Surface treatment of metal sheets

Abstract

The surface-treated metal plate comprises: a steel plate; a zinc-containing plating layer formed on the steel plate; and a coating formed on the plating layer, the coating comprising an organic silicon compound, a phosphate compound and a fluorine compound, and satisfying any one or more of the following conditions: arithmetic mean height Sa: 0.1 to 10 nm, maximum height Sz: 1 to 1000 nm, and root mean square roughness Sq: 0.1 to 100 nm, when the surface roughness in a rectangular region of the surface of the coating with one side of 1 μm is expressed by arithmetic mean height Sa, maximum height Sz, and root mean square roughness Sq, respectively.

Description

Technical Field

[0001] The invention relates to a surface-treated metal sheet.

[0002] This application claims priority based on Special Application No. 2020-189316 filed in Japan on November 13, 2020, and the contents of which are incorporated herein. Background Art

[0003] Steel sheets having a zinc-containing plating layer have been widely subjected to rust-proof treatment using chromates such as hexavalent chromate, and are covered with organic resins or subsequently coated with various coatings to further impart high corrosion resistance, fingerprint resistance, scratch resistance, lubricity, etc., as needed.

[0004] In recent years, there is a trend to avoid chromate treatment in the context of rising environmental issues. Since the chromate treatment layer itself has high corrosion resistance and paint adhesion, it is expected that these properties will be significantly reduced if the chromate treatment is not performed. Therefore, it is required to form a rust-proof layer with good corrosion resistance and paint adhesion by only one-stage treatment using an organic resin without performing a base treatment using a chromate treatment.

[0005] Patent document 1 describes a surface metal-treated material having a composite coating on the surface of the metal material, wherein the composite coating contains the respective components by coating a surface-treated metal agent comprising an organic silicon compound, at least one fluorine compound selected from fluorotitanic acid or fluorozirconic acid, phosphoric acid and a vanadium compound and drying the coating.

[0006] Patent document 2 describes a surface metal-treated material having a composite coating on the surface of the metal material, wherein the composite coating contains an organic silicon compound, at least one fluorine compound selected from fluorotitanic acid or fluorozirconic acid, phosphoric acid, a vanadium compound and a lubricant, wherein the lubricant is at least one selected from water-dispersible polyethylene wax, polypropylene wax and polytetrafluoroethylene, and has a number average particle size of 0.01 μm to 1.0 μm and a softening temperature of above 100°C.

[0007] Patent Document 3 describes a chromate-free surface-treated metal material having a coating formed by applying an aqueous treatment agent containing an organic silicon compound and an organic fluorine compound having a perfluoroalkyl group to the surface of the metal material and then drying or baking the coating.

[0008] Patent document 4 describes a surface-treated metal material having a composite film on the surface of the metal material, wherein the composite film includes an organic silicon compound as a film-forming component, and includes at least one metal compound selected from a titanium compound and a zirconium compound, a phosphoric acid compound, and a fluorine compound as an inhibitor component, and the existence ratio of the cyclic siloxane bond to the chain siloxane bond in the organic silicon compound is measured by 1090 to 1100 cm-1 obtained by FT-IR reflection method to indicate the cyclic siloxane bond. -1 The absorbance W1 is similar to the absorbance at 1030-1040 cm-1 representing the chain siloxane bond. -1 The absorbance W2 ratio W1 / W2 is 1.0 to 2.0.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent No. 4776458

[0012] Patent Document 2: Japanese Patent No. 5335434

[0013] Patent Document 3: Japanese Patent No. 4709942

[0014] Patent Document 4: Japanese Patent No. 5336002 Summary of the invention

[0015] Problems to be solved by the invention

[0016] However, the lubricity performance of the plated steel sheet formed with a coating by chemical conversion treatment depends on the coating on the outermost surface. The lubricity is evaluated by the coefficient of dynamic friction of the coating surface, etc. When the conventional chromate coating is replaced by a chromate-free coating, the chromate-free coating as a substitute is required to have the same degree of lubricity as the chromate coating. If the lubricity of the chromate-free coating decreases, when multiple plated steel sheets are stacked flat, it becomes easy to cause loose packing (load collapse) which is not a problem for the chromate coating. In addition, if the lubricity of the chromate-free coating becomes different from the lubricity of the chromate coating, for example, when the plated steel sheet is subjected to roll forming processing, it becomes necessary to readjust the setting conditions of the processing. However, attempts to make the lubricity of the chromate-free coating close to the lubricity of the chromate coating have not been studied so far.

[0017] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface-treated metal plate having a coating having lubricity comparable to that of a conventional chromate coating and having excellent corrosion resistance and coating adhesion.

[0018] Means for solving problems

[0019] The gist of the present invention made in order to solve the above-mentioned problems is as follows.

[0020] [1] A surface-treated metal plate according to one embodiment of the present invention comprises:

[0021] Steel plates;

[0022] a plating layer including zinc formed on the above-mentioned steel sheet; and

[0023] The film formed on the above-mentioned plating layer,

[0024] The film comprises an organic silicon compound, a phosphoric acid compound and a fluorine compound.

[0025] When the surface roughness in a rectangular area with one side of the surface of the above-mentioned film is expressed as an arithmetic mean height Sa, a maximum height Sz, and a root mean square roughness Sq, respectively, one or more of the arithmetic mean height Sa: 0.10~10.0nm, the maximum height Sz: 1.0~1000nm and the root mean square roughness Sq: 0.10~100nm is satisfied.

[0026] [2] According to the surface-treated metal plate described in [1] above, when the surface roughness in a rectangular area with one side of the surface of the above-mentioned film being 5 μm is expressed by the arithmetic mean height Sa, the maximum height Sz, and the root mean square roughness Sq, respectively, it can also satisfy one or more of the following conditions: arithmetic mean height Sa: 0.10~10nm, maximum height S: 1.0~1000nm, and root mean square roughness Sq: 0.10~100nm.

[0027] [3] The surface-treated metal plate according to [1] or [2], wherein a rectangular region with a side of 1 μm on the surface of the film may contain 1 to 100 granular organic silicon compounds with a major axis of 10 nm to 300 nm.

[0028] [4] The surface-treated metal sheet according to any one of [1] to [3] above, wherein the average chemical composition of the plating layer may contain, in terms of mass %, the following:

[0029] Al: more than 4.0% and less than 25.0%,

[0030] Mg: more than 1.0% and less than 12.5%,

[0031] Sn: 0% to 20%,

[0032] Bi: 0% or more and less than 5.0%,

[0033] In: 0% or more and less than 2.0%,

[0034] Ca: 0% to 3.0%,

[0035] Y: 0% to 0.5%,

[0036] La: 0% or more and less than 0.5%,

[0037] Ce: 0% or more and less than 0.5%,

[0038] Si: 0% or more and less than 2.5%,

[0039] Cr: 0% or more and less than 0.25%,

[0040] Ti: 0% or more and less than 0.25%,

[0041] Ni: 0% or more and less than 0.25%,

[0042] Co: 0% or more and less than 0.25%,

[0043] V: 0% or more and less than 0.25%,

[0044] Nb: 0% or more and less than 0.25%,

[0045] Cu: 0% or more and less than 0.25%,

[0046] Mn: 0% or more and less than 0.25%,

[0047] Fe: 0% to 5.0%,

[0048] Sr: 0% or more and less than 0.5%,

[0049] Sb: 0% or more and less than 0.5%,

[0050] Pb: 0% or more and less than 0.5%,

[0051] B: 0% or more and less than 0.5%,

[0052] The remainder is Zn and impurities.

[0053] Effects of the Invention

[0054] According to the above aspect of the present invention, it is possible to provide a surface-treated metal sheet having a coating having lubricity comparable to that of a conventional chromate coating and having excellent corrosion resistance and coating adhesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic cross-sectional view of the surface-treated metal plate according to the present embodiment.

