JP3851482B2 - Galvanized steel sheet with excellent white rust resistance and coating adhesion - Google Patents

Description

【００３５】
Ｎｏ．１〜３７は、処理層として本発明に係る混合物皮膜が形成されている本発明例であり、従来例Ｎｏ．３８，３９に示すクロメ−ト処理材と同等以上の優れた耐白錆性と塗膜密着性を発揮した。これに対して、処理層が、本発明に係る成分組成分布ではない比較例Ｎｏ．４０〜４７の場合には、耐食性及び／または塗膜密着性が十分ではなかった。また、希土類元素および／またはIVａ属元素の酸化物及び水酸化物の金属換算付着量が適正でない比較例Ｎｏ．４８〜５１の場合でも、耐食性及び／または塗膜密着性が十分ではなかった。
【００３６】
実施例２
実施例１と同様の方法にて、希土類元素またはIVａ属元素の化合物を付与した亜鉛めっき鋼板を作製した。得られた該めっき鋼板に、有機物または無機物を主体とする皮膜を絞りロ−ル法にて、乾燥後の皮膜厚さが有機物を主体とする場合にはO．５μｍ、無機物を主体とする場合には０．１μｍになるように塗布した。有機物を主体とする皮膜については、ポリエステル系樹脂を主体としコロイダルシリカおよびワックスを添加したもの、無機物を主体とする皮膜については、リチウムシリケ−トおよびコロイダルシリカを主体として、ポリエステル樹脂、ワックスおよびシランカップリング剤を添加したものを用いた。
【００３７】
得られた有機または無機皮膜被覆めっき鋼板について、実施例１と同様の方法にて、耐白錆性および塗膜密着性を調査した。ただし、耐白錆性については、塩水噴霧試験（ＳＳＴ）１２０時間後の白錆発生面積率を、実施例１と同様の評価基準で調査した。得られた結果を表２にまとめて示す。
【００３８】
【表２】

【００３９】
Ｎｏ．１〜１７は、処理層として本発明に係る混合物皮膜が形成されている本発明例であり、従来例Ｎｏ．２６，２７に示すクロメ−ト処理材と同等以上の優れた耐白錆性と塗膜密着性を発揮した。これに対して、処理層が、本発明に係る混合物皮膜でない比較例Ｎｏ．１８〜２３の場合には、耐食性及び／または塗膜密着性が十分ではなかった。また、希土類元素および／またはIVａ属元素の酸化物及び水酸化物の金属換算付着量が適正でない比較例Ｎｏ．２４〜２５の場合でも、耐食性及び／または塗膜密着性が十分ではなかった。
【００４０】
【発明の効果】
本発明は以上の様に構成されているので、環境に有害なクロメ−ト処理を全く用いることなく、優れた耐白錆性と塗膜密着性を発揮する亜鉛系めっき鋼板が提供できることとなった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zinc-based plated steel sheet that is excellent in white rust resistance and coating film adhesion, and more particularly to a zinc-based plated steel sheet having a coating layer that does not contain any harmful element hexavalent chromium.
[0002]
[Prior art]
Zn-plated steel sheet has a sacrificial anti-corrosion effect on the steel sheet, and exhibits excellent corrosion resistance (red rust resistance) due to the excellent protective action of the corrosion product of Zn. It is used in a wide range of fields such as home appliances. Conventionally, as a characteristic required for a Zn-plated steel sheet, the corrosion resistance (that is, red rust resistance) of the steel sheet itself has been regarded as important from the viewpoint of preventing the strength of the steel sheet structure from being deteriorated by corrosion. . Therefore, for example, automobile steel sheets and the like are subjected to coating after being subjected to chemical conversion treatment represented by chromate treatment.
[0003]
In recent years, Zn-plated steel sheets are frequently used for chassis and case parts of home appliances and OA equipment, and chrome treatment is performed on the Zn-plated layer, and about 0.5 to 1 μm. After applying a very thin clear film, the proportion used without painting increased greatly. As a result, the appearance of the Zn-plated steel sheet itself has become an important characteristic, and white rust, which is the rust of Zn itself, has been regarded as a problem. The chromate-treated film was developed for the purpose of preventing white rust of Zn, and the chromate treatment exhibits a white rust suppressing effect due to the self-repairing action of hexavalent chromium. However, it has been pointed out that the chromate treatment product has a problem of environmental pollution due to elution of hexavalent chromium, and in the production process, the harmful chromate ion contained in the treatment liquid is made harmless. Wastewater treatment leads to increased costs, and measures against adverse effects on the human body in the work environment are also necessary. Therefore, research and development of a non-chromate film, which is a rust preventive film that is not subjected to chromate treatment, has been actively conducted. As a rust preventive film containing no chromium at all, for example, Japanese Patent Application Laid-Open Nos. 10-337530, 11-61429, 11-61431, and 11-61432 describe rare earth elements or A corrosion-resistant coating layer composed mainly of a compound of group IVa element is disclosed.
