regarded as acceptable levels.

  The test conditions not described above are shown in Tables 1 and 2, and the evaluation results are shown in Tables 3 and 4.

本発明の実施例1〜35は、全ての評価項目及び総合評価で、◎又は○であり、求められる性能を満足した。中でもＳｉ／（Ｓｉ＋Ｚｒ）が０．２〜０．８の範囲の水準は良好な塗料密着性を示しており、好適である事が判る。

Examples 1-35 of this invention were (double-circle) or (circle) in all the evaluation items and comprehensive evaluation, and satisfy | filled the calculated | required performance. Above all, the level of Si / (Si + Zr) in the range of 0.2 to 0.8 indicates good paint adhesion, which proves preferable.

  Comparative Example 1 is an example in which both silicon oxide and zirconium oxide have a small amount of adhesion. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 2 is an example in which the amount of silicon oxide attached is small. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 3 is an example in which the total amount of silicon oxide and zirconium oxide is small. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 4 is an example in which the adhesion amount of zirconium oxide and the total amount of silicon oxide and zirconium oxide are small. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Examples 5 and 6 are examples in which the adhesion amount of zirconium oxide is small. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 7 is an example in which the amount of zirconium oxide attached is large. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 8 is an example in which the amount of zirconium oxide attached is large. Sufficient secondary paint adhesion and corrosion resistance were not obtained. Comparative Example 9 is an example in which the adhesion amount of zirconium oxide and the total amount of silicon oxide and zirconium oxide are large. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Examples 10 and 11 are examples in which the amount of silicon oxide attached is large. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 12 is an example in which the amount of silicon oxide attached and the total amount of silicon oxide and zirconium oxide are large. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 13 is an example in which the amount of phosphate adhered is small. Sufficient paint adhesion and corrosion resistance were not obtained. Comparative Example 14 is an example in which the amount of phosphate adhered is large. Sufficient paint adhesion and corrosion resistance were not obtained.

Claims (3)

A plated steel sheet having a metal tin continuously or intermittently on a steel sheet surface or an alloy layer containing iron and tin (Sn) formed on the steel sheet surface, the P amount being 0.5 on the plated steel sheet Oxidation of granular Zr having a diameter of 0.1 to 0.4 μm in terms of a circle on the surface of a steel sheet on a phosphate layer of ˜5.0 mg / m ² and further on the phosphate layer things and / or hydroxide of Zr include ^{2~15mg / m 2 2~15mg / m 2} , as well as oxides of Si and / or Si to the hydroxide as Si amount of Zr weight and the Zr amount and A plated steel sheet for cans comprising a silica-zirconia-treated layer having a total amount of Si of 5 to 30 mg / m ² .   2. The plated steel sheet for cans according to claim 1, wherein the Si ratio Si / (Zr + Si) expressed by the amount of metal in the silica-zirconia-treated layer is 0.2 to 0.8. The alloy layer containing iron and tin is composed of a Fe—Sn alloy layer having a Sn content of 0.1 to 1.8 g / m ² or a Fe—Ni—Sn alloy layer having a Ni content of ^{2 to} 100 mg / m ^2. The plated steel sheet for cans according to claim 1 or 2, characterized in that