[0056] Figure 2This is a schematic diagram for explaining the method for producing a surface-treated metal plate according to the present embodiment. DETAILED DESCRIPTION

[0057] In order to realize a film having the same degree of lubricity as the conventional chromate film and having both coating adhesion and corrosion resistance, the inventors of the present invention have conceived a film design that controls the roughness of a microscopic region on the film surface. Generally speaking, the roughness is measured in the region of "mm (millimeter)" or "cm (centimeter)" as a measurement region using a roughness meter or the like. However, the inventors of the present invention believe that it is the roughness in the micrometer region that actually controls the lubricity (dynamic friction coefficient) and coating adhesion, and thus designed a chromate-free film as described below.

[0058] That is, it was found that in order to improve the coating adhesion and control the lubricity (dynamic friction coefficient) through physical action, when the surface roughness in a rectangular (including square) area with a side of 1 μm is represented by the arithmetic mean height Sa, the maximum height Sz, and the root mean square roughness Sq, respectively, by satisfying one or more of the conditions of arithmetic mean height Sa: 0.10~10.0nm, maximum height Sz: 1.0~1000nm and root mean square roughness Sq: 0.10~100nm, the lubricity (dynamic friction coefficient) can be made equivalent to that of the chromate coating.

[0059] Furthermore, it was found that lubricity can be more suitably controlled by satisfying at least one of the following conditions: arithmetic mean height Sa of 0.10 to 10.0 nm, maximum height Sz of 1.0 to 1000 nm, and root mean square roughness Sq of 0.10 to 100 nm in a rectangular region with a side length of 5 μm.

[0060] Furthermore, it was found that, in order to improve the coating adhesion based on chemical action, by setting the main component constituting the coating to an organic silicon compound, the lubricity (dynamic friction coefficient) can be made equal to that of the chromate coating, and the coating adhesion can be improved.

[0061] Furthermore, the inventors have found that it is effective to contain a phosphoric acid compound and a fluorine compound in the film as components that improve the corrosion resistance without affecting the lubricity and the adhesion of the coating film.

[0062] It was found that in order to realize the above design concept, after applying the surface treatment metal agent with a viscosity of 0.5mPa·s to 2.0mPa·s, it is immediately naturally dried for 0.2 to 10 seconds in an atmosphere of 10 to 35°C and a relative humidity of 30 to 90% (the first drying process), and then further heated and dried (the second drying process), so that the roughness of the tiny area on the surface of the film can be controlled within the above range.

[0063] Hereinafter, a surface-treated metal plate as one embodiment of the present invention will be described.

[0064] The surface-treated metal plate of the present embodiment is the following surface-treated metal plate: it comprises: a steel plate; a plating layer containing zinc formed on the steel plate; and a film formed on the plating layer, the film containing an organic silicon compound, a phosphate compound and a fluorine compound, and when the surface roughness in a rectangular area on the surface of the film with one side being 1 μm is expressed by the arithmetic mean height Sa, the maximum height Sz and the root mean square roughness Sq, respectively, it satisfies one or more of the conditions of arithmetic mean height Sa: 0.10~10nm, maximum height Sz: 1.0~1000nm and root mean square roughness Sq: 0.10~100nm.

[0065] In addition, when the surface roughness in a rectangular area of ​​the surface of the film with one side being 5 μm is represented by the arithmetic mean height Sa, the maximum height Sz, and the root mean square roughness Sq, respectively, it is preferred to satisfy one or more of the arithmetic mean height Sa: 0.10 to 10.0 nm, the maximum height Sz: 1.0 to 1000 nm, and the root mean square roughness Sq: 0.10 to 100 nm.

[0066] Furthermore, it is preferred that 1 to 100 granular organic silicon compounds having a major axis of 10 nm to 300 nm are contained in a rectangular region having a side of 1 μm on the surface of the film.

[0067] In the following description, the "%" expression of the content of each element in the chemical composition means "mass %". In addition, the numerical range expressed using "to" means a range that includes the numerical values ​​recorded before and after the "to" as the lower limit and the upper limit. In addition, the numerical range in which "exceeds" or "is lower than" is annotated with respect to the numerical values ​​recorded before and after the "to" means a range that does not include these numerical values ​​as the lower limit or the upper limit.

[0068] <Steel Plate 11>

[0069] like Figure 1As shown in , the surface treated metal plate 1 of this embodiment can obtain the same level of lubricity as that formed with a chromate film through the plating layer 12 and the composite film 13. In addition, the corrosion resistance of the surface treated metal plate 1 of this embodiment and the coating adhesion of the film are also excellent. Therefore, there is no special limitation on the steel plate 11. It can be determined according to the product to be applied, the required strength or plate thickness, etc. The material of the steel plate 11 can be applied to various steel plates such as ordinary steel, pre-plated Ni steel, Al-killed steel, ultra-low carbon steel, high carbon steel, various high-tensile steels, and a part of high-alloy steel (steel containing strengthening elements such as Ni and Cr, etc.). In addition, there is no special limitation on the conditions such as the manufacturing method of the steel plate 11 (hot rolling method, pickling method, cold rolling method, etc.). Furthermore, as the steel plate 11, a steel plate with a metal film or alloy film with a thickness of less than 1μm formed with Zn, Ni, Sn or their alloy system can also be used. As an example of the steel plate 11, for example, a hot-rolled steel plate described in JIS G3193:2008 and a cold-rolled steel plate described in JIS G3141:2017 are mentioned.

[0070] <Plating 12>

[0071] The coating 12 provided in the surface-treated metal plate 1 of the present embodiment is formed on the surface of the steel plate 11 and contains zinc. The zinc content may be, for example, 50% by mass or more. In addition, aluminum may also be contained in the coating 12. In addition, magnesium may be further contained. The corrosion resistance of the coating 12 is improved in the following order: a coating containing zinc; a coating containing zinc and aluminum; a coating containing zinc, aluminum and magnesium. As for the surface-treated metal plate 1 of the present embodiment, any of these coatings may be provided. In the case of containing aluminum, it may be less than 25.0% by mass, and in the case of containing magnesium, it may be less than 12.5% ​​by mass.

[0072] As the coating 12 containing zinc, for example, a hot-dip galvanized layer or an electro-galvanized layer formed of zinc and impurities as the remainder can be exemplified. In addition, as the coating 12 containing zinc and aluminum, for example, a hot-dip galvanized layer formed of zinc, aluminum, and impurities as the remainder, and a hot-dip galvanized layer further containing an additive element can be exemplified. Furthermore, as the coating 12 containing zinc, aluminum, and magnesium, for example, a hot-dip galvanized layer formed of zinc, aluminum, magnesium, and impurities as the remainder, and a hot-dip galvanized layer further containing an additive element can be exemplified.

[0073] Hereinafter, the chemical composition of the plating layer 12 including zinc, aluminum, and magnesium will be described.

[0074] The plating layer 12 preferably has a chemical composition comprising Al: more than 4.0% and less than 25.0%, Mg: more than 1.0% and less than 12.5%, Sn: 0% to 20%, Bi: more than 0% and less than 5.0%, In: more than 0% and less than 2.0%, Ca: 0% to 3.0%, Y: 0% to 0.5%, La: more than 0% and less than 0.5%, Ce: more than 0% and less than 0.5%, Si: more than 0% and less than 2.5%, Cr: more than 0% and less than 0.25%, Ti: more than 0% and less than 0. .25%, Ni: 0% or more and less than 0.25%, Co: 0% or more and less than 0.25%, V: 0% or more and less than 0.25%, Nb: 0% or more and less than 0.25%, Cu: 0% or more and less than 0.25%, Mn: 0% or more and less than 0.25%, Fe: 0% to 5.0%, Sr: 0% or more and less than 0.5%, Sb: 0% or more and less than 0.5%, Pb: 0% or more and less than 0.5%, B: 0% or more and less than 0.5%, and the remainder is Zn and impurities.

[0075] [Al: more than 4.0% and less than 25.0%]

[0076] Al is an element effective for ensuring corrosion resistance in the plating layer 12 containing aluminum (Al), zinc (Zn), and magnesium (Mg). In order to fully obtain the above-mentioned effects, it is preferable to set the Al content to more than 4.0%.

[0077] On the other hand, if the Al content is 25.0% or more, the corrosion resistance of the cut end surface of the plating layer 12 decreases. Therefore, the Al content is preferably less than 25.0%.