[0004]
However, the chromate film has an important role not only in improving corrosion resistance (white rust resistance) but also in improving adhesion with various clear films including the upper clear film. A non-chromate film that sufficiently satisfies both the characteristics of rust and coating film adhesion has not been obtained yet.
[0005]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above circumstances, and is intended to provide a non-chromate-treated steel sheet excellent in white rust resistance and having excellent coating film adhesion. It is.
[0006]
[Means for Solving the Problems]
The zinc-based plated steel sheet of the present invention having excellent white rust resistance and coating film adhesion that solves the above-mentioned problems is that a rare earth element and / or a group IVa element compound film of two or more elements is formed on the plating surface. A zinc-based plated steel sheet, wherein the compound film is mainly composed of one or more oxides and hydroxides of rare earth elements and / or group IVa elements, and in the vicinity of the interface with the plating layer in an oxide as a main component, near the surface all SANYO mainly composed of hydroxides, the molar number of oxygen atoms constituting the oxide of a rare earth element and / or IV a group element in the compound layer a, the rare earth when the molar number of oxygen atoms constituting the hydroxides of the elements and / or IV a group element is B, the value of a / B is O. The gist is that it is 2 or more and 10 or less, and the composition in the depth direction of the compound film is desirably a gradient mixed composition of the oxide and the hydroxide.
[0007]
The coating weight of the mixture film consisting mainly of one or more oxides of rare earth elements and / or IVa group element and hydroxides may be 5～1500Mg / m ² in terms of metal Desirably, La, Ce, and Y are preferable as the rare earth element, and Zr and Ti are preferable as the IVa group element.
[0008]
Furthermore, a composite coated zinc-based plated steel sheet that exhibits more excellent characteristics if an organic or / and inorganic film is formed in a thickness of 0.01 to 20 μm on the upper layer of the compound film in the zinc-based plated steel sheet. Can be obtained.
[0009]
In the present invention, the value of A / B is an average value of five points in the film thickness direction. When the film thickness is t, the depth is 0, t / 4, t / 2 from the surface side. It is an average value of values obtained by measuring A / B at a total of 5 points in the vicinity of 3t / 4 and t.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The inventors of the present invention relate to the galvanized steel sheet on which a compound film of rare earth elements and / or group IVa elements is formed, the types and combinations of the above compounds, their distribution state, corrosion resistance (particularly white rust resistance), and coating film. We have earnestly studied the relationship of adhesion. As a result, in order to improve white rust resistance and coating film adhesion, it is extremely effective to use oxides and hydroxides of rare earth elements and / or group IVa elements together, and the mixing and distribution of both. Depending on the difference in the state, it can be found that there is a large variation in white rust resistance and coating adhesion, and if the distribution state of the above oxides and hydroxides is optimally controlled, very good white rust resistance The inventors have found that both the coating film adhesion and the coating film adhesion can be obtained stably, and have arrived at the present invention.
[0011]
Specifically, in a mixed film of rare earth elements and / or group IVa element compounds, an oxide of the element is formed in the vicinity of the interface between the plating layer and the mixed film (hereinafter sometimes simply referred to as “near the interface”). Excellent white rust resistance and coating adhesion by using a film structure mainly composed of hydroxide near the surface of the mixture film (hereinafter sometimes simply referred to as “near the surface”). Can be obtained. In particular, a film having a gradient composition from the plating layer side to the surface is desirable. In this case, the composition change from the plating layer side to the surface of the oxide and hydroxide of the present invention may be continuous or may be a discontinuous change having a multilayer structure. In the present invention, the vicinity of the interface refers to a region closer to the plating layer side than about 3t / 4 of the thickness t of the mixture film, and the vicinity of the surface is the same from about t / 4 of the thickness to the surface. Let's say the near area.