[0078] [Mg: more than 1.0% and less than 12.5%]

[0079] Mg is an element having the effect of improving the corrosion resistance of the plating layer 12. When the above-mentioned effect is to be fully obtained, it is preferable to set the Mg content to more than 1.0%.

[0080] On the other hand, if the Mg content is 12.5% ​​or more, the effect of improving the corrosion resistance is saturated, and the workability of the coating layer 12 is reduced. In addition, if the Mg content is 12.5% ​​or more, there will be problems in manufacturing such as an increase in the amount of dross generated in the coating bath. Therefore, it is preferable to set the Mg content to less than 12.5%.

[0081] The plating layer 12 may contain Al and Mg, and the balance may contain Zn and impurities. However, the following elements may be further contained as necessary.

[0082] [Sn: 0% to 20%]

[0083] [Bi: 0% or more and less than 5.0%]

[0084] [In: 0% or more and less than 2.0%]

[0085] If these elements are contained in the plating layer 12 , a Mg 2 Sn phase, a Mg 3 Bi 2 phase, a Mg 3 In phase, or the like is formed as a new intermetallic compound phase in the plating layer 12 .

[0086] These elements do not form an intermetallic compound phase with any of Zn and Al constituting the main body of the plating layer 12, and only form an intermetallic compound phase with Mg. If a new intermetallic compound phase is formed, the weldability of the plating layer 12 will change significantly. Since any intermetallic compound phase has a high melting point, it will not evaporate after welding and will exist as an intermetallic compound phase. Even Mg, which is originally easy to form MgO due to oxidation due to welding heat, will not be oxidized by forming an intermetallic compound phase with Sn, Bi, and In, and it becomes easy to remain as the plating layer 12 in the state of an intermetallic compound phase after welding. Therefore, if the above-mentioned elements are present in the plating layer 12, the corrosion resistance and chemical corrosion resistance are improved, and the corrosion resistance around the weld is improved. In the case of obtaining the above-mentioned effects, it is preferable to set the content to 0.05% or more.

[0087] Among these elements, Sn is a low melting point metal and can be easily contained without damaging the properties of the plating bath, so it is preferred. The upper limits of these elements can be set to 20% or less for Sn, less than 5.0% for Bi, and less than 2.0% for In.

[0088] [Ca: 0% to 3.0%]

[0089] If Ca is contained in the plating layer 12, the amount of dross that is easily formed during the plating operation is reduced as the Mg content increases, and the plating manufacturability is improved. Therefore, Ca may be contained. When this effect is desired, the Ca content is preferably set to 0.1% or more.

[0090] On the other hand, if the Ca content is high, the corrosion resistance of the flat surface portion of the plating layer 12 itself tends to deteriorate, and the corrosion resistance around the weld may also deteriorate. Therefore, even when Ca is contained, the Ca content is preferably 3.0% or less.

[0091] [Y: 0%~0.5%]

[0092] [La: 0% or more and less than 0.5%]

[0093] [Ce: 0% or more and less than 0.5%]

[0094] Y, La, and Ce are elements that contribute to improving corrosion resistance. In order to obtain this effect, it is preferred that 0.05% or more of each of Y, La, and Ce be contained.

[0095] On the other hand, if the contents of these elements become excessive, the viscosity of the plating bath increases, and the preparation of the plating bath itself often becomes difficult, and a surface-treated metal plate 11 having good plating properties cannot be produced. Therefore, even when these elements are contained, it is preferred to set the Y content to 0.5% or less, the La content to less than 0.5%, and the Ce content to less than 0.5%.

[0096] [Si: 0% or more and less than 2.5%]

[0097] Si is an element that forms a compound with Mg and contributes to improving corrosion resistance. In addition, Si is also an element that has the following effects: when forming the plating layer 12 on the steel sheet 11, it suppresses the alloy layer formed between the surface of the steel sheet 11 and the plating layer 12 from being too thick, and improves the adhesion between the steel sheet 11 and the plating layer 12. When these effects are desired, the Si content is preferably set to 0.1% or more. More preferably, it is 0.2% or more.

[0098] On the other hand, if the Si content is set to 2.5% or more, excessive Si will precipitate in the coating layer 12, resulting in not only reduced corrosion resistance but also reduced workability of the coating layer 12. Therefore, the Si content is preferably set to less than 2.5%, more preferably 1.5% or less.

[0099] [Cr: 0% or more and less than 0.25%]

[0100] [Ti: 0% or more and less than 0.25%]

[0101] [Ni: 0% or more and less than 0.25%]

[0102] [Co: 0% or more and less than 0.25%]

[0103] [V: 0% or more and less than 0.25%]

[0104] [Nb: 0% or more and less than 0.25%]

[0105] [Cu: 0% or more and less than 0.25%]

[0106] [Mn: 0% or more and less than 0.25%]

[0107] Cr, Ti, Ni, Co, V, Nb, Cu, and Mn are elements that contribute to improving corrosion resistance. In order to obtain this effect, the content of each element is preferably set to 0.05% or more.

[0108] On the other hand, if the contents of these elements become excessive, the viscosity of the plating bath increases, and the preparation of the plating bath itself often becomes difficult, and a surface-treated metal plate 1 having good plating properties cannot be produced. Therefore, the contents of each element are preferably set to less than 0.25%.

[0109] [Fe: 0% to 5.0%]

[0110] Fe is an element that is inevitably mixed into the plating layer 12 as an impurity when the plating layer 12 is manufactured. Fe may be contained up to about 5.0%, and within this range, the adverse effect on the effect of the surface metal treatment plate 11 of this embodiment is small. On the other hand, if the Fe content exceeds 5.0%, the corrosion resistance of the plating layer 12 may be reduced. Therefore, it is preferable to set the Fe content to 5.0% or less.

[0111] [Sr: 0% or more and less than 0.5%]

[0112] [Sb: 0% or more and less than 0.5%]

[0113] [Pb: 0% or more and less than 0.5%]

[0114] When Sr, Sb, and Pb are contained in the plating layer 12, the appearance of the plating layer 12 changes, zinc spangles are formed, and improvement of metallic luster is confirmed. When this effect is desired, the content of each of Sr, Sb, and Pb is preferably set to 0.05% or more.

[0115] On the other hand, if the contents of these elements become excessive, the viscosity of the plating bath increases, and the preparation of the plating bath itself often becomes difficult, and a surface-treated metal plate 1 having good plating properties cannot be produced. Therefore, it is preferred that the Sr content be less than 0.5%, the Sb content be less than 0.5%, and the Pb content be less than 0.5%.

[0116] [B: 0% or more and less than 0.5%]

[0117] B is an element that forms various intermetallic compound phases by combining with Zn, Al, and Mg when contained in the plating layer 12. The intermetallic compound has an effect of improving LME (liquid metal embrittlement). When this effect is desired, the B content is preferably set to 0.05% or more.

[0118] On the other hand, if the B content becomes excessive, the melting point of the plating bath rises significantly, the plating workability deteriorates, and the surface-treated metal plate 1 having good plating properties cannot be obtained. Therefore, the B content is preferably set to less than 0.5%.

[0119] The coating weight of the plating layer 12 is not limited, but is preferably 10 g / m2 in order to improve corrosion resistance.2 On the other hand, even if the adhesion amount exceeds 200g / m 2 , the corrosion resistance is also saturated, and it becomes economically disadvantageous. Therefore, it is preferably 200g / m 2 the following.

[0120] <Coating 13>

[0121] The coating 13 provided on the surface of the plating layer 12 of the surface-treated metal plate 1 of the present embodiment comprises an organosilicon compound, a phosphoric acid compound and a fluorine compound. In the coating 13, a zirconium compound may be further included, and a vanadium compound may be included. In addition, the coating 13 of the present embodiment does not contain a Cr compound and is a so-called chromate-free coating. By including an organosilicon compound, a phosphoric acid compound and a fluorine compound in the coating 13, corrosion resistance and coating adhesion can be imparted to the surface-treated metal plate 1.