[0012]
The reason why the mixed film of the rare earth element and / or IVa group element compound has the component composition distribution according to the present invention is excellent in white rust resistance and coating film adhesion is not clear, but is presumed as follows. The That is, oxides or hydroxides of rare earth elements and Group IVa elements have extremely low solubility in water in the neutral region (about pH 6-7), and once formed on the surface of the plating layer, wet environments such as rainwater and condensation Under the elution of the mixture film is slight, it is possible to maintain the mixture film for a long time. In addition to the above characteristics, oxides form a dense film and are extremely stable even in an acidic region where the pH is 4 or less. Therefore, the oxide rain environment and chloride ions containing SOx and NOx It is presumed that the plating layer can be firmly protected without being eluted even in a severe corrosive environment. On the other hand, in addition to the above-mentioned properties, hydroxides contain OH groups in the molecule, so it is inferred that the adhesion with a coating mainly composed of organic matter or containing organic matter is very good. The Therefore, by providing rare earth elements and / or IVa group hydroxides as the main component in the vicinity of the surface, while ensuring excellent coating film adhesion and white rust resistance, the main component is the oxide in the vicinity of the interface. Therefore, in the present invention, it is considered that a further effect of improving white rust resistance was obtained.
[0013]
Moreover, in the film according to the present invention, it is desirable to control the mixing ratio of oxide and hydroxide as follows. That is, when the number of moles of oxygen atoms constituting the oxide of the rare earth element and / or group IVa element is A and the number of moles of oxygen atoms constituting the hydroxide is B, the value of A / B is O.O. It is recommended to control to 2 or more and 10 or less. In calculating the value of A / B, it is difficult to measure the entire film, and therefore, an average value is obtained by taking five points in the film thickness direction. Specifically, when the film thickness is t, A / B is measured at a total of 5 points in the vicinity of depth 0, t / 4, t / 2, 3t / 4, and t from the surface side, and the average of them is measured. A value (hereinafter referred to as “average A / B”) is calculated. The average A / B is preferably 0.2 or more and 10 or less. It is more preferable if it is 3 or more and 8 or less. Average A / B is O.D. If it is less than 2, the white rust resistance is inferior, and if it exceeds 10, the coating film adhesion is insufficient, and the entire oxide film is so brittle that the film itself becomes brittle and the film falls off during processing. Arise.
[0014]
Note that the method for measuring the number of moles of oxygen atoms constituting the oxide and hydroxide is not particularly limited as long as the ratio (A / B) can be measured. Measurement was performed using an analytical method (ESCA). For example, in the case of La, an oxygen 1s narrow region photoelectron spectrum is measured, and a peak appearing in the vicinity of a binding energy of 532 eV is caused by hydroxide, and a peak appearing in the vicinity of 528.5 eV is oxidized. As a result of the product, the molar ratio (A / B) was determined from each peak area ratio. The A / B value at each position in the film thickness direction was sputtered with Ar ions, and the same measurement was repeated.
[0015]
All rare earth elements and Group IVa elements are applicable to the mixture film in the present invention, and the valence of the metal is not particularly limited. For example, lanthanoid elements such as La, Ce, Pr, Nd, and Sm, Y, and Ti, Zr, and Hf are applicable. La, Ce, Y, Zr, and Ti are preferable in consideration of ease of handling and cost. In addition, these rare earth elements and / or IVa group elements may be used alone or in combination of two or more.
[0016]
The adhesion amount of the rare earth element and / or group IVa element compound applied to the plating surface may be 5 to 1500 mg / m ^{2 in} terms of metal, and more preferably 10 to 1000 mg / m ² . When the amount of metal equivalent adhesion is less than 5 mg / m ² , sufficient white rust resistance and coating film adhesion cannot be obtained. On the other hand, even when applied in excess of 1500 mg / m ² , white rust resistance is not obtained. Since the improvement effect is saturated, it is not economically preferable, and there is a problem that the film becomes powdery and easily peels and drops.
[0017]
The material to be treated for treating the mixed film of the rare earth element and / or group IVa element compound of the present invention is not limited as long as it is a plated steel sheet mainly composed of zinc, for example, Zn plating containing inevitable impurities. Including steel sheets, Zn-Mg, Zn-Mg-C, Zn-Ni, Zn-Co, Zn-Fe, Zn-Cr, Zn-Co-Mo, Zn-A1, Zn-A1-Si alloy plated steel sheets, etc. Applicable. Further, the plating production method is not limited at all, and a known electroplating method, hot dipping method, and vapor deposition plating method can be used.
[0018]
The method for providing the mixed film of the rare earth element and / or IVa group element compound of the present invention is not particularly limited as long as the film structure of the present invention can be achieved. For example, a treatment liquid containing ions or oxides / hydroxides of rare earth elements and / or Group IVa elements as appropriate is applied to the surface of a zinc-based plated steel sheet by spraying, brushing, bar coating, roll coating. What is necessary is just to dry, after apply | coating by methods, such as apply | coating by immersion etc. or being immersed. Further, it is also possible to apply a method of performing electrolytic treatment using a zinc-based plated steel sheet as a cathode in a treatment liquid containing ions of rare earth elements and / or group IVa elements and then drying.
[0019]
In order to obtain the gradient composition film of the oxide and hydroxide of the present invention, it is easily possible by appropriately controlling the drying temperature and the drying time, for example. According to the experiments by the present inventors, the gradient composition film of the present invention can be obtained when the plate temperature during drying is about room temperature to about 200 ° C. and the drying time is about 10 to 120 seconds. Further, in the electrolytic treatment method, the film structure can be similarly controlled by appropriately controlling the treatment liquid composition and electrolysis conditions. According to experiments conducted by the present inventors using an electrolytic treatment method, the metal ion concentration of the present invention in the treatment liquid is 0.001 to 1 mol / L, the pH of the treatment liquid is 1.0 to 5.0, and the treatment liquid. Temperature is 20 to 70 ° C., current density during electrolysis is 1 to 100 A / dm ² , and energization amount is O.D. O1-2C / cm ² , the relative flow rate of the treatment liquid and the material to be treated is 0-5. In the range of Om / sec, it was possible to obtain the gradient composition film of the present invention. Furthermore, in order to obtain the gradient composition film of the oxide and hydroxide of the present invention, it is possible to carry out a plurality of treatments by appropriately changing the drying conditions or the composition of the treatment liquid.
[0020]
For the purpose of further improving white rust resistance, an organic and / or inorganic coating is added to the outermost surface of the galvanized steel sheet having the mixture coating of the rare earth element and / or group IVa element compound of the present invention described above. . You may form by thickness of 01-20 micrometers (preferably 0.05-10 micrometers). The thickness of the organic and / or inorganic film is O.D. If it is less than 01 μm, the effect of improving white rust resistance is not sufficient, and even if it exceeds 20 μm, the effect of improving white rust resistance is saturated, which is economically undesirable.
[0021]
When an organic resin is mainly used as a film formed on the outermost surface, an epoxy resin, a polyester resin, a polyurethane resin, an ethylene copolymer resin containing an ethylenically unsaturated carboxylic acid as a polymerization component, or a polyvinyl resin , Polyamide resins, fluororesins and other organic resin components may be used, or corrosion resistance, lubricity, scratch resistance, workability, weldability, electrodeposition coating adhesion, coating To improve the quality of film adhesion, etc., if necessary, apply a treatment solution containing various oxide particles such as silica, inorganic pigments such as various phosphates, and wax particles, organosilane compounds, naphthenates, etc.・ It only needs to be dried.
[0022]
In addition, when an inorganic substance is mainly used as a film formed on the outermost surface, a film mainly containing a silicate such as soda silicate, potassium silicate, lithium silicate or the like may be used. Various oxide particles such as colloidal silica and various kinds as necessary to improve quality such as film properties, corrosion resistance, lubricity, scratch resistance, workability, weldability, electrodeposition coating film adhesion, coating film adhesion, etc. A treatment solution containing an inorganic pigment such as phosphoric acid, wax particles, an organic silane compound, and the above-described organic resin may be applied and dried.
[0023]
The organic or inorganic coating can be used alone or in combination. The order of combination is not particularly limited, and an inorganic coating may be formed in the lower layer, an organic coating may be disposed in the upper layer, and vice versa.
[0024]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are not intended to limit the present invention, and any design changes based on the gist of the preceding and following descriptions are technical aspects of the present invention. It is included in the range.
[0025]
Example 1
An electrogalvanized steel sheet (Zn adhesion amount per side: 20 g / m ² ) or hot dip galvanized steel sheet (Zn adhesion amount per side: 60 g / m ² ) prepared as a conventional method was used as the base plating steel plate, Compounds of La and Ce as rare earth elements and compounds of Zr and Ti as group IVa elements were applied by the cathodic electrolytic treatment method under the following conditions. The processing conditions are shown below.