[0122] In the present embodiment, the organic silicon compound contained in the film 13 is not limited, and is, for example, an organic silicon compound obtained by combining a silane coupling agent (A) containing one amino group in the molecule and a silane coupling agent (B) containing one glycidyl group in the molecule at a solid content mass ratio [(A) / (B)] of 0.5 to 2.0, preferably 0.5 to 1.7.

[0123] The mixing ratio of the silane coupling agent (A) to the silane coupling agent (B) is preferably 0.5 to 2.0, preferably 0.5 to 1.7, in terms of the solid content mass ratio [(A) / (B)]. If the solid content mass ratio [(A) / (B)] is less than 0.5, the fingerprint resistance, bath stability, and black slag resistance may be significantly reduced. On the contrary, if the solid content mass ratio [(A) / (B)] exceeds 2.0, the water resistance may be significantly reduced, which is not preferred. [(A) / (B)] is more preferably 0.7 to 1.7, and even more preferably 0.9 to 1.1.

[0124] The silane coupling agent (A) containing one amino group is not particularly limited, and examples thereof include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, etc. The silane coupling agent (B) containing one glycidyl group in the molecule includes 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.

[0125] In the present embodiment, the phosphate compound contained in the film 13 is not particularly limited, and examples thereof include phosphoric acid, ammonium phosphate, potassium phosphate, sodium phosphate, etc. Among them, phosphoric acid is more preferred. When phosphoric acid is used, better corrosion resistance can be obtained.

[0126] Regarding the content of the phosphate compound in the film 13, if the average value of the ratio of the solid content mass of P derived from the phosphate compound to the solid content mass of Si derived from the organosilicon compound, that is, P / Si, is 0.15 to 0.25, the homogeneity of the film 13 can be maintained, which is preferred. By setting the average value of P / Si to 0.15 or more, there is no concern that the corrosion resistance will be reduced due to insufficient P. In addition, by setting the average value of P / Si to 0.25 or less, the water dissolution of the film 13 can be prevented.

[0127] In this embodiment, the fluorine compound contained in the film 13 is not particularly limited, and examples thereof include fluorides such as hydrofluoric acid, fluoroboric acid, fluorosilicic acid, and their water-soluble salts, and complex fluoride salts. Among them, hydrofluoric acid is more preferred. When hydrofluoric acid is used, more excellent corrosion resistance and coating properties can be obtained.

[0128] In the film 13 , if the average value of the solid mass ratio of F derived from the fluorine compound to the solid mass ratio of Si derived from the organic silicon compound, i.e., F / Si, is 0.01 to 0.15, it is preferable because corrosion resistance can be appropriately ensured while maintaining the homogeneity of the film 13 .

[0129] The film 13 may also contain a zirconium compound. The zirconium compound is not particularly limited, and examples thereof include fluorozirconic acid, ammonium hexafluorozirconate, zirconium sulfate, zirconium oxychloride, zirconium nitrate, zirconium acetate, and the like. Among them, fluorozirconic acid is more preferred. When fluorozirconic acid is used, more excellent corrosion resistance and coating properties can be obtained. In addition, fluorozirconic acid also acts as a fluorine compound, and is therefore preferred.

[0130] Furthermore, a vanadium compound may also be included in the film 13. The vanadium compound (V) is not particularly limited, and examples thereof include vanadium pentoxide V2O5, metavanadic acid HVO3, ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride VOCl3, vanadium trioxide V2O3, vanadium dioxide VO2, vanadium oxysulfate VOSO4, vanadium acetylacetonate VO(OC(=CH2)CH2COCH3)2, vanadium acetylacetonate V(OC(=CH2)CH2COCH3)3, vanadium trichloride VCl3, vanadophosphomolybdic acid, and the like. In addition, a vanadium compound obtained by reducing a pentavalent vanadium compound to a tetravalent to divalent vanadium compound with an organic compound having at least one functional group selected from a hydroxyl group, a carbonyl group, a carboxyl group, a primary to tertiary amino group, an amide group, a phosphoric acid group, and a phosphonic acid group may also be used.

[0131] In the film 13, if the average value of the ratio of the solid content mass of Zr derived from the zirconium compound to the solid content mass of Si derived from the organic silicon compound, i.e., Zr / Si, is 0.06 to 0.15, the homogeneity of the film 13 can be maintained, which is preferred. If the average value of Zr / Si is 0.06 or more, the barrier property becomes sufficient and there is no concern about the reduction of corrosion resistance. In addition, if the average value of Zr / Si is 0.15 or less, the corrosion resistance can be fully ensured, which is preferred.

[0132] In addition, in the film 13, if the average value of the ratio of the solid content mass of V derived from the vanadium compound to the solid content mass of Si derived from the organic silicon compound, that is, V / Si, is 0.010 to 0.200, it is preferable that the V compound is appropriately precipitated in the region with low corrosion resistance while maintaining the homogeneity of the film 13. If the average value of V / Si is 0.010 or more, V as a corrosion inhibitor becomes sufficient, so there is no concern about reduced corrosion resistance. In addition, if the average value of V / Si is 0.200 or less, there is no concern about water solubilization of the film.

[0133] F / Si, P / Si, Zr / Si, and V / Si can be measured using micro-area fluorescent X-rays.

[0134] Specifically, F / Si, P / Si, Zr / Si, and V / Si can be measured using micro-area fluorescence X-ray (made by AMETEK, energy dispersive micro-area fluorescence X-ray analyzer Orbis, tube voltage: 5 kV, tube current: 1 mA), with the X-ray source set to Rh and a spot size of φ30 μm. During the measurement, the mass percentages of F, P, Zr, V, and Si in the detectable elements constituting the film 13 are measured with a pixel count of 256×200 for an area of ​​about 2.3 mm in the horizontal direction and about 1.5 mm in the vertical direction on the surface of the film 13, and F / Si, P / Si, Zr / Si, and V / Si are calculated from the results.

[0135] The coating weight per surface of the film 13 is preferably 0.05 to 2.0 g / m 2 , more preferably 0.2 to 1.0 g / m 2 , and most preferably 0.3 to 0.6 g / m 2 If the amount of coating 13 deposited on each side is less than 0.05 g / m 2 If the coating weight is set to more than 2.0 g / m, the surface of the coating layer 12 cannot be fully covered, resulting in a significant decrease in corrosion resistance, which is not preferred. 2 , the effect of improving corrosion resistance is saturated, so as long as the upper limit is set to 2.0g / m 2 The following will do.

[0136] Next, the surface roughness of the film 13 according to the present embodiment will be described.

[0137] The film 13 of the present embodiment satisfies at least one of the following conditions: arithmetic mean height Sa: 0.10 to 10.0 nm, maximum height Sz: 1.0 to 1000 nm, and root mean square roughness Sq: 0.10 to 100 nm, when the surface roughness in a rectangular region with one side of its surface being 1 μm is represented by arithmetic mean height Sa, maximum height Sz, and root mean square roughness Sq, respectively.

[0138] In addition, when the surface roughness of the film 13 of the present embodiment in a rectangular area with one side of its surface being 5 μm is represented by the arithmetic mean height Sa, the maximum height Sz, and the root mean square roughness Sq, respectively, it preferably satisfies at least one of the arithmetic mean height Sa: 0.10 to 10.0 nm, the maximum height Sz: 1.0 to 1000 nm, and the root mean square roughness Sq: 0.10 to 100 nm.

[0139] The reasons for limiting the surface roughness are described below.

[0140] <Surface roughness in a rectangular area with a side of 1 μm>

[0141] The inventors of the present invention have found that in order to make the lubricity of the film 13 of the present embodiment close to the lubricity of the chromate film, it is necessary to evaluate the surface roughness of the film itself in a state where the influence of the surface roughness of the plating layer 12 is removed, that is, in a micron region (micro area). In order to obtain a film 13 having a lubricity equivalent to that of the conventional chromate film, first, it is necessary to accurately evaluate the lubricity of the film 13 itself. However, since the film 13 is formed on the plating layer 12, the surface roughness of the film 13 is affected by the surface roughness of the plating layer 12. In addition, if the surface roughness is measured in units of millimeters or centimeters as a measurement length, it will be affected by the relatively large concavities and convexities derived from the surface state of the plating layer 12, so it is difficult to accurately evaluate the lubricity of the film 13 itself. Therefore, the inventors conducted research and found that by setting the measurement area of ​​the surface roughness to a micro area of ​​micrometers, the influence of the surface roughness of the plating layer 12 is reduced, and it becomes possible to evaluate the surface roughness of the film itself. Specifically, the surface roughness measurement area was set to a rectangular (including square) area with a side of 1 μm. It was found that by finely controlling the surface roughness in this micro area in a manner to become a predetermined range described later, a film 13 having lubricity equivalent to that of a conventional chromate film can be obtained.