[0026]
<Cathode electrolysis method>
Using a treatment liquid containing 0.02 to 0.05 mol / L of La, Ce, Zr, and Ti ions alone or in combination, electrolytic treatment was performed using the base plated steel plate as a cathode and the platinum plated Ti plate as an anode. For La and Ce, sulfate is dissolved. For Zr and Ti, potassium fluoride Zr or potassium fluoride Ti is dissolved in ion-exchanged water. Further, the pH is adjusted with sulfuric acid as necessary, and then cathodic electrolysis treatment is performed. Used as a liquid.
-Treatment solution pH: 1.5-4.5
・ Processing liquid temperature: 50 ℃
・ Current density: 5-50A / dm ²
・ Electricity: O. 1-1C / cm ²
・ Liquid flow velocity: 1.3m / sec
[0027]
In addition, a chrome-treated plated steel sheet was prepared as a comparative material. In the case of an electrogalvanized steel sheet, a chromate film was applied by spray treatment using a reactive chromate treatment solution (Ginchrome ZM359) manufactured by Nippon Parkerizing. In the case of a hot dip galvanized steel sheet, a mixed solution of 40% reduced chromic acid and chromic anhydride was applied to the plating surface with a drawing roll and then dried. In all cases, the adhesion amount in terms of metallic Cr was adjusted to 20 mg / m ² .
[0028]
A mixture film of rare earth elements and / or group IVa element compounds obtained by the above method is obtained by using an X-ray photoelectron spectrometer (PHI5400MC manufactured by Parkin Elmer Co., Ltd.) and a 1 s narrow region of oxygen at five positions in the film thickness direction. The photoelectron spectrum is measured and the constituent ratio of the oxide and hydroxide is measured. At the same time, the number of moles A of oxygen atoms constituting the oxide and the number of moles B of oxygen atoms constituting the hydroxide are determined by the above-described method. Average A / B was calculated. As the X-ray source, MgKα ray with an output of 400 W was used, the analysis region was 1.1 mmφ, and Ar ions were used for sputtering the coating. As for the adhesion amount, the coating film is dissolved in 1: 1 hydrochloric acid together with the plating layer, and then fixed to a predetermined amount and contained in an inductively coupled plasma emission spectrometer (ICPV-1000 manufactured by Shimadzu Corporation). Or the IVa group element was quantitatively analyzed.
[0029]
The following performance evaluation test was implemented about the obtained plated steel plate.
[0030]
(1) White rust resistance The white rust resistance of the flat plate portion was evaluated by a salt spray test according to JIS Z2371. The white rust generation area rate after 48 hours of the salt spray test (SST) was determined according to the following criteria.
◎: Less than 5% ○: 5% or more and less than 10% ×: 10% or more and less than 50% (2) Coating film adhesion After the melamine-alkyd coating was applied by bar coating, the primary coating film adhesion and The secondary coating film adhesion was evaluated according to the following criteria.
[0031]
<Coating conditions>
・ Paint: Amirac 1000 (manufactured by Kansai Paint)
・ Coating thickness: 20 ± 1μm
-Baking conditions: 130 ° C x 20 minutes [0032]
<Evaluation of coating film adhesion>
Put 10 × 10 (100) square grids of 1 mm square on the coated plate with a cutter knife, perform Erichsen overhanging 6 mm in height, perform a tape peeling test, and check the remaining mass after peeling the coating film. The eyes were measured and the primary adhesion was evaluated. Further, the coated plate was immersed in boiling water for 1 hour and then taken out. A tape peeling test was immediately conducted in the same manner as described above to evaluate the secondary adhesion. The evaluation criteria are as follows.
A: Number of remaining squares of the coating film is 100%
○: Remaining coating cell number 90% or more and less than 100% ×: Remaining coating cell number 90% or less
The obtained results are shown in Table 1. In the column of “Plated steel sheet type” in the table, EG means electrogalvanized steel sheet, and GI means hot dip galvanized steel sheet. In addition, in the “existing state of oxides and hydroxides” in the table, ○ indicates that the treatment layer is mainly composed of rare earth elements and / or Group IVa element oxides and hydroxides, The vicinity of the interface is mainly composed of oxides, and the vicinity of the surface has a gradient mixed composition mainly composed of hydroxides, and Δ is mainly composed of oxides and hydroxides of rare earth elements and / or group IVa elements. The gradient composition according to the present invention has a gradient composition. However, the oxide or hydroxide is extremely large or small near the interface or near the surface, or the thickness of each layer is extremely large. The case where the A / B value of the present invention is not satisfied because it is thick or thin is shown. X indicates that the treated layer does not belong to any of the above-mentioned ○ or Δ.