[0142] In addition, the film 13 has a surface roughness corresponding to the surface roughness of the coating 12. The surface roughness of the coating 12 is relatively large. When the surface roughness of the film 13 reflecting the surface roughness of the coating 12 is measured in a scale (unit) of millimeters to centimeters as a measuring length, it becomes a roughness of several μm to tens of μm. Therefore, if the contact area between the film 13 and the object when another object contacts the film 13 is observed microscopically, it becomes an area formed by a large number of point contact areas. Therefore, the inventors of the present invention recognize that in order to evaluate the lubricity of the surface of the film 13, it is preferred to evaluate the surface roughness in an area corresponding to the size of the point contact area. Then, the inventors of the present invention found that as a measurement area for surface roughness, a rectangular area with a side of 1 μm is used as a measurement area to appropriately evaluate the lubricity of the film 13.

[0143] <Arithmetic mean height Sa: 0.10 to 10.0 nm>

[0144] <Maximum height Sz: 1.0~1000nm>

[0145] <Root mean square roughness Sq: 0.10~100nm>

[0146] As parameters for evaluating the surface roughness in a rectangular region with a side of 1 μm of the film 13 of this embodiment, the arithmetic mean height Sa, the maximum height Sz, and the root mean square roughness Sq are used, and at least one of these conditions needs to be within a specified range. In order to make the lubricity of the film 13 close to the lubricity of the chromate film, the arithmetic mean height Sa is set within the range of 0.10 to 10 nm, the maximum height Sz is set within the range of 1.0 to 1000 nm, and the root mean square roughness Sq is set within the range of 0.10 to 100 nm. In order to make the lubricity of the film 13 reach the same level as the lubricity of the chromate film, any one of Sa, Sz and Sq can meet the above conditions. In order to more stably control the lubricity of the film 13, that is, to make the lubricity of the film 13 closer to the lubricity of the chromate film, it is preferred that Sa, Sz and Sq all meet the above ranges.

[0147] <Surface roughness in a rectangular area with a side of 5 μm>

[0148] In order to further reduce the influence of the surface roughness of the coating 12 and more accurately evaluate the surface roughness of the film 13 itself, it is preferred to determine the surface roughness in the rectangular region with one side being 5 μm. Specifically, in the film 13, the surface roughness in the rectangular region with one side being 5 μm is also preferably satisfied with the following provisions. The evaluation result of the surface roughness in the rectangular region with one side being 5 μm is more susceptible to the influence of the surface state of the coating 12 than the evaluation result in the rectangular region with one side being 1 μm. That is, it can be said that the evaluation of the surface roughness in the rectangular region with one side being 5 μm is a more rigorous evaluation than the evaluation in the rectangular region with one side being 1 μm. Therefore, in the present embodiment, by satisfying the following requirements for the surface roughness in the rectangular region with one side being 5 μm, it is possible to obtain a film 13 having the same level of lubricity as the conventional chromate film more stably.

[0149] <Arithmetic mean height Sa: 0.10 to 10.0 nm>

[0150] <Maximum height Sz: 1.0~1000nm>

[0151] <Root mean square roughness Sq: 0.10~100nm>

[0152] As parameters for evaluating the surface roughness in the rectangular region of the film 13 of this embodiment with a side of 5 μm, the arithmetic mean height Sa, the maximum height Sz, and the root mean square roughness Sq are used, similarly to the case of the 1 μm square region, and at least one of these conditions needs to be within the prescribed range. In order to make the lubricity of the film 13 close to the lubricity of the chromate film, the arithmetic mean height Sa is set to be within the range of 0.10 to 10.0 nm, the maximum height Sz is set to be within the range of 1.0 to 1000 nm, and the root mean square roughness Sq is set to be within the range of 0.10 to 100 nm. In addition, similarly to the prescribed case in the rectangular region of the film 13 with a side of 1 μm, in order to more stably control the lubricity of the film 13, that is, to make the lubricity of the film 13 closer to the lubricity of the chromate film, it is preferred that Sa, Sz, and Sq in the rectangular region of the film 13 with a side of 5 μm all meet the above ranges.

[0153] Next, the form and number density of the organic silicon compound in the film 13 will be described.

[0154] In the film 13 of the present embodiment, it is preferred that a granular organic silicon compound with a long diameter of 10nm to 300nm is included in a rectangular area with a side of 1μm on its surface in a range of 1 to 100. As a result, the lubricity of the film 13 is improved when the surface is oiled, and subsequent processing becomes easier. It is presumed that this is because: bulges are formed on the surface of the film 13 by the granular organic silicon compound, and an area that effectively retains the lubricating oil is formed in the gaps formed between the bulges accompanying the formation of the bulges. However, in the case where the long diameter of the organic silicon compound is 100nm to 300nm, if there are more than 100 in the above-mentioned rectangular area with a side of 1μm, the area for retaining the lubricating oil cannot be ensured. In addition, in the case where the long diameter is greater than 10nm and less than 100nm, in order to ensure the area for retaining the lubricating oil, it is necessary to ensure an area that is balanced with the long diameter, but if there are more than 100 in the above-mentioned rectangular area with a side of 1μm, it cannot be ensured. Therefore, the number of granular organosilicon compounds with a long diameter of 10nm to 300nm in a rectangular area with a side of 1μm is preferably less than 100. In addition, in order to ensure such an area for retaining lubricating oil, a ridge of a certain height or more is required. That is, when the size of the organosilicon compound that contributes to the formation of the ridge is too small, the lubricating oil cannot be fully retained, so the organosilicon compound with a long diameter of less than 10nm is excluded from the measurement object. On the other hand, when the size of the organosilicon compound that contributes to the formation of the ridge is too large, it may have an adverse effect on the lubricity of the film, so in this embodiment, the upper limit of the long diameter of the organosilicon compound as the measurement object is set to less than 300nm. It should be noted that the above-mentioned ridges derived from the organosilicon compound affect the above-mentioned surface roughness. Therefore, in order to more appropriately control Sa, Sz and Sq, it is preferred to control the number density of organosilicon compounds with a long diameter of 10nm to 300nm within the above range.

[0155] <Evaluation method>

[0156] The evaluation method is described below.

[0157] The method for measuring Sa, Sz, and Sq in a rectangular region with a side of 5 μm is set as follows.

[0158] In the surface of the film 13, as a measurement area of ​​5 μm square, an area of ​​20 parts is set. The setting position is set to be arbitrary. Then, based on the standard of ISO 25178, Sa, Sz and Sq are measured in each measurement area. The measuring device uses a scanning probe microscope (AFM5500M made by Hitachi High-Tech Science Corporation), and the measurement mode is set to dynamic focusing microscope mode. The probe uses SI-DF20, and the front end radius is set to 10nm. Then, the average value of the measurement results of each measurement area of ​​20 parts is used as Sa, Sz and Sq in a rectangular area with one side of 5 μm on the surface of the film.

[0159] Next, the method for measuring Sa, Sz, and Sq in a rectangular region with a side of 1 μm is set as follows.

[0160] In the surface of the film 13, 40 areas are set as 1 μm square measurement areas. The measurement areas of 20 of the 40 measurement areas are set within the 5 μm rectangular measurement areas of the above-mentioned 20 areas, and the remaining 20 areas are arbitrarily set from positions different from the 5 μm rectangular areas. Then, based on the standard of ISO 25178, Sa, Sz and Sq are measured in each measurement area. The measurement device, measurement mode, probe and front end radius are set as described above. Then, the average value of the measurement results of each of the 40 measurement areas is taken as Sa, Sz and Sq in a rectangular area with one side of 1 μm on the film surface.

[0161] Next, the number density of the organosilicon compound will be described.

[0162] The measurement area set in the measurement method of Sa, Sz and Sq in a rectangular area with a side of 1 μm is used to measure the number density of the organosilicon compound. In these multiple measurement areas, the image is measured in the measurement mode of the dynamic focus microscope. The organosilicon compound in the image is determined, and the number and size of the determined organosilicon compound are measured. The number and major diameter of the organosilicon compound are measured in each of the multiple measurement areas, i.e., the above-mentioned 40 locations, and the average value of the measurement results is used as the number and major diameter of the organosilicon compound in the rectangular area with a side of 1 μm on the surface of the film.

[0163] As a means of identifying the organosilicon compound in the image of the dynamic focusing microscope, an electron probe microanalyzer (EPMA) and a Fourier transform type microscopic infrared spectrophotometer (microscopic FT-IR) are used. The microscopic FT-IR measurement is set to a reflection measurement mode. Si is detected by EPMA, and the periphery of the detected Si is measured by microscopic FT-IR. When an infrared spectrum corresponding to the organic part of the organosilicon compound is obtained, the region where the infrared absorption spectrum is obtained is determined to be the organosilicon compound.

[0164] According to the surface treated metal plate of the present embodiment, it has the same degree of lubricity as the previous chromate film. In addition, according to the surface metal plate of the present embodiment, it is possible to improve corrosion resistance and coating adhesion. Here, lubricity can be evaluated by the dynamic friction coefficient. The dynamic friction coefficient of the film 13 of the present embodiment becomes 0.2 to 0.5, which is equivalent to the chromate film. In addition, regarding corrosion resistance, in the corrosion resistance evaluation using the salt spray test, after 72 hours, the white rust generation rate becomes less than 5%, showing excellent corrosion resistance. Furthermore, regarding the secondary adhesion after coating (grid (chessboard) peeling test after immersion in boiling water and after 30 minutes after white paint is applied), in the peeling test (grid peeling test) using 100 grids of 1 mm square, the number of peelings of the coating becomes less than 20, showing excellent secondary adhesion.

[0165] <Method of forming film>

[0166] Next, regarding a preferred method for manufacturing the surface-treated metal plate 1 of this embodiment, refer to Figure 2 Provide explanation. Figure 2 This is a schematic diagram for explaining a preferred method for manufacturing the surface-treated metal plate 1 of the present embodiment. Figure 2 In order to facilitate understanding of the features of the surface-treated metal plate 1 of the present embodiment, the features are sometimes shown enlarged for convenience, and the dimensional ratios of the components are not necessarily the same as the actual ones.

[0167] The surface metal treatment plate 1 of this embodiment can be obtained by a manufacturing method including the following steps: a plating step, in which a steel plate 11 is immersed in a plating bath containing Zn, Al, and Mg to form a coating 12 on the surface of the steel plate 11; a coating step, in which a surface treatment metal agent is coated on the coating 12; a first drying step, in which the surface treatment metal agent is immediately dried within a specified temperature and humidity range after being coated; and a second drying step, in which, after the first drying step, the steel plate 11 coated with the surface treatment metal agent is heated (baked) to form a coating containing an organic silicon compound, a phosphoric acid compound, and a fluorine compound.

[0168] [Plating process]

[0169] The plating step is not particularly limited, and may be performed by a common method so as to obtain sufficient plating adhesion.

[0170] Furthermore, there is no limitation on the method for manufacturing the steel sheet 11 to be subjected to the plating step.

[0171] [Coating process]

[0172] In the coating step, a surface treatment metal agent including an organic silicon compound, a phosphoric acid compound, and a fluorine compound is coated on the surface of the plated layer 12 of the steel sheet 11 .

[0173] It is preferable to adjust the ratio of the phosphoric acid compound and the fluorine compound to the organosilicon compound in accordance with the ratio of the target film.

[0174] The pH of the surface treatment metal agent can be adjusted using organic acids such as acetic acid and lactic acid, inorganic acids such as hydrofluoric acid, ammonium salts or amines. In addition, from the perspective of operability such as adhesion control and the morphology controllability of the outermost layer of the coating film of this embodiment, the viscosity of the surface treatment metal agent is preferably set to a range of 0.5 mPa·s to 2.0 mPa·s.

[0175] There is no limitation on the coating method.

[0176] For example, the coating can be performed using a roll coater, a bar coater, a sprayer, etc. When the coating is performed using a roll coater, the film thickness can be easily controlled by adjusting the peripheral speed ratio, and excellent productivity can be obtained.

[0177] [First drying step]

[0178] In the present embodiment, from the time when the surface treatment metal agent is applied to the coating layer 12 to form the coating 13A until the heating and drying (the second drying step) is started, a first drying step is carried out in an environment with an ambient temperature of 10 to 35°C and a humidity of 30 to 90% for 0.2 to 10 seconds. Through this first drying step, the surface roughness in a microscopic area on the surface of the film 13 finally obtained can be finely controlled in a manner to be within the above-mentioned prescribed range. In the present embodiment, from the time when the surface treatment metal agent is applied to the coating layer 12 until before heating and drying, the environment is maintained for more than 0.2 seconds, more preferably more than 0.5 seconds. It is believed that: Therefore, as Figure 2As shown in , the moisture in the outermost layer of the coating film 13A is evaporated, and as a result, a thin film 13B having a predetermined surface roughness as specified in this embodiment, i.e., a fine concavoconvex 13C, is formed on the outermost surface of the coating film 13A. The preferred range of the atmospheric temperature is 25 to 35° C., and the preferred range of the humidity is 50 to 80%.

[0179] When the humidity in the first drying process is lower than 30%, the drying is excessively performed. In addition, when the humidity exceeds 90%, the drying will not be fully performed, and the film 13 of the present embodiment cannot be formed. In addition, when the holding time is lower than 0.2 seconds, the drying will not be fully performed, and the film 13 of the present embodiment cannot be formed. It should be noted that even if the time from the formation of the coating 13A to the start of the heating drying (second drying process) described later is set to more than 10 seconds, the effect will not be improved, and the productivity will be reduced, so the holding time is set to less than 10 seconds. The time for maintaining the state of the coating 13A is preferably set to less than 10 seconds, and more preferably set to less than 5 seconds. In addition, when the atmospheric temperature in the first drying process is lower than 10°C, the drying will not be fully performed. In addition, when the atmospheric temperature exceeds 35°C, the drying is excessively performed, and the film 13 of the present embodiment cannot be formed.

[0180] It should be noted that the start time of the holding time in the first drying step is set to immediately after the surface treatment metal agent is applied, and the end time of the holding time is set to the start time of heating in the second drying step.

[0181] [Second drying step]

[0182] Next, the coating 13A maintained for a predetermined time in the first drying step is heated and dried to evaporate the water, thereby forming the coating 13. The temperature when the coating 13A is dried is selected in such a way that the volatile components in the surface treatment metal agent volatilize. Specifically, it is preferred that the maximum plate temperature (PMT) when the coating 13A is dried is within the range of 60 to 150°C. As a drying method when drying the coating 13A, for example, hot air drying or oven drying can be cited. Through such a second drying step, the morphology of the outermost layer of the coating obtained in the first drying step (micro unevenness 13C) will not be affected by the unevenness 12A of the coating 12, and the coating 13 can be formed while maintaining its morphology.

[0183] Through the above operations, the surface-treated metal plate of the present embodiment can be manufactured.

[0184] Example

[0185] The steel sheet was immersed in a plating bath to obtain metal sheets M-1 to M-7 having the plating layers described in Table 1. In the description of Table 1, for example, "Zn-19%Al-6%Mg-1.5%Sn-0.5%Ca-0.2%Si" means that the composition contains 19% Al, 6% Mg, 1.5% Sn, 0.5% Ca, and 0.2% Si by mass%, and the remainder is Zn and impurities. The unit area weight of the plating layer is set to 90 g / m 2 .

[0186] As the steel sheet, a cold-rolled steel sheet described in JIS G3141:2017 was used.