[0034]
[Table 1]

[0035]
No. 1 to 37 are examples of the present invention in which the mixture film according to the present invention is formed as a treatment layer. Excellent white rust resistance and coating film adhesion equivalent to or better than the chromate treatment materials shown in Nos. 38 and 39 were exhibited. On the other hand, the processed layer is not the component composition distribution according to the present invention. In the case of 40-47, corrosion resistance and / or coating-film adhesiveness were not enough. Further, Comparative Example No. in which the amount of deposited metal equivalent of the oxide and hydroxide of the rare earth element and / or group IVa element is not appropriate. Even in the case of 48 to 51, the corrosion resistance and / or coating film adhesion was not sufficient.
[0036]
Example 2
In the same manner as in Example 1, a galvanized steel sheet to which a rare earth element or IVa group element compound was added was produced. When the film thickness after drying is mainly composed of organic matter by drawing and rolling the film mainly composed of organic or inorganic matter on the obtained plated steel sheet, O. When the main component was an inorganic substance, the coating was carried out to a thickness of 0.1 μm. For films mainly composed of organic substances, polyester resins mainly composed of colloidal silica and wax, and for films mainly composed of inorganic substances, mainly composed of lithium silicate and colloidal silica, polyester resins, waxes and silane cups. What added the ring agent was used.
[0037]
About the obtained organic or inorganic film-coated plated steel sheet, white rust resistance and coating film adhesion were investigated in the same manner as in Example 1. However, for white rust resistance, the white rust generation area ratio after 120 hours of the salt spray test (SST) was investigated according to the same evaluation criteria as in Example 1. The obtained results are summarized in Table 2.
[0038]
[Table 2]

[0039]
No. Nos. 1 to 17 are examples of the present invention in which the mixture film according to the present invention is formed as a treatment layer. It exhibited excellent white rust resistance and coating film adhesion equivalent to or better than the chromate treated materials shown in Nos. 26 and 27. In contrast, Comparative Example No. in which the treatment layer was not the mixture film according to the present invention. In the case of 18-23, corrosion resistance and / or coating-film adhesiveness were not enough. Further, Comparative Example No. in which the amount of deposited metal equivalent of the oxide and hydroxide of the rare earth element and / or group IVa element is not appropriate. Even in the case of 24 to 25, corrosion resistance and / or coating film adhesion was not sufficient.
[0040]
【The invention's effect】
Since the present invention is configured as described above, a zinc-based plated steel sheet that exhibits excellent white rust resistance and coating film adhesion can be provided without using any chrome treatment harmful to the environment. It was.

Claims (5)

A zinc-based plated steel sheet in which one or more compound films of rare earth elements and / or group IVa elements are formed on a plating surface,
The above-mentioned compound film is mainly composed of one or more kinds of rare earth elements and / or group IVa oxides and hydroxides, mainly in the vicinity of the interface with the plating layer, and in the vicinity of the surface. all SANYO mainly composed of hydroxide,
The number of moles of oxygen atoms in the oxide of a rare earth element and / or IV a group element in the compound layer A, the number of moles of oxygen atoms constituting the hydroxides of rare earth elements and / or IV a group element B when the value of a / B is O. A galvanized steel sheet excellent in white rust resistance and coating film adhesion, characterized by being 2 or more and 10 or less .   The galvanized steel sheet according to claim 1, wherein the composition in the depth direction of the compound film is composed of a gradient mixed composition of the oxide and the hydroxide. Adhesion amount of one or more oxides and mixtures film mainly a hydroxide of a rare earth element and / or group IVa elements, to claim 1 or 2 which is 5～1500Mg / m ² in terms of metal The galvanized steel sheet described. The galvanized steel sheet according to any one of claims 1 to 3 , wherein the rare earth element is La, Ce, Y, and the group IVa element is Zr, Ti. An organic or / and inorganic coating is formed to a thickness of 0.01 to 20 µm on the upper layer of the compound coating in the galvanized steel sheet according to any one of claims 1 to 4. Composite coated galvanized steel sheet.