[0187] Regarding coating, after degreasing the surface of the steel sheet, a surface treatment metal agent containing an organic silicon compound, a fluorine compound, a phosphoric acid compound, and a vanadium compound (V compound) and adjusted in temperature was applied as a coating liquid to the steel sheet having the coating layer of M-1 to M-7 using a roll coater as shown in Table 2A and Table 2B. When the surface treatment metal agent was applied to the coating layer, the coating layer was subjected to Co treatment in some examples. The Co treatment referred to here refers to a treatment for the purpose of suppressing blackening, and specifically, a treatment of spraying a nitric acid Co aqueous solution on the surface of the coating layer.

[0188] The steel sheet having the plated layers on both sides was degreased using a degreasing agent (Nihon Parkerizing Co., Ltd. alkali degreasing agent, trade name: FINE CLEANERE 6406) (20 g / L bath, 60°C, spray for 10 seconds, spray pressure 50 kPa), and then rinsed with water for 10 seconds using a sprayer.

[0189] The viscosity of the surface treatment metal agent at 25° C. in each example was within a range of 0.5 mPa·s to 2.0 mPa·s.

[0190] In the table, regarding the "silane coupling agent" of the organic silicon compound, A1, A2, and B1 represent the following substances.

[0191] A1: 3-aminopropyltrimethoxysilane

[0192] A2: 3-aminopropyltriethoxysilane

[0193] B1: 3-Glycidoxypropyltrimethoxysilane

[0194] In the compound V, Z1 and Z2 represent the following substances.

[0195] Z1: Vanadyl Sulfate VOSO4

[0196] Z2: Vanadyl acetylacetonate VO(OC(=CH2)CH2COCH3)2

[0197] The surface treatment metal agent is applied, and the surface is naturally dried at the temperature and humidity recorded in Table 2E and Table 2F, and the coating retention time recorded in Table 2E and Table 2F (first drying process). After that, the steel plate is heated to the highest plate temperature in Table 2C to dry it and bake it (second drying process). The start of the coating retention time of the first drying process is set to just after the surface treatment metal agent is applied, and the end of the retention time is set to the start of heating in the second drying process.

[0198] The obtained films were evaluated for surface roughness, number density of the organosilicon compound, dynamic friction coefficient, corrosion resistance, and coating adhesion. The evaluation method was as follows.

[0199] <Sa, Sz, and Sq in a rectangular area with a side of 5 μm>

[0200] In the surface of the film, as a measurement area of ​​5 μm square, 20 areas are arbitrarily set. Sa, Sz and Sq are measured in each measurement area. The measurement device uses a scanning probe microscope (AFM5500M made by Hitachi High-Tech Science Corporation), and the measurement mode is set to dynamic focus microscope mode. The probe uses SI-DF20, and the front end radius is set to 10nm. The average value of the measurement results of the measurement areas of 20 parts is used as Sa, Sz and Sq in a rectangular area with a side of 5 μm on the surface of the film.

[0201] <Sa, Sz, and Sq in a rectangular region with a side of 1 μm>

[0202] On the surface of the film, 40 areas are set as measurement areas of 1 μm square. The measurement areas of 20 of the 40 measurement areas are set within the 5 μm rectangular measurement areas of the above-mentioned 20 areas, and the remaining 20 areas are arbitrarily set from positions different from the 5 μm rectangular areas. Sa, Sz and Sq are measured in each measurement area. The measurement device, measurement mode, probe and front end radius are set as described above. Then, the average value of the measurement results of each of the 40 measurement areas is used as Sa, Sz and Sq in the rectangular area of ​​the film surface with one side of 1 μm.

[0203] <Number Density of Organic Silicon Compounds>

[0204] The measurement area set in the measurement method of Sa, Sz and Sq in a rectangular area with a side of 1 μm is used for the measurement of the number density of the organosilicon compound. In these multiple measurement areas, the image is measured in the measurement mode of the dynamic focus microscope. The organosilicon compound in the image is determined, and the number and size of the determined organosilicon compound are measured. The number and major diameter of the organosilicon compound are measured in each of the multiple measurement areas, i.e., the above-mentioned 40 locations, and the average value of the measurement results is used as the number and major diameter of the organosilicon compound in the rectangular area with a side of 1 μm on the surface of the film. The average value is calculated from the measurement results in the multiple measurement areas and is used as the maximum diameter and number density.

[0205] As a means of identifying the organosilicon compound in the image of the dynamic focus microscope, an electron probe microanalyzer (EPMA) and a Fourier transform microscopic infrared spectrophotometer (microscopic FT-IR) were used. The microscopic FT-IR measurement was set to a reflection measurement mode. Si was detected by EPMA, and the periphery of the detected Si was measured by microscopic FT-IR. When an infrared spectrum corresponding to the organic part of the organosilicon compound was obtained, the region where the infrared absorption spectrum was obtained was determined to be the organosilicon compound.

[0206] <Dynamic friction coefficient>

[0207] A friction measuring machine manufactured by Shinto Science Co., Ltd. was used, and a SUS ball with a front end of 10 mmφ was used as a rubbing contact. The dynamic friction coefficient of the film surface was measured at a moving speed of 150 mm / min and a load of 1.0 N. In addition, the dynamic friction coefficient was also measured in a state where anti-rust oil was applied. The evaluation results are set as described below. It should be noted that the film with a dynamic friction coefficient of 0.2 to 0.5 (evaluation 3) in the non-oiled state and the film with a dynamic friction coefficient of less than 0.15 (evaluation 1) in the oiled state were evaluated to be the same as the dynamic friction coefficient of the previous chromate film, and the lubricity after oiling was excellent.

[0208] 3: Dynamic friction coefficient is 0.2~0.5

[0209] 2: Dynamic friction coefficient is 0.15 or more and less than 0.2

[0210] 1: Dynamic friction coefficient is less than 0.15

[0211] <Corrosion resistance>

[0212] The flat plate test piece was subjected to a salt spray test in accordance with JIS Z 2371 until a predetermined time. The evaluation criteria for corrosion resistance are shown below. 3 or more was considered acceptable.

[0213] (72 hours after salt spray test)

[0214] 4: White rust is less than 5%

[0215] 3: White rust exceeds 5% and is less than 15%

[0216] 2: White rust exceeds 15% and is less than 30%

[0217] 1: White rust exceeds 30%

[0218] <Painting Adhesion>

[0219] The test plate was coated under the following conditions and the coating film adhesion test was performed. It should be noted that the coating film adhesion evaluates the following two types of adhesion: the primary adhesion evaluated in the original state of the test plate (surface-treated metal plate); and the secondary adhesion evaluated assuming the use environment of the surface-treated metal plate. If any of the adhesions is unqualified, it is judged that the coating adhesion is insufficient.

[0220] (Painting conditions)

[0221] Painting conditions Paint: Amirac #1000 (registered trademark) manufactured by Kansai Paint Co., Ltd. (white paint)

[0222] Coating method: rod coating

[0223] Baking and drying conditions: 140°C, 20 minutes

[0224] Coating thickness: 25μm

[0225] The evaluation method is as follows.

[0226] (First-time tightness)

[0227] The test plate was scratched with an NT utility knife into 100 squares of 1 mm each, and a peel test was performed using an adhesive tape, and the number of peeled pieces of the coating film was used for evaluation. The evaluation criteria are shown below (3 or more indicates practical performance and is considered acceptable).

[0228] It should be noted that the "peeled number" here refers to the number of grids where peeling occurs in half or more of each grid (the "peeled number" described below also has the same meaning).

[0229] 4: The number of peeling pieces is less than 1

[0230] 3: The number of peelings is more than 1 and less than 20

[0231] 2: The number of peelings is more than 20 and less than 50

[0232] 1: The number of strippings exceeds 50

[0233] (Secondary Adhesion)

[0234] The test plate was immersed in boiling water for 2 hours, left for a day and night, and then 100 squares of 1 mm were cut with an NT utility knife. The peeling test was performed using adhesive tape, and the number of peeled coatings was used for evaluation. The evaluation criteria are shown below (3 or more is practical performance and is considered qualified.).

[0235] 4: The number of peeling pieces is less than 1

[0236] 3: The number of peelings is more than 1 and less than 20

[0237] 2: The number of peelings is more than 20 and less than 50

[0238] 1: The number of strippings exceeds 50

[0239] It should be noted that the mixing ratio (A / B) of the silane coupling agent (A) and the silane coupling agent (B) in Table 2A and Table 2B is the solid content mass ratio. In addition, the ratio (Y / W) of the phosphoric acid compound is the ratio of the solid content mass of P derived from the phosphoric acid compound to the solid content mass of Si derived from the organosilicon compound. The ratio (X / W) of the fluorine compound is the ratio of the solid content mass of F derived from the fluorine compound to the solid content mass of Si derived from the organosilicon compound. The ratio (Z / W) of the V compound is the ratio of the solid content mass of V derived from the vanadium compound to the solid content mass of Si derived from the organosilicon compound.

[0240] As shown in Tables 1 to 2F, for Inventive Examples 1 to 37, the dynamic friction coefficient is 0.2 to 0.5 in the non-oiled state, and the dynamic friction coefficient is less than 0.15 in the oiled state. This is about the same level as the dynamic friction coefficient of the conventional chromate film, and does not cause loosening when a plurality of plated steel sheets are stacked flat. Furthermore, when the plated steel sheets are roll-formed, the same setting conditions as in the case of the chromate film can be used, and there is no need to adjust the setting conditions for the processing.

[0241] Inventive Examples 1 to 42 were also excellent in corrosion resistance and coating film adhesion.

[0242] On the other hand, in Comparative Examples 1 to 6, the dynamic friction coefficient was less than 0.2 in the unoiled state and also less than 0.2 in the oiled state. This is different from the dynamic friction coefficient of conventional chromate coatings, and the dynamic friction coefficient in the unoiled state is particularly low, which caused loosening when a plurality of plated steel sheets were stacked flat. In addition, the coating adhesion was also insufficient.

[0243] In addition, in Comparative Example 7, since the atmosphere temperature in the first drying step was too low, drying was not sufficiently performed and the desired film could not be formed. In addition, in Comparative Example 8, since the atmosphere temperature in the first drying step was too high, drying was excessively performed and the desired film could not be formed.

[0244] [Table 1]

[0245] Metal plate No. Plating composition (mass %) M-1 Zn-0.2%Al M-2 Zn-6%Al-3%Mg M-3 Zn-11%Al-3%Mg-0.2%Si M-4 Zn-16%Al-6%Mg-0.2%Si M-5 Zn-19%Al-6%Mg-1.5%Sn-0.5%Ca-0.2%Si M-6 Zn-24%AI-12%Mg-0.5%Ca-1.2%Si M-7 Zn-11%Al-3%Mg-0.2%Si-0.05%Ni

[0246] [Table 2A]

[0247]

[0248] The underlined portion indicates that the method is out of the scope of the present invention or out of the scope of preferred production conditions.

[0249] [Table 2B]

[0250]

[0251] The underlined portion indicates that the method is out of the scope of the present invention or out of the scope of preferred production conditions.

[0252] [Table 2C]

[0253]

[0254] The underlined portion indicates that the method is out of the scope of the present invention or out of the scope of preferred production conditions.

[0255] [Table 2D]

[0256]

[0257] The underlined portion indicates that the method is out of the scope of the present invention or out of the scope of preferred production conditions.

[0258] [Table 2E]

[0259]

[0260] The underlined portion indicates that the method is out of the scope of the present invention or out of the scope of preferred production conditions.

[0261] [Table 2F]

[0262]

[0263] The underlined portion indicates that the method is out of the scope of the present invention or out of the scope of preferred production conditions.

[0264] Industrial Applicability

[0265] According to the present invention, it is possible to obtain a surface-treated metal sheet having a coating having lubricity comparable to that of a conventional chromate coating and having excellent corrosion resistance and coating adhesion.

[0266] Explanation of symbols

[0267] 1 surface treated metal plate, 11 steel plate, 12 coating, 13 film.

Claims

1. A surface-treated metal plate, characterized in that: It has: Steel plates; a plating layer including zinc formed on the steel sheet; and a film formed on the plated layer, The zinc content in the coating is 50% by mass or more. The film contains a zirconium compound, a vanadium compound, an organic silicon compound, a phosphate compound and a fluorine compound, and does not contain a Cr compound. The average value of the ratio of the solid content mass of F derived from the fluorine compound to the solid content mass of Si derived from the organic silicon compound, that is, F / Si, is 0.01 to 0.15, The average value of the ratio of the solid content mass of Zr derived from the zirconium compound to the solid content mass of Si derived from the organic silicon compound, i.e., Zr / Si, is 0.06 to 0.

15. The average value of the ratio of the solid mass of V derived from the vanadium compound to the solid mass of Si derived from the organic silicon compound, that is, V / Si, is 0.010 to 0.

200. When the surface roughness in a rectangular area of ​​the surface of the film with one side being 1 μm is expressed as an arithmetic mean height Sa, a maximum height Sz, and a root mean square roughness Sq, respectively, at least one of the following conditions is satisfied: arithmetic mean height Sa: 0.10 to 10.0 nm, maximum height Sz: 1.0 to 1000 nm, and root mean square roughness Sq: 0.10 to 100 nm.

2. The surface-treated metal plate according to claim 1, characterized in that: When the surface roughness in a rectangular area with one side of the surface of the film being 5 μm is expressed as an arithmetic mean height Sa, a maximum height Sz, and a root mean square roughness Sq, respectively, at least one of the following conditions is satisfied: arithmetic mean height Sa: 0.10 to 10.0 nm, maximum height Sz: 1.0 to 1000 nm, and root mean square roughness Sq: 0.10 to 100 nm.

3. The surface-treated metal plate according to claim 1 or claim 2, characterized in that: The film contains 1 to 100 granular organic silicon compounds with a major axis of 10 nm to 300 nm in a rectangular region with a side of 1 μm on the surface of the film.

4. The surface-treated metal plate according to claim 1 or claim 2, wherein: The average chemical composition of the coating contains, in mass %, Al: more than 4.0% and less than 25.0%, Mg: more than 1.0% and less than 12.5%, Sn: 0% to 20%, Bi: 0% or more and less than 5.0%, In: 0% or more and less than 2.0%, Ca: 0% to 3.0%, Y：0％～0.5％、 La: 0% or more and less than 0.5%, Ce: 0% or more and less than 0.5%, Si: 0% or more and less than 2.5%, Cr: 0% or more and less than 0.25%, Ti: 0% or more and less than 0.25%, Ni: 0% or more and less than 0.25%, Co: 0% or more and less than 0.25%, V: 0% or more and less than 0.25%, Nb: 0% or more and less than 0.25%, Cu: 0% or more and less than 0.25%, Mn: 0% or more and less than 0.25%, Fe: 0% to 5.0%, Sr: 0% or more and less than 0.5%, Sb: 0% or more and less than 0.5%, Pb: 0% or more and less than 0.5%, B: 0% or more and less than 0.5%, The remainder is Zn and impurities.

5. The surface-treated metal plate according to claim 3, wherein: The average chemical composition of the coating contains, in mass %, Al: more than 4.0% and less than 25.0%, Mg: more than 1.0% and less than 12.5%, Sn: 0% to 20%, Bi: 0% to less than 5.0%, In: 0% to less than 2.0%, Ca: 0% to 3.0%, Y: 0% to 0.5%, La: 0% to less than 0.5%, Ce: 0% to less than 0.5%, Si: 0% to less than 2.5%, Cr: 0% to less than 0.25%, Ti: 0% to less than 0.25%, Ni: 0% to less than 0.25%, Co: 0% or more and less than 0.25%, V: 0% or more and less than 0.25%, Nb: 0% or more and less than 0.25%, Cu: 0% or more and less than 0.25%, Mn: 0% or more and less than 0.25%, Fe: 0% to 5.0%, Sr: 0% or more and less than 0.5%, Sb: 0% or more and less than 0.5%, Pb: 0% or more and less than 0.5%, B: 0% or more and less than 0.5%, and the remainder is Zn and impurities.